An Application of Fiber-Connected Distributed Antennas to Heterogeneous Networks : Energy Efficiency Perspective

Ying Sun,Yuxian Huang,Liming Chen 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.1

Fiber-connected distributed antenna systems (DAS) have been recognized as an effective means to accommodate the coverage and capacity demands of future heterogeneous networks (HetNet). Among various opportunities realized by the architecture, our focus in this paper is on the spectral efficiency (SE) advantages achieved by cooperative transmission and the associated power consumption that may affect the energy efficiency (EE) of the system. A detailed power model is developed to benchmark the various sources of energy consumption in fiber-connected DAS. Then a simple but efficient pre-coding scheme is proposed to reduce the computation complexity associated with cooperative transmission, thus lowering the power consumed by baseband processing while at the same time maintaining a high throughput performance. Through detailed and extensive simulations, this paper demonstrates the SE and EE advantages of the application of fiber-connected DAS in HetNet.

What Affect Lower Grade Learner’s Perceived Usefulness and Perceived Ease of Use of Mobile Digital Textbook Learning System? An Empirical Factor Analyses Investigation in China

Haijiao Shen,Liming Luo,Zhong Sun 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.1

Although perceived usefulness and perceived ease of use are two important factors which could directly influence the acceptance of technology and actual usage for digital textbook, less attention has been paid to children’s mobile digital textbook usage. Therefore, the purpose of this study is to investigate and empirically validate the perceived usefulness and the perceived ease of use by elementary school students during their usage of digital textbook. For data analyses, two questionnaires were developed using existing scales from prior TAM instruments. The sample of this study included 5,245 elementary school students in China who have experience of using digital textbook. The results indicate that students believe that using mobile digital textbook enhance their study performance, but they believe it is not very easy to use. Besides, gender, grade and parents’ attitudes towards mobile digital textbook affect the usage. Gender differences exist only in the perceived ease of use. Male students make less effort in using mobile digital textbook than female students. In addition, the students in lower grades tend to have more positive perspectives on mobile digital textbook than the students in higher grades. Furthermore, mobile digital textbook usage experience (time & frequency) has a significant effect on the students’ perceived usefulness. Finally, parents’ attitudes towards mobile digital textbook influence their children’s perceived usefulness.

The Analysis on the Formation of Porosity During Pulsed Laser–Induced TIG Hybrid Welding of 6061 Aluminium Alloy at High Welding Speed

Jia Sun,Hongyang Wang,Liming Liu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.8

Reducing welding defects and improving welding manufacturing speed are important for the development of automated welding technology. Low-power pulsed laser–induced TIG hybrid welding method was used to join 6061-T6 aluminium alloy. The formation mechanism of porosity during the high speed welding process was investigated in different parameters, such as pulse frequency, pulse duration, pulse energy and arc current. The results showed that the pulse duration made influence on the energy fluctuations in the welding process, and there was an interaction between laser frequency and welding speed. The energy state of the pulsed laser became a key factor affecting the welding defect and appropriate arc current can effectively decrease the porosity generation.

A Robust Video Fingerprinting Algorithm Based on Centroid of Spatio-temporal Gradient Orientations

( Ziqiang Sun ),( Yuesheng Zhu ),( Xiyao Liu ),( Liming Zhang ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.11

Video fingerprints generated from global features are usually vulnerable against general geometric transformations. In this paper, a novel video fingerprinting algorithm is proposed, in which a new spatio-temporal gradient is designed to represent the spatial and temporal information for each frame, and a new partition scheme, based on concentric circle and rings, is developed to resist the attacks efficiently. The centroids of spatio-temporal gradient orientations (CSTGO) within the circle and rings are then calculated to generate a robust fingerprint. Our experiments with different attacks have demonstrated that the proposed approach outperforms the state-of-the-art methods in terms of robustness and discrimination.

99mTc-3PRGD2 SPECT/CT Imaging for Diagnosing Lymph Node Metastasis of Primary Malignant Lung Tumors

Xiao Liming,Yu Shupeng,Xu Weina,Sun Yishan,Xin Jun 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.11

Objective: To evaluate 99mtechnetium-three polyethylene glycol spacers-arginine-glycine-aspartic acid (99mTc-3PRGD2) singlephoton emission computed tomography (SPECT)/computed tomography (CT) imaging for diagnosing lymph node metastasis of primary malignant lung neoplasms. Materials and Methods: We prospectively enrolled 26 patients with primary malignant lung tumors who underwent 99mTc- 3PRGD2 SPECT/CT and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT imaging. Both imaging methods were analyzed in qualitative (visual dichotomous and 5-point grades for lymph nodes and lung tumors, respectively) and semiquantitative (maximum tissue-to-background radioactive count) manners for the lymph nodes and lung tumors. The performance of the differentiation of lymph nodes with and without metastasis was determined at the per-lymph node station and perpatient levels using histopathological results as the reference standard. Results: Total 42 stations had metastatic lymph nodes and 136 stations had benign lymph nodes. The differences between metastatic and benign lymph nodes in the visual qualitative and semiquantitative analyses of 99mTc-3PRGD2 SPECT/CT and 18F-FDG PET/CT were statistically significant (all P < 0.001). The area under the receiver operating characteristic curve (AUC) in the semi-quantitative analysis of 99mTc-3PRGD2 SPECT/CT was 0.908 (95% confidence interval [CI], 0.851–0.966), and the sensitivity, specificity, positive predictive value, and negative predictive value were 0.86 (36/42), 0.88 (120/136), 0.69 (36/52), and 0.95 (120/126), respectively. Among the 26 patients (including two patients each with two lung tumors), 15 had pathologically confirmed lymph node metastasis. The difference between primary lung lesions in patients with and without lymph node metastasis was statistically significant only in the semi-quantitative analysis of 99mTc-3PRGD2 SPECT/CT (P = 0.007), with an AUC of 0.807 (95% CI, 0.641–0.974). Conclusion: 99mTc-3PRGD2 SPECT/CT imaging may notably perform in the direct diagnosis of lymph node metastasis of primary malignant lung tumors and indirectly predict the presence of lymph node metastasis through uptake in the primary lesions.

Numerical study of wind profiles over simplified water waves

Shuyang Cao,Enzhen Zhang,Liming Sun,Jinxin Cao 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.21 No.3

Vertical profiles of mean and fluctuating wind velocities over water waves were studied, by performing Large-Eddy Simulations (LES) on a fully developed turbulent boundary layer over simplified water waves. The water waves were simplified to two-dimensional, periodic and non-evolving. Different wave steepness defined by a /λ ( a : wave amplitude; λ : wavelength) and wave age defined by c/Ub (c: phase velocity of the wave; Ub : bulk velocity of the air) were considered, in order to elaborate the characteristics of mean and fluctuating wind profiles. Results shows that, compared to a static wave, a moving wave plays a lesser aerodynamic role as roughness as it moves downstream slower or a little faster than air, and plays more aerodynamic roles when it moves downstream much faster than air or moves in the opposite direction to air. The changes of gradient height, power law index, roughness length and friction velocity with wave age and wave amplitude are presented, which shed light on the wind characteristics over real sea surfaces for wind engineering applications.

A Novel Vibration Model for Explanation of the Frequency Features in Multistage Wind Turbine Gearboxes Considering the Effects of Inter-stage Meshing Frequency Modulation

Yanyan Nie,Fangyi Li,Liming Wang,Jianfeng Li,Yanle Li,Mingshuai Sun,Mengyao Wang,Guoyan Li 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.1

As a kind of green energy, wind energy has become cost-competitive mainstream energy in the world. The gearbox is one of the most important and vulnerable components in the wind turbine (WT), which suffers a high failure rate and downtime. It is of great significance to the condition monitoring and fault diagnosis of the WT gearbox. However, in the multistage WT gearbox, the vibrations generated from different stages are coupled, which leads to a complex vibration spectral structure and brings difficulties in condition monitoring and fault diagnosis. Aiming to understand the vibration frequency features of multistage WT gearboxes, a novel phenomenological vibration model is established and the spectral structure is deduced by using the Fourier series analysis. In the vibration model, the phenomenon of inter-stage meshing frequency modulation (ISMFM) is considered, which is clearly proposed for the first time. The theoretical derivations are validated by both simulation and engineering tests using a 2.0 MW industrial WT gearbox. The results show that under healthy conditions, in addition to the meshing frequencies and their harmonics of each stage, there are also ISMFM sidebands in the vibration spectrum of the multistage WT gearbox, and the amplitude of the sidebands will change with the health status of the gearbox. The findings are not only applicable to the WT gearbox studied in this paper, but also to other similar multistage gearbox systems, which can provide a priori spectral structure for a multistage gear transmission system to assist its condition monitoring and fault diagnosis.

Molecular Epidemiology and Prevalence of Echovirus 30 in Zhejiang Province, China, from 2002 to 2015

( Yin Chen ),( Yi Sun ),( Juying Yan ),( Ziping Miao ),( Changping Xu ),( Yanjun Zhang ),( Haiyan Mao ),( Liming Gong ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.12

Echovirus serotype 30 (ECHO30) has been responsible for several recent worldwide outbreaks of viral meningitis. In Zhejiang Province, China, ECHO30 has been one of the main causes of viral meningitis for years. This study, using phylogenetic analysis of the VP1 gene, was performed to investigate the general molecular epidemiology and genetic patterns of ECHO30 circulating in Zhejiang Province between the years 2002 and 2015. The nucleotide sequences of ECHO30 VP1 showed that they were 64.8% identical with the prototype strain, Bastianni, while the amino acids were 84.9% identical. Phylogenetic analyses showed that ECHO30 in the Zhejiang area has diverged into two genotypes. Genotype I consists of strains isolated since 2002, whereas genotype II includes strains that were mainly isolated during the 2002 to 2004 outbreak. ECHO30 has been endemically circulating in both humans and the environment for a long period of time. Additionally, we evaluated the significance of recombination presented during the years 2005 to 2007 to demonstrate that recombination plays an important role in the prevalence of ECHO30 in the Zhejiang area.

Effect of Thermal Treatment on the Texture and Microstructure of Abalone Muscle (Haliotis discus)

Beiwei Zhu,Xiuping Dong,Liming Sun,Guihua Xiao,Xuejiao Chen,Yoshiyuki Murata,Chenxu Yu 한국식품과학회 2011 Food Science and Biotechnology Vol.20 No.6

The texture and microstructure of edible abalone meats were studied during heat treatments from 50to 100^oC for 60 min. No increase in extractable soluble collagen content was observed below 80^oC, but a 9-fold increase was observed at 100^oC. SDS-PAGE showed that extractable myosin heavy chains and paramyosin contents reduced significantly at 80^oC, and disappeared completely at 100^oC. The shear force increased slowly from 50 to 70^oC, but relaxed back to the initial level at 100^oC. Rapid reduction of hardness was observed at 50^oC, minimum hardness was obtained at 100^oC. Springness, cohesiveness,chewiness, and resilience were enhanced to maximum levels at 70, 90, 70, and 90^oC, respectively. Optical micrographs and transmission electron microscope showed a significant increase of intermyofibrillar gaps at 90^oC and broken fibers at 100^oC. Results suggested that 80^oC might be a suitable temperature to produce ready-to-eat abalone products.

Electrospun Porcine Acellular Dermal Matrix and Polycaprolactone Composite Nanofibrous Scaffolds for Accelerating Wound Healing

Xiaofei Gao,Guohua Jiang,Liming Ruan,Yanfang Sun,Khaydar E. Yunusov,Yanting Jing,Uladzislau E. Aharodnikau,Sergey O. Solomevich 한국섬유공학회 2023 Fibers and polymers Vol.24 No.2

Electrospun nanofibers represent a novel class of scaffold materials that show great potential in wound healing owing torelatively large surface area, better mimicry of native extracellular matrix, adjustable waterproofness and breathability, andprogrammable drug delivery process. In this work, electrospun polycaprolactone (PCL) and porcine acellular dermal matrix(PADM) composite nanofibrous membranes have been developed by electrospinning technology and inflated into threedimensional(3D) structural scaffold (PCL-PADM) by gas foaming method. The obtained PCL-PADM has higher thermalstability, hydrophilicity and better cell adhesion compared with PCL. In addition, ε-polylysine (ε-PL) is further attachedonto the surface of PADM/PCL to offer its good antibacterial properties. Moreover, the PADM/PCL fibrous scaffolds showexcellent cytocompatibility for promoting cell proliferation. In vivo models showed that the resultant PADM/PCL fibrousscaffolds exhibit an accelerating wound healing effect through promoting expression of vascular factor (CD31) and decreasingthe expression of tumor necrosis factor-α (TNF-α). These results indicate that the 3D fibrous scaffolds may be a potentialwound dressing for wound closure.