基于遗传算法的最大开启电流估计

集成电路设计进入深亚微米阶段后，静态功耗成为低功耗设计中的一个瓶颈．电源门控法可以同时有效地降低动态功耗和静态功耗，是一项具有广阔应用前景的技术．电源门控电路的最大电流是由最大开启电流和最大的正常运行电流决定，它是电路设计的一个十分重要的参数，如何对它进行快速准确的估计已经成为一个新的问题．另外，冒险功耗是电路整体功耗中非常重要的组成部分，该文通过研究发现，在电路开启阶段同样存在冒险，同时消耗了大量的能量．文章考虑了组合电路的冒险现象，提出了一种基于遗传算法的最大开启电流的估计方法，对ISCAS85电路的实验结果表明，电源门控电路的开启最大功耗可能比正常情况下的最大功耗还要大．该文的方法具有较小的复杂性，可以仅用随机模拟的2．77％的时间，获得12．90％的最大开启电流值增量。     

瞬态波形记录仪中计数器的CPLD实现

本文介绍了采用CPLD实现瞬态波形记录仪计数器的三种方法由74系列的芯片构成原理图;由LPM库元件设计;采用VHDL(超高速集成电路硬件描述语言)进行计数器的设计.文中给出了前两种方法设计的计数器及仿真图形.经实际检验采用CPLD实现的计数器具有功能强大,易修改,抗干扰性强等优点.     

双端口RAM在动态应变仪中的应用

本文介绍了双端口存储器;分析了双端口RAM在动态应变仪中的应用.通过双端口的使用解决了数据采集的连续问题,实现了数据采集的低速与计算机的快速之间很好的匹配.     

高冲击加速度虚拟测试技术研究

为了降低弹体对硬目标深层侵彻的试验成本,结合"虚拟测试"(Virtual Test)在现代科技和工程技术领域的应用,提出了高冲击加速度虚拟测试技术的概念,从正面和反面两个角度分析了高冲击加速度虚拟测试系统的组成,使试验在实际进行前可以通过该系统预测试验结果和可能出现的问题,从而大幅度缩短产品的研制周期和研制经费.     

Simultaneous structure and elastic wave velocity measurement of SiO2 glass at high pressures and high temperatures in a Paris-Edinburgh cell

An integration of multi-angle energy-dispersive x-ray diffraction and ultrasonic elastic wave velocity measurements in a Paris-Edinburgh cell enabled us to simultaneously investigate the structures and elastic wave velocities of amorphous materials at high pressure and high temperature conditions. We report the first simultaneous structure and elastic wave velocity measurement for SiO(2) glass at pressures up to 6.8 GPa at around 500°C. The first sharp diffraction peak (FSDP) in the structure factor S(Q) evidently shifted to higher Q with increasing pressure, reflecting the shrinking of intermediate-range order, while the Si-O bond distance was almost unchanged up to 6.8 GPa. In correlation with the shift of FSDP position, compressional wave velocity (Vp) and Poisson's ratio increased markedly with increasing pressure. In contrast, shear wave velocity (Vs) changed only at pressures below 4 GPa, and then remained unchanged at ~4.0-6.8 GPa. These observations indicate a strong correlation between the intermediate range order variations and Vp or Poisson's ratio, but a complicated behavior for Vs. The result demonstrates a new capability of simultaneous measurement of structures and elastic wave velocities at high pressure and high temperature conditions to provide direct link between microscopic structure and macroscopic elastic properties of amorphous materials.     

Oversample Reconstruction Based on a Strong Inter-Diagonal Matrix for an Optical Microscanning Thermal Microscope Imaging System

Based on a strong inter-diagonal matrix and Taylor series expansions,an oversample reconstruction method was proposed to calibrate the optical micro-scanning error.The technique can obtain regular 2 × 2 microscanning undersampling images from the real irregular undersampling images,and can then obtain a high spatial oversample resolution image.Simulations and experiments show that the proposed technique can reduce optical micro-scanning error and improve the system's spatial resolution.The algorithm is simple,fast and has low computational complexity.It can also be applied to other electro-optical imaging systems to improve their spatial resolution and has a widespread application prospect.     

Stability of fiber trajectories for winding toroidal pressure vessels

In this paper the fiber trajectory stability of filament wound toroidal pressure vessels is evaluated for two most frequently used patterns: single helical winding, helical and hoop winding. The basic equations of equilibrium for fibers on a torus are given based on netting analysis. The governing equations that determine helical winding angles along the meridional direction are derived for the two winding patterns. The slippage coefficients of the obtained fiber trajectories are calculated using the non-geodesic law and differential geometry. The condition between the hoop-to-helical thickness ratio and the relative bend radius of the toroid is also formulated to prevent fiber bridging on the concave surface. The fiber slippage and bridging tendencies are outlined and compared, corresponding to various relative bend radii and hoop-to-helical thickness ratios. The results show that the single helical winding process provides better stability of fiber trajectories, in terms of both fiber slippage and bridging, than the helical and hoop winding. The toroidal vessel with larger relative bend radius requires lower coefficient of friction between the fiber bundle and the supporting surface. The present analysis for fiber trajectory stability affords a useful reference tool for designing filament-wound toroidal pressure vessels.     

Preparation and Characterization of Taxifolin Form II by Antisolvent Recrystallization

To improve the aqueous solubility and dissolution rate of taxifolin, taxifolin form II was successfully prepared through antisolvent recrystallization, in which 1‐butyl‐3‐methylimidazolium tetrafluoroborate and dichloromethane were used as solvent and antisolvent, respectively. The properties of taxifolin form II were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, solid‐state NMR spectroscopy, the dissolving capability test, and the bioavailability test. The chemical structure of taxifolin form II was not changed, but its morphology and crystalline structure changed during the recrystallization process. Moreover, taxifolin form II showed higher solubility, faster dissolution rate, and better bioavailability than taxifolin form I.     

Facile synthesis route to monodispersed platelet-like SBA-15 silica

We here report a facile synthesis route to monodispersed platelet-like SBA-15 mesoporous silica employing kinetically controlled micelles as templates. In previous preparations of SBA-15 silica, it was believed that thermodynamically equilibrated micelles were used as templates. The kinetically controlled micelle has never been used before to generate periodic mesoporous materials with unique morphology. Monodispersed hexagonal platelet-like SBA-15 microparticles were prepared via a very facile synthesis route by tuning the micelle formation process, i.e. the stirring rate and the time of dissolution of the triblock copolymer and formation of the micelles. Shorter micelle formation time and faster stirring are essential to generate platelet-like SBA-15 silica particles. It is expected to apply in the synthesis of a wide variety of mesophase materials.     

Effect of superfine grinding on physicochemical and antioxidant properties of pomegranate peel

Pomegranate peel powders were prepared by superfine grinding, whose effects were investigated on the composition, functional and antioxidant properties of the pomegranate peel products. Fluidised bed jet milling technology was used to process superfine pomegranate peel powder. The physical–chemical properties of coarse powder A (D50 = 413.4 μm) and B (D50 = 197.1 μm), fine powder C (D50 = 142.6 μm) and D (D50 = 41.2 μm), superfine powder E (D50 = 7.68 μm) and raw material powder (RMP) (D50 = 352.2 μm) were investigated in this study. SEM images revealed the shape and surface morphology of six pomegranate peel powders. The physical determinations showed that the smaller the powder particle size was, the greater the surface area (from 0.214 to 1.597 m² g^?1) and bulk density (from 0.653 to 0.751 g mL^?1) were, the smaller the angles of repose (from 51.69° to 38.74°) and slide (from 48.32° to 34.18°) were. The water holding capacity (WHC), water‐solubility index (WSI), polyphenols and flavonoids release were significantly improved as the size of pomegranate peel particle decreased. The results of FTIR and UV indicated that grinding process would not influence chemical composition of pomegranate peel. Vitamin C (VC) and butylated hydroxytoluene (BHT) were used in DPPH scavenging activity determination, and DPPH scavenging activity was A < RMP < BHT < B < C < D < E < VC.