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1.
要正确对待西部种草   总被引:35,自引:9,他引:26  
西部种草需要正确对待几个问题:良种不是绝对的,与环境协调发展的就是好草种;种草的效益不是单方面的,不是追求单方面的效益;人工草地是现代农业的必要组分,同时不要忽视天然草原;种草不要忽视灌木,清除灌木要慎重;种草要有必要农业投入,应该用好地种草;要以发展动物生产和饲料工业为重点,完善草地农业系统;管理是草业的命脉,应尽早达到草业生产数字化。  相似文献
2.
提出了一个快速的非破坏性叶面积测定方法,即采用数码相机获取叶片的数字图像,用AutoCAD软件计算园林植物叶面积。并与目前常用的网格法、剪纸法和叶面积仪测定法进行比较分析。研究结果表明,该方法特别适合于针叶、小叶类园林植物以及草坪草叶面积的测定。  相似文献
3.
天祝永丰草地资源图的数字化及草畜平衡分析   总被引:6,自引:5,他引:1  
地图输入是地理信息系统的一项重要内容,扫描数字化技术是其发展趋势。试验利用AutoCAD等常见图形处理软件探讨了数字地图的制作步骤,主要分为地图扫描、地图拼接、矢量化、图斑面积计算和地图整饰等;并以天祝永丰草地为例,绘制了天祝永丰草地资源图,根据数字化地图计算出的各类草地面积进行了草畜平衡分析。  相似文献
4.
DIAGNOSTIC ULTRASOUND IMAGING OF SOFT TISSUES IN THE BOVINE DISTAL LIMB   总被引:4,自引:0,他引:4  
In this study sonographic images of healthy flexor tendons, digital flexor tendon sheaths, metacarpophalangeal and metatarsophalangeal joints, and proximal and distal interphalangeal joints of the bovine limb were made. Then, synovial cavities in cadavers were filled with the necessary amount of fluid to make the lumina visible sonographically. After injecting 30–40 ml of saline solution into the digital flexor tendon sheath and into the metacarpophalangeal and metatarsophalangeal joints, or 8 ml in the proximal interphalangeal joint and 10 ml in the distal interphalangeal joint, the pouches of these synovial cavities were clearly demarcated. Afterwards, the sonographic image of synovial cavities distended by various inflammatory content were described. When the sonographic findings were compared to the findings in clinical patients, centesis and intraoperative procedures, there appeared to be a relationship as to the extent and location of the disorders as well as to the nature of the synovial effusion. Finally, we identified which planes on diseased bovine distal limbs were appropriate for obtaining optimal sonographic images.  相似文献
5.
数字影像技术在草坪质量评定中的应用   总被引:3,自引:0,他引:3  
进行草坪质量评定时,草坪的密度、盖度和高度等指标较容易判断,可以用仪器设备进行测量,但也存在一定的模糊性,如草坪色泽和抗逆性等。人为的喜好与认识不同,可能得到不同的评价结果。介绍了数字影像技术评定草坪质量的原理,及其在草坪色泽和盖度等质量评定中的应用。  相似文献
6.
ACQUISITION HARDWARE FOR DIGITAL IMAGING   总被引:2,自引:2,他引:0  
Use of digital radiography is growing rapidly in veterinary medicine. Two basic digital imaging systems are available, computed radiography (CR) and direct digital radiography (DDR). Computed radiographic detectors use a two-step process for image capture and processing. Image capture is by X-ray sensitive phosphors in the image plate. The image plate reader transforms the latent phosphor image to light photons that are converted to an analog electrical signal. An analog to digital converter is used to digitize the electrical signal before computer analysis. Direct digital detectors provide digital data by direct readout after image capture—a reader unnecessary. Types of DDR detectors are flat panel detectors and charge coupled device (CCD) detectors. Flat panel detectors are composed of layers of semiconductors for image capture with transistor and microscopic circuitry embedded in a pixel array. Direct converting flat panel detectors convert incident X-rays directly into electrical charges. Indirect detectors convert X-rays to visible light, then to electrical charges. All flat panel detectors send a digitized electrical signal to a computer using a direct link. Charge coupled device detectors have a small chip similar to those used in digital cameras. A scintillator first converts X-rays to a light signal that is minified by an optical system before reaching the chip. The chip sends a digital signal directly to a computer. Both CR and DDR provide quality diagnostic images. CR is a mature technology while DDR is an emerging technology.  相似文献
7.
DIGITAL IMAGE STORAGE   总被引:2,自引:2,他引:0  
Digital image archival requires less physical storage space, allows for rapid storage and retrieval and avoids loss in image quality over time or with image duplication compared with film storage. Because medical imaging data are critically important and, by law, must be stored in a safe, accessible manner, it is imperative not to have one computer error destroy all copies of the image data. Several options for image storage media are available including magnetic tape, optical media, spinning disks and solid state. Other considerations include on-site vs. off-site storage, redundancy, on-line vs. off-line storage, and removable storage media for disaster recovery. The different storage media can be used in different configurations to provide sufficient protection of digital data. Choose a storage system that will keep your data safe from unauthorized access, hardware failure, and clinic disasters.  相似文献
8.
DIGITAL IMAGE PROCESSING   总被引:2,自引:2,他引:0  
Image processing or digital image manipulation is one of the greatest advantages of digital radiography (DR). Preprocessing depends on the modality and corrects for system irregularities such as differential light detection efficiency, dead pixels, or dark noise. Processing is manipulation of the raw data just after acquisition. It is generally proprietary and specific to the DR vendor but encompasses manipulations such as unsharp mask filtering within two or more spatial frequency bands, histogram sliding and stretching, and gray scale rendition or lookup table application. These processing steps have a profound effect on the final appearance of the radiograph, but they can also lead to artifacts unique to digital systems. Postprocessing refers to manipulation of the final appearance of the radiograph by the end-user and does not involve alteration of the raw data.  相似文献
9.
基于数码照片的草地植被覆盖度快速提取方法   总被引:2,自引:0,他引:2       下载免费PDF全文
胡健波  张璐  黄伟  吴世红  刘长兵 《草业科学》2011,28(9):1661-1665
草地植被覆盖度是草地健康与否的重要参数,提高草地植被覆盖度的计算效率和精度具有重要的意义。本研究提出了一种利用过绿特征植被指数和半自动阈值设定算法(半自动阈值法)的从数码照片中快速计算草地植被覆盖度的方法,并将该方法与最大似然法监督分类方法(最大似然法)和色度饱和度法进行了比较。对32张草地数码照片的植被覆盖度估算结果和准确结果进行回归分析,分别得到斜率、截距和回归系数这3个参数。结果表明,3种方法都未能考虑植物的非绿色组分而存在低估的问题。半自动阈值法的准确度堪比最大似然法,且没有后者存在的低覆盖率高估问题;而且该方法人工干预少,计算结果准确客观,适用性强;但是对绿色特征不明显的植物(如灰绿色植物)效果不佳。  相似文献
10.
应用数字照相机研究西藏草地产草量   总被引:2,自引:0,他引:2  
应用农业数字化照相机(ADC)测定西藏草地干物质(DM)量,并与野外采样测定数据相结合,用植被指数测定草地DM量的估测模型.本次研究为4个主要草地类型(高寒草原、高寒草甸、以西藏嵩草为建群种的高寒草甸以及针茅属草为优势种的高寒草原)建立了DM估测模型(与实际有较好的拟合度).该方法为小尺度的草地研究、动态监测和畜牧业生产提供方便、实用、经济且较准确的方法和技术.  相似文献
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