Innovative elastomeric shear leg mount concepts for quasi-zero stiffness isolation

Passive vibration isolation may be a cost-effective solution to isolate a supported system containing a source and/or receiver from the supporting structure. The standard linear theory suggests a low-stiffness joint to create a mobility mismatch in the transmission path, but this solution may lead to large amplitude motions in the supported system. To achieve both motion control and isolation with the same mount and without compromising either objective, an innovative, nonlinear mount concept is proposed. Taking advantage of geometric nonlinearity for large displacements, a quasi-zero stiffness is generated by exploiting the interaction between the nonlinear mechanisms that govern the motion of a number of inclined shear legs. For example, a three-regime stiffness profile is created, including a medium-stiffness preload regime, a quasi-zero stiffness isolation regime, and a high-stiffness motion control regime. This concept offers significant benefits compared with a more conventional compromise approach in that low-amplitude vibrations are exceptionally isolated while large amplitude transient motions are controlled. Illustrative computational examples will be presented to support the underlying linear and nonlinear design principles. Limiting cases will be discussed as well.

Grid-based Genetic Operators for Graphical Layout Generation

Graphical user interfaces (GUIs) have gained primacy among the means of interacting with computing systems, thanks to the way they leverage human perceptual and motor capabilities. However, the design of GUIs has mostly been a manual activity. To design a GUI, the designer must select its visual, spatial, textual, and interaction properties such that the combination strikes a balance among the relevant human factors. While emerging computational-design techniques have addressed some problems related to grid layouts, no general approach has been proposed that can also produce good and complete results covering color-related decisions and other nonlinear design objectives. Evolutionary algorithms are promising and demonstrate good handling of similar problems in other conditions, genetic operators, depending on how they are designed. But even these approaches struggle with elements' overlap and hence produce too many infeasible candidate solutions. This paper presents a new approach based on grid-based genetic operators demonstrated in a non-dominated sorting genetic algorithm (NSGA-III) setting. The operators use grid lines for element positions in a novel manner to satisfy overlap-related constraints and intrinsically improve the alignment of elements. This approach can be used for crossovers and mutations. Its core benefit is that all the solutions generated satisfy the no-overlap requirement and represent well-formed layouts. The new operators permit using genetic algorithms for increasingly realistic task instances, responding to more design objectives than could be considered before. Specifically, we address grid quality, alignment, selection time, clutter minimization, saliency control, color harmony, and grouping of elements.

The Transformative Potential of Ruins: A Tool for a Nonlinear Design Perspective in Adaptive Reuse

In recent years, the heritage preservation debate has seen a growing interest in emerging theories in which the concept of potential plays an essential role. Starting from the assumption that memory is an evolving mental construct, the present paper introduces the concept of “transformative potential” in existing buildings. This novel concept regards the inevitability of loss and the self-destructive potential as part of the transformation of each building. The “transformative potential” is defined here as the relationship between spatial settings and material consistency. This research hypothesizes five “transformative potential” types by analyzing five best-practices adapted ruins in the last 15 years. The analysis integrates quantitative and qualitative research methods: morphological analysis (dimensional variations, critical redrawing, configuration patterns) and decay stages evaluation (shearing layers analysis, adaptation approaches). The goal is to test the “transformative potential” effectiveness in outlining patterns between specific stages of decay and adaptive design projects. Adaptation projects may actualize this potential in a specific time through incremental and decremental phases, outlining a nonlinear relationship between decay and memory. The study provides insights for future research on adapting existing buildings in a particular decay stage.

Design of Minimum Nonlinear Distortion Reconfigurable Antennas for Next-Generation Communication Systems

Nonlinear effects in the radio front-end can degrade communication quality and system performance. In this paper we present a new design technique for reconfigurable antennas that minimizes the nonlinear distortion and maximizes power efficiency through the minimization of the coupling between the internal switching ports and the external feeding ports. As a nonlinear design and validation instance, we present the nonlinear characterization up to 50 GHz of a PIN diode commonly used as a switch for reconfigurable devices in the microwave band. Nonlinear models are extracted through X-parameter measurements supported by accurate calibration and de-embedding procedures. Nonlinear switch models are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large-signal regime and are further used to predict the measured nonlinearities of a reconfigurable antenna. These models have the desired particularity of being integrated straightforwardly in the internal multi-port method formulation, which is used and extended to account for the power induced on the switching elements. A new figure of merit for the design of reconfigurable antennas is introduced—the power margin, that is, the power difference between the fed port and the switching elements, which combined with the nonlinear load models directly translates into nonlinearities and power-efficiency-related metrics. Therefore, beyond traditional antenna aspects such as port match, gain, and beam orientation, switch power criteria are included in the design methodology. Guidelines for the design of reconfigurable antennas and parasitic layers of minimum nonlinearity are provided as well as the inherent trade-offs. A particular antenna design suitable for 5G communications in the 3.5 GHz band is presented according to these guidelines, in which the specific switching states for a set of target performance metrics are obtained via a balancing of the available figures of merit with multi-objective separation criteria, which enables good control of the various design trade-offs. Average Error Vector Magnitude (EVM) and power efficiency improvement of 12 and 6 dB, respectively, are obtained with the application of this design approach. In summary, this paper introduces a new framework for the nonlinear modeling and design of reconfigurable antennas and provides a set of general-purpose tools applicable in cases beyond those used as examples and validation in this work. Additionally, the use of these models and guidelines is presented, demonstrating one of the most appealing advantages of the reconfigurable parasitic layer approach, their low nonlinearity.

Methods of Mathematical Modeling of Automated Machine Systems of Multi-Nomenclature Production

Automated machine tool systems for multi-product manufacturing were designed for processing parts of a certain nomenclature, which includes separate groups of parts, united by the design, technological, organizational and economic properties. To reduce the number of options in the structure of an automated machine tool system, a target nonlinear design function was applied. Technological conditions were formulated in such a way as to allow synthesizing alternative structures of the designed automated system. At this stage, a matrix of relations was built and a formalized description of technological conditions was given. Specific and generalized technological conditions, which take into account the graph of relations and compatibility condition formulated for any pair of elements, were considered. The article discusses the generalized technological conditions obtained on the basis of the synthesis of compatibility and follow-up properties. The existence of generalized technological conditions for the elements of the automated system of the same name was assessed. The interaction of the elements of an automated system during processing, when the condition of the following and compatibility of technological parameters are met, was studied. By analyzing the functional and technological structure of an automated machine tool system for multi-product manufacturing, the key relationships between its main elements were determined, and the technological environment, a key subject of the system research, was identified.

Planar Dynamics of a Motorcycle: Influence of Vibration Isolation System Nonlinearity

This paper investigates the influence of the nonlinearities of a vibration isolation system on the planar dynamics of a motorcycle. The use of a nonlinear isolation system is often necessitated by design and packaging constraints. Although the use of a vibration isolation system is uncommon in motorcycles, it is used in some cases to enhance ride comfort by mitigating vibrations transmitted to the rider due to shaking forces. In such cases, the handling of the motorcycle can be influenced due to the coupled dynamics of the rear unsprung mass and the swing arm. In this paper, a stochastic analysis has been performed by using the statistical linearization method to specifically examine nonlinearities associated with the vibration isolation system. An eight degree-of-freedom planar model has been developed, and each isolator is represented by a modified multi-axial Kelvin-Voigt model. It has been observed that the model developed in this study can capture the coupled dynamics between the rear suspension and the vibration isolation system. Results indicate that the nonlinear design of the vibration isolation system can be useful in enhancing ride comfort in the lower frequency range without an adverse impact on handling. Furthermore, it has been observed that the parameters associated with the nonlinear vibration isolation system can be tuned to enhance ride comfort while meeting the design requirements of spatial dynamics.