Dielectric Meta-Holograms Enabled with Dual Magnetic Resonances in Visible Light

Li, Zile,Kim, Inki,Zhang, Lei,Mehmood, Muhammad Q.,Anwar, Muhammad S.,Saleem, Murtaza,Lee, Dasol,Nam, Ki Tae,Zhang, Shuang,Luk’yanchuk, Boris,Wang, Yu,Zheng, Guoxing,Rho, Junsuk,Qiu, Cheng-Wei American Chemical Society 2017 ACS NANO Vol.11 No.9

<P>Efficient transmission-type meta-holograms have been demonstrated using high-index dielectric nanostructures based on Huygens principle. It is crucial that the geometry size of building blocks be judiciously optimized individually for spectral overlap of electric and magnetic dipoles. In contrast, reflection-type meta-holograms using the metal/insulator/metal scheme and geometric phase can be readily achieved with high efficiency and small thickness. Here, we demonstrate a general platform for design of dual magnetic resonance based meta-holograms based on the geometric phase using silicon nanostructures that are quarter wavelength thick for visible light. Significantly, the projected holographic image can be unambiguously observed without a receiving screen even under the illumination of natural light. Within the well-developed semiconductor industry, our ultrathin magnetic resonance-based meta-holograms may have promising applications in anticounterfeiting and information security.</P>

Full-space Cloud of Random Points with a Scrambling Metasurface

Li, Zile,Dai, Qi,Mehmood, Muhammad Q.,Hu, Guangwei,yanchuk, Boris Luk’,Tao, Jin,Hao, Chenglong,Kim, Inki,Jeong, Heonyeong,Zheng, Guoxing,Yu, Shaohua,Alù,, Andrea,Rho, Junsuk,Qiu, Cheng-Wei Nature Publishing Group UK 2018 Light, science & applications Vol.7 No.1

<▼1><P>With the rapid progress in computer science, including artificial intelligence, big data and cloud computing, full-space spot generation can be pivotal to many practical applications, such as facial recognition, motion detection, augmented reality, etc. These opportunities may be achieved by using diffractive optical elements (DOEs) or light detection and ranging (LIDAR). However, DOEs suffer from intrinsic limitations, such as demanding depth-controlled fabrication techniques, large thicknesses (more than the wavelength), Lambertian operation only in half space, etc. LIDAR nevertheless relies on complex and bulky scanning systems, which hinders the miniaturization of the spot generator. Here, inspired by a Lambertian scatterer, we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density, functioning in both transmission and reflection spaces. Over 4044 random spots are experimentally observed in the entire space, covering angles at nearly 90°. Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height, a nearly continuous phase coverage, a lightweight, flexible design, and low-heat dissipation. Thus, it may be mass produced by and integrated into existing semiconductor foundry designs. Our work opens important directions for emerging 3D recognition sensors, such as motion sensing, facial recognition, and other applications.</P></▼1><▼2><P><B>Metasurfaces: scrambling light for 3D detection and recognition</B></P><P>Firing light at a manufactured 'metasurface'—one carrying patterns at a smaller scale than the wavelength of the light—fills large volumes of space with defined points of light, potentially improving 3-D recognition and sensor applications. Cheng-Wei Qui and colleagues at the National University of Singapore, with co-workers across Asia and in the USA, created their unique metasurface from amorphous silicon. Light is scattered from and transmitted through the material to generate a cloud of data points in the surrounding space in which the structure and motion of objects under study can be analyzed. The initial development work with this “scrambling metasurface” suggests it could improve pattern recognition, including face recognition, motion detection and augmented reality applications. The researchers describe how their innovation overcomes significant limitations of existing methods in these fields.</P></▼2>

Co–Fe Bimetal Phosphate Composite Loaded on Reduced Graphene Oxide for Oxygen Evolution

Guoxing Zhu,Xulan Xie,Lisong Xiao,Xiaoyun Li,Xiaoping Shen,Yuanjun Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.1

Development of high-performance nonprecious metal-based catalysts for oxygen evolution reaction (OER) is crucial to improve the efficiency of water electrolysis and photoelectrochemical water splitting for harvesting and storage of solar energy. Herein, Co–Fe phosphates and their composites with reduced graphene oxide (rGO) were prepared by a simple hydrothermal method, which then acted as oxygen evolution reaction catalysts. In 1.0 M KOH aqueous solution, the as-obtained optimal composite, Co–Fe phosphate/rGO, can catalyze oxygen evolution reaction with a very sharp onset potential and a small over-potential of 338 mV to achieve a current density of 10 mA cm -2. It was found that in these Co–Fe phosphates, the optimal Co:Fe ratio is 0.75:0.25. The excellent electrocatalytic performance of the Co–Fe phosphate/rGO composite would benefit from the synergistic effects between Fe and Co species, as well as rGO substrate providing conductive channels. The formed Co–Fe phosphate/rGO electrocatalysts can be the promising replacement of precious metal-based catalysts for more practical and cost-efficient water splitting.

Effects of electroslag remelting process and Y on the inclusions and mechanical properties of the CLAM steel

Qiu, Guoxing,Zhan, Dongping,Li, Changsheng,Yang, Yongkun,Jiang, Zhouhua,Zhang, Huishu Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.4

Y-containing CLAM steels were melted via vacuum induction melting and electroslag remelting. In this study, the evolution, microstructure, and mechanical properties of the alloy inclusions (ESR-1 (0 wt.% Y), ESR-2 (0.016 wt.% Y) and ESR-3 (0.042 wt.% Y)) were investigated. Further, the number of inclusions in ESRed steel was observed to obviously decrease, and the distributions were more uniform. The fine Y-Al-O inclusions (1-2 ㎛) were the main inclusions in ESR-2. The addition of Y affected the prior austenite grain size (PAGZ), increasing the tensile strength at test temperature. Low ductile-brittle transition temperature (DBTT) was obtained because of the fine PAGZ and dispersive inclusions. For the ESRed CLAM steel with 0.016 wt.% Y, the yield strengths were 621 MPa at 20 ℃ and 354 MPa at 600 ℃ in air. Further, the uniform elongation and elongation of the ESR-2 alloy were 5.5% and 20.1% at 20 ℃, respectively. Meanwhile, the DBTT tested using full-size Charpy impact specimen (55 cm × 10 cm × 10 cm) was reduced to -83 ℃.

Integrated Path Tracking Control of Steering and Differential Braking Based on Tire Force Distribution

GuodongWang,Li Liu,Yu Meng,Qing Gu,Guoxing Bai 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.2

The integrated path tracking control of steering and differential braking can significantly improve the tracking performance of autonomous vehicles in collision avoidance in the limit conditions. However, the distribution of steering and braking control rights has not received sufficient attention in the existing control method. The distribution strategy is relatively simple and lacks theoretical support. Therefore, aiming at the problem of the distribution of steering and braking control rights in the integrated path tracking control, a tire force distribution rule is proposed in this study, and a path tracking control method based on holistic model predictive control (MPC) is designed. To describe the coupling and strong nonlinearity of tire dynamics, a UniTire tire model with combined slip conditions is established in the controller model. Furthermore, the nonlinear controller model is linearized by Taylor expansion and a linear time-varying MPC controller is designed to improve the real-time performance of the system. Finally, the effectiveness of the proposed method is verified via the co-simulation tests of CarSim and Simulink. The simulation tests at the different speeds and road friction coefficients demonstrate the superiority of the proposed method in path tracking performance, lateral stability, and traffic efficiency.

Static and Seismic Experimental Study of Novel Prefabricated Beam-Column Joints with Elongated-Hole Brackets

Zhang Zhiwei,Li Dong,Wang Huajie,Li Songling,Qian Hongliang,Bi Yanhua,Wang Guoxing,Jin Xiaofei,Fan Feng 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.1

To enhance the structural connectivity of prefabricated steel frame systems and augment their construction effi ciency, this study introduces an innovative prefabricated joint design tailored for square steel columns and H-beams characterized by varying beam heights. This study includes both static loading tests and seismic tests performed on full-scale joints featuring two diff erent beam heights. This investigation involved a comprehensive analysis of the static and seismic performance of the joints, employing various performance metrics such as ultimate load capacities, ultimate rotation angles, hysteresis curves, skeleton curves, stiff ness degradation curves, and ductility coeffi cients, in alignment with established structural codes and standards. The results indicate that the plasticity of the H-beam is fully developed, exhibiting a relative slip phenomenon. Additionally, the joints demonstrate commendable rotational capacity, with hysteresis curves consistently manifesting an inverse S-shape and exhibiting noteworthy stiff ness degradation. Furthermore, the comparison with the unimproved joint shows that the novel joint, in addition to being easy to construct, has better ductility and energy dissipation capacity. The results of the study will provide a technical reference for further optimization and application of prefabricated beam-column joints.

Research on stiffness control of a redundant cable-driven parallel mechanism

Jinshan Yu,Jianguo Tao,Guoxing Wang,Xiao Li,Haowei Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11

Controlling the stiffness of cable-driven parallel mechanisms (CDPM) is of great significance for improving performance in different tasks. A method for stiffness control of a redundant CDPM is presented in this paper. The stiffness matrix of the redundant CDPM is established. On this basis, considering the effect of coupling stiffness, a complete analytical formula for stiffness in different directions is established. Then, the influence of the vector λ on the stiffness of the CDPM in different directions is analyzed, and a method to control the stiffness of the CDPM through adjusting the vector λ is proposed. To avoid traversing the value of λ in the polygon formed by the set of λ to obtain the appropriate cable tension and keep the cable tension away from the upper and lower limit values, a change path of the vector λ is designed. When the vector λ changes along the path, the stiffness of the mechanism can be changed from the minimum value to the maximum value. This method has high computational efficiency and safety. Finally, the correctness and effectiveness of the stiffness control method are verified by experiments. The stiffness control method proposed in this paper can be used to control the stiffness in different directions, and can also be used for different types of redundant CDPMs.

Study on optimal conditions and adsorption kinetics of copper from water by collodion membrane cross-linked poly-γ-glutamic acid

Xiangting Wu,Aiyin Wang,Xiaojie Zheng,Guoxing Li,Xinjiao Dong,Mingjiang Wu 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.6

Poly-γ-glutamic acid (γ-PGA) is a novel polyamino acid formed through microorganism fermentation and biosynthesis. In the present test, membrane (PGA-C) formation by γ-PGA and collodion was performed by using 0.1%glutaraldehyde as a cross-linking agent. A study was conducted on the PGA-C adsorption of Cu2+, specifically the related adsorption equilibrium and kinetics, desorption and regeneration. The results show that with an initial solution pH=5.5and at 318 K, the static adsorption isotherm behavior of PGA-C is in compliance with the Langmuir model and is beneficial to the adsorption of the metal. Meanwhile, with the reaction lasting for 30min, adsorption equilibrium was reached with a maximum adsorption capacity up to 7.431 mg/g. The entire reaction process follows the pseudo-second-order kinetics. By using PGA-C, good regeneration results were obtained after adsorption-generation-adsorption cycling with an HCl solution (0.1 mol/L) as regeneration liquid.

The enhanced photothermal effect of graphene/conjugated polymer composites: photoinduced energy transfer and applications in photocontrolled switches

Meng, Dongli,Yang, Shaojun,Guo, Liang,Li, Guoxing,Ge, Jiechao,Huang, Yong,Bielawski, Christopher W.,Geng, Jianxin The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.92

<P>Composites prepared by grafting poly(3-hexylthiophene) (P3HT) onto the surfaces of reduced graphene oxide (RGO) (RGO-<I>g</I>-P3HT) exhibit an enhanced photothermal effect due to photoinduced energy transfer from P3HT to RGO. A remote photo-controlled electrical switch was prepared using RGO-<I>g</I>-P3HT as a photothermal layer.</P> <P>Graphic Abstract</P><P>Photoinduced energy transfer from a conjugated system to graphene sheets enables the enhanced photothermal effect of graphene-based composites. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc06849a'> </P>