Computational Methods and Experimental Measurements XIX最新文献

{"title":"FUNDAMENTAL STUDY OF AN ADAPTIVE EVACUATION GUIDE SIGN BY USING A DISCRETE ELEMENT METHOD-BASED SIMULATION","authors":"H. Horii, Akihito Ito, N. Tsujiuchi, Takahiro Fukuda, Yusuke Kasahara","doi":"10.2495/CMEM190141","DOIUrl":"https://doi.org/10.2495/CMEM190141","url":null,"abstract":"In this study, an adaptive evacuation guide sign is proposed, and a fundamental evaluation is performed by using a discrete element method (DEM)-based simulation. When a disaster occurs in a large, closed space that has many emergency exits, such as a building or an underground area, having an evacuation route guide to an emergency exit that avoids intensive congestion of evacuees is important. The adaptive evacuation guide sign monitors the situations of the disaster and the evacuation which changes frequently and controls the direction of evacuation. A simulation model is constructed by using a DEM-based simulation which introduces pseudo-spring and pseudo-radius to interactions among discrete elements for representing evacuees’ behaviour. The pseudo-spring and the pseudo-radius are representing the personal space of evacuees and they affect interaction among evacuees during evacuation. At a fundamental evaluation, a limited area that has six emergency exits with three adaptive evacuation guide signs is modelled for evaluating efficiency of the guide sign.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116664330","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":"CORRECT SIZING OF REFLECTORS IN ULTRASONIC INSPECTION OF THE FORGING TITANIUM ALLOY","authors":"Theodoră Tranc, I. Radu","doi":"10.2495/CMEM190121","DOIUrl":"https://doi.org/10.2495/CMEM190121","url":null,"abstract":"Commercial Ti-6Al-4V forgings are widely used in the rotating components of aircraft engines. The failure of such parts can be quite catastrophic because of the large amount of kinetic energy. To ensure the safety and longer lifetime of these critical parts working in the hostile environments of high temperature and high stress, the need to detect smaller defects becomes more and more important. Ultrasonic inspection is one of the non-destructive evaluation (NDE) methods widely used by the titanium forging’s manufacturers because of its ability to penetrate the interior of a component. Over the last decade, sizing methods were established like DGS (Distance Gain Size) or DAC (Distance Amplitude Correction) for defects smaller than the beam profile. Those methods utilize the echo amplitude and provide results which are proportional to the defect area. In this article, the correct sizing of small defects below one wavelength is investigated. By properly choosing the simulation method, it is ensured that all physical wave modes are included in the simulation and that the discretization error is negligible. A good correspondence between the simulation and classical defect sizing for defects larger than one wavelength is found. In the region between one quarter of a wavelength and one wavelength resonance effects are found, which results in classical defect sizing methods giving conservative results. In the region below one quarter of a wavelength classical DGS and DAC sizing leads to under-sizing.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126430916","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":"MOLTEN STATE OF THERMOPLASTIC RESIN IN AN INJECTION MOULDING BARREL","authors":"So Shimokusuzono, Tatsuya Tanaka, M. Sasada, Y. Hirao, Kanta Hanafusa, A. Inoue","doi":"10.2495/CMEM190051","DOIUrl":"https://doi.org/10.2495/CMEM190051","url":null,"abstract":"In recent years, polymer products have required superior mechanical properties, a particular strength and dimensional accuracy. One of the most popular moulding methods for polymer materials is injection moulding. Compared to other moulding methods, injection moulding is better at making complicated shapes quicker; however, injection moulding suffers from many kinds of moulding faults. Various solutions to reduce the number of faults on a production line have been developed as a result of many years of studies. However, to further decrease the number of faults, researchers need to focus on the basic state of the plasticized resin. In injection moulding, it is important to determine how uniformly a resin is melted because the uniformity of temperature is related to the characteristics of a product. Therefore, melting completion does not mean that resin is uniform. The uniformity of melting must be accurately determined to achieve high quality. First, this study uncovers some effects of screw behaviours on plasticization. The injection moulding machine performs the metering and injection processes with the screw in the barrel. In the metering process, the screw retreats to the metering stroke while maintaining back pressure. In the injection process, the screw advances to the tip of the nozzle. While the screw repeats these movements, the pellets are provided from the hopper to the moving screw. This method of adding the pellets creates differences in the distance that the resin must travel within the screw channel. The longest distance that the resin must travel during an injection cycle is equal to the metering stroke. The viscosity of the resin depends on the barrel temperature, although the viscosity is also influenced by other moulding conditions. An experiment is performed by changing the metering stroke and the barrel temperature. To understand the condition of the resin just before the injection, an original nozzle with a pressure sensor is produced. Thus, the injection pressure waveform can be recorded during each cycle. As changes in the waveform are reflected in the behaviour of the resin, a non-uniform temperature can be visually confirmed by a disturbance in the waveform.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"379 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115906878","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":"CFD ANALYSIS OF LOW FREQUENCY OSCILLATIONS IN NEWTONIAN AND NON-NEWTONIAN FLUIDS IN A VERTICAL PIPE","authors":"M. Amaratunga, H. A. Rabenjafimanantsoa, R. W. Time","doi":"10.2495/CMEM190041","DOIUrl":"https://doi.org/10.2495/CMEM190041","url":null,"abstract":"The effect of vertically imposed, low frequency oscillations on the rheology of shear-thinning nonNewtonian fluids are studied numerically by computational fluid dynamics (CFD). Both Newtonian (water) and inelastic time-independent fluids of power-law (Poly-Anionic Cellulose (PAC)) are used as test fluids. Unsteady state simulations were performed using ANSYS Fluent version 18.0 for a vertical 2-D pipe geometry (ID = 50 mm and H = 850 mm) and sinusoidal, vertical oscillations to the liquid body itself were imposed with a user-defined function (UDF). The multiphase volume of fluid (VOF) method with realizable k-ε method was used to impose the turbulence nature of the flow for the cases with water while the cases with non-Newtonian fluids were simulated under the laminar condition. Oscillations of different low frequency values (0.25–5 Hz) and different velocity amplitudes (0.1–0.3 m/s) were tested numerically. The dynamic variation of velocity and shear rate within the oscillated, bulk liquid medium is demonstrated. The flow inside the vertical pipe acts plug like at higher frequencies for both Newtonian and non-Newtonian fluids. The air–liquid interface becomes unstable with small disruptive peaks for the cases with water at higher velocity amplitudes while that is very calm for the laminar cases with non-Newtonian fluids. The achieved velocity gradients and the resultant shear rate variation are low with the increased PAC concentration due to the viscous resistance. However, the instantaneous velocity profiles display a progressively more complex structure with increased frequency and velocity amplitude, revealing the presence of alternating upward/downward motion. These alternating velocity profiles confirm the varying shear field present within a drilling pipe at different frequencies and velocity amplitudes while the variation of the shear field is more dependent on the velocity amplitude.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132446672","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":"ANALYSIS OF JAPANESE FOLDING FAN’S CHARACTERISTIC STRUCTURE AND TRADITIONAL TECHNICAL SKILL","authors":"Fujiko Abe, Y. Ohbuchi, T. Katayama, H. Sakamoto","doi":"10.2495/CMEM190091","DOIUrl":"https://doi.org/10.2495/CMEM190091","url":null,"abstract":"Japanese folding fans were born during the Heian Period (794–1185) and have been used in every situation. Many Japanese fans are used widely at present as a portable fan, a tool of Japanese dance and tea ceremony. The making of folding fans in Japan has a history of 1,000 years or more and the production technology of the Japanese fan has been followed up until now. This research has aimed to clarify the characteristics of the traditional Japanese fan through the material of fan components, the fan-making process and the traditional production skill of a Japanese fan.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129258738","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 DOUBLE ACTIVE CONTROL SYSTEM DESIGN FOR DISTURBANCE REJECTION","authors":"Soumayya Chakir, V. T. Nguyen, Tae-Wan Kim, Dong-Hun Lee, J. Suh, Young-Bok Kim","doi":"10.2495/CMEM190081","DOIUrl":"https://doi.org/10.2495/CMEM190081","url":null,"abstract":"This paper introduces a new disturbance decoupling and rejection method based on robust control framework for a robot system with multiple arms. While in action, the movement of one individual arm of the robot system affects the motion of the other joint, which brings the control performance down. In order to compensate and keep the desirable control performance, the authors designed a double active control system which can effectively reject the direct mutual disturbances. The designed control system consists of two controllers, the first one is an inner loop controller and works as a disturbance observer that attenuates the disturbances. The second one, on the other hand, is an outer loop controller, which was designed based on H∞ control theory to maintain the system stability and a robust control performance under the uncertainty. The combined control system is applied, simulation and experimental results show that the proposed control system effectively suppress the mutual disturbances, and an enhanced tracking performance is obtained.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"119 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133969753","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":"3D MODELLING OF DUNE ECOSYSTEMS USING PHOTOGRAMMETRY FROM REMOTELY PILOTED AIR SYSTEMS SURVEYS","authors":"J. Pagán, I. López, L. Bañón, L. Aragonés","doi":"10.2495/CMEM190161","DOIUrl":"https://doi.org/10.2495/CMEM190161","url":null,"abstract":"Dune ecosystems play a key role in coastal dynamics, where a constant exchange of sediments between the sand dune and the beach exists. Thus, it is essential to measure with high precision its movements and monitor its evolution. Classical topographical surveys – even those based on real-time kinematic GPS surveys – are suitable for obtaining profiles with high accuracy, but their cost, in terms of time and personnel, make them inappropriate for large areas. Moreover, these techniques do not precisely measure volumetric changes in high-variable environments such as sand dunes. LiDAR is an active remote sensing method that reflects laser pulses off the land and records topographic positions, but LiDAR scanners are still an expensive and evolving technology. The use of Remotely Piloted Air Systems (RPAS) aims to solve this problem. RPAS map sand dunes using photogrammetric methods, such as Structure-from-Motion (SfM), to produce three-dimensional models from two-dimensional images. This methodology has the advantage of needing only a digital camera and is, therefore, cost effective. The objective of this study is to demonstrate the use of RPAS to map and model the sand dunes of Guardamar del Segura (Spain). The survey covered an extension of 226,000 m2. The results allow us to obtain a point cloud with a density of 30 points per sq m. A 3D digital elevation model of the dune has been created from the dense point cloud, with a vertical accuracy of 0.2 m Root Mean Square Error. An orthophoto was also created with a spatial resolution of 5 cm. The main conclusion is that the use of RPAS and SfM is an adequate technique to periodically monitor dune ecosystems with high accuracy and cost savings.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125044900","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":"NUMERICAL MODELING OF HIGH-VELOCITY, PROJECTILE PENETRATING CONCRETE BLOCKS REINFORCED BY TEFLON SHEETS","authors":"Aya E. Elhozayen, Mohamed Y. Lassi, W. Attia","doi":"10.2495/CMEM190021","DOIUrl":"https://doi.org/10.2495/CMEM190021","url":null,"abstract":"Recently, the concern about protecting people and structures has increased due to the increasing number of terrorist attacks. This paper presents a numerical simulation of plain concrete blocks with an unconfined compressive strength of 35 MPA, reinforced by Teflon sheets and subjected to ballistic impact by a high-velocity rigid projectile (960 m/s). The reinforcement sheets are modeled with different thicknesses and located at different depths from the face of the concrete target. The Teflon material was chosen due to its high impact strength over a wide range of temperatures. A validation model was conducted and results showed a good agreement with previous experimental results. The investigation presents the development of a finite element accurate model using AUTODYN 3D. The Lagrangian formulation numerical technique is used to model both the projectile and the concrete target. The main findings showed an enhancement in the penetration resistance of concrete target when reinforced by Teflon sheets compared to the concrete resistance without reinforcement, where the projectile depth of penetration was reduced by 64.8% and the full damage depth of the concrete target was also reduced by 58%, which demonstrates the great performance of the chosen reinforcement in the shock wave propagation.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124199130","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":"NON-LINEAR NUMERICAL MODELS FOR PREDICTING THE BOND STRENGTH OF FIBRE-REINFORCED CONCRETE AT HIGH TEMPERATURES","authors":"F. B. Varona, Y. Villacampa, F. J. Navarro-González, D. Bru, F. Baeza","doi":"10.2495/CMEM190191","DOIUrl":"https://doi.org/10.2495/CMEM190191","url":null,"abstract":"The authors want to acknowledge Generalitat Valenciana, which has made possible this piece of research through the grant GV/2018/015.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129424355","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":"AUTOMATIC DETECTION OF LOITERING BEHAVIOUR USING SPATIOTEMPORAL IMAGE PROCESSING","authors":"Yuta Ebihara, T. Katori, T. Izumi","doi":"10.2495/CMEM190131","DOIUrl":"https://doi.org/10.2495/CMEM190131","url":null,"abstract":"In this paper, the authors propose a method for detecting loitering behaviour automatically from security camera images acquired in a corridor or passage, and the authors examine the performance of the proposed method. Image sensors (security cameras) are widely used for crime prevention. In this study, for educational settings, the authors developed a system for automatically detecting loitering behaviour where a student is worried about whether he or she is permitted to enter a laboratory on his/her first visit. Using the results, staff in the laboratory can approach them and appropriately guide the student during his or her visit. The purpose of this study is to detect loitering behaviour including fuzzy actions. Detecting loitering behaviour involves the ethical issue of ensuring that the captured images do not infringe an individual’s privacy. In addition, there are a number of technical problems: What is a unique characteristic value indicating the target behaviour?; the method should not require much computational power; and it should be possible to explain the reason for the judgment result. In this study, to ensure privacy, the authors avoid using original images, for example, images in which the face or body of an individual can be recognized, and instead the authors use spatiotemporal images. General image processing is highly complex and requires computers using high-performance CPUs and a lot of memory. However, usual video capturing and behaviour recognition are expected to involve lower complexity. Spatiotemporal image processing can solve the technical problems mentioned above, for example, decreasing the computational complexity and maintaining high computational performance. In addition, as a measurement characteristic value, the authors adopt a simple staying time only, and the authors classify the behaviour into only two categories: “loitering behaviour” or “not loitering”.","PeriodicalId":368047,"journal":{"name":"Computational Methods and Experimental Measurements XIX","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126411698","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}