Tuning of an optimal fuzzy PID controller with stochastic algorithms for networked control systems with random time delay

An optimal PID and an optimal fuzzy PID have been tuned by minimizing the Integral of Time multiplied Absolute Error (ITAE) and squared controller output for a networked control system (NCS). The tuning is attempted for a higher order and a time delay system using two stochastic algorithms viz. the Genetic Algorithm (GA) and two variants of Particle Swarm Optimization (PSO) and the closed loop performances are compared. The paper shows that random variation in network delay can be handled efficiently with fuzzy logic based PID controllers over conventional PID controllers.     

基于专家系统的跳汰机自动排料系统的实现

介绍了PLC在跳汰机自动排料系统中的应用并引入了模糊控制概念,详述了排料系统的基本控制原理及构成.并对PLC进行编程,通过PLC输出口的数据对此机构进行控制.     

Fully integrated InGaAs/InP single-photon detector module with gigahertz sine wave gating

InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of GHz clock rates are crucial components for the high-speed quantum key distribution (QKD). We have developed for the first time a compact, stable, and user-friendly tabletop InGaAs/InP single-photon detector system operating at a 1.25 GHz gate rate that fully integrates functions for controlling and optimizing SPAD performance. We characterize the key parameters of the detector system and test the long-term stability of the system for continuous operation of 75 h. The detector system can substantially enhance QKD performance and our present work paves the way for practical high-speed QKD applications.     

Construction of molecule-selective mixed matrix membranes with confined mass transfer structure

Extraordinary mass transfer phenomenon is usually found when the small molecules pass through a confined structure, whose effective size is commensurate with the mean free path of the molecules. Small changes in the confined mass transfer structure (including size, morphology and properties) will lead to significant fluctuations of the mass transfer coefficient. The mass transfer of the penetrant molecules in the dense membranes for pervaporation, gas separation and so on, is located in the scope of confined mass transfer. Incorporating nanofillers into polymer matrix to construct mixed matrix membranes (MMMs) is an effective approach to tune the confined mass transfer structure and enhance the performance of the widely used polymeric membranes. This reviewfocuses on the construction andmanipulation of the confined structure in the polymeric membranes via incorporating one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) fillers.The comparison of the MMMs for pervaporation is summarized, and the research prospective of the MMMs is provided.     

Modeling and simulation of enhancement mode p-GaN Gate AlGaN/GaN HEMT for RF circuit switch applications

An enhancement mode p-GaN gate AlGaN/GaN HEMT is proposed and a physics based virtual source charge model with Landauer approach for electron transport has been developed using Verilog-A and simulated using Cadence Spectre, in order to predict device characteristics such as threshold voltage, drain current and gate capacitance. The drain current model incorporates important physical effects such as velocity saturation, short channel effects like DIBL (drain induced barrier lowering), channel length modulation (CLM), and mobility degradation due to self-heating. The predicted I_d-V_ds, I_d-V_gs, and C-V characteristics show an excellent agreement with the experimental data for both drain current and capacitance which validate the model. The developed model was then utilized to design and simulate a single-pole single-throw (SPST) RF switch.     

Manipulation of morphology and structure of the top of GaAs nanowires grown by molecular-beam epitaxy

Self-catalyzed GaAs nanowires (NWs) are grown on Si (111) substrates by molecular-beam epitaxy. The effect of different closing sequences of the Ga and As cell shutters on the morphology and structural phase of GaAs NWs is investigated. For the sequences of closing the Ga and As cell shutters simultaneously or closing the As cell shutter 1 min after closing the Ga cell shutter, the NWs grow vertically to the substrate surface. In contrast, when the As cell shutter is closed first, maintaining the Ga flux is found to be critical for the following growth of GaAs NWs, which can change the growth direction from[111] to <111>. The evolution of the morphology and structural phase transition at the tips of these GaAs NWs confirm that the triple-phase-line shift mode is at work even for the growth with different cell shutter closing sequences. Our work will provide new insights for better understanding of the growth mechanism and realizing of the morphology and structure control of the GaAs NWs.     

Coagulation dynamics of fractal flocs induced by enmeshment and electrostatic patch mechanisms

The size and structure of flocs during floc formation were monitored for various coagulation mechanisms. Two distinctive mechanisms, namely, enmeshment and electrostatic patch, govern the dynamics of kaolin particles coagulation by polyaluminum chloride (PACl). They were investigated by small angle static light scattering (SASLS) and solid-state ²⁷Al NMR. In addition, a novel wet SEM (WSEM) was used in-situ to image the morphology of the aggregate in aqueous solution. Synthetic suspended particles were coagulated by two PACl products, a commercial product (PACl) and one laboratory product (PACl-E). The PACl-E contained more than 60% Al₁₃ while the PACl contained only 7% Al₁₃, with large percentage of colloidal Al. For coagulation by PACl at neutral pH and high dosage where the strong repulsion between particles occurs, the enmeshment ruled by reaction-limited aggregation (RLA) results in larger sweep flocs as well as higher fractal dimensional structure. For coagulation by PACl-E at alkaline pH and low dosage, the flocs were coagulated predominately by electrostatic patch with Al₁₃ aggregates. At such condition, it is likely that diffusion-limited aggregation (DLA) predominately rule PACl-E coagulation. The fractal dimension (D_s) values of PACl and PACl-E flocs formed at enmeshment and electrostatic patch increased with dosage, respectively. When breakage of flocs occurs, the breakage rate of PACl-E flocs is slower than that of sweep flocs. By WSEM imaging, the adsorption of spherical Al precipitates onto the particles was observed to form sweep flocs with a rough and ragged contour, while the PACl-E flocs were formed with a smooth and glossy structure.     

钼化合物对水泥熟料形成的影响

<正> 1 引言 减少能耗和提高熟料质量是发展水泥技术的两个主要目标。为了提高产量和质量并节约能源,通过使用矿化剂来降低熟料工艺中的煅烧温度的技术已受到国内外的广泛关注。 1992年,作者在关于利用钼铁合金矿的尾矿中的微量元素来生产波特兰水泥的研究中发现:用作矿化剂的钼化合物会由于其类型的不同而对熟料形成产生不同的影响。有关矿化剂的报导较多,但是少有报导涉及到把钼铁合金矿的尾矿作为矿化剂使用。与石膏-荧石矿     

Increasing the dissolution rate of a low-solubility drug through a crystalline-amorphous transition: a case study with indomethacin [correction of indomethicin

The purpose of this research is to further the understanding of the crystalline to amorphous phase transition (amorphization) that occurs when some crystalline drugs are dry blended with porous adsorbents. Indomethacin (IMC) and three grades of silica gel (SGs) were used in the study. Amorphization of crystalline IMC occurs rapidly during dry mixing with SG and was independent of mixing intensity and time. Extent of amorphization increases with lower ratios of IMC:SG and with decreased IMC and SG particle size. Blocking H-bonding silanol groups on SG by chemical modification reduced the extent of amorphization. IMC-SG mixtures showed improved dissolution rates over crystalline IMC, the improvement being directly related to the extent of amorphization. To preserve the improved dissolution rate, mixtures should be protected from moisture and heat. This approach holds promise as a mean of improving the dissolution rate of sparingly soluble drugs such as IMC.     

Tuning the morphologies of SiC nanowires via the control of growth temperature, and their photoluminescence properties

Single crystalline SiC nanowires were synthesized by a catalyst free vapor deposition method using elemental silicon and graphite carbon as the starting materials. The phase, morphology, crystal structure, and defects of the products were characterized by x-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Within a 6?h reaction time, the morphology of the SiC nanowires can be tuned to cylinder, hexagonal prism, or bamboo shape by simply altering the reaction temperature from 1470?°C, 1550?°C to 1630?°C, respectively. The photoluminescence of these differently shaped SiC nanowires was measured and is discussed. Based on the characterization results, the vapor-solid growth mechanisms for the multi-shaped SiC nanowires are proposed by taking into account the possible reactions between intermediate gas phases, the reaction steps, and the surface energy minimization.