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41.
B Weisser S Grüne R Burger H Blickenstorfer J Iseli SH Michelsen R Opravil S Rageth ER Sturzenegger P Walker 《Canadian Metallurgical Quarterly》1994,8(4):227-231
In a retrospective study of 50 consecutive children with posterior fossa tumors treated at Texas Children's Hospital, Houston, Tex., in 1989-1992, we evaluated perioperative factors which might influence the development of postoperative cerebrospinal fluid leaks. Factors analyzed included the presence of preoperative hydrocephalus, the institution of cerebrospinal fluid diversion, and the method of dural closure. No statistically significant impact on subsequent cerebrospinal fluid leakage was demonstrated. 相似文献
42.
In this investigation we consider the formation of Cooper pairs near the oxygen-deficient sites in Y-Ba-Cu-O ceramic superconductors which would give rise to an energy-dependent potential as seen by conduction charge carriers. It is shown that Cooper pairs could be formed under such conditions, resulting in a supercurrent. We use the Bogoliubov transformation technique to calculate the energy gap, the energy difference, and the transition temperature of the model superconductor using certain data obtained from previous experiments. Numerical analysis shows that the superconducting current can be explained by the presence of such oscillating Cooper pairs. 相似文献
43.
Sarala Arunagiri Yipkei Kwok Patricia J. Teller Ricardo A. Portillo Seetharami R. Seelam 《International journal of parallel programming》2014,42(1):165-197
Providing differentiated service in a consolidated storage environment is a challenging task. To address this problem, we introduce FAIRIO, a cycle-based I/O scheduling algorithm that provides differentiated service to workloads concurrently accessing a consolidated RAID storage system. FAIRIO enforces proportional sharing of I/O service through fair scheduling of disk time. During each cycle of the algorithm, I/O requests are scheduled according to workload weights and disk-time utilization history. Experiments, which were driven by the I/O request streams of real and synthetic I/O benchmarks and run on a modified version of DiskSim, provide evidence of FAIRIO’s effectiveness and demonstrate that fair scheduling of disk time is key to achieving differentiated service in a RAID storage system. In particular, the experimental results show that, for a broad range of workload request types, sizes, and access characteristics, the algorithm provides differentiated storage throughput that is within 10% of being perfectly proportional to workload weights; and, it achieves this with little or no degradation of aggregate throughput. The core design concepts of FAIRIO, including service-time allocation and history-driven compensation, potentially can be used to design I/O scheduling algorithms that provide workloads with differentiated service in storage systems comprised of RAIDs, multiple RAIDs, SANs, and hypervisors for Clouds. 相似文献
44.
Zirconia and yttria films were sputter deposited onto unheated fused silica substrates using a metal target and rare gas-oxygen discharges. Double-beam spectrophotometry was used to measure the transmission and reflection as a function of incident photon energy, E , from which the absorption coefficient, α( E ), was calculated. An indirect interband transition at E i = 4.70 eV and two direct interband transitions at E g1 = 5.17 eV and E g2 = 5.93 eV occur in monoclinic zirconia. Two direct interband transitions at E g1 = 5.07 eV and E g2 = 5.73 eV occur in cubic yttria. The absorption edge structure is modified when unusual phases, such as tetragonal zirconia, and zirconia and yttria with no longrange crystallographic order, are present. 相似文献
45.
Dongyu Zhao Fan Fan Vladimir G. Chigrinov Hoi Sing Kwok Ben Zhong Tang 《Journal of the Society for Information Display》2015,23(5):218-222
Nowadays, liquid crystal displays (LCDs) with light‐emission are considered as energy‐efficient devices and are promising alternatives to conventional LCDs. To realize such possibility, strong fluorescent materials with a dichroic properties are required. Aggregate‐induced emission (AIE) is an unusual photophysical phenomenon shown by some luminogenic materials that will be highly emissive in their aggregate state. In this work, we studied the AIE effect of a luminescent liquid crystalline molecule TPE‐PPE in our LC system as a luminophore dopant. The result showed the excellent AIE effect that higher concentration of luminogen in the nematic LC host induced stronger luminescent intensity. Through exposure of a photoisomeriable alignment material sulfonic‐dye‐1, the photopatterning of a light‐emitting LC device was achieved with the use of the TPE‐PPE/nematic LC mixture. 相似文献
46.
Abhishek K. Srivastava Vladimir G. Chigrinov Hoi Sing Kwok 《Journal of the Society for Information Display》2015,23(6):253-272
The ferroelectric liquid crystals, because of their fast electro‐optical response, are one of the most important classes of liquid crystals. Here, in this review, we have summarized the different electro‐optical modes for ferroelectric liquid crystals. Clark–Lagerwall effect (surface stabilized ferroelectric liquid crystal), deformed helix ferroelectric (DHF) effect, electrically suppressed helix (ESH) mode, DHF orientational Kerr effect, and ESH diffraction modes have been discussed. All of the crucial features, that is, optics, electro‐optics, dynamics, and their dependence on material parameters, operational regime, and applications, have been reviewed. 相似文献
47.
Ultra wideband (UWB) systems are considered as the key wireless infrastructure platforms for efficient short-range communications.
In particular, the UWB based mobile computing systems are envisioned to be attractive solutions to various ad hoc networking
applications. However, due to UWB’s unique physical characteristics, the traditional resource management schemes for ad hoc
networks cannot be applied to UWB based systems directly. In this paper, we consider the bandwidth scheduling problem in a
UWB based hierarchical wireless ad hoc network, which is typically used in an enterprise-scale mobile computing environment.
Based on the mathematical analysis and the computer simulations, it is demonstrated that our proposed scheduling scheme exhibits
close-to-optimal performance governed by the proportional fairness (PF) constraint. Moreover, a novel self-organized clustering
method is designed to improve the system throughput while meeting the PF constraint. Simulation results suggest that the proposed
clustering method is effective under various system configurations.
相似文献
Yu-Kwong KwokEmail: |
48.
Building Sparse Multiple-Kernel SVM Classifiers 总被引:1,自引:0,他引:1
The support vector machines (SVMs) have been very successful in many machine learning problems. However, they can be slow during testing because of the possibly large number of support vectors obtained. Recently, Wu (2005) proposed a sparse formulation that restricts the SVM to use a small number of expansion vectors. In this paper, we further extend this idea by integrating with techniques from multiple-kernel learning (MKL). The kernel function in this sparse SVM formulation no longer needs to be fixed but can be automatically learned as a linear combination of kernels. Two formulations of such sparse multiple-kernel classifiers are proposed. The first one is based on a convex combination of the given base kernels, while the second one uses a convex combination of the so-called ldquoequivalentrdquo kernels. Empirically, the second formulation is particularly competitive. Experiments on a large number of toy and real-world data sets show that the resultant classifier is compact and accurate, and can also be easily trained by simply alternating linear program and standard SVM solver. 相似文献
49.
The MatSeek system is an ontology-based federated search interface to key materials science databases and analytical tools. By combining Semantic Web and Web 2.0 technologies, MatSeek provides materials scientists with a single Web interface that enables them to search across disparate databases containing crystal-structure data, ionic-conductivity data, and phase stability data; render 3D crystal-structure images; calculate bond lengths and angles; retrieve relevant scholarly references; and identify potential new materials with the structure and properties required to satisfy specific applications. The MatOnto ontology underlying MatSeek enables integration of data across disparate databases, and Web 2.0 technologies enable iterative searching across the databases. The results retrieved from searching the previous database are used as input to the query on the next database. By providing materials scientists with a single, integrated Web interface to the critical materials science databases and analytical tools, MatSeek represents a significant advance toward a full-fledged materials-informatics workbench. 相似文献
50.
Mak B.K.-W. Tsz-Chung Lai Tsang I.W. Kwok J.T.-Y. 《IEEE transactions on audio, speech, and language processing》2009,17(7):1372-1381
This paper proposes a nonlinear generalization of the popular maximum-likelihood linear regression (MLLR) adaptation algorithm using kernel methods. The proposed method, called maximum penalized likelihood kernel regression adaptation (MPLKR), applies kernel regression with appropriate regularization to determine the affine model transform in a kernel-induced high-dimensional feature space. Although this is not the first attempt of applying kernel methods to conventional linear adaptation algorithms, unlike most of other kernelized adaptation methods such as kernel eigenvoice or kernel eigen-MLLR, MPLKR has the advantage that it is a convex optimization and its solution is always guaranteed to be globally optimal. In fact, the adapted Gaussian means can be obtained analytically by simply solving a system of linear equations. From the Bayesian perspective, MPLKR can also be considered as the kernel version of maximum a posteriori linear regression (MAPLR) adaptation. Supervised and unsupervised speaker adaptation using MPLKR were evaluated on the Resource Management and Wall Street Journal 5K tasks, respectively, achieving a word error rate reduction of 23.6% and 15.5% respectively over the speaker-independently model. 相似文献