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
Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf（n=4- 23）J^π -（7/2）° of scandium at different levels of approximation within the fram...Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf（n=4- 23）J^π -（7/2）° of scandium at different levels of approximation within the framework of multichannel quantum defect theory. The present results show that the dipole polarizations play an important role. Considering the dynamical dipole polarization effects, this paper finds that the difference between calculated and experimental quantum defects for the 4s^2nf（n=4- 23）J^π -（7/2）° series is generally about 0.01- 0.03. Furthermore, the reason that 4s^216f is obscured in experimental spectra is suggested to be the interaction with the neighbouring resonance state converged to 3d^2（^1G4） of Sc^＋.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
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
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
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
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
Relighting of jet engines at high altitudes is very difficult because of the high velocity, low pressure, and low tempera- ture of the inlet airflow. Successful ignition needs sufficient ignition energy to generate a ...Relighting of jet engines at high altitudes is very difficult because of the high velocity, low pressure, and low tempera- ture of the inlet airflow. Successful ignition needs sufficient ignition energy to generate a spark kernel to induce a so-called critical flame initiation radius. However, at high altitudes with high-speed inlet airflow, the critical flame initiation radius becomes larger; therefore, traditional ignition technologies such as a semiconductor igniter （SI） become infeasible for use in high-altitude relighting of jet engines. In this study, to generate a large spark kernel to achieve successful ignition with high-speed inlet airflow, a new type of multichannel plasma igniter （MCPI） is proposed. Experiments on the electrical char- acteristics of the MCPI and SI were conducted under normal and sub-atmospheric pressures （P = 10-100 kPa）. Ignition experiments for the MCPI and SI with a kerosene/air mixture in a triple-swirler combustor under different velocities of inlet airflow （60-110 m/s）, with a temperature of 473 K at standard atmospheric pressure, were investigated. Results show that the MCPI generates much more arc discharge energy than the SI under a constant pressure; for example, the MCPI generated 6.93% and 16.05 % more arc discharge energy than that of the SI at 30 kPa and 50 kPa, respectively. Compared to the SI, the MCPI generates a larger area and height of plasma heating zone, and induces a much larger initial spark kernel. Furthermore, the lean ignition limit of the MCPI and SI decreases with an increase in the velocity of the inlet airflow, and the maximum velocity of inlet airflow where the SI and MCPI can achieve successful and reliable ignition is 88.7 m/s and 102.2 m/s, respectively. Therefore, the MCPI has the advantage of achieving successful ignition with high-speed inlet airflow and extends the average ignition speed boundary of the kerosene/air mixture by 15.2%.展开更多
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 characterizi...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.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
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 qual...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.展开更多
Abstract This paper aims at the multichannel synthetic aperture radar （SAR） image speckle reduc- tion. This paper proposes a novel energy minimized regularization model for multichannel image denoising, which is an ...Abstract This paper aims at the multichannel synthetic aperture radar （SAR） image speckle reduc- tion. This paper proposes a novel energy minimized regularization model for multichannel image denoising, which is an extension of the non-local total variational model for gray-scale image. It contains two terms, namely the vectorial data fidelity term and the non-local vectorial total variation term. The latter is constructed by high-dimensional non-local gradient that contains the structure information of the multichannel image. The existence and the uniqueness of the solution of the model are proved. A fixed point iterative algorithm is designed to acquire the solution of this model. The convergence property of this algorithm is proved as well. This model is applied to the multipolarimetric and multi-temporal RAI）ARSAT-2 images despeckling. The result shows that this model performs better than the original vectorial total variational model on texture preserving.展开更多
The effectiveness of eliminating the noises in short-period data of geomagnetic intensity recorded in a little seismo-geomagnetic array by using numerical multichannel predictive filtering has been studied. The result...The effectiveness of eliminating the noises in short-period data of geomagnetic intensity recorded in a little seismo-geomagnetic array by using numerical multichannel predictive filtering has been studied. The result shows that this technique is effective to fit external magnetic disturbance to inner electromagnetic induced difference field and reduce the noise level of difference data successfully. The filter quality factor Q of two examples in this work are 0. 86 and 0.68 respectively. The spectral analysis shows that during geomagnetic-calm days the fourfold-frequency harmonics of S q in difference data are main components. The length of the optimum filter depends on not only the frequency of predicable energy in difference data but also maybe the phase difference between input and expected output data. It is difficult to obtain the filter fitting both the data during magnetic-disturbed days and calm days. The result shows that the conductivity in Yanqing-Huailai basin west to Beijing may be much non-uniform.展开更多
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Project supported by the National Natural Science Foundation of China (Grant No 10574162)partial supported from the Scientific Research Fund of GUCAS (Grant No 055101BM03)
文摘Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf（n=4- 23）J^π -（7/2）° of scandium at different levels of approximation within the framework of multichannel quantum defect theory. The present results show that the dipole polarizations play an important role. Considering the dynamical dipole polarization effects, this paper finds that the difference between calculated and experimental quantum defects for the 4s^2nf（n=4- 23）J^π -（7/2）° series is generally about 0.01- 0.03. Furthermore, the reason that 4s^216f is obscured in experimental spectra is suggested to be the interaction with the neighbouring resonance state converged to 3d^2（^1G4） of Sc^＋.
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 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.
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.
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Project supported by the National Natural Science Foundation of China(Grant Nos.91541120,11472306,51336011,and 91641204)
文摘Relighting of jet engines at high altitudes is very difficult because of the high velocity, low pressure, and low tempera- ture of the inlet airflow. Successful ignition needs sufficient ignition energy to generate a spark kernel to induce a so-called critical flame initiation radius. However, at high altitudes with high-speed inlet airflow, the critical flame initiation radius becomes larger; therefore, traditional ignition technologies such as a semiconductor igniter （SI） become infeasible for use in high-altitude relighting of jet engines. In this study, to generate a large spark kernel to achieve successful ignition with high-speed inlet airflow, a new type of multichannel plasma igniter （MCPI） is proposed. Experiments on the electrical char- acteristics of the MCPI and SI were conducted under normal and sub-atmospheric pressures （P = 10-100 kPa）. Ignition experiments for the MCPI and SI with a kerosene/air mixture in a triple-swirler combustor under different velocities of inlet airflow （60-110 m/s）, with a temperature of 473 K at standard atmospheric pressure, were investigated. Results show that the MCPI generates much more arc discharge energy than the SI under a constant pressure; for example, the MCPI generated 6.93% and 16.05 % more arc discharge energy than that of the SI at 30 kPa and 50 kPa, respectively. Compared to the SI, the MCPI generates a larger area and height of plasma heating zone, and induces a much larger initial spark kernel. Furthermore, the lean ignition limit of the MCPI and SI decreases with an increase in the velocity of the inlet airflow, and the maximum velocity of inlet airflow where the SI and MCPI can achieve successful and reliable ignition is 88.7 m/s and 102.2 m/s, respectively. Therefore, the MCPI has the advantage of achieving successful ignition with high-speed inlet airflow and extends the average ignition speed boundary of the kerosene/air mixture by 15.2%.
基金supported by Research Project of Science Fund No. 01-01-02-SF0338Science Fund No.01-01-02-SF0681 from Ministry of Science, Technologyand Innovation of Malaysia
文摘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.
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.
基金supported by the National Natural Science Foundation of China(Nos.61072142,61271437,61201337)the Science Research Project of National University of Defense Technology of China(Nos.JC12-02-05,JC13-02-03)
文摘Abstract This paper aims at the multichannel synthetic aperture radar （SAR） image speckle reduc- tion. This paper proposes a novel energy minimized regularization model for multichannel image denoising, which is an extension of the non-local total variational model for gray-scale image. It contains two terms, namely the vectorial data fidelity term and the non-local vectorial total variation term. The latter is constructed by high-dimensional non-local gradient that contains the structure information of the multichannel image. The existence and the uniqueness of the solution of the model are proved. A fixed point iterative algorithm is designed to acquire the solution of this model. The convergence property of this algorithm is proved as well. This model is applied to the multipolarimetric and multi-temporal RAI）ARSAT-2 images despeckling. The result shows that this model performs better than the original vectorial total variational model on texture preserving.
文摘The effectiveness of eliminating the noises in short-period data of geomagnetic intensity recorded in a little seismo-geomagnetic array by using numerical multichannel predictive filtering has been studied. The result shows that this technique is effective to fit external magnetic disturbance to inner electromagnetic induced difference field and reduce the noise level of difference data successfully. The filter quality factor Q of two examples in this work are 0. 86 and 0.68 respectively. The spectral analysis shows that during geomagnetic-calm days the fourfold-frequency harmonics of S q in difference data are main components. The length of the optimum filter depends on not only the frequency of predicable energy in difference data but also maybe the phase difference between input and expected output data. It is difficult to obtain the filter fitting both the data during magnetic-disturbed days and calm days. The result shows that the conductivity in Yanqing-Huailai basin west to Beijing may be much non-uniform.
