13,718 research outputs found
Multiple bottlenecks sorting criterion at initial sequence in solving permutation flow shop scheduling problem
This paper proposes a heuristic that introduces the
application of bottleneck-based concept at the beginning of an initial sequence
determination with the objective of makespan minimization. Earlier studies
found that the scheduling activity become complicated when dealing with
machine, m greater than 2, known as non-deterministic polynomial-time
hardness (NP-hard). To date, the Nawaz-Enscore-Ham (NEH) algorithm is
still recognized as the best heuristic in solving makespan problem in
scheduling environment. Thus, this study treated the NEH heuristic as the
highest ranking and most suitable heuristic for evaluation purpose since it is
the best performing heuristic in makespan minimization. This study used the
bottleneck-based approach to identify the critical processing machine which
led to high completion time. In this study, an experiment involving machines
(m =4) and n-job (n = 6, 10, 15, 20) was simulated in Microsoft Excel Simple
Programming to solve the permutation flowshop scheduling problem. The
overall computational results demonstrated that the bottleneck machine M4
performed the best in minimizing the makespan for all data set of problems
Program latihan industri di Kolej Universiti Teknologi Tun Hussein Onn : kajian terhadap perlaksanaan sistem penilaian
Kajian yang dijalankan adalah bertajuk "Program Lalilian lndustri Di Kolej Universiti Teknologi Tun Hussein Onn : Kajian Terhadap Perlaksanaan Sistem Penilaian". Sampel terdin daripada 6 orang pakar serta 63 orang pelajar yang terlibat dalam latihan industri. Maklumat yang diperolehi berdasarkan kaedah kualitatif dan kuantitatif Data dianalisis untuk meninjau kaedah penilaian yang dijalankan dan seterusnya memastikan apakali sistem penilaian yang perlu diperbaiki. Secara keseluruhannya, kebanyakan responden berpendapat bahawa sistem penilaian yang sedia ada adalah perlu diperbaki dan disistematikkan selaras dengan ISO 9000 : 2001. Berdasarkan daripada keputusan yang diperolehi dan bimbingnan pakar dari Unit Latihan lndustri KUiTTHO, maka satu "Buku Panduan Penilaian Latihan lndustri" dihasilkan dengan panduan yang ringkas dan lampiran borang-borang yang telah diperbaiki dan diubahsuai. Diharapkan produk mi dapat digunakan untuk masa-masa akan datang
Phasor Estimation for Grid Power Monitoring: Least Square vs. Linear Kalman Filter
International audienc
Current Status and Future Trends of Power Quality Analysis
In this article, a systematic literature review of 153 articles on power quality analysis in
PV systems published in the last 20 years is presented. This provides readers with an overview
on PQ trends in several fields related to instrumental techniques that are being used in the smart
grid to visualize the quality of the energy, establishing a solid literature base from which to start
future research. A preliminary appreciation allows us to intuit that higher-order statistics are not
implemented in measurement equipment and that traditional instrumentation is still used for the
performance of measurement campaigns, not yielding the expected results since the information
processed does not come from an electrical network from 20 years ago. Instead, current networks
contain numerous coupled load effects; thus, new disturbances are not simple; they are usually
complex events, the sum of several types of disturbances. Likewise, depending on the type of
installation, the objective of the PQ analysis changes, either by detecting certain events or simply
focusing on seeing the state of the network
Automatic classification of power quality disturbances using optimal feature selection based algorithm
The development of renewable energy sources and power electronic converters in conventional power systems leads to Power Quality (PQ) disturbances. This research aims at automatic detection and classification of single and multiple PQ disturbances using a novel optimal feature selection based on Discrete Wavelet Transform (DWT) and Artificial Neural Network (ANN). DWT is used for the extraction of useful features, which are used to distinguish among different PQ disturbances by an ANN classifier. The performance of the classifier solely depends on the feature vector used for the training. Therefore, this research is required for the constructive feature selection based classification system. In this study, an Artificial Bee Colony based Probabilistic Neural Network (ABCPNN) algorithm has been proposed for optimal feature selection. The most common types of single PQ disturbances include sag, swell, interruption, harmonics, oscillatory and impulsive transients, flicker, notch and spikes. Moreover, multiple disturbances consisting of combination of two disturbances are also considered. The DWT with multi-resolution analysis has been applied to decompose the PQ disturbance waveforms into detail and approximation coefficients at level eight using Daubechies wavelet family. Various types of statistical parameters of all the detail and approximation coefficients have been analysed for feature extraction, out of which the optimal features have been selected using ABC algorithm. The performance of the proposed algorithm has been analysed with different architectures of ANN such as multilayer perceptron and radial basis function neural network. The PNN has been found to be the most suitable classifier. The proposed algorithm is tested for both PQ disturbances obtained from the parametric equations and typical power distribution system models using MATLAB/Simulink and PSCAD/EMTDC. The PQ disturbances with uniformly distributed noise ranging from 20 to 50 dB have also been analysed. The experimental results show that the proposed ABC-PNN based approach is capable of efficiently eliminating unnecessary features to improve the accuracy and performance of the classifier
Power Quality Investigation with Wavelet Techniques
Electric power quality is an aspect of power engineering that has been with us since the inception of power systems. However, the topics in power quality have only attracted interests over the past few years because of the increasing usage of electronically controlled equipments. The power quality problem causes interruptions to the sensitive electrical or electronic equipment and results in very expensive consequences. Wavelet techniques will be studied in this paper for analysing monitored power quality data. A case study based on the measurement of a University of Queensland site was studied using the proposed wavelet approach
Investigating the Effect of Water Contamination on Gearbox Lubrication based on Motor Control Data from a Sensorless Drive
Water is one of the most significant destructive contaminations to lubricants which in turn lead to more power consumption and early damage to rotating machines. This study explores the effect of water contents in gearbox lube oil on the responses of electrical supply parameters. A two stage gearbox based mechanical transmission system driven by a sensorless variable speed drive (VSD) is utilised to investigate experimentally any measurable changes in these signals that can be correlated with water contamination levels. Results show that the supply parameters obtained from both external measurements and the VSD control data can be correlated to the contamination levels of oil with water and hence can be based on for an instant diagnosis of water contamination. Particularly, the voltage and hence the power responses are more sensitive to the water contents than that of current because the VSD regulates more the voltage to adapt the small load changes due to the water induced lubrication degradation. Simultaneously, vibration also shows changes which agree with that of power supply parameters
Review of Detection and Classifcation Techniques for Power Quality Events
This paper presents a short review on the field of power quality. Power quality is directly related to the performance of the electric equipment. The accurate and reliable operation and life of equipment based on the quality of input power. So the main concern on the power quality is for satisfactory operation of each connected equipment. Detection, classification and mitigation are the main steps used in the power quality analysis. Accurate detection and classification gives effective mitigation solutions. A number of research papers are reviewed and presented here which gives some knowledge about power quality field
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