Research of Application of Passive Natural Ventilated Strategies of High-Density Urban Area

High-density development is becoming an inevitable tendency in Chinese urbanization. In this study, the application of natural ventilation in high-density urban development is discussed. Based on the domestic and foreign study on natural ventilation, indoor and outdoor natural ventilated strategies, and the application on natural ventilation in underground space development are analyzed. From the study, the relationship between passive and active ventilated technologies is interpreted into what is described to be synergistic, complementary and additive.     

变频器在粉料干燥系统中的应用

以返料机、排料机和排烟机变频调速为例,介绍变频器在粉料干燥系统中的应用.突出了变频器在干燥系统中的自动控制.     

Solving IIR system identification by a variant of particle swarm optimization

A variant of particle swarm optimization (PSO) is represented to solve the infinitive impulse response (IIR) system identification problem. Called improved PSO (IPSO), it makes significant enhancement over PSO. To begin with, the population initialization step makes use of golden ratio to segment solution space so as to obtain high-quality solutions. It is followed by all particles using different inertia weights in velocity updating step, which is beneficial for preserving the balance between global search and local search. Subsequently, IPSO uses normal distribution to disturb the global best particle, which enhances its capacity of escaping from the local optimums. The above three operations cannot only guarantee high-quality solutions, strong global search capacity, and fast convergence rate, but also avoid low diversity, excessive local search, and premature stagnation. These properties of IPSO make it much better suited for IIR system identification problems. IPSO is applied on 12 examples. The experimental results amply demonstrate the capability of IPSO toward obtaining the best objective function values in all the cases. Compared with the other four PSO approaches, IPSO has stronger convergence and higher stability which clearly points out its desirable performance in search accuracy and identifying efficiency.

     

Production and radioprotective effects of pyrroloquinoline quinone

Pyrroloquinoline quinone (PQQ) was produced by fermentation of the Methylovorus sp. MP688 strain and purified by ion-exchange chromatography, crystallization and recrystallization. The yield of PQQ reached approximately 125 mg/L and highly pure PQQ was obtained. To determine the optimum dose of PQQ for radioprotection, three doses (2 mg/kg, 4 mg/kg, 8 mg/kg) of PQQ were orally administrated to the experimental animals subjected to a lethal dose of 8.0 Gy in survival test. Survival of mice in the irradiation + PQQ (4 mg/kg) group was found to be significantly higher in comparison with the irradiation and irradiation + nilestriol (10 mg/kg) groups. The numbers of hematocytes and bone marrow cells were measured for 21 days after sublethal 4 Gy gamma-ray irradiation with per os of 4 mg/kg of PQQ. The recovery of white blood cells, reticulocytes and bone marrow cells in the irradiation + PQQ group was faster than that in the irradiation group. Furthermore, the recovery of bone marrow cell in the irradiation + PQQ group was superior to that in irradiation + nilestriol group. Our results clearly indicate favourable effects on survival under higher lethal radiation doses and the ability of pyrroloquinoline quinine to enhance haemopoietic recovery after sublethal radiation exposure.     

CrPtMn顶钉扎自旋阀材料的交换耦合作用研究

反铁磁钉扎层和铁磁被钉扎层之间的交换耦合作用是高性能自旋阀材料研究中的一个关键因素。本工作研究了CrPtMn顶钉扎自旋阀材料中的交换耦合场(H_ex)与薄膜沉积条件以及退火处理之间的关系。研究表明: 沉积后的自旋阀材料中的H_ex大小与CrPtMn钉扎层的溅射工作气压关系不大, H_ex 约为7.96×10³ A/m。然而, 经过240℃退火2 h处理后, H_ex呈现出与CrPtMn沉积时的溅射工作气压相关的特性, 随着溅射工作气压的增加而增大。材料退火后的交换耦合场H_ex的温度特性良好, 室温下约为2.39×10⁴ A/m。Hex随着测试温度的升高而逐渐减小, 交换耦合场消失时的失效温度(blocking temperature)为315℃。