R-Factor Analysis of Data Based on Population Models Comprising R- and Q-Factors Leads to Biased Loading Estimates

Effects of performing an R-factor analysis of observed variables based on population models comprising R- and Q-factors were investigated. Although R-factor analysis of data based on a population model comprising R- and Q-factors is possible, this may lead to model error. Accordingly, loading estimates resulting from R-factor analysis of sample data drawn from a population based on a combination of R- and Q-factors will be biased. It was shown in a simulation study that a large amount of Q-factor variance induces an increase in the variation of R-factor loading estimates beyond the chance level. Tests of the multivariate kurtosis of observed variables are proposed as an indicator of possible Q-factor variance in observed variables as a prerequisite for R-factor analysis.

Increased Q-Factor increases frontal-plane knee joint loading in stationary cycling

Background: Q-Factor(QF), or the inter-pedal width, in cycling is similar to step-width in gait. Although increased step-width has been shown to reduce peak knee abduction moment(KAbM), no studies have examined the biomechanical effects of increased QF in cycling at different workrates in healthy participants.Methods: A total of 16 healthy participants(8 males, 8 females, age: 22.4 ± 2.6 years, body mass index: 22.78 ± 1.43 kg/m^2, mean ± SD) participated.A motion capture system and customized instrumented pedals were used to collect 3-dimensional kinematic(240 Hz) and pedal reaction force(PRF)(1200 Hz) data in 12 testing conditions: 4 QF conditions—Q1(15.0 cm), Q2(19.2 cm), Q3(23.4 cm), and Q4(27.6 cm)—under 3 workrate conditions—80 watts(W), 120 W, and 160 W. A 3 × 4(QF × workrate) repeated measures of analysis of variance were performed to analyze differences among conditions(p < 0.05).Results: Increased QF increased peak KAbM by 47%, 56%, and 56% from Q1 to Q4 at each respective workrate. Mediolateral PRF increased from Q1 to Q4 at each respective workrate. Frontal-plane knee angle and range of motion decreased with increased QF. No changes were observed for peak vertical PRF, knee extension moment, sagittal plane peak knee joint angles, or range of motion.Conclusion: Increased QF increased peak KAbM, suggesting increased medial compartment loading of the knee. QF modulation may influence frontal-plane joint loading when using stationary cycling for exercise or rehabilitation purposes.

Continuous time-varying Q-factor estimation method in the time-frequency domain

The Q-factor is an important physical parameter for characterizing the absorption and attenuation of seismic waves propagating in underground media,which is of great signifi cance for improving the resolution of seismic data,oil and gas detection,and reservoir description.In this paper,the local centroid frequency is defi ned using shaping regularization and used to estimate the Q values of the formation.We propose a continuous time-varying Q-estimation method in the time-frequency domain according to the local centroid frequency,namely,the local centroid frequency shift(LCFS)method.This method can reasonably reduce the calculation error caused by the low accuracy of the time picking of the target formation in the traditional methods.The theoretical and real seismic data processing results show that the time-varying Q values can be accurately estimated using the LCFS method.Compared with the traditional Q-estimation methods,this method does not need to extract the top and bottom interfaces of the target formation;it can also obtain relatively reasonable Q values when there is no eff ective frequency spectrum information.Simultaneously,a reasonable inverse Q fi ltering result can be obtained using the continuous time-varying Q values.

Q-factor estimation in CMP gather and the continuous spectral ratio slope method

The attenuation factor or quality factor(Q-factor or Q) has been used to measure the energy attenuation of seismic waves propagating in underground media. Many methods are used to estimate the Q-factor. We propose a method to calculate the Q-factor based on the prestack Q-factor inversion and the generalized S-transform. The proposed method specifies a standard primary wavelet and calculates the cumulative Q-factors; then, it finds the interlaminar Q-factors using the relation between Q and offset(QVO) and the Dix formula. The proposed method is alternative to methods that calculate interlaminar Q-factors after horizon picking. Because the frequency spectrum of each horizon can be extracted continuously on a 2D time–frequency spectrum, the method is called the continuous spectral ratio slope(CSRS) method. Compared with the other Q-inversion methods, the method offers nearly effortless computations and stability, and has mathematical and physical significance. We use numerical modeling to verify the feasibility of the method and apply it to real data from an oilfield in Ahdeb, Iraq. The results suggest that the resolution and spatial stability of the Q-profile are optimal and contain abundant interlaminar information that is extremely helpful in making lithology and fluid predictions.

Tunable Q-factor wavelet transform denoising with neighboring coefficients and its application to rotating machinery fault diagnosis

Fault diagnosis of rotating machinery is of great importance to the high quality products and long-term safe operation.However,the useful weak features are usually corrupted by strong background noise,thus increasing the difficulty of the feature extraction.Thereby,a novel denoising method based on the tunable Q-factor wavelet transform(TQWT)using neighboring coefficients is proposed in this article.The emerging TQWT possesses excellent properties compared with the conventional constant-Q wavelet transforms,which can tune Q-factor according to the oscillatory behavior of the signal.Meanwhile,neighboring coefficients denoising is adopted to avoid the overkill of conventional term-by-term thresholding techniques.Because of having the combined advantages of the two methods,the presented denoising method is more practical and effective than other methods.The proposed method is applied to a simulated signal,a rolling element bearing with an outer race defect from antenna transmission chain and a gearbox fault detection case.The processing results demonstrate that the proposed method can successfully identify the fault features,showing that this method is more effective than the conventional wavelet thresholding denoising methods,term-by-term TQWT denoising schemes and spectral kurtosis.

High Q-factor controllable phononic modes in hybrid phononic–dielectric structures

Phonon polariton resonances in the mid-infrared spectral range demonstrate properties superior to noble metal-based plasmonics,owing to smaller dissipative loss and better field confinement.However,a conventional way to excite the localized phonon resonance involves ion etching,which reduces the attainable quality factors(Q-factors)of the resonators.We show that by introducing a deep subwavelength layer of dielectric gratings on a phononic substrate,localized dipolar resonance and higher order modes with high Q-factors 96 and 195,respectively,can be excited.We further demonstrate,via experiments and simulations,that the resonant wavelength and field confinement can be controlled by coupling the localized hybrid mode with propagating surface phonon-polaritons.We also observed for the first time the coupling between a localized dipolar mode and a propagating higher-order surface phonon-polariton mode.The results will be useful in designing on-chip,low-loss,and highly integrated phononic devices in the infrared spectral domain.

Analytical Assessment of the Q-Factor due to Cross-Phase Modulation (XPM)

The paper describes the impact of cross-phase modulation on NRZ modulated WDM systems. The impairments due to XPM will be related to a Q-factor and the effects of dispersion management will be covered.

Fabrication and characterization of on-chip silicon spherical-like microcavities with high Q-factors

An effective way to fabricate high-quality(Q)silicon microcavities on-chip is proposed and studied.Our fabrication technique consists of two significant steps:(1)patterning a special silicon micro-pillar by Bosch processes and(2)subsequent reflow of the pillar into a spherical-like microcavity using a laser pulse at 532 nm.Its shape and surface roughness are characterized using a scanning electron microscope and an atomic force microscope.The root-mean-square roughness of the surface is about 0.6 nm.A representative value for the loaded Q-factors of our silicon spherical-like microcavities is on the order of 10^(5).

Q-factor improvement of degenerate four-wave-mixing regenerators for ASE degraded signals

All-optical regenerators can be used to suppress amplified spontaneous emission(ASE) noise introduced by cascaded erbium doped fiber amplifiers(EDFAs) in optical fiber communication systems and lead to the improvement of optical receiver sensitivity. By introducing the Q-factor transfer function(QTF), we evaluate the Q-factor performance of degenerate four-wave mixing(DFWM) regenerators with clock pump and reveal the differences between the optimal input powers determined from the static and dynamic power tranfer function(PTF) and the QTF curves. Our simulation shows that the clock-pump regnerator is capable of improving the Q-facor and receiver sensitivity for 40 Gbit/s ASE-degraded return-to-zero on-off keying(RZ-OOK) signal by 2.58 dB and 4.2 d B, respectively.

基于LMDI和系统聚类的电力行业碳排放影响因素分析

电力行业作为直接使用一次能源的最大部门,是落实我国碳减排目标的重点行业。为厘清电力行业碳排放的主要驱动或抑制来源,论文构建了LMDI模型,从国家及省域两个层面对2006—2020年电力行业碳排放的影响因素进行了分解。研究结果表明,从国家及省域两个层面来看,经济发展效应均为电力碳排放的主要促进因素,火电燃料转化效应和产业结构效应均为电力碳排放的抑制因素,电源结构效应、工业电耗强度效应在全国层面为电力碳排放的抑制因素,但在各省份中的影响效果及程度各有不同。论文以主要抑制因素为变量,利用系统聚类法将30个省份划分为六大区域,针对各区域影响因素的作用效果提出了因地制宜的减排政策。

一种数据库查询的多标签电能质量混合扰动识别与分类新方法

该文针对电能质量混合扰动的复杂性及当前分类识别的准确率不够高等问题,提出一种数据库查询的多标签电能质量混合扰动分类与识别方法,该方法能够更加科学准确地识别混合扰动,可为电能质量治理、扰动事件责任追究等提供有力决策辅助。首先,该方法基于可调Q因子小波变换(tunable Q-factor wavelet transform,TQWT)和时变均方根(rootmeansquare,RMS)的特征提取方法有效提取扰动信号基频时域特征量,较好地克服了当前基频幅值特征提取准确率不够高的难点问题;其次,提出频域特征曲线分割新方法,高效地提取扰动信号的高频特征曲线;然后,建立基频幅值特征数据库和高频特征曲线数据库;最后,利用快速动态时间规整(dynamictimewarping,DTW)结合多标签的分类思想进行混合电能质量扰动的多标签分类。仿真实验结果表明,新方法具有如下优势:几乎不受限值范围内基频偏移的影响,抗噪性较强,对单一扰动及包含双重、三重、四重扰动在内的27种扰动具有较高的分类准确率。电网实测扰动数据的分析,进一步验证了该方法的扰动识别有效性。

基于自适应短时傅里叶变换的品质因子Q值估算方法

品质因子Q是描述地下介质对地震波吸收衰减强弱程度的参数,同时也是地层含油气性的重要标志。在地震资料Q估算中,常用的方法是短时傅里叶变换方法,当窗函数被选定以后,其时频分辨率就固定了。针对该问题,提出一种自适应窗短时傅里叶变换的方法,以获得更准确的瞬时中心频率,并利用峰值频移法来估算品质因子Q。首先,利用固定窗长的短时傅里叶变换来提取信号的瞬时中心频率作为初始频率;然后,根据初始频率自适应计算不同频率的窗长,并利用自适应窗长短时傅里叶变换来求取瞬时中心频率;最后,结合峰值频移法得到高分辨率的品质因子Q值。利用合成数据和实际数据进行了测试,结果表明,相比于固定时窗短时傅里叶变换方法,自适应短时傅里叶变换方法具有更好的时间和频率分辨率,可以获得更高分辨率的品质因子Q值。该结果可以为地下介质的研究提供更准确、可靠的工具,有助于更好地了解地下结构和油气资源分布情况。

重组牛碱性成纤维细胞生长因子凝胶联合调Q激光治疗面部脂溢性角化病

目的:探讨重组牛碱性成纤维细胞生长因子(Recombinant bovine basic fibroblast grow,rb-bFGF)凝胶联合调Q激光治疗面部脂溢性角化病(Seborrheic keratosis,SK)的效果。方法:选笔者医院2020年6月-2023年6月收治的82例面部SK患者为研究对象。按随机数字表法分为对照组(n=41)与观察组(n=41),两组均进行调Q激光治疗(波长532 nm),观察组在对照组基础上给予rb-bFGF凝胶治疗。观察对比两组疗效、疼痛程度、痂皮完全脱落时间、遗留红斑持续时间、皮肤病生活质量量表(Dermatology life quality index,DLQI)及不良反应发生情况。结果:观察组有效率较对照组高,差异有统计学意义(P<0.05);观察组疼痛视觉模拟评分法(Visual analogue scale,VAS)评分较对照组低,创面痂皮完全脱落时间、遗留红斑持续时间均较对照组短,差异均有统计学意义(P<0.05)。治疗后,两组DLQI除治疗维度外其他维度评分均较治疗前降低(P<0.05),且观察组均低于对照组(P<0.05);观察组不良反应发生率为0.93%,对照组为6.03%,差异无统计学意义(P>0.05)。结论:rb-bFGF凝胶联合调Q激光治疗面部SK疗效显著,可促进创面恢复,减轻恢复期疼痛,提高患者生活质量。

三相异步电机匝间短路故障的诊断方法

三相异步电机是各类电机中应用量最大的一种,匝间短路故障为三相异步电机发生概率较大的一类故障。如果能实时监测电机运行状况,对运行进行健康安全评估,将能及时止损,减少损失。提出了基于扩展Clarke变换和故障特征因子Q的匝间故障诊断方法,分析了电机匝间故障的Clarke矢量的特点,对电机匝间故障的Clarke矢量取模,得到三相电流中对称分量的直流分量和2倍于基频的交流分量,以该分量的幅值与直流分量的比值作为故障特征因子Q进行匝间故障诊断。通过特征因子Q研究Clarke矢量频谱,从而判断电机故障,并且进行了理论仿真以及样机测试。

生猪企业价值创造能力提升策略研究——基于13家生猪上市企业的财务数据

企业的最终目标是在经济增长的基础上实现价值创造,头部养猪企业的发展壮大是生猪产业规模化发展的必然。基于13家上市生猪企业2011—2021年的财务数据,利用财务指标和非财务指标计量分析生猪企业的价值创造影响因素,得出资产负债率、净资产收益率和前五大股东持股比例能影响生猪企业的价值创造能力,且资产负债率对价值创造能力的影响最强;公司规模和董事规模会削弱企业价值创造力,其中实际增长率和账面市值比呈非线性关系等结论,并据此从促进企业增长与价值创造的有效协同、建立有效的账务监管体系及强化科技赋能等领域给出了增进价值创造能力的建议。

融合优化可调Q因子小波变换的改进密度峰值聚类算法

为提升时间序列的聚类精度,提出一种融合优化可调Q因子小波变换的改进密度峰值聚类(improved density peaks clustering based on optimal tunable Q-factor wavelet transform,OTQWT-IDPC)算法,该算法利用可调Q因子小波变换的能量优化选择策略及改进粒子群优化算法确定的最佳Q因子分解时序信号,通过最优特征子带的能量、均值、标准差和模糊熵构建特征子空间,并采用主成分分析降低特征维度,以减少特征冗余。同时,考虑到距离较远而周围密集程度较大的K近邻样本对局部密度的贡献率,引入权重系数及K近邻重新定义DPC的局部密度,并利用共享最近邻描述样本间的相似性。在BONN癫痫脑电信号和CWRU滚动轴承数据集上进行对比实验,结果表明,该算法的聚类精度分别为95%、94%,且Jacarrd、FMI和F_(1)值指标均优于其他对比算法,证明了OTQWT-IDPC算法的有效性。

突发脉冲干扰下的白鲸哨声端点检测方法

针对圈养条件下大量突发脉冲干扰影响白鲸哨声检测的问题,提出了一种可调Q因子小波变换(TQWT)结合自适应谱聚类的无监督哨声信号检测方法。对原始信号做高Q因子的小波分解,并以平均小波系数作为检验统计量完成哨声端点粗检测,排除静默时间段与低强度脉冲干扰;在此基础上使用局部密度自适应谱聚类进一步区分哨声与强脉冲干扰,完成白鲸哨声检测。使用实采的白鲸信号测试该检测器性能并计算其F_(1)分数。该检测器在两段测试信号下分别获得了0.9487和0.9429的F_(1)分数,且在大数据量情况下明显优于由k-means聚类或传统谱聚类构成的检测器,具有更高的鲁棒性。

非对称针尖结构对远红外超材料谐振性能的影响研究

为提高远红外超材料的品质因子Q和检测灵敏度,本文研究了一种用于金属远红外超材料的非对称针尖设计。以传统双开口方形谐振环为模型,通过理论模拟,研究了开口狭缝针尖角度变化对其电场分布、谐振频谱以及品质因子Q的影响。结果表明,非对称针尖增强了谐振环的表面电场局域性,减小了谐振峰的半峰全宽,并使品质因子Q提高到传统谐振环(非针尖设计)的三倍以上。该研究结果为开发高灵敏远红外超材料传感器提供了新的思路,并为传统开口谐振环提出了一种简单实用的Q因子优化方法。

薄膜微盘激射性质

基于半导体变形微腔的定向激射效应,在各向同性薄膜中制备变形微腔,将为多功能、高集成光子有源芯片提供新的解决方案.利用二维波动光学理论,以Z切向掺饵铌酸锂薄膜蚶线形微盘中的TE20,1模式为例,分析了不同变形因子ε微盘的模式分布、品质因子Q、定向激射效果D以及庞加莱截面图.理论模拟结果显示,微盘变形过程中微盘周长与谐振波长的比值近似为一定值.当ε大于0.24时,微盘具有较好的单向激射性,Q值大于10^(5);当ε变形因子大于0.4时,庞加莱截面图几乎被混沌海区域占据,Q值低于10^(3).因此,薄膜蚶线形微盘变形因子ε在0.24—0.4之间时,微盘不仅具有高的品质因子(Q值为10^(3)—10^(5)),激射方向性也较高(D值为6.45—8.32).

连续域束缚态赋能的太赫兹超表面:从机理到应用

太赫兹(Terahertz,THz)超表面能够在亚波长尺度下对入射光子进行捕获,并在共振频率处产生强烈的局域场增强效应,表现出卓越的光场操控能力。光子连续域束缚态(Bound states in the continuum,BIC)是位于辐射连续域内的非辐射本征态,具有无限高Q因子和动量空间偏振涡旋两个卓越特性,为在THz超表面中定制高Q共振和增强光场操控带来了新的机遇。本文从回顾光学BIC的历史发展进程出发,综述了周期性光学系统中各类BIC的物理性质及其产生机理,并从拓扑角度着重讨论了BIC的产生及演化规律。此外,着重介绍了BIC赋能的超表面在THz光子学领域的新兴应用,讨论了该领域面临的挑战并对其发展前景作了展望。