Kejia Zhang

Soochow University

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Progress of Inspection and Removal Technology of Thioether

Sichuan Environment (2011)

Kejia Zhang

Thioether compounds were typical odorants in drinking water in China.In this paper the odor characteristics and sources of thioether compounds were introduced.The progress of analysis technologies of thioether compounds such as sensory analysis,instrumental analysis and sensory gas chromatography as well as their advantages,disadvantages and applicability were reviewed.The effects and problems of thioether removal technologies including oxidation,adsorption and combination technology were summarized.

Thioether

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Tunable Negative Differential Resistance and Resistive Switching Properties of Amorphous WOₓ Devices

IEEE Transactions on Electron Devices (2021)

Kejia Zhang Kuan Ren Xizi Qin Shouhui Zhu Feng Yang

The development of multifunctional electric device is of great significance for improving the integration dense of integrated circuits in the future. Herein, amorphous WO _x -based memristor was fabricated and the mechanism of resistance switching was studied in detail. The device exhibited a stable coexistence of bipolar resistive switching (RS) and negative differential resistance (NDR) behaviors at room temperature, which could modulated by changing the annealing time at 300 °C. The optimal high-resistance state (HRS)/low-resistance state (LRS) resistance ratio of ~30 was obtained by postannealing in 100 min. However, both RS and NDR behaviors disappeared with the crystallization of amorphous films when the annealing time was 300 min. The Ohmic conduction mechanism should be responsible for the charge transport of LRS, while the HRS transmission was corporately dominated by the trap-controlled space charge limited conduction (SCLC) and Poole-Frenkel (P-F) emission. The change of trap levels modulated by postannealing was calculated and considered to be the reason for the change of RS and NDR behaviors. Raman spectroscopy provided evidence for the formation of strong W-O bonds, which contributed to the disappearance of RS and NDR behaviors.

Ohmic contact

Memristor

10.1109/ted.2021.3091656

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VETAM-M: A General Model for Voltage-Controlled Memcapacitive-Coupled Memristors

IEEE Transactions on Circuits & Systems II Express Briefs (2021)

Kuan Ren Kejia Zhang Xizi Qin Feng Yang Bai Sun

Memristors and memcapacitors with threshold voltages have a great potential for chaotic circuit design, memory, and neuromorphic systems. Numerous physical experiments have shown the existence of resistance and capacitance coupling changes phenomenon in some voltage-controlled memristors. In this brief, a voltage threshold adaptive memcapacitive-coupled memristor (VTEAM-M) model is proposed to describe the behavior of resistance-capacitance coupling changes and multiple memristive states of voltage-controlled memristors. The core idea of the model is to divide the device into multiple states, each state corresponds to an equivalent dielectric constant function and an equivalent resistivity function, and then use state variables to represent the superposition and transition between states. The VTEAM-M model retaining the accuracy of Voltage ThrEshold Adaptive Memristor (VTEAM) model in resistance simulation, additionally, adds the modeling of multiple memristive states and capacitance changes of devices. The simulation results are in good agreement with the variation of resistance and capacitance with voltage in real devices.

Memristor

Neuromorphic engineering

10.1109/tcsii.2021.3103553

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Citations (14)

Investigation of turbulent flow field in maglev centrifugal blood pumps of CH-VAD and Heartmate III using large-eddy simulation

Research Square (Research Square) (2023)

Peng Wu Wenjing Xiang Kejia Zhang Guanting Du

Abstract Maglev bearings can avoid serious blood damage caused by mechanical bearings, and has become the primary trend of blood pumps. Maglev blood pumps allow a relatively large clearance to improve blood washout and reduce the stress inside the clearance so that blood damage can be reduced. Nonetheless, large clearances also lead to high secondary flow and turbulence intensity, causing further blood damage. This study aims to conduct a thorough analysis of flow fields in two typical maglev blood pumps, the CH-VAD and Heartmate III which feature distinct designs of secondary flow path and impeller (semi-open versus closed impeller) using large eddy simulation (LES) with a focus on the secondary flows and their interaction with the main flows. LES was found to be superior to the Reynolds-averaged Navier-Stokes (RANS) method in predicting performance curves. At high flow rate (8L/min), the efficiency of CH-VAD remains high compared with 5 L/min, while the efficiency of Heartmate III drops considerably. The wide clearance in Heartmate III induced high secondary flow and flow loss, leading to an large incidence angle at both working conditions. The high viscous stress inside the clearances is the major cause of flow loss and potential blood damage in CH-VAD. This study shows that Maglev bearings dose not guarantee good blood compatibility, clearances should be designed based on trade-offs among high shear stress inside smaller clearance, and strong recirculations caused by larger clearances. This study provides useful reference for the design and optimization of maglev blood pumps.

Maglev

10.21203/rs.3.rs-3705271/v1

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Research on Insulation Detection and Fault Location System of Ship Power System

2022 IEEE International Conference on Advances in Electrical Engineering and Computer Applications (AEECA) (2021)

Liu Wei Kejia Zhang Yu Gan Ning Chen

Ship electrical power System is complex and power load is often composed of all kinds of equipment. Accidental power failure often causes severe incidents, significant casualties, devices damage and money loss. Traditional insulation detection includes balanced bridge and differential current detection. Nevertheless there are some problems on traditional methods, including poor reliability, being influenced by capacitance Leakage, small measurement range and low measurement accurate. This article provides a real time online inspection system for ship electrical power, which inspects ground insulation and capacity leakage. Besides, it can also provide faults location, transport data to management platform, set parameters, record alarm data and human machine interacting interface. The insulation detection and fault location system has a high accuracy and well effects.

Leakage (economics)

10.1109/aeeca52519.2021.9574227

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Beneficial Utilization of Rice Husk Ash (RHA) as a New Sorbent for Removal of Antimony (III) from Water

Kejia Zhang Tuqiao Zhang Yang Deng Lei Li Yiping Zhang

Husk

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Electrochemistry‐Driven Interphase Doubly Protects Graphite Cathodes for Ultralong Life and Fast Charge of Dual‐Ion Batteries

ChemSusChem (2023)

Kejia Zhang Decheng Li Jie Shao Yu Jiang Linze Lv

Abstract Dual‐ion batteries (DIBs) with graphite as cathode material, show superiority in terms of sustainability, affordability, and environmental impact over Li‐ion batteries that rely on transition‐metal based cathodes. However, graphite cathodes severely suffer from poor structural stability during anion storage at high potentials because of the co‐intercalation and oxidative decomposition of electrolytes. This work presents an in situ electrochemistry‐driven route to create a bifunctional interphase through implantation of diethylenetriaminepenta(methylene‐phosphonic acid) (DTPMP) on the surface of graphite particles. The reaction mechanisms and functions of DTPMP are investigated both experimentally and theoretically. The DTPMP‐derived interphase not only improves the antioxidative stability of electrolytes but also benefits the desolvation of PF 6 − anions, which doubly protect the graphitic structure and give rise to fast‐charge and ultralong cycling performance of graphite cathodes in DIBs.

Interphase

10.1002/cssc.202300324

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Citations (10)

Numerical simulation of chloride diffusion in cementitious materials by lattice type model

MATEC Web of Conferences (2019)

Tianhua Li Zichao Pan Wenying Bai Kejia Zhang

The chloride ingress is one of the most significant problems to reinforced concrete structures in coastal areas and cold regions where the de-icing salt is commonly used. In this paper, the lattice type model which has been widely used in fracture analysis of brittle materials is applied to simulate the chloride diffusion process in cementitious materials. The theoretical background of the lattice type model in solving the mass transport problem is briefly presented. The analytical solution of the Fick’s law is adopted to theoretically validate the developed lattice type model. After that, two typical case studies are included to demonstrate the application of the lattice type model in the chloride ingress issue. In the first case, the tortuosity effect of the aggregates on the chloride diffusion front at meso-scale is studied by the lattice model. In the second case, the lattice model is applied in the simulation of the chloride diffusion in cracked concrete. The results show that the lattice type model can be a useful tool to simulate the chloride ingress in the cementitious materials.

Lattice (music)

Cementitious

Tortuosity

Lattice diffusion coefficient

10.1051/matecconf/201927502008

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Turbulent flow field in maglev centrifugal blood pumps of CH-VAD and HeartMate III: secondary flow and its effects on pump performance

Biomechanics and Modeling in Mechanobiology (2024)

Peng Wu Kejia Zhang Wenjing Xiang Guanting Du

Maglev

10.1007/s10237-024-01855-1

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The Properties of Flame Sprayed EAA/n-SiO_2 Composite Coatings

China Surface Engineering (2009)

Kejia Zhang

The EAA/n-SiO2 composite coatings were prepared by flame spraying process.The thermal and mechanical properties of composite coatings were tested by differential scanning calorimetry(DSC),thermogravimetric(TG)and electronic tensile testing machine.The furier transform infrared spectroscopy(FTIR)was used to characterize polymer degradation.The experimental results show that the properties of composite coatings were improved greatly by the accretion of nano-SiO2.There are no obvious oxidation or degradation during the processing.The DSC and TG analysis results indicate that n-SiO2 acts as nucleation agents of EAA.The degree of crystallinity for EAA/n-SiO2 composite coatings increase and the crystallization rate increases due to the accretion of nano-SiO2.The favorable properties of the coating were obtained the coating contains 2.0% n-SiO2.The cohesive strength and the adhesive strength to the substrate were 33.87 MPa and 26.30 MPa.The cohesive strength of EAA/n-SiO2 composite coatings improved 30.6% as compared with the pure EAA coating.

Thermogravimetric analysis

Thermal Stability

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