Search results for: production control

Authors: Ananya Rajagopal

Abstract:

The study is based on an analysis of qualitative data used to analyze the business performance of entrepreneurs in emerging markets based on core variables such as collective leadership in reference to social entrepreneurship and reverse accountability attributes of stakeholders. In-depth interviews were conducted with 25 emerging enterprises within Mexico across five industrial segments. The study has been conducted focusing on five major research questions, which helped in developing the grounded theory related to reverser accountability. The results of the study revealed that the traditional entrepreneurship model based on an individualistic leadership style is being replaced by a collective leadership model. The study focuses on the leadership styles within social enterprises aimed at enhancing managerial capabilities and competencies, stakeholder values, and entrepreneurial growth. The theoretical motivation of this study has been derived from stakeholder theory and agency theory.

Keywords: reverse accountability, social enterprises, collective leadership, grounded theory, social governance

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Authors: Megh Patel, Arjun Chauhan, Jay Thakkar

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Hydrofracturing is the most prominent but at the same time expensive, highly skilled and time consuming well stimulation technique. Due to high cost and skilled labor involved, it is generally carried out as the consummate solution among other well stimulation techniques. Considering today’s global petroleum market, no gaffe or complications could be entertained during fracturing, as it would further hamper the current dwindling economy. The literature would be dealing with the challenges encountered during fracturing low temperature waxy reservoirs and the prominent solutions to overcome such teething troubles. During fracturing treatment for, shallow and high freezing point waxy oil reservoirs, the first line problems are to overcome uncompleted breakdown, uncompleted cleanup of fracturing fluids and cold damages to the formations by injecting cold fluid (fluid at ambient conditions). Injecting fracturing fluids at ambient conditions have the tendency to decrease the near wellbore reservoir temperature below the freezing point of oil reservoir and hence leading to wax deposition around the wellbore thereby hampering the fluid production as well as fracture propagation. To overcome such problems, solutions such as hot fracturing fluid injection, encapsulated heat generating hydraulic fracturing fluid system, and injection of wax inhibitor techniques would be discussed. The paper would also be throwing light on changes in rheological properties occurred during heating fracturing fluids and solutions to deal with it taking economic considerations into account.

Keywords: hydrofracturing, waxy reservoirs, low temperature, viscosity, crosslinkers

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Authors: Riaan Kleyn

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Mass wine production companies across the globe are provided with grapes from winegrowers that predominantly utilize mechanical harvesting machines to harvest wine grapes. Mechanical harvesting accelerates the rate at which grapes are harvested, allowing grapes to be delivered faster to meet the demands of wine cellars. The disadvantage of the mechanical harvesting method is the inclusion of material-other-than-grapes (MOG) in the harvested wine grape loads arriving at the cellar which degrades the quality of wine that can be produced. Currently, wine cellars do not have a method to determine the amount of MOG present within wine grape loads. This paper seeks to find an optimal computer vision method capable of detecting the amount of MOG within a wine grape load. A MOG detection method will encourage winegrowers to deliver MOG-free wine grape loads to avoid penalties which will indirectly enhance the quality of the wine to be produced. Traditional image segmentation methods were compared to deep learning segmentation methods based on images of wine grape loads that were captured at a wine cellar. The Mask R-CNN model with a ResNet-50 convolutional neural network backbone emerged as the optimal method for this study to determine the amount of MOG in an image of a wine grape load. Furthermore, a statistical analysis was conducted to determine how the MOG on the surface of a grape load relates to the mass of MOG within the corresponding grape load.

Keywords: computer vision, wine grapes, machine learning, machine harvested grapes

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Authors: Alireza Toloei, Ahmad R. Saffary, Reza Ghasemi

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Due to the growing need for energy and limited fossil resources, the use of renewable energy, particularly wind is strongly favored. We all wind energy can’t be saved. Betz law, 59% of the total kinetic energy of the wind turbine is extracting. Therefore turbine control to achieve maximum performance and maintain stable conditions seem necessary. In this article, we plan for a horizontal axis wind turbine variable-speed variable-pitch nonlinear controller to obtain maximum output power. The model presented in this article, including a wide range of wind turbines are horizontal axis. However, the parameters used in this model is from Vestas V29 225 kW wind turbine. We designed second order sliding mode controller, which was robust in the face of changes in wind speed and it eliminated chattering by using of super twisting algorithm. Finally, using MATLAB software to simulate the results we considered the accuracy of the simulation results.

Keywords: non linear controller, robust, sliding mode, kinetic energy

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Authors: R. Ziaie Moayed, S. P. Emadoleslami Oskoei, S. D. Beladi Mousavi, A. Taleb Beydokhti

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There have been many reports of the destructive effects of cement on the environment in recent years. In the present research, it has been attempted to reduce the destructive effects of cement by replacing silica fume as adhesive materials instead of cement. The present study has attempted to improve the mechanical properties of cement slurry by using waste material from a glass production factory, located in Qazvin city of Iran, in which accumulation volume has become an environmental threat. The chemical analysis of the waste material indicates that this material contains about 94% of SiO₂ and AL₂O₃ and has a close structure to silica fume. Also, the particle grain size test was performed on the mentioned waste. Then, the unconfined compressive strength test of the slurry was performed by preparing a mixture of water and adhesives with different percentages of cement and silica fume. The water to an adhesive ratio of this mixture is 1:3, and the curing process last 28 days. It was found that the sample had an unconfined compressive strength of about 300 kg/cm² in a mixture with equal proportions of cement and silica fume. Besides, the sample had a brittle fracture in the slurry sample made of pure cement, however, the fracture in cement-silica fume slurry mixture is flexible and the structure of the specimen remains coherent after fracture. Therefore, considering the flexibility that is achieved by replacing this waste, it can be used to stabilize soils with cracking potential.

Keywords: cement replacement, cement slurry, environmental threat, natural pozzolan, silica fume, waste material

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Authors: Barenten Suciu, Yoshiki Tsuji

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In this paper, a theoretical investigation on the dynamic characteristics of one degree of freedom vibration system equipped with inerter of variable inertance, is presented. Differential equation of movement was solved under proper initial conditions in the case of free undamped/damped vibration, considered in the absence/presence of the inerter in the mechanical system. Influence of inertance on the amplitude of vibration, phase angle, natural frequency, damping ratio, and logarithmic decrement was clarified. It was mainly found that the inerter decreases the natural frequency of the undamped system and also of the damped system if the damping ratio is below 0.707. On the other hand, the inerter increases the natural frequency of the damped system if the damping ratio exceeds 0.707. Results obtained in this work are useful for the adequate design of inerters.

Keywords: damping, frequency control, inerter, one degree of freedom vibration system, parallel connection, variable inertance

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Authors: Sanaz Kavianpour, Zuraini Ismail, Bharanidharan Shanmugam

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Social Network Sites (SNSs) can be served as an invaluable platform to transfer the information across a large number of individuals. A substantial component of communicating and managing information is to identify which individual will influence others in propagating information and also whether dissemination of information in the absence of social signals about that information will be occurred or not. Classifying the final audience of social data is difficult as controlling the social contexts which transfers among individuals are not completely possible. Hence, undesirable information diffusion to an unauthorized individual on SNSs can threaten individuals’ privacy. This paper highlights the information diffusion in SNSs and moreover it emphasizes the most significant privacy issues to individuals of SNSs. The goal of this paper is to propose a privacy-preserving model that has urgent regards with individuals’ data in order to control availability of data and improve privacy by providing access to the data for an appropriate third parties without compromising the advantages of information sharing through SNSs.

Keywords: anonymization algorithm, classification algorithm, information diffusion, privacy, social network sites

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Authors: Arun Das

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One of the basic objectives of Independent India five decades ago was to meet the increasing demand for food to its growing population. Self-sufficiency was accomplished towards food production and it was attained through launching green revolution program. The green revolution repercussions were not realized at that moment. Many projects were undertaken. Especially, major and minor irrigation projects were executed to harness the river water in the dry land regions of Karnataka. In the elevated topographical lands, extraction of underground water was a solace given by the government to protect the interest of the dry land farmers whose land did not come under the command area. Free borewell digging, pump sets, and electricity were provided. Thus, the self-sufficiency was achieved. Contrary to this, the Continuous long-term extraction of water for agriculture from bore well and in the irrigated tracks has lead to two-way effect such as soil leeching (Alkalinity and Salinity), secondly, depleted underground water to incredible deeps has pushed the natural process to an un-reparable damage which in turn the nature lost to support even a tiny plants like grass to grow, discouraging human and animal habitation, Both the process is silently turning southwestern, central, northeastern and north western regions of Karnataka into desert. The grave situation of Karnataka green revolution is addressed in this paper to alert reckless use of water and also some of the suggestions are recommended based on the ground information.

Keywords: alkalinity, desertification, green revolution, salinity, water

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Authors: J.Das, Gyan Wrat

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Leakage is the main gradual failure in the fluid power system, which is usually caused by the impurity in the oil and wear of matching surfaces between parts and lead to the change of the gap value. When leakage occurs in the system, the oil will flow from the high pressure chamber into the low pressure chamber through the gap, causing the reduction of system flow as well as the loss of system pressure, resulting in the decreasing of system efficiency. In the fluid power system, internal leakage may occur in various components such as gear pump, reversing valve and hydraulic cylinder, and affect the system work performance. Therefore, component leakage in the fluid power system is selected as the study to characterize the leakage and the effect of leakage on the system. Effect of leakage on system pressure and cylinder displacement can be obtained using pressure sensors and the displacement sensor. The leakage can be varied by changing the orifice using a flow control valve. Hydraulic circuit for leakage will be developed in Matlab/Simulink environment and simulations will be done by changing different parameters.

Keywords: leakage causes, effect, analysis, MATLAB simulation, hydraulic circuit

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Authors: F. Z. Mahi, H. Marinchio, C. Palermo, L. Varani

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We propose an analytical approach for the admittance response calculation of the high mobility InGaAs channel transistors. The development of the small-signal admittance takes into account the longitudinal and transverse electric fields through a pseudo two-dimensional approximation of the Poisson equation. The total currents and the potentials matrix relation between the gate and the drain terminals determine the frequency-dependent small-signal admittance response. The analytical results show that the admittance spectrum exhibits a series of resonant peaks corresponding to the excitation of plasma waves. The appearance of the resonance is discussed and analyzed as functions of the channel length and the temperature. The model can be used, on one hand, to control the appearance of plasma resonances, and on the other hand, can give significant information about the admittance phase frequency dependence.

Keywords: small-signal admittance, Poisson equation, currents and potentials matrix, the drain and the gate terminals, analytical model

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Authors: Lucas Aerre, Wallesson Faria, Roberto Pimentel, Juliana Santos

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An extremely disturbing and irritating element in the lives of people and organizations is the noise, the consequences that can bring us has a lot of connection with human health as well as financial and economic aspects. In order to improve the efficiency of buildings in Brazil in general, a performance standard was created, NBR 15.575 in which all buildings are seen in a more systemic and peculiar way, while following the requirements of the standard. The acoustic performance present in these buildings is one such requirement. Based on this, the present work was elaborated with the objective of evaluating through acoustic measurements the acoustic performance of vertical internal fences that are under the incidence of aerial noise of a building in the city of Brasilia-DF. A short theoretical basis is made and soon after the procedures of measurement are described through the control method established by the standard, and its results are evaluated according to the parameters of the same. The measurement performed between rooms of the same unit, presented a standardized sound pressure level difference (D nT, w) equal to 40 dB, thus being classified within the minimum performance required by the standard in question.

Keywords: airborne noise, performance standard, soundproofing, vertical seal

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Authors: Rodrigo Coelho

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We believe that in the majority of the “recent production of public space", the overvaluation of the "image", of the "ephemeral" and of the "objectual", has come to determine the configuration of banal and (more or less) arbitrary "public spaces", mostly linked to a problem of “outdoor decoration”, reflecting a clear sign of uncertainty and arbitrariness about the meaning, the role and shape of public space and public art.This "inconsistency" which is essentially linked to the loss of urban, but also social, cultural and political, vocation of the disciplines that “shape” the urban space (but is also linked to the lack of urban and technical culture of techinicians and policy makers) converted a significant set of the recently built "public space" and “urban art” into diffuse and multi-referenced pieces, which generally shares the inability of confering to the urban space, civic, aesthetic, social and symbolic meanings. In this sense we consider it is essential to undertake a theoretical reflection on the values, the meaning(s) and the shape(s) that open space, and urban art may (or must) take in the current urban and cultural context, in order to redeem for public space its status of significant physical reference, able to embody a spatial and urban identity, and simultaneously enable the collective accession and appropriation of public space. Taking as reference public space interventions built in the last decade on the European context, we will seek to explore and defend the need of considering public space as a true place of exception, an exceptional support where the emphasis is placed on the quality of the experience, especially by the relations public space/urban art can established with the city, with nature and geography in a broad sense, referring us back to a close and inseparable and timeless relationship between nature and culture.

Keywords: art, city, nature, public space

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Authors: I. Mentziou, C. Delezos, A. Nestoridou, G. Boskou

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Introduction: The system of production and distribution of meals can have a significant impact on the food intake of hospital patients who are likely to develop malnutrition. In hospitals, the consequences of food borne infections can range from annoying to life-threatening for a patient, since they can lead up to death in vulnerable groups. Aim: The aim of the present study was to evaluate the satisfaction of the patients from the food services in Greek hospitals. Methods: Eleven hospitals of the Attica region were chosen. The sample derived from 637 adult patients who were hospitalized in those hospitals, during the period September 2009 - April 2010. Tailor made questionnaires were used to interview patients upon their satisfaction from the current food service system as well as from the total quality management system of the hospital. The number of completed questionnaires was proportional to the hospital capacity. Results: The majority of the patients seem to be pleased from the quality and the variety of the meals; they judged positively the behaviour of the food service personnel and the hygiene of serving conditions. Patients made suggestions for more frequent meals, larger variety of choices and better presented meals served under proper hygiene conditions by the personnel. Conclusions: The results indicate that the patients are satisfied in regards to the meal choices and the serving methods. However, factors like temperature and hygiene conditions are not always perceived to be in a way that fulfills the necessary prerequisite requirements. A total quality management system as a driver for better patient satisfaction is Indispensable.

Keywords: evaluation, food service, HACCP, hospital, patients

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Authors: Warunpun Kongsom, Chaiwat Kongsom

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The objective of this study was to investigate the awareness, knowledge and consumer behavior towards organic products in Thailand. For this study, a purposive sampling technique was used to identify a sample group of 2,575 consumers over the age of 20 years who intended or made purchases from 1) green shops; 2) supermarkets with branches; and, 3) green markets. A questionnaire was used for data collection across the country. Descriptive statistics were used for data analysis. The results showed that more than 92% of consumers were aware of organic agriculture, but had less knowledge about it. More than 60% of consumers knew that organic agriculture production and processing did not allow the use of chemicals. And about 40% of consumers were confused between the food safety logo and the certified organic logo, and whether GMO was allowed in organic agriculture practice or not. In addition, most consumers perceived that organic agricultural products, good agricultural practice (GAP) products, agricultural chemicals free products, and hydroponic vegetable products had the same standard. In the view of organic consumers, the organic Thailand label was the most seen and reliable among various organic labels. Less than 3% of consumers thought that the International Federation of Organic Agriculture Movements (IFOAM) Global Organic Mark (GOM) was the most seen and reliable. For the behaviors of organic consumers, they purchased organic products mainly at the supermarket and green shop (55.4%), one to two times per month, and with a total expenditure of about 200 to 400 baht each time. The main reason for buying organic products was safety and free from agricultural chemicals. The considered factors in organic product selection were price (29.5%), convenience (22.4%), and a reliable certification system (21.3%). The demands for organic products were mainly rice, vegetables and fruits. Processed organic products were relatively small in quantity.

Keywords: consumer behavior, consumer knowledge, organic products, Thailand

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Authors: Amara Rafik, Bougherara Maamar, Belhadj Aissa Mostefa

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Radar data is one of the many data sources used by ATM Air Traffic Management systems. These data come from air navigation radar antennas. These radars intercept signals emitted by the various aircraft crossing the controlled airspace and calculate the position of these aircraft and retransmit their positions to the Air Traffic Management System. For greater reliability, these radars are positioned in such a way as to allow their coverage areas to overlap. An aircraft will therefore be detected by at least one of these radars. However, the position coordinates of the same aircraft and sent by these different radars are not necessarily identical. Therefore, the ATM system must calculate a single position (radar track) which will ultimately be sent to the control position and displayed on the air traffic controller's monitor. There are several techniques for calculating the radar track. Furthermore, the geographical nature of the problem requires the use of a Geographic Information System (GIS), i.e. a geographical database on the one hand and geographical processing. The objective of this work is to propose a GIS for traffic simulation which reconstructs the evolution over time of aircraft positions from a multi-source radar data set and by applying these different techniques.

Keywords: ATM, GIS, radar data, air traffic simulation

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Authors: D. Zahraddeen, N. M. Lemu, P. P. Barje, I. S. R. Butswat

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This study was conducted to investigate some of the factors affecting the optimum reproductive capacity of the indigenous breeds of sheep in Nigeria. A total of 767 sheep of different breeds were investigated. The reproductive indices considered were birth/weaning weights, litter size, parity, mortality, reproductive problems/disorders, body condition score (BCS), as well as growth traits. The results showed that litter size, parity, and BCS had significant (p < 0.05) effects on birth/weaning weights, mortality rates and growth traits of the sheep breeds studied. Similarly, the rearing method/system significantly (p < 0.05) influenced other reproductive traits such as birth/weaning weights, mortality, growth performance of lambs. However, the major reproductive problems/disorders in the ewes were dystocia (30.94%), retained placenta (16.91%), mastitis (15.83), pregnancy toxaemia (11.51%), uterine prolapse (6.48%) and vaginal prolapse (3.24%). In the rams, the incidence of reproductive problems included cryptorchidism (1.08%), orchitis (2.87%) and scrotal dermatophilosis (1.79%), among others. This study concludes that the four breeds of sheep (Balami, Yankasa, Uda, and West African Dwarf sheep) and their crosses exhibited varied genetic make-up and potentials. However, the large number of sheep farmers practicing the extensive production system might be responsible for the low reproductive performance of this species in the country. It is, therefore, recommended that significant improvement could be achieved through enhanced management practices of these animals.

Keywords: sheep, breeds, reproduction, disorders

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Authors: Anthony Iyenjamu, Josiah Adeyemo

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Due to the increasing water scarcity in South Africa, the prime focus of irrigation in South Africa shifts to creating feasible water sources and the efficient use of these sources. These irrigation systems in South Africa are implemented because of low and erratic rainfall and high evaporative demand. Irrigation contributes significantly to crop production in South Africa, as the mean annual precipitation for the country is usually less than 500mm. This is considered to be the minimum required for rain fed cropping. Even though the rainfall is low, a lot of the water in various areas in South Africa is lost due to runoff into storm water systems that run to the rivers and eventually into the sea. This study reviews the irrigation systems in South Africa which can be vastly improved by creating irrigation dams. A method of which may seem costly at first but rewarding with time. The study investigates the process of creating dam capacity capable of sustaining a suitable area size of land to be irrigated and thus diverting all runoff into these dams. This type of infrastructure method vastly improves various sectors in our irrigation systems. Extensive research is carried out in the surrounding area in which the dam should be constructed. Rainfall patterns and rainfall data is used for calculations of which period the dam will be at its optimum using rainfall. The size of the area irrigated was used to calculate the size of the irrigation dam to be constructed. The location of the dam must be situated as close to the river as possible to minimize the excessive use of pipelines to the dam. This study also investigated all existing resources to alleviate the cost. It was found that irrigation dams could solve the erratic distribution of rainfall in South Africa for irrigation purposes.

Keywords: irrigation, rainfed, rain harvesting, reservoir

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Authors: R. Hellmuth, F. Wehner

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Factory planning has the task of designing products, plants, processes, organization, areas, and the construction of a factory. The requirements for factory planning and the building of a factory have changed in recent years. Regular restructuring is becoming more important in order to maintain the competitiveness of a factory. Restrictions in new areas, shorter life cycles of product and production technology as well as a VUCA world (Volatility, Uncertainty, Complexity & Ambiguity) lead to more frequent restructuring measures within a factory. A digital factory model is the planning basis for rebuilding measures and becomes an indispensable tool. Short-term rescheduling can no longer be handled by on-site inspections and manual measurements. The tight time schedules require up-to-date planning models. Due to the high adaptation rate of factories described above, a methodology for rescheduling factories on the basis of a modern digital factory twin is conceived and designed for practical application in factory restructuring projects. The focus is on rebuild processes. The aim is to keep the planning basis (digital factory model) for conversions within a factory up to date. This requires the application of a methodology that reduces the deficits of existing approaches. The aim is to show how a digital factory model can be kept up to date during ongoing factory operation. A method based on photogrammetry technology is presented. The focus is on developing a simple and cost-effective solution to track the many changes that occur in a factory building during operation. The method is preceded by a hardware and software comparison to identify the most economical and fastest variant. 

Keywords: digital factory model, photogrammetry, factory planning, restructuring

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Authors: Faezeh Aghazadeh, Mohammad Javad Sharifi

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The application of neural networks to model a full-scale industrial acetylene hydrogenation in olefin plant has been studied. The operating variables studied are the, input-temperature of the reactor, output-temperature of the reactor, hydrogen ratio of the reactor, [C₂H₂]input, and [C₂H₆]input. The studied operating variables were used as the input to the constructed neural network to predict the [C₂H₆]output at any time as the output or the target. The constructed neural network was found to be highly precise in predicting the quantity of [C₂H₆]output for the new input data, which are kept unaware of the trained neural network showing its applicability to determine the [C₂H₆]output for any operating conditions. The enhancement of [C₂H₆]output as compared with [C₂H₆]input was a consequence of low selective acetylene hydrogenation to ethylene.

Keywords: acetylene hydrogenation, Pd-Ag/Al₂O₃, artificial neural network, modeling, optimal design

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Authors: Mahmoud Khamaira, Ahmed Abu-Siada, Yasser Alharbi

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Doubly Fed Induction Generators (DFIGs) are currently extensively used in variable speed wind power plants due to their superior advantages that include reduced converter rating, low cost, reduced losses, easy implementation of power factor correction schemes, variable speed operation and four quadrants active and reactive power control capabilities. On the other hand, DFIG sensitivity to grid disturbances, especially for voltage sags represents the main disadvantage of the equipment. In this paper, a coil is proposed to be integrated within the DFIG converters to improve the overall performance of a DFIG-based wind energy conversion system (WECS). The charging and discharging of the coil are controlled by controlling the duty cycle of the switches of the dc-dc chopper. Simulation results reveal the effectiveness of the proposed topology in improving the overall performance of the WECS system under study.

Keywords: doubly fed induction generator, coil, wind energy conversion system, converter topology

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Authors: Ela Ari, Aysi̇ma Findikoglu

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Consumers’ switching GSM operators’ has been an important research issue since the rise of their competitive offers. Recent research has looked at consumer switching behavior through the theory of planned behavior, but not yet extended the theory with identity, psycho-social and cultural influences within the service context. This research explores an extended version of the theory of planned behavior including social and financial risks and brand loyalty. Moreover, the role of individualism and collectivism at the individual level is investigated in a collectivistic culture that moves toward to individualism due to changing family relationships, use of technology and education. Our preliminary analysis showed that financial risk and vertical individualism prove to be a significant determinant of intention to switch. The study also investigates social risk and intention, subjective norm, perceived behavioral control relationship. The effect of individualism and collectivism and attitudes relationship has been also examined within a service industry. Implications for marketing managers and scholars are also discussed.

Keywords: attitude, individualism, intention, subjective norm

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Authors: N. K. Chougule, G. V. Parishwad

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The pin fin heat sink is a novel heat transfer device to transfer large amount of heat through with very small temperature differences and it also possesses large uniform cooling characteristics. Pin fins are widely used as elements that provide increased cooling for electronic devices. Increasing demands regarding the performance of such devices can be observed due to the increasing heat production density of electronic components. For this reason, extensive work is being carried out to select and optimize pin fin elements for increased heat transfer. In this paper, the effects of design parameters and the optimum design parameters for a Pin-Fin heat sink (PFHS) under multi-jet impingement case with thermal performance characteristics have been investigated by using Taguchi methodology based on the L9 orthogonal arrays. Various design parameters, such as pin-fin array size, gap between nozzle exit to impingement target surface (Z/d) and air velocity are explored by numerical experiment. The average convective heat transfer coefficient is considered as the thermal performance characteristics. The analysis of variance (ANOVA) is applied to find the effect of each design parameter on the thermal performance characteristics. Then the results of confirmation test with the optimal level constitution of design parameters have obviously shown that this logic approach can effective in optimizing the PFHS with the thermal performance characteristics. The analysis of the Taguchi method reveals that, all the parameters mentioned above have equal contributions in the performance of heat sink efficiency. Experimental results are provided to validate the suitability of the proposed approach.

Keywords: Pin Fin Heat Sink (PFHS), Taguchi method, CFD, thermal performance

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Authors: Yakup Sahin, Naim Suleyman Ting, Ismail Aksoy

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In this paper, a single phase soft switched Zero Voltage Transition and Zero Current Transition (ZVT-ZCT) Power Factor Correction (PFC) boost converter is proposed. In the proposed PFC converter, the main switch turns on with ZVT and turns off with ZCT without any additional voltage or current stresses. Auxiliary switch turns on and off with zero current switching (ZCS). Also, the main diode turns on with zero voltage switching (ZVS) and turns off with ZCS. The proposed converter has features like low cost, simple control and structure. The output current and voltage are controlled by the proposed PFC converter in wide line and load range. The theoretical analysis of converter is clarified and the operating steps are given in detail. The simulation results of converter are obtained for 500 W and 100 kHz. It is observed that the semiconductor devices operate with soft switching (SS) perfectly. So, the switching power losses are minimum. Also, the proposed converter has 0.99 power factor with sinusoidal current shape.

Keywords: power factor correction, zero-voltage transition, zero-current transition, soft switching

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Authors: Justin Reverdi, Sixin Zhang, Serge Gratton, Said Aoues, Thomas Pellegrini

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In Vapor Cycle Systems, the flow sensor plays a key role in different monitoring and control purposes. However, physical sensors can be expensive, inaccurate, heavy, cumbersome, or highly sensitive to vibrations, which is especially problematic when embedded into an aircraft. The conception of a virtual sensor based on other standard sensors is a good alternative. In this paper, a data-driven model using a Convolutional Neural Network is proposed to estimate the flow of the compressor. To fit the model to our dataset, we tested different loss functions. We show in our application that a Dynamic Time Warping based loss function called DILATE leads to better dynamical performance than the vanilla mean squared error (MSE) loss function. DILATE allows choosing a trade-off between static and dynamic performance.

Keywords: deep learning, dynamic time warping, vapor cycle system, virtual sensor

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Authors: Yaru Meng

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The study contributes to the small but growing literature around computerized approaches to dynamic assessment (C-DA), wherein individual items are accompanied by mediating prompts. Mediation in the current computerized dynamic listening assessment (CDLA) was informed by an attribute-based mediation model (AMM) that identified the underlying L2 listening cognitive abilities and associated descriptors. The AMM served to focus mediation during C-DA on particular cognitive abilities with a goal of specifying areas of learner difficulty. 86 low-intermediate L2 English learners from a university in China completed three listening assessments, with an experimental group receiving the CLDA system and a control group a non-dynamic assessment. As an assessment, the use of the AMM in C-DA generated detailed diagnoses for each learner. In addition, both within- and between-group repeated ANOVA found greater gains at the level of specific attributes among C-DA learners over the course of a 5-week study. Directions for future research are discussed.

Keywords: computerized dynamic assessment, effectiveness, English as foreign language listening, attribute-based mediation model

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Authors: Yael Livneh, Shay Tzafrir, Ilan Meshoulam

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Technological startup companies have been recognized as bearing tremendous potential for business and economic success. However, many entrepreneurs who produce promising innovative ideas fail to implement them as successful businesses. A key argument for such failure is the entrepreneurs' lack of competence in adaptation of the relevant level of formality of human resource management (HRM). The purpose of the present research was to examine multiple antecedents and consequences of HRM formality in growing startup companies. A review of the research literature identified two central components of HRM formality: HR control and professionalism. The effect of three contextual predictors was examined. The first was an intra-organizational factor: the development level of the organization. We based on a differentiation between knowledge exploration and knowledge exploitation. At a given time, the organization chooses to focus on a specific mix of these orientations, a choice which requires an appropriate level of HRM formality, in order to efficiently overcome the challenges. It was hypothesized that the mix of orientations of knowledge exploration and knowledge exploitation would predict HRM formality. The second predictor was the personal characteristics the organization's leader. According the idea of blueprint effect of CEO's on HRM, it was hypothesized that the CEO's cognitive style would predict HRM formality. The third contextual predictor was an external organizational factor: the level of investor involvement. By using the agency theory, and based on Transaction Cost Economy, it was hypothesized that the level of investor involvement in general management and HRM would be positively related to the HRM formality. The effect of formality on trust was examined directly and indirectly by the mediation role of procedural justice. The research method included a time-lagged field study. In the first study, data was obtained using three questionnaires, each directed to a different source: CEO, HR position-holder and employees. 43 companies participated in this study. The second study was conducted approximately a year later. Data was recollected using three questionnaires by reapplying the same sample. 41 companies participated in the second study. The organizations samples included technological startup companies. Both studies included 884 respondents. The results indicated consistency between the two studies. HRM formality was predicted by the intra-organizational factor as well as the personal characteristics of the CEO, but not at all by the external organizational context. Specifically, the organizational orientations was the greatest contributor to both components of HRM formality. The cognitive style predicted formality to a lesser extent. The investor's involvement was found not to have any predictive effect on the HRM formality. The results indicated a positive contribution to trust in HRM, mainly via the mediation of procedural justice. This study contributed a new concept for technological startup company development by a mixture of organizational orientation. Practical implications indicated that the level of HRM formality should be matched to that of the company's development. This match should be challenged and adjusted periodically by referring to the organization orientation, relevant HR practices, and HR function characteristics. A relevant matching could enhance further trust and business success.

Keywords: control, formality, human resource management, organizational development, professionalism, technological startup company

Procedia PDF Downloads 249

Authors: Youping Huang, Yang Liu

Abstract:

Mountainous cities have unique landscape relationship, topography and urban spatial pattern different from plain cities, which put forward different requirements for greenway system planning strategy. Taking the greenway planning of Chengkou County in Chongqing as an example, this paper discusses the greenway system planning strategy of mountainous cities based on urban and rural green space, urban landscape resources, human resources and other factors. Through multi-angle maintenance of landscape pattern, multi-objective integration of urban resources, multi-level construction of greenway network, and multi-interactive development control, the sustainable development of mountain city landscape resources is realized, the new urban ecology is constructed, and the quality of life of urban and rural residents is improved.

Keywords: greenway planning, mountain city, landscape pattern, cultural resources, chongqing

Procedia PDF Downloads 80

Authors: Utkan Mutman, Cihan Dirlik

Abstract:

Kocaeli/TURKEY district in which wastewater held in a chosen field increased property has made piling in order to improve the ground under the aeration basin. In this study, the degree of improvement the ground after bored piling held in the field were investigated. In this context, improving the ground before and after the investigation was carried out and that the solution values obtained by the finite element method analysis using Plaxis program have been made. The diffuses in the aeration basin whose treatment is to aide is influenced with and without geogrid on the ground. On the ground been improved, for the purpose of control of manufactured bored piles, pile continuity, and pile load tests were made. Taking into consideration both the data in the field as well as dynamic loads in the aeration basic, an analysis was made on Plaxis program and compared the data obtained from the analysis result and data obtained in the field.

Keywords: geogrid, bored pile, soil improvement, plaxis

Procedia PDF Downloads 256

Authors: Adetoba B. Tiwalola, Adedeji W. Oyediran, Yekini N. Asafe, Akinwole A. Kikelomo

Abstract:

Mechatronics is synergistic integration of mechanical engineering, with electronics and intelligent computer control in the design and manufacturing of industrial products and processes. Automobile (auto car, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor) is a mechatronic system which served as major means of transportation around the world. Virtually all community has a need for automobile. This makes automobile issues as related to diagnostic and repair interesting to all communities. Consequent to the diversification of skill in diagnosing automobile faults and approaches in solving some problems and innovation in automobile industry. It is appropriate to say that repair and diagnostic of automobile will be better enhanced if community has opportunity of sharing knowledge and idea globally. This paper discussed the desirable elements in automobile as mechatronics system and present conceptual framework of virtual community model for knowledge sharing among automobile users.

Keywords: automobile, automobile users, knowledge sharing, mechatronics system, virtual community

Procedia PDF Downloads 431

Authors: Jitka Hroudová, Martin Sedlmajer, Jiří Zach

Abstract:

Problems insulation of building structures is often closely connected with the problem of moisture remediation. In the case of historic buildings or if only part of the redevelopment of envelope of structures, it is not possible to apply the classical external thermal insulation composite systems. This application is mostly effective thermal insulation plasters with high porosity and controlled capillary properties which assures improvement of thermal properties construction, its diffusion openness towards the external environment and suitable treatment capillary properties of preventing the penetration of liquid moisture and salts thereof toward the outer surface of the structure. With respect to the current trend of reducing the energy consumption of building structures and reduce the production of CO2 is necessary to develop capillary-active materials characterized by their low density, low thermal conductivity while maintaining good mechanical properties. The aim of researchers at the Faculty of Civil Engineering, Brno University of Technology is the development and study of hygrothermal behaviour of optimal materials for thermal insulation and rehabilitation of building structures with the possible use of alternative, less energy demanding binders in comparison with conventional, frequently used binder, which represents cement. The paper describes the evaluation of research activities aimed at the development of thermal insulation and repair materials using lightweight aggregate and alternative binders such as metakaolin and finely ground fly ash.

Keywords: thermal insulating plasters, rehabilitation materials, thermal conductivity, lightweight aggregate, alternative binders.

Procedia PDF Downloads 290