干热河谷区土地利用与生态系统服务价值——以云南省元谋县为例

基于RS和GIS理论和方法,以干热河谷区云南省元谋县为例,对2008年和2016的Landsat遥感影像进行解译,分析土地利用格局演变特征,评估区域生态系统服务静态价值和动态价值,探讨生态系统服务价值变化原因。结果表明:耕地、林地和建设用地面积增长,草地、未利用地和水域面积下降。建设用地转入特征和未利用地转出特征较为明显。2008年和2016年区域生态系统服务总静态价值分别为25.98亿元和26.54亿元,总动态价值分别为9.179亿元和16.004亿元。虽然生态系统服务总动态价值仅为同期总静态价值的35.40%和60.30%,但其增长率为74.01%,明显高于总静态价值变化率(2.27%)。土壤形成与保护的单项生态系统服务静态价值最高,2008年和2016年其值分别为4.91亿元和5.03亿元。农业经济发展、城市扩张和人口增长导致耕地、建设用地的扩张和未利用地的减少,水土保持和生态综合治理促进了林地面积的恢复。支付能力和支付意愿的显著提升极大地促进了生态系统服务总动态价值的增长。因此,应强化区域土地利用的空间调控,继续实施水土保持和退耕还林还草等生态治理工作,以维护干热河谷区生态系统功能,实现区域可持续发展。     

Compatibility of root growth and tuber production of potato cultivars with dynamic and static water‐saving irrigation managements

The important root characteristics of root length density (RLD) and root mass density (RMD) generally differ among irrigation managements and potato cultivars. The objective of this study was to investigate the RLD and RMD variations and their functional relationships with gross potato tuber yield for two commercial potato cultivars, Agria and Sante, under different irrigation strategies. Full irrigation and water‐saving irrigation strategies, deficit and partial root drying irrigations, were applied statically (S) and dynamically (D) based on daily crop evapotranspiration. Results showed that SPRD had significantly greater RLD (3.64 cm/cm³) and RMD (132.7 μg/cm³) than other irrigation treatments. Between the potato cultivars, Agria had significantly larger values of RLD (3.50 cm/cm³) and RMD (138.7 μg/cm³) than Sante. The functional relationship between the root growth characteristics and tuber yield showed that under water‐saving irrigations, Agria increased root mass at the expense of gross tuber yield but Sante increased root mass to maintain larger gross tuber yields. However, Agria produced more roots and gross tuber yield than Sante, and it is concluded that Agria is a more drought‐tolerant potato cultivar, which is recommended for tuber production in regions where water might be scarce. It was shown that larger root production in potatoes was associated with improved tolerance to water stress.     

Whole body vibration affects the cross‐sectional area and symmetry of the m. multifidus of the thoracolumbar spine in the horse

Whole body vibration (WBV) has been used as an adjunctive therapy to improve the strength and size of paraspinal muscles as well as postural control in people with lower back pain. It has been proposed that activation of the m. multifidus plays a key role. As the function and anatomy of the m. multifidus in the horse is comparable to that in man, the authors investigated whether WBV might also be a valuable physiotherapeutic modality in horses. The effects of WBV on the cross‐sectional area (CSA) and left to right symmetry of the m. multifidus at various locations of the thoracolumbar spine of the horse was evaluated in a single‐subject quasi‐experimental time‐series design with repeated measure. Nine horses were subject to WBV, 30 min, twice daily, 5 days a week, for 60 days in addition to their regular exercise routine. The CSA of the left and right m. multifidus was measured ultrasonographically at four levels (T15–T16, T16–T17, T18–L1 and L1–L2) along the thoracolumbar spine at Days ?30, 0, 30 and 60 of the study. Changes in the CSA and CSA symmetry (left to right) of the m. multifidus were analysed using nonparametric, repeated measures, comparison of mean ranks with post‐hoc analysis as necessary. A significant increase (P<0.05) in m. multifidus CSA was found at all spinal levels after 30 and 60 days of WBV and a statistically significant improvement in m. multifidus symmetry (becoming more symmetrical) was found after 60 days of WBV, indicating that WBV may be a valuable alternative to dynamic mobilisation exercises when an increase in size and improvement in left to right symmetry of the m. multifidus is sought.     

光滑双向渐进结构优化法拓扑优化连续体结构频率和动刚度

针对双向渐进结构优化(bi-directional evolutionary structural optimization, BESO)方法的单元过删除问题,提出了光滑双向渐进结构优化(smooth bi-directional evolutionary structural optimization, SBESO)方法,通过引入权重函数更新单元的质量与刚度矩阵,控制单元删除率以使低效单元逐渐从设计域中删除。以连续体结构固有频率最大化为目标,提出了一种基于SBESO的频率优化方法,对比分析了常函数、线性函数和正弦函数等不同权重函数对连续体结构优化的影响。将等效静载荷(equivalentstatic loads,ESL)方法与SBESO方法相融合,提出了动载荷作用下连续体结构的动刚度优化方法。数值算例表明,SBESO方法通过调节单元删除率和权重函数,控制低效单元在结构设计域中逐渐被删除,有效抑制了单元的过删除问题。采用线性和正弦权重函数,更有利于获得连续体结构的频率最优拓扑解。随单元删除率的减少,动刚度最优拓扑解的结构边界逐渐光滑,而且逼近于同一构形。由此,所提出的SBESO方法完善了BESO方法的优化准则,对于解决连续体结构动力学优化设计问题具有较为重要的理论意义。     

甘南臧区太阳能主被动联合采暖系统性能

中国藏区冬季太阳能仍然十分丰富，太阳能采暖潜力巨大。为了利用太阳能实现清洁供暖，以甘肃省合作市上浪坎木村2座含被动式阳光间建筑面积为170 m2的单体建筑为研究对象，其中一座使用被动式阳光间和太阳能集热器循环加热采暖，另一座使用被动式阳光间和牛粪直燃炉采暖，在相同的环境条件下对比研究了室内热环境、系统经济性和环境效益，研究结果表明：在48 d的测试期内，太阳能主被动联合采暖系统中客厅温度47 d高于14 ℃，只有1 d室内最低温度为13.3 ℃，太阳能主被动联合采暖系统很好地满足了建筑采暖需求，被动式阳光间和牛粪直燃炉联合采暖室内温度不均匀，温差大，客厅温度普遍低于12 ℃；太阳能主被动联合采暖系统比被动式阳光间和牛粪直燃炉联合采暖每个采暖季节省标煤4.3 t，可减少CO2、粉尘、SO2、NOx排放量依次为10.7，2.92，0.322和0.161 t，动态投资回收期4.9 a，证实了系统的可行性、节能性和经济性，可用于指导不同地区太阳能主被动结合供暖系统的优化设计和推广应用。     

青海省旅游气候舒适性评价及不利因素分析

利用1971-2000年的气候数据,对青海省气候舒适性进行了评价,得出如下结论：河、湟谷地气候条件最优,旅游适宜期为5～8月,3月和10月舒适度稍差,11月～次年2月为旅游不舒适期;柴达木地区旅游最适宜期为6～8月,4月、10月、11月～次年3月气温降低,进入旅游不舒适期;祁连山、青海湖地区适宜期只有7、8月,三江源最...     

深圳市生态风景林的人体舒适效应

文章通过同步观测深圳市生态风景林的几种绿地类型地区的温湿度、风速、空气正负离子浓度、可吸入颗粒物含量,对比研究几种绿地类型地区的人体舒适效应,结果表明:几种绿地类型的人体舒适效应顺序为:森林公园>风景林地>居民区绿地>街头绿地。     

松原龙华松花江特大桥悬浇施工风载分析

采用Ansys程序对龙华松花江特大桥施工悬浇阶段刚构桥墩进行风荷载内力分析,保证其结构在自重和静阵风荷载下可以安全施工.     

基于体压分布的床垫硬度对人体舒适性的影响

床垫作为睡眠的平台，其支撑性能对人体健康和睡眠舒适性有着重要的影响。在定量化研究床垫软硬度的基础上，利用体压分布测试，通过软硬度适宜的床垫与硬度较大的床垫进行对比分析，研究床垫软硬度对人体舒适性的影响。结果表明：(1)软硬度适宜的床垫有利于人-床界面压力的分散性，有利于人体腰部支撑；(2)适宜于男性受试者的床垫的软硬度小于适宜于女性受试者的床垫软硬度。