Littérature scientifique sur le sujet « Effective Internal Variable method »
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Articles de revues sur le sujet "Effective Internal Variable method"
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Sun, Xinchao, Lianyu Zhao et Zhenzhong Liu. « A model reference adaptive variable impedance control method for robot ». MATEC Web of Conferences 336 (2021) : 03005. http://dx.doi.org/10.1051/matecconf/202133603005.
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As a simple and effective force tracking control method, impedance control is widely used in robot contact operations. The internal control parameters of traditional impedance control are constant and cannot be corrected in real time, which will lead to instability of control system or large force tracking error. Therefore, it is difficult to be applied to the occasions requiring higher force accuracy, such as robotic medical surgery, robotic space operation and so on. To solve this problem, this paper proposes a model reference adaptive variable impedance control method, which can realize force tracking control by adjusting internal impedance control parameters in real time and generating a reference trajectory at the same time. The simulation experiment proves that compared with the traditional impedance control method, this method has faster force tracking speed and smaller force tracking error. It is a better force tracking control method.
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Huang, Xi, Huang Huang et Zhishen Wu. « Development of a Variable-Frequency Hammering Method Using Acoustic Features for Damage-Type Identification ». Applied Sciences 13, no 3 (19 janvier 2023) : 1329. http://dx.doi.org/10.3390/app13031329.
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Hammer testing, a nondestructive testing method, has been demonstrated to provide information on structural damage. One of the biggest challenges with this testing method is the simultaneous identification of surface, internal, and composite damage (consisting of both surface and internal damage) in a complex environment, such as post-disaster. A method of identification based on variable-frequency hammering is proposed to solve this problem. The importance and feasibility of using variable-frequency impact hammers and the generated acoustic data to identify multiple types of damage in concrete structures are presented. First, a type of variable-frequency hammering acoustic feature was generated using acoustic feature extraction and selection based on the acoustic data obtained from variable-frequency hammering. Second, a damage recognition model was established using a support vector machine to identify four types of damage occurring simultaneously in the same concrete member specimens, including a type of composite damage with two types of damage occurring simultaneously within 20 mm. Finally, the feasibility of this variable-frequency hammering method was verified experimentally. This method exhibited good performance, with an accuracy of 97.8%; moreover, the method ensures that the feature dimensionality remains unchanged while increasing the effective information of the data.
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Babajanov, Bazar, et Fakhriddin Abdikarimov. « New Soliton Solutions of the Burgers Equation with Additional Time-dependent Variable Coefficient ». WSEAS TRANSACTIONS ON FLUID MECHANICS 19 (14 février 2024) : 59–63. http://dx.doi.org/10.37394/232013.2024.19.6.
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In this article, we use the functional variational method to solve the Burgers equation with an additional time-dependent variable coefficient. The main advantage of the proposed method over other methods is that it allows to obtain more new solutions of the equation. Among the solutions obtained, new soliton solutions should be noted, which are of great importance for revealing the internal mechanism of physical phenomena. Three-dimensional graphs of solutions are constructed using the mathematical program Matlab. For a better understanding of the physical properties of some of the resulting solutions, their graphical representations are shown. This method is effective for finding exact solutions to many other similar wave equations.
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Pierart, Fabian G., Matias Rubilar et Jaime Rohten. « Experimental Validation of Damping Adjustment Method with Generator Parameter Study for Wave Energy Conversion ». Energies 16, no 14 (11 juillet 2023) : 5298. http://dx.doi.org/10.3390/en16145298.
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Effective control strategies are essential for optimizing wave energy production. While theoretical studies have explored various control approaches, experimental validation of these methods remains limited. This study proposes a damping adjustment method as a means to enable the experimental application of resistive control in wave energy systems. The system’s damping is adjusted through a variable electrical resistance coupled to the generator. A mathematical model is developed to capture the interaction between the wave energy converter, generator, and variable resistance. Experimental validation demonstrates a good fit between the experimental results and the mathematical model. Four different DC machines acting as generators are tested to evaluate the influence of the model’s parameters on control capability. Results indicate that DC machines with less internal resistance allow a wider range of damping and power adjustment by using external resistance. The proposed method shows promising results, emphasizing the significance of the DC machine parameters in achieving effective control over system variables. These findings contribute to the development of efficient and reliable control strategies for enhancing wave energy production at small scales.
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Jiang, Angfeng, Deyuan Deng, Wei Dai, Xiuwen You et Hanwen Lu. « Out-Plane Buckling of Arches with Variable Cross-Section ». Buildings 13, no 11 (13 novembre 2023) : 2838. http://dx.doi.org/10.3390/buildings13112838.
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The variable cross-section arch is widely used in practical engineering because of its beautiful arc and excellent mechanical properties. However, there is still no systematic and comprehensive study on the out-plane buckling of variable cross-section arches. In view of this, this paper is focused on the elastic analytical research of out-plane buckling of arches with variable cross-sections under a uniformly distributed radial local load. The pre-buckling and out-plane buckling behavior of a variable cross-sectional arch under an external load is quite different from that of an arch with a uniform cross-section. Castigliano’s second theorem is used to establish pre-buckling force method equilibrium equations for variable cross-sectional arches under a uniformly distributed radial local load, and corresponding analytical solutions of normal stress, axial compression, and the bending moments are obtained. Based on the energy method and the Ritz method, analytical solutions of the critical load for the elastic out-plane buckling of arches with variable cross-sections are derived. Comparisons with ANSYS results indicated that the analytical solutions are able to accurately predict the pre-buckling internal forces and critical out-plane buckling load of variable cross-section arches subjected to a uniformly distributed radial local load. It is found that the internal forces and the out-plane buckling load of an arch are significantly affected by the variation of cross-sectional height. As the ratio of the arch’s cross-sectional height increases, the bending moment decreases, and the axial force and critical out-plane buckling load increase. Analytical solutions of pre-buckling internal force and critical out-plane buckling load problems for arches with variable cross-sections have a wider significance since they can provide an effective explicit analytic method for the optimal design of arch structures.
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Liu, Yande, Yanrui Zhou et Yuanyuan Pan. « Online quantitative analysis of soluble solids content in navel oranges using visible-near infrared spectroscopy and variable selection methods ». Journal of Innovative Optical Health Sciences 07, no 06 (21 octobre 2014) : 1350065. http://dx.doi.org/10.1142/s179354581350065x.
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Variable selection is applied widely for visible-near infrared (Vis-NIR) spectroscopy analysis of internal quality in fruits. Different spectral variable selection methods were compared for online quantitative analysis of soluble solids content (SSC) in navel oranges. Moving window partial least squares (MW-PLS), Monte Carlo uninformative variables elimination (MC-UVE) and wavelet transform (WT) combined with the MC-UVE method were used to select the spectral variables and develop the calibration models of online analysis of SSC in navel oranges. The performances of these methods were compared for modeling the Vis-NIR data sets of navel orange samples. Results show that the WT-MC-UVE methods gave better calibration models with the higher correlation coefficient (r) of 0.89 and lower root mean square error of prediction (RMSEP) of 0.54 at 5 fruits per second. It concluded that Vis-NIR spectroscopy coupled with WT-MC-UVE may be a fast and effective tool for online quantitative analysis of SSC in navel oranges.
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Afandi, Pandi, et Helwen Heri. « Influence Factors Internal and External Factors Motivation and Performance of Employees : Do not Stay Civil Service Policy Unit ». International Journal of Economics and Finance 8, no 6 (24 mai 2016) : 258. http://dx.doi.org/10.5539/ijef.v8n6p258.
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<p>This research of background that directional and effective use of labor represent key toward the make-up of officer performance so that need to District Police Public Service head to make a manage the members always enthusiastic in working and having positive in executing work.Effort roomates can be a head-to Increase the activity spirit of enthusiasm, that is by giving good motivation and job performance.Intention of this research is to know and Analyzed do internal factors variable, external factor variable and motivation have influenced the which significantly either through partial and Also simultaneously to job performance officer, and Also from internal factors variable, external factor variable and motivation is the which most having an effect on the which to job performance officer.</p><p>This research is a survey verification sampling on 200 people from 236 respondend contract employee population of District Police Public Service Riau Province.This research represent research highlighting clarification relation between research variables and test hypotheses have been Formulated Previously roomates.Hereinafter technique intake of sample is used by population technique, where samples taken pursuant to SEM formula for 25 manifest variables using a minimum of 200 samples.Technique Analyzed using descriptive and quantitative analysis by applying the method of Structural Equation Modelling (SEM) with Analysis of Moment Structures (AMOS) programe.</p>
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Kidron, Aviv, Yuval Ofek et Herztel Cohen. « New perspective on the black box of internal auditing and organisational change ». Managerial Auditing Journal 31, no 8/9 (5 septembre 2016) : 804–20. http://dx.doi.org/10.1108/maj-07-2015-1220.
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Purpose The shift from the traditional audit towards performance audit implies that internal auditors in the public sector function as change agents who underpin the fundamental change process. This paper aims to propose a model that identifies the determinants of organisational change in the public sector that result from internal auditing and the way internal auditors facilitate it. Design/methodology/approach The conceptual discussion of this paper is based on a review of relevant literature, both practical and academic. Findings This paper develops an innovative model that describes the factors leading to auditees’ change readiness after undergoing internal audit processes. The independent variable is audit information quality and the dependent variable, organisational change. Auditees’ perceptions is the mediator variable, and accessibility to audit information is the moderator variable. Practical implications The proposed model suggests the advantages that can be gained by audit-related services, which in turn will add value to the organisation. The relationships between the variables inform practitioners on how to support effective audits as a means of increasing performance and influencing organisational change. Originality/value As the paper offers an innovative model, it may open up new research areas in internal auditing that can be studied by using both qualitative and quantitative methods.
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Song, Yuegang, Songlin Jin et Zhenhui Li. « Venture Capital and Chinese Firms’ Technological Innovation Capability : Effective Evaluation and Mechanism Verification ». Sustainability 14, no 16 (18 août 2022) : 10259. http://dx.doi.org/10.3390/su141610259.
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Making the financial industry a solider mainstay of the real economy is of great concern for China in the midst of economic reform. For China, leveraging venture capital (VC) to enhance a firm’s technological innovation capability (TIC) is an important means of actualising its innovation and development strategy, as well as a must-do to realise sustainable development. In this study, firms that went public from 2010 to 2020 on the A-stock market were used as samples to study the effects of VC on TIC and the relevant mechanism based on the difference-in-differences (DID) method. As research findings show, VC can improve TIC through the medium of the internal incentive and external constraint easing effects. The contributory role of VC in TIC varies with firm size, ownership, and industry type. A range of robustness tests, including the PSM, variable substitution, and instrumental variable methods, further strengthened the reliability of the conclusions. This study can enlighten policymakers on how to implement comprehensive resource factor market reform to build a favourable innovation environment that materialises the role of marketisation.
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Jumadi, Jumadi. « Pengaruh Pemasaran Internal dan Kualitas Layanan Internal Terhadap Kepuasan Pelanggan Internal (Studi Pada Industri Kepariwisataan di Daerah Istimewa Yogyakarta) ». Jurnal Ekonomi dan Bisnis 17, no 3 (18 juin 2016) : 17. http://dx.doi.org/10.24914/jeb.v17i3.285.
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<em>The aim of this research is to investigate the implication of internal marketing and internal service quality effectivity towards internal customer satisfaction in Tourism Industry in Yogyakarta Special Territory. This internal marketing studyinvolves variables of motivation and reward system, effective communication, effective employee's selection, effective recruitment, effective development, effective support system, and healthy work environment. While the internal quality service aspects that will be examined in this study are: tangible, emphaty, responsiveness, reliability and assurance, and then their influences on internal customer satisfaction would be analyzed.The sample size is 210 respondents,which is determined using purposive sampling method. The main instrument for data collection in this study is through questionnaire. The analysis tool used to examine the hypothesis of the study is Structural Equation Modeling using AMOS Version 20.0 Software. The result of the study shows that: Internal marketing and internal quality service significantly influence internal customers satisfation. However, the internal quality service influence the internal customers satisfaction more significantly. Therefore the managers in tourism industry should improve the internal marketing more than the internal quality service.</em>
Thèses sur le sujet "Effective Internal Variable method"
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Vernier, Patricia. « Homogenization of composite materials with fractional viscoelastic constituents ». Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS552.
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Cette thèse porte sur la prédiction des propriétés mécaniques effectives de matériaux hétérogènes composés de constituants viscoélastiques fractional, au moyen d'une approche incrémentale variationnelle. Nous appliquons la méthode Effective Internal Variable (EIV) développée par Lahellec and Suquet (2007), particulièrement attrayante pour le traitement de comportements viscoélastiques (Tressou et al., 2016). Contrairement aux méthodes d'homogénéisation communément utilisées qui reposent sur le principe de correspondance et pour lesquelles les fluctuations des champs ne sont pas accessibles, cette approche incrémentale permet de calculer les propriétés effectives dans le domaine direct au moyen des méthodes variationalles de Ponte Castañeda (1991 et 2002) qui prennent en compte les seconds-moments des champs mécaniques. La méthode EIV s'inscrit dans le cadre des Matériaux Standards Généralisés (MSG), dans lequel le comportement des matériaux dissipatifs est décrit par deux potentiels thermodynamiques convexes. Nous considérons des constituants viscoélastiques fractionnaires, dont la loi constitutive est décrite par des équations différentielles linéaires avec des dérivées fractionnaires. En accord avec des observations expérimentales, ce formalisme prend en compte des effets de mémoire longue à travers la superposition de plusieurs temps caractéristiques (Caputo et Mainardi, 1971). La distribution de ces derniers est donnée explicitement par l'expression du spectre en loi puissance. Les potentiels thermodynamiques des matériaux viscoélastiques fractionnaires sont définis en cohérence avec le cadre des MSG. Cette cohérence s'appuie sur l'interprétation rhéologique de l'élément fractionnaire comme un Maxwell généralisé (Lion, 1997). Ainsi, nous tirons parti de l'extension de la méthode EIV à plusieurs variables internes développée par Tressou et al. (2023) afin d'homogénéiser des matériaux composites contenant des constituants viscoélastiques fractionnaires. De plus, les temps caractéristiques sont adéquatement choisis à partir de la discrétisation du spectre. Cette discrétisation est réalisée avec la procédure de Papoulia et al. (2010), basée sur une méthode des trapèzes améliorée. Plus précisément, nous appliquons cette méthode à la fonction de Mittag-Leffler impliquée dans la définition des spectres de relaxation. Nous abordons deux problèmes hétérogènes différents au moyen de la méthode EIV. Nous considérons d'abord un composite de type matrice-inclusions sous chargement harmonique, pour lequel nous rencontrons des difficultés numériques. Nous évaluons ensuite la méthode EIV sur un polycristal de glace soumis à un essai de fluageThis PhD thesis deals with the prediction of the mechanical effective properties of composite materials with linear fractional viscoelastic constituents by means of an incremental variational approach. We make use of the Effective Internal Variable (EIV) method developed by Lahellec and Suquet (2007), which is particularly attractive for viscoelasticity (Tressou et al., 2016). Contrary to the common homogenization methods that rely on the correspondence principle and where the fluctuations are not accessible, this incremental method evaluates the effective properties into the direct domain through the variational methods of Ponte Castañeda (1991 and 2002) that take into account the second-moments of the fields. The EIV method is based on the Generalized Standard Materials framework, in which the dissipative materials are described by means of two convex thermodynamic potentials. We consider local fractional viscoelastic constituents, of which the constitutive behaviours follow linear differential equations with fractional derivative operators. In accordance with experimental observations, this formalism takes into account long-memory effects through the superposition of several characteristic times (Caputo and Mainardi, 1971). Their distribution is provided by the explicit expression of the spectrum as a power law. The potentials of fractional viscoelastic constituents are consistently defined in the GSM framework through the rheological interpretation of the fractional damping element as a generalized Maxwell model (Lion, 1997). Therefore, we take advantage of the extension of the EIV method to several internal variables, developed by Tressou et al. (2023) for the homogenization of composites with local fractional viscoelastic behaviours. Besides, the characteristic times are appropriately chosen by discretizing the spectrum. This is done using the midpoint-based procedure developed by Papoulia et al. (2010). More specifically, we apply their method to the Mittag-Leffler function involved in the definition of the relaxation spectrum. We use the EIV method to tackle two different heterogeneous problems. We consider a matrix-inclusion composite under harmonic loading, for which we come accros numerical issues. We then evaluate the EIV method for a polycrystal subject to a monotonous creep loading
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Craveiro, Marina Vendl. « Upheaval buckling of pipelines triggered by the internal pressure resulting from the transportation of oil and gas : theoretical discussions and geometrically nonlinear analysis using Finite Element Method ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-06122017-082632/.
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The pipelines used to transport oil and gas from the wellheads to the distribution and refining sites can be subjected to high levels of pressure and temperature. Under such conditions, the pipelines tend to expand, but, if the expansion is inhibited, a significant compressive axial force can arise, leading to their buckling, which can occur in the horizontal or vertical plane. In this context, the objective of the present work is to analyze the upheaval buckling of pipelines, considering the internal pressure to which they are subjected during the transportation of oil and gas as its only triggering. Using the concept of effective axial force, it aims at discussing two different approaches for considering the internal pressure in buckling problems: distributed loads dependent on pipeline curvature and equivalent compressive axial forces with follower and non-follower characteristics. It also discusses the influence of using static or dynamic analysis for such approaches. Concerning the upheaval buckling itself, the work intends to analyze and compare the influence of the soil imperfection amplitudes to the influence of the friction between the pipeline and the ground in the critical loads and in the post-buckling configurations of the pipeline. Besides theoretical research, the objectives are achieved through the development of various numerical models, since geometrically-simple models, without the consideration of the interaction between the pipeline and the ground, until more complex models, with the use of contact models to detect the ground and its imperfections. The models are developed in Giraffe (Generic Interface Readily Accessible for Finite Elements) using geometrically-exact finite element models of beams, undergoing large displacements and finite rotations. Through the research, it is concluded that there is an equivalence between the application of the internal pressure as a distributed load dependent on pipeline curvature and the application of the internal pressure as a follower compressive axial force. Besides this, it is demonstrated that the type of the analysis (static or dynamic) depends on the nature of the physical system analyzed. With the aid of results presented in terms of internal pressure, classical results about the influence of the imperfection amplitudes and of the friction between the pipeline and the ground in buckling are confirmed. It is also showed that the imperfection amplitudes analyzed play a more important role in the post-buckling configurations of the pipeline than the friction.Os dutos utilizados para transportar petróleo e gás natural das reservas até os locais de distribuição e refino podem estar submetidos a elevados níveis de pressão e temperatura. Sob tais condições, os dutos tendem a se expandir, porém, se a expansão é inibida, uma força axial de compressão significativa pode surgir nos dutos, ocasionando a flambagem lateral ou vertical dos mesmos. Dentro desse contexto, o objetivo do presente trabalho é analisar a flambagem vertical de dutos, considerando a pressão interna à qual eles estão submetidos durante o transporte de petróleo e gás natural como o único parâmetro desencadeador da flambagem. Usando o conceito de força axial efetiva, o trabalho objetiva discutir duas abordagens diferentes para considerar a pressão interna nos problemas de flambagem: carregamentos distribuídos dependentes da curvatura do duto e forças axiais de compressão equivalentes à pressão com caráter seguidor e não seguidor. O trabalho também discute a influência de usar a análise estática ou dinâmica para analisar essas abordagens de carregamento. Com relação à flambagem vertical propriamente dita, o trabalho pretende analisar e comparar a influência das amplitudes das imperfeições presentes no solo com a influência do atrito entre o duto e o solo nas cargas críticas e nas configuração pós-críticas do duto. Além de pesquisa teórica, os objetivos são atingidos através do desenvolvimento de vários modelos numéricos, desde modelos geometricamente simples, sem a consideração da interação entre o duto e o solo, até modelos mais complexos, com o uso de modelos de contato para detectar o solo e suas imperfeições. Os modelos são desenvolvidos no Giraffe (Generic Interface Readily Accessible for Finite Elements) usando elementos finitos geometricamente exatos de viga, sujeitos a grandes deslocamentos e rotações finitas. Através da pesquisa, conclui-se que existe uma equivalência entre a aplicação da pressão interna como um carregamento distribuído dependente da curvatura do duto e a aplicação da pressão interna como uma força axial de compressão seguidora. Além disso, demonstra-se que o tipo de análise (estática e dinâmica) depende da natureza do sistema físico analisado. Com a ajuda de resultados apresentados em termos de pressão interna, os resultados clássicos sobre a influência das amplitudes das imperfeições e do atrito entre o duto e o solo são confirmados. Também é mostrado que as amplitudes das imperfeições analisadas desempenham uma maior influência nas configurações pós-críticas do duto do que o atrito.
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Hall, Braydon Day. « The Dynamic Analysis of a Composite Overwrapped Gun Barrel with Constrained Viscoelastic Damping Layers Using the Modal Strain Energy Method ». DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1972.
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The effects of a composite overwrapped gun barrel with viscoelastic damping layers are investigated. Interlaminar stresses and constrained layer damping effects are described. The Modal Strain Energy method is developed for measuring the extent to which the barrel is damped. The equations of motion used in the finite element analysis are derived. The transient solution process is outlined. Decisions for selected parameters are discussed. The results of the finite element analyses are presented using the program written in FORTRAN. The static solution is solved with a constant internal pressure resulting in a calculated loss factor from the Modal Strain Energy Method. The transient solution is solved using the Newmark-Beta method and a variable internal pressure. The analyses conclude that strategically placed viscoelastic layers dissipate strain energy more effectively than a thick single viscoelastic layer. The optimal angle for maximizing the coefficient of mutual influence in a composite cylinder is not necessarily the optimal angle when viscoelastic layers are introduced between layers.
Livres sur le sujet "Effective Internal Variable method"
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Tuttle, Michael C. Search and Documentation of Underwater Archaeological Sites. Sous la direction de Ben Ford, Donny L. Hamilton et Alexis Catsambis. Oxford University Press, 2012. http://dx.doi.org/10.1093/oxfordhb/9780199336005.013.0005.
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Archaeological survey is fundamental to archaeological data collection. Underwater archaeology is developing and maturing as a discipline. The levels of technology available for investigations are variable depending on the objectives of surveys. Prior to entering the field, it is essential to do a complete desktop research, an in-office examination of available literature, and to develop a survey plan. This article describes different methods and the tools used for probing, which are used for examining subsurface features or defining the extent of a site. Remote sensing is an effective method to search for cultural material in a marine context. Once a general survey has located acoustic targets, magnetic anomalies, or other areas of interest, a predisturbance site survey of the targets may be conducted. Accurate positioning during a predisturbance investigation is critical. With an area survey complete or a predisturbance survey conducted, the next step in the archaeological process is excavation.
Chapitres de livres sur le sujet "Effective Internal Variable method"
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Sahni, S., B. C. Vemuri, F. Chen et C. Kapoor. « Variable-Bit-Length Coding : An Effective Coding Method ». Dans Visual Information and Information Systems, 665–74. Berlin, Heidelberg : Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-48762-x_82.
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Zheng, Huankun, Xianrong Chang et Yaoqin Sun. « An Effective Variable Step Method Based on Implicit Tuned Taylor Series Method ». Dans Proceedings of the 2012 International Conference on Cybernetics and Informatics, 2245–52. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-3872-4_287.
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Xing, Zhang, Lai Jun Biao et He Qing Zhi. « A New Solution of Complex Variable-Variation Method to Finite Plate with Internal Crack ». Dans Computational Mechanics ’88, 412–13. Berlin, Heidelberg : Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-61381-4_100.
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Khiabani, Behnam Naserian. « In Vitro Based Mass-Screening Technique for Early Selection of Banana Mutants Resistant to Fusarium Wilt ». Dans Efficient Screening Techniques to Identify Mutants with TR4 Resistance in Banana, 47–63. Berlin, Heidelberg : Springer Berlin Heidelberg, 2022. http://dx.doi.org/10.1007/978-3-662-64915-2_4.
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AbstractBanana and plantains are among the most valuable agricultural commodities in the world. Banana Fusarium wilt, caused by the soil-borne Fusarium oxysporum f. sp. cubense (Foc), is one of the most devastating diseases of banana globally. In the 1990s a new strain of Fusarium oxysporum called tropical race 4 (TR4) emerged in Southeast Asia that affected commercial Cavendish plantations. The development of resistant cultivars is an effective strategy for management of the disease. Field-based screening to identify Foc-resistant plants is time-consuming, expensive and is often challenged by variable environmental conditions. Here we present an early selection protocol enabling evaluation of the disease under in vitro conditions. This method provides a preliminary screening and allows evaluation of a large number of in vitro plantlets. Using this method, within a short time and in a small laboratory, breeders can evaluate thousands of banana plantlets, produced via irradiation. Subsequently, putative, disease-resistant mutant lines can be identified and evaluated in the field.
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Wang, Junyi, Xueting Zhai et Qiuju Luo. « How COVID-19 Impacts Chinese Travelers’ Mobility Decision-Making Processes : A Bayesian Network Model ». Dans Information and Communication Technologies in Tourism 2021, 557–63. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65785-7_53.
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AbstractThe outbreak of the COVID-19 pandemic has a multi-faceted impact on the mobility of travelers. Current research has not yet explained the internal mechanisms of travelers’ mobility changes during the pandemic. The Bayesian network is considered to be an effective method to describe the causality between the factors and output of a system. Thus, this paper established a Bayesian network model to analyze the impact of COVID-19 on Chinese travelers’ mobility decision–making processes. The model for the traveler mobility decision-making process is built on both a qualitative and quantitative analysis of travelers’ self-narration articles. Results show that official information, traffic information, family structure, and social interaction networks are the key factors affecting Chinese travelers’ mobility.
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Tang, Wei, Baohua Sun, Rongqiang Feng, Chenxi Huang et Lei Zhao. « A Distribution Network Reconfiguration Continuous Method Based on Efficient Solution Space Coding ». Dans Frontiers in Artificial Intelligence and Applications. IOS Press, 2022. http://dx.doi.org/10.3233/faia220583.
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This paper proposes a distribution network reconfiguration (DNR) continuous method to reduce network loss, balancing load, eliminating overload and improving power quality. When a certain coding rule reduces the dimension and reduces the radius of the variable confidence interval, the first type of non effective solution is avoided in probability through the coding rules and algorithm characteristics, and the second type of non effective solution is completely avoided compared with the expert base, so that the number of power flow calculations is greatly reduced. Through improved Crisscross optimization algorithm (CSO), the directionality is introduced into the horizontal crossing, and the fuzzy clustering idea is adopted to dynamically change the static vertical crossing factor, the simulation results show convergence speed and accuracy are improved, and verify the correctness and effectiveness of the method.
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Biliuk, Anatolii, et Olena Diachynska. « THE APPLIED ORIENTATION OF THE PHYSICS COURSE AS AN EFFECTIVE TOOL FOR FORMING THE PROFESSIONAL COMPETENCE MODEL OF FUTURE TECHNOLOGICAL ENGINEERS ». Dans Modern educational technologies in the training of specialists in the agricultural sector during the crisis. Publishing House “Baltija Publishing”, 2023. http://dx.doi.org/10.30525/978-9934-26-298-2-1.
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Reliability of structures is the most important problem in modern meсhanical engineering. Its solution poses the task of creating materials with high stable physical, mechanical, chemical and other properties. The materials that make up the basis of structures are, as a rule, operated in variable fields of various nature (mechanical, temperature, etc.), therefore they continuously change their properties. In this regard, progress in the field of mechanical engineering cannot be achieved without full knowledge of the real structure of materials, without a deep understanding of the microprocesses that occur in the materials during their processing and operation.Therefore, the purpose of the work is to describe methods and techniques for determining damping, structural and mechanical characteristics of materials and to evaluate the nature of their changes under the influence of temperature, time and force factors.The most promising non-destructive physical research methodsinclude the method of mechanical spectroscopy (internal friction) and the microhardness method. With the help of the method of mechanical spectroscopy, it is possible to reliably determine such seemingly different properties of materials as the ability to dampen vibrations arising during the operation of machine parts, the diffusion mobility of atoms in the crystal lattice and along dislocations. Internal friction (IF), which characterizes the ability to dissipate the energy of mechanical vibrations with a large and small amplitude in the material, can often be unambiguously associated with the number and mobility of dislocations and point defects of the crystal lattice. At the same time, it allows you to assess the material's susceptibility to another consequence, creep and grain boundary relaxation. Processes such as separation and dissolution of residual phases, relaxation, rest, hardening and tempering, dispersion hardening, plastic deformation and deformation aging and return have been successfully studied for many years by the method of internal friction. IF not only makes it possible to determine damping, structural and mechanical characteristics, but also to follow the nature of their changes in the fields of various nature [1–4]. Microhardness, which characterizes the energy of the interatomic bond of the crystal, its mechanical strength or the resistance of the crystal lattice to large plastic deformations and destruction, was chosen as a controlling characteristic in the study of the results.The research results showed that thermal cycling leads not only to the for-mation of high density dislocations in alloys, but also to their redistribution into polygonal walls. This is due to the fact that the available impurities, their complexes or separate dispersed allocations significantly block the newly formed dislocations and the already formed substructure, and thus increase its thermal stability and increase the heat resistance of the material. At the same time, as the strength characteristics increase, the damping properties are not significantly lost.Value/originality. Application of thermocycling under load is possible not only for materials made of dispersion-hardening alloys, which serve as raw materials for technology and industry, but also for finished parts and technical structures made of them. This will simplify the processing technology, reduce energy consumption and allow to obtain a significant economic effect.
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Raff, Lionel, Ranga Komanduri, Martin Hagan et Satish Bukkapatnam. « Configuration Space Sampling Methods ». Dans Neural Networks in Chemical Reaction Dynamics. Oxford University Press, 2012. http://dx.doi.org/10.1093/oso/9780199765652.003.0008.
Texte intégralRésumé :
In order to achieve the maximum accuracy in characterizing the PES and the associated force fields for an MD investigation, careful preparation of the database is an essential step in the process. The points that must be addressed include the following: 1. The total volume of configuration space is extremely large, and its size increases as the internal energy of the system rises. For example, consider a four-atom system. For this system, at least six internal coordinates must be specified to determine the spatial configuration of the molecular system. At a given internal energy, each of these six coordinates can span a continuous range of values from some minimum to some maximum. If each variable range is divided into 100 equal increments and the potential energy of the system computed by some ab initio method for all possible configurations of the system, a total of 1006or 1012 electronic structure calculations would need to be executed. This is clearly beyond the computational capabilities of any computational system currently in existence. Grid sampling methods can and have been used effectively for three atom systems. However, for more complex systems, it is essential that procedures be developed that permit the regions of configuration space that are important in the reaction dynamics to be identified. 2. Sampling methods usually should be optimized to produce a reasonably uniform density of data points in those regions of configuration space that are important in the dynamics. If this is not done and there are regions of very high point density and others with low point density, no fitting technique will function well. The parameters of the method will adjust themselves to fit regions of high density preferentially over those with low density even when the low-density regions may be more important in the dynamics. An exception to the need to have an approximately uniform density of points in the database occurs in regions where the potential gradient is large. In such regions, the density of points in the database will need to be larger than in regions in which the gradient is small.
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Abdelsabour Fahmy, Mohamed. « Boundary Element Modeling and Simulation Algorithm for Fractional Bio-Thermomechanical Problems of Anisotropic Soft Tissues ». Dans Recent Developments in the Solution of Nonlinear Differential Equations. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96268.
Texte intégralRésumé :
The main purpose of this chapter is to propose a novel boundary element modeling and simulation algorithm for solving fractional bio-thermomechanical problems in anisotropic soft tissues. The governing equations are studied on the basis of the thermal wave model of bio-heat transfer (TWMBT) and Biot’s theory. These governing equations are solved using the boundary element method (BEM), which is a flexible and effective approach since it deals with more complex shapes of soft tissues and does not need the internal domain to be discretized, also, it has low RAM and CPU usage. The transpose-free quasi-minimal residual (TFQMR) solver are implemented with a dual-threshold incomplete LU factorization technique (ILUT) preconditioner to solve the linear systems arising from BEM. Numerical findings are depicted graphically to illustrate the influence of fractional order parameter on the problem variables and confirm the validity, efficiency and accuracy of the proposed BEM technique.
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Allendorf, Fred W., W. Chris Funk, Sally N. Aitken, Margaret Byrne et Gordon Luikart. « Effective Population Size ». Dans Conservation and the Genomics of Populations, 133–50. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780198856566.003.0007.
Texte intégralRésumé :
We expect heterozygosity to be lost at a rate of 1/2N per generation in an ideal population because of genetic drift where N is the census population size. The effective size of a population is the size of the ideal (Wright–Fisher) population that will result in the same amount of genetic drift as in the actual population being considered. Heterozygosity is generally lost at a rate much faster than 1/2N in natural populations primarily because reproductive success is much more variable than assumed in an ideal population. Therefore, the effective size of natural populations (N e) is often much smaller than the census population size (N e << N). Predicting the rate of loss of heterozygosity over calendar time in a population requires an estimate of both N e and the generation interval. Genomic techniques provide a variety of methods to estimate N e in natural populations.
Actes de conférences sur le sujet "Effective Internal Variable method"
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Ye, Zhengmao, Liguang Li et Habib P. Mohamadian. « Multi-Variable Optimization on Variable Intake Valve Closing Timing System for Engine Overall Performance ». Dans ASME 2005 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ices2005-1099.
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Variable valve timing (VVT) technology has a remarkable impact on engine power output, fuel economy and emission levels. To achieve a tradeoff among its potential benefits on various aspects, a novel multi-objective optimization method is proposed to complement among engine performances over entire speed-load regions. Intake valve closing (IVC) timing has been widely accepted to be the most effective means of VVT technologies. IVC timing is therefore investigated to accomplish engine overall performance optimization. The bench tests have been conducted using an introduced variable working position belt extender system. A 5-valve, double overhead cam (DOHC) spark ignition engine is selected. The sample testing data of engine power and torque outputs, fuel economy and emission levels are collected from engine bench tests, which are then interpolated with regular engine speed operating ranges via smoothing cubic spline fitting. For multi-objective control problem, principal component analysis can be conducted for the multiple-objective analysis by alternating different engine parameters, such as valve timing, sparking timing, A/F ratio, and so on. On account of the extra expense of engine experiments, a simplified optimization approach is then formulated in order to analyze the potential of IVC technology in terms of engine power output and fuel economy under constraints of emission levels at individual high speed, medium speed and low speed regions, etc. Variable IVC timing control has been shown in this research to improve engine performance throughout speed-load regions. Multi-variable optimization is also demonstrated to be feasible and effective for the optimal performance achievement on speed-load regions.
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Cho, Hyunkyoo, et K. K. Choi. « Iterative Most Probable Point Search Method for Problems With Mixture of Random and Interval Variables ». Dans ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67909.
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To represent input variability accurately, input distribution model for random variables should be constructed using many observations or data. However, for certain input variables, engineers may have only their bounds which represent input uncertainty. In practical engineering applications, both random and interval variables could exist at the same time. For the applications, to consider both input variability and uncertainty, inverse reliability analysis should be carried out considering the mixed variables and their mathematical correlation in performance measure. In this paper, an iterative most probable point (MPP) search method has been developed for the mixed variable problem. The random and interval variables update procedures are developed considering the features of mixed variable in the inverse reliability analysis. Both variable update methods proceed one iteration simultaneously to consider the mathematical correlation. An interpolation method is introduced to find better candidate MPP without additional function evaluations. Mixed variable design optimization (MVDO) has been formulated to obtain cost effective and reliable design in the presence of the mixed variables. In addition, the design sensitivity of probabilistic constraint has been developed for effective and efficient MVDO procedure. Using numerical examples, it is found that the developed MPP search method finds accurate MPP more efficiently than generic optimization method. In addition, it is verified that the developed method enables MVDO process with small number of function evaluations.
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Petrea, Renato Gabriel, Sergiu Cătălin Bîrgovan, Marin Chirazi et Pia Simona Făgăraș. « Internal Communication and Management by Obiectives in Sports Profile Institutions ». Dans 80th International Scientific Conference of the University of Latvia. University of Latvia Press, 2022. http://dx.doi.org/10.22364/htqe.2022.79.
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Effective communication is required not only in interpersonal/human relationships but also in a successful management. In the real world, there is no organization without good communication. Since the acceptance of “management” as a separate body of knowledge over a half century ago, no management tool has had such a pervasive impact on organizations as the management by objectives. In this article, a cross-sectional study was conducted using the survey method based on a questionnaire with 24 items (10 items for the variable internal communication; 10 items for the variable management by obiectives and 4 items for demographic data: gender, age, city and work institutions). The main objective of this study is to show what kind of connection there is between the variable internal communication and the variable management by objectives among teachers from high schools with sports program and the teachers from faculties of physical education and sports in the Eastern side of Romania (Moldova Region). We also wanted to see if there is a difference between internal communication among high school teachers compared to university teachers. The same aspect of the difference was analyzed in the case of the management by obiectives variable. The study has 127 validated questionnaires that were completed by 80 teachers working in eight high schools with sports program and 47 teachers working in four faculties of physical education and sports in the Eastern side of Romania.
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Burk, Reinhard, Frederic Jacquelin et Russell Wakeman. « Using Co-Simulation Methods to Establish Variable Valve Actuation Hardware Specifications and Control Strategies ». Dans ASME 2001 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-ice-427.
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Abstract With the increasing recognition that variable valve actuation (VVA) in its various forms is a powerful tool for optimizing the performance of internal combustion engines, more and more production systems are being designed and implemented throughout the industry. However, as these control systems become more capable of altering lift, timing, duration, and even the number of valve events, the complexity of designing algorithms and calibrating them becomes enormous. In addition, without prior knowledge of an engine’s response to these algorithms, designing a cost-effective mechanism which provides adequate but not over-reaching capability is difficult. Ricardo has developed methodology for timestep coupled simulations which enables the use of one-dimensional (1-D) gas dynamics simulation of engine performance (WAVE™) coupled to a simulation of the valve actuation mechanism constructed in MATLAB® and AMESim®. This arrangement allows valve motion input to the 1-D code to be controlled either manually or by a VVA controller simulation, allowing such engine parameters as torque, fuel consumption, NVH, and EGR rates to be monitored as a function of valve timing strategy. This method allows the examination of such engine development concerns as tolerances, valve velocities and accelerations, and interactions with other engine controls to be studied without the costs, leadtimes, or hardware reliability problems that are associated with prototyping a VVA system. In addition, the interfacing of the valve control/engine performance simulation combination with the Design of Experiments optimization software iSIGHT allows the control system space to be explored automatically, without the brute force numerical search required to examine all permutations of the control strategies. The output of this procedure is an array of requirements which can be quickly translated into a specification document which will guide hardware and controls design efforts.
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Fu, Chiayu, I. Charles Ume et David L. McDowell. « Thermomechanical Stress Analyses of Plated-Through Holes in PWB Using Internal State Variable Constitutive Models ». Dans ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-0891.
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Abstract In application of multiaxial fatigue theories, extrapolation of concepts developed from uniaxial fatigue research must be used with caution. Previous related research on plated-through hole (PTH) fatigue investigations has been based on so-called effective stress/strain methods, which did not account for the fact that fatigue crack nucleation and growth is observed to occur on specifically oriented planes. Moreover, previous related thermal stress/strain analyses on PTH has been based on so-called bilinear constitutive relations for modeling copper plating with a linear kinematic hardening assumption, and this cannot capture many aspects of cyclic stress/strain behavior during thermal excursions. In this paper, thermal stress analyses using thermodynamics-based constitutive models of metallic consituents of PTHs are conducted by finite element package ABAQUS (1995) for multiaxial fatigue studies. Two types of PTHs (via) are investigated: ordinary empty PTH and PTH with solder filler. Two thermal profiles which simulate temperature fields in service are applied, with one experiencing the glass transition temperature of FR4. Residual stresses generated from previous process temperature history are considered. From the stress analyses, critical plane orientations for tensile type and shear type fatigue cracks are located.
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Huynh, T. C., J. K. Kang, K. C. Noh, Jong T. Lee et J. A. Caton. « Controlling Backfire Using Changes of the Valve Overlap Period for a Hydrogen-Fueled Engine Using an External Mixture ». Dans ASME 2007 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/icef2007-1702.
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The development of a hydrogen-fueled engine using an external mixture (e.g., using port or manifold fuel injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period while maintaining or improving engine performance. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. By using this research engine, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.3 and 1.2. The results showed that the developed hydrogen-fueled research engine with the mechanical continuous variable valve timing system has similar performance to a conventional engine with fixed valve timings, and is especially effective in controlling the valve overlap period. Backfire occurrence is reduced with a decrease of the valve overlap period, and is also significantly decreased even under operating conditions with the same volumetric efficiency. These results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a hydrogen-fueled engine while maintaining or improving performance.
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Bayliff, Scott, Bret Windom, Anthony Marchese, Greg Hampson, Jeffrey Carlson, Domenico Chiera et Daniel Olsen. « Controlled End Gas Auto Ignition With Exhaust Gas Recirculation on a Stoichiometric, Spark Ignited, Natural Gas Engine ». Dans ASME 2020 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icef2020-2979.
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Abstract The goal of this study is to address fundamental limitations to achieving diesel-like efficiencies in heavy duty on-highway natural gas (NG) engines. Engine knock and misfire are barriers to pathways leading to higher efficiency engines. This study explores enabling technologies for development of high efficiency stoichiometric, spark ignited, natural gas engines. These include design strategies for fast and stable combustion and higher dilution tolerance. Additionally, advanced control methodologies are implemented to maintain stable operation between knock and misfire limits. To implement controlled end-gas autoignition (C-EGAI) strategies a Combustion Intensity Metric (CIM) is used for ignition control with the use of a Woodward large engine control module (LECM). Tests were conducted using a single cylinder, variable compression ratio, cooperative fuel research (CFR) engine with baseline conditions of 900 RPM, engine load of 800 kPa indicated mean effective pressure (IMEP), and stoichiometric air/fuel ratio. Exhaust gas recirculation (EGR) tests were performed using a custom EGR system that simulates a high pressure EGR loop and can provide a range of EGR rates from 0 to 40%. The experimental measurements included the variance of EGR rate, compression ratio, engine speed, IMEP, and CIM. These five variables were optimized through a Modified BoxBenken design Surface Response Method (RSM), with brake efficiency as the merit function. A positive linear correlation between CIM and f-EGAI was identified. Consequently, CIM was used as the feedback control parameter for C-EGAI. As such, implementation of C-EGAI effectively allowed for the utilization of high EGR rates and CRs, controlling combustion between a narrower gap between knock and lean limits. The change from fixed to parametric ignition timing with CIM targeted select values of f-EGAI with an average coefficient of variance (COV) of peak pressure of 5.4. The RSM efficiency optimization concluded with operational conditions of 1080 RPM, 1150 kPa IMEP, 10.55:1 compression ratio, and 17.8% EGR rate with a brake efficiency of 21.3%. At this optimized point of peak performance, a f-EGAI for C-EGAI was observed at 34.1% heat release due to auto ignition, a knock onset crank angle value of 10.3° aTDC and ignition timing of −24.7° aTDC. This work has demonstrated that combustion at a fixed f-EGAI can be maintained through advanced ignition control of CIM without experiencing heavy knocking events.
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You, Shaohua, Qinzhuo Liao, Mao Sheng, Gensheng Li, Yiqun Zhang, Chao Xiong et Jingbin Li. « Stress Sensitivity Analysis of Carbonate Digital Cores with Different Image Resolutions ». Dans 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0170.
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ABSTRACT The stress sensitivity of reservoirs plays an important role in the field of oil and gas exploration and development. As an effective stress sensitivity analysis method, digital core has the problem of excessive computational cost. We thus propose a low computational cost method for predicting core stress sensitivity. This paper first established digital cores of carbonate rocks under different effective stresses, then calculated permeability under different stresses by a new decoupling method. It simplified the three-dimensional pore-scale simulation to multiple decoupled two-dimensional ones and greatly reduced the computational complexity. Meanwhile, to solve the problem of high computational cost, we upscaled the CT images and tested the effect of image resolutions on the accuracy of the stress sensitivity analysis. The results show that the stress sensitivity of digital core image is similar to that of the original image after upscaling. We thus can use scaled image for the calculation of the stress sensitivity of core. This computationally effective method provides a basis for stress sensitivity prediction of tight lithology reservoirs. INTRODUCTION Reservoir stress sensitivity is an important research topic in the field of oil and gas exploration and exploitation. During oil and gas development, the pressure on the rock skeleton increases as the fluid in the reservoir space where the oil and gas migrate decreases. Pores, throats, and microfractures in the reservoir are compressed or destroyed, resulting in reduced permeability. This phenomenon is called the stress sensitivity of reservoir (Cao and Lei, 2019; Hu et al., 2020; Yang et al., 2021). In recent years, with the increasing proportion of unconventional oil and gas production, the study of reservoir stress sensitivity plays an increasingly important role in seismic interpretation, well-logging reservoir evaluation, reservoir stimulation, and oil and gas development (Wang et al., 2017). As a well-established method, pressure sensitive macroscopic experiments have been widely used. The loading method of stress sensitive macroscopic experiment is mainly divided into two categories: constant internal pressure with variable confining pressure and constant confining pressure with variable internal pressure (pore pressure). The loading method of constant confining pressure with variable internal pressure is to keep the confining pressure constant during the experiment, while gradually reducing the internal pressure. Then measure the permeability corresponding to different pressures, and obtain the stress sensitivity of permeability (Reyes and Osisanya, 2002). In comparison, the loading method of constant internal pressure with variable confining pressure is the opposite. During the development of oil and gas reservoirs, the pressure in the overlying formations is usually constant. The pore pressure gradually decreases with development, which alters the effective pressure. Therefore, the test method with constant confining pressure and variable internal pressure can better reflect the pressure variation properties of the actual reservoir. Many researchers have applied this method to the study of stress sensitivity (Chalmers et al., 2012; Ghanizadeh et al., 2014; Hou et al., 2017; Zeng et al., 2017). Reyes and Osisanya (2002) used the power law function to fit the relationship between porosity, permeability and net negative pressure, and obtained the stress sensitivity of porosity and permeability in unconventional reservoirs. It was found that the law of change of permeability with effective stress satisfies the exponential relation. Alramahi and Sundberg (2012) predicted the stress-related conductivity of hydraulic fractures and studied the relationship between rock mineralogy and mechanical properties of proppant embedding. Ghanizadeh et al. (2014) found that the anisotropy and stress sensitivity of permeability is related to mineral composition. Kumar et al. (2015) compared the stress sensitivity of fracture aperture and permeability with and without proppant. However, the macroscopic experiment can only compute stress-sensitive macroscopic results, with less concentration on the details of internal seepage space changes.
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Pan, Dinghao, et Andrea Vacca. « A Numerical Method for the Analysis of the Theoretical Flow in Crescent-Type Internal Gear Machines With Involute Teeth Profile ». Dans ASME/BATH 2019 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/fpmc2019-1605.
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Abstract Lumped parameter approaches for the description of the flow displaced by hydrostatic pumps and motors have proven to be very effective for both analysis and design purposes. However, while these methods are relatively easy to implement for most of the existing design architectures for positive displacement machines, the case of a crescent-type internal gear machine (CIGM) presents clear challenges as it pertains to the definition of lumped control volumes within the machine. This paper proposes an original scheme for defining lumped control volumes within a CIGM with involute teeth profiles, which is suitable for developing fluid dynamic simulation models for CIGMs. The proposed method strictly obeys fundamental rules on continuous volumes required by lumped parameters models. This is achieved by defining not only multiple control volumes for each displacement chamber but also two variable porting volumes to respect the volume conservation. To prove the validity of the proposed numerical method, the paper provides comparisons between the displaced volume found by the proposed lumped parameter approach and the theoretical kinematic flow ripple provided by an analytical formula available from literature. The results show how the method can be used as a design tool for CIGMs, and particularly to further develop lumped parameter simulation models for detailed fluid dynamic analysis of CIGMs.
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Lee, Taewon, et Rolf D. Reitz. « Response Surface Method Optimization of a HSDI Diesel Engine Equipped With a Common Rail Injection System ». Dans ASME 2001 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-ice-401.
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Abstract To overcome the trade-off between NOx and particulate emissions for future diesel vehicles and engines it is necessary to seek methods to lower pollutant emissions. The desired simultaneous improvement in fuel efficiency for future DI diesels is also a difficult challenge due to the combustion modifications that will be required to meet the exhaust emission mandates. This study demonstrates the emission reduction capability of EGR and other parameters on a High Speed Direct Injection (HSDI) diesel engine equipped with a common rail injection system using an RSM optimization method. Engine testing was done at 1757 rev/min, 45% load. The variables used in the optimization process included injection pressure, boost pressure, injection timing, and EGR rate. RSM optimization led engine operating parameters to reach a low-temperature and premixed combustion regime called the MK combustion region, and resulted in simultaneous reductions in NOx and particulate emissions without sacrificing fuel efficiency. It was shown that RSM optimization is an effective and powerful tool for realizing the full advantages of the combined effects of combustion control techniques by optimizing their parameters. It was also shown that through a close observation of optimization processes, a more thorough understanding of HSDI diesel combustion can be provided.
Rapports d'organisations sur le sujet "Effective Internal Variable method"
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Jia, Yunhui, Christopher S. Williams, Prince Baah et Mark D. Bowman. Long-Term Project and Network-Level NDT Implementation Plan for Indiana. Purdue University, 2023. http://dx.doi.org/10.5703/1288284317582.
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Bridge deck condition assessments in Indiana are primarily reliant on visual inspection. The condition of bridge decks, however, is highly dependent on deterioration under the surface, which includes the corrosion of steel reinforcement and concrete delamination. The implementation of reliable nondestructive testing (NDT) methods can provide information about such internal deterioration, but considering the multiple NDT methods currently available, guidance is needed to find the best approach for assessing bridge decks in the state’s bridge inventory. A research program was conducted to examine various NDT methods with the objective of recommending an effective NDT strategy for network-level and project-level bridge inspections in Indiana that will complement information from traditional bridge inspections and provide asset engineers with improved information for long-term programming decisions. For the study, several consultants used various NDT methods to inspect a set of bridge decks that represented a range of desired test variables. Based on the test results, it was determined that aerial infrared thermography (IRT) is a good network-level method that is capable of scanning a large number of bridges and providing an initial assessment of bridge deck conditions. If significant delamination activity is detected, then follow-up network-level scanning limited to the problematic bridge decks should be performed using vehicle-mounted IRT. For project-level scanning of individual bridge decks, impact echo was found to be reliable and repeatable. For bridges with high-traffic volume for which project-level scanning is needed, a pole-mounted IRT system was found to be effective for evaluating the deck condition.
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Liller, Otto K. Special Operations Forces and Foreign Internal Defense : An Effective Counterterrorism Method. Fort Belvoir, VA : Defense Technical Information Center, février 2005. http://dx.doi.org/10.21236/ada464349.
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Kott, Phillip S. The Degrees of Freedom of a Variance Estimator in a Probability Sample. RTI Press, août 2020. http://dx.doi.org/10.3768/rtipress.2020.mr.0043.2008.
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Inferences from probability-sampling theory (more commonly called “design-based sampling theory”) often rely on the asymptotic normality of nearly unbiased estimators. When constructing a two-sided confidence interval for a mean, the ad hoc practice of determining the degrees of freedom of a probability-sampling variance estimator by subtracting the number of its variance strata from the number of variance primary sampling units (PSUs) can be justified by making usually untenable assumptions about the PSUs. We will investigate the effectiveness of this conventional and an alternative method for determining the effective degrees of freedom of a probability-sampling variance estimator under a stratified cluster sample.
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Liu et Nixon. L52305 Probabilistic Analysis of Pipeline Uplift Resistance. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), juin 2010. http://dx.doi.org/10.55274/r0000002.
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To investigate the feasibility of probabilistic analyses of the peak uplift resistance in frozen soils by varying parameters that are known to be important for the development of the uplift resistance under the upward movement of a pipe. A buried pipeline will be subjected to a variety of forces, both internal and external, including the interaction of the pipe with the surrounding soil. The soil-pipe interaction in permafrost regions have to account for the behavior of frozen and unfrozen soil, and transitions between the two as the pipeline traverses in a discontinuous permafrost zone. The variations in the properties and behavior of frozen soils are expected to be substantial in three dimensions of the Right-of-Way (ROW) and with time (seasonal fluctuations and changes with the history of pipeline operation). Given the uncertainties with frozen soil properties and the changes in behavior with time and location, a large variation in soil-pipe interaction characteristics can exist. The uplift resistance of a pipeline is one of these soil-pipe interactions that can be impacted by a variation in soil condition and state. A need was identified to outline the use of a probabilistic analysis of pipe uplift resistance in an attempt to capture the magnitude of these variations and uncertainties of frozen soil and the impact on the soil-pipe interaction. The probabilistic analysis allows the designer of a pipeline to consider a range of uplift resistance to a certain confidence level that would represent the likely values that a pipe may be subjected to. The work presented in this report is more focused on the methodology of the probabilistic approach, rather than the analysis itself for a specific design case, even though an example is provided for illustration purposes. A series of numerical simulations using Fast Lagrangian Analysis of Continua (FLAC) were completed varying one parameter with each run to develop a library of peak uplift resistances for a variety of different temperatures, soil properties and pipe parameters. The FLAC model was previously developed for PRC, a summary of this report is provided here to outline important parameters that were used to complete this analysis. The simulations were used to develop a correlation of peak uplift resistance as a function of soil tensile strain limit, modulus of deformation, and creep of frozen soils. Each of these parameters is dependent of the pipeline conditions such as temperature, displacement rate, and effective frozen cover depth. It is noted that the scope of the work was to develop a probabilistic method of estimating peak uplift resistance in frozen soils. Even though some sensitivity analysis were carried out, as outlined later in this report, to assess the impacts of the variable, detailed uncertainty analysis or risk assessment were not performed.
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Pilkevych, Ihor, Oleg Boychenko, Nadiia Lobanchykova, Tetiana Vakaliuk et Serhiy Semerikov. Method of Assessing the Influence of Personnel Competence on Institutional Information Security. CEUR Workshop Proceedings, avril 2021. http://dx.doi.org/10.31812/123456789/4374.
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Modern types of internal threats and methods of counteracting these threats are analyzed. It is established that increasing the competence of the staff of the institution through training (education) is the most effective method of counteracting internal threats to information. A method for assessing the influence of personnel competence on institutional information security is proposed. This method takes into account violator models and information threat models that are designed for a specific institution. The method proposes to assess the competence of the staff of the institution by three components: the level of knowledge, skills, and character traits (personal qualities). It is proposed to assess the level of knowledge based on the results of test tasks of different levels of complexity. Not only the number of correct answers is taken into account, but also the complexity of test tasks. It is proposed to assess the assessment of the level of skills as the ratio of the number of correctly performed practical tasks to the total number of practical tasks. It is assumed that the number of practical tasks, their complexity is determined for each institution by the direction of activity. It is proposed to use a list of character traits for each position to assess the character traits (personal qualities) that a person must have to effectively perform the tasks assigned to him. This list should be developed in each institution. It is proposed to establish a quantitative assessment of the state of information security, defining it as restoring the amount of probability of occurrence of a threat from the relevant employee to the product of the general threat and employees of the institution. An experiment was conducted, the results of which form a particular institution show different values of the level of information security of the institution for different values of the competence of the staff of the institution. It is shown that with the increase of the level of competence of the staff of the institution the state of information security in the institution increases.
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Ladd, Neuner et Olsen. PR-179-13207-R01 Variable Fuel Composition Air Fuel Ratio Control of Lean Burn Engines. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), mars 2016. http://dx.doi.org/10.55274/r0010864.
Texte intégralRésumé :
This research evaluates the effects of variable fuel quality on a large bore 2 stroke natural gas engine by varying ethane in the fuel gas from 5 to 25%. Four control strategies were evaluated at ~2 g/bhp-hr NOx, constant boost control, trapped gas ratio (TGR) control, trapped equivalence ratio (TER) control and a novel NOx sensor feedback control methodology. These control approaches were evaluated during variations in intake manifold temperature, relative humidity, ethane volume percentage, and engine speed. Emissions, combustion parameters, controller performance, and engine performance were measured and compared. During a second phase of testing the impact of fuel quality and other parameters (ignition timing, air manifold temperature, and TER) on detonation was explored at ?15 g/bhp-hr NOx. Techniques to quantify detonation were also evaluated, including a commercial accelerometer based system by Altronic. It was determined that ignition timing was the most effective method to control engine detonation. Fuel composition and TER were shown to have a significant effect on the severity of detonation. It was noted that persistent detonation lead to a steady increase in NOx production, but NOx values alone were inadequate to quantify detonation. At completion of engine testing the operational parameters were analyzed to create predictive models to determine if the engine would begin to detonate based on fuel composition, ignition timing and TER. The generated models accurately predicted the detonation level of the engine. This report has a related webinar.
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Gipson et Trahan. PR-369-08609-R01 Online Gas Meter Cleaning. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), juin 2010. http://dx.doi.org/10.55274/r0010711.
Texte intégralRésumé :
To ensure proper operation and accuracy of Natural Gas meters, it is important that the meters and associated piping be maintained in a clean condition consistent with both manufacturer production and AGA report provisions. This can best be assured through a comprehensive diagnostic and in section program complete with efficient internal cleaning as required. The objective of this project was to provide a comparison between continuous chemical injection cleaning with the system remaining online and conventional manual disassembly and cleaning techniques with the system offline. Representative samples of fouling materials were collected from two designated meter locations for complete identification analysis and cleaning product screening. The results from these tests are intended to assist in selecting the most effective product for the online cleaning method.
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Rahman, Shahedur, Rodrigo Salgado, Monica Prezzi et Peter J. Becker. Improvement of Stiffness and Strength of Backfill Soils Through Optimization of Compaction Procedures and Specifications. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317134.
Texte intégralRésumé :
Vibration compaction is the most effective way of compacting coarse-grained materials. The effects of vibration frequency and amplitude on the compaction density of different backfill materials commonly used by INDOT (No. 4 natural sand, No. 24 stone sand, and No. 5, No. 8, No. 43 aggregates) were studied in this research. The test materials were characterized based on the particle sizes and morphology parameters using digital image analysis technique. Small-scale laboratory compaction tests were carried out with variable frequency and amplitude of vibrations using vibratory hammer and vibratory table. The results show an increase in density with the increase in amplitude and frequency of vibration. However, the increase in density with the increase in amplitude of vibration is more pronounced for the coarse aggregates than for the sands. A comparison of the maximum dry densities of different test materials shows that the dry densities obtained after compaction using the vibratory hammer are greater than those obtained after compaction using the vibratory table when both tools were used at the highest amplitude and frequency of vibration available. Large-scale vibratory roller compaction tests were performed in the field for No. 30 backfill soil to observe the effect of vibration frequency and number of passes on the compaction density. Accelerometer sensors were attached to the roller drum (Caterpillar, model CS56B) to measure the frequency of vibration for the two different vibration settings available to the roller. For this roller and soil tested, the results show that the higher vibration setting is more effective. Direct shear tests and direct interface shear tests were performed to study the impact of particle characteristics of the coarse-grained backfill materials on interface shear resistance. The more angular the particles, the greater the shear resistance measured in the direct shear tests. A unique relationship was found between the normalized surface roughness and the ratio of critical-state interface friction angle between sand-gravel mixture with steel to the internal critical-state friction angle of the sand-gravel mixture.
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Wang, Xiaoyu. Pediatric tuina in treating recurrent respiratory tract infection in children : a systematic review and meta‑analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, avril 2023. http://dx.doi.org/10.37766/inplasy2023.4.0075.
Texte intégralRésumé :
Review question / Objective: Is pediatric tuina an effective treatment for recurrent respiratory tract infection in children? Condition being studied: Recurrent respiratory tract infection (RRTI) is a common disease in children, which refers to the recurrence of upper and lower respiratory tract infections within a year, exceeding the prescribed number of times. It is more common in infants under 3 years old. The disease is easy to relapse and lasts for a long time, affecting the normal growth and development of children and physical and mental health, easily causing other diseases, leading to a variety of chronic wasting diseases, and damaging the function of organs and the immune system. Immunotherapy and nutritional therapy are commonly used in Western medicine. At present, the treatment of RRTI in children with traditional Chinese medicine has achieved a certain effect, and the treatment mainly includes internal treatment and external treatment. Tuina therapy is one of the common therapies for the treatment of RRTI in children with traditional Chinese medicine. Because of its advantages, there are many literature reports on tuina treatment of this disease, with a good total effective rate, but whether its therapeutic effect is higher than other therapies has not been determined as a whole. This study used the method of systematic review to collect the published clinical research literature on the treatment of RRTI in children at home and abroad for systematic review, so as to provide a reference for clinical research.
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Baluk, Nadia, Natalia Basij, Larysa Buk et Olha Vovchanska. VR/AR-TECHNOLOGIES – NEW CONTENT OF THE NEW MEDIA. Ivan Franko National University of Lviv, février 2021. http://dx.doi.org/10.30970/vjo.2021.49.11074.
Texte intégralRésumé :
The article analyzes the peculiarities of the media content shaping and transformation in the convergent dimension of cross-media, taking into account the possibilities of augmented reality. With the help of the principles of objectivity, complexity and reliability in scientific research, a number of general scientific and special methods are used: method of analysis, synthesis, generalization, method of monitoring, observation, problem-thematic, typological and discursive methods. According to the form of information presentation, such types of media content as visual, audio, verbal and combined are defined and characterized. The most important in journalism is verbal content, it is the one that carries the main information load. The dynamic development of converged media leads to the dominance of image and video content; the likelihood of increasing the secondary content of the text increases. Given the market situation, the effective information product is a combined content that combines text with images, spreadsheets with video, animation with infographics, etc. Increasing number of new media are using applications and website platforms to interact with recipients. To proceed, the peculiarities of the new content of new media with the involvement of augmented reality are determined. Examples of successful interactive communication between recipients, the leading news agencies and commercial structures are provided. The conditions for effective use of VR / AR-technologies in the media content of new media, the involvement of viewers in changing stories with augmented reality are determined. The so-called immersive effect with the use of VR / AR-technologies involves complete immersion, immersion of the interested audience in the essence of the event being relayed. This interaction can be achieved through different types of VR video interactivity. One of the most important results of using VR content is the spatio-temporal and emotional immersion of viewers in the plot. The recipient turns from an external observer into an internal one; but his constant participation requires that the user preferences are taken into account. Factors such as satisfaction, positive reinforcement, empathy, and value influence the choice of VR / AR content by viewers.