12,995 research outputs found
Magnetic properties of a novel Pr Fe Ti phase
In a systematic study of the (Pr1âxTix)Fe5 alloy series, the (Pr0.65Ti0.35)Fe5 alloy has been
found to have a dominant phase with either the rhombohedral Th2Zn17 structure or the
newly discovered Nd2(Fe,Ti)19 (S. J. Collocott, R. K. Day, J. B. Dunlop, and R. L. Davis,
in Proceedings of the Seventh International Symposium on Magnetic Anisotropy and
Coercivity in RâT Alloys, Canberra, July 1992, p. 437) structure, depending on the
annealing procedure. Powderâxârayâdiffraction patterns and scanning electron
microscopy show that the sample annealed at a temperature of 850â°C followed by
1000â°C has the 2:17 structure whereas annealing at 1000â°C directly leads to the new
2:19 structure. Energyâdispersive xâray analysis yields Pr:Fe:Ti ratios of 10.7:86.2:3.1
for the Pr2(Fe,Ti)17 phase and 9.2:85.9:4.9 for the Pr2(Fe,Ti)19 phase.
57
Fe Mössbauer
spectroscopy (at 295 K) gives values for the average
57
Fe hyperfine field of 15.7 T for the
2:17 phase and 17.5 T for the 2:19 phase, respectively
Fire responses and resistance of concrete-filled steel tubular frame structures
This paper presents the results of dynamic responses and fire resistance of concretefilled
steel tubular (CFST) frame structures in fire conditions by using non-linear finite element
method. Both strength and stability criteria are considered in the collapse analysis. The frame
structures are constructed with circular CFST columns and steel beams of I-sections. In order to
validate the finite element solutions, the numerical results are compared with those from a fire
resistance test on CFST columns. The finite element model is then adopted to simulate the
behaviour of frame structures in fire. The structural responses of the frames, including critical
temperature and fire-resisting limit time, are obtained for the ISO-834 standard fire. Parametric
studies are carried out to show their influence on the load capacity of the frame structures in fire.
Suggestions and recommendations are presented for possible adoption in future construction and
design of these structures
Accurate range-free localization for anisotropic wireless sensor networks
Journal ArticlePosition information plays a pivotal role in wireless sensor network (WSN) applications and protocol/ algorithm design. In recent years, range-free localization algorithms have drawn much research attention due to their low cost and applicability to large-scale WSNs. However, the application of range-free localization algorithms is restricted because of their dramatic accuracy degradation in practical anisotropic WSNs, which is mainly caused by large error of distance estimation. Distance estimation in the existing range-free algorithms usually relies on a unified per hop length (PHL) metric between nodes. But the PHL between different nodes might be greatly different in anisotropic WSNs, resulting in large error in distance estimation. We find that, although the PHL between different nodes might be greatly different, it exhibits significant locality; that is, nearby nodes share a similar PHL to anchors that know their positions in advance. Based on the locality of the PHL, a novel distance estimation approach is proposed in this article. Theoretical analyses show that the error of distance estimation in the proposed approach is only one-fourth of that in the state-of-the-art pattern-driven scheme (PDS). An anchor selection algorithm is also devised to further improve localization accuracy by mitigating the negative effects from the anchors that are poorly distributed in geometry. By combining the locality-based distance estimation and the anchor selection, a range-free localization algorithm named Selective Multilateration (SM) is proposed. Simulation results demonstrate that SM achieves localization accuracy higher than 0.3r, where r is the communication radius of nodes. Compared to the state-of-the-art solution, SM improves the distance estimation accuracy by up to 57% and improves localization accuracy by up to 52% consequently.This work is partially supported by the National Science Foundation of China (61103203, 61173169,
61332004, and 61420106009), the Hong Kong RGC General Research Fund (PolyU 5106/11E), the International Science & Technology Cooperation Program of China (2013DFB10070), and the EU FP7 QUICK project (PIRSES-GA-2013-612652)
Neutrino oscillations in Kerr-Newman space-time
The mass neutrino oscillation in Kerr-Newman(K-N) space-time is studied in
the plane , and the general equations of oscillation phases
are given. The effect of the rotation and electric charge on the phase is
presented. Then, we consider three special cases: (1) The neutrinos travel
along the geodesics with the angular momentum in the equatorial plane.
(2) The neutrinos travel along the geodesics with L=0 in the equatorial plane.
(3) The neutrinos travel along the radial geodesics at the direction
. At last, we calculate the proper oscillation length in the K-N
space time. The effect of the gravitational field on the oscillation length is
embodied in the gravitational red shift factor. When the neutrino travels out
of the gravitational field, the blue shift of the oscillation length takes
place. We discussed the variation of the oscillation length influenced by the
gravitational field strength, the rotation and charge .Comment: 20 pages, no figure
Relative entropy of entanglement of a kind of two qubit entangled states
We in this paper strictly prove that some block diagonalizable two qubit
entangled state with six none zero elements reaches its quantum relative
entropy entanglement by the a separable state having the same matrix structure.
The entangled state comprises local filtering result state as a special case.Comment: 5 page
Modified yupingfeng formula for the treatment of stable chronic obstructive pulmonary disease: a systematic review of randomized controlled trials
Background: Chronic obstructive pulmonary disease (COPD), is a very common disease of respiratory system. An increasing number of clinical trials on Yupingfeng formula in the management of stable COPD have been performed. However, the evidence base for it remains unknown. This review aims at assessing the efficacy, and safety of modified Yupingfeng formula in the treatment of stable COPD through a systematic review of all available randomized controlled trials. Materials and Methods: Literature retrieval was conducted using four English databases (CENTRAL, PubMed, EMBASE, and ISI Web of Science), and four Chinese databases (CBM, CNKI, VIP, and WANFANG), from respective inception to January 2013, and supplemented with a manual search. Review authors independently extracted the trial data, and assessed the quality of each trial. Methodological quality was assessed by Cochrane risk of bias and Jadadâs scale. The following outcomes were evaluated: (1) lung function; (2) 6-minute walk distance (6MWD); (3) effective rate; (4) serum levels of IgA, IgG and IgE; and (5) adverse events. Data were analyzed using STATA 12.0 software.Results: A total of nine studies involving 660, stable COPD patients were identified. Patients from all studies included in this review were randomized to receive Yupingfeng formula combined with Western medications in comparison with Western medications. In general, the methodological quality of the included trials was poor. The results of this systematic review indicates that, compared with Western medications alone, the use of Yupingfeng formula, if combined with Western medications could significantly improve FEV1 (WMD = 0.30L; 95%CI: 0.19, 0.42), FEV1/FVC ratio (SMD = 0.69; 95%CI: 0.48, 0.91), 6MWD (WMD = 31.73m; 95% CI: 19.29, 44.17), and effective rate (RR = 1.24; 95% CI: 1.10, 1.41), and increase the serum levels of IgA (WMD = 0.25; 95%CI: 0.16, 0.34) and IgG (WMD = 1.10; 95%CI: 0.53, 1.68), but no difference was found in the serum IgE levels (WMD = 0.47; 95%CI: ïŒ0.32, 1.27) between the two groups. No serious adverse events were reported.Conclusions: Within the limitations of this systematic review, we may conclude that compared with Western medications alone, Yupingfeng formula, when combined with Western medications can provide more benefits for patients with stable COPD, without any serious adverse reactions being identified. However, these benefits need to be further confirmed through high-quality prospective placebo-controlled trials that should be strictly conducted in accordance with methodological principles and procedures.Key words: Yupingfeng formula; chronic obstructive pulmonary disease; Systematic revie
Probing the Structure of Accreting Compact Sources Through X-Ray Time Lags and Spectra
We exhibit, by compiling all data sets we can acquire, that the Fourier
frequency dependent hard X-ray lags, first observed in the analysis of
aperiodic variability of the light curves of the black hole candidate Cygnus
X-1, appear to be a property shared by several other accreting black hole
candidate sources and also by the different spectral states of this source. We
then present both analytic and numerical models of these time lags resulting by
the process of Comptonization in a variety of hot electron configurations. We
argue that under the assumption that the observed spectra are due to
Comptonization, the dependence of the lags on the Fourier period provides a
means for mapping the spatial density profile of the hot electron plasma, while
the period at which the lags eventually level--off provides an estimate of the
size of the scattering cloud. We further examine the influence of the location
and spatial extent of the soft photon source on the form of the resulting lags
for a variety of configurations; we conclude that the study of the X-ray hard
lags can provide clues about these parameters of the Comptonization process
too. Fits of the existing data with our models indicate that the size of the
Comptonizing clouds are quite large in extent ( 1 light second) with
inferred radial density profiles which are in many instances inconsistent with
those of the standard dynamical models, while the extent of the source of soft
photons appears to be much smaller than those of the hot electrons by roughly
two orders of magnitude and its location consistent with the center of the hot
electron corona.Comment: 20 pages Latex, 11 postscript figures, to appear in the Astrophysical
Journal, Vol 512, Feb 20 issu
Energy-aware Dual-path Geographic Routing to Bypass Routing Holes in Wireless Sensor Networks
This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record.Geographic routing has been considered as an attractive approach for resource-constrained wireless sensor networks
(WSNs) since it exploits local location information instead of global topology information to route data. However, this routing approach
often suffers from the routing hole (i.e., an area free of nodes in the direction closer to destination) in various environments such as
buildings and obstacles during data delivery, resulting in route failure. Currently, existing geographic routing protocols tend to walk
along only one side of the routing holes to recover the route, thus achieving suboptimal network performance such as longer delivery
delay and lower delivery ratio. Furthermore, these protocols cannot guarantee that all packets are delivered in an energy-efficient
manner once encountering routing holes. In this paper, we focus on addressing these issues and propose an energy-aware dual-path
geographic routing (EDGR) protocol for better route recovery from routing holes. EDGR adaptively utilizes the location information,
residual energy, and the characteristics of energy consumption to make routing decisions, and dynamically exploits two node-disjoint
anchor lists, passing through two sides of the routing holes, to shift routing path for load balance. Moreover, we extend EDGR into
three-dimensional (3D) sensor networks to provide energy-aware routing for routing hole detour. Simulation results demonstrate that
EDGR exhibits higher energy efficiency, and has moderate performance improvements on network lifetime, packet delivery ratio, and
delivery delay, compared to other geographic routing protocols in WSNs over a variety of communication scenarios passing through
routing holes. The proposed EDGR is much applicable to resource-constrained WSNs with routing holes.This work has been partially supported by the National
Natural Science Foundation of China (No. 61402343,
No. 61672318, No. U1504614, No. 61631013, and No.
61303241), the National Key Research and Development
Program (No. 2016YFB1000102), the Natural Science
Foundation of Suzhou/Jiangsu Province (No.
BK20160385), the EU FP7 QUICK Project (No. PIRSESGA-
2013-612652), and the projects of Tsinghua National
Laboratory for Information Science and Technology
(TNList)
Spin and orbital angular momentum in gauge theories (II): QCD and nucleon spin structure
Parallel to the construction of gauge invariant spin and orbital angular
momentum for QED in paper (I) of this series, we present here an analogous but
non-trivial solution for QCD. Explicitly gauge invariant spin and orbital
angular momentum operators of quarks and gluons are obtained. This was
previously thought to be an impossible task, and opens a more promising avenue
towards the understanding of the nucleon spin structure.Comment: 3 pages, no figure; presented by F. Wang at NSTAR200
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