826 research outputs found
Elasticity solutions for a transversely isotropic functionally graded circular plate subject to an axisymmetric transverse load qrk
AbstractThis paper considers the bending of transversely isotropic circular plates with elastic compliance coefficients being arbitrary functions of the thickness coordinate, subject to a transverse load in the form of qrk (k is zero or a finite even number). The differential equations satisfied by stress functions for the particular problem are derived. An elaborate analysis procedure is then presented to derive these stress functions, from which the analytical expressions for the axial force, bending moment and displacements are obtained through integration. The method is then applied to the problem of transversely isotropic functionally graded circular plate subject to a uniform load, illustrating the procedure to determine the integral constants from the boundary conditions. Analytical elasticity solutions are presented for simply-supported and clamped plates, and, when degenerated, they coincide with the available solutions for an isotropic homogenous plate. Two numerical examples are finally presented to show the effect of material inhomogeneity on the elastic field in FGM plates
E-Waste Recycling and Related Social Issues in China
AbstractChina has set a goal of establishing a Circular Economy policy for recycling resources in the near future. To further efforts to build a circular society, we analyzed the current status of E-waste recycling and related social issues, including the case of Guiyu town. Some policy suggestions on establishing recycling systems are recommended
Impacts of environmental factors and human disturbance on composition of roadside vegetation in Xishuangbanna National Nature Reserve of Southwest China
AbstractVegetation-disturbance-environment relationships in Xishuangbanna Nature Reserve (XNR) was examined using multivariate analysis to understand the impacts of environmental factors and human disturbance on vegetation along the highway corridor. The results show that native forests were the best habitat for protected/endangered species and native species. The exotic plants Eupatorium odoratum and Eupatorium adenophora were found primarily in secondary forests and their presence was positively associated with altitude and soil potassium concentrations. The distribution of two protected plants, Phoebe nanmu and Pometia tomentosa, was negatively associated with road disturbance. Understanding the complex effects of environmental factors and human disturbance is key for developing conservation and restoration strategies for roadside plant ecosystems
An Exact Diagonalization Demonstration of Incommensurability and Rigid Band Filling for N Holes in the t-J Model
We have calculated S(q) and the single particle distribution function
for N holes in the t - J model on a non--square sqrt{8} X sqrt{32} 16--site
lattice with periodic boundary conditions; we justify the use of this lattice
in compariosn to those of having the full square symmetry of the bulk. This new
cluster has a high density of vec k points along the diagonal of reciprocal
space, viz. along k = (k,k). The results clearly demonstrate that when the
single hole problem has a ground state with a system momentum of vec k =
(pi/2,pi/2), the resulting ground state for N holes involves a shift of the
peak of the system's structure factor away from the antiferromagnetic state.
This shift effectively increases continuously with N. When the single hole
problem has a ground state with a momentum that is not equal to k =
(pi/2,pi/2), then the above--mentioned incommensurability for N holes is not
found. The results for the incommensurate ground states can be understood in
terms of rigid--band filling: the effective occupation of the single hole k =
(pi/2,pi/2) states is demonstrated by the evaluation of the single particle
momentum distribution function . Unlike many previous studies, we show
that for the many hole ground state the occupied momentum states are indeed k =
(+/- pi/2,+/- pi/2) states.Comment: Revtex 3.0; 23 pages, 1 table, and 13 figures, all include
Quasiparticle scattering and local density of states in the d-density wave phase
We study the effects of single-impurity scattering on the local density of
states in the high- cuprates. We compare the quasiparticle interference
patterns in three different ordered states: d-wave superconductor (DSC),
d-density wave (DDW), and coexisting DSC and DDW (DSC-DDW). In the coexisting
state, at energies below the DSC gap, the patterns are almost identical to
those in the pure DSC state with the same DSC gap. However, they are
significantly different for energies greater than or equal to the DSC gap. This
transition at an energy around the DSC gap can be used to test the nature of
the superconducting state of the underdoped cuprates by scanning tunneling
microscopy. Furthermore, we note that in the DDW state the effect of the
coherence factors is stronger than in the DSC state. The new features arising
due to DDW ordering are discussed.Comment: 6 page, 5 figures (Higher resolution figures are available by
request
Blow up criterion for compressible nematic liquid crystal flows in dimension three
In this paper, we consider the short time strong solution to a simplified
hydrodynamic flow modeling the compressible, nematic liquid crystal materials
in dimension three. We establish a criterion for possible breakdown of such
solutions at finite time in terms of the temporal integral of both the maximum
norm of the deformation tensor of velocity gradient and the square of maximum
norm of gradient of liquid crystal director field.Comment: 22 page
Guided internet-based cognitive-behavioral therapy for patients with rheumatic conditions: a systematic review
Context: Rheumatic conditions have a large impact on both patients and society. Many patients experience adjustment problems, such as symptoms of anxiety and depression and sleep problems, contributing to high healthcare costs. Internet-based cognitive-behavioral therapy (iCBT) has shown to support patients with somatic conditions in coping with their disease, with therapist-guided iCBT usually showing larger effects than unguided iCBT. However, the specific relevance of guided iCBT for rheumatic conditions has not been reviewed yet, which could have important implications for implementation. Objectives: The objective of our review was to give an overview of evaluations of guided iCBT for rheumatic conditions, including physical, psychological, and impact on daily life outcomes. Methods: This review is registered with PROSPERO with registration number CRD42020154911. The review followed PRISMA guidelines and included an assessment of risk of bias. PubMed, PsycINFO, Embase, Cochrane Library, Web of Science, and Emcare were searched until 5 October 2020. Inclusion criteria were: patients >= 18 years old with a rheumatic condition, randomized controlled trial, accessible full-text English article, original data, inclusion of psychological, and/or physical and/or impact outcomes, and therapist-guided iCBT. Study and sample characteristics, as well as clinical variables were extracted. Results: A systematic search identified 6089 studies, of which 8 trials were included, comprising of 1707 participants in total. Significant medium to large between-group effects were found for psychological outcomes (depression, anxiety, catastrophizing, self-efficacy) and impact on daily life outcomes (impact on daily life, quality of life), whilst results for physical outcomes (pain intensity, fatigue) were mixed. Conclusion: Whilst more research is warranted, for instance regarding physical outcomes, cost-effectiveness, safety of the intervention, and moderators of iCBT success, our results show that guided iCBT could be an important addition to medical treatment for rheumatic conditions. Guided iCBT can improve psychological and impact on daily life outcomes in patients with rheumatic conditions, which is promising for iCBT implementation in clinical practice.Clinical epidemiolog
Role of Inter-Electron Interaction in the Pseudo-Gap Opening in High T Tunneling Experiments
The analysis of tunneling experiments showing the pseudogap type behavior is
carried out based on the idea of the renormalization of density of states due
to the inter-electron interaction in the Cooper channel (superconducting
fluctuations contribution in tunneling current). It is demonstrated that the
observed kink of the zero-bias conductance of junctions in
the vicinity of can be explained in terms of fluctuation theory in a
quite wide range of temperature above , using the values of microscopic
parameters of the electron spectrum taken from independent
experiments. The approach proposed also permits to explain qualitatively the
shape of the tunneling anomalies in and gives a correct estimate for
the pseudogap position and amplitude observed in the experiments on
junctions.Comment: 5 pages, 3 figure
Pinned Balseiro-Falicov Model of Tunneling and Photoemission in the Cuprates
The smooth evolution of the tunneling gap of Bi_2Sr_2CaCu_2O_8 with doping
from a pseudogap state in the underdoped cuprates to a superconducting state at
optimal and overdoping, has been interpreted as evidence that the pseudogap
must be due to precursor pairing. We suggest an alternative explanation, that
the smoothness reflects a hidden SO(N) symmetry near the (pi,0) points of the
Brillouin zone (with N = 3, 4, 5, or 6). Because of this symmetry, the
pseudogap could actually be due to any of a number of nesting instabilities,
including charge or spin density waves or more exotic phases. We present a
detailed analysis of this competition for one particular model: the pinned
Balseiro-Falicov model of competing charge density wave and (s-wave)
superconductivity. We show that most of the anomalous features of both
tunneling and photoemission follow naturally from the model, including the
smooth crossover, the general shape of the pseudogap phase diagram, the
shrinking Fermi surface of the pseudogap phase, and the asymmetry of the
tunneling gap away from optimal doping. Below T_c, the sharp peak at Delta_1
and the dip seen in the tunneling and photoemission near 2Delta_1 cannot be
described in detail by this model, but we suggest a simple generalization to
account for inhomogeneity, which does provide an adequate description. We show
that it should be possible, with a combination of photoemission and tunneling,
to demonstrate the extent of pinning of the Fermi level to the Van Hove
singularity. A preliminary analysis of the data suggests pinning in the
underdoped, but not in the overdoped regime.Comment: 18 pages LaTeX, 26 ps. figure
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