A Conceptual Model for the Origin of the Cutoff Parameter in Exotic Compact Objects

A Black Hole (BH) is a spacetime region with a horizon and where geodesics converge to a singularity. At such a point, the gravitational field equations fail. As an alternative to the problem of the singularity arises the existence of Exotic Compact Objects (ECOs) that prevent the problem of the singularity through a transition phase of matter once it has crossed the horizon. ECOs are characterized by a closeness parameter or cutoff, ϵ, which measures the degree of compactness of the object. This parameter is established as the difference between the radius of the ECO’s surface and the gravitational radius. Thus, different values of ϵ correspond to different types of ECOs. If ϵ is very big, the ECO behaves more like a star than a black hole. On the contrary, if ϵ tends to a very small value, the ECO behaves like a black hole. It is considered a conceptual model of the origin of the cutoff for ECOs, when a dust shell contracts gravitationally from an initial position to near the Schwarzschild radius. This allowed us to find that the cutoff makes two types of contributions: a classical one governed by General Relativity and one of a quantum nature, if the ECO is very close to the horizon, when estimating that the maximum entropy is contained within the material that composes the shell. Such entropy coincides with the Bekenstein–Hawking entropy. The established cutoff corresponds to a dynamic quantity dependent on coordinate time that is measured by a Fiducial Observer (FIDO). Without knowing the details about quantum gravity, parameter ϵ is calculated, which, in general, allows distinguishing the ECOs from BHs. Specifically, a black shell (ECO) is undistinguishable from a BH.

Cooperative Multiagent Deep Deterministic Policy Gradient (CoMADDPG) for Intelligent Connected Transportation with Unsignalized Intersection

Unsignalized intersection control is one of the most critical issues in intelligent transportation systems, which requires connected and automated vehicles to support more frequent information interaction and on-board computing. It is very promising to introduce reinforcement learning in the unsignalized intersection control. However, the existing multiagent reinforcement learning algorithms, such as multiagent deep deterministic policy gradient (MADDPG), hardly handle a dynamic number of vehicles, which cannot meet the need of the real road condition. Thus, this paper proposes a Cooperative MADDPG (CoMADDPG) for connected vehicles at unsignalized intersection to solve this problem. Firstly, the scenario of multiple vehicles passing through an unsignalized intersection is formulated as a multiagent reinforcement learning (RL) problem. Secondly, MADDPG is redefined to adapt to the dynamic quantity agents, where each vehicle selects reference vehicles to construct a partial stationary environment, which is necessary for RL. Thirdly, this paper incorporates a novel vehicle selection method, which projects the reference vehicles on a virtual lane and selects the largest impact vehicles to construct the environment. At last, an intersection simulation platform is developed to evaluate the proposed method. According to the simulation result, CoMADDPG can reduce average travel time by 39.28% compared with the other optimization-based methods, which indicates that CoMADDPG has an excellent prospect in dealing with the scenario of unsignalized intersection control.

What kind of nation state will Greenland be? Securitization theory as a strategy for analyzing identity politics

Arctic geopolitics is a moving target - and Greenland, determined to emerge as a sovereign nation state, is a particularly dynamic quantity. The choices currently made in language policy about how to prioritize the Greenlandic, Danish, and English languages will be putting Greenland on very different routes towards and beyond independence. The article modifies the analytical strategy prescribed by Copenhagen School Securitization Theory to produce a nuanced picture of national identity politics, the tensions involved, and scenarios for the future. Analysis of the 2002 and 2016 debates on language supplements the received image of what constitutes Greenlandic identity, centered on language and iconic material cultural practices, with conspicuously modern elements like democracy and welfare. Advancing formally from 'home rule' to 'self-government' has shifted the debate towards material challenges - prompting a more prominent role for the English language, in turn pointing Greenland towards new alliances in Arctic geopolitics.

Intermolecular Study of Adansonia Digitata (AnD) Binary Liquid Mixture

The resistance of a liquid to flow and the molecules of a liquid exhibit intermolecular attraction for each another and are called its viscosity and surface tension. Surface tension is measured as the energy required to increase the surface area of a liquid by a unit of area. Viscosity is governed by the strength of intermolecular forces and especially by the shapes of the molecules of a liquid. The surface tension of a liquid results from an imbalance of intermolecular attractive forces, the cohesive forces between molecules. The change in free energy during a reaction, it is a direct measure of the amount disorder that is created in the universe when the reaction occurs. A thermo-dynamic quantity combining enthalpy and entropy into a single value is called the Gibbs free energy ΔG. The value of ΔG for a reaction is a direct measure of how far the reaction is from equilibrium. The large negative value for ATP hydrolysis in a cell merely reflects the fact that cells keep the ATP hydrolysis reaction as much as 10 orders of magnitude away from the equilibrium. The change of free energy is equal to the sum of its enthalpy plus the product of the temperature and entropy of the system. The characteristic time for a system to reach an equilibrium condition after a disturbance is called relaxation time.Adansonia Digitata(AnD) fruit collected from Mandav District Dhar (M.P.). The entire chemical used in this study analytical grade.

Dynamic Differential Pressure Effects on Drilling of Permeable Formations

In the mathematical modeling of bit penetration rate for tri-cone roller bits in permeable formations, virtually all of the current techniques assume that the differential pressure between the bottom-hole wellbore pressure and the formation is a “static” value. This work shows that the appropriate differential pressure is a dynamic quantity, because for overbalanced drilling, fluid filtrate from the wellbore requires a finite time to flow into the formation, producing a changing pressure gradient ahead of the bit. Moreover, this dynamic gradient is directly dependent upon the rate of drill bit penetration, which is in turn dependent upon the dynamic gradient itself. Accordingly, coupled penetration rate and dynamic gradient equations must be solved, which frequently result in the prediction of higher drilling penetration rates than when the static gradient is used. The appropriate dynamic differential pressure equations are developed and applied to an example drilling situation. It is shown that with water-based drilling fluids, for rock with permeability greater than a few microdarcies at virtually all penetration rates, and for penetration rates less than 3 m/h (9.84 ft/h) at permeabilities greater than 1 μd (microdarcy), the dynamic differential pressure is significantly less than the static differential pressure. Accordingly, using the conventional static differential pressure results in the prediction of penetration rates that are much too low. Moreover, using measured penetration rates from the field, the conventional approach yields predicted in-situ rock strength that is much too high.