Showing 682 results for Type of Study: Research
Dino Caesaron, Farell Ardani, Vidhea Nurhadi, Yusuf Yekti,
Volume 0, Issue 0 (10-2024)
Abstract
A typical definition of New Product Development is a series of actions that begins with the identification of a market opportunity and concludes with the creation, marketing, and delivery of a product. It is a knowledge-based process where constraints and needs are converted into a product description. The competition for businesses now centers on innovation and new products. Industries and investors are constantly looking for new upgrade methods and/or equipment to reduce costs and increase capability. One industry in Indonesia that has a tight competitive level is the ceramics industry with a growth rate of 10% per year. The main objective of this study was to create the design of specific machining sanitary Spare Parts production due to complexity of the design. In the proposed methodology, Quality Function Deployment is used to convert the subjective requirements from users into an objective technical response. Theory of Solving Problem Inventively is used to enhance the subpar design by reducing system conflicts and creating a balanced solution between two requirements. The implications of the integration of Quality Function Deployment and Theory of Solving Problem Inventively in this paper are a product design and concept of the specific machining for sanitary spare parts that have been adjusted to the needs of users.
Khatereh Rajinia, Mostafa Razmkhah,
Volume 0, Issue 0 (10-2024)
Abstract
A periodic maintenance policy through either an imperfect repair or replacement is proposed for a repairable system. It is assumed that the system is subject to an inverse Gaussian degradation process. The effect of imperfect repair is modelled through both arithmetic reduction of degradation and arithmetic reduction of age approaches. The degradation level of the system is measured after each imperfect repair in periodic time intervals. The system is replaced if its deterioration level exceeds a pre-determined technical threshold or at the nth inspection time, whichever occurs first. The main goal of the paper is to find the optimal value of n based on expected cost rate function. Some theoretical results are derived and then the optimal policy is obtained numerically. The effect of imperfect repair, the inspection time interval, the value of technical degradation threshold, and the costs of interest are all studied on the optimal policy.
Ahmad Aliyari Boroujeni, Ameneh Khadivar,
Volume 0, Issue 0 (10-2024)
Abstract
The Traveling Salesman Problem (TSP) is a well-known problem in optimization and graph theory, where finding the optimal solution has always been of significant interest. Optimal solutions to TSP can help reduce costs and increase efficiency across various fields. Heuristic algorithms are often employed to solve TSP, as they are more efficient than exact methods due to the complexity and large search space of the problem. In this study, meta-heuristic algorithms such as the Genetic Algorithm and the Teaching-Learning Based Optimization (TLBO) algorithm are used to solve the TSP. Additionally, a discrete mutation phase is introduced to the TLBO algorithm to enhance its performance in solving the TSP. The results indicate that, in testing two specific models of the TSP, the modified TLBO algorithm outperforms both the Genetic Algorithm and the standard TLBO algorithm in terms of convergence to the optimal solution and response time.
Tenaw Tegbar Tsega, Thoben Klaus-Dieter, Rao D.k. Nageswara, Bereket Haile Woldegiorgis,
Volume 0, Issue 0 (10-2024)
Abstract
So far, several models for measuring supply chain performance (SCP) have been developed. The supply chain operation reference (SCOR) model is regarded as the most crucial in the manufacturing business. However, none of the models, including the SCOR model, are comprehensive enough to measure the overall SCP of manufacturing firms. In practice, the existing models are only used in a few of the numerous steps necessary to calculate the overall SCP. Furthermore, the existing models lack fundamental elements that a model should include. The objective of this research is to develop a powerful SCP measurement using a systematic literature review (SLR). Accordingly, this research has proposed a complete supply chain operations measurement (C-SCOM) model. The proposed model consists of four major components: the application of the SCOR model, the application of the AHP method, a template that enables overall SCP calculation, and a direction for linking supply chain management practices (SCMPS) with gap analysis. By having these features, the model provides users with the ability to calculate the overall SCP, conduct gap analysis, carry out benchmarking, and link the gap analysis outputs to existing SCMPs, which the previous models lack. The validation using the fuzzy Delphi technique reveals that the proposed model is unique in its explicitness and will be user-friendly for real-world industrial applications. Finally, this study contributes to the body of knowledge by providing a comprehensive model that could help solve the real challenges that manufacturing firms face when measuring SCP.
Mehdi Ajalli, Narges Soleiman Ekhtiyari, Peyman Zandi,
Volume 0, Issue 0 (10-2024)
Abstract
This study aims to evaluate the traditional, lean and agility criteria that are effective in evaluating the performance of suppliers and ranking them with the combined approach Path Analysis (PA), SWARA (Stepwise Weight Assessment Ratio Analysis) and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) in Automation Industry. The research method is applied from the perspective of the objective and is descriptive-survey in terms of data collection. For this purpose, the sub-criteria were first extracted by reviewing the literature. Then, using PA approach, the effectiveness of these criteria in automation industry was investigated. The statistical population in this section includes 60 experts and managers of the industry, which due to the smal size, all members of the community were considered as a sample. The PA output showed that after evaluating twentycriteria, seventeen criteria were finally approved by the experts. Then, using the SWARA and the opinions of experts, the criteria importance and weight was calculated. The results showed that the criterion of "agility" was in the first place, "lean" was in the second place and "traditional" was in the last place. Then, considering the importance of ranking of lean and agile suppliers in the industry, using TOPSIS and based on the weight of the criteria, six suppliers were evaluated by experts. The results showed that the fourth supplier was ranked first. The first supplier was also ranked sixth. Finally, a sensitivity analysis of the ranking was conducted. Overall, the results show a high degree of stability of the rankings according to the method used. Thus, the model proposed in this study provides a suitable framework for evaluating industry suppliers based on key criteria of traditional, lean and agility.
Ahmad Mohammadpour Larimi, Babak Shirazi, Iraj Mahdavi,
Volume 0, Issue 0 (10-2024)
Abstract
location-inventory problem (LIP) is a significant issue in supply chain management (SCM), aiming to reduce and integrate the costs of inventory and location. Perishable-LIP (PLIP) includes products, particularly those with a short expiration date, also known as perishable items. This feature necessitates the supply chain to maintain high reliability and resilience to minimize costs faced with disruption risks. Implementing reliability and resilience in PLIP (R2-PLIP) requires methods such as lateral transshipment. These methods not only enhance the reliability and resiliency of the SC but also mitigate the risks associated with supply disruptions and demand fluctuations. Demand for perishable products is influenced by their expiration dates. By incorporating lateral transshipment, companies can ensure a more balanced inventory distribution. This study investigates the role of lateral transshipment in enhancing supply chain robustness. A multi-objective optimization model is developed, focusing on minimizing costs while maximizing resilience and service levels. The project aims to optimize the overall system efficiency. Additionally, the sensitivity analysis conducted in the research indicates that the shortage cost and the DC capacity each had the greatest variations in one of the objective functions. This research provides practical insights for designing resilient perishable supply chains.
Hendro Prassetiyo, Said Muhammad Baisa, Arif Imran, Sri Suci Yuniar, Rangga Try Anugrah,
Volume 0, Issue 0 (10-2024)
Abstract
This study focuses on optimizing vendor selection in laser cutting services through a comprehensive evaluation framework integrating the Vendor Performance Indicator (VPI) and the Fuzzy Analytical Network Process (F-ANP). The methodology quantifies vendor performance across five key criteria: quality, cost, delivery, flexibility, and responsiveness. The results indicate that product quality (39.7%) and cost efficiency (41.4%) are the most influential factors in vendor selection. Sensitivity analysis reveals that a 10% increase in quality consistency improves overall vendor ranking stability by 15%, while cost variations above 8% significantly affect final rankings. The study recommends implementing performance-based contracts, quality assurance protocols, and digital supply chain solutions to enhance vendor assessments. Collaborative partnerships with top-performing vendors can yield mutual benefits and foster sustainable practices, aligning with the company's resilience and operational excellence objectives.
Alemayehu Derege,
Volume 0, Issue 0 (10-2024)
Abstract
The booming of construction sector, including cement factories, has been great success, however, the price of cement has been quadrupled. Among others, critical shortage of cement is observed throughout the country regardless of the success, demanding a critical investigation into its supply chain, governance and regulatory system. Mixed, qualitative and quantitative approaches are applied to investigate the value chain, its administration and regulatory framework. SEM was used to index the level of cement supply distortions in the country. Samples are taken through referral technique from stratified target group across Ethiopian cement supply chain, starting from factory CEO to end-users, from purposively selected major factories. Multinomial logit model is used to analyze the determinant of cement supply distortion. The study found mis-management of regulation, high intervention with ineffective regulatory measure, opened up a room for bribery, favoritism, government interventionism and amplified the roles of intermediaries beyond the market requirement. Brokers are involved in about 85 percent of the country's total cement distribution. Besides, not only intermediaries but also the factories and their agents are contributing a lot in cement supply distortion. The supply chain distortion is observed in all market types, black, gray, and white respectively. The regulatory framework is ineffective and few regulatory bodies are fixed towards reactive measures. Majority of cement distribution is facilitated by brokers and factory agent. Hoarding and smuggling emerge as the most influential factors, with their increase being strongly and significantly linked to a rise in high and severe illegal cement distribution. Regulatory strength and administrative malpractice display complex patterns, indicating that having policies in place is not sufficient; effective enforcement is crucial. Strengthening regulatory, good governance and law enforcement system reduces the cement supply distortion while long run digitalization should be targeted along with supply side intervention.
Mehdi Abdollahi Kamran, Samira Afsharfar, Fatma Al Mawali, Reza Babazadeh, Marya Al Balushi,
Volume 0, Issue 0 (10-2024)
Abstract
One of the most critical concerns in supply chain management (SCM) is supplier selection, which significantly impacts an organization's efficiency and market agility. Balancing ordinal and basic criteria in supplier selection has become increasingly crucial in recent years within SCM. This research presents three multi-criteria decision-making (MCDM) methods including Fuzzy analytic hierarchy process (AHP) and Fuzzy technique for order preference by similarity to ideal solution (TOPSIS) methods to assess and select suppliers in oil and gas (O&G) industry. The critical criteria for supplier selection in the O&G sector have been reviewed in the literature and validated by experts actively working in the field. Initially, the Fuzzy AHP technique determines criterion weights and ranks suppliers. Subsequently, the Fuzzy TOPSIS approach is applied to rank prospective suppliers identified through objective evaluation. The findings show the capability of the utilized approaches in supplier selection procedure in O&G industry.
Weny Findiastuti, Fitri Agustina, Rullie Annisa, Ach Dafid, Iffan Maflahah, Ananda Rafli Siswanto,
Volume 0, Issue 0 (10-2024)
Abstract
Indonesia faces environmental challenges due to the increasing exploitation of natural resources and industrial emissions. This study aims to design an environmental impact mitigation strategy in the furniture industry using the Life Cycle Assessment (LCA) method, with a case study of UD Putra Bali. The analysis includes the Life Cycle Inventory (LCI), Life Cycle Impact Assessment (LCIA), and Life Cycle Interpretation to identify the greatest impacts and develop recommendations for improvement. The results of the study indicate that the life cycle of wooden door products produces an environmental impact of 13.1 kPt. The stage with the greatest impact is the finishing process, especially in the human toxicity water category of 11.3 kPt, due to thinner-based paint. In addition, the delivery of finished products contributes to the global warming category of 0.0539 kPt, which is caused by the use of vehicles with high emission specifications and inefficient delivery routes. Recommendations for improvement include the implementation of cleaner production, namely replacing thinner-based paint with more environmentally friendly water-based paint and optimizing delivery routes using the saving matrix nearest insert method to reduce the total distance traveled and transportation emissions. After the implementation of the mitigation strategy, the environmental impact of the finishing process decreased to 10.3 kPt, while the impact of the finished product delivery decreased to 0.0526 kPt. This study shows that the application of LCA can identify the main sources of environmental impacts and generate data-based improvement strategies. The implementation of this strategy is expected to enhance the sustainability of the furniture industry and reduce the production process's environmental footprint.
Davood Nazari Maryam Abadi, Mohammad Bagheri,
Volume 0, Issue 0 (10-2024)
Abstract
In this paper, an optimal Electrical Cam (Ecam) profile is obtained by identifying the best breakpoint positions for piecewise polynomials using the cubic spline interpolation method. To achieve a curve that best tracks the reference Ecam curve, the breakpoint positions are determined using particle swarm optimization with random inertia weight (RNW-PSO). The previous programmable logic controller (PLC) used in the sanding mechanism was the DELTA DVP40ES2, utilizing the Ecam capability of DELTA ASD-A2 servo motors. To implement the Ecam function independently of the servo motor type, it has been integrated into a PLC, specifically the SIEMENS SIMATIC CPU 1215C. The optimized Ecam curve is then applied to a computer numerical control (CNC) sanding machine. Practical results demonstrate the effectiveness of the proposed method, showing improved sanding quality and better compliance with the reference curve.
F.d. Javanroodi , K. M. Nikbin ,
Volume 17, Issue 3 (9-2006)
Abstract
There is an increasing need to assess the service life of components containing defect which operate at high temperature. This paper describes the current fracture mechanics concepts that are employed to predict cracking of engineering materials at high temperatures under static and cyclic loading. The relationship between these concepts and those of high temperature life assessment methods is also discussed. A model for predicting creep crack growth initiation and growth in terms of C* and the creep uniaxial ductility is presented and it is shown that this model gives good agreement with the experimental results. The effects of cyclic loading on crack growth behaviour are considered and fractography evidence is shown to back a simple cumulative damage concept when dealing with creep/fatigue interaction. Finally a discussion is presented which highlights the important aspect of life assessment methodology for high temperature plant.
H. Yarjiabadi, M. H. Shojaeefard, A.r. Noorpoor, H.yarjiabadi, , M. Habibian , A.r. Noorpoor ,
Volume 17, Issue 3 (9-2006)
Abstract
The hydrocyclone has a very important roll in industrial separation. The consideration of its behavior is very important for design. In this investigation, behavior of water flow and particles trajectory inside a hydrocyclone has been considered by means of numerical and experimental methods, and results have been compared together. To have a numerical simulation, a CFD software was used, and for modeling flow the RNG k – model applied. Finally, the effect of particle size on hydrocyclone performance has been studied. It was found that the grade efficiency and number of particle that exit from underflow of the hydrocyclone is increased when bigger particles is used.
A series of experiments has been carried out in a laboratory with a hydrocyclone. Comparison shows that, there is a good agreement between the CFD models and experimental result.
M. Haghpanahi, H. Pirali ,
Volume 17, Issue 3 (9-2006)
Abstract
Finite element analysis of a tubular T-joint subjected to various loading conditions including pure axial loading, pure in-plane bending (IPB) and different ratios of axial loading to in-plane bending loading has been carried out. This effort has been established to estimate magnitudes of the peak hot spot stresses (HSS) at the brace/chord intersection and to find the corresponding locations as well, since, in reality, offshore tubular structures are subjected to combined loading, and hence fatigue life of these structures is affected by combined loading. Therefore in this paper, at the first step, stress concentration factors (SCFs) for pure axial loading and in-plane bending loading are calculated using different parametric equations and finite element method (FEM). At the next step, the peak HSS distributions around the brace/chord intersection are presented and verified by the results obtained from the API RP2A Code procedure. Also the locations of the peak hot spot stresses which are the critical points in fatigue life assessment have been predicted.
M. M. Shokrieh, R. Rafiee ,
Volume 17, Issue 3 (9-2006)
Abstract
The main goal of this research is to extract the full mechanical properties of stitch biax and triax composite materials which are necessary for finite element analysis, based on limited available experimental data and without performing full static characterization tests. Utilized experimental data are limited to elastic modulus of two 0o and 45o directions. Using presented technique and aforementioned data, mechanical properties of unidirectional fabrics of biax and triax are obtained and consequently mechanical properties of biax and triax composites are calculated. Evaluation of the results proved proper performance of the technique in this research.
M.r. Modarres Razavi, S.h. Seyedein, P.b. Shahabi , S.h Seyedein,
Volume 17, Issue 3 (9-2006)
Abstract
In this paper hemodynamic wall parameters which play an important role to diagnose arterial disease were studied and compared for three different rheology models (Newtonian, Power law and Quemada). Also because of the pulsatile behavior of blood flow the results were obtained for three Womersley numbers which represent the frequencies of the applied pulses. Results show that Quemada model always located between Newtonian and Power law models however its behavior is closer to Power law model. Concerning this behavior and better agreement between Quemada and experimental blood viscosity, it can be expected that Quemada results are more realistic and accurate.
M. Nikian, , M. Naghashzadegan, S. K. Arya ,
Volume 17, Issue 3 (9-2006)
Abstract
The cylinder working fluid mean temperature, rate of heat fluxes to combustion chamber and temperature distribution on combustion chamber surface will be calculated in this research. By simulating thermodynamic cycle of engine, temperature distribution of combustion chamber will be calculated by the Crank-Nicolson method. An implicit finite difference method was used in this code. Special treatments for piston movement and a grid transformation for describing the realistic piston bowl shape were designed and utilized. The results were compared with a finite element method and were verified to be accurate for simplified test problems. In addition, the method was applied to realistic problems of heat transfer in an Isuzu Diesel engine, and gave good agreement with available experimental.
M. H. Shojaeefard, F. A. Boyaghchi , M. B. Ehghaghi ,
Volume 17, Issue 4 (11-2006)
Abstract
In this paper the centrifugal pump performances are tested when handling water and viscous oils as Newtonian fluids. Also, this paper shows a numerical simulation of the three-dimensional fluid flow inside a centrifugal pump. For these numerical simulations the SIMPLEC algorithm is used for solving governing equations of incompressible viscous/turbulent flows through the pump. The k-ε turbulence model is adopted to describe the turbulent flow process. These simulations have been made with a steady calculation using the multiple reference frames (MRF) technique to take into account the impeller- volute interaction. Numerical results are compared with the experimental characteristic curve for each viscous fluid. The data obtained allow the analysis of the main phenomena existent in this pump, such as: head, efficiency and power changes for different operating conditions. Also, the correction factors for oils are obtained from the experiment for part loading (PL), best efficiency point (BEP) and over loading (OL). These results are compared with proposed factors by American Hydraulic Institute (HIS) and Soviet :::union::: (USSR). The comparisons between the numerical and experimental results show good agreement.
Gh. Yari , M. D Jafari ,
Volume 17, Issue 4 (11-2006)
Abstract
Main result of this paper is to derive the exact analytical expressions of information and covariance matrix for multivariate Pareto, Burr and related distributions. These distributions arise as tractable parametric models in reliability, actuarial science, economics, finance and telecommunications. We showed that all the calculations can be obtained from one main moment multidimensional integral whose expression is obtained through some particular change of variables. Indeed, we consider that this calculus technique for that improper integral has its own importance.
A. Shidfar, Ali Zakeri,
Volume 17, Issue 4 (11-2006)
Abstract
This paper considers a linear one dimensional inverse heat conduction problem with non constant thermal diffusivity and two unknown terms in a heated bar with unit length. By using the WKB method, the heat flux at the end of boundary and initial temperature will be approximated, numerically. By choosing a suitable parameter in WKB method the ill-posedness of solution will be improved. Finally, a numerical example will be presented.
