An Integrative Theory of Urban Design

The ideas that inform urban design usually coalesce around contending approaches, each associated with one or two leading writers. This article finds that these approaches share an intellectual foundation: They implicitly acknowledge the “noncommodifiability” of the human experience across property boundaries. They share the view that good design seeks to reintegrate the human experience of urban form in the face of real estate markets that would treat land and buildings as discrete commodities. The great writers on urban design have more or less explicitly defended this intellectual position by appeal to the nebulous concept of the “organic.” Rather than just asserting that everything is part of an organic whole, this article identifies the integrative principles through which urban environments can transcend commodification. These principles include good form, legibility, vitality, and meaning.     

基于UG/WAVE的柴油机缸盖参数化设计

本文根据企业近年来对缸盖、气缸体等复杂零部件快速设计的需求,以缸盖为例介绍了这类复杂零部件快速设计的一般要求和方法。然后利用UG/WAVE技术对某柴油机缸盖进行了自顶向下的参数化设计,缩短了缸盖的改型和研发周期,提高了产品的市场竞争力。     

基于VMT的DDR-SDRAM控制器功能验证

介绍了一种基于验证模型技术(VMT)的DDR-SDRAM控制器的功能验证方案。该方案完成了DDR-SDRAM控制器对DDR-SDRAM模型的读写以及AHB 2.0协议的兼容性验证。VMT的使用加快了验证平台的搭建和验证用例的编写。通过分析自动校对结果、仿真波形和覆盖率报告,实现控制器功能验证的快速收敛。FPGA原型验证进一步证明了该方案的可行性。     

The elasticity of demand for gasoline in China

This paper estimates the price and income elasticities of demand for gasoline in China. Our estimates of the intermediate-run price elasticity of gasoline demand range between −0.497 and −0.196, and our estimates of the intermediate-run income elasticity of gasoline demand range between 1.01 and 1.05. We also extend previous studies to estimate the vehicle miles traveled (VMT) elasticity and obtain a range from −0.882 to −0.579.     

VMT/P(AMPS-co-AA)复合高吸水树脂的性能测试

研究了溶液pH、盐浓度对辉光放电电解等离子体引发合成的蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸) (VMT/P(AMPS-co-AA)) 复合高吸水树脂的溶胀行为的影响,考察了染料pH、吸附时间、染料浓度等因素对复合高吸水树脂吸附量的影响,同时对树脂的吸附-解吸性能进行了研究。结果表明, VMT/P(AMPS-co-AA)具有高吸水性、pH敏感性、盐敏感性以及高吸附性。该树脂在蒸馏水中的最大溶胀率达到822.4 g/g,对阳离子染料亚甲基蓝(MB)、结晶紫(CV)和孔雀石绿(MG)的吸附量分别可达2027.8, 2171.8和883.2 mg/g。在pH=6.5和25℃下,其对染料的吸附行为符合动力学准二级模型,该树脂还具有一定的吸附-解吸性能和重复利用性能。     

VMT在USBD模块验证中的应用

在集成电路设计中,功能验证是主要的瓶颈之一.据估计,验证工作占设计工作开销的60%以上.Synopsys公司VMT(Vera验证模型技术)工具可减小验证的工作量、节约时间.文中描述了使用VMT对USBD(通用串行总线器件)模块的验证,验证了USBD部件符合协议规范、完成系统定义的要求,并对不同的数据传输方式进行比较.本设计已通过MPW(multi-project wafer)流片生产出实际芯片,其效果在实际的芯片上得到了验证,达到了设计的效果.     

插层型蔗糖/蛭石纳米复合材料的制备

以蔗糖和蛭石为原料,在超声辅助条件下采用溶液插层法制备插层型蔗糖/蛭石纳米复合材料。X射线衍射（XRD）、红外光谱（FTIR）分析表明,蔗糖/蛭石复合物样品的d001值为1.852nm;样品的红外谱图中出现甲基和亚甲基特征峰2761cm-1和2969cm-1。将蔗糖/蛭石复合物在氮气氛下碳化后,样品的XRD（d001=1.247nm）和红外光谱结果（甲基和亚甲基特征峰2761cm-1和2969cm-1消失）表明,碳/蛭石复合材料层间夹有碳,进一步证实得到插层型蔗糖/蛭石复合材料。同时,确定了优化插层反应工艺条件,超声功率为400W,物料配比为蛭石：蔗糖=1：2.5,超声水化时间为0.5h,超声反应温度为70℃,反应时间为2.5h,静置时间2h。     

A parametric analysis of future ethanol use in the light-duty transportation sector: Can the US meet its Renewable Fuel Standard goals without an enforcement mechanism?

The modified Renewable Fuel Standard (RFS2) prescribes a volume of biofuels to be used in the United States transportation sector each year through 2022. As the dominant component of the transportation sector, we consider the feasibility of the light-duty vehicle (LDV) parc to provide enough demand for biofuels to satisfy RFS2. Sensitivity studies show that the fuel price differential between gasoline and ethanol blendstocks, such as E85, is the principal factor in LDV biofuel consumption. The numbers of flex fuel vehicles and biofuel refueling stations will grow given a favorable price differential. However, unless the feedstock price differential becomes extreme (biomass prices below $100 per dry ton and oil prices above $215 per barrel), which deviates from historical price trends, LDV parc biofuel consumption will fall short of the RFS2 mandate without an enforcement mechanism. Additionally, such commodity prices might increase biofuel consumption in the short-term, but discourage use of biofuels in the long-term as other technologies that do not rely on any gasoline blendstock may be preferable. Finally, the RFS2 program goals of reducing fossil fuel consumption and transportation greenhouse gas emissions could be achieved through other pathways, such as notable improvements in conventional vehicle efficiency.     

Preparation and Properties of Polypropylene/Vermiculite Nanocomposite Through Solid-State Shear Compounding (S3C) Method Using Pan-Mill Equipment

Nanocomposites of polypropylene (PP) and vermiculite (VMT) were successfully prepared by solid-state shear compounding (S³C) using pan-mill equipment without any compatibilizer. The structure and morphology of nanocomposites were determined by X-ray diffraction and scanning and transmission electron microscopy techniques, the crystallization behavior of composites was determined by differential scanning calorimetry; the thermal and mechanical properties of composites are also presented in the paper. The results show that the VMT sheets were partly exfoliated in solid state and the intercalated and exfoliated VMT was formed in the PP matrix by compounding PP and PP/VMT copowders, indicating that S³C is a novel method to prepare polymer/vermiculite nanocomposites.     

辉光放电电解等离子体法制备VMT/P(AMPS-co-AA)高吸水树脂

在水溶液中,以蛭石(VMT)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和丙烯酸(AA)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,用辉光放电电解等离子体(GDEP)引发制备蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸)(VMT/P(AMPS-co-AA))复合高吸水树脂。考察了放电电压、放电时间、蛭石用量和交联剂含量对复合高吸水树脂吸水溶胀性能的影响,用FT-IR、XRD、TG、SEM对复合高吸水树脂的结构、形貌和热稳定性进行了表征,同时探讨了可能的引发聚合机理。结果表明, VMT 表面的羟基与AMPS和AA中的C=C键发生接枝共聚形成了无机/有机无定形共聚物,该材料表面呈现粗糙、多孔的三维网状结构,热稳定性良好,GDEP引发是一个自由基引发的链增长过程。