scholarly journals Hubble parameter in f(R)-gravity

2020 ◽  
pp. 22-25
Author(s):  
V. Zhdanov ◽  
O. Stashko
Keyword(s):  
Hubble Parameter ◽  
Degrees Of Freedom ◽  
Order Differential Equation ◽  
Small Deviation ◽  
Hubble Constant ◽  
The Other ◽  
Friedmann Equations ◽  
Constant Tension ◽  
Isotropic Cosmology ◽  
Homogeneous Background

In view of the famous problem with the “Hubble constant tension” there is a number of approaches to modify the cosmological equations and correspondingly modify Hubble parameter H(z) in order to to relieve the tension between the “early” and “late” Hubble constants. f(R)– gravity is one of such possible modifications. We discuss how to choose the Lagrangian in the f(R)– gravity on account of observational data within the homogeneous isotropic cosmology. The equation is obtained that enable us to derive f(R) for given Hubble parameter H(z). This yields a second order differential equation with corresponding degrees of freedom. If H(z) corresponds to that obtained from usual Friedmann equations, this equation yields a condition for f(R) to mimic the observable quantities of the standard ΛCDM with the above-mentioned freedom. To reduce this freedom on needs additional considerations, which involve the other observable quantities, such as those which appear in considerations of cosmological perturbations on the isotropic and homogeneous background. Also, we consider the reverse problem to find for given f(R). This is fulfilled within an approximation in case of small deviation of f(R) from the General Relativity value.

Footbridges as an important part of a system: the context as an experience

2021 ◽  
Author(s):  
Toon Maas ◽  
Mohamad Tuffaha ◽  
Laurent Ney
Keyword(s):  
Design Process ◽  
Degrees Of Freedom ◽  
The Other ◽  
Infrastructure Projects ◽  
Good Design ◽  
Cultural Processes ◽  
The Relationship

<p>“A bridge has to be designed”. Every bridge is the exploration of all degrees of a freedom of a project: the context, cultural processes, technology, engineering and industrial skills. A successful bridge aims to dialogue with these degrees of freedom to achieve a delicate equilibrium, one that invites the participation of its users and emotes new perceptions for its viewers. In short, a good design “makes the bridge talk.”</p><p>Too often, the bridge, as an object, is reduced to its functionality. Matters of perceptions and experiences of the users are often not considered in the design process; they are relegated to levels of chance or treated as simple decorative matter. The longevity of infrastructure projects, in general, and bridges, in particular, highlights the deficiencies of such an approach. The framework to design bridges must include historical, cultural, and experiential dimensions. Technology and engineering are of paramount importance but cannot be considered as “an end in themselves but a means to an end”. This paper proposes to discuss three projects by Ney &amp; Partners that illustrate such a comprehensive exploration approach to footbridge design: the Poissy and Albi crossings and the Tintagel footbridge.</p><p>The footbridges of Poissy and Albi dialogue most clearly with their historical contexts, reconfiguring the relationship between old and new in the materiality and typology use. In Tintagel, legend replaces history. Becoming a metaphor for the void it crosses, the Tintagel footbridge illustrates the delicate dialogue of technology and engineering on one side and imagination and experience on the other.</p>

scholarly journals Analysis of the Angular Dependence of Time Delay in Gravitational Lensing

2018 ◽  
Author(s):  
Nicola Alchera ◽  
Marco Bonici ◽  
Roberta Cardinale ◽  
Alba Domi ◽  
Nicola Maggiore ◽  
...  
Keyword(s):  
Time Delay ◽  
Angular Dependence ◽  
Gravitational Potential ◽  
Gravitational Lensing ◽  
Degrees Of Freedom ◽  
Hubble Constant ◽  
Smoothness Condition ◽  
Central Potential ◽  
Alternative Formula

We consider an alternative formula for time delay in gravitational lensing. Imposing a smoothness condition on the gravitationally deformed paths followed by the photons from the source to the observer, we show that our formula displays the same degrees of freedom of the standard one. In addition to this, it is shown that the standard expression for time delay is recovered when small angles are involved. These two features strongly support the claim that the formula for time delay studied in this paper is the generalization to arbitrary angles of the standard one, which is valid at small angles. This could therefore result in a useful tool in view of softening the known discrepancy between the various estimates of the Hubble constant. As an aside, two interesting consequences of our proposal for time delay are discussed: the existence of a constraint on the gravitational potential generated by the lens and a formula for the mass of the lens in the case of central potential.

scholarly journals Soldati e neuropsichiatria nell'Italia della Grande Guerra

2020 ◽  
Author(s):  
Marco Romano
Keyword(s):  
Mental Illness ◽  
Professional Ethics ◽  
Critical Reflection ◽  
The Other ◽  
Military Psychiatry ◽  
Constant Tension ◽  
War Effort ◽  
The One ◽  
The Great War ◽  
The Relationship

Against the backdrop of a critical reflection on the psychiatric concepts of organicism and predisposition to mental illness, the research investigates the relationship between psychiatry and the Great War from a perspective that considers the complexity of the orientations assumed by both the Italian alienists on war pathologies and the health practices implemented towards soldiers. The study highlights the comparison/clash between two totally different approaches forced to coexist during the conflict: on one side, the one from military psychiatry, and on the other the distinctive one from civil asylums. The two perspectives were not always clearly separated, but it is possible to detect a constant tension between the duties towards the war effort and the professional ethics dictated by the neuropsychiatric discipline.

scholarly journals Generalized emergent dark energy model and the Hubble constant tension

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Weiqiang Yang ◽  
Eleonora Di Valentino ◽  
Supriya Pan ◽  
Arman Shafieloo ◽  
Xiaolei Li
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Hubble Constant ◽  
Energy Model ◽  
Constant Tension

Miniaturized Dual-Band Bandpass Filter Using Embedded Dual-Mode Resonator with Controllable Bandwidths

Frequenz ◽  
2016 ◽  
Vol 70 (9-10) ◽  
Author(s):  
Chuanming Zhu ◽  
Jin Xu ◽  
Wei Kang ◽  
Zhenxin Hu ◽  
Wen Wu
Keyword(s):  
Insertion Loss ◽  
Degrees Of Freedom ◽  
Bandpass Filter ◽  
The Other ◽  
Dual Band ◽  
Dual Mode ◽  
Transmission Zeros ◽  
Low Insertion Loss ◽  
Multiple Transmission ◽  
Mode Resonator

AbstractIn this paper, a miniaturized dual-band bandpass filter (DB-BPF) using embedded dual-mode resonator (DMR) with controllable bandwidths is proposed. Two passbands are generated by two sets of resonators operating at two different frequencies. One set of resonators is utilized not only as the resonant elements that yield the lower passband, but also as the feeding structures with source-load coupling to excite the other to produce the upper passband. Sufficient degrees of freedom are achieved to control the center frequencies and bandwidths of two passbands. Moreover, multiple transmission zeros (TZs) are created to improve the passband selectivity of the filter. The design of the filter has been demonstrated by the measurement. The filter features not only miniaturized circuit sizes, low insertion loss, independently controllable central frequencies, but also controllable bandwidths and TZs.

A Robotic Cell for Embedding Prefabricated Components in Extrusion-Based Additive Manufacturing

2020 ◽  
Author(s):  
Yeo Jung Yoon ◽  
Oswin G. Almeida ◽  
Aniruddha V. Shembekar ◽  
Satyandra K. Gupta
Keyword(s):  
Additive Manufacturing ◽  
Degrees Of Freedom ◽  
Robotic Manipulators ◽  
The Other ◽  
Robotic Arm ◽  
Robotic Cell ◽  
Material Extrusion ◽  
Surface Polishing ◽  
Pick And Place ◽  
6 Degrees Of Freedom

Abstract By attaching a material extrusion system to a robotic arm, we can deposit materials onto complex surfaces. Robotic manipulators can also maximize the task utility by performing other tasks such as assembly or surface polishing when they are not in use for the AM process. We present a robotic cell for embedding prefabricated components in extrusion-based AM. The robotic cell consists of two 6 degrees of freedom (DOF) robots, an extrusion system, and a gripper. One robot is used for printing a part, and the other robot takes a support role to pick and place the prefabricated component and embed it into the part being printed. After the component is embedded, AM process resumes, and the material is deposited onto the prefabricated components and previously printed layers. We illustrate the capabilities of the system by fabricating three objects.

A Family of 3-DOF Translational Parallel Manipulators1

2003 ◽  
Vol 125 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Marco Carricato ◽  
Vincenzo Parenti-Castelli
Keyword(s):  
Degrees Of Freedom ◽  
Translational Motion ◽  
Parallel Manipulators ◽  
Geometric Interpretation ◽  
The Other ◽  
Six Degrees Of Freedom ◽  
Revolute Joints ◽  
Rotational Degrees Of Freedom

This article addresses parallel manipulators with fewer than six degrees of freedom, whose use may prove valuable in those applications in which a higher mobility is uncalled for. In particular, a family of 3-dof manipulators containing only revolute joints or at the most revolute and prismatic ones is studied. Design and assembly conditions sufficient to provide the travelling platform with a pure translational motion are determined and two sub-families that fulfill the imposed constraint are found: one is already known in the literature, while the other is original. The new architecture does not exhibit rotation singularities, i.e., configurations in which the platform gains rotational degrees of freedom. A geometric interpretation of the translation singularities is provided.

scholarly journals Relating the deBroglie and Compton Wavelengths to the Velocity of Light?

2018 ◽  
Vol 10 (4) ◽  
pp. 102
Author(s):  
Gordon R. Kepner
Keyword(s):  
Order Differential Equation ◽  
Free Particle ◽  
The Other ◽  
Time Dependent ◽  
Uncertainty Relations ◽  
Fundamental Relation ◽  
Compton Wavelength ◽  
Velocity Of Light ◽  
Velocity Wave ◽  
Empirical Constants

No report in the literature has directly described this relation. New constants for particles are presented. One relates to the Compton wavelength, called here the “mass-wave” constant for all particles. The other relates to the deBroglie wavelength, called here the “velocity-wave” constant for a particle. An equation is derived based on these two constants encapsulating a fundamental relation between the matter-states, particle and wave, to the velocity of light. New approaches to the Uncertainty relations are shown. The basic Schrodinger equation is derived from the perspective of a non-dimensional second-order differential equation free of any assumed empirical constants. The resulting time-dependent wave equation for a free particle was then expressed in terms of the particle velocity and deBroglie wavelength.

scholarly journals Bounce Cosmology in Generalized Modified Gravities

Universe ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 74 ◽  
Author(s):  
Georgios Minas ◽  
Emmanuel Saridakis ◽  
Panayiotis Stavrinos ◽  
Alkiviadis Triantafyllopoulos
Keyword(s):  
Scalar Field ◽  
Special Relativity ◽  
Tangent Bundle ◽  
General Class ◽  
Degrees Of Freedom ◽  
Geometrical Structure ◽  
Tensor Structure ◽  
Nonlinear Connection ◽  
Friedmann Equations ◽  
Very Special Relativity

We investigate the bounce realization in the framework of generalized modified gravities arising from Finsler and Finsler-like geometries. In particular, a richer intrinsic geometrical structure is reflected in the appearance of extra degrees of freedom in the Friedmann equations that can drive the bounce. We examine various Finsler and Finsler-like constructions. In the cases of general very special relativity, as well as of Finsler-like gravity on the tangent bundle, we show that a bounce cannot easily be obtained. However, in the Finsler–Randers space, induced scalar anisotropy can fulfil bounce conditions, and bouncing solutions are easily obtained. Finally, for the general class of theories that include a nonlinear connection, a new scalar field is induced, leading to a scalar–tensor structure that can easily drive a bounce. These features reveal the capabilities of Finsler and Finsler-like geometries.

Total Flexibility in Forming Technology by Servo Presses

2014 ◽  
Vol 907 ◽  
pp. 99-112 ◽  
Author(s):  
Jörg Avemann ◽  
Stefan Calmano ◽  
Sebastian Schmitt ◽  
Peter Groche
Keyword(s):  
Mass Production ◽  
Degrees Of Freedom ◽  
Sheet Thickness ◽  
The Other ◽  
Adaptive Control System ◽  
High Productivity ◽  
Forming Technology ◽  
Bending Process ◽  
Product And Process ◽  
Free Bending

In forming technology, uncertainty can arouse from fluctuations in demand scenarios on one hand and in properties of semi-finished parts on the other. These technologies are usually characterized by a high productivity in mass production. However, high development efforts and investment costs for processes and machines lead to a rigid product and process spectrum. One approach to encounter these uncertainties is the introduction of flexibility into forming technologies by enlarging the number of degrees of freedom without drastically reducing productivity. The 3D Servo Press fulfils the mentioned requirements by exceeding free ram motion of conventional servo presses by two rotational ram DoFs. The adaptive control system coordinates the machine motion and controls product properties by model-based algorithms. Possibilities of this approach are demonstrated in a free bending process of a heat dissipater, resulting in uniform product quality despite variations in material, sheet thickness and desired geometry.

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