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181.
Tumageanian A. Keyhani A. Seung-Ill Moon Leksan T.I. Longya Xu 《Industry Applications, IEEE Transactions on》1994,30(2):433-439
A time-domain system identification procedure to estimate the parameters of a 5 kVA salient pole synchronous machine from standstill test measurements is proposed. The test consists of a DC flux decay signal applied to the d-axis and q-axis of the machine. From the recorded responses to this signal, the admittance transfer function models and the standstill frequency response equivalent circuit models are identified. The maximum likelihood algorithm is used to estimate the model parameter values, and the Akaike Criterion is used to select the best-fit model. The performance of the standstill models in the dynamic environment is studied through simulation of an on-line small-disturbance test. The results are compared with measured data 相似文献
182.
The distribution ratio of zinc between Ag‐Zn and Fe‐Zn alloys was measured to clarify the thermodynamic behaviour of zinc in Fe‐C melt at high temperatures. Also, the distribution ratio between Ag‐Zn alloy and CaO‐FeO‐CaF2 slag was measured to understand the dissolution mechanism of zinc in molten slags. The activity coefficient of zinc in Ag‐Zn alloy was preliminarily measured as a fundamental thermodynamic data for the activity of zinc in Fe‐C melt. From the dependence of the activity coefficient of zinc in Fe‐C melts on temperature and carbon content, the following equation could be obtained at 1473 ‐ 1623 K: The distribution ratio of zinc between Ag‐Zn alloy and CaO‐FeO‐CaF2 slag increased by increasing both the oxygen potential and slag basicity. The stoichiometric coefficients of the dissolution reaction were obtained by considering the relationship between zinc distribution ratio and slag basicity or oxygen partial pressure, when one of these two independent variables was fixed. The dissolution reaction of zinc into the slags could be described as follows: 相似文献
183.
LED‐backlight feedback control system with integrated amorphous‐silicon color sensor on an LCD panel
Ki‐Chan Lee Seung‐Hwan Moon Brian Berkeley Sang‐Soo Kim 《Journal of the Society for Information Display》2006,14(2):161-168
Abstract— Thin‐film‐transistor liquid‐crystal displays (TFT‐LCDs) have the largest market share of all digital flat‐panel displays. An LCD backlighting system employing a three‐color red‐green‐blue light‐emitting diode (RGB‐LED) array is very attractive, considering its wide color gamut, tunable white point, high dimming ratio, long lifetime, and environmental compatibility. But the high‐intensity LED has problems with thermal stability and degradation of brightness over time. Color and white luminance levels are not stable over a wide range of temperature due to inherent long‐term aging characteristics. In order to minimize color point and brightness differences over time, optical feedback control is the key technology for any LED‐backlight system. In this paper, the feasibility of an optical color‐sensing feedback system for an LED backlight by integrating the amorphous‐silicon (a‐Si) color sensor onto the LCD panel will be presented. To minimize the photoconductivity degradation of a‐Si, a new laser exposure treatment has been applied. The integrated color‐sensor optical‐feedback‐controlled LED‐backlight system minimized the color variation to less than 0.008 Δu'v' (CIE1976) compared to 0.025 for an open‐loop system over the temperature range of 42–76°C. 相似文献
184.
Practical crack control during the construction of precast segmental box girder bridges 总被引:3,自引:0,他引:3
Cracks that occurred in the bottom slab of a precast segmental bridge were investigated through a construction sequence analysis, which revealed that the cracks were caused by excessive deformation during temporary post-tensioning while joining the segments. In addition, a parametric study was performed to evaluate the effects of the prestressing sequence, bottom slab thickness, and position of the prestressing anchors. The structural behavior of the girder sections was greatly affected by the thickness of the bottom slab and the position of prestressing anchors, but not by the prestressing sequence. Based on the results, a construction method that prevents the cracks is proposed. 相似文献
185.
Java supports the monitor construct for language‐level synchronization in the context of multi‐threading. This paper introduces the lightweight monitor, an efficient user‐level monitor implementation. The lightweight monitor is useful for single‐threaded Java programs as well as for multi‐threaded Java programs with little lock contention. A 32‐bit lock is embedded in each object for efficient lock access while other monitor data structures are managed using a hash table. We highly optimized the lock manipulation code, which is translated and inlined by a just‐in‐time (JIT) compiler. In the most probable cases, only nine SPARC instructions are spent for lock acquisition and five instructions are spent for lock release. Our experimental results indicate that the lightweight monitor is faster than the monitor implementation in the SUN JDK 1.2 RC1 by up to 21 times in the absence of lock contention and by up to seven times in the presence of lock contention. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
186.
Y. H. Kim D. G. Moon W. K. Kim J. I. Han 《Journal of the Society for Information Display》2005,13(10):829-833
Abstract— A high‐performance polymer thin‐film transistor fabricated on a paper substrate has been demonstrated. As a water barrier layer, parylene was coated on a paper substrate by using a vacuum deposition process. Using poly (3‐hexylthiophene) as an active layer, a polymer thin‐film transistor with a field‐effect mobility of up to 0.086 cm2/V‐sec and an on/off ratio of 104 was achieved. The fabrication of a polymer thin‐film transistor built on an inexpensive paper substrate is expected to open a channel for future applications in flexible and disposable electronics with extremely low cost. 相似文献
187.
Moon Gi Cho Kyung Wook Paik Hyuck Mo Lee Seong Woon Booh Tae-Gyu Kim 《Journal of Electronic Materials》2006,35(1):35-40
The interfacial reaction between 42Sn-58Bi solder (in wt.% unless specified otherwise) and electroless Ni-P/immersion Au was
investigated before and after thermal aging, with a focus on the formation and growth of an intermetallic compound layer,
consumption of under bump metallurgy (UBM), and bump shear strength. The immersion Au layer with thicknesses of 0 μm (bare
Ni), 0.1 μm, and 1 μm was plated on a 5-μm-thick layer of electroless Ni-P (with 14–15 at.% P). The 42Sn-58Bi solder balls
were then fabricated on three different UBM structures by using screen printing and pre-reflow. A Ni3Sn4 layer formed at the joint interface after the pre-reflow for all three UBM structures. On aging at 125°C, a quaternary phase,
identified as Sn77Ni15Bi6Au2, was observed above the Ni3Sn4 layer in the UBM structures that contain Au. The thick Sn77Ni15Bi6Au2 layer degraded the integrity of the solder joint, and the shear strength of the solder bump was about 40% less than the nonaged
joints. 相似文献
188.
Byung S Kim Sun K Yoo Moon H Lee 《IEEE transactions on information technology in biomedicine》2006,10(1):77-83
The delay performance of compression algorithms is particularly important when time-critical data transmission is required. In this paper, we propose a wavelet-based electrocardiogram (ECG) compression algorithm with a low delay property for instantaneous, continuous ECG transmission suitable for telecardiology applications over a wireless network. The proposed algorithm reduces the frame size as much as possible to achieve a low delay, while maintaining reconstructed signal quality. To attain both low delay and high quality, it employs waveform partitioning, adaptive frame size adjustment, wavelet compression, flexible bit allocation, and header compression. The performances of the proposed algorithm in terms of reconstructed signal quality, processing delay, and error resilience were evaluated using the Massachusetts Institute of Technology University and Beth Israel Hospital (MIT-BIH) and Creighton University Ventricular Tachyarrhythmia (CU) databases and a code division multiple access-based simulation model with mobile channel noise. 相似文献
189.
190.
In this paper, we deal with an assembly line production system in which an automated guided vehicle (AGV) delivers parts to each workstation of assembly lines from a miniload automated storage/retrieval system (AS/RS). Each assembly production line is characterized by a sequence of workstations linked together for the production of a given type of product. We consider simultaneously the design problem of miniload AS/RS and the problem of determining a unit load size of the AGV. First, a non-linear mathematical model is formulated under a proposed AGV dispatching policy. And then, we determine an appropriate sequence of lines of the vehicle visits. Finally, based on the characteristics of the objective function and feasible region of the decision variables, a heuristic solution procedure is developed to find a near optimal solution. To examine the validity of the model, an example problem is solved. 相似文献