马铃薯相对分离筛运动位移分析与分离筛性能试验

为解决摆动分离筛薯土分离机理不明确,分离筛参数匹配不尽合理的问题。通过田间试验,获得了无土和有土筛面上马铃薯相对分离筛的位移随曲柄转速、筛面倾角和机器前进平均速度等参数的变化规律,以及分离筛性能指标随参数的变化关系。试验结果表明:马铃薯相对分离筛位移的波动幅度随着曲柄转速的升高而先增大后减小,筛面倾角越大马铃薯相对分离筛位移的波动幅度越小,机器前进平均速度越大位移的波动幅度越大;有土筛面上马铃薯相对分离筛位移的波动幅度较无土筛面上马铃薯位移的波动幅度大;明薯率和破皮率随着曲柄转速的增加而先增大后减小,随着筛面倾角的增大而先减小后增大;机器前进平均速度对明薯率影响不明显,破皮率随着机器前进平均速度的增加而先减小后增大。     

ULTRASONOGRAPHIC ASSESSMENT OF LARYNGOHYOID POSITION AS A PREDICTOR OF DORSAL DISPLACEMENT OF THE SOFT PALATE IN HORSES

Dorsal displacement of the soft palate is an important cause of poor performance in racehorses, yet its etiology is not fully understood. Diagnosis requires treadmill videoendoscopy, which is not widely available. The relationship of the larynx, the hyoid apparatus, and the remainder of the skull may be important in predisposing horses to dorsal displacement of the soft palate. We hypothesized that this relationship could be accurately assessed in unsedated horses through ultrasonographic examination. Fifty-six racehorses presented for evaluation of poor performance were subjected to treadmill videoendoscopy and resting ultrasonography. Using ultrasound-assisted percutaneous measures of laryngo-hyoid position, the relationship between selected anatomic structures and the occurrence of dorsal displacement of the soft palate was evaluated. A significant relationship was found between the depth of the basihyoid bone at rest and the occurrence of dorsal displacement of the soft palate at exercise ( P =0.03). Other measures of laryngohyoid position were not found to be associated with dorsal displacement of the soft palate. Thus, there is an association between the occurrence of dorsal displacement of the soft palate at exercise and the resting position of the basihyoid bone, whereby on average a more ventral location of the basihyoid bone is present in horses with dorsal displacement of the soft palate. The pathophysiologic implications of this finding are not fully understood but, based on our findings, ultrasound examination is of value in assisting in the diagnosis of dorsal displacement of the soft palate.     

横向滑坡过程中管道的内力和变形计算

将滑坡体中的管道简化成大挠度的梁,将滑坡体外管道看作半无限长的梁或杆,考虑管梁的几何非线性、滑坡体外土壤的纵向抗力的物理非线性以及管道的内压和温差作用,基于滑坡体内外管道内力和变形的连续性,推导得出了在当量轴向力为拉力或压力两种情况下管道的内力和位移的有关计算式,提出了当量轴力为拉力或压力的判别式。横向滑坡中埋地管道的位移和内力计算最终归结于两个非线性方程的求解,可用牛顿迭代法或作图法解之。提供了     

基于角位移控制的功率分流式自动变速器速比控制研究

阐述了功率分流式自动变速器中电机控制式无级变速单元的速比控制原理。通过对速比控制电机目标角位移、角位移滑模变结构控制器的建模,来确定整个控制器的设计参数。在对角位移目标轨迹跟踪的仿真中,控制器能够较好地实现在有外在负载干扰下对角位移目标轨迹的跟踪。     

基于MATLAB的空间7R机构位置分析的新方法

利用向量回转法和MATLAB软件对空间7R机构位置问题进行了分析研究，确定了各杆长和副长方向的单位向量，列出了机构的向量封闭方程，以及各杆位置方程；调用MATLAB矩阵运算函数和解非线性方程组函数，解出了其他各杆的位置与主动件输入角度的关系，以及任何一杆上任意点的空间轨迹，并利用绘图函数表达各杆的位置曲线及任意点的轨迹。实例分析证明所提出的方法是可靠的。     

Looking back on development and disaster‐related displacement and resettlement,anticipating climate‐related displacement in the Asia Pacific region

The realisation that climate change might necessitate resettlement of people displaced initially raised interest in the experience of development‐forced displacement and resettlement (DFDR). Looking back, in 1980 the first international policy on involuntary resettlement was approved to address perceived weaknesses in state property and expropriation law to safeguard people in the way of development projects. Since then international policy and praxis have brought global attention to developmentally displaced people but have not guaranteed them an effective safeguard. Recently, renewed attention has focussed on state legal and governance frameworks substantively and procedurally. Identifying four key policy objectives that resonate with climate change displacement I analyse their treatment in a data base of DFDR laws and regulations from 40 Asia Pacific states. This analysis finds overall little legal congruence. Innovative new formulations in some Asian state laws address recent public criticisms and research findings, but mostly are yet to demonstrate positive outcomes for displaced people. Pacific states increasingly abandon expropriation law to negotiate lease terms for public infrastructure projects with customary landowners that do not extinguish customary title. Any laws governing climate change relocations must protect rights, livelihoods, well‐being, inclusive decision‐making and community initiatives with procedures whilst not relinquishing climate‐change‐reducing action.     

Modern forestry vehicles and their impacts on soil physical properties

“Close-to-nature forest stands” are one central key in the project “Future oriented Forest Management” financially supported by the German Ministry for Science and Research (BMBF). The determination of ecological as well as economical consequences of mechanized harvesting procedures during the transformation from pure spruce stands to close-to-nature mixed forest stands is one part of the “Southern Black Forest research cooperation”. Mechanical operations of several typical forest harvesting vehicles were analysed to examine the actual soil stresses and displacements in soil profiles and to reveal the changes in soil physical properties of the forest soils. Soil compaction stresses were determined by Stress State Transducer (SST) and displacement transducer system (DTS) at two depths: 20 and 40 cm. Complete harvesting and trunk logging processes accomplished during brief 9-min operations were observed at time resolutions of 20 readings per second. Maximum vertical stresses for all experiments always exceeded 200 kPa and at soil depths of 20 cm for some vehicles and sequences of harvesting operations approached ≥500 kPa. To evaluate the impacts of soil stresses on soil structure, internal soil strengths were determined by measuring precompression stresses. Precompression stress values of forest soils at the field sites ranged from 20 to 50 kPa at soil depths of 20 cm depth and from 25 to 60 kPa at soil depths of 40 cm, at a pore water pressure of −60 hPa. Data obtained for these measured soil stresses and their natural bearing capacities proved that sustainable wheeling is impossible, irrespective of the vehicle type and the working process. Re-occurring top and subsoil compaction, increases in precompression stress values in the various soil horizons, deep rut depths, vertical and horizontal soil displacements associated with shearing stresses, all affected the mechanical strengths of forest soils. In order to sustain naturally “unwheeled” soil areas with minimal compaction, it is recommended that smaller machines, having less mass, be used to complete forest harvesting in order to prevent or at least to maintain currently minimal-compacted forest soils. Additionally, if larger machines are required, permanent wheel and skid tracks must be established with the goal of their maximum usefulness for future forest operations. A first step towards accomplishing these permanent pathways requires comprehensive planning with the Federal State Baden-Württemberg. The new guideline for final opening with skid tracks (Landesforstverwaltung Baden-Württemberg, 2003) proposes a permanent skid track system with a width of 20–40 m.     

适用于梯级泵站压力管道的传感器优化布置方法

为解决梯级泵站压力管道传感器优化布置问题,提出一种基于有效独立-总位移法的传感器优化布置方法。该方法针对有效独立法所选测点能量较小的缺陷,将测点的总位移以权重的方式加入传感器优化过程中,并保留有效独立法的优点,最终得到独立性较好且满足能量要求的测点。以景泰压力管道为例,运用该方法进行传感器优化布置,并与传统有效独立法比较,通过模态置信准则、Fisher信息矩阵值、最大奇异值比以及总位移等指标评价2种方法的优劣。结果表明,有效独立-总位移法得到的测点在满足独立性的前提下,增加了测点信息量,可观性更好。优化前后实测数据的比较分析,表明该方案对实际结构检测具有较好的适用性,是一种实用有效的传感器优化布置方法。     

基于稀土超磁致伸缩材料的微致动器设计

选择Terfenol-D作为微致动器主要材料，采用弹簧对GMM棒施加一定的预压力以获得较大的磁致伸缩应变，采用偏置磁场消除GMM棒的倍频现象并使之工作在线性段，对磁路进行了分析和优化设计。针对电磁线圈工作发热及涡流损耗引起的GMM棒温升，采取了强制水冷方法并专门设计了一个恒温冷却系统用以消除材料的热变形对致动精度的影响。     

差动制动对制动稳定性的影响

分析了差动制动的力学特性,并通过ADAMS/CAR建立整车仿真模型,对不同制动初速度下的直线制动及转弯制动进行仿真分析。结果表明,差动制动方式可以减小汽车制动时的侧向位移量;转弯制动时,内轮施加制动力可改善转向不足,外轮施加制动力可改善过度转向;内后轮与外前轮对于制动稳定性影响较大。