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921.
We propose a method to implement a speckle-reduced coherent three-dimensional (3D) display system by a combination of integral imaging and photorefractive volume holographic storage. The 3D real object is imaged through the microlens array and stored in the photorefractive crystal. During the reconstruction process a phase conjugate reading beam is used to minimize aberration, and a rotating diffuser located on the imaging plane of the lens array is employed to reduce the speckle noise. The speckle-reduced 3D image with a wide viewing angle can be reconstructed by use of the proposed system. Experimental results are presented and optical parameters of the proposed system are discussed in detail. 相似文献
922.
A new approach to rapidly produce micrometer-scale sensor elements into reusable multianalyte chemical sensor arrays is demonstrated. By using pin printing technology in concert with sol-gel processing methods, we form discrete xerogel-based microsensors on a planar substrate. We illustrate the new approach by forming discrete 02- and pH-responsive sensing elements into arrays that allow one to simultaneously determine O2 and pH in aqueous samples. The pin printing method allows one to prepare sensor elements that are on the order of 100 microm in diameter, 1-2 microm thick, at a rate of approximately one sensor element per second with a single pin. Within a given calibrated array, the sensor element-to-sensor element response is reproducible to within 5%, the sensor element short- and long-term reproducibilities are 3 and 6%, respectively, and the array-to-array response reproducibility is 11%. These results demonstrate the potential of this methodology for rapidly forming ensembles of reusable sensor arrays for simultaneous multianalyte detection. 相似文献
923.
A new, to our knowledge, two-dimensional phase-unwrapping algorithm is proposed. The algorithm, which is based on the global continuity of physical information (e.g. the three-dimensional surface profile of an object) being measured, uses the principle of least-phase difference to rectify errors caused by an erroneous 2pi-phase jump in the initial unwrapped phase map obtained by the conventional phase-unwrapping method. Experimental results show that the proposed algorithm works well on a phase map that contains error sources, such as noises, phase discontinuity of more than pi, and insufficient sampling. Moreover, the algorithm is most suitable for unwrapping a phase map generated during shape measurement with a step-change surface on the test object, which is usually a critical problem in shape measurement. 相似文献
924.
An optical method has been developed to measure the deformation of a membrane in a microphone. A fringe projector that consists of an optical fiber and an optical wedge is described and analyzed by geometric optics. A three-step phase-shifting technique that involves the introduction of an arbitrary phase is discussed. The fine fringe patterns projected onto a small test surface are captured by a CCD camera mounted on a long-distance microscope. With the aid of a phase-shifting technique and signal-demodulating techniques, the proposed setup is capable of measuring deformation of the membrane of the order of as much as submicrometers. 相似文献
925.
J. Cho C.-M. Wang H. M. Chan J. M. Rickman M. P. Harmer 《Journal of Materials Science》2002,37(1):59-64
Oversized rare-earth dopant ions such as Y3+, Nd3+, and La3+ segregate to grain boundaries and reduce the tensile creep rate of -Al2O3 by 2-3 orders of magnitude. It has been speculated that these dopant ions can modify the grain boundary structure in alumina by promoting the formation of special grain boundaries. If this were indeed the case, it would provide a possible explanation for the aforementioned creep rate retardation. In order to test this hypothesis, electron backscatter diffraction (EBSD) has been used to assess both the proportion of coincidence-site lattice boundaries, and the grain boundary misorientation distribution, in aluminas doped with various ions (Zr, Y, Nd, La, Nd/Zr). The results show that the grain boundary structure in alumina is not significantly altered by the addition of the above dopants, implying that the change in grain boundary chemistry is primarily responsible for the observed creep behavior. 相似文献
926.
T. Zhang K. K. Choi S. Rahman K. Cho P. Baker M. Shakil D. Heitkamp 《Structural and Multidisciplinary Optimization》2006,32(4):327-345
A hybrid method for robust and efficient optimization process is developed by integrating a new response surface method and pattern search algorithm. The method is based on: (1) multipoint approximations of the objective and constraint functions, (2) a multiquadric radial basis function (RBF) for the zeroth-order function approximation and a new RBF plus polynomial-based moving least-squares approximation for the first-order enhanced function approximation, and (3) a pattern search algorithm to impose a descent condition and applied adaptive subregion management strategy. Several numerical examples are presented to illustrate accuracy and computational efficiency of the proposed method for both function approximation and design optimization. To demonstrate the effectiveness of the proposed hybrid method, it is applied to obtain optimum designs of a microelectronic packaging system. A two-stage optimization approach is proposed for the design optimization. The material properties of microelectronic packaging system and the shape parameters of solder ball are selected as design variables. Through design optimization, significant improvements of durability performances are obtained using the proposed hybrid optimization method. 相似文献
927.
Dae Sung Yoon Yoon-Kyoung Cho Kwang W. Oh Sunhee Kim Young Ah Kim Jung Im Han Geunbae Lim 《Microsystem Technologies》2006,12(3):238-246
We have fabricated a microfluidic gel valve device that used reversible sol–gel transition of methyl cellulose (MC). A microheater
and a microtemperature sensor were implemented in each microchannel in the gel valve device. Before evaluating the performance
of the gel valve device, various properties of the MC solution were investigated using viscometer, spectrophotometer, and
NMR. Gelation temperature was increased as the MC concentration was increased. Clear gel, an intermediate state between clear
sol and turbid gel, was found at the temperature range from 30–40°C to 50–60°C. Temperature at each microchannel of the device
was measured and the effect of the temperature difference on the valve operation was elucidated. In order to have normal operation
of the gel valve, it was important to keep the temperature of the heated microchannel around 60°C while keeping the temperature
of the flowing microchannel below 35°C. The temperature difference between two microchannels was about 23 K when fan forced
cooling (FFC) method was used. For normal performance of the gel valve device, a temporary pause of fluid flow for at least
5 s was required to complete the local gelation in the microchannel. Stable gel valve performance was obtained at the flow
rates larger than 5 μl/min. The gel valve device showed no leakage up to 2.07×104 Pa. 相似文献
928.
In utility‐driven cluster computing, cluster Resource Management Systems (RMSs) need to know the specific needs of different users in order to allocate resources according to their needs. This in turn is vital to achieve service‐oriented Grid computing that harnesses resources distributed worldwide based on users' objectives. Recently, numerous market‐based RMSs have been proposed to make use of real‐world market concepts and behavior to assign resources to users for various computing platforms. The aim of this paper is to develop a taxonomy that characterizes and classifies how market‐based RMSs can support utility‐driven cluster computing in practice. The taxonomy is then mapped to existing market‐based RMSs designed for both cluster and other computing platforms to survey current research developments and identify outstanding issues. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
929.
Jae‐Hoon Lee Woo‐Jin Nam Hee‐Sun Shin Min‐Koo Han Yong‐Min Ha Hong‐Seok Choi Chang‐Hwan Lee Soon Kwang Hong 《Journal of the Society for Information Display》2006,14(4):411-417
Abstract— A novel active‐matrix organic light‐emitting‐diode (AMOLED) display employing a new current‐mirror pixel circuit, which requires four‐poly‐Si TFTs and one‐capacitor and no additional signal lines, has been proposed and sucessfully fabricated. The experimental results show that a new current mirror can considerably compensate luminance non‐uniformity and scale down a data current more than a conventional current‐mirror circuit in order to reduce the pixel charging time and increase the minimum data current. Compared with a conventional two‐TFT pixel, the luminance non‐uniformity induced by the grain boundaries of poly‐Si TFTs can be decreased considerably from 41% to 9.1%. 相似文献
930.
Junichiro Yoshimoto Masaya Nishimura Yoichi Tokita Shin Ishii 《Artificial Life and Robotics》2005,9(2):67-71
Reinforcement learning (RL) has been applied to constructing controllers for nonlinear systems in recent years. Since RL methods do not require an exact dynamics model of the controlled object, they have a higher flexibility and potential for adaptation to uncertain or nonstationary environments than methods based on traditional control theory. If the target system has a continuous state space whose dynamic characteristics are nonlinear, however, RL methods often suffer from unstable learning processes. For this reason, it is difficult to apply RL methods to control tasks in the real world. In order to overcome the disadvantage of RL methods, we propose an RL scheme combining multiple controllers, each of which is constructed based on traditional control theory. We then apply it to a swinging-up and stabilizing task of an acrobot with a limited torque, which is a typical but difficult task in the field of nonlinear control theory. Our simulation result showed that our method was able to realize stable learning and to achieve fairly good control.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004 相似文献