融合功能倒推与裁剪法的系统创新设计方法*

裁剪法是产品改进创新的重要方法,而功能分析是实施裁剪的基础。对于复杂机械系统,功能分析常常面临组件层级难以确定的问题,依赖设计者个人理解和经验判断,操作上存在较大的主观性,不同设计者分析过程和结果往往差异较大。为提高功能分析客观可操作性,基于逆向工程思维,提出了由系统目标向系统内部组件逐步遍历的功能倒推分析法。该方法专注于接触界面,从系统主要功能的目标对象开始,通过相互作用分析倒推功能载体,逐层循环迭代倒推直至遍历所有组件。进一步,结合功能倒推分析法与裁剪法,运用TRIZ问题求解工具,建立系统重构创新设计过程模型。最后,以钢轨铣磨车磨装置为例进行系统重构创新设计,验证了功能倒推分析法和系统重构创新设计方法的实用性和有效性。     

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。     

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.     

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.     

传统荷包边饰艺术分析

为了复原传统荷包工艺艺术的边饰工艺,对江南大学民间服饰传习馆、台州刺绣博物馆300余件荷包传世藏品的边饰进行分类研究,发现荷包边饰主要有编织带镶边、布条滚边和股线绣边3种基本形式。其中,织带镶边在葫芦荷包、扇套、眼镜袋等荷包中常见;布条滚边在江南腰包中最为普遍;股线绣边工艺最复杂,在装饰性强的方荷包、圆荷包中应用最多。可见,风格粗犷的大型荷包以布条滚边为主,精细绣花的小型荷包多以绣边装饰,织带镶边则具有一定的装裱作用。荷包边饰艺术融合了传统纹饰设计、配色、编织与刺绣等工艺。边饰选择遵循衬托点缀和功能适宜原则,荷包的造型类别、装饰风格以及制作材料共同决定了荷包边饰类型。     

超声珩磨油石修整技术研究(1)

通过对超声珩磨油石专用工装的设计、制造及修整参数试验,给出了磨削工程陶瓷等超硬材料时超声珩磨油石修整的工艺规范．同时,借助电镜和表面轮廓仪考察了不同参数下超声珩磨油石的修整地貌及磨削表面形貌．研究表明：用磨削法修整结合剂密实型超声油石,其磨粒突出高度据不同修整参数可以满足超硬材料加工的不同要求,所设计的专用工装简单易行．     

高比转数双吸离心泵叶轮切割内部流场数值模拟

为深入分析叶轮切割对高比转数双吸离心泵内部流动状况及性能的影响,采用数值方法对三台高比转数双吸离心泵进行了叶轮切割研究,对每台泵所装叶轮均进行4次切割;预测得到了泵的H-Q、η-Q、P-Q特性曲线与内部流场压力、速度等参数的分布云图及其随叶轮切割的变化情况,根据性能预测结果得到了最优工况下叶轮的切割指数。结果表明,当叶轮逐步切割时,泵的流量、扬程、轴功率均逐步降低;切割量较小时,泵的效率基本不变;随着切割量的增大,泵的效率开始下降,当切割量达到15%时效率下降明显;随着叶轮直径的逐步减小,泵内部压力场及速度场分布不均匀性增加;由数值计算所求得的切割指数与传统切割公式中的切割指数存在不一致性。     

蓄能机组轴线问题及机组运行摆度偏高分析处理

十三陵蓄能电厂针对机组运行中水导摆度过大的问题,特别是2号机组在安装期间进行过加垫调整轴线,对全厂4台机组的轴线进行了彻底检查。本文通过对2号机组的轴线调整阐述了可逆式、高转速、高水头蓄能机组的轴线调整,从各方面分析了影响机组运行摆度的可能原因。