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1.Speed Tracking Based Energy-Efficient Freight Train Control Through Multi-Algorithms Combination

Author:Yang, J;Jia, LM;Fu, YX;Lu, SF


Abstract:Based on the characteristics of freight train control, which are nonlinear, time-delay, with multi-constraint and multiobjective, this paper focuses on speed tracking problem. Firstly, in a gradual process, a multi-modal fuzzy PID (MM-FPID) control algorithm is presented on the basis of a brief analysis of PI and PID control, which is generally used to train control in active services. Secondly, in order to deal with the time-delay problem of freight train, the paper adopts an approach of traction force feed-forward, which greatly improves the dynamic performance of the controller. Thirdly, for the overspeed brake problem caused by speed overshoot, the strategy of adaptive traction force limitation is adopted, and we get satisfactory results without increasing the safety speed margin. Fourthly, inspired by the selflearning characteristic of neural networks (NNs), an integrated controller of MM-FPID and NNs is proposed. Finally, with the help of a computer simulation platform, the paper puts forward a set of simulations, comparing the MM-FPID and the integrated control method with classical PID and fuzzy control. The results show that both MM-FPID and the integrated controller has satisfactory control effect, and their multi-modal structure makes it easy to fit different applications well, while the integrated controller has more potential in self-learning.

2.Energy Dissipation During Impact of an Agglomerate Composed of Autoadhesive Elastic-Plastic Particles

Author:Liu, LF;Thornton, C;Shaw, SJ


Abstract:Discrete Element Method is used to simulate the impact of agglomerates consisting of autoadhesive, elastic-plastic primary particles. In order to explain the phenomenon that the elastic agglomerate fractures but the elastic-plastic agglomerate disintegrates adjacent to the impact site for the same impact velocity, we increase the impact velocity and lower the yield strength of the constituent particles of the agglomerate. We find that increasing the impact velocity can lead to the increased number of yielded contacts, and cause the elastic-plastic agglomerate to disintegrate faster. Mostly importantly, the energy dissipation process for the elastic-plastic agglomerate impact has been investigated together with the evolutions of the yielding contacts, and evolutions of velocity during impact.

3.Minimize Reactive Power Losses of Dual Active Bridge Converters using Unified Dual Phase Shift Control

Author:Wen, HQ;Su, B


Abstract:This paper proposed an unified dual-phase-shift (UDPS) control for dual active bridge (DAB) converters in order to improve efficiency for a wide output power range. Different operating modes of UDPS are characterized with respect to the reactive current distribution. The proposed UDPS has the same output power capability with conventional phase-shift (CPS) method. Furthermore, its implementation is simple since only the change of the leading phase-shift direction is required for different operating power range. The proposed UDPS control can minimize both the inductor rms current and the circulating reactive current for various voltage conversion ratios and load conditions. The optimal phase-shift pairs for two bridges of DAB converter are derived with respect to the comprehensive reactive power loss model, including the reactive components delivered from the load and back to the source. Simulation and experimental results are illustrated and explained with details. The effectiveness of the proposed method is verified in terms of reactive power losses minimization and efficiency improvement.

4.Quantitative and rapid detection of microcystin-LR using time-resolved fluorescence immunochromatographic assay based on europium nanospheres

Author:Zhang, Y;Ding, XL;Guo, MM;Han, TT;Huang, ZJ;Shang, HT;Huang, B


Abstract:In the present study, a novel time-resolved fluorescence immunochromatographic assay was established for the rapid quantitative detection of microcystin-leucine arginine (MC-LR). In this method, the europium nanoshpere labelled with anti-MC-LR antibodies was used as the luminescent tracer, dissolved in the running buffer and then added with the sample solution on the pad. MC-LR-BSA and goat anti-mouse antibody were dispensed on the nitrocellulose membrane for the test and the control line, respectively. The optimal parameters were 0.05 g L-1 MC-LR-BSA, 1 : 100 colloidal europium-antibody conjugate, and 10 min reaction time. The linear working range for MC-LR was 0.1-5 mu g L-1 with an IC50 of 0.78 mu g L-1 and a sensitivity of 0.035 mu g L-1. The low cross-reactivity was observed with MC-YR and MC-LF. The assay accuracy was confirmed by the HPLC method with a correlation coefficient of 0.99. When the variable coefficients were 4.4%% and 5.4%%, the average recoveries of tap and lake water were 94.6%% and 102.8%%, respectively. The time-resolved fluorescence immunochromatographic assay provides a sensitive, simple, and speedy performance for MC-LR quantitative determination and has a potential use for water sample screening.

5.Parametric investigation of polymethacrylate monolith synthesis and stability via thermogravimetric characterisation

Author:Acquah, C;Danquah, MK;Moy, CKS;Anwar, M;Ongkudon, CM


Abstract:Polymethacrylate monoliths are synthetic adsorbents with macroporous and mesoporous interconnected channels that can be engineered to target the hydrodynamic features of a wide range of molecular species. However, rigorous study into the effect of synthesis conditions on their thermal stability is limited. This work attempts to characterise the influence of key synthesis process variables on the stability of polymethacrylate monoliths using thermogravimetric analysis at a heating rate of 10 degrees C/min. Experimental results showed that the thermal stability of polymethacrylate monoliths increased with decreasing polymerisation temperature from 85 to 65 degrees C. Increasing the total porogen (P) to monomer (M) ratio increased the thermal stability of the monolith by >62%% and >50%% for P40/M60-P60/M40 and P60/M40-P80/M20, respectively. The impact of the initiator concentration, monomer variation, biporogen ratio, washing and activation of the monoliths was investigated. Nuclear magnetic resonance analyses conducted confirmed the hydrolysis of epoxy moieties on the monolith. (C) 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

6.Combinations of fungal and milling pretreatments for enhancing rice straw biogas production during solid-state anaerobic digestion

Author:Mustafa, AM;Poulsen, TG;Xia, YH;Sheng, KC


Abstract:Rice straw was pretreated by different combinations of physical (milling) and biological (incubation with Pleurotus ostreatus fungus) treatment to improve its biodegradability and biogas production during solid-state anaerobic digestion (SS-AD). Effects of milling (62 mm) and incubation time (10, 20 and 30 d), on lignin, cellulose, and hemicellulose degradation during fungal pretreatment and methane yield during digestion were assessed by comparison with untreated rice straw. Both incubation time and milling had significant impacts on both lignin removal during fungal pre-treatment and methane yield during digestion. A combination of fungal pretreatment at 30 days followed by milling prior to anaerobic digestion resulted in 30.4%% lignin removal, the highest selectivity value (the ratio between relative lignin removal and relative cellulose removal) of 4.22, and the highest methane yield of 258 L/kg VS. This was equivalent to a 165%% increase in methane yield from SS-AD compared to untreated rice straw. (C) 2016 Elsevier Ltd. All rights reserved.

7.Cross-VM cache-based side channel attacks and proposed prevention mechanisms: A survey

Author:Anwar, S;Inayat, Z;Zolkipli, MF;Zain, JM;Gani, A;Anuar, NB;Khan, MK;Chang, V


Abstract:The state-of-the-art Cloud Computing (CC) has been commercially popular for shared resources of third party applications. A cloud platform enables to share resources among mutually distrusting CC clients and offers cost-effective, on-demand scaling. With the exponential growth of CC environment, vulnerabilities and their corresponding exploitation of the prevailing cloud resources may potentially increase. Although CC provides numerous benefits to the cloud computing tenant. However, features namely resource sharing and Virtual Machine (VM) physical co-residency raising the potential for sensitive information leakages such as Side Channel (SC) attacks. In particular, the physical co-residency feature allows attackers to communicate with another VM on the same physical machine and leak the confidential information due to inadequate logical isolation. Unlike encryption, which protects information from being decoded by unauthorized persons, SC attacks aim to exploit the encryption systems and to hide the occurrence of communication. SC attacks were initially identified as the main threat on multi-level secure systems i.e. OS, database, and networks. More recently, the focus of the researchers has shifted toward SC attacks in CC. Since the last level cache (L2 or L3) is always shared between VM, is the most targeting device for these attacks. Therefore, the aim of this article is to explore cross-VM SC attacks involving the CPU cache and their countermeasures in CC and to compare with the traditional SC attacks and countermeasures. We categorized the SC attacks according to the hardware medium they target and exploit, the ways they access the module and the method they use to extract confidential information. We identified that traditional prevention mechanisms for SC attacks are not appropriate for prevention of cross-VM cache-based SC attacks. We also proposed countermeasures for the prevention of these attacks in order to improve security in CC.

8.An improved method for predicting discharge of homogeneous compound channels based on energy concept

Author:Tang, XN


Abstract:Accurate estimation of flow discharge in a compound river channel is increasingly important in river management and hydro-environment design. In this paper, a new model is developed to improve the prediction of flow based on Energy Concept Method (ECM) and Weighted Divided Channel Method (WDCM) along with the apparent shear stress at the interface between main channel and floodplain. The new model is compared with a wide range of our experimental data and the data available in the literature. The 27 datasets used include homogenous symmetric channels (22 datasets) and asymmetric channels (5 datasets) with various aspect ratios [channel total width (B) at bankfull / main channel bottom (b) =1.5-15.8], and bed slopes (S-0 = 4.3 x 10(-4)-1.3 x 10(-2)). It was found that the new model has significantly improved the accuracy of flow prediction compared with the traditional Divided Channel Method (DCM), and has also considerably better results than the ECM and WDCM methods against all the datasets, particularly for relatively low flow depths of floodplain where the flow discharges are most difficult to predict correctly. The new model predicts the total discharge well for both symmetric and asymmetric channels, within an averaged relative error of about 5%%.

9.SmallClient for big data: an indexing framework towards fast data retrieval

Author:Siddiqa, A;Karim, A;Chang, V


Abstract:Numerous applications are continuously generating massive amount of data and it has become critical to extract useful information while maintaining acceptable computing performance. The objective of this work is to design an indexing framework which minimizes indexing overhead and improves query execution and data search performance with optimum aggregation of computing performance. We propose SmallClient, an indexing framework to speed up query execution. SmallClient has three modules: block creation, index creation and query execution. Block creation module supports improving data retrieval performance with minimum data uploading overhead. Index creation module allows maximum indexes on a dataset to increase index hit ratio with minimized indexing overhead. Finally, query execution module offers incoming queries to utilize these indexes. The evaluation shows that SmallClient outperforms Hadoop full scan with more than 90%% search performance. Meanwhile, indexing overhead of SmallClient is reduced to approximately 50 and 80%% for index size and indexing time respectively.

10.Customer churn prediction in the telecommunication sector using a rough set approach

Author:Amin, A;Anwar, S;Adnan, A;Nawaz, M;Alawfi, K;Hussain, A;Huang, KZ


Abstract:Customer churn is a critical and challenging problem affecting business and industry, in particular, the rapidly growing, highly competitive telecommunication sector. It is of substantial interest to both academic researchers and industrial practitioners, interested in forecasting the behavior of customers in order to differentiate the churn from non-churn customers. The primary motivation is the dire need of businesses to retain existing customers, coupled with the high cost associated with acquiring new ones. A review of the field has revealed a lack of efficient, rule-based Customer Churn Prediction (CCP) approaches in the telecommunication sector. This study proposes an intelligent rule-based decision-making technique, based on rough set theory (RST), to extract important decision rules related to customer churn and non-churn. The proposed approach effectively performs classification of churn from non-churn customers, along with prediction of those customers who will churn or may possibly churn in the near future. Extensive simulation experiments are carried out to evaluate the performance of our proposed RST based CCP approach using four rule-generation mechanisms, namely, the Exhaustive Algorithm (EA), Genetic Algorithm (GA); Covering Algorithm (CA) and the LEM2 algorithm (LA). Empirical results show that RST based on GA is the most efficient technique for extracting implicit knowledge in the form of decision rules from the publicly available; benchmark telecom dataset. Further, coniparative results demonstrate that our proposed approach offers a globally optimal solution for CCP in the telecom sector, when benchmarked against several state-of-the-art methods. Finally, we show how attribute-level analysis can pave the way for developing a successful customer retention policy that could form an indispensable part of strategic decision making and planning process in the telecom sector.

11.Unusual formation of tetragonal microstructures from nitrogen-doped carbon nanocapsules with cobalt nanocores as a bi-functional oxygen electrocatalyst

Author:Hu, EL;Ning, JQ;He, B;Li, ZP;Zheng, CC;Zhong, YJ;Zhang, ZY;Hu, Y


Abstract:A facile non-template solid-state reaction method has been developed for the first time preparation of a tetragonal microstructure self-assembled from nitrogen-doped carbon nanocapsules containing metallic cobalt nanoparticles (Co-N-C) by using graphitic carbon nitride (g-C3N4) and Co(CH3COO)(2)center dot 4H(2)O as the only reactants, in which g-C3N4 acts as the effective source of nitrogen and carbon elements in the N-doped carbon nanocapsules and Co(CH3COO)(2)center dot 4H(2)O controls the microscopic structure of the self-assembled product. The as-prepared Co-N-C tetragonal microstructures exhibit enhanced electrocatalytic activities for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The synergistic effect of the chemical compositions and the robust microstructure made of the interconnected N-doped carbon nanocapsules accounts for the superior ORR and OER activity and stability to the commercial Pt/C electrocatalyst. The synthetic strategy presented in this work demonstrates a new avenue for developing highly active carbon-based electrocatalysts for electrochemical energy storage and conversion.

12.From Intrusion Detection to an Intrusion Response System: Fundamentals, Requirements, and Future Directions

Author:Anwar, S;Zain, JM;Zolkipli, MF;Inayat, Z;Khan, S;Anthony, B;Chang, V


Abstract:In the past few decades, the rise in attacks on communication devices in networks has resulted in a reduction of network functionality, throughput, and performance. To detect and mitigate these network attacks, researchers, academicians, and practitioners developed Intrusion Detection Systems (IDSs) with automatic response systems. The response system is considered an important component of IDS, since without a timely response IDSs may not function properly in countering various attacks, especially on a real-time basis. To respond appropriately, IDSs should select the optimal response option according to the type of network attack. This research study provides a complete survey of IDSs and Intrusion Response Systems (IRSs) on the basis of our in-depth understanding of the response option for different types of network attacks. Knowledge of the path from IDS to IRS can assist network administrators and network staffs in understanding how to tackle different attacks with state-of-the-art technologies.

13.Compliance Current Effect on Switching Behavior of Hafnium Oxide based RRAM

Author:Qi, YF;Zhao, C;Fang, YX;Lu, QF;Liu, CG;Yang, L;Zhao, CZ


Abstract:In this study, we compared the basic switching behaviors of HfO2, Al2O3 and HfAlOx (Hf:Al=9:1) based RRAM with Ti top electrode by setting various compliance currents (1mA, 5mA, 10mA, 15mA). The resistance ratio of HfO2 based RRAM (20 -> 320) increases with compliance current whereas it drops not obviously for Al2O3 based RRAM (85 -> 54). HfAlOx (Hf:Al=9:1)) based one has the best resistance ratio (300-440) and resistance stability. All low resistance state (LRS) resistance values of three samples are around 100 Omega with large compliance current while there is a difference in HRS resistance which causes the ratio difference accordingly. The dominant mechanism of resistive switching is the formation and rupture of the conductive filament composed of oxygen vacancies. The appropriate compliance current selection and doping technology to high-k materials should be considered in further study.

14.Spatial Indexing for Data Searching in Mobile Sensing Environments

Author:Zhou, YC;De, S;Wang, W;Moessner, K;Palaniswami, MS


Abstract:Data searching and retrieval is one of the fundamental functionalities in many Web of Things applications, which need to collect, process and analyze huge amounts of sensor stream data. The problem in fact has been well studied for data generated by sensors that are installed at fixed locations; however, challenges emerge along with the popularity of opportunistic sensing applications in which mobile sensors keep reporting observation and measurement data at variable intervals and changing geographical locations. To address these challenges, we develop the Geohash-Grid Tree, a spatial indexing technique specially designed for searching data integrated from heterogeneous sources in a mobile sensing environment. Results of the experiments on a real-world dataset collected from the SmartSantander smart city testbed show that the index structure allows efficient search based on spatial distance, range and time windows in a large time series database.

15.Spectral analysis of the generalized shift-splitting preconditioned saddle point problem

Author:Ren, ZR;Cao, Y;Niu, Q


Abstract:A shift-splitting preconditioner was recently proposed for saddle point problems, which is based on a generalized shift-splitting of the saddle point matrix. We provide a new analysis to prove that the corresponding shift-splitting iteration method is unconditional convergent. To further show the efficiency of the shift-splitting preconditioner, the eigenvalue distribution of the shift-splitting preconditioned saddle point matrix is investigated. We show that all eigenvalues having nonzero imaginary parts are located in an intersection of two circles and all real eigenvalues are located in a positive interval. Numerical examples are given to confirm our theoretical results. (C) 2016 Elsevier B.V. All rights reserved.

16.Efficient Path Planning Methods for UAVs Inspecting Power Lines

Author:Rafanavicius, V;Cimmperman, P;Taluntis, V;Man, KL;Volkvicius, G;Jurkynas, M;Bezaras, J


Abstract:Power line inspection is one of the most difficult and time consuming steps in power line maintenance. Even for a sizeable group of workers it takes months to inspect all of them, especially when they are not visible from the road and must be inspected on foot or with an aerial vehicle. That problem is even more prominent when the inspection must be done as fast as possible when the power cuts out in certain regions after natural disaster. To save time and reduce expenditure Unmanned Aerial Vehicles (UAV) could be used to film the power lines and automatically find problems (e.g. a broken cable or a tree branch too close to the a line). Our research focuses on planning the route for the survey.

17.Au-Free AlGaN/GaN MIS-HEMTs With Embedded Current Sensing Structure for Power Switching Applications

Author:Sun, RZ;Liang, YC;Yeo, YC;Zhao, CZ


Abstract:AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) have become a promising candidate for use in efficient power conversion applications. In order to realize converter circuit control function and overcurrent protection of device itself, we have designed, fabricated, and experimentally measured the Au-free AlGaN/GaN MIS-HEMTs with embedded current sensing structure. A floating ohmic current sensing electrode is inserted between source and gate electrode of which the sensing voltage signal can represent the drain current. We have achieved stable current sensing ratios at various operating conditions including quasi-static, transient state, and under high temperature. The proposed structure is highly useful in monolithic power integrated circuit on CMOS-compatible AlGaN/GaN technologies.

18.Interrelation of structure and operational states in cascading failure of overloading lines in power grids

Author:Xue, F;Bompard, E;Huang, T;Jiang, L;Lu, SF;Zhu, HY


Abstract:As the modern power system is expected to develop to a more intelligent and efficient version, i.e. the smart grid, or to be the central backbone of energy internet for free energy interactions, security concerns related to cascading failures have been raised with consideration of catastrophic results. The researches of topological analysis based on complex networks have made great contributions in revealing structural vulnerabilities of power grids including cascading failure analysis. However, existing literature with inappropriate assumptions in modeling still cannot distinguish the effects between the structure and operational state to give meaningful guidance for system operation. This paper is to reveal the interrelation between network structure and operational states in cascading failure and give quantitative evaluation by integrating both perspectives. For structure analysis, cascading paths will be identified by extended betweenness and quantitatively described by cascading drop and cascading gradient. Furthermore, the operational state for cascading paths will be described by loading level. Then, the risk of cascading failure along a specific cascading path can be quantitatively evaluated considering these two factors. The maximum cascading gradient of all possible cascading paths can be used as an overall metric to evaluate the entire power grid for its features related to cascading failure. The proposed method is tested and verified on IEEE30-bus system and IEEE118-bus system, simulation evidences presented in this paper suggests that the proposed model can identify the structural causes for cascading failure and is promising to give meaningful guidance for the protection of system operation in the future. (C) 2017 Elsevier B.V. All rights reserved.

19.Energy cost minimization with job security guarantee in Internet data center

Author:Li, ZJ;Ge, JD;Li, CY;Yang, HJ;Hu, HY;Luo, B;Chang, V


Abstract:With the proliferation of various big data applications and resource demand from Internet data centers (IDCs), the energy cost has been skyrocketing, and it attracts a great deal of attention and brings many energy optimization management issues. However, the security problem for a wide range of applications, which has been overlooked, is another critical concern and even ranked as the greatest challenge in IDC. In this paper, we propose an energy cost minimization (ECM) algorithm with job security guarantee for IDC in deregulated electricity markets. Randomly arriving jobs are routed to a FIFO queue, and a heuristic algorithm is devised to select security levels for guaranteeing job risk probability constraint. Then, the energy optimization problem is formulated by taking the temporal diversity of electricity price into account. Finally, an online energy cost minimization algorithm is designed to solve the problem by Lyapunov optimization framework which offers provable energy cost optimization and delay guarantee. This algorithm can aggressively and adaptively seize the timing of low electricity price to process workloads and defer delay-tolerant workloads execution when the price is high. Based on the real-life electricity price, simulation results prove the feasibility and effectiveness of proposed algorithm. (C) 2016 Elsevier B.V. All rights reserved.

20.L2P2: A location-label based approach for privacy preserving in LBS

Author:Sun, G;Liao, D;Li, H;Yu, HF;Chang, V


Abstract:The developments in positioning and mobile communication technology have made the location-based service (LBS) applications more and more popular. For privacy reasons and due to lack of trust in the LBS providers, k-anonymity and 1-diversity techniques have been widely used to preserve privacy of users in distributed LBS architectures in Internet of Things (IoT). However, in reality, there are scenarios where the locations of users are identical or similar/near each other in IoT. In such scenarios the k locations selected by k-anonymity technique are the same and location privacy can be easily compromised or leaked. To address the issue of privacy preservation, in this paper, we introduce the location labels to distinguish locations of mobile users to sensitive and ordinary locations. We design a location-label based (LLB) algorithm for protecting location privacy of users while minimizing the response time for LBS requests. We also evaluate the performance and validate the correctness of the proposed algorithm through extensive simulations. (C) 2016 Elsevier B.V. All rights reserved.
Total 184 results found
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