Broadband Spectrum Sensing of Distributed Modulated Wideband Converter Based on Markov Random Field

Zhi Li,Jiawei Zhu,Ziyong Xu,Wei Hua 한국전자통신연구원 2018 ETRI Journal Vol.40 No.2

The Distributed Modulated Wideband Converter (DMWC) is a networking system developed from the Modulated Wideband Converter, which converts all sampling channels into sensing nodes with number variables to implement signal undersampling. When the number of sparse subbands changes, the number of nodes can be adjusted flexibly to improve the reconstruction rate. Owing to the different attenuations of distributed nodes in different locations, it is worthwhile to find out how to select the optimal sensing node as the sampling channel. This paper proposes the spectrum sensing of DMWC based on a Markov random field (MRF) to select the ideal node, which is compared to the image edge segmentation. The attenuation of the candidate nodes is estimated based on the attenuation of the neighboring nodes that have participated in the DMWC system. Theoretical analysis and numerical simulations show that neighboring attenuation plays an important role in determining the node selection, and selecting the node using MRF can avoid serious transmission attenuation. Furthermore, DMWC can greatly improve recovery performance by using a Markov random field compared with random selection.

An Offloading Strategy for Multi-User Energy Consumption Optimization in Multi-MEC Scene

( Zhi Li ),( Qi Zhu ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.10

Mobile edge computing (MEC) is capable of providing services to smart devices nearby through radio access networks and thus improving service experience of users. In this paper, an offloading strategy for the joint optimization of computing and communication resources in multi-user and multi-MEC overlapping scene was proposed. In addition, under the condition that wireless transmission resources and MEC computing resources were limited and task completion delay was within the maximum tolerance time, the optimization problem of minimizing energy consumption of all users was created, which was then further divided into two subproblems, i.e. offloading strategy and resource allocation. These two subproblems were then solved by the game theory and Lagrangian function to obtain the optimal task offloading strategy and resource allocation plan, and the Nash equilibrium of user offloading strategy games and convex optimization of resource allocation were proved. The simulation results showed that the proposed algorithm could effectively reduce the energy consumption of users.

Cement Embolus Trapped in the Inferior Vena Cava Filter during Percutaneous Vertebroplasty

Zhi Li,Rui-fang Ni,Xin Zhao,Chao Yang,Ming-ming Li 대한영상의학회 2013 Korean Journal of Radiology Vol.14 No.3

A 58-year-old female patient, diagnosed with adenocarcinoma of the lung, underwent percutaneous vertebroplasty at the L4 vertebral body due to painful spinal metastases. Because of deep venous thrombosis of the left femoral and iliac veins, an inferior vena cava filter had been placed before vertebroplasty. Bone cement migrated into the venous bloodstream and then was being trapped within the previously placed filter. This case illustrates that caval filter could capture the bone cement and prevent it from migrating to the pulmonary circulation.

Electrostatic Field Calculation and Structure Optimization of New Shield Ring of 1000 kV Nan-Jing Loop Transmission Line

Zhi Li,Zhang Yujiao,Xiang Guanteng,Yuan Jiansheng,Jiang Lan 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.3

Considering the frequent breakage of the hard jumper shield ring in the strain tower of ultra-high voltage alternating current 1000 kV Nan-Jing Transmission Line, the theoretical and experimental studies on new shield ring were carried out in terms of mechanical properties; however, due to the structural changes of shield ring, the fi eld characteristics should be calculated and analyzed. In accordance with the theory that there is no electric field in a metal conductor under electrostatic equilibrium, if there is any metal conductor in the 3D model of the computational domain, there will be no need to subdivide the metal conductor. In this paper, a 3D model load applying method with metal conductors was proposed to calculate the field intensity of Tuned mass damper (TMD) shield ring after improving the mechanical properties of the strain tower, which saved the total number of mesh subdivisions by 48.02%, reduced the computational time by 76.47%, and increased the computational effi ciency of 3D numerical electric field. The calculation results validated the correctness and effectiveness of this method. The new TMD shield ring with the field intensity meeting the relevant requirements was adopted in 1000 kV Nan-Jing Loop Transmission Line in December 2016, which has been operating in good condition so far.

Comparative analysis of physiological traits of three Actinidia valvata Dunn genotypes during waterlogging and post-waterlogging recovery

Zhi Li,Yunpeng Zhong,Danfeng Bai,Miaomiao Lin,Xiujuan Qi,Jinbao Fang 한국원예학회 2020 Horticulture, Environment, and Biotechnology Vol.61 No.5

Kiwifruit ( Actinidia sp.) vines are poorly adapted to waterlogging stress. Actinidia valvata is more tolerant against waterloggingstress than Actinidia deliciosa , and the latter contains some common rootstocks that are frequently used in kiwifruit cultivation. Little is known about the responses of A. valvata genotypes against waterlogging stress and during post-waterloggingrecovery. Here, we compared physiological traits of three A. valvata genotypes (KR1, KR3, and KR5) during waterloggingstress and recovery. Kiwifruit vines displayed water loss, a decline in the net photosynthetic rate, and inhibited shoot elongationduring waterlogging. These three genotypes could endure long-term waterlogging owing to their unique root systemconfi gurations as well as by sustaining carbohydrate reserves in the roots. Feeder roots of KR1 vines were damaged earlierand lost water more quickly than the other genotypes. Under the same stress, KR3 formed adventitious roots more rapidly,while KR5 had an improved ability to control water loss in above-ground tissues. After reoxygenation, growth of vineswas partially recovered due to water loss control, photosynthetic recovery, and carbohydrate replenishment. KR3 and KR5recovered their growth earlier and replenished more carbohydrates than KR1 after re-aeration. During waterlogging, both therelative water content and carbohydrate levels of vines can limit the recovery effi ciency after re-aeration. Our results revealedmutual and distinct responses of diff erent A. valvata genotypes during waterlogging stress and recovery and provided moreinsight into the physiological basis of their adaptation to waterlogging stress.

Sustainable Development of Diversified Teaching Mode from Ecological Perspective: A Case Study on Metaverse- Based Landscape Oil Painting Course

Zhi Li,Xiao Chen 한국멀티미디어학회 2023 The journal of multimedia information system Vol.10 No.3

Art can purify the soul and cultivate sentiment. Artists promote the dissemination and popularization of ecological awareness through the power of art. Painting has a strong visual aesthetic ideology and closely relates to people, nature, and society. Landscape oil paintings use vis-ual metaphor and symbolic expression techniques to endow paintings with multiple and rich ecological concepts, conveying anxiety about various ecological imbalances in human society. However, the exploration of oil painting teaching has stopped in universities recently. There-fore, it is necessary to study the diversified landscape oil painting teaching mode from the perspective of ecology to promote its sustainable development. To further immerse students in nature and advance the sustainable development of oil painting teaching from an ecological per-spective, teachers can utilize VR to create natural scenery by introducing the metaverse into the landscape oil painting course. However, in the 360-degree VR landscape sampling video, if the texture cannot be processed well, the student's experience will be significantly reduced. To this end, the texture synthesis of VR videos is studied. The simulation results show that the proposed texture synthesis method performs better in time and space, which undoubtedly improves the students' experience of watching VR landscape videos. Finally, this study uses question-naires to examine the application effect of metaverse-based landscape oil painting courses. The experimental results demonstrate that metaverse-based landscape oil painting courses can increase students' sense of immersion, most strikingly, which is of great help to the im-provement of grades.

Influence of a community of buildings on tornadic wind fields

Zhi Li,Ryan Honerkamp,Gui-rong Yan,Ruoqiang Feng 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.2

To determine tornadic wind loads, the wind pressure, forces and moments induced by tornadoes on civil structures have been studied. However, in most previous studies, only the individual building of interest was included in the wind field, which may be suitable to simulate the case where a tornado strikes rural areas. The statistical data has indicated that tornadoes induce more significant fatalities and property loss when they attack densely populated areas. To simulate this case, all buildings in the community of interest should be included in the wind field. However, this has been rarely studied. To bridge this research gap, this study will systematically investigate the influence of a community of buildings on tornadic wind fields by modeling all buildings in the community into the wind field (designated as “the Community case under tornadic winds”). For comparison, the case in which only a single building is included in the tornadic wind field (designated as “the Single-building case under tornadic winds”) and the case where a community of buildings are included in the equivalent straight-line wind field (designated as “the Community case under straight-line winds”) are also simulated. The results demonstrate that the presence of a number of buildings completely destroys the pattern of regular circular strips in the distribution of tangential velocity and pressure on horizontal planes. Above the roof height, the maximum tangential velocity is lower in the Community case under tornadic winds than that in the Single-building case under tornadic winds because of the higher surface friction in the Community case; below the roof height, greater tangential velocity and pressure are observed in the Community case under tornadic wind fields, and more unfavorable conditions are observed in the Community case under tornadic winds than under the equivalent straight-line winds.

Dynamic modeling and control of industrial crude terephthalic acid hydropurification process

Zhi Li,Weimin Zhong,Yang Liu,Na Luo,Feng Qian 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.4

Purified terephthalic acid (PTA) is critical to the development of the polyester industry. PTA productionconsists of p-xylene oxidation reaction and crude terephthalic acid (CTA) hydropurification. The hydropurificationprocess is necessary to eliminate 4-carboxybenzaldehyde (4-CBA), which is a harmful byproduct of the oxidation reactionprocess. Based on the dynamic model of the hydropurification process, two control systems are studied usingAspen Dynamics. The first system is the ratio control system, in which the mass flows of CTA and deionized water arecontrolled. The second system is the multivariable predictive control-proportional-integral-derivative cascade controlstrategy, in which the concentrations of 4-CBA and carbon monoxide are chosen as control variables and the reactiontemperature and hydrogen flow are selected as manipulated variables. A detailed dynamic behavior is investigatedthrough simulation. Results show that the developed control strategies exhibit good control performances, thereby providingtheoretical guidance for advanced control of industry-scale PTA production.

Inhibition of HBV replication and gene expression in vitro and in vivo with a single AAV vector delivering two shRNA molecules

( Zhi Li ),( Ming Liang He ),( Hong Yao ),( Qing Ming Dong ),( Yang Chao Chen ),( Chu Yan Chan ),( Bo Jian Zheng ),( Kwok Yung Yuen ),( Ying Peng ),( Qiang Sun ),( Xiao Yang ),( Marie C. Lin ),( Josep 생화학분자생물학회 2009 BMB Reports Vol.42 No.1

Quantifying the Impacts of Land Use Change on Soil Water Movement using Environmental Tracerson the Loess Tableland of China

Zhi Li,Xi Chen 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6