Number Of Channels Research Articles

Design and experimental research of orbital angular momentum multiplexing holography based on optical diffraction neural network.

The orbital angular momentum (OAM) multiplexing holography has the advantages of large information capacity and high security, and has important application value in holographic storage, optical encryption, and optical computing. However, as the number of multiplexing channels increases, this technology suffers from deterioration in image quality, which limits its application scope. This article proposes an innovative design that introduces an optical diffractive neural network (ODNN) into OAM multiplexing holography, establishes a scientific image quality evaluation function, applies an end-to-end optimization method, and designs OAM multiplexing holograms in parallel, significantly improving the image quality of OAM holography. The design results show that compared to classical methods, the ODNN method proposed in this paper has improved diffraction efficiency and signal-to-noise ratio by 29% and 19%, respectively, and reduced mean square error and variance by 10% and 43%, respectively. Moreover, high-quality multi-channel OAM multiplexing holography has been achieved through experiments. The design method proposed in this article provides an efficient and practical way for future OAM multiplexing holographic technology to further enhance information capacity and improve security.

Decoupling of Phase and Amplitude Channels with a Terahertz Metasurface Toward High‐Security Image Hiding

AbstractSteganography technology which conceals a message in a carrier to make it invisible is critical for information security. Conventional optical image steganography using diffractive optical components or spatial light modulators suffers from less encoding channel and bulky volume. The emergence of multifunctional metasurface that can manipulate abundant physical dimensions of optical fields allows the multi‐channel image steganography in a compact volume. Here, the image hiding in a metasurface is demonstrated by modulating the amplitude, phase, and polarization states of terahertz (THz) waves completely. Especially, the phase channel can decouple from the amplitude channel based on a Fresnel‐diffraction‐based algorithm. By directly measuring the phase distribution using the homemade THz focal plane imaging system, the number of transmission channels can expand from N to 2N. As a proof of concept, it is shown that the secret images can encode in the phase channel and subsequently extract by using different keys, such as polarization states, detection distances, and its combinations. Moreover, different hiding strategies with different attacker behaviors are also demonstrated. The decoupling of the phase and amplitude channels with a single metasurface may open an avenue toward innovative optoelectronic devices for optical image steganography, data storage, and terahertz communication.

MicroRNA maintains nutrient homeostasis in the symbiont-host interaction.

Endosymbionts provide essential nutrients for hosts, promoting growth, development, and reproduction. However, the molecular regulation of nutrient transport from endosymbiont to host is not well understood. Here, we used bioinformatic analysis, RNA-Sequencing, luciferase assays, RNA immunoprecipitation, and in situ hybridization to show that a bacteriocyte-distributed MRP4 gene (multidrug resistance-associated protein 4) is negatively regulated by a host (aphid)-specific microRNA (miR-3024). Targeted metabolomics, microbiome analysis, vitamin B6 (VB6) supplements, 3D modeling/molecular docking, in vitro binding assays (voltage clamp recording and microscale thermophoresis), and functional complementation of Escherichia coli were jointly used to show that the miR-3024/MRP4 axis controls endosymbiont (Serratia)-produced VB6 transport to the host. The supplementation of miR-3024 increased the mortality of aphids, but partial rescue was achieved by providing an external source of VB6. The use of miR-3024 as part of a sustainable aphid pest-control strategy was evaluated by safety assessments in nontarget organisms (pollinators, predators, and entomopathogenic fungi) using virus-induced gene silencing assays and the expression of miR-3024 in transgenic tobacco. The supplementation of miR-3024 suppresses MRP4 expression, restricting the number of membrane channels, inhibiting VB6 transport, and ultimately killing the host. Under aphids facing stress conditions, the endosymbiont titer is decreased, and the VB6 production is also down-regulated, while the aphid's autonomous inhibition of miR-3024 enhances the expression of MRP4 and then increases the VB6 transport which finally ensures the VB6 homeostasis. The results confirm that miR-3024 regulates nutrient transport in the endosymbiont-host system and is a suitable target for sustainable pest control.

Design of an on-chip integrated multi-channel comb filter based on the Bragg grating structure.

We designed a multi-channel comb filter generation scheme with nearly consistent channel numbers and free spectral range (FSR) in standard 220-nm-thick silicon-on-insulator (SOI) technology. This scheme relies on the formation of optical microcavities using Bragg grating structures, which serve as reflectors. By precisely designing the optical path length of the microcavity, we can generate optical filters with a specific number of channels. Using this scheme, we developed and tested three devices to implement two-channel, three-channel, and four-channel comb filters, with FSRs of approximately 5.5 nm, 4 nm, and 3.3 nm, respectively. As an application, this three-channel filter can be used to implement a temperature sensor with a high temperature sensitivity of about 53 pm/K. The proposed multi-channel comb filter provides a novel, to the best of our knowledge, scheme to utilize Bragg gratings, offering a new perspective for future densely integrated silicon photonics.

Comparison of oxidation resistance of high-entropy (Ti0.2Zr0.2Hf0.2Ta0.2Nb0.2)C/SiC composites prepared by different methods at 1300–1600 °C

Dense monolithic (Ti0.2Zr0.2Hf0.2Ta0.2Nb0.2)C/SiC (HEC/SiC) composites were prepared via single-source-precursor (SSP) and solid-state reaction (SSR) method, respectively. The SSP-method nanocomposite features HEC nanoparticles uniformly dispersed within β-SiC, while the SSR-method composite is a microcomposite containing micro-sized HEC and β-SiC particles. The oxidation tests at 1300–1600 ºC show that the HEC/SiC nanocomposites exhibit much better oxidation resistance than that of the HEC/SiC microcomposites. Firstly, the generated metal-containing complex oxides ((Zr,Hf)6Ta2O17, Ti(Ta,Nb)2O7, and Ta-doped rutile TiO2) become more facile for sintering due to the nano-scaled HEC phase. Secondly, the cracks resulting from the oxidation of HEC nanoparticles are fewer and smaller, decreasing the number of channels for oxygen to pass through and channels need to be healed by SiO2. Finally, the homogeneous distribution of the HEC nanoparticles within β-SiC ensures the homogeneity of the complex oxide layer, significantly reducing the cracks caused by volume expansion and preventing the oxide layer from peeling off.

Experimental study on thermal–hydraulic performance of a nature-inspired mini-channel heat exchanger manufactured by 3D printing

Zigzag-channel printed circuit heat exchangers (PCHEs) are widely used in nuclear energy, solar energy, and aerospace due to their good heat transfer performance. However, the high flow resistance of zigzag channels leads to large pumping power consumption and thus limits the overall performance. Although previous modified channels could reduce the flow resistance of PCHEs, they also bring a decrease in the heat transfer efficiency. Inspired by river islands, this study proposes a novel nature-inspired channel. The nature-inspired channel heat exchanger, along with a traditional zigzag-channel heat exchanger, were manufactured by 3D printing. The high-temperature air-air flow and heat transfer experiments show that the nature-inspired channel heat exchanger increases the average heat transfer rate by 1.5% and significantly reduces the pressure drop by 34.85%. The addition of airfoil fins at the corners effectively alleviates the flow resistance caused by flow separation, reattachment, and collision, leading to a higher Nusselt number and a lower Fanning friction factor. The Nusselt number of nature-inspired channel is 59% higher than that of the zigzag channel with a 15° inclined angle. This work demonstrates that the nature-inspired channel could significantly reduce the flow resistance while maintaining high heat transfer efficiency compared with the traditional zigzag channel.

Three-dimensional grid-free sound source localization method based on deep learning

Sound source localization (SSL) technology is a popular method for identifying the locations of noise sources, which serves as a prerequisite for noise control. Deep learning, as a data-driven tool, shows broad perspectives in the field of SSL with its powerful nonlinear fitting ability. The existing deep learning-based SSL methods only provide a two-dimensional (2D) representation of the sound source location and cannot obtain the specific coordinates of the sound source in three-dimensional (3D) space. Although traditional beamforming methods can be directly generalized to 3D scenes in principle, they suffer from the limitations of insufficient vertical resolution and high computational cost. Therefore, a 3D grid-free SSL method (3DGF) informed by deep learning is suggested in this study to enhance the accuracy and computational efficiency of 3D localization. First, the number of data channels is compressed to respect limited memory resources during the training process. Subsequently, a dense convolutional neural network (DenseNet) model is utilized to obtain the 3D spatial coordinates of the sound source using the processed 3D beamforming map as input. Since the coordinates are continuous and are not constrained by the grid of the beamforming map, the grid-free strategy presents more accurate localization results. Then, the effects of the volume of training data and the compression ratio are analyzed, respectively, in simulation, and the localization performance with different signal-to-noise ratios (SNRs) is also tested. Finally, by comparing 3DGF with DAMAS, both simulation and experimental results demonstrate that 3DGF improves the accuracy and efficacy of 3D localization. Meanwhile, its satisfactory generalization ability and robustness against noise highlight its potential for practical applications.

Non-uniform optical phased array based on dual-adaption genetic algorithm improved by chaos sequence

To address the issue of diminishing peak side lobe levels (PSLL) in non-uniform optical phased array (OPA) as steering angle increases, we introduce a dual-adaption genetic algorithm (DAGA) based on chaos sequence to optimize the antenna array layout. By leveraging chaos mapping traversal and randomness, this approach enhances the diversity of the initial antenna layout, thereby improving the algorithm's capacity to escape local optima. Concurrently, we also reduce background noise during the array steering process to enhance PSLL at large steering angle. In this study, we optimize non-uniform antenna arrays with 64-, 128-, and 256-channels. The results demonstrate that at a steering angle of 80°, the PSLL is improved by 2.18, 2.81, and 3.59 dB, respectively, compared to the conventional genetic algorithm (GA). Notably, for a 256-channel array, the PSLL can be optimized to an impressive -18.46 dB using this method. To our knowledge, this represents the lowest PSLL achieved for an equivalent number of channels. Our research offers valuable insights for the practical implementation of OPAs as transmitters in chip-scale frequency modulated continuous wave (FMCW) light detection and ranging (LiDAR) systems.

Impact of potential and temperature fluctuations on charge and heat transport in quantum Hall edges in the heat Coulomb blockade regime

We present a broad study of charge and heat transport in a mesoscopic system where one or several quantum Hall edge channels are strongly coupled to a floating Ohmic contact (OC). It is well-known that charge-current fluctuations emanating from the OC along the edge channels are highly susceptible to the OC charge capacitance in the heat Coulomb blockade regime (an impeded ability of the OC to equilibrate edge channels). Here, we demonstrate how potential and temperature fluctuations due to finite OC charge and heat capacities impact the heat-current fluctuations emitted from the OC. First, by assuming an infinite OC heat capacity, we show that the output heat-current noise is strongly dependent on the OC charge capacitance, following from a close relation between one-dimensional charge and heat currents. When also the OC heat capacity is finite, an interplay of potential and temperature fluctuations influences the heat transport. Concretely, we find that the effect of the charge capacitance on heat transport manifests in terms of a strongly increased energy relaxation time in the heat Coulomb blockade regime. Furthermore, we find expressions for a broad set of output observables, such as charge and heat auto- and cross correlations, as functions of input and OC fluctuations, depending on the relation between charge and energy relaxation times compared to the frequency of fluctuations and inverse (local) temperatures as well as on the number of edge channels attached to the OC. Finally, we show that a finite OC heat capacity transforms the full counting statistics of the output charge from Gaussian to non-Gaussian. Our findings provide opportunities to experimentally probe and harness the quantum nature of heat transport in strongly coupled electron circuits. Published by the American Physical Society 2024

Role of physical structure on performance index of crossflow microchannel heat exchanger with regression analysis

Microchannel heat exchangers have become the preferred choice in contemporary technologies like electronics, refrigeration, and thermal management systems. Their popularity stems from their compact design and exceptional efficiency, which outperform traditional heat exchangers (HE). Despite ongoing efforts, the optimal microchannels for enhancing heat management, minimizing pressure drop, and boosting overall performance have yet to be identified. This study seeks to deepen our understanding of heat transmission and fluid dynamics within a cross-flow microchannel heat exchanger (CFMCHE). Utilizing numerical modeling, it examines how various physical aspects—such as channel geometry, spacing between channels, the number of channels, and the velocity at the inlet—affect key performance indicators like pressure drop, effectiveness, Nusselt number, and overall efficiency. To enhance the design, we analyze six unique shapes of crossflow microchannel heat exchangers: circular, hexagonal, trapezoidal, square, triangular, and rectangular. We employ the Galerkin-developed weighted residual finite element method to numerically address the governing three-dimensional conjugate partial differential coupled equations. The numerical results for each shape are presented, focusing on the surface temperature, pressure drop, and temperature contours. Additionally, calculations include the efficacy, the heat transfer rate in relation to pumping power, and the overall performance index. The findings reveal that while circular shapes achieve the highest heat transfer rates, they underperform compared to square-shaped CFMCHEs. This underperformance is largely due to the increased pressure drop in circular channels, which also exhibit a 1.03% greater reduction in effectiveness rate than their square-shaped counterparts. Consequently, square-shaped channels, boasting a performance index growth rate of 53.57%, emerge as the most effective design among the six shapes evaluated. Additionally, for the square-shaped CFMCHE, we include residual error plots and present a multiple-variable linear regression equation that boasts a correlation coefficient of 0.8026.

Generalization of the Synthetic Aperture Radar Azimuth Multi-Aperture Processing Scheme—MAPS

This paper analyzes the advantages and the drawbacks of using the Synthetic Aperture Radar (SAR) azimuth multichannel technique known as Multi-Aperture Processing Scheme (MAPS), in a set of relevant application cases that are far from the canonical ones. In the scientific literature on this topic, equally distributed azimuth channels with the quasi-monostatic deployment are assumed. With this research, we aim at extending the models from the current literature to (i) a generic bistatic acquisition geometry, (ii) a set of cases where the number of receiving tiles is not the same for each channel, or (iii) the tiles are shared between adjacent channels thus creating an overlapping configuration. The paper introduces the mathematical models for the listed non-conventional MAPS cases. Dealing with the bistatic MAPS, we first solve the problem by interpreting multichannel acquisition as a bank of Linear Time Invariant (LTI) filters. Then, a more physical approach, based on discrimination of the direction of arrivals (DoAs) is pursued. The effectiveness of the two methods and the advantages of the second approach on the first are proved by using a simplified 1D end-to-end simulation. Even limiting to the monostatic configuration, the azimuth antenna tiles have always been supposed equally partitioned among the RX channels. Overcoming this limit has two advantages: (i) more MAPS possible solutions in case few azimuth tiles are available, as in the ROSE-L mission; (ii) the number of channels can be designed independently of the number of tiles, also allowing asymmetric solutions, useful for a phase array antenna with an odd number of tiles such as in the SAOCOM-1 mission. Conversely, sharing one or more receiving tiles in different receiving channels makes the input noise partially correlated. The drawback is an increase in the noise level. A trade-off is determined for the different solutions obtained using simulations with real mission parameters. The theoretical performance and the end-to-end simulations are compared.

New readout scheme for large area timing & position RPCs

A new readout technique was developed with the primary aim of keeping the number of channels in the front-end electronics as low as possible when scaling up the sensitive area of a Resistive Plate Chamber (RPC). The readout method here presented significantly reduces the dependence between the detector area and the number of electronic channels, without substantial reduction of its performance: a 30 × 30 cm2 double stack multi-gap timing RPC was operated during weeks with cosmic rays, achieving a 2D spatial resolution well below 1 mm and time resolution lower than 100 ps, while its efficiency was kept above 98%.

Optimization of liquid cooling plate considering coupling effects of heat generation and aging characteristics in power batteries

The heat generation and aging characteristics of power batteries exhibit a strong coupling relationship, and thus designing liquid cooling plates (LCPs) requires considering both aspects to achieve optimal thermal management. In this study, an electric-thermal-aging model (ETAM) correlating internal resistance, capacity, and temperature was developed. Based on this model, the effects of a serpentine LCP on the heat generation and aging characteristics of battery pack under different operating conditions were investigated using a combined simulation of zero-dimensional numerical model and three-dimensional CFD methods. Furthermore, the LCP channel widths in the length and width directions and the number of channels were optimized using orthogonal tests, artificial neural networks, and genetic algorithms, aiming to minimize battery capacity degradation. Results showed that increasing the mass flow rate of the coolant reduced the maximum temperature, temperature difference, capacity loss, and aging inconsistency of the battery pack. Conversely, reducing the coolant inlet temperature could decrease the maximum temperature and capacity loss but increased the temperature difference and aging inconsistency of the battery pack. The orthogonal test results indicated that the number of channels had the greatest impact on the heat generation and aging characteristics of the battery pack, followed by the channel width in the length direction, and the channel width in the width direction had the least impact. After optimization, the maximum temperature of the battery pack decreased by 0.57 %, the maximum temperature difference increased by 1.41 %, and the average capacity degradation decreased by 0.20 %. Moreover, with the increasing mass flow rate, the pressure drop reduction improved from 27.90 % to 33.90 %. This study may provide guidance for the design of LCPs that take battery aging into account.

An efficient and practical electrode optimization method for transcranial electrical stimulation

Transcranial electrical stimulation (TES) is a non-invasive neuromodulation technique with great potential. Electrode optimization methods based on simulation models of individual TES field could provide personalized stimulation parameters according to individual variations in head tissue structure, significantly enhancing the stimulation accuracy of TES. However, the existing electrode optimization methods suffer from prolonged computation times (typically exceeding 1 d) and limitations such as disregarding the restricted number of output channels from the stimulator, further impeding their clinical applicability. Hence, this paper proposes an efficient and practical electrode optimization method. The proposed method simultaneously optimizes both the intensity and focality of TES within the target brain area while constraining the number of electrodes used, and it achieves faster computational speed. Compared to commonly used electrode optimization methods, the proposed method significantly reduces computation time by 85.9% while maintaining optimization effectiveness. Moreover, our method considered the number of available channels for the stimulator to distribute the current across multiple electrodes, further improving the tolerability of TES. The electrode optimization method proposed in this paper has the characteristics of high efficiency and easy operation, potentially providing valuable supporting data and references for the implementation of individualized TES.

Are there 34,000 human emotions? Deconstructing patterns of scientific misinformation

ABSTRACT Background Scientific misinformation is a much-discussed topic, and the COVID-19 crisis has highlighted the importance of reliability in science and research. However, limiting misinformation is complicated because of the growing number of communication channels, in which scientific and nonscientific content are often mixed. Methods This case study combines the examination of references, online observation, and a content and frequency analysis to investigate the dissemination of scientific misinformation in the interplay of different genres and media. Results Using the example of the claimed existence of 34,000 human emotions, this study demonstrates how questionable statements are spread in science, popular science, and pseudoscience, making it particularly challenging to track and correct them. Conclusions The findings highlight epistemic authority, trust, and injustice within and between scientific and nonscientific communities. The author argues that, in the digital age, researchers should defend and monitor scientific principles beyond academia.

A microstrip-based dielectric sensor with four fluidic channels for complex dielectric constant detection of aqueous alcohols

A cost-effective planar microstrip-based dielectric sensor with four fluidic channels on its ground plane is proposed for estimating the concentration and complex dielectric constants of ethanol/water mixtures. The channels are placed on the long sides of the slot resonators, which are slightly carved from the substrate. The sensor prototype is fabricated, showing good agreement between simulated and measured parameters. The sensor's resonance characteristics, influenced by the binary mixtures, are used to estimate the dielectric constants with an empirical relation. Validation is achieved through good correspondence with literature values. The sensor's resonance can be tailored by adjusting the number of fluidic channels. With a normalized sensitivity of 0.063% using 17.28 µl of material-under-test, the sensor is label-free, reusable, non-destructive, contactless, and suitable for lab-on-chip chemical sensing applications.

Performance Analysis of Microwave Photonic Spectral Filters based on Optical Microcombs

AbstractMicrowave transversal filters, which are implemented based on the transversal filter structure in digital signal processing, offer a high reconfigurability for achieving a variety of signal processing functions without changing hardware. When implemented using microwave photonic (MWP) technologies, also known as MWP transversal filters, they provide competitive advantages over their electrical counterparts, such as large operation bandwidth, strong immunity to electromagnetic interference, and low loss when processing signals at high frequencies. Recent advances in high‐performance optical microcombs provide compact and powerful multi‐wavelength sources for MWP transversal filters that require a larger number of wavelength channels to achieve high performance, allowing for the demonstration of a diverse range of filter functions with improved performance and new features. Here, a comprehensive performance analysis for microcomb‐based MWP spectral filters based on the transversal filter approach is presented. First, the theoretical limitations are investigated in the filter spectral response induced by finite tap numbers. Next, the distortions are analyzed in the filter spectral response resulting from experimental error sources. Finally, the influence of input signal's bandwidth on the filtering errors is assessed. These results provide a valuable guide for the design and optimization of microcomb‐based MWP transversal filters for a variety of applications.

Low cross-talk optical addressing of trapped-ion qubits using a novel integrated photonic chip

Individual optical addressing in chains of trapped atomic ions requires the generation of many small, closely spaced beams with low cross-talk. Furthermore, implementing parallel operations necessitates phase, frequency, and amplitude control of each individual beam. Here, we present a scalable method for achieving all of these capabilities using a high-performance integrated photonic chip coupled to a network of optical fibre components. The chip design results in very low cross-talk between neighbouring channels even at the micrometre-scale spacing by implementing a very high refractive index contrast between the channel core and cladding. Furthermore, the photonic chip manufacturing procedure is highly flexible, allowing for the creation of devices with an arbitrary number of channels as well as non-uniform channel spacing at the chip output. We present the system used to integrate the chip within our ion trap apparatus and characterise the performance of the full individual addressing setup using a single trapped ion as a light-field sensor. Our measurements showed intensity cross-talk below ~10–3 across the chip, with minimum observed cross-talk as low as ~10–5.

DECNet: Left Atrial Pulmonary Vein Class Imbalance Classification Network.

In clinical practice, the anatomical classification of pulmonary veins plays a crucial role in the preoperative assessment of atrial fibrillation radiofrequency ablation surgery. Accurate classification of pulmonary vein anatomy assists physicians in selecting appropriate mapping electrodes and avoids causing pulmonary arterial hypertension. Due to the diverse and subtly different anatomical classifications of pulmonary veins, as well as the imbalance in data distribution, deep learning models often exhibit poor expression capability in extracting deep features, leading to misjudgments and affecting classification accuracy. Therefore, in order to solve the problem of unbalanced classification of left atrial pulmonary veins, this paper proposes a network integrating multi-scale feature-enhanced attention and dual-feature extraction classifiers, called DECNet. The multi-scale feature-enhanced attention utilizes multi-scale information to guide the reinforcement of deep features, generating channel weights and spatial weights to enhance the expression capability of deep features. The dual-feature extraction classifier assigns a fixed number of channels to each category, equally evaluating all categories, thus alleviating the learning bias and overfitting caused by data imbalance. By combining the two, the expression capability of deep features is strengthened, achieving accurate classification of left atrial pulmonary vein morphology and providing support for subsequent clinical treatment. The proposed method is evaluated on datasets provided by the People's Hospital of Liaoning Province and the publicly available DermaMNIST dataset, achieving average accuracies of 78.81% and 83.44%, respectively, demonstrating the effectiveness of the proposed approach.

High Spatial Resolution Detector System Based on Reconfigurable Dual-FPGA Approach for Coincidence Measurements.

Time-resolved spectroscopic and electron-ion coincidence techniques are essential to study dynamic processes in materials or chemical compounds. For this type of analysis, it is necessary to have detectors capable of providing, in addition to image-related information, the time of arrival for each individual detected particle ("x, y, time"). The electronics capable of handling such sensors must meet requirements achievable only with time-to-digital converters (TDC) with a resolution on the order of tens of picoseconds and the use of a field-programmable gate array (FPGA) to manage data acquisition and transmission. This study introduces the design and implementation of an innovative TDC based on two FPGAs working symbiotically with different tasks: the first (AMD/Xilinx Artix® 7) directly implements a TDC, aiming for a temporal precision of 12 picoseconds, while the second (Intel Cyclone® 10) manages the acquisition and connectivity with the external world. The TDC has been optimized to operate on eight channels (+ sync) simultaneously but is potentially extendable to a greater number of channels, making it particularly suitable for coincidence measurements where it is necessary to temporally correlate multiple pieces of information from various measurement systems.