Prescribed-time stabilisation control of differential driven automated guided vehicle

The position control problem of differential-driven automated guided vehicles(AGVs)based on the prescribed-time control method is studied.First,an innovative orientation error function is proposed by an auxiliary arcsine function about the orientation angle.Thus,the problem of position control of AGV is transformed into the stabilisation control of the kinematic system.Second,by introducing a reserved time parameter and a smooth switching function,a novel time-varying scaling function is proposed.This novel scaling function avoids the risk of infinite gain in the conventional prescribed-time control method while ensuring the smoothness of control laws.Then,an improved velocity constraint function is proposed using the Gaussian function.Compared with the existing constraint function,the proposed method not only has more smoothness but also solves the balance point errors caused by the large AGV orientation errors.The presented method ensures that the AGV reaches the target position in a prescribed time.Hence,the upper bound of the AGV system state can be determined by adjusting parameters.Matlab simulation results show that the proposed controller can effectively make the AGV system state satisfy the prescribed bound.

Shape-Controlled Synthesis of Mn_(3)O_(4) Nanocrystals and Their Catalysis of the Degradation of Methylene Blue

Various sizes and shapes of Mn_(3)O_(4) nanocrystals have been prepared in a one-pot synthesis in extremely dilute solution by soft template self-assembly. To better control size and shape, the effects of varying the growth time, reaction temperature, surfactant, and manganese source were examined. The average size of octahedral Mn_(3)O_(4) crystallites was found to be related to the reaction time, while higher reaction temperature (150 °C) and the use of a cetyltrimethylammonium bromide/poly(vinylpyrrolidone) (CTAB/PVP) mixture allowed construction of a better-defined octahedral morphologies. When PVP or poly(ethylene oxide)-poly(propylene oxide) (P123) was used as template, large-scale agglomeration resulting in loss of the octahedral morphology occurred and crystallites with a quasi-spherical shape were obtained. The nano-octahedral crystallites were shown to be an efficient catalyst for the oxidation of methylene blue.

Multigene editing via CRISPR/Cas9 guided by a single-sgRNA seed in Arabidopsis

We report that a solo single-guide RNA （sgRNA） seed is capable of guiding Clustered Regularly Interspaced Short Palindromic Repeats （CRISPR）/CRISPR -associated 9 （CRISRP/Casg） to simultaneously edit multiple genes AtRPL10A, AtRPL10B and AtRPL10C in Arabidopsis. Our results also demonstrate that it is possible to use CRISPR/Cas9 technology to create AtRPLlo triple mutants which otherwise cannot be generated by conventional genetic crossing. Compared to other conventional multiplex CRISPR/Cas systems, a single sgRNA seed has the advantage of reducing off-target gene-editing. Such a gene editing system might be also applicable to modify other homologous genes, or even less-homologous sequences for multiple gene-editing in plants and other organisms.

非传统吸油剂:疏水皮肤层的亲水海绵用于高效溢油清理

基于多孔材料的油水分离为解决溢油污染问题提供了一个有前景的途径.传统上,为了实现选择性吸油,多孔材料需要用低表面能化学试剂进行充分的疏水处理,以赋予其疏水/亲油特性.然而,这种充分的疏水处理既导致了高成本,又由于过度的化学试剂消耗增加了环境危害,阻碍了其实际应用.在此,我们通过一种简单的液体薄膜浸渍技术,开发了一种替代性的吸油剂,即具有疏水皮肤层的亲水海绵.与传统的全疏水吸油剂不同,我们制备的海绵只有最外层用疏水聚二甲基硅氧烷(PDMS)涂层进行了改性,疏水化学试剂消耗减少达80%.该海绵疏水皮肤层阻挡了水的进入,而内部亲水主体促进了油的吸收,因此可以从油水混合物中高度选择性吸收油.更重要的是,这种皮肤层结构海绵表现出增强的吸油速度.与传统的疏水海绵相比,在吸收相同质量原油时,吸收时间可减少36%.这主要归功于其亲水内部通道相比于传统吸油剂疏水通道具有更强大的毛细管吸收作用.此外,该海绵还显示出比完全疏水海绵更强的吸收容量.这项研究提供了一个开发具有增强吸油性能的低成本、环境友好吸油剂的通用策略.

Social relation and physical lane aggregator:integrating social and physical features for multimodal motion prediction

Purpose–The purpose of this paper aims to model interaction relationship of traffic agents for motion prediction,which is critical for autonomous driving.It is obvious that traffic agents’trajectories are influenced by physical lane rules and agents’social interactions.Design/methodology/approach–In this paper,the authors propose the social relation and physical lane aggregator for multimodal motion prediction,where the social relations of agents are mainly captured with graph convolutional networks and self-attention mechanism and then fused with the physical lane via the self-attention mechanism.Findings–The proposed methods are evaluated on the Waymo Open Motion Dataset,and the results show the effectiveness of the proposed two feature aggregation modules for trajectory prediction.Originality/value–This paper proposes a new design method to extract traffic interactions,and the attention mechanism is used in each part of the model to extract and fuse different relational features,which is different from other methods and improves the accuracy of the LSTM-based trajectory prediction method.

Path following of underactuated vehicles via integral line of sight guidance and fixed‐time heading control

This study investigates the integral line of sight(ILOS)path‐following control problem of surface vehicles whose dynamics feature external disturbances,model uncertainties,and actuator dead zones.First,introducing the ILOS guidance law,the path‐following control problem is converted to stabilising a 2nd order nonlinear system.Subsequently,the fixed‐time observer is designed to estimate and compensate for the uncertainties and unknown external disturbances while overcoming the actuator dead zones.Finally,the trajectory tracking control strategy is designed based on the fixed‐time observer.Numerical ex-amples are given to illustrate the effectiveness of the proposed approaches.