Dynamics modeling and modal experimental study of high speed motorized spindle

Yunsong Li,Xiaoan Chen,Peng Zhang,Jinming Zhou 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.3

This paper presents a dynamical model of high speed motorized spindles in free state and work state. In the free state, the housing is modeled as a rotor with equivalent masses including bearing pedestals, motor stator and rear end cover. As a consequence, a double rotor dynamics can be modeled for high speed motorized spindles by a bearing element which connects the housing and bearing pedestals. In the work state, the housing is fixed and the system becomes a bearing-rotor dynamical model. An excitation-measurement test in the free state is designed to analyze the cross spectral density and auto spectral density of input and output signals. Then the frequency response function of system and coherence function of input and output signals which are used to analyze the inherent characteristics of the double-rotor model can be obtained. The other vibration test in the work state is designed to research the dynamical supporting characteristics of bearings and the effects from bearings on the inherent characteristics of the system. The good agreement between the experimental data and theoretical results indicates that the dynamical model in two states is capable of accurately predicting the dynamic behavior of high speed motorized spindles.

Populist Terrorist Activities and their Impact in Pakistan

Bo Tu,Bingfeng Fu,Yunsong Zhou,Daitong Liang 한국정치사회연구소 2020 한국과 국제사회 Vol.4 No.1

In Pakistan, there are various types of populist organizations, among which some extreme populist organizations such as those in Baluchistan, Sindh, Gilgit and other regions have become extreme and taken on a certain terrorist nature because of Pakistan s history and politics as well as the long tradition of Pakistan s domestic terrorism. These extremist populist organizations have not only posed a threat to Pakistan s national security and development, but also hindered the strengthening of both China-Pakistan bilateral relations and the cooperation around the Belt and Road Initiative. The specific organizational structure of these extreme populist groups and the impact of their terrorist activities on both Pakistan and the rest of the world deserve attention in the academic community. By adopting a literature review approach, in this paper, Pakistan’s domestic populist organizations are sorted reasonably, the structure of extreme populist organizations is clarified accordingly, and the influence of their terrorist activities is noted emphatically. The conclusion drawn is that Pakistan’s domestic extreme populist groups have not only severely constrained Pakistan’s economic development and lowered the people’s living standards, but also hindered the strengthening of Pakistan’s diplomatic relations with neighboring countries, thus worsening Pakistan’s domestic political environment and impeding its integration into the trend of globalization. 파키스탄의 포퓰리즘 조직은 몇 가지 유형으로 나눌 수 있다, 그 중에 극단적 포퓰리즘 조직의 예를 들면 발루치스탄(Baluchistan), 신드(Sindh), 길기트(Gilgit) 등 지역의 포퓰리즘조직은 역사적, 정치적 원인으로 테러리즘 성질을 가지고 있다. 이러한 극단적 포퓰리즘 조직들은 파키스탄의 국가 안보 및 발전에 영향을 줄 뿐만 아니라 중-파 양국관계 및 “일대일로”를 중심으로 한 협력에도 영향을 준다. 이 조직들이 어떻게 형성되었는지, 어떤 특징을 갖고 있는지를 연구하고 구체적으로 파키스탄 및 국제사회에 어떠한 영향을 미치는가가 학계의 관심사이다. 본 논문은 문헌연구를 통해 파키스탄의 포퓰리즘조직을 분류하고, 조직구성 및 그들의 테러리즘활동이 미치는 영향을 연구하였다. 극단적 포퓰리즘조직들은 파키스탄의 국내정치환경을 악화시키고 본국의 국제화를 지연시킨다. 이와 더불어 파키스탄의 경제성장발전과 국민생활 수준의 향상을 저해시키고 있다. 또한 주변국가간의 외교관계도 악화시키고 있다는 점도 도출하였다.

A Study on Status Quo and Problems of Cultural Exchange of Bangladesh-China-India-Myanmar Economic Corridor from the Perspective of Soft Power

Sun Xiqin,He Hongmei,Zhou Yunsong,Zhou Yuting 한국정치사회연구소 2019 한국과 국제사회 Vol.3 No.2

소프트 파워는 국제 교류 및 지역 협력에서 중요한 역할을 하고 있다. 방글라데시·중국·인도·미얀마 지역은 지리적으로 보면 서로 인접되어 있으며 역사적으로 왕래가 빈번한다. 2013년 중·인 양국이 방글라데시·중국·인도·미얀마 경제회랑 건설을 제의한 후에, 방글라데시와 미얀마가 이 제안에 적극적으로 호응하면서 4국 간의 교류는 더욱 밀접해진다. 방·중·인·미 경제회랑 지역은 중국 서남과 방글라데시·인도·미얀마를 연결하는 중요한 통로 될 것이고, 이를 통해 관련지역의 문화교류도 많아질 것이다. 하지만 4국 간에는 문화교류는 중국과 인도의 소프트 파워에 의해 불균형한 상태로 보인다. 중국·인도는 방글라데시·미얀마에 대해 문화 제품이 더 많이 수출하고 있고, 이는 많은 분야에서 방글라데시와 미얀마에게 영향을 주고 있다. 향후에 이 경제회랑은 문화교류 및 협력 가속화하는 배경 하에, 지속 가능한 발전 체제를 구축해 나가야하며, 이를 통해 4국의 소프트 파워 영향력을 균형화시켜서 지역문화의 백화제방(百花齐放)를 달성할 것이다. Nowadays, soft power is playing a more important role in international communication and cooperation, and as cultural exchange in regional cooperation is deeply influenced by national soft powers, the development is usually unbalanced. Bangladesh, China, India and Myanmar are adjacent to each other with a long history of intercourse. In the year 2013, initiation of constructing Bangladesh-China-India-Myanmar Economic Corridor advocated by China and India was responded positively by Bangladesh and Myanmar. Since then, the world has witnessed an increasing connection of these four countries. Being the critical bond connecting the southwestern areas of China and Bangladesh, India as well as Myanmar, Bangladesh-China-India-Myanmar Economic Corridor is characterized by multiple regional cultures along with frequent connections in cultural products and activities. However, cultural exchange now is dominated by imbalanced development due to potent soft power of China and India that these two countries export more cultural products to the rest, which has an impact in many fields of Bangladesh and Myanmar. Priority should be given to coordinated development in cultural exchange regarding the construction of Bangladesh-China-India-Myanmar Economic Corridor. Only by developing a sustainable development mechanism for cultural exchange, to coordinate the influences of soft powers of these four countries, then a fine complexion of all flowers are in bloom can be created, returning to five original intention of the construction of this economic corridor: “Policy Communication” and “Strength People-to-people Ties”, etc.

Ensemble learning-based hierarchical retrieval of similar cases for site planning

Wang Pengyue,Guo Maozu,Han Yunsong,Zhao Lingling,Zhou Xiaoping,Zhang Dayu 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.6

Site planning not only involves the arrangement of a large number of elements but also considers the complexity of urban systems; hence, the design process involves large workloads and is time consuming. Retrieving similar existing cases helps architects optimize or accelerate the design process. This paper proposes a computational approach that provides valuable references by retrieving similar cases. Three types of attributes are extracted to represent a given parcel: land-use attributes, geometric attributes (area, orientation, etc.), and environmental attributes (greening rate, surrounding facilities, etc.). The complete hierarchical retrieval process is divided into three phases. The first phase selects cases whose land-use attributes are consistent with the target parcel. Then, the similarity distances between the given target parcel and the selected cases are calculated using geometric attributes. The eXtreme Gradient Boosting (XGBoost) classifier is adopted to determine which case is similar to the target parcel. Finally, similarity scores of the retrieved cases are calculated based on the environmental attributes to provide more options during the actual design. In total, 1189 cases with different land-use types in Beijing were collected for the case base. The comparative experimental results confirmed that the proposed ensemble learning-based hierarchical retrieval of similar cases approach improves the accuracy of retrieval results. Furthermore, we use a real-world target parcel to demonstrate the superiority and flexibility of the retrieval process.