Joint Deployment and Trajectory Optimization in UAV-Assisted Vehicular Edge Computing Networks

Zhiwei Wu,Zilin Yang,Chao Yang,Jixu Lin,Yi Liu,Xin Chen 한국통신학회 2022 Journal of communications and networks Vol.24 No.1

As the general mobile edge computing (MEC)scheme cannot adequately handle the emergency communicationrequirements in vehicular networks, unmanned aerial vehicle(UAV)-assisted vehicular edge computing networks (VECNs) areenvisioned as the reliable and cost-efficient paradigm for themobility and flexibility of UAVs. UAVs can perform as thetemporary base stations to provide edge services for road vehicleswith heavy traffic. However, it takes a long time and huge energyconsumption for the UAV to fly from the stay charging stationto the mission areas disorderly. In this paper, we design a predispatchUAV-assisted VECNs system to cope with the demandof vehicles in multiple traffic jams. We propose an optimalUAV flight trajectory algorithm based on the traffic situationawareness. The cloud computing center (CCC) server predictsthe real-time traffic conditions, and assigns UAVs to differentmission areas periodically. Then, a flight trajectory optimizationproblem is formulated to minimize the cost of UAVs, while boththe UAV flying and turning energy costs are mainly considered. Inaddition, we propose a deep reinforcement learning(DRL)-basedenergy efficiency autonomous deployment strategy, to obtain theoptimal hovering position of UAV at each assigned mission area. Simulation results demonstrate that our proposed method canobtain an optimal flight path and deployment of UAV with lowerenergy consumption.

A novel UiO-66-NH2/graphene oxide composite thin membrane for retarding membrane wetting in membrane distillation

Fangqing Li,Lin Chen,Yufei Wei,Zhiwei Yin,Keying Que 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.123 No.-

Membrane distillation (MD) is considered an emerging desalination technology. However, the presenceof surfactants allows liquid to penetrate the membrane, resulting in membrane wetting, which hindersthe commercialization of MD. In this study, we use very few modified materials to prepare novel Janusthin membranes that immobilize modified materials (graphene oxide (GO) and UiO-66-NH2) on polytetrafluoroethylene(PTFE) hydrophobic base membranes via crosslinkers. The composite thin membraneproperties with eight different ratios and contents of GO and UiO-66-NH2 were fabricated and testedby a feed solution of sodium chloride containing a high concentration of sodium dodecyl sulfate. An optimalratio of Janus membrane with high flux without affecting the effluent water quality was obtained. The Janus membrane exhibited excellent anti-wetting properties compared to the original PTFE membrane. A desalination rate of up to 99.9% was still available even under 48 h of long-term operating conditionsby maintaining a flux of approximately 21.2 L/(m2h). The anti-wetting mechanism of thismembrane was further confirmed by the modified XDLVO model. It suggested that the novel Janus membranecould be a highly promising substitute to the MD process for the resource-based treatment ofsurfactant-containing wastewater, which played an important role in promoting its application.

SRRS Effects on ICF Laser Drive Beam with the Variation of Pump Light Distribution on Space

Ying Liu,Dianyang Lin,Zhiwei Lu,Weiliang Zeng 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.6

Tens to hundreds of output high power lasers from ICF (inertial confinement fusion) device, generally need to propagate through a long air path before they reach the target chamber. During the process, interaction between the high power pulse laser and air molecules emerges. Once the SRRS (stimulated rotational Raman scattering) threshold was reached, the SRRS effect would result in the loss of laser energy, the decrease of laser beam quality, or unable to reach the target. Further the transmitted laser would enter the multipliers as fundamental beam, then the conversion efficiency of triple-harmonic would be affected, even cause the destroy of frequency multiplication crystal. In order to improve the output ability, beam quality and control ability of the ICF high power laser drive, ultimately achieve the fusion ignition success, the SRRS effect must be suppressed. Based on SRRS four-dimensional mathematical model which conforms to current ICF experiment conditions, the longitudinal and horizontal rules of SRRS effect on ICF laser drive beam with the variation of pump light distribution on space was obtained. The research provided a support for the parameters choice of ICF laser drive and the optimization of output beam quality.

Recombinant human β-defensin130 inhibited the growth of foodborne bacteria through membrane disruption and exerted anti-inflammatory activity

Bin Dong,Yanjun Lin,Zhiwei Su,Chunlong Sun,Jun Wang,Shijun Fu,Wen Du,Tao Wu 한국식품과학회 2022 Food Science and Biotechnology Vol.31 No.7

Foodborne pathogens causing food poisoning and infections are detrimental to human health, and the abuse of antibiotics induced severe antibiotic resistance in past decades. Thus, it is urgent to develop new antimicrobial agents. In the current study, human β-defensin 130 (hBD130), which is an antimicrobial peptide identified in human macrophages in 2017, was initially produced in Pichia pastoris. The purified hBD130 demonstrated broad bactericidal spectrum against foodborne pathogens through a membrane disruption, with concentrations ranging from 10 to 45 μg/mL. Moreover, hBD130 showed a low hemolytic effect and nearly no cytotoxicity to mammalian cells with a dosage of 400 μg/mL. In addition, the secretion amounts and mRNA levels of NO, IL-6, IL-1β, and TNF-α in LPS-induced mouse macrophage were significantly decreased with 1 mg/mL of hBD130. Taken together, these results showed that hBD130 is a promising antimicrobial agent to treat foodborne bacterial infections and inflammation.

Ternary Phase Diagram-Facilitated Rapid Screening of Double Perovskites As Electrocatalysts for the Oxygen Evolution Reaction

Sun, Hainan,Hu, Zhiwei,Xu, Xiaomin,He, Juan,Dai, Jie,Lin, Hong-Ji,Chan, Ting-Shan,Chen, Chien-Te,Tjeng, Liu Hao,Zhou, Wei,Shao, Zongping American Chemical Society 2019 Chemistry of materials Vol.31 No.15

<P>The development of cost-effective, non-noble metal electrocatalysts for the oxygen evolution reaction (OER) is of paramount importance for sustainable technologies. Efficient screening strategies for electrocatalysts can greatly increase the commercialization speed of these advanced technologies. Here, ternary phase diagrams with large-scale tuning and designated-scale tuning strategies are applied for the first time to provide a new method for screening perovskite oxide-based electrocatalysts for OERs. Specifically, the family of double perovskites (Sr<SUB>2</SUB>Fe<SUB>1.5-<I>x</I>-<I>y</I></SUB>Co<SUB><I>x</I></SUB>Ni<SUB><I>y</I></SUB>Mo<SUB>0.5</SUB>O<SUB>6−δ</SUB>, 0 ≤ <I>x</I>, <I>y</I> ≤ 1.5) was utilized to understand the role of transition metals in perovskite oxides. Ternary phase diagrams can facilitate a rapid screening process, provide a straightforward relationship between phase structures and catalytic activities, and help to confirm the effects of various combinations of transition metals on the OER activity. The Fe-Co system (Sr<SUB>2</SUB>Fe<SUB>1.5-<I>x</I></SUB>Co<SUB><I>x</I></SUB>Mo<SUB>0.5</SUB>O<SUB>6−δ</SUB>) improves the catalytic activities, as demonstrated by the reduced Tafel slope and enhanced stability, while the Fe-Ni system (Sr<SUB>2</SUB>Fe<SUB>1.5-<I>y</I></SUB>Ni<SUB><I>y</I></SUB>Mo<SUB>0.5</SUB>O<SUB>6−δ</SUB>) improves the surface kinetic properties of the OER, as demonstrated by its reduced overpotential. Significantly, the Co, Ni, and Fe ternary phase systems can serve as the synergistic coactive sites (Sr<SUB>2</SUB>Fe<SUB>1.5-<I>x</I>-<I>y</I></SUB>Co<SUB><I>x</I></SUB>Ni<SUB><I>y</I></SUB>Mo<SUB>0.5</SUB>O<SUB>6−δ</SUB>) to catalyze the OER, resulting in an improved overall OER performance. This systematic study not only demonstrates a new strategy to allow the rapid screening of double perovskite OER catalysts based on large-scale tuning and designated-scale tuning strategies but, more importantly, also provides an insightful understanding of the use of multitransition metal-based double perovskites for catalysis of the OER.</P> [FIG OMISSION]</BR>

Closed T-Spline Surface Reconstruction from Medical Image Data

Ce Shang,Jianzhong Fu,Zhiwei Lin,Jiawei Feng,Bin Li 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.11

The reconstruction from medical image data to CAD model is an essential process of Bio-medical engineering. So far, it is still challenging to create medical model which is suitable for both design and manufacturing. This paper introduces a process of constructing a single-patched closed T-spline surface model based on medical image data. The image data is first converted into triangular mesh and then parameterized onto a rectangular domain. An iterative least-squares fitting process is proposed to finally obtain the T-spline surface model with a user-specified tolerance. In this fitting process, the smoothing part of the algorithm is redesigned, considering the flexible structure of T-mesh and the geometric complexity of the T-spline surface. Local smoothness weighting factors are introduced to the fitting formula to locally adjust the smoothness of the surface. An adaptive smoothness checking points distribution method is proposed to reduce the computational cost. These algorithms are easy to implement and the obtained model is simple in form. Compared with the STL and NURBS model, the T-spline surface model requires less storage space and can be easily modified. The obtained model is suitable for Bio-medical engineering applications like bone scaffolds design, surgical planning and related manufacturing process.

Study on mass transfer and heat transfer in transition zone of short-path distillation separation equipment based on N-dodecanol and N-hexadecanol

Zhenya Duan,Haodong Zhang,Bin Liu,Zhiwei Sun,Junmei Zhang,Longlong Lin 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2

Based on the fact that the distance between the heat exchange surfaces has little influence on the separation efficiency in the short-path distillation, a hypothesis that the heat and mass transfer process in the transition region is controlled by heat convection is proposed; the gas-liquid state in the transition zone was calculated by numerical simulation experiment. The results show that the gas-liquid volume fraction and temperature fluctuation in the evaporation and condensation process is unstable, while the gas-liquid volume fraction and temperature fluctuation in the transition zone is stable in the short-path distillation process. It can be concluded that in unsteady thermodynamics, the transition zone is a stable convective heat transfer process that is not affected by the distance between heat transfer surfaces. Thus, under ideal conditions, the continuous extension of the transition region has little effect on the distillation efficiency.

Improvement of the Beam-Wave Interaction Eciency Based on the Coupling-Slot Configuration in an Extended Interaction Oscillator

Sairong Zhu,Yong Yin,Liangjie Bi,Zhiwei Chang,Che Xu,Fanbo Zeng,Ruibin Peng,Wen Zhou,Bin Wang,Hailong Li,Lin Meng 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.9

A method aimed at improving the beam-wave interaction eciency by changing the coupling slot configuration has been proposed in the study of extended interaction oscillators (EIOs). The disper- sion characteristics, coupling coecient and interaction impedance of the high-frequency structure based on different types of coupling slots have been investigated. Four types of coupled cavity structures with different layouts of the coupling slots have been compared to improve the beam- wave interaction eciency, so as to analyze the beam-wave interaction and practical applications. In order to determine the improvement of the coupling slot to a coupled cavity circuit in an EIO, we designed four nine-gap EIOs based on the coupled cavity structure with different coupling slot configurations. With different operating frequencies and voltages takes into consideration, beam voltages from 27 to 33 kV have been simulated to achieve the best beam-wave interaction eciency so that the EIOs are able to work in the 2 mode. The in uence of the Rb and the ds on the output power is also taken into consideration. The Rb is the radius of the electron beam, and the ds is the width of the coupling slot. The simulation results indicate that a single-slot-type EIO has the best beam-wave interaction eciency. Its maximum output power is 2.8 kW and the eciency is 18% when the operating voltage is 31 kV and electric current is 0.5 A. The output powers of these four EIOs that were designed for comparison are not less than 1.7 kW. The improved coupling-slot con- gurations enables the extended interaction oscillator to meet the different engineering requirements better.

Boosting the oxygen evolution reaction activity of a perovskite through introducing multi-element synergy and building an ordered structure

Sun, Hainan,Xu, Xiaomin,Hu, Zhiwei,Tjeng, Liu Hao,Zhao, Jie,Zhang, Qin,Lin, Hong-Ji,Chen, Chien-Te,Chan, Ting-Shan,Zhou, Wei,Shao, Zongping The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.16

<P>If different active sites in a catalyst have optimal binding to different reaction intermediates and short reaction paths among them, they may work cooperatively to enhance the oxygen evolution reaction (OER) activity. Based on this design principle, in this study, we start with a B-site ordered double perovskite Sr2FeMoO6−δ with poor OER activity as the host material to fulfill the requirement of a short pathway, and then, replace Mo with Ni and Fe with Co to optimize the synergistic interplay of the multi-active sites. Replacing Mo with Ni indeed dramatically enhances the OER activity and structural/operating stability. Further improvement in OER performance is realized by partial substitution of Fe with Co, leading to the development of a material with the nominal composition of Sr2Fe0.8Co0.2Mo0.65Ni0.35O6−δ, which outperforms the noble metal oxide IrO2 and is better than most of the electrocatalysts developed based on a single descriptor, such as Ba0.5Sr0.5Co0.8Fe0.2O3−δ (eg occupancy close to unity), PrBaCo2O5+δ (O 2p-band center relative to the Fermi level), and La0.5Sr0.5CoO3−δ (charge-transfer energy) in many aspects. As a universal method, combined structural and compositional tuning to create a cooperative effect among different active sites for intermediate adsorption and reaction in an ordered structure may provide a new way for the design of superior electrocatalysts for various applications.</P>

Anatomical Adaptations of the Xerophilous Medicinal Plant, Capparis spinosa, to Drought Conditions

Lu Gan,Chunyu Zhang,Yongtai Yin,Zhiwei Lin,Yongwei Huang,Jun Xiang,Chunhua Fu,Maoteng Li 한국원예학회 2013 Horticulture, Environment, and Biotechnology Vol.54 No.2

Capparis spinosa is a plant that grows in dry and arid environments. As far as can be ascertained, no comprehensive studies on how the leaf, stem and root structures adapt to drought conditions have been published to date. In this paper, a study into the anatomical adaptations of the leaf, stem and root of C. spinosa to drought environments was conducted using in vitro cultured seedlings as control. The results showed that C. spinosa could change its leaf, stem, and root structures when adapting to drought conditions. The plant growing under drought conditions possessed an enlarged transit region between the stem and root where the xylem and fibro-vascular system had increased in order to enhance water absorption and storage capacity. The leaf, stem and root of C. spinosa under drought conditions were better developed than those under normal in vitro culture conditions. The leaf possessed uniform mesophyll cells and three or four layers of palisade mesophyll cells on both sides of the mature leaves. The stomata were evenly distributed across both sides of the leaf, and they remained open continually during the day throughout the summer growing period, especially those on the lower leaf surface. The xylem in the stem was extremely well developed with wide vessels and much thicker cortical layers. All these characteristics can enhance the adaptability of C. spinosa and enable it to survive in extremely dry and arid areas.