Hushairi Zen

Fault Detection using Dynamic Parity Space Approach

This paper review the effectiveness of the parity space approach to identify faults or disturbance in a system. The most commonly used is the observer based procedures, and redundancy relationship method. This involves analytical mathematical analysis of geometry and bilinear algebra. Then, technological advances which require complex computation such as artificial intelligence and genetic algorithm had made tremendous improvement to fault Detection and Isolation (FDI) analysis. Dynamic Parity Space Approach was studied for a discrete state-space model. Important data will be extracted using this approach especially for residual generation which is the backbones of FDI analysis. Subsequently, at each time instant k, the generated residuals will form a matrix that will define the fault signature. It is remarkable that this approach is proven in this study to be effective in diagnosis and faults isolation.

End Suction Centrifugal Pump Operating in Turbine Mode for Microhydro Applications

This paper reviews the current research works on the end suction centrifugal pump coupled with induction generator running in turbine mode for microhydro application. The information can be used by practicing engineers, researchers, and plant managers to understand the potential of pump running as turbine. Review on experimental and simulation works was carried out encompassing end suction single stage low specific speed which is less than 10 kW. This is followed by review of their efficiency improvement through modifications. The results show that centrifugal pump can operate in turbine modes without any modification on mechanical components. However, to achieve the best efficiency point (BEP), it requires higher flow rate and head than pumping rating. Efficiency improvement is viable through geometric modification to improve hydraulic characteristic. The studies also show that pump as turbine (PAT) can be directly coupled with modified induction motor as generator by adding capacitor and electric control system, regulating voltage and frequency at the output terminal. It was found that PAT offers the best low cost solution for microhydro application especially for third world countries that do not have local microhydro manufacturer.

Fast association process (FAP) of beacon enabled for IEEE 802.15.4 in strong mobility

In strong mobility the mobile node association with a coordinator (static or mobile) is an important part of IEEE802.15.4 protocol. This research analyzes the mobile node association attempt process flows in detail. This research also proposes an enhanced association procedure names Fast Association Process (FAP) in strong mobility. FAP is introduced with new Association_Data request MAC command that increases the association period and provides fast association process in strong mobility. It reduces the redundant service primitives, avoid collision and decrease association attempt process delay. Comparing FAP with the original IEEE802.15.4 protocol, the number of association service primitives in FAP is 67% less than the original protocol, and the simulation results show that the association attempt time decreases 75%. FAP will get fast association attempt as the number of mobile nodes increased and nodes having strong mobility. It can be widely used in mobile wireless sensor network application.

An optimized travelling time estimation mechanism for minimizing handover failures and unnecessary handovers from cellular networks to WLANs

Purpose – The paper aims to propose an optimized handover necessity estimation scheme for a mobile terminal (MT) traversing from a third-generation (3G) cellular network into the wireless local area network (WLAN) cell for reducing the number of handover failures and unnecessary handovers. Design/methodology/approach – The proposed optimized handover necessity estimation scheme comprises of two algorithms – a “travelling time prediction” reliant on consecutive received signal strength (RSS) measurements and MT’s velocity, and a “time threshold estimation” depending on the handover latency, WLAN’s cell radius, tolerable handover failure probability and the tolerable unnecessary handover probability. Findings – Our performance analysis reveals that the suggested mechanism effectively minimizes the number of handover failures and unnecessary handovers by 60 per cent as compared to the already proposed schemes in the literature. Originality/value – The convergence of Internet and wireless mobile communication...

Numerical Simulation on End Suction Centrifugal Pump Running in Inverse Flow for Microhydro Applications

The initial capital cost for most microhydro projects has always been an overriding issue for self-funded remote communities. The cost will escalate significantly in the absence of local microhydro electromechanical manufacturers. The application of end suction centrifugal pump as turbine will reduce the overall cost, which renders microhydro systems feasible for self-funded projects and are therefore suitable for rural communities. The goal of this study is to design and develop a pump as turbine (PAT) which serves as a substitute to commercial electromechanical components. Numerical analysis of an inverse flow for an end suction centrifugal pump is presented in this paper, which includes the performance curves and hydraulic characteristics of the pump. ANSYS CFX, a commercial CFD software is used to simulate the performance of the pump with specific speed, Ns of 70 units (Euroflo EU50-20). The computational flow domain inside the pump is comprises of impeller, volute and draft tube. Unstructured tetrahedral mesh is used to maintain good surface mesh due to complex flow domain geometries. The governing equations used in the simulations are three-dimensional, incompressible Navier-Stokes and k-ϵ turbulence model under steady-state condition. The simulation results are compared with pump performance curve supplied by the pump manufacturer. The verification results show good agreement for flow rates between 0.7 and 1.3 QBEP. The best efficient point (BEP) for inverse flow is attained at a higher head and flow rate compared to pump mode, whereby the value is found to be 21.55 m and 14.0 l/s, respectively. It is believed that the findings of this study will be useful to predict hydraulic characteristics and performance curves of PAT and the model may be used to identify poor flow characteristics inside the pump. It is recommended that optimization process is carried out using CFD tools in future studies.

Performance evaluation of beacon enabled IEEE 802.15.4 MAC for Mobile Wireless Sensor Networks under NS-2

Wireless Sensor Network (WSN) has a large number of nodes capable of sensing, communicating and computing. WSNs have limitations due to limited storage, processing and transmission power. The IEEE802.15.4 Medium Access Control (MAC) protocol is used for low-rate wireless personal area network (LR-WPAN). LR-WPAN is basically designed for static wireless sensor networks. However, from literatures, we observed that IEEE802.15.4 is able to support weak mobility in mobile sensor networks [7]. This paper evaluates the IEEE802.15.4 MAC for strong mobility in mobile sensor network environments. We evaluate the performance of IEEE802.15.4 MAC based on both static and mobile coordinators, and taking into account two parameters which are speed and number of beacon orders. We observed the effect on association period, disassociation, and synchronization between the mobile node and the coordinator in strong mobility of mobile nodes. From the experiments, we obtained results on throughput, association and synchronization with different speed and beacon orders. We found that the IEEE802.15.4 cannot maintain association period in strong mobility. The weaknesses of mobile node association attempt and synchronization process degrade the overall performance of a network. We also identify some research problems that need to be addressed for successful implementation of MAC protocol with strong mobility in Mobile Wireless Sensor Networks.

A simple and cost effective data acquisition system for mobile satellite experimental work under tree-shadowed and building-shadowed

Signal degradation in Mobile Satellite (MS) is due to several factors such as ionospheric effect, multipath fading, tree-shadowed and building-shadowed. This affects the Mobile Satellite Service (MSS) to provide continuous communication service to the users. Since there is not adequate data available on the signal performance of the MS in the Asian continent, thus, an experimental work is essential to be carried out to investigate the effect of factors such as the tree-shadowed and building-shadowed on the signal strength. This paper discusses the cost effective set up. It can be used to measure the effect of trees and buildings on the received mobile satellite signal operating in the L-band. The methodology uses to carry up the experimental works is discussed in detail. The measurements of the signal performance are performed under different MS environments such as tree-shadowed and building-shadowed and hence the results are compared to the data obtained for open space environment. The analysis of the signal performance under different MS environments is performed with respect to the elevation and azimuth degree at different time under a clear sky condition. The analysis produced forms an important part in the studies of the signal performance. From this research work, we would like to propose a simple and low cost data acquisition system in order to encourage more experimental works to be carried out especially in the less developed countries.

Big Data and Privacy Issues for Connected Vehicles in Intelligent Transportation Systems.

The evolution of Big Data in large-scale Internet-of-Vehicles has brought forward unprecedented opportunities for a unified management of the transportation sector, and for devising smart Intelligent Transportation Systems. Nevertheless, such form of frequent heterogeneous data collection between the vehicles and numerous applications platforms via diverse radio access technologies has led to a number of security and privacy attacks, and accordingly demands for a secure data collection in such architectures. In this respect, this chapter is primarily an effort to highlight the said challenge to the readers, and to subsequently propose some security requirements and a basic system model for secure Big Data collection in Internet-of-Vehicles. Open research challenges and future directions have also been deliberated.

Toward Edge-based Caching in Software-defined Heterogeneous Vehicular Networks

Considerable technological advancements and pervasive use of smart connected vehicles have highlighted the true potential of vehicular networks, which, in the realm of smart cities, assists in improvement of road safety and traffic management and efficiency. Coupled with this is the massive innovation realized in wireless networking technologies, and today, heterogeneous networks encompassing 4G LTE, Wi-Fi, WiMAX, DSRC, and Terahertz communication are taking shape, synergy of which not only promises higher bandwidth but also ensures low latent infrastructure critical for supporting diverse range of safety applications. Heterogeneity, on the other hand, has introduced new challenges too, e.g., in terms of network fragmentation, an unbalanced traffic flow in a multi-path topology, and inefficient utilization of network resources. Accordingly, the emerging yet promising paradigm of software-defined networking (SDN) has, of lately, been introduced to vehicular networks for addressing such bottlenecks, which through its logically centralized control ensures programmability, scalability, elasticity, and agility. Nevertheless, a centralized control in a distributed environment like vehicular networks could become a single point of network failure and may also result in significant network management overhead in case of extremely dense traffic scenarios. Therefore, leveraging edge-based caching in heterogeneous vehicular networks is indispensable. This chapter brings forward the notion of SDN-based heterogeneous vehicular networking and argues that edge-based caching can help overcome the bottlenecks posed by traditional networking architectures especially in terms of ensuring low latency for safety-critical applications. Finally, open challenges and probable solutions are discussed.

Vertical Handover Decision Schemes in Fourth Generation Heterogeneous Cellular Networks: A Comprehensive Study

Vertical Handover Decision (VHD) algorithms are indispensable components of forthcoming 4G heterogeneous wireless networks architecture – so as to provide requisite Quality of Service to an assortment of applications anywhere at any time, while allowing seamless roaming in highly dynamic scenarios (i.e. multitude of access network technologies that vary in bandwidth, latency, monetary cost, etc.) using Mobile Terminals (MTs) enabled with multiple access interfaces. In this article, a critical review of the existing VHD algorithms has been carried out as an effort to update the previous studies. To offer a methodical contrast, recently published VHD algorithms have been classified into four major classes depending on the key handover decision criterion used, i.e. RSS based algorithms, bandwidth based algorithms, cost function based algorithms, and the combination algorithms. Moreover, operational fundamentals, advantages, and disadvantages of exemplary VHD algorithms for each class have been presented to assess the tradeoffs between their intricacy of implementation and the efficacy. Copyright