Inventory lot sizing and supplier selection for multiple products, multiple suppliers, multiple periods with storage space using lingo program

This study focuses on inventory lot sizing for supplier selection of multiple products; suppliers and periods with storage space constraint. The objective is to develop mathematical model. Lingo software program is used as solution tool. The proposed problem is found as mix integer linear programming (MILP) which beneficial for decision making of choosing optimal supplier and product in right period of time with minimum overall inventory cost.

Feasibility model for freight train insertion in one way – train schedule

In 2014, 94% distribution in Indonesia used by truck mode. But in recent years, the train mode begun to be used as a distribution transport mode of replacement trucks. For shipments with a distance of 500-1500 km, rail mode is more suitable due to cheaper transportation costs and faster delivery times. But in Indonesia railway infrastructure is only used 56% of total capacity. Therefore the current logistical challenge is how to optimize the use of railways. This research tries to develop mathematical model for determining freight trains that avoid the ovetaking. The model developed is a train slot model that inserts a freight train between fixed trains. Because there is a lot of input schedules, it requires a long computation time. Therefore, this research also develops decision support tools using Visual Basic Application in Microsoft Excel. The result showed that minimum headway effect on the determination of additional freight trains and the optimum minimum headway is 6 minutes. With 6 minutes of minimum headway, the additional freight train are 15 trains. This additional train increase the carrying capacity of 900 TEUs / day. When compared with the initial condition, it means the addition of transport capacity is 21,43%

Optimization of Hot Press Forging Parameters in Direct Recycling of Aluminium Chip (AA 6061)

This study introduces a new approach of direct recycling using the hot press forging process that eliminates the two intermediate processes of cold-compact and pre-heating. This method leads to low energy consumption without intervening the metallurgical processes. In this study, the optimum of machined chips from high speed milling is recycled by hot press forging. The mechanical properties and surface integrity of the different chips were investigated. The performance of recycled aluminium AA 6061 chips in the mechanical and physical properties were compared with the original aluminium billet. Response surface methodology (RSM) was used to develop mathematical model of the effects on pre-compaction cycle, holding time and suitable pressure significant to the process. It is hoped that, utilization of primary metal could be fully utilized by direct recycling technique (hot press forging) introduced in this study and at the same time developing a sustainable manufacturing process technology for future needs.

Optimization of Laser Transmission Joining Process Parameters on Joint Strength of PET and 316 L Stainless Steel Joint Using Response Surface Methodology

The objective of the present work is to study the effects of laser power, joining speed, and stand-off distance on the joint strength of PET and 316 L stainless steel joint. The process parameters were optimized using response methodology for achieving good joint strength. The central composite design (CCD) has been utilized to plan the experiments and response surface methodology (RSM) is employed to develop mathematical model between laser transmission joining parameters and desired response (joint strength). From the ANOVA (analysis of variance), it was concluded that laser power is contributing more and it is followed by joining speed and stand-off distance. In the range of process parameters, the result shows that laser power increases and joint strength increases. Whereas joining speed increases, joint strength increases. The joint strength increases with the increase of the stand-off distance until it reaches the center value; the joint strength then starts to decrease with the increase of stand-off distance beyond the center limit. Optimum values of laser power, joining speed, and stand-off distance were found to be 18 watt, 100 mm/min, and 2 mm to get the maximum joint strength (predicted: 88.48 MPa). There was approximately 3.37% error in the experimental and modeled results of joint strength.

Operational Emission Reduction Capability of Regional Power System

Based on the current development status of China power system, this article aims to analyze factors that have influence on operations emission reduction capability of regional power system, and develop mathematical model for emission reduction capability measurement. The great potential emission reduction capability will be calculated by applying this model to Jilin Province.

Optimization of the nutrition for biodegradation of vinasse by Aspergillus oryzae using response surface methodology

Direct discharge of vinasse from the distillery industry causes resource wasting and environmental destruction due to its mass of organic components. Aspergillus oryzae CGMCC5992 is capable of degrading the organic substrates of wastewater. One-factor-at-a-time design was adopted to select the most important nutrients influencing the degradation of organic materials of vinasse. Box–Behnken Design (BBD) with Design-Expert (8.0.4) was used to develop mathematical model equations, study responses, and optimize concentrations of the key nutrients to improve the degradation efficiency. The optimized medium containing 0.3 g/L urea, 20.73 mg/L ZnSO4, and 19.79 mg/L vitamin B6 was supplied to 10-times diluted vinasse; under the optimal condition, a decrease of chemical oxygen demand (COD) from 4,635 to 323 mg/L in vinasse was achieved in 5 days. The reduction of vinasse COD after the optimization of nutrient condition in this study is more significant than those reported previously.

MODEL MATEMATIKA OPTIMASI UNTUK PERBAIKAN PROSES PENGGORENGAN VAKUM TERHADAP TEKSTUR KERIPIK BUAH

Hard and crunchy are specific characteristics of fried product prefered by consumer. To have texture of crunchy productbeing suitable with consumer taste, it is necessary to observ characteristic change of raw material and frying condition. Infrying process, the changes of hardness and crunchiness characteristics of food occur. These changes are predicted caused by free water vaporization and the decrease of starch content in food. The objective of this research is to develop mathematical model of hardness and crunchiness changes as the function of water and extract content degradation. Sample of the research is jack fruit fried in the temperature of 70–100° C, duration of 15–60 minutes, and pressure of 80–90 kPa. The parameters observed are hardness and crunchiness, water and starch content before and after frying. The result showed that hardness and crunciness change as the function of water vaporization and the decrease of starch content can be used to predict hardness and crunciness of product during vacuum frying.

Utilization of Numerical Techniques to Predict the Thermal Behavior of Wood Column Subjected to Fire. Part A: Using Finite Element Methods to Develop Mathematical Model for Wood Column

The mathematical model to predict the temperature history for wood column is needed in order to determine its fire resistance when exposed to fire. In this paper, an intelligent methodology called Finite Element Method (FEM) of performing analysis for the square and circular wood columns by virtually or artificially developing a temperature history mathematical model. Numerical simulation model has been developed for the wood column by using two-dimensional mathematical model. The two-dimensional mathematical model was developed by using Galerkin’s Weighted Residual technique. This model focuses on the regional material of the wood column for describing its thermal behavior. When the temperature history in a column and relevant materials properties are known, the strength of the column can be calculated at any time during fire. Therefore, the development of the temperature history mathematical model is a must before any further study to be carried out for the wood columns. The flow of convection will result in minimal increase in the rate of heat energy reaching the column core. The analysis shows that the temperature of the column increases with respect to the duration of exposure to fire.