"机械制图与计算机绘图"精品课程的建设

论文从教师队伍建设、教材编写和课程体系改革、教学内容与教学方法创新、考核评价体系构建等方面介绍机械制图与计算机绘图精品课程建设实践。     

REINTEGRATION OF CROP-LIVESTOCK SYSTEMS IN EUROPE: AN OVERVIEW

• ICLS combines the benefits of specialization with increased resilience of the system.• Clear opportunities but also barriers for ICLS were observed.• ICLS need to be embedded within future environmental legislation.• ICLS systems with a range of intensities are needed to support a biodiverse landscape.Ongoing specialization of crop and livestock systems provides socioeconomic benefits to the farmer but has led to greater externalization of environmental costs when compared to mixed farming systems. Better integration of crop and livestock systems offers great potential to rebalance the economic and environmental trade-offs in both systems. The aims of this study were to analyze changes in farm structure and review and evaluate the potential for reintegrating specialized intensive crop and livestock systems, with specific emphasis on identifying the co-benefits and barriers to reintegration. Historically, animals were essential to recycle nutrients in the farming system but this became less important with the availability of synthetic fertilisers. Although mixed farm systems can be economically attractive, benefits of scale combined with socio-economic factors have resulted in on-farm and regional specialization with negative environmental impacts. Reintegration is therefore needed to reduce nutrient surpluses at farm, regional and national levels, and to improve soil quality in intensive cropping systems. Reintegration offers practical and cost-effective options to widen crop rotations and promotes the use of organic inputs and associated benefits, reducing dependency on synthetic fertilisers, biocides and manure processing costs. Circular agriculture goes beyond manure management and requires adaptation of both food production and consumption patterns, matching local capacity to produce with food demand. Consequently, feed transport, greenhouse gas emissions, nutrient surpluses and nutrient losses to the environment can be reduced. It is concluded that reintegration of specialized farms within a region can provide benefits to farmers but may also lead to further intensification of land use. New approaches within a food system context offer alternatives for reintegration, but require strong policy incentives which show clear, tangible and lasting benefits for farmers, the environment and the wider community.     

Ecological traits of fish assemblages from Mediterranean Europe and their responses to human disturbance

Abstract  Mediterranean river systems are characterised by more diverse fish assemblages and regional ecological processes compared with the rest of Europe. A data set from Mediterranean France, Iberia and Greece (∼2000 sites) was used to describe the characteristics of fish assemblages, explore their responses to anthropogenic disturbance and analyse the implications for river quality assessment. There was a southwards decline in species richness per site, but endemicity and proportion of alien species increased. Sites in the eastern Mediterranean had higher endemicity, lower site richness and lower number of alien species than sites in western Mediterranean Europe. Assemblage composition differed between Mediterranean sub-regions, but was dominated by three major fish types: a salmonid fish type common throughout the study area and two cyprinid-dominated fish types (in some sub-regions, Salmo trutta L. is present but not numerically dominant), corresponding to a gradient in hydrological and temperature regimes. Metric responses to perturbation were compared with those found at the European (larger scale) and basin (smaller scale) levels. Overall metric response was weaker in this Mediterranean application. The best responses to human pressure were usually obtained with abundance-based metrics and included the contribution of naturalised alien species. Some widespread alien species contributed to the response to anthropogenic alteration (notably Cyprinus carpio L. and Lepomis gibbosus (L.)).     

Environmental control of Northeast Atlantic mackerel (Scomber scombrus) recruitment in the southern Bay of Biscay: case study of failure in the year 2000

We investigate the effect of strong meteorological perturbations in early spring on the success of mackerel (Scomber scombrus) recruitment in the N/NW Iberian area (southern Bay of Biscay) for the period 1999–2008. In 2000, the year of the most pronounced recruitment failure on record, two consecutive multidisciplinary surveys sampled hydrographic conditions and mackerel eggs, larvae and post‐larvae over the main mackerel spawning grounds of the north and northwest coast of the Iberian Peninsula. Analysis of egg and larval abundance and birthdates based on the otoliths of mackerel juveniles caught between July and October 2000 showed that there were no survivors from the early spring spawns, indicating a massive loss of early spawning effort. Moreover, the abundance of 1‐year‐old mackerel estimated from an acoustic survey carried out in 2001 was the lowest observed within the 1999–2008 time series. This low or null survival from the early spawns in 2000 could be due to the meteorological and oceanographic conditions of that spring, in particular two storm events in April after a relatively calm March. The first storm event from the north caused strong local wind in the southern Bay of Biscay but a weak oceanographic response. The second storm event from the southwest was mainly felt west of Galicia and caused a notable increase in shelf currents and a shift of the hydrographical structure along the shelf. Detailed analysis of strong wind pulses in early spring within the historical recruitment record suggests that strong local turbulence generated by high wind speeds and advection of larvae caused by the enhancement of shelf currents can contribute to reduced recruitment. Our observations indicate that, in 2000, both mechanisms were present.     

Neoglyphea inopinata: A Crustacean "Living Fossil" from the Philippines

The discovery of an existing member of the Glypheidae, a family believed to have been extinct since the Eocene, may yield significant information on the evolution and classification of the decapod Crustacea. The single known specimen displays characters not apparent in fossil material, some of them perhaps representative of an ancestral decapod lineage, others reminiscent of the Astacidea and Thalassinidea.     

Distribution and abundance of two species of codlet (Teleostei, Bregmacerotidae) larvae from the south-eastern Brazilian Bight

Two species of codlet (Bregmacerotidae) larvae were collected during nine survey cruises conducted in the south-eastern Brazilian Bight between 23^oS and 30^oS in 1985-91. Of 4846 codlet larvae collected during nine cruises, 99.2% were identified as Bregmaceros canton and only 0.8% were B. athanticus. The two species were more abundant during winter in the neritic region (60–135 m depth). Vertical distribution of codlet larvae was studied using the BIOMOC net, and vertical profiles of temperature/salinity and chlorophyll a concentration were recorded by CTD and fluorescent sonde. Only 9.0% of larvae were collected in the upper 30 m and 91.0% were found deeper (> 40 m). The depths of highest density of larvae bore a close relationship to the subsurface chlorophyll maximum layer. Some B. canton larvae were found in the upper 30 m layer at night, but no larva was found during the day. Water temperatures where B. canton larvae occurred ranged from 16 to 23^oC, but most larvae were found at 18–20^oC and in salinities of 35.5–36.5 psu.     

2种药剂预防山杏花期冻害效果的研究

本文通过对卓资县上高台林场坝底营林区的人工山杏林喷施不同浓度的B9和硼酸溶液,以喷施清水为ck,比较不同处理条件下山杏林的物候、成花和坐果状况,对山杏花期冻害的预防进行研究,结果表明:(1)不同浓度的B9溶液能够推迟山杏开花2d～4d,能有效避免晚霜危害,成花率较ck显著提高,但坐果率效果不显著。(2)不同浓度的硼酸溶液能不同程度的提高山杏的抗逆性,从而提高山杏的成花率和坐果率。(3)喷施硼酸溶液的山杏相对于喷施B9溶液山杏的坐果率更好。     

小波变换和偏微分方程在图像去噪中的应用

应用小波分析方法和偏微分方程方法进行图像处理是一个重要课题。小波变换去除图像噪声时虽然能保持图像的细节信息,但是图像的边缘信息被平滑了。使用偏微分方程对图像去噪,并与使用小波变换去除图像噪声后效果进行比较,实验结果表明:使用偏微分方程对图像去噪在平滑噪声的同时可以使边缘得到保持,应用偏微分方程进行图像去噪是一种有效的工具。