scholarly journals Effect Analysis of the Digital Spectrometer FFT Algorithm on THz Atmospheric Limb Sounder (TALIS) System Sensitivity

2021 ◽  
Vol 13 (15) ◽  
pp. 2921
Author(s):  
Haowen Xu ◽  
Hao Lu ◽  
Zhenzhan Wang ◽  
Wenming He ◽  
Wenyu Wang
Keyword(s):  
Chemical Constituents ◽  
Microwave Radiometer ◽  
Mean Value ◽  
Integration Time ◽  
Science Center ◽  
Effect Analysis ◽  
System Sensitivity ◽  
Full Band ◽  
Digital Spectrometer ◽  
The Ideal

THz Atmospheric Limb Sounder (TALIS) is a microwave radiometer designed by the National Space Science Center of the Chinese Academy of Sciences (NSSC, CAS) for measuring the vertical distribution of temperature and chemical constituents in the middle and upper atmosphere. The digital spectrometer is an important part of TALIS’ back end, which mainly realizes the function of spectral analysis. The radix 16 real-time complex fast Fourier transform (FFT) algorithm used in the digital spectrometer was obtained by improving and combining the parallel processing and complex processing of the FFT algorithm. In this study, the digital spectrometer parameter selection is systematically presented, and the effect of the digital spectrometer FFT algorithm on the TALIS system sensitivity is analyzed based on the TALIS system simulation model we established in the previous stage of this research. The results show that the actual full-band sensitivity obtained after using the FFT algorithm is consistent with the ideal full-band sensitivity of TALIS for different integration time, spectral resolutions, and quantization bits. However, the results of the comparison of the actual sub-band sensitivity after using the FFT algorithm with the ideal sub-band sensitivity show that the deterioration of the sub-band sensitivity will be caused by the FFT algorithm. The mean value of the deterioration ratio was found to be approximately 18%, and the maximum value of the deterioration ratio was approximately 33%.

scholarly journals Simulation of the Spectrum Response for the THz Atmosphere Limb Sounder (TALIS)

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 498
Author(s):  
Yongqiang Duan ◽  
Zhenzhan Wang ◽  
Haowen Xu ◽  
Wenyu Wang
Keyword(s):  
Spectral Response ◽  
Microwave Radiometer ◽  
Chemical Species ◽  
Center Frequency ◽  
Integration Time ◽  
Science Center ◽  
National Space ◽  
Degradation Ratio ◽  
Scientific Goal ◽  
Academy Of Sciences

The THz atmospheric limb sounder (TALIS) is a microwave radiometer developed by the National Space Science Center of the Chinese Academy of Sciences for the detection of atmospheric trace gases. The observation range of the instrument mainly focuses on the middle and upper atmosphere (10–100 km above the earth’s surface). The detection targets include the temperature, pressure, and more than 10 kinds of atmospheric components. Its scientific goal is to improve our comprehension of atmospheric chemical composition and dynamics, and to monitor environmental pollution and sources in the atmosphere. The TALIS instrument is composed of an antenna, superheterodyne radiometers, and digital fast Fourier transform (FFT) spectrometers. By measuring the atmospheric thermal radiance in the wide frequency band with 118, 190, 240, and 643 GHz as the center frequency, the required volume mixing ratio (VMR) of atmospheric chemical species can be obtained. This paper introduces the characteristics of the TALIS instrument, and establishes a simulation model for the TALIS spectrometer. Through a joint simulation with an atmosphere radiative transfer simulator (ARTS), the TALIS instrument performance is evaluated from the aspects of calibration, the imbalance of two sidebands, the spectrum resolution, and quantization. The simulation results show that the two-point calibration can well-restore the radiance spectrum of the scene target and remove the influence of the spectral response function (SRF); the double side band (DSB) receiver with a 2 MHz resolution can meet the sensitivity and spectrum resolution requirements. Finally, the sensitivity errors of different quantization bits are given by the simulation and the results show that at 8-bit, the sensitivity and its degradation ratio are 1.251 K and 1.036 at a 2 MHz spectrum resolution and 100 ms integration time, respectively.

scholarly journals A Comparison of the Mean-Value and Initial-Value Solutions of the Ideal Resonance Problem with an Application in Rigid-Body Mechanics

1974 ◽  
Vol 62 ◽  
pp. 209-209
Author(s):  
A. H. Jupp
Keyword(s):  
Elliptic Functions ◽  
Mean Value ◽  
Resonance Problem ◽  
Ideal Resonance ◽  
Deep Circulation ◽  
Ideal Resonance Problem ◽  
Rigid Body Mechanics ◽  
The Mean ◽  
Mean Elements ◽  
The Ideal

A solution of the ideal resonance problem has already been exhibited (Jupp, 1972) explicitly in terms of the ‘mean’ elements; to second order in the small parameter in the case of libration, and to first order in the case of deep circulation. Both representations possess a singularity when the ‘mean’ modulus of the Jacobi elliptic functions is unity; this corresponds to motions on or close to the separatrix of the phase plane of the dynamical system.

scholarly journals The zero gravity curve and surface and radii for geostationary and geosynchronous satellite orbits

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
L.E. Sjöberg ◽  
E.W. Grafarend ◽  
M.S.S. Joud
Keyword(s):  
Gravitational Force ◽  
Harmonic Coefficient ◽  
Mean Value ◽  
Geostationary Satellite ◽  
Satellite Orbits ◽  
Zero Gravity ◽  
Geosynchronous Satellite ◽  
The Earth ◽  
Special Case ◽  
The Ideal

AbstractA geosynchronous satellite orbits the Earth along a constant longitude. A special case is the geostationary satellite that is located at a constant position above the equator. The ideal position of a geostationary satellite is at the level of zero gravity, i.e. at the geocentric radius where the gravitational force of the Earth equals the centrifugal force. These forces must be compensated for several perturbing forces, in particular for the lunisolar tides. Considering that the gravity field of the Earth varies not only radially but also laterally, this study focuses on the variations of zero gravity not only on the equator (for geostationary satellites) but also for various latitudes. It is found that the radius of a geostationary satellite deviates from its mean value of 42164.2 km only within ±2 m, mainly due to the spherical harmonic coefficient J

Eustathius over de Homerische goden, de plausibiliteit van de Ilias en de deskundigheid van Homerus

Lampas ◽  
2018 ◽  
Vol 51 (1) ◽  
pp. 43-60
Author(s):  
Baukje van den Berg
Keyword(s):  
Twelfth Century ◽  
Target Audience ◽  
Science Center ◽  
National Science ◽  
Composition Process ◽  
Voor Zijn ◽  
The Ideal

Summary This article Dit artikel is geschreven als onderdeel van een project gefinancierd door het National Science Center, Polen (UMO-2013/10/E/HS2/00170). Ik dank Niels Koopman voor zijn commentaar. explores the role of the gods in the Iliad as analysed by Eustathius of Thessaloniki in his Commentary on the Iliad. Eustathius aims to identify the principles and techniques that underlie Homer’s successful composition and to reconstruct, as it were, Homer’s composition process. In this way, he intends to familiarise his target audience, twelfth-century authors of rhetorical prose, with Homer’s admirable methods so that they can imitate them in their own writings. Eustathius interprets the gods as devices in the hands of the poet to steer his composition in the desired direction, to imbue it with rhetorical plausibility, and to foreground his skilfulness. Homer uses the gods in four ways: 1) by means of divine interventions, Homer maintains plausibility whenever he takes risks for the sake of rhetorical virtuosity; 2) the poet employs divine plans to motivate the course of events; 3) as allegories of the poet’s intellectual capacities the gods reveal authorial deliberations about the course of the Iliad; 4) the composition of the Iliad is partly determined by the meaning of the gods in terms of natural and ethical allegory. Eustathius thus presents Homer as a self-conscious author and shapes him, we may assume, in the image of the ideal Byzantine author, or perhaps that of himself.

scholarly journals Preliminary Evaluation of the Error Budgets in the TALIS Measurements and Their Impact on the Retrievals

2020 ◽  
Vol 12 (3) ◽  
pp. 468 ◽  
Author(s):  
Wenyu Wang ◽  
Zhenzhan Wang ◽  
Yongqiang Duan
Keyword(s):  
Measurement Errors ◽  
Chemical Constituents ◽  
A Priori ◽  
Local Oscillator ◽  
Antenna Pattern ◽  
Preliminary Evaluation ◽  
Good Precision ◽  
Science Center ◽  
The Impact ◽  
Hot Target

The THz Atmospheric Limb Sounder (TALIS) is a Chinese sub-millimeter limb sounder being designed by National Space Science Center of the Chinese Academy of Sciences to measure the temperature and chemical constituents vertically in the middle and upper atmosphere, with good precision and vertical resolution. This paper presents a simulation study that assesses the measurement errors and their impacts on the retrievals. Three error sources, including instrument uncertainties, calibration errors and a priori errors, are considered. The sideband weight uncertainty, the local oscillator, the pointing angle offsets and the measurement noise (NEDT), are considered as instrument uncertainties. Calibration errors consist of the hot target offset, the nonlinearity residual of the two-point calibration, use of the Rayleigh–Jeans (R–J) approximation and the choice of the antenna pattern. A priori profile errors of temperature, pressure and species are also considered. The results suggest that the antenna pattern mainly affects the retrievals in the troposphere. The NEDT is a major error source affecting all of the retrievals. The R–J approximation has a great impact upon the retrievals at 643 GHz, and should not be used. The local oscillator offset leads to an obvious error above 50 km. The effect of nonlinearity residuals cannot be neglected above 70 km. The impact of the sideband weight uncertainty and the hot target offset are relatively small. The pointing and the a priori errors can be neglected in most observation regions.

scholarly journals WOOD AND CHARCOAL PRODUCTION IN THE KILN-FURNACE SYSTEM: HOW DO THE COSTS AND REVENUES VARIATION AFFECT ECONOMIC FEASIBILITY?

2021 ◽  
Vol 45 ◽  
Author(s):  
Bruno Leão Said Schettini ◽  
Laércio Antônio Gonçalves Jacovine ◽  
Carlos Moreira Miquelino Eleto Torres ◽  
Angélica de Cássia Oliveira Carneiro ◽  
Paulo Henrique Villanova ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Net Present Value ◽  
Mean Value ◽  
Economic Feasibility ◽  
Economic Viability ◽  
Cost Ratio ◽  
Charcoal Production ◽  
New Production ◽  
System Sensitivity ◽  
Benefit Cost Ratio

ABSTRACT Traditional methods of economic evaluation of wood and charcoal production projects are based on indicators analysis, however, they are subject to market variations and uncertainties. The study was carried out in the city of Lamim, Minas Gerais State, to evaluate the economic viability of wood and charcoal production using the kiln-furnace system, due to the need to know the economic viability of this new production system. Sensitivity analysis using the Monte Carlo technique was performed on costs and revenues. The wood and charcoal production cash flow was elaborated and the following criteria were used in the economic analysis: Net Present Value (NPV), Benefit-Cost Ratio (BCR), Equivalent Periodic Value (EPV), and Internal Return Rate (IRR). The wood and charcoal production sensitivity analysis was carried out using the software @RISK, according to the VPE parameter, which allows comparing projects with different durations. Wood production was economically viable, with NPV of $40.26 ha-1 and EPV of $ 16.80 ha-1, with an average production cost of $13.51 m3 wood-1. The EPV mean value found in the sensitivity analysis was $18.33 ha-1. The charcoal production was economically viable, with NPV of $4.43 mdc charcoal-1 and EPV of $3.52 mdc charcoal-1. The EPV mean value found in the sensitivity analysis was $9.80 mdc charcoal-1. It was possible to conclude that the wood and charcoal production are economically viable in the region.

scholarly journals Mining Low-Variance Biclusters to Discover Coregulation Modules in Sequencing Datasets

2012 ◽  
Vol 20 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Zhen Hu ◽  
Raj Bhatnagar
Keyword(s):  
Transcription Factors ◽  
High Throughput ◽  
Upper Bound ◽  
High Throughput Sequencing ◽  
Subspace Clustering ◽  
Mean Value ◽  
Variance Bounds ◽  
Clustering Techniques ◽  
Gene Sets ◽  
The Ideal

High-throughput sequencing (CHIP-Seq) data exhibit binding events with possible binding locations and their strengths, followed by interpretation of the locations of peaks. Recent methods tend to summarize all CHIP-Seq peaks detected within a limited up and down region of each gene into one real-valued score in order to quantify the probability of regulation in a region. Applying subspace clustering techniques on these scores can help discover important knowledge such as the potential co-regulation or co-factor mechanisms. The ideal biclusters generated would contain subsets of genes and transcription factors (TF) such that the cell-values in biclusters are distributed around a mean value with very low variance. Such biclusters would indicate TF sets regulating gene sets with very similar probability values. However, most existing biclustering algorithms neither enforce low variance as the desired property of a bicluster, nor use variance as a guiding metric while searching for the desirable biclusters. In this paper we present an algorithm that searches a space of all overlapping biclusters organized in a lattice, and uses an upper bound on variance values of biclusters as the guiding metric. We show the algorithm to be an efficient and effective method for discovering the possibly overlapping biclusters under pre-defined variance bounds. We present in this paper our algorithm, its results with synthetic, CHIP-Seq and motif datasets, and compare them with the results obtained by other algorithms to demonstrate the power and effectiveness of our algorithm.

scholarly journals Review of tropospheric temperature, absolute humidity and integrated water vapour from the HAMSTRAD radiometer installed at Dome C, Antarctica, 2009–14

2015 ◽  
Vol 27 (6) ◽  
pp. 598-616 ◽  
Author(s):  
P. Ricaud ◽  
P. Grigioni ◽  
R. Zbinden ◽  
J.-L. Attié ◽  
L. Genoni ◽  
...  
Keyword(s):  
Water Vapour ◽  
Microwave Radiometer ◽  
Correlation Coefficients ◽  
Absolute Humidity ◽  
Time Correlation ◽  
Integration Time ◽  
Tropospheric Temperature ◽  
Extensive Evaluation ◽  
Vertical Profiling ◽  
Integrated Water Vapour

AbstractThe HAMSTRAD (H2O Antarctica Microwave Stratospheric and Tropospheric Radiometers) instrument is a microwave radiometer installed at Dome C (Antarctica, 75°06'S, 123°21'E, 3233 m a.m.s.l.) dedicated to the tropospheric measurements of temperature, absolute humidity and integrated water vapour (IWV). The aim of the present paper is to review the entire HAMSTRAD dataset from 2009 to 2014 with a 7-minute integration time from 0 to 10 km by comparison with coincident radiosondes launched at 12h00 UTC at Dome C. Based upon an extensive evaluation of biases and time correlation coefficients (r), we can state: i) IWV is of excellent quality (r>0.98) and can be used without retrieving significant bias, ii) temperature is suitable for scientific analyses over 0–10 km with a high time correlation with radiosondes (r>0.80) and iii) absolute humidity is suitable for scientific analyses over 0–4 km with a moderate time correlation against radiosondes (r>0.70). The vertical distribution of temperature (0–10 km) and absolute humidity (0–4 km) is subject to biases that need to be removed if the analyses require the use of vertical profiling. The HAMSTRAD dataset is provided in open access to the scientific community.

scholarly journals Variability of Green Time to Discharge a Specified Number of Queued Vehicles at a Signalized Intersection

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yi Zhao ◽  
Yongfeng Ma ◽  
Jian Lu ◽  
Yankai Zong ◽  
Qian Wan
Keyword(s):  
Statistical Data ◽  
Mean Value ◽  
Signalized Intersections ◽  
Signal Timing ◽  
Passing Rate ◽  
Start Up ◽  
Headway Distribution ◽  
The Mean ◽  
New Perspective ◽  
The Ideal

The aim of this paper is to study the headway distribution of queued vehicles (less than 16 vehicles) at signalized intersections. Existing studies usually take the average statistics of headway at any queuing place. When different percentile points of statistical data are assigned to headway, the passing rate (the rate of all queued vehicles passing the stop line) under the ideal signal timing scheme varies. When selecting the mean value, the passing rate of a queue of fewer than 16 vehicles is no more than 65%. When selecting 75% as the percentile, the passing rate is up to 94%. The queue length also decides the assigned percentile of headway to ensure the passing rate reaches a certain level. The value assignation of headway directly affects lane capacity and start-up loss time. This paper provides a new perspective on parameter calibration and will make the signal timing algorithm method more effective.

scholarly journals Calibration of a Polarimetric Microwave Radiometer Using a Double Directional Coupler

2021 ◽  
Vol 13 (11) ◽  
pp. 2109
Author(s):  
Luisa de la Fuente ◽  
Beatriz Aja ◽  
Enrique Villa ◽  
Eduardo Artal
Keyword(s):  
Directional Coupler ◽  
Microwave Radiometer ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Stokes Parameters ◽  
Microwave Background ◽  
Feed System ◽  
Polarimetric Microwave Radiometer ◽  
Full Band ◽  
Linearly Polarized

This paper presents a built-in calibration procedure of a 10-to-20 GHz polarimeter aimed at measuring the I, Q, U Stokes parameters of cosmic microwave background (CMB) radiation. A full-band square waveguide double directional coupler, mounted in the antenna-feed system, is used to inject differently polarized reference waves. A brief description of the polarimetric microwave radiometer and the system calibration injector is also reported. A fully polarimetric calibration is also possible using the designed double directional coupler, although the presented calibration method in this paper is proposed to obtain three of the four Stokes parameters with the introduced microwave receiver, since V parameter is expected to be zero for the CMB radiation. Experimental results are presented for linearly polarized input waves in order to validate the built-in calibration system.

Sign in / Sign up

Export Citation Format

Share Document