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A numerical pressure wave reflection experiment in a two-dimensional liquid and its comparison with experimental results are presented. The liquid is simulated by the pseudo-potential extension of the lattice-Boltzmann method. In the simulation a pressure pulse is produced by a point source and the resulting pressure wave is reflected back by a wettable rigid wall. Negative pressure tail can be observed at the vicinity of the wall/liquid interface. The resulted shape of the positive and the negative pressure wave is compared with experimental results obtained in an electromagnetic shock-wave generator. Good agreement has been found between the experimental and simulation results.

In this paper we calculate the basic thermodynamical quantities for a system of bosonic simple harmonic oscillators (BSHOs) and the corresponding system of fermionic simple harmonic oscillators (FSHOs) using a dispersion relationship similar to cases in general relativity and condensed matter physics. In the FSHO, we see negative temperatures, and in both cases we obtain finally a system of oscillators with only one effective frequency of vibration. Also we see that pressure is less than zero for T$<$T_c where T_c is the critical temperature for bosons.

Dark energy is an elusive concept, which has been introduced two decades ago in order to make the acceleration of the universe a comprehensible phenomenon. However, the nature of this energy is far from being understood, both from a fundamental as well as an observational way. In this work, we study cosmological consequences of the existence of particles (which we called “ewkons” in a previous work) which are quasi distinguishable, obey unorthodox statistics, and have an equation of state similar to many existent dark energy candidates (including negative relation between pressure and energy density). We find an effective scalar field description of this ewkon fluid, and obtain cosmological solutions for the dark energy-dominated epoch. This can be considered as a one-parameter class of dark energy models.

Most artificial muscles currently in existence driven by negative pressure are in the form of origami. Their contractions are directly attained by extracting the air internal, and obtaining a differential pressure with the external (0.101MPa). During contraction, the artificial muscle simultaneously encounters radial and axial pressures provided by the atmosphere. If the muscle is isotropic, the radial pressure would make the artificial muscle unreliable, which would weaken the muscle’s contraction, including contraction force, ratio, and speed. This paper first introduces the contraction theory and dysfunction of the muscle. Then, an optimization method is proposed as local reinforcement, aiming at the muscle’s dysfunction that may occur during contraction. Then, by analyzing and comparing the optimization effects on the muscle contraction force and deformation with different reinforced regions, the endplates and crests are determined to be appropriate. Subsequently, the deformations of the reinforced regions when stressed are analyzed, and the adequate reinforcement dimensions are confirmed. Finally, the muscle’s model passes the simulation for ensuring its contraction without dysfunction, demonstrating the rationality of the reinforcement method proposed in this paper. Hereby, the goal of reinforcing the muscle’s radial stiffness is achieved, making the artificial muscle generate an optimal contraction performance.

The non-destructive inspection of large concrete walls is still an unsolved problem. One possible technique is to use driven wheels for the propulsion and a vacuum system for the adhesion. The seals for the vacuum chambers are slipping over the rough surface, therefore it is not guaranteed that the chambers are always airproof. Especially over concrete walls a special seal construction must be found to make the adhesion more safe. On the other side the propulsion system must be able to produce enough force for carrying and accelerating the robot to a suitable velocity.

This paper will present the climbing robot CROMSCI which uses the described techniques. The propulsion system consists of three omni directional driven wheels which are airproof and completely rotatable and has been presented in earlier papers before. For adhesion a vacuum system of seven controllable vacuum chambers and one reservoir chamber is used. This system including chambers and seals will be discussed in more detail. The rough and sharp-edged surface of concrete walls cause strong requirements to the sealing concerning leak tightness and attrition. Therefore, each sealing must be flexible to allow a good adaption to the ground but also let the robot slip when the wheels are turning.

The non-destructive inspection of large concrete walls via robotic systems is no longer an unsolved problem. This paper will present first results with the climbing prototype CROMSCI which uses a vacuum system of seven controllable vacuum chambers and an omnidirectional drive to move and cling to vertical concrete surfaces. This platform is able to move and inspect vertical surfaces safely, fast and cost-efficient. The technician can check the building more safe without any telescopic crane or other complex access devices via remote control or semi-autonomously.

Climbing on vertical concrete structures like bridge pylons or dams is still a great challenge for autonomous robots. This paper presents the force- and traction control system of the climbing robot Cromsci which uses a negative pressure system for adhesion and driven wheels for propulsion. Especially in vertical environments the propulsion system must be able to produce enough force for carrying and accelerating the robot contrarily to gravity. Slippery of the wheels must be minimized due to abrasion and uncontrollable movements of the robotic system. This can be done by measuring upcoming forces and taking them into account for a traction control system (TCS). Another problem may occur because of slightly different wheel orientations which will result in increasing shear forces. We will show a control system to minimize these errors and experimental results which demonstrate its functionality.