大型地下洞室群动态安全可视化系统研发及应用

针对水电站大型地下洞室群施工过程中结构安全的动态性和复杂性,基于可视化引擎VTK强大的三维图形处理能力,开发了大型地下洞室群动态安全可视化系统。将监测数据、施工过程状态信息和数值分析结果与VTK可视化系统有机融合,在建立的大型地下洞室群数值仿真模型的基础上,通过建立施工过程状态与数值仿真模型的动态耦合仿真方法,实现动态展示和实时交互式查询可视化模型信息,并实现了地下洞群的施工过程与其结构安全状态三维动态耦合可视化。该系统为水电站大型地下洞室群提供了一个直观交互式的信息可视化管理平台及安全监控平台,具有一定的工程意义和应用价值。     

流域三维地形仿真及洪水演进动态模拟

以VisualC 为编程基础平台,利用OpenGL和GIS技术,建立了流域三 维地形仿真系统;采用三维网格逼近的方法生成真实的三维地形,并在其上建模,实现了包括洪水淹没、推进的动态模拟仿真可视化技术, 初步建立了洪水演进仿真的框架。     

BIM技术在水利水电工程可视化仿真中的应用

为简化水利水电工程施工可视化仿真系统的开发及应用,提出基于建筑信息模型(BIM)的可视化仿真方法,构造了工程建筑物的三维数字模型,并根据Navisworks软件的数据组织形式,充分利用其可视化、四维模拟功能及应用程序接口API,实现了工程施工过程的动态演示及仿真信息的可视化查询。工程实例验证了该方法的实用性及优势。     

重力坝三维可视化辅助设计系统

针对目前重力坝辅助设计软件的标准化和通用性不强的问题,依据混凝土重力坝设计规范,基于可视化技术、三维实体建模技术、xml数据库技术和DXF文件技术,采用面向对象方法设计实现了重力坝三维可视化辅助设计系统。该系统将三维绘图与AutoCAD图形输出集成到系统内部,实现了坝体三维可视化操作,提高了重力坝辅助设计软件的通用性和操作性。     

基于X3D的数字流域可视化仿真研究

基于X3D构建了数字流域三维场案，并在此基础上设计并实现了一个网上仿真系统原型，以适应数字流域在web上扩展的需要。该系统具有良好的平台无关性，可以提供整个流域2D图形和特定区域3D图形的网络展示以及相关信息的点击查询。     

基于监测信息的坝体三维可视化及系统集成

为全面了解大坝安全监测信息,迅速发现数据中隐含的特征,预警可能出现的结构异常及分析评判坝体结构安全状态,提出以可视化技术仿真坝体实际空间监测信息,实现了三维时空中的数据场量的可视化和人机交互功能,设计开发了可视化的大坝安全监测系统.运行实践表明,可视化系统更直观表现了坝体信息,为坝体监控、分析、评判提供了形象的描述和有...     

流化床炉内温度场的虚拟表示

介绍了以VC^ 6．0为平台，结合Intra3D技术，研究流化床锅炉燃烧温度场的三维动态可视化虚拟表示．在流化床锅炉燃烧温度场的动态全面仿真的基础上，运用计算机图形学的理论和方法，利用数字仿真的大量数据，借助粒子运动系统的规律，建立流化床虚拟火焰，并实现动态显示和基本的人机交互，该技术的研究，可拓展热力系统性能研究的思路，弥补试验或中试研究投资大和周期长的不足，开拓出新型热力系统的虚拟再现研究手段。     

洪水演进模拟仿真系统研制的技术和目标分析

作为“数字流域”工程建设重要组成的洪水演进仿真系统的研制,是复杂的专题应用系统的开发;系统的研制必须以面向对象的系统开发技术为指导,以计算机可视化技术和空间信息技术为支撑;在深入的系统分析基础上,确定了系统的开发目标。     

基于WebGIS的分布式水文模型构建研究

为实现多用户在线参与流域管理、提高流域管理效率,构建了基于WebGIS和分布式水文模型的面向服务的流域水资源管理系统Web-ESSI,采用.NET三层分布式架构和MVC设计模式,以ArcGIS Server为WebGIS构建平台、分布式水文模型ESSI为水文过程模拟工具、SQL Server为数据管理系统,结合Visual C#2005面向对象编程语言实现系统搭建,并应用于山东省临沂流域,实现了多用户同时查询水资源信息、水文过程动态模拟和空间可视化分析。     

架空配电线路可视化信息管理系统的设计与开发

针对传统的架空配电线路信息管理方法的缺陷,利用3ds Max、VB和Access 2003数据库,基于科学、系统、可视化的管理理念,开发了架空配电线路信息管理系统。该信息管理系统根据功能需求划分为用户管理、系统查询、图像显示、文本显示、信息添加五个功能子模块,采用3ds Max制作三维可视化模型和二维三视图,用Access设计数据库,用VB制作界面、编写函数、过程和全局变量,可为管理者提供方便直观的服务和交互式操作,提高了架空配电线路运行单位的管理水平。     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

Decomposition of limestone in a solar reactor

The thermal decomposition of limestone has been selected as a model reaction for developing and testing an atmospheric open solar reactor. The reactor consists of a cyclone gas/particle separator which has been modified to let the concentrated solar energy enter through a windowless aperture. The reacting particles are directly exposed to the solar irradiation. Experimentation with a 60 kW reactor prototype was conducted at PSI's 90m² parabolic solar concentrator, in a continuous mode of operation. A counter-current flow heat exchanger was employed to preheat the reactants. Eighty five percent degree of calcination was obtained for cement raw material and 15% of the solar input was converted into chemical energy (enthalpy).The technical feasibility of the solar thermal decomposition of limestone was experimentally demonstrated. The use of solar energy as a source for high-temperature process heat offers the potential of reducing significantly the CO₂ emissions from lime producing plants. Such a solar thermochemical process can find application in sunny rural areas for avoiding deforestation.