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In this paper, dynamic characteristics of the single-crystal GaN-passivated lateral AlGaN/GaN Schottky barrier diodes (SBDs) treated with proton irradiation were investigated. Radiation-induced changes including idealized Schottky interface and slightly degraded on-resistance (RON) were observed with 10-MeV proton irradiation at fluences of 1014 cm-2. Benefited from the existing negative polarization charges induced at GaN/AlGaN interface, the dynamic on resistance (RON,dyn) showed negligible degradation after a 1000-s-long forward current stress of 50 mA for devices irradiated or not. Furthermore, the normalized RON,dyn increased by only 14% than the initial case after a 100-s-long bias of -600 V for the irradiated devices. The high-performance lateral AlGaN/GaN SBDs with tungsten as anode metal and in-situ single-crystal GaN as passivation layer show a great potential in the harsh radiation environment of space.

In order to study the process and characteristic of the fragments in the warhead with one end cap under full constraint condition, we established a cylindrical casing with two end caps which one of them was fully constrained using the simulation analysis. The result showed that the fragmentation of cylindrical casing with one end full constrained has its own characteristic. The Mach stem was generated when the detonation wave propagated to the fully constrained end cap under the condition of one end detonation, working on unreactive explosives and causing the nearby fragment subjected to nearly 2.5 times the normal pressure to obtain a higher speed. The cylindrical casing first ruptured at the contact surface with the fully constrained end, and then at the end cover of the initiating end, and then the rupture extends to the whole cylindrical casing. The detonation products started to leak out from the rupture. driving fragments to fly, and forming two dense flying areas. The analysis of this paper can provide a reference for the optimal design of this kind of warhead.

Attribute-based access control is an effective cryptographic mechanism that allows a data owner to perform attribute-level access control over users’ access capabilities. In the application background of blockchain, it is urgent to use attribute-based access control to solve a series of security problems. Although there exist several similar schemes, they do not consider attribute revocation. By adopting the attribute revocation technique based on binary trees, we extended Waters’ ciphertext policy attribute-based encryption (CP-ABE) scheme into a revocable CP-ABE (RCP-ABE) scheme. By combining our RCP-ABE with blockchain, we constructed a revocable attribute-based access control system. The new system supports expressive access control policies and allows the attribute authority to revoke users’ attributes or part of their attributes. The security analysis shows that the new system satisfies several ideal properties, i.e., forward security, backward security, confidentiality, and integrity.

In this paper, the microstructure of laser cladding layer was studied under two laser conditions. The microstructure of laser cladding layer was characterized as directional rapid solidification. On the premise of forming a good metallurgical bond between the coating and the matrix, higher laser energy density was harmful to refine the coating structure and reduce the microhardness of the coating.

Growing semiconductor laser sources on silicon is a crucial but challenging technology for developing photonic integrated circuits (PICs). InAs/GaAs quantum dot (Qdot) lasers have successfully circumvented the mismatch problem between III–V materials and Ge or Si, and have demonstrated efficient laser emission. In this paper, we review dynamical characteristics of Qdot lasers epitaxially grown on Ge or Si, in comparison with those of Qdot lasers on native GaAs substrate. We discuss properties of linewidth broadening factor, laser noise and its sensitivity to optical feedback, intensity modulation, as well as mode locking operation. The investigation of these dynamical characteristics is beneficial for guiding the design of PICs in optical communications and optical computations.

The initial velocity of fragment from cylindrical casing, which detonates at one end along the central of the casing, is the key issue in the field of explosion technology and its protecting. Most of the formula available can predict the initial velocity or the velocity of fragments at middle part of the cylindrical casing with greater length-dimeter ratio (L/d>2). However, when the length-diameter ratio is less than two, the initial velocity of the cylindrical casing filled with explosives will have a big difference. In the present work, a numerical simulation model acknowledged by X-ray radiography experiments was used to determine the influence of the length-diameter ratio. The formula was built on top of the Gurney formula and made use of a correctional function to account for the effect of the length-dimeter ratio. The formula was further acknowledged with the established numerical simulation model. The results indicate that the calculation formula can accurately predict the initial fragment velocity with different length-diameter ratio (L/d⩽ 2).

Ion's behavior plays an important role in plasma etching processes and is determined by the local electric potential in the etched trenches. In this study, with the trench powered by a radio frequency (rf) source, the Laplace equation is solved to obtain the electric potential. The ion trajectories and the ion energy distribution (IED) at the bottom of the trench are obtained self-consistently by tracking the ions in the trench. The results show that the aspect ratio of depth- to-width of the photoresist trench and the voltage amplitude of the rf source applied to the electrode are important parameters. The larger the aspect ratio and the smaller the amplitude are, the more ions hit the sidewalls, which results in a notching phenomenon. Meanwhile, there are a higher high-energy peak and a lower low-energy peak in the IED with the increase in aspect ratio.

In the present work, a series of [Fe80Ni20—O/SiO2]n multilayer thin films is fabricated using a reactive magnetron sputtering equipment. The thickness of SiO2 interlayer is fixed at 3 nm, while the thickness values of Fe80Ni20—O magnetic films range from 10 nm to 30 nm. All films present obvious in-plane uniaxial magnetic anisotropy. With increasing the Fe80Ni20—O layer thickness, the saturation magnetization increases slightly and the coercivity becomes larger due to the enlarged grain size, which could weaken the soft magnetic property. The results of high frequency magnetic permeability characterization show that films with thin magnetic layer are more suitable for practical applications. When the thickness of Fe80Ni20—O layer is 10 nm, the multilayer film exhibits the most comprehensive high-frequency magnetic property with a real permeability of 300 in gigahertz range.