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1.
针对目前大功率运输车辆在起步阶段车轮容易出现打滑空转现象,提出了基于最优滑转率的驱动防滑控制策略,将驱动防滑控制系统应用到重载运输车辆上。通过监测车辆行驶滑转率,由模糊控制系统控制电机调整转矩,将轮胎的滑转率控制在最优滑转率附近。在Matlab/Simulink建立仿真模型,并进行一系列在不同路面工况下的仿真试验。结果表明模糊控制能够有效控制滑转率,能够将滑转率稳定控制在0.2左右,并且提高利用附着系数,使其接近路面自身的附着系数。在低附路面仿真结果中,将车身加速度从0.8提高到了0.95 m/s2左右,并使其稳定在0.95 m/s2,达到了提高车辆的动力性的目的。最后,依据工业级的嵌入式系统Compact RIO-9024和PXI8110搭建了硬件在环仿真系统。通过对该系统的硬件在环仿真研究,整车在不同路面上的响应时间小于1 s,能够满足实车行驶时的实时性要求,验证了模糊控制算法的实时性。该研究可为大型工程运输车辆的驱动防滑设计提供参考。 相似文献
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针对设施园艺特殊作业场景对电驱移动平台灵活作业与高操纵稳定性需求,该研究设计了一种四轮轮毂电机独立驱动的分布式设施园艺电驱移动平台,并提出了一种可提高转向灵活性与稳定性的自适应防滑控制策略。在该控制策略中,首先构建电驱移动平台动力学模型与Ackermann差速转向模型,结合速度瞬心原理及轮胎侧偏角确定各车轮转向目标转速;其次,为提高电驱移动平台对时变附着系数的适应能力,采用改进的强跟踪自适应无迹卡尔曼滤波算法设计复杂路面识别器,实现对路面附着系数准确估计;最后,设计基于自适应滑模算法的防滑控制器,根据路面附着系数估计值确定车轮相对最佳滑转率并实时控制滑转率。为验证所提控制策略的有效性,开展了Carsim-MATLAB/Simulink联合仿真与分布式设施园艺电驱移动平台实车试验。试验结果表明,所提控制策略可准确估计复杂道路下路面附着系数,降低车轮滑转率误差;在不变路面、对接路面与对开路面3种工况下,左侧车轮滑转率误差分别为0.031、0.015和0.038,右侧车轮滑转率误差分别为0.026、0.005和0.028;在不变路边随机路面实测路况下,电驱移动平台路面附着系分别数约为0.44和0.47,最大滑转率分别约为0.69和0.68,有效抑制了轮胎转向时的过度滑转,提高了电驱移动平台的行驶稳定性。研究可为设施园艺车辆驱动防滑控制提供具体理论依据和实施方案。 相似文献
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针对电动拖拉机整机控制中与驱动转矩相关且通用性较强的功能环节,在驱动系统上层搭建了一种通用型的驱动转矩管理控制模型。以满足田间作业需求、提升作业质量为目标,将输入信号标定为期望作业车速,并进一步转化为电机目标转速。根据实际转速与目标转速的偏差,计算电机目标输出转矩,以使电机需求功率与作业负载相平衡。进一步考虑巡航作业过程中驱动转矩变化引起的整机冲击度、当前转速下电机可用最大转矩以及驱动系统过温、电池放电欠压的影响,依次搭建了针对目标输出转矩的斜坡限制、基于转速的转矩容量限制和极端工况下的比例减载限制模型。搭建了包括电池、驱动电机以及整机纵向动力学在内的电动拖拉机模型。基于驱动转矩管理模型设计了目标控制器,并搭建了dSPACE硬件在环测试平台,分别对转矩管理模型中的各个参数进行了标定,并对牵引作业工况下驱动系统的输出特性进行了测试,结果表明:在牵引作业时,实际车速可平稳跟踪期望作业车速,跟踪误差主要取决于驱动轮的滑转程度,当期望车速改变时,实际车速按标定斜率向期望值平缓过渡;作业过程中,模型输出转矩始终处于电机转矩容量范围以内,且转矩变化率不超过35N·m/s,与未经斜坡限制处理的原始目标转矩相比,转矩变化趋于缓和;当电池输出电压低于欠压报警阈值时,驱动转矩管理模型根据电池欠压程度将模型输出转矩比例缩减10%～27%,确保电池输出电压不低于停机阈值。所搭建的驱动转矩管理模型可为电动拖拉机整机控制器的设计提供技术参考。 相似文献
4.
插电式四驱混合动力汽车能量管理与转矩协调控制策略 总被引：4，自引：2，他引：2
为克服传统比例-积分-微分(proportion integration differentiation,PID)以及模糊逻辑算法的缺陷、保障汽车经济性并改善乘员的乘坐舒适性,该文采用自适应模糊PID算法,建立了驾驶员模型。使用基于发动机输出转矩最优的能量管理控制策略,简述了驱动模式判别条件及转矩分配方法。提出1种"发动机调速+离合器模糊PID控制+发动机动态转矩查表+双电机转矩补偿控制"转矩协调控制方法,简述了模式切换步骤。在dSPACE实时仿真系统上对控制策略进行了硬件在环仿真。仿真结果表明,该控制策略在能量管理方面控制效果良好,动力部件的输出与控制策略完全吻合且平均车速误差下降37.1%。引入转矩协调之后,整车最大冲击度下降47.5%。该文的研究方法可以为制定复杂混合动力系统的控制策略提供参考。 相似文献
5.
路面不平度对车辆制动过程中轮胎动态性能影响的仿真分析 总被引：5，自引：0，他引：5
采用作者建立的非线性时变轮胎模型,仿真分析了路面不平度幅值及路面空间频率变化对地面附着性能的影响。得出路面不平度增大时,使路面对车轮的附着能力下降,因而使制动距离增长的结论。同时说明非线性时变轮胎模型能较真实地体现路面不平度的影响,对不平路面上车辆制动性能仿真是一个有效的轮胎力学模型 相似文献
6.
电动轮式移动小车控制系统设计与试验 总被引：2，自引：6，他引：2
为了实现电动轮式移动小车能在实际不同的负载和路况下可以稳定的运行工作,该文研制了小车的四轮独立驱动的电机驱动和四轮转向控制系统,该系统由主控制芯片STM32F103RCT6对移动小车进行解算得出4个驱动轮的速度,然后对每个驱动电机进行转矩分配,控制4台用于驱动的无刷直流轮毂电机、2台转向直流电机以及2台制动用直流电机,使得小车实现直线行驶、转向和原地转向;通过单片机ATMEGA48PA控制4台无刷直流轮毂电机换相;采用驱动芯片IR2113驱动场效应管FQA140N10,并利用电机内部霍尔传感器输出的脉冲信号检测无刷直流电机的速度,采用放大器LM358搭建过载保护电路。试验结果表明,所开发的小车驱动控制系统实现了四轮电子差速与转矩分配,移动小车能在水泥路面、干泥土路面、斜坡和草地上稳定可靠运行,小车限速20 km/h,爬坡度为8°。在空载情况下能匀速运行8~10 h,带额定负载250 kg情况下能匀速运行4~5 h,有较好的负载性能,满足农业运输及农田作业的需求,减轻人的体力劳动,提高生产效率。该研究可为应用于田间作业的电动移动小车的机械设计及电气控制系统设计提供参考。 相似文献
7.
车辆自适应悬架控制方法的研究 总被引：1，自引：0，他引：1
对车辆悬架提出了一种Ｇａｉｎ Ｓｃｈｅｄｕｌｉｎｇ（ＧＳ）自适应控制方法。控制器的设计仍采用最优控制理论,但控制增益可变,以自适应于路面输入条件的变化。主要对路面输入变化的估计时间和用以决定控制增益变化的系统输出信号的选择进行了研究。仿真结果表明,只要事先路面输入变化范围能够被合理地估计,ＧＳ控制是一个可行的方法,并可进一步提高车辆的行驶性能。 相似文献
8.
基于V2X的混合动力汽车分层能量管理及优化 总被引：1，自引：1，他引：0
为了解决混合动力汽车的实时能量管理及优化问题,在保证不过多简化被控对象的基础上得到最优解,该文提出一种基于V2X（vehicle to vehicle,车车通信,以及vehicle to infrastructure,车与交通设施通信）的分层控制方法。设计了一种分层控制器,上层控制器基于交通信号灯正时（signal phase and timing,SPAT）得到目标车速的初始值,并采用多岛遗传算法和非线性模型预测得到最优目标车速。下层控制器根据上层控制器的最优目标车速,采用自适应等效燃油消耗最小原理（adaptive equivalent consumption minimization strategy,A-ECMS）,得到发动机和电机的最优输出功率。该文对分层控制方法进行了硬件在环仿真,仿真结果表明,该文提出的分层控制方法可以很好地实现混合动力汽车的实时能量管理,有效地避免混合动力汽车红灯停车,实现良好的车速跟随并减少百公里油耗。该研究可为解决混动力汽车实时能量管理及优化提供参考。 相似文献
9.
电传动车辆中轮边驱动电机壳体振动直接作用于悬架下端,为评价电机激振力对悬架系统的输出影响,在考虑电机—路面不平度耦合激励影响下构建系统运动微分方程组进行分析。应用气体状态方程和油液孔口出流方程建立了单气室油气悬架非线性数学模型,采用麦克斯韦应力法对异步电机竖直方向激振力进行求解,采用白噪声滤波法模拟时域内随机路面,将耦合激励信号作用于系统模型,将悬架输出力和电机激振力带入系统运动方程组联立求得数值解,改变参数可进行多工况下平顺性仿真,并通过实车试验与耦合振动模型进行了对比。结果表明在常见正弦路面激励下,在考虑电机激振影响下系统输出振幅约增大10%且达到稳定所需时间更长。高频激振力使系统加速度功率谱幅值变大,在激振力自身频率段影响明显,不可忽略。通过分析实测数据与仿真数据,验证了耦合激励模型在实车中的有效性;耦合激励模型对电动车悬架及整车平顺设计有指导意义。 相似文献
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11.
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。 相似文献
12.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing. 相似文献
13.
《中国生态农业学报》2014,(8)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
14.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils. 相似文献
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Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
Abstract A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species. 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L?1 nitric acid (HNO3) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L?1 ammonium acetate (NH4OAc) and 1.0 mol L?1 HNO3 extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils. 相似文献
17.
Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater 总被引：3，自引：0，他引：3
Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells. 相似文献
18.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions. 相似文献
19.
Y. Bashan J. J. Bustillos L. A. Leyva J.-P. Hernandez M. Bacilio 《Biology and Fertility of Soils》2006,42(4):279-285
Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several
photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene.
This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments
for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference
in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless
of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots.
Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production
or the positive response of the plants towards A. brasilense Cd inoculation. 相似文献
20.
Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico
and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria
(Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite
amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation.
Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured
as transpiration and diffusive resistance, when these trees were cultivated without water restrictions. 相似文献