Study on the impact of polar stratospheric clouds on high resolution mid-IR limb emission spectra

Satellite observations of polar stratospheric clouds (PSCs) in the mid-infrared by high resolution limb emission spectrometers like the Michelson Interferometer for Passive Atmospheric Sounding have been simulated. For particles with radius the scattered tropospheric radiance accounts for a significant part of the continuum signal and leads to absorption line features overlaid over the stratospheric emission spectrum. The scattered radiance shows a strong dependence on particle size up to about radius with a maximum around 3-4. The contribution of scattered radiation depends heavily on tropospheric cloud coverage and earth surface temperature. Distinction of PSCs of different composition is possible for small particles due to differences in the imaginary part of the refractive index. For particles with radii between 1 and the simulated spectra for various PSC compositions differ due to different real parts of the refractive index. For larger particles no distinction is possible any more. Solar radiance scattered by PSCs is important for wavenumbers larger than about . For a forward scattering geometry with 30° between the position of the sun and the limb viewing direction solar contribution exceeds the terrestrial scattered radiation by about a factor of 10.     

A spectroscopic database for water vapor adapted to spectral properties at high temperature, and moderate resolution

The prediction of infrared spectral radiance from high temperature media such as combustion gases requires spectroscopic data for triatomic molecules like water vapor and carbone dioxyde. At temperature above 2000 K, water vapor spectrum is composed of hundreds of thousands lines making practical computations uneasy. We have set up a spectroscopic database for water vapor, based on three existing lines compilations. This database is well suited to computation of remote sensing spectra where hot gases emission is seen through atmospheric paths. The database enables efficient computation of water vapor spectra between 600 and 6600 cm⁻¹ at moderate spectral resolution (5 cm⁻¹). It has been used to compute parameters of a statistical narrow band model which are used in practical applications.     

The millimeter-wave spectrum of chlorine nitrate (ClONO2): The ν6 vibrational state

The pure rotational spectrum of chlorine nitrate in its v₆ = 1 excited vibrational state has been studied. A total of 2901 lines, with K_a extending to 33 in the ³⁵Cl isotopologue and 30 in the ³⁷Cl isotopologue, respectively, have been recorded and assigned. This analysis, along with our recently reported study of the ν₅/ν₆ν₉ dyad and the improved energy levels of ν₉ reported in this paper, should make possible accurate simulation of the corresponding ν₆ band and its complex hot band structure near 435 cm⁻¹.     

Biclustering Three-Dimensional Data Arrays With Plaid Models

Three-dimensional data arrays (collections of individual data matrices) are increasingly prevalent in modern data and pose unique challenges to pattern extraction and visualization. This article introduces a biclustering technique for exploration and pattern detection in such complex structured data. The proposed framework couples the popular plaid model together with tools from functional data analysis to guide the estimation of bicluster responses over the array. We present an efficient algorithm that first detects biclusters that exhibit strong deviations for some data matrices, and then estimates their responses over the entire data array. Altogether, the framework is useful to home in on and display underlying structure and its evolution over conditions/time. The methods are scalable to large datasets, and can accommodate a variety of dynamic patterns. The proposed techniques are illustrated on gene expression data and bilateral trade networks. Supplementary materials are available online.     

Signal Level Simulation Modeling for Antenna Array of Aperture Synthesis Radiometer Based on the Equivalent Complex Baseband Representations

This paper presents a signal-level simulation model for simulating the process that antenna array of Aperture Synthesis Radiometer (ASR) collecting thermal radiation and transforming thermal radiation signal into radio frequency (RF) signal. By using the equivalent complex baseband signals to represent the practical thermal radiation and RF signals, simulation efficiency is improved significantly. The statistic characteristics of simulation results are found to match the corresponding theoretical analysis well. Results of an imaging simulation experiment show that this model can be employed in ASR system-level simulator design.     

《数学实验》课程建设的认识与实践

我们认为 :数学实验 ,就是对数学进行折腾 .我们提出一些饶有趣味而又有深刻背景的问题 ,让学生尝试自己去解决 ,借助于计算机 ,自己动手去折腾 ,在折腾过程中学习 ,观察现象和结果 ,猜测和验证规律 ,尝试和体验数学的探索、发现和应用     

基于Matlab/Simulink的嫦娥二号探月轨道运动的动态仿真

建立了嫦娥二号卫星在有心力场中做轨道运动的动力学模型,使用MATLAB中的SIMU-LINK仿真工具实现了卫星在不同轨道的运动,并得到了卫星轨道运动的实时高度曲线。     

Spectroscopic requirements for ACCURATE, a microwave and infrared-laser occultation satellite mission

The proposed satellite mission ACCURATE consists of a small constellation of satellites in low Earth orbit, combining microwave occultation for thermodynamic state profiling with infrared-laser occultation for greenhouse gas and line-of-sight wind profiling. The mission aims to detect six greenhouse gas molecules with four additional isotopologues (H₂O, CO₂, CH₄, N₂O, O₃, CO, ¹³CO₂, OC¹⁸O, HDO, and H₂¹⁸O) in the upper troposphere and lower stratosphere in the 4000-5000 cm⁻¹ spectral region. Greenhouse gas profiles will be retrieved to within 1-2% accuracy using a ‘differential’ method, requiring two spectral points for each species - one to sample the spectral line and the other nearby to sample the baseline.An estimation of retrieval errors for the ACCURATE mission reveals that errors in spectroscopic line parameters dominate all other error sources. Poor knowledge of the spectroscopy introduces systematic errors into the retrieved greenhouse gas profiles. Using a simple approach, it was shown that the best line parameters currently available are too large to allow retrievals of greenhouse gases to within the stated ACCURATE mission goals of 1% accuracy for CO₂ and 2% for all other species. Therefore, spectroscopic line parameters for targeted lines need to be improved before the ACCURATE mission can be launched. Requirements have been formulated in this direction, and laboratory experiments outlined that could meet these requirements.     

Remote preparation of a two-particle state using a four-qubit cluster state

We present a scheme of remote preparation of two-particle states using a particular four-qubit cluster state as the quantum channel. The probability of success regarding this preparation scheme is calculated in both general and some particular cases. Our results show that in general such remote state preparation can be realized with a probability of 1/4. But in several special cases, the probability of success can be improved to 1/2 or even 1.