A successive estimation scheme of an occupation probability†

This paper treats of an estimation problem of an occupation probability of some targets in a Tegion M by an infra-red detector followed by a threshold device in a satellite.

First, a successive estimation scheme is proposed for an estimation problem of an occurrence probability of signal 1 of the 1,0 type binary signal sequence disturbed by some noise. The estimate obtained by this scheme is shown to converge to the true value with probability one and in the mean square. Then, as an application of this scheme for the occurrence probability, an estimation scheme for an occupation probability is proposed. Two examples illustrating the scheme for an occupation probability are presented.     

基于组合优化策略在毕赤酵母中高效表达杜邦嗜热菌脂肪酶北大核心CSCD

杜邦嗜热菌脂肪酶(LIP1)是一种在洗涤行业、生物柴油制备、油脂改性等领域具有良好应用潜力的碱性脂肪酶,然而其天然产量极低,难以满足产业化需求。采用组合优化策略筛选出高效表达LIP1的毕赤酵母重组菌株。首先,构建毕赤酵母密码子偏好性优化的LIP1基因,通过高浓度G418抗性平板和BMMY-罗丹明B定性平板筛选出脂肪酶活性较高的重组菌株;其次,利用信号肽优化和分子伴侣共表达优化筛选得到一株高效表达的重组毕赤酵母菌株GS115/pPIC9K-Mss-SSA4-LIP1,采用碱滴定法测定其酶活,采用比色法测定其底物特异性。结果表明,经组合优化策略筛选出的菌株在摇瓶和5 L发酵罐中发酵最高分泌酶活分别达到1 136 U/mL和12 150 U/mL。底物特异性结果显示重组脂肪酶LIP1最适底物为C8链长的对硝基苯酚酯。综上所述,基于组合优化策略实现了LIP1在毕赤酵母中的高效表达,为未来LIP1的产业化奠定基础。     

Characterization of Common Squid Using Several Freshness Indicators

Changes in several components and properties were examined to find appropriate indicators of freshness of common squid during storage at 0°C, 5°C and 10°C. Total viable counts of bacteria, pH and volatile basic nitrogen did not change significantly during 2 wk storage at 0°C. Unlike usual fish meat, K value in squid muscle changed very quickly, but Hx/AMP ratio was a better indicator. Agmatine increased before initial decomposition started but was not suitable as an early freshness indicator. Free basic amino acids, arginine and ornithine also changed rapidly. Basic amino acids such as arginine and ornithine appeared to be appropriate indicators of freshness of common squid.     

用低碱度硫铝酸盐水泥制备的砂浆和混凝土的物理性能(英文)

制备了低碱度硫铝酸盐水泥,并对由该水泥制备的砂浆和混凝土的物理性能进行了测试分析。结果表明:低碱度硫铝酸盐水泥砂浆和混凝土的抗压强度发展良好,过量的缓凝剂会降低其早期强度。在水灰比为0.65的情况下,其砂浆和混凝土的长期抗压强度发展缓慢。水灰比和抗压强度之间不存在线性关系。新拌混凝土会出现体积收缩,但随之转变为体积膨胀,并持续10～30d。当粉煤灰和石灰石粉作为掺合料替代部分水泥时,其砂浆和混凝土的强度会下降,但仍能满足实际应用的要求;此外,粉煤灰和石灰石替代部分水泥还能减小混凝土的绝热温升、改善其流动性。     

Performance of Dead‐Time Compensation Methods in Three‐Phase Grid‐Connection Converters

This paper discusses the performance of compensation methods for dead‐time voltage error in voltage‐source grid‐connection pulse‐width modulation converters. The theoretical analysis in this paper reveals the relationship between the voltage error and the current ripples through the converter. The analytical results imply that the voltage error is strongly affected by the amplitude of the current ripples as well as the source power factor. This paper proposes a new compensation method which makes it possible to use two lookup tables to reduce the calculation time in the controller. The compensation characteristics are compared by using a 200‐V 5‐kW three‐phase grid‐connection converter. As a result, conventional approximation‐based compensation methods exhibit an acceptable performance in a restricted power‐factor operation range. In contrast, the turn‐off transition‐based compensation method and the proposed method have a good compensation performance all over the power factor.     

钨含量对12％Cr耐热钢力学性能的影响SCIEI

本文报道了钨的含量对12％Cr-W-V-Nb耐热钢高温及室温力学性能的影响。试验结果表明:当钨的含量在2.2—3.0wt-％之间变化时,室温抗拉性能没有明显变化,但冲击韧性却随着钨量的增加而下降。另一方面,钨量的增加提高了短时间的持久强度,但对长时间的持久强度却没有改善作用。钨量的增加对析出行为有两方面的作用:促进Fe_2W型Laves相的形成并增加析出相总量;加速了回火后在高温加热过程中析出相的粗化。钨对高温力学性能的影响与析出特性有密切关系。在持久寿命较短时,析出相来不及粗化,析出量的增加造成了析出强化效果的加强,即钨量的增加提高了高温强度;而当长时间加热后,析出相发生了明显的粗化,降低了析出强化效果。     

玻璃炭球的二步活化法——一种高活化收率的途径

以玻璃炭球为原料,采用在干燥空气流中500℃高温热处理3h(第一步活化处理),而后在415℃低温处理不同时间(第二步活化处理)的两步活化法制取了一系列活性炭球。依据77KN2吸/脱附等温线,应用BET、αs-plot和BJH法测定了所得活性炭球的孔结构。结果表明:第一步活化处理后,在炭球表面生成少量大孔(中孔甚至大孔),这些大孔是第二步活化时活化气体(空气)的扩散入口,使得第二步活化处理时微孔的生成量增加。由此可以认为这种二步活化法是获得高收率的较高比面积和微孔容积活性炭的一种有效途径。