排序方式: 共有49条查询结果,搜索用时 15 毫秒
11.
This paper presents a constructive variant of acoustic impedance tube used to determine the coefficient of sound absorption materials. This alternative design brings a contribution in terms of the number of microphones mounted on the tube impedance control of acoustic vibration generator, with the calibration system of microphones mounted on the device. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
We study global minimizers of a continuum Landau–De Gennes energy functional for nematic liquid crystals, in three-dimensional
domains, subject to uniaxial boundary conditions. We analyze the physically relevant limit of small elastic constant and show
that global minimizers converge strongly, in W
1,2, to a global minimizer predicted by the Oseen–Frank theory for uniaxial nematic liquid crystals with constant order parameter.
Moreover, the convergence is uniform in the interior of the domain, away from the singularities of the limiting Oseen–Frank
global minimizer. We obtain results on the rate of convergence of the eigenvalues and the regularity of the eigenvectors of
the Landau–De Gennes global minimizer. We also study the interplay between biaxiality and uniaxiality in Landau–De Gennes
global energy minimizers and obtain estimates for various related quantities such as the biaxiality parameter and the size
of admissible strongly biaxial regions. 相似文献
13.
We consider a class of nonlinear Schrödinger equations in two space dimensions with an attractive potential. The nonlinearity is local but rather general encompassing for the first time both subcritical and supercritical (in L2) nonlinearities. We study the asymptotic stability of the nonlinear bound states, i.e. periodic in time localized in space solutions. Our result shows that all solutions with small initial data, converge to a nonlinear bound state. Therefore, the nonlinear bound states are asymptotically stable. The proof hinges on dispersive estimates that we obtain for the time-dependent, Hamiltonian, linearized dynamics around a carefully chosen one-parameter family of bound states that “shadows” the nonlinear evolution of the system. Due to the generality of the methods we develop we expect them to extend to the case of perturbations of large bound states and to other nonlinear dispersive wave type equations. 相似文献
14.
This article presents the vibration action on the human body found in a tram travel, where made the vibration measurements. Also presented a mathematical model with two degrees of freedom. Finally a comparison was made between the results obtained from measurements and the results of integration. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
Radu Ignat Luc Nguyen Valeriy Slastikov Arghir Zarnescu 《Comptes Rendus Mathematique》2018,356(9):922-926
For , we consider the Ginzburg–Landau functional for -valued maps defined in the unit ball with the vortex boundary data x on . In dimensions , we prove that, for every , there exists a unique global minimizer of this problem; moreover, is symmetric and of the form for . 相似文献
16.
The paper studies the motion laws influence over the VIPAS1 industrial robot working. The motion differential equations, that govern the motion robot were established. Using them we can study the direct problem for the robot dynamics. There are the given motion laws for the accelerated and decreasing motion having triangular, trapezoidal and parabolic forms. The graphics of the forces and moments give us the possibility to make some recommandations under energetic aspects, for the optimal solutions about the VIPAS1 industrial robot. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
Andreea Iosageanu Daniela Ilie Oana Craciunescu Ana-Maria Seciu-Grama Anca Oancea Otilia Zarnescu Ionut Moraru Florin Oancea 《Molecules (Basel, Switzerland)》2021,26(9)
In the present study, we evaluated for the first time the photoprotective effect of fish bone bioactive peptides (FBBP) preparation isolated from silver carp (Hypophthalmichthys molitrix) discarded tissue using in vitro experimental models of skin cells exposed to ultraviolet B (UVB) irradiation and stressing agents. FBBP preparation was obtained by papain treatment of minced bones and centrifugal ultrafiltration, and the molecular weight (MW) distribution was characterized by size exclusion and reversed-phase high performance liquid chromatography (RP-HPLC). In vitro assessment of the effect of FBBP pretreatment in UVB-irradiated L929 fibroblasts and HaCaT keratinocytes revealed their cytoprotective activity. Their capacity to efficiently reduce reactive oxygen species (ROS) production and lipid peroxidation varied in a dose-dependent manner, and it was greater in fibroblasts. A decrease of proinflammatory cytokines secretion, in particular of tumor necrosis factor alpha (TNF-α), was found after FBBP pretreatment of THP-1-derived inflamed macrophages. Melanin production and tyrosinase activity investigated in UVB-irradiated Mel-Juso cells were lowered in direct relation to FBBP concentrations. FBBP fractions with high radical scavenging activity were separated by ion exchange chromatography, and two collagenic sequences were identified. All these results offer new scientific data on aquaculture fish bone-derived peptides confirming their ability to control the antioxidant, anti-inflammatory and pigmentation processes developed during UV irradiation of skin cells and recommend their use as valuable natural ingredients of photoprotective cosmeceutical products. 相似文献
18.
The paper presents the study of the human body, as a mechanical system, seated inside an autovehicle and exposed under the vertical harmonic vibration action during the auto vehicle motion time. The human body may be roughly approximated by a linear lumped parameter at low frequencies and low vibration levels. Therefore, the model has 5 DOFs in translation, where 4 DOFs represents the human body and 1 DOF is for the seat cushion The mechanical model of the human body, in sitting position on the seat cushion of a vehicle seat, consists of four parts: pelvis, upper torso, viscera and head.. The eigenvalues for the human body – seat system and the damping ratio for the system was been calculate. The system stability analysis is given by the existence of a Lyapunov function for the system. The stability of a system can also be characterized by the eigenvalues of the system. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
The traffic of autovehicles in pilot zone of great city of Cluj-Napoca is presented in the work. There are established the noise measuring locations for the fixed station and successive positions of the mobile station in pilot zone. Noise pollution measurements are done on the mentioned locations. The “Sound plan” programme pack is used to fulfill the sound map of the great city of Cluj-Napoca; its graphic representation is compared to the real measurement results. Present paper represents a part of research activity of T.U.C.N. researchers in studying for fulfilling of E.U. tasks of environment protection. This research is made for the application of the EU legislation on the Romanian cities. First we worked in the great city of Cluj-Napoca, but the extensions will be to all the urban agglomerations having greater than 100000 people. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.