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...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.展开更多
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 par...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.展开更多
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 acq...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.展开更多
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 interact...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.展开更多
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...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.展开更多
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 la...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.展开更多
As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limit...As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limitation,this paper proposes a multichannel spectral fitting(MSF)method.The MSF method aims to enhance seismic resolution by considering the spectral characteristics and the correlations between adjacent seismic traces.The key to the MSF method involves utilizing the amplitude spectrum of the attenuated Ricker wavelet to construct an objective function for spectral fitting,leading to improved seismic resolution.Furthermore,the MSF method establishes the correlation between adjacent seismic traces as a constraint to stably solve the target parameters based on the entire seismic spectrum,which helps obtain horizontally consistent and more realistic seismic signals.Synthetic and field seismic examples demonstrate that the proposed method not only provides higher-resolution seismic signals but also reveals more fine details of thin reservoirs compared to the time-variant spectral whitening method.It is concluded that the MSF method is a promising tool for seismic signal processing.展开更多
Enhancing the ignition system performance of turbo engines is crucial,with a focus on rapidly and reliably igniting the entire combustor in low-temperature,low-pressure,high-speed inlet flow conditions.This challenge ...Enhancing the ignition system performance of turbo engines is crucial,with a focus on rapidly and reliably igniting the entire combustor in low-temperature,low-pressure,high-speed inlet flow conditions.This challenge has garnered international attention.To address the issue of reliable ignition in the combustors of advanced propulsion system,this paper proposes a Multichannel Jet Enhanced Plasma Igniter(MJEPI) and conducts comparative experimental studies with the conventional spark igniter in a component-level dual-dome swirl combustor.The ignition limit in the combustor is obtained and the ignition processes are recorded.Experimental results demonstrate that the MJEPI significantly improves the ignition performance at high altitude.Specifically,at 0 km and 6 km for ground start-up,ignition limit is extended by 36% and 29%,respectively.At 6 km and 12 km for high-altitude relight,ignition limit is extended by 32% and 21%,respectively.The maximum ignition height is increased by 2.3 km,as determined by the global equivalence ratio of 1.The primary reason for these improvements is attributed to the larger initial flame kernel with greater penetration depth generated by MJEPI,which enables it to withstand more sever conditions such as low temperature,low pressure,and poor kerosene spray quality at elevated altitudes.展开更多
Traditional deconvolution methods based on single-channel inversion do not consider the spatial structural relation between channels,and hence,they yield high-resolution results with the existing transverse inconsiste...Traditional deconvolution methods based on single-channel inversion do not consider the spatial structural relation between channels,and hence,they yield high-resolution results with the existing transverse inconsistency or discontinuity.Therefore,in this study,the local dip angle was used to obtain the structural information and construct the spatial structurally constraint operator.This operator is then introduced into multichannel deconvolution as a regularization operator to improve the resolution and maintain the transverse continuity of seismic data.Model tests and actual seismic data processing have demonstrated the effectiveness and practicability of this method.展开更多
A multichannel matching pursuit（MMP）algorithm is proposed to decompose the one-dimensional multichannel non-stationary magnetoencephalography（MEG）signal at a single-trial level.The single-channel matching pursuit...A multichannel matching pursuit（MMP）algorithm is proposed to decompose the one-dimensional multichannel non-stationary magnetoencephalography（MEG）signal at a single-trial level.The single-channel matching pursuit（MP）linearly decomposes the signal into a set of Gabor atoms,which are adaptively chosen from an overcomplete dictionary with good time-frequency characters.The MMP is the extension of the MP,which represents multichannel signals using linear combination of Gabor atoms with the same occurrence,frequency,phase,and time width,but varying amplitude in all channels.The results demonstrate that the MMP can optimally reconstruct the original signal and automatically remove artifact noises.Moreover,the coherence between the 3D source reconstruction and the prior knowledge of psychology further suggests that the MMP is effective in MEG single-trial processing.展开更多
The fabrication of multicomponent heterojunctions is an effective strategy to improve the performance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic perf...The fabrication of multicomponent heterojunctions is an effective strategy to improve the performance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic performance of ZnO /TiO2 composites by the formation of multichannel charge separated heterojunctions. ZnO /P25 composites were prepared by an incipient wetness impregnation method, and applied for the photocatalytic destruction of gaseous toluene. The ZnO /P25 composites consist of anatase TiO2（ATiO2）, rutile TiO2（RTiO2） and hexagonal zincite structures. The parasitic phase of ZnO in P25 leads to the formation of ZnO（002）/ATiO2（101）/RTiO2（110） heterojunctions that exhibit enhanced light absorption and improved multichannel electron/hole separation. ZnO /P25 heterojunctions can completely oxidize toluene into CO2 and H2O under ultraviolet light irradiation at room temperature, and show enhanced photocatalytic activity in comparison with P25 owing to the efficient electron-hole separation. Such a multichannel charge separated design strategy may provide new insight into the design of highly effective photocatalysts and their potential technological applications.展开更多
When used with large energy sparkers, marine multichannel small-scale high-resolution seismic detection technology has a high resolution, high-detection precision, a wide applicable range, and is very flexible. Positi...When used with large energy sparkers, marine multichannel small-scale high-resolution seismic detection technology has a high resolution, high-detection precision, a wide applicable range, and is very flexible. Positive results have been achieved in submarine geological research, particularly in the investigation of marine gas hydrates. However, the amount of traveltime difference information is reduced for the velocity analysis under conditions of a shorter spread length, thus leading to poorer focusing of the velocity spectrum energy group and a lower accuracy of the velocity analysis. It is thus currently debatable whether the velocity analysis accuracy of short-arrangement multichannel seismic detection technology is able to meet the requirements of practical application in natural gas hydrate exploration. Therefore, in this study the bottom boundary of gas hydrates(Bottom Simulating Reflector, BSR) is used to conduct numerical simulation to discuss the accuracy of the velocity analysis related to such technology. Results show that a higher dominant frequency and smaller sampling interval are not only able to improve the seismic resolution, but they also compensate for the defects of the short-arrangement, thereby improving the accuracy of the velocity analysis. In conclusion, the accuracy of the velocity analysis in this small-scale, high-resolution, multi-channel seismic detection technology meets the requirements of natural gas hydrate exploration.展开更多
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 esophag...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.展开更多
Objective： To analyze reflux parameters by means of combined multichannel intraluminal impedance and pH （MII-pH） monitoring in patients with gastroesophageal reflux disease （GERD） symptoms off medication, and to ...Objective： To analyze reflux parameters by means of combined multichannel intraluminal impedance and pH （MII-pH） monitoring in patients with gastroesophageal reflux disease （GERD） symptoms off medication, and to find the reflux characteristics of Chinese GERD patients and the influences of gender, age, body posture, and body mass index （BMI） on gastroesophageal reflux （GER）. Methods： Between Dec. 2008 and May 2014, 125 patients with typical GERD symptoms were subjected to 24-h MII-pH monitoring. Twelve patients with normal MII-pH profiles were not considered for analysis. The reflux parameters of 113 GERD patients with abnormal Mll-pH results were analyzed. Results： （1） DeMeester scores were above the normal range in 46.90% （53/113） of GERD patients. Weakly acidic refluxes were prevalent in GERD patients, and the frequency of abnormal weakly acidic reflux was 75.22% （85/113）. The frequencies of abnormal symptom index （SI） and symptom association probability （SAP） were 19.47% （22/113） and 14.16% （16/113）, respectively. （2） The frequencies of DeMeester scores, the %time at pH〈4, and the numbers of reflux episodes and of long reflux episodes 〉5 min were significantly higher in male patients than in female patients. （3） The %time at pH〈4 was much higher during upright periods than during supine periods. During supine periods, 31.86% （36/113） of GERD patients had delayed bolus clearance time, compared with 19.47% （22/113） during upright periods. （4） The number of abnormal DeMeester scores, %time at pH〈4, and the number of acid refluxes during upright periods were significantly higher in obese GERD patients than in GERD patients with a normal BMI. Over- weight GERD patients also had many more acid refluxes during upright periods than GERD patients with a normal BMI Conclusions： Weakly acidic refluxes were prevalent in Chinese GERD patients. The factors male, gender, upright position, obesity （BMI〉25）, but not age, may increase the frequency and severity of GER.展开更多
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,...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.展开更多
AIM To evaluate the agreement of multichannel intraluminal impedance-p H monitoring(MII-p HM) and gastroesophageal reflux scintigraphy(GES) for the diagnosis of gastroesophageal reflux disease. METHODS Seventy-five co...AIM To evaluate the agreement of multichannel intraluminal impedance-p H monitoring(MII-p HM) and gastroesophageal reflux scintigraphy(GES) for the diagnosis of gastroesophageal reflux disease. METHODS Seventy-five consecutive patients with suspectedgastroesophageal reflux disease(GERD) underwent 24-h combined MII-p HM recording and one hour radionuclide scintigraphy during the course of the MIIpH M study. Catheters with 6 impedance channels and 1 p H sensor were placed transnasally. Impedance and p H data analysis were performed automatically and manually. For impedance monitoring, reflux was defined as a retrograde 50% drop in impedance, starting distally and propagating retrogradely to at least the next two more proximal measuring channels. Reflux index(RI, percentage of the entire record that esophageal p H is < 4.0) greater than 4.2% for p HM and number of refluxes more than 50 for 24 h for MII were accepted as positive test results. At scintigraphy, 240 frames of 15 seconds duration were acquired in the supine position. Gastroesophageal reflux was defined as at least one reflux episode in the esophagus. After scintigraphic evaluation, impedance-pH recordings and scintigraphic images were evaluated together and agreement between tests were evaluated with Cohen's kappa.RESULTS Sufficient data was obtained from 60(80%) patients(34 male, 56.7%) with a mean age of 8.7 ± 3.7 years(range: 2.5-17.3 years; median: 8.5 years). Chronic cough, nausea, regurgitation and vomiting were the most frequent symptoms. The mean time for recording of MII-pH M was 22.8 ± 2.4 h(range: 16-30 h; median: 22.7 h). At least one test was positive in 57(95%) patients. According to diagnostic criteria, GERD was diagnosed in 34(57.7%), 44(73.3%), 47(78.3%) and 51(85%) patients by means of p HM, MII, GES and MII-p HM, respectively. The observed percentage agreements/κ values for GES and p HM, GES and MII, GES and MII-p HM, and MII and p HM are 48.3%/-0.118; 61.7%/-0.042; 73.3%/0.116 and 60%/0.147, respectively. There was no or slight agreement between GES and p HM alone, MII alone or MII-p HM. p H monitoring alone missed 17 patients compared to combined MII-p HM. The addition of MII to pH monitoring increased the diagnosis rate by 50%.CONCLUSION No or slight agreement was found among p H monitoring, MII monitoring, MII-pH monitoring and GES for the diagnosis of gastroesophageal reflux disease.展开更多
Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low cost.Nevertheless,the difficulty in finding appropriate electr...Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low cost.Nevertheless,the difficulty in finding appropriate electrode materials that can efficiently store the larger K ions has hindered their practical application.Herein,we report a novel anode material,N-doped multichannel carbon nanofibers embedded with porous CoS nanoprisms(CSP@NMCNF),for high-performance PIBs.The CSP@NMCNF was synthesized using a two-step strategy comprising of the electrospinning of Co acetate hydroxide nanoprism/binary polymer blend and a subsequent heat treatment.The porous CoS nanoprisms with an anisotropic morphology were well aligned along the length axis of the N-doped multichannel carbon nanofibers,thus ensuring their structural stability during the repeated charge-discharge process.In addition,numerous pores facilitated the transport of electrons and ions.Accordingly,the CSP@NMCNF anode exhibited excellent electrochemical performance,delivering a high specific capacity of 368 mAh·g^(-1)at 0.5 A·g^(-1)after 200 cycles and excellent rate capability(232 mAh·g^(-1)at 2.0 A·g^(-1)).展开更多
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 cha...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%.展开更多
Multichannel audio signal is more difficult to be compressed than mono and stereo ones.A novel multichannel audio signal compression method based on tensor representation and decomposition is proposed in this paper.Th...Multichannel audio signal is more difficult to be compressed than mono and stereo ones.A novel multichannel audio signal compression method based on tensor representation and decomposition is proposed in this paper.The multichannel audio is represented with 3-order tensor space and is decomposed into core tensor with three factor matrices in the way of channel,time and frequency.Only the truncated core tensor is transmitted which will be multiplied by the pre-trained factor matrices to reconstruct the original tensor space.Objective and subjective experiments have been done to show a very noticeable compression capability with an acceptable output quality.The novelty of the proposed compression method is that it enables both high compression capability and backward compatibility with limited signal distortion to the hearing.展开更多
The performance of ALOHA, Non-Persistent CSMA protocols and their slotted versions in Packet Radio Network is analyzed in consideration of the time of propagation delay, the time of radio transformation from receiving...The performance of ALOHA, Non-Persistent CSMA protocols and their slotted versions in Packet Radio Network is analyzed in consideration of the time of propagation delay, the time of radio transformation from receiving state to transmitting state, and the time for the radio to sense the carrier. The analysis shows that these parameters are the main factors deteriorating the performance of the protocols, especially for CSMA. The multichannel mode efficiently decreases the effects of these factors and the system capacity is changeable conveniently. Comparing curves and some simulation results are given.展开更多
基金Supported by the National Natural Science Foundation of China(61231015,61401319)the Natural Science Foundation of Hubei Province(2015CFA061)
文摘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.
文摘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.
文摘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.
基金Key-Area Research and Development Program of Guangdong Province(2019B090915002).
文摘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.
基金supported by the special funds of Laoshan Laboratory(No.LSKJ202203604)the National Key Research and Development Program of China(No.2016 YFC0303901).
文摘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.
文摘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.
基金supported in part by the National Natural Science Foundation of China under Grant 42174164 and Grant 41704132in part by the Key Program of the Joint Fund of the Science,Technology,and Education of Sichuan Province,China under Grant 2024NSFSC1955+4 种基金in part by the Natural Science Foundation of Sichuan Province,China under Grant 2024NSFSC0080in part by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project under Grant SKLGP2022Z011in part by the Chengdu University of Technology Postgraduate Innovative Cultivation Program:Spatiotemporal Characterization of Seismic Signals for Tight Channel Sandstone Gas Reservoirs in the Synchro-Squeezing/Extracting Transform Domain under Grant CDUT2023BJCx002in part by the Creative Research Groups of the Natural Science Foundation of Sichuan under Grant 2023NSFSC198414th Five Year Plan Major Science and Technology Project of CNOOC under Grant KJGG2022-0903.
文摘As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limitation,this paper proposes a multichannel spectral fitting(MSF)method.The MSF method aims to enhance seismic resolution by considering the spectral characteristics and the correlations between adjacent seismic traces.The key to the MSF method involves utilizing the amplitude spectrum of the attenuated Ricker wavelet to construct an objective function for spectral fitting,leading to improved seismic resolution.Furthermore,the MSF method establishes the correlation between adjacent seismic traces as a constraint to stably solve the target parameters based on the entire seismic spectrum,which helps obtain horizontally consistent and more realistic seismic signals.Synthetic and field seismic examples demonstrate that the proposed method not only provides higher-resolution seismic signals but also reveals more fine details of thin reservoirs compared to the time-variant spectral whitening method.It is concluded that the MSF method is a promising tool for seismic signal processing.
基金supported by the Science Center for Gas Turbine Project, China (No. P2022-B-Ⅱ-018-001)。
文摘Enhancing the ignition system performance of turbo engines is crucial,with a focus on rapidly and reliably igniting the entire combustor in low-temperature,low-pressure,high-speed inlet flow conditions.This challenge has garnered international attention.To address the issue of reliable ignition in the combustors of advanced propulsion system,this paper proposes a Multichannel Jet Enhanced Plasma Igniter(MJEPI) and conducts comparative experimental studies with the conventional spark igniter in a component-level dual-dome swirl combustor.The ignition limit in the combustor is obtained and the ignition processes are recorded.Experimental results demonstrate that the MJEPI significantly improves the ignition performance at high altitude.Specifically,at 0 km and 6 km for ground start-up,ignition limit is extended by 36% and 29%,respectively.At 6 km and 12 km for high-altitude relight,ignition limit is extended by 32% and 21%,respectively.The maximum ignition height is increased by 2.3 km,as determined by the global equivalence ratio of 1.The primary reason for these improvements is attributed to the larger initial flame kernel with greater penetration depth generated by MJEPI,which enables it to withstand more sever conditions such as low temperature,low pressure,and poor kerosene spray quality at elevated altitudes.
基金supported by the basic and forward-looking project(No.2023YQX302)。
文摘Traditional deconvolution methods based on single-channel inversion do not consider the spatial structural relation between channels,and hence,they yield high-resolution results with the existing transverse inconsistency or discontinuity.Therefore,in this study,the local dip angle was used to obtain the structural information and construct the spatial structurally constraint operator.This operator is then introduced into multichannel deconvolution as a regularization operator to improve the resolution and maintain the transverse continuity of seismic data.Model tests and actual seismic data processing have demonstrated the effectiveness and practicability of this method.
基金The National Natural Science Foundation of China(No.30900356,81071135)the National High Technology Research and Development Program of China(863Program)(No.2008AA02Z410)
文摘A multichannel matching pursuit（MMP）algorithm is proposed to decompose the one-dimensional multichannel non-stationary magnetoencephalography（MEG）signal at a single-trial level.The single-channel matching pursuit（MP）linearly decomposes the signal into a set of Gabor atoms,which are adaptively chosen from an overcomplete dictionary with good time-frequency characters.The MMP is the extension of the MP,which represents multichannel signals using linear combination of Gabor atoms with the same occurrence,frequency,phase,and time width,but varying amplitude in all channels.The results demonstrate that the MMP can optimally reconstruct the original signal and automatically remove artifact noises.Moreover,the coherence between the 3D source reconstruction and the prior knowledge of psychology further suggests that the MMP is effective in MEG single-trial processing.
基金supported by the National Natural Science Foundation of China(21576298,21425627)the Science and Technology Plan Project of Guangdong Province(2013B090500029)+1 种基金Natural Science Foundation of Guangdong Province(2014A030313135,2014A030308012)the State Key Laboratory of Chemical Resource Engineering(CRE-2015-C-301),China~~
文摘The fabrication of multicomponent heterojunctions is an effective strategy to improve the performance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic performance of ZnO /TiO2 composites by the formation of multichannel charge separated heterojunctions. ZnO /P25 composites were prepared by an incipient wetness impregnation method, and applied for the photocatalytic destruction of gaseous toluene. The ZnO /P25 composites consist of anatase TiO2（ATiO2）, rutile TiO2（RTiO2） and hexagonal zincite structures. The parasitic phase of ZnO in P25 leads to the formation of ZnO（002）/ATiO2（101）/RTiO2（110） heterojunctions that exhibit enhanced light absorption and improved multichannel electron/hole separation. ZnO /P25 heterojunctions can completely oxidize toluene into CO2 and H2O under ultraviolet light irradiation at room temperature, and show enhanced photocatalytic activity in comparison with P25 owing to the efficient electron-hole separation. Such a multichannel charge separated design strategy may provide new insight into the design of highly effective photocatalysts and their potential technological applications.
基金supported by the National Scientific Foundation of China (Grant no. 41506085)the Open Foundation of the Key Laboratory of Gas Hydrate, Ministry of Land and Resources, China (Grant no. SHW [2014]-DX-12)the China Geological Survey Project (Grant no. DD20160213)
文摘When used with large energy sparkers, marine multichannel small-scale high-resolution seismic detection technology has a high resolution, high-detection precision, a wide applicable range, and is very flexible. Positive results have been achieved in submarine geological research, particularly in the investigation of marine gas hydrates. However, the amount of traveltime difference information is reduced for the velocity analysis under conditions of a shorter spread length, thus leading to poorer focusing of the velocity spectrum energy group and a lower accuracy of the velocity analysis. It is thus currently debatable whether the velocity analysis accuracy of short-arrangement multichannel seismic detection technology is able to meet the requirements of practical application in natural gas hydrate exploration. Therefore, in this study the bottom boundary of gas hydrates(Bottom Simulating Reflector, BSR) is used to conduct numerical simulation to discuss the accuracy of the velocity analysis related to such technology. Results show that a higher dominant frequency and smaller sampling interval are not only able to improve the seismic resolution, but they also compensate for the defects of the short-arrangement, thereby improving the accuracy of the velocity analysis. In conclusion, the accuracy of the velocity analysis in this small-scale, high-resolution, multi-channel seismic detection technology meets the requirements of natural gas hydrate exploration.
基金Supported by Ministry of Science and Higher Education,No.FGMF-2022-0005 and No.0410-2020-0007。
文摘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.
文摘Objective： To analyze reflux parameters by means of combined multichannel intraluminal impedance and pH （MII-pH） monitoring in patients with gastroesophageal reflux disease （GERD） symptoms off medication, and to find the reflux characteristics of Chinese GERD patients and the influences of gender, age, body posture, and body mass index （BMI） on gastroesophageal reflux （GER）. Methods： Between Dec. 2008 and May 2014, 125 patients with typical GERD symptoms were subjected to 24-h MII-pH monitoring. Twelve patients with normal MII-pH profiles were not considered for analysis. The reflux parameters of 113 GERD patients with abnormal Mll-pH results were analyzed. Results： （1） DeMeester scores were above the normal range in 46.90% （53/113） of GERD patients. Weakly acidic refluxes were prevalent in GERD patients, and the frequency of abnormal weakly acidic reflux was 75.22% （85/113）. The frequencies of abnormal symptom index （SI） and symptom association probability （SAP） were 19.47% （22/113） and 14.16% （16/113）, respectively. （2） The frequencies of DeMeester scores, the %time at pH〈4, and the numbers of reflux episodes and of long reflux episodes 〉5 min were significantly higher in male patients than in female patients. （3） The %time at pH〈4 was much higher during upright periods than during supine periods. During supine periods, 31.86% （36/113） of GERD patients had delayed bolus clearance time, compared with 19.47% （22/113） during upright periods. （4） The number of abnormal DeMeester scores, %time at pH〈4, and the number of acid refluxes during upright periods were significantly higher in obese GERD patients than in GERD patients with a normal BMI. Over- weight GERD patients also had many more acid refluxes during upright periods than GERD patients with a normal BMI Conclusions： Weakly acidic refluxes were prevalent in Chinese GERD patients. The factors male, gender, upright position, obesity （BMI〉25）, but not age, may increase the frequency and severity of GER.
基金the support from the Fundamental Research Funds for the Central Universities(No.56XIA15003)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institution(PAPD)
文摘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.
基金Supported by the Scientific and Technological Research Council of Turkey,No.106S191-SBAG-3439
文摘AIM To evaluate the agreement of multichannel intraluminal impedance-p H monitoring(MII-p HM) and gastroesophageal reflux scintigraphy(GES) for the diagnosis of gastroesophageal reflux disease. METHODS Seventy-five consecutive patients with suspectedgastroesophageal reflux disease(GERD) underwent 24-h combined MII-p HM recording and one hour radionuclide scintigraphy during the course of the MIIpH M study. Catheters with 6 impedance channels and 1 p H sensor were placed transnasally. Impedance and p H data analysis were performed automatically and manually. For impedance monitoring, reflux was defined as a retrograde 50% drop in impedance, starting distally and propagating retrogradely to at least the next two more proximal measuring channels. Reflux index(RI, percentage of the entire record that esophageal p H is < 4.0) greater than 4.2% for p HM and number of refluxes more than 50 for 24 h for MII were accepted as positive test results. At scintigraphy, 240 frames of 15 seconds duration were acquired in the supine position. Gastroesophageal reflux was defined as at least one reflux episode in the esophagus. After scintigraphic evaluation, impedance-pH recordings and scintigraphic images were evaluated together and agreement between tests were evaluated with Cohen's kappa.RESULTS Sufficient data was obtained from 60(80%) patients(34 male, 56.7%) with a mean age of 8.7 ± 3.7 years(range: 2.5-17.3 years; median: 8.5 years). Chronic cough, nausea, regurgitation and vomiting were the most frequent symptoms. The mean time for recording of MII-pH M was 22.8 ± 2.4 h(range: 16-30 h; median: 22.7 h). At least one test was positive in 57(95%) patients. According to diagnostic criteria, GERD was diagnosed in 34(57.7%), 44(73.3%), 47(78.3%) and 51(85%) patients by means of p HM, MII, GES and MII-p HM, respectively. The observed percentage agreements/κ values for GES and p HM, GES and MII, GES and MII-p HM, and MII and p HM are 48.3%/-0.118; 61.7%/-0.042; 73.3%/0.116 and 60%/0.147, respectively. There was no or slight agreement between GES and p HM alone, MII alone or MII-p HM. p H monitoring alone missed 17 patients compared to combined MII-p HM. The addition of MII to pH monitoring increased the diagnosis rate by 50%.CONCLUSION No or slight agreement was found among p H monitoring, MII monitoring, MII-pH monitoring and GES for the diagnosis of gastroesophageal reflux disease.
基金financially supported by a National Research Foundation of Korea(NRF)from the Korean government(MSIT)(No.2020R1C1C1003375)。
文摘Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low cost.Nevertheless,the difficulty in finding appropriate electrode materials that can efficiently store the larger K ions has hindered their practical application.Herein,we report a novel anode material,N-doped multichannel carbon nanofibers embedded with porous CoS nanoprisms(CSP@NMCNF),for high-performance PIBs.The CSP@NMCNF was synthesized using a two-step strategy comprising of the electrospinning of Co acetate hydroxide nanoprism/binary polymer blend and a subsequent heat treatment.The porous CoS nanoprisms with an anisotropic morphology were well aligned along the length axis of the N-doped multichannel carbon nanofibers,thus ensuring their structural stability during the repeated charge-discharge process.In addition,numerous pores facilitated the transport of electrons and ions.Accordingly,the CSP@NMCNF anode exhibited excellent electrochemical performance,delivering a high specific capacity of 368 mAh·g^(-1)at 0.5 A·g^(-1)after 200 cycles and excellent rate capability(232 mAh·g^(-1)at 2.0 A·g^(-1)).
基金National Natural Science Foundation of China(Grant No.91641204).
文摘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%.
基金This work was partially supported by the National Natural Science Foundation of China under Grants No.11161140319,No.61001188，the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20101101110020，the Fund for Basic Research from Beijing Institute of Technology under Grant No.20120542011，the Fund for Beijing Higher Education Young Elite Teacher Project under Grant No.YETP1202
文摘Multichannel audio signal is more difficult to be compressed than mono and stereo ones.A novel multichannel audio signal compression method based on tensor representation and decomposition is proposed in this paper.The multichannel audio is represented with 3-order tensor space and is decomposed into core tensor with three factor matrices in the way of channel,time and frequency.Only the truncated core tensor is transmitted which will be multiplied by the pre-trained factor matrices to reconstruct the original tensor space.Objective and subjective experiments have been done to show a very noticeable compression capability with an acceptable output quality.The novelty of the proposed compression method is that it enables both high compression capability and backward compatibility with limited signal distortion to the hearing.
文摘The performance of ALOHA, Non-Persistent CSMA protocols and their slotted versions in Packet Radio Network is analyzed in consideration of the time of propagation delay, the time of radio transformation from receiving state to transmitting state, and the time for the radio to sense the carrier. The analysis shows that these parameters are the main factors deteriorating the performance of the protocols, especially for CSMA. The multichannel mode efficiently decreases the effects of these factors and the system capacity is changeable conveniently. Comparing curves and some simulation results are given.
