The Importance of the Shape Parameter in a Bulk Parameterization Scheme to the Evolution of the Cloud Droplet Spectrum during Condensation

The shape parameter of the Gamma size distribution plays a key role in the evolution of the cloud droplet spectrum in the bulk parameterization schemes. However, due to the inaccurate specification of the shape parameter in the commonly used bulk double-moment schemes, the cloud droplet spectra cannot reasonably be described during the condensation process. Therefore, a newly-developed triple-parameter condensation scheme with the shape parameter diagnosed through the number concentration, cloud water content, and reflectivity factor of cloud droplets can be applied to improve the evolution of the cloud droplet spectrum. The simulation with the new parameterization scheme was compared to those with a high-resolution Lagrangian bin scheme, the double-moment schemes in a parcel model, and the observation in a 1.5D Eulerian model that consists of two cylinders. The new scheme with the shape parameter varying with time and space can accurately simulate the evolution of the cloud droplet spectrum. Furthermore, the volume-mean radius and cloud water content simulated with the new scheme match the Lagrangian analytical solutions well, and the errors are steady, within approximately 0.2%.

Parameters in wind-wave frequency spectra and their bearings on spectrum forms and growth

The spectrum variance m0, peak frequency ω0 and peakness factor p are expressed in terms of nondimensional fetch and duration by making use of relations which are derived through comparing and analyzing existing empirical formulas for the growth of significant wave height and period. The main features of spectrum growth as specified by these parameters agree with those of the JONS-WAP experiments. For given wind speed and fetch, the high frequency parts beyond the peaks of shallow water spectra almost coincide with that of the corresponding deep water spectrum, whereas the low frequency parts differ appreciably. The method developed in this paper predicts smaller significant wave height as well as smaller wave period for shallow water spectra in contrast to the theoretical result of Kitaigorodskii ef al, in which the peak frequency, and consequently the significant wave period, remains basically unchanged for different water depths. Spectra are further reduced to a form in which only significant wave height and period are left as parameters, the peakness factor being replaced by the wave steepness through an empirical relation between them. Spectra in this form have been verified by observations.

Parameter Identification of JONSWAP Spectrum Acquired by Airborne LIDAR

In this study, we developed the first linear Joint North Sea Wave Project(JONSWAP) spectrum(JS), which involves a transformation from the JS solution to the natural logarithmic scale. This transformation is convenient for defining the least squares function in terms of the scale and shape parameters. We identified these two wind-dependent parameters to better understand the wind effect on surface waves. Due to its efficiency and high-resolution, we employed the airborne Light Detection and Ranging(LIDAR) system for our measurements. Due to the lack of actual data, we simulated ocean waves in the MATLAB environment, which can be easily translated into industrial programming language. We utilized the Longuet-Higgin(LH) random-phase method to generate the time series of wave records and used the fast Fourier transform(FFT) technique to compute the power spectra density. After validating these procedures, we identified the JS parameters by minimizing the mean-square error of the target spectrum to that of the estimated spectrum obtained by FFT. We determined that the estimation error is relative to the amount of available wave record data. Finally, we found the inverse computation of wind factors(wind speed and wind fetch length) to be robust and sufficiently precise for wave forecasting.

SPECTRUM DISTRIBUTION OF THE SEDOND ORDER GENERALIZED DISTRIBUTED PARAMETER SYSTEMS

Spectrum distribution of the second order generalized distributed parameter system was discussed via the functional analysis and operator theory in Hilbert space. The solutions of the problem and the constructive expression of the solutions are given by the generalized inverse one of bounded linear operator. This is theoretically important for studying the stabilization and asymptotic stability of the second order generalized distributed parameter system.

Spectrum of the Open Asymmetric Simple Exclusion Process with Arbitrary Boundary Parameters

We study the one-dimensional asymmetric simple exclusion process （ASEP） with generic open boundaries （in- cluding current-counting deformation）, and obtain the exact solutions of this ASEP via the off-diagonal Bethe ansatz method. In particular, numerical results for the small size asymmetric simple exclusion process indicate that the spectrum obtained by the Bethe ansatz equations is complete. Moreover, we present the eigenvalue of the totally asymmetric exclusion process and the corresponding Bethe ansatz equations.

Simulation of γ spectrum-shifting based on the parameter adjustment of Gaussian function space

Based on the statistical characteristics of energy spectrum and the features of spectrum-shifting in spectrometry,the parameter adjustment method of Gaussian function space was applied in the simulation of spectrum-shifting.The transient characteristics of energy spectrum were described by the Gaussian function space,and then the Gaussian function space was transferred by parameter adjustment method.Furthermore,the spectrum-shifting in measurement of energy spectrum was simulated.The applied example shows that the parameters can be adjusted flexibly by this method to meet the various requirements in simulation of energy spectrum-shifting.This method was one parameterized simulation method with good performance for the practical application.

The Red Edge Parameters of Different Wheat Varieties Under Different Fertilization and Irrigation Treatments

The dynamics of red edge parameters at different growth stages of wheat canopy was studied. The red edge position moved to the longer wavelength from erecting stage to heading stage, and returned to the original wavelength direction from grain-filling stage to maturity stage. The leaf total nitrogen content (LTN) is positively related to red edge amplitude (d λ red) and NIR platform amplitude (d λNIRP) and the correlation coefficient improved as growth stage extended. The chlorophyll content (TChl) is negatively related to d λ red from erecting stage to the elongation stage, and positively related to d λ red from heading stage to milky maturity stage. TChl is also positively related to d λNIRP. The leaf area index (LAI) is positively related to d λ red and d λNIRP, and the correlation coefficient improved as growth stage extended. It was concluded that d λ red and d λNIRP can be used as the indicators of winter wheat growth state, and guide the fertilization and irrigation decision making. The λNIRF is suitable for derivation of LTN, the d λ red for TChl, and the d λ red or d λNIRP for LAI.

The focus parameters and their correlation from small earthquakes before and after the 1995 Douhe earthquake

Based on seismic source spectrum solution by multi-station and multi-event coda method, applying Brune seismic source model, we have got the source factors and spectra of 48 small earthquakes occurred before and after the Douhe earthquake of October 6 in 1995. The seismic moments, corner frequencies and stress drops are estimated from the Spectra, and their corrclation and variation with time before and after the Douhe ear-thquake are discussed. The results indicate that the source factors show good stability, their peak frequencies and variation with frequencyappear quite similar. Some events with higher stress drops occurred about one year before the Douhe ertquake.Taking into the account that the Stress drop is calculated from seismic moment and frequency, as well as the correlation betwen them, we emphasis that the higher stress drop mentioned here just implies the higher corner frequency than the normal value.

Linear Support Vector Machine Based Inter-harmonic Modeling and Parameter Estimation

There are often system. The high measure many inter-harmonics in power t accuracy of inter-harmonics order, amplitude and initial phase is needed. A new approach is presented for inter-harmonic modeling and parameter estimation based on linear support vector machine （SVM）. Firstly, parameter estimation of linear model is realized based on standard linear SVM. Then, interharmonic model is transformed to a linear model according to trigonometric functions. The approach obtains order of inter-harmonic model with windowed Blackman-Tukey （BT） spectrum analysis, and gets number and frequency of harmonics. Finally, the linear SVM is applied to estimate the inter-harmonic parameters, amplitude and initial phase. The simulation results show that the proposed approach has high precision and good antinoise. The accuracy of three parameters are all higher than 98%.

Ocean wave parameters retrieved directly from compact polarimetric SAR data

We aim to directly invert wave parameters by using the data of a compact polarimetric synthetic aperture radar(CP SAR)and validate the effectiveness of ocean wave parameter retrieval from the circular transmit/linear receive mode andπ/4 compact polarimetric mode.Relevant data from the RADARSAT-2 fully polarimetric SAR on the C-band were used to obtain the compact polarimetric SAR images,and a polarimetric SAR wave retrieval algorithm was used to verify the sea surface wave measurements.Using the data and algorithm,there is no need to estimate complex hydrodynamic modulation transfer functions,even at large radar incidence angles.First,the radar backscattering cross-sections and backscattering cross-section of the radar linearly polarized with any polarization orientation angle were calculated in the two compact polarimetric SAR modes.Then,the wave slopes along the azimuth direction and the range direction were calculated directly using CP SAR data.Finally,we obtained the slope spectrum of the wave from the estimated wave slopes along azimuth and range directions.The wave parameters extracted from the synthetic wave slope spectrum were compared with those obtained from buoy observations of the National Data Buoy Center,verifying a suitable agreement.

Turbulence and Rainfall Microphysical Parameters Retrieval and Their Relationship Analysis Based on Wind Profiler Radar Data

Rainfall is triggered and mainly dominated by atmospheric thermo-dynamics and rich water vapor.Nonetheless, turbulence is also considered as an important factor influencing the evolution of rainfall microphysical parameters. To study such an influence, the present study utilized boundary layer wind profiler radar measurements. The separation point of the radar power spectral density data was carefully selected to classify rainfall and turbulence signals;the turbulent dissipation rate ε and rainfall microphysical parameters can be retrieved to analyze the relationship betweenε and microphysical parameters. According to the retrievals of two rainfall periods in Beijing 2016, it was observed that(1) ε in the precipitation area ranged from 10^(-3.5) to 10^(-1) m^(2) s^(-3) and was positively correlated with the falling velocity spectrum width;(2) interactions between turbulence and raindrops showed that small raindrops got enlarge through collision and coalescence in weak turbulence, but large raindrops broke up into small drops under strong turbulence, and the separation value of ε being weak or strong varied with rainfall attributes;(3) the variation of rainfall microphysical parameters(characteristic diameters, number concentration, rainfall intensity, and water content) in the middle stage were stronger than those in the early and the later stages of rainfall event;(4) unlike the obvious impacts on raindrop size and number concentration, turbulence impacts on rain rate and LWC were not significant because turbulence did not cause too much water vapor and heat exchange.

Study on the Source Parameters of Earthquakes in the Middle Eastern Area of North Tianshan in Xinjiang

By applying the empirical Green＇s function method, we first proved that the source spectra in the middle eastern area of North Tianshan follow the ω^-2 Brune model, and then, on this basis, obtained the source spectra for 105 earthquakes of ML 2.5 - 5.7 in the studied area upon removing the noise, instrument, propagation and site effects in the observational seismic S waveforms. Finally, we determined the source parameters such as the seismic moment, stress drop, source dimension, etc., based on the Brune model. The results show that there is a good linear correlation between scalar seismic moment, M0, and ML, which is Log10 M0 = 1.10 ML ＋ 17.20; The source radii range between 100- 1500m; the stress drop, 1-16MPa with a predominant range of 1 - 10MPa. The relationship of the seismic moment versus corner frequencies indicates that there may exist two source scaling, that is, when M0 〈 4×10^21 dyne. cm （equal to an ML4.0 event）, stress drop is weakly dependent on M0： whereas, when M0 〉 4×10^21 dyne·cm, stress drop is independent of M0.

A Proposed Frequency Spectrum for Fully Developed Wind Waves by Revisiting P-M Spectrum

It is generally believed that the equilibrium range of wind wave spectrum is in the form of the-4 rather than-5 power law.However,in the widely applied P-M spectrum the equilibrium range is given in the form of-5 power law.In the present paper,a spectrum for full development of wind waves is proposed using the form of the Neumann spectrum,but adopting the-4 power law for the equilibrium range.The proposed spectrum has been verified with NDBC buoy data and could be a substitute for the P-M spectrum.

Optical parameters and energy levels splitting of Ho^(3+) in Ho^(3+): GdVO_4

Ho^3＋ ： GdVO4 is a new laser material suitable for high-power laser systems. In this paper we measure the absorption spectra of Ho^3＋ in the sample Ho^3＋： GdVO4. The intensity parameters are calculated by using the Judd-Ofelt theory. Some predicted spectroscopic parameters, such as the spontaneous radiative transition rate, branching ratio and integrated emission cross section are dealt with. And we also compare the optical parameters with those of other materials. From these results, it is found that there are many transitions which have large oscillator strengths and large integrated emission cross sections. Especially the transitions such as ^5 F4 → ^5 I 8, ^5 S2→^5 I8, ^5 F5 → ^5 I8 and ^5 I7 →^ 5 I8 are useful in solid-state lasers and other fields. Finally, we discuss the splitting of the energy levels of Ho^3＋ in the crystal GdVO4 based on the group theory.

APPLICATION OF WEIGHTED NONOSCILLATORY AND NON-FREE-PARAMETER DISSIPATION DIFFERENCE SCHEME IN CALCULATING THE FLOW OF VIBRATING FLAT CASCADE

A dual-time method is introduced to calculate the unsteady flow in a certain vibrating flat cascade. An implicit lower-upper symmetric-gauss-seidel scheme（LU-SGS） is applied for time stepping in pseudo time domains, and the convection items are discretized with the spatial three-order weighted non-oscillatory and non-free-parameter dissipation difference （WNND） scheme. The turbulence model adopts q-co low-Reynolds-number model. The frequency specmuns of lift coefficients and the unsteady pressure-difference coefficients at different spanwise heights as well as the entropy contours at blade tips on different vibrating instants, are obtained. By the analysis of frequency specmuns of lift coefficients at three spanwise heights, it is considered that there exist obvious non-linear perturbations in the flow induced by the vibrating, and the perturbation frequencies are higher than the basic frequency. The entropy contours at blade tips at different times display an intensively unsteady attribute of the flow under large amplitudes.

云南地区介质衰减、场地响应及震源参数研究

利用云南区域地震台网2012-2023年的地震波形记录,采用联合反演方法,获得研究区的介质衰减Q值、67个台站的场地响应以及区内ML2.0以上2819次地震的震源参数。结果显示,在三段地震波几何衰减模型基础上,非弹性衰减模型较准确地反映了云南地区构造复杂、地震活动性较强的特征。在研究区67个台站中,场地响应总体上没有出现明显的放大效应,但存在显著的高频衰减现象。在卓越频段1~6Hz,场地放大倍数大多为1~4倍;在10Hz以上高频段,场地的衰减幅度大多在0~95%之间。其中,12个台站的场地响应值在1附近波动;4个台站的场地响应值在低频段接近1,在高频段放大;5个台站的场地响应值整体上略小于1;46个台站出现低频段稍微放大,高频段衰减的现象。各震源参数的相关性分析结果表明,地方性震级与矩震级、地震矩、应力降、视应力及辐射能量均正相关,与拐角频率负相关。滇西漾濞、盈江、芒市地震余震区及滇南红河断裂南段是中小地震应力释放水平相对较高地区,沿金沙江–红河断裂带,尤其是滇南红河断裂带南段沿线则是高应力降地震集中的区域,说明这里的断层可能受到相对较强的构造剪应力作用。

基于开关瞬态高频振荡特征的寄生参数提取原理与实现方法研究

寄生参数是影响电力电子系统安全运行与效率优化的重要因素。该文提出一种基于开关瞬态高频振荡特征的寄生参数提取方法。与利用开关瞬态中电压、电流变化斜率的现有方法相比,基于振荡特征的参数提取方法对开关瞬态波形幅值测量准确度以及通道采样同步等方面的要求低,因此对信号衰减与延迟等问题具有较高的鲁棒性。该文首先对器件关断激发的漏源极之间的瞬态振荡进行详细数学推导。然后,讨论由寄生电感、寄生电容与器件共同构成的二阶以及四阶电路的振荡行为,归纳出参数提取方法并详细讨论对应的硬件与算法设计。为验证所提方法的通用性与有效性,以电力电子全换流回路中各组成部件为对象进行验证。在铜片、叠层母排、母线支撑电容、汇流铜条以及半导体功率模块等部件进行寄生参数提取,实际效果表明该方法能提取10 nH数量级的微量寄生参数,且参数辨识的一致性高,具有操作简明、提取误差小等优势。

基于反射系数谱的配电电缆局部缺陷识别定位

传统配电电缆在局部缺陷识别与精准定位上灵敏度较差,位置范围识别受到限制,为解决现有技术在配电电缆缺陷诊断上存在的不足,提出一种基于反射系数谱的配电电缆局部缺陷识别定位方法。首先依据电缆分布参数模型,获得配电电缆完好状态与存在局部缺陷段的反射系数谱,然后利用广义正交积分法,将反射系数谱的虚部从频域转换到空间域,建立积分诊断图,得到具有直观性的定位图谱,根据积分诊断图实现配电电缆局部缺陷的识别与精准定位,方法适用于同时存在多处电缆缺陷的情况。最后,在实验室50 m长的配电电缆上制作老化与破损两种缺陷,用于验证所提方法的有效性。仿真和实验结果表明,该方法对不同缺陷情况均具有较高的识别精度,定位误差小于0.15 m。

基于宽频阻抗谱BIS的XLPE电缆绝缘电树枝缺陷定位方法

提出了一种改进的宽频阻抗谱BIS方法来定位XLPE电缆中的电树枝缺陷。进行了不同温度下的电树枝实验,以启动不同类型的电树枝。利用矢量网络分析仪测试了电树枝生长过程中的高频电容特性。采用改进的定位算法计算了含有不同类型电树枝缺陷的20m长电缆的定位谱,结果表明切片样品的电容随着电树枝的生长而减小。丛林状电树对电容参数的影响大于松枝状电树枝。在丛林状电树枝的定位谱中发现了一个典型的双峰,在松枝状电树枝的光谱中发现了单个峰。

海浪谱法模拟海面场景仿真参数选取准则

为提升海面场景模拟的物理真实感,本文探讨了仿真参数对海洋粗糙面模拟精确性的影响,并建立了海表模拟中仿真参数的选取准则。依据海浪谱和随机过程统计理论,采用自相关函数研究了海面相关长度随风速变化规律。通过建立海浪蒙特卡罗仿真模型,结合随机粗糙面误差分析,提出了不同风速条件下海面场景仿真参数的选取准则。研究表明:将海表模拟的采样间隔限定在顺风向相关长度的0.1~0.5倍,可显著提高海面场景模拟的精确度;而当海面仿真参数超出上述范围时,可能导致海面场景模拟失真,进而影响其视觉真实感。本文所提出的仿真参数选取标准可为开发航海模拟器提供技术支撑。