Typical Channel Research Articles

Study on the Preparation and Test of Hydrodynamic Focusing Microfluidic Chip Fabricated by Liquid Crystal Display Mask Photo-Curing Method

Microfluidic chips with the function of hydrodynamic focusing is widely used in the field of cell electroporation, droplet formation, drug screening and particle enrichment. Due to the small channel size of microfluidic chip, the existing processing methods have the defects of high fabrication cost or low dimensional consistency, the drawback is particularly prominent at small fabrication quantity. In this study, hydrodynamic focusing microfluidic chip was successfully fabricated by Liquid Crystal Display (LCD) mask photo-curing method with high efficiency and precision, the mechanism of curing parameters on the accuracy of microstructure was investigated, the hot pressing process was proposed to realize the bonding of cured photosensitive resin and glass substrate. By analyzing the focusing width of typical cross structure channel, a hydrodynamic focusing chip was designed. The effects of exposure time and single layer thickness on whole curing time was studied, the factors affecting the surface roughness were investigated, and the dimensional accuracy control method was proposed. The effect of bonding pressure on cured resin temperature was calculated and tested. The focusing width was verified by theoretical calculation and experiment. The mechanism for the inconsistency between the experimental focusing width and the theoretical focusing width was analyzed. The research proposed a solution of microfluidic design, fabrication, bonding and testing, which could provide a theoretical and methodological support for the efficient fabrication of microfluidic chips.

Model and algorithm for vessel scheduling optimisation through the compound channel with the consideration of tide height

To optimise vessel scheduling passing a compound channel with the water depth influenced by the periodic tide, this study establishes the vessel scheduling model through a typical tidal compound channel. In addition, based on the actual tidal data of the channel, a tide height computation function varying with time is obtained. Then a designed genetic algorithm (GA) is utilised to verify the model by the actual vessels' data through the Tianjin Port Fairway. The test experiment shows that the organisation efficiency is better than other methods, including larger draft vessels first (LDF), first come first served (FCFS), random scheduling (RS) and manual scheduling. It can take full advantage of the high tide and improve the vessel scheduling efficiency of a compound channel. With minor alterations, the proposed model and designed algorithm can also serve for vessel traffic organisation in other compound channels affected by tide water as well.

Morphological consequences of upstream water and sediment changes and estuarine engineering activities in Pearl River Estuary channels over the last 50 years

The relative contributions of decreased upstream sediment loads and local estuarine engineering activities to the estuarine channel geometry are poorly understood. In this study, we analyze the hydrological changes and identify the location, duration and intensity of the estuarine engineering activities based on the channel morphologic changes from 1965 to 2017 at the five stations in the Pearl River Estuary. Thereafter, the Mann-Kendall (M-K) statistical test, empirical orthogonal function (EOF) tests, and channel geometry reconstruction based on the hydrological coefficient were performed to quantitatively estimate the relative contributions from upstream dam construction and estuarine engineering activities. The results show that the geometric changes in the five transects over the last 50 years could be divided into three stages. Stage I extends over approximately 23–33 years at the different channel transects, during which the channel geometries were mainly influenced by natural factors, with a balance between erosion and deposition. Stage II occurred during the next 11–20 years and the changes in the cumulated water depth in comparison to the values in the previous adjacent years at this stage are approximately 5–25 times the values in stage I. The human activities (e.g., sand excavation) contribute to >70–90% of the extreme geometric changes. Stage III lasted for <3–11 years in the different transects with a slight depositional trend, and policies regulating sand excavation were implemented during this stage.The rapid increase in the channel area and water depth caused by sand excavation can cause the downcutting of the riverbed, a decrease in the water level, and redistribution of the water and sediment discharge. Therefore, the monitoring, simulation and analysis of the variation in the typical channel geometry over the long term provide important means to understand the human activities occurring and insights for future sustainable estuarine management.

Electrical and Reliability Characteristics of FinFETs With High-k Gate Stack and Plasma Treatments

Due to its agile maneuverability, unmanned aerial vehicles (UAVs) have shown great promise for ondemand communications. In practice, UAV-aided aerial base stations are not separate. Instead, they rely on existing satellites/terrestrial systems for spectrum sharing and efficient backhaul. In this case, how to coordinate satellites, UAVs and terrestrial systems is still an open issue. In this paper, we deploy UAVs for coverage enhancement of a hybrid satellite-terrestrial maritime communication network. Under the typical composite channel model including both large-scale and small-scale fading, the UAV trajectory and in-flight transmit power are jointly optimized, subject to constraints on UAV kinematics, tolerable interference, backhaul, and the total energy of UAV for communications. Different from existing studies, only the location-dependent large-scale channel state information (CSI) is assumed available, because it is difficult to obtain the small-scale CSI before takeoff in practice, and the ship positions can be obtained via the dedicated maritime Automatic Identification System. The optimization problem is non-convex. We solve it by problem decomposition, successive convex optimization and bisection searching tools. Simulation results demonstrate that the UAV fits well with existing satellite and terrestrial systems, using the proposed optimization framework.

RETRACTED ARTICLE: Optimized Fuzzy System Dependent Trust Score for Mobile AdHoc Network

Mobile Ad-Hoc Network (MANET) consist a numerous nodes and these nodes are structured with remote transceivers. These nodes forward the message with one another by getting to the typical channel. In MANET, security is the principle challenge to be analyzed. Due to the behaviour of malevolent nodes, the network security is weakened. Along these lines, the significant goal of this research is to enhance the network security by detecting the malevolent nodes. So, for the detection of malevolent node, an effective trust management method is presented in this paper. Improving the trust score the optimized fuzzy framework is proposed. For enhancing the execution of the fuzzy framework, the triangular membership function of the input parameters is improved with the Cat Swarm Optimization. After estimating the trust score for every node in the network, threshold depend decision module is processed for detecting the activity of malevolent nodes. Implementation results illustrate that the execution of the proposed model achieves maximum network lifetime and minimum energy consumption.

Optimizing Volumetric Efficiency and Backscatter Communication in Biosensing Ultrasonic Implants.

Ultrasonic backscatter communication has gained popularity in recent years with the advent of deep-tissue sub-mm scale biosensing implants in which piezoceramic (piezo) resonators are used as acoustic antennas. Miniaturization is a key design goal for such implants to reduce tissue displacement and enable minimally invasive implantation techniques. Here, we provide a systematic design approach for the implant piezo geometry and operation frequency to minimize the overall volume of the implant. Optimal geometry of the implant piezo for backscatter communication is discussed and contrasted with that of power harvesting. A critical design aspect of an ultrasonic backscatter communication link is the response of the piezo acoustic reflection coefficient Γ with respect to the variable shunt impedance, ZE, of the implant uplink modulator. Due to the complexity of the piezo governing equations and multi-domain, electro-acoustical nature of the piezo, Γ(ZE) has often been characterized numerically and the implant uplink modulator has been designed empirically resulting in sub-optimal performance in terms of data rate and linearity. Here, we present a SPICE friendly end-to-end equivalent circuit model of the channel as a piezo-IC co-simulation tool that incorporates inherent path losses present in a typical ultrasonic backscatter channel. To provide further insight into the channel response, we present experimentally validated closed form expressions for Γ(ZE) under various boundary conditions. These expressions couple Γ to the commonly used Thevenin equivalent circuit model of the piezo, facilitating systematic design and synthesis of ultrasonic backscatter uplink modulators.

Investigation on the Water Flow Evolution in a Filled Fracture under Seepage-Induced Erosion

Water inrush is a major geological hazard for safe mining and tunnel construction. For the water inrush channel containing mud, sand, and other sediments, it is difficult to predict the change of permeability and water surge, which makes disaster prevention difficult. As a typical water inrush channel, a filled fracture under seepage-induced erosion needs to be focused. In this work, a numerical model for the evolution of flow in a filled fracture under seepage-induced erosion was established, which included the seepage velocity, hydraulic erosion, and permeability of the filling medium. The effects of joint roughness coefficient (JRC) and homogeneity of the filling medium on the seepage evolution are discussed. The results showed that the fracture seepage properties experienced a non-linear change process, and the evolution can be divided into three phases: the slowly varying phase, the rapidly varying phase, and the stable phase. The increase of the JRC hindered the development in flow velocity and erosion. Compared with low homogeneous filling medium, pores in the high homogeneous filling medium were easier to expand and connect, and the seepage characteristics evolved faster. The model established in this study will help to understand the seepage evolution of filled fractures, and can be used to predict the permeability of filled fractures in engineering geology.

An analysis of the influences of groundwater level changes on the frost heave and mechanical properties of trapezoidal channels

Abstract In this research study, platforms with different heights were established for the purpose of simulating the different groundwater level conditions. Combined with the prototype channel, the influences of the groundwater level changes on the frost heave deformations in the foundation soil and on the frost heave force of the channel, as well as on the bending moment of the channel section and water content migration of the foundation soil, were studied by the method of mechanical analysis. The research results show that, after a comparative analysis of the ground temperatures in the same layer had been completed, the difference value was found to have been less than 5%. The frost heave of the foundation soil had decreased by 0.15 cm for every 1 cm reduction in the groundwater level. In addition, the maximum frost heave force of the channel was shown to have varied with the change of groundwater level. This study's theoretical calculations determined that the most unsafe groundwater level of a typical channel was 2.61 m. It was concluded that the increase of groundwater level can reduce the amount of soil moisture transfer, while the influence of groundwater level on frost heave of foundation soil can be effectively reduced by laying polystyrene boards.

Performance comparison of time‐of‐arrival estimation techniques for LTE signals in realistic multipath propagation channels

<h3>Abstract</h3> Long term evolution (LTE) signals have the potential for use in positioning, especially in challenging environments. The time-of-arrival (TOA)-based technique supported by LTE is attractive due to its high positioning accuracy. However, it is vulnerable to multipath propagation effects in typical LTE channels. This paper will summarize several existing advanced TOA estimators for LTE signals, i.e., first peak detection, information theoretic criteria, super-resolution algorithm, and delay-lock loop (DLL). Later, the paper will evaluate the TOA estimation performances of these techniques with multipath propagation effects and varying signal conditions using simulations. For the DLL, the multipath error envelope metric is assessed for different signal bandwidths. The root mean square errors of the TOA estimations are compared to evaluate suitable TOA estimators under various conditions. Finally, some other performance characteristics of these techniques are also discussed.

On BER analysis of nonlinear VLC systems under ambient light and imperfect/outdated CSI

Visible light communication (VLC) has emerged as a promising supplement to the existing radio frequency (RF) technology, which facilitates high speed communication for next generation communication systems. Although promising, the performance in a practical VLC system is severely impaired by ambient light interference. Furthermore, nonlinearity of light emitting diodes (LEDs) and imperfect/oudated channel state information (CSI) are other factors that degrade the achievable bit error rate (BER) performance. In this work, an analytical framework for analyzing the expression for BER of a wide class of modulation techniques is derived for an impaired VLC system considering: (a) ambient light interference, (b) LED nonlinearity, and (c) imperfect and outdated CSI. The derived analytical expressions for BER are validated through extensive computer simulations performed over typical VLC channels. Lastly, the utility of the derived analytical framework is demonstrated in the context of high data-rate VLC systems, wherein the performance of DC biased optical orthogonal frequency division multiplexing (DCO-OFDM) is quantified for VLC links impaired by the aforementioned degradations.

Lab on a rod: Size-based particle separation and sorting in a helical channel.

Size-based particle separation using inertial microfluidics in spiral channels has been well studied over the past decade. Though these devices can effectively separate particles, they require a relatively large device footprint with a typical outer channel radius of approximately 15 mm. In this paper, we describe a microfluidic device with a footprint diameter of 5.5 mm, containing a helical channel capable of inertial particle separation fabricated using abrasive jet micromachining. The separation of particles in several channel geometries was studied using wide-field fluorescence microscopy. A maximum separation efficiency of approximately 90% was achieved at a flow rate of 1.5 ml/min with a purity of approximately 95% at the outlet, where large particles were collected. An accompanying computational fluid dynamics model was developed to allow researchers to quickly assess the separation capability of their helical or spiral devices.

Flow instability in parallel-channel systems with ultra-supercritical water

In this study, a numerical code that applies a time-domain method is established to analyze the flow instability of a uniformly heated parallel-channel system. Nonlinear dynamics of the ultra-supercritical flow in the water wall are discussed. Results show that the inlet and outlet mass flow rates demonstrate antiphase. The mass flow rates with heat flux perturbations imposed on either single channel decline gradually with time, suggesting that flow stability can be maintained at normal operation. In addition, the effects of heat flux perturbation on transient responses of the typical parallel channels are studied. Results illustrate that the maximum of the inlet mass flow rate in both channels are high when perturbation is imposed on a strong heated channel. Moreover, flow in the stronger heated channel reveals more remarkable dynamic characteristics than in the weaker one. Approximately 141.6 and 139.8 s are needed for perturbation.1 and perturbation.2 to restore to steady state, respectively. Furthermore, data under different inlet temperatures and mass flow rates are calculated to generate the dimensionless instability boundary. When the inlet temperature is low, the inlet mass flow rate should be increased to stabilize the system. Otherwise, the effect of the mass flow rate on the instability boundary is almost negligible.

Architectures, standardisation, and procedures for 5G Satellite Communications: A survey

The 5G ecosystem is radically shifting Information and Communication Technologies (ICT) towards a system directly tailored and optimised to support vertical markets and services. In order to design and implement the ambitious 5G network, Satellite Communications (SatCom) have been recognised as a promising solution to extend and complement terrestrial networks in unserved or under-served areas, as reflected by recent commercial and standardisation endeavours. Within 3GPP, this is reflected in the novel Study Item on Non-Terrestrial Networks to introduce 5G (New Radio, as per 3GPP nomenclature) technologies in SatCom. However, typical satellite channel impairments, as large path losses, delays, and Doppler shifts, pose severe challenges to the realisation of a satellite-based 5G network. In this paper, we thoroughly review the standardisation process performed within 3GPP from Rel. 15 to the present, discussing the different technologies and the related system architectures and interfaces. Based on these discussions, we assess the impact of the satellite channel characteristics on the major physical and medium access control layers, i.e., Downlink Synchronisation, Random Access, and Hybrid Automatic Repeat reQuest. A set of potential solutions to the identified shortcomings is finally discussed.

A Beamforming Scheme With Doppler Suppression for High-Mobility Wireless Communications

In this letter, we consider the high-mobility wireless communications between a high speed train (HST) and a base station (BS) and propose a beamforming scheme with Doppler suppression for the stationary node BS. The typical Rician channel model is assumed, which occupies most of the HST communication scenarios. Based on the fact that the channel time-variation induces interference to the standard time-invariant signal model, the beamforming is then designed to maximize the signal-to-interference-plus-noise ratio (SINR) for both uplink and downlink transmissions. Simulation results are provided to verify that the channel time-variation can be effectively suppressed by the stationary BS through the proposed beamforming scheme.

An efficient technique for out-of-band power reduction for the eliminated CP-STC-shaped system for 5G requirements

The most dominant needs for the recent wireless mobile applications are higher bandwidth (BW) efficiency, higher energy efficiency higher quality of services (QOS). The main technique in 4G systems is OFDM but it suffers from some limitations such as large peak to average power ratio (PAPR), higher Out-of-Band (OOB) power radiation, and wasting bandwidth efficiency due to cyclic prefix (CP) extension. In his paper, these OFDM limitations will be reduced with low computational complexity compared to filter bank multicarriers (FBMC). The proposed scheme is based on symbol time compression (STC) for OFDM system. The proposed STC-Shaped system is achieved via interleaver-spreader and symbol shaper in the transmitter side in addition to equalization and combining processes in the receiver side. Comparative study between the proposed system and the conventional OFDM in case of additive white Gaussian noise (AWGN) and COST 207 typical multipath fading channel will be presented. The numerical results show that the proposed STC-Shaped scheme reduces OOB significantly. The proposed scheme improves BER in multipath Rayleigh fading although it is without CP. Thus, the proposed system is more robust against inter symbol interference (ISI) compared to conventional OFDM system. Also, the numerical results show that the PAPR of the proposed system is decreased significantly and also, it is derived theoretically. Also, the proposed scheme overcomes CP extension, and hence increases the bandwidth (BW) efficiency. Finally, the computational complexity for the proposed scheme is derived and it has very low complexity compared to FBMC. The system performance measurments has been fulfilled using cumulative distribution function (CDF), power spectral density (PSD) and bit error rate (BER).

Math model of a power beam feeding a spacecraft under conditions of intermittent power supply

The paper discusses transmission, reception, conversion and consumption of energy of laser and microwave radiation from Earth or space power plants. It proposes a classification of advanced systems for remote supply of power to spacecraft (SC). It addresses practicability of using remote power supply to SC under various operational conditions. The paper formulates the problem of evaluating the capability of the existing SC power supply systems to receive and convert emissions from additional sources. An analysis of criteria for the quality of pulsed or rapidly varying flow of energy into a SC power supply system. It reviews the structures of typical channels of power consumption in a SC power supply system. An equivalent circuit replacing receivers of pulsed or rapidly changing radiation is described. A math model is proposed for a power consumption channel operating under conditions of intermittent power supply to photovoltaic converters. Math modeling results are presented and analyzed. Key words: space power plant, solar array, onboard power supply system, power consumption channel, voltage converters.

Research on the Comprehensive Optimization of the Hydraulic Performance and Frost-Heaving Resistance of a Parabolic Channel

Hydraulic performance and frost-heaving resistance should be considered simultaneously in the channel design of seasonally frozen soil areas. Quadratic parabolic channels have good water and sand transport capacities and high frost-heaving resistances. The width–depth ratio of a parabola determines its section structural form, which in turn determines the hydraulic performance and frost-heaving resistance. In this research, based on the current lack of a comprehensive optimization method that accounts for the hydraulic performance and frost-heaving resistance of the cross-section structures of parabolic channels, a multi-objective optimization model was established with the goal of achieving a minimum cross-sectional flow area and a uniform channel section force. Taking the flow velocity, the width–depth ratio and the crack resistance of concrete lining plate as constraints, the α method of the linear weighted sum method was used to optimize the calculation, and the comprehensive optimal quadratic parabolic channel section was obtained. The comprehensive optimal section of an actual parabolic channel in the Shijin Irrigation District was determined using this method, and the comprehensive optimal section was analyzed and compared to the original design section and two typical parabolic channel sections. The comprehensive optimal section was compared with the original design section in the Shijin Irrigation District. The force uniformity of the optimal section was 23.2% better, the hydraulic performance was 1.96% better, and the land use was 12.35% less. Compared with the values for the hydraulic optimal section, the maximum positive and negative bending moments of the comprehensive optimal section decreased by 5.6% and 11.89%, respectively, and the force uniformity increased by 7.62%. Additionally, compared with the values for the practical economic section, the force uniformity and the hydraulic performance of the comprehensive optimal section increased by 1.79% and 0.2%, respectively, and the land use decreased by 4.49%. Thus, the comprehensive optimal section met the engineering requirements and it could provide a reference for the design and selection of parabolic channels in seasonally frozen soil areas.

Inertial gravity currents over a permeable bottom in trapezoidal type cross-section channels: shallow-water and box-model solutions

We consider an inertial gravity current spreading over a horizontal permeable floor in channels of trapezoidal type cross-section (CS). A closed one-layer shallow-water Boussinesq inviscid formulation is presented. It is shown that initially the porosity has little influence on the spreading of the current, but it decreases the distance of propagation during the following stages of propagation. The position of the porosive boundary is also examined. Qualitatively, the behaviour of the current is similar to one spreading over a fully-permeable bottom, however the current is faster as the porosive domain starts far from the origin. We illustrate the methodology for flows in typical trapezoidal type CS channels $$f(z) = 1/2(1+z^{\alpha })$$ (here the constant $$\alpha$$ is positive) and show that the slowest propagation is achived in containers of rectangular form ( $$\alpha =0$$ ).

Bidirectional Controlled Quantum Teleportation Using Eight-Qubit Quantum Channel in Noisy Environments

In this work, a novel protocol is proposed for bidirectional controlled quantum teleportation (BCQT) in which a quantum channel is used with the eight-qubit entangled state. Using the protocol, two users can teleport an arbitrary entangled state and a pure two-qubit state (QBS) to each other simultaneously under the permission of a third party in the role of controller. This protocol is based on the controlled-not operation, appropriate single-qubit (SIQ) UOs, and SIQ measurements in the Z and X-basis. Also, in this paper, a new criterion of merit named as (predictability of the controller’s qubit (QB) by the eavesdropper) is introduced, and the protocol is improved based on it. Then, the proposed protocol is investigated in two typical noisy channels, the amplitude-damping noise (ADN) and the phase-damping noise (PDN). The analysis of the protocol in the noisy environment shows that it only depends on the amplitude of the initial state and the decoherence noisy rate (DR).

Review on effect of two-phase interface morphology evolution on flow and heat transfer characteristics in confined channel

In this paper, the effect of two-phase interface morphology evolution on the flow and heat transfer characteristics in confined channels are reviewed in detail, which is one of the typical channel structures for the nuclear reactor core. The investigated contents mainly come from the open literature. In addition, this paper focuses on the important phenomena and methods proposed in recent decades, which simultaneously includes the closely related studies of authors published in the last several years. The primary contents of this paper mainly includes the following aspects: (1) the definition of confined channel is introduced based on the summary of various distinguishing criterions; (2) the effect of two-phase interface morphology on the flow and resistance characteristics is concluded, which are mainly related to the adiabatic flow conditions, thus the complex influence of boiling phenomenon can be neglected; (3) the effect of two-phase interface morphology on the flow boiling heat transfer characteristics is researched. Moreover, the development of flow boiling heat transfer model is reviewed, and the corresponding proposed model is introduced, which innovatively reflects the feature of confined channel and is considered worthy of further development; (4) the effect of two-phase interface morphology on the flow instability and boiling crisis characteristics are reviewed. Especially, the coupling relationship between them are introduced with the bubble dynamic behaviors dependent on the published research achievement of authors; (5) the material surface modification technology is proposed to be the enhanced heat transfer technology, which is also supposed to be the future research point for reactor thermal-hydraulics.