Mixing in the surface boundary layer of a tropical freshwater reservoir

A combined observational-modeling study was conducted to investigate turbulence mixing, and the relation to surface forcing, in the surface boundary layer (SBL) of a tropical, high-altitude, freshwater reservoir. A suite of vertical profiles of temperature microstructure, collected at three different stations of one-day duration each, provided estimates of dissipation rates of turbulence kinetic energy, , and temperature variance, χ. Numerical simulations of and χ, using state-of-the-art, public domain, two-equation turbulence closure models, compared favorably with the observations and reproduced the dynamics of daytime wind mixing as well as the vertical and temporal turbulence structure during nighttime convective conditions.Two independent estimates of vertical eddy diffusivities in the stably stratified (daytime) SBL, computed from the microstructure measurements, agreed closely, and the near surface heat and buoyancy fluxes, computed from the diffusivities, were similar to those computed independently from surface meteorology. Model generated eddy diffusivities agreed closely with the observed values, except those generated by K profile parameterization (KPP) model simulations. The good agreement provides confidence that nutrient fluxes in the SBL may be accurately computed from the models when forced with regularly measured surface meteorological parameters. The consequences are important for estimation of daily primary productivity rates in the euphotic zone and the ability to predict algal blooms such as those observed in the present reservoir.     

Finite-volume simulation method to predict the performance of a sailing boat

 A flow-simulation method was developed to predict the performance of a sailing boat in unsteady motion on a free surface. The method is based on the time-marching, finite-volume method and the moving grid technique, including consideration of the free surface and the deformation of the under-water shape of the boat due to its arbitrary motion. The equation of motion with six degrees of freedom is solved by the use of the fluid-dynamic forces and moments obtained from the flow simulation. The sailing conditions of the boat are virtually realized by combining the simulations of water-flow and the motion of the boat. The availability is demonstrated by calculations of the steady advancing, rolling, and maneuvering motions of International America's Cup Class (IACC) sailing boats. Received: December 25, 2001 / Accepted: March 26, 2002     

关于服装工效学的研究—对人体及服装舒适性评价指标的探讨

根据笔者多年来的实际工作经验，把人体－服装－环境作为一个系统，即服装工效学的观点，着重介绍了人体及服装舒适性的评价测试指标，主要指标是：（1）体温，（2）热平衡差；（3）代谢产热量；（4）体表面积；（5）出汗量，（6）心率，（7）服装舒性性指标PPD与PMV等7项，并对实际应用进行了探讨，从而为全面研究服装的功能，为人们在不同的环境气候条件下，穿着合适的服装提供了可靠的评价方法。     

边界元法在探测黄土洞穴方面的应用

边界元法(BEM)作为一种新的有突出优点的数值计算方法,正在不断地开辟新的应用领域。本文通过给出黄土洞穴问题的三维稳定电流场的定解问题,利用格林公式导出边界积分方程。并将其计算结果与勒让德(Legendre)级数解进行对比,评价该方法的计算精度。同时,运用BEM 大量地计算了各种不同参数的视电阻率(p_s)曲线。从而对电阻率法的联合剖面装置参数进行了优选。     

土工格栅加筋土体界面性能综述

近几年国内外在土工格栅加筋土体界面性能研究方面取得了一定的进展,就试验设备、研究内容和方法以及取得的有规律性的成果进行分析和总结,并提出需要进一步研究的几个方面。     

浅谈武钢工业港排水箱涵基坑支护设计

工程建设中,基槽开挖和边坡支护稳定,是建设成败的关键。该工程根据场地地形地质条件划分工程区域,根据各分段断面特征分别进行边坡支护设计,采用了多种不同支护方式对开挖边坡进行支护,并对其稳定性进行安全评价。基坑开挖前在基槽沿线开挖探坑,进一步了解并核实不同工区的地质情况,按照各个探坑的实际情况与相应的地质勘察报告综合分析后,对设计方案进行优化,并提出不同的施工准备,保证工程安全、顺利地进行。     

弹性地基板在移动荷载作用下的振动分析

建立了移动荷载作用下，弹性半卒间地基上四边弹性支撑有限板的一种新型力学模型，并以单位力作用下的简支矩形板为基本系统，通过简化约束，利用互等功定理及变分法原理，求解出了在移动荷载作用下该矩形板的解析解。根据机场工程中实测的道面板弯沉值，利用此解析解反算出了板边弹性支撑的刚度系数。通过该方法就可以确定刚性道面板间的接缝传荷能力，从而使道面板的设计更加经济合理。     

路桥过渡段沉降控制指标的研究

桥头跳车是由于桥台和台背路基产生差异沉降而造成的,因此路桥过渡段容许差异沉降是预防桥头跳车的一个关键问题。本文参照汽车平顺性评价方法,建立3个自由度的车辆-人体-座椅的振动模型,对台背不同差异沉降对行车舒适性的影响进行分析,并结合相关文献资料的结果,提出了路桥过渡段沉降的控制标准。     

负压非均匀分布边界条件下砂井地基固结解析

基于浅表层超软弱淤泥地基真空预压处理技术的特点,建立了浅表层超软弱淤泥砂井地基的固结理论。该理论的解析解考虑了浅表层超软弱淤泥地基真空预压处理技术所存在的负压非均匀分布的边界条件问题,更接近工程实际情况,计算精度可满足工程要求。     

基于舒适性的高原列车空调系统控制模式研究

运行在青藏线上的空调列车,其车内环境受车外环境条件影响很大.在分析了现运行青藏线空调列车空调系统控制过程的基础上,从舒适性的角度提出了同时考虑车内新风量需求、氧气浓度限值、污染物浓度控制、舒适性等因素的列车空调系统及制/供氧系统控制方案.该系统除了考虑人体因素和车内环境因素对舒适性的影响,还将车外大气压和车内氧浓度归入舒适性的影响因素,实现了舒适与节能的统一.研究对现运营的青藏线列车空调系统的技术改进、运行管理、车内空气品质改善有重要的理论指导意义.