Emerging Internet of Things driven carbon nanotubes-based devices

Carbon nanotubes (CNTs) have attracted great attentions in the field of electronics, sensors, healthcare, and energy conversion. Such emerging applications have driven the carbon nanotube research in a rapid fashion. Indeed, the structure control over CNTs has inspired an intensive research vortex due to the high promises in electronic and optical device applications. Here, this in-depth review is anticipated to provide insights into the controllable synthesis and applications of high-quality CNTs. First, the general synthesis and post-purification of CNTs are briefly discussed. Then, the state-of-the-art electronic device applications are discussed, including field-effect transistors, gas sensors, DNA biosensors, and pressure gauges. Besides, the optical sensors are delivered based on the photoluminescence. In addition, energy applications of CNTs are discussed such as thermoelectric energy generators. Eventually, future opportunities are proposed for the Internet of Things (IoT) oriented sensors, data processing, and artificial intelligence.

Sliding-mode variable structure control for complex automatic systems: a survey

<abstract> <p>Automatic systems (ASs) can automatically control the work of controlled objects without unattended participation. They have been extensively used in industry, agriculture, automobiles, robots and other fields in recent years. However, the performance of the controller cannot meet the work requirements under complex environmental conditions. Therefore, improving the control performance is one of the difficult problems that automated systems should solve. Sliding-mode variable structure control has the advantages of fast response, insensitivity to uncertainty and interference and easy implementation; thus, it has been extensively used in the field of complex control systems. This article analyses and explains the research status of motors, microgrids, switched systems, aviation guidance, robots, mechanical systems, automobiles and unmanned aerial vehicles (UAVs) and prospects for the application of sliding-mode variable structure control in complex ASs.</p> </abstract>

Piezoelectric Voltage Constant and Sensitivity Enhancements Through Phase Boundary Structure Control of Lead-free (K,Na)NbO3-based ceramics

The piezoelectric voltage constant (g33) is a material parameter critical to piezoelectric voltage-type sensors for detecting vibrations or strains. Here, we report a lead-free (K,Na)NbO3 (KNN)-based piezoelectric accelerometer with voltage sensitivity enhanced by taking advantage of a high g33. To achieve a high g33, the magnitudes of piezoelectric charge constant d33 and dielectric permittivity er of KNN were best coupled by manipulating the intrinsic polymorphic phase boundaries effectively with the help of Bi-based perovskite oxide additives. For the KNN composition that derives benefit from the combination of er and d33, the value of g33 was found to be 46.9 ´ 10-3 V·m/N, which is significantly higher than those (20 - 30 ´ 10−3 V·m/N) found in well-known polycrystalline lead-based ceramics including commercial Pb(Zr,Ti)O3 (PZT). Finally, the accelerometer sensor prototype built using the modified KNN composition demonstrated higher voltage sensitivity (183 mV/g) when measuring vibrations, showing a 29% increase against the PZT-based sensor (142 mV/g).

A Hierarchical Structure Control Strategy Based on MPC for a Six-DOF Flexible Joint Manipulator

The six-degree-of-freedom flexible joint manipulator is a complex system that suffers from the problem that the trajectory planning results are inconsistent with the control results. To keep the planned trajectory within the control range of the manipulator, a hierarchical structure control strategy is designed, which consists of a trajectory planning layer, a model predictive control layer, and a bottom control layer. Specifically, first, the target joint angles are obtained by a time-optimal trajectory planning algorithm based on a genetic algorithm in the trajectory planning layer. Second, in the model predictive control layer, considering the system physical constraints, the model predictive controller is adopted to provide the set points for the Proportion-Differentiation (PD) controllers. Finally, in the bottom control layer, the manipulator moves along the target trajectory under the PD controllers with the feedback control law. The simulation results show that, compared with the PD control strategy, the hierarchical structure control strategy can achieve better control performance and reduce the tracking error of the terminal trajectory by 33.70%.

HIGH-TEMPERATURE CONSOLIDATION AS A STRUCTURE CONTROL METHOD OF THE NANOPOROUS GLASSES

Nanoporous glass is a matrix for composite optical materials, in which, by impregnating various activators, it is possible to initiate the appearance of properties that are uncharacteristic for the composite materials. In this case, the main parameter of the structure of nanoporous glass is porosity, which can be controlled by the method of high-temperature consolidation. In this work, we have studied the effect of temperature consolidation on the structure of porous glass.

CONTROL OF REMOTELY OPERATED UNDERWATER VEHICLE USING MODEL PREDICTIVE CONTROL

This paper focuses on application of model predictive control on attitude control of remotely operated underwater vehicle. These vehicles are used in scientific, defence and oceanography applications. Remotely Operated Vehicle (ROV) considered in this paper is nonlinear model and complex. MPC is applied on ROV model to track in desired set point trajectories in the presence of uncertainties. Simulation has been carried out in MATLAB environment. Model Predictive Control has given significantly good results compared to PID, Adaptive and Variable structure control.