Earticle

In this study, we propose a computerized maintenance management system based on integration of reliability centered maintenance (RCM) and automated data gathering using multi-agent technology. The objective of the proposed system is to support decision-making of maintenance managers by providing up-to-date reliability assessment of facilities in automated manner. To do so, this system was integrated by the following S/W components; 1) a computerized maintenance management system (CMMS) to record failure and maintenance history of facilities, 2) a multi-agent system (MAS) to automate data gathering to monitor condition of facilities in real time. A web based application was also developed, which analyzes failure patterns in order to provides reliability risk assessment such as expected remaining life of facilities, expected failure rates, and risk of parts to fail. A case study of implementing the proposed system in an automotive part production company was represented.

In this paper, a hybrid PSO_Fuzzy_PID controller is designed for speed control of a gas turbine. The aim of the controller is to maintain the turbine speed and the exhaust temperature in a desired interval during startup and operating condition. Here, different parts of the fuzzy controller such as fuzzification, rule base, inference engine, defuzzification, and particle swarm optimization (PSO) algorithm are presented. computer simulations of the controller and gas turbine based on Matlab / simulink simulation platform are performed to investigate the effectiveness of the proposed algorithm. The performance of the proposed algorithm is evaluated during startup and operating condition of the gas turbine. Simulation results well show that the response of the PSO_Fuzzy_PID controller is effectively improved compared with other controllers. The characteristics of the step response such as rise time, settling time and overshoot are considerably decreased, and the value of the steady state error is minimized.

As integration densities continue to increase, interconnection has become one of the most important factors in determining the performance of multi-core processors. Recently, in order to reduce the delay due to interconnection, many studies have focused on the 3D multi-core processors. Compared to 2D multi-core architecture, 3D multi-core architecture gets decreased interconnection delay and lower power consumption owing to reduced wire length. Despite the benefits mentioned above, 3D design cannot be practical because it causes serious thermal problems in multi-core processors due to high power density. In this paper, we analyze temperature behavior of 3D multi-core processors according to various placement of core and level-2 cache. According to our simulation results, the floorplan where the core is stacked adjacently to the level-2 cache can reduce the temperature by 22% with 4-layers, and by 13% with 2-layers on the average, compared to the floorplan where the core is stacked adjacently to the core.

A novel approach based θ-Particle Swarm Optimization (θ-PSO) is proposed for optimal selection of the output feedback damping controller parameters for unified power flow controller (UPFC) in order to improve the damping of power system oscillations. The selection of the output feedback gains for the damping controllers is converted to an optimization problem with the time domain-based objective function which is solved by the θ-PSO algorithm. For designing, only local and available state variables are selected as the input stabilizing signals of each controller. Thus, structure of the proposed output feedback controller is simple and easy to implement. To ensure the robustness of the designed controllers, the design process takes into account a wide range of operating conditions and system configurations. Simulation results demonstrate that UPFC with the proposed output feedback controller can more effectively improve the dynamic stability, damp the oscillations, and enhance the transient stability of power system compared to the classical PSO and phase compensation based damping controllers. Moreover, the system performance analysis under different operating conditions shows that the δE based controller is superior to the mB based controller.

The work develops a redundant software system for subsea blowout preventers, including control logics, human-machine interface (HMI) programs, remote access and redundant databases in order to meet the high reliability requirement of subsea drilling. The Bayesian networks (BN) for control logics, HMI programs and redundant databases are built and then the whole BN are established. The quantitative reliability evaluation is performed by using Netica software. The probability of software failure is evaluated via forward analysis, and the posterior probability given the failure is evaluated via backward analysis. The mutual information is researched in order to assess the important degree of basic events. The results show that the probability of software failure is 0.04%, which can meet the requirement of subsea drilling. The triple common cause failure should be paid more attention in order to improve the software performance. In addition, the control logics have the most important influences on software safety; the HMI programs have the least important influences; and the redundant databases are in between.

A new type controller, recurrent fuzzy neural networks-fuzzy-sliding mode controller (FRNN-FSMC), is developed for a class of large-scale systems with unknown bounds of high-order interconnections and disturbances. The main purpose is to eliminate the chattering phenomenon and to overcome the problem of the equivalent control computation. The FRNN-FSMC, which incorporates the recurrent fuzzy neural network (RFNN), fuzzy logic controller (FLC) and the SMC, can eliminate chattering using a fixed boundary layer around the switch surface. Within the boundary layer, where the FLC is applied, the chattering phenomenon, which is inherent in a SMC, is avoided by smoothing the switch signal. Moreover, to compute the equivalent controller, a feed-forward RFNN is used. The stability of the whole system is analyzed via the Lyapunov methodology. In this study, we propose an effective method to select some key controller parameters in an optimal manner by using the genetic algorithm (GA), so that a high performance of the overall system's response can be achieved. The effectiveness and efficiency of the proposed controller and optimization method were tested using highly interconnected nonlinear systems as examples.

This paper presents the system modeling and control design for the load voltage regulation using distribution static compensators (D-STATCOMs). The decoupling control based on the dq reference frame with the symmetrical optimum method is applied to design the D-STATCOM current and DC voltage controllers. The modeling strategy similar to that used for the field-oriented control of three-phase AC machines is employed to model the distribution system integrating with the D-STATCOM and its control circuit. This derived model is used for the load voltage controller design based on the linearized technique, called classical loop shaping method. A simplified 11-kV, 2-bus test power system is employed for simulation. Satisfactory results obtained by simulating the proposed model are compared with those obtained by the switching control of D-STATCOM power circuit created in MATLAB’s Power System Blockset. As a result, the effectiveness of proposed model is verified. This design gave satisfactory responses to guarantee at least 3 dB of the gain margin and 40 of the phase margin.

The Next Future Commercialized 4WD Electric Vehicle Future (EV) is designed to minimize the autonomous, the time range of starting and acceleration, in order to improve the vehicle stability and the other dynamic performances for this reason the multi-input multi-output fuzzy logic controller (MIMO-FLC) was presented and implemented in the electrical traction system forming the maximum control process, the advantages of this control structure ( MIMO-FLC) is to give more and more safety and stability for the 4WD comparing with the classical fuzzy controller , The main object of this paper is to show the efficiency of the MIMO-FLC applied on four speeds electric vehicles, the 4WD is powered by four induction motors of 15 kilowatts of each one developing an effort of 338 N. m as global torque so this kind of vehicle consist of two front directing wheels and rear propulsion wheels . The MIMO-FLC control technique is simulated in MATLAB SIMULINK environment. The simulation results proves that the MIMO-FLC method decreases the error speeds of the differential electronic at any curves and mainting the vehicle stability at the curved roads when the transient oscillations are decreased and give good dynamical performance for the vehicle using four induction motors for motion ,it’s clearly that the proposed control present more robustness comparing with the SISO classical ones which have many more problems during the vehicle driving , the results obtained present satisfactory and the vehicle designer must take into consideration the stability effect for the 4WD vehicle moving in road with different topologies using the MIMO-FLC control.

In this paper, we propose a design method of the tracking and controlling AUV(autonomous underwater vehicle) that has wide range of velocity. The state feedback controllers are designed according to determined surge speed and then a fuzzy controller is designed in a way that the outputs of the state feedback controller are combined by the surge speed of AUV, so that when the surge speed changes, the AUV control becomes stable. By simulation using Matlab/Simulink, the performance of the proposed controller is shown to be efficient.

In industries, overhead cranes are commonly employed to lift and lower materials or to move them horizontally. A combining sliding mode control method is proposed for overhead crane systems in this paper. The ideas behind the combining sliding mode are as follows. First, an intermediate variable is introduced by dividing the system states into two groups. Then, a sliding surface is defined on basis of the intermediate variable. The control law is deduced from Lyapunonv direct method to asymptotically stabilize the sliding surface. The stability of the system states is also proven. Simulation results demonstrate the feasibility of the presented method through transport control of an overhead crane system.

A u-Healthcare system should support mobility and accessibility besides sorts of medical information. The 5-HD (Healthcare Data) includes digitalized ECG, Blood pressure, Body composition, Body Temperature and Weight. In this work, we design and implement a new 5-HD measurement system that includes data collection modules and a smartphone application based on the Bluetooth communication. Each data collection module can generate digitalized biomedical signal continuously and send it to the user’s smartphone application. The application can process and show up the signal and healthcare data as a kind of all-in-one type through the united user interface and also can forward to the designated healthcare server system. We also had adjusted the Bluetooth application data format to maximize the data transfer rate among the modules and smartphone application. The 5-HD measurement system can give us more easiness, accessibility and mobility for the u-Healthcare environment than any special-purposes handy or mobile measurement system.

The memory deduplication mechanism has been used in virtualized environment. The Linux kernel, however, was implemented as anonymous pages with the same content across inter-virtual machines. To resolve this problem, previous work was considered in the page cache inside the guest. So, we propose a KVM-based deduplication mechanism which is used on the host page cache. It does not require a modification of the guest kernel. Our implementation detects more sharing opportunities than the KSM (by factor of 2x), and its CPU overhead is less than 4%. Also, it reduces the page swap in/out by 40% compared to default VMs in the worst case. Thus, the page cache deduplication is required in virtual environments.

Proxy Mobile IPv6 (PMIPv6), a network-based localized mobility protocol, allows a mobile node (MN) to move around within the same PMIPv6 domain by keeping the same IP address. However, PMIPv6 does not support the global handover since it supports only an intra-domain handover. To support the global handover, MNs need to load the protocol stack for the global mobility. Our proposed scheme enables the MN’s session to be connected without any support of PMIPv6 protocol during the global handover. In addition, it reduces the packet transmission delay by performing the Route Optimization (RO) after the MN’s global handover. In this paper, we compare our proposed scheme with the existing Roaming scheme. As a result, the proposed scheme reduces the packet transmission delay by 25% and the packet loss by 78% compared with the existing one. In other words, our scheme supports the seamless and reliable handover for MN.

A power allocation scheme for the secondary user when the primary user employs the full duplex relay (FDR) is proposed in cognitive radio system. When the FDR is deployed in primary system, the primary relay and receiver suffers the interference from the secondary transmitter in order to share the spectrum of the primary user. Therefore, the power allocation scheme to satisfy the interference constraint is needed for the spectrum sharing. Thus, we propose a new power allocation scheme to satisfy the quality of service (QoS) of he primary user. Since the proposed power allocation scheme does not need the nstantaneous channel state information (CSI), the proposed scheme not only has feedback burden, but also can be robust the outdated CSI environment.

In this paper, we propose a resource allocation and Tx power control scheme, called resource allocation and power control (RAPC) in an LTE-Advanced device-to-device (D2D) network. In the proposed scheme, the macro base station (mBS) and D2D senders (D2DSs) service macro user equipment (mUEs) and D2D receivers (D2DRs) use the different frequency bands and Tx power chosen as D2D links’ locations in inner and outer zones to reduce interference substantially. We analyze and compare the proposed scheme and random resource allocation (RRA) scheme with fractional frequency reuse (FFR) systems in terms of the system throughput for DL and outage probability according to the number of D2D user’s (D2DR) traffic density. Simulation results show that the RAPC scheme has better performance than the random resource allocation (RRA) scheme performance in terms of the system throughput and outage probability for mUEs and D2DRs.

We present an automated control system, to support astronomical observations for amateur astronomers. Our system provides the trajectory calculation of a specific astronomical object, and controls the astronomical telescope to immediately observe that astronomical object, based on the various information such as the current time, the current location, and the astronomical databases. Comparing with the previous commercial systems, our system provides more automated supports to the user, in a more cost-effective way.

As the access speed gap between DRAM and storage devices such as hard disk drives is ever widening, the I/O module dominantly becomes the system bottleneck. Meanwhile, the map-reduce parallel programming model has been actively studied for the last few years. In this paper, we will show empirically show that flash memory based SSD(Solid State Drive) is very beneficial when used as local storage devices in IO-intensive map-reduce applications (e.g. sorting) using Hadoop open source platform. Specifically, we present that external sorting algorithm in Hadoop with SSD can outperform the algorithm run with hard disk by more than 3. In addition, we also demonstrate that the power consumption can be drastically reduced when SSDs are used.

The existing e-Mail could not act as legal evidence due to the lack of the non-repudiation functionality that the related matter has or has not been transferred between the related parties. From such perspective, the publicly authorized electronic address-based #-Mail has the greatest characteristic that distinguishes it from the existing e-Mail by issuing distribution certificate for non-repudiation through publicly authorized document repository. Also, in Korea, #-Mail has been recognized as one of the legal trade proof documents such that publicly authorized electronic address-based #-Mail solution is in development. In this study, under such motive, the publicly authorized electronic address-based #-Mail solution that can function as a distribution client was developed and the study that distinguishes itself from the application of activating such #-Mail was conducted. New functions were suggested as implementation cases, this study can be said to have a distinguished significance from the existing studies.

This paper presents an efficient clustering scheme for data aggregation considering mobility to reduce the network lifetime in Mobile Wireless Sensor Networks (MWSNs). In MWSNs, an accurate data aggregation is affected by failure in time-critical data transmission due to the differences of mobility between cluster head and its members. Consequently, selecting a node with dissimilar mobility from members as a cluster head can lead to unstable clustering. Hence, we propose a clustering scheme considering the mobility and energy to minimize the number of nodes that moves away from the current cluster head before the next cluster formation. The proposed scheme is processed in two-stages. During the first phase of clustering, all nodes calculate their potential score based on the similarity of movement, residual energy and density in distributed manner. Each node decides whether the node itself should be a cluster head or not using a potential score. The second stages, each node select its cluster head among those cluster head candidates considering the link connection time and an amount of energy to transmit the collected data. A higher residual energy node with the smallest movement deviation is selected as a cluster head. In addition to, we propose a mobility adaptive slot utilization to reduce the idle slot. The experimental result shows that the proposed scheme can provide an efficient data aggregation in terms of network lifetime and the number of nodes leaving its cluster head.

For a real-time system, the system correctness depends not only on the correctness of the logical result of the computation but also on the result delivery time. Real-time Operating System (RTOS) is widely accepted in designing real-time systems. The real-time performance is achieved by using real-time mechanisms through data communication and synchronization of inter-task communication (ITC) between tasks. Therefore, benchmarking the response time of real-time mechanisms is a good measure to predict the performance of real-time systems. This paper aims to analyze the response characteristics of real-time mechanisms in kernel and user space for real-time embedded Linux: RTAI and Xenomai. The performance evaluations of real-time mechanisms depending on the changes of task periods and load are also conducted in kernel and user space. Test metrics are jitter of periodic tasks and response time of real-time mechanisms including semaphore, real-time FIFO, Mailbox and Message queue. The results are promising to estimate deterministic real-time task execution in implementing real-time systems using RTAI or Xenomai.

The demands for GPS have explosively increased in various areas such as geodetic survey, car navigation, geophysics and weather. But countless time and efforts are required to process GPS data so that automation of data processing is in definite need to solve this issue. Therefore this research had developed a console application which automatizes GPS data processing based on C# and Bernese 5.0. By generating favorable performance of GPS data processing test with deviations of 0.0140m in maximum in notification achievement latitude, longitude, and ellipsoidal height direction, this research suggested possibility of data processing automation though developed application.