Identification of the Asymmetric Transmission Error and Gear Mesh Dynamic Parameters using Full-Spectrum Responses in a Geared-Rotor System

A dominant source of vibration in geared-rotor systems is the gear mesh fault parameters.They include the asymmetric transmission error(TE),phases of TE,the gear mesh stiffness,the gear mesh damping,and the gear runouts.The present work deals with the experimental identification of the aforementioned parameters.A mathematical model of a geared-rotor system has been developed using Lagrangian dynamics.Equations of motion are transformed into the frequency domain using the full-spectrum response analysis.These transformed equations are used to develop an identification algorithm(IA)based on least-squares fit to estimate the TE and gear mesh dynamic parameters.The system IA is initially verified using numerical simulations.The robustness of the algorithm is checked by introducing white Gaussian noise in the simulated responses.A geared-rotor experimental rig was developed and used to measure responses at gear locations in two orthogonal directions.Measured responses are transformed in the frequency domain using the full-spectrum analysis and used in the present novel IA to identify the gear parameters.The identified parameters are validated by comparing the numerically generated full-spectrum response using experimentally estimated parameters and that from the experimental rig.

Quantitative energy-dispersive X-ray fluorescence analysis for unknown samples using full-spectrum least-squares regression

The full-spectrum least-squares(FSLS) method is introduced to perform quantitative energy-dispersive X-ray fluorescence analysis for unknown solid samples.Based on the conventional least-squares principle, this spectrum evaluation method is able to obtain the background-corrected and interference-free net peaks, which is significant for quantization analyses. A variety of analytical parameters and functions to describe the features of the fluorescence spectra of pure elements are used and established, such as the mass absorption coefficient, the Gi factor, and fundamental fluorescence formulas. The FSLS iterative program was compiled in the C language. The content of each component should reach the convergence criterion at the end of the calculations. After a basic theory analysis and experimental preparation, 13 national standard soil samples were detected using a spectrometer to test the feasibility of using the algorithm. The results show that the calculated contents of Ti, Fe, Ni, Cu, and Zn have the same changing tendency as the corresponding standard content in the 13 reference samples. Accuracies of 0.35% and 14.03% are obtained, respectively, for Fe and Ti, whose standard concentrations are 8.82% and 0.578%, respectively. However, the calculated results of trace elements (only tens of lg/g) deviate from the standard values. This may be because of measurement accuracy and mutual effects between the elements.

Ti_(3)C_(2)T_(x)MXene doped by W atoms for full-spectrum photofixation of nitrogen

Full-spectrum photofixation of N_(2) with remarkable NH_(3) production rate of 228μmol/(g·h)was achieved by W atoms doped Ti_(3)C_(2)T_(x)MXene(W/Ti_(3)C_(2)T_(x)-U)catalyst without sacrificial agents at room temperature.The effects of W doping and ultrasonic intercalation of Ti_(3)C_(2)T_(x)MXene were studied.Scanning transmission electron microscope,electron spin resonance spectra,X-ray photoemission spectroscopy,UV-Vis spectrophotometer,temperature programmed adsorption analyzer and density functional theory calculation were used to characterize the obtained catalysts.Results showed that Ti_(3)C_(2)T_(x)MXene harvested ultraviolet-visible and near-infrared light to generate hot electrons.In addition,the doped W atoms played an effective role in adsorbing and activating N_(2) molecules by donating electrons to the anti-bonding orbital of N_(2) molecules to elongate the bond length of N≡N.

Full-spectrum Bi@SrTiO_(3) for bi-directional promotion effects on photocatalytic redox reaction:Insight into intermediates and mechanism

The development of full-spectrum photocatalysts active in the near-infrared(NIR)region has gained increasing attention for deleterious pollutant removal.The integration of plasmonic metals with semico nductors is an effective way to widen the light re sponse range of photocatalysts due to the strong light absorption and fast plasmonic energy transfer of the localized surface plasmon resonance(LSPR).In this work,the full-spectrum responsive Bi@SrTiO_(3) was prepared via facile solvothermal chemical reduction.The optimal Bi@SrTiO_(3) achieves exceptional photocatalytic Cr(VI)reduction efficiency and tetracycline degradation,realizing bi-directional promotion effects on redox reaction.According to density functional theory(DFT)simulations,the extraordinary photocatalytic performance is attributed to the tunable builtin electric field(IEF)of the Ohmic contact.The favorable adaptability in real water and high stability of BSTO-25 were proved by experime ntal results.And the po ssible photocatalytic mechanism was proposed based on theoretical calculation and experimental results.Furthermore,the non-toxicity of the BSTO-25 was evaluated by E.coli cultivation,which further proves the feasibility of treating wastewater with BSTO-25.This work provides a new perspective on constructing full-spectrum-driven photocatalysts for applications dealing with environmental remediation.

Synthesis and optical properties of highly efficient Na_(3)KMg_(7)(PO_(4))_(6):Eu^(2+)blue phosphor for full-spectrum white-light-emitting diodes:The role of Li_(2)CO_(3)flux

Full-spectrum phosphor-converted white-light-emitting diodes(pc-WLED)are emerging as a mainstream technology in semiconductor lighting.Nevertheless,high-performance blue phosphor which can be excited efficiently by a 400 nm NUV diode chip is still lacking.Herein,we present a blue-emitting Na_(3)KMg_(7)(PO_(4))6:Eu^(2+)phosphor synthesized by the solid-reaction method.Particularly,we find that the using of Li_(2)CO_(3)as flux can significantly improve the crystal quality and thus the emission efficiency of the phosphor.Meanwhile,the excitation peak of the phosphor shifts from 365 to 400 nm,which is pivotal for efficient NUV(400 nm)diode chip excitation.The practical Eu^(2+)concentration is also enhanced by using Li_(2)CO_(3)as flux,and the absorption efficiency is greatly increased.This phosphor exhibits superior PL thermal stability,namely retains 94%integrated photoluminescence intensity at 150℃of that at 25℃.As a result,the optimized phosphor shows an emission band peaked at 437 nm with a bandwidth of 40 nm and a high external photoluminescence quantum yield of 51.7%.Finally,a pc-WLED was fabricated by using NKMPO:Eu^(2+)blue,Sr_(2)SiO_(4):Eu^(2+)green,CaAlSiN_(3):Eu^(2+)red phosphors,and a 400 nm NUV diode chip.It shows a high color rendering index of R_(a)=96.4 and a correlated color temperature of 4358 K.These results prove that NKMPO:Eu^(2+)is a promising blue phosphor for full-spectrum WLED based on NUV diode chips.

Design of luminescence in(Sr,Gd)Li(Al,Mg)_(3)N_(4):Eu^(2+)deep red phosphors via crystal field engineering for full-spectrum WLEDs

Red phosphor,with longer wavelength,is highly desirable for full-spectrum WLEDs.Targeted deep red phosphors(Sr,Gd)Li(AI,Mg)_(3)N_(4):Eu^(2+)were designed from the initial model of SrLiAl_(3)N_(4):Eu^(2+)by structural modification.The correlations among structural evolution,crystal-field environment,and luminescence properties were elucidated.Replacing Sr^(2+)with Gd^(3+)in(Sr,Gd)LiAl_(3)N_(4):Eu^(2+)leads to the enhanced crystal field splitting,larger Stokes shift,and increased structural polyhedron distortion differences,consequently resulting in spectral red-shift and broadening.For further spectral tuning,Mg,with lower electronegativity,was also introduced to modify the local crystal structure,consequently resulting in a further red-shift towards 675 nm and enhanced photoluminescence intensity in(Sr,Gd)Li(AI,Mg)_(3)N_(4):Eu^(2+).What’s more,w-LEDs were fabricated by using blue LED chip,blue,green,red and deep red((Sr,Gd)Li(Al,Mg)_(3)N_(4):Eu^(2+))phosphors whose color rendering index were Ra 96.0 and R997.7.All above results demonstrate that the partial replacements of Sr^(2+)by Gd^(3+)and Al^(3+)by Mg^(2+)are effective methods for spectral modulation and(Sr,Gd)Li(AI,Mg)_(3)N_(4):Eu^(2+)phosphors are suitable for highquality full-spectrum WLEDs.

基于全矢CEEMDAN能量矩和AMHSSA-SVM的滚动轴承故障诊断

为充分利用滚动轴承的故障特征信息,提高故障诊断的准确性和可靠性,文中提出了一种基于全矢自适应噪声完全集成经验模态分解(Complementary Ensemble Empirical Mode Decomposition with Adaptive Noise,CEEMDAN)能量矩和自适应多种群混合麻雀搜索算法(Adaptive Multi-population Hybrid Sparrow Search Algorithm,AMHSSA)优化支持向量机(Support Vector Machine,SVM)的故障诊断方法。首先,采用全矢谱技术融合同源双通道信号;其次,采用CEEMDAN算法处理融合信号,选择相关系数较大的前5阶IMF分量,并计算其能量矩作为支持向量机模型的特征输入;最后,提出AMHSSA算法并优化支持向量机模型的参数,建立AMHSSA-SVM故障诊断模型。对该模型进行测试,结果表明:此模型有效提高了识别准确性,与类似模型对比,进一步证明了其在分类精度和优化时间方面的优越性。

基于全频谱共享的三维轨迹和功率优化方法

当前蜂窝系统频谱资源极度短缺,免授权频谱因而被建议在蜂窝系统中使用。无人机(UAV)的飞行轨迹和功率控制对频谱利用效率有重大影响。然而,基于频谱共享的3维轨迹和功率优化方法却鲜少研究。为此,该文首先提出一种全频谱共享方法,即无人机通过控制上行蜂窝用户和设备到设备(D2D)用户的发射功率,在不影响WiFi设备正常传输的前提下使用免授权频谱;同时无人机也能够在不影响其他下行蜂窝用户的前提下使用授权频谱。然后基于提出的全频谱共享方法,该文构建了无人机电池能量约束下的3维飞行轨迹和发射功率的联合优化问题。为了求解提出的复杂多变量耦合的非凸优化问题,该文采用块坐标下降和连续凸逼近方法将原问题转化为3维轨迹优化和功率控制两个凸优化子问题并迭代求解。大量仿真结果证明提出的基于3维轨迹和功率优化的全频谱共享方法能够显著提高频谱利用效率。

无人机高光谱岩性和矿物识别技术研究

无人机高光谱遥感技术以其高空间分辨率和高光谱分辨率的技术优势,在大比例尺区域地质填图领域可以发挥重要作用。利用无人机搭载全谱段高光谱成像仪(HD_SAVI)获取0.2 m高空间分辨率影像数据,采用经验线性法对所获取数据进行光谱重建,重建后无人机高光谱影像光谱曲线与地面实测光谱曲线谱形基本一致,典型特征吸收峰位置偏差均在1个像元以内。采集岩性样本构建岩性知识库,利用深度学习算法基于无人机高光谱影像数据开展岩性识别;岩性识别结果与大比例尺地质图对比,岩性空间分布基本一致,地质体边界准确且较清晰。参考典型矿物光谱库进行矿物识别。与同一地区CASI/SASI航空高光谱数据地质填图结果进行对比分析,结果表明:两者提取的矿物在空间分布上具有较高的一致性,但无人机低空高光谱影像空间分辨率较高,识别出的矿物种类更加丰富。无人机高光谱遥感技术可以满足无人区、交通不便地区地质勘查,以及重点区或矿区外围等地区大比例尺地质填图的需要。

无人机载CeBr3航空监测系统无限大面源探测能力研究

在核设施发生重大事故后,快速获取事故应急区内的辐射水平,对后续应急决策及救援、保护公众免受辐射危害具有至关重要的意义,核应急航空辐射监测是核应急早期快速获取辐射水平的重要技术手段和方法之一,因此核工业航测遥感中心自主研发了无人机载CeBr3航空监测系统。为准确评估该监测系统的探测能力,文章使用蒙特卡罗方法对该监测系统进行了建模,并通过60Co点源对模型的准确性进行了验证。在此基础上,采用全能谱分析、蒙特卡罗及实验相结合的方法获得监测系统对天然辐射单位能谱,并以核事故后地面受到一个新的137Cs放射性沉降场景为例,计算监测系统在不同测量条件下(天然辐射本底、晶体体积、测量高度)对无限大137Cs面源的探测效率及最小可探测活度浓度。通过模拟及计算监测系统对天然辐射本底及核应急人工放射性核素的单位能谱,准确评估了自研的无人机载CeBr3核应急航空监测系统的探测能力,为后续利用该监测系统开展核与辐射航空监测可提供重要理论依据及数据支撑。

基于全谱非靶向代谢组学技术的川芎不同部位代谢物深度解析

为了深度解析川芎中不同部位代谢物特征,本研究采用高效液相色谱法(HPLC)对川芎的根茎、茎、叶中的活性成分进行含量测定,并整合超高效液相色谱-质谱联用仪(UPLC-MS)和气相色谱-质谱联用仪(GC-MS)的全谱非靶向代谢组学技术,对川芎的根茎、茎和叶的挥发性成分、非挥发性成分进行全面的定性和定量分析。结果表明,川芎根茎中活性成分含量高于茎、叶。川芎的全谱非靶向代谢组学共检出2891个代谢物,总丰度为茎>叶>根茎,各部位化学成分种类相同、含量差异较大,包括氨基酸及其衍生物、萜类、酚酸类等32类化合物。其中LC-MS检出1726个代谢物,GC-MS检出1216个代谢物,两个平台共同检出51个代谢物。对川芎不同部位的差异代谢物进行分析,根茎与茎、根茎与叶、茎与叶中筛选到差异代谢物1683、2054和1844个,差异代谢物总丰度为根茎≈茎>叶。根茎中显著富集含氮化合物、酚类、其他类(糖类、内酯类),茎中的醇、胺类、醚类高度富集,叶中的萜类、酮类、黄酮类高度富集。川芎中大多数活性成分如川芎嗪、阿魏酸、藁本内酯等,呈现根茎>茎>叶的趋势,但茎和叶中也含有含量较高的阿魏酸、欧当归内酯A等重要活性成分,具有较高利用价值。通过KEGG富集分析结果推测差异代谢物可能与次生代谢产物的生物合成等途径相关。本研究深度解析了川芎不同部位的成分积累规律,为川芎资源的合理利用提供了科学依据。

太阳能光热催化制氢研究进展

太阳能光热催化(SPTC)制氢技术是从遵循全光谱太阳能分波段能量禀赋特性出发,利用太阳能短波部分高品位光子的光效应驱动光催化反应,同时利用长波部分低品位光子的热效应驱动热催化反应或者辅助强化光催化制氢,可解决传统热催化的高能耗和光催化的低转化效率问题,实现全光谱太阳能的分波段协调转化高效制氢。本文首先介绍了SPTC的定义与分类,然后详细综述了热效应对光催化以及光效应对热催化的协同强化机制,最后对SPTC技术的发展前景进行展望,以期为该技术更广泛的研究及应用提供指导。

不同波长脉冲LED光源的频率和占空比对植物光合速率和光碳能力的影响

本文分析了脉冲发光二极管(LED)光源的研究进展,制作了不同波长的脉冲LED光源面板;测量了灯面板下方25 cm处光合光子通量密度(PPFD)随光源波长、频率和占空比的变化;在固定光源工作周期条件下,研究了光合速率随频率的变化,发现在不同波长下,植物光合速率具有最佳频率;在固定光源频率条件下,研究了光合速率随占空比的变化,发现在不同的占空比下,植物的光合速率有其最佳的占空周期;由于在固定频率或固定占空比条件下,其PPFD不能随着占空比和频率的变化而保持恒定,因此提出了光碳能力的概念(光碳能力=光合速率⋅PPFD^(-1)=Pn⋅PPFD^(-1),其中Pn为光合速率,其生物学意义是一个光子能量转换多少二氧化碳分子进行光合作用);在固定光源占空比条件下,研究了光碳能力随频率的变化。每种光源,均有对应优化的频率,对应得到此种光源下最大的光合速率;每种光源,均有对应优化的频率,对应得到此种光源下最大的PPFD;每种光源,均有对应优化的频率,对应得到此种光源下最大的光碳能力。本文通过提出光碳能力来衡量植物光照参数与碳减排量之间的对应的关系,希望以后光学设计可以通过优化此参数获得最优化的光照条件来获得最经济的碳减排量。

基于全透射可见-近红外光谱的西瓜糖度在线检测研究

糖度是评价西瓜品质的重要指标之一,影响着西瓜的受欢迎程度和销售价格。但体积大、皮厚的自然生物特征为西瓜糖度的快速、无损评估带来了挑战。为探索西瓜糖度快速无损检测,选择230个西瓜作为试验样本,使用自行研制的全透射可见-近红外光谱系统在线采集西瓜光谱数据,在线检测过程中保持光谱连续检测点在西瓜的赤道部位,并分别测量西瓜整果糖度和中心糖度作为理化糖度参考值。首先对样本在线检测过程中产生的多条光谱数据进行均值化处理,并选取波长范围690~1100 nm的光谱数据,使用蒙特卡洛方法剔除其中的异常样本,使用多种预处理方法(SNV、SG平滑等)对光谱数据优化,并采用SPXY算法划分样本校正集和预测集以减小因西瓜内部糖度分布差异造成的影响;基于优化的光谱数据构建了线性PLSR模型和非线性LS-SVM模型预测西瓜中心糖度和整果糖度。结果表明,基于SNV和SG组合法预处理光谱构建的LS-SVM模型预测西瓜整果糖度效果最好,其校正集相关系数R C=0.92,建模均方根误差RMSEC=0.37°Brix;预测集相关系数R P=0.88,预测均方根误差RMSEP=0.40°Brix。进一步使用特征波段挑选算法(CARS、UVE、SPA等)对光谱数据优化,结果显示构建的模型效果更好,其中使用CARS和UVE组合算法选取的特征波长构建LS-SVM模型预测西瓜整果糖度时效果最好,其校正集相关系数R C=0.94,校正均方根误差RMSEC=0.31°Brix;预测集相关系数R P=0.91,预测均方根误差RMSEP=0.37°Brix,且建模变量从1524个特征变量缩减到39个特征变量。该研究为实际生产中西瓜糖度快速无损检测应用提供了参考。

全机疲劳试验几个问题的探讨

全机疲劳试验是规范要求的保障飞机结构完整性以及满足适航要求的大型、复杂以及持续时间长的地面验证试验。全机疲劳试验的几个重要问题,例如试验目的、载荷谱、持续时间和分散系数等,是飞机设计师/工程师非常关注和充分讨论的问题,其中的分散系数也是研究者研究较多的问题之一。针对近年来完成的多个飞机型号的全机疲劳试验,本文介绍了对上述几个问题的研究和认识,对比了国内外5种型号战斗机的疲劳设计与全机疲劳试验情况,提出了关于全机疲劳试验的工程实用的一些建议。本文的研究可以为其他飞机全机疲劳试验提供有益的参考。

应用GA-RBFNN全光谱水体COD与NO_(3)-N检测方法研究

应用全光谱测量水体化学需氧量(chemical oxygen demand,COD)、硝酸盐氮(NO_(3)-N)浓度等水环境质量指标容易受水质环境影响,检测模型与特征波长一直是全光谱检测推广关注重点。该文提出一种基于遗传算法-径向基神经网络(genetic algorithm-radial basis function neural network,GA-RBFNN)全光谱水体COD与NO_(3)-N浓度检测方法,鉴于GA搜索能力强、随机性高的特点,对预处理后全光谱吸收数据应用GA进行特征波长选取,以RBFNN神经网络留K法训练过程中平均决定系数作为适应度函数,输出最优特征波长与RBFNN神经网络参数进行部署,从而实现水体COD、NO_(3)-N浓度准确测量。最后,开展GA-RBFNN、偏最小二乘(partial least squares,PLS)、GA-PLS、RBFNN四种模型对160组水样的COD、NO_(3)-N浓度检测实验,结果表明GA-RBFNN模型对COD、NO_(3)-N检测平均决定系数、最大误差分别为0.9964、0.9950和3.9%、4.9%,均优于其他模型,方法具有重要推广价值。

全频谱深度认知理论与方法

深入研究了全频谱认知与智能利用领域,强调了现有认知无线电理论和无线电监测技术在特定环境中的优势,指出在面对宽带、瞬变、未知、复杂的电磁环境时存在“认不深”的问题。为解决这一挑战,提出了多维度的深度频谱认知作为未来的发展方向,从信号多维特征与个体本征属性双重维度对辐射源目标进行精准认知。通过探索辐射源目标信号的多域特征,构建辐射源完备表征数据库,实现通信终端的本征属性认知,可以更全面地理解和利用频谱资源。分析了调制域、协议域中信号的调制识别以及协议解析等研究现状;高速目标信号识别和空域定向认知的发展瓶颈及主要研究方向。提供了较为全面的理论和方法,为未来多维度的电磁环境感知和频谱利用奠定了基础。

电泵浦有机发光二极管衬底侧向辐射研究

有机发光二极管衬底侧向辐射光谱与正向辐射光谱相比,存在明显的窄化现象。研究影响器件侧向辐射光谱窄化的因素,进一步减小辐射光谱的线宽,可为电泵浦有机发光二极管激光辐射研究打下基础。本文研究了随有机发光二极管空穴传输层NPB厚度的变化,器件衬底侧向辐射光谱的半高宽、峰位以及偏振特性的变化情况。比较了有机发光二极管衬底边缘两侧蒸镀银膜与未蒸镀银膜时的衬底侧向辐射光谱。研究发现蒸镀银膜时有机发光二极管的衬底侧向辐射光谱半高宽变窄,并且当空穴传输层NPB的厚度为130 nm时,器件衬底侧向辐射光谱半高宽低至14 nm。说明器件衬底两侧存在银膜作为反射镜的情况下,衬底中侧向传播的光将受到光学谐振腔的作用。本文的研究结果为有机发光二极管辐射光谱的窄化和辐射光放大提供了一种新思路。

Full-spectrum responsive photocatalytic activity via non-noble metal Bi decorated mulberry-like BiVO_(4)

Due to its appropriate bandgap(~2.4 e V)and efficient light absorption,bismuth vanadate(Bi VO_(4))shows promising photocatalysis activity.However,the charge carrier recombination and poor electron transmission often induce poor photocatalytic performance.Herein,we report a new method to in-situ synthesize non-noble metal Bi decorated mulberry-like Bi VO_(4)by a two-step calcination process.Comprehensive characterizations reveal that non-noble metal Bi nanoparticles grown in-situ on Bi VO_(4)result in the red-shift of the absorbance edge,greatly extending the light absorption from the ultraviolet into the near-infrared region.The surface plasmon resonance excitation of Bi nanoparticles and synergetic effects between Bi and Bi VO_(4)effectively improve the photocatalytic efficiency and promote the separation of photoinduced electron-hole pairs in mulberry-like Bi VO_(4).Density functional theory(DFT)calculation results further verify that the electrons are transferred from Bi to Bi VO_(4)and the formation of·OH radical in Bi/Bi VO_(4)is attributed to the lower simulated free energy,which supports our experimental outcomes.This work provides a novel strategy to enhance light absorption and promote efficient solar utilization of photocatalysts for practical applications.

Ce^(3+) doped BaLu_(2)Al_(2)Ga_(2)SiO_(12)——A novel blue-light excitable cyan-emitting phosphor with ultra-high quantum efficiency and excellent stability for full-spectrum white LEDs

It is well known that cyan-emitting phosphors play a very important role in full-spectrum white LEDs.A large number of cyan-emitting phosphors have been reported in the past few years,however,most of them can only be effectively excited by near-ultraviolet light.There are very few cyan-emitting phosphors that can be intensively excited by blue light(440 and 470 nm).Here,a novel blue-light excitable cyan-emitting phosphor BaLu_(1.95)Ce_(0.05)Al_(2)Ga_(2)SiO_(12)with excellent performance is reported.The cyan phosphor has a cubic structure in space group Ia3^(-)d with a=1.205379(3)nm,which can be easily obtained through a solid-state reaction pathway.The emission peak of the cyan phosphor is located at 500 nm and its internal quantum efficiency is as high as 90.01%when excited at 455 nm at 25℃.The cyan phosphor exhibits superior resistance against thermal quenching of luminescence,and its intensity at 125℃is as strong as 92.14%of the intensity at room temperature.Meanwhile,it also shows an outstanding resistance against water,where its luminescence intensity is hardly changed after being immersed in pure water for 528 h.The white LED lamp prepared by employing the obtained BaLu_(1.95)-Ce_(0.05)Al_(2)Ga_(2)SiO_(12)as cyan phosphor displays remarkable optical properties with CCT=4441 K,Ra=93.7,CRI=90.4 and CIE 1931(x,y)as(x=0.3648,y=0.3752).The experimental results demonstrate that BaLu_(1.95)Ce_(0.05)Al_(2)Ga_(2)SiO_(12)is a promising cyan-emitting phosphor with great application potential in full-spectrum white LEDs.