汽车转鼓试验台表面牵引力标定方法研究

为了确保转鼓试验台系统的精度,需要对其系统进行标定。标定的主要问题是如何对确定量进行测量,并通过何种调节手段,达到显示值与实际值之间的偏差符合精度要求的目的。汽车转鼓试验台转鼓主轴与转鼓电机主轴是重合的,转鼓通过电机主轴将其表面上牵引力传递给电机转子,依靠转子和定子的相互作用,牵引力将被传至与定子固定连接的电机外壳上。因此在电机外壳上安装测力传感器测量电机外壳切线方向上的力实现对转鼓试验台表面牵引力的测量。设计采用双向标定臂可以减小额外扭矩的影响,确保了汽车转鼓试验台表面牵引力的测试精度要求。     

RRR-α-Tocopheryl succinate is a less bioavailable source of vitamin E than all-rac-α-tocopheryl acetate for red drum, Sciaenops ocellatus

Bioavailability of the succinate ester of α-tocopherol has never been investigated with aquatic animals to date. Therefore, a 12-week feeding trial was conducted to compare bioavailability of α-tocopheryl acetate and α-tocopheryl succinate by slope ratio analysis. The semi-purified diets were supplemented with either 0 (basal), 10, 20 and 40 IU vitamin E/kg as all-rac-α-tocopheryl acetate or 10, 20, or 40 IU vitamin E/kg as RRR-α-tocopheryl succinate. Red drum juveniles were conditioned by feeding the basal diet for 8 weeks prior to the experimental period to reduce whole-body tocopherols. Fish initially averaging 12.2 ± 0.4 g/fish (mean ± SD) were fed experimental diets at a rate approaching apparent satiation for 12 weeks. Weight gain and feed efficiency responses of fish fed diets were not significantly altered by the type or level of vitamin E supplemented. However, α-tocopherol levels in liver and plasma were significantly (P < 0.01) influenced by dietary vitamin E level and ester form. The liver retention of α-tocopheryl acetate was 14 times higher than α-tocopheryl succinate, while thiobarbituric acid reactive substances (TBARS) in liver of fish fed α-tocopheryl acetate tended to be (P < 0.1) lower than that of fish fed α-tocopheryl succinate. In addition, plasma ascorbic acid in fish fed graded levels of α-tocopheryl acetate was significantly higher than fish fed graded levels of α-tocopheryl succinate. Fish fed the basal diet and 10 IU α-tocopheryl succinate/kg showed edema in the heart, while fish fed all other diets did not exhibit this pathology. Within the dose range of 0–40 IU/kg diet, hematocrit, neutrophil oxidative radical production and intracellular superoxide anion production of head kidney macrophages were not significantly influenced by α-tocopherol ester or dietary supplementation level. In conclusion, α-tocopheryl succinate is not readily available to juvenile red drum compared to the widely used α-tocopheryl acetate.     

转筒内D型二元颗粒物料滚落模式的径向分离

针对D型二元颗粒物料在转筒内的分离问题,以粘土颗粒和木制颗粒组成的物料为对象,采用离散单元法模拟了滚落运动模式下物料在转筒内的运动与分离过程。通过颗粒接触数定义物料混合指数,并结合Hong的渗流与凝聚竞争理论定量分析了物料的径向分离。结果表明:滚落运动模式下物料在转筒截面上分为平流层与活动层两部分,颗粒之间的分离运动发生在活动层;颗粒密度差异引起凝聚作用,使木制颗粒向转筒内壁分散而粘土颗粒向中心聚集,物料形成"月亮模式"分离形态;通过配置2种颗粒的半径可引入渗流机理,当渗流作用与凝聚作用相互平衡时,可避免物料发生径向分离;渗流机理的引入不受转筒尺寸的影响。     

集排式精量排种器清种装置设计与性能试验

为解决集排式玉米精量排种器低速作业重播严重的问题,设计了一种适用于滚筒式排种器的周向清种装置,对正压滚筒周向清种过程及种子运动过程进行了分析,建立了充种过程的运动学方程,结合种子占据比例的概念分析得出滚筒转速和型孔直径是影响清种效果的主要因素,确定了拨指长度20 mm和拨指末端倒角20°。在JPS-12型排种器性能检测试验台上以郑单958玉米种子为试验材料对集排式精量排种器清种装置的清种效果进行试验,以测试不同清种距离对重播指数和漏播指数的影响,清种距离优化试验表明:在0.25~2.25 mm范围内,清种距离对漏播指数没有显著的影响,但对重播指数、合格指数的影响高度显著。在清种距离大于0.25 mm时,漏播指数随清种距离的减小变化不明显,平均漏播指数0.16%,清种距离为-0.25 mm时,漏播指数急剧上升至5.83%;重播指数随清种距离的减小明显下降。确定优化后的清种距离为0.25 mm,对比试验表明,优化后的排种器在4~12 km/h的作业速度下合格指数均在96%以上,设计的清种装置可以有效降低集排气送式排种器低速作业时的重播指数。该文为进一步研究集排式精量排种器清种装置的结构设计和工作参数优化提供了依据。     

Inclusion of rendered animal ingredients as fishmeal substitutes in practical diets for cuneate drum, Nibea miichthioides (Chu, Lo et Wu)

Potential of using rendered animal ingredients, poultry by‐product meal (PM), meat and bone meal (MBM), feather meal (FM) and blood meal (BM) to replace fishmeal in practical diets for cuneate drum Nibea miichthioides (Chu, Lo et Wu) was examined in a net pen experiment. A total of 10 dietary treatments were compared. Nine diets were formulated to contain 363 g kg⁻¹ digestible protein and 14.8 MJ kg⁻¹ digestible energy, and a dietary treatment consisting of raw fish (RF) served as reference. In the formulated diets, the control diet contained 350 g kg⁻¹ herring meal, whereas in the other eight diets, the fishmeal were replaced by MBM (30% fishmeal replacement), PM (50% fishmeal replacement), a blend of PM, MBM, FM and BM (30%, 50% and 80% fishmeal replacement), or a blend of PM, MBM and BM (30%, 50% and 80% fishmeal replacement), respectively. Cuneate drum fingerling (initial body weight 28 g) were fed the test diets for 8 weeks. Specific growth rate (SGR), final body weight (FBW), nitrogen retention efficiency (NRE), condition factor and contents of moisture, crude protein and crude lipid in carcass were not significantly different between fish fed the formulated diets. Fish fed the formulated control diet exhibited lower SGR and FBW, but higher FCR, NRE, hepatosomatic index and crude lipid content in carcass and liver than those of the fish fed the RF. Results of the present study indicate that combination of rendered animal protein ingredients can replace most of the fishmeal in practical diets for cuneate drum.     

美国红鱼珠蛋白链的分离及其α-和β-珠蛋白基因的克隆

通过含Triton X～100的酸性聚丙烯酰胺电泳法从美国红鱼（Sciaenopes ocellatus）血液中分离到4条β-珠蛋白链和2条α-珠蛋白链，其中β1和β1链是主要β-珠蛋白链．α，链是主要α-珠蛋白链。美国红鱼α-珠蛋白基因cDNA开放读码框由435个核苷酸组成，编码144个氨基酸的多肽。与大黄鱼α-珠蛋白一样．美国红鱼α-珠蛋白在C与E螺旋间隔区也插入了一个独特的甘氨酸残基。美国红鱼β1-珠蛋白基因cDNA开放读码框由447个核苷酸组成，编码148个氨基酸的多肽。美国红鱼α-和β-珠蛋白基因拥有典型的珠蛋白基因结构，由3个外显子组成，中间间隔着2个内含子。美国红鱼β-珠蛋白基因内含子1有一段TTA重复序列，此序列插入可能使内含子原有的功能发生改变或丧失。     

泔水组份分选机的设计

泔水富含有丰富的营养成分且经固液分离后能生产有机饲料、有机复合肥以及各种皂类物质。由于固液分离在泔水处理工艺中十分重要,因而设计了泔水组份分选装置。该分选装置主要通过电机控制滚筒筛和螺旋输送器,实现固液分离,再经过抽屉式油水分离层进行油液分离,以达到绿色环保和节能的目的,在固液分离方面有一定的应用价值。     

立式转鼓水果分级机输送及翻转机构设计

设计了一种适应准球形水果自动单列输送和均匀翻滚的立式转鼓搓动鼓机构，其滚子节距保持不变；提出了搓动鼓不同转速与转向的3种运动形式；分析了3种不同运动形式的水果翻滚角速度误差与果径的关系、单果图像采集转鼓中心角与果径的关系、水果翻滚角速度误差与单果一周图像采集数量的关系；找出了搓动鼓与转鼓同向运动形式的最佳运动方案、不同转向下水果纯滚动的条件、满足水果图像采集条件的滚子锥角范围、分级过程中不掉果条件、不跳果条件和设备水果大小适应范围。     

低温速冻处理对美国红鱼-20℃冻藏生化特性的影响

以盐溶性蛋白质含量、巯基含量、ATPase活性、pH值、感观评定等为指标,研究美国红鱼在-20℃冻藏中肌肉蛋白质生化特性的变化情况。结果表明,无论是-20℃直接冻结还是-80℃低温速冻,在冻藏过程中随着时间的延长,美国红鱼的肌动球蛋白盐溶性、巯基含量以及ATPase活性均呈下降趋势;除冻藏后期外,低温速冻处理能降低美国红鱼蛋白质冷冻变性的程度。     

Essential fatty acid requirement of juvenile red drum (Sciaenops ocellatus)

Feeding experiments and laboratory analyses were conducted to establish the essential fatty acid (EFA) requirement of red drum (Sciaenops ocellatus). Juvenile red drum were maintained in aquaria containing brackish water (5 ± 2‰ total dissolved solids) for two 6-week experiments. Semipurified diets contained a total of 70% lipid consisting of different combinations of tristearin [predominantly 18:0] and the following fatty acid ethyl esters: oleate, linoleate, linolenate, and a mixture of highly unsaturated fatty acids (HUFA) containing approximately 60% eicosapentaenoate plus docosahexaenoate. EFA-deficient diets (containing only tristearin or oleate) rapidly reduced fish growth and feed efficiency, and increased mortality. Fin erosion and a “shock syndrome” also occurred in association with EFA deficiency. Of the diets containing fatty acid ethyl esters, those with 0.5–1% (n-3) HUFA (0.3–0.6% eicosapentaenoate plus docosahexaenoate) promoted the best growth, survival, and feed efficiency; however, the control diet containing 7% menhaden fish oil provided the best performance. Excess (n-3) HUFA suppressed fish weight gain; suppression became evident at 1.5% (n-3) HUFA, and was pronounced at 2.5%. Fatty acid compositions of whole-body, muscle and liver tissues from red drum fed the various diets generally reflected dietary fatty acids, but modifications of these patterns also were evident. Levels of saturated fatty acids appeared to be regulated independent of diet. In fish fed EFA-deficient diets (containing only tristearin or oleate), monoenes increased and (n-3) HUFA were preferentially conserved in polar lipid fractions. Eicosatrienoic acid [20:3(n-9)] was not elevated in EFA-deficient red drum, apparently due to their limited ability to transform fatty acids. Red drum exhibited some limited ability to elongate and desaturate linoleic acid [18:2(n-6)] and linolenic acid [18:3(n-3)]; however, metabolism of 18:3(n-3) did not generally result in increased tissue levels of (n-3) HUFA. Based on these responses, the red drum required approximately 0.5% (n-3) HUFA in the diet (approximately 7% of dietary lipid) for proper growth and health.