汽车内部空气污染状况的研究

车厢内存有大量的有害物质,世界卫生组织已明确将车内空气污染与高血压、艾滋病等共同列为人类健康的10大威胁.本文就车内空气主要污染物的来源、车内空气污染物对人体的危害、车内空气污染的主要影响因素进行了系统的调查分析.并在此基础上提出了车内空气污染的解决措施.     

Seasonal Biomass Accumulation and Nutrient Uptake of Pea and Lentil on a Black Chernozem Soil in Saskatchewan

ABSTRACT

Close relationships usually exist among biomass accumulation, nutrient uptake, and seed yield during the growing season. Field experiments with pea (Pisum sativum L.) and lentil (Lens cultinaris L.) were conducted in 1998 and 1999 at Melfort, Saskatchewan, Canada, to determine relationships of biomass accumulation and nutrient uptake with days after emergence (DAE) or growing degree days (GDD). For both biomass accumulation and nutrient uptake, maximum rates and amounts increased with time at early growth stages and reached a maximum value at late growth stages. The R² values for cubic polynomial regressions were highly significant, indicating their suitability to estimate the progression of biomass accumulation and nutrient uptake as a function of days after emergence (DAE). Both pulse crops followed a similar pattern in biomass accumulation and nutrient uptake, which increased in the early growth stages and reached a maximum late in the growth cycle. Pulse crops usually reached their maximum biomass accumulation rate and amount at early to late bud formation (42–56 DAE or 390–577 GDD) and at medium pod formation to early seed filling (75–82 DAE or 848–858 GDD) growth stages, respectively. Maximum biomass accumulation rate was 175–215 kg ha^{? 1}d^?1 for pea and 109–140 kg ha^{? 1}d^{? 1} for lentil. Maximum nutrient uptake rate and amount usually occurred at branching to early bud formation (28–49 DAE or 206–498 GDD) and at the flowering to seed filling (66–85 DAE or 672–986 GDD) growth stages, respectively. Maximum uptake rate of nitrogen (N), phosphorus (P), potassium (K), and sulfur (S), respectively, was 4.6–4.9, 0.4–0.5, 5.0–5.3 and 0.3 kg ha^{? 1}d^{? 1} for pea, and 2.4–3.8, 0.2–0.3, 2.0–3.4 and 0.2 kg ha^{? 1}d^{? 1} for lentil. In general, maximum nutrient uptake rate and amount occurred earlier than maximum biomass accumulation rate and amount, respectively; and the maximum accumulation rates of both biomass and nutrients occurred earlier than maximum amounts. The findings suggest that adequate supply of nutrients from soil and fertilizers at early growth stages, and translocation of biomass and nutrients to seed at later growth stages are of great importance for high seed yield of pulse crops.     

不同吸附特性的稻草生物炭对稻田氨挥发和水稻产量的影响

秸秆生物炭具有改善土壤生态环境、土壤蓄水保肥和减少温室气体排放等正效应,但其石灰效应会加大稻田氨挥发损失.为充分发挥生物炭吸铵特性,降低其石灰效应的不利影响,对不同热解温度(300、500、700℃)和酸化水平(pH值=5、7、9)稻草生物炭处理下的田面水NH4+-N浓度、氨挥发和水稻产量进行了研究.结果表明:偏酸性(...     

基于木质素部分脱除及其含量对生物质热解特性的影响

该研究采用固定床热解炉,研究不同木质素含量花生壳、核桃壳样品的裂解行为,利用元素分析、工业分析、气相色谱-质谱联用以及气相色谱法对原料和热解产物进行分析,探究木质素与综纤维素在原始交联结构下的交互作用及其对热解产物分布特性影响。研究结果发现,300℃热解条件下,随着木质素含量的增加,样品中固体产率增加,液体产率和气体产率下降。500、700℃热解条件下,固体产率相比300℃有大幅度的下降,且随样品中木质素含量的增加,固体产率无明显变化,液体产率稍微增加,气体产率下降。500℃时,H2产率很低,随样品中木质素含量的增加,CO2含量减少,CH4含量增加,CO含量有稍微的上升。而700℃时,综纤维素的脱氢、缩合、成环会生成大量的H2。同时,木质素能够促进综纤维素分解生成大量左旋葡聚糖,并抑制其分解;而综纤维素抑制木质素单体愈创木基的脱甲氧基反应,促进苯丙烷基的脱烷基反应,形成更多的酚类化合物。该研究对于生物质组分间交互和产物形成特性研究具有积极意义。     

非洲猪瘟病原学检测技术研究进展

非洲猪瘟(African swine fever,ASF)是由非洲猪瘟病毒(African swine fever virus,ASFV)感染家猪和野猪而引起的一种急性烈性、高度接触性传染病,到目前为止仍未研制出有效疫苗,因此病原的早发现对ASF防控尤为重要.ASFV的病原学检测主要包括活病毒检测、核酸检测和抗原检测....     

小麦秆黑粉病持续控制技术研究

小麦秆黑粉病曾是中国北方麦区主要病害,近年病情回升、局部为害严重。为持续控制该病严重流行造成的毁灭性灾害,本研究采用品种抗病性鉴定和药剂多点试验结果多重比较的方法,从目前推广品种（系）资源207 份材料中,鉴选出高抗和中抗品种,‘晋麦31’、‘晋麦32’、‘晋麦33’、‘临优145’、‘临抗20’、‘运旱618’、‘运94-32’、‘豫麦57’、‘烟农19’、‘郑麦9023’、‘冀麦32’等11 个;利用3 地区不同生态条件多重复鉴定分析方法,试验出可替代五氯硝基苯的拌种药剂类型有三唑醇、粉锈宁、多菌灵、甲基硫菌灵、安克锰锌等5 种。研究结果证明,采用药剂拌种和选用抗病品种相结合的防治措施,可持续控制小麦秆黑粉病的流行为害。     

农用电动汽车动力系统参数匹配优化及动力性验证

根据纯电动汽车性能的设计指标,对农用电动汽车的电动机、电池组及传动比等动力系统参数进行了合理匹配与优化设计.采用区间优化方法对减速器速比进行了优化设计,在满足电动汽车动力性能要求的前提下,以设计变量的最大可行区间代替其传统的确定性最优值,解决了传动系统齿轮的配齿问题.由优化设计结果,使用ADVISOR软件对整车动力性能进行了仿真分析,并对仿真结果进行了实验验证.     

FSWM: A hybrid fuzzy-stochastic water-management model for agricultural sustainability under uncertainty

A hybrid fuzzy-stochastic water-management (FSWM) model is developed for agricultural sustainability under uncertainty, based on advancement of a multistage fuzzy-stochastic quadratic programming (MFSQP) approach. In MFSQP, uncertainties presented in terms of fuzziness and randomness can be incorporated within a multilayer scenario tree, such that revised decisions are permitted in each time period based on the realized values of the uncertain events. Moreover, fuzzy quadratic terms are used in the objective function to minimize the variation of satisfaction degrees among the constraints; it allows an increased flexibility in controlling the system risk in the optimization process. Results of the case study indicate that useful solutions for the planning of agricultural water management have been obtained. In the FSWM model, a number of policies for agricultural water supply are conducted. The results obtained can help decision makers to identify desired water-allocation schemes for agricultural sustainability under uncertainty, particularly when limited water resources are available for multiple competing users.     

基于超磁致伸缩转换器的流体控制阀及其技术

介绍了超磁致伸缩材料在流体控制阀中的应用研究现状，详细分析了使用GMA时要解决的热补偿、微位移放大和非线性控制等几项关键技术。提出了两种基于GMA的两级电液伺服阀实现方案。     

自由曲面数控加工中过切的小波分析

将小波分析方法应用于自由曲面数控加工中过切信号分析和处理,在给出小波分析概念的基础上,较为详细地讨论了离散二进正交小波算法－Ｍａｌｌａｔ算法。通过小波变换将原始信号分解到不同频带,进而观察到过切的特征。研究表明：多分辨（多尺度）分析的方法,对于数控加工中曲面过切这种故障信号不但具有精确的时－频定位作用,而且还具有易于监测的优点,是继ＦＦＴ之后信号处理的又一有力工具。