Comparison and analysis of eight scheduling heuristics for the optimization of energy consumption and makespan in large-scale distributed systems

In this paper, we study the problem of scheduling tasks on a distributed system, with the aim to simultaneously minimize energy consumption and makespan subject to the deadline constraints and the tasks’ memory requirements. A total of eight heuristics are introduced to solve the task scheduling problem. The set of heuristics include six greedy algorithms and two naturally inspired genetic algorithms. The heuristics are extensively simulated and compared using an simulation test-bed that utilizes a wide range of task heterogeneity and a variety of problem sizes. When evaluating the heuristics, we analyze the energy consumption, makespan, and execution time of each heuristic. The main benefit of this study is to allow readers to select an appropriate heuristic for a given scenario.     

Mosaic-Net: a game theoretical method for selection and allocation of replicas in ad hoc networks

Due to the continuous mobility of hosts, an ad hoc network suffers from frequent disconnections. This phenomenon is undesirable when mobile hosts are accessing data from each other, and thus, data accessibility is lower than that in conventional fixed networks. Because one cannot control network disconnections, an alternative solution to this problem is to replicate data objects onto mobile hosts so that when disconnections occur, mobile hosts can still access data. In this paper, a mathematical model for data object replication in ad hoc networks is formulated. The derived model is general, flexible and adaptable to cater for various applications in ad hoc networks. We prove that this problem in general is NP-complete and propose a game theoretical technique in which players (mobile hosts) continuously compete in a non-cooperative environment to improve data accessibility by replicating data objects. The technique incorporates the access frequency from mobile hosts to each data object, the status of the network connectivity, and communication costs. In the proposed scheme, players (mobile hosts) compete through bids in a non-cooperative environment to replicate data objects that are beneficial to themselves and the system as a whole. To cater for the possibility of cartel type behavior of the players, the scheme uses the Vickrey payment protocol that leaves the players with no option than to bid in such a fashion that is beneficial to the system as a whole. The paper also identifies some useful properties of the proposed scheme and the necessary conditions of optimality. The proposed technique is extensively evaluated against some well-known ad hoc network replica allocation methods, such as: (a) randomized, (b) extended static access frequency, (c) extended dynamic access frequency and neighborhood, and (d) extended dynamic connectivity grouping. The experimental results reveal that the proposed approach outperforms the four techniques in solution quality and projects a competitive execution time.     

New multi‐standard dual‐wideband and quad‐wideband asymmetric step impedance resonator filters with wide stop band restriction

New multi‐standard wide band filters with compact sizes are designed for wireless communication devices. The proposed structures realize dual‐wideband and quad‐wideband characteristics by using a new skew‐symmetrical coupled pair of asymmetric stepped impedance resonators, combined with other structures. The first and second dual‐wideband filters realize fractional bandwidths (FBW) of 43.2%/31.9% at the central frequencies (CF) of 1.875/1.63 GHz, and second bandwidths of 580 MHz/1.75 GHz at CF of 5.52/4.46 GHz, respectively. The proposed quad‐band filter realizes its first/second/third/fourth pass bands at CF 2.13/5.25/7.685/9.31 GHz with FBW of 46.0%/11.4%/4.6% and 5.4%, respectively. The wide pass bands are attributed to the mutual coupling of the modified ASIR resonators and their bandwidths are controllable by tuning relative parameters while the wide stop band performance is optimized by the novel interdigital cross coupled line structure and parallel uncoupled microstrip line structure. Moreover, the quad band is generated by introducing the novel defected rectangle structure. These multi‐standard filters are simulated, fabricated and measured, and measured results agree well with both simulated results and theory predictions. The good in‐band and out‐of‐band performances, the miniaturized sizes and simple structures of the proposed filters make them very promising for applications in future multi‐standard wireless communication.     

AMA: a new approach for solving constrained real-valued optimization problems

Memetic algorithms (MA) have recently been applied successfully to solve decision and optimization problems. However, selecting a suitable local search technique remains a critical issue of MA, as this significantly affects the performance of the algorithms. This paper presents a new agent based memetic algorithm (AMA) for solving constrained real-valued optimization problems, where the agents have the ability to independently select a suitable local search technique (LST) from our designed set. Each agent represents a candidate solution of the optimization problem and tries to improve its solution through co-operation with other agents. Evolutionary operators consist of only crossover and one of the self-adaptively selected LSTs. The performance of the proposed algorithm is tested on five new benchmark problems along with 13 existing well-known problems, and the experimental results show convincing performance.     

Reliable control design for composite‐driven scheme based on delay networked T‐S fuzzy system

This paper is focused on reliable controller design for a composite‐driven scheme of networked control systems via Takagi‐Sugeno fuzzy model with probabilistic actuator fault under time‐varying delay. The proposed scheme is distinguished from the other schemes as mentioned in this paper. Aims of this article are to solve the control problem by considering the H_∞, dissipative, and L₂?L_∞ constraints in a unified way. Firstly, to improve the efficient utilization of bandwidth, the adaptive composite‐driven scheme is introduced. In such a scenario, the channel transmission mechanism can be adjusted between adaptive event‐triggered generator scheme and time‐driven scheme. In this study, the threshold is dependent on a new adaptive law, which can be obtained online rather than a predefined constant. With a constant threshold, it is difficult to get the variation of the system. Secondly, a novel fuzzy Lyapunov‐Krasovskii functional is constructed to design the fuzzy controller, and delay‐dependent conditions for stability and performance analysis of the control system are obtained. Then, LMI‐based conditions for the existence of the desired fuzzy controller are presented. Finally, an inverted pendulum that is controlled through the channel is provided to illustrate the effectiveness of the proposed method.     

Greatly reduced leakage current and defect mechanism in atmosphere sintered BiFeO3–BaTiO3 high temperature piezoceramics

In current work, the effect of sintering atmospheres (N₂, air and O₂) on the structure, electrical properties, and defect mechanism of 0.8BiFeO₃–0.2BaTiO₃ lead-free piezoelectric ceramics has been investigated. X-ray diffractometer results indicated all the samples crystallized into the rhombohedrally distorted perovskite structure which was independent on the sintering atmospheres. Bi-containing impurity phases were observed in N₂ sintered samples while not appearing in other atmospheres. X-ray photoelectron spectrum analysis indicated more Fe²⁺ ions, which can result in high leakage current, were involved in N₂ sintered ceramics than that in O₂- and air sintered compositions. However, greatly reduced leakage currents were obtained in N₂ sintered ceramics which should be ascribed to the formation of secondary phases. The largest polarization and lowest leakage current were obtained in the sample sintered in N₂ (2 h), which owned the optimal ferroelectric, piezoelectric, and electromechanical properties with piezoelectric constant d ₃₃ = 98 pC/N, planar electromechanical coupling factors k _p = 26.1 %, remnant polarization P _r = 25.7 µC/cm², coercive field E _c = 74.6 kV/cm, and a high Curie temperature T _c = 632 °C, respectively.     

Wireless Body Area Sensor Network Authentication Using Voronoi Diagram of Retinal Vascular Pattern

This paper focuses on the problem of human authentication in Body Area Sensor Network using retina. In this proposed method, Voronoi Diagram (VD), a well known technique in computational geometry, is generated from the topological structure of the bifurcation points, considered as vertices, obtained from the blood vessels found in the retina which can further be used in the process of identification and verification. Since the structure formed by bifurcation points is unique in every retina, hence the calculated VD is also unique and provides the foundation of developing the system of retina based identification. The approach presented in this paper rejects any non-similar retina instantly while maintaining excellent accuracy and performance. Another advantage of using this approach is that it does not require the localization of Optic Disc and the Fovea, which most of the existing algorithms have required, and, experimental results proved that VD is efficient in template matching and storage requirements. Additionally, our proposed algorithm is invariant against any geometric transformation (i.e. scaling, translation and rotation).     

Hydromagnetic nanofluid flow past a stretching cylinder embedded in non-Darcian Forchheimer porous media

The present article presents the hydromagnetic nanofluid flow past a stretching cylinder embedded in non-Darcian Forchheimer porous media by using Buongiorno’s mathematical model (Buongiorno in J Heat Transf 128:240–250, 2006; Nadeem et al. in J Taiwan Inst Chem Eng 45:121, 2014, Nadeem et al. Appl Nanosci 4:625–631, 2014). Thermal radiation via Roseland’s approximation (Akbar et al. in Chin J Aeronaut 26:1389–1397, 2013; Nadeem and Haq in J Aerosp Eng 28:04014061, 2012), Brownian motion, thermophoresis and Joule heating effects are also considered. To explore thermal characteristics, prescribed heat flux and prescribed mass flux boundary conditions are deployed. Governing flow problem consists of PDEs in the cylindrical form, which are converted into system of nonlinear ODEs by applying applicable similarity transforms. ODEs are tackled by RK–Fehlberg fourth–fifth-order numerical integration scheme with shooting algorithm. Impact of numerous involving physical parameters on flow features like temperature distribution, velocity distribution, Sherwood number, local Nusselt number and skin friction coefficient is shown through graphs and tables.