Kernel matrix learning with a general regularized risk functional criterion

Kernel-based methods work by embedding the data into a feature space and then searching linear hypothesis among the embedding data points. The performance is mostly affected by which kernel is used. A promising way is to learn the kernel from the data automatically. A general regularized risk functional （RRF） criterion for kernel matrix learning is proposed. Compared with the RRF criterion, general RRF criterion takes into account the geometric distributions of the embedding data points. It is proven that the distance between different geometric distdbutions can be estimated by their centroid distance in the reproducing kernel Hilbert space. Using this criterion for kernel matrix learning leads to a convex quadratically constrained quadratic programming （QCQP） problem. For several commonly used loss functions, their mathematical formulations are given. Experiment results on a collection of benchmark data sets demonstrate the effectiveness of the proposed method.

Wind Power System Risk Assessment Based on Fuzzy Clustering and Copula Function Modeling

According to the characteristics of the correlation of multiple wind farm output, this paper put forwards a modeling method based on fuzzy c-means clustering and the copula function, and correlation wind farms are inserted into IEEE-RTS79 reliability system for risk assessment. By the probabilistic load flow calculated by Monte Carlo simulation method, the probability of the accident is derived, and bus voltage and branch power flow overload risk index are defined in this paper. The results show that this method can realize the modeling of the correlation of wind power output, and the risk index can identify the weakness of the system, which can provide reference for the operation and maintenance personnel.

Risk evaluation of natural disasters based on connection function

There are many uncertain factors,such as stochastic,fuzzy and gray information in the risk analysis on natural hazard.The set pair analysis(SPA)deals effectively with the various uncertain factors contributing to evaluation of the risk level of natural disasters.The evaluation indicators and standards of natural disasters risk are analyzed by identity-discrepancycontrary(IDC).The result,the connection numbers,still has uncertainty information.Thus,yielding the risk evaluation model of natural disasters based on connection function,which construct a set pair relation between the indicators of connection numbers and comprehensive evaluation standards,and describe uncertainty of the connection numbers by using connection function.The study showed that the proposed model takes into account only the uncertainty of risk evaluation indicator identification on natural disasters,also the uncertainty of result connection numbers.This approach gives full consideration to the uncertainty of systematic evaluation process along with the actual meaning of comprehensive evaluation functions.Therefore,this means it is able to reduce the uncertainty of final evaluation results and improve the accuracy and reasonability of evaluation results.This model is capable of reflecting actual situation of the risk evaluation on natural disaster affected by various uncertain factors and has a promotional value in the natural disaster risk assessment.

NONPARAMETRIC ESTIMATION OF BIVARIATE SURVIVAL FUNCTION UNDER THE COMPETING RISKS CASE

Estimation of the bivariate survival function under the competing risks caseis considered.We give an explicit formula for the estimator from a decomposition of thebivariate survival function based on competing risks,which is almost sure consistent.

ON THE EXPECTED DISCOUNTED PENALTY FUNCTION IN A MARKOV-DEPENDENT RISK MODEL WITH CONSTANT DIVIDEND BARRIER

This article considers a Markov-dependent risk model with a constant dividend barrier. A system of integro-differential equations with boundary conditions satisfied by the expected discounted penalty function, with given initial environment state, is derived and solved. Explicit formulas for the discounted penalty function are obtained when the initial surplus is zero or when all the claim amount distributions are from rational family. In two state model, numerical illustrations with exponential claim amounts are given.

Application of Dangerous Probability Function in Risk Estimation of Surface Rupture Earthquake: Taking the Lingwu Fault in Ningxia Region as an Example

Based on the fitting on paleoearthquake data of intra-plate regions in the northern part of China and giving a statistical model of time interdependence, the potential damage earthquakes in a definite future period and characteristics of present shocks along the Lingwu fault have been analyzed by using dangerous probability function and some new data concerned. We have inferred that the fault has entered a period that earthquakes will probably occur. There exists a potential danger that a strong earthquake with M\-S7.0～7.5 will occur in 10～100a.

Association of Fibrin Monomer Polymerization Function, Cerebrovascular Risk Factors and Ischemic Cerebrovascular Disease in Old People

In order to investigate the association of fibrin monomer polymerization function (FMPF) with traditional cerebrovascular risk factors and ischemic cerebrovascular disease in old people. 1∶1 paired case-control comparative study was performed for FMPF and traditional cerebrovascular risk factors on 110 cases of old ischemic cerebrovascular disease and 110 controls matched on age, sex and living condition. The results showed that cerebrovascular risk factors were more prevalent in case group than in control group. In the case group, FMPF was significantly higher than in control group. There was a significant positive correlation between hypertension and fibrin monomer polymerization velocity (FMPV), hypertension and fibrinogen (Fbg), alcohol consumption and Fbg, but no significant correlation between diabetic mellitus, smoking and FMPF was found. Among the parameters of blood lipids, there were significant positive correlations between total cholesterol (TC) and parameters of FMPF to varying degrees, triglycerides (TG) and FMPV, TG and Fbg. Our results also showed there were significant linear trends between TC and FMPV (P<0. 001), TC and Fbg (P=0. 0087), TG and FMPV/Amax (maximum absorbance)(P=0. 0143) respectively. Multiple logistic regression analysis revealed that FMPF in case group remained significantly higher than control group after adjustment of all risk factors that were significant in univariate analysis. It was concluded that there is a possible pathophysiological link between FMPF and cerebrovascular risk factors. An elevated FMPF is associated with ischemic cerebrovascular disease and an independent risk factor of this disease. In old people, detection of FMPF might be a useful screening to identify individuals at increased cerebrothrombotic risk.

Randomized Objective Function Linear Programming in Risk Management

The traditional linear programming model is deterministic. The way that uncertainty is handled is to compute the range of optimality. After the optimal solution is obtained, typically by the simplex method, one considers the effect of varying each objective function coefficient, one at a time. This yields the range of optimality within which the decision variables remain constant. This sensitivity analysis is useful for helping the analyst get a sense for the problem. However, it is unrealistic because objective function coefficients tend not to stand still. They are typically profit contributions from products sold and are subject to randomly varying selling prices. In this paper, a realistic linear program is created for simultaneously randomizing the coefficients from any probability distribution. Furthermore, we present a novel approach for designing a copula of random objective function coefficients according to a specified rank correlation. The corresponding distribution of objective function values is created. This distribution is examined directly for central tendency, spread, skewness and extreme values for the purpose of risk analysis. This enables risk analysis and business analytics, emerging topics in education and preparation for the knowledge economy.

北京社区55~75岁高、低痴呆风险人群身体素质及其认知功能特点

目的分析预测社区中处于生命中期健康老年人痴呆风险因素。方法2021年7月至2023年4月招募北京市两个社区常住1年以上的55~75岁中老年人175例,收集心血管危险因素、衰老和痴呆(CAIDE)相关危险因素和其他一般人口资料,CAIDE风险评分≥9分为高危组,<9分为低危组。采用Stroop色词测验(SCWT)、两元素1-back任务范式、连线测验(TMT)进行评估;测量握力、30 s前臂屈曲测验和5次坐站试验;记录平地步行10 m的平均步速和步长。结果高危组CAIDE总分平均9.86分,低危组4.95分。两组年龄无显著性差异(P=0.188)。男性,受教育程度<7年、收缩压>140 mmHg、胆固醇>6.5 mmol/L、体质量指数>30 kg/m^(2)和缺乏体力活动人群CAIDE痴呆风险评分更高(χ^(2)>3.116,P<0.05)。高危组握力(t=-4.174)、步速(t=-2.414)、SCWT正确率(Z=-2.684)均差于低危组(P<0.05)。Logistic回归分析显示,步速(OR=25.483)、握力(OR=1.133),SCWT正确率(OR=37.430)是痴呆的独立危险因素(P<0.05)。结论握力弱、步速慢、抑制控制能力差可能预示痴呆风险增加。

帕金森病患者出现冻结步态的危险因素分析

目的探讨帕金森病(PD)患者出现冻结步态(FOG)的危险因素。方法选取2019年7月至2022年7月中日友好医院收治的52例PD患者为研究对象,根据是否合并FOG将研究对象分为FOG组(合并FOG,14例)和非FOG组(未合并FOG,38例)。比较分析非FOG组与FOG组患者的临床特征与影像学特征。比较分析非FOG组与FOG组患者的基底前脑功能连接。采用多因素logistic回归方法分析PD患者出现FOG的独立影响因素。结果FOG组患者的国际运动障碍学会统一帕金森病评定量表Ⅱ(MDS-UPDRSⅡ)评分高于非FOG组,差异有统计学意义(P<0.05),且Meynert基底核(Ch4)与双侧中扣带回、中央前回及辅助运动区的功能连接低于非FOG组。多因素logistic回归分析结果显示,MDS-UPDRSⅡ评分、Ch4功能连接是PD患者出现FOG的独立影响因素(P<0.05)。结论MDS-UPDRSⅡ评分升高、Ch4功能连接减弱为PD患者出现FOG的独立影响因素。

聊城市农田土壤污染评价及农业功能分区

为探索聊城市农田土壤污染状况及农业功能分区,以2017~2020年采集的74个表层土样为研究对象,测定了8种重金属元素(Cd、Hg、As、Cu、Pb、Cr、Zn和Ni)、BHC_(s)、DDT_(s)和BaP的含量。依据《土壤环境质量农用地土壤污染风险管控标准》和《绿色食品产地环境质量》作为评价标准,采用污染指数法开展了土壤环境质量评价和农业功能分区研究。采用ANOVA和LSD多重比较,确定了污染物的空间分布差异及其来源。依据山东省土壤背景值进行了重金属潜在生态风险评价。结果表明,除3个DDTs污染样点和1个Cd污染样点外,其他样点均处于清洁水平。在空间分布上,DDTs和Cr含量存在极显著差异,BaP和Hg存在显著差异。农业功能分区结果表明,绿色食品种植区、无公害食品种植区、观察种植区和污染区面积分别占研究区总面积的78.13%、9.45%、6.52%和5.90%。土壤环境生态风险水平以轻微为主,占总面积的77.03%。Hg和Cd在生态风险评估中占有较大比率,应高度警惕和严格监管。

不同术式喉癌患者术后吞咽功能、认知功能的比较及其危险因素分析

目的 分析不同术式喉癌患者术后吞咽功能、认知功能的比较及其危险因素。方法 回顾性选取2020年4月至2023年4月新疆医科大学第一附属医院收治的80例喉癌患者进行研究,根据手术方法不同将患者分为A组(n=26)、B组(n=27)、C组(n=27)。A组行水平半喉切除术,B组行环状软骨-舌骨-会厌固定术(CHEP),C组行垂直半喉切除术。对比三组患者的术后吞咽功能、认知功能,并建立多因素Logistic模型,分析影响术后吞咽功能、认知功能的独立危险因素。结果 C组术后吞咽功能0级率为70.37%,明显高于A(38.46%)、B组(37.04%),差异有统计学意义(P<0.05)。C组术后MOCA、MMSE评分分别为(26.14±2.25)、(27.16±2.14)分,均明显高于A[(24.12±2.34)、(25.14±2.24)分]、B组[(24.45±2.45)、(25.36±2.18)分],差异均有统计学意义(P<0.05)。80例患者的术后吞咽功能障碍发生率为51.25%,认知功能障碍发生率为60.00%。与吞咽功能正常组比较,障碍组年龄≥60岁、TNMⅢ期、颈部淋巴结清扫、气管切开术、水平半喉切除术、CHEP术患者占比较高;与认知功能正常组比较,障碍组年龄≥60岁、初中及以下、水平半喉切除术、CHEP术患者占比较高(P<0.05)。单因素和多因素Logistic分析结果显示,年龄、TNM分期、颈部淋巴结清扫、气管切开术、水平半喉切除术、CHEP术均是导致喉癌患者术后吞咽功能障碍的独立危险因素;年龄、文化程度、水平半喉切除术、CHEP术均是导致喉癌患者术后认知功能障碍的独立危险因素(P<0.05)。结论 垂直半喉切除术手术对喉癌吞咽和认知功能影响较小,水平半喉切除术、CHEP和年龄、文化程度、临床分期等因素均有可能导致喉癌患者引发术后吞咽功能、认知功能障碍。

再植指功能恢复效果的列线图预测模型构建

目的探讨再植指功能恢复差的危险因素,建立患指功能恢复差的预测模型。方法回顾性分析2017年5月至2022年5月在唐山市人民医院行断指再植术的309例(断指376个)手指离断患者的资料,其中男性231例断指274个,女性78例断指102个;年龄19~67岁,平均(41.57±8.59)岁。术后1年对患指功能的恢复效果进行判定,并分成恢复差组和对照组。收集患者一般人口特征、病情信息、手术信息、术前血常规指标行单变量筛查,通过多因素分析确定患指功能恢复差的危险因素,以森林图展现各指标效应大小。依据预测变量构建列线图模型,并通过受试者工作特征(receiver operating characteristic,ROC)曲线下面积(area under curve,AUC)、校准曲线及决策曲线(decision curve analysis,DCA)检验其效能。结果309例(断指376个)患者中,有68例(断指81个)术后功能恢复差,占比21.54%。两组吸烟史、损伤性质、离断程度、离断平面、断指暴露时间、断指保存方式、是否遵医开展康复锻炼情况比较差异有统计学意义(P<0.05)。Logistic回归分析显示,术后患指功能恢复差的危险因素主要为有吸烟史、撕脱伤、离断平面为非末节指骨、断指暴露时间≥8 h、未遵医开展康复锻炼。内部验证显示,AUC为0.819(95%CI:0.762~0.875),模型预测患指功能恢复差的概率与实际概率高度吻合,拟合优度HL检验χ^(2)=7.389,P=0.286。DCA显示模型在风险阈值12%~75%时具有较好的实用性。结论根据有吸烟史、损伤性质、离断平面、断指暴露时间、是否遵医开展康复锻炼构建的列线图模型对断指再植术后患指功能恢复差的预测效果较好。

基于快速进行平方算法的巡检机器人路径规划研究

针对目前快速行进平方法在实际场景中对Sat值选取缺乏评价尺度的问题,提出一种改进的快速行进平方法以应用于巡检机器人的路径规划。该改进方法引入路径评价函数,通过对机器人行驶距离、行驶角度变化量和与障碍物的距离进行无量纲化处理,以获取当前环境下最优的截止阈值参数Sat。构建了PID控制算法,校正了机器人的动作误差。使用MATLAB软件绘制实际运动轨迹,比较相关路径参数。仿真实验表明,改进后的快速行进平方法可根据截止阈值参数Sat生成适用于不同车型和环境特点的最优路径。该研究的改进方法为巡检机器人在实际应用中的路径规划提供了参考。

数据-知识融合的水利工程建设安全风险灰色因子分解机预测模型

【目的】已有的数据驱动的水利工程建设安全风险预测方法对领域知识的挖掘和利用不足,预测结果的准确性和可解释性有待进一步提高。为了构建数据-知识融合的水利工程建设安全风险预测模型,【方法】将灰色聚类与因子分解机相结合,提出了一种融合领域知识的灰色因子分解机。首先,引入基于可能度函数的灰色聚类表征水利工程建设领域专家有关安全风险的先验知识。然后,将先验知识以参数的形式嵌入到因子分解机中,构建出数据-知识融合的灰色因子分解机。最后,基于随机梯度下降构造模型参数的求解算法,并结合实例对模型的有效性进行验证。【结果】实例应用结果显示,与传统因子分解机相比,灰色因子分解机的准确率、精确率、召回率和F_(1)值均得到了不同程度的提升。与支持向量机、深度因子分解机等其他基准模型相比,灰色因子分解机同样具有更好的预测性能。【结论】这表明,数据-知识融合驱动的灰色因子分解机模型能够更加准确地预测出安全风险,从而为水利工程建设安全风险管控提供更好的决策支持。

老年女性急性心肌梗死致心力衰竭的临床特征和危险因素

目的探讨老年女性急性心肌梗死后心力衰竭的临床特点、危险因素,为临床诊治提供参考。方法回顾性分析北京市顺义区医院心血管内科2021年1—12月收治的80例老年急性心肌梗死患者(>60岁)的临床资料,按照性别进行分组后,对比2组临床特点:年龄、就诊时间、心功能分级、心肌酶、B型钠尿肽(N terminal pro B type natriuretic peptide,NT-proBNP)、多支病变比例等,并对心肌梗死患者心力衰竭的相关危险因素进行分析。结果老年女性发病年龄、病程、心梗后心衰发生率,就诊时间高于老年男性(t=5.235、4.644、8.876、14.755,P<0.05),老年女性心功能分级、TnⅠ、NT-proBNP高于老年男性(t=2.330、16.361,P<20.05),老年女性多支病变比例高于老年男性(χ=6.573,P<0.05)。老年女性急性心肌梗死患者发生心力衰竭的主要危险因素为冠心病家族史、高血压、糖尿病、高脂血症(P<0.05)。结论老年女性急性心肌梗死患者发生心力衰竭的危险性高于老年男性,合并冠心病家族史、高血压、糖尿病、高脂血症的患者发生心力衰竭的风险明显增加。

老年急性脑梗死患者术后神经功能恢复不良的影响因素分析

目的分析老年急性脑梗死患者术后神经功能恢复不良的影响因素,并构建风险列线图预测模型。方法选取2021-01—2022-12于发病4.5 h内在济宁医学院附属医院进行静脉溶栓术的174例老年急性脑梗死患者,根据术后神经功能恢复情况分为恢复良好组(n=113)与恢复不良组(n=61),采用Logistic回归分析影响老年急性脑梗死患者术后神经功能恢复的危险因素;采用R软件构建预测老年急性脑梗死患者术后神经功能恢复不良的列线图模型;采用ROC曲线、校准曲线、Hosmer-Lemeshow拟合优度检验评估列线图模型的效能。结果174例老年急性脑梗死患者,61例(35.06%)术后神经功能恢复不良,113例(64.94%)术后神经功能恢复良好。多因素Logistic回归分析显示,糖尿病(95%CI:2.466~21.685,P<0.001)、心房颤动(95%CI:1.485~24.484,P=0.012)、基线NIHSS评分≥12.50分(95%CI:5.945~53.525,P<0.001)、出血性转化(95%CI:1.823~15.328,P=0.002)、责任血管中度狭窄(95%CI:1.686~17.834,P=0.005)、责任血管重度狭窄(95%CI:2.769~40.737,P=0.001)为老年急性脑梗死患者术后神经功能恢复不良的独立危险因素。该列线图模型预测老年急性脑梗死患者术后神经功能恢复不良的ROC曲线下面积0.872(95%CI:0.816~0.928),绘制校准曲线显示预测概率曲线与实际概率曲线基本吻合,且Hosmer-Lemeshow拟合优度检验χ^(2)=7.943,P=0.439。结论糖尿病、心房颤动、基线NIHSS评分≥12.50分、出血性转化、责任血管中/重度狭窄是老年急性脑梗死患者术后神经功能恢复不良的独立危险因素,依此构建的风险列线图预测模型经验有较好的预测效能,能准确、有效预测老年急性脑梗死患者术后神经功能恢复不良发生风险。

我国本土气温指数期货产品的研发设计——源于京津冀“首都经济圈”核心功能区的气温数据

我国幅员辽阔,对天气变化非常敏感,迫切需要对天气风险进行有效管理,以消除或减少天气风险对各行业的不利影响。从产品研发设计视角出发,以京津冀“首都经济圈”核心功能区为例,参考国外成熟产品,对我国本土气温指数期货产品进行合约设计和模拟定价,根据行业需求阐述产品的应用价值,提出产品在天气风险管理中的显著作用。研究贡献有,搭建起我国本土气温指数期货产品的研发体系;基于国外成熟市场规则构建出符合我国国情的气温指数期货产品标准化合约框架;运用ARMA模型构建出精确度高的气温预测模型;采用蒙特卡罗模拟法制定出气温指数期货两款产品价格;明确产品的应用推广需求和风险管理作用。

老年特发性正常压力脑积水患者的姿势稳定性特征

背景:姿势控制能力受损是特发性正常压力脑积水患者发生跌倒、引发继发性损害的重要危险因素,现有研究大多是对患者直线行走时的步态参数进行分析,鲜有对患者在静态与动态活动中的姿势稳定性特征进行分析。目的:分析老年特发性正常压力脑积水患者的姿势稳定性特征。方法:选择2022年9月至2023年2月在上海市复旦大学附属华东医院神经外科临床诊断为特发性正常压力脑积水的患者22例作为患者组,同时选择健康陪诊家属18名作为健康对照组。分别采用计时起立-行走测试、多方向性伸展测试、Berg平衡量表和静态平衡功能测试(反应时间、移动速度、方向控制、最大偏移距离、端点行程)评估受试者的姿势稳定性特征。结果与结论:①患者组完成计时起立-行走测试所需时间及静态平衡功能测试的反应时间均长于健康对照组(P<0.05),前、后、左、右方向上的伸展测试手臂伸展距离均小于健康对照组(P<0.05),Berg平衡量表得分低于健康对照组(P<0.05),静态平衡功能测试的移动速度、方向控制、最大偏移距离和端点行程均小于健康对照组(P<0.05)。②结果提示,特发性正常压力脑积水患者表现出整体的姿势控制能力障碍,反应能力与执行能力受损使得这类患者在面对来自内部或外部的干扰时无法做出及时、准确的运动反应而出现姿势不稳,增加了发生跌倒的风险。

基于不确定性的机坪管制系统风险评估

对机坪管制系统进行风险评估是提高机场安全水平的一个重要措施,但如何科学客观地评价机坪管制系统,得到贴近现实的评估结果是一个难题。基于此,建立了机坪管制系统风险评价体系,从组合权重法的观点出发,通过乘法归一化合成评价权重,并在模糊集理论的基础上引入DS证据论对某机场机坪管制系统进行实例评估,得出人员因素是机坪管制系统安全体系的重点这一结论,对机坪管制系统安全改进有较好的指导意义。