Decoupling of temporal/spatial broadening effects in Doppler wind LiDAR by 2D spectral analysis

Pulse echo accumulation is commonly employed in coherent Doppler wind LiDAR(light detection and ranging)under the assumption of steady wind.Here,the measured spectral data are analyzed in the time dimension and frequency dimension to cope with the temporal wind shear and achieve the optimal accumulation time.A hardware-efficient algorithm combining the interpolation and cross-correlation is used to enhance the wind retrieval accuracy by reducing the frequency sampling interval and then reduce the spectral width calculation error.Moreover,the temporal broadening effect and spatial broadening effect are decoupled according to the strategy we developed.

Analytical Studies of the Cloud Droplet Spectral Dispersion Influence on the First Indirect Aerosol Effect

Atmospheric aerosols （acting as cloud condensation nuclei） can enhance the cloud droplet number concentration and reduce the cloud droplet size, and in turn affect the cloud optical depth, as well as the cloud albedo, and thereby exert a radiative influence on climate （the first indirect aerosol effect）. In this paper, based on various relationships between cloud droplet spectral dispersion （c） and cloud droplet number concentration （Nc）, we analytically derive the corresponding expressions of the cloud radiative forcing induced by changes in the cloud droplet number concentration. Further quantitative evaluation indicates that the cloud radiative forcing induced by aerosols for the different ^-Nc relationships varies from -29.1% to 25.2%, compared to the case without considering spectral dispersion （e = 0）. Our results suggest that an accurate description of e - Nc relationships helps to reduce the uncertainty of the first indirect aerosol effect and advances our scientific understanding of aerosol-cloud-radiation interactions.

Evaluation of Spectral Scale Effects in Estimation of Vegetation Leaf Area Index Using Spectral Indices Methods

Spectral index methodology has been widely used in Leaf Area Index(LAI) retrieval at different spatial scales. There are differences in the spectral response of different remote sensors and thus spectral scale effect generated during the use of spectral indices to retrieve LAI. In this study, PROSPECT, leaf optical properties model and Scattering by Arbitrarily Inclined Layers(SAIL) model, were used to simulate canopy spectral reflectance with a bandwidth of 5 nm and a Gaussian spectral response function was employed to simulate the spectral data at six bandwidths ranging from 10 to 35 nm. Additionally, for bandwidths from 5 to 35 nm, the correlation between the spectral index and LAI, and the sensitivities of the spectral index to changes in LAI and bandwidth were analyzed. Finally, the reflectance data at six bandwidths ranging from 40 to 65 nm were used to verify the spectral scale effect generated during the use of the spectral index to retrieve LAI. Results indicate that Vegetation Index of the Universal Pattern Decomposition(VIUPD) had the highest accuracy during LAI retrieval. Followed by Normalized Difference Vegetation Index(NDVI), Modified Simple Ratio Indices(MSRI) and Triangle Vegetation Index(TVI), although the coefficient of determination R^2 was higher than 0.96, the retrieved LAI values were less than the actual value and thus lacked validity. Other spectral indices were significantly affected by the spectral scale effect with poor retrieval results. In this study, VIUPD, which exhibited a relatively good correlation and sensitivity to LAI, was less affected by the spectral scale effect and had a relatively good retrieval capability. This conclusion supports a purported feature independent of the sensor of this model and also confirms the great potential of VIUPD for retrieval of physicochemical parameters of vegetation using multi-source remote sensing data.

Estimating the site effects in Luoyang basin using horizontal-to-vertical spectral ratio method from a short-period dense array

The influence of local site effects on seismic ground motions is an important issue in seismic hazard assessment and earthquake resistant design. Determining site effects in densely populated cities built on basins can help to reduce the earthquake hazard. Site effects of Luoyang basin are estimated by the horizontal-to-vertical spectral ratio(HVSR) method using ambient noise records from a short-period dense array. The sites in Luoyang basin are sorted into three types according to the pattern of the HVSR curves. There are cases with a single clear peak, two clear peaks, and an unclear low frequency peak or multiple peaks, which correspond to there being one large impedance contrast interface, two large interfaces, and a moderate one beneath the sites, respectively. The site effects characterized by fundamental frequency from HVSR curves are affected by underlying sedimentary layers and depth of sedimentary basement. According to our results, the existence of thick sediment layer obviously lowers the fundamental frequency to the period range from 2 to 4 s in the downtown area of Luoyang city. The ground motion will amplify when through the sites and the buildings with height of 20–50 floors can resonate at the similar frequency domain. Site effects estimation using HVSR method from a short-period dense array is an effective technique in areas of moderate seismic risk where strong motion recordings are lacking, such as the Luoyang basin.

Estimation of spectral responses and chlorophyll based on growth stage effects explored by machine learning methods

Estimation of leaf chlorophyll content(LCC) by proximal sensing is an important tool for photosynthesis evaluation in high-throughput phenotyping. The temporal variability of crop biochemical properties and canopy structure across different growth stages has great impacts on wheat LCC estimation, known as growth stage effects. It will result in the heterogeneity of crop canopy at different growth stages, which would mask subtle spectral response of biochemistry variations. This study aims to explore spectral responses on the growth stage effects and establish LCC models suited for different growth stages. A total number of 864 pairwise samples of wheat canopy spectra and LCC values with 216 observations of each stage were sampled at the tillering, jointing, booting and heading stages in 2021. Firstly, statistical analysis of LCC and spectral response presented different distribution traits and typical spectral variations peak at 470, 520 and 680 nm. Correlation analysis between LCC and reflectance showed typical red edge shifts. Secondly, the testing model of partial least square(PLS) established by the entire datasets to validate the predictive performance at each stage yielded poor LCC estimation accuracy. The spectral wavelengths of red edge(RE) and blue edge(BE) shifts and the poor estimation capability motivated us to further explore the growth stage effects by establishing LCC models at respective growth periods.Finally, competitive adaptive reweighted sampling PLS(CARS-PLS), decision tree(DT) and random forest(RF) were used to select sensitive bands and establish LCC models at specific stages. Bayes optimisation was used to tune the hyperparameters of DT and RF regression. The modelling results indicated that CARS-PLS and DT did not extract specific wavelengths that could decrease the influences of growth stage effects. From the RF out-of-bag(OOB) evaluation, the sensitive wavelengths displayed consistent spectral shifts from BE to GP and from RE to RV from tillering to heading stages. Compared with CARS-PLS and DT,results of RF modelling yielded an estimation accuracy with deviation to performance(RPD) of 2.11, 2.02,3.21 and 3.02, which can accommodate the growth stage effects. Thus, this study explores spectral response on growth stage effects and provides models for chlorophyll content estimation to satisfy the requirement of high-throughput phenotyping.

Quantitative parameters in novel spectral computed tomography:Assessment of Ki-67 expression in patients with gastric adenocarcinoma

BACKGROUND The level of Ki-67 expression has served as a prognostic factor in gastric cancer.The quantitative parameters based on the novel dual-layer spectral detector computed tomography(DLSDCT)in discriminating the Ki-67 expression status are unclear.AIM To investigate the diagnostic ability of DLSDCT-derived parameters for Ki-67 expression status in gastric carcinoma(GC).METHODS Dual-phase enhanced abdominal DLSDCT was performed preoperatively in 108 patients with gastric adenocarcinoma.Primary tumor monoenergetic CT attenuation value at 40-100 kilo electron volt(kev),the slope of the spectral curve(λ_(HU)),iodine concentration(IC),normalized IC(nIC),effective atomic number(Z^(eff))and normalized Z^(eff)(nZ^(eff))in the arterial phase(AP)and venous phase(VP)were retrospectively compared between patients with low and high Ki-67 expression in gastric adenocarcinoma.Spearman’s correlation coefficient was used to analyze the association between the above parameters and Ki-67 expression status.Receiver operating characteristic(ROC)curve analysis was performed to compare the diagnostic efficacy of the statistically significant parameters between two groups.RESULTS Thirty-seven and 71 patients were classified as having low and high Ki-67 expression,respectively.CT_(40 kev-VP),CT_(70 kev-VP),CT_(100 kev-VP),and Z^(eff)-related parameters were significantly higher,but IC-related parameters were lower in the group with low Ki-67 expression status than the group with high Ki-67 expression status,and other analyzed parameters showed no statistical difference between the two groups.Spearman’s correlation analysis showed that CT_(40 kev-VP),CT_(70 kev-VP),CT_(100 kev-VP),Z^(eff),and n Z^(eff) exhibited a negative correlation with Ki-67 status,whereas IC and nIC had positive correlation with Ki-67 status.The ROC analysis demonstrated that the multi-variable model of spectral parameters performed well in identifying the Ki-67 status[area under the curve(AUC)=0.967;sensitivity 95.77%;specificity 91.89%)].Nevertheless,the differentiating capabilities of singlevariable model were moderate(AUC value 0.630-0.835).In addition,the nZ_(VP)^(eff) and nIC_(VP)(AUC 0.835 and 0.805)showed better performance than CT_(40 kev-VP),CT_(70 kev-VP) and CT_(100 kev-VP)(AUC 0.630,0.631 and 0.662)in discriminating the Ki-67 status.CONCLUSION Quantitative spectral parameters are feasible to distinguish low and high Ki-67 expression in gastric adenocarcinoma.Z^(eff) and IC may be useful parameters for evaluating the Ki-67 expression.

Chemical Bond and Spectral Effect of Rare Earth Compound Crystals

The chemical bond parameters and ionic polarizabilities in complex crystals are calculated.The mechanism of host influence on the nephelauxetic effect and hypersensitive transition is discussed.

EQUIVALENT CIRCUIT OF NONLINEAR EFFECT OF SPECTRAL IP

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Nonlinear spectral cleaning effect in cross-polarized wave generation

The underlying mechanism of the spectral cleaning effect of the cross-polarized wave（XPW） generation process was theoretically investigated. This study shows that the spectral noise of an input spectrum can be removed in the XPW generation process and that the spectral cleaning effect depends on the characteristics of the input pulses, such as the chirp and Fourier-transform-limited duration of the initial pulse, and the modulation amplitude and frequency of the spectral noise. Though these factors codetermine the output spectrum of the XPW generation process, the spectral cleaning effect is mainly affected by the initial pulse chirp. The smoothing of the spectrum in the XPW generation process leads to a significant enhancement of the coherent contrast.

Degradation of effective carrier-power-to-noise densityratio based on code trackingspectral sensitivitycoefficient for GNSS radio frequencycompatibilityin C band

The frequency band between 5 010 MHz and 5 030 MHz allocated as C band has been used as a candidate in the global navigation satellite systems （GNSS） along with more and more naviga- tion services in L band. The potential benefits and technical requirements of C band for satellite navi- gation have been analyzed before. However the degradation of effective carrier-power-to-noise densi- ty ratio（ A （C/No ）eu） based on code tracking spectral sensitivity coefficient（ CT_SSC ） as a compati- bility assessment methodology for potential GNSS radio frequency compatibility in C-Band has not been discussed clearly. So the compatibility of the signals in the C band between BeiDou （BD） B1 C and GPS L1C, L1C/A, Galileo E1Os as the interoperability or classical signals in L band is analyzed. Simulation results reveal the interference degree between BD III B1C and GPS L1C/A, L1C, Galileo E1OS. The results can also reveal that the multiplexed binary offset carrier （MBOC） and binary phase shift keying （BPSK） modulation is not appropriate for C band.

Effect of dark soliton on the spectral evolution of bright soliton in a silicon-on-insulator waveguide

The spectral evolution of bright soliton in a silicon-on-insulator optical waveguide is numerically simulated using the split-step Fourier method.The power and input chirp of the dark soliton and the second-order dispersion are varied to investigate the effect of dark soliton on the spectrum of bright soliton.The simulations prove that the dark soliton modifies the spectral shape of the bright soliton.Further,the variation in the power of dark soliton affects the splitting of bright soliton.Furthermore,the chirped dark soliton can improve the spectral width and flatness.The variation in the dispersion of dark soliton modifies the phase matching of the bright soliton and the dispersive wave emission,thereby affecting the spectral evolution.

SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDESⅢ.EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM (Ⅱ) ION

In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence.

核用锆合金管氧化过程中光谱发射率特性研究

发射率在锆合金管非接触测温的准确性和失水事故情况下的传热分析上具有重要意义。本文采集了SZA4、SZA6和ZIRLO 3种锆合金在400,500,600℃下氧化100min过程中4~12μm内的光谱发射率数据,分析了温度、氧化膜厚度和合金组分对材料光谱发射率特性的影响规律。结果表明,3种锆合金在氧化过程中发射率变化趋势基本相同,但组分差异导致在发射率的数值和振荡特性上略有差别。通过建立薄膜干涉模型,解释了光谱发射率在波长方向上的振荡现象,并结合振荡极值与干涉效应原理计算了合金表面氧化膜厚度,在0.6~8μm范围内测量精度达到±0.3μm。

瑞马唑仑用于重症监护病房俯卧位通气深镇静诱导的半数有效剂量

目的测定瑞马唑仑用于重症监护病房(ICU)患者俯卧位通气深镇静诱导的半数有效剂量(ED50)。方法选择2022年11月至2023年7月达州市中心医院收入ICU的早期中、重度急性呼吸窘迫综合征(ARDS)行俯卧位通气深镇静患者45例,给药舒芬太尼0.4μg/kg使重症监护疼痛观察工具(CPOT)评分达0~1分后,使用瑞马唑仑诱导镇静,镇静达标后开始俯卧位通气。瑞马唑仑诱导镇静的剂量由改良Dixon序贯试验法确定,根据预试验确定瑞马唑仑的起始剂量为0.2 mg/kg,剂量梯度为0.025 mg/kg。镇静达标定义为给药后3 min内Richmond躁动-镇静评分(RASS)≤-4分且光谱熵(SE)≤50。但如俯卧位通气3 min之内出现明显的体动、皱眉、流泪、呛咳和吞咽等反应且RASS>-4分或SE>50,仍表示镇静不理想。镇静达标且理想则下一例患者在上一例的给药剂量基础上降低一个梯度,若镇静未达标或不理想,下一例给药剂量升高一个梯度。连续出现10次交叉后终止研究。运用Probit回归分析法,计算出瑞马唑仑的ED50和95%有效剂量(ED95)。记录给药前后心率(HR)、呼吸频率(RR)、平均动脉压(MAP)、血氧饱和度(SpO_(2))及俯卧位通气中心动过缓和恶心呕吐等不良反应的发生情况。结果瑞马唑仑用于ICU患者俯卧位通气深镇静诱导的ED50为0.228 mg/kg(95%CI 0.208~0.248),ED95为0.365 mg/kg(95%CI 0.299-0.518)。与舒芬太尼镇痛达标后(T_(1))比较,瑞马唑仑诱导镇静后2 min(T_(2))和俯卧位通气后2 min(T_(3))各时间点的血氧饱和度(SpO_(2))差异无统计学意义(P>0.05);T_(3)时HR、MAP及RR较T_(1)和T_(2)时均有下降(P<0.05),但下降幅度在20%以内;T_(2)和T_(3)时镇静深度指标RASS及SE比T_(1)时显著下降(P<0.01)。诱导期间3例患者出现低血压,给予麻黄碱有效;2例患者出现心动过缓,给予阿托品有效,无其他不良反应。结论瑞马唑仑用于ICU患者俯卧位通气深镇静诱导的ED50为0.228 mg/kg,ED95为0.365 mg/kg,镇静效果确切,呼吸循环影响较小,不良反应少。

藤黄属植物笼状呫吨酮类化学成分与抗肿瘤作用研究进展

目的为藤黄属植物中笼状呫吨酮类化合物与抗肿瘤作用的研究提供参考。方法以“藤黄属”“笼状呫吨酮”“化学成分”“抗肿瘤作用”为关键词,采用计算机检索中国知网和PubMed数据库中1995年至2023年的相关文献,总结藤黄属植物中分离出的笼状呫吨酮类化合物的化学成分和抗肿瘤作用。结果笼状呫吨酮类化合物为藤黄属植物的特征性化学成分,取代基主要有异戊烯基、异戊二烯基、羧基、羟甲基、甲氧基、羟基等,具有抗肿瘤、抗菌、抗炎等作用,其中抗肿瘤活性研究最广泛。结论笼状呫吨酮类化合物的合理开发和利用可为天然抗肿瘤化合物的筛选提供参考。

不同灯光新型光谱反射诱虫设备诱杀黄曲条跳甲效果研究

新型光谱反射诱虫设备利用昆虫视觉识别,可减少施药量及对环境的不良影响,延缓害虫产生抗药性,在生产中具有较高的推广价值。本研究比较了不同灯光(黑光和白光)新型光谱反射诱虫设备和单用黄色诱虫板对黄曲条跳甲的诱集效果。结果表明,不同灯光(黑光和白光)新型光谱反射诱虫设备处理的诱虫量均高于单用黄色诱虫板处理,其中黑光光谱诱虫设备处理对黄曲条跳甲的诱集效果最好,较白光光谱诱虫设备处理的诱虫量提高18.7%,较单用黄色诱虫板处理的提高47.25%,较单用对照黄色诱虫板处理的提高145.2%。白光光谱诱虫设备处理的诱虫量较单用黄色诱虫板处理的提高24.1%,较单用对照黄色诱虫板提高106.6%。不同灯光(黑光和白光)新型光谱诱虫设备在田间放置10~16 d后进入黄曲条跳甲最佳诱捕期,可及早发现和控制黄曲条跳甲为害;诱杀有效期4周左右。

机器学习辅助光谱分析技术在环境微/纳塑料研究中的应用

微/纳塑料在环境中广泛存在,威胁着全球生态系统的平衡和稳定,因此有必要确定和评估微/纳塑料的环境赋存特征、环境行为和效应以及生态毒性效应。然而微/纳塑料具有的低浓度、小尺寸及容易吸附其他物质等特点,为其在复杂环境基质中的分析带来了巨大挑战。大多数分析方法在提供环境样本中微/纳塑料的定性定量信息方面存在成本高、准确性差、时间效率低等问题,而具有无损、高效、操作方便等优点的光谱分析技术可以弥补这些方法的不足。但采集的微/纳塑料光谱信号可能会受到环境样本中复杂成分的背景噪声干扰,亟需采用智能化手段提高分析的准确性和效率。机器学习具有强大的数据处理和自动化分析能力,准确性高、应用性广,适用于复杂光谱数据的分类和解析,将机器学习与光谱分析技术相结合有望成为微/纳塑料分析的可靠方法。首先对常用的机器学习辅助光谱分析技术进行综述,然后系统性地讨论了机器学习辅助光谱分析技术在微/纳塑料的环境赋存特征、环境行为和效应、生态毒理效应等研究中的应用,最后对该技术的发展前景进行了总结和展望。机器学习辅助光谱分析技术有望为环境中微/纳塑料的生态环境健康风险评估和污染防治提供重要数据支持。

考虑地震波输入差异的二维兰州盆地地震效应研究

利用谱元法和多次透射边界相结合的数值模拟方法,探讨了不同地震波输入时,具有大盆地内嵌小盆地特征的二维兰州盆地构造对地表地震波传播、地表峰值加速度(PGA)及其放大系数,以及频域放大特征等影响,分析了地表地震动的放大特征与盆地横向不均匀构造之间的关系。结果表明:1)当输入波的卓越频率接近小盆地最深处的一阶自振频率时,小盆地发生整体共振现象,进而显著改变地震动或放大系数的分布特征。大盆地边缘形成的次生面波在进入更为松散的小盆地时分化为波速差别显著的两阶面波,且盆地较陡一侧边缘形成的面波强度更大。2)无论何地震波入射,盆地内的最强烈地震动集中于小盆地边缘区域,大盆地较陡一侧边缘上方的区域是次强烈地震动放大区,而盆地基底倾角较缓的一侧边缘区域基本无边缘效应。3)兰州盆地基底形状对地震动的分布特征影响强烈,盆地地表地震动的放大系数受输入波的影响明显。4)水平和垂直分量的地震动及放大系数分布特征差别显著,垂直分量上在大盆地较陡一侧边缘及小盆地内形成两个显著放大区,最强烈放大效应区域靠近小盆地中心,而水平分量上的强烈放大区域主要出现在小盆地内的边缘区域。此外,地表不同位置处的频域放大特征也存在明显差别。

High-level Stark Effect and Spectrum of Spherical Nanometer System

In the electric field and layer-to-layer interaction energy, the law of split-level of high-level Stark effect of spherical nanometer system is explored as well as the frequency of spectrum, intensity and size effect of coefficient of spontaneous radiation. Taking three layers CdS/HgS spherical nanometer system as an example, the influence of the electric field and layer-to- layer interaction energy is explored on Stark effect and spectrum. The results show that in the Stark effect system, the energy level is split based on 1, 3, ..., （2n-1）, when it is in the electric field only, similar to the hydrogen atoms; and in the electric field and layer-to-layer interaction, it is split based on 1, 4, ~ -., n2; with the quantum transition, the frequency of the spectrum decreases with the increasing size of the system; apart from a few spectral lines, the intensity of most spectral lines will decreased as the size increases; while the coefficient of spontaneous radiation will increase with the increasing size; the electric field will cause the changes of spectrum frequency; its spectrum frequency shift is proportional to the square of the electric field intensity; apart from a few spectral lines, the frequency shift of spectral lines that is caused by the electric field and layer-to-layer interaction will decrease as the size increases; the interaction will make the level of electronic energy level lower slightly （the order of magnitude is between 10-7-10-9 eV）, the slightly increased spectrum intensity and the slightly increased value of coefficient of spontaneous radiation, but it will not influence the frequency of spectrum, intensity, and the trend that coefficient of spontaneous radiation changes with the size; when the size is smaller, the layer-to-layer interaction effect will be significant.

空腔效应对集成黑体高温发射率测量影响规律研究

提出集成黑体法中的非等温边界空腔效应修正因子的理论模型。基于有限元思想,开展不同发射率样品、特定温场下的非等温边界空腔效应修正因子理论计算,与基于蒙特卡洛光线追迹法获得的修正因子比对,两者具有良好的一致性,最大偏差不超过2.5%,结果均表明波长越长、样品发射率越低,空腔效应对发射率测量结果影响越大。在1000℃温度下、12~14μm波长范围对铂金材料样品发射率进行实验,并与基于分立黑体法的发射率测量结果比对,经修正后的集成黑体法与分立黑体法的一致性从0.09提升至0.03,该结果验证了引入非等温边界空腔效应修正因子的理论模型的可行性,同时提高了该方法测量发射率的准确性。