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针对示踪气体法测试回风立井型矿井外部漏风率过程中由于回风大巷的示踪气体采样检测有效长度有限可能会导致示踪气体无法准确采样检测的问题,以纳林河二号矿井一号回风立井和二号回风立井回风大巷为研究对象,制定了多回风巷型回风立井外部漏风率示踪气体法测试方案,在此基础上,分别采用理论公式法和CFD数值模拟方法计算了各回风大巷的SF6气体最短采样检测距离,理论公式法计算结果显示一号回风立井和二号回风立井均不宜采用示踪气体法测试矿井外部漏风率,CFD数值模拟方法计算结果与之相反。现场实测结果显示通过CFD数值模拟法确定的回风大巷最短采样检测距离处巷道断面内SF6气体分布均达到均匀分布状态,CFD数值模拟法计算结果的准确明显大于理论公式法,研究表明采用CFD数值模拟法计算示踪气体最短采样检测距离能够对回风立井型矿井外部漏风率示踪气体测试法的现场适用性进行科学准确地论证。 相似文献
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Wire arc additive manufacturing(WAAM)has been investigated to deposit large-scale metal parts due to its high deposition efficiency and low material cost.However,in the process of automatically manufacturing the high-quality metal parts by WAAM,several problems about the heat build-up,the deposit-path optimization,and the stability of the process parameters need to be well addressed.To overcome these issues,a new WAAM method based on the double electrode micro plasma arc welding(DE-MPAW)was designed.The circuit principles of different metal-transfer models in the DE-MPAW deposition process were analyzed theoretically.The effects between the parameters,wire feed rate and torch stand-off distance,in the process of WAAM were investigated experimentally.In addition,a real-time DE-MPAW control system was developed to optimize and stabilize the deposition process by self-adaptively changing the wire feed rate and torch stand-off distance.Finally,a series of tests were performed to evaluate the con-trol system's performance.The results show that the capability against interferences in the process of WAAM has been enhanced by this self-adaptive adjustment system.Further,the deposition paths about the metal part's layer heights in WAAM are simplified.Finally,the appearance of the WAAM-deposited metal layers is also improved with the use of the control system. 相似文献
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Local droplet sizes and volumes of entrained liquid are captured with an image-based measurement technique for comparison with a conventional, integral method for entrainment analysis. Experiments in a forced circulation flash evaporation were performed for different operating conditions and with two different chemical systems. Droplet size and frequency rise with an increase in thermal energy input. The local readings confirm the trends found by the integral measurement method. The modification of the image-based probe enables the detection of small (≈ 10 µm) and at the same time fast droplets under challenging operating conditions, such as vacuum and superheated feed similar to industrial process conditions. 相似文献
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为研究泵板装置对混流式水轮机上冠流道泄漏水影响,基于CFD商业软件平台,结合新疆红山嘴一级电站4号水轮机,以泵板装置为研究对象,将主轴密封真空度、泄漏量、上冠间隙进口与梳齿环出口压差作为3个研究指标。首先在模型准确基础上对泵板装置内泵叶角度和泵盖高度2个相关结构分别进行数值分析,其次对其联合优化结构数值模拟。研究表明,为提高主轴密封真空度将泵叶和泵盖联合优化可取得更佳效果,即泵叶斜置30°同时泵盖调节高度比在0.0272~0.1086之间,3个研究指标均可达到设计改造要求;上冠间隙泄漏量与泵叶及泵盖结构联系密切且泵盖高度比影响更明显。 相似文献
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《Journal of dairy science》2022,105(7):5954-5971
Residual feed intake (RFI) and feed saved (FS) are important feed efficiency traits that have been increasingly considered in genetic improvement programs. Future sustainability of these genetic evaluations will depend upon greater flexibility to accommodate sparsely recorded dry matter intake (DMI) records on many more cows, especially from commercial environments. Recent multiple-trait random regression (MTRR) modeling developments have facilitated days in milk (DIM)-specific inferences on RFI and FS, particularly in modeling the effect of change in metabolic body weight (MBW). The MTRR analyses, using daily data on the core traits of DMI, MBW, and milk energy (MilkE), were conducted separately for 2,532 primiparous and 2,379 multiparous US Holstein cows from 50 to 200 DIM. Estimated MTRR variance components were used to derive genetic RFI and FS and DIM-specific genetic partial regressions of DMI on MBW, MilkE, and change in MBW. Estimated daily heritabilities of RFI and FS varied across lactation for both primiparous (0.05–0.07 and 0.11–0.17, respectively) and multiparous (0.03–0.13 and 0.10–0.17, respectively) cows. Genetic correlations of RFI across DIM varied (>0.05) widely compared with FS (>0.54) within either parity class. Heritability estimates based on average lactation-wise measures were substantially larger than daily heritabilities, ranging from 0.17 to 0.25 for RFI and from 0.35 to 0.41 for FS. The partial genetic regression coefficients of DMI on MBW (0.11 to 0.16 kg/kg0.75 for primiparous and 0.12 to 0.14 kg/kg0.75 for multiparous cows) and of DMI on MilkE (0.45 to 0.68 kg/Mcal for primiparous and 0.36 to 0.61 kg/Mcal for multiparous cows) also varied across lactation. In spite of the computational challenges encountered with MTRR, the model potentially facilitates an efficient strategy for harnessing more data involving a wide variety of data recording scenarios for genetic evaluations on feed efficiency. 相似文献
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目的:研究旨在实验室环境条件下建立微生物饲料添加剂中枯草芽孢杆菌活性成分检测方法的评价体系并使用该方法进行测定。方法:本实验依据现行通用标准GB/T 26428—2010、JJF1059.1—2012和RB/T 151—2016,进行了微生物饲料添加剂中枯草芽孢杆菌中活性成分的菌落总数不确定度考察。结果:创建了微生物饲料添加剂中枯草芽孢杆菌活性成分的菌落总数不确定度研究方法,扩展不确定度U=4.59%(包含因子k=2),样品的范围在6.2×109~8.5×109cfu/g之间,符合误差允许范围。结论:建立了一种微生物饲料添加剂中枯草芽孢杆菌活性成分的菌落总数不确定度检测方法,通过不确定分量分析可以发现,实验室在进行枯草芽孢杆菌活菌计数试验过程中,主要影响因素顺序为:稀释>溶解>重复性>称量>移取。该方法适合于实验室内操作,可在不同实验室内进行推广应用。 相似文献