Cross-Layer Resource Allocation Scheme for WLANs with Multipacket Reception

Lei Xu,Dazhuan Xu,Xiaofei Zhang,Shufang Xu 한국전자통신연구원 2011 ETRI Journal Vol.33 No.2

Tailored for wireless local area networks, the present paper proposes a cross-layer resource allocation scheme for multiple-input multiple-output orthogonal frequency-division multiplexing systems. Our cross-layer resource allocation scheme consists of three stages. Firstly, the condition of sharing the subchannel by more than one user is studied. Secondly, the subchannel allocation policy which depends on the data packets’ lengths and the admissible combination of users per subchannel is proposed. Finally, the bits and corresponding power are allocated to users based on a greedy algorithm and the data packets’ lengths. The analysis and simulation results demonstrate that our proposed scheme not only achieves significant improvement in system throughput and average packet delay compared with conventional schemes but also has low computational complexity.

Numerical Analysis on Mechanical Property of Concrete Filled Steel Tube Reinforced Concrete (CFSTRC) Columns Subjected to ISO-834 Standard Fire

Lei Xu,Lei Xu,Wen-Da Wang,Jian-Gang Sun 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4

The present study established a numerical investigation on the behavior of concrete filled steel tube reinforced concrete (CFSTRC) columns subjected to fire. A finite element analysis (FEA) model was built to simulate the performance of CFSTRC columns under combined loading and fire. The FEA model was verified by the experimental results of CFSTRC columns subjected to fire. The comparison demonstrated an acceptable accuracy for the proposed FEA model. Afterwards, the FEA model was used to analyze the failure modes, the redistribution of internal force, the changes and development of the stress and strain, and the contact stress between the tube and concrete of CFSTRC columns subjected to fire. Influencing factors that may affect the bearing capacity of the CFSTRC columns subjected to fire were analyzed. The bearing capacity and stiffness of the CFSTRC columns gradually decreased in the fire; the parameters such as the fire duration time, sectional dimension, slenderness ratio, and sectional core area ratio significantly influenced the bearing capacity of the CFSTRC columns. Finally, a simplified calculating formula was proposed to calculate the influence factors of the bearing capacity of the CFSTRC columns subjected to ISO-834 standard fire. The formula-calculated results were well in agreement with the finite element analysis results, which provide a simple and feasible method for evaluating the fire-resistance design of these types of components in practical engineering.

A metal oxide TFT gate driver with a single negative power source employing a boosting module

Yangang Xu,Jun-Wei Chen,Wen-Xing Xu,Lei Zhou,Wei-Jing Wu,Jianhua Zou,Miao Xu,Lei Wang,Junbiao Peng 한국정보디스플레이학회 2020 Journal of information display Vol.21 No.1

This paper presents a new gate driver integrated by In-Zn-O thin-film transistors (IZO TFTs) with the etch stop layer (ESL) structure, in which only a single negative power source is used on account of a new boosting module. The boosting module is controlled only by the VIN signal for generating a lower level than VSS. The proposed gate driver with 15 stages is fabricated through the IZO TFT process on a glass substrate to verify its function. The experiment results showed that the proposed gate driver can successfully output full-swing waveforms with resistive load RL=2 kΩ and capacitive load CL=30 pF at the 16.7 and 66.7 kHz clock frequencies, and can also output as small as 3.2 μs pulse width with little distortion, revealing good stability.

Uniform Side Illumination Generated from LEDs Arranged by an Annealing Algorithm

Xu Wang,Panling Lei,Chaoyi Qian,Zhiping Wang,Xuefen Xu,Zhouping Su 한국광학회 2022 Current Optics and Photonics Vol.6 No.3

Given a cubic space, it is easy to uniformly illuminate the floor with light sources placed on top. However, little has been reported about uniform illumination on walls with the same configuration of light sources. Here we present a luminaire consisting of nine light-emitting diodes (LEDs) with perfect Lambertian distribution, placed on the top as a 3 × 3 rectangular LED array. The distances between LEDs and tilt angles of each individual LED are adjustable and optimized by an annealing algorithm. After optimization, the array produces a rectangular illumination pattern on one wall with a uniformity of about 89%. Analysis shows that the tilt angles of individual LEDs are key parameters for uniform side illumination. In a scenario that is more practical, the tilt angles of all the LEDs are set to be the same, only decreasing the uniformity to 83%.

Wave propagation of graphene platelets reinforced metal foams circular plates

Lei-Lei Gan,Jia-Qin Xu,Gui-Lin She 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.5

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity- I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.

Design of Distance Measuring System Based on MEMS Accelerometer

Lei Xu,Liqing Fang,Chunsheng Lin,Deqing Guo,Ziyuan Qi,Ruikun Huo 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.4

In order to accurately measure the moving distance of the object and make the distance measurement more intelligent, a distance system is designed based on the Micro Electro-Mechanical System accelerometer. The modular design idea is used to design the three modules of the system, including acceleration measurement module, the acceleration storage module and the acceleration control module. The integrated packaging technology is used to realize the combination of the carrier and the distance system, so that the system can achieve acceleration real-time measurement, storage and other functions on the overload condition. The purpose of real-time calculation of the carrier’s moving distance is realized. And it can upload the stored data to the computer for further analysis and processing. The light gas gun test shows that the system has high anti-overload capability, and it can realize real-time measurement and calculation of motion acceleration. The precision of the distance measuring system can be up to 98.39%.

Sol–gel preparation, band structure, and photochemical activities of double perovskite <i>A</i> ₂NiWO₆ (<i>A</i> =Ca, Sr) nanorods

Xu, Lei,Qin, Chuanxiang,Wan, Yingpeng,Xie, Hongde,Huang, Yanlin,Qin, Lin,Seo, Hyo Jin Elsevier 2017 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.71 No.-

<P><B>Abstract</B></P> <P> <I>A</I> <SUB>2</SUB>NiWO<SUB>6</SUB> (<I>A</I> =Ca, Sr) double perovskite semiconductors were prepared via the sol–gel method. The crystal phases were confirmed via X-ray powder diffraction (XRD) measurements together with Rietveld refinements. The morphological and chemical properties of the samples were investigated by the scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and the specific surface area measurements. The optical absorptions and the band structures of the two double perovskites were discussed based on the on the experimental results and theoretical calculation. The d–d allowed transitions in Ni<SUP>2</SUP> <SUP>+</SUP>–O octahedra have great contributions to the narrow band-gap. The Ni<SUP>2+</SUP>-containing tungstate perovskites were potential photocatalysts, which are efficient for its photodegradation for methylene blue (MB) under the irradiation of visible light (λ<ce:italic/>> 420nm). The photocatalytic activities were attributed to the special structure properties and multivalent Ni and W ions in the perovskite lattices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>A</I> <SUB>2</SUB>NiWO<SUB>6</SUB> (<I>A</I> =Ca, Sr) nano-perovskite were prepared via the sol–gel method. </LI> <LI> The crystalline crystal structure was refined. </LI> <LI> The optical absorption and band structure were clarified. </LI> <LI> The photocatalysis activities were discussed on structural properties. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Homosexual film creation under the influence of queer theory

Xu Lei(쉬레이),Hyun-seok Lee(이현석) 한국정보통신학회 2021 한국정보통신학회 여성 ICT 학술대회 논문집 Vol.2021 No.8

퀴어 이론은 성적 권리의 관점에서 생물학적 젠더, 사회적 젠더 및 성적 지향 간의 관계를 해체하고 구성하는 혁명적인 이론이다. 게이 그룹은 퀴어 이론을 자신의 권리를 위해 싸울 이론적 무기로 사용한다. 현재 퀴어 이론에 기반한 많은 영화가 제작되고 있으며, 대부분은 동성 간의 관계를 다루고 있다. 이는, 영화의 전통적인 젠더 개념에 반하는 장르이다. 본 논문은 주로 현대 동성애 영화에 대한 퀴어 이론의 중요성을 논의하고 현재 영화 산업에서 게이 영화의 향방을 예측하고자 한다. Queer theory is a powerful and revolutionary theory, which deconstructs and constructs the relationship among biological gender, social gender and sexual orientation from the perspective of sexual rights. Gay groups take queer theory as a theoretical weapon to fight for their rights. At present, there are many movies based on queer theory, most of which are about the relationship between the same sex, and these movies are a challenge to the traditional gender concept. This paper mainly discusses the significance of queer theory to contemporary homosexual film and analyze the survival status of these excellent gay films in the current film industry.

Distinctions Between Clinicopathological Factors and Prognosis of Alpha-fetoprotein Negative and Positive Hepatocelluar Carcinoma Patients

Xu, Jia,Liu, Chang,Zhou, Lei,Tian, Feng,Tai, Ming-Hui,Wei, Ji-Chao,Qu, Kai,Meng, Fan-Di,Zhang, Ling-Qiang,Wang, Zhi-Xin,Zhang, Jing-Yao,Chang, Hu-Lin,Liu, Si-Nan,Xu, Xin-Shen,Song, Yan-Zhou,Liu, Jun,Z Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.2

Serum alpha-fetoprotein (AFP) is a significant marker for clinical diagnosis and prognosis evaluation in hepatocellular carcinoma (HCC) patients. However, some proportion of liver cancer patients are AFP-negative (AFP ${\leq}$20ng/ml). In order to study the differences between clinicopathological factors and prognosis of alpha-fetoprotein negative and positive patients, a total of 114 cases (41 AFP-negative and 73 AFP-positive) were selected for our research. By systematically statistical analysis, the results demonstrated that compared with AFP-negative patients, AFP-positive examples were more likely to feature cirrhosis nodules, non-complete neoplasm capsules, and a poor Edmondson-steiner grade. Furthermore, AFP-negative patients demonstrated a favorable long-term prognosis. By univariate analysis and multivariate analysis with Cox's proportional hazards model, multiple tumors were found to be independent risk factors for worse survival of AFP negative patients; however, less tumor-free margins, multiple tumors and Edmondson-steiner grades III/IV, proved to be independent risk factors leading to a poor prognosis of AFP positive cases. Finally, we can infer that high levels of AFP signify a highly malignant tumor and unfavorable prognosis.

Research on the Location Model Based on Clustering Local Search Algorithm under Electronic Commerce

Lei Xu,Jinshuan Peng 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.6

Internet is changing customers’ consumption patterns and the manufactures’ sale model. With the development of the computer network technology and the electronic commerce, more and more firms establish the electronic sale channel and get great profits. The huge supply chain network is established through the new idea and the technology. In this paper, we propose an improved local search algorithm- clustering local search algorithm (CLSA) to solve the hybrid location problem. We apply this method to distribution center location model and get the optimal solution. Result shows that this method can avoid the exponential explosion and get a good solution. In numerical analysis, we compare this method with simulated annealing method and ant searching algorithm. The numerical analysis demonstrates that this CLSA method not only classifies simply and flexibly, but also has the characteristic of fast search speed and small search space.