The importance of wireless sensor networks in structural health monitoring is unceasingly growing, because of the increasing demand for both safety and security in the cities. The speedy growth of wireless technologies has considerably developed the progress of structural monitoring systems with the combination of wireless sensor network technology. Wireless sensor network–based structural health monitoring system introduces a novel technology with compelling advantages in comparison to traditional wired system, which has the benefits of reducing installation and maintenance costs of structural health monitoring systems. However, structural health monitoring has brought an additional complex challenges in network design to wireless sensor networks. This article presents a contemporary review of collective experience the researchers have gained from the application of wireless sensor networks for structural health monitoring. Technologies of wired and wireless sensor systems are investigated along with wireless sensor node architecture, functionality, communication technologies, and its popular operating systems. Then, comprehensive summaries for the state-of-the-art academic and commercial wireless platform technologies used in laboratory testbeds and field test deployments for structural health monitoring applications are reviewed and tabulated. Following that, classification taxonomy of the key challenges associated with wireless sensor networks for structural health monitoring to assist the researchers in understanding the obstacles and the suitability of implementing wireless technology for structural health monitoring applications are deeply discussed with available research efforts in order to overcome these challenges. Finally, open research issues in wireless sensor networks for structural health monitoring are explored.

Information Retrieval (IR) systems are currently facing a continuous challenge due to the increasing size of datasets. Extremely, large data from different aspects is gathered each day resulting in huge increase in the scale of the raw data available across the internet. Indexing, as the main function of IR systems, is becoming a time-consuming problem. Therefore, efficient indexing of a large volume of data is now a critical requirement of modern IR systems. High performance indexing is performed nowadays over the use of MapReduce programming model. MapReduce is a programming paradigm that enables massive processing and large collections distribution across multiple (hundreds or thousands) commodity computers. To shed some light on this issue, this paper presents a detailed performance analysis of distributed indexing for Solr, Katta and Terrier with the context of MapReduce. In particular, this study compares and analyzes the distributed indexing performance of three frameworks using 1GB, 3GB, 6GB, and 9GB subsets of TREC dataset as the processing power increase. The experiments measure the indexing average time, then throughput, speedup, and efficiency of indexing process. The results show that, Terrier performance is the best in the presence of large collections and scalable processing power. While, Solr performance is the best when having limited computing power and small document collections. Finally, the experimental results show that, Katta produced the worst indexing average time among the three frameworks but its speedup scales linearly with processing power and collection size