RAS Techniques and Instruments最新文献_第5页

Morphological Classification of Radio Galaxies with wGAN-supported Augmentation 基于wgan增强的射电星系形态分类

RAS Techniques and Instruments Pub Date : 2022-12-16 DOI: 10.1093/rasti/rzad016

L. Rustige, J. Kummer, F. Griese, K. Borras, Marcus Brüggen, P. Connor, F. Gaede, G. Kasieczka, Tobias Knopp Peter Schleper

{"title":"Morphological Classification of Radio Galaxies with wGAN-supported Augmentation","authors":"L. Rustige, J. Kummer, F. Griese, K. Borras, Marcus Brüggen, P. Connor, F. Gaede, G. Kasieczka, Tobias Knopp Peter Schleper","doi":"10.1093/rasti/rzad016","DOIUrl":"https://doi.org/10.1093/rasti/rzad016","url":null,"abstract":"\u0000 Machine learning techniques that perform morphological classification of astronomical sources often suffer from a scarcity of labelled training data. Here, we focus on the case of supervised deep learning models for the morphological classification of radio galaxies, which is particularly topical for the forthcoming large radio surveys. We demonstrate the use of generative models, specifically Wasserstein Generative Adversarial Networks (wGANs), to generate data for different classes of radio galaxies. Further, we study the impact of augmenting the training data with images from our wGAN on three different classification architectures. We find that this technique makes it possible to improve models for the morphological classification of radio galaxies. A simple Fully Connected Neural Network (FCN) benefits most from including generated images into the training set, with a considerable improvement of its classification accuracy. In addition, we find it is more difficult to improve complex classifiers. The classification performance of a Convolutional Neural Network (CNN) can be improved slightly. However, this is not the case for a Vision Transformer (ViT).","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"41 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121580267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

A new system to measure the gradient vector of the magnetic field on unmanned aerial vehicles (UAV) - data processing and field experiment 一种测量无人机磁场梯度矢量的新系统——数据处理与现场实验

RAS Techniques and Instruments Pub Date : 2022-11-22 DOI: 10.1093/rasti/rzac008

Christian Kulüke, C. Virgil, J. Stoll, A. Hördt

{"title":"A new system to measure the gradient vector of the magnetic field on unmanned aerial vehicles (UAV) - data processing and field experiment","authors":"Christian Kulüke, C. Virgil, J. Stoll, A. Hördt","doi":"10.1093/rasti/rzac008","DOIUrl":"https://doi.org/10.1093/rasti/rzac008","url":null,"abstract":"\u0000 We present a novel airborne magnetometer system deployed on an unmanned aerial vehicle (UAV) that is capable of measuring the horizontal gradient of the three components of the magnetic field. The system consists of two three-component fluxgate magnetometers (FGM) that are mounted on a transverse horizontal boom. The sensor attitude is determined with a low-cost inertial measurement unit. The estimation of the magnetic field components as well as its gradient is extremely sensitive to sensor movement and sensor rotation and requires sophisticated data processing and corrections. Here, we present four specific calibration and correction procedures we consider essential to achieve sufficient accuracy. First, we present a new in-flight calibration method for a FGM gradiometer. Second, we introduce a procedure that corrects for rotation-induced noise in the FGMs that has not been described previously in the literature. In a third step, we correct for mechanical vibrations, which induce high frequency noise in the data. Finally, the gradient of each component is mathematically rotated into the geographical coordinate system. The performance of the system is evaluated on a test site where several metal objects of known magnetisation were placed on the ground surface. For the first time, we show the gradients of magnetic field components measured on a UAV. The gradients agree with the results of a forward simulation within a few nT m−1. The accuracy will be sufficient for many practical applications, such as geological mapping, ore exploration, and the search for metallic bodies.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125377039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A millimetre-wave superconducting hyper-spectral device 毫米波超导超光谱装置

RAS Techniques and Instruments Pub Date : 2022-11-09 DOI: 10.1093/rasti/rzad038

U. Chowdhury, F. Levy-Bertrand, M. Calvo, J. Goupy, A. Monfardini

{"title":"A millimetre-wave superconducting hyper-spectral device","authors":"U. Chowdhury, F. Levy-Bertrand, M. Calvo, J. Goupy, A. Monfardini","doi":"10.1093/rasti/rzad038","DOIUrl":"https://doi.org/10.1093/rasti/rzad038","url":null,"abstract":"\u0000 Millimetre-wave observations represent an important tool for Cosmology studies. The Line Intensity Mapping (LIM) technique has been proposed to map in three dimensions the specific intensity due to line (e.g. [C ii], CO) emission, for example from the primordial galaxies, as a function of redshift. Hyper-spectral integrated devices have the potential to replace the current Fourier transform, or the planned Fabry-Perot-based instruments operating at millimetre and sub-millimetre wavelengths. The aim is to perform hyper-spectral mapping, with a spectral resolution R = λ/Δλ = 100–1000, over large, i.e. thousands of beams, instantaneous patches of the Sky. The innovative integrated device that we have developed allows avoiding moving parts, complicated and/or dispersive optics or tunable filters to be operated at cryogenic temperatures. The prototype hyper-spectral focal plane is sensitive in the 75-90 GHz range and contains nineteen horns for sixteen spectral-imaging channels, each selecting a frequency band of about 0.1 GHz. For each channel a conical horn antenna, coupled to a planar superconducting resonant absorber made of thin aluminium, collects the radiation. A capacitively coupled titanium-aluminium bilayer Lumped Element Kinetic Inductance Detector (LEKID) is then in charge of dissipating and sensing the super-current established in the resonant absorber. The prototype is fabricated with only two photo-lithography steps over a commercial mono-crystalline sapphire substrate. It exhibits a spectral resolution R = λ/Δλ ≈ 800. The optical noise equivalent power of the best channels is in the observational relevant $4cdot 10^{-17} W/sqrt{Hz}$ range. The average sensitivity of all the channels is around $1cdot 10^{-16} W/sqrt{Hz}$. The device, as expected from 3-D simulations, is polarisation-sensitive, paving the way to spectro-polarimetry measurements over very large instantaneous field-of-views.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130228996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The next generation Birmingham Solar Oscillations Network (BiSON) spectrophotometer: a new miniaturised instrument for helioseismology 下一代伯明翰太阳振荡网络(BiSON)分光光度计:一种新的小型日震学仪器

RAS Techniques and Instruments Pub Date : 2022-10-20 DOI: 10.1093/rasti/rzac007

S. Hale, W. Chaplin, G. Davies, Y. Elsworth, R. Howe

引用次数: 2

SARABANDE: 3/4 Point Correlation Functions with Fast Fourier Transforms 快速傅里叶变换的3/4点相关函数

RAS Techniques and Instruments Pub Date : 2022-10-18 DOI: 10.1093/rasti/rzad003

J. Sunseri, Z. Slepian, S. Portillo, Jiamin Hou, Sule Kahraman, D. Finkbeiner

引用次数: 3

The entropy of galaxy spectra: How much information is encoded? 星系光谱的熵:编码了多少信息?

RAS Techniques and Instruments Pub Date : 2022-08-10 DOI: 10.1093/rasti/rzad004

I. Ferreras, O. Lahav, R. Somerville, J. Silk

{"title":"The entropy of galaxy spectra: How much information is encoded?","authors":"I. Ferreras, O. Lahav, R. Somerville, J. Silk","doi":"10.1093/rasti/rzad004","DOIUrl":"https://doi.org/10.1093/rasti/rzad004","url":null,"abstract":"\u0000 The inverse problem of extracting the stellar population content of galaxy spectra is analysed here from a basic standpoint based on information theory. By interpreting spectra as probability distribution functions, we find that galaxy spectra have high entropy, thus leading to a rather low effective information content. The highest variation in entropy is unsurprisingly found in regions that have been well studied for decades with the conventional approach. We target a set of six spectral regions that show the highest variation in entropy – the 4000 Å break being the most informative one. As a test case with real data, we measure the entropy of a set of high quality spectra from the Sloan Digital Sky Survey, and contrast entropy-based results with the traditional method based on line strengths. The data are classified into star-forming (SF), quiescent (Q) and AGN galaxies, and show – independently of any physical model – that AGN spectra can be interpreted as a transition between SF and Q galaxies, with SF galaxies featuring a more diverse variation in entropy. The high level of entanglement complicates the determination of population parameters in a robust, unbiased way, and affect traditional methods that compare models with observations, as well as machine learning (especially deep learning) algorithms that rely on the statistical properties of the data to assess the variations among spectra. Entropy provides a new avenue to improve population synthesis models so that they give a more faithful representation of real galaxy spectra.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131355588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Simple semi-classical model of pressure-broadened infrared/microwave linewidths in the temperature range 200–3000 K 200-3000 K温度范围内压力加宽红外/微波线宽的简单半经典模型

RAS Techniques and Instruments Pub Date : 2022-07-26 DOI: 10.1093/rasti/rzac004

J. Buldyreva, S. Yurchenko, J. Tennyson

引用次数: 0

ESA-Ariel Data Challenge NeurIPS 2022: Introduction to exo-atmospheric studies and presentation of the Atmospheric Big Challenge (ABC) Database ESA-Ariel数据挑战NeurIPS 2022:介绍大气外研究和大气大挑战(ABC)数据库的介绍

RAS Techniques and Instruments Pub Date : 2022-06-29 DOI: 10.1093/rasti/rzad001

Q. Changeat, K. H. Yip

{"title":"ESA-Ariel Data Challenge NeurIPS 2022: Introduction to exo-atmospheric studies and presentation of the Atmospheric Big Challenge (ABC) Database","authors":"Q. Changeat, K. H. Yip","doi":"10.1093/rasti/rzad001","DOIUrl":"https://doi.org/10.1093/rasti/rzad001","url":null,"abstract":"\u0000 This is an exciting era for exo-planetary exploration. The recently launched JWST, and other upcoming space missions such as Ariel, Twinkle and ELTs are set to bring fresh insights to the convoluted processes of planetary formation and evolution and its connections to atmospheric compositions. However, with new opportunities come new challenges. The field of exoplanet atmospheres is already struggling with the incoming volume and quality of data, and machine learning (ML) techniques lands itself as a promising alternative. Developing techniques of this kind is an inter-disciplinary task, one that requires domain knowledge of the field, access to relevant tools and expert insights on the capability and limitations of current ML models. These stringent requirements have so far limited the developments of ML in the field to a few isolated initiatives. In this paper, We present the Atmospheric Big Challenge Database (ABC Database), a carefully designed, organised and publicly available database dedicated to the study of the inverse problem in the context of exoplanetary studies. We have generated 105,887 forward models and 26,109 complementary posterior distributions generated with Nested Sampling algorithm. Alongside with the database, this paper provides a jargon-free introduction to non-field experts interested to dive into the intricacy of atmospheric studies. This database forms the basis for a multitude of research directions, including, but not limited to, developing rapid inference techniques, benchmarking model performance and mitigating data drifts. A successful application of this database is demonstrated in the NeurIPS Ariel ML Data Challenge 2022.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123739303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

WDPhotTools – a white dwarf photometric toolkit in Python wdphototools -一个用Python编写的白矮星光度测量工具包

RAS Techniques and Instruments Pub Date : 2022-04-01 DOI: 10.5281/zenodo.6595029

M. Lam, Kee Wang Yuen, W. Li, M. Green

引用次数: 1

RAS techniques and instruments RAS技术和仪器

RAS Techniques and Instruments Pub Date : 2022-04-01 DOI: 10.1093/rasti/rzac002

J. Tennyson, A. Scaife

引用次数: 2