反照率影响建筑热环境的实验

针对城市建筑物外墙墙面反照率变化，建立两个建筑物理模型，在不同反照率墙面材料的条件下，对夏季建筑室内热环境进行了分析研究，验证了采用高反照率的墙面材料是一种有效的、主动的隔热节能方式；采用积分拟合方法对墙面材料的反照率进行了拟合，其结果为实际情况下城市建筑外墙墙面材料的选择及其隔热性能分析、反照率的计算及其对建筑热环境的影响评价提供了一条有效的途径。     

浅谈太阳热水器防冻措施

北方地区家用太阳热水器常出现这样的故障:冬天气温较低时,热水器回水管内的水冻成冰块,不能流动,造成热水器不能使用,给人们的生活带来不便。本文拟对这种故障的成因及防治措施作一简述。     

Low-OH MCVD fibres without a barrier layer using OH ? OD-exchanged substrate tubes

The effect of deuteration (OH ? OD exchange) of the MCVD substrate tube on the absorption loss in fibres was studied using tubes of moderate and low OH content. The OH absorption at 1.39 ?m was reduced from 4 dB/km and 0.9 dB/km to 1 dB/km and 0.7 dB/km, respectively, in fibres made without a barrier layer using deuterated tubes.     

А.М.ЛЯДУНОВ定理及其推广

证明(dy)/(dx)=ky+f(x),k为常数,f(x+ω)=f(x),有一个ω为周期的特解;然后推广以k为函数的情形最后推广到方程组。     

Simulation and Experimental Study on Thermal Conductivity of Nano-Granule Porous Material Based on Lattice-Boltzmann Method

Nano-porous materials have excellent thermal insulation performance,whose microstructure and physical properties,however,have great influence on the thermal conductivity.To accurately describe the stochastic phase distribution,a random internal morphology and structure generation-growth method,called the quartet structure generation set(QSGS),has been proposed in the present paper.The model was then imported into lattice Boltzmann algorithm as a fully resolved geometry and used to investigate the effects on heat transfer at the nanoscale.Furthermore,a three-dimensional Lattice Boltzmann method(LBM)D3Q15 was adopted to predict the nano-granule porous material effective thermal conductivity.This ideal method provided a significant advantage over similar porous media methods by directly controlling and adjusting of granule characteristics such as granule size,porosity and pore size distributions and studying their influence directly on thermal conductivity.To verify the accuracy of the proposed model,some experiments based on guarded hot plate meter(GHPM)were conducted.The results indicated that the simulation results agreed well with the experimental data and references values,which illustrated that this method was reliable to generate the microstructure of nano-granule.What’s more,the effects of pressure,core distribution probability,cd and density were investigated.There existed an optimal density(about 120 kg·m^-3)making the effective thermal conductivity being minimum and an optimal core distribution probability about cd=0.1 making the uniformity being the best.In addition,the present approach is applicable in dealing with other porous materials as well.     

住宅室内氡浓度的时间空间变化对肺癌危险度的影响

最近在甘肃进行的研究表明,居室内氡浓度的增加会导致肺癌危险度增高,这与以往进行的汇总分析和其他居室研究的综合分析结果一致(王作元,等．美国流行病学杂志,2002．155：554)。室内氡浓度产生的剂量用过去30年中的氡浓度表示,这在暴露量方面会有一定程度的不确定度,有可能降低对肺癌危险度的估计。我们进行了一项为期三年涉及55户居民的辅助研究,目的是找出室内氡水平时间、空间变化模型,并对氡致肺癌危险度的估计进行调整。氡浓度的时间变化是产生不确定度的最大来源,对室内氡进行连续几年的观测以找出其变化原因和规律很有必要。不确定度的调整使肺癌附加比值比(excess odds ratio)估算值增加50％—100％。说明用类似剂量方法进行的室内氡研究也可能低估了氡致肺癌效应。此结果对危险度评价有重要意义。     

光伏-温差混合能源的优化设计与实验研究

提出一种混合能源的设计方法,以太阳电池为温差电池的高温端热源,采用散热器为温差电池低温端散热,使得温差电池高温端和低温端形成温差,成功产生了电能.该文对光伏.温差混合能源进行优化设计和实验研究.实验结果发现,采用针肋散热器时,温差电池的开路电压大于采用肋片散热器时温差电池的开路电压;对比采用铝质散热器,采用铜质散热器时的温差电池开路电压容易出现较大波动性;采用24mm厚针肋铝质散热器时,温差电池的开路电压最大.温差电池通过DC/DC为超级电容器充电,当冷、热端温差在1.4℃时,工作电流为5.16mA,工作电压为0.41V,功率为2.11mW.     

ASP.NET在大坝安全监控Web系统开发中的应用

简要分析了大坝安全监控Web系统的发展需要，介绍了微软在其．Net架构中推出的新一代Web开发技术——ASP．NET，并通过与ASP进行对比阐明了ASP．NET的特点。最后给出了ASP．NET在大坝安全监控Web系统开发中的应用实例。     

连续催化重整装置节能分析

中国石化洛阳分公司连续催化重整装置分馏塔进料温度偏低、低温余热利用不足,在分析装置目前用能状况后,提出可通过汽提塔改冷、热进料,利用装置余热加热预分馏塔和脱戊烷塔进料以降低能耗,还可通过降低塔压、回流比和氢油比等措施进行节能。模拟结果显示,汽提塔由热进料改为冷、热进料后,其塔顶冷却负荷由187.7×104kcal/h降至62.9×104kcal/h,塔底加热炉负荷由420.5×104kcal/h降至304.1×104kcal/h,综合节能241.2×104kcal/h;在脱戊烷塔进料处增设换热器,利用汽提塔塔顶废热加热进料,脱戊烷塔塔顶冷凝负荷增加7×104kcal/h,塔底加热炉负荷减少66×104kcal/h,综合节能59×104kcal/h;在预分馏塔进料处增设换热器,利用进料/出料换热器E201壳程出口热源废热加热进料,预分馏塔塔顶冷凝负荷增加5×104kcal/h,塔底加热炉负荷减少50×104kcal/h,综合节能45×104kcal/h。     

Magnetic field effects on g-jitter induced flow and solute transport

Numerical modeling and analyses are presented of magnetic damping of g-jitter driven fluid flow and its effect on the solutal striation in a simplified Bridgman-Stockbarger crystal growth system under microgravity. The model development is based on the finite element solution of the momentum, energy and solute transport equations under g-jitter conditions in the presence of an external magnetic field. The numerical model is verified by comparison with analytical solutions obtained for a simple parallel plate channel flow driven by g-jitter in a transverse magnetic field. Simulations are carried out to study the behavior of convective flow and solutal transport induced by the combined g-jitter and magnetohydrodynamic forces. Both the idealized single frequency g-jitter force and the real g-jitter perturbation taken during space flight are considered. Results indicate that an applied magnetic field can effectively damp the velocity caused by g-jitter and help to reduce the time variation of solute redistribution. A stronger applied field is more effective in suppressing the convective flows and hence reducing concentration variation. It is found that g-jitter driven flows have the same oscillation period as the driving force with or without the applied field. However, an applied magnetic field shortens the transient period over which the flow field evolves into a quasi-steady state time harmonic oscillation after g-jitter sets in. The flow intensity increases with an increase in g-jitter magnitude but decreases with an increase in the applied field strength. The reduced convection in the liquid pool by the applied magnetic field results in a reduction of the concentration oscillation. The magnetic field is very useful in suppressing the spiking velocities that are induced by the spikes in the real g-jitter data. The damping effect is more pronounced if the magnetic field is switched on before the onset of g-jitter disturbances.