切纵流联合收获机小麦喂入量预测的试验研究

为及时获知切纵流联合收获机在田间收获时的喂入量,该文将切纵流联合收获机的切纵流脱粒分离装置在室内建成切纵流脱粒分离试验台并进行喂入量为1～8kg/s的小麦脱分性能试验,通过采集切流滚筒,喂入轮和纵轴流滚筒的脱分功耗,对切纵流脱粒分离装置脱分功耗进行分析,推导出喂入量与纵轴流滚筒净脱分功耗之间的关系,并用采集小麦随机喂入量脱分功耗的方法对切纵流脱粒分离试验装置的喂入量进行预测验证。结果表明,利用纵轴流滚筒净脱分功耗可以较准确的预测切纵流联合收获机在小麦收获中的喂入量,在喂入量≤6kg/s时,预测误差≤0.89%;喂入量在7～8kg/s时,预测误差在1.02%～1.42%之间。     

Evaluation of dietary creatine and guanidinoacetic acid supplementation in juvenile red drum Sciaenops ocellatus

Two separate comparative feeding trials were conducted to evaluate if supplemental dietary guanidinoacetic acid (GDA), either singly or in combination with creatine, could enhance growth performance of red drum. The basal diet for both trials was formulated with practical ingredients but was not supplemented with creatine or GDA. For the experimental diets, creatine (0 or 20 g/kg) and GDA (0, 5 or 10 g/kg) were added to the basal diet in a 2 × 3 factorial arrangement for trial 1. Another 2 × 3 experimental design was adopted in trial 2 to further evaluate creatine (0 or 20 g/kg) and GDA (0, 10 or 20 g/kg) supplementation. Each diet was fed to juvenile red drum in either quadruplicate (trial 1) or triplicate (trial 2) aquaria twice daily for a total of 8 weeks. After each feeding trial, fish were sampled for body condition indices and whole‐body composition analysis, as well as determination of plasma, liver and muscle creatine concentrations. In trial 1, dietary creatine supplementation alone significantly (p < .05) improved weight gain and feed efficiency of red drum. An interaction between creatine and GDA was seen in whole‐body protein and lipid in the two trials. In trial 1, the highest levels of whole‐body protein and lipid were observed in fish fed 10 g GDA/kg, and in trial 2, supplementation of the diet with 10 g GDA/kg increased muscle protein and muscle lipid although there was a trending decline in fish fed the 20 g/kg GDA‐supplemented diet. In both trials of the present study, dietary GDA significantly (p < .05) enhanced liver creatine content. Dietary creatine also significantly (p < .05) enhanced plasma and muscle creatine content of red drum. Based on the results of this study, creatine was effective in enhancing weight gain and feed efficiency of red drum as seen in previous studies; however, GDA was not effective in influencing growth performance but limited synthesis of creatine from dietary GDA was apparent.     

轴流螺旋滚筒式食用向日葵脱粒装置设计与试验

针对食葵脱粒过程中籽粒表皮划伤严重及未脱净率高等问题,该研究设计了一种轴流螺旋滚筒式食葵脱粒装置。脱粒元件为外径32 mm的螺旋管,对物料在脱粒空间的运移过程进行运动学与动力学分析,确定脱粒元件螺旋管螺旋升角为63°,螺距为2 800 mm。以葵花3638为对象进行台架试验,通过单因素试验探索喂入量、滚筒转速及脱粒间隙对籽粒未脱净率和破损率的影响,根据单因素试验结果,以喂入量、滚筒转速、脱粒间隙为影响因素,未脱净率和破损率为响应指标,进行二次回归正交旋转组合试验,利用Design-Expert软件建立响应指标与影响因素之间的数学模型,基于响应面法进行参数优化,获得脱粒装置在喂入量1.4 kg/s,滚筒转速300 r/min,脱粒间隙35 mm的参数组合下脱粒效果较好,此时未脱净率为0.55%,破损率1.76%。以优化参数组合进行验证试验,结果表明,未脱净率为0.59%、破损率为1.77%,与模型预测值的相对误差均小于5%。该装置未脱净率与破损率均低于现有向日葵脱粒机,满足向日葵机械化收获标准。该研究为食葵机械化收获装备的研制提供理论参考。     

鮸鱼亲鱼培育及其人工繁殖的研究

采用自然苗培育成的1龄鱼,通过“春肥、夏育、秋繁、冬保”8字方针培育成亲鱼,性成熟率达到95%。经LHRH-A30.8~1.8μg/kg催产并放人产卵池自行产卵,获产率达到96.83%。获受精卵650万余粒,受精率达到52%。受精后21.8 h孵化出鱼苗,孵化率达到70%。     

Ontogeny of pancreatic enzymes in larval red drum Sciaenops ocellatus

The growth, survival and trypsin, lipase and amylase activities of red drum larvae were measured in two experiments. For the first trial, a group was fed live prey only (L) and another group was fed a combination of a microparticulate diet (MPD) and live food (L-MP). For the second growth trial a group fed the MPD only (MP) and a starvation group (ST) were examined in addition to the L and L-MP treatments. Enzyme activities of live prey were measured to estimate their possible contribution to larval digestion. No significant ( P  > 0.05) differences in final size and survival were observed between treatments L and L-MP. Larvae subjected to starvation or fed the MPD diet alone were smaller than treatments fed live prey and did not survive past days 5 and 14, respectively. Trypsin, lipase and amylase activities were detectable at hatching. No significant differences ( P  > 0.05) in total enzyme activities among treatments were observed before day 14. Specific activity of trypsin, lipase and amylase peaked on day 3 (prior to first feeding) and subsequently decreased. For trypsin, the percentage of enzyme activity potentially attributable to ingested prey increased with age to a maximum of 17%. For lipase and amylase this fraction was less than 5% throughout the study, except on day 8 (12% and 24%, respectively). The lack of significant differences observed in the activity of digestive enzymes among treatments suggests that dietary regime, availability of prey and possible effects of exogenous enzymes did not significantly influence enzyme activity. Therefore, the lower growth rate observed in the L-MP, MP and starved treatments cannot be attributed to low digestive enzyme production of the enzymes measured. It is more likely that the MPD failed to supply the required nutrients for adequate development.     

果园套种模式下花生摘果装置设计与试验

针对新疆果园套种花生的种植模式在收获花生过程中行走不便、荚果破碎率高、生产率低等问题,研制了一种果园套种模式下花生摘果装置.在分析整机工作原理的基础上,进行了关键零部件的设计及参数确定.确定摘果滚筒转速X1、喂入口倾角X2和摘果间隙X3三个因素为影响摘果效率的主要因素,并对摘净率和破碎率进行试验研究.试验结果表明:影响...     

Site fidelity and movement patterns of wild subadult red drum, Sciaenops ocellatus (Linnaeus), within a salt marsh-dominated estuarine landscape

Abstract  During summer and autumn 2002, 12 subadult red drum, Sciaenops ocellatus (Linnaeus) (261–385 mm total length) were surgically implanted with ultrasonic transmitters and released within the upper reach of the Duplin River Estuary, Sapelo Island, GA, USA. A fixed array of submerged receivers automatically recorded the time that individual tagged fish were detected at 10 sites within the study area. Ten red drum implanted with transmitters were located within the receiver array for 6–96 days post-release. All fish exhibited a high degree of site fidelity at low tide, and movements appeared to be influenced by both tidal and diel cycles. Dispersal on flood tides was observed, but destinations (upriver or downriver) and paths taken (main channel, intertidal channels or flooded marsh surface) varied among individuals. Flood-tide movements were generally restricted to daylight hours. If the start of flood tide occurred after sunset, fish remained stationary. Variation in details of movement patterns among individuals notwithstanding, predictable behaviour and strong site fidelity make subadult red drum vulnerable to recreational fishing in the restricted tidal channels of the tidal marsh–estuary complex. However, the same predictability provides fisheries managers a means of targeting specific areas for protection of over-fished populations of this species.     

轴流弓齿式食葵脱粒装置设计与试验

针对现今食葵脱粒过程中普遍存在的脱粒不完全和籽粒易受损等问题,设计一种针对食葵收获机脱粒的轴流弓齿式食葵脱粒装置,并对葵盘在脱粒装置中的受力情况进行分析。借助离散元仿真软件EDEM对食葵盘在滚筒内部的轴向速度、轴向位移以及运动路径进行分析。通过单因素试验获得了含水率、滚筒转速以及喂入量等因素对籽粒破损率及未脱净率的影响规律。根据单因素试验结果,以含水率、滚筒转速以及喂入量作为试验因素,以食葵未脱净率和破损率作为评价指标进行正交试验,利用Design expert对试验结果进行了方差分析,建立了影响因素与评价指标的回归模型,明确了各因素对滚筒实际工作效果的影响程度。基于响应曲面法,以低破损率和未脱净率为目标,对含水率、滚筒转速以及喂入量进行多目标寻优求解,得到最佳作业参数组合,即含水率22%、喂入量1.45 kg·s^-1、滚筒转速318 r·min^-1。为了确保参数组合的可靠性,对最佳参数组合进行验证试验,结果显示,籽粒未脱净率0.51%、破损率0.67%,满足我国机械行业标准。     

滚筒式营养钵体制钵机研究设计

针对目前市场上冲压式、螺旋式等种类制钵机生产率低、整机结构复杂等问题,利用两个凸轮的动静结合,首次采用滚筒的方式研究设计了一种新型连续式营养钵体制钵机。该机具能一次完成对营养钵的上料、打种孔、压实、投出等加工,效率高(10 800个/h),同时营养钵的尺寸、形状和强度等方面都满足高速机械化移栽的要求,可广泛适用于棉花、玉米、瓜果、花卉等作物所需营养钵的制作。     

黄河泥沙碟式分离机转鼓有限元分析

针对黄河泥沙碟式分离机结构设计,分析了转鼓壁离心应力产生的原因;利用ANSYS软件对分离机转鼓结构进行动力学建模和有限元分析,以满足转鼓强度、刚度使用要求,为分离机转鼓结构改进提供了理论和技术依据.