全流程低功耗设计技术的应用

随着便携式电子设备的日益使用,要求集成电路IC及SoC的功耗越来越低。在今后日益复杂的设计中,实现一个可靠的电源网络以减小功耗变成了主要的挑战。对于使用者来说,期待每一代新产品都具有新型功能,同时也希望产品的体积小并具有较长的工作时间。解决这个难题的方法之一就是采用新型的IC设计技术,以提供小而且高效的晶体管。在整个设计流程中,为了使器件的性能和可靠性最优,电源方面的限制非常关键。例如在逻辑门应用中,由于开关从一种状态转换到另一种状态从而引起动态功耗。在开关的转换过程中,和晶体管门极相连的所有内部电容将会被…     

Analysis of supersaturation and nucleation in a moving solution droplet with flowing supercritical carbon dioxide

A supercritical antisolvent (SAS) process is employed for production of solid nanoparticles from atomized droplets of dilute solution in a flowing supercritical carbon dioxide (SC CO₂) stream by attaining extremely high, very rapid, and uniform supersaturation. This is facilitated by a two‐way mass transfer of CO₂ and solvent, to and from the droplet respectively, rendering rapid reduction in equilibrium solubility of the solid solute in the ternary solution. The present work analyses the degree of supersaturation and nucleation kinetics in a single droplet of cholesterol solution in acetone during its flight in a flowing SC CO₂ stream. Both temperature and composition are assumed to be uniform within the droplet, and their variations with time are calculated by balancing the heat and mass transfer fluxes to and from the droplet. The equilibrium solubility of cholesterol with CO₂ dissolution has been predicted as being directly proportional to the Partial Molar Volume Fraction (PMVF) of acetone in the binary (CO₂–acetone) system. The degree of supersaturation has been simulated up to the time required to attain almost zero cholesterol solubility in the droplet for evaluating the rate of nucleation and the size of the stable critical nuclei formed. The effects of process parameters have been analysed in the pressure range of 7.1–35.0 MPa, temperature range of 313–333 K, SC CO₂ flow rate of 0.1136–1.136 mol s^?1, the ratio of the volumetric flow rates of CO₂‐to‐solution in the range of 100–1000, and the initial mole fraction of cholesterol in acetone solution in the range of 0.0025–0.010. The results confirm an extremely high and rapid increase in degree of supersaturation, very high nucleation rates and stable critical nucleus diameter of the order of a nanometre. Copyright © 2005 Society of Chemical Industry     

建立基于模型设计文化的最佳策略

本文引入了基于模型设计的概念,突出了其中的一些优点,详细讨论了组织中采用基于模型设计文化的10个最佳策略。这些最佳策略从不同工业领域的公司中收集,包括向基于模型设计的成功或者不成功的过渡。     

Determination of Binder Decomposition Kinetics for Specifying Heating Parameters in Binder Burnout Cycles

The decomposition kinetics of poly(vinyl butyral) binder from barium titanate multilayer ceramic capacitors with platinum metal electrodes were analyzed by thermogravimetric analysis as a function of the heating rate. The activation energy and pre-exponential factor for the decomposition kinetics were determined from two types of integral equations, from the Redhead method, and from the variation in heating rate method. The accuracy of the kinetic parameters determined from these methods was then evaluated for describing the observed rate of binder decomposition. Although the individual models yielded very different kinetic parameters, all were capable of describing the experimental data within ±15% accuracy. The kinetic parameters were then used in a coupled transport and kinetic model for describing the buildup of pressure within the ceramic green body as a function of the heating cycle. A methodology based on calculus of variations was also developed to predict the minimum duration for the binder burnout cycle.     

Urban water demand,climatic variation,and irrigation-water insecurity: interactive stressors and lessons for water governance from the Angat River basin (Philippines)

Climatic variation and intersectoral water competition increasingly challenge the effective provision of irrigation services. This article explores their combined effects on irrigation allocation from the Angat Reservoir (Philippines), where domestic water use in Metro Manila has overtaken regional irrigation as the dominant right-holder. Rules protecting Metro Manila’s large right to water ‘interact’ with dry spells to affect irrigation security in wet and dry seasons. Historically, irrigators were uncompensated because re-allocation’s cause was contested as (1) an unforeseeable climatic event (releasing domestic utilities of liability), or (2) produced by urban demand (requiring compensation). Trade-off rules must be prepared to navigate combinatory effects.     

Thermoplastic olefin/clay nanocomposites: Morphology and mechanical properties

Thermoplastic olefin (TPO)/clay nanocomposites were made with clay loadings of 0.6–6.7 wt %. The morphology of these TPO/clay nanocomposites was investigated with atomic force microscopy, transmission electron microscopy (TEM), and X‐ray diffraction. The ethylene–propylene rubber (EPR) particle morphology in the TPO underwent progressive particle breakup and decreased in particle size as the clay loading increased from 0.6 to 5.6 wt %. TEM micrographs showed that the clay platelets preferentially segregated to the rubber–particle interface. The breakup of the EPR particles was suspected to be due to the increasing melt viscosity observed as the clay loading increased or to the accompanying chemical modifiers of the clay, acting as interfacial agents and reducing the interfacial tension with a concomitant reduction in the particle size. The flexural modulus of the injection moldings increased monotonically as the clay loading increased. The unnotched (Izod) impact strength was substantially increased or maintained, whereas the notched (Izod) impact strength decreased modestly as the clay loading increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 928–936, 2004     

Simple Robust PID Tuning for Magnetic Levitation Systems Using Model-free Control and $${{\cal H}_\infty}$$ ℋ ∞ Control Strategies

International Journal of Control, Automation and Systems - This paper proposes two control techniques to provide robust tracking for magnetic levitation systems (MLS): model-free control (MFC) and...     

Games to induce specified equilibria

Media access protocols in wireless networks require each contending node to wait for a backoff time, chosen randomly from a fixed range, before attempting to transmit on a shared channel. However, nodes acting in their own selfish interest may not follow the protocol. In this paper, a static version of the problem is modeled as a strategic game played by non-cooperating, rational players (the nodes). The objective is to design a game which exhibits a unique, a priori mixed-strategy Nash equilibrium. In the context of the media access problem, the equilibrium of the game would correspond to nodes choosing backoff times randomly from a given range of values, according to the given distribution. We consider natural variations of the problems concerning the number of actions available to the players and show that it is possible to design such a game when there are at least two players that each have the largest number of possible actions among all players. In contrast, we show that if there are exactly two players with different number of actions available to them, then it becomes impossible to design a strategic game with a unique such Nash equilibrium.     

Biogenic copper nanoparticles promote the growth of pigeon pea (Cajanus cajan L.)

Environmental pollution and toxicity have been increasing due to the overuse of chemical fertilisers, which has encouraged nanotechnologists to develop eco‐friendly nano‐biofertilisers. The authors demonstrated the effect of biogenic copper nanoparticles (CuNPs) on the growth of pigeon pea (Cajanus cajan L.). The UV–visible analysis showed absorbance at 615 nm. Nanoparticle tracking and analysis revealed particle concentration of 2.18 × 10⁸ particles/ml, with an average size of 33 nm. Zeta potential was found to be −16.7 mV, which showed stability. X‐ray diffraction pattern depicted the face centred cubic structure of CuNPs; Fourier transform infrared spectroscopy demonstrated the capping due to acidic groups, and transmission electron micrograph showed nanoparticles with size 20–30 nm. The effect of CuNPs (20 ppm) on plant growth was studied, for the absorption of CuNPs by plants on photosynthesis, which was evaluated by measuring chlorophyll a fluorescence using Handy‐Plant Efficiency Analyser. CuNPs treatment showed a remarkable increase in height, root length, fresh and dry weights and performance index of seedlings. The overall growth of plants treated with CuNPs after 4 weeks was recorded. The results revealed that inoculation of CuNPs contribute growth and development of pigeon pea due to growth promoting activity of CuNPs.Inspec keywords: pollution, toxicology, nanotechnology, cropsOther keywords: biogenic copper nanoparticles, pigeon pea, Cajanus cajan L, environmental pollution, toxicity, chemical fertilisers, nanotechnologists, eco‐friendly nano‐biofertilisers, cash crop, UV‐visible analysis, nanoparticle tracking, zeta potential, X‐ray diffraction pattern, Fourier transform infrared spectroscopy, acidic groups, transmission electron micrograph, photosynthesis, chlorophyll, fluorescence, Handy‐Plant Efficiency Analyser, performance index