Small-radius turning performance of an articulated vehicle by direct yaw moment control

This paper reports the turning performance of an articulated vehicle in which applying direct yaw-moment control is applied to reduce the turning radius. In the proposed method, a braking force is applied to the inner tires when the articulation angle reaches its maximum in turning, which generates a yaw-moment around the vehicle's centre of gravity. The yaw-moment allows the vehicle to turn in a small radius. To evaluate the performance in tight turns, experiments were conducted using a wheel loader on paved ground. The vehicle's turning radius, yaw rate and side-slip angle were determined from the data measured using two global positioning systems and a fibre-optic gyro sensor. In addition, results of a simulation were compared with experimental results from a test vehicle. The turning radius at a braking pressure of 4 MPa was at least 0.41 m smaller than that of 0 MPa. Experimental and simulated results proved that generating a yaw-moment by applying one-sided braking forces during turning decreases the turning radius.     

中原经济区农业现代化的状态评价与定位推进

在梳理农业现代化相关研究的基础上,构建农业现代化综合评价体系,基于熵权灰色关联模型与空间分析方法对中原经济区农业现代化水平的时空变化规律进行分析。结果表明,时序特征方面,农业现代化综合水平除1997年出现小幅下降外不断提高,并且2002年之后增长幅度较大。其中农业经济发展水平、农业生产条件与生产效率水平呈现较稳定的增长;农村社会发展水平与整体变化类似,但2008年出现下降,且2009之后增长幅度有所下降;农业生态环境水平波动变化较大,呈现不稳定状态。从空间分异情况看,郑州、焦作、襄阳三市的农业现代化水平与其他地区差别较大,其余地区相邻之间的差距较小,农业现代化水平的等级层次相对不明显。从整个分布格局看,第三、第四、第五级别区组成的区域占据了绝对主导并形成大范围连绵分布区,第一、第二级别区分布范围小且在郑州及其北侧小范围集中,整个区域的分布格局极其不平衡且局部差异大。基于评价结果进行了原因解读,并从时空两个维度提出了定位推进建议。     

乡村振兴战略背景下农业职业教育角色定位研究

实施乡村振兴战略是全面建设社会主义现代化强国的重大战略决策和历史任务.北京农业职业学院充分发挥职业教育和农业行业复合功能及区位优势,构建以"政校行企"为载体,服务乡村产业振兴、组织振兴、生态振兴、文化振兴、人才振兴为核心的"五位一体"教育培训服务体系,全面服务首都乡村振兴,乡村人才培养质量、服务乡村振兴水平显著提升,产生巨大社会影响.     

Computed tomographic anatomy of the temporomandibular joint in the young horse

Reasons for performing study: The equine temporomandibular joint (TMJ) and its surrounding structures can be difficult to investigate in cases with a clinical problem related to the region. Little previous attention has been given either to a computed tomographic (CT) imaging protocol for the joint or an interpretation of the structures displayed in CT images of the normal joint. Objectives: To provide a CT atlas of the normal cross‐sectional anatomy of the equine TMJ using frozen and plastinated sections as anatomical reference. Methods: Eight TMJs from 4 immature pure‐bred Spanish horses were examined by helical CT. Scans were processed with a detailed algorithm to enhance bony and soft tissue. Transverse CT images were reformatted into sagittal and dorsal planes. Transverse, sagittal and dorsal cryosections were then obtained, photographed and plastinated. Relevant anatomic structures were identified in the CT images and corresponding anatomical sections. Results: In the CT images, a bone window provided excellent bone detail, however, the soft tissue components of the TMJ were not as well visualised using a soft tissue window. The articular cartilage was observed as a hyperattenuating stripe over the low attenuated subchondral bone and good delineation was obtained between cortex and medulla. The tympanic and petrous part of the temporal bone (middle and inner ear) and the temporohyoid joint were seen in close proximity to the TMJ. Conclusions: Helical CT provided excellent images of the TMJ bone components to characterise the CT anatomy of the normal joint. Potential relevance: Detailed information is provided that may be used as a reference by equine veterinarians for the CT investigation of the equine TMJ and serve to assist them in the diagnosis of disorders of the TMJ and related structures (middle and inner ear). The study was performed at an immature stage and further studies of mature individuals are required in order to confirm that the clinical interpretation is not affected by changes occurring with age.     

COMPUTED TOMOGRAPHIC FINDINGS OF DOGS WITH CUBITAL JOINT LAMENESS

The purpose of this study was to identify the incidence of abnormal computed tomography (CT) findings in dogs with lameness of one or both elbows. CT examinations of 102 elbows in 51 dogs were reviewed individually and by group consensus by 3 examiners and graded for various abnormalities. Frequently encountered abnormalities included abnormal shape and sclerosis of the medial coronoid process of the ulna, irregularity of the radial incisure of the ulna, and ulnar trochlear notch sclerosis. Other abnormalities included distinct/separate or fissure/in situ fragmentation of the medial coronoid; lucency of the radial incisure; ununited anconeal process; sclerosis, lucency, or flattening of the medial aspect of the humeral condyle; osteophyte formation; and joint incongruity. In conclusion, CT of the canine cubital joint is useful in identification of various lesions beyond simple fragmentation of the medial coronoid process of the ulna.     

Epidemiological features and association with crib‐biting in horses with neurological disease associated with temporohyoid osteoarthropathy (1991–2008)

A retrospective study of 43 cases of temporohyoid osteoarthropathy was performed to evaluate the epidemiological features and a possible association with crib‐biting. Data collected from records included case details, what diagnostics were utilised, whether medical or surgical treatment was administered, and outcome. Owners were contacted via telephone and asked whether the horse had displayed crib‐biting behaviour. Forty‐three horses were diagnosed with neurological disease associated with temporohyoid osteoarthropathy, 62.8% of which were Quarter Horse‐types. Median age at presentation was 10 years and median duration of neurological signs prior to presentation was 3 days. Skull radiographs and guttural pouch endoscopy were used to definitively diagnose temporohyoid osteoarthropathy in 72% of the cases. Of 43 horses, 21 received medical treatment and 15 surgical treatment, with an overall survival rate of 55.8%. Crib‐biting was observed in 31.3% of cases and there was a significant association between being afflicted with THO and likelihood of possessing the behaviour. Horses with neurological disease associated with THO were 8 times more likely to be crib‐biters compared to the general population.     

基于Kalman滤波的田间导航车辆定位校正方法研究

以装载了RTK-DGPS导航系统的KUBOTASPU-68水田插秧机为试验平台,以姿态测量系统提供载体姿态信息,研究农业机械导航的姿态校正方法。在分析车载GPS倾斜误差产生原因基础上,提出了采用多传感器联合测量载体姿态角以提供校正信息。采用MEMS传感器集成模块ADIS16355作为惯性测量单元,卡尔曼滤波实现传感器信息融合以计算姿态角,设计了姿态测量系统。阐述了两种传感器融合测量实时姿态角的算法,基于ARM7Cotex-M3微处理器设计了姿态测量系统硬件。