جستجوی مقالات مرتبط با کلیدواژه « Simulation » در نشریات گروه « مواد و متالورژی »

Small and Medium Enterprises (SMEs) face significant challenges in the global competitive market. An approach SMEs adopt to meet these challenges is implementing lean principles through the framework of lean implementation. Although some lean implementation frameworks have been introduced, previous research indicates that SMEs often need assistance applying this framework. This is caused by the need to adjust the lean implementation framework, which is considered limited by the resources owned by SMEs. Therefore, further research discusses adjusting the lean implementation framework and SME resources needed to improve operational performance. This study emphasizes the need for a lean implementation framework tailored to SMEs' scale and resources to reduce waste and improve operational efficiency. The lean implementation framework is developed by combining the lean implementation framework with the plan do check act (PDCA) approach and simulation to produce continuous improvements. The framework development stage evaluates the existing lean implementation framework based on previous research and SME resources. Furthermore, the framework that has been evaluated is grouped based on the plan, do, check, and action stages. This activity is carried out to ensure that lean implementation activities are a continuous improvement cycle. The final stage is adding simulation steps to the do and check stages to evaluate proposed improvements. The proposed framework was tested through a case study at Batik SME. The results showed the benefits and effectiveness of the proposed framework in the form of a 12.9-day reduction during work completion and an increase of 18.3% in the operator's utility.

In this study, the effects of changing die angle on drawing force during cold drawing of a 410 stainless steel tube is evaluated. For this purpose, simulation of the process by Abaqus software was performed and the results were compared with the experimental findings. By applying Johnson and Cook's equation the flow behavior of the steel was also assessed during cold drawing., Ring compression tests were performed to determine the coefficient of friction at die-tube and tube-plug interfaces. Furthermore, strain distribution during the process was considered to evaluate the mechanical behavior of the steel. An essential aspect of the work was to estimate the required drawing force, by lower and upper-bound theories. It is illustrated that the lowest drawing force is obtained at the half die angle of 16°. At this angle drawing force of 164.6 KN was estimated by simulation. Experimental results at half die angle of 16° indicated a drawing force of 175.1 KN which illustrates about 5% discrepancy with simulated results. Also, the radial strains at this die angle had the highest value in comparison with other half die angles of 12 and 14 degrees. The highest amount of strain was observed in axial direction of the drawing process at the half die angle of 16°. Lowest values of residual stresses were developed at this die angle.

The height of buildings is one of the main features of urban configuration that affects energy consumption. However, to our knowledge, the complexity of relationships between the height parameters and energy use in urban blocks is poorly understood. In this context, the present study investigates the effect of the height distribution of buildings located in a residential complex on the energy consumption required for cooling and heating. This research simulates different possible layouts through computational software. For this purpose, first, the density of a residential complex was determined based on the rules and regulations of Tehran city and according to the site dimensions and certain site coverage. Then, the required building density was distributed in different layouts based on their diversity at different heights. The product of this stage involved 7 different layouts in which the height varied from 1 floor to the maximum number calculated in each part of the simulation. In the next step, the annual energy consumption for cooling and heating the complex was calculated for each of these layouts and compared with each other. The parametric generative model was created in the Grasshopper plugin from Rhino software, and the energy consumption was evaluated with the Honeybee plugin over one year. Also, the research findings were validated through DesignBuilder software using the EnergyPlus engine. The results of the energy simulation indicate that the height distribution of the blocks can have a significant effect on energy consumption. In the optimal case, proper layout reduces the annual cooling and heating energy consumption by 28 % and 13 %, respectively. Therefore, achieving an optimal value for each of the cooling and heating loads depends on the specific priorities and conditions of the design project. If the design project's priority is to reduce heating energy consumption, increasing the height and distributing the floors evenly between the blocks is a better answer. However, if the priority is to mitigate cooling energy consumption, the optimal layout can include low-rise blocks and a single very high-rise block.

Around the globe, a 60 % increase in energy demand is predicted to occur by the end of the year 2030 due to the ever-increasing population and development. With a registered temperature up to 50 °C in August 2020, which is classified as one of the hottest regions in the world, the demand for cool temperatures in Gabes-Tunisia to achieve the thermal comfort of people ensuring the product storage has become more and more intense. Removing heat from buildings represents the most extensive energy consumption process. In this paper, an absorption-refrigeration system driven by solar energy is proposed. A parametric simulation model is developed based on the TRNSYS platform. A comparison between different models for global radiation calculation and experimental meteorological data was carried out. It has been proven that the Brinchambaut model seems to be the most convenient in describing the real global radiation, with an error of up to 3.16 %. An area of 22 m² of evacuated tube solar collector ensures the proper functioning of the generator and achieves a temperature up to 2 °C in the cold room.

Backscatter radiography as a technique can successfully be applied for predicting the pipeline bursting and casing failure. A valid numerical technique will allow predicting these issues without needing to access the outside of the pipelines. Furthermore, this technique has the ability to estimate the shape and depth of damages. It is normally preferred to apply non-destructive testing (NDT) methods which can monitor the status of a pipeline from the internal surface of it without needing to access both sides of it depending on various locations of pipe such as underground or submarine. In the current study, backscatter radiography as an applicable and NDT method to detect locations with potential for pipeline bursting or casing failure was carefully investigated using the Monte Carlo simulation tool. The data obtained by the simulation process showed that backscatter radiography could detect deformations, corroded areas, depositions, creation of load on the casing, lacking proper cementation, excessive pressure inside the pipelines, and other factors which may increase the risk of pipelines bursting or casing failure (in-situ and online) with an acceptable accuracy.

Flexible and printed electronics have been widely applied due to their low cost, scalability in manufacturing, and usability in biosensors as well as wearable electronics. However, there are some limitations on fabrication of these devices including thermal limitations. Thermal constraints are of significance since ion implantation at high temperatures is one of the most important stages of fabrication; therefore, despite these limitations, fabrication of flexible BJT is practically impossible through conventional methods. In this study, copper oxide was used for the collector and emitter area of Double Heterojunction Bipolar Transistor (DHBT) due to the low-temperature deposition of copper oxide through the printing method, and the ability to adjust the doping according to the deposition conditions. DC and high-frequency specifications of two transistors with PNP and NPN structures were simulated using two-dimensional semiconductor simulator atlas module of SILVACO software.

Considering slab method, a three-dimensional analytical model was adopted to evaluate the rolling pressure, force and torque in symmetrical wire flat rolling. Due to the effectiveness of the shear friction model to express the frictional state in the bulk metal forming, thus, it was used to define in slab formulation. In this paper, the plains strain condition no longer is valid and, the strain on z direction must also be taken into account in calculations. The resultant differential equations were solved numerically by Rung Kutta method and MATLAB software. It was concluded that as shear factor rises in the range of o.4

The effect of solar collector configurations on the thermal efficiency of an active solar water heater was investigated using TRNSYS in this study. Two versions of a solar heater were formulated on the basis of serpentine and riser-header flat plate configurations. Both models were simulated based on the same parameters and weather conditions. Besides, in accordance with clear sky and cloudy sky conditions, a parametric analysis was performed to determine the impact of varying parameters on the thermal efficiency of the two models. The results showed that the serpentine-based device model provided about 2.62 % more usable thermal energy than the riser-header configuration. In addition, both models demonstrated the same response and sensitivity to changes in the collector area and the volume of the tank. However, on a cloudy day, the efficiency of serpentine showed a significant improvement and sensitivity to flow variance with an efficiency gap of about 30 % to the riser header configuration.

The combustion chamber's internal refractory in Imam Khomeini Oil Refinery Company (IKORC) was damaged in several parts, requiring operating conditions and re-inspecting the design of the combustion chamber using CFD. Simplify the combustion chamber 3D simulation, decrease in the number of calculations, the symmetry principle was applied in the simulation. The results, independent of the mesh network, were investigated via increasing the mesh nodes. The one-stage, two-stage, multi-stage and overall mechanisms, which were designated, were examined and compared to actual measured data and a calculation error of less than 8% was obtained. Ultimately, selecting overall mechanisms, the simulation results, streams mixing and length of the chamber were scrutinized, and as a result, the current design was approved. The temperature and velocity of the flows in the combustion chamber were investigated. In the combustion chamber, the farther we are from the burners, the more uniform the velocity and temperature profiles also become as the wall temperature increases. The rate of combustion reaction was evaluated with the temperature of different points in the combustion chamber. The results showed that the combustion chamber wall's temperature is in the appropriate range and has not suffered any thermal damage. Unlike the combustion chamber wall, the burner wall (at the mixing point) has an unauthorized temperature; there is the possibility of thermal damage that can be eliminated by changing the number of currents. Unsuitable thermal profiles also showed large amounts of oxygen in the exhaust gas indicated that the steam boiler performance is far from the optimal condition and specific changes would be required in the air streams. Streamline demonstrated that the primary air stream was more effective for decreasing CO and NOX amounts in the outlet stream. The secondary air stream was also significant to prevent thermal damage to the internal coating and reduce safety hazards.

Building information modeling (BIM) has attracted considerable interest in the area of 4D simulation. The performance and benefits of the 4D simulation can be affected by different factors, such as the organizational integration of the teams involved in the project and the models’ content, which is recognized as the maturity level of BIM. Despite the various advantages of implementing 4D BIM and the significance of obtaining the full potential of 4D simulation, there is a scant number of researches that have considered this issue. Thus, this study aims not only to assess the relationship between the performance of 4D simulation and different maturity levels but also to clarify the required Level of Development (LOD) and maturity level in BIM application to synchronize the BIM implementation process with its expected benefits. For this purpose, the differences in gained benefits of implementing 4D BIM in various projects, which had different BIM maturity levels, were examined. The results showed that promoting the integration of the BIM implementation process, considering suitable LOD for modeling, and clarifying the expectation from different parts of a project lead to an enhancement in the performance of BIM 4D simulation.

This article is devoted to the photovoltaic system simulation. Photovoltaic systems operate in different conditions such as changing solar irradiance and environmental temperature. Analysis of the existing methods for photovoltaic system simulation was carried out in this paper. The formal model of the electricity consumption system was developed, which included the photovoltaic system and the electrical storage system. The expediency of using simulation modeling tools in the design of solar panel optimization tools was shown by application of maximum power point tracking methods. The developed software provides the ability to build current-voltage and high-voltage characteristics of solar cells at different values of the intensity of solar radiation and temperature.. The voltage and load current differ up to 50% from the voltage and current of the operating point of the solar panel, which is set to the optimal value using maximum power point tracker. The architecture of the software extends the capabilities of simulation modeling of systems based on solar panels. The optimizer model block along with the implementation of the maximum power point tracking algorithm can be further refined by using more sophisticated algorithms. The developments are innovative and their practical implementation will have a significant impact on the energy security of countries

Rolling is a common method for production of metallic parts in various shapes and sizes. In this method, the raw material placed between two rigid rolls until take the shape and size. There are two rolling methods, hot rolling and cold rolling. To achieve higher mechanical properties, and better surface quality and dimensional accuracy, the hot rolled sheets undergo the cold rolling process. The friction between the metal and rolls affects the forming process, increase the required load for forming, reduce the surface quality and increase the wear of tools. The simulation of rolling process will be helpful to improve the forming procedure and quality of products. In this research, the Finite Element method is used to model, simulate and analysis the rolling process of St 37 steel sheets in sticky friction plane strain conditions. Because of stress strain behavior of material during the forming process and increase of frictional stress due to forming process, the analysis of forming load between the contact surface of rolls and sheet are shown by simulation. Finally, simulation of forging process as a friendly tool can reduce the scrap rate, tools wear and environmental effects of scraps.

In the process of extracting oil and gas from hydrocarbon reservoirs, the formation of depositions inside pipes, fittings, and storage tanks, not only accelerates corrosion but also reduces a significant volume of operating capacities. The most critical step in solving the problem of deposition formation is their early and timely detection. In industries, internal surfaces of the pipeline are usually inspected by nondestructive testing (NDT) methods. The detection of depositions should operationally be difficult if there were special conditions for accessing the back of pipelines. Therefore, a suitable method is encouraged to detect deposition in the pipes and tubes when one side or a small part of them is accessible. In this paper, the Monte Carlo simulation tool was applied to use backscatter radiography (as an NDT inspection technique) for in-situ detection of depositions inside the metallic pipelines. In fact, the simulation process shows the correctness and efficiency of the backscatter radiography technique. It would determine some significant factors such as photon energy, angle of irradiation, or location of detectors which affect the design before experiment. The results showed that backscatter radiography as a viable technique could properly detect the location of depositions inside the pipes.