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Heading control strategy assessment for coaxial compound helicopters

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Chinese Journal of Aeronautics 2019年第9期32卷 2037-2046页

作者： Ye YUAN Douglas THOMSON Renliang CHEN Richard dunlop National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics&AstronauticsNanjing 210016China University of Glasgow Glasgow G12 8QQUnited Kingdom

The coaxial compound helicopter has two possible strategies for heading control: collective differential and rudder deflection. A flight dynamics model is developed to assess the effect of different heading control strategies. This includes the trim characteristics, steady flight performance,controllability, and manoeuvrability. The trim study demonstrates that heading control strategies are less influential on trim results, and the steady flight performance is also not significantly affected by the heading control strategy adopted. The controllability analysis shows although heading bandwidth and phase delay results at various speeds with different heading control strategies are all satisfied, the control derivative of the collective differential decreases as speed increases, and its heading aggressive agility is degraded into Level 3 in high-speed flight. In addition, using collective differential would lead to severe heading-rolling coupling as forward speed increases. On the contrary, the control derivative and aggressive agility of the rudder deflection is improved with forward speed, and there is no evidence of heading-rolling coupling. Finally, the transient turn MissionTask-Element(MTE) is utilized to investigate the heading manoeuvre characteristics in different heading control strategies, which indicates that the collective differential would add the amplitude of control input and the power consumption during this MTE.

关键词： Coaxial compound helicopter Control strategy Handling qualities Helicopter flight dynamics Helicopter performance

A new processing method for the AE index

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Science China(Technological Sciences) 2008年第10期51卷 1713-1720页

作者： W. BAUMJOHANN M. dunlop Space Research Institute Austrian Academy of Sciences Graz Austria Space Sciences Division Rutherford Appleton Laboratory Chilton Didcot United Kingdom

In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as a coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index and AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

关键词： AE index Dst index FIR filter substorm

The radial evolution of earthward BBFs during substorm

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Science China Earth Sciences 2010年第10期53卷 1542-1551页

作者： REME H DANDOURAS I LUCEK E dunlop M Centre d'Etude Spatiale des Rayonnements Blackett Laboratory Imperial College London Rutherford Appleton Laboratory

We here study the occurrence rate,probability function of velocity and duration of earthward bursty bulk flows(BBFs) in the Inner Plasma Sheet(IPS,β>0.5) using the data of Cluster in 2001 and *** occurrence rate of earthward BBFs increases with distance from the Earth up to ?19 RE,which is in agreement with the previous observations of the radial evolution of *** 54% of earthward BBFs in expansion phase have a velocity larger than 600 km/s,whereas only 38% of earthward BBFs in growth and recovery phases have a velocity larger than 600 km/*** average velocity of earthward BBFs in expansion phase is 732 km/s,larger than those in growth phase(631 km/s) and recovery phase(617 km/s).The durations of earthward BBFs decrease with the decrease of downtail distance from Earth due to the braking of earthward *** duration of earthward BBFs in expansion phase is larger than that in growth and recovery *** average durations in growth,expansion,and recovery phases are respectively 49.3,71.5,and 47.6 ***,the ratios of transports of energy of earthward BBFs in growth,expansion,and recovery phases can be estimated to be 0.51:1:***,the earthward BBFs in the expansion phase have the largest capability of the transport of energy and can produce the largest braking effects,such as inertial currents and auroral activities.

关键词： substorm growth expansion recovery duration energy transport

Limits of drag augmentation at spacecraft end-of-mission and a mitigation strategy

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Astrodynamics 2021年第2期5卷 109-120页

作者： Emma Kerr malcolm Macdonald University of Strathclyde GlasgowG11XJUK

An increasing number of objects are being launched into low-Earth ***,to avoid the possibility of future in-orbit collisions space object removal techniques are receiving *** one of the most developed techniques,drag augmentation is increasingly being considered as an option for end-of-mission removal of objects from low-Earth *** paper highlights a common misconception around drag augmentation:although it can be used to reduce de-orbit time,when used inappropriately it can increase the volume swept by an object and,thus,increase the occurrence risk of collision with another space *** ignoring this increased risk of collisions could leave spacecraft operators,and consequently their responsible state party,open to liability *** investigating the volume swept and de-orbit lifetime,a strategy of delayed deployment is proposed as a compromise between reducing volume swept and time to ***,this increases system complexity and,likely,cost.

关键词： drag augmentation volume area-time-product space debris liability Learned Hand formula calculus of negligence

ZnO nanofluids-A potential antibacterial agent

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Progress in Natural Science:Materials International 2008年第8期18卷 939-944页

作者： malcolm Povey David York Procter Department of Food Science University of Leeds Leeds LS2 9JT UK Procter and Gamble Newcastle Technical Centre Newcastle-upon-Tyne NE12 9TS UK

In this work, ZnO nanofluids were produced by a medium mill with a pH value of about 7.2 and characterized by Nano-Sizer and SEM. After milling, ZnO nanofluids were formed with an average particle size of 198.4 nm. The ZnO nanofluids used for testing were stored for different periods (1-, 90- and 120-day) and kept in different conditions (under the light and in the dark). The antibacterial activities of these ZnO nanofluids were evaluated by estimating the reduction ratio of the bacteria treated with ZnO. The results showed that the ZnO nanofluid stored for 120 days under the light had the best antibacterial behavior against Escherichia coli DH5a. SEM images suggest that an interaction between the ZnO particles and the E. coli bacteria cells caused by electrostatic forces might be a mechanism.

关键词： Antibacterial Nanofluids ZnO E. coli Photocatalysis

Induction of Root Hair Growth in a Phosphorus-Buffered Culture Solution

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Agricultural Sciences in China 2006年第5期5卷 370-376页

作者： LIU Guo-dong James dunlop Thai Phung Institute of Natural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 P.R. China AgResearch Grasslands Research Center Private Bag 11008 Palmerston North New Zealand

A system to control the release of phosphate in water was successfully established, based on solubility product of [Ca^2＋] and [PO4^3-] using tricalcium phosphate as P source in the hydroponic solution, and adding CaCl2 for supplementing extra Ca^2＋. The system, similar to soil solutions, was a P nutrient buffer solution with very low bioavailable P. The buffer solution induced the roots of both monocotyledon and dicotyledon species to grow abundant root hairs, 3 mm in maximum length. The monocotyledons were corn （Zea mays L.）（var. Yellow Rose）, wheat （Triticum aestivum L.）（var. Yanzhong 144）, Triticale secale L. （vat. Jingsong 5）, and ryegrass （Lolium rigidum L.）（var. Ruanni）, and the dicotyledons were Arabidopsis thaliana L. （var. Columbia）, white clover （Trifolium repens）（var. Kopu）, Lotus （Lotus peduncucatus Cav. Luliginosus Schkuhr）（var. Grasslands Maku）. For these species we proved that the root environment controls the induction of root hair formation. However, the hydroponic buffer solution failed to induce root hairs on the roots of onion （Allium cepa L.）. Other investigators have concluded that corn does not form root hairs in hydroponics, but abundant long root hairs on corn were induced by this buffer system. The roots with abundant long root hairs are called ＂hedgehog roots＂ because they have hairs everywhere just like a hedgehog.

关键词： low-P stress root hairs Arabidopsis thaliana Zea mays Triticum aestivum

Historical imaginaries, historic urban branding, and the local state in China: rejuvenation discourse, manufactured heritage and simulacrascapes

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Built Heritage 2023年第1期7卷 76-87页

作者： Andrew malcolm Law School of Architecture Planning and LandscapeNewcastle UniversityNewcastleUK

This intervention examines the extant literature on historical imaginaries and historic urban branding in *** suggests that while research in this field has increasingly moved away from an economic(or an implicit neo-Marxist)model,there is still a lack of research on the role of broader cultural and state led discourses of nationalism in the construction of historic urban imaginaries and historic urban branding within Chinese *** unpacking one nationalistic discourse a-narrative of rejuvenation-this article argues that more needs to be done to examine the role of these themes in the construction of historical imaginaries at the level of the local state(including related state networks of developers,retailers,tourist officials,town planners,architects,and designers).It is suggested that an analysis of these discourses and imaginaries is important if we are:1)to appreciate the role of these themes in the construction and/or the reconfiguration of existing or emerging historic brands within Chinese cities;2)to comprehend the construction of'authorised heritage discourses,(AHDs)practices and materialities at the level of the local state;3)to understand the politics of the past(including the uses of history,memory,nostalgia,and heritage)at the level of the local state;4)to be aware of the way in which these themes inform the preservation,conservation,and/or the demolition of heritage space at the level of the local state;5)to recognise the manufacture of'heritage'or simulacrascapes within Chinese cities.

关键词： rejuvenation historical urban imaginaries historical urban branding built heritage simulacrascapes

Evolution of Microalloyed Linepipe Steels With Particular Emphasis on the “Near Stoichiometry” Low Carbon,0.10 Percent Niobium “HTP” Concept

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Journal of Iron and Steel Research International 2011年第S1期18卷 652-657页

作者： Gray J.malcolm Microalloyed Steel Institute Inc. 5100 Westheimer Ste 540HoustonTX 77056 USA

Microalloyed linepipe steels were first introduced in 1959 at strength levels around 52-60 ksi [1] [2].The steels were generally strengthened by niobium or vanadium used *** strengths levels increased to X-70 in the early 1970’s niobium and vanadium were used in combination and controlled rolling was introduced on a broad *** strengths decrease tolerance for impurities and non-metallic inclusions which required improved steelmaking ***,carbon,and nitrogen were reduced and continuous casting was increasingly applied which required improved ladle refining and deoxidation ***-molybdenum steels were introduced by IPSCO in 1972 [3] and by Italsider in 1974 [4].Steels with higher niobium contents were also introduced in the early 1970’s but available steelmaking technologies limited the use of optimum niobium to carbon ratios,*** approaching *** the steels benefited from the effect of niobium in retarding austenite recrystallization at relatively high rolling temperatures and they developed attractive combinations of strength and toughness in old manufacturing facilities using simple (relaxed) rolling *** in the price of molybdenum and vanadium in the past decade and expanded application of API Grade X-80 linepipe,have led to more widespread use of niobium contents up to 0.11 percent,in combination with 0.02-0.03 percent carbon (near stoichiometry) thus maximizing the effects of solute niobium during rolling,in lowering transformation temperature,and thereby reducing reliance on other alloying,often expensive,*** history of these developments will be presented and applications of the concept will be summarized.

关键词： HTP Low Carbon,0.10 Percent Niobium Near Stoichiometry Evolution of Microalloyed Linepipe Steels With Particular Emphasis on the Concept

Review on solar sail technology

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Astrodynamics 2019年第2期3卷 93-125页

作者： Shengping Gong malcolm Macdonald School of Aerospace Engineering Tsinghua UniversityBeijing100084China Department of Mechanical&Aerospace Engineering University of StrathclydeGlasgouScotland

This paper reviews solar sail trajectory design and dynamics,attitude control,and structural *** the area of orbital dynamics,methods relevant to transfer trajectory design and non-Keplerian orbit generation are *** the area of attitude control,di erent control strategies,including utilisation of solar radiation pressure and conventional actuators,are ***,the methods of modelling structural dynamics during and after deployment are discussed,before considering possible future trends in developing of solar sailing missions.

关键词： solar sail orbit attitude structure