Analysis of land-cover transitions based on 17th and 18th century cadastral maps and aerial photographs

This paper explores the possibility of using non-geometric cadastral maps from the 17th and 18th century together with aerial photographs from 1945 and 1981 to analyse land-cover change in south-east Sweden. Habitats rich in plant species in the European rural landscape seem to be correlated with a long continuity of management. Accurate spatial data from historical data sources are fundamental to understand patterns of vegetation and biodiversity in the present-day landscape. However, traditional methods for rectification of non-geometric maps using corresponding points from orthophotos or modern maps are not satisfying, as internal inaccuracies will remain in the maps. This study presents a method to rectify the maps by local warping, thereby eliminating geometrical irregularities. Further, the land-cover changes were calculated and presented as transition matrices. The extent of arable fields and grasslands were analysed in relation to soil characteristics and continuity of management. The results show a dynamic relation between grassland and arable field, albeit the overall proportions remained almost the same between 17th and 18th centuries: 60% grassland to 32% arable field. The most substantial changes in land-cover were prior to 1945. Today there is 18% grasslands left in the study area, while 56% of the land-cover is arable field. Approximately 8% of present-day land-cover is semi-natural grassland 300 years of age or more. Compared to 300 years ago there is only 1% grassland left on peat and 2% on clay. In contrast, grassland covers associated with bare bedrock have been fairly stable in size. All semi-natural grasslands with a long continuity of management were situated on shallow soils, less than 50 cm depth. The major conclusions from this study are that (i) correctly rectified, old maps are very useful to address questions of land-cover changes in historical time, (ii) general trends in land use over 300 years in this hemi-boreal landscape seem to underestimate the full dynamics of land use change, and (iii) only a small proportion of the semi-natural grassland area had a 300 year continuity of management.     

旋翼/机翼转换式高速直升机RD15方案设计

首先对目前各种类型的高速直升机方案和提高前飞速度的新技术进行了综合比较和分析,在此基础上提出了一种旋翼/机翼转换式高速方案。然后,设计了高速直升机RD15的总体方案和直升机/飞机模式的转换过程。在该方案中,升力系统由盘翼和可收缩的桨叶组成;悬停和低速前飞时的控制采用单片桨叶控制技术;尾部采用矢量推力的涵道螺桨,不仅在悬停时提供方向控制,而且在飞机模式时提供高速前飞的推力和多种控制。最后,对此方案旋翼系统的气动特性和关键技术——直升机/飞机模式转换过程中盘翼的仰角、桨叶的长度、转速以及桨距等参数的变化进行了理论和试验研究,并建立了盘翼/旋翼系统的气动计算模型。计算和试验表明,该方案在直升机/飞机模式相互转化过程中升力、功率和操纵的改变能够实现平滑连续地过渡并保证操稳性。     

The importance of the oxidative status of dairy cattle in the periparturient period: revisiting antioxidant supplementation

Dairy cows are especially vulnerable to health disorders during the transition period, when they shift from late pregnancy to the onset of lactation. Diseases at this stage affect not only the animals' well‐being, but also cause a major economic impact in dairy farms, because apart from treatment costs, affected cows will not reach their peak milk‐producing capacity. The overproduction of reactive oxygen species (ROS) leads to oxidative stress, which has been identified as an underlying factor of dysfunctional inflammatory responses. Supplementation with vitamins and trace elements attempts to minimize the harmful consequences of excessive ROS production, thereby trying to improve animals' health status and to reduce disease incidence. However, results regarding the effects of supplementing antioxidants on dairy cows' health and performance have been inconsistent, because in most cases, the antioxidant potential of the animals was not assessed beforehand and the nutritional strategy planned accordingly. Therefore, reviewing the physiological and harmful effects of ROS production, along with the different options available for assessing the redox balance in dairy cattle and some of the key findings of different supplementation trials, could bring one step forward the on‐farm application of determinations of oxidative status for establishing nutritional strategies early enough in the dry period that could improve transition cow health.     

Continuous measurement of reticuloruminal pH values in dairy cows during the transition period from barn to pasture feeding using an indwelling wireless data transmitting unit

This study was performed to investigate the effect of the transition from barn feeding to pasture on the pattern of reticuloruminal pH values in 8 multiparous dairy cows. A indwelling wireless data transmitting system for pH measurement was given to 8 multiparous cows orally. Reticuloruminal pH values were measured every 600 s over a period of 42 days. After 7 days of barn feeding (period 1), all of the animals were pastured with increasing grazing times from 2 to 7 h/day over 7 days (period 2). From day 15 to day 21 (period 3), the cows spent 7 h/day on pasture. Beginning on day 22, the animals had 20 h/day access to pasture (day and night grazing). To study reticuloruminal adaptation to pasture feeding, the phase of day and night grazing was subdivided into another 3 weekly periods (periods 4–6). Despite a mild transition period from barn feeding to pasture, significant effects on reticuloruminal pH values were observed. During barn feeding, the mean reticuloruminal pH value for all of the cows was 6.44 ± 0.14, and the pH values decreased significantly (p < 0.001) during period 2 and 3 to 6.24 ± 0.17 and 6.21 ± 0.19 respectively. During periods 4, 5 and 6, the reticuloruminal pH values increased again (pH 6.25 ± 0.22; pH 6.31 ± 0.17; pH 6.37 ± 0.16). Our results showed that the animals had significantly lowered reticuloruminal pH during the periods of feed transition from barn to pasture feeding. Despite these significant changes, the decrease was not harmful, as indicated by data of feed intake and milk production.     

基于空间分析的江宁土地利用变化特征的研究

利用多源遥感卫星数据,对江宁3个不同时期的土地利用现状进行解译得到了土地利用类型图,借助地理信息系统空间数据叠置功能以马尔柯夫概率模型的类型转移矩阵对江宁土地利用/覆盖变化进行了分析.结果表明,在近20年的时间里,由于经济的快速发展使城市化水平提高,导致辽宁耕地损失达4214.02hm2这些耕地被转化为城市基础设施建设用地和经济效益较高的养殖业,但人地矛盾日渐突出.     

Synthesis and Rheological Characterization of Water-Soluble Glycidyltrimethylammonium-Chitosan

In this study, chitosan (CS) grafted by glycidyltrimethylammonium chloride (GTMAC) to form GTMAC-CS was synthesized, chemically identified, and rheologically characterized. The Maxwell Model can be applied to closely simulate the dynamic rheological performance of the chitosan and the GTMAC-CS solutions, revealing a single relaxation time pertains to both systems. The crossover point of G′ and Gʺ shifted toward lower frequencies as the CS concentration increased but remained almost constant frequencies as the GTMAC-CS concentration increased, indicating the solubility of GTMAC-CS in water is good enough to diminish influence from the interaction among polymer chains so as to ensure the relaxation time is independent of the concentration. A frequency–concentration superposition master curve of the CS and GTMAC-CS solutions was subsequently proposed and well fitted with the experimental results. Finally, the sol-gel transition of CS is 8.5 weight % (wt %), while that of GTMAC-CS is 20 wt %, reconfirming the excellent water solubility of the latter.     

适宜贮藏温度和添加剂提高苹果粉稳定性

为提高喷雾干燥苹果粉的贮藏稳定性和优化贮藏条件,基于水分活度保藏理论和玻璃化转变理论,探讨了温度及添加剂对苹果粉吸附等温线和玻璃化转变温度的影响。采用静态称量法研究了苹果粉在不同温度(5、25和45℃)下的吸附等温线;采用Lewicki、GAB、Smith、Henderson和Peleg模型拟合试验数据,得到描述苹果粉水分吸附特性的数学模型;采用差示扫描量热法测定了添加β-环糊精、麦芽糊精、可溶性淀粉和玉米淀粉的苹果粉在贮藏温度40℃达到水分平衡时的玻璃化转变温度;采用Khalloufi,El-Maslouhi,Ratti方程拟合数据,探讨添加剂对苹果粉临界水分活度和临界平衡干基含水率的影响。结果表明,GAB模型为描述苹果粉水分吸附特性的适宜模型;苹果粉的平衡干基含水率随着水分活度的增加而增加,水分活度小于0.76时随着温度的升高而降低;苹果粉的玻璃化温度随平衡干基含水率的增加而降低,添加β-环糊精的苹果粉玻璃化温度较高,不易结块,有利于提高苹果粉的贮藏稳定性。研究可为苹果粉适宜干燥技术条件和贮藏条件的确立提供参考。     

近30年阴山南北麓农牧交错带标准耕作制度变化研究

标准耕作制度作为农用地分等定级的基础,是衡量区域农业可持续发展的重要因素。本文基于2012—2013年调研的农户数据、1980—2010年作物播种面积与农业气象数据,从种植结构变化、标准耕作制度类型的空间变化研究了阴山南北麓农牧交错带标准耕作制度的变化规律,并从气候与经济效益两方面进行了变化原因分析。结果表明,1980—2010年,阴山北麓小麦种植面积比例从1980年40.00%下降至2010年的11.48%;莜麦种植面积比例从1980年30%左右下降到2010年的13%左右;马铃薯种植面积逐年增加,种植比重逐渐上升至2010年的47.32%。1980—1990年,阴山南麓小麦种植面积比例逐年增加至1990年21.70%,杂粮种植面积比例稳定在35%左右,同期玉米与马铃薯种植比例较小;1990—2010年,麦类作物种植面积比例逐年下降,2010年小麦种植比例仅为8.55%,杂粮种植面积所剩无几,同期玉米与马铃薯种植面积逐年扩大。标准耕作制度的空间变化特征表现为:阴山南北麓标准耕作制度由小麦、杂粮、小麦与杂粮类型变化为马铃薯、玉米、马铃薯与玉米、小麦与马铃薯类型。气候变化与经济效益共同影响着标准耕作制度的变化,气候暖干化及经济效益低导致麦类作物种植面积大幅度减小,经济效益明显是马铃薯与玉米种植面积迅速增加的主要原因。     

Epoxidized polybutadiene as a thermal stabilizer for poly(3-hydroxybutyrate). I. Effect of epoxidation on the thermal properties of polybutadiene

Polybutadiene (PB) was epoxidized to various extens withm-chloroperbenzoic acid (MCPBA) in homogeneous solution. The thermal properties of the epoxidized PBs were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). As a result of epoxidation the glass transition temperature (T _g) of PB increased by approximately 0.8°C for each 1 mol% of epoxidation. The thermal decomposition of the epoxidised PBs occurred in twostep process, while that of PB exhibited apparent one-step degradation process.