基于图像三维连通性识别方法的长江流域干旱事件特征

全球变化背景下,干旱事件频发给区域水资源管理和社会经济可持续发展带来了巨大挑战,科学合理地辨识干旱发生发展过程一直是干旱研究领域的前沿与难点。该研究将图像三维连通性识别方法应用于气象干旱事件的识别和提取。在长江流域的应用表明此方法识别出的干旱事件与历史记录的吻合度较高,能有效识别气象干旱事件。基于1960—2015年标准化降水蒸散发指数(Standardized Precipitation Evapotranspiration Index, SPEI),长江流域共发生281场气象干旱事件,其中长历时干旱事件(历时大于4个月)64场。长历时干旱事件在流域中部发生次数多于东部和西部,2000年之后的发生频次、干旱面积和干旱强度大于2000年之前,单场事件发展方向以西北和东南为主。整体上,干旱事件发生频次和干旱强度在长江流域中部呈增加趋势,在流域东部和西部呈减小趋势。该研究有助于探索长江流域干旱事件发展演变规律。     

内蒙古大兴安岭森林火险等级评价与区划研究

以内蒙古大兴安岭为研究区,选取树种燃烧类别、人口密度、路网密度、防火期月平均降水量、气温、风速等火险因子数据,运用森林火险等级评价和聚类分析2种方法得出各个林业局及管护局的森林火险等级并完成火险区划。结果表明：伊图里河的森林火险等级为Ⅱ级,为中等火险区（占总面积3.97%）,其他地区为Ⅰ级,为高等火险区（占总面积96.03%）。按照火险程度由高到低分为5类,金河火灾危险性最高为聚类1（占总面积6.04%）;绰源、得尔布尔火灾危险性较高为聚类2（占总面积5.49%）;甘河、阿龙山、克一河、吉文、北大河、图里河、满归、阿尔山、库都尔、绰尔、伊图里河、阿里河火灾危险性高为聚类3（占总面积46.77%）;根河、莫尔道嘎、毕拉河、乌尔旗汉火灾危险性较低为聚类4（占总面积22.97%）;大杨树、管护局火灾危险性低为聚类5（占总面积18.73%）。研究结果可为有关部门制定森林火灾的减灾对策和战略决策提供参考。     

Investigation of the effect of Equivac® HeV Hendra virus vaccination on Thoroughbred racing performance

Objective

To evaluate the effect of Equivac® HeV Hendra virus vaccine on Thoroughbred racing performance.

Design

Retrospective pre‐post intervention study.

Methods

Thoroughbreds with at least one start at one of six major south‐eastern Queensland race tracks between 1 July 2012 and 31 December 2016 and with starts in the 3‐month periods before and after Hendra virus vaccinations were identified. Piecewise linear mixed models compared the trends in ‘Timeform rating’ and ‘margin to winner’ before and after initial Hendra virus vaccination. Generalised linear mixed models similarly compared the odds of ‘winning’, ‘placing’ (1st–3rd) and ‘winning any prize money’. Timeform rating trends were also compared before and after the second and subsequent vaccinations.

Results

Analysis of data from 4208 race starts by 755 horses revealed no significant difference in performance in the 3 months before versus 3 months after initial Hendra vaccination for Timeform rating (P = 0.32), ‘Margin to winner’ (P = 0.45), prize money won (P = 0.25), wins (P = 0.64) or placings (P = 0.77). Further analysis for Timeform rating for 7844 race starts by 928 horses failed to identify any significant change in Timeform rating trends before versus after the second and subsequent vaccinations (P = 0.16) or any evidence of a cumulative effect for the number of vaccines received (P = 0.22).

Conclusion

No evidence of an effect of Hendra virus vaccination on racing performance was found. The findings allow owners, trainers, industry regulators and animal health authorities to make informed decisions about vaccination.     

Ajax在星级评分系统中的应用

在Web应用程序中利用Ajax技术可以实现页面的局部刷新,客户端用户不会感觉到有网页提交或刷新的过程,Web页面也不需要被重新加载,这种方式能使用户得到丰富的应用体验.本文通过网站星级评分系统的实现来学习和和讨论Ajax技术在Web中的应用.     

建筑外墙保温系统防火性能分析与改进方法

本文结合工作实际,综合考虑现有建筑外墙保温系统的保温材料,分析保温系统的火灾风险、防火安全系统影响因素,提出防火隔离带、挡火梁、防火分仓、满粘做法、增加保护层厚度等建筑构造措施,提高保温系统的防火性能,并对其防火分级、发展趋势提出自己的建议。     

中国肉用西门塔尔牛场间遗传联系分析

旨在加快中国肉用西门塔尔牛的遗传进展，实现全国范围内的联合育种。本研究利用全国38家育种场和公牛站在2000—2019年出生的3 991头肉用西门塔尔牛初生重性状，使用DMU软件对场间关联率进行计算。对各场站划分关联组，并比较单场和关联组内的遗传力和估计育种值（estimated breeding value，EBV）的预测准确性。结果表明，中国肉用西门塔尔牛全国平均关联率为1.91%，大部分场间关联率处于较低水平。依据关联率可划分出两个关联组，分别包括6个和8个场，组内平均关联率分别为11.23%和12.54%。对两个关联组分别进行单场和联合估计，单场估计初生重的遗传力范围为0.32~0.44，关联组1的初生重遗传力为0.47，关联组2的初生重遗传力为0.43。两个关联组单场估计EBV的平均准确性分别为0.47和0.45，联合估计EBV的平均准确性分别为0.61和0.56。联合估计较单场估计EBV的准确性有明显提高。依据关联率划分关联组进行联合育种有利于加快中国肉用西门塔尔牛的育种进程。为推进中国肉用西门塔尔牛的育种进程，应先形成区域性联合育种，再逐步加强遗传联系，形成全国范围内的遗传关联体系。     

Some factors effecting the dry matter production of lucerne cultivars

Abstract

Dry matter yields of lucerne cultivars were affected by different factors. A simple equation is given for predicting total dry matter yield of irrigated lucerne based on mean maximum temperatures in January.     

V带传动的计算机辅助设计

运用AutoCAD软件支持的AutoLISP程序设计语言和DCL对话框设计语言,对V带传动的计算机辅助设计系统的开发进行初步探讨。     

天竺葵品种、胡瓜钝绥螨和花粉对西花蓟马为害水平影响

研究了天竺葵品种、释放胡瓜钝绥螨和添加花粉对西花蓟马为害水平的影响。结果表明,是否添加花粉和添加花粉的时间对西花蓟马的为害水平没有影响,而品种对西花蓟马的为害水平有显著影响,并且品种和胡瓜钝绥螨对西花蓟马的为害水平有交互作用,在每一个相同的胡瓜钝绥螨处理下,西花蓟马对品种Sybil Holmes为害水平明显高于Amethyst 96。在不同品种上,胡瓜钝绥螨作用不同,对于品种Sybil Holmes来说,是否释放胡瓜钝绥螨以及不同释放比例对西花蓟马的为害水平没有影响,而对于品种Amethyst 96,在胡瓜钝绥螨与西花蓟马为1∶2高比例释放胡瓜钝绥螨处理下,西花蓟马的为害水平明显低于1∶10低比例释放和没有释放胡瓜钝绥螨的处理。     

A Quantitative Method to Assess Freezing Resistance in Faba Beans

In order to quantify freezing resistance (R₅₀) of winter faba beans from a limited number of plants, leaves were exposed to artificial freezing stresses with different test temperatures (TT_i). Injury (I_i) was assessed by rating (score: 0—8) and by conductivity measurements. The basic assumption that I_i depends almost linearly on TT_i over a sufficiently broad range with a constant ΔI/ΔTT could be verified and hence a formula is presented to compute freezing resistance R₅₀= (I_i—I₅₀) ×ΔTT/ΔI + TT_i with I₅₀ being a medium injury. This formula allows to quantify resistance by assessing I_i after freezing test(s) with definite TT_i. About 25 leaves are required. Rating appeared preferable to conductivity measurements because of easier and quicker performance and a slightly better discrimination between samples of different resistance. Based on a standardized freezing test, ΔI/ΔTT was determined. Application of the formula with ΔI/ΔTT = 2.5 units/°C for unhardened and hardened leaves, restrictions and experiences are discussed.