不同海拔下甲醇替代率和主喷正时对RCCI发动机性能的影响

为探究不同海拔条件下甲醇/柴油反应活性控制压燃（reactivity controlled compression ignition, RCCI）发动机的运行特性,该研究基于甲醇/柴油双燃料发动机试验台架,试验研究1 800r/min、100%负荷和3 200r/min、100%负荷下不同甲醇替代率、柴油喷射正时对发动机燃烧与排放性能的影响规律。结果表明：不同海拔条件下随着甲醇替代率的增加,缸压和瞬时放热率峰值逐渐升高,燃烧始点和燃烧中心前移,当量有效燃油消耗率（equivalent brake specific fuel consumption, ESFC）降低,有效热效率升高,NO_x和碳烟排放大幅降低,THC（total hydrocarbons）和CO排放增加。1 800 r/min、100%负荷工况下,甲醇替代率由0增至20%,0、1 000、2 000m海拔下最大缸压平均增加1.72MPa,瞬时放热率峰值平均升高25.08J/(°),ESFC平均降低4.67%,有效热效率平均升高4.90%,NO_x和碳烟排放分别平均降低16.63%和50%,THC和CO排放量分别平均增加142.03、388.18 mg/kg。3 200 r/min下甲醇替代率由0增至7%,不同海拔高度下ESFC平均降低1.76%,有效热效率平均升高1.79%,NO_x和碳烟排放量分别平均降低8.17%和20.70%。海拔高度由0升至2 000m,1 800r/min、20%甲醇替代率与3 200r/min、7%甲醇替代率下,瞬时放热率峰值分别降低4.80和8.08J/(°),燃烧中心分别推迟1.44°和1.43°,有效热效率分别降低0.82%和0.68%,ESFC分别升高2.10%和1.99%,NO_x排放量分别减少10.61%和7.35%,碳烟排放分别增加26.54%和32.12%,THC排放分别升高29.88%和15.45%,CO排放量分别增加22.42%和18.15%。固定甲醇替代率后,随着柴油主喷正时提前,不同海拔条件下缸压和放热率峰值逐渐升高,燃烧中心向上止点靠近,ESFC逐渐降低,有效热效率升高,碳烟排放减少,NO_x、THC和CO排放增加。1 800 r/min、15%甲醇替代率下,主喷正时从-1.5°提前至-7.5°,不同海拔高度下ESFC平均降低8.27%,有效热效率平均升高9.08%,碳烟排放平均减少90.94%。为提升高海拔条件下甲醇/柴油RCCI发动机的热效率和燃油经济性,可以适当增大柴油主喷正时。研究结果可为不同海拔环境下甲醇/柴油RCCI发动机燃烧与污染物排放控制优化提供参考。     

基于GIS的村级尺度统计数据空间化方法与时序分析初探

选择重庆市巴南区石龙镇大连村、大兴村、白马村、金星村、合路村、柏树村、大桥村、大园村和中伦村9个行政村作为研究区,将研究区的遥感影像、数字高程模型、行政界线等数据的空间参考坐标系统一为1980西安坐标系,选择2006-2012年研究区的农用肥施用量数据作为村级尺度统计数据空间化方法研究的研究数据,利用专家打分法对不同土地利用类型与农用肥施用之间的相关性进行打分,分值范围是0~1分。结合村级行政界线、行政村面积、农用肥施用量、土地利用数据和专家打分结果,构建农用肥施用数据空间化模型,分别生成2006-2012年村级农用肥施用数据空间化分布栅格数据,栅格尺度选择1、10、100和200 m这4种,并对栅格化结果进行对比分析。同时,对2006-2012年的农用肥施用空间分布数据进行时序分析,获取农用肥施用量的动态变化趋势。通过研究得到以下结论:1村级农用肥施用量数据空间化尺度与土地利用数据的类型及空间分辨率有关;2研究区各行政村农用肥施用量在2006-2012年期间总体变化趋于平稳。本研究对于实现村级统计数据空间化方法具有一定的参考意义,而空间化后的村级统计数据对于进行村镇区域规划、土地整改、生态环境保护等具有重要指导意义。     

Effects of iron injection timing on suckling and subsequent nursery and growing-finishing performance and hematological criteria

Two experiments were conducted to evaluate the effects of Fe injection timing after birth on suckling and subsequent nursery and growing-finishing pig performance. The injectable Fe source used in both experiments was GleptoForte (Ceva Animal Health, LLC., Lenexa, KS). GleptoForte contains gleptoferron which is a Fe macromolecule complex. In Exp. 1, a total of 324 newborn pigs (DNA 241 × 600, initially 1.6 ± 0.04 kg body weight [BW]) within 27 litters were used. Two days after birth, all piglets were weighed, and six barrows and six gilts per litter were allotted to 1 of 6 treatments consisting of no Fe injection or 200 mg of injectable Fe provided in a single injection on d 2, 4, 6, 8, or 10 of age. Pigs were weaned (~21 d of age) and allotted to nursery pens with all pigs in each pen having received the same Fe treatment. In Exp. 2, a total of 1,892 newborn pigs (PIC 359 × C40; initially 1.5 ± 0.02 kg BW) within 172 litters were used. One day after birth, piglets were weighed, and 11 pigs within each litter were allotted to 1 of 6 treatments consisting of no Fe injection or 200 mg of injectable Fe provided on d 1, 3, 5, or 7 of age, or 200 mg on d 1 plus 200 mg on d 12 of age. Pigs were weaned (19 d of age) and placed in a commercial wean-to-finish facility in a total of 15 pens with equal representation of treatments in each pen. In both experiments, not providing an Fe injection after birth decreased (P < 0.05) preweaning average daily gain (ADG), weaning weight, and hemoglobin and hematocrit values compared with all other treatments. In Exp. 1, increasing the age that piglets received an Fe injection until 4 or 6 d after birth provided marginal evidence for an improvement (quadratic; P = 0.070) in preweaning ADG. For the nursery period, increasing the age that piglets received an Fe injection improved (quadratic; P = 0.013) d 80 BW, but there was no evidence of a difference (P > 0.10) in d 173 BW at the end of the grow-finish period. In Exp. 2, increasing the age that piglets received a 200 mg Fe injection showed no evidence of difference (P > 0.10) for subsequent nursery and growing-finishing ADG. In both experiments, hemoglobin and hematocrit values were decreased (linear; P < 0.05) at weaning with increasing age when pigs received an Fe injection. These experiments suggest that providing a 200 mg Fe injection within 7 d after farrowing is sufficient for optimizing preweaning and subsequent growth performance.     

时序进气柴油机缸内分层与燃烧排放特征数值分析

缸内再循环废气(EGR)分布是发动机缸内EGR分层燃烧研究的重点与难点,由时序进气策略通过控制进气组分的充气时段来组织缸内EGR分层分布具有重要意义。以高压共轨重型柴油机为研究对象,采用CFD(Computation fluid dynamics)方法建立全参数数值仿真平台,研究不同时序进气组分经过进气及压缩过程后在缸内的分布特征及其对柴油机缸内燃烧及排放的影响。研究中以CO2代替EGR。研究结果表明,时序进气早期进气组分在气缸底部及燃烧室壁面附近分布较浓,后期进气则在气缸中心顶部分布较浓;时序进气能够获得显著的轴向分层分布;与均匀进气相比,缸内压力和温度偏低,燃烧滞后约0.7°CA,但放热率峰值偏高,NOx排放量降低51.2%,碳烟排放量降低13.4%。     

基于Visual C++MSComm通讯控件的排种器实验台变频调速系统设计

介绍了排种器试验台变频调速系统的系统组成,以及实现计算机与变频器之间串行通讯的硬件构成及程序设计方法, 以此实现了计算机与变频器的串行通讯。利用本系统可以满足排种器实验台对计算机控制的速度实时调节的要求。     

Effect of Harvest Timing on Yield and Mineral Nutritional Value of Kabuli Type Chickpea Seeds

Chickpea (Cicer arietinum L.) seeds are a good source of protein and mineral nutrients. However, there is no information regarding harvest timing on yield and mineral composition of chickpea seeds. The effect of harvest timing on seed yield, some yield components and mineral nutritional value of seeds of field grown chickpea plants in two different sites were studied. The mineral composition of chickpea straw depending on harvest timing was also evaluated in order to explain the variations of seed mineral concentrations in sink-source relationship manner. Yield and mineral nutritional value of chickpea were significantly affected by harvest timing. When compared to the seed yield at optimal harvest time, seed yield was 18% and 9% lower in the early harvest and 27% and 31% in the late harvest in Site 1 and Site 2, respectively. Late harvest of chickpea crops resulted in significant pod dropping and shattering. Generally, protein, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn), and manganese (Mn) concentrations of the seeds in optimal harvest were found to be greater than in early and late harvested plants. Harvest timing also results in significant variations in straw mineral nutrient concentrations of the plants. As the results of this study, it was concluded that the harvest timing is critical for yield losses and mineral nutritional value of chickpea seeds.     

基于窗口观测的电控柴油机判缸控制的优化分析

柴油机起动初期控制时序的建立过程(判缸控制)直接决定其起动过程的长短,判缸控制是电控柴油机管理系统中最核心的部分。为了缩短判缸时间,提高控制系统的可靠性,该文根据目标柴油机的发火顺序设计了电控系统的转速信号与相位,采用了2套转速计算装置;基于有限状态机,提出了窗口观测联合判缸方法,并开发了电子控制单元(electronic control unit,ECU)复杂驱动层的联合判缸驱动控制软件。试验结果表明该策略是有效可行的,发动机的起动成功率提升10%,达到100%,正常起动成功的时间由1.5 s缩短到1 s以内,改善了电控柴油机的起动性能。该控制策略的实现完善了电控柴油机的时序控制功能,提高了柴油机的电控水平。     

基于自适应深度学习的数控机床运行状态预测方法

针对机床状态动态标签及差异化分布数据下的预测适应性差与准确度低问题,结合时序特征关系和模型融合方法,建立自适应混合深度学习模型进行机床状态预测.首先,通过融合最小近邻分类器,设计一种基于权值累积的自适应更新法则,建立具有数据自适应性的状态预测模型.在此基础上,提出一种基于中心损失函数的特征距离度量优化策略,构建综合决策...     

进气道燃料喷射氢内燃机回火机理与控制研究

建立了包含进气道和气缸的氢内燃机三维仿真模型,研究了进气道燃料喷射氢内燃机不同转速和负荷条件下的回火机理.提出了通过优化喷氢相位,使低浓度混合气在进气门打开时首先进入气缸,降低缸内废气和热点温度,从而抑制回火的方法.仿真分析了不同转速和负荷条件下喷氢相位对进气门处混合气浓度和温度的影响,得到了最优的喷氢相位.经试验验证,优化的喷氢相位使氢内燃机能够在全工况内达到或超过混合气化学当量燃空比无回火工作.     

排种器实验台变频调速系统设计

为了利用排种器实验台进行精密播种机排种器的试验研究,设计了排种器实验台的调速系统.首先,介绍了排种器实验台变频调速系统的硬件构成;然后,基于计算机与变频器之间的串行通讯协议,利用VC 的MSComm通讯控件,用VC 6.0语言开发了排种器实验台变频调速系统的控制程序,实现了排种器实验台计算机与变频器的串行通讯.该系统具有操作方便、调速手段多、可靠性和抗干扰能力强等特点,可以满足排种器实验台需要对速度进行实时调节的要求.