Modeling in Engineering
Year:2018 | Volume:16 | Issue:54|Papers Count:32

In this paper with regard to the weaknesses in the various phases of the agent oriented methodologies and impact that these shortcomings can be in the quality and efficiency of software projects, a combinatory solution named (AP) from the ADELFE and PASSI methodologies have proposed. Therefore, in order to examine the two methodologies in the form of a comprehensive evaluation framework based on the criteria the concepts and perception, language modeling, process and pragmatism have been evaluated. Due to the limitations of time and resources, the decision to choose the sample methodologies for the evaluation and unification was adopted. This selection is based on the application of the methodology and their combination ability from expert's point of view. Based on the results of the assessment, methodology-oriented operating systems analysis steps ADELFE is well supported and its design stages because of lack of ability to model, is not complete. According to the evaluation results, the ADELFE methodology well supports stages of agent-oriented systems' analysis but its design stages because of lack of agent capability modeling is not complete. On the other hand, since PASSI methodologies well support the design stages and interactions between agents, a combined methodology based on analysis stage of ADELFE methodology and design stage of PASSI methodologies is proposed. In order to describe the various phases of this methodology, it has been used in a case study. The results of this research can be Provide background for introduction of the next generation of agent-oriented methodologies.

Data warehouses are centralized repositories collected from various heterogeneous sources in a wide range of time (time-variant) for decision support systems. Data warehouses are data sources used in decision making processes by online analytical processing. The process of developing a data warehouse is done through operational database analyzing, analytical requirement identification and finally designing in conceptual, logical and physical levels. In this paper, the design models at different levels of data warehouses are researched and the logical level models are compared and analyzed with respect to their properties. Finally, an improved model is proposed in logical level that combines two models (star and snowflake) in the form of a two-layered model. Queries response time measure is used to compare the proposed model with existing models. Experiments show that the proposed model improves the response time of queries. In fact, the response time of queries on the proposed model (two-layer) is improved 58. 53 percent in average versus star model, and 96. 61 percent in average versus snowflake model.

Nowadays the effort estimation of software development is crucial in Software projects management. Not only have the accurate estimate of cost help customers and investors, but also it will be effective in rational decision-making in the implementation and management of software projects. Various estimation models have been invented and used so far. Many of the current effort estimation approaches are adopted by collecting data from previous projects. Case-based reasoning (CBR) is one of the successful techniques of effort estimation in software projects. This method alone is not very accurate, a defect which can be corrected by creating hybrid models. In this paper, CBR was combined with two separate metaheuristic algorithms including particle swarm optimization (PSO) and the firefly algorithm to propose a new hybrid model. Then the performance of the proposed model was evaluated. According to the results of the proposed model on Cocomo, Albrecht and Maxwell datasets, the firefly algorithm showed an acceptable performance.

In this paper, the impact of electric vehicles (EVs) and a price-based and an incentive-based demand response programs and the combination of both programs, has been investigated on the optimal operation of the distribution system, which owns a wind unit, in the framework of a new bi-level model. In this model, simultaneously, uncertainty of wind unit and electric vehicles are also considered. The aim of both levels is to maximization the profits. In the upper-level, the distribution system, due to the existence of a wind unit and the vehicle to grid capability of EVs, gains more profit by not purchasing the electrical energy from the upstream network. At the lower-level, owner of the EVs parking lots is obtained more benefit, due to the selling of energy to EVs owners and distribution system. Forasmuch as this model is converted to single-level mix-integer linear problem by using of Karush– Kuhn– Tucker (KKT) conditions and auxiliary binary variables and is solved by GAMS software. The presented model is tested on the IEEE 15-bus distribution system over a 24-h period and results prove the effectiveness of the model.

The main portion of the power consumption in high speed register files is related to read out paths which are implemented using the dynamic circuits. For this reason, a new dynamic circuit technique is proposed in this paper to reduce the power consumption of the register files without significant speed and noise immunity degradation. In the proposed dynamic circuit, the pull down network is partitioned to the some smaller pull down networks to increase the circuit performance. Moreover, pull-down networks are precharged using NMOS transistors to reduce the voltage swing and hence decrease the power consumption. A 64-word x 32-bit 2-read, 1-write ported register file is implemented using the proposed circuit technique. Simulation of register files are performed using HSPICE simulator in low-Vth 90-nm CMOS technology model. Simulation results demonstrate 37% and 36% reduction in power and delay respectively at the same noise immunity compared to the conventional register file.

Rapid population growth and urbanization in recent decades causes the principal problems in human daily life. One of the main goals of research in the field of traffic is to optimize the flow of urban transport. In this study, using Petri nets modelling and prioritizing the urban public transport system to other cars, the traffic lights on a crossroads are adjusted so that as much as possible, a bus crosses the crossroads. As a result, the waiting time for the bus passengers is reduced and due to the high capacity of a bus, the total travel time for the passengers passing through the intersection is shortened. So that the stopping time for the passenger is reduced by at least 8 percent in average at best situation. This amount varies in different bus traffic conditions. Another advantages of this method is encouraging people to use the urban public transportation systems and this reduce the transport flow.

In this research, the support vector machine model was used to predict the Taleh Zang stream flow base on the data from 10 hydrometric and 8 rainfall stations upstream of the watershed in 20 years (1992-2011). To this aim and in the first step, influence of applying flow rate time series, rainfall, and a combination of these two parameters as an input; and in the next step, influence of number of upstream hydrometric and rainfall stations on forecast results were examined. The results were compared by using three statistical indicators: correlation coefficient (R2), Root-Mean-Square Error (RMSE), and standard Error (SE). The results showed that, using rainfall statistics along with the stream flow as an input to the model with R2of 0. 884, RMSE of 38. 41, and SE of 0. 28 in comparison to the stream flow statistics as an input to the model with R2 of 0. 871, RMSE of 40. 20, and SE of 0. 29 will improve accuracy of the forecast. Whereas, only application of rainfall time series with correlation coefficient of 0. 225, RMSE of 157. 73 and SE of 0. 62 greatly increases error values in the results. Moreover, through increase of number of upstream hydrometric and rainfall stations, the model would be capable of forecasting stream flow with more accuracy.

Service-oriented architecture is one of the fields of software engineering that enables a connection between the two systems in a heterogeneous network with different technology. Architectural features include the ability to reuse and agility against future changes. In the service-oriented architecture, one of the most important and fundamental challenge is that despite various code generators that introduced in this field, there are still shortcomings in the various phases of the code generator. In this paper, due to the weaknesses of the code generators in the different phases and that these shortcomings be found in the quality, and production software systems, have to offer a hybrid approach for the introduction of two references to the code generator. In order to use the advantages of the above two code generator, a hybrid code generator (SOG) is offered. Also, in order to increase the efficiency in the production of software systems using the provided code generator, the new features to enhance the security the code generator, increase programming languages supported, multiple formats for the transmission of information between client and server, adding a cryptographic layer and the production of panels for database management is provided on the web. The main objective of this paper is the code generator provides the codes related to service-oriented architecture. In order to assess the ability of the proposed code generator, the code generator is evaluated based on criteria related to different protocols and data transfer between client and server.

This research investigates the efficiency of the self-centering steel braced frame equipped with replaceable yielding fuses and post-tensioning cables subjected to far-field records and near-field pulse-like ground motions. For this purpose, engineering seismic demand parameters for tewelve self-centering steel braced frames under far-field ground motions are compared with those for near-field ground motions. The braced frames are different from seismic frame type, seismic site location, and the number of stories. The self-centering braced frames are designed using a limit-state design procedure and are simulated in OpenSees software. Nonlinear dynamic time-history analyses are conducted under design earthquake, DBE, level and maximum considerable earthquake, MCE, level. Findings demonstrate that the self-centering steel braced frames are capable of mitigating seismic damage under both near-field pulse-like and far-field ground motions, which are provided by features such as rocking behavior, re-centering action, and directing damage ability.

Many of engineering problems have nonlinear or highly nonlinear limit state functions. Different approaches have been developed in calculating of failure probability in these problems. These methods calculate failure probability by generating random samples with a specific distribution. The Monte Carlo is one the most efficient and applicable method among these approaches. However, this method has some problems including need to calculating of variable distribution function parameters and inverse cumulative density function of variables. In order to solve these deficiencies, in the present research, an efficient method for generating samples is presented. Additionally, enhancing performance of Monte Carlo method and more accurate results by minimum computational cost for functions with very low failure probability can be regarded as other advantages of the proposed method. For evaluating performance of the proposed method, four engineering problems have been investigated and the obtained results for calculating of failure probability have been compared with available methods. By applying the proposed method, such main steps can be neglected and stable results with high accuracy can be gained in comparison with traditional methods in lower sample numbers too.

Bond behavior between reinforcement and concrete, due to increasing application of reinforced concrete, is one of the most important issues all over the world. In this research, which has been done experimentally and finite element (FE) modeling (using ABAQUS software), 36 mixtures are deigned considering three cement strength grades and various percentages of polymer fibers, silica fume and nano-silica. The effects of these admixtures on the bond behavior between concrete and reinforcement and also the compressive strength of concrete are investigated. The method of applying nonlinear spring (translator) for finite element modeling is presented and the model is analyzed using nonlinear dynamic analysis. The results yielded acceptable correlation between experimental and FE model. Since there are some translators in model, it can be mentioned that the results of bond slip are not influenced by meshing algorithm. Moreover, comparison of the experimental and FE results showed that while the effect of fiber in bond strength is negligible, it can be so effective in determining the failure shape. The combination of silica fume and nano silica can also improve the bond strength about 20% so that applying equal amount of these two admixtures may leads to the best strength results.

Structural dynamic analyses need different earthquake parameters such as design base acceleration, design spectra and earthquake records. In order to obtain base acceleration and design spectra of a site, prevailing method is based on seismic hazard analyses. In this method, base acceleration and design spectra are obtained from seismicity of the region, site condition based on probable statistical methods. One of the obligations in this method is having attenuation relations for different parameter such as PGA. In this research we update and make improvements of the PGA attenuation relationship, presented by Ghodrati et al. (2007) for site rock and soil bed conditions of the seismo-active states of Zagroz and, Alborz and central Iran. A total of 858 strong-motion accelerograms recorded for Alborz and central Iran and Zagros are used to obtain attenuation relation, which 477 records due to Alborz and central Iran. Regression analysis has been done for maximum of horizontal components and PGA attenuation relation coefficients are obtained.

Today, precast concrete lining (segmental) are used as system maintenance in the majority of tunnels excavated by TBM. On the other hand, the mechanism of the joint between two segments is not known under seismic loads. In this paper a numerical study about the effect of the earthquake on the segmental supporting system and the resultant vertical and shear forces on the contact surface between two segments is investigated. The Tehran-Karaj water conveyance tunnel (Amirkabir) was used as a case study. In this study, the UDEC software was used. At the first step, the segmental lining were simulated under no slip and full slip conditions and the normal and shear forces were studied. Finally, the effect of joint stiffness between two segments were investigated. Results showed that with increasing the interface properties, the normal and shear forces in the segmental joints increased. Also with increasing the joints stiffness, the normal and shear forces on the joints increased and the normal and shear displacement decreased. In other words, the rigidity increament of supporting system is associated with flexibility decrement of lining with respect to rock medium. So, the stresses increased and displacement decreased.

In recent years, evaluation of reliability analysis of structures has become a straightforward and interesting topic among structural researchers. In the field of civil engineering, estimation of structural failure probability is highly investigated, considering probabilistic uncertainties of resistance and load parameters during modeling and designing of structures. To obtain an accurate failure probability, researchers often perform Monte Carlo simulation (MCS) that requires numerous modeling and cost. In the present study, based on MCS, an enhanced technique is developed that efficiently reduces number of structural modeling. The approach works by employing the concept of First Order Reliability Methods (FORMs) to determine closest point to the mean of random variables in failure region. Afterward, by presenting sub-intervals in various layers, to group generated samples in MCS, the possibility of reducing number of structural modeling with well-disciplined error and acceptable accuracy is achieved. In order to investigate the efficiency and robustness of the method, various numerical and engineering examples with complex limit state functions were attempted and the obtained results were compared with those based on the conventional reliability methods in the literature. Results show the high accuracy of proposed approach while the number of requires structural modeling were substantially reduced.

This paper presents a novel approach to detect and estimate cracks in Timoshenko Beams using frequencies and frequency response functions and extreme learning machine. For this purpose, the extreme learning machine used the three first natural frequencies and frequency response functions of beam structure as input which may be noisy or noise free and crack states in beam as output. This data is acquired by the analysis of cracked beams applying the finite element method. To demonstrate the potential of the proposed vibration analysis over existing ones, a validation study has been done. The performance of the presented method has been verified through two numerical examples, namely, a cantilever beam and simply supported beam containing single or multi cracks. Results indicate that the proposed method works well in prediction and estimation of crack and obtained results are accurate. Also, the results show that the presented method is sensitive to the location and severity of crack in spite of the noisy modal data.

Uncertainty is the inseparable part of the engineering analysis. These uncertainties have different Distributions. Sobol decomposition method is one of the most well-known methods of sensitivity analysis. Sobol decomposition as a robust sensitivity analysis method can only be used for uniform distribution. In the present paper, we generalize Sobol sensitivity method for all continuous and discrete distributions. Hence it can be used for wide Varity models in engineering and science of different distributions. The capability of the generalized method for precise numerical values presentation, the results of the sensitivity analysis of the Tehran seismic hazard is given. Due to the variability of materials and earthquakes, Structural and geosciences are full of uncertainties. Calculating the role of the uncertainty of each parameter in the overall uncertainty can be to optimize the efforts and costs necessary for outputs precision, so, it is possible to provide a precise values of sensitivities. The results are satisfactory.

Sustainable growth of a company share value, regardless of financial flow and integration of financial decisions with other physical decisions, is not reachable. Value based supply chain management, attempts to make it possible through taking working capital and fixed assets into consideration as well as factors such as sales and costs. In this paper a mixed integer programming is presented to integrate financial and physical decisions in a multi echelon, multi period and multi commodity supply chain in order to maximize economic value added, as a most prevalent value metric. Working capital management with the option of pre-buy or pre-sell as well as the credit buy or credit sell is one of the most important contributions of this paper. Performance and validation of proposed model, are proven through solving large scale problem sizes. Then, the effect of different buy and sell options, are illustrated. Company value is 64% reduced when options were not considered.

Nowadays, because of extreme competition between organizations and companies, the profit of selling products has become a challenging issue. Thus in this research we examine this issue and study the profit of organizations by designing quantity discount contract. In this paper we consider a two-level single item supply chain including a manufacturer and a retailer. The demand function depends on quality level and selling price and two conditions are studied. In the first one, decentralized condition is mentioned, for which a mathematical model is presented. In the second condition, a mathematical model for designing quantity discount contract between the members is developed and in this part the given relations are described. The main aim of this research is to assist the organizations and companies to increase their revenues, by designing the quantity discount contract. At the end a numerical example is provided to explain this research more explicit and then sensitivity analysis is performed. When all calculations are done, we discuss about results and moreover we show that how quantity discount contract can increase the profit chain rather than when this policy is not used which this issue can be noteworthy and operational for the managers of the organizations.

Revenue Management (RM) is a subfield of Operations Research that aims at maximizing revenues acquired by selling products/services in a specified period to the right customers. In this paper we address the problem of optimal assignment of general surgery ward of operation room to different classes of surgeries, each of which requiring different surgery time, using revenue management mechanisms. Deciding about accepting or rejecting a surgery request is made beside the option of preserving capacity of the operation room for future valuable requests based on the adjusted revenue (via inclusion of importance levels derived from expert opinions by an AHP approach). Data in this study were collected from Sayad-e-Shirazi Hospital of GorGan city. For formulating the problem we develop contingency and deterministic dynamic programming algorithms. Besides, we also propose a heuristic method based on a deterministic linear programming approach. The number of accepted requests for classes with higher financial priority using RM approach are compared with FCFS policy and results signify that a higher level of efficiency is attainable using the proposed RM approaches. The efficiency along with using different surgical importance levels in accepting requests is also investigated.

Availability of equipment is really important in many industries. In this paper, optimization method according to different levels of and using the Markov modeling method is proposed. The system is designed as a planned mixed-integer nonlinear components selection for choosing the systems components, which the systems costs including the cost of buying parts and cost of reduction in system capacity as well as the cost of the systems complete stop with regards the minimum level of reliability is minimized. For the application of this model, several assumptions such as simultaneous consideration of costs, reliability levels and different repair rate for different options to supply the components, have been considered that distinguishes this study from previous studies. Saving of batch ordering of components in total cost of the system is included in this study. The utilized model for a sample with four used pieces via complete counting (using the Excel software) is solved. The results of solving the model demonstrates that optimization of costs associated with increasing levels of system reliability should be with the optimization of its reliability, appropriately, to minimize the total cost of product cycle.

This research addresses a simultaneous jobs scheduling and worker assignment problem in flow shop environment in which there are some workers with different skills who can operate the jobs with different speed. The primary aim of the research is to schedule the jobs and assign the worker so that maximum completion time (Cmax) is minimized. To tackle this problem, a mixed integer linear programming model is introduced and is coded in CPLEX software so that it can obtain the optimal solutions in reasonable time. Due to NP-hardness of the research problem, CPLEX cannot achieve the optimal solutions for large-scale problems. Thus, two metaheuristic approaches based on particle swarm optimization (PSO) is proposed here. In order to trapping the PSO algorithm in local optima with high probability, the performance of the PSO algorithm is improved by simulated annealing (SA) algorithm (IPSO). The experimental results show that the IPSO algorithm can generate better results in entire scales and the superiority of the IPSO is significant in the large scale.

In this research, photocatalytic degradation method for COD(CHEMICAL OXYGEN DEMAND Value) removal has been introduced to treatment of petrochemical industries wastewater as an adaptable method and effective parameters in the process performance have been investigated. Therewith, by using commercial photocatalyst of titanium dioxide and empirical measurement of COD parameter, decrease percentage of this parameter of photocatalytic process during 90 minutes investigated via DOE&ANN method. To carry out experiments, A photocatalytic reactor with agitator used which UV-C lamps submerged within photocatalyst solution in the wastewater sample. Results of experiments at optimized conditions indicated that two models is in a good agreement with the consequences. These results demonstrated that photocatalyst concentration increase in the neutral pH state to optimized amount of 0. 84 grams per liter under unlimited conditions and 2 grams per liter under limited conditions, causes removal increase of COD to 93 and 77 percent, respectively(from 180 to 90 and 294 respectively).

Recently, adsorbed natural gas (ANG) has been considered as a low pressure and safe method for storage of natural gas, especially in vehicles. Nevertheless, the usage of the ANG storage system is hindered by the thermal effects due to both heat of adsorption and desorption during the charge and discharge processes and hence, an effective thermal enhancement is essential for the development of this technology. The purpose of this study is the investigation of transient thermal behavior of an ANG tank during charge and discharge cycles. There is a gas diffuser at the center of the tank to improve its temperature fluctuations by changing the flow direction from axial to radial. In this study, mass and energy equations were first derived and the resulting equation system was solved by implicit finite difference numerical method. By solving these equations, radial temperature and pressure distributions of adsorbent bed were obtained over time. Then, the effective parameters on the temperature fluctuations and efficiency of the ANG tank were studied. Numerical results show that the gas diffuser increases dynamic efficiency around 5% during the charge and discharge cycles. The results also show that the time of process, adsorbent bed thermal conductivity, convection heat transfer coefficient, tank geometry and dimensionless Biot and Fourier numbers are important factors on the efficiency enhancement. Also it was shown that high penetration resistance of the adsorbent bed may have a significant impact on the storage capacity and charge process time of the ANG tank.

One of the most common of measuring mass fluid flow rate through the pipes are orifice flowmeter. Orifice flowmeters work based on the fluid pressure difference before and after of the orifice which could be measured acual mass flow rate. The orifice pressure drop and the discharge coefficient are related on geometrical shape of orifice, the ratio of orifice diameter to the pipe diameter and Reynolds number of fluid flow. In this study, the performance and accuracy of an orifice flow meter for measuring the mass flow rate of cooling water in a sample thermal power plant is examined. In order to determine the water pressure drop on both sides of the discharge orifice, the orifice flowmeter with connections taken into account and fluid flow inside it is simulated. Due to the turbulent flow of water, the standard k-e turbulence model is used. The performance orifice curve has been obtained numerically and it compares with the actual performance curve orifice obtained from experimental data. This comparision shows a good match. Also the orifice discharge coefficient obtained by numerical and experimental methods and compared with values given by valid standards that indicates good agreement. The numerical analysis has determined that maximum flow velocity occurs about one orifice diameter downstream of the orifice location and in this point, velocity of flow is more than four times the average velocity of flow in the pipe entrance.

Because of the high ratio of strength to weight, composite vessels are widely used in maritime and aerospace industries. The way of composite vessels breaking under hydrostatic pressure is assignable by paying attention to the geometry and material's properties. In composite vessels, using of composite stiffeners has high complexity in manufacturing process. On the other hand, due to the low young's modulus of composite materials, usually cannot use of the materials as a stiffener. In this research, effects of using hoop stiffeners on buckling pressure of composite bodies have been studied. In this paper, mechanical manner of a composite body is studied by Finite Element Method (FEM) in two statuses (with metal stiffener and without metal stiffener). According to results, using of a metal hoop stiffener that has 3. 6 percents of the composite body weight increases buckling pressure up to 25 percents. Based on results increasing the buckling pressure of composite bodies by mounting steel hoop stiffeners added lower weight to the suite from increasing of thickness of bodies. For verification of numerical results, a composite vessel of GRP (Glass Reinforced Polymer), reinforced by a hoop stiffener mounted on inner surface has been experimentally under hydrostatic pressure to the breaking step. Finally, it was broken by 16 bar pressure. The results showed that the estimated pressure of software has a little difference with the experimental estimation that represents high accuracy of modeling process in the research.

During the GT13D gas turbine overhaul, there have been quasi-cracks in the stator blades of semi upper-end compressor rows that appeared in the grooves at the point where stator blades were attached to the roots. Also, due to the same phenomenon, the blade leading edge was damaged in the same area, which caused the replacement of a number of blades. In this paper, it has been tried to investigate these blades from different views and methods such as hardness, material, appearance, surface layers, microstructure, surface quality with SEM electron microscope and. . . The dominant mechanism in erosion of this blade and the cause of this failure is determined. The results of these studies suggest that the martensitic stainless steel blade type is hardly uniform in all parts, and there are no structural changes indicative of temperature variations. Also, the erosion and deterioration factor can not be related to the presence of external particles. Studies have shown that the occurrence of the erosion phenomenon is likely due to the flow of air from the blades

To reduce the adverse effects of cross winds on the performance of dry cooling towers in steam power plants, various methods such as installation of guide vanes cascades in wind direction have been used. This experimental investigation aims at evaluating the performance of guide vanes cascades under varying cross wind directions. For this purpose, effects of angle of flow at the entrance to the guide vanes cascade on the exiting flow quality and flow rate through the guide vanes cascade have been investigated using wind tunnel experiments. Results show that at zero degree angle of flow (with respect to the vane surface), the velocity distribution at the cascade outlet is uniform, the vanes' wake is small, and drop in the total pressure is about 2%. Moreover, with increase in the angle of flow at the entrance to guide vanes cascade (in the range 30Â ° to 60Â ° ), flow uniformity diminishes and the drop in the total pressure increases, which is indicative of degradation in the performance of the guide vanes cascade. For example, at 60Â ° angle of flow, the guide vanes cascade can only guide 20% of the total flow rate through the cascade. The results further show that for flow angles, at which cross wind strikes the back of the guide vanes cascade, installation of the cascade produces positive effects by changing the flow direction towards the cooling tower radiators, which improves the thermal performance of the radiators.

This paper divided into two parts. In the first part various type of technology for texturing of sheet rolled metal Is introduced including, shot blasting (SB), laser beam texturing (LBT), ion beam texturing, electron beam texturing (EBT), and electrical discharge texturing. Advantages and disadvantages of various type of texturing are discussed and compare with each other. In the second part of the paper, an expert system is modeling and developed for estimating surface roughness and peak count in concurrent engineering environment for electro-discharge texturing (EDT). The expert system links with A feature based CAD system in order to extract design data. Description of different size and classes of sheet rolled material is extract from CAD data base. Attributes of seventy different type of metal for work piece, eight different type of material for tools, and different type of dielectric, are stored in databases. The knowledge base is linked with CAD data base. The surface roughness and peak count and other necessary variable, are estimated. The system provides useful information for product designers and also advises manufacturing engineers to select optimum machining parameters. For validity of the expert system, out put of expert system compars with output of experimental. The results shows that estimating of machining time and cost, surface roughness and peak count of intelligent system 10 percent better than experimental. Keywords: expert system, Electro-discharge, texturing, Texture technology, laser, electron beam, ion beam

In this article a method for determining the admissible acceleration of the end-effector is presented for the suspended cable robot in the different points of the workspace. The presented acceleration analysis is different with the dynamic work space. Indeed, the dynamic work space is defined as the set of all end-effector poses satisfying the acceleration conditions. While in the proposed analysis in this paper, the allowable acceleration range of the end-effector in each direction is obtained for any point of the workspace. To this end, after deriving the kinematic equations of the four-cable suspended robot, its dynamic equations are derived using the Lagrange method. Then, on the base of the positive tension constraint in the cables and the torque constraint of the actuators, the obtained equations are simplified to obtain the simple relation between the constrains and the end-effector acceleration in such a way that the lower and upper limit of the admissible acceleration is obtained. Some simulations are done in order to present the admissible acceleration in different point of the workspace. The simulation results show that the acceleration range is in the form of the pyramid with the rhomboid base. So the allowable range of the acceleration is changed in different direction. The results obtained in this paper can be used for online trajectory planning in high speed motion of cable robot.

Three types of generator named wound rotor synchronous generator (WRSG), permanent magnet synchronous generator (PMSG) and doubly fed induction generator (DFIG) are usually used in variable speed horizontal axis wind turbines. Synchronous generator with controlled excitation voltage is a proper solution for power production in rotational speed lower than the nominal. In this paper, excitation voltage controller is designed to capture maximum energy of wind and pitch angle controller is designed to regulate the rotational speed of rotor when wind speed is over the rated value. Simulation results are verified by means of HIL (Hardware In the Loop) test setup. In this case, the function of controllers are examined in a turbulent wind condition on a simulator and the performance is analyzed. Finally, it is concluded that MPPT (Maximum Power Point Tracking) algorithm can be performed by controlling the excitation voltage of a synchronous generator in a below rated condition.

Using renewable energy sources as a solution for country⠀™s stable growth needs distinct look in topics of energy production. Agriculture industry is a general industry and it is an energy consumer that can be considered as a topic in this field. Existing a based refrigerator in farm and garden makes optimized harvesting and because it is easy to use sun radiation at these places, it can be used as a source of energy for providing refrigerator⠀™s energy. One of important needs in refrigerator, is producing continues and stable effect of refrigeration in operator while radiation release is intermittent and variable. By presentation of synthetic cycle of absorbing refrigeration, liquid refrigerant can be stored during radiation, so it can be used in other situations and as a result continues and stable effect of refrigeration can be produced. Considering collector⠀™s parabolic shape optimized temperature, 119. 6 ° C in generator is available. Optimized temperature of condenser, absorber and operator, in order equals 40, 43. 7 and-3. 2 ° C. By selecting 14bars for pressure in generator and condenser and 2bar pressure for operator and absorber, maximum coefficient of operation is 0. 178 and rate of heat transfer in generator, condenser, absorber and operator is achieved 19. 76, 7. 51, 15. 77 and 3. 51 Kw in order.

In the dynamic manipulation of objects, the aim is to throw an object by a robot to the desired target even outside the reachable workspace. In this paper, the concept of the throw-able workspace or dynamic manipulation workspace is defined as a set of points which the robot is able to throw the object at them. Thus, in order to obtain the maximum dynamic manipulation workspace which means the farthest points that object can be manipulated, it is necessary to solve the optimal throwing problem. To this end, the optimal throwing problem is defined as the optimal control problem solved using the indirect solution method based on the fundamental theorem of the calculus of variations. By applying the throwing equation as a moving boundary condition, the derived optimality conditions construct a two-point boundary value problem which its solution results in the optimal throwing. Finally, an algorithm is presented to calculate the maximum dynamic manipulation workspace. Then, simulation results are presented for a single link robot in order to evaluate the defined concept as well as the effectiveness of the proposed method for problem-solving.