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排序方式: 共有206条查询结果,搜索用时 15 毫秒
1.
Laser-induced chemical vapour deposition of silicon films on SiO2/Si (1 0 0) and Si (1 0 0) substrates was studied using ArF laser irradiation of silane/argon gas mixture in parallel to the substrate. The optimal deposition conditions were specified by examination of film morphology at a wide range of irradiation and process parameters. At optimal conditions, specular films were obtained with no powder formation. The effect of deposition parameters, such as laser energy and repetition rate, on the deposition rate and the related film quality, was investigated. 相似文献
2.
Binoy Ravindran Peng Li Tamir Hegazy 《Journal of Parallel and Distributed Computing》2003,63(12):1219-1242
We present two proactive resource allocation algorithms, RBA*-FT and OBA-FT, for fault-tolerant asynchronous real-time distributed systems. The algorithms consider an application model where task timeliness is specified by Jensen's benefit functions and the anticipated application workload during future time intervals is described by adaptation functions. In addition, we assume that reliability functions of processors are available a priori. Given these models, our objective is to maximize aggregate task benefit and minimize aggregate missed deadline ratio in the presence of processor failures. Since determining the optimal solution is computationally intractable, the algorithms heuristically compute sub-optimal resource allocations, but in polynomial time. Experimental results reveal that RBA*-FT and OBA-FT outperform their non-fault-tolerant counterparts in the presence of processor failures. Furthermore, RBA*-FT performs better than OBA-FT, although OBA-FT incurs better worst-case and amortized computational costs. Finally, we observe that both algorithms robustly withstand errors in the estimation of anticipated failures. 相似文献
3.
There are pragmatic benefits to trait-consistent mood states, especially when people are evaluating new objects within the environment (M. Tamir, M. D. Robinson, & G. L. Clore, 2002). The present studies, involving both naturally occurring (Studies 1 and 2) and manipulated (Study 3) mood states, demonstrated such trait-consistent interactions within the context of neuroticism and negative mood states. Individuals high in neuroticism were faster to make evaluations when in a negative mood state like sadness. By contrast, individuals low in neuroticism were faster to make evaluations when in a neutral mood state. The present studies demonstrate that although negative mood states are hedonically unpleasant, they can be beneficial in some ways for individuals high in neuroticism. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
4.
k-Anonymity is a privacy preserving method for limiting disclosure of private information in data mining. The process of anonymizing
a database table typically involves generalizing table entries and, consequently, it incurs loss of relevant information.
This motivates the search for anonymization algorithms that achieve the required level of anonymization while incurring a
minimal loss of information. The problem of k-anonymization with minimal loss of information is NP-hard. We present a practical approximation algorithm that enables solving
the k-anonymization problem with an approximation guarantee of O(ln k). That algorithm improves an algorithm due to Aggarwal et al. (Proceedings of the international conference on database theory
(ICDT), 2005) that offers an approximation guarantee of O(k), and generalizes that of Park and Shim (SIGMOD ’07: proceedings of the 2007 ACM SIGMOD international conference on management
of data, 2007) that was limited to the case of generalization by suppression. Our algorithm uses techniques that we introduce herein for
mining closed frequent generalized records. Our experiments show that the significance of our algorithm is not limited only
to the theory of k-anonymization. The proposed algorithm achieves lower information losses than the leading approximation algorithm, as well
as the leading heuristic algorithms. A modified version of our algorithm that issues ℓ-diverse k-anonymizations also achieves lower information losses than the corresponding modified versions of the leading algorithms. 相似文献
5.
An electrochemical reactor operated with two identical solution streams injected in opposite directions on the same axis, and leaving it at a normal direction was studied by measuring local and global mass transfer coefficients and visualization of solution flow patterns. This flow configuration was compared to a case where a single stream enters the reactor and leaves it on the same axis. It was found that only the data obtained for the single stream mode can be correlated by the Chilton-Colburn relation, indicating a near laminar boundary layer flow. Global mass transfer coefficients for the single stream mode were found to be slightly higher than those for the interacting jets mode. However, when comparing the two modes by taking into account the dimensionless ratio of the mass transfer coefficient (Sh) to the energy consumption (Eu), it was found that the interacting jets (IJ) mode exhibits a better performance as compared to the single stream mode. The superiority of the IJ mode increases with increasing Reynold's number (Re).Nomenclature
A, B
adjustable parameters
-
b
half width of channel
-
C
electrolyte ion concentration
-
d
inlet pipe diameter
-
d
microelectrode diameter
-
D
diffusion coefficient
-
maximum value of mean deviation
-
E
pumping energy
-
Eu
Euler number
-
F
Faraday number
-
i
current to a single microelectrode on an active wall
-
i
current to a single microelectrode in an inert wall
-
I
global diffusion current
-
k
mass transfer coefficient to a single microelectrode in an active wall
-
k
mass transfer coefficient to a single microelectrode in an inert wall
-
K
global mass transfer coefficient
-
Q
volumetric flow rate
-
Q
T
total volumetric flow rate
-
R
radius of the electrochemical reactor
-
Re
Reynolds number
-
s
surface area of a microelectrode
-
S
surface area of the working electrode
-
Sc
Schmidt number
-
Sh
Sherwood number
-
V
x
axial flow velocity alongx-axis
-
V
flow velocity at large distance from the leading edge
-
V
mean flow velocity
-
x
axis tangential to the surface
-
y
axis normal to the surface
-
z
number of electrons transferred in the reaction (z=1 in the present case)
Greek letters
viscosity
-
specific gravity
-
kinematic viscosity (/)
- P
pressure drop across the reactor
- V
voltage drop across the reactor
Abbreviations ST
single stream
- IJ
interacting jets 相似文献
6.
GB Hagberg F Blomstrand M Nilsson H Tamir E Hansson 《Canadian Metallurgical Quarterly》1998,32(2):153-162
A two-step exocytosis/endocytosis protocol was used in rat pancreatic acini to study membrane trafficking events at the apical plasma membrane (APM) as a function of extracellular pH. Exocytosis, as measured by cholecystokinin (CCK)-8-induced release of amylase into the incubation medium, was relatively insensitive to changes in extracellular pH from 5.5 to 9.0. In contrast, endocytosis, as measured by temperature-dependent uptake of horseradish peroxidase (HRP), was robust at pH values between 6.5 and 8.3 but abolished at acidic pH values of 5.5 to 6.0. Energy metabolism and cell viability were maintained during pH 6-induced cessation of HRP uptake, and the vesicular block could be reversed upon raising the luminal pH to 7.4. Histochemical and morphometric studies of HRP uptake examined by electron microscopy indicated that extracellular pH regulates endocytosis at the apical plasma membrane. At pH 6.0 in prestimulated cells, HRP uptake at the APM was abolished, and acinar lumen membranes remained markedly dilated with decreased density of microvilli and "arrested" exocytic images. At pH 7.4, HRP was taken up into endolysosomal structures within the Golgi complex, and acinar lumen membranes were contracted. Cleavage of GP2, a glycosyl phosphatidylinositol-anchored protein, was associated with the pH-dependent activation of HRP uptake. These studies demonstrate that acinar lumen pH regulates endocytic but not exocytic activity at the APM and suggest that alkalinization of the acinar lumen by duct cells is required for retrieval of exocytic membranes into the acinar cell via vesicular uptake mechanisms. The role of acid-base interactions within the acinar lumen provides a novel basis for understanding the cellular and luminal defects observed within the exocrine pancreas in cystic fibrosis. 相似文献
7.
In this paper we introduce a minimax model unifying several classes of single facility planar center location problems. We
assume that the transportation costs of the demand points to the serving facility are convex functions {Q
i
}, i=1,…,n, of the planar distance used. Moreover, these functions, when properly transformed, give rise to piecewise quadratic functions
of the coordinates of the facility location. In the continuous case, using results on LP-type models by Clarkson (J. ACM 42:488–499,
1995), Matoušek et al. (Algorithmica 16:498–516, 1996), and the derandomization technique in Chazelle and Matoušek (J. Algorithms 21:579–597, 1996), we claim that the model is solvable deterministically in linear time. We also show that in the separable case, one can
get a direct O(nlog n) deterministic algorithm, based on Dyer (Proceedings of the 8th ACM Symposium on Computational Geometry, 1992), to find an optimal solution. In the discrete case, where the location of the center (server) is restricted to some prespecified
finite set, we introduce deterministic subquadratic algorithms based on the general parametric approach of Megiddo (J. ACM
30:852–865, 1983), and on properties of upper envelopes of collections of quadratic arcs. We apply our methods to solve and improve the complexity
of a number of other location problems in the literature, and solve some new models in linear or subquadratic time complexity. 相似文献
8.
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