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1.
In this paper, the hinged road-mat construction is modeled as a cable structure, and based on the equivalent cable theory the sinkage of the roadway is evaluated. Neglecting details of the interaction between tires and road mats, works caused by the traction, resistance, and drawbar pulling are defined to build a new work criterion to evaluate the mobility of vehicles on the hinged road mats. Mobility diagrams, related to coefficient of adhesion, terrain deformation, beam width, and fastening force, are developed to evaluate the locomotion of vehicles and further guide the design of hinged road mats. The presented method compares well with the field terramechanical experiments of the hinged road mats, thus verifying the validity of equivalent cable modeling and work criterion for hinged road mats. 相似文献
2.
K. Zimmermann I. Zeidis M. Pivovarov K. Abaza 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(5):353-362
In this paper we discuss an approximately steady motion of an oscillator as a single whole with a constant “on the average”
velocity. For that purpose we analyze the position and stability of some special points of the phase portrait. In the presence
of internal excitation and nonsymmetric Coulomb dry friction, a motion of the oscillator with a constant “on the average”
velocity is possible. The algebraic equation for this constant velocity is found. For different parameters of the model there
exist at most three regimes of motion with a constant velocity, but only one or two of them are stable. The theoretical results
obtained can be used for the design of worm-like moving robots. 相似文献
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4.
Robot locomotion on rigid terrain or in fluids has been studied to a large extent. The locomotion dynamics on or within soft substrates such as granular material (GM) has not been fully investigated. This paper proposes a hybrid force model to simulate and evaluate the locomotion performance of a legged terrestrial robot in GM. The model incorporates an improved Resistive Force Theory (RFT) model and a failure-based model. The improved RFT model integrates the force components of individual leg elements over the curved leg portion submerged in GM at any moment during a full period of leg rotation. The failure-based model is applied in a bar drag model to yield the normal and the lateral forces of the individual RFT elements as functions of the locomotion depth and speed. The hybrid model is verified by the coincidence between the theoretical predictions and the experimental results. The hybrid model is used to analyze the effects of angular velocity and leg shape with high precision and can guide the design of the legs with any profiles. Our study reveals that the interactions between locomotor and substrate are determined by the locomotor structural characteristics, the nature of the substrate, and the control strategy. 相似文献
5.
Beatrice Malgesini Eduard Felder Nicola Mongelli Gianluca Papeo 《Molecular diversity》2009,13(1):53-56
Polyfluorinated N-α-Fmoc--Boc-l-lysine represents the best-in-class among a set of polyfluorinated amino acids (PFAs) which are useful tools for 19F NMR-Based Screening. In this communication, optimized reaction conditions that allowed for the multi-gram preparation of
this unnatural amino acid are reported. 相似文献
6.
Hideyoshi Abe Akira Kenmoku Noriyuki Yamaguch Kenjiro Hattori 《Journal of inclusion phenomena and macrocyclic chemistry》2002,44(1-4):39-47
Bi-galactose-branched cyclodextrins (Bi-Gal-CDs)(1–6) having different spacer arm lengths between two terminal galactoses were foundto have the optimum length for association with PNA lectin. Also, the inclusioninteraction of the drug depended on the length of the spacer arms. The dual association of thesecompounds was quantitatively evaluated by SPR and compared to the other oligosaccharide-branchedCDs (Scheme 1). The number and the length of the spacer arm are important for theassociation both with the lectin and drug for the purpose of targeting drug-delivery systems.The association constants K of bi-Gal-CD (2) with rat liver cells showed a 60 timeshigher association than with PNA. Direct evidence of the association between PNA andbi-Gal-CD (2) was characterized by AFM observations. The results obtained strongly suggested a method to find a new design for the targeting drug carrier. In order toincrease the association with the cell, a sufficient spacer arm length is necessary for the effectivedual recognition of the oligosaccharide-CDs. In order to increase the inclusion of thedrug, the CD structure of a multi-saccharide branch is necessary. 相似文献
7.
Odinokov V. N. Spivak A. Yu. Emel"yanova G. A. Kutepov B. I. 《Russian Chemical Bulletin》2002,51(3):526-530
The reactions of trimethylhydroquinone with isoprenoid allylic alcohols catalyzed by a Pentasil type zeolite in the H-form gave trimethyl-1,4-benzoquinones with the corresponding isoprenoid group, which were subsequently transformed into the target 3-chromenes on treatment with pyridine. Partial ozonolysis of chromenes proceeded selectively at the -bond of the side chain, resulting in the corresponding chromenes with an -carbonyl group. 相似文献
8.
General mechanical considerations provide an upper bound for the take-off velocity of any jumper, animate or inanimate, rigid or soft body, animal or vegetal. The take-off velocity is driven by the ratio of released energy to body mass. Further, the mean reaction force on a rigid platform during push-off is inversely proportional to the characteristic size of the jumper. These general considerations are illustrated in the context of Alexander's jumper model, which can be solved exactly and which shows an excellent agreement with the mechanical results. 相似文献
9.
This paper describes both the hardware and software development of three custom made wireless systems used for the interactive synthesis of footstep sounds. The data collected from the detection of the feet movements of a walker are used for real-time control of physical models for the auditory display of different ground textures and shoe types. The first system is based on a wooden plank under which an array of microphones is placed. The second system exploits the motion capture technology. The third system consists of a pair of sandals enhanced with two force sensitive resistors and two 3-axes accelerometers for each shoe. The characteristics of the three architectures are discussed and compared. The developed locomotion interfaces find application in several contexts, such as augmented reality, virtual reality, or entertainment, as well as in perceptual studies investigating the influence of interactive sounds on locomotion performance usable for training and rehabilitation purposes. 相似文献
10.
F. Alouges A. DeSimone A. Lefebvre 《The European physical journal. E, Soft matter》2009,28(3):279-284
We present a theory for low-Reynolds-number axisymmetric swimmers and a general strategy for the computation of strokes of
maximal efficiency. An explicit equation characterizing optimal strokes is derived, and numerical strategies to obtain solutions
are discussed. The merits of this approach are demonstrated by applying it to two concrete examples: the three linked spheres of Najafi and Golestanian and the pushmepullyou of Avron, Kenneth, and Oakmin. 相似文献