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1.
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   

2.
In this paper, a calculation method of forming cutter contour of involute helical with arbitrary easement is presented, the segmantal arcs of the best uniform approximation and tolerance to fit smoothly the cutter contour points are used the profile on the cross section of the helical is calculated and the design of the cutter is examined. The method can be used to design precision forming cutter of involute helical with the arbitrary easement. It is valuable in engineering application.  相似文献   

3.
《保鲜与加工》2003,(10):120-123
Some ideas of uniform design in the test design are introduced into Simulated Annealing Arithmetic and a new method of design based on uniform design is discussed. The global optimal solutions of nonlinear multi-peak function can be found by this method. A series of uniformly distributed points are generated by the principle of the uniform design in variable design space. These points are regarded as a series of start points of the optimization model. The Simulated Annealing Arithmetic is chosen to compute and a series of local minimum values can be gained. Before compared with each other, the best value of all local minimum values can be found out, the value is thought as the global minimum in some degree. According to the method, a program is compiled and an example of design is implemented. The result of the example testifies that the method is feasible.  相似文献   

4.
To obtain the most important influence factors in road route selection quickly and effectively, we put forward a method that we call an analytic hierarchy process. In this method, we first use a matrix to show the mutual relationships of factors. We then analyze and calculate the matrix. Finally, we obtain the relative importance of all factors in the overall system. The result derived using this method is more reasonable and more direct viewing to reflect influence coefficient. And based on the firsthand information of designs and the social background, the method can give qualitative indicators before program design, which prevented blindness of designing process and the designer can get more suitable road lines.  相似文献   

5.
Recombinant inbred lines (RILs) are created by a cross between inbred lines followed by repeated selfing or sib-mating, which include many different types of new inbred lines with many recombination events on the genome. The phenotype of each RIL can be assessed based on multiple individuals within the same line to reduce non-genetic variability. Therefore, RILs are useful tools for QTL mapping allowing effective detection and fine localization of QTL. Usually only two inbred lines are involved to create RILs. In such two-way RILs, however, there are at most two different alleles at QTL and only QTL segregating between two parental lines can be detected. Recently a new crossing design using multiple founders for creating RILs was proposed in Arabidopsis thaliana and mice, where the genome of each RIL is a mosaic of the genomes from multiple parents. Such multi-way RILs are more useful to improve the efficiency in QTL detection than two-way RILs because of the increased chance of QTL segregation among multiple lines, leading to the successful detection of many QTL. In this paper, we propose a Bayesian method for mapping multiple QTL simultaneously in four-way RILs allowing the inference about the equivalence relationship among the four possible alleles descended from the four founder lines as well as the estimation of QTL locations and effects via a MCMC algorithm. Simulation experiments show that our method has the practical ability to detect QTL and to provide the information of equivalence relationship among alleles at detected QTL using four-way RILs.  相似文献   

6.
Higher-order elliptical bevel gear is a typical form of the noncircular bevel gear transmission.Space spherical coordinate system of the bevel gear meshing is set up based on the meshing theory of space transmission.The varying relationship among the pitch curve,tooth profile and mesh lines are analyzed,and the equation of the gear tooth surface is developed with matrix method based on space coordinate transformation.The basic parameters of the noncircular bevel gear such as transmission ratio,modulus and the number of teeth are designed,and detailed analysis of the influence of the eccentricity on the relevant parameters is carried out as well.By using discrete numerical method and three-dimensional software,the mathematical model of the tooth profile and virtual physical model of the noncircular bevel gear are established,and then simulation on its motion and interference checking are performed.Finally,the approach for design,calculation and generation of the tooth profile is obtained and its correction has been verified by experiment.  相似文献   

7.
四向杂交设计QTL分析的极大似然方法   总被引:2,自引:0,他引:2  
敖雁  徐辰武 《作物学报》2006,32(1):51-56
四向杂交(four-way cross)设计是指4个纯系亲本参与杂交衍生分离群体的一种交配设计。尽管国际上已经提出基于四向杂交设计的迭代重新加权最小平方(iteratively reweighed least squares,IRWLS)QTL作图方法,但该方法忽略了双侧标记基因型内QTL基因型的混合分布特性,当QTL位置和标记的位置不重合时作图精度较低。本文根据四向杂交设计的数量遗传模型,发展出基于四向杂交设计和混合分布理论的QTL作图的极大似然估计方法。首先利用染色体上所有标记基因型联合计算该染色体上任一假定位置QTL的条件概率,然后根据混合分布理论建立基于EM算法实现的QTL作图的极大似然估计方法。以计算机模拟数据研究了QTL遗传力、样本容量和分子标记信息含量3个因素对方法的影响,结果表明,(1)在QTL的被发现能力上,标记信息不完全的四向杂交设计仅略低于信息完全时的四向杂交设计;(2)随着QTL遗传力、样本容量和标记信息含量的增大,QTL位置以及效应估计值的准确度和精确度逐步提高。  相似文献   

8.
现有IEEE(institute of electrical and electronics engineers)标准,目前只能明确0.5~1.7 MHz有限频段的输电线路无源干扰谐振机理。为拓展输电线路无源干扰谐振的研究频率,引入广义谐振理论,提出了一种基于电磁场能量平衡的干扰谐振频率预测构想。将大尺度空间下输电线路铁塔阵列及天线等效为广义封闭系统,从而基于复坡印廷定理,推导了电磁开放系统广义谐振因子的表达式,求解得到的广义谐振因子零值点为无源干扰谐振频点。该方法由于避开了传统将铁塔等效为半波天线的局限,因此可以实现中波频段无源干扰谐振预测。采用IEEE标准算例进行验证,结果表明:1.7 MHz频率以下,基于广义谐振理论的无源干扰谐振频率预测值和缩比模型实测值最大误差不超过±0.169 MHz。  相似文献   

9.
Basing on the theory of engagement, a design has been done for a new type of counter-intermeshing twin-screw kneader. Profile of the screw includes arcs and its envelope lines, and the profile is smooth and continuous without cuspidal points. Milling cutter blade profiles also have been calculated and corrected for manufacturing the helical parts designed and getting the clearance acquired. There may be interference between the cutter and the workpiece, so interference check must be done to insure the milling cutter and screw will not be interfered.  相似文献   

10.
The doubled haploid breeding method can produce maize inbred lines faster than traditional methods, but there are challenges associated with it. Sorting haploid from hybrid seed based on visual colour markers is time consuming and can be difficult due to colour inhibitors that obscure pigmentation needed to distinguish between haploid, hybrid and outcrossed seed. In this study, weight was evaluated as a method to sort haploid from hybrid seed. A first experiment utilized two families for analysis in a preliminary study. Eleven haploid and hybrid kernels from both families were weighed for a total of 44 experimental units. A second experiment was carried out using six families, using the same format as the previous, for 132 experimental units. Hybrid seed weighed significantly more than haploid seed in both experiments. However, the interaction between line and kernel type was significant in the second experiment. In conclusion, efficacy of sorting haploid from hybrid kernels based on weight depends on the genotypes involved.  相似文献   

11.
According to existent problems on design and application of the cylindrical cam mechanism with the slide roller-follower, the one correct concept about profile design and pressure angle is presented. Based on this concept, the theoretical profile,practical profile,meshing surface equations and pressure angle formula of the cam mechanism are built up by using opp.rotation analysis and offset surface principle. This method is very simple and clear, and avoids the abstract analysing process in meshing principle. The mathematic models built by this paper can be used to design,manufacture and check this type of cam mechanism correctly, and also create conditions to make deeply meshing property analysis of this mechanism.  相似文献   

12.
Research on Lightning Intruded Wave for 500 kV Substations   总被引:1,自引:0,他引:1  
The study on overvoltage for 500 kV substation caused by lightning intruded wave is presented. In this paper, we calculate by using electromagnetic transient program (EMTP) and combine substation with incoming lines ,so some influence factors can be considered such as impulse voltage second characteristic of insulator strings, lightning stroke point on the incoming lines and impulse grounding resistance of towers. The results show that the method is close to the practice and some factors of incoming lines are important to overvoltage.  相似文献   

13.
An illuminance ratio model of both single and multiple sources was proposed. The model tried to compensate for a lighting dimming system acting incorrectly as a result of an illuminance sensor aimed at a workplace sheltered by paper or a human body. The method was based on a luminance transfer function matrix, and the model parameters were estimated via the least squares method. Simulated and experimental results show the illuminance calculated using the model is consistent with the actual situation. The illuminance sensor setting based on this model can not only reduce difficulties associated with laying lines, but also avoid incorrect action caused by the illuminance sensor aimed at a workplace sheltered by paper or a human body. This research serves as a reference for the design of lighting dimming systems.  相似文献   

14.
A product ontology screening method which can be used in variant design is proposed. With the support of complete ontology view of product resources, the product functional requirement and structural characteristics are converted to demand constraints, which are used to screen product ontology. For different screening hierarchies and objects, different screening rules such as pattern matching, case matching combined with manual decision and auto matching on the basis of case-based reasoning are adopted. The semi-automatic screening method with human-computer cooperation has impressive effectiveness on the improvements of the accuracy of design schemes and the flexibility and efficiency of design process. Finally, a variant design supporting system for building door and window is developed, which proves the feasibility and effectiveness of the method.  相似文献   

15.
Understanding the volatile profile of melon is an ever increasingly important task for breeders for enhancing their flavour component. For this purpose, F1 progeny and parental lines were analysed using headspace-solid phase microextraction gas chromatography–mass spectrometry-based analysis. Diallel analysis showed that most of the investigated compounds were controlled via non-additive genetic effects with general combining ability to specific combining ability ratios of less than 0.4. High heterosis results were observed in alcohols such as ethanol and octanol in both rind and mesocarp samples and benzylalcohol in the rind. It was also noted that the ester-based compounds with high heterosis values in mesocarp samples differed from those with heterosis in rind samples. These observations further emphasize the non-additive control of these compounds. It can be concluded that non-additive genetic control is strongly governing the genetic profile within the studied progeny. This finding indicated that dudaim lines as a valuable genetic material enhanced the volatile profile of odourless commercial types of ameri and inodorus melon.  相似文献   

16.
甜菜下胚轴颜色选择对后代品系及杂交组合的影响   总被引:1,自引:0,他引:1  
王华忠  张文彬 《作物学报》2007,33(6):1029-1033
为探讨甜菜幼苗下胚轴颜色与其他诸性状的相关关系,于1988—2003年对若干甜菜四倍体及二倍体多胚品系进行了4~6代幼苗下胚轴颜色的分离纯化选择、品系与原亲本比较、以红绿胚轴品系为亲本配制正反交组合等系列鉴定试验。结果表明,该选择方法对二倍体品系效果不明显,而四倍体后代品系与下胚轴颜色的联应F值达5%显著水平,红绿胚轴品系间的产、质量差异较大、互有高低,根产量相差20%以上,含糖率相差1%以上。绿胚轴品系含糖率大多数高于红胚轴品系,绿胚轴品系K、Na含量低于红胚轴品系,且大多达到1%或5%显著水准,而有害性氮含量则相反;红胚轴品系的株高、叶长、叶宽大于绿胚轴品系。利用四倍体和二倍体的红绿胚轴品系为亲本相互配制的杂交组合其产、质量存在显著差异。甜菜幼苗下胚轴颜色选择可以作为创新甜菜种质与品种选育的新方法,将下胚轴颜色作为品种的标记性状也很适用。  相似文献   

17.
J. S. C. Smith 《Euphytica》1988,39(3):199-205
Summary Determination of pedigree by laboratory means can provide an initial and rapid check of hybrid identity in studies designed to compare genotypes. In order to test the accuracy of such determinations, isozymic and chromatographic data were used in an attempt to ascribe pedigrees to 25 hybrids that were identified only by a letter code from a list of 30 inbred lines. The pedigrees of 9 single-cross hybrids were correctly deduced as was the direction in which each cross was made. The pedigrees of 2 hybrids could only be determined ambiguously, however these hybrids were reciprocals and the biochemical data were unable to distinguish between 2 related candidate inbred lines. Pedigrees of 3 hybrids were either incompletely determined or could not be determined from the list of 30 candidate inbred lines and were thus correctly identified as non-Pioneer® brand hybrids. Pedigrees of 9 3-way hybrids could be determined accurately but the pedigrees of 2 non-Pioneer® brand hybrids could not be deduced completely. The ability to correctly ascribe pedigrees of hybrids shows that these data provide a rapid means of determining whether additional field and laboratory tests would be warranted in tests designed to compare genotypic similarity of hybrids.  相似文献   

18.
The society-economy-environment appraisal for construction project can help our government to control macro-economy, make correlation policy and formulate laws and draw up city plan.It has great influence on the sustainable development of our society and it is the demand of the law for the environment evaluation in China.This paper introduced the basic structure of society-economy-environment appraisal system for construction project and the thought of elements transaction.Using the method of AHP, the model of project analyzing and optimizing selection is designed.For the more, the methods of the optimizing models on the selected schemes are put forward.Finally, the integrative analysis has been made on the system design and appliance of this appraisal system.  相似文献   

19.
In the deep sea, direct measurement of pipeline cathodic protection status is very difficult. We explored a non contact method by measuring the potential distribution of the environment field around the undersea pipelines to detect the rotted points on the coating surface. It included two aspects: developing a new type of the solid state Ag / AgCl reference electrode for the deep sea; useing the virtual instruments to design the environment field measurement system. The non contact measurement system was applied in the ocean of Qingdao city, P.R.China as experiments. The experimental results show that the non contact measurement system within four meter distance to the undersea pipelines, can accurately detect rotted points.  相似文献   

20.
为了探索适宜我国光照特点的大型温室补光设计方法,以最少的人工补光弥补自然光照的不足,本文对珠海市1997-2016年共20年的自然光照数据进行分析,结合番茄光照需求规律,提出珠海大型温室番茄长季节栽培补光设计方法.结果表明,珠海地区夏季和秋季的自然光照条件好,春季次之,冬季最差.结合番茄长季节栽培工艺及不同生长阶段光照...  相似文献   

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