Evaluation of agreement among digital dermatitis scoring methods in the milking parlor,pen, and hoof trimming chute

Digital dermatitis (DD) is the most common infectious foot lesion affecting welfare and productivity of dairy cattle. The key to DD control programs is routine and frequent identification of DD lesions. The objective was to evaluate accuracy of detecting and scoring DD lesions in 3 milking parlor designs and in 3 alternative settings compared with scoring in the hoof trimming chute as reference. A total of 552 cows and 1,104 hind feet from 17 freestall farms were scored by 1 observer in the milking parlor and in 1 other setting: pen, headlocks, or management rail. After being scored in the milking parlor and at least 1 other setting, cows were examined in the hoof trimming chute, considered the gold standard. In every setting, all hind feet were inspected visually using a flashlight and without prior washing of feet. Agreement of the scoring settings was assessed using the 5 M-stage scoring system and a dichotomous absence (M0 or M0/M1) or presence (M1 to M4.1 or M2 to M4.1) system. At trimming chute inspection, 44% of feet had a DD lesion, with estimates of 11, 5, 2, 10, and 16% for M1, M2, M3, M4, and M4.1 lesions, respectively. Apparent DD foot-level prevalence at the milking parlor, pen, management rail, and headlocks was 28, 22, 16, and 22%, respectively. M-stages were less discernible in the pen, management rail, and headlocks (apparent prevalence of M1, M2, M3, and M4.1 was ≤1%) compared with the trimming chute and milking parlor. Agreement beyond chance between any scoring setting and trimming chute scoring ranged from 0.48 to 0.70 for the dichotomous scoring system (absence = M0/M1 vs. presence = M2 to M4.1). Diagnostic test performance varied greatly among DD scoring settings but, in general, it had low sensitivity (<70%) and high specificity (>93%) for detecting any DD lesion. Agreement and test characteristics were not affected by the type of milking parlor. Although the milking parlor and headlocks were the most reliable settings in which to detect DD, none of the settings were reliable enough to replace inspection of feet in the trimming chute. However, scoring the presence or absence of DD in the milking parlor, pen, management rail, and headlocks could be used to estimate within-herd DD prevalence, to improve DD surveillance through routine monitoring, and to evaluate effects of interventions at the farm level.     

基于激光刻蚀技术石英晶振频率微调系统的设计

根据石英晶振频率微调机理及激光刻蚀特性,设计软件、硬件实现了一个基于PC机和激光器的石英晶振频率微调装置,并提出了一种实用刻蚀方案,可实现对多片晶片同时微调,能有效地消除微调过程中出现的温漂等问题,同时讨论了提高微调速度及合格率的方法．     

零件大回弹量时修边线的计算方法

在模具设计中怎样准确计算翻边零件的修边轮廓仍是模具行业的一大难题.许多论文曾提出一些修边线的计算方法,但是一般未考虑到后续回弹过程的影响,尤其是有大的回弹时,这些方法得到的结果就更加不准确了.为了解决大回弹量时的修边线确定问题,研究了有限元变形路径迭代的基本算法,分析了修边轮廓切除、增补过程,回弹的基本解决方法.最后提出了一种考虑大回弹时的修边线确定方法.通过对某汽车底板主保险杠修边线的计算,验证了该方法计算结果的可靠性及在工程上的可行性.     

影响六角切边模使用寿命的主要因素

对影响六角切边模使用寿命的主要因素进行了详细分析。结果表明 :模具结构、模具材料及热处理是关键性因素 ;被加工材料、产品规格、机械加工及现场生产条件等有较大影响,在此基础上研制开发的不同规格的六角切边模新产品 ,经生产应用表明 :其使用性能和寿命与国外同类模具的水平相当。     

集成SolidWorks平台的修边线展开与翻边成形同步模拟系统

基于SolidWorks平台开发了三维修边线展开及翻边成形参数化同步更新模拟系统(SW-TUX),实现了CAE分析环境与CAD的无缝集成,避免了数据转换带来的精度损失。借助SolidWorks二次开发API工具,结合翻边成形的实际工艺流程,设计了工艺操作树和开放式材料库,研究了网格的智能修复技术以及翻边过程中边界约束处理方法。充分利用SolidWorks参数化建模功能,在翻边成形工艺中引入参数化思想,实现了翻边成形模拟过程的参数化同步自动更新,实时反馈设计变更的可行性和实用性。结合实例进行模拟分析,验证了该系统的可行性。     

Ar+激光器用于电阻微调的研究

本文讨论并研究了Ar+激光器用于电阻微调的优越性。结果表明,在比常用的Nd:YAG激光功率小得多的情况下,可得到与之相当的刻线宽度和阻值稳定性。     

翻板式半自动轮胎修毛机的改进

介绍翻板式半自动轮胎修毛机的工作流程、存在问题以及改进措施和效果。通过采取改进进出通道辊筒、修毛工位设置防静电软毛刷装置、改进翻板机构以及对主动辊筒驱动电机实施变频控制措施,使轮胎平均修毛时间由12 s缩短为8 s,同时延长了设备使用寿命,减轻了工人劳动强度。     

断路器DMC零件加工方案及去飞边工装设计

热固性不饱和聚酯玻璃纤维增强模塑料(DMC)制件主要存在加工效率低、后处理成本高的工艺难题,分析了DMC压塑成型、注塑成型、传递成型的工艺方案特点,给出了断路器中DMC制件的加工工艺方案选择原则。针对压塑加工件,采用塑壳底座气动去飞边工装设计,极大地提升了塑件后处理效率。     

Short communication: Use of lameness scoring to genetically improve claw health in Austrian Fleckvieh,Brown Swiss,and Holstein cattle

The specific objective of this study was to evaluate the use of lameness scoring to genetically improve claw health in Austrian Fleckvieh, Brown Swiss, and Holstein cows based on data from the “Efficient Cow” project. In 2014, a 1-yr data collection was carried out. Data from 6,519 cows kept on 161 farms were recorded. At each time of milk recording, lameness scores were assessed by trained staff of the milk recording organizations. Hoof trimming on these farms was documented and recorded as well. Veterinarian diagnoses and culling due to foot and leg problems from these farms were available from the routine recording system. As repeated lameness records per cow and lactation were available, an overall lactation lameness score was calculated. Estimated heritabilities for lameness were 0.11, 0.05, and 0.09 for Fleckvieh, Brown Swiss, and Holstein, respectively; however, only heritability estimates for Fleckvieh were significantly different from zero. Breeding values for lameness were obtained, reversed in sign, and cows were ranked according to their breeding value. A low breeding value for lameness resistance (the bottom 10% of the cows) was associated with a significantly higher frequency of trimmed cows, which indicates that the cows selected by the farmer to be trimmed are not completely random. Additionally, a high breeding value for lameness resistance (the top 10% of the cows) was associated with lower frequencies of claw diseases recorded at trimming, claw and leg diagnoses, and culling due to foot and leg problems, which highlights the usefulness of lameness scoring for genetic improvement of claw health. Overall, selecting for a better lameness score has the potential to reduce claw diseases, especially the frequency of severe claw diseases that lead to culling.     

The effect of preventive trimming on weight bearing and force balance on the claws of dairy cattle

Claw disorders and lameness in dairy cattle are an increasing problem of the modern dairy industry. To prevent claw disorders from evolving from the subclinical to the clinical stage, trimming is the management practice most routinely applied. The goal of preventive trimming (Toussaint-Raven method) is to promote natural loading by increasing the weight-bearing contact area of the claws and improving the balance between the medial and lateral claw. The biomechanical effect of preventive claw trimming was investigated with the aid of pressure distribution and ground reaction force recordings of the standing cow sampled simultaneously at 250 Hz. It appeared that preventive trimming of the hind limbs (n = 10) brought the claws slightly more in balance. Before trimming, 80% of the total force is taken up by the lateral claw and 20% by the medial claw. After trimming, this becomes 70 to 30%, respectively. Thereby, a significant increase in the weight-bearing contact area from 27.5 to 40.0 cm2 was achieved, resulting in a significant decrease in average pressure. However, the claws remained subjected to unaltered, high maximum pressures after trimming. The suggestion was made that the main focus of claw trimming should not be force balance; instead, a reduction of local maximum pressures at the contact area should be targeted in such a way that the strongest parts of the claw capsule (i.e., the wall) will be subjected to the highest pressures.