11,641 research outputs found
A finite element method of the self-consistent field theory on general curved surfaces
Block copolymers provide a wonderful platform in studying the soft condensed
matter systems. Many fascinating ordered structures have been discovered in
bulk and confined systems. Among various theories, the self-consistent field
theory (SCFT) has been proven to be a powerful tool for studying the
equilibrium ordered structures. Many numerical methods have been developed to
solve the SCFT model. However, most of these focus on the bulk systems, and
little work on the confined systems, especially on general curved surfaces. In
this work, we developed a linear surface finite element method, which has a
rigorous mathematical theory to guarantee numerical precsion, to study the
self-assembled phases of block copolymers on general curved surfaces based on
the SCFT. Furthermore, to capture the consistent surface for a given
self-assembled pattern, an adaptive approach to optimize the size of the
general curved surface has been proposed. To demonstrate the power of this
approach, we investigate the self-assembled patterns of diblock copolymers on
several distinct curved surfaces, including five closed surfaces and an
unclosed surface. Numerical results illustrate the efficiency of the proposed
method. The obtained ordered structures are consistent with the previous
results on standard surfaces, such as sphere and torus. Certainly, the proposed
numerical framework has the capability of studying the phase behaviors on
general surfaces precisely
Decoherence and Energy Relaxation in the Quantum-Classical Dynamics for Charge Transport in Organic Semiconducting Crystals: an Instantaneous Decoherence Correction Approach
We explore an instantaneous decoherence correction (IDC) approach for the
decoherence and energy relaxation in the quantum-classical dynamics of charge
transport in organic semiconducting crystals. These effects, originating from
environmental fluctuations, are essential ingredients of the carrier dynamics.
The IDC is carried out by measurement-like operations in the adiabatic
representation. While decoherence is inherent in the IDC, energy relaxation is
taken into account by considering the detailed balance through the introduction
of energy-dependent reweighing factors, which could be either Boltzmann
(IDC-BM) or Miller-Abrahams (IDC-MA) type. For a non-diagonal electron-phonon
coupling model, it is shown that the IDC tends to enhance diffusion while
energy relaxation weakens this enhancement. As expected, both the IDC-BM and
IDC-MA achieve a near-equilibrium distribution at finite temperatures in the
diffusion process, while the Ehrenfest dynamics renders system tending to
infinite temperature limit. The resulting energy relaxation times with the two
kinds of factors lie in different regimes and exhibit different dependence on
temperature, decoherence time and electron-phonon coupling strength, due to
different dominant relaxation process.Comment: 8 pages, 4 figure
A New Kind of Deformed Hermite Polynomials and Its Applications
A new kind of deformed calculus was introduced recently in studying of
parabosonic coordinate representation. Based on this deformed calculus, a new
deformation of Hermite polynomials is proposed, its some properties such as
generating function, orthonormality, differential and integral representaions,
and recursion relations are also discussed in this paper. As its applications,
we calculate explicit forms of parabose squeezed number states, derive a
particularly simple subset of minimum uncertainty states for parabose
amplitude-squared squeezing, and discuss their basic squeezing behaviours.Comment: 18 pages, LaTe
Graded Lie Algebra Generating of Parastatistical Algebraic Structure
A new kind of graded Lie algebra (we call it graded Lie algebra) is
introduced as a framework for formulating parasupersymmetric theories. By
choosing suitable bose subspace of the graded Lie algebra and using
relevant generalized Jacobi identities, we generate the whole algebraic
structure of parastatistics.Comment: 8 pages, LaTe
Space Structure for the Simplest Parasupersymmetric System
Structure of the state-vector space for a system consisting of one mode
parabose and one mode parafermi degree of freedom with the same parastatistics
order is studied and a complete, orthonormal set of basis vectors in this
space is constructed. There is an intrinsic double degeneracy for state vectors
with parabosons and parafermions, where , , and
. It is also shown that the degeneracy plays a key role in
realization of exact supersymmetry for such a system
Hybrid-BCP: A Robust Load Balancing and Routing Protocol for Intra-Car Wired/Wireless Networks
With the emergence of connected and autonomous vehicles, sensors are
increasingly deployed within cars to support new functionalities. Traffic
generated by these sensors congest traditional intra-car networks, such as CAN
buses. Furthermore, the large amount of wires needed to connect sensors makes
it harder to design cars in a modular way. To alleviate these limitations, we
propose, simulate, and implement a hybrid wired/wireless architecture, in which
each node is connected to either a wired interface or a wireless interface or
both. Specifically, we propose a new protocol, called Hybrid-Backpressure
Collection Protocol (Hybrid-BCP), to efficiently collect data from sensors in
intra-car networks. Hybrid-BCP is backward-compatible with the CAN bus
technology, and builds on the BCP protocol, designed for wireless sensor
networks. Hybrid-BCP achieves high throughput and shows resilience to dynamic
network conditions, including adversarial interferences. Our testbed
implementation, based on CAN and ZigBee transceivers, demonstrates the load
balancing and routing functionalities of Hybrid-BCP and its resilience to DoS
attacks. We further provide simulation results, obtained with the ns-3
simulator and based on real intra-car RSSI traces, that compare between the
performance of Hybrid-BCP and a tree-based collection protocol. Notably, the
simulations show that Hybrid-BCP can achieve the same performance as the
tree-based protocol while reducing the radio transmission power by a factor of
10
Vorticity, Gyroscopic precession, and Spin-Curvature Force
In investigating the relation between vorticity and gyroscopic precession, we
calculate the vorticity vector in Godel, Kerr, Lewis, Schwarzschild, Minkowski
metric and find out the vorticity vector of the specific observers is the
angular velocity of gyroscopic precession. Furthermore, considering space-time
torsion will flip the vorticity and spin-curvature force to opposite sign. This
result is very similar to the behavior of positive and negative helicity of
quantum spin in Stern-Gerlach force. It implies that the inclusion of torsion
will lead to analogous property of quantum spin even in classical treatment
A New Parameter Estimation Algorithm Based on Sub-band Dual Frequency Conjugate LVT
A new parameter estimation algorithm, known as Sub-band Dual Frequency
Conjugate LVT (SDFC-LVT), is proposed for the ground moving targets. This
algorithm first constructs two sub-band signals with different central
frequencies. After that, the two signals are shifted by different values in
frequency domain and a new signal is constructed by multiplying one with the
conjugate of the other. Finally, Keystone transform and LVT operation are
performed on the constructed signal to attain the estimates. The cross-term and
the performance of the proposed method are analyzed in detail. Since the
equivalent carrier frequency is reduced greatly, the proposed method is capable
of obtaining the accurate parameter estimates and resolving the problem of
ambiguity which invalidates Keystone transform. It is search-free and can
compensate the range walk of multiple targets simultaneously, thereby reducing
the computational burden. The effectiveness of the proposed method is
demonstrated by both simulated and real data.Comment: 27 pages, 7 figure
Drift of Charge Carriers in Crystalline Organic Semiconductors
We investigate the direct-current response of crystalline organic
semiconductors in the presence of finite external electric fields by the
quantum-classical Ehrenfest dynamics complemented with instantaneous
decoherence corrections (IDC). The IDC is carried out in the real-space
representation with the energy-dependent reweighing factors to account for both
intermolecular decoherence and energy relaxation by which conduction occurs. In
this way, both the diffusion and drift motion of charge carriers are described
in a unified framework. Based on an off-diagonal electron-phonon coupling model
for pentacene, we find that the drift velocity initially increases with the
electric field and then decreases at higher fields due to the Wannier-Stark
localization, and a negative electric-field dependence of mobility is observed.
The Einstein relation, which is a manifestation of the fluctuation-dissipation
theorem, is found to be restored in electric fields up to ~ V/cm for a
wide temperature region studied. Furthermore, we show that the incorporated
decoherence and energy relaxation could explain the large discrepancy between
the mobilities calculated by the Ehrenfest dynamics and the full quantum
methods, which proves the effectiveness of our approach to take back these
missing processes.Comment: 8 pages, 5 figure
Parameter Estimation of Ground Moving Targets Based on SKT-DLVT Processing
It is well known that the motion of a ground moving target may induce the
range cell migration, spectrum spread and velocity ambiguity during the imaging
time, which makes the image smeared. To eliminate the influence of these
factors on image focusing, a novel method for parameter estimation of ground
moving targets, known as SKT-DLVT, is proposed in this paper. In this method,
the segmental keystone transform (SKT) is used to correct the range walk of
targets simultaneously, and a new transform, namely, Doppler Lv's transform
(LVT) is applied on the azimuth signal to estimate the parameters. Theoretical
analysis confirms that no interpolation is needed for the proposed method and
the targets can be well focused within limited searching range of the ambiguity
number. The proposed method is capable of obtaining the accurate parameter
estimates efficiently in the low signal-to-noise ratio (SNR) scenario with low
computational burden and memory cost, making it suitable to be applied in
memory-limited and real-time processing systems. The effectiveness of the
proposed method is demonstrated by both simulated and real data.Comment: 39 pages, 9 figure
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