7T大口径NbTi超导磁体降温通电实验

介绍了用于超导导体测试用超导磁体降温通电实验,降温采用500W@4.5K制冷机系统。300—10K直接采用冷He气循环冷却超导磁体,温度低于10K直接输入LHe。该磁体在4.2K温度下可通1000A的电流,其中心磁场为7T,储能为3M J。     

<Emphasis Type="Italic">Brevibacillus sp</Emphasis>: A Novel Thermophilic Source for the Production of Bile Salt Hydrolase

A thermophilic microorganism growing within the temperature range of 40–65 °C (optimum at 55 °C) was isolated from hot water springs near Konkan, Maharashtra, India. Based on 16S rDNA sequence analysis, it was concluded that the isolate belongs to the genus Brevibacillus. The present paper reports the isolation, identification, and standardization of fermentation conditions for the production of enzyme, bile salt hydrolase (EC 3.5.1.24) which is produced intracellularly at high temperatures. This is the first report regarding the production of bile salt hydrolase from a thermophilic source. Optimization of fermentation conditions resulted in a 2.9-fold enhancement in enzyme production.     

微量稀土对奥氏体耐热钢高温力学性能的影响

研究了微量稀土对Cr21Ni11N奥氏体耐热不锈钢高温热塑性及高温持久性能的影响.结果表明:在750～1250℃范围内,稀土显著提高耐热钢的热塑性,消除800℃的塑性低凹区,扩宽安全热加工温度范围近75℃.稀土显著延长耐热钢的高温持久寿命约3～5倍,并提高持久断裂塑性.钢中添加稀土后,其蠕变断裂机制由楔形裂纹为主的机制逐渐转变为空洞裂纹为主的机制,高温持久断口附近的楔形裂纹明显减少,且断口呈典型的韧窝状塑性断口特征.     

Dynamic modelling and simulation of a hot strip finishing mill

Hot rolling is an essential industrial process in the production of sheet steel, a widely used product in manufacturing and construction. A finishing mill performs a set of operations in a hot strip rolling mill, and is a complex unit including many processes and control loops. Its modelling is a challenging task due to the variety of phenomena that occur within the mill, and variable transport delays. Model validation is also challenging due to a scarcity of measurements. On the other hand, a dynamic model that adequately reflects the numerous interactions between the mill units can be very useful for tasks such as high performance control design or vibration analysis. In this study, a one-dimensional model has been developed and validated against real plant data. The end use of the model is intended to be looper control analysis, but the model is kept sufficiently general so that it can be used or easily extended for other applications.     

“Hot Potato Voice” in Peritonsillitis: A Misnomer

The "hot potato voice" is widely recognized as a symptom of peritonsillar cellulitis or abscess; yet there have been no studies assessing the resonance characteristics of the vocal tract in peritonsillitis. Analysis was undertaken of formant frequencies in the articulation of the vowels /i:/. /a:/ and /u:/ in six subjects with peritonsillitis and compared with articulation once the peritonsillitis had settled. Significant variation was found in F1 when articulating /i:/ and in F2 when articulating /a:/, which are explainable by dyskinesis of the peritonsillar musculature. These findings were compared with six subjects articulating the same vowels with and without a hot potato in their mouth. Variation was found in both F1 and F2 when articulating /i:/, which can be related to interference of the potato with movement of the anterior tongue. The changes in the vocal tract differ in these two cases and the title "hot potato voice" in peritonsillitis is a misnomer.     

Kadomtsev-Petviashvili (KP) Burgers Equation in Dusty Negative Ion Plasmas: Evolution of Dust-Ion Acoustic Shocks

We study the nonlinear propagation of dust-ion acoustic (DIA) shock waves in an un-magnetized dusty plasma which consists of electrons, both positive and negative ions and negatively charged immobile dust grains. Starting from a set of hydrodynamic equations with the ion thermal pressures and ion kinematic viscosities included, and using a standard reductive perturbation method, the Kadomtsev-Petviashivili-Burgers (K-P-Burgers) equation is derived, which governs the evolution of DIA shocks. A stationary solution of the K-P-Burgers equation is obtained and its properties are analysed with different plasma number densities, ion temperatures and masses. It is shown that a transition from shocks with negative potential to positive one occurs depending on the negative ion concentration in the plasma and the obliqueness of propagation of DIA waves.     

Effects of electron temperature on dielectric function and localization of laser beams in underdense collisional plasma

Effects of electron temperature on dielectric function and localization of laser beams in underdense collisional plasmas are investigated. Simulation results show that the electron temperature has a strong effect on the dielectric constant and the laser beam localization. It is observed that due to the influence of the electron temperature, the dielectric function presents some interesting and complicated nonlinear variations, and gives rise to the laser beam localization. Moreover, the amplitudes of the beam width and the beam intensity are subjected to continuously oscillatory variation in the region of localization. In addition, the effects of several parameters on the dielectric function and the beam localization are discussed.     

全电离氢等离子体的电导率

主要研究了全电离等离子体的散射相移、传输截面和电导率.相移应用WKB方法计算,且计算结果与使用精确计算方法得到的结果非常一致,证明了所用计算方法的正确性和准确性.在对传输截面的计算中,观察到了形状共振,这种共振是由于半束缚态的消失产生的.电导率的计算应用了Chapman-Enskog方法,并与其它理论和实验结果进行了比较.     

Atomic structure and transition properties of H-like Al in hot and dense plasmas

The atomic structure and transition properties of H-like Al embedded in hot and dense plasmas are investigated using modified GRASP2 K code. The plasma screening effect on the nucleus is described using the self-consistent field ion sphere model. The effective nuclear potential decreases much more quickly with increasing average free electron density,but increases slightly with increasing electron temperature. The variations of the transition energies, transition probabilities,and oscillator strengths with the free electron density and electron temperature are the same as that of the effective nuclear potential. The results reported in this work agree well with other available theoretical results and are useful for plasma diagnostics.