Yichen Zhang, Feng Cui, Wu Liu, Wenhao Zhu, Yiming Xiao, Qingcheng Guo and Jiawang Mou
Endurance time is an important factor limiting the progress of flapping-wing aircraft. In this study, this paper developed a prototype of a double-wing flapping-wing micro air…
Abstract
Purpose
Endurance time is an important factor limiting the progress of flapping-wing aircraft. In this study, this paper developed a prototype of a double-wing flapping-wing micro air vehicle (FMAV) that mimics insect-scale flapping wing for flight. Besides, novel methods for optimal selection of motor, wing length and battery to achieve prolonged endurance are proposed. The purpose of this study is increasing the flight time of double-wing FMAV by optimizing the flapping mechanism, wings, power sources, and energy sources.
Design/methodology/approach
The 20.4 g FMAV prototype with wingspan of 21.5 cm used an incomplete gear flapping wing mechanism. The motor parameters related to the lift-to-power ratio of the prototype were first identified and analyzed, then theoretical analysis was conducted to analyze the impact of wing length and flapping frequency on the lift-to-power ratio, followed by practical testing to validate the theoretical findings. After that, analysis and testing examined the impact of battery energy density and efficiency on endurance. Finally, the prototype’s endurance duration was calculated and tested.
Findings
The incomplete gear facilitated 180° symmetric flapping. The motor torque constant showed a positive correlation with the prototype’s lift-to-power ratio. It was also found that the prototype achieved the best lift-to-power ratio when using 100 mm wings.
Originality/value
A gear-driven flapping mechanism was designed, capable of smoothly achieving 180° symmetric flapping. Besides, factors affecting long-duration flight – motor, wings and battery – were identified and a theoretical flight duration analysis method was developed. The experimental result proves that the FMAV could achieve the longest hovering time of 705 s, outperforming other existing research on double-wing FMAV for improving endurance.
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Lin Gaorui, Wang Fei and Mi Qingzhi
The Qingcheng County, where the ancient city wall is located, has rich regional cultural heritage. This ancient city wall is an important symbol for exhibiting the regional…
Abstract
The Qingcheng County, where the ancient city wall is located, has rich regional cultural heritage. This ancient city wall is an important symbol for exhibiting the regional historical culture of Qingcheng. However, urban expansionary construction activities, environment chaos, and other issues have led to the destruction of the main part of the Qingcheng Ancient City Wall. Previous strategies for historical and cultural heritage Preservation planning emphasize rigidity and disregard resilience in protecting cultural heritage and the environment. On the basis of an analysis of the built environment of the Qingcheng Ancient City Wall, this study gains insights into the three aspects, namely, land use, road traffic, and municipal and disaster prevention in frastructure of the old city proper where the ancient city wall is located. A planning strategy that integrates an ordered control of land development, highly efficient and compound road traffic, synergetic municipal administration, and sound disaster-preventing infrastructure is formed according to cognitive results.
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Xiaohui Yu, Fei Wang and Lina Wang
City wall is an important symbol of ancient Chinese cities with unique geographical and cultural characteristics. Thus, the preservation of this historic landmark is considered…
Abstract
City wall is an important symbol of ancient Chinese cities with unique geographical and cultural characteristics. Thus, the preservation of this historic landmark is considered significantly important. However, numerous residential construction activities and changes in ecological environment have destructed a great portion of the city walls in recent years. This study looks into the preservation of the ancient city walls from the systematic perspective and in line with the actual characteristics of Longdong Region to provide guideline measures for the protection and restoration of such landmark. Cognition and preservation are adopted extensively to investigate the specific situation of and the factors that influence the ancient city walls in this region. Preservation strategies for the city walls, including the “Axis-Point” system, planning control, and authenticity readability, are presented. The ancient city walls in Longdong Region can be preserved by protecting the entire region, the city, and the main wall body. The systematic method and preservation strategies at the “macro perspective,” “medium perspective” and “micro perspective” levels can solve the preservation problems of the ancient city walls in Longdong Region effectively.
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The purpose of this paper is to discuss some of the main UNESCO sites in China. The cases under study offer some insight into the complexity of the management of Chinese cultural…
Abstract
Purpose
The purpose of this paper is to discuss some of the main UNESCO sites in China. The cases under study offer some insight into the complexity of the management of Chinese cultural organizations, as well as the problem of the presentation of China's heritage in a new global context.
Design/methodology/approach
The paper is based on field research in 2008/2009 on the Chinese sites on UNESCO's World Heritage List (WHL). While details of the research will be provided in a later stage, some interesting findings and patterns are emerging.
Findings
Building on the evidence of several case studies, a preliminary evaluation of the costs, the benefits and the negative outcomes of the listing process is presented in the second section. In a nutshell, the process appears to be increasingly expensive for local government and, despite the expectations for successful inscription onto the WHL, results in terms of increased tourism income are not always guaranteed. On the one hand, being listed raises the awareness of heritage protection among the general public but, on the other, there are also risks connected to tourism overexploitation.
Originality/value
From a methodological point of view the study points out the scarce quality of basic data regarding visitors and financial issues among Chinese World Heritage sites. This is particularly critical for sustainable development if it is considered that a World Heritage site should be accountable to the international audience. In the final section of the paper some open questions concerning sites' management models are presented.