3,442 research outputs found
Effect of sample size on magnetic Jc for MgB2 superconductor
No full textA strong effect of sample size on magnetic Jc(H) was observed for bulk MgB2 when Jc is obtained directly from the critical state model. Thus obtained zero-field Jc (Jc0) decreases strongly with the sample size, attaining a constant value for the samples larger than a few millimetres. On the other hand, the irreversibility field (Hirr) defined at Jc = 100 A/cm2 increases with the sample size. The decrease of Jc0 is described in terms of voids in the bulk MgB2 samples and superconducting screening around the cells of superconducting material between these voids (35 micro-m), because of concentration of the current in the narrow bridges connecting the cells. For samples larger than a few millimetres, the value of magnetic Jc is in agreement with the transport Jc and it is restricted by the voids. The critical state model is not suitable for obtaining Jc for small bulk MgB2. The increase of Hirr with the sample size is an artefact of defining Hirr by the value of Jc at which an additional superconducting screening on 1 micro-m scale dominates Delta(m)
Angular Jc measurements at 77 K in-field, on an ISD REBCO coated conductor using a straightforward mechanical scribing technique to reduce tape width
No full textE-J traces have been measured on an inclined substrate deposition coated conductor up to 0.7 T as a function of angle at 77K. A large change in Jc is seen on reversal of the direction of the magnetic field, associated with different surface barriers to flux nucleation. The effect of angular hysteresis and field hysteresis on Jc has been found to be much smaller. Narrow bridges have been successfully fabricated by a simple scribing technique using a diamond-tipped scribe and a template. These bridges have been made from 1.4 mm to 4 mm width on the 12 mm width tape, which decrease Ic linearly with width. Measurements before and after the heat treatment for strain gauge glue curing at 170 °C for 120 min have been made and confirm there is no systematic decrease in Jc
Study of MgB2 ultra-thin films in submicron size bridges
No full textWe discuss a custom built hybrid physical chemical vapour deposition (HPCVD) system for MgB2 ultra-thin film deposition: construction, deposition process development, and optimization. Achieved films on SiC substrates have a critical temperature (Tc) ranging from 35K (10nm thick films) to 41K (40nm thick films). The 20nm thick unpatterned film had a room temperature resistivity of 13μΩ·cm, whereas it becomes 50μΩ·cm in sub-micrometer size bridges with a critical current density Jc (4.2K) up to 1.2×10^8A/cm2. The lower value of resistivity corresponds to the higher of both Tc and Jc. The surface roughness, measured with an atomic force microscope (AFM), is approximately 1.5nm
Perancangan Sistem Informasi Pengelola Barang/Inventaris Di Jc Komp
No full textInventory information system is a system used to enter inventory data into the database, so that there are no errors in input, output data, and reporting based on the desired data. based on surveys and interviews with jc comp personnel, information was obtained that the existing system in the jc comp warehouse section is still manual. therefore, the system that will be created by the author is the result of a replication of the existing system in the jc comp warehouse section. in addition to the process of input and output of goods, this information system is also equipped with features for creating data reports, input and output of goods, and searching for goods data by item name. with the inventory information system is expected to be useful for the warehouse parts jc comp. By implementing this system in the jc comp warehouse, it is hoped that it can reduce errors that may occur. this system is also expected to further speed up the process of input, output, and report generation, which in turn will help the jc comp warehouseSistem Informasi Persediaan Barang adalah sebuah sistem yang digunakan untuk memasukkan data-data persediaan barang ke dalam database, sehinggga tidak terjadi kesalahan dalam input, output data, dan pembuatan laporan berdasarkan data yang diinginkan. Berdasarkan survey dan wawancara dengan bagian personalia Jc Komp, didapatkan informasi bahwa sistem yang ada dibagian gudang Jc Komp masih manual. Oleh karena itu, sistem yang akan dibuat oleh penulis adalah hasil replikasi dari sistem yang telah ada dibagian gudang Jc Comp. Selain proses input dan output barang, pada sistem informasi ini juga dilengkapi fitur pembuatan laporan data, input, dan output barang, dan pencarian data barang berdasarkan nama barang. Dengan adanya Sistem Informasi persediaan barang ini diharapkan dapat bermanfaat bagi bagian gudang Jc Komp. Dengan diterapkannya sistem ini pada bagian gudang Jc Comp, maka diharapkan dapat mengurangi kesalahan-kesalahan yang mungkin terjadi. Sistem ini juga diharapkan dapat lebih mempercepat proses input, output, dan pembuatan laporan yang pada akhirnya dapat membantu bagian gudang Jc Komp
Comparison of Condition Rating Systems for Bridges in Three European Countries
No full textEurope faces many problems connected to ageing infrastructure which was built in the second half of the 20th century. Bridges are one of the crucial elements of these infrastructures. In recent years, European countries have witnessed many failures of bridges across the continent. For example, the collapse of Viadotto Polcevera in Genoa caught the attention of society regarding its tragic consequences. Therefore, engineers must deal with the assessment of existing bridges which is essential for proper decision-making. Condition rating systems for bridges vary from country to country. Consequently, these differences in the methodology can lead to different conclusions related to the future service of assessed structures. For these reasons, this paper briefly describes condition rating systems for road bridges in Italy, Slovakia, and Portugal and defines the differences in the methodology. Subsequently, the obtained conclusions are compared and discussed. The aim of the paper is to encourage standardization in the assessment of bridge health conditions within European countries, highlighting the differences in the current systems adopted by various countries
Amenable L-2-Theoretic Methods and Knot Concordance
No full textWe reveal new structures in the topological knot concordance group. As a key ingredient, we develop obstructions using L-2-theoretic methods for amenable groups in Strebel's class recently introduced by Orr and the author. Concerning (h)-solvable knots, which are defined in terms of certain Whitney towers of height h in bounding 4-manifolds, we show the following: for any n>1, there are (n)-solvable but non-(n. 5)-solvable (and therefore nonslice) knots, which are not detected by prior methods using Cochran-Orr-Teichner L-2-signature obstructions as well as Levine algebraic obstructions and Casson-Gordon invariants.X1197sciescopu
Dynamics of Network Formation Processes in the Co-Author Model
No full textThis article studies the dynamics in the formation processes of a mutual consent network in game theory setting: the Co-Author Model. In this article, a limited observation is applied and analytical results are derived. Then, 2 parameters are varied: the number of individuals in the network and the initial probability of the links in the network in its initial state. A simulation result shows a finding that is consistent with an analytical result for a state of equilibrium while it also shows different possible equilibria.Dynamics, Network, Game Theory, Model,Simulation, Equilibrium, Complexity
High-level polyomavirus JC viruria following long-term steroid therapy
No full textCASE REPORT JC virus is a highly seroprevalent ubiquitous polyomavirus which is acquired at an early age through respiratory or oral route, Thereafter JCV establishes persistent, but mainly asymptomatic, infections in various tissues, including the genitourinary tract and brain Corresponding author Cristina Costa, MD S.C.D.U. Virologia Azienda Ospedaliero-Universitaria San Giovanni Battista di Torino Via Santena, 9 -10126 Torino E-mail: [email protected] increasing with age, with adult prevalence rate often between 15% and 60
Engineering Framework to Utilize Miniaturized Charpy Type SE(B) Specimens to Predict Jc of Full Sized Specimens
No full textAbstractThis paper introduces our experience of using miniature Charpy type SE(B) specimen in obtaining fracture toughness Jc of a material in the ductile to brittle transition temperature (DBTT) region. Width W x thickness B of 2 x 2 mm, 3 x 3 mm and 10 x 10 mm were chosen as miniature specimens and 25 x 25 mm were chosen as full sized specimen. 0.55% carbon steel JIS S55C, whose tensile to yield stress ratio σTS/σYS was equal to 1.8 was chosen as a material to simulate a degraded (embrittled) material in the DBTT region. Focus was placed on whether cleavage fracture could be predicted for these miniaturized specimens. Another focus was placed on whether the Jc of full sized specimen is predictable from the test results of the miniature sized specimens, in case cleavage fracture were observed. The results showed that the modified Ritch-Knott-Rice (RKR) failure criterion (which predicts the onset of cleavage fracture when the crack opening stress measured at 4 times the crack-tip opening displacement exceeds this σ22c) could predict whether cleavage fracture would occur or not. Another finding was that, in case cleavage fracture was observed though, the critical value σ22c in the modified RKR failure criterion was independent of specimen size, and thus, Jc of the full sized specimen is predictable from the miniature specimen test results, though M = (W-a)σYS/Jc was smaller than ASTM E1921 requirement of 30. Here, a and σYS are crack length and yield strength, respectively
Electromigration in the dissipative state of high-temperature superconducting bridges
No full textThe current stimulated atomic diffusion in YBa2Cu3O7 superconducting bridges is investigated. A superconductor to insulator transition can be induced by direct current controlled electromigration process whereas partial recovery of the superconducting state can be achieved by inverting the polarity of the bias. Interestingly, the temperature dependence of the current density Jem(T), above which atomic migration takes place intersects the critical current density Jc(T) at certain temperature T*. Therefore, for T<T* the superconducting dissipative state cannot be accessed without leading to irreversible modifications of the material properties. This phenomenon may also become an important mechanism of local sample deterioration in high critical temperature superconducting films abruptly penetrated by thermomagnetic instabilities
- …
