钛酸钾晶须对热硫化硅橡胶性能的影响

研究了钛酸钾晶须对热硫化硅橡胶复合材料的硫化特性、力学性能及热稳定性的影响,通过扫描电镜观察了复合材料的断面及晶须在基体中的分散性。结果表明:钛酸钾晶须能促进硅橡胶的硫化,提高其最高扭矩;同时,钛酸钾晶须对硅橡胶具有一定的补强作用,拉伸强度、硬度等随晶须用量的增加而增大;钛酸钾晶须的引入,使硅橡胶复合材料的热稳定性明显提高,填充量为9vol%时,与纯硅橡胶相比,复合材料的热分解温度提高了65℃,Kissinger法求出填充量为12vol%的钛酸钾晶须/硅橡胶复合材料的热分解活化能为193.62kJ/mol,高于相同填充量的白炭黑/硅橡胶复合材料,具有较好的热稳定性。     

Effects of Magnetic Coupling of Temperature Profile of Black—Hole Accretion Disc

We propose a model of the magnetic coupling (MC) of a retating black hole(BH) with the surrounding accretion disc in order to study the radial temperature profile in the inner region of the disc,in which a linear map from the angular coordinate on the BH horizon to the radial coordinate on the thin disc is given by closed magnetic field lines.The MC power and torque are derived using a modified equivalent circuit.It is shown that the MC effects on the temperature profile are related intimately to the BH spin,resulting in the variation of the value and the position of the peak temperature.It turns out that the value range of the colour temperature of the disc is extended by the MC effects.     

Parameter Space for Evolution of Black Hole Systems and Gamma—Ray Bursts

An analytical model of black hole(BH) evolution is proposed by considering the Blandford-Znajek process with a tansient magnetized accretion disc,which is used as a central engine for powering gamma ray bursts(GRBs),The state of BH evolution can be described by the representative points in the corresponding sub-regions of a parameter space.It is shown that the BH spin might be spun up rather than slowed down.provided that the ratio of the angular velocity of the magnetic field lines to that of the BH horizon is greater than a critical value.In addition,the effects of some initial values of the BH system on the evolution terminals and the output energy for GRBs are discussed in the parameter space.     

Coexistence of Two Mechanisms for Extracting Energy from a Rotating Black Hole

Evolution characteristics of a rotating black hole (BH) are discussed in coexistence of the Blandford-Znajek (BZ) process and the magnetic coupling (MC) process in the parameter space consisting of the BH spin and the power-law index of the magnetic field on the disc. The condition for the coexistence of the two energy mechanisms are derived by using the mapping relation between the angular coordinate on the BH horizon and the radial coordinate on the disc. It is shown that not only the two mechanisms can coexist, but also the power and the rate of change of BH entropy in the BZ process will dominate over those in the MC process, provided that the BH spin and the power-law index are great enough.     

A Toy Model for Magnetic Field Configurations in Black Hole Accretion Discs

We discuss the feature of the magnetic field configuration arising from double counter oriented electric currentrings in the accretion disc around a Kerr black hole （BH）. We discuss the relevant physical quantities corresponding to this configuration： （1） the power and torque transferred by the large-scale magnetic field, （2） the angular momentum and energy fluxes transferred from the BIt to the inner disc, （3） the radiation flux from the disc. In addition, we discuss the possibility that the closed magnetic field anchored at the disc probably evolves to the open magnetic field, which is helpful to produce the jet from the disc.