DVD已死？

当Blu-ray和HD-DVD出现在我们面前时．很多人都认为DVD的时代将很快终结．不过．Arcam公司却以独特的视角向这种想法提出挑战。Arcam公司是一家专注于研发Hi-Fi系统和家庭影院系统的专业公司．它拥有强大的研发能力和对新兴但尚未成熟产品近乎“偏执”的怀疑习惯。这次．它将矛头对准了被人们寄予厚望的下一代高清存储标准——Blu-Ray和HD-DVD。     

The Experiment of Modulated Toroidal Current on HT-7 and HT-6M Tokamak

The Experiments of Modulated Toroidal Current were done on the HT-6M tokamak and HT-7 superconducting tokamak. The toroidal current was modulated by programming the Ohmic heating field. Modulation of the plasma current has been used successfully to suppress MHD activity in discharges near the density limit where large MHD m = 2 tearing modes were suppressed by sufficiently large plasma current oscillations. The improved Ohmic confinement phase was observed during modulating toroidal current (MTC) on the Hefei Tokamak-6M (HT-6M) and Hefei superconducting Tokamak-7 (HT-7). A toroidal frequency-modulated current, induced by a modulated loop voltage, was added on the plasma equilibrium current. The ratio of A.C. amplitude of plasma current to the main plasma current △Ip/Ip is about 12% ～ 30%. The different formats of the frequency-modulated toroidal current were compared.     

Modification of Boundary Parameters and Fluctuations by IBW and LHCD in the HT-7 Tokamak

Measurements of boundary parameters and their fluctuations have been performed in ohmic (OH) plasma and Ion Bernstein Wave (IBW) and Lower Hybrid Current Drive (LHCD) enhanced confinement plasma using a pneumatically driven Langmuir probe array on HT-7 toka-maX. In the enhanced confinement plasma~ the gradients of electron density and temperature become higher and a transport barrier comes into being in the vicinity of the limiter. The boundary potential shows a clear modification in the same region. The fluctuation levels are significantly depressed and the coherences between fluctuations are reduced evidently in the enhanced plasma.Meanwhile, we obtained the spectral features and the poloidal phase velocity of fluctuations us-ing a two-point correlation technique and found obvious modifications of the turbulence and the poloidal flow. The results suggest that the improved confinement in the IBW and LHCD enhanced plasma is at least partially due to the modification of the boundary parameters and the suppression of the boundary fluctuations and fluctuation induced fluxes.     

An application of the shortest path algorithm for the identification of weak MHD mode

The identification of magnetohydrodynamic(MHD) modes is a crucial issue in the control of magnetically confined plasmas. This paper proposes a novel method for identifying the evolution of MHD modes from a signal with a low signal-to-noise ratio. The proposed method generates a weighted directed graph from the time-frequency spectrum and calculates the evolution of the mode frequency by solving the shortest path. This method addresses the limitations posed by the lack of data channels and the di...     

Exploration of High Performance Scenarios in HL-2A

The HL-2A tokamak (R=1.64 m, a=0.32～0.4 m, k_x=1.3, δ_x=0.5, B_T=2.8T, I_p=0.48 MA) is under construction in SWIP. The main objectives of the project are to produce more adaptable divertor configuration to study energy exhaust and impurity     

NetEye Platform专用TCP/IP协议栈的优越性

NetEye防火墙拥有出色的线速处理能力和突出的访问控制力度,能够在路由模式和交换模式下实现对企业网络良好的防攻击服务,是国内新一代防火墙代表。这一切成就,在很大程度上可以归功于NetBye专用TCP/IP协议栈对NetEye Platform和NetEye“流过滤”技术强有力的支持。     

Simulation of reflectometry Bragg backscattering spectral responses in the absence of a cutoff layer

Experimental reflectometry signals obtained in the absence of a cutoff layer, with the possibility of interferometric operation excluded, show a coherent and recurrent frequency spectrum signature similar to an Alfvén cascade signature. A possible explanation resides in the modulation of a resonant Bragg backscattering response by an Alfvén mode structure located at the center of the plasma whose frequency of oscillation modulates the backscattered signal in a conformable way. This situation is modeled and simulated using an O-mode full-wave Maxwell finite-difference time-domain code and the resulting signatures are discussed.     

Machine learning application to predict the electron temperature on the J-TEXT tokamak

The reliability of diagnostic systems in tokamak plasma is of great significance for physics researches or fusion reactor. When some diagnostics fail to detect information about the plasma status, such as electron temperature, they can also be obtained by another method: fitted by other diagnostic signals through machine learning. The paper herein is based on a machine learning method to predict electron temperature, in case the diagnostic systems fail to detect plasma temperature. The fully-connected neural network, utilizing back propagation with two hidden layers, is utilized to estimate plasma electron temperature approximately on the J-TEXT. The input parameters consist of soft x-ray emission intensity, electron density, plasma current, loop voltage, and toroidal magnetic field, while the targets are signals of electron temperature from electron cyclotron emission and x-ray imaging crystal spectrometer. Therefore, the temperature profile is reconstructed by other diagnostic signals, and the average errors are within 5%. In addition, generalized regression neural network can also achieve this function to estimate the temperature profile with similar accuracy. Predicting electron temperature by neural network reveals that machine learning can be used as backup means for plasma information so as to enhance the reliability of diagnostics.     

X-ray flares in early GRB afterglows

The Swift X-ray Telescope (XRT) has discovered that flares are quite common in early X-ray afterglows of gamma-ray bursts (GRBs), being observed in roughly 50% of afterglows with prompt follow-up observations. The flares range in fluence from a few per cent to approximately 100% of the fluence of the prompt emission (the GRB). Repetitive flares are seen, with more than four successive flares detected by the XRT in some afterglows. The rise and fall times of the flares are typically considerably smaller than the time since the burst. These characteristics suggest that the flares are related to the prompt emission mechanism, but at lower photon energies. We conclude that the most likely cause of these flares is late-time activity of the GRB central engine.     

羧甲基裂褶多糖的制备及其保湿活性研究

通过响应面试验研究氯乙酸与裂褶多糖质量比,反应时间,反应温度对裂褶多糖的羧甲基化取代度的影响。采用体外重量法和体表仪器法,与常用化妆品保湿剂甘油和透明质酸比较,研究羧甲基裂褶多糖的保湿功效。响应面实验结果表明,氯乙酸与裂褶多糖质量比为2.38,反应温度为61.58℃,反应时间为2.82 h时有最大取代度0.54。体外保湿试验结果表明:在相对湿度为43%和81%条件下,吸湿性大小顺序为羧甲基裂褶多糖甘油透明质酸裂褶多糖;在干燥硅胶环境下,保湿性大小为甘油裂褶多糖羧甲基裂褶多糖透明质酸;在相对湿度为43%条件下,保湿性大小顺序为甘油羧甲基裂褶多糖透明质酸裂褶多糖。体表保湿试验结果表明:羧甲基裂褶多糖保湿效果显著优于透明质酸,低于甘油,但是其锁水保湿性强于甘油和透明质酸。