Falsification of Einstein’s relativity

In 1915, Einstein published general relativity. In 1916, he published a German language book about relativity, which contained his marble table thought experiment for explaining a continuum. Without realizing it, Einstein introduced a quantized two-dimensional discontinuum geometry and inadvertently falsified the marble table thought experiment continuum, which falsified relativity. The foundations of physics do not now (and never did) include a fundamentally sound relativistic theory to account for macroscopic phenomena. It is well known the success of relativity and its singularity problem indicate general relativity is a first approximation of a more fundamental theory. Combine that indication with the falsification of relativity and it is apparent, without speculation, that relativity is now and always was a first approximation of a more fundamental theory. A possible way forward to the more fundamental theory is developing a discontinuum physics based on the quantized two-dimensional discontinuum geometry or an algebraic version of it. Such discontinuum physics is not presented, because it is beyond the scope of this paper.

Optimum Seeking of Redundant Actuators for M-RCM 3-UPU Parallel Mechanism

The singularity problem brings troubles to the design and application for the parallel mechanism. Currently, redundant actuation is one of the useful methods to solve this singularity problem. However, faced to the numerous joints in a parallel mechanism, how to make a quantitative criterion of seeking the most efficient joints added actuators for letting the mechanism passes through singularity is a necessarily open issue. This paper focuses on a 2R1T 3-UPU (U for universal joint and P for prismatic joint) parallel mechanism (PM) with two rotational and one translational (2R1T) degrees of freedom (DOFs) and the ability of multiple remote centers of motion (M-RCM). The singularity analysis based on the indexes of motion/force transmissibility and constraint shows that this PM has transmission singularity, constraint singularity, mixed singularity and limb singularity. To solve these singular problems, the quantifiable redundancy transmission index (RTI) and the redundancy constraint index (RCI) are proposed for optimum seeking of redundant actuators for this PM. Then the appropriate redundant actuators are selected and the working scheme for redundant actuators near the corresponding singular configuration are given to help the PM passes through the singularity. This research proposes a quantitative criterion to optimum seeking of redundant actuators for the parallel mechanism to solve its singularity.

Mobility analysis of a robotic cardiopulmonary resuscitation device

During chest compressions action, in CPR (CPR), the 2 arms of the rescuer constitute a parallel mechanism. Inspired by this performance, during this study a specific family of lower mobility parallel manipulators by employing a modified version of Delta robot is proposed for chest compressions in rescuing a patient. One of the biggest differences between this mechanism and the Delta parallel mechanism is that the position of the three active connections of the robot relative to each other has changed the geometry of the platforms. Also, it shapes the asymmetrical structure within the robot mechanism and its workspace. Another difference is due to the architectural optimization method considering the mixed performance index, which has been used during this mechanism to achieve a much better compromise between the manipulator dexterity and its workspace. Within the present paper, after introducing the architecture of the robot, a closed-form solution is developed for the kinematic problem and therefore the results are verified using MSC. Adams©. Then Jacobian matrix is generated to gauge the singularity problem of the proposed mechanism. then, the workspace of the robot is investigated and compared with the original Delta mechanism.

No-go theorem for inflation in Ricci-inverse gravity

In this paper, we study the so-called Ricci-inverse gravity, which is a very novel type of fourth-order gravity proposed recently. In particular, we are able to figure out both isotropically and anisotropically inflating universes to this model. More interestingly, these solutions are shown to be free from a singularity problem. However, stability analysis based on the dynamical system method shows that both isotropic and anisotropic inflation of this model turn out to be unstable against field perturbations. This result implies a no-go theorem for both isotropic and anisotropic inflation in the Ricci-inverse gravity.

Inner horizon instability and the unstable cores of regular black holes

Regular black holes with nonsingular cores have been considered in several approaches to quantum gravity, and as agnostic frameworks to address the singularity problem and Hawking’s information paradox. While in a recent work we argued that the inner core is destabilized by linear perturbations, opposite claims were raised that regular black holes have in fact stable cores. To reconcile these arguments, we discuss a generalization of the geometrical framework, originally applied to Reissner-Nordtsröm black holes by Ori, and show that regular black holes have an exponentially growing Misner-Sharp mass at the inner horizon. This result can be taken as an indication that stable nonsingular black hole spacetimes are not the definitive endpoint of a quantum gravity regularization mechanism, and that nonperturbative backreation effects must be taken into account in order to provide a consistent description of the quantum-gravitational endpoint of gravitational stellar collapse.

Non-singular black holes with a zero-shear S-brane

We propose a construction with which to resolve the black hole singularity and enable an anisotropic cosmology to emerge from the inside of the hole. The model relies on the addition of an S-brane to the effective action which describes the geometry of space-time. This space-like defect is located inside of the horizon on a surface where the Weyl curvature reaches a limiting value. We study how metric fluctuations evolve from the outside of the black hole to the beginning of the cosmological phase to the future of the S-brane. Our setup addresses i) the black hole singularity problem, ii) the cosmological singularity problem and iii) the information loss paradox since the outgoing Hawking radiation is entangled with the state inside the black hole which becomes the new universe.

A Fast Method for Calculation of Marine Gravity Anomaly

Gravity data have been playing an important role in marine exploration and research. However, obtaining gravity data over an extensive marine area is expensive and inefficient. In reality, marine gravity anomalies are usually calculated from satellite altimetry data. Over the years, numerous methods have been presented for achieving this purpose, most of which are time-consuming due to the integral calculation over a global region and the singularity problem. This paper proposes a fast method for the calculation of marine gravity anomalies. The proposed method introduces a novel scheme to solve the singularity problem and implements the parallel technique based on a graphics processing unit (GPU) for fast calculation. The details for the implementation of the proposed method are described, and it is tested using the geoid height undulation from the Earth Gravitational Model 2008 (EGM2008). The accuracy of the presented method is evaluated by comparing it with marine shipboard gravity data. Its efficiency is demonstrated through comparison with the conventional sequential method. The tests demonstrate that the proposed method can be employed for accurately calculating marine gravity anomalies and provides an advantage on computational efficiency.

Sliding Mode Variable Impedance Control for 4RRR Redundantly Actuated Parallel Robot

The workspace of parallel robot is limited, and the distribution characteristics of kinematics and force maneuverability are complex in the workspace. In addition, there are often operational singularities. The redundant actuation technology can not only overcome singularity problem of force maneuverability of parallel mechanism, but also eliminate the clearance of the mechanism, dynamically adjust the operating stiffness, realize the optimized operation of energy consumption, etc. In this paper, with the goal of realizing dexterous dynamic output control, the variable impedance control technology of redundantly actuated parallel robot based on operation space is studied. Compared with the traditional invariable impedance control, the variable impedance control can adapt to the change of unknown environment by time-varying controlling parameters, which provides the possibility to realize the polishing of complex curved surfaces and thin-walled parts, assembly task and improves the performance of the system and the machining quality of the parts. In order to avoid the influence of unmodeled errors and external interferences on the system, based on the sliding mode control (SMC) strategy, the variable impedance control (VIC) in the operating space of 4RRR redundantly actuated parallel robot (4RAPR) is proposed. The robust stability of the closed-loop system is analyzed and verified by Matlab programming simulation.

Viscous Matter in FRW Cosmology

We investigate the dynamics of dust matter with bulk viscosity effects. We explored the analogy dynamical problem to Chaplygin gas. Due to this analogy we give exact solutions for the FRW cosmology with viscosity coefficient parameterized by the Belinskii–Khalatnikov power law dependence with respect to energy density. These exact solutions are given in the form of hypergeometrical functions. We proved simple theorem which illustrated as viscosity effects can solved the initial singularity problem present in standard cosmological model.