Search results for: information systems life cycle

Authors: Ahmed A. A. Radwan, Bahgat A. Abdel Latef, Abdel Mgeid A. Ali, Osman A. Sadek

Abstract:

This study investigates the use of genetic algorithms in information retrieval. The method is shown to be applicable to three well-known documents collections, where more relevant documents are presented to users in the genetic modification. In this paper we present a new fitness function for approximate information retrieval which is very fast and very flexible, than cosine similarity fitness function.

Keywords: Cosine similarity, Fitness function, Genetic Algorithm, Information Retrieval, Query learning.

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Authors: E. Farjami, La. Mohammadzadeh Afshar, Li. Mohammadzade Afshar, A. Taran

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Nowadays, flexibility introduced as a modern technology in furniture systems especially in interior planning design. According to results, the most important impact of these systems can be seen on open plan design that makes workspaces comfortable and increases the productivity of employees besides making good relationship between them. Briefly, there are some factors along with new systems in furniture design help create inappropriate space to make working better and easier while it has modular planning organization. It brings about some approaches to have a successful space for open offices with modular design and flexible furniture systems. These approaches have been investigated in open and close offices at Eastern Mediterranean University (EMU) in Famagusta, Cyprus, using information extracted from questionnaires.

Keywords: Flexibility, Flexible Furniture, Modular design, Open offices, Modular furniture systems.

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Authors: Yahia M., Laanani I., Benbia S., Hachemi M., Massinissa Y.

Abstract:

Uterine and oviducal fluids are necessary for capacitation of the spermatozoa and early embryonic development. The aim of the present study was to determine the effects of estrous cycle phases (follicular and luteal) on some biological parameters (enzymes, electrolytes and total proteins) in uterine and oviducal secretions of ewes. Oviducal and uterine fluids were collected, diluted and centrifuged. According to our results, concentrations of GPT, G6PDH, total proteins, K and Na were significantly (P <0.05) higher at the luteal phase, however, the levels of aldolase, Mg, Ca and P were significantly (P <0.05) higher at the follicular phase in uterine secretions. While, only oviducal K and Ca were significantly (P<0.05) higher at the follicular phase. Our study revealed the existence of significant cyclic variations for some uterine and oviducal parameters which indicates the effect of ovarian hormones on the components of genital secretions.

Keywords: Biochemical parameters, estrous cycle, ewe, genital secretion.

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Authors: Chih-Neng Liang, Huang-Bin Huang, Bo-Chiuan Chen

Abstract:

Nowadays, keyless entry systems are widely adopted for vehicle immobilizer systems due to both advantages of security and convenience. Keyless entry systems could overcome brute-force key guessing attack, statistics attack and masquerade attack, however, they can't prevent from thieves stealing behavior. In this paper, we proposed a new architecture try to improve the existent flaws. The integration of the keyless entry system and the fingerprint identification technology is more suitable to implement on the portable transponder to achieve higher security needs. We also adopt and modify AES security protocol for life expectancy and security of the portable transponder. In addition, the identification of a driver's fingerprint makes the service of automatic reinstatement of a driver's preferences become possible. Our design can satisfy not only the three kinds of previous illegal attacks, but also the stealing situation. Furthermore, many practical factors, such as costs, life expectancy and performance, have been well considered in the design of portable transponder.

Keywords: Keyless entry-system, fingerprint identification, AES security protocol, vehicle immobilizer system.

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Authors: Shunzuo Wu, Xudong Luo, Yuanxiu Liao

Abstract:

Recently, the rapid development of deep learning makes artificial intelligence (AI) penetrate into many fields, replacing manual work there. In particular, AI systems also become a research focus in the field of automatic office. To meet real needs in automatic officiating, in this paper we develop an automatic form filling system. Specifically, it uses two classical neural network models and several word embedding models to classify various relevant information elicited from the Internet. When training the neural network models, we use less noisy and balanced data for training. We conduct a series of experiments to test my systems and the results show that our system can achieve better classification results.

Keywords: Personal information, deep learning, auto fill, NLP, document analysis.

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Authors: Rohiza Ahmad, Rozana Kasbon, Eliza Mazmee Mazlan, Aliza Sarlan

Abstract:

Due to the mobility of users, many information systems are now developed with the capability of supporting retrieval of information from both static and mobile users. Hence, the amount, content and format of the information retrieved will need to be tailored according to the device and the user who requested for it. Thus, this paper presents a framework for the design and implementation of such a system, which is to be developed for communicating final examination related information to the academic community at one university in Malaysia. The concept of personalization will be implemented in the system so that only highly relevant information will be delivered to the users. The personalization concept used will be based on user profiling as well as context. The system in its final state will be accessible through cell phones as well as intranet connected personal computers.

Keywords: System framework, personalization, informationcommunicating system, multi-device.

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Authors: N. Mantalay, N. Chakpitak, W. Janchai, P. Sureepong

Abstract:

Work stress causes the organizational work-life imbalance of employees. Because of this imbalance, workers perform with lower effort to finish assignments and thus an organization will experience reduced productivity. In order to investigate the problem of an organizational work-life imbalance, this qualitative case study focuses on an organizational work-life imbalance among Thai software developers in a German-owned company in Chiang Mai, Thailand. In terms of knowledge management, fishbone diagram is useful analysis tool to investigate the root causes of an organizational work-life imbalance systematically in focus-group discussions. Furthermore, fishbone diagram shows the relationship between causes and effects clearly. It was found that an organizational worklife imbalance among Thai software developers is influenced by management team, work environment, and information tools used in the company over time.

Keywords: knowledge management, knowledge worker, worklife imbalance, fishbone diagram

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Authors: Dong Sang Yoo

Abstract:

We consider nonlinear uncertain systems such that a  priori information of the uncertainties is not available. For such  systems, we assume that the upper bound of the uncertainties is  represented as a Fredholm integral equation of the first kind and we  propose an adaptation law that is capable of estimating the upper  bound and design a continuous robust control which renders nonlinear  uncertain systems ultimately bounded.

 

Keywords: Adaptive Control, Estimation, Fredholm Integral, Uncertain System.

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Authors: Ye. Shapovalov, V. Shapovalov, O. Stryzhak, A. Salyuk

Abstract:

Over the past decades, amount of scientific information has been growing exponentially. It became more complicated to process and systemize this amount of data. The approach to systematization of scientific information on the production of biogas based on the ontological IT platform “T.O.D.O.S.” has been developed. It has been proposed to select semantic characteristics of each work for their further introduction into the IT platform “T.O.D.O.S.”. An ontological graph with a ranking function for previous scientific research and for a system of selection of microorganisms has been worked out. These systems provide high performance of information management of scientific information.

Keywords: Ontology-based analysis, analysis of scientific data, methanogenesys, microorganism hierarchy, T.O.D.O.S.

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Authors: Z. Gomar, H. Heidary, M. Davoudi

Abstract:

This research deals with techno economic analysis to select the most economic desalination method for Asalouyeh combined cycle power plant . Due to lack of fresh water, desalination of sea water is necessary to provide required DM water of Power Plant. The most common desalination methods are RO, MSF, MED, and MED–TVC. In this research, methods of RO, MED, and MED– TVC have been compared. Simulation results show that recovery of heat of exhaust gas of main stack is optimum case for providing DM water required for injected steam of MED desalination. This subject is very important because of improving thermal efficiency of power plant using extra heat recovery. Also, it has been shown that by adding 3 rows of finned tube to de-aerator evaporator, which is very simple and low cost, required steam for generating 5200 m3/day of desalinated water is obtainable.

Keywords: Desalination, MED, thermodynamic simulation, combined cycle power plant.

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Authors: Mazziotti Gomez de Teran C., Fiore D., Cola B., Fardelli A.

Abstract:

The present paper summarizes the analysis of the request for consultation of information and data on industrial emissions made publicly available on the web site of the Ministry of Environment, Land and Sea on integrated pollution prevention and control from large industrial installations, the so called “AIA Portal”. As a matter of fact, a huge amount of information on national industrial plants is already available on internet, although it is usually proposed as textual documentation or images. Thus, it is not possible to access all the relevant information through interoperability systems and also to retrieval relevant information for decision making purposes as well as rising of awareness on environmental issue. Moreover, since in Italy the number of institutional and private subjects involved in the management of the public information on industrial emissions is substantial, the access to the information is provided on internet web sites according to different criteria; thus, at present it is not structurally homogeneous and comparable. To overcome the mentioned difficulties in the case of the Coordinating Committee for the implementation of the Agreement for the industrial area in Taranto and Statte, operating before the IPPC permit granting procedures of the relevant installation located in the area, a big effort was devoted to elaborate and to validate data and information on characterization of soil, ground water aquifer and coastal sea at disposal of different subjects to derive a global perspective for decision making purposes. Thus, the present paper also focuses on main outcomes matured during such experience.

Keywords: Public information, emissions into atmosphere, IPPC permits, territorial information systems.

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Authors: Carsten Röcker

Abstract:

This paper illustrates why existing technology acceptance models are only of limited use for predicting and explaining the adoption of future information and communication technologies. It starts with a general overview over technology adoption processes, and presents several theories for the acceptance as well as adoption of traditional information technologies. This is followed by an overview over the recent developments in the area of information and communication technologies. Based on the arguments elaborated in these sections, it is shown why the factors used to predict adoption in existing systems, will not be sufficient for explaining the adoption of future information and communication technologies.

Keywords: Technology Diffusion, Technology AcceptanceModels, Ambient Intelligence, Ubiquitous and Pervasive Computing.

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Authors: Mohammed Salahat, Steve Wade

Abstract:

This paper presents and compares the SSDDD “Systematic Soft Domain Driven Design Framework” to DDD “Domain Driven Design Framework” as a soft system approach of information systems development. The framework use SSM as a guiding methodology within which we have embedded a sequence of design tasks based on the UML leading to the implementation of a software system using the Naked Objects framework. This framework has been used in action research projects that have involved the investigation and modelling of business processes using object-oriented domain models and the implementation of software systems based on those domain models. Within this framework, Soft Systems Methodology (SSM) is used as a guiding methodology to explore the problem situation and to develop the domain model using UML for the given business domain. The framework is proposed and evaluated in our previous works, a comparison between SSDDD and DDD is presented in this paper, to show how SSDDD improved DDD as an approach to modelling and implementing business domain perspectives for Information Systems Development. The comparison process, the results, and the improvements are presented in the following sections of this paper.

Keywords: SSM, UML, domain-driven design, soft domain-driven design, naked objects, soft language, information retrieval, multimethodology.

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Authors: Musthafah b. Mohd.Tahir, Noboru Yamada, Tetsuya Hoshino

Abstract:

This paper describes the experimental efficiency of a compact organic Rankine cycle (ORC) system with a compact rotary-vane-type expander. The compact ORC system can be used for power generation from low-temperature heat sources such as waste heat from various small-scale heat engines, fuel cells, electric devices, and solar thermal energy. The purpose of this study is to develop an ORC system with a low power output of less than 1 kW with a hot temperature source ranging from 60°C to 100°C and a cold temperature source ranging from 10°C to 30°C. The power output of the system is rather less due to limited heat efficiency. Therefore, the system should have an economically optimal efficiency. In order to realize such a system, an efficient and low-cost expander is indispensable. An experimental ORC system was developed using the rotary-vane-type expander which is one of possible candidates of the expander. The experimental results revealed the expander performance for various rotation speeds, expander efficiencies, and thermal efficiencies. Approximately 30 W of expander power output with 48% expander efficiency and 4% thermal efficiency with a temperature difference between the hot and cold sources of 80°C was achieved.

Keywords: Organic Rankine cycle, Thermodynamic cycle, Thermal efficiency, Turbine efficiency, Waste heat recovery, Powergeneration, Low temperature heat engine.

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Authors: Irina Pyrlina

Abstract:

Author presents the results of a study conducted to identify criteria of efficient information system (IS) with serviceoriented architecture (SOA) realization and proposes a ranking method to evaluate SOA information systems using a set of architecture quality criteria before the systems are implemented. The method is used to compare 7 SOA projects and ranking result for SOA efficiency of the projects is provided. The choice of SOA realization project depends on following criteria categories: IS internal work and organization, SOA policies, guidelines and change management, processes and business services readiness, risk management and mitigation. The last criteria category was analyzed on the basis of projects statistics.

Keywords: multiple criteria threshold algorithm, serviceoriented architecture, SOA operational risks, efficiency criteria for IS architecture, projects ranking.

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Authors: Shang-Ping Lin, Shi-Hwa Lo, Ho-Li Yang

Abstract:

Company mergers and acquisitions reached their peak in the twenty-first century. Mergers and acquisitions have become one of the competitive strategies for external growth. In general, it is believed that mergers and acquisitions can create synergies. However, they require complete information technology system and service integration, especially in the banking industry. Much of the research has focused on performance evaluation, shareholder equity allocation, or even the increase of company market value after the merger and acquisition, whereas few scholars have focused on information system integration post merger and acquisition. This study indicates the role of information systems after a merger and acquisition, explaining the benefits of information system integration using a merger and acquisition case in the banking industry as an example. In addition, we discuss factors that affect the performance of information system integration, and utilize system dynamics to interpret the relationship among factors that affect information system integration performance in the banking industry after a merger and acquisition.

Keywords: Merger and Acquisition, Information SystemIntegration, System Dynamics

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Authors: Alireza Azimi Sani , Shahram Chaharmahalie

Abstract:

Internal controls of accounting are an essential business function for a growth-oriented organization, and include the elements of risk assessment, information communications and even employees' roles and responsibilities. Internal controls of accounting systems are designed to protect a company from fraud, abuse and inaccurate data recording and help organizations keep track of essential financial activities. Internal controls of accounting provide a streamlined solution for organizing all accounting procedures and ensuring that the accounting cycle is completed consistently and successfully. Implementing a formal Accounting Procedures Manual for the organization allows the financial department to facilitate several processes and maintain rigorous standards. Internal controls also allow organizations to keep detailed records, manage and organize important financial transactions and set a high standard for the organization's financial management structure and protocols. A well-implemented system also reduces the risk of accounting errors and abuse. A well-implemented controls system allows a company's financial managers to regulate and streamline all functions of the accounting department. Internal controls of accounting can be set up for every area to track deposits, monitor check handling, keep track of creditor accounts, and even assess budgets and financial statements on an ongoing basis. Setting up an effective accounting system to monitor accounting reports, analyze records and protect sensitive financial information also can help a company set clear goals and make accurate projections. Creating efficient accounting processes allows an organization to set specific policies and protocols on accounting procedures, and reach its financial objectives on a regular basis. Internal accounting controls can help keep track of such areas as cash-receipt recording, payroll management, appropriate recording of grants and gifts, cash disbursements by authorized personnel, and the recording of assets. These systems also can take into account any government regulations and requirements for financial reporting.

Keywords: Internal controls, risk assessment, financial management.

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Authors: Emilia Nercissians

Abstract:

The paper attempts to contribute to the largely neglected social and anthropological discussion of technology development on the one hand, and to redirecting the emphasis in anthropology from primitive and exotic societies to problems of high relevance in contemporary era and how technology is used in everyday life. It draws upon multidimensional models of intelligence and ideal type formation. It is argued that the predominance of computational and cognitive cosmovisions have led to technology alienation. Injection of communicative competence in artificially intelligent systems and identity technologies in the coming information society are analyzed

Keywords: convergence, nomadic computing, solidarity, status.

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Authors: J. Menčík, B. Culek, Jr., L. Beran, J. Mareš

Abstract:

Large metal and concrete structures suffer by various kinds of deterioration, and accurate prediction of the remaining life is important. This paper informs about two methods for its assessment. One method, suitable for steel bridges and other constructions exposed to fatigue, monitors the loads and damage accumulation using information systems for the operation and the finite element model of the construction. In addition to the operation load, the dead weight of the construction and thermal stresses can be included into the model. The second method is suitable for concrete bridges and other structures, which suffer by carbonatation and other degradation processes, driven by diffusion. The diffusion constant, important for the prediction of future development, can be determined from the depth-profile of pH, obtained by pH measurement at various depths. Comparison with measurements on real objects illustrates the suitability of both methods.

Keywords: Bridges, carbonatation, concrete, diagnostics, fatigue, life prediction, monitoring, railway, simulation, structures.

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Authors: Skander Jribi, Anutosh Chakraborty, Ibrahim I. El-Sharkawy, Bidyut Baran Saha, Shigeru Koyama

Abstract:

Heat powered solid sorption is a feasible alternative to electrical vapor compression refrigeration systems. In this paper, activated carbon (powder type Maxsorb and fiber type ACF-A10)- CO2 based adsorption cooling cycles are studied using the pressuretemperature- concentration (P-T-W) diagram. The specific cooling effect (SCE) and the coefficient of performance (COP) of these two cooling systems are simulated for the driving heat source temperatures ranging from 30 ºC to 90 ºC in terms of different cooling load temperatures with a cooling source temperature of 25 ºC. It is found from the present analysis that Maxsorb-CO2 couple shows higher cooling capacity and COP. The maximum COPs of Maxsorb-CO2 and ACF(A10)-CO2 based cooling systems are found to be 0.15 and 0.083, respectively. The main innovative feature of this cooling cycle is the ability to utilize low temperature waste heat or solar energy using CO2 as the refrigerant, which is one of the best alternative for applications where flammability and toxicity are not allowed.

Keywords: Activated carbon, Adsorption cooling system, Carbon dioxide, Performance evaluation.

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Authors: Reza Ghaemi, Amin Milani Fard, Hamid Tabatabaee, Mahdi Sadeghizadeh

Abstract:

Due to new distributed database applications such as huge deductive database systems, the search complexity is constantly increasing and we need better algorithms to speedup traditional relational database queries. An optimal dynamic programming method for such high dimensional queries has the big disadvantage of its exponential order and thus we are interested in semi-optimal but faster approaches. In this work we present a multi-agent based mechanism to meet this demand and also compare the result with some commonly used query optimization algorithms.

Keywords: Information retrieval systems, list fusion methods, document score, multi-agent systems.

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Authors: Mohamad Mahdavi, Mojtaba Mahdavi

Abstract:

This paper tries to represent a new method for computing the reliability of a system which is arranged in series or parallel model. In this method we estimate life distribution function of whole structure using the asymptotic Extreme Value (EV) distribution of Type I, or Gumbel theory. We use EV distribution in minimal mode, for estimate the life distribution function of series structure and maximal mode for parallel system. All parameters also are estimated by Moments method. Reliability function and failure (hazard) rate and p-th percentile point of each function are determined. Other important indexes such as Mean Time to Failure (MTTF), Mean Time to repair (MTTR), for non-repairable and renewal systems in both of series and parallel structure will be computed.

Keywords: Reliability, extreme value, parallel, series, lifedistribution

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Authors: B. T. Sayed, Nafaâ Jabeur, M. Aref

Abstract:

Creation and maintenance of knowledge management systems has been recognized as an important research area. Consecutively lack of accurate results from knowledge management systems limits the organization to apply their knowledge management processes. This leads to a failure in getting the right information to the right people at the right time thus followed by a deficiency in decision making processes. An Intranet offers a powerful tool for communication and collaboration, presenting data and information, and the means that creates and shares knowledge, all in one easily accessible place. This paper proposes an archetype describing how a knowledge management system, with the support of intranet capabilities, could very much increase the accuracy of capturing, storing and retrieving knowledge based processes thereby increasing the efficiency of the system. This system will expect a critical mass of usage, by the users, for intranet to function as knowledge management systems. This prototype would lead to a design of an application that would impose creation and maintenance of an effective knowledge management system through intranet. The aim of this paper is to introduce an effective system to handle capture, store and distribute knowledge management in a form that may not lead to any failure which exists in most of the systems. The methodology used in the system would require all the employees, in the organization, to contribute the maximum to deliver the system to a successful arena. The system is still in its initial mode and thereby the authors are under the process to practically implement the ideas, as mentioned in the system, to produce satisfactory results.

Keywords: Knowledge Management Systems, Intranet, Methodology.

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Authors: Huda Algharib, Amal Algharib, Hanan Algharib, Ali Mohammad Alqudah

Abstract:

Image registration is an important topic for many imaging systems and computer vision applications. The standard image registration techniques such as Mutual information/ Normalized mutual information -based methods have a limited performance because they do not consider the spatial information or the relationships between the neighbouring pixels or voxels. In addition, the amount of image noise may significantly affect the registration accuracy. Therefore, this paper proposes an efficient method that explicitly considers the relationships between the adjacent pixels, where the gradient information of the reference and scene images is extracted first, and then the cosine similarity of the extracted gradient information is computed and used to improve the accuracy of the standard normalized mutual information measure. Our experimental results on different data types (i.e. CT, MRI and thermal images) show that the proposed method outperforms a number of image registration techniques in terms of the accuracy.

Keywords: Image registration, mutual information, image gradients, Image transformations.

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Authors: Munehiro Iwami

Abstract:

A property is persistent if for any many-sorted term rewriting system , has the property if and only if term rewriting system , which results from by omitting its sort information, has the property. Zantema showed that termination is persistent for term rewriting systems without collapsing or duplicating rules. In this paper, we show that the Zantema's result can be extended to term rewriting systems on ordered sorts, i.e., termination is persistent for term rewriting systems on ordered sorts without collapsing, decreasing or duplicating rules. Furthermore we give the example as application of this result. Also we obtain that completeness is persistent for this class of term rewriting systems.

Keywords: Theory of computing, Model-based reasoning, term rewriting system, termination

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Authors: Hakim T. Kadhim, Faris A. Jabbar, Aldo Rona, Audrius Bagdanaviciu

Abstract:

Computer-based optimization techniques can be employed to improve the efficiency of energy conversions processes, including reducing the aerodynamic loss in a thermal power plant turbomachine. In this paper, towards mitigating secondary flow losses, a design optimization workflow is implemented for the casing geometry of a 1.5 stage axial flow turbine that improves the turbine isentropic efficiency. The improved turbine is used in an open thermodynamic gas cycle with regeneration and cogeneration. Performance estimates are obtained by the commercial software Cycle – Tempo. Design and off design conditions are considered as well as variations in inlet air temperature. Reductions in both the natural gas specific fuel consumption and in CO₂ emissions are predicted by using the gas turbine cycle fitted with the new casing design. These gains are attractive towards enhancing the competitiveness and reducing the environmental impact of thermal power plant.

Keywords: Axial flow turbine, computational fluid dynamics, gas turbine power plant, optimization.

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Authors: Faezeh Mosallat, Eric L. Bibeau, Tarek El Mekkawy

Abstract:

Parabolic solar trough systems have seen limited deployments in cold northern climates as they are more suitable for electricity production in southern latitudes. A numerical dynamic model is developed to simulate troughs installed in cold climates and validated using a parabolic solar trough facility in Winnipeg. The model is developed in Simulink and will be utilized to simulate a trigeneration system for heating, cooling and electricity generation in remote northern communities. The main objective of this simulation is to obtain operational data of solar troughs in cold climates and use the model to determine ways to improve the economics and address cold weather issues. In this paper the validated Simulink model is applied to simulate a solar assisted absorption cooling system along with electricity generation using Organic Rankine Cycle (ORC) and thermal storage. A control strategy is employed to distribute the heated oil from solar collectors among the above three systems considering the temperature requirements. This modelling provides dynamic performance results using measured meteorological data recorded every minute at the solar facility location. The purpose of this modeling approach is to accurately predict system performance at each time step considering the solar radiation fluctuations due to passing clouds. Optimization of the controller in cold temperatures is another goal of the simulation to for example minimize heat losses in winter when energy demand is high and solar resources are low. The solar absorption cooling is modeled to use the generated heat from the solar trough system and provide cooling in summer for a greenhouse which is located next to the solar field. The results of the simulation are presented for a summer day in Winnipeg which includes comparison of performance parameters of the absorption cooling and ORC systems at different heat transfer fluid (HTF) temperatures.

Keywords: Absorption cooling, parabolic solar trough, remote community, organic Rankine cycle.

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Authors: Peter G. Youssef, Saad M. Mahmoud, Raya K. Al-Dadah

Abstract:

Many water desalination technologies have been developed but in general they are energy intensive and have high cost and adverse environmental impact. Recently, adsorption technology for water desalination has been investigated showing the potential of using low temperature waste heat (50-85oC) thus reducing energy consumption and CO2 emissions. This work mathematically compares the performance of an adsorption cycle that produces two useful effects namely, fresh water and cooling using two different adsorbents, silica-gel and an advanced zeolite material AQSOA-ZO2, produced by Mitsubishi plastics. It was found that at low chilled water temperatures, typically below 20oC, the AQSOA-Z02 is more efficient than silica-gel as the cycle can produce 5.8 m3 of fresh water per day and 50.1 Rton of cooling per tonne of AQSOA-ZO2. Above 20oC silica-gel is still better as the cycle production reaches 8.4 m3 per day and 62.4 Rton per tonne of silica-gel. These results show the potential of using the AQSOA-Z02 at low chilled water temperature for water desalination and cooling applications.

Keywords: Adsorption, desalination, refrigeration, seawater.

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Authors: S. Bennoud, S. Hocine, H. Slme

Abstract:

Developments in turbine cooling technology play an important role in increasing the thermal efficiency and the power output of recent gas turbines, in particular the turbojets.

Advanced turbojets operate at high temperatures to improve thermal efficiency and power output. These temperatures are far above the permissible metal temperatures. Therefore, there is a critical need to cool the blades in order to give theirs a maximum life period for safe operation.

The focused objective of this work is to calculate the turbojet performances, as well as the calculation of turbine blades cooling.

The developed application able the calculation of turbojet performances to different altitudes in order to find a point of optimal use making possible to maintain the turbine blades at an acceptable maximum temperature and to limit the local variations in temperatures in order to guarantee their integrity during all the lifespan of the engine.

Keywords: Brayton cycle, Turbine Blades Cooling, Turbojet Cycle, turbojet performances.

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Authors: D. I. De Souza, G. P. Azevedo, R. Rocha

Abstract:

In this paper we will develop a sequential life test approach applied to a modified low alloy-high strength steel part used in highway overpasses in Brazil.We will consider two possible underlying sampling distributions: the Normal and theInverse Weibull models. The minimum life will be considered equal to zero. We will use the two underlying models to analyze a fatigue life test situation, comparing the results obtained from both.Since a major chemical component of this low alloy-high strength steel part has been changed, there is little information available about the possible values that the parameters of the corresponding Normal and Inverse Weibull underlying sampling distributions could have. To estimate the shape and the scale parameters of these two sampling models we will use a maximum likelihood approach for censored failure data. We will also develop a truncation mechanism for the Inverse Weibull and Normal models. We will provide rules to truncate a sequential life testing situation making one of the two possible decisions at the moment of truncation; that is, accept or reject the null hypothesis H0. An example will develop the proposed truncated sequential life testing approach for the Inverse Weibull and Normal models.

Keywords: Sequential life testing, normal and inverse Weibull models, maximum likelihood approach, truncation mechanism.

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