Abstract: The near-field synthetic aperture radar (SAR) imaging
is an advanced nondestructive testing and evaluation (NDT&E)
technique. This paper investigates the complex-valued signal
processing related to the near-field SAR imaging system, where
the measurement data turns out to be noncircular and improper,
meaning that the complex-valued data is correlated to its complex
conjugate. Furthermore, we discover that the degree of impropriety
of the measurement data and that of the target image can be highly
correlated in near-field SAR imaging. Based on these observations, A
modified generalized sparse Bayesian learning algorithm is proposed,
taking impropriety and noncircularity into account. Numerical results
show that the proposed algorithm provides performance gain, with the
help of noncircular assumption on the signals.
Abstract: In this paper, by constructing a special set and utilizing
fixed point theory, we study the existence and multiplicity of the
positive solutions for systems of nonlinear third-order differential
equations with p-laplacian, which improve and generalize the result
of related paper.
Abstract: With the rapid development of national modern industry, people begin to pay attention to environmental pollution and harm caused by industrial dust. Based on above, a numerical study on the dedusting technology of industrial environment was conducted. The dynamic models of multicomponent particles collision and coagulation, breakage and deposition are developed, and the interaction of water droplet and aerosol particle in 2-Dimension flow field was researched by Eulerian-Lagrangian method and Multi-Monte Carlo method. The effects of the droplet scale, movement speed of droplet and the flow field structure on scavenging efficiency were analyzed. The results show that under the certain condition, 30μm of droplet has the best scavenging efficiency. At the initial speed 1m/s of droplets, droplets and aerosol particles have more time to interact, so it has a better scavenging efficiency for the particle.
Abstract: In this paper, by constructing a special operator and using fixed point index theorem of cone, we get the sufficient conditions for symmetric positive solution of a class of nonlinear singular boundary value problems with p-Laplace operator, which improved and generalized the result of related paper.
Abstract: In this paper, by constructing a special set and utilizing fixed point index theory, we study the existence of solution for singular differential equation in Banach space, which improved and generalize the result of related paper.
Abstract: In this paper, by constructing a special non-empty closed convex set and utilizing M¨onch fixed point theory, we investigate the existence of solution for a class of fourth-order singular differential equation in Banach space, which improved and generalized the result of related paper.
Abstract: In this paper, by constructing a special operator and using fixed point index theorem of cone, we get the sufficient conditions for symmetric positive solution of a class of nonlinear singular boundary value problems with p-Laplace operator, which improved and generalized the result of related paper.
Abstract: How to simulate experimentally the air flow and heat
transfer under microgravity on the ground is important, which has not
been completely solved so far. Influence of gravity on air natural
convection results in convection heat transfer on ground difference
from that on orbit. In order to obtain air temperature and velocity
deviations of manned spacecraft during terrestrial thermal test,
dimensionless number analysis and numerical simulation analysis are
performed. The calculated temperature distribution and velocity
distribution of the horizontal test cases are compared to the vertical
cases. The results show that the influence of gravity is neglected for
facility drawer racks and more obvious for vertical cabins.
Abstract: In this paper, by constructing a special set and utilizing fixed point index theory, we study the existence of solution for the boundary value problem of second-order singular differential equations in Banach space, which improved and generalize the result of related paper.
Abstract: This paper analysis the integrated use of safety monitoring with the domestic and international latest research on rail safety protection system, and focus on the implementation of an organic whole system, with the monitoring and early warning, risk assessment, predictive control and emergency rescue system. The system framework, contents and system structure of Security system is proposed completely. It-s pointed out that the Security system is a negative feedback system composed of by safety monitoring and warning system, risk assessment and emergency rescue system. Safety monitoring and warning system focus on the monitoring target monitoring, early warning, tracking, integration of decision-making, for objective and subjective risks factors. Risk assessment system analysis the occurrence of a major Security risk mechanism, determines the standard of the future short, medium and long term safety conditions, and give prop for development of safety indicators, accident analysis and safety standards. Emergency rescue system is with the goal of rapid and effective rescue work for accident, to minimize casualties and property losses.
Abstract: In the paper, the performance of quasi-synchronous
CDMA (QS-CDMA) system, which can allow an increased timing
error in synchronized access, is discussed. Average BER performance
of the system is analyzed in the condition of different access timing
error and different asynchronous users by simulation in AWGN
channel. The results show that QS-CDMA system is shown to have
great performance gain over the asynchronous system when access
timing error is within a few chips and asynchronous users is tolerable.
However, with access timing error increasing and asynchronous users
increasing, the performance of QS-CDMA will degrade. Also, we can
determine the number of tolerable asynchronous users for different
access timing error by simulation figures.
Abstract: Multicarrier code-division multiple-access is one of the
effective techniques to gain its multiple access capability, robustness
against fading, and to mitigate the ISI. In this paper, we propose an
improved mulcarrier CDMA system with adaptive subchannel
allocation. We analyzed the performance of our proposed system in
frequency selective fading environment with narrowband interference
existing and compared it with that of parallel transmission over many
subchannels (namely, conventional MC-CDMA scheme) and
DS-CDMA system. Simulation results show that adaptive subchannel
allocation scheme, when used in conventional multicarrier CDMA
system, the performance will be greatly improved.
Abstract: In order to make environmental test centrifuge balance
automatically and accurately, reduce unbalance centrifugal force,
balance adjusting system of centrifuge is designed. The new balance
adjusting system comprises motor-reducer, timing belt, screw pair,
slider-guideway and four rocker force sensors. According to
information obtained by the four rocker force sensors, unbalanced
value at both ends of the big arm is computed and heavy block is
moved to achieve balance adjusting. In this paper, motor power and
torque to move the heavy block is calculated. In full load running
progress of centrifuge, the stress-strain of screw pair composed by
adjusting nut and big arm are analyzed. A successful application of the
balance adjusting system is also put forwarded. The results show that
the balance adjusting system can satisfy balance require of
environmental test centrifuge.