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。     

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.     

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.     

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.     

Pitch discrimination and phase sensitivity in young and elderly subjects and its relationship to frequency selectivity.

Frequency difference limens for pure tones (DLFs) and for complex tones (DLCs) were measured for four groups of subjects: young normal hearing, young hearing impaired, elderly with near-normal hearing, and elderly hearing impaired. The auditory filters of the subjects had been measured in earlier experiments using the notched-noise method, for center frequencies (fc) of 100, 200, 400, and 800 Hz. The DLFs for both impaired groups were higher than for the young normal group at all fc's (50-4000 Hz). The DLFs at a given fc were generally only weakly correlated with the sharpness of the auditory filter at that fc, and some subjects with broad filters had near-normal DLFs at low frequencies. Some subjects in the elderly normal group had very large DLFs at low frequencies in spite of near-normal auditory filters. These results suggest a partial dissociation of frequency selectivity and frequency discrimination of pure tones. The DLCs for the two impaired groups were higher than those for the young normal group at all fundamental frequencies (fo) tested (50, 100, 200, and 400 Hz); the DLCs for the elderly normal group were intermediate. At fo = 50 Hz, DLCs for a complex tone containing only low harmonics (1-5) were markedly higher than for complex tones containing higher harmonics, for all subject groups, suggesting that pitch was conveyed largely by the higher, unresolved harmonics. For the elderly impaired group, and some subjects in the elderly normal group, DLCs were larger for a complex tone with lower harmonics (1-12) than for tones without lower harmonics (4-12 and 6-12) for fo's up to 200 Hz. Some elderly normal subjects had markedly larger-than-normal DLCs in spite of near-normal auditory filters. The DLCs tended to be larger for complexes with components added in alternating sine/cosine phase than for complexes with components added in cosine phase. Phase effects were significant for all groups, but were small for the young normal group. The results are not consistent with place-based models of the pitch perception of complex tones; rather, they suggest that pitch is at least partly determined by temporal mechanisms.     

Preparation of calibrating standards for x‐ray fluorescence spectrometry of trace metals in plastics

Convenient x‐ray fluorescent spectrometry was developed for the determination of V, Cr, Co, Ni, Ge and Sb in plastic materials. The calibrating standards were prepared by casting of polyurethane or polyester including a xylene solution of organometallic compounds as a standard. The calibrating disk had a homogeneous elemental distribution and excellent durability. The calibration curves of six elements showed a good linearity of less than 50 mass ppm for V and Ni, 100 mass ppm for Co and Ge, 200 mass ppm for Cr, and 400 mass ppm for Sb. The lower limits of detection (3σ) of the present method were 0.19 mass ppm for V, 0.42 for Cr, 0.24 for Co, 0.18 for Ni, 0.066 for Ge, and 2.1 for Sb. The proposed method has been applied to several different industrial plastics. The quantitative results are in good agreement with those obtained by the AAS method and x‐ray fluorescent spectrometry using the fundamental parameter calculation method. Copyright © 2003 John Wiley & Sons, Ltd.     

蛛丝和蚕丝化学元素X射线荧光光谱分析及其应用

采用X射线荧光光谱(XRF)方法研究蛛丝和蚕丝的化学元素组成,探讨成丝机制中金属离子的作用及生物丝性能优良的元素基础。XRF分析蚕丝中C含量是47.10%、O为29.92%、N是16.52%;金属元素包括：Ca含量0.166 2%、Mg含量0.104 0%和K含量0.039 5%,而Na,Zn,Ni,Fe和Cr是微量元素。Ca和Mg元素含量高,在桑蚕吐丝机制中起着重要的作用。在蛛丝中,主要的非金属元素是：C含量44.09%、O含量26.64%和N含量22.34%。高含量的N元素可能是蛛丝优异的刚性和韧性性能的元素基础。在蛛丝中,Na含量0.268 0%、K含量0.081 4%和Mg含量0.011 6%,而Ca,Zn,Fe,Cu和Cr则是微量元素。蛛丝中Na和K元素含量高,在蜘蛛吐丝机制中可能起重要作用。运用数学统计方法研究生物丝元素组成与XRF元素分析结果吻合。     

Structural and Thermodynamic Peculiarities of Core-Shell Particles at Fluid Interfaces from Triangular Lattice Models

A triangular lattice model for pattern formation by core-shell particles at fluid interfaces is introduced and studied for the particle to core diameter ratio equal to 3. Repulsion for overlapping shells and attraction at larger distances due to capillary forces are assumed. Ground states and thermodynamic properties are determined analytically and by Monte Carlo simulations for soft outer- and stiffer inner shells, with different decay rates of the interparticle repulsion. We find that thermodynamic properties are qualitatively the same for slow and for fast decay of the repulsive potential, but the ordered phases are stable for temperature ranges, depending strongly on the shape of the repulsive potential. More importantly, there are two types of patterns formed for fixed chemical potential—one for a slow and another one for a fast decay of the repulsion at small distances. In the first case, two different patterns—for example clusters or stripes—occur with the same probability for some range of the chemical potential. For a fixed concentration, an interface is formed between two ordered phases with the closest concentration, and the surface tension takes the same value for all stable interfaces. In the case of degeneracy, a stable interface cannot be formed for one out of four combinations of the coexisting phases, because of a larger surface tension. Our results show that by tuning the architecture of a thick polymeric shell, many different patterns can be obtained for a sufficiently low temperature.     

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.     

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.     

气相质谱法对小鼠体内甲苯二异氰酸酯代谢产物的鉴定分析

应用气相质谱测定小鼠体内甲苯二异氰酸酯(TDI)的代谢产物,并鉴别了其在机体中的代谢途径。TDI色谱条件为Supelco PTETM-5色谱柱(30 mm×0.25 mm×0.25 μm),起始柱温90 ℃保持30 min,以40 ℃·min-1升至280 ℃,保持5.25 min;汽化室温度250 ℃;载气为氦气,流速为1.0μL·min-1。TDI体内代谢产物色谱条件为30+2mX0.25+0.02mm 94%甲基、4%乙烯基键合相弹性石英毛细柱,起始温度30 ℃保持5 min,以8 ℃·min-1升至280 ℃,保持5 min。汽化室温度250 ℃;载气为氦气,流速1.0μL·min-1。质谱条件为电离方式EI,电离能量70eV,连接管温度280 ℃,扫描范围35～350μ;进样量1.0μL。结果表明2,4甲苯二异氰酸酯在血液、尿液、粪便中都被代谢成为2,4甲苯二胺。GC-MS法可有效分离并鉴定TDI体内代谢产物。     

Ground State and Single Vortex for Bose-Einstein Condensates in Anisotropic Traps

For Bose-Einstein condensation of neutral atoms in anisotropic traps at zero temperature, we present simple analytical methods for computing the properties of ground state and single vortex of Bose-Einstein condensates, and compare those results to extensive numerical simulations. The critical angular velocity for production of vortices is calculated for both positive and negative scattering lengths a, and find an analytical expression for the large-N limit of the vortex critical angular velocity for a 〉0, and the critical number for condensate population approaches the point of collapse for a 〈 0, by using approximate variational method.     

Long jump rates in surface diffusion: W on W(110)

We have reexamined the diffusion of W adatoms on W(110) using the field ion microscope. The diffusivity is in good agreement with previous results and reveals no unusual features, but from observations of the distribution of displacements, corrected for diffusion during temperature transients, we have for the first time been able to measure the temperature dependence of rates for nearest-neighbor and double jumps, as well as for vertical and horizontal transitions. Activation energies and frequency factors for all the long jumps are significantly larger than for single jumps, and a simple model is proposed to account for our observations.     

Lattice dynamics of FCC transition metals: A pseudopotential approach

Simple pseudopotential model for the binding energy of transition metals is proposed. The contribution of thes-like electrons is calculated in the second-order perturbation theory for the local model pseudopotential while that of thed-like electrons is taken into account by introduction of repulsive short-range interatomic potential. Model parameters were determined for ten fcc transitions metals (Cu, Ni, Fe, Co, Ag, Pd, Rh, Au, Pt, and Ir). This model was used for the calculation of the phonon dispersion and the density of states, as well as for the elastic constants and their pressure derivatives. Good agreement with experimental data was achieved for the overall shape of phonon spectra and even for the position of the Kohn anomalies in Pd and Pt. Existence of such anomalies is also stated for predicted phonon spectra of rhodium and iridium.     

Design of wavelength-selective waveplates using genetic algorithm

Wavelength-selective waveplates, which act either identically or differently for plural wavelengths, are useful for optical systems that handle plural wavelengths. However, they cannot be analytically designed because of the complexity of their structure. Genetic algorithm is one of the methods for solving optimization problems and is used for several kinds of optical design (e.g., design of thin films, diffractive optical elements, and lenses). I considered that it is effective for designing wavelength-selective waveplates also and tried to design them using the genetic algorithm for the first time to the best of my knowledge. As a result, four types of wavelength-selective waveplate for three wavelengths (405, 650, and 780 nm) were successfully designed. These waveplates are useful for Blu-ray Disc/Digital Versatile Disc/Compact Disc compatible optical pickups.     

Total cross sections for ve and ve interactions and search for neutrino oscillations and decay

About 200 and 60 candidates for electron neutrino and antineutrino interactions, respectively, have been analyzed in the heavy liquid bubble chamber Gargamelle exposed to the CERN PS neutrino beam. Evidence for scaling has been found for these interactions, with slopes of the cross sections in good agreement with those obtained for muon neutrino and antineutrino events in the same chamber. No evidence appears for oscillations of neutrinos or antineutrinos, which would induce in the present experiment an excess of electron or positron events. The corresponding limits are given as functions of the mixing parameter, for the finite mass Majorana neutrinos. The possibility of a multiplicative law for the lepton number has also been investigated. A search for isolated electron-positron pairs revealed no excess in the forward direction, in contradiction to the expectation for muonic neutrino and antineutrino decays. The corresponding limits on the c.m. half lifetimes are given.     

Speckle reduction methods in laser-based picture projectors

Laser sources have been promised for many years to be better light sources as compared to traditional lamps or light-emitting diodes (LEDs) for projectors, which enable projectors having wide colour gamut for vivid image, super brightness and high contrast for the best picture quality, long lifetime for maintain free operation, mercury free, and low power consumption for green environment. A major technology obstacle in using lasers for projection has been the speckle noise caused by to the coherent nature of the lasers. For speckle reduction, current state of the art solutions apply moving parts with large physical space demand. Solutions beyond the state of the art need to be developed such as integrated optical components, hybrid MOEMS devices, and active phase modulators for compact speckle reduction. In this article, major methods reported in the literature for the speckle reduction in laser projectors are presented and explained. With the advancement in semiconductor lasers with largely reduced cost for the red, green and the blue primary colours, and the developed methods for their speckle reduction, it is hoped that the lasers will be widely utilized in different projector applications in the near future.     

Electrons in a strong magnetic field on a disk

The problem of interacting electrons moving under the influence of a strong magnetic field in two dimensions on a finite disk is reconsidered. First, the results of exact diagonalizations for up to N = 9 electrons for Coulomb as well as for a short-range interaction are used in the search for a peculiar ground state corresponding to filling factor 1/3. Not for the Coulomb, but only for the short-range interaction, can the 1/3-state be safely identified amongst the spectra of various filling factors close to 1/3. Second, the propositions of the concept of quasiparticles, as used in the hierarchical theory, are examined in view of the exact results for the disk geometry. Whereas the theory for the quasiholes is in complete accordance with the spectra, for the quasielectrons, finite size corrections make an analysis difficult. For the quasielectron energy, an extrapolation to N→ ∞ is given and compared with the corresponding extrapolations of three different proposals for trial wave functions. While the limiting value for the best trial wave function is very close to the limit of the exact results, the behavior of the finite size corrections of the exact energies and of the trial wave functions, respectively, is qualitatively rather different.     

Some aspects of the holstein problem

The following are considered: the principles involved in selecting a system of trial functions for the variational method of solving the Holstein problem; a method for determining the eigenfunctions for the cylindrical problem; the Voigt distribution of intensity along the profile of a nonreabsorbed line; and a method for finding eigenvalues for a layer of moderate optical thickness.The authors wish to thank A. S. Popov, L. A. Smirnova, and V. G. Blinkova for aid in the computations, and Professor Krause (Windsor University, Canada) for useful discussions.     

Mechanisms underlying the detection of frequency modulation

Frequency modulation detection limens (FMDLs) were measured for carrier frequencies (f(c)) of 1000, 4000, and 6000 Hz, using modulation frequencies (f(m)) of 2 and 10 Hz and levels of 20 and 60 dB sensation level (SL), both with and without random amplitude modulation (AM), applied in all intervals of a forced-choice trial. The AM was intended to disrupt excitation-pattern cues. At 60 dB SL, the deleterious effect of the AM was smaller for f(m) = 2 than for f(m) = 10 Hz for f(c) = 1000 and 4000 Hz, respectively, while for f(c) = 6000 Hz the deleterious effect was large and similar for the two values of f(m). This is consistent with the idea that, for f(c) below about 5000 Hz and f(m) = 2 Hz, frequency modulation can be detected via changes in phase locking over time. However, at 20 dB SL, the deleterious effect of the added AM for f(c) = 1000 and 4000 Hz was similar for the two values of f(m), while for f(c) = 6000 Hz, the deleterious effect of the AM was greater for f(m) = 10 than for f(m) = 2 Hz. It is suggested that, at low SLs, the auditory filters become relatively sharp and phase locking weakens, so that excitation-pattern cues influence FMDLs even for low f(c) and low f(m).