基于FPGA的曼彻斯特编码DSG的设计与实现

利用可编程门阵列(FPGA)技术的可重构性与灵活性,设计实现了一种数据率可调、具有曼彻斯特编码功能的数字信号发生器。该信号发生器结合了数字信号发生器和曼彻斯特编码的优点,弥补了信号发生器不具备曼彻斯特编码功能的不足。该系统采用硬件描述语言VHDL进行设计,使用Quartus II 8.0进行综合布线,最终适配到DE2开发板并用示波器等设备进行了验证测试。整个设计硬件结构简单、占用逻辑器件资源少、可靠性高、灵活性强、适应性好,具有一定的理论价值和应用前景。     

Pt-SnO2/C电催化剂异型直接乙醇燃料电池的性能

以掺杂石墨粉的中间相碳微球(MCMB/G)烧结管为阴极支撑体,采用浸涂工艺分别制备了扩散层和催化层,通过在其外表面包裹Nafion 117膜制得管状异型阴极并组装成异型直接乙醇燃料电池,采用水热乙二醇制备了适用于直接乙醇燃料电池的阳极电催化剂,并通过XRD,TEM和EDS等技术对其进行了表征.采用线性循环伏安曲线、交流阻抗等测试手段,对Pt-SnO2/C电催化剂异型直接乙醇燃料电池进行了性能测试,并考察了温度、氧气流量等对电池极化性能的影响.结果表明:异型电池阻抗大于传统的平板电池,但其活化后电池阻抗明显下降;较高的氧气流量和较高的工作温度有利于提高电池性能;60℃条件下,Pt-SnO2/C电催化剂异型直接乙醇燃料电池功率密度达到8.5 mW·cm-2.     

真空联合堆载预压处理深厚软基试验和数值分析

为提高深厚软基的深层加固效果,对某高速公路软基采用真空联合堆载预压法处理,改进了竖向排水通道形式.在试验路段中分别设置150 mm宽的塑料排水板和插入100 mm袋装砂井作为新型竖向排水体,其中细管长度10 m,直径8 mm,对比验证了两种新型竖向排水体在提高深厚软弱土层排水固结的功效.结果表明:150 mm宽塑料排水板内真空度衰减较少,预压期地基沉降量大,8 mm细管可增大袋装砂井中真空压力的传递深度.在修正剑桥模型的基础上,考虑了软土的流变性以及卸载后再加载的变形特性,改进土体本构模型,提出了相应的真空预压有限元数值计算方法.实例验算表明:计算值与实测值的数据大小及其变化规律都吻合较好.     

周礼全先生的学术思想及其贡献——纪念周先生90周年诞辰

主要论述了周礼全先生的学术思想和贡献。周先生在哲学研究领域做出了重要的贡献,并大力宣传哲学家的使命;周先生大力传播现代逻辑,提倡现代逻辑应该理论联系实际;周先生具有学术创新精神,是中国自然语言逻辑的开拓者和传播者;周先生对中国逻辑史的研究和发展做出了重要贡献;周先生客观公正,提倡学术民主,敢于坚持真理,倡导学术批评。周先生最重要的成果就是由他亲自执笔、主编,于1994年出版的《逻辑——正确思维和成功交际的理论》,这部力作无论在国内还是国际上都具有开创性意义,提出了一个包括意义、语境、隐涵和预设等为主体骨干的语言逻辑体系,描述了一种成功交际的理论和一个语言交际图式。     

Precipitation and stability of reversed austenite in 9Ni steel

A new method was used to analyze the factors affecting the precipitation of reversed austenite during tempering. The samples were kept at various tempering temperatures for 10 min and their length changes were recorded. Then, the precipitation of reversed austenite which led to the length reduction was shown by thermal expansion curves. The results show that the effects of process parameters on the precipitation of reversed austenite can be determined more accurately by this method than by X-ray diffraction. When the quenching and tempering process is adopted, both the lower quenching temperature and higher tempering temperature can promote the precipitation of reversed austenite during tempering; and when the quenching, lamellarizing, and tempering process is used, intercritical quenching is considered beneficial to the precipitation of reversed austenite in the subsequent tempering because of Ni segregation during holding at the intercritical temperature.     

Room temperature plastic deformation behavior of ZrCuNiAl bulk metallic glasses

The Zr_62.55Cu_17.55Ni_9.9Al₁₀ bulk metallic glass (BMG) was prepared by using copper-mold suction-casting. X-ray diffraction and differential scanning calorimetry were utilized to determine its structure and thermal stability. Uniaxial compression and Rockwell indentation tests were adopted to study the plastic deformation behavior at room temperature. The results show that the glass transition temperature and the onset temperature of exothermic reaction of the BMG are 651.5 and 748 K, respectively. During the compression test, the BMGs undergo an engineering strain of about 2.5%, i.e., true strain of 2.8%, and then fracture. The BMGs deform via the formation and propagation of shear bands. Under indentation loading, the BMGs deform through the formation of radiation-like and circular shear bands. The circular shear bands form earlier than the radiation-like ones. The formation mechanism of shear bands in the BMGs was analyzed and discussed.     

Thermodynamic analysis on the formation mechanism of MgO·Al<Subscript>2</Subscript>O<Subscript>3</Subscript> spinel type inclusions in casing steel

MgO·Al₂O₃ spinel type inclusions in casing steel were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that there are three forms. One is pure MgO·Al₂O₃ spinel, another is the composite oxide of the Mg-Al-Ca-Si-O system, and the third is the complex with oxide as a core covered by sulfide. The formation mechanisms were studied. The influences of slag basicity and vacuum degree on the magnesium content during the vacuum treatment of molten steel and furnace lining in molten steel were calculated with the coexistence theory of slag structure. The results show that the magnesium content increases with the increase in slag basicity and aluminum content in molten steel, and decreases with the increase in CO partial pressure.     

煤粉壁摩擦特性的实验与模拟

为了研究仓壁材料性质、粒径对煤粉运动壁摩擦角的影响,用Jenike剪切测试仪,测试不同粒径煤试样在不锈钢板、碳钢板、环氧板3种常用仓壁材料上的运动壁摩擦力.结合Jenike松散物料流动理论,探讨了不同粒径煤试样运动壁摩擦系数的变化.结果表明:仓壁材料表面的粗糙度越大,煤粉的运动壁摩擦系数越大;材料刚度越大,煤粉的运动壁摩擦系数也越大;水分一定时,煤试样中小粒径煤粉含量越多,壁摩擦系数越大.同时,用离散单元法(DEM)对这一壁摩擦过程进行模拟研究.分析比较模拟结果和实验结果表明:数值模型能够有效模拟实验过程,仓壁材料粗糙度、刚度以及煤粉粒径对壁摩擦系数的影响规律与实验结果相同.     

有机磷水解酶全细胞生物催化剂的特性

利用有机磷水解酶大肠杆菌细胞表面展示工程菌为全细胞催化剂,研究了其降解对氧磷的反应.确定了最适反应条件为:反应温度37 ℃、pH值8.0、底物浓度2.0 mmol/L、振荡速率120 r/min,在此条件下反应5 h,对氧磷降解率可达80%左右,且全细胞催化剂具有较好的稳定性和可重复使用性,显示了良好的应用前景.     

High-resolution carbon isotope record for the Paleocene-Eocene thermal maximum from the Nanyang Basin,Central China

The Paleocene-Eocene thermal maximum (PETM) was a transient episode of global warming, associated with massive atmospheric greenhouse gas input that occurred at the Paleocene/Eocene boundary. Biostratigraphic and isotope stratigraphic studies indicate that the PETM event is well documented in the marl deposits of the Yuhuangding section in the Nanyang Basin, Central China, with a carbon isotope negative excursion of ~6.1‰ within 19-m-thick marl deposits. This is the highest resolution record of the PETM so far found in the world. The PETM event was triggered within 2-cm-thick marl sediments, with a decrease of δ¹³C (stable carbon isotope ratio) from –3.2‰ to –5.2‰, suggesting a massive methane hydrate release for a transient period that was possibly caused by a catastrophic event. A comparison between marine and terrestrial records indicates a “Three-Phase Model” for the PETM event. Initially there is a rapid negative excursion in the δ¹³C record, followed by a slowly decreasing trend, and then a gradual positive recovery, corresponding respectively to a rapid dissociation of oceanic methane hydrate, followed by a slow release of methane and then the consumption of the released methane.