虚拟重联条件下地铁列车追踪运行性能衡量

虚拟重联是一种使列车以编队方式在轨道上追踪运行的技术,从而提高城市轨道交通运营的灵活性和提升线路的通过能力.本文围绕虚拟重联运行仿真和性能衡量,探讨了虚拟重联技术需要的安全制动模型,针对车站瓶颈区域提出了虚拟重联模型和车站追踪改进模型.通过数值计算和计算机仿真建模的方法,对提出的模型进行了仿真验算,结果表明:车站追踪改进模型与相对移动闭塞通过能力相当,虚拟重联模型通过能力最大;系统受到初始延误后,虚拟重联模型的延误恢复能力最强.

探析计算机应用系统性能测试技术及应用

随着计算机技术和信息技术在各行业领域中的广泛应用,促进了各行业企业的转型升级、生产效率的有效提升,计算机应用系统结构也日益复杂化。现阶段计算机应用系统中各软硬件性能直接影响着系统数据处理效果,加之用户数量的日益增多、操作行为的多样化,对计算机系统的要求也越来越高,这就需要对计算机应用系统性能不断优化以满足用户的实际需求。本文对计算机应用系统的性能衡量指标进行了分析,对计算机应用系统性能测试技术应用策略进行了探讨。

图像质量评价研究综述

图像质量评价是一个经典的研究课题,其目标是设计算法,给出和人的主观感受相一致的评价值。在许多图像处理的应用领域中,图像质量评价算法都具有重要意义。目前已提出多种评价算法,本文对这些算法进行综述。首先描述图像质量的主观评价方法,它给出科学、稳定的主观评价值;其次对各种客观评价算法进行分类介绍,重点探讨了各类算法的思路及特点;然后详细描述了衡量算法性能的定量指标;最后总结了图像质量评价算法研究的发展趋势。

基于张量分解的智能电表电压数据缺失填补算法

为了降低配电台区智能电表采集的电压监测数据缺失给电力监测、供电质量分析精确度所带来的负面影响,针对传统算法利用二维数据分布特征填补数据缺失的不足,提出了一种基于张量分解的填补算法来估计智能电表电压数据的部分缺失。首先随机抽取一条线路相邻台区智能电表连续7天的电压数据样本,构建三阶张量模型,分析张量数据各维度间的相关性;然后基于电压数据各维度间的相关性,通过CANDECOMP-PARAFAC分解(CP分解)过程,将张量分解成3个一维的因子矩阵,利用交替最小二乘法进行因子矩阵的迭代更新,达到预设的最大迭代次数时,即可得到缺失电压的估计值。实验结果表明,基于张量分解的电压缺失数据填补算法能够充分利用电压数据在各维度间的相关性,填补衡量电力系统电能质量时有价值的缺失参数。在65%至80%缺失率下,缺失值填补误差显著低于传统的K近邻(K-nearest neighbor,KNN)缺失值填补算法,有效解决了高缺失率下的电压数据缺失问题。三阶张量建模为处理智能电表电压数据缺失问题提供了新的角度。

Isoflurane preserves energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation

AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane. METHODS: Hepatocytes freshly isolated from fed rats were suspended in Krebs-Henseleit buffer, and incubated in sealed flasks under O2/CO2 or N2/CO2 (95%/5%, V/V) for 30 or 60 min, followed by 5 or 10 min of reoxygenation, with an added volatile anesthetic or not. ATP, ADP, and adenosine monophosphate in hepatocytes were determined by high performance liquid chromatography, and energy charge was calculated. RESULTS: During 30 min of anoxia, the energy charge and total adenine nudeotide steadily increased with the isoflurane dose from 0 to 2 minimum alveolar anesthetic concentration (MAC), then decreased from 2 to 3 MAC. In short incubations (30-35 min) at 1 MAC isoflurane, energy charge modestly decreased during anoxia, which was partially prevented by isoflurane and completely reversed by reoxygenation, and total adenine nudeotide did not decrease. In long incubations (60-70 min), both energy charge and total adenine nudeotide greatly decreased during anoxia, with partial and no reversal by reoxygenation, respectively. Isoflurane partly prevented decreases in both energy charge and total adenine nudeotide during anoxia and reoxygenation. In addition, 1 MAC isoflurane obviously increased ATP/ADP, which could not be changed by 1 MAC halothane. CONCLUSION: Isoflurane partially protects isolated hepatocytes against decreases in both energy charge and total adenine nudeotide during short (reversible) or long (irreversible) anoxia.

Determination of r Factor of Kalbach-Mann Systematics for Energy Balance

Kalbach Mann systematics is a very useful formula to discrete the double-differential cross sections of emitted particles. However, the energy balance by using this systematics is still a task to be studied. In the form of Legendre polynomial expansion the energy balance has been proved analytically. In terms of this approach, the formula to determine the prc-equilibrium fraction r factor of Kalbach Mann systematics has been obtained for keeping energy balance strictly. This formula could be straightforwardly applied for describing the double-differential cross sections of all projectile types in the eontinuum spectrum emissions. It indicates that Legendre expansion coefficient with l= 1 is the key term in the energy balance.

Implementation Study of Dynamic Load Balancing Algorithm of Parallel Tree Computation on Clusters of Heterogeneous Workstation

The rapid growth of interconnected high performance workstations has produced a new computing paradigm called clustered of workstations computing. In these systems load balance problem is a serious impediment to achieve good performance. The main concern of this paper is the implementation of dynamic load balancing algorithm, asynchronous Round Robin (ARR), for balancing workload of parallel tree computation depth-first-search algorithm on Cluster of Heterogeneous Workstations (COW) Many algorithms in artificial intelligence and other areas of computer science are based on depth first search in implicitty defined trees. For these algorithms a load-balancing scheme is required, which is able to evenly distribute parts of an irregularly shaped tree over the workstations with minimal interprocessor communication and without prior knowledge of the tree’s shape. For the (ARR) algorithm only minimal interprocessor communication is needed when necessary and it runs under the MPI (Message passing interface) that allows parallel execution on heterogeneous SUN cluster of workstation platform. The program code is written in C language and executed under UNIX operating system (Solaris version).

Theoretical and Experimental Study of a Cylindro-Parabolic Solar Collector

This article outlines the theoretical and experimental performance studies of a cylindro-parabolic solar collector. The theoretical study consists on the establishment, through mass and energy balances, of a mathematical model to control the exiting temperature of the heating fluid as well as the temperatures of the absorber and the glass. The experimental level investigates the influence of the solar absorber tube diameter on the performances of the driving device. Several experiments were made in order to know the possibility to reach temperatures being able to ensure for example the ammonia vaporization in the generator of a solar absorption refrigeration system. These experiments were carried out under various operating and climatic conditions. The results are presented and discussed.

A Numerical Method for Calculating Interior Ballistics of Electrothermal Accelerator

Electro-thermal accelerator uses high-voltage arc energy to heat the actuating medium, it being made from low-molecular weight material. Projectile acceleration is achieved by expansion of the actuating medium. Numerical method for calculating interior ballistics uses Lagrangian coordinates there the conservation of momentum and the energy balance are solved. A statement of the energy balance reflects the second law of thermodynamics. Lagrangian different grid and scheme for numerical calculation were used. Fully explicit scheme was employed. The solving includes two stability conditions： Courant and shock （artificial viscosity）. Numerical results were compared with the experimental research for pressure in the barrel in electro-thermal accelerator.

Differential effects of energy balance on experimentally-induced colitis

AIM： To characterize the influence of diet-induced changes in body fat on colitis severity in SlVlAD3-/- mice.METHODS： SMAD3-/- mice （6-8 wk of age） were ran- domly assigned to receive a calorie restricted （30% of control; CR）, control （CON）, or high fat （HF） diet for 20 wk and were gavaged with sterile broth or with Helicobacter hepaticus （H. hepaticus） to induce colitis. Four weeks after infection, mice were sacrificed and the cecum and colons were processed for histological evaluation.RESULTS： Dietary treatment significantly influenced body composition prior to infection （P 〈 0.05）, with CR mice having less （14%±2%） and HF-fed mice more body fat （32% ± 7%） compared to controls （22%±4%）. Differences in body composition were associated with alterations in plasma levels of leptin （HF 〉 CON 〉 CR） and adiponectin （CON 〉 HF 〉/ CR） （P 〈 0.05）. There were no significant differences in colitis scores between CON and HF-fed mice 4 wk post-infection. Consistent with this, differences in proliferation and in- flammation markers （COX-2, iNOS）, and infiltrating cell types （CD3^＋ T lymphocytes, macrophages） were not observed. Unexpectedly, only 40% of CR mice survived infection with H. hepaticus, with mortality observed as early as I wk following induction of colitis.CONCLUSION： Increased adiposity does not influence colitis severity in SMAD3-/- mice. Importantly, caloric restriction negatively impacts survival following pathogen challenge, potentially due to an impaired immune response.

The Energy Balance of the Electro-Hydraulic Linear Actuation System

The variable gas exchange valve actuation systems have been developed in order to improve the efficiency of the combustion process. The electro-hydraulic valve actuation （EHVA） systems have good power to weight ratio, high maximum force and good controllability. The disadvantages are limited frequency bandwidth and energy recovery. Each component of the EHVA system has certain energy consumption, which is characteristic to the component. In this study the power consumptions of the components are investigated by means of the simulation. The investigated components are a hydraulic pump, a hydraulic accumulator, a control valve, and hydraulic lines connecting the components. The pressure losses caused by the oil flow are most significant in the control valves, 50-60% of the total energy consumption. If the stored kinetic energy of the actuator and moving oil masses could be reused, the energy consumption could be up to 25% better.

Modeling of Transient Thermal Conditions in Cutting

The thermal conditions like the temperature distribution and the heat fluxes during metal cutting have a major influence on the machinability, the tool lifetime, the metallurgical structure and thus the functionality of the work piece. This in particular applies for manufacturing processes like milling, drilling and turning for high-value turbomachinery components like impellers, combustion engines and compressors of the aerospace and automotive industry as well as energy generation, which play a major role in modern societies. However, numerous analytical and experimental efforts have been conducted in order to understand the thermal conditions in metal cutting, yet many questions still prevail. Most models are based on a stationary point of view and do not include time dependent effects like in intensity and distribution varying heat sources, varying engagement conditions and progressive tool wear. In order to cover such transient physics an analytical approach based on Green＇s functions for the solution of the partial differential equations of unsteady heat conduction in solids is used to model entire transient temperature fields. The validation of the model is carried out in orthogonal cutting experiments not only punctually but also for entire temperature fields. For these experiments an integrated measurement of prevailing cutting force and temperature fields in the tool and the chip by means of high-speed thermography were applied. The thermal images were analyzed with regard to thermodynamic energy balancing in order to derive the heat partition between tool, chips and workpiece. The thus calculated heat flow into the tool was subsequently used in order to analytically model the transient volumetric temperature fields in the tool. The described methodology enables the modeling of the transient thermal state in the cutting zone and particular in the tool, which is directly linked to phenomena like tool wear and workpiece surface modifications.

Low velocity impact response and energy absorption behavior on glass fibre reinforced epoxy composites

A study was undertaken to determine the effects of several key geometry influencing factors on the impact response and energy absorption behavior of the glass fibre reinforced epoxy composites at low and intermediate energies.The energy-balance model was employed for characterising the energy absorption behavior and it depends strongly on the plate diameter and thickness.In addition,the damage vs.energy and force maps is effective in monitoring damage growth within the composite panel.The response of the composite laminate configurations characterized by different stacking sequences subjected to low velocity impacts with different impact energies have also been studied to estimate the damage initiation of composites.

Experimental investigation on diesel engine's waste heat capacity under mapping characteristics

Waste heat recovery for internal combustion engine(ICE)has been considered as an important strategy to improve efficiency and promote fuel economy,thus alleviating the problems of energy shortage and environmental pollution.This paper investigates the characteristics of various kinds of waste heat energy,namely,waste heat in exhaust,cooling water and charge air,over the engine’s whole operating region.Based on the energy balance experiments,the energy distribution of a conventional heavy-duty diesel engine is obtained under mapping characteristics.According to exergy analysis,the energy recovery potential for waste heat is studied as well.The experimental results indicate that exhaust energy increases with engine speed and load,while cooling water energy is more sensitive to load,especially at low and middle speed.Charge air energy,on the other hand,mainly counts on speed rather than load.Exhaust energy possesses the highest recovery potential in terms of both quantity and quality.Through waste heat recovery,a dramatic improvement in engine efficiency is achievable,actually,the maximum value can amount to 60%or even more.

Effect of Soil Water Repellency on Energy Partitioning Between Soil and Atmosphere:A Conceptual Approach

Water repellency(WR) is a phenomenon known from many soils around the world and can occur in arid as well as in humid climates;few studies,however,have examined the effect of soil WR on the soil-plant-atmosphere energy balance.The aim of our study was to estimate the effects of soil WR on the calculated soil-atmosphere energy balance,using a solely model-based approach.We made out evapotranspiration to have the largest influence on the energy balance;therefore the effect of WR on actual evapotranspiration was assessed.To achieve this we used climate data and measured soil hydraulic properties of a potentially water-repellent sandy soil from a site near Berlin,Germany.A numerical 1D soil water balance model in which WR was incorporated in a straightforward way was applied,using the effective cross section concept.Simulations were carried out with vegetated soil and bare soil.The simulation results showed a reduction in evapotranspiration of 30-300 mm year^(-1)(9%-76%) at different degrees of WR compared to completely wettable soil,depending on the severity degree of soil WR.The energy that is not being transported away by water vapor(i.e.,due to reduced evapotranspiration) had to be transformed into other parts of the energy balance and thus would influence the local climate.

Nonlinear vibration of an elastically restrained tapered beam

This paper presents the analytical simulation of an elastically restrained tapered cantilever beam using the energy balance method(EBM) and the iteration perturbation method(IPM).To assess the accuracy of solutions,we compare the results with the harmonic balance method(HBM).The obtained results from EBM and IPM are in excellent agreement with HBM results.The results show that both methods can be easily extended to other nonlinear oscillations and it can be predicted that both methods can be found widely applicable in engineering and physics.

Global Existence of the Equilibrium Diffusion Model in Radiative Hydrodynamics

This paper is devoted to the analysis of the Cauchy problem for a system of PDEs arising in radiative hydrodynamics. This system, which comes from the so-called equilibrium diffusion regime, is a variant of the usual Euler equations, where the energy and pressure functionals are modified to take into account the effect of radiation and the energy balance containing a nonlinear diffusion term acting on the temperature. The problem is studied in the multi-dimensional framework. The authors identify the existence of a strictly convex entropy and a stability property of the system, and check that the Kawashima-Shizuta condition holds. Then, based on these structure properties, the wellposedness close to a constant state can be proved by using fine energy estimates. The asymptotic decay of the solutions are also investigated.

Three-Dimensional Stability Analysis of Excavation Using Limit Analysis

The theory of limit analysis is presented for a three-dimensional stability problem of excavation. In frictional soil, the failure surface has the shape of logarithm helicoid, with the outline profile defined by a log- spiral curve. The internal dissipation rate of energy caused by soil cohesion and gravity power of the failure soil is obtained through theoretical derivation. By solving the energy balance equation, the stability factor for the excavation is obtained. Influence of the ratio of width to height, the slope angle, and the top angle on the stability is examined. Numerical results of the proposed algorithm are presented in the form of non dimensional graph. Examples illustrate the practical use of the results.