Multiscales and cascading in isotropic turbulence

The explicit mapping method is used to analyze the nonlinear dynamical behavior for cascade in isotropic turbulence. This deductive scale analysis is shown to provide the first visual evidence of the celebrated Richardson-Kolmogorv cascade, and reveals in particular its multiscale character based on the statistical solutions of Navier-Stokes equations. The results also indicate that the energy cascading process has remarkable similarities with the deterministic construction rules of the logistic map. Cascade of period-doubling bifurcations have been seen in this isotropic turbulent system that exhibit chaotic behavior. The "cascade" appears as an infinite sequence of period-doubling bifurcations.     

Cascade algorithm and multiresolution analysis on the Heisenberg group

In this paper we investigate the relationship between the convergence of cascade algorithm and orthogonal (or biorthogonal) multiresolution analysis on the Heisenberg group. It is proved that the (strong) convergence of cascade algorithm together with the perfect reconstruction condition induces an orthogonal multiresolution analysis and vice versa. Similar results are also proved for biorthogonal multiresolution analysis.     

A new approach of cascade utilization of the chemical energy of fuel

The indirect release of chemical energy of fuel is investigated, and a new mechanism is proposed to identify the cascade utilization of chemical energy of fuel more clearly. Based on the concept of energy level, the internal phenomenon of the indirect chemical energy release is disclosed, and the equations of energy level describing the utilization of chemical energy and thermal energy during the indirect chemical energy release process are obtained. From theoretical analysis, we find that the superiority of the indirect chemical energy release of fuel comes from the cascade utilization of the fuel's chemical energy. Moreover, the cascade utilization of chemical energy is verified by the investigation of CRGT (chemically recuperated gas turbine). As a result, the thermal exergy obtained from the chemical energy release of fuel increases by 2%?3%. The results obtained here may help a deeper understanding of indirect chemical energy release of fuel and provide a theoretical basis for the synthesis of innovative energy systems.     

Study of GaAIAs／GaAs Planar Lightwave Filters

Based on the theory of four-port resonator filters, the characteristics of four kinds of filters with single race-track, dual race-track, rectangular and MMI resonators respectively were numerically simulated by utilizing two-dimensional FDTD method. The relationship between the number of cascade resonators and the filtering features was also analyzed. A kind of narrow-band filters with four cascade resonators implemented on GaA1As/GaAs planar lightwave circuits were designed and fabricated. The measurement result shows that the half-width of such filters is about 10nm, which coincides well with the numeric computation.     

The real time cascade generalized predictive control and application to a boiler circuit system

Boiler-circuit system in a circulating fluidized bed conrbustion boiler is a complex and typical industrial process with a large lag and time-delay. Conventional PID algorithm can not obtain satisfied performance, especially in the presence of disturbance. A cascade generalized predictive control (CGPC) strategy, is which the inner loop can restrain the disturbance while the outer loop can eliminate the offset, is proposed in this paper. We develop cascade GPC algorithm instead of conventional PID algorithm in the boiler-circuit system. Simulation on experimental boiler-circuit models of circulating fluidized bed combustion boiler shows strong robustness.     

Decentralized closed-loop identification and controller design for a kind of cascade processes

A new decentralized closcd-loop identification and predictive controller design method for a kind of cascade processes composed of several sub-processes is studied. This kind of cascade processcs has the characteristies of one-way connection. The process is divided into several two-input-two-output （TITO） sub-systems. The parameters of the first-order plus dead-time models for the transfer function matrices can be obtained using least squares method. Hence a distributed model predictive contn,ller is designed based on the coupling models of each sub-process. Simulation results on the temperature control of a reheating furnace are given to show the efficiency of the algorithm.     

基于BING-casDPM的快速行人检测算法

行人检测是计算机视觉技术中一个热门的研究热点,在汽车辅助驾驶和视频监控等方面具有重要作用.由于传统的可变形部件模型(deformable part model, DPM)采用滑动窗口检测方式,在背景区域花费大量检测时间会导致检测速度降低,因此提出了一种基于BING-casDPM的快速行人检测算法.首先基于二进制化梯度范数特征(binarized normed gradient, BING)训练一个二级支持向量机(support vector machine, SVM)分类器,通过该分类器快速标定出所测图像中包含各类物体的候选区域;然后根据候选区域窗口的特点进一步提取待检测框;最后将待检测框作为输入,使用级联DPM(cascade DPM, casDPM)模型进行精确检测,并将结果返回至原图.实验结果表明,该算法在基本不降低检测率的情况下,其检测速度比经典DPM模型检测速度提高了约16倍,比casDPM模型提高了约40%.     

Applications of cascade multilevel inverters

Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge‘s dc voltage is supported by its own de ca-pacitor. The new inverter can : ( 1 ) generate almost sinusoidal waveform voltage while only switching one timeper fundamental cycle ; (2) dispense with multi-pulse inverters‘ transformers used in conventional utility in-terfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical,simulated, and experimental results demonstrated the superiority of the new inverters.     

Multistage interband cascade photovoltaic devices with a bandgapof 0.23 eV operating above room temperature

Interband cascade （IC） photovoltaic （PV）device structures, consisting of multiple discrete InAs/GaSb superlattice absorbers sandwiched between electronand hole barriers, were grown by molecular beam epitaxy.Details of the molecular beam epitaxy growth and materialcharacterization of the structures are presented. The dis-crete absorber architecture enables certain advantages, suchas high open-circuit voltage, high collection efficiency,high operating temperature, and smooth integration ofcascade stages with different bandgaps. The two- andthree-stage ICPV devices presented in this article operate atroom temperature with substantial open-circuit voltages ata cutoff wavelength of 5.3 μm （corresponding to a bandgapof 0.23 eV）, the longest ever reported for room temperaturePV devices. The device characteristics indicate a high levelof current matching and demonstrate the advantages of theinterband cascade approach in thermophotovoltaic celldesign.