General Experimental Method Research Articles

Surface/Interface X-Ray Diffraction

Abstract The structural challenges presented by the two-dimensional (2D) world of surfaces and interfaces have proven formidable. In spite of the critical role that they play in such diverse sciences as catalysis, tribology, metallurgy, and electronic devices and in spite of the expected richness of two-dimensional physics of melting, magnetism, and related phase transitions, only a few surface structures are known and most of those only semiquantitatively (e.g., their symmetry). Our inability in many cases to understand atomic structure and to make the structure/properties connection in the 2D region of surfaces and interfaces has significantly inhibited progress in understanding this rich area of science. Furthermore, the synthesis of new materials has played a key role in modern industrial evolution, and this synthesis is also the foundation of contemporary materials research. Many of the new materials fabrication processes are based on crystal growth and thin film deposition techniques, such as molecular beam epitaxy (MBE), chemical vapor deposition (CVD), liquid phase epitaxy (LPE), sputtering deposition, laser ablation and electrochemical plating. To improve the development and engineering of materials based on these techniques, it is essential to have a detailed understanding of the fundamental interactions and effects pertaining to the basic surface and interface structures. This knowledge will allow scientists and engineers to predict and control material properties based on the processing parameters and resulting configurations. This knowledge will be useful also for the understanding of modern composites, ceramics, and nanophase materials in which surfaces and interfaces play a large role in determining their physical and chemical characteristics. With the advent of high-brilliance synchrotron radiation sources and improved analytical methods, surface-sensitive X-ray techniques have recently been developed to study the structure and the associated reactions/transformations at surfaces and interfaces. These synchrotron X-ray techniques have already proven to be a powerful tool to probe surfaces/interfaces beyond the capabilities of earlier experimental methods involving electrons, ions, neutrons and light. This paper will discuss the general principles and experimental method of surface/interface X-ray diffraction as well as provide several examples to demonstrate the usefulness of the techniques applied to surface/interface problems.

Determination of electron polytropic indices in the environment of comet P/Halley

We present a general experimental method to investigate the relations between the density variations and the pressure variations (parallel and perpendicular to the ambient magnetic field) for one particle population of a hot collisionless plasma. The theoretical aspects of this problem have already been discussed in a recent paper [Belmont and Mazelle, 1992]. The aim of this letter is to provide a complete description of the data analysis technique for an experimental case, from GIOTTO electron and magnetic field data measured in the environment of comet P/Halley, used to verify the theory. The correlations between the electron characteristics, density and pressures (parallel and perpendicular), and the magnetic field strength are investigated. In this case, the method shows that the relations between the electron density and pressures can be satisfactorily represented by two polytropic laws. The values inferred for the polytropic indices strongly differ from those usually found in the literature, but are nevertheless fully quantitatively explained from the theoretical analytical calculations.

General experimental method of parameter extraction for CMOS timing macromodels

A new general experimental method for timing macromodel parameter extraction is proposed and investigated. Based on the general timing models developed and the measured timing data of CMOS inverters, the critical field exponent UEXP of carrier mobilities in transient operation, the optimal gate/source voltage and pn-junction voltage, and the capacitances associated with a logic gate are extracted by using the proposed method. It is shown that the extracted value of UEXP is twice the conventional value owing to the integration effect on the drain currents in delay calculations. The optimal linearisation gate/source voltage is about 0.7 VDD, whereas the pn-junction voltage is approximately VDD/2. By using the extracted timing parameters, the accuracy of the timing macromodels developed is improved and experimentally verified. The possibility of accuracy improvement and experimental verification makes the proposed method quite helpful in developing efficient timing macromodels for digital VLSI.

A method for determining energy gap narrowing in highly doped semiconductors

A general experimental method for the determination of the phenomenological energy gap narrowing \DeltaE_{G} in regions of semiconductor devices that have high concentrations of donor or acceptor impurity atoms is presented. The theoretical grounds for the method are discussed in detail, including the strong influence of Fermi-Dirac statistics on minority-carrier recombination in heavily doped regions. The method requires measurements only of the temperature dependence of de current; therefore it is very accurate. The values of \DeltaE_{G} deduced from the method are insensitive to the mechanisms controlling recombination and to the value of minority-carrier mobility in the heavily doped region; they are also independent of the value of n i the intrinsic carrier density, at a specific temperature. The values for the Si:As emitters of transistors and diodes were measured in the majority-carrier concentration range from 4 × 1018cm-3to 2 × 1020cm-3.

A field and circuit thermodynamics for integrative physiology. III. Keeping the books--a general experimental method.

ARTICLESA field and circuit thermodynamics for integrative physiology. III. Keeping the books--a general experimental methodA. S. IberallA. S. IberallPublished Online:01 Mar 1978https://doi.org/10.1152/ajpregu.1978.234.3.R85MoreSectionsPDF (4 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByNovel molecular insights into ATP synthesis in oxidative phosphorylation based on the principle of least actionChemical Physics Letters, Vol. 796Inadequacies of the Computer MetaphorA Dynamical Basis for Action SystemsChapter IVa An Ecological Approach to Perception and ActionWhat muscle variable(s) does the nervous system control in limb movements?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4A speech-motor-system perspective on nervous-system-control variables4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Servos and regulators in the control of leg muscles4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4The stick insect as a model for muscle control4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Force as the controlling muscle variable in limb movement4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Are position-control systems active during leg movement of walking arthropods?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Does control of limb movement equal control of limb muscles?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Are whole muscles the fundamental substrate for the CNS control of movement?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Voluntary control of muscle length and tension, independently controlled variables, and invariant length–tension curves4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Control theoretic concepts and motor control4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Do force-measuring sense organs contribute to the reflex control of motor output in insects?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Multiple roles of muscular afferents4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Force and stiffness: Further considerations4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Central control and reflex regulation of mechanical impedance: The basis for a unified motor-control scheme4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Moving with control: Using control theory to understand motor behavior4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Respective roles of reflex-gain control and reprogramming in adaptive motor control4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4The role of proprioceptors and the adaptive control of limb movement4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4The CNS as a multivariable control system4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Systems analysis in the study of the motor-control system: Control theory alone is insufficient4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Motor control: Which themes do we orchestrate?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4The motor system controls what it senses4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4How modest is the gain of the stretch reflex?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Tonic stretch reflex during voluntary activity4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Reflex action in the context of motor control4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4How was movement controlled before Newton?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4The importance of connective tissue within and between muscles4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Control of limb movement without feedback from muscle afferents4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Movement control: Signal or strategy?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Neurological ballistic movements: Sampled data or intermittent open-loop control4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Motor equivalence and distributed control: Evidence for nonspecific muscle commands4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Reductionism cannot answer questions of movement control4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Must the nervous system be limited to afferent variables in the control of limb movement?4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Movement control views: From diversity to unity4 February 2010 | Behavioral and Brain Sciences, Vol. 5, No. 4Systems Analysis of Hormone ActionPatterns of Human Interlimb Coordination Emerge from the Properties of Non-Linear, Limit Cycle Oscillatory ProcessesJournal of Motor Behavior, Vol. 13, No. 4 More from this issue > Volume 234Issue 3March 1978Pages R85-R97 Copyright & PermissionsCopyright © 1978 the American Physiological Societyhttps://doi.org/10.1152/ajpregu.1978.234.3.R85PubMed629372History Published online 1 March 1978 Published in print 1 March 1978 Metrics

Gridwork Rigidity Determined by Interferometry

An experimental method based on optical interferometry is applied to find the deflected shape of gridworks subjected to lateral loads These experimental results are compared with results obtained by moment distribution calculations and by the use of the equivalent elastic constants of Horvay and Malkin The technique itself, which has been developed by one of the authors as a general experimental method of studying the flexure of thin elastic plates, has been described in the accompanying paper

The Correlation of Metrical Properties of a Physical System

A Physical ' system comprises a restricted region of the world which is the subject of investigation in terms of certain designated variables that are considered as metrical properties of that system. To decide just what variables are relevant to the problem of describing a particular system requires an insight for which no universal rules of procedure can possibly be given, but once having chosen at least two variables, x and y, the specification of the system can be made in terms of a functional relationship between them, a y = f(x) or (x,y) = 0. It will be shown that a functional relation can be developed which expresses a number of the important aspects of the general experimental method that aims to establish the actual form of the relationship between the designated variables.

Discussion on “A general experimental method to determine the properties of artificial media at centimetre wavelengths, applied to an array of parallel metallic plates”

Discussion on “A general experimental method to determine the properties of artificial media at centimetre wavelengths, applied to an array of parallel metallic plates”

A general experimental method to determine the properties of artificial media at centimetre wavelengths, applied to an array of parallel metallic plates

This paper describes measurements at centimetre wavelengths (8.0–11.0cm) on a system representing a semi-infinite array of infinitely thin, perfectly conducting, metallic plates. The purpose is to illustrate a general experimental method of determining the properties of such artificial media. The parallel-plate system was chosen since, in addition to exhibiting the interface phenomena peculiar to artificial media, it is the only one for which a rigorous solution is known. The measurements were made using a parallel-strip transmission-line1 specially developed for the study of two-dimensional structures which are non-uniform transverse to the direction of propagation.

CHAPTER 3:General experimental method and nature of material

Acta Medica ScandinavicaVolume 121, Issue S160 p. 49-53 CHAPTER 3:General experimental method and nature of material First published: January/December 1945 https://doi.org/10.1111/j.0954-6820.1945.tb18972.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume121, IssueS160January/December 1945Pages 49-53 RelatedInformation

Appendix.―Filtration experiments with virus of infectious ectromelia

The primary demand upon any filtration method, as an adjunct to microscopical studies, is that it should provide a means of fractionating from a polydisperse system particles which within certain limits are of a definite order of size. To accomplish this it is essential to have a series of graded filters of known porosities, capable of being reproduced with constancy. Then, by adopting a carefully regulated filtration technique, graded filtrates can be obtained, the particle size of dispersed material in any one of which is determined by the grade of filter employed. The use of such a method in conjunction with microscopical examination of filtrates provides at once a direct method for the analysis of disperse systems. This, of course, assumes that the disperse phase is resolvable by the optical methods available. Mr. Barnard has already indicated briefly the part played by filtration in the present study on the virus of infectious ectromelia. I propose to describe in more detail the lines along which the filtration experiments have been conducted, and particularly the steps in the development of the general experimental method.