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Observing the Characteristics of Multi-Activity Trip Chain and Its Influencing Mechanism
Linbo Li,Mengfei Cao,Jiajun Yin,Yanli Wang,Sabyasachee Mishra 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.11
Understanding mechanism of daily activity trip chain especially multi-activity trip chain is significant for travel demand management and urban redevelopment. This paper explores the multi-activity trip chain behavior from both individual attributes and spatial attributes. Multi- activity trip chain is identified from people’s full-day travel diaries, then categorized into multi-activity intermittent trip chain and continuous trip chain to distinguish the characteristics and influencing factors of different chains. Using resident travel survey data of Xiaoshan District of Hangzhou, China, multinomial logistic regression model, transition probability matrix and activity analysis methods are employed to make analyses. Findings include: 1) making multi-activity trip chain can achieve multiple purposes with less average travel time for each purpose, but public transit is less used. 2) The choices of single or multi-activity trip chain and multi-activity intermittent or continuous trip chain are mainly affected by different individual attributes such as occupation, education, household income, etc. Moreover, household registration, driver’s license, gender, and household car ownership are related to the choice of activity sequence. 3) For typical trip chain with purposes of work, shopping/dining, and home, activity sequence is also obviously influenced by spatial distance between origin and destination, especially for the chain of work-shopping/dining-home.
Adaptive Virtual Impedance of Grid-Tied Inverters to Enhance the Stability in a Weak Grid
Yan Du,Qingqing Sun,Xiangzhen Yang,Linbo Cui,Jian Zhang,Fei Wang 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.3
In a weak grid, especially with a grid-voltage proportional feedforward controller, the grid-tied inverter tends to interact with the grid impedance and thus suff ers from poor power quality and even instability. In order to improve the stability, serial-parallel virtual impedance based on the derivative controllers of grid current and voltage is proposed in this paper. With the aim of optimizing the performance of the inverter for a variety of grid impedance, these derivative coeffi cients are adaptively tuned by the constraint of a minimum leading phase which is determined by the phase margin and the current tracking response. With this proposed adaptive virtual impedance, the grid-tied inverter can operate stably under a wide variety of grid impedance and voltage harmonic rejection performance is also improved. Simulation and experimental results validate the eff ectiveness of the proposed method and design methodology.
Post-quantum identity-based authenticated multiple key agreement protocol
Yang Yang,Hongji Yuan,Linbo Yan,Yinglan Ruan 한국전자통신연구원 2023 ETRI Journal Vol.45 No.6
Authenticated multiple key agreement (AMKA) protocols provide participants with multiple session keys after one round of authentication. Many schemes use Diffie-Hellman or authenticated key agreement schemes that rely on hard integer factorizations that are vulnerable to quantum algorithms. Lattice cryptography provides quantum resistance to authenticated key agreement protocols, but the certificate always incurs excessive public key infrastructure management overhead. Thus, a lightweight lattice-based secure system is needed that removes this overhead. To answer this need, we provide a two-party lattice- and identity-based AMKA scheme based on bilateral short integer or computational bilateral inhomogeneous small integer solutions, and we provide a security proof based on the random oracle model. Compared with existing AMKA protocols, our new protocol has higher efficiency and stronger security.