فهرست مقالات control limit

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  1 - Productivity Improvement of BOB T-shirt through Line Balancing Using Control Limit analysis and discrete event simulation (Case study: - MAA Garment and Textile Factory)
  aregawi yemane
  10.22094/joie.2020.561766.1545
  This study deals with line balancing of BOB T-shirt model with the help of control limit analysis and discrete event simulation of the assembly lines. In this study control limit analysis is used to measure the performance of the assembly line and used to show the bottl چکیده کامل

  This study deals with line balancing of BOB T-shirt model with the help of control limit analysis and discrete event simulation of the assembly lines. In this study control limit analysis is used to measure the performance of the assembly line and used to show the bottleneck operations of the assembly line and line balancing technique improves the productivity of the sewing line of the model. BOB T-shirt model has 16 main operations and each operation’s time is analyzed as standard minute value (SMV). The main bottleneck operations are analyzed using the control limit analysis and simulation modeling. Based on the SMV of each operation, those operations which are out of lower control limit and upper control limit is called us bottlenecks of the sewing lines of the garment section and the 1st bottleneck operation is tread trimming operation. When we apply control limit analysis and discrete event simulation technique for the line balancing; the daily output has been increased from 1032 pieces to 1289 pieces. And labor productivity and machine productivity are increased from 46.9 and 54.32 to 58.59 and 71.61 respectively. And then finally, the profit that the line generated also increased from 22704 to 28358birr. پرونده مقاله
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  2 - An ex ante control chart for project monitoring using earned duration management observations
  Seyed Taha Hossein Mortaji Siamak Noori Rassoul Noorossana Morteza Bagherpour
  In the past few years, there has been an increasing interest in developing project control systems. The primary purpose of such systems is to indicate whether the actual performance is consistent with the baseline and to produce a signal in the case of non-compliance. R چکیده کامل

  In the past few years, there has been an increasing interest in developing project control systems. The primary purpose of such systems is to indicate whether the actual performance is consistent with the baseline and to produce a signal in the case of non-compliance. Recently, researchers have shown an increased interest in monitoring project’s performance indicators, by plotting them on the Shewhart-type control charts over time. However, these control charts are fundamentally designed for processes and ignore project-specific dynamics, which can lead to weak results and misleading interpretations. By paying close attention to the project baseline schedule and using statistical foundations, this paper proposes a new ex ante control chart which discriminates between acceptable (as-planned) and non-acceptable (not-as-planned) variations of the project’s schedule performance. Such control chart enables project managers to set more realistic thresholds leading to a better decision making for taking corrective and/or preventive actions. For the sake of clarity, an illustrative example has been presented to show how the ex ante control chart is constructed in practice. Furthermore, an experimental investigation has been set up to analyze the performance of the proposed control chart. As expected, the results confirm that, when a project starts to deflect significantly from the project’s baseline schedule, the ex ante control chart shows a respectable ability to detect and report right signals while avoiding false alarms. پرونده مقاله
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  3 - A new adaptive exponential smoothing method for non-stationary time series with level shifts
  Mohammad Ali Saniee Monfared Razieh Ghandali Maryam Esmaeili
  Simple exponential smoothing (SES) methods are the most commonly used methods in forecasting and time series analysis. However, they are generally insensitive to non-stationary structural events such as level shifts, ramp shifts, and spikes or impulses. Similar to that چکیده کامل

  Simple exponential smoothing (SES) methods are the most commonly used methods in forecasting and time series analysis. However, they are generally insensitive to non-stationary structural events such as level shifts, ramp shifts, and spikes or impulses. Similar to that of outliers in stationary time series, these non-stationary events will lead to increased level of errors in the forecasting process. This paper generalizes the SES method into a new adaptive method called revised simple exponential smoothing (RSES), as an alternative method to recognize non-stationary level shifts in the time series. We show that the new method improves the accuracy of the forecasting process. This is done by controlling the number of observations and the smoothing parameter in an adaptive approach, and in accordance with the laws of statistical control limits and the Bayes rule of conditioning. We use a numerical example to show how the new RSES method outperforms its traditional counterpart, SES. پرونده مقاله