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1.
In an effort to extract additional data from farinograph experiments a model was developed to simulate the measurements and correlate the parameters of the model with results from baking tests. This additional information can be used in bakeries to predict the baking properties of the flours and adjust the recipes to maintain a constant product quality. For this eight different flours were characterized with a farinograph and 13 different results from baking experiments. An approach with five nonlinear differential equations was able to model the farinograph measurements very well (average R2 = 0.995 ± 0.005). While a stepwise multilinear regression only showed weak correlations in cross validation between a single parameter of the model and the baking volume (R2 = 0.745) and the volume yield (R2 = 0.796) respectively, the artificial neuronal network was more successful. For the baking weight (R2 = 0.926), the dough yield gross (R2 = 0.909) and net (R2 = 0.913) strong correlations were found. A good correlation for the baking volume (R2 = 0.853) was also determined, while the volume yield showed comparable results to the linear regression (R2 = 0.792). 相似文献
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Recirculating aquaculture systems (RAS) can be installed indoors, allowing year-round production of tropical animals in nearly any climate. A nursery phase is commonly used in Litopenaeus vannamei production since it allows for enhanced biosecurity and better quantification of animals while reducing space requirements. However, it is unclear whether animal density and inclusion of artificial substrate may improve shrimp performance during the nursery phase. In this experiment, we compared shrimp production parameters in two stocking densities with or without the use of an artificial substrate by creating four treatments: low-density LD; 1500 PL/m−3, low-density with substrate LDS, high-density HD; 3000 PL/m−3), and high-density with substrate (HDS). The LDS and HDS treatments included 0.46-m2 of high-density polyethylene 2.5-cm mesh as a substrate, which increased the tank surface area by 21 %. Each treatment was randomly assigned to four 160-l culture tanks, each with a biofilter. The shrimp had an initial weight of 4 mg and were grown for 50 days. The low-density treatments had significantly higher dissolved oxygen (DO) and pH than the high-density treatments (P ≤ 0.001). Specifically, LDS had the highest DO and pH followed by the LD, HD, and HDS treatments, respectively. High-density treatments had significantly higher NO2-N levels than low-density treatments during week 2 of the experiment when an unusually high concentration of nitrite was observed. FCR was significantly lower in both low-density treatments than in high-density treatments. At harvest, the total biomass (kg m−3) was significantly higher in high-density treatments than in low-density treatments (P ≤ 0.001), and the HDS treatment had a significantly greater biomass output than HD. Producers should consider artificial substrate and higher densities during nursery production to maximize shrimp production; however, the effects on water quality should also be taken into account. 相似文献
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本文描述了落叶松人工林抚育后径级结构特征。试验表明,抚育后的林分在一定密度条件下,其密度遵从Weibull分布,并能保持相当长的时间不变;其密度较大,Weibull参数值在2~3间变动,b值在6~8间变动;稀疏时不能用Weibull分布模拟。 相似文献
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Abstract – Foraging juvenile fish with relatively high food demands are usually vulnerable to various aquatic and avian predators. To compromise between foraging and antipredator activity, they need exact and reliable information about current predation risk. Among direct predator-induced cues, visual and olfactory signals are considered to be most important. Food intake rates and prey-size selectivity of laboratory-reared, naive young-of-the-year (YOY) perch, Perca fluviatilis , were studied in experiments with Daphnia magna of two size classes: 2.8 and 1.3 mm as prey and northern pike, Esox lucius , as predator. Neither total intake rate nor prey-size selectivity was modified by predator kairomones alone (water from an aquarium with a pike was pumped into the test aquaria) under daylight conditions. Visual presentation of pike reduced total food intake by perch. This effect was significantly more pronounced (synergistic) when visual and olfactory cues were presented simultaneously to foraging perch. Moreover, the combination of cues caused a significant shift in prey-size selection, expressed as a reduced proportion of large prey in the diet. Our observations demonstrate that predator-induced olfactory cues alone are less important modifiers of the feeding behaviour of naive YOY perch than visual cues under daylight conditions. However, pike odour acts as a modulatory stimulus enhancing the effects of visual cues, which trigger an innate response in perch. 相似文献
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评价适合选育加工型马铃薯品种的杂交组合 总被引:1,自引:0,他引:1
中国马铃薯的种植面积和产量均占世界首位,随着人们生活水平的提高和饮食结构的改善,以及外资企业在中国的纷纷建厂,对食品加工型马铃薯品种的市场需求日益增加,食品加工型马铃薯品种的培育已成为当务之急。本文根据食品加工型马铃薯品种的6项选育指标(炸制品质、薯形、产量、大中薯率、抗病性、熟期),对14个马铃薯杂交组合进行单个指标的评价和组合的级别评价,最终确定组合F81109×B5141-6、B5141-6×F58050、F67128×F61101、F49013×F61101、F71002×F59103可作为选育食品加工型马铃薯品种比较有前景的杂交组合。 相似文献
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