748 research outputs found
Hybrid fundamental solution based finite element method: theory and applications
An overview on the development of hybrid fundamental solution based finite element method (HFS-FEM) and its application in engineering problems is presented in this paper. The framework and formulations of HFS-FEM for potential problem, plane elasticity, three-dimensional elasticity, thermoelasticity, anisotropic elasticity, and plane piezoelectricity are presented. In this method, two independent assumed fields (intraelement filed and auxiliary frame field) are employed. The formulations for all cases are derived from the modified variational functionals and the fundamental solutions to a given problem. Generation of elemental stiffness equations from the modified variational principle is also described. Typical numerical examples are given to demonstrate the validity and performance of the HFS-FEM. Finally, a brief summary of the approach is provided and future trends in this field are identified
Searching for Charged Higgs Boson in Polarized Top Quark
The charged Higgs boson is quite common in many new physics models. In this
study we examine the potential of observing a heavy charged Higgs boson in its
decay mode of top-quark and bottom-quark in the Type-II
Two-Higgs-Doublet-Model. In this model, the chirality structure of the coupling
of charged Higgs boson to the top- and bottom-quark is very sensitive to the
value of . As the polarization of the top-quark can be measured
experimentally from the top-quark decay products, one could make use of the
top-quark polarization to determine the value of . We preform a
detailed analysis of measuring top-quark polarization in the production
channels and . We calculate the helicity
amplitudes of the charged Higgs boson production and decay.Our calculation
shows that the top-quark from the charged Higgs boson decay provides a good
probe for measuring , especially for the intermediate
region. On the contrary, the top-quark produced in association with the charged
Higgs boson cannot be used to measure because its polarization is
highly contaminated by the -channel kinematics.Comment: 21 pages, 12 figures, 2 table
Layout optimization for multi-bi-modulus materials system under multiple load cases
Financial support from the National Natural Science
Foundation of China (Grant No. 51179164) and the Australian Research Council (Grant No. DP140103137) is acknowledged
Signature of Pseudo Nambu-Goldstone Higgs boson in its Decay
If the Higgs boson is a pseudo Nambu-Goldstone boson (PNGB), the
contact interaction induced by the invariants of the
non-linear sigma model is free from its nonlinearity effects. The process
can be used to eliminate the universal effects of heavy
particles, which can fake the nonlinearity effects of the PNGB Higgs boson in
the process (,\ ). We demonstrate that the
ratio of the signal strength of and
is good to distinguish the signature of the PNGB Higgs boson from Higgs
coupling deviations
Hybrid graded element model for nonlinear functionally graded materials
A hybrid graded element model is developed in this article for solving the heat conduction problem of nonlinear functionally graded materials (FGMs), whose material properties not only vary spatially but also are temperature dependent. In the proposed approach, both Kirchhoff transformation and iterative method are introduced to deal with the nonlinear term in the heat conduction equation of nonlinear FGMs. Then, the graded element is formulated based on two sets of independent temperature fields. One is the intra-element temperature field, which is defined within the element domain and constructed by a linear combination of fundamental solutions; the other is the frame field, which is defined on the element boundary only and used as the boundary interpolation functions of the element to ensure the field continuity over the inter-element boundary. This model can simulate the graded material properties naturally due to the inherent properties of fundamental solutions, which are employed in constructing the graded element. Moreover, a multi-subdomain method is developed to deal with the problem with different materials. Finally, the performance of the proposed method is assessed by several benchmark examples. The results are in excellent agreement with the analytical solutions
Spin susceptibility of Anderson impurities in arbitrary conduction bands
Spin susceptibility of Anderson impurities is a key quantity in understanding
the physics of Kondo screening. Traditional numerical renormalization group
(NRG) calculation of the impurity contribution to
susceptibility, defined originally by Wilson in a flat wide band, has been
generalized before to structured conduction bands. The results brought about
non-Fermi-liquid and diamagnetic Kondo behaviors in , even
when the bands are not gapped at the Fermi energy. Here, we use the full
density-matrix (FDM) NRG to present high-quality data for the local
susceptibility and to compare them with
obtained by the traditional NRG. Our results indicate
that those exotic behaviors observed in are unphysical.
Instead, the low-energy excitations of the impurity in arbitrary bands only
without gap at the Fermi energy are still a Fermi liquid and paramagnetic. We
also demonstrate that unlike the traditional NRG yielding
less accurate than , the FDM method allows a
high-precision dynamical calculation of at much reduced
computational cost, with an accuracy at least one order higher than
. Moreover, artifacts in the FDM algorithm to
, and origins of the spurious non-Fermi-liquid and
diamagnetic features are clarified. Our work provides an efficient
high-precision algorithm to calculate the spin susceptibility of impurity for
arbitrary structured bands, while negating the applicability of Wilson's
definition to such cases.Comment: the published versio
Recent advances in electronic skins: material progress and applications
Electronic skins are currently in huge demand for health monitoring platforms and personalized medicine applications. To ensure safe monitoring for long-term periods, high-performance electronic skins that are softly interfaced with biological tissues are required. Stretchability, self-healing behavior, and biocompatibility of the materials will ensure the future application of electronic skins in biomedical engineering. This mini-review highlights recent advances in mechanically active materials and structural designs for electronic skins, which have been used successfully in these contexts. Firstly, the structural and biomechanical characteristics of biological skins are described and compared with those of artificial electronic skins. Thereafter, a wide variety of processing techniques for stretchable materials are reviewed, including geometric engineering and acquiring intrinsic stretchability. Then, different types of self-healing materials and their applications in electronic skins are critically assessed and compared. Finally, the mini-review is concluded with a discussion on remaining challenges and future opportunities for materials and biomedical research
Effect of Tumor Necrosis Factor-α on Neutralization of Ventricular Fibrillation in Rats with Acute Myocardial Infarction
The purpose of this study was to explore the effects of tumor necrosis factor-α (TNF-α) on ventricular fibrillation (VF) in rats with acute myocardial infarction (AMI). Rats were randomly classified into AMI group, sham operation group and recombinant human tumor necrosis factor receptor:Fc fusion protein (rhTNFR:Fc) group. Spontaneous and induced VFs were recorded. Monophasic action potentials (MAPs) among different zones of myocardium were recorded at eight time points before and after ligation and MAP duration dispersions (MAPDds) were calculated. Then expression of TNF-α among different myocardial zones was detected. After ligation of the left anterior descending coronary artery, total TNF-α expression in AMI group began to markedly increase at 10âmin, reached a climax at 20â30min, and then gradually decreased. The time-windows of VFs and MAPDds in the border zone performed in a similar way. At the same time-point, the expression of TNF-α in the ischemia zone was greater than that in the border zone, and little in the non-ischemia zone. Although the time windows of TNF-α expression, the MAPDds in the border zone and the occurrence of VFs in the rhTNFR:Fc group were similar to those in the AMI group, they all decreased in the rhTNFR:Fc group. Our findings demonstrate that TNF-α could enlarge the MAPDds in the border zone, and promote the onset of VFs
Safety and efficacy of etomidate and propofol anesthesia in elderly patients undergoing gastroscopy: A double-blind randomized clinical study
The aim of the present study is to compare the safety, efficacy and cost effectiveness of anesthetic regimens by compound, using etomidate and propofol in elderly patients undergoing gastroscopy. A total of 200 volunteers (65â79 years of age) scheduled for gastroscopy under anesthesia were randomly divided into the following groups: P, propofol (1.5â2.0 mg/kg); E, etomidate (0.15-0.2 mg/kg); P+E, propofol (0.75â1 mg/kg) followed by etomidate (0.075-0.1 mg/kg); and E+P, etomidate (0.075-0.01 mg/kg) followed by propofol (0.75â1 mg/kg). Vital signs and bispectral index were monitored at different time points. Complications, induction and examination time, anesthesia duration, and recovery and discharge time were recorded. At the end of the procedure, the satisfaction of patients, endoscopists and the anesthetist were evaluated. The recovery (6.1±1.2 h) and discharge times (24.8±2.8 h) in group E were significantly longer compared with groups P, P+E and E+P (P<0.05). The occurrence of injection pain in group P+E was significantly higher compared with the other three groups (P<0.05). In addition, the incidence of myoclonus and post-operative nausea and vomiting were significantly higher in group P+E compared with the other three groups (P<0.05). There was no statistical difference among the four groups with regards to the patients' immediate, post-procedure satisfaction (P>0.05). Furthermore, there was no difference in the satisfaction of anesthesia, as evaluated by the anesthetist and endoscopist, among the four groups (P>0.05). The present study demonstrates that anesthesia for gastroscopy in elderly patients can be safely and effectively accomplished using a drug regimen that combines propofol with etomidate. The combined use of propofol and etomidate has unique characteristics which improve hemodynamic stability, cause minimal respiratory depression and less side effects, provide rapid return to full activity and result in high levels of satisfaction
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