注射模生产中智能化控制及应用

分析了注射模生产的现状，针对其生产中智能化调控应用方面的不足，提出模内参数的自适应调节方案，还介绍了自适应工作的原理、可调参数种类、逻辑推理等，并实际验证了基于注塑设备联网集成工艺数据下注射模成型工艺自适应调节的可行性。     

Assessment of chemical and microbiological parameters of indoor swimming pool atmosphere using multiple comparisons

The aim of this study was to evaluate the air quality of an indoor swimming pool, analyzing diurnal and seasonal variations in microbiological counts and chemical parameters. The results indicated that yeast and bacteria counts, as well as carbon dioxide (CO₂), nitrogen oxides (NO_x) and O₃ concentrations, showed significant diurnal difference. On the other hand, temperature, relative humidity (R.H.), yeast counts and concentrations of CO₂, particles, O₃, toluene, and benzene showed seasonal differences. In addition, the relationship between indoor and outdoor air and the degree of correlation between the different parameters have been calculated, suggesting that CO₂, fine particles and NO_x would have indoor origin due to the human activity and secondary reactions favored by the chemical and environmental conditions of the swimming pool; while O₃, benzene and toluene, would come from outside, mainly. The overall results indicated that indoor air quality (IAQ) in the swimming pool building was deficient by the high levels of CO₂ and microorganisms, low temperatures, and high R.H., because frequently the limits established by the legislation were exceeded. This fact could be due to the poor ventilation and the inadequate operation of heating, ventilation, and air‐conditioning systems.     

Research on the hot surface ignition of hydrogen‐air mixture under different influencing factors

To further reveal the pre‐ignition characteristics of hydrogen internal combustion engine, the effect of hot surface characteristic parameters on the ignition characteristics of hydrogen‐air mixture was investigated in this research. Based on the prototype of the constant volume combustion bomb with an overhead glow plug, the duration from the heating of the hot surface to the combustion of hydrogen‐air mixture, the so‐called heating duration, was firstly researched under different fuel‐air equivalence ratio, initial temperature, initial pressure, hot surface temperature, and hot surface area, and the influence of each factor on the heating duration was analyzed. The results show that the order of the effect of each factor on the hot surface ignition is as follows: hot surface temperature > initial pressure of hydrogen‐air mixture > equivalent ratio > initial temperature of hydrogen‐air mixture > hot surface area. The influence of the hot surface characteristic parameters on the heating duration was further analyzed in detail. On this basis, the relationship among the critical ignition temperature, the heating duration and the hot surface area was researched and established. The results show that the heating duration is the only major factor affecting the critical ignition temperature. Finally, the research results were applied to analysis the pre‐ignition in hydrogen internal combustion engine.     

Effects of feeding bentonite clay upon ochratoxin A–induced immunosuppression in broiler chicks

A presence of mycotoxins in feed is one of the most alarming issues in the poultry feed industry. Ochratoxins, produced by several Aspergillus and Penicillium species, are important mycotoxin regarding the health status of poultry birds. Ochratoxins are further classified into to several subtypes (A, B, C, etc) depending on their chemical structures, but ochratoxin A (OTA) is considered the most important and toxic. Bentonite clay, belonging to phyllosilicates and formed from weathering of volcanic ashes, has adsorbent ability for several mycotoxins. The present study was designed to study the effects of bentonite clay upon OTA-induced immunosuppression in broiler chicks. For this, 480 day-old broiler chicks were procured from a local hatchery and then different combinations of OTA (0.15, 0.3, or 1.0 mg/kg) and bentonite clay (5, 10, and 20 g/kg) were incorporated into their feed. At 13, 30, and 42 days of age, parameters such as antibody responses to sheep red blood cells, in situ lymphoproliferative responses to mitogen (PHA-P), and in situ phagocytic activity (i.e., via carbon clearance) were determined respectively. The results indicated there was a significant reduction of total antibody and immunoglobulin titres, lymphoproliferative responses, and phagocytic potential in OTA-treated birds, suggesting clear immunosuppression by OTA in birds in a dose-dependent manner. These results were also significantly lower in all combination groups (OTA with bentonite clay), suggesting few to no effects of feeding bentonite clay upon OTA- induced alterations in different immune parameters.     

工艺参数对尼龙6选择性激光烧结制件致密度的影响

针对高性能聚合物尼龙6材料的选择性激光烧结(SLS)工艺,研究了不同激光功率与扫描速度对成型件致密度的影响并进行了工艺优化。实验中激光功率10~50 W,扫描速度1 000~5 000 mm/s,其他工艺参数保持恒定。引入能量密度对激光功率与扫描速度的综合作用进行研究。结果表明:随着激光功率的增加或扫描速度的增大,制件的致密度呈现先增大后减小的趋势;随着能量密度的增加,制件的致密度呈现先增大后减小的趋势。在不同工艺参数下,获得制件的最大致密度为86.74%,此时激光功率为30 W,扫描速度为2 000mm/s,能量密度为0.043 J/mm^2。选定致密度为衡量指标,通过响应面回归分析模型建立了激光功率、扫描速度与致密度的优选工艺图谱,得到最优的工艺参数为激光功率45 W,扫描速度3 465 mm/s,此时预测的制件致密度为88.971%。     

运行参数对煤层气空化喷嘴性能的影响

针对传统提高煤层气采收率方法对煤层损伤较大等问题,根据水力空化射流产生空化波来改造储层、促进煤层瓦斯解吸,提高采收率的增产思路,采用混合多相流数值模拟方法,研究了煤层气增产的水力空化工具两个主要工艺参数(入口流速、出口围压)对其空化性能的影响,并通过进行室内实验的方式对模拟结果进行验证。结果表明:在入口流速达到40m/s之后增速趋于平缓,可视为最佳入口流速;同时随着围压的增大,空化能力降低,但可通过适当提高入口流速减弱围压提高带来的抑制效果。     

宽厚板连铸坯表面裂纹的产生原因及控制

针对近期包钢薄板坯连铸连轧厂宽厚板微合金钢铸坯出现的批量表面裂纹问题,通过考察表面缺陷类型,裂纹形貌特征,结合连铸工艺条件、钢水质量及设备状况,分析了板坯表面裂纹的主要原因,提出了优化振动参数,控制钢水氮含量,提高振动精度,调整保护渣性能以及提高二次冷却水水质等改善铸坯表面缺陷等措施,取得了比较明显的效果,其铸坯表面裂纹得到了有效控制。     

Genetic parameters of colostrum traits in Holstein dairy cows

The main objective of this study was to assess the genetic background of colostrum yield and quality traits after calving in Holstein dairy cows. The secondary objective was to investigate genetic and phenotypic correlations among laboratory-based and on-farm–measured colostrum traits. The study was conducted in 10 commercial dairy herds located in northern Greece. A total of 1,074 healthy Holstein cows with detailed pedigree information were examined from February 2015 to September 2016. All cows were clinically examined on the day of calving and scored for body condition. All 4 quarters were machine-milked, and a representative and composite colostrum sample was collected and examined. Colostrum total solids (TS) content was determined on-farm using a digital Brix refractometer. Colostrum fat, protein, and lactose contents were determined using an infrared milk analyzer, and energy content was calculated using National Research Council (2001) equations. Dry period length (for cows of parity ≥2), milk yield of previous 305-d lactation (for cows of parity ≥2), age at calving, parity number, season of calving, time interval between calving and first colostrum milking, and milk yield were recorded. Each trait (colostrum yield and quality traits) was analyzed with a univariate mixed model, including fixed effects of previously mentioned factors and the random animal additive genetic effect. All available pedigrees were included in the analysis, bringing the total animal number to 5,662. Estimates of (co)variance components were used to calculate heritability for each trait. Correlations among colostrum traits were estimated with bivariate analysis using the same model. Mean percentage (±SD) colostrum TS, fat, protein, and lactose contents were 25.8 ± 4.7, 6.4 ± 3.3, 17.8 ± 4.0, and 2.2 ± 0.7%, respectively; mean energy content was 1.35 ± 0.3 Mcal/kg and mean colostrum yield was 6.18 ± 3.77 kg. Heritability estimates for the above colostrum traits were 0.27, 0.21, 0.19, 0.15, 0.22, and 0.04, respectively. Several significant genetic and phenotypic correlations were derived. The genetic correlation of TS content measured on-farm with colostrum protein was practically unity, whereas the correlation with energy content was moderate (0.61). Fat content had no genetic correlation with TS content; their phenotypic correlation was positive and low. Colostrum yield was not correlated genetically with any of the other traits. In conclusion, colostrum quality traits are heritable and can be amended with genetic selection.     

Stability boundary analysis of magnetohydrodynamic circulator for the intermediate heat transfer system of prototype gen IV sodium fast reactor

One of the most important parts in the development of generation IV nuclear reactors is safety. In the research on generation IV sodium‐cooled fast reactors, magnetohydrodynamic (MHD) circulators have received attention for the stable transport of coolants. In this study, the stability of an MHD circulator was evaluated using a mathematical approach to obtain the critical value of the developed pressure. The critical developed pressure equation is a function of the flow rate and dimensionless parameters, which were derived from the theoretical model of the MHD circulator with a dimensionless scaled velocity, flow rate, and pressure. The stability conditions expressed using the critical value of the developed pressure and dimensionless parameters were investigated according to the changes in the main design variables of the MHD circulator. The relationships between the dimensionless parameters, stability, and main design variables constituting the stability boundary of the MHD circulator were analysed. The stability of the MHD circulator is considered safe when the stability criterion ε is lower than 1. The geometrical variables such as the duct thickness or width of the flow gap and electrical variables such as the frequency were the main parameters affecting the flow stability in the MHD circulator.