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排序方式: 共有7827条查询结果,搜索用时 15 毫秒
61.
《Journal of Process Control》2014,24(8):1260-1272
This study adapts the advanced step NMPC framework to Economic NMPC. Here, sufficient conditions for nominal stability are derived for NMPC controllers that incorporate economic stage costs with appropriate regularization. To guarantee these conditions, we derive a constructive strategy to calculate the regularization term directly. Moreover, we extend the sensitivity components in the advanced step NMPC framework to consider a rigorous path-following algorithm. This approach accounts for active set changes and allows much weaker constraint qualifications. Moreover, using an ℓ1 formulation of the NMPC problem satisfies these constraint qualifications and allows more reliable solution of the moving horizon optimization problem, even in the presence of noise. Finally, all of these concepts are demonstrated on a detailed case study with a continuously stirred tank reactor. 相似文献
62.
63.
Buckling of jets in electrospinning 总被引:1,自引:0,他引:1
Various buckling instabilities of electrospinning jets were observed and compared with the buckling instabilities of uncharged fluid jets. Buckling instability arises due to jet compression at impingement on a collector surface and occurs independently of the electrical bending instability. The velocity, diameter, density and viscosity of the electrospinning jets are the key factors that determine the buckling frequency. The electrically charged jets impinging onto grounded, horizontal or inclined (wedge-like) electrodes moving laterally at a constant velocity are studied experimentally. Straight and bending (electrospinning) jets emerge at short and sufficiently long inter-electrode distances, respectively. The experiments show that both straight segment and bending jets, when impinging onto a counter-electrode, buckled and produced patterns of meandering deposits. In the case of bending electrospun jets these short-length buckling patterns were superimposed on the bending loops found in the deposits. Buckling-related and bending-related morphologies are easily distinguishable. The buckling patterns have frequencies of the order of 105-106 Hz, whereas the bending loops are formed at the frequencies of the order of 103 Hz. The deposited buckling patterns include sinuous, zigzag-like, figures-of-eight, recurring curves, coiled and other structures that resembled many patterns created by uncharged jets of highly viscous fluids impinging a hard flat surface. In addition, several new morphologies which were not observed before with uncharged jets were found. The experimentally measured frequencies of the buckling patterns were compared to the theoretical predictions and a reasonable agreement was found. 相似文献
64.
M. Boudart 《Topics in Catalysis》1994,1(3-4):405-414
This is a personal account of the Havreholm Conference with a choice of topics dealing with catalytic ammonia synthesis. Among the general concepts that were retained are: the rate determining step with rates of adsorption and desorption of nitrogen; the direct activated dissociative adsorption of N2; the surface crystalline anisotropy of iron; the role of promoters in industrial iron based catalysts; and the atomic structure of the metallic surface on the industrial multiply promoted catalyst. Finally, a new isotope jump technique to measure an upper limit to the real turnover frequency is discussed. 相似文献
65.
66.
In this paper we focus on two complementary approaches to significantly decrease pre-training time of a deep belief network (DBN). First, we propose an adaptive step size technique to enhance the convergence of the contrastive divergence (CD) algorithm, thereby reducing the number of epochs to train the restricted Boltzmann machine (RBM) that supports the DBN infrastructure. Second, we present a highly scalable graphics processing unit (GPU) parallel implementation of the CD-k algorithm, which boosts notably the training speed. Additionally, extensive experiments are conducted on the MNIST and the HHreco databases. The results suggest that the maximum useful depth of a DBN is related to the number and quality of the training samples. Moreover, it was found that the lower-level layer plays a fundamental role for building successful DBN models. Furthermore, the results contradict the pre-conceived idea that all the layers should be pre-trained. Finally, it is shown that by incorporating multiple back-propagation (MBP) layers, the DBNs generalization capability is remarkably improved. 相似文献
67.
A. V. Fedorov 《Combustion, Explosion, and Shock Waves》2004,40(1):17-31
A review is made of uptodate investigations in the field of physicomathematical modeling of mixing of solid particles with highvelocity gas flows arising under the action on shock waves, compression waves, and expansion waves on unstable dust deposits on the boundaries of channels or plates and in cavities, as well as on free clouds of particles. In particular, experiments in shock tubes with particles initially located in cavities and on surfaces are described. The experimental data presented in the form of distributions of particle concentrations at various points of space above the unstable layer, pressure distributions on the lower wall of the shock tube, etc., are used for verification of proposed mathematical models in regimes of single particles, interacting continua, and turbulent diffusion. An analysis of experimental and numerical data shows that the models considered sometimes allow adequate identification of the wave structure of motion of the mixture and the field of parameters inside and outside the layer. 相似文献
68.
大开口高承载网格加筋壳的设计与工艺 总被引:1,自引:0,他引:1
本文采用有限元法计算了承受高轴压和外压作用下的大开口复合材料纵横密加筋壳的稳定性,得出不同铺层角度、不同受力工况下的大开口圆柱壳的临界载荷,并采用1:1试验件进行试验验证,将计算值与实验值进行了比较;对大开口复合材料纵横密加筋壳的缠绕工艺进行了研究,解决了大开口网格加筋壳开口补强的一次成型技术和密筋及开口部分的多丝嘴、无增量、非线性机械化缠绕成型工艺技术。 相似文献
69.
一步法光致变色EVA夹层玻璃的生产 总被引:1,自引:0,他引:1
主要阐述了一步法生产光致变色夹层玻璃的方法及过程,介绍了生产中应注意的事项及生产设备. 相似文献
70.
Deconvolution of the electrolytic manganese dioxide (EMD) discharge curve has indicated the presence of a number of energetically different reduction processes. This has been used to determine the contribution of each reduction process to the total discharge. Using step potential electrochemical spectroscopy (SPECS), the i-t data were modelled as the sum of the discharge of the individual reduction processes. From this, A√ D for each reduction process as a function of degree of discharge was determined. The maximum A√ D values for each process ranged from 2.3×10−2 to 4.0×10−4 cm3 s−1/2 g−1 values are consistent with previously reported values for A√ D, although in this case we have determined values for the entire compositional range. 相似文献