Three Dimensional Modeling of Shaft with Process Structures on CATIA

Three dimensional models of shaft were completed on CATIA Part Design module with the Chinese national standard （GB） process structures such as chamfers, threads and tool withdrawal grooves, center holes, flat/woodruff/gib head taper keyseats, grinding undercuts, straight-sidedsplines, circlip slots and collars. The modeling steps are arranged in dialog menu interface by VB 6.0, the shaft creator, that permits users input geometric feature based parameters explicitly, and the standardized processdata are reorganized in Excel files that can be invoked correspondingly in the modeling procedure. It is aimed that this process may supply a simple way for shaft rapid modeling and comprehensive discipline for engineering students in their professional design activities.     

LTE小区搜索中一种新的SSS检测算法

主要研究了SSS检测, 提出一种新的SSS检测算法。该算法首先利用滑动平均窗修正接收的PSS处估计出的信道频率响应, 并用修正后的信道频率响应对接收的SSS序列进行信道补偿; 其次, 算法对信道补偿后的序列进行实数提取操作, 消除虚部数据干扰; 最后算法联合两个连续的SSS接收序列进行检测进一步提高检测性能。TDD和FFD两种模式下的仿真结果表明：该算法可以较好地实现SSS检测且比现有几种SSS检测算法在低信噪比（SNR<0 dB）条件下具有更好的检测性能。     

Oxygen enrichment from air through multilayer thin low‐density polyethylene films

Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm². They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm². The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331     

Continuous Oxygen Ion Transfer Medium as a Catalyst for High Selective Oxidative Dehydrogenation of Ethane

An oxygen permeable mixed ion and electron conducting membrane (OPMIECM) was used as an oxygen transfer medium as well as a catalyst for the oxidative dehydrogenation of ethane to produce ethylene. O^2- species transported through the membrane reacted with ethane to produce ethylene before it recombined to gaseous O², so that the deep oxidation of the products was greatly suppressed. As a result, 80% selectivity of ethylene at 84% ethane conversion was achieved, whereas 53.7% ethylene selectivity was obtained using a conventional fixed-bed reactor under the same reaction conditions with the same catalyst at 800 °C. A 100 h continuous operation of this process was carried out and the result indicates the feasibility for practical applications.     

丙烯酸酯聚氨酯/SiO2纳米复合涂层结构与形态对其耐刮伤性影响研究

以四乙氧基硅烷(TEOS)作为主要前驱体,通过改变溶胶-凝胶工艺参数制得了结构和形态各异的丙烯酸酯聚氨酯/SiO2纳米复合涂层,利用TEM、SAXS等手段表征涂层的结构与形态,由洗刷前后涂层的失光率来表征耐刮伤性,详细探讨了纳米复合涂层耐刮伤性与SiO2相特征、有机无机相作用力及SiO2质量分数之间的关系。研究表明:丙烯酸酯聚氨酯涂层中引入纳米SiO2相后,耐刮伤性明显提高。有机相与SiO2相之间的作用力是影响涂层耐刮伤性的最重要因素,作用力越强,耐刮伤性越好。网络状纳米SiO2与颗粒状纳米SiO2相比,更有利于耐刮伤性的提高,且网络状纳米SiO2质量分数越大,耐刮伤性越佳,但SiO2相的致密度和尺寸对耐刮伤性影响较小。对于颗粒状胶体SiO2,在15~160 nm范围内,粒径对耐刮伤性没有明显影响;随着胶体SiO2粒子的质量分数增加,耐刮伤性先增大后减小。     

AIN陶瓷烧结技术研究进展

氮化铝（AIN）因其具有高热导率，作为基片材料在电子元器件中得到日益重视。本文主要论述了氮化铝陶瓷制备过程中各种烧结参数，包括烧结助剂、烧结气氛、保温时间、常压烧结、热压烧结、微波烧结和等离子烧结等对氮化铝陶瓷性能的影响。并指出可通过合适的AIN粉体制备技术，结合快速烧结方法可得到具有晶粒细小、结构均匀、高致密度和高导热率的AIN陶瓷。     

Injectable hydrogels of poly(?-caprolactone-co-glycolide)-poly(ethylene glycol)-poly(?-caprolactone-co-glycolide) triblock copolymer aqueous solutions

Thermogelling triblock copolymers of poly(?-caprolactone-co-glycolide)-poly(ethylene glycol)-poly(?-caprolactone-co-glycolide) [P(CL-GA)-PEG-P(CL-GA)] were successfully prepared by control of the hydrophilicity/hydrophobicity balance and chemical compositions of the copolymers. The aqueous solutions of the copolymers underwent sol-gel transition as the temperature was increased from 20 to 60 °C. The amphiphilic copolymer formed micelles in water and a gel was formed by aggregation of micelles. The structure parameters played a critical role in determining sol-gel transition behavior. Either increasing [GA]/[CL] ratio or decreasing P(CL-GA) block length could induce the increase of the lower sol-gel transition temperature. Glycolide (GA) was incorporated into the polymer chain to increase the polymer degradation rate. Sustained release of rifampicin for approximately 32 days was obtained from the gel. It is believed to have potential applications in drug delivery and tissue engineering.     

Lamellar Morphology of Poly(3-hydroxybutyrate)/Poly(ethylene oxide) Blends as Studied via Small Angle X-ray Scattering

The lamellar morphology of a melt-miscible blend consisting of two crystalline constituents, poly(3-hydroxybutyrate) (PHB) and poly(ethylene oxide) (PEO) have been investigated by means of small angle X-ray scattering (SAXS). The blend was a crystalline/amorphous system when temperatures lay between the melting point of PEO (ca. T _m ^PEO=60C) and that of PHB (ca. T _m ^PHB=170C), while it became a crystalline/crystalline system below T _m ^PEO. The crystalline microstructures of the blends were induced by two types of crystallization history, i.e. one-step and two-step crystallizations. In the one-step crystallization, the blends were directly quenched from the melt to room temperature to allow simultaneous PHB and PEO crystallization. The two-step crystallization involved first cooling to 70C to allow PHB crystallization for 72 h followed by cooling to room temperature (ca. 19C) to allow PEO crystallization. In the crystalline/crystalline state, two scattering peaks have been observed in the Lorentz-corrected SAXS profiles, irrespective of the crystallization histories, meaning that crystallization created separate PHB and PEO lamellar stack domains. One-step crystallization yielded lamellar stack domains containing almost pure PHB and PEO lamellae. Two-step crystallization generated almost pure PHB lamellar domains and the PEO lamellar domains with inserted PHB lamellae. In the crystalline/amorphous state, the composition dependence of the amorphous layer thickness (l _a), the presence of zero-angle scattering, and the volume fraction of the PHB lamellar stack (_s) revealed that both one-step and two-step crystallizations, generated the interfibrillar segregation morphology, where the extent of interfibrillar segregation of amorphous PEO increased with increasing PEO content.     

杀菌剂环唑醇的合成研究

分别以氯苯、环丙基乙酸和氯丙烯、对氯苯甲醛为起始原料合成4-氯苯基环丙基甲基酮,再经甲基化反应、硫叶立德反应生成环氧化合物,最后与1,2,4-三唑反应合成环唑醇,含量大于95%,总收率为34.2%(以环丙基乙酸计)。