Showing 373 results for It
Fiseha Mekonnen Guangul, Girma Tadesse Chala, Subhash Chandra,
Volume 0, Issue 0 (10-2025)
Abstract
Strategic investment decisions across multiple projects require a systematic assessment of extensive quantitative and qualitative data, especially under conditions of resource constraints and uncertainty. Traditional single-project appraisal methods often fail to identify optimal portfolios aligned with organizational goals. This study presents a hybrid project portfolio selection framework integrating the Analytic Hierarchy Process (AHP), Simple Multi-Attribute Rating Technique (SMART), and 0–1 Integer Linear Programming (ILP) to enhance decision-making clarity and robustness. The framework employs a hierarchical structure, utilizing a comprehensive set of technical, commercial, socio-economic, financial, investment, and institutional criteria. AHP establishes consistent relative weights from expert judgments, while SMART scores candidate projects, generating aggregated scores that inform an ILP optimization model aimed at maximizing portfolio utility while adhering to budget constraints, mandatory project conditions, and interdependencies. Validation is performed using real data from an Endowment Corporate Office in Ethiopia, accounting for ongoing and prospective projects under varying demand scenarios. Scenario and sensitivity analyses reveal how variations in demand and criterion weights affect project rankings and portfolio composition, alongside an assessment of portfolio risk via variance and standard deviation. The hybrid AHP–SMART–ILP approach effectively considers both tangible and intangible objectives, achieving stable portfolios that address investment complexities and interdependencies.
Hamdi Ridha,
Volume 0, Issue 0 (10-2025)
Abstract
This paper proposes an explainable artificial intelligence (XAI)–based framework for automating dye recipe formulation in industrial textile manufacturing, with a focus on yarn rope dyeing for denim production. A deep learning multi-output regression model is developed to predict the resulting yarn shade components (L_cable, a_cable, b_cable) from heterogeneous industrial inputs, including customer-defined fabric shade targets, cotton fiber characteristics, and washing recipe parameters. To ensure transparency and industrial interpretability, Shapley Additive Explanations (SHAP) are integrated to provide global and output-specific explanations of the model’s predictions. The analysis reveals the dominant influence of cotton fiber properties, such as tenacity, micronaire, and fiber uniformity, alongside key controllable process parameters, including neutralization time, cellulose treatment duration, and detergent temperature. The proposed framework enables a clear distinction between raw-material-driven variability and process-adjustable levers, transforming the predictive model into an interpretable decision-support tool. The approach is validated using real industrial data from a Tunisian denim manufacturer and is readily transferable to similar textile dyeing and finishing processes.
Kaviyarasu Velappan, Nagarajan Arumugam,
Volume 0, Issue 0 (10-2025)
Abstract
The quality of pharmaceutical devices determines an entity's effectiveness in fulfilling its intended functions for patients. Statistical quality control entails the utilization of statistical methodologies to oversee and enhance the quality of processes and products. In the realm of the pharmaceutical industry, Reliability Acceptance Sampling Plans (RASP) entail inspecting a sample of items to ascertain whether the entire batch adheres to prescribed quality benchmarks, thereby curbing inspection expenses while upholding quality assurance of medical devices. The special Type of Double Sampling (STDS) plan constitutes a subset of reliability acceptance sampling plans that employ dual sampling stages to ascertain the batch acceptance or rejection of products or materials. This article develops a new methodology by employing the Special Type of Double Sampling plan under Exponential–Poisson (EP) distribution for the mean life when the product life test is truncated at a specified time.t0 ’. The minimum sample size ‘n’ required to guarantee the attainment of the designated mean life ‘β0 ’ within a predetermined consumer's risk. The Operational Characteristic (OC) function values are acquired based on varying tiers of quality and the minimum mean ratio of the real mean lifetime.β ’ to the designated mean lifetime ‘β0 ’ under the designated producer's risk are developed. Moreover, to enhance the comprehension of the proposed methodology, a numerical illustration accompanied by a real-world scenario that is applicable to the pharmaceutical industry is presented.
Aizi Mouna, Bouyaya Linda, Bouguern Siham,
Volume 0, Issue 0 (10-2025)
Abstract
This study applies a Genetic Algorithm (GA) to optimize the Vehicle Routing Problem with Time Windows (VRPTW) for NAFTAL, Algeria’s national fuel distribution company. The model minimizes both fleet size and total travel distance while achieving high compliance (99.3%) with customer time constraints. Using operational data from the Constantine regional network one depot serving 148 service stations (149 nodes in total ), the GA achieved optimal solutions deploying 94 vehicles covering 15,415.63 km. Results demonstrated exceptional convergence stability (σ = 0.00 across 40 runs) and high computational efficiency (under 60 seconds per optimization run). Sensitivity analyses confirmed the robustness of the calibrated configuration, highlighting its reliability and scalability for real-world logistics. The proposed framework provides NAFTAL with a cost-effective, consistent, and practical decision-support tool for optimizing fuel-delivery operations. Future research will focus on integrating machine learning for demand prediction, extending the model to multi-product and heterogeneous-fleet routing, and enabling adaptive real-time optimization to support smart and sustainable logistics.
Huki Chandra, Ilma Mufidah, Moch. Wibisono, Dhimas Nur, Raya Fahreza,
Volume 0, Issue 0 (10-2025)
Abstract
Constructions have considerable revenue and stakeholder accountability implications. It is the aim of this research to identify and assess risks so as to apply the appropriate controls for an Indonesian construction project. Observation, interviewing, and staff meetings were employed in this research. Risk analysis was conducted by a safety practitioner and validated with 12 construction workers. Methods like Fuzzy Logic (FMEA and AHP), PLS-SEM, Kruskal-Wallis, and cluster analysis were used to provide precise scoring and classification. Fuzzy Logic accommodated the uncertainty of risks, and Fuzzy-AHP ranked the risks with criteria of injury, asset loss, reputation, and environment. It defines two medium-risk and four high-risk activities, with the highest risk being Activity 2 (wall painting) due to being at height. Job Safety Analysis provides particular mitigation in detail. The RPN score for wall painting was 526, with a Mean Squared Error of 507 and an overall coefficient of variation of 6%, showing high consensus. This integrated methodology reduces bias, maintains uncertainty, and provides tailored safety recommendations, a new approach not implemented in past research.
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.
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.
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.
M.r. Alirezaee, S.a Mir-Hassani,
Volume 17, Issue 4 (11-2006)
Abstract
In the evaluation of non-efficient units by Data Envelopment Analysis (DEA) referenced Decision Making Units (DMU’s) have an important role. Unfortunately DMU’s with extra ordinary output can lead to a monopoly in a reference set, the fact called abnormality due to the outliers' data. In this paper, we introduce a DEA model for evaluating DMU’s under this circumstance. The layer model can result in a ranking for DMU’s and obtain an improving strategy leading to a better layer.
M. Kargari, Z. Rezaee, H. Khademi Zare ,
Volume 18, Issue 3 (11-2007)
Abstract
Abstract : In this paper a meta-heuristic approach has been presented to solve lot-size determination problems in a complex multi-stage production planning problems with production capacity constraint. This type of problems has multiple products with sequential production processes which are manufactured in different periods to meet customer’s demand. By determining the decision variables, machinery production capacity and customer’s demand, an integer linear program with the objective function of minimization of total costs of set-up, inventory and production is achieved. In the first step, the original problem is decomposed to several sub-problems using a heuristic approach based on the limited resource Lagrange multiplier. Thus, each sub-problem can be solved using one of the easier methods. In the second step, through combining the genetic algorithm with one of the neighborhood search techniques, a new approach has been developed for the sub-problems. In the third step, to obtain a better result, resource leveling is performed for the smaller problems using a heuristic algorithm. Using this method, each product’s lot-size is determined through several steps. This paper’s propositions have been studied and verified through considerable empirical experiments.
P. Akhavan, M. Fathian, M. Jafari ,
Volume 18, Issue 3 (11-2007)
Abstract
Abstract: Nowadays knowledge is recognized as an important enabler for competitive advantages and many companies are beginning to establish knowledge management systems. Within the last few years many organizations tried to design a suitable knowledge management system and many of them were successful. This paper is to discover critical success factors (CSF) of knowledge management (KM) and their relationships in an effective way. A qualitative case study technique has been used in this paper for data collection and analysis. In this way, grounded theory (GT) research approach has been selected .The collected data are categorized and analyzed through specific stages of GT. A semantic network has been developed by categorized data showing the relationships between the extracted CSFs and finally a theory has been emerged. The semantic network and the emerged theory show the roadmap of success in KM area for the organizations.
A. Arefmanesh, M. Najafi, H. Abdi ,
Volume 18, Issue 4 (12-2007)
Abstract
Abstract : The meshless local Petrov-Galerkin method with unity as the weighting function has been applied to the solution of the Navier-Stokes and energy equations. The Navier-Stokes equations in terms of the stream function and vorticity formulation together with the energy equation are solved for a driven cavity flow for moderate Reynolds numbers using different point distributions. The L2-norm of the error as a function of the size of the control volumes is presented for different cases and the rate of convergence of the method is established. The results of this study show that the proposed method is applicable in solving a variety of non-isothermal fluid flow problems.
H. Ahmadian, S. Nazari , H. Jalali ,
Volume 18, Issue 4 (12-2007)
Abstract
Abstract: The governing equations of motion for a drill string considering coupling between axial, lateral and torsional vibrations are obtained using a Lagrangian approach. The result leads to a set of non-linear equations with time varying coefficients. A fully coupled model for axial, lateral, and torsional vibrations of drill strings is presented. The bit/formation interactions are assumed to be related to the following parameters: bit motion, effects of gyroscopic moments, contact with the borehole wall, axial excitation due to bit/formation interactions, and hydrodynamic damping due to the presence of drilling mud. Simulation results show that parametric resonance and whirling may occur simultaneously within the range of operating conditions of drilling. The contact force between collar and borehole wall is calculated and its behavior is investigated. The dynamic behavior is quite complicated and may become non-periodic, suggesting a chaotic behavior.
H. Golestanian ,
Volume 18, Issue 4 (12-2007)
Abstract
Abstract: This paper presents the results of experimental determination of fiber bed permeability variation with porosity. Flow measurement experiments were designed to measure fiber mat permeability for fiber beds with various fiber volume fractions. Woven fiberglass, chopped fiberglass, and carbon fiber mats were used as reinforcements. The effects of reinforcement type and porosity on fiber bed permeability were investigated. Fiber mat permeability of woven mats showed large degrees of anisotropy, whereas chopped fiberglass mats had isotropic permeability. In all cases perform permeability increased with fiber bed porosity. Fiber mat permeability of woven carbon was found to be about four times lower than that of woven fiberglass mats at the same porosity. This lower permeability results in longer injection time and higher manufacturing cost for composite parts made with carbon fiber mats. The results of this investigation could be employed in process/product optimization in Resin Transfer Molding (RTM) processes.
Mohsen Faizi, Farhang Mozaffar , Mehdi Khakzand,
Volume 18, Issue 6 (7-2007)
Abstract
Fatemeh Mehdizadeh Saradj,
Volume 18, Issue 6 (7-2007)
Abstract
When a specific building is examined and analysed for its architectural merits, it is the visible, superficial aspects, which are considered, for example: aesthetics, function, spatial relationships, and landscape. One of the most important invisible factors that should be considered in the design process is the safety of buildings against natural hazards, particularly against earthquakes. While the provision of earthquake resistance is accomplished through structural means, the architectural designs and decisions play a major role in determining the seismic performance of a building. In other words, the seismic design is a shared architectural and engineering responsibility, which stems from the physical relationship between architectural forms and structural systems. It is economic to incorporate earthquake resistance in the stage of design than to add it later in the structural calculation or strengthening after completion. In addition, a building with proper earthquake-proof design will be more effective against earthquakes than the one with complementary strengthening. This paper will demonstrate that evidence for this lies in many historical buildings, which have withstood earthquakes throughout the hundreds of years without having been reinforced with special material. The fact is that the master builder or Mimar (traditional architect) of historic buildings was simultaneously designing the architecture as well as choosing the suitable form, proportion, and material for the best structural performance.
Asghar Mohammad Moradi , Mahdi Akhtarkavan,
Volume 18, Issue 6 (7-2007)
Abstract
The present paper will investigate the specific elements of architectural design based on Islamic beliefs, by taking Iranian Architectural values and vernacular climate design methods into consideration. This research will assess the spirit of experimental elements, created by the inhabitants, according to recent scientific findings. The main concentration will be on the physical design of rural areas in hot, arid and sunny regions of Iran in order to have active and healthy environments and to emphasize on transferring all these sustainable values to the future.
R. Farnoosh, B. Zarpak ,
Volume 19, Issue 1 (3-2008)
Abstract
Abstract: Stochastic models such as mixture models, graphical models, Markov random fields and hidden Markov models have key role in probabilistic data analysis. In this paper, we used Gaussian mixture model to the pixels of an image. The parameters of the model were estimated by EM-algorithm.
In addition pixel labeling corresponded to each pixel of true image was made by Bayes rule. In fact, a new numerically method was introduced for finding the maximum a posterior estimation by using EM-algorithm and Gaussians mixture distribution. In this algorithm, we were made a sequence of priors, posteriors were made and then converged to a posterior probability that is called the reference posterior probability. Maximum a posterior estimated can determine by the reference posterior probability which can make labeled image. This labeled image shows our segmented image with reduced noises. We presented this method in several experiments.
R. Tavakkoli-Moghaddam, M. Aryanezhad, H. Kazemipoor , A. Salehipour ,
Volume 19, Issue 1 (3-2008)
Abstract
Abstract : A tandem automated guided vehicle (AGV) system deals with grouping workstations into some non-overlapping zones , and assigning exactly one AGV to each zone. This paper presents a new non-linear integer mathematical model to group n machines into N loops that minimizes both inter and intra-loop flows simultaneously. Due to computational difficulties of exact methods in solving our proposed model, a threshold accepting (TA) algorithm is proposed. To show its efficiency, a number of instances generated randomly are solved by this proposed TA and then compared with the LINGO solver package employing the branch-and-bound (B/B) method. The related computational results show that our proposed TA dominates the exact algorithm when the size of instances grows.
