1,333 research outputs found
[[alternative]]The KT transition of YBCO films
No full text[[abstract]]我們想藉由觀察 YBaCuO 薄膜是否有 KT 變遷的現象,來瞭解薄膜厚度與
維度的關係。故我們製作二塊不同厚度 (240o,120o) 的薄膜,分別量測它
們的電阻率與 V-I 曲線, 並加以分析。其中240o 之 YBCO 薄膜由於厚度
較大,無法表現二維的行為。而120o 的薄膜其 V-I 曲線相關的次方定律
V=I,在 T<76.6K 時, n 滿足二維 Ginzberg- Landau 之線性關係式: n(
T)≒1+const(1-T/Tco)。以此直線與 n=1 之交點定出樣品的 T=79K。而
在n(T)約為5.1時, n 不再隨上述的線性關係式隨溫度下降,亦即發生了
KT 變遷中普遍躍遷的現象。我們分別以 n=3及 n=5.1 定出兩種不同的
Tkt, 來討論電阻率的結果。由電阻率的結果分析,無論那種決定 Tkt 的
方法在介於78.1及78.6K 間,其ln(R/Rn)與[(Tco-T)/(T-Tkt)]成線性關係
。亦就是出現 KT 理論中預測因二維渦流運動產生的特殊行為。所以其具
有二維的傳導現象。
In order to know the dimensionalities of YBCO films, we
measured the resistivities and I-V curves of two YBCO films(120
o,240o). According to our results,the film of 240o thickness
couldn't show the 2d behaviors.The power law of 120o film has
the universal jump phenomena and the resisti- vity behavior can
be explained by 2d free vortices mo- tion.We can say that the
YBCO film of 120o thickness is a 2d system.
In order to know the dimensionalities of YBCO films, we
Fetal Monitoring in Open Fetal Surgery
No full textOpen surgery and fetoscopic surgery are of the safest procedures, whilst the ex-utero intrapartum treatment (EXIT) procedure has lost its significance as a result of the severe complications experienced both by the mother and the fetus. While uteroplacental circulation maintains, the EXIT is performed before delivery. The fetus is to be delivered at the conclusion of the case. A neonatal resuscitation area and two operating rooms are needed. Significant uterine relaxation is required for open midge station surgery. The risk for rapid bleeding and hemodynamic instability are the common accompanying parts of this procedure. It still continues to be a process done in certain centers not only in United States but also in Europe [1]
Combined Techniques in Difficult Airway Management
No full textDifficult or failed tracheal intubation is an important cause of mortality and morbidity. Approximately 30% of anesthesiarelated deaths are caused by the complications of difficult airway management. Also, 85% of respiratory complications result in brain damage or death [1]. Awake tracheal intubation is the most appropriate method for protection of airway reflexes in patients, who are expected or known to have difficult intubation. However, the use of video laryngoscope in awake patients in a way similar to the use of classic direct laryngoscope, which requires hanging of epiglottis or the use of fiber optic bronchoscope through nose, disturbs patients and complicates the procedure by causing gag reflex and mucosal bleeding
Numerical analysis and discussion on the hot-spot stress concept applied to welded tubular KT joints
No full textNominal stresses have been used for a long time for the assessment of fatigue resistance of welded joints, however, this approach has strong limitations since the definition of the nominal stress may be subjective for complex welded details and/or complex loading. On the other hand, the hot-spot stress approach has been proposed to overcome these limitations considering the structural geometrical discontinuities. However, the hot-spot stress methods also present certain limitations, and the present study aims at evaluating the available numerical and analytical hot-spot stress methods proposed by DNVGL (2016) and IIW (2014). The particular case of an offshore tubular KT joint has been considered herein and discretized in two planes. It has been studied numerically using the ABAQUS software coupled with the hot-spot stress extrapolation methods described in IIW (2014) and DNVGL (2016). The influence of the weld geometry has been considered and evaluated. In addition to the numerical method, the present study has also considered the analytical approach proposed in DNVGL (2016) derived from the combination of Efthymiou solutions for the stress concentration factor with the method of superposition of stresses. The numerical models according to IIW (2014) have been found to be more conservative when compared with the mesh-size methods proposed by DNVGL (2016), both in numerical modelling without the weld or with weld. For the numerical models with weld cord, the mean values of normalized difference index obtained for all braces together, as a result of comparing numerical results with analytical solutions, are lower, when compared with results obtained from the numerical models without weld cord.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Steel & Composite Structure
Effect of Stress Ratio(R) and Stress Concentration Factor (Kt) on Fatigue Properties of WSTi6211 Titanium Alloy
No full textIn this paper, the author studied the effects of different stress ratios（R） and stress concentration factors(Kt) on the fatigue properties of WSTi6211 titanium alloy.Through S-N curve, the author obtained the fatigue ultimate strength of the material under different conditions and analyzed characteristics of fatigue fractures, including the crack source sourse, the crack growth region and the final rupture region. The results show that when Kt=1, R=0.5, the fatigue ultimate strength σD is 626MPa; when Kt = 1, R=0.06, the fatigue ultimate strength σD is 527.5MPa; when Kt=3, R=0.06, the ultimate fatigue strength σD is 267MPa. Fatigue performance is very sensitive to R and Kt. The larger R is, the larger the fatigue ultimate strength is. The larger Kt is, the smaller the fatigue limit strength is. The fracture morphology shows typical fatigue fracture morphology. Most of the cracks originate on the surface of specimens and have typical fatigue bands. With the decrease of stress, the area of crack growth zone increases
Effect of Stress Ratio(R) and Stress Concentration Factor (Kt) on Fatigue Properties of WSTi6211 Titanium Alloy
No full textIn this paper, the author studied the effects of different stress ratios（R） and stress concentration factors(Kt) on the fatigue properties of WSTi6211 titanium alloy.Through S-N curve, the author obtained the fatigue ultimate strength of the material under different conditions and analyzed characteristics of fatigue fractures, including the crack source sourse, the crack growth region and the final rupture region. The results show that when Kt=1, R=0.5, the fatigue ultimate strength σD is 626MPa; when Kt = 1, R=0.06, the fatigue ultimate strength σD is 527.5MPa; when Kt=3, R=0.06, the ultimate fatigue strength σD is 267MPa. Fatigue performance is very sensitive to R and Kt. The larger R is, the larger the fatigue ultimate strength is. The larger Kt is, the smaller the fatigue limit strength is. The fracture morphology shows typical fatigue fracture morphology. Most of the cracks originate on the surface of specimens and have typical fatigue bands. With the decrease of stress, the area of crack growth zone increases
BARYON MAGNETIC-MOMENTS WITH CONFINED QUARKS
No full textAstronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)0ARTICLE3920-9234
XI(2230) IS LIKELY TO BE A GLUEBALL
No full textOn the basis of the recent results of xi(2230) --> pi(+)pi(-), p (p) over bar and xi(2230) --> K+K-, KsKs, measured by the BES Collaboration in J/psi radiative decays, combined with the PS185 experiment of p (p) over bar --> xi(2230) --> K (K) over bar, we argue that because of its very narrow partial decay widths to pi pi and K (K) over bar (less than 1 MeV), its large production rate in J/psi radiative decays (BR(J/psi --> gamma xi) > 2.3 x 10(-3) and its flavor-symmetric couplings to pi pi and K (K) over bar, the xi(2230) is very likely to be a J(PC) = (even)(++) glueball.Physics, MultidisciplinarySCI(E)中国科学引文数据库(CSCD)17ARTICLE3373-3762
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