计算机三维实体造型在工程设计中的应用

计算机绘图技术的发展和计算机性能的不断提高，引发了工程设计的新理念，三维实体造型设计也应运而生，并以其无可比拟的优越性显示出强大的生命力。AutoCAD、Pro／E和3DMAX等绘图软件不仅可以较方便地绘制二维视图，还可以形象逼真地绘制_三维视图。利用这些软件的强大功能，对图形进行适时修改、动画控制和模拟生产过程，使计算机三维实体绘图成为越来越方便的方法。为此，论述了三维实体建模的优点．介绍了三维实体建模的思路和特点．以及采用三维实体建模对传统设计方法的影响。     

UG技术在扭曲叶片三维造型中的应用

扭曲叶片广泛应用于中高比转速叶轮,本文以UG技术对扭曲叶片进行了造型,从而有助于设计人员及时、直观地发现叶片的水力特性和机械特性。可以看出,将UG技术引入叶片水力设计领域,将对提高叶片性能产生积极的重要影响。     

改进加权FCM用于裂纹蛋2D图像分割的研究

解决裂纹鸡蛋图像灰度直方图目标与背景区域分布模糊、图像分割效果差的问题.通过将包含空间信息的二维直方图和改进特征加权FCM算法有机结合,迭代寻求最佳聚类有效性函数和加权矩阵,实现鸡蛋图像缺陷分割.同时,对经典FCM和改进特征加权FCM算法的性能进行了分析比较.结果表明:提出的算法更接近于真实聚类中心,目标函数值亦得到改善;二维直方图的改进特征加权模糊聚类算法更好地提取了裂纹鸡蛋图像的细节信息,图像分割效果好.     

小车避障双目视觉识别系统的研发

For the reasons of the complex working environment and plenty of obstacles in facility agriculture, this paper studied the problem of identifying the obstacles by binocular vision recognition system.Binocular vision system was built up at first.OpenCV and Matlab were used for the binocular camera calibration respectively.Secondly, Bouguet algorithm was used to rectify the input images and analyse three kinds of matching algorithms.Then the smallest enclosing moment of the object could be extracted.At last, the distance between the objects was calculated and 3D reconstruction was used.The experimental results showed that the binocular vision system had high reliability, high real time, strong anti-interference ability and lower cost which can identify different obstacles with a wide application rage.It could satisfy the operational requirements of the unmanned control vehicle’s automatic obstacle avoidance in facility agriculture, and laid the foundation for vehicle obstacle avoidance and navigation.     

Zinc and Amino-Acids on the Yield and Nutritional State of Alfalfa Grown in the Tropical Soil

Zinc (Zn) deficiency is common among crops grown in the tropics in acid and weathered soils. In response, the use of amino-acids (AAs) to increase the uptake of this nutrient has been increasing dramatically in recent years. Nevertheless, there is a scarcity of results reported on the effect of applying AAs and adequate quantities of Zn on alfalfa grown under tropical edaphoclimatic conditions. Therefore, a greenhouse experiment was conducted with a completely randomized block in a factorial scheme (4×2) of four Zn rates of 0, 4, 8, and 16 mg kg^?1) with and without spraying of AAs during the sprouting phase, to study the effects on the shoot dry weight (SDW) yield, nutritional state, physiological parameters, and soil fertility. The harvests were repeated over time (three cuts). The SDW yield was significantly influenced up to a rate of 4.0 mg kg^?1 of Zn, after which it stabilized. Independent of the Zn rate, the application of AAs did not influence the SDW yield. Based on the averages for the three cuts, only the Zn rates altered the photosynthesis and chlorophyll content, with no effect of the AAs. The concentrations of Zn in the soil extracted by the Mehlich 1 and diethylenetraminepenta acetic acid (DTPA)- triethanolamine (TEA) methods were strongly and significantly correlated (r = 0.99, P ≤ 0.05) with the Zn rates and the Zn concentrations in the plant tissue. The agronomic, physiological, and zinc use efficiencies diminished with increased Zn rates, while the inverse occurred with the Zn efficiency index.     

Comparison of paddy soil fertility under conventional rice straw application versus cow dung compost application in mixed crop–livestock systems in a cold temperate region of Japan

ABSTRACT

After the rice harvest in Japan, rice straw (RS) is usually cut by combine harvester and incorporated into the soil to improve its fertility. In mixed crop–livestock systems, however, RS is collected and used as livestock feed, and cow dung compost (CDC) is then applied to the soil. This system utilizes the residual organic matter from both rice production and livestock husbandry to make each product. CDC application is also considered to improve the fertility of paddy soil. However, the nutrient input from CDC and the effect of CDC application on soil fertility vary among regions and/or soil types. We compared soil fertility between RS application (RS treatment, avg. 32 years) and RS removal plus CDC application (CDC treatment, avg. 21 years) in 79 paddy fields in Mamurogawa town, Yamagata Prefecture, a cold temperate region of Japan, and measured the nutrient contents in the applied RS and CDC. The total C content of RS was significantly higher than that of CDC, whereas the N, P, K, and Si contents of CDC were significantly higher than those of RS. However, there was no significant difference in paddy soil fertility – as measured by soil organic C, total N, CEC, available N, P, and Si, exchangeable K, Ca, and Mg, base saturation percentage, pH, and bulk density – between the treatments. The soil fertility of most fields was adequate by RS or CDC treatment. Thus, leaving RS in paddy fields or removing it and then adding CDC to the paddy fields has a similar effect in maintaining adequate soil fertility for single rice production or rice–livestock production systems.     

Genetic mapping of the genes for glaucous leaf and tough rachis in Aegilops tauschii, the D-genome progenitor of wheat

Glaucous leaf and tough rachis phenotypes are rare in Aegilops tauschii, the D genome donor to common wheat (Triticum aestivum). The genes for glaucous leaf and tough rachis were mapped using microsatellite probes in A. tauschii. The glaucous phenotype was suppressed by the inhibitor W2^I located on chromosome 2DS. The gene W2^I was mapped to the distal part of 2DS, and was unlinked to the centromere. This suggests that the distance of the W2^I locus from the centromere was maintained during the evolution of hexaploid wheat from its diploid progenitors as the inhibitor gene is at the same position in A. tauschii and bread wheat. The Br^t (Brittle rachis of A. tauschii) locus was located on the short arm of chromosome 3D, and was 19.7 cM from the centromeric marker, Xgdm72.3D. Br^t causes breakage of the spike at the nodes, thus creating barrel-shaped spikelets, while Br₁ in hexaploid wheat causes breakage above the junction of the rachilla with the rachis such that a fragment of rachis is attached below each spikelet.     

Rice R & D Thrusts in the Philippines

1THEPHILIPPINERICESITUA TIONDuringthelastdecade (1991- 2 0 0 0 ) ,annualgrowthin productionslightlyimprovedto 2 3%from 2 2 %duringthepreviousdecade (1981-1990 ) .Duringthelastdecade (1991- 2 0 0 0 ) ,annu algrowthinproductionslightlyimprovedto 2 3%from 2 2 %duringthe previousdecade (1981-1990 ) .Notwithstandingthesteadyincreaseinriceproduction ,thecountryremainedanetriceim porter .In 2 0 0 1,palay (paddy) productioninthecountryhit 12 95Mmtoraround 9 11Mmtofrice .However,inthes…     

Anatomy of a dinosaur—Clarification of vertebrae in vertebrate anatomy

The flat-end surfaces of dinosaur vertebral centra led to the presumption that intervertebral discs occupied the space between their vertebrae. A set of fused hadrosaur vertebrae allowed that hypothesis to be tested. The Tyrannosaurus rex responsible for this pathology did not escape unscathed. It left behind a tooth crown that had fractured. Fragments of that tooth were scattered through the intervertebral space, evidencing that there was no solid structure to impede its movement. That eliminates the possibility of an intervertebral disc and instead proves the presence of an articular space, similar to that in modern reptiles, but at variance to what is noted in birds. While avian cervical vertebral centra appear to be separated by diarthrodial joints, the preponderance of their thoracic vertebral centra is not separated by synovial joints.