AN APPLICATION OF TOPOLOGICAL ANALYSIS TO STUDYING THE THREE-DIMENSIONAL FLOW IN CASCADES;PART I—TOPOLOGICAL RULES FOR SKIN-FRICTION LINES AND SECTION STREAMLINES

Based on the working of Lighthill and Hunt et al., in the present paper the author has established the topological rules adapting to analysing the skin-friction lines and the section streamlines in cascades. These rules are (1) for a rotor cascade without shroud band, the total number of nodal points equals that the saddle points on the skin-friction line vector fields in eachpitch range; (2) for an annular or straight cascade with no-clearances at blade ends, the total number of saddle points is two more than that of nodal points on the skin-friction line fields in a pitch; (3) the total number of saddles in the secondary flow fields on cross-sections in cascade is one less than that of nodes; (4) in the section streamline vector fields on a meridian surface penetrating a flow passage, and on leading and trailing edge sections, the total number of nodes is equal to that of saddles; (5) on the streamline vector fields of a blade-to-blade surface, the total number of nodes is one less than that of saddles.

Structural Design and Optimization of Comb-type Electric Bicycle Three-dimensional Parking Garage

With the reduction of urban land, the three-dimensional garage is increasingly built with its advantages of saving land. But the current three-dimensional garage is built for the car. It is hardly stereo parking garage for electric bicycles. This paper designed a hollow tower electric bicycle stereo parking garage with fork comb structure, based on the analysis of the characteristics of electric bicycles and the characteristics of existing three-dimensional garages. A fixed comb is mounted on the garage frame. The movable comb is mounted on the middle lift mechanism of the garage. The access of the vehicle is achieved by the exchange of the comb. The key comb structure was modeled using SolidWorks software and the stress distribution of the structure was analyzed. It was optimized by MATLAB software. The result shows that this structure can improve access efficiency. The quality of the comb structure can be minimized under the constraints of strength requirements.

A fast and precise three-dimensional measurement system based on multiple parallel line lasers

This paper conducts a trade-off between efficiency and accuracy of three-dimensional(3 D)shape measurement based on the triangulation principle,and introduces a flying and precise 3 D shape measurement method based on multiple parallel line lasers.Firstly,we establish the measurement model of the multiple parallel line lasers system,and introduce the concept that multiple base planes can help to deduce the unified formula of the measurement system and are used in simplifying the process of the calibration.Then,the constraint of the line spatial frequency,which maximizes the measurement efficiency while ensuring accuracy,is determined according to the height distribution of the object.Secondly,the simulation analyzing the variation of the systemic resolution quantitatively under the circumstance of a set of specific parameters is performed,which provides a fundamental thesis for option of the four system parameters.Thirdly,for the application of the precision measurement in the industrial field,additional profiles are acquired to improve the lateral resolution by applying a motor to scan the 3 D surface.Finally,compared with the line laser,the experimental study shows that the present method of obtaining 41220 points per frame improves the measurement efficiency.Furthermore,the accuracy and the process of the calibration are advanced in comparison with the existing multiple-line laser and the structured light makes an accuracy better than 0.22 mm at a distance of 956.02 mm.

Development of an In-Situ Laser Machining System Using a Three-Dimensional Galvanometer Scanner

In this study, a three-dimensional (3D) in-situ laser machining system integrating laser measurement and machining was built using a 3D galvanometer scanner equipped with a side-axis industrial camera. A line structured light measurement model based on a galvanometer scanner was proposed to obtain the 3D information of the workpiece. A height calibration method was proposed to further ensure measurement accuracy, so as to achieve accurate laser focusing. In-situ machining software was developed to realize time-saving and labor-saving 3D laser processing. The feasibility and practicability of this in-situ laser machining system were verified using specific cases. In comparison with the conventional line structured light measurement method, the proposed methods do not require light plane calibration, and do not need additional motion axes for 3D reconstruction;thus they provide technical and cost advantages. The insitu laser machining system realizes a simple operation process by integrating measurement and machining,which greatly reduces labor and time costs.

Line ×Tester Analysis of Tropical High Land Maize (<i>Zea mays</i>L.) Inbred Lines Top Crossed with Three East African Maize Populations

Maize breeding efforts to generate high yielding and adaptive cultivars have recently been given emphasis by national maize breeding program. In Ethiopia, the maize production system is mainly dominated by subsistence farmers where their production is below average. The objectives of this study were to determine the combining ability between lines and testers, and to evaluate the performance of crosses (hybrids) and parents for grain yield and yield component traits. Twenty-seven inbred lines were generated by crossing nine female lines (L1-L9) and three male testers (T1-T3) using line × tester mating system at International Maize and Wheat Improvement Center (CIMMYT), East African high land maize improvement program. The inbred lines along with parents were evaluated in randomized complete block design with two replications at three locations (Ambo, Kulumsa and Haramaya). Significant differences were observed among genotypes for all ten traits considered. Eight crosses (L1 × T2, L1 × T3, L3 × T3, L8 × T1, L4 × T2, L9 × T1, L2 × T1, and L2 × T2) had higher yield performance compared to other crosses across environments. Significant mean square differences were found across locations for general combining ability (GCA) due to lines for all traits except for number of kernel rows per ear, whereas GCA due to testers were significant only for grain yield, ear length and 1000-seed weight. Significant mean square due to GCA × Loc (both for lines and testers) was found for days to maturity (38.71*), 1000-seed weight (4582.36**) and grain yield (2756777**), while significant SCA × Loc interaction was found for all traits except number of kernel rows per ear (1.07), ear length (0.79) and ear diameter (0.12), suggesting that the importance of additive and non-additive gene effects in controlling these characters.

Three-dimensional analysis of pedicle screw channel,screw entry point and lateral surface of cervical vertebral body

Objective To explore three-dimensional relations of pedicle screw channel (PSC) ,screw entry point and lateral surface of cervical vertebral body by digital techniques. Methods CT scan images of cervical

光频梳下变频信号光纤延时频率恢复方法

针对光频梳下变频信号接收过程中存在的频率信息丢失问题,提出了一种基于频率-相位映射的信号频率恢复方法,该方法使用可调光纤延迟线在两路光频梳变频链路之间产生一组固定已知的时延,时延在信号原始频率与下变频信号相位差之间建立映射关系,利用该映射关系可以从测得的相位差计算出信号的原始频率。分析了时延值等参数对频率恢复的影响,估计了该方法对相位测量不确定度的限值要求,最后给出了该方法具体实施方案中关键参数的设置策略。所有下变频信号的相位差可以通过快速傅里叶变换等数据处理一次性得出,因此该方法的时间代价和计算成本几乎不随着信号个数增加而增加。在不考虑下变频信号混叠的情况下,本文所提出的方法在理论上对处理信号的数量没有限制,因此相比于已有的光频梳下变频信号频率恢复方法,在多信号频率恢复方面更具有优势。

Evaluation of Two Momentum Control Variable Schemes and Their Impact on the Variational Assimilation of Radar Wind Data:Case Study of a Squall Line

Different choices of control variables in variational assimilation can bring about different influences on the analyzed atmospheric state. Based on the WRF model＇s three-dimensional variational assimilation system, this study compares the be- havior of two momentum control variable options-streamfunction velocity potential （ψ-χ） and horizontal wind components （U-V）-in radar wind data assimilation for a squall line case that occurred in Jiangsu Province on 24 August 2014. The wind increment from the single observation test shows that the ψ-χ control variable scheme produces negative increments in the neighborhood around the observation point because streamfunction and velocity potential preserve integrals of velocity. On the contrary, the U-V control variable scheme objectively reflects the information of the observation itself. Furthermore, radial velocity data from 17 Doppler radars in eastern China are assimilated. As compared to the impact of conventional observation, the assimilation of radar radial velocity based on the U-V control variable scheme significantly improves the mesoscale dynamic field in the initial condition. The enhanced low-level jet stream, water vapor convergence and low-level wind shear result in better squall line forecasting. However, the ψ-χ control variable scheme generates a discontinuous wind field and unrealistic convergence/divergence in the analyzed field, which lead to a degraded precipitation forecast.

Evaluation of earthquake impact on magnitude of the minimum principal stress along a shotcrete lined pressure tunnel in Nepal

In situ stress condition in rock mass is influenced by both tectonic activity and geological environment such as faulting and shearing in the rock mass.This influence is of significance in the Himalayan region,where the tectonic movement is active,resulting in periodic dynamic earthquakes.Each large-scale earthquake causes both accumulation and sudden release of strain energy,instigating changes in the in situ stress environment in the rock mass.This paper first highlights the importance of the magnitude of the minimum principal stress in the design of unlined or shotcrete lined pressure tunnel as water conveyance system used for hydropower schemes.Then we evaluated the influence of local shear faults on the magnitude of the minimum principal stress along the shotcrete lined high pressure tunnel of Upper Tamakoshi Hydroelectric Project(UTHP)in Nepal.A detailed assessment of the in situ stress state is carried out using both measured data and three-dimensional(3D)numerical analyses with FLAC3D.Finally,analysis is carried out on the possible changes in the magnitude of the minimum principal stress in the rock mass caused by seismic movement(dynamic loading).A permanent change in the stress state at and nearby the area of shear zones along the tunnel alignment is found to be an eminent process.

Scaling properties of phase-change line memory

Phase-change line memory cells with different line widths are fabricated using focused-ion-beam deposited C-Pt as a hard mask. The electrical performance of these memory devices was characterized. The current^oltage （I-V） and resistance-voltage （RV） characteristics demonstrate that the power consumption decreases with the width of the phase-change line. A three-dimensional simulation is carried out to further study the scaling properties of the phase- change line memory. The results show that the resistive amorphous （RESET） power consumption is proportional to the cross-sectional area of the phase-change line, but increases as the line length decreases.

太赫兹量子级联激光器光频梳射频传输

针对太赫兹量子级联激光器光频梳射频信号提取与传输存在的阻抗不匹配问题,设计并提出了一种输入阻抗为20Ω、输出阻抗为50Ω的渐变微带线结构,研究了该结构的准TEM模电场分布,并根据S参数建立了相应的LC等效电路模型分析其物理机理。实验中,将渐变微带线结构应用于太赫兹量子级联激光器光频梳射频信号提取与测试,以验证渐变微带线传输射频信号效果,成功测量得到太赫兹量子级联激光器重复频率,其线宽为3.7 kHz,信噪比达到60 dB,在注入电流为700~900 mA范围内重复频率表现为稳定的单模信号,测量得到的最大保持和幅度艾伦方差结果同样表现出重复频率的稳定性。实验结果表明,所设计的渐变微带线具有良好的阻抗匹配效果,能够实现对太赫兹量子级联激光器光频梳射频信号稳定的提取和传输。

Three-dimensional elasticity solution of simple-supported rectangular plate on point supports, line supports and elastic foundation

This paper studies the bending of simple-supported rectangular plate on point supports, line supports and elastic foundation. On the basis of three-dimensional elasticity theory, the exact expressions of the displacement functions, which satisfy the governing differential equations and the simply supported boundary conditions at four edges of the plate, are analytically derived. The reaction forces of the in- termediate supports are regarded as the unknown external forces acting on the lower surface of the plate. The unknown coefficients are then determined by the boundary conditions on the upper and lower surfaces of the plate. Comparing the numerical results obtained from the proposed method to those obtained from Kirchhoff plate theory, Mindlin plate theory and those obtained from the commer- cial finite element software ANSYS, the high accuracy of the present method has been demonstrated.

根据产量特殊配合力分析玉米自交系杂种优势群

采用NCII设计 ,以Mo17、B73、黄早四、丹 340、K12、K2 2为测验种 ,12个自交系为被测系 ,通过两年、两点完全区组试验设计 ,分析了 18个玉米自交系的配合力和杂种优势群。结果表明 ,18个自交系可分为 5群 ,即兰卡斯特 (Mo17和P138)、瑞得 (B73、8112、铁 792 2和掖 10 7)、四平头 (黄早四、K12和 5 15 )、旅大红骨 (丹 340、E2 8、自 330、S37和 8 93)和PA群 (K2 2、CA15 6、掖 4 78和沈 5 0 0 3)。在 72个杂交组合中 ,K12× 8 93、B73×S37、B73× 8 93、K2 2×S37、Mo17× 8 93、Mo17×S37、丹 340×铁 792 2、丹 340×P138、丹 340×S37为 9个强优势组合。K12、S37、8 93和丹340的产量一般配合力高 ,参与组配的强优势组合较多。因此 ,这 4个自交系及其衍生系在我国玉米育种和生产中会有较大的应用潜力。

棉花Bt转基因品系的配合力和杂种优势表现(英文)

五个转基因品系和受体冀棉321配制成双列杂交,通过对产量性状和纤维品质的两年试验分析,结果发现:与受体品种相比,转基因品系的农艺性状有显著变化,说明转基因过程也会使部分农艺性状得到改善。转基因品系间的一般配合力有显著差异,其中有两个品系表现显著的正向一般配合力。杂交种F1的表现也呈现显著差异;两个不同转基因品系间的杂种优势,低于转基因品系与受体品种间的杂种优势。这些变异可能是Bt插入引起的,不同插入位点的相互作用可能会降低杂种优势。

高油玉米自交系的杂种优势群划分和优势模式分析

以分属Lancaster、Reid、塘四平头、旅大红骨和外引种质群等5个不同杂种优势群的代表性自交系Mo17、792 2、K12、丹340和870 1为测验种,以来自于BHO、ALEXHO、RYDHO、SYNDO等4个不同高油群体的2 0个自交系为被测系,利用NCⅡ设计分析了被测系的配合力、杂种优势群、杂种优势模式及其在生产实际中的利用价值。结果表明,2 0个高油自交系可分为2个杂种优势群,第一群主要为RYDHO(Reid高油)和SYNDO (SyntheticDiseasedOil)群体选系;第二群主要为ALEXHO(Alexanderhighoil)和BHO(北农大高油)群体选系。根据高油玉米种质的杂种优势类群和杂种优势利用模式划分结果,综合分析得出高油玉米种质与普通玉米种质杂种优势利用的9种模式,即ALEXHO×外引种质,ALEXHO×Reid ,ALEXHO×旅大红骨,BHO×外引种质,BHO×Reid ,RYDHO×Lancaster,RYDHO×塘四平头,SYNDO×外引种质,SYNDO×旅大红骨。其中ALEXHO×外引种质、ALEXHO×Reid、ALEXHO×旅大红骨、BHO×外引种质、BHO×Reid为5种主要模式。ALEXHO和BHO为选育优良高油玉米自交系的主要群体。

新疆中熟玉米自交系配合力分析和杂种优势群研究

为了研究新疆中熟玉米自交系的配合力和杂种优势模式,以13份新选育中熟玉米自交系为试材,采用NCⅡ的遗传设计,以B73、MO17、黄早四、齐319、丹340为标准测验种,13个新选育的玉米自交系为被测系,测定并分析18份玉米自交系材料的配合力和杂种优势群。结果表明,18个自交系可分为5群,即兰卡斯特(MO17、TS31)、瑞德(B73、L4-6、X1)、四平头(黄早四、8504、108F和B2)、PB群(齐319、W313、L4-10)、旅大红骨(丹340、Q3012、L4-89、L4-20、X3、B1)。其中,TS31、108F、L4-89、L4-10的一般配合力较高,可以作为优良的亲本直接用于杂交种的选育。65个杂交组合中L4-10×丹340、L4-89×B73、108F×B73、W313×丹340等13个的杂种优势比较强。可见,新疆地区SS群与NSS群配置的组合杂种优势一般较强,所有的强优势组合的两亲本一般都具有较高的一般配合力,而且产量构成因子具有互补性。

不同轮回选择改良轮次玉米群体选系的育种潜势

【目的】研究18个从不同轮回选择改良轮次玉米群体中选育自交系的育种潜势,为玉米群体的有效改良及育种利用提供理论依据。【方法】以2个群体3个不同轮次改良后代中选育的高代自交系为材料,通过农艺性状表型鉴定、配合力测定和SSR分子标记遗传多态性分析的方法,对这些群体高代选系的育种潜势进行研究。【结果】改良群体高代选系产量和主要构成性状及其GCA表现优于基础群体高代选系,但多数改良群体高代选系株高、穗位高及其GCA都较各自的基础群体高代选系有所增加。不同群体高代选系之间,表型及配合力差异较大,来自同一群体不同基本株的选系之间差异也较大。SSR分析结果表明,改良群体高代选系在自交代数少1代的情况下,其纯合的位点比例与基础群体高代选系相当,与基础群体高代选系相比,改良群体高代选系间遗传差异虽有减小的趋势,但仍有较大的遗传差异。改良群体高代选系P4MSC2-1、P4MSC2-2、P5MSC2-2和P5MSC2-3以及基础群体高代选系P5C0-3,自身产量和主要性状及其GCA表现较好,与测验种所配组合产量较高,有较大的育种利用价值。【结论】群体高代选系的表型和配合力差异来源于不同群体及基本株的差异,从经过改良的群体中选育出的自交系表现更好,用改良群体选系纯合速度较快。

四川部分玉米骨干自交系杂种优势群研究

以四川15个玉米骨干自交系及其按Giffing方法4组配的105个杂交组合为供试材料,通过配合力分析和单株产量特殊配合力、RAPD标记、SSR标记的聚类分析,研究供试自交系的配合力表现,杂优类群和杂优模式,并对不同研究方法划分杂优类群的可靠性进行比较。结果表明,单株平均产量及其构成性状GCA综合表现较好的自交系有18-599、7327、698-3、S37、48-2,单株产量SCA较高的组合中,自交系18-599和7327组配的杂交组合较多,其余自交系各自有其突出的优良特点,可根据育种要求加以利用;SSR分析可将供试的15个玉米骨干自交系较为合理地划分为4个类群和4个亚群,并发现杂优类群及其组配方式与单株产量的高低存在紧密的联系;三种聚类方法的分析结果,均能在一定程度上反映供试自交系的遗传特性,并且所划杂优类群具有程度不同的合理性,但无论从系谱关系还是从强优势组合方式来看,SSR分析结果更为准确和可靠。

67 GHz宽带谐波相位参考及其定标技术

作为非线性矢量网络分析仪的重要参考测量通道,谐波相位参考能够提供多频点、多波量以及复频率下的绝对相位测量能力。设计了基于共面波导非线性传输线方案的原型谐波相位参考样机,并提出了基于EOS光电采样系统的完整谐波相位参考定标技术,主要包括时基失配、平均去噪、相位对准、连接器失配与示波器复频率响应修正等流程。定标实验结果表明,原型样机能够在1 GHz功率27 d Bm信号激励下输出半峰值脉宽为22 ps的周期脉冲序列,其频带覆盖范围超过67 GHz,并在超高次谐波频点上拥有小于±10°的相位精度与小于±5°的相位可重复性。最后将原型样机装配到非线性矢网中,通过测量2 GHz信号激励下超窄时域脉冲发生器的输出时域信号,并将之与采样示波器测量结果进行比对,结果证实了谐波相位参考设计与定标技术的有效性与正确性。

一种滤除高采样心电工频干扰的改进算法

为了解决高采样频率下50 Hz工频及其倍频对心电波形的影响并保留有用的心电高频信息,提出一种滤除高采样心电工频干扰的改进算法。首先,通过修改零极点得到改进的IIR梳状陷波器,对带工频干扰的ECG信号进行滤波处理;然后,将滤波后的ECG信号进行线性段判别,并对线性段进行平滑滤波处理以消除振铃现象。通过R波幅值、信噪比(SNR)和均方误差(RMSE)对ECG信号工频干扰的消除结果进行评价,与其他4种滤波方法(平滑滤波、Notch滤波、自适应滤波和Levkov滤波)相比,IIR梳状陷波器改进方法得到的ECG信号R波幅值与原始未加工频的ECG信号最为接近,恢复率达到98%以上,且SNR提高约11倍、RMSE降低约30倍。所提出方法不仅能滤除高采样下的工频及其倍频的干扰,且能最大程度保留有用信号。