动力气囊压垫纠正桡骨远端AO C3.1型骨折手法复位后残余成角移位的有限元分析研究

目的:运用有限元分析方法,对智能气囊小夹板通过动力气囊压垫调整压强纠正桡骨远端手法复位后残余成角移位的角度大小进行量化研究,以期验证智能气囊小夹板纠正残余成角移位的可行性,指导临床创新与应用。方法:采用Mimics 15.0、Imageware 13.0、Ansysworkbench 15.0等有限元分析软件仿真建造桡骨远端AO C3.1型骨折掌侧成角30°移位、旋转成角30°移位模型,通过生物力学云图分布特点,分析其残余移位纠正后的固定稳定性及动力气囊压垫压强,调整压强大小与纠正残余成角移位角度大小的量化关系。结果:残余移位纠正后,腕部生物力学云图分布主要集中在桡腕关节处。纠正5°掌侧成角移位,需要调整气囊压垫的压强大小为4.7 kPa,纠正5°旋转成角为3.3 kPa。结论:智能气囊小夹板可通过动力气囊压垫压强的调整,纠正桡骨远端AO C3.1型骨折手法复位后残余成角移位,且复位后固定稳定,并防止骨折再移位。

Joint estimation of DOA, frequency, and polarization based on cumulants and UCA

A joint estimation algorithm of direction of arrival （DOA）, frequency, and polarization, based on fourth-order cumulants and uniform circular array （UCA） of trimmed vector sensors is presented for narrowband non-Gaussian signals. The proposed approach, which is suitable for applications in arbitrary Gaussian noise environments, gives a closed-form representation of the estimated parameters, without spectral peak searching. An efficient method is also provided for elimination of cyclic phase ambiguities. Simulations are presented to show the performance of the algorithm.

Fracture Assessment for Electron Beam Welded Damage Tolerant Ti-6Al-4V Alloy by the FITNET Procedure

Fracture assessment of the cracked structures is essential to avoiding fracture failure.A number of fracture assessment procedures have been proposed for various steel structures.However,the studies about the application of available procedures for titanium alloy structures are scarcely reported.Fracture assessment for the electron beam(EB) welded thick-walled damage tolerant Ti-6Al-4V(TC4-DT) alloy is performed by the fitness-for-service(FFS) FITNET procedure.Uniaxial tensile tests and fracture assessment tests of the base metal and weld metal are carried out to obtain the input information of assessment.The standard options and advanced options of FITNET FFS procedure are used to the fracture assessment of the present material.Moreover,the predicted maximum loads of compact tensile specimen using FITNET FFS procedure are verified with the experimental data of fracture assessment tests.As a result,it is shown that the mechanical properties of weld metal are inhomogeneous along the weld depth.The mismatch ratio M is less than 10% at the weld top and middle,whereas more than 10% at the weld bottom.Failure assessment lines of standard options are close to that of advanced option,which means that the standard options are suitable for fracture assessment of the present welds.The accurate estimation of the maximum loads has been obtained by fracture assessment of standard options with error less than 6%.Furthermore,there are no potential advantages of applying higher options or mismatch options.Thus,the present welded joints can be treated as homogeneous material during the fracture assessment,and standard option 1 can be used to achieve accurate enough results.This research provides the engineering treatment methods for the fracture assessment of titanium alloy and its EB welds.

Experimental Study on Metal Transfer and Welding Spatter Characteristics of Cellulose Electrode

Welding spatter cause many problems during the welding process and this issue is particularly important for cellulose electrode welding. The hot flying spatter balls often deteriorate the working environment, and decrease the welding efficiency. Many factors affect the welding spatter, and metal transfer behavior is one of the main factors. Many studies concerning the spatter mechanism in arc welding process were made; most of them focused on the solid wire welding and the study on cellulose electrode is rarely reported. In this paper the metal transfer behavior and the weld spatter characteristics of three commercial cellulose electrodes were studied experimentally by using a high speed camera for visually capturing the metal transfer. The relationship between the metal transfer and the welding spatter was analyzed experimentally by comparing the spatter loss coefficient, which is for quantitative evaluation of welding spatter, with the statistical analysis of the large droplet transfer mode. The results showed that short circuiting transfer, large droplet spray transfer, fine droplet spray transfer and explosive transfer govern the metal transfer modes in cellulose electrode welding. Weld spatter occurred mainly in the deflection of large droplet process, explosive transfer process and fine droplet spraying process. Different metal transfer modes lead to different spatter. The deflection of large droplet and explosive transfer are the main factors of the spatter formation. Minimizing the droplet size and reducing the deflection of large droplet and explosive transfer leads to the reduction the amount of spatter in cellulose electrode welding.

Limit Load Solution for Electron Beam Welded Joints with Single Edge Weld Center Crack in Tension

Limit loads are widely studied and several limit load solutions are proposed to some typical geometry of weldments.However,there are no limit load solutions exist for the single edge crack weldments in tension（SEC（T））,which is also a typical geometry in fracture analysis.The mis-matching limit load for thick plate with SEC（T） are investigated and the special limit load solutions are proposed based on the available mis-matching limit load solutions and systematic finite element analyses.The real weld configurations are simplified as a strip,and different weld strength mis-matching ratio M,crack depth/width ratio a/W and weld width 2H are in consideration.As a result,it is found that there exists excellent agreement between the limit load solutions and the FE results for almost all the mis-matching ration M,a/W and ligament-to-weld width ratio（W-a）/H.Moreover,useful recommendations are given for evaluating the limit loads of the EBW structure with SEC（T）.For the EBW joints with SEC（T）,the mis-matching limit loads can be obtained assuming that the components are wholly made of base metal,when M changing from 1.6 to 0.6.When M decreasing to 0.4,the mis-matching limit loads can be obtained assuming that the components are wholly made of base metal only for large value of（W-a）/H.The recommendations may be useful for evaluating the limit loads of the EBW structures with SEC（T）.The engineering simplifications are given for assessing the limit loads of electron beam welded structure with SEC（T）.

α噪声背景下谐波恢复方法研究

为解决α噪声背景下的谐波恢复问题,提出了归一化循环相关结合多重信号分类算法。该算法包含两种多重信号分类算法(MUSIC:Multiple Signal Classification):样本空间MUSIC算法和特征空间MUSIC算法。这两种MUSIC算法充分利用信号子空间和噪声子空间,在空域内做谱峰搜索以求取谐波频率。该算法不仅能估算谐波信号频率,同时也能提高谐波估计的精度。计算机仿真结果表明,使用这两种算法可完成谐波信号频率有效估算,而且效果比原有分数低阶矩及其派生的分数低阶统计量更优,且有效地解决了非整数算子造成的相位扭曲问题,应用前景广泛。

基于“从瘀论治”理论探讨活血化瘀药治疗脑卒中阿司匹林抵抗

在临床上虽规范口服阿司匹林,但仍发生血栓栓塞事件的现象被称为阿司匹林抵抗(AR)。西医应对AR的策略有疗效欠佳、价格昂贵、出血风险高等弊端。现基于“从瘀论治”理论,分析了瘀血在脑卒中AR的形成过程中的重要意义,并系统地探讨了活血化瘀药治疗脑卒中AR的作用机制,旨在提高中医对脑卒中AR的认识,更好地发挥中医药在治疗AR方面的优势。

超声引导下针刺治疗腰臀部肌筋膜疼痛综合征的临床研究

目的:超声引导下针刺肌筋膜疼痛触发点治疗腰臀部肌筋膜疼痛综合征(MPS)的临床疗效观察与评价。方法:选取2020年6月至2020年7月收治的腰臀部肌筋膜疼痛综合征患者30例,采用超声引导下针刺激痛点治疗,观察患者治疗前、首次治疗后和疗程结束后VAS评分,激痛点处弹性模量(E),激痛点与同水平正常组织应变比(SR)。结果:患者VAS治疗前后对比差异有统计学意义(P<0.05);激痛点处弹性模量治疗前、首次治疗与疗程后差异有统计学意义(P<0.05);激痛点与同水平肌肉组织应变比(SR)治疗前、首次治疗与疗程后比较,差异有统计学意义(P<0.05)。结论:超声引导下针刺治疗腰臀部肌筋膜疼痛综合征能改善局部软组织弹性,改变局部形变能力,且具有较好的临床疗效,值得临床推广应用。