Chinese kangs and building energy consumption

Chinese kangs are an integrated system for cooking, sleeping and heating in rural Northern China with more than 2000 years history. In 2004 there were 67 million Chinese kangs used by 44 million rural families or 174 million people. Chinese kangs store surplus heat from stove during cooking and releases it later for both home heating and localized bed heating. Such a widely used heating system has been rarely studied. Understanding kangs is important for developing new effective home heating systems for better energy efficiency and improving indoor air quality in Northern China. In this paper, we review and present some preliminary results from our field measurement and mathematical modeling, and discuss the development of Chinese kangs as related to future energy consumption in rural homes, and building energy consumption in China in general. We suggest that transition and new technologies for rural home heating in Northern China, i.e. the future of Chinese kangs, should be considered as the top priority in managing future building energy consumption in China. Supported by the grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. HKU 7154/05E) and National Natural Science Foundation of China 2007 Young Researcher Award (Grant No. 50729803) The work is also a part of the International Energy Agency Annex 44 project on Integrating Environmentally Responsive Elements in Buildings.     

蒸汽发生器几种水位控制方法的对比与分析

在所建立的U型管蒸汽发生器动态数学模型基础上，研究和分析了蒸汽发生器水位的动态特性．根据这些特性设计了蒸汽发生器串级PID水位控制、前馈—反馈水位控制、Smith水位预估补偿控制3种控制系统，并进行了控制系统仿真研究，结果显示3种控制系统都有较好的控制能力，有各自的特点．研究结果对于U型管蒸汽发生器的水位控制系统设计具有一定的指导意义．     

一种基于小波的数字调制信号识别算法

小波包变换理论上可以实现信号频带的均匀划分,从而更好地提取信号的时频特征.作者首先介绍了卷积型小波包算法,然后分析了三种主要的数字调制信号的小波变换特征,提出了一种基于小波的数字调制信号识别算法,仿真结果表明该算法能够识别典型的数字调制信号,而且具有较好的抗噪声性能.     

冻干法制备乳酸菌发酵剂工艺条件研究

对乳酸菌冻干发酵剂的制备工艺进行了初步探索，通过对乳酸菌液体摇瓶培养中的参数和超滤浓缩特性参数测定，确定了发酵剂冻干制备的工艺参数．由于乳酸菌冻干发酵剂有着广泛应用，因此，本工艺在实际上有一定的参考价值。     

温度对石墨烯条带拉伸力学性能影响的模拟研究

利用分子动力学模拟,分析了单层石墨烯条带在热力学温度[1K,800K]范围内拉伸力学性能对条带手性,宽度及模拟温度的依赖性.结果表明,相同条件下锯齿型石墨烯条带较扶手椅型石墨烯条带具有更大的弹性模量及拉伸强度;条带宽度的增加对弹性模量有较小影响,但拉伸强度随宽度的增加有明显变化;石墨烯条带拉伸强度随温度的升高而减小,均匀变温模拟条件下拉伸强度较室温恒温模拟结果有所变化,且温度变化率是影响拉伸强度的因之一.     

北美红豆杉的引种繁殖和叶片中紫杉醇的积累

北美红豆杉（Ｔａｘｕｓ ｍｅｄｉａ）树叶中紫杉醇的含量高于云南红豆杉树皮中的含量,５年生的北美红豆杉即可采叶提取紫极醇。在重庆引种繁殖３年生物北美红豆杉取得成功,扦插繁殖成活率达９０％以上,品种Ｄａｒｋ Ｇｒｅｅｎ Ｓｐｒｅａｄｅｒ叶片中紫杉醇含量高达０．０５１％,是值得三峡库区海拨１０００ｍ的退耕还林地区栽培的优良经济林木。     

Simulation of the continuous casting process in a mold of free-cutting steel 38MnVS based on a MiLE method

A new method called mixed Lagrangian and Eulerian (MiLE) method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS. The simulation results are basically in agreement with experimental data in the literature, achieving the three-dimensional visualization of temperature distribution, melt flow, shell thickness, and stress distribution of blooms in a mold. It is shown that the flow velocity of steel melt becomes smaller gradually as the casting proceeds. When the flow reaches a certain depth, two types of flow patterns can be observed in the upper zone of the mold. The first flow pattern is to flow downwards, and the second one is to flow upwards to the meniscus. The corner temperature is higher, and the thickness is thinner than those in the mid-face. The effective stress in the corner area is much bigger than that in the mid-face, indicating that the corner area is the dangerous zone of cracking.     

混合计算智能学习算法在系统辨识中的应用

提出既具有较快的收敛性,又具有良好的全局收敛特性的混合计算智能学习算法,并将其应用于系统辨识。仿真结果表明,此方法是有效可行的。     

尾矿酸化及其对尾矿砂抗剪强度的影响研究

为揭示尾矿酸化本质及其对尾矿砂抗剪强度的影响,开展了动态浸渍试验.从湖南省某铅锌矿采取了尾矿砂试样,采取加入双氧水的方式促使尾矿砂中的硫化物(主要为黄铁矿)发生氧化产酸.在浸泡试验的基础上开展了MLA(矿物解离分析仪)矿物成分分析、颗粒分析、抗剪强度等一系列实验.试验结果表明:尾矿矿物成分中随着黄铁矿氧化程度的增加,黄铁矿含量减少、碱性物质(方解石、白云母)减少、砂粒(粗粒)含量减少、粉粒(细粒)含量增加、粘聚力C增大、摩察角φ减小、尾矿砂土抗剪强度降低.     

The Optimal Solution of the Model with Physical and Human Capital Adjustment Costs

We prove that the model with physical and human capital adjustment costs has optimal solution when the production function is increasing return and the structure of vetor fields of the model changes substantially when the prodution function from decreasing return turns to increasing return. And it is shown that the economy is improved when the coefficients of adjustment costs become small.