高产奶牛孕检后同期发情程序选择的研究

为了研究适用于高产奶牛的同期发情程序方案,将218头膘情良好、子宫和卵巢发育正常的不同胎次荷斯坦牛随机分成两组,试验1组为106头,试验2组为112头,分别采用两种同期程序(0.5.6.8和0.7.8.9)进行处理,测定情期受胎率,用于评价两种同期程序对高产奶牛的适用性.结果表明,试验2组情期受胎率平均为41.96％,...     

配气定时对柴油机性能优化的仿真分析

利用美国GAMMA公司开发的发动机仿真软件GT-POWER,建立16V280型柴油机的仿真模型,研究配气定时对该机型油耗和排放的影响。在标定转速下,对100%,75%,50%,25%负荷工况进行部分配气定时的优化,仿真分析出综合情况最优方案,为该机型的后续改进和优化提供参考。     

基于绿波控制的道路连续交叉口配时优化

基于现实路段中存在的信号配时不合理的现状,利用绿波控制的思想,结合道路实际情况,将相邻的3个交叉口作为一个系统,利用韦伯斯特配时方法统一优化配时,利用图解法确定合适的相位差,最终得到合理的配时方案。通过仿真软件模拟分析,比较优化前后主干道通行情况,验证了配时方案的优越性。     

苹果苗木类型和栽植时间对幼树生长特性的影响

【目的】为了研究不同栽植时间下不同苗木类型的生长特性,【方法】以3 a生‘长富2号’/‘M26’/八棱海棠为试材,测定3个栽植时间(2010年3月10日、4月10日和5月10日)下分枝苗、去分枝苗和单干苗生长特性相关指标。【结果】5月份栽植植株的生长势弱于3、4月栽植的植株;单干苗生长势弱于分枝苗和去分枝苗。栽植后第2年,3、4月栽植植株的株高、主干粗度显著大于5月栽植的植株。去分枝苗和单干苗株高显著大于分枝苗。3种苗木类型主干粗度依次为分枝苗>去分枝苗>单干苗,且相互差异显著。分枝苗和去分枝苗冠径显著大于单干苗。栽植后第3年,分枝苗的花芽数显著高于去分枝苗和单干苗。【结论】苹果苗木在冷藏条件下,4月栽植是可行的,本试验中3月份栽植较为适宜。分枝苗有利于促进幼树提早开花结果。     

基于 Synchro 与 VISSIM 混合仿真的单点交叉口信号配时优化方法研究

交通仿真是设计、分析和评价交通方案的重要技术方法。重点介绍微观交通仿真软件中的Synchro与VISSIM软件。选取上海市某单点交叉口，针对无法利用VISSIM软件对原有交叉口交通信号配时方案进行优化的缺点，先利用Synchro中的信号配时优化功能对交叉口信号配时进行优化，然后再对交叉口进行交通仿真评价。仿真结果表明，利用Synchro对交叉口信号配时进行优化后，交叉口运行效率好于未进行信号配时优化时的运行效率，此方法具有较好的工程实用性与推广意义。     

螺旋气道变截面进气的缸内充量分层模拟研究

构建了YN33共轨柴油机螺旋气道-气门-气缸的CAD模型,划分螺旋气道的进气口为不同进气截面,并通过在各个截面分区进气,以及时序分区进气实现缸内的充量分层。研究表明:变截面进气时,进气截面下半部进气量比上半部进气量多7%,而右下区的进气会在缸内形成较为均匀的分布,其它区域进气则会形成浓度场各异的分布特性。三段时序进气条件下,4个区域进气对缸内进气总量贡献的差异由前段进气与后段进气所决定,且后段进气影响更大;在分布特性上,进气截面右上区和右下区的前段进气会在缸内形成明显的上稀、下浓分布特点,而后段进气均会在缸内形成上浓、下稀的分布。     

Diel timing of molting and metamorphosis of Panulirus japonicus phyllosoma larvae under laboratory conditions

ABSTRACT:   The timing of molting and metamorphosis was monitored for Panulirus japonicus phyllosoma larvae cultured in the laboratory. Larvae cultured under natural light–dark cycle molted synchronously within approximately 1.0 h before and after sunrise, except for a short period after hatching; the timing of molting changed with time of sunrise. When three artificial light–dark cycles were introduced, larvae molted around the start of lighting, irrespective of the light–dark cycles. In the event of a sudden change in the start or end of lighting, molting was regulated by an endogenous rhythm. The start of lighting had a greater impact on the timing of molting than the end of lighting, suggesting that sunrise is probably the critical signal for phase-setting in molting rhythm. Metamorphosis to the puerulus stage occurred within 0.4 h before and 1.2 h after sunset under a natural light–dark cycle, and the timing of metamorphosis was also changed artificially by regulating the end of lighting.     

From a sequential pattern,temporal adjustments emerge in hummingbird traplining

Animals that feed from resources that are constant in space and that refill may benefit from repeating the order in which they visit locations. This is a behavior known as traplining, a spatial phenomenon. Hummingbirds, like other central‐place foragers, use short traplines when moving between several rewarding sites. Here we investigated whether traplining hummingbirds also use relevant temporal information when choosing which flowers to visit. Wild rufous hummingbirds that were allowed to visit 3 artificial flower patches in which flowers were refilled 20 min after they had been depleted repeated the order in which they visited the 3 patches. Although they tended to visit the first 2 patches sooner than 20 min, they visited the third patch at approximately 20‐min intervals. The time between visits to the patches increased across the experiment, suggesting that the birds learned to wait longer before visiting a patch. The birds appeared to couple the sequential pattern of a trapline with temporal regularity, to some degree. This suggests that there is a temporal component to the repeated spatial movements flown by foraging wild hummingbirds.     

Mycoflora and Mycotoxicological Quality of Four Freshly Harvested Paddy Rice Cultivars and Relation with Harvest to Industry Reception Timing

Grain quality and safety of four freshly harvested paddy rice (Oryza sativa L.) cultivars (Epagri 109,SCS 114 Andosan,Tio Taka 113 and Epagri 115 CL) grown under irrigation system in the north of Santa Catarina State,Brazil were studied.The quality parameters evaluated were mycoflora,mycotoxins (aflatoxins,ochratoxin A and zearalenone),water distribution (moisture content and water activity) apart from environmental conditions (relative humidity and temperature) and the relation between harvest and the industry reception timing.All cultivars presented an average waiting time of 8.6 h (ranged from 0.3 to 24.9 h),a total fungi load of 8.6×104 cfu/mL (ranged from 1.8×103 to 9.4×105 cfu/mL) with a rather high humidity condition of 19.0% moisture content (varied from 14.9% to 24.5%) and 0.92 water activity (varied from 0.78 to 0.99) under the average environmental conditions of 87.3% relative humidity (varied from 80.0% to 96.8%) and 25.4 ℃ (varied from 22.5 to 27.5 ℃),respectively.The conditions to which the samples were submitted allowed fungal growth,but no mycotoxins were detected.Regarding the rice cultivars fungal genera isolated,Aspergillus and Penicillium were the most often isolated among all the cultivars and variation on fungi distribution among them was not observed.Moreover,it was not found a correlation of the grain loading & unloading time with the humidity conditions and the total fungi load.Furthermore,all results and the importance of monitoring the rice mycotoxicological quality and safety were discussed.     

发动机可变配气相位的研究

目前,人们不断挖掘发动机自身的潜力,使其朝着电控和变参数方向发展.而可变配气相位技术由于对提高发动机的动力性和经济性效果显著,并且在一定程度上能够改善有害排放,一直受到人们的关注.为此,对采用优化进气门迟闭角的发动机重新进行了模拟计算.结果表明,在发动机上实施进气门迟闭角滞后10°CA时,最大功率由84.4kW提高到了87.3kW,增加了3.6%,高速区功率和转矩平均提高了3%～7%,转矩曲线趋于平坦,燃油经济性也有较大的改善.