A Quality-Oriented Data Collection Scheme in Vehicular Sensor Networks

Nie, Wendi,Lee, Victor C. S.,Niyato, Dusit,Duan, Yaoxin,Liu, Kai,Nutanong, Sarana IEEE 2018 IEEE Transactions on Vehicular Technology VT Vol.67 No.7

<P>Considerable research attention has been dedicated to vehicular sensor networks (VSNs) because of its great potential in traffic monitoring. By taking advantage of sensors embedded in vehicles, a VSN harvests data while vehicles are traveling along the roads and then updates the collected data to the infrastructure to support the intelligent transportation system (ITS) applications. To meet the data collection requirements of different ITS applications, a huge number of update packets are generated, which may exhaust the available wireless communication bandwidth. To improve the efficiency of utilization of wireless bandwidth, in this study, we propose a <I> quality-oriented data collection</I> scheme, which aims to effectively support both the accuracy and real-time requirements stipulated by ITS applications while reducing communication overhead. We formulate a <I>minimized communication overhead (MCO)</I> problem and propose two algorithms, <I>mixed-integer linear programming (MILP)</I> and <I>deviation-detection (DD)</I>, to solve the MCO problem. MILP can obtain the optimal solution by having all the data collected by every vehicle, while DD could achieve an efficient solution without this impractical assumption. We conducted extensive experiments by using SUMO to simulate vehicle traces in freeway and downtown environments. The experimental results have demonstrated the effectiveness of the proposed solutions.</P>

Research on Hybrid Dynamic Capacitor-a novel approach to VAR compensation and resonance suppression

Zhang Kai,Lei Wanjun,Cheng Nie,Yue Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, a control method named hybrid dynamic capacitor is proposed to provide dynamic VAR compensation and suppress resonance between power capacitor and system inductance in power distribution network. This paper explains the theory of hybrid dynamic capacitor and this method benefits by reducing the initial cost, switching loss and less harmonic current. Finally, simulation and experiment results are given to verify the viability and effectiveness of the hybrid dynamic capacitor and its compensation characteristic.

Modeling and Analysis of Harmonic Resonance in Microgrid and Research of Active Harmonic Resistance Method

Cheng Nie,Wanjun Lei,Huajia Wang,Kai Zhang,Yue Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In the microgrid, the capacitive element such as compensation capacitor may resonance with the line inductance in harmonic frequency, furthermore serious harmonic resonance may endanger the system. In this paper, resonance mode analysis (RMA) method is used to analysis the harmonic resonance in the microgrid. To suppress the amplified of harmonic current near resonance frequency, an improved current control method for active harmonic resistance (AHR) is proposed. Simulation and experimental results reveal that the proposed method can suppress the resonance in the microgrid effectively.

Analysis of Harmonic Transfer Characteristics and RAPF Installation Strategy in Power Systems

Tian Li,Wanjun Lei,Nie Cheng,Xiaojie Zhang,Guoqing Gao,F. Kai Li 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Power quality has become a new threat because of the distributed nature of disturbances caused by nonlinear loads and DGs. When harmonics are transmitted in a distribution network, they’ll be magnified by resonance between line capacitance and inductance, then worsen the harmonic in power systems. In this paper, a mathematical model for harmonic transfer characteristics of power system feeders is firstly established. Meanwhile, analyze the harmonic voltage propagation caused respectively by the background harmonic voltage source and harmonic current source, which provides an important theoretical basis for the treatment of harmonic pollution. In addition, a strategy is proposed to guide the optimal installation position and setting of external resistance of RAPF to achieve the minimum total distortion rate in the entire distribution network system, which can damp the harmonic resonant effectively. Simulation and experiments have been performed to verify the theoretical analysis and demonstrate the effectiveness of the proposed strategy.

Two New Species in the Family Cunninghamellaceae from China

( Heng Zhao ),( Jing Zhu ),( Tong-kai Zong ),( Xiao-ling Liu ),( Li-ying Ren ),( Qing Lin ),( Min Qiao ),( Yong Nie ),( Zhi-dong Zhang ),( Xiao-yong Liu ) 한국균학회 2021 Mycobiology Vol.49 No.2

The species within the family Cunninghamellaceae are widely distributed and produce important metabolites. Morphological studies along with a molecular phylogeny based on the internal transcribed spacer (ITS) and large subunit (LSU) of ribosomal DNA revealed two new species in this family from soils in China, that is, Absidia ovalispora sp. nov. and Cunninghamella globospora sp. nov. The former is phylogenetically closely related to Absidia koreana, but morphologically differs in sporangiospores, sporangia, sporangiophores, columellae, collars, and rhizoids. The latter is phylogenetically closely related to Cunninghamella intermedia, but morphologically differs in sporangiola and colonies. They were described and illustrated.

EFFECT OF HEAVY-DUTY DIESEL ENGINE OPERATING PARAMETERS ON PARTICLE NUMBER AND SIZE DISTRIBUTION AT LOW SPEED CONDITION

Bin Yang Wu,Qiang Zhang,Shun Kai Zhang,Xiao Kun Nie,Yu Han Li,Wanhua Su 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.4

Experiments and simulations were used to investigate the effect of a range of engine operating parameters and fuel characteristics on the particle size and particle number (PN) concentration at low speed and idle speed condition. The occurrence, size, and concentration of particles were tested against a range of parameters including start of injection (SOI), common rail pressure, exhaust gas recirculation (EGR) ratio and load. The results showed that the homogeneity of the mixture had the greatest impact on particle size and number concentration. The performance of particle is different at different levels of load. The particle were of nucleation mode at idle condition, and the cold idle particles had a slightly larger diameter than those produced at hot idle. By using the diesel and under high load, at EGR ratios of less than 20 %, most particles were of nucleation mode. At EGR ratios exceeding 20 %, nucleation-mode particles were gradually replaced by accumulation-mode particles. At EGR ratios above 30 %, most particles were of the accumulation mode. Under the same load, gasoline compression ignition produced particles of smaller size and reduced particulate mass (PM). The use of gasoline extended ignition delay, as the high volatility and octane number of the fuel improved the homogeneity of the mixture. Finally, a linear relationship was found between PM and PN. The relative contribution of the different factors to the formation of nucleationor accumulation-mode particles was investigated.

Partial Discharge Detection Method Based on DD-DT CWT and Singular Value Decomposition

Wu Chao,Gao Yiran,Wang Ruoyan,Wang Kai,Liu Siyang,Nie Yongjie,Wang Ping 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4

Partial discharge (PD) detection is signifi cant for insulation condition evaluation of electrical equipment. However, it often happens that the PD signals are submerged by interferences, which will cause the inaccurate detection results. In this paper, we propose a PD detection method based on double-density dual-tree complex wavelet transform (DD-DT CWT) and singular value decomposition (SVD) to solve this problem. The denoising method based on DD-DT CWT has better performance in both removing interferences and retaining features of PD signals. The inner product of the singular value matrix obtained by applying SVD to denoised high-frequency wavelet coeffi cient matrix can concisely represent the complexity of the tested signal, which can be used as a basis to judge the existence of the PD signal. Besides, Otsu algorithm is introduced to calculate the threshold to locate the appearance time of the PD signal. Experimental results show that the proposed method can detect the PD signal with the accuracy rate of 77.8% when PD signals are submerged by noises, while the traditional method cannot detect the existence of the PD signal. In addition, only the method proposed in this paper can detect the appearance time of the PD signal with the accuracy rate of 97.2%.

Near-Infrared Laser Stimulation of the Auditory Nerve in Guinea Pigs

Tian Guan,Jian Wang,Muqun Yang,Kai Zhu,Yong Wang,Guohui Nie 한국광학회 2016 Current Optics and Photonics Vol.20 No.2

This study has investigated the feasibility of 980-nm low-energy pulsed near-infrared laser stimulationto evoke auditory responses, as well as the effects of radiant exposure and pulse duration on auditoryresponses. In the experiments, a hole was drilled in the basal turn of the cochlea in guinea pigs. An opticalfiber with a 980-nm pulsed infrared laser was inserted into the hole, orientating the spiral ganglion cellsin the cochlea. To model deafness, the tympanic membrane was mechanically damaged. Acousticallyevoked compound action potentials (ACAPs) were recorded before and after deafness, and optically evokedcompound action potentials (OCAPs) were recorded after deafness. Similar spatial selectivity between opticaland acoustical stimulation was found. In addition, OCAP amplitudes increased with radiant exposure,indicating a photothermal mechanism induced by optical stimulation. Furthermore, at a fixed radiantexposure, OCAP amplitudes decreased as pulse duration increased, suggesting that optical stimulation mightbe governed by the time duration over which the energy is delivered. Thus, the current experiments havedemonstrated that a 980-nm pulsed near-infrared laser with low energy can evoke auditory neural responsessimilar to those evoked by acoustical stimulation. This approach could be used to develop optical cochlearimplants.

Removal of the Glycosylation of Prion Protein Provokes Apoptosis in SF126

Chen, Lan,Yang, Yang,Han, Jun,Zhang, Bao-Yun,Zhao, Lin,Nie, Kai,Wang, Xiao-Fan,Li, Feng,Gao, Chen,Dong, Xiao-Ping,Xu, Cai-Min Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.5

Although the function of cellular prion protein (PrP$^C$) and the pathogenesis of prion diseases have been widely described, the mechanisms are not fully clarified. In this study, increases of the portion of non-glycosylated prion protein deposited in the hamster brains infected with scrapie strain 263K were described. To elucidate the pathological role of glycosylation profile of PrP, wild type human PrP (HuPrP) and two genetic engineering generated non-glycosylated PrP mutants (N181Q/N197Q and T183A/T199A) were transiently expressed in human astrocytoma cell line SF126. The results revealed that expressions of non-glycosylated PrP induced significantly more apoptosis cells than that of wild type PrP. It illustrated that Bcl-2 proteins might be involved in the apoptosis pathway of non-glycosylated PrPs. Our data highlights that removal of glycosylation of prion protein provokes cells apoptosis.

Synergistic Enhancement of the Strength-Ductility for Stir Casting SiCp/2024Al Composites by Two-Step Deformation

Fu‑xiang Cao,Kun‑kun Deng,Cui‑ju Wang,Kai‑bo Nie,Wei Liang,Jian‑feng Fan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

The 10 μm 10 vol% SiCp/2024Al composites sheet was successfully fabricated by semi-solid stir casting followed withtwo-step deformation (extrusion and rolling). The two-step thermal deformation solves the sheet rolling formability of theSiCp/2024Al composites produced by stir casting. Compared with the SiCp/2024Al composites prepared by traditional powdermetallurgy, this paper innovatively studied the synergistic enhancement between CuAl2phase and SiCpon the mechanicalproperties. The result shows that the two-step deformation can significantly improve the uniformity of the distribution of SiCpand CuAl2phases. At the same time, the average size of the SiCpand CuAl2phase decreases after the two-step deformation. During the hot extrusion, SiCphas an obvious hindrance to the refinement of the CuAl2phase. Moreover, the SiCp/2024Alcomposites sheet exhibits excellent yield strength (295 MPa), ultimate tensile strength (489 MPa), and elongation (10.42%). The performance improvement of SiCp/2024Al after two-step thermal deformation is mainly attributed to the improvedinterface bonding strength of SiCp-2024 Al matrix, the refined SiCpand the more uniform distribution of SiCp.