| 61. |
- Camuz, Soner, 1988, et al.
(författare)
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Contact Variation Optimization for Surface-to-Surface Contacts
- 2017
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Ingår i: Proceedings of International Mechanical Engineering Congress & Exposition. ; 2
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Konferensbidrag (refereegranskat)abstract
- Locating schemes, used to position parts during manufacturing, are usually designed in such a way that the response from the system is minimized. This implies that the position of the fasteners and/or welds are known in an assembly. Today there exist numerous of methods aiming to find an optimal set of locating points to increase the stability of an assembly, for both rigid and compliant parts. However, various industrial applications use surface-to-surface contacts to constrain certain degrees of freedom. This can lead to designs sensitive to geometric and load variations. As the complexity of the surfaces increases, difficulties of allocating geometric tolerances arise. An approach to control this is to keep the contact locations statistically stable. In this paper a methodology is presented where the First-Order reliability Method (FORM) is applied for numerical data, retrieved through Finite Element Analysis (FEA), to ensure that statistically stable contact location are achieved for two bodies with surface-to-suface contact. The FEA data represents how much of the total stress that lies within a given area, sW. The data is continuous and therefore it is assumed that the gradient can be calculated numerically with small steps. The objective function is to maximize sW for n variables. The data set is simulated through Finite Element Analysis using the commercial software Ansys and the results is illustrated on a case study from the machining industry.
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| 62. |
- Camuz, Soner, 1988, et al.
(författare)
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Reliability based design optimization of surface-to-surface contact for cutting tool interface designs
- 2019
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Ingår i: Journal of manufacturing science and engineering. - ASME : ASME International. - 1087-1357 .- 1528-8935.
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Tidskriftsartikel (refereegranskat)abstract
- In recent year, cutting tool manufacturers are moving towards improving the robustness of the positioning of an insert in the tool body interface. Increasing the robustness of the interface involves designs with both chamfered and serrated surfaces. These designs have a tendency to over-determine the positioning and cause instabilities in the interface. Cutting forces generated from the machining process will also plastically deform the interface, consequently, altering the positioning of the insert. Current methodologies within positioning and variation simulation use point-based contacts and assume linear material behaviour. In this article, a first order reliability-based design optimization framework that allows robust positioning of surface-to-surface-based contacts is presented. Results show that the contact variation over the interface can be limited to pre-defined contact zones, consequently allowing successful positioning of inserts in early design phases of cutting tool designs.
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| 63. |
- Candefjord, Stefan, 1981, et al.
(författare)
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On Scene Injury Severity Prediction (OSISP) machine learning algorithms for motor vehicle crash occupants in US
- 2021
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Ingår i: Journal of Transport and Health. - : Elsevier BV. - 2214-1405. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- A significant proportion of motor vehicle crash fatalities are potentially preventable with improved acute care. By increasing the accuracy of triage more victims could be transported directly to the best suited care facility and be provided optimal care. We hypothesize that On Scene Injury Severity Prediction (OSISP) algorithms, developed utilizing machine learning methods, have potential to improve triage by complementing the field triage protocol. In this study, the accuracy of OSISP algorithms based on the “National Automotive Sampling System - Crashworthiness Data System” (NASS-CDS) of crashes involving adult occupants for calendar years 2010–2015 was evaluated. Severe injury was the dependent variable, defined as Injury Severity Score (ISS) > 15. The dataset contained 37873 subjects, whereof 21589 included injury data and were further analyzed. Selection of model predictors was based on potential for injury severity prediction and perceived feasibility of assessment by first responders. We excluded vehicle telemetry data due to the limited availability of these systems in the contemporary vehicle fleet, and because this data is not yet being utilized in prehospital care. The machine learning algorithms Logistic Regression, Ridge Regression, Bernoulli Naïve Bayes, Stochastic Gradient Descent and Artificial Neural Networks were evaluated. Best performance with small margin was achieved with Logistic Regression, achieving area under the receiver operator characteristic curve (AUC) of 0.86 (95% confidence interval 0.82–0.90), as estimated by 10-fold stratified cross-validation. Ejection, Entrapment, Belt use, Airbag deployment and Crash type were good predictors. Using only a subset of the 5–7 best predictors approached the prediction accuracy achieved when using the full set (14 predictors). A simplified benefit analysis indicated that nationwide implementation of OSISP in the US could bring improved care for 3100 severely injured patients, and reduce unnecessary use of trauma center resources for 94000 non-severely injured patients, every year.
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| 64. |
- Candefjord, Stefan, 1981, et al.
(författare)
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Using Smartphones to Monitor Cycling and Automatically Detect Accidents - Towards eCall Functionality for Cyclists
- 2014
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Ingår i: Proceedings, International Cycling Safety Conference 2014. ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- Automatic crash notification to the nearest emergency center in case of a traffic accident will through the EU initiative eCall improve the safety for cars on European roads. eCall function- ality could also increase the safety for vulnerable road users such as cyclists, but there is no technical implementation agreed upon for this purpose. We propose to use smartphones due to their widespread availability and no need for extra hardware. Today’s high-end smartphones are equipped with both GPS functionality and movement sensors. The aims of this study were to explore if smartphones can be used to collect cycling data of sufficient quality and to design and evaluate a crash detection algorithm (CDA) for cycling accidents. A Google Nexus 4 smartphone was chosen for the study. This device is equipped with a combined accelerometer and gyroscope chip. Over five hours of “normal” cycling data, i.e. without accidents/incidents, was collected. Six crash tests were performed using a simplified crash test dummy. In order to achieve a realistic user scenario the smartphone was allowed to be easily carried as in everyday use, i.e. the users were not required to fix it to the body. We used the total acceleration based on the sum of square of each direction to obtain a measure independent on smartphone orientation. For normal cycling this measure was found to momentarily be as high as 50 ms−2. High levels were often due to handling of the smartphone. This prompted that an acceleration threshold alone is not sufficient for an accurate CDA. A marked rotation during a short time interval was found to be an important predictor for crashes. An accurate CDA was designed based on a combination of sensor data such as acceleration and rotation. The CDA detected all crashes and was subsequently evaluated in several hours of normal cycling without any false positive alarms.
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| 65. |
- Chandolias, Konstantinos, 1985-, et al.
(författare)
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Effects of Heavy Metals and pH on the Conversion of Biomass to Hydrogen via Syngas Fermentation
- 2018
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Ingår i: BioResources. - : BioResources. - 1930-2126 .- 1930-2126. ; 13:2, s. 4455-4469
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Tidskriftsartikel (refereegranskat)abstract
- The effects of three heavy metals on hydrogen production via syngas fermentation were investigated within a metal concentration range of 0 to 1.5 mg Cu/L, 0 to 9 mg Zn/L, 0 to 42 mg Mn/L, in media with initial pH of 5, 6, and 7, at 55 degrees C. The results showed that at lower metal concentration, pH 6 was optimum while at higher metal concentrations, pH 5 stimulated the process. More specifically, the highest hydrogen production activity recorded was 155% +/- 12% at a metal concentration of 0.04 mg Cu/L, 0.25 mg Zn/L, and 1.06 mg Mn/L and an initial medium pH of 6. At higher metal concentration (0.625 mg Cu/L, 3.75 mg Zn/L, and 17.5 mg Mn/L), only pH 5 was stimulating for the cells. The results showed that the addition of heavy metals, contained in gasification-derived ash, can improve the production rate and yield of fermentative hydrogen. This could lead to lower costs in gasification process and fermentative hydrogen production and less demand for syngas cleaning before syngas fermentation.
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| 66. |
- Chandolias, Konstantinos, et al.
(författare)
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Protective effect of a reverse membrane bioreactor against toluene and naphthalene in anaerobic digestion
- 2022
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Ingår i: Biotechnology and Applied Biochemistry. - : Wiley. - 1470-8744 .- 0885-4513. ; 69:3, s. 1267 -1274
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Tidskriftsartikel (refereegranskat)abstract
- Raw syngas contains tar contaminants including toluene and naphthalene, which inhibit its conversion to methane. Cell encasement in a hydrophilic reverse membrane bioreactor (RMBR) could protect the cells from hydrophobic contaminants. This study aimed to investigate the inhibition of toluene and naphthalene and the effect of using RMBR. In this work, toluene and naphthalene were added at concentrations of 0.5–1.0 and 0.1–0.2 g/L in batch operation. In continuous operation, concentration of 0–6.44 g/L for toluene and 0–1.28 g/L for naphthalene were studied. The results showed that no inhibition was observed in batch operation for toluene and naphthalene at concentrations up to 1 and 0.2 g/L, respectively. In continuous operation of free cell bioreactors (FCBRs), inhibition of toluene and naphthalene started at 2.05 and 0.63 g/L, respectively. When they were present simultaneously, inhibition of toluene and naphthalene occurred at concentrations of 3.14 and 0.63 g/L, respectively. In continuous RMBRs, no inhibition for toluene and less inhibition for naphthalene were observed, resulting in higher methane production from RMBR than that of FCBR. These results indicated that RMBR system gave a better protection effect against inhibitors compared with FCBR.
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| 67. |
- Christia, Abdi, 1991, et al.
(författare)
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Ethanol production from alkali-pretreated oil palm empty fruit bunch by simultaneous saccharification and fermentation with mucor indicus
- 2016
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Ingår i: International Journal of Green Energy. - : Informa UK Limited. - 1543-5075 .- 1543-5083. ; 13:6, s. 566-572
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Tidskriftsartikel (refereegranskat)abstract
- Oil palm empty fruit bunch (OPEFB) is a potential raw material for production of lignocellulosic bioethanol. The OPEFB was pretreated with 8% sodium hydroxide (NaOH) solution at 100°C for 10 to 90 min. Enzymatic digestion was carried out using cellulase and β-glucosidase at 45°C for 24 h. It was then inoculated with Mucor indicus spores suspension and fermented under anaerobic conditions at 37°C for 96 h. Sodium hydroxide pretreatment effectively removed 51–57% of lignin in the OPEFB and also its hemicellulose (40–84%). The highest glucan digestibility (0.75 g/g theoretical glucose) was achieved in 40-min NaOH pretreatment. Fermentation by M. indicus resulted in 68.4% of the theoretical ethanol yield, while glycerol (16.2–83.2 mg/g), succinic acid (0–0.4 mg/g), and acetic acid (0–0.9 mg/g) were its by-products. According to these results, 11.75 million tons of dry OPEFB in Indonesia can be converted into 1.5 billion liters of ethanol per year.
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| 68. |
- Christie, Michael, 1946, et al.
(författare)
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Barriers to innovation in online pedagogy
- 2009
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Ingår i: European Journal of Engineering Education. - : Taylor & Francis Ltd.. - 0304-3797 .- 1469-5898.
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Konferensbidrag (refereegranskat)abstract
- In this article, the authors report on a study that was carried out at the University College of Boras. Teachers using an online learning platform (WebCT) were surveyed to see to what extent they made use of the various features available to them on the learning platform. The extent to which teachers employed all the features was low. The article provides comparative details about the use of the various features (chat, discussion forums, assessment etc) and analyses reasons for their underutilisation. This case study is used to make more general points about pedagogy of online learning and discusses the need for greater cooperation between all the stakeholders involved in putting courses online. It can be counter productive for a university to simply impose a learning management system upon its teaching staff and decree that they put their courses online. If a university is concerned with quality and innovation in the education it offers its students, then a great deal of groundwork needs to be done if teachers and students are going to get the most out of a move to blended or online learning. This article offers a number of recommendations for ensuring that teachers embrace rather than resist a move to innovative and quality assured online education. (Contains 1 note and 2 figures.)
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| 69. |
- Ciszuk, Martin
(författare)
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Silk Weaving in Sweden During the 19th Century : Textiles and texts - An evaluation of the source material
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Silk-weaving in Sweden during the 19th century. Textiles and texts - An evaluation of the source material. With the rich material available, 19th century silk-weaving invites to studies on industrialisation processes. The purpose of this licentiate thesis is to present and discuss an empirical material regarding silk production in Sweden in the 19th century, to examine the possibilities and problems of different kinds of materials when used as source materials, and to describe how this material can be systematized and analysed in relation to the perspective of a textile scientific interpretation. The introductory sections of the thesis provide a background to textile research and the subject of textile science. This is followed by an overview of previous research on silk-weaving in Sweden and a historical overview of silk-weaving in Sweden, the Jacquard machine, and the K.A. Almgren Sidenväveri, where large parts of the source material have been preserved. After these overviews, the research material is described and systematized: first the main materials, textiles, machines and other objects, and then the various written sources. By way of conclusion, the empirical material is summarized in a critical discussion where the various groups of materials are evaluated in comparison to one another. A discussion on theory and methodology regarding objects as sources and the use of experience-based knowledge in academic research is developed in connection to the critical discussion. Finally, the potential of the material is demonstrated through a textile example. The presentation is an introduction to the cultural-historical analysis that will follow in the PhD thesis. Here, the empirical material will be analysed through the use of knowledge in handicrafts, which may create new dimensions of silk production in Sweden and the complexity of the industrialisation process.
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| 70. |
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