共查询到20条相似文献，搜索用时 31 毫秒
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ZHEN Hai lan 《保鲜与加工》2001,(4):119-122
This paper discusses several drawing problems as solution of intersection points and lines when a straight line intersects plane or conical surface, a plane intersects oblique pyramid and cylindroid and the axial line of normal cylinder has skew intersection with the axial line of cylindroid. 相似文献
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多目标决策灰色投影法在水土保持综合效益评价中的应用 总被引：2，自引：2，他引：0
运用灰色系统理论和矢量投影原理,建立了水土保持综合效益评价多目标决策灰色关联投影模型,旨在探讨多目标决策灰色关联投影法在水土保持综合效益评价中的应用。研究表明,利用多目标决策灰色关联投影法进行水土保持综合效益评价是有效的,具有应用和推广价值。 相似文献
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Quan Yujuan Li Shiguang 《保鲜与加工》1998,(1):77-81
In this paper,a new image reconstruction algorithm named maximum entropy reprojecting is developed for missing projection data from some objects are opaque for parts of ray.The results of comparing simulation experiments on the general computer indicate that the quality of reconstructed images by the new algorithm are much better than the tradional maximum entropy algorithm.So the algorithm has reliable propect in application. 相似文献
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基于DEA方法的中国林业生产效率分析及优化路径 总被引：9，自引：1，他引：8
提高生产效率是实现林业可持续经营的基本要求,也是发展现代林业的关键性工作之一。笔者首先运用DEA分析方法,对中国31个省份的林业投入产出的综合效率值、纯技术效率值、规模效率值和规模效益类型分别进行比较分析,进而对中国各省林业投入产出的投影值进行测算,以此为依据提出提高林业投入产出效率的改进措施。结果显示,天津、山西、广东和贵州4个省份林业投入产出效率达到最优,其余27个省份均存在不同程度的效率损失。这表明中国2006年林业整体效率较低,进一步的分析发现,27个省份的林业投入普遍存在不足,林业总产值有待进一步提高,投入不足制约了这些省份的林业投入产出效率的提高,只有适当改变各省的林业产业结构,提高林业资金的利用水平,才能达到林业的有效投入产出效率。 相似文献
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基于人们对城市滨水绿地景观的关注日益加强,本文提出将RAGA-PPE模型（基于加速遗传算法的投影寻踪等级评价模型）应用到城市滨水绿地景观效果的评价中,将多维数据指标转换成低维子空间,通过寻求最优投影方向来计算投影函数值,建立多元数据分类与评价模型,从而根据投影值的大小进行景观评价。以大庆市为研究对象,构建了大庆市滨水绿地景观效果的评价指标体系及等级标准,并对5个城市滨水绿地的景观效果进行评价。评价结果表明：大庆市东风湖的等级值为1.5561,景观效果较好;万宝湖、滨州湖的等级值分别为3.3425和3.3427,景观效果一般;乘风湖的等级值为3.6491,景观效果较差;黎明湖的等级值为4.7159,景观效果差。评价结果与公众主观感觉基本一致,该模型具有较高的评价精度,适用于城市滨水绿地景观效果的分析评价,避免了传统方法存在的不足,为具有模糊、不确定性高维数据的景观综合评价提供了新的思路与方法。 相似文献
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为了能够对复杂的干旱灾害系统进行灾后评估,反映云南旱灾灾后综合损失,为云南防旱抗旱减灾策略提供理论依据。以云南1950-2009年的旱灾受灾、成灾面积,粮食损失为评价指标,采用投影寻踪法得到分级评估后的综合评价指标。计算结果表明：云南是一个干旱灾害频发且严重的省份,平均2.3年就会出现一次比较严重的旱灾,60年来重大灾害以上发生频次和旱灾损失程度不断上升,给云南经济社会带来了巨大影响,特别是2000年以来的10年期间,发生重大灾害以上次数高达9次,其中重大灾害1次,特大灾害8次。 相似文献
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基于元分析的大豆生育期QTL的整合 总被引：7，自引：0，他引：7
共搜集整理了12年来已经报道的与大豆生育期有关的98个QTL,通过BioMercator2.1和公共标记映射整合到大豆公共遗传连锁图谱soymap2上,并利用元分析技术推断QTL位置,计算提取真正有效的QTL。发掘出大豆两个重要生育时期,共9个“真实QTL”及其连锁标记,其中与开花期(R1)相关的有7个,与成熟期(R8)相关的有2个,建立了QTL的一致性图谱,其中L连锁群上的一个定位区间包含一个已发表的有关R1的基因。在5个连锁群上共发现10个控制多个生育时期的QTL。本研究结果为大豆生育期QTL精细定位和基因克隆奠定了基础。 相似文献
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This paper presents a method which is based on MPI and uses idle distributed computation resource to speed up NC machining program. The experimental results of cutter-location data parallel computation algorithm based on projection method and adaptive projection method show that it scores satisfying speedup. 相似文献
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Guo Yingzhong 《保鲜与加工》1997,(2):87-93
Using basic principles of stereographic projection,block theory and rock mechanics,this paper tries to find a simple and easy method for determination of an optimum scheme for bolting unstable rocks on a rock slope in design of slope engineering.finally, examination and analysis is made of the completed project for bolting the unstable,high and steep rock slope on the campus of Chongqing University. 相似文献
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YE Xiao _ qin 《保鲜与加工》1999,(4):102-105
This paper discusses some questions about the profile line of space geometry,such as the judgement of the parallelism of the two profile lines with the same directions and the visibility about the skew lines and the reappeared points of profile lines, which make the solution of some questions in space geometry more easy than those commonly used. 相似文献
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Techniques of programmable vertex shader and pixel shader have been integrated in newly developed graphics hardware armed with powerful Graphics Processing Unit(GPU) in recent years, and as a result, real-time volume rendering can be implement. First, rendering pipeline, hardware architectures on per-pixel shading and fast rendering principium of the modern programmable GPU are explained in detail. Second,technology on how to analyze and solve volume rendering problems is described. Finally, maximum intensity projection (MIP) method rendering medical volume data have been implemented based on programmable Graphics Processing Unit. In a performance test, spent time rendering medical volume data based on programmable pixel shader in GPU is obviously less than spent time rendering it do without programmable pixel shader. 相似文献
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Zhuo Damin Zhong Minxiu 《保鲜与加工》1988,(4)
Three symmetrical component algorithms are presented in this paper. Walsh algorithm, half-cycle Fourier algorithm and half-cycle Fourier alogrithm of changing correlating functions on the (l,o) plane. And as these algorithms have the advantages of fast respondence, high accuracy and less calculation amount, calculation can be done with a cheap microcomputer. 相似文献
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Hybrid genetic algorithms, which are based on steepest descent algorithm and genetic algorithm, are investigated for the purpose of multimodal optimization. The performances of the hybrid genetic algorithms are evaluated with criteria such as convergence probability, average convergence time and average convergence value of the function in the case of solving global optimization for Schaffer function. It is shown that the performances of the hybrid genetic algorithms are better than steepest decent algorithm or genetic algorithm, and the hybrid genetic algorithm, in which the individuals used for local optimization by steepest decent method are chosen by chance in each generation population, is more efficient than that in which the individuals used for local optimization by steepest descent method are selected from excellent individuals. 相似文献
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This paper studies the problem of computer vision in the vehicle intelligent auxiliary driving system. An effective and real time method in highway to search and track obstacle is presented. Obstacle candidates are tracked and analyzed, false alarms generated by the object detector are recognized and rejected. It also supplies some valuable discussion on problems existing in its experiments. 相似文献
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基于Landsat8遥感影像的地表温度反演方法对比研究 总被引：1，自引：0，他引：1
随着数据的自由共享,Landsat8系列卫星的遥感数据已经成为地表温度反演的重要数据之一。本文基于Landsat8数据的地表温度反演算法,选择大兴安岭地区漠河市作为研究区域。采用基于Landsat8热红外波段的辐射传输模型法、单窗方法、劈窗算法等不同方法对地表温度进行反演,探究高纬度地区地表温度分布规律,并运用野外实测地温数据进行验证。结果表明：针对本研究区的3种地表温度反演的拟合效果都较好,温度误差在1℃左右,其中辐射传输方程法所得结果精度更高,可为高纬度地区夏季地表温度反演与冻土退化等研究提供一定的参考价值。 相似文献
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An improved mean back projection algorithm based on an isopotential back projection algorithm of electrical impedance tomography (EIT) is presented by adopting the mean back projection theory of computer tomography. The distance from the midpoint of an injected electrode pair to the midpoint of a measured electrode pair is taken as approximately the length of the projection routine which is introduced into the back projection process. The positive and negative mean values of relative conductivities obtained by back projection are computed. The final relative conductivities are the differences between the conductivity values obtained by back projection and the corresponding sign mean value. If the results change sign, they are set to zero. Simulations and phantom experiments show that fewer artifacts are present in images reconstructed by mean back projection algorithm than those reconstructed using the back projection algorithm. The improved mean back projection algorithm is more practical and effective than the back projection algorithm. 相似文献