Increase In Number Of Channels Research Articles

Large-scale parameters framework with large convolutional kernel for encoding visual fMRI activity information.

Visual encoding models often use deep neural networks to describe the brain's visual cortex response to external stimuli. Inspired by biological findings, researchers found that large receptive fields built with large convolutional kernels improve convolutional encoding model performance. Inspired by scaling laws in recent years, this article investigates the performance of large convolutional kernel encoding models on larger parameter scales. This paper proposes a large-scale parameters framework with a sizeable convolutional kernel for encoding visual functional magnetic resonance imaging activity information. The proposed framework consists of three parts: First, the stimulus image feature extraction module is constructed using a large-kernel convolutional network while increasing channel numbers to expand the parameter size of the framework. Second, enlarging the input data during the training stage through the multi-subject fusion module to accommodate the increase in parameters. Third, the voxel mapping module maps from stimulus image features to functional magnetic resonance imaging signals. Compared to sizeable convolutional kernel visual encoding networks with base parameter scale, our visual encoding framework improves by approximately 7% on the Natural Scenes Dataset, the dedicated dataset for the Algonauts 2023 Challenge. We further analyze that our encoding framework made a trade-off between encoding performance and trainability. This paper confirms that expanding parameters in visual coding can bring performance improvements.

Numerical study on thermal performance of cold plates with leaf type channels for lithium-ion batteries

PurposeThe purpose of this study is to design a new type of cold plate to improve the thermal performance of liquid-cooled thermal management system of lithium-ion batteries.Design/methodology/approachA cold plate with leaf type channels is proposed to enhance the cooling performance. Effects of the leaf type channel parameters (i.e. channel angle 20°, 40°, 60°, 80°; coolant mass flow rate 0.25 × 10–3, 0.50 × 10–3, 0.75 × 10–3, 1.00 × 10–3, 1.25 × 10–3 kg·s−1; channel number 1, 3, 5, 7) on the performance are numerically investigated by using a 3D mathematical model.FindingsCompared to the traditional I type channels, the leaf type channels have better cooling performance. It is found that the battery temperature variation and channel pressure drop are decreased with decreasing channel angle and increasing channel number. In addition, the cooling performance can be improved by increasing the coolant mass flow rate.Practical implicationsThis study can provide guidance for the development of novel effective cold plates.Originality/valueThe design of cold plates with leaf type channels can be used in liquid-cooled thermal management system to reduce the battery temperature difference.

Pore-scale investigation on porous media morphology evolution considering dissolution and precipitation

Mineral dissolution and precipitation are commonly encountered in geologic CO2 injection. In this study, a novel method DLA-QSGS coupling diffusion limited aggregation (DLA) and quartet structure generation set (QSGS) is proposed to generate random distribution of mineral components and fluid. As an example of application, the reactive transport process is then numerically studied with various pore morphology using the lattice Boltzmann method at pore-scale. An insoluble mineral component and soluble mineral components that involve simple and complex reactions for dissolution and precipitation are considered. The impact of mirror morphology, channel width and sub-channels on solid volume evolution and hydrogen ion concentration are investigated. The temperature field is affected by the channel width and sub-channel number. The results suggest that the technique increasing channel numbers is more effective than that increasing channel width during CO2 fracturing.

Tau isoform-specific enhancement of L-type calcium current and augmentation of afterhyperpolarization in rat hippocampal neurons

Accumulation of tau is observed in dementia, with human tau displaying 6 isoforms grouped by whether they display either 3 or 4 C-terminal repeat domains (3R or 4R) and exhibit no (0N), one (1N) or two (2N) N terminal repeats. Overexpression of 4R0N-tau in rat hippocampal slices enhanced the L-type calcium (Ca2+) current-dependent components of the medium and slow afterhyperpolarizations (AHPs). Overexpression of both 4R0N-tau and 4R2N-tau augmented CaV1.2-mediated L-type currents when expressed in tsA-201 cells, an effect not observed with the third 4R isoform, 4R1N-tau. Current enhancement was only observed when the pore-forming subunit was co-expressed with CaVβ3 and not CaVβ2a subunits. Non-stationary noise analysis indicated that enhanced Ca2+ channel current arose from a larger number of functional channels. 4R0N-tau and CaVβ3 were found to be physically associated by co-immunoprecipitation. In contrast, the 4R1N-tau isoform that did not augment expressed macroscopic L-type Ca2+ current exhibited greatly reduced binding to CaVβ3. These data suggest that physical association between tau and the CaVβ3 subunit stabilises functional L-type channels in the membrane, increasing channel number and Ca2+ influx. Enhancing the Ca2+-dependent component of AHPs would produce cognitive impairment that underlie those seen in the early phases of tauopathies.

Development of an integrated multichannel inlet for improved particle classification in hydrocyclones

The inlet design of hydrocyclones determines the flow field symmetry and facilitates the formation of vortices. In this study, an integrated multichannel inlet based on the Archimedes spiral is developed to improve particle classification by combining the advantages of existing designs. Hydrocyclones with conventional tangent or novel spiral inlets are comparably studied to evaluate the feasibility and superiority of this design using the validated volume of fraction model and two-fluid model. Numerical results show that this novel spiral inlet dramatically improves the flow field symmetry in terms of radial velocity and air core as well as reduces the short-circuit flow and circulation flow. In addition, it also provides strong diversion and pre-separation effects on particles. Consequently, this novel spiral inlet provides superior classification performance than the conventional design, appearing in smaller cut-size, higher cut sharpness, and higher capacity. Such advantages become less evident with increasing channel number, due to the increased turbulence intensity caused by the additional feed streams. The spiral inlet with two channels can largely resemble the design with two tangential inlets in all indices, which makes it the most suitable in this study. This design method can be easily extended to other types of hydrocyclones.

Four Decades of Advances from MSDP to S4I and SLED Imaging Spectrometers

The Multichannel Subtractive Double Pass (MSDP) is an imaging spectroscopy technique, which allows observations of spectral line profiles over a 2D field of view with high spatial and temporal resolution. It has been intensively used since 1977 on various spectrographs (Meudon, Pic du Midi, the German Vacuum Tower Telescope, THEMIS, Wroc{\l}aw). We summarize previous developments and describe the capabilities of a new design that has been developed at Meudon and that has higher spectral resolution and increased channel number: Spectral Sampling with Slicer for Solar Instrumentation (S4I), which can be combined with a new and fast polarimetry analysis. This new generation MSDP technique is well adapted to large telescopes. Also presented are the goals of a derived compact version of the instrument, the Solar Line Emission Dopplerometer (SLED), dedicated to dynamic studies of coronal loops observed in the forbidden iron lines, and prominences. It is designed for observing total solar eclipses, and for deployment on the Wroc{\l}aw and Lomnicky peak coronagraphs respectively for prominence and coronal observations.

Improved weighting scheme using consumer-level GNSS L5/E5a/B2a pseudorange measurements in the urban area

The accurate global navigation satellite system (GNSS) positioning in the dense urban areas is still a challenge, especially for low-cost receivers. The multipath effects and non-line-of-sight (NLOS) receptions from surrounding buildings will significantly degrade the positioning performance. Due to the increasing channel number in GNSS chip, the low-cost receiver tends to be capable of acquiring multi-frequency signals, including the new L5-band signal. Because of the higher chipping rate, the GNSS L5-band measurement is less affected by the multipath effect, whereas the measurement number is limited in the current stage. On the contrary, the availability of the conventional L1-band measurement is sufficient to achieve a good dilution of precision (DOP). Based on the complementary characteristics, a GNSS L1/L5 bands integrated positioning algorithm is developed in this study to improve the positioning performance in urban areas. A modified weighting model based on carrier-to-noise ratio and satellite elevation angle is employed to assign proper weighting between L1-band and L5-band measurements. Meanwhile, the dMP5 feature from dual-frequency measurement and the consistency check algorithm are employed to detect and exclude outliers, which are possibly NLOS receptions. Experimental results and analyses indicate that the developed DFE-CCWLS method can significantly improve the positioning accuracy, achieving the root-mean-square error less than 10 m for most of the urban scenarios.

Self-Heating Induced Interchannel Vt Difference of Vertically Stacked Si Nanosheet Gate-All-Around MOSFETs

The natural asymmetry of the vertically stacked channels results in the junction temperature difference in nanosheet channels which is dependent on pitch, nanosheet width, channel number, and input power. The Vt difference induced by the self-heating becomes worse with the process imperfections, such as the interface trap density. PFET has higher Vt difference due to the higher thermal resistance and stronger temperature dependence of Vt than nFET (22mV vs 6.5mV for 15nm pitch, 35nm nanosheet width, 3 channels, and DC input). The Vt difference increases with the increasing channel number and nanosheet width.

Enhanced activity of multiple TRIC-B channels: an endoplasmic reticulum/sarcoplasmic reticulum mechanism to boost counterion currents.

Key points There are two subtypes of trimeric intracellular cation (TRIC) channels but their distinct single‐channel properties and physiological regulation have not been characterized. We examined the differences in function between native skeletal muscle sarcoplasmic reticulum (SR) K+‐channels from wild‐type (WT) mice (where TRIC‐A is the principal subtype) and from Tric‐a knockout (KO) mice that only express TRIC‐B.We find that lone SR K+‐channels from Tric‐a KO mice have a lower open probability and gate more frequently in subconducting states than channels from WT mice but, unlike channels from WT mice, multiple channels gate with high open probability with a more than six‐fold increase in activity when four channels are present in the bilayer.No evidence was found for a direct gating interaction between ryanodine receptor and SR K+‐channels in Tric‐a KO SR, suggesting that TRIC‐B–TRIC‐B interactions are highly specific and may be important for meeting counterion requirements during excitation–contraction coupling in tissues where TRIC‐A is sparse or absent. The trimeric intracellular cation channels, TRIC‐A and TRIC‐B, represent two subtypes of sarcoplasmic reticulum (SR) K+‐channel but their individual functional roles are unknown. We therefore compared the biophysical properties of SR K+‐channels derived from the skeletal muscle of wild‐type (WT) or Tric‐a knockout (KO) mice. Because TRIC‐A is the major TRIC‐subtype in skeletal muscle, WT SR will predominantly contain TRIC‐A channels, whereas Tric‐a KO SR will only contain TRIC‐B channels. When lone SR K+‐channels were incorporated into bilayers, the open probability (Po) of channels from Tric‐a KO mice was markedly lower than that of channels from WT mice; gating was characterized by shorter opening bursts and more frequent brief subconductance openings. However, unlike channels from WT mice, the Po of SR K+‐channels from Tric‐a KO mice increased as increasing channel numbers were present in the bilayer, driving the channels into long sojourns in the fully open state. When co‐incorporated into bilayers, ryanodine receptor channels did not directly affect the gating of SR K+‐channels, nor did the presence or absence of SR K+‐channels influence ryanodine receptor activity. We suggest that because of high expression levels in striated muscle, TRIC‐A produces most of the counterion flux required during excitation‐contraction coupling. TRIC‐B, in contrast, is sparsely expressed in most cells and, although lone TRIC‐B channels exhibit low Po, the high Po levels reached by multiple TRIC‐B channels may provide a compensatory mechanism to rapidly restore K+ gradients and charge differences across the SR of tissues containing few TRIC‐A channels.

Research on Bandwidth Limit of Multi - channel Signal Splicing

Multi-channel narrowband signal through the splicing to synthesis a single channel wideband signal is an effective way to expand the signal bandwidth. At present, the multi-channel signal bandwidth splicing is basically achieved, and the error in splicing process has also been in-depth analysis. However, the bandwidth of the signal obtained by splicing the multi-channel signal has yet to be analyzed and demonstrated. In this paper, according to the principle of multi-channel signal splicing, the bandwidth limit of multi-channel signal splicing is analyzed theoretically. Secondly, the upper limit bandwidth of multi-channel signal splicing is analyzed from the engineering realization of multi-channel signal splicing. From the analysis results, the bandwidth of multi-channel signal splicing can be extended with the increase of channel number and single-channel signal bandwidth. In the engineering realization, the signal bandwidth of splicing can only be effectively expanded in RF splicing, while it will be limited by the clock frequency of mixer.

Hadamard transform-based calibration method for programmable optical filters based on digital micro-mirror device.

Digital micromirror device (DMD) based optical filters provide a new avenue for spectral modulation in many research applications. Traditional sequential channel scanning method for the calibration of such filters may suffer from compromised spectral tuning accuracy due to the signal to noise ratio restriction on the minimum pixel number of each channel. In this work, we propose a Hadamard transform based calibration method to address this issue. A DMD-based programmable optical filter is constructed and calibrated using both the sequential scanning method and the proposed method for the subsequent synthesis of three representative filters (i.e., the bandpass filter, Gaussian filter, and principal component based filter). The spectral tuning accuracy is evaluated by calculating the relative root mean square error (RMSE) between the synthesized transmittance spectrum and the target spectrum. The results show that when calibrated with the proposed method, the programmable filter exhibits a consistent decrease in the relative RMSE with an increasing channel number for all filters. The smallest relative RMSE values are therefore achieved when each channel contains only one DMD pixel. In contrast, for the sequential scanning method, the relative RMSE increases dramatically when each channel contains three or fewer DMD pixels. This suggests that our method is superior to the sequential scanning method in spectral tuning accuracy when the signal level is low.

SRS VE FWM OLAYLARININ DWDM-GPON SİSTEMLERİN AŞAĞI YÖNLÜ KANAL PERFORMANSLARI ÜZERİNDEKİ BİRLEŞİK ETKİSİ

In this paper the combined impact of stimulated Raman scattering (SRS) and four-wave mixing (FWM) on the downlink channel performance of dense wavelength division multiplexed-gigabit passive optical networks (DWDM-GPONs) has been compared with the single impact of FWM via signal-to-crosstalk ratio (SXR) simulations performed on center downlink channels of 7-, 15- and 31-channel DWDM-GPON systems. Simulation results show that SRS compensates negative impacts of FWM and compensation significance enhances with increasing channel numbers and channel spacing values. At high channel spacing values of 50 GHz and 100 GHz, variation of SXR can display a strong oscillatory behavior in very short channel length variations of 0.5 km. The combined impact of SRS and FWM enhances the maximum oscillation amplitude of SXR variation with respect to the single impact of FWM at those channel spacing values. It has been observed that Raman gain exhibits an approximately linear variation with channel input powers in 0.1-5 mW range and it increases with increasing fiber lengths, channel spacing values and channel numbers. Results of this research emphasize the significant difference between the combined impact of SRS and FWM and the single impact of FWM on DWDM-GPON systems and give important hints for current DWDM-GPON implementations.

Numerical simulation study of the heat transfer characteristic in Ω-shape grooved heat pipes

Heat pipes are devices capable of very high heat transfer and have been widely used in many thermal management applications. An experimental investigation and CFD simulation of thermal characteristics of heat pipe was presented in the present work. It can be found that using FLUENT can simulate the evaporation and condensation in heat pipe. With the increase of chamber diameter, the equivalent thermal conductivity and maximum heat transfer capacity of heat pipe are both on an increasing trend, however, the thermal resistance reduces gradually. With the increase of channel number, the thermal resistance and maximum heat transfer capacity of heat pipe are both on an increasing trend, however, the equivalent thermal conductivity reduces gradually. Results in the present work can provide guidance to further research of grooved heat pipe.

A Novel Planar Waveguide Super-Multiple-Channel Optical Power Splitter

In this paper, we have proposed a novel planar waveguide optical-power-splitter design with a large number of splitting channels. The design uses the wavefront lateral interference in light propagation in a slab waveguide, with its core properly adjusted in different areas for achieving different effective indices for the required phase delays. Therefore, the whole structure is equivalent to a nonblocking all-pass filter, hence, suffers a very small insertion loss. Another unique advantage of this structure lies in its weak length dependence on the number of splitting channels; although its lateral size has to be scaled up as the channel number increases, as opposed to conventional splitters with both of its length and lateral size scaled up with increasing channel numbers. Our numerical simulation results show that, for a 1-to-256 channel splitter within a working wavelength band from 1530 to 1570 nm, the insertion loss is below 1.3 dB. The channel nonuniformity is less than 5 dB within the same band. The required size is within 2.5 mm by 10 mm on the silicon-on-insulator platform. The proposed structure can readily be extended to other material platforms, such as the silica-based planar lightwave circuit or semiconductors. Its fabrication process is fully compatible with standard clean-room technologies, such as photolithography and etching, without any complicated and/or costly approach involved.

Numerical Comparison of WDM Interchannel Crosstalk in FOPA- and PPLN-Based PSAs

We propose a model and numerical simulations to calculate crosstalk (XT) between multiple wavelength-division-multiplexing (WDM) channels in copier + phase sensitive amplifier (PSA) chains based on periodically poled lithium niobate (PPLN). The calculated XT is compared with XT generated in copier + PSA chains based on highly nonlinear fiber (HNLF). For ordinary device parameters, the results show that for an increasing channel number, the growth of interchannel XT in PPLN is less rapid compared with HNLF, as a consequence of the finite quasi-phase matching band of PPLN. This ensures lower XT in PPLN-based chains for 18 channels, whereas HNLF chains show better XT performance for 4 channels.

Investigation on Flow Maldistribution in Parallel Microchannel Systems for Integrated Microelectronic Device Cooling

This paper brings out the phenomenon of flow maldistribution in parallel microchannel systems, which is supposed to have an adverse effect on hot spot formation and temperature distribution in microelectronic devices. An extensive experimental study is carried out where in the parameters affecting the flow maldistribution such as number of channel, area of cross section of the manifold, channel hydraulic diameter, and Reynolds number are varied to study their effect on the pressure drop across the parallel channels designed for liquid cooling of a CPU. It is observed that the flow distribution among the channels improves significantly with a decrease in the channel hydraulic diameter due to higher pressure drop offered by each individual channels simultaneously. This results in a considerable reduction in both the peak temperature and the average temperature of the device with decreasing channel diameters. It is also inferred that the flow maldistribution is relatively invariant with Reynolds number for the microchannel system, which is not the case for the macrochannels. Flow maldistribution is found to increase with increase in number of channels and with a decrease in the manifold area relative to the channel area. The “I” type flow configuration is found to have the least maldistribution while the “U” type shows the maximum and Z type falls in between. A simple force analysis of the governing equation in the manifold of the parallel microchannel system reveals a strong dominance of the frictional force over the inertial force and both the forces contribute to the uniform flow distribution at smaller hydraulic diameters, where the 1-D theoretical models failed to achieve a concurrence with the present experimental results. Also the present 3-D numerical simulations give a satisfactory agreement with the experimental results projecting it as an effective tool in the design and analysis of microchannel cooling system. The potential zones of hot spots are identified as low fluid velocity zones or low pressure drop zones among the channels resulting from flow maldistribution.

Voltage dependence of the Ca2+-activated K+ channel KCa3.1 in human erythroleukemia cells

We have isolated a K(+)-selective, Ca(2+)-dependent whole cell current and single-channel correlate in the human erythroleukemia (HEL) cell line. The whole cell current was inhibited by the intermediate-conductance KCa3.1 inhibitors clotrimazole, TRAM-34, and charybdotoxin, unaffected by the small-conductance KCa2 family inhibitor apamin and the large-conductance KCa1.1 inhibitors paxilline and iberiotoxin, and augmented by NS309. The single-channel correlate of the whole cell current was blocked by TRAM-34 and clotrimazole, insensitive to paxilline, and augmented by NS309 and had a single-channel conductance in physiological K(+) gradients of ~9 pS. RT-PCR revealed that the KCa3.1 gene, but not the KCa1.1 gene, was expressed in HEL cells. The KCa3.1 current, isolated in HEL cells under whole cell patch-clamp conditions, displayed an activated current component during depolarizing voltage steps from hyperpolarized holding potentials and tail currents upon repolarization, consistent with voltage-dependent modulation. This activated current increased with increasing voltage steps above -40 mV and was sensitive to inhibition by clotrimazole, TRAM-34, and charybdotoxin and insensitive to apamin, paxilline, and iberiotoxin. In single-channel experiments, depolarization resulted in an increase in open channel probability (Po) of KCa3.1, with no increase in channel number. The voltage modulation of Po was an increasing monotonic function of voltage. In the absence of elevated Ca(2+), voltage was ineffective at inducing channel activity in whole cell and single-channel experiments. These data indicate that KCa3.1 in HEL cells displays a unique form of voltage dependence modulating Po.

Performance evaluation of mesh-based NoCs: Implementation of a new architecture and routing algorithm

This paper presents the result of experiments conducted in mesh networks on different routing algorithms, traffic generation schemes and switching schemes. A new network on chip (NoC) topology based on partial interconnection of mesh network is proposed and a routing algorithm supporting the proposed architecture is developed. The proposed architecture is similar to standard mesh networks, where four extra bidirectional channels are added which remove the congestion and hotspots compared to standard mesh networks with fewer channels. Significant improvement in delay (60% reduction) and throughput (60% increase) was observed using the proposed network and routing when compared with the ideal mesh networks. An increase in number of channels makes the switches expensive and could increase the area and power consumption. However, the proposed network can be useful in high speed applications with some compromise on area and power.

A hybrid method for more efficient channel‐by‐channel reconstruction with many channels

In MRI, imaging using receiving coil arrays with a large number of elements is an area of growing interest. With increasing channel numbers for parallel acquisition, longer reconstruction times have become a significant concern. Channel reduction techniques have been proposed to reduce the processing time of channel-by-channel reconstruction algorithms. In this article, two schemes are combined to enable faster and more accurate reconstruction than existing channel reduction techniques. One scheme use two stages of channel reduction instead of one. The other scheme is to incorporate all acquired data into the final reconstruction. The combination of these two schemes is called flexible virtual coil. Applications of flexible virtual coil for partially parallel imaging, motion compensation, and compressed sensing are presented as specific examples. Theoretical analysis and experimental results demonstrate that the proposed method has a major impact in reducing computation cost in reconstruction with high-channel count coil elements.

On the end-to-end flow allocation and channel assignment in multi-channel multi-radio wireless mesh networks with partially overlapped channels

The performance of wireless mesh networks (WMNs) can be improved significantly with the increase in number of channels and radios. Despite the availability of multiple channels in several of the current wireless standards, only a small fraction of them are non-overlapping and many channels are partially overlapped. In this paper, we formulate the joint channel assignment and flow allocation problem for multi-channel multi-radio WMNs as a Mixed Integer Linear Program (MILP). Unlike most of the previous studies, we consider the case when both non-overlapped and partially overlapped channels are being used. We consider an objective of maximizing aggregate end-to-end throughput and minimizing queueing delay in the network, instead of the sum of link capacities, since the traffic characteristics of a multi-hop WMN are quite different from a single hop wireless network. Our static channel assignment algorithm incorporates network traffic information, i.e., it is load aware. Our formulation takes into consideration several important network parameters such as the transmission power of each node, path loss information, the signal to interference plus noise ratio at a node, and the frequency response of the filters used in the transmitter and receiver. We show by simulations that our MILP formulation makes efficient use of the spectrum, by providing superior channel assignments and flow allocations with the addition of partially overlapped channels, without the use of any additional spectrum. We also justify the need to consider alternative objective functions such as, minimizing average queueing in the network. We also propose a polynomially bounded heuristic algorithm to scale the proposed algorithm to bigger network topologies.