考虑柔性和间隙的螺旋引纬机构仿真分析

为了提高引纬机构的稳定性和精度,将柔性构件和间隙的影响考虑在内,联合ANSYS和ADAMS建立螺旋引纬机构的刚柔耦合模型,通过ADAMS进行动力学仿真,在刚性系统和刚柔耦合系统中分别分析了旋转铰间隙对剑杆输出特性曲线的影响。在对仿真数据的观察中发现了相当比例的噪声信号,为了消除噪声信号的影响,利用统计学中上下四分位数和中位数来识别替换异常值;在综合考虑间隙和柔性构件的影响时,利用减噪后的加速度曲线与理想刚体系统下的数据的偏差值得到一个新的曲线,该曲线在固定区间内做高频波动,呈现出类似周期性声波信号的特点。结果表明旋转铰间隙是影响剑杆稳定性和精度的主要因素,柔性构件和间隙的综合作用产生了趋向于周期性的碰撞影响。依据研 究结果可以进一步对原刚体模型下设计的引纬机构进行优化设计。     

光PPM取样信号的最大似然解调

研究了光脉冲位置调制全数字接收机的取样信号的最大似然解调及其性能．对接收到的任意脉冲波形给出了解调算法和差错概率上界。以此为基础,对容易实现的最大累加计数判决算法,讨论了各种参数对其解调性能的影响,其结果对设计和实现全数字ＰＰＭ接收机是有益的。     

同态滤波在扭矩载荷识别中的应用

通过理论分析和实验验证,证明了采用同态滤波的方法识别机器扭矩载荷的可行性。同时提出了根据时序模型的Ｇｒｅｅｎ函数来判定窗函数宽度的方法,减少了选取窗函数宽度的盲目性。作为应用实例,给出了采煤机扭矩的识别结果。     

应用激光透射信号随机波动特性求取颗粒尺寸及浓度

阐述了利用穿越介质后的激光信号的随机波动来测量颗粒尺寸和浓度的原理和方法,并在实验室条件下对标准颗粒进行了验证,实验结果表明,该方法在低颗粒浓度和较高浓度时都能得到的测量结果,建立在该原理上的测量仪器结构简单,对环境要求低,无需特殊的保护措施,这些特点为工业生产中的在线监测提供了一种有效的方法。     

基于SLS技术的非均质材料零件成型研究

基于SLS成型的非均质材料零件是一种变密度材料零件。预热温度和激光能量是影响SLS成型零件烧结密度的主要因素。通过实验调整预热温度和激光能量的参数,然后用MATALB对实验数据进行分析处理,得到烧结密度数学模型,达到对基于SLS成型的非均质材料零件烧结密度进行控制的目的。     

离散频谱分析的一种新校正方法

提出了一种对幅值谱进行校正的新方法,用以解决离散频谱当谱峰没有对正峰顶,有能量泄漏所带来的误差,并讨论了矩形窗、汉宁窗、海明窗和高斯窗四种窗函数的修正方法,校正的频率、幅值和相位的精度可达细化100倍以上的效果。     

锁模半导体激光器产生带宽极限的超短光脉冲

利用主动锁模技术,以光在外腔中的往返频率调制注入电流,在外腔中加入F-P标准具(Fabry-Perot etalon)后,在国內首次获得了带宽极限的可调谐完全锁模半导体激光超短脉冲。该脉冲源可望用于高速光通信、光孤子通信等领域。     

Modeling of Acoustic Signal Energies with a Generalized Frank Copula. A Linguistic Conjecture is Reviewed

In this article a generalized Frank copula was selected to model the dependence between the energy on two frequency bands of the speech signal, coming from eight languages. An algorithm was developed that uses maximum likelihood to choose the best fitting copula’s parameters. Through bootstrap, the algorithm estimates the variability of the parameters for each language and also computes confidence regions by means of Voronoi tesselations. A linguistic conjecture which claims that the languages are organized in three rhythmic classes, was confirmed by the Voronoi regions. Modeling with a uniparametric Frank copula, the different degrees of dependence between the energies were quantified.     

Does age affect the efficacy and safety of GreenLight HPS™ laser photoselective vaporization prostatectomy?

Background: To evaluate the efficacy and safety of GreenLight HPS^? (High Performance System) laser photoselective vaporization prostatectomy (PVP) for the treatment of benign prostatic hyperplasia (BPH) in patients of different age groups. Methods: 164 consecutive patients were stratified into two groups: age <70 (group I, n?=?93) and age ≥70 (group II, n?=?71) years. Transurethral PVP was performed using a GreenLight HPS? side-firing laser system. Voiding parameters were measured preoperatively and at 1 and 4 weeks and 3, 6, 12, 18, 24 and 36 months postoperatively. Results: Among the preoperative parameters evaluated, there were significant differences (p?<?0.05) in prostate volume (I: 58.7; II: 73.6?mL) and serum prostate-specific antigen (I: 1.9; II: 2.9?ng/mL), while American Urological Association Symptom Score (AUASS), Quality of Life (QoL), maximum flow rate (Qmax), Sexual Health Inventory for Men (SHIM) and post void residual (PVR) were similar (p?>?0.05) between groups. No significant differences in laser utilization, energy usage and operating time were noted. Clinical outcomes (AUASS, QoL, Qmax, PVR) showed immediate and stable improvement from baseline (p?<?0.05) within each group, but no significant differences between the two groups were observed during the follow-up period. The incidence of adverse events was low and similar in both groups. Conclusions: The results suggest that age has little effect on the efficacy and safety of GreenLight HPS? laser PVP.