计算机犬病诊断原理   总被引：1，自引：0，他引：1  

刘孟强  何保荣  刘桂荣  杨宝拴 《农业网络信息》2004,(7):11-13,31

本研究模拟人类专家的诊断过程,对常见犬病用计算机进行诊断模拟,试验建立了犬病诊断的计算机处理系统(QBZD)。本文主要阐述了QBZD系统的结构构成、诊断机理及操作应用  相似文献   

Quantifying patch distribution at multiple spatial scales: Applications to wildlife-habitat models     

Johnson  Chris J.  Boyce  Mark S.  Mulders  Robert  Gunn  Anne  Gau  Rob J.  Cluff  H. Dean  Case  Ray L. 《Landscape Ecology》2004,19(8):869-882

Multiscale analyses are widely employed for wildlife-habitat studies. In most cases, however, each scale is considered discrete and little emphasis is placed on incorporating or measuring the responses of wildlife to resources across multiple scales. We modeled the responses of three Arctic wildlife species to vegetative resources distributed at two spatial scales: patches and collections of patches aggregated across a regional area. We defined a patch as a single or homogeneous collection of pixels representing 1 of 10 unique vegetation types. We employed a spatial pattern technique, three-term local quadrat variance, to quantify the distribution of patches at a larger regional scale. We used the distance at which the variance for each of 10 vegetation types peaked to define a moving window for calculating the density of patches. When measures of vegetation patch and density were applied to resource selection functions, the most parsimonious models for wolves and grizzly bears included covariates recorded at both scales. Seasonal resource selection by caribou was best described using a model consisting of only regional scale covariates. Our results suggest that for some species and environments simple patch-scale models may not capture the full range of spatial variation in resources to which wildlife may respond. For mobile animals that range across heterogeneous areas we recommend selection models that integrate resources occurring at a number of spatial scales. Patch density is a simple technique for representing such higher-order spatial patterns.  相似文献   

新生仔猪的护理——以上海某规模猪场为例     

石保玉  张振玲 《猪业科学》2020,37(10):114-116

我国养猪业发展迅速，整体水平在不断提高，但是与养殖业较为发达的国家相比仍有一些差距。以每年每头母猪断奶的仔猪数（PSY）为例，目前国外养猪发达国家PSY普遍已超30头，而我国却仍在25头左右，仍有较大的提升空间。仔猪护理工作在生猪生产过程中尤为重要，一旦护理措施不当就会造成仔猪死亡，从而降低PSY，直接影响到养猪企业的经济效益。规模猪场仔猪死亡的主要原因就是由于仔猪护理不当所引起的，仔猪护理问题一直是养猪业的一个难题。文内以2020年4—5月上海某规模猪场某栋产房新生仔猪（共477头，其中压死8头，瘦弱致死12头，腹泻致死亡的32头）为例，介绍规模猪场的仔猪护理及注意事项，以期为仔猪护理工作提供借鉴。  相似文献   

乡镇污水处理厂运行管理相关问题探讨   总被引：1，自引：0，他引：1  

王星  贺建 《安徽农业科学》2014,(2):522-522,551

乡镇污水处理厂作为环保基础设施建设的重点,普遍存在重建设轻运营的问题。笔者结合重庆市实际情况,重点分析了乡镇污水处理厂运行管理中存在的问题,并有针对性地提出了建议,包括提高收集率、完善末端工艺、专业化运营、改变考核体系、优化污泥处置、加强再生利用和远程在线监控等。  相似文献   

规模化奶牛场经营管理研究     

郑国生  黄仕伟 《中国奶牛》2012,(18):19-22

进入21世纪以来,中国奶业步入了快速发展期,规模化奶牛场经营管理的科学研究已经成为每个奶牛场经营管理者的必修课程和首要任务。本文对规模化奶牛场经营管理效能的相关影响因子进行了系统的综述,分析了规模化奶牛场经营管理的国内外研究现状、取得的成果以及存在的不足,并对未来我国规模化奶牛场经营管理的研究方向进行了展望。  相似文献   

滚珠丝杠的温升及热变形对策     

于旭年  荆福义 《农业装备与车辆工程》2005,(11):40

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.  相似文献   

滚珠丝杠的温升及热变形对策   总被引：1，自引：0，他引：1  

于旭年  荆福义 《农业装备与车辆工程》2005,(3):40-40,44

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。  相似文献   

基于可变移动窗口方法估算太湖泥沙环流运动的本征尺度     

陈军  王保军  付军  高晓军 《水生态学杂志》2011,32(5):1-5

基于遥感反演获得的太湖悬浮泥沙浓度数据,利用移动窗口方法,分析探讨了平均局部方差和移动窗口尺寸的关系。在90～1 860 m移动窗口尺寸变化范围内,太湖悬浮泥沙浓度的平均局部方差随着移动窗口尺寸的增大而增大,且抛物线模型能较好的描述2者的关系,回归系数0.9959。通过对抛物线模型求最大值可知,局部方差最大值所对应的移动窗口尺寸为2 308.33 m,根据当时的风速和风向,考虑泥沙浓度空间分布与水体运动之间的相关性,该尺寸可以解释为太湖逆时针环流的本征尺度。  相似文献   

Comparing fire spread algorithms using equivalence testing and neutral landscape models     

Brian R. Miranda  Brian R. Sturtevant  Jian Yang  Eric J. Gustafson 《Landscape Ecology》2009,24(5):587-598

We demonstrate a method to evaluate the degree to which a meta-model approximates spatial disturbance processes represented by a more detailed model across a range of landscape conditions, using neutral landscapes and equivalence testing. We illustrate this approach by comparing burn patterns produced by a relatively simple fire spread algorithm with those generated by a more detailed fire behavior model from which the simpler algorithm was derived. Equivalence testing allows objective comparisons of the output of simple and complex models, to determine if the results are significantly similar. Neutral landscape models represent a range of landscape conditions that the model may encounter, allowing evaluation of the sensitivity and behavior of the model to different landscape compositions and configurations. We first tested the model for universal applicability, then narrowed the testing to assess the practical domain of applicability. As a whole, the calibrated simple model passed the test for significant equivalence using the 25% threshold. When applied to a range of landscape conditions different from the calibration scenarios, the model failed the tests for equivalence. Although our particular model failed the tests, the neutral landscape models were helpful in determining an appropriate domain of applicability and in assessing the model sensitivity to landscape changes. Equivalence testing provides an effective method for model comparison, and coupled with neutral landscapes, our approach provides an objective way to assess the domain of applicability of a spatial model.  相似文献   

The impact of thematic resolution on the patch-mosaic model of natural landscapes   总被引：1，自引：1，他引：0  

Guillermo Castilla  Kerry Larkin  Julia Linke  Geoffrey J. Hay 《Landscape Ecology》2009,24(1):15-23

We argue that thematic resolution, i.e., the level of categorical detail of a thematic map expressed by the number of classes included in the map legend, is an inherent component of the scale at which a landscape is analyzed. Changing the number of classes can change the configuration of the patch mosaic as much as changing the grain does. We address recent calls in this and other journals to deepen research in this topic. In particular, we report how thematic resolution affects the patchiness of mosaics representing natural landscapes, which have seldom been studied in this respect. We selected seven 50 × 50 km landscapes within national parks, each representative of a world biome. We applied an object-based unsupervised classification to Landsat TM imagery of these landscapes using increasing numbers of classes, between 2 and 50, and derived curves of mean patch size and patch density for each site. Our results are consistent with previous findings in that the patchiness of output mosaics increases monotonically with increasing thematic resolution, with a higher rate of increase up to eight classes that declines until it becomes roughly constant for more than 16 classes. However, this constant rate of increase is still considerable, meaning that, at least for natural landscapes, there is no threshold beyond which the patch-mosaic model is independent of the conceptual filter applied. This dependence on human fiat calls for re-thinking the patch-mosaic paradigm.  相似文献