Forthcoming articles

International Journal of Wireless and Mobile Computing

International Journal of Wireless and Mobile Computing (IJWMC)

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International Journal of Wireless and Mobile Computing (36 papers in press)

Regular Issues

  • Bimanual gesture recognition based on convolution neural network   Order a copy of this article
    by Hao Wu, Gongfa Li, Ying Sun, Guozhang Jiang, Du Jiang 
    Abstract: Gesture recognition is a key research field in human-computer interaction. At present, most researchers focus on one-handed gesture recognition, but do not pay much attention to bimanual (two hands) gesture recognition. This paper presents a deep learning-based solution to tackle the self-occlusion and self-similarity. To solve this problem, this paper uses Kinect to collect many colour and depth images of different gestures, and each gesture contains multiple sample individuals. Colour images and depth images are used to train the recognition model of bimanual gesture, and then fused the colour image and depth image, and train the bimanual gesture recognition model based on colour image and depth image fusion. Then the bimanual recognition effects of three models are compared. The experimental results show that, regardless of the single gesture precision or the mean average precision, the bimanual gesture recognition effect of the fused model is better than the gesture recognition models based on colour image or depth image.
    Keywords: gesture recognition; bimanual gesture; deep learning; CNN; occlusion.

  • Delay threshold scheduling algorithm for LTE downlink systems   Order a copy of this article
    by Fu-Min Chang, Hsiu-Lang Wang, Po-Hsueh Wang, Shang-Juh Kao 
    Abstract: Modified Largest Weighted Delay First (M-LWDF), Exponential Proportional Fair (EXP/PF), and Channel Dependent Earliest Due Date (CD-EDD) are among the algorithms most commonly referenced for the scheduling of requests in real-time multimedia applications using LTE downlink systems. These methods take into account channel conditions as well as packet delays in the dispatch of packets. However, when using M-LWDF, a failure to prioritise packets approaching their delay budget may lead to their exclusion. Conversely, when using CD-EDD or EXP/PF, packets with good channel conditions and short wait times may not be scheduled due to selection criteria emphasising packets that are closest to expiration. This paper proposes a delay threshold scheduling (DTS) algorithm that takes into account channel conditions as well as the packet waiting time. Delay thresholds were adopted to enable the differentiation of packets in conjunction with proportional weighting between channel conditions and packet waiting time for the prioritisation of real-time services. Simulation results demonstrate that compared to the results obtained using M-LWDF, EXP/PF, and CD-EDD, the proposed DTS algorithm is able to increase video traffic throughput and decrease packet delays and the packet loss ratio for real-time services.
    Keywords: downlink scheduling; delay threshold; channel condition; packet waiting time.

  • Multicast stable path routing protocol for wireless ad-hoc networks   Order a copy of this article
    by K.S. Saravanan, N. Rajendran 
    Abstract: Wireless Ad-Hoc Networks (WANETs) enable steady communication between moving nodes through multi-hop wireless routing path. The problem identified is how to improve the lifetime of the route and reduce the need for route maintenance. This helps to save bandwidth and reduce the congestion control available in the network. This paper aims to focus on redesign and development of multicast stable path routing protocol with special features that determine long-living routes in these networks. An extensive ns-2 simulation based performance has been analysed of three widely recognised stability oriented wireless ad-hoc network routing protocols, namely are Associativity Based Routing (ABR) protocol, Flow Oriented Routing Protocol (FORP) and Lifetime Route Assessment Based Routing Protocol (LRABP). The order of ranking of the protocols in terms of packet delivery ratio, average hop count per route, end-to end delay per packet and the number of route transitions is presented.
    Keywords: wireless ad-hoc networks; multicast routing protocol; wireless communication; routing protocol.

  • On optimisation of a web crawler system on the scrapy framework   Order a copy of this article
    by Kaiying Deng, Senpeng Chen, Jingwei Deng 
    Abstract: With the continuous development of internet technology, life is accompanied by data at all times. However, network data is so complicated and confusing that it has become difficult for users to find valuable information. Therefore, being able to acquire data from a vast data ocean has become an essential skill for today's business development. In this paper, a web crawler system based on the scrapy framework is optimised to further enhance the crawler efficiency, increase the crawler speed, and break the crawler limit.
    Keywords: network data; scrapy framework; web crawler; optimisation.

  • Optimal allocation of water resources by multi-objective evolutionary algorithm based on decomposition   Order a copy of this article
    by Wenjun Wang, Hui Wang 
    Abstract: Optimal allocation of water resources (OAWR) is a constrained multi-objective optimisation problem, which aims to allocate limited water resources to different water-use departments and maximise the economic, social, and environmental benefits. Multi-objective evolutionary algorithm based on decomposition (MOEA/D) is a well-known multi-objective optimisation algorithm, which has shown excellent performance on various benchmark and practical problems. In this paper, we try to use MOEA/D to solve the OAWR problem with two objectives and multiple constraints. A normalised method is used to handle the equality constraint. To deal with inequality constraints, a penalty strategy is employed. Simulation results show that our approach can obtain good spacing of solution points along the Pareto front. According to the preferences, the decision makers can choose different allocation strategies from the Pareto front.
    Keywords: optimisation; water resources; optimal allocation; decomposition; multi-objective optimisation.

  • Comparative analysis of fuzzy logic and AHP method for QoS management in LTE networks: IMS case study   Order a copy of this article
    by Ouafae Kasmi, Nawal Ait Aali, Amine Baina, Mostafa Bellafkih, Loubna Echabbi 
    Abstract: In recent years, increasing demand for IP Multimedia Subsystem (IMS) services raised several problems and challenges concerning the quality of service (QoS) management. Thus, each operator has to make its network more efficient for ensuring an acceptable level of QoS. The 3rd Generation Partnership Project (3GPP) offers several scenarios for providing services, but without any control and correction for QoS degradation. However, reaching the QoS satisfaction becomes more difficult and complicated due to changes in preferences and mobility of customers. In this regard, a new approach of multi-level criticality for managing the customers request for guaranteeing a QoS at any time is proposed. To achieve this goal, several criteria are used for making-decision to offer the appropriate QoS level to the customers according to their levels of criticality. In this paper, a comparative analysis of the fuzzy logic and Analytic Hierarchy Process (AHP) methods for multi-criteria has been presented to evaluate QoS and Criticality levels for QoS management in the IMS network. The simulation results describe the comparison between these two methods to illustrate their feasibility for QoS management to find which one gives better results in the aspect of the chance value of QoS and criticality levels.
    Keywords: multi-level criticality; QoS; multi-criteria; fuzzy logic; AHP.

  • Intervention algorithm for malicious information in online social networks based on trusted regulator   Order a copy of this article
    by Deyu Yuan, Haichun Sun, Zhi Zhang, Han Ye, Shuhua Huang 
    Abstract: A lot of malicious information such as rumours is hidden in the massive data flow in social online networks. Once this type of malicious information spreads, it can affect social stability in severe cases. This paper introduces the concept of a trusted regulator to select key nodes, and we propose a method to hinder the rapid spread of malicious information by blocking accounts and publishing clarification, so that the external disturbances from the chosen nodes and the malicious information could fight against each other. Local control strategy is applied to the propagation of malicious information. Specifically, we first introduce the SIMRT model and an importance indicator based on edge weight, then we propose the reverse intervention algorithm based on the importance indicator. Experiment results on different data sets show that the proposed algorithm can effectively suppress the spread of malicious information.
    Keywords: malicious information; online social networks; reverse intervention.

  • Detection and fine-grained classification of malicious code using convolutional neural networks and swarm intelligence algorithms   Order a copy of this article
    by Dongzhi Cao, Xinglan Zhang, Yang Cao, Yuehan Wang, Weixin Liu 
    Abstract: With the development of society, network security has received more and more attention. Malicious code has also grown, causing network security vulnerabilities and increasing threats to internet security. Therefore, the detection of malicious code becomes very important. However, there are some problems in the current research on malicious code detection, for example, tedious feature extraction and unbalanced data, which is far from the effect people want to achieve. To address these problems, in this paper, we proposed a novel malicious code detection and fine-grained classification model by using convolutional neural networks and swarm intelligence algorithms. We converted the binary executable files of malicious codes into grayscale images and then used convolution neural networks to detect and classify malicious codes. In addition, we employed swarm intelligence algorithms to achieve fine-grained classification on unbalanced data in different malicious code families. We conducted a series of experiments on the real malware dataset from the Vision Research Lab. The experimental results demonstrated that the proposed solution is effective and efficient to identify malicious codes.
    Keywords: malicious code; unbalanced data; fine-grained classification; swarm intelligence algorithms.

  • Effective storage location assignment model based on an genetic simulation annealing algorithm   Order a copy of this article
    by Li Zhou, Xi Yang, Lei Chen, Siqing You, Feng Li, Yang Cao 
    Abstract: Automated warehouses have become the main application equipment in logistics owing to their access automation and simple operation. In order to adapt to the increasingly rapid logistics speed, it is necessary to optimise the location assignment of items in the automated warehouse. Firstly, according to the characteristics of the automated warehouse operation environment, the storage location assignment optimisation model with the shortest time of items travelling through the warehouse, the minimum distance between related items and the lowest orthocentre of the shelf is proposed. Then, according to the characteristics of the optimisation model and the shortcomings of the traditional genetic algorithm (GA), the defects of the GA are improved and the fusion with the simulated annealing algorithm (SA) is completed, so as to form an improved genetic simulation annealing algorithm (SAGA) for the model. Finally, the effectiveness and superiority of the improved fusion algorithm are verified by comparing the SA, the SAGA and the improved SAGA.
    Keywords: automated warehouse; storage location assignment optimization; improved SAGA; reversed operator.

  • Numerical study on non-ventilated flame diffusion characteristics in aero-engine nacelle   Order a copy of this article
    by Yu Zheng, Guanbing Cheng, Guoda Wang, Shuming Li, Yimeng Hao 
    Abstract: A numerical study on the flame diffusion characteristics was effectuated in one aero-engine nacelle. A non-ventilated physical model was established with both inlet and outlet in open condition. A calculated model was constructed by means of the fire classical software based on LES method. Twelve detectors were placed along the horizontal and tangential directions to trace the variations of the flame characteristic parameters such as temperature, pressure, and velocity together with component concentrations. The results show that the non-premixed flame characteristic parameters undergo both the transient and steady states. In the transient state, most of those thermal and chemical parameters such as temperature, velocity, and oxygen together with soot concentrations evidently change (increase or reduce). Those parameters increase along the inner cylinder in the left part of the nacelle, however they vary in an opposite manner. Those parameters are more evidently in the detectors located at the lower and upper ends of the nacelle than those in other detectors elsewhere. The pressure variation is not evidently in the nacelle due to the inlet and outlet in the open condition. In the steady state, the distributions of those parameters are always quasi-symmetrical. The calculated results may provide reference in the firewall design and its structural optimisation.
    Keywords: engine nacelle; FDS; diffused flame; temperature; velocity; soot concentration.

  • Role of Earth bulge on the prediction of radio propagation path loss over irregular terrain   Order a copy of this article
    by Yashu Shankar, D.K. Lobiyal 
    Abstract: In this paper, we have proposed a new approach for the prediction of path loss for mobile radio waves over irregular terrain based on the impact of Earth bulge under different weather conditions. Earth bulge represents the circular segment or the curvature of the Earth. As the weather changes, the value of Earth bulge also varies. Different values of Earth bulge are used according to the weather conditions from normal to worst. These values of Earth bulge are used to compute actual distance in terms of geometric distance to the radio horizon between the transmitting and receiving points. The path loss is computed for this actual distance using the two-ray ground reflection model. The results obtained for the path loss over actual distance for different weather conditions is compared with the corresponding path loss measurement data available for the existing terrain scenarios. The comparative results show the better agreement of the path loss measurement for the given scenarios with the path loss obtained under normal condition than the path loss obtained under other conditions. Also, data analysis from the comparative results shows that the mean error for normal weather condition is smaller than the mean error for other conditions.
    Keywords: radio horizon; irregular terrain modelling; path loss; Earth bulge; two-ray ground reflection model; radio propagation.

  • Overload control in SIP signalling networks with redirect servers   Order a copy of this article
    by Kiran Kumar Guduru, Usha Jayadevappa 
    Abstract: Session Initiation Protocol (SIP) is the most popular IP based application level signalling protocol used for managing multimedia sessions and chat sessions between two or more users. Exponential growth in the usage of smartphones has spurred the use of IP based multimedia communications. Rapid growth in the usage of internet telephony is increasing the load on servers resulting in server overload. Overload control techniques for SIP servers were proposed and standardised; however, existing SIP signalling networks with redirect servers are not well equipped to handle overload conditions. This research work discusses the limitations of existing SIP overload control techniques when employing redirect servers and proposes a solution for controlling overload in downstream SIP servers when employing redirect servers. We proposed an algorithm for controlling overload state and formulated the condition for analysing the overload control parameters, based on queue lengths. Simulation studies revealed that retransmissions in the proposed system are reduced by 63.64% and that of throughput is increased by 27.39%. Call failure rate is reduced by 0.5%.
    Keywords: session initiation protocol; SIP redirect servers; SIP overload control; SIP transactions; retransmissions.

  • Magnetic-field antenna for mobile reception of horizontally polarised television-band signals   Order a copy of this article
    by Kent Chamberlin, Benjamin McMahon 
    Abstract: This paper addresses a solution for an unmet need in the off-the-shelf antenna market. That unmet need is for a low-cost, wideband, VHF/UHF and horizontally polarised antenna that is suitable for mounting on vehicles. The solution that is described here is a magnetic field antenna that performs in the bands of interest as a result of high-frequency magnetic materials. Although this antenna is not yet available commercially, it can be fabricated using readily available materials. Comparison data are presented that show that the magnetic-field antenna has reception characteristics very similar to currently available antennas, although it is far better suited for mobile applications.
    Keywords: magnetic-field antenna; H-field antenna; Hertzian dipole; DTV antenna; datacasting; isotropic horizontal polarisation antenna; electrically small broadband antenna.

  • A novel multiuser detection based on honey bees mating optimisation and tabu search algorithm for SDMA-OFDM systems   Order a copy of this article
    by Imane Chiali, Fatima Debbat, Fethi Tarik Bendimerad 
    Abstract: In the wireless communication systems, the classic multiuser detection (MUD) techniques such as the minimum mean square error (MMSE) detector have some limitations and imperfections owing to multi-access interference (MAI), especially in an overloaded scenario when the number of users is more than the number of receiving antennas. The optimal maximum likelihood (ML) detector gives an excellent result to estimate the transmitted data but suffers from a computational complexity that grows exponentially with the number of users. In this paper, we propose a new metaheuristic approach for multiuser detection based on honey bees mating optimisation (HBMO) hybridised with tabu search (TS) for an uplink space division multiple access orthogonal frequency division multiplexing (SDMA-OFDM) system in a flat Rayleigh fading channel. Indeed, the HBMO algorithm provides a good estimation for TS while exploring the largest regions, while the TS algorithm uses this estimation to find the best solution of the problem. The simulation results show that the proposed algorithm HBMO-TS-MUD provides the best trade-off between performance and computational complexity compared with conventional detectors and the other MUD detectors proposed as genetic algorithm hybridised with the tabu search (GA-TS).
    Keywords: multi-input-multi-output; space division multiple access; orthogonal frequency division multiplexing; multiuser detection; honey bees mating optimisation; tabu search.

  • Trajectory tracking of 4-DOF assembly robot based on quantification factor and proportionality factor self-tuning fuzzy PID control   Order a copy of this article
    by Cuiqiao Li, Ying Sun, Gongfa Li, Du Jiang, Haoyi Zhao, Guozhang Jiang 
    Abstract: When the manipulator performs the assembling task, it has higher requirements for motion stability and control accuracy. However, the performance of the manipulator system is easily affected by external interference and parameter changes, resulting in slow tracking response speed and low tracking accuracy. In order to improve the stability and robustness of the controller, a self-tuning fuzzy PID controller with quantification factor and proportionality factor is designed based on fuzzy PID control. The parameters of the PID controller are dynamically fine-tuned by the fuzzy controller 1, and the quantification factor and proportionality factor are adjusted online by the modifying fuzzy controller 2 to fine-tune the parameters of the PID controller. In order to verify the control effect and the robustness of the improved fuzzy-PID controller for the manipulator system, the simulation is carried out on the platform of MATLAB/Simulink. The simulation results show that the proposed method significantly improves the transient response speed, tracking accuracy and follower characteristics of the system. And it has good dynamic performance and optimal control effect.
    Keywords: assembly manipulator; trajectory tracking; quantification factor; proportionality factor; fuzzy PID control.

  • Control of congestion and traffic lights using intelligent approaches in smart city   Order a copy of this article
    by Mamata Rath, Bibudhendu Pati, Chhabi Rani Panigrahi, Sheng-Lung Peng 
    Abstract: Smart traffic regulation is a major challenge for the engineers of smart applications in smart urban areas. Regardless of many smart applications such difficulties have not yet been completely comprehended because of an assortment of unpredicted traffic situations in various areas and also the necessity of progressive choice-taking parameters. Because traffic congestion focuses individuals, in significant metropolitan urban communities are confronting such issues. This causes unforeseen delays to travel, and the odds of accidents are increased, pointless fuel use is an issue, and unhygienic conditions because of pollution additionally affect the wellbeing of individuals in a typical city situation.
    Keywords: smart city; traffic control system; congestion control; safety travel; intelligent traffic system.

  • A novel system model for detecting primary user emulation attack in cognitive radio networks   Order a copy of this article
    by Thulasimani Lakshmanan, A. Hyils Sharon Magdalene 
    Abstract: The recent advances in wireless communication have led to the problem of growing spectrum scarcity. The available wireless spectrum has become scarcer owing to increasing spectrum demand for new wireless applications. A large portion of the allocated spectrum is used only sporadically, leading to underuse of a significant amount of spectrum. To improve the spectrum efficiency, the idea of cognitive radio technology was introduced. This concept provides a promising solution for the spectrum scarcity issues in wireless networks. Meanwhile, the security issues of cognitive radio have received more attention recently since the inherent properties of CR networks would pose new challenges to wireless communications. In this paper, the performances for primary user emulation attacks are studied from the Neyman-Pearson criterion point of view. A novel system model with different configurations of the primary users has been proposed and studied. The experimental results demonstrate the statistical characteristics of the probability of false alarm and missed detection in the proposed system.
    Keywords: cognitive radio; primary user emulation; Neyman-Pearson criterion.

  • Enhanced path-finding process and reduction of packet droppings in mobile ad-hoc networks   Order a copy of this article
    by V. Lakshman Narayana, A. Peda Gopi, D. Anveshini, G.V. Vidya Lakshmi 
    Abstract: Owing to the expansion of mobile communications, the amount of centre points in the Mobile Ad-hoc Networks (MANETs) must be extended. As MANETs are dynamic in nature, there are issues in choosing the best course for bundles. The bundles may defy excess development and stop up in the framework, which degrades the execution of general framework and affects these issues and may even cause packet droppings. This paper proposes another coordinating approach that strengthens the properties of both static and dynamic guiding traditions and tries to take out the issues natural in the framework through thickness-based coordination. The paper focuses on a productive course revelation process for secure information exchange with less proportion of bundle loss. The examination for the most part focuses on the typical development of the framework and in the wake of separating it the packet is given a path from source to objective that is less congested. For the minimisation of strike and packet dropping, diverse makers produced distinctive systems, such as the technique of centre point approval, reserved feedback contrive, ACK-based strategy, status-based arrangement and persuading power subordinate arrangement, ACK-based arrangement persevered through an issue of massive overhead on account of extra certification bundle and it, in like manner, persevered through decision dubiousness if requested centre point decrease to send back Acknowledgment. In this paper, the proposed method uses a 2-ACK-based arrangement with a secured channel for overcoming the issue of decision obscurity for requested centre point, improved centre affirmation and cutoff bundle dropping in ad-hoc orchestration.
    Keywords: MANET; congestion analysis; dynamic routing; packet dropping diminution; 2-ACK technique.

  • A priority and path diversity-based approach for media streaming over multi-hop and unreliable networks   Order a copy of this article
    by Mohamed Hassan, Dana Hussein, Tamer Shanableh 
    Abstract: Despite the recent advances, media streaming over multi-hop unreliable networks, such as the Internet and wireless packet networks, is still challenging because of the dynamic and unpredictable nature of these networks. This paper proposes an approach that exploits paths redundancies offered by multi-hop networks along with the differential sensitivity inherent in the encoded video information to enhance the quality of experience of video viewers in terms of the continuity of video playback, without compromising the quality of the reconstructed video. The performance of the proposed priority-and-path diversity-based (PPD) video transmission scheme is compared through simulations with a best effort streaming model that mimics todays Internet as well as a priority-based queuing streaming model that can be used in multi-hop wireless networks. The simulation results show that the proposed PPD streaming model outperforms the other two streaming models not only in the achieved video quality, as represented by the average peak signal to noise ratio, but also in terms of the average end-to-end delay and losses which are reflected by the instantaneous occupancy of the playback buffer at the viewer side.
    Keywords: video streaming; path diversity; priority queuing; congestion; quality of service; best-effort networks; multi-hop.

  • Research on financial risk control of rural e-commerce   Order a copy of this article
    by Xiu Yan Bai 
    Abstract: Internet finance has the characteristics of low transaction cost, efficient and fast transaction process, wide coverage, large data value and information sharing. It is difficult for credit information caused by information asymmetry in rural finance, and financial institutions have high operating costs and high risks. The problems of high user financing threshold and low level of user financial information culture are just complementary. Many companies such as Ali and Baidu have launched internet finance businesses. The core of internet finance is risk control, by collecting user information for data analysis, evaluating user credit ratings, identifying fraudulent users, increasing fraud costs for fraudulent users, and blocking fraudulent users before lending to prevent risk.
    Keywords: rural e-commerce; internet finance; risk control.

  • Study on carbon footprint model and its parameter optimisation of wave soldering process based on response surface method   Order a copy of this article
    by Renwang Li, Haixia Liu, Jiaqi Li, Jinyu Song, Rong Jie 
    Abstract: In order to respond to low carbon manufacturing, from energy, materials and process carbon emissions, etc., this paper constructs a carbon footprint model for the wave soldering process in the module workshop of H Company. Based on this model, the carbon footprint value of the wave soldering process is calculated. On the basis of selecting appropriate parameter factors, a parameter optimisation model of the wave soldering process life-cycle carbon footprint is constructed, and the optimum parameters combination is analysed by the response surface method, which contains surface area, clip velocity, clipping angle, flux flux, purity of solder, temperature of tin furnace, height of wave peak, etc. The the response values obtained are verified. The experimental results show that the optimised parameters are used to process and manufacture the wave soldering process, and the carbon emissions produced by wave wave welding can be controlled from above 15 kg CO2 to 12 kg CO2.
    Keywords: wave soldering; carbon footprint; calculation model; response surface method; parameter optimisation.

  • Enhancing uplink/downlink performance of massive MIMO system using time-shifted pilot signal transmission with pilot hopping   Order a copy of this article
    by Amrita Ruperee, Shikha Nema 
    Abstract: In a massive Multiple Input Multiple Output (MIMO) system, pilot signals are reused to accommodate an exponential rise in user density. This contaminates the channel estimation for the intended user and affects the system performance. In the proposed time-shifted pilot signal transmission with pilot hopping (TSPTPH) system, pilot signal transmission is overlapped with downlink data transmission and pilot signal hopping is performed in each coherence interval. Hopping is achieved by switching the user to a new pilot signal, which results in random change in interfering users. This changes the large-scale fading coefficient beta, which is a function of radial distance between base station and user, and thus improves the system performance. The proposed system enhances the uplink and downlink signal to interference plus noise ratio and data rate by estimating the channel with minimum mean square error estimation and reduces the uplink signal to noise ratio for data transmission for normalised spectral efficiency with rising number of antennas at the base station.
    Keywords: channel estimation; pilot hopping; large-scale fading; pilot contamination; pilot sequence; small-scale fading; transmission slot.

  • Average secrecy rate and probability of non-zero secrecy capacity of wiretap generalised gamma fading channels   Order a copy of this article
    by Sudakar Chauhan, Anshul Singh, Sandeep Singh, Avinash Singh, Gaurav Verma 
    Abstract: In this paper, secrecy performance is studied for the classic Wyners wiretap channel which follows the Generalised Gamma (GG) distribution. In order to evaluate the secrecy performance, we derived the exact average secrecy rate and closed form expression for the probability of non-zero secrecy capacity for different fading parameters corresponding to main and eavesdroppers channel. The results are then simulated and verified.
    Keywords: average secrecy rate; physical layer security; probability of non-zero secrecy capacity; generalised gamma distribution.

  • An enhanced multilevel ML-DFT codebook algorithm for hybrid beamforming of millimetre wave MIMO systems   Order a copy of this article
    by Isa H. Altoobchi, Mohab Mangoud 
    Abstract: Millimetre Wave (mmWave) wireless communications is considered an enabling technology to allow fifth generation (5G) cellular networks to achieve extra high-speed data rates. Large-scale antenna arrays can be adopted at the transceiver to compensate the huge path loss due to small wavelength at higher frequencies. mmWave MIMO precoding cannot be performed only at baseband owing to high cost and high-power consumption of signal mixers and analog-to-digital converters (ADCs). Therefore, hybrid analog-digital architecture at transceiver is considered as a cost-effective precoding scheme. However, the optimal design of such hybrid precoders and combiners for practical mmWave transceivers needs to be further investigated. In this paper, a maximum likelihood (ML) beamforming technique is used for estimating the signals direction of departure (DoD) in the presence of random noise. Moreover, an enhanced low-cost Orthogonal Mapping based Matching Pursuit (OBMP) algorithm is proposed. Predefined layered radio frequency orthogonal codebook is used to adjust base stations beamformers for providing more accurate transmitters. Simulation results demonstrate that the proposed hybrid precoder provides acceptable performance gain with almost 90% of the performance of optimal full-digital precoder with great reduced complexity.
    Keywords: millimetre wave MIMO; maximum likelihood; beamforming; radio frequency codebook.

  • Demand response capacity constrained optimisation of multicast routing in smart grid   Order a copy of this article
    by Zihao Zhu, Xiaohui Li, Yuemin Ding, Zhenxing Liu 
    Abstract: Smart grid provides power grid users with a stable and economical power transmission network by demand response (DR). DR operation performed in very short delay can make the smart grid more reliable in the context of smart grid wide area control. Multicast-based communications are a feasible choice for reducing DR communication delay. Traditional multicast algorithms that only consider constraints such as bandwidth or delay will result in a large delay of DR command transmission to the users with large DR capacities far from the control centre, while the users with large DR capacities need more time to perform DR operations. This results in an increase in the amplitude and regulation time of the power grid frequency. In order to solve this problem, this paper presents an algorithm that views DR communication delay and DR capacity as constraints, namely minimum Bandwidth Tree with delay and DR capacity constraint (BTDR), to construct multicast communication for DR commands. It introduces the DR capacity of the target node into the indication function. By indication function, BTDR uses the greedy algorithm to enable the node with large DR capacity to connect to the multicast tree with high priority in the process of constructing the multicast tree, reducing the response time of the DR device with large DR capacity. The simulation results show that the algorithm effectively reduces the frequency fluctuation of the grid, improves the stability of the grid, providing a regulation service for stabilising the power quality.
    Keywords: smart grid; multicast routing algorithm; demand response; low latency.

  • Speech emotion recognition of mobile application based on Chebyshev-PCA optimization   Order a copy of this article
    by Guohua Hu, Xiaoxia Zheng, Qingshan Zhao 
    Abstract: In the application of mobile communication, speech communication is direct and convenient, but the speech information in the mobile scene is easily disturbed by noise. Therefore, in order to solve the problem of speech noise interference in mobile applications, the combination of speech noise reduction and feature dimensionality reduction is proposed to improve the emotional recognition performance of emotional features to noisy speech. Firstly, three kinds of common emotion (sad, happy and neutral) in Berlin speech database and CASIA corpus were selected to add noise and extract the emotional features of noisy speech. Secondly, the Chebyshev filter was used to filter the noisy signals, and principal component analysis (PCA) was used to extract the emotional features of the speech after noise reduction. Finally, in order to analyse the effect of speech features processed by Chebyshev-PCA on emotion recognition, the effect of emotion recognition was compared with that of emotional features after denoising by the Chebyshev filter and extracting noisy signal features by PCA. The experimental results show that the emotional features processed by Chebyshev-PCA can represent the emotional information more accurately.
    Keywords: speech emotion recognition; Chebyshev filter; principal component analysis.

  • Evaluation of planar inclination error measurement uncertainty   Order a copy of this article
    by Ke Zhang, Guo Cheng, Siyuan Liu 
    Abstract: In order to realise the uncertainty evaluation of the inclination error, an error evaluation method and uncertainty of the inclination were investigated based on the Coordinate Measuring Machine (CMM). First, the measured line and datum line were measured. Then, the inclination error was evaluated according to an improved Particle Swarm Optimisation (IPSO) algorithm. Finally, based on the results of the inclination error, the uncertainty was evaluated by applying the GUM method (GUMM) and Monte Carlo method (MCM). The results show the IPSO optimisation algorithm and MCM both provide better accuracy and efficiency on inclination errors and uncertainty evaluation.
    Keywords: inclination error; uncertainty analysis; IPSO algorithm; GUMM; MCM.

  • Water leakage detection and localisation based on GCC-PHAT algorithm   Order a copy of this article
    by Yuting Liu 
    Abstract: Detection and localisation of pipeline leakage is an effective measure to save water resources. The generalised cross-correlation algorithm is widely used in leak detection. In this paper, by comparing the weighted algorithms of generalised cross-correlation functions, the GCC-PHAT algorithm is used to design a leak detection and positioning system, and relevant experiments are carried out. Multiple sensors are used (including flow meters, pressure gauges and vibration sensors) to detect leaks and obtain relevant data in the experiment and locate the leak point through the GCC-PHAT algorithm. It is found that the method has better positioning performance through experiments.
    Keywords: water leakage; detection; localisation; GCC-PHAT algorithm.

  • Diffusion features of aviation fuel fire in one obstructed nacelle   Order a copy of this article
    by Yu Zheng, Guanbing Cheng 
    Abstract: The accessory gearbox (AGB) and the electric engine control (EEC) are the important assemblies to keep the aircraft and its powerplant in good operational condition. The engine nacelle encases AGB, EEC and other devices. The leaked aviation fuel fire encounters with hot spots or high temperature zone and leads to the seriously unsafe scenarios. In present paper, the physical and calculated models of one nacelle laden with AGB and EEC were constructed. Four slices were placed to trace the thermal (temperature and pressure), kinetic (velocity) and physiochemical (oxygen, soot and CO concentrations) parameters nephograms in the nacelle. The effects of AGB and EEC were examined on the non-premixed flame diffusion properties. The numerical results show that those thermal, kinetic and physiochemical parameters undergo the transient and steady states. The effects of AGB on those parameters are more evident than those of the EEC because the AGBs height is larger. In the transient state, the temperature, velocity, and soot or CO concentrations increase originally and oscillate around a constant. As for the flame pressure, it seems to keep constant. To some extent, the AGB prevents the diffused flame from propagating along the nacelle surfaces. However those parameters distributions still take on a quasi-symmetrical structure under the influence of the EEC. The presences of AGB and EEC amplify the oscillation of those parameters.
    Keywords: engine obstructed nacelle; FDS; diffused flame; temperature; velocity; species’ concentration.

  • Secure co-operative neighbour based approach for detection and prevention of black hole attack in wireless mobile ad hoc networks   Order a copy of this article
    by Suyash Bhardwaj, Vivek Kumar 
    Abstract: Mobile ad hoc networks are infrastructure-less, temporary networks that are exposed to routing attacks. Black hole attack is a routing attack formed by dropping all the received packets by a malicious node. To ensure the security and strength of MANETs a secure and effective mechanism is obligatory.
    Keywords: MANET; AODV; black hole attack; cooperative neighbour based detection mechanism.

  • A new objective function for RPL routing protocol in IoT to increase network lifetime   Order a copy of this article
    by Seywan Moradi, Reza Javidan 
    Abstract: Internet of Things (IoT) as the next generation of networks, provides wide virtual environment to connect smart devices through a large network. IoT uses Routing Protocol of Low Power and Lossy Networks (RPL) for routing task. RPL employs an Objective Function (OF) that precisely defines metrics to determine the next hop of nodes with calculation of path cost. Energy imbalance between nodes is considered as one of the main problems in RPL, which causes a substantial increase in energy consumption. In this paper, we design a new OF called Time Objective Function (T-OF) to achieve balance between energy of the nodes to improve network lifetime. It uses not only energy consumption and Expected Transmission Count (ETX) metrics, but also a new metric named Number of Children and Siblings (NOCS), which results in selection of the parents in order to minimise the number of children and siblings. Besides, a weight of metrics will change during network lifetime. Finally, our proposed T-OF has been compared with Minimum Rank with Hysteresis Objective Function (MRHOF), Objective Function Zero (OF0), and Energy Objective Function (EN-OF). Experimental results show that the proposed OF improves network lifetime and energy balancing significantly due to lower delay, 11.35 seconds, and Packet Delivery Ratio (PDR) of 95%.
    Keywords: RPL; objective function; energy balancing; network lifetime; number of children and Siblings; NOCS; IoT.

  • Optimise financial cost for smart agriculture based on genetic algorithm   Order a copy of this article
    by Xu Gaofeng 
    Abstract: Smart agriculture is an emerging application which is largely based on the internet of things. An intelligent agricultural system contains several components, such as the upper layer, an agricultural expert system, and the lower layer, a wireless device network. In a kind of common wireless sensor network, the time-serials data sensed by wireless sensor nodes is delivered by hop-hop communication. Sensor nodes cannot broadcast the sensed data to the base station directly, but can through the help of neighbour nodes. The hop-hop delivery can simplify the framework of the wireless sensor network for smart agriculture, which no longer needs multiple layers or cluster in the network. And this simple type of wireless sensor network can also work well without the help of mobile devices and UAV which are very expensive and import more financial cost. The energy cost generated by the hop-hop delivery can be greatly reduced with the optimisation of the path covering all greenhouses. Minimising the time cost and energy cost with a genetic algorithm can largely decrease the investment cost, which will further make smart agriculture more suitable for financial investment.
    Keywords: financial cost; hop-hop network; smart agriculture; genetic algorithm.

  • Research on vehicle weld clearance detection algorithm based on image processing   Order a copy of this article
    by Xiaoli Zhang, Xiaoyong Han 
    Abstract: The realisation of weld clearance detection algorithm is the key to vehicle weld detection which based on image processing. Based on required high resolution CCD image for vehicle weld clearance, the thesis set the weld detection area in collecting images in the detection of geometrical characteristics of the weld gap and is combined with Hough transform and least squares to detect the weld line. The thesis also optimised the broken line, overlap line, and abnormal linear in the detection of linear and extracted the effective weld line. The research of this method can successfully realise the rapid and accurate measurement of vehicle weld gap.
    Keywords: image processing; weld detection; weld straight line detection.

  • Study on the relationship between occupational wellbeing and stress of young faculties in Chinese universities   Order a copy of this article
    by Shuyuan Zhang, Qiaoyan Yang, Xiaochen Wang 
    Abstract: As the main force of higher education and scientific research, young teachers are stressed in work and life. Study of young teachers sense of occupational wellbeing and stress is of great significance, so as to improve their health physically and mentally, and enhance their working efficiency. Applying the revised scale on sense of occupational wellbeing and stress, this research conducted a survey from 685 young teachers from China with statistical methods of correlation analysis and ANOVA. The result reveals that full-time young teachers are in the moderate level of occupational wellbeing among variables of interpersonal relationship, job satisfaction and organisational support, and they are under tremendous stress in scientific research, teaching and economic position. There is a negative correlation between occupational wellbeing and stress, while stress of promotion and economic position had a larger impact on young teachers sense of occupational wellbeing. There are a significant gender differences in dealing with stress from promotion, economic position and marriage. Teachers with different positional titles vary in their job satisfaction, general sense of wellbeing, and stress from their economic position and marriage. There is a remarkable difference in income for young teachers in all the dimensions who have a sense of occupational wellbeing and stress.
    Keywords: occupational wellbeing; occupational stress; young teacher.

  • A study of an improved RCNN network model for surface defect detection algorithm of precision workpiece and its realisation   Order a copy of this article
    by Xiaohong Dai, Yingji Zhao, Chaoping Zhu 
    Abstract: In this paper, an improved RCNN algorithm for surface defect detection of precision workpiece is proposed. During model training, the original image is processed by data amplification, which overcomes the phenomenon of model overfitting caused by a too small dataset. The fuzzy image is processed by the conditional generation antagonism network, which guarantees the authenticity of the image and eliminates the fuzziness of the image. On the basis of network selection, through network training and comparative analysis, ResNet101 was selected as the basic network for feature extraction. By combining the network performance, the number of convolutional layers (model depth), system efficiency and other factors, and taking advantage of the spatial characteristics of images, the irregular cross-convolution kernel idea and the differentiated convolution kernel design method are adopted to realise the feature fusion of different convolutional layers, embedded in the target Network SE (Squeeze and Excitation module) channel features fusion module, the FPN (Feature Pyramid Network) module, and the ROI Network module. The experimental results show that the improved network model is used to realise the location and classification of defects on the workpiece surface, The detection accuracy was 91% and the recall rate was 93%.
    Keywords: precision workpiece; defect identification; convolution neural network; deep learning; target detection.

  • Design of integrated fire alarm system for integrated pipe gallery based on multi-environmental sensors   Order a copy of this article
    by Wei Liming, Guo Xing, Wang Qiucui 
    Abstract: This paper designs a fire warning system for the purpose of preventing unsafe accidents such as fires in integrated pipe corridors. The sensor is used to monitor the internal environmental parameters of the pipe gallery, and the combination of PLC and Labview software is used to design the overall scheme of the system. The upper computer interface and the system operation framework are given, and the selection process of the lower computer and the simulation process of the upper computer are explained. The designed system can prevent to some extent the early stage of the fire by earlier control of the fire hazard in the pipe gallery from the source to provide a guarantee for the safe operation of the integrated pipe gallery.
    Keywords: pipe corridor fire warning; sensor; PLC; host computer simulation.