Clarification of Features of the Wheel Movement with a Perspective Constructive Scheme on a Rail

The article presents the continuation of studies of the features of the wheel movement the traditional and perspective constructive scheme on a rail. Unlike the traditional design, the perspective constructive scheme of the wheel allows independent relative rotation of the support surface wheel and of its guide surface (flange) relative to their common axis of rotation. Previous authors’ works did not take into account the influence of the level of slippage in the main contact of the wheel with the rail on the value of the slippage rate in its flange contact. This article further examines the influence of this factor for both wheel designs. The results of the presented studies confirm the possibility of reducing slippage in the flange contact with the rail for a wheel of a promising design scheme in comparison with a traditional wheel. Reducing the power of friction forces in the contact of the wheel flange of a promising design scheme will reduce the resistance to movement of such a wheel along the rail, especially in curved track sections.

Defending Gentrification as a Valid Collective Conception: Utilizing the Metanarrative of “Suburbia” as a Common Axis for the Diversity of Middle-Class Reurbanization Projects

A long-standing problem in gentrification research is the increasingly diverse array of interests and agendas in the renewal of the inner city; their diversity has frustrated many scholars with respect to the collective characterization and comprehension of the phenomenon. Consequently, others have questioned the validity of the term “gentrification” itself. This article contends that gentrification is a phenomenon that merits being collectively identified. The relocation of the middle class to the urban core has been portrayed in terms of actors and agendas, places and processes. These criteria have long since been inadequate to collectively rationalize gentrification in anything other than strictly spatial terms. But when suburbia is perceived as a metanarrative, the collective character of gentrification becomes evident; for it is the process of the metanarrative’s systemic erosion in the postmodern era that serves the long-standing desire to find an operant commonality to gentrification’s apparent lack of coherence.

Design of rigid-foldable doubly curved origami tessellations based on trapezoidal crease patterns

This paper presents a mathematical framework for the design of rigid-foldable doubly curved origami tessellations based on trapezoidal crease patterns that can simultaneously fit two target surfaces with rotational symmetry about a common axis. The geometric parameters of the crease pattern and the folding angles of the target folded state are determined through a set of combined geometric and constraint equations. An algorithm to simulate the folding motion of the designed crease pattern is provided. Furthermore, the conditions and procedures to design folded ring structures that are both developable and flat-foldable and stacked folded structures consisting of two layers that can fold independently or compatibly are discussed. The proposed framework has potential applications in designing engineering doubly curved structures such as deployable domes and folded cores for doubly curved sandwich structures on the aircraft.

Nonsymmetrical Flow Compensation Using Hydraulic Accumulator in Direct Driven Differential Cylinder Application

This paper presents a novel hydraulic setup, direct driven hydraulics (DDH), which consists of two pumps on a common axis driven by a servomotor. These pumps are directly connected to each chamber of a differential hydraulic cylinder. The pumps are dimensioned so that the respective nominal sizes corresponds to the expected flows of each cylinder chamber. However, the dimensioning of the pumps are slightly off, leading to an excess rise of pressure in the B-chamber. This paper investigates if the implementation of a hydraulic accumulator can mitigate this mismatch problem. A Matlab/Simulink model was created and utilized for simulating the optimal accumulator parameters for energy efficiency. The optimal alternative was implemented to the research setup and energy efficiency measurements are performed with various loads and different ambient temperatures. The results shows that this solution was a viable alternative and that the energy efficiency of this setup was improved.

Eigenvalues of the Transferences of Gaussian Optical Systems

The problem of how to define an average eye leads to the question of what eigenvalues are possible for ray transferences. This paper examines the set of possible eigenvalues in the simplest possible case, that of optical systems consisting of elements that are stigmatic and centred on a common axis.