新型无轴承无刷直流电动机结构与模型研究

目前研究的无轴承电机均是将电机和转子悬浮磁路合为一体,两个磁场的叠加一方面容易造成磁饱和,使电机的承载能力下降,影响电机的稳定悬浮;另一方面电磁转矩与径向悬浮力之间具有很强的非线性耦合,而实现解耦控制是非常复杂的。将无刷直流电机的优点与磁悬浮轴承的优点结合,提出一种六自由度可控的无轴承无刷直流电动机结构,通过研究其悬浮原理和运行原理,建立了转子偏心时的精确数学模型和PWM（脉宽调制）调速的精确数学模型,经仿真测试,表明了这种电机结构的合理性。主要特点是承载能力高且电磁转矩控制与径向悬浮力的控制相互独立,无需复杂的非线性解耦控制。     

Broom snakeweed (Gutierrezia sarothrae) Population Change in Central New Mexico: Implications for Management and Control

This paper examines changes in broom snakeweed populations (Gutierrezia sarothrae [Pursh] Britt. & Rusby) from 1979 to 2014 at three prairie grassland sites in New Mexico. Data gathered each fall were used to study broom snakeweed population dynamics and to estimate the probability that the relatively short-lived subshrub will die off or invade blue grama (Bouteloua gracilis [H.B.K. Lag]) rangelands. Annual broom snakeweed standing crop data were used to categorize populations as None (< 100 kg ha^? 1), Light (< 300), Moderate (< 750), or Heavy (≥ 750). Ordered logit regression was then used to estimate the frequency of transition between these categories over time depending on environmental and site factors. Significant variables found to influence annual variation in broom snakeweed included the broom snakeweed standing crop and density observed the previous period (+ effect for continued broom snakeweed); grass standing crop the previous period (?); rainfall received from April to June (+); and average temperatures during April (+) and June (?). The probability of broom snakeweed invading an area that is currently without the plant ranges from about 1% to > 40% depending on environmental conditions and the amount of grass standing crop present. Transition probability estimates were also used in a Monte Carlo simulation model to evaluate the economics of broom snakeweed control. The economics of chemical broom snakeweed control were most strongly related to the rate of snakeweed reinvasion on treated areas and to the probability of natural die-off if infested areas were not sprayed.     

条状刷式砂光机法向压力的测量与分析

为了研究条状刷式砂光机用于木制品异形部件砂光时,法向压力的变化规律,在不同理论接触长度、砂光条长度、砂光条偏转角度等条件下,对水曲柳试件进行砂光处理并测量法向压力.结果表明,砂光条施加到试件上的法向压力,随着理论接触长度、偏转角度的增大而增大,随着砂光条长度的增大而减小.用于异形面砂光时,适当增加砂光条的长度,可减小凹凸平面间法向压力的差值,增强条状刷式砂光机的形状适应性.     

利用“微创刷”法获得抗草甘膦转基因大豆

以发芽3 d的大豆成熟种子胚尖生长点为作用点,利用"微创刷"法将抗草甘膦基因(EPSPS)转入绥农22中,对转化植株T1代进行草甘膦筛选,对筛选后的抗性植株进行PCR检测,得到抗草甘膦转基因大豆。同时研究了不同浓度草甘膦对野生型绥农22与抗草甘膦转基因绥农22大豆植株的影响。结果表明:绥农22 T0代成株率为97.38%,对T1代具有草甘膦抗性的植株进行PCR检测,初步证明EPSPS基因成功转入大豆中,T1代转化效率为6.20%;对野生型绥农22与"微创刷"法获得的转基因绥农22大豆在不同浓度草甘膦进行相关生理指标测定,抗草甘膦转基因绥农22大豆在不同浓度草甘膦作用下叶片叶绿素含量指数、光合速率高于野生型绥农22大豆,莽草酸含量低于野生型绥农22大豆,进一步证明了大豆抗性植株对草甘膦的抗性。     

Fe-B合金化学沉积的影响因素分析

通过化学沉积法制备Fe-B化学镀层,用电化学方法分析了偶接铝、镀液组分和沉积工艺对Fe-B化学沉积行为的影响.结果表明,偶接铝使体系的沉积电位负移,降低了Fe-B合金化学沉积的极化阻力,特别是金属离子还原的极化阻力,从而诱导Fe-B的化学沉积.镀层的沉积速率依赖于镀液组分和沉积工艺.     

化学镀Fe-Al-P合金初探

利用化学镀方法在铜基片上施镀了Ｆｅ－Ａｌ－Ｐ合金镀层。通过改变金属盐比率ＡｌＣｌ３／（ＡｌＣｌ３＋ＦｅＳＯ４）、金属盐ＡｌＣｌ３和还原剂ＮａＨ２ＰＯ２的浓度等参数，研究了合金镀层的沉积速率，成分，表面形貌及结构的变化规律，得到了最佳镀液配方，发现络合剂和还原剂的选择是提高镀层含Ａｌ量的关键。     

新型温室除雪机在农业温室中的应用研究

冬季北方地区温室屋面除雪是农业部门研究的热点问题之一,为解决屋面积雪压塌温室这一问题,设计了一种新型温室除雪机,并对其除雪机构、输送机构及功率消耗进行了理论计算和试验验证。研究表明:采用硬质毛刷和螺旋机构制成的除雪机,适合清扫屋面的较厚积雪,减小了除雪过程中的阻力,降低了农民的劳动强度。理论分析和样机试验较吻合。试验表明,整机结构合理,具有很好的除雪效果,达到了预期设计目标。     

无电解电镀法制备具有电磁屏蔽功能的木材-金属复合材料(英文)

利用无电解电镀的方法制备了导电且具有电磁屏蔽功能的木材-金属复合材料。探讨了镀液用量、施镀时间和施镀温度对复合材料的表面电阻率和电磁屏蔽效能的影响,同时利用能谱分析(EDS)、X射线衍射分析(XRD)和扫描电镜分析(SEM)方法分别测定了不同施镀温度下得到的各镀层的磷含量、微结构和表面形貌。实验结果表明,在镀液使用量为500mL,施镀时间为30min和施镀温度为62℃的最优条件下,所得镀层的导电性和电磁屏蔽效果最佳。而且发现,随着施镀温度的提高,镀层中磷含量缓慢增加。XRD分析表明不同温度所得各镀层的结构均为多晶结构,通过SEM分析,镀层均匀、连续且具有金属光泽,说明在pH值一定的条件下,施镀温度对镀层结构和表面相貌的影响很小。     

吉林省主要造林树种、引种现状调查

针对去年冬季我省遇到几十年罕见的极端低温，造成部分树种发生冻害现象，另外有的单位或个人盲目大量引进未经在我省试验成功的速生树种问题，我们在全省范围内展开调查。经调查、分析、评价，提出了我省西部平原区、中部低山丘陵区、东部高寒山区适宜发展的造林、绿化树种以及不适宜发展的树种。     

Effects of ruminal dosing of mechanical stimulating brush on digestibility and rumen fermentation status in Holstein steers fed low rice straw at different lengths

The objectives of the present study were to determine the effect of ruminal dosing of mechanical stimulating brush (Rumen faibu; RF) on digestibility and on rumen fermentation status in Holstein steers fed high concentrate and low rice straw. Eight steers (461 kg in average bodyweight) were used. Four steers were orally dosed three RF per head (RF‐dosing) and the other four were not dosed (non‐RF). All steers were fed enough concentrate and rice straw to gain 1.4 kg/day in bodyweight. Rice straw was cut 2 cm and 30 cm. The organic cell wall content of feeding diets was 17% in dry matter basis. Digestibility and nutritive value were not affected by RF dosing and length of rice straw. Ruminal pH was significantly lower in RF‐dosing group than in non‐RF group after feeding, and tended to be higher in long rice straw than in short rice straw throughout the day. There were no clear difference on total volatile fatty acid concentration and molar proportion of volatile fatty acid by RF dosing and length of rice straw throughout examined period. These present results suggest that digestibility and rumen fermentation status are not affected by RF dosing when organic cell wall content of feeding diets is approximately 17% in dry matter with rice straw over 2 cm.