Universiti Teknikal Malaysia Melaka: UTeM Open Journal System
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Grid Federation: Number of Jobs and File Size Effects on Jobs Time
Get PDFGrid federation is fast emerging as an alternative solution to the problems posed by the large data handling and computational needs of the existing numerous worldwide scientific projects. Efficient access to such extensively distributed data sets has become a fundamental challenge in grid computing. Creating and placing replicas to suitable sites, using data replication mechanisms can increase the system’s performance. Data Replication reduces data access time, ensures load balancing as well as narrows bandwidth consumption. In this paper, an enhanced data replication mechanism called EDR is proposed. EDR applies the principle of exponential growth/decay to both file size and file access history, based on the Latest Access Largest Weight (LALW) mechanism. The mechanism selects a popular file and determines an appropriate number of replicas as well as suitable grid sites for replication. It establishes the popularity of each file by associating a different weight to each historical data access record. Typically, recent data access record has a larger weight, which signifies that the record is more relevant to the current situation of data access. By varying the number of jobs as well as file sizes, the proposed EDR mechanism was simulated using file size and job completion time as the variable metrics. Optorsim simulator was used to evaluate the proposed mechanism alongside the existing Least Recently Used (LRU), and Least Frequently Used (LFU) Mechanisms. The simulation results showed that job completion time increases by the growth in both file size and number of jobs. EDR shows improved performance on the mean job completion time, compared to LRU and LFU mechanisms
Hybrid Fuzzy-PID Bidirectional Speed Controller for BLDC with Seamless Speed Reversal using Direct Commutation Switching Scheme
Get PDFBrushless Direct Current (BLDC) motors have attracted a lot of attention due to their performance capabilities. The Proportional Integral (PID) controller remained popular due to its simplicity. However, PID’s performance deteriorates during nonlinear loads conditions. Controllers have been developed to overcome the limitations of the PID controllers but focused on forwarding motor only. Furthermore, lack of literature regarding the bidirectional speed control of BLDC motor has been reported. In this paper, a Hybrid Fuzzy-PID speed controller for BLDC with seamless speed reversal using direct commutation switching scheme was proposed. The controller uses Fuzzy rule base and the switching scheme for bidirectional operations. MATLAB/Simulink was used to develop and test the controller. The controller was tested for several test cases and compared to a ZN-Tuned PID controller. The controller performed efficiently for all the test cases and has better results compared to the PID controller under same test cases
READINESS FACTORS FOR AMT IMPLEMENTATION:A CONCEPTUAL STUDY
Get PDFNowadays the advanced manufacturing technology (AMT) becoming significant for large and small manufacturing companies operation.Especially for small and medium enterprise (SMEs) by implementing AMTit is a value added that will ensure them to sustain and competitive among rivals. However, most of the AMT implementers are failure to adapt with AMT due to lack of knowledge, skill and capital. The aim of this research is to recognize the readiness factors for SMEs in adopting the AMT in southern Malaysia. This research proposed a conceptual model for SMEs to highlight readiness factors before AMT implementation happen
Thermophysical Properties Of Nanocarbon Particles In Ethylene Glycol And Deionized Water
Get PDFThe recent research has demonstrated that nanofluids have provided significantly better thermophysical properties than the base fluids because of its novel properties. The nanofluids proved to have higher heat transfer property and specific heat capacity at a very low particle concentration than conventional heat transfer fluid. Generally, the available base fluid such as ethylene glycol (EG) and deionized water (DI) has a limitation in terms of thermophysical properties like thermal conductivity and heat transfer. An innovative way to overcome this limitation is by adding nanoparticles to the base fluid to form nanofluid. In this paper, the proposed objective is to formulate a stable nanofluid from HHT24 carbon nanofiber (CNF) and –OH functionalized multiwalled carbon nanotubes (MWCNT-OH) in a base fluid with the presence of polyvinylpyrrolidone (PVP) as the stabilizer through two-step preparation process. Then, the thermal conductivity and heat transfer were investigated at three different temperatures (6°C, 25°C and 40°C). Nanofluids tested for thermal conductivity and heat transfer shows that most of the samples achieved an enhancement in EG and DI based nanofluids when CNF HHT24 and MWCNT-OH particle was added. Overall, this studies shows that nanocarbon material is a great alternative to being used in conjunction with ethylene glycol and deionized water as a heat transfer media in a cooling application.
Electromyography Signal Analysis Using Time and Frequency Domain for Health Screening System Task
Get PDFMusculoskeletal disorder (MSDs) isone of the most popular issues of occupationalinjuries and disabilities. It has a big impact andcreates a big problem for industries to be resolved.In MSDs, electromyography (EMG) is one of themethods to be studied in order to detect MSDsproblem. This research focuses on the EMG signalanalysis by using time domain and frequencydomain (Welch Power Spectral Density) method.It gives more information from the signal and itis the most suitable method for classifying themoments in order to identify the behaviouralof the signals. Axial rotational reach and upperlevel reach task from Health Screening Program(HST) is performed using functional range ofmotion (FROM) by considering left and rightbiceps brachii muscles to be analysed. There aretwo parameters chosen for each time and for eachfrequency domain to be tested, which are meanan absolute value (MAV) and root mean square(RMS) for time domain. Median frequency (MDF)and mean frequency (MNF) are for frequencydomain. The results showed that frequencydomain analysis is able to give more parameterand information of the signal. Upper level reachacquires more effort to perform the task comparedto axial rotational reach for left and right bicepsbrachii. However, different performances ofthe signal obtained in classifying the momentsfrom t-test analysis due to p-value. The bestperformance to classify signal characteristics is thelowest p-value which is 7.369E-05 (MAV), 6.9504E-05 (RMS), 0.0054 (MDF). However, p-value for0.0515 is rejected because it is greater than 0.05.It is concluded that the frequency domain is ableto give more information of the signal, howeverfor classifications moments, time domain is bettercompared to the higher accuracy result. This studyis very important to give the idea in the futureanalysis of EMG signal in the aspect of detectingMSDs in human body in health screening task
Interference Reduction Using MMSE-DFE Equalizer with One-Third ICI-SC STFBC for MIMO-OFDMA System
Get PDFOrthogonal frequency division multiple access (OFDMA) allows simultaneous low data rate transmission for several users. However, as one symbol interferes with subsequent symbol, it will produce a phenomenon called intersymbol interference (ISI) which has similar effect as noise and thus making the communication less reliable. Besides that, Doppler spread due to channel time-variation destroys the orthogonality in OFDMA system and degrade the system performance with intercarrier interference (ICI). In order to solve this issue, minimum mean square error-decision feedback equalizer (MMSE-DFE) with one-third (ICI-SC) subcarrier mapping method using space-time-frequency block codes (STFBC) is proposed. The objective is to minimize both ISI and ICI effects by evaluating pairwise error probability (PEP) and bit error rate (BER) performances. From the simulation results, MMSE-DFE with one-third ICI-SC technique shows the best result for MIMO-OFDMA system with 25% improvement of PEP and 4.8% improvement of BER
Electrolysis Synthesis and Characterization Properties of Nickel Oxide Nanoparticle
Get PDFSynthesis nickel oxide nanoparticles based on electrolysis method at high voltage (55 V), with concentration natrium citrate optional condition at 0.3 M. The nickel oxide nanoparticles sample were characterized using, X-Ray Diffraction (XRD), Fourier Transform Infrared spectrometer (FTIR), Thermo Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). XRD result show diffractogram from the product have the same lattice with standard ICDD, Thermogram shows at a temperature above 400 ºC already formed nickel oxide nanoparticles. Spherical nanoparticles were obtained by this method
Real-time Key Management for Wireless Mesh Network
Get PDFWith the rapid technological development of wireless, wireless mesh network (WMN) is one of the network models which is gradually showing its superiority through several applications and projects thus it is becoming the key of technology for IoT. Due to the vulnerable environment, limited resource and open communication channel, the security design for such networks are significantly challenging. By using realtime synchronization method between transceiver devices in the WMNs, we propose an algorithm based on secret sharing method in which each node generate its key depend on its physical information and the real-time clock. Therefore, we can manage efficiently public and private keys for data encryption and prevent several external attacks to WMNs. We also propose a specific protocol to secure our keys while transferring between devices to prevent internal attacks
Utilization of Max-Min User Relay in Cooperative NOMA Systems
Get PDFNon-orthogonal multiple access (NOMA) has been focused to increase system capacity and spectral efficiency for the fifth generation (5G) mobile networks. In order to improve the performance of the NOMA systems with successive interference cancellation (SIC), a max-min user relay assisted cooperative NOMA scheme is investigated in this paper. The derived closed-form expression for outage probability is verified through Monte Carlo simulation results. We found that the performance with max-min relay outperforms the random relay. It is also shown that the performance of the destination user (DU) improves with the power allocation coefficient of DU. However, we noticed that there is an optimal value to minimize the outage probability of the relay-user (RU)
Wearable Posture Identification System for Good Sitting Position
Get PDFEvery human spends most of their time remain seated especially students. A good posture during seated is important to determine the human health, while a bad posture during seated posture can lead to numerous diseases. This paper explained the design and development of wearable posture identification system using accelerometers to determine the good human posture in a seated position. Two accelerometers were used to determine the posture of an individual. The first accelerometer was placed on the human lumbar spine while the second accelerometer was placed on the human cervical spine. The calculation of the angle in determining the posture was processed using Arduino. There is three experiment was conducted: calibration test, performance measurement test and real-time analysis test. The calibration test was conducted to determine the percentage error of the accelerometer when compared with goniometer at static condition. The second experiment was conducted to determine the percentage error of between accelerometer and electrogoniometer at the dynamic condition. The third experiment was conducted to test the accelerometer in real life environment. The result showed that accelerometer has the percentage error less than 3% when compared to goniometer and electrogoniometer. This system can monitor and identify the good and bad sitting posture