PID参数优化算法

PID参数优化是自动控制领域研究的一个重要问题。为了实现最优PID控制,PID参数优化算法已成为国内外控制理论研究的一个热点。随着计算机技术的发展,一些新的智能算法得到了迅速发展和广泛应用,并在理论和应用方面都有重要的意义。主要介绍了PID参数优化算法以及近年来在此方面取得的研究成果,并对未来PID参数优化的研究方向作了展望。     

气升式反应器的优化

从强化传质与节能方面概述了近年来国内外在气升式反应器结构参数优化、操作参数的优化及溶液性质等方面的研究工作 ,提出了今后的研究方向     

CLT/A 型旋风除尘器的多目标优化设计

本文应用多目标优化技术，对ＣＬＴ／Ａ型单筒旋风除尘器的结构参数进行了研究，建立了以除尘效率、压力损失为目标函数的旋风除尘器优化数学模型，并采用极小极大优化方法对其进行优化设计，给出了使其综合性能最佳的结构参数。     

基于遗传算法的油气混输管网参数优化设计

在地面油气混输管网优化的研究中,结构参数优化是极为重要的一个问题.本文对多目标非线性的规划问题,使用遗传算法对管网结构参数进行优化,提出了目标函数、水力及热力学模型.并得到了应用遗传算法的相关结论     

隔壁精馏塔结构参数优化研究

选择石化工业具有代表性的苯-甲苯-二甲苯体系为分离对象,以简捷和严格计算得到的隔壁精馏塔结构与操作参数为基础,以再沸器热负荷和年总费用为目标函数,采取"先分后合、等比优化"的方法,对隔壁精馏塔结构参数进行系统优化。研究表明:采用"先分后合、等比优化"方法优化隔壁精馏塔结构参数,较常见的单参数优化法更加合理。采用该法最终得到的优化方案与最初设计方案相比,隔壁精馏塔各段塔板数均不相同,操作参数不同,再沸器热负荷下降了81.39 kW,年总费用减少了2.0×10~4美元/a。结果表明,该方法可用于隔壁精馏塔结构参数的系统优化。     

含滞后及不确定参数动态过程系统的定量优化方法与应用

许多动态化工系统含有不确定参数。当含不确定参数的过程系统又带有滞后环节时,系统的优化问题就变得非常复杂。对含不确定参数的化工系统的动态过程进行优化,若未考虑滞后环节对动态优化结果的影响,不能保证系统实际操作的优化及安全运行。本文采用改进的有限元正交配置优化算法,较好地解决了含有滞后、不确定参数的化工过程的动态优化问题。最后将一个具有循环返料的反应-分离器系统以及一个绝热反应釜作为案例对该优化方法的应用进行分析,根据案例的研究验证了该优化方法的有效性,从而为含有滞后、不确定参数的动态系统的设计和操作性能优化提供一种有效的定量分析方法和理论依据。     

注射成型工艺自适应优化技术研究进展

综述了注射成型工艺自适应优化技术的研究现状，从聚合物熔体物性参数（黏度、比容）和熔体质量参数变化的分析与定量表征，以及注射成型工艺自适应优化三方面详细介绍了国内外学者在注射成型工艺自适应优化技术方向的研究进展，最后对现存的问题进行了归纳总结，并对未来的研究方向进行了展望。     

铆接过程的优化和分析

几十年来铆接技术被用于薄板零件之间的紧固。近几年研究的重点大多放在连接参数和连接质量的完善,而板材连接的研究却很少见。因此,本文着重建立快而简便的铆接优化过程。过程从大体上分析铆接技术的主要参数开始。这些主要参数选自材料特性、几何参量和加工参数。通过专题研究得到了这些参数的分类。此后采用优化方法来评定这些参数对于连接质量的影响。随着优化目标的合理定义,每个参量的重要性能运用于设计阶段。最后,优化参数配置得到公认并展示过程的可行性。     

基于响应面法的汽车轮眉注塑工艺优化

以汽车轮眉为研究对象,选取模具温度、熔体温度、保压压力以及保压时间4个工艺参数作为实验变量,以轮眉的最小翘曲变形作为优化目标,基于响应面法的中心复合设计方法,结合CAE仿真模拟技术,建立了轮眉翘曲变形同工艺参数之间的响应模型,通过方差分析研究了工艺参数及其交互作用对优化目标的影响。通过软件优化确定了最优工艺参数组合,实验结果表明最大翘曲变形量从6.311 mm降至3.367 mm。     

炭阳极焙烧工艺参数多目标决策

研究将多目标模糊决策方法应用到炭阳极焙烧工艺参数优化中,通过分析焙烧过程中工艺参数与质量参数的相关性,以焙烧工艺参数为决策论域,炭阳极的质量参数为指标函数决策得到最优焙烧工艺参数,优化了焙烧曲线。该方法为提高炭阳极生产质量,实现炭阳极焙烧过程中的降耗、节能及减排等方面的优化控制创造条件。     

MODELING DISSOLVED OXYGEN CONCENTRATION FOR OPTIMIZING AERATION SYSTEMS AND REDUCING OXYGEN CONSUMPTION IN ACTIVATED SLUDGE PROCESSES: A REVIEW

Aeration accounts for 30% to 75% of the total energy consumption in activated sludge processes (ASPs). This percentage can be significantly reduced since most aeration systems are not optimized for unsteady influent flow rates and oxygen requirements. Reconfiguration, replacement, and the application of optimal dissolved oxygen (DO) control strategies for current aeration systems within the facility and model-based optimization of DO in wastewater treatment plants can lead to impressive increased energy efficiency and savings and improved stability of the system. These measures increase the operational lifetime of the aeration equipment and improve effluent and activated sludge quality. This article provides a review of two critical nonlinear time-varying parameters that characterize the DO concentration dynamics in an ASP: the oxygen uptake rate (OUR), related to microorganism activity, and the volumetric oxygen mass transfer function, represented by the oxygen transfer rate (OTR). Second, the physico-chemical, geometric, and dynamic factors and aerator type affecting the oxygen mass transfer coefficient (K _L a) are thoroughly discussed. The article concludes with model-based optimization, explaining the usefulness of accurate DO models in wastewater treatment, and provides examples for plant-wide or water chain cycle–focused optimizations.     

Helicoverpa zea CYP6B8 and CYP321A1: different molecular solutions to the problem of metabolizing plant toxins and insecticides

Under continual exposure to naturally occurring plant toxins and synthetic insecticides, insects have evolved cytochrome P450 monooxygenases (P450s) capable of metabolizing a wide range of structurally different compounds. Two such P450s, CYP6B8 and CYP321A1, expressed in Helicoverpa zea (a lepidopteran) in response to plant allelochemicals and plant signaling molecules metabolize these compounds with varying efficiencies. While sequence alignments of these proteins indicate highly divergent substrate recognition sites (SRSs), homology models developed for them indicate that the two active site cavities have essentially the same volume with distinct shapes dictated by side-chain differences in SRS1 and SRS5. CYP6B8 has a narrower active site cavity extending from substrate access channel pw2a with a very narrow access to the ferryl oxygen atom. This predicted shape suggests that bulkier molecules bind further from the ferryl oxygen at positions that are not as effectively metabolized. In contrast, CYP321A1 is predicted to have a more spacious cavity allowing larger molecules to access the heme-bound oxygen. The metabolic profiles for several plant toxins (xanthotoxin, angelicin) and insecticides (cypermethrin, aldrin and diazinon) correlate well with these predictive models. The absence of Thr in the I helix of CYP321A1 and hydroxyl groups on many of its substrates suggests that this insect P450 mediates oxygen activation by a mechanism different from that employed by CYP107A1 and CYP158A1, which are two bacterial P450s also lacking Thr in their I helix, and most other P450s that contain Thr in their I helix.     

Scouting around 1,2,3,4-Tetrahydrochromeno[3,2-c]pyridin-10-ones for Single- and Multitarget Ligands Directed towards Relevant Alzheimer's Targets

A number of 1,2,3,4-tetrahydrochromeno[3,2-c]pyridin-10-one derivatives have been synthesized and screened against different targets involved in the onset and progression of Alzheimer's disease (AD), such as acetyl- and butyrylcholinesterase (AChE and BChE), monoamine oxidases A and B (MAO A and B), aggregation of β-amyloid (Aβ) and reactive oxygen species (ROS) production. Derivatives 1 c , 3 b , 4 and 5 a showed multifaceted profiles of promising anti-AD features and returned well-balanced multitargeting inhibitory activities. Moreover, compound 1 f , a potent and selective human MAO B inhibitor (IC₅₀=0.89 μM), proved to be a safe neuroprotectant in a human neuroblastoma cell line (SH-SY5Y) by improving viability impaired by Aβ_1–42 and pro-oxidant insult. Furthermore, structure–activity relationships (SARs) and docking models were derived in order to assist further hit-to-lead optimization stage.     

Aliphatic poly(alkylene dithiocarbonate)s: Thermal properties and structural characteristics of poly(hexamethylene dithiocarbonate)

Aliphatic poly(alkylene dithiocarbonate)s are an interesting class of potentially biodegradable and biocompatible materials in analogy with their homologous poly(alkylene carbonate)s. In this paper, the properties of poly(hexamethylene dithiocarbonate) (SSR6) are compared to those of poly(hexamethylene carbonate) (HMC) in order to study the effect of the substitution of oxygen atoms with sulphur atoms in the polymer backbone. SSR6 presents a higher level of crystallinity and a faster crystallisation rate with respect to HMC. The melting temperature in SSR6 is about 60 °C higher, due to a solid-solid transition between phase I, stable at room temperature, and phase II, present at high temperature. HMC crystallises only in phase I and melts at a relatively low temperature (30 °C). The capacity of SSR6 to crystallise in phase II has been attributed to the higher flexibility and mobility of the chains containing -S-CO-S- groups with respect to the chains containing -O-CO-O- groups. The pure phase II in SSR6 has been obtained in isothermal conditions and its crystallisation rate and mechanism have been analysed.     

Synthesis, morphology and photophysics of novel hybrid organic-inorganic polyhedral oligomeric silsesquioxane-tethered poly(fluorenyleneethynylene)s

A series of novel hybrid organic-inorganic light-emitting materials, polyhedral oligomeric silsesquioxane-tethered poly(fluorenyleneethynylene)s, were successfully synthesized via Sonagashira coupling reaction. The chemical structures of these copolymers were determined by ¹H NMR and FT-IR spectra. The morphologies of these copolymers were studied in details using TEM and WAXD. The WAXD data showed that POSS formed aggregation instead of crystallization in the polymer matrix, indicating the significant effect of the backbone constraint on POSS crystallization. Furthermore, it also revealed that the interchain interaction weakened and the interchain distance increased after introducing POSS groups. The TEM data indicated that POSS aggregates were well dispersed in polymer matrix. In accordance with the morphological investigation, the results of UV-vis absorption and photoluminescence emission spectra of these copolymers showed that the tendency toward planar conformation of conjugated backbones reduced to a certain extent due to weakened interchain interaction. Accordingly, these copolymers exhibited the enhanced quantum yields in the solid state. In addition, owing to the thermal and oxygen stability of hybrid POSS, the thermal spectral stability of these polymers was also improved greatly.     

Synthesis and properties of <Emphasis Type="Italic">ortho</Emphasis>-linked aromatic poly(ester-amide)s and poly(ester-imide)s bearing 2,3-bis(benzoyloxy)naphthalene units

Two new naphthalene-ring-containing bis(ester-amine)s, 2,3-bis(4-aminobenzoyloxy)naphthalene (p-2) and 2,3-bis(3-aminobenzoyloxy)naphthalene (m-2), were prepared from the condensation of 2,3-dihydroxynaphthalene with 4-nitrobenzoyl chloride and 3-nitrobenzoyl chloride, respectively, followed by catalytic hydrogenation. The novel aromatic poly(ester-amide)s and poly(ester-imide)s having 2,3-linked bis(benzoyloxy)naphthalene units have been synthesized from the polycondensation reactions of bis(ester-amine)s (p-2 and m-2) or an equimolar mixture of 4,4′-oxydianiline and p-2 or m-2 with various aromatic dicarboxylic acids and dianhydrides. The synthesis of the poly(ester-amide)s was achieved by the phosphorylation polyamidation reaction by means of triphenyl phosphate, and the synthesis of the poly(ester-imide)s included ring-opening polyaddition to give poly(amic acid)s followed by chemical imidization to polyimides. Most of the poly(ester-amide)s were readily soluble in various organic solvents. Six poly(ester-amide)s and two poly(ester-imide)s derived from less rigid diacids and dianhydrides, respectively, were amorphous and could be solution-cast into transparent and tough films with good mechanical properties. Most of the poly(ester-amide)s displayed discernible glass-transition temperatures (T _gs) between 192 and 223 °C in the DSC traces. All of the poly(ester-imide)s, except for one sample, showed clear T _g values between 225 and 265 °C by DSC. These poly(ester-imide)s showed excellent thermal stability with 10 wt% loss temperatures above 460 °C in nitrogen or air.     

The effects of a biosurfactant on oxygen transfer in a cyclone column reactor

A laboratory-scale cyclone column reactor was tested to determine how its oxygen transfer characteristics were affected by surfactants in the liquid medium. The volumetric oxygen transfer coefficient was greatly decreased by small quantities of the synthetic surfactants dodecyltrimethylammonium bromide and sodium dodecylsulfate, and the biosurfactant surfactin produced by Bacillus subtilis (ATCC 21332). Since the gas holdup fraction was generally increased due to foaming, the effectiveness of the surfactants was probably due to an increase in the interfacial film resistance. B. subtilis was grown in the cyclone column to 0.6 g dm^?3 with a significant level of surfactin produced while maintaining at least 75% oxygen saturation in the broth. Process optimization and scale-up of surfactin production will have to consider oxygen transfer as a key parameter.     

Macrocycles 25. Cyclic poly(ether sulfone)s derived from 4-tert-butylcatechol

Poly(ether sulfone)s were prepared by polycondensation of silylated 4-tert-butylcatechol and 4,4′-difluorodiphenylsulfone in N-methylpyrrolidone. The feed ratio and the reaction time were varied to study the influence of stoichiometry and conversion on molecular weight and extent of cyclization. Molecular weights and molecular weight distributions (MWD)s were characterized by SEC measurements calibrated with polystyrene. Light scattering confirmed that calibration with polystyrene gives reasonable results and revealed a tendency towards a bimodal MWD for the samples rich in cycles. The MALDI-TOF mass spectrometry indicated that the extent of cyclization increased with higher conversion and with optimization of the stoichiometry. This interpretation was confirmed by ¹H NMR endgroup analyses. For the samples with the highest molar masses only mass peaks of cycles were found, which were detectable up to 20 000 Da before and up to 27 000 Da after fractionation. Via the pseudo-high dilution method low molar mass poly(ether sulfone) containing more than 95 mol% of cycles were prepared, and even these low molar mass samples had broad MWDs. DSC measurements indicated that the glass transition temperatures depend on the structure of the endgroups and increase with higher fractions of cycles.     

Polymers with triphenylamine units: Photonic and electroactive materials

Organic hole-transporting materials are intensively investigated as thin-layer electro-optical devices, including organic light-emitting diodes, solar cells, organic field-effect transistors and photo-refractive holographic materials. In this review, we discuss synthetic routes and optical (UV-vis, PL, CV) and electrical (I-V, EL, hole drift mobility) properties of polymers with triphenylamine (TPA) units in the main chain or as pendant groups, such as poly(vinylene)s, poly(amide)s, poly(imide)s, poly(azomethine)s, poly(arylate)s, poly(urethane)s and poly(ester)s. The introduction of vinyl, acetylene, ester, imide, amide or azomethine moieties in TPA leads to new functional materials based on their synergistic effects. The introduction of bulky triphenylamine in macromolecules tends to suppress intermolecular aggregation, reduce the crystallisation propensity and improve the hole-transporting ability of the materials.     

直拉法单晶硅制备过程控氧技术研究进展

随着我国光伏行业的快速发展,直拉(CZ)法制备的单晶硅朝着大尺寸、高品质、低成本的方向发展,然而随着单晶硅尺寸越来越大,其内部氧杂质含量偏高的问题也越来越突出。本文在介绍CZ法制备单晶硅过程中氧杂质传输机理的基础上,归纳总结了单晶硅生产过程的控氧技术现状,分析了热场结构优化、工艺优化、掺杂元素、氩气流场优化以及新型CZ技术对单晶硅氧杂质含量的影响规律,并对控氧技术的发展方向提出了展望。