The Contribution of Vessel Volume Change and Blood Resistivity Change to the Electrical Impedance Pulse

An impedance pulse, recorded noninvasively, has contributions due to both the change in blood volume of the arteries and to the change in the blood resistivity. Other researchers have tried to quantify the relative contributions and have either underestimated or overestimated the contributions since they did not simulate the physiological conditions. We have used an in vitro flow circulation system to more closely simulate the physiological conditions and quantify the two contributions. We find that the blood resistivity change contribution is strong enough (21.5 percent of the arterial volume change contribution) to change the morphology of the impedance pulse. There is, however, a phase difference between the two contributions. As a result of this, the blood resistivity change contribution to the height of the impedance pulse will be less than 5.5 percent.     

An efficient method to compute spurious end point contributions in PO solutions

A method is given to compute the spurious end point contributions in the physical optics (PO) solution for electromagnetic scattering from conducting bodies. The method is applicable to general three-dimensional structures. The only information required to use the method is the radius of curvature of the body at the shadow boundary. Thus, the method is very efficient for numerical computations. As an illustration, the method is applied to several bodies of revolution to compute the end point contributions for backscattering in the case of axial incidence. It is shown that in high frequency situations, the end point contributions obtained using the method are equal to the true end point contributions.     

Patterns in pattern recognition: 1968-1974

This paper selectively surveys contributions to major topics in pattern recognition since 1968. Representative books and surveys pattern recognition published during this period are listed. Theoretical models for automatic pattern recognition are contrasted with practical,, design methodology. Research contributions to statistical and structural pattern recognition are selectively discussed, including contributions to error estimation and the experimental design of pattern classifiers. The survey concludes with a representative set of applications of pattern recognition technology.     

Modeling of MOSFET parasitic capacitances, and their impact on circuit performance

We study layout dependent, parasitic capacitance contributions of MOSFETs with 3D simulations, and show that these contributions are for narrow and short devices comparable to intrinsic contributions. The performance of 65-nm technology is strongly affected by these components, and should therefore be modeled accurately in circuit simulations. We propose a methodology how to accurately and consistently model them in a design flow. The methodology is validated with ring oscillator measurements.     

The Role of Clinical Engineering in Health-Care Delivery

Modern health-care delivery is becoming increasingly dependent on the contributions of engineering science and technology. The important and often critical need for such technological support has resulted in the establishment of a clinical engineering role at a number of hospitals. The literature quotes numerous examples of the contributions such a capability can make to the delivery of quality patient care.     

Scattering from a finite length rod with endpoint contribution

A uniform, high frequency analysis for calculating scattering from thin, finite length cylinders is presented. The cylinder diameter is assumed to be small (on the order of a wavelength or less) so that the modal solution is valid. The total field consists of the incident field, the scattered field from the specular point, and two endpoint contributions. A thin wire tip diffraction coefficient (TDC) is developed for calculating the end point contributions. The incident fields are those of a spherical source radiating throughout space. While the specularly scattered field and end point contributions are discontinuous, these discontinuities cancel each other, resulting in a uniformly continuous total field. Good agreement is obtained between measured and calculated results.     

Correlated e-b and c-b junction burst noise

It has been found that the total burst noise current in a bipolar transistor can be due to a single source which gives rise to contributions both from the e-b and the c-b junctions. Measurements on such a transistor show that the ratio of these contributions is inverted if the transistor is inverted. A tentative physical explanation is given for the phenomenon.     

Error analysis leading to design criteria for transmission linemodel characterization of ohmic contacts

The transmission line model (TLM) is a standard method for planar specific contact resistance measurement. Although widely used, the accuracy of a measurement is typically not stated. In addition to contributions from random errors, there can be substantial contributions from systematic errors in typical TLM measurements. In this paper, we develop an analytical model for the experimental uncertainty from the fundamental TLM expressions in order to understand and calculate the uncertainty associated with the specific contact resistance and sheet resistance derived by the TLM method. The experimental uncertainties in measured resistances, together with the pad width and pad spacing, are the dominant contributions to the total uncertainty. Analytical expressions for relative random and systematic uncertainties in contact resistance and sheet resistance are developed in terms of the error contributions and the parameters of the TLM geometry. Expressions for minimum uncertainty, with associated optimum widths and sheet resistances, serve as a basis for the design of TLM structures with minimum uncertainty. The model quantifies the increase in relative uncertainty associated with decreasing contact resistance. Simulations of uncertainty under various sheet resistance, contact resistance, and pad width are implemented and uncertainties are calculated for realistic data sets     

Multiblock principal component analysis based on a combined index for semiconductor fault detection and diagnosis

The purposes of multivariate statistical process control (MSPC) are to improve process operations by quickly detecting when process abnormalities have occurred and diagnosing the sources of the process abnormalities. In the area of semiconductor manufacturing, increased yield and improved product quality result from reducing the amount of wafers produced under suboptimal operating conditions. This paper presents a complete MSPC application method that combines recent contributions to the field, including multiway principal component analysis (PCA), recursive PCA, fault detection using a combined index, and fault contributions from Hotelling's T/sup 2/ statistic. In addition, a method for determining multiblock fault contributions to the combined index is introduced. The effectiveness of the system is demonstrated using postlithography metrology data and plasma stripper processing tool data.     

Survey of some early studies of the scattering of plane waves by a sphere

This survey of the literature prior to World War II shows that the study of the scattering of plane waves by a sphere has a history in which the list of contributors includes some of the greatest names in mathematical physics from the late nineteenth and early twentieth centuries. When viewed in retrospect, this literature appears to be characterized by the appearance of papers by writers who apparently failed to appreciate the significance of the contributions made by their contemporaries and predecessors. Emphasis is placed upon the relatively unknown contributions of Clebsch, Lorenz, Nicholson, Bromwich, Proudman, Doodson, Kennedy, and White. The uncovering of the "lost" contributions of these writers serves to enrich the historical perspective against which one should view the voluminous literature which has accrued since World War II.     

Studies of the Temperature and Frequency Dependent Impedance of an Electroceramic Functional Oxide NTC Thermistor

The charge transport mechanism and the macroscopic dielectric constant in polycrystalline device materials commonly exhibit several components such as electrode‐sample interface, grain boundary and bulk contributions. In order to gain precise understanding of the functionality of polycrystalline electroceramic device materials it is essential to deconvolute these contributions. The paradigm of functional NTC thermistor ceramics based on thick film spinel manganates has been studied by temperature dependent alternating current impedance spectroscopy. Three typical relaxation phenomena were detected, which all showed a separated temperature dependence of resistivity consistent with thermally activated charge transport. The dominating grain boundary and the interface contributions exhibited distinctively different capacitance allowing clear identification. The composite nature of the dielectric properties in polycrystalline functional ceramics was emphasized, and impedance spectroscopy was shown to be a powerful tool to account for and model such behavior.     

Comments on `A physical optics correction for backscattering fromcurved surfaces' and `An efficient method to compute spurious end pointcontributions in PO solutions' [and reply]

Comments on two related papers by Gupta et al. (ibid., vol.AP-35, no.5, p.553-631, May 1987 and ibid., vol.AP-35, no.12, p.1426-35, Dec. 1987) are made. The commentor states that the usual reason for preferring physical optics (PO) over geometrical optics (GO) in application to curved surfaces is to avoid a numerical search for a specular point. The evaluation of the end-point contributions, however, also requires a numerical search, this time for the shadow boundaries. It would therefore be inconsistent to try to remove the above contributions if the PO procedure is used. Thus the entire discussion of the redundant end point contributions seems to be equally redundant. The authors address the comments and defend their work     

Backscattering from tapered resistive strips

Resistive strips have lower backscattering cross sections than perfectly conducting strips, and this is true in particular when the illumination is edge-on with the electric vector parallel to the edge. The scattering then consists of edge contributions and attention is confined to this case. Using the available expressions for the edge contributions of uniform resistive strips it is shown that the front edge scattering decreases with increasing resistivity, whereas the rear edge scattering increases. This suggests that the resistivity should be tapered from a maximum at the front to zero at the rear, and numerical results are presented for the particular case of quadratic (parabolic) tapers. Values for the front and rear edge contributions are extracted from the scattered field data, and for strips more than about a half-wavelength in width it is found that the front edge contribution is almost identical to that for a uniform resistive half-plane. An empirical expression for the rear edge contribution is also derived, and the implications of the results are examined.     

Nonlinear gain suppression in semiconductor lasers due to carrier heating

A simple model is presented for carrier heating in semiconductor lasers from which the temperature dynamics of the electron and hole distributions can be calculated. Analytical expressions for two new contributions to the nonlinear gain coefficient, in are derived, which reflect carrier heating due to stimulated emission and free carrier absorption. In typical cases, carrier heating and spectral holeburning are found to give comparable contributions to nonlinear gain suppression. The results are in good agreement with recent measurements on InGaAsP laser diodes.<>     

Contributions of intrinsic visco-elastic torques during planar index finger and wrist movements

Human hand movements have been studied for many decades, yet the role of hand biomechanics in achieving dexterity has not been fully understood. In this paper, we investigate the contributions of the intrinsic passive viscoelastic component in the hand during the coordinated wrist and hand movements. We compare the contributions of stiffness, damping, and dynamics torques under two types of joint phase movements at two speeds. The analysis of the data collected from subject studies demonstrated that the passive visco-elastic component is dominant over dynamic coupling terms. Although the exact contributions of the three torques vary under different speeds and phasic movements, the stiffness torque was the highest (at least 47%) followed by the damping torque, while the dynamics torque was the lowest (less than 11%) in all movement scenarios. Comparisons with studies involving coordinated arm movements illustrate that dominant torques in arm and hand movements are different suggesting that neural control strategies might be distinct as well.     

PT／P（VDF—TrFE）中聚合物基体对压电效应的贡献

用压力脉冲法研究了在钙掺杂ＰＴ（钛酸铅）陶瓷粉末与Ｐ（ＶＤＦ－ＴｒＦＥ）（偏氟－三氟乙烯共聚物）复合材料中ＰＴ粉末与聚合物基体对于总的压电效应的贡献。实验结果表明，在此类复合型压电材料中，聚合物基体对于整体压电性的作用是不可忽视的，而且，陶瓷粉末与聚合物基体对于整体压电性的贡献恰好是相互抵消的。     

The transient response of photoconductive camera tubes employing low-velocity scanning

The transient signal which results from the characteristics of a low-velocity electron beam and the capacitance of the scanned surface has been calculated. A very slow transient of the hyperbolic type can result if the scanned surface is stabilized at a retarding field potential. The calculations have been verified by tests on a 6198 Vidicon, which was taken as an example. For this tube, the relative contributions of the "electronic transient" and the photoconductive decay to the observed transient response were determined. They make comparable contributions to the total transient.     

Substitutional impurity in single-layer graphene: The Koster–Slater and Anderson models

The Koster–Slater and Anderson models are used to consider substitutional impurities in free-standing single-layer graphene. The density of states of graphene is described using a model (the M model). For the nitrogen and boron impurities, the occupation numbers and the parameter η which defines the fraction of delocalized electrons of the impurity are determined. In this case, experimental data are used for both determination of the model parameters and comparison with the results of theoretical estimations. The general features of the Koster–Slater and Anderson models and the differences between the two models are discussed. Specifically, it is shown that the band contributions to the occupation numbers of a nitrogen atom in both models are comparable, whereas the local contributions are substantially different: the local contributions are decisive in the Koster–Slater model and negligible in the Anderson model. The asymptotic behavior of the wave functions of a defect is considered in the Koster–Slater model, and the electron states of impurity dimers are considered in the Anderson model.     

Who Was James Clerk Maxwell and What Was and Is His Electromagnetic Theory?

The electromagnetics community makes profuse utilization of Maxwell's equations, his theory, and their applications. It is arguable that very few of us have clear ideas about what exactly Maxwell did and what kind of scientist he was. In fact, he developed many of the fundamental ideas in electrical engineering, and provided mathematical language for their exposition. His contributions to other branches of science are no less significant. He was not only one of the great scientists of the nineteenth century, but was also great for all time. To this end, the present essay starts with a brief outline of his life. It then provides a short but critical discussion of his original contributions in electromagnetics and their evolution as his electromagnetic theory. We also give a cursory review of his significant contributions in other areas of science. It is hoped that this will provide the electromagnetics-community readers with a better and more complete appreciation of James Clerk Maxwell as a scientist, as well as of his electromagnetic theory as we know now it.     

Asymptotic analysis and numerical evaluation of short pulseradiation from a point dipole in a grounded dielectric layer

In a companion paper (see ibid., p.747-54, Jun 1993) spectral options for the synthesis of the electromagnetic fields radiated into the exterior by a pulsed electric current element inside a grounded dielectric layer are presented. The exact spectral integrals, which implement these spectral alternatives, are reduced here by asymptotic methods that extract explicit approximate forms for wavefront contributions, time-domain (TD) leaky mode contributions with space-time dependent wavenumbers and frequencies, and self-consistent hybrid combinations of both. The resulting hybrid wavefront-TD-leaky-mode algorithm is explained in physical terms and tested numerically. For both TE and TM contributions, it is found that in their domain of validity, the TD leaky modes excited within the frequency spectrum of the source pulse synthesize with remarkable accuracy the highly resolved pulse train obtained by direct tracking of multiple reflected wavefronts. Of special interest is the anomalous behavior of the TM-TD leaky modes when their angular spectra are near the Brewster angle for the air-dielectric interface. The correspondingly anomalous asymptotics is explained in detail