Using productivity concept to predict material demand

2021 ◽  
Vol 14 ◽  
Author(s):  
Hui-Hsin Huang
Keyword(s):  
Characteristic Function ◽  
Probability Function ◽  
Probability Distributions ◽  
Demand Forecasting ◽  
Model Development ◽  
General Function ◽  
Input Material ◽  
Proposed Model ◽  
The Impact

Background: The issue of material demands prediction has been researched in industrial study and materials/ manufacturing technology many years ago. The previous researches based on stochastic model to discuss the quantities prediction of material demand. Some of them focus on multi-suppliers with characteristic function. Some use the information of past ordering quantities and ordering recency time. In these previous models, there is less study to discuss the impact of cost on material demand forecasting. Thus, this paper considers the productivities concept to make cost balance when forecasting material demand. The different probability distributions are demonstrated to portray the input (material demand) and output(cost). Methods: A case study with its empirical data is released to derive the probability function of cost and estimate the parameters of the proposed model. Results: The proposed model can extend to different distributions depending on different kind of cost or different type of industries and is more widely application. Conclusion: To consider manufacture's productivity, this model can help manager to control their cost and make a balance when ordering their materials. The model development of cost release a general function which makes it possible to extend different distributions depending on different kind of cost or different type of industries.

Assessing design process in engineering consultancy firms using lean principles

SIMULATION ◽  
2012 ◽  
Vol 88 (12) ◽  
pp. 1522-1536 ◽  
Author(s):  
M Marzouk ◽  
I Bakry ◽  
M El-Said
Keyword(s):  
Design Process ◽  
Comprehensive Model ◽  
Output Analysis ◽  
Lean Principles ◽  
Proposed Model ◽  
Client Request ◽  
Using Data ◽  
Consultancy Firm ◽  
The Impact

The aim of this research is to provide a tool for assessing the impact of applying lean principles to the design process at construction consultancy firms. Through several interviews, a comprehensive model was built to simulate the design process, using data from a leading consultancy firm in Egypt. The model contains the main processes and activities that form different phases of the design process and depicts the interconnectivity of processes and activities needed to create a complete design package upon client request. The research describes how the five main lean principles are integrated in the model. A case study is considered to demonstrate the effect of using the proposed model on the design process and to illustrate how the design process performs differently when lean principles are introduced. Case study output analysis reveals 40% improvement in the lean process performance measured in terms of activity utilization rates.

A Combined Power Demand Forecasting Model with Variable Weight

2013 ◽  
Vol 392 ◽  
pp. 618-621
Author(s):  
Zhi Gang Wang ◽  
Qing Jie Zhou ◽  
Xing Hua Zhou
Keyword(s):  
Demand Forecasting ◽  
Development Trend ◽  
Forecasting Model ◽  
Power Demand ◽  
Proposed Model ◽  
Variable Weight ◽  
The Difference ◽  
Demand Forecasting Model ◽  
Analysis Models ◽  
The Impact

A combined power demand forecasting model with variable weight considering both of the impact of the macroeconomic situation and the internal development trend is proposed. The proposed model consists of regression analysis models and the trend extrapolation models. The variable weight is determined by the difference of the prediction results between the two kinds of models . Beijing's power demand forecasting illustrates the usefulness and reliability of the combined model.

Impact of Residential and Public Charging Stations of Electric Vehicles on Distribution System by Stochastic Simulation

2015 ◽  
Vol 1092-1093 ◽  
pp. 375-380
Author(s):  
Suthida Ruayariyasub ◽  
Sompon Sirisumrannukul ◽  
Suksan Wangsatitwong
Keyword(s):  
Monte Carlo ◽  
Electric Vehicles ◽  
Distribution System ◽  
Stochastic Approach ◽  
Local Distribution ◽  
Battery Charging ◽  
Proposed Model ◽  
Charging Stations ◽  
The Impact

This paper investigates the impact of electric vehicles battery charging on the distribution system load if electric vehicles (EVs) are widespread used on roads. Stochastic approach based on a Monte Carlo method is developed in this study to simulate EVs charging load in two cases: 1) normal charge service at home, and 2) quick charge service at public charging stations. To demonstrate the model, a 22-kV distribution system of Pattaya City operated by Provincial Electricity Authority of Thailand (PEA) is employed in the case study. The results indicate the capability of the proposed model to exhibit the impact of EVs charging load on the local distribution system.

scholarly journals Impact of Guideline Markings on Saturation Flow Rate at Signalized Intersections

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Zhengtao Qin ◽  
Jing Zhao ◽  
Shidong Liang ◽  
Jiao Yao
Keyword(s):  
Flow Rate ◽  
Signalized Intersections ◽  
Estimation Model ◽  
Left Turn ◽  
Proposed Model ◽  
Research Goal ◽  
Saturation Flow Rate ◽  
Saturation Flow ◽  
The Impact

Many intersections around the world are irregular crossings where the approach and exit lanes are offset or the two roads cross at oblique angles. These irregular intersections often confuse drivers and greatly affect operational efficiency. Although guideline markings are recommended in many design manuals and codes on traffic signs and markings to address these problems, the effectiveness and application conditions are ambiguous. The research goal was to analyze the impact of guideline markings on the saturation flow rate at signalized intersections. An adjustment estimation model was established based on field data collected at 33 intersections in Shanghai, China. The proposed model was validated using a before–after case study. The underlying reasons for the impact of intersection guideline markings on the saturation flow rate are discussed. The results reveal that the improvement in the saturation flow rate obtained from painting guide line markings is positively correlated with the number of traffic lanes, offset of through movement, and turning angle of left-turns. On average, improvements of 7.0% and 10.3% can be obtained for through and left-turn movements, respectively.

scholarly journals An optimization model to solve the resource constrained project scheduling problem RCPSP in new product development projects•

DYNA ◽  
2020 ◽  
Vol 87 (212) ◽  
pp. 179-188 ◽  
Author(s):  
Néstor Raúl Ortíz Pimiento ◽  
Francisco Javier Diaz Serna
Keyword(s):  
Product Development ◽  
New Product Development ◽  
Optimization Model ◽  
New Product ◽  
Development Projects ◽  
Analysis Process ◽  
Proposed Model ◽  
Project Scheduling Problem ◽  
The Impact

New product development projects (NPDP) face different risks that may affect the scheduling. In this article, the purpose was to develop an optimization model to solve the RCPSP in NPDP and obtain a robust baseline for the project. The proposed model includes three stages: the identification of the project’s risks, an estimation of activities’ duration, and the resolution of an integer linear program. Two versions of the model were designed and compared in order to select the best one. The first version uses a method to estimate the activities’ duration based on the expected value of the impact of the risks and the second version uses a method based on the judgmental risk analysis process. Finally, the two version of the model were applied to a case study and the best version of the model was identified using a robustness indicator that analyses the start times of the baselines generated.

Instantaneous Probability of Uncontrolled External Leakage During the Production Phase of a Subsea Well

2013 ◽  
Author(s):  
Andre L. R. Alves ◽  
Theodoro A. Netto
Keyword(s):  
Failure Rate ◽  
Failure Modes ◽  
Probability Distributions ◽  
Base Case ◽  
Component Reliability ◽  
Production Phase ◽  
Common Cause Failures ◽  
Closed Position ◽  
The Impact

This work develops a methodology for evaluating the uncontrolled external leakage probability of a subsea well during the production phase. Based on a barrier diagram, an algorithm for possible leak paths identification is proposed, considering different operation modes: gas lift operation, free flowing or well closed at the subsea Xmas Tree. Considering the equivalency between these paths and the minimum cut sets from a fault tree modeling, the uncontrolled external leakage probability is calculated using the upper bound approximation. The effect of common cause failures is considered for the failure mode fail-to-close-valve. The instantaneous availability function of each component is modeled to represent the maintenance strategy applied. Non repairable, repairable and periodically tested items are used. For the latter, a nomenclature to distinguish two subtypes is introduced: the PT-R and PT-NR models, respectively Periodically Tested Repairable, and Periodically Tested Non Repairable. Probability distributions parameters are roughly estimated in order to make a case study. The failure rate functions determined are used as input for the proposed model, regarding the following failure modes: fail-to-close, external-leakage, and internal-leakage at the closed position. The objective of this section is to adjust a Weibull distribution, eliminate the usual assumption of constant failure rate and account for eventual wear-out effects. Finally, instantaneous probability results and sensitivity analysis are demonstrated for a base case study. Parameters like time between tests, inspections, and component reliability are varied in order to identify the impact on the uncontrolled external leakage probability. Therefore, the main objective is to propose a model that could support decision making on the well integrity management system during the production phase of a subsea well. To make this possible, reliable input data should be further considered.

scholarly journals Impact of Wind Power Generation on System Operation and Costs

2014 ◽  
Vol 8 (1) ◽  
pp. 580-588
Author(s):  
Wang Fei ◽  
Pan Wenxia ◽  
Quan Rui
Keyword(s):  
Wind Power ◽  
Power Plants ◽  
Unit Commitment ◽  
Mixed Integer ◽  
System Operation ◽  
Spinning Reserve ◽  
Proposed Model ◽  
Integer Problem ◽  
The Impact

In this paper, a deterministic security-constrained unit commitment (SCUC) model is deployed in order to optimize generation output and allocation for spinning reserve considering different wind power dispatch modes. In this model, the scheduling of power plants takes into account a simultaneous clearing of power, reserve capacity requirement and CO2 emission and so on. Spinning reserve is modelled as an exogenous parameter which represents load uncertainty and wind power uncertainty. Special attention in the study is given to determine the impact of different dispatch modes with wind power and different levels of spinning reserve requirement on system operation and costs. The proposed model can be formulated as a mixed-integer problem (MIP) and solved in GAMS by using the CPLEX optimizer. The model is applied to a wind-fired intensive power system for three case studies. The results include the optimal spinning reserve and generator output of each generator, CO2 emission cost and cost of wind power for each case study. The results show that taking wind power as a control option can improves system operation and costs if wind generation and traditional sources generation are coordinated properly.

Characterization of the degradation process of lithium-ion batteries when discharged at different current rates

2018 ◽  
Vol 232 (8) ◽  
pp. 1075-1089 ◽  
Author(s):  
Aramis Perez ◽  
Vanessa Quintero ◽  
Francisco Jaramillo ◽  
Heraldo Rozas ◽  
Diego Jimenez ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Lithium Ion Battery ◽  
Lithium Ion ◽  
Degradation Processes ◽  
Proposed Model ◽  
Public Data ◽  
Battery Degradation ◽  
The Impact

The use of energy storage devices, such as lithium-ion batteries, has become popular in many different domains and applications. Hence, it is relatively easy to find literature associated with problems of battery state-of-charge estimation and energy autonomy prognostics. Despite this fact, the characterization of battery degradation processes is still a matter of ongoing research. Indeed, most battery degradation models solely consider operation under nominal (or strictly controlled) conditions, although actual operating profiles (including discharge current) may differ significantly from those. In this context, this article proposes a lithium-ion battery degradation model that incorporates the impact of arbitrary discharge currents. Also, the proposed model, initially calibrated through data reported for a specific lithium-ion battery type, can characterize degradation curves for other lithium-ion batteries. Two case studies have been carried out to validate the proposed model, initially calibrated by using data from a Sony battery. The first case study uses our own experimental data obtained for a Panasonic lithium-ion cell, which was cycled and degraded at high current rates. The second case study considers the analysis of two public data sets available at the Prognostics Center of Excellence of NASA Ames Research Center website, for batteries cycled using nominal and 2-C (twice the nominal) discharge currents. Results show that the proposed model can characterize degradation processes properly, even when cycles are subject to different discharge currents and for batteries not manufactured by Sony (whose data were used for the initial calibration).

scholarly journals Ground motion predictive modelling based on genetic algorithms

2011 ◽  
Vol 11 (10) ◽  
pp. 2781-2789 ◽  
Author(s):  
S. Yilmaz
Keyword(s):  
Genetic Algorithms ◽  
Epicentral Distance ◽  
Model Development ◽  
Predictive Modelling ◽  
South West ◽  
Proposed Model ◽  
Average Shear ◽  
Earthquake Research ◽  
Earthquake Research Institute

Abstract. This study aims to utilise genetic algorithms for the estimation of peak ground accelerations (PGA). A case study is carried out for the earthquake data from south-west Turkey. The input parameters used for the development of attenuation relationship are magnitude, depth of earthquake, epicentral distance, average shear wave velocity and slope height of the site. Earthquake database compiled by the Earthquake Research Institute of Turkey was used for model development. An important contribution to this study is the slope/hill data included into the dataset. Developed empirical model has a good correlation (R = 0.78 and 0.75 for the training and overall datasets) between measured and estimated PGA values. The proposed model is also compared with local empirical predictive models and its results are found to be reasonable. The slope-hill effect found to be an important parameter for the estimation of PGA.

scholarly journals Coupling of the AQUATOX and EFDC Models for Ecological Impact Assessment of Chemical Spill Scenarios in the Jeonju River, Korea

Biology ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 340
Author(s):  
Jaehoon Yeom ◽  
Injeong Kim ◽  
Minjeong Kim ◽  
Kyunghwa Cho ◽  
Sang Don Kim
Keyword(s):  
Ecological Model ◽  
Ecological Impact ◽  
Species Group ◽  
Top Predators ◽  
Proposed Model ◽  
Efdc Model ◽  
The Impact ◽  
Substantial Change ◽  
Accident Site

In this study, an ecological impact was assessed for the short-term leak scenario through the AQUATOX-EFDC model, which combines the proven ecological model AQUATOX with the hydrodynamic model EFDC. A case study of the coupled AQUATOX-EFDC model was conducted for 30–30,000 kg toluene leak scenarios in the Jeonju River in South Korea. A 21-day scenario simulation was conducted, and the impact of the toluene spill accident was evaluated by comparing the biomass between the control simulation and the perturbed simulation. As a result of the simulation, it was found that in the scenario in which 3000 kg of toluene was leaked for a day, a substantial change was expected in the range of 0–640 m from the accident site. Additionally, for a 30,000 kg leak, a substantial change was expected in the range of 0–2300 m from the accident site, and the greatest damage was observed for the fish species group, the top predators. As a result, the AQUATOX-EFDC simulation showed a significant ecological impact, and the proposed model will be helpful to understand the ecological impact and establish the management strategy for the ecological risk of the chemical spill.

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