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Effectiveness of a Passive-active Vibration Isolation System with Actuator Constraints

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Chinese Journal of Mechanical Engineering 2014年第3期27卷 567-574页

作者： SUN Lingling SUN Wei SONG Kongjie HANSEN colin H Key Laboratory of High-efficiency and Clean Mechanical Manufacture Shandong University School of Mechanical Engineering University of Adelaide

In the prediction of active vibration isolation performance, control force requirements were ignored in previous work. This may limit the realization of theoretically predicted isolation performance if control force of large magnitude cannot be supplied by *** behavior of a feed-forward active isolation system subjected to actuator output constraints is investigated. Distributed parameter models are developed to analyze the system response, and to produce a transfer matrix for the design of an integrated passive-active isolation system. Cost functions comprising a combination of the vibration transmission energy and the sum of the squared control forces are proposed. The example system considered is a rigid body connected to a simply supported plate via two passive-active isolation mounts. Vertical and transverse forces as well as a rotational moment are applied at the rigid body, and resonances excited in elastic mounts and the supporting plate are analyzed. The overall isolation performance is evaluated by numerical simulation. The simulation results are then compared with those obtained using unconstrained control strategies. In addition, the effects of waves in elastic mounts are analyzed. It is shown that the control strategies which rely on tmconstrained actuator outputs may give substantial power transmission reductions over a wide frequency range, but also require large control force amplitudes to control excited vibration modes of the system. Expected power transmission reductions for modified control strategies that incorporate constrained actuator outputs are considerably less than typical reductions with unconstrained actuator outputs. In the frequency range in which rigid body modes are present, the control strategies can only achieve 5-10 dB power transmission reduction, when control forces are constrained to be the same order of the magnitude as the primary vertical force. The resonances of the elastic mounts result in a notable increase of

关键词： passive-active isolation transfer matrix control effort constraint feedforward control

Assessment of robustness of structures:Current state of research

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Frontiers of Structural and Civil Engineering 2013年第4期7卷 356-368页

作者： colin BrETT Yong LU Institute for Infrastructure and Environment School of Engineeringthe University of EdinburghEdinburgh EH89YLUK

The concept of structural robustness and relevant design guidelines have been in existence in the progressive collapse literature since the 1970s following the partial collapse of the ronan Point apartment building;however,in the more general context,research on the evaluation and enhancement of structural robustness is still relatively *** paper is aimed to provide a general overview of the current state of research concerning structural *** focus is placed on the quantification and the associated evaluation methodologies,rather than specific measures to ensure prescriptive robustness *** associated concepts,such as redundancy and vulnerability,will be discussed and interpreted in the general context of robustness such that the corresponding methodologies can be compared quantitatively using a comparable scale.A framework methodology proposed by the authors is also introduced in line with the discussion of the literature.

关键词： structural robustness abnormal exposure vulnerability collapse consequence

recent advances in wheel–rail rCF and wear testing

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摩擦:英文版 2023年第12期11卷 2181-2203页

作者： Sundar SHrESTHA Maksym SPIrYAGIN Esteban BErNAL Qing WU colin COLE Centre for railway Engineering Central Queensland UniversityRockhampton 4701Australia Australasian Centre for rail Innovation Canberra 2601Australia

The wear and rolling contact fatigue (rCF) testing approaches for wheels and rails have been reviewedand evaluated in this study. The study points out the advantages and limitations of the existing approaches. Thebroad analysis revealed that scaled laboratory-based wear testing is widely applied. However, it is necessary topredetermine the input parameters and observing parameters for scaled wear testing for three reasons: first, toemulate the real-world scenarios as closely as possible;second, to postprocess the results received from the scaledtesting and transfer them into real practice at full scale;third, to present the results in a legible/appropriate ***, most of the important parameters required for wear testing have been discussed with fundamental andsystematic explanations provided. Additionally, the transition of the parameters from the real-world into the testdomain is explained. This study also elaborates on the challenges of the rCF and wear testing processes andconcludes by providing major considerations toward successful testing.

关键词： wear testing rolling contact fatigue(rCF)testing wheel-rail

A Comparative Analysis of Four Kinds of Polysaccharides Purified from Furcellaria lumbricalis

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Journal of Ocean University of China 2007年第1期6卷 16-20页

作者： BArrOW colin Ocean Nutrition Canada Ltd. Dartmouth Nova Scotia B2Y 4T6 Canada

Four kinds of polysaccharides (FA, FB, FC and FD) were extracted and purified from a red alga Furcellaria lumbri-calis. Their monosaccharide composition, average molecular mass (Mw) and structural feature were determined by gas chromatog-raphy (GC), high performance gel permeation chromatography (HPGPC) and Fourier transform infrared spectroscopy (FTIr), respectively. The results showed that FA and FB were composed of galactose (Gal), 3,6-anhydro-galactose (AnG) and 4-sulfated-galactose (G4S), which were structurally similar to β-carrageenan and κ-carrageenan. FC was composed of sulfated galactose and small amount of AnG, indicating that it was a hybrid-sulfated galactan. FD was composed of α-1, 4-glucose and belonged to floridean starch. The respective yields of FA, FB, FC and FD were 4.84%,33.74%,8.76% and 13.5%, and the cor-responding Mw were 537 kD, 432 kD, 513 kD and 51 kD respectively. Owning to its high content ( >60%) of polysaccharide, F. lumbricalis will be a good source of marine sulfated polysaccharide and shows its potential utilization in food and medicine.

关键词： Furcellaria lumbricalis sulfated galactan carrageenan floridean starch

CLE and rGF Family Peptide Hormone Signaling in Plant Development

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Molecular Plant 2012年第6期5卷 1173-1175页

作者： colin D. Leasure Zheng-Hui He Department of Biology 1600 Holloway Avenue San Francisco State University San Francisco CA 94132 USA

Since the discovery of Systemin in tomatoes in 1991, many additional peptide hormones have been discovered in plants. Plant peptide hormones typically start as small precursor pro- teins （-100a.a.）, which include N-terminal secretory or anchor sequences, and are post-translationally processed into a smaller hormonally active peptide （on the range of 5-18 a.a.）. To date, peptide hormones have been shown to have diverse functions in plants, including nearly every aspect of develop- ment and morphogenesis. Here, we discuss recent reports regarding the CLV3/ESr-rELATED （CLE） and rOOT GrOWTH FACTOr （rGF） families of peptide hormones.

关键词： ArABIDOPSIS GENES

Ecological Status and Uses of Juniper Species in the Cold Desert Environment of the Lahaul Valley, North-western Himalaya, India

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Journal of Mountain Science 2012年第5期9卷 676-686页

作者： Yashwant S.rAWAT colin S.EVErSON School of Agricultural Earth and Environmental SciencesUniversity of KwaZulu-Natal

The juniper species Juniperus polycarpos C. Koch, J. indica Bertol. and J. communis L. var. saxatilis （Pallas） are important elements of the forest vegetation in Lahaul valley in the north-western Himalaya. Their ability to grow under the barren and xeric conditions of cold deserts makes them particularly suited for afforestation programmes under these eeologieal conditions. In the Lahaul valley, juniper species are used as subsistence resources and for religious purposes. Excessive removal of juniper wood and leaves by the local population, overgrazing, habitat fragmentation and low regeneration potential are the main obstacles to eonservation of juniper forests in this region. The present study was carried out to assess density, basal area and importance value index （WI） of the local vegetation as well as uses and amounts of juniper wood and leaves removed from the local forests. Pressure on relict juniper forests due to grazing animals and intensive removal of wood and leaves by the loeal population was found to be greater at an altitude above 3,00o m. The results of the study demonstrated that the different juniper speeies were adapted to specific altitude ranges. A higher species density was recorded at lower altitude except for J. indica which was only present at high altitude （〉3,200 m） on south-facing slopes. Density, basal area and IVI of J. polycarpos were higher at Hinsa （2,7oo m） than at Jahlma （3,000 m）. The rapid loss of vegetation due to overuse and habitat degradation has made the eonservation of juniper forests an important priority in the Lahaul valley. J. polycarpos at loweraltitude and J. indica at higher altitude are ecologically the more suitable species for the successful implementation of conservation programmes. The support of rehabilitation programmes by regional authorities is essential for the reestablishment of the local juniper forests.

关键词： Juniper Distribution Utilization Pattern Agroforestry Forest Conservation

Availability and Use of Willow Species in representative Cold Desert Areas of Northwestern Himalaya,India

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Journal of Mountain Science 2013年第3期10卷 472-481页

作者： Yashwant S.rAWAT colin S.EVErSON Centre for Water resources research School of AgriculturalEarth and Environmental SciencesUniversity of KwaZuluNatal

Willow species （Salix fragilis L. and S. alba L.） are important elements of cold desert agroforestry systems in the Lahaul valley, north- western Himalaya. Their ability to grow through shoot-cuttings plantations under extreme and xeric climatic conditions of cold deserts, makes them ecologically suited and socially accepted for forestry programmes. Willow species in cold deserts may combat desertification and can thrive well in these areas as compared to any other species. Salixfragilis L. and S. alba L. are under cultivation in the Lahaul valley. However, S. fragilis is widely cultivated under the agroforestry and plantation forestry systems. In the Lahaul valley, willow species are used as subsistence resources and for socio-religious purposes. The present study was carried out to examine the vegetation analysis, density, diversity and distribution of willow species, present status and potential willow plantation sites and uses. The results of present study revealed that a higher species density was recorded at middle altitude villages （Jahlma-3,ooo m asl and Hinsa-2,7oo m asl）, except, a higher density of S. fragilis was at Khoksar （3,200 m asl） in plantation forestry on south-facing slopes. In forests, S. fragilis was planted mainly along the water channels, resulted a low density. The shrubby willow species occurred naturally in the entire Lahaul valley up to an altitude of 3,850 m asl. 81% of households felt the scarcity of willow trees, whereas, 19% of households were satisfied with the willow trees they owned. The majority of willow species were planted in middle altitudes on privately owned irrigated lands. It was rated most potential prospective willow planting siteby the farmers. Small size of land-holdings was one of the main constraints for establishing a large number of willow plantations. Commercial aspects of willow species need to be investigated to encourage the farmers to plant more willows further.

关键词： Willow Agroforestry Forestry Speciesdiversity Himalaya

Improved bridge pier collar for reducing scour

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International Journal of Sediment research 2022年第1期37卷 37-46页

作者： Christopher Valela colin David rennie Ioan Nistor Department of Civil Engineering University of Ottawa

This study performed a bridge pier collar comparison for the purpose of reducing scour,while introducing a new collar *** new collar,referred to as Collar Prototype Number 3,was designed based on an equilibrium scour hole and provides a method of controlling the horseshoe *** modelling was utilized to show the flow field and bed shear stress as a result of using Collar Prototype Number 3.A prototype model of Collar Prototype Number 3 and a flat plate collar were constructed for the purpose of comparing both experimentally under different flow *** Prototype Number 3 proved to be an effective device as it reduced scour in terms of the maximum depth downstream of the pier and overall volume,in some instances,by up to 69.7%and 75.7%,***,Collar Prototype Number 3 outperformed the flat plate collar,especially because,unlike the flat plate collar,Collar Prototype Number 3 did not experience undermining.

关键词： Bridge pier Scour Horseshoe vortex Pier collar Scour countermeasure

Clay mineral records of East Asian monsoon evolution during late Quaternary in the southern South China Sea

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Science China Earth Sciences 2005年第1期48卷 84-92页

作者： C.colin A.Trentesaux D.Blamart FrE 2566 Orsaylerre UMR PBDS du CNRSLaboratoire des Sciences du Climat et de I'Environnement Université de Paris XI91405 OrsayFranceUniversite de Lille I59655 Villeneuve d'AscqFranceLaboratoire mixte CNRS-CEA91198 Gif-sur-YvetteFrance

High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 190 ka during late Quaternary from core MD01-2393 off the Mekong river in the southern South China Sea are reported to reconstruct a history of East Asian monsoon *** dominating clay mineral components indicate a strong glacial-interglacial cyclicity, with high glacial illite, chlorite, and kaolinite contents and high interglacial smectites content. The provenance analysis indicates the direct input of clay minerals via the Mekong river drainage *** and chlorite derived mainly from the upper reach of the Mekong river, where physical erosion of meta-sedimentary rocks is dominant. Kaolinite derived mainly from active erosion of inhered clays from reworked sediments in the middle reaches. Smectites originated mainly through bisiallitic soils in the middle to lower reaches of the Mekong river. The smectites/(illite+chlorite)and smectites/kaolinite ratios are determined as mineralogical indicators of East Asian monsoon variations. relatively high ratios occur during interglacials and indicate strengthened summer-monsoon rainfall and weakened winter-monsoon winds; relatively lower ratios happened in glacials, indicating intensified winter monsoon and weakened summer monsoon. The evolution of the summer and winter monsoons provides an almost linear response to the summer insolation of the Northern Hemisphere, implying an astronomical forcing of the East Asian monsoon evolution.

关键词： clay minerals, East Asian monsoon, late Quaternary, Mekong river, South China Sea.