变电运维用于设备状态检修中的探讨

在进行电网的建设中,一定要保证设备的稳定,它是保证电网安全运行的基础,如果设备出现问题的话,会直接引发停电的现象。不仅影响用户的正常用电,而且给电力企业带来严重的经济损失。经济的发展推动了国家电网的建设,使其规模不断扩大,对设备的状态进行检修就显得非常的重要,并逐渐受到重视,设备状态的的检修技术应该不断的发展。本文阐述的内容主要包括变电运维技术在设备检修中的实践工作,对变电运维在设备状态检修中的优点进行分析。

探究220kV智能变电站检修二次安全检查措施

做好220kV智能变电站检修二次安全检侧工作是电力系统安全管理工作的重要内容,也是降低变电站事故发生率的重要举措,更是当下智能变电站安全维护与安全管理工作的重点与核心。本文就对220kV智能变电站检修二次安全检查的必要性及具体措施进行了分析。

Performance-based system seismic assessment for long-span suspension bridges under two-level seismic hazard

Since there are few studies on the performance-based seismic evaluation of the long-span suspension bridge system under two-level earthquake hazard in Chinese code,the developed procedure of this study can be regarded as a general program to assess the seismic performance of the overall system for long-span suspension bridges.In the procedure,the probabilistic seismic demand models of multiple bridge components were developed by nonlinear time-history analyses incorporating the related uncertainties,and the component-level fragility curves were calculated by the reasonable definition of limit states of the corresponding components in combination with seismic hazard analysis.The bridge repair cost ratios used to evaluate the system seismic performance were derived through the performance-based methodology and the damage probability of critical components.Furthermore,the repair cost ratios of the overall bridge system that was retrofitted with fluid viscous dampers for the main bridge and changed restraint systems for the approach bridges were compared.The results show that peak ground velocity and peak ground acceleration can be selected as the optimal intensity measurements of long-span suspension bridges using the TOPSIS(technique for order preference by similarity to an ideal solution).The bridge repair cost ratios can serve as accurate evaluation indicators to provide an efficient evaluation of retrofit measures.The seismic evaluation of long-span bridges is misled when ignoring the interaction of adjacent structures.However,the repair cost ratios of a bridge system that has optimum seismic performance are less sensitive to the relative importance of adjacent structures.

Debris Flow Hazard Assessment Using Set Pair Analysis Models:Take Beichuan County as an Example

Assessment of debris flow hazards is important for developing measures to mitigate the loss of life and property and to minimize environmental damage. Two modified uncertainty models, Set Pair Analysis （SPA） and modified Set Pair Analysis （mSPA）, were suggested to assess the regional debris flow hazard. A ease study was conducted in seven towns of the Beichuan county, Sichuan Province, China, to test and compare the application of these two models in debris flow hazard assessment. The results showed that mSPA only can fit for value-variables, but not for non value-variable assessment indexes, Furthermore, as for a given assessment index xi, mSPA only considers two cases, namely, when grade value increases with xi and when grade value decreases with xi. Thus, mSPA can not be used for debris flow hazard assessment but SPA is credible for the assessment because there are no limitations when using SPA model to assess the debris flow hazard. Therefore, in this study SPA is proposed for assessing debris flow hazard.

Analysis of explosion risk factor potential on coal reclaim tunnel facilities by modified analytical hierarchy process

This study focused on developing a risk assessment method for explosion at a coal reclaim tunnel （CRT） facility. The method was developed based on an analytical hierarchy process （AHP）, which is an expert system that quantifies the factors of explosion incidents, based on events and hierarchies. In this paper, the proposed model was modification from original AHP model, specifically modifying the structure from ＂alternative＇s results＂ to ＂total risk-rating＇s results＂. The total risk-rating is obtained by summing up risk-rating of each factor, where the risk-rating is a multiplication product of the risk value by the AHP weighted value. To support decision-making using the expert system, data on the real conditions of the CRT were collected and analyzed. A physical modeling of the CRT with laboratory-scale experiments was carried out to show the impact of a ventilation system in CRT on diluting the methane gas and coal dust, in order to support the quantification of AHP risk value. The criteria to evaluate the risk of explosion was constructed from six components that are： fuel, oxygen, ignition, confinement, dispersion, and monitoring system. Those components had fifty-two factors that serve as sub-components （root causes）. The main causes of explosion in CRT were found to be： mechanical ventilation failure and abnormal ventilation, breakdown of monitoring system, and coal spontaneous-combustion. Assessments of two CRT facilities at Mine A and Mine B were carried out as a case study in order to check the reliability of the developed AHP method. The results showed that the risk rating of Mine A was classified as high and Mine B was classified as medium, which is in a good agreement with the site conditions.

Capacity-based performance measurements for loading equipment in open pit mines

The purpose of this study is to develop an integrated framework for capacity analysis to address the influence of systematic hazardous factors on the haulage fleet nominal capacity.The proposed model was made to capture unexpected risks for mining equipment based upon data-driven method considering different scenarios.Probabilistic risk assessment(PRA)was employed to quantify the loss of production capacity by focusing on severity of failure incidents and maintainability measurements.Discrete-event simulation was configured to characterize the nominal capacity for mining operation.Accordingly,the system capacity was analyzed through the comparison of nominal and actual capacity.A case study was completed to validate the research methodology.The past operation and maintenance field data were collected for shovel operation.The discrete-event simulation was developed to estimate the rate of shovel nominal capacity.Then,the effects of undesirable scenarios were assessed by developing the PRA approach.The research results provide significant insights into how to enhance the production capacity in mines.The analyst gets a well judgment for the crucial elements dealing with high risk levels.A holistic maintenance plan can be developed to mitigate and control the losses.

Some Insights in Novel Risk Modeling of Liquefied Natural Gas Carrier Maintenance Operations

This study discusses the analysis of various modeling approaches such as genetic algorithms, fuzzy logic and evidential reasoning, and maintenance techniques applicable to the liquefied natural gas （LNG） carrier operations in the maritime environment. The usefulness of these algorithms in the LNG carrier industry in the areas of risk assessment and maintenance modeling as a standalone or hybrid algorithm are identified. This is evidenced with illustrative case studies.

MORE FINANCIAL Aids Needed

Weeks have past since the out- break of May 12 Earthquake in southwest China's Sich- uan province.With the pos- sibility for the missing to survive becom- ing increasingly remote,more importance should be attached to the resettlement

Migration law of heavy metal cadmium in soil-root interface systems

The distribution characteristics of heavy metals in soil-root systems have great significance for the research into soil pollution risk assessment and the phytoremediation effect. This paper takes ligustrum lucidum as an example, based on the characteristics of adsorption of heavy metals in soil by woody plants, lays out sampling points, and using software Surer for the Kiging interpolation analysis, and the horizontal migration law of heavy metal cadmium in the soil-root interface system is simulated. Through multi-model statistical regression trend analysis, the horizontal migration mechanism of cadmium in different sections is discussed. The results show that： （1） under horizontal migration law： the migration ability of Cd is weaker near the Ligustrum lucidum root （0 30 cm）; with the root extension, the migration ability of Cd gradually is strengthened, and the main range of the migration ability is 60-90 cm. In addition, its migration law follows the cubic curve mode. （2） under longitudinal migration law： based on the Kriging method, migration models Z（hi） of heavy metal Cd in any depth of hi are constructed and fit the correlation coefficient R^2〉0.95.

Risk Assessment Based on Fault Tree Analysis for Damaged Pipe Repair During Operation in Petrochemical Plant

In petrochemical plant, the in-operation repairing is usually a repairing strategy with pressured inoperation repairing for avoiding huge economic losses caused by unplanned shutdown when some slight local leakage happens in pipes. This paper studies the effects of repairing strategies on the failure probability of the pipe systems in process industries based on the time-average fault tree approach, especially the in-operation repairing strategies including pressured in-operation repairing activities. The fault tree model can predict the effect of different repairing plans on the pipe failure probability, which is significant to the optimization of the repairing plans. At first pipes are distinguished into four states in this model, i.e., successive state, flaw state, leakage state and failure state. Then the fault tree approach, which is usually applied in the studies of dynamic equipment, is adopted to model the pipe failure. Moreover, the effect of pressured in-operation repairing is also considered in the model. In addition, this paper proposes a series of time-average parameters of the fault tree model, all of which are used to calculate node parameters of the fault tree model. At last, a practical case is calculated based on the fault tree model in a repairing activity of pipe thinning.

Interleukin-6 polymorphisms modify the risk of periodontitis: a systematic review and meta-analysis

Objective： To clarify the association ofIL-6 polymorphisms and periodontitis, a meta-analysis of case-control studies and a systemic review were conducted. Material and methods： We performed a literature search using PubMed and Medline database to May 2009, with no restrictions. We also reviewed references from all retrieved articles. Six case-control studies involving 1093 periodontitis cases and 574 controls were selected for meta-analysis to assess the purported associations between IL-6 polymorphisms and the risk of periodontitis. IL-6 -174 G/C and -572 C/G polymorphisms were included in the present meta-analysis, and the association between IL-6 -6331 TIC polymorphism and the risk of periodontitis was adequately reviewed as well. Results and conclusion： The present meta-analysis indicates that the IL-6 -174 G allele could not modify the risk of chronic periodontitis, but increased the risk of aggressive periodontitis. And -572 C/G polymorphism is associated with the pathogenesis of periodontitis, including chronic periodontitis or aggressive periodontitis.

A Stochastic Model on One-Unit Repairable Systems with Multiple Degenerative States

This paper studies a maintenance model for an one-unit degenerative system with multiple failure states based on the proportional hazards and proportional reversed hazards models. The authors investigate how the variation of system configuration parameters have an impact on both operating and repair times and hence the system performance. Furthermore, the authors also derive the explicit expression for the long-run average cost per unit time. An algorithm to locate the optimal number of repairs in a renewal cycle is discussed as well.

Dangerous Frictions： The Condition of Modernity and Its Possible Repair

Whether from a liberal or a radical perspective, the transition to modernity has been hailed not only as a great achievement but as providing the cultural and institutional foundations for a good society. Yet, modernity has been driven by terrible social stsains, immense conflicts, searing social stigmas, and radical exclusion. A satisfactory social theory must conceptualize the dark side of modernity as well as the ligt. This essay identifies nine dangerous frictions inherent in modernity and also defines mechanisms for their possible repair. Critics of modernity have ignored the fact that it does provide self-correcting capacities, though these capacities are never fully developed and never adequately applied.

Fate Processes of Chlorobenzenes in Soil and Potential Remediation Strategies: A Review

Chlorobenzenes （CBs） are a group of organic pollutants that pose a high environmental risk due to their toxicity, persistence and possible transfer in the food chain. Available data in literature show that CBs axe detected in different environmental compartments such as soil, water, air and sediment. The widespread presence of CBs in the environment is related to their former extensive use in agriculture and industry. Some CBs are ranked in the list of priority pollutants by the Stockholm Convention, and their reduction or elimination from the environment is therefore of high importance. Environmental risk assessment of CBs requires knowledge on the role and importance of the main environmental fate processes, especially in soil. Furthermore, development of remediation strategies for reduction or elimination of CBs from the environment is related to the enhancement of fate processes that increase their dissipation in various environmental compartments. The main objectives of the current review were to present up-to-date data on fate processes of CBs in the soil environment and to explore possible remediation strategies for soils contaminated with CBs. Dechlorination of highly-chlorinated benzenes is the main degradation pathway under anaerobic conditions, leading to the formation of lower-chlorinated benzenes. Biodegradation of lower-chlorinated benzenes is well documented, especially by strains of adapted or specialized microorganisms. Development of techniques that combine dechlorination of highly-chlorinated benzehes with biodegradation or biomineralization of lower-chlorinated benzenes can result in useful tools for remediation of soils contaminated with CBs. In addition, immobilization of CBs in soil by use of different amendments is a useful method for reducing the environmental risk of CBs.