Potential of AOD Retrieval Using Atmospheric Emitted Radiance Interferometer (AERI)

Aerosols in the atmosphere play an essential role in the radiative transfer process due to their scattering, absorption, and emission. Moreover, they interrupt the retrieval of atmospheric properties from ground-based and satellite remote sensing. Thus, accurate aerosol information needs to be obtained. Herein, we developed an optimal-estimation-based aerosol optical depth (AOD) retrieval algorithm using the hyperspectral infrared downwelling emitted radiance of the Atmospheric Emitted Radiance Interferometer (AERI). The proposed algorithm is based on the phenomena that the thermal infrared radiance measured by a ground-based remote sensor is sensitive to the thermodynamic profile and degree of the turbid aerosol in the atmosphere. To assess the performance of algorithm, AERI observations, measured throughout the day on 21 October 2010 at Anmyeon, South Korea, were used. The derived thermodynamic profiles and AODs were compared with those of the European center for a reanalysis of medium-range weather forecasts version 5 and global atmosphere watch precision-filter radiometer (GAW-PFR), respectively. The radiances simulated with aerosol information were more suitable for the AERI-observed radiance than those without aerosol (i.e., clear sky). The temporal variation trend of the retrieved AOD matched that of GAW-PFR well, although small discrepancies were present at high aerosol concentrations. This provides a potential possibility for the retrieval of nighttime AOD.

Updated GOES-13 Heliosat-2 Method for Global Horizontal Irradiation in the Americas

Increasing the utilization of renewable energy is at the center of most sustainability policies. Solar energy is the most abundant resource of this type on Earth, and optimizing its use requires the optimal estimation of surface solar irradiation. Heliosat-2 is one of the most popular methods of global horizontal irradiation (GHI) estimation. Originally developed for the Meteosat satellite, Heliosat-2 has been modified in previous work to deal with GOES-13 data and named here GOES_H2. This model has been validated through the computation of indicators and irradiation maps for the Guiana Shield. This article proposes an improved version of GOES_H2, which has been combined with a radiative transfer parameterization (RTP) and the McClear clear-sky model (MC). This new version, hereafter designated RTP_MC_GOES_H2, was tested on eight stations from the Baseline Surface Radiation Network, located in North and South America, and covered by GOES-13. RTP_MC_GOES_H2 improves the hourly GHI estimates independently of the type of sky. This improvement is independent of the climate, no matter the station, the RTP_MC_GOES_H2 gives better results of MBE and RMSE than the original GOES_H2 method. Indeed, the MBE and RMSE values, respectively, change from −11.93% to −2.42% and 23.24% to 18.24% for North America and from −4.35% to 1.79% and 19.97% to 17.37 for South America. Moreover, the flexibility of the method may allow to improve results in the presence of snow cover and rainy/variable weather. Furthermore, RTP_MC_GOES_H2 results outperform or equalize those of other operational models.

ANALYSIS OF THE capabilities OF the CLOSED-OPEN SYSTEM CORRECTION scheme FOR MEASURING VIBRATIONS OF AIRCRAFT STRUCTURal ELEMENTS

В настоящее время в связи со всевозрастающей степенью сложности проектирования, производства и эксплуатации летательных аппаратов все более важным направлением в области развития информационно-измерительных систем становится совершенствование существующих и разработка новых способов измерения параметров вибрации элементов механических конструкций летательных аппаратов. Целью данной работы является анализ возможности и перспективности построения системы для измерения вибраций элементов конструкции самолета на основе использования микромеханических инерциальных измерительных блоков в качестве основных виброметрических измерителей. При этом объектом исследования является система измерения параметров вибрации, а предметом – ее структура, состав, алгоритмы функционирования и ожидаемые точностные характеристики. Для достижения поставленной цели строится информационно-измерительная система на базе инерциальных приборов, а также датчиков для непосредственных измерений перемещений, используются численные и аналитические методы высшей математики и теоретической механики, методы теории случайных процессов и оптимального оценивания. В статье рассмотрены принципы построения такой системы на примере варианта системы измерения параметров вибраций крыла самолета, представлен краткий обзор существующих решений в предметной области и обоснована актуальность и целесообразность предложенного варианта технического решения. Приведены базовый состав и структура системы, описаны основные принципы ее работы, основанные на использовании данных датчиков перемещения, инерциальных измерителей и оптимального калмановского оценивания и коррекции. Показаны основные алгоритмы работы системы, включая алгоритмы ориентации и навигации, оценивания и коррекции при замкнуто-разомкнутой схеме включения оптимального фильтра Калмана, алгоритм вычисления параметров вибрации, представленыматематические модели ошибок основных измерителей системы, показаны полученные предварительные результаты имитационного моделирования, демонстрирующие работоспособность системы и ее ожидаемые приемлемые точностные характеристики, подтверждающие возможность эффективного использования системы и перспективность выбранного направления работ. At present, because of the ever-increasing degree of complexity of aircrafts design, production and operation, the improvement of the existing methods and development of new ones for vibration parameters measurement of aircrafts mechanical structural elements is still an important direction in the field of information-measurement systems development. The purpose of this work is to analyze the possibility and prospects of constructing a system for measuring vibrations of aircraft structural elements based on the use of micromechanical inertial measurement units as the main vibrometric transducers. In this case, the object of research is the vibration parameters measurement system, and the subject is its structure, composition, operations algorithms and the expected accuracy characteristics. To achieve this purpose, an information-measurement system is built on the basis of inertial devices, as well as sensors for direct displacements measurements, numerical and analytical methods of higher mathematics and theoretical mechanics, methods of random processes theory and optimal estimation are used. The article discusses the principles of constructing such system taking as an example a system for measuring the vibration parameters of an aircraft wing, provides a brief overview of the existing solutions in this field of applications and substantiates the relevance and expediency of the proposed methodology of the technical solution. The basic components and structure of the system are presented, the basic principles of its operation are described, based on the use of data from displacement sensors, inertial meters and optimal Kalman estimation and correction. The main algorithms of the system operation are shown, including the orientation and navigation algorithm, estimation and correction algorithm for a closed-open scheme of optimal Kalman filter inclusion in the system, algorithm for calculating vibration parameters, beside the mathematical errors models of the main system sensors and channels are presented, preliminary results of simulation modeling are shown and they demonstrate the operability of the system and its expected acceptable accuracy characteristics, confirming the possibility of the effective use of the proposed system and the prospects of the chosen direction of work.

Optimal Estimation of Thermal Diffusivity in a Thermal Energy Transfer Problem with Heat Generation, Convection Dissipation and Lateral Heat Flow

This work focuses on determining the coefficient of thermal diffusivity in a one-dimensional heat transfer process along a homogeneous and isotropic bar, embedded in a moving fluid with heat generation. A first type (Dirichlet) condition is imposed on one boundary and a third type (Robin) condition is considered at the other one. The parameter is estimated by minimizing the squared errors where noisy observations are numerically simulated at different positions and instants. The results are evaluated by means of the relative errors for different levels of noise. In order to enhance the estimation performance, an optimal design technique is chosen to select the most informative data. Finally, the improvement of the estimate is discussed when an optimal design is used.

Joint Use of in-Scene Background Radiance Estimation and Optimal Estimation Methods for Quantifying Methane Emissions Using PRISMA Hyperspectral Satellite Data: Application to the Korpezhe Industrial Site

Methane (CH4) is one of the most contributing anthropogenic greenhouse gases (GHGs) in terms of global warming. Industry is one of the largest anthropogenic sources of methane, which are currently only roughly estimated. New satellite hyperspectral imagers, such as PRISMA, open up daily temporal monitoring of industrial methane sources at a spatial resolution of 30 m. Here, we developed the Characterization of Effluents Leakages in Industrial Environment (CELINE) code to inverse images of the Korpezhe industrial site. In this code, the in-Scene Background Radiance (ISBR) method was combined with a standard Optimal Estimation (OE) approach. The ISBR-OE method avoids the use of a complete and time-consuming radiative transfer model. The ISBR-OEM developed here overcomes the underestimation issues of the linear method (LM) used in the literature for high concentration plumes and controls a posteriori uncertainty. For the Korpezhe site, using the ISBR-OEM instead of the LM -retrieved CH4 concentration map led to a bias correction on CH4 mass from 4 to 16% depending on the source strength. The most important CH4 source has an estimated flow rate ranging from 0.36 ± 0.3 kg·s−1 to 4 ± 1.76 kg·s−1 on nine dates. These local and variable sources contribute to the CH4 budget and can better constrain climate change models.

Research on the Shearer Positioning Method Based on the MEMS Inertial Sensors/Odometer Integrated Navigation System and RTS Smoother

The shearer positioning method with an inertial measurement unit and the odometer is feasible in the longwall coal-mining process. However, the positioning accuracy will continue to decrease, especially for the micro-electromechanical inertial measurement unit (MIMU). In order to further improve the positioning accuracy of the shearer without adding other external sensors, the positioning method of the Rauch-Tung-Striebel (RTS) smoother-aided MIMU and odometer is proposed. A Kalman filter (KF) with the velocity and position measurements, which are provided by the odometer and closing path optimal estimation model (CPOEM), respectively, is established. The observability analysis is discussed to study the possible conditions under which the error states of KF can be estimated. A RTS smoother with the above-mentioned KF as the forward filter is built. Finally, the experiments of simulating the movement of the shearer through a mobile carrier were carried out, with a longitudinal movement distance of 44.6 m and a lateral advance distance of 1.2 m. The results show that the proposed method can effectively improve the positioning accuracy. In addition, the odometer scale factor and mounting angles can be estimated in real time.

Synthesis of the optimal algorithm and structure of contactless optical device for estimating the parameters of statistically uneven surfaces

The production of parts and (or) finished products in electronics, mechanical engineering and other industries is inextricably linked with the control of the accuracy and cleanliness of the processed surfaces. Currently existing meters of parameters of statistically uneven surfaces, both contact and non-contact have some disadvantages, as well as limitations due to methods and design features of measurement. Speckle interferometric methods for measuring parameters of statistically uneven surfaces make it possible to get away from some disadvantages inherent in existing methods and measurements. The use of methods of statistical radio engineering, methods of optimization of statistical solutions and estimates of parameters of predictive distributions for optimal radio engineering system synthesis is promising for the analysis and processing optical-electronic coherent laser space-time signals (speckle images) form with the laser radiation scattered by statistically uneven surfaces. This work synthesizes the optimal algorithm and structure for analyzing the parameters of statistically-temporal surfaces based on spatio-temporal processing of optical speckle interference signals and images using modern methods of optimal synthesis of radio engineering and coherent optoelectronic systems. In this work, an algorithm for processing optical signals scattered by statistically uneven surfaces is synthesized and investigated for problems of optimal estimation of parameters and statistical characteristics of statistically uneven surfaces. A block diagram of the optical contactless device for evaluating the parameters of statistically uneven surfaces is proposed. The limiting errors of estimation parameters of statistically uneven surfaces and the optimal installation angles of the emitters and the optical receiver are investigated. Equations are obtained for estimating the root-mean-square height of the ridges and the correlation radius of small-scale statistically uneven surfaces in the approximation of small perturbations. The proposed method for evaluating the parameters of statistically uneven surfaces allows to increase the accuracy of measurements, to conduct a non-contact assessment of the parameters - even statistically uneven surfaces that have geometric surface irregularities or located in hard-to-reach places, for example, grooves, holes, as well as products of cylindrical, spherical and other shapes.

A Bayesian framework for deriving sector-based methane emissions from top-down fluxes

Atmospheric methane observations are used to test methane emission inventories as the sum of emissions should correspond to observed methane concentrations. Typically, concentrations are inversely projected to a net flux through an atmospheric chemistry-transport model. Current methods to partition net fluxes to underlying sector-based emissions often scale fluxes based on the relative weight of sectors in a prior inventory. However, this approach imposes correlation between emission sectors which may not exist. Here we present a Bayesian optimal estimation method that projects inverse methane fluxes directly to emission sectors while accounting uncertainty structure and spatial resolution of prior fluxes and emissions. We apply this method to satellite-derived fluxes over the U.S. and at higher resolution over the Permian Basin to demonstrate that we can characterize a sector-based emission budget. This approach provides more robust comparisons between different top-down estimates, critical for assessing the efficacy of policies intended to reduce emissions.