Coupling Loop Research Articles

Advanced Multi-Functional Integrated Photonic Filters Based on Coupled Sagnac Loop Reflectors

We theoretically investigate integrated photonic resonators formed by two mutually coupled Sagnac loop reflectors (MC-SLRs). Mode interference in the MC-SLR resonators is tailored to achieve versatile filter shapes with high performance, which enable flexible spectral engineering for diverse applications. By adjusting the reflectivity of the Sagnac loop reflectors (SLRs) as well as the coupling strength between different SLRs, we achieve optical analogues of Fano resonance with ultrahigh spectral slope rates, wavelength interleaving / non-blocking switching functions with significantly enhanced filtering flatness, and compact bandpass filters with improved roll-off. In our designs the requirements for practical applications are considered, together with detailed analyses of the impact of structural parameters and fabrication tolerances. These results highlight the strong potential of MC-SLR resonators as advanced multi-functional integrated photonic filters for flexible spectral engineering in optical communications systems.

Stabilization of melon cloudy juice with biopolymer agar

In the production of natural fruit juices, the uniform distribution of fruit pulp particles in the volume is of great importance, which determines the aggregate stability of the system. To maintain the aggregate stability of fruit juices, stabilizers are used, which are polymers or surfactants. In this regard, the influence of natural polymer agar on the stability of melon juice containing particles of melon pulp has been studied. The initial melon juice had a pH of 5.78 and a titrated acidity of 970.29 mg of citric acid/L, the content of soluble solids in it corresponded to 10.08 TSS Brix. Samples of melon juice with concentrations of 50, 70 and 90 % were used for research. The study of the stability of melon juice in the presence of agar was carried out for 6 days on the Turbiscan device (France). It is shown that at concentrations of agar introduced into melon juice of 0.005 % and 0.01 %, the system retains its aggregate stability, but when switching to a concentration of 0.02 %, the stability of the system decreases. The size of melon pulp particles changes accordingly. If the addition of agar concentration of 0.05 % and 0.01 % to the melon pulp reduces the particle size of the melon pulp, then an increase in the agar concentration to 0.02 % causes a certain increase in the particle size of the fruit pulp. This effect of agar concentration on the aggregate stability of melon juice is explained by the fact that at low concentrations, polymer macromolecules, covering the surface of melon pulp particles, protect them from sticking. When the polymer concentration increases, melon pulp particles begin to stick together due to the coupling of loops and tails of agar macromolecules adsorbed on their surface

Chaos Synchronization of Delayed Quantum Dot Light Emitting Diodes

Chaos synchronization of two quantum dot light emitting diodes (QDLEDs) theoretically isstudied, which is delay coupled via a closed or open –loop and mutual coupling system. Whereas thesynchronized- chaotic systems, the dynamics of there are identical to uncoupled DLED under opticalfeedback effect. Complete synchronization was obtained under certain conditions for the couplingparameters. We evaluated the range of the QDLED’s chaos with extrinsic optical feedback in methodsof the chaos synchronization residue diagram and discussion as well of the coherence for the optimalcoupling strength range. With proper conditions of the coupling parameters and the evaluationmethods, the synchronization was satisfactorily obtained between the transmitter and receiver.

Realization of mutual synchronization of spin torque nano-oscillators under room temperature by noise reduction technique

The pragmatic use of Spin Torque Nano-Oscillators (STNOs) in real electronic systems is severely hindered due to their low output power and poor noise figure. The most accepted and promising way to increase the output power and decrease the signal noise of STNOs is through their mutual synchronization. However, it is confused that the mutual synchronization of STNOs is very difficult to achieve at room temperature although the non-linear nature of STNOs contributes to the large frequency range of injection locking. In this work, first, it is revealed that the difficulty of STNOs' mutual synchronization stems from the high output signal noise of STNOs. Based on this observation, a noise reduction technique is invented, which introduces a Band Pass Filter in the coupling loop of STNOs. Using the noise reduction technique, it is demonstrated that even non-identical STNOs can be mutually synchronized at room temperature.

CaMKII controls neuromodulation via neuropeptide gene expression and axonal targeting of neuropeptide vesicles.

Ca2+/calmodulin-dependent kinase II (CaMKII) regulates synaptic plasticity in multiple ways, supposedly including the secretion of neuromodulators like brain-derived neurotrophic factor (BDNF). Here, we show that neuromodulator secretion is indeed reduced in mouse α- and βCaMKII-deficient (αβCaMKII double-knockout [DKO]) hippocampal neurons. However, this was not due to reduced secretion efficiency or neuromodulator vesicle transport but to 40% reduced neuromodulator levels at synapses and 50% reduced delivery of new neuromodulator vesicles to axons. αβCaMKII depletion drastically reduced neuromodulator expression. Blocking BDNF secretion or BDNF scavenging in wild-type neurons produced a similar reduction. Reduced neuromodulator expression in αβCaMKII DKO neurons was restored by active βCaMKII but not inactive βCaMKII or αCaMKII, and by CaMKII downstream effectors that promote cAMP-response element binding protein (CREB) phosphorylation. These data indicate that CaMKII regulates neuromodulation in a feedback loop coupling neuromodulator secretion to βCaMKII- and CREB-dependent neuromodulator expression and axonal targeting, but CaMKIIs are dispensable for the secretion process itself.

The IL1\u03b2-IL1R signaling is involved in the stimulatory effects triggered by hypoxia in breast cancer cells and cancer-associated fibroblasts (CAFs)

BackgroundHypoxia plays a relevant role in tumor-related inflammation toward the metastatic spread and cancer aggressiveness. The pro-inflammatory cytokine interleukin-1β (IL-β) and its cognate receptor IL1R1 contribute to the initiation and progression of breast cancer determining pro-tumorigenic inflammatory responses. The transcriptional target of the hypoxia inducible factor-1α (HIF-1α) namely the G protein estrogen receptor (GPER) mediates a feedforward loop coupling IL-1β induction by breast cancer-associated fibroblasts (CAFs) to IL1R1 expression by breast cancer cells toward the regulation of target genes and relevant biological responses.MethodsIn order to ascertain the correlation of IL-β with HIF-1α and further hypoxia-related genes in triple-negative breast cancer (TNBC) patients, a bioinformatics analysis was performed using the information provided by The Invasive Breast Cancer Cohort of The Cancer Genome Atlas (TCGA) project and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) datasets. Gene expression correlation, statistical analysis and gene set enrichment analysis (GSEA) were carried out with R studio packages. Pathway enrichment analysis was evaluated with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. TNBC cells and primary CAFs were used as model system. The molecular mechanisms implicated in the regulation of IL-1β by hypoxia toward a metastatic gene expression profile and invasive properties were assessed performing gene and protein expression studies, PCR arrays, gene silencing and immunofluorescence analysis, co-immunoprecipitation and ChiP assays, ELISA, cell spreading, invasion and spheroid formation.ResultsWe first determined that IL-1β expression correlates with the levels of HIF-1α as well as with a hypoxia-related gene signature in TNBC patients. Next, we demonstrated that hypoxia triggers a functional liaison among HIF-1α, GPER and the IL-1β/IL1R1 signaling toward a metastatic gene signature and a feed-forward loop of IL-1β that leads to proliferative and invasive responses in TNBC cells. Furthermore, we found that the IL-1β released in the conditioned medium of TNBC cells exposed to hypoxic conditions promotes an invasive phenotype of CAFs.ConclusionsOur data shed new light on the role of hypoxia in the activation of the IL-1β/IL1R1 signaling, which in turn triggers aggressive features in both TNBC cells and CAFs. Hence, our findings provide novel evidence regarding the mechanisms through which the hypoxic tumor microenvironment may contribute to breast cancer progression and suggest further targets useful in more comprehensive therapeutic strategies.

Admittance-Based Stability Comparative Analysis of Grid-Connected Inverters With Direct Power Control and Closed-Loop Current Control

Direct power control (DPC) is widely used in grid-connected inverters. First, considering the effects of phase-locked loop (PLL), voltage outer loop, power inner loop, control delay, and frequency coupling, a broadband admittance model of the grid-connected inverter with DPC is established. The admittance characteristics of grid-connected inverters with DPC and closed-loop current control (CCC) are compared and analyzed. Due to the different inner loop control objects, the components produced by the power calculation in DPC and the Park's transformation in CCC cause the admittance differences between the grid-connected inverters with DPC and CCC. Then, the effects of grid impedance, output power, and control parameters on system stability are analyzed. It is revealed that the stability of the grid-connected inverter with DPC is very sensitive to grid impedance and easily affected by output power and inner loop bandwidth, while the grid-connected inverter with CCC has a better adaptability to weak grid, high output power, and inner loop bandwidth. Moreover, the PLL bandwidth has little effect on the stability of the grid-connected inverter with DPC, but has a great impact on the stability of the grid-connected inverter with CCC when the inverter is connected to weak grid. Finally, the correctness of the analysis is verified by experiments.

A New Washable UHF RFID Tag: Design, Fabrication, and Assessment.

This paper deals with the design and fabrication of durable radio frequency identification (RFID) passive tag with inductive coupling, operating at ultra-high frequencies, dedicated to the identification and monitoring of professional textile products. A reliable architecture for the tag transponder is proposed, featuring a minimal number of galvanic contacts: The two pins of the integrated circuit are connected to the terminals of the inductive coupling loop by using surface mount technology welding. The transponder is encapsulated with an electrically insulating material which is waterproof and resistant to mechanical, thermal, and chemical stress. The antenna is inductively coupled to the transponder through a double loop which substantially reduces the length of the tag and significantly improves the coupling factor, enabling the tag to operate at a low power level. The reliability and flexibility of the tag is obtained by using appropriate materials and manufacturing methods for the ultra-high frequency (UHF) antenna by embroidering a multifilament stainless steel wire on textile support. The washing cycle tests have validated the applicability of this flexible and washable RFID tag, and its electromagnetic performance was experimentally assessed in an independent laboratory.

Control Conflict Suppressing and Stability Improving for an MMC Distributed Control System

Compared with traditional centralized control strategies, the distributed control systems significantly improve the flexibility and expandability of an modular multilevel converter (MMC). However, the stability issue in the MMC distributed control system with the presence of control loop coupling interactions is rarely discussed in existing research works. This article is to improve the stability of an MMC distributed control system by inhibiting the control conflict due to the coupling interactions among control loops with incomplete control information. By modeling the MMC distributed control system, the control loop coupling interactions are analyzed and the essential cause of control conflict is revealed. Accordingly, a control parameter design principle is proposed to effectively suppress the disturbances from the targeted control conflict and improve the MMC system stability. The rationality of the theoretical analysis and the effectiveness of the control parameter design principle are confirmed by simulation and experimental results.

A weak microwave detection method based on resonator noise suppression technology

We put forward a simple method to test extremely weak microwaves by a self-made near field microwave detection system, which is made up of a λ/4 tunable resonance cavity and tungsten tip. By increasing the number of cycles of coupling loops, the technical problem of impedance matching is solved, and the background noise is suppressed. Hence, we can obtain a good sensitivity and spatial resolution of microwave power testing. In this way, the gigahertz electromagnetic wave is loaded to the tip-sample system efficiently, and the thermal parameter measurement of a chip with picowatt level can be obtained by non-contact scanning mode.

Polarity effect of PD in oil-pressboard insulation under highly uneven electric field

The polarity effect of the partial discharge (PD) in oil-pressboard (oil-PB) insulation under a highly non-uniform electric field is remarkable. For intensive analysis of the characteristics and mechanisms of this polarity effect, a non-uniform electric field was simulated by a needle-plate model with oil-PB composite insulation. The PD statistical features, PD pattern and PD pulse were studied via pulse current method, the charge distribution was simulated on the basis of hydrodynamic drift-diffusion model and bipolar charge transport model, and the cause of the polarity effect was analysed based on the PD mechanism which is quantificationally explained via a PD circuit model. It was found that the average apparent discharge amplitude and PD repetition rate of the neg-PD are higher; the average equivalent frequency and equivalent time of neg-PD are higher and lower respectively; the pos-PD pulse is unimodal and the neg-PD pulse is oscillating with some secondary discharges at AC voltage or a back discharge at DC voltage; and the neg-PD pulse has a narrower width owning to the fast rising edge and falling edge. The PD current pulse in the coupling loop is essentially caused by the charging process of the streamer-shorted defect. The cause of the polarity effect is that the positive streamer evolves slowly and can puncture the entire oil gap with an energy-concentrated channel, whereas the negative streamer with a diffused channel evolves faster but cannot puncture the entire oil gap.

Impedance Modeling and Analysis for DFIG-Based Wind Farm in SSO Studies

Several models were developed in the literatures for studying the system impedance characteristics during sub-synchronous oscillations (SSO). However, the doubly-fed induction generator (DFIG) impedance presents a 2 × 2 matrix with the frequency coupling component at the off-diagonal position, which increases the difficulty for analyzing the impedance characteristics of DFIG. The coupling effect in this case is caused by the asymmetric impedance characteristics of controllers, which are composed of voltage source converters (VSCs). Accordingly, simplifications are often conducted to decouple the impedance matrix into single sequences. Outer loop controller and phase-locked loop (PLL), which are often neglected in simplifications, are the main causes of the asymmetry of impedance matrix. Such simplifications could also hamper proper system stability analyses. In this paper, a comprehensive impedance model is proposed in which the outer loop controller, PLL, and grid-side controller (GSC) are all considered. The proposed comprehensive impedance model can provide exact stability data, in which stable boundaries for compensation level and transmission distances are presented. Furthermore, the proposed model is converted to simplified models in which the impacts of outer loop controller, PLL, GSC and coupling components on boundary stability of SSO are analyzed. The results are validated by time domain simulations and eigenvalue analyses, and deviations of the simplified models are analyzed for different operating parameters and conditions leading to simplifications.

Deconstructing Hunting Behavior Reveals a Tightly Coupled Stimulus-Response Loop

Animal behavior often forms sequences, built from simple stereotyped actions and shaped by environmental cues. A comprehensive characterization of the interplay between an animal's movements and its environment is necessary to understand the sensorimotor transformations performed by the brain. Here, we use unsupervised methods to study behavioral sequences in zebrafish larvae. We generate a map of swim bouts, revealing that fish modulate their tail movements along a continuum. During prey capture, larvae produce stereotyped sequences using a subset of bouts from a broader behavioral repertoire. These sequences exhibit low-order transition dynamics and immediately respond to changes in visual cues. Chaining of prey capture bouts is disrupted in visually impaired (lakritz and blumenkohl) mutants, and removing the prey stimulus during ongoing behavior in closed-loop virtual reality causes larvae to immediately abort the hunting sequence. These results suggest that the continuous integration of sensory information is necessary to structure the behavior. This stimulus-response loop serves to bring prey into the anterior dorsal visual field of the larvae. Fish then release a capture strike maneuver comprising a stereotyped jaw movement and tail movements fine-tuned to the distance of the prey. Fish with only one intact eye fail to correctly position the prey in the strike zone, but are able to produce the strike itself. Our analysis shows that short-term integration of binocular visual cues shapes the behavioral dynamics of hunting, thus uncovering the temporal organization of a goal-directed behavior in a vertebrate.

Compact Stripline Dual-Band Bandpass Filters With Controllable Frequency Ratio and High Selectivity Based on Self-Coupled Resonator

Dual-band stripline bandpass filters (BPFs) with widely controllable frequency ratio and high selectivity is proposed based on a new type of self-coupled resonator. The presented self-coupled resonator evolves from a symmetrical open-ended stepped-impedance resonator (SIR) by folding their two open-ended arms coupled with each other. Due to different capacitance characteristics under even- and odd-mode operation in coupled-line, the two fundamental resonant frequencies of self-coupled SIR bring out dual passbands that can be separated in a wider spacing than the ones generated by noncoupled resonator. In addition, due to the inherent coupling loop, two additional transmission zeros (TZs) are generated in the middle stopband between dual passbands, which greatly improves the isolation between dual passbands. For design guidance, theoretical responses are provided with numerical solutions of each resonant frequency and TZ. For demonstrative purposes, two filters with dual passbands centered at 1 and 4 GHz (frequency ratio of 4:1), as well as 2 and 3 GHz (frequency ratio of 1.5:1) are designed, fabricated and tested. In our designs, edge-coupled striplines are used for the final implementation attributing to its good performances of no frequency dispersion in wideband and easy package. Ultimately, experimental results are displayed to convincingly verify the feasibility of proposed concept.

A U-shaped microwave resonator for flexible mechanical sensors application.

A flexible mechanical deformation test system, which is a combination of the microwave and the flexible film, is proposed. The system consists of a U-shaped microwave resonator, coaxial transmission line, and PDMS flexible substrate. Microwave signals are generated from the vector network analyzer and loaded to the coaxial transmission line and then coupled to the U-shaped resonator through the coupling loop. The resonator works at the gigahertz band with the test range from 3 GHz to 40 GHz. The resonant frequency of the resonator can be adjusted by changing the shape of PDMS, and the related signals can be detected by using the S11 parameter of the microwave. The response time of the U-shaped resonator is less than 20 ms, and the sensitivity on the curved surface is 12.5 Hz/nm.

Bounds on CP-violating Higgs-gluon interactions: the case of vanishing light-quark Yukawa couplings

We investigate CP-violating interactions involving the Higgs boson and gluons within an effective field theory approach, focusing on the specific class of new-physics scenarios where the Yukawa couplings of light quarks are zero or strongly suppressed compared to the standard-model expectations. We compute the contributions of the most relevant higher-dimensional operators of Weinberg type to the electric dipole moment of the neutron (nEDM), which are induced by Feynman diagrams that involve an effective CP-violating Higgs-gluon coupling and top-quark loops. The resulting nEDM sensitivities and prospects are discussed and compared to the existing and expected LHC bounds. We find that future nEDM searches can set non-trivial constraints on CP-violating Higgs-gluon interactions even if the Higgs only couples to the third generation of quarks.

Dynamic characteristics analysis of the hydro-hybrid liquid Sodium lubricated bearing-rotor coupled system in the two-circuit main loop liquid sodium pump system

The research explores rotor dynamics characteristics and dynamic responses of Sodium bearing rotor coupled system fast reactor two-circuit main loop liquid sodium pump system in the nuclear power station. Natural frequency and vibration modes are given, vibration amplitude at the key point of support position are extracted. Through the analysis, rotor-dynamic properties and performances of the rotor system are given. With regard to different operating and initial conditions, the rotor-dynamic characteristics are investigated. Extreme operation conditions are also analyzed. Analysis shows that the structure design of sodium bearing as well as the bearing-rotor coupled system are reasonable and reliable, which can fully meet the technical requirements. Results indicate that it has certain guidance for the design of special engineering bearing-rotor system.

A Power Quality Improved EV Charger With Bridgeless Cuk Converter

An improved bridgeless (BL) Cuk converter-based electric vehicle (EV) battery charger with high power factor and increased efficiency is designed and developed in this paper. It provides low cost and high-power-density-based charging solution for the EV. This charger incorporates less number of devices operating over one switching cycle, which reduces the additional conduction loss incurred by a diode bridge rectifier of the conventional charger. Hence, it improves the charger's efficiency. The added advantage of the proposed topology is that the unwanted capacitive coupling loop is removed, as well as the unwanted conduction through the body diode of the inactive switch in the previously developed BL Cuk converter is avoided. This significantly improves the charger's efficiency. For the constant current and constant voltage charging, the commands are synchronized by a flyback converter. The proposed charger draws a sinusoidal current from ac mains and the total harmonic distortion in the supply current is reduced to the limits specified by the IEC 61000-3-2 guidelines. The improved efficiency and power quality indices of the proposed charger are investigated to demonstrate its satisfactory charging operation at all operating conditions.

Increased Risk of Musculoskeletal Injury Following Sport-Related Concussion: A Perception-Action Coupling Approach.

Recent studies have concluded that athletes have increased risk of musculoskeletal injury following sport-related concussion. While an underlying explanation is still unknown, perceptual-motor control may be implicated in this increased risk. Some authors have purported that indirect perception (i.e., a "top-down" view of neuromuscular control) may be disrupted following sport-related concussion. Direct perception theory states that the athlete and environment are inextricably linked in a continuous perception-action coupling loop. That is, the athlete is able to directly perceive opportunities for action (e.g., "affordances") in the environment. Based on these notions, the aim of the current paper was to introduce a theoretical model that argues that sport-related concussion may dysregulate the direct perception process, potentially increasing behavioral risk of musculoskeletal injury during sport. Our model is integrated with a sport-related concussion clinical treatment model, which highlights individualized profiles that characterize the heterogeneous response to sport-related concussion. These profiles have a typical constellation of symptoms (e.g., anxiety, fatigue, ocular dysfunction, etc.), which themselves have been associated with disrupted perception-action coupling, independent of sport-related concussion. Therefore, we argue that athletes who have not re-established perception-action coupling loops following sport-related concussion may be at increased risk of subsequent musculoskeletal injury.

1-D semi-analytical modeling and parametric study of a single phase rectangular Coupled Natural Circulation Loop

The study of heat exchangers with both the hot and cold fluid sides driven by buoyancy forces is an area of considerable interest due to their inherent passivity and non-existence of moving parts. The current study aims to study such heat exchange devices employing the basic Coupled Natural Circulation Loop (CNCL) systems. A one dimensional (1-D) Fourier series based semi-analytical model of the basic CNCL system is proposed. A 3-D CFD validation is performed to validate the developed 1-D model. The non-dimensional numbers such as Grashof number, Fourier number, Stanton number and Reynolds number, which determine the system behavior are identified and a detailed parametric study is performed. Both vertical and horizontal CNCL systems are considered along with the parallel and counter flow configurations. The heater-cooler location greatly influences the behavior of CNCL system. The vertical CNCL always exhibits counter flow configuration whereas the horizontal CNCL system may exhibit parallel or counter flow arrangement depending on the heater-cooler location and initial flow conditions.