边界扫描测试在数字电路自动测试系统中的研究与应用[BT)]

边界扫描测试是当前数字电路模块故障隔离的主要手段,但测试能力受到模块可测试性设计限制,其它方面作用也被忽略。文中对数字电路自动测试系统设计提出了边界扫描测试应用技术,包括系统自检测试,模块功能测试和模块故障隔离。在系统自检测试中应用边界扫描,提高了设备自检故障隔离精度;而对于模块功能测试,边界扫描测试技术提供了一种新的选择;在故障隔离中扩展和延伸应用边界扫描技术,突破了模块自身测试性的限制,提高了边界扫描测试的故障覆盖率和故障隔离精度。通过实际测试验证表明,该设计方法稳定可靠,同时提升了测试系统自身和模块的测试能力和隔离精度。     

Effects of the use of personal music players on amplitude modulation detection and frequency discrimination

Measures of auditory performance were compared for an experimental group who listened regularly to music via personal music players (PMP) and a control group who did not. Absolute thresholds were similar for the two groups for frequencies up to 2 kHz, but the experimental group had slightly but significantly higher thresholds at higher frequencies. Thresholds for the frequency discrimination of pure tones were measured for a sensation level (SL) of 20 dB and center frequencies of 0.25, 0.5, 1, 2, 3, 4, 5, 6, and 8 kHz. Thresholds were significantly higher (worse) for the experimental than for the control group for frequencies from 3 to 8 kHz, but not for lower frequencies. Thresholds for detecting sinusoidal amplitude modulation (AM) were measured for SLs of 10 and 20 dB, using four carrier frequencies 0.5, 3, 4, and 6 kHz, and three modulation frequencies 4, 16, and 50 Hz. Thresholds were significantly lower (better) for the experimental than for the control group for the 4- and 6-kHz carriers, but not for the other carriers. It is concluded that listening to music via PMP can have subtle effects on frequency discrimination and AM detection.     

Optimisation of damping treatments based on big bang–big crunch and modal strain energy methods

A cost-effective methodology is needed in various applications in order to optimise damping treatments for structures. Although some methods appear to be applicable for structures with relatively simple geometries, it is still difficult to utilise them for general structures. This paper presents an efficient approach for optimisation of passive damping treatments that can be applied to general structures. First, an optimisation procedure based on big bang–big crunch optimisation method is introduced and its effectiveness for damping optimisation is evaluated. Then, a procedure based on modal strain energy method is presented for the prediction of modal damping levels for structures with damping treatments and its performance is assessed. After that, for validation purposes, the proposed optimisation methodology is used to maximise modal damping for a single mode of a structure whose optimised configurations are known for the individual modes. Finally, the performance of the proposed optimisation procedure is demonstrated for the maximisation of damping levels for multiple modes at the same time and the applicability of the approach for general structures with passive damping treatments is demonstrated.     

Increasing the performance of tritium analysis by electrolytic enrichment†

Several improvements are described for the existing tritium enrichment system at the Isotope Hydrology Laboratory of the International Atomic Energy Agency for processing natural water samples. The improvements include a simple method for pretreatment of electrolytic cells to ensure a high tritium separation factor, an improved design of the exhaust system for explosive gases, and a vacuum distillation line for faster initial preparation of water samples for electrolytic enrichment and for tritium analysis. Achievements included the reduction of variation of individual enrichment parameters of all cells to less than 1% and an improvement of 50% of the stability of the background mean. It resulted in an improved detection limit of less than 0.4 TU (at 2s), important for application of tritium measurements in the future at low concentration levels, and resulted in measurement precisions of±0.2 TU and±0.15 TU for liquid scintillation counting and for gas proportional counting, respectively.     

Numerical procedures for natural gas accurate thermodynamic properties calculation

Natural gas (NG) is a mixture of 21 elements and widely used in the industries and domestics. Knowledge of its thermodynamic properties is essential for designing appropriate process and equipments. In this study, the detailed numerical procedures for computing most thermodynamic properties of natural gas are discussed based on the AGA8 equation of state (EOS) and thermodynamics relationships. To validate the procedures, the numerical values are compared with available measured values. The validations show that the average absolute percent deviation (AAPD) for density calculations is 0.0831%, for heat capacity at the constant pressure is 0.87%, for heat capacity at the constant volume is 1.13%, for Joule-Thomson coefficient is 1.93%, for speed of sound is 0.133%, and for enthalpy is 1.06%. Furthermore, in this work, the new procedures are presented for computing the entropy and internal energy. Due to lack of experimental data for these properties, the validation is done for pure methane. The validation shows that AAPD is 0.078% and 0.0133% for internal energy and entropy, respectively.     

Normal modes and quality factors of spherical dielectric resonators: I — shielded dielectric sphere

Electromagnetic theoretic analysis of shielded homogeneous and isotropic dielectric spheres has been made. Characteristic equations for the TE and TM modes have been derived. Dielectric spheres of radii of the order of μm size are found suitable for the optical frequency region whereas for the microwave region radii of the order of mm size are found suitable. Parameters suitable for their application in the optical and microwave frequency ranges have been used to compute the frequencies corresponding to the normal modes for the TE and TM modes. Expressions for the quality factors for realistic resonators, i.e., for a dielectric sphere with a non-zero conductivity and a metal shield with a finite conductivity have also been derived for the TE and TM modes. Computations of the quality factors have been made for resonators with parameters suitable for the optical and the microwave regions.     

Calculation of the luminescence of a finite volume with population inversion

Amplified luminescence is examined for a polished cylindrical rod. Nonlinear transport equations are used to examine the distribution of the emission along the rod and the mean density of the amplified luminescence. It is found that the probability of luminescence-induced transitions is of the same order as that for spontaneous transitions for a ruby rod. Calculations are presented for storage in a metastable level and for oscillation. Estimates are presented for the amplified luminescence from a cylinder with nonreflecting surfaces and also for a sphere.I am indebted to B. I. Stepanov for interest and valuable advice.     

Magnetoreflection studies of graphite intercalation compounds

Magnetoreflection spectra are presented for the first time for donor graphite intercalation compounds and for acceptor compounds of low stage. Analysis of these spectra yields values for the K-point effective masses for the conduction and valence bands. Shifts in Fermi level are determined and a breakdown in selection rules for K-point transitions is reported.     

Application of the Scherer-Blume theory to the intermediate ionization regime

Blume's formula for the time-differential attenuation coefficients for the hyperfine perturbation of ions recoiling in gas is rewritten in a form convenient for numerical solution when the number of precession frequencies is large. Asymptotic expressions for the behaviour of the solutions for very short, and very long correlation time are given. Approximate condition for the existence of a minimum in the pressure dependence of the time differential coefficients, as well as the position and depth of such a minimum, are also derived, and compared with the results of calculations for various physical systems.Supported in part by the Israel Commission for Basic Research.     

Surface plasma waves in silver and gold

The dispersion curves for surface plasma waves (SPW) in Ag have been determined from calculated reflectivity minima as exhibited by attenuated total reflection (ATR spectra) for the prism-air-metal (PAM) configuration and from the direct calculation of the dispersion relation for the same configuration. The dispersion curves for Au have been determined by measuring the ATR spectra for the prism-dielectric-metal (PDM) configuration, by calculating the ATR spectra from published optical constants and from the direct calculation of the despersion relation for the PDM configuration. We have found two general types of solutions from the direct calculation of the dispersion relation for both configurations. The two solutions are the surface or Brewster modes and the virtual modes. The characteristics of both modes are discussed. The effect of electronic damping upon the dispersion curves for Ag which exhibits low electronic damping and Au which exhibits moderate electronic damping is demonstrated. Finally the perturbing effect of the dielectric (referred herein as dielectric shift) upon the displacement of the dispersion curves to higher wave number for the PAM configuration for Ag and for the PDM configuration for Au is shown.     

Feynman integral and perturbation theory in quantum tomography

We present a definition for tomographic Feynman path integral as representation for quantum tomograms via Feynman path integral in the phase space. The proposed representation is the potential basis for investigation of Path Integral Monte Carlo numerical methods with quantum tomograms. Tomographic Feynman path integral is a representation of solution of initial problem for evolution equation for tomograms. The perturbation theory for quantum tomograms is constructed.     

Effect of field polarizations on recoil resonances

The effect field polarization has on the amplitude of recoil-induced resonances is considered for laser-cooled free atoms and for atoms in an operating magneto-optical trap. Explicit analytical expressions for the polarization dependence of resonance amplitudes in perturbation theory are obtained for all closed dipole transitions. Optimum conditions of polarization are found for the observation of resonances.     

Second-harmonic generation of polarization singularities

Second-harmonic generation was studied theoretically for the vector singularities (daisy modes) of linearly polarized light and for the elliptic singularities (C points) of elliptically polarized light. Topological charge doubling for C points and daisy modes, similar to that found for vortices, was found. Unlike for vortices, however, it was found that for both C points and daisy modes the sign of the charge is reversed; for C points the photon spin or handedness (right or left) is also reversed; and for daisy modes the number of intensity petals is not doubled. These findings are all unexpected because neither charge nor spin nor orbital angular momentum is conserved for C points, whereas a daisy mode in which the number of intensity petals does not equal twice the magnitude of the charge is anomalous.     

Resonance absorption band model

A model is derived for the resonance absorption of molecular bands composed of Lorentzian lines that is suitable for calculating fluorescence from irradiated air. The model is based on an explicit functional form derived for the resonance absorption of a single Lorentzian line which properly accounts for the possibility of unequal emission and absorption line widths. A procedure for rapid numerical computation of this function is given. This function yields a model for the resonance absorption of molecular bands composed of either overlapping or separated lines. A significant savings in computation time is obtained by using the model in place of exact expressions for resonance absorption. Examples are given for the resonance absorption of the N₂⁺ First Negative band system.     

Hydrogen defect-level pinning in semiconductors: the muonium equivalent

We have determined locations for the donor and acceptor levels of muonium in six semiconductor materials (Si, Ge, GaAs, GaP, ZnSe, and 6H-SiC) as a test of defect-level pinning for hydrogen. Within theoretical band alignments, our results indicate a common energy for the equilibrium charge-transition level Mu(+/-) to within experimental uncertainties. However, this is nearly 0.5 eV higher than the energy at which the equivalent level for hydrogen was predicted to be pinned. Corrections for zero-point energy account for only about 10% of this difference. We also report experimental results for the (negative-U) difference between donor and acceptor levels for Mu to be compared with calculated values for H impurities in the same materials.     

Linear theory of ionization cooling in 6D phase space

A linear theory is developed for ionization cooling of muon beams in periodic channels that can provide cooling of the transverse emittances and also of the longitudinal emittance via emittance exchange. The channels incorporate solenoids and quadrupoles for transverse focusing, dipoles to generate dispersion, wedged absorbers for ionization, and rf cavities for acceleration. The beam evolution near equilibrium is described by coupled first-order differential equations for five generalized emittances with two excitation sources. The results should be useful for understanding the cooling process and for designing cooling channels of future muon colliders and neutrino factories.     

Effects of roving level and spectral range on vowel formant discrimination

Thresholds of vowel formant discrimination for F1 and F2 of isolated vowels with full and partial vowel spectra were measured for normal-hearing listeners at fixed and roving speech levels. Performance of formant discrimination was significantly better for fixed levels than for roving levels with both full and partial spectra. The effect of vowel spectral range was present only for roving levels, but not for fixed levels. These results, consistent with studies of profile analysis, indicated different perceptual mechanisms for listeners to discriminate vowel formant frequency at fixed and roving levels.