结构逻辑(SL)及其对并行机器的描述

本文首先介绍了结构逻辑(SL)以及其对几种并行模型的描述,然后讨论了并行程序的自动综合和正确性证明。最后用结构逻辑刻划了扩展Petri-网中计算模型并发性。     

Nitrogen supplementation of corn silages. 1. Effects on feed intake and milk production of dairy cows

Feed intake and milk production responses to N supplementation of corn silage-based diets were measured in three 3 x 3 Latin square experiments. In each experiment, 9 Holstein cows received total mixed rations (TMR), based on corn silage. In Exp. 1, midlactation cows were used to study effects of diets with different ratios of effective rumen-degradable protein (ERDP; g) to fermentable metabolizable energy (FME; MJ), providing a large deficiency (RL), a slight deficiency (RM), and a slight excess (RH) in relation to the target level of 11 g of ERDP/MJ of FME, respectively, for lactating cows. Diets were formulated to be isoenergetic, and to satisfy the metabolizable protein requirements. In Exp. 2, early-lactation cows were used to evaluate effects of different proportions of quickly and slowly rumen-degradable protein (RDP), achieved by replacing soybean meal with urea in the concentrates (0, 0.5, and 1% urea). Experiment 3 investigated effects of synchronizing the availability of FME and ERDP in the rumen. Midlactation cows received a diet containing, on a dry matter (DM) basis, 45% corn silage, 5% ryegrass hay, 35% energy-rich concentrate, and 15% protein-rich concentrate (crude protein: 38% of DM; urea: 2% of DM). The protein-rich concentrate was fed either once (D1) or twice (D2) per day before the meal, or included in the TMR (DU). Treatment RL led to lower DM intake and milk yield, but higher milk production efficiency; there were no significant differences between treatments RM and RH. There were no significant treatment effects on DM intake, milk yield, or milk composition in Exp. 2. Manipulating rumen synchrony by altering the timing of feeding affected milk yields, with D1 cows producing significantly less than D2 and DU cows, which were similar. The amount of ERDP in the diet should be matched to the amount of fermentable energy available to maximize intake, milk yields, and the conversion of feed N into milk protein. However, this study showed only small benefits to altering the diurnal pattern of supply of RDP and FME, and only with extreme feeding strategies that would not be used in practice. Urine volume increased in response to increased or unbalanced protein supply. Analysis of the allantoin:creatinine ratio in spot samples of urine was not useful in identifying predicted differences in microbial protein yield from the rumen.     

天铁动力6~#TRT静叶伺服控制系统改造

针对天铁动力6#高炉煤气余压发电机组(6#TRT)静叶伺服控制系统静叶不同步,造成机组连接板断裂事故,分析了其发生原因,通过改造液压系统和自控伺服系统,设定相关参数,消除了由于静叶不同步而引起的设备故障现象,提高了机组运行周期,提升了发电效率,取得了较好的经济效益。     

基于AMESim的深水连接器驱动环液压缸同步仿真

深水垂直套筒式连接器工作过程中最重要的环节是卡爪合拢锁紧密封件,而为了给密封件提供均匀分布的预紧力,3驱动环液压缸的同步运动尤显重要。为此,应用AMESim软件建立了3驱动环液压系统仿真模型,对深水垂直套筒式连接器驱动环3个液压缸进行同步仿真分析。分析结果表明,不同负载对系统同步有很明显的影响,且随着偏载差值的增大,系统同步误差增大,压力损失增大;分流集流阀对液压缸同步有明显的改善作用,消除了系统活塞杆的不稳定运动,控制了系统的流量及活塞杆的运动同步性,改善了系统的动态性能,有利于深水垂直套筒式连接器功能的实现。