动态心电图心率变异性时阈参数对老年冠心病合并高血压自主神经功能改变的诊断价值

目的探讨动态心电图心率变异性(HRV)时阈参数对老年冠心病(CHD)合并高血压自主神经功能改变的诊断价值。方法选取2021年1月至2023年6月期间上海市金山区朱泾社区卫生服务中心全科医疗科收治的160例老年冠心病患者,所有患者均进行动态心电图检查,收集患者心率变异性时阈参数。根据是否发生自主神经功能改变分为自主神经紊乱组和自主神经正常组,采用多因素Logistic回归分析法明确影响CHD患者合并高血压发生自主神经功能改变的危险因素,并采用受试者工作特征(ROC)曲线分析HRV时阈参数对老年CHD合并高血压自主神经功能改变的诊断价值。结果自主神经紊乱组正常R-R间期的标准差(SDNN),每5min正常R-R间期标准差(SDANN),相邻R-R间期差值>50ms的心搏数占比(PNN50)水平均低于自主神经正常组(P<0.05);自主神经紊乱组有吸烟史占比及收缩压均高于自主神经正常组(P<0.05);Logistic回归分析显示,收缩压,SDNN、SDANN、PNN50是影响CHD合并高血压患者发生自主神经功能改变的危险因素(P<0.05);ROC分析结果显示:SDNN、SDANN、PNN50单独及联合预测自主神经功能改变发生的AUC值(95%CI)分别为0.704(0.627~0.774)、0.673(0.595~0.745)、0.715(0.595~0.745)、0.862(0.798~0.911),3者联合预测效能高于各项单独检测(Z=3.150、3.728、2.911,P<0.05)。结论CHD患者HRV时阈参数异常,其中SDNN、SDANN、PNN50低水平是影响CHD发生的独立危险因素,3者联合对老年冠心病CHD合并高血压患者发生自主神经功能改变具有较高的诊断价值。

需求替代的两产品动态批量最优预测时阈研究

研究了存在需求单向替代的两产品动态批量决策的最优预测时阈问题.构建了包含替代成本、生产转换成本和库存成本在内的成本最小化模型,分析得出在只存在3类再生点(Ⅰ类、Ⅱ类和Ⅲ类)情形下的再生点单调性特征.同时,设计出了多项式时间的前向动态规划算法.运用数值试验分析了最优预测时阈与生产转换成本、替代成本、需求特征(需求增长性和需求波动性等)之间的相互关系,并比较分析了存在替代和不存在替代情形下最优预测时阈的相对大小,发现需求替代将显著增加预测时阈的长度.

需求损失下两产品联合生产动态批量决策及预测时阈

研究需求损失下两产品联合生产(采购)动态批量决策问题.在各周期成本变动情形下分析多周期动态批量决策的预测时阈和决策时阈,构建包含联合启动成本、两产品的单独启动成本、库存持有成本、变动生产成本和需求损失成本在内的成本最小化模型.在最优解结构特性的基础上,设计出前向动态规划算法求解问题,通过建立两产品生产点的单调性和建立生产集,给出求解预测时阈和决策时阈的充分条件.通过数值算例分析预测时阈求解的具体过程,表明所构建模型的有效性.

需求双向替代与生产转换下动态批量决策及预测时阈研究

本文研究了存在需求双向替代和生产转换情形下的两产品动态批量决策和预测时阈问题。构建了包含时变的生产转换成本、替代成本以及两产品的生产成本和库存成本在内的成本最小化模型。在最优解性质的基础上,设计出前向动态规划算法求解问题。利用边际成本分析方法得出两产品生产点及再生点的单调性特征,并建立了相应的两产品再生集,最后给出求解预测时阈和相应的决策时阈的充分条件。运用数值实验分析了需求单向替代和双向替代情形下预测时阈的相对大小、同一周期最多发生一次生产转换与可以发生多次转换情形下预测时阈的相对大小,需求增长性与波动性对预测时阈的影响以及生产转换成本与替代成本同时变动时对预测时阈的影响。发现需求双向替代将增加预测时阈的长度,而同一周期可以发生多次生产转换将降低预测时阈的长度。预测时阈随着生产转换成本的增加而显著递增,随着需求增长参数和需求波动参数以及替代成本的增加而递减。

Batch生产方式下动态批量决策及预测时阈

研究了Batch生产方式下动态批量决策问题。在没有生产外包和有生产外包两种情形下分析了多周期动态批量决策的预测时阈和决策时阈。构建包含生产成本、库存持有成本和生产外包成本在内的成本最小化模型。生产成本包括生产固定成本和变动成本,生产外包成本考虑有固定成本和无固定成本两种情形。在最优解结构特性的基础上,设计出前向动态规划算法求解问题。通过建立生产点的单调性和建立再生集,给出了求解预测时阈和决策时阈的充分条件。最后通过数值实验给出了预测时阈作为基准批量和单位外包成本的函数的变化趋势,预测时阈随着基准批量的增加而增大,随着单位外包成本的增加先递减后不变。

基于跨阈持时的结构疲劳可靠性分析

随机响应过程的多次跨阈分析是结构疲劳可靠性评估的一个关键问题,具有重要的理论价值和现实意义。本文以工程中某些具有Wiener特征的结构应力随机过程为研究对象,在Wiener过程多次跨阈概率分析的基础上,建立了考虑随机响应过程跨阈持时的结构疲劳累积损伤及可靠性分析方法。首先,基于累积损伤与跨阈持时之间的关系,推导了考虑Wiener型随机响应跨阈持时的结构疲劳累积损伤指数。然后,将疲劳累积损伤过程建模为带漂移的Wiener过程,以典型应力-时间谱块为基础推导了Wiener过程的漂移系数μ和扩散系数σ。最后,将任意时刻T下的累积损伤指数建模为服从均值为μT,方差为σ^(2) T的正态分布,并与临界疲劳累积损伤指数建立极限状态方程利用JC法求解疲劳可靠度。采用本文方法对某地铁转向架关键部位不同运营时间下的疲劳可靠度进行了分析,验证了本文算法的正确性。

16—25岁青年人純音听觉阈限的測定——Ⅱ.正常听阈曲綫

我們关于青年人純音听觉阈限的測定工作的第二部分,卽現在所要报导的部分,是根据耳机在被試外耳听道中所产生的声压和耳机輸入电压之間的关系(这个关系称为人耳校准的耳机灵敏度)的測定,和工作的第一部分中原有的数据,包括各频率測試起点的耳机輸入电压,和达到听阈时的衰減数字等,計算出各频率上的听阈。

碳排放限额约束下的企业动态生产决策研究

文章在碳排放限额背景下构建了成本最小化模型,并且在此基础上提出相对应的网络流问题,分析得到包括最小成本解等在内的特性,不仅进一步建立了再生集合,而且设计出此研究方向的动态规划方法从而寻找到预测时阈。借助数值仿真方法分析得到多种因素影响了碳排放限额政策背景下的预测时域,并得到在碳排放限额背景下高碳企业当前的生产决策受到今后成本等因素的影响,因此碳排放高的企业在生产决策时取得最优而合理的决策结果,必须综合参考各种影响因素。

The Vegetation Classification of the Return Farmland to Pasture or Forest Region in Shaanxi-Gansu-Ningxia Based on SPOT/VEGETATION Data

In order to assess the climatical and ecological effect which returned the farmland to pasture or forest, the vegetation and crop in Northwest China with suitable threshold value were classified in this experiment by using multi-temporal SPOT/VEGETATION dada and combing supervised classification with unsupervised classification. Compared with the data from Statistical Department and actual investigation, the precision of the classified result was above 85%.

Energy Recovery Threshold Logic and Power Clock Generation Circuits

Energy recovery threshold logic (ERTL) is proposed,which combines threshold logic with adiabatic approach.ERTL achieves low energy as well as low gate complexity.A high efficiency power clock generator is also proposed,which can adjust duty cycle of MOS switch in power clock generator depending on logic complexity and operating frequency to achieve optimum energy efficiency.Closed-form results are derived,which facilitate efficiency-optimized design of the power clock generator.An ERTL PLA and a conventional PLA are designed and simulated on 0.35μm process.The energy efficiency of the proposed power clock generator can reach 77%～85% operating between 20～100MHz.Simulation results indicate that ERTL is a low energy logic.Including power loss of power clock circuits,ERTL PLA still shows 65%～77% power savings compared to conventional PLA.

Debris Flow Warning Threshold Based on Antecedent Rainfall:a Case Study in Jiangjia Ravine,Yunnan,China

Debris flows in Jiangjia Ravine in Yunnan province, China are not only triggered by intense storms but also by short-duration and low-intensity rainfalls. This reflects the significance of antecedent rainfall. This paper tries to find the debris flow- triggering threshold by considering antecedent rainfall through a case study in Jiangjia Ravine. From 23 debris flow events, the I-D （Intensity-Duration） threshold was found, which is very dose to the line of 95th percentile regression line of rainfall events, representing that 95% of rainfalls can potentially induce debris flows and reflects the limitation of I-D threshold application in this area. Taking into account the effect of antecedent rainfall, the debris flowtriggering threshold for rainfall quantity and intensity is statistically and empirically derived. The relationships can be used in debris flow warning system as key thresholds. Coupling with the rainfall characteristics in this area, new thresholds are proposed as triggering and warning thresholds.

Near-duplicate document detection with improved similarity measurement

To quickly find documents with high similarity in existing documentation sets, fingerprint group merging retrieval algorithm is proposed to address both sides of the problem:a given similarity threshold could not be too low and fewer fingerprints could lead to low accuracy. It can be proved that the efficiency of similarity retrieval is improved by fingerprint group merging retrieval algorithm with lower similarity threshold. Experiments with the lower similarity threshold r=0.7 and high fingerprint bits k=400 demonstrate that the CPU time-consuming cost decreases from 1 921 s to 273 s. Theoretical analysis and experimental results verify the effectiveness of this method.

NAND flash service lifetime estimate with recovery effect and retention time relaxation

A service life model of NAND flash and threshold voltage shift process is proposed to calculate the service life and endurance.The relationships among achievable program/erase(P/E) cycles,recovery time,bad block rate and storage time are analyzed.The achievable endurance and service life of a NAND flash are evaluated based on a flash cell degradation and recovery model by varying recovery time,badblock rate,and storage time.It is proposed to improve the service lifetime of solid state disk by both relaxing the bad block rate limitation and retention time while extending the recovery time.The results indicate that endurance can be improved by 17 times if the storage time guarantee is reduced from 10 a to 1 a with 105 s recovery time inserted between cycles.

Energy-Efficient Multi-Mode Clusters Maintenance(M^2CM) for Hierarchical Wireless Sensor Networks

How to energy-efficiently maintain the topology of wireless sensor networks(WSNs) is still a difficult problem because of their numerous nodes,highly dynamic nature,varied application scenarios and limited resources.An energy-efficient multi-mode clusters maintenance(M2CM) method is proposed based on localized and event-driven mechanism in this work,which is different from the conventional clusters maintenance model with always periodically re-clustered among the whole network style based on time-trigger for hierarchical WSNs.M2 CM can meet such demands of clusters maintenance as adaptive local maintenance for the damaged clusters according to its changes in time and space field.,the triggers of M2 CM include such events as nodes' residual energy being under the threshold,the load imbalance of cluster head,joining in or exiting from any cluster for new node or disable one,etc.Based on neighboring relationship of the damaged clusters,one can start a single cluster(inner-cluster) maintenance or clusters(inter-cluster) maintenance program to meet diverse demands in the topology management of hierarchical WSNs.The experiment results based on NS2 simulation show that the proposed method can significantly save energy used in maintaining a damaged network,effectively narrow down the influenced area of clusters maintenance,and increase transmitted data and prolong lifetime of network compared to the traditional schemes.

The Real-Time Arc Protection Circuit for ECRH on HL-2A Tokamak

In 2005 year, SWIP carded through a general engineering and physics experiment of ECRH on HL-2A tokamak. The ECRH protection system is studied and set up to insure the security of ECRH system, and the work is normal. The main protection object of all ECRH system is the gyrotron, and the arc protection for it is more important in the protection system.

Design Near-threshold Photoelectron Imaging Spectrometer Based on UV Laser Induced Photoelectron Emission Anion Source

We have developed a compact photoelectron imaging facility, including an anion source with dissociative photoelectron attachment to molecules, a linear time-of-flight mass spec-trometry （TOFMS）, and an orthogonal high-resolution threshold photoelectron velocity map imaging spectrometer （VMI）. Intense and cold cluster anions were prepared in photoelectron- attachment processes upon pulsed UV laser ablation of metal target. Combining this anion source with TOFMS-VMI, the achieved mass resolution is about 200, and the electron ki- netic energy resolution is better than 3%, i.e., 30 meV for 1 eV electrons. More importantly, low-energy photoelectron imaging spectra for CH3S- and S2- at 611.46 nm are obtained. In both cases, the refined electron affinities are determined to be 1.86264-0.0020 eV for CH3S and 1.67444-0.0035 eV for S2, respectively. Preliminary results suggest that the apparatus is a powerful tool for estimating precise electron affinities values from threshold photoelectron imaging spectroscopy.

High Resolution Crossed Molecular Beams Study of the H+HD→H2+D Reaction

The H+H2 reaction is the simplest chemical reaction system and has long been the prototype model in the study of reaction dynamics. Here we report a high resolution experimental investigation of the state-to-state reaction dynamics in the H+HD→H2+D reaction by using the crossed molecular beams method and velocity map ion imaging technique at the collision energy of 1.17 eV. D atom products in this reaction were probed by the near threshold 1+1'(vacuum ultraviolet+ultraviolet) laser ionization scheme. The ion image with both high angular and energy resolution were acquired. State-to-state differential cross sections was accurately derived. Fast forward scattering oscillations, relating with interference effects in the scattering process, were clearly observed for H2 products at H2(v'=0,j'=1) and H2(v'=0,j'=3) rovibrational levels. This study further demonstrates the importance of measuring high-resolution differential cross sections in the study of state-to-state reaction dynamics in the gas phase.

碳税约束下的企业多周期生产决策研究

碳税政策不仅得到了越来越多的国家或地区应用,也给高碳企业在经营管理中带来了机遇和挑战.研究了碳税政策背景下企业动态批量决策的预测时阈问题.构建了碳税约束下的成本最小化模型并转化为相应的网络流问题,分析得出最优解的特性,在此基础上,构造再生集且设计出前向动态规划算法寻找预测时阈.通过计算以及算例,分析了在碳税政策约束下影响预测时阈的各个因素,并得到碳税政策并不会增加企业的预测时阈,从而不会增加企业的预测成本等重要结论.

基于全国建立碳市场的企业多周期生产决策研究

分析了碳市场政策建立背景下企业动态批量决策的预测时阈问题,构建了碳排放限额与碳交易约束下的成本最小化模型并转化为相应的网络流问题,得出了最优解的特性,进而构造再生集且设计出前向动态规划算法寻找预测时阈。通过计算以及算例,分析了全国建立碳市场政策约束下影响预测时阈的各个因素,得出碳市场政策会增加高碳企业预测时阈等结论。

电声系统测量与分析常用的重要技法——快速傅里叶变换(FFT)

文中主要介绍经常用于电声系统测量和分析的重要技法——快速傅里叶变换(FFT,Fast-Fourier Transform),这种技法在不少电声设备、电声部件、扩声系统及声学系统测量中、相关测试与分析软件的平台上经常出现,如SmaartLive软件和Smaart声学工具软件里的几种模式中。了解并掌握这种技法对顺利实施各个电声指标测量、提高测量精度、圆满完成各种电声测试任务极为重要。