Effect of online social networking on student academic performance

Online social networks (OSNs) have permeated all generations of Internet users, becoming a prominent communications tool, particularly in the student community. Thus, academic institutions and faculty are increasingly using social networking sites, such as Facebook and LinkedIn, to connect with current and potential students and to deliver instructional content. This has led to a rise in questions about the impact of OSN on academic performance and the possibility of using it as an effective teaching tool. To learn more about the impact on academic performance, we conducted a survey of business students at a large state university. Survey results were analyzed using structural equation modeling (SEM). The results revealed a statistically significant negative relationship between time spent by students on OSN and their academic performance. The time spent on OSN was found to be heavily influenced by the attention span of the students. Specifically, we determined that the higher the attention span, the lower is the time spent on OSN. Further, attention span was found to be highly correlated with characteristics that predict or influence student behavior, such as their perceptions about society’s view of social networking, their likes and dislikes of OSN, ease of use of OSN, etc.     

Benevolence trust: a key determinant of user continuance use of online social networks

Online social networking (OSN) has attracted increased attention and growing membership in recent years. In this paper, we propose and test an extended and unified theory of acceptance and use of technology (UTAUT) model, including the additional areas of satisfaction, credibility trust, and benevolence trust, using an empirical survey of 676 OSN users to examine the influence of these factors. The results of regression analysis showed that the four key constructs of UTAUT (social influence, performance expectancy, effort expectancy, and facilitating conditions), as well as satisfaction, credibility trust, and benevolence trust, are all direct determinants of user continuance use of OSN. By comparing the coefficients of regression analysis, the relative importance of each determinant was also demonstrated. Results further indicate that benevolence trust has a much more significant effect on user continuance use of OSN than any other factor. A discussion is offered on the implications of these findings for OSN managers with regard to marketing and operations.     

Two-stage DEA: An application to major Brazilian banks

Although banking has been widely studied using standard DEA (Data Envelopment Analysis) models and its variations, these models do not in fact account for the internal structure relative to measures characterizing banking operations performance. In this paper, efficiency in Brazilian banking is measured using a two-stage process. In the first stage, called cost efficiency, number of branches and employees are used to attain a certain level of administrative and personnel expenses per year. In the second stage, called productive efficiency, these expenses allow the consecution of two important net outputs: equity and permanent assets. The network-DEA centralized efficiency model is adopted here to optimize both stages simultaneously. Results indicate that Brazilian banks are heterogeneous, with some focusing on cost efficiency and others on productive efficiency. Furthermore, cost efficiency is explained by M&A and size, while productive efficiency is explained by M&A and public status. Policy implications for the Brazilian banking sector are also derived.     

面向服务组合的覆盖服务网络设计

提出了面向服务组合的覆盖服务网络(OSN)的设计方法。从节点放置和链路选择两方面考虑OSN的设计问题。给出了覆盖节点的放置模型,分别用不同算法求解。实验结果表明,Lagrangian松弛算法在寻优能力上高于贪婪算法和随机算法。用实验模拟了不同链路选择策略对OSN路由性能的影响,结果说明邻接连接拓扑结构的故障恢复率高、路由开销小,适合作为OSN的拓扑结构。     

Overlay网络上的覆盖节点的放置问题

Overlay服务网络是一种通用的服务框架,它利用覆盖网络技术来向用户提供各种各样的服务。该文在讨论Overlay服务网络的基础上,提出了覆盖节点放置的问题,对该问题进行了形式化,并提出了相应的算法,对算法进行了相应的仿真。     

Novel authentication procedures for preventing unauthorized access in social networks

Online Social Network (OSN) is the most widely used platform to communicate with one another. It is fast and cheap when compared to other modes of communication. However, Online Social Network profiles are being hacked often by employing various types of malicious attacks. Most of the times the attackers are successful in accessing the OSN account which illustrates that the present authentication mechanisms are not efficient enough. Once an online social network account is being hacked, it can be misused widely and the hacker makes the authorized user unable to login to the account by changing the login credentials. Security in OSN must be provided and it must prevent the attacks aimed by the attackers. However, to prevent unauthorized access in OSN a novel authentication procedure is needed and the novel authentication mechanism must abide the social network platform’s characteristics. This paper considers the attackers who aim to access the OSN account in an unauthorized manner and presents two novel authentication mechanisms to prevent the OSN platform. The proposed procedures make use of users’ chatting module statistics and relationship circle statistics to authenticate the users in Online Social Networks. This can be done by Multi kernel Fuzzy C-Means (MKFCM) Algorithm and Group Search Optimizer (GSO). These novel authentication procedures abide the OSN characteristics, as it makes use of Chatting and Relationship module.     

考虑环境因素的企业DEA 有效性分析

对企业投入-产出效率进行评价应将环境指标与经济指标相结合。利用数据包络分析（DEA）技术，建立了考虑环境因素的企业效率评价模型。在生产可能集不满足锥性的假设下，证明了新模型与原模型具有相同的有效性。并用一个算例进行说明。     

Measuring efficiency and productive performance of colleges at the university of Santo Tomas: a nonparametric approach

This paper estimates relative efficiency and productive performance of 13 colleges at the University of Santo Tomas (UST), using data envelopment analysis (DEA) – Malmquist indices and a multi‐stage model. DEA is a management evaluation tool that assists with identifying the most efficient and inefficient decision‐making units (DMUs) in the best practice frontier. Total factor productivity (TFP) is measured for a sample of 13 colleges at UST over the period 1998–2003. Empirical results show that the main contributing factor to TFP growth is efficiency change. That is, UST colleges are technically operating efficiently in the frontier technology; though there is a downward shift in the technological advancement. Our results further imply that with the use of output–input mix, UST colleges as a whole have recorded a higher level of technical efficiency than innovation. These new findings contribute significantly to the existing literature on efficiency and productive performance in the education sector.     

Decentralized model predictive control of a multi-evaporator air conditioning system

Temperature control of multiple zones with a multi-evaporator vapor compression system is a common problem in modern air conditioning. Due to the coupled system dynamics, standard decoupled controllers can interfere with each unit′s performance. This paper proposes an architecture that is decentralized and modular, avoiding competing controllers and the practical difficulty of implementing a centralized controller. A model predictive control (MPC) supervisor calculates evaporator cooling and pressure setpoints for each zone, balancing temperature regulation with energy efficiency; these setpoints are tracked by local level controllers, which rely upon MPC's ability to respect constraints in order to maintain safe, efficient operation.     

Measuring the technical efficiency of football legends: who were Real Madrid's all‐time most efficient players?

Many football players contribute to aggregate results throughout a football club's history. However, no scientific research has pinpointed the most technically efficient players in a football club's history considering their position on the field. The aim of this paper is to propose an output‐oriented nonincreasing returns to scale super‐efficiency data envelopment analysis (DEA) model in order to measure football players’ performance. The model is applied empirically to Real Madrid's best players (white legends) from the signing of Luis Molowny to Raúl González's departure. Results are also calculated and compared with the standard DEA in order to form the most efficient and super‐efficient historical squad of Real Madrid footballers.     

Beyond productivity—productivity and the three types of efficiencies of information technology industries

The purpose of this paper is to analyze productivity and efficiency of information technology industries of fourteen OECD countries. IT productivity has been studied for years and most papers have confirmed the IT productivity. Some even proved that IT productivity is far better than other factors. The impact of IT to the economy depends not only on the productivity but also on the size of IT production. Thus, to analyze productivity and efficiency of IT industries is important. They are the drive for the economic growth in the new economy. Although productivity has been analyzed and discussed in the information systems field for years, little research has been done in efficiency of IT.This paper analyzes the productivity and productive efficiency of fourteen OECD countries and compared them to each other. The models we used in this paper follow Kumbhakar's 1989 models [Rev. Econ. Stat. (1989) 595] and some other econometric models in other productive efficiency studies. By using these models, we were allowed to estimate three different types of (in)efficiencies—technical, allocative and scale, and the percentage loss due to the inefficiency.     

Abc classification with uncertain data. a fuzzy model vs. a probabilistic model

This study presents an alternative way of classifying the different productive items of a company. A fuzzy model for the magnitudes involved (demand and cost) is described. This model contrasts with the classic Pareto classification (ABC), which ranks productive items according to their importance in terms of frequency and costs. Whereas rankings obtained using the classical method are based on information about costs and demand over a period in the past, this new method allows new fuzzy information about the future to be included, thus allowing stricter control of the fuzzy ''A-items'' that result from this new classification. Rankings comparing a probabilistic model and its fuzzy counterpart are also provided in this study.     

Towards measuring the effectiveness of a facilities layout

Performance measurement models are essential to support various decision making problems that may arise during life cycle of a facilities layout. Available models are only suitable for early stages in the design phase of life cycle. However, measurement models have a great consequence in other phases also such as production planning, control and when modification to be incorporated due to the changes in market demand, which happens very often in today's global competition. In addition, the existing models have considered only material handling cost as the performance measurement factor. Nevertheless, the empty travel of material handling equipment, layout flexibility and area utilisation have a significant contribution towards the layout effectiveness. It is therefore necessary to have a measurement model to determine the facilities layout's effectiveness by considering all significant factors. A measurement model considering a set of three layout effectiveness factors—facilities layout flexibility (FLF), productive area utilisation (PAU) and closeness gap (CG)—is developed in our research. The proposed model will enable the decision-maker of a manufacturing enterprise to analyse a layout in three different aspects, based on which they can make decision towards productivity improvement. This paper mainly discusses about the measurement of the CG. The CG is developed with respect to the objective of bringing closer the highly interactive facilities/departments. The CG presented in this paper extends other related works by incorporating numerous aspects of layout that include empty travel of material handling equipment, information flow, personnel flow and equipment flow.     

应用随机游走的社交网络用户分类方法

针对现有在线社交网络用户分类方法不能有效利用用户属性和关系网络信息提高分类性能的问题,设计了一种基于随机游走模型的多标签分类方法MLCMRW。该方法的分类过程包括学习用户初始化类别标签以及通过迭代推理获得用户稳定标签分布两个阶段,并且其可以同时考虑用户属性以及关系网络特征信息进行分类。多个在线社交网络数据集上进行的实验表明,MLCMRW比其它已有的代表性方法有更好的分类性能,并且更适合对现实中的在线社交网络进行用户分类。     

Dynamic efficiency evaluation of state-level business incubators in China by using a slacks-based measure approach

It is important to evaluate the efficiency of business incubators for their performance improvement. Because few enterprises can successfully graduate from the incubation process in one incubation period, the incubating enterprises will be carried over to the successive periods. In this context, the number of incubating enterprises can be regarded as a carry-over variable linking different incubation periods, which can also be treated as an undesirable output in the current period. This paper proposes a dynamic slacks-based measure model to evaluate the efficiency of China's state-level business incubators during 2010–2012. The empirical results show that neglecting new entrants and the typical carry-over variable may underestimate the incubation system's efficiency. Moreover, the operational efficiency of China's state-level business incubators is relatively low, which is largely caused by the lower pure technical efficiency. There exist great disparities between pure technical efficiency and scale efficiency for all considered incubators in China. Some important insights and policy suggestions are presented.     

基于渐进服务半径的自提柜选址算法

物流“最后一公里”是直接面向客户服务的物流末端环节,直接影响到物流的效率、成本和服务质量.针对此“最后一公里”问题,提出基于自提柜的末端物流配送解决方案.通过引入自提柜渐进服务半径的概念,用需求点到自提柜的距离来刻画需求点对自提柜的服务满意度,并用凹凸函数来表示,建立自提柜选址问题的混合整数规划模型.同时,充分考虑模型的各项约束性条件,设计出启发式拉格朗日松弛算法并进行模型求解.最后,运用大量算例进行检验,分析算法的迭代次数、迭代时间等指标,证明选址模型的准确性和求解算法的有效性,为实际工程应用提供了理论指导.     

Robust multi‐response surface optimization: a posterior preference approach

This paper discusses the use of multi‐response surface optimization (MRSO) to select the preferred solutions from among various non‐dominated solutions (NDS). Since MSRO often involves conflicting responses, the decision‐maker's (DM) preference information should be included in the model in order to choose the preferred solutions. In some approaches this information is added to the model after the problem is solved. In contrast, this paper proposes a three‐stage method for solving the problem. In the first stage, a robust approach is used to construct a regression model. In the second phase, non‐dominated solutions are generated by the ε‐constraint approach. The robust solutions obtained in the third phase are NDS that are more likely to be Pareto solutions during consecutive iterations. A simulation study is then presented to show the effective performance of the proposed approach. Finally, a numerical example from the literature is brought in to demonstrate the efficiency and applicability of the proposed methodology.     

公平关切下考虑企业社会责任的物流服务供应链协调

针对由单个物流服务集成商(LSI)和单个功能型物流服务提供商(FLSP)组成的物流服务供应链(LSSC),考虑LSI的企业社会责任(CSR)和FLSP的物流服务水平,研究LSI和FLSP的公平关切偏好在成本分担契约和成本分担-两部关税的组合契约下对LSSC最优决策、各成员利润和整体利润以及供应链协调性的影响.研究表明:公平关切偏好不影响LSSC在不同契约下的协调状态,但影响LSSC成员的利润;成本分担-两部关税的组合契约能实现LSI和FLSP的双赢.LSI在成本分担契约下应降低自己的公平关切偏好并与公平关切偏好程度较低的FLSP合作,在成本分担-两部关税的组合契约下应增加自身的公平关切偏好并与公平关切偏好较低的FLSP合作;FLSP在两种契约下都应该增加自身的公平关切偏好并与公平关切偏好较低的LSI合作.     

OSN Crawling Schedulers and Their Implications on k‐Plexes Detection

Web crawlers are complex applications that explore the Web for different purposes. Web crawlers can be configured to crawl online social networks (OSNs) to obtain relevant data about their global structure. Before a web crawler can be launched to explore the Web, a large amount of settings have to be configured. These settings define the crawler's behavior and they have a big impact on the collected data. Both the amount of collected data and the quality of the information that it contains are affected by the crawler settings and, therefore, by properly configuring these web crawler settings we can target specific goals to achieve with our crawl. In this paper, we review the configuration choices that an attacker who wants to obtain information from an OSN by crawling it has to make to conduct his attack. We analyze different scheduler algorithms for web crawlers and evaluate their performance in terms of how useful they are to pursue a set of different adversary goals.     

Flexibility performance: Taguchi's method study of physical system and operating control parameters of FMS

In present manufacturing environment, the manufacturing flexibility has become one of the strategic competitive tools. Flexibility refers to the availability of alternative resources. These resources may have varied parameters, particularly related to physical and operating system. These physical and operating parameters of alternative resources may influence the system's performance with the changing levels of flexibility and operational control parameters such as scheduling rules. Is increase in a flexibility level provides desired improved performance output? If yes, than under what conditions of physical and operating parameters and under which control strategy (CS)? Is improved performance is present at all increasing levels of flexibility? Flexible manufacturing system (FMS) being consist of numerous physical and operating parameters and complex in nature, the solution to these questions can provide an understanding of the productive levels of flexibility for a given physical and operating parameters of an FMS. This paper establishes the need of modelling of the physical and operating parameters of flexible manufacturing system along with flexibility and presents a simulation study under Taguchi's method analysis of these parameters. The paper contributes an approach to study the impact of variations in physical and operating parameters of an FMS and to identify the level of these variations that do not restrict the advantages of flexibility. The results show that the expected benefits from increasing the levels of flexibility and a superior CS may not be achieved if the physical and operating parameters of alternative machines have variations. Taguchi's method analysis indicates that relative percentage contribution of variations in physical and operating parameters of alternative resources should be negligible or minimum in the performance of FMS. Their increasing relative contribution may restrict the advantages of flexibility. If these variations are higher than increase in flexibility level may be counter productive.