Mechanical Engineering Letters最新文献

{"title":"Development of combustion gas measurement systems for micro-rocket torch using a diode laser sensor","authors":"Yuya Hirayama, Shinichiro Ogawa","doi":"10.1299/mel.23-00261","DOIUrl":"https://doi.org/10.1299/mel.23-00261","url":null,"abstract":"","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"04 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127257500","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}

{"title":"Robust optimization of structures subjected to frictionless unilateral contact with uncertain initial gaps","authors":"Y. Kanno","doi":"10.1299/mel.20-00224","DOIUrl":"https://doi.org/10.1299/mel.20-00224","url":null,"abstract":"This short paper studies a robust optimization problem of a structure subjected to frictionless unilateral contacts. We suppose that initial gaps possess non-probabilistic uncertainty, and attempt to maximize the worst-case sti ff ness of the structure. It is often that a structural optimization problem involving contact conditions is formulated as a mathematical programming problem with complementarity constraints (an MPCC problem). Since any feasible solution of an MPCC problem does not satisfy standard constraint qualifications, special treatment is required to solve an MPCC problem. In contrast, the formulation developed in this paper is free from complementarity constraints, and hence can be handled as a standard nonlinear programming problem. It is shown that this formulation is readily derived as a natural extension of the recently proposed optimal design problem formulation that does not consider uncertainty.","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115127413","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}

{"title":"A DES study of the flow around a full-scale train under crosswind condition","authors":"Taketo Ariki, Y. Shibasaki, Y. Kuya, M. Adachi, K. Sawada","doi":"10.1299/mel.22-00464","DOIUrl":"https://doi.org/10.1299/mel.22-00464","url":null,"abstract":"","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122881227","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}

{"title":"Quality improvement of deteriorated cutting fluid treated by atmospheric-pressure plasma jet and in-liquid plasma","authors":"J. Miyamoto, R. Tsuboi, Masashi Yoshida, K. Nambu","doi":"10.1299/mel.20-00100","DOIUrl":"https://doi.org/10.1299/mel.20-00100","url":null,"abstract":"Friction between a tool and chip, and the heat generated, often limit machining in metal cutting operations. Coolants and lubricants are used in great quantities to reduce friction at the cutting area. However, the cost of cutting fluids is increasing because of the increasingly stringent environmental standards for fluid handling and disposal, and these standards are likely to be further tightened in proposed national and international legislation (Weinert and Inasaki, 2004). Although dry and semi-dry machining is an attractive option, it is currently unavailable in many operations because cooling cannot be achieved (Tasdelen et al., 2008; Werda et al., 2016). Therefore, cutting fluids will continue to be required. As a fluid deteriorates, its cutting power decreases and the work environment becomes polluted. Techniques that extend the life of cutting fluids are therefore needed. One of the key causes of deterioration is decomposition due to bacterial growth (Rabenstein et al., 2009; Griffiths, 1978). Bacteria enter the fluid from both the air and the chip. Because preventing bacteria from contaminating the cutting fluid is difficult, chemical additives are widely used for bacterial control. The widespread use of oil additives has led to the emergence of resistant bacteria, and the additives change the characteristics of the cutting fluid. Therefore, we proposed a sterilization technique using plasma treatment under atmospheric pressure (Miyamoto et al., 2018). Moreover, we suggested that the molecular structure of the fluids was not affected by plasma jet treatment (Miyamoto et al., 2018). In our previous study, the number of bacterial colonies in fluid sterilized using atmospheric-pressure plasma was reduced by more than 90% compared with the number in an untreated fluid (Miyamoto et al., 2018). From this report, however, it is unclear whether the remaining bacteria and surface Junji MIYAMOTO*, Ryo TSUBOI*, Masashi YOSHIDA** and Koichiro NAMBU*** * Department of Mechanical Engineering, Daido University 10-3 Takiharu-cho, Minami-ku, Nagoya, Aichi 457-8530, Japan E-mail: j-miya@daido-it.ac.jp ** Department of Mechanical Systems Engineering, Daido University 10-3 Takiharu-cho, Minami-ku, Nagoya, Aichi 457-8530, Japan *** Toyota Technological Institute 2-12-1 Hisakata Tenpaku-ku, Nagoya, Japan","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128857423","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}

{"title":"Experimental determination of the emissivity of nuclear graphite at high temperature conditions","authors":"Peng Chai, Yang Wu, K. Okamoto","doi":"10.1299/mel.20-00204","DOIUrl":"https://doi.org/10.1299/mel.20-00204","url":null,"abstract":"increase and Lozier, 1958). Specifically, Seo (2009a; 2009b; 2011) measured the emissivity of several types of nuclear graphite in the temperature range from 100 ℃ to 500℃ and indicating a positive relationship between graphite emissivity and oxidation degree. Abstract In a High-Temperature Gas-cooled Reactor (HTGR), radiation is the dominant form of heat transfer due to the high temperature environment. Therefore, the emissivity of the core materials (mainly nuclear grade graphite) is important for reactor safety assessment. In this paper, the emissivity of nuclear grade graphite IG-110 was measured in the temperature range from 500 ˚C to 1000 ˚C by using an infrared thermometer. Besides, the impact of the graphite oxidation, which may take place in a postulated air ingress accident, was also evaluated. As a result, it was found that the emissivity of IG-110 grade graphite decreases slightly as the temperature increase. Moreover, a relatively high emissivity was detected in the pre-oxidized specimen. Based on the measurement data, two experimental correlations were suggested for the engineering applications. It could also be concluded that the commonly used value of the graphite emissivity (0.8), is conservative for engineering judgment.","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"201 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133810540","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}

{"title":"Volume conservation method for the three-dimensional front-tracking method","authors":"S. Takeuchi, G. Tryggvason","doi":"10.1299/mel.20-00216","DOIUrl":"https://doi.org/10.1299/mel.20-00216","url":null,"abstract":"A method to conserve the volume of dispersed components (e.g. bubbles and droplets) in a viscous fluid is proposed for the front-tracking method (Unverdi and Tryggvason, 1992; Tryggvason et al., 2001). The method adjusts the coordinates of each nodal points on the interface (or Lagrangian markers) along the velocity vector. A simplified algorithm determines the new position of the marker independently from those of the surrounding nodes, which allows the volume correction to be accomplished efficiently. The results show that the volume of a deformed fluid particle is kept constant within errors of O (10 − 7 ) ∼ O (10 − 6 ) . The effects of the time step size and the frequency of the volume correction are investigated. The method is applicable to enclosed structures of non-spherical geometry (e.g. oblate/prolate/spherical-cap fluid particles).","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133417956","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}

{"title":"Experimental study on the effects of fine bubbles on polydisperse submicron aerosol removal efficiency during pool scrubbing","authors":"Xingyong Zhang, K. Okamoto, N. Erkan, Takumi Saito","doi":"10.1299/mel.19-00655","DOIUrl":"https://doi.org/10.1299/mel.19-00655","url":null,"abstract":"Radioactive aerosols are strongly diffusive and migratory and thus have presented one of the greatest challenges during the decommissioning of the Fukushima Daiichi Nuclear Power Plant (NPP). Although cutting through debris underwater can suppress the generation of radioactive aerosols from pool scrubbing to some extent, the removal efficiency of bubble columns can be influenced by many factors. In this study, fine bubbles (microbubbles and nanobubbles) with large specific surface areas were introduced into a simple scrubber; nanobubbles, in particular, are known to have long residence times in water. The effects of fine bubbles on the aerosol removal efficiency during pool scrubbing were studied for TiO 2 (around 100 nm) and ZrO 2 (around 100 nm) aerosols. Due to the fact that TiO 2 (4.23g/cm 3 ) has similar density with CsOH (3.68g/cm 3 ) and CsI (4.51g/cm 3 ). On the other hand, ZrO 2 was found in the fuel debris (Zirconium-Water Reaction). To clarify the effects of fine bubbles, three kinds of water were prepared (i.e., distilled water, nanobubble water, and microbubble water). As a result, the removal efficiency of fine bubbles for TiO 2 aerosols decreased, while that observed for ZrO 2 aerosols improved in some cases. The improved removal efficiency achieved using fine bubbles may provide a new method for suppressing the generation of radioactive aerosols in the decommissioning of the Fukushima Daiichi NPP. the submicron radioactive aerosols due to pool scrubbing the removal efficiency of bubble columns by many In the of aerosol by described by Fuchs (1964) and Ghiaasiaan (1997), the internal circulation of gas inside a rising gas bubble is equivalent to Hill’s vortex and the absorption of aerosols at the interfaces of the rising bubbles can be described by inertial deposition, sedimentation, and diffusion. These three processes are related to particle size, bubble size, and the velocity at which bubbles rise. Many methods have been proposed to increase the amount of aerosols removed by the water phase, including air bubble subdividing devices (Cadavid-Rodriguez, 2014) and surfactants (Koch, 2012). Additionally, it has been shown that the strength of the internal circulation within bubbles is an important parameter affecting its particle removal rate. Slower internal circulation due to the presence of surfactants at the water–bubble interface will greatly reduce the particle removal rate (Friedlander, 2000). However, by adding surfactants, many microbubbles (MBs) can be generated at the nozzle inlet (Koch, 2012) and more particles can be removed from the resultant MBs due to their small size. Therefore, to achieve the highest removal efficiency with surfactants, the trade-off between internal circulation and bubble size is unavoidable.","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128769310","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}

{"title":"One-dimensional flow analysis of steady pressure field around a train running in a long tube with a constant width slit","authors":"M. Iida, K. Kikuchi","doi":"10.1299/MEL.21-00006","DOIUrl":"https://doi.org/10.1299/MEL.21-00006","url":null,"abstract":"A one-dimensional theoretical analysis is made of the pressure field around a train running in a long tube with a constant width slit, which is a simplified model of partially enclosed structures (or vented tubes) of railway, such as snow shelters or whole covered stations. It is shown from field measurement results in Shinkansen that the pressure field produced in such partially enclosed structures exhibits a pattern of ‘a combination of single sawtooth and its reverse’. The present analysis of a tube with a slit reproduces this unique pressure pattern and shows that one-dimensional pressure field ahead of the train nose and tail can be expressed by elementary functions. It also reveals that the magnitude of the pressure change around the tail can exceed that around the nose, which is also a unique feature that is di ff erent from the cases of open air spaces and fully enclosed spaces (i.e., tunnels).","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122334778","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}

{"title":"Prediction of stress concentration at fillets using a neural network for efficient finite element analysis","authors":"Taichiro Yamaguchi, H. Okuda","doi":"10.1299/mel.20-00318","DOIUrl":"https://doi.org/10.1299/mel.20-00318","url":null,"abstract":"In finite element analysis, small fillets make mesh generation difficult and accurate evaluation of stress concentration at fillets requires refined meshes. Simplified analysis is often performed using a corner model where the fillets are removed. In the analysis using a corner model, mesh division becomes easier and the number of elements is reduced, which shortens the calculation time. However, the stress concentrations cannot be evaluated, and stress singularities occur at corners. We have developed a method for predicting the stress at a fillet based on the simulation of a simplified corner model and the use of a neural network. We use the stress distribution at a corner as the neural network input such that the method can be applied to arbitrary object shapes, loading, and boundary conditions. We trained and validated the neural network using simple corner and fillet models. It was shown that stress distribution at a corner can express the difference in loading conditions. In addition, we found that the method can predict stress at fillets of models that were not used for the neural network training. These results show the possibility that the method enables efficient stress concentration evaluation in finite element analysis.","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129747119","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}

{"title":"Comparison of power density of transmission elements in hydraulic, pneumatic, and electric drive systems","authors":"T. Kazama","doi":"10.1299/mel.19-00139","DOIUrl":"https://doi.org/10.1299/mel.19-00139","url":null,"abstract":"This paper explores the transmittable power of power transmission elements in fluid power and electric drive systems. We consider a simple model for the piping in hydraulic and pneumatic systems that ignores the fittings and auxiliary equipment and the wiring in electric drive systems that ignores the terminals and auxiliary equipment. We analyze the data based on specifications of hoses for hydraulic systems, tubes for pneumatic systems, and cables for electric drive systems from the manufacturers’ catalogs. We survey the outer and inner diameters, mass per unit length, maximum working pressure, mean flow velocity, rated voltage, and rated current to estimate the maximum transmitted power and examine the relationship between the power and the size and weight and calculate the power density. The influences of mass of oil, return lines of hydraulic circuit, materials of pneumatic tubes, and number of cable cores are also discussed. In conclusion, the transmittable power of the elements of all systems can be approximated by a power function for the mass per unit length. The relation between the transmittable power and the mass for hoses, tubes, and wires is similar. The power density of hydraulic hoses and electrical cables is high; the power density of pneumatic tubes is low. Oil in the pipes and return lines of hydraulic systems is not","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129917395","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}