双螺杆挤压机的系统模型

本文指出了双螺杆挤压机系统的影响因素,从挤压系统的目标函数出发描绘了各因素与目标函数的相互影响过程,最后建立了一种双螺杆挤压机的系统模型     

基于BP算法的双螺杆挤压机系统数学模型的建立

本文以玉米、小麦的混合物料为原料,进行了双螺杆挤压机的螺杆转速、进料速度、供水速度、机筒温度四种操作参数对双螺杆挤压机的挤压膨化效果(以膨化度来衡量)的影响的研究。依据要因实验设计及实验数据建立了系统的BP神经网络模型,实现对过程参数控制和目标输出的预测,结果用于指导生产实践。     

单螺杆挤压机比能耗的参数优化及影响因素分析

本文作为螺杆食品挤压机生产率计算模型的一个应用, 以比能耗为目标函数, 对螺杆转速、机筒温度、物料湿含量进行了优化研究; 还就挤压机操作参数和几何参数对比能耗、生产率和物料温度的影响进行了分析     

单螺杆挤压机比能耗的参数优化及影响因素分析

本文作为螺杆食品挤压机生产率计算模型的一个应用,以比能耗为目标函数,对螺杆转速,机筒温度,物料湿含量进行了优化研究,还就挤压机操作参数和几何参数对比能耗,生产率和物料温度的影响进行了分析。     

挤压生产焦糖色素的研究--挤压机种类和有关结构参数对产品质量的影响

研究了直接以淀粉为原料挤压生产固体焦糖色素时，挤压机种类和有关结构参数对产品质量的影响。结果表明：双螺杆挤压机更适合于生产焦糖色素；螺杆元件理想的组合方式、增大螺杆长径比、减小模孔直径，可提高产品质量。     

操作参数对双螺杆挤压机挤压效果影响的研究

通过实验研究了荞麦、黑米、薏米三种谷物的混合物料为原料时,双螺杆挤压机的螺杆转速、物料湿度、机筒温度三种操作参数对双螺杆挤压机的挤压膨化效果（以糊化度衡量）的影响。依据可旋转中心组合实验设计及实验数据建立了相关的统计模型,通过对响应面和等高线的分析,得出了三种操作参数的最佳取值范围。本实验研究对于开发谷物膨化食品、探索双螺杆挤压机加工谷物原料的挤压机理具有重要的现实意义。     

双螺杆挤压机功耗的实验研究

本文研究了以荞麦、黑米、薏米三种谷物的混合物料为原料时,双螺杆挤压机的螺杆转速,物料湿度、机筒温度三种操作参数对双螺杆挤压机的功率消耗(以单耗衡量)的影响。依据可旋转中心组合实验设计及实验数据建立了相关的统计模型,通过对响应面和等高线的分析,得出了三种操作参数的最佳取值范围。本研究对于开发谷物膨化食品、探索双螺杆挤压机加工谷物原料的挤压机理具有重要的现实意义。     

螺杆挤压机及其应用研究现状

综述了螺杆挤压机挤压加工的原理以及单螺杆、双螺杆、三螺杆挤压机和超临界二氧化碳挤压膨化机几种挤压加工设备,并简介了螺杆挤压机的应用。     

挤压工艺参数对犬粮产品质量影响的研究

以鸡肉、大米为制备犬粮的主要原料,研究机筒温度、物料水分含量、螺杆转速对挤压膨化犬粮品质指标(蛋白消化率、糊化度)的影响本研究首先以挤压参数为双螺杆挤压机的机筒温度、物料水分含量和螺杆转速进行单因素实验进而根据单因素实验结果进行正交实验,并确定出最佳工艺参数研究得出的三个参数的最佳组合为:机筒温度为80-100-130-140℃;物料水分含量为26％;螺杆转速为150r/min 本研究结果对于应用双螺杆技术控制犬粮生产加工的产品质量方面具有一定的理论指导作用.     

同向旋转双螺杆挤压机螺杆的计算机辅助设计

通过ＭＤＴ计算机软件对同向旋转双螺杆挤压机双螺杆进行设计和分析,为探讨不同螺杆结构形式对挤压过程所产生的影响不同螺杆结构形式对挤压过程所产生的影响提供依据。     

客观检验在国产细羊毛毛条加工中的应用

根据对国产原毛客观测试的结果，结合实例对客观检验在毛条加工中的应用进行了讨论。工厂可根据对进厂原毛客观检验的结果，在混毛或配毛时对混合批羊毛的特征和成品毛条的加工性能和质量进行预测和控制。实际生产应用和加工试验表明：运用原毛的特征信息，采用IWTO—31—98标准中的混合批数学公式可对国毛混合批的长度、细度等特征进行较为精确的预测，此外，利用原毛特征和加工性能之间的关系，建立国毛毛条加工预测公式可对成品毛条的纤维豪特长度、长度离散、精梳落毛率和细度等指标进行比较准确的预测。     

Short communication: Feeding method affects the feeding behavior of growing dairy heifers

There is limited information available on what is the most appropriate feeding method for growing dairy heifers. The objective of this study was to determine the effect of feeding method on the feeding behavior and diet selection of growing dairy heifers. Six prepubescent Holstein heifers (158.2 ± 4.0 d old, weighing 168.2 ± 15.7 kg), fed once per day for 1.0 kg/d of growth, were subjected to each of 3 treatments in 3 successive 7-d treatment periods using a replicated 3 × 3 Latin square design. Treatments consisted of feeding 2.02 kg/d dry matter of grain concentrate and ad libitum chopped grass hay as: 1) choice (grain concentrate and hay in separate feed bins), 2) top-dressed ration (grain concentrate placed on top of the hay in one feed bin), and 3) total mixed ration (TMR, grain concentrate mixed with hay in one feed bin). Dry matter intake (DMI) and feeding behavior were monitored for 7 d for each animal on each treatment, and feed sorting was monitored for the last 3 d of each treatment period. The provision of grain concentrate and hay in either a choice or top-dressed situation resulted in young dairy heifers rapidly consuming the grain concentrate portion of their ration in very few, large meals before consuming the hay portion of their ration. The provision of the 2 ration ingredients as a TMR increased the distribution of DMI over the day and reduced the amount of sorting (against long forage particles, and for short grain concentrate particles) by heifers. These results suggest that the provision of a TMR to growing dairy heifers, as opposed to feeding concentrate and hay as either a choice or top-dressed, promotes a more balanced intake of nutrients across the day.     

基于布面毛羽特征变化的织物烧毛效果评价

为探讨织物烧毛效果客观评价的可行性,利用织物单面压缩测试仪测试了织物烧毛前后布面毛羽的特征参数,对烧毛前后各参数的变化情况进行了比较分析,结合烧毛效果的主观评定结果,建立了客观评价织物烧毛效果的指标体系。研究表明:织物烧毛前后布面毛羽的各特征参数均发生了一定变化,且烧毛前后各参数的差异性显著;织物烧毛效果可用烧毛前后布面毛羽各特征参数的变化率进行评价;毛羽长度的变化率在烧毛前后最为显著,在实际应用中可作为织物烧毛效果客观评价的主要依据。     

糖果兼用蔗产量性状对蔗茎产量的效应分析

对12个有望作为糖果兼用蔗品种推广的甘蔗品种的产量性状如株高、茎径、公顷有效茎、蔗茎产量等进行了相关及通径分析。结果表明：株高、公顷有效茎与蔗茎产量之间存在显著、极显著正相关,茎径与蔗茎产量呈不显著负相关。各性状相互之间,株高与公顷有效茎存在不显著正相关,茎径与株高和公顷有效茎存在负相关,其中茎径与株高之间的负相关达显著水平。在对产量的效应中,公顷有效茎对产量的直接效应和总贡献最大,株高次之,茎径最小。由于甘蔗用途的改变(主要用于上市销售),因而在糖果兼用蔗的选育种和生产栽培中把主要目标放在增加公顷有效茎的同时,对植株的茎径也应给予足够的重视。为获得最大经济效益,应注意合理协调好产量三要素之间、特别是株高与茎径之间的关系。     

Short communication: Varying dietary dry matter concentration through water addition: effect on nutrient intake and sorting of dairy cows in late lactation

The objective of this study was to determine if feed sorting can be reduced and if nutrient consumption can be limited in late-lactation cows through water addition to a nutrient-dense total mixed ration (TMR) with a dry matter (DM) content greater than 60%. Twelve lactating Holstein cows (214.8±28.5 d in milk) were exposed to 2 diets in a crossover design with 28-d periods. Diets had the same ingredient composition and differed only in DM percentage, which was reduced by the addition of water. Treatment diets were (1) dry TMR (61.7% DM) and (2) wet TMR (51.9% DM). Dry matter intake and milk production (4% fat-corrected milk; FCM) were recorded for the last 14 d of each treatment period. For the final 4 d of each period, fresh feed and orts were sampled for particle size analysis and subsequent calculation of sorting activity (expressed as a percentage of predicted intake). Adding water to the diet tended to decrease the amount of DM in the fine particle fraction, increase starch concentration in the longer ration particles, and reduce starch concentration in the shortest ration particles. All cows sorted against long ration particles; the extent of this sorting did not differ between the dry and wet treatments (72.9 vs. 77.6%). There tended to be more sorting for fine ration particles on the dry diet compared with the wet (106.3 vs. 104.0%). Water addition had no effect on production, with similar DMI (27.9 vs. 26.5 kg/d), 4% FCM (28.7 vs. 27.6 kg/d), and efficiency of production (0.98 vs. 1.00 kg of 4% FCM/kg of DMI) between the dry and wet treatments. Adding water to a TMR with greater than 60% DM containing primarily haylage and corn silage forage sources may change ration particle DM distribution and particle starch content, possibly contributing to less sorting for the smallest ration particles. This research does not provide evidence that water addition to such a TMR can effectively limit DMI in late-lactation cows and, thus, improve efficiency of milk production.     

Ultrasonographic measurement of the bovine teat: breed differences, and the significance of the measurements for udder health

The objective was to measure teat canal length and diameter, teat diameter and teat wall thickness by ultrasonographic scanning in order to determine the differences in bovine breeds, and to study the influence of teat canal length and diameter on the occurrence of mastitis. A total of 269 lactating dairy cows of four different breeds (Brown Swiss, Simmental, Simmental crossbred with Red Pied, and Holstein-Friesians) from seven Upper Austrian dairy farms were examined. Average teat canal length of Brown Swiss animals was shortest (15.7 mm) followed by Holstein-Friesians (17.2 mm) and Simmental (18.3 mm). These differences in teat canal length were highly significant (P < or = 0.001). There was no significant difference in teat canal length between pure-bred and crossbred Simmentals. Differences of teat canal diameter between breeds were significant (P < or = 0.05). Brown Swiss animals had the largest diameters (2.0 mm) and Holstein-Friesians the smallest (1.7 mm). Differences in teat diameter between Brown Swiss, Holstein-Friesian and Simmental were also significant. No differences were found between the pure-bred and crossbred Simmental cows. The narrowest teats were in Holstein-Friesians and the widest in Simmental. Holstein-Friesians also exhibited the thinnest teat walls while the Simmental had the thickest ones. Teat canal length and diameter were correlated with udder health. Teat canals of healthy udders tended to be longer (17.4 mm) and narrower (1.8 mm) than teat canals of infected udders (15.8 mm, 2.1 mm; P < or = 0.001). A logistic regression model showed significant effects of teat canal length, teat canal diameter and lactation number on udder health.     

等覆盖率变径编织方法

针对鱼雷、炮弹等具有旋转曲面芯轴的编织型保护层覆盖率恒定的问题,提出控制芯轴牵引速度与纱锭转速的比例关系来实现等覆盖率编织的方法。基于对编织物局部结构的分析,建立编织物覆盖率与编织角、芯轴半径和芯轴锥角等编织参数的数学关系模型。首先采用逆解法求解局部编织物编织过程中的牵引速度和纱锭转速;其次应用积分原理将所求速度模型应用到整个编织物,运用MatLab 计算并分析编织点高度、编织角、牵引速度与芯轴半径之间的关系;将所得数据通过Solidworks 软件建立相应的编织物虚拟模型,并对不同部位处织物密度进行对比分析。结果表明,各个部位的织物密度基本一致,证明所建立的数学模型具有可靠性。     

高产梳棉机重定量的思考

针对棉纺工艺重定量、大牵伸的核心是细纱工序提高牵伸倍数、基础是梳棉工序增加生条定量这一前提,通过对大、小直径锡林高产梳棉机重定量工艺的对比分析,指出小直径锡林高产梳棉机的梳理度比大直径锡林梳棉机高得多,但容易伤纤维.国产大直径锡林梳棉机采用重定量,同时降低出条速度在产量不增加的情况下,生条质量可保持原来轻定量时的水平.建议采用重定量时要兼顾出条速度和台时产量.     

The use of mid-infrared spectrometry to estimate the ration composition of lactating dairy cows

The composition of cow milk is strongly affected by the feeding regimen. Because milk components are routinely determined using mid-infrared (MIR) spectrometry, MIR spectra could also be used to estimate an animal's ration composition. The objective of this study was to determine whether and how well amounts of dry matter intake and the proportions of concentrates, hay, grass silage, maize silage, and pasture in the total ration can be estimated using MIR spectra at an individual animal level. A total of 10,200 milk samples and sets of feed intake data were collected from 90 dairy cows at 2 experimental farms of the Agricultural Research and Education Centre in Raumberg-Gumpenstein, Austria. For each run of analysis, the data set was split into a calibration and a validation data set in a 40:60 ratio. Estimated ration compositions were calculated using a partial least squares regression and then compared with the respective observed ration compositions. In separate analyses, the factors milk yield and concentrate intake were included as additional predictors. To evaluate accuracy, the coefficient of determination (R²) and ratio to performance deviation were used. The highest R² values (for kg of dry matter intake/for % of ration) for the individual feedstuffs were as follows: pasture, 0.63/0.66; grass silage, 0.32/0.43; concentrate intake, 0.39/0.34; maize silage, 0.32/0.33; and hay, 0.15/0.16. Estimation of groups of feedstuffs (forages, energy-dense feedstuffs) mostly resulted in R² values >0.50. Including the parameters milk yield or concentrate intake improved R² values by up to 0.21, with an average improvement of 0.04. The results of this study indicate that not all ration components may be estimated equally accurately. Even if some estimates are good on average, there may be strong deviations between estimated and observed values in individual data sets, and therefore individual estimates should not be overemphasized. Further research including pooled samples (e.g., bulk milk, farm samples) or variations in ration composition is called for.