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Gas sensitive metal oxide layers used in fabrication of resistive gas sensors are prepared by different deposition techniques. The technical data reported on some basic and practically important specifications of these devices, although fabricated based on the same gas sensitive oxide, are anomalously different. The influence of the fabrication technique used for the deposition of the gas sensitive layer on determination of the significant specifications of the transient response of a resistive gas sensor is experimentally investigated for the first time. ZnO and SnO2 layers were prepared by LPCVD, PVD, EPD and powder pressing techniques. Prototype gas sensors based on these layers were fabricated. The transient responses of these devices to a step change in the composition of the surrounding atmosphere were recorded and compared. It was shown that the thickness, porosity and pore micro-structure of the gas sensitive layer are the most effective parameters in determination of the transient response. The relationship between these parameters and the temporal variation of the electrical conductivity of the gas sensitive layer was qualitatively analyzed. Oxide layers of higher porosity resulted in gas sensors of faster response, but response time increased with the thickness of these gas sensitive layers. The sensors produced by EPD technique demonstrated the fastest responses while those produced by CVD were the slowest among the samples investigated.

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Aims: Presenting practical strategies to enhance the quality of temporary housing and elucidating the role of prefabrication and semi-prefabrication on achieving efficient architectural goals. Outlining the prefabrication and semi- prefabrication process are among the main aims of the research.

Methods: In this study, a combination of descriptive-analytical and exploratory methods was employed to examine specialized texts in the field of temporary housing design and the implemented examples in both domestic and international contexts. The study also investigated innovative approaches to semi-prefabricated construction. The main objective was to investigate and extract design approaches and indicators for temporary housing. Questionnaires were distributed to experts in the field of temporary housing design and implementation.

Findings: According to the research findings, attention to user privacy (as a people-centric component) with an average rank of 5.14, resistance of materials against earthquakes and fires (as a materials-centric component) with an average rank of 4.03, and ultimately, the utilization of innovative prefabrication and semi-prefabrication methods (as a design-centric component) with an average rank of 3.44 play the most significant role in enhancing the quality of temporary housing

Conclusion: From the standpoint of experts, there is a greater emphasis on material-centric and people-centric approaches in the design of temporary housing, while design-centric approaches and their components are deemed less significant by expert groups. Consequently, by utilizing the existing indicators within the design-centric component and enhancing the qualitative aspects of its strategies (including the incorporation of innovative semi-prefabrication methods), the quality of temporary housing can be elevated.

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Aims: The construction industry is one of the largest industries in the world and one of the most important economic pillars of a country. Throughout history, problems in this field have led human societies to find new solutions. Among today's problems in this field, we can mention the wastage of materials and energy, very high costs, and failure to complete projects on time, which is especially evident in large government projects.

Methods: In terms of methodology, this research has a qualitative nature in which qualitative methods are used. The main results of the research have been achieved by using the tools of library studies, analyzing the documentaries, and interviews with experts.

Findings: The research findings show that the use of new construction technologies and methods can take an effective step in improving the quality of architectural products. The present research provides a method to upgrade the construction industry by recognizing and extracting quantifiable qualities in architectural product production. For this purpose, the integration of software and hardware technologies is emphasized for industrialization and industrial construction.

Conclusion: The results of the research show that the integration of building information modeling technology and prefabrication is an effective step to optimize large government projects. Reducing the time and cost of construction, it increases the satisfaction of users and increases safety, and finally, it helps to improve the quality of the architectural product. The conclusion of the article emphasizes the role of prefabrication in meeting highperformance architecture and energy-efficient architecture and planning.
 

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Due to unique properties, lattice composite structure are used extensively in aviation, marine and automotive industry. In this research, experimental and numerical investigation of the free vibration of composite sandwich plates with triangular grid has been studied. For the fabrication of this plates, silicone mold, filament winding, and hand lay-up method were used. Stiffened plates and simple plates are fabricated, separately. Then, composite sandwich plates with triangular grid were created by attaching the two parts together. The modal test is done on the plates and natural frequencies have been extracted.The comparison of numerical and experimental results showed that there is a good agreement between them. By using Taguchi method, a parametric study was performed on the vibrational behavior of sandwich plates with triangular cores via three parameters that such as stiffeners’ number, stiffener thickness and skin thickness. The results show that the natural frequency of sandwich plates with triangular grid has a most sensitive to the stiffener thickness, and least sensitive to stiffeners’ number. The sensitivity of natural frequency is almost identical to stiffener thickness and skin thickness.To evaluate the efficiency of sandwich plates with triangular grid, the natural frequency of sandwich plates are compared with simple plates in the different boundary condition. The results show that the natural frequency of sandwich plates with the triangular grid is 133% and 138% higher than an equivalent simple shell at free and clamp boundary condition, respectively.

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Due to unique properties, grid stiffened composite cylinder shells are used extensively in aviation, marine and automotive industry. In recent decades, several studies are done to predict the critical buckling load of grid stiffened composite cylinder shells without breakdown or failure. Vibration Correlation Technique (VCT) is one of the most important non-destructive methods that based on nonlinear vibration analysis. The aim of this research is the prediction of the critical buckling load of stiffened composite cylinder shells with lozenge grid by using VCT. For this purpose, linear and nonlinear vibration analysis of composite cylindrical shells were performed in different compressive loads by using finite element software ABAQUS, firstly. In the next step, linear buckling critical load was determined by using numerical methods. Then, non-linear critical buckling load of grid stiffened composite cylinder shells was predicted by using VCT. To validate the results of VCT, five composite cylindrical shells were fabricated by using filament winding method with same conditions and was placed under axial compression test. Finally, the critical buckling load was measured experimentally. The results show that the difference between the critical buckling load of VCT with experimental buckling load is less than 3%. This subject implies that VCT is suitable for prediction of critical buckling load of stiffened composite cylinder shells with lozenge grid with very high accuracy.

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These days, societies' need for energy increased due to the expansion of societies, industries, and technology. The production of electricity from renewable energy sources such as solar energy, which does not harm the environment and has little pollution, has attracted the attention of many researchers and engineers. This article will present a new plan for the dual polar axis solar tracker, its design and construction in laboratory dimensions, and the experimental evaluation of its performance using the open-loop control method. For this purpose, after examining the advantages and disadvantages of the previous designs, a new and different conceptual design for the tracker is proposed. Among the features of the proposed tracker, we can point out the ability to combine, install and operate quickly and easily, the self-locking feature, and the ability to rotate 360 ​​degrees around both axes. This tracker has no restrictions for use in different geographical areas, including areas near the North or South Pole and in the early and late hours of the day when the direction of the sun's radiation is strongly inclined. In the following, the detailed design of the proposed detector and the presentation of the open-loop control method will be discussed. Finally, by conducting experimental tests, the production power of the proposed detector is evaluated in comparison with a fixed solar panel. Based on the results, the electricity energy produced from the proposed solar tracker is 49% more than the fixed solar panel.