8,286 research outputs found
Enhancing Jc(B,theta) in YBa2Cu3O7-delta via nano-engineering of pinning structures
No full textCritical current density (Jc) has been identified as one of the most critical parameters for the practical application of high temperature superconductors such as YBa2Cu3O7-δ (YBCO). Unfortunately, the Jc of optimized un-doped YBCO films barely satisfies the criteria for these applications. High J¬c can be achieved by introducing strong artificial pinning centers in YBCO which can inhibit flux motion and prevent dissipation. However, insertion of strong pins has been observed to strain and poison the YBCO lattice resulting in unnecessary degradation of Tc and low field Jc. In this work, two types of strong pinning centers with negligible effect on the Tc and low field Jc were incorporated in YBCO films via strain engineering on the nanoscale. The nanotube pores were generated by depositing YBCO films on vicinal SrTiO3 (STO) substrates. A close correlation between Jc and the magnetic pinning potential Up of the nanotube pores has been demonstrated below the accommodation field, suggesting that nanotube pores are strong pins on the magnetic vortices. Splayed BaZrO3 nanorords (BZO-NRs) were generated in YBCO film by depositing 2 vol.% BZO-doped YBCO on vicinal STO substrates. The interplay between the lattice strain caused by the large lattice mismatch between YBCO and BZO and the anisotropic strain due to vicinal growth resulted in the dispersed orientation of BZO-NRs. The splayed BZO-NRs led to an enhanced Jc in the entire range of the magnetic field orientation up to 5 T as compared to the non-splayed case of YBCO/BZO-NRs films
A Method to Measure Rotary Speed and Torque Using JC Sensors
No full textA method for rotary speed and torque measuring using JC sensors was introduced in the
paper. The approximate sine signals output by JC sensors are transformed into rectangular signals by
the transform circuit. The checking circuit consists of an 8031 singlechip, it determines the rotary
speed by measuring the frequency of the rectangular signals, and determines torque by measuring
their pulse width.</jats:p
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
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
Preparação e caracterização do supercondutor MgB2
No full textMestrado em Ciência e Engenharia de MateriaisAmostras supercondutoras de MgB2 foram produzidas seguindo os métodos ex
situ e in situ e posteriormente caracterizadas. As amostras ex situ foram
obtidas recorrendo a sinterizações a 950ºC numa prensa isostática a quente
(HIP) sob pressões de 30, 50 e 190MPa. Nestas condições obtiveram-se
valores de densidade até 98% da densidade teórica do material. Foram usadas
técnicas de XRD, SEM, TEM e EDS para caracterizar as amostras que
revelaram uma melhoria do controlo sobre a formação de fases secundárias.
Recorrendo a uma técnica de encapsulamento em vidro as quantidades finais
de MgO foram limitadas a ~10% (em massa) e a formação de MgB4 foi
impedida. As amostras in situ foram obtidas através do encapsulamento de
misturas de pós de Mg e B nas proporções molares de 1:2, 1.2:2 e 1.5:2 e
posterior sinterização em vácuo num forno de grafite. Deste processo
resultaram amostras porosas e com fraca resistência mecânica. Técnicas de
SEM, EDS e XRD revelaram grandes quantidades finais de MgO enquanto que
a formação de MgB4 foi evitada. As amostras ex situ são supercondutoras com
valores de Tc~37K e respectivas larguras de transição na ordem dos 0.5 K.
Para além destes resultados, as medidas eléctricas e magnéticas permitiram
também determinar os valores de densidade de corrente crítica, Jc, do
material. Contrariamente ao Tc, o Jc parece ser sensível às condições de
processamento e foram obtidos valores que variam entre 0.37 e 3.89 x106
A/cm2 a 10K.
ABSTRACT: Superconducting bulk samples of MgB2 were produced, using ex situ and in
situ processing routes, and characterized. Ex situ samples were obtained by
hot isostatic pressing (HIP) under pressures up to ~200MPa at 950ºC. In these
conditions, full densification of samples was obtained (~98% of theoretical
density). SEM, TEM, EDS and XRD analysis on final dense bodies were used
to evaluate samples. These show increasing improvement in controling the
amounts of secondary phases. MgO was limited down to ~10% wt. and
complete prevention of formation of MgB4 by using simple glass encapsulation
techniques and addition of Mg(s) to the capsule. In situ samples were obtained
by encapsulating and sintering a mixture of Mg and B powders with Mg:B molar
ratios of 1:2, 1.2:2 and 1.5:2 under vacuum in a graphite furnace. This process
resulted in porous samples with poor mechanical resistance. SEM, EDS and
XRD analysis have shown large amounts of MgO while MgB4 formation was
successfully avoided. Ex situ samples display superconducting properties
(Tc~37 K), including narrow critical transition in electrical properties (ΔTc~0.5 K).
Magnetic and electric measurements were performed allowing the
determination of critical current density, Jc, and critical transition temperature,
Tc, of the material. Contrary to Tc, Jc is quite sensitive to the processing
conditions and values from 0.37 and 3.89x106 A/cm2 are obtained at 10K
Regulation of vertebrate myotome development by the p38 MAP kinase-MEF2 signaling pathway.
No full textBiochemical and cell culture studies have characterized the myocyte enhancer factor 2 (MEF2) transcriptional regulatory proteins as obligatory partners for the myogenic regulatory factors (MRFs) in the differentiation of myogenic cells in culture. However, the role of MEF2 activation in somitic myogenesis has not been fully characterized. Here, we report a critical interaction between the p38 mitogen-activated protein kinase (p38 MAPK) and MEF2 in the developing somite myotome. We document expression of MEF2A and p38 MAPK proteins in the somite of 9.5 dpc mouse embryos concurrent with Myf 5 protein expression. We also observed that abrogation of p38 MAPK signaling blocks MEF2 activation using a MEF2 transgenic 'sensor' mouse. Inhibition of p38 MAPK signaling concurrently inhibited myogenic differentiation in somite cultures and in embryos in vivo using transplacental injection of a p38 inhibitor (SB203580). Finally, we document that commitment to the myogenic lineage is not appreciably affected by p38 MAPK inhibition since the activation of an early marker of myogenic commitment (Myf 5) occurs normally when p38 MAPK signaling is inhibited. Thus, we present novel evidence indicating a crucial role for p38 MAPK signaling to the MEF2 transcriptional regulators during early mammalian somite development and myotome formation
Influence of disorder on the in-field Jc of MgB2 wires using highly active pyrene
No full textIn this work, we report on significantly enhanced critical current density (Jc) in Mg B2 superconductor that was easily obtained by doping with a hydrocarbon, highly active pyrene (C16 H10), and using a sintering temperature as low as ∼600 °C. The processing advantages of the C16 H10 additive include production of a highly active carbon (C) source, an increased level of disorder, and the introduction of small grain size, resulting in enhancement of Jc
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