The work presented in this paper aims at investigating the ability of acoustic noise correlation technique for railway infrastructure health monitoring. The principle of this technique is based on impulse responses re...The work presented in this paper aims at investigating the ability of acoustic noise correlation technique for railway infrastructure health monitoring. The principle of this technique is based on impulse responses reconstruction by correlation of random noise propagated in the medium. Since wheel-rail interaction constitutes a source of such noise, correlation technique could be convenient for detection of rail defects using only passive sensors. Experiments have been carried out on a 2 m-long rail sample. Acoustic noise is generated in the sample at several positions. Direct comparison between an active emission-reception response and the estimated noise correlation function has confirmed the validity of the equivalence relation between them. The quality of the reconstruction is shown to be strongly related to the spatial distribution of the noise sources. High sensitivity of the noise-correlation functions to a local defect on the rail is also demonstrated. However, interpretation of the defect signature is more ambiguous than when using classical active responses. Application of a spatiotemporal Fourier transform on data recorded with variable sensor-defect distances has allowed overcoming this ambiguity.展开更多
Passive sampling is a simple and efficacious sampling technique that guarantees a safe collection and transportation of samples to the analysis site, and obtaining results with more temporal resolution. As a case of s...Passive sampling is a simple and efficacious sampling technique that guarantees a safe collection and transportation of samples to the analysis site, and obtaining results with more temporal resolution. As a case of study, passive samplers were deployed in the Ayapel Swamp, Colombia, located in the influence zone of open pit gold mines. Mercury, iron and manganese were sampled at two different depths by the Chemcatcher? passive sampler and regular grab sampling. Additionally, dissolved oxygen, oxidation-reduction potential, pH and water temperature were measured. The results showed that depth and time did not have a significant influence (ANOVA, confidence level of 95%) on mercury concentration on both passive samplers and grab sampling. However, concentration of Fe and Hg in passive samplers had a high positive correlation, but it may be because depth increase during sampling period caused the dilution of both analytes. In conclusion, passive samplers proved to be a valuable tool for understanding the response of mercury to the Ayapel Swamp dynamics.展开更多
Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay,their vocalizations have been rarely investigated.Underwater vocalizations were recorded during March 2017 in Prydz ...Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay,their vocalizations have been rarely investigated.Underwater vocalizations were recorded during March 2017 in Prydz Bay,Antarctica.Bio-duck sounds,downsweeps,inverted“u”shape signals,whistles,pulsed sounds,and broadband clicks were recorded.Bio-duck sounds and downsweeps were associated with Antarctic minke whales(Balaenoptera bonaerensis)based on visual observations.Similarities between inverted“u”shape signals,biphonic calls,and clicks with vocalizations previously described for killer whales(Orcinus orca)lead us believe the presence of Antarctic killer whales.According to sound structures,signal characteristics,and recording location,Antarctic type C killer whales were the most probable candidates to produce these detected calls.These represent the fi rst detection of inverted“u”shape signals in Antarctic waters,and the fi rst report of Antarctic killer whale in Prydz Bay based on passive acoustic monitoring.The co-existence of Antarctic minke and killer whales may imply that minke whales can detect diff erences between the sounds of mammal-eating and fi sh-eating killer whales.Our descriptions of these underwater vocalizations contribute to the limited body of information regarding the distribution and acoustic behavior of cetaceans in Prydz Bay.展开更多
BACKGROUND:In the management of critically ill patients,the assessment of volume responsiveness and the decision to administer a fluid bolus constitute a common dilemma for physicians.Static indices of cardiac preload...BACKGROUND:In the management of critically ill patients,the assessment of volume responsiveness and the decision to administer a fluid bolus constitute a common dilemma for physicians.Static indices of cardiac preload are poor predictors of volume responsiveness.Passive leg raising(PLR) mimics an endogenous volume expansion(VE) that can be used to predict fluid responsiveness.This study was to assess the changes in stroke volume index(SVI) induced by PLR as an indicator of fluid responsiveness in mechanically ventilated patients with severe sepsis.METHODS:This was a prospective study.Thirty-two mechanically ventilated patients with severe sepsis were admitted for VE in ICU of the First Affiliated Hospital,Zhejiang University School of Medicine and Ningbo Medical Treatment Center Lihuili Hospital from May 2010 to December 2011.Patients with non-sinus rhythm or arrhythmia,parturients,and amputation of the lower limbs were excluded.Measurements of SVI were obtained in a semi-recumbent position(baseline) and during PLR by the technique of pulse indicator continuous cardiac output(PiCCO) system prior to VE.Measurements were repeated after VE(500 mL 6%hydroxyethyl starch infusion within 30 minutes)to classify patients as either volume responders or non-responders based on their changes in stroke volume index(ASVI) over 15%.Heart rate(HR),systolic artery blood pressure(ABPs),diastolic artery blood pressure(ABPd),mean arterial blood pressure(ABPm),mean central venous pressure(CVPm)and cardiac index(CI) were compared between the two groups.The changes of ABPs,ABPm,CVPm,and SVI after PLR and VE were compared with the indices at the baseline.The ROC curve was drawn to evaluate the value of ASVI and the change of CVPm(ACVPm) in predicting volume responsiveness.SPSS 17.0 software was used for statistical analysis.RESULTS:Among the 32 patients,22 were responders and 10 were non-responders.After PLR among the responders,some hemodynamic variables(including ABPs,ABPd,ABPm and CVPm)were significantly elevated(101.2±17.6 vs.118.6±23.7,P=0.03;52.8±10.7 vs.64.8±10.7,P=0.006;68.3+11.7 vs.81.9±14.4,P=0.008;6.8±3.2 vs.11.9±4.0,P=0.001).After PLR,the area under curve(AUC) and the ROC curve of △SV1 and ACVPm for predicting the responsiveness after VE were0.882±0.061(95%CI 0.759-1.000) and 0.805±0.079(95%CI 0.650-0.959) when the cut-off levels of ASVI and ACVPm were 8.8%and 12.7%,the sensitivities were 72.7%and 72.7%,and the specificities were 80%and 80%.CONCLUSION:Changes in ASVI and ACVPm induced by PLR are accurate indices for predicting fluid responsiveness in mechanically ventilated patients with severe sepsis.展开更多
Epidermal electronics with superb passive-cooling capabilities are of great value for both daytime outdoor dressing comfort and low-carbon economy. Herein, a multifunctional and skinattachable electronic is rationally...Epidermal electronics with superb passive-cooling capabilities are of great value for both daytime outdoor dressing comfort and low-carbon economy. Herein, a multifunctional and skinattachable electronic is rationally developed on a porous all-elastomer metafabric for efficient passive daytime radiative cooling(PDRC) and human electrophysiological monitoring. The cooling characteristics are realized through the homogeneous impregnation of polytetrafluoroethylene microparticles in the styrene–ethylene–butylene–styrene fibers, and the rational regulation of microporosity in SEBS/PTFE metafabrics, thus synergistically backscatter ultraviolet–visible–near-infrared light(maximum reflectance over 98.0%) to minimize heat absorption while efficiently emit human-body midinfrared radiation to the sky. As a result, the developed PDRC metafabric achieves approximately 17℃ cooling effects in an outdoor daytime environment and completely retains its passive cooling performance even under 50% stretching. Further, high-fidelity electrophysiological monitoring capability is also implemented in the breathable and skin-conformal metafabric through liquid metal printing, enabling the accurate acquisition of human electrocardiograph, surface electromyogram, and electroencephalograph signals for comfortable and lengthy health regulation. Hence, the fabricated superelastic PDRC metafabric opens a new avenue for the development of body-comfortable electronics and low-carbon wearing technologies.展开更多
Piezoelectric material,as one of the great potential materials,had attracted lots of attention all over the world due to its distinguish advantages.In this paper,the development of piezoelectric-based technology for a...Piezoelectric material,as one of the great potential materials,had attracted lots of attention all over the world due to its distinguish advantages.In this paper,the development of piezoelectric-based technology for application in the field of civil structural health monitoring(CSHM),was summarized and discussed.Based on the different identification mechanisms,the piezoelectric transducer-based technology can be divided into two main approaches as the active or passive sensing and detection methods.This paper summarized the development of these two approaches and discussed their applications in the area of civil structural health monitoring,such as structural and concrete engineering,bridge engineering,pipeline engineering,protection engineering for geological hazards and earthquake disasters,and so on.In addition,the electrical mechanical impedance(EMI)technique,as one of the active identification methods,was also detailly presented.Finally,its great potential for the piezoelectric-based technique was presented based on the detail discussion,especially in the areas of civil structural health monitoring.展开更多
Passive seismic techniques have revolutionarised seismology, leading for example to increased resolution in surface wave tomography, to the possibility to monitor changes in the propagation medium, and to many new pro...Passive seismic techniques have revolutionarised seismology, leading for example to increased resolution in surface wave tomography, to the possibility to monitor changes in the propagation medium, and to many new processing strategies in seismic exploration. Here we review applications of the new techniques to a very particular dataset, namely data from the Apollo 17 lunar network. The special conditions of the lunar noise environment are investigated, illustrating the interplay between the properties of the noise and the ability to reconstruct Green＇s functions. With a dispersion analysis of reconstructed Rayleigh waves new information about the shallow shear velocity structure of the Moon are obtained. Passive image interferometry is used to study the effect of temperature changes in the subsurface on the seismic velocities providing direct observation of a dynamic process in the lunar environment. These applications highlight the potential of passive techniques for terrestrial and planetary seismology.展开更多
文摘The work presented in this paper aims at investigating the ability of acoustic noise correlation technique for railway infrastructure health monitoring. The principle of this technique is based on impulse responses reconstruction by correlation of random noise propagated in the medium. Since wheel-rail interaction constitutes a source of such noise, correlation technique could be convenient for detection of rail defects using only passive sensors. Experiments have been carried out on a 2 m-long rail sample. Acoustic noise is generated in the sample at several positions. Direct comparison between an active emission-reception response and the estimated noise correlation function has confirmed the validity of the equivalence relation between them. The quality of the reconstruction is shown to be strongly related to the spatial distribution of the noise sources. High sensitivity of the noise-correlation functions to a local defect on the rail is also demonstrated. However, interpretation of the defect signature is more ambiguous than when using classical active responses. Application of a spatiotemporal Fourier transform on data recorded with variable sensor-defect distances has allowed overcoming this ambiguity.
文摘Passive sampling is a simple and efficacious sampling technique that guarantees a safe collection and transportation of samples to the analysis site, and obtaining results with more temporal resolution. As a case of study, passive samplers were deployed in the Ayapel Swamp, Colombia, located in the influence zone of open pit gold mines. Mercury, iron and manganese were sampled at two different depths by the Chemcatcher? passive sampler and regular grab sampling. Additionally, dissolved oxygen, oxidation-reduction potential, pH and water temperature were measured. The results showed that depth and time did not have a significant influence (ANOVA, confidence level of 95%) on mercury concentration on both passive samplers and grab sampling. However, concentration of Fe and Hg in passive samplers had a high positive correlation, but it may be because depth increase during sampling period caused the dilution of both analytes. In conclusion, passive samplers proved to be a valuable tool for understanding the response of mercury to the Ayapel Swamp dynamics.
基金Supported by the National Natural Science Foundation of China(No.41906170)the Indian Ocean Ninety-east Ridge Ecosystem and Marine Environment Monitoring and Protection(No.DY135-E2-4)+1 种基金the Cooperation of Top Predators Observation in the Southern Ocean(No.QT4519003)the China-ASEAN Maritime Cooperation Fund。
文摘Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay,their vocalizations have been rarely investigated.Underwater vocalizations were recorded during March 2017 in Prydz Bay,Antarctica.Bio-duck sounds,downsweeps,inverted“u”shape signals,whistles,pulsed sounds,and broadband clicks were recorded.Bio-duck sounds and downsweeps were associated with Antarctic minke whales(Balaenoptera bonaerensis)based on visual observations.Similarities between inverted“u”shape signals,biphonic calls,and clicks with vocalizations previously described for killer whales(Orcinus orca)lead us believe the presence of Antarctic killer whales.According to sound structures,signal characteristics,and recording location,Antarctic type C killer whales were the most probable candidates to produce these detected calls.These represent the fi rst detection of inverted“u”shape signals in Antarctic waters,and the fi rst report of Antarctic killer whale in Prydz Bay based on passive acoustic monitoring.The co-existence of Antarctic minke and killer whales may imply that minke whales can detect diff erences between the sounds of mammal-eating and fi sh-eating killer whales.Our descriptions of these underwater vocalizations contribute to the limited body of information regarding the distribution and acoustic behavior of cetaceans in Prydz Bay.
文摘BACKGROUND:In the management of critically ill patients,the assessment of volume responsiveness and the decision to administer a fluid bolus constitute a common dilemma for physicians.Static indices of cardiac preload are poor predictors of volume responsiveness.Passive leg raising(PLR) mimics an endogenous volume expansion(VE) that can be used to predict fluid responsiveness.This study was to assess the changes in stroke volume index(SVI) induced by PLR as an indicator of fluid responsiveness in mechanically ventilated patients with severe sepsis.METHODS:This was a prospective study.Thirty-two mechanically ventilated patients with severe sepsis were admitted for VE in ICU of the First Affiliated Hospital,Zhejiang University School of Medicine and Ningbo Medical Treatment Center Lihuili Hospital from May 2010 to December 2011.Patients with non-sinus rhythm or arrhythmia,parturients,and amputation of the lower limbs were excluded.Measurements of SVI were obtained in a semi-recumbent position(baseline) and during PLR by the technique of pulse indicator continuous cardiac output(PiCCO) system prior to VE.Measurements were repeated after VE(500 mL 6%hydroxyethyl starch infusion within 30 minutes)to classify patients as either volume responders or non-responders based on their changes in stroke volume index(ASVI) over 15%.Heart rate(HR),systolic artery blood pressure(ABPs),diastolic artery blood pressure(ABPd),mean arterial blood pressure(ABPm),mean central venous pressure(CVPm)and cardiac index(CI) were compared between the two groups.The changes of ABPs,ABPm,CVPm,and SVI after PLR and VE were compared with the indices at the baseline.The ROC curve was drawn to evaluate the value of ASVI and the change of CVPm(ACVPm) in predicting volume responsiveness.SPSS 17.0 software was used for statistical analysis.RESULTS:Among the 32 patients,22 were responders and 10 were non-responders.After PLR among the responders,some hemodynamic variables(including ABPs,ABPd,ABPm and CVPm)were significantly elevated(101.2±17.6 vs.118.6±23.7,P=0.03;52.8±10.7 vs.64.8±10.7,P=0.006;68.3+11.7 vs.81.9±14.4,P=0.008;6.8±3.2 vs.11.9±4.0,P=0.001).After PLR,the area under curve(AUC) and the ROC curve of △SV1 and ACVPm for predicting the responsiveness after VE were0.882±0.061(95%CI 0.759-1.000) and 0.805±0.079(95%CI 0.650-0.959) when the cut-off levels of ASVI and ACVPm were 8.8%and 12.7%,the sensitivities were 72.7%and 72.7%,and the specificities were 80%and 80%.CONCLUSION:Changes in ASVI and ACVPm induced by PLR are accurate indices for predicting fluid responsiveness in mechanically ventilated patients with severe sepsis.
基金financially supported by the National Natural Science Foundation of China (21875033, 52161135302)the Research Foundation Flanders (G0F2322N)+4 种基金the China Postdoctoral Science Foundation (2022M711355)the Natural Science Foundation of Jiangsu Province (BK20221540)the Shanghai Scientific and Technological Innovation Project (18JC1410600)the Program of the Shanghai Academic Research Leader (17XD1400100)the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX22_2317)。
文摘Epidermal electronics with superb passive-cooling capabilities are of great value for both daytime outdoor dressing comfort and low-carbon economy. Herein, a multifunctional and skinattachable electronic is rationally developed on a porous all-elastomer metafabric for efficient passive daytime radiative cooling(PDRC) and human electrophysiological monitoring. The cooling characteristics are realized through the homogeneous impregnation of polytetrafluoroethylene microparticles in the styrene–ethylene–butylene–styrene fibers, and the rational regulation of microporosity in SEBS/PTFE metafabrics, thus synergistically backscatter ultraviolet–visible–near-infrared light(maximum reflectance over 98.0%) to minimize heat absorption while efficiently emit human-body midinfrared radiation to the sky. As a result, the developed PDRC metafabric achieves approximately 17℃ cooling effects in an outdoor daytime environment and completely retains its passive cooling performance even under 50% stretching. Further, high-fidelity electrophysiological monitoring capability is also implemented in the breathable and skin-conformal metafabric through liquid metal printing, enabling the accurate acquisition of human electrocardiograph, surface electromyogram, and electroencephalograph signals for comfortable and lengthy health regulation. Hence, the fabricated superelastic PDRC metafabric opens a new avenue for the development of body-comfortable electronics and low-carbon wearing technologies.
基金the National Natural Science Funding of China(No.51878628,51708520).
文摘Piezoelectric material,as one of the great potential materials,had attracted lots of attention all over the world due to its distinguish advantages.In this paper,the development of piezoelectric-based technology for application in the field of civil structural health monitoring(CSHM),was summarized and discussed.Based on the different identification mechanisms,the piezoelectric transducer-based technology can be divided into two main approaches as the active or passive sensing and detection methods.This paper summarized the development of these two approaches and discussed their applications in the area of civil structural health monitoring,such as structural and concrete engineering,bridge engineering,pipeline engineering,protection engineering for geological hazards and earthquake disasters,and so on.In addition,the electrical mechanical impedance(EMI)technique,as one of the active identification methods,was also detailly presented.Finally,its great potential for the piezoelectric-based technique was presented based on the detail discussion,especially in the areas of civil structural health monitoring.
文摘Passive seismic techniques have revolutionarised seismology, leading for example to increased resolution in surface wave tomography, to the possibility to monitor changes in the propagation medium, and to many new processing strategies in seismic exploration. Here we review applications of the new techniques to a very particular dataset, namely data from the Apollo 17 lunar network. The special conditions of the lunar noise environment are investigated, illustrating the interplay between the properties of the noise and the ability to reconstruct Green＇s functions. With a dispersion analysis of reconstructed Rayleigh waves new information about the shallow shear velocity structure of the Moon are obtained. Passive image interferometry is used to study the effect of temperature changes in the subsurface on the seismic velocities providing direct observation of a dynamic process in the lunar environment. These applications highlight the potential of passive techniques for terrestrial and planetary seismology.
基金supported by the National Natural Science Foundation of China(42304056)the Joint Open Fund of Mengcheng National Geophysical Observatory(MENGO-202103)the Fundamental Research Funds for the Central Universities(WK2080000153).
