Improving the coefficient of performance of thermoelectric cooling systems: a review

This paper reviews research carried out to improve the coefficient of performance of thermoelectric cooling systems during the past decade. This includes development of new materials for thermoelectric modules, optimisation of module design and fabrication, system analysis and heat exchange efficiency. Several conclusions are drawn. Copyright © 2004 John Wiley & Sons, Ltd.     

基于CMS91航空FHS系统的设计与实现

综述了目前国内民用航空机场在飞机加油生产过程中采用手工操作方式的缺陷；介绍了国际航空市场的航空加油管理系统中的新技术。在此基础上，结合深圳宝安机场承远航空油料公司的实际生产要求，借鉴国际航油管理新技术提出了基于CMS91模块的无线通信模式实现机场油料管理；设计并研制了基于GPRS CMS91模块的FHS雏型系统，经测试能够满足生产需求，具有一定的推广应用价值。     

Maximum useful energy-rate analysis of an endoreversible Joule–Brayton cogeneration cycle

Endoreversible Joule–Brayton cogeneration cycle has been optimized based on a new criterion, total useful energy-rate (including power output and useful heat output), and the efficiency at maximum total useful energy rate has also been determined. The effects of various cycle parameters on the maximum dimensionless total useful-energy rate and the efficiency at maximum total useful-energy rate have been assessed. Variations of dimensionless total useful-energy rate with respect to efficiency have also been analyzed. The reversible Joule–Brayton power cycle is a special case of the analyzed cycle.     

大鼠呼吸道上皮细胞~3H-TdR标记指数

本文利用~3H-TdR 掺入技术研究大鼠呼吸道上皮细胞的标记类型和数量。大鼠腹腔注射7.4×10~4Bq/g(体重)~3H-TdR6小时后,制片计数气管和支气管上皮标记及非标记的基底细胞和粘液细胞,计算出标记指数。结果表明,气管及支气管基底细胞标记指数分别为0.0052和0.0198,粘液细胞标记指数分别为0.0014和0.0047,说明两类细胞都是具有分裂能力的癌形成相关细胞。     

黑曲霉产纤维素酶菌种的激光选育

报道了以黑曲霉为出发菌株．采用铜蒸气激光诱变处理．筛选纤维素酶高产菌株．获得了４株高产的突变菌株，用稻草麸皮固体培养基，２８℃发酵培养４天．每克湿曲的最高酶活：ＣＭＣ酶活（Ｃｘ）为２８３９ｍｇ葡萄糖／ｇ·ｈ、滤纸酶活（ＣＬ）为２９９ｍｇ葡萄糖／ｇ·ｈ，β－葡萄糖苷酶活为１０９１ｍｇ葡萄糖／ｇ·ｈ。并且对突变株Ｎｏ．８号菌株的菌落形态、生长发育及发酵周期等变异性状、纤维素酶高产性状的稳定性等方面都进行了深入的测试和分析对比．从试验结果表明．激光诱变技术方便实用．效果明显．是一种新的微生物诱变育种的理想方法之一。     

Optimal training for block transmissions over doubly selective wireless fading channels

High data rates give rise to frequency-selective propagation, whereas carrier frequency-offsets and mobility-induced Doppler shifts introduce time-selectivity in wireless links. To mitigate the resulting time- and frequency-selective (or doubly selective) channels, optimal training sequences have been designed only for special cases: pilot symbol assisted modulation (PSAM) for time-selective channels and pilot tone-assisted orthogonal frequency division multiplexing (OFDM) for frequency-selective channels. Relying on a basis expansion channel model, we design low-complexity optimal PSAM for block transmissions over doubly selective channels. The optimality in designing our PSAM parameters consists of maximizing a tight lower bound on the average channel capacity that is shown to be equivalent to the minimization of the minimum mean-square channel estimation error. Numerical results corroborate our theoretical designs.     

The effects of disjunct sampling and averaging time on maximum mean wind speeds

Conventionally, the 50-year wind is calculated on basis of the annual maxima of consecutive 10-min averages. Very often, however, the averages are saved with a temporal spacing of several hours. We call it disjunct sampling. It may also happen that the wind speeds are averaged over a longer time period before being saved. In either case, the extreme wind will be underestimated. This paper investigates the effects of the disjunct sampling interval and the averaging time on the attenuation of the extreme wind estimation by means of a simple theoretical approach as well as measurements. The measurements include climates dominated by extratropical lows, as well as more complicated, wind climate types. For both, the investigations are done for omni-directional and sector-wise situations. The theory assumes the time series is a Gaussian Markov chain and it performs adequately for sites in the extratropical regions. The sector-wise situation is more complicated. The attenuation of the extreme mean winds for a sector shows a dependency on the frequency of occurrence from that sector.     

高密度聚乙烯在砂浆中磨蚀的研究

自制了一台有６只臂的旋臂式磨蚀仪，旋臂上的样条座可使样条只在指定的有效磨蚀面积上发生磨蚀。磨蚀试验相对误差约为３０％。实验结果在明，高密度聚乙烯５０００Ｓ、６０９８的磨蚀无差别，仅为Ａ３钢的１／８。这３种样品皆在３０～４５°冲击角度时有最大磨蚀。     

自由基一步法生产聚异丁烯丁二酸酐及其丁二酰亚胺无灰分散剂

聚异丁烯丁二酸酐（烯酐）是生产丁二酰亚胺型，丁二酸酯型和酚醛胺型无灰分散剂的重要中间体。针对当前热加合工艺和氯化工艺生产燃酐的缺陷，开发了自由基一步法烃化工艺合成烯酐。该工艺经过小试，工业放大试验，生产的烯酐和丁二酰亚胺产品质量符合现行技术指标要求，丁二酰亚胺产品经外光谱分析，其结构与国内外类剂T－152，OLOA－373和LZ－6418相近。新工艺与现行的氯化工艺相比具有工艺简单易行，生产装置投资少，反应温度低，生产周期短，能耗低，生产成本低的特点，而且从工艺源头根除了氯气污染源，符合国家生态安要求。     

高功率CO2激光薄膜的离子辅助镀工艺进展

真空蒸发镀膜技术已经应用了很多年，随着激光技术的发展，人们对激光薄膜尤其是高功率激光薄膜的质量要求越来越高，离子辅助沉积薄膜技术已被广泛用来作为一种改善光学薄膜特性的工艺手段。本文简单地介绍了这项技术的原理及国内外研究现状；总结了该技术的优、缺点；客观评价了该技术的应用前景；对该技术今后的研究方向提出了建议。