铸造热锻模具钢表面复合强化

研究了Al-C-Ti、Fe-C-Ti、Fe-Al-C-Ti体系热爆反应形成的组织和结构,并结合传统的铸造工艺在铸造模具钢表面形成颗粒增强复合层.研究结果表明：20% Fe-10% Al-C-Ti是较理想的复合体系,其热爆温度低于30% Fe-C-Ti体系,在1 200 ℃热爆反应可充分进行,获得颗粒尺寸为1～2 μm的TiC和少量FeAl.铸造过程中热爆形成的表层增强颗粒与钢发生相互扩散,实现了较好的融合,复合层的厚度达4 mm,硬度得到提高,并呈梯度分布.     

秸秆揉切机用刀片磨损的研究

对9RZ-60型揉切机用刀片进行了磨损试验,探讨了刀片材料、作业对象、装机位置和刃口形式对刀片磨损的影响,对65Mn、T10和Crl2MoV三种材料的刀片磨损表面形貌进行了微观分析,指出加工羊草时,刀片材料为主要影响因素,加工玉米秸和豆秸时,刃口形式为主要影响因素。刀片加工秸秆的磨损形式是以抛光磨损为主,辅之以硬杂质造成的磨料磨损。     

滚珠丝杠的温升及热变形对策

对滚珠丝杠的温升及热变形的对策进行了探讨,提出解决温升和热变形的方法,为滚珠丝杠的设计、安装、使用和维修提供参考.     

滚珠丝杠的温升及热变形对策

对滚珠丝杠的温升及热变形的对策进行了探讨，提出解决温升和热变形的方法，为滚珠丝杠的设计、安装、使用和维修提供参考。     

不同空间粒度下地表水体分布格局多样性研究

选取河南省北部、中部和南部典型研究样区,将空间粒度方法引入并应用于地表水体多样性的研究中。在总结前人研究水体多样性测度方法的基础上,提出新的方法——空间分布长度指数(MSHDLI),并在1 km×1 km网格尺度下研究MSHDLI、水网密度(RD)和空间分布面积指数(MSHDAI)的粒度效应、相关性和相关系数的粒度响应、尺度效应关系及回归模型。结果表明:随着粒度的增加,MSHDLI、RD和MSHDAI的粒度响应曲线均为下降型;MSHDLI与RD和MSHDAI有显著的相关关系,平均相关系数r分别为0.997和0.878(P0.01),且MSHDLI与RD、MSHDAI相关系数的粒度效应属于显著正相关关系;MSHDLI与RD的拟合度函数均是对数函数,MSHDLI与MSHDAI的拟合度函数均是多项式函数;由三者的多元线性回归模型可知MSHDLI与RD、MSHDAI线性相关且对它们的解释程度达到95%以上。MSHDLI可以将RD描述水资源广度和MSHDAI描述水资源空间分布离散性的优势结合起来。     

塔里木盆地地表水化学特征及在人类活动影响下的变化

本文在阐述塔里木盆地地表水化学时空分布规律的基础上，分析近几十年由于人类活动对地表水化学变化的影响。特别是修建大型引水工程和大规模农垦对地表水化学特征有很大影响，其中变化最突出的是塔里木河和博斯腾湖。     

羊草草原对喷施稀土元素的生理生态学反应

稀土元素在农作物中的应用已取得了很好的效果。本文则把稀土元素应用到天然羊草草原上,通过喷施稀土元素的小区试验,调查羊草的株高、叶长、叶宽、鲜重和干重,发现喷施稀土元素能促进羊草的生长,增加植株重量。因此,对羊草草原喷施稀土元素是一条提高草地生产力的有希望途径。     

Cryptosporidia on dairy farms and the role these farms may have in contaminating surface water supplies in the northeastern United States

The prevalence and risk factors for shedding of cryptosporidia by dairy cattle and calves and the prevalence and risk factors for cryptosporidia in surface waters associated with dairy farms were determined for a well-defined watershed in the northeastern United States. Eleven dairy farms were enrolled in the study and subjected to monthly sampling over a 6-month period. Animal-, water-, and manure-management practices were determined by survey and fecal, on-farm water, and stream samples were obtained monthly and evaluated for the presence of cryptosporidia. Ninety-one percent of the dairy farms in our study had Cryptosporidium on their premises. Fifteen percent of the sampled calves 0–3 weeks of age were shedding cryptosporidia. The risk factors for calves shedding cryptosporidia were contact between calves and frequent bedding changes. The probability of shedding cryptosporidia decreased with age. Nine percent of farm-associated stream samples were cryptosporidia-positive. The single risk factor for detecting cryptosporidia in surface water was increasing frequency of spreading of manure on fields. The probability of detecting cryptosporidia in streams decreased as 5-day cumulative precipitation increased. There were no animal-associated or barnyard-management features associated with detecting cryptosporidia in farm-impacted streams.     

一例白鲸应激反应综合症的病例报道

本文就一例幼年雌性白鲸在运输后发生的应激反应综合症进行了诊断、治疗。临床表现为精神不振、拒食、体重下降、体色暗淡、巩膜及结膜充血、皮肤瘙痒;血液学检查表明轻度贫血和脱水、肌肉炎症及胃炎。后进行综合措施调整后,4d后恢复采食,2周后康复。同类鲸的疾病研究国内文献未见报道。     

Combined use of optical and radar satellite data for the detection of tillage and irrigation operations: Case study in Central Morocco

The objective of this study is to present a new application of optical and radar remote sensing with high spatial (∼10 m) and temporal (a few days) resolutions for the detection of tillage and irrigation operations. The analysis was performed for irrigated wheat crops in the semi-arid Tensift/Marrakech plain (Central Morocco) using three FORMOSAT-2 images and two ASAR images acquired within one week at the beginning of the 2005/2006 agricultural season.The approach we developed uses simple mapping algorithms (band thresholding and decision tree) for the characterisation of soil surface states. The first images acquired by FORMOSAT and ASAR were processed to classify fields into three main categories: ploughed (in depth), prepared to be sown (harrowed), and not ploughed-not harrowed. This information was combined with a change detection analysis based on multitemporal images to identify harrowing and irrigation operations which occurred between two satellite observations.The performance of the algorithm was evaluated using data related to land use and agricultural practices collected on 124 fields. The analysis shows that drastic changes of surface states caused by ploughing or irrigation are detected without ambiguity (consistency index of 96%). This study provided evidence that optical and radar data contain complementary information for the detection of agricultural operations at the beginning of agricultural season. This information could be useful in regional decision support systems to refine crop calendars and to improve prediction of crop water needs over large areas.