城市内部绿道布局特征及量化控制指标体系建构

针对我国绿道规划研究和实践的薄弱点,着重研究探讨了在城市内部即城市建设用地范畴下的绿道布局特征及布局控制方法。论文首先对于绿道在国外的发展和我国的实践情况进行概述,阐明了研究城市内部绿道规划的必要性;然后结合游憩需求圈层、居住区和公园绿地的等级特征划分了绿道的等级,并在此基础上梳理了绿道的空间布局特征;最后,围绕绿道布局量化控制,讨论了城市内部绿道布局量化控制指标体系建构和量化控制指标值的推导途径。

机床基础件动态特性影响因素的研究及应用

对某加工中心的床身、立柱基础件进行建模,采用弹簧-阻尼单元法对连接的结合面进行处理,完成基础件的动态特性分析。根据得到的前6阶模态的振型及频率数值,找出结构设计中的薄弱环节,并提出改进意见。改变筋板单元孔孔径大小、布局密度、单元孔形状,分析不同筋板结构型式的床身、立柱的性能,获得影响基础件动态特性的参数变化规律,得出选择合适孔径数据、增加筋板布局密度,能有效提高基础件动态性能。所得结论具有工程应用推广价值,同时为机床基础件结构改进、设计优化提供理论依据。

Composite grid method for analysis of electromagnetic field

In this paper, a composite grid method (CGM) for finite element (FE) analysisof an electromagnetic field with strong local interest is proposed. The method is based on theregular finite element method in conjunction with three basic steps, i.e. global analysis, localanalysis, and modified global analysis. In the first two steps, a coarse finite element mesh is usedto analyze the global model to obtain the nodal potentials which are subsequently used asartificial boundary conditions for local regions of interest. These local regions with theprescribed boundary conditions are then analyzed with refined meshes to obtain more accuratepotential and density distribution In the third step, a modified global analysis is performed toobtain more improved solution for potential and density distribution. And iteratively, successivelyimproved solutions can be obtained until the desired accuracy is achieved. Various numericalexperiments show that CCM yields accurate solutions with significant savings in computing timecompared with the regular finite element method.

Optimum Density of Standings and Schemes of Tomato Plants Placement in Uzbekistan

This article reports the results of researches by definition of optimum schemes of accommodation and density standings of tomatoes in 2009-2011 in conditions of Tashkent area of Republic Uzbekistan. Experiences were spent with domestic sorts Uzbekistan and Shark Yulduzi. The following schemes of accommodation and plants of density standing were tested： 70×30 cm and 90×23 cm at density of standing of 47,619 plants/hectares; 70×35 cm and 90×27 cm, 40,816 plants/hectares; 70×40 cm and 90×31 cm, 35,774 plants/hectares. The area of one plant feeding was 0.21, 0.245 and 0.28 ms. Schemes of accommodation and the area of plant feeding within the limits of the tested parameters do not render essential effect upon speed of plant development. Some acceleration （for 1-2 days） introductions into flowering are noted only at increase in the area of plant feeding with 0.21 ms up to 0.28 m^2. It was established that granting to plants of the greater feeding area as due to increase in distance between plants in the lines, and increases in row width strengthens growth of an elevated vegetative part of plants, especially due to increase amount of lateral branches. The greatest general and commodity harvest and the largest fruits sort ＂Uzbekistan＂ forms at density of standing in 40,816 plants/hectares, at schemes 90×27 cm and 70×35 cm, and more compact sort ＂Shark Yulduzi＂ at density of standing of 47,619 plants/hectares and the scheme 90×23 cm.

Global characteristics of the second-order ionospheric delay error using inversion of electron density profiles from COSMIC occultation data

It is a well known fact that ionospheric delay error is a predominant factor which influences the positioning accuarcy of GNSS.Although the main part of the first-order ionospheric delay error can be removed by the frequency-dependent behaviors of the ionosphere,the second-order ionospheric delay error must be eliminated to achieve millimetre-scale positioning accuracy.Due to COSMIC occultation providing electron density profiles on the global scale,the paper presents the first-order and the second-order ionospheric delay error analysis on the global scale using the inversion of electron density profiles from COSMIC occultation data during 2009–2011.Firstly,because of the special geographical location of three ISR(incoherent scatter radar),the first-order and the second-order ionospheric delay errors are calculated and discussed;the paper also shows and analyzes the diurnal,seasonal,semi-annual variation of ionospheric delay error with respect to signal direction.Results show that for the L1 signal path,the first-order ionospheric delay error is the largest near the equator,which is circa 7 m;the maximum second-order ionospheric delay error are circa 0.6 cm,0.8 cm and 0.6 cm respectively for L1 signals coming from the zenith,the north and the south at 10 degree elevation angles.The second-order ionospheric delay error on the L1 signal path from zenith are the symmetry between 15°and 15°with respect to magnetic equator,and are nearly zero at the magnetic equator.For the first time,the second-order ionospheric delay error on the global scale is presented,so this research will greatly contribute to analysing the higher-order ionospheric delay error characteristics on the global scale.