Search results for: Joule effect
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 4593

Search results for: Joule effect

2553 Simulation of Propagation of Cos-Gaussian Beam in Strongly Nonlocal Nonlinear Media Using Paraxial Group Transformation

Authors: A. Keshavarz, Z. Roosta

Abstract:

In this paper, propagation of cos-Gaussian beam in strongly nonlocal nonlinear media has been stimulated by using paraxial group transformation. At first, cos-Gaussian beam, nonlocal nonlinear media, critical power, transfer matrix, and paraxial group transformation are introduced. Then, the propagation of the cos-Gaussian beam in strongly nonlocal nonlinear media is simulated. Results show that beam propagation has periodic structure during self-focusing effect in this case. However, this simple method can be used for investigation of propagation of kinds of beams in ABCD optical media.

Keywords: Paraxial group transformation, nonlocal nonlinear media, Cos-Gaussian beam, ABCD law.

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2552 Proposed Program for Developing Some Concepts for Nursery School Children in Egypt Using Artistic Activities

Authors: Ebtehag Tolba

Abstract:

The study presents a proposed program for nursery school children in Egypt. The program consists of a collection of artistic activities and aims to develop the language, mathematical, and artistic skills of preschool children. Furthermore, the researcher has presented a questionnaire to experts about the link between the target group and the content. Finally, the proposed program was applied to group of 30 children. In addition, the researcher has prepared another questionnaire for measuring the effect of the program. This questionnaire was used as a pre-test and post-test, and at the end of the study, a significant difference was determined in favour of the post-test results.

Keywords: Developing, concepts, nursery, children, artistic activities.

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2551 Does Labour Supply Respond to Globalisation? Malaysia Evidence from Micro Data

Authors: Poo Bee Tin, Rahmah Ismail, Norasmah Othman

Abstract:

Globalisation is a phenomenon that cannot be avoided. As globalisation allowed free flow of inputs including labour, it may affect job opportunities for the locals. Therefore, investigate the determinants of labour supply is essential in understanding the structure of labour market in the new era of globalization. The objective of this article is to examine labour supply by taking into account the globalisation effect. The study covers 3885 households in Peninsular Malaysia who are chosen using stratified random sampling. The labour supply model will be the basis for the analysis. The basic labour supply determinants are own wage and non-labour income. However, the extended labour supply model incorporates other variables like spouse wage,number of children and individuals characteristics like education level and age. Besides, the globalization indicator will also be incorporated as another independent variable.

Keywords: globalization, head of households, labour supply, wage

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2550 Towards Self-ware via Swarm-Array Computing

Authors: Blesson Varghese, Gerard McKee

Abstract:

The work reported in this paper proposes Swarm-Array computing, a novel technique inspired by swarm robotics, and built on the foundations of autonomic and parallel computing. The approach aims to apply autonomic computing constructs to parallel computing systems and in effect achieve the self-ware objectives that describe self-managing systems. The constitution of swarm-array computing comprising four constituents, namely the computing system, the problem/task, the swarm and the landscape is considered. Approaches that bind these constituents together are proposed. Space applications employing FPGAs are identified as a potential area for applying swarm-array computing for building reliable systems. The feasibility of a proposed approach is validated on the SeSAm multi-agent simulator and landscapes are generated using the MATLAB toolkit.

Keywords: Swarm-Array computing, Autonomic computing, landscapes.

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2549 Performance Analysis of a Free-Space Optical Code Division Multiple Access through Atmospheric Turbulence Channel

Authors: Tanveer Ahmed Bhuiyan, Samiul Hayder Choudhury, Asif Al - Rasheed, S.P. Majumder

Abstract:

In this paper, the effect of atmospheric turbulence on bit error probability in free-space optical CDMA scheme with Sequence Inverse Keyed (SIK) optical correlator receiver is analyzed. Here Intensity Modulation scheme is considered for transmission. The turbulence induced fading is described by the newly introduced gamma-gamma pdf[1] as a tractable mathematical model for atmospheric turbulence. Results are evaluated with Gold and Kasami code & it is shown that Gold sequence can be used for more efficient transmission than Kasami sequence in an atmospheric turbulence channel.

Keywords: CDMA, gamma-gamma pdf, atmospheric turbulence, Kasami, Gold, SIK, BER, Power Penalty, FSO.

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2548 Analysis of FWM Penalties in DWDM Systems Based on G.652, G.653, and G.655 Optical Fibers

Authors: Paula B. Harboe, Edilson da Silva, José R. Souza

Abstract:

This paper presents an investigation of the power penalties imposed by four-wave mixing (FWM) on G.652 (Single- Mode Fiber - SMF), G.653 (Dispersion-Shifted Fiber - DSF), and G.655 (Non-Zero Dispersion-Shifted Fiber - NZDSF) compliant fibers, considering the DWDM grids suggested by the ITU-T Recommendations G.692, and G.694.1, with uniform channel spacing of 100, 50, 25, and 12.5 GHz. The mathematical/numerical model assumes undepleted pumping, and shows very clearly the deleterious effect of FWM on the performance of DWDM systems, measured by the signal-to-noise ratio (SNR). The results make it evident that non-uniform channel spacing is practically mandatory for WDM systems based on DSF fibers.

Keywords: DWDM systems, Four-Wave Mixing (FWM), G.652, G.653, G.655 compliant fibers, Signal-to-noise ratio.

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2547 Improved Power Spectrum Estimation for RR-Interval Time Series

Authors: B. S. Saini, Dilbag Singh, Moin Uddin, Vinod Kumar

Abstract:

The RR interval series is non-stationary and unevenly spaced in time. For estimating its power spectral density (PSD) using traditional techniques like FFT, require resampling at uniform intervals. The researchers have used different interpolation techniques as resampling methods. All these resampling methods introduce the low pass filtering effect in the power spectrum. The lomb transform is a means of obtaining PSD estimates directly from irregularly sampled RR interval series, thus avoiding resampling. In this work, the superiority of Lomb transform method has been established over FFT based approach, after applying linear and cubicspline interpolation as resampling methods, in terms of reproduction of exact frequency locations as well as the relative magnitudes of each spectral component.

Keywords: HRV, Lomb Transform, Resampling, RR-intervals.

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2546 An Experimental Study of the Effect of Coil Step on Heat Transfer Coefficient in Shell- Side of Shell-and-Coil Heat Exchanger

Authors: Mofid Gorji Bandpy, Hasan Sajjadi

Abstract:

In this study the mixed convection heat transfer in a coil-in-shell heat exchanger for various Reynolds numbers and various dimensionless coil pitch was experimentally investigated. The experiments were conducted for both laminar and turbulent flow inside coil and the effects of coil pitch on shell-side heat transfer coefficient of the heat exchanger were studied. The particular difference in this study in comparison with the other similar studies was the boundary conditions for the helical coils. The results indicate that with the increase of coil pitch, shell-side heat transfer coefficient is increased.

Keywords: Coil pitch, Shell-and-Coil heat exchanger, Mixed convection, Experimental investigation.

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2545 Effect of Personalization on Students' Achievement and Gender Factor in Mathematics Education

Authors: Nurettin Simsek, Özlem Cakır

Abstract:

The aim of this study is to point out whether personalization of mathematical word problems could affect student achievement or not. The research was applied on two-grades students at spring semester 2008-2009. Before the treatment, students personal data were taken and given to the computer. During the treatment, paper-based personalized problems and paper-based non personalized problems were prepared by computer as the same problems and then these problems were given to students. At the end of the treatment, students- opinion was taken. As a result of this research, it was found out that there were no significant differences between learners through personalized or non-personalized materials, and also there were no significant differences between gender through personalized and non-personalized problems. However, opinion of students was highly positive through the personalized problems.

Keywords: Personalization, word problem, computer aided personalization.

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2544 Analytical Model Prediction: Micro-Cutting Tool Forces with the Effect of Friction on Machining Titanium Alloy (Ti-6Al-4V)

Authors: Mohd Shahrom Ismail, B.T. Hang Tuah Baharudin, K.K.B. Hon

Abstract:

In this paper, a methodology of a model based on predicting the tool forces oblique machining are introduced by adopting the orthogonal technique. The applied analytical calculation is mostly based on Devries model and some parts of the methodology are employed from Amareggo-Brown model. Model validation is performed by comparing experimental data with the prediction results on machining titanium alloy (Ti-6Al-4V) based on micro-cutting tool perspective. Good agreements with the experiments are observed. A detailed friction form that affected the tool forces also been examined with reasonable results obtained.

Keywords: dynamics machining, micro cutting tool, Tool forces

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2543 Grounded Theory of Consumer Loyalty, a Perspective through Video Game Addiction

Authors: Bassam Shaikh, R. S. A. Jumain

Abstract:

Game addiction has become an extremely important topic in psychology researchers, particularly in understanding and explaining why individuals become addicted (to video games). In previous studies, effect of online game addiction on social responsibilities, health problems, government action, and the behaviors of individuals to purchase and the causes of making individuals addicted on the video games has been discussed. Extending these concepts in marketing, it could be argued than the phenomenon could enlighten and extending our understanding on consumer loyalty. This study took the Grounded Theory approach, and found that motivation, satisfaction, fulfillments, exploration and achievements to be part of the important elements that builds consumer loyalty.

Keywords: Consumer Loyalty, Video Games Addiction, Video Games, Grounded Theory.

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2542 The Effect of Solution Density on the Synthesis of Magnesium Borate from Boron-Gypsum

Authors: N. Tugrul, E. Sariburun, F. T. Senberber, A. S. Kipcak, E. Moroydor Derun, S. Piskin

Abstract:

Boron-gypsum is a waste which occurs in the boric acid production process. In this study, the boron content of this waste is evaluated for the use in synthesis of magnesium borates and such evaluation of this kind of waste is useful more than storage or disposal. Magnesium borates, which are a sub-class of boron minerals, are useful additive materials for the industries due to their remarkable thermal and mechanical properties. Magnesium borates were obtained hydrothermally at different temperatures. Novelty of this study is the search of the solution density effects to magnesium borate synthesis process for the increasing the possibility of borongypsum usage as a raw material. After the synthesis process, products are subjected to XRD and FT-IR to identify and characterize their crystal structure, respectively.

Keywords: Boron-gypsum, hydrothermal synthesis, magnesium borate, solution density.

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2541 Optimal Resource Configuration and Allocation Planning Problem for Bottleneck Machines and Auxiliary Tools

Authors: Yin-Yann Chen, Tzu-Ling Chen

Abstract:

This study presents the case of an actual Taiwanese semiconductor assembly and testing manufacturer. Three major bottleneck manufacturing processes, namely, die bond, wire bond, and molding, are analyzed to determine how to use finite resources to achieve the optimal capacity allocation. A medium-term capacity allocation planning model is developed by considering the optimal total profit to satisfy the promised volume demanded by customers and to obtain the best migration decision among production lines for machines and tools. Finally, sensitivity analysis based on the actual case is provided to explore the effect of various parameter levels.

Keywords: Capacity planning, capacity allocation, machine migration, resource configuration.

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2540 Active Cyber Defense within the Concept of NATO’s Protection of Critical Infrastructures

Authors: Serkan Yağlı, Selçuk Dal

Abstract:

Cyber attacks pose a serious threat to all states. Therefore, states constantly seek for various methods to encounter those threats. In addition, recent changes in the nature of cyber attacks and their more complicated methods have created a new concept: active cyber defense (ACD). This article tries to answer firstly why ACD is important to NATO and find out the viewpoint of NATO towards ACD. Secondly, infrastructure protection is essential to cyber defense. Critical infrastructure protection with ACD means is even more important. It is assumed that by implementing active cyber defense, NATO may not only be able to repel the attacks but also be deterrent. Hence, the use of ACD has a direct positive effect in all international organizations’ future including NATO.

Keywords: Active cyber defense, advanced persistent treat, critical infrastructure, NATO.

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2539 Gamma Irradiation Effects on the Magnetic Properties of Hard Ferrites

Authors: F. Abbas Pour Khotbehsara, B. Salehpour, A. Kianvash

Abstract:

Many industrial materials like magnets need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large influences of beta, neutron and gamma’s over their life Gamma irradiation of the permanent sample magnets using a 60Co source was investigated up to an absorbed dose of 700Mrad shows a negligible effect on some magnetic properties of Nd-Fe-B. In this work it has been tried to investigate the change of some important properties of Barium hexa ferrite. Results showed little decreases of magnetic properties at doses rang of 0.5 to 2.5 Mrad. But at the gamma irradiation dose up to 10 Mrad it is showed a few increase of properties. Also study of gamma irradiation of Nd-Fe-B showed considerably increase of magnetic properties.

Keywords: Gamma ray irradiation, Hard Ferrite, Magnetic coefficient, Radiation dose.

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2538 E-Voting: A Trustworthiness In Democratic; A View from Technology, Political and Social Issue

Authors: Sera Syarmila Sameon, Rohaini Ramli

Abstract:

A trustworthy voting process in democratic is important that each vote is recorded with accuracy and impartiality. The accuracy and impartiality are tallied in high rate with biometric system. One of the sign is a fingerprint. Fingerprint recognition is still a challenging problem, because of the distortions among the different impression of the same finger. Because of the trustworthy of biometric voting technologies, it may give a great effect on numbers of voter-s participation and outcomes of the democratic process. Hence in this study, the authors are interested in designing and analyzing the Electronic Voting System and the participation of the users. The system is based on the fingerprint minutiae with the addition of person ID number. This is in order to enhance the accuracy and speed of the voting process. The new design is analyzed by conducting pilot election among a class of students for selecting their representative.

Keywords: Biometric, FAR and FRR, democratic, voting

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2537 Angles of Arrival Estimation with Unitary Partial Propagator

Authors: Youssef Khmou, Said Safi

Abstract:

In this paper, we investigated the effect of real valued transformation of the spectral matrix of the received data for Angles Of Arrival estimation problem.  Indeed, the unitary transformation of Partial Propagator (UPP) for narrowband sources is proposed and applied on Uniform Linear Array (ULA).

Monte Carlo simulations proved the performance of the UPP spectrum comparatively with Forward Backward Partial Propagator (FBPP) and Unitary Propagator (UP). The results demonstrates that when some of the sources are fully correlated and closer than the Rayleigh angular limit resolution of the broadside array, the UPP method outperforms the FBPP in both of spatial resolution and complexity.

Keywords: DOA, Uniform Linear Array, Narrowband, Propagator, Real valued transformation, Subspace, Unitary Operator.

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2536 Research on Regional Energy Saving Potential Based on Nonparametric Radial Adjustment and Slack Adjustment

Authors: Donglan Zha, Ning Ding

Abstract:

Taking the provincial capital, labor and energy as inputs, regional GDP as output from 1995 to 2007, the paper quantifies the vertical and lateral energy saving potential by introducing the radial adjustment and slack adjustment of DEA. The results show that by the vertical, the achievement of energy saving in 2007 is better than their respective historical performances. By horizontal, in 2007 it can be found that Tianjin, Liaoning, Shanghai and Yunnan do better in energy saving than other provinces. In national wide, the higher of energy efficiency, the larger of per capita GDP and the proportion of the tertiary industry in the national economy, the more open to the outside, the lower the energy saving potential demonstrates, while the energy endowment has negative effect on energy saving potential.

Keywords: radial adjustment; slack adjustment; regional disparity; energy saving potential

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2535 Vector Control Using Series Iron Loss Model of Induction, Motors and Power Loss Minimization

Authors: Kheldoun Aissa, Khodja Djalal Eddine

Abstract:

The iron loss is a source of detuning in vector controlled induction motor drives if the classical rotor vector controller is used for decoupling. In fact, the field orientation will not be satisfied and the output torque will not truck the reference torque mostly used by Loss Model Controllers (LMCs). In addition, this component of loss, among others, may be excessive if the vector controlled induction motor is driving light loads. In this paper, the series iron loss model is used to develop a vector controller immune to iron loss effect and then an LMC to minimize the total power loss using the torque generated by the speed controller.

Keywords: Field Oriented Controller, Induction Motor, Loss ModelController, Series Iron Loss.

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2534 Investigation of Behavior on the Contact Surface of the Tire and Ground by CFD Simulation

Authors: M. F. Sung, Y.D. Kuan, R.J. Shyu, S.M. Lee

Abstract:

Tread design has evolved over the years to achieve the common tread pattern used in current vehicles. However, to meet safety and comfort requirements, tread design considers more than one design factor. Tread design must consider the grip and drainage, and the manner in which to reduce rolling noise, which is one of the main factors considered by manufacturers. The main objective of this study was the application the computational fluid dynamics (CFD) technique to simulate the contact surface of the tire and ground. The results demonstrated an air-Pumping and large pressure drop effect in the process of contact surface. The results also revealed that the pressure can be used to analyze sound pressure level (SPL).

Keywords: Air-pumping, computational fluid dynamics, sound pressure level, tire.

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2533 Restoration of Noisy Document Images with an Efficient Bi-Level Adaptive Thresholding

Authors: Abhijit Mitra

Abstract:

An effective approach for extracting document images from a noisy background is introduced. The entire scheme is divided into three sub- stechniques – the initial preprocessing operations for noise cluster tightening, introduction of a new thresholding method by maximizing the ratio of stan- dard deviations of the combined effect on the image to the sum of weighted classes and finally the image restoration phase by image binarization utiliz- ing the proposed optimum threshold level. The proposed method is found to be efficient compared to the existing schemes in terms of computational complexity as well as speed with better noise rejection.

Keywords: Document image extraction, Preprocessing, Ratio of stan-dard deviations, Bi-level adaptive thresholding.

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2532 Forced Vibration of a Fiber Metal Laminated Beam Containing a Delamination

Authors: Sh. Mirhosseini, Y. Haghighatfar, M. Sedighi

Abstract:

Forced vibration problem of a delaminated beam made of fiber metal laminates is studied in this paper. Firstly, a delamination is considered to divide the beam into four sections. The classic beam theory is assumed to dominate each section. The layers on two sides of the delamination are constrained to have the same deflection. This hypothesis approves the conditions of compatibility as well. Consequently, dynamic response of the beam is obtained by the means of differential transform method (DTM). In order to verify the correctness of the results, a model is constructed using commercial software ABAQUS 6.14. A linear spring with constant stiffness takes the effect of contact between delaminated layers into account. The attained semi-analytical outcomes are in great agreement with finite element analysis.

Keywords: Delamination, forced vibration, finite element modelling, natural frequency.

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2531 Soil Mass Loss Reduction during Rainfalls by Reinforcing the Slopes with the Surficial Confinement

Authors: Ramli Nazir, Hossein Moayedi

Abstract:

Soil confinement systems serve as effective solutions to any erosion control project. Various confinements systems, namely triangular, circular and rectangular with the size of 50, 100, and 150 mm, and with a depth of 10 mm, were embedded in soil samples at slope angle of 60°. The observed soil mass losses for the confined soil systems were much smaller than those from unconfined system. As a result, the size of confinement and rainfall intensity have a direct effect on the soil mass loss. The triangular and rectangular confinement systems showed the lowest and highest soil loss masses, respectively. The slopes also failed much faster in the unconfined system than in the confined slope.

Keywords: Erosion control, Soil confinement, Soil erosion, Slope stability.

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2530 Influence of Turbulence Model, Grid Resolution and Free-Stream Turbulence Intensity on the Numerical Simulation of the Flow Field around an Inclined Flat Plate

Authors: M. Raciti Castelli, P. Cioppa, E. Benini

Abstract:

The flow field around a flat plate of infinite span has been investigated for several values of the angle of attack. Numerical predictions have been compared to experimental measurements, in order to examine the effect of turbulence model and grid resolution on the resultant aerodynamic forces acting on the plate. Also the influence of the free-stream turbulence intensity, at the entrance of the computational domain, has been investigated. A full campaign of simulations has been conducted for three inclination angles (9°, 15° and 30°), in order to obtain some practical guidelines to be used for the simulation of the flow field around inclined plates and discs.

Keywords: CFD, lift, drag, flat plate

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2529 Production and Mechanical Characterization of Ballistic Thermoplastic Composite Materials

Authors: D. Korsacilar, C. Atas

Abstract:

In this study, first thermoplastic composite materials /plates that have high ballistic impact resistance were produced. For this purpose, the thermoplastic prepreg and the vacuum bagging technique were used to produce a composite material. Thermoplastic prepregs (resin-impregnated fiber) that are supplied ready to be used, namely high-density polyethylene (HDPE) was chosen as matrix and unidirectional glass fiber was used as reinforcement. In order to compare the fiber configuration effect on mechanical properties, unidirectional and biaxial prepregs were used. Then the microstructural properties of the composites were investigated with scanning electron microscopy (SEM) analysis. Impact properties of the composites were examined by Charpy impact test and tensile mechanical tests and then the effects of ultraviolet irradiation were investigated on mechanical performance.

Keywords: Ballistic, Composite, Thermoplastic.

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2528 Effect of Flow Holes on Heat Release Performance of Extruded-type Heat Sink

Authors: Jung Hyun Kim, Gyo Woo Lee

Abstract:

In this study, the enhancement of the heat release performance of an extruded-type heat sink to prepare the large-capacity solar inverter thru the flow holes in the base plate near the heat sources was investigated. Optimal location and number of the holes in the baseplate were determined by using a commercial computation program. The heat release performance of the shape-modified heat sink was measured experimentally and compared with that of the simulation. The heat sink with 12 flow holes in the 18-mm-thick base plate has a 8.1% wider heat transfer area, a 2.5% more mass flow of air, and a 2.7% higher heat release rate than those of the original heat sink. Also, the surface temperature of the base plate was lowered 1.5oC by the holes.

Keywords: Heat Sink, Forced Convection, Heat Transfer, Performance Evaluation, Flow Holes.

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2527 Inhibition on Conidial Germination of Colletotrichum gloeosporiodes and Pestalotiopsis eugeniae by Bacillus subtilis LB5

Authors: Onuma Ruangwong, Wen-Jinn Liang, S.Y. Zhang, Chi-I Chang

Abstract:

The effect of antifungal compound from Bacillus subtilis strain LB5 was tested against conidial germination of Colletotrichum gloeosporioides and Pestalotiopsis eugeniae, causal agent of anthracnose and fruit rot of wax apple, respectively. Observation under scanning electron microscope and light compound microscope revealed that conidial germination was completely inhibited when treated with culture broth, culture filtrate, or crude extract from strain LB5. Identification of purified antifungal compound produced by strain LB5 in cell-free supernatant by nuclear magnetic resonance and fast atom bombardment showed that the active compound was iturin A-2.

Keywords: Iturin A-2, Bacillus subtilis LB5, Colleteotrichum gloeospporioides, Pestalotiopsis eugeniae, wax apple

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2526 Modified Techniques for Distribution System Reliability Improvement by Parallel Operation of Transformers

Authors: Ohn Zin Lin, Okka, Cho Cho Myint

Abstract:

It is important to consider the effects of transformers on distribution system because they have the highest impact on system reliability. It is generally said that parallel operation of transformers (POT) can improve the system reliability. However, the estimation approach can be also considered for accuracy. In this paper, we propose a three-state components model and equations to determine the reliability improvement by POT, and cooperation of POT and distributed generation (DG). Based on the proposed model and techniques, the effect of POT is analyzed in four different tests with the consideration of conventional distribution system, distribution automation system (DAS) and DG. According to the results, the reliability is greatly improved by cooperation of POT, DAS and DG. The proposed model and methods are applicable to not only developing countries which have conventional distribution system but also developed countries in which DAS has already installed.

Keywords: Distribution system, reliability, dispersed generator, energy not supply, transformer parallel operation.

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2525 Effects of Macrophyte Vallisneria asiatica Biomasses on the Algae Community

Authors: Caixia Kang, Takahiro Kuba, Aimin Hao, Yasushi Iseri, Chunjie Li, Zhenjia Zhang

Abstract:

To improve the water quality of lakes and control algae blooms, the effects of Vallisneria asiatica which is one of aquatic plants spread over Lake Taihu, with different biomasses on the water quality and algae communities were researched. The results indicated that V. asiatica could control an excess of Microcystis spp. when the V. asiatica biomass was larger than 50g in the tank with 30L solution in the laboratory. Planktonic and epiphytic algae responded differently to V. asiatica. The presence of macrophyte V. asiatica in eutrophic waters has a positive effect on algae compositions because of different sensitivities of algae species to allelopathic substances released by macrophyte V. asiatica. That is, V. asiatica could inhibit the growth of Microcystis spp. effectively and was benefited to the diatom on the condition in the laboratory.

Keywords: Algae bloom, algae community, Microcystis spp., Vallisneria asiatica.

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2524 Influence and Interaction of Temperature, H2S and pH on Concrete Sewer Pipe Corrosion

Authors: Anna Romanova, Mojtaba Mahmoodian, Morteza A. Alani

Abstract:

Concrete sewer pipes are known to suffer from a process of hydrogen sulfide gas induced sulfuric acid corrosion. This leads to premature pipe degradation, performance failure and collapses which in turn may lead to property and health damage. The above work reports on a field study undertaken in working sewer manholes where the parameters of effluent temperature and pH as well as ambient temperature and concentration of hydrogen sulfide were continuously measured over a period of two months. Early results suggest that effluent pH has no direct effect on hydrogen sulfide build up; on average the effluent temperature is 3.5°C greater than the ambient temperature inside the manhole and also it was observed that hydrogen sulfate concentration increases with increasing temperature.

Keywords: Concrete corrosion, hydrogen sulphide gas, temperature, sewer pipe.

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