Letteratura scientifica selezionata sul tema "Simons' control mechanisms"
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Articoli di riviste sul tema "Simons' control mechanisms"
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Pandithasekara, Dasuni Nirmani, Erabaddage Ayoma Gayathri Sumanasiri e Áron Perényi. "Exploring the Impact of Sustainability Control Systems on Employees’ Green Creativity: The Mediating Role of Psychological Empowerment and Sustainability Learning Capabilities". Sustainability 15, n. 6 (8 marzo 2023): 4806. http://dx.doi.org/10.3390/su15064806.
Testo completoAbstract (sommario):
This paper investigates how sustainability control systems (SCSs) drive employees’ green creativity (EGC) with the purpose of assisting organisations in the Sri Lankan manufacturing sector to improve their environmental sustainability performance. Managers and staff of manufacturing firms often lack awareness of environmental issues, which leads to unsustainable strategies. EGC has been identified as an important resource for devising sustainable strategies. SCSs drive employee behaviour and support EGC by fostering a creative workplace. Utilising Simons’ Levers of Controls (LoC) framework, a mediation model incorporating psychological empowerment (PE) and sustainability learning capabilities (SLCs) is tested to provide insights on how SCSs influence EGS. Survey data collected from 239 organisations in the Sri Lankan manufacturing sector were analysed using the PLS-SEM method. The results confirm the full mediating roles of PE and SLCs on the link between SCSs and EGC. This demonstrates the importance of empowering employees and enhancing their learning capabilities to encourage EGC. This study contributes to Simons’ LoC framework by incorporating sustainability dimensions into management control systems (MCSs), and extends the extant body of knowledge by providing a specific understanding of the mechanisms driving EGC through PE and SLCs.
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Zhao, Liang, Yang Bai, Jie Ma e Yonghui Wang. "Local Control Mechanisms of Implicit and Explicit Conflicts". Experimental Psychology 62, n. 3 (7 maggio 2015): 153–60. http://dx.doi.org/10.1027/1618-3169/a000281.
Testo completoAbstract (sommario):
Congruency sequence effects are observed when the congruency effects following incongruent trials are smaller than those following congruent trials. It is typically assumed that such flexible adjustments are evidence of cognitively controlled dynamic modulations. The present study investigated whether cognitive control acts locally or globally when implicit and explicit conflicts exist simultaneously within a system. The implicit SNARC task and explicit Simon task were combined in a single task. The results showed that congruency effects of one type (e.g., SNARC effect) were only smaller following an incongruent trial of the same type (e.g., SNARC effect), but not when following an incongruent trial of the other type (e.g., Simon effect). These results indicate the operation of local control mechanisms triggered by implicit and explicit conflicts.
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BLUMENFELD, HENRIKE K., e VIORICA MARIAN. "Cognitive control in bilinguals: Advantages in Stimulus–Stimulus inhibition". Bilingualism: Language and Cognition 17, n. 3 (21 novembre 2013): 610–29. http://dx.doi.org/10.1017/s1366728913000564.
Testo completoAbstract (sommario):
Bilinguals have been shown to outperform monolinguals at suppressing task-irrelevant information and on overall speed during cognitive control tasks. Here, monolinguals’ and bilinguals’ performance was compared on two nonlinguistic tasks: a Stroop task (with perceptualStimulus–Stimulus conflictamong stimulus features) and a Simon task (withStimulus–Response conflict). Across two experiments testing bilinguals with different language profiles, bilinguals showed more efficient Stroop than Simon performance, relative to monolinguals, who showed fewer differences across the two tasks. Findings suggest that bilingualism may engage Stroop-type cognitive control mechanisms more than Simon-type mechanisms, likely due to increased Stimulus–Stimulus conflict during bilingual language processing. Findings are discussed in light of previous research on bilingual Stroop and Simon performance.
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Soutschek, Alexander, Hermann J. Müller e Torsten Schubert. "Conflict-Specific Effects of Accessory Stimuli on Cognitive Control in the Stroop Task and the Simon Task". Experimental Psychology 60, n. 2 (1 novembre 2013): 140–48. http://dx.doi.org/10.1027/1618-3169/a000181.
Testo completoAbstract (sommario):
Both the Stroop and the Simon paradigms are often used in research on cognitive control, however, there is evidence that dissociable control processes are involved in these tasks: While conflicts in the Stroop task may be resolved mainly by enhanced task-relevant stimulus processing, conflicts in the Simon task may be resolved rather by suppressing the influence of task-irrelevant information on response selection. In the present study, we show that these control mechanisms interact in different ways with the presentation of accessory stimuli. Accessory stimuli do not affect cognitive control in the Simon task, but they impair the efficiency of cross-trial control processes in the Stroop task. Our findings underline the importance of differentiating between different types of conflicts and mechanisms of cognitive control.
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Salzer, Yael, Daniela Aisenberg, Tal Oron-Gilad e Avishai Henik. "In Touch With the Simon Effect *The first two authors contributed equally." Experimental Psychology 61, n. 3 (1 novembre 2014): 165–79. http://dx.doi.org/10.1027/1618-3169/a000236.
Testo completoAbstract (sommario):
Cognitive control has been extensively studied using the auditory and visual modalities. In the current study, a tactile version of the Simon task was created in order to test control mechanisms in a modality that was less studied, to provide comparative and new information. A significant Simon effect – reaction time gap between congruent (i.e., stimulus and response in the same relative location) and incongruent (i.e., stimulus and response in opposite locations) stimuli – provided grounds to further examine both general and tactile-specific aspects of cognitive control in three experiments. By implementing a neutral condition and conducting sequential and distributional analysis, the present study: (a) supports two different independent mechanisms of cognitive control – reactive control and proactive control; (b) reveals facilitation and interference within the tactile Simon effect; and (c) proposes modality differences in activation and processing of the spatially driven stimulus-response association.
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Struys, Esli, Ghazal Mohades, Peggy Bosch e Maurits van den Noort. "Cognitive Control in Bilingual Children". Swiss Journal of Psychology 74, n. 2 (gennaio 2015): 65–73. http://dx.doi.org/10.1024/1421-0185/a000152.
Testo completoAbstract (sommario):
Studies comparing the cognitive control of bilingual and monolingual speakers are inconclusive about the nature and underlying mechanisms of differences in language-related processing. In the present study, in order to disentangle the impact of second-language onset age of acquisition and bilingualism on cognitive control, we compared a group of bilingual Dutch/French children who had started acquisition of both languages at birth (simultaneous bilingual group) to a group of children who had started acquisition of their second language at the age of 3 years (early bilingual group). Both groups had equal proficiency in the two languages. All participants completed an extensive language test battery in Dutch and French and conducted a linguistic (verbal fluency) and a nonlinguistic cognitive control task (the color Simon task). We found higher global accuracy rates for the simultaneous bilingual group on the Simon task. Surprisingly, we did not find any differences in mean reaction time between the two bilingual groups. In conclusion, this study finds no advantage in terms of verbal fluency, but does reveal that acquiring two languages from birth onward gives simultaneous bilingual children an advantage on the Simon task, even over early bilingual children and when second-language proficiency is held constant.
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Suarez, Isabel, Franck Vidal, Boris Burle e Laurence Casini. "A Dual-Task Paradigm to Study the Interference Reduction in the Simon Task". Experimental Psychology 62, n. 2 (1 marzo 2015): 75–88. http://dx.doi.org/10.1027/1618-3169/a000275.
Testo completoAbstract (sommario):
Analyzing RT distributions in the Simon task reveals that congruency effects decrease for the longest RTs. Four experiments were carried out to examine whether this decrease of the congruency effect with response speed was under a top-down control or due to bottom-up mechanisms. We specifically manipulated the availability of attentional resources by requiring participants to perform a Simon task concurrently to different secondary tasks. RT distribution analysis (in particular delta functions) was performed under both single-task and dual-task conditions. Results show that the reduction of the interference effect with time could be affected when the Simon task was performed concurrently with a secondary task. Nonetheless, the type of the secondary task seems to be a critical factor. Therefore, the data suggest that the mechanisms responsible for the reduction of the interference effect with time are under some attentional control but the exact nature of these mechanisms remains to be explored.
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Mowery, Cody, Jacob Freimer, Jennifer Umhoefer, Christian Garrido, Ralf Schmidt, Zachary Steinhart, Benjamin Gowen et al. "CRISPRi and KO screens reveal integrated cis- and trans-regulation of the CD28, CTLA4, and ICOS locus in primary human T cells". Journal of Immunology 208, n. 1_Supplement (1 maggio 2022): 56.17. http://dx.doi.org/10.4049/jimmunol.208.supp.56.17.
Testo completoAbstract (sommario):
Abstract Costimulation is essential for complete T cell activation, requiring the coordinated expression of various surface proteins including those encoded by CD28 family members CD28, CTLA4, and ICOS. Interestingly, these three genes lie adjacently in a topologically-associating domain (TAD) and are believed to have arisen through duplications of CD28, though they have evolved opposing functions and exhibit expression differences across cell states and T cell subsets. We hypothesized that distinct cis- and trans-regulatory circuits emerged to uniquely govern the expression of each gene. Therefore, we tiled CRISPR interference (CRISPRi) across the 1.44Mb TAD in primary human conventional (Tconv) and regulatory T (Treg) cells to functionally profile cis-regulatory elements (CREs) controlling expression of CD28, CTLA4, and ICOS. We find that inhibiting the transcriptional start site of one gene (but not gene KO) enhances the expression of an adjacent gene, potentially due to redirection of shared CREs to the un-inhibited promoter. Moreover, we find distinct CREs responsible for constitutive expression of CTLA4 in Treg cells but stimulation-responsiveness in Tconv cells. We also find evidence of a single CRE that negatively regulates CD28 at baseline but positively regulates CTLA4 upon restimulation. Lastly, we characterize mechanisms of CRE control by identifying upstream regulators of target genes via CRISPR knockout screening. Our work nominates ZNF217, a zinc finger protein with no known function in human T cells, as a novel negative regulator altering chromatin accessibility in the locus. Here, we present a framework for functional characterization of regulatory modules controlling loci of interest in primary human CD4+ T cells. CM is supported by NIAID F30 AI157167-01 and is a UCSF ImmunoX Computational Immunology Fellow. ZS is supported by the Parker Institute for Cancer Immunology scholarship. RS was supported by fellowships of the Austrian Exchange Service and the Austrian Society of Laboratory Medicine. C.J.Y. and AM are Chan Zuckerberg Biohub Investigators and members of the PICI. C.J.Y. is further supported by the National Institutes of Health (NIH) grant nos. R01AR071522, R01AI136972 and R01HG011239. AM is supported by National Institute of Diabetes and Digestive and Kidney Diseases DP3DK111914-01 (AM) Simons Foundation (AM) Burroughs Wellcome Fund, Career Award for Medical Scientists (AM) The Cancer Research Institute (CRI) Lloyd J. Old STAR grant (AM) Parker Institute for Cancer Immunotherapy, PICI (AM) Innovative Genomics Institute (IGI) National Institutes of Health grant P30 DK063720 (Parnassus Flow Cytometry Core, AM) National Institutes of Health grant S10 1S10OD021822-01 (Parnassus Flow Cytometry Core, AM) Investigator at the Chan Zuckerberg Biohub (AM) Gifts from Brook Byers, Barbara Bakar, Karen Jordan, Elena Radutzky
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Massaro, Maurizio, Andrea Moro e Mike Lucas. "Approcci formali e informali al controllo negli innovation network. La relazione tra Leve del Controllo e Fattori della Fiducia". MANAGEMENT CONTROL, n. 1 (maggio 2012): 27–54. http://dx.doi.org/10.3280/maco2012-001003.
Testo completoAbstract (sommario):
In recent years, there has been a significant increase in inter-organisational collaboration resulting in the emergence of hybrid organisational forms. This has led to recognition that management control can no longer be confined to the boundaries of a single organisation. Management control systems (MCS) must encompass networks of organisations. Inter-organisational relationships require both formal and informal controls. The latter are essentially mechanisms for encouraging self regulation. Significant among these mechanisms is trust. In inter-organisational collaborations high levels of trust can impact on the nature and the role of MCS. This paper elaborates a model of the link between the constituents of trust (trust factors) and the design of the MCS. We show how different trust factors (ability, benevolence, integrity) impact on different MCS' approaches (belief, boundary, diagnostic and interactive systems) using Simon's (1995) levers of control framework. The model demonstrates that an understanding of these relationships, especially in the innovation networks, can help managers employ the most suitable approach to management control in organisational network.
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Forstmann, Birte U., Wery P. M. van den Wildenberg e K. Richard Ridderinkhof. "Neural Mechanisms, Temporal Dynamics, and Individual Differences in Interference Control". Journal of Cognitive Neuroscience 20, n. 10 (ottobre 2008): 1854–65. http://dx.doi.org/10.1162/jocn.2008.20122.
Testo completoAbstract (sommario):
Functional magnetic resonance imaging (fMRI) methods may help in understanding processes of response capture and response inhibition in conflict tasks, such as the Simon task. However, data-driven approaches thus far have not yielded consistent insights into these processes. Here, a theory-driven approach is introduced that capitalizes on individual differences in the processes of central interest. Based on the so-called activation-suppression model, specific behavioral parameters for each individual derived from reaction time (RT) distribution analysis were computed and entered into model-based fMRI analyses. These parameters correspond closely to the processes of inappropriate location-driven response activation (capture) and the subsequent inhibition of this activation as detailed by the model. Data from 24 participants revealed activation in the pre-supplementary motor area, which covaried with the RT distribution measure of response capture. Activation in the right inferior frontal cortex was found to covary with the RT distribution measure of response inhibition. These results, which are consistent against the backdrop of the larger literature on cognitive control, could have been derived neither from the standard data-driven fMRI approach, nor from inspecting overall mean RT alone.
Tesi sul tema "Simons' control mechanisms"
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Flores, Emmanuelle. "Les matrices de matérialité extra-financière : un artefact du pilotage de la stratégie : le cas de la Banque Populaire Alsace Lorraine Champagne". Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCG007.
Testo completoAbstract (sommario):
Cette thèse approfondit le concept de matérialité extra-financière, peu abordé dans la littérature académique, et l’artefact de matrices, socle des publications des informations extra-financières. Cette notion étant empreinte de définitions polysémiques et de référentiels aux lignes directrices nébuleuses, les pratiques actuelles des entreprises manquent de rigueur engendrant des problèmes de transparence et de comparabilité pour les parties prenantes.Aussi, à travers les cadres théoriques de la Théorie Néo-Institutionnelle et de Simons (1995) nous explorons ce concept. Les mécanismes de contrôles mobilisés dans une visée stratégique, en particulier l’interactif et le diagnostique, nous permettent de proposer un modèle de mesure tridimensionnel d’analyse. Il apporte un aspect dynamique à l’évaluation de matérialité en prenant en compte certes les attentes, mais aussi les perceptions et la tendance des parties prenantes. Ce dernier est testé auprès de 10 000 parties prenantes internes et externes dans un contexte de banque coopérative, en particulier la Banque Populaire Alsace Lorraine Champagne. La spécificité de ce terrain de recherche nous amène également à approfondir la notion d’ubiquité et à inclure d’autres parties prenantes que les sociétaires historiquement considérées en tant que tel. Nos résultats mettent en lumière plusieurs apports majeurs comme une innovation processuelle rigoureuse avec des étapes permettant d’élaborer l’artefact des matrices, l’analyse des données statistiques créatrices et porteuses de sens afin de piloter la stratégie de Responsabilité Globale d’une organisation, une typologie des pratiques de matérialité dans les banques coopératives et actionnariales, une typologie des enjeux et le dévoiement des échelles sur l’outil produisant des illusions de consensusThis thesis takes a closer look at the concept of extra-financial materiality, which has received little attention in the academic literature, and the artefact of matrices, the basis for the publication of extra-financial information. As this concept is marked by polysemous definitions and nebulous guidelines, companies' current practices lack rigour, leading to problems of transparency and comparability for stakeholders.Using the theoretical frameworks of Neo-Institutional Theory and Simons (1995), we explore this concept. The control mechanisms mobilised for strategic purposes, in particular the interactive and diagnostic ones, enable us to propose a three-dimensional measurement model for analysis. It adds a dynamic aspect to the assessment of materiality by taking into account not only expectations, but also the perceptions and trends of stakeholders. The model is being tested with 10,000 internal and external stakeholders in the context of a cooperative bank, in particular Banque Populaire Alsace Lorraine The specific nature of this field of research has also led us to explore the notion of ubiquity in greater depth and to include stakeholders other than the members historically considered as such. Our results highlight a number of major contributions, including a rigorous process innovation with stages enabling the matrices artefact to be developed, the analysis of statistical data that creates and conveys meaning in order to steer an organisation's Global Responsibility strategy, a typology of materiality practices in cooperative and shareholder banks, a typology of issues and the misuse of scales on the tool producing illusions of consensus
Capitoli di libri sul tema "Simons' control mechanisms"
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Hochberg, Michael E., e Bradford A. Hawkins. "The implications of population dynamics theory to parasitoid diversity and biological control". In Parasitoid Community Ecology, 451–71. Oxford University PressOxford, 1994. http://dx.doi.org/10.1093/oso/9780198540588.003.0023.
Testo completoAbstract (sommario):
Abstract Insect parasitoids constitute an important and diverse group of taxa. Recent estimates indicate an average of about five to six parasitoid species per insect herbivore species (Askew and Shaw 1986; Hawkins and Lawton 1987; Hawkins 1990; Mills 1992, Chapter 3), although the range extends to almost 100 species (Delucchi 1982). Explaining this range in richness is an important challenge to community ecology. Comparative studies have shown how host feeding niche contributes substantially to explaining variation in parasitoid richness (Hawkins and Lawton 1987; Mills 1993; Hawkins 1993a). Feeding niche has been interpreted as a mechanism generating a ‘refuge’ for those host individuals that are sufficiently (and best) protected from parasitoid attack (Simmonds 1948; Gross 1991; Hawkins and Gross 1992; Hawkins 1993a).
Atti di convegni sul tema "Simons' control mechanisms"
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Vinogradov, Oleg. "On a Model of a Ball in Cluster Impact Problems in Granular Mechanics". In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/pvp-25205.
Testo completoAbstract (sommario):
Abstract The nonlinear damping model introduced by Simon[1] combined with the Hertz model of contact elastic forces is applied to a two- and a multi-ball chain-type system (Newton’s Cradle). The numerical investigation is focused on inter-dependence between the numerical efficiency and accuracy for two- and a multi-ball system. An error control damping is introduced, which allows increased computational efficiency and at the same time error reduction.
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Creighton, J. R., e C. M. Truong. "Surface Chemistry of GaAs Atomic Layer Epitaxy". In Microphysics of Surfaces: Nanoscale Processing. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/msnp.1995.mthc1.
Testo completoAbstract (sommario):
Atomic layer epitaxy (ALE) is a technique which, in principle, yields unparalleled deposition uniformity with precise (i.e. monolayer) thickness control. The technique has been used to deposit compound semiconductors, e.g. GaAs, although the success has not been universally good. In many examples the ALE operating “window” is very small or non-existent. Unintentional carbon doping is another problem which has limited the utility of this technique. In order to address the problems limiting GaAs ALE, we have investigated the surface chemical properties of the standard deposition precursors on GaAs(100) using a variety of surface science diagnostics. Results of these experiments have shed light on the mechanisms of precursor decomposition which lead to film growth and carbon doping. For instance, the kinetics of trimethylgallium (TMGa) decomposition on the Ga-rich and As-rich surfaces, measured by TPD, are in semiquantitative agreement with ALE results. This indicates that the dominant growth mechanism during ALE is heterogeneous in nature. We have also investigated the mechanism of carbon incorporation when using TMGa. Normally, a small fraction of adsorbed methyl (CH3) groups dehydrogenate into methylene (CH2) groups, which are a likely precursor to carbon incorporation. This adsorbate was characterized with vibrational spectroscopies and static SIMS. The rate of CH3 dehydrogenation is consistent with the carbon doping levels obtained during ALE and MOMBE.
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Skaare, Bjo̸rn, Tor David Hanson e Finn Gunnar Nielsen. "Importance of Control Strategies on Fatigue Life of Floating Wind Turbines". In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29277.
Testo completoAbstract (sommario):
Exploitation of wind energy at deep-waters locations requires floating wind turbine foundations. Several floating wind turbine foundation concepts are reported in the literature, and a common challenge is to make a low cost foundation with acceptable motion characteristics. In order to analyze the fatigue life of floating offshore wind turbines, the coupled action of wind, waves, current and blade pitch control strategy must be considered. State-of-the-art computer programs for motion analysis of moored offshore bodies, Simo-Riflex from Sintef Marintek, are coupled to a state-of-the-art aero-elastic computer program for wind turbines, Hawc2 from Riso̸ National Laboratory. The wave loads on the body may include wave diffraction and radiation loads as well as viscous forces. The mooring lines are modelled using cable finite elements with inertia and drag forces. The wind load on the rotor is based on common rotor aerodynamics including corrections for skew inflow and relative motion caused by large displacement and large tilt and yaw rotations of the rotor. Conventional wind turbine control strategies lead to wind-induced loads that may amplify or damp the motions of the floating wind turbine. The first case is a result of the blade pitch control strategy above rated wind speed for the wind turbine, and can result in large resonant motions that will reduce the fatigue life of the floating wind turbine significantly. The latter case implies energy extraction from the waves. This paper addresses the importance of control strategies on fatigue life for a given floating offshore wind turbine. A fatigue life time comparison between a conventional blade pitch control strategy and an estimator based blade pitch control strategy show that the fatigue life of floating offshore wind turbines can be significantly increased by use of alternative blade pitch control strategies.
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Galbraith, Marshall C., Amit Kasliwal, Kirti Ghia e Urmila Ghia. "Numerical Simulation of a Low Pressure Turbine Blade Employing Active Flow Control". In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98566.
Testo completoAbstract (sommario):
High altitude aircraft experience a large drop in the Reynolds number (Re) from take off conditions to cruise conditions. It has been shown in previous research performed by Simon and Volino [1] that this reduction in Re number causes the flow inside the turbine cascades to become laminar, and separate more readily on the suction side of the turbine blade. This boundary-layer separation greatly reduces the efficiency of the turbine and aircraft engine as a whole, and therefore is undesirable. To prevent this loss of efficiency, research will be pursued for active and passive means to delay and/or eliminate the flow separation. Lake et al. [2] used passive boundary layer trip, dimples, and V-grooves in an extensive study to reduce separation on the Pak-B turbine blade. Although these passive techniques were able to reduce the separation at fixed Re numbers, an active flow control method is needed for more efficient separation reduction over a range of Re numbers. Currently, researchers are investigating several different active flow control devices, including pulsating synthetic jets, vortex generator jets (VGJ), and moving protuberances. The proposed study intends to further investigate the mechanism of flow control via synthetic jets, which alternate between suction and blowing, on a low pressure turbine blade utilizing a Large Eddy Simulation (LES) Computational Fluid Dynamics (CFD) solver. Optimum values of the associated parameters such as jet angle, blowing ratio, frequency, duty cycle, etc., of the synthetic jets will be determined. However, before investigation of the effectiveness of synthetic jets, the CFD simulation will be validated with experimental data on VGJ. A description of the implementation is presented along with preliminary results.
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Sankur, Haluk O., William H. Southwell e Randolph L. Hall. "In situ observation of compositional gradients during OM-VPE growth of AlxGa1-xAs". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.thm3.
Testo completoAbstract (sommario):
Many optical and optoelectronic device properties depend on the precise control of the composition and thickness of the layers and on the abruptness of compositional steps. Properly designed gas delivery systems in OM-VPE reactors can achieve abrupt steps in gas composition, but not necessarily in the solid material of the epilayers. We have observed composition gradients at the interfaces, during OM-VPE deposition of AlxGa1-xAs, by in situ optical reflection and postdeposition spectrophotometry. A depth profile of the composition was measured by sputtering SIMS and it was compared to the profile obtained by the analysis of in situ reflectance and spectral data. This work demonstrates the presence of compositional gradients in OM-VPE-grown materials, even when the gas-delivery system is designed to achieve abrupt steps in gas composition. Possible mechanisms for the formation of gradients, techniques to achieve abrupt composition steps in the layers, and the usefulness of in situ techniques to characterize the OM-VPE deposition of semiconductors will be discussed.
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Dressler, Nils, e Lars Eriksson. "Implementation of a bolted joint model in Modelica". In 64th International Conference of Scandinavian Simulation Society, SIMS 2023 Västerås, Sweden, September 25-28, 2023. Linköping University Electronic Press, 2023. http://dx.doi.org/10.3384/ecp200023.
Testo completoAbstract (sommario):
The basic mechanics of a bolted joint are well-known and have been studied for a long time. The dominating principle is to represent the parts in a joint as a series connection of linear compression and tension springs. However, traditional models often neglect the tightening dynamics and their interrelation with, for instance the friction or embedment. To study these phenomena further and determine their impact on the tightening process and dynamics, and for developing new tightening control strategies, it is necessary to model a threaded fastener and implement it in a suitable simulation environment.Existing models and experimental data have been studied to find equations that fit the observed behavior. Novel models were combined with standard Modelica components to form a threaded fastener model. The simulation results were compared with tightening data from experiments. This work proposes new models for the first three tightening phases, embedment, and threaded fastener friction. These models are implemented in the modeling language Modelica. The results show that it is possible to resemble a typical threaded fastener tightening with power tools. The friction and tightening phases show the expected behavior, while the embedment model needs further experimental verification. During modeling, the model is susceptible to the chosen parameters. Parameters for the joint stiffness, obtained via the VDI guidelines, needed to be reduced by 30% to resemble the joint in a dynamic simulation.