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排序方式: 共有4000条查询结果,搜索用时 321 毫秒
991.
煤的工业分析至元素分析的BP神经网络预测模型 总被引:8,自引:1,他引:7
以大量煤质分析数据为基础,建立了利用煤工业分析数据( 包括水份、灰份、挥发份及热值) 计算元素分析数据的BP神经网络预测模型,并将该模型与现有经验公式进行了比较,结果表明神经网络模型有很好的推广能力。可以满足工业应用的要求 相似文献
992.
993.
Liusheng Chen Ming Ni Shijun Jia Xigao Jin Shouren Ge Atsushi Takahara 《Journal of Macromolecular Science: Physics》2013,52(3):339-340
Abstract Atomic force microscopy (AFM) has been applied to observe single-chain polymethylmethacrylate (PMMA) particles that were stored for six months at room temperature after being sprayed from very dilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Nearly monodisperse PMMA standards of molecular weights ranging from 7.90 × 104 to 1.3 × 106 were used to investigate the effect of molecular weight (MW) on the size of the single-chain PMMA particles. These single-chain particles showed close to spherical shapes. The morphology of single-chain PMMA particles of a given molecular weight has found to be identical in spite of different solvents used for solution spraying. Molecular weight dependence of the particle dimension was also found. The diameters of single-chain PMMA particles after correction of tip-geometry effect were compared with the values estimated from molecular weight and density. 相似文献
994.
995.
996.
997.
JinYANG NiNaSHANG 《数学学报(英文版)》2003,19(1):35-38
In this paper, a necessary and sufficient condition concerning Huygens' principle for a family of hyperbolic equations is
given, and thus Stellmacher's result is extended. 相似文献
998.
Ion redistribution in an electric double layer 总被引:1,自引:0,他引:1
The structure of a single flat electric double layer (EDL) is studied by grounding a symmetric electrolyte (NaCl), which is in contact with a planar positively corona-treated polypropylene film. Because the profiles of the electrostatic potential distribution and ion distribution in the solution are altered when the solution is grounded, some mobile counterions in the diffuse layer of the electrolyte solution will go into the Helmholtz layer and thus decrease the electric potential psi(a/2) at the Stern plane in order to obtain a new equilibrium. After the system is grounded for a long time, the representation of the electric double layer changes from a Stern model to a Helmholtz model. Theoretical and experimental analyses are given in this study. 相似文献
999.
Discovery of inhibitors that elucidate the role of UCH-L1 activity in the H1299 lung cancer cell line 总被引:17,自引:0,他引:17
Liu Y Lashuel HA Choi S Xing X Case A Ni J Yeh LA Cuny GD Stein RL Lansbury PT 《Chemistry & biology》2003,10(9):837-846
Neuronal ubiquitin C-terminal hydrolase (UCH-L1) has been linked to Parkinson's disease (PD), the progression of certain nonneuronal tumors, and neuropathic pain. Certain lung tumor-derived cell lines express UCH-L1 but it is not expressed in normal lung tissue, suggesting that this enzyme plays a role in tumor progression, either as a trigger or as a response. Small-molecule inhibitors of UCH-L1 would be helpful in distinguishing between these scenarios. By utilizing high-throughput screening (HTS) to find inhibitors and traditional medicinal chemistry to optimize their affinity and specificity, we have identified a class of isatin O-acyl oximes that selectively inhibit UCH-L1 as compared to its systemic isoform, UCH-L3. Three representatives of this class (30, 50, 51) have IC(50) values of 0.80-0.94 micro M for UCH-L1 and 17-25 micro M for UCH-L3. The K(i) of 30 toward UCH-L1 is 0.40 micro M and inhibition is reversible, competitive, and active site directed. Two isatin oxime inhibitors increased proliferation of the H1299 lung tumor cell line but had no effect on a lung tumor line that does not express UCH-L1. Inhibition of UCH-L1 expression in the H1299 cell line using RNAi had a similar proproliferative effect, suggesting that the UCH-L1 enzymatic activity is antiproliferative and that UCH-L1 expression may be a response to tumor growth. The molecular mechanism of this response remains to be determined. 相似文献
1000.
José Niño-Mora 《Mathematical Programming》2002,93(3):361-413
This paper develops a polyhedral approach to the design, analysis, and computation of dynamic allocation indices for scheduling
binary-action (engage/rest) Markovian stochastic projects which can change state when rested (restless bandits (RBs)), based on partial conservation laws (PCLs). This extends previous work by the author [J. Ni?o-Mora (2001): Restless bandits, partial conservation laws and indexability.
Adv. Appl. Probab. 33, 76–98], where PCLs were shown to imply the optimality of index policies with a postulated structure in stochastic scheduling problems, under admissible linear objectives, and they were deployed to obtain simple sufficient conditions for the existence of Whittle's (1988) RB index (indexability), along with an adaptive-greedy index algorithm. The new contributions include: (i) we develop the polyhedral foundation
of the PCL framework, based on the structural and algorithmic properties of a new polytope associated with an accessible set system -extended polymatroid}); (ii) we present new dynamic allocation indices for RBs, motivated by an admission control model,
which extend Whittle's and have a significantly increased scope; (iii) we deploy PCLs to obtain both sufficient conditions
for the existence of the new indices (PCL-indexability), and a new adaptive-greedy index algorithm; (iv) we interpret PCL-indexability as a form of the classic economics law of
diminishing marginal returns, and characterize the index as an optimal marginal cost rate; we further solve a related optimal constrained control problem; (v) we carry out a PCL-indexability analysis of the motivating admission control model, under time-discounted
and long-run average criteria; this gives, under mild conditions, a new index characterization of optimal threshold policies;
and (vi) we apply the latter to present new heuristic index policies for two hard queueing control problems: admission control
and routing to parallel queues; and scheduling a multiclass make-to-stock queue with lost sales, both under state-dependent
holding cost rates and birth-death dynamics.
Received: April 2000 / Accepted: October 2002 Published online: December 9, 2002
RID="★"
ID="★" Work partly supported by the Spanish Ministry of Science and Technology (grant BEC2000-1027), NATO (Collaborative
Linkage Grant PST.CLG.976568), and the Joint Spanish-US (Fulbright) Commission for Scientific and Technical Exchange (project
2000-20132)
Key words. Markov decision process – restless bandits – polyhedral combinatorics – extended polymatroid – adaptive-greedy algorithm
– dynamic allocation index – stochastic scheduling – threshold policy – index policy – Gittins index – Klimov index – Whittle
index – control of queues – admission control – routing – make-to-stock – multiclass queue – finite buffers – conservation
laws – achievable performance
Mathematics Subject Classification (1991): (AMS 2000 Subject Classification): 90B36, 90B22, 90C40, 90C57, 90C08 相似文献