A robust solution to resource-constraint project scheduling problem

This paper aims to propose a solution to the resource-constraint project scheduling problem (RCPSP). RCPSP is a significant scheduling problem in project management. Currently, there are insufficient studies dealing with the robustness of RCPSP. This paper improves the robustness of RCPSP and develops a Robust RCPSP, namely RRCSP. RRCSP is structured with relaxing a fundamental assumption that is 'the tasks start on time as planned'. Relaxing this assumption makes the model more realistic. The proposed solution minimizes the makespan while maximizing the robustness. Maximizing the robustness requires maximizing floating time of activities (it is NP hard). This creates more stability in the project finishing time. RCPSP stands as the root cause of many other problems such as multi-mode resourceconstrained project scheduling problems (MRCPSP), multi-skill resource-constrained project scheduling problem (MSRCPSP), or similar problems and hence proposing a solution to this problem contributes to pave a new line for future research in other mentioned areas. The applicability of the proposed model is examined through a numerical example

Rapid and high-density covalent immobilization of Rhizomucor miehei lipase using a multi component reaction: application in biodiesel production

Aldehyde-functionalized silica and silica nanoparticles (SBA-15) were prepared as a matrix system for enzyme immobilization. Immobilization of Rhizomucor miehei lipase (RML) on these supports was performed via a multicomponent reaction under extremely mild conditions (25 °C, pH 7). Investigation on the mechanism of this reaction confirmed the Ugi four-component immobilization approach. The loading capacity of the supports and specific activity of the immobilized derivatives were interestingly improved. The results revealed very rapid immobilization of 10 and 60 mg of RML on 1 g of aldehyde-functionalized silica and SBA-15 after 10 and 30 minutes, respectively. Leaching experiments were performed by incubation of the immobilized derivatives in 1 M NaCl solution. The lack of the free lipase in the solution confirmed the covalent nature of the linkage. The thermal stability and co-solvent stability of the derivatives in the presence of three polar organic solvents (1-propanol, 2-propanol and dioxane) were greatly improved compared to the soluble enzyme. Both the derivatives were also used to catalyze the transesterification of colza oil with methanol to produce fatty acid methyl esters (FAMEs). In the case of RML immobilized on SBA-15 (SBA-RML), the presence of 40% of tert-butanol (v/v) as solvent in the reaction medium largely improved the conversion yield.Mehdi Mohammadi, Maryam Ashjari, Shaghayegh Dezvarei, Maryam Yousefi, Mohadese Babakic and Javad Mohammadi

A trust-based bio-inspired approach for credit lending decisions

Credit scoring computation essentially involves taking into account various financial factors and the previous behavior of the credit requesting person. There is a strong degree of correlation between the compliance level and the credit score of a given entity. The concept of trust has been widely used and applied in the existing literature to determine the compliance level of an entity. However it has not been studied in the context of credit scoring literature. In order to address this shortcoming, in this paper we propose a six-step bio-inspired methodology for trust-based credit lending decisions by credit institutions. The proposed methodology makes use of an artificial neural network-based model to classify the (potential) customers into various categories. To show the applicability and superiority of the proposed algorithm, it is applied to a credit-card dataset obtained from the UCI repository

A granular computing-based approach to credit scoring modeling

The credit card industry has been growing rapidly and thus huge numbers of consumers' credit data are collected by the credit department of the banks. The credit scoring managers often evaluate the consumer's credit with intuitive experience. However, with the support of the credit classification models, the managers can accurately evaluate the applicants' credit score. In this study, a neurocomputing-based granular approach is proposed to model credit scoring. Granular computing is used to compute the size of training and testing groups. Artificial neural networks (ANN) and data envelopment analysis (DEA) are used to model credit lending decisions in the online and offline manner, respectively. Proposed method is composed of three distinct stages based on trust and credibility concept. Trust is introduced and modeled via ANN in online module. Also credibility is modeled via DEA in offline module in present study. This paper is a pioneer in examining the concept of granularity for selecting the optimum size of testing and training group in machine learning area. In addition, proposing flexible trust ranges comparing to the current constant ones will support the importance of customers with higher credit scores to financial markets. To show the applicability and superiority of the proposed algorithm, it is applied to a credit-card data set obtained from the UCI repository. © 2013 Elsevier B.V

Performance assessment and optimisation of a large information system by combined customer relationship management and resilience engineering: a mathematical programming approach

ISs and ITs play a critical role in large complex gas corporations. Many factors such as human, organisational and environmental factors affect IS in an organisation. Therefore, investigating ISs success is considered to be a complex problem. Also, because of the competitive business environment and the high amount of information flow in organisations, new issues like resilient ISs and successful customer relationship management (CRM) have emerged. A resilient IS will provide sustainable delivery of information to internal and external customers. This paper presents an integrated approach to enhance and optimise the performance of each component of a large IS based on CRM and resilience engineering (RE) in a gas company. The enhancement of the performance can help ISs to perform business tasks efficiently. The data are collected from standard questionnaires. It is then analysed by data envelopment analysis by selecting the optimal mathematical programming approach. The selected model is validated and verified by principle component analysis method. Finally, CRM and RE factors are identified as influential factors through sensitivity analysis for this particular case study. To the best of our knowledge, this is the first study for performance assessment and optimisation of large IS by combined RE and CRM

Carta a Marino

"Mi flor es efímera y sólo tiene cuatro espinas para defenderse contra el mundo. ¡Y yo la he dejado sola allí!

In vitro toxicity assay of cisplatin on mouse acute lymphoblastic leukaemia and spermatogonial stem cells

Summary: Testicular cancer is the most common cancer affecting men in reproductive age, and cisplatin is one of the major helpful chemotherapeutic agents for treatment of this cancer. In addition, exposure of testes cancer cells to cisplatin could potentially eliminate tumour cells from germ cells in patients. The aim of this study was to evaluate the effect of cisplatin on viability of mouse acute lymphoblastic leukaemia cell line (EL-4) and neonatal mouse spermatogonial cells in vitro. In this study, the isolated spermatogonial stem cells (SSC) and EL-4 were divided into six groups including control (received medium), sham (received DMSO in medium) and experimental groups which received different doses of cisplatin (0.5, 5, 10 and 15 μg ml-1). Cells viability was evaluated with MTT assay. The identity of the cultured cells was confirmed by the expression of specific markers. Our finding showed that viability of both SSC and EL-4 cells was reduced with the dose of 15 μg/ml when compared to the control group (P � 0.05). Also, the differences between the IC50 in doses 10 and 15 μg/ml at different time were significant (P � 0.05). The number of TUNEL-positive cells was increased, and the BAX and caspase-3 expressions were upregulated in EL4 cells for group that received an effective dose of cisplatin). In conclusion, despite the dramatic effects of cisplatin on both cells, spermatogonial stem cells could form colony in culture. © 2016 Blackwell Verlag GmbH