S. Kamrava, M. Tatari, Yustianto Tjiptowidjojo, H. Nayeb-Hashemi
Inflatable structures are commonly used in a variety of engineering applications such as robotics, space structures, medical devices, and automotive safety devices. However, inflation in these systems often requires a non-flexible external pressurized fluid source. Integration of the pressurized fluid source and the flexible construct sacrifices some of the main advantages of the soft structures such as overall flexibility of the system, weight, and cost of fabrication. In this paper, we introduce a novel design for self-inflating structure with embedded pressurizing module. The design is based on integrating a flexible dome with a cylinder. The pressure inside the cylinder is controlled by subjecting dome to a cyclic compression, causing air exchange between the dome and the cylinder. The performance of this design is fully validated through finite element simulations using fluid structure interactions as well as experimental investigations. The results show that a higher pressure is achieved by having smaller dome height. In addition to controlling internal pressure of the cylinder, the design can be used to control the stiffness of the flexible structure such as soft robotics through pressurization. An application of this conceptual device such as pressurizing a tire is presented. This device is integrated within a tire and tire rotation as well as load on the tire have been shown to pressurize the tire. The final pressure and time to achieve maximum pressure depend on the load to the axel of the tire and tire rotational speed, respectively.
{"title":"Design and Characterization of a Flexible Self-Inflating Mechanical Structure","authors":"S. Kamrava, M. Tatari, Yustianto Tjiptowidjojo, H. Nayeb-Hashemi","doi":"10.1115/1.4054953","DOIUrl":"https://doi.org/10.1115/1.4054953","url":null,"abstract":"\u0000 Inflatable structures are commonly used in a variety of engineering applications such as robotics, space structures, medical devices, and automotive safety devices. However, inflation in these systems often requires a non-flexible external pressurized fluid source. Integration of the pressurized fluid source and the flexible construct sacrifices some of the main advantages of the soft structures such as overall flexibility of the system, weight, and cost of fabrication. In this paper, we introduce a novel design for self-inflating structure with embedded pressurizing module. The design is based on integrating a flexible dome with a cylinder. The pressure inside the cylinder is controlled by subjecting dome to a cyclic compression, causing air exchange between the dome and the cylinder. The performance of this design is fully validated through finite element simulations using fluid structure interactions as well as experimental investigations. The results show that a higher pressure is achieved by having smaller dome height. In addition to controlling internal pressure of the cylinder, the design can be used to control the stiffness of the flexible structure such as soft robotics through pressurization. An application of this conceptual device such as pressurizing a tire is presented. This device is integrated within a tire and tire rotation as well as load on the tire have been shown to pressurize the tire. The final pressure and time to achieve maximum pressure depend on the load to the axel of the tire and tire rotational speed, respectively.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87730984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research proposes a method to track a known runway image to land an unmanned aerial vehicle (UAV) automatically by finding a perspective transform between the known image and an input image in real-time. Apparently, it improves the efficiency of feature detectors in real-time, so they can better respond to perspective transformation and reduce the processing time. A UAV is an aircraft that is controlled without a human pilot on board. The flight of a UAV operates with various degrees of autonomy, either autonomously using computational-limited on-board computers or under remote control by a human operator. UAVs were originally applied for missions where human access was not readily available or where it was dangerous for humans to go. Nowadays, the most important problem in monitoring by an autopilot is that the conventional system using only the GPS sensors provides inaccurate geographical positioning. Therefore, controlling the UAV to take off from or land on a runway needs professional input which is a scarce resource. The characteristics of the newly developed method proposed in this paper are: (1) using a lightweight feature detector, such as SIFT or SURF, and (2) using the perspective transformation to reduce the effect of affine transformation that results in the feature detector becoming more tolerant to perspective transformation. In addition, the method is also capable of roughly localizing the same template in consecutive frames. Thus, it limits the calculation area that feature matching needs to work on.
{"title":"Automatically Landing an Unmanned Aerial Vehicle Using Perspective-n-Point Algorithm Based on Known Runway Image: Area Localization and Feature Enhancement With Time Consumption Reduction","authors":"Sakol Kongkaew, M. Ruchanurucks, J. Takamatsu","doi":"10.1115/1.4055081","DOIUrl":"https://doi.org/10.1115/1.4055081","url":null,"abstract":"\u0000 This research proposes a method to track a known runway image to land an unmanned aerial vehicle (UAV) automatically by finding a perspective transform between the known image and an input image in real-time. Apparently, it improves the efficiency of feature detectors in real-time, so they can better respond to perspective transformation and reduce the processing time. A UAV is an aircraft that is controlled without a human pilot on board. The flight of a UAV operates with various degrees of autonomy, either autonomously using computational-limited on-board computers or under remote control by a human operator. UAVs were originally applied for missions where human access was not readily available or where it was dangerous for humans to go. Nowadays, the most important problem in monitoring by an autopilot is that the conventional system using only the GPS sensors provides inaccurate geographical positioning. Therefore, controlling the UAV to take off from or land on a runway needs professional input which is a scarce resource. The characteristics of the newly developed method proposed in this paper are: (1) using a lightweight feature detector, such as SIFT or SURF, and (2) using the perspective transformation to reduce the effect of affine transformation that results in the feature detector becoming more tolerant to perspective transformation. In addition, the method is also capable of roughly localizing the same template in consecutive frames. Thus, it limits the calculation area that feature matching needs to work on.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90250383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Shibahara, K. Ikushima, Manami Maekawa, Ryo Ashida, Takuya Kato, A. Notsu
In recent years, ship hulls have very complicated shapes in order to reduce frictional resistance and wave resistance during navigation. In particular, in the bow and stern, curved skin plates with complex shapes are used. Line heating is used to produce such complex shapes. Line heating is a bending technique using plastic deformation due to heating. The relationship between the heat input and the deformation is nonlinear, which may lead to difficulty in making a heating plan for forming the target shape. Thus, skilled workers are necessary in line heating, and the work time and dimensional accuracy depend on their skills. Another problem is the transfer of this technique to future generations. In order to overcome these problems, automation of the line heating process has been investigated urgently. On the other hand, artificial intelligence (AI) technology has been rapidly developed in recent years. An AI system can deal with nonlinear relationships and ambiguous feature quantities, which are difficult to express mathematically. By using AI, automation of the planning of the heating line can be expected. The purpose of the present study is to obtain the optimal heat input conditions for forming an arbitrary shape in line heating. In order to accomplish this, we constructed an AI system that integrated deep layer reinforcement learning and line heating simulation. The proposed system was applied to the formation of fundamental shapes of line heating, including the bowl shape, the saddle shape, and the twisted shape. As a result, the proposed system was found to be able to generate heating plans for these shapes with fewer heating lines.
{"title":"Approach to Automation of Line Heating by Combination of Reinforcement Learning and Finite Element Method Simulation","authors":"M. Shibahara, K. Ikushima, Manami Maekawa, Ryo Ashida, Takuya Kato, A. Notsu","doi":"10.1115/1.4054475","DOIUrl":"https://doi.org/10.1115/1.4054475","url":null,"abstract":"\u0000 In recent years, ship hulls have very complicated shapes in order to reduce frictional resistance and wave resistance during navigation. In particular, in the bow and stern, curved skin plates with complex shapes are used. Line heating is used to produce such complex shapes. Line heating is a bending technique using plastic deformation due to heating. The relationship between the heat input and the deformation is nonlinear, which may lead to difficulty in making a heating plan for forming the target shape. Thus, skilled workers are necessary in line heating, and the work time and dimensional accuracy depend on their skills. Another problem is the transfer of this technique to future generations. In order to overcome these problems, automation of the line heating process has been investigated urgently. On the other hand, artificial intelligence (AI) technology has been rapidly developed in recent years. An AI system can deal with nonlinear relationships and ambiguous feature quantities, which are difficult to express mathematically. By using AI, automation of the planning of the heating line can be expected. The purpose of the present study is to obtain the optimal heat input conditions for forming an arbitrary shape in line heating. In order to accomplish this, we constructed an AI system that integrated deep layer reinforcement learning and line heating simulation. The proposed system was applied to the formation of fundamental shapes of line heating, including the bowl shape, the saddle shape, and the twisted shape. As a result, the proposed system was found to be able to generate heating plans for these shapes with fewer heating lines.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90516364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lattice structure metamaterials generally exhibit better stiffness and/or tunable properties than natural materials. They have important applications in mechatronics and tissue engineering areas. In this work, we demonstrate crystal structure-inspired body-centered cubic (BCC)-lattice architected structures using different acrylate-based polymer materials to study the mechanical response in large deformation. Rigid BCC lattice metamaterials manifest outstanding recovery properties after undergoing multi-cycle compression. With appropriate cell wall thickness, the lattices have the capacity to recover their original shape and maintain a degree of stiffness. In further exploration, we combined mechanical tests and digital image correlation to elaborate on the deformation mechanisms. The digital image correlation (DIC) proves that displacement discrepancy exists in local positions. We propose hourglass and twist models to describe the buckling-induced pattern transformation which occurs during cyclic compressive deformation using simulation.
{"title":"Modeling Three-Dimensional-Printed Polymer Lattice Metamaterial Recovery After Cyclic Large Deformation","authors":"Siqi Wu, Erol Sancaktar","doi":"10.1115/1.4055466","DOIUrl":"https://doi.org/10.1115/1.4055466","url":null,"abstract":"\u0000 Lattice structure metamaterials generally exhibit better stiffness and/or tunable properties than natural materials. They have important applications in mechatronics and tissue engineering areas. In this work, we demonstrate crystal structure-inspired body-centered cubic (BCC)-lattice architected structures using different acrylate-based polymer materials to study the mechanical response in large deformation. Rigid BCC lattice metamaterials manifest outstanding recovery properties after undergoing multi-cycle compression. With appropriate cell wall thickness, the lattices have the capacity to recover their original shape and maintain a degree of stiffness. In further exploration, we combined mechanical tests and digital image correlation to elaborate on the deformation mechanisms. The digital image correlation (DIC) proves that displacement discrepancy exists in local positions. We propose hourglass and twist models to describe the buckling-induced pattern transformation which occurs during cyclic compressive deformation using simulation.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75536227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A surrogate model-based multi-objective design optimization methodology using a nondominated sorting genetic algorithm is used to maximize the power output and efficiency of an axial flow turbine. A set of high-fidelity data obtained from ANSYS-CFD simulations on space-filling samples is used for developing a surrogate model. The methodology uses (i) a Latin hypercube experimental design for selecting space-filling samples, (ii) a genetic algorithm for determining parameters of a Kriging model, and (iii) axial gap, tip clearance, and rotation angle of nozzle profile of turbine as predictor variables. Flow in the turbine is characterized by the presence of jet and wake flow, shock in the rotor blade flow passage, and tip clearance vortex. Study shows that (i) the axial gap controls the mixing of the jet and the wake flows and provides proper blade incidence which reduces the shock strength in the rotor blade flow passages and (ii) an optimum sized tip clearance vortex controls tip clearance leakage. The optimization provided a set of Pareto-optimal solutions that are nondominated in terms of power and efficiency. Verification of a selected design configuration from the Pareto-optimal solution using computational fluid dynamics (CFD) analysis showed that the process of optimization has been able to fine-tune the axial gap and the tip clearance.
{"title":"Multi-Objective Optimization of an Axial Flow Turbine Design Using Surrogate Modeling and Genetic Algorithm","authors":"Aji M. Abraham, S. Anil Lal","doi":"10.1115/1.4054429","DOIUrl":"https://doi.org/10.1115/1.4054429","url":null,"abstract":"\u0000 A surrogate model-based multi-objective design optimization methodology using a nondominated sorting genetic algorithm is used to maximize the power output and efficiency of an axial flow turbine. A set of high-fidelity data obtained from ANSYS-CFD simulations on space-filling samples is used for developing a surrogate model. The methodology uses (i) a Latin hypercube experimental design for selecting space-filling samples, (ii) a genetic algorithm for determining parameters of a Kriging model, and (iii) axial gap, tip clearance, and rotation angle of nozzle profile of turbine as predictor variables. Flow in the turbine is characterized by the presence of jet and wake flow, shock in the rotor blade flow passage, and tip clearance vortex. Study shows that (i) the axial gap controls the mixing of the jet and the wake flows and provides proper blade incidence which reduces the shock strength in the rotor blade flow passages and (ii) an optimum sized tip clearance vortex controls tip clearance leakage. The optimization provided a set of Pareto-optimal solutions that are nondominated in terms of power and efficiency. Verification of a selected design configuration from the Pareto-optimal solution using computational fluid dynamics (CFD) analysis showed that the process of optimization has been able to fine-tune the axial gap and the tip clearance.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76858864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bulk modulus has wide applications in well engineering, seismic exploration, waste reinjection, and predicting pore pressure in carbonate reservoirs. However, there is no easy way to obtain accurate values for the effective bulk modulus of rocks. Practically, researchers use rigorous, costly, and time-consuming experiments on core samples. But, stress release and changing rock’s environment have affected the accuracy of results. Also, it is impossible to get accurate values of the effective bulk modulus from theory without accounting for the deformation of microcracks in the rock. Existing models do not consider the presence of microcracks because of the inability to define the positions of cracks relative to one another. Thus, earlier studies introduced approximations to define the upper and lower bounds of values. This study aims to overcome this limitation by accounting for the fluids in the microcracks, apart from those in stiff pores. From the product of the surface area and thickness of the fluid in the microcracks, the authors generated proportionality between the volume of fluid and that of the grain and obtained expression for the crack porosity. Then analytical and numerical techniques were applied to obtain models for the effective bulk modulus. The results show that the presence and magnitude of inclusions reduce the effective bulk modulus significantly. This was validated by a finite element analysis (FEA) using the FEATool run in matlab. In addition, higher volume of fluids in the microcracks makes the rate of change of the bulk modulus with the porosity to be higher.
{"title":"An Equation for the Bulk Modulus of Composites Derived From the Effective Medium Theory","authors":"Roland I. Nwonodi, A. Dosunmu, E. Okoro","doi":"10.1115/1.4055628","DOIUrl":"https://doi.org/10.1115/1.4055628","url":null,"abstract":"\u0000 Bulk modulus has wide applications in well engineering, seismic exploration, waste reinjection, and predicting pore pressure in carbonate reservoirs. However, there is no easy way to obtain accurate values for the effective bulk modulus of rocks. Practically, researchers use rigorous, costly, and time-consuming experiments on core samples. But, stress release and changing rock’s environment have affected the accuracy of results. Also, it is impossible to get accurate values of the effective bulk modulus from theory without accounting for the deformation of microcracks in the rock. Existing models do not consider the presence of microcracks because of the inability to define the positions of cracks relative to one another. Thus, earlier studies introduced approximations to define the upper and lower bounds of values. This study aims to overcome this limitation by accounting for the fluids in the microcracks, apart from those in stiff pores. From the product of the surface area and thickness of the fluid in the microcracks, the authors generated proportionality between the volume of fluid and that of the grain and obtained expression for the crack porosity. Then analytical and numerical techniques were applied to obtain models for the effective bulk modulus. The results show that the presence and magnitude of inclusions reduce the effective bulk modulus significantly. This was validated by a finite element analysis (FEA) using the FEATool run in matlab. In addition, higher volume of fluids in the microcracks makes the rate of change of the bulk modulus with the porosity to be higher.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74133129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. C. Robinson, Norman H. Garrett, Darrick Vaseleniuck, M. Uddin
The poppet valve is by far the most widely used in cylinder head design of internal combustion (IC) engines; however, poppet valves themselves create significant flow restrictions during both the intake and exhaust strokes, thus causing a reduction in volumetric efficiency that affects overall engine performance. By removing the restrictive poppet valve from the flow path of air into and out of the cylinder head and allowing air to flow unobstructed, any given IC engine can achieve greater volumetric efficiency and higher specific output. The Vaztec ECOREV rotary valve system utilizes straight-cut flow passages that reduce such restrictions. This rotary valve system is designed to be directly driven by the crankshaft, thereby replacing the camshaft and poppet valve system altogether. This paper will primarily explore the differences in flow characteristics between this rotary valve and a conventional poppet valve cylinder head using both computational fluid dynamics (CFD) and flow bench data. Both configurations will be evaluated on the same single-cylinder four-stroke internal combustion engine. CFD simulations were run at multiple valve opening positions on each cylinder head configuration for both intake and exhaust cycles to validate the CFD process against flow bench test data for both cylinder head designs. The CFD was performed in 3D using hexahedral meshing and steady-state Reynolds-averaged Navier–Stokes (RANS) turbulence models. Comparison between the two engine configurations will include both intake and exhaust airflow rates as well as discharge coefficients and overall flow field evaluation using numerous scalar and vector properties.
{"title":"A Computational Fluid Dynamics Investigation Comparing the Performance of an Alternative Valvetrain Design Against a Traditional Poppet Valvetrain","authors":"A. C. Robinson, Norman H. Garrett, Darrick Vaseleniuck, M. Uddin","doi":"10.1115/1.4054966","DOIUrl":"https://doi.org/10.1115/1.4054966","url":null,"abstract":"\u0000 The poppet valve is by far the most widely used in cylinder head design of internal combustion (IC) engines; however, poppet valves themselves create significant flow restrictions during both the intake and exhaust strokes, thus causing a reduction in volumetric efficiency that affects overall engine performance. By removing the restrictive poppet valve from the flow path of air into and out of the cylinder head and allowing air to flow unobstructed, any given IC engine can achieve greater volumetric efficiency and higher specific output. The Vaztec ECOREV rotary valve system utilizes straight-cut flow passages that reduce such restrictions. This rotary valve system is designed to be directly driven by the crankshaft, thereby replacing the camshaft and poppet valve system altogether. This paper will primarily explore the differences in flow characteristics between this rotary valve and a conventional poppet valve cylinder head using both computational fluid dynamics (CFD) and flow bench data. Both configurations will be evaluated on the same single-cylinder four-stroke internal combustion engine. CFD simulations were run at multiple valve opening positions on each cylinder head configuration for both intake and exhaust cycles to validate the CFD process against flow bench test data for both cylinder head designs. The CFD was performed in 3D using hexahedral meshing and steady-state Reynolds-averaged Navier–Stokes (RANS) turbulence models. Comparison between the two engine configurations will include both intake and exhaust airflow rates as well as discharge coefficients and overall flow field evaluation using numerous scalar and vector properties.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82100392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to find how fires and explosions can occur in enclosed spaces where electrical transformers are installed and to investigate the consequences of the damages to the surrounding areas caused by these accidents. This study began with the collection of a mineral oil waste sample from an indoor substation transformer in Riyadh, Saudi Arabia. This sample was analyzed to determine its composition. Results revealed that 30 components ranging from C6 to C30 were detected in the sample. The mixture flammability limits, calculated using Le Chatelier rules and found to be 0.97 and 6.56, indicated that the vapor mixture for the waste oil sample was not flammable at 25 °C and 1 atm. Consequence analysis was used to predict the outcome of fire and explosion events based on a transformer with a capacity of 1100 liters. The peak overpressure generated by an explosion was estimated to be 80.97 kPa. Moreover, the thermal radiation produced by various types of fires was estimated as a function of the distance from the accident center. The thermal flux from a boiling liquid expanding vapor explosion (BLEVE) was 99.8 kW/m2, which is greater than that from jet and pool fires. The probability of an individual suffering injury or dying as a result of exposure to fire and/or an explosion was estimated using dose-response models. The results showed that the peak overpressure produced by an explosion can cause severe damage within 20 m of the explosion center. However, the results also showed that there is a 100% probability of the thermal radiation from a BLEVE causing fatalities up to a distance of 140 m. The risk due to the fragmentation of the transformer tanks was also assessed, and a majority of fragments would land within a range of 111.2 m.
{"title":"Fire and Explosion Risks and Consequences in Electrical Substations—A Transformer Case Study","authors":"M. El-Harbawi","doi":"10.1115/1.4054143","DOIUrl":"https://doi.org/10.1115/1.4054143","url":null,"abstract":"This study aims to find how fires and explosions can occur in enclosed spaces where electrical transformers are installed and to investigate the consequences of the damages to the surrounding areas caused by these accidents. This study began with the collection of a mineral oil waste sample from an indoor substation transformer in Riyadh, Saudi Arabia. This sample was analyzed to determine its composition. Results revealed that 30 components ranging from C6 to C30 were detected in the sample. The mixture flammability limits, calculated using Le Chatelier rules and found to be 0.97 and 6.56, indicated that the vapor mixture for the waste oil sample was not flammable at 25 °C and 1 atm. Consequence analysis was used to predict the outcome of fire and explosion events based on a transformer with a capacity of 1100 liters. The peak overpressure generated by an explosion was estimated to be 80.97 kPa. Moreover, the thermal radiation produced by various types of fires was estimated as a function of the distance from the accident center. The thermal flux from a boiling liquid expanding vapor explosion (BLEVE) was 99.8 kW/m2, which is greater than that from jet and pool fires. The probability of an individual suffering injury or dying as a result of exposure to fire and/or an explosion was estimated using dose-response models. The results showed that the peak overpressure produced by an explosion can cause severe damage within 20 m of the explosion center. However, the results also showed that there is a 100% probability of the thermal radiation from a BLEVE causing fatalities up to a distance of 140 m. The risk due to the fragmentation of the transformer tanks was also assessed, and a majority of fragments would land within a range of 111.2 m.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91043368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Measurements of whole-body vibration are fundamental to access and evaluate comfort levels and possible injury development in the human being. International standards such as ISO 2631 and ISO 10326 are dedicated to the measurement and validation of mechanical systems to access vibration levels. Nowadays, the traditional measurement devices require multiple components and so hence become highly bulky, do not allow autonomous data recording, and are expensive. Following the previously mentioned standards, the present research is focused on the design and validation of a new and economic whole-body vibration measurement device. The developed device, besides being capable to measure the whole-body vibration, allows the user to select multiple sample ratings, is capable to record data on a µSD card, is easily moved and adapted, and is autonomous and low cost. This device is composed of three main components: a tri-axial accelerometer, a protective metal case, and semi-rigid rubber disc. Shaker tests were conducted to evaluate the measurement capability of the whole system and the influence of each component on the vibration measurements. This article will introduce the design and development steps for the proposed system. Concerning the validation phase, its results will be discussed and analyzed.
{"title":"Design, Development, and Validation of a Whole-Body Vibration Measurement Device","authors":"P. Silva, E. Seabra, J. Mendes","doi":"10.1115/1.4055191","DOIUrl":"https://doi.org/10.1115/1.4055191","url":null,"abstract":"\u0000 Measurements of whole-body vibration are fundamental to access and evaluate comfort levels and possible injury development in the human being. International standards such as ISO 2631 and ISO 10326 are dedicated to the measurement and validation of mechanical systems to access vibration levels. Nowadays, the traditional measurement devices require multiple components and so hence become highly bulky, do not allow autonomous data recording, and are expensive. Following the previously mentioned standards, the present research is focused on the design and validation of a new and economic whole-body vibration measurement device. The developed device, besides being capable to measure the whole-body vibration, allows the user to select multiple sample ratings, is capable to record data on a µSD card, is easily moved and adapted, and is autonomous and low cost. This device is composed of three main components: a tri-axial accelerometer, a protective metal case, and semi-rigid rubber disc. Shaker tests were conducted to evaluate the measurement capability of the whole system and the influence of each component on the vibration measurements. This article will introduce the design and development steps for the proposed system. Concerning the validation phase, its results will be discussed and analyzed.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84316287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ashley C. Yarbrough, Gregory A. Harris, Gregory T. Purdy, Nicholas Loyd
The growth of technology in the manufacturing domain is compelling industry to digitally transform with little to no guidance on what constitutes value-added and nonvalue-added data and information. However, the Toyota production system (TPS) approach, which has proven successful for decades in identifying wastes in physical manufacturing processes, can provide some insights. Extensive research has been conducted on the history of Toyota and the concepts and tools of the TPS, but there is no documentation of how Taiichi Ohno approached problems and developed the classification of wastes (the 7 Wastes) which led to the concepts and tools for continuous improvement that are collectively called the TPS. This article deconstructs literature on Ohno and the Toyota story to reconstruct the mental model that Ohno used to identify and categorize physical production waste in Toyota’s manufacturing operations. The mental model attributed to Ohno proposed in this work is then generalized into a framework for identifying and eliminating both physical and nonphysical wastes in systems. Manufacturing companies and researchers can utilize the framework to foster the same thinking that Ohno used to identify nonvalue-added activities in production processes. Applying the described framework to data and information flows will allow for the discovery of wastes that were once hidden and will lead to the development of tools for improving the data and information needed to support manufacturing in a Smart Manufacturing environment.
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