Statistical inference in massive data sets

Analysis of massive data sets is challenging owing to limitations of computer primary memory. In this paper, we propose an approach to estimate population parameters from a massive data set. The proposed approach significantly reduces the required amount of primary memory, and the resulting estimate will be as efficient if the entire data set was analyzed simultaneously. Asymptotic properties of the resulting estimate are studied, and the asymptotic normality of the resulting estimator is established. The standard error formula for the resulting estimate is proposed and empirically tested; thus, statistical inference for parameters of interest can be performed. The effectiveness of the proposed approach is illustrated using simulation studies and an Internet traffic data example. Copyright © 2012 John Wiley & Sons, Ltd.     

Evaluation of nanomaterials-grafted enzymes for application in contaminants degradation: Need of the hour with proposed IoT synchronized nanosensor fit sustainable clean water technology in en masse

Increased water pollution and challenges in ultrafast recognition of water pollutants poses considerable burden to the public health. The issue of providing clean water to rural people is always a daunting yet challenging task wherein building a centralized water treatment system along with proper pipeline to connect dispersed population is not at all feasible. Amongst different water treatment technologies, sustainable nanozyme based materials have made an exceptional contribution towards providing contaminants free potable water to mankind due to its strong activity and sensitivity towards chemical substances thus facilitating use in advanced point-of-use (POU) system. In this article, we have briefly highlighted the way by which silica, carbon and MOF based nano support stabilizes the enzyme with its improved selectivity and sensitivity towards water decontamination. The strength of nanozymes and its potential use in POU devices has also been discussed for future research endeavor. Additionally, development of various nano-chemo-sensors with advanced machine learning approach is an added advantage towards detecting various contaminants from real samples with its implementation in POU devices. We have also proposed the implementing strategies of these nanozyme based water technologies so that early adopters can be given an informed decision about its way of implementation in coming days in India.     

Obtaining the optimal cache document replacement policy for the caching system of an EC website

Adopting a proper cache document replacement policy is critical to the performance of a caching system. Among the existing cache document replacement policies, no one policy can surpass all the other policies in every case. Besides, the most suitable cache document replacement policy for a caching system is often chosen from the existing policies, which cannot guarantee the optimality of the chosen policy. These phenomena motivate us to construct a cache document replacement policy which content can be tailored to the specific requirements of a caching system. In this study, the optimal linear combination (OLC) cache document replacement policy tailored to the requirements of the caching system is to be found out. To evaluate the effectiveness of the proposed methodology, an experimental EC website has been constructed, and the log file of the website server was used as the data source to evaluate the performances of various cache document replacement policies under different cache sizes. In our simulation experiments, the OLC policies outperformed the other traditional policies by increasing the hit rate and the byte hit rate up to 7% and 11%, respectively.     

A packet filter placement problem with application to defense against spoofed denial of service attacks

We analyze a problem in computer network security, wherein packet filters are deployed to defend a network against spoofed denial of service attacks. Information on the Internet is transmitted by the exchange of IP packets, which must declare their origin and destination addresses. A route-based packet filter verifies whether the purported origin of a packet is correct with respect to the current route map. We examine the optimization problem of finding a minimum cardinality set of nodes to filter in the network such that no spoofed packet can reach its destination. We prove that this problem is NP-hard, and derive properties that explicitly relate the filter placement problem to the vertex cover problem. We identify topologies and routing policies for which a polynomial-time solution to the minimum filter placement problem exists, and prove that under certain routing conditions a greedy heuristic for the filter placement problem yields an optimal solution.     

Network traffic behaviour near phase transition point

We explore packet traffic dynamics in a data network model near phase transition point from free flow to congestion. The model of data network is an abstraction of the Network Layer of the OSI (Open Systems Interconnect) Reference Model of packet switching networks. The Network Layer is responsible for routing packets across the network from their sources to their destinations and for control of congestion in data networks. Using the model we investigate spatio-temporal packets traffic dynamics near the phase transition point for various network connection topologies, and static and adaptive routing algorithms. We present selected simulation results and analyze them.     

Internet resources for agent-based modelling

The use of agent-based models (ABMs) is steadily increasing in all the disciplines including environmental chemistry and toxicology. This growth is mainly driven by their ability to address problems that conventional modelling techniques cannot, such as the change of scale or the emergence of unanticipated phenomena resulting from interactions between their constitutive goal-directed agents. After a brief introduction on the basic principles of agent-based modelling and the presentation of selected case studies, the main software resources available on the Internet are presented. An attempt is made to estimate the complexity of these tools versus their potentialities and flexibility.     

基于物联网视觉的大型拥堵车辆调度系统设计

针对道路拥堵车辆调度问题,设计了一种基于物联网视觉的大型拥堵车辆调度系统,分析了系统的总体结构,给出了系统的ZigBee协调器模块、车载传感器节点、图像采集处理模块以及无线传输模块的硬件结构,详细介绍了拥堵车辆调度算法流程,并给出了车辆调度最佳路径算法代码,实现了大型拥堵车辆的有效调度。实验结果说明,所设计系统可获取有效的交通车辆拥堵图像,实现交通拥堵的高效调度。     

The use of the Internet for teaching Chemistry

Over the past 20 years there have been astounding advances in computer hardware and software. Many recent developments have focused on the Internet and the World Wide Web (WWW). The Internet has made a huge impact on the way chemists work, but as yet far less on the way they teach.     

国际互联网络（Internet）上的化学及分析化学信息

本文讨论了国际互联网络（Ｉｎｔｅｒｎｅｔ）在化学和分析化学中的应用，通过Ｉｎｔｅｒｎｅｔ可以有效地进行文献检索，获取信息，另外还介绍了查找实例并给出与化学有关的站点。