[Objective] The research aimed to study the reproductive health of breed- ing bull after infecting Mycoplasma wenyoniL [Method] The blood and semen quality of breeding bull before and after drug treatment was studied ...[Objective] The research aimed to study the reproductive health of breed- ing bull after infecting Mycoplasma wenyoniL [Method] The blood and semen quality of breeding bull before and after drug treatment was studied by the methods of blood routine examination and breeding soundness examination （BSE）. [Result] Be- fore the treatment with primaquine phosphate, slight anaemia was seen in diseased bull and a lot of M.wenyonfi were seen on blood smears. The scrotal wall of dis- eased bull swelled, testis was softened, the semen quality was reduced, semen quality was decreased and the proportion of primary and secondary deformed sperms was increased. After drug treatment, M.wenyonfi quickly disappeared from blood and the clinical systems were gradually alleviated, so BSE of breeding bulls after one month was passed. [Conclusion] The research laid the foundation for fur- ther study on the relationship between M.wenyonfi and the reduction of bull＇s repro- ductive functions.展开更多
The results of investigation to assess the possibility of copper slag with high MgO to be used as a mineral admixture in concrete were reported in this study. The soundness of cement paste containing the slag has been...The results of investigation to assess the possibility of copper slag with high MgO to be used as a mineral admixture in concrete were reported in this study. The soundness of cement paste containing the slag has been examined by autoclave test. Pozzolanic activity of the slag was studied in comparison to fly ash. The slag was mixed calcium hydroxide and water,and the progress of the pozzolanic reaction was determined by X-ray diffraction,differential thermal analysis-thermogravimetry and scanning electron microscopy from 28 to 90 d. The experimental results showed that the autoclave expansion value of cement paste containing the slag was far below the expansion limit (0.8%). It can be conclude that the slag has little periclase content. The consumption of calcium hydroxide showed the slag exhibits high pozzolanic activity,which was higher than that of fly ash. Hence,use of the copper slag with high MgO but low periclase content as a mineral admixture in concrete seems feasible.展开更多
Workflow management systems are widely used in improving the efficiency of business processes. To develop a workflow management system is the key to workflow modeling. In this paper, the compositional time net is pres...Workflow management systems are widely used in improving the efficiency of business processes. To develop a workflow management system is the key to workflow modeling. In this paper, the compositional time net is presented to model workflow processes on the basis of the analyzing methods of time Petri nets and workflows, and to describe the static relationships and the dynamic semantics of the task of multiple workflow com- position. The paper puts more emphasis on checking the sotmdness of composed workflow, at the same time, combinational problems of non-conditional structure of the compositional time net are introduced and analyzed. A sufficient and necessary condition for determining the soundness of compositional nets is obtained.展开更多
The physical and chemical properties and soundness of Baosteel Power Plant＇ s dry desulphurized fly ash were systematically investigated and compared with those of the similar byproducts produced by some other domest...The physical and chemical properties and soundness of Baosteel Power Plant＇ s dry desulphurized fly ash were systematically investigated and compared with those of the similar byproducts produced by some other domestic power plants. The feasibility of these byproducts used as a construction material was also analyzed. The results show that Baosteel＇s dry desulphurized fly ash is a kind of ash with high calcium and high sulfur contents, which has the characteristics of volcanic ash activity. It contains sulfate and sulfite, and is easy to cause sulfate activation. It has higher activity compared with common fly ash. But higher calcium sulfite and free-CaO contents in ash will bring about soundness concerns to users. Therefore, quality tests and volume control will be necessary when fly ash is used as a construction material.展开更多
Ⅰ. INTRODUCTIONThis note presents the semantic interpretation of predicate calculus system withequality symbol "=" of medium logic M E~* and its Soundness, Completeness, and Compact Theorem. In view of the ...Ⅰ. INTRODUCTIONThis note presents the semantic interpretation of predicate calculus system withequality symbol "=" of medium logic M E~* and its Soundness, Completeness, and Compact Theorem. In view of the characteristic of M E~*, when we construct展开更多
Kapur and Musser studied the theoretical basis for proof by consistency and ob-tained an inductive completeness result: p q if and only if p = q is true in everyinductive model. However, there is a loophole in their p...Kapur and Musser studied the theoretical basis for proof by consistency and ob-tained an inductive completeness result: p q if and only if p = q is true in everyinductive model. However, there is a loophole in their proof for the soundness part:p = q implies p = q is true in every inductive model. The aim of this paper is to give acorrect characterization of inductive soundness from an algebraic view by introducingstrong inductive models.展开更多
Salzburg is a beautiful city in Austria.It has old buildings,pretty streets and big mountains all around.The scenery is amazing!The famous movie The Sound of Music was filmed there.Many people visit Salzburg to see th...Salzburg is a beautiful city in Austria.It has old buildings,pretty streets and big mountains all around.The scenery is amazing!The famous movie The Sound of Music was filmed there.Many people visit Salzburg to see the locations from the movie.Some even do interviews there to ask people their feelings about the movie.One famous location from the movie is the Mirabell Gardens.The actors sang the song"Do-Re-Mi"there.The gardens have colorful flowers,statues and fountains.Salzburg is a fun and exciting place to visit and explore.展开更多
Background and Objectives:The perception of sound in the vertical plane supports spatial hearing by enabling listeners to detect sources located above and below.Sounds originating from both the front and back elevatio...Background and Objectives:The perception of sound in the vertical plane supports spatial hearing by enabling listeners to detect sources located above and below.Sounds originating from both the front and back elevations along the mid-sagittal plane further contribute to a three-dimensional auditory experience.This study aimed to characterize the variability in vertical sound localization abilities among normal-hearing(NH)individuals using spatialized audio.Materials and Methods:Fifty-one NH participants(aged 18 to 35 years)completed three vertical localization tasks under headphones as part of a single-group,within-subject experimental study.These tasks included two-plane identification:(1)top-down localization,(2)front-back localization,and one discrimination task in the front plane.Hierarchical Cluster Analysis(HCA)was employed to identify distinct patterns in spatial localization profiles specific to the vertical-median plane.Fisher's Discriminant Function Analysis(FDA)was used to validate the accuracy of HCA and estimate classification error.Results:HCA revealed three distinct listener clusters:(1)cluster 1 with good performance across all three tasks,(2)cluster 2 with selective impairment in top-bottom identification,and(3)cluster 3 with selective deficits in front-back identification.FDA validated group membership of the clusters identified by the HCA,with a prediction accuracy of 98%.Conclusions:Individuals with clinically NH exhibited three distinct vertical localization profiles:uniform performers,those impaired in top-bottom identification,and those impaired in front-back identification.These profiles may be linked to the interplay between acoustic and non-acoustic perceptual factors.展开更多
Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at ...Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.展开更多
This paper proposes two types of integrated sound absorbing-insulating metamaterials with low thickness and efficient sound attenuation in the low-frequency bandwidth,i.e.,labyrinth-type metamaterial and multi-order r...This paper proposes two types of integrated sound absorbing-insulating metamaterials with low thickness and efficient sound attenuation in the low-frequency bandwidth,i.e.,labyrinth-type metamaterial and multi-order resonator metamaterial.The labyrinth-type metamaterial is designed through spatial dimension transfer,transferring the required dimension in the thickness direction to the planar thin layer.Based on the Helmholtz resonance,the metamaterial achieves noise reduction through the reflection of sound waves and the thermoviscous dissipation of holes and cavities.This mechanism enables its sound insulation performance to produce the same gain effect as absorption,thereby accomplishing the broadband absorbing-insulating integrated design.With a thickness of only 33 mm,it achieves both sound absorption and insulation effects over more than one octave.The multi-order resonator metamaterial has a larger working bandwidth than the labyrinth-type metamaterial.It is designed based on the multiorder resonance absorption mechanism,and consists of 9 different orders of resonator units.The metamaterial obtains a continuous sound absorption coefficient curve in the low-frequency range of 362–1712 Hz,and possesses high transmission loss(TL)above 346 Hz.In addition,this paper deeply explores the sound absorbing-insulating mechanism through the correlation analysis between the sound absorption coefficient and TL curves.The experimental results verify the continuous and efficient absorption effects of the two metamaterials,as well as their insulation performance that breaks the mass law.In low-frequency engineering applications,the two designed metamaterials demonstrate great potential and value at sub-wavelength dimensions.展开更多
In ultrasonic non-destructive testing of high-temperature industrial equipment,sound velocity drift induced by non-uniform temperature fields can severely compromise defect localization accuracy.Conventional approache...In ultrasonic non-destructive testing of high-temperature industrial equipment,sound velocity drift induced by non-uniform temperature fields can severely compromise defect localization accuracy.Conventional approaches that rely on room-temperature sound velocities introduce systematic errors,potentially leading to misjudgment of safety-critical components.Two primary challenges hinder current methods:first,it is difficult to monitor real-time changes in sound velocity distribution within a thermal gradient;second,traditional uniform-temperature correction models fail to capture the nonlinear dependence of material properties on temperature and their effect on ultrasonic velocity fields.Here,we propose a defect localization correction method based on multiphysics coupling.A two-dimensional coupled heat transfer–wave propagation model is established in COMSOL,and a one-dimensional steady-state heat transfer condition is used to design a numerical pulse–echo experiment in 1020 steel.Temperature-dependent material properties are incorporated,and the intrinsic relationship between sound velocity and temperature is derived,confirming consistency with classical theories.To account for gradient temperature fields,a micro-element integration algorithm discretizes the propagation path into segments,each associated with a locally computed temperature from the steady-state heat conduction solution.Defect positions are dynamically corrected through cumulative displacement along the propagation path.By integrating heat conduction and elastic wave propagation in a multiphysics framework,this method overcomes the limitations of uniform-temperature assumptions.The micro-element integration approach enables dynamic tracking of spatially varying sound velocities,offering a robust strategy to enhance ultrasonic testing accuracy in high-temperature industrial environments.展开更多
This study investigates the effects of ocean boundaries on modal shapes in very-low-frequency(VLF,1–10 Hz)sound propagation through the deep ocean.Utilizing a normal mode solution formulated in terms of parabolic cyl...This study investigates the effects of ocean boundaries on modal shapes in very-low-frequency(VLF,1–10 Hz)sound propagation through the deep ocean.Utilizing a normal mode solution formulated in terms of parabolic cylinder functions(PCF),we demonstrate that boundary interactions induce a phase change reduction below-πat frequencies of several hertz.This reduction,in turn,forces a key transition in the solution,shifting the order of the PCF from integer to non-integer values.Analysis of the characteristic shape of the PCF versus its order reveals that these boundary-influenced modes exhibit an energy shift toward deeper regions and a weakened axial convergence of the underwater sound field.展开更多
China’s annual Central Economic Work Conference, which ended in Beijing on December 7, emphasized that the country should give priority to the soundness of economic operations instead of the growth rate in the future...China’s annual Central Economic Work Conference, which ended in Beijing on December 7, emphasized that the country should give priority to the soundness of economic operations instead of the growth rate in the future. Comparing the quality-first approach with the previous focus on GDP growth, a Xinhua News Agency commentary hails the adjustment as a significant change in the development strategy of the country.展开更多
The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-...The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.展开更多
Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter...Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter.Therefore,the need to monitor disc cutter wear in real-time has emerged as a technical challenge for TBMs.In this study,real-time disc cutter wear monitoring is developed based on sound and vibration sensors.For this purpose,the microphone and accelerometer were used to record the sound and vibration signals of cutting three different types of rocks with varying abrasions on a laboratory scale.The relationship between disc cutter wear and the sound and vibration signal was determined by comparing the measurements of disc cutter wear with the signal plots for each sample.The features extracted from the signals showed that the sound and vibration signals are impacted by the progression of disc wear during the rock-cutting process.The signal features obtained from the rock-cutting operation were utilized to verify the machine learning techniques.The results showed that the multilayer perceptron(MLP),random subspace-based decision tree(RS-DT),DT,and random forest(RF)methods could predict the wear level of the disc cutter with an accuracy of 0.89,0.951,0.951,and 0.927,respectively.Based on the accuracy of the models and the confusion matrix,it was found that the RS-DT model has the best estimate for predicting the level of disc wear.This research has developed a method that can potentially determine when to replace a tool and assess disc wear in real-time.展开更多
Metal foams are a fascinating group of materials that possess distinct physicochEMIcal properties and interconnected strut features with high surface area-to-volume ratios, high specific strength and lightweight natur...Metal foams are a fascinating group of materials that possess distinct physicochEMIcal properties and interconnected strut features with high surface area-to-volume ratios, high specific strength and lightweight nature. These characteristics make them ideal for applications in vibration damping, heat insulation and weight reduction. In recent years, there has been increasing interest in the application of interfering energy conversion such as electromagnetic wave (EMW) and sound, where the metal foams could emerge as a solution. This paper will present a comprehensive review of the preparation methods as well as the interference energy converting mechanisms for metal foams. Typically, the progress and prospective aspects of metal foams for EMW absorption, electromagnetic interference (EMI) shielding and sound absorption have been emphasized. Through this review, we aspire to offer valuable insights for the development of multifunctional applications with metal foam materials.展开更多
This review provides a comprehensive overview of natural rubber(NR)composites,focusing on their properties,compounding aspects,and renewable practices involving natural fibre reinforcement.The properties of NR are inf...This review provides a comprehensive overview of natural rubber(NR)composites,focusing on their properties,compounding aspects,and renewable practices involving natural fibre reinforcement.The properties of NR are influenced by the compounding process,which incorporates ingredients such as elastomers,vulcanizing agents,accelerators,activators,and fillers like carbon black and silica.While effective in enhancing properties,these fillers lack biodegradability,prompting the exploration of sustainable alternatives.The potential of natural fibres as renewable reinforcements in NR composites is thoroughly covered in this review,highlighting both their advan-tages,such as improved sustainability,and the challenges they present,such as compatibility with the rubber matrix.Surface treatment methods,including alkali and silane treatments,are also discussed as solutions to improve fibre-matrix adhesion and mitigate these challenges.Additionally,the review highlights the potential of oil palm empty fruit bunch(EFB)fibres as a natural fibre reinforcement.The abundance of EFB fibres and their alignment with sustainable practices make them promising substitutes for conventional fillers,contributing to valuable knowledge and supporting the broader move towards renewable reinforcement to improve sustain-ability without compromising the key properties of rubber composites.展开更多
Ultrasound computed tomography(USCT)is a noninvasive biomedical imaging modality that offers insights into acoustic properties such as the sound speed(SS)and acoustic attenuation(AA)of the human body,enhancing diagnos...Ultrasound computed tomography(USCT)is a noninvasive biomedical imaging modality that offers insights into acoustic properties such as the sound speed(SS)and acoustic attenuation(AA)of the human body,enhancing diagnostic accuracy and therapy planning.Full waveform inversion(FWI)is a promising USCT image reconstruction method that optimizes the parameter fields of a wave propagation model via gradient-based optimization.However,twodimensional FWI methods are limited by their inability to account for three-dimensional wave propagation in the elevation direction,resulting in image artifacts.To address this problem,we propose a three-dimensional time-domain full waveform inversion algorithm to reconstruct the SS and AA distributions on the basis of a fractional Laplacian wave equation,adjoint field formulation,and gradient descent optimization.Validated by two sets of simulations,the proposed algorithm has potential for generating high-resolution and quantitative SS and AA distributions.This approach holds promise for clinical USCT applications,assisting early disease detection,precise abnormality localization,and optimized treatment planning,thus contributing to better healthcare outcomes.展开更多
Objective:To explore the research landscape and hotspots of Computerized Respiratory Sound Analysis(CORSA)and provide a reference for future in-depth studies.Methods:Literature related to CORSA published up to August ...Objective:To explore the research landscape and hotspots of Computerized Respiratory Sound Analysis(CORSA)and provide a reference for future in-depth studies.Methods:Literature related to CORSA published up to August 27,2020,was retrieved from the Web of Science Core Collection.CiteSpace 5.6.R3 was used to perform co-authorship analysis,institutional collaboration analysis,keyword co-occurrence analysis,and co-citation analysis.Results:A total of 1,897 publications were included.Co-authorship analysis identified several influential contributors,including Zahra Moussavi,Kenneth Sundaraj,and H.Pasterkamp.Major research institutions included the University of Manitoba,the University of Queensland,and Aristotle University of Thessaloniki.Keyword co-occurrence analysis indicated that“respiratory sound,”“lung sound,”“asthma,”“children,”and“classification”were major research themes.The most frequently co-cited articles were published by Arati Gurung(2011),Mohammed Bahoura(2009),and H.Pasterkamp(1997).Highly cited journals included Chest,the American Journal of Respiratory and Critical Care Medicine,and IEEE Transactions on Biomedical Engineering.Conclusion:CORSA research is primarily driven by European and North American scholars and institutions,with China still in an early stage of development.Current hotspots include respiratory sound acquisition and processing,feature extraction methods such as Mel-frequency cepstral coefficients(MFCCs),and classification techniques based on machine learning and deep learning.CORSA is suitable for diverse populations and is widely applied in respiratory diseases,especially bronchial asthma.Its non-invasive nature offers particular advantages for infants and pregnant women.Although CORSA demonstrates strong clinical potential,its clinical translation remains limited.Advancing clinical applications and bridging the gap between research and practice will be key directions for future development.The prominence of top-tier respiratory and engineering journals among citations suggests that CORSA is an emerging and influential research frontier.展开更多
基金Supported by Spark Program of Ministry of Science and Technology(2012GA6200025)Science and Technology Development Plan Program in Shijiazhuang City(08150132A-3)Program of Qinhuangdao Science and Technology Bureau(200901A070)~~
文摘[Objective] The research aimed to study the reproductive health of breed- ing bull after infecting Mycoplasma wenyoniL [Method] The blood and semen quality of breeding bull before and after drug treatment was studied by the methods of blood routine examination and breeding soundness examination （BSE）. [Result] Be- fore the treatment with primaquine phosphate, slight anaemia was seen in diseased bull and a lot of M.wenyonfi were seen on blood smears. The scrotal wall of dis- eased bull swelled, testis was softened, the semen quality was reduced, semen quality was decreased and the proportion of primary and secondary deformed sperms was increased. After drug treatment, M.wenyonfi quickly disappeared from blood and the clinical systems were gradually alleviated, so BSE of breeding bulls after one month was passed. [Conclusion] The research laid the foundation for fur- ther study on the relationship between M.wenyonfi and the reduction of bull＇s repro- ductive functions.
文摘The results of investigation to assess the possibility of copper slag with high MgO to be used as a mineral admixture in concrete were reported in this study. The soundness of cement paste containing the slag has been examined by autoclave test. Pozzolanic activity of the slag was studied in comparison to fly ash. The slag was mixed calcium hydroxide and water,and the progress of the pozzolanic reaction was determined by X-ray diffraction,differential thermal analysis-thermogravimetry and scanning electron microscopy from 28 to 90 d. The experimental results showed that the autoclave expansion value of cement paste containing the slag was far below the expansion limit (0.8%). It can be conclude that the slag has little periclase content. The consumption of calcium hydroxide showed the slag exhibits high pozzolanic activity,which was higher than that of fly ash. Hence,use of the copper slag with high MgO but low periclase content as a mineral admixture in concrete seems feasible.
基金Supported by the National Natural Science Foundation of China (61103115)the Key Project of Guangdong and Hong Kong (2007A090601001)
文摘Workflow management systems are widely used in improving the efficiency of business processes. To develop a workflow management system is the key to workflow modeling. In this paper, the compositional time net is presented to model workflow processes on the basis of the analyzing methods of time Petri nets and workflows, and to describe the static relationships and the dynamic semantics of the task of multiple workflow com- position. The paper puts more emphasis on checking the sotmdness of composed workflow, at the same time, combinational problems of non-conditional structure of the compositional time net are introduced and analyzed. A sufficient and necessary condition for determining the soundness of compositional nets is obtained.
文摘The physical and chemical properties and soundness of Baosteel Power Plant＇ s dry desulphurized fly ash were systematically investigated and compared with those of the similar byproducts produced by some other domestic power plants. The feasibility of these byproducts used as a construction material was also analyzed. The results show that Baosteel＇s dry desulphurized fly ash is a kind of ash with high calcium and high sulfur contents, which has the characteristics of volcanic ash activity. It contains sulfate and sulfite, and is easy to cause sulfate activation. It has higher activity compared with common fly ash. But higher calcium sulfite and free-CaO contents in ash will bring about soundness concerns to users. Therefore, quality tests and volume control will be necessary when fly ash is used as a construction material.
文摘Ⅰ. INTRODUCTIONThis note presents the semantic interpretation of predicate calculus system withequality symbol "=" of medium logic M E~* and its Soundness, Completeness, and Compact Theorem. In view of the characteristic of M E~*, when we construct
文摘Kapur and Musser studied the theoretical basis for proof by consistency and ob-tained an inductive completeness result: p q if and only if p = q is true in everyinductive model. However, there is a loophole in their proof for the soundness part:p = q implies p = q is true in every inductive model. The aim of this paper is to give acorrect characterization of inductive soundness from an algebraic view by introducingstrong inductive models.
文摘Salzburg is a beautiful city in Austria.It has old buildings,pretty streets and big mountains all around.The scenery is amazing!The famous movie The Sound of Music was filmed there.Many people visit Salzburg to see the locations from the movie.Some even do interviews there to ask people their feelings about the movie.One famous location from the movie is the Mirabell Gardens.The actors sang the song"Do-Re-Mi"there.The gardens have colorful flowers,statues and fountains.Salzburg is a fun and exciting place to visit and explore.
文摘Background and Objectives:The perception of sound in the vertical plane supports spatial hearing by enabling listeners to detect sources located above and below.Sounds originating from both the front and back elevations along the mid-sagittal plane further contribute to a three-dimensional auditory experience.This study aimed to characterize the variability in vertical sound localization abilities among normal-hearing(NH)individuals using spatialized audio.Materials and Methods:Fifty-one NH participants(aged 18 to 35 years)completed three vertical localization tasks under headphones as part of a single-group,within-subject experimental study.These tasks included two-plane identification:(1)top-down localization,(2)front-back localization,and one discrimination task in the front plane.Hierarchical Cluster Analysis(HCA)was employed to identify distinct patterns in spatial localization profiles specific to the vertical-median plane.Fisher's Discriminant Function Analysis(FDA)was used to validate the accuracy of HCA and estimate classification error.Results:HCA revealed three distinct listener clusters:(1)cluster 1 with good performance across all three tasks,(2)cluster 2 with selective impairment in top-bottom identification,and(3)cluster 3 with selective deficits in front-back identification.FDA validated group membership of the clusters identified by the HCA,with a prediction accuracy of 98%.Conclusions:Individuals with clinically NH exhibited three distinct vertical localization profiles:uniform performers,those impaired in top-bottom identification,and those impaired in front-back identification.These profiles may be linked to the interplay between acoustic and non-acoustic perceptual factors.
基金supported by the Shenzhen Stability Support Plan(Grant No.20231122095154003)National Natural Science Foundation of China(Grant Nos.51978671 and 52422807).
文摘Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.
基金Project supported by the National Natural Science Foundation of China(No.52250287)the Outstanding Youth Science Fund Project of Shaanxi Province of China(No.2024JC-JCQN-49)。
文摘This paper proposes two types of integrated sound absorbing-insulating metamaterials with low thickness and efficient sound attenuation in the low-frequency bandwidth,i.e.,labyrinth-type metamaterial and multi-order resonator metamaterial.The labyrinth-type metamaterial is designed through spatial dimension transfer,transferring the required dimension in the thickness direction to the planar thin layer.Based on the Helmholtz resonance,the metamaterial achieves noise reduction through the reflection of sound waves and the thermoviscous dissipation of holes and cavities.This mechanism enables its sound insulation performance to produce the same gain effect as absorption,thereby accomplishing the broadband absorbing-insulating integrated design.With a thickness of only 33 mm,it achieves both sound absorption and insulation effects over more than one octave.The multi-order resonator metamaterial has a larger working bandwidth than the labyrinth-type metamaterial.It is designed based on the multiorder resonance absorption mechanism,and consists of 9 different orders of resonator units.The metamaterial obtains a continuous sound absorption coefficient curve in the low-frequency range of 362–1712 Hz,and possesses high transmission loss(TL)above 346 Hz.In addition,this paper deeply explores the sound absorbing-insulating mechanism through the correlation analysis between the sound absorption coefficient and TL curves.The experimental results verify the continuous and efficient absorption effects of the two metamaterials,as well as their insulation performance that breaks the mass law.In low-frequency engineering applications,the two designed metamaterials demonstrate great potential and value at sub-wavelength dimensions.
基金supported by the following projects:National Natural Science Foundation of China[U24A20135]Science and Technology Program of the State Administration for Market Regulation[2024MK016]+9 种基金Basic Scientific Research Fund Project for Higher Education Institutions of Inner Mongolia(2024YXXS057)Key Project of Natural Science Foundation of Inner Mongolia[2023ZD12]2023 Inner Mongolia Autonomous Region Key R&D and Achievement Transformation Program[2023YFHH0090]Natural Science Foundation of Inner Mongolia[2022MS05006]Talent Development Fund of Inner Mongolia Autonomous RegionFundamental Research Funds for Universities[2023RCTD012]Fundamental Research Funds for Universities[2023QNJS075]Inner Mongolia Autonomous Region Postgraduate Research Innovation Project[KC2024053B]Fundamental Research Funds for Universities[2024YXXS012]Open Project of the National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology[GZ2023KF012].
文摘In ultrasonic non-destructive testing of high-temperature industrial equipment,sound velocity drift induced by non-uniform temperature fields can severely compromise defect localization accuracy.Conventional approaches that rely on room-temperature sound velocities introduce systematic errors,potentially leading to misjudgment of safety-critical components.Two primary challenges hinder current methods:first,it is difficult to monitor real-time changes in sound velocity distribution within a thermal gradient;second,traditional uniform-temperature correction models fail to capture the nonlinear dependence of material properties on temperature and their effect on ultrasonic velocity fields.Here,we propose a defect localization correction method based on multiphysics coupling.A two-dimensional coupled heat transfer–wave propagation model is established in COMSOL,and a one-dimensional steady-state heat transfer condition is used to design a numerical pulse–echo experiment in 1020 steel.Temperature-dependent material properties are incorporated,and the intrinsic relationship between sound velocity and temperature is derived,confirming consistency with classical theories.To account for gradient temperature fields,a micro-element integration algorithm discretizes the propagation path into segments,each associated with a locally computed temperature from the steady-state heat conduction solution.Defect positions are dynamically corrected through cumulative displacement along the propagation path.By integrating heat conduction and elastic wave propagation in a multiphysics framework,this method overcomes the limitations of uniform-temperature assumptions.The micro-element integration approach enables dynamic tracking of spatially varying sound velocities,offering a robust strategy to enhance ultrasonic testing accuracy in high-temperature industrial environments.
基金Project supported by the National Natural Science Foundation of China(Grant No.12204128)。
文摘This study investigates the effects of ocean boundaries on modal shapes in very-low-frequency(VLF,1–10 Hz)sound propagation through the deep ocean.Utilizing a normal mode solution formulated in terms of parabolic cylinder functions(PCF),we demonstrate that boundary interactions induce a phase change reduction below-πat frequencies of several hertz.This reduction,in turn,forces a key transition in the solution,shifting the order of the PCF from integer to non-integer values.Analysis of the characteristic shape of the PCF versus its order reveals that these boundary-influenced modes exhibit an energy shift toward deeper regions and a weakened axial convergence of the underwater sound field.
文摘China’s annual Central Economic Work Conference, which ended in Beijing on December 7, emphasized that the country should give priority to the soundness of economic operations instead of the growth rate in the future. Comparing the quality-first approach with the previous focus on GDP growth, a Xinhua News Agency commentary hails the adjustment as a significant change in the development strategy of the country.
基金National Natural Science Foundation of China(No.51705545)。
文摘The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.
文摘Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter.Therefore,the need to monitor disc cutter wear in real-time has emerged as a technical challenge for TBMs.In this study,real-time disc cutter wear monitoring is developed based on sound and vibration sensors.For this purpose,the microphone and accelerometer were used to record the sound and vibration signals of cutting three different types of rocks with varying abrasions on a laboratory scale.The relationship between disc cutter wear and the sound and vibration signal was determined by comparing the measurements of disc cutter wear with the signal plots for each sample.The features extracted from the signals showed that the sound and vibration signals are impacted by the progression of disc wear during the rock-cutting process.The signal features obtained from the rock-cutting operation were utilized to verify the machine learning techniques.The results showed that the multilayer perceptron(MLP),random subspace-based decision tree(RS-DT),DT,and random forest(RF)methods could predict the wear level of the disc cutter with an accuracy of 0.89,0.951,0.951,and 0.927,respectively.Based on the accuracy of the models and the confusion matrix,it was found that the RS-DT model has the best estimate for predicting the level of disc wear.This research has developed a method that can potentially determine when to replace a tool and assess disc wear in real-time.
基金supported by the National Natural Science Foundation of China(No.52271180)the Leading Goose R&D Program of Zhejiang Province(2022C01110).
文摘Metal foams are a fascinating group of materials that possess distinct physicochEMIcal properties and interconnected strut features with high surface area-to-volume ratios, high specific strength and lightweight nature. These characteristics make them ideal for applications in vibration damping, heat insulation and weight reduction. In recent years, there has been increasing interest in the application of interfering energy conversion such as electromagnetic wave (EMW) and sound, where the metal foams could emerge as a solution. This paper will present a comprehensive review of the preparation methods as well as the interference energy converting mechanisms for metal foams. Typically, the progress and prospective aspects of metal foams for EMW absorption, electromagnetic interference (EMI) shielding and sound absorption have been emphasized. Through this review, we aspire to offer valuable insights for the development of multifunctional applications with metal foam materials.
基金funded under the Collaborative Research Initiative Grant Scheme(C-RIGS),grant number C-RIGS24-016-0022 from IIUM.
文摘This review provides a comprehensive overview of natural rubber(NR)composites,focusing on their properties,compounding aspects,and renewable practices involving natural fibre reinforcement.The properties of NR are influenced by the compounding process,which incorporates ingredients such as elastomers,vulcanizing agents,accelerators,activators,and fillers like carbon black and silica.While effective in enhancing properties,these fillers lack biodegradability,prompting the exploration of sustainable alternatives.The potential of natural fibres as renewable reinforcements in NR composites is thoroughly covered in this review,highlighting both their advan-tages,such as improved sustainability,and the challenges they present,such as compatibility with the rubber matrix.Surface treatment methods,including alkali and silane treatments,are also discussed as solutions to improve fibre-matrix adhesion and mitigate these challenges.Additionally,the review highlights the potential of oil palm empty fruit bunch(EFB)fibres as a natural fibre reinforcement.The abundance of EFB fibres and their alignment with sustainable practices make them promising substitutes for conventional fillers,contributing to valuable knowledge and supporting the broader move towards renewable reinforcement to improve sustain-ability without compromising the key properties of rubber composites.
基金supported by the National Key Research and Development Program of China(2022YFA1404400)the National Natural Science Foundation of China(62122072,12174368,61705216,62405306)+4 种基金Anhui Provincial Department of Science and Technology(202203a07020020,18030801138)Anhui Provincial Natural Science Foundation(2308085QA21,2408085QF187)the USTC Research Funds of the Double First-Class Initiative(YD2090002015)the Institute of Artificial Intelligence at Hefei Comprehensive National Science Center(23YGXT005)the Fundamental Research Funds for the Central Universities(WK2090000083).
文摘Ultrasound computed tomography(USCT)is a noninvasive biomedical imaging modality that offers insights into acoustic properties such as the sound speed(SS)and acoustic attenuation(AA)of the human body,enhancing diagnostic accuracy and therapy planning.Full waveform inversion(FWI)is a promising USCT image reconstruction method that optimizes the parameter fields of a wave propagation model via gradient-based optimization.However,twodimensional FWI methods are limited by their inability to account for three-dimensional wave propagation in the elevation direction,resulting in image artifacts.To address this problem,we propose a three-dimensional time-domain full waveform inversion algorithm to reconstruct the SS and AA distributions on the basis of a fractional Laplacian wave equation,adjoint field formulation,and gradient descent optimization.Validated by two sets of simulations,the proposed algorithm has potential for generating high-resolution and quantitative SS and AA distributions.This approach holds promise for clinical USCT applications,assisting early disease detection,precise abnormality localization,and optimized treatment planning,thus contributing to better healthcare outcomes.
基金Beijing Hospitals Authority Clinical Medicine Development of Special Funding Support,Code(Project No.:YGLX202514)。
文摘Objective:To explore the research landscape and hotspots of Computerized Respiratory Sound Analysis(CORSA)and provide a reference for future in-depth studies.Methods:Literature related to CORSA published up to August 27,2020,was retrieved from the Web of Science Core Collection.CiteSpace 5.6.R3 was used to perform co-authorship analysis,institutional collaboration analysis,keyword co-occurrence analysis,and co-citation analysis.Results:A total of 1,897 publications were included.Co-authorship analysis identified several influential contributors,including Zahra Moussavi,Kenneth Sundaraj,and H.Pasterkamp.Major research institutions included the University of Manitoba,the University of Queensland,and Aristotle University of Thessaloniki.Keyword co-occurrence analysis indicated that“respiratory sound,”“lung sound,”“asthma,”“children,”and“classification”were major research themes.The most frequently co-cited articles were published by Arati Gurung(2011),Mohammed Bahoura(2009),and H.Pasterkamp(1997).Highly cited journals included Chest,the American Journal of Respiratory and Critical Care Medicine,and IEEE Transactions on Biomedical Engineering.Conclusion:CORSA research is primarily driven by European and North American scholars and institutions,with China still in an early stage of development.Current hotspots include respiratory sound acquisition and processing,feature extraction methods such as Mel-frequency cepstral coefficients(MFCCs),and classification techniques based on machine learning and deep learning.CORSA is suitable for diverse populations and is widely applied in respiratory diseases,especially bronchial asthma.Its non-invasive nature offers particular advantages for infants and pregnant women.Although CORSA demonstrates strong clinical potential,its clinical translation remains limited.Advancing clinical applications and bridging the gap between research and practice will be key directions for future development.The prominence of top-tier respiratory and engineering journals among citations suggests that CORSA is an emerging and influential research frontier.
