Low Coupling Research Articles

Single-Chip Two Antennas for MM-Wave Self-Powering and Implantable Biomedical Devices

Implantable biomedical applications arise the need for multi-band sensors with a wideband frequency channel for RF energy harvesting operation. Using a separate antenna for energy harvesting can simplify device circuit complexity and reduces operation frequency bands interference. This paper demonstrates the design of single chip with two separate integrated antennas for implantable biomedical applications. The two antennas have different structures with orthogonal polarization to achieve low mutual coupling and negligible interaction between them. The first antenna is a multi-band meander line (MBML) designed for multiple channels data communication, with quad operating bands in the MM-wave range from 22-64 GHz with area 1150 × 200μm2. The second antenna is a wideband dipole antenna (WBDA) for RF energy harvesting, operates in the frequency range extend from 28 GHz to 36 GHz with area 1300×250μm2. The proposed antennas are designed by using high frequency structure simulator (HFSS) and fabricated by using UMC180nm CMOS technology with total area 0.55 mm2. The MBML frequency bands operating bandwidths can reach 2 GHz at impedance bandwidth ≤ -10 dB. While, the WBDA antenna has gain -2 dB over the operating band extend from 28 GHz up to 36 GHz. The antenna performance is simulated separately and using the human-body phantom model that describes layers of fats inside body, and shows their compatibility for in body operation. Die measurements is performed using on wafer-probing RF PICOBROBES and shows the matching between simulation and measurement values.

Exploring the relationship between urbanization and water environment based on coupling analysis in Nanjing, East China.

The degradation of water environment (WE) has constrained the sustainable development of cities, while the rapid urbanization also exacerbates water environment change. However, the complicated relationship between urbanization and WE is far from clearly understood. In this study, a comprehensive index system for urbanization and WE was applied along with the System Index Evaluation Model (SIEM) and a Coupling Coordination Degree Model (CCDM) to analyze the coupling between urbanization and WE in Nanjing, East China, from 1990 to 2018. The comprehensive index of urbanization increased from 0.0392 in 1990 to 0.9890 in 2018, showing a clear increasing trend. Demographic and spatial urbanization made the largest contribution to urbanization development from 1990 to 2010, while economic urbanization became the largest contributor to urbanization development between 2011 and 2018. Under the combined effects of pressure, state, and response subsystems, the comprehensive WE index showed an upward trend with some fluctuations from 1990 to 2018. The degree of coupling coordination between urbanization and WE displayed an overall upward tendency, growing from 0.18 in 1990 to 0.95 in 2018. The coupling coordination state transitioned from a serious imbalance during the low coupling period (1990–1992) into the superior coordination of the highly coupled period (2011–2018). With the continuous urbanization in the future, in addition to ensuring the optimal management of surface water, protection of groundwater should be reinforced. The results advance our understanding of the dynamic relationship between urbanization and WE and provide important implications for urban planning and water resource protection.

A novel friction-actuated 2-DOF high precision positioning stage with hybrid decoupling structure

This paper proposes a novel friction-actuated two degree-of-freedom positioning stage with large motion stroke, high resolution and low coupling rate. A parallelly decoupled driving unit and the serially configured sliders are utilized together to realize hybrid output decoupling, and a clamping unit is adopted to adjust the friction force between friction piece and moving platform, which can improve the output characteristic while reduce the amount of PZT stacks. In addition, the coarse-fine cooperatively actuation principle is developed to realize large stroke positioning with high accuracy, and the decoupling control strategy is adopted to reduce the accumulated coupling error. The analytical modeling is conducted to explore the step displacement of driving unit, and a prototype is fabricated to investigate the performance of the positioning stage. The experimental results show that the step displacements in X and Y axes are 11.3 μm and 10.6 μm, and the cross-coupling rates after decoupling compensation are 0.07% and 0.14%, respectively. The maximum output velocity and horizontal loading capacity is 1.54 mm/s and 1.2 N, respectively, and the resolution is tested as 20 nm.

Improved tear resistance by low environmental impact coupling of plasma reactive and additive treatment of a TPU/PET coated fabric

An environmentally friendly approach, which consists in coupling a dielectric barrier discharge (DBD) based atmospheric plasma treatment with a coating of an aqueous phase polyurethane dispersion (PUD) containing blocked polyisocyanates, is proposed to improve the adhesion of a thermoplastic polyurethane (TPU) film onto a poly-(ethylene terephthalate) (PET) textile fabric. In this study, a screening digital design of experiment plan (DOE) was developed to determine the influence of process parameters on the adhesion between film and fabric and to evaluate the best possible adhesion value. The process parameters considered are: the dielectric barrier discharge power, the speed of the fabric undergoing the treatment, the concentration of polyisocyanates (NCO) in the PUD and the air gap. The adhesion was measured by a peeling test and further scanning electron microscope observations were carried out. Results showed that an increase of both the processing power and the NCO content in PUD, as well as the decrease in the DBD speed, had a positive effect on the adhesion. In addition, X-ray photoelectron spectroscopy and contact angle measurements demonstrated an increase in the oxygen/carbon atomic percentage ratio between the reference fabric and the treated fabric. Thus, the calibrated oxidation of the PET treated with DBD plasma treatment leads to a greater chemical and physical interaction with the TPU film, which results in better film-fabric adhesion.

Highly-efficient thin film LiNbO3 surface couplers connected by ridge-waveguide subwavelength gratings

The ridge waveguide integrated grating couplers (GCs) in lithium niobate on insulator (LiNbO3, LNOI) were designed, fabricated and characterized. Two ends of the tapered GCs were connected by the subwavelength gratings (SWG) waveguide of a sub-micrometric-diameter, the photonic-wire SWG structure was featured with the profile of side-walls corrugations, and the effect of geometrical dimensions on the output optical response was investigated. All the devices structure patterns for the integrated LNOI GCs could be simultaneously defined by one step of electron-beam lithography, and then easily fabricated by the optimized dry-etching processes, followed by samples surface cleaning. After the fabrication, a low coupling loss of − 5.1 dB/coupler at the telecommunication wavelength of 1561 nm was measured in the best thin-film LiNbO3 (TFLN) surface grating coupler for quasi-transverse-electric (quasi-TE) polarized signals, and a broad 3-dB optical bandwidth of wider than 95 nm was also obtained. The compact components exhibited magnificent performance, and might show the potential functionalities for the TFLN-based integrated optical waveguide devices.

Precision axion physics with running axion couplings

We study the renormalization group running of axion couplings while taking into account that the Standard Model can be extended to its supersymmetric extension at a certain energy scale below the axion decay constant. We then apply our results to three different classes of axion models, i.e. KSVZ-like, DFSZ-like, and string-theoretic axions, and examine if string-theoretic axions can be distinguished from others by having a different pattern of low energy couplings to the photon, nucleons and electron. We find that the low energy couplings of string-theoretic axions have a similar pattern as those of KSVZ-like axions but yet reveal a sizable difference which might be testable in future axion search experiments. We also note that the coupling of KSVZ-like QCD axions to the electron is dominated by a three-loop contribution involving the exotic heavy quark, gluons, top quark and Higgs field.

Data Acquisition System for Underwater In Situ Gamma Radiation Spectrometer

Radiation measurement at underwater environment helps to get a better understanding on sedimentation, geological structure, radiation monitoring, and so on. However, reports about radiation of natural underwater environment are rare, especially in situ gamma radiation measurement. Two gamma spectrometers are going to be used in underwater in situ radiation measurement. Aiming at different scientific goals, the spectrometers can develop multiple kinds of measurements, including dose and energy spectrum of gamma rays. In this article, a compatible data acquisition (DAQ) system is proposed. The DAQ provides features of readout, visualization, data process algorithm, and file input and output. To benefit from high reusability and low coupling, the Model-View-ViewModel (MVVM) pattern is adopted in the DAQ system. With an application layer protocol based on Modbus, the DAQ can be fully compatible with different spectrometers. Besides supporting of real-time control, the DAQ system also provides a way to program the spectrometers to execute an unmanned mission, so that the spectrometers can load a timetable from a built-in flash memory and run automatically.

A Nested Eight-Channel Transmit Array With Open-Face Concept for Human Brain Imaging at 7 Tesla

Purpose: Parallel transmit technology for MRI at 7 tesla will significantly benefit from high performance transmit arrays that offer high transmit efficiency and low mutual coupling between the individual array elements. A novel dual-mode transmit array with nested array elements has been developed to support imaging the human brain in both the single-channel (sTx) and parallel-transmit (pTx) excitation modes of a 7 tesla MRI scanner. In this work, the design, implementation, validation, specific absorption rate (SAR) management, and performance of the head coil is presented.Methods: The transmit array consisted of a nested arrangement to improve decoupling between the second-neighboring elements. Two large cut-outs were introduced in the RF shield for an open-face design to reduce claustrophobia and to allow patient monitoring. A hardware interface allows the coil to be used in both the sTx and pTx modes. SAR monitoring is done with virtual observation points (VOP) derived from human body models. The transmit efficiency and coverage is compared with the commercial single-channel and parallel-transmit head coils.Results: Decoupling inductors between the second-neighboring coil elements reduced the coupling to less than −20 dB. Local SAR estimates from the electromagnetic (EM) simulations were always less than the EM-based VOPs, which in turn were always less than scanner predictions and measurements for static and dynamic pTx waveforms. In sTx mode, we demonstrate improved coverage of the brain compared to the commercial sTx coil. The transmit efficiency is within 10% of the commercial pTx coil despite the two large cut-outs in the RF shield. In pTx mode, improved signal homogeneity was shown when the Universal Pulse was used for acquisition in vivo.Conclusion: A novel head coil which includes a nested eight-channel transmit array has been presented. The large cut-outs improve patient monitoring and reduce claustrophobia. For pTx mode, the EM simulation and VOP-based SAR management provided greater flexibility to apply pTx methods without the limitations of SAR constraints. For scanning in vivo, the coil was shown to provide an improved coverage in sTx mode compared to a standard commercial head coil.

High-efficiency unidirectional vertical emitter achieved by an aperture-coupling nanoslot antenna array.

Coupling light from in-plane guided light into free space or optical fibers is crucial for many photonic integrated circuits and vice versa. However, traditional grating couplers or waveguide grating antennas suffer from low upward coupling efficiency due to the light radiating in both upward and downward directions simultaneously. In this paper, a compact aperture-coupling nanoslot antenna array is proposed for high-efficiency unidirectional radiation, where a two-dimensional high-contrast grating (HCG) is employed as a mirror to reflect the undesired downward radiation. Upon the HCG separated by a low-index spacing layer, a thin silver layer is deposited. Finally, a series of H-shaped slots are patterned on the silver thin film to arrange the aperture fields and radiate the in-plane guided light into free space. The proposed nanoslot antenna array features a front-to-back ratio (F/B) over 10 dB within the wavelength range of 1500 ∼ 1600 nm. At the same time, a high radiation efficiency of over 75% and a maximum radiation efficiency of 87.6% are achieved within the 100 nm bandwidth. The high-efficiency unidirectional antenna array is promising for the integrated photonic applications including wireless optical communications, light detection and ranging, and fiber input/output couplers.

Optically Heralded Entanglement of Superconducting Systems in Quantum Networks.

Networking superconducting quantum computers is a longstanding challenge in quantum science. Thetypical approach has been to cascade transducers: converting to optical frequencies at the transmitter and to microwave frequencies at the receiver. However, the small microwave-optical coupling and added noise have proven formidable obstacles. Instead, we propose optical networking via heralding end-to-end entanglement with one detected photon and teleportation. This new protocol can be implemented on standard transduction hardware while providing significant performance improvements over transduction. In contrast to cascaded direct transduction, our scheme absorbs the low optical-microwave coupling efficiency into the heralding step, thus breaking the rate-fidelity trade-off. Moreover, this technique unifies and simplifies entanglement generation between superconducting devices and other physical modalities in quantum networks.

Design of Fiber-Tip Refractive Index Sensor Based on Resonant Waveguide Grating with Enhanced Peak Intensity

Resonant waveguide gratings (RWG) are widely used as on-chip refractometers due to their relatively high sensitivity to ambient refractive index changes, their possibility of parallel high-throughput detection and their easy fabrication. In the last two decades, efforts have been made to integrate RWG sensors onto fiber facets, although practical application is still hindered by the limited resonant peak intensity caused by the low coupling efficiency between the reflected beam and the fiber mode. In this work, we propose a new compact RWG fiber-optic sensor with an additional Fabry-Pérot cavity, which is directly integrated onto the tip of a single-mode fiber. By introducing such a resonant structure, a strongly enhanced peak reflectance and improved figure of merit are achieved, while, at the same time, the grating size can be greatly reduced, thus allowing for spatial multiplexing of many sensors on a tip of a single multi-core fiber. This paves the way for the development of probe-like reflective fiber-tip RWG sensors, which are of great interest for multi-channel biochemical sensing and for real-time medical diagnostics.

Synchronization of coupled Kuramoto oscillators under resource constraints.

A fundamental understanding of synchronized behavior in multiagent systems can be acquired by studying analytically tractable Kuramoto models. However, such models typically diverge from many real systems whose dynamics evolve under nonnegligible resource constraints. Here we construct a system of coupled Kuramoto oscillators that consume or produce resources as a function of their oscillation frequency. At high coupling, we observe strongly synchronized dynamics, whereas at low coupling, we observe independent oscillator dynamics as expected from standard Kuramoto models. For intermediate coupling, which typically induces a partially synchronized state, we empirically observe that (and theoretically explain why) the system can exist in either: (i) a state in which the order parameter oscillates in time, or (ii) a state in which multiple synchronization states are simultaneously stable. Whether (i) or (ii) occurs depends upon whether the oscillators consume or produce resources, respectively. Relevant for systems as varied as coupled neurons and social groups, our paper lays important groundwork for future efforts to develop quantitative predictions of synchronized dynamics for systems embedded in environments marked by sparse resources.

Development of a two-DOF piezoelectric posture alignment mechanism with low coupling based on a cross-orthogonal-axis structure

A two-degrees of freedom (DOF) piezoelectric posture alignment mechanism (PAM) with low coupling based on a cross-orthogonal-axis (COA) structure was proposed. The proposed PAM with millimeter-level stroke and nanoscale resolution could realize rotary motions around X-axis and Y-axis based on the stick-slip driving, and the performance of low coupling was also achieved based on the COA structure. Its working principle was introduced and it was designed to achieve the range of rotation angle of 136.4°. The kinematic characteristic of stick-slip motion was analyzed and the step displacement model of the rotor was derived. A prototype of the PAM was fabricated and some experiments were carried out to investigate its performance. The experiment results showed that the X- and Y-axis relative coupling errors are 4.69% and 3.86%, respectively. In addition, the proposed PAM satisfied the requirement of rotation angle of ±2.5° and the angular displacement resolutions achieved 0.09 µrad around X-axis and Y-axis. The proposed two-DOF piezoelectric PAM could be applied to the precision positioning and the adaptive optics system based on its merits of large range, high resolution, low coupling and good carrying capacity.

Ultracompact Energy Transfer in Anapole-based Metachains.

Realization of electromagnetic energy confinement beyond the diffraction limit is crucial for high-performance on-chip devices. Herein we construct an array of nonradiative anapoles that originate from the destructive far-field interference of electric and toroidal dipole modes to achieve ultracompact and high-efficiency electromagnetic energy transfer without the coupler. We experimentally investigate the proposed metachain at mid-infrared frequencies and give the first near-field experimental evidence of anapole-based energy transfer, in which the spatial profile of the anapole mode is also unambiguously identified on the nanoscale. We further demonstrate that the metachain is intrinsically lossless and scalable at infrared wavelengths, realizing a 90° bending loss down to 0.32 dB at the optical communication wavelength. The present scheme bridges the gap between the energy confinement and the transfer of anapoles and opens a new gate for more compactly integrated photonic and energy devices, which can operate in a broad spectral range.

Partial Maxwell fish-eye lens inspired by the Gutman lens and Eaton lens for wide-angle beam scanning.

This paper presents a novel two-dimensional (2-D) partial Maxwell fish-eye (PMFE) lens with the capability of wide-angle beam scanning inspired by the Gutman lens and Eaton lens, which is obtained by cutting a part from the 2-D Maxwell fish-eye (MFE) lens along a straight line. In terms of the refractive index profile, the MFE lens is similar to the Gutman lens near the center and the Eaton lens near the edge, respectively. We demonstrate the potential of the PMFE lens in wide-angle beam scanning based on its Gutman-like focusing and Eaton-like rotating characteristics corresponding to different feed points. As an example, a fully metallic PMFE lens antenna in the Ka-band composed of a bed of nails and a series of linearly arranged waveguide feeders is designed and experimentally verified. The measured results reveal wide-angle scanning ranges, especially about ±90° at 36 GHz, low reflections and low mutual couplings. The frequency scanning due to the dispersion of the lens is also discussed.

Interplay of seismic and a-seismic deformation during the 2020 sequence of Atacama, Chile

An earthquake sequence occurred in the Atacama region of Chile throughout September 2020. The sequence initiated by a mainshock of magnitude Mw= 6.9, followed 17 hours later by a Mw= 6.4 aftershock. The sequence lasted several weeks, during which more than a thousand events larger than Ml= 1 occurred, including several larger earthquakes of magnitudes between 5.5 and 6.4. Using a dense network that includes broad-band, strong motion and GPS sites, we study in details the seismic sources of the mainshock and its largest aftershock, the afterslip they generate and their aftershock, shedding light of the spatial temporal evolution of seismic and aseismic slip during the sequence. Dynamic inversions show that the two largest earthquakes are located on the subduction interface and have a stress drop and rupture times which are characteristics of subduction earthquakes. The mainshock and the aftershocks, localized in a 3D velocity model, occur in a narrow region of interseismic coupling (ranging 40%-80%), i.e. between two large highly coupled areas, North and South of the sequence, both ruptured by the great Mw∼8.5 1922 megathrust earthquake. High rate GPS data (1 Hz) allow to determine instantaneous coseismic displacements and to infer coseismic slip models, not contaminated by early afterslip. We find that the total slip over 24 hours inferred from precise daily solutions is larger than the sum of the two instantaneous coseismic slip models. Differencing the two models indicates that rapid aseismic slip developed up-dip the mainshock rupture area and down-dip of the largest aftershock. During the 17 hours separating the two earthquakes, micro-seismicity migrated from the mainshock rupture area up-dip towards the epicenter of the Mw 6.4 aftershocks and continued to propagate upwards at ∼ 0.7 km/day. The bulk of the afterslip is located up-dip the mainshock and down-dip the largest aftershock, and is accompanied with the migration of seismicity, from the mainshock rupture to the aftershock area, suggesting that this aseismic slip triggered the Mw= 6.4 aftershock. Unusually large post-seismic slip, equivalent to Mw= 6.8 developed during three weeks to the North, in low coupling areas located both up-dip and downdip the narrow strip of higher coupling, and possibly connecting to the area of the deep Slow Slip Event detected in the Copiapo area in 2014. The sequence highlights how seismic and aseismic slip interacted and witness short scale lateral variations of friction properties at the megathrust.

Corporate Leadership Strategy Management Based on Entropy Coupling Algorithm

With the continued economic downturn, coupled with the slowdown of domestic economic development and fierce market competition, the development of small and medium-sized enterprises has become more and more difficult. Because the financial background and operating strength of small and medium-sized enterprises are far inferior to large-scale enterprises, coupled with the influence of global economic integration, many small and medium-sized enterprises have gradually closed down. Therefore, exploring the entropy coupling algorithm is of great significance to the role of corporate leadership strategy management. This paper studies the coupling conditions and coupling process of corporate strategy and business model, builds a new coupling model, and goes deep into the coupling model to study the cooperation mechanism between its internal modules and initially builds the company to break through the two major dilemmas at the same time. This paper uses entropy theory to evaluate corporate leadership strategy, constructs an evaluation index system based on entropy, determines the weight of each index, and calculates the entropy value. This paper uses the alpha coefficient to test the reliability of the questionnaire. The value range of α coefficient is [0, 1], and different values represent different reliability. Large enterprises as a whole are mostly in the highly coupled (41.80%) and moderately coupled (27.34%) stages; medium-sized enterprises as a whole are mostly in the highly coupled (39.50%) and moderately coupled (31.50%) stages; small enterprises as a whole are mostly in the moderately coupled (39.50%) and moderately coupled (40.72%), low coupling (33.20%), and high coupling (25.9%) stages; microenterprises as a whole are mostly in the low coupling (43.70%), moderate coupling (36.41%), and high coupling (30.51%) stages. The results show that the entropy coupling algorithm can improve the deficiencies in the leadership strategy and provide a practical and reliable path for carrying out leadership development projects.

Semiautomatic Generation of Code Ontology Using ifcOWL in Compliance Checking

Code compliance checking is a very important step in engineering construction, but most of code compliance checking relies on manual review at present. With the development of semantic web technology, ontology can be used to represent code information and check the code automatically. However, code ontology is established manually by researchers who have sufficient domain knowledge, in which it is easy to cause poor hierarchical structure of classes. It is also possible for code ontology not being suitable for compliance check. This paper proposes a semiautomatic construction method of railway code ontology based on ifcOWL. The railway code ontology is developed by converting ifcOWL which extends semantic information of railway code. This method can ensure the completeness of the hierarchical relationship of the classes in code ontology with good scalability, which makes use of taxonomy in ifcOWL. The establishment of ontology is divided into two processes with low coupling, namely, extension and conversion, which reduces the domain knowledge requirements of the researchers. Finally, a practical specification is selected to generate a code ontology that achieves some clauses checking.

Mn2O3-Na2WO4 doping of CexZr1-xO2 enables increased activity and selectivity for low temperature oxidative coupling of methane

Ethylene in principle can be obtained via oxidative coupling of methane (OCM), but it is urgently calling for a low-temperature active and selective catalyst. To accomplish this goal, the CexZr1-xO2 solid solutions with varied Ce/Zr molar ratio were modified with Mn2O3-Na2WO4 to fabricate OCM catalysts. The effects of Ce/Zr ratio and Mn2O3-Na2WO4 doping were investigated on the catalyst reactivity for the OCM, showing that the reaction light-off temperature, activity and selectivity are subject to the Ce/Zr molar ratio and Mn2O3-Na2WO4 doping. The promising catalyst with Ce/Zr molar ratio of 0.15/0.85 achieves 25% CH4 conversion with 67% selectivity to C2-C3 at 660 °C and is stable for at least 100 h. The catalysts were systematically studied by CH4-TPSR, O2-TPO/-TPD, CH4-pulse, in-situ FT-IR, EPR and XPS, showing that the Mn2O3-Na2WO4 doped Ce0.15Zr0.85O2 can generate more O2– species thereby leading to a markedly improved activity and selectivity at much lowered reaction temperature.

Complex rift patterns, a result of interacting crustal and mantle weaknesses, or multiphase rifting? Insights from analogue models

Abstract. During lithospheric extension, localization of deformation often occurs along structural weaknesses inherited from previous tectonic phases. Such weaknesses may occur in both the crust and mantle, but the combined effects of these weaknesses on rift evolution remain poorly understood. Here we present a series of 3D brittle–viscous analogue models to test the interaction between differently oriented weaknesses located in the brittle upper crust and/or upper mantle. We find that crustal weaknesses usually express first at the surface, with the formation of grabens parallel to their orientation; then, structures parallel to the mantle weakness overprint them and often become dominant. Furthermore, the direction of extension exerts minimal control on rift trends when inherited weaknesses are present, which implies that present-day rift orientations are not always indicative of past extension directions. We also suggest that multiphase extension is not required to explain different structural orientations in natural rift systems. The degree of coupling between the mantle and upper crust affects the relative influence of the crustal and mantle weaknesses: low coupling enhances the influence of crustal weaknesses, whereas high coupling enhances the influence of mantle weaknesses. Such coupling may vary over time due to progressive thinning of the lower crustal layer, as well as due to variations in extension velocity. These findings provide a strong incentive to reassess the tectonic history of various natural examples.