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Dynamical Janssen effect on granular packing with moving walls 总被引:1,自引:0,他引:1
Apparent mass (M(app)) measurements at the bottom of granular packings inside a vertical tube in relative motion are reported. They demonstrate that Janssen's model is valid over a broad range of velocities v. The variability of the measurements is lower than for static packings and the theoretical exponential increase of M(app) with the height of the packing is precisely followed (the corresponding characteristic screening length is of the order of the tube diameter). The limiting apparent mass at large heights is independent of v and significantly lower than the static value. 相似文献
153.
Fluorescence recovery after pattern photobleaching is used to measure the self-diffusion of surfactant molecules, along cylinders and perpendicular to their main axis in an oriented hexagonal lyotropic phase. Unexpectedly, while the motion along cylinders is diffusive, a superdiffusive behavior is observed in the direction perpendicular to the cylinder axis. Moreover, varying the lattice parameter, we found that the perpendicular diffusion time is governed only by the number of cylinders to cross, providing experimental evidence for superdiffusion with a bounded step length. 相似文献
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Bifurcation Analysis of a Predator–Prey System with Generalised Holling Type III Functional Response
Yann Lamontagne Caroline Coutu Christiane Rousseau 《Journal of Dynamics and Differential Equations》2008,20(3):535-571
We consider a generalised Gause predator–prey system with a generalised Holling response function of type III: . We study the cases where b is positive or negative. We make a complete study of the bifurcation of the singular points including: the Hopf bifurcation
of codimensions 1 and 2, the Bogdanov–Takens bifurcation of codimensions 2 and 3. Numerical simulations are given to calculate
the homoclinic orbit of the system. Based on the results obtained, a bifurcation diagram is conjectured and a biological interpretation
is given.
相似文献
158.
The chemical constituents isolated from every stage of the Taiwanese swallowtail butterfly, Pachliopta aristolochiae interpositus, were studied and compared with the constituents of the insect feeding plant, A. cucurbitifolia. Two aristolochic acid derivatives ( 1 and 4 ) and three aristolactam analogues ( 5, 6 , and 7 ) were isolated from the larval osmeterial fluid and larvae of the insect. In addition, four purines ( 2, 3, 13 , and 14 ), one indole alkaloid ( 11 ), one steroid ( 10 ), two benzenoids ( 8 and 9 ) and allantoin ( 12 ) were also isolated from the insect. Among these compounds, aristolochic acid ‐I (AA‐I, 1 ) was detected in all life stages of the insect, especially in the larval osmeterial fluid. The studies confirm that the toxic AAs are used as larval feeding stimulants and deterrent allomones against birds. 相似文献
159.
Dr. Marinela M. Dîrtu France Schmit Dr. Anil D. Naik Dr. Ionela Rusu Prof. Dr. Aurelian Rotaru Sergej Rackwitz Dr. Juliusz A. Wolny Prof. Dr. Volker Schünemann Prof. Dr. Leonard Spinu Prof. Dr. Yann Garcia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5843-5855
A thermochromic 1D spin crossover coordination (SCO) polymer [Fe(βAlatrz)3](BF4)2 ? 2 H2O ( 1? 2 H2O), whose precursor βAlatrz, (1,2,4‐triazol‐4‐yl‐propionate) has been tailored from a β‐amino acid ester is investigated in detail by a set of superconducting quantum interference device (SQUID), 57Fe Mössbauer, differential scanning calorimetry, infrared, and Raman measurements. An hysteretic abrupt two‐step spin crossover (T1/2↓=230 K and T1/2↑=235 K, and T1/2↓=172 K and T1/2↑=188 K, respectively) is registered for the first time for a 1,2,4‐triazole‐based FeII 1D coordination polymer. The two‐step SCO configuration is observed in a 1:2 ratio of low‐spin/high‐spin in the intermediate phase for a 1D chain. The origin of the stepwise transition was attributed to a distribution of chains of different lengths in 1? 2 H2O after First Order Reversal Curves (FORC) analyses. A detailed DFT analysis allowed us to propose the normal mode assignment of the Raman peaks in the low‐spin and high‐spin states of 1? 2 H2O. Vibrational spectra of 1? 2 H2O reveal that the BF4? anions and water molecules play no significant role on the vibrational properties of the [Fe(βAlatrz)3]2+ polymeric chains, although non‐coordinated water molecules have a dramatic influence on the emergence of a step in the spin transition curve. The dehydrated material [Fe(βAlatrz)3](BF4)2 ( 1 ) reveals indeed a significantly different magnetic behavior with a one‐step SCO which was also investigated. 相似文献
160.
Dr. Yann Odabachian Dr. Qian Wang Prof. Dr. Jieping Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12229-12233