共查询到20条相似文献，搜索用时 31 毫秒
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ＨｅａｔＴｒａｎｓｆｅｒＭｅｔｈｏｄｆｏｒＳｏｌｉｄＦｌｏｗＲａｔｅＭｅａｓｕｒｅｍｅｎｔｉｎＧａｓＳｏｌｉｄＴｗｏＰｈａｓｅＦｌｏｗＹｕａｎＺｈｕｌｉｎ（袁竹林）ＬｕＺｕｏｊｉ（卢作基）（ＴｈｅｒｍｏｅｎｅｒｇｙＥｎｇｉｎｅｅｒｉｎｇＲｅｓｅａｒ... 相似文献
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The dynamics of hydraulic systems are highly nonlinear and the system may be subjected to non-smooth and discontinuous nonlinearities due to directional change of valve opening,friction,etc. Aside from the nonlinear nature of hydraulic dynamics,hydraulic servo systems also have large extent of model uncertainties. To address these challenging issues,a robust state-feedback controller is designed by employing backstepping design technique such that the system output tracks a given signal arbitrarily well,and all signals in the closed-loop system remain bounded. Moreover,a relevant disturbance attenuation inequality is satisfied by the closed-loop signals. Compared with previously proposed robust controllers,this paper's robust controller based on backstepping recursive design method is easier to design,and is more suitable for implementation. 相似文献
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在输送压力可达4.0MPa,固气比高达450kg/m3的高压气力输送试验台上,用氮气进行粉煤高压浓相气力输送试验研究.分别在不同的输送差压、煤粉湿度、浓度和速度等条件下进行了输送试验,考察操作参数对煤粉固气比等气力输送特征参数的影响,用信息熵分析试验过程中采集到的压力波动时间序列,探讨流动稳定性和流型变迁过程中信息化趋势,建立信息熵和流型之间的关系.结果表明:在输送差压增大的过程中,固气比和Shannon信息熵均增大;气体流量与Shannon信息熵和固气比之间呈现较好的规律性;不同流动形态的Shannon熵差异较大,不同流型之间的Shannon熵区分度较好.随着煤粉湿度的增大,煤粉质量流量和Shannon熵均降低.Shannon信息熵分析为研究高压浓相气力输送流型、流动稳定性及其转变特性提供了一种行之有效的方法. 相似文献
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CFD Analysis of Gas Distributor in Packed Column--Prediction of Gas Flow and Effect of Tower Internals Geometry Structure 总被引：1，自引：0，他引：1
Computational fluid dynamics (CFD) simulations were carried out on the gas flow patterns of twin-tangential annular deflector gas distributor in the absence of liquid flow in a packed column (6.4 m in diameter), and the gas flow field in the column was presented close to reality on the whole. Furthermore, after ame-lioration of this gas distributor frame, turbulence energy and turbulence energy dissipation rate were both decreased greatly.Simulation results showed that the flow pattern and the distribution of gas flow were strongly affected by the column bottom frame; the proper column bottom frame could decrease the flow pressure drop greatly. Multifold factors, such as the column bottom geometry structure and distributor structure which affects the distribution capacity, must be considered. 相似文献
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CFD Analysis of Gas Distributor in Packed Column ——Prediction of Gas Flow and Effect of Tower Internals Geometry Structure 总被引：2，自引：0，他引：2
Asoneofinternalparts,thefeedgasdistributorplaysanimportantroleinapackedcolumn.Thesmoothoperationandbetterqualityofproductsaregreatlyinfluencedbyitsperformance,especiallyinthecolumnwithlargediameter,shortpackedbedandlowpressuredrop.Duetotheimpor tanceoftheuniformityofinletgasdistribution ,itisessentialtodesignagoodfeedgasdistributor.However,fewtheoreti calandexperimentalapproacheshavebeencarriedoutinthisareasofarduetothecomplexityofthefluidflow[1 ,2 ] . Theliquidflowstructureisimprovedbyanew… 相似文献
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Cover systems are used to prevent water infiltration into a waste body. They also play an important role in controlling landfill gas transport from the waste body to the atmosphere. It is important to assess the flux of landfill gas at the surface of a cover system by considering the coupled effects of rainwater infiltration and gas transport in the cover soils. We have developed a 1D mathematical model for coupled transient gas and water transport in unsaturated cover soils. The coupled model was solved by the finite element method. Results obtained by the proposed model agreed well with experimental data. Based on the proposed solution, the influences of gas pressure, gas permeability, and the thickness of the cover soils on soil gas concentration profiles were investigated. The difference in soil gas concentration reached up to 31% as the thickness of cover increased from 1 to 2 m. Gas concentration at a depth of 0.2 m decreased by 6% as the amplitude of atmospheric gas pressure fluctuation increased from 20 to 100 Pa. The gas concentration increased by only 3% when gas permeability increased by a factor of 2 for a relatively long period of gas migration (e.g., 60 h) under the given conditions. Results suggest that both diffusion and advection should be considered when estimating gas transport in unsaturated cover soils. The numerical model can be used in the design of cover systems in relation to gas breakthrough time, breakthrough concentration, and flux. 相似文献
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The use of loess as an earthen final cover material is promising in northwest China which has an arid and semi-arid climate. A full-scale testing facility with an area 30 m long by 20 m wide was constructed at the Xi’an landfill of municipal solid wastes to investigate the performance of an inclined capillary barrier cover. The cover consisted of a compacted loess layer underlain by a gravel layer. The testing facility was well instrumented for a gas permeation test and recording of the soil conditions in terms of volumetric water content, pore gas pressure, and soil temperature. Tests were performed to measure the gas permeability of the compacted loess before and after the planting of vegetation on the cover. The field measurements demonstrate that the capillary break at the fine/coarse soil interface allows the upper compacted loess layer to retain more water, and conversely reduces its gas permeability, which is favorable for reducing landfill gas emissions. When the degree of saturation of the compacted loess was greater than 85%, the gas permeability decreased significantly with a further increment in volumetric water content. The growth of vegetation roots tended to fill the large pores in the upper loosely-compacted loess, resulting in a decrease in gas permeability of one order of magnitude. The influence of soil clods in the compacted loess on gas permeability can be one to two orders of magnitude due to an increase in pore size and a decrease in tortuosity. 相似文献
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煤气调压站压力数据采集系统 总被引：1，自引：0，他引：1
茆琦 《柳州职业技术学院学报》2009,9(1):104-107
采用微控制器MSP430和USB总线接口芯片CH375研制开发一套煤气调压站远程监控系统。该系统由安装在现场的采集记录仪、通讯模块、传感器等基站设备系统组成,用压力传感器将调压站的进口、出口的中、低压压力信号转换为电信号,记录仪控制器定时采集电信号,并处理和存储压力信号,经过处理的数据可以通过USB接口用U盘拷贝保存以用来分析。 相似文献
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蔡泽伟 《宁波大学学报(教育科学版)》1989,(1)
作者设计并制作了伪随机二进制(PRBS)信号发生器。并以PRBS信号操舵,辨识了船舶操纵运动方程的系数。用离散时间测量决定线性连续时间模型参数。给出了Mariner标准模型和一艘渔轮的辨识结果,并与标准的Nomoto K,T计算结果进行了比较,结果令人满意。 相似文献
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煤气发生炉是连轧厂最为重要的辅助设备之一,为连轧厂蓄热式加热炉提供高效、清洁的煤气,煤气发生炉的正常运行直接关系着后续的生产;为了实现对煤气发生炉进行有效的控制,设计了基于iFIX组态监控软件的实时监控系统,通过MPI电缆实时采集S7-300PLC的各种信号——煤气温度、汽包压力、饱和温度、鼓风压力等,并实现自动控制,实时显示和超限报警,达到了预期的设计目标。 相似文献
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Students tend to have a poor understanding of the concept of gas pressure. Usually, gas pressure is taught in terms of the
various formulaic gas laws. The development of the concept of gas pressure according to the early Greeks did not include the
concept of a vacuum. It was not for another 2000 years that Torricelli proposed that a vacuum can exist and that he was able
to produce a vacuum above a column of mercury. However, the existence of a vacuum continued to be a contentious issue for
at least another 100 years. During this time the behavior of gases was studied by Boyle, Amontons, Gay-Lussac, Daniel Bernouli,
Charles, and Dalton. In the 19th century gas behavior was revisited and studied from the molecular level through the work of Graham, Maxwell, Boltzmann, and
van der Waal. The stories of conflicting theories and the development of the concept of gas pressure gives students an increased
appreciation for the nature of science and helps them with conceptual understanding of the concept of gas pressure. 相似文献
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运用fluent软件对不同气膜厚度的螺旋槽干气密封内部微间隙三维流场进行数值模拟,得到它们流场的压力分布。通过不同厚度的气膜所产生的动压来获得它们气膜推力,再利用最小二乘法则拟合得到了气膜推力关于气膜厚度的解析式,最后求得气膜刚度,以最大气膜刚度为目标,对螺旋槽的槽深和螺旋角进行了优化。结果表明:气膜刚度是关于气膜厚度的负指数函数;在本例中,当槽深为7.5μm、螺旋角为75°时气膜刚度最大,该优化程序为干气密封的优化设计提供理论基础。 相似文献
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应用确定性混沌分析技术,初步研究了下喷自吸环流反应器内气－液两相流动的时序压力波动的局部混沌特性．结果发现,在本文实验条件下,该反应器内局部最大李雅普诺夫指数值均大于零,并且呈现出与局部分形维数类似的分布规律．这些结果表明,该反应器内的流动行为呈现混沌特性,可以应用诸如局部最大李雅普诺夫指数和局部分形维数等局部非线性特征参数从更深层上揭示多相反应器内的流动特性,例如流区过渡及流动结构等． 相似文献
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学习过程监控是远程教育的关键环节。学习者在不同学习状态下,脑电波、脉搏、血压、皮温等生物信号会有所不同。基于生物信号采集的远程学习过程监控系统,利用生物传感器采集学习者在线学习时的生物信号,一方面将不同学习者呈现出的生物信号特征分类,建立生物信号分类数据库;另一方面,将动态采集的学习者生物信号通过蓝牙等无线传输方式输入学习终端,再通过Internet输入到远程学习管理中心,通过系统分析软件将采集到的生物信号与学习者生物信号分类数据库进行对比,以获得学习者的实时学习状态,为教师干预和学习者学习提供及时、有针对性的支持服务。基于眼动信号监控学习者疲劳状态的实验证明,利用生物信号采集技术对远程学习过程进行监控,有助于管理者掌握学习者的学习状态,并据此提供个性化学习过程和学习资源支持服务。 相似文献
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潘玉灼 《泉州师范学院学报》2002,20(6):33-36
应用热力学理论以及费米积分的特性，导出理想费米气体焦汤系数的解析表达式，详细讨论了低温下费米气体的定压热容和焦汤系数，并阐明了费米气体的量子本性对焦汤效应的影响，结果表明理想费米气体的焦汤效应为负效应。 相似文献
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郭本华 《安顺师范高等专科学校学报》2009,11(5):90-93
复杂网络传播动力学模型可以用Fokker--Plank方程来描述。在网络结构参数、相互作用系数发生涨落时,网络的Fokker—Plank方程的解与确定性方程的解明显不同。表明,参数的涨落是影响网络传播的重要因素。 相似文献