MERIS observations of chlorophyll-a dynamics in Erhai Lake between 2003 and 2009

The Medium Resolution Imaging Spectrometer (MERIS) was used to investigate the spatial and temporal dynamics of chlorophyll-a (chl-a) in Erhai Lake, the second largest freshwater lake in the Yunnan province of China. Six chl-a retrieval models, including four Basic ERS & Envisat (A)ATSR and Meris Toolbox (BEAM) software-incorporated algorithms and MERIS three-band and two-band models, were validated to find the best fit to extract chl-a concentration in Erhai Lake. With a chl-a range of 5–15 mg m^–3, the Lakes/Eutrophic method showed the best performance. The algorithm was then applied to eight-year cloud-free MERIS images between 2003 and 2009, with seasonal and inter-annual variability analysed. Long-term chl-a distributions of Erhai Lake revealed significant seasonal and inter-annual variability. The mean chl-a of the south lake was higher in summer (14.3 mg m^–3) than in spring (10.1 mg m^–3), while generally lower chl-a was found in the north lake with a mean chl-a of 6.4 mg m^–3 in spring and 9.0 mg m^–3 in summer, respectively. An increasing trend was found between 2006 and 2009, and the increasing rate was 12.9% for annual chl-a of the entire lake. While chl-a seasonality was attributed to the seasonal changes of the local temperature, the inter-annual variation was possibly linked to the discharged wastewater from Dali City. This work could provide critical information for decision-makers to manage Erhai Lake’s aquatic ecosystems.     

Modeling of rate-dependent phase transition in bacterial flagellar filament

Recent experiment of Darnton and Berg [34] showed that phase transition of bacterial flagellar filament is loading rate-dependent. The object of this paper is to describe the observed loading rate-dependent phase transition responses of the filament by using time dependent Ginzberg–Landau continuum model. We developed a finite element method (FEM) code to simulate the phase transition under a displacement-controlled loading condition (controlled helix-twist) by using viscosity-type kinetics. Our FEM simulation captures the main features of the rate-dependence: under slow loading (i.e., loading time ? the relaxation time) the filament phase transition is an equilibrium process and each phase grows via interface propagation on the Maxwell line; under rapid loading (i.e., loading time ? the relaxation time), the phase transition does not occur and the response is elastic. Our FEM model provides a tool to study the effects of loading-rate dependent phase transition for bio-filament with viscous kinetics.     

PBS-co-DEG与热塑性淀粉共混膜的性能研究

采用流延法制备了不同二甘醇(DEG)含量的聚丁二酸丁二醇二甘醇共聚酯(PBS-co-DEG)与热塑性淀粉(TPS)共混的复合膜,通过核磁共振氢谱仪、傅里叶变换红外光谱仪、凝胶渗透色谱仪、热重分析仪、紫外–可见分光光度计、偏光显微镜等对共聚酯的结构及复合膜的性能进行了表征和测试,采用N435脂肪酶对复合膜进行了降解实验。结果表明,随DEG含量的增加PBS-co-DEG/TPS复合膜的亲水性、光透过率和断裂伸长率均有所增加,热稳定性变化不明显;与PBS/TPS复合膜相比,PBS-co-DEG/TPS复合膜的酶降解速率显著提高。     

Ground source heat pump system: A review of simulation in China

With attractive advantages of high efficiency, energy saving and environmental friendliness, the ground source heat pump (GSHP) system has been used widely in China in recent years. This paper summarizes the analytical solution, numerical solution and experimental investigation of the heat transfer of the ground heat exchanger (GHE), analyzes the simulation model and long-term operation performance of the GSHP system, and introduces the lastest hybrid ground source heat pump (HGSHP) system. In addition, this paper discusses and summarizes the shortages and imperfects of the current research on the simulation of the GSHP system and gives some recommendations for future work.     

红外焦平面探测器中间层杨氏模量提取研究

为系统研究热冲击下InSb焦平面探测器的形变规律,需借助多层材料形变分析方程组求得其形变解析解。本文在分析、模拟双组份弹性材料均匀混合后其等效杨氏模量随体积分数变化趋势的基础上,借助有限元软件ANSYS对InSb焦平面探测器中间层等效杨氏模量的提取进行系统研究。分析结果表明,直接采用线弹性材料模型模拟的结果与真实材料的等效杨氏模量相去甚远,需用黏塑性模型方能给出符合实际的中间层等效杨氏模量;在InSb焦平面探测器典型结构设计中,中间层的等效杨氏模量随体积分数的演化规律可用线性方程描述,这为后续探测器结构优化提供了理论分析模型支撑。     

多信道中短波广播接收机的开发简介

随着数字技术的不断发展,在各个领域数字技术逐步取代模拟技术.当前数字化广播接收机伴随A/D技术和数字处理技术的高速发展,其性能已经接近传统模拟接收机,未来势必取代传统模拟接收机.本文介绍的一种多路中短波广播接收机的设计方法,由于采用在全波段数字化处理技术,将模拟射频信号直接数字化,通过FPGA模块,完成多信道广播的处理,较传统模拟广播接收机,在抗干扰、数据采集、集成性和性价比上存在巨大的优势,并成功验证了实现方案.     

南宁市防洪排涝工程当务之急的初探

防洪排涝是按照人们的要求,用工程手段去改变洪水的天然特性。本文从南宁市气候情况入手,分析了南宁市防洪排涝工程存在问题及解决措施。充分印证了,防洪排涝工程已成为南宁市城市建设的当务之急。     

A regional construction R&D evaluation system for China

Expenditure on R&D in China’s construction industry has been relatively low in comparison with many developed countries for a number of years—a situation considered to be a major barrier to the industry’s competitiveness in general and unsatisfactory as regards industry development of the 31 regions involved. A major problem with this is the lack of a sufficiently sophisticated method of objectively evaluating R&D activity in what are quite complex circumstances considering the size and regional differences that exist in this part of the world. A regional construction R&D evaluation system (RCRES) is presented, aimed at rectifying the situation. This is based on 12 indicators drawn from the Chinese Government’s R&D Inventory of Resources in consultation with a small group of experts in the field, and further factor analysed into three groups. From this, the required evaluation is obtained by a simple formula. Examination of the results provides a ranking list of the R&D performance of each of the 31 regions, indicating a general disproportion between coastal and inland regions and highlighting regions receiving special emphasis or currently lacking in development. The understanding on this is vital for the future of China’s construction industry.     

利用磁测方法确定水下磁性目标体的深度

水下磁性目标物的线度一般远小于探测距离,其产生的场可以近似为磁偶极子产生的场,本文研究适用于估算磁偶极子深度的特征点法和切线法,给出了近似计算公式,并且编制了可视化应用软件。利用这两种方法对某海域的磁测资料进行了反演计算,结果表明：这两种方法确定水下磁性目标体的深度能够取得较好效果。