U形渠道圆头量水柱测流影响因素试验及模拟

为研究U形渠道圆头量水柱的测流规律及影响因素,基于绕流理论和RNG k-?湍流模型,对18种体型圆头量水柱5种工况下的水力性能进行全流场数值计算,获得了时均流场、断面流速分布及柱后水流流态,并与实测值进行对比。同时,通过模型试验与数值仿真研究了V形尾翼对测流的影响。结果表明：水力参数的实测值与模拟值具有较好的一致性,渠道底坡为1/1 000,流量为45.01 L/s,收缩比及长宽比分别为0.50和2时,驻点处横断面最大流速模拟值与实测值相对误差为1.51%,水深15 cm位置剖面最大流速模拟值与实测值相对误差为0.45%。适宜长宽比的V形尾翼可以有效改善过槽水流：当收缩比为0.50～0.75时,建议长宽比为3/2～2;当收缩比＜0.50时,长宽比应相应增大,但不宜＞5/2。通过回归分析得到的圆头量水柱流量计算公式,在收缩比为0.63时最大测流误差为4.95%,平均误差仅为0.10%,该研究为圆头量水柱在中国北方灌区末级渠系的进一步应用提供参考。     

Challenges in developing and implementing a decision support systems (ETÇAP) in forest management planning: a case study in Honaz and Ibradı, Turkey

Decision support systems (DSSs) are indispensable tools in preparing a forest management plan for a better combination of multiple forest values. This study attempted to develop and explain a stand-based forest management DSS (Ecosystem-based multiple-use forest planning [ETÇAP]) comprising a traditional simulation, linear programming (LP), metaheuristics and geographic information system. The model consists of five submodels; traditional management approach to handle inventory data, an empirical growth and yield model, a simulation to conceptualize management actions, a LP technique to optimize resource allocation and a simulated annealing approach to directly create a spatially feasible harvest schedule. The ETÇAP model has been implemented in a comparative two case study areas; Denizli–Honaz and Akseki–Ibrad?. Both simulation and optimization models outperformed to the traditional management plan. The periodical change of growing stock, allowable cuts, carbon sequestration and water production are used as performance indicators. The results showed that more amount of wood could be harvested over time compared to traditional level of harvesting. It could be concluded that various management strategies allowed managers to stimulate more decision options for better outputs through intertemporal trade-offs of management interventions as the model provided tools to quantify forest dynamics over time and space. Challenges exist to establish the functional relationships between forest structure and values for better quantification and integration into the management plans.     

棉花SSR-PCR过程中聚丙烯酰胺凝胶电泳操作常见问题的解决与优化

在大批量聚丙烯酰胺凝胶电泳过程中,难免会出现条带空白、弯曲或者拖尾等各种异常现象。本文以棉花DNA为例,综述了多年实验操作中遇到的突发情况及解决方法,为广大科研工作者提供参考。     

Production,chemical composition,and fatty acid profile of milk from buffaloes fed with cupuaçu (Theobroma grandiflorum) cake and murumuru (Astrocaryum murumuru) cake in the Eastern Amazon

The objective was to evaluate the effect of concentrate supplementation using by-products of the Amazonian industry on milk production, milk composition, and milk fatty acid profile of dairy buffaloes. Twelve lactating buffaloes (544.5 ± 35.6 kg, 6.4 ± 2.2 years old, 59 ± 6 days in milk) were allotted in a pasture of Mombaça grass and managed under rotational grazing (4 days occupancy/28 days rest). A 3 × 3 Latin square was adopted, and each animal alternately received three supplementary treatments based on corn bran + soybean meal or cupuaçu cake or murumuru cake for 21 days per treatment. Murumuru cake increased the levels of lauric acid and myristic acid in the milk (p < 0.05). Murumuru cake reduced the unsaturated fatty acid contents in the milk compared with animals fed control diet or cupuaçu cake (24.27% vs. 25.24% vs. 25.08%). The n-6/n-3 ratio was 2.6, 1.97, and 2.0 in the control, cupuaçu, and murumuru groups, respectively. Based on this parameter, cakes made from cupuaçu as well as murumuru could be considered to be adequate for inclusion in dairy water buffalo feed. However, the murumuru cake addition requires some caution because its use induces the secretion of higher levels of lauric and myristic fatty acids that are related to human cardiovascular disease.     

Effects of cerium oxide supplementation to laying hen diets on performance,egg quality,some antioxidant enzymes in serum and lipid oxidation in egg yolk

This study was conducted to determine the effects of dietary cerium oxide levels (0, 100, 200, 300 or 400 mg/kg) on the laying performance, egg quality, some blood serum parameters and egg lipid peroxidation of laying hen. In total, one hundred and twenty 22‐week‐old brown Lohman LSL laying hens were randomly assigned to five groups equally (n = 24). Each treatment was replicated six times. Dietary supplementation of cerium oxide had no significant effect on feed intake and egg weight. The addition of cerium oxide to the laying hens' feed improved feed conversion ratio and increased (p < 0.05) egg production. Quality criteria of egg for except shell breaking strength were not affected by supplementing cerium oxide. In particular, supplementation of 200 and 300 mg/kg cerium oxide to the laying hens feed led to a significant (p < 0. 01) increase in egg shell breaking strength. Calcium and phosphorus concentration of serum increased significantly (p < 0.05) with supplementation of 100 mg/kg cerium oxide to laying hen diets. It was also observed that serum superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration decreased significantly with supplementation of cerium oxide in diets. Inclusion of cerium oxide resulted in a significant reduction in thiobarbituric acid reactive substance (TBARS) values in egg yolk in this study. It can be concluded that the addition of cerium oxide had positive effects on egg production, feed conversion ratio and egg shelf life. Based on the results of this study, it could be advised to supplement laying hens feed with cerium oxide as feed additives.