3,093 research outputs found
Dynamic analysis and control of an active engine mount system
No full textDynamic characteristics of a prototype active engine mount (AEM), designed on the basis of a hydraulic engine mount, have been investigated and an adaptive controller for the AEM has been designed. An equivalent mass-spring-damper AEM model is proposed, and the transfer function that describes the dynamic characteristics of the AEM is deduced from mathematical analysis of the model. The damping coefficient of the model is derived by considering the non-linear flow effect in the inertia track. Experiments confirmed that the model precisely describes the dynamic characteristics of the AEM. An adaptive controller using the filtered-X LMS algorithm is designed to cancel the force transmitted through the AEM. The stability of the LMS algorithm is guaranteed by using the secondary path transfer function derived on the basis of the dynamic model of the AEM. The performance test in the laboratory shows that the AEM system is capable of significantly reducing the force transmitted through the AEM
Preconditioners for the dual-primal FETI methods on nonmatching grids: Numerical study
No full textThe FETI-DP method is a substructuring method that uses Lagrange multipliers to match the continuity condition on the subdomain boundaries. For the FETI-DP method on nonmatching grids, two different formulations are known with respect to how to employ the mortar matching condition. Keeping step with the developments of the FETI-DP methods, a variety of preconditioners for the FETI-DP operator have been developed. However, there has not been any numerical study for the FETI-DP method, which compares those preconditioners on nonmatching grids while there have been a few papers for numerical study on the comparison of FETI preconditioners. Therefore, we present the numerical study of four different preconditioners for two-dimensional elliptic problems. The numerical results confirm the superiority of the preconditioner by Kim and Lee [1] for noncomparably nonmatching grids, while the superiority of the preconditioner by Dryja and Widlund [2] is confirmed for matching grids and comparably nonmatching grids. (C) 2006 Elsevier Ltd. All rights reserved.This work was partially supported by KRF-2001-041-D00038 and KOSEF R01-2000-00008
A new hydrate-based recovery process for removing chlorinated hydrocarbons from aqueous solutions
No full textThe main objective of this study was to check the feasibility of the newly proposed hydrate-based chlorinated hydrocarbon (CHC) recovery process for removing chlorinated hydrocarbons from aqueous solutions. Two key process variables of hydrate phase equilibria and formation kinetics were closely examined to develop the overall conceptual design of this technology. First, the ternary four-phase (H-L-W-L-CHC-V) hydrate equilibria of aqueous solutions containing methylene chloride (CH2Cl2), carbon tetrachloride (CCl4) 1,2-dichloroethane (CH2ClCH2Cl), 1,1,1-trichloroethane (CH3CCl3), and 1,1-dichloroethylene (CH2 = CCl2) were measured at various temperature and pressure conditions using three different types of help gases (CO2, N-2, CH4). The help gas + water + chlorinated hydrocarbons systems greatly reduced the hydrate-forming pressure, which confirmed the mixed hydrates with chlorinated hydrocarbons more stabilized than the simple hydrates consisting of a help gas and water. The degree of stabilization was found to follow the order of 1,2-dichloroethane < 1,1-dichloroethylene < methylene chloride <less than> 1,1,1-trichloroethane < carbon tetrachloride. For the N-2 + water + carbon tetrachloride system, the formation pressure reduction as much as 96% was observed at 279.35 K. Second, the formation kinetic experiments of carbon dioxide hydrates containing chlorinated hydrocarbons were conducted under isothermal and isobaric conditions. The consumption rate of carbon dioxide gas became fast at the early time of the growth period, gradually decreased, and finally went to the complete hydration. The proposed hydrate-based recovery process appears to be very simple from the operational point of view because no special facilities requiring sensitive and complex function are needed. Another advantage is that this process only requires carbon dioxide as a hydrate former. Best of all, this process can he applied to separation and recovery of other organic pollutants dissolved in aqueous solutions without changing the basic concept.This research was performed for the Greenhouse Gas
Research Center, one of the Critical Technology-21 Programs,funded by the Ministry of Science and Technology of Korea
and also partially supported by the Brain Korea 21 Project
Quantum cryptography using single-particle entanglement
No full text©2003 The American Physical Society
URL: http://link.aps.org/abstract/PRA/v68/e012324
DOI: 10.1103/PhysRevA.68.012324
PACS: 03.67.-a, 03.67.Dd, 03.67.LxA quantum cryptography scheme based on entanglement between a single-particle state and a vacuum state is proposed. The scheme utilizes linear optics devices to detect the superposition of the vacuum and single-particle states. Existence of an eavesdropper can be detected by using a variant of Bell's inequality.We acknowledge support by the Korea Research Foundation Grant No. KRF-2002-070-C00048. H. Lee and J. Kim were supported by the Korea Research Foundation (Grant No. KRF-2002-070-C00029)
Yield stress anomalous Behavior in beta-CuZn alloy
No full textseries of tensile and load relaxation behaviors in B2 type beta-CuZn alloy have been examined to clarify the strain rate & the temperature dependence of yield stress anomaly. As strain rate increased, the anomalous peak moved to a higher stress and temperature region. The anomalous yielding region below peak temperature (T-p) revealed slightly positive strain rate dependence, while the region above T-p showed considerably positive strain rate dependence. Based on the different tendency of temperature and strain rate dependence of anomalous yielding, two types of deformation modes were suggested and incorporated into the yield stress vs. temperature curve analysis, which was in accord well with the experimental results. The less sensitive strain rate dependence of yield stress anomaly indicated that the yield stress anomalous behavior in beta-CuZn alloy mainly seemed to be attributed to the vacancy hardening.110sciescopu
Sojourner, Spring 1985
No full textEditor: Sherry Lee. Production: Laura Blowers and Sherry Lee.University YW. (1985). Sojourner, Spring 1985. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/275156
Robustness of multiparty nonlocality to local decoherence
No full text©2006 The American Physical Society
URL: http://link.aps.org/abstract/PRA/v74/e062112
doi:10.1103/PhysRevA.74.062112
PACS: 03.65.Ud, 03.65.YzWe investigate the robustness of multiparty nonlocality under local decoherence, acting independently and equally on each subsystem. To be specific, we consider an N-qubit Greenberger-Horne-Zeilinger (GHZ) state under a depolarization, dephasing, or dissipation channel, and examine nonlocality by testing violation of the Mermin-Klyshko inequality, which is one of Bell's inequalities for multiqubit systems. The results show that the robustness of nonlocality increases with the number of qubits, and that the nonlocality of an N-qubit GHZ state with even N is extremely persistent against dephasing.The authors thank Jinhyoung Lee for helpful discussions. S.S.J. and J.W.K. appreciate the financial support from the Korea Ministry of Information and Communication. H.W.L. was supported by the Ministry of Science and Technology (MOST) of Korea through the Leading Basic S&T Research Projects
Sojourner, Fall 1984
No full textEditor/Production: Sherry Lee. Advisor: Rhonda MaderyUniversity YW. (1984). Sojourner, Fall 1984. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/275190
CYCLIC PLASTIC STRAIN-ENERGY AS A DAMAGE CRITERION AND ENVIRONMENTAL-EFFECT IN NB-BEARING HIGH-STRENGTH, LOW-ALLOY STEEL
No full textLow cycle fatigue behaviors in Nb-bearing high strength, low alloy (HSLA) steel have been studied at plastic strain amplitudes Delta epsilon(p)/2 ranging from 1x10(-5) to 1x10(-2) in air and in ultrahigh vacuum (UHV). Microcracks are initiated along slip lines both in air and in UHV, and grain boundaries act as effective barriers to the propagation of microcracks. Coffin-Manson relations are reasonably satisfied for the microcrack initiation life N-i and the fatigue life N-f both in air and in UHV. The accumulated total cyclic plastic strain energy W-i required for fatigue crack initiation and the accumulated total cyclic plastic strain energy W-f required for fatigue failure are expressed mathematically in the form of K(Delta epsilon(p)/2)(N). The computed values of W-i and W-f are in good agreement with the values determined experimentally. The vacuum environment enhances N-i, N-f, W-i and W-f. The environmental effect becomes greater as the plastic strain amplitude decreases.The authors would like to thank Dr. M. E. Fine of Northwestern University and Dr. S. P. Bhat and R. Cline of Inland Steel Research Laboratory for many helpful discussions
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