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This study focuses on experimental ageing tests with high temperatures carried out on prototype under ballast mats (UBMs) according to the procedure of the European standard EN 17282, which was introduced in late 2020. Most of the analysed UBM samples are based on recycled elastomeric materials, such as styrene-butadiene rubber (SBR) granules and fibres from end-of-life car tyres and rebond polyurethane waste from polyurethane product manufacturing plants. Additionally, two variations of the mat based on mineral wool are analysed. Significant differences in the values of static and dynamic characteristics measured before and after the ageing tests are demonstrated, and permanent deformations of the recycled polyurethane-based mats are shown. Moreover, it is proved that the elastomeric mats based on recycled rubber materials (SBR granules and fibres) have high durability and are an effective solution in terms of protection against vibration and structure-borne noise from railway traffic. In addition, the authors propose criteria for assessing the results of the ageing test with high temperatures of UBMs tested according to the procedure of EN 17282. [ABSTRACT FROM AUTHOR]

Due to the military operations conducted by the opponent during and after the 2020 Artsakh war, as well as potential future risks and threats, the Republic of Armenia faces the challenge of ensuring the secure livelihoods of border settlements and implementing programs aimed at territorial development. Therefore, raising the issues regarding the resistance of these settlements to possible military operations is of strategic importance and demands immediate attention. The research examines normative and technical documents adopted from both international and local experiences to mitigate the impact of military attacks. It delves into the potential for reducing casualties and material damage by organizing the spatial environment of settlements. Furthermore, it emphasizes the necessity of defining new terminology and formulating key assessment criteria. The proposed solutions can be the basis for proposing a new scientific theory in architecture and contributing to the development of new resistance solutions in architecture along with military technologies. [ABSTRACT FROM AUTHOR]

Seismic isolation technology makes buildings more capable of withstanding earthquakes, protecting them from major damages or collapse. The same methods of analyses are not suitable for all types of buildings. The isolation system used Armenia, unlike foreign countries ones, cannot take any tension forces since the system doesn't have structural connections to superstructure and substructure of a building. The consequence of this fact can be the occurrence of additional stresses after the redistribution of axial forces in rubber base isolations in high-rise buildings during a seismic action. The stress-strain state analyses of rubber base seismic isolation systems in reinforced concrete dual frame-wall buildings with application of a finite element method carried out in the manuscript. An increase of the stresses during seismic action is discussed and investigated using both Fast-nonlinear time history analysis (FNTHA) and Direct-integration nonlinear time-history analysis (DINTHA). Analysis of the results of the study shows that the axial forces after their redistribution during horizontal earthquake loads in most seismic isolators of high-rise building do not exceed 8%, but for some isolators this difference varies within the range of 12-18% . Taking into account the vertical component, the difference does not exceed 20%, with the exception of three isolators, where it can reach up to 23% . An average increase of the compressive axial forces in the seismic isolation bearing systems of the tall building as a result of redistribution can be taken about 10% . In this case, the displacements and the axial forces of the seismic isolators during analysis of their bearing capacity must be considered simultaneously, but not separately from each other. [ABSTRACT FROM AUTHOR]

Nowadays, an extensive number of studies related to the performance of base isolation systems implemented in regular reinforced concrete structures subjected to various types of earthquakes can be found in the literature. On the other hand, investigations regarding the irregular base-isolated reinforced concrete structures' performance when subjected to pulse-like earthquakes are very scarce. The severity of pulse-like earthquakes emerges from their ability to destabilize the base-isolated structure by remarkably increasing the displacement demands. Thus, this study is intended to investigate the effects of pulse-like earthquake characteristics on the behavior of low-rise irregular base-isolated reinforced concrete structures. Within the study scope, investigations related to the impact of the pulse-like earthquake characteristics, irregularity type, and isolator properties will be conducted. To do so, different values of damping ratios of the base isolation system were selected to investigate the efficiency of the lead rubber-bearing isolator. In general, the outcomes of the study have shown the significance of vertical irregularity on the performance of base-isolated structures and the considerable effect of pulse-like ground motions on the buildings' behavior. [ABSTRACT FROM AUTHOR]

Two types of elastomeric vibration isolators used for equipment vibration isolation in aerospace vehicles are considered for the present study. These isolators are constructed using elastomers mounted in steel encasings. These isolators are initially deformed statically and dynamic loads are applied on the deformed configuration. To capture the static deformation, equivalent static load corresponding to its load rating and specified displacements are created. Static deformation is computed using Finite Element methods with four node axi-symmetric element which include the geometric non-linear effect for steel and with standard Yeoh hyper-elastic material model for elastomers (Muhammed and Zu, 2012) [1]. Yeoh material constants are derived from uni-axial tension test data of the elastomer specimen. These isolators are subjected to harmonic and random excitations in the pre-deformed state. For numerical analysis, elastomeric constants at dynamic conditions are obtained as complex function of frequency using Dynamic Mechanical Analyzer (DMA) for a range of frequencies. The standard material model of Yeoh is modified incorporating frequency dependant material characteristics and damping in the range of frequencies of interest. A multiplicative non-separable variables law is derived for Yeoh material model to include the effect of static pre-stress, based on the methodology given in literature (Nashif et al., 1985; Beda et al., 2014) [2,3]. The modifications of Yeoh model suitable for frequency domain analysis is the novelty in the present study. In the analysis, while dynamic loads are applied, the configuration is updated considering initial static loading. The frequency response of the isolators is computed using material properties evaluated at progressive dynamic strains until a match in natural frequency is observed. Appropriate damping corrections are then incorporated to match the test observed transmissibility. Then updated material properties are used to compute the random response which showed good agreement with results of experiments, validating the approach taken for the development of this model. [ABSTRACT FROM AUTHOR]

The current work investigates the relationship between the shape of an isolator of a concentric rotary piston compressor and the secondary peak pressure developed during each operating cycle. This peak pressure is developed when the piston passes through the isolator cavity, and it is negative for compressor efficiency. The aim of this paper is to identify the isolator cavity shape that minimizes this secondary peak to improve compressor efficiency. This study covers five different cavities that may be used in such compressors. Contrary to our expectations, the conclusion is that the best geometry is the one that can be manufactured with CNC machining. The geometry that can be manufactured with 3D printing also produces a significantly lower secondary peak pressure, but it is not cost-efficient. Another limitation of the 3D printing design is the thin walls that this cavity creates. Very thin walls may cause significant deformation during the compression cycle. The conclusion is that there is a CNC machining design that is cost-efficient and allows for higher compressor performance. [ABSTRACT FROM AUTHOR]

Magneto-rheological (MR) materials can respond reversibly and quickly under the effect of an external magnetic field. MR materials contain micron-sized iron particles. These iron particles are typically dispersed in an elastomer or a liquid. These materials due to their properties constitute a kind of smart material in terms of engineering material. Such materials are used as isolators in various engineering applications, structures, and sound control subsystems. This study aimed to determine the mechanical properties for shear behavior of MR materials for under harmonic loading. Parameters such as matrix materials with different hardness values, powder types, magnetic field, frequency, and deformation were studied. The parameters related to the MR material itself were analyzed with the obtained data. The present study reveals that considering the sensitivity to magnetic field parameter, composite materials having the most suitable properties were produced with Shore 2 hardness value and SQ magnetic powder. It had been observed on increase about 200% at the rate of Shore A10 and A2 as a result of comparing the hardness scale. Also according to the powder rate while there was an increase on worth effect of relative MR, it is seen that the biggest increase had been in SQ powder with 199% worth. When looked some studies in literature, about comparing different hardness values such as matrix materials powder types etc. there aren't any studies. The state of magnetic field thinks that features such as MR effect, Storage, and Loss modulus haven't been examined yet. [ABSTRACT FROM AUTHOR]

The interaction of dual-micro-cavity defect modes in a one-dimensional photonic crystal consisting of graphene layers is studied by using the transfer matrix method. The numerical relation of resonances and splitting condition of them are determined in this structure. Results show that for specific repetition numbers of surrounding and middle cells of the structure, a defect mode is split into two completely separated modes. Also, threshold states for merging the defect modes are determined for different amounts of these parameters. In addition, the transmission coefficients and the Faraday rotation angles of these states are calculated and compared with each other. By calculation of light intensity distribution inside the structure at resonance wavelengths, we present consistent qualitative interpretation of the analytical results. The information achieved by this research can be useful to fabricate a variety of graphene-based photonic systems and magneto-optical integrated devices such as miniaturized isolators and circulators. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this investigation is the development of a passive vibration isolator with high-static stiffness to bear static load while limiting the static displacement and providing lower-even-zero dynamic stiffness required to reduce the basic natural frequency resulting in an increased frequency range over which attenuation can be achieved. Methods: A passive vibration isolator integrated a dynamic vibration absorber with a negative stiffness spring is proposed. The dynamic behavior of the new isolator supporting a lumped mass is investigated using force and displacement transmissibility equations. The force and displacement transmissibility equations are derived by modelling the dynamic system as a two-degree-of-freedom system rather than a single-degree-of freedom system as that of a traditional passive vibration isolator. A unique constraint on the negative stiffness ratio α for the isolator's stable operation is developed. The design of such an isolator is further demonstrated with an example. Results: Extensive numerical simulation and parameter studies on the isolator were performed. The attractive dynamic characteristics of the isolator were revealed. It is a passive linear isolator, without any nonlinear elements, spring or damper. However, it can bear a large static load and, at the same time, achieve a greatly increased vibration isolation region. Conclusion: The suggested passive vibration isolator can provide high-static stiffness to meet the requirement on load bearing while excellent dynamic performance, including increased vibration isolation region and decreased transmissibility, can be achieved. All these make the isolator attractive for engineering application. [ABSTRACT FROM AUTHOR]

Elastomeric seismic isolation is a technique diffused in civil engineering to protect existing and new structures against earthquakes. It consists in introducing between the superstructure and the foundation several devices (called seismic isolators) having the property to carry vertical loads maintaining at the same time the shear modulus small, increasing considerably the natural period of the structure, where the spectral acceleration drops down (Habieb et al., 2020 and 2019a, 2019b, 2019c, 2019d, 2018). This study investigates the possibility of using recycled rubber in the form of reactivated EPDM (made by 2/3 of regenerated rubber and 1/3 of virgin rubber) for the production of low cost rubber isolators (Habieb et al., 2020). A Fiber Reinforced Elastomeric Isolator FREI prototype constituted by five EPDM pads and four GFRP laminas interposed between contiguous pads is cured in the lab at 130°C and the level of vulcanization is experimentally provided measuring Shore A hardness on several points. A 3D numerical model based on both finite differences and FEM is proposed to predict the degree of vulcanization of the FREI numerically. It is found that the crosslinking density obtained is suboptimal (but still acceptable for an engineering point of view) and that it is required to increase the vulcanization temperature to obtain a full and homogeneous curing. [ABSTRACT FROM AUTHOR]

This study is concerned with the problem of analysis and optimization of inerter-based systems. A main inerter system is generally composed of an inerter, a spring, and viscous damper. Series – parallel inerter system s and series inerter system s are two commonly used configurations of inerter-based system s. First , in this study , the H ∞ optimum parameters of inerter-based isolators are derived to minimize the compliance and mobility transfer function of a single-degree -of-freedom system under a harmonic ground acceleration excitation. Under the optimum tuning condition, it is shown that the proposed inerter-based isolators when compared with the traditional dynamic vibration absorber provide larger suppression of the peak value of the magnitude of compliance and mobility transfer function s of the primary system. For the studied cases, more than 40% and 45% improvement can be attained in terms of minimizing the compliance and mobility transfer function s , respectively, as compared with the traditional dynamic vibration absorber for the series – parallel inerter system and 15% and 11% improvement can be attained respectively , for the series inerter system. Finally, further comparison between the inerter-based isolators and traditional dynamic vibration absorber under white noise excitation also shows that the series – parallel inerter system and series inerter system s are superior to the traditional dynamic vibration absorber. The results of the studied systems show that m ore than 23% and 16% improvement are attained in terms of minimizing the compliance and mobility transfer function s respectively , as compared with the traditional dynamic vibration absorber for the series – parallel inerter system and 26% and 13% improvement can be attained respectively , for the series inerter system. The optimal parameters for different cases are obtained. It is shown that the optimal parameters obtained using the minimized mobility transfer function are smaller than those using the compliance transfer function at all mass ratios or inertance-to-mass ratio. The results of this study can provide theoretical basis for design of the optimal inerter-based isolators in engineering practice. [ABSTRACT FROM AUTHOR]

Most of the engineering vibrations are harmful, due to many unfavorable consequences caused by them, such as structural damage, poor working accuracy, etc., making it necessary to implement vibration isolation measures. Traditional linear vibration isolation methods have significant deficiencies regarding isolating low-frequency vibrations, in which the stiffness of the isolation system becomes a dominant factor. The quasi-zero-stiffness (QZS) vibration isolation technology, developed in recent decades, can greatly reduce the dynamic stiffness without reducing the static stiffness and thus extend the vibration isolation frequency band to low frequency region. A variety of approaches for constructing QZS isolators have been proposed based on geometric nonlinearity, magnetic nonlinearity, deformable components and so on. With higher demands and more complex operating conditions, many improvement strategies have been proposed to further enhance the overall performance of QZS isolators from various aspects. To date, a small portion of theoretical achievements in QZS vibration isolation have been applied in engineering fields, showing great advantages over linear vibration isolation methods. In these contexts, a comprehensive review of the QZS vibration isolation technology is essential. This paper is devoted to summarize the main research progress of QZS vibration isolation in terms of designs, improvement strategies and applications, to provide a general overview of the QZS vibration isolation technology for researchers in related fields. • Various approaches for constructing QZS isolators are elucidated. • Improvement strategies are expounded to further enhance the QZS isolators. • Some application examples of QZS isolators in engineering are presented. • Future prospects for QZS vibration isolation are provided. [ABSTRACT FROM AUTHOR]

We perform a theoretical study of the nonreciprocal reflection of high-frequency microwave radiation from ferromagnetic films with thin overlayers. Reflection from metallic ferromagnetic films is always near unity and shows no nonreciprocity. In contrast, reflection from a structure which has a dielectric overlayer on top of a film composed of insulated ferromagnetic nanoparticles or nanostructures can show significant nonreciprocity in the 75-80 GHz frequency range, a very high value. This can be important for devices such as isolators or circulators. [ABSTRACT FROM AUTHOR]

(Dy0.7Y0.25La0.05)2O3 magneto-optical transparent ceramics were successfully fabricated by pressureless sintering in reductive H2 atmosphere (PLSH). The raw powder of (Dy0.7Y0.25La0.05)2O3 was synthesized by a modified self-propagating high-temperature synthesis (SHS) and sintered to transparent ceramics at 1400-1600 °C in a flowing H2 atmosphere, showing good sinterability of the as-synthesized raw powder. The magneto-optical Verdet constant of (Dy0.7Y0.25La0.05)2O3 transparent ceramics was measured to be -191.57 rad/(T-m) at a wavelength of 632.8 nm. In this magneto-optical material of (Dy0.7Y0.25La0.05)2O3, relative cheaper Dy and Y were used to replace Tb, and the low cost and good magneto-optical property showed the advantage of application on Faraday isolators (FIs) and Faraday rotators (FRs). [ABSTRACT FROM AUTHOR]

A X‐band aperture‐coupled patch antenna based on backed substrate integrated cavity (SIC) and pins‐loaded cross slot with dual linear polarization and high isolation is investigated. Loaded pins are applied to cross aperture to reduce the mutual coupling between the slots. SIC is used to reduce the coupling caused by parallel plate mode. Moreover, one‐cross‐point structure of feed networks is used to further improve the isolation. A prototype of the dual‐polarized antenna is fabricated and measured. The measured results show that the dual‐polarized antenna exhibits impedance bandwidths better than 30% (voltage standing wave ratio ≤2), cross polarizations better than −27 dB. And the isolation between the two ports is above 51 dB. To the best knowledge of the authors, this is the highest isolation yet achieved for a patch antenna with wide bandwidth. [ABSTRACT FROM AUTHOR]

When an impact drive mechanism (IDM) is subjected to a heavy load, the large inertia of that load will seriously decrease the moving efficiency of the IDM. To solve this problem, a method of dynamic mass isolation is introduced in this article. The influence of load inertia is decreased to a minute value by adopting a light slider and using a spring between the load and the IDM. Thus, the moving efficiency can be increased. Kinematic models have been established and calculated by MATLAB/Simulink. Two prototypes have been fabricated and used to conduct a series of experiments. With a load of 1.8 g, the prototype with dynamic mass isolation presents a moving efficiency of 50.6%, whereas the other prototype without isolation presents a moving efficiency of only 11.9%. As a result, the average step size of the former is approximately four times larger than that of the latter. Moreover, the prototype with dynamic mass isolation can hold almost the same average step size with a wide range of load mass. The proposed method is low cost and may have practical significance for application in any known IDM-based actuating system to improve the performance. [ABSTRACT FROM AUTHOR]

This paper investigates a type of linear vibration isolator which incorporates two passive devices, negative stiffness elements and an inerter, into the conventional isolator (massstiffnessdamper). Two configurations of the passive devices are considered, respectively: (1) the direct parallel connection of the inerter and the negative stiffness element; (2) the series connection of the inerter with the viscous damper, which, together, is then connected with the negative stiffness element in parallel. Numerical evaluations are presented for the isolators subject to base harmonic and shock excitation, in terms of the natural frequency, the displacement transmissibility and shock isolation performance. Compared with other corresponding linear isolators, it is found that in the majority of the excitation situations, the presented isolator with the second configuration has a better performance for some isolator parameter values, that is, the inertance-to-mass ratio, the ratio of negative to positive stiffness and the damping coefficient ratio of the two dampers. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomer is a new intelligent material, which shows a promising application prospect in the intelligent control area. In the molding of magnetorheological elastomer, vulcanization under magnetic field condition is the critical step. However, the traditionally used vulcanization apparatus cannot be applied in the preparation of magnetorheological elastomer directly for the unavailable magnetic field, uneven pressure, and serious heat dissipation. An improved vulcanization apparatus with magnetic field generator, support device, and temperature control device was designed. To ensure the rationality of the designs, magnetic circuit simulation, thermal simulation, and stiffness consistency test were conducted. Experimental tests showed that the vulcanization apparatus we designed applied well in the preparation of magnetorheological elastomers and magnetorheological elastomer isolator. [ABSTRACT FROM AUTHOR]

The selection of cold-tolerant forms was carried out during seed germination at a temperature of 9°C. Root material was grown in flowerpots, seeds were obtained by self-pollination in individual isolators. After repeated selections, the combining ability of the most valuable forms was studied as the parent components of the cross when creating new hybrids. The offspring of genotypes selected with the help of a cold background exceeded the control on the basis of germination and length of the seedling. The effectiveness of such studies is shown by the example of new hybrids Azimut, Kuban MS-95, and Uspekh. [ABSTRACT FROM AUTHOR]

Dynamic substructuring (DS) is a research field that has gained a great deal of attention in both science and industry. The aim of DS techniques is to provide engineers in structural vibrations and sound practical solutions for analyzing the dynamic behavior of complex systems. This paper addresses the singularity problem that occurs when flexible joints are implemented as substructures into the Lagrange Multiplier Frequency-Based Substructuring (LM-FBS) coupling process. For illustration, we use rubber bushings from an automotive application. Considering the rubber isolators to exhibit hysteretic damping, we assume that only the property of the dynamic stiffness of material is given. To avoid singularity appearing in the admittance when inverting the impedance of a massless joint, we compare three different approaches to include rubber bushings in the framework of LM-FBS. One method consists in including the dynamic stiffness of material directly in the space of the interface constraints and add it to the assembled interface flexibility of the LM-FBS equation. This corresponds to a relaxation of the interface compatibility condition. In the second method, the rubber bushing is treated as a substructure by adding small masses to the equation of the joint. As a result, we obtain a nonsingular total dynamic stiffness matrix that can be included in the coupling process. The third method describes a novel extension of the LM-FBS approach, based on a solution for singular problems. If the applied forces are self-equilibrated with respect to the rigid body modes, a solution for the singular dynamic stiffness matrix exists. The methods are outlined, both mathematically and conceptually, based on a notation commonly used in LM-FBS. They facilitate the integration of connecting elements together with experimental or numerical determined system dynamics of substructures in order to predict the assembled system behavior. [ABSTRACT FROM AUTHOR]

This study is concerned with structural vibration reduction using a four-parameter isolator designed as a scissor-like structure, which can induce geometric nonlinearity during the deformation process. The displacement transmissibility of the isolator including the geometric nonlinearity under base excitations is thoroughly investigated. First, the dynamic model of the four-parameter isolator is presented. Then, by utilizing the harmonic balanced method (HBM), the steady-state solutions of the inertia mass and auxiliary spring of the proposed isolator are derived. The analytical solutions are validated by comparing with those obtained by the direct numerical integrating method. Besides, the natural frequency of the nonlinear isolation system is presented and investigated. Moreover, the isolation performance of the four-parameter isolator is assessed in terms of the relative and absolute displacement transmissibilities, and compared with that of the linear Zener model, by which the advantages of the present isolator have been clearly revealed. The effects of various design parameters on the displacement transmissibility of the isolator are also analyzed. Finally, a further comparison between the analytical and experimental results under base excitation also shows that the mechanical model used for the four-parameter isolator is accuracy enough. The present results may provide a useful theoretical basis for the design of the four-parameter isolator in engineering practice. [ABSTRACT FROM AUTHOR]

A staircase provides the main escape way from a building in an emergency. Unfortunately, it may suffer severe damages or even collapse during an earthquake. For improving the seismic performance of staircases, this paper proposes an innovative staircase isolator with the features of lightweight, costeffective and ease of construction and replacement, which is formed by suitable engineering plastic shims between rubber layers. A connection construction scheme is also proposed for the isolated staircase. Systematic performance tests have been carried out to characterize the isolator in terms of mechanic behavior and ultimate states. The test results show that mechanical properties of the proposed staircase isolator are excellent and suitable for staircase in building structure. In order to investigate the influence of staircase on building structural responses, time history analyses of a typical building structure without staircase (WS), with fixed staircase (FS) and with isolated staircase (IS) are conducted and compared within the environment of SAP2000. Results show that staircase isolation can effectively eliminate the diagonal bracing effect of staircase slab and make structural components uniformly stressed. When the novel isolator is employed for staircase in a building structure, there is no vulnerable position in staircase and the performance of staircase in building structure can be greatly enhanced. [ABSTRACT FROM AUTHOR]

High precision measurements in various applications rely on active seismic isolation to decouple the experiment from seismic motion; therefore, closed feed-back control techniques such as sensor blending and sensor correction are commonly implemented. This paper reviews the active isolation techniques of the Albert Einstein Institute seismic attenuation system (AEI-SAS). Two approaches to improve the well known techniques are presented. First, the influence of the sensor basis for the signal-to-noise ratio in the chosen coordinate system is calculated and second, a procedural optimization of blending filters to minimize the optical table velocity is performed. Active isolation techniques are adapted to the mechanical properties and the available sensors and actuators of the AEI-SAS. The performance of the final isolation is presented and limitations to the isolation are analyzed in comparison to a noise model. The optical table motion reaches approximately at 1 Hz, reducing the ground motion by a factor of approximately 100. [ABSTRACT FROM AUTHOR]

The absolute gravimeter plays an important role in metrology, geophysics, and geological exploration. Seismic and environmental vibration has been one of the most serious factors limiting its performance. Consequently, an ultralow-frequency vertical vibration isolator is required to significantly improve its measurement precision. A novel active vertical vibration isolator employing geometric antispring (GAS) structure is proposed in this paper. The payload is supported by a GAS structure fixed on an inner frame, and the inner frame is hung by coil springs from the base. The relative movement of the payload with respect to the inner frame is detected, and the inner frame is driven by a voice coil actuator controlled by a feedback circuit to track the payload’s motion. The new isolator has a compact size, and it can be used for different load ranges by tuning the GAS structure. The practical closed-loop system has a resonant period of 19.2 s, compared with the period of 0.74 s in an open-loop system. Experiments showed that the new isolator has great performance in a homemade T-1 absolute gravimeter, reducing the measurement deviation by a factor of 32. It is expected to be used in both free-falling and atomic-interference absolute gravimeters. Future improvements may include optimizing the mechanical structure and integrating a temperature control subsystem. [ABSTRACT FROM AUTHOR]

This paper proposes a low-loss and high-isolation transformer (TF)-based mm-wave single-pole double-throw (SPDT) switch. The center-tapped technique is employed at the secondary coil of TF to improve isolation performance. The TF is implemented with the metals in redistribution layers (RDLs) in integrated fan-out (InFO) wafer level packaging technology to obtain low insertion loss (IL) and small chip size as the TF usually dominates the area of SPDT. The control device of the SPDT is realized in 40 nm bulk CMOS process. The simulated result shows the proposed SPDT achieves a minimum IL of 1.34 dB and the IL is less than 2.2 dB at 24–31 GHz. The isolations are better than 27 dB between two double-throw ports and better than 20 dB between single-pole and double-throw ports, respectively. The proposed SPDT has a compact silicon size of 220 μ m × 1 4 0 μ m (with PADs) and its return losses are better than − 9 dB at 24–31 GHz and. This work explores a new chip-package co-design method for the SPDT and may have some guidance for the co-design of SPDT and antenna in package (AiP). [ABSTRACT FROM AUTHOR]

Summary: An innovative subsystem with the incorporation of eddy current (EC) damping and magnetic negative stiffness spring (MNSS) is proposed to develop feasible strategies for performance improvement of existing base isolation techniques. The concept of integrating the eddy current damping mechanism and the nonlinear negative stiffness spring is firstly introduced for better energy transition behavior under earthquake excitations. The analytical expressions of the force characteristics of the EC and the MNSS components are presented accordingly, and a parametric study is conducted to evaluate the inherent properties of the integrated magnetic subsystem. To demonstrate the advantages of the EC–MNSS subsystem, an illustrative example of a two‐DOF model simulating both the superstructure and the isolation layer is numerically investigated by adopting two representative isolators and the proposed subsystem. The EC–MNSS subsystem is illustrated to significantly and simultaneously improve the isolation performances in terms of base drift and structural acceleration. The energy exchange and dissipation behavior are further revealed by employing time history analysis and energy‐displacement‐velocity plots. Furthermore, the proposed EC–MNSS subsystem is implemented in a benchmark isolation problem adopting an eight‐story frame structure subjected to bidirectional earthquake excitations. The simulation results indicate the superior and the comparable performances of the integrated isolation system as compared to those of the passive and the control‐augmented isolations, respectively. [ABSTRACT FROM AUTHOR]

A novel four-port circulator is presented which uses an inline ferromagnetic element to allow for transmission or reflection depending on the sense of the incident circularly polarized wave. This configuration has been shown to reduce the dependency on ferrite anisotropy and support higher power, low rf loss, operation. An analytic analysis of this device is presented alongside corroborating cold test data of the first prototype. High-power operation was performed at 2.856 GHz, with input power levels up to 8 MW for $3.5~\mu \text{s}$ in a pressurized nitrogen environment. The results from this research not only demonstrate ability to eliminate the use of greenhouse insulators, such as SF6, but also provide conceptual groundwork for a new class of ultrahigh power (50 MW+) nonreciprocal networks including circulators, isolators, phase shifters, and rf switches. [ABSTRACT FROM AUTHOR]

Tuned Mass Damper (TMD) with magneto-rheological elastomer isolators (MRE-TMD) is a novel control device for suppressing structural vibration caused by earthquakes. It is a nonlinear hybrid vibration absorber and the stiffness & damping can be controlled by changing the current of isolators' coil. Using MRE-TMD as an adaptive frequency TMD to mitigate vibration and treating it as only a passive damper is the focus of most nowadays researches. In this paper, semi-active control theory is introduced to the MRE-TMD-structure system which means that the control force can be obtained through variable stiffness & damping technology, and MRE-TMD is a semi-active damper instead of a passive one. A control system sketch, as well as principles and control strategies of a semi-active MRE-TMD-structure system for vibration control is designed. An improved limited sliding (ILSL) algorithm based on linear quadratic optimal theory is also introduced. Numeric simulations of a five-story benchmark building model equipped with semi-active MRE-TMD subjected to several benchmark earthquake records are conducted to investigate the control performance of the proposed semi-active MRE-TMD. Control force characteristics of the structural MRE-TMD systems are also evaluated. The results indicate that semi-active MRE-TMD can provide control force to the system and it shows superior ability to suppress the structural vibrations of comparing to the passive MRE-TMD. [ABSTRACT FROM AUTHOR]

A polarization rotator based on substrate integrated waveguide (SIW) is proposed in this article. The rotator is designed as a dual-band, single-layer, frequency-selective surface (FSS) that transmits a wave rotated of 90° with respect to the incident one in one of the two bands maintaining unchanged the polarization in the other one. Other than the design and characterization of the rotator, its application to a linear-to-circular dual-band polarizer is also investigated. To this purpose, the rotator is coupled to a conventional meander line polarizer generating orthogonal circular polarizations (CP) in the two bands. This configuration is useful in SatCom applications where the required high isolation between TX and RX channels is obtained assigning orthogonal polarizations to the two bands. As a design example, a prototype is designed and experimentally validated in the SatCom K-/Ka-bands. Measured performance shows an isolation between the TX and RX channels of more than 35 dB and insertion losses which do not exceed 1.5 dB in the two operating bands. [ABSTRACT FROM AUTHOR]

The 2008 Wenchuan earthquake brought numerous issues to the attention of researchers of seismic mitigation in Chinese museums. After the Wenchuan earthquake, the structural design team of Chengdu Museum conducted a series of research projects on seismic mitigation and subway vibration control design of buildings. These projects included the following topics: optimization of design, numerical simulation of seismic performance, analysis of key technologies for the base isolation structure, in-depth studies on structural vibrations caused by the nearby subway, and proposals for reducing structural vibrations. In 2015, after the superstructure of Chengdu Museum was completed, conservators evaluated the safety of permanent exhibitions under earthquake conditions. Seismic protection devices were installed on the showcases according to the preventive conservation requirements for museum collections. Reinforced measures were used for museum collections according to the methods suggested in the document 'Specification for seismic protection of museum collection' (WW/T 0069-2015). The conservators also built a systematic platform for earthquake monitoring for museum collections. Preventive conservation studies on seismic protection and subway vibration control in Chengdu Museum are summarized and forecasted. [ABSTRACT FROM AUTHOR]

This article deals with structural vibration attenuation and control using periodic materials for isolation of structures. An innovative approach to achieve wider low-frequency attenuation zones using a combination of different one-dimensional periodic units has been explored to provide close to a vibration-free environment for civil engineering structures subjected to seismic and other excitations. The wave attenuation regions for the base isolation system made of periodic materials have been derived from the theory of phononic materials and investigated using parametric studies and finite element modelling. The concept of combined periodicity is implemented on bridges to achieve wider attenuation zone and higher response reduction. A novel concept of using a hollow-shell periodic isolation system on bridges has been presented to minimize the effect of seismic waves on these structures. A substantial reduction in the seismic response of a bridge model has been observed over the entire frequency domain with the introduction of the proposed isolation systems. The proposed hollow-shell periodic isolation system reduces the seismic response of structures with efficient material utilization as compared to the typical solid-periodic isolation systems. The proposed isolation systems thus open up new directions for research and potential implementation of periodic materials for seismic response reduction and earthquake-resistant design of structures. [ABSTRACT FROM AUTHOR]

An active vibration isolation system is retrofitted to a diesel generator set in a tugboat to determine the effectiveness of such a system in a realistic practical environment. The system consists of six bespoke inertial actuators chosen to make minimal modifications to the machinery arrangement, and a DSP-based controller. Six accelerometers are collocated with the actuators on the top of six isolators to act as error sensors, and six accelerometers are placed below the isolators to give a measure of the global vibration of the ships structure below the generator set. A hydrophone is also placed in the water to give an indication of the underwater noise due to the generator. The control strategy employed is six-input and six-output decentralized adaptive feedforward control with the reference signal being derived from the signal from an optical tachometer on shaft between the engine and the generator. To suppress the vibration at all the dominant forcing frequencies, an electrical circuit generated the half engine orders required from the measured reference signal. The experimental results show that the combination of the active control system and the passive isolators is effective in reducing the global vibration and the acoustic pressure at the hydrophone position. [ABSTRACT FROM AUTHOR]

Magneto-rheological mount is one of the most effective vibration isolation devices for the vibration isolation system of vehicle powertrain. In this article, a flow type of magneto-rheological mount was proposed to control the vibration and the torque excitation of the engine when vehicle was in start/stop mode. A mathematical model for the flow type of magneto-rheological mount was formulated with consideration of the influence of current on magneto-rheological fluid viscosity and the relationship between liquid resistance effect and flow rate in damping gap. Then, a co-simulation optimal platform was developed by the Isight and the ANSYS, and the non-dominated sorting genetic algorithm II was used to optimize magnetic circuit. Subsequently, two prototypes of magneto-rheological mounts were manufactured according to the initial design and the optimal design model, and the dynamic performance test of magneto-rheological mount monomer and the vibration isolation performance test of the whole vehicle under start/stop mode were carried out, respectively. The experimental results showed that the controllability and the vibration isolation performance of the optimal design magneto-rheological mount were significantly improved compared with the initial design. [ABSTRACT FROM AUTHOR]

This work studies a haptotaxis system proposed as a model for oncolytic virotherapy, accounting for interaction between uninfected cancer cells, infected cancer cells, extracellular matrix (ECM) and oncolytic virus. In addition to random movement, both uninfected and infected tumor cells migrate haptotactically toward higher ECM densities; moreover, besides degrading the non-diffusible ECM upon contact the two cancer cell populations are subject to an infection-induced transition mechanism driven by virus particles which are released by infected cancer cells, and which assault the uninfected part of the tumor. The main results assert global classical solvability in an associated initial-boundary value problem posed in one- or two-dimensional domains with any given suitably regular initial data. This is achieved by discovering a quasi-Lyapunov functional structure that allows to appropriately cope with the presence of nonlinear zero-order interaction terms which apparently form the most significant additional mathematical challenge of the considered system in comparison to previously studied haptotaxis models. [ABSTRACT FROM AUTHOR]

Summary: Due to their low inherent damping and high lateral flexibility, stay cables are prone to large amplitude vibrations governed by either a single or multiple cable modes. Among the practical measures, the installation of transverse passive dampers near the cable‐deck anchorage is a popular choice. Compared to conventional positive stiffness and zero stiffness dampers, negative stiffness damper (NSD) manifests superior performance in mitigating cable vibrations, especially in the case of long cables. In this study, a novel design approach is proposed to optimize NSD for multimode cable vibration control. Two design scenarios are considered. In the former, the damper size is optimized for a predetermined negative damper stiffness; whereas in the latter, the size and negative stiffness of the NSD are both optimized to achieve a required damping ratio for the dominant modes. The applicability of the proposed NSD optimum design approach is validated using 15 sample real stay cables. A numerical example is presented, of which a NSD is designed based on the proposed approach to optimize wind‐induced multimode vibration control of a 460‐m stay cable, and the performance is compared with that of a linear‐quadratic regulator (LQR) control. Results show that the selected NSD can effectively suppress the dominant modes and has a controlling effect comparable with an active control using LQR. In addition, it is found that when there exist more than two dominant modes in vibration, designing NSD for the lowest and the highest dominant modes would also adequately control the mid‐range modes. [ABSTRACT FROM AUTHOR]

This article investigates the possibility of using active control devices for the seismic protection of museum artifacts subjected to sliding and rocking. An actively base isolated system is compared to a passively base isolated one constituted by a spring-dashpot system that can represent a simplified modeling of both a base isolator or a flexible case-supporting system. Results show that active base isolation has superior performance than the passive one for the seismic protection of museum's artifacts. Moreover, due to their adaptability and robustness, active control devices can be adopted for different works of art in different site exposure conditions. [ABSTRACT FROM AUTHOR]

This paper presents a parametric study of the collapse performance of two-story residential buildings equipped with a simple spherical concave deformable rolling isolation system cast in high strength concrete. The collapse performance follows the procedures of FEMA P695 with direct evaluation of the spectral shape effects and accounts for uncertainties. The isolation system consists of isolators with fixed dimensional parameters that include a displacement restraint system and have a displacement capacity of 650 mm. The designs considered in the study have properties that are representative of highly ductile reinforced concrete two-story residential buildings consisting of moment frames and/or shear walls designed in Turkey for a lateral force under elastic conditions corresponding to a spectral acceleration of 1 g. This is representative of areas of the highest seismic hazard in Turkey except for areas controlled by near-fault conditions. The simplicity in the design of the structural system and of the isolation system intend to facilitate application of the system without sophisticated analysis. The seismic collapse performance evaluation demonstrates that residential buildings designed by this procedures and using this isolation system have acceptable collapse performance as stipulated in the ASCE/SEI 7-16 standard. [ABSTRACT FROM AUTHOR]

A ±45°, dual-polarized, high-isolation, 1 × 2 multiple-input, multiple-output (MIMO) antenna array for wideband microbase-station application is presented in this article. The proposed antenna element incorporates two perpendicular magnetic coupling feeding (MCF) networks and an H-shaped slot in the ground plane to improve the port isolation. Simulation results indicate that it has an isolation of more than 38 dB. To suppress the mutual coupling between antenna elements, a dual wall consisting of a novel metasurface structure is introduced. When spatial-wave incidents occur, the isolation wall can restrain the electromagneticwave propagation. The electromagnetic waves produce resonance on the wall surface, which scatters some of the resonance, while the rest is transmitted to the ground and weakened by the decoupling structure between two elements. The metasurface walls, which are inserted vertically between the antenna elements, improve the isolation by roughly 5.9 dB within the 2.5-2.7-GHz frequency band and reach a maximum of -22.8 dB at approximately 2.6 GHz. The proposed antenna has been fabricated, and the experimental results are near the simulation responses. [ABSTRACT FROM AUTHOR]

The electronic control box (ECB) is a key and precise component of a roadheader. The vibration of the ECB is an increasingly prominent issue as the machine capacity grows. In order to promote the isolation effect of the ECB, a whole-body vibration model considering the cutting effect is derived, based upon which the stiffnessdamping matching strategy for the ECB isolator is acquired. For engineering application, the tubular constrained damping isolator (TCDI) is developed based on the constrained damping theory and the matching strategy. The theoretical results show that the isolation effect of the ECB isolator strengthens as the stiffness coefficients decline and the damping coefficients increase. The configurations with larger rear stiffness coefficients and larger front damping coefficients could lead to a better vibration control effect. The experiment results indicate that the TCDI exhibits a greater capability of isolating the impact excitation than the traditional E-type isolator, thus verifying the whole-body vibration model for the roadheader and the matching strategy for the ECB isolator. This research can provide theoretical and practical references for the investigation of the dynamic behaviour of complex viscoelastic structures. [ABSTRACT FROM AUTHOR]

Seismic isolation devices were designed to protect three similar building structures, containing different objects with different fragilities, in a strong earthquake region. And a performance-based assessment framework, established by the PEER, was used to identify the seismic isolation efficiency of these devices. It optimized the ratios of spring part, viscous damping part and friction part in the seismic isolation devices, aiming at different functional buildings. Results show that a spatially concave friction distribution, combined with a weak spring, not only can reduce the structural acceleration response during earthquakes, but also decrease the structural residual displacement after earthquakes. Moreover, the spatially concave friction distribution can dissipate earthquake energy, but cannot hinder the recentering of structure like that of general uniform friction distributions. Consequently, the spatially concave friction distribution can partly or fully replace the viscous dampers, which are more expensive and short-lived. The reasonable combination of different components in the seismic isolation devices can satisfy different seismic requirements, aiming at different functional buildings. [ABSTRACT FROM AUTHOR]

This paper derived the expression to estimate the effective line moment mobility of a non-deterministic thin plate under moment excitation by a piezoelectric patch actuator. The piezoelectric patch actuator is assumed to generate purely line moments at each of its edges and regarded as a finite number of point moments acting on an infinite plate, which is achieved by integration method. The theoretical model is validated using MATLAB simulation and compared with experimental measurements on a randomized thin plate. The derived effective line moment mobility managed to closely estimate high-frequency response while cutting significant computational time and resource. Results from this study can be used in many applications ranging from vibration isolation where power transmission between the isolator with an area distribution and its host structure can be determined more accurately, and to design the optimal shunt circuit of a piezoelectric shunt damper for maximum power dissipation in order to reduce vibration of a non-deterministic thin plate. [ABSTRACT FROM AUTHOR]

In this article, a novel tunable isolation network and a novel ring-type reconfigurable single-to-balanced (SE-BAL), power-dividing (PD), and single-to-single-ended (SE) bandpass filter is proposed. The tunable isolation network consists of a simple $\pi $ -type resistive network with tunable varactors, while the proposed filter consists of three ring-type stepped impedance resonators (SIRs) connected by varactors in between. By simply combining the proposed tunable isolation network and the proposed ring-type reconfigurable filter, it can achieve multiple reconfigurable functions among SE-BAL filtering, PD filtering, and conventional SE filtering with fully matched three ports, arbitrary power-division ratios (PDRs), high output isolations, and excellent amplitude and phase balance, in addition to continuous frequency and independent bandwidth tuning. The proposed filter is demonstrated using the microstrip line technology. The measured results show that the SE-BAL, PD, and two SE filtering functions can continuously cover the frequency ranges of 1.03–1.61, 1.01–1.53, 1.03–1.56, and 1.06–1.48 GHz with −1-dB bandwidth tuning of 35–80, 50–140, 60–130, and 70–140 MHz, respectively; the 1-, 3-, and 5-dB PDRs have been demonstrated for both SE-BAL and PD filtering modes. The measured output return losses and isolation are better than 19 and 18 dB, respectively, for SE-BAL filtering mode and 20 and 16 dB, respectively, for PD filtering mode. Good agreement is obtained between the simulated and measured results. [ABSTRACT FROM AUTHOR]

This paper proposes a semi-active variable stiffness vibration isolation system based on electromagnetic spring for the low-frequency vibration isolation of mass-varying objects. It is achieved by four straight leaf springs in parallel to an electromagnetic spring system composed of a single electromagnet and a permanent magnet. The equivalent magnetic circuit method is used to compute electromagnetic force of the electromagnetic spring system, and mathematical model of the semi-active vibration isolation system is established according to Maxwell's equations. The nonlinear mathematical model is linearized at the equilibrium point by using the Taylor series expansion theorem to establish linear state-space representation of the system, and then using the traditional PID control method, a double closed-loop feedback control system of the inner current loop and outer location loop is designed. By controlling the current in the coil, the equivalent stiffness and electromagnetic force of the system are variable to achieve semi-active control. Furthermore, the control block diagram of the semi-active vibration isolation system is built based on Simulink software, then make a simulation analysis to the vibration isolation performance of the system and compare the effects of vibration isolation with inner current loop control and without inner current loop control, respectively. Finally, the experiments prove the correctness of the theory. It concludes that this semi-active vibration isolation system is a vibration isolation system with broad application prospects, which has fast current response, high vibration isolation efficiency, and an excellent vibration isolation effect for the low-frequency disturbance of mass-varying objects. [ABSTRACT FROM AUTHOR]

The use of friction pendulum devices has recently attracted the attention of both academic and professional engineers for the protection of structures in seismic areas. Although the effectiveness of these has been shown by the experimental testing carried out worldwide, many aspects still need to be investigated for further improvement and optimisation. A thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented in this paper. The proposed model is based on the observation that sliding may not take place as ideally as is indicated in the literature. On the contrary, the fulfilment of geometrical compatibility between the constitutive bodies (during an earthquake) suggests a very peculiar dynamic behaviour composed of a continuous alternation of sticking and slipping phases. The thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented. The process of fine-tuning of the selected modelling strategy (available to date) is also described. [ABSTRACT FROM AUTHOR]