Lane-Change Collision Avoidance Control for Automated Vehicles with Control Barrier Functions

Ding Yang,Zhong Hong,Qian Yahui,Wang Liangmo,Xie Yuan 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.3

In congested street or highway scenarios, such as lane-change in dynamically changing traffic flow situations, the planning and tracking of trajectories for connected and automated vehicles (CAVs) represent some of the most challenging tasks. As an introduction to automated lane-change in CAVs, this paper presents a control Lyapunov function (CLF) approach that follows an optimal desired trajectory while observing the constraints imposed by the control barrier function (CBF) in order to avoid collision with surrounding vehicles. By combining CLF and CBF within the framework of quadratic programs (QP), it allows the implementation to simultaneously track the control objective (represented by the CLF) and satisfy the constraints of the desired state of the system (represented by the CBF). Therefore, it provides the possibility of tracking simultaneously the path of the unmanned vehicle, within the constraints of the surrounding vehicles as well as the surrounding environment. From simulations and comparison results, the controller presented here can perform collision avoidance well and can be used on a real traffic system, which has the advantage of providing faster and more precise lane-change results than another work.

Enhancement of Mechanical and Thermal Properties of SU‑8 Photoresist with Multilayer Woven Glass Fabric Based on Micromachining Technology

Wenwen Zhou,Yahui Li,Yunna Sun,Jinyuan Yao,Xutong Song,Guifu Ding 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.6

SU-8 photoresist has been more and more widely used as a structural material in micro electromechanical system (MEMS) because of its low cost and excellent biocompatibility. However, the inferior mechanical and thermal performances immensely impinge the reliability of the MEMS device based SU-8 and accordingly restrict its application. Here we report the mechanicaland thermal performance of SU-8 reinforced by the multilayer glass fabric with the MEMS technology. The finite element simulation and specific experiment are conducted, which confirm that the reinforced SU-8 composites have a 281% increase in Young’s modulus and a 64% decrease in coefficient of thermal expansion (CTE) compared with pure SU-8. Additionally,the improved mechanism has also been analyzed, including the excellent interface bonding between the SU-8 and glass fabric, and the high-bond energy of Si–O-Si chain structures in glass fabric. Furthermore, the glass fabric reinforced SU-8 could still possess a high light transmittance to maintain the ability of lithography patterning. Therefore, it is believed thatthe strategy proposed here may satisfy higher requirements of MEMS devices, which guarantees its practical applications in the functional microstructures.

Enzymatic Manufacture of Deoxythymidine-5`-Triphosphate with Permeable Intact Cells of E. coli Coexpressing Thymidylate Kinase and Acetate Kinase

( Jiao Zhang ),( Yahui Qian ),( Qingbao Ding ),( Ling Ou ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.12

A one-pot process of enzymatic synthesis of deoxythymidine-5`-triphosphate (5`-dTTP) employing whole cells of recombinant Escherichia coli coexpressing thymidylate kinase (TMKase) and acetate kinase (ACKase) was developed. Genes tmk and ack from E. coli were cloned and inserted into pET28a(+), and then transduced into E. coli BL21 (DE3) to form recombinant strain pTA in which TMKase and ACKase were simultaneously overexpressed. It was found that the relative residual specific activities of TMKase and ACKase, in pTA pretreated with 20 mM ethylene diamine tetraacetic acid (EDTA) at 25℃ for 30 min, were 94% and 96%, respectively. The yield of 5`-dTTP reached above 94% from 5 mM deoxythymidine 5`-monophosphate (5`-dTMP) and 15 mM acetyl phosphate catalyzed with intact cells of pTA pretreated with EDTA. The process was so effective that only 0.125 mM adenosine-5`-triphosphate was sufficient to deliver the phosphate group from acetyl phosphate to dTMP and dTDP.

Simultaneous Collision Avoiding and Target Tracking for Unmanned Ground Vehicle with Velocity and Heading Rate Constraints

Zhaoyang Cuan,Da-Wei Ding,Heng Wang,Yahui Liu,Yulong Liu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.4

This paper develops a novel control method for solving the challenging problem of simultaneous collision avoidance and target tracking for an unmanned ground vehicle with velocity and heading rate constraints. The problem is formulated as an optimization problem where the trajectory tracking is treated as a soft constraint via control Lyapunov functions and obstacles avoidance is treated as hard constraint via control barrier functions. Two constraints are naturally unified in the context of quadratic programs which ensure that the hard constraint, soft constraint, velocity and heading rate constraints are satisfied simultaneously. Under the proposed strategy, an unmanned ground vehicle can avoid the stationary and moving obstacles while tracking the desired trajectory precisely and smoothly. Finally, three representative simulations are provided to demonstrate the effectiveness of the proposed method.

One-pot Process of 2'-Deoxyguanylic Acid Catalyzed by a Multi-enzyme System

Yanyu Li,Qingbao Ding,Ling Ou,Yahui Qian,Jiao Zhang 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.1

2'-Deoxyguanylic acid (deoxyguanosine-5'-monophosphate, dGMP) is a substance required by livingcells that is used extensively in reagents, fine chemicalsand other industrial fields. Traditionally, dGMP is separatedfrom DNA degradation products, which is low-yieldingand time-consuming. Herein, we investigated a novel, onepotmulti-enzymatic cascade reaction to produce dGMP. This reaction involved purine nucleoside phosphorylase(PNPase) and acetate kinase (ACKase) from Escherichiacoli, N-deoxyribosytransferase II (NDT-II) from Lactobacillusdelbrueckii and deoxyguanosine kinase (dGKase) fromBacillus subtilis. During the reaction, the initial guanosinesubstrate was cleaved into guanine and ribose-1-phosphateby PNPase. Then, deoxyguanosine (dGR) was subsequentlyproduced from a reaction between guanine and thymidinecatalysed by NDT-II. Finally, the intermediate dGR wasphosphorylated to dGMP by dGKase and a cytidinetriphosphate (CTP) regeneration system that utilised acetylphosphate via ACKase. A very small amount of CTP wasadded because CTP regeneration was efficient to transfer aphosphate group from acetyl phosphate to dGR. After 12 hof incubation, a maximal dGMP yield of up to 76% wasobtained based on the addition of 5 mM guanosine and 5mM thymidine.

Electrical stimulation as a novel tool for regulating cell behavior in tissue engineering

Cen Chen,Xue Bai,Yahui Ding,이인섭 한국생체재료학회 2019 생체재료학회지 Vol.23 No.4

Recently, electrical stimulation as a physical stimulus draws lots of attention. It shows great potential in disease treatment, wound healing, and mechanism study because of significant experimental performance. Electrical stimulation can activate many intracellular signaling pathways, and influence intracellular microenvironment, as a result, affect cell migration, cell proliferation, and cell differentiation. Electrical stimulation is using in tissue engineering as a novel type of tool in regeneration medicine. Besides, with the advantages of biocompatible conductive materials coming into view, the combination of electrical stimulation with suitable tissue engineered scaffolds can well combine the benefits of both and is ideal for the field of regenerative medicine. In this review, we summarize the various materials and latest technologies to deliver electrical stimulation. The influences of electrical stimulation on cell alignment, migration and its underlying mechanisms are discussed. Then the effect of electrical stimulation on cell proliferation and differentiation are also discussed.

Development of an Efficient and Controllable Nano-porous Copper with Good Wettability and Capillary Performance for Wicks of Vapor Chamber

Chen Sizhen,Cai Han,Li Yahui,Zhang Qi,Sun Yunna,Ding Guifu 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.5

To meet the heat dissipation requirements of microelectronic devices, it is urgent to develop an efficient method to fabricate a controllable micro/nano structure for the wick in vapor chamber, which is widely investigated for its high thermal conductivity and small size. This work proposed a controllable fabrication of nano-porous copper (NPC) with high efficiency, which includes electrodeposition and dealloying. A uniform Cu–Zn alloy with single phase was prepared as the precursor for dealloying through electrodeposition. An innovative solution system for dealloying was developed for the fabrication of the bi-continuous NPC, in which the efficiency was improved ten times compared to the conventional acid solution. In addition, the effects of dealloying parameters on the NPC morphology and the process efficiency have also been studied systematically. Based on the above method, both good wettability and capillary performance were achieved by NPC with tunable pore size, which indicates its great application prospects in wicks for high-performance vapor chamber.