| 52781. |
- Lytsy, Birgitta, 1968-, et al.
(författare)
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Source strength as a measurement to define the ability of clean air suits to reduce airborne contamination in operating rooms
- 2022
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Ingår i: Journal of Hospital Infection. - : Elsevier BV. - 0195-6701 .- 1532-2939. ; 119, s. 9-15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Surgical site infections after total hip and knee replacement are linked to the quality of the operating room (OR) air. Applying tight occlusive clothing, effective ventilation and correct working methods are key concepts to obtain low bacterial concentrations in the OR air. The dry penetration test referred to in European standard EN 13795-2:2019 is a screening method for materials used in surgical clothing. Source strength, defined as the dispersal of bacteria-carrying particles from persons during activity, is a functional test of clothing systems and has been calculated in a dispersal chamber and in ORs. Results from both tests can be used when comparing surgical clothing systems. Aim: This study relates results of dry penetration tests to source strength values for five surgical clothing systems available on the Swedish market. Methods: Experimental data are reported on the function of these products, expressed as source strength calculated from results in a dispersal chamber and in ORs during orthopaedic operations. Findings: All materials tested with dry penetration ≤50 colony-forming units (cfu) had source strength values <3 cfu/s for one person in the dispersal chamber, whereas the material of one product when laundered >50 times had source strength in the dispersal chamber of up to 8 cfu/s. Conclusion: The dry penetration test could predict the performance of clean air suits of the same design, but more studies are needed to obtain a more valid correlation. Requirements of source strength should be included in standards.
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| 52782. |
- Lyu, Cheng, et al.
(författare)
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Personalized Modeling of Travel Behaviors and Traffic Dynamics
- 2022
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Ingår i: Journal of Transportation Engineering Part A: Systems. - 2473-2893 .- 2473-2907. ; 148:10
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Tidskriftsartikel (refereegranskat)abstract
- Emerging mobile Internet applications have become valuable data sources for fine-grained transportation analysis, which allows the introduction of the concept of Personalization in both microscopic and macroscopic modeling of travel behaviors and traffic dynamics. Inspired by personalized recommendation systems, the personalized transportation models emphasize the importance of individual and local information. Two representative cases are presented in this study and two architectures, namely the travel behavior modeling architecture and the geoinformation modeling architecture, are proposed to address the problems of bike-sharing destination prediction and ensemble of ride-hailing demand predictors, respectively. Their performance has been verified by two case studies using the Mobike bike-sharing data and the DiDi ride-hailing demand data.
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| 52783. |
- Lyu, Haozhou, et al.
(författare)
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Developer Views on Software Carbon Footprint and Its Potential for Automated Reduction
- 2023
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Ingår i: Search-Based Software Engineering. SSBSE 2023. Lecture Notes in Computer Science, vol 14415.
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Konferensbidrag (refereegranskat)abstract
- Reducing software carbon footprint could contribute to efforts to avert climate change. Past research indicates that developers lack knowledge on energy consumption and carbon footprint, and existing reduction guidelines are difficult to apply. Therefore, we propose that automated reduction methods should be explored, e.g., through genetic improvement. However, such tools must be voluntarily adopted and regularly used to have an impact. In this study, we have conducted interviews and a survey (a) to explore developers’ existing opinions, knowledge, and practices with regard to carbon footprint and energy consumption, and (b), to identify the requirements that automated reduction tools must meet to ensure adoption. Our findings offer a foundation for future research on practices, guidelines, and automated tools that address software carbon footprint.
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| 52784. |
- Lyu, Haozhou, et al.
(författare)
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Exploring Genetic Improvement of the Carbon Footprint of Web Pages
- 2024
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Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - 1611-3349 .- 0302-9743. ; 14415 LNCS, s. 67-83
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Konferensbidrag (refereegranskat)abstract
- In this study, we explore automated reduction of the carbon footprint of web pages through genetic improvement, a process that produces alternative versions of a program by applying program transformations intended to optimize qualities of interest. We introduce a prototype tool that imposes transformations to HTML, CSS, and JavaScript code, as well as image resources, that minimize the quantity of data transferred and memory usage while also minimizing impact to the user experience (measured through loading time and number of changes imposed).
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| 52785. |
- Lyu, Sai, et al.
(författare)
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Oxygen Evolution at the BiVO4-Water Interface: Mechanism of the Water Dehydrogenation Reaction
- 2022
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 12:19, s. 11734-11742
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Tidskriftsartikel (refereegranskat)abstract
- We study the water dehydrogenation reaction at the BiVO4(010)-water interface by combining nudged-elastic-band calculations and electronic structure calculations at the hybrid functional level. We investigate the pathway and the kinetic barrier for the adiabatic reaction going from the hole polaron localized in BiVO4 to the dehydrogenation of the adsorbed water molecule at the interface. The reaction is found to involve the H2O center dot+ radical cation as an intermediate, to have a kinetic barrier of 0.7 eV, and to be initiated by the electron transfer. The calculated kinetic barrier is in good agreement with experiment and is consistent with the slow hole transfer kinetics observed at the surface of BiVO4. To characterize the structural changes occurring during this process, we analyze the O-H distances for three relevant water molecules. We also examine the Wannier functions around the O atom of the adsorbate involved in the reaction to reveal the changes in the electronic structure during the hole hopping. The projected density of states of the lowest unoccupied molecular orbitals allows us to identify the atomic orbitals that are primarily involved in the reaction. We expect that the proposed reaction mechanism generally holds when the surface coverage is dominated by molecularly adsorbed water.
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| 52786. |
- Lähteenmäki-Uutela, Anu, et al.
(författare)
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What explains SECA compliance: rational calculation or moral judgment?
- 2019
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Ingår i: WMU Journal of Maritime Affairs. - : Springer Science and Business Media LLC. - 1651-436X .- 1654-1642. ; 18:1, s. 61-78
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Tidskriftsartikel (refereegranskat)abstract
- We explain the Sulphur Emission Control Area (SECA) compliance through analyzing both rational and moral factors for compliance motivation. According to preliminary analysis based on samples and measurements, the compliance rate for SECA is rather good and air quality has improved significantly. As costs of compliance are rather high and penalties for non-compliance rather low for regulation targets, moral motivation factors must be relevant for compliance. Maintaining good relationships with control authorities and peers requires shipowners to comply with the rules for practical and moral legitimacy. Our interviews with Danish, Finnish and Estonian shipowners confirmed that most of them follow the law simply because it is the law, this applying both to current Baltic Sea SECA rules and the future global sulphur emission rules. Obeying environmental law thus has a taken-for-granted status among shipping companies. Almost half of the companies specifically mentioned they follow the SECA rules because they want to take care of the environment, thus having internalized the regulatory content. Some companies see global compliance to depend on efficient controls.
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| 52787. |
- Lämkull, Dan, 1966, et al.
(författare)
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A comparative study of digital human modelling simulation results and their outcomes in reality : A case study within manual assembly of automobiles
- 2009
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier. - 0169-8141 .- 1872-8219. ; 39:2, s. 428-441
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to examine to what extent ergonomics simulations of manual assembly tasks correctly predict the real outcomes in the plants and if recommended measures originating from ergonomics simulations are taken into consideration. 155 ergonomics simulation cases were used in the study and all cases were performed by nine simulation engineers at Volvo Car Corporation in Gothenburg. The evaluations of the ergonomics conditions of the simulated tasks were done by six professional ergonomists working at Volvo Car Corporation in Gothenburg. The results show that digital human modelling tools (DHM-tools) are useful for the purpose of providing designs for standing and unconstrained working postures. Furthermore, the design of various auxiliary devices and their needed space for movements is a prevalent use of DHM-tools. However, the study also identifies areas that require additional development in order to further improve the digital human modelling tools' possibility to correctly predict a work task's real outcome, i.e. hand access, push pressure and pull forces, leaning and balance behaviour and field of vision. Moreover, a better feedback of product and process changes and a more careful order description of simulation cases to the simulation engineers would lead to improved simulation results in current and future projects.Relevance to industry: DHM-tools are increasingly the major means used to perform ergonomics analyses of manual assembly tasks in the automotive industry, but there is still a need for improvements of the tools. It is of great importance to disseminate end users' experiences of the use of different DHM-tools so these can be developed and applied in a more efficient way.
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| 52788. |
- Lämkull, Dan, 1966
(författare)
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Computer Manikins in Evaluation of Manual Assembly Tasks
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Time to market is a critical success factor in todays business environment. The challange is to reduce the development cycle without sacrificing the performance and quality of products and production systems. With the short-lived products of todays competetive global markets most of the engineering has to be done before the start of the production and simultaneous with product development simultaneous engineering.Any use of computer software to solve engineering problems is called computer-aided engineering, and has become one of the most important tools for simultaneous engineering. Fast, high quality computer graphics now allow us to render lifelike images of people performing a multitude of tasks within various computer aided engineering programs. Thus it now is possible to position and move manikins to predict the performance capabilities of designated groups of people within a computer rendered environment. Digital human modelling tools have been introduced in industry to facilitate a faster and more cost efficient design process. Most of the tool users are in the fields of automotive and aerospace engineering. The tools are applied in the design, modification, visualization and analysis of human workplace layouts and/or product interactions.Focus of research within ergonomics simulation has primarily been related to improve the simulation tools with more enhanced functionalities resulting in better and more accurate posture and motion algorithms and biomechanical models. Considerably less research has been conducted to investigate the needs of organizations and end users and their experiences of using the digital human modelling tools.The aim of the research in this thesis is to enlighten the importance of some of the features which can make the manufacturing simulation results more realistic and increase their credibility. Two studies are presented. The aim of the first study was to investigate whether different appearances of manikins in detail levels and genders influence the observers ergonomics posture evaluations, as well as to see if the evaluations differ between the three working disciplines: manufacturing managers, simulation engineers and ergonomists. The primary aspect addressed by the second study was whether repeated simulation results achieved by using a posture prediction tool were more uniform than results achieved by manual manipulating of all body angles. The uniformity was compared both among users and within users. Another aspect addressed was time needed to carry out a simulation case when using a posture prediction tool or not.Results from the first study show that manufacturing managers and simulation engineers were influenced by the appearance whereas ergonomists showed no significance in being influenced by the appearance of the manikins. Moreover, only the ergonomists could distinguish between the different workpostures used in the study. These were different in workload and classified according to the OWAS-system. Results from the second study show that the use of a posture prediction tool, in such complex tasks as the study included, neither reduced time needed to fulfill a simulation, nor differences within or among simulation engineers, at least not significantly. Differences in simulation results often originate from the different assumptions the simulation engineers have of the task when positioning the manikins. The differences could be minimized by a more careful order description and by such activities as simulation engineering days at assembly plants and by bringing the people working with human simulation tools together in the organization.
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| 52789. |
- Lämkull, Dan, 1966
(författare)
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Computer Manikins in Evaluation of Manual Assembly Tasks
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Digital human modelling (DHM) tools have been introduced in industry to facilitate a faster and more cost efficient design process. The research in this thesis is directed towards the DHM-tool-users’ needs and the objective is to identify difficulties and shortcomings, and identify requirements for improving the output of DHM-simulations.The research is directed towards both the tool functions and the processes related to the use of the tools. Five studies are presented in the thesis.In the first study three examples of the development of DHM-based company-specific ergonomics evaluation methods and work processes are portrayed. These illustrate the use of DHM-tools for performing static work and occupant packaging analyses, as well as customizing activities made for the implementation of the tools in companies’ work processes. This is followed by a discussion of future needs of DHM-tools including the call for ergonomics methods for evaluating full work cycles.The second study shows that DHM-tools correctly predict ergonomics issues for standing and unconstrained working postures. However, for more complex and constrained working postures the tools must be used with caution to prevent an unlikely working posture from being the result/outcome of an ergonomics simulation. The third study confirms that posture differences are found in simulation results between users who carry out identical simulation cases. However, humans are different and tasks are carried out differently. Thus, simulation engineers should preferably simulate and visualize a number of different strategies when analysing work tasks. The fourth study illustrates how the appearance of a manikin used when showing and visually evaluating ergonomics conditions makes a difference. Knowledge in ergonomics and/or experience of making visual ergonomics posture evaluations decreases the appearance modes’ influences on the observers. The fifth study exemplifies a method where time sensitive wrist exposure data are extracted from a manikin’s wrist movements. The results show that the exemplified method makes it easy to compare simulations with data from avaliable field studies. However, to be able to use the data to predict prevalence for work-related musculoskeletal disorders additional research is needed to understand the different exposure-dimensions’ (position, velocity, rest) importance as epidemiological risk factors.
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| 52790. |
- Lämkull, Dan, 1966, et al.
(författare)
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Consistency in figure posturing results within and between simulation engineers
- 2006
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an effort to compare figure posturing results within and between simulation engineers. The simulation engineers simulated four manual tasks. Alternately they used a posture prediction tool, and alternately they were only allowed to apply manual adjustments of the body angles. The simulation engineers repeated each task six times and always with at least six days between each occasion, to minimize the subject's rememberance of how she/he carried out the cases. Results show that the use of a posture prediction tool, in such complex tasks as the study includes, neither reduces needed time to fulfill a simulation, nor differences within or between simulation engineers. Differences in simulation results often originate from the different assumptions the simulation engineers have of the task when positioning the manikins. The differences could be minimized by a more careful orderer description and by such activities as simulation engineering days at assembly plants and by bringing the people working with human simulation tools together in the organization. Copyright © 2006 SAE International.
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