经常项目顺差与资本项目逆差——总体平衡目标下我国国际收支格局的较好选择

在经济全球化的今天,积极开展国际贸易已经成为国家发展的必经之路。那么,一个国家的出口贸易和进口贸易究竟孰多孰少,则在国际收支记账簿上体现为,一国是经常项目顺差还是资本项目逆差。本文将以中国步入21世纪以来的国际收支数据为支撑,分析我国的国际收支状况,以及确定我国国际收支平衡的总体目标,即应该是在总体平衡目标下的经常项目顺差与资本项目逆差。

测边网坐标的总体最小二乘平差方法

测边网坐标平差中由于已知点含有误差,因而其误差方程的系数矩阵含有误差且与边长观测值相关并精度不等。推导了该条件下的总体最小二乘平差公式,并利用矩阵拉直运算进行随机模型的求解,给出了总体最小二乘平差的精度评定公式。最后通过算例验证了该方法的有效性和可行性。

附有等式约束的加权总体最小二乘平差方法

等式约束可以充分利用已有的先验信息和观测信息,使参数在满足平差主模型的同时吻合所建立的等式约束先验信息。针对目前附有等式约束的总体最小二乘平差方法都是观测值与系数矩阵独立、等精度的情况,推导了附有随机等式约束和固定等式约束的加权总体最小二乘平差方法的计算公式和精度评定公式,对于附有等式约束的总体最小二乘方法在实际测量数据处理中的应用具有一定的借鉴作用。

总体最小二乘平差问题求解方法的比较

本文研究了总体最小二乘平差的两类方法,包括奇异值分解法和迭代解法,并且对两类方法进行比较。运用MATLAB软件对直线的多种情况进行了数据模拟,比较分析了总体最小二乘平差的不同方法以及最小二乘方法的结果,发现奇异值分解法与迭代解法的结果是一致的;迭代解法是从测量平差角度推导得到的,更适用于测量数据处理。

总体最小二乘平差理论解算方法对比分析

本文主要对现有的总体最小二乘平差理论进行了相关分析,结合其两种解算方式包括奇异值分解法和迭代解法,进行了相关的理论阐述,最终得到了总体最小二乘平差迭代解法更适合应用与测量平差分析。

罗德里格矩阵总体最小二乘法的应用研究

针对最小二乘法用于相似模型试验坐标转换时不能综合考虑系数矩阵误差的问题,提出采用总体最小二乘法用于相似模型试验的坐标转换,该方法以罗德里格矩阵为基础,同时顾及坐标转换方程中系数矩阵和观测向量中的误差,通过一定准则删除数据中的粗差或异常点,从而获得高精度的参数估计值。用近景摄影测量方法获取相似材料模型试验数据对该方法进行试验,结果验证了该方法的有效性和实用性。

服装CAD／CAM的特点及其总体评估

根据现有不同的服装ＣＡＤ／ＣＡＭ系统的特点进行了描述和分类，并对它们的应用情况的总体评估和专家跟踪调查提出了自己的看法，为服装ＣＡＤ／ＣＡＭ系统在我国的推广应用起到了抛砖引玉的作用。；□＊；四、服装ＣＡＤ／ＣＡＭ系统人机对话操作界面的方便性汉化程度：文件管理：衣片资料管理：工具栏按钮：□好；□好；□好；□好；□中；□中；□中；□中；□劣；□劣；□劣；□劣；其他：该项目评定星级：□＊；□；□＊；五、服装ＣＡＤ／ＣＡＭ系统运行尺寸精度图形显示精度：图形输入精度：图形输出精度：执行工作精度：□好；□好；□好；□好；□中；□中；□中；□中；□劣；□劣；□劣；□劣；其他：该项目评定星级：□＊；□；□＊；六、服装ＣＡＤ／ＣＡＭ系统的价格性能比价格／适用范围：价格／方便程度：价格／精度：价格／服务状况：□便宜；□便宜；□便宜；□便宜；□适中；□适中；□适中；□适中；□昂贵；□昂贵；□昂贵；□昂贵；其他：该项目评定星级：□＊；□；□＊；七、服装ＣＡＤ／ＣＡＭ系统的用户适应性大型企业：中型企业：小型企业：个体企业：□好；□好；□好；□好；□中；□中；□中；□中；□劣；□劣；□劣；□劣；其他：八、服装ＣＡＤ／ＣＡＭ系统对操作者?

罗德里格矩阵坐标转换模型的结构总体最小二乘估计

首先介绍了基于罗德里格矩阵坐标转换的基本原理,然后推导了基于罗德里格矩阵坐标转换的结构总体最小二乘的计算过程和公式,这样可以综合罗德里格矩阵坐标转换和结构总体最小二乘的优点,得到计算简单、精度更高的计算方法。最后通过算例说明该方法的有效性和可靠性。

The influence of different types of satisfaction on loyalty on C2C online shopping platform:From the perspective of sellers and the platform

With the rise and development of major types of platforms,the competition for resources has become extremely fierce,and the market share of C2C platforms has been seriously threatened by the loss of resources.Therefore,building and maintaining buyers’satisfaction and loyalty to C2C platforms is critical to the survival and sustainability of C2C platforms in China.However,the current knowledge on how platform satisfaction and loyalty are constructed in the C2C e-commerce environment is incomplete.In this study,seller-based satisfaction and platform-based satisfaction are constructed separately.We further distinguish seller-based transaction satisfaction into economic and social satisfaction and explore their antecedents and consequences.To test our research hypotheses,we conduct a survey and collect data from a real online market(Taobao website).The results show that seller-based transaction satisfaction positively affects platform-based overall satisfaction and loyalty,and that perceived product quality,perceived assurance,and perceived price fairness all have a significant effect on economic satisfaction,whereas perceived relationship quality and perceived empathy significantly influence social satisfaction.These findings help us understand the literature related to customer satisfaction in the context of C2C in China and provide inspiration for online sellers and platforms.

基于奇异值分解法的抗差总体最小二乘

在最小二乘平差中,认为只有观测向量中存在误差,因此当有粗差存在时,也只需要考虑观测向量中的粗差,采用抗差最小二乘可达到剔除粗差的目的。而总体最小二乘同时顾及了系数矩阵和观测向量中的误差,这就要求抗差总体最小二乘同时考虑系数矩阵和观测向量中的粗差。为了同时对粗差进行探测和定位,在加权总体最小二乘奇异值分解法的基础上,提出了一种总体最小二乘抗差估计,最后通过2个算例证明了本文提出方法的有效性和可行性。

摄影测量变形观测数据处理一体化软件系统的研制

根据摄影测量变形观测数据处理的理论和方法，研制出一个数据处理的一体化软件系统。本软件系统从坐标概值计算、粗差处理、总体平差、变形分析到图形显示，具有模块化、结构化、系统化特点。系统能处理多周期变形观测数据，系统既可整体运行，各模块也可独立工作。

一类新函数模型及通用加权总体最小二乘平差方法

针对摄影测量、计算机视觉、三维激光扫描、遥感影像几何纠正等领域中观测数据的特性,将y≈Aξ的变量含误差模型(EIV)拓展为y≈A(x)ξ的函数模型,该模型首先给出了设计矩阵协方差阵的计算方法,其次推导了一种通用的加权总体最小二乘(WTLS)平差算法和近似精度评定方法,并通过直线拟合、自回归模型参数估计算例进行验证计算.结果表明:无论观测值独立还是观测值相关,该方法与已有方法的WTLS平差结果及其精度一致,从而验证了该方法的正确性,且其算法更简洁方便.对于完善WTLS平差理论和方法,拓展总体最小二乘方法在3S技术中的应用有理论与现实意义.

病态加权总体最小二乘平差的岭估计解法

采用岭估计法处理加权总体最小二乘平差的病态性问题,推导了相应的求解公式及均方误差评定精度的方法,定义了病态加权总体最小二乘平差中的模型参数分辨矩阵,并讨论了岭参数的含义及其作用,给出了确定病态加权总体最小二乘岭估计中岭参数的岭迹法、广义交叉核实法和L曲线法。算例计算了普通最小二乘、普通总体最小二乘的结果,并比较了三种确定岭参数的方法在处理病态加权最小二乘岭估计和病态加权总体最小二乘岭估计中的优缺点。

线性EIV模型的TLS估计及其典型应用

推导了将线性GM模型转换为变量含误差(EIV)模型并采用总体最小二乘(TLS)平差的方法,介绍了加权总体最小二乘、混合总体最小二乘和附限制条件的总体最小二乘问题及其解算方法。以经典大地测量控制网平差和数据拟合算例比较各种TLS估计的精度和计算效益。理论分析和算例表明:对于EIV模型,WTLS为最优估计,实际应用时需根据具体函数模型和随机假设选择合理的TLS平差方法。

Study on the general layout of semi-submersible offshore drilling platforms based on process flow

The general layout of 6th generation semi-submersible drilling platforms is the main factor impacting the efficiency of their drilling operations. This paper provides a compound/integrated algorithm based on process flow that is aimed at improving efficiency, while giving attention to stability and safety at the same time. The paper describes the process flow of dual drilling centers and a hierarchical division of rigs based on the different modes of transportation of various drilling support systems. The general layout-centripetal overall arrangement spatially was determined based on drilling efficiency. We derived our modules according to drilling functionality; the modules became our basic layout units. We applied different layout algorithm to mark out the upper and lower decks. That is, the upper deck was designed based on the lowest transportation cost while the lower deck＇s calculations were based on the best-fit scope. Storage configurations in columns and pontoons were also considered for the layout design. Finally the center of gravity was taken into consideration and the general layout was adjusted accordingly, to result in an optimal center of gravity. The methodology of the general layout can provide a reference for implementation of domestic designs of semi-submersible rigs.

线性EIV模型的t型估计

将数理统计中的t型估计作为一种抗差估计引入测量平差中,提出线性EIV模型的t型抗差估计及其EM算法。以平面拟合为例,当向观测向量和系数矩阵加入粗差时,选取合适的自由度v,t型估计具有较好的抗粗差能力,求出的参数均值与真值偏差较小。

Influence of Sulphur Fertilizer on Sulphur Cycling and Its Implications on Sulphur Fertilizer Requirement of Grazed Pasture in Warm Seasonal Rangeland of Nei Monggol Steppe of China

Sulphur (S) cycling and implications on S fertilizer requirement in sheep-grazed pastures receiving three levels of S fertilizer at rates of 0, 30 and 60 kg S/hm 2 in 1995 and 1996 were studied using a mass-balance approach which accounted both for S inputs to and outputs from the soil-plant-animal system. Results indicated that S fertilizer increased by 50% of herbage S uptake and 15% or more of S bio-cycling rate in grazing system. The total S recovery of 30 and 60 kg S/hm 2 treatments from 1995 to 1996 was 74.0% and 37.6% respectively. Mineralization of organic S may be an important source of S for pasture when other S sources are low, accounted for 70% of the total S inputs without S fertilizer. The grazing sheep has an important ecological function, the feature of S cycling in grazed pastures was that 90% of herbage S ingested by grazing sheep was returned to soils as excreta. The amount of S released by sheep excreta accounted about 30% of the total released S through S bio-recycling. Loss from soil S leaching beyond the major plant rooting zone was the main S output from grazing system. However, urinary and fecal S losses, including transfer and leaching losses, also affected S budgets of grazing system. It is therefore important to investigate the recycling rate of both urinary and fecal S under field conditions. Based on the mass-balance principle, at least 10 kg S/hm 2 per year may be necessary for sustainable development of grazing system.

基于总体最小二乘法的系统响应修正方法

为了提高实时洪水预报的预报精度,提出了基于总体最小二乘平差理论的系统响应方法。传统的系统响应方法基于最小二乘法,只能考虑观测值的误差,因而传统的系统响应方法不能考虑动态系统响应矩阵存在的误差。对传统方法进行了分析并引入了总体最小二乘平差理论,改进方法同时考虑了动态系统响应矩阵和观测值的误差。针对动态系统响应矩阵的病态情形,通过总体最小二乘的岭估计解法给出稳定解。通过改进方法对新安江模型中的土壤含水量进行修正,应用于七里街流域,并与传统的系统响应方法进行比较。结果表明,两种方法都能提高模拟精度,改进方法相比于传统方法精度明显提升;改进方法的修正效果要优于传统方法,更加稳定。

一种加权总体最小二乘问题的解法

加权总体最小二乘(WTLS)方法是一种可同时顾及观测向量与系数矩阵误差的方法,其理论更为严密.基于已有总体最小二乘方法,推导了一种WTLS平差方法,该方法可顾及观测向量与系数矩阵中随机元素间的相关性;给出了一种可顾及相关观测情况下WTLS平差的新的等价平差准则,该准则具有与最小二乘(LS)平差准则相似的结构,进而可按照求解自由极值的方式进行推导,并将WTLS与LS平差思路进行了统一.针对推导过程中观测向量与系数矩阵组成的增广矩阵的协因数阵存在不可逆情况,构建的等价平差准则可避免直接对其求逆.通过直线拟合与二维仿射变换算例分析,结果表明:提出的方法能取得与已有平差方法相同的结果.并验证了该方法的正确性与可行性.

加权总体最小二乘的地面解析摄影测量算法

在分析加权总体最小二乘解与经典最小二乘解的区别和联系的基础上,将加权总体最小二乘平差理论首次应用于地面摄影测量的解析相对定向算法中,并给出了基于相对定向模型的加权总体最小二乘的算法步骤。同时,将Procrustes理论引入到解析绝对定向模型中,推导了基于Procrustes理论的加权总体最小二乘解。具体算例证明了加权总体最小二乘平差理论应用于地面摄影测量处理中能够获得精确稳定的解析参数。