New methodologies for predicting corridor travel time mean and reliability

Zifeng Wu,Laurence R. Rilett,Weijun Ren 서울시립대학교 도시과학연구원 2022 도시과학국제저널 Vol.26 No.3

Accurate travel time prediction is very important for real-time traveller information systems. Many existing traveller information systems provide point estimates of forecast travel times. Often the forecast corridor travel time is estimated as a direct summation of the forecast link travel times on the route. This approach neglects the correlation between link travel times and may lead to inaccurate route travel time forecasts. This paper improves upon the simple addition method by accounting for the dependency of link travel times on the arrival time at that specific link which further correlates to its preceding links. In addition, this paper also explores the potential of using the nonlinear autoregressive with exogenous inputs (NARX) model and feedforward neural network model to forecast the corridor travel time mean and reliability metrics. To the authors knowledge this is the first time, short-term travel time reliability is measured by a reliability interval which is based on the forecasts of corridor travel time mean and standard deviation. The prediction methodologies developed in this paper are tested on an urban arterial that has been instrumented with Bluetooth readers so empirical travel times are available. It was found that the proposed NARX model outperforms the other models that were studied with respect to mean corridor travel time prediction. In terms of the reliability interval prediction, the performance of various models is presented as a Pareto Optimal Frontier trading off accuracy and usability. The proposed NARX model and three other tested models are all on the Pareto Optimal Frontier.

Effect of Different Reinforced Load Transfer Platforms on Geosynthetic-Reinforced Pile-Supported Embankment: Centrifuge Model Test

Di Wu,Chen Luo,Zifeng Gao,Dan Li,Chao Xu 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.2

Geosynthetic-reinforced pile-supported (GRPS) embankment has been widely utilized in the railways and highways subgrade of soft clay area. The load transfer platform (LTP), consisting of sand layers and one or more layers of geosynthetic, is constantly used at the base of embankment to increase the load transfer to piles and reduce the differential settlement of embankment surface. However, the effect of different reinforced LTPs on the performances of GRPS embankment has not been fully understood. Eight centrifuge model tests were conducted to investigate the effect of five influence factors on deformation and load transfer of embankment, and tensile force of geogrid: placing geogrid or not, the number of geogrid layers, geogrid reinforced position, geogrid stiffness, wrapped-back geogrid setting in LTP. The results showed that the wrapped-back geogrid setting in the LTP was equivalent to anchoring the geogrid at the slope toe of embankment, which strengthened the reinforcement-soil interaction and restricted the pull-out displacement of geogrid to enhance the stiffness for LTP. The LTP reinforced with stiffer geogrid or multi-layer geogrid contributed to increase the stability and load transfer of embankment due to the increase of the integrity stiffness for LTP. When the geogrid was set at the middle of LTP, the performances of the GRPS embankment was enhanced due to the more interfaces between the geogrid and soil to improve the integrity stiffness of the LTP. The two-layer geogrid reinforced in the LTP could be the best choice to enhance the performance of the GRPS embankment under the comprehensive consideration of the performance and economy. The five setting ways of the reinforcement in LTP increased the integrity stiffness of LTP, which provided more methods to enhance the performances of the GRPS embankment.

명말청초 중국 소설에 드러난 경계적 공간으로서 조선의 형상화

권대광(Kwon DaeKwang),오자봉(Wu Zifeng) 국어문학회 2022 국어문학 Vol.81 No.-

이 글에서는 명말 청초 중국 소설에서 보이는 조선에 관한 관심을 탐구하였다. 당시 중국과 조선은 문인들의 교류가 지속적으로 이루어졌음에도 불구하고 조선에 대한 실체적 인식을 서사에 담아내지 못했다. 또, 문화교류가 지배계급을 중심으로 이루어진 탓에 중국 소설의 주요 창작 계층은 조선에 대한 정확한 인식을 갖고 있지 못했다. 이 때문에 조선에 대해 제한적으로 알려진 피상적인 정보를 활용해 조선에 대한 이미지를 구축할 수밖에 없었다. 중국 소설 속 조선은 배타적 화이론의 관념적 틀 안에서 그려지며, 중화의 주변국이자 문명 개화의 가능성을 지닌 것으로 나타나지만, 여전한 야만성을 지니고 있는 공간으로 그려짐으로써 소설 속에서 경계적 공간으로 나타나고 있다. 이 글에서 조망했던 네 작품 중 〈無聲戱〉, 〈女仙外史〉, 〈閱微草堂筆記〉에는 조선이 등장한다. 의식적인 측면에서 이 작품들은 조선에 대한 중국의 우월의식을 보여주고 있으며, 〈李谪仙醉草嚇蠻書〉에서 등장한 발해와 마찬가지로 이적의 무리 속에 조선을 위치시키고 있다. 조공 국가로서 조선의 실체를 국한하고, 조선인에 대한 배타적 시각을 소설 서사에서 제시함으로써 문화적 이질성을 거부했던 당대 소설 문화적 토양의 한계를 알 수 있다. 이러한 소설적 경향은 명말 청초 시기 소설작품들은 당대 청나라와 조선의 교류 관계와는 별개로 조선을 화이론적 세계관 속에 위치시키고, 환상적 공간으로 조선을 만들어 냈다. 당대 조선과 청나라 사대부들의 문화적 교류에도 불구하고, 이러한 교류는 동아시아의 연대를 이끌어 내는 사회적 담론으로 성장하지 못했던 것으로 보인다. This article explores the perception of Joseon in Chinese novels in the 17th and 18th centuries. At that time, China and Joseon could not escape from the exchange centered on poetry and literature despite the continuous exchange of literary figures. Also, because cultural exchanges were centered on the ruling class, the creative classes of Chinese novels did not have an accurate understanding of Joseon. For this reason, they had no choice but to build an image of Joseon by using the limited known superficial information about Joseon. On the other hand, the Hwa-I theoretic worldview, which can be said to be the frame of Chinas traditional external perception, has been positioned as a primary tool for depicting the image of Joseon in the novel. Among the four works reviewed in this article, the Joseon Dynasty appears in 〈Museong-hi〉〈Yeolmichodangpilgi〉. From a ceremonial point of view, these works show Chinas sense of superiority over Joseon, and, like Balhae, which appeared in 〈I-jeokseon chuicho hyukmanseo〉, places Joseon amid a gang of I, the outlanders. By limiting the reality of Joseon as a tribute state and presenting an exclusive perspective on Koreans in the narrative, we can see the limits of the cultural circumstance of the 17∼18c Chinese novel, which rejected cultural heterogeneity. This novel tendency in 17∼18c placed Joseon in the worldview of Hwa-I theory, independent of the exchange relationship between the Qing Dynasty and Joseon of the time, and created Joseon as a fantastic space. Despite the cultural exchanges between the Joseon and Qing dynasties, it seems that these exchanges did not develop into a social discourse that led to solidarity in East Asia.

Model predictive control of nine-switch converter with output filter for independent control of two loads

Pang, Yi,Zhang, Jingmei,Xu, Dongxing,Yin, Chang,Wu, Zifeng,Sun, Hexu,Pan, Lei The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

This paper proposes a model predictive control (MPC) algorithm designed for nine-switch converter with output filter (NSCOF) to control two three-phase AC loads independently. A state function of each leg of nine-switch converter (NSC) is established to characterize the internal conditions of the NSC because the traditional model of the NSCOF does not involve the interior model of the NSC. Based on the NSCOF model with the state function of each leg, a prediction model of NSCOF is constructed. The two AC terminals of NSCOF are treated as one module when the MPC is designed. The proposed MPC achieves controlling two three-phase AC loads working under different frequency modes. Furthermore, this algorithm is independent of the modulation method for reducing the difficulty of the controller design and its limits. The simulation and experimental results reveal that the steady-state and dynamic response performance of NSCOF are substantially improved using MPC.

Active noise cancellation frequency‑locked loop with a notch filter

Lei Pan,Dongxing Xu,Jingmei Zhang,Chang Yin,Zifeng Wu,Yingjun Guo 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.12

To improve the performance of frequency-locked loops (FLLs) under distorted grid conditions, a series of pre-filtering techniques have been added to remove harmonics. One of them is the FLL-based comb filter (COMB-FLL), which offers a high disturbance rejection capability. However, it has some disadvantages, such as approximating a fractional delay and compensating an accumulated round-off error in the digital implementation of COMB-FLL. To alleviate these problems, this study proposes an active noise cancellation (ANC) FLL with a notch filter (NF), which incorporates an NF and an ANC to improve the frequency-locking ability. In this research, the structure of a comb filter is simplified into an NF, and an ANC is creatively introduced to eliminate harmonics from the frequency signal obtained by FLL. Furthermore, ANC has been improved to make it suitable for electricity-related applications. The proposed FLL features a unique cascade structure, which has excellent frequency-locking ability and dynamic characteristics under normal, abnormal, and harmonically distorted grid conditions. The simulations and experimental results verify the validity and reliability of the proposed FLL.

Structures, biomimetic synthesis, and anti-SARS-CoV-2 activity of two pairs of enantiomeric phenylpropanoid-conjugated protoberberine alkaloids from the rhizomes of Corydalis decumbens

Jing-Guang Lu,Yingwei Wang,Ming-Rong Yang,Cai-Yun Wang,Jieru Meng,Jiazheng Liu,Zifeng Yang,Kongsong Wu,Li-Ping Bai,Guo-Yuan Zhu,Zhi-Hong Jiang 대한약학회 2022 Archives of Pharmacal Research Vol.45 No.9

(±)-Decumicorine A ( 1 ) and (±)- epi -decumicorine A ( 2 ), two pairs of enantiomeric isoquinoline alkaloids featuring a novel phenylpropanoid-conjugated protoberberine skeleton, were isolated and purifi ed from the rhizomes of Corydalis decumbens . The separation of (±)- 1 and (±)- 2 was achieved by chiral HPLC to produce four optically pure enantiomers. The structures and absolute confi gurations of compounds (−)- 1 , (+)- 1 , (−)- 2 , and (+)- 2 were elucidated by spectroscopic analysis, ECD calculations, and X-ray crystallographic analyses. The two racemates were generated from a Diels-Alder [4 + 2] cycloaddition between jatrorrhizine and ferulic acid in the proposed biosynthetic pathways, which were fully verifi ed by a biomimetic synthesis. Moreover, compound (+)- 1 exhibited an antiviral entry eff ect on SARS-CoV-2 pseudovirus by blocking spike binding to the ACE2 receptor on HEK-293T-ACE2 h host cells.