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This is a calculation of the chordwise lift distribution, total lift, and moment on a two-dimensional wing striking a sharp-edged gust a t supersonic speed. A direct solution is established by considering a distribution of sources in a fluid at rest. An alternate method using Busemann's conical flow is also shown to be applicable. The time history of the total lift and mid-chord moment is discussed. I t is shown tha t the total lift increases with time and reaches a maximum that corresponds to the steadystate phase of the flow. The mid-chord moment goes through a maximum independent of the Mach Number if the latter value is larger than 4/7r, while this maximum can become infinite for a range of Mach Numbers between 4/TT and 1. (1) INTRODUCTION CONSIDERABLE ATTENTION has been given lately to nonstationary flow problems of wings flying at supersonic speeds. Most of the work, however, has been concerned with the aerodynamic forces on an oscillating airfoil from the standpoint of flutter analysis. The problem of the wing hitting a sharp-edged gust is of a different nature and turns out to be actually much simpler than the oscillating airfoil problems. It is shown in section 2 that it may be treated by a distribution of sources of a simple type along the chord and that the pressure distribution may be derived by elementary methods. The procedure does not introduce a moving fluid but considers a fluid at rest in which nonstationary sources are distributed in a layer of variable extent. This point of view, which is closer to acoustics than to aerodynamics, is somewhat novel and seems to present advantages of simplicity and closeness to physical reality in certain categories of problems. The pressure distribution derived by this method is applied to the calculation of the time history of lift and moment on the wing in section 3. Particular attention is given to the value of the mid-chord moment;.-which starts from zero, rises to a maximum,,and goes back to zero. The value of this maximum and related 4ata is evaluated in section 4. These results are of particular interest to the designer. The derivation of the pressure as given in section 1 is only one of the methods that may be used in this problem. As an independent check and as an illustration of the application of Busemann's method of conical flow to a nonstationary problem, an alternate derivation is given for the pressure distribution in section 4. Received August 15, 1948. * Member of Cornell Aeronautical Laboratory consulting staff. Also Professor of Applied Physical Sciences, Brown University. In a paper by Schwarz procedures used in oscillating airfoil theory are extended to the problem of a wing striking a sharp-edged gust at supersonic speed. Results for an oscillating down-wash lead to the gust problem by a Fourier integral representation. This method constitutes a considerable detour and introduces intermediate results of a transcendental nature which are actually not needed and are more complicated than the result. I t may be verified that the expression derived in the present paper for the pressure distribution is equivalent to that derived by Schwarz. He does not, however, discuss the physical aspects of the problem or derive expressions for lift and moment. (2) DERIVATION OF THE PRESSURE DISTRIBUTION The wing of chord / enters a uniform gust of upward velocity i/0 at the supersonic velocity V (Fig. 1). The velocity component normal to the wing must remain zero, and this condition is equivalent to the generation of a velocity normal to the wing which cancels the gust velocity (Fig. 2). This may also be considered as a "reflection" of the gust on the wing. Because the velocity is supersonic, the pressure distribution on. one side does not influence the pressure on the other, and therefore we need only consider the bottom side. The pressure distribution on top will be the same except for a reversal of sign. For the same reason the pressure distribution is not influenced by the trailing edge, and

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Recently there has been some interest in the cos ϕ dependent term in the expression for the tunneling current given by B. D. Josephson. In this paper we present the result of numerical calculations on this term and it is shown that although the cos ϕ term theoretically affects the ac-current in a dc-voltage biased junction the term cannot — in practice — be verified from a relative measurement of this current. In addition we consider the only experiments in which the cos ϕ term — so far — has been shown to have observable effects. Also some model calculations on I-V characteristics are mentioned.

In this paper, a new dynamical method for pyroelectric measurement is used to investigate the effect of a biasing field on the pyroelectric behavior of a single crystal of TGS held at different stabilized temperatures. The correlation technique and the use of very low noise amplifiers for our detector result in very good signal to noise ratios. With this method, we show the existence of a critical field Ecr which is necessary to move the domain walls, and a minimal field Em which is required to produce a single domain state.

I N a previous publicationi we have analyzed the reflection of a plane electromagnetic wave on a rough surface. Due to an error in sign* in Eq. (3.6) of the foregoing reference the sign on the right side of Eqs. (3.7) and (3.9) must also be changed. This amounts to replacing the “roughness parameter” r by -(r throughout the paper. In particular the boundary condition (7.8) for the case of vertical polarization should read

Superconductors are characterized by many unique properties which are all manifestations of the macroscopic quantum nature of the superconducting state. Several of these properties have direct application to devices for shielding, stabilizing, measuring and producing magnetic fields. The zero resistance property of superconductors has been used to construct magnets capable of producing magnetic fields up to 140 kgauss. This same property also provides for excellent magnetic shielding, i.e., the net magnetic flux linking a closed superconducting path must remain constant as long as the path remains superconducting. The somewhat more subtle property of quantized magnetic flux has been used in the construction of sensitive magnetometers with field resolution as good as 10-7 gauss. Tunneling of superconducting electron pairs through a non-superconducting barrier was predicted by Josephson in 1962 and verified experimentally the following year by Rowell. Various extensions of the Josephson tunneling properties of superconductors have remarkable device applications. In particular the tunneling characteristics are changed appreciably by external magnetic fields. Magnetometers using this property have been used to resolve field changes as small as 10-10 gauss. The application of these properties of superconductivity, especially to sensitive magnetometry, will be reviewed to lay the groundwork for the more detailed papers to follow in this session. All of the devices noted above require temperatures near 4 °K in order to function. This is a particularly significant requirement for space instruments and for many earth-based geophysical measurements as well. Liquid helium refill systems are the simplest cooling techniques, although serious logistic and handling problems may be encountered in field applications. Closed cycle miniature refrigerators could make superconducting magnetometers, shields, etc., practical field instruments. The present state of the art in all of these cooling techniques will be reviewed.

This paper addresses a puzzle: how to account for changes in the routine behavior of groups, organizations and individuals in Britain? Following a detailed analysis of state-market interdependence and the role of the state in creating the market, an analysis drawn from the thinking of Weber and Polanyi, we suggest adapting Weber's notion of bureaucratic revolution: in what we call the British bureaucratic revolution, the state has played an essential role in social change by creating institutions and rules that are lastingly reorienting actors' behavior. The example of the healthcare field is examined in order to identify the specific mechanisms that have been impacting on behavior within an approximately ten-year period; namely, the introduction of 1) competitive practices (sanction/reward) and 2) auditing and inspection. If this interpretation is valid, then it is reasonable to assume that the effects of this bureaucratic revolution extend beyond Britain. This article is a response to a phenomenon we initially found surprising and that we have now defined as a puzzle. Having studied change in British society over the last twenty years, we, like others, have observed a radical transformation of the behavior of individuals, groups and organizations. How is it that union leaders steeped in Labour Party traditions have begun competing with each other more intensively by trying to offer their members

This paper discusses the applicability of statistics to a wide field of problems. Examples of simple and complex distributions are given.

A significant factor which affects the accurate prediction of the discharge coefficients of square edged orifice plates is the precise shape of the edge. A rounding of only 0·002 of the orifice diameter can increase the coefficient by 1% so that a reliable method of assessing the edge sharpness is of considerable benefit to the instrument engineer. In the work described in this paper, a systematic intercomparison of three methods of measuring orifice edge sharpness has been undertaken. The methods tested involved casting, lead foil impression and optical techniques, and their relative reliability and effectiveness has been assessed. While the results obtained from the casting and lead foil methods showed good agreement, the foils did not follow the edge profiles as closely as the castings. The casting procedure can also be used to determine the shapes of re-entrant profiles which will not be detected using lead foil impressions. However, the casting method required more skill and considerably more time to complete measurements than the impression method. The optical method proved to be the least reliable, since measurements depended on subjective judgment. Nevertheless, this measuring procedure could be completed more quickly than the others, and these tests indicated that it may be used to examine large diameter plates for burrs or excessive rounding.

This paper extends the usefulness of an earlier report by evaluating an approximation for the transient response. The approximation examined is that of equivalent oil column stiffness; this has been used in the past, without evaluation, for displacement but is extended here to cover pressure transients. The comparisons between approximate and correct displacement responses indicate that the former is of sufficient accuracy for most practical purposes. In the two very different cases investigated, the approximation gives conservative estimates of the pressure peak.

The aim of the work presented here is to enlarge the subset of VHDL which can be manipulated by formal verification tools by including the timing constructs. In this paper we give formal semantics for these constructs. And, we prove, partially, the equivalence between these semantics and the informal operational semantics of the language as defined in the VHDL language reference manual. Also, we show how these semantics can establish a basis for the construction of formal timing verifiers.

The paper first offers a parallel between two approaches to conceptual clustering, namely formal concept analysis (augmented with the introduction of new operators) and bipartite graph analysis. It is shown that a formal concept (as defined in formal concept analysis) corresponds to the idea of a maximal bi-clique, while sub-contexts, which correspond to independent "conceptual worlds" that can be characterized by means of the new operators introduced, are disconnected sub-graphs in a bipartite graph. The parallel between formal concept analysis and bipartite graph analysis is further exploited by considering "approximation" methods on both sides. It leads to suggest new ideas for providing simplified views of datasets, taking also inspiration from the search for approximate itemsets in data mining (with relaxed requirements), and the detection of communities in hierarchical small worlds. © 2013 Copyright the authors.

This paper describes a procedure for simulation of digital control systems on an analog computer with digital logic. The digital elements are only those normally provided in the digital panel now available as an optional accessory from most analog computer manufacturers. When used in conjunction with the conventional analog amplifiers and integrators connected as track-hold devices, it is possible to simulate complete systems which include not only the straightforward single-rate system but also those having two or more sampling rates or subsystems, and those having delayed or skip sampling characteristics. The digital logic connections for some simple but typical problems are given and are suggestive of those required for more sophisticated applications. A couple of oscilloscope photographs are included which show the informative presentation which can be obtained with this simulation technique.

The elementary theory of the bending of a beam on an elastic foundation is based on the assumption that the beam is resting on a continuously distributed set of springs the stiffness of which is defined by a “modulus of the foundation” k. Very seldom, however, does it happen that the foundation is actually constituted this way. Generally, the foundation is an elastic continuum characterized by two elastic constants, a modulus of elasticity E, and a Poisson ratio ν. The problem of the bending of a beam resting on such a foundation has been approached already by various authors. The author attempts to give in this paper a more exact solution of one aspect of this problem, i.e., the case of an infinite beam under a concentrated load. A notable difference exists between the results obtained from the assumptions of a two-dimensional foundation and of a three-dimensional foundation. Bending-moment and deflection curves for the two-dimensional case are shown in Figs. 4 and 5. A value of the modulus k is given for both cases by which the elementary theory can be used and leads to results which are fairly acceptable. These values depend on the stiffness of the beam and on the elasticity of the foundation.

The coupled oscillations of a flexible propeller and an aircraft engine with arbitrary number of cranks is investigated. In the first part of this paper a practical method is developed to determine the complete dynamical characteristics of a rotating vibrating propeller of arbitrary shape, and the legitimacy of the approximations is checked with a numerical example. In the second part the first nine torsional frequencies of a V-12 engine, with a flexible propeller are calculated and compared to the frequencies of the free-wheeling propeller and those obtained by considering the propeller as rigid. The simultaneous influence of the engine speed on all nine frequencies and the general procedure to compute the complete critical speed spectrum are also indicated.

International audience; This paper presents an overview of a comprehensive collection of on-line testing techniques for VLSI. Such techniques are for instance: self-checking design, allowing high quality concurrent checking by means of hardware cost drastically lower than duplication; signature monitoring, allowing low cost concurrent error detection for FSMs; on-line monitoring of reliability relevant parameters such as current, temperature, abnormal delay, signal activity during steady state, radiation dose, clock waveforms, etc.; exploitation of standard BIST, or implementation of BIST techniques specific to on-line testing (Transparent BIST, Built-In Concurrent Self-Test, ...); exploitation of scan paths to transfer internal states for performing various tasks for on-line testing or fault tolerance; fail-safe techniques for VLSI, avoiding complex fail-safe interfaces using discrete components; radiation hardened designs, avoiding expensive fabrication process such as SOI, etc.

The fitting of mathematical models to physiological sys tems can be tedious and difficult, whether one uses analog or digital computer methods. Both methods have their pros and cons depending on the available hardware and software and on the type of modeling. In recent years many digital simulation languages have been written com bining analog-like and digital features to facilitate model ing, but, for a variety of reasons, none of these was suit able for our applications. We, therefore, designed a new digital simulation control system, SIMCON, which is de scribed in this paper. The primary objectives were to provide: (1) Maximum man-machine interaction at run-time, in cluding visual displays, digital control, and both con tinuous analog and digital parameter adjustment (2) The ability to generate solutions and to fit them to experimental data or other theoretical curves with a minimum of computer memory (3) The option to use a mathematically oriented language, FORTRAN, and block operators with variable input/ output. The result is a relatively general and simple simulation system which is easy to use and has wide versatility.

2014 The analysis of the experimental data on optical absorption, reflection and photoconductivity of cadmium telluride indicates a considerable contribution of exciton absorption and the process of exciton diffusion from the surface region into the volume with subsequent dissociation. The lifetimes of excess carriers are of the order of 10-8 10-9 s both at weak and intensive excitation. The data on p-n junctions in CdTe are presented. REVUE DE PHYSIQUE APPLIQUEE TUME 1, SEPTEMBRE 19GG, PAGE Several years ago Yu. Maslakovets et al. in Leningrad have shown that CdTe photocells made by surface-barrier technique are promising for the purposes of solar energy conversion (1). However, the difficulties of crystal growing and uncertain data en absorption mechanism, carriers’ lifetime and mobilities have slowed down the progress of CdTe photocell utilization. Optical absorption near the fundamental band edge in cadmium telluride crystals was studied by Davies and Shilliday [1] and Dubrovsky [2]. The results of the mentioned works do not agree. The authors of [1] come to the conclusion that near the fundamental band edge the absorption is due both to direct and indirect transitions. According to [1] the absorption in the indirect region reaches 103 cm-1. On the other hand, according to Dubrovsky’s work, the intrinsic absorption is due only to indirect transitions. The resulis of electrical measurements and luminescence spectra [3] and the data on cyclotron resonance [4] indicate that in CdTe crystals the main part of absorption must be connected with the direct transitions. Marple and Segall, who studied the optical absorption in very pure cadmium telluride, came to the same conclusion [5]. The CdTe crystals used in the present work were grown by S. A. Medvedev and S. N. Maximovsky. The spectra of photoconductivity, absorption and reflexion were studied at liquid nitrogen or helium temperatures (2). The samples have p-type conduc(1) Yu. Maslakovets and oth., J. of Tech. Phys., USSR, 1957, 27, 1594. (2) The methods of measurements will be given in detail in a paper submitted to Fizika Tverdovo Tela. FIG. 1. The photoconductivity of a CdTe sample with ground surface (curve 1) and strongly etched surface (curve 2) at 80 °K. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/rphysap:0196600103021700