基于条件状态和基于可靠度的桥梁维修方法的比较研究

通过探讨基于条件状态的桥梁维修优化方法,并将其与基于可靠度的桥梁维修优化方法进行比较,澄清了有关桥梁养护管理方面的一些容易混淆的概念,阐述了这两种方法的特点、优势和劣势,指出应该着力推动更适合中国桥梁养护现状的基于条件状态的维修优化方法的应用,与此同时还应关注和了解代表未来发展方向的基于可靠度的维修优化方法的最新研究与应用,并在需要时选择运用之。

基于关联规则的条件状态模糊Petri网及其在故障诊断中的应用

模糊Petri网作为一种知识表达模型,能够用于工业过程系统故障推理和诊断。然而,模糊Petri网的建立大多需要先验知识,为此限制了其广泛应用。为了能够有效利用工业生产过程数据,提出了一种基于关联规则的条件状态模糊Petri网,并将其用于工业过程故障推理与诊断。采用数据挖掘的关联规则方法提取模糊Petri网的模糊规则及置信度,通过变量间的关联分析,将影响置信度的关键主元(条件量)提取出来,建立条件状态模糊Petri网;基于极大代数的迭代算法进行动态置信度逆向推理,可以获得工业过程的故障发生概率。该方法实现了故障诊断网络的数据驱动,从而提高故障诊断的快速性与准确性,某化学反应研究表明所提方法的有效性。

摩擦提升机防滑校验状态条件的选取

本文分析了滑动极限减速度和滑动极限制动力随提升系统状态条件变化的规律，根据采用的安全制动系统不同，笔者提出简明的方法及公式来选取防滑校验所必须的状态条件。

滑移隔震系统的状态转换条件

运用几何和解析方法详细讨论了滑移隔震系统状态转换的运动学和动力学条件，该条件在滑移隔震结构地震作用下的时程响应分析中是必要的。所述方法和结论适用于更复杂滑移隔震结构的振动分析。

一种演化超图文法到状态转移系统的映射方法

运用模型检测技术验证动态演化的正确性,是近年来软件体系结构动态演化研究领域面临的一个挑战.然而,当前的方法很少考虑软件体系结构动态演化时的相关条件.针对该问题,提出用条件状态转移系统表示软件体系结构动态演化的状态模型,将软件体系结构超图映射为状态,演化规则运用映射为条件状态转移关系,给出软件体系结构动态演化的条件超图文法到条件状态转移系统的映射方法以及相应的实现算法,实现了软件体系结构动态演化的条件状态转移系统的构建,并证明了在该映射方法下,软件体系结构动态演化条件超图文法与条件状态转移系统的互模拟等价.最后通过案例分析,运用该方法以及模型检测技术,验证了软件体系结构动态演化的相关性质,从而验证了该方法的有效性.

基于有限状态自动机的服务组合模型

分析了目前服务计算的研究现状和存在的问题,在D Berardi和A Wombacher的基础上提出了一种带条件的有限状态自动机模型cFSA(Finite State Automata with condition),并给出了基于cFSA的服务理论模型.在该服务理论模型的基础上提出了一种基于有限状态自动机的服务组合形式化模型,并给出了该模型的代数性质和实现方法.

有限状态机在导弹发射安全性分析中的应用

系统从原始状态到发生灾难性事故并不一定是一蹴而就的,中间可能存在一连串的工作状态转移。基于有限状态机的完备功能逻辑提取特性,研究提出状态迁移建模分析方法,极大地降低了形式化建模语言带来的分析难度。并以空空导弹发射过程安全性分析为例,进行了说明。

基于扩展CDM模型的调度算法研究

包含混合硬实时和软实时需求的嵌入式系统需要早期的、精确的时间特性分析。因此需要一种系统高层建模方法,在对嵌入式系统进行合理准确的抽象定义的基础上,对相关高层调度算法进行分析研究。介绍的方法是在CDM模型的基础上,通过对其进行通信时间的定义及信号同步方面的规定,从而扩展CDM模型的特性及调度算法,达到更加精确的计算调度执行的目的。

三电平直流变换器混杂系统建模与控制

建立了三电平直流变换器的混杂自动机模型,并提出了相应的闭环控制算法,算法核心是使系统进入周期循环稳定的工作中并对输出电压进行调节,能够同时满足电感电流连续模式和不连续模式,具有宽负载范围。将输出电压稳压调节问题转化为离散状态转换条件选择问题,推导了离散状态转换条件。使用Matlab/Simulink中的状态流程图实现了基于混杂自动机的三电平直流变换器控制系统,并进行了详细的仿真以检验闭环控制算法的正确性。仿真结果表明,三电平直流变换器在4种工作模式下稳态性能均良好,模式切换过程中动态响应快超调小。

基于非对称具有优先级的一类逻辑环随机模型

讨论一种具有广泛性和代表性的带有优先级的逻辑环随机服务系统 :非对称型、队列容量有限、服务上额受限 .主要内容有 :系统运行特点 ;队列状态转移特性 ;队列状态转移概率近似算法 ;队列状态概率非常规算法等 .文中提出状态条件转移和状态转移组合等新概念 ;以及集中参数替代分布参数和反求等方法 .

A Condition States Assessment System for Concrete Bridges Using Neural Networks

Due to continuing aging and heavy utilization of many bridges and the limited available funds, the importance of proper bridge condition state assessment has risen recently, which is the crucial point for rational decision-making on MR&R activities. This paper presents a prototype of the concrete bridge condition state assessment system (CBCSAS) with the following sub-modules: inspection, parameter recognition, structural assessment, main cause identification and priority-to-action. And multi-layer neural networks, which may combine with fuzzy set theory or not, are performed to realize the structural assessment with embedding expert knowledge into the assessment system.

体外超声评价胃十二指肠运动功能

藤村二郎等通过研究确立了一种非侵袭性,且在接近生理条件状态下观察胃十二指肠运动的手技。方法:基於 Hausken 等的方法(Gastroenterdogy 1991;100:59～63),作者应用体外式腹式超声波。

具有通信约束的反馈辅助PD型量化迭代学习控制

本文针对网络线性系统,研究了具有通信约束的反馈辅助PD型迭代学习控制问题.信号从远程设备传输到迭代学习控制器过程中,存在数据量化与数据包丢失的情况.将数据包丢失模型描述为具有已知概率的伯努利二进制序列,采用扇形界方法处理数据量化误差,提出了一种反馈辅助PD型迭代学习控制算法.采用压缩映射法分析证明了在存在数据量化和丢失的情况下,所提控制算法依然可以保证跟踪误差渐近收敛到零.并进一步对存在初始状态偏移时所提算法的鲁棒性进行了讨论.最后,通过仿真示例,对比验证了理论结果的有效性和优越性.

VIV analysis of pipelines under complex span conditions

Spans occur when a pipeline is laid on a rough undulating seabed or when upheaval buckling occurs due to constrained thermal expansion. This not only results in static and dynamic loads on the flowline at span sections,but also generates vortex induced vibration (VIV),which can lead to fatigue issues. The phenomenon,if not predicted and controlled properly,will negatively affect pipeline integrity,leading to expensive remediation and intervention work. Span analysis can be complicated by:long span lengths,a large number of spans caused by a rough seabed,and multi-span interactions. In addition,the complexity can be more onerous and challenging when soil uncertainty,concrete degradation and unknown residual lay tension are considered in the analysis. This paper describes the latest developments and a'state-of-the-art' finite element analysis program that has been developed to simulate the span response of a flowline under complex boundary and loading conditions. Both VIV and direct wave loading are captured in the analysis and the results are sequentially used for the ultimate limit state (ULS) check and fatigue life calculation.

Characteristics of fat metabolism in skeletal muscle of rats after hypobaric hypoxic acclimation

Objective：To investigate the characteristics of fat metabolism in rat skeletal muscle after hypobaric hypoxia acclimation. Methods： Sprague-Dawley rats were divided into 3 groups randomly： control group （H0）, hypoxic 5-day group （HS）, and hypoxic 15-day group （H15）. Animals of H5 and 15 groups were exposed to hypobaric hypoxia chamber simulating 5 000 m high altitude for 5 d or 15 d respectively, 23 h per day. H0 group stayed outside of chamber The level of fatty acid oxidation and uptake, and glucose oxidation were examined, and the level of non-esterified fatty acids （NEFA）, ATP and phosphocreatine （PCr） were also assayed in rat skeletal muscles. Results： The contents of ATP and PCr in H5 group were lower than those in H0 and H15 groups （P〈0.05）, while there was no significant difference between H0 and H15. Compared with H0, the blood NEFA level in all hypoxia groups was increased significantly （P〈0.05）. The muscle NEFA level in H15 group was greatly higher than that in H0 and H5 groups. The rates of fatty acid oxidation and uptake in H15 group were significantly higher than those in H0 and H5 groups （P〈0.05）, and the rate of glucose oxidation in all hypoxia groups was significantly decreased than that in H0 group （P〈0.05）. Conclusion： It is concluded that the enhanced fat oxidation may be one of the mechanisms in the maintenance of energy homeostasis after hypobaric hypoxic acclimation.

A Fully Flexible Potential Model for Carbon Dioxide

A fully flexible potential model for carbon dioxide has been developed to predict the vapor-liquid coexistence properties using the NVT-Gibbs ensemble Monte Carlo technique(GEMC).The average absolute deviation between our simulation and the literature experimental data for saturated liquid and vapor densities is 0.3% and 2.0%,respectively.Compared with the experimental data,our calculated results of critical properties(7.39 MPa,304.04 K,and 0.4679 g?cm-3) are acceptable and are better than those from the rescaling the potential parameters of elementary physical model(EPM2).The agreement of our simulated densities of supercritical carbon dioxide with the experimental data is acceptable in a wide range of pressure and temperature.The radial distribution function estimated at the supercritical conditions suggests that the carbon dioxide is a nonlinear molecule with the C O bond length of 0.117 nm and the O C O bond angle of 176.4°,which are consistent with Car-Parrinello molecular-dynamics(CPMD),whereas the EPM2 model shows large deviation at supercritical state.The predicted self-diffusion coefficients are in agreement with the experiments.

Identification of Ni_xS_y on Industrial Spent S Zorb Sorbents by Using XPS and TPR-MS

Three industrial spent S Zorb sorbents extracted from production line were studied with XRD, TPR-MS and XPS. The characterization results of XPS and TPR-MS identified the existence of amorphous Ni_xS_y on industrial spent S Zorb sorbents, while the existing XRD quantitative analysis methods can only provide the long-range order in phase information and the grain size of Ni metal. XPS is a powerful tool to investigate the chemical states of nickel atom and the depthwise distribution of nickel species on S Zorb sorbent. Ni_xS_y and Ni metal species coexist on the industrial spent sorbents, and their percentages to total nickel slightly change with the operating conditions in the surface layer. It proves that Ni_xS_y is a stable intermediate product rather than a transition state. The information can contribute to the better elucidation of S Zorb desulfurization mechanism and offer a new direction for selectivity optimization of industrial S Zorb sorbents.

空间正义视角下城市社区公共空间治理实现路径研究——以W市J社区停车系统改造为例

在快速城市化和住房商品化的大背景下,城市社区成为居民生活的重要场所,社区公共空间所存在的开放度不够、使用权不对称及公共设施场所不足等社区公共空间不正义的现象,日益成为影响居民日常生活的普遍问题。在社区治理转向空间治理的当前,城市治理实质是“一种空间资源的生产与分配”,“空间正义”理应成为社区公共空间治理的一个重要维度。文章以W市J社区停车系统改造为例,以空间正义“状态—关系—空间性条件”的有效性内涵为基本框架,分析了J社区公共空间正义缺失及回归的治理过程,发现空间正义“状态—关系—空间性条件”的观察视角在逻辑上蕴含着社区公共空间治理目标、主体及过程的核心要件,并以此为基础,对空间正义视角下的社区公共空间治理进行了探索和思考。

Constitutive Model of Saturated Soft Clay with Cyclic Loads under Unconsolidated Undrained Condition

An equivalent visco-elastic model of saturated soft clay was studied under unconsolidated undrained (UU) condition, which can be used to evaluate the stability of ocean foundation. Cyclic triaxial compression and extension tests were conducted to study the parameters of the model. Results showed that the relationships of the damping ratio and the octahedral shear modulus with the octahedral cyclic shear strain were nearly unique, when the initial octahedral shear stress ratios of specimens were equal to 0.3, 0.5 and 0.7. The relationships of the damping ratio and the octahedral shear modulus with the octahedral cyclic shear strain determined from the cyclic triaxial compression tests were basically the same as those determined from the cyclic triaxial extension tests. Furthermore, the relationships were not related to the initial stress condition, the test stress state and the octahedral cyclic shear stress ratio. The relationships determined from the cyclic triaxial tests under no deviatoric stress were basically the same as those determined from the cyclic triaxial tests under deviatoric stress. The change of the octahedral cyclic accumulative strain with the number of cycles was unique under different tests stress states. An equivalent visco-elastic constitutive model of saturated soft clay under UU condition was initially established.