Simulation of travelling performance and experimental research on heavy double crawlers on a soft ground

Guanyu Zhang,Xinhui Liu,Shuai Wang,Guoqiang Wang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2

This study analyzes resistances to sinking, steering bulldozer, steering friction, running, climbing, inertia, and wind and considered the offsetting effects of instantaneous center of speed and center of mass based on the sinkage method proposed by Bekker. The purpose of the analysis is to show the calculation method for the driving power of crawlers under different working conditions. The influence of several performance factors were analyzed to calculate the steering performance of a dumping machine with heavy double crawler. The performance factors include steering radius, offset mass, width-to-length ratio, crawler width wider than the interior and lateral, caterpillar gauge in crawler drive, drive power, and steering torque friction. These factors are involved in driving wheels at a crawler speed of 3.33 RPM. The law of operation for heavy crawlers under different working conditions is obtained by performing a real vehicle test. The results of this test are compared with the theoretical calculations to verify correctness. Such a test provides important theoretical basis for theoretical modeling and for analyzing the performance of large crawlers running on soft ground.

회고와 창신: 홍콩 미술사 연구의 역사와 현황

왕관위 ( Wang Guanyu ) 덕성여자대학교 인문과학연구소 2021 인문과학연구 Vol.0 No.32

홍콩의 미술사의 흥기와 발전의 맥락은 그 특수한 시공간과 밀접하게 관련되어 있다. 공간적으로 중국 본토를 등에 대고 최상의 교통로인 주강(珠江) 하구가 밖으로는 남중국해에 인접하여 세계와 연결되어 우위를 점하고 있다. 역시 이 지리적인 이점으로 19세기 초에 영국이 홍콩섬을 점령한 뒤 100여 년 동안 영국의 해외영토로서 발전하여 1997년 홍콩이 중국으로 반환되어 특별 행정자치구로 된 것도 예사롭지 않은 역사이다. 중국과 영국 정부의 다른 통치 정책, 역사적으로 홍콩 문제에 대한 양국 간의 힘겨루기는 모두 홍콩 사회에 심대한 영향을 끼쳤다. 독특한 지리적 위치와 역사적 배경은 홍콩에서 미술사 연구가 중국 본토, 세계 지형과 깊고도 미묘하게 관련되도록 하였다. 홍콩에서 처음으로 미술사 연구를 제공한 학과가 홍콩중문대에 설립되었다. 중문대의 건립은 영국의 해외영토에서 단 한 곳의 고등학원만 허용하였던 철칙을 깨뜨렸고 영어 이외에 중국어로 수업을 하는 등 중국 전통문화를 확산시킨다는 취지로 중국 고대문화 미술을 중심으로 홍콩에서 미술사 연구를 시작하였다. 반세기에 가까이 발전을 거듭한 학과는 이제 본토에 기댄 채 세계를 향해 나아간다는 문화적 자세로 본토의 정체성과 문화적 정체성을 강조하며 새로운 탐구를 전개하고 있다. 이에 따라 홍콩중문대 미술학과와 홍콩중문대 미술관의 경우, 현지 대학 및 박물관 예술기관과 연계해 분석하고 홍콩에서 미술사 연구가 학문적 초창기에서 성숙기로 이어지는 주요 과정을 체계적으로 소개하여 홍콩 현지의 미술사 연구의 독특한 전통과 강점을 이해하고 이를 바탕으로 발전된 다원적 지향성과 풍부한 성과를 제시하였다. As for the context of the rise and development of the art history of Hong Kong, it is closely related to the specific space and time. Spatially, sitting back to Mainland China, its Pearl River estuary, the best transportation route is adjacent to the South China Sea to the outside, and it has an advantage, connected to the world. Also, thanks to this geographic advantage, it had been developed into one of the British territories overseas for about 100 years since the U.K. occupied Hong Kong Island in the early 19th century, was returned to China in 1997 and became a special administrative region. These are unusual histories, too. The different governing policies between the Chinese and British governments and a trial of strength between the two countries on the issue of Hong Kong historically had profound impacts on Hong Kong society. Hong Kong’s unique geographic location and historical background related studies of art history to mainland China and world topography deeply and subtly. The department that provided research on art history for the first time in Hong Kong was opened at the Chinese University of Hong Kong. The establishment of the Chinese University of Hong Kong broke the ironclad rule that had permitted only one higher education institute in British territories overseas and started research on art history in Hong Kong, centering around ancient Chinese culture and art intending to spread traditional Chinese culture, e.g. Giving classes in Chinese. The department that has been developed for nearly half a century now develops a new exploration, emphasizing the identity of the mainland and its cultural identity with a cultural attitude to go to the world, relying on the mainland. Thus, the Chinese University of Hong Kong Department of Fine Arts and the Chinese University of Hong Kong Art Museum understood the unique tradition and strong point of research on art history in Hong Kong and presented advanced pluralistic orientation and rich achievements based on that, conducting analysis in connection with local universities, museums, and art institutions and systematically introducing the main process in which research on art history in Hong Kong continued from early academic years to a mature stage.

Flexible cascaded multilevel inverter with multiple operation modes

Wang, Yaoqiang,Du, Guanyu,Liang, Jun,Qin, Ming The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.3

In this paper, a flexible cascaded multilevel inverter is proposed with a wide operational range. The inverter can change its topology structure to operate in three modes by a bidirectional switch unit. The nine-level or five-level mode of the inverter is adopted to optimize the output waveform when the input power is low. To decrease power losses, the three-level mode of the inverter is adopted to reduce the number of active switch devices when the input power is high. The topology and modulation strategy of the proposed inverter are presented and analyzed. The total losses and current THD of the inverter are calculated. In addition, simulations and experiments are conducted. The obtained simulation and experimental results indicate the correctness and feasibility of the proposed inverter and its modulation strategy.

Density-based Outlier Detection in Multi-dimensional Datasets

Xite Wang,Zhixin Cao,Rongjuan Zhan,Mei Bai,Qian Ma,Guanyu Li 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.12

Density-based outlier detection is one of the hot issues in data mining. A point is determined as outlier on basis of the density of points near them. The existing density-based detection algorithms have high time complexity, in order to reduce the time complexity, a new outlier detection algorithm DODMD (Density-based Outlier Detection in Multidimensional Datasets) is proposed. Firstly, on the basis of ZH-tree, the concept of micro-cluster is introduced. Each leaf node is regarded as a micro-cluster, and the micro-cluster is calculated to achieve the purpose of batch filtering. In order to obtain n sets of approximate outliers quickly, a greedy method is used to calculate the boundary of LOF and mark the minimum value as LOF i . Secondly, the outliers can filtered out by LOF i , the real outliers are calculated, and then the result set is updated to make the boundary closer. Finally, the accuracy and efficiency of DODMD algorithm are verified on real dataset and synthetic dataset respectively.

A comparison of Monte Carlo methods for computing marginal likelihoods of item response theory models

Yang Liu,Guanyu Hu,Lei Cao,Xiaojing Wang,Ming-Hui Chen 한국통계학회 2019 Journal of the Korean Statistical Society Vol.48 No.4

Nowadays, Bayesian methods are routinely used for estimating parameters of item response theory (IRT) models. However, the marginal likelihoods are still rarely used for comparing IRT models due to their complexity and a relatively high dimension of the model parameters. In this paper, we review Monte Carlo (MC) methods developed in the literature in recent years and provide a detailed development of how these methods are applied to the IRT models. In particular, we focus on the ‘‘best possible’’ implementation of these MC methods for the IRT models. These MC methods are used to compute the marginal likelihoods under the one-parameter IRT model with the logistic link (1PL model) and the two-parameter logistic IRT model (2PL model) for a real English Examination dataset. We further use the widely applicable information criterion (WAIC) and deviance information criterion (DIC) to compare the 1PL model and the 2PL model. The 2PL model is favored by all of these three Bayesian model comparison criteria for the English Examination data.

Rejoinder: A comparison of Monte Carlo methods for computing marginal likelihoods of item response theory models

Yang Liu,Guanyu Hu,Lei Cao,Xiaojing Wang,Ming-Hui Chen 한국통계학회 2019 Journal of the Korean Statistical Society Vol.48 No.4

Heat dissipation in high-power semiconductor lasers with heat pipe cooling system

Shili Shu,Guanyu Hou,Lijie Wang,Sicong Tian,Leonid L. Vassiliev,Cunzhu Tong 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6

This study focuses on the application of heat pipes in thermal management for high-power semiconductor lasers. The heat pipe cooling systems are used for heat dissipation in high-power semiconductor lasers. These systems are used instead of water cooling machines to realize a compact and lightweight laser module. The n-shaped heat pipe cooling system, which consists of eight 6 mm copper heat pipes with sintered powder wicks, can easily handle a heat load of up to 73 W from a single-laser unit. The fabricated U-shaped heat pipe cooling system, which consists of ten 12 mm copper heat pipes with sintered powder wicks, can easily handle a heat load of up to 300 W from five laser units. The optical power of the multi-laser module cooled by the U-shaped heat pipe cooling system reaches 210 W. These results indicate that high-power semiconductor lasers can be cooled using heat pipe cooling systems instead of water cooling machines.

RESEARCH ON MILLIMETER WAVE RADAR SIMULATION MODEL FOR INTELLIGENT VEHICLE

Xin Li,Weiwen Deng,Sumin Zhang,Yaxin Li,Shiping Song,Shanshan Wang,Guanyu Wang 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.2

Radar simulation models can effectively overcome the drawbacks of real vehicle experiment and speed up the development process of intelligent vehicle technologies based on millimeter wave radar via virtual testing. However, there are still many gaps between the radar model using in the virtual driving environment and the real radar. In this paper, a novel simulation model of intelligent vehicle millimeter wave radar is proposed. Based on the analysis of the real radar performance in typical application scenes, the radar model considers the mechanism and characteristics of the vehicle radar synthetically and a systematic radar modeling architecture with innovation is introduced. The highlights of this radar model include the design of the RCS simulation model for radar targets with both high accuracy and real-time performance, the establishment of the quantitative false alarm model, missed detection model and measurement error simulation model. Vast amounts of data collected by real vehicle radar are applied to fetch model parameters and verify the accuracy of the radar model. Simulation results show that the proposed model can reach both high reliability and computational efficiency.