A Quadratic Constraint Total Least-squares Algorithm for Hyperbolic Location

A novel algorithm for source location by utilizing the time difference of arrival (TDOA) measurements of a signal received at spatially separated sensors is proposed. The algorithm is based on quadratic constraint total least-squares (QC-TLS) method and gives an explicit solution. The total least-squares method is a generalized data fitting method that is appropriate for cases when the system model contains error or is not known exactly, and quadratic constraint, which could be realized via Lagrange multipliers technique, could constrain the solution to the location equations to improve location accuracy. Comparisons of performance with ordinary least-squares are made, and Monte Carlo simulations are performed. Simulation results indicate that the proposed algorithm has high location accuracy and achieves accuracy close to the Cramer-Rao lower bound (CRLB) near the small TDOA measurement error region.

Practical constrained least-square algorithm for moving source location using TDOA and FDOA measurements

By utilizing the time difference of arrival （TDOA） and frequency difference of arrival （FDOA） measurements of signals received at a number of receivers, a constrained least-square （CLS） algorithm for estimating the position and velocity of a moving source is proposed. By utilizing the Lagrange multipliers technique, the known relation between the intermediate variables and the source location coordinates could be exploited to constrain the solution. And without requiring apriori knowledge of TDOA and FDOA measurement noises, the proposed algorithm can satisfy the demand of practical applications. Additionally, on basis of con- volute and polynomial rooting operations, the Lagrange multipliers can be obtained efficiently and robustly allowing real-time imple- mentation and global convergence. Simulation results show that the proposed estimator achieves remarkably better performance than the two-step weighted least square （WLS） approach especially for higher measurement noise level.

Nonlinear total least-squares variance component estimation for GM(1,1)model

The solution of the grey model(GM(1,1)model)generally involves equal-precision observations,and the(co)variance matrix is established from the prior information.However,the data are generally available with unequal-precision measurements in reality.To deal with the errors of all observations for GM(1,1)model with errors-in-variables(EIV)structure,we exploit the total least-squares(TLS)algorithm to estimate the parameters of GM(1,1)model in this paper.Ignoring that the effect of the improper prior stochastic model and the homologous observations may degrade the accuracy of parameter estimation,we further present a nonlinear total least-squares variance component estimation approach for GM(1,1)model,which resorts to the minimum norm quadratic unbiased estimation(MINQUE).The practical and simulative experiments indicate that the presented approach has significant merits in improving the predictive accuracy in comparison with control methods.

Mid-term Outcomes of Primary Constrained Condylar Knee Arthroplasty for Severe Knee Deformity

This study aimed to examine the clinical and radiographic outcomes of primary total knee arthroplasy（TKA） with use of Nex Gen#174; Legacy#174; Constrained Condylar Knee（CCK） prosthesis for severe knee deformity. Clinical data of 46 patients（48 knees in total, aged 61 years on average） with severe knee deformity who underwent TKA with Nex Gen#174; Legacy#174; CCK prosthesis between December 2007 and February 2012 were retrospectively analyzed. There were 34 knees with severe valgus with incompetent medial collateral ligament, 11 knees with severe flexion contracture with inability to achieve knee balancing in flexion and extension by posterior soft tissue release, 2 knees with Charcot arthritis with severe varus and bone loss, and 1 with traumatic osteoarthritis with severe varus and ligamentous instability. The mean duration of follow-up was 71 months（range 40–90 months）. The New Knee Society scoring（NKSS） system and the Hospital for Special Surgery（HSS） score were used to evaluate the functional and clinical outcomes. Visual Analogue Scale（VAS） was used for pain measurement and Knee Society criteria for evaluation of radiological images. The results showed that, in the total 48 knees, 1 case of loosening due to short-stem tibial component at 3 months post-operatively underwent revision. The 6-year prosthesis survival rate in this cohort was 97.9%. There was no component infection occurring within 6 years. Significant post-operative improvements were found in NKSS and HSS scores. Patient satisfaction was significantly increased. Pain score was decreased significantly. Total functional score was improved from 31.46±11.43 to 86.42±8.87, range of motion（ROM） from 42.42°±23.57° to 95.31°±23.45° and the flexion contracture from 5.31°±7.87° to 0.92°±1.80°. Preoperative radiographic study showed excessive valgus（≥7°） in 37 knees, and varus deformity in 3 knees. Post-operative femorotibial alignment was valgus 3.88°±1.76° in 48 knees. Antero/posterior（A/P） view of X-ray films showed 4 radiolucent lines（RLL） in 48 tibial components. It was concluded that TKA with CCK is effective for the treatment of the severe unstable knee that cannot be balanced by soft tissue.

A Chance–Constrained Data Envelopment Analysis Approach to Problem Provincial Productivity Growth in Vietnamese Agriculture from 1995 to 2007

This study employs a chance-constrained data envelopment analysis (CDEA) approach with two models (model A and model B) to decompose provincial productivity growth in Vietnamese agriculture from 1995 to 2007 into technological progress and efficiency change. The differences between the chance - constrained programming model A and model B are assumptions imposed on the covariance matrix. The decomposition allows us to identify the contributions of technical change and the improvement in technical efficiency to productivity growth in Vietnamese production. Sixty-one provinces in Vietnam are classified into Mekong - technology and other -technology categories. We conduct a Mann-Whitney test to verify whether the two samples, the Mekong technology province sample and the other technology sample, are drawn from the same productivity change populations. The result of the Mann-Whitney test indicates that the differences between the Mekong technology category and the other technology category from two models are more significant. Two important questions are whether some provinces in the samples could maintain their relative efficiency rank positions in comparison with the others over the study period and how to further examine the agreements between the two models. The Kruskal - Wallis test statistic shows that technical efficiency from both models for some provinces are higher than those of them in the study period. The Malmquist results show that production frontier has contracted by around 1.3 percent and 0.31 percent from chance-constrained model A and model B, respectively, a year on average over the sample period. To examine the agreements or disagreements in the total factor productivity indexes we compute the correlation between Malmquist indexes, which is positive and not very high. Thus there is a little discrepancy between the two Malmquist indexes, estimated from the chance - constrained models A and B.

Instability after total hip arthroplasty

Instability following total hip arthroplasty(THA) is an unfortunately frequent and serious problem that requires thorough evaluation and preoperative planning before surgical intervention. Prevention through optimal index surgery is of great importance, as the management of an unstable THA is challenging even for an experienced joints surgeon. However, even after well-planned surgery, a significant incidence of recurrent instability still exists. Non-operative management is often successful if the components are well-fixed and correctly positioned in the absence of neurocognitive disorders. If conservative management fails, surgical options include revision of malpositioned components; exchange of modular components such as the femoral head and acetabular liner; bipolar arthroplasty; tripolar arthroplasty; use of a larger femoral head; use of a constrained liner; soft tissue reinforcement and advancement of the greater trochanter.

基于改进破产理论的省级用水总量控制指标分解

以吉林省为例,借鉴马斯洛需求理论开展各地级市分层次用水需求识别,构建“省-市”两级用水总量控制指标初始分配指标体系,基于充分保障区域用水的刚性需求,引入刚性需水量对传统破产理论准则进行改进。选取人口-用水总量基尼系数、GDP-用水总量基尼系数、人均综合用水量、万元GDP用水量4个指标评价用水总量控制指标分解方案的社会经济稳定性。研究结果表明,改进破产理论方法在省级用水总量控制指标分解中具有较高适用性,分解结果符合各地级市未来发展用水趋势,且均能满足各地区发展的刚性用水需求,有效提升了地区用水公平性与稳定性。具体体现在:与2020年实际分解方案相比,吉林省人口与用水总量匹配程度稳定性、GDP与用水总量匹配程度稳定性分别提升了11.03%、9.97%;大部分地级市用水水平与用水效率较现状年均有明显提升。与采用传统破产理论分解方案相比,吉林省人口与用水总量匹配程度稳定性、GDP与用水总量匹配程度稳定性分别提高了33.77%、18.32%;各地级市用水水平与用水效率变化更为合理。本研究可为各级水行政主管部门开展精细化用水管理提供参考借鉴,同时对于健全最严格水资源管理制度体系具有一定的技术价值。

企业数字化转型助推全要素生产率提升的理论与路径——基于A股上市公司的实证检验

当前中国数字经济蓬勃发展,企业进行数字化转型成为适应时代发展要求的重要选择。本文基于2011—2020年中国A股上市公司面板数据,运用固定效应模型、中介机制检验及异质性检验等方法,探究企业数字化转型影响其全要素生产率的效果与路径。研究发现:企业数字化转型能够显著提高其全要素生产率,其中缓解融资约束以及提高内部控制质量发挥中介作用;对不同所有权的企业而言,进行数字化转型均有利于提升全要素生产率,但是在非国有企业中效果更强;相对于成长期和衰退期企业,成熟期企业中二者作用效果更强。因此,企业应加快数字技术在各环节的应用,激发数字化转型积极效应;提升数字化转型的积极性,实施有差异化的转型战略;政府应发挥在宏观调控中的作用,优化数字化转型外部环境。

Constrained total least squares algorithm for passive location based on bearing-only measurements

The constrained total least squares algorithm for the passive location is presented based on the bearing-only measurements in this paper. By this algorithm the non-linear measurement equations are firstly transformed into linear equations and the effect of the measurement noise on the linear equation coefficients is analyzed, therefore the problem of the passive location can be considered as the problem of constrained total least squares, then the problem is changed into the optimized question without restraint which can be solved by the Newton algorithm, and finally the analysis of the location accuracy is given. The simulation results prove that the new algorithm is effective and practicable.

Results of a Second-generation Constrained Condylar Prosthesis in Complex Primary and Revision Total Knee Arthroplasty： A Mean 5.5-Year Follow-up

Background： The application of second-generation constrained condylar knee （CCK） prostheses has not been widely studied. This retrospective study was carried out to evaluate the clinical and radiographic outcomes of a second-generation CCK prosthesis for complex primary or revision total knee arthroplasty （TKA）. Methods： In total, 51 consecutive TKAs （47 patients） were performed between June 2003 and June 2013 using second-generation modular CCK prostheses. The follow-up was conducted at 3~a day, 1% 6＇h, and 12~h months postoperatively and later annually. Anteroposterior （AP）, lateral, skyline, and long-standing AP radiographs of the affected knees were taken. The Hospital for Special Surgery （HSS） Knee Score, the Knee Society Knee Score （KSKS）, the Knee Society Function Score （KSFS）, and range of motion （ROM） were also recorded. Heteroscedastic two-tailed Student＇s t-tests were used to compare the HSS score and the Knee Society score between primary and revision TKAs. A value ofP 〈 0.05 was considered statistically significant. Results： Four knees （two patients） were lost to follow-up, and 47 knees （31 primary TKAs and 16 revision TKAs） had a mean follow-up time of 5,5 years. The mean HSS score improved from 51.1 ±15.0 preoperatively to 85.3 ± 8.4 points at the final follow-up （P 〈 0.05）. Similar results were observed in terms of the KSKS and KSFS, which improved from 26.0 ± 13.0 to 80.0 ± 12.2 and from 40.0 ± 15.0 to 85.0± 9.3 points, respectively （P 〈 0.05）. No significant difference in the HSS, KSKS, KSFS, or ROM was found between primary and revision TKAs （P 〉 0.05）. Two complications were observed in the revision TKA group （one intraoperative distal lemur fracture and one recurrence of infection） while one complication （infection） was observed in the primary TKA group. No prosthesis loosening, joint dislocation, patella problems, tibial fracture, or nerve injury were observed. Radiolucent lines were observed in 4% of the knees without progressive osteolysis. Conclusions： Second-generation modular CCK prostheses are a safe and practical treatment for both primary and revision knees that cannot be balanced. However, further studies focusing on different types of constrained prostheses are required to validate these results.

CONSTRAINED DENUMERABLE STATE NON-STATIONARY MDPs WITH EXPECTED TOTAL REWARD CRITERION

In this paper, we consider constrained denumerable state non-stationary Markov decision processes (MDPs, for short) with expected total reward criterion. By the mechanics of intro- ducing Lagrange multiplier and using the methods of probability and analytics, we prove the existence of constrained optimal policies. Moreover, we prove that a constrained optimal policy may be a Markov policy, or be a randomized Markov policy that randomizes between two Markov policies, that differ in only one state.

约束总体最小二乘在点云拼接中的应用

在两站点云拼接的大角度空间直角坐标转换问题中,由于拟合靶标球心坐标值在两套扫描测站坐标系下均存在误差,提出基于约束总体最小二乘的点云拼接方法,建立附有约束条件的变量中的误差模型,对观测向量和系数阵同时进行修改。经算例证明,与传统的约束最小二乘法相比,可得到更加合理的模型和更高精度的参数解。

基于约束最小二乘的近空间雷达网定位算法

该文研究了一种基于归一化约束最小二乘的近空间雷达网定位算法。首先将距离与角度信息的非线性方程转换为线性方程,通过一阶Taylor展开分析了噪声对线性方程的影响,然后将定位问题转化为归一化约束总体最小二乘问题,并通过Lagrange函数将其转换为无约束的优化问题,根据定位均方误差最小原则选取加权因子得到定位解,最后进行了定位误差分析,仿真结果表明了该算法的有效性。

基于全成本电价的安全约束经济调度

在智能电网的研究中,人们通常关注电源与负荷的互动以消纳更多的新能源,而电源、负荷对电网资源的利用程度则考虑较少,未能充分发掘源–网–荷三者互动的深层次效益与价值。为此,提出基于全成本电价的电源、电网、负荷的互动模式与方法。对于电源侧,在优化经济调度时考虑输电成本的影响;对于负荷侧,计算基于潮流追踪法的全成本电价,明确负荷对电源和电网资源的使用情况,体现"谁受益,谁承担成本"的原则,并引入需求侧响应体现全成本电价的意义和价值。基于IEEE30节点系统的算例分析验证了文中方法能够根据用户对电网资源利用程度的大小合理地分摊电网的成本,从而提升电网投资与运行的高效性、公平性、有序性与安全性。

基于学习的人脸图像超分辨率重构算法

提出了一种新的基于学习的人脸图像超分辨率重构算法,利用高分辨率图像和低分辨率图像的拓扑结构相似性,将现有的低分辨率人脸图像在低分辨率人脸图像字典中展开,在保持系数不变的同时将字典换为高分辨率人脸图像字典,最终得到待重构的高分辨率人脸图像.在系数估计时,使用主成分分析的方法,同时加入了最小全变分作为约束,算法充分利用了不同人脸图像之间的相似性和人脸图像本身的内部相关性.实验结果表明,结果既保持了对原有图像的忠实性,又比较适合人眼观察.

基于约束总体最小二乘算法的接地网故障诊断新模型

针对变电站接地网实际敷设情况往往与施工图纸有所出入、可能造成诊断结果具有较大误差的情况,在传统电路诊断模型的基础上考虑了接地网腐蚀特性,即地理位置越接近的导体被腐蚀的程度越相近,并提出局部差异性腐蚀指标表示支路电阻腐蚀倍数的相近程度,从而建立了接地网故障诊断的增广线性模型,同时运用基于奇异值分解法分解的最佳降秩逼近定理解决模型中方程组等式两端的不相容性.为校正诊断模型中存在的扰动对诊断结果的影响,采用了基于约束总体最小二乘算法的优化算法,对明晰支路和模糊支路分别迭代,在已知设计模型与实际支路敷设有偏差的情况下得出了较为满意的解.仿真计算结果验证了所提方法的正确性和有效性.

加权总体最小二乘在铁路曲线正矢拟合的应用

针对铁路线路正矢数据特征,考虑自变量、因变量同时存在误差的情况,提出EIV(Error-in-Variables)模型下的加权总体最小二乘法(WTLS)进行曲线拟合。通过分析拟合点贡献的不等确定度以及修正设计矩阵A的列向量分别引入权阵P y、P x、P0,并给出选权迭代算法。经实例证明,WTLS比传统的LS、TLS方法具有更高的拟合精度。

金融资产配置与实体企业全要素生产率:“产融相长”还是“脱实向虚”

选取2007—2015年我国A股上市公司的经验数据,探索当前愈演愈烈的实体企业金融化对于全要素生产率的影响,结果表明:实体企业金融化负向影响全要素生产率,体现为"脱实向虚"而非"产融相长",挤占实业投资以及抑制创新投入是其影响路径;在融资约束更低以及短视性更强的企业样本中,金融化行为的"脱实向虚"效应更加凸显;在企业金融化过程中,配置不同类型的金融资产对于全要素生产率的影响存在结构性差异。研究结论为提振实体经济、提升全要素生产率战略目标的实现,提供了重要的方向性参考。

一种鲁棒的约束总体最小二乘无源定位算法

为解决异常误差导致的机载单站无源定位不准确问题,提出了一种鲁棒的约束总体最小二乘(RCTLS)定位算法.首先建立定位模型,构建了加权的约束总体最小二乘(WCTLS)定位准则,并给出了牛顿迭代解.然后,利用广义M估计原理构建了WCTLS准则的鲁棒极值函数,将鲁棒CTLS问题转化为对等价权函数的设计问题,并根据丹麦法构建了等价权函数.理论分析表明,RCTLS算法能够有效识别异常误差,并降低异常测量数据的权值以减小其对定位结果的影响.仿真结果显示,存在异常误差时,RCTLS算法能够获得理想的定位估值,具有较强的鲁棒性.

膝关节置换术中内侧副韧带断裂的治疗及随访研究

目的比较膝关节置换术中内侧副韧带(MCL)损伤后采用限制性关节假体或非限制性关节假体患者的术后膝关节功能。方法回顾性研究2005年1月至2010年12月期间膝关节置换术中发生医源性MCL损伤病例19例。术中对MCL损伤均予以缝合修补。术中采用更换限制性膝关节假体者8例(LCCK组),采用术前计划的假体类型不变者11例(LPS组)。采用膝关节功能评分(KSS)评估术后膝关节功能,比较2组有无差异。全部患者均得到随访,术后随访时间5年。结果在末次随访中(60个月),LCCK组膝关节KSS评分为87.4分,而LPS组为93.3分。11例采用非限制性膝关节假体的患者没有因为膝关节不稳定而翻修;2例采用限制性假体的患者因为关节松动而进行了翻修手术。结论在膝关节置换术中发生MCL损伤往往需要修复MCL,膝关节假体类型可能不需要更换为限制性假体。