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1
Celik, Gokhan, Bilgin Kaftanoğlu und Celalettin Karadogan. „Investigation of Influence Parameters on Forming Limit Diagrams of Aluminum Alloy-AA2024“. Key Engineering Materials 473 (März 2011): 382–89. http://dx.doi.org/10.4028/www.scientific.net/kem.473.382.
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Sheet metal forming technology is the keyword for many industries such as aerospace, aeronautics and automobile industries. Customer expectations, quality and safety requirements and market competitions require sheet metal forming operations to be well analyzed before the process to fulfill all these requirements. In this study, combination of FEA (finite element analysis) and mechanical material characterization were used in order to improve sheet metal forming operations while considering cost and quality. On the material characterization side of the studies, simple uniaxial tensile tests were conducted to obtain anisotropy parameters and yield points along different directions and hydraulic bulge test (HBT) was performed to obtain plastic behavior of the material up to 0.7 strains. Deformation measurements were conducted using optical measurement system GOM-ARAMIS while a 60-ton hydraulic press; Zwick/Roell BUP600 was used to deform the sheet part AA2024-0 aluminum alloy. Effects of process parameters, which are initial material thickness, lubrication and punch speed, on sheet metal formability and forming limit diagrams (FLDs) were investigated. On the study of thickness effects, sheet metals those having 0.81mm, 1.27mm and 1.60mm thickness were tested. Punch velocities of 250mm/min, 500mm/min and 750mm/min were used to investigate effect of punch speed on formability of sheet metals. Finally, PTFE (Polytetrafluoroethylene), paraffin lubricated and dry conditions were presented to obtain friction effects. FE analyses were performed to simulate experiments and to obtain friction coefficients of different lubricants. Good correlations were observed between numerical simulations and experimental results.
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Neamt, Liviu, Alina Neamt und Olivian Chiver. „Improved Procedure for Earth Fault Loop Impedance Measurement in TN Low-Voltage Network“. Energies 14, Nr. 1 (02.01.2021): 205. http://dx.doi.org/10.3390/en14010205.
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The difficulties and uncertainties related to earth fault loop impedance measurement are addressed in this paper. Based on the presentation of the measurement procedure implemented in the test equipment (diagrams and measured quantities, respectively, interpretation of results), the shortcomings and errors that accompany it are highlighted. The position in the power system, the influence of power transformers, and the use of effective quantities instead of phasors are important sources of errors, but, as will be seen, the switching of loads at the consumer sides and/or the occurrence of fault regimes during measurements can lead to the most serious impairment of the accuracy in the impedance assessment. The clarification of these aspects is achieved, both starting from the equivalent diagrams of the measurement circuits and the analytical interpretation of the phenomena associated with the measurements, as well as based on the modeling and simulation of TN low-voltage electrical distribution networks, in a specialized program, Eaton xSpider, which allows the complete and complex analysis of a large number of scenarios. Thus, essential conclusions were drawn regarding the level of errors and their causes, obviously, with the research coming with solutions to be implemented at the level of the measurement protocols of the devices used.
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Oprea, Corneliu I., Petre Panait, Zahraa M. Essam, Reda M. Abd El-Aal und Mihai A. Gîrțu. „Photoexcitation Processes in Oligomethine Cyanine Dyes for Dye-Sensitized Solar Cells—Synthesis and Computational Study“. Nanomaterials 10, Nr. 4 (02.04.2020): 662. http://dx.doi.org/10.3390/nano10040662.
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We report density functional theory (DFT) calculations of three newly synthesized oligomethine cyanine-based dyes as potential TiO2-sensitizers in dye-sensitized solar cells. The three dyes have π-symmetry and the same acceptor side, terminating in the carboxylic anchor, but they differ through the π-bridge and the donor groups. We perform DFT and time-dependent DFT studies and present the electronic structure and optical properties of the dyes alone as well as adsorbed to the TiO2 nanocluster, to provide some predictions on the photovoltaic performance of the system. We analyze theoretically the factors that can influence the short circuit current and the open circuit voltage of the dye-sensitized solar cells. We examine the matching of the absorption spectra of the dye and dye-nanocluster system with the solar irradiation spectrum. We display the energy level diagrams and discuss the alignment between the excited state of the dyes and the conduction band edge of the oxide as well as between the redox level of the electrolyte and the ground state of the dyes. We determine the electron density of the key molecular orbitals and analyze comparatively the electron transfer from the dye to the semiconducting substrate. To put our findings in the right perspective we compare the results of our calculations with those obtained for a coumarin-based dye used in fabricating and testing actual devices, for which experimental data regarding the photovoltaic performance are available.
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Zhang, Nan, Yaoyao Shi, Zhen Chen, Hongxia Chen, Jia Liu und Pan Zhao. „Chatter reliability prediction of side milling blisk“. Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 39, Nr. 1 (Februar 2021): 111–18. http://dx.doi.org/10.1051/jnwpu/20213910111.
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During the blisk side milling, the blade is thin and the tool suspension length is large, which is easy to occur milling system chatter. The wavy surface left by chatter has great effect on the surface roughness and service performance of the aero-engine blisk. To accurately predict the stability of the blisk side milling, the influence of random variables on the machining stability was considered. In this paper, the chatter reliability model of the blisk side milling system was established using the first-order second-moment method. The model takes structural parameters and spindle speed as random variables and chatter frequency as intermediate variables. The chatter reliability model was used to draw the reliability lobe diagram, which can be used to divide the machining reliability area. The effectiveness of this method was verified by experiments and compared with Monte Carlo method. The validation results showed that the reliability lobe diagram can be used to determine the stability probability prediction of blisk side milling and can replace the traditional stability lobe diagram.
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Rashid, H. S. J., C. S. Place, D. Mba, R. L. C. Keong, A. Healey, W. Kleine-Beek und M. Romano. „Reliability model for helicopter main gearbox lubrication system using influence diagrams“. Reliability Engineering & System Safety 139 (Juli 2015): 50–57. http://dx.doi.org/10.1016/j.ress.2015.01.021.
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6
Hsiao, Te Ching, und Shyh Chour Huang. „The Effect of Cutting Process Parameters on the Stability in Milling“. Advanced Materials Research 887-888 (Februar 2014): 1200–1204. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.1200.
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In the milling process, the dynamic system in the cutting process is composed of the tool, workpiece, and machine tools themselves. Therefore the mill geometric parameter, workpiece material behavior, and the modal parameters of the cutting system all will influence the stability in milling. Using FLN method and convolution force model to predict the chatter stability of milling process, and discussing the effect of milling parameter on the stability in this article. According to the result: with the increase of the tool diameter, stiffness, damping ratio or the reducing of tangential cutting force coefficient and radial width of cut, the stability lobe diagram tends to move upward. With the increase of natural frequency, the stability lobe diagram tends to move to right side. With the increase of the number of tooth, the stability lobe diagram tends to move downward.
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Rashid, H. S. J., C. S. Place, D. Mba, R. Lim, A. Healey, W. Kleine-Beek und M. Romano. „Helicopter MGB oil system failure analysis using influence diagrams and random failure probabilities“. Engineering Failure Analysis 50 (April 2015): 7–19. http://dx.doi.org/10.1016/j.engfailanal.2014.12.013.
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Keita, G., A. Ricard, R. Audebert, E. Pezron und L. Leibler. „The poly(vinyl alcohol)-borate system: influence of polyelectrolyte effects on phase diagrams“. Polymer 36, Nr. 1 (Januar 1995): 49–54. http://dx.doi.org/10.1016/0032-3861(95)90674-q.
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Li, Hong-Tao, Gang Zhao, Ying-Xin Ji und Yi-Chen Zhang. „Heat generation and side milling stability of titanium alloy“. Thermal Science 24, Nr. 6 Part B (2020): 4033–40. http://dx.doi.org/10.2298/tsci2006033l.
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In this paper, the thermal generation and milling stability of titanium alloy during machining are investigated mainly. A new definition of processing behavior is given based on the principles of minimization, entity expression and combination, and a model of side milling behavior is constructed. Through a series of side milling orthogonal experiments on Ti-6Al-4V titanium alloy, the cutting forces under different process parameters are obtained. Further, the cutting force coefficients of the model is calculated by the complete average algorithm and the peak average algorithm, and the milling stability of the system is analyzed by a stability lobe diagram. The results show that the different cutting parameters have important influences on the milling stability of titanium alloy.
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Gregorczyk, Magdalena, und Andrzej Rysak. „The influence of the Lorenz system fractionality on its recurrensivity“. MATEC Web of Conferences 252 (2019): 02006. http://dx.doi.org/10.1051/matecconf/201925202006.
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In this work, we investigate the recurrensivity of the Lorenz system with fractional order of derivatives occurring in its all three differential equations. Several solutions of the system for varying fractional orders of individual derivatives were calculated, which was followed by an analysis of changes in the selected recurrence quantifiers occurring due to modifications of the fractional orders {q1, q2, q3}. The results of the recurrence analysis were referred to the time series plots, phase diagrams and FFT spectra. The obtained results were finally used to examine the influence of fractional derivatives on the chaos - periodicity transition of the system dynamics.
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Velimirovic, Jelena D., und Aleksandar Janjic. „Risk Assessment of Circuit Breakers Using Influence Diagrams with Interval Probabilities“. Symmetry 13, Nr. 5 (21.04.2021): 737. http://dx.doi.org/10.3390/sym13050737.
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This paper deals with uncertainty, asymmetric information, and risk modelling in a complex power system. The uncertainty is managed by using probability and decision theory methods. More specifically, influence diagrams—as extended Bayesian network functions with interval probabilities represented through credal sets—were chosen for the predictive modelling scenario of replacing the most critical circuit breakers in optimal time. Namely, based on the available data on circuit breakers and other variables that affect the considered model of a complex power system, a group of experts was able to assess the situation using interval probabilities instead of crisp probabilities. Furthermore, the paper examines how the confidence interval width affects decision-making in this context and eliminates the information asymmetry of different experts. Based on the obtained results for each considered interval width separately on the action to be taken over the considered model in order to minimize the risk of the power system failure, it can be concluded that the proposed approach clearly indicates the advantages of using interval probability when making decisions in systems such as the one considered in this paper.
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Li, Bo, Jian Luo und Jin Fa Zhuang. „Research of Decision-Making in the Multi-Agent System Based on Interactive Influence Diagrams“. Key Engineering Materials 467-469 (Februar 2011): 1947–52. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.1947.
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Interactive influence diagrams(I-IDs) offer a transparent and representation for the decision-making in multiagent settings. In I-IDs, for the sake of predicting the behavior of other agent accurately, the modeling agent starts from an initial set of possible models for another agent and then maintains belief about which of those models applies. This initial set of models in the model node is typically a fully specification of possible agent types. Although such a rich space gives the modeling agent high accuracy in its beliefs, it will also incur high cost in maintaining those beliefs. In this paper, we demonstrate that we can choose a minimal, but sufficient, space of mental models by combining models that action or utility equivalence. We illustrate our framework using the two-tiger game and provide empirical results by showing the minimal mental model spaces that it generates.
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Kagaya, H. Matsuo, und T. Soma. „The Influence of the Compression Effect on the Phase Diagrams of Si–Ge System“. physica status solidi (b) 144, Nr. 2 (01.12.1987): 549–56. http://dx.doi.org/10.1002/pssb.2221440213.
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Hsieh, Yen-Hao, und Soe-Tsyr Yuan. „Using System Dynamics to Analyze Customer Experience Design“. International Journal of Service Science, Management, Engineering, and Technology 1, Nr. 3 (Juli 2010): 84–99. http://dx.doi.org/10.4018/jssmet.2010070105.
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Today, customer experience design is an emerging research direction in the experience economy where good customer experiences can lead service providers to achieve their business goals. Customer expectation, another key point for designing service experiences, affects how customers really feel during service experience delivery, while service operation is another important factor must be taken into account. System dynamics, as an analytic tool, can provide designers with a different way of thinking by integrating these factors for customer experience design. Accordingly, this study not only models the process of customer experience design by using causal loop diagrams and stock and flow diagrams, but also analyzes how the feedback and time delay factors influence customer experience design based on the simulation results of system dynamics. According to the macro viewpoint of system dynamics, this paper analyzes these important factors within customer experience design.
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He, Minjia, Shuo Li, Jinjin Wang, Zhenjun Lin und Shuang Liu. „The Nonsmooth Vibration of a Relative Rotation System with Backlash and Dry Friction“. Discrete Dynamics in Nature and Society 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/7064590.
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We investigate a relative rotation system with backlash and dry friction. Firstly, the corresponding nonsmooth characters are discussed by the differential inclusion theory, and the analytic conditions for stick and nonstick motions are developed to understand the motion switching mechanism. Based on such analytic conditions of motion switching, the influence of the maximal static friction torque and the driving torque on the stick motion is studied. Moreover, the sliding time bifurcation diagrams, duty cycle figures, time history diagrams, and the K-function time history diagram are also presented, which confirm the analytic results. The methodology presented in this paper can be applied to predictions of motions in nonsmooth dynamical systems.
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Curbelo, Fabiola Dias da Silva, Alfredo Ismael Curbelo Garnica, Beatriz Sales Cavalcanti Nascimento, Giovanna Lais Rodrigues Leal, Tarsila Melo Tertuliano und Raphael Ribeiro da Silva. „Influence of the oleic phase and co-surfactant addition in non-ionic microemulsified systems“. Research, Society and Development 10, Nr. 2 (28.02.2021): e58410212902. http://dx.doi.org/10.33448/rsd-v10i2.12902.
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Microemulsion is a thermodynamically stable dispersion consisting of an aqueous and an organic phases, both stabilized by surfactant molecules and when in need, co-active surfactant. The nature and structure of these components are essential in the formulation of microemulsified systems. For this, the construction of phase diagrams can be a fundamental tool to characterize the ideal experimental conditions for the existence and operation of microemulsions. Thus, the present work had as objective to obtain a comparison between microemulsions with different compositions through the construction of ternary diagrams, aiming to achieve the most stable system. To produce microemulsified systems, a non-ionic surfactant (Ultranex NP 60), a co-surfactant (Isopropyl Alcohol), two organic phases (pine oil and castor oil) and an aqueous phase (glycerin solution) were used. Also complementing the study, rheological tests of the oleic phases were accomplished, as well as their thermogravimetric analysis. The focus of the reached ternary diagrams was to find the system with the largest Winsor type IV region (microemulsion). It was verified this region had a significant increase by the addition of the co-surfactant in the medium and using a vegetable oil, such as pine oil, since it promotes strong surfactant-oil interactions on the interface.
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Mîţiu, A. Mihaela, Daniel Constantin Comeagă und Octavian G. Donţu. „The Control of Vibration Transmissibility Using an Electrodynamic Actuator – Passive Solution“. Applied Mechanics and Materials 436 (Oktober 2013): 158–65. http://dx.doi.org/10.4028/www.scientific.net/amm.436.158.
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Starting with the mathematical model of a simple electro-mechanical system with 1 DOF, are identified the electrical parameters which may influence the efficiency of control of the system transmissibility using an electrodynamic actuator. Based on simulation of system operation and determination of transmissibility are obtained Bode diagrams and diagrams that shows the maximum variation of the resonance frequency of the system when varying the electrical parameters of the actuator. In the paper is indicated the limits of the theoretical and practical technical solutions to control mechanical transmissibility of a system using an electrodynamic actuator.
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Yao, Lingling, Zhuo Meng, Jianqiu Bu und Yize Sun. „Investigation of Nonlinear Characteristics of a Gear Transmission System in a Braiding Machine with Multiple Excitation Factors“. Shock and Vibration 2020 (25.03.2020): 1–20. http://dx.doi.org/10.1155/2020/2747204.
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In this study, we attempt to analyze the influence of different excitation factors on the dynamic behavior of a gear transmission system in a braiding machine. In order to observe nonlinear characteristics, a mathematical model is established with a six-degrees-of-freedom gear system for consideration of multiple excitation factors. Iterative results are used to study the nonlinear characteristics of the gear system with respect to contact temperature, varying levels of friction, and disturbance of yarn tension using bifurcation diagrams, maximum Lyapunov exponents, phase diagrams, Poincare maps, and the power spectrum. The numerical results show that excitation factors such as temperature and surface friction, among others, have considerable influence on the nonlinear characteristics of the gear system in a braiding machine, and the model is evaluated to show the key regions of sensitivity. The analysis of associated parameters can be helpful in the design and control of braiding machines.
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Rusinek, Rafal, Marian Wiercigroch und Pankaj Wahi. „Influence of Tool Flank Forces on Complex Dynamics of Cutting Process“. International Journal of Bifurcation and Chaos 24, Nr. 09 (September 2014): 1450115. http://dx.doi.org/10.1142/s0218127414501156.
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We study complex dynamics of a cutting process, a recently developed frictional model of cutting process in [Rusinek et al., 2014] to gain better insight into the mechanics of frictional chatter and the factors affecting it. The new model takes into account the forces acting on the tool face as well as on the tool flank. We first present nonlinear dynamic behavior using bifurcation diagrams for nominal cutting depth and cutting velocity as the bifurcation parameters. Finally, the influence of the various forces on the tool flank on the system dynamics has been systematically studied. This has been performed by comparing the bifurcation diagrams with and without the forces on the flank. These flank forces have been found to largely have a stabilizing effect. These forces however increase the complexity of the solutions and are responsible for some instabilities in the low cutting velocity regime.
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Hu, Haiqing, Bingqiang Liu und Tao Shen. „Intelligent reasoning and management decision making with grey rough influence diagrams“. International Journal of Intelligent Computing and Cybernetics 9, Nr. 4 (14.11.2016): 336–53. http://dx.doi.org/10.1108/ijicc-03-2016-0012.
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Purpose Influence diagrams (IDs) have been widely applied as a form of knowledge expression and a decision analysis tool in the management and engineering fields. Relationship measurements and expectation values are computed depending on probability distributions in traditional IDs, however, most information systems in the real world are nondeterministic, and data in information tables can be interval valued, multiple valued and even incomplete. Consequently, conventional numeric models of IDs are not suitable for information processing with respect to imprecise data whose boundaries are uncertain. The paper aims to discuss these issues. Design/methodology/approach The grey system theory and rough sets have proved to be effective tools in the data processing of uncertain information systems, approximate knowledge acquisition and representation are also the objectives in intelligent reasoning and decision analysis. Hence, this study proposes a new mathematical model by combining grey rough sets with IDs, and approximate measurements are used instead of probability distribution, an implicational relationship is utilized instead of an indiscernible relationship, and all of the features of the proposed approach contribute to deal with uncertain problems. Findings The focus of this paper is to provide a more comprehensive framework for approximate knowledge representation and intelligent decision analysis in uncertain information systems and an example of decision support in product management systems with the new approach is illustrated. Originality/value Collaboration of IDs and grey rough sets is first proposed, which provides a new mathematical and graphical tool for approximate reasoning and intelligent decision analysis within interval-valued information systems.
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Gajek, Z., und R. Lemański. „Influence of the inter-ion interaction on the phase diagrams of the 1D Falicov–Kimball system“. Journal of Magnetism and Magnetic Materials 272-276 (Mai 2004): E691—E692. http://dx.doi.org/10.1016/j.jmmm.2003.12.1263.
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Ehlen, Georg J., Hai Feng Wang und Dieter M. Herlach. „Concentration Dependent Growth Velocities in Undercooled Al-Rich Al-Ni Alloy Systems“. Materials Science Forum 790-791 (Mai 2014): 485–90. http://dx.doi.org/10.4028/www.scientific.net/msf.790-791.485.
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Dendrite growth velocity V as a function of undercooling on the Al-rich side of the Al-Ni system has recently been measured by electromagnetic levitation. The results have shown an anomalous behaviour, which so far cannot be theoretically described. The present work uses two simplified qualitative models of sharp interface theory, one of them treating the forming AlNi (B2) phase as a solid-solution, one treating it as an intermetallic phase, to investigate the influence of the phase diagram on the growth velocities. The results imply that the concentration dependent growth behaviour is a superposition of at least two effects: 1) A strong decrease of the total growth velocitiy level for increasing Al concentrations. 2) An increase of growth velocities with increase of Al concentration at medium and low undercoolings. The present work is able to explain the first effect, namely the concentration dependent reduction of velocities. Results are compared to experimental data. In both models the properties of the phase diagram lead to an increase of the constitutional undercooling ΔTc when the Al content increases. This reduces the fraction left for kinetic undercooling ΔTk, which is responsible for interface migration and which determines the growth velocity. Neither of the models can reproduce the second effect.
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CURTIS, NEVILLE J., und PETER J. DORTMANS. „A DYNAMIC CONCEPTUAL MODEL TO EXPLORE TECHNOLOGY-BASED PERTURBATIONS TO A COMPLEX SYSTEM: THE LAND FORCE“. Asia-Pacific Journal of Operational Research 21, Nr. 04 (Dezember 2004): 463–85. http://dx.doi.org/10.1142/s0217595904000345.
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Conceptual models are the critical first step to gaining distilled insights of complex systems. We use influence diagrams to link intuitive measures for Land Force actions with the inputs of the environment, and friendly and threat force actions. This approach provides a rich semiquantitative model that allows exploration of the effect of perturbation introduced through the adoption of enhanced equipment, innovative operational concepts, or novel technology concepts. We have built a construct for the Army based upon a set of influence diagrams for the skills of: engagement; information collection; sustainment; communication; protection; movement; and decision making. These produce mental maps that link military technologies, desired effects, and higher-level outcomes. Thus, there is a gradation of type within the influence diagram with position the key to the nature of the variable. In this paper we describe these models and how we use them to deduce likely future military concepts through "what if" contemplations of possible technology or environmental changes. In reverse, this process advises on the criticality of the constituent components. Inter-relationships between various skills and issues associated with balancing requirements between these will be highlighted. This work thus leads to further distillation-like simulations such as agent-based modeling.
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Przondziono, Joanna, und Witold Walke. „Influence of the Type of Medical Sterilisation on Electrochemical Properties of Passive Layer Created on X10CrNi 18-8 Steel“. Solid State Phenomena 212 (Dezember 2013): 141–44. http://dx.doi.org/10.4028/www.scientific.net/ssp.212.141.
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The study presents results of impedance tests performed for wires made of X10CrNi 18-8 steel after electrochemical polishing and chemical passivation, subject to medical sterilisation with pressurised water steam or ethylene oxide. In order to determine the impact of sterilising agent on electrochemical characteristics of the passive layer, impedance measurements were made. Measurements were made with application of measurement system Auto Lab PGSTAT 302N equipped with FRA2 (Frequency Response Analyser) module. Impedance spectra of the system were determined in the tests and data obtained in the measurement was matched to the equivalent system. It made the ground for determination of numerical values of resistance and capacitance of the analysed systems. Impedance spectra of the tested system are presented in the form of Nyquist diagrams for various values of frequency, and as Bode diagrams. On the ground of performed test it was explicitly proved that application of steam sterilisation and sterilisation with ethylene oxide of wires made of X10CrNi 18-8 steel after chemical passivation used for urological guide wires has a favourable impact on their electrochemical characteristics.
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Wang, Huihai, Kehui Sun und Shaobo He. „Characteristic Analysis and DSP Realization of Fractional-Order Simplified Lorenz System Based on Adomian Decomposition Method“. International Journal of Bifurcation and Chaos 25, Nr. 06 (15.06.2015): 1550085. http://dx.doi.org/10.1142/s0218127415500856.
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By adopting Adomian decomposition method, the fractional-order simplified Lorenz system is solved and implemented on a digital signal processor (DSP). The Lyapunov exponent (LE) spectra of the system is calculated based on QR-factorization, and it accords well with the corresponding bifurcation diagrams. We analyze the influence of the parameter and the fractional derivative order on the system characteristics by color maximum LE (LEmax) and chaos diagrams. It is found that the smaller the order is, the larger the LEmax is. The iteration step size also affects the lowest order at which the chaos exists. Further, we implement the fractional-order simplified Lorenz system on a DSP platform. The phase portraits generated on DSP are consistent with the results that were obtained by computer simulations. It lays a good foundation for applications of the fractional-order chaotic systems.
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Gorbacheva, O. M., und A. S. Borovsky. „System Analysis of the State of Automation of Technological Processes for Cleaning Used Oils“. Ecology and Industry of Russia 22, Nr. 5 (23.05.2018): 54–58. http://dx.doi.org/10.18412/1816-0395-2018-5-54-58.
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Based on the system analysis using IDF0 diagrams, functional models of existing technical systems for cleaning used oil have been constructed. The influence of the parameters of the technological process on the time of its flow and the degree of purification of the used oil are described. After studying the influence of the parameters of the technological process of cleaning used oil and analyzing the existing automated technical oil purification systems, the necessity of developing a new automated technical system for cleaning the waste oil is substantiated, in which the parameters of the process that have not been considered previously will be monitored.
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Peters, G. J. „The Hα Emitting Regions of the Accretion Disks in Algols“. International Astronomical Union Colloquium 107 (1989): 9–22. http://dx.doi.org/10.1017/s0252921100087637.
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AbstractThe circumstellar plasma that produces Hα emission in Algol binaries has been investigated using phase-resolved, high dispersion data acquired from CCD and image tube detectors. Results are summarized in this paper, including discussions of the disk geometry and size, asymmetry in the distribution of material, long-term or non-phase dependent variability, mass outflow, the mean electron density, and how the latter properties vary with the system’s period or location in the r - q diagram. Five systems which display permanent emission with periods ranging from 4.5 to 261 days (SW Cyg, UX Mon, TT Hya, AD Her, and RZ Oph) are intercompared. If P < 4.5 days, no permanent disks are observed, while if P > 6 days, stable disks with only slight long-term variations in their Hα brightness are seen. The most variable systems appear to be those in the 5 - 6 day range, but the star’s position in the r - q diagram has the largest influence on its behavior. The trailing side of the accretion disk, where the gas stream impacts the inner disk, is usually brighter, and the leading side is often times more extended. The disk extends out to at least 95%of the Roche surface of the primary and is highly flattened (≤Rp). Mass outflow near phase 0.5 is commonplace.
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Zhao, Jiang Lin, und Min Zhao. „Modeling the Role of Toxic Substances in a Phytoplankton-Toxic Phytoplankton-Zooplankton System“. Advanced Materials Research 726-731 (August 2013): 1600–1603. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.1600.
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In this paper, a mathematical model has been proposed, which consists of three variables: non-toxic phytoplankton (NTP), toxin producing phytoplankton (TPP) and zooplankton. In this model, an Monod- Haldane functional response is utilized to identify the grazing process of zooplankton due to the phytoplankton toxicity. The product of square of TPP density with square of NTP density is to depict the allelopathic influence on NTP. Numerical analysis indicates that the phytoplankton toxicity has a significant influence on the dynamical complexity and species biomass level through bifurcation diagrams. All these results are expected to be of significance in exploration of the dynamical complexity of ecosystems.
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Watson, Michael E., Christina F. Rusnock, Michael E. Miller und John M. Colombi. „Performing System Tradeoff Analyses Using Human Performance Modeling“. Proceedings of the Human Factors and Ergonomics Society Annual Meeting 60, Nr. 1 (September 2016): 734. http://dx.doi.org/10.1177/1541931213601168.
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Humans perform critical functions in nearly every system, making them vital to consider during system development. Human Systems Integration (HSI) would ideally permit the human’s impact on system performance to be effectively accounted for during the systems engineering (SE) process, but effective processes are often not applied, especially in the early design phases. Failure to properly account for human capabilities and limitations during system design may lead to unreasonable expectations of the human. The result is a system design that makes unrealistic assumptions about the human, leading to an overestimation of the human’s performance and thus the system’s performance. This research proposes a method of integrating HSI with SE that allows human factors engineers to apply Systems Modeling Language (SysML) and human performance simulation to describe and communicate human and system performance. Using these models, systems engineers can more fully understand the system’s performance to facilitate design decisions that account for the human. A scenario is applied to illustrate the method, in which a system developer seeks to redesign an example system, Vigilant Spirit, by incorporating system automation to improve overall system performance. The example begins by performing a task analysis through physical observation and analysis of human subjects’ data from 12 participants employing Vigilant Spirit. This analysis is depicted in SysML Activity and Sequence Diagrams. A human-in-the-loop experiment is used to study performance and workload effects of humans applying Vigilant Spirit to conduct simulated remotely-piloted aircraft surveillance and tracking missions. The results of the task analysis and human performance data gathered from the experiment are used to build a human performance model in the Improved Performance Research Integration Tool (IMPRINT). IMPRINT allows the analyst to represent a mission in terms of functions and tasks performed by the system and human, and then run a discrete event simulation of the system and human accomplishing the mission to observe the effects of defined variables on performance and workload. The model was validated against performance data from the human-subjects’ experiment. In the scenario, six different scan algorithms, which varied in terms of scan accuracy and speed, were simulated. These algorithms represented different potential system trades as factors such as various technologies and hardware architectures could influence algorithm accuracy and speed. These automation trades were incorporated into the system’s block definition (BDD), requirements, and parametric SysML diagrams. These diagrams were modeled from a systems engineer’s perspective; therefore they originally placed less emphasis on the human. The BDD portrayed the structural aspect of Vigilant Spirit, to include the operator, automation, and system software. The requirements diagram levied a minimum system-level performance requirement. The parametric diagram further defined the performance and specification requirements, along with the automation’s scan settings, through the use of constraints. It was unclear from studying the SysML diagrams which automation setting would produce the best results, or if any could meet the performance requirement. Existing system models were insufficient by themselves to evaluate these trades; thus, IMPRINT was used to perform a trade study to determine the effects of each of the automation options on overall system performance. The results of the trade study revealed that all six automation conditions significantly improved performance scores from the baseline, but only two significantly improved workload. Once the trade study identified the preferred alternative, the results were integrated into existing system diagrams. Originally system-focused, SysML diagrams were updated to reflect the results of the trade analysis. The result is a set of integrated diagrams that accounts for both the system and human, which may then be used to better inform system design. Using human performance- and workload-modeling tools such as IMPRINT to perform tradeoff analyses, human factors engineers can attain data about the human subsystem early in system design. These data may then be integrated into existing SysML diagrams applied by systems engineers. In so doing, additional insights into the whole system can be gained that would not be possible if human factors and systems engineers worked independently. Thus, the human is incorporated into the system’s design and the total system performance may be predicted, achieving a successful HSI process.
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Peng, Guangya, Fuhong Min und Enrong Wang. „Circuit Implementation, Synchronization of Multistability, and Image Encryption of a Four-Wing Memristive Chaotic System“. Journal of Electrical and Computer Engineering 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/8649294.
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The four-wing memristive chaotic system used in synchronization is applied to secure communication which can increase the difficulty of deciphering effectively and enhance the security of information. In this paper, a novel four-wing memristive chaotic system with an active cubic flux-controlled memristor is proposed based on a Lorenz-like circuit. Dynamical behaviors of the memristive system are illustrated in terms of Lyapunov exponents, bifurcation diagrams, coexistence Poincaré maps, coexistence phase diagrams, and attraction basins. Besides, the modular equivalent circuit of four-wing memristive system is designed and the corresponding results are observed to verify its accuracy and rationality. A nonlinear synchronization controller with exponential function is devised to realize synchronization of the coexistence of multiple attractors, and the synchronization control scheme is applied to image encryption to improve secret key space. More interestingly, considering different influence of multistability on encryption, the appropriate key is achieved to enhance the antideciphering ability.
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Saha, Debasish, Karthik R. Peddireddy, Jürgen Allgaier, Wei Zhang, Simona Maccarrone, Henrich Frielinghaus und Dieter Richter. „Amphiphilic Comb Polymers as New Additives in Bicontinuous Microemulsions“. Nanomaterials 10, Nr. 12 (02.12.2020): 2410. http://dx.doi.org/10.3390/nano10122410.
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It has been shown that the thermodynamics of bicontinuous microemulsions can be tailored via the addition of various different amphiphilic polymers. In this manuscript, we now focus on comb-type polymers consisting of hydrophobic backbones and hydrophilic side chains. The distinct philicity of the backbone and side chains leads to a well-defined segregation into the oil and water domains respectively, as confirmed by contrast variation small-angle neutron scattering experiments. This polymer–microemulsion structure leads to well-described conformational entropies of the polymer fragments (backbone and side chains) that exert pressure on the membrane, which influences the thermodynamics of the overall microemulsion. In the context of the different polymer architectures that have been studied by our group with regards to their phase diagrams and small-angle neutron scattering, the microemulsion thermodynamics of comb polymers can be described in terms of a superposition of the backbone and side chain fragments. The denser or longer the side chain, the stronger the grafting and the more visible the brush effect of the side chains becomes. Possible applications of the comb polymers as switchable additives are discussed. Finally, a balanced philicity of polymers also motivates transmembrane migration in biological systems of the polymers themselves or of polymer–DNA complexes.
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Shen, Shuang Juan, Li Qin Jiang, Ke Hua Zhong, Zhi Gao Chen und Zhi Gao Huang. „The Magnetic Properties of Mixed Ferrimagnetic Spin System“. Advanced Materials Research 148-149 (Oktober 2010): 1036–41. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.1036.
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Based on Monte Carlo (MC) simulation, the magnetization behavior of mixed ferrimagnetic spin system with single-ion anisotropy under external field is investigated. It is assumed that the element of the mixed system is composed of spin-1 and spin-3/2 by turns. The simulated results indicate that there exist the magnetization curves at the ground state on the one-dimensional spin chain, two-dimensional spin system as well as three-dimensional spin system. It found that the size, anisotropy constant and spin configurations influence evidently the magnetic properties of the mixed system. Moreover, the magnetic plateaus and the phase diagrams of the systems can be well interpreted in terms of the simple calculation of energy.
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Liu, Ran Hui, und Qing Quan Hu. „The Influence of Excitation Frequency on Dynamical Behaviors of Atomic Force Microscope“. Advanced Materials Research 518-523 (Mai 2012): 3891–95. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3891.
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This paper deals with dynamical behaviors of Atomic Force Microscope in the different excitation frequency. By using Poincare maps, phase trajectory, Lyapunov exponent, bifurcation diagram, the dynamical behaviors are identified based on the numerical solutions of the governing equations. Bifurcation diagrams are presented in the case that the excitation amplitude increases while other parameters are fixed. Numerical simulations indicate that periodic and chaotic motions occur in the system. At the same, when chaotic motions occur, the excitation amplitude decrease as the excitation frequency increases.
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Wang, Z., Y. Sui, A. V. Salsac, D. Barthès-Biesel und W. Wang. „Path selection of a spherical capsule in a microfluidic branched channel: towards the design of an enrichment device“. Journal of Fluid Mechanics 849 (18.06.2018): 136–62. http://dx.doi.org/10.1017/jfm.2018.414.
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We computationally study the motion of an initially spherical capsule flowing through a straight channel with an orthogonal lateral branch, using a three-dimensional immersed-boundary lattice-Boltzmann method. The capsule is enclosed by a strain-hardening membrane and contains an internal fluid of the same viscosity as the fluid in which it is suspended. Our primary focus is to study the influence of the geometry of the side branch on the capsule path selection. Specifically, we consider the case where the side branch cross-section is half that of the straight channel and study various bifurcation configurations, where the branch is rectangular or square, centred or not on the straight channel axis. The capsule is initially centred on the axis of the straight channel. We impose the flow rate split ratio between the two downstream branches of the bifurcation. We summarise the results obtained for different capsule-to-channel size ratios, flow Reynolds number $Re$ (based on the parent channel size and average flow speed) and capsule mechanical deformability (as measured by the capillary number) in phase diagrams giving the critical flow rate split ratio above which the capsule flows into the side branch. A major finding is that, at equal flow rate split between the two downstream branches, the capsule will enter a branch which is narrow in the spanwise direction, but will not enter a branch which is narrow in the flow direction. For $Re\leqslant 5$, this novel intriguing phenomenon primarily results from the background flow, which is strongly influenced by the side branch geometry. For higher values of $Re$, the capsule relative size and deformability also play specific roles in the path selection. The capsule trajectory does not always obey the classical Fung’s bifurcation law, which stipulates that a particle (in Fung’s case, a red blood cell) enters the bifurcation branch with the highest flow rate. We also consider the same branched channels operating under constant pressure drop conditions and show that such systems are difficult to control due to the transient additional pressure drop caused by the capsule. The present results obtained for dilute systems open new perspectives on the design of microfluidic systems, with optimal channel geometries and flow conditions to enrich cell and particle suspensions.
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Ren, Jingli, und Xueping Li. „Bifurcations in a Seasonally Forced Predator–Prey Model with Generalized Holling Type IV Functional Response“. International Journal of Bifurcation and Chaos 26, Nr. 12 (November 2016): 1650203. http://dx.doi.org/10.1142/s0218127416502035.
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A seasonally forced predator–prey system with generalized Holling type IV functional response is considered in this paper. The influence of seasonal forcing on the system is investigated via numerical bifurcation analysis. Bifurcation diagrams for periodic solutions of periods one and two, containing bifurcation curves of codimension one and bifurcation points of codimension two, are obtained by means of a continuation technique, corresponding to different bifurcation cases of the unforced system illustrated in five bifurcation diagrams. The seasonally forced model exhibits more complex dynamics than the unforced one, such as stable and unstable periodic solutions of various periods, stable and unstable quasiperiodic solutions, and chaotic motions through torus destruction or cascade of period doublings. Finally, some phase portraits and corresponding Poincaré map portraits are given to illustrate these different types of solutions.
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Liu, Gui Zhen, Ying Yu und Bang Chun Wen. „Nonlinear Dynamics Analysis of Excitation Frequency under the Influence of the Rotor-Stator-Bearing System with Rub-Impact Fault“. Advanced Materials Research 952 (Mai 2014): 169–75. http://dx.doi.org/10.4028/www.scientific.net/amr.952.169.
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Established the unsteady oil-film force with rub-impact fault of rotor-stator-bearing system mechanical models by using Lagrange equation, Application of numerical analysis to study it, concluded that the rotor system in frequency as the only incentive system control parameters of orbit and bifurcation diagrams; analysis of the nonlinear behavior of the response of the system and the failure mechanism, provide a theoretical basis for the safe operation of the rotor system and fault diagnosis. The results show that, when the excitation frequency as the only control parameters, the system exist periodic motion, quasi periodic motion and chaotic motion etc abundant nonlinear phenomena.
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Sun, Ye, Chunrui Zhang und Yuting Cai. „Hopf-Pitchfork Bifurcation in a Symmetrically Conservative Two-Mass System with Delay“. Zeitschrift für Naturforschung A 73, Nr. 6 (27.06.2018): 511–19. http://dx.doi.org/10.1515/zna-2017-0443.
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AbstractA symmetrically conservative two-mass system with time delay is considered here. We analyse the influence of interaction coefficient and time delay on the Hopf-pitchfork bifurcation. The bifurcation diagrams and phase portraits are then obtained by computing the normal forms for the system in which, particularly, the unfolding form for case III is seldom given in delayed differential equations. Furthermore, we also find some interesting dynamical behaviours of the original system, such as the coexistence of two stable non-trivial equilibria and a pair of stable periodic orbits, which are verified both theoretically and numerically.
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Li, Meina, Yi Zhang, Yang Lu, Wenya Yu, Xin Nong und Lulu Zhang. „Factors influencing two-way referral between hospitals and the community in China: A system dynamics simulation model“. SIMULATION 94, Nr. 9 (14.11.2017): 765–82. http://dx.doi.org/10.1177/0037549717741349.
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Background: Two-way referrals between hospitals and community healthcare systems (CHSs) are important for optimizing the distribution of medical resources and enabling resource sharing, but referrals are always from CHSs to hospitals. A referral from the hospital to the community is rare in China; this has a highly negative impact on the long-term development of the Chinese health services. The aim of this study was to address influence factors in hospital–community referrals. Methods: We constructed a system dynamics model to address the problem of the two-way referral between hospitals and CHSs and identified potential countermeasures and possible solutions. The Vensim DSS program was used to construct a system dynamics model to represent the problem through model description, causal loop diagrams, and stock and flow diagrams. Results: The model was used to perform intervention experiments, in which the influence on all the sectors of referrals could be observed by changing the system parameters. The experimental results showed a greater difference in medical costs between hospitals and CHSs, more investments to CHSs, higher levels of medical insurance of CHSs, and more referrals from hospitals to CHSs. Conclusions: The system can widen the price gap between hospitals and CHSs, increase information flow, improve medical insurance level of CHSs, and elevate the current level of CHSs through enabling two-way referral between hospitals and CHSs.
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Rod, Jan Ketil. „How The Monosemic Graphics Go Polysemic“. Cartographic Perspectives, Nr. 38 (01.03.2001): 7–18. http://dx.doi.org/10.14714/cp38.792.
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This paper is a reflection on the semiological tradition after Saussure. The focus here is cartographic. In 1967 Jacques Bertin presented the semiology of graphics, which has had an extensive influence on cartography. Bertin claimed graphics (diagrams, networks and maps) to be a monosemic sign system because graphics transcribe relationships that are previously defined in a data table. This premise is critically revisited regarding maps, resulting in the conclusion that diagrams and networks might be monosemic representations while statistical maps cannot. Polysemy is introduced in statistical mapping because the plan possesses influencing properties on the transcribed meaning, which are not a priori defined in the data table.
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Geisler, Tomasz. „Free vibration analysis of a DST-0285 truck crane considering changes in the system load configuration“. MATEC Web of Conferences 157 (2018): 03005. http://dx.doi.org/10.1051/matecconf/201815703005.
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A model of a truck crane, consisting of the fundamental units of the crane, is presented in this paper. The finite element method and a COSMOS/M package were applied to perform the modelling. Research into the influence of a change in the crane radius and load location on changes in the chosen free vibrations was carried out using the built models. Diagrams containing changes in the frequency of vibrations for chosen values of the crane radius and the load are presented and conclusions are drawn.
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HYCH, О., M. RASTORHYIEVA und О. ZAKORA. „STUDY OF THE CARDING PROCESS INFLUENCE ON THE GEOMETRIC CHARACTERISTICS OF HEMP FIBER“. HERALD OF KHMELNYTSKYI NATIONAL UNIVERSITY 297, Nr. 3 (02.07.2021): 173–80. http://dx.doi.org/10.31891/2307-5732-2021-297-3-173-180.
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The article analyzes the possibility of processing imported hemp raw materials to obtain household textiles using domestic technologies for processing best fibers. The choice of the carding process is justified as a mechanical effect on the geometric characteristics of hemp. A preliminary visual analysis of samples of hemp fibers, which is imported by a domestic enterprise in order to obtain yarn using a carded spinning system, has been carried out. As a result of the analysis of morphometric characteristics, it was found that the resulting fiber is hemp cottonin. The length and thickness of cottonin vary considerably. Such dimensional characteristics do not allow using it for the manufacture of household yarn. To further break down the complex hemp fibers and reduce their length, a carding process is applied. The study of the effect of the carding process was carried out while implementing five carding cycles on a laboratory fiber mixer, which is an imitation of the carding process on carding equipment in a production environment. After each carding cycle, a card canvas is formed, in which the fibers are evenly mixed and oriented in the longitudinal direction. Sizing of hemp fibers occurs after each carding cycle. According to the dimensional characteristics, staple and modal diagrams of the length distribution and diagrams of the diameter distribution of hemp fibers were constructed. It was found that as a result of the carding process, the average length and thickness of hemp fibers decreased significantly while maintaining the normalized breaking load. But at the same time, the proportion of long fibers remains and a rather high linear density of the fibers remains, which does not allow them to be processed into yarn using a carded spinning system. It is recommended that you continue with the mechanical processing process or use carded hemp fiber to make yarn using the machine’s wool spinning system.
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Nepomnyashchy, Alexander A., und Ilya B. Simanovskii. „The influence of two-dimensional temperature modulation on nonlinear Marangoni waves in two-layer films“. Journal of Fluid Mechanics 846 (11.05.2018): 944–65. http://dx.doi.org/10.1017/jfm.2018.304.
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The nonlinear dynamics of waves generated by the deformational oscillatory Marangoni instability in a two-layer film under the action of a two-dimensional temperature modulation on the solid substrate is considered. A system of long-wave equations governing the deformations of the upper surface and the interface between the liquids is presented. The long-wave approach is applied. The nonlinear simulations reveal the existence of different dynamic regimes, including stationary, time-periodic and quasi-periodic flows. The general diagrams of the flow regimes are constructed.
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Zhang, YF, S. Zhang, FX Liu, C. Zhou, YJ Lu und N. Müller. „Motion analysis of a rotor supported by self-acting axial groove gas bearing system with double time delays“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, Nr. 16 (12.02.2014): 2888–99. http://dx.doi.org/10.1177/0954406214523581.
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A rotor system with double time delays supported by the high-speed self-acting gas-lubricated bearings with three-axial grooves is modeled to implement active delay control of the system. The differential transformation method is employed to solve the time-dependent compressible gas Reynolds equation due to its rapid convergence rate and minimal calculation error. Based on the precise integration method, a calculation method is proposed to analyze the dynamic responses of a gas bearing-rotor nonlinear system with time delays. The motion analysis of the self-acting gas-lubricated bearing-rotor system with double time delays is implemented by the orbit diagrams, the time series, and the phase diagrams. The influence of time delays and feedback control gains on the dynamic responses of the bearing-rotor nonlinear system is analyzed. The numerical results show that the amplitude of the responses of the system with time delays control is reduced, the motion is more stable and good control effect is achieved when the chosen feedback control gains match the time delays of the bearing-rotor system.
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CISEK, Jerzy. „The influence of non-cooled exhaust gas recirculation on the indicator diagrams and heat release parameters in diesel engine cylinder“. Combustion Engines 171, Nr. 4 (01.11.2017): 283–88. http://dx.doi.org/10.19206/ce-2017-449.
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This paper presents the results of the diesel engine research on the indicator and heat realized diagrams for VW 1.9 TDI working in 2 modes: with standard, non-cooled EGR system, and without this system. All of measurement was carried out on the some engine speed – 2000 rpm (speed of maximum engine torque) and various engine load. Some of the analyzed parameters were read directly from the measurement systems (e.g. indicator diagrams) or engine controller (e.g. start of injection) and the rest of them had to be calculated. The calculation of rate of heat release (dQ/dα) was based on the well-known mathematical model. When the exhaust gas recirculation valve is open, the maximum of combustion pressure and rate of maximum kinetic heat release (dQk/dα)max are smaller than when the valve is closed. These facts are connected with the shorter self-combustion delay for engine working with EGR. But this is also associated with reduction of the rate of maximum diffusion heat release (dQd/dα)max, which means that more particulates (PM) are excreted into the atmosphere. This fact explains e.g. significantly higher smog of exhaust gases for diesel engine which works with EGR system. The analysis results show that exhaust gas recirculation system slightly deteriorates the energetic parameters of VW 1.9 TDI engine, but, at the same time, significantly reduces the level of toxic nitrogen oxides in exhaust gases
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Muscalu, Gheorghe, Gheorghe Voicu, Adriana Istudor und Paula Tudor. „Bread Dough Rheological Behavior Under the Influence of the Geometry of the Kneading Arms“. Revista de Chimie 71, Nr. 9 (05.09.2020): 295–307. http://dx.doi.org/10.37358/rc.20.9.8340.
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The main objective of this study is validation of a proposed mathematical model for the estimation of the influence of kneading arms geometries on rheological properties of dough. Two types of kneading arms are studied, both mounted on the same industrial kneader type. A tridimensional numerical simulation for dough kneading is used for obtaining the Eddy viscosity values, which were introduced in a mathematical model for calculation of the dough�s resistant torque at the kneading arms, at 15 seconds time intervals. Real time torque diagrams developed by the kneading arms, were traced using a system for data acquisition and dough kneading control (SOPF), developed by BioTechnologiCreativ Company. These diagrams were used for mathematical model validation using the comparison between the torque values measured in real time and the ones obtained using the mathematical model, in which was introduced the Eddy viscosity value obtained with the 3D simulation. The obtained results have very similar values. With this study it is possible to predict the rheological behavior of dough during kneading process. Anticipation of the kneading diagram form can be helpful in the optimization of the entire technological process and the obtaining of dough with uniform consistency and optimal development during the stages of the manufacturing process.
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Peng, Jian Kui, Jian Ning Yu, Li Zhang und Ping Hu. „Study on Synchronization of the Centrifugal Flywheel Governor System“. Applied Mechanics and Materials 433-435 (Oktober 2013): 21–29. http://dx.doi.org/10.4028/www.scientific.net/amm.433-435.21.
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In this paper, the dynamical behaviors of the centrifugal flywheel governor with external disturbance is studied and it has abundant nonlinear behavior.The influence of system parameter is discussed by Lyapunov exponents spectrum and global bifurcation diagram, which accurately portray the partial dynamic behavior of the centrifugal flywheel governor. The routes to chaos are analyzed using Poincaré sections, which are found to be more complex . Periodic and chaotic motions can be clearly distinguished by Poincaré sections, bifurcation diagrams and Lyapunov exponents. Then, the paper proposes coupledfeedback control and adaptive control methods to achieve the chaotic the centrifugal flywheel governor system synchronization, the numerical simulation was provided in order to show the effectiveness of coupled feedback control and adaptive control methods for the synchronization of the chaotic nonautonomous centrifugal flywheel governor system.
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Chiu, Yi Jui, Dar Zen Chen und Chia Hao Yang. „Influence on Coupling Vibration of Rotor System with Grouped Blades due to Mistuned Lacing Wire“. Applied Mechanics and Materials 101-102 (September 2011): 1119–25. http://dx.doi.org/10.4028/www.scientific.net/amm.101-102.1119.
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The influence on coupling vibrations among shaft-torsion and blade-bending coupling vibrations of a rotor system with grouped blades was investigated analytically. The natural frequencies and the mode shapes of the system were solved with five- and six-blade cases used as examples. First, numerical results showed how the natural frequencies varied with the wire stiffness and the lacing wire mistuned. The diagrams of the coupling mode shapes were drawn. From the results, it was found that lacing wire did not affect the SB (shaft-blades) coupling modes, but the BB (inter-blades) modes were indeed affected by the lacing wire. At wire stiffness k*=10, the repeated BB modes split into more distinct modes. The BB modes were of (N-1) / 2 and N / 2 multiplicity for odd and even numbered blades. When the system has a mistuned lacing wire, it splits the BB modes and will once more have (N-1) frequencies. In the rotation effect, whatever tuned or mistuned, the lacing wires did not affect the instability. That means the instability preexisted due to rotation and was not induced by lacing wires.
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Huang, Zhiqiang, Xun Peng, Gang Li und Lei Hao. „Response of a Two-Degree-of-Freedom Vibration System with Rough Contact Interfaces“. Shock and Vibration 2019 (14.02.2019): 1–13. http://dx.doi.org/10.1155/2019/1691582.
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This paper is focused on the influence of the rough contact interfaces on the dynamics of a coupled mechanical system. For this purpose, a two-degree-of-freedom model of a coupled seismic-vibrator-rough-ground system is proposed with which the nonlinear vibration properties are analyzed. In this model, the force-deflection characteristic of the contact interfaces is determined by finite element analysis. By analyzing the undamped free vibration, it was found that the variation of the second-order natural frequency with amplitude increases with rougher contact interfaces; however, the amplitude has little influence on the first-order natural frequency of the system. For the harmonic excited analysis, the jump frequencies and hysteretic region both decrease with rougher contact interfaces. Moreover, it is inferred from the bifurcation diagrams that, increasing the excitation force, the system can bring about chaotic motions on rough contact interfaces.
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Fakhraei, J., H. M. Khanlo, M. Ghayour und Kh Faramarzi. „The Influence of Road Bumps Characteristics on the Chaotic Vibration of a Nonlinear Full-Vehicle Model with Driver“. International Journal of Bifurcation and Chaos 26, Nr. 09 (August 2016): 1650151. http://dx.doi.org/10.1142/s0218127416501510.
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In this paper, the chaotic behavior of a ground vehicle system with driver subjected to road disturbances is studied and the relationship between the nonlinear vibration of the vehicle and ride comfort is evaluated. The vehicle system is modeled as fully nonlinear with seven degrees of freedom and an additional degree of freedom for driver (8-DOF). The excitation force is the road irregularities that are assumed as road speed control bumps. The sinusoidal, consecutive half-sine and dented-rectangular waveforms are considered to simulate the road speed control bumps. The nonlinearities of the system are due to the nonlinear springs and dampers that are used in the suspension system and tires. The governing differential equations are extracted under Newton–Euler laws and solved via numerical methods. The chaotic behaviors were studied in more detail with special techniques such as bifurcation diagrams, phase plane portrait, Poincaré map and Lyapunov exponents. The ride comfort was evaluated as the RMS value of the vertical displacement of the vehicle body and driver. Firstly, the effect of amplitude (height) and frequency (vehicle’s speed) of these speed control bumps on chaotic vibrations of vehicle are studied. The obtained results show that various forms of vibrations, such as periodic, subharmonic and chaotic vibrations, can be detected in the system behavior with the change of the height and frequency of speed control bumps and present different types of strange attractors in the vehicle with and without driver. Then, the influence of nonlinear vibration on ride comfort and the relationship between chaotic vibrations of the vehicle and driving comfort are investigated. The results of analyzing the RMS diagrams reveal that the chaotic behaviors can directly affect the driving comfort and lead to the driver’s comfort being reduced. The obtained results can be used in the design of vehicle and road bumps pavement.
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Crisci, Giovanni, Giancarlo Ramaglia, Gian Piero Lignola, Francesco Fabbrocino und Andrea Prota. „Effects of the Mortar Matrix on the Flexural Capacity of Masonry Cross Sections Strengthened with FRCM Materials“. Applied Sciences 10, Nr. 21 (08.11.2020): 7908. http://dx.doi.org/10.3390/app10217908.
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The strengthening intervention strategies that exist for masonry buildings are based on the use of thin composites and are a recent activity used in structural engineering. Nowadays, mortar matrices are frequently found instead of epoxy resins, since the fiber reinforced cementitious matrix (FRCM) composites are more compatible with masonry than fiber reinforced plastic (FRP) ones. The mortar matrix in FRCM composites is not comparable to the epoxy resin, and therefore its contribution is different not only in traction but above all on the compression side. Due to its larger thickness, if compared to the epoxy resin, the impact of the mortar matrix on the flexural response of strengthened cross sections is not negligible. This paper aimed to investigate the influence of the contribution of the mortar matrix on the compression side on the flexural capacity of strengthened cross section. As such, p–m interaction domains and bending moment–curvature diagrams were evaluated to understand the influence of several mechanical properties of fiber and mortar matrices on FRCM efficiency, typical of real applications. Hence, the impact of several constitutive relationships of composites (linear and bilinear behavior) was considered for the structural analysis of the strengthened cross section. The presented results are all completely in a dimensionless form; therefore, independent of geometry and mechanical parameters can be the basis for developing standardized design and/or verification methodologies useful for the strengthening systems for masonry elements.