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排序方式: 共有273条查询结果,搜索用时 15 毫秒
1.
Announcements
Preliminary course programme international centre for mechanical Sciences 相似文献2.
Sabeha Yala Mahfoud Boustta Olivier Gallet Mathilde Hindié Franck Carreiras Hamanou Benachour Djahida Sidane Hafit Khireddine 《Journal of materials science. Materials in medicine》2016,27(9):140
A novel synthetic method to synthesize hydroxyapatite/poly (D,L) lactic acid biocomposite is presented in this study by mixing only the precursors hydroxyapatite and (D,L) LA monomer without adding neither solvent nor catalyst. Three compositions were successfully synthesized with the weight ratios of 1/1, 1/3, and 3/5 (hydroxyapatite/(D,L) lactic acid), and the grafting efficiency of poly (D,L) lactic acid on hydroxyapatite surface reaches up to 84?%. Scanning electron microscopy and Fourier transform infrared spectroscopy showed that the hydroxyapatite particles were successfully incorporated into the poly (D,L) lactic acid polymer and X ray diffraction analysis showed that hydroxyapatite preserved its crystallinity after poly (D,L) lactic acid grafting. Differential scanning calorimetry shows that Tg of hydroxyapatite/poly (D,L) lactic acid composite is less than Tg of pure poly (D,L) lactic acid, which facilitates the shaping of the composite obtained. The addition of poly (D,L) lactic acid improves the adsorption properties of hydroxyapatite for fibronectin extracellular matrix protein. Furthermore, the presence of poly (D,L) lactic acid on hydroxyapatite surface coated with fibronectin enhanced pre-osteoblast STRO-1 adhesion and cell spreading. These results show the promising potential of hydroxyapatite/poly (D,L) lactic acid composite as a bone substitute material for orthopedic applications and bone tissue engineering. 相似文献
3.
CPG-based control of a turtle-like underwater vehicle 总被引:1,自引:0,他引:1
This paper presents biologically inspired control strategies for an autonomous underwater vehicle (AUV) propelled by flapping
fins that resemble the paddle-like forelimbs of a sea turtle. Our proposed framework exploits limit cycle oscillators and
diffusive couplings, thereby constructing coupled nonlinear oscillators, similar to the central pattern generators (CPGs)
in animal spinal cords. This paper first presents rigorous stability analyses and experimental results of CPG-based control
methods with and without actuator feedback to the CPG. In these methods, the CPG module generates synchronized oscillation
patterns, which are sent to position-servoed flapping fin actuators as a reference input. In order to overcome the limitation
of the open-loop CPG that the synchronization is occurring only between the reference signals, this paper introduces a new
single-layered CPG method, where the CPG and the physical layers are combined as a single layer, to ensure the synchronization
of the physical actuators in the presence of external disturbances. The key idea is to replace nonlinear oscillators in the
conventional CPG models with physical actuators that oscillate due to nonlinear state feedback of the actuator states. Using
contraction theory, a relatively new nonlinear stability tool, we show that coupled nonlinear oscillators globally synchronize
to a specific pattern that can be stereotyped by an outer-loop controller. Results of experimentation with a turtle-like AUV
show the feasibility of the proposed control laws. 相似文献
4.
Julien Fleureau Karim Bensalah Denis Rolland Olivier Lavastre Nathalie Rioux-Leclercq François Guillé Jean-Jacques Patard Renaud de Crevoisier Lotfi Senhadji 《Expert systems with applications》2011,38(11):14301-14306
In this study, we propose to evaluate the potential of Raman spectroscopy (RS) to assess renal tumours at surgery. Different classes of Raman renal spectra acquired during a clinical protocol are discriminated using support vector machines classifiers. The influence on the classification scores of various preprocessing steps generally involved in RS are also investigated and evaluated in the particular context of renal tumour characterization. Encouraging results show the interest of RS to evaluate kidney cancer and suggest the potential of this technique as a surgical assistance during partial nephrectomy. 相似文献
5.
Jean-Jacques Hébrard 《Information Processing Letters》2003,88(4):177-182
We give a new algorithm for computing a prepositional Horn CNF formula given the set of its models. Its running time is O(|R|n(|R|+n)), where |R| is the number of models and n that of variables, and the computed CNF contains at most |R|n clauses. This algorithm also uses the well-known closure property of Horn relations in a new manner. 相似文献
6.
Emmanuel Benoist Jean-Jacques Hébrard 《Annals of Mathematics and Artificial Intelligence》2003,37(3):251-272
The enlarged Horn formulas generalize the extended Horn formulas introduced by Chandru and Hooker (1991). Their satisfying truth assignments can be generated with polynomial delay. Unfortunately no polynomial algorithm is known for recognizing enlarged Horn formulas or extended Horn formulas. In this paper we define the class of simple enlarged Horn formulas, a subclass of the enlarged Horn formulas, that contains the simple extended Horn formulas introduced by Swaminathan and Wagner (1995). We present recognition algorithms for the simple enlarged Horn formulas and the simple extended Horn formulas whose complexity is bounded by the complexity of the arborescence-realization problem. 相似文献
7.
Models of cortical neuronal circuits commonly depend on inhibitory feedback to control gain, provide signal normalization, and selectively amplify signals using winner-take-all (WTA) dynamics. Such models generally assume that excitatory and inhibitory neurons are able to interact easily because their axons and dendrites are colocalized in the same small volume. However, quantitative neuroanatomical studies of the dimensions of axonal and dendritic trees of neurons in the neocortex show that this colocalization assumption is not valid. In this letter, we describe a simple modification to the WTA circuit design that permits the effects of distributed inhibitory neurons to be coupled through synchronization, and so allows a single WTA to be distributed widely in cortical space, well beyond the arborization of any single inhibitory neuron and even across different cortical areas. We prove by nonlinear contraction analysis and demonstrate by simulation that distributed WTA subsystems combined by such inhibitory synchrony are inherently stable. We show analytically that synchronization is substantially faster than winner selection. This circuit mechanism allows networks of independent WTAs to fully or partially compete with other. 相似文献
8.
S. Grigorescu M. Hindié E. Axente F. Carreiras K. Anselme J. Werckmann I. N. Mihailescu O. Gallet 《Journal of materials science. Materials in medicine》2013,24(7):1809-1821
Laser direct write techniques represent a prospective alternative for engineering a new generation of hybrid biomaterials via the creation of patterns consisting of biological proteins onto practically any type of substrate. In this paper we report on the characterization of fibronectin features obtained onto titanium substrates by UV nanosecond laser transfer. Fourier-transform infrared spectroscopy measurements evidenced no modification in the secondary structure of the post-transferred protein. The molecular weight of the transferred protein was identical to the initial fibronectin, no fragment bands being found in the transferred protein’s Western blot migration profile. The presence of the cell-binding domain sequence and the mannose groups within the transferred molecules was revealed by anti-fibronectin monoclonal antibody immunolabelling and FITC-Concanavalin-A staining, respectively. The in vitro tests performed with MC3T3-E1 osteoblast-like cells and Swiss-3T3 fibroblasts showed that the cells’ morphology and spreading were strongly influenced by the presence of the fibronectin spots. 相似文献
9.
Lucas Jégo Daniel Milési Jean-Jacques Robin Christine Joly-Duhamel 《Polymer Engineering and Science》2020,60(1):95-103
The photocrosslinking of thick samples of 5-ethylidene-2-norbornene–ethylene propylene diene monomer (ENB-EPDM) under air at room temperature was investigated. First, a model study was carried out on low-molecular weight oligomers: squalene, 1,2-polybutadiene, and 1,4-polybutadiene. Several crosslinking agents (meth(acrylics), bismaleimide, and thiol) combined with various photoinitiators were tested to improve the reactivity of these oligomers under UV irradiation. Gel contents, crosslinking densities, viscosities, and viscoelastic properties were measured in order to characterize the extent of crosslinking. Acrylate-based crosslinking agents appeared to be the most reactive species and these results were then applied to a low-molecular weight EPDM. Several photoinitiators were tested and benzophenone turned out to be the most efficient photoinitiator when combined with trimethylolpropane triacrylate. Finally, a commercial EPDM was subsequently photocrosslinked and high gel content and crosslinking density were obtained after only 2 min of irradiation. POLYM. ENG. SCI., 60:95–103, 2020. © 2019 Society of Plastics Engineers 相似文献
10.
Jean-Pierre Martins Louis Doceul Sbastien Marol Elise Delchi Jean-Jacques Cordier Bruno Levesy Alessandro Tesini Emanuela Ciattaglia Richard Tivey Ren Gillier Christophe Abbes 《Fusion Engineering and Design》2009,84(7-11):1268-1275
In the field of the ITER port plug engineering and integration task, CEA has contributed to define proposals concerning the port plugs vacuum sealing interface with the vessel flange and the equatorial plug handling.The 2001 baseline vacuum flange sealing consisted of TIG welding of a 316L strip plate on to U shapes. This arrangement presented some issues like welding access, implementation of tools, lip consumption, complex local leak test, continuous leak checking. Therefore, an alternate sealing solution based on the use of metallic gaskets is proposed. The different technical aspects are discussed to explain how this design can simplify the maintenance and deal with safety and vacuum requirements.The design of the mechanical attachment and vacuum sealing of the plug has constantly evolved, but the associated remote handling equipment was not systematically reviewed. An update of the cask and maintenance procedure was studied in order to design it in accordance with the last generic plug flange design. This includes a concept of a gripping system that uses the plug flange bolting area and, to help the remote handling process, a cantilever assisting system is suggested to increase the reliability of the transfer operation between vacuum vessel and cask. 相似文献