Optimization of a multi-response dynamic system aims at finding out a setting combination of input controllable factors that would result in optimum values for all response variables at all signal levels. In real life situation, often the multiple responses are found to be correlated. The main advantage of PCA-based approaches is that it takes into account the correlation among the multiple responses. Two PCA-based approaches that are commonly used for optimization of multiple responses in dynamic system are PCA-based technique for order preference by similarity to ideal solution (TOPSIS) and PCA-based multiple criteria evaluation of the grey relational model (MCE-GRM). This paper presents a new PCA-based approach, called PCA-based utility theory (UT) approach, for optimization of multiple dynamic responses and compares its optimization performance with other existing PCA-based approaches. The results show that the proposed PCA-based UT method is superior to the other PCA-based approaches.

This paper deals with the problem of grouping a set of objects into clusters. The objective is to minimize the sum of squared distances between objects and centroids. This problem is important because of its applications in different areas. In prior literature on this problem, attributes of objects have often been assumed to be crisp numbers. However, since in many realistic situations object attributes may be vague and should better be represented by fuzzy numbers, we are interested in the generalization of the minimum sum-of-squares clustering problem with the attributes being fuzzy numbers. Specifically, we consider the case where an object attribute is a triangular fuzzy number. The problem is first formulated as a fuzzy nonlinear binary integer programming problem based on a newly proposed dissimilarity measure, and then solved by developing and demonstrating a problem-specific ant colony optimization algorithm. The proposed algorithm is evaluated by computational experiments.

In this paper, we explored an economic production quantity model (EPQ) model for finite production rate and deteriorating items with time-dependent trapezoidal demand. The objective of the model under study is to determine the optimal production run-time as well as the number of production cycle in order to maximize the profit. Numerical example is also given to illustrate the model and sensitivity analyses regarding various parameters are performed to study their effects on the optimal policy.

This paper studies a three-level supply chain with one retailer, one distributer and one manufacturer under disruption. First, we show that profit sharing and return policy contracts established between members can coordinate this supply chain. Then, we investigate the effect of demand disruption in supply chain and we illustrate the possibility of breaking the initial desirable coordination. We consider two possible scenarios for the demand disruption separately; afterwards we define the revised coordinator parameters to respond to their effect in supply chain. Numerical examples for validation and evaluation of our model are also elaborated.

Trade credit is the most succeeding economic phenomenon which is used by the supplier for encouraging the retailers to buy more quantity. In this article, a mathematical model with stock dependent demand and deterioration is developed to investigate the retailer’s optimal inventory policy under the scheme of permissible delay in payment. It is assumed that defective items are produced during the production process and delay period is progressive. The objective is to minimize the total average cost of the system. To exemplify hypothesis of the proposed model numerical examples and sensitivity analysis are provided. Finally, the convexities of the cost functions and the effects of changing parameters are represented through the graphs.

Inventories are the materials stored either waiting for processing or experiencing processing and in some cases for future delivery. Inventories are treated both as blessings and evil. As they are like money placed in a drawer, assets tied up in investments, incurring costs for the care of the stored material and also subject to spoilage and obsolescence there have been a spate of programs developed by industries, all aimed at reducing inventory levels and increasing efficiency on the shop floor. Nevertheless, they do have positive purposes such as stable source of input required for production, less replenishment and may reduce ordering costs because of economies of scale. Finished goods inventories provide for better customer service. So formulating a suitable inventory model is one of the major concerns for an industry. Again considering reliability of any process is an important trend in the current research activities. Inventory models could be both deterministic and probabilistic and both of which must account for the reliability of the associated production process. This paper discusses the major works in the field of inventory modeling driven by reliability considerations, which ranges from the very beginning to latest works just published.

For many centuries, knowledge has been acting as the backbone of the progress of mankind but very recently it has been supplemented with the concept of management. Yet, the term knowledge management (KM) is being coined very recently and it has gained very huge popularity. Today, organizations have recognized the importance of knowledge management and are continuously working with it. The research paper is dedicated to different aspects of knowledge management and focuses on different views of the researchers on knowledge, knowledge management, KM processes, objectives, benefits, myths and errors.

This paper presents a survey on relationship between social capital and knowledge management for knowledge based organizations. This research is of descriptive-correlation one and the sample includes 100 faculty members of non-governmental institutes of Babol city. The instrument was questionnaire and the analysis performed using SPSS17 and Lisrel 8.8 software. Pearson correlation test, multiple regression analysis route analysis, and structural equations modeling were used as statistical tests. The research showed that social capital had direct and significant effect on knowledge management in 99% confidence interval. Among the dimensions of social capital, trust and social norms with knowledge application; trust with knowledge acquisition; trust and social norms with knowledge transfer; trust and networks association with knowledge creation; and trust, social norms and networks association with knowledge record had significant and positive effects in 95% confidence interval. Social capital was effective on knowledge management and knowledge based organizations could promote knowledge creation, acquisition, record, application and transfer process by improving social capitals.

The World Wide Web is a great source of information, which is nowadays being widely used due to the availability of useful information changing, dynamically. However, the large number of webpages often confuses many users and it is hard for them to find information on their interests. Therefore, it is necessary to provide a system capable of guiding users towards their desired choices and services. Recommender systems search among a large collection of user interests and recommend those, which are likely to be favored the most by the user. Web usage mining was designed to function on web server records, which are included in user search results. Therefore, recommender servers use the web usage mining technique to predict users’ browsing patterns and recommend those patterns in the form of a suggestion list. In this article, a recommender system based on web usage mining phases (online and offline) was proposed. In the offline phase, the first step is to analyze user access records to identify user sessions. Next, user profiles are built using data from server records based on the frequency of access to pages, the time spent by the user on each page and the date of page view. Date is of importance since it is more possible for users to request new pages more than old ones and old pages are less probable to be viewed, as users mostly look for new information. Following the creation of user profiles, users are categorized in clusters using the Fuzzy C-means clustering algorithm and S(c) criterion based on their similarities. In the online phase, a neural network is offered to identify the suggested model while online suggestions are generated using the suggestion module for the active user. Search engines analyze suggestion lists based on rate of user interest in pages and page rank and finally suggest appropriate pages to the active user. Experiments show that the proposed method of predicting user recent requested pages has more accuracy and cover than other methods.

Network coding (NC) is an approach for increasing the throughput of communication networks. NC has been derived from the idea of combining packets and forwarding them to achieve higher throughputs. From the very beginning, NC has attracted the attentions of scholars since they could improve the throughput of wired networks. Previous works have focused on the improvement of network throughput. Some methods add artificial delay to send packets. The methods are used in order to gain coding time and to increase throughput but they could not be used in immediate applications. However, early packets dispatch or adding delay to packets, for increasing coding time, can influence on the jitter of sent data. On the other hand, jitter is an important parameter in determining multimedia broadcasting time. Unlike previous methods, this paper provides a jitter-based coding algorithm using Jacobsen method. In the proposed method, the selection priority is based on packets jitter so that a packet with the minimum jitter is considered as the first priority for coding. Related computations are performed through Jacobson algorithm. According to simulation results, selecting a proper coding pattern for jitter can improve jitter by 30% while the throughput of this method shows no considerable change compared with that of available methods.