Teknik Synthetic Aperture Radar (SAR) interferometri merupakan salah satu metode yang digunakan untuk pengamatan deformasi permukaan. Teknik SAR interferometri memiliki kelebihan yaitu dapat mengukur ...besarnya deformasi permukaan hingga satuan milimeter. Walaupun teknik SAR Interferometri memiliki kelebihan, teknik SAR interferometri tetap memiliki kekurangan yaitu hanya dapat memberikan informasi deformasi permukaan 1 dimensi (vertikal) saja. Kelemahan tersebut mengakibatkan teknik SAR interferometri sulit digunakan untuk membantu dalam proses interpretasi sumber dan mekanisme deformasi yang terjadi. Penelitian ini bertujuan untuk ekstraksi deformasi permukaan 2.5-D (2.5 Dimensi) akibat gempa bumi Iran 14 November 2021. Data yang digunakan untuk uji algoritma 2.5-D adalah citra SAR Sentinel-1 sebanyak 2 pasang citra. Citra tersebut adalah citra yang diakuisisi pada tanggal 13 November 2021 dan 19 November 2021. Citra SAR Sentinel-1A diolah menggunakan perangkat lunak GMTSAR dengan arah orbit ascending dan descending. Citra SAR Sentinel-1A yang sudah diolah menggunakan GMTSAR menghasilkan pergeseran permukaan tanah terhadap arah pandang satelit (Line of Sight). Hasil dari penelitian ini diketahui bahwa komponen horizontal terjadi pergeseran sebesar 200 mm ke arah barat. Pergeseran komponen vertikal mengalami kenaikan permukaan tanah sebesar 541 mm pada area utara dan penurunan permukaan tanah maksimal sebesar 231 mm pada area selatan. Berdasarkan hasil tersebut, diketahui bahwa nilai pergeseran komponen vertikal lebih besar daripada komponen horizontal. Hal tersebut menunjukkan bahwa gempa bumi Iran 14 November 2021 diindikasikan disebabkan oleh aktivitas sesar dengan mekanisme sesar naik (thrust fault).
Bu çalışmada çok katlı bina, köprü vb. yapıların anlık sağlık durumlarının takibinde kullanılmak amacıyla uzaktan algılama ve temassız ölçüm tekniklerine dayalı, programlanabilir robotik bir tarayıcı ...sistem geliştirilmesi amaçlanmaktadır. Önerilen sistem, ölçüm tekniği olarak lazer Doppler interferometri kullanılacağı için test edilen yapılar üzerine herhangi bir sensör yerleştirilmesine ihtiyaç duyulmadan her türlü yapıya kolaylıkla uygulanabilir. Yüksek hassasiyet ve çözünürlükte ölçüm alınabilmesi amacıyla, yüksek örnekleme frekansına sahip bir lazer Doppler titreşimölçer, yatay ve düşey eksenlerde bağımsız hareket edebilen motorize bir platform üzerine yerleştirilmiştir. Platforma eklenen kameralı görüntüleme sistemleri, geliştirilen kontrol algoritmaları ve arayüz yardımıyla, kullanıcının test ve ölçümler ile ilgili çeşitli parametreleri kişisel bilgisayarı üzerinden kontrol edebileceği bütünleşik bir yapı oluşturulmuştur. Geliştirilen tarayıcı sistem laboratuvarda kurulan küçük ölçekli çok katlı bina modelleri üzerinde test edilerek yapıların dinamik özelliklerinin yüksek doğruluk ve çözünürlükte çıkarılabildiği gösterilmiştir. Önerilen sistem birden fazla yapının düzenli bir şekilde taranmasına imkan sağlayacak şekilde programlanabilmektedir. Elde edilen titreşim verisinin analizi sonucunda yapının doğal frekanslarının, sönümleme oranlarının ve mod şekillerinin hızlı ve etkin bir şekilde hesaplanabildiği görülmüştür.
ABSTRAK Teknologi Radar, terus berkembang dengan pesat hingga saat ini. Peluncuran satelit ERS-1 pada tahun 1991 dilanjutkan dengan satelit ERS-2 pada tahun 1995 dan diteruskan dengan misi E1VYISAT ...pada akhir tahun 2001 dengan mengandalkan sensor aktifyang disebut ASAR (Advanced Synthetic Aperture Radar), peluncuran SRTM (Shuttle Radar Topographic Mission) serta pengembangan sistim sensor aktif dengan pesawat terbang, menunjukkan betapa pentingnya sistim yang sangat menjanjikan ini untuk dimanfaatkan dan dikembangkan untuk misi-misi yang erat dengan masalah pengadaan data spasial. Sekitar 15% hiungga 20% wilayah Indonesia hampir sepanjang tahun tertutup awan, dan ini menyebabkan belum terselesaikannya pembuatan pets rupabumi untuk wilayah-wilayah tersebut. Tulisan berikut ini menjelaskan secara umum bagaimana kitct mendapatkan model permukaan bumi khususnya dengan menggunakan teknologi Radar Interferometri, yang sering dikenal dengan INSAR
When the First Edition was published, interferometry was regarded as a rather esoteric method of making measurements, largely confined to the laboratory. Today, however, besides its use in several ...fields of research, it has applications in fields as diverse as measurement of length and velocity, sensors for rotation, acceleration, vibration and electrical and magnetic fields, as well as in microscopy and nanotechnology.
Most topics are discussed first at a level accessible to anyone with a basic knowledge of physical optics, then a more detailed treatment of the topic is undertaken, and finally each topic is supplemented by a reference list of more than 1000 selected original publications in total. Extensive coverage is given of the applications of interferometry, such as measurements of length, optical testing, interference microscopy, interference spectroscopy, Fourier-transform spectroscopy, interferometric sensors, nonlinear interferometers, stellar interferometry, and studies of space-time and gravitation.
Particle Image Velocimetry Raffel, Markus; Kompenhans, Jürgen; Wereley, Steve T ...
2007, 2007-09-14, 20070401
eBook
This practical guide to PIV provides in a condensed form most of the information relevant for the planning, performance and understanding of experiments employing the PIV technique. In its second ...edition, the authors updated the chapters on the principles and included information on microscopic, high-speed and three component measurements as well as a description of advanced evaluation techniques. Steve Wereley with his knowledge completed the group of authors of the first edition and his participation as an author was the key for that update. But also the drastic increase in the range of possible applications has been taken into account as the chapter describing representative applications of the PIV technique has been expanded considerably. The resulting book is mainly intended for engineers, scientists and students, who already have some basic knowledge of fluid mechanics and non-intrusive optical measurement techniques. For many researchers and engineers planning to utilize PIV for their special industrial or scientific applications, PIV is just an attractive tool with unique features which may help them to gain new insights in problems of fluid mechanics. These people are usually not interested in becoming specialists in this field before starting their investigations. On the other side some of the basic properties of PIV must be well understood before a correct interpretation of the results is possible.
First VLTI observations of Mira stars Richichi, Andrea; Wittkowski, Markus
Astrophysics and space science,
01/2003, Letnik:
286, Številka:
1-2
Journal Article
Recenzirano
We present first observations of Mira stars obtained at the Very Large Telescope Interferometer (VLTI) at 2 microns, equipped with the VINCI instrument, using different baselines with both the test ...siderostats and the 8.2 m unit telescopes. These observations, collected in the course of the VLTI commissining program, have targeted so far about sixty cool giant stars. In this talk, we list and describe the measurements obtained for 14 Mira stars, many of them representing first-time determinations of the visibility. In particular, we devote special attention to a study of Mira itself, for which very accurate determinations of the visibility at several baseline lenghts and orientations could be obtained. We find that a two-component model is more consistent with the data than a single stellar disc. Further observations are needed for a better understanding of this source. The VLTI will constitute an ideal instrument for such studies in the future. In particular it will permit detailed investigations of southern AGB stars, such as accurate measurements of surface structureparameters (diameters, diameter variations, asymmetries, center-to-limbvariations, special features like hot spots) and of circumstellar envelopes.PUBLICATION ABSTRACT
Massonnet discusses his work using satellite radar interferometry to map geologic faults that have ruptured in earthquakes and to follow the heaving of volcanic mountains as molten rock accumulates ...and ebbs away beneath them. Radar satellites can sense barely perceptible movements of the earth's surface from far away in space.
Im Rahmen dieses Beitrages wird die Weiterentwicklung eines Michelson-Interferometer- Aufbaus 3, 4 zur Messung von Formabweichungen rotierender Messobjekte vorgestellt. Das Interferometer nutzt eine ...sinusförmige Weglängenmodulation im Referenzarm, um Oberflächen rotierender Messobjekte mithilfe einer Zeilenkamera zu erfassen. Der Sensor wurde um zwei zusätzliche interferometrisch messende Punktsensoren erweitert, welche gegenüber einer bekannten Referenzfläche sowohl stochastische als auch systematische Abweichungen der Rotationsbewegung mit einer minimalen Messunsicherheit von unter 1nm erfassen können 7, 8 und so den Einsatz einer kostengünstigen Rotationsachse ermöglichen. Aus den Messdaten der Punktsensoren werden in Echtzeit relative Abstandswerte errechnet. Diese werden gespeichert und nach der Messung zur Korrektur der ebenfalls in Echtzeit ermittelten Höhenwerte des Liniensensors verwendet. Ergebnisse einer Messung unter Verwendung einer Rotationsachse mit starken stochastischen Höhenabweichung werden sowohl mit als auch ohne Korrektur anhand der Punktsensorergebnisse gezeigt. Ein optimiertes mechanisches Design wird vorgestellt, welches durch eine reduzierte Anzahl mechanischer Komponenten die Empfindlichkeit des Sensors gegen äußere Störeinflüsse reduziert.
Um die Grenzen der optischen Messtechnik zu erweitern und feinere Strukturen messbar zu machen, wurden verschiedene Systeme in der aktuellen Forschung publiziert. Es wurde gezeigt, dass im Nahfeld ...aufgebrachte Mikrokugeln die Auflösung eines interferometrischen Messsystems verbessern und Strukturen unterhalb Abbe’s Beugungsgrenze sichtbar machen können. In dieser Studie werden Messergebnisse mit einem hochauflösenden Linnik-Interferometer unterhalb der Auflösungsgrenze gezeigt. Des Weiteren werden simulative Analysen zum Phasenverhalten im Nahfeld der Mikrokugeln vorgestellt, um die theoretische Erklärung des superauflösenden Verhaltens von Mikrokugeln und die bildgebenden Prozesse des Systems zu ermöglichen.
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