Earticle

In this paper, the aim was to study Heart Rate Variability during rest and exercise in normobaric hypoxia environment using sample entropy. Sample entropy is a powerful way to analyze non-linear biological system, it’s the first time to analysis hypoxia exercise HRV signal by sample entropy.12 healthy males took part in the experimentation, some of them were asked to stay in the hypoxia cabin for 150 min every day. It’s divided into three 30 min rest periods and three 20 min exercise periods, the rest and exercise period was across. Subjects’ heart rate and SaO2 data were collected. The sample entropy of rest period was compared with exercise period, there’s statistical difference between them. Our results indicate that hypoxia exerts an influence on HRV, it also suggest that acute exposure to normobaric hypoxia induce increases in sympathetic vasomotor activity and cardiac sympathetic dominance result an increased heart rate.

This paper addresses the problem of stability analysis for linear systems with interval time-varying delay. A general form of the delay-fractioning approach is proposed, which not only takes advantage of all possible information on the delay's lower bound, but also exploits further information between the delay's upper and lower bounds. A new Lyapunov-Krasovskii functional (LKF) is constructed and delay-dependent stability criteria are derived in terms of linear matrix inequalities (LMIs) by using the piecewise analysis method. The convexity of the matrix function is used to avoid the conservatism caused by enlarging the time-varying delay to its upper bound in each subinterval. Numerical examples are given finally to verify the effectiveness of the proposed criteria.

The grinding force is a key parameter in the grinding process, which is closely associated with the grinding mechanism of engineering ceramics, microstructure and properties of ceramic materials, and the selection of grinding parameters. Meanwhile, it is also a key indicator to assess the grindability of a material. The grinding force is a crucial parameter to reflect the grinding process, which is closely related with microstructure and properties of the grounded material, grinding parameters, grinding wheel characteristics and material removal mechanism. In this paper, from the perspective of material removal mechanism in ceramic grinding model and the grinding process of engineering ceramics, the ceramics grinding process was analyzed and the formation of grinding force was explored. With the analysis of characteristics of the grinding force, from the aspect of influential factors of the grinding force, impacts of the performance of ceramic materials, grinding direction, grinding wheel velocity, workpiece velocity, grinding depth, particle size of grinding wheel, grinding wheel wearing, the grinding fluid, the rigidity of machine tool and process system and other factors on the grinding force were analyzed, thus providing further knowledge and development of ceramics grinding.

This paper presents a handover optimization scheme in LTE for a variety of velocities. This scheme adjusts the time-to-trigger parameter based on received signal strength. The proposed algorithm demonstrates a more enhanced performance during a data link failure and ping-pong effect than existing algorithms focusing on a user’s position.

In allusion to the insufficient of the traditional parameters optimization of the traditional fuzzy neural network PID controller, the parallel search characteristics of the ant colony algorithm in the whole parameter space is used. A parameters optimization method of the PID controller based combining the ant colony algorithm and fuzzy theory and neural network is proposed in this paper. The method used the ant colony algorithm to comprehensively optimize the parameters and structure of fuzzy neural network, which to be used to train and determine the parameters of the PID controller in order to get the fuzzy neural network PID controller. This method is used in the practical application of nonlinear coupled system, the experimental results show that the optimized fuzzy neural network PID controller takes the faster approximation control objectives, the shorter response time, the smaller overshoot and higher control accuracy. Consequently, the research has the theoretical significance and practical application value.

As a brand of new power transfer system, contactless energy transmission system can be used to improve the security, dependability and flexibility of the power system. Contactless energy transmission technology is suitable for some special fields, so it has already been received the great concern of foreign academia and international engineering technological circle. Energy coupling realized by contactless magnetic tank transformer as new approach of rotator excitation in synchronous machine could replace brushes and slip rings of traditional excitation. This system reduces size, weight and cost of excitation system to great extent. First, a suitable model needs to be founded because contactless energy transfer system is different from the switching power supply. We found the mutual inductance model and then gived a detailed discussion on the loosely coupled magnetic tank transformer. In accordance with the condition of the most power transmission we use the harmonic technique to realize compensation and propose series-series topology. In order to obtain the stable system the harmonic frequency of primary zero phase angle and critical load resistance could be determined based on this circuit. Second, the ideal efficiency analysis mode was proposed to simplify efficiency analysis process. In this process, the ideal efficiency determined by load resistance was introduced into the expression of input and output power and made sure of the last efficiency of contactless excitation energy transmission system. Last, when the air gap and input signal frequency have been maintained, we study the impact on the contactless energy transmission efficiency when the input signal waveform and average power changes. We selected the square wave, sine wave and triangular wave as the input signals. It will provide certain reference for the performance analysis of magnetic tank transformer.

Voltage reduction is one of the most common measures implemented to increase power reserves in emergency conditions. Since the power consumption of a composite load depends on the voltage, the power demand can be reduced by reducing the distribution voltage. Although the voltage reduction has a positive effect on power system in terms of securing reserve power, it may have a negative impact on the voltage stability in some conditions. Thus, it is necessary to analyze the effect of voltage reduction on the voltage stability. This paper analyzes the effect of voltage reduction on the voltage stability by performing PV analysis in various system conditions, such as base case on light load, heavy load, and contingency cases. In addition, we analyzed the effect of the voltage sensitivity characteristic of loads on the voltage stability.

This paper analyses the configuration characteristics of the shunt active power filter (SAPF) and introduces a novel dead time control strategy in combination with three dimensional space-vector modulation (3D-SVM) strategies. The steps for the 3D-SVM implementation are identified. The switching vectors, 3D-SVM diagram and duty cycle calculation in abc coordinates, as well as the selection of the tetrahedron are discussed in detail. Moreover, based on the analysis of the APF’S dead-time effect with 3D-SVM control, a novel predictive direct current control algorithm is used for the APF’s inverter control. Experimental results together with different control strategy are presented to validate the proposed SVM control strategy for three-phase four-wire system. The experimental results verify the correctness and validity of the proposed 3D-SVM scheme.

A method is presented to select the suitable order picking system between pick-and-sort system, a type of semi-automated put system, and carousel system, a type of parts-to-picker system, for different types of customer orders, mainly determined by density and quantity. As policies of batching and zoning are essentially order clustering, the customer order sheet can be divided into unit grids. Then the time formulation for each system can be derived according to the logical movements in a unit grid and time sequence relationship among all unit grids. Genetic algorithm is adopted to search the optimal order picking time. Subtraction value ΔT of order picking time between two kinds of system is used as the criteria to select more suitable system. In the experimental study, not only the suitability of each system with the hypothetic value of parameters can be got, but also the effect of some key factors on suitability is finally discussed.

New research opportunities are emerging as Wireless Sensor Networks (WSNs) are penetrating into the industrial domain; one such prospect is within time synchronization. For the operation of WSNs, partial or full time synchronization is needed. Time synchronization is very important in a distributed WSN for the purpose of data fusion, time interval calculation, context-free access to radio channel, coordination, event ordering and power management. This paper proposes a novel distributed time synchronization protocol for WSNs, which compensates for the nondeterministic delays by estimating the uncertainties in the synchronization packet delays. The main idea is to minimize the uncertainties in the synchronization packet delays to achieve a synchronization scheme that is accurate, efficient and has a low communication overhead. An average per hop synchronization accuracy of 2.4μs has been achieved.

A practical scheme for induction motor modelling and speed control based on field oriented control is presented in this paper. Simplified model of the induction motor is constructed for simulations, which is time-saving and very suitable for controller design in Matlab/Simulink. Actual rotor speed signal is measured to modify the original rotor flux observer, which cannot perform well at low speeds, and conventional proportional-integral controllers are used in both speed and current loops for a desired speed. Comparative simulations and experimental results demonstrate the effectiveness of the proposed scheme, and the induction motor performs well at both high and low speeds.

An information system model represents a business establishment and reflects the realities of its organization and operations. One begins to build such a model by drawing a conceptual picture of the establishment as part of its real-world domain. Object-oriented methods and languages (e.g., UML, SysML) are typically used to describe the system at this level. The resultant representation includes several textual and diagrammatic descriptions and is completely heterogeneous in form, with several different conceptual bases. This heterogeneity and multiplicity of models has caused problems that demonstrate the need for consistency between a UML use case model and its corresponding set of textual descriptions. This paper contrasts that approach with a method that provides a single, integrated graphic model that incorporates function, structure, and behavior into an underlying conceptual representation. This model is demonstrated through samples in which UML and SysML techniques were previously applied to a database analysis workflow and control of a production cell.

Most existing task scheduling algorithmsfail to aware users' QoS preference and result in low user satisfaction rate for they do not reflect users’QoS requirements. We classify QoS factors into four main QoS class which users understand well and can describe their important level, andintroduce AHP method to help user decide the class weight and avoid judgment logical error.Then, we improve existing standard PSO scheduling by use above AHP based different weights for different QoS classes to make PSO haveQoS preference awareness ability.The simulations show our method gets obviously higher user satisfaction rate and maintains the efficiency at the same time.Finally, the simulations also point out that the hierarchical scheduling is necessary to avoid the common tasks take over the special resource.

A wire-crossing is very important technique in quantum-dot cellular automata (QCA) design. Typical wire-crossing techniques have many disadvantages such as demanding of additional tasks and noise occurrence. In this paper, we use a relation between the locked and relaxed stages in order to achieve an efficient wire-crossing. The locked and relaxed stages have a fixed state such as a ground state or an excited state. We control the relation between two stages so that two crossed wires do not have any interference to each other. We design and simulate a simple wire-crossing and a XOR logic gate using the proposed wire-crossing. As a result of it, we can design and construct a regular and noiseless architecture.

The search algorithm for optimal or near optimal solutions of preventive maintenance (PM) schedules performs the search within a confined design space. This space is an enclosure which consists of two layers; the outer and the inner layer. The outer layer is defined by set of system properties while the inner by combination of set of system properties and constraints imposed on the constituent components of the system. The total number of potential PM schedules exists within the outer layer while that of feasible PM schedules is within the inner layer. As the number of constraints increases, determining this number (in outer and inner layer) becomes more complex especially within the inner layer. A pre-knowledge of this number before optimising the system for PM schedules informs the system engineer about the size of the feasible region. This size could be used in predicting the amount of work in performing a search and also in other performance measures for a given PM optimisation problem. The calculation of the size within the feasible region is the focus in this paper.

This paper is directed at the problem of designing a set of stabilizing proportional-integral-derivative (PID) controllers for each decoupled subsystem of a multi-input multi-output system based on PID stabilization theorem [1]. It is well known that state interconnection terms of ith subsystem are arising out of N-interconnected subsystem dynamics can be treated as perturbation acting on that subsystem. An LMI optimization problem is formulated to ensure the stability of the composite system while the designed decentralized controllers are employed. A genetic algorithm based search technique is adopted to select an optimal PID controller gains from a designed search space of stabilizing controllers in order to have an optimum value of performance index. A linearized model of multi-machine infinite-bus system is considered for simulation to show the effectiveness of the design procedure.

In order to overcome the problems which are difficult to be accurately predicted, such as voilent vibration, large amplitude, and pseudoperiod, we put forward a load-classification method and a model-selection method following a multi-model merit. The multi-model merit can be realized by the result of Network training, so we can forecast the load of iron and steel enterprises respectively. In this way, we can avoid the limitations of traditional load forecasting methods which simply depend on sample datas. In the framework of this model, to minimize the load forecast error is the target. On the one hand, it can be convenient to add new models into the framework, so as to improve the accuracy of the prediction, find more characteristics of the load, and better the model. On the other hand, based on the load data, we can also adaptively change the way the model is formed, so as to expand the applicability of prediction methods. By simulating different load management forecasting systems, we confirm that the effectiveness of the proposed method is verified. A software package based on the methods presented in this paper for power systems scheduling is also completed. Some native steel generation corporations have already used the system.

Two kinds of energy strategy devices of series hybrid electric bus, Ni-MH battery and super-capacitor, are used in this paper. The influence of using different energy storage devices on fuel economy of the series hybrid electric system is analyzed by power flow method. The simulation results show that the system with super-capacitor can effectively improve the efficiency of the braking energy recovery, in condition of a certain Chinese city driving cycle and the average power of the electric auxiliary power unit is 5kW.

In order to be effectively utilizing the sunlight energy into electricity, the photovoltaic modules should be perpendicularly to the sunlight direction. However, the orientation of sunlight on Earth’s surface is varied that makes it difficult to find the optimal direction. For this reason, the solar tracker should be available to drive modules in the expected direction. In this study, the solar tracker is designed based on microcontroller ATMega8535 and the position is adjusted based on the IC RTC timer response. The IC RTC is able to regulate the movement of photovoltaic modules about 15 degree per hour. The updating position of PV module is constantly changed, but the approach is enough for capturing sunlight energy for PV applications in equator region. The testing results show that the accumulative energy capturing annually from a 2250 Wp of PV system is about 500 kWh higher than that of without solar tracker.

This study simultaneously realized fast charger and low charger for electric vehicles by designing the driving power supply for the synchronization and interface of the battery system and power converter equipment of electric vehicles. In addition, it allowed the power of the output voltage and current to be supplied at a rate that is freely determined by user's setting regardless of the type of battery and power source, and also the charge and discharge devices for electric vehicles were developed using DSP. Furthermore, multi-step charging and discharging functions according to the changes in C-rate and CC (Constant Current) and CV (Constant Voltage) charging functions were realized in which the system can stably and continuously be operated with efficiency of 95% or above. Through such technological development, it has become possible to freely adjust the input voltage and output voltage according to the load condition through which production cost can be reduced and it is expected that it could be utilized in controller businesses for establishment of emergency power supply in the fields of multiple power supply apparatus of next generation electric vehicles and alternative energy that are leading the future green growth. In the future, this can be utilized in On Board Charger and Off Board Charger of EREV (Electric Range Extender Vehicle) in addition to being possible to be used in development of SMPS for power supply of high capacity power converter. It seems that it can be manufactured as product through design of DC/AC converter for next generation electric vehicles.

For system analysis and design purposes, it is meaningful discussion to define control system pole status whether a pole is significant or not. If a pole is less important, it can be canceled from the transfer function of system and system order is reduced. In this paper a method for system order reduction of transfer function using Rationalized Haar functions based on approximation and transform algorithm is presented. The Haar function set forms a complete set of orthogonal rectangular functions such as Walsh and block pulse functions. But the Haar functions have some disadvantages of calculation because of including irrational numbers such as ± sp, (p = 1, 2, ..). The Rationalized Haar functions were introduced by M. Ohkita to overcome these disadvantages. The Rationalized Haar functions constitute of rational numbers only. The applied method to solve the system order reduction of transfer function problem is superior to conventional numerical methods.

In this paper, we research on application of parameters fuzzy self-tuning PID control to radar servo system. This method overcomes some defects of traditional PID control by perfecting the PID parameter. The principles and designing method of fuzzy self-tuning PID controller are given. The excellent dynamic and static performance of airborne radar servo system based on proposed control strategy has been shown by simulation results.

This paper proposes a high power full-bridge DC-DC converter, using a center-tapped transformer and a full-wave type rectifier. The proposed converter realizes unipolar primary voltage switching, using the unipolar pulse-width modulation (PWM) technique. Also, the proposed converter reduces the freewheeling conduction loss, using the unipolar PWM technique and a resonant circuit, composed of a clamp capacitor and resonant inductor in the primary, and thus achieves high efficiency. However, because the proposed converter uses only a full-bridge circuit, center-tapped transformer, and full-wave type rectifier, the structure of the proposed converter is simple. In this paper, the operational principle of the proposed converter is described in detail, and a design example of a proposed converter prototype is shown. Finally, experimental results of the prototype are shown, to verify the feasibility of the proposed converter.

In WiMAX networks, a base station (BS) sends DL-MAP and UL-MAP messages through downlink channel to represent transmission information, such as the size of slots/symbols and modulation/coding scheme (MCS), etc., for each of downlink and uplink data bursts. However, the MAP messages act as overheads. Particularly, in a service flow (SF) with the unsolicited grant service (UGS) schedule type, it is inefficient to allocate radio resources for transmitting the MAP messages on every grant interval because the grant interval and the requested bandwidth are fixed in UGS. In this paper, we propose an adaptive scheme using policy and charging control (PCC) architecture to reduce the MAP overheads in WiMAX networks, and prove the network capacity enhancements in the view of VoIP services.

Visual sensor networks (VSN) are wireless sensor networks in which each sensor has video capture and processing capability.Power consumption may be examined for encoding, transmitting, and receiving subsystems, and research has been performed on minimizing these power levels in parallel. When multiple camera modules of a visual sensor node are aimed at the same objects with different fields of view (FOVs), the captured images may overlap. Such overlapped FOVs give rise to encoding redundancy over the VSN and also lead to increased power consumption among adjacent nodes. The power-rate-distortion (P-R-D) is determined and used to construct an optimization problem for minimizing power consumption of each node, hence maximizing node lifetime. The optimal solution provides distributed power allocation and node scheduling over the VSN at the same time, via simple information sharing, resulting in network lifetime maximization.

With the use of the power electronic device, the grid is more and more serious from the harmonic. In this paper, we improve the related link of active filter on the basis of the predecessors. And we get an ideal effect. Firstly, the traditional method uses low pass filter in the filtering process of harmonic detection technology. We introduce a digital moving average filter in this paper. Secondly, the traditional method uses the Hysteresis comparison control and triangle carrier wave control on the current control strategy. We introduce the comparison of timing control to this paper, It can easily control the sampling frequency.

Remotely controlled Home Automation is popular these days, but it is usually applicable to recent appliances only. In order to utilize old devices in the automation we have developed a model that integrates conventional electric/electronic devices into the automation. We have named the modelWhaut (Wireless Home AUTomation), in which a mobile terminal is used to trigger the control through Weband an embedded unit is used to control the target appliances. We have demonstrated usefulness of theWhaut model by implementing a mobile terminal basedsystem for controlling a conventional air-conditioner.

In this paper, a robust controller design approach is proposed for Lower Extremity Rehabilitation Robot (LERR) with automatic gait adaption. Based on the developed LERR dynamic model, the robot system is first decoupled into some independent second-order integral systems using inverbility decoupling method. Then a robust optimal PID controller is proposed for each sub-system to cope with the uncertainty in the system modeling by converting the PID controller design problem into a static output feedback H2/H∞ multi-objective optimization problem. The adaptive control methods are further investigated for a compliant gait trajectory planning. The performance of the designed controller is finally verified in the Adams-MATLAB/Simulink environment to show the effectiveness of the proposed robust control approach.

In order to compute the thermal deformation of the hydrostatic thrust bearing in the heavy type CNC equipments, a numerical research concerning temperature field of multi-pad hydrostatic thrust bearing having sector cavity, rectangular cavity, I-shaped cavity and ellipse cavity is described. Three-dimensional temperature field of gap fluid between the rotation worktable and the base has been simulated by using Finite Volume Method of CFX. This study analyzes the influence of cavity shape on the bearing temperature performance according to computational fluid dynamics and lubricating theory. It has revealed its temperature distribution. The simulation results demonstrate that an improved characteristic will be affected by cavity shape easily. Through this method, the safety of a multi-pad hydrostatic thrust bearing having different cavities can be forecasted, and the optimal design of such products can be achieved, so it can provide reasonable data for design, lubrication, experience and thermal deformation computation for hydrostatic thrust bearing in the heavy CNC equipments.

In order to solve the key technical problem in the verification process of mechanical and electrical coal mine anemometer, the paper presents digital recognition approach base on the characters of the anemometer image. First of all, collect the mirror images of the anemometer from a plain mirror which in the wind tunnels. And then we process the mirror images with secondary mirroring, grayscaling, denoising and binarization. Followed the location of the digital area can be determined and the incline distortion of the image can be adjusted. The final step is segmenting the single character in the digital character region and identify the corresponding number base on the characteristics of anemometer, which using the LED digital tube to display numbers. The experiments show that this method can accurately identify the numbers on the anemometer and has high recognition rate. The recognition time is able to meet the requirement for the verification of anemometer. Thus the method has high practical value.