一种采用单双跳变的低功耗确定性BIST方案

为实现低功耗和高故障覆盖率,基于单跳变测试技术和2-bit扭环计数器,提出一种新型的单双跳变的确定性测试向量产生器.首先,与一般的确定性测试方案直接存储确定性种子不同,利用ROM存储控制信号并通过单双跳变生成确定性种子和确定性测试向量,这样控制信号的长度约为确定性种子的1/2,有利于降低功耗并节约存储空间.其次,2-bit减法计数器合理地过滤了冗余向量,大大缩短了测试时间并降低总体能耗.最后,为了适应不同的测试需求,还设计了相应的测试向量压缩算法和三种x指定算法.实验结果表明,平均功耗分别降低了42.36%、32.32%、38.94%,测试长度分别减少了77.6%、86.1%、84.3%,测试数据分别压缩了79.4%、65.2%、68.1%.     

Systematic study of optoelectronic and transport properties of cesium lead halide (Cs2PbX6; X=Cl,Br, I) double perovskites for solar cell applications

A systematic density functional theory investigation of Cs₂PbX₆ (X = Cl, Br, I) double perovskites is presented. The lattice constants are computed after structure optimization and using Birch-Murnaghan equations, which agree to the experimental literature. The mechanical stability conditions satisfy Born criteria, and the ductile nature is evidenced by the calculated Poisson's (v) and Pugh's ratios (B₀/G) because all three double perovskites exhibit values higher than the respective critical values v = 0.26 and B₀/G = 1.75. A detailed study of the optoelectronic properties reveals these double perovskites as promising candidates for future optical devices due to their direct band gaps (within 0.45–2.54 eV) and large absorption coefficients 5.95 × 10⁵ cm⁻¹, which are suitable for solar cell applications. ZT calculations demonstrate minute variations within 200–800 K and computed parameter values are quite favorable for thermoelectric applications of these materials in the future. A p-type semiconducting nature is predicted by the computed thermoelectric properties. Additionally, computed refractive indices show Cs₂PbBr₆ and Cs₂PbI₆ exhibiting super-luminescent properties in the UV range. Therefore, the studied double perovskites provide further interest for future energy conversion and photonic based technologies.     

Structure-design strategy of 0–3 type (Bi0.32Sr0.42Na0.20)TiO3/MgO composite to boost energy storage density,efficiency and charge-discharge performance

A novel 0–3 type (Bi_0.32Sr_0.42Na_0.20)TiO₃/MgO composite is investigated in this work, which possesses a high stored energy storage density w_s˜2.50 J/cm³, recoverable energy storage density W_R˜2.09 J/cm³ with high efficiency η˜84% under low electric field (20 kV/mm). The excellent performance is owning to the increase of breakdown strength (BDS) value and the intrinsic mechanism for enhanced BDS value by MgO incorporation is disclosed by numerical simulations (COMSOL). Moreover, the studied composite exhibits excellent charge-discharge performance, the current density (C_D) and power density (P_D) are 1671 A/cm² and 150 MW/cm³, respectively, which are much superior to that of other ceramics. Besides, most of the stored energy is discharged within ˜0.15 μs via charge-discharge tests. This work not only provides a novel technique to designing bismuth-based ceramic capacitors with simultaneously high W_d, η and excellent charge-discharge performance, but also deepens the understandings of the role for the metallic oxide in the composite.     

Thermoluminescence parameters and kinetics of irradiated inorganic dust collected from black peppers

Irradiated foods can be detected by thermoluminescence (TL) of contaminating inorganic dust particles. In this study, black peppers were irradiated with gamma rays at doses of 1, 3, 5 and 10 kGy. The inorganic dust particles collected from irradiated black pepper are investigated. This study reports the mineral composition of this dust being, mainly quartz, feldspar and little amount clay minerals. The TL detection method is clearly able to distinguish irradiated and non-irradiated black peppers at the doses ranging from 1 to 10 kGy. The paper provides a detailed calculation of the activation energy (E), frequency factor (s) and the order of kinetics of the 240 °C TL identification peak in polymineral dust material. The experimental and computerized deconvolution results are consistent with the presence of a closely overlapping second-order TL peaks in the identification peak at 240 °C. The TL kinetic parameters of overlapping peaks were estimated by computerized deconvolution method. The computer deconvolution shows the existence of four well-defined TL peaks at 118, 210, 270 and 305 °C. These four peaks probably due to the combined TL of quartz and feldspar minerals.     

The effect of micro-grinding and micro-graphite flotation to upgrade the quality of calcite concentrate,with reference to Kurikka calcite marble deposit,Finland

High purity of calcium carbonate deposits are rare. Even the purest calcite marbles contain accessory minerals, which may degrade the deposit in terms of its suitability for paper pigment application. Most of these impurities could be removed by traditional calcite–silicate flotation to produce quality ground calcium carbonate. However, micro-graphite enclosed by calcite remains un-liberated with the traditional flotation particle size distribution. Further grinding alone simply exposes such graphite on the surface of calcite and reduces the brightness of the concentrate.In Kurikka calcite marble, micro-graphite particles of varying morphology occur along calcite grain boundaries and other crystallographic discontinuities. Due to such submicroscopic graphite particles, the calcite concentrate produced from the Kurikka calcite marble by calcite–silicate flotation gives an average ISO brightness value of 83.7.This study shows the application of micro-grinding followed by micro-graphite flotation to remove such fine-grained graphite. As a result, the quality of the calcite concentrate was upgraded to an average brightness value of 92.3.     

A lightweight low-current 10 K magnet for space-flight ADRs

Future space missions will include detectors and other components cooled to cryogenic temperatures by adiabatic demagnetization refrigerators (ADRs) coupled with mechanical cryocoolers. In such systems the ADRs require lightweight, low-current superconducting magnets. At least one of an ADR’s magnets must operate at the cryocooler’s coldest stage temperature. This temperature should be as high as possible in order to improve operating efficiency and design flexibility. Until now all space-flight compatible magnets have been made with NbTi wire, which has limited their operating temperatures to below about 5 K. We have developed a lightweight (1 Kg) low-current (8 A) Nb₃Sn magnet which produces a 3 T central field at 10 K. We explain the choice of this magnet’s specifications and describe its performance testing.     

Design method of the layered active magnetic regenerator (AMR) for hydrogen liquefaction by numerical simulation

The design procedure of an active magnetic regenerator (AMR) operating between liquid nitrogen temperature and liquid hydrogen temperature is discussed with the selected magnetic refrigerants. Selected magnetic refrigerants (GdNi₂, Dy_0.85Er_0.15Al₂, Dy_0.5Er_0.5Al₂, and Gd_0.1Dy_0.9Ni₂) that have different transition temperatures are layered in an AMR to widen the temperature span. The optimum volume fraction of the layered refrigerants for the maximum COP with minimum volume is designed in a two-stage active magnetic regenerative refrigerator (AMRR) using one dimensional numerical simulation. The entropy generation in each stage of the AMR is calculated by the numerical simulation to optimize the proposed design. The main sources of the entropy generation in the AMR are pressure drop, convection and conduction heat transfers in the AMR. However, the entropy generation by the convective heat transfer is mostly dominant in the optimized cases. In this paper, the design parameters and the operating conditions such as the distribution of the selected refrigerants in the layered AMR, the intermediate temperature between two stages and the mass flow rate of heat transfer fluid are specifically determined to maximize the performance of the AMR. The proposed design method will facilitate the construction of AMR systems with various magnetic refrigerants and conditions such as AMR size, operating temperature range, and magnetic field variation.     

Large-size-mismatch co-dopants for colossal permittivity rutile TiO2 ceramics with temperature stability

Colossal permittivity (CP) in donor-accepter co-doped rutile TiO₂ has attracted significant interest. Here, the CP behavior of (Ta?+?La) co-doped rutile TiO₂ ceramics were studied, where the ionic radii of Ta⁵⁺ and La³⁺ are much larger than that of Ti⁴⁺. The ceramics with an extremely low doping exhibit colossal dielectric permittivity (～2.6?×?10⁴) with an acceptable low dielectric loss (<0.07) in the frequency range from 40 to 10⁶?Hz. The CP properties obtained in (Ta?+?La) co-doped TiO₂ ceramics show excellent temperature stability over a wide temperature range of 20–400?°C. The X-ray diffraction analysis and the density functional theory calculation illustrates that the La₂³⁺${\text{V}}_{\text{o}}^{??}$Ti₂³⁺ and Ta₂⁵⁺Ti³⁺Ti⁴⁺ defect complexes with the lowest energy are responsible for the enhanced dielectric properties. Moreover, the defect complex formed by large-size trivalent substitutions and oxygen vacancy is very stable, and assists in improving temperature stability of the dielectric properties of co-doped rutile TiO₂ ceramics.     

Stochastic perturbation finite elements

This paper extends the stochastic perturbation method to vector-valued and matrix-valued functions. The numerical method for the response and reliability of uncertain structures is formulated using matrix calculus, Kronecker algebra and perturbation theory. Random variables and system derivatives are conveniently arranged into two-dimensional matrices and generalized mathematical formulae are obtained. The results derived are easily amenable to computational procedures.