热轧工作辊失效原因分析

主要分析了热轧过程温度及轧制力对工作辊寿命的影响.指出提高工作辊使用寿命的几种措施.     

NiTi形状记忆合金的加工方法

对NiTi形状记忆合金的多种加工方法如锻造、热挤压、轧制和拉拔、冷加工、粉末成形、包套碎片挤压成形、溅射沉积加工等进行了详细介绍。     

管材压扁的回弹分析

应用材料力学中的单位力法求回弹值的新理论，对管材压扁工艺的回弹量进行了分析计算，理论得出的结果与实际相符，可用于管材压扁中回弹量的计算预报。     

PIXGRO: A model for simulating the ecosystem CO2 exchange and growth of spring barley

A model, PIXGRO, developed by coupling a canopy flux sub-model (PROXEL_NEE; PROcess-based piXEL Net Ecosystem CO₂ Exchange) to a vegetation structure submodel (CGRO), for simulating both net ecosystem CO₂ exchange (NEE) and growth of spring barley is described. PIXGRO is an extension of the stand-level CO₂ and H₂O-flux model PROXEL_NEE, that simulates the NEE on a process basis, but goes further to include the dry matter production, partitioning, and crop development for spring barley. Dry matter partitioned to the leaf was converted to leaf area index (LAI) using relationships for the specific leaf area (SLA). The canopy flux component, PROXEL_NEE was calibrated using information from the literature on C3 plants and was tested using CO₂ flux data from an eddy-covariance (EC) method in Finland with long-term observations. The growth component (CGRO) was calibrated using data from the literature on spring barley as well as data from the Finland site. It was then validated against field data from two sites in Germany and partly via the use of MODIS remotely sensed LAI from the Finland site.Both the diurnal and the seasonal patterns of gross CO₂ uptake were very well simulated (R² = 0.92). A slight seasonal bias may be attributed to leaf ageing. Crop growth was also well simulated; simulated dry matter agreed with field observed data from Germany (R² = 0.90). For LAI, the agreement between the simulated and observed was good (R² = 0.80), giving an indication that functions describing the conversion of fixed CO₂ to dry matter and the subsequent partitioning leaf dry matter and LAI simulation were robust and provided reliable estimates.The MODIS LAI at a resolution of 1000 m agreed poorly (R² = 0.45) with the PIXGRO simulated LAI and the observed LAI at the Finland site in 2001. We attributed this to the coarse resolution of the image and/or the small size of the barley field (about 17 ha or 0.25 km²) at the Finland site. By deriving a regression relation between the observed LAI and NDVI from a higher resolution MODIS (500 m resolution), the MODIS-recalculated LAI agreed better with the PIXGRO-simulated LAI (R² = 0.86).PIXGRO provides a prototype model bridging the disciplines of plant physiology, crop modeling and remote sensing, for use in a spatial context in evaluating carbon balances and plant growth at stand level, landscape, regional, and with some care, continental scales. Since almost 50% of the European land surface is covered by crops, such a model is needed for the dynamic estimation of LAI and NEE of croplands.     

西蒙得木对金沙江干热河谷生态保护的作用

金沙江干热河谷生态条件恶劣，水土流失严重，对长江流域中下游特别是三峡大坝存在着极大的负面影响。治理长江流域，保护三峡大坝的重要源头是金沙江干热河谷的生态环境建设。西蒙得木生长的生态环境与金沙江干热河谷的生态环境非常相似，并且西蒙得木具有极高的经济价值，因此在金沙江干热河谷种植西蒙得木，既能改良生态环境，又能发展当地经济。     

Which regional features of Danish agriculture favour the corn bunting in the contemporary farming landscape?

Corn buntings Miliaria calandra were abundant throughout arable agricultural landscapes in Europe, but have catastrophically declined since the mid 1970s with changes in farming practice and now give serious conservation cause for concern. Corn buntings declined in Denmark during 1976–1993, but (almost unique in Europe) have since increased (by up to 11% per annum) in some areas without specific conservation recovery actions. Based on breeding bird surveys in the mid 1990s, highest corn bunting densities occurred on mixed agriculture in west Denmark (Jylland); the species was rarer or absent in regions of highest arable land cover. Corn bunting density and extent of rotational and permanent grassland were correlated, but not with spring sown barley (all known to constitute important corn bunting winter habitat). The extent of spring barley rapidly declined in Denmark during the 1980s, but since 1990, most counties have since shown 2–3% annual increases in this crop, except in Nordjylland, where high densities of corn buntings have remained stable. Elsewhere in Jylland, corn buntings have increased in counties supporting highest densities during the mid 1990s, contrasting stable or declining trends in south and east Denmark where densities were originally lower. After dramatic decreases everywhere in Denmark, corn buntings retain highest breeding densities associated with mixed agriculture, especially where grassland and spring sown barley remained in greatest extent. Although purely based on land use correlation and bird surveillance, these results show an association between mixed farming and favourable conservation status of a species now red-listed throughout much of Europe. Further investigations of habitat use at small spatial scales and throughout the annual cycle are urgently required to better enlighten specific recommendations for wider applicability of guidelines for corn bunting recovery actions elsewhere.     

Distribution and sources of solvent extractable organic compounds in PM2:5 during 2007 Chinese Spring Festival in Beijing

The solvent extractable organic compounds (SEOC), including n-alkanes, polycylic aromatic hydrocarbons, fatty acids, anddicarboxylic acids in PM2.5 during the 2007 Chinese Spring Festival in Beijing, were measured via gas chromatography-massspectrometry for determining the characteristics and sources of these organic pollutants. The concentrations of total n-alkanes, PAHs,and organic acids before Chinese Spring Festival Eve (1025.5, 95.9, and 543.3 ng/m3, respectively) were higher than those after (536.6,58...     

龙子祠泉域地下水金属元素分布特征及健康风险评价

龙子祠泉是临汾市工农业和城市生活的重要水源,随着公众环境健康意识提高,地下水金属元素健康风险研究显得尤为必要.对龙子祠泉域内43个地下水样品中10种金属元素（As、Cd、Hg、Al、Pb、Co、Mn、Fe、Cu和Ni）进行检测和分析,运用多元统计分析方法和健康风险评价模型研究了地下水中10种金属元素分布特征及其暴露的健康风险.结果表明,研究区地下水中金属元素平均浓度由高到低分别为Fe、Al、Mn、Ni、As、Cu、Co、Pb、Hg和Cd,其中Al、Mn、Fe和As超出地下水质量标准（GB/T 14848-2017）Ⅲ类水标准限值.从泉域内不同地下水类型角度看,岩溶泉水水质较好,均达到了生活饮用水的标准;矿坑排水金属超标率（60%）最高,水质最差.多元统计结果表明,Pb、Ni、Co、Cd、Mn和Cu这6种元素主要受到地球化学背景的影响,Al、Fe、Hg和As主要是在山西特有的地质背景下,与人类矿业开采活动密切相关.健康风险评价表明,研究区内不同类型地下水中金属元素通过饮水途径和皮肤入渗途径对成人和儿童暴露的年均总健康风险排序均为：岩溶井>非岩溶泉>非岩溶井>岩溶泉,健康风险主要源于饮用水途径,经皮肤入渗暴露的健康风险不会对人体造成明显危害.泉域地下水中As是引起最大健康风险的金属元素,在水资源利用时应该给予重点管控,尤其在儿童饮水方面.     

2018年春节期间京津冀及周边区域空气质量分析

分析了2018年春节期间京津冀及周边区域空气质量状况,结果表明,京津冀及周边区域2018年春节期间空气污染较重,以石家庄、邢台、邯郸、晋城、长治为中心的区域污染最重,此次重污染过程呈污染范围大、持续时间长的特点。受微风、高湿、逆温等不利气象条件影响,颗粒物污染不断积累和二次转化。除夕(2月15日)至初六(2月21日),北京首要污染源为机动车尾气源,张家口、保定、太原、郑州为燃煤源,太原和廊坊烟花源占比高于其他城市。自除夕(2月15日)下午开始,区域内各城市烟花爆竹燃放相关离子浓度有不同程度的增加,北京、保定烟花源贡献率与贡献浓度与2017年春节期间相比有所下降。2018年春节期间PM_2.5浓度明显高于2015—2017年,区域南部空气质量较差,重污染区域主要集中在以石家庄、邢台、邯郸、长治、晋城为中心的区域。     

Structure-related distribution of PCDD/Fs, PCBs and HCB in a river-sea system

Water concentrations of PCDD/Fs, HCB, and non-ortho, mono-ortho, and non-dioxin-like PCBs were measured four times during 1 year in a coastal area of the Baltic Sea, to investigate background levels and distribution behaviour. Sampling sites included two rivers, an estuary, and the sea. Particulate and apparently dissolved concentrations were determined using active sampling (filters + PUFs), while freely dissolved concentrations were determined using passive sampling (POM-samplers). The distribution between particulate + colloidal and freely dissolved phases, in the form of TOC-normalized distribution ratios (K_TOC), was found to be near or at equilibrium. The observed K_TOC were not significantly different between sampling sites or seasons. For PCDD/Fs, the concentrations were significantly correlated to suspended particulate matter (SPM), while no correlation to organic carbon (TOC) was observed. In the estuary and the sea, PCB concentrations were correlated to TOC. The sorption of various congeners to SPM and TOC appeared to be related to both hydrophobicity and 3D-structure. The PCDD/F concentration in the sea decreased to one third in May, likely connected to the increased vertical flux of particles during the spring bloom.