A visual and full-field method for detecting quench and normal zone propagation in HTS tapes

A fast and effective quench detection method is especially challenging in the development of high-field high-temperature superconducting (HTS) magnets for their safe operations and reliably releasing the stored energy during a quench. The occurrence and propagation of a quench are often accompanied by strong thermal and magneto-mechanical responses within superconducting magnets. Aiming to detect a quench in the whole process and capture the thermoelastic behavior associated with it, a new detection technique with a visual and full-field perception based on the digital image correlation (DIC) method is proposed in the present study. The experiment of a quench triggered thermally by a local spot heater is conducted for a YBCO coated conductor tape in a cryogenic chamber. The evolution and characteristics of the full-field strain in the HTS tape during the processes of a non-quench, a quench occurrence and quench propagation are intuitively presented with experimental observations. For the comparison purpose, the conventional quench detection methods by monitoring temperature and voltage signals during a quench are also utilized experimentally. The results verify the visual and full-field quench detection method which uses a criterion of thermoelastic strain-rate for the quench occurrence and the evolution of strain contours for the normal zone propagating aspect. Additionally, a numerical quench model of coupled thermoelasticity to simulate the experiment is established and solved with the aid of Comsol multiphysics software. The quantitative results are in good agreement with the experimental measurements to prove the reliability and availability of the developed detection method. Since the DIC method is non-contact and insensitivity to intense electromagnetic interferences, it is expected to provide a new technique on quench issues and some basic measurements on strain/stress behaviors in extreme environments of high-field HTS magnets in the future.

TECHNICAL ANALYSIS OF FOOD AND BEVERAGE SECTOR STOCKS IN JII

ABSTRAK Investasi merupakan upaya menanamkan dana untuk dikembangkan dalam jangka waktu yang telah ditentukan untuk mendapatkan keuntungan. Investasi bisa dilakukan melalui sektor rill, maupun non rill. Pada penelitian ini akan membahas investasi sektor non rill terutama di pasar modal yang sudah jelas return dan kemanannya, yang akan berfokus pada saham. JII (Jakata Islmaic Index) adalah 30 saham syariah yang paling liquid di BEI. Terdapat empat saham sektor food and beverage, seperti ICBP, INDF, JPFA, dan UNVR. analisis teknikal menggunakan historis harga dari suatu perusahaan atau saham itu sendiri, yang berasumsi bahwa itu dapat merefleksikan harga dimasa depan, biasanya yang menggunakan analisis teknikal adalah investor jangka pendek, jangka pendek disini adalah mereka para tradder yang aktif berdagang saham. Grafik adalah indikator utama untuk analisis teknikal, terutama grafik candlestick karena grafik ini mampu menampilkan pergerakan harga secara menyeluruh. Resistance adalah keadaan dimana harga sulit bergerak lebih tinggi, sedangkan support adalah kebalikannya yaitu harga sudah sulit untuk lebih rendah, kedua garis batas ini digunakan sebagai pengambil keputusan dalam analisis teknikal. Pendekatan yang biasa dilakukan adalah menggunakan pendekatan fibonacci dan umunya dibantu lagi oleh stochastic oscillator untuk menunjukan posisi closing relatif pada suatu periode. Saham ICBP dilihat dari hasil fibonacci dan indikator stochastic oscillator yang menunjukan saham ICBP mendekati resistance dan stochastic oscillator berada pada titik 70 normal zone tetapi mulai mendekati zona overbought yaitu melewati titik 80. Kata kunci : : Investasi, Analisis Teknikal, Fibonnaci, Support, Resistance, Stochastic Oscillato

Quench Detection and Protection for High-Temperature Superconductor Accelerator Magnets

High-temperature superconductors (HTS) are being increasingly used for magnet applications. One of the known challenges of practical conductors made with high-temperature superconductor materials is a slow normal zone propagation velocity resulting from a large superconducting temperature margin in combination with a higher heat capacity compared to conventional low-temperature superconductors (LTS). As a result, traditional voltage-based quench detection schemes may be ineffective for detecting normal zone formation in superconducting accelerator magnet windings. A developing hot spot may reach high temperatures and destroy the conductor before a practically measurable resistive voltage is detected. The present paper discusses various approaches to mitigating this problem, specifically focusing on recently developed non-voltage techniques for quench detection.