基于辐射和温度的ET0模型在吐鲁番地区的比较与修正

利用吐鲁番地区3个气象站2000—2015年逐日气象资料,以FAO-56 Penman-Monteith(FAO-56 PM)模型为标准,对6种ET_0模型(M-A模型、P-T模型、M-H模型、H-S模型、Traj模型和B-H模型)进行评价并修正,采用均方根误差(RMSE)、绝对平均误差(MAE)、平均相对误差(MRE)评价指标和Wilcoxon非参数检验法比较年、月尺度上各模型修正前后的估算精度,以筛选适用吐鲁番地区ET_0简化估算模型。结果表明:吐鲁番地区ET_0的主要影响因子是R_s(太阳辐射),其次是e_s(饱和水汽压)和R_n(作物表面净辐射);修正前,年尺度上,M-H模型的估算精度最高;月尺度上,各模型误差较大且与FAO-56 PM模型存在显著差异,适用性较差;修正后,各模型在年、月尺度上的精度均有明显提高,无显著差异,其中修正后的P-T、M-H和B-H模型估算精度最高,可作为吐鲁番地区ET_0简化估算模型。     

浑善达克沙地杨树水分利用特征

为探究浑善达克沙地杨树的水分利用特征。本文利用氢和氧同位素示踪技术,测定了降雨、土壤水与地下水的δ18O值,利用多元线性混合模型定量计算了杨树对不同土层土壤水分的利用比例。结果表明:①浑善达克沙地大气降雨方程线为:δDLWML=7.84δ^18OLWML+9.12,斜率比全国降雨方程偏小,体现了研究区降雨少,蒸发大的气候特征;②土壤含水量与地下水位埋深、降雨量、植物生长期的变化有着显著的相关关系。降雨量较大与地下水位埋深较浅的时期,土壤含水量明显增大,在植物生长前期和中期,土壤含水量明显较低;③杨树在雨季,利用了大量的浅层土壤水(0~40 cm),在较为干旱的旱季,利用了大量的深层土壤(160~200 cm)水与少量的地下水。     

Improving wood volume predictions in dry tropical forest in the semi-arid Brazil

The volumetric variability of dry tropical forests in Brazil and the scarcity of studies on the subject show the need for the development of techniques that make it possible to obtain adequate and accurate wood volume estimates. In this study, we analyzed a database of thinning trees from a forest management plan in the Contendas de Sincorá National Forest, southwestern Bahia State, Brazil. The data set included a total of 300 trees with a trunk diameter ranging from 5 to 52 cm. Adjustments, validation and statistical selection of four volumetric models were performed. Due to the difference in height values for the same diameter and the low correlation between both variables, we do not suggest models which only use the diameter at breast height (DBH) variable as a predictor because they accommodate the largest estimation errors. In comparing the best single entry model (Hohenald-Krenn) with the Spurr model (best fit model), it is noted that the exclusion of height as a predictor causes the values of 136.44 and 0.93 for Akaike information criterion (AIC) and adjusted determination coefficient (R2 adj), which are poorer than the second best model (Schumacher-Hall). Regarding the minimum sample size, errors in estimation (root mean square error (RMSE) and bias) of the best model decrease as the sample size increases, especially when a larger number of trees with DBH≥15.0 cm are randomly sampled. Stratified sampling by diameter class produces smaller volume prediction errors than random sampling, especially when considering all trees. In summary, the Spurr and Schumacher-Hall models perform better. These models suggest that the total variance explained in the estimates is not less than 95%, producing reliable forecasts of the total volume with shell. Our estimates indicate that the bias around the average is not greater than 7%. Our results support the decision to use regression methods to build models and estimate their parameters, seeking stratification strategies in diameter classes for the sample trees. Volume estimates with valid confidence intervals can be obtained using the Spurr model for the studied dry forest. Stratified sampling of the data set for model adjustment and selection is necessary, since we find significant results with mean error square root values and bias of up to 70% of the total database.     

基于MOOC的阿坝州藏汉双语"一类模式"地理教师继续教育研究

藏汉双语“一类模式”已经成为阿坝州最具地方特点和民族特色的教育模式,但藏汉双语地理老师极度缺乏,传统的培训模式存在诸多不足。MOOC的出现正好弥补了这些不足,在阿坝州藏汉双语“一类模式”地理教师继续教育中具有明显优越性。结合阿坝师范学院对汶川县水磨中学地理教师培训的经验,梳理了现有的MOOC地理资源,最终构建了“学用结合,以用促学”的新型继续教育模式。     

软基水闸底板脱空动力学反演模型构建与试验验证

软基水闸极易因地基不均匀沉降、渗透变形等发生底板脱空现象，传统的无损检测方法难以在水下探测底板脱空，且不具实时性，其应用还存在一定局限性。该研究基于软基水闸室内物理模型，提出了一种软基水闸底板脱空动力学反演方法。首先，基于多参数变量的底板脱空范围数学模型，改进了反映软基水闸底板脱空参数与水闸动力学参数（模态参数）之间非线性映射关系的数学代理模型；其次，以水闸多测点多阶频率和振型变化率组合作为动力学敏感特征量，建立了软基水闸底板脱空参数反演的目标函数，并基于遗传算法对目标函数进行求解。最后，建立了软基水闸室内物理模型，并在模型中设置3种不同的底板脱空工况，采用软基水闸底板脱空动力学反演方法对软基水闸底板的脱空进行反演识别与模型验证。结果表明：基于动力学参数反演识别的水闸底板脱空区域趋势和脱空面积与模型实际脱空情况吻合较好，3种工况下水闸底板脱空面积反演结果与模型实际脱空面积的相对误差分别为7.47%、6.78%、6.90%，验证了该方法的可靠性，可望为软基水闸实际工程底板脱空隐患检测提供一种新的思路。     

绿色经济体系下饲料企业经济模式转变研究

近年来,绿色经济成为席卷全球的潮流。绿色经济带给经济社会的改变将是全面而深刻的,饲料行业也不会例外。绿色经济既会给饲料行业带来落后产能淘汰、产业结构升级的机遇,也会带来利润下降、承包上升的短期阵痛。饲料企业想要抓住机遇、迎接挑战,就必须尽快转变当前的经济模式,建立绿色企业文化,加大研发投入,调整生产模式,加强上下游产业链的选择和配合,如果遇到资金困难,可以利用绿色金融进行融资。     

饲粮精料水平和蛋氨酸铬添加剂量对舍饲滩羊生长性能、屠宰性能、肉品质和脂肪沉积的影响

本试验旨在探究饲粮精料水平和蛋氨酸铬(Cr-Met)添加剂量对舍饲滩羊生长性能、屠宰性能、肉品质和脂肪沉积的影响。采用2×3双因素试验设计,2个因素分别为饲粮精料水平和Cr-Met添加剂量,其中饲粮精料水平分别设为35%(低精料饲粮,饲粮精粗比为35∶65)和55%(高精料饲粮,饲粮精粗比为55∶45),Cr-Met添加剂量分别设为0、0.75和1.50 g/(d·只)。将60只雄性滩羊羔羊[平均体重为(21±1)kg]随机分配到6个试验组,每组10只。试验期为80 d,其中预试期15 d,正试期65 d。结果显示:1)与低精料饲粮组相比,高精料饲粮组滩羊的平均日增重、屠宰率、背膘厚度、肌内脂肪含量和后腿肉比重显著增加(P<0.05),但料重比与肌肉蒸煮损失、剪切力、pH、亮度(L*)值、红度(a*)值和黄度(b*)值则显著降低(P<0.05)。2)低精料饲粮组滩羊背膘厚度、皮下脂肪厚度、肌内脂肪含量和后腿肉比重随Cr-Met添加剂量的增加而线性降低(P<0.05),但肌肉pH则线性升高(P<0.05)。3)高精料饲粮组滩羊肋肉比重、腰肉比重以及肌肉剪切力和pH随Cr-Met添加剂量的增加而线性升高(P<0.05),而肌内脂肪含量和肌肉a*值则线性降低(P<0.05)。综合本试验测定指标,建议在滩羊养殖中选择精粗比为55∶45的高精料饲粮,Cr-Met的适宜添加剂量为1.50 g/(d·只),且不建议在精粗比为35∶65的低精料饲粮中添加Cr-Met。     

Monitoring shrimp growth with control charts in aquaculture

This work proposes a method for the statistical monitoring of the weekly weight of shrimp in a fish farm. The design of control charts for shrimp growth presents several challenges, the main ones being the presence of trend and autocorrelation. Several control charts are proposed, the most efficient being a chart based on the residuals of a second order autoregression whose parameters vary with the week. A control chart with less computational complexity is also provided. It is simply based on growth rates and works well at detecting negative weight changes. Real data from a large shrimp farm has been used for both the design and the evaluation.     

Effects of three methionine sources in diets on temporal B0AT1 and ASCT2 mRNA expression in different intestinal segments of cobia,Rachycentron canadum

A 4‐week feeding trial was conducted using five groups of hybrid grouper (61.15 ± 0.15 g) to explore the potential effects of three methionine (Met) sources. Five isonitrogenous and isolipidic diets were formulated that included a fishmeal (FM) diet; nonsupplemented (NS) diet; or NS diets with the addition of the L‐methionine (L‐Met), DL‐methionine (DL‐Met), or coated Met (Co‐Met) to obtain the same Met level as the FM diet. Fish were randomly distributed into sea cages (30 fish per cage). Weight gain and specific growth rate in the DL‐Met group and FM group were significantly higher than those in all other groups (p < .05). In the proximal and distal intestines, of the 20 gene and time combinations (10 per gene), there were 14 combinations (70%) in which there were no significant differences in gene expression levels between the FM and DL‐Met groups (p > .05). The main reason for the same growth effect between the DL‐Met and FM groups may be attributed to the synchronized absorption at most time points after feeding, which had similar expression patterns of B⁰AT1 and ASCT2 of the proximal and distal intestines between two groups.     

多营养层次生态养殖模式简析

系统介绍了多营养层次生态养殖模式在淡水养殖及海水养殖中的应用与发展,对比了国内外有关该养殖模式发展方向的异同,简述了该养殖模式通过提高物质和空间利用率、改善养殖环境的原理以及在我国推广应用情况,并汇总了我国沿海省份近年来开展该养殖模式选用的品种搭配及产量产值。指出了多营养层次生态养殖模式还存在的问题,对今后发展提出了建议。