Prime-based method for interactive mining of frequent patterns

Over the past decade, an increasing number of efficient mining algorithms have been proposed to mine the frequent patterns by satisfying a user specified threshold called minimum support (minsup). However, determining an appropriate value for minsup to find proper frequent patterns in different applications is extremely difficult. Since rerunning the mining algorithms from scratch can be very time consuming, researchers have introduced interactive mining to find proper patterns by using the current mining model with various minsup. Thus far, a few efficient interactive mining algorithms have been proposed. However, their runtime do not fulfill the need of short runtime in real time applications especially where data is sparse and proper frequent patterns are mined with very low values of minsup. As response to the above-mentioned challenges, this study is devoted towards developing an interactive mining method based on prime number and its special characteristic “uniqueness” by which the content of the relevant data is transformed into a compact layout. At first, a general architecture for interactive mining is proposed consisting of two isolated components: mining model and mining process. Then, the proposed method is developed based on the architecture such that the mining model is constructed once, and it can be frequently mined by various minsup. In the mining model construction, the content of relevant data is captured by a novel tree structure called PC-tree with one database scan and mining materials are consequently formed. The PC-tree is a well-organized tree structure, which is systematically built based on descendant making introduced in this study. Moreover, this study introduces a mining algorithm called PC-miner to mine the mining model frequently with various values of minsup. It grows an effective candidate head set introduced in this study starting from the longest candidate patterns by using the Apriori principle. Meanwhile, during the growing of the candidate head set in each round, the longest candidate patterns are used to find maximal frequent patterns from which the frequent patterns can be derived. Moreover, the PC-miner reduces the number of candidate patterns and comparisons by using several pruning techniques. A comprehensive experimental analysis is conducted by several experiments and scenarios to evaluate the correctness and effectiveness of the proposed method especially for interactive mining. The experimental results verify that the proposed method constructs the mining model independent of minsup once and this enable the model to be frequently mined. The results also show that the proposed method mines frequent patterns correctly and efficiently. Moreover, the results verify that the proposed method speeds up interactive mining of frequent patterns over both sparse and dense datasets with more scalable total runtime for very low values of minsup over sparse datasets as compared to results from the previous work

Cold-start Problem in Collaborative Recommender Systems: Efficient Methods Based on Ask-to-rate Technique

To develop a recommender system, the collaborative filtering is the best known approach, which considers the ratings of users who have similar rating profiles or rating patterns. Consistently, it is able to compute the similarity of users when there are enough ratings expressed by users. Therefore, a major challenge of the collaborative filtering approach can be how to make recommendations for a new user, that is called cold-start user problem. To solve this problem, there have been proposed a few efficient methods based on ask-to-rate technique in which the profile of a new user is made by integrating information gained from a quick interview. This paper is a review of these proposed methods and how to use the ask-to-rate technique. Consequently, they are categorized into non-adaptive and adaptive methods. Then, each category is analyzed and their methods are compared

A comprehensive study of effective parameters on the thermal performance of porous media micro combustor in thermo photovoltaic systems

Low thermal performance is one of the biggest challenges of using micro combustor in Thermo-photovoltaic (TPV) system. In this study, a novel micro-combustor with porous media was designed and installed to enhance energy and exergy performance. Furthermore, the effects of several effective parameters including different porous media materials, length, porosity coefficient, and inlet mass flow on energy efficiency, exergy, entropy generation, wall temperature and its uniformity were studied. A comprehensive CFD model for using porous media in the micro-combustor of TPV systems was proposed. Results showed utilizing porous media significantly improve the exergy efficiency and energy output of TPV system. Therefore, using a 6 mm long porous media increased the average wall temperature by 111 K compared to the case without porous media. Additionally, the uniformity coefficient of the wall temperature decreased by 80.05 %, from 4.58 % to 0.89 %. This reduction increased the temperature uniformity of the outer wall of the micro-combustor with porous media compared to the case without a media, increasing the system’s lifetime. Moreover, the 6 mm-long porous media enhanced radiation efficiency and exergy efficiency by 37 % and 79.7 %, respectively, compared to the conventional micro combustor. The total energy conversion efficiency from the fuel chemical energy to electric power increased from 8.9 % to 12.32 %.<br/

A comprehensive study of effective parameters on the thermal performance of porous media micro combustor in thermo photovoltaic systems

Low thermal performance is one of the biggest challenges of using micro combustor in Thermo-photovoltaic (TPV) system. In this study, a novel micro-combustor with porous media was designed and installed to enhance energy and exergy performance. Furthermore, the effects of several effective parameters including different porous media materials, length, porosity coefficient, and inlet mass flow on energy efficiency, exergy, entropy generation, wall temperature and its uniformity were studied. A comprehensive CFD model for using porous media in the micro-combustor of TPV systems was proposed. Results showed utilizing porous media significantly improve the exergy efficiency and energy output of TPV system. Therefore, using a 6 mm long porous media increased the average wall temperature by 111 K compared to the case without porous media. Additionally, the uniformity coefficient of the wall temperature decreased by 80.05 %, from 4.58 % to 0.89 %. This reduction increased the temperature uniformity of the outer wall of the micro-combustor with porous media compared to the case without a media, increasing the system’s lifetime. Moreover, the 6 mm-long porous media enhanced radiation efficiency and exergy efficiency by 37 % and 79.7 %, respectively, compared to the conventional micro combustor. The total energy conversion efficiency from the fuel chemical energy to electric power increased from 8.9 % to 12.32 %.<br/

A numerical method for frequent pattern mining

Frequent pattern mining is one of the active research themes in data mining. It plays an important role in all data mining tasks such as clustering, classification, prediction, and association analysis. Identifying all frequent patterns is the most time consuming process due to a massive number of patterns generated. A reasonable solution is identifying maximal frequent patterns which form the smallest representative set of patterns to generate all frequent patterns. In this paper, an efficient numerical method for mining frequent patterns is proposed. This method is based on prime number characteristics to generate all frequent patterns by using maximal frequent ones. There are two new properties introduced in this method; a novel tree structure called PC_Tree and PC_Miner algorithm. The PC_Tree is a simple tree structure but yet capable to capture the whole of transactions information with an efficient data transformation technique that utilizes the prime number theory. The PC_Miner algorithm traverses the PC_Tree by using an efficient pruning technique. The experimental results verify the compactness and the efficiency of mining shown by the proposed method

High power Nd:YVO-KGW conical refraction laser

We have demonstrated the highest conical refraction (CR) laser output power to date by placing a CR crystal inside of a diode-pumped Nd:YVO laser cavity. The CR crystal did not have a significant influence on laser output power as well as efficiency. The CR laser produced the maximum output power of 3.68 W with the slope efficiency of 42 % and opticalto- optical efficiency of 34 %. Therefore, this approach could be an attractive pathway for further power scaling of the CR lasers

Hybrid of System Dynamics- Agent Based Analysis of Mobile Operators Revenue The Case: Digital Service Entry of MCCI Company

With the tremendous progress in communications in the world, the transformation andbehavior of mobile operators and their digitalization, which in the past were onlyservice providers, as well as the creation of different experiences for customers, isinevitable.The purpose of this study is to create a hybrid simulation of systemdynamics and agent based model in order to analyze the revenue of the first operator inthe country to enter the field of digital platform and development of nativeapplications. Using the model proposed, first operators need to enter the digital areaand produce native applications was expressed. Then, the factors that affect the mobileecosystem which, affect the production of applications and the development ofrequired platforms were described. By utilizing hybrid simulation of system dynamicsand agent based modeling, the income of mobile operator in entering and not enteringthe digital arena and producing native applications were examined. The results showthat with the entry of the operator into the field of production of native applicationsand the adoption of digital approach, consumers tended to use more data services, butdue to different tariffs for data and voice, the operator's income up to 2 Next years willnot change much