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This paper reports on a new type of multi-functional bandpass filtering (BPF) architecture with center frequency tunability, switching-off, and isolator functionality. The proposed filter, isolator, and switch (FIS) combines frequency-tunable passive resonators with unilateral frequency-selective stages (UFSs) to achieve tunable, fully-directional, quasi-elliptic transfer functions. The UFS, consists of a transistor-based path and a tunable feedback network, enabling frequency-selective transmission in the forward direction, RF signal cancellation in the reverse direction, and reconfigurability in terms of center frequency and intrinsic switching-off. It is demonstrated that by cascading UFSs and tunable resonators, highly selective frequency-tunable FISs can be developed. The proposed FIS also offers a reconfigurable switch-off mode capability with high isolation that is obtained by adjusting transmission zeros and reconfiguring the UFSs. In this paper, two types of UFSs are analyzed using circuit schematic simulations and coupling routing diagram (CRD)-based synthesis. Scalability to high-order transfer functions is also demonstrated by CRD-synthesized examples, design examples and manufactured prototypes. For experimental validation, two tunable UFSs and four tunable FISs were manufactured and measured at the L band.

In scramjet，the isolator plays a crucial role as a transitional component between the combustor and the inlet. Within the isolator，complex flow phenomena such as shock wave/boundary layer interactions，flow separation，and shock trains are observed under the influence of high back-pressure from the combustor. In this study，the self-adaptive turbulence eddy simulation（SATES）is used to numerically study the shock train characteristics in a cylindrical isolator. The primary focus is to analyze the potential challenges faced when the isolator is coupled with the combustor，including the effects of constant or pulsating back-pressure at the isolator exit and wall temperature on the shock train characteristics within the isolator. The results indicate that an increase in the exit back-pressure of the isolator，a decrease in the frequency of pulsating back-pressure，and an elevation in wall temperature can all cause the shock train to move towards the inlet，leading to potential unstart risks. Therefore，in practical engineering applications，particular attention should be paid to the high back-pressure and low-frequency oscillations induced during the combustor combustion process，as well as the wall heat conduction effects，to prevent the shock train from being expelled from the isolator，which could result in the unstart of not only the isolator but also the entire engine.

Isolator tegangan tinggi memainkan peran penting dalam memastikan keamanan sistem listrik yang beroperasi pada tegangan tinggi. Isolator memiliki fungsi sebagai pemisah tegangan antara konduktor fase dan konduktor fase lainnya dan juga antara konduktor fase dengan ground. Dalam perancangan sistem tenaga listrik, basic insulation level (BIL) tidak dapat diabaikan. BIL merupakan batas operasional tegangan maksimum sebelum isolator mengalami flashover. Selain harus mampu menahan tegangan, isolator juga harus mampu menahan kondisi lingkungan, seperti suhu, kelembapan, dan polusi, yang dapat memengaruhi kinerja isolator. Pada penelitian ini, dilakukan pengujian untuk melihat kinerja isolator kaca bekas PLTU Adipala ketika dipengaruhi oleh kondisi lingkungan dan dibandingkan dengan nilai BIL. Pengujian dilakukan dengan empat skema, yaitu pengujian dalam kondisi baik, pengujian dengan kondisi basah, pengujian dengan kondisi diberikan polutan, dan pengujian dengan kondisi ketika isolator dengan polutan berada pada kondisi lembap. Berdasarkan pengujian, didapatkan hasil bahwa kondisi yang sangat memengaruhi kinerja isolator adalah kondisi basah dan juga kondisi berpolutan dan lembap. Pada kondisi isolator bersih yang terkena hujan, penurunan kinerja isolator sebesar 19% sampai 25%, sedangkan pada kondisi diberikan polutan dengan equivalent salt deposit density (ESDD) 0,113816 mg/cm2 dan non-soluble deposit density (NSDD) 1,309962 mg/cm2 serta berada pada kelembapan 90%, terjadi penurunan kinerja sebesar 41% hingga 53%. Penurunan yang sangat signifikan ini tentunya mengakibatkan kinerja isolator berada jauh di bawah standar BIL.

Abstract In this paper, we present a new type of isolator based on one-way surface magnetoplasmons (SMPs) at microwave frequencies, and it is the first time that an experimental prototype of isolator with wideband and ultra-high isolation is realized using SMP waveguide. The proposed model with gyromagnetic and dielectric layers is systematically analyzed to obtain the dispersion properties of all the possible modes, and a one-way SMP mode is found to have the unidirectional transmission property. In simulation and experiment with metallic waveguide loaded with yttrium–iron–garnet (YIG) ferrite, the scattering parameters and the field distributions agree well with the analysis and verify the one-way transmission property. The isolation is found to be as high as 80 dB and the typical value of insertion loss is 1 dB. Besides, the one-way transmission band can be controlled by changing the magnetic bias. From theoretical analysis and simulation, it is found that with a tiny value of 10 Oe of the magnetic bias, the relative bandwidth can be tuned to be greater than 50%. Compared with conventional isolators, this one-way SMP isolator has the advantages of ultra-high isolation, wide relative frequency band, and requires much smaller bias field, which has promising potential in non-reciprocal applications.

Many vibration isolators, such as passive vehicle mounting devices, have an inflexible stiffness. This article presents the development of a smart material vibration isolator based on magnetorheological elastomer (MRE), which has adjustable stiffness to minimize unwanted vibrations. The objective of this research is to first create a design for the vibration isolator, and then simulate a magnetic circuit. The Finite Element Method Magnetics (FEMM) software was employed to simulate the effectiveness of the electromagnetic circuit in generating a magnetic field through the vibration isolator by employing MRE samples. Pure iron was chosen as the material for the housing of the vibration isolator test rig. To attain an optimal magnetic field, an inventive design of the magnetic circuit, including examination of the wire type, size, and coil turn number, along with the housing material of the test rig, was performed. The study analyzed the performance of the MRE vibration isolator concerning different current inputs in the coil. The results indicate that the stiffness value of the MRE-based isolator system can be more effectively modified by increasing the current inputs. Therefore, a larger current input leads to a greater change in stiffness.

The interaction between light and the magnetization of a material is called the magneto–optical effect. It was used in magneto–optical recording such as MO disks and has been applied to optical isolators etc. with the development of optical communications. The magneto–optical properties of magnetic garnets and their applications are briefly reviewed in this article. In the first half, after a brief overview of the phenomenology of the magneto–optical effect, the effects of element substitution on properties such as Faraday rotation and optical absorbance of magnetic garnets are shown. In the second half, some interesting applications such as imaging technologies and other novel applications using the magneto–optical effect of magnetic garnets are also introduced.

This work presents a rigorous design and experimental validation of a non-reciprocal bandpass filter (NBPF) employing time-modulated resonators with progressive phase shift sinusoidal modulation signal to achieve low forward transmission insertion loss (IL) and ultrawide high reverse isolation bandwidth. Analytical design equations have been derived for numerical design of NBPF asl well as providing insights of nonreciprocal frequency response. Additionally, these proposed analytical spectral S-parameters offer the flexibility to design NBPFs with arbitrary termination port impedances. This work also demonstrates a systematic approach to find modulation parameters without relying on optimization methods. It has established empirical relationships between the modulation parameters and the filters specifications to achieve low forward transmission IL and reverse isolation exceeding 15 dB at entire frequency range. The accuracy of the proposed NBPF design has been confirmed by comparing with harmonic balance simulation results of microstrip line NBPF. For experimental validation, three prototypes of NBPF with different termination port impedances are designed, implemented, and manufactured. In experimental results, the frequency of NBPFs can be continously tuned from 1.62 GHz to 1.94 GHz (17.98 %) with maximum forward transmission IL (|S21|) of 5.40 dB and input/output return loss higher than 12 dB. For each frequency tuning state, the reverse isolation (|S12|) exceeds higher than 20 dB across the entire frequency range.

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.

For a further understanding on 3D shock train structure and correlation between 3D and 2D shock trains at Mach 1.5 and 3.0, the SST turbulence model based on Reynolds average algorithm was employed to simulate the 3D and 2D structures of the shock trains in the isolator respectively, of which the mesh sizes were 18 million and 200 thousand, respectively. First, when the full flow state of the nozzle was completely converged, the shock train structure was induced by a linearly increasing back pressure at the outlet. Then, the 3D shock train simulation results in xy-plane and zx-plane perspectives were analyzed. Finally, structures of the 3D shock train in different slices and structures of the 2D shock train were analyzed for comparison. It is found that the shock train at Mach 1.5 is symmetrical in xy-plane and zx-plane perspectives, which is highly similar to the 2D simulation results. However, the shock train at Mach 3.0 is symmetrical in the xy-plane perspective, while it is asymmetrical in the zx-plane perspective. The asymmetrical structure is highly similar to 2D simulation results. Therefore, there is a ″quasi-2D area″ in the 3D shock train. For the shock train at Mach 1.5, the structures in the areas including the central position and a certain range on both sides of the xy-plane and zx-plane perspectives can be approximated as 2D structures (The proportion of ″quasi-2D area″ is about 40%); for the shock train at Mach 3.0, the structures in the areas including the central position and a certain range on both sides of the symmetrical viewing angle can be approximated as 2D structures (The proportion of ″quasi-2D area″ is about 60%).

Understanding aeroelastic issues related to isolators is pivotal for the structural design and flow control of scramjets. However, research on fluid–structure interactions (FSIs) between thin-walled structures and the isolator flow remains limited. This study delves into the FSIs between thin-walled panels and the isolator flow, as characterized by an oblique shock train, by quantitatively analyzing 11 flow parameters assessing the structural response, separation zones, shock structures, flow symmetry, and performance. The results reveal that an FSI triggers panel flutter under oblique shock train conditions, with the panel shapes exhibiting a combination of first- and second-mode responses, peaking at 0.75 of the panel length. Compared to rigid wall conditions, isolators with a flexible panel at the bottom wall experience downstream movement of the separation zones and shock structures, reduced flow symmetry, and minor changes in performance. Transient fluctuations occur due to the panel flutter. Two flexible panels at the top and bottom walls have a comparatively lesser influence on the averaged parameters but exhibit more violent transient fluctuations. Furthermore, the FSI effects under oblique shock train conditions are contrasted with those under normal shock train conditions. The flutter response under normal shock train conditions is more pronounced, with a larger amplitude and higher frequency, driven by the heightened participation of the first-mode response. The effects of FSIs under normal shock train conditions on the averaged parameters are the opposite (with a larger influence) to those under oblique shock train conditions, with significantly more drastic transient fluctuations. Overall, this study sheds light on the complex and substantial influence of FSIs on the isolator flow, emphasizing the necessity of considering FSIs in future isolator design and development endeavors.

Arrester merupakan sebuah perangkat yang berfungsi untuk melindungi peralatan dari kegagalan dielektrik yang disebabkan oleh impuls petir, switching surge, ataupun lonjakan tegangan yang melebihi kemampuan dielektrik suatu peralatan. Pada sebagian besar arrester dipasang alat penghitung kerja arrester (event counter) yang berfungsi untuk menghitung frekuensi arrester telah bekerja. Di kondisi lingkungan lembap dan polusi tinggi, pada bagian isolator sangat mudah terjadi surface discharge. Surface discharge merupakan discharge yang terjadi pada suatu daerah yang berhubungan langsung dengan permukaan dielektrik yang memiliki medan listrik berlebih, sehingga memicu terjadinya discharge. Surface discharge yang berlangsung secara terus-menerus dapat mengakibatkan flashover. Flashover yang mengenai bagian dari event counter dapat membuat event counter mengalami error sehingga tidak menunjukkan angka yang benar. Di samping itu, kinerja event counter akan terganggu. Untuk itu, perlu dilakukan pengujian isolator arrester dengan tiga skema, yaitu isolator kondisi bersih, isolator kondisi lembap, serta isolator dengan kondisi lembap dan berpolutan. Pada pengujian ini, digunakan polutan dengan nilai equivalent salt deposit density (ESDD) sebesar 4,69 mg/cm2 dan nilai nonsoluble deposit density (NSDD) sebesar 1,8841 mg/cm2. Berdasarkan hasil pengujian, diketahui bahwa terjadi penurunan kemampuan isolasi arrester dalam menahan tegangan yang diakibatkan oleh kelembapan dan polutan. Kelembapan memberikan penurunan breakdown voltage (BDV) sebesar 5,8 kV setiap kenaikan kelembapan 5%, sedangkan polutan memberikan penurunan BDV sebesar 59 kV ketika isolator diberi polutan.

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.

In this contribution, we simulate, design, and experimentally demonstrate an integrated optical isolator based on spatiotemporal modulation in the thin-film lithium niobate on an insulator waveguide platform. We used two cascaded travelling wave phase modulators for spatiotemporal modulation and a racetrack resonator as a wavelength filter to suppress the sidebands of the reverse propagating light. This enabled us to achieve an isolation of 27 dB. The demonstrated suppression of the reverse propagating light makes such isolators suitable for the integration with III-V laser diodes and Erbium doped gain sections in the thin-film lithium niobate on the insulator waveguide platform.

This paper reports on the RF design and practical development of GaAs MMIC multi-functional RF isolators and quasi-circulators with embedded filtering functionality. They are based on cascaded arrays of non-reciprocal resonators (NRRs), passive resonators, and impedance inverters. A unique transistor-based architecture is used for the realization of the NRR that exhibits an one-pole type bandpass response in the forward direction and RF signal cancellation in the reversed one. By controlling the number and type of resonators within cascaded resonator arrays, different levels of gain, out-of-band selectivity and in-band isolation can be obtained. The operating principles of the multi-functional isolator/filtering and quasi-circulator/filtering concepts are presented through synthesized and linear circuit-simulated examples. Practical design aspects using a commercially available GaAs MMIC process are also discussed. For proof-of-concept demonstration purposes, four prototypes were designed and experimentally validated at X-band. They include: i) a NRR, ii) a two-resonator based frequency selective isolator (FSI), iii) a five-resonator based FSI, and iv) a two-pole/two-TZ frequency selective quasi-circulator (FSQC).

In traditional non-reciprocal metasurfaces based on antenna-circuit-antenna structure, the radiation module and the non-reciprocal circuit module are coplanar, which occupies extra surface area and has the inherent defect of narrow operating bandwidth. Therefore, a new 2.5D non-reciprocal metasurface based on the aperture coupling structure is proposed to realize the separate design and broad operating bandwidth, in which the non-reciprocal circuit module is perpendicular to the radiation module. In addition, this work improves isolation to over 35 dB without affecting the radiation mode and resonance frequency. Based on multimode resonance theory, a broadband microstrip antenna is further presented to obtain a broader operating bandwidth. By exciting multiple resonant modes with similar frequencies in the resonant cavity, the relative bandwidth reaches up to 38.2%. The experimental results coincide well with the simulation results, which fully demonstrate the validity of the proposed design.

In biomedical research, germ-free and gnotobiotic mouse models enable the mechanistic investigation of microbiota-host interactions and their role on (patho)physiology. Throughout any gnotobiotic experiment, standardized and periodic microbiological testing of defined gnotobiotic housing conditions is a key requirement. Here, we review basic principles of germ-free isolator technology, the suitability of various sterilization methods, and the use of sterility testing methods to monitor germ-free mouse colonies. We also discuss their effectiveness and limitations, and share the experience with protocols used in our facility. In addition, possible sources of isolator contamination are discussed and an overview of reported contaminants is provided.

A direct connection test of a rotating detonation engine was conducted. The outer and inner diameters of the annular combustors were 206 and 166 mm, respectively. High enthalpy air was used as an oxidizer, and a mixture of hydrogen, carbon monoxide, and methane was used as fuel with a volume fraction of 5/4/1. The mixture was injected through small holes, and air was injected through annular slots. The effects of combustor length, width of annular slots, and the equivalent ratio on formation, development, propagation, and flameout of rotating detonation waves were analyzed, and several modes of rotating detonation were observed. It was found that when the width of the air annular slot was within the range of 3–5 mm, the pressure of the detonation wave was augmented with an increased slot width. As width increased, detonation waves became unstable. In study test conditions, an annular slot width of 6 mm was the critical condition for the formation of stable detonation. When the slot width was 4 mm and combustor length 160 mm, the phenomena of the conversion between single and double waves, double-wave collision, and conversion of the propagation direction occurred at different equivalent ratios. When the equivalent ratio was 1.2/1 and the slot width was within the range of 3–6 mm, the slot width was inversely related to the detonation wave velocity. When the slot width was 4 mm and the equivalent ratio was 1.0/1–1.2/1, the slot width was positively correlated with the detonation wave velocity. When the combustor length was shortened to 80 mm, the propagation mode of the detonation wave was changed to a single wave first and then to a double wave in the same direction, and the velocity reduced from 1130.69 to 1024.16 m/s. The injector used in the test inhibited the propagation of back pressure from the combustor.

Abstract We designed a simple on-chip integrated optical isolator made up of a metal–insulator–metal waveguide and a disc cavity filled with magneto-optical material to enhance the transverse magneto-optical effect through the coin paradox spin–orbit interaction (SOI). The simulation results of the non-reciprocal transmission properties of this optical structure show that a high-performance on-chip integrated optical isolator is obtained. The maximum isolation ratio is greater than 60 dB with a corresponding insertion loss of about 2 dB. The great performance of the optical isolator is attributed to the strong transverse magneto-optical effect, which is enhanced by the coin paradox SOI. Moreover, the enhancement of the transverse magneto-optical effect through the coin paradox SOI is more substantial for smaller azimuthal mode number n. Benefiting from this, the transverse magneto-optical effect remains strong in a wide wavelength range. Additionally, a smaller cavity has a stronger transverse magneto-optical effect in the same wavelength range. Our research provides a new perspective for creating highly integrated magneto-optical devices.

Applications of the American Seismic Isolator Standard “SIS” are summarized. The SIS is the only construction standard that specifies design criteria for retaining the functionality of hospitals after earthquakes. The SIS specifies limits for in-structure accelerations and deformations. Earthquake data shows that the SIS limits are the maximum that can be tollerated and retain the functionaluity of hospitals after earthquakes. The Adana and Elazig hospital complexes retained 100% functionality after the severe earthquakes that occurred in Turkey in 2023 and 2020. These earthquakes resulted in 55,000 fatalities and 236 health care facilities losing functionality. Since the 1989 California earthquake, 18 structures with SIS isolators have retained 100% functionality after major earthquakes that caused over 800,000 deaths, and over 700,000 structures to be demolished. The functionality of these SIS structures saved many lives by enabling post-earthquake emergency services. Since 1985, SIS isolators have been implemented in over 40 million square meters of important buildings, bridges, and industrial facilities, in 34 countries. The cost to build these 40 million square meters of important structures with SIS isolators was about the same as constructing ductile moment frames for only collapse avoidance without isolators.

To realize nonreciprocal transmission, it is necessary to break the time-reversal symmetry of the transmission system, but it is very challenging to keep the linear polarized (LP) input and output unchanged in the free space transmission system. Magnetized semiconductor InSb can realize terahertz (THz) nonreciprocal transmission for the two conjugated photonic spin states, but it cannot realize efficient one-way transmission of LP state due to gyro-mirror symmetry. In this work, by introducing a pair of orthogonal uniaxial anisotropies from the meta-gratings on both sides of InSb, both the gyro-mirror and time-reversal symmetries are broken for the LP state, thus making this cascaded grating–InSb–grating structure serves as a high-performance isolator for the LP light. The experiment results indicate isolation of 50 dB at 0.4 THz for the same LP input and output under a weak biased magnetic field of 0.17 T. Moreover, we further illustrate the factors affecting the isolation bandwidth of the device, also demonstrated another broadband structure with the 10 dB isolation bandwidth from 0.2–0.7 THz, and the relative bandwidth achieves 110%. The mechanisms of THz nonreciprocal transmission and polarization manipulation proposed in this work will contribute to the development of efficient THz magneto-optical devices.

Kehandalan merupakan kunci untuk menekan SAIDI dan SAIFI. Energi listrik dibangkitkan oleh pusat pembangkit yang jauh dari pusat beban. Energi listrik dialirkan ke pelanggan melalui jaringan. Proses penyaluranenergi listrik ada kemungkinan mengalami gangguan-gangguan, seperti gangguan Over Voltage, Over Load, Reverse Power, dan gangguan hubung singkat. Data PT. PLN ULP Kuta tahun 2018 menunjukkan terdapat 107 gangguan akibat binatang. Arus gangguan tanah menyebabkan bekerjanya ground fault relay (GFR) dan distribusi energi listrik menjadi padam. Tekep Isolator merupakan sebuah merek dagang penutup isolator gardu untuk melindungi dari gangguan binatang yang diproduksi oleh PT. Adi Putra. Tujuan penelitian ini adalah untuk mengetahui besarnya arus gangguan fasa ke tanah, setelah pemasangan tekep isolator gardu dan mengetahui kemampuan tekep isolator gardu ini untuk menanggulangi bekerjanya rele tanah. Metode penelitian ini adalah penelitian kuantitatif. Temuan penelitian ini antara lain : (1) Nilai arus gangguan satu fasa ke tanah setelah pemasangan tekep isolator gardu tipe YS-FCO-AP di fuse cut out pada kondisi tubuh tupai kering dan basah yaitu: 46,14206371 mikro Ampere dan 46,14208458 mikro Ampere. Nilai arus gangguan satu fasa ke tanah setelah pemasangan tekep isolator gardu tipe YS-BUS-ARR-AP bushing trafo dan arrester pada kondisi tubuh tupai kering dan basah yaitu: 16,83937183 mikro Ampere dan 16,83937461 mikro Ampere; (2) Saat terjadi gangguan satu fasa ke tanah di fuse cut out, bushing trafo dan arrester akibat tupai tidak menyebabkan jaringan distribusi padam, karena arus gangguan satu fasa ke tanah tidak melebihi setting rele tanah yaitu 30 Ampere.

In this paper, the transient flow simulation in an annular isolator under rotating feedback pressure perturbations simplified from the rotating denotation wave (RDW) is performed. The instantaneous flow characteristics and the self-similarity of the isolator flow-field are investigated in detail. It is found that a helical moving shock wave (MSW) and a quasi-toroidal terminal shock wave (TSW) are induced in the isolator. Hence, the flow-fields on the meridian planes could be classified into three zones, i.e., the undisturbed zone, the terminal shock wave/moving shock wave/boundary layer interaction (TSW/MSW/BLI) zone and the moving shock wave/boundary layer interaction (MSW/BLI) zone. The TSW/MSW/BLI zone is characterized by the coupling of the TSW/BLI and the MSW/BLI due to their small axial distance, which intensifies the adverse pressure gradient on the meridian planes, thus rolling up large separation bubbles developing along the MSW driven by the circular pressure gradient. In the MSW/BLI zone, the shock induces the boundary layer to separate, forming a helical vortex located at the foot of the MSW. During the upstream propagation process, the pattern of the MSWs transforms from a moving normal shock wave to a moving oblique shock wave with decreased strength. Moreover, after the collision with the MSWs, P, Temp and S of the flow elevate with the prompt decrease of va, while vθ increases to a higher level. Despite the deflection effect of the MSWs on the streamlines, the flow direction of the air still maintains an almost axial position at the exit, except in the adjacent region of the MSW. Likewise, three types of zones can be determined in the flow pattern at the exit: the rotating detonation wave/boundary layer interaction (RDW/BLI) zone, the expansion zone, and the vortices discharge zone. Comparing the transient flow patterns at different moments in one cycle and between adjacent cycles, an interesting discovery is that the self-similarity property is observed in the flow-field of the annular isolator under rotating feedback pressure perturbations. The global flow structure of the isolator at different moments shows good agreement despite its rotation with the RDW, and the surface pressure profiles of the corresponding meridian planes all match perfectly. Such a characteristic indicates that the rotation angular velocity of the TSW and the MSW are equal and hold invariant, and the isolator flow could be regarded as a quasi-steady flow. On this basis, the theoretical model of the inclination angles of the MSW by the coordinate transformation and velocity decomposition is developed and validated. The relative errors of the inclination angles between the predicted and measured results are below 3%, which offers a rapid method to predict the shape of the MSW, along with a perspective to better understand the physical meaning of the shape of the MSW.

Experiments were conducted in this study to reveal the flow characteristics of a variable cross-section S-shaped isolator, when applying the steady-state back pressure at the isolator outlet. The self-excited oscillation characteristics of the shock train generated under the influence of steady-state back pressure at an incoming flow speed of Mach 2, were also studied. The findings suggest that pressure oscillation within the area affected by the shock train’s flow field was significantly more potent than outside the affected area. Moreover, the forward movement velocity of the shock train in the variable cross-section S-shaped isolator was not uniform. The forward movement speed was slower when encountering sharp turns and faster during gentle turns. In the shock train flow field, high-frequency pressure oscillations, which mainly stemmed from the oscillations of the separated shock legs, propagated more readily within the flow field than low-frequency pressure oscillations. The significant separation of the shock train flow field will switch between the top and bottom walls, and the frequency of pressure oscillation in the large separation region is low. On another note, the closer the distance between two points is in the shock flow field, the stronger the coherence of pressure oscillations will be. In the distance upstream of the shock train flow field, the turbulent boundary layer (TBL) determines pressure oscillations instead of the shock train flow field, so the coherence was very high.

We study a waveguide structure supporting acoustic spoof plasmon polaritons (aSSPPs) perturbed by a defect, whose specifically tailored geometry enables controllable transmission characterized by a uniform phase distribution and very steep narrowband response. The structure is analyzed using transmission-line theory and numerical simulations, providing evidence for its use in advanced filters, isolators and sensor technology. In order to demonstrate the applicability of the aSSPP waveguide with defect, two selective narrowband filter designs are discussed and explored. Furthermore, we propose an acoustic isolator that exploits steady fluid flow to break reciprocity and provide large isolation in a narrowband region. We also propose a sensor for liquid analytes, in which the grooves of the aSSPP waveguide serve as microfluidic channels, while the sensing principle is based on the spectral shift of the transmission peak for different mixtures of water and glycerol. The sensor shows a good sensitivity and fast response, with a potential for further development for applications in water quality monitoring.

Isolation of buildings from earth vibrations is a new method that has been considered in the last few decades and is the only way to reduce simultaneously the inter-story displacement and acceleration of stories. In this method, increasing the period of rotation and damping of the structure at the separated level, the energy from the earthquake force to the structure decreases. Furthermore, recent earthquakes, including the Bam earthquake, have horizontal and vertical components, which resulted in the destruction of more structures, depending on the time of the start of the vertical or horizontal components or their combination. This issue highlights the importance of examining the vertical component of the earthquake in addition to the horizontal component. According to the mentioned cases, the main objective of this research is to investigate the behavior of asymmetric sliding structures with different separators under the horizontal component and the combination of horizontal and vertical components of the earthquake, taking into account the effects of soil and structure interaction. For this purpose, structures of 1, 5, and 10 stories irregular building(irregular amount of 40%) with seismic separators R-FBI, LRB and P-F on soil type IV are considered. In order to obtain the results of the research, the numerical method of finite element method has been used with modelling of materials in nonlinear area and performing explicit dynamic analysis. The results of the study showed that with increasing number of stories, the seismic separation function of R-FBI is better than other LRB and P-F separators. Also, the results of this study show that the simultaneous effect of horizontal and vertical components on structures 1 and 10 is remarkable.

Abstract This manuscript reviews seismic isolation and response control methods of buildings, which are able to make buildings resilient against earthquakes and have become popular during the last three decades in Japan. Seismic isolation is a method of protecting a building from major earthquakes by installing isolators and energy absorbing devices under the superstructure. The manuscript describes three types of laminated rubber bearings and three kinds of damping devices. Seismic isolation provides not only structural safety, but also safety and security for people and properties in the building. Seismic isolation is also used for the retrofit of historic buildings. Response control methods utilize various kinds of dampers that are installed into a building and absorb vibration energy. The manuscript explains three foremost response control dampers: the steel hysteretic damper, the viscoelastic damper and the viscous fluid damper. The effects of seismic isolation and response control methods were verified through shaking table tests, structural health monitoring and earthquake response analyses.

ABSTRAK Penelitian ini bertujuan untuk mengetahui seberapa besar nilai coating isolator yang dapat ditembus listrik berdasarkan Basic Insulator Level (BIL). Metode yang digunakan dalam perhitungan tegangan tembus listrik ialah metode Anderson dalam hal ini Critical Fashover (CFO). Untuk mengetahui penurunan daya tahan dielektrik isolator dapat dilihat dari seberapa besar tegangan flashover yang dihasilkan. Hasil dari perhitungan disimulasikan dengan MATLAB logika fuzzy. Pada penelitian ini ketika isolator disetting pada coating 0,3 mm dengan waktu kejadian flash 2 μs maka tegangan flashover yang dihasilkan sebesar 1,3 MV. Hasil simulasi ini menunjukan bahwa pada coating 0,3 mm tegangan flashover yang dihasilkan melebihi dari BIL isolator yang sudah ditetapkan yakni sebesar 1,27 MV. Isolator dalam kondisi seperti ini dapat ditembus listrik atau daya tahan dielektriknya menurun. Secara bersamaan ketika kemampuan coating berkurang, maka dapat diklasifikasikan isolator dalam keadaan kotor. Kata kunci: isolator, coating, dielektrik, BIL, dan fashover ABSTRACT This research aims to determine the value of the insulator that can be penetrated by electricity based on the Basic Insulator Level (BIL). The method used in the calculation of breakdown voltage is the Anderson method, in this case, Critical Flashover (CFO). To know a decrease in the dielectric resistance of the insulator can be seen from whatever the voltage resulting from a large flashover. The results of the calculations simulated with fuzzy logic Matlab. In this research, when the insulator set on a coating of 0.3 mm with a flash event time of 2 μs, then flashover voltage resulted in 1.3 MV. The simulation results show that at the coating 0.3 mm the result of flashover voltage exceeds the BIL insulator that has been set at 1.27 MV. Insulator in this condition can be penetrated by electricity or the dielectric resistance decreases. Simultaneously when the coating ability is reduced, then can be classified as a dirty insulator. Keyword: insulator, coating, dielectric, BIL, and flashover

Abstract As an explosion control measure, rock dusting has been used in underground coal mines in many major coal producing countries with different standards. The effectiveness of the rock dust in reducing explosion intensity has been proven by historic events and laboratory experiments. The main functions of rock dust in controlling mine explosions (i.e., isolator, physical heat sink and chemical energy absorber) have been quantitatively studied and results are presented in this paper.

A Faraday rotation isolator is conventionally achieved by connecting a matched load to a three-port circulator. It obtains superior performance (isolation > 20 dB) at the inevitable cost of non-ideal size. In order to adapt to the miniaturizations and integrations required for future 5G communication systems, it is particularly important to reduce the size of the devices. This work demonstrates a photonic crystal-based isolator design, comprising a unique reflecting cavity and a built-in fan-shaped coupler, where four Ni–Zn ferrite posts achieve the rotations. The design with the compact size of about 46.6 × 41.6 × 4.32 mm3 obtains excellent forward transmission efficiency and reverse isolation of 0.50 dB and 44.20 dB, respectively.

Although the horizontal component of an earthquake response can be significantly reduced through the use of conventional seismic isolators, the vertical component of excitation is still transmitted directly into the structure. Records from instrumented structures, and some recent tests and analyses have actually seen increases in vertical responses in base isolated structures under the combined effects of horizontal and vertical ground motions. This issue becomes a great concern to facilities such as a Nuclear Power Plants (NPP), with specialized equipment and machinery that is not only expensive, but critical to safe operation. As such, there is considerable interest worldwide in vertical and three-dimensional (3D) isolation systems. This paper examines several vertical and 3D isolation systems that have been proposed and their potential application to modern nuclear facilities. In particular, a series of case study analyses of a modern NPP model are performed to examine the benefits and challenges associated with 3D isolation compared with horizontal isolation. It was found that compared with the general horizontal isolators, isolators that have vertical frequencies of no more than 3 Hz can effectively reduce the vertical in-structure responses for the studied NPP model. Among the studied cases, the case that has a vertical isolation frequency of 3 Hz is the one that can keep the horizontal period of the isolators as the first period while having the most flexible vertical isolator properties. When the vertical frequency of isolators reduces to 1 Hz, the rocking effect is obvious and rocking restraining devices are necessary.

To analyze the present problems of the elastic-ring isolator,such as the unideal damping effect,the unadjustable damping and so on,the piezoelectric shunt damping technique was adopted to study the vibration control performance of the elastic ring.Using piezoelectric film as a substitute for the damping material of the elastic-ring isolator,the elastic-ring piezoelectric shunt damping isolator was designed.Moreover,shunt circuit was designed which was based on the gyrators and the piezoelectric shunt damping system electromechanical coupling model was established to study the method of optimizing parameters of the shunt circuit.Furthermore,the optimal parameters were determined.Finally,the vibration control performance of the piezoelectric shunt damping system was experimentally analyzed.Experimental results show that the vibration of the structure can be reduced by 9 d B.

Analysis of properties and characteristics of the alumina, beryllium oxide and aluminum nitride based ceramic materials used in UHF electronic devices has been made. It was shown that the complex of parameters including structural and functional characteristics of the high-thermal conductive aluminum nitride ceramics prevail over all types of alumina ceramics and is not lower than the same characteristics of the beryllium oxide ceramics especially at the temperatures higher than 450 °C. The examples of the prevailing use of the aluminum nitride ceramics inside vacuum UHF-region devices: TWT’s and klystrons.

Understanding magnetooptics in cylindrical structures presents interest in the development of magnetic sensor and nonreciprocal devices compatible with optical fibers. The present work studies wave propagation in dielectric circular cylindrical structures characterized by magnetic permeability and electric permittivity tensors at axial magnetization. The Helmholtz equations deduced from the Maxwell equations in transverse circularly polarized representation provide electric and magnetic fields. With the restriction to terms linear in off-diagonal tensor elements, these can be expressed analytically. The results are applied to magnetooptic (MO) circular cylindrical waveguides with a step refractive index profile. The nonreciprocal propagation is illustrated on waveguides with an yttrium iron garnet (YIG) core and a lower refractive index cladding formed by gallium substituted yttrium iron garnet (GaYIG) at the optical communication wavelength. The propagation distance required for the isolator operation is about one hundred micrometers. The approach may be applied to other structures of cylindrical symmetry in the range from microwave to optical frequencies.

In order to solve the problems of high cost,un-convenient installation and low-precise detection caused by using IR temperature sensor and fiber sensor to detect temperature of isolators in high-voltage distribution equipment at present,an on-line monitoring device of temperature for isolators in high-voltage distribution equipment based on nRF905 was designed,and design of hardware and software of the device was introduced in details.The experimental results showed that circuits of data collection,data receiving and sending and data processing of the device are reasonable,and the device can realize on-line monitoring of temperature of isolators in high-voltage distribution equipment,which has error below(± 1.5 ℃) and meets actual needs of engineering.