Interaction of a surface acoustic wave with a two-dimensional electron gas

When a surface acoustic wave propagates on the surface of a GaAs semiconductor, coupling between electrons in the two-dimensional electron gas beneath the interface and the elastic host crystal through piezoelectric interaction will attenuate the SAW. The coupling coefficient is calculated for the SAW propagating along an arbitrary direction. It is found that the coupling strength is largely dependent on the propagating direction. When the SAW propagates along the [011] direction, the coupling becomes quite weak.Comment: 3 figure

TZC: Efficient Inter-Process Communication for Robotics Middleware with Partial Serialization

Inter-process communication (IPC) is one of the core functions of modern robotics middleware. We propose an efficient IPC technique called TZC (Towards Zero-Copy). As a core component of TZC, we design a novel algorithm called partial serialization. Our formulation can generate messages that can be divided into two parts. During message transmission, one part is transmitted through a socket and the other part uses shared memory. The part within shared memory is never copied or serialized during its lifetime. We have integrated TZC with ROS and ROS2 and find that TZC can be easily combined with current open-source platforms. By using TZC, the overhead of IPC remains constant when the message size grows. In particular, when the message size is 4MB (less than the size of a full HD image), TZC can reduce the overhead of ROS IPC from tens of milliseconds to hundreds of microseconds and can reduce the overhead of ROS2 IPC from hundreds of milliseconds to less than 1 millisecond. We also demonstrate the benefits of TZC by integrating with TurtleBot2 that are used in autonomous driving scenarios. We show that by using TZC, the braking distance can be shortened by 16% than ROS

Light-Cone Sum Rules Analysis of ΞQQ′q→ΣQ′∗\Xi_{QQ^{\prime}q}\to\Sigma_{Q^{\prime}}^{*} Weak Decays

In this work, we investigate the semi-leptonic weak decays of spin-1/2 doubly-heavy baryons $\Xi_{QQ^{\prime}}$ into spin-3/2 singly-heavy baryons $\Sigma_{Q^{\prime}}^*$ within light-cone sum rules. Using the parallel components of the light-cone distribution amplitudes of $\Sigma_{Q^{\prime}}^*$, the transition form factors for these decays are calculated both analytically and numerically. The numerical results for these semi-leptonic weak decays widths and branching ratios are also predicted, which are compared with the same predictions by other theoretical approaches in the literatures. These phenomenology predictions can be tested by the experiments in the future.Comment: 19 pages, 2 figures, 4 table

The Compressive Strength of Cement–Slag–Calcium Sulphoaluminate Ternary System

At present, there is an increasing interest on the use of calcium sulphoaluminate (C4A3$) in cement. In this paper, pure mineral of sulphoaluminate (C4A3$) was prepared in laboratory. Different dosages of steel slag and C4A3$were blended into cement. The aim of this paper is to investigate the compressive strength of this ternary system. The test results show that the addition of C4A3$ can improve the strength of cement. Larger C4A3$dosage (7$ dosage is 5%. In ternary system, C4A3$ has no obvious improvement, while 5% dosage could improve the strength a little