Application of neural network observer for on-line estimation of salient-pole synchronous generators' dynamic parameters using the operating data

Parameter identification is critical for modern control strategies in electrical power systems which is considered both dynamic performance and energy efficiency. This paper presents a novel application of ANN observers in estimating and tracking Salient-Pole Synchronous Generator Dynamic Parameters using time-domain, on-line disturbance measurements. The data for training ANN Observers are obtained through off-line simulations of a salient-pole synchronous generator operating in a one-machine-infinite-bus environment. The Levenberg-Marquardt algorithm has been adopted and assimilated into the back-propagation learning algorithm for training feed-forward neural networks. The inputs of ANNs are organized in conformity with the results of the observability analysis of synchronous generator dynamic parameters in its dynamic behavior. A collection of ANNs with same inputs but different outputs are developed to determine a set of the dynamic parameters. The ANNs are employed to estimate the dynamic parameters by the measurements which are carried out within each kind of fault separately. The trained ANNs are tested with on-line measurements to identify the dynamic parameters. Simulation studies indicate the ANN observer has a great ability to identify the dynamic parameters of salient-pole synchronous generator. The results also show that the tests which have given better results in estimation of each dynamic parameter can be obtained

Green tea polyphenol-reduced graphene oxide: derivatisation, reduction efficiency, reduction mechanism and cytotoxicity

This paper reports on the derivatisation, reduction efficiency, reduction mechanism and cytotoxicity of green tea polyphenol-reduced graphene oxide (GTP-RGO). The reduction of graphene oxide (GO) at 90°C using a weight ratio (WR) of GTP/GO=1 resulted in the production of a stable GTP-RGO dispersion in aqueous media, as indicated by the results of ultravioletvisible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and the measurement of zeta potential and electrophoretic mobility. In addition, the results from UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis indicated the comparable reduction ability of GTP relative to the standard reducing agent, hydrazine (N2H4). The removal mechanism of epoxy group from GO via reduction reaction with GTP was investigated by implementing hybrid functional method of Becke-3-parameters-Lee-Yang-Parr (B3LYP)using Gaussian 09 software. The energy and frequency calculations showed that the GO reduction using GTP was more spontaneous and relatively took place faster than the reduction using N2H4, as evidenced by higher entropy change (ΔS) (0.039 kcal/mol·K) and lower Gibbs free energy (ΔG) barrier (58.880 kcal/mol).The cytotoxicities of GO and GTP-RGO samples were evaluated against human colonic fibroblasts cells (CCD-18Co). The GO sample was determined to be toxic even at low concentration (6.25 μg/mL), while the GTP-RGO sample possesses notably low toxicity at the same concentration. The cell culture experiments revealed that the incorporation of GTP led to a decrease in the toxicity of GTP-RGO samples

Meninjau Hukuman Mati Bagi Murtad (Kajian Hadist Tematik)

Kebebasan beragama adalah hal absolut yang diberikan oleh Allah Swt kepada manusia, karena ayat-ayat al-Qur'an yang menerangkan tentang kebebasan beragama sangat terang dan jelas adanya. Namun, pada prakteknya kita menemui fenomena yang sangat kontradiksi. Banyak ilmuwan Islam yang menyatakan bahwa kebebasan beragama tersebut berlaku bagi orang non muslim. Sedangkan bagi seorang muslim, apabila ia keluar dari agama Islam, maka baginya dua pilihan yakni taubat atau hukuman mati. Dengan melakukan kajian Hadist tematik, tulisan ini bermaksud untuk mengecek validitas pendapat para ilmuwan muslim tentang hukuman mati bagi murtad. Hasil dari penelitian ini dapat disimpulkan bahwa hadits tentang hukuman mati bagi orang murtad tidak bisa difahami secara harfiah sehingga setiap orang murtad wajib dibunuh. Namun harus difahami beserta konteksnya, yaitu bahwa orang murtad yang boleh dibunuh adalah orang murtad yang memerangi Allah dan Rasul-Nya

Challenges and Opportunities to Improve Tuberculosis Screening Among Immigrant Plantation Workers in Sabah, Malaysia

Tuberculosis (TB) among immigrants has substantial contribution to the TB epidemiology in Sabah. This study aimed to determine the yield of screening for TB disease among immigrant plantation workers in Sabah, Malaysia. This was a prospective cohort study involving 482 legal immigrant workers aged 18 years and above, consented and available at study sites during the study period. Workers with previous history of TB or currently on TB treatment were excluded from participation. Symptom based questionnaire was administered along with both chest radiograph and sputum samples collection for symptomatics participants. Out of 482 plantation workers creened, there was no case of active TB detected among the 44 (9.1%) symptomatics participants. Finding of low TB yield in this study was rather unexpected but this indicates the real challenges for the local health authority to come out with more cost effective screening programs, including reducing stigma, in active TB screening among migrant population

Penerapan Model Pembelajaran Kooperatif Rotating Trio Exchange (Rte) untuk Meningkatkan Prestasi Belajar Siswa pada Pokok Bahasan Hidrolisis Garam di Kelas XI IPA SMA N 9 Pekanbaru

The implementation of cooperative learning model Rotating Trio Exchange (RTE) has been conducted to determine the improve in student achievement and improve learning achievement category on the subject of salt hydrolysis in class XI SMA N 9 Pekanbaru. Forms of this research is experimental research design with pretest - posttest. Time data collection between February 8 to April 13, 2016. The sample consisted of two classes, grade XI IPA 3 as the control class and class XI IPA 5 as an experimental class selected at random. Grades given experimental treatment with the application of Rotating Trio Exchange (RTE), while the control class are given learning lecture method. Data analysis technique used is the t-test. Based on the analysis of data processing obtained t¬hitung> ttable is 4.94> 1.67 means that the implementation of cooperative learning model Rotating Trio Exchange (RTE) can improve student achievement on the subject of salt hydrolysis in class XI SMA N 9 Pekanbaru. Category increase student achievement in the classroom experiment with a normalized gain value (N-gain) of 0.91 is included in the high category

An Efficient Parallel Quarter-sweep Point Iterative Algorithm for Solving Poisson Equation on SMP Parallel Computer

A new point iterative algorithm which uses the quarter-sweep approach was shown to be much faster than the full-and half- sweep point iterative algorithms for solving two dimensional Poison equation (Othman el at. 1998». However, the last two algorithms were found to be suitable for parallel implementation (Evans 1984) and Ali el at. (1997». In this paper, the parallel implementation of the new algorithm with the chessboard (CB) strategy on Symmetry Multi Processors (SMP) parallel computer was presented. The experimental results of a test problem were compared with the later two parallel algorithms

Linear-nonlinear stiffness responses of carbon fiber-reinforced polymer composite materials and structures: a numerical study

The stiffness response or load-deformation/displacement behavior is the most important mechanical behavior that frequently being utilized for validation of the mathematical-physical models representing the mechanical behavior of solid objects in numerical method, compared to actual experimental data. This numerical study aims to investigate the linear-nonlinear stiffness behavior of carbon fiber-reinforced polymer (CFRP) composites at material and structural levels, and its dependency to the sets of individual/group elastic and damage model parameters. In this regard, a validated constitutive damage model, elastic-damage properties as reference data, and simulation process, that account for elastic, yielding, and damage evolution, are considered in the finite element model development process. The linear-nonlinear stiffness responses of four cases are examined, including a unidirectional CFRP composite laminate (material level) under tensile load, and also three multidirectional composite structures under flexural loads. The result indicated a direct dependency of the stiffness response at the material level to the elastic properties. However, the stiffness behavior of the composite structures depends both on the structural configuration, geometry, lay-ups as well as the mechanical properties of the CFRP composite. The value of maximum reaction force and displacement of the composite structures, as well as the nonlinear response of the structures are highly dependent not only to the mechanical properties, but also to the geometry and the configuration of the structures