利用无人机遥感提取育种小区玉米倒伏信息

研究了无人机遥感技术在小区尺度上进行玉米倒伏信息提取的可行性。笔者使用小型无人机通过无地面控制点的倾斜摄影方式，获得研究区的数字表面模型(DSM)，结合图像的红、绿、蓝色彩特征，采用图像分类的方法提取玉米倒伏信息，并在小区尺度上与田间调查结果进行对比分析。结果表明，数字表面模型所代表的玉米冠层高度差异信息与图像色彩特征具有良好的互补性，二者结合能够极大地提高玉米倒伏信息的提取精度。与田间调查数据相比，倒伏株数的误差只有4.44%，受倒伏影响的小区数量误差为9.26%，且85%以上小区内的株数误差小于5棵。玉米冠层高度结合色彩特征信息可精准地提取玉米倒伏信息；倾斜摄影测量方式可有效降低地面控制点缺失带来的模型内畸变，提高工作效率。该方法为小区尺度的玉米倒伏调查提供了一种简单、快速、有效的手段。     

Grey Optimal Options of Design Plans for Deep Cutting Slope

The selection of the design plans for deep cutting slope of high-level highway in mountain area,in general speaking,only depends on the designer's experience and intuitive determination at the present time,which results in unreasonable,even error,decision or plan.It unavoidably causes enormous damage.This paper proposes to adopt correlation degree analysis method of grey system theory for choosing the optimal design plan.It will give a definite and real meaning about choosing design plan and avoiding or reducing errors in design work.     

A NEW METHOD FOR DESIGN OF PSS PARAMETERS

The eigenvalue sensitivity methods is very useful not only in analysis of electric power system stability but also in design of the controllers. In this paper a new optimal method is proposed to design the parameters of PSS. Using this method the PSS is designed for a single machine-infinite bus system, and the results of digital simulation show that this method is very effective and useful.     

ON THE PROBLEM OF SWITCHING CONDITIONS FOR A KIND OF MINIMUM-TIME CONTROL SYSTEMS

The paper provides a detailed study of switching conditions of minimum-time control systems based on application in engineering. By analysis in theory and experiment, the authors deduce a set of switching conditions with state and control variabes inequality constraints, the variations of system parameters and the time-delay of computer in real time control. As an example, a DC motor speed control system is considered. By digital simulation and physical experiments,these conditions proved to be correct. The method in this paper is also suitable for other control systems using compound control algorithm.     

A SINGULARITY PROPAGATION FOR SEMILINEAR WAVE EQUATIONS

This paper discusses the propagation of singularity forsemilinear wave equations.By use of the theory of para-differentialoperators and the method of microlocal analysis,some results for generalsemilinear wave equations are obtained.     

Testing sky luminance distribution by fish-eye lens digital cameras

Abstract:To solve the existence of poor synchronization and large error in the sky luminance test, using fish-eye lens digital camera test sky luminance. Through researching on fish-eye lens and the optical characteristics of digital cameras, get the method that extract the luminance and location information of the measured sky element from digital photos, and determine the exposure parameters and the record range of linear brightness. Analyzing and amending the stability of the camera and light transmission rate of fish-eye lens, get a more accurate test values of sky luminance distribution. This provide important techniques means for daylighting research and daylighting observation.     

基于数字照片解析的黄瓜叶片面积测定及效果分析

为快速测定黄瓜叶片面积,开发了基于数字照片解析技术的叶片面积测定法,通过与坐标纸法、复印比重法对比,分析数字照片解析法的准确性与稳定性。结果表明：数字照片解析法与坐标纸法测定的结果无显著差异（配对检验P(p＞|t|)=0.872＞0.05）,复印比重法测定的结果较坐标纸法显著偏高。数字照片解析法较坐标纸法更为便捷、准确,可作为一种新的叶面积测定法推广使用。     

Design and Realize the Short Message Service System

Along with the widely using of mobile telephone, the SMS (Short Message Service) has achieved more and more approbation of consumers. Besides the point-point application of SMS among mobile phones, a new application of SMS between information system and mobile phones is developed quickly now, and it is a new way to achieve information conveniently and duly for users. In this paper, we design a software based on SMS to solve some problems which exists in the communication among employees. We also give out the system's functions, key technology and application in the enterprises. This system has some important value in theory and application for building a digital enterprise.     

AN ACCURATE FAULT LOCATION METHOD FOR PARALLEL TRANSMISSION LINES

So far, the accuracy of the existing methods of fault location based on calculating the impedance at only one terminal of lines is certainly affected by the variation of the system impedance at the remote end. In accordance with parallel lines' special characteristics, this paper presents a method that can calculate the system impedance of the remote end when one of the two lines has fault, so that the effect of its variation can be eliminated completely. This method has been tested by the computer digital simulation, and the results are very satisfactory.     

SERIES-PARALLEL CORRECTION AND CAA FOR CANONICAL SYSTEM TYPE 2

This paper presents a simple and efficient engineering design method of series-parallel correction for canonical system type 2 and gives a practical design example.The following and anti-disturbance performances of the system by means of digital simulation are analyzed.The performance indexes in different design parameters are listed.This paper is available for reference in engineerng design.     

Performance analysis on improved PDA AI for moving target tracking

Aim at the problem that the EO imaging tracking system is inconsistent with the model of probabilistic data association with amplitude information (PDA AI), which supposes that the greater the amplitude value is, the greater the probability of being the tracked target will be, a modified PDA AI (MPDA AI) is presented . Based on the fact that the amplitude and the motion of the interested target are consistent in a short period, the MPDA AI models the amplitude information and the motion information of the target as well as their consistency with Markov stationary signal to analyze the association procedure of motion and amplitude. The lower bounds of Cramer Rao estimation error for PDA AI and MPDA AI are calculated and discussed in detail. The theoretical analysis and experimental results show that estimating the target motion with the MPDA AI will be more accurate and more reliable than estimating with the original PDA AI.     

OPTIMAL SELECTION ON THE INTERVALS FOR HANDLIND THE RHYSICAL EXPERIMENT DATA BY THE METHOD OF DIFFERENCE WITH DATUM BY DATUM

This paper discusses the mechanism and reason for decreasing the handling polynomial function data on difference with durum by datum.From the error theory,some exemples are analysed and the equivalent principle for the intervals on datum by datum is presented.The optimal number for intervals is analysed in detail and shown by some examples for the correct result.At last,by making comparison between some methods for handling the physical experimental data to show the advantages of them,the proper condition and range in use for every method is also presented.     

Research on the Design Method of Digital Urban Lighting

This paper has introduced a kind of design method for digital urban lighting, it is an application of the illuminating engineering in digital city and a kind of measurable, dynamic visualization design method of the effect of digital urban lighting. A kind of new artificial method of scene imitation has been proposed in this paper. After taking pictures by verified digital camera, the luminosity and color information are taken to imitate the effect of urban lighting design, to display the current and future effect of lighting for the scene and thus optimize the urban lighting design plan to meet the demand of energy - conservation and beautifying the urban night scene.     

Vibration characteristics of face-gear transmission system with parametric excitation

In order to study the influences of different factors on nonlinear dynamics of face-gear transmission system, a nonlinear dynamic model is presented. This model includes backlash, general transmission error, time-varying meshing stiffness, meshing damping, bearings and external load, etc. Based on numerical analysis theory of nonlinear dynamics, the equations are solved and the bifurcation characteristics with different parameters are obtained. And the calculation results show that increasing the backlash and time-varying meshing stiffness will augment the dynamic load of system, but increasing the mesh damping will reduce the dynamic load effectively.     

水平不固定的试验结果的统计分析Ⅰ.一个因素的水平不固定时的分析

农业试验中某些数量因素的水平，常常难以控制到完全一致，而表现非固定变异。在结果分析时，如果忽略这种变异，对试验结果作方差分析，不仅使参数估计的方差增大，而且无法正确测验估计值的显著性。如果应用回归方法，可将因素的效应和互作定义相应的回归系数，参数的估计和假设测验均可得到保证。计算机模拟结果表明，当一     

An improved method for and error evaluation of modal pushover analysis

Based on evaluation of the basic principle and error of the modal pushover analysis method, an improved method is suggested by selecting rational values of stiffness reduction parameters of beams and columns in a reinforced concrete frame corresponding to the global target displacement ductility ratio. A 10 story and a 16 story reinforced concrete plane frame are designed as examples to investigate the influence of higher modes. Nonlinear seismic responses of the two frames under excitations of seven earthquake waves of varying earthquake intensities are selected to be the reference points for a comparison study. The changing rules of the results of modal pushover analysis and modified modal pushover analysis with respect to various natural fundamental periods and different earthquake intensities are studied. Research results show that the error of modal pushover analysis and modified modal pushover analysis will not increase with a larger fundamental period, which implies that modal pushover analysis can cover the effect of higher modes reasonably. When the degree of nonlinearity of the structure is more severe, the modified modal pushover analysis we suggest could decrease the error of normal modal pushover analysis to a certain extent.     

Error measure of filter used in optical wavelet transform for image data compression

This paper analyzs the error measure of filter used in optical wavelet transform for image data compression, designs a measure system for filter's error and implements it by using matlab platform, meanwhile, it indicat and overcom the shortage of Photoshop in image statistical characteristic analysis. The batch operation and the precision of histogram information. Experiment results have proven its correctness.     

A Method to Improve the Decoding Iteration Convergence Performance of Turbo Codes

Turbo codes is an effective method for digital communication systems to get near channel capacity error correcting performance, its iteration convergence performance is the key factor for practicability. Based on the universal decoding method of Turbo codes, a step increment factor was introduced in the paper to improve the iteration convergence performance. The method to generate the step increment factor was also presented as well as its' computer simulations. Simulation results show the method proposed can improve the convergence performance efficiency for Turbo codes with short interleaver.     

A FAST ALGORITHM FOR DIGITAL SIMULATTON OF HVDC SYSTEMS

After considering the features of the differential equations which have described the dynamic behaviours of HVDC systems, a fast algori -thm is presented for these equations. Compared with the fourth Runge-Kutta Method,this method has less amount of calculation with the same precision, numerical stability and other properties. Therefore, the use of the method has greatly increased the speed of the digital simulation of HVDC systems.In this paper an example of calculation is given, and the results obtained hv using this example are compared with the results obtained by calculating with the fourth Runge-Kutta Method. The speed of simulation by using this method is about 1.8 timss as fast as that by using the fourth Runge-Kutta Method.     

数字乡村发展的实践与探索——基于北京的调研

研究旨在通过分析北京市数字乡村建设实践,发现存在问题,找出推进路径,为数字乡村发展提供可借鉴经验。利用文献分析、典型案例和专家咨询法,探讨数字乡村发展理论与实践。数字化是现代农业4.0阶段的关键特征,数字经济是农业农村高质量发展的新引擎、新动能。北京是数字乡村发展的先行者,为北京乡村振兴和农业现代化建设打下了坚实基础。数字化基础设施完善,农业生产数字化、经营网络化和乡村治理数字化水平不断提升,乡村信息服务模式不断创新。数字乡村发展面临基础设施建设薄弱、数据资源体系建设不完善、数字技术与产业融合不够、数字乡村人才缺乏等问题。农业生产、农村生活、农产品经营和农业农村信息服务亟需与物联网、大数据、互联网、区块链、人工智能、5G等信息技术进一步融合。应不断夯实数字乡村建设基础,加大数字乡村科技研发,深化数字乡村技术产品推广应用,完善数字化乡村治理体系,强化数字乡村人才支撑。