Two-phase flow instability in a parallel multichannel system

The two-phase flow instabilities observed in through parallel multichannel can be classified into three types,of which only one is intrinsic to parallel multichannel systems.The intrinsic instabilities observed in parallel multichannel system have been studied experimentally.The stable boundary of the flow in such a parallel-channel system are sought,and the nature of inlet flow oscillation in the unstable region has been examined experimentally under various conditions of inlet velocity,heat flux,liquid temperature,cross section of channel and entrance throttling.The results show that parallel multichannel system possess a characteristic oscillation that is quite independent of the magnitude and duration of the initial disturbance,and the stable boundary is influenced by the characteristic frequency of the system as well as by the exit quality when this is low,and upon raising the exit quality and reducing the characteristic frequency,the system increases its instability,and entrance throttling effectively contributes to stabilization of the system.

Accurate Source-Receiver Positioning Method for a High-Resolution Deep-Towed Multichannel Seismic Exploration System

The near-seabed multichannel seismic exploration systems have yielded remarkable successes in marine geological disaster assessment,marine gas hydrate investigation,and deep-sea mineral exploration owing to their high vertical and horizontal resolution.However,the quality of deep-towed seismic imaging hinges on accurate source-receiver positioning information.In light of existing technical problems,we propose a novel array geometry inversion method tailored for high-resolution deep-towed multichannel seismic exploration systems.This method is independent of the attitude and depth sensors along a deep-towed seismic streamer,accounting for variations in seawater velocity and seabed slope angle.Our approach decomposes the towed line array into multiline segments and characterizes its geometric shape using the line segment distance and pitch angle.Introducing optimization parameters for seawater velocity and seabed slope angle,we establish an objective function based on the model,yielding results that align with objective reality.Employing the particle swarm optimization algorithm enables synchronous acquisition of optimized inversion results for array geometry and seawater velocity.Experimental validation using theoretical models and practical data verifies that our approach effectively enhances source and receiver positioning inversion accuracy.The algorithm exhibits robust stability and reliability,addressing uncertainties in seismic traveltime picking and complex seabed topography conditions.

Non-Central Zone 3D Sound Field Reproduction for Multichannel System

The 22.2 multichannel system and its simplified system with 10-channel and 8-channel have been proposed, which brings people 3 D listening experience. But these systems could only accurately reproduce sound field at a central listening point which is called sweetspot. In order to solve this problem, this paper proposes a non-central zone sound field reproduction method PVMDZ（particle velocity matching between different zones） based on the physical property of sound. The proposed method matches the physical property of sound of non-central zone in reconstructed sound field with that of central zone in original sound field, so the reproduced non-central zone would produce the same listening experience as the central zone of the original system does. By experiments, we compare the performances of the proposed method with the traditional one, and the result proves that the sound field error of proposed method is reduced.

FPGA SoC Based Multichannel Data Acquisition System with Network Control Module

Normally, Data acquisition (DAQ) is used to acquire the signals from different devices like sensors, transducers, actuators etc. The data acquisition is also used to analyze the signals, digitizing the signals and acquiring the signals from different inputs. The main drawbacks in data acquisition system are data storage, hardware size and remote monitoring. The System-on-Chip Field Programmable Gate Array (SoC-FPGA) is used in the proposed system in the aim to reduce the hardware and memory size. Further to provide remote monitoring with Ethernet/Wi-Fi, the Network Control Module (NCM) is integrated with Data acquisition and processing module for the communication between the systems. This developed system achieves high resolution with memory reduction, reduced hardware size, fast remote monitoring and control. It is used for real time processing in DAQ and signal processing. For fault tolerance and portability, the full system reconfigurability based FPGA acts as the best solution and the system can be reused with different configurations. The control of data acquisition and the subsequent management of data are coded in LabVIEW. LabVIEW tool is used to design and develop a four-channel Data Acquisition and Processing (DAQP) unit. National Instruments Data Acquisition (NIDAQ) and National Instruments Field Programmable Gate Array (NIFPGA) are used to test and implement the design for real time processing. This is designed to provide high accuracy, storage and portability.

On One Model of Multichannel Queuing System with Unreliable Repairable Servers and Input Memory

The work deals with the development of analytical model of multichannel technical queuing system with unreliable servers and input memory where server failure flows and incoming request flows comply with Poissonian laws, while the flows of failed facilities repairs and flows of incoming requests comply with exponential laws of probability distribution. Random process of system change-over is a Markovian process with continuous time and discrete states. Relations binding basic parameters and output characteristics of the system indicated are obtained as probabilities of system staying in the given moment in one of the possible states. The proposed model is the most generalized compared to some models known in literature which could be considered as special cases of the considered model.

Insight into the dynamic adsorption behavior of graphene oxide multichannel architecture toward contaminants

Graphene oxide(GO) channels exhibit unique mass transport behaviors due to their flexibility, controllable thinness and extraordinary physicochemical properties, enabling them to be widely used for adsorption and membrane separation. Nevertheless, the adsorption behavior of nanosized contaminants within the channels of GO membrane has not been fully discussed. In this study, we fabricated a GO membrane(PGn, where n represents the deposition cycles of GO) with multi channels via the crosslinking of GO and multibranched poly(ethyleneimine)(PEI). Phenol was used as molecular probe to determine the correlations between dynamic adsorption behavior and structural parameters of the multilevel GO/PEI membrane. PG8 shows higher adsorption capacities and affinity, which is predominantly attributed to the multichannel structure providing a large specific surface for phenol adsorption, enhancing the accessibility of active sites for phenol molecules and the transport of phenol. Density functional theory calculations demonstrate that the adsorption mechanism of phenol within GO channel is energetically oriented by hydrogen bonds, which is dominated by oxygen-containing groups compared to amino groups. Particularly, the interfaces which facilitate strong π-π interaction and hydrogen bonds maybe the most active regions. Moreover, the as-prepared PG8 membrane showed outstanding performance for other contaminants such as methyl orange and Cr(VI). It is anticipated that this study will have implications for design of GO-related environmental materials with enhanced efficiency.

Design of a High Precision Multichannel 3D Bioprinter

Three-dimensional(3D)printing technology is expected to solve the organ shortage problem.However,owing to the accuracy limitations,it is difficult for the current bioprinting technology to achieve an accurate control of the spatial position and distribution of a single cell or single component droplet.In this study,to accurately achieve the directional deposition of different cells and biological materials in the spatial position for the construction of large transplantable tissues and organs,a high-precision multichannel 3D bioprinter with submicron-level motion accuracy is designed,and concurrent and synergistic printing methods are proposed.Based on the high-precision motion characteristics of the gantry structure and the requirements of concurrent and synergistic printing,a 3D bioprint-ing system with a set of 6 channels is designed to achieve six-in-one printing.Based on the Visual C++environ-ment,a control system software that integrates the programmable multi-axis controller(PMAC)motion,pneumatic,and temperature control subsystems was developed and designed.Finally,based on measurements and experiments,the 3D bioprinter and its control system was verified to fulfil the requirements of multichannel,concurrent,and syn-ergistic printing with submicron-level motion accuracy,significantly shortening the printing time and improving the printing efficiency.This study not only provides an equipment basis for printing complex heterogeneous tissue structures,but also improves the flexibility and functionality of bioprinting,and ultimately makes the construction of complex multicellular tissues or organs possible.

A multichannel human-swarm robot interaction system in augmented reality

Background A large number of robots have put forward the new requirements for human robot interaction.One of the problems in human-swarm robot interaction is how to naturally achieve an efficient and accurate interaction between humans and swarm robot systems.To address this,this paper proposes a new type of human-swarm natural interaction system.Methods Through the cooperation between three-dimensional(3D)gesture interaction channel and natural language instruction channel,a natural and efficient interaction between a human and swarm robots is achieved.Results First,A 3D lasso technology realizes a batch-picking interaction of swarm robots through oriented bounding boxes.Second,control instruction labels for swarm-oriented robots are defined.The instruction label is integrated with the 3D gesture and natural language through instruction label filling.Finally,the understanding of natural language instructions is realized through a text classifier based on the maximum entropy model.A head-mounted augmented reality display device is used as a visual feedback channel.Conclusions The experiments on selecting robots verify the feasibility and availability of the system.

Morphological features and endovascular repair for type B multichanneled aortic dissection: A case report

BACKGROUND Among the various types of aortic dissection,multichanneled aortic dissection(MCAD)differs from classic double-channeled aortic dissection and involves the formation of an additional false lumen in the aortic wall or the flaps.It is considered a relatively rare condition with high perioperative mortality and morbidity.However,the morphological characteristic and the optimal therapeutic strategy for MCAD has not been fully determined.CASE SUMMARY A 64-year-old man presented to our hospital with severe epigastric abdominal pain radiating to the back that was associated with nausea without emesis.A computed tomography angiogram was performed that revealed a type B aortic dissection with multiple channels extending from the level of the left subclavian artery to the bilateral femoral arteries.We used a medical three-dimensional modeling(3D)modeling system to identify the location and extension of multiple lumens from different angles.It also precisely located the two primary entries leading to the false lumens,which helped us to exclude the two false lumens with one stent-graft.CONCLUSION By applying medical 3D modeling system,we discover the fragility of aortic wall and the collapse of true lumen caused by the multiple false lumens are the two morphological features of MCAD.

卡斯卡迪亚慢滑移信息的GNSS时空探测

针对断层慢滑移时空分布信息探测困难的问题,基于全球卫星导航系统(GNSS)坐标序列,提出一种利用多通道奇异谱分析(MSSA)探测卡斯卡迪亚消减带慢滑移事件时空分布的方法:根据慢滑移分量的振荡特点确定窗口长度,采用时间迟滞矩阵对协方差阵进行增广,以提高对异常信息的识别能力;对振幅归一化获取空间响应,通过快速傅里叶变换分析慢滑移频谱特征。结果表明,卡斯卡迪亚消减带2007-01-05—2007-02-23和2008-04-22—2008-06-14发生了2次慢滑移事件,2次事件呈东南、西北区域的反向运动特征,且东南部响应程度明显高于西北地区;频谱特征显示,慢滑移信息表现为低频特征,且主要为随机游走噪声。研究结果可为板内地震前兆性信息探测提供参考。

门控卷积神经网络多通路声学回声消除算法

多通路声重放系统能够增强听者的现实感与空间感,但在免提通信条件下,其不可避免会受到噪声和回声干扰,严重影响通信质量。针对上述问题,提出了一种基于门控卷积循环神经网络的多通路声学回声消除和噪声抑制方法。该方法以传声器接收信号和重放声道的压缩复数谱为网络输入,以近端语声的压缩复数谱为网络的输出目标,直接从传声器拾取信号中恢复近端纯净语声,无需对声重放信号进行去相关处理,解决了传统自适应滤波方法中存在的非唯一解问题,同时保证了多通路声重放质量。仿真和真实声学环境实验均表明该文所提出的方法可显著消除多通路声重放系统的噪声和回声,在语声质量和回声返回衰减增益方面均优于传统算法。

2010-2014年哀牢山亚热带常绿阔叶林土壤呼吸数据集

亚热带森林是我国分布面积最大的森林类型,在调控全球气候变化和维持大气碳平衡中具有重要作用。土壤通过呼吸作用排放的碳是大气CO_(2)的主要来源,土壤碳库的细微变化也会显著影响大气CO_(2)的浓度,因此目前亚热带森林土壤碳储量的大小及动态变化特征受到广泛关注。云南哀牢山是我国重要的亚热带森林分布区。本研究依托云南哀牢山森林生态系统国家野外科学观测研究站,利用全自动多通道观测系统开展了亚热带常绿阔叶林土壤呼吸的连续测定,经过严格的数据质量控制和评估,将2010-2014年的土壤呼吸的监测数据收集与整理,包括土壤5 cm温度(Ts)、土壤10 cm含水量(SWC)和土壤呼吸(Rs),并形成日、月和年尺度三类数据集。本数据集对于揭示气候变化对亚热带常绿阔叶林土壤生态过程的影响、正确评估土壤有机碳排放和森林生态系统管理具有重要意义,也为进一步研究气候变暖等全球变化对土壤呼吸组分尤其是土壤有机碳排放的影响提供经验和理论基础。

一种用于多通道移液装置性能验证的光度法系统

针对多通道移液装置的校准和验证,本文介绍了一种全新的多通道验证系统(MVS),并基于双染料比率光度法,对每个单独通道的准确性和精密度进行测量。实验证明:该系统应用范围较广,校准范围可覆盖(2~200)μL,且结果可溯源至国家标准。同时,基于MVS自身的稳定性和操作的便利性,在实验室环境中可用于对自动移液设备进行验证,确保仪器设备的性能状态。

Stepwise Fabrication of Co-Embedded Porous Multichannel Carbon Nanofibers for High-Efficiency Oxygen Reduction

A novel nonprecious metal material consisting of Coembedded porous interconnected multichannel carbon nanofibers(Co/IMCCNFs) was rationally designed for oxygen reduction reaction(ORR)electrocatalysis.In the synthesis,ZnCo2O4 was employed to form interconnected mesoporous channels and provide highly active Co3O4/Co core–shell nanoparticle-based sites for the ORR.The IMC structure with a large synergistic effect of the N and Co active sites provided fast ORR electrocatalysis kinetics.The Co/IMCCNFs exhibited a high half-wave potential of 0.82 V(vs.reversible hydrogen electrode) and excellent stability with a current retention up to 88% after 12,000 cycles in a current–time test,which is only 55% for 30 wt% Pt/C.

Local inflammatory response to gastroesophageal reflux:Association of gene expression of inflammatory cytokines with esophageal multichannel intraluminal impedance-pH data

BACKGROUND Gene expression of inflammatory cytokines may take part in the pathophysiology of different forms of gastroesophageal reflux disease(GERD).AIM To explore gene expression of inflammatory cytokines in esophageal mucosa in patients with erosive esophagitis(EE)and non-erosive forms of GERD(NERD)and its association with data of esophageal multichannel intraluminal impedancepH(MII-pH)measurements.METHODS This was a single-center prospective study.Esophageal mucosa samples were taken from the lower part of the esophagus during endoscopy.Expression of interleukin(IL)-1β,IL-10,IL-18,tumor necrosis factorα(TNFA),toll-like receptor 4(TLR4),GATA binding protein 3(GATA3),differentiation cluster 68(CD68)andβ-2 microglobulin genes in esophageal mucosa was assessed with ImmunoQuantex assays.MII-pH measurements were performed on all the participants.Diagnosis of GERD was confirmed by the results of the MII-pH data.Based on the endoscopy,patients were allocated to the groups of EE and NERD.The control group consisted of non-symptomatic subjects with normal endoscopy and MII-pH results.We used nonparametric statistics to compare the differences between the groups.Association of expression of the mentioned genes with the results of the MII-pH data was assessed with Spearman’s rank method.RESULTS Data from 60 patients with GERD and 10 subjects of the control group were available for the analysis.Higher expression of IL-18(5.89±0.4 vs 5.28±1.1,P=0.04)and GATA3(2.92±0.86 vs 2.23±0.96,P=0.03)was found in the EE group compared to NERD.Expression of IL-1β,IL-18,TNFA,and TLR4 was lower(P<0.05)in the control group compared to EE and NERD.Esophageal acid exposure correlated with the expression of IL-1β(Spearman’s rank r=0.29),IL-18(r=0.31),TNFA(r=0.35),GATA3(r=0.34),TLR4(r=0.29),and CD68(r=0.37).Mean esophagealрНcorrelated inversely with the expression of IL-18,TNFA,GATA3,TLR4,and CD68.No association of gene expression with the number of gastroesophageal refluxes was found.CONCLUSION In patients with EE,local expression of IL-18 and GATA3 was higher compared to subjects with NERD.Esophageal acid exposure correlated directly with expression of IL-1β,IL-18,TNFA,TLR4,CD68,andβ-2 microglobulin genes.Inverse correlation was revealed between expression of IL-18,TNFA,GATA3,TLR4,and CD68 and mean esophageal pH.

Experimental study on energy characteristics and ignition performance of recessed multichannel plasma igniter

In the extreme conditions of high altitude,low temperature,low pressure,and high speed,the aircraft engine is prone to flameout and difficult to start secondary ignition,which makes reliable ignition of combustion chamber at high altitude become a worldwide problem.To solve this problem,a kind of multichannel plasma igniter with round cavity is proposed in this paper,the three-channel and five-channel igniters are compared with the traditional ones.The discharge energy of the three igniters was compared based on the electric energy test and the thermal energy test,and ignition experiments was conducted in the simulated high-altitude environment of the component combustion chamber.The results show that the recessed multichannel plasma igniter has higher discharge energy than the conventional spark igniter,which can increase the conversion efficiency of electric energy from 26%to 43%,and the conversion efficiency of thermal energy from 25%to 73%.The recessed multichannel plasma igniter can achieve greater spark penetration depth and excitation area,which both increase with the increase of height.At the same height,the inlet flow helps to increase the penetration depth of the spark.The recessed multichannel plasma igniter can widen the lean ignition boundary,and the maximum enrichment percentage of lean ignition boundary can reach 31%.

Analysis of Multichannel ALOHA and CSMA Protocols－Normal and Slotted Versions

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Noise Reduction Technique Applied to the Multichannel Analysis of Surface Waves

This paper shows the presence of noises and technique to reduce these noises during the surface wave analysis. The frequency-dependent properties of Rayleigh-type surface waves can be used for imaging and characterizing the shallow subsurface. Interference by coherent source-generated noise inhibits the reliability of shear-wave velocities determined through inversion of the phase velocities of Rayleigh waves. Among these interferences by non-planar, non-fundamental mode Rayleigh waves （noise） are body waves, scattered and non-source-generated surface waves, and highermode surface waves. For the reduction of noise, the filtering technique is implemented in this paper for the multichannel analysis of surface wave method （MASW）. With the de-noising technique during the MASW method, more robust and reliable outcome is achieved. The significance of this paper is to obtain pre-awareness about noises during surface wave analysis and take better outcomes with denoising performance in near surface soil investigations.

A QoS-Based Multichannel MAC Protocol for Two-Tiered Wireless Multimedia Sensor Networks

Rapid penetration of small customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. Offering precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However offering some better QoS for wireless multimedia over sensor networks raises significant challenges. In this paper, we propose an adaptive Cross-Layer multi-channel QoS-MAC protocol to support energy-efficient, high throughput, and reliable data transmission in Wireless Multimedia Sensor Network (WMSNs). Our proposed protocol use benefit of TDMA and CSMA/CA to adaptively assign channels and timeslots to active multimedia sensor nodes in clusters. Simulations show that the proposed system achieves the performance objectives of WMSNs with increased network throughput at the cost of a small control and energy overhead.

Multichannel imaging for monitoring chemical composition and germination capacity of cowpea(Vigna unguiculata) seeds during development and maturation

This study aimed to set a computer-integrated multichannel spectral imaging system as a high-throughput phenotyping tool for the analysis of individual cowpea seeds harvested at different developmental stages. The changes in germination capacity and variations in moisture, protein and different sugars during twelve stages of seed development from 10 to 32 days after anthesis were nondestructively monitored. Multispectral data at 20 discrete wavelengths in the ultraviolet, visible and near infrared regions were extracted from individual seeds and then modelled using partial least squares regression and linear discriminant analysis(LDA) models. The developed multivariate models were accurate enough for monitoring all possible changes occurred in moisture, protein and sugar contents with coefficients of determination in prediction R^(2) of 0.93, 0.80 and 0.78 and root mean square errors in prediction(RMSEP) of 6.045%, 2.236% and 0.890%, respectively. The accuracy of PLS models in predicting individual sugars such as verbascose and stachyose was reasonable with R~2 of 0.87 and 0.87 and RMSEP of 0.071%and 0.485%, respectively;but for the prediction of sucrose and raffinose the accuracy was relatively limited with R^(2) of 0.24 and 0.66 and RMSEP of 0.567% and 0.045%, respectively. The developed LDA model was robust in classifying the seeds based on their germination capacity with overall correct classification of96.33% and 95.67% in the training and validation datasets, respectively. With these levels of accuracy,the proposed multichannel spectral imaging system designed for single seeds could be an effective choice as a rapid screening and non-destructive technique for identifying the ideal harvesting time of cowpea seeds based on their chemical composition and germination capacity. Moreover, the development of chemical images of the major constituents along with classification images confirmed the usefulness of the proposed technique as a non-destructive tool for estimating the concentrations and spatial distributions of moisture, protein and sugars during different developmental stages of cowpea seeds.