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Статті в журналах з теми "Unbalanced mode"
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Tang, Zhong, Xiyao Li, Xin Liu, Hui Ren, and Biao Zhang. "Dynamic Balance Method for Grading the Chain Drive Double Threshing Drum of a Combine Harvester." Applied Sciences 10, no. 3 (February 4, 2020): 1026. http://dx.doi.org/10.3390/app10031026.
Повний текст джерелаАнотація:
Although the individual threshing drum of a combine harvester was balanced on a dynamic balancing machine before it is assembled, there were still unbalances after multiple drums were assembled with the chain drive. In this paper, the double drums with a chain drive of a crawler combined harvester were selected as the research subject. The aim of this study was to develop a dynamic unbalance mode for grading chain drive double drums. Based on the dynamic unbalance characteristics of the main driven drum, the experimental research on the radial balance of the driven drum end face was carried out. It was known that the chain drive had a direct and obvious influence on the unbalanced phase of the drum. The unbalance of the drive load had an obvious effect on unbalanced amplitude of an active drum through the transfer characteristics of the chain drive. For the multi-stage transmission characteristics of a combine harvester, a step-by-step balanced grading chain drive double drum dynamic balancing method was practiced. Results showed that the unbalanced amplitude after balancing threshing drum I chain transmission mode of the combine harvester can be reduced by a maximum of 91%. Simultaneously, the unbalanced amplitude of threshing drum II can reduced by a maximum of 69.2%. The size and position of the wrap angle of the chain drive would directly affect the phase of the two equivalent unbalanced masses.
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Xu, Lin, Wei Yu, and Jian-Xin Chen. "Unbalanced-/Balanced-to-Unbalanced Diplexer Based on Dual-Mode Dielectric Resonator." IEEE Access 9 (2021): 53326–32. http://dx.doi.org/10.1109/access.2021.3070328.
Повний текст джерела
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Huang, Mei, Zhao Yang Xing, Yuan Yuan Zhao, Jian Nan Tang, and Hao Yuan. "Modal Analysis and Unbalanced Response Analysis of Rotor System." Applied Mechanics and Materials 668-669 (October 2014): 209–12. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.209.
Повний текст джерелаАнотація:
In this article, the entity model of the bearing-rotor system is established and meshed in ANSYS. The natural frequency and vibration mode of the rotor system is analyzed in order to avoid the occurrence of resonance. At the same time, the results showed that not only the location of the unbalance incentive of the system should be taken into account, but also consider the size of the unbalanced force.
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Xia, Mingchao, and Yanhui Mao. "Integral Sliding Mode Control Strategy of D-STATCOM for Unbalanced Load Compensation under Various Disturbances." Mathematical Problems in Engineering 2013 (2013): 1–14. http://dx.doi.org/10.1155/2013/932389.
Повний текст джерелаАнотація:
Control strategies of D-STATCOM for unbalanced load compensation under internal and external disturbances were discussed. Linear control strategies do not have a satisfactory dynamic performance and become invalid under internal or external disturbances. To guarantee a good precision and robustness, a control strategy combining input-output feedback linearization technique with integral sliding mode control (ISMC) method was applied to D-STATCOM for unbalanced load compensation. The strategy has features of simple structure and is easy to implement. A 10 MVar/10 kV D-STATCOM simulation system was built in PSCAD/EMTDC to verify the effectiveness and robustness of the control strategy proposed. Simulation results show that the control strategy can compensate reactive power and eliminate unbalance simultaneously under various disturbances.
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Li, Yu, Zhong Tang, Xinzhong Wang, Hao Zhang, and Yaoming Li. "Bearing Seat Vibration Modes Undergoing Unbalanced Excitation of Multirotating Drums." Shock and Vibration 2021 (December 28, 2021): 1–20. http://dx.doi.org/10.1155/2021/5655150.
Повний текст джерелаАнотація:
Transmission modes of multiple rotating parts on combine harvester are complex and diverse, which resulted in large vibration and poor stability when the entire machine is harvesting. Aiming at the complex vibration problem of the combine harvester threshing system, this paper established the dynamic response model of the multidrum parallel system under different transmission modes and solved the vibration characteristics of the system. An experiment on the axial unbalance response of the parallel drum system under different transmission modes was carried out. The results show that the internal units of the threshing system form a whole through the transmission system, which causes the unbalanced response of the system to be superimposed on parallel threshing drums, thereby increasing the vibration amplitude. In addition, the change of the transmission mode will cause the vibration transmission path in the system to change greatly, and the boundary conditions of the system will be changed at the same time, which will eventually lead to the change of the unbalanced response characteristics.
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Naumov, IgorV, and Sergey V. Podyachikh. "The 0.38 kV “Green Network” Operating Modes Simulation with Multi-Level Unbalanced Power Consumption." IOP Conference Series: Earth and Environmental Science 990, no. 1 (February 1, 2022): 012055. http://dx.doi.org/10.1088/1755-1315/990/1/012055.
Повний текст джерелаАнотація:
Abstract The article considers modeling, parameters calculation and analysis of the rural electric networks operating modes, containing power take-off units with multi-level unbalanced power consumption. At the same time, a low-voltage electrical network section fragment is considered as a certain cluster in the structure of an extensive and heterogeneous 0.38 kV network. The model is made for a certain “green network” cluster variant, containing several nodes of highly unbalancing power consumption with a balancing device (BD). Connecting options the BD in various power take-off nodes, including power supply buses, are considered. As a balancing technical means, a device is presented that has a minimum resistance to zero-sequence currents with its power automatically control in a zero-sequence currents function. The main criteria for assessing the currents and voltages unbalanced level are the zero-sequence voltage unbalance coefficient, which characterizes the power quality, as well as the power loss coefficient, which characterizes the increase in power and energy losses in the unbalanced mode. Based on the developed method, algorithm and computer program “Unbalance”, the calculation was made and the changes characteristics in the studied indicators were constructed using modern the Matlab graphics editor technologies. The analysis of the studied indicators was carried out, on the which basis the most appropriate node in the electrical network model was determined, where the functioning efficiency of the balancing device will be the greatest.
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Agili, Sedig S., Stephen B. Smith, and Vittal Balasubramanian. "Unbalanced line characterization for differential-mode operation." Microwave and Optical Technology Letters 48, no. 6 (2006): 1169–74. http://dx.doi.org/10.1002/mop.21549.
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Li, Feng Lin, Shu Ju Hu, and Ling Ling Wang. "Control of Quasi-Z Source Inverter with Super Capacitor under Unbalanced Grid Fault Conditions." Applied Mechanics and Materials 291-294 (February 2013): 2124–31. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.2124.
Повний текст джерелаАнотація:
The quasi-Z-source inverter (qZSI) has some unique advantages and is suitable for renewable energy sources such as solar and wind generation system. In order to make the inverter have the ride-through ability and the current into the grid symmetrical when unbalanced grid faults occur, the topology of qZSI with super capacitor substituting the low voltage capacitor and the unbalance control strategy were proposed. With a super capacitor the system can balance and smooth the power between the generation unit and grid, also the current injected into the grid can be symmetrical through the unbalance control method. The circuit of the new topology and the mathematical model of the three-phase converter under grid voltage unbalance conditions have been analyzed. And then, closed-loop control scheme for the proposed system is used to control the power flow of generation unit, grid and super capacitor in this system, also unbalance control strategies in positive (dq) + and negative (dq) – reference frames have been implemented in the grid-connected qZSI system to make the current into the grid symmetrical during the grid fault. The operating mode during unbalanced grid fault is simulated in MATLAB/Simulink, and the simulation results are presented to verify the theoretical analysis and the control scheme.
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Wetzel, Alfredo N., Leslie M. Smith, Samuel N. Stechmann, Jonathan E. Martin, and Yeyu Zhang. "Potential Vorticity and Balanced and Unbalanced Moisture." Journal of the Atmospheric Sciences 77, no. 6 (May 6, 2020): 1913–31. http://dx.doi.org/10.1175/jas-d-19-0311.1.
Повний текст джерелаАнотація:
Abstract Atmospheric flows are often decomposed into balanced (low frequency) and unbalanced (high frequency) components. For a dry atmosphere, it is known that a single mode, the potential vorticity (PV), is enough to describe the balanced flow and determine its evolution. For a moist atmosphere with phase changes, on the other hand, balanced–unbalanced decompositions involve additional complexity. In this paper, we illustrate that additional balanced modes, beyond PV, arise from the moisture. To support and motivate the discussion, we consider balanced–unbalanced decompositions arising from a simplified Boussinesq numerical simulation and a hemispheric-sized channel simulation using the Weather Research and Forecasting (WRF) Model. One important role of the balanced moist modes is in the inversion principle that is used to recover the moist balanced flow: rather than traditional PV inversion that involves only the PV variable, it is PV-and-M inversion that is needed, involving M variables that describe the moist balanced modes. In examples of PV-and-M inversion, we show that one can decompose all significant atmospheric variables, including total water or water vapor, into balanced (vortical mode) and unbalanced (inertio-gravity wave) components. The moist inversion, thus, extends the traditional dry PV inversion to allow for moisture and phase changes. In addition, we illustrate that the moist balanced modes are essentially conserved quantities of the flow, and they act qualitatively as additional PV-like modes of the system that track balanced moisture.
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Xue, Quan, Jin Shi, and Jian-Xin Chen. "Unbalanced-to-Balanced and Balanced-to-Unbalanced Diplexer With High Selectivity and Common-Mode Suppression." IEEE Transactions on Microwave Theory and Techniques 59, no. 11 (November 2011): 2848–55. http://dx.doi.org/10.1109/tmtt.2011.2165960.
Повний текст джерелаДисертації з теми "Unbalanced mode"
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Hartono, Aryudha. "Microgrid Safety and Protection Strategies." Thesis, KTH, Elektroteknisk teori och konstruktion, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226593.
Повний текст джерелаАнотація:
One of the challenging issues with the Microgrid is that the bidirectional power flow providedby the distributed generator (DG) which modify the fault current level. Furthermore, theinverter based-renewable energy source (IB-RES) limits the total fault current contributionto the grid due to its thermal capability. Since Microgrid should be able to operate in gridconnectedand islanded mode, protection strategies are needed to solve this challenging issue.By only having IB-RES and battery storage system, the fault condition and normaloperation cannot be distinguished. Apart from fault clearing issue, there is a consideration tostudy the fault isolation in the Microgrid under the limited fault current provided by IB-RES.To have fault isolation capability, the intelligent electrical device (IED) is needed. The firststep is to find a method that can detect a fault under the fault level modification constraint.This thesis presents a zero and negative sequence current protection to detect a fault.However, to make it selective, this protection will be applied directionally. It is common thatthe distribution grid has unbalanced load operation, thus providing zero and negativesequence component in the grid. To apply the directional zero and negative sequence currentprotection, the unbalanced load flow is simulated to distinguish the fault and normaloperation under unbalanced load condition.Safety and regulation are discussed briefly in this thesis. It is important that each of theIB-RES has fault ride-through (FRT) capability that follows a regulation. However, thisregulation is expected to have a coordination with the proposed protection in the Microgridso the reliability, selectivity, and sensitivity can be achieved in grid-connected and islandedmode. This thesis shows the coordination between fuses, IED, and inverter FRT capability.After providing a protection strategy, the adaptability of the proposed protection isassessed regarding of Microgrid expansion. The result shows that by applying the schemeand following the grading margin requirement that is presented in this thesis, the Microgridexpansion will not disrupt the proposed protection coordination. Since it is known that thedistribution grid is expanding its load capacity and microgeneration in continuous basis, it isconvenient that the proposed protection in the IED is expected to be adaptable, means that ithas a fixed IED setting when the grid is expanded. The analysis is performed by electrical transient analysis program (ETAP) and MatlabSimulink. The short circuit analysis, sequence-of-operation, and unbalanced load flow aresimulated by ETAP, while the protection stability is simulated by Matlab Simulink.Ett problem som finns med microgrid är att de distribuerade produktionsgeneratorerna harett dubbelriktat effektflöde som modifierar felströmmen. Dessutom, inverterbaseradeförnyelsebara energikällor (IB-RES) begränsar det totala felströmsbidraget på grund av desstermiska kapacitet. Eftersom microgrids ska vara operativ vid både anslutning till externt nätsamt önätsdrift behövs skyddsstrategier för att kunna hantera fel, speciellt vid önätsdrift.Om endast IB-RES och batterilager används kan feldrift och normal drift inte särskiljas.Bortsätt från felhantering är det viktigt att studera felbortkoppling för microgrid underbegränsad felström som fås av IB-RES. För att kunna åstadkomma felbortkoppling behöveren IED (från engelskans Intelligent Electronic Device). Det första steget är att finna en metodför att kunna detektera fel under fel nivå modifiering. Denna avhandling tittar på att användanoll- och minusföljds ström sekvensskydd för att detektera fel. För att göra skyddet selektivtkommer det att titta på riktningen av effektflödet. I distributionsnät är det vanligt att haobalanserade laster vilket medför noll- och negativa sekvenskomponenter i nätet. För atttillämpa riktningsskydd för noll och negativ sekvens ström simuleras ett obalanserateffektflöde för att särskilja på feldrift och normal drift vid obalanserad last.Säkerhet och förordningar diskuteras kortfattat i denna avhandling. Det är viktigt att varjeIB-RES har en feltålighet som följer vissa förordningar. Denna förordning förväntassamordna det föreslagna skyddet i micronåt så att pålitlighet, selektivitet och känslighet kanåstadkommas vid nätanslutning och önätsdrift. Denna avhandling visar samordningen mellansäkringar, IED och feltåligheten för växelomriktare.Anpassningsförmågan för det föreslagna skyddet bedöms med avseende på expansion avmicrogrid. Resultatet visar att en expansion av ett microgrid inte kommer att störa denföreslagna samordningen om skyddsmetoden och tidsfördröjningskravet som presenteras idenna avhandling följs. Eftersom det är känt att distributionsnätet kommer att fortsätta ökasin lastkapacitet och mikrogenerering, är det lämpligt att skyddet förväntas varaanpassningsbart vilket innebär att det har en fast IED inställning när nätet expanderas.Analysen genomförs med mjukvarorna electrical transient analysis program (ETAP) ochMatlab Simulink. Kortslutningsanalysen, arbetssekvensen och obalanserad lastflödesimuleras av ETAP, medan skyddsstabiliteten simuleras av Matlab Simulink.
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Kazem, Hussein A. "Development and analysis of supply side rectifier circuits model under balanced & unbalanced supply conditions." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506526.
Повний текст джерела
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Сиротин, Юрий Александрович. "Компенсация и учет реактивной мощности в электротехнических системах с несимметричными режимами". Thesis, НТУ "ХПИ", 2014. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21116.
Повний текст джерелаАнотація:
Диссертация на соискание ученой степени доктора технических наук по специальности 05.09.03 - электротехнические комплексы и системы. - Национальный технический университет "Харьковский политехнический институт". - Харьков, 2015.
Диссертационная работа посвящена решению важной научно-технической проблемы создания обобщенной теории мощности (ТМ), единого комплексного подхода к компенсации и учету неактивных составляющих полной мощности (ПМ) для обеспечения оптимального режима потребления электрической энергии (ЭЭ) в точке подключения неидеальной нагрузки к сети с несимметричным напряжением. На основе теоретических исследований, использующих метод ортогонального разложения векторов мгновенных значений 3-фазного тока и напряжения, получена обобщенная векторная математическая модель (ВММ), которая классифицирует электроэнергетические режимы (ЭР) в 3-фазной схеме электроснабжения с помощью векторной мгновенной мощности (ММ). Сформулированы и обоснованы предложения политики повышения качества поставки и потребления электроэнергии в 3-фазной сети, сочетающие установку поставщиком в каждой точке подключения потребителя счетчика, измеряющего каждую ЭКТ, заключение публичного договора, в котором предусмотрена оплата каждой ЭКТ по своему тарифу, установки потребителем КУ, применение компенсации неактивных составляющих ПМ на каждом уровне для уменьшения групповых потерь в сетях поставщика. Предложенная политика позволит учесть разную степень влияния ЭКТ на качество электроэнергии и обеспечит потребителю выбор выгодного для него способа потребления электроэнергии, стимулирует установку КУ, а поставщику обеспечит надежную методологию повышения качества электроэнергии в рамках несимметрии нагрузки и напряжения.Thesis for a Doctor’s degree in Engineering Sciences by specialty 05.09.03 - Electrical Engineering Complexes and Systems. - National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2015. The dissertation is devoted an important scientific and technical issues to improve the power quality of supply and consumption (SC) in three-phase networks through further development of die power theory, development of methods and ways of compensation, proposals for the accounting and payment of the inactive components of the apparent power (AP). A generalized mathematical model (GMM) of electric power processes (EPP) in a 3-phase SC scheme was developed. The model of 3-wire circuit is provided by a special (О-balanced) mode of the model 4-wire circuit The developed GMM classifies the SC modes using the vectorial instantaneous power (IP) and summarizes the class of models used in the theory of IP. For sinusoidal mode with asymmetric voltage the refines vectorial mathematical model (VMV) 3-phasors (complex rms vectors) was created. The analytical expressions for the integral characteristics of the classified modes are founded and their relationship with standard IP and vectorial IP are established. With asymmetrical voltage and asymmetrical loading a sinusoidal mode can be both unbalanced and pulsed. Each mode is represented by its power equation and the equivalent orthogonal decomposition of the 3-phase current Both decompositions are used to create the optimal mode of SC with a constant IP at asymmetrical voltage. The proposed compensator provides the non-puised energy supply with the highest possible power factor and with the same average (active) power as the initial current. Based on the evaluation and calculation of the power equation components of a unbalanced mode was developed a methodology for calculating the loss of the measuring selection. A methodology and technique of analytical calculation of additional losses on the passport data of the connected electrical equipment was proposed. Formulated and proved offers on differential measurement and payment of the energy components of AP will stimulate consumer sets the compensator, and provide a reliable methodology for improving the quality of SC (within unbalance loading and voltage).
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Phan, Anh Tuan. "Power Systems Model Developments for Power Qality Monitoring : Application to Fundamental Frequency and Unbalance Estimation." Thesis, Mulhouse, 2016. http://www.theses.fr/2016MULH8692/document.
Повний текст джерелаАнотація:
Les énergies renouvelables, l’énergie sous la forme électrique et son transport à l’aide de réseaux électriques intelligents représentent aujourd’hui des enjeux majeurs car ils ont de grands impacts environnementaux et sociétaux. Ainsi, la production, le transport et la gestion de l’énergie électrique, continuent toujours à susciter un intérêt croissant. Pour atteindre ces objectifs, plusieurs verrous technologiques doivent être levés. Au-delà des questions liées aux architectures des réseaux électriques, aux modèles, aux outils de dimensionnement, à la formalisation de caractéristiques et d’indicateurs, aux contraintes et aux critères, à la gestion et à la production décentralisée, la qualité de la puissance électrique est centrale pour la fiabilité de l’ensemble du système de distribution. Les perturbations affectent la qualité des signaux électriques et peuvent provoquer des conséquences graves sur les autres équipements connectés au réseau. Les travaux de cette thèse s’inscrivent dans ce contexte et de fait ils sont orientés vers le développement de modèles, d’indicateurs et de méthodes de traitement des signaux dédiés à la surveillance en temps-réel des performances des réseaux de distribution électrique.Cette thèse analyse la qualité de la puissance électrique, en prenant en compte plusieurs caractéristiques bien connues ainsi que leur pertinence. Les modèles des systèmes électriques et les méthodes de traitement du signal pour estimer leurs paramètres sont étudiés pour des applications en temps-réel de surveillance, de diagnostic et de contrôle sous diverses conditions. Parmi tous, la fréquence fondamentale est l’un des paramètres les plus importants pour caractériser un système de distribution électrique. En effet, sa valeur qui est censée être une constante, varie en permanence et reflète la dynamique de l’énergie électrique disponible. La fréquence peut également être affectée par certaines productions d’énergie renouvelable et peut être influencée par des mauvaises synchronisations de certains équipements. En outre, la puissance absorbée par les charges ou produite par des sources est généralement différente d’une phase à l’autre. Évidemment, la plupart des installations électriques existantes avec plusieurs phases, qu’elles soient résidentielles ou industrielles, travaillent dans des conditions déséquilibrées. Identifier les composantes symétriques de tension est dans ce cas un moyen pertinent pour quantifier le déséquilibre entre les phases d’un système électrique.De nouvelles représentations de type espace d’état et modélisant des systèmes électriques sont proposées pour estimer la fréquence fondamentale et pour identifier les composantes symétriques de tension des systèmes électriques triphasés et déséquilibrés. Le premier modèle d’espace d’état proposé considère la fréquence fondamentale comme connue ou obtenue par un autre estimateur. En contrepartie, il fournit les autres paramètres caractérisant le système électrique. Un second modèle d’état-espace est introduit. Il est original dans le sens où il ne nécessite aucune connaissance de la fréquence fondamentale. Une de ses variables d’état est directement reliée à la fréquence et permet donc de la déduire. En outre, ce nouvel espace d’état est parfaitement capable de représenter des systèmes électriques à trois phases équilibrés et non équilibrés. [...]Renewable energy, electricity and smart grids are core subjects as they have great environmental and societal impacts. Thus, generating, transporting and managing electric energy, i.e., power, still continue to drive a growing interest. In order to properly achieve these goals, several locks must be removed. Beyond issues related to the distribution architecture, the formalization of models, sizing tools, features and indicators, constraints and criteria, decentralized generation and energy management, power quality is central for the whole grid’s reliability. Disturbances affect the power quality and can cause serious impact on other equipment connected to the grid. The work of this thesis is part of this context and focuses on the development of models, indicators, and signal processing methods for power quality monitoring in time-varying power distribution systems.This thesis analyzes the power quality including several well-known features and their relevance. Power system models and signal processing methods for estimating their parameters are investigated for the purpose of real-time monitoring, diagnostic and control tasks under various operating conditions. Among all, the fundamental frequency is one of the most important parameters of a power distribution system. Indeed, its value which is supposed to be a constant varies continuously and reflects the dynamic availability of electric power. The fundamental frequency can also be affected by renewable energy generation and by nasty synchronization of some devices. Moreover, the power absorbed by loads or produced by sources is generally different from one phase to the other one. Obviously, most of the existing residential and industrial electrical installations with several phases work under unbalanced conditions. Identifying the symmetrical components is therefore an efficient way to quantify the imbalance between the phases of a grid. New state-space representations of power systems are proposed for estimating the fundamental frequency and for identifying the voltage symmetrical components of unbalanced three-phase power systems. A first state-space representation is developed by supposing the fundamental frequency to be known or to be calculated by another estimator. In return, it provides other parameters and characteristics from the power system. Another original state-space model is introduced which does not require the fundamental frequency. Here, one state variable is a function of the frequency which can thus be deduced. Furthermore this new state-space model is perfectly are able to represent a three-phase power system in both balanced and unbalanced conditions. This not the case of lots of existing models. The advantage of the proposed state-space representation is that it gives directly access to physical parameters of the system, like the frequency and the amplitude and phase values of the voltage symmetrical components. Power systems parameters can thus be estimated in real-time by using the new state-space with an online estimation process like an Extended Kalman Filter (EKF). The digital implementation of the proposed methods presents small computational requirement, elegant recursive properties, and optimal estimations with Gaussian error statistics.The methods have been implemented and validated through various tests respecting real technical constraints and operating conditions. The methods can be integrated in active power filtering schemes or load-frequency control strategies to monitor power systems and to compensate for electrical disturbances
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Shan, Liang. "Joint Gaussian Graphical Model for multi-class and multi-level data." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/81412.
Повний текст джерелаАнотація:
Gaussian graphical model has been a popular tool to investigate conditional dependency between random variables by estimating sparse precision matrices. The estimated precision matrices could be mapped into networks for visualization. For related but different classes, jointly estimating networks by taking advantage of common structure across classes can help us better estimate conditional dependencies among variables. Furthermore, there may exist multilevel structure among variables; some variables are considered as higher level variables and others are nested in these higher level variables, which are called lower level variables. In this dissertation, we made several contributions to the area of joint estimation of Gaussian graphical models across heterogeneous classes: the first is to propose a joint estimation method for estimating Gaussian graphical models across unbalanced multi-classes, whereas the second considers multilevel variable information during the joint estimation procedure and simultaneously estimates higher level network and lower level network.
For the first project, we consider the problem of jointly estimating Gaussian graphical models across unbalanced multi-class. Most existing methods require equal or similar sample size among classes. However, many real applications do not have similar sample sizes. Hence, in this dissertation, we propose the joint adaptive graphical lasso, a weighted L1 penalized approach, for unbalanced multi-class problems. Our joint adaptive graphical lasso approach combines information across classes so that their common characteristics can be shared during the estimation process. We also introduce regularization into the adaptive term so that the unbalancedness of data is taken into account. Simulation studies show that our approach performs better than existing methods in terms of false positive rate, accuracy, Mathews correlation coefficient, and false discovery rate. We demonstrate the advantage of our approach using liver cancer data set.
For the second one, we propose a method to jointly estimate the multilevel Gaussian graphical models across multiple classes. Currently, methods are still limited to investigate a single level conditional dependency structure when there exists the multilevel structure among variables. Due to the fact that higher level variables may work together to accomplish certain tasks, simultaneously exploring conditional dependency structures among higher level variables and among lower level variables are of our main interest. Given multilevel data from heterogeneous classes, our method assures that common structures in terms of the multilevel conditional dependency are shared during the estimation procedure, yet unique structures for each class are retained as well. Our proposed approach is achieved by first introducing a higher level variable factor within a class, and then common factors across classes. The performance of our approach is evaluated on several simulated networks. We also demonstrate the advantage of our approach using breast cancer patient data.Ph. D.
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Pham, Hai Minh. "Computation of the vibration of a whole aero-engine model with nonlinear bearings." Thesis, University of Manchester, 2010. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:128171.
Повний текст джерелаАнотація:
Aero-engine assemblies are complex structures typically involving two or three nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The deployment of SFDs into such structures is highly cost-effective but requires careful calculation since they can be highly nonlinear in their performance, particularly if they are unsupported (i.e. without a retainer spring). The direct study of whole-engine models with nonlinear bearings has been severely limited by the fact that current nonlinear computational techniques are not well-suited for complex large-order systems. The main contributions of this thesis are: • A procedure for unbalance response computation, suitable for generic whole-engine models with nonlinear bearings, which significantly extends the capability of current finite element packages. This comprises two novel nonlinear computational techniques: an implicit time domain integator referred to as the Impulsive Receptance Method (IRM) that enables rapid computation in the time domain; a whole-engine Receptance Harmonic Balance Method (RHBM) for rapid calculation of the periodic response in the frequency domain. Both methods use modal data calculated from a one-off analysis of the linear part of the engine at zero speed.• First-ever analyses on real twin-spool and three-spool engines. These studies illustrate the practical use of these solvers, provide an insight into the nonlinear dynamics of whole-engines and correlate with a limited amount of industrial experimental data. Both IRM and RHBM are directly formulated in terms of the relative response at the terminals of the nonlinear bearings. This makes them practically immune to the number of modes that need to be included, which runs into several hundreds for a typical engine. The two solvers are extensively tested on two/three-shaft engine models (with 5-6 SFDs) provided by a leading engine manufacturer using an SFD model that is used in industry. The tests show the IRM to be many times faster than an established robust conventional implicit integrator while achieving a similar level of accuracy. It is also shown to be more reliable than another popular implicit algorithm. The RHBM enables, for the first time, the frequency domain computation of the nonlinear response of whole-engine models. Its use is illustrated for both Single-Frequency Unbalance (SFU) excitation (unbalance confined to only one shaft) and Multi-Frequency Unbalance (MFU) excitation (unbalance located on two or more shafts, rotating at different speeds). Excellent correlation is demonstrated between RHBM and IRM.The parametric studies compare and contrast the frequency spectra for SFU and MFU cases. They also reveal the varying degree of lift at the unsupported SFDs. The sensitivity of the response to end-sealing and bearing housing alignment is also illustrated. It is demonstrated that the use of suitably preloaded vertically oriented “bump-springs” at the SFDs of heavy rotors produces a significant improvement in journal lift. It is also shown that the consideration of a slight amount of distributed damping in the structure significantly affects the predicted casing vibration levels, bringing them closer to measured levels, while having little effect on the SFD orbits.
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Wang, Shuo. "Characterization and Cancellation of High-Frequency Parasitics for EMI Filters and Noise Separators in Power Electronics Applications." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27885.
Повний текст джерелаАнотація:
Five chapters of this dissertation concentrate on the characterization and cancellation of high frequency parasitic parameters in EMI filters. One chapter addresses the interaction between the power interconnects and the parasitic parameters in EMI filters. The last chapter addresses the characterization, evaluation and design of noise separators. Both theoretical and experimental analyses are applied to each topic.
This dissertation tries to explore several important issues related to EMI filters and noise separators. The author wishes to find some helpful approaches to benefit the understanding and design of EMI filters. The contributions of the dissertation can be summarized below:
1) Identification of mutual couplings and their effects on EMI filter performance
2) Extraction of mutual couplings using scattering parameters
3) Cancellation of mutual couplings to improve EMI filter performance
4) Cancellation of equivalent series inductance to improve capacitor performance
5) Analysis of mode transformations due to the imperfectly balanced parameters in EMI filters
6) Analysis of interaction between power interconnects and EMI filters on filter high-frequency performance
7) Modeling and design of high-performance noise separator for EMI diagnosis
8) Identification of the effects of parasitics in boost PFC inductor on DM noise
Although all topics are supported by both theory and experiments, there may still be some mistakes in the dissertation. The author welcomes any advice and comments. Please send them via email to shuowang@ieee.org. ThanksPh. D.
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Junior, Edson Luis Geraldi. "Parameter estimation for a three-phase distributed synchronous generator model using noisy measurements." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-19102018-143704/.
Повний текст джерелаАнотація:
The simplified models of synchronous generators, widely used in stability studies of large electric power systems, are not completely suitable for the stability analysis and the design of controllers of distributed synchronous generators, generally connected to typically unbalanced branches. To more accurately analyze the systems with distributed generation, it is necessary to utilize synchronous generator models that consider frequency variation in their electrical equations. Furthermore, this model must represent possible unbalanced three-phase voltages at the generator terminals as well. Nonetheless, to provide reliable responses, the parameters of this more detailed model should be known. Thus, this work assesses the influence of the parameters on the responses of a detailed synchronous generator model, suitable to depict unbalanced operating conditions, and proposes an approach for the estimation of its most important parameters. In the proposed structure, we first employ Trajectory Sensitivity Functions to evaluate the dependency of the responses of this model with respect to its parameters and, from that, we rank them according to their importance. Subsequently, we apply an estimation process that utilizes the Unscented Kalman Filter with the aid of a genetic algorithm to estimate the main parameters of this synchronous generator model under unbalanced operating conditions. To obtain the results and, therefore, assess the proposed estimation approach, we make use of a system which comprises a synchronous generator connected to a three-phase unbalanced load. In addition to the unbalanced operation of the test system, we also consider noises due to the constant load switching, typical of distribution systems. The estimations performed for three operating conditions of the generator were very satisfactory, which demonstrates the efficiency of the proposed approach to obtain adequate models for the description of synchronous generator operation under unbalanced operating conditions.Os modelos simplificados de geradores síncronos, amplamente utilizados em estudos de estabilidade de grandes sistemas elétricos de potência, não são completamente adequados para a análise de estabilidade e projetos de controladores dos geradores síncronos distribuídos, geralmente conectados a sistemas tipicamente desequilibrados. Para que os sistemas com geração distribuída possam ser analisados mais fidedignamente, é necessária a utilização de um modelo de gerador síncrono que considere a variação de frequência em suas equações elétricas. Além disso, esse modelo também deve ser capaz de representar possíveis tensões trifásicas desequilibradas nos terminais do gerador. Entretanto, para que esse modelo mais detalhado possa fornecer respostas coerentes com a realidade, deve-se conhecer seus parâmetros. Dessa forma, este trabalho avalia a influência dos parâmetros nas respostas de um modelo de gerador síncrono mais detalhado, adequado para representar operações desbalanceadas, e propõe uma abordagem para a estimação de seus parâmetros mais importantes. Nessa estrutura, inicialmente empregam-se as Funções de Sensibilidade de Trajetória para avaliar a dependência das respostas desse modelo em relação aos seus parâmetros e, a partir disso, ordená-los conforme sua importância. Em seguida, aplica-se um processo de estimação que utiliza o Filtro de Kalman Unscented com o auxílio de um algoritmo genético para estimar os principais parâmetros desse modelo de gerador síncrono em condições de desbalanço. Para a obtenção dos resultados e consequente avaliação da abordagem de estimação proposta, utiliza-se um sistema composto por um gerador síncrono conectado a uma carga trifásica desbalanceada. Além da operação desbalanceada desse sistema teste, também são considerados ruídos devidos ao constante chaveamento de cargas, típicos de sistemas de distribuição. As estimações realizadas para três condições de operação do gerador foram bem satisfatórias, indicando a eficiência da abordagem proposta na obtenção de modelos adequados para descrever a operação de geradores síncronos em condições de desbalanço.
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Alkhatib, Rami. "Human locomotion analysis, classification and modeling of normal and pathological vertical ground reaction force signals in elderly." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES029/document.
Повний текст джерелаАнотація:
La marche est définie par des séquences de gestes cycliques et répétées. Il a été déjà montré que la vitesse et la variabilité de ces séquences peuvent révéler des aptitudes ou des défaillances motrices. L’originalité de ce travail est alors d’analyser et de caractériser les foulées de sujets âgés à partir des signaux de pression issus de semelles instrumentées lors de la marche, au moyen d’outils de traitement du signal. Une étude préliminaire, sur les signaux de pression générés lors de la marche, nous a permis de mettre en évidence le caractère cyclo-stationnaire de ces signaux. Ces paramètres sont testées sur une population de 47 sujets. Tout d'abord, nous avons commencé par un prétraitement des signaux et nous avons montré dans la première de cette thèse que le filtrage peut éliminer une partie vitale du signal. C’est pourquoi un filtre adaptatif basé sur la décomposition en mode empirique a été conçu. Les points de retournement ont été filtrés ensuite en utilisant une technique temps-fréquence appelée «synochronosqueezing». Nous avons également montré que le contenu des signaux de force de marche est fortement affecté par des paramètres inquantifiables tels que les tâches cognitives qui les rendent difficiles à normaliser. C’est pourquoi les paramètres extraits de nos signaux sont tous dérivées par une comparaison inter-sujet. Par exemple, nous avons assimilé la différence dans la répartition de poids entre les pieds. Il est également recommandé dans ce travail de choisir le centre des capteurs plutôt que de compter sur la somme des forces issues du réseau de capteurs pour la classification. Ensuite, on a montré que l’hypothèse de la marche équilibrée et déséquilibrée peut améliorer les résultats de la classification. Le potentiel de cette hypothèse est montré à l'aide de la répartition du poids ainsi que le produit de l'âge × vitesse dans le premier classificateur et la corrélation dans le second classificateur. Une simulation de la série temporelle de VGRF basé sur une version modifiée du modèle de Markov non stationnaire, du premier ordre est ensuite dérivée. Ce modèle prédit les allures chez les sujets normaux et suffisamment pour les allures des sujets de Parkinson. On a trouvé que les trois modes: temps, fréquence et espace sont très utiles pour l’analyse des signaux de force, c’est pourquoi l’analyse de facteurs parallèles est introduite comme étant une méthode de tenseur qui peut être utilisée dans le futurWalking is defined as sequences of repetitive cyclic gestures. It was already shown that the speed and the variability of these sequences can reveal abilities or motorskill failures. The originality of this work is to analyze and characterize the steps of elderly persons by using pressure signals. In a preliminary study, we showed that pressure signals are characterized by cyclostationarity. In this study, we intend to exploit the nonstationarity of the signals in a search for new indicators that can help in gait signal classification between normal and Parkinson subjects in the elderly population. These parameters are tested on a population of 47 subjects. First, we started with preprocessing the vertical ground reaction force (VGRF) signals and showed in this first part of the thesis that filtering can remove a vital part of the signal. That is why an adaptive filter based on empirical mode decomposition (EMD) was built. Turning points are filtered using synochronosqueezing of time-frequency representations of the signal. We also showed that the content of gait force signals is highly affected by unquantifiable parameter such as cognitive tasks which make them hard to be normalized. That is why features being extracted are derived from inter-subject comparison. For example we equated the difference in the load distribution between feet. It is also recommended in this work to choose the mid-sensor rather than relying on summation of forces from array of sensors for classification purposes. A hypothesis of balanced and unbalanced gait is verified to be potential in improving the classification accuracy. The power of this hypothesis is shown by using the load distribution and Age×Speed in the first classifier and the correlation in the second classifier. A time series simulation of VGRF based on a modified version of nonstationary- Markov model of first order is derived. This model successfully predict gaits in normal subjects and fairly did in Parkinson’s gait. We found out that the three modes: time, frequency and space are helpful in analyzing force signals that is why parallel factor analysis is introduced as a tensor method to be used in a future work
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Gao, Zhi. "Sensorless Stator Winding Temperature Estimation for Induction Machines." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/13966.
Повний текст джерелаАнотація:
The organic materials used for stator winding insulation are subject to deterioration from thermal, electrical, and mechanical stresses. Stator winding insulation breakdown due to excessive thermal stress is one of the major causes of electric machine failures; therefore, prevention of such a failure is crucial for increasing machine reliability and minimizing financial loss due to motor failure.
This work focuses on the development of an efficient and reliable stator winding temperature estimation scheme for small to medium size mains-fed induction machines. The motivation for the stator winding temperature estimation is to develop a sensorless temperature monitoring scheme and provide an accurate temperature estimate that is capable of responding to the changes in the motors cooling capability. A discussion on the two major types of temperature estimation techniques, thermal model-based and parameter-based temperature techniques, reveals that neither method can protect motors without sacrificing the estimation accuracy or motor performance.
Based on the evaluation of the advantages and disadvantages of these two types of temperature estimation techniques, a new online stator winding temperature estimation scheme for small to medium size mains-fed induction machines is proposed in this work. The new stator winding temperature estimation scheme is based on a hybrid thermal model. By correlating the rotor temperature with the stator temperature, the hybrid thermal model unifies the thermal model-based and the parameter-based temperature estimation techniques. Experimental results validate the proposed scheme for stator winding temperature monitoring. The entire algorithm is fast, efficient and reliable, making it suitable for implementation in real time stator winding temperature monitoring.
Книги з теми "Unbalanced mode"
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Du, Qingyuan. A sexually unbalanced model of current account imbalances. Cambridge, MA: National Bureau of Economic Research, 2010.
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Huang, Yukon. China’s Unbalanced Growth. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190630034.003.0004.
Повний текст джерелаАнотація:
Most observers have criticized China’s growth model as internally unbalanced, defined by its exceptionally low share of consumption to GDP and commensurately high share of investment in GDP, and externally unbalanced in generating huge trade surpluses mirrored by large trade deficits in the United States and Europe. Many theories have been advanced to explain China’s “twin” imbalances. They focus on distorted prices and excessive savings, but none have highlighted the critical role of urbanization and labor migration. China’s internal imbalances can be seen as the byproduct of a generally successful urbanization-cum-industrialization process rather than a risk. If the diagnosis is wrong, then the resulting policy prescriptions also warrant questioning. With appropriate structural reforms to increase productivity and a more efficient urbanization process, rebalancing will eventually occur without the need to artificially prop up personal consumption.
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Huang, Yukon. Origins of China’s Growth Model. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190630034.003.0003.
Повний текст джерелаАнотація:
Deng Xiaoping’s most celebrated achievement was to reshape economic incentives and concentrate development along China’s coast. In doing so, he set the stage for what is referred to as China’s unbalanced growth process. Premier Zhu Rongji kept the growth momentum going by overhauling key financial and economic institutions in response to the Asian Financial Crisis. These reforms led to unprecedented double-digit GDP growth over the three decades prior to 2010. Both Deng Xiaoping and Zhu Rongji were “policy entrepreneurs.” Through their ideas and actions, they were able to overcome vested interests, all while taking risks and launching new reform initiatives. Progress on the reform agenda slowed in the years leading up to the Global Financial Crisis as the subsequent leadership was lulled into a false sense of confidence because of China’s strong economic performance.
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McKinlay Gardner, R. J., and David J. Amor. Reproductive Failure. Edited by R. J. McKinlay Gardner and David J. Amor. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199329007.003.0019.
Повний текст джерелаАнотація:
Human conception and pregnancy is both a vulnerable and a robust process. It is vulnerable in that a large proportion of all conceptions are chromosomally abnormal, with the great majority of such pregnancies aborting. It is robust in that more than 99% of the time, a term pregnancy results in a chromosomally normal baby; unbalanced chromosomal abnormalities are seen in less than 1% of newborns. This chapter considers the somewhat surprising vulnerability of the human species to chromosome abnormality, from prior to, at, and following conception. A remarkable fraction of pregnancy loss is due to chromosomal imbalance, and there is an associated maternal age effect. This chapter considers the chromosomal contribution to miscarriage, fetal death in utero, and perinatal death. Recurrent pregnancy loss may have a chromosomal basis, and male and female infertility may relate to abnormality of, in particular, the sex chromosomes. The genetics of hydatidiform mole is reviewed.
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McKinlay Gardner, R. J., and David J. Amor. Complex Chromosomal Rearrangements. Edited by R. J. McKinlay Gardner and David J. Amor. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199329007.003.0010.
Повний текст джерелаАнотація:
Complex chromosome rearrangements (CCRs) include most of the rearrangements that would not be accounted for as “straightforward” classical categories. They may be translocations with three or more segments involved; or they may comprise a mix of translocation and, for example, inversion. Some can be extraordinarily complex. CCRs are classified as types I–IV, most falling into the “least complex” type I category, while types II–IV are grouped as “exceptional CCRs.” Many unbalanced CCRs have arisen de novo and imply no increased reproductive risk. The identification of the clinically normal balanced CCR carrier is less frequent, and for these people, the reproductive risks can be very high.
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Craissati, Jackie, and Rob Halsey. Intervening in the community. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198791874.003.0004.
Повний текст джерелаАнотація:
The Offender Personality Disorder (OPD) pathway strategy explicitly begins and ends with the community, and this ethos lies at the heart of the pathway approach to management. This chapter therefore focuses on the question of how best to deploy limited resources to greatest effect when facing the challenge of high levels of morbidity and offending, a large geographical area, and a changing staff group. Having reviewed the rather sparse literature on relevant and effective community treatment interventions, the authors consider the relative benefits of stand-alone treatment approaches, partnership working, and indirect support, before describing the mixed model chosen by the London Pathways Partnership. The chapter concludes with a reflection on progress and challenges four years on; unbalanced by politically driven changes midway, the service nevertheless has flourished, although partnership working requires constant attention if staff are to be supported to make a real difference.
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Huang, Yukon. Cracking the China Conundrum. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190630034.001.0001.
Повний текст джерелаАнотація:
China is an abnormal economic power. No country has grown so rapidly for so long and in such an extreme manner. Media coverage has soared because China’s rise is now challenging the world’s balance of power. Yet one is as likely to read about a possible financial crisis as its emergence as the world’s largest economy. But much of the analysis is flawed, as are many of the policy prescriptions. China’s unbalanced growth, for example, is seen as a risk but in reality is a virtue. Its soaring debt levels are perceived as signaling a financial collapse but can also be interpreted as evidence of financial deepening. Its trade and foreign investment initiatives are blamed for exacerbating America’s economic decline, even though there is little connection between the two. The factors that have influenced broader concerns, such as corruption and political liberalization, are often misunderstood. And Beijing’s foreign policies in Asia need to be deciphered and dealt with differently if there is to be any hope of moderating geopolitical tensions with the United States and its regional allies. Explaining why there is such extreme variation in views and why the conventional wisdom is so often wrong is the theme of this book. Observers see China’s rise through multiple lenses. Geopolitical differences in values and mistrust is part of the explanation, but differing analytical frameworks, along with China’s size and complexity, are the major reasons. Understanding these differences is critical to forging more constructive relations between China and the rest of the world.
Частини книг з теми "Unbalanced mode"
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Abdelbaset, Adel, Yehia S. Mohamed, Abou-Hashema M. El-Sayed, and Alaa Eldin Hussein Abozeid Ahmed. "Adaptive Sliding Mode Control for Grid Synchronization of a Wind Driven DFIG Under Unbalanced Grid Voltage." In Wind Driven Doubly Fed Induction Generator, 57–80. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-70108-0_5.
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Abu-Siada, Ahmed, Mohammad A. S. Masoum, Yasser Alharbi, Farhad Shahnia, and A. M. Shiddiq Yunus. "Distribution Static Compensators and their Applications in Microgrids." In Recent Advances in Renewable Energy, 87–141. UAE: Bentham Science Publishers Ltd., 2017. http://dx.doi.org/10.2174/9781681085425117020005.
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Microgrids are clusters of distributed energy resources, energy storage systems and loads which are capable of operating in grid-connected as well as in offgrid modes. In the off-grid mode, the energy resources supply the demand while maintaining the voltage and frequency within acceptable limits whereas in the gridconnected mode, the energy resources supply the maximum or nominal power and the network voltage and frequency is maintained by the grid. This chapter first summarizes the structure and control principles of microgrids. It then briefly introduces the structures and control perspectives of distribution static compensators (DSTATCOMs). Finally, some applications of DSTATCOMs are discussed in microgrids. The introduced applications are power quality improvement due to the presence of nonlinear and unbalanced loads, voltage regulation and balancing, and interphase power circulation in the case of the presence of single-phase energy resources with unequal distribution amongst phases. Each application is illustrated by examples, realized in PSCAD/EMTDC.
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de Rambures, Dominique. "A Fast but Unbalanced Growth." In The China Development Model, 47–70. London: Palgrave Macmillan UK, 2015. http://dx.doi.org/10.1057/9781137465498_4.
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Mazzaro, D., F. Pesarin, and L. Salmaso. "Permutation Tests for Effects in Unbalanced Repeated Measures Factorial Designs." In mODa 6 — Advances in Model-Oriented Design and Analysis, 183–91. Heidelberg: Physica-Verlag HD, 2001. http://dx.doi.org/10.1007/978-3-642-57576-1_20.
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Van, Tan Luong, Le Minh Thien Huynh, Tran Thanh Trang, and Duc Chi Nguyen. "Improved Control Strategy of Three-Phase Four-Wire Inverters Using Sliding Mode Input-Ouput Feedback Linearization Under Unbalanced and Nonlinear Load Conditions." In AETA 2015: Recent Advances in Electrical Engineering and Related Sciences, 261–72. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-27247-4_23.
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Martínez, Luis, Rosa M. Rodriguez, and Francisco Herrera. "Decision Making with Unbalanced Linguistic Information." In The 2-tuple Linguistic Model, 83–112. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24714-4_5.
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Walker, Ryan, Sureshkumar Perinpanayagam, and Ian Jennions. "Simulating Unbalance for Future IVHM Applications." In Topics in Model Validation and Uncertainty Quantification, Volume 4, 141–48. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-2431-4_15.
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Kashirskaya, E. N., S. V. Antonov, and I. A. Ganichev. "The Dynamic Model of Unbalanced Grinding Wheel." In Lecture Notes in Mechanical Engineering, 477–85. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-85233-7_58.
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L’vov, Max, Bernd Lacombe, and Ulrich Ehehalt. "Residual Modal Unbalance Evaluation Method by Mode Shape Weighted Optimization." In Mechanisms and Machine Science, 93–108. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99272-3_7.
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Trybus, Mariusz. "Differential Measurements of TGS Samples – Unbalanced Bridge Concept and Model." In Lecture Notes in Electrical Engineering, 360–66. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11187-8_30.
Повний текст джерелаТези доповідей конференцій з теми "Unbalanced mode"
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Nakano, H., T. Igarashi, R. Suzuki, Y. Iitsuka, and J. Yamauchi. "Consideration on radiation from an unbalanced-mode spiral antenna." In 2008 8th International Symposium on Antennas, Propagation and EM Theory. IEEE, 2008. http://dx.doi.org/10.1109/isape.2008.4735179.
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Negri, S., X. Wu, X. Liu, F. Grassi, G. Spadacini, and S. A. Pignari. "Mode Conversion in DC-DC Converters with Unbalanced Busbars." In 2019 Joint International Symposium on Electromagnetic Compatibility, Sapporo and Asia-Pacific International Symposium on Electromagnetic Compatibility (EMC Sapporo/APEMC). IEEE, 2019. http://dx.doi.org/10.23919/emctokyo.2019.8893915.
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Lee, Chong-Won, and Jong-Seok Ham. "Mode Identification for Rotating Rigid Shaft With Flexible Disks by Mode Splits." In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/vib-8266.
Повний текст джерелаАнотація:
Abstract This paper investigates the mode splits of the bending coupled modes of a rotating shaft with multiple flexible disks, in which the disks are rigidly attached to the rigid shaft supported by bearings. The bending coupled modes, in which shaft bending modes are coupled with one nodal diameter disk modes, are classified as the balanced and unbalanced modes. The mode splits of the balanced modes are the same as those of pure disk modes since the shaft does not experience any motion. On the other hand, the mode splits between pairs of the forward and backward unbalanced modes are found to be dependent upon the disk/shaft configuration and the shaft support stiffness, as well as the rotational speed and the ratio of polar to diametrical moment of inertia.
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Badini, Ludovico, Flavia Grassi, Giordano Spadacini, and Sergio A. Pignari. "Sensitivity of mode conversion in geometrically unbalanced coupled differential lines." In 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA). IEEE, 2015. http://dx.doi.org/10.1109/iceaa.2015.7297340.
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Ma, Tianyi, and Guangyao Cheng. "A novel control method for islanding mode microgrid with unbalanced load." In 2015 5th International Conference on Electric Utility Deregulation and Restructuring and Power Technologies (DRPT). IEEE, 2015. http://dx.doi.org/10.1109/drpt.2015.7432602.
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Korovkin, N. V., Q. S. Vu, and R. A. Yazenin. "A method for minimization of unbalanced mode in three-phase power systems." In 2016 IEEE NW Russia Young Researchers in Electrical and Electronic Engineering Conference (EIConRusNW). IEEE, 2016. http://dx.doi.org/10.1109/eiconrusnw.2016.7448257.
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Shiau, T. N., C. R. Wang, D. S. Liu, W. C. Wang, and W. C. Hsu. "Dynamic Spur Geared Rotor Analysis of a Multi-Shaft Turbine With Gear Parameters." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43337.
Повний текст джерелаАнотація:
The dynamic analysis of the multi-shaft turbine rotor equipped with a spur gear pair for the various gear parameters is studied. Main components of the multi-shaft turbine rotor system include the outer shaft, the inner shaft, the impeller shaft, the oil shaft and the ball bearings. The global assumed mode method (GAMM) is applied to model the rotor motion and the system equation of motion is formulated using Lagrange’s approach. The dynamic behavior of the geared multi-shaft turbine rotor system includes the natural frequency, mode shape and unbalanced response. Numerical results show that large vibration amplitude is observed in steady state at self-excited rotating speed adjacent to the natural frequency. There is no influence of the various pressure angle, modulus, and modification coefficients on unbalance response. Contrary to above cases, the variation of the system unbalance response is dominated by the tooth types rather than the other gear parameters.
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Park, Jung Seo, I. Y. Shen, and C. P. Roger Ku. "Rocking Vibration of Rotating Disk and Spindle Systems With Asymmetric Bearings." In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/vib-21566.
Повний текст джерелаАнотація:
Abstract This paper studies how bearing asymmetry affects natural frequencies and mode shapes of a rotating disk/spindle system through a numerical simulation and a perturbation analysis. Existing literature has shown that rocking motion of a rotating disk/spindle system with symmetric bearings consists of rigid body rocking of the spindle, one-nodal-diameter modes of each disk, and deformation of spindle bearings. The rocking motion, characterized by (0,1) unbalanced modes, has repeated natural frequencies when the spindle is stationary, because the disk/spindle system is axisymmetric. For a rotating spindle, (0,1) unbalanced modes evolve into forward and backward precession with circular orbits. In this paper, the numerical simulation shows that bearing asymmetry splits a pair of repeated (0,1) unbalanced modes into two modes with distinct frequencies when the spindle is stationary. Moreover, when the rotational speed increases from zero, the (0,1) unbalanced mode with lower frequency evolves into backward precession and the (0,1) unbalanced mode with higher frequency evolves into forward precession. The precession orbits are elliptical because of the bearing asymmetry. Two perturbation schemes are developed to prove the phenomena observed in the numerical simulation. For low rotational speed, a stationary disk/spindle system with symmetric bearings serves as the unperturbed system. Both the bearing asymmetry and gyroscopic effects from rotation form the perturbation. A contraction iteration predicts the effects of bearing asymmetry on natural frequencies and mode shapes. For high rotational speed, a rotating (gyroscopic) disk/spindle system with symmetric bearings serves as the unperturbed system. The bearing asymmetry forms the perturbation. To obtain a perturbation solution, the solvability condition is first derived for the unperturbed gyroscopic system. Lindsted-Poincaré approach then predicts the effects of bearing asymmetry on natural frequencies and mode shapes of the rotating disk/spindle system.
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Penugonda, Srinath, Zhifei Xu, Yuandong Guo, Muqi Ouyang, Minho Kim, Junesang Lee, Jungrae Ha, et al. "Reduction of Mode Conversion of Differential-Mode Noise to Common-Mode Noise by Printed Circuit Board Modification for Unbalanced EMI Filter Network." In 2021 IEEE International Joint EMC/SI/PI and EMC Europe Symposium. IEEE, 2021. http://dx.doi.org/10.1109/emc/si/pi/emceurope52599.2021.9559212.
Повний текст джерела
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Yin, Yunfei, Ligang Wu, Sergio Vazquez, Qingshuang Zeng, Jianxing Liu, and Leopoldo G. Franquelo. "Adaptive Sliding Mode Observer Design for Three-Phase Grid Voltage Parameters Under Unbalanced Faults." In IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2019. http://dx.doi.org/10.1109/iecon.2019.8927174.
Повний текст джерелаЗвіти організацій з теми "Unbalanced mode"
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Du, Qingyuan, and Shang-Jin Wei. A Sexually Unbalanced Model of Current Account Imbalances. Cambridge, MA: National Bureau of Economic Research, May 2010. http://dx.doi.org/10.3386/w16000.
Повний текст джерела
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González-Gómez, Andrés, Lavan Mahadeva, Diego Arturo Rodríguez-Guzmán, and Luis Eduardo Rojas. Monetary policy forecasting in a DSGE model with data that is uncertain, unbalanced and about the future. Bogotá, Colombia: Banco de la República, April 2009. http://dx.doi.org/10.32468/be.559.
Повний текст джерела