Papers by Keyword: Performance Indicators

Abstract: Construction projects are typically carried out under high-risk conditions and managers are forced to handle a great deal of uncertainty during the construction process. The Earned-Value Analysis is a control technique that provides early warnings of performance by quantitative measures, enabling timely corrective actions to ensure project success. This method was developed to control and adjust the project's baseline during execution. The objective of this article is to discuss the main implications of using EVA in construction projects through a case study. Results proved the applicability of the method in the construction industry. The various indicators generated allow managers to make forecasts for optimistic, realistic, and pessimistic scenarios, having the opportunity to correct any deviations in advance. In addition to forecasts, benchmarking data can be generated for the planners or companies responsible for the project, thus increasing the accuracy of future projects.

Abstract: X-ray spectroscopic microanalysis was used to determine the concentration of titanium on the surface of the wear spot of a silicon carbide crystal during micro-scratching and the concentration of silicon on the treated surface after grinding by a wheel of silicon carbide. The wear resistance and grinding coefficient of titanium alloys under micro-scratching with single crystals and grinding with wheels made of corundum, silicon carbide, cubic boron nitride and diamond were determined. The morphology of the treated surface and the regularities of changes in the indicators of the grinding process of titanium alloys with circles of various characteristics were studied. The features of the process of grinding titanium alloys using various lubricants and coolants are shown. The influence of the characteristics of the abrasive tool and grinding modes on low-cycle fatigue on the operation of flat and round grinding of samples made of titanium alloys VT9 and VT22 was studied. The influence of abrasive material, grinding speed, feed and sparkout during finishing on low-cycle fatigue was analyzed. Based on the research, recommendations were given for choosing a rational characteristic of the abrasive tool and processing modes.

Abstract: Overall effectiveness (OE) for CNC machine tools is a metric sistem for assessing the production obtained performance. To optimize OE is necessary to determine the performance indicators [1,2], identifying and correcting the non-values ​​[3,4,5]. In this paper we propose new methods for CNC machine tools OE improvement, through IFA (Information Focus Action) analysis of production losses, during milling machine Wissner Wi3020 type. Comparison of real OE diagram with the theoretical one, provides information about the real losses associated with sub-processes. Also, root-cause analysis of performance losses, leading to the generation of new ways to improve the CNC machine tools OE.

Abstract: Hourly measured PM₁₀ concentration at eight monitoring stations within peninsular Malaysia in 2006 was used to conduct the simulated missing data. The gap lengths of the simulated missing values are limited to 12 hours since the actual trend of missingness is considered short. Two percentages of simulated missing gaps were generated that are 5 % and 15 %. A number of single imputation methods (linear interpolation (LI), nearest neighbour interpolation (NN), mean above below (MAB), daily mean (DM), mean 12-hour (12M), mean 6-hour (6M), row mean (RM) and previous year (PY)) were calculated to fill in the simulated missing data. In addition, multiple imputation (MI) was also conducted to compare between the single imputation methods. The performances were evaluated using four statistical criteria namely mean absolute error, root mean squared error, prediction accuracy and index of agreement. The results show that 6M perform comparably well to LI. Thus, this show that the effect of smaller averaging time gives better prediction. Other single imputation methods predict the missing data well except for PY. RM and MI performs moderately with the increasing performance in higher fraction of missing gaps whereas LR makes the worst methods for both simulated missing data percentages.

Abstract: The analysis of all kinds of selected chemicals, mixed starch was donethrough a specific process and orthogonal experiments. The best proportion ofthe new type of surface sizing agent was prepared through the glue applicationexperiments, testing paper physical properties. The results showed that thebest formula of surface sizing agent including borax, sodium silicate,anhydrous sodium sulfate, ferrous chloride which ratio is 3:4:2:1. At the sametime modifying agent was added so that the stable performance can be obtainedfrom the solid surface sizing agent. Homemade solid surface sizing agent canmake paper greatly improve the sizing degree, increased by 50.9%, the stiffnessof the tear strength increased by 56.7%, folding degrees increased by 53.0%.Compared with the surface sizing agent market, various aspects index improvedsignificantly.

Abstract: Almost all real life datasets consist missing values. These are usually due to machine failure, routine maintenance, changes in siting monitors and human error. The occurence of missing values requires special attention on analysing the data. Incomplete datasets can cause bias due to systematic differences between observed and unobserved data. Therefore, the need to find the best way in estimating missing values is very important so that the data analysed is ensured of high quality. In this research, three types of mean imputation techniques that are mean, mean above and mean above below methods were used to replace the missing values. Annual hourly monitoring data for PM₁₀ were used to generate missing values. Four randomly simulated missing data were evaluated in order to test the efficiency of the methods used. They are 5%, 10%, 15%, 25% and 40%. Three types of performance indicators that are mean absolute error (MAE), root mean square error (RMSE) and coefficient of determination (R²) were calculated to describe the goodness of fit for all the method. From all the method applied, it was found that mean above below method is the best method for estimating data for all percentages of simulated missing values.

Abstract: This document analyzes the wireless ad hoc networks used in vehicle communication. Using the NS2 software, the typical ad hoc on-demand distance vector routing (AODV) and destination-sequenced distance-vector (DSDV) routing protocol are simulated respectively with 25 mobile nodes and 11 mobile nodes. By reasoning on the simulation data, many performance indicators including the routing protocol throughput, jitter, packet loss rate and end-to-end delay performance are compared and analyzed. Final we have come to an important conclusion that AODV is better than DSDV protocol on a number of performance indicators.

Abstract: The processing of three-dimensional structure and servo feed systems for micro-EDM have strict requirements.The two positioning method is used to solve the contradiction between the large stroke and high precision, Coarse and fine action units matched to achieve the precision positioning requirements. A combined device with piezoelectric ceramic and step motor has been employed as drive and use the linear rolling guide As the transmission in this study,which has strong control function ，great flexibility, high positioning accuracy and repeatability. The basic performance of the platform met the needs of micro-EDM control.

Abstract: Wind energy has been most prevalently utilized to generate electric power due to non pollution to the environment and the conservation of fossil fuel resources. The energy generated from wind turbine depends on the wind site characteristics and the wind turbine parameters. So, the choice of certain wind turbine for specific site is very important in terms of price of electric energy generated from wind energy system. Therefore, optimal choice of wind turbine is one of the most crucial issues in the design of wind energy system, which can utilize wind energy as efficiently as possible and achieve the best economic benefits. So this paper introduces a new and simple mathematic formulation for the wind turbine-site matching problem, based on wind speed characteristics of any site and the power curve parameters of any wind turbine. Wind speed at any site is characterized by the scale parameter (c) and the shape parameter (k) of the Weibull distribution function. The power curve parameters of any wind turbine are characterized by the cut-in, rated, and furling speeds and the rated power. The new formulation method is derived based on a generic formulation for the product of the Capacity Factor (CF) and Normalized Power (P_N). Three case studies are also presented to demonstrate the effectiveness of the proposed method to choose between a group of wind sites and a list of commercial wind turbines.