9,343 research outputs found
Distributed Stochastic Optimization over Time-Varying Noisy Network
This paper is concerned with distributed stochastic multi-agent optimization
problem over a class of time-varying network with slowly decreasing
communication noise effects. This paper considers the problem in composite
optimization setting which is more general in noisy network optimization. It is
noteworthy that existing methods for noisy network optimization are Euclidean
projection based. We present two related different classes of non-Euclidean
methods and investigate their convergence behavior. One is distributed
stochastic composite mirror descent type method (DSCMD-N) which provides a more
general algorithm framework than former works in this literature. As a
counterpart, we also consider a composite dual averaging type method (DSCDA-N)
for noisy network optimization. Some main error bounds for DSCMD-N and DSCDA-N
are obtained. The trade-off among stepsizes, noise decreasing rates,
convergence rates of algorithm is analyzed in detail. To the best of our
knowledge, this is the first work to analyze and derive convergence rates of
optimization algorithm in noisy network optimization. We show that an optimal
rate of in nonsmooth convex optimization can be obtained for
proposed methods under appropriate communication noise condition. Moveover,
convergence rates in different orders are comprehensively derived in both
expectation convergence and high probability convergence sense.Comment: 27 page
Residential On-Site Carsharing and Off-Street Parking Policy in the San Francisco Bay Area, Research Report 11-28
In light of rising motorization, transportation planners have increasingly supported alternatives to the indiscriminate use of the car. Off-street parking policy and carsharing have emerged as credible alternatives for discouraging car ownership. This report explores an initiative that could connect these policy fields and build on their synergy: the provision of on-site carsharing service in residential developments. It evaluates the performance of on-site carsharing programs in the San Francisco Bay Area by interviewing developers, planners, and carsharing service providers. Interviews were conducted in four Bay Area cities that support the provision of carsharing as an alternative to the private automobile. Based on these interviews, this report identifies the principal factors contributing to the success or failure of on-site carsharing: the unbundling status of off-street parking in residential developments; ties to off-street parking standards; financial constraints; and the level of coordination among stakeholders. The interviews revealed that on-site carsharing has been accepted by developers, planners, and service providers, particularly in densely-populated, transit-rich communities. Nevertheless, there appears to be a gap between on-site carsharing programs and off-street parking standards, and between carsharing programs and carsharing business operations. The authors recommend that a few models for establishing carsharing policy be tested: a model designed to serve high-density cities with traditional carsharing; and another designed to serve moderately-dense communities, with new carsharing options (e.g., peer-to-peer). In the case of the latter, trip reduction can be achieved through the promotion of alternative modes along major corridors
Amenity or Necessity? Street Standards as Parking Policy, Research Report 11-23
This paper explores the rationales underlying the use of minimum street width requirements to mandate street parking. A survey of 97 cities reveals that this mandate is not a technical necessity based on safety concerns or an amenity reflecting market demand, two common beliefs held by decision-makers. Many residents are likely unwilling to pay for street parking if it is unbundled from housing. The hidden parking policies should be made transparent and subject to public oversight, the double standard between private and public streets should be eliminated, and parking on residential streets should be optional
New Approach on the General Shape Equation of Axisymmetric Vesicles
The general Helfrich shape equation determined by minimizing the curvature
free energy describes the equilibrium shapes of the axisymmetric lipid bilayer
vesicles in different conditions. It is a non-linear differential equation with
variable coefficients. In this letter, by analyzing the unique property of the
solution, we change this shape equation into a system of the two differential
equations. One of them is a linear differential equation. This equation system
contains all of the known rigorous solutions of the general shape equation. And
the more general constraint conditions are found for the solution of the
general shape equation.Comment: 8 pages, LaTex, submit to Mod. Phys. Lett.
Multiparty Quantum Secret Sharing Based on Entanglement Swapping
A multiparty quantum secret sharing (QSS) protocol is proposed by using
swapping quantum entanglement of Bell states. The secret messages are imposed
on Bell states by local unitary operations. The secret messages are split into
several parts and each part is distributed to a party so that no action of a
subset of all the parties but their entire cooperation is able to read out the
secret messages. In addition, the dense coding is used in this protocol to
achieve a high efficiency. The security of the present multiparty QSS against
eavesdropping has been analyzed and confirmed even in a noisy quantum channel.Comment: 5 page
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