基于AMESim的液粘调速离合器动态接合特性研究

为了在不增加系统装机功率的前提下提升驱动扭矩,设计了一种"电机+飞轮+液粘调速离合器"驱动系统。创建了驱动系统各能量传递环节的数学模型、油膜承载力模型和驱动系统的AMESim仿真模型,揭示了飞轮转动惯量、油膜厚度控制曲线等因素对液粘调速离合器动态接合特性的影响规律,得到了扭矩、转速及冲击度变化曲线,搭建了相应的实验台架。仿真和实验结果表明,通过合理控制液粘调速离合器的油膜厚度,实现了持续时间长达50 s的两倍额定扭矩的输出,可满足大中型机械设备对于启动扭矩大、冲击度小的工程需求。     

休闲农业网设计开发及促进休闲农业产业的发展

中国休闲农业的健康发展,需要农业休闲产品与目标消费群体之间实现有效的供需对接。"互联网+"发展模式已经渗透到社会、生产和生活等的诸多方面,对旅游农业产业的发展起到了推动作用。该文以农业部创办的中国休闲农业网和去农庄网为例,分析了休闲农业网站的模块设计、栏目设置、内容浏览次数等,考察这2个网站的实际建设成效,并提出相应的网站建设建议,探索如何使用互联网技术更好地推动中国休闲农业与乡村旅游的发展。     

大体积混凝土BIM智能温控系统的研究与应用

回顾并分析了2015年我国蒜薹产业的经营情况,预测2016年全国蒜薹产业的前景,并提出蒜薹产业新时期面临的新挑战,旨在为稳健科学地应对2016年我国蒜薹产业的发展提供有益的参考借鉴。     

Maize yield improvements in China: past trends and future directions

Maize is one of China's most important grain crops. We analysed data from breeding trials and experimental reports to assess genetic gains in the single‐cross varieties in terms of grain yield and agronomic traits in Northern China, Southwestern China and Yellow–Huai River Valley. Since the 1960s, the grain yield of single‐cross varieties has increased linearly in all three regions. Plant height, ear rows and 100‐seed weight have increased linearly (P < 0.05) with time, while ear length has decreased (P < 0.05). Planting density has increased (P < 0.05) in Yellow–Huai River Valley and Northern China, but no change in Southwestern China. Ear height and leaf number in Northern China and Southwestern China have increased linearly (P < 0.05) over time, but no change in Yellow–Huai River Valley. The growing period in Yellow–Huai River Valley has increased linearly (P < 0.05), while that of Northern China and Southwestern China has not changed. Our analysis showed that contribution of agronomic traits to grain yield differed between agroecological regions. Future research and breeding strategies should focus on specific agroecological regions.     

饲喂乳酸菌和茶多酚对肉鸡生长及生理生化的影响

试验旨在研究乳酸菌、茶多酚对肉鸡生长性能、血液生化指标及肠道微生物的影响。选取1日龄AA肉仔鸡480羽,随机分成8组,每组60羽,设6个重复,每个重复10羽,在饲喂基础日粮的前提下,试验组灌胃乳酸菌和茶多酚,对照组灌胃无菌水,试验期为56天。结果表明：1.0 [mL∕(kg.bw)]乳酸菌＋0.06 [g∕(kg.bw)]茶多酚组的肉鸡末体重最高、平均日增重最快、平均日采食量最少、料重比最小;各试验组均降低了肉鸡的LDL（低密度脂蛋白胆固醇）、GLU（血糖）、TG（甘油三酯）、CHO（总胆固醇）、HDL（高密度脂蛋白胆固醇）的浓度,促进了乳酸菌、酵母菌等优势菌的生长,抑制了肠球菌的繁殖,为开发新产品、研究新的动物饲料添加剂提供了理论依据。     

液黏调速离合器离心式油腔设计及其特性

液黏调速离合器是一种依靠多油膜剪切力传递扭矩的装置,尤其适合于大型风机、水泵等工程机械调速节能.由于其各摩擦副润滑油入口处油压、流量大小无法保证均匀一致,在实际工程应用中往往出现摩擦副过热、变形、偏磨等问题.为了解决此类问题,提出了一种新型离心油腔式液黏调速离合器.理论分析表明:充分利用油腔离心力的甩油作用可使得润滑油均匀地甩入各摩擦副.另外,基于流体动力学理论,建立了2种不同结构的三维流场模型,应用Fluent对流场进行数值模拟计算,研究了油腔结构和普通油道结构对喷油孔处压力和流速的分布规律.仿真结果表明:离心式油腔的设计可显著提高液黏调速离合器各摩擦副润滑油入口处油压及流量的均匀性,从而提升液黏调速离合器的工作性能,延长其工作寿命.     

压缩机环状进气阀不同步特性的数值分析

为了研究环状进气阀各阀片的不同步特性,对往复式压缩机的膨胀-进气过程进行计算流体动力学的数值模拟以确定进行阀完整的运动规律.在压缩机内流场的瞬态计算过程中,通过在每一时间步内调用编写的关于活塞和阀片运动方程、阀片撞击判断条件、撞击时的位移约束和反弹速度边界的C语言程序,计算出4个阀片在各时间步内的位移增量,同时,运用动网格技术对计算网格进行更新,实现了对不同阀片运动过程的动态模拟.在分析网格无关性的基础上,研究了弹簧刚度和曲轴转速对各阀片的运动以及气阀实际进气量的影响.计算结果表明:阀片的不同步运动主要表现为阀片自内环到外环的逐渐关闭,随着弹簧刚度的增大和转速的降低,不同步现象越来越明显,当转速为300 r/min时,第1个阀片发生颤振,而刚度从4 000 N/m增大至6 000 N/m时,第1,2个阀片先后出现颤振,进气量约为阀片整体运动时的0.8倍,计算时必须考虑不同步对进气量的影响.     

寄主和非寄主植物对桑皱鞘叶甲取食行为的影响

为深入了解桑皱鞘叶甲Abirus fortunei （Baly）取食行为机制,探索安全有效的行为调控技术,通过观察其在寄主和非寄主植物上取食行为的差异,应用“Y”型嗅觉仪测试其对寄主和非寄主植物叶片气味的嗅觉行为反应,分析了寄主植物主要养分与其取食量之间的相关性。结果表明,桑皱鞘叶甲雌雄成虫在24 h内的取食选择率分别为70%和35%,其中70%以上叶甲偏向寄主植物桑树取食,对桑树嫩叶和老叶的平均取食量分别为0.21 g和0.19 g,二者无显著差异。桑皱鞘叶甲对寄主和非寄主植物叶片气味的嗅觉行为反应与对照差异不显著;其取食量与寄主植物叶片含水量、可溶性糖和蛋白质含量之间无明显相关关系。表明桑皱鞘叶甲的取食行为不受植物气味和主要营养物质的影响。     

Gene families encoding isoforms of two major sesame seed storage proteins, 11S globulin and 2S albumin

Sesame (Sesamum indicum L.) seed has been recognized as a nutritional protein source owing to its richness in methionine. Storage proteins have been implicated in allergenic responses to sesame consumption. Two abundant storage proteins, 11S globulin and 2S albumin, constitute 60-70 and 15-25% of total sesame proteins, respectively. Two gene families separately encoding four 11S globulin and three 2S albumin isoforms were identified in a database search of 3328 expressed sequence tag (EST) sequences from maturing sesame seeds. Full-length cDNA sequences derived from these two gene families were completed by PCR using a maturing sesame cDNA library as the template. The amino acid compositions of these deduced storage proteins revealed that the richness in methionine is attributed mainly to two 2S albumin isoforms and partly to one 11S globulin isoform. The presence of four 11S globulin and three 2S albumin isoforms resolved in SDS-PAGE was confirmed by MALDI-MS analyses. The abundance of these isoforms was in accord with the occurrence frequency of their EST sequences in the database. A comprehensive understanding of these storage proteins at the molecular level may also facilitate the identification of allergens in crude sesame products that have caused severe allergic reactions increasingly reported in the past decade.     

花龄对蓝莓柱头可授性及花粉活力的影响

以南高丛蓝莓"蓝雨"(Vaccinium australe)为试材,研究了花龄对柱头可授性和花粉活力的影响。结果表明,蓝雨蓝莓雌雄性器官的育性具有同步性。从花后第1～5天花粉活力都较高,特别是花后第2～4天,花粉活力保持在50%以上,是人工辅助授粉收集花粉的良好时期;花后第2～4天柱头分泌黏液较多,此期柱头具有较强可授性,是开展人工辅助授粉的最佳时期。