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Artykuły w czasopismach na temat "Environmental load theory"
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Okada, Norio, i Atushi Nishikori. "A Game Theory lodel of the Environmental Load Allocation". INFRASTRUCTURE PLANNING REVIEW 3 (1986): 65–72. http://dx.doi.org/10.2208/journalip.3.65.
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Attia, Mohamed A., Ammar Melaibari, Rabab A. Shanab i Mohamed A. Eltaher. "Dynamic Analysis of Sigmoid Bidirectional FG Microbeams under Moving Load and Thermal Load: Analytical Laplace Solution". Mathematics 10, nr 24 (16.12.2022): 4797. http://dx.doi.org/10.3390/math10244797.
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This paper presents for the first time a closed-form solution of the dynamic response of sigmoid bidirectional functionally graded (SBDFG) microbeams under moving harmonic load and thermal environmental conditions. The formulation is established in the context of the modified couple stress theory to integrate the effects of microstructure. On the basis of the elasticity theory, nonclassical governing equations are derived by using Hamilton’s principle in combination with the parabolic higher-order shear deformation theory considering the physical neutral plane concept. Sigmoid distribution functions are used to describe the temperature-dependent thermomechanical material of bulk continuums of the beam in both the axial and thickness directions, and the gradation of the material length scale parameter is also considered. Linear and nonlinear temperature profiles are considered to present the environmental thermal loads. The Laplace transform is exploited for the first time to evaluate the closed-form solution of the proposed model for a simply supported (SS) boundary condition. The solution is verified by comparing the predicted fundamental frequency and dynamic response with the previously published results. A parametric study is conducted to explore the impacts of gradient indices in both directions, graded material length scale parameters, thermal loads, and moving speed of the acted load on the dynamic response of microbeams. The results can serve as a principle for evaluating the multi-functional and optimal design of microbeams acted upon by a moving load.
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Clement, A. "Improving uncertain nutrient load estimates for Lake Balaton". Water Science and Technology 43, nr 7 (1.04.2001): 279–86. http://dx.doi.org/10.2166/wst.2001.0436.
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Annual nutrient loads have been estimated for Lake Balaton over three decades. Tributaries may transport about half of the loads into the lake. The contribution of diffuse sources may reach two thirds of the total load. Biweekly/monthly water quality monitoring on small inflows (0.01 m3/s-0.3 m3/s range) results in a high uncertainty of load estimates. This paper evaluates the degree of uncertainties by using analytical expressions of sampling theory. Load-flow relationships were derived for five streams and annual total phosphorus load was predicted by four load estimation methods. A seasonal regression model, based upon the evaluation of historical set of observed phosphorus loads, appeared best to refine load estimates on small inflows. Correction frequently led to load estimates that exceeded uncorrected loads by a factor of two to three. Since the dynamics of the watercourses determined the errors of load estimates, stratified sampling is needed to decrease the uncertainties.
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Hueckel, Tomasz A. "Water–mineral interaction in hygromechanics of clays exposed to environmental loads: a mixture-theory approach". Canadian Geotechnical Journal 29, nr 6 (1.12.1992): 1071–86. http://dx.doi.org/10.1139/t92-124.
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Water–mineral interaction in narrow interstices (<30 Å (1 Å = 0.1 nm)) in dense, saturated clays is discussed in view of recent experimental findings and molecular dynamics simulations. Consequences to the macroscopic behavior are considered. A mixture theory for two interacting constituents is developed. Effects of temperature and chemicals are discussed. A postulate of mass transfer of adsorbed water from solid to fluid fraction caused by thermal or chemical load is then discussed. Theory of plasticity of clays affected by heat or chemicals is developed to deal with the effects of thermal and chemical consolidation. Key words : hydraulic conductivity, effective stress, environmental loads, thermo-chemo-plasticity.
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Jung, Sooyoung, Yong Tae Yoon i Jun-Ho Huh. "An Efficient Micro Grid Optimization Theory". Mathematics 8, nr 4 (10.04.2020): 560. http://dx.doi.org/10.3390/math8040560.
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A Micro Grid is an aggregate of many small-scale distributed energy resources (DERs); loads and can be operated independently or together with the existing power grid as a local power grid. The operator of such a grid takes charge of the energy supply and consumption of these resources and loads available in the grid. Meanwhile, the system operator of the grid considers the entire Micro Grid system to be a single load or a generator and assigns the responsibility of its internal management to the operator. The power production from a passive production resource is largely influenced by external environmental factors such as weather conditions, rather than operating conditions. Thus, this study conducted simulations for the cases where four kinds of conditional expressions had not been applied at all or one of them had been applied to compare and evaluate the effectiveness of each expression. As a result, the conditional equations were found to be effective when attempting to optimize the Micro Grids efficiently.
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Hu, Bo, Nan Wang, Zaiming Yu, Yunqing Cao, Dongsheng Yang i Li Sun. "Optimal Operation of Multiple Energy System Based on Multi-Objective Theory and Grey Theory". Energies 15, nr 1 (22.12.2021): 68. http://dx.doi.org/10.3390/en15010068.
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The manufacturing industry consumes electricity and natural gas to provide the power and heat required for manufacturing. Additionally, large amounts of electric energy and heat energy are used, and the electricity cost, amount of environmental pollution, and equipment maintenance cost are high. Thus, optimizing the management of equipment with new energy is important to satisfy the load demand from the system. This paper formulates the scheduling problem of these multiple energy systems as a multi-objective linear regression model (MLRM), and an energy management system is designed focusing on the economy and on greenhouse gas emissions. Furthermore, a variety of optimization objectives and constraints are proposed to make the energy management scheme more practical. Then, grey theory is combined with the common MLRM to accurately represent the uncertainty in the system and to make the model better reflect the actual situation. This paper takes load fluctuation, total grid operation cost, and environmental pollution value as reference standards to measure the effect of the gray optimization algorithm. Lastly, the model is applied to optimize the energy supply plan and its performance is demonstrated using numerical examples. The verification results meet the optimized operating conditions of the multi-energy microgrid system.
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Jorgenson, Andrew K. "The sociology of ecologically unequal exchange, foreign investment dependence and environmental load displacement: summary of the literature and implications for sustainability". Journal of Political Ecology 23, nr 1 (1.12.2016): 334. http://dx.doi.org/10.2458/v23i1.20221.
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The article begins by summarizing sociological approaches to (1) ecologically unequal exchange, and (2) foreign investment dependence and environmental load displacement. These areas of sociological inquiry consist of structural theories and cross-national statistical analyses that test hypotheses derived from both approaches. It concludes by briefly describing sociological research on global civil society and the environment, with a focus on the world society approach to environmental change. This area of theory and research provides some insights on ways in which global and transnational civil society groups, such as environmental international nongovernmental organizations, can partially mitigate the environmental harms caused by ecologically unequal exchanges and environmental load displacements.Key words: ecologically unequal exchange, environmental load displacement, foreign investment dependence
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Kato, Seizo, Naoki Maruyama, Yasuki Nikai, Hidekazu Takai i Anugerah Widiyanto. "Life Cycle Assessment Estimation for Eco-Management of Co-Generation Systems". Journal of Energy Resources Technology 123, nr 1 (30.10.2000): 15–20. http://dx.doi.org/10.1115/1.1345732.
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A LCA (life cycle assessment) scheme for any industrial activity system is introduced to estimate the quantitative load on the environment with the aid of the NETS (numerical environment total standard) method proposed by the authors as a numerical measure. Two kinds of environmental loads respecting fossil fuel depletion as input resources to the system and global warming due to CO2 emission as output are taken into account in the present eco-criterion, in which the total eco-load (EcL) value is calculated from the summation of respective environmental load factors on the whole process in a life cycle of the system. This NETS method is applied to eco-management co-generation systems, in which a computer-aided output navigator proceeds the LCA estimation with ICON and Q&A communication. An operation scheme most friendly to the environment with a minimum EcL value, i.e., an eco-operation scheme, is derived from the optimization theory.
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Ren, Yue, i Yue Zhao. "Studies on the Environmental Impact of the HVAC Equipments Based on the LCA Theory". Applied Mechanics and Materials 694 (listopad 2014): 417–21. http://dx.doi.org/10.4028/www.scientific.net/amm.694.417.
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We chose an endpoint damage model and combined it with ecological index method to obtain the life cycle assessment model of HVAC equipment. The environmental load was calculated which included the production of room air conditioners and water chillers. The environmental impact of the HVAC industry in China was analyzed quantitatively at a macroeconomic level. And the energy saving strategy was analyzed.
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Perelmuter, Anatolii. "Theory of structures and design codes". Strength of Materials and Theory of Structures, nr 108 (30.05.2022): 3–16. http://dx.doi.org/10.32347/2410-2547.2022.108.3-16.
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Building structures should correspond to the reliability requirements which are implemented with the help of design codes. The latter are based on the method of limit states. In order to simplify the verifications, the design codes often deliberately deviate from the scientifically based theoretical provisions of such fundamental disciplines as the theory of elasticity and the theory of plasticity, replacing them with the so-called working practices. The paper presents that there are inaccurately formulated recommendations in the design codes. The paper also specifies on some important problems that are not reflected in the design codes. This applies to the choice of failure probability values, the use of partial reliability factors, the calculation methodology in case of an emergency, the problems of using the results of nonlinear calculation, etc.
The paper presents some considerations on these issues, with the main attention being paid to the analysis of the existing design tradition and guidance to unresolved issues. The problems of recommended reliability parameters, clarification of the limit state concepts, analysis of accidental situations, the safety factors values and possible relationship between the safety factors for load and the safety factors for materials, loads and load effects, vulnerability assessment as well as reliability of protected systems have been considered.
The considerations presented by the paper give only a partial idea of the range of issues that arise when comparing working practices used in the design codes with the theoretical fundamentals they should correspond to. It should also be noted that the design codes do not provide any justifications for their recommendations. The presented paper can initiate a scientific discussion and be useful both for the developers of design codes and for the developers of software packages implemented the design codes.
Rozprawy doktorskie na temat "Environmental load theory"
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Richardson, Christine Rosalie, i n/a. "Symbolism in the Courtroom: An Examination of the Influence of Non-Verbal Cues in a District Court Setting on Juror Ability to Focus on the Evidence". Griffith University. School of Criminology and Criminal Justice, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070314.095406.
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Described in this thesis is research that examined the influence of courtroom symbolism on jurors' ability to focus on the evidence presented in a criminal trial. This research is unique as participants were 'real' jurors who had, at the time of participation in the research, recently completed deliberations on a District Court trial. To date no other research has explored the interaction between symbolism in the courtroom and the juror experience. The broad research question examined in this research was: Do symbolic elements in the courtroom environment draw juror attention away from the evidence being presented?. Three theories drawn from environmental psychology were utilised in this research (i.e., environmental uncertainty theory, environmental arousal theory and environmental load theory). Additionally, Rapoport's (1983, 1990) theory, which was drawn from the architectural field of knowledge, was utilised. Rapoport's theory facilitated the measurement of symbolism in the form of environmental cues found in the courtroom. To address the broad research question, eight subordinate research questions were formulated those being: (1) Do trait anxiety and court related factors influence the amount of attention jurors pay to the elements of the courtroom environment?, (2) Do trait anxiety and court related factors influence the effect on jurors of the attention they paid to the elements of the courtroom environment?, (3) Do trait anxiety and court related factors influence the sense of stress or arousal in jurors?, (4) Is there an association between attention paid by jurors to the environmental cues found in the courtroom, their ability to perform their role as a juror and their sense of appreciation for the function of the law?, (5) Is there an association between attention paid by jurors to the environmental cues in the courtroom and a state of elevated stress?, (6) Does the amount of attention paid by jurors to environmental cues found in the courtroom diminish over time?, (7) Does the effect on jurors of the attention they paid to the environmental cues in the courtroom diminish over time? and, (8) Does the amount of stress jurors experience diminish over time?. The eight research questions were addressed in two studies. The first involved a survey of jurors who had completed deliberations in District Court trials in Brisbane and Cairns during the period 19th July, 2001 and 18th July, 2002 (N=192). This study examined the amount of attention jurors paid to four elements of the courtroom environment (i.e., the courtroom design, the appearance and behaviour of court officials, the appearance and behaviour of those associated with the offence and the task of being a juror). Also examined in this study was the influence on jurors of the attention they paid to the elements of the courtroom environment. Juror experience of state anxiety as measured by the State Trait Anxiety Inventory [STAI] (Spielberger, 1983) was also examined. Additionally, the influence of trait anxiety as measured by the STAI (Spielberger, 1983) and court related factors (i.e., location of trial, prior jury experience, nature of the offence and length of trial) on the juror experience was examined. Two time frames were examined (i.e., initial contact with the courtroom and midpoint of juror experience) which allowed the examination of the influence of time on the juror experience. Interviews with jurors who had completed the survey (N=19) comprised the second study. This study allowed jurors to describe their experience on a jury from a more personal perspective. The elements of the juror experience that distracted and reinforced their ability to focus on the evidence and facilitated a sense of appreciation for the function of the law were discussed. Also discussed were the elements of the juror experience that caused jurors to experience anxiety. Overall, the findings of this research indicated that although symbolism in the courtroom was linked to juror anxiety, this was positive and facilitated juror attention to the evidence and a sense of respect for the criminal justice system. That anxiety experienced by jurors facilitated their focus on the evidence is consistent with environmental arousal theory in that for optimum performance one must experience a certain level of arousal. Also confirmed by the findings of this research is environmental load theory, an element of which predicts that jurors will be task driven when experiencing environmental load. That these two theories are linked by an underlying construct is evidenced by the findings of this research. These findings open up possibilities for future theoretical research using environmental arousal theory and environmental load theory. The findings of this research also suggest that jurors found the symbolism in the courtroom environment distracting and that some elements of the juror experience were onerous and stressful. However, previous experience in the courtroom and lower trait anxiety moderated these factors. Consequently, consistent with the results of this research courts might benefit from implementing an orientation program for prospective jurors such that they are familiarised with the courtroom environment. Such a program would moderate any distress experienced by jurors. In the context of such adjustments by the courts, the influence of symbolism in the courtroom are considered beneficial to the juror experience and there is no need for the courts to alter the courtroom setting or robing practices of lawyers.
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Richardson, Christine Rosalie. "Symbolism in the Courtroom: An Examination of the Influence of Non-Verbal Cues in a District Court Setting on Juror Ability to Focus on the Evidence". Thesis, Griffith University, 2007. http://hdl.handle.net/10072/367555.
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Described in this thesis is research that examined the influence of courtroom symbolism on jurors' ability to focus on the evidence presented in a criminal trial. This research is unique as participants were 'real' jurors who had, at the time of participation in the research, recently completed deliberations on a District Court trial. To date no other research has explored the interaction between symbolism in the courtroom and the juror experience. The broad research question examined in this research was: Do symbolic elements in the courtroom environment draw juror attention away from the evidence being presented?. Three theories drawn from environmental psychology were utilised in this research (i.e., environmental uncertainty theory, environmental arousal theory and environmental load theory). Additionally, Rapoport's (1983, 1990) theory, which was drawn from the architectural field of knowledge, was utilised. Rapoport's theory facilitated the measurement of symbolism in the form of environmental cues found in the courtroom. To address the broad research question, eight subordinate research questions were formulated those being: (1) Do trait anxiety and court related factors influence the amount of attention jurors pay to the elements of the courtroom environment?, (2) Do trait anxiety and court related factors influence the effect on jurors of the attention they paid to the elements of the courtroom environment?, (3) Do trait anxiety and court related factors influence the sense of stress or arousal in jurors?, (4) Is there an association between attention paid by jurors to the environmental cues found in the courtroom, their ability to perform their role as a juror and their sense of appreciation for the function of the law?, (5) Is there an association between attention paid by jurors to the environmental cues in the courtroom and a state of elevated stress?, (6) Does the amount of attention paid by jurors to environmental cues found in the courtroom diminish over time?, (7) Does the effect on jurors of the attention they paid to the environmental cues in the courtroom diminish over time? and, (8) Does the amount of stress jurors experience diminish over time?. The eight research questions were addressed in two studies. The first involved a survey of jurors who had completed deliberations in District Court trials in Brisbane and Cairns during the period 19th July, 2001 and 18th July, 2002 (N=192). This study examined the amount of attention jurors paid to four elements of the courtroom environment (i.e., the courtroom design, the appearance and behaviour of court officials, the appearance and behaviour of those associated with the offence and the task of being a juror). Also examined in this study was the influence on jurors of the attention they paid to the elements of the courtroom environment. Juror experience of state anxiety as measured by the State Trait Anxiety Inventory [STAI] (Spielberger, 1983) was also examined. Additionally, the influence of trait anxiety as measured by the STAI (Spielberger, 1983) and court related factors (i.e., location of trial, prior jury experience, nature of the offence and length of trial) on the juror experience was examined. Two time frames were examined (i.e., initial contact with the courtroom and midpoint of juror experience) which allowed the examination of the influence of time on the juror experience. Interviews with jurors who had completed the survey (N=19) comprised the second study. This study allowed jurors to describe their experience on a jury from a more personal perspective. The elements of the juror experience that distracted and reinforced their ability to focus on the evidence and facilitated a sense of appreciation for the function of the law were discussed. Also discussed were the elements of the juror experience that caused jurors to experience anxiety. Overall, the findings of this research indicated that although symbolism in the courtroom was linked to juror anxiety, this was positive and facilitated juror attention to the evidence and a sense of respect for the criminal justice system. That anxiety experienced by jurors facilitated their focus on the evidence is consistent with environmental arousal theory in that for optimum performance one must experience a certain level of arousal. Also confirmed by the findings of this research is environmental load theory, an element of which predicts that jurors will be task driven when experiencing environmental load. That these two theories are linked by an underlying construct is evidenced by the findings of this research. These findings open up possibilities for future theoretical research using environmental arousal theory and environmental load theory. The findings of this research also suggest that jurors found the symbolism in the courtroom environment distracting and that some elements of the juror experience were onerous and stressful. However, previous experience in the courtroom and lower trait anxiety moderated these factors. Consequently, consistent with the results of this research courts might benefit from implementing an orientation program for prospective jurors such that they are familiarised with the courtroom environment. Such a program would moderate any distress experienced by jurors. In the context of such adjustments by the courts, the influence of symbolism in the courtroom are considered beneficial to the juror experience and there is no need for the courts to alter the courtroom setting or robing practices of lawyers.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Criminology and Criminal Justice
Faculty of Arts
Full Text
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Grieve, Susan M. "Cognitive Load Theory Principles Applied to Simulation Instructional Design for Novice Health Professional Learners". Diss., NSUWorks, 2019. https://nsuworks.nova.edu/hpd_pt_stuetd/78.
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While the body of evidence supporting the use of simulation-based learning in the education of health professionals is growing, howor why simulation-based learning works is not yet understood. There is a clear need for evidence, grounded in contemporary educational theory, to clarify the features of simulation instructional design that optimize learning outcomes and efficiency in health care professional students.
Cognitive Load Theory (CLT) is a theoretical framework focused on a learner’s working memory capacity. One principle of CLT is example based learning. While this principle has been applied in both traditional classroom and laboratory settings, and has shown positive performance and learning outcomes, example based learning has not yet been applied to the simulation setting. This study had two main objectives: to explore if the example-based learning principle could successfully be applied to the simulation learning environment, and to establish response process validation evidence for a tool designed to measure types of cognitive load.
Fifty-eight novice students from nursing, podiatric medicine, physician assistant, physical and occupational therapy programs participated in a blinded randomized control study. The dependent variable was the simulation brief. Participants were randomly assigned to either a traditional brief or a facilitated tutored problem brief. Performance outcomes were measured with verbal communications skill presented in the Introduction, Situation, Background, Assessment, Recommendation (I-SBAR) format. Response process evidence was collected from cognitive interviews of 11 students.
Results indicate participation in a tutored problem brief led to statistically significant differences at t(52)=-3.259, p=.002 in verbal communication performance compared to students who participated in a traditional brief. Effect size for this comparison was d=(6.06-4.61)/1.63 = .89 (95% CI 0.32-1.44). Response process evidence demonstrated that additional factors unique to the simulationlearning environment should be accounted for when measuring cognitive load in simulation based learning (SBL).
This study suggests that example based learning principles can be successfully applied to SBL and result in positive performance outcomes for health professions students. Additionally, measures of cognitive load do not appear to capture all contribution toload imposed by the simulation environment.
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Snyder, Jeffrey L. "Full-Scale Lateral-Load Tests of a 3x5 Pile Group in Soft Clays and Silts". Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd364.pdf.
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Karaduman, Gulsah. "Scheduling Approaches For Parameter Sweep Applications In A Heterogeneous Distributed Environment". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612562/index.pdf.
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In this thesis, the focus is on the development of scheduling algorithms for Sim-PETEK which is a framework for parallel and distributed execution of simulations. Since it is especially designed for running parameter sweep applications in a heterogeneous distributed computational environment, multi-round and adaptive scheduling approaches are followed. Five different scheduling algorithms are designed and evaluated for scheduling purposes of Sim-PETEK. Development of these algorithms are arranged in a way that a newly developed algorithm provides extensions over the previously developed and evaluated ones. Evaluation of the scheduling algorithms is handled by running a Wireless Sensor Network (WSN) simulation over Sim-PETEK in a heterogeneous distributed computational system formed in TUBITAK UEKAE ILTAREN. This evaluation not only makes comparisons among the scheduling algorithms but it also and rates them in terms of the optimality principle of divisible load theory which mentions that in order to obtain optimal processing time all the processors used in the computation must stop at the same time. Furthermore, this study adapts a scheduling approach, which uses statistical calibration, from literature to Sim-PETEK and makes an assessment between this approach and the most optimal scheduling approach among the five
algorithms that have been previously evaluated. The approach which is found to be the most efficient is utilized as the Sim-PETEK scheduler.
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Kilic, Eylem. "The Effects Of Cognitive Load In Learning From Goal Based Scenario Designed Multimedia Learning Environment For Learners Having Different Working Memory Capacities". Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611404/index.pdf.
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ABSTRACT
THE EFFECTS OF COGNITIVE LOAD IN LEARNING FROM GOAL BASED SCENARIO DESIGNED MULTIMEDIA LEARNING ENVIRONMENT FOR LEARNERS HAVING DIFFERENT WORKING MEMORY CAPACITIES
Kiliç, Eylem Ph.D., Department of Computer Education and Instructional Technology Supervisor: Assoc. Prof. Dr. Zahide Yildirim December 2009, 201 pages The purpose of this study is to investigate the effects of principles aiming to reduce extraneous cognitive load in learning from goal based scenario designed multimedia learning environment for learners having different working memory capacities. In addition, the effects of goal based scenario and the principles of cognitive load theory on students&rsquo
perception, motivation and satisfaction has been explored. Two versions of the multimedia were developed for this study. In the first version (+CLT), the principles such as split attention, multimedia, modality, redundancy, coherence and signaling was applied. In the second version (-CLT), these principles were violated. Mixed method was used and two studies were conducted for this study. The first study was conducted with 82 ninth grade students from one of the Anatolian High School in Ankara. However, the participants&rsquo
working memory capacities were found very close to each other. Therefore, the second study was conducted with 54 11th grade students having different working memory capacity from the same school. The result of the first study showed that the cognitive load principles aim at reducing extraneous cognitive load increased learning gains, decreased invested mental effort and affected students&rsquo
motivation and satisfaction in positive ways. On the other hand, when cognitive load principles were not considered, this decreased learning gains, increased invested mental effort and affected students&rsquo
motivation and satisfaction in negative ways. The result of the second study showed that the only difference between high and low WMC students found on the number of errors made in sequencing meiosis sub phases in favor of the first version (+CLT). This might be explained by the task characteristics in that the difference between high and low WMC individuals can be observed when task demanded attention. It can be concluded that students benefited from the cognitive load principles reducing extraneous cognitive based on the findings of both studies.
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Lambrechtsen, Frans Joseph. "Second-Order Perturbation Analysis of the St. Venant Equations in Relation to Bed-Load Transport and Equilibrium Scour Hole Development". BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4274.
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This analysis is an expansion of research done by Rollin Hotchkiss during his Ph.D work. The research uses fluid flow, sediment transport, and perturbation theory to predict where scour will occur in a variable-width channel. The resulting equations also determine equilibrium scour depth based upon the stream bed elevation derived from a dimensionless bed slope equation. Hotchkiss perturbed the width of the channel using a second order Taylor Series perturbation but neglected second order terms. The present work follows the same procedures as Hotchkiss but maintains the second order terms. The primary purpose is to examine how the additional terms impact the final equilibrium scour depth and location results. The results of this research show a slight variation from the previous work. With respect to a hypothetical case, there was not a significant amount of change, thereby verifying that scour migrates downstream with an increase in discharge. Interestingly, the comparison shows a slight increase in sediment discharge through the test reach analyzed. Supplementary to previous research, values of scour depth and location in terms of distance from the start of channel-width perturbation are provided; at the lowest discharge maximum scour occurs 4% of a wavelength upstream of the narrowest portion, and at the highest discharge maximum scour occurs at the narrowest point. Additionally, a one-dimensional HEC-RAS sediment transport model and a two- dimensional SRH flow model were compared to the analytical results. Results show that the model output of the HEC-RAS model and the SRH model adequately approximate the analytical model studied. Specifically, the results verify that maximum scour depth transitions downstream as discharge increases.
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Rogers, Jock Alexander McDonald. "Minimising Extraneous Cognitive Load in Immersive Virtual Environments: Evaluating an Immersive Virtual Reality Educational Platform Against the Principles of Cognitive Load Theory". Thesis, 2019. http://hdl.handle.net/2440/120342.
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This item is only available electronically.Many consider STEM skills to be increasingly important for the future workplace. However, Australian enrolments in senior secondary STEM subjects declined through the 90s and early 2000s, especially in science subjects. The number of enrolments plateaued and has changed little since. One reasons behind this is that students tend to avoid and dropout of STEM subjects. This is partly because STEM education across Australia is not fostering enough interest in students, and a lack of engagement and enjoyment in the classroom. STEM Classrooms need to be made more interesting, engaging and enjoyable, but in a way that does not harm learning. Immersive Virtual Reality (IVR) is uniquely positioned for this as it can create novel, authentic, immersive, interactive and emotional experiences. These experiences immerse users within the virtual environment (VE), establishing a sense of presence or ‘being there’. Presence and authenticity create unmediated and engaging experiences, of the type recommended by most modern learning theories. However, IVR comes with many limitations, of which cost is the most notable. Furthermore, there are significant gaps in the literature describing and demonstrating the relation between the countless factors that define IVR, and learning outcomes. So far studies have demonstrated that IVR is often not superior, and sometimes inferior, to traditional methods with respect to cognitive learning outcomes. A problem which is exacerbated by the fact that few of the many IVR devices and software developed are grounded in solid pedagogy. Early research has indicated why this might be the case, the answer might come from Cognitive Load Theory (CLT). CLT is a learning theory especially suited for describing the cognitive loads associated with learning tasks and the methods to manage and reduce it. IVR is often informationally dense, requiring that students navigate a full 360˚, 3D virtual environment whilst being dazzled by many sources of visual and sometimes audial information. CLT suggests that cognitive load comes in two forms. One of these, extraneous load, encompasses content that is irrelevant to learning that either distracts students, or forces them to process it alongside task-relevant information. IVR, it is suggested, tends to create large extraneous loads, which is possibly the source of its mediocre performance in producing cognitive learning outcomes. The goal of this study was to use the principles of CLT to evaluate an educational IVR platform with regards to minimising extraneous load. This platform could support large numbers of users simultaneously within shared or separate VEs whilst an instructor, using a separate non-IVR device, selected, controlled and manipulate the content. After a review of the literature, two questions would define the evaluation: Q1) How does the educational IVR platform compare to the recommendations of CLT regarding the reduction of extraneous load in the presentation of content? Q2) Where & how could the educational IVR platform be changed to better meet the recommendations? The evaluation was conducted by directly using the platform, during which the platform’s content was qualitatively observed and its characteristics explored. These observations were conducted using a coding framework consisting of criteria that was synthesised from the principles of CLT and the characteristics, capabilities and limitations of the platform initially identified. The observations were analysed and discussed, in these discussions content design methods based off the criteria were suggested. More importantly, the interaction between the defining characteristics of the platform and the criteria was determined, from which the primary evaluation and recommendations were made. The evaluation concluded that the platform was well suited for minimising extraneous load for several reasons (Q1). Some simple recommendations were made, primarily the addition of more tools for the instructor to use to manipulate running content (Q2). By attempting to evaluate an ICT technology, the research aimed to guide or assist future evaluations. However, due to limitations in the literature and research method, assumptions had to be made. The limitations that necessitated these assumptions provided a basis for suggested research directions.
Thesis (MTeach) -- University of Adelaide, School of Education, 2019
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Ward, Elena. "An Examination of the Effects of Mathematics Anxiety, Modality, and Learner-Control on Teacher Candidates in Multimedia Learning Environments". Thesis, 2008. http://hdl.handle.net/1974/1520.
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This study examined mathematics anxiety among elementary teacher candidates, and to what extent it interacted with the modality principle under various degrees of learner-control. The experiment involved a sample of 186 elementary teacher candidates learning from eight versions of a computer program on division with fractions. The eight versions varied in modality of presentation (diagrams with narration, or diagrams with written text), control of pacing (pacing was controlled by either the learner or the system), and control of sequence (sequence was controlled by either the learner or the system). A pre-test, post-test, demographic questionnaire, subjective measure of mental effort, and the Abbreviated Math Anxiety Survey were also administered. This study revealed that mathematics anxiety was significantly positively correlated with mental effort, and significantly negatively correlated with engagement, pre-test and post-test scores. Additionally, a modality x pacing interaction was observed for both high prior knowledge and low mathematics-anxious students. Under system-pacing, the modality effect was observed, and these students achieved higher far transfer scores when learning from the diagrams and narration modality condition. However, under learner-pacing, the modality effect reversed, and high prior knowledge and low mathematics-anxious students performed better on far transfer scores when learning from the diagrams and written text modality condition. Low prior knowledge, and highly mathematics-anxious students performed poorly in all treatment conditions. Additional interactions involving sequence-control, and a four-way interaction involving prior knowledge, modality, sequence-control, and pacing were also uncovered. The results from this study demonstrate that prior knowledge and mathematics anxiety have a complex relationship with the effectiveness of the format of instruction, and the design of instructional materials needs to take into account these individual differences.Thesis (Master, Education) -- Queen's University, 2008-09-25 19:38:33.9
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Lin, Yi-Chun, i 林怡均. "The Application and Reflection of Cognitive Load Theory: Optimizing the Simulation based Learning Environment through Interface Design and Cognitive Support". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/30355300515357823095.
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博士國立中央大學
學習與教學研究所
100
In view of the importance and urgency in optimizing computer simulation assisted learning, three designs including “multiple-frame” interface design, “questioning technique” cognitive support and “multiple-frame” combining “questioning technique” were proposed based on the cognitive load theory for improving computer simulation assisted learning. Two studies were conducted to examine the effects of the three designs. In addition, “additivity hypothesis of cognitive load”, which is an important concept of cognitive load theory, was reflected and revised based on the results. In the first study, a mixed method (embedded experiment model) was utilized as the research method and 140 10th-grade students participated in this study. In the second study, a single factor experiment was used as the research method and 40 undergraduates participated in this study. In both studies, the statistical concepts about “correlation” were used as the learning topic. The independent variable was different designs of computer simulation assisted learning statistics software and the dependent variables included learning time, cognitive load in learning and test phases, learning performance, and instructional efficiency. To understand the reasons for effectiveness of: (1) the “multiple-frame” interface design, (2) the “questioning technique” cognitive support, and (3) software design combining (1) and (2), eye tracker was adopted for the sake of data collection in the second study. The main results of the two studies are summarized as follows: First, the effectiveness of the “multiple-frame” interface design was not proved. The use of “multiple-frame” leaded to extraneous cognitive load and distracted the learners from the important representations of understanding the concepts about “correlation” (i.e., correlation coefficient, scatter plot, and X Y table) and the relationships of the important representations. Second, the effectiveness of the “questioning technique” cognitive support was proved. The use of “questioning technique” leaded to germane cognitive load and let learners concentrated on the important representations and the relationships of the important representations. Third, comparing to the design using “multiple-frame” and “questioning technique” individually, the design combining “multiple-frame” and “questioning technique” leaded to the worst effects. The learners were distracted from the important representations and the relationships of the important representations. Last but not the least, when learners are in the risks of cognitive overload situation, the effect resulted from the combination of two instructional designs was not equal to the additivity of the effects resulted from the two single instructional design. In addition, the additivity of cognitive load was not equal to the additivity of learning effect.
Książki na temat "Environmental load theory"
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Rastoskuev, Viktor, Vladislav Donchenko, Viktor Pitulko i Varvara Ivanova. Basics of environmental impact assessment. ru: INFRA-M Academic Publishing LLC., 2017. http://dx.doi.org/10.12737/23160.
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The analysis of the regulatory framework of environmental
environment, wildlife, and environmental safety in Russia and
abroad. Particular attention is paid to the presentation of the theory, methodology and practice
cal techniques for geo-environmental study of economic activity
level of a feasibility study, design,
construction and operation, as well as designing principles
tion and environmental protection facilities. The conceptual procedure
environmental impact assessment (EIA), environmental
risk analysis, assessment and auditing, which are the main tools
Tami environmental support planned economic activity
of Russia´s (methods, tools, and environmental assessment criteria, methods
Wild assess the intensity of anthropogenic load on the environment).
Compliant with the Federal State of Education
tional standard of the latest generation of higher education.
Recommended for students and teachers of all technical eg
boards and university education specialties. May be
also used in the study courses "Ecology", "Ecology and nature
dopolzovanie "" Environmental Protection "," Harmful substances in the environ-
environment "," Ekozaschitnaya equipment and technology "and aspiranta-
E specialty "Geoecology".
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Harry, Elizabeth, i John Sweller. Cognitive Load Theory and Patient Safety. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199366149.003.0002.
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Effective patient care depends on the ability to store and retrieve patient information and medical knowledge. All knowledge is either acquired from the environment or created de novo through trial and error. In either case, cues from the environment are filtered through working memory to attempt to guide action. Psychological principles such as resource theory and cognitive load theory suggest that humans have a limited amount of working memory that can be used to assimilate new information. When working memory is overloaded (i.e., cognitive overload), one’s attention is limited to fewer salient patient data pieces and one will naturally begin to ignore potentially crucial information. Cognitive overload can occur as a result of highly complex information, poorly organized information, distracting environments, or provider physiology. Attention to factors that lead to cognitive overload are critical in designing safe patient care systems.
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Kvint, Vladimir. STRATEGIZING OF KUZBASS REGION ECOLOGICAL DEVELOPMENT. Kemerovo State University, 2021. http://dx.doi.org/10.21603/978-5-8353-2797-3.
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The monograph «Strategizing of Kuzbass Region Ecological Development» proposes strategic
initiatives for the transformation of Kuzbass region in the environmental sphere based on the greening
of industries in the main sectors of the economy, their transition to the principles of a "green" economy,
the introduction of modern technologies in order to protect and improve the environment, preserve
natural resources and improving of Kuzbass citizens` quality of life, ensuring the development of
environmental education, as well as the recreational role of specially protected natural areas and the
development of ecological tourism.
The research is based on the theory of strategy and strategizing methodology of academician
V. L. Kvint.
A strategic analysis of global and national ecological trends and man-made loads of economic
activities on the environment of Kuzbass, as well as information from government reports, programs
and other analytical sources on the quality of atmospheric air, the state of surface and ground waters,
soils, land and forest resources, specially protected natural areas determined the choice of the most
important priorities for strategic environmental development and the adoption of effective measures
to improve the ecology of Kuzbass.
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Cleave, Rohan, i Coral Tulloch. Phasmid. CSIRO Publishing, 2015. http://dx.doi.org/10.1071/9781486301133.
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Phasmid is the amazing true story of the Lord Howe Island Phasmid, or Stick Insect. Believed to be extinct for nearly 80 years, the phasmids were rediscovered on Balls Pyramid, a volcanic outcrop 23 kilometres off the coast of Lord Howe Island, Australia. News of their unbelievable survival made headlines around the world and prompted an extraordinary conservation effort to save this remarkable invertebrate.
This wonderful tale captures the life of one of the world's most critically endangered invertebrates, from beginning life as an egg to surviving harsh environments and the hopeful return to their homeland, Lord Howe Island.
With a captivating narrative by Rohan Cleave, invertebrate zookeeper at Melbourne Zoo, and stunning watercolour illustrations by renowned artist Coral Tulloch, Phasmid is a positive story about one species' incredible survival in a time of worldwide species decline.
Phasmid is perfect for primary aged readers.
Honour Book, The CBCA Eve Pownall Award for Information Books 2016
Shortlisted for The Wilderness Society's Annual Environment Award for Children's Literature 2016
Recipient of a 2016 Whitley Award commendation for Children's Conservation Book
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Sheppard, Charles R. C., Simon K. Davy, Graham M. Pilling i Nicholas A. J. Graham. The abiotic environment. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198787341.003.0003.
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Coral reefs are largely restricted to shallow tropical seas, where water is warm, nutrient poor and well illuminated for photosynthesis and where sufficient calcium carbonate (aragonite) exists in seawater for the precipitation of coral skeletons (i.e. calcification). Extreme temperatures and salinities cause thermal and osmotic stress, while large amounts of sediment smother corals and block light. High concentrations of nutrients encourage algal growth at the expense of corals, while low seawater aragonite concentrations prevent net accretion of the reef framework. At local scales, the hydrodynamic regime influences reef growth, as corals are damaged by storms and wave surge. The typical abiotic environment in which reefs are found, and which determines reef distribution, is defined. The chapter also discusses marginal reefs, where corals live at the margins of their survival, for example in the warm, salty seas of the Persian Gulf and the relatively cold waters of Australia’s Lord Howe Island.
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Rentz, David. Guide to the Katydids of Australia. CSIRO Publishing, 2010. http://dx.doi.org/10.1071/9780643100183.
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Katydids are among the most commonly seen Australian insects. They range in size from about 5 mm to well over 90 mm and occur in many habitats all over Australia. Katydids are masters of deception, imitating twigs, bark, leaves and stems, as well as other insects. A few are brightly coloured and are distasteful to predators. They continue to be research subjects in many university curricula, where students study their behaviour, acoustical physiology and ecology.
A Guide to the Katydids of Australia explores this diverse group of insects from the family Tettigoniidae, which comprises more than 1000 species in Australia, including Norfolk and Lord Howe islands. It highlights their relationships to plants, humans and the environment, and includes colour photographs of many species.
2011 Whitley Award Commendation for Field Guide.
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van Deusen, Nancy E. “The Lord walks among the pots and pans”. University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252036637.003.0006.
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This chapter examines Christianity as a lived experience for women of African descent, both in the world and in the cloister. By the seventeenth century, thousands of free and enslaved men and women of African descent lived in monasteries and convents throughout Latin America, including the urban areas of Brazil, Peru, and Mexico. Many served as donados/donadas, legos/legas, or freilas (synonyms for religious servants). This chapter investigates the religious lives of free Afro-Peruvian women who served as donadas in the female convents of seventeenth-century Lima. In particular, it considers how donadas negotiated a hierarchically ordered environment to gain prominence as spiritual beings. It also discusses the matriarchal intimacies of convent life and the positionality of donadas relative to others within the convents as well as their ability to effectuate a spiritual life. It shows that a variety of issues motivated women of African heritage to become donadas, including the desire to ensure their freedom.
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Katsuragawa, Mario, Luiz Vianna Nonato i Francisco Luiz Vicentini Neto. Guia do oceanógrafo: Manuseio de cabos e acessórios. Brazil Publishing, 2021. http://dx.doi.org/10.31012/978-65-5861-334-3.
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Oceanography is a multidisciplinary science that deals with the physical, chemical, geological e biological aspects of the marine environment. As most of the sciences, oceanographic research relies heavily on sampling procedures, which can be rather simple, as obtaining a water sample at sea surface, or very complex, as bringing an uncontaminated sediment sample from hadal regions (up to 11,000 m deep) to the surface. Despite the sampling operation complexity, it is of primary importance the use of the adequate instrumentation, as well the expertise of the instrument operator. Ideally, the operator should have a good knowledge of the technical characteristics of the instruments themselves, as well as the correct procedures for their operation. In addition, he should be well acquainted to the ship equipment employed in the deployment, operation and retrieval of those instruments, including cables, winches and cranes. Only if these aspects are taken in account a reliable and safe operation can be attained. In this way, this guide was conceived as a basic reference for researchers in their on-board operations, although certainly being useful for a wide range of outdoor activities. It was based on the authors years of experience in field work onboard research and fishing vessels. It includes notions on nautical cables, onboard load handling equipment and hardware, basic ropework, basic net weaving and repairing and a nautical glossary.
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Layden, Timothy B. Reflection. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199351411.003.0022.
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For me every sound has its own shape or form. This sense of shape is like objects in my periphery. They move around me and change in size and structure depending on how the sounds change. The experience is more intense with more complex sounds and when the source of the sound is not visible. I wonder if it is my brain creating the visual for the sound. The shapes seem to reflect the sound: liquid sounds often create fluid bubbly shapes; sharp clanging sounds have more angular shapes like growing crystals; bass sounds are large and expanding. When there is a loud, seemingly singular sound, this can create a sense of space around me as if I were inside the shape itself. When many sounds occur at once, the shapes often combine, creating a complex structure or a texture. These shapes sometimes blend together, rather as sounds do in the environment, creating a moving landscape. These experiences are part of how I sense the world and rarely stand out as distractions. Sometimes, however, a sudden, unexpected sound will evoke a synaesthetic experience that is distracting, drawing my attention away from whatever I might be doing....
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Gerc, Krzysztof, i Bogusława Piasecka, red. Contextual Axiological Conditions of Mental Resilience and Health. Wydawnictwo Uniwersytetu Jagiellońskiego, 2020. http://dx.doi.org/10.4467/k7169.141/20.20.15535.
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The metaphor in which the accumulation of life experiences by a human being is compared to the act of packing luggage before a long, difficult and unpredictable journey is well known. All negative, painful life experiences constitute the overwhelming weight of metaphorical luggage; while positive experiences are meant to make this load lighter, and the travel – safer and more predictable. The presented metaphor indirectly describes the basic premise of the monograph, illustrating how the greatest simplification can characterize the formation of self-esteem and resilience in man, identifying them with the synergistic effect of experience (including primarily the impact of family and social environment) and biologically conditioned features. “The reviewed texts offer a lot of interesting information, based on solid empirical studies, and introduce new, relatively little-known methods of psychological research. All texts also have a practical dimension (…). In particular, they relate to the issues of resilience, autism, coping with stress and quality of life. The edited collection may be of particular interest to psychologists dealing with health issues or working in the field of clinical psychology, but also to people associated with educational and developmental psychology. It may be helpful to psychology graduates, as well as to some students of social sciences – including psychology, health sciences and, in a way, pedagogy”. dr hab. Krzysztof Mudyń, prof. Jesuit University in Kraków
Części książek na temat "Environmental load theory"
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Sweller, John, Paul Ayres i Slava Kalyuga. "Interacting with the External Environment: The Narrow Limits of Change Principle and the Environmental Organising and Linking Principle". W Cognitive Load Theory, 39–53. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-8126-4_4.
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Barr, J. M., M. N. Bremer i J. C. Baker. "The Environments of Radio-Loud Quasars". W QSO Hosts and Their Environments, 119–26. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0695-9_20.
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Leppink, Jimmie, i José Hanham. "Human Cognitive Architecture Through the Lens of Cognitive Load Theory". W Instructional Design Principles for High-Stakes Problem-Solving Environments, 9–23. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2808-4_2.
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Hardcastle, Martin J. "Extended X-Ray Emission Around Radio-Loud Quasars". W QSO Hosts and Their Environments, 127–32. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0695-9_21.
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O’Dowd, Matthew, C. Megan Urry, Riccardo Scarpa, Renato Falomo, Joseph E. Pesce i Aldo Treves. "The Nucleus-Host Galaxy Connection in Radio-Loud AGN". W QSO Hosts and Their Environments, 13–20. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0695-9_2.
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Dunlop, James S. "The Hosts Galaxies of Radio-Loud and Radio-Quiet Quasars". W QSO Hosts and Their Environments, 3–12. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0695-9_1.
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Sillanpää, A. "The Real Difference Between Radio-Loud and Radio-Quiet AGNs". W QSO Hosts and Their Environments, 59–60. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0695-9_10.
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Falomo, R., J. K. Kotilainen i A. Treves. "VLT-ISAAC Imaging of Three Radio Loud Quasars at Z ~ 1.5". W QSO Hosts and Their Environments, 343–46. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0695-9_57.
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Katole, D. N., M. B. Daigavane i P. M. Daigavane. "Implementation of Single-Phase SRF (d-q) Theory for Control Technique in DVR Restoring Voltage Sag in Sensitive Nonlinear Load". W Smart Technologies for Energy, Environment and Sustainable Development, 11–22. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-6148-7_2.
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Savard, Martine M., i Rolf T. W. Siegwolf. "Nitrogen Isotopes in Tree Rings—Challenges and Prospects". W Stable Isotopes in Tree Rings, 361–80. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_12.
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AbstractNutritive, but detrimental if at high levels, several nitrogen (N) forms involved in air and soil biogeochemical reactions constitute the N load trees assimilate. Although a large body of literature describes series of tree-ring N isotopes (δ15N) as archival systems for environmental changes, several questions relative to the isotopic integrity and reproducibility of trends still linger in the dendroisotopist community. This chapter reviews the fundamentals of forest N cycling and examines trees as N receptors in their very position, at the interface between the atmosphere and pedosphere. The related scrutiny of intrinsic and extrinsic mechanisms regulating isotopic changes also underlines flaws and forces of tree-ring δ15N series as environmental indicators.
Streszczenia konferencji na temat "Environmental load theory"
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Ashirin, M. F. Zainal, i A. F. Mohamad Ayob. "Dynamic responses of moored installation vessel during lifting operation due to environmental load". W 2017 IEEE 7th International Conference on Underwater System Technology: Theory and Applications (USYS). IEEE, 2017. http://dx.doi.org/10.1109/usys.2017.8309440.
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Gong, Wei. "Hydrodynamic and Aerodynamic Loads on the Behaviour of Offshore Wind Farm". W ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49490.
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Renewable energy provides a solution for complex current and future social and environmental problems whereas offshore industry has a large potential for providing renewable energy for future. Currently, offshore technology making use of wind for energy generation purpose becomes a hot spot with highly advanced research and development going on on one side and complex and critical problems present and difficult to solve on the other. This paper is trying to study problems related to the quantification of the hydrodynamic and aerodynamic loads for the design of offshore wind turbine support structures in the offshore wind farm. Both the hydrodynamic and aerodynamic conditions in the offshore site are extremely complex resulting in the difficulty of reasonable determination for the external loads on the wind turbine support structures. However, due to the increasing global demands for future energy solution, the design, analysis and optimization of offshore wind turbine is nevertheless an important issue. The paper first gives an introduction of the offshore wind farm and the complexity of the offshore environment. Wave load is explored with introduction of existing wave load models, comparison of their characteristics while the focus is placed on the nonlinear wave load by means of the Stokes higher order wave theory. Properties of a single regular wave based on methods of linear wave theory and Stokes higher order wave theory are compared which lead to differences in the results of wave load models when these two different methods are used. Wind load model is introduced briefly, followed by the introduction of current methods for determination or approximation of combined wave and wind load and also recommendations for practice. Park effect of the wind load and wave load is also introduced at limited depth in the latter stage as a direction for future research. Conclusion and recommendations based on all the above are therefore given at the last section of the paper.
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Fitzwater, LeRoy M., C. Allin Cornell i Paul S. Veers. "Using Environmental Contours to Predict Extreme Events on Wind Turbines". W ASME 2003 Wind Energy Symposium. ASMEDC, 2003. http://dx.doi.org/10.1115/wind2003-865.
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This paper presents and explores estimating design loads on wind turbines using the environmental contour method. Contours promise to provide both practical reliability estimation and valuable information about the combination of joint environmental variable values, e.g. wind speed and turbulence, most critical to each specific wind turbine. We present the background of the development of environmental contours as applied to wind energy systems, and apply this theory, in three examples, to develop contours based either (1) on design code description of environmental conditions, or (2) on measured data for a site-specific application. The site-specific case is used for both stall and pitch controlled turbine examples. From these contours, and a functional description of the short-term response of the turbine, implicit FORM estimates are made for the turbine response; these estimates are compared with results obtained from numerical integration of the short-term response of the turbine over the joint distribution of wind speed and turbulence. We find that the environmental contour method provides reasonable estimates of the expected extreme load, compared with the full integration method.
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Li, Yan, Zheng Liu, Yougang Tang, Xiyang Zhu i Ruoyu Zhang. "Dynamic Response of a Conceptual Designed Articulated Offshore Wind Turbine". W ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95635.
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Abstract Focus on the 75-meter-depth offshore area, an articulated buoy is proposed for supporting NREL 5 MW offshore wind turbine. Based on the optimization, the main parameters are set for better hydro performance and less environmental loads. According to the quasi-static approach, the intact stability was examined. Then, an in-house code was programmed to simulate the dynamic response of the articulated offshore wind turbine. The aerodynamic load on rotating blades and the wind pressure load on tower are calculated based on the blade element momentum theory and the empirical formula, respectively. The hydrodynamic performance is simulated by the 3-D potential flow theory. The motions of platform, the loads on the articulated hinge and the power generation performance are documented in different cases. According to the simulations, the articulated offshore wind turbine shows good hydrodynamic performance under operation conditions.
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Feng, Weizhong. "Generalized Regeneration Theory and its Energy Saving and Emission Reduction Effects on Coal-Fired Power Generation". W ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59166.
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Concerns related to global warming and environmental pollution concerns have pressured coal-fired power plants to improve efficiency and reduce emissions. However, the conventional efficiency improvement methods — increasing steam pressure and temperature and reducing condenser pressure are limited by material technology and the temperature of the available cooling medium. The next step for increasing efficiency would be to add additional reheat or regenerative cycles, but this is not feasible for existing plants. In addition, as the share of renewable energy and the grid’s demands on the coal-fired power plants increases, China’s coal-fired units are faced with more and tougher challenges, including large peak-valley gaps, frequent startups and shutdowns and cost pressures. As a result, the boiler combustion efficiency decreases and incidents such as furnace explosions, aggravation and collapsing of slag and burning of facilities located downstream of the economizer become more frequent. To address these problems, the generalized regeneration theory has been proposed and a series of related technologies have been developed, providing a new approach for not only improving the efficiency of coal-fired power plants, but also resulted in boiler operation that is cleaner and safer. These technologies which include anew boiler startup technology, the high efficiency combustion and low emission technology under low load and the low oxygen, and a low NOx and high efficiency combustion technology under high load have been implemented successfully in the Shanghai Waigaoqiao No. 3 power plant. By improving the utilization of turbine extraction and reducing the exhaust loss, these innovative technologies greatly improve the environmental performance, efficiency and safety of the units in various operating conditions. In addition, improvements have been made in the boilers ability to adapt to changing coal supplies, particularly for coal with high slagging tendencies and high moisture content.
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Kosleck, Sascha, i Florian Sprenger. "Maximum Wave Load Cycles on Submerged Rotating Tidal Energy Turbines: Identification of Worst Case Scenarios". W ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61569.
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In recent decades, significant research and development has been invested in techniques that harvest renewable energy from an ocean environment. Starting from offshore wind energy we also see developments in devices that extract energy from sources such as waves and tides. Although a lot can be learned by transferring existing on- and offshore technology, a multitude of new challenges arouse. The offshore wind industry for example has struggled with wave induced loads on their wind turbine foundations structures, which resulted in intense nacelle and rotor vibrations. These vibrations have a significant impact a turbine’s lifetime. The specific problem of oscillating wave loads worsens for tidal energy turbines as no longer only the foundation but also the rotor itself is submerged and directly exposed to wave induced forces. Therefore, the best possible determination of these loads is a key prerequisite for any holistic vibration and fatigue analysis. During operation, the turbine rotor will, depending on the actual tidal current velocity, rotate at different speeds whilst the waves propagate over it. The number of ratios between wave period Tw and rotational period of the rotor Tr is therefore infinite. This raises the question what load changes a revolving rotor blade experiences and which combination of Tw/Tr and wave encounter angle will generate the maximum loads per cycle. This study presents a comprehensive, general approach to identify maximum possible wave induced forces and moments on stationary and turning rotor blades, for any turbine design, position in the water column and orientation in the wave field. The procedure is exemplified for a generic 3-bladed horizontal axis turbine which is fixed to the seabed. The approach identifies loads depending on wave period and height, the period of rotor rotation and the wave encounter angle, utilising diffraction theory. Forces and moments are firstly calculated in a global coordinate system and subsequently transferred into a blade fixed coordinate system. This allows for an examination of the load changes as the blades rotate about the turbine axis. Thus, the worst-case scenarios in terms of load changes for each combination of wave parameters can be identified. Those maximum load cycle events are then combined to transfer functions, for loads and moments respectively. Transfer functions such as these will later allow for a quick identification of maximum load changes and cycle periods, depending on any given environmental condition. This information will help identifying structural loads and immanent fatigue and vibration issues during the actual turbine design process.
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Detlefsen, Ole, Carl Reiner i Moustafa Abdel-Maksoud. "A Reliable Multilevel Method for Simulation-Based Load Determination on Deck Cell Guides". W ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-78713.
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Abstract The loss of containers at sea endangers ships and crew and causes environmental pollution. Within the Joint Research Project RetroLadung, weight-optimized container cell guides with integrated motion sensors and AI-based decision support (DSS) are developed as a technical solution for increased safety in marine transportation. Therefore, the authors developed an efficient simulation-based approach to determine the motion-induced loads acting on the containers. For the validation of the applied numerical methods, model tests have been performed in the towing tank operated by the Institute for Fluid Dynamics and Ship Theory (FDS). The paper describes the applied numerical methods for the load determination and first preliminary results from the ongoing experimental validation work. Finally, the application of the developed method is demonstrated by calculating the loads for the structural design and optimization of the cell guides for a towed container barge operated at the US east coast.
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Li, Linbin, Ping Li i Yuan Liu. "How We Determine the Design Environmental Conditions and How They Impact the Structural Reliabilities?" W ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23198.
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This paper is based on the JIP study for the oceanographic hindcast and environmental load statistics of fixed steel structures at South China Sea under tropical cyclone conditions. It focuses on the sensitivity and comparison studies by exploring the degrees and reasons of variability that may occur in determination of design environmental conditions resulting from the selection of the design standards and approaches. The bias and efficiency in extreme values prediction are examined with respect to modeling uncertainty and statistical uncertainty. The long term distributions of maximum wave height as well as the associated wave period conditional on the design wave height are derived following the storm event based method. The approaches for combing wave, current and wind to define the design conditions and the associated biases on design load are investigated. Second order random and spreading wave theory is adopted to estimate the extreme wave crest height distributions. The extreme water level issue is addressed and recommendations are given for setting the deck elevation to achieve the explicit wave-in-deck probabilities. The studies are carried out by applying a dataset of a grid point containing 182 typhoons spanning 40 continuous years to demonstrate the analytical procedures in an understandable fashion. The results of this paper should lead to improvements in prediction of the environmental conditions for design of new-built structures to attain their target safety levels, as well as for assessment of existing structures to demonstrate their fitness-for-purpose.
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Ren, Huilong, Chenfeng Li, Hui Li i Guoqing Feng. "Fatigue Strength Assessment of Aged Floating Production System". W ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57695.
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Fatigue is one of the most frequent causes of failure for offshore structures subjected to environmental loads, especially aged structures. An effective method for calculating the fatigue damage of aged platform under regular wave is presented. Three-dimensional source distribution theory in the frequency domain is used to calculate fatigue load of FPS in regular wave. The hot spot stress in the welded knuckles is calculated on the basis of a detailed finite element model. Based on the S-N curve and the Miner linear accumulative damage theory, the calculation process of fatigue damage of components was simplified. The calculated results show that this computing method is convenient and accurate. It is suitable for engineering application.
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Kanaga Karuppiah, K. S., Angela L. Bruck i Sriram Sundararajan. "Evaluation of Friction Behavior and Contact Area Dependence at the Micro and Nanoscales". W ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44216.
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In this work, we have compared the friction behavior of two different materials (a) mica and (b) ultra-high molecular weight polyethylene (UHMWPE) at two length scales. The friction experiments were carried out at the nanoscale with an atomic force microscope (AFM) and at the microscale, with a custom-built microtribometer. The material interface (Si3N4 probe) and the environmental conditions (RH < 10%) were kept the same at both the scales. The friction data obtained were analyzed for dependence on normal load or contact area, based on which, a coefficient of friction has been reported or an appropriate contact mechanics theory was applied and an interfacial shear strength value was calculated for the material pair. Friction between a silicon nitride and UHMWPE interface resulted in contact area dependence at both the length scales, for the applied load ranges of our experiment. Friction between silicon nitride and mica at the nanoscale showed an initial nonlinearity and then exhibited damage and linearity with normal load beyond certain loads. At the microscale, the mica-silicon nitride interface resulted in a linear friction behavior.
Raporty organizacyjne na temat "Environmental load theory"
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Regan, Jack, i Robin Zevotek. Study of the Fire Service Training Environment: Safety and Fidelity in Concrete Live Fire Training Buildings. UL Firefighter Safety Research Institute, lipiec 2018. http://dx.doi.org/10.54206/102376/wxtw8877.
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The goal of fire service training is to prepare students for the conditions and challenges that they face on the fireground. Among the challenges that firefighters routinely face on the fireground are ventilation-controlled fires. The hazard of these fires has been highlighted by several line-of-duty deaths and injuries in which a failure to understand the fire dynamics produced by these fires has been a contributing factor. The synthetic fuels that commonly fill contemporary homes tend to result in ventilation-controlled conditions. While synthetic fuels are common on the residential fireground, the fuels that firefighters use for fire training are more often representative of natural, wood-based fuels. In order to better understand the fire dynamics of these training fires, a series of experiments was conducted in a concrete live fire training building in an effort to evaluate the fidelity and safety of two training fuels, pallets and OSB, and compare the fire dynamics created by these fuels to those created by a fuel load representative of a living room set with furniture items with a synthetic components. Additionally, the effects of the concrete live fire training building on the fire dynamics were examined. The two training fuel loads were composed of wooden pallets and straw, and pallets, straw, and oriented strand board (OSB). The results indicated that the high leakage area of the concrete live fire training building relative to the fuel load prevented the training fuel packages from becoming ventilation-controlled and prevented the furniture package from entering a state of oxygen-depleted decay. The furniture experiments progressed to flashover once ventilation was provided. Under the conditions tested, the wood based fuels, combined with the construction features of this concrete live fire training building, limited the ability to teach ventilation-controlled fire behavior and the associated firefighting techniques. Additionally, it was shown that the potential for thermal injury to firefighters participating in a training evolution existed well below thresholds where firefighter PPE would be damaged.
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Bradford, Kent, Haim Nerson, Gregory Wellbaum i Menahem Edelstein. Environmental, Developmental and Physiological Determinants of Curcurbit Seed Quality. United States Department of Agriculture, październik 1998. http://dx.doi.org/10.32747/1998.7695837.bard.
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Environmental, developmental, physiological and biochemical determinants of cucurbit seed quality were investigated in field and laboratory experiments. The major factor influencing seed quality is seed maturity at harvest, with both immature and overmature seeds exhibiting reduced quality. Planting density and fruit load per plant can be manipulated to maximize seed yield per unit area without adversely affecting seed quality. Seeds harvested at optimal maturity will have the greatest germination vigor and will maintain quality longer during storage. Seed priming can improve germination rates and uniformity, but can reduce storage life. Tissues enclosing the embryo (the endosperm envelope and seed coat) are involved in regulating germination. The seed coat (testa) may restrict oxygen diffusion to the embryo in some muskmelon genotypes. Weakening of the endosperm envelope is associated with radicle emergence. Callose deposition in the endosperm envelope results in semipermeability. Defense proteins such as chitinase are also present in the endosperm. Numerous genes were identified that are expressed specifically in association with germination, but their functions are yet to be elucidated. These studies have provided guidelines for producing and harvesting cucurbit seeds for maximum yield and quality and have identified physiological and biochemical processes contributing to seed germination vigor.
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Stakes, Keith, i Joseph Willi. Study of the Fire Service Training Environment: Safety, Fidelity, and Exposure -- Acquired Structures. UL Firefighter Safety Research Institute, marzec 2019. http://dx.doi.org/10.54206/102376/ceci9490.
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Previous FSRI led research projects have focused on examining the fire environment with regards to current building construction methods, synthetic fuel loading, and best-practices in firefighting strategies and tactics. More than 50 experiments have been previously conducted utilizing furniture to produce vent-limited fire conditions, replicating the residential fire environment, and studying the methods of horizontal ventilation, vertical ventilation, and positive pressure attack. Tactical considerations generated from the research are intended to provide fire departments with information to evaluate their standard operating procedures and make improvements, if necessary, to increase the safety and effectiveness of firefighting crews. Unfortunately, there still exists a long standing disconnect between live-fire training and the fireground as evident by continued line of duty injury and death investigations that point directly to a lack of realistic yet safe training, which highlights a continued misunderstanding of fire dynamics within structures. The main objective of the Study of the Fire Service Training Environment: Safety, Fidelity, and Exposure is to evaluate training methods and fuel packages in several different structures commonly used across the fire service to provide and highlight considerations to increase both safety and fidelity. This report is focused on the evaluation of live-fire training in acquired structures. A full scale structure was constructed using a similar floor plan as in the research projects for horizontal ventilation, vertical ventilation, and positive pressure attack to provide a comparison between the modern fire environment and the training ground. The structure was instrumented which allowed for the quantification of fire behavior, the impact of various ventilation tactics, and provided the ability to directly compare these experiments with the previous research. Twelve full scale fire experiments were conducted within the test structure using two common training fuel packages: 1) pallets, and 2) pallets and oriented strand board (OSB). To compare the training fuels to modern furnishings, the experiments conducted were designed to replicate both fire and ventilation location as well as event timing to the previous research. Horizontal ventilation, vertical ventilation, and positive pressure attack methods were tested, examining the proximity of the vent location to the fire (near vs. far). Each ventilation configuration in this series was tested twice with one of the two training fuel loads. The quantification of the differences between modern furnishings and wood-based training fuel loads and the impact of different ventilation tactics is documented through a detailed comparison to the tactical fireground considerations from the previous research studies. The experiments were compared to identify how the type of fuel used in acquired structures impacts the safety and fidelity of live-fire training. The comparisons in this report characterized initial fire growth, the propensity for the fire to become ventilation limited, the fires response to ventilation, and peak thermal exposure to students and instructors. Comparisons examined components of both functional and physical fidelity. Video footage was used to assess the visual cues, a component of the fire environment that is often difficult to replicate in training due to fuel load restrictions. The thermal environment within the structure was compared between fuel packages with regards to the potential tenability for both students and instructors.
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DeAnna, Dixon, i Hodo Wayne. Finite element analysis of quoin block deterioration and load transfer mechanisms in miter gates : pintle and pintle connections. Engineer Research and Development Center (U.S.), czerwiec 2021. http://dx.doi.org/10.21079/11681/40842.
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The U.S. Army Corps of Engineers (USACE) currently operates and maintains approximately 193 commercially active lock sites with 239 locks and dams spanning nearly 12,000 miles. These networks of water channels are used to transport 600 million tons of domestic cargo, generating $405 billion in revenue annually. Nearly 60% of these structures in operation are over 50 years old and have reached design life. A failure of the miter gates could result in a major negative impact on the economy and on the ability to maintain flood control. Administrators need recommendations to better prioritize maintenance and repair of the USACE miter gates. This work investigated the influence of miter gate’s quoin block degradation on load transfer to the pintle and/or pintle connections. Results of finite element analysis are reported for the quoin block degradation simulated levels of 0%, 25%, 50%, and 75%. The parametric study shows the overstressed regions are the pintle neck and bolt-hole regions. To improve pintle designs so they may better mitigate detrimental environmental based deterioration effects, this work recommends (1) increasing the thickness of the bolt-hole connection region and (2) adding ribbing reinforcement around the neck area of the pintle.
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Fuchs, Marcel, Ishaiah Segal, Ehude Dayan i K. Jordan. Improving Greenhouse Microclimate Control with the Help of Plant Temperature Measurements. United States Department of Agriculture, maj 1995. http://dx.doi.org/10.32747/1995.7604930.bard.
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A model of the energy balance of a transpiring crop in a greenhouse was developed in a format suitable for use in climate control algorithms aimed at dissipating excess heat during the warm periods. The model's parameters use external climatic variables as input. It incorporates radiation and convective transfer functions related to the operation of control devices like shading screens, vents, fans and enhanced evaporative cooling devices. The model identified the leaf boundary-layer resistance and the leaf stomatal and cuticular resistance as critical parameters regulating the temperature of the foliage. Special experiments evaluated these variables and established their relation to environmental factors. The research established that for heat load conditions in Mediterranean and arid climates transpiring crops maintained their foliage temperature within the range allowing high productivity. Results specify that a water supply ensuring minimum leaf resistance to remain below 100 s m-1, and a ventilation rate of 30 air exchanges per hour, are the conditions needed to achieve self cooling. Two vegetable crops, tomato and sweet pepper fulfilled maintained their leaf resistance within the prescribed range at maturity, i.e., during the critical warm season. The research evaluates the effects of additional cooling obtained from wet pad systems and spray wetting of foliage.
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Cahaner, Avigdor, Sacit F. Bilgili, Orna Halevy, Roger J. Lien i Kellye S. Joiner. effects of enhanced hypertrophy, reduced oxygen supply and heat load on breast meat yield and quality in broilers. United States Department of Agriculture, listopad 2014. http://dx.doi.org/10.32747/2014.7699855.bard.
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Original objectivesThe objectives of this project were to evaluate the growth performance, meat yield and quality attributes of broiler strains widely differing in their genetic potential under normal temperature vs. warm temperature (short and long-term) conditions. Strain differences in breast muscle accretion rate, metabolic responses under heat load and, gross and histopathological changes in breast muscle under thermal load was also to be characterized. BackgroundTremendous genetic progress has been made in broiler chicken growth rate and meat yield since the 1950s. Higher growth rate is driven by higher rates of feed intake and metabolism, resulting in elevated internal heat production. Hot rearing conditions negatively affect broiler growth by hindering dissipation of heat and may lead to a lethal elevation in body temperature. To avoid heat-induced mortality, broilers reduce feed intake, leading to depressed growth rate, lower weight gain, reduce breast meat yield and quality. Thus, the genetic potential of contemporary commercial broilers (CCB) is not fully expressed under hot conditions. Major conclusions, solutions, and achievementsResearch conducted in Israel focused on three broiler strains – CCB, Featherless, Feathered sibs (i.e., sharing similar genetic background). Complimentary research trials conducted at Auburn utilized CCB (Cobb 500, Cobb 700, Ross 308, Ross 708), contrasting their performance to slow growing strains. Warm rearing conditions consistently reduced feed intake, growth rate, feed efficiency, body weight uniformity and breast muscle yield, especially pronounced with CCB and magnified with age. Breast meat quality was also negatively affected, as measured by higher drip loss and paler meat color. Exposure to continuous or short-term heat stress induced respiratory alkalosis. Breast muscle histomorphometrics confirmed enhanced myofiber hypertrophy in CCB. Featherless broilers exhibited a significant increase in blood-vessel density under warm conditions. Rapid growth and muscle accretion rate was correlated to various myopathies (white striping, woody and necrotic) as well as to increases in plasma creatinekinase levels. Whether the trigger(s) of muscle damage is loss of cellular membrane integrity due to oxidative damage or tissue lactate accumulation, or to loss of inter-compartmental cation homeostasis is yet to be determined. Based on genome-wide single-nucleotide polymorphism array genotyping, identification of the gene with the recessive mutation Scaleless (sc) facilitated the development a dCAPS assay to discriminate between sc carrier (sc/+) and non-carrier (+/+) individuals. ImplicationsThis project confirmed that featherless broiler strains grow efficiently with high yield and quality of breast meat, even under warm rearing conditions that significantly depress the overall performance of CCB. Therefore, broiler meat production in hot regions and climates can be substantially improved by introducing the featherless gene into contemporary commercial broiler stocks. This approach has become more feasible with the development of dCAPS assay. A novel modification of the PCR protocol (using whole blood samples instead of extracted DNA) may contribute to the efficient development of commercial featherless broiler strains. Such strains will allow expansion of the broiler meat production in developing countries in warm climates, where energy intensive environmental control of rearing facilities are not economical and easily achievable.
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Seginer, Ido, Daniel H. Willits, Michael Raviv i Mary M. Peet. Transpirational Cooling of Greenhouse Crops. United States Department of Agriculture, marzec 2000. http://dx.doi.org/10.32747/2000.7573072.bard.
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Background Transplanting vegetable seedlings to final spacing in the greenhouse is common practice. At the time of transplanting, the transpiring leaf area is a small fraction of the ground area and its cooling effect is rather limited. A preliminary modeling study suggested that if water supply from root to canopy is not limiting, a sparse crop could maintain about the same canopy temperature as a mature crop, at the expense of a considerably higher transpiration flux per leaf (and root) area. The objectives of this project were (1) to test the predictions of the model, (2) to select suitable cooling methods, and (3) to compare the drought resistance of differently prepared seedlings. Procedure Plants were grown in several configurations in high heat load environments, which were moderated by various environmental control methods. The difference between the three experimental locations was mainly in terms of scale, age of plants, and environmental control. Young potted plants were tested for a few days in small growth chambers at Technion and Newe Ya'ar. At NCSU, tomato plants of different ages and planting densities were compared over a whole growing season under conditions similar to commercial greenhouses. Results Effect of spacing: Densely spaced plants transpired less per plant and more per unit ground area than sparsely spaced plants. The canopy temperature of the densely spaced plants was lower. Air temperature was lower and humidity higher in the compartments with the densely spaced plants. The difference between species is mainly in the canopy-to-air Bowen ratio, which is positive for pepper and negative for tomato. Effect of cooling methods: Ventilation and evaporative pad cooling were found to be effective and synergitic. Air mixing turned out to be very ineffective, indicating that the canopy-to-air transfer coefficient is not the limiting factor in the ventilation process. Shading and misting, both affecting the leaf temperature directly, proved to be very effective canopy cooling methods. However, in view of their side effects, they should only be considered as emergency measures. On-line measures of stress: Chlorophyll fluorescence was shown to accurately predict photosynthesis. This is potentially useful as a rapid, non-contact way of assessing canopy heat stress. Normalized canopy temperature and transpiration rate were shown to correlate with water stress. Drought resistance of seedlings: Comparison between normal seedlings and partially defoliated ones, all subjected to prolonged drought, indicated that removing about half of the lowermost leaves prior to transplanting, may facilitate adjustment to the more stressful conditions in the greenhouse. Implications The results of this experimental study may lead to: (1) An improved model for a sparse canopy in a greenhouse. (2) A better ventilation design procedure utilizing improved estimates of the evaporation coefficient for different species and plant configurations. (3) A test for the stress resistance of transplants.
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Willi, Joseph, Keith Stakes, Jack Regan i Robin Zevotek. Evaluation of Ventilation-Controlled Fires in L-Shaped Training Props. UL's Firefighter Safety Research Institute, październik 2016. http://dx.doi.org/10.54206/102376/mijj9867.
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Investigations of recent firefighter line of duty deaths caused by rapid fire progression have highlighted a deficiency in firefighters’ understanding of how certain tactics affect the fire dynamics of ventilation-controlled fires. Many fires are in a ventilation-limited, decay state by the time firefighters arrive at the scene, meaning that introducing additional ventilation to the environment has the potential to cause rapid and intense fire growth. To more effectively teach firefighters about the potential effects of ventilation on a compartment fire, ventilation-controlled fires should be gener- ated during training. Safely creating such fires while maintaining compliance with NFPA 1403: Standard on Live-Fire Training Evolutions allows instructors to educate students on this important principle of fire dynamics in the training environment. Structures utilized for live-fire training have evolved from typical concrete burn buildings to now include smaller purpose-built props, like those constructed from steel shipping containers or wood and gypsum board. Such props have been embraced by organizations due to their cost-effectiveness and potential to improve fire behavior training. Obtaining a thorough understanding of the capa- bilities and limitations of such props is critical for instructors to convey accurate messages during training and properly prepare firefighters for scenarios they’ll encounter in the field. Experiments were conducted to quantify the fire environment in L-shaped props with different wall constructions. One prop had an interior wall lining of gypsum board over wood studs and fiberglass insulation. The two other props were constructed from metal shipping containers with corrugated steel walls; one had ceilings and walls comprised solely of the corrugated steel, while the other had ceilings and walls comprised of rolled steel sheeting over mineral wool insulation with the corrugated steel wall as its backing. Three fuel packages were compared between the props: one contained furnishings mainly composed of synthetic materials and foam plastics; another contained wooden pallets and straw; and the third contained wooden pallets, straw, and oriented strand board (OSB). A stochastic approach was used to compare data between replicate tests and quantify the repeatability of the different props and fuel packages, all of which were deemed sufficiently repeatable. Comparisons of data between the three props revealed that thermal conditions between experiments in the two metal props were indistinguishable, suggesting that the additional layer of insulation did not significantly alter the fire environment. Additionally, thermal conditions in the gypsum-lined prop were more severe than those in the metal props. The effects of ventilation changes on fire conditions were also analyzed across various prop and fuel load combinations. Lastly, the response of the thermal environment in each prop during interior suppression was evaluated, and the results implied that the thermal exposure to the firefighter was more severe in the metal props than the gypsum prop for a brief period following the start of suppression.
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Singh, Niranjan. A Method of Sound Wave Diffusion in Motor Vehicle Exhaust Systems. Unitec ePress, kwiecień 2017. http://dx.doi.org/10.34074/ocds.072.
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It is common practice among young vehicle owners to modify the exhaust system of their vehicle to reduce exhaust backpressure with the perception that the output power increases. In the process of backpressure reduction, the output noise (Whakapau) of the vehicle also increases correspondingly. The conflict of interest that arises from modified vehicle exhaust systems and the general public is well publicised. This prototype was designed to meet the demands of exhaust back pressure reduction while at the same time mitigate the sound output of the vehicle. The design involves lining a cylindrical pipe with common glass marbles which is normally used for playing. The marbles are made of a sustainable material as it does not erode when exposed to exhaust gases and it is easily recycled. The prototype muffler is much smaller in size when compared to conventional mufflers. All tests were done in a simulated controlled environment and data collated using approved New Zealand Transport Agency testing regime. It has to be noted that the test focus was noise mitigation and not comprehensive engine performance testing. The results of the test prove a reduction of sound levels, however more testing needs to be undertaken with varying annulus depth, marble sizes and arrangements and engine loads.
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Quinn, Meghan. Geotechnical effects on fiber optic distributed acoustic sensing performance. Engineer Research and Development Center (U.S.), lipiec 2021. http://dx.doi.org/10.21079/11681/41325.
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Distributed Acoustic Sensing (DAS) is a fiber optic sensing system that is used for vibration monitoring. At a minimum, DAS is composed of a fiber optic cable and an optic analyzer called an interrogator. The oil and gas industry has used DAS for over a decade to monitor infrastructure such as pipelines for leaks, and in recent years changes in DAS performance over time have been observed for DAS arrays that are buried in the ground. This dissertation investigates the effect that soil type, soil temperature, soil moisture, time in-situ, and vehicle loading have on DAS performance for fiber optic cables buried in soil. This was accomplished through a field testing program involving two newly installed DAS arrays. For the first installation, a new portion of DAS array was added to an existing DAS array installed a decade prior. The new portion of the DAS array was installed in four different soil types: native fill, sand, gravel, and an excavatable flowable fill. Soil moisture and temperature sensors were buried adjacent to the fiber optic cable to monitor seasonal environmental changes over time. Periodic impact testing was performed at set locations along the DAS array for over one year. A second, temporary DAS array was installed to test the effect of vehicle loading on DAS performance. Signal to Noise Ratio (SNR) of the DAS response was used for all the tests to evaluate the system performance. The results of the impact testing program indicated that the portions of the array in gravel performed more consistently over time. Changes in soil moisture or soil temperature did not appear to affect DAS performance. The results also indicated that time DAS performance does change somewhat over time. Performance variance increased in new portions of array in all material types through time. The SNR in portions of the DAS array in native silty sand material dropped slightly, while the SNR in portions of the array in sand fill and flowable fill material decreased significantly over time. This significant change in performance occurred while testing halted from March 2020 to August 2020 due to the Covid-19 pandemic. These significant changes in performance were observed in the new portion of test bed, while the performance of the prior installation remained consistent. It may be that, after some time in-situ, SNR in a DAS array will reach a steady state. Though it is unfortunate that testing was on pause while changes in DAS performance developed, the observed changes emphasize the potential of DAS to be used for infrastructure change-detection monitoring. In the temporary test bed, increasing vehicle loads were observed to increase DAS performance, although there was considerable variability in the measured SNR. The significant variation in DAS response is likely due to various industrial activities on-site and some disturbance to the array while on-boarding and off-boarding vehicles. The results of this experiment indicated that the presence of load on less than 10% of an array channel length may improve DAS performance. Overall, this dissertation provides guidance that can help inform the civil engineering community with respect to installation design recommendations related to DAS used for infrastructure monitoring.