Effects of Large Saddle Panels on the Biomechanics of the Equine Back During Rising Trot: Preliminary Results

The saddle panels, directly in contact with the horse's back, are likely an important element to optimize the fitting of the saddle, the comfort of the horse, and subsequently, the pain management in dorsalgic horses. The aim of this study was to better understand the effect of the saddle panels on the horse's back, by evaluating a prototype saddle (comfort panels: CP) compared to a standard saddle (STD). The horse's back movements were measured using inertial measurement units (IMUs) fixed at the levels of thoracic vertebrae T6, T12, T16 (under the saddle) and lumbar vertebrae L2 and L5. The centers of mass (COMs) of the horse and the rider and limb's protraction-retraction angles, pressure between saddle and horse's back, and force on the stirrups were measured using respectively 2D motion capture, pressure mat and force sensors in the stirrup leather. Three horses were trotted at the rising trot (sitting: left diagonal-rider seated; standing: right diagonal-rider standing) by the same rider. To compare saddles, linear mixed-effects regression models were used. The estimated means (SE) were calculated. During sitting phase, pressure in the cranial and middle areas of the saddle significantly increased for CP compared to STD (+0.9 (0.2) kPa and +1.0 (0.1) kPa, respectively) whereas caudal pressure decreased (−1.8 (0.4) kPa). Concurrently, the range of motion of angles T12-T16 and T16-L2 under the saddle significantly increased (+1.8 (0.2)° and +2.3 (0.3)°, respectively). The results showed that modifications of the panels' shape not only affect the pressure distribution but also the kinematics of the thoracic and lumbar regions of the equine back.     

对小水电、沼气池、省柴灶三个能源工程项目的综合评价

农村能源工程项目的建设不仅具有项目本身的经济效益，而且有更广泛的能源、间接的经济和生态效益。农村能源工程项目的建设除了受资金约束外，还有技术管理等方面的限制，甚至人们的习俗和心理状态都可能是能源工程项目的制约因素。因此，对农村能源工程项目的多种效益和多种制约的综合分析和评价，将使我们能更全面地考虑项目的综合效果，使有限的资金、人力、物力投入到综合效果最好的项目上去。     

Characterizing historical and modern fire regimes in Michigan (USA): A landscape ecosystem approach

We studied the relationships of landscape ecosystems to historical and contemporary fire regimes across 4.3 million hectares in northern lower Michigan (USA). Changes in fire regimes were documented by comparing historical fire rotations in different landscape ecosystems to those occurring between 1985 and 2000. Previously published data and a synthesis of the literature were used to identify six forest-replacement fire regime categories with fire rotations ranging from very short (<100 years) to very long (>1,000 years). We derived spatially-explicit estimates of the susceptibility of landscape ecosystems to fire disturbance using Landtype Association maps as initial units of investigation. Each Landtype Association polygon was assigned to a fire regime category based on associations of ecological factors known to influence fire regimes. Spatial statistics were used to interpolate fire points recorded by the General Land Office. Historical fire rotations were determined by calculating the area burned for each category of fire regime and dividing this area by fifteen (years) to estimate area burned per annum. Modern fire rotations were estimated using data on fire location and size obtained from federal and state agencies. Landtype Associations networked into fire regime categories exhibited differences in both historical and modern fire rotations. Historical rotations varied by 23-fold across all fire rotation categories, and modern forest fire rotations by 13-fold. Modern fire rotations were an order of magnitude longer than historical rotations. The magnitude of these changes has important implications for forest health and understanding of ecological processes in most of the fire rotation categories that we identified.This revised version was published online in May 2005 with corrections to the Cover Date.     

3D打印技术在水利水电工程施工中应用研究

对3D打印技术进行应用研究,阐述其精度、强度和速度等关键性能指标合理性,能够有效避免特殊形式结构部位的施工带来的成本、工期及质量问题,增加工程效益,并对溢流堰面特殊部位计算表面曲线轮廓,进行实验3D打印,最后总结3D打印在水利水电工程施工中的优势。     

模糊故障诊断在水电机组中的应用

根据水轮发电机组的振动特点，本文探讨了适合于水轮发电机组的振动故障诊断方法，提出了将模糊技术应用于水轮发电机组振动故障诊断的思想，简要阐述了模糊故障诊断的基本原理，列出了水轮发电机组的征兆集和故障集，并根据征兆集和故障集的相互关系，提出了相应的模糊关系矩阵。最后通过模糊关系矩阵的运算，确定水轮发电机组的故障模糊向量。并以实际机组的振动故障为实例，验证模糊故障诊断方法的可行性和优越性。     

农业科研单位创新文化建设途径探析

科技进步离不开科技创新,科技创新又需要创新文化的支持,文章分析了农业科研单位创新文化的现状及存在的问题,提出从更新观念树立以人为本的思想、倡导追求科学真理宽容失败的科学精神、加强管理体制和机制的创新、加强精神文明建设等方面构建创新文化。     

Bush cover and range condition assessments in relation to landscape and grazing in southern Ethiopia

Progressive growth of bush cover in dry savannahs is responsible for declines in range conditions. In southern Ethiopia, the Booran pastoralists assisted our understanding of spatial patterns of bush cover and range conditions in 54 landscape patch types grouped into six landscape units within an area of 30000 km². The size of landscape patches sampled was 625 m². We assessed the relationships between bush cover, grass cover and bare soil and grazing pressure and soil erosion and changes in range condition. Externally, political conflicts and internally, break down of land use, and official bans on the use of fire promoted bush cover and the decline in range conditions. Bush cover was negatively correlated with grass cover, and positively correlated with bare soil. Grass cover was negatively correlated with bare soil and grazing pressure in most landscape patch types. Grazing pressure was not significantly correlated with bush cover or bare soil, while soil erosion was directly related to bare soil. Soil erosion was absent in 64% of the landscape patch types, and seemingly not a threat to the rangelands. The relationship between bush cover, grass cover, bare soil and soil erosion is complex and related to climate, landscape geology, and patterns of land use. Main threats to range conditions are bush climax, loss of grass cover and unpalatable forbs. Currently, >70% of the landscape patch types are in poor to fair range conditions. Decline in range conditions, unless reversed, will jeopardise the pastoral production system in southern Ethiopia.     

基于神经网络逆控制方法的水轮发电机组非线性控制器仿真研究

基于水轮发电机组刚性水击模型和神经网络逆系统控制方法,在分析励磁与导叶系统可逆性的基础上提出了一种新的水轮发电机组解耦控制器设计方法.理论分析和仿真结果表明该控制策略较好的解决了水轮发电机组控制时存在的多变量、非线性、强耦合问题;实现了系统的动态解耦控制,具有较好的适应性和鲁棒性,因此可有效增强输电系统的暂态稳定性.     

强化基层林业站职能作用 促进林业跨越式发展

基层林业站是国家设在基层的林业管理机构 ,在林业生产和建设中发挥着重要的职能作用。强化林业站的职能作用 ,必将对推动我国六大林业重点工程建设 ,实现林业跨越式发展起到巨大作用。     

农产品质量安全科研检测单位的劳务派遣用工管理

受人员编制限制,人力资源相对不足制约了农产品质量安全科研检测单位的发展。劳务派遣作为一种新型用工形式,一定程度上解决了农产品质量安全科研检测单位的人力资源配置问题。文章对农产品质量安全科研检测单位劳务派遣用工管理进行解析,分析存在的问题,并提出一些对策,以期对农产品质量安全科研检测单位的劳务派遣运用有所启示。