Sandwich Structure Electrode as Advanced Performance Anode for Lithium-Ion Batteries

Wei Chengcheng,Sun Xiaogang,Liang Guodong,Huang Yapan,Hu Hao,Xu Yuhao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.10

In this work, a sandwich structure electrode was prepared by a simple vacuum filtration and rolling process. The SEM showed that the active materials were uniformly embedded in the pores of the three-dimensional conductive network of the carbon nanotube (CNTs) conductive paper. The contact interface area of active material and the conductive network significantly increased and the interface resistance was greatly reduced. The porous anode can accommodate the volume expansion of the silicon and effectively alleviated pressed during cycle. The electrode also exhibited good stability in cycles. Electrochemical tests showed that the first discharge specific capacity of the sandwich electrode reached 2330 mAh/g with a coulombic efficiency of 86%. After 500 cycles, the specific capacity was still maintained at 1512 mAh/g. At a large current density of 2 A/g, the specific capacity hold was 840 mAh/g compared with the copper foil electrode of 100 mAh/g.

Utilizing Structural Equation Modeling and Segmentation Analysis in Real-time Crash Risk Assessment on Freeways

Chengcheng Xu,Dawei Li,Zhibin Li,Wei Wang,Pan Liu 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.7

The study aimed to utilize Structural Equation Modeling (SEM) and K-means clustering for predicting real-time crash risks onfreeways. The SEM was used to transform a number of correlated traffic variables into four independent latent traffic factors, and toestablish the interrelationships among the traffic variables and crash risks. The segmentation analysis based on K-means clusteringwas then conducted to investigate the main traffic factors affecting crash risks in various traffic regimes. It was found that: (a) Themeasurement equations in SEM can effectively account for the correlations among traffic variables by transforming numerouscorrelated traffic variables into several latent traffic variables; (b) The SEM can both capture the direct and indirect effects of trafficflow variables on crash risks. This promotes a better understanding how traffic conditions affect crash risks; (c) The SEM producesmore accurate estimates of crash risks than existing modeling technique. It can increase the crash prediction accuracy by an averageof 7.6% compared with the commonly used logistic regression; and (d) Segmentation analysis results suggested that the trafficfactors contributing to crash risks are various across different traffic regimes. The proactive crash prevention strategies for differenttraffic regimes were discussed based on the findings in the segmentation analysis

Development of a Crash Risk Index to Identify Real Time Crash Risks on Freeways

Chengcheng Xu,Pan Liu,Wei Wang,Xuan Jiang 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.7

The primary objective of this study is to develop a quantitative indicator that can be directly used to identify hazardous traffic states on freeway mainlines. Using data obtained from a 22-mile freeway segment on the I-880N freeway in San Francisco Bay Area in the United States, Fisher discriminant analysis was conducted to derive a linear combination of traffic flow parameters which can be used to distinguish traffic states which may lead to crashes from normal traffic conditions which were potentially safe. A new variable termed “crash risk index” was defined based on the discriminant function. A crash risk index which is smaller than 0 represents a hazardous traffic condition potentially leading to a crash. Accordingly, a crash risk index which is greater than 0 represents normal traffic conditions which, theoretically, will not lead to crash occurrences. The research team tested the prediction performance of using the crash risk index to identify hazardous traffic conditions on freeway mainlines. An overall prediction accuracy of about 65.7% was achieved. Conditional logistic regression analysis was then conducted to evaluate the impacts of crash risk indexes on the likelihood of crash occurrences. It was found that the likelihood of freeway crashes increased with the decreases in crash risk index. One unit decrease in crash risk index increased the risk of crash occurrence by 180.3%. The research team also looked extensively at the impacts of crash risk indexes at different time slices. It was found that the impacts of crash risk index decrease with time and the crash risk index at the time slice most immediately before crashes had the greatest impact on crash occurrences.

Feature of vortex core gyration affected by Dzyaloshinskii-Moriya interaction

Wei Maobin,Hu Yue,Wu Chengcheng,Sui Yingrui,Li Huanan 한국물리학회 2023 Current Applied Physics Vol.46 No.-

The effects of Dzyaloshinskii-Moriya interaction (DMI) on vortex core gyration excited by an out-of-plane polarized current is investigated through micromagnetic simulation. The simulation results demonstrate that the DMI not only widens the current density range for gyration, but also greatly increases the frequency and velocity of gyration. On the premise that DMI is large enough and the vortex configurations can simultaneously be maintained, the stable gyration orbit changes from a circle, to a ring-like and to a bird-nest-like trajectory. Furthermore, by comparing the data of different-size nanodisks, it can be seen that the vortices in smaller and thinner disks can achieve higher velocity and larger amplitude gyration, while in larger and thicker disks, the magnetic vortices can obtain higher oscillation frequency. The conclusions in this research add to the potential applications of magnetic vortex in nano-oscillaors.

Electrochemical Properties of Supercapacitors Using Boron Nitrogen Double-Doped Carbon Nanotubes as Conductive Additive

Hao Hu,Xiaogang Sun,Wei Chen,Jie Wang,Xu Li,Yapan Huang,Chengcheng Wei,Guodong Liang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.7

Carbon nanotubes (CNTs) were doped by ammonium borate as the sources of nitrogen and boron. Under the protection of Ar gas, boron-nitrogen doped CNTs were prepared through nitriding and boronization at high temperature. It is a conductive additive. Then, the obtained CNTs were mixed with activated carbon (AC), SP, sodium dodecyl sulfate (SDS), and cellulose fiber to prepare electrodes. With all the materials, a symmetric electric double-layer supercapacitor (EDLC) was assembled. Next, the materials and electrodes were also characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The factors, chemical connections, and specific surface area of the CNTs were analyzed by X-ray energy spectrum analysis (EDS), X-ray photoelectron spectroscopy (XPS), as well as a specific surface area and porosimetry analyzer (BET). In addition, the electrochemical performances of electric double-layer capacitors were tested with the help of cyclic voltammetry, constant-current charging and discharging, and so on. From the results, we can make a conclusion, that is, both B and N atoms were added into the CNTs and formed bonds successfully with carbon atoms mutually. Besides, the specific surface area is about 1.5 times than that of the CNT. When the charge/discharge current density reaches 50 mA/g, we can find that the mass specific capacitance of the capacitor can run up to 32.19 F/g. Also, we observe that the maximum power density is close to 220 W/kg (700 mA/g), and the energy density can arrive 9.31 Wh/kg (50 mA/g). Based on the impedance test, the electrodes are characterized with low impedance. After 2000 cycles, the boron-nitrogen doped double-layer capacitors maintain a capacitance retention ratio of above 95%. Its power density can still achieve 220 W/kg when the energy density keeps at 3.46 Wh/kg. In other words, the electrochemical performance functions of the electric double-layer capacitors are enhanced while the CNTs serve as the electrodes.

Influences of rubber cushion and bearing position on the mesh characteristics of small-module spiral bevel gear

Maohao Xia,Chaosheng Song,Chengcheng Liang,Siyuan Liu,Zhengminqing Li,Peitang Wei 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.12

A mathematical model of spiral bevel gear with the application of duplex spread blade method was established. A novel finite element model considering the configuration of shafts and bearings was developed. The influences of shafts, bearing position, and rubber cushion on the mesh characteristics of spiral bevel gear under different loads were investigated. Results show that the peak-to-peak value of transmission error and the ratio of contact area and high stress area all increase with the increase in loads. With the existence of rubber cushion, the contact pattern moves to the heel and root sides of the wheel flank, and the peakto-peak value of transmission error and root edge contact area increase. With the front bearing moving from the original position to the positive position, the peak-to-peak value of transmission error increases. With the movement of rear bearing position from negative to positive, the contact pattern moves to the heel and root sides of the wheel flank. The peak-to-peak value of transmission error increases, and the root edge contact area expands.

Stochastic Route Choice Based on VMS Information and Hierarchy for Urban Transport Network

Haoyang Ding,Min Yang,Wei Wang,Chengcheng Xu 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.2

This paper firstly establishes four variational inequalities for stochastic traffic assignment by quantifying information utility of Variable Message Signs (VMS) and hierarchy of transport network. When VMS systems are operated in the higher level of roads such as arterials, the attenuation factor of information utility is integrated with information quantity to define a new formulation of the impact coefficient of VMS on traffic flow, which appears in the definitions of link and path lengths, and allocation parameters. Furthermore, equivalent Variational Inequalities (VIs) of Logit models considering these elements are developed and proved. A case study was conducted using the VI models on a hierarchical road network. We get some practically meaningful results, for example, VMS information can improve hierarchical network performance by interacting with traffic flow in all models except the C-Logit model and hierarchical level can improve network performance. Among the results, the most important is that the C-Logit or pathsize Logit will produce a flow pattern with less fluctuation of traffic densities among links and is less affected by stochastic factors than the multinomial Logit and cross-nested Logit in a stochastic hierarchical road network.

Simulating and Analyzing the Effect on Travel Behavior of Residential Relocation and Corresponding Traffic Demand Management Strategies

Haoyang Ding,Min Yang,Wei Wang,Chengcheng Xu 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.2

Triggered by rapid urban expansion and fast population growth, a progressive residential relocation has occurred in most cities and its impacts on travel behavior have been confirmed in many studies. However, none has evaluated the effects of travel management strategies that relieves the side effects caused by this relocation. To this end, a multi-agent-based simulation model is proposed to assess the impacts of residential relocation on travel behavior and urban transportation in China. Based on the data in Tongling, China, the simulation on six scenarios is conducted to test how the residents in the urban center and suburbs are affected by different strategies, such as increased land diversity in suburbs, lowered growth in private car ownership and improved public transit accessibility. The results indicate that more daily trips would be lengthened and tend to be motorized by this residential relocation. The scenario test shows that compared to other strategies, policies that aims to reduce travel demand and trip distances after residential relocation have a better performance in traffic improvement.

The natural product salicin alleviates osteoarthritis progression by binding to IRE1α and inhibiting endoplasmic reticulum stress through the IRE1α-IκBα-p65 signaling pathway

Zhu Zhenglin,Gao Shengqiang,Chen Cheng,Xu Wei,Xiao Pengcheng,Chen Zhiyu,Du Chengcheng,Chen Bowen,Gao Yan,Wang Chunli,Wang Chunli,Huang Wei 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Despite the high prevalence of osteoarthritis (OA) in older populations, disease-modifying OA drugs (DMOADs) are still lacking. This study was performed to investigate the effects and mechanisms of the small molecular drug salicin (SA) on OA progression. Primary rat chondrocytes were stimulated with TNF-α and treated with or without SA. Inflammatory factors, cartilage matrix degeneration markers, and cell proliferation and apoptosis markers were detected at the mRNA and protein levels. Cell proliferation and apoptosis were evaluated by EdU assays or flow cytometric analysis. RNA sequencing, molecular docking and drug affinity-responsive target stability analyses were used to clarify the mechanisms. The rat OA model was used to evaluate the effect of intra-articular injection of SA on OA progression. We found that SA rescued TNF-α-induced degeneration of the cartilage matrix, inhibition of chondrocyte proliferation, and promotion of chondrocyte apoptosis. Mechanistically, SA directly binds to IRE1α and occupies the IRE1α phosphorylation site, preventing IRE1α phosphorylation and regulating IRE1α-mediated endoplasmic reticulum (ER) stress by IRE1α-IκBα-p65 signaling. Finally, intra-articular injection of SA-loaded lactic-co-glycolic acid (PLGA) ameliorated OA progression by inhibiting IRE1α-mediated ER stress in the OA model. In conclusion, SA alleviates OA by directly binding to the ER stress regulator IRE1α and inhibits IRE1α-mediated ER stress via IRE1α-IκBα-p65 signaling. Topical use of the small molecular drug SA shows potential to modify OA progression.

Structural and photoelectrochemical characterization of TiO2 nanowire/nanotube electrodes by electrochemical etching

Jing Ya,Li An,Zhifeng Liu,Lei E,Wei Zhao,Dan Zhao,Chengcheng Liu 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.6

TiO2 nanowire/nanotube electrodes were synthesized by anodization of titanium foils in ethylene glycol solution containing 0.5 wt% NH4F and 1 wt% water at 60 V for 6 h. The microstructure and morphology of the asprepared electrodes were investigated by XRD and SEM. A possible formation mechanism and oxidation parameters of nanocomposite structure were discussed. The relationship between structural characteristics of TiO2 nanowire/nanotube electrodes and its photoelectrochemical characterization were evaluated by electrochemical analyzer and photocatalytic degradation of methylene blue (MB) solution. Furthermore, these TiO2 nanowire/nanotube electrodes promoted the photoelectrochemical characterization due to the larger surface areas, enhanced light harvesting and electron transport rate. The results show that photocurrent density of 1.44mA/cm2 and photocatalytic degradation of 95.51% was achieved for TiO2 nanowire/nanotube electrodes, which were 0.55mA/cm2 and 20.52% higher than the TiO2 nanotube electrodes under a similar condition, respectively.