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Effect of Time Interval on Speed Estimation using Single Loop Detector Measurements
Jianhua Guo,Wei Huang,Yun Wei,Lin Zhang 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.5
Considering the importance of estimating speed from single loop detector measurements for many Intelligent Transportation System (ITS) related applications, a variety of algorithms have been developed in the literature for specific time intervals. However,the performance of these algorithms over a spectrum of time intervals has not yet received appropriate attention in the transportation research community. In this study, a Kalman filter based algorithm is selected as a typical representative and investigated over a spectrum of 30 time intervals starting from 1-minute to 30-minute with one minute increment. Empirical results using real world data show that the selected algorithm has workable performances for most of the time intervals under investigation. Specifically, the performances of the selected approach improve for intervals from 1-minute to 5-minute, stay stable for intervals between 5-minute and 15-minute, and decrease slightly for longer time intervals greater than 15-minute. The results demonstrate the ability of the selected algorithm to be readily implemented in a variety of transportation applications with specific time interval needs. Future work is recommended to develop a framework of coupling speed estimating algorithms and real world transportation applications through investigating other single loop speed estimation approaches and ITS application related time interval needs.
Weakly np-Injective Rings and Weakly C2 Rings
Wei, Junchao,Che, Jianhua Department of Mathematics 2011 Kyungpook mathematical journal Vol.51 No.1
A ring R is called left weakly np- injective if for each non-nilpotent element a of R, there exists a positive integer n such that any left R- homomorphism from $Ra^n$ to R is right multiplication by an element of R. In this paper various properties of these rings are first developed, many extending known results such as every left or right module over a left weakly np- injective ring is divisible; R is left seft-injective if and only if R is left weakly np-injective and $_RR$ is weakly injective; R is strongly regular if and only if R is abelian left pp and left weakly np- injective. We next introduce the concepts of left weakly pp rings and left weakly C2 rings. In terms of these rings, we give some characterizations of (von Neumann) regular rings such as R is regular if and only if R is n- regular, left weakly pp and left weakly C2. Finally, the relations among left C2 rings, left weakly C2 rings and left GC2 rings are given.
Effect of O2 Plasma Treatment on Density-of-States in a-IGZO Thin Film Transistors
Xing-Wei Ding,Fei Huang,Sheng Li,Jianhua Zhang,Xue-Yin Jiang,Zhi-Lin Zhang 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.1
This work reports an efficient route for enhancing the performanceof amorphous InGaZnO (a-IGZO) thin film transistors (TFT). Themobility was greatly improved by about 38% by means of O2plasma treatment. Temperature-stress was carried out to investigatethe stability and extract the parameters related to activation energy(Ea) and density-of-states (DOS). The DOS was calculated on thebasis of the experimentally obtained Ea, which can explain theexperimental observation. A lower activation energy (Ea, ~0.72 eV)and a smaller DOS were obtained in the O2 plasma treatment TFTbased on the temperature-dependent transfer curves. The resultsshowed that temperature stability and electrical propertiesenhancements in a-IGZO thin film transistors were attributed to thesmaller DOS.
Xing-Wei Ding,Jianhua Zhang,Weimin Shi,Hao Zhang,Chuanxin Huang,Jun Li,Xueyin Jiang,Zhilin Zhang 한국물리학회 2014 Current Applied Physics Vol.14 No.12
The instability of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) with different active layer thicknesses under temperature stress has been investigated through using the density-of-states (DOS). Interestingly, the a-IGZO TFT with 22 nm active layer thickness showed a better stability than the others, which was observed from the decrease of interfacial and semiconductor bulk trap densities. The DOS was calculated based on the experimentally-obtained activation energy (EA), which can explain the experimental observations. We developed the high-performance Al2O3 TFT with 22 nm IGZO channel layer (a high mobility of 7.4 cm2/V, a small threshold voltage of 2.8 V, a high Ion/Ioff 1.8 107, and a small SS of 0.16 V/dec), which can be used as driving devices in the next-generation flat panel displays.
A Clustering Approach to Online Freeway Traffic State Identification Using ITS Data
Jingxin Xia,Wei Huang,Jianhua Guo 대한토목학회 2012 KSCE JOURNAL OF CIVIL ENGINEERING Vol.16 No.3
Online traffic state identification plays an important role in achieving the potentials promised by Intelligent Transportation Systems (ITS) on various traffic applications, e.g., real time traffic monitoring systems. Traditional approaches have shown the limitations in either obtaining the necessary pre-determined information or having difficulties in their online implementation. This paper introduces an online agglomerative clustering procedure for freeway traffic state identification using ITS data, represented by three traffic condition variables of flow rate, speed, and occupancy. An optimal fit of the statistical characteristics is provided by maximizing the intra-cluster data point distances and minimizing inter-cluster data point distances through a joint utilization of the Bayesian Information Criterion and the ratio of change of the dispersion measurements. Test results show that the identified freeway traffic states through the proposed procedure are reasonable and consistent with the common understandings on freeway traffic operating conditions.
Path Optimization Algorithms Based on Graph Theory
Biyuan Yao,Jianhua Yin,Hui Zhou,Wei Wu 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.6
Transport with minimum time cost and distance remains to be an important research area in intelligent transport systems. Shortest path algorithms are primary methods to address simplified problems, which could not be well applied in high-dimensional real situations. We realized the minimum cost and maximum flow result via classical iterative algorithm based on graph theory, adjacency matrix is well applied to express the relationship between transport nodes, a topological sorting transport map is adopted to verify these approaches.
Predictions of Wake and Central Mixing Region of Double Horizontal Axis Tidal Turbine
Stephen Oppong,Wei-Haur Lam,Jianhua Guo,Leng Mui Tan,Zhi Chao Ong,Wah Yen Tey,Yun Fook Lee,Zaini Ujang,Ming Dai,Desmond Robinson,Gerard Hamill 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.7
Predicting the velocity distribution of double horizontal axis tidal turbines (DHATTs) is significant for the effective development of tidal streams. This current research gives an account on double turbine wake theory and flow structure of DHATT connected to single support by using the joint axial momentum theory and computational fluid dynamics (CFD) method. Characteristics of single turbine wake were previously studied with two theoretical equations predicting the initial upstream velocity closer to the turbine, and it’s lateral distributions along the downstream of the turbine. This current works agreed with the previous wake equations, which was used for predicting the velocity region along the downstream of the turbines. Flow field separating the two turbines is complicated in nature due to the indirect disturbance of turbines and no report was found on this central region. The Central region in the downstream flow is initially suppressed due to the blockage effects with a high velocity close to the free stream. Lateral expansion of two turbine wakes penetrated the central region with velocity reduction and followed by the flow recovery further downstream. This work provides more understandings of the wake and its central mixing region for double turbines with a proposed theoretical model.
A significant improvement of foam performance using Pluronic in molybdenum flotation
Zechao Huangfu,Wei Sun,Yue-hua Hu,Chen Chen,Sultan Ahmed Khoso,Qingpeng Zhang,Jiande Gao,Jianhua Kang 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.61 No.-
In present study, a significant improvement of molybdenum recovery was obtained through improving foam performance using Pluronics (L-61 and L-65), which were used as foam conditioner. The solution properties of L-61 and L-65, such as foamability, bulk rheology, and foam stabilities, on the flotation, were investigated through surface tension and rheological measurements. Results showed that the foam performance of fusel/L-65 composite system was better than those of fusel and fusel/L-61. Moreover, it was forever confirmed by bench-scale flotation that the recovery was increased by 5%, indicating that the foam performance could be improved with addition of L-65.