Wind Energy Data Analysis and Resource Mapping of Dangla,Gojjam,Ethiopia

Energy is one of the most important factors in socio-economic development.The rapid increase in energy demand and air pollution has increased the number of ways to generate energy in the power sector.Currently,wind energy capacity in Ethiopia is estimated at 10,000 MW.Of these,however,only eight percent of its capacity has been used in recent years.One of the reasons for the low use of wind energy is the lack of accurate wind atlases in the country.Therefore,the purpose of this study is to develop an accurate wind atlas and review the wind resources using Wind Atlas Analysis and Application Program in Dangla so that the best sites used for the installation of wind farms can be easily identified.Wind climatology data,vector maps,and wind turbine data were used to model the Wind Atlas Analysis and Application Program.The wind data collected from National Meteorology Survey Agency over three years were used for the analysis.Besides,vector data for the survey area was prepared using Global Mapper V20.1.In this study,the Wind Atlas Analysis and Application Program tool was used to estimate wind resources.The wind resource map was developed at an altitude of 80 m above ground level,and a horizontal axis type wind generator called(i.e.,GridStreamer Vestas V1001.8 MW)was selected from the Wind Atlas Analysis and Application Program catalog to mimic the wind farm.The results obtained from the analysis of actual wind data showed that the minimum wind speed was 0.12083 m/s while the maximum wind speed was 9.96389 m/s.At a height of 10 m a.g.l.,the mean wind speed and wind power density were 1.8 m/s and 9 w/m2,respectively.The most common wind direction was also discovered to be 210 degrees.The maximum wind speed and capacity factor were available around hills,according to the wind resource map,and the net annual energy output of the Dangla wind farm at a turbine height of 80 m a.g.l.was found to be 282.726 GWh(or,32.27 MW).The farm’s capacity factor was also discovered to be 9.54 percent,indicating that the site is rated as low potential.

Reliability Allocation of Large Mining Excavator Electrical System Based on the Entropy Method with Failure and Maintenance Data

In the design of large mining excavator electrical system,a practical reliability allocation method was introduced to allocate system level reliability requirements into subsystem and component levels. During the reliability allocation process,factors from the fault and maintenance data were only considered in reliability allocation scheme. It could avoid the disturbance from expert experiences. The entropy method was also used to obtain weights of reliability allocation indexes of large mining excavators considering different factors. Then the failure rate allocation of subsystems and components could be completed.

Machine Tool Fault Information Management System Softw are Development

In order to collect failure data conveniently and reserve reliability research data,the data collection software,the machine tool fault information management system, was developed. The method to computer numerical control( CNC) machine tool reliability data collection was introduced. Through designing the form and applying SQL Server 2008 as the database and Visual Studio 2005 as the development platform,establish the database,develop the software based on the early stage work,and realize the comprehensive statistical information, laying the foundation for further data analysis.

Interval Fault Tree Analysis of Excavator VariableFrequency Speed Control System

In consideration of the uncertainty of basic events failure rate and lack of probability statistical information in fault tree analysis( FTA) of excavator variable-frequency speed control system, the interval theory was employed and combined with conventional FTA method. The basic events failure probabilities were described by interval numbers,and the interval operators of logical gates in FTA were deduced based on interval theory. Finally,the reliability assessment of excavator variable-frequency speed control system was done by interval FTA method. The result shows that the interval FTA method is suitable for the complex system with insufficient failure data.

Reliability Analysis of Lithography Wafer Stage Based on Fuzzy Bayesian Networks

Bayesian network( BN) is a powerful tool of uncertainty reasoning. Considering the insufficient information,incorporating fuzzy probability into BN is an effective method. Fuzzy BN was used to solve this problem. In this paper,fuzzy BN was applied in wafer stage system,which was an important part of lithography. BN of wafer stage was transferred from fault tree( FT). The quantitative assessment based on fuzzy BN was carried out. The Birnbaum importance factors of basic events were calculated. Therefore,the system failure probability and the vulnerable components could be gotten.

Reliability Analysis Based on a Nonlinear Fatigue Damage Accumulation Model

A modified nonlinear fatigue damage accumulation model based on the Manson-Halford theory was presented,and the new model was developed for fatigue life prediction under constant and variable amplitude loading, which took the effects of the load interactions and the phenomenon of material's strength degradation into account. The experimental data of the 30 Cr Mn Si A and the LY-12 cz from literature were used to verify the proposed model. And from the good agreement between the experimental data and predicted results,we can see it clear that the proposed method can be applied to predicting fatigue life under different loadings.