狭闭空间内苗盘物流化搬运机器人运动规划与试验

针对植物工厂狭小密闭工作空间(狭闭空间)内大范围作业需求,提出了一种应用于植物工厂内部的物流化搬运机器人。采用D-H法建立连杆坐标系,通过求解运动学正解对机器人运动空间进行分析,在此基础上,采用边界追踪法规划了一种满足植物工厂立体式培育特点的滑切式搬运最优轨迹,提取轨迹上若干点,求解提取点运动学逆解,采用三次样条插值拟合机械手臂关节变量随时间变化函数,并在实验室中搭建育秧环境可自动调控的立体式育秧平台进行试验,控制机器人按照最优轨迹运动,应用高速摄像技术对实际运动轨迹进行记录,试验结果表明,实际轨迹和最优轨迹最大绝对误差为8 mm,在误差允许范围内,可以完成植物工厂内所需的搬运作业功能。     

挖掘机自主挖掘分段可变阶多项式轨迹规划

为保证挖掘机在自主挖掘作业中轨迹平稳连续,降低振动冲击,提出了一种轨迹规划方法,即将作业空间中路径进行合理分段,使其在保证轨迹规划结果中路径偏差较小不影响完成工作任务的前提下计算量尽量减小,并对每一段路径进行可变阶多项式插值轨迹规划。以某型单斗液压挖掘机实现自主挖掘为例,采用3-3-5-3-3多项式插值法进行轨迹规划,通过Matlab平台仿真,结果显示挖掘机各关节角位移、角速度、角加速度曲线平滑连续,但部分轨迹段角加速度超出加速度约束值。为进一步提高其动力学特性,对角加速度不满足要求的轨迹段,根据加速度约束,修正多项式最高阶次数,并利用修正后的高阶多项式进行轨迹规划。通过仿真结果对比,该分段可变阶多项式轨迹规划方法能够实现更加平稳连续的自主挖掘。     

短期放牧对高寒草甸表层土壤入渗和水分保持能力的影响

为深入揭示短期放牧对高寒草甸生态系统地表水文过程的影响机理,基于5个放牧强度(A:2.75只羊/hm~2;B:3.64只羊/hm~2;C:4.35只羊/hm~2;D:4.76只羊/hm~2;E:5.20只羊/hm~2)的3a控制放牧试验,对比研究了表层土壤(0—10cm)物理性状、入渗过程、土壤水分特征曲线及持水和供水能力对放牧强度的响应。结果表明:C处理的土壤初始含水量显著高于D、E处理,但各放牧强度的土壤容重和4个孔隙指标无显著变化;放牧改变了土壤入渗过程,随放牧强度增加,B与C处理入渗较好,D与E处理入渗较差;Gardner模型适用于放牧强度的土壤水分特征曲线拟合,相关系数均达极显著水平,且表征土壤持水性能的a值与低中吸力段含水量表明B与C处理的持水能力高于其它处理;100kPa吸力下比水容量显示,A、B和C处理较D与E处理提高了土壤供水能力。总之,合理放牧强度短期内有利于保存高寒草甸土壤含水量,增强土壤导水性和持水能力,保证土壤有效供水,降低高寒草甸生态系统的退化风险。     

不同放牧强度季节调控对短花针茅草原植物种间关系的影响

【目的】探讨不同放牧强度季节调控方式下短花针茅(Stipa breviflora)荒漠草原植物种关联关系的变化规律,研究不同放牧强度季节调控对荒漠草原植物种间关联性的影响。【方法】以短花针茅荒漠草原植物种为研究对象,在内蒙古苏尼特右旗附近的荒漠草原试验示范基地,设置5个放牧强度季节调控方式和对照(CK)处理,于2013年8月对不同试验处理区植物种存在状况、出现频率及物种间关联性进行调查和统计。【结果】在6个处理区内共发现植物27种,春季零放牧+夏季重度放牧+秋季适度放牧(SA1区)平均物种数最多,对照区最小。从植物种出现频率看,不同放牧强度季节调控方式对3个主要植物种的影响大小依次为碱韭(Allium polyrhizum)无芒隐子草(Cleistogenes songorica)短花针茅,且以春季零放牧+夏季适度放牧+秋季重度放牧(SA2区)的植物种出现频率较低。短花针茅与无芒隐子草主要表现为无关联性,短花针茅与碱韭主要表现为负关联性。春夏秋重度放牧(SA3区)和春夏重度放牧+秋季适度放牧(SA4区)导致显著正相关种对数减少,物种关联链简单,关联物种对较少。春夏秋适度放牧(SA5区)、SA1区及SA2区群落内物种间关联链增多,关联链趋于复杂化。【结论】春季放牧(无论是重度放牧还是适度放牧)均导致植物种总体关联性降低,甚至使植物种总体关联性呈现负关联;春季零放牧有利于植物种间关系的稳定和提高。     

Response of soil water dynamics to precipitation years under different vegetation types on the northern Loess Plateau,China

Implementation of the Grain-for-Green project has led to rapid land cover changes and resulted in a significantly increased vegetation cover on the Loess Plateau of China during the past few decades. The main objective of this study was to examine the responses of soil water dynamics under four typical vegetation types against precipitation years. Soil water contents(SWCs) were measured in 0–4.0 m profiles on a hillslope under the four vegetation types of shrub, pasture, natural fallow and crop in a re-vegetated catchment area from April to October in normal(2010), dry(2011), wet(2014) and extremely wet(2013) years. The results indicated that precipitation and vegetation types jointly controlled the soil water temporal dynamics and profile characteristics in the study region. SWCs in 0–4.0 m profiles of the four vegetation types were ranked from high to low as cropfallowpastureshrub and this pattern displayed a temporal stability over the four years. In the extremely wet year, SWC changes occurred in the 0–2.0 m layer under shrub and pasture while the changes further extended to the depth of 4.0-m deep layers under fallow and crop. In the other three years, SWCs changes mainly occurred in the 0–1.0 m layer and kept relatively stable in the layers deeper than 1.0 m for all the four vegetation types. The interannual variation in soil depth of SWCs was about 0–2.0 m for shrub and pasture, about 0–3.4 m for fallow and about 0–4.0 m for crop, respectively. The dried soil layers formed at the depths of 1.0, 0.6, 1.6 and 0.7 m under shrub, and 1.0, 1.0, 2.0 and 0.9 m under pasture, respectively in 2010, 2011, 2013 and 2014. The infiltrated rainwater mostly stayed in the 0–1.0 m layer and hardly supplied to soil depth 1.0 m in normal, dry and wet years. Even in the extremely wet year of 2013, rainwater recharge depth did not exceed 2.0 m under shrub and pasture. This implied that soil desiccation was difficult to remove in normal, dry and wet years, and soil desiccation could be removed in 1.0–2.0 m soil layers even in the extremely wet year under shrub and pasture. The results indicated that the natural fallow was the best vegetation type for achieving sustainable utilization of soil water and preventing soil desiccation.     

黄花苜蓿个体水平耐牧性的形态学成因机制研究

为揭示黄花苜蓿(Medicago falcata L.)耐牧性的形态学成因机制,探索其耐牧型品种选育的新途径。以从耐牧性鉴定中获得的耐牧性强和弱的2组黄花苜蓿个体植株为材料,对其放牧前后的相关形态指标的观测数据进行分析。结果表明:各形态指标与耐牧性强弱的显著性相关程度依次为根颈宽度>根颈入土深度> 茎数> 株高,对黄花苜蓿耐牧性的促进作用大小依次为根颈入土深度> 根颈宽度> 茎数> 株高> 株丛茎>植株投影盖度。根颈入土深度可单独增强黄花苜蓿的耐牧性,其他性状则通过相互协同作用促进其耐牧性。具有根颈粗大且入土深、单株茎数多且株丛大的黄花苜蓿植株耐牧性强,可作为耐牧育种材料早期选育的形态学指标。     

复合营养调控剂对冷季放牧绵羊肉品质的影响

试验旨在研究不同营养调控剂对冷季放牧绵羊肉品质的影响。采用单因素完全随机区组试验设计,将48只健康、体重相近(28.01±1.70) kg的7月龄放牧母羊随机分为4组,分别为Ⅰ组:不补饲;Ⅱ组:补饲常规精料;Ⅲ组:补饲常规精料+复合配方1组(0.30%苹果酸、0.06%半胱胺、0.08%糖萜素);Ⅳ组:补饲常规精料+复合配方2组(0.60%苹果酸、0.12%半胱胺、0.16%糖萜素)。其中每组3个重复,每个重复4只,试验期45 d,试验期末测定采集各组母羊背最长肌肌肉样品,测定肉质养分、氨基酸的含量。结果显示:①试验Ⅲ组的粗脂肪含量比Ⅰ、Ⅱ和Ⅳ组分别提高27.92% (P < 0.05)、16.67% (P > 0.05)和7.85% (P > 0.05);试验Ⅲ组的粗蛋白质含量比Ⅰ、Ⅱ和Ⅳ组分别提高7.35% (P < 0.05)、3.94% (P > 0.05)和2.49% (P > 0.05);补饲组的剪切力均极显著低于未补饲组(P < 0.01),试验Ⅲ组较Ⅱ组降低3.98% (P < 0.05)。②试验Ⅳ组的脯氨酸含量较Ⅰ和Ⅱ组分别提高38.34% (P < 0.01)和22.75% (P < 0.05),试验Ⅲ组的脯氨酸含量较Ⅰ和Ⅱ组分别提高19.63% (P > 0.05)和6.15% (P > 0.05);其余氨基酸含量在各组之间均差异不显著(P > 0.05)。综上,补饲复合营养调控剂可改善绵羊肉质剪切力,提高绵羊肌内粗脂肪、粗蛋白质和氨基酸含量,改善嫩度风味和营养价值。考虑综合因素,试验Ⅲ组补饲效果最为显著,补饲复合配方1组对改善冷季放牧绵羊肉品质有实际指导意义。     

Individual and socially learned preferences for biserrula (Biserrula pelecinus L.) in sheep

This study examined how sheep develop a learned aversion to the annual legume biserrula (Biserrula pelecinus L.). Merino sheep were grazed on paddocks sown with either (i) biserrula, (ii) biserrula + ryegrass (Lolium rigidum Gaud.), (iii) crimson clover (Trifolium incarnatum L.), (iv) crimson clover + ryegrass or (v) ryegrass, for 4 weeks. Relative preference (Chesson–Manly selection index) was determined by offering randomly ordered monoculture plots of the three forage species. The groups of sheep were then combined into a single group and grazed a paddock containing a monoculture sward of each plant type for 5 d. Relative preference of sheep was tested again after the completion of the combined grazing. The experiment was repeated at three stages of plant phenology: vegetative, reproductive and senesced. Relative preference for biserrula was lower in sheep that had grazed the paddock sown with only biserrula compared with sheep that grazed a combination of biserrula + ryegrass, at both the vegetative (α; −0·11 vs. 0·32) and reproductive (α; 0·18 vs. 0·63) stages. At each stage of phenology, when groups were combined and grazed together, preference for biserrula became uniform. This supported the hypothesis that sheep develop an aversion to biserrula when they graze a pasture containing biserrula. However, we concluded that the familiarity of sheep with biserrula did not result in low relative preference; rather, the aversion was more likely a response to the high proportion of this plant in their diet. Social facilitation may have enabled sheep to overcome rapidly the food aversion.     

Dangerous Relations in the Arctic Marine Food Web: Interactions between Toxin Producing Pseudo-nitzschia Diatoms and Calanus Copepodites

Diatoms of the genus Pseudo-nitzschia produce domoic acid (DA), a toxin that is vectored in the marine food web, thus causing serious problems for marine organisms and humans. In spite of this, knowledge of interactions between grazing zooplankton and diatoms is restricted. In this study, we examined the interactions between Calanus copepodites and toxin producing Pseudo-nitzschia. The copepodites were fed with different concentrations of toxic P. seriata and a strain of P. obtusa that previously was tested to be non-toxic. The ingestion rates did not differ among the diets (P. seriata, P. obtusa, a mixture of both species), and they accumulated 6%–16% of ingested DA (up to 420 µg per dry weight copepodite). When P. seriata was exposed to the copepodites, either through physical contact with the grazers or separated by a membrane, the toxicity of P. seriata increased (up to 3300%) suggesting the response to be chemically mediated. The induced response was also triggered when copepodites grazed on another diatom, supporting the hypothesis that the cues originate from the copepodite. Neither pH nor nutrient concentrations explained the induced DA production. Unexpectedly, P. obtusa also produced DA when exposed to grazing copepodites, thus representing the second reported toxic polar diatom.     

不同降雨年份和放牧方式对荒漠草原初级生产力及营养动态的影响

牧草品质直接体现了草地资源的质量和可利用性。本研究采用野外调查法对不同降雨年份和放牧方式下荒漠草原植物群落的地上净初级生产力(ANPP)、粗蛋白、粗纤维、粗灰分、粗脂肪、钙、磷和无氮浸出物进行了测定和分析。结果表明,1)在干旱的2011年,自由放牧显著降低了群落的ANPP,而在降雨量充足的2012年,休牧60 d的ANPP值最高;2)相比于欠雨年份,降雨量充足的年份生长高峰期ANPP、粗蛋白、粗灰分、钙和磷的含量分别是其的2.67,1.08,1.27,1.26和3.75倍;3)相比其他处理,粗蛋白、磷的含量在休牧60 d含量最高;4)在不同降雨量的两个放牧季节内,随着放牧的进行,粗蛋白、粗脂肪、粗灰分、钙和磷的含量呈现先增加后降低的趋势,均是在7或8月份达到一个峰值,而在植物枯黄期(10月份)值最低,而粗纤维和无氮浸出物的含量在7月份最低,而在植物枯黄期最高。降雨量与荒漠草原植物群落ANPP及植物群落营养季节动态之间存在着密切的关系;休牧60 d为合理的草原利用方式;不同年际间放牧和季节气候变化共同制约了群落营养成分的变化。