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1.
Estimation of distribution algorithms (EDAs) are stochastic optimization techniques that explore the space of potential solutions by building and sampling explicit probabilistic models of promising candidate solutions. While the primary goal of applying EDAs is to discover the global optimum or at least its accurate approximation, besides this, any EDA provides us with a sequence of probabilistic models, which in most cases hold a great deal of information about the problem. Although using problem-specific knowledge has been shown to significantly improve performance of EDAs and other evolutionary algorithms, this readily available source of problem-specific information has been practically ignored by the EDA community. This paper takes the first step toward the use of probabilistic models obtained by EDAs to speed up the solution of similar problems in the future. More specifically, we propose two approaches to biasing model building in the hierarchical Bayesian optimization algorithm (hBOA) based on knowledge automatically learned from previous hBOA runs on similar problems. We show that the proposed methods lead to substantial speedups and argue that the methods should work well in other applications that require solving a large number of problems with similar structure. 相似文献
2.
Chao MW Lin CH Assa J Lee TY 《IEEE transactions on visualization and computer graphics》2012,18(5):729-740
The rapid growth of motion capture data increases the importance of motion retrieval. The majority of the existing motion retrieval approaches are based on a labor-intensive step in which the user browses and selects a desired query motion clip from the large motion clip database. In this work, a novel sketching interface for defining the query is presented. This simple approach allows users to define the required motion by sketching several motion strokes over a drawn character, which requires less effort and extends the users’ expressiveness. To support the real-time interface, a specialized encoding of the motions and the hand-drawn query is required. Here, we introduce a novel hierarchical encoding scheme based on a set of orthonormal spherical harmonic (SH) basis functions, which provides a compact representation, and avoids the CPU/processing intensive stage of temporal alignment used by previous solutions. Experimental results show that the proposed approach can well retrieve the motions, and is capable of retrieve logically and numerically similar motions, which is superior to previous approaches. The user study shows that the proposed system can be a useful tool to input motion query if the users are familiar with it. Finally, an application of generating a 3D animation from a hand-drawn comics strip is demonstrated. 相似文献
3.
Creswell LL Wyers SG Pirolo JS Perman WH Vannier MW Pasque MK 《IEEE transactions on medical imaging》1992,11(4):581-589
A hybrid three-dimensional solid mathematical model of cardiac ventricular geometry developed using magnetic resonance (MR) images of an in vivo canine heart is discussed. The modeling techniques were validated using MR images of an ex vivo heart and direct measurements of cardiac geometry and mass properties. A spin-echo MR sequence with in-plane resolution of 1.0 mm was used to image the canine heart in eleven short-axis planes at contiguous 5-mm intervals. Contour points on the epicardial, left ventricle (LV), and right ventricle (RV) boundaries were selected manually at each slice level. A boundary representation geometric model was constructed by fitting third-order nonuniform rational B-spline surfaces through each set of surface points. Compared to the anatomic specimen (AS), volume errors of the ex vivo model were 0.3, 1.5, and 5.8% for the LV cavity, RV cavity, and total enclosed volumes, respectively. Comparison of cross-sectional areas of the AS and the model at ten levels demonstrated mean model errors of 4.1, 2.5, and 2.9% for the LV, RV, and epicardial boundaries, respectively 相似文献
4.
5.
The design of a three-channel solar radiometer used to determine total columnar atmospheric water-vapor amounts is presented. The main channel is located in the 0.94-μm water-vapor band, and two other channels are located in adjacent nonabsorption regions of the solar spectrum and are used to remove scattering effects from the main channel. Water-vapor transmittance is determined by means of a modified Langley approach, and these transmittances are converted to columnar water vapor by means of a band model developed at the University of Arizona. Several cases are presented in which columnar water-vapor amounts are determined through the use of the instrument and method described here. These results are compared with sounding-balloon results. Tests of the method indicate that columnar water vapor may be retrieved with an uncertainty of less than 10%. 相似文献
6.
The development and modeling of a liquid-crystal phase grating for real-time diffractive three-dimensional displays are discussed. The system being developed, which is called the ICVision system, utilizes a number of ideas that will result in a rugged, low-power three-dimensional display offering both vertical and horizontal parallax and eventually full color. Fringing fields created between interdigitated electrodes formed on top of VLSI die will induce a diffraction pattern in a thin layer of liquid crystal that will cover the die. A detailed electrostatic and diffraction analysis of liquid-crystal phase-grating regions that will make up the final display is given here. The electrostatic analysis is developed by use of the method of moments. The diffraction analysis is developed by use of rigorous coupled-wave diffraction theory. The numerical results obtrained from the mathematical model are compared with experimental diffraction results from preliminary LCD cells that have been assembled as prototype ICVision devices. 相似文献
7.
Liquid crystal-on-silicon implementation of the partial pixel three-dimensional display architecture
Nordin GP Kulick JH Lindquist RG Nasiatka PJ Jones MW Friends M Kowel ST 《Applied optics》1995,34(19):3756-3763
We report the implementation of a liquid crystal-on-silicon, three-dimensional (3-D) diffractive display based on the partial pixel architecture. The display generates multiple stereoscopic images that are perceived as a static 3-D scene with one-dimensional motion parallax in a manner that is functionally equivalent to a holographic stereogram. The images are created with diffraction gratings formed in a thin liquid crystal layer by fringing electric fields from transparent indium tin oxide interdigitated electrodes. The electrodes are controlled by an external drive signal that permits the 3-D scene to be turned on and off. The display has a contrast ratio of 5.8, which is limited principally by optical scatter caused by extraneous fringing fields. These scatter sources can be readily eliminated. The display reported herein is the first step toward a real-time partial pixel architecture display in which large numbers of dynamic gratings are independently controlled by underlying silicon drive circuitry. 相似文献
8.
A scheme for distance and velocity signal detection is implemented. This technique is based on a laser diode with its frequency modulated by a triangular waveform and followed by time gating. 相似文献
9.
Fleet ML Simske SJ Hoehn A Schmeister TA Luttges MW 《Microgravity science and technology》1995,8(1):62-67
The Animal Module for Autonomous space Support (A-MASS) was developed to enable 30-day spaceflight for mice on the first Commercial Experiment Transporter mission. Because space hardware did not previously exist to support mice without astronaut intervention, the A-MASS presented considerable technical and animal care challenges. The technical challenges included maintaining a 42.5l payload volume and 20-g structural conformance while providing 30 days of autonomous mouse support. Sensors, video, a pressurized oxygen supply system and an internal data logging system were incorporated. The A-MASS met NIH guidelines for temperature, humidity, food and water access, oxygen supply, air quality and odor control. These technical and animal care challenges, along with power and mass constraints, were addressed using a novel design which ensures a fresh food and water supply, a clean view path into the cage for the camera system, and removal of the wastes from the air supply. The payload was successfully tested in an enclosed chamber and passed animal health, vibrational, mechanical, and electrical tests. The physiological, tactical and animal support information gathered will be applicable to the development of mouse support modules for the Shuttle Middeck and Space Station Freedom Express Rack environments. 相似文献
10.
The ability of ultraviolet resonance Raman spectroscopy (UVRRS) to determine structural, environmental, and analytical information concerning low-concentration aqueous biomolecules makes it a powerful bioanalytical and biophysical technique. Unfortunately, its utility has been limited by experimental requirements that preclude in situ or in vivo studies in most cases. We have developed the first high-performance fiber-optic probes suitable for long-term use in pulsed UVRRS applications in the deep- UV (DUV, 205-250 nm). The probes incorporate recently developed improved ultraviolet (IUV) fibers that do not exhibit the rapid solarization and throughput decay that previously hampered the use of optical fibers for delivering pulsed, DUV light. A novel 90 degrees mirrored collection geometry is used to overcome the inner-filtering effects that plague flush-probe geometries. The IUV fibers are characterized with respect to their efficacy at transmitting pulsed, DUV laser light, and prototype probes are used to obtain pulsed UVRRS data of aromatic amino acids, proteins, and hormones at low concentrations with 205-240-nm pulsed excitation. Efficient probe geometries and fabrication methods are presented. The performance of the probes in examining resonance-enhanced Raman signals from absorbing chromophores is investigated, and the optimal excitation wavelength is shown to be significantly red-shifted from the maximum of the resonance Raman enhancement profile. Generally applicable procedures for determining optimal experimental conditions are also introduced. 相似文献