Exceptional electrochemical performance of freestanding electrospun carbon nanofiber anodes containing ultrafine SnO_<i>x</i> particles

Zhang, Biao,Yu, Yang,Huang, Zhendong,He, Yan-Bing,Jang, Donghyuk,Yoon, Won-Sub,Mai, Yiu-Wing,Kang, Feiyu,Kim, Jang-Kyo The Royal Society of Chemistry 2012 ENERGY AND ENVIRONMENTAL SCIENCE Vol.5 No.12

<P>SnO<SUB><I>x</I></SUB>–carbon nanofiber (CNF) composites are synthesized using the electrospinning technique for use as freestanding electrodes in Li-ion batteries. The electrodes made from the composites carbonized at 750 °C (SnO<SUB><I>x</I></SUB>–CNF-750) with 14.5 wt% SnO<SUB><I>x</I></SUB> deliver a remarkable capacity of 674 mA h g<SUP>−1</SUP> after 100 cycles when discharged at 0.5 A g<SUP>−1</SUP>. This result is considered the highest among those reported in the literature for anodes made from similar electrospun carbon fibers containing SnO<SUB><I>x</I></SUB> nanoparticles. An increase in carbonization temperature to 950 °C (SnO<SUB><I>x</I></SUB>–CNF-950) results in a significant reduction of the particle content in the fiber due to aggregation of Sn to form nanoparticles external to the fibers, with concomitant degradation of capacities. The presence of amorphous SnO<SUB><I>x</I></SUB> particles at the atomic scale embedded in the conductive CNFs is thought to be responsible for the exceptional electrochemical performance of the SnO<SUB><I>x</I></SUB>–CNF-750 electrodes. These ultrafine particles facilitate the reaction Sn + <I>x</I>Li<SUB>2</SUB>O → SnO<SUB><I>x</I></SUB> + 2<I>x</I>Li<SUP>+</SUP> + 2<I>x</I>e<SUP>−</SUP>, making it highly reversible, which is confirmed by the growing peak currents with increasing scan rate indicated by cyclic voltammetry, and the absence of Sn–Sn bonds in the particles revealed by the extended X-ray absorption fine structure spectroscopy (EXAFS). Both the SnO<SUB><I>x</I></SUB> particle size and content in the fiber play important roles in controlling the rate and cyclic performance of the SnO<SUB><I>x</I></SUB>–CNF composite electrodes.</P> <P>Graphic Abstract</P><P>This paper presents novel SnO<SUB><I>x</I></SUB>–carbon nanofiber composites with embedded ultrafine SnO<SUB><I>x</I></SUB> particles. The composites deliver remarkable power/energy densities as well as excellent cyclic performance due to their high reversibility and stability. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2ee23145j'> </P>

Introduction of Functionality, Selection of Topology, and Enhancement of Gas Adsorption in Multivariate Metal–Organic Framework-177

Zhang, Yue-Biao,Furukawa, Hiroyasu,Ko, Nakeun,Nie, Weixuan,Park, Hye Jeong,Okajima, Satoshi,Cordova, Kyle E.,Deng, Hexiang,Kim, Jaheon,Yaghi, Omar M. American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.7

<P>Metal-organic framework-177 (MOF-177) is one of the most porous materials whose structure is composed of octahedral Zn4O(-COO)(6) and triangular 1,3,5-benzenetribenzoate (BTB) units to make a three-dimensional extended network based on the qom topology. This topology violates a long-standing thesis where highly symmetric building units are expected to yield highly symmetric networks. In the case of octahedron and triangle combinations, MOFs based on pyrite (pyr) and rutile (rtl) nets were expected instead of qom. In this study, we have made 24 MOF-177 structures with different functional groups on the triangular BTB linker, having one or more functionalities. We find that the position of the functional groups on the BTB unit allows the selection for a specific net (qom, pyr, and rtl), and that mixing of functionalities (-H, -NH2, and -C4H4) is an important strategy for the incorporation of a specific functionality (-NO2) into MOF-177 where otherwise incorporation of such functionality would be difficult. Such mixing of functionalities to make multivariate MOF-177 structures leads to enhancement of hydrogen uptake by 25%.</P>

Eigenvalue Assignment in Linear Descriptor Systems using Dynamic Compensators

Biao Zhang,Jiafeng Zhu 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.5

An approach for eigenvalue assignment in strongly controllable and observable linear descriptor systems using dynamic compensators is proposed. Parametric expressions for the controller coefficient matrices are given. The approach assigns the full number of distinct finite closed-loop eigenvalues, guarantees the closed-loop regularity and overcomes the defects of some previous works. In addition, using the proposed eigenvalue assignment approach, a sufficient condition for generic eigenvalue assignability using dynamic compensators is proved.

Parametric Eigenstructure Assignment for Descriptor Systems via Proportional plus Derivative State Feedback

Biao Zhang 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.1

Eigenstructure assignment for descriptor systems with proportional plus derivative state feedback is studied. Based on a simple complete explicit parametric solution to a group of recursive equations, a parametric approach for eigenstrucure assignment in descriptor systems via proportional plus deriva-tive state feedback is proposed. The proposed approach possesses the following features: 1) it does not impose any condition on the closed-loop eigenvalues, simultaneously assigns arbitrary n finite and infinite eigenvalues to the closed-loop system and guarantees the closed-loop regularity; 2) it is simple and needs less computational work; 3) it gives general complete parametric expressions for the closed-loop eigenvectors, the proportional state feedback gain matrix and the derivative state feedback gain matrix.

Optimized inverse distance weighted interpolation algorithm for γ radiation field reconstruction

Zhang Biao,Cao Jinjia,Lin Shuang,Li Xiaomeng,Zhang Yulong,Zheng Xiaochang,Chen Wei,Song Yingming 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

The inversion of radiation field distribution is of great significance in the decommissioning sites of nuclear facilities. However, the radiation fields often contain multiple mixtures of radionuclides, making the inversion extremely difficult and posing a huge challenge. Many radiation field reconstruction methods, such as Kriging algorithm and neural network, can not solve this problem perfectly. To address this issue, this paper proposes an optimized inverse distance weighted (IDW) interpolation algorithm for reconstructing the gamma radiation field. The algorithm corrects the difference between the experimental and simulated scenarios, and the data is preprocessed with normalization to improve accuracy. The experiment involves setting up gamma radiation fields of three Co-60 radioactive sources and verifying them by using the optimized IDW algorithm. The results show that the mean absolute percentage error (MAPE) of the reconstruction result obtained by using the optimized IDW algorithm is 16.0%, which is significantly better than the results obtained by using the Kriging method. Importantly, the optimized IDW algorithm is suitable for radiation scenarios with multiple radioactive sources, providing an effective method for obtaining radiation field distribution in nuclear facility decommissioning engineering.

Safe Range of Retaining Pressure for Three-dimensional Face of Pressurized Tunnels based on Limit Analysis and Reliability Method

Jiahua Zhang,Wei-jun Wang,Dao-bing Zhang,Biao Zhang,Fei Meng 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.11

Based on the existing research, the 3D active and passive failure mechanisms of a pressurized tunnel face are constructed. The nonlinear failure criterion is introduced into the limit analysis by virtue of the tangent technique. By neglecting the randomness of soil parameters, the collapse pressure of active failure and the blowout pressure of passive failure, namely the lower and upper limit of retaining pressure, are obtained along with the failure ranges. On account of the randomness of soil properties, a three-dimensional stochastic model of a pressurized tunnel face is established, and the optimal range of retaining pressure of the pressurized tunnel face is presented on the basis of the multiple correlated failure modes. Taking Changsha Metro Line 2 as an example, the good agreement of the measured data in situ with the reasonable range of retaining pressure verifies the presented method. The combination of limit analysis and reliability method can provide more scientific and reasonable support parameters for the construction of pressurized tunnels in the future.

Experimental and numerical studies on the behaviour of corroded cold-formed steel columns

Nie Biao,Xu Shanhua,Zhang Haijiang,Zhang Zongxing 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.5

Experimental investigation and finite element analysis of corroded cold-formed steel (CFS) columns are presented. 11 tensile coupon specimens and 6 stub columns of corroded CFS that had a channel section of C160x60x20 were subjected to monotonic tensile tests and axial compression tests, respectively. The degradation laws of the mechanical properties of the tensile coupon specimens and stub columns were analysed. An appropriate finite element model for the corroded CFS columns was proposed and the influence of local corrosion on the stability performance of the columns was studied by finite element analysis. Finally, the axial capacity of the experimental results was compared with the predictions obtained from the existing design specifications. The results indicated that with an increasing average thickness loss ratio, the ultimate strength, elastic modulus and yield strength decreased for the tensile coupon specimens. Local buckling deformation was not noticeable until the load reached about 90% of the ultimate load for the non-corroded columns, while local buckling deformation was observed when the load was only 40% of the ultimate load for the corroded columns. The maximum reduction of the ultimate load and critical buckling load was 57% and 81.7%, respectively, compared to those values for the non-corroded columns. The ultimate load of the columns with web thickness reduced by 2 mm was 53% lower than that of the non-corroded columns, which indicates that web corrosion most significantly affects the bearing capacity of the columns with localized corrosion. The results predicted using the design specifications of MOHURD were more accurate than those predicted using the design specifications of AISI.

Time-optimal and Smooth Trajectory Planning for Robot Manipulators

Tie Zhang,Meihui Zhang,Yan-biao Zou 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.1

This paper presents a practical time-optimal and smooth trajectory planning algorithm and then appliesit to robot manipulators. The proposed algorithm uses the time-optimal theory based on the dynamics model toplan the robot’s motion trajectory, constructs the trajectory optimization model under the constraints of the geometric path and joint torque, and dynamically selects the optimal trajectory parameters during the solving process toprominently improve the robot’s motion speed. Moreover, the proposed algorithm utilizes the input shaping algorithm instead of the jerk constraint in the trajectory optimization model to achieve a smooth trajectory. The inputshaping of trajectory parameters during postprocessing not only suppresses the residual vibration of the robot butalso takes the signal delay caused by traditional input shaping into account. The combination of these algorithmsmakes the proposed time-optimal and smooth trajectory planning algorithm ensure absolute time optimality andachieve a smooth trajectory. The results of an experiment on a six-degree-of-freedom industrial robot indicate thevalidity of the proposed algorithm.

Nonlinear Dust-acoustic Solitary Waves in a Dust Plasma with Two-temperature Nonthermal Ions

Kai-Biao Zhang,Hong-Yan Wang 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.4

The effect of two-temperature nonthermal ions on small, but flnite, amplitude nonlinear dust- acoustic waves (DAW) is studied in a dusty plasma consisting of a negative dust °fluid, Boltzmann distributed electrons, and two-temperature nonthermally distributed ions. We derive a Korteweg-de Vries (KdV) equation governing the dust-acoustic solitary waves by using the reductive perturbation method. We show that the presence of two-temperature nonthermal ions modi¯es the properties of dust-acoustic solitary structures significantly and may allow rarefactive and compressive solitary waves to coexist. The effect of two-temperature nonthermal ions on small, but flnite, amplitude nonlinear dust- acoustic waves (DAW) is studied in a dusty plasma consisting of a negative dust °fluid, Boltzmann distributed electrons, and two-temperature nonthermally distributed ions. We derive a Korteweg-de Vries (KdV) equation governing the dust-acoustic solitary waves by using the reductive perturbation method. We show that the presence of two-temperature nonthermal ions modi¯es the properties of dust-acoustic solitary structures significantly and may allow rarefactive and compressive solitary waves to coexist.

Structural health monitoring of a newly built high-piled wharf in a harbor with fiber Bragg grating sensor technology: design and deployment

Liu, Hong-biao,Zhang, Qiang,Zhang, Bao-hua Techno-Press 2017 Smart Structures and Systems, An International Jou Vol.20 No.2

Structural health monitoring (SHM) of civil infrastructure using fiber Bragg grating sensor networks (FBGSNs) has received significant public attention in recent years. However, there is currently little research on the health-monitoring technology of high-piled wharfs in coastal ports using the fiber Bragg grating (FBG) sensor technique. The benefits of FBG sensors are their small size, light weight, lack of conductivity, resistance corrosion, multiplexing ability and immunity to electromagnetic interference. Based on the properties of high-piled wharfs in coastal ports and servicing seawater environment and the benefits of FBG sensors, the SHM system for a high-piled wharf in the Tianjin Port of China is devised and deployed partly using the FBG sensor technique. In addition, the health-monitoring parameters are proposed. The system can monitor the structural mechanical properties and durability, which provides a state-of-the-art mean to monitor the health conditions of the wharf and display the monitored data with the BIM technique. In total, 289 FBG stain sensors, 87 FBG temperature sensors, 20 FBG obliquity sensors, 16 FBG pressure sensors, 8 FBG acceleration sensors and 4 anode ladders are installed in the components of the back platform and front platform. After the installation of some components in the wharf construction site, the good signal that each sensor measures demonstrates the suitability of the sensor setup methods, and it is proper for the full-scale, continuous, autonomous SHM deployment for the high-piled wharf in the costal port. The South 27# Wharf SHM system constitutes the largest deployment of FBG sensors for wharf structures in costal ports to date. This deployment demonstrates the strong potential of FBGSNs to monitor the health of large-scale coastal wharf structures. This study can provide a reference to the long-term health-monitoring system deployment for high-piled wharf structures in coastal ports.