Multiple Parallel Channels Research Articles

High-Throughput Microfluidic Particle Counter Based on Optical Absorption.

With the utilization of advanced microfluidic techniques, the microfluidic particle counter demonstrates significant potential due to its high efficiency, precise manipulation, and portability. This work focuses on a photodetection counter based on optical absorption. To achieve precise particle detection, a Christmas tree-like structure was implemented to separate a single particle from a cluster, which was then detected in independent multiple parallel channels. The system exhibits a high degree of reliability, as evidenced by a linear correlation coefficient over 0.99 obtained during testing with gradient-concentrated beads. Furthermore, when the calculated density of NIH 3T3 cells is compared with that of a traditional flow cytometer, the system achieves a substantial agreement percentage ranging from 87.5 to 99.9%. The system's ability to perform high-throughput analysis with a high acquisition rate positions it as a promising tool for real-time point-of-care testing.

Demonstration of a multi-channel fluidized bed particle–supercritical carbon dioxide heat exchanger for concentrating solar applications

High-temperature thermal energy storage in oxide particles at temperatures above 600°C can couple concentrated solar energy with high-efficiency thermal power cycles to provide dispatchable solar-driven electricity. Challenges remain in developing cost-effective primary heat exchangers, which require expensive alloys, to extract the high-temperature thermal energy from the particles to power cycle fluids, such as supercritical CO2 (sCO2) in recuperated Brayton cycles. To explore one pathway for cost-effective, high-temperature particle heat exchangers, the current study demonstrates a shell-and-plate, particle–sCO2 heat exchanger with narrow-channel fluidized beds coupled with micro-channel sCO2 flows in the heat exchanger walls. This study evaluates the feasibility of multiple parallel, narrow-channel fluidized beds in shell-and-plate particle–sCO2 HXs, to achieve high bed-wall heat fluxes at elevated temperatures. A reduced-order model simulates the narrow-channel, fluidized-bed particle–sCO2 heat exchanger to design the fluidized bed geometry, in terms of depth, height, and number of channels,for a nominal 40-kWth heat exchanger at particle and sCO2 inlet temperatures up to 600°C and 400°C respectively. The resulting shell-and-plate heat exchanger design operates with bubbling fluidization of the downward-flowing oxide particles to enhance bed-wall heat transfer. The heat exchanger core is fabricated with etched sCO2 micro-channels in thin wall plates that are diffusion bonded to spacer frames to form the shell-and-plate structure with 12 parallel, fluidized bed channels, 10.4 mm deep. The heat exchanger is tested at the National Solar Thermal Test Facility at Sandia National Laboratories with CARBOBEAD HSP particles at design particle flow rates of 0.20 kg s−1 and inlet temperatures up to 525°C. Results show that fluidization across multiple parallel channel beds can maintain uniform particle inventory with a common freeboard zone above the heat exchanger core. Bubbling fluidization improves particle–wall heat transfer coefficients but also increases axial dispersion of particle thermal energy, which lowers the log-mean temperature difference such that total heat transfer remains relatively constant to within ±10% over a broad range of fluidization gas velocities. The axial dispersion required particle and sCO2 flow rates to be increased by 25% over model-designed conditions to achieve the targeted 40 kWth, which indicates the importance of incorporating axial dispersion into heat exchanger design models and of deploying bed structures to suppress it. This study demonstrates the feasibility and preferred fluidizing gas conditions for particle heat exchangers for releasing high-temperature thermal energy storage systems.

CheckShake: Passively Detecting Anomaly in Wi-Fi Security Handshake Using Gradient Boosting Based Ensemble Learning

Recently, a number of attacks have been demonstrated (like key reinstallation attack, called KRACK) on WPA2 protocol suite in Wi-Fi WLAN, for which a patching is often challenging. In this paper, we design and implement a system, called CheckShake, to passively detect anomalies in the handshake of Wi-Fi security protocols, in particular WPA2, between a client and an AP using COTS radios. Our proposed system works without decrypting any traffic and sniffing on multiple channels in parallel. It uses a state machine model for grouping Wi-Fi handshake packets and then perform deep packet inspection to identify the symptoms of the anomaly in specific stages of a handshake session. Our implementation of CheckShake does not require any modification to the firmware of the client or the AP or the COTS devices, it only requires to be physically placed within the range of the AP and its clients. We use both the publicly available dataset and our own data set for performance analysis of CheckShake. Using gradient boosting-based supervised machine learning (ML) models, we show that an accuracy around 98.50% with no false positive can be achieved using CheckShake in open sourced data that has non-zero probability of missing packets per group of packets.

Replacement of the native cis prolines by alanine leads to simplification of the complex folding mechanism of a small globular protein

The folding mechanism of MNEI, a single-chain variant of naturally occurring double-chain monellin, is complex, with multiple parallel refolding channels. To determine whether its folding energy landscape could be simplified, the two native cis-prolines, Pro41 and Pro93, were mutated, singly and together, to Ala. The stability of P93A was the same as that of the wild-type protein, pWT; however, P41A and P41AP93A were destabilized by ∼0.9 kcal mol−1. The effects of the mutations on the very fast, fast, slow, and very slow phases of folding were studied. They showed that heterogeneity in the unfolded state arises due to cis to trans isomerization of the Gly92-Pro93 peptide bond. The Pro41 to Ala mutation abolished the very slow phase of folding, whereas surprisingly, the Pro93 to Ala mutation abolished the very fast phase of folding. Double-jump, interrupted folding experiments indicated that two sequential trans to cis proline isomerization steps, of the Gly92-Pro93 peptide bond followed by the Arg40-Pro41 peptide bond, lead to the formation of the native state. They also revealed the accumulation of a late native-like intermediate, N∗, which differs from the native state in the isomeric status of the Arg40-Pro41 bond, as well as in a few tertiary contacts as monitored by near-UV CD measurements. The Pro to Ala mutations not only eliminated the cis to trans Pro isomerization reaction in the unfolded state, but also the two trans to cis Pro isomerization reactions during folding. By doing so, and by differentially affecting the relative stabilities of folding intermediates, the mutations resulted in a simplification of the folding mechanism. The two Pro to Ala mutations together accelerate folding to such an extent that the native state forms more than 1000-fold faster than in the case of pWT.

A low-complexity algorithm based on variational Bayesian inference for MIMO channel estimation

With an increase in the number of transmitters in multiple-input multiple-output (MIMO) communication systems, there is a cubic rise in the computational complexity of the traditional sparse Bayesian learning (SBL) channel estimation algorithm. While various algorithms are effective for single-input single-output (SISO) systems, they are not suitable for the MIMO scenario. This paper introduces a MIMO channel estimation algorithm based on variational Bayesian inference (VBI) by assuming the independence of the variational distribution among different channels. The high-dimensional channel vectors estimated in the conventional MIMO-SBL algorithm are decomposed into multiple parallel low-dimensional channel vectors with different sparsity using VBI. Consequently, the complexity exhibits a linear relationship with the number of transmitters, as demonstrated through numerical analysis. Simulations confirm the improved estimation accuracy of the MIMO-VBI algorithm. Experimental results reveal that MIMO systems can achieve lower bit error rates using the MIMO-VBI algorithm, with reduced runtime for channel lengths exceeding 100 symbols.

Experimental investigation and analysis of two-phase flow instability of flow boiling in a mini-channel heat sink

High heat flux and good axial temperature uniformity of channel flow boiling demonstrate that it is ideally suited for next-generation cooling systems. Such systems, however, are hampered by undesirable flow fluctuations, making channel flow boiling ineffective due to the rapid bubble growth within the channels. Furthermore, especially in the mini-channel heat sink, the interactions between multiple parallel channels and inlet/outlet plenum induce complex hydraulic and thermal oscillations. Therefore, lots of consistent and detailed experimental data are still needed to design a reliable flow boiling system. However, only limited studies have examined the effects of channel interaction on flow boiling instability. Thus, to provide a better understanding of the flow boiling instabilities, a mini-channel heat sink was tested with near-saturated inlet conditions using FC-72 as the working fluid. The mini-channel heat sink consisted of a 150 mm long and 70.4 mm wide base area, having 22 identical rectangular channels measuring 1.6 × 4.8 mm2. The flow instabilities were analyzed by observing the vapor backflow and flow fluctuation in mini-channels with variations in the mass velocity, pressure, and heat fluxes. The analysis is based on the detailed flow visualization in the parallel channels and inlet plenum. It was found that the rapid bubble generation in individual channels promotes vapor backflow and hydraulic oscillations. Further observation of the high-speed camera images shows that the vapor crossing over between parallel channels through the inlet plenum led to the synchronization of vapor oscillations, which is responsible for the parallel channel flow instability. This visualization study revealed six dominant flow patterns showing multi-channel flow instability. Based on the classification of dominant flow patterns, a better understanding of the operating conditions for stable flow boiling was obtained.

A perspective on the doping of transition metal dichalcogenides for ultra-scaled transistors: Challenges and opportunities

To support the ever-growing demand for faster, energy-efficient computation, more aggressive scaling of the transistor is required. Two-dimensional (2D) transition metal dichalcogenides (TMDs), with their ultra-thin body, excellent electrostatic gate control, and absence of surface dangling bonds, allow for extreme scaling of the channel region without compromising the mobility. New device geometries, such as stacked nanosheets with multiple parallel channels for carrier flow, can facilitate higher drive currents to enable ultra-fast switches, and TMDs are an ideal candidate for that type of next generation front-end-of-line field effect transistor (FET). TMDs are also promising for monolithic 3D (M3D) integrated back-end-of-line FETs due to their ability to be grown at low temperature and with less regard to lattice matching through van der Waals (vdW) epitaxy. To achieve TMD FETs with superior performance, two important challenges must be addressed: (1) complementary n- and p-type FETs with small and reliable threshold voltages are required for the reduction of dynamic and static power consumption per logic operation, and (2) contact resistance must be reduced significantly. We present here the underlying strengths and weaknesses of the wide variety of methods under investigation to provide scalable, stable, and controllable doping. It is our Perspective that of all the available doping methods, substitutional doping offers the ultimate solution for TMD-based transistors.

On Multiple Parallel Channels with a Finite Source

On Multiple Parallel Channels with a Finite Source

Design and fused deposition modeling of triply periodic minimal surface scaffolds with channels and hydrogel for breast reconstruction.

3D-printed scaffolds that forge a new path for regenerative medicine are widely used in breast reconstruction due to their personalized shape and adjustable mechanical properties. However, the elastic modulus of present breast scaffolds is significantly higher than that of native breast tissue, leading to insufficient stimulation for cell differentiation and tissue formation. In addition, the lack of a tissue-like environment results in breast scaffolds being difficult to promote cell growth. This paper presents a geometrically new scaffold, featuring a triply periodic minimal surface (TPMS) that ensures structural stability and multiple parallel channels that can modulate elastic modulus as required. The geometrical parameters for TPMS and parallel channels were optimized to obtain ideal elastic modulus and permeability through numerical simulations. The topologically optimized scaffold integrated with two types of structures was then fabricated using fused deposition modeling. Finally, the poly (ethylene glycol) diacrylate/gelatin methacrylate hydrogel loaded with human adipose-derived stem cells was incorporated into the scaffold by perfusion and ultraviolet curing for improvement of the cell growth environment. Compressive experiments were also performed to verify the mechanical performance of the scaffold, demonstrating high structural stability, appropriate tissue-like elastic modulus (0.2 - 0.83 MPa), and rebound capability (80% of the original height). In addition, the scaffold exhibited a wide energy absorption window, offering reliable load buffering capability. The biocompatibility was also confirmed by cell live/dead staining assay.

High-resolution MRI to noninvasively characterize drainage around the carotid artery into the cervical lymph nodes.

Previous studies have proposed multiple parallel channels for waste clearance from the brain, though many gaps remain in our understanding of these systems. In this study, we examined periarterial fluid drainage around intracranial and extracranial segments of the internal carotid arteries (ICAs) from the brain into the cervical lymph nodes using a noninvasive and clinical-based method. Eighty-one subjects (45 females, aged 15-80years old) with nonlesioned epilepsy underwent high-resolution 3-dimensional T2-weighted fluid-attenuated inversion recovery (FLAIR) MRI. We utilized a noninvasive and clinical-based method with a manual semiautomated approach to characterize the periarterial lymphatic system's maximum thickness and signal intensities along the ICAs using high-resolution 3-dimensional FLAIR imaging. We conducted group comparisons and correlation analyses to investigate sex- and age-based trends. Results were corrected with Bonferroni's test for multiple comparisons, and we performed power analysis for sample size calculations. Using high-resolution FLAIR images, we show evidence that fluid drainage emerges around the ICA petrous segment and joins lymphatic flow from cranial nerves in the upper neck, with this flow ultimately draining into the cervical lymph nodes bilaterally. Lymphatic signal at the petrous segment level was significantly thinner in females compared to males bilaterally (w=413, p=.0001 on the right, w=356, p<.0001 on the left). Lymphatic drainage around the petrous segments of the ICAs bilaterally was thicker with age in males but not in females. We describe the in vivo high-resolution imaging characteristics of periarterial fluid drainage along the vessel walls of ICAs. This represents a potentially major channel for brain waste clearance. We also report interesting sex- and age-based trends in these structures within our cohort.

Scaling microfluidic throughput with flow-balanced manifolds to simply control devices with multiple inlets and outlets.

Microfluidics can bring unique functionalities to cell processing, but the small channel dimensions often limit the throughput for cell processing that prevents scaling necessary for key applications. While processing throughput can be improved by increasing cell concentration or flow rate, an excessive number or velocity of cells can result in device failure. Designing parallel channels can linearly increase the throughput by channel number, but for microfluidic devices with multiple inlets and outlets, the design of the channel architecture with parallel channels can result in intractable numbers of inlets and outlets. We demonstrate an approach to use multiple parallel channels for complex microfluidic designs that uses a second manifold layer to connect three inlets and five outlets per channel in a manner that balances flow properties through each channel. The flow balancing in the individual microfluidic channels was accomplished through a combination of analytical and finite element analysis modeling. Volumetric flow and cell flow velocity were measured in each multiplexed channel to validate these models. We demonstrate eight-channel operation of a label-free mechanical separation device that retains the accuracy of a single channel separation. Using the parallelized device and a model biomechanical cell system for sorting of cells based on their viability, we processed over 16 × 106 cells total over three replicates at a rate of 5.3 × 106 cells per hour. Thus, parallelization of complex microfluidics with a flow-balanced manifold system can enable higher throughput processing with the same number of inlet and outlet channels to control.

A Novel Widely Linear Quaternion Multiband-Structured Subband Adaptive Filter Algorithm

A novel widely-linear quaternion multibandstructured subband adaptive filter (WL-QMSAF) algorithm is proposed for further enhancing the convergence rate of estimation error when input signals are greatly correlated in the quaternion domain. Using the derivative rule in GHR-calculus, the WLQMSAF algorithm is developed on the basis of the principle of minimum fluctuations. The proposed WL-QMSAF algorithm decomposes the input signal into multiple parallel channels to promote more effective signal processing. Since quaternion widely linear model is able to describe complete second-order statistics of input signal, the proposed algorithm can effectively process both Q-proper and Q-improper signals. In addition, the analysis of mean-square steady state for the WL-QMSAF algorithm is performed according to the principle of energy conservation. Finally, numerical simulations are conducted on circular data as well as noncircular data to support the steady-state analysis of mean-square error as well as validate the effectiveness of the proposed WL-QMSAF algorithm.

Block Switching: A Stochastic Approach for Deep Learning Security

Recent study of adversarial attacks has revealed the vulnerability of modern deep learning models. That is, subtly crafted perturbations of the input can make a trained network with high accuracy and produce arbitrary incorrect predictions, while maintaining imperceptible to human vision system. In this paper, we introduce Block Switching (BS), a defense strategy against adversarial attacks based on stochasticity. BS replaces a block of model layers with multiple parallel channels, and the active channel is randomly assigned in the run time, hence unpredictable to the adversary. We show empirically that BS leads to a more dispersed input gradient distribution and superior defense effectiveness compared with other stochastic defenses such as stochastic activation pruning. Compared to other defenses, BS is also characterized by the following features: (i) BS causes less test accuracy drop; (ii) BS is attack-independent; and (iii) BS is compatible with other defenses and can be used jointly with others.

Dynamic Bandwidth allocation algorithm for avoiding Frame rearrangement in NG-EPON

Next Generation Ethernet Passive Optical Network (NG-EPON) is considered to be future prospective access technology that could help to achieve 100Gbps data rates. Wavelength bonding is a phenomenon that can help Optical Network Units (ONU) to enhance their transmission capabilities. Using wavelength bonding, an ONU could transmit on multiple wavelength channels in parallel. The ONUs can achieve data transmission rates ranging from 25Gbps to 100Gbps. In upstream direction, ONUs share different available channels in time-sharing manner to effectively utilize the resources in NG-EPON. Dynamic Wavelength & Bandwidth Allocation (DWBA) algorithm is required for efficient allocation of wavelength and bandwidth resources in upstream direction. DWBA plays a vital role to help ONUs for transmission on multiple channels simultaneously. When an ONU transmits on multiple channels, a frame-rearrangement problem would occur at the Optical Line Terminal (OLT). OLT suffers from an extra overhead of frame-rearrangement; as the received frames at OLT are not in proper sequence. DWBA can play a vital role in avoiding frame rearrangement overhead. We proposed a DWBA algorithm to avoid/minimize frame rearrangement problem and efficient bandwidth allocation in NG-EPON. Our proposed DWBA avoids and minimizes frame-rearrangement problem and provides efficient resource allocation. We comparatively analyzed and evaluated our proposed DWBA with the existing DWBA algorithm. The simulation results show that our proposed DWBA minimizes frame-rearrangement problem as compared to existing DWBA algorithms and proves to be more efficient based on average (end-to-end) delay and completion time.

VLSI Implementation of Multi-Channel ECG Lossless Compression System

Electrocardiogram (ECG) is used to record the electrical activity of heart. If the instrument monitoring the signal for a long time, it will produce large amount of data. So, the effective lossless ECG compression system can help to reduce the storage space. This brief presents a hardware architecture of multi-channel lossless ECG compression system. The system is based on the algorithm including multi-channel linear prediction and adaptive linear prediction. Also, Golomb rice code (GRC) is used for entropy coding. The hardware implementation has been designed with low hardware complexity usage while using optimum hardware resources. And the architecture can process multiple channels in parallel that can obtain the high throughput. PTB database has been used for verification and testing purposes. This design was implemented in TSMC 180nm. The implementation results show the gate count is 476K and power consumption is 69.18μW while working frequency is 1 KHz.

Multi-channel AlGaN/GaN Schottky barrier diodes with a half through-hole

The cutoff frequency of Schottky barrier diode (SBD) depends on its junction capacitance and series resistance. The two-dimensional electron gas (2DEG) at AlGaN/GaN interface has high carrier mobility and carrier concentration. However, AlGaN/GaN heterostructure SBD usually shows a high series resistance because of the thin 2DEG channel. In this work, multiple AlGaN/GaN heterojunctions are vertically stacked for forming multiple parallel 2DEG channels to reduce the series resistance. Multi-channel AlGaN/GaN-based air-bridge structure planar SBDs with a half through-hole are demonstrated. The series resistance of quintuple-channel SBD is only 39.5% of the single-channel SBD's. Moreover, a low capacitance is obtained by the Schottky electrode with a half through-hole structure. The low series resistance and the low capacitance contribute to a 16 GHz cutoff frequency in millimeter-wave band.

Značaj digitalizacije nabavke u ostvarivanju višekanalne maloprodajne izvrsnosti

Digitalization of procurement is a path to e-procurement and includes a set of practices and technologies, which through smart use of data, ICT and automation, raises the efficiency and effectiveness of existing and leads to the development of new procurement processes and activities. The most common notion of digitalization of procurement in retail implies the implementation of certain electronic solutions in various e-procurement phases of the retailer. Procurement and selling are two sides of the same retail coin. From time immemorial, business logic has dictated that everything should be procured rationally and that only what can be sold should be procured. With the modernization of retail come new challenges, which require exceptional coordination between sales and purchasing activities. Therefore, in certain circumstances, the digitization of sales may affect the digitization of procurement, and vice versa. The concept of multiple channel sales has been extensively present, from the moment when retailers started using multiple marketing channels in parallel. In this regard, modern, theoretically narrower understanding of multiple channel business implies the intersection of physical and digital sales channels. The market implications of the COVID-19 pandemic only further accentuated the need to integrate traditional and electronic sales channels, in order to respond to contactless purchasing requests. Achieving a multiple channel strategy is usually multi-iterative, as the retailer goes through the previous multiple channel phases, gradually expanding the range of sales channels and their integration. In this regard, Jocevski et al. (2019) noted that the key predispositions for the transition from a multichannel to an omnichannel strategy are a "seamless" shopping experience, data integration, and effective supply chain management. By its nature, the digitalization of retail procurement, as a business process, touches on all three key aspects of multiple channel integration. It is in this context that it is necessary to look for the previously mentioned link between the digitization of procurement and sales. Therefore, the focus of this paper will be on locating and explaining the specific ways in which procurement digitalization can affect the multiple channel integration of retail business.

Study of existing designs of the peristaltic principle pumps

Peristaltic pumps are used in a wide variety of applications due to their tightness, ease of maintenance and accurate delivery. Nevertheless, the use of peristaltic pumps is limited by their disadvantages: short service life of the working body and uneven feed. This work provides an overview of the existing design solutions for pumps. The main advantages and disadvantages of the most common modern designs of peristaltic pumps are considered. The developed design solutions are presented. These solutions are designed to extend the service life of the elastic working body of the pump. These include a spiral hose design, where hose life is improved by reducing the number of cyclic compressions using just one roller. Another solution is to operate the pump with incomplete compression of the working element, which reduces the stress values and thereby prolongs the service life of the working element. The special shapes of protrusions in the compression area were developed in order to compensate the decrease in flow caused by the operation of the pump with incomplete compression of the working member. The paper provides an overview of solutions to reduce the uneven flow of a peristaltic pump. The simplest of these is the use of multiple parallel channels. In other designs, the elimination of flow pulsations is achieved with a pneumatic damper. There is also a constructive solution, in which a special algorithm of actuation of five squeeze elements is used for uniform supply, each of which compresses only its own section of the pump working body. Based on the analysis, it is shown that in order to eliminate the disadvantages of peristaltic pumps the various methods are used. Nevertheless, those methods need further improvement.

A New Multichannel Parallel Network Framework for the Special Structure of Multilead ECG.

Electrocardiogram (ECG) contains the rhythmic features of continuous heartbeat and morphological features of ECG waveforms and varies among different diseases. Based on ECG signal features, we propose a combination of multiple neural networks, the multichannel parallel neural network (MLCNN-BiLSTM), to explore feature information contained in ECG. The MLCNN channel is used in extracting the morphological features of ECG waveforms. Compared with traditional convolutional neural network (CNN), the MLCNN can accurately extract strong relevant information on multilead ECG while ignoring irrelevant information. It is suitable for the special structures of multilead ECG. The Bidirectional Long Short-Term Memory (BiLSTM) channel is used in extracting the rhythmic features of ECG continuous heartbeat. Finally, by initializing the core threshold parameters and using the backpropagation algorithm to update automatically, the weighted fusion of the temporal-spatial features extracted from multiple channels in parallel is used in exploring the sensitivity of different cardiovascular diseases to morphological and rhythmic features. Experimental results show that the accuracy rate of multiple cardiovascular diseases is 87.81%, sensitivity is 86.00%, and specificity is 87.76%. We proposed the MLCNN-BiLSTM neural network that can be used as the first-round screening tool for clinical diagnosis of ECG.

Dynamical properties of densely packed confined hard-sphere fluids.

Numerical solutions of the mode-coupling theory (MCT) equations for a hard-sphere fluid confined between two parallel hard walls are elaborated. The governing equations feature multiple parallel relaxation channels which significantly complicate their numerical integration. We investigate the intermediate scattering functions and the susceptibility spectra close to structural arrest and compare to an asymptotic analysis of the MCT equations. We corroborate that the data converge in the β-scaling regime to two asymptotic power laws, viz. the critical decay and the von Schweidler law. The numerical results reveal a nonmonotonic dependence of the power-law exponents on the slab width and a nontrivial kink in the low-frequency susceptibility spectra. We also find qualitative agreement of these theoretical results to event-driven molecular dynamics simulations of polydisperse hard-sphere systems. In particular, the nontrivial dependence of the dynamical properties on the slab width is well reproduced.