On the constraint structure of vacuum energy sequestering

A diagramming method called Propositional Constraint (PC) graphing was developed as an aid for tasks involving argumentation, planning, and design. Motivated by several AI models of defeasible (or non- monotonic) reasoning, PC graphs were designed to represent knowledge according to an analogical framework in which constraints (e.g., evidence, goals, system constraints) may elicit or deny possibilities (e.g., explanations, decisions, behaviors). In cases of underspecification, an absence of constraints yields uncertainty and competition among plausible outcomes. In cases of overspecification, no plausible outcome is yielded until one of the constraints is amended or forfeited. This framework shares features with theoretical models of reasoning and argumentation, but despite its intuitiveness and applicability, we know of no modeling language or graphical aid that explicitly depicts this defeasible constraint structure. We describe the syntax and semantics for PC graphing and then illustrate potential uses for it.

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An Electrostatic Self-Excited Resonator with Pre-Tension/Pre-Compression Constraint for Active Rotation Control

Micromachines ◽

10.3390/mi12060650 ◽

2021 ◽

Vol 12 (6) ◽

pp. 650

Author(s):

Ruide Yun ◽

Yangsheng Zhu ◽

Zhiwei Liu ◽

Jianmei Huang ◽

Xiaojun Yan ◽

...

Keyword(s):

Maximum Velocity ◽

Flapping Wings ◽

Variable Velocity ◽

Beam Length ◽

Dc Voltage ◽

Middle Position ◽

Simply Supported ◽

Maximum Value ◽

Constraint Structure

We report a novel electrostatic self-excited resonator driven by DC voltage that achieves variable velocity-position characteristics via applying the pre-tension/pre-compression constraint. The resonator consists of a simply supported micro-beam, two plate electrodes, and two adjustable constraint bases, and it can be under pre-compression or pre-tension constraint by adjusting the distance L between two constraint bases (when beam length l > L, the resonator is under pre-compression and when l < L, it is under pre-tension). The oscillating velocity of the beam reaches the maximum value in the position around electrodes under the pre-compression constraint and reaches the maximum value in the middle position between two electrodes under the pre-tension condition. By changing the constraint of the microbeam, the position of the maximum velocity output of the oscillating beam can be controlled. The electrostatic self-excited resonator with a simple constraint structure under DC voltage has great potential in the field of propulsion of micro-robots, such as active rotation control of flapping wings.

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Weighing the vacuum energy

Physical Review D ◽

10.1103/physrevd.103.084032 ◽

2021 ◽

Vol 103 (8) ◽

Author(s):

Enrique Alvarez ◽

Jesus Anero ◽

Raquel Santos-Garcia

Keyword(s):

Vacuum Energy

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How low can vacuum energy go when your fields are finite-dimensional?

International Journal of Modern Physics D ◽

10.1142/s0218271819440061 ◽

2019 ◽

Vol 28 (14) ◽

pp. 1944006

Author(s):

ChunJun Cao ◽

Aidan Chatwin-Davies ◽

Ashmeet Singh

Keyword(s):

Field Theory ◽

Quantum Field Theory ◽

Degrees Of Freedom ◽

Vacuum Energy ◽

Quantum Field ◽

Locally Finite ◽

Finite Dimensional ◽

Finite Dimensionality ◽

Klein Gordon ◽

Dimensional Version

According to the holographic bound, there is only a finite density of degrees of freedom in space when gravity is taken into account. Conventional quantum field theory does not conform to this bound, since in this framework, infinitely many degrees of freedom may be localized to any given region of space. In this paper, we explore the viewpoint that quantum field theory may emerge from an underlying theory that is locally finite-dimensional, and we construct a locally finite-dimensional version of a Klein–Gordon scalar field using generalized Clifford algebras. Demanding that the finite-dimensional field operators obey a suitable version of the canonical commutation relations makes this construction essentially unique. We then find that enforcing local finite dimensionality in a holographically consistent way leads to a huge suppression of the quantum contribution to vacuum energy, to the point that the theoretical prediction becomes plausibly consistent with observations.

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Thermal Casimir effect with general boundary conditions

The European Physical Journal C ◽

10.1140/epjc/s10052-020-8348-1 ◽

2020 ◽

Vol 80 (8) ◽

Author(s):

J. M. Muñoz-Castañeda ◽

L. Santamaría-Sanz ◽

M. Donaire ◽

M. Tello-Fraile

Keyword(s):

Boundary Conditions ◽

Vacuum Energy ◽

Casimir Effect ◽

Quantum Field ◽

Quantum Vacuum ◽

Parallel Plates ◽

Casimir Forces ◽

Thermal Correction ◽

Frequency Independent ◽

Scalar Quantum

Abstract In this paper we study the system of a scalar quantum field confined between two plane, isotropic, and homogeneous parallel plates at thermal equilibrium. We represent the plates by the most general lossless and frequency-independent boundary conditions that satisfy the conditions of isotropy and homogeneity and are compatible with the unitarity of the quantum field theory. Under these conditions we compute the thermal correction to the quantum vacuum energy as a function of the temperature and the parameters encoding the boundary condition. The latter enables us to obtain similar results for the pressure between plates and the quantum thermal correction to the entropy. We find out that our system is thermodynamically stable for any boundary conditions, and we identify a critical temperature below which certain boundary conditions yield attractive, repulsive, and null Casimir forces.

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The Geometrical Feature Recognition Method of Part Drawing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.415-417.523 ◽

2011 ◽

Vol 415-417 ◽

pp. 523-526

Author(s):

Yan Dong ◽

Mei Li

Keyword(s):

Feature Recognition ◽

Graph Matching ◽

Geometric Feature ◽

Recognition Method ◽

Recognition Mechanism ◽

Chemical Database ◽

Geometry Feature ◽

Constraint Structure ◽

Geometric Elements ◽

Fine Tune

This paper put forward a geometry feature recognition method of part drawing based on graph matching. Describe the constraints structure of geometric feature in geometric elements and those constraint relationships. Match sub-graph in contour closure graphics and those combination. Using linear symbol notation of chemical compounds in chemical database for reference, encode to constraint structure of geometry graphics, establish recognition mechanism of geometric characteristics by structure codes. Taking the fine-tune screw and fork parts for example, this method has been proved to be effective.

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TIME, VACUUM ENERGY, AND THE COSMOLOGICAL CONSTANT

International Journal of Modern Physics D ◽

10.1142/s0218271809015928 ◽

2009 ◽

Vol 18 (14) ◽

pp. 2265-2268 ◽

Cited By ~ 1

Author(s):

VIQAR HUSAIN

Keyword(s):

Quantum Gravity ◽

Cosmological Constant ◽

Vacuum Energy ◽

Cosmological Constant Problem ◽

Problem Of Time ◽

The Relationship

We describe a link between the cosmological constant problem and the problem of time in quantum gravity. This arises from examining the relationship between the cosmological constant and vacuum energy in light of nonperturbative formulations of quantum gravity.

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LOCAL CONTRIBUTION OF A QUANTUM CONDENSATE TO THE VACUUM ENERGY DENSITY

Modern Physics Letters A ◽

10.1142/s0217732303009812 ◽

2003 ◽

Vol 18 (10) ◽

pp. 683-690 ◽

Cited By ~ 3

Author(s):

GIOVANNI MODANESE

Keyword(s):

Energy Density ◽

Vacuum Energy ◽

Casimir Effect ◽

Landau Equation ◽

Vacuum Energy Density ◽

Negative Effects ◽

Ginzburg Landau ◽

Physical Conditions ◽

Local Contribution ◽

Gravitational Vacuum

We evaluate the local contribution gμνL of coherent matter with Lagrangian density L to the vacuum energy density. Focusing on the case of superconductors obeying the Ginzburg–Landau equation, we express the relativistic invariant density L in terms of low-energy quantities containing the pairs density. We discuss under which physical conditions the sign of the local contribution of the collective wave function to the vacuum energy density is positive or negative. Effects of this kind can play an important role in bringing the local changes in the amplitude of gravitational vacuum fluctuations — a phenomenon reminiscent of the Casimir effect in QED.

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