基于代理模型和NSGA-Ⅱ的超高强钢电阻点焊工艺参数多目标优化

为寻求超高强钢电阻点焊时最佳的焊接工艺参数,开展正交试验法设计三因素五水平的平板搭接点焊试验,以焊接时间、焊接电流和电极压力为可调的工艺参数,将熔核直径、压痕深度、拉剪强度及飞溅情况作为焊接接头质量评价指标.基于高斯过程回归和BP神经网络建立起焊接工艺参数与焊接接头质量评价指标之间关系的代理模型,训练的结果显示模型精度很高.最后利用带精英策略的非支配排序的遗传算法NSGA-Ⅱ实现多目标优化,得到各评价指标之间的最优pareto解集.经验证,各评价模型的相对误差值都很小.结果表明,该优化方法有较好的预测效果和稳定性.通过使用较少的试验数据,建立优化模型的方法对电阻点焊及其它焊接领域最佳焊接工艺参数的选取具有重要的指导价值.

Effect of high light and desiccation on photosystem Ⅱ in the seedlings and mature plants of tropical seagrass Enhalus acoroides during low tide

During low tide,the intertidal seagrass Enhalus acoroides is often exposed to high light and desiccation,which can seriously threaten its survival,at least partly by inhibiting photosystem Ⅱ(PSⅡ)activity.The response of leaves of E.acoroides to high light and desiccation was compared for seedlings and mature plants.Results show that the resistance of seedling and mature leaves to high light was quite similar,but to desiccation was very different.Seedling leaves were more sensitive to desiccation than the mature plant leaves,but had better water retention.The damage of desiccation to seedling leaves was mainly caused by dehydration,whereas that to mature plant leaves was caused by hypersaline toxicity.The recovery rate of PSⅡ of seedling leaves was significantly slower than that of the mature plants after the stresses disappeared,which may at least partly contribute to seedling mortality in the wild.In addition,compared to high light,desiccation seriously inhibited the recovery rate of PSⅡ activities even if the leaves became fully rehydrated to their normal relative water content(RWC)in the following re-immersion.Desiccation inhibited the recovery rate of RC/CS_(M)(reaction center per cross section(at t=t_(Fm)))to decrease the production of assimilatory power,which maybe the cause of the slower PSⅡ recovery in desiccation treatments.This study demonstrates that desiccation particularly coupling with high light have a very negative ef fect on the PSⅡ of E.acoroides during low tide and the sensitivity of seedlings and mature plants to desiccation is significantly different,which have important reference significance to choose an appropriate transplanting depth where seedlings and mature plants of E.acoroides not only receive sufficient light for growth,but also that minimize desiccation stress during low tide.

基于NSGA-Ⅱ算法的ACFM自由式旋转探头参数优化

交流电磁场检测(ACFM)方法是新型的无损检测方法,其中探头设计关乎检测的效率和信号处理的难度。基于此类问题,提出了自由式旋转单探头的设计,采用COMSOL Multiphysics软件对探头不同电磁参数进行仿真计算,得出适用的探头参数;此外根据旋转仿真分析得知,自由式旋转检测具有可行性且By磁场信号更具检测优势;同时基于旋转速度、平行检测速度、传感器相对位置以及检测范围的制约关系,采用非支配排序遗传算法Ⅱ(non-dominated sorting genetic algorithmⅡ,NSGA-Ⅱ)进行pareto求优,进而确定各参数,验证了旋转探头的高效率性。基于优化参数提出自由式旋转检测的信号处理模型,最后提出了旋转检测的系统搭建方法。

基于DE-INSGA-Ⅱ的联合循环系统性能及参数优化研究

为了研究联合循环系统长期运行后循环效率最优的热力参数匹配,提出了一种改进优化算法,该算法融合了非线性优化思想,并利用DE(differential evolution algorithm)算法思想改善种群初始分布,同时改进快速非支配排序遗传算法NSGA-Ⅱ(non-dominated sorting genetic algorithm)交叉算子。以底循环效率最大为目标函数结合约束条件,对系统的热力参数匹配进行多目标优化。仿真结果表明:所提的DE-INSGA-Ⅱ算法具有良好分布性和收敛性,搜索能力更强。在底循环效率优化问题上,较传统NSGA-Ⅱ算法提高0.44%,余热锅炉效率提高了0.86%,汽轮机效率提升了0.15%。该研究为联合循环机组运行的热力参数匹配提供了新的参考。

Orientation of Pigments in the Isolated PhotosystemⅡSub-core Reaction Center CP47/D1/D2/Cyt b-559 Complexes:A Linear Dichroism Study

Linear dichroism (LD) spectroscopy is an important technique in the study of the orientation and organization of pigments in the photosynthetic membrane complexes in vivo and in vitro . In this work, the orientation of the pigments in the isolated photosystem Ⅱ (PSⅡ) sub_core reaction center complexes was analyzed and characterized by means of low temperature absorption and LD spectroscopy. The preparations containing different amounts of CP47 isolated from spinach (Spinacia oleracea L.) chloroplast were used in order to investigate the orientation of pigments in the PSⅡ sub_core CP47/D1/D2/Cyt b_559 (CP47/D1/D2) complexes. Chlorophyll a (Chl a) absorbing at 680 nm in CP47/D1/D2/Cyt b_559 complex showed an orientation of the Q y transition parallel to the membrane plane. It is proposed that there are two forms of β_carotene (β_Car) in CP47/D1/D2/Cyt b_559 complex, denoted as β_Car (Ⅰ) and β_Car (Ⅱ), with different orientations, β_Car (Ⅰ) at 470 and 505 nm is roughly parallel to the membrane plane, and β_Car (Ⅱ) at 460 and 490 nm seems to be perpendicular orientation. Upon the photoinhibitory experiment β_Car (Ⅱ) was found to be photosensitive and easily photodamaged. It also showed that the positive LD signal observed at 680 nm was quite complicated. This signal is tentatively attributed to P680 and some Chl a of antenna in CP47 protein based upon our measurements.

Light-induced Damage of Photosystem ⅡPrimary Electron Donor P680: a High Performance Liquid Chromatographic Analysis of Pigment Content in D1/D2 /Cytochrome b559 Complex Under Photoinhibitory Conditions

ByHPLCanalyticalmethod ,thechangeofPSⅡRC’spigmentcontentintheprocessofphoto damageunderstrongilluminationfromspinach (SpinaciaoleraceaMill.)wascomparativelystudied .Theex perimentalresultsshowthat :(1)Inauthors’analyticalconditions ,(ofwhich ,[Chl]=150 μg/mL ,andthe illuminationstrengthwasputat 2 .3× 10 6 mJ·m- 2 ·s- 1) ,4 5minofilluminationcouldcausealmostthewhole lossofA6 80inthefourthderivativeabsorptionspectra ,whileA6 70decreasedtoaboutonehalfofitsoriginal intensity ;theabsorptionmaximuminred ,concurrently ,wasshiftedfrom 6 76nmto 6 71nm ,representingthe lossofmorethan 90 %ofthephotochemicalactivitiesofthePSⅡRC .(2 )Duringtheperiodofcontinuousil lumination ,theChlconcentrationdecreasedina 3_periodstyle ,whichmeantthatthefirst [Chl]decreasedto the 2 / 3ofitsoriginalamountfrom 2 0minto 4 0minafterilluminationhadstarted ,thenbecamestabilizedup toabout 6 0minofillumination ,thereafteraseconddecreaseof [Chl]inanotherabout2 0minuntilitreached about 30 %oftheoriginallevelandremainedunchangedfromabout 80minon .Theoriginalpigmentcompo nentsofD1/D2 /Cytb559wasapproximatelyas 6Chla∶2Pheo∶2 β_Carwhichareinsupportofauthors’pre viousproposalabouttheminimumChl/Pheoratioof 4∶2inPSⅡRC’spigmentcontents .(3)Afterabout 4 0 minofillumination ,anewlyappearedelutionpeakwasfoundbetweenthePheoandβ_CarpeaksinHPLCpro file ,attheretentiontimeof7.2min ,alittlelaterthanthat (6 .9min)ofPheomolecules ,thenewlyappeared elutionpeakwassupposedtobeakindofaccumulatedandstableproductofthePSⅡRC’sphotodamagepro cessandverymuchpossiblethePheo_likemolecules .

基于NSGA-Ⅱ算法的直流无刷电机控制方法

直流无刷电机是一种非线性、涉及多种变量以及强耦合的复杂系统,传统的基于线性控制的PI、PID控制器无法满足精确控制的要求.为提高控制性能,提出一种基于NSGA-Ⅱ优化PID参数控制直流无刷电机速度环的方法.NSGA-Ⅱ算法将速度超调量和ITAE法则相结合构造第一目标适应度函数;将速度调节时间和ITAE法则相结合,构造第二目标适应度函数.利用快速非支配排序和拥挤距离排序使种群个体收敛到最终的Pareto前沿,得到最优的PID参数.根据无刷直流电机的数学模型和运行特性搭建控制仿真模型,检验算法的控制效果,并与传统PI、PID算法的控制效果进行对比.结果表明:基于NSGA-Ⅱ算法优化PID参数的直流无刷电机控制具有较好的鲁棒性,响应速度快,几乎无超调量.

Comparison Between the Influences of Phosphatidylcholine and Triton X-100 on the Protein Secondary Structures and Oxygen-evolving Activity of Photosystem Ⅱ

The structural and functional alterations within the PSⅡ membrane from phosphatidylcholine reconstitution and Triton X_100 (TX_100) treatment were studied by using Fourier transform_infrared (FT_IR) spectroscopic technique and oxygen electrode. Phosphatidylcholine reconstitution showed no significant effect on the protein secondary structures of PSⅡ membrane but an increase of the rate of PSⅡ_mediated oxygen_evolution. The phosphatidylcholine lipids with different length of acyl chains displayed different capabilities to stimulate oxygen_evolution. In contrast, perturbation of the bilayer lipids by TX_100 resulted in obvious changes of the protein secondary structures within the PSⅡ membrane and in the loss of the PSⅡ_mediated oxygen_evolving activity. The results indicate the importance of membrane integrity in maintaining the stability of the photosynthetic membrane proteins.

Effects of CeCl_3 on Energy Transfer and Oxygen Evolution in Spinach Photosystem Ⅱ

Due to 4f electron characteristics and alternation valence, cerium involved in an oxidation-reduction reaction in plant, closely relating to photosynthesis. Our studies proved that cerium could promote photosynthesis and greatly improve spinach growth. However, the mechanism of promoting energy transfer and conversion by cerium remains unclear. Here we reported that the effects of Ce^3＋ on energy transfer and oxygen evolution in photosystem Ⅱ （PS Ⅱ ） isolated from spinach, which was related to 4f electron characteristics and alternation valence in Ce molecule. The methods of absorption spectrum, fluorescence spectrum were used in the research. Results showed that Ce^3＋ treatment at low concentration could suitably change PS Ⅱ mieroenvironment, increase the absorbance of visible light, improve the energy transfer among amino acids within PS Ⅱ protein-pigment complex, and accelerate energy transport from tyrosine residue to chlorophyll a. In summary, the photochemical activity of PS Ⅱ （fluorescence quantum yield） and its oxygen evolving rate were enhanced by Ce^3＋.

Effects of short-term low temperatures on photosystem Ⅱ function of samara and leaf of Siberian maple (Acer ginnala) and subsequent recovery

Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photosynthesis and effect of environmental stresses on its photosynthesis is still very limited. In the present study, responses of photosystem II (PSII) activity in samara and leaf of Siberian maple to short-term chilling/freezing and subsequent recovery potential were comparatively investigated by using polyphasic fluorescence test. The samara had more efficient photosynthesis (Fv/Fm and PIABS) and more efficient electron transport (φEo) but lower energy dis- sipation (DIo/RC) than leaf. Generally, the PSII performance and the electron transport for both samara and leaf were inhibited under low temperature stress, accompanied by an increase of energy dissipation in PSII reaction centers (RCs). PSII of both samara and leaf was not markedly affected by chilling and could acclimate to chilling stress. Short-term freezing could completely inhibit PSII activity in both samara and leaf, indicated by the drop of values of Fv/Fm, PIABS, φEo to zero. PSII functional parameters of short-term dark frozen samara could be largely recovered whereas those of frozen leaf could not be recovered. The higher tolerance of samara to short-term low temperature stress than leaf is of great ecological significance for seed development, population establishment of Siberian maple.

Effect of Nano-anatase TiO_2 on Spectral Characterization of PhotosystemⅡParticles from Spinach

The photosystem Ⅱ(PSⅡ) particles were purified by means of nano-anatase TiO_2 treatment of spinach and studied by spectroscopy. The results show that the electron transport and the oxygen-evolving rate of PSⅡ are accelerated after it has been treated with nano-anatase TiO_2; the UV-Vis absorption spectrum of PSⅡ particles is increased; the red shift of fluorescence emission peak of PSⅡ is 2 nm; the peak intensity is decreased; the PSⅡ signal Ⅱs of low temperature electron paramagnetic resonanace(EPR) spectrum is intensified under light, and the PSⅡ circular dichroism(CD) spectrum is similar to that of control. It is suggested that nano-anatase TiO_2 might bind to the PSⅡ reaction center complex and intensify the function of the PSⅡ electron donor, however, nano-anatase TiO_2 treatment does not change the configuration of the PSⅡ reaction center complex.

Optimization of Cutting Parameters for Trade-off Among Carbon Emissions, Surface Roughness, and Processing Time

As the manufacturing industry is facing increasingly serious environmental problems, because of which carbon tax policies are being implemented, choosing the optimum cutting parameters during the machining process is crucial for automobile panel dies in order to achieve synergistic minimization of the environment impact, product quality, and processing efficiency. This paper presents a processing task-based evaluation method to optimize the cutting parameters, considering the trade-off among carbon emissions, surface roughness, and processing time. Three objective models and their relationships with the cutting parameters were obtained through input–output, response surface, and theoretical analyses, respectively. Examples of cylindrical turning were applied to achieve a central composite design(CCD), and relative validation experiments were applied to evaluate the proposed method. The experiments were conducted on the CAK50135 di lathe cutting of AISI 1045 steel, and NSGA-Ⅱ was used to obtain the Pareto fronts of the three objectives. Based on the TOPSIS method, the Pareto solution set was ranked to find the optimal solution to evaluate and select the optimal cutting parameters. An S/N ratio analysis and contour plots were applied to analyze the influence of each decision variable on the optimization objective. Finally, the changing rules of a single factor for each objective were analyzed. The results demonstrate that the proposed method is effective in finding the trade-off among the three objectives and obtaining reasonable application ranges of the cutting parameters from Pareto fronts.

Blocking backward reaction on hydrogen evolution cocatalyst in a photosystem Ⅱ hybrid Z-scheme water splitting system

Photocatalytic Z-scheme water splitting is considered as a promising approach to produce solar hydrogen.However,the forward hydrogen production reaction is often impeded by backward reactions.In the present study,in a photosystem Ⅱ-integrated hybrid Z-scheme water splitting system,the backward hydrogen oxidation reaction was significantly suppressed by loading a PtCrOx cocatalyst on a ZrO2/TaON photocatalyst.Due to the weak chemisorption and activation of molecular hydrogen on PtCrOx,where Pt is stabilized in the oxidized forms,Pt^Ⅱ and Pt^Ⅳ,hydrogen oxidation is inhibited.However,it is remarkably well-catalyzed by the metallic Pt cocatalyst,thereby rapidly consuming the produced hydrogen.This work describes an approach to inhibit the backward reaction in the photosystem Ⅱ-integrated hybrid Z-scheme water splitting system using Fe(CN)6^3-/Fe(CN)6^4-redox couple as an electron shuttle.

Analysis of Chloroplast Ultrastructure,Photosystem Ⅱ Light Harvesting Complexes and Chlorophyll Synthesis in a Chlorophyll-Less Rice Mutant W2555

A comparative study on chloroplast ultrastructure and light harvesting complex of photosystem Ⅱ （LHC Ⅱ） was conducted between a new rice mutant （W2555） and its wild type （WT）. The chloroplasts of W2555 had less thylakoids and grana stacks compared with the wild type. There was no significant change in the composition of LHC Ⅱ polypeptide in W2555, while a decline had been noted in LHC Ⅱ content. Northern blot analysis with a specific cab gene probe showed no appreciable difference in the LHC Ⅱ mRNA level between the W2555and its wild type. The precursors of chlorophyll synthesis, 6-aminolevulinic acid （ALA） and porphobilinogen （PBG） were over accumulated in W2555, but the other precursors were all decreased. These results indicated that the decreased level of LHC Ⅱ in the mutant W2555 was attributed to the change of cab gene transcription, but a blockage in chlorophyll biosynthesis due to the formation of uroporphyrinogen Ⅲ （Urogen Ⅲ）.

基于超平面NSGA-Ⅱ的双输入双降压逆变器系统参数优化设计

针对第二代非支配排序遗传算法(NSGA-Ⅱ)计算过程中存在种群分布不均匀、收敛性速度较慢的问题,提出超平面NSGA-Ⅱ(HP-NSGA-Ⅱ).该算法通过连接反映种群边缘分布的极值点构造超平面,以其法向量为进化趋势,对临界层个体在超平面进行投影,促使种群朝着分布均匀且收敛良好的最优解进化.以双输入双降压型逆变器(DIDBI)为多目标优化对象,开关损耗、输出电压总谐波失真和滤波元件体积为优化目标,依据谐振频率、电感电流纹波和功率因数的要求,推导出滤波电容、滤波电感和开关频率的约束条件,比较分析HP-NSGA-Ⅱ与NSGA-Ⅱ、考虑各目标重要度的γ-NSGA-Ⅱ的应用场合和价值.以某型逆变器样机为例,开展参数优化设计实验研究,结果表明了设计的有效性与正确性.

Density and Ionization Parameters of Line and Continuum Emission from the Outer Regions of Accretion Disk in Active Galactic Nuclei

In this paper,the diffusion source model and the structure of magnetized accretion disk with self-gravity are used to study the density and the ionization parameter of the H_(Ⅱ) andH^(*)_(1) zone,of which most likely the broad line emitting region consists.Two different densities and ionization parameters are determined:the first<n(H_(Ⅱ))>andΞ(H_(Ⅱ)),corresponding to the mean density and ionization parameter in the completely ionized H_(Ⅱ) zone,and the second,<n(H*1)>andΞ(H^(*)_(1)),to the mean density and ionization parameters in the H^(*)_(1) zone.

Effects of Severe Drought and Glyphosate Stress on Physiological Characteristics and Protein Expression of Photosystem Ⅱ in Genentically Modified Soybean

[Objective] The paper was to investigate effects of glyphosate stress on physiological characteristics and protein expression of photosystem Ⅱ(PSⅡ) in genentically modified soybean GTS 40-3-2 seedlings under severe drought condition. [Method] A pot experiment was carried out in growth chamber to determine the response of genetically modified soybean treated by severe drought stress and different concentrations of glyphosate at the third compound leaf stage. [Result] Severe drought treatment increased the electrolyte leakage(EL), superoxide dismutase(SOD) and peroxidase(POD) activities, and decreased the relative water content(RWC), chlorophyll content, and catalase(CAT) activity. The EL, SOD and POD activities were significantly increased in severe drought and glyphosate treatments, which were related to glyphosate concentrations. The chlorophyll content decreased, which was also related to glyphosate concentrations. But the BWC and CAT activity were not affected by glyphosate concentrations. Western blot displayed that PSⅡ protein Lhcb2 was not affected by stress conditions and stably expressed. D1, D2 and Lhcb4 protein level decreased, and there was no significant change in Lhcb1 expression under severe drought stress. The protein levels of D1, D2, Lhcb1 and Lhcb4 decreased with the increase of glyphosate concentrations under severe drought and glyphosate stress. When the glyphosate concentrations were 0.92 and 1.84 kg·ai/hm^2, the protein levels of D1, D2 and Lhcb4 were slightly higher than those in severe drought stress. When the glyphosate concentrations were 3.68 and 7.36 kg·ai/hm^2, the protein level of D1, D2, Lhcb1 and Lhcb4 decreased sharply. [Conclusion] This research provides a theoretical basis for production of genetically modified soybean.

BAYESIAN PREDICTION FOR THE TWO-PARAMETER EXPONENTIAL DISTRIBUTION BASED ON TYPE Ⅱ DOUBLY CENSORING

The two-parameter exponential distribution is proposed to be an underlying model,and prediction bounds for future observations are obtained by using Bayesian approach.Prediction intervals are derived for unobserved lifetimes in one-sample prediction and two-sample prediction based on type Ⅱ doubly censored samples.A numerical example is given to illustrate the procedures,prediction intervals are investigated via Monte Carlo method,and the accuracy of prediction intervals is presented.

逐步Ⅱ型删失数据下逆威布尔分布的参数推断

逐步Ⅱ型删失方案在可靠性工程和生物医学中应用最为广泛,为此考虑在该删失方案下对寿命数据中常见的逆威布尔分布两参数进行推断。为解决对数似然函数过于复杂、求解较为困难的问题,利用EM算法进行参数估计,利用Bootstrap法进行区间估计。通过Monte Carlo模拟比较了不同删失模式下两参数的估计效果并通过实例分析展示了该估计方法的有效性。

QAD-Ⅱ型落筒机器人在自动络筒机上的应用

文章分别从QAD-Ⅱ型落筒机器人的运行参数、动作过程、安装基准、调试步骤及维护保养等五个方面进行分析研究,旨在自动络筒机上确认一套实用、可行的落筒机器人应用方案。该工艺方案的有序实施可有效提高国产络筒机自动化水平。