Electromagnetic Radiation and Human Health

EMF Protection

This ebook is the complete guide to learning about electrical sensitivity and how to prevent getting it in your life. You will learn what electrical sensitivity is, and what causes it. Once you have started learning about it you will learn how to get rid of it and protect yourself from the dangers of electrical sensitivity. You will also learn how to heal yourself. This book is the product of careful research by the scientific and medical communities into the dangers and preventative measures of electrical sensitivity. ES is one of the most under-diagnosed conditions in the world right now, and this ebook is designed to education people as to how it works and how to prevent it. Do not let it take hold of your family; take control and prevent it now! Do not let yourself get any more hurt; learn about this condition and fight it!

How To Beat Electrical Sensitivity Overview

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Observation of Electromagnetic Radiations

The electromagnetic spectrum was described in Chapter 4 along with the relative frequencies and energies radiated by the sun and the earth due to their respective surface temperatures. In the case of passive sensors, these natural radiations, and their interaction with the earth and atmosphere, are what is sensed. Active sensors operate in exactly the same manner except that they provide a known spectral illumination of the target area and then sense the reaction of the target and atmosphere to the transmitted frequencies. Target Spectral Interaction Mechanisms. A number of interactions are possible when electromagnetic energy encounters a target or scene. The interactions can take place in a plane or two-dimensional surface (surface phenomena) or in three dimensions, resulting in interactions called volume phenomena. These surface and volume interactions can produce a number of changes in the incident electromagnetic radiation, such as changes in magnitude, direction, wavelength,...

103 Electromagnetic Interference Shielding Electromagnetic Reflection And Surface Electrical Conduction

The greater shielding effectiveness of filaments compared to fibers is because of the skin effect, i.e., high-frequency electromagnetic radiation interacts only with the near surface region of an electrical conductor. However, carbon filaments are still not as effective as nickel fibers of 2 pm diameter at the same volume fraction, as shown for a thermoplast matrix.23 On the other hand, by coating a carbon filament with nickel by electroplating, a nickel filament (0.4 pm diameter) with a carbon core (0.1 pm diameter) is obtained.23,35 Nickel filaments are more effective than nickel fibers for shielding, because of their small diameters. At 1 GHz, a shielding effectiveness of 87 dB was attained by using only 7 vol. nickel filaments in a thermoplast matrix.23 The shielding is almost all by reflection rather than absorption. Compared to magnetic technology, the attractions of electromagnetic technology are low material cost, low labor cost, low peripheral electronic cost, good mechanical...

Functional POP Electromagnetic Interference Shielding

Another commercially important application for electroless copper is electromagnetic interference (EMI) shielding of electronic components. The need to reduce (attenuate) electromagnetic signals (Ref 31) generated either internally or externally to a packaged component leads to the need to provide EMI shielding to the component. EMI shielding capability is directly related to the conductivity of the component hence, metal cases are highly effective in attenuating EMI. However, the same factors (cost and weight) that led to the use of plastics as base materials for decorative applications have also led to their implementation in electronic cabinetry. Because plastic enclosures are poor at attenuating EMI signals, a variety of coating methods have been developed to address this need. Methods that address the requirements of EMI shielding of plastic enclosures include electroless copper plating, as well as various types of metal-filled paints, zinc arc flame spray, sputtered or...

94 Electromagnetic Interference

Wind turbines have the potential to interfere with electromagnetic signals that form part of a wide range of modern communication systems and so their siting requires careful assessment in respect of electromagnetic interference (EMI). In particular, wind energy developments often compete with radio systems for hilltops and other open sites that offer high energy outputs from wind farms and good propagation paths for communication signals. The types of system that may be affected by EMI, and their frequency of operation, include VHF radio systems (30-300 MHz), UHF Television broadcasts (300 MHz-3 GHz) and microwave links (1-30 GHz). The interaction of wind turbines with defence and civilian radar used for air traffic control has also been the subject of investigation (ETSU, 1995). The electrical generator and associated control gear and electronics can produce radio frequency emissions but these may be minimized by appropriate suppression and screening at the generator. Rather than...

31 Lasers In The Electromagnetic Spectrum

The term laser is an acronym for a radiation source based on light amplification by stimulated emission of radiation. The foundation for lasers was established with the first formulation of a quantum theory of light by Planck and Einstein.1 Later, the technological development of lasers was stimulated by the invention of various microwave devices, which led in the 1950s to microwave amplifiers based on stimulated emission of radiation (masers). The quest for the development of devices based on this principle but operating at higher frequencies or shorter wavelengths started then and continues up to the present time. It led in 1960 to the construction and operation of the first laser that emitted visible radiation by Maiman.2 Today, lasers deliver radiation over large portions of the electromagnetic spectrum, ranging from the far infrared to the soft x-ray region (Fig. 3.1). FIGURE 3.1 The left-hand side shows an approximate energy and wavelength scale for the radiation. (The exact...

14 Convergence Of Technology And Automotive Systems

Why study EMC There are a number reasons. The first one is to understand how to meet various legal requirements for EMC in different countries. For example, the European Union and Canada both have requirements for radiated emissions. In the United States, emissions from electronic devices are regulated by the FCC however, what is unique about the automotive industry is that the devices on automotive systems are exempt from the radiated emission requirements included in Part 15 of the rules and regulations, provided they do not cause harmful interference.

13 Human Visual Perception

Electromagnetic radiation in the optical band generated from our visual environment enters the visual system through eyes and are incident upon the sensitive cells of the retina. The activities start in the retina, where the signals from neighboring receivers are compared and a coded message dispatched on the optic nerves to the cortex, behind our ears. An excellent account of human visual perception may be found in 16 , The spatial characteristics of our visual system have been proposed as a nonlinear model in 17, 18 .

13 Electronic Applications

Connections (solder joints, thick-film conductors, and thin-film conductors), dielectrics (electrical insulators in bulk, thick-film, and thin-film forms), substrates for thick films and thin films, heat sinks, electromagnetic interference (EMI) shielding, cables, connectors, power supplies, electrical energy storage, motors, electrical contacts and brushes (sliding contacts), electrical power transmission, and eddy current inspection (the use of a magnetically induced electrical current to indicate flaws in a material). Optical applications have to do with lasers, light sources, optical fibers (materials of low optical absorptivity for communication and sensing), absorbers, reflectors and transmitters of electromagnetic radiation of various wavelengths (for optical filters, low-observable or Stealth aircraft, radomes, transparencies, optical lenses, etc.), photography, photocopying, optical data storage, holography, and color control.

14 Thermal Applications

Thermal applications are applications that involve heat transfer, whether by conduction, convection, or radiation. Heat transfer is needed in heating of buildings in industrial processes such as casting and annealing, cooking, de-icing, etc., and in cooling of buildings, refrigeration of food and industrial materials, cooling of electronics, removal of heat generated by chemical reactions such as the hydration of cement, removal of heat generated by friction or abrasion as in a brake and as in machining, removal of heat generated by the impingement of electromagnetic radiation, removal of heat from industrial processes such as welding, etc. Radiation, i.e., blackbody radiation, is involved in space heaters. It refers to the continual emission of radiant energy from the body. The energy is in the form of electromagnetic radiation, typically infrared. The dominant wavelength of the emit

16 Environmental Applications

Electronic pollution is an environmental problem that has begun to be important. It arises from the electromagnetic waves (particularly radio waves) that are present in the environment due to radiation sources such as cellular telephones. Such radiation can interfere with digital electronics such as computers, thereby causing hazards and affecting society's operation. To alleviate this problem, radiation sources and electronics are shielded by materials that reflect and or absorb radiation. Chapter 4 addresses shielding materials.

123 Chromatic Dispersion

When an electromagnetic wave interacts with the bound electrons of a dielectric, the medium response, in general, depends on the optical frequency o> . This property, referred to as chromatic dispersion, manifests through the frequency dependence of the refractive index n( . On a fundamental level, the origin of chromatic dispersion is related to the characteristic resonance frequencies at which the medium absorbs the electromagnetic radiation through oscillations of bound electrons. Far from the medium resonances, the refrac-

21 Coherence Theory Of Light

In the classic theory of electromagnetic radiation, it is usually assumed that the electric and magnetic fields are always measurable quantities at any position. In this situation there is no need for the coherence theory to interpret the property of light. There are scenarios, however, in which this assumption cannot be made for these it is essential to apply coherence theory. For example, if we want to determine the diffraction pattern caused by radiation

135 Conclusions and Future Prospects

Bandwidth demands push the optical networks technologies from comparatively low speed to higher speed per channel. For this, the module technology development is moving toward extending module performance to higher speeds, better signal fidelity, less electromagnetic emissions, and hot pluggability for field installable flexibility. This pushes the necessity of high-scale integration of a variety of photonics and electronics devices in a single package. Figure 13.28 summarizes the trends and road maps

What does this mean

Almost all products are governed by regulations that constrain or prohibit certain inherent characteristics. Many of the regulations apply to human safety but some also apply to equipment safety such as those pertaining to electromagnetic radiation. There are also regulations that apply to the import and export of goods and environmental regulations that apply to pollution. While there may be no pollution from using the product, there may be pollution from making, moving or disposing of the product and therefore, regulations that apply to production processes are indeed product-related.

Remote Sensing Principles

Remote sensing is the collection of information about an object without being in physical contact with the object. Space-based remote sensors are also used for reference and control functions such as providing input for spacecraft attitude control, weapons guidance, spacecraft planetary landing, and spacecraft docking. In the context of this chapter, remote sensing will be restricted to data collection and to methods that employ electromagnetic energy as the means of detecting and measuring target characteristics. This definition excludes electrical, magnetic, and gravity surveys that measure force fields rather than electromagnetic radiation. Remote sensing systems employ the electromagnetic spectrum in unique ways to send and or collect natural or man-induced signals. The use of particular wavelengths and signals for remote sensing can be based on

32 Perception Of Colors

The human eye is sensitive to electromagnetic radiation in wavelengths ranging from 400 nm (violet) to 770 nm (red) 2 . The spectral response of the human eye is shown in Figure 3.1. It may be seen from Figure 3.1 that the eye responds to only a small spectral wavelength in the optical band of the entire electromagnetic spectrum. The machine vision systems today, however, can respond to a much larger extended spectrum ranging, from 780 nm to 1400 nm in the near-infrared range, 1400 nm to 3300 nm in mid-infrared, 3 to 10 ixm in far-infrared and also 100 nm to 380 nm in ultraviolet light range. This has been possible because of the availability of a large range of special sensors available for recording these signals. The object in the scene as perceived by human eyes or the camera system is characterized by its radiance R( ,x, y,t), where A is the wavelength of the electromagnetic radiation at position (x, y) and at time t for a particular color. There exists a direct relationship...

Electromagnetic Measurement

By placing a circular sample (with a hole at its center for the axial conductor) across the whole cross-section of a fixture resembling a coaxial cable (except larger), the interaction of the radiation with the sample can be studied. This method is called the coaxial cable method (also known as the transfer impedance method). Electromagnetic radiation incident on a sample may be partly reflected, partly absorbed, and partly transmitted. Measurement of the intensities of the transmitted wave and reflected wave can be achieved by using a network analyzer, an electronic instrument with source, receiver, and frequency sweep capability. The smaller the intensity of the transmitted wave, the greater the EMI shielding effectiveness.

Orbital angular momentum

Determines the temperature of a very hot surface from its incandescent brightness the image of the surface is focused in the plane of an electrically heated wire, and current through the wire is adjusted until the wire blends into the image of the surface. Also known as disappearing filament pyrometer. 'Sp-ta-kal pi'rSm-ad-ar optical radar See OPDAR. 'Sp-ta-kal 'rS.dSr optical rangefinder eng An optical instrument for measuring distance, usually from its position to a target point, by measuring the angle between rays of light from the target, which enter the rangefinder through the windows spaced apart, the distance between the windows being termed the baselength of the rangefinder the two types are coincidence and stereoscopic. 'Sp-ta-kal 'rSnj.fTnd-ar optical recording eng Production of a record by focusing on photographic paper a beam of light whose position on the paper depends on the quantity to be measured, as in a light-beam galvanometer. 'Sp-ta-kal ri'kord-ig optical...

Personnel Requirements

The health and safety issues related to the PAW process are very similar to those of other gas-shielded arc welding processes, especially GTAW. These include electrical shock electromagnetic radiation hazards, particularly ultraviolet radiation burns from hot metal parts and welding fumes and gases, including ozone. The volume of welding fumes produced is low and is similar to that produced by the GTAW process. Hexavalent chromium and ozone are concerns when welding stainless steels and aluminum alloys, respectively. Like the GTAW process, the low level of general welding fumes associated with PAW results in a comparatively higher level of ozone. However, the rapid decay of ozone within a short distance of the arc, coupled with the high degree of mechanization and automation typical of the keyhole plasma welding operation, means that operator exposure is generally very low. The microplasma mode, which is more commonly used manually, employs such low current levels that fume and ozone...

Spectral Radiometric Performance

The spectral performance of a sensor depends on the frequency (or wavelength) of the radiation which the sensor is designed to detect. The wavelength ) used to make a measurement is selected based on the radiative (radiometric) properties of the target and or on other considerations, such as interaction with or avoidance of the atmosphere or ionosphere. For instance, in clouds, water occurs as aerosol-sized particles of liquid rather than vapor. Clouds absorb and scatter electromagnetic radiation at wavelengths less than about 0.3 cm. Sensors are designed to take advantage of this effect to measure atmospheric characteristics. Only radiation of microwave and longer wavelengths is capable of penetrating clouds without being significantly scattered, reflected, or absorbed. These (radar) frequencies are commonly used when information below cloud layers is desired.

Product Life Cycle Checks and Automatic Testing

The classification of NT techniques is conventionally performed by means of transducing methods at the detecting front (Fig. 5.19), giving rise to a series of measurement devices for visual tests, electromagnetic radiation tests acoustic radiation tests, etc. With the expansion of intelligent instrumentation, a better classification should include the restitution procedures to give explicit account of the aids for self-calibration, for results consistency checks, for uncertainty computation, etc. Presently, large efforts are being put forth by instrumentation manufacturers, mainly in view of the friendliness of displayed outputs, by the introduction of the computerised restitution. This option is useful, as it avoids interpretation fuzziness, but should be normalised so that all devices (automatically) yield consistent results.

164 Sources of Radiation Dosage

First, solar radiation is the source of heat and light that supports plant and animal life on earth. We use its visible rays for sight the ultraviolet rays provide vitamin D, cause tanning, and produce sunburn the infrared rays give us warmth and finally, solar radiation is the ultimate source of all weather. Man-made devices produce electromagnetic radiation that is identical physically to solar, and has the same biological effect. Familiar equipment includes microwave ovens, radio and TV transmitters, infrared heat lamps, ordinary lightbulbs and fluorescent lamps, ultraviolet tanning sources, and X-ray machines. The gamma rays from nuclear processes have higher frequencies and thus greater penetrating power than X-rays, but are no different in kind from other electromagnetic waves. In recent years, concern has been expressed about a potential cancer hazard due to electromagnetic fields (EMF) from 60 Hz sources such as power lines or even household circuits or appliances. Biological...

1134 Radiographic examination

Electromagnetic radiation has properties that are useful for industrial radiography purposes. The rays travel in straight lines and cannot be deflected or reflected by mirrors or lenses they have wavelengths that enable the radiation to penetrate many materials, including most metals. They will, however, damage living tissue and therefore present some health and safety problems.

The Development of Modern Scanning Densitometry

Today's scanning densitometer measures reflectance, quenched fluorescence or fluorescence induced by electromagnetic radiation. For this reason, the instrument is now described as a spectrodensito-meter. Although all three detection modes are commonly used, fluorescence is limited by the fact that fewer substances can be induced to fluoresce. Many spectrodensitometers also have an attachment for scanning electrophoresis gels by transmission. The principle of operation is based on light of a predetermined beam size and wavelength striking the thin-layer surface perpendicularly whilst the TLC plate moves at a set speed under the stationary beam, or alternatively the beam traverses the stationary plate. Some of the electromagnetic radiation passes into and through the layer (transmitted light) whilst the remainder, due to the opaqueness of the layer, is reflected back from the surface. When the light beam passes over an absorbing chromatographic zone, there is a difference in optical...

25 Sources Of Noncoherent Optical Radiation

Human beings have been fascinated with the sun and the behavior of its electromagnetic radiation output for ages. It has proved to be one of the most interesting sources of light because its output is so dynamic. In actuality, its inherent output may not be highly variable but may only appear so to an earth observer. The changes in the amount of radiant intensity that we receive on earth are largely due to the changes in orientation between the sun and the earth. The zenith angle is the angle between the sun's present position and its position at noon on a given day. The larger the zenith angle, the longer the path length through which the solar radiation must travel. This longer path through the earth's atmosphere produces much more scattering of the shorter wavelengths, and the ultraviolet radiation is therefore reduced by a larger proportion at large zenith angles than is the visible and ir radiation. For example, the ultraviolet spectral irradiance at 300 nm decreases by a factor...

Advantages of optic fibers

When copper cables are placed side by side for a long distance, electromagnetic radiation from each cable can be picked up by the others and so the signals can be detected on surrounding conductors. This effect is called crosstalk. In a telephone circuit it results in being able to hear another conversation in the background. Crosstalk can easily be avoided in optic fibers even if they are closely packed.

344Ionising radiation4

Gamma-rays, X-rays and bremsstrahlung are all electromagnetic radiations similar in nature to ordinary light except that they are of much higher frequencies and energies. They differ from each other in the way in which they are produced. Gamma-radiation is emitted in radioactive decay. The most widely known source of X-rays is in certain electrical equipment in which electrons are made to bombard a metal target in an evacuated tube. Bremsstrahlung is produced by the slowing down of p particles its energy depends on the energy of the original p particles. The penetrating power of electromagnetic radiation depends on its energy and the nature of the matter through which it passes with sufficient energy it can pass right through a human body. Sources of these radiations outside the body can therefore cause harm. With X-ray equipment, the radiation ceases when the machine is switched off. Gamma-ray sources, however, cannot be switched off.

52 Background On Cementmatrix Composites

Cement-matrix composites for electronics include those containing short carbon fibers (for sensing strain, damage and temperature, for rendering p-type behavior, and for electromagnetic radiation reflection), short steel fibers (for thermoelectricity and for rendering n-type behavior), and silica fume (for helping fiber dispersion). This section provides background on cement-matrix composites, with emphasis on carbon fiber cement-matrix composites.

2223 Microwave and Radio Frequency Subassemblies

Microwave functionality is governed as much by mechanical design as by electrical design. The placement, orientation, and proximity of components to one another can greatly influence device electromagnetic fields, and thus affect system functionality at operating frequencies associated with microwave applications. At radio frequencies (RFs), signal speeds are very fast. The signal or current travels along the metal surface if the path length is too long, it can slow down the signal. Thus, when signal speed is the top priority, the signal path must be shortened by reducing the resistance. Resistance can be reduced by using a very electrically conductive material for the signal path, by using highly conductive die-attach materials, or by shortening the physical length of the paths. In some extreme cases, the only configuration that will meet the operating rise times required by the design is to stack the components on top of each other. In other cases, electromagnetic interference (EMI)...

42 Mechanisms Of Shielding

The primary mechanism of EMI shielding is reflection. For reflection of radiation, the shield must have mobile charge carriers (electrons or holes) that interact with the electromagnetic fields in the radiation. As a result, the shield tends to be electrically conducting, although a high conductivity is not required. For example, a volume resistivity of the order of 1 Q.cm is usually sufficient. However, electrical conductivity is not the scientific criterion for shielding, as conduction requires connectivity in the conduction path, whereas shielding does not. Although shielding does not require connectivity, it is enhanced by it. Metals are by far the most common materials for EMI shielding. They function by reflection due to the free electrons in them. Metal sheets are bulky, so metal coatings made by electroplating, electroless plating, or vacuum deposition are used for shielding.10-25 The coating may be on bulk materials, fibers, or particles, but coatings tend to suffer from...

Electromagnetic EM Methods

The EM methods use a transmitter coil to generate an electromagnetic field that induces eddy currents in the ground below the instrument. A receiver coil measures secondary electromagnetic fields created by the eddy currents and produces an output voltage that can be related to variations in subsurface conductivity as shown in Figure 9.14.1. Variations in subsurface conductivity may be caused by changes in the basic soil or rock types, thickness of the soil and rock layers, moisture content, fluid conductivity, and depth to the water table.

Detectors Electron Spin Resonance

Electron spin resonance was detected by the Russian scientist Zavoisky in 1946 while researching the paramagnetic properties of matter. Radicals and metal complexes with an odd number of electrons in d-orbitals show paramagnetism since unpaired electrons generate local electromagnetic fields. They can be detected whenever they interact with an external magnetic field. This interaction can be understood in the way that the external field forces any unpaired electron to align (Figure 1).

3410 Incidents and emergencies410

The National Arrangements for Incidents involving Radioactivity (NAIR) enables police to obtain expert advice on dealing with incidents (for example, transport accidents) that may involve radiation exposure of the public and for which no other pre-arranged contingency plans exist or, for some reason, those plans have failed to function. A source of radiological advice and assistance exists in each police administrative area - hospital physicists and health physicists from the nuclear industry, government and similar establishments. The scheme is co-ordinated by the National Radiological Protection Board at Chilton from whom further details are obtainable.

236 Institute of Nuclear Power Operations

Assistance programs that continually evolve to meet the changing needs of the nuclear industry help member utilities improve nuclear operations. Through assistance visits, working meetings, workshops, technical documents, and loan of personnel, INPO fosters comparison and exchange of successful methods among members. INPO carefully watches a set of performance indicators, which are quantified trends that measure success in achieving excellence. Examples are plant availability to produce electricity, industrial safety, safety system performance, fuel reliability, unplanned automatic scrams, radiation exposure, and volume of radioactive waste. With input from its Board of Directors and Advisory Council, INPO assists in setting target goals for the industry, with distinctions between PWRs and BWRs as appropriate. Fig. 23.1 shows trends over the years of two of the key performance indicators, unplanned scrams and radiation exposure, as a composite for the two types of reactor.

Considerations Of Radioactivity

The Nuclear Regulatory Commission (NRC) provides specifications detailing the allowable radiation exposure to personnel. Any pump that produces radioactivity at rates that would exceed these limitations must either be repaired at a facility licensed to handle contaminated material or be decontaminated prior to being sent to a conventional repair shop.

Computer Exercises

BASIC program EXPOSO looks up gamma ray attenuation coefficients and buildup factors on data tables and finds the radiation exposure at a distance from a point source. (a) Run the program and explore its menus. (b) Verify that the flux at 10 cm from a point millicurie 1 MeV gamma ray source in lead is 39.2 cm2-s.

346 Quantities and units

Biological damage does not depend solely on the absorbed dose. For example, one Gy of a radiation to tissue can be much more harmful than one Gy of p radiation. In radiological protection, it has been found convenient to introduce a further quantity that correlates better with the potential harm that might be caused by radiation exposure. This quantity, called the equivalent dose, is the absorbed dose averaged over a tissue or organ multiplied by the relevant radiation weighting factor. The radiation weighting factor for y radiation, X-rays and p particles is set at 1. For a particles, the factor is 20. Equivalent dose is expressed in a unit called the sievert, Sv. Submultiples of the sievert are frequently used such as the millisievert, mSv (a thousandth of a sievert) and the microsievert, Sv (a millionth of a sievert).

162 Radiation Dose Units

We shall describe the methods of calculating dosage in Chapter 21. For perspective, however, we can cite some typical figures. A single sudden exposure that gives the whole body of a person 20 rems (0.2 Sv) will give no perceptible clinical effect, but a dose of 400 rems (4 Sv) will probably be fatal the typical annual natural radiation exposure of the average citizen including radon is 295 millirems medical and dental applications give another 54, with all other sources 11, giving a total of 360 millirems (3.6 Sv). Fig. 16.1 shows the distribution by percentages. Earlier literature on radiation protection cited typical annual dose figures of 100 mrems (0.1 rem), but in recent times the effect of radon amounting to around 200 mrems y has been included. Computer Exercise 16.A addresses the buildup

161 Physiological Effects

As a good rule of thumb, 32 eV of energy is required on average to create an ion pair. This figure is rather independent of the type of ionizing radiation, its energy, and the medium through which it passes. For instance, a single 4-MeV alpha particle would release about 105 ion pairs before stopping. Part of the energy goes into molecular excitation and the formation of new chemicals. Water in cells can be converted into free radicals such as H, OH, H2O2, and HO2. Since the human body is largely water, much of the effect of radiation can be attributed to the chemical reactions of such products. In addition, direct damage can occur, in which the radiation strikes certain molecules of the cells, especially the DNA that controls all growth and reproduction. Turner (see References) displays computer-generated diagrams of ionization effects. If a radioactive substance enters the body, radiation exposure to organs and tissues will occur. However, the foreign substance will not deliver all...

229 Nuclear Power Plant Decommissioning

Operation of the reactor over a long period of time will have resulted in neutron activation, particularly of the reactor vessel and its stainless steel internal parts. Contamination of other equipment in the system will include the same isotopes that are of concern in low-level waste disposal. Various techniques are used to decontaminate-washing with chemicals, brushing, sand blasting, and ultrasonic vibration. To cut components down to manageable size, acetylene torches and plasma arcs are used. Since such operations involve radiation exposure to workers, a great deal of preplanning, special protective devices, and extra manpower are required. A very large volume of waste is generated. Some of it may be too active to put into a low-level waste disposal site, but will not qualify for disposal in a high-level waste repository. Cobalt-60 dominates for the first 50 years, after which the isotopes of concern are 76,000-year nickel-59 and 24,000-year niobium-94.

214 Internal Exposure

We now turn to the exposure of internal parts of an organism as a result of having taken in radioactive substances. Special attention will be given to the human body, but similar methods will apply to other animals and even to plants. Radioactive materials can enter the body by drinking, breathing, or eating, and to a certain extent can be absorbed through pores or wounds. The resulting dosage depends on many factors (a) the amount that enters, which in turn depends on the rate of intake and elapsed time (b) the chemical nature of the substance, which affects affinity with molecules of particular types of body tissue and which determines the rate of elimination (the term biological half-life is used in this connection, being the time for half of an initial amount to be removed) (c) the particle size, which relates to progress of the material through the body (d) the radioactive half-life, the energy, and kind of radiation, which determine the activity and energy deposition rate, and...

345 Biological effects of ionising radiation48

Low doses or high doses received in a protracted fashion may lead to damage at a later stage. With reproductive cells, the harm is expressed in the irradiated person's offspring (genetic defects), and may vary from unobservable through mildly detrimental to severely disabling. So far, however, no genetic defects directly attributable to radiation exposure have been unequivocally observed in human beings. Cancer induction may result from the exposure of a number of different types of a cell. There is always a delay of some years, or even decades, between irradiation and the appearance of a cancer.

347 Basic principles of radiological protection

The primary aim of radiological protection as expressed by ICRP5 is to provide an appropriate standard of protection for man without unduly limiting the beneficial practices giving rise to radiation exposure. For this, ICRP has introduced a basic framework for protection that is intended to prevent those effects that occur only above relatively high levels of dose (e.g. erythema) and to ensure that all reasonable steps are taken to reduce the risks of cancer and hereditary damage. The system of radiological protection by ICRP5 for proposed and continuing practices is based on the following general principles 3 detecting of unusual and unexpected situations involving radiation exposures, 5 provision of data on which the effect of future operations on radiation exposure can be predicted so that the appropriate controls can be devised beforehand and instituted.

196 The Chernobyl Accident

Graphite moderator caught fire, and a large amount of radioactive material from the damaged nuclear fuel was released into the atmosphere. The amount of radiation exposure to workers and the public is not precisely known, but the doses exceeded those from fallout from earlier weapons tests. A number of workers were killed, nearby towns were contaminated, and it is estimated that the collective dose to the public increased the cancer risk. A large number of people were evacuated from the town of Pripyat. Agriculture was disrupted in the Soviet Union and a ban on food imports was imposed by several European countries.

217 Newer Radiation Standards

A major revision of regulations on radiation exposure was proposed by the Nuclear Regulatory Commission in 1986, published as a Final Rule in 1991, and required for use from January 1, 1994. The newer version of the rule 10CFR20f, intended to provide greater protection for both workers and the public, was based on recommendations of the International Committee on Radiological Protection (ICRP).

Inorganic Ion Exchangers and Application of Inorganic Layered Materials

A reawakening of interest in inorganic ion exchangers was connected with the search for materials which can withstand high temperature, ionizing radiation and some aggressive chemicals. In 1943, Russel et al. discovered that insoluble zirconium phosphate is suitable for the separation of uranium and plutonium from nuclear fission products. Thus, a new class of inorganic ion exchangers was synthesized on the basis of group 4 elements, mainly of titanium and zirconium. Various kinds of functional groups can be attached to the polymer chains consisting of Ti or Zr atoms bonded to oxygen, producing different types of ion exchangers. It is a well-known fact that zirconium readily forms chains

727 Friction torque caused by the working medium

The progress of space research has made a series of specific demands on the operation of rolling-contact bearings. In outer space conditions, there are many factors, such as the low pressure of the surrounding medium, ionizing radiation, absence of gravitation, presence of substances in the state of plasma, that appreciably modify the nature of the friction process.

Semiconductor Manufacturing

The mask is laid on the wafer and its back surface is flooded with ionizing radiation, such as ultraviolet light or low-energy X-rays. The radiation is blocked in areas where the mask has opaque material on its surface. Where there is no opaque material on the mask surface, the ionizing radiation passes through into the resist, the silicon dioxide, and silicon. The ionizing radiation has little effect on the silicon dioxide and silicon but it breaks down the molecular structure of the resist into smaller molecules. This step makes it possible to dissolve exposed resist material in solvents that will not dissolve the unexposed resist material.

Additional Sources of Reactor Waste

Naturally occurring radionuclides like those listed in Table 16-10 may pose threats to public health. As may be seen in Table 16-4, by far the largest fraction of background ionizing radiation comes from radon (Rn-222). Rn-222 is a member of the uranium decay series and is thus found ubiquitously in rock. Chemically, Rn-222 is an inert gas, like helium, and does not become chemically bound. When uranium-bearing minerals or rock are crushed or machined, Rn-222 is released there is even a steady release of

Radioactivity Analysis

Detection, identification, and quantification of the specific radionuclide responsible for the presence of ionizing radiation is very often required. Identification of the radionu-clide facilitates the design of systems to safely and economically handle radioactive materials. Many different types of instruments, ranging in price from several thousand to several hundred thousand dollars, are available. Field measuring devices are often used to detect and approximate the amount of radiation present. Identification and quantification is usually performed in a controlled laboratory area, equipped to minimize background interference and gross contamination, and to ensure personnel safety.

541History of Occupational Environment

Physical hazards present in the work environment include noise, temperature extremes, ionizing radiation, and nonionizing radiation. These agents at certain levels will severely damage the human body. Noise, which is defined as unwanted sound, will impair hearing to the point of deafness if the noise levels are high enough. One of the dangers of this hazard is that many people do not realize the permanent consequences of working constantly with high noise levels. Many workers think their hearing will return to normal when they leave the noisy work area. In fact, chronic exposure to high noise levels will The physical hazards of radiation, which are divided into ionizing and nonionizing radiation, may not be as familiar to the reader as other physical hazards. Nonionizing radiation is composed of ultraviolet light, visible light, infrared light, microwaves, and radio frequencies. The sources and uses of nonionizing radiation are becoming more prevalent in industry. The associated...

182 Radiation Preservation of Food

On the other hand, research has shown that gamma radiation processing can serve as an economical, safe, and effective substitute and supplement for existing treatments. The shelf-life of certain foods can be extended from days to weeks, allowing adequate time for transportation and distribution. It has been estimated that 20 to 50 percent of the food supplied to certain countries is wasted by spoilage that could be prevented by radiation treatment. The principal sources of ionizing radiation that are suitable for food processing are X-rays, electrons from an accelerator, and gamma rays from a radionuclide. Much experience has been gained from the use of cobalt-60, half-life 5.27 years, with its two gamma rays of energy 1.17 MeV and 1.33 MeV. The largest supplier of cobalt-60 is a Canadian firm, MDS Nordion, formerly part of Atomic Energy of Canada, Ltd. The isotope is prepared by irradiating pure cobalt-59 target pellets with neutrons in the CANDU reactors of Ontario Hydro. The...

215 The Radon Problem

Well down the chain is radium-226, half-life 1599 years. It decays into radon-222, half-life 3.82 days. Although radon-222 is an alpha emitter, its shorter-lived daughters provide most of the dosage. Radon as a noble gas along with its suspended particulate decay products is breathed in with air. Some radioactive particles deposit on the lung surfaces. Decay of the radon and its daughters releases ionizing radiation.

49 Filtering Overview

As stated before, the purpose of the EMI filter is to prevent the entry or exit of undesired electromagnetic energy from equipment. A filter absorbs the noise energy through the use of lossy elements such as resistors and ferrite components, or reflects the noise energy back to the source through use of reactive elements. Generally, EMI filters are low-pass filters with effectiveness depending on the impedances of the elements at either end of the filter.

Ground Penetrating Radar GPR Methods

Environmental engineers often use the GPR methods to locate buried objects, map the depth to shallow water tables, and delineate soil horizons. The principles involved in GPR technology are similar to those in seismic refraction, except that in GPR, electromagnetic energy is used instead of acoustic energy, and the resulting image is relatively easy to interpret.

Classification of Remote Sensors

Earlier in this chapter, we identified passive remote sensors that collect electromagnetic energy. The camera (without lighting aids such as a flash unit) is the classic example of a passive sensor Incoming light impinges on sensitive film which retains the image. Radiometers are devices that replace the film with detectors that are sensitive to the incoming radiation (which can be in other portions of the electromagnetic spectrum besides the visible frequencies) and convert the information to electronic signals that can be transmitted to and evaluated by users on the ground. Collection devices include lenses and antennas that focus the energy on detectors such as solid state materials, charge coupled devices (CCDs), and other spectrally unique and energy-sensitive conversion elements.

Intensity of the Scattered Light

On a spherical particle located at the origin of a Cartesian coordinate system. The light can be resolved into two linearly polarized components that can each act independently of the other. If the particle is small compared with the wavelength of the light, then there is a uniform instantaneous electromagnetic field over the particle. As a consequence the particle will become polarized in the direction of the field. The net result is to produce a dipole that will oscillate synchronously and in the same direction as the vibrating electric field. The oscillating dipole will radiate electromagnetic energy and this scattered radiation will be polarized in the same sense as the dipole.

Electromagnetic Interaction

We previously determined the amount of electromagnetic energy that reaches the vicinity of the earth when we calculated the solar constant. This energy retains the blackbody spectral characteristics it had when it left the sun, the only difference being that the energy levels over the range of wavelengths has decreased. As this energy encounters the earth, the interactions affect both the earth and the energy itself. In some cases, these interactions are useful to the space systems user. For example, remote sensing techniques measure the absorption or transmission of solar radiation through the atmosphere to infer some of the characteristics of the atmosphere from space, and most spacecraft use solar panels to convert some of this radiation to electricity to power the spacecraft systems. In other cases, solar radiations produce undesired effects. For instance, spacecraft may absorb excess infrared frequencies, necessitating the use of thermal control devices, and the ionosphere,...

410 Enclosure Shielding

Most books on shielding delve into a comprehensive coverage of shielding theory that is beyond the scope of this handbook. Guidelines provided here provide a minimum of mathematics and theory. Shielding of EM fields is accomplished through reflectance or absorption of the fields by a barrier. In most applications, the barrier is a metal, although coated and conductive plastics are being used more frequently in commercial applications. An important point to remember in shielding is that the actual shielding provided by a metal barrier depends on the type electromagnetic field that predominates. Reflection is highly effective against predominately electric fields and plane waves and has little effect on predominately magnetic fields. Absorption in a metal barrier is exponential in nature, i.e., as an electromagnetic field passes through a metal barrier, the amplitude of the electromagnetic field decays exponentially. At some distance into the metal barrier, the amplitude of the...

Optical Waveguide Modes

An optical waveguide directs the propagation of an electromagnetic field through a nearly lossless doped silica medium. We refer to the propagating field as the lightwave. The field obeys Maxwell's equations. Because the changes in refractive index n(x) are small, Maxwell's equations reduce to a scalar wave equation for the transverse electric field. At a single wavelength A and polarization, the scalar wave equation is

52 Characteristics Of The Electromagnetic Environment

The inverse distance relationship is shown in the simple demonstration of a transmitter and a field strength meter in Figure 5.1.a. As a transmitter is feeding power to an antenna, the transmitted power will produce an electromagnetic field in space. A common way to measure this field is by measuring it with a field-strength meter. The field-strength meter will measure this field and display the field strength. As the field-strength meter is moved further away from the antenna, the field strength-indication will decrease. If the field strength meter is moved closer to the antenna, the reading will increase. A good analogy is to think about the relative brightness on a surface from a flashlight, the further away from the flashlight, the illumination per unit area is less, although the total light from the bulb has not changed.

Theoretical Considerations in MAE

Microwaves are high-frequency electromagnetic waves placed between radio frequency and the infrared regions of the electromagnetic spectrum (their frequency range from 0.3 to 300 GHz corresponding to wavelengths of 1 m to 1 mm). In contrast to conventional heating where the heat penetrates slowly from the outside to the inside of an object, in MAE the heating appears right in the core of the body that is being heated, and the heat spreads from the inside to the outside of that body. The microwave energy affects molecules by ionic conduction and dipole rotation. In ionic conduction, the ions in solution will migrate when an electromagnetic field is applied. The resistance of solution to this flow of ions will result in friction and, thus, heating of the solution. Dipole rotation means realignment of the dipoles with the applied field. At 2450 MHz, the dipoles align and randomize 4.9 x 109 times per second this forced

The Curie Point Pyrolyser

The adoption of inductive heating by Giacobbo and Simon in 1964 was very quickly recognized to possess many virtues. The most important is found in the fact that final skin temperature (the Curie Point) is a function of the composition of the ferromagnetic conductor when subjected to a given radiofrequency electromagnetic field. Additionally, the skin heating rate is constant for wires of identical cross-section. Moreover, there is no risk of cross-contamination as a 'virgin' wire can be used for each pyrolysis. Sterile storage and handling of new wires is the only precaution necessary.

Vertical Dynamics Of A Superconducting Suspension Sy Stem

Two mathematical models of this problem, which differ in the approach used for describing the electromagnetic transient, are considered. One of the two models is based on the partial differential equation of the time-varying electromagnetic field, which is generated when a perturbation in vertical direction occurs. This equation can be solved numerically by a two-dimensional, finite-element analysis in the space dimension and by a time-stepping procedure in the time dimension In the other model the electromagnetic phenomena are represented by lumped parameter circuit equations. The self- and mutual inductances of the circuits are calculated as functions of the levitation height by a finite-element analysis of stationary magnetic fields. In both the models the vertical motion equation is solved by a time-stepping procedure. The lift force per unit length, which has to be introduced at each step in the motion equation, is calculated by Maxwell stresses in the former model and in terms...

Communications Theory

Figure 5-1 reviews some of the terms that describe the characteristics of electromagnetic waves as discussed in Chapter 4. Figure 5-1 reviews some of the terms that describe the characteristics of electromagnetic waves as discussed in Chapter 4. As we will see in this section, electromagnetic waves are used for communication purposes to carry information between locations. Before describing this process, however, some additional information on electromagnetic propagation must be presented. These properties and phenomena also apply to remote sensing and satellite navigation, discussed later.

71 Neuroscience and Psychology of Attention

In one famous experiment on human attention, event-related potentials (ERP) are measured via sensors on the scalp of a man via detection of electromagnetic waves. A specific ERP signal is the so-called auditory N1 potential. The average voltage response for this ERP to an auditory stimulus that is attended to is relatively large in magnitude compared to an auditory stimulus that is not attended to. Some signals in the brain are amplified due to attention, and attenuated via lack of attention.

858 Travelingwave Photodiodes

To design high-speed photodetectors, a traveling-wave (TW) photodiode was developed 65, 66 , This is a waveguide photodiode with an electrode structure designed to support traveling electromagnetic waves with a phase velocity or a characteristic impedance matched to that of the external circuit, as shown in Fig. 8.37. In a TW photodetector, the optical dielectric waveguide is designed to also be an electrical waveguide for propagating electric wavefields. Because the TW photodetector is an electrically distributed structure, it is free from the RC limitation of the waveguide photodetector. As a result, larger bandwidths can be obtained compared to those obtained by using waveguide photodetectors. The bandwidth of TW photodetectors is limited by the optical absorption coefficient and the velocity mismatch between the optical and the electrical waves. The absorption contribution to the bandwidth is practically independent of the device length, which means that TW photodetectors with...

517Qualification testing

Qualification testing is used to determine the flightworthiness of the LRUs which comprise the AFCS. A number of tests are undertaken, such as vibration, temperature altitude variation, humidity, electromagnetic interference, crash shock testing, contamination and fungus-resistance growths, plus others dependent on the application. This testing uses selected units identical to the type which will ultimately fly and is concerned with proving that the performance of the hardware will not degrade when in a typical aircraft environment.

85 Summary Of Motor Characteristics And Typical Applications

8.6 ELECTROMAGNETIC INTERFERENCE (EMI) Many motors are used in sensitive applications that require that specific limits of radiated or conducted electromagnetic interference not be exceeded. Electromagnetic interference (EMI), sometimes referred to as radio-frequency interference (RFI), is a phenomenon which can directly or indirectly contribute to a degradation in performance of electronic receivers or systems. EMI consists of undesirable voltages and currents that reach the affected device either by conduction through the power lines or by radiation through the air and cause the device to exhibit undesirable performance.

634 Electromagnetic compatibility testing

Electromagnetic interference (EMI) represents a serious problem for an electronic flight control system since it provides a mechanism for potential common-mode failures in a multi-redundant FCS. Malfunctions caused by EMI can range between being insignificant in nature to causing catastrophic failures. EMI can be both internally and externally sourced and the FCS design process must address these issues. The flight control computers, control surface actuators, sensors units (inertial, air data etc.) as well as all pilot inceptors, switches and all databus inputs and wiring associated with the FCS must be designed to be resistant to all forms of electromagnetic interference. This will include radiofrequency (RF), microwave, lightning and EMP (electromagnetic pulse) sourced interference.

51 Overview of Fiber Optics in Oceanographic Applications

The transmission of signals over fiber optic media has now become a trend of major economic importance. This is due mainly to the many advantages offered over conventional transmission methods using metallic conductors. An ability to carry high bandwidth signals and to eliminate electromagnetic interference in high signal environments are perhaps the most significant. In underwater applications, the use of fiber optics for long-haul telemetry in transoceanic telephone transmission is well-known however, fiber optics is also of great importance in sensing, as well as in vehicle control and communications. Much of the theory relating to fiber optic transmission was developed decades ago, and recent advancements have been primarily in cabling, networking, sensor development, and specialized connector and splice designs. With these advancements have come reductions in component costs, and resulting commercial opportunities.

177 Electronic instrumentation

Instruments with a balanced input circuit are available for measurements where both input terminals are normally at a potential other than earth. Further problems arise due to common-mode interference arising from the presence of multiple earth loops in the circuits. In these cases the instrument may need to be isolated from the mains earth. Finally, high-frequency instruments, unless properly screened, may be subject to radiated electromagnetic interference arising from strong external fields.

Biological Ultraviolet And Visible Systems

The electromagnetic spectrum extends from gamma and X rays of wavelengths less than 0.1 nm through ultraviolet, visible, infrared, radio, and electric waves. The solar spectrum of radiation that reaches the earth's surface ranges from 300-900 nm radiation in the ultraviolet (200300 nm) is mostly absorbed by the ozone layer in the upper atmosphere. Light that passes through the atmosphere reaches the earth's surface and also enters large water bodies. As penetration increases, the extremes of the visible spectrum are absorbed, allowing a narrow radiation of

Biological Infrared Detection

Before delving into the specifics of biological infrared detection, a brief tutorial on blackbody radiation and thermal sources of IR is needed. Warm objects, such as mammals, emit energy in the infrared part of the electromagnetic spectrum. Table 1 lists three different temperatures 300 K is listed as a background temperature, 310 K is listed to represent 37 C prey, and the 1000 K listing is representative of a forest fire. The 310 K listing and the 1000 K listing pertain to the snake model and beetle model of infrared

132 Satellite Sensors And Imageries

The first remote sensing satellite LANDSAT was launched by United States in 1972. It contained onboard image vidicon cameras operating in three separate visible wave lengths bands. The multispectral scanning system of LANDSAT provided four-band images of the earth's surface. These four-band images were captured in four wave-lengths three in the visible and one in the near-infrared portion of the electromagnetic spectrum. The satellite located at about 912 kilometer away from the earth completes one revolution around the earth in around 1 hour 43 minutes. It completes fourteen orbits a day with repetitive coverage of eighteen days. Four more LANDSAT satellite were subsequently launched which were located at an orbital altitude of 705 kilometer. The LANDSAT-MSS sensors having cross track scanning were incorporated in all the five LANDSAT satellites. The spatial resolution of LANDSAT MSS data is 56 m x 79 m.

Measurement of Seal Face Flatness

Actual Size Pvc Pipe

White light from the sun is actually a combination of several colors, each of which represents a different wavelength of electromagnetic energy. If sunlight were used to measure seal face flatness, each color would generate its own pattern of bands on the optical flat. A far more practical light source for this purpose is one that provides light of only one color a monochromatic light source.

2110 References for Chapter

International Basic Safety Standards for Protection Against Ionizing Radiation, Safety Series No. 115, International Atomic Energy Agency, Vienna, 1996. Extensive tables of limits. 8.8 Information Relevant to Ensuring that Occupational Radiation Exposures at Nuclear Power Stations Will Be As Low As Reasonably Achievable, June 1978 (pdf 1192 KB). Committee on the Biological Effects of Ionizing Radiations, National Research Council, Health Risks of Radon and Other Internally Deposited Alpha-Emitters, BEIRIV, National Academy Press, Washington DC, 1988. Emphasizes lung cancer and the relationship of smoking and radon. International Basic Safety Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources, Safety Series No. 115, IAEA, Vienna, 1996. Policies, practices, and extensive dose limit tables.

Induced Ac Voltages On Pipelines May Present A Serious Hazard

Electromagnetic coupling is also known as transformer action. When current flows in an energized conductor, it produces an electromagnetic field at right angles to the conductor. In AC power systems, electric current flowing in the conductor changes direction 120 times per second for 60-Hz and 100 times per second to 50-Hz systems. Thus, the electromagnetic field surrounding the energized conductor is constantly expanding and contracting.

710 Orientation by Nonmechanical Means

Skin Pictures Hexavalent Chromium

We discuss here some ideas based on the use of electromagnetic fields for orientation. Figure 7.60 shows a classification of the different combinations of materials and electromagnetic fields that are used. We will present some examples relevant to electrostatic, magnetostatic, and alternating magnetic fields (some other special cases are omitted) in combination with parts made of ferromagnetic or nonmagnetic conductors or dielectric materials. The diagram in Figure 7.60 indicates that FIGURE 7.60 Classification of electromagnetic fields in combination with materials of different natures. matic Feeding Systems in the Instrument Construction Industry (Mashinostrojenie, Moscow, 1966) (in Russian). A book relevant to the subject of orientation by means of electromagnetic fields is that by Dr. B. Yoffe and R. K. Kalnin Orientation of Parts by Electromagnetic Fields (Zinatne, Riga, 1972) (in Russian).

Howard Coffey Jianliang He and Zian Wang

Since the four conceptual maglev systems designed under the NMI program were developed analytically without the benefit of experience with operational systems, a government team was established to independently analyze the proposed concepts 1 . These designs included three electrodynamic (EDS) and one electromagnetic (EMS) system. One EDS concept used coils, another a conducting ladder, and the third a conducting sheet in the guideway. The EMS concept used iron-cored superconducting magnets aboard the vehicle. Null-flux coils were used in two guidance systems. No single method of analysis was adequate for calculating the electromagnetic fields and forces of all the systems proposed.

167 References for Chapter

Upton, The Biological Effects of Low-Level Ionizing Radiation, Scientific American, February 1982, p. 41. Describes the mechanism of biological damage and compares risks from radiation with risks from other situations or activities e.g., smoking or driving. Also discusses errors in perception of risk. Health Effects of Exposure to Low Levels of Ionizing Radiation BEIR V, Committee on the Biological Effects of Ionizing Radiation, National Research Council, National Academy Press, Washington, DC, 1990. A report on the state of knowledge about radiation effects, with special attention to genetic effects and cancer. An update of the study BEIR III in 1980. Health Effects from Exposure to Ionizing Radiation Environmental Protection Agency Fact Sheet Richard Wilson, Resource Letter EIRLD-1 Effects of Ionizing Radiation at Low Doses, American Journal of Physics 67, pp. 372-377 (1999). Puts radiation risks into perspective.

Ecosystem Risk Assessment

3.3 The International Commission on Radiation Protection has determined the lifetime unit risk for cancer for low-energy ionizing radiation to be 5.4 x 10 4 per rem of absorbed radiation. The allowed level of ionizing radiation (the EPA standard) above background is 25 mrem per source per year. Average background is about 360 mrem per year. How many fatal cancers attributable to ionizing radiation would result in the United States each year if the entire population were exposed at the level of the EPA standard How many cancers may be attributed to background If only 10 of the cancers were fatal each year, what percentage of the annual cancer deaths in the United States would be attributed to exposure to background radioactivity (Note what unit risk means in this problem.) 3.4 The allowed occupational dose for ionizing radiation is 1 rem per year. By what factor does a worker exposed to this dose over a working lifetime increase her risk of cancer

Electromagnetic Applications Of Biomimetic Research

Sensing electromagnetic radiation is of particular interest in aviation because of the increasing distances over which sensors operate. The ability to detect EM in the infrared without cryogenics has been an important technology driver because of increased sensor reliability and reduced payloads. The latter are becoming more important as space migration dominates defense and commercial interests. Against this backdrop, it is easy to see why biomimetics, and in particular biomimetic EM sensing, has been a growing part of research in many funding agencies. The ability of insect structures like hairs or microscopic spines to gather electromagnetic radiation was postulated by Callahan (42). In that publication, insect antennae are considered dielectric waveguides that work in the infrared. Similarity is drawn between this biological structure and a drawing of an electromagnetic wave energy converter (EWEC) that was patented through NASA (US Pat. No. 3,760,257) for converting microwave EM...

2810 Porsche Tiptronic electronic control system

The electronic control unit, which is supplied by Bosch, has an 8-bit microprocessor with an external 32 kB EPROM memory. It has 42 inputs and outputs, and all control unit interfaces are short circuit resistant and protected also against incorrect connection. The unit is screened against interference by external electromagnetic fields. A diagnostic program monitors internal voltages and carries out plausibility checks on groups of input signals. It detects and records even sporadic failures within the system. If appropriate, it selects substitute functions, illuminates a warning lamp on the fascia, and stores all the relevant information ready for transmission to the diagnostic equipment available in all Porsche dealerships.

335 Propagating brush discharges

Compared with the types of gas discharge already described, propagating brush discharges (Lichtenberg discharges) are, with the exception only of lightning flashes, the most powerful kind of electrostatic discharge. As the inductive reactance (inductivity) of a propagating brush discharge circuit is extremely low in comparison with, say, that of a spark discharge circuit, the current rise-time of a propagating brush discharge is correspondingly much faster, resulting in sharp pulses. The effect of the electromagnetic radiation from such pulses can be to induce damaging potentials and charges on any electronic equipment in the vicinity.

Electrical properties of metal foams

The electrical conductivity of a metal foam is less than that of the metal from which it is made for the obvious reason that the cell interiors, if gas-filled, are non-conducting. One might guess that the conductivity should vary linearly with the relative density, but the real dependence is stronger than linear, for reasons explained below. Though reduced, the conductivity of metal foams is more than adequate to provide good electrical grounding and shielding of electromagnetic radiation.

412Building the Luenberger Observer

Phase lag and attenuation can be caused by the physical construction of the sensor or by sensor filters, which are often introduced to attenuate noise. The key detriment of phase lag is the reduction of loop stability. Noise can be generated by several forms of electromagnetic interference (EMI). Noise causes random behavior in the control system, corrupting the output and wasting power. All of these undesirable characteristics are represented by the term GS(s) in Figure 4-2. The ideal sensor can be defined as GSIDEAL(s) 1.

13 Minimum ignition energy

A further complication is that not all of the energy released by the capacitor in a spark is converted into thermal energy. Some of the energy is lost as heat in the wiring of the discharge circuit and to the electrodes across which the spark passes some is lost in the form of light and electromagnetic radiation and some by the pressure exerted by the spark. Also, there is always a small residual charge left on the capacitor after the discharge. Thus, the determination of MIE is, intrinsically, prone to error and so the measurement of precise values is not possible.

2141 Errors in Feedback Sensors

Stochastic or nondeterministic errors are those errors that cannot be predicted. The most common example of stochastic error is high-frequency noise. High-frequency noise can be generated by electronic amplification of low-level signals and by conducted or transmitted electrical noise commonly known as electromagnetic interference (EMI). High-frequency noise in sensors can be attenuated by the use of electrical filters however, such filters restrict the response rate of the sensor as discussed above. Designers usually work hard to minimize the presence of electrical noise, but as with cyclical error, some noise will always remain. Filtering is usually a practical cure for such noise it can have minimal negative effect on the control system if the frequency content is high enough so that the filter affects only frequency ranges well above where phase lag is a concern in the application.

122 Overview of Recycling

Various devices are now commercially available to separate plastics by resin type. They typically rely on differences in the absorption or transmission of certain wavelengths of electromagnetic radiation. Many of these systems can be used to separate plastics by color as well as by resin type. For example, the process used at the plastics recovery facility in Salem, Oreg., which was developed by Magnetic Separation Systems (MSS) of Nashville, Tenn., sorts 2 to 3 bottles s, using four sensors and seven computers to separate plastic bottles according to resin and color. X-ray transmission is used to detect PVC, an infrared-light high-density array to separate clear from translucent or opaque plastics, a machine vision color sensor to identify bottle color (ignoring the label), and a near-infrared spectrum detector to identify resin type.21 Systems which use electromagnetic radiation are under development and have had limited commercial application. SRC Vision, Inc., of Medford, Oreg.,...

422 Basic fire technology

Other radiations occur as electromagnetic radiations where the transmitter emits electromagnetic waves that act directly on the molecules of a solid or liquid increasing their energy and hence raising the temperature of the material. Microwave ovens and radio frequency welding equipment emit radiations of this sort.

132 Stimulated Inelastic Scattering

The nonlinear effects governed by the third-order susceptibility X3 are elastic in the sense that no energy is exchanged between the electromagnetic field and the dielectric medium. A second class of nonlinear effects results from stimulated inelastic scattering in which the optical field transfers part of its energy to the nonlinear medium. Two important nonlinear effects in optical fibers fall in this category both of them are related to vibrational excitation modes of silica. These phenomena, known as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), were among the first nonlinear effects studied in optical fibers 18 - 20 . The main difference between the two is that optical phonons participate in SRS while acoustic phonons participate in SBS.

163 Basis for Limits of Exposure

For the establishment of limits on radiation exposure, agencies have been in existence for many years. Examples are the International Commission on Radiological Protection (ICRP), and the National Council on Radiation Protection and Measurements (NCRP). Their general procedure is to study data on the effects of radiation and to arrive at practical limits that take account of both risk and benefit of using nuclear equipment and processes. There have been many studies of the effect of radiation on animals other than man, starting with early observations of genetic effects on fruit flies. Small mammals such as mice provide a great deal of data rapidly. Since controlled experiments on man are unacceptable, most of the available information on somatic effects comes from improper practices or accidents. Data are available, for example, on the incidence of sickness and death from exposure of workers who painted radium on luminous-dial watches or of doctors who used X-rays without proper...

344 Perceptually Uniform Color Space

The hue which is essentially the chromatic component of our perception may again be considered as weak hue or strong hue. The colorfulness of a color is described by the saturation component. For example, the color from a single monochromatic source of light, which produces colors of a single wavelength only, is highly saturated, while the the colors comprising hues of different wavelengths have little chroma and have less saturation. The gray colors do not have any hues and hence they are zero saturation or unsaturated. Saturation is thus a measure of colorfulness or whiteness in the color perceived. The lightness (L) or intensity (I) or value (I ) essentially provides a measure of the brightness of colors. This gives a measure of how much light is reflected from the object or how much light is emitted from a region. It is proportional to the electromagnetic energy radiated by the object. The luminosity (or intensity) essentially helps human eye to perceive color. A colorful object...

172 Sky wave propagation

A number of layers of ionized energy exist above the earth's surface. For the purpose of explaining the effects that the layers have on electromagnetic radiation it is only necessary to consider four of the layers. These are designated, with respect to the earth's surface, by letters of the alphabet D, E, Fl and F2, respectively (Figure 1.6). They exist in the ionosphere, that part of the atmosphere extending from approximately 60 km above the earth's surface to 800 km.

1340 1291 1242 1103 1144 1099 1048 997 948 Wavenumber

Icon is tetrahedrally coordinated with four bridging oxygen atoms. Even though the bond angles are distorted slightly to produce the random glassy structure, this spectrum is quite similar to that obtained from crystalline quartz, because most features in the FTIR spectrum are the result of nearest neighbor interactions. In crystalline materials the many vibrational modes can be classified by the symmetry of their motions and, while not rigorous, these assignments can be applied to the glassy material, as well. Thus the peak near 1065 cm-1 arises from the asymmetric stretching motions of the Si and O atoms relative to each other. The band near 815 cm-1 arises from bending motions, while the one near 420 cm-1 comes from a collective rocking motion. These are not the only vibrational modes for the glass, but they are the only ones that generate electric dipoles that are effective in coupling with the electromagnetic field. For example, the glass also has a symmetric stretching mode, but...

28 Hospital Medical Waste MED

The predominant means of disposing of hospital waste is incineration (almost 35 of all hospital waste is incinerated). Other means of treatment or disposal include autoclaving, sanitary landfilling, chemical disinfection, thermal inactivation, ionizing radiation, gas vapor sterilization, segregation, and bagging.

Electrical Electronic

Electromagnetic interference (EMI) or radio frequency interference (RFI) as well as static charge is the interference related to accumulated electrostatic charge in a nonconductor. As electronic products become smaller and more powerful, there is a growing need for higher shielding levels to assure their performance and guard against failure. Conductive plastics provide EMI RFI shielding by absorbing electromagnetic energy (EME) and converting it into electrical or thermal energy.

Radio Wave Propagation

The electromagnetic spectrum was described in the last chapter in terms of different bands of frequencies with certain properties. The portions of the spectrum we will be concerned with here are the radio and microwave bands which are most commonly used for communication purposes. Figure 5-2 shows the frequencies associated with these two bands and also shows how these frequencies have been further subdivided into bands Figure 5-3 shows how electromagnetic waves of certain frequencies propagate differently. These propagation characteristics and the reasons behind each are explained as follows Ground Waves. At frequencies less than a few megahertz, electromagnetic energy can interact with the material in the earth and tend to follow the contour of the earth's surface. This property allows stations to communicate over the horizon (OTH) in longer ranges than direct path stations. As we will see, however, these lower frequencies are limited in how much information they can transmit....

3411 Nonionising radiation

There are several forms of non-ionising electromagnetic radiation that may be encountered in industry16,17. They differ from y and X-rays in that they are of longer wavelength (lower energy) and do not cause ionisation in matter. They are ultraviolet (a few tens of nanometres (nm) to 400 nm wavelength), visible (400 to 700 nm) and infrared (700 nm to 1 mm) radiations in the optical region, and microwave and radiofrequency radiations and electric and magnetic fields. The ability of radiation within one of these defined regions to produce injury may depend strongly on the wavelength. Figure 3.4.4 illustrates the monitoring for non-ionising radiation around a mobile phone base station. 3.4.11.2.3 Electromagnetic fields There is no specific legislation that relates to protection from electromagnetic fields. Nonetheless, there is enabling legislation in the general area of health and safety that places a duty of care on the operators of equipment generating electromagnetic fields....