Search results for: the central pattern generator (CPG)

Authors: Qian Chen, Lin Xu, Ping Ju, Zhuoran Li, Yiping Yu, Yuqing Jin

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The operation of power grid is becoming more and more complex and difficult due to its rapid development towards high voltage, long distance, and large capacity. For instance, many large-scale wind farms have connected to power grid, where their fluctuation and randomness is very likely to affect the stability and safety of the grid. Fortunately, many new-type equipments based on power electronics have been applied to power grid, such as UPFC (Unified Power Flow Controller), TCSC (Thyristor Controlled Series Compensation), STATCOM (Static Synchronous Compensator) and so on, which can help to deal with the problem above. Compared with traditional equipment such as generator, new-type controllable devices, represented by the FACTS (Flexible AC Transmission System), have more accurate control ability and respond faster. But they are too expensive to use widely. Therefore, on the basis of the comparison and analysis of the controlling characteristics between traditional control equipment and new-type controllable equipment in both time and space scale, a coordinated optimizing control method within mutil-time-space frame is proposed in this paper to bring both kinds of advantages into play, which can better both control ability and economical efficiency. Firstly, the coordination of different space sizes of grid is studied focused on the fluctuation caused by large-scale wind farms connected to power grid. With generator, FSC (Fixed Series Compensation) and TCSC, the coordination method on two-layer regional power grid vs. its sub grid is studied in detail. The coordination control model is built, the corresponding scheme is promoted, and the conclusion is verified by simulation. By analysis, interface power flow can be controlled by generator and the specific line power flow between two-layer regions can be adjusted by FSC and TCSC. The smaller the interface power flow adjusted by generator, the bigger the control margin of TCSC, instead, the total consumption of generator is much higher. Secondly, the coordination of different time sizes is studied to further the amount of the total consumption of generator and the control margin of TCSC, where the minimum control cost can be acquired. The coordination method on two-layer ultra short-term correction vs. AGC (Automatic Generation Control) is studied with generator, FSC and TCSC. The optimal control model is founded, genetic algorithm is selected to solve the problem, and the conclusion is verified by simulation. Finally, the aforementioned method within multi-time-space scale is analyzed with practical cases, and simulated on PSASP (Power System Analysis Software Package) platform. The correctness and effectiveness are verified by the simulation result. Moreover, this coordinated optimizing control method can contribute to the decrease of control cost and will provide reference to the following studies in this field.

Keywords: FACTS, multi-space-time frame, optimal control, TCSC

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Authors: N. Soli, B. Chaouachi, M. Bourouis

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We propose in this work the thermodynamic feasibility study of the operation of a refrigerating machine with absorption-diffusion with mixtures of hydrocarbons. It is for a refrigerating machine of low power (300 W) functioning on a level of temperature of the generator lower than 150 °C (fossil energy or solar energy) and operative with non-harmful fluids for the environment. According to this study, we determined to start from the digraphs of Oldham of the different binary of hydrocarbons, the minimal and maximum temperature of operation of the generator, as well as possible enrichment. The cooling medium in the condenser and absorber is done by the ambient air with a temperature at 35 °C. Helium is used as inert gas. The total pressure in the cycle is about 17.5 bars. We used suitable software to modulate for the two binary following the system propylene /butane and propylene/pentane. Our model is validated by comparison with the literature’s resultants.

Keywords: absorption, DAR cycle, diffusion, propyléne

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Authors: Joanna Bajerska, Agata Chmurzyńska, Agata Muzsik, Patrycja Krzyżanowska, Klaudia Łochocka, Jarosław Walkowiak

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The Mediterranean diet (MED) is regarded as beneficial in the therapy of central obesity-associated metabolic abnormalities. However, in the traditional diet of the Central European countries, food items with positive nutritional profiles (rye bread, oats, buckwheat, herrings, linseed and rapeseed oil, berries, apples, plums, root vegetables etc.) are also used. We hypothesized that the Central European Diet (CED) may be comparatively effective in reducing symptoms of central obesity as MED. We tested the health effects of the CED, which is an environmentally friendly regional diet and the traditional MED diet in a group of postmenopausal centrally obese women. A total 58 with a mean age of 60 y (50-70y), body mass index (in kg/m(2)) of 33.4 (22.6-47.3), and waist circumference of 105 cm (87.5-137 cm) were randomly assigned to receive either the diet based on food items commonly used in Central Europe (the CED group; n = 29) or the Mediterranean diet (the MED group; n = 29) for 15 weeks. Body mass and body composition were measured with a Bod Pod (Cosmed, Italy). A non-elastic flexible measuring tape was used to measure waist circumference. Additionally, blood pressure, plasma lipid and glucose levels were assessed with the use of a biochemical analyzer. A total of 50 subjects [86% (CED 83%; MED 90%)] completed the intervention. A high dietary compliance for both described diets was achieved. The mean (±SEM) weight and waist circumference changes were -7.4 ± 0.7 kg; -8.3 ± 0.7 cm and -8.1 ± 0.5 kg; -7.1 ± 0.6 cm for the CED and MED groups, respectively. Moreover, there were no differences between the effectiveness of the diets used in terms of the influence on fat mass, blood pressure, and biochemical parameters. The preliminary data suggest that both described diets may be successfully used for improving central obesity-associated metabolic abnormalities. The project was financed by the National Science Centre awarded based on the number of decision DEC-013/09/B/NZ9/02365

Keywords: central european diet, central obesity, Mediterranean diet, metabolic abnormalities

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Authors: R. Bhattu Babajee, Marie Sandrine Estelle Benoit

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The past decades have witnessed a considerable institutional shift towards Central Bank Independence across economies of the world. The motivation behind such a change is the acceptance that increased central bank autonomy has the power of alleviating inflation bias. Hence, studying whether Central Bank Independence acts as a significant factor behind the price stability in the African economies or whether this macroeconomic aim in these countries result from other economic, political or social factors is a pertinent issue. The main research objective of this paper is to assess the relationship between central bank autonomy and inflation in African economies where inflation has proved to be a serious problem. In this optic, we shall measure the degree of CBI in Africa by computing the turnover rates of central banks governors thereby studying whether decisions made by African central banks are affected by external forces. The purpose of this study is to investigate empirically the association between Central Bank Independence (CBI) and inflation for 10 African economies over a period of 17 years, from 1995 to 2012. The sample includes Botswana, Egypt, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Nigeria, South Africa, and Uganda. In contrast to empirical research, we have not been using the usual static panel model for it is associated with potential mis specification arising from the absence of dynamics. To this issue a dynamic panel data model which integrates several control variables has been used. Firstly, the analysis includes dynamic terms to explain the tenacity of inflation. Given the confirmation of inflation inertia, that is very likely in African countries there exists the need for including lagged inflation in the empirical model. Secondly, due to known reverse causality between Central Bank Independence and inflation, the system generalized method of moments (GMM) is employed. With GMM estimators, the presence of unknown forms of heteroskedasticity is admissible as well as auto correlation in the error term. Thirdly, control variables have been used to enhance the efficiency of the model. The main finding of this paper is that central bank independence is negatively associated with inflation even after including control variables.

Keywords: central bank independence, inflation, macroeconomic variables, price stability

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Authors: Reza Eka Putra

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Pamsimas is a community based drinking water supply and sanitation program which is contributed by local community, local government, central government, and World Bank with the aim of achieving Water Supply and Sanitation - the Millennium Development Goals (WSS-MDGs) target. This program is supported by the Ministry of Public Works as the executing agency with the cooperation of Ministry of Interior and the Ministry of Health. Field observations were conducted in two rural samples of 2009 beneficiaries Pamsimas West Java, which is in Ponggang Village, Subang District. The study was evaluated through several parameters, including technical, health, and empowerment aspect. Evaluation was done by comparing the parameters of success that has been set by Pamsimas through Pamsimas book manuals with the parameters from Sanitation & Infrastructure course regarding the appropriate application of technology in society. The result of the study is that the potency of the community before the program is implemented in the village is the determining factor. Stronger cooperation pattern in Ponggang Vilage results in a successful program. Both villages showed a pattern of behavior changes from indiscriminate defecation to sanitary latrine use. Besides, there is a decline in the number of cases of diarrheal disease since the year of Pamsimas implementation.

Keywords: millenium development goals, community develpoment, water supply, sanitation

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Authors: Hosein Faramarzpour

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This work presents the optimum operational conditions for a hydrogen-based micro-scale power source, using a verified mathematical model including fluid dynamics and reaction kinetics. Thereafter the stable operational flame regime is pursued as a key factor in optimizing the design of micro-combustors. The results show that with increasing velocities, four H2 flame regimes develop in the micro-combustor, namely: 1) periodic ignition-extinction regime, 2) steady symmetric regime, 3) pulsating asymmetric regime, and 4) steady asymmetric regime. The first regime that appears in 0.8 m/s inlet velocity is a periodic ignition-extinction regime which is characterized by counter flows and tulip-shape flames. For flow velocity above 0.2 m/s, the flame shifts downstream, and the combustion regime switches to a steady symmetric flame where temperature increases considerably due to the increased rate of incoming energy. Further elevation in flow velocity up to 1 m/s leads to the pulsating asymmetric flame formation, which is associated with pulses in various flame properties such as temperature and species concentration. Further elevation in flow velocity up to 1 m/s leads to the pulsating asymmetric flame formation, which is associated with pulses in various flame properties such as temperature and species concentration. Ultimately, when the inlet velocity reached 1.2 m/s, the last regime was observed, and a steady asymmetric regime appeared.

Keywords: thermophotovoltaic generator, micro combustor, micro power generator, combustion regimes, flame dynamic

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Authors: Chul Ho Han, Kyoung Hoon Kim

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This paper carries out a performance analysis based on the first and second laws of thermodynamics for heat recovery vapor generator (HRVG) of ammonia-water mixture when the heat source is low-temperature energy in the form of sensible heat. In the analysis, effects of the ammonia mass concentration and mass flow ratio of the binary mixture are investigated on the system performance including the effectiveness of heat transfer, entropy generation, and exergy efficiency. The results show that the ammonia concentration and the mass flow ratio of the mixture have significant effects on the system performance of HRVG.

Keywords: entropy, exergy, ammonia-water mixture, heat exchanger

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Authors: Maibigue Nanglet, Arafat Ousman Béchir, Mahamat Hassan Béchir

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The economy of Central African countries is growing very fast, and the demand for energy is increasing every day. As a result, insufficient power generation is one of the major problems slowing down development. This paper explores the factors of degradation of the I-V curve of the PV Generator (GPV) in harsh environments, taking the case of two locals: Mongo and Abeche. Its objective is to quantify the voltage leaks due to the different GPV installation areas; after using the Newton-Raphson numerical method of the solar cell, a survey of several experimental measurement points was made. The results of the simulation in MATLAB/Simulink show a relative power loss factor of 11.8765% on the GPVs installed in Mongo and 8.5463% on those installed in Abeche; these results allow us to say that the supports on which the modules are installed have an average impact of 10.2114% on their efficiency.

Keywords: calculation, degradation, site, GPV, severe environment

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Authors: Yili Chen, Xiaokun Liang, Zhicheng Zhang, Yaoqin Xie

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In an effort to restore visual perception in retinal diseases, an electronic retinal prosthesis with thousands of electrodes has been developed. The image processing strategies of retinal prosthesis system converts the original images from the camera to the stimulus pattern which can be interpreted by the brain. Practically, the original images are with more high resolution (256x256) than that of the stimulus pattern (such as 25x25), which causes a technical image processing challenge to do large-capacity image information reduction. In this paper, we focus on developing an efficient image processing stimulus pattern extraction algorithm by using a single cue saliency map for extracting salient objects in the image with an optimal trimming threshold. Experimental results showed that the proposed stimulus pattern extraction algorithm performs quite well for different scenes in terms of the stimulus pattern. In the algorithm performance experiment, our proposed SCSPE algorithm have almost five times of the score compared with Boyle’s algorithm. Through experiment s we suggested that when there are salient objects in the scene (such as the blind meet people or talking with people), the trimming threshold should be set around 0.4max, in other situations, the trimming threshold values can be set between 0.2max-0.4max to give the satisfied stimulus pattern.

Keywords: retinal prosthesis, image processing, region of interest, saliency map, trimming threshold selection

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Authors: I. Shuro

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The crystal structure of Tin Sulfide prepared by certain chemical methods is investigated using High-Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) methods. An anomalous HRTEM Fast Fourier Transform (FFT) exhibited a central scatter of diffraction spots, which is surrounded by secondary clusters of spots arranged in a hexagonal pattern around the central cluster was observed. FFT analysis has revealed a long lattice parameter and mostly viewed along a hexagonal axis where there many columns of atoms slightly displaced from one another. This FFT analysis has revealed that the metal sulfide has a long-range order interwoven chain of atoms in its crystal structure. The observed crystalline structure is inconsistent with commonly observed FFT patterns of chemically synthesized Tin Sulfide nanocrystals and thin films. SEM analysis showed the morphology of a myriad of multi-shaped crystals ranging from hexagonal, cubic, and spherical micro to nanostructured crystals. This study also investigates the presence of quasi-crystals as reflected by the presence of mixed local symmetries.

Keywords: fast fourier transform, high resolution transmission electron microscopy, tin sulfide, crystalline structure

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Authors: E. Bounadja, M. O. Mahmoudi, A. Djahbar, Z. Boudjema

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This paper presents a control approach of the doubly fed induction generator (DFIG) in conjunction with a direct AC-AC matrix converter used in generating mode. This device is intended to be implemented in a variable speed wind energy conversion system connected to the grid. Firstly, we developed a model of matrix converter, controlled by the Venturini modulation technique. In order to control the power exchanged between the stator of the DFIG and the grid, a control law is synthesized using a high order sliding mode controller. The use of this method provides very satisfactory performance for the DFIG control. The overall strategy has been validated on a 2-MW wind turbine driven a DFIG using the Matlab/Simulink.

Keywords: doubly fed induction generator (DFIG), matrix converter, high-order sliding mode controller, wind energy

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Authors: K. Jithendra Gowd, Ch. Sai Babu, S. Sivanagaraju

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Electric power systems are daily exposed to service interruption mainly due to faults and human accidental interference. Short circuit currents are responsible for several types of disturbances in power systems. The fault currents are high and the voltages are reduced at the time of fault. This paper presents two suitable methods, consideration of fault resistance and Distributed Generator are implemented and analyzed for the enhancement of voltage profile during fault conditions. Fault resistance is a critical parameter of electric power systems operation due to its stochastic nature. If not considered, this parameter may interfere in fault analysis studies and protection scheme efficiency. The effect of Distributed Generator is also considered. The proposed methods are tested on the IEEE 37 bus test systems and the results are compared.

Keywords: distributed generation, electrical distribution systems, fault resistance

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Authors: Dilek Ozlem Esen, Mesut Kaya

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The focus of this study is to analyse the results of heat recovery from exhaust gas which is produced by an internal combustion engine (ICE). To obtain a small amount of energy, an exhaust system which is suitable for recovery waste heat has been constructed. Totally 27 TEGs have been used to convert from the heat to electric energy. By producing a small amount of this energy by the help of thermoelectric generators can reduce engine loads thus decreasing pollutant emissions, fuel consumption, and CO2. This case study is conducted in an effort to better understand and improve the performance of thermoelectric heat recovery systems for automotive use. As a result of this study, 0,45 A averaged current rate, 13,02 V averaged voltage rate and 5,8 W averaged electrical energy have been produced in a five hours operation time.

Keywords: thermoelectric, peltier, thermoelectric generator (TEG), exhaust, cogeneration

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Authors: Mahmoud Huleihil

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In this study, the performance of a thermodynamic gas cycle of magnetohydrodynamic (MHD) power generation is considered and presented in terms of power efficiency curves. The dissipation mechanisms considered include: fluid friction modeled by means of the isentropic efficiency of the compressor, heat transfer leakage directly from the hot reservoir to the cold heat reservoir, and constant velocity of the MHD generator. The study demonstrates that power and efficiency vanish at the extremes of both slow and fast operating conditions. These points are demonstrated on power efficiency curves and the locus of efficiency at maximum power and the locus of maximum efficiency. Qualitatively, the considered loss mechanisms have a similar effect on the efficiency at maximum power operation and on maximum efficiency operation, thus these efficiencies are reduced, even for small values of the loss mechanisms.

Keywords: magnetohydrodynamic generator, electrical efficiency, maximum power, maximum efficiency, heat engine

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Authors: Roman Snytsar

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Pseudo-random numbers are often used in scientific computing such as the Monte Carlo Simulations or the Quantum Inspired Optimization. Requirements for a parallel random number generator running in the modern multi-core vector environment are more stringent than those for sequential random number generators. As well as passing the usual quality tests, the output of the parallel random number generator must be verifiable and reproducible throughout the concurrent execution. We propose a family of vectorized Permuted Congruential Generators. Implementations are available for multiple modern vector modern computer architectures. Besides demonstrating good single core performance, the generators scale easily across many processor cores and multiple distributed nodes. We provide performance and parallel speedup analysis and comparisons between the implementations.

Keywords: pseudo-random numbers, quantum optimization, SIMD, parallel computing

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Authors: A. El Kachani, E. Chakir, A. Ait Laachir, A. Niaaniaa, J. Zerouaoui

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This document presents an adaptive controller based on recursive parametric identification applied to a wind turbine based on the doubly-fed induction machine (DFIG), to compensate the faults and guarantee efficient of the DFIG. The proposed adaptive controller is based on the recursive least square algorithm which considers that the best estimator for the vector parameter is the vector x minimizing a quadratic criterion. Furthermore, this method can improve the rapidity and precision of the controller based on a model. The proposed controller is validated via simulation on a 5.5 kW DFIG-based wind turbine. The results obtained seem to be good. In addition, they show the advantages of an adaptive controller based on recursive least square algorithm.

Keywords: adaptive controller, recursive least squares algorithm, wind turbine, doubly fed induction generator

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Authors: Andrea Catorci, Federico Maria Tardella, Alessandro Brica, Muhammad Umair

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Climate change models predict for the Mediterranean region a strong increase of intensity and frequency of drought events, with an expected effect on grassland biodiversity and functioning. The research aim was to understand how the grassland species modulate their resource acquisition and conservation strategies to short-term variation of the pattern of summer water supply. The study area is mountain meadows located in the ‘‘Montagna di Torricchio’’ (1130 m a.s.l.) a Nature Reserve in central Italy. In 2017 we started a manipulative experiment for 2 year (2017-2018), and we defined two treatments, one with increasing water (watering condition) and the other with less water (drought condition). Then, we investigated how species change their resource strategies at different amount of water availability by measuring the specific leaf area (SLA) and leaf area (LA). We used ANOVAs to test the effect of treatment over time on leaf area and specific leaf area, considering all the species together and also separately according to their growth form (forb, grass, legume). Our results showed that species may respond differently depending on their growth form and that using all the species together may cover more detailed variation. Overall, resource retaining strategies (lower SLA, LA) are resulted by increase of drought condition, while increase in water amount and number of watering events fosters acquisitive strategies (higher SLA, LA). However, this pattern is not constant for all growth form. Grass species are able to maintain their strategies to variation of the pattern of water availability. Forb and legume species on the other side have shown decreasing trend of SLA, LA values with increasing drought condition, a pattern more marked for the latter growth form. These variations suggest not only an increase of slow-growing strategies for both growth form, but also a decrease of their nutrient pastoral values since their leaves are supposed to become harder. Local farmers should consider the effect of climate change on grassland and adapt their management practices to guarantee the cattle welfare.

Keywords: function strategies, grasslands, climate change, sub Mediterranean region

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Authors: M. Pramila Devi, N. V. N. Indra Kiran

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Control charts, predominantly in the form of X-bar chart, are important tools in statistical process control (SPC). They are useful in determining whether a process is behaving as intended or there are some unnatural causes of variation. A process is out of control if a point falls outside the control limits or a series of point’s exhibit an unnatural pattern. In this paper, a study is carried out on four training algorithms for CCPs recognition. For those algorithms optimal structure is identified and then they are studied for type I and type II errors for generalization without early stopping and with early stopping and the best one is proposed.

Keywords: control chart pattern recognition, neural network, backpropagation, generalization, early stopping

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Authors: L. Hassaine, A. Mraoui, M. R. Bengourina

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In photovoltaic system, connected to the grid, the main goal is to control the power that the inverter injects into the grid from the energy provided by the photovoltaic generator. This paper proposes a control technique for a photovoltaic system connected to the grid based on the digital pulse-width modulation (DSPWM) which can synchronise a sinusoidal current output with a grid voltage and generate power at unity power factor. This control is based on H-Bridge inverter controlled by bipolar PWM Switching. The electrical scheme of the system is presented. Simulations results of output voltage and current validate the impact of this method to determinate the appropriate control of the system. A digital design of a generator PWM using VHDL is proposed and implemented on a Xilinx FPGA.

Keywords: grid connected photovoltaic system, H-Bridge inverter, control, bipolar PWM

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Authors: S. Krustev, V. Angelova, K. Ivanov, P. Zaprjanova

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Approximately a dozen trace elements are vital for the development of all plants and some other elements are significant for some species. Heavy metals do not belong to this group of elements that are essential to plants, but some of them such as copper and zinc, have a dual effect on their growth. Concentration levels of these elements in the different regions of the world vary considerably. Their high concentrations in some parts of Central and Eastern Europe cause concern for human health and degrade the quality of agricultural produce from these areas. This study aims to compare the prevalence and levels of the major trace elements in some rural areas of Central and Eastern Europe. Soil samples from different regions of the Czech Republic, Slovakia, Austria, Hungary, Serbia, Romania, Bulgaria and Greece far from large industrial centers have been studied. The main methods for their determination are the atomic spectral techniques – atomic absorption and plasma atomic emission. As a result of this study, data on microelements levels in soils of 17 points from the main grain-producing regions of Central and Eastern Europe are presented and systematized. The content of trace elements was in the range of 5.0-84.1 mg.kg⁻¹ for Cu, 0.3-1.4 mg.kg⁻¹ for Cd, 26.1-225.5 mg.kg⁻¹ for Zn, 235.5-788.6 mg.kg⁻¹ for Mn and 4.1-25.8 mg.kg⁻¹ for Pb.

Keywords: trace elements, heavy metals, agricultural soils, Central and Eastern Europe

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Authors: Thanaporn Chaimongkol

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The objective of this research was aimed to examine the factors that influence the development of community leadership strategies to further develop the career regarding the Benjarong pottery products in eight upper central provinces, Thailand. The sample included (1) 1200 Benjarong pottery operators, (2) 30 involved representatives at both the policy level and support, and (3) OTOP network of 24 people. In this quantitative study, investigating data was conducted on individual session basis. The research instruments used included questionnaires and interview. The results showed that the components of the development of the community leadership strategies for career development of the Benjarong pottery products in eight upper central provinces were high overall; the Five Competitive Forces were of the highest average, followed by bargaining power of suppliers, and McKinsey 7's framework, respectively; where the highest average was strategy.

Keywords: community leadership, strategy development, Benjarong Pottery, 8 upper central provinces

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Authors: Yulong Wang, Yuan Yan Tang, Cuiming Zou, Lina Yang

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This paper presents a novel sparse representation method for robust pattern classification. Generalized orthogonal matching pursuit (GOMP) is a recently proposed efficient sparse representation technique. However, GOMP adopts the mean square error (MSE) criterion and assign the same weights to all measurements, including both severely and slightly corrupted ones. To reduce the limitation, we propose an information-theoretic GOMP (ITGOMP) method by exploiting the correntropy induced metric. The results show that ITGOMP can adaptively assign small weights on severely contaminated measurements and large weights on clean ones, respectively. An ITGOMP based classifier is further developed for robust pattern classification. The experiments on public real datasets demonstrate the efficacy of the proposed approach.

Keywords: correntropy induced metric, matching pursuit, pattern classification, sparse representation

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Authors: Sadiq J. Abou-Loukh, Hanan M. Habbi

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This paper presents a steganography to hide the transmitted information without excite suspicious and also illustrates the level of secrecy that can be increased by using cryptography techniques. The proposed system has been implemented firstly by encrypted image file one time pad key and secondly encrypted message that hidden to perform encryption followed by image embedding. Then the new image file will be created from the original image by using four triangles operation, the new image is processed by one of two image processing techniques. The proposed two processing techniques are thresholding and differential predictive coding (DPC). Afterwards, encryption or decryption keys are generated by functional key generator. The generator key is used one time only. Encrypted text will be hidden in the places that are not used for image processing and key generation system has high embedding rate (0.1875 character/pixel) for true color image (24 bit depth).

Keywords: encryption, thresholding, differential predictive coding, four triangles operation

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Authors: N. Zerzouri, N. Benalia, N. Bensiali

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During recent years wind turbine technology has undergone rapid developments. Growth in size and the optimization of wind turbines has enabled wind energy to become increasingly competitive with conventional energy sources. As a result today’s wind turbines participate actively in the power production of several countries around the world. These developments raise a number of challenges to be dealt with now and in the future. The penetration of wind energy in the grid raises questions about the compatibility of the wind turbine power production with the grid. In particular, the contribution to grid stability, power quality and behavior during fault situations plays therefore as important a role as the reliability. In the present work, we addressed two fault situations that have shown their influence on the generator and the behavior of the wind over the defects which are briefly discussed based on simulation results.

Keywords: doubly fed induction generator (DFIG), wind energy, grid fault, electrical engineering

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Authors: Abd Al-Salam Al-Masgari, Haylay Tsegab, Ismailalwali Babikir, Monera A. Shoieb

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We present a study of Malaysia's Central Luconia region, which is an essential deposit of Miocene carbonate reservoirs. This study aims to identify and map areas of selected carbonate platforms, develop high-resolution statistical karst models, and generate comprehensive karst geobody models for selected carbonate fields. This study uses seismic characterization and advanced geophysical surveys to identify karst signatures in Miocene carbonate reservoirs. The results highlight the use of variance, RMS, RGB colour blending, and 3D visualization Prop seismic sequence stratigraphy seismic attributes to visualize the karstified areas across the F23 field of Central Luconia. The offshore karst model serves as a powerful visualization tool to reveal the karstization of carbonate sediments of interest. The results of this study contribute to a better understanding of the karst distribution of Miocene carbonate reservoirs in Central Luconia, which are essential for hydrocarbon exploration and production. This is because these features significantly impact the reservoir geometry, flow path and characteristics.

Keywords: karst, central Luconia, seismic attributes, Miocene carbonate build-ups

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Authors: Ya-Chi Yu, Pei-Syuan Ruan, Shao-Wen Chen, Yu-Hsien Chang, Jin-Der Lee, Jong-Rong Wang, Chunkuan Shih

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This study analyzed the transient signals of central region void fraction of air-water two-phase flow in a 3x3 rod bundle. Experimental tests were carried out utilizing a vertical rod bundle test section along with a set of air-water supply/flow control system, and the transient signals of the central region void fraction were collected through the electrical conductivity sensors as well as visualized via high speed photography. By converting the electric signals, transient void fraction can be obtained through the voltage ratios. With a fixed superficial water velocity (J_f=0.094 m/s), two different superficial air velocities (J_g=0.094 m/s and 0.236 m/s) were tested and presented, which were corresponding to the flow conditions of bubbly flows and cap/slug flows, respectively. The time averaged central region void fraction was obtained as 0.109-0.122 with 0.028 standard deviation for the selected bubbly flow and 0.188-0.221with 0.101 standard deviation for the selected cap/slug flow, respectively. Through Fast Fourier Transform (FFT) analysis, no clear frequency peak was found in bubbly flow, while two dominant frequencies were identified around 1.6 Hz and 2.5 Hz in the present cap/slug flow.

Keywords: central region, rod bundles, transient void fraction, two-phase flow

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Authors: A. Bouchakour, L. Zaghba, M. Brahami, A. Borni

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The work presented in this paper present the design and the simulation of a centrifugal pump coupled to a photovoltaic (PV) generator via a MPPT controller. The PV system operating is just done in sunny period by using water storage instead of electric energy storage. The process concerns the modelling, identification and simulation of a photovoltaic pumping system, the centrifugal pump is driven by an asynchronous three-phase voltage inverter sine triangle PWM motor through. Two configurations were simulated. For the first, it is about the alimentation of the motor pump group from electrical power supply. For the second, the pump unit is connected directly to the photovoltaic panels by integration of a MPPT control. A code of simulation of the solar pumping system was initiated under the Matlab-Simulink environment. Very convivial and flexible graphic interfaces allow an easy use of the code and knowledge of the effects of change of the sunning and temperature on the pumping system.

Keywords: photovoltaic generator, chopper, electrical motor, centrifugal pump

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Authors: Shankaran Sitarama

Abstract:

New Product Development (NPD) is invariably a team effort and involves effective teamwork. NPD team has members from different disciplines coming together and working through the different phases all the way from conceptual design phase till the production and product roll out. Creativity and Innovation are some of the key factors of successful NPD. Team members going through the different phases of NPD interact and work closely yet challenge each other during the design phases to brainstorm on ideas and later converge to work together. These two traits require the teams to have a divergent and a convergent thinking simultaneously. There needs to be a good balance. The team dynamics invariably result in conflicts among team members. While some amount of conflict (ideational conflict) is desirable in NPD teams to be creative as a group, relational conflicts (or discords among members) could be detrimental to teamwork. Team communication truly reflect these tensions and team dynamics. In this research, team communication (emails) between the members of the NPD teams is considered for analysis. The email communication is processed through a semantic analysis algorithm (LSA) to analyze the content of communication and a semantic similarity analysis to arrive at a social network graph that depicts the communication amongst team members based on the content of communication. The amount of communication (content and not frequency of communication) defines the interaction strength between the members. Social network adjacency matrix is thus obtained for the team. Standard social network analysis techniques based on the Adjacency Matrix (AM) and Dichotomized Adjacency Matrix (DAM) based on network density yield network graphs and network metrics like centrality. The social network graphs are then rendered for visual representation using a Metric Multi-Dimensional Scaling (MMDS) algorithm for node placements and arcs connecting the nodes (representing team members) are drawn. The distance of the nodes in the placement represents the tie-strength between the members. Stronger tie-strengths render nodes closer. Overall visual representation of the social network graph provides a clear picture of the team’s interactions. This research reveals four distinct patterns of team interaction that are clearly identifiable in the visual representation of the social network graph and have a clearly defined computational scheme. The four computational patterns of team interaction defined are Central Member Pattern (CMP), Subgroup and Aloof member Pattern (SAP), Isolate Member Pattern (IMP), and Pendant Member Pattern (PMP). Each of these patterns has a team dynamics implication in terms of the conflict level in the team. For instance, Isolate member pattern, clearly points to a near break-down in communication with the member and hence a possible high conflict level, whereas the subgroup or aloof member pattern points to a non-uniform information flow in the team and some moderate level of conflict. These pattern classifications of teams are then compared and correlated to the real level of conflict in the teams as indicated by the team members through an elaborate self-evaluation, team reflection, feedback form and results show a good correlation.

Keywords: team dynamics, team communication, team interactions, social network analysis, sna, new product development, latent semantic analysis, LSA, NPD teams

Procedia PDF Downloads 55

Authors: Fitria D. Ayuningtyas, Anggraini Barlian

Abstract:

Green turtle (Chelonia mydas) is one of TSD (Temperature-dependent Sex Determination, TSD) animals which sex is determined by the egg’s incubation temperature. GSD (Genotypic Sex Determination) homologous genes such as Wilms’ Tumor (Wt1) and Forkhead Box L2 (FoxL2) play a role in TSD animal sex determination process. Wt1 plays a role in both male pathway, as a transcription factor for Sf1 gene and in female pathway, as a transcription factor for Dax1. FoxL2 plays a role specifically in female sex determination, and known as transcriptional factor for Aromatase gene. Until now, research on the pattern of Wt1 and FoxL2 genes expression in C.mydas has not been conducted yet. The aim of this research is to know the pattern of Wt1 and FoxL2 genes expression in Mesonephros-Gonad (MG) complexes of Chelonia mydas embryos incubated in masculinizing temperature (MT) and feminizing temperature (FT). Eggs of C.mydas incubated in 3 different stage of TSP (Thermosensitive Period) at masculinizing temperature (26±10C, MT) and feminizing temperature (31±10C FT). Mesonefros-gonad complexes were isolated at Pre-TSP stage (FT at days 14th, MT at days 24th), TSP stage (FT at days 24th, MT at days 36th) and differentiated stage (FT at days 40th, MT at days 58th). RNA from mesonephros-gonad (MG) complexes were converted into cDNA by RT-PCR process, and the pattern of Wt1 and FoxL2 genes expression is analyzed by quantitative Real Time PCR (qPCR) method, β-actin gene is used as an internal control. The pattern of Wt1 gene expression in Pre-TSP stage was almost the same between MG complexes incubated at MT or FT, while TSP and differentiation stage, the pattern of Wt1 gene expression in MG complexes incubated at MT or FT was increased. Wt1 gene expression of MG complexes that incubated at FT was higher than at MT. There was a difference pattern between Wt1 gene expression in this research compared to the previous research in protein level. It could be assumed that the difference caused by post-transcriptional regulation mechanisms before mRNA of Wt1 gene translated into protein structure. The pattern of FoxL2 gene expression in Pre-TSP stage was almost the same between MG complexes that incubated at MT and FT, and increased in both TSP and differentiated stage. The FoxL2 gene expression in MG complexes that incubated in FT is higher than MT on TSP and differentiated stage. Based on the results of this research, it can be assumed that Wt1 and FoxL2 gene were expressed in MG complexes that incubated both at MT and FT since Pre-TSP stage. The pattern of Wt1 gene expression was increased in every stage of gonadal development, and so do the pattern of FoxL2 gene expression. Wt1 and FoxL2 gene expressions were higher in MG complexes incubated at FT than MT.

Keywords: chelonia mydas, FoxL2, gene expression, TSD, Wt1

Procedia PDF Downloads 394

Authors: Jiranun Sreecharit, Anongnat Boonrut, Kunvadee Munvaradee, Phechnoy Singchungchai

Abstract:

Hatyai Hospital as center of hospital with a capacity of 670 beds. Medicine intensive care units (MICU240) provide care for critically ill patients who are at high risk need to be monitored closely. Intravenous catheter is vital to help assess the level of water in the body fluids and medications. Potential complications such as infection. We need to have guidelines for the care of patients who received intravenous catheter used to achieve good results. The operations research in this study was intended 1) To study the effects of practice for nurses in caring for patients with central venous catheter to infection rate and 2) To assess the satisfaction of nurses and patient care practices in central venous catheterization patients in the MICU 240. The sample of the patient's central venous catheter crisis that everyone who admitted in MICU 240 during the period from October 2013 to May 2014. Samples prior to practice and 148 samples with 249 case of practice. A systematic review of the research NSWHealth Statewide Guideline for Intensive Care. Data were analyzed by statistics, percentages and frequency NON-PARAMETRICS with Mann-Whitney U. The finding revealed that: 1. Results of the practice patient care central venous catheter infection rates were found to be reduced from 35.14 percent to 25.3 percent. 2. The results of the evaluation of nurses and patients in the patient care practices central venous catheter found to be satisfied and happy to work 85 percent.

Keywords: clinical practice guidelines, central venous catheter, infection satisfaction

Procedia PDF Downloads 468