Earticle

This paper proposed an improved particle swarm optimization positioning algorithm based on virtual force-directed method for node localization of wireless sensor networks. The improved algorithm adopted adaptive inertia weight and adaptive mutation operation on global optimum, which overcomes the disadvantage of traditional particle swarm optimization algorithm that is easy to be trapped in local optimum. Fast convergence to near optimal solutions can be achieved after inertia weight is adjusted to be bigger, and smaller inertia weight can result in high precision solution. Through adaptive mutation on the global optimum, the improved algorithm can jump out of the current search area to maximize the coverage of the network nodes and the convergence speed. Compared with the virtual force-directed particle swarm optimization algorithm, the simulation results indicate that the improved algorithm has the advantages of faster convergence speed, lower energy consumption, higher precision and better stability.

This paper presents a fractional gain-control technique for a digitally controlled oscillator (DCO). The proposed fine-fractional gain-control scheme improves the jitter performance by suppressing the nonlinear effect of a bang-bang digital phase-locked loop (BB-DPLL). In addition, the proposed structure significantly reduces the chip area, because the proposed fractional DCO dithering circuit requires only one accumulator with an N-2-bit width, while conventional topologies require multiple accumulators with N-bit widths. The simulation result shows that the period jitter of the proposed structure (0.83 ps) is three times better than that of a digital PLL based on a conventional second-order sigma-delta modulator (2.58 ps).

The co-design problem of H∞ filter and scheduling strategy for NCS with stochastic nonlinearities and multiplicative noises is addressed in this paper. With consideration of communication constraints, the NCS are first modeled as a set of discrete-switched subsystems by applying scheduling strategy. Then a novel Lyapunov-Krasovskii functional and delay-partitioning technique are used to design an available filter such that the filtering error system is asymptotically mean-square stable and achieves a prescribed H∞ performance level. A numerical example is given to illustrate the effectiveness of the proposed method.

The Voltage Source Converter based High Voltage Direct Current(VSC-HVDC) is a new generation HVDC technology. Because of the technology of the PWM and the turn-on and turn-off electronic apparatus, VSC-HVDC could make up for the defective of the traditional HVDC. And the development is rapid. This paper introduces some operation principle and summarizes instances. Firstly, the paper introduces the structure and operation principle of VSC-HVDC. Then the paper states the technology characteristic of VSC-HVDC and the application field. In the end of the paper, the paper discusses the situations of the VSC-HVDC in China and other countries.

Renewable energy and energy storage system are a hot topic today since the global warming is related to the burning of fossil fuels. Renewable generations using wind, solar and wave sources are integrated into power system for securing economic feasibility. However, grid-connected wind power having its natural variability greatly may affect stability of power system, and TSO (Transmission System Operator) and ISO (Independent System Operator) have developed grid code for wind power. Especially, technical requirements for testing and simulation are specified in grid code because GCC (Grid Code Compatibility) is ascertained through onsite testing and computer simulation. Therefore, the simulation model requirements should be understood clearly from the early stage of project, and the exact models and reports can be delivered to TSO and certification body on time. Namely, wind turbine manufacturer should deliver its dynamic models, model validation report and test report, on the other hand, wind power plant owner should deliver its dynamic models and commissioning report. The accurate understanding of different simulation model requirements presented from various national grid code avoids simulation modeling error.

The variation ranges of species concentration, temperature and particle concentration of exhaust plume of the diesel engine with different load rate were tested in this article. Based on prototype experiment, the simulated generator and experimental platform of exhaust plume were built, and the effects of temperature, CO2, vapor and carbon soot on the infrared radiation characteristics of the exhaust plume were experimentally studied by infrared imaging. Experimental results showed that the temperature of the exhaust plume was the most important influencing factor for the infrared radiation characteristics, and the CO2 and carbon soot were also important influence factors too. However, the effects of the vapor could be neglected because of the slight influence on the infrared radiation characteristics of the exhaust plume.

A model predictive control method is proposed for the point stabilization of wheeled mobile robots (WMRs) subject to nonholonomic constraints. The problem is simplified by considering only the steering system and neglecting the vehicle dynamics. A linearized error model is then formulated by transforming the robot position into polar frame. The feedback control policy is obtained by minimizing a quadratic cost function which penalizes the predicted errors and control variables in each sampling time over a finite horizon. The proposed control law is proven to guarantee the exponential stability of the robot system by considering additive inequality constraints in the optimization process. The performance of the stabilization algorithm is verified through computer simulations showing that the proposed method has a good regulation performance and convergence.

In this paper the combination rotary sealing of ferrofluid and magnetic grease was used for high power electric motor of certain equipment. The pressure capability and the similar friction power formula of it was derived theoretically, that the viscous dissipation power of magnetic grease sealing is approximate proportional to the (2n 1) th rotational speed. The experiments were carried out to verify the combination rotary sealing was theoretically and experimentally feasible. This structure device has been put into practical use.

This paper proposes a method of fault position detection and location for the axle of railway vehicles, which based on Acoustic Emission technique. The method is used to denoise the Acoustic Emission signal by wavelet transformation and makes signal of continuous processing by Butterworth filter; then finds the maximum in reverse direction after taking threshold comparison with continuous signal in order to form the point of the first peak. Finally fault location is on the basis of the time from the first peak to the sensor. The experimental results indicate that the method can remove interference effectively and its positioning accuracy is better than the location method of Gabor transformation. After all, this method has a great value in engineering application.

This paper designs and develops a wind speed forecast model based on artificial neural networks and voting strategies, aiming at efficiently integrating renewable energies into the power network. The hour-by-hour speed records collected in Jeju city during the past 15 years are classified and converted to create sequential, monthly, and seasonal forecast models, respectively. To predict the next hour speed, the speed records of the previous 5 hours are simultaneously fed to each model first. Then, the voting process picks and averages the two predictions having the best proximity out of 3. The evaluation procedure compares the predicted values and the actual speeds of 2014, which have not been used for training, and finds out that the maximum daily root mean square error for the proposed scheme is smaller than other stand-alone methods by 0.11mps. Moreover, the vote-based scheme avoids the worst case mis-prediction.

A cooling system with high and low temperature double circulations was built. On the basis of analysis of cooling demand of the various components of armored vehicles， the control strategy of the cooling system was designed ，which were based on presetting MAP and fuzzy control. The Coupling Model of the cooling system and the control system was built in Matlab/Simulink software. The simulation results showed the control strategy was effective. Experiments on cooling system test bench validated the control strategy was workable. The research indicate that the control strategy based on presetting MAP and fuzzy control could satisfy the control demand of high and low temperature double circulations cooling system， which at the same time ensure that the temperature of coolant at the outlet of engine block fluctuate no more than 1K，the temperature of low temperature circulation below the set value.

A new strategy on reactive power optimization for power grid with wind farm integration is proposed. The mathematical model is built by using the optimal scenario analysis method and the modified particle swarm optimization algorithm (MPSO). The method about how to obtain the optimal scenarios is discussed. The optimal scenarios position for wind power is deduced based on the Wasserstein distance metric, and the occurrence probability is also studied simultaneously. In order to avoid falling into local optimum, the self-adapting mutagenic factor and mutation probability are designed in MPSO. Simulation examples show the effectiveness of MPSO. The mutagenic factor takes effect when the objective function value tends to be constant. Power loss and voltage stability margin are considered in the objective function. In initial phase of MPSO, the general particle swarm optimization algorithm (PSO) is processed, and this can guarantee the rapid convergence for the optimization procedure. After some iterations, the mutagenic factor begins to have an impact to ensure the global optimum can be obtained. The IEEE 69-bus distribution system is used to the experiment. In the experiment, the optimal scenarios position and scenario occurrence probability are worked out. Test results show that the new strategy is effective.

Two-phase thermosyphons are devices that can transfer large amounts of heat flux with the boiling and condensation of the working fluid resulting from small temperature differences. A two-phase thermosyphon consists of the evaporators, an insulation unit, and the condensers. The working fluid inside the evaporator is evaporated by the heating of the evaporator in the lower part of the two-phase thermosyphon and the evaporated steam rises to the in the upper part to transfer heat in response to the cooling fluid outside the tube. The resultant condensed working fluid flows downward along the inside surface of the tube due to gravity. The resultant condensed working fluid flows downward along the inside surface of the tube due to gravity. These processes form a cycle. In the present study, condensers with various insert devices of a loop type two-phase thermosyphon which is 480mm wide, 68mm long, and 1,000mm high was used. The heat transfer pipes in the loop type two-phase thermosyphon were 15mm in diameter and 1,000mm in length and 98 heat transfer pipes were installed in loop type two-phase thermosyphon. The inside of the condensers with various insert devices was composed of heat transfer pipes installed to increase the heat transfer surface area of the heating media in the heat transfer pipes condensers with various insert devices. Using refrigerant R134a as a working fluid for the loop type two-phase thermosyphon to conduct heat transfer performance experiments for changes in the temperature of the cooling air outside the condenser and changes in the mass flow rate. According to the results of the present experiments, as the spaces between internal discontinuous pins decreased, pressure drops increased. Changes in the temperatures at the outlet of the condenser were shown to be a little smaller. Therefore, it can be seen that as the spaces between internal discontinuous pins decreased, the heat transfer performance increased. As the temperature of the air flowing in the condenser with various insert devices increased, the condensation heat transfer rate of the thermosyphon increased. As the condenser with various insert devices refrigerant inflow temperature increased, the condensation heat transfer rate of the condensers with various insert devices of the thermosyphon heat exchanger increased.

This paper proposes a novel tuning approach for robust proportional-integral-derivative (PID) controller based on H∞ loop shaping synthesis in combination with gap metric and Particle Swarm Optimization (PSO) algorithm. Different from the traditional research, the controller is designed through the search region constrained by H∞ loop shaping synthesis and gap metric theorem. PSO algorithm is used for tuning the robust PID controller parameters based on the underlying constrained optimization problems without resolving complex arithmetical calculations. The control technique is applied for the robust controller design so as to get a low order structured controller and achieve robust performance and the ability of restraining disturbance. The simulation shows that the proposed method can character the set of all values of the controller parameters that guarantees the robust stability with any supposed accuracy and achieves favorable control performance for uncertain systems.

Recently, IETF (Internet Engineering Task Force) presented CoAP (Constrained Application Protocol) for the communication between sensor and actuator nodes in a constrained environment such as small amount of memory and low power. IETF CoAP protocol can convert easily, and can use to monitor or control infrastructure utilities through low-power sensor and actuator networks in IoT (Internet of Things) and M2M (Machine-to-Machine) environment. IETF CoAP protocol provides the special requirements of this constrained environment, especially considering energy, automation, and other IoT applications. In this paper, we design and implement a node registration and discovering based CoAP in IoT environment. The node is a CoAP node which is designed for working in constrained environment. For node registration in IoT, we used CoRE RD (Resource Directory) functionalities to register CoAP node’s information which works in IoT environment.

Under serious conditions, airport will experience temporary shutdown, and while the airport reopen, the controller must make gate reassignment. In order to get intelligent use of the gate resource, the model was studied both considering operational smoothness and passenger satisfaction. The problem was formulated as a binary quadratic programming problem, and then, the model was transferred into dynamic programming (DP) model to solve by transformation, and the complexity of the DP algorithm is analyzed. Later, an improved Tabu Search algorithm (TS) was designed, and the greedy strategies were mixed to speed up the solving speed under large scale problem. At last, numerical simulation results demonstrate the effectiveness of the model and the improved TS algorithm.

The performance of the aero-engine is an important safeguard to flying security. We can diagnose and predict the fault type through obtaining and analyzing the vibration signals based on the fault characters of the aero-engine. But, because of the complexity of the aero-engine’s structure, the vibration signals acquired from multiple groups of the piezoelectric sensors are often composed of several signal aliasing and other noise jamming, etc. Thus, the vibration signals are in the nonlinear or weak nonlinear state, the traditional blind source separation (BSS) algorithms usually adopt linear hypothesis to approximate equivalent to the nonlinear problems, which leading to the separation results not ideal even wrong. This paper applied a kind of multilayer perceptron BP neural network algorithm to realize the aero-engine vibration signal separation with high precision through the simulation and experiment, which proved this algorithm has a certain practical value to the aero-engine fault diagnosis and prediction.

The IP Virtual Private Network technology is increasingly being used due to its efficiency in terms of cost, its availability and its high security level, companies deploy multiple secure tunnels and send through them different traffics, in order to guaranty a reliable level of communication and the availability of resources, many qualities of service’s policies must be defined. According to our research, most of works treat only the problematic of the Quality of Service management in a site to site Virtual Private Network, this was an incentive for us to: design and implement a new model of a smart adaptive quality of service management for the dynamic and multipoint Virtual Private Network, and create a new friendly-user web application to facilitate the quality of service management for such complex networks. This paper discusses a new model for the policy-based management of a smart adaptive quality of service for the Dynamic and Multipoint Virtual Private Network using a new WEB interface.

Vehicle Ad hoc Network are composed of the vehicle with wireless communication equipment, road construction collecting base station transmission network, background processing server and related acquisition and processing software system. Based on Internet of things simulation console, this paper designs vehicle to vehicle scenarios of Intelligent Transportation System, simulates its communication process , analyzes the simulation data of sending and receiving, evaluates the entire performance of the network, which can offer reference to designing and optimizing the Vehicle Ad hoc Network. In this paper we try to prove: In the low speed motion in vehicle to vehicle scenario of Vehicle Ad hoc Network, as the routing protocol in the network layer, AODV protocol is much better than DSR protocol.

Although extensive studies have been done on the protocol conformance testing based on an extended finite state machine (EFSM) model, the automatic generation of feasible test sequences is still a challenging task. A generated test sequence may be infeasible, due to the conflicts among the transition conditions and context variables of EFSMs. This paper proposed a test sequence generation approach for EFSM-based protocols conformance test by using the transition feasibility estimation. Firstly, our method generates candidate transition paths from a directed graph G which is derived from the EFSM model under testing ignoring all the predicates; Then, we designed a fitness function to guide the test generation with a trade-off among path feasibility, coverage criterion and path length. Finally, an adaptive exploration algorithm is developed to generate executable test sequences through expanding CPs. An experiment was designed to validate the effectiveness of the proposed method with two classic EFSM models. The experimental results show that our approach is more effective by comparing it to the TEA method based on breadth-first search (BFS).

The objective of this study was to investigate the cooling performance characteristics of electric-driven air conditioning system using two kinds of coolants with triple fluids heat exchanger for a fuel cell electric vehicle. In order to analyze the cooling performance characteristics, electric-driven air conditioning system with the triple fluids heat exchanger for a fuel cell electric vehicle was developed and tested under various operating conditions according to inlet air conditions of evaporator, coolant conditions and compressor speed. The cooling capacity and coefficient of performance (COP) for cooling of tested air conditioning system were 7.0 kW to 2.8 under high inlet air temperature, 42oC with the rated compressor speed, 5,000rev/min, respectively. In addition, developed triple fluids heat exchanger to transfer heat between a refrigerant and two kinds of coolants was analyzed under the same operating conditions with respect to pressure drop and heat transfer portion among two coolants. The cooling performance and efficiency of the developed electric-driven air conditioning system were thought to sufficient capacity to cope with cooling loads under various real driving conditions for a fuel cell electric vehicle.

The impact of network conditions on routing performance in DTN network has been investigated by means of the simulation experiment. The results show that appropriate number of duplicate messages is a simple and effective policy for store-carry-forward routing design. It performs well in most of the network conditions. It performs well in most of the network conditions in terms of delay, packet delivery ratio and overhead.

A remote sensing image is composed of vegetation and base rock or soil in moutain areas, which can be decomposed by the fractal model through Fourier transformation to enhance base rock or soil information. In this paper, four scene images of two types of bed rock from Anhui province are taken as a case to demonstrate the method’s validity: two scene images’ base rocks are monzonite granite while the other two base rock are limestone and mudstone. The fractal spectrum of the four scene images can’t be distinguished without processing yet the result shows good contrast for the two types of rock. Other contrasts between original and processed images show obvious difference in the two types of image such as in 2D-scatter map, in composed color map. The result proves that the method can improve base rock information in those vegetation covering region.

Skin color segmentation plays an important role in the biological feature recognition system. In order to improve the system adaptability to the complex environment, a new model of Cr*a*b by combing the YCbCr with Lab model is proposed. Firstly, establish the three-dimensional coordinate system based on the Cr, a, b axes, the two-two coordinates form the directional vectors by using the origin as the starting point. Then calculate the angles between the three vectors. Finally, realize the purpose of skin color segmentation by reducing the dimensions of angle data. Experimental results show that this algorithm can improve the over sensitive of YCbCr model to red and yellow, the defect of the skin color weak clustering in the Lab model is also overcame. Even if for the image with complex background environment, the percent of average accurate detection is about 87.7%. The proposed algorithm can get the high skin color segmentation rate and has good practicability.

Light Emitting Diodes (LEDs) are being considered for use in the automobile headlamps for front side illumination in the place of halogen and xenon headlamp systems. Although LEDs provide larger service life and better power efficiency, they generate considerable amount of heat. It is desirable to develop an advanced cooling system to effectively dissipate heat generated for a stable, continuous and reliable LED operation. The objective of this investigation is to experimentally study the factors influencing the cooling performance of the air cooled heat sink model used in an automobile LED headlamp system. The cooling performance of the heat sink model under consideration was assessed by measuring temperature and thermal resistance at significant locations. The input power, fan output and ambient temperature were varied and corresponding effects were observed. The effect of power variation on illuminance was observed. In addition, a comparative study was carried out to determine the effects of forced and natural convection, which indicated the necessity of forced convection for effective cooling of an automobile LED system.

In this paper, a common marine life - octopus is imitated. Based on the research of its tentacles hydrostatic skeletal muscle structure, the propulsive function of the tentacles is strengthened, and a bionic tentacles propulsor driven by shape memory alloy wires is developed. The action experiments show that the propulsor has a simple structure, large flexible deformation and silent action. Using LAEBT to compute tentacle’s average propulsion force, the outcome shows that the tentacle can provide sufficient power. Based on this, a multiple-bionic tentacle propulsor underwater robot is developed. The robot is 230 mm in length, 110 mm in diameter and 590 g in weight. Having discussed the strategy of its motion, a proper one is selected and has been tested. The result of research shows that the robot has reliable structure and seal. It is well friendly to the environment and good at motility. The peak speed is about 115 mm/s while linearly swimming and it can turn at speed of18°/s. This prototype provides a new view on underwater robot developing.

EkadhikenaPurvena is a Sanskrit name which means “one more than the previous”. This technique is used for squaring any big number but the condition is it should end with digit “5”. Vedic mathematical formulas are used to solve tedious and cumbersome arithmetic operations. Tool is Xilinx ISE Design Suite 14.2 and Kintex-7. We have taken different frequencies and calculated its power. Today’s demand forces us to design the low power energy efficient devices which takes lesser time for its execution. In our design there are 2 inputs and 1 output. The inputs are clocked and the number whose square we are supposed to calculate is 8 bits wide and the output is 14 bits wide (squared number). Many researchers have performed research on Vedic mathematics to solve DSP operations using Urdhava-Triyagbhayam multiplication sutra. We have done power analysis by varying frequency at different temperatures to make our Vedic squarer energy efficient. Temperatures taken in view are 56.7, 53.5, 40, 21 degree Celsius and Airflow is 250 LFM (Linear Feet Per Minute). Analysis results shows that the maximum power consumption is at 2.2 Billion Hertz and minimum power consumption is at 1400 Million Hertz. In respect to temperature maximum power is consumed at 56℃ and minimum at 21℃.

The discussion is based on the background of adaptive software development needs according to the application requirements of the mobile terminal. The result, through many scholars' research and development about adaptive software, are analyzed and compared with both the advantages and disadvantages of adaptive software. A development trend of adaptive software design patterns is foreseen. A new feasibility design method is proposed, which is based on adaptive software development model of the combination of design patterns.

Buried water pipe is exposed to excessive ground stress resulting from ground freezing and thawing in low temperature of winter which might lead to the rupture or deformation of water pipe. This paper is intended to identify, through a full scale model test, the ground temperature variation around the buried pipe depending on variation of ambient temperature as well as the displacement of the buried pipe and the stress behavior, and consequently, stress concentration and frost heaving were observed around buried pipe when ground was frozen. And despite of using sandy soil which is considered non-frost susceptible material for the test, frost heaving was occurred depending on water content and drainage condition. Viewing such result, even in case of displacing bedding and backfill material with non-frost heaving material, the countermeasure to protect from frost heaving is necessary depending on surrounding drainage condition, groundwater level and water contents.

In Motion JPEG2000, embedded block coding with optimal (EBCOT) consists of Tier 1 and Tier 2 coding. In Tier 1, every bit-plane is scanned three times and coded in three channels. This means a long operation time, which may account for over 50% of total time of EBCOT. To reduce the time of compression and coding of JPEG2000, it is necessary to study the mechanism of Tier 1 coding, especially in the three-channel scanning mode. It has been found that validity flag  i [j] is the first to be determined in the first and the second scan. If the validity flag is 1, then magnitude refinement (MR) coding is done; if it is 0, we need to determine whether the coding in validity channel is to be done. However, we propose the feasibility of combining the two codings together and perform scanning once. Then we only have to determine whether the coding is to be done for the pixels in the validity channel or in the MR channel. During the first scan, the value of validity flag σi[j] will be determined only once, thus reducing the number of judgments. Therefore, the proposed process of EBCOT consists of 2 scans and coding in 3 channels. This reduces the number of judgment and scans and saves the time.