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1.
室内土壤滴浇法测定了苯磺隆、苄嘧磺隆对不同小麦品种的安全性和叶绿素含量的变化,结果表明:两种药剂对不同小麦品种的安全性存在较大差异,且对根长的抑制作用明显大于株高;对叶绿素含量的影响与对株高的影响结果一致。苯磺隆对周麦13的根和芽敏感,使用不当易产生药害;对偃师4110根长最安全,株高最敏感。苄嘧磺隆对高优503根长最安全,株高最敏感;对周麦13株高最安全,根长最敏感。因此,小麦田化学除草应根据不同小麦品种来选择除草剂品种、有效用量和最佳施药方法。  相似文献   

2.
油茶气象影响指标研究综述   总被引:2,自引:0,他引:2  
基于收集到的近百篇与气象条件有关的油茶研究文献和出版书籍,进行气象条件对油茶生产影响的归类统计,其结果可分为3类,即油茶种植气候适宜性指标、油茶产量气象条件的影响指标、油茶气象灾害指标。油茶种植气候适宜性指标及条件为:(1)年平均气温14~21℃,最适宜温度为16~21℃,极端最低气温-10℃,极端最高气温40℃,最冷月平均气温0℃以上,最热月平均气温31℃以下,年无霜期大于200天,≥10℃积温为4000~7000℃·d,最适宜的≥10℃积温为5000~7000℃·d;(2)年降水量1000~ 2200 mm,最适宜年降水量为1200~1800 mm;相对湿度74%~85%;(3)年日照时数1500~2200 h,年日照百分率35%以上。油茶产量适宜性气象指标及条件为:(1)春梢生长期适宜的平均气温为10~20℃;(2)花芽分化期适宜的平均气温为24~33℃,最适宜平均气温为27~33℃,日平均日照时数在10 h以上;花期适宜的平均气温为10~20℃,最适宜平均气温为14~18℃,盛花期雨日小于13天,日照大于100 h;(3)果实生长期适宜的平均气温为25~30℃,降水量在200 mm以上,最适宜降水量为450~550 mm;(4)油脂累积期适宜的平均气温为16~23℃,降水量在100 mm以上,最适宜降水量为150~200 mm,高温日数小于20天。油茶主要气象灾害有:低温冷冻害、连阴雨、高温干旱、冰雹和大风。  相似文献   

3.
印楝素强化浸提试验研究   总被引:1,自引:0,他引:1  
印楝素为热敏性差的物质,印楝种子含油率高达20%,需在低温和强化条件下浸出。试验表明,浸前是否榨油对印楝浸出速度无明显影响,在超声波强化浸出条件下,40min的浸出率相当于常规2h的浸出率。若浸出时间都为2h,应用超声波强化浸出印楝素的浸出率高达95%,而常规浸出印楝素的浸出率只有84%,超声波强化浸出的效果非常显著。  相似文献   

4.
It is possible to get high compression rate for the interrelationship between neighboring frames of moving pictures. The kernel of research on video compression is that the efficient image compression algorithm is adopted while the interrelationship between neighboring frames and time consumption is concerned to improve the compression efficiency. It is significant that motion compensation is applied to video compression, nevertheless it is too time consuming. A vector coding method based on wavelet transform is presented to avoid searching procedure of motion compensation. Simulation shows that high compression rate is achieved with less time consumption.  相似文献   

5.
冀西北高原不同植被的土壤水分动态变化研究   总被引:1,自引:1,他引:1  
冀西北高原为高寒半干旱地区,降水是此地区土壤水分的唯一给源,研究土壤水分的动态变化对高效利用降雨有至关重要的作用。研究采用定点观测的方法,对不同植被土壤含水量的动态变化进行了比较研究。结果表明,3种植被生长期内不同土层土壤水分变化存在差异。生长前期,3种植被0 ̄30cm土层土壤含水量,农田耕翻地最高,水分条件最好,人工草地与退耕还林地互有高低,30 ̄60cm土层退耕还林地最高,人工草地最少。生长前期,农田耕翻地表层土壤水分较好,能满足春季作物生长要求。生长中期,0 ̄30cm土层农田耕翻地最低,人工草地与退耕还林地互有高低。30 ̄60cm土层农田耕翻地最高,人工草地最低。生长后期,0 ̄60cm土层农田耕翻地土壤含水量最高;人工草地土壤含水量与退耕还林地相比较,0 ̄40cm土层差异不大,40 ̄60cm土层退耕还林地高于人工草地。  相似文献   

6.
A new idea "Pretreatment and cycle stream of control" and the scheme to put it into practice is presented. In space region,the circuit is designed to form chain and cycle,and in time region,the program is designed to distinguish the period and the instant.It is ensured that the pretreatment will be finished in the period and there is always a circuit to wait to the triggered at the instant. So the respond speed of the system is almost approximate to that one of trigger circuit.  相似文献   

7.
采用浸渍法制备CaO/MgO固体碱催化剂,并应用于菜籽油与甲醇的酯交换反应制备生物柴油。考察了镁钙比对CaO/MgO催化活性的影响。试验表明,用质量分数22.6%的乙酸钙浸渍MgO,镁钙摩尔比为3~4时最接近等体积浸渍,镁钙摩尔比为1~2时为过量浸渍。镁钙摩尔比越低,催化剂活性越高,但镁钙摩尔比低于3时,催化剂活性组分分布不均匀,且活性增加不明显。所以最佳镁钙摩尔比为3~4。  相似文献   

8.
A model of credit quantitative measurement and management widely used in foreign countries is introduced, and its limitation which appears while the model is used in China is analyzed. According to the chaos time serials constituted by various period credit grades' transition probability of an enterprise and the average value of its ratio of callback due to breach of faith, applying the theory of the chaos time serials and the local prediction method, a credit grades' transition matrix and a matrix of the average ratio of callback due to breach of faith is established. Which is applied to Chinese enterprises. Thus, a credit risk quantitative measurement and management model which is adapted to commercial bank is established, which is important in theory and practice.  相似文献   

9.
逐日降水量的模拟及其在作物气候风险分析中的应用   总被引:3,自引:0,他引:3  
利用天气发生器(NCC/RCG_WG)模拟了安阳200年的逐日降水序列,并通过对模拟结果与1961-2000年实测资料的对比分析表明,模拟结果的均值及概率分布与实际值接近,可用于进一步对降水资源与风险进行分析。对棉花与降水关系的分析表明,华北地区棉花生长季降水满足程度较高,平均能满足棉花生长需要。生育初期的6月干旱出现的机率大,7月和8月水分满足程度高但也有少数年份会出现干旱或者涝渍,9月和10月以干旱为主。对于小麦生产,华北地区降水规律与小麦需求不匹配,除10月和11月基本能够满足外,其余各月均不能满足需要,且缺水严重,生长季降水只能满足小麦需水量的1/3,生长关键期的4月和5月的降水量只能满足需水量的20%~25%。华北地区的小麦生产生长季缺水,按目前的播种面积,华北地区小麦生长季年均麦田缺水300亿m3以上。  相似文献   

10.
Base on the existing step-by-step structural damage diagnosis method, a three-step structural damage diagnosis method is developed. According to the analysis of the characteristic of genetic algorithm, a new idea of excluding the undamaged element by means of step-by-step evaluation is developed to deal with the damage diagnosis problem. In this method, sensitivity genetic algorithm is used to exclude the undamaged element step by step and residual force method is used to fix the damage district. According to the simulation research of a 2D framed structure, it is shown that the step-by-step structural damage diagnosis method can gain the ideal results when it's difficult for a single damage diagnosis method to get the good results. It is also indicated that sensitivity genetic algorithm is a good way to exclude the undamaged element step by step.  相似文献   

11.
The method to polygon' intersection is applied in computational geometry, computer graphics, GIS, evaluation of geo-hazards and civil engineering. Based on the node state of polygon, the authors propose the method and algorithm of polygon' intersection, the key to which is node operation. This method's concept is simple; and it is easy to computer program's implementation. It avoids to singular problem of Boolean Operation, and is easy to solve the problem of overlapping side and sides intersecting in node of polygon. For the arbitrary way of intersecting of arbitrary solid polygon, this method is accurate and general.  相似文献   

12.
In the smart bar-beam structure with piezoelectric strain actuator active control function to vibration, the thickness effect of paste layer is considered and strain is assumed linear distribution along the thickness direction of each layer. The piezoelectric actuator point force model of Crawley and Luis is refined, a more general point force model is established to the smart beam with strain actuator. Point force model calculation formula is educed to smart beam with two-side symmetry paste actuator or one-side paste actuator. The computer simulation is done and the result reveals modified point model is right. The modified model is more common, as is important to design piezoelectric smart structure.  相似文献   

13.
The 2D motif method is a surface characterization method promising to separate roughness and waviness from a profile and is adopted by ISO,so is meaningful to extend this method to 3D.Vincent's watershed algorithm is employed for the generation of 3D-motif.A smallest area selecting criteria is proposed for the use of clearing the small motifs which are concerned as noise.As there are no manipulating factors as 2D-method,a multi-scale analysis is employed based on area and depth criteria,the use of depth criteria is to prevent the combination of two adjacent motifs if there is a significant peak on the border of them.Finally the surface of C(100) are analyzed by the presented method,the texture of this surface has been characterized.  相似文献   

14.
The structure of liquid mercury is determined by 0 -20 type powder diffractometer. A new simple method is proposed to analy the structure of non-atom liquid by using the intensity diffraction profiles. It is found that the space between two nearest neighbor Hg atoms is 3.00 A and the second near neighbor atoms is 3.38 A. The method of peak separation for X-ray diffraction profile is proved to be effective by applying to non-atom liquid system.  相似文献   

15.
A novel scheme is present to improve the conversion accuracy of ADC. The proposed approach uses adaptive sinusoidal filter. For the measurement of the signal with given frequency, the automatic adjustment of filter coefficients is based on least mean-square error rule, which is a mathematical tool can be employed to make filter output signal achieve the best approximation to the needed one. Then based on the result, it is able to get the amplitude and phase of the measured signal accurately. MATLAB software is used to verify the effectiveness of the algorithm. It proves that adaptive filter has improved the accuracy and signal-to-noise ratio of ADC, which is equal to increase the conversion digits.  相似文献   

16.
Secondary Voltage Control is a new way of voltage control,firstly the power system is divided into many control areas whose electric distance is remote.The partitioning method of secondary voltage control is studied and an algorithm that combination of the threshold search and dynamic scatter is presented.That is,the initial grouping scheme is obtained by searching the threshold value.The dynamic scatter method then is used to regulate and improve the initial results.The method is based on system's physical character,it's unnecessary to modify the network's model and analysis the eigenvalue,so the compute rate is fast.Through comparing the method and the traditional methods,this method is proved to be a reasonable and feasible partitioning scheme.  相似文献   

17.
Grounding grids are the guarantee of substation running safety. The fault of grounding grids is a threat to people and equipment in substations. A method to diagnose the fault of grounding grids based on magnetic field inverse problem. The inverse problem of magnetic field is established by injecting and extracting a low frequency current. The morbid of inverse problem is solved through regularization and Newton iteration method to obtain the distribution of the mesh currents. The approximate distribution of the magnetic field is calculated to diagnose the fault of the grounding grid. A 4×4 substation grounding grids is taken as an example. By comparison of the forward problem result, the error is under 3%, so the prposed method of inverse problem is verified. The selection of measurement point is discussed, and 40% of the number of meshes is accounted to approximate the real distribution of the magnetic field on the grounding grids.  相似文献   

18.
研究表明,仙游县为农区鼠害重发区,田间优势种为黄毛鼠,农舍优势种为黄胸鼠,防治适期为4—5月和8—9月两个害鼠活动高峰期;化学药物防治是综合防治的主要措施;准确掌握鼠情动态,选择高效、安全杀鼠剂,采用正确的投饵技术,才能取得理想的灭鼠效果。  相似文献   

19.
The equivalent transmission line method is extended to multi-transverse electric modes of cavity which are introduced by aperture coupling, and it is used to analyze the shielding effectiveness of rectangular enclosures with apertures. The multimode transmission line method is verified by HFSS(High Frequency Structure Simulator). The results show that higher-order mode is essential to obtain an accurate shielding effectiveness of rectangular enclosure on wide frequency domain. Below the frequency of 1 GHz, nearer to the slot, the impact of higher-order mode on the shielding effectiveness is greater in the place mear the slot. Higher-order mode leads to a better shielding effectiveness.  相似文献   

20.
Yield stability is an important trait of crop cultivars. There are different concepts and measures of stability, and new ones are constantly being proposed, leaving the practitioner with an ever growing collection of measures to chose from.
In order to facilitate the choice it is useful to study the relationship between stability measures. This paper compares the well known ecovalence to a new measure, the variance of relative yields. It is argued that under rather restrictive conditions the new measure is essentially equivalent to the ecovalence, while in most cases it displays an undesirable dependence on genotypic mean yield. It is concluded that the ecovalence is generally preferable.  相似文献   

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