791 research outputs found
Optimal Uniform Pricing Strategy of a Service Firm When Facing Two Classes of Customers
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106838/1/poms12171.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106838/2/poms12171-sup-0001-Onlinesupplement.pd
Multipolar condensates and multipolar Josephson effects
When single-particle dynamics are suppressed in certain strongly correlated
systems, dipoles arise as elementary carriers of quantum kinetics. These
dipoles can further condense, providing physicists with a rich realm to study
fracton phases of matter. Whereas recent theoretical discoveries have shown
that an unconventional lattice model may host a dipole condensate as the ground
state, fundamental questions arise as to whether dipole condensation is a
generic phenomenon rather than a specific one unique to a particular model and
what new quantum macroscopic phenomena a dipole condensate may bring us with.
Here, we show that dipole condensates prevail in bosonic systems. Because of a
self-proximity effect, where single-particle kinetics inevitably induces a
finite order parameter of dipoles, dipole condensation readily occurs in
conventional normal phases of bosons. Our findings allow experimentalists to
manipulate the phase of a dipole condensate and deliver dipolar Josephson
effects, where supercurrents of dipoles arise in the absence of particle flows.
The self-proximity effects can also be utilized to produce a generic multipolar
condensate. The kinetics of the -th order multipoles unavoidably creates a
condensate of the -th order multipoles, forming a hierarchy of
multipolar condensates that will offer physicists a whole new class of
macroscopic quantum phenomena
Adaptive Control of Space Robot Manipulators with Task Space Base on Neural Network
As are considered, the body posture is controlled and position cannot control, space manipulator system model is difficult to be set up because of disturbance and model uncertainty. An adaptive control strategy based on neural network is put forward. Neural network on-line modeling technology is used to approximate the system uncertain model, and the strategy avoids solving the inverse Jacobi matrix, neural network approximation error and external bounded disturbance are eliminated by variable structure control controller. Inverse dynamic model of the control strategy does not need to be estimated, also do not need to take the training process, globally asymptotically stable of the closed-loop system is proved based on the lyapunov theory. The simulation results show that the designed controller can achieve high control precision has the important value of engineering application
Delivering universal health coverage for an aging population : an analysis of the Chinese rural health insurance program
There is now high level international commitment to the goal of universal health coverage. But how can countries make this a reality in the face of a limited budget and an aging population? Since 2008, China has been rolling out an ambitious reform program, which aims to achieve affordable health insurance coverage for all Chinese citizens. Under this reform program, Chinese living in rural areas are eligible to enroll in a subsidized scheme called the New Cooperative Medical System (NCMS). Using a three stage game model involving a government, a private fund manager and population, we explore the impact of population aging on NCMS. Our model highlights the role of government regulation and subsidy in ensuring operation efficiency of the system. We show that at optimality the government sets the operating framework for the fund manager to constrain the potential for monopoly profits. The Government subsidizes the scheme to prevent an adverse selection death spiral. However, the effectiveness of the subsidy in achieving this goal is moderated by the age structure of the population. Our model gives insights into the strengths of the NCMS framework and also can be used to support decisions about resource allocation and understand how scheme dynamics may unfold as the Chinese population ages further
Spontaneous edge-defect formation and defect-induced conductance suppression in graphene nanoribbons
We present a first-principles study of the migration and recombination of
edge defects (carbon adatom and/or vacancy) and their influence on electrical
conductance in zigzag graphene nanoribbons (ZGNRs). It is found that at room
temperature, the adatom is quite mobile while the vacancy is almost immobile
along the edge of ZGNRs. The recombination of an adatom-vacancy pair leads to a
pentagon-heptagon ring defect structure having a lower energy than the perfect
edge, implying that such an edge-defect can be formed spontaneously. This edge
defect can suppresses the conductance of ZGNRs drastically, which provides some
useful hints for understanding the observed semiconducting behavior of the
fabricated narrow GNRs.Comment: 6 pages, 4 figures, to appear in PR
Non-gapless excitation and zero-bias fast oscillations in the LDOS of surface superconducting states
Recently a novel surface pair-density-wave (PDW) superconducting state has
been discovered in Refs. [Phys. Rev. Lett. \textbf{122}, 165302 (2019)] and
Phys. Rev. B \textbf{101}, 054506 (2020)], which may go through a distinct
multiple phase transition (MPT) when the superconductivity fades away from bulk
to the boundary (e.g. edges and corners). Based on the Bogoliubov-de Gennes
equations for the attractive tight-binding Hubbard modal in a one-dimensional
chain, we demonstrate that the surface PDW state has a non-gapless
quasiparticle spectrum, which is contrary to the conventional surface
superconducting state. Moreover, we find that the MPT is associated with a
zero-bias fast oscillating pattern in the LDOS near the surface. Our findings
provide a potential experimental clue to identify the surface PDW state.Comment: 4 figure
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