bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of biochemical networks
Authors: Kierzek Andrzej M. 
Published: April 2005

Abstract
Advances in experimental techniques of molecular biology motivate attempts to mathematically model complex biochemical reaction networks occurring in the cell. Usually, the models are so complex that they cannot be solved analytically and so computer simulations must be employed. Biochemical reaction networks may be expressed as a system of differential equations, thus allowing standard algorithms and software packages to be used in the simulation. Frequently, the lack of precise model parameters prevents quantitative studies of the system dynamics. In such cases, qualitative simulations using logical formalism or the study of flux distribution of the stationary state may be performed. The methods mentioned above are deterministic and do not take into account stochastic fluctuations resulting from the fact that biochemical processes occur in very small volumes. Various Monte Carlo approaches are used to account for the stochastic effects in the dynamics of biochemical reaction networks. Recent advances in these methods allow simulations of systems composed of reactions varying by many orders of magnitude in their rates and the number of molecules involved. Simulations explicitly incorporating positional information on the spatial clustering of membrane receptors have also been performed.
Altimeters
Authors: Eren Halit 
Published: April 2005

Abstract
Alimeters are instruments that measure altitude or elevation objects above or below a given level. There are three types of alimeters: pressure altimeters that make use of properties of atmosphere, radio and radar altimeters that are based on electromagnetic wave propagation, and optical altimeters that use optical properties of light and lasers. All these basic altimeters find extensive applications in industry, aviation, military, navigational aids, land surveying, remote sensing, recreations, and sports.

Modern barometric altimeters are manufactured mostly as integrated circuit (IC) pressure transducers. Therefore primary signal processing such as linearization, error corrections, and gain adjustment are made within the chip. Altimeters based on electromagnetic principles transmit electromagnetic energy and detects of the reflected energy from an object. An example of these altimeters is the single‐frequency radar system that broadcasts a pulsed tone signal directly downward the object and processes the returned signals with elaborate electronic circuits for high sensitivity and resolution. Altimeters based on microwave energy transmission can be used for other purposes such as imaging, scanning, mapping, oceanographic studies, and weather forecasting. Laser altimeters operate similar to the radar altimeters by processing time differences between the transmitted and received signals. Typical examples of such altimeters are the LIDAR (light detection and ranging) and the SLA (shuttle laser altimeter) and RASCAL (
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A popular system that can be used as altimeter is the Global Positioning System (GPS), which constitutes 24 satellites orbiting around Earth. Each satellite transmits electromagnetic energy carrying unique codes and information. Information picked up receivers is used to determine positions of objects in three dimensions.
Amplitude Shift Keying
Authors: Xiong Fuqin 
Published: April 2005

AbstractAmplitude shift keying (ASK) is one of the earliest and simplest digital modulations used in telecommunications. The simplest form of ASK is theON–OFFkeying (OOK). To improve bandwidth efficiency,M‐ary ASK (MASK) must be used. MASK can be coherently demodulated and noncoherently demodulated, and the former has a lower bit error probability but a more complex demodulator. The signal expression, power spectral density, block diagrams of modulators and demodulators (coherent and noncoherent), and bit error rate, are described in detail for each ASK scheme. Comparisons are made between various ASK schemes and between coherent MASK and the popular MPSK (M‐ary phase shift keying). Advanced ASK‐based modulation schemes, namely, QAM (quadrature amplitude modulation) and coherent and noncoherent ASK‐OFDM (orthogonal frequency‐division multiplexing) are also briefly described.
Antenna Accessories
Authors: Alves Plinio R. G. , Menezes Leonardo R. A. X. , Carvalho Paulo H. P. , Silva Franklin C. 
Published: April 2005

Abstract
Accessories in antennas can be seen as devices adapted to radiating or receiving electromagnetic wave structures. Their main purpose is to create means for the perfect operation of antennas. The accessories interconnect these antennas to the transmission and reception systems in an efficient and safe way. An electromagnetic coupling generally exists between the antennas and the accessories, and one can explore them to improve antenna performance. In this way, the accessories are as fundamental as the antenna proper, whose behavior is dependent on the appropriate connections.
Several kinds of accessories, are used more frequently: attenuators, baluns, chokes, coaxial (coax) lines, insulators, lightning arresters, planar structures, phase shifters, and twin‐lead devices. These components will be described in the following sections.
Antenna Compact Range
Authors: Kefauver W. Neill 
Published: April 2005

Abstract
The antenna compact ranges is a powerful tool employed to measure the performance of antennas accurately, efficiently, and with minimal facility investment. The term “compact” comes from the concept that an antenna can be measured without using a long outdoor range; hence the range is compact or small. The performance of these ranges has improved dramatically since the mid‐1970s and range designs have improved almost as rapidly as the modeling tools to design antennas since the reflector and feed designs are tied to many of the developments in high‐performance antennas.
Antenna Feeds
Authors: Bird Trevor S. 
Published: April 2005

AbstractThe term “antenna feeds” describes many types of antennas in common use today. Feeds are a means of supplying energy to (or receiving energy from) a secondary antenna, such as a reflector, lens, or beam waveguide, via a transmission line or waveguide. Everyday applications of antennas with feeds include satellite communications, radar, radio telescopes, deep‐space probes, and terrestrial microwave and millimeter‐wave radiolinks.After a brief historical introduction, the basic characteristics of antenna feeds are explained. Then specific feed types are described under four main headings, namely aperture, linear, traveling‐wave and compound antennas. The approach adopted combines a short description of physical attributes with an outline of possible applications.The class of aperture antennas is the most extensive, and details are given of various circular and rectangular waveguides and horns, self‐supporting feeds, and microstrip patches in feed applications. Linear antenna feeds such as the Yagi–Uda, logperiodic, and zigzag arrays are reviewed and properties of importance highlighted. Under the heading of traveling‐wave antennas, the antennas discussed include the dielectric rod, profiled‐slot, Vivaldi antennas, and linefeed antennas for cylindrical and spherical reflectors. Finally, the antennas covered in the compound feeds category are arrays, beam waveguides, splash plates, and dichroic reflectors.Antenna feeds are linked intrinsically with feed systems, and some examples given are diplexers, beamforming networks, and comparator networks for monopulse tracking.The article concludes with an outline of modern design methods of importance of feed antennas and some predictions of possible future developments.
Antenna Scanning Arrays
Authors: Mailloux Robert J. 
Published: April 2005

AbstractElectronic scanning arrays provide high‐gain radiated beams that can be directed to chosen spatial angles by the use of phase shifters or time‐delay units. This feature satisfies an increasing number of applications, from the military need for large arrays for ground‐based, airborne, and space‐based radars and communication systems, to the growing needs of the wireless community for much smaller, often adaptively controlled arrays. This article describes the fundamental properties and limitations of array antennas, including the parameters that constrain their gain, beamwidth, and bandwidth, and the phenomena of grating lobes. Several examples of pattern synthesis and adaptive control algorithms are presented. Last, there is a description of array architectures as appropriate to the three basic means of control, using analog, optical, and digital means of beamforming.
Antenna Radiation Patterns
Authors: Chryssomallis Michael T. , Christodoulou Christos G. 
Published: April 2005

AbstractThe radiation pattern of an antenna is one of the antenna's basic properties since it shows how the antenna distributes its energy in space. It generally consists of a number of lobes, and if it is measured far away from the antenna, it is independent of distance. It is a function of angles and can be expressed as field or power pattern. It usually can be completely specified from the patterns in two planes, perpendicular to each other, theEandHplanes, respectively. Related to the radiation pattern of an antenna, a number of important parameters exist, such as radiated power, radiation efficiency, directivity, gain and antenna polarization.The subject of this article is to provide an introduction to radiation patterns and all the related important parameters. The content is organized in four sections. Section 1 introduces several antenna patterns, giving the necessary definitions and presenting the common types. The field regions of an antenna are also pointed out. In Section 2, after the introduction of Poynting vector and radiation power density, radiation performance measures such that the beam solid angle, directivity, and gain of an antenna are defined. In Section 3, the concepts of wave and antenna polarization are discussed. Finally, in Section 4, a general case of antenna pattern calculation is considered, and numerical solutions are suggested for radiation patterns that are not available in simple closed‐form expressions.
Antennas
Authors: Christodoulou C. G. , Wahid P. F. 
Published: April 2005

AbstractThis article provides an overview of the characteristics of various antennas used in the RF/microwave region. A brief history of antennas is presented. Starting from simple wire antennas, the article goes on to describe reflector antennas, lens antennas, horn antennas, frequency‐independent antennas, conformal antennas, and reconfigurable antennas. The salient properties of each of these antennas are presented and discussed.
Antennas for Medium‐Frequency Broadcasting
Authors: Rackley Ronald , Folkert Matthew 
Published: April 2005

Abstract
Since the 1940s, there has not been significant development in the area of the antenna element itself as selfsupporting and guyed radiating towers continue to be used much as they were at that time.
New developments have principally involved auxiliary equipment used to test and monitor the antenna system and the means by which the antenna is theoretically analyzed. Digital antenna monitors are used today to accurately monitor the relative current magnitudes and phase relationships of the towers in a directional array while portable solid‐state field strength meters are used to measure radiation patterns. Advances have also been made with improved RF current meters, sampling transformers, and impedance measuring equipment. The design of medium‐frequency broadcast antennas for optimized performance has also seen tremendous advances with the introduction of numerical solutions to electromagnetic problems and nodal modeling of feeder systems made economically possible with personal computers vastly simplifying both design and implementation.
Backscatter
Authors: Ufimtsev Pyotr Ya. 
Published: April 2005

AbstractThe backscatter, or backscattering, is the scattering of waves back toward the source of the incident wave. This process substantially depends on material properties of the scattering object, its shape, size, and spatial orientation relative to the incident wave, as well as on the frequency and polarization of the incident wave. One distinguishes three frequency regions with different physical properties of scattered waves. They are quasistatic, resonance, and quasioptical regions.
Buried Object Detection
Authors: Türk Ahmet Serdar , Hocaoglu Ali Köksal 
Published: April 2005

AbstractThe subsurface detection and identification of the buried geologic and synthetic (human‐produced) structures is currently an important research area. The scope of the problem is very complex and covers a wide range in applications. One area of the research includes the detection of a large metallic gas pipe buried in a deep or small plastic mine laid just beneath the ground. The size, geometry, constitution and depth of the target object and the characteristics of the medium (wet soil, sand, etc.) can be considered as the principal parameters for the detector designs. In this article, different sensor technologies based mainly on electromagnetic, acoustics, infrared, or chemical theories are discussed.
Cellular Radio
Authors: Lee William C.Y. 
Published: April 2005

Abstract
The cellular radio system is sometimes called a mobile phone system or a car phone system. Due to the daily needs of subscribers, cellular systems have expanded considerably all over the world. This article discusses the history of cellular systems and the difficulty of deploying them in the mobile radio environment, elaborating on employing digital cellular systems, Personal Communication Services (PCS) mobile satellite systems, and the future IMT‐2000 system.
Chirality
Authors: Lakhtakia Akhlesh 
Published: April 2005

AbstractChiral media have the ability to discriminate between left‐handed and right‐handed electromagnetic fields. These media can be classified into two types: (1) isotropic chiral media and (2) structurally chiral media. The molecules of a naturally occurring isotropic chiral medium are handed, while an artificial chiral medium can be made by randomly dispersing electrically small, handed inclusions (such as springs) in an isotropic achiral host medium. The molecules or inclusions in a structurally chiral medium, such as a chiral nematic liquid crystal, are randomly positioned but have helicoidal orientational order. Structurally chiral media can also be artificially fabricated either as stacks of uniaxial laminae or using thin‐film technology. Formulations for electromagnetic fields in both classes of chiral media are succinctly presented here.
Circuit Stability
Authors: Svoboda James A. 
Published: April 2005

Abstract
Stability is a property of well‐behaved circuits and systems. Typically, stability is discussed in terms of feedback systems. Well‐established techniques, such as Nyquist plots, Bode diagrams, and root locus plots, are available for studying the stability of feedback systems. Electric circuits can be represented as feedback systems. Nyquist plots, Bode diagrams, and root locus plots can then be used to study the stability of electric circuits.
Circuit Tuning
Authors: Schaumann Rolf 
Published: April 2005

AbstractCircuit tuningrefers to the process of adjusting the values of electronic components in a circuit to ensure that the fabricated or manufactured circuit performs to specifications. In digital circuits, where signals are switched functions in the time domain and correct operation depends largely on the active devices switching all the way between theirONandOFFstates, tuning in the sense discussed in this article is rarely necessary. In analog continuous‐time circuits, however, signals are continuous functions of time and frequency so that circuit performance depends critically on the component values. Consequently, in all except the most undemanding applications with wide tolerances, correct circuit operation almost always requires some form of tuning.
Coaxial Lines And Waveguides
Authors: Karmakar Nemai Chandra , Padhi Shantanu Kumar 
Published: April 2005

AbstractIn this article we first describe the classical theory in which transmission lines are assumed to be a distributed section of series resistance and inductance, as well as shunt capacitance and conductance. This model is then evolved into the telegrapher equation, which explains the wave nature of electromagnetic energy guided by a two‐conductor transmission line. Finally, the field theory of transmission lines is used to derive coaxial transmission‐line theory.
Combline Filters
Authors: Wang Chi 
Published: April 2005

AbstractThe combline filter, which was first introduced by Matthaei in 1963, is one of the most commonly used bandpass filters in many communication systems and other microwave applications. With modern filter synthesis theory, combline filters having elliptic function frequency responses can be realized by using the nonadjacent couplings. In this article, the lumped‐element lowpass filter prototype is first presented. The equations for conversion between the lowpass prototypegvalues and the impedance/admittance inverters or coupling matrix elements are given. Matthaei's approximated design equations and procedures using Getsinger's design data for rectangular bars, and Cristal's design curves for cylindrical rods are described for design of direct‐coupled combline filters with narrow to moderate bandwidth. A compact tapped‐line input/output coupling configuration is addressed. The general filter topologies are then discussed. The commonly used cascaded triplet and cascaded quadruplet sections for creating more complicated filter structures are presented. Typical combline applications, including multiplexers, dielectric‐filled miniature combline filters, and linear phase or delay filters are presented.
Coplanar Stripline (CPS) Components
Authors: Suh Young-Ho 
Published: April 2005

AbstractCoplanar stripline (CPS) is a balanced uniplanar transmission line, consisting of two metallic conductor strips separated by a certain gap width, on a substrate. Conventional CPS does not provide bottom metallization of the substrate for ground; instead, one of the conductor strips provides electric ground of the other signal strip.This article investigates (1) CPS transmission‐line characteristics for practical circuit design and analysis using closed‐form equations; (2) CPS circuit components such as resonators, filters, and “tee” junctions; and (3) applications to antennas and wireless power transmission.Various new CPS resonators are modeled and designed and their performance investigated in terms ofQfactor or bandwidth. As applications of the proposed CPS resonators, new CPS bandpass filters are demonstrated. The design methods of bandpass filters and their lumped‐element equivalent circuits are presented. A simple CPS lowpass filter is developed using interdigital capacitors and a CPS transmission line.For CPS component measurements, two types of broadband CPS‐to‐microstrip transition are introduced. Printed dipole antenna feeding can also be easily implemented using this transition.A novel CPS tee junction using coupled CPS (CCPS) is introduced. As an application of CPS tee junction, a twin‐dipole antenna fed by microstrip‐to‐CPS tee junction is presented at Ka band. A 1×8 printed dipole phased array is developed with the twin‐dipole antenna.Finally, as a circuit application of CPS, a dual‐frequency rectenna is developed at 2.45 and 5.8 GHz. For dual‐frequency rectenna components, a dual‐frequency antenna, CPS lowpass filter, and CPS bandstop filters are developed. To achieve high RF ‐to‐DC conversion efficiencies at both frequencies, diode analyses are performed for frequency‐insensitive high conversion efficiency.
Coplanar Stripline Transitions
Authors: Simons Rainee N. 
Published: April 2005

AbstractRF and microwave circuit components can be realized with input/output ports using either balanced or unbalanced planar transmission lines. Interconnections between these components will require a balun or a transition to transform an unbalanced port to a balanced port. This article presents several baluns or transitions, that are of either the Marchand or double‐Y type.
Coupled Transmission Lines
Authors: Paul Clayton R. 
Published: April 2005

Abstract
Two transmission lines whose electromagnetic fields are coupled induce signals from one line into another. This coupling is either intentional as in directional couplers or unintentional, producing unwanted responses in the other line, which is referred to as crosstalk. This discussion of coupled transmission lines will concentrate on the analysis of coupled lines and can be used to design intentional coupling or to assess unintentional coupling as in crosstalk.
Dielectric Measurement
Authors: Bartnikas R. 
Published: April 2005

AbstractDielectric measurements are concerned with the characterization of solid, liquid, and gaseous insulating materials over a wide range of DC and AC conditions at different frequencies temperatures, field strengths, and pressures, under differing environments.Space does not permit a detailed description of all the dielectric measurement procedures and, consequently, only a cursory presentation is made.Accordingly, the presentation is necessarily confined to a concise description of the most common methods of dielectric measurement employed currently.
Dielectric Resonators
Authors: Weily Andrew R. , Esselle Karu P. , Mohan Ananda Sanagavarapu 
Published: April 2005

AbstractDielectric resonators (DRs) are versatile components that have applications in microwave filters, oscillators, antennas, and measurement techniques. They have the advantages of highQfactor, low cost, and excellent temperature stability, and enable significant miniaturization of microwave circuits. This article provides background information on the evolution and theoretical analysis of DRs while highlighting current developments in the field. Mode classifications and field distributions are discussed for lower‐order modes of cylindrical DRs, and mode charts are presented to illustrate the effect of DR aspect ratio and cavity enclosure on the mode spectrum. A simplified analysis method for calculating the resonant frequency of the TE01δmode, the one most commonly used in practice, is described in detail. Information on calculating theQfactor, the temperature coefficient, and details of typical material parameters available from manufacturers are also presented. The article concludes with information on external and interresonator coupling for DR s and methods to compute coupling factors.