A scheme to improve the quality in ghost imaging(GI)by controlling the bandwidth of light source(BCGI)is proposed.The theoretical and numerical results show that the reconstruction result with high quality can be obta...A scheme to improve the quality in ghost imaging(GI)by controlling the bandwidth of light source(BCGI)is proposed.The theoretical and numerical results show that the reconstruction result with high quality can be obtained by adjusting the bandwidth range of the light source appropriately,and the selection criterion of the bandwidth is analyzed by the power distribution of the imaging target.A proof-of-principle experiment is implemented to verify the theoretical and numerical results.In addition,the BCGI also presents better anti-noise performance when compared with some popular GI methods.展开更多
A new method for recharging active medical implant(AMI)in vitro based on incoherent light source and results of the simulation experiments are proposed.Firstly,the models of the AMI recharging method based on incohere...A new method for recharging active medical implant(AMI)in vitro based on incoherent light source and results of the simulation experiments are proposed.Firstly,the models of the AMI recharging method based on incoherent light source in vitro are developed,which include the models of an incoherent light source and skin tissue.Secondly,simulation experiments of the incoherent light source of the AMI recharging process in vitro based on the Monte Carlo(MC)method are carried out.Finally,absorbed fractions of different layers and distributions of density along x axis of the tissue model and other important conclusions have been achieved.展开更多
Continuous deforming always leads to the performance degradation of a flexible triboelectric nanogenerator due to the Young’s modulus mismatch of different functional layers.In this work,we fabricated a fiber-shaped ...Continuous deforming always leads to the performance degradation of a flexible triboelectric nanogenerator due to the Young’s modulus mismatch of different functional layers.In this work,we fabricated a fiber-shaped stretchable and tailorable triboelectric nanogenerator(FST-TENG)based on the geometric construction of a steel wire as electrode and ingenious selection of silicone rubber as triboelectric layer.Owing to the great robustness and continuous conductivity,the FST-TENGs demonstrate high stability,stretchability,and even tailorability.For a single device with ~6 cm in length and ~3 mm in diameter,the open-circuit voltage of ~59.7 V,transferred charge of ~23.7 nC,short-circuit current of ~2.67 μA and average power of ~2.13 μW can be obtained at 2.5 Hz.By knitting several FST-TENGs to be a fabric or a bracelet,it enables to harvest human motion energy and then to drive a wearable electronic device.Finally,it can also be woven on dorsum of glove to monitor the movements of gesture,which can recognize every single finger,different bending angle,and numbers of bent finger by analyzing voltage signals.展开更多
BACKGROUND Conventionally, the low luminous intensity, low image resolution, and difficulty in operation have been reported with the ultrathin endoscope. However, it has markedly advanced recently. The improvement of ...BACKGROUND Conventionally, the low luminous intensity, low image resolution, and difficulty in operation have been reported with the ultrathin endoscope. However, it has markedly advanced recently. The improvement of the diagnostic ability is expected.AIM To compare the early gastric cancer diagnostic ability of an ultrathin endoscope loaded with a laser light source and that of the conventional endoscope.METHODS The target subjects were 375 consecutive patients who underwent endoscopy at our hospital for post-endoscopic submucosal dissection follow-up of gastric cancer from January to August 2018. During endoscopy, the ultrathin endoscope was used in 140 patients(37.3%), and the conventional endoscope was used in235 patients(62.7%). Patient background was adjusted using the propensity score matching method, and gastric cancer detection ability was evaluated in the two groups.RESULTS The gastric cancer detection rate was 7.8% in the ultrathin endoscope group and7.0% in the conventional endoscope group, and the mean intragastric observation time was 4.1 ± 1.7 min in the ultrathin endoscope group and 4.1 ± 1.9 min in the conventional endoscope group, showing no significant differences between the groups. Moreover, the biopsy implementation rate was 31.8% in the ultrathin endoscope group and 41.1% in the conventional endoscope group, and the biopsy prediction rate was 17.9% and 13.2%, respectively, showing no significant differences between the groups.CONCLUSION The gastric cancer diagnostic ability of the ultrathin endoscope loaded with a laser light source was comparable to that of the conventional endoscope. The observation time was also comparable. Thus, endoscopy using the ultrathin endoscope loaded with the laser light source would be the first option in screening examinations of gastric cancer due to its low invasion.展开更多
Active seismic sources are critical for obtaining high resolution images of the subsurface.For active imaging in urban areas,environment friendly and green seismic sources are required.In present work,we introduce a n...Active seismic sources are critical for obtaining high resolution images of the subsurface.For active imaging in urban areas,environment friendly and green seismic sources are required.In present work,we introduce a new type of green active source based on the gaseous detonation of methane and oxygen.When fired in a closed container,the chemical reaction,i.e.gaseous detonation,will produce high pressure air over 150 MPa.Seismic waves are produced when high pressure air is quickly released to impact the surroundings.The first field experiment of this active source was carried out in December,2017 in Jingdezhen,Jiangxi Province,where a series of active sources were excited to explore their potential in mine exploration.In current work,we analyzed the seismic waves recorded by near-field accelerators and a dense short-period seismic array and compared them with those from a mobile airgun source,another kind of active source by releasing high pressure air into water.The results demonstrate that it can be used for high resolution near surface imaging.Firstly,the gaseous detonation productions are harmless CO2 and water,making it a green explosive source.Secondly,the dominant seismic frequencies are 10-80 Hz and a single shot can be recorded up to 15 km,making it suitable for local structure investigations.Thirdly,it can be excited in vertical wells,similar to traditional powder explosive sources.It can also act as an additional on-land active source to airgun sources,which requires a suitable water body as intermediate media to generate repeating signals.Moreover,the short duration and high frequency signature of the source signals make it safe with no damage to nearby buildings.These make it convenient to excite in urban areas.As a new explosive source,the excitation equipment and conditions,such as gas ratio,sink depth and air-releasing directions,need further investigation to improve seismic wave generation efficiency.展开更多
A method based on multiple images captured under different light sources at different incident angles was developed to recognize the coal density range in this study.The innovation is that two new images were construc...A method based on multiple images captured under different light sources at different incident angles was developed to recognize the coal density range in this study.The innovation is that two new images were constructed based on images captured under four single light sources.Reconstruction image 1 was constructed by fusing greyscale versions of the original images into one image,and Reconstruction image2 was constructed based on the differences between the images captured under the different light sources.Subsequently,the four original images and two reconstructed images were input into the convolutional neural network AlexNet to recognize the density range in three cases:-1.5(clean coal) and+1.5 g/cm^(3)(non-clean coal);-1.8(non-gangue) and+1.8 g/cm^(3)(gangue);-1.5(clean coal),1.5-1.8(middlings),and+1.8 g/cm^(3)(gangue).The results show the following:(1) The reconstructed images,especially Reconstruction image 2,can effectively improve the recognition accuracy for the coal density range compared with images captured under single light source.(2) The recognition accuracies for gangue and non-gangue,clean coal and non-clean coal,and clean coal,middlings,and gangue reached88.44%,86.72% and 77.08%,respectively.(3) The recognition accuracy increases as the density moves further away from the boundary density.展开更多
In seismic data processing,picking of the P-wave first arrivals takes up plenty of time and labor,and its accuracy plays a key role in imaging seismic structures.Based on the convolution neural network(CNN),we propose...In seismic data processing,picking of the P-wave first arrivals takes up plenty of time and labor,and its accuracy plays a key role in imaging seismic structures.Based on the convolution neural network(CNN),we propose a new method to pick up the P-wave first arrivals automatically.Emitted from MINI28 vibroseis in the Jingdezhen seismic experiment,the vertical component of seismic waveforms recorded by EPS 32-bit portable seismometers are used for manually picking up the first arrivals(a total of 7242).Based on these arrivals,we establish the training and testing sets,including 25,290 event samples and 710,616 noise samples(length of each sample:2 s).After 3,000 steps of training,we obtain a convergent CNN model,which can automatically classify seismic events and noise samples with high accuracy(>99%).With the trained CNN model,we scan continuous seismic records and take the maximum output(probability of a seismic event)as the P-wave first arrival time.Compared with STA/LTA(short time average/long time average),our method shows higher precision and stronger anti-noise ability,especially with the low SNR seismic data.This CNN method is of great significance for promoting the intellectualization of seismic data processing,improving the resolution of seismic imaging,and promoting the joint inversion of active and passive sources.展开更多
The exciting source of the active source repeated monitoring is located in the Xiliushui Reservoir in Zhangye,Gansu Province. The system began operating normally on July 9,2015,and we had completed a period of 40 days...The exciting source of the active source repeated monitoring is located in the Xiliushui Reservoir in Zhangye,Gansu Province. The system began operating normally on July 9,2015,and we had completed a period of 40 days of continuous excitation experiment before November 10,2015. Our results reveal that the airgun source has good consistency and repeatability,and the detective system of active source can record signal clearly. The construction of active source repeated exploration projects has achieved some results,which can provide valuable experience for the research of active source repeated exploration. The observation data we obtained makes it possible to follow the temporal and spatial variations of the deep structure of the Qilian Mountain areas.展开更多
The Anninghe fault is a large left-lateral strike-slip fault in southwestern China. It has controlled deposition and magmatic activities since the Proterozoic, and seismic activity occurs frequently. The Mianning-Xich...The Anninghe fault is a large left-lateral strike-slip fault in southwestern China. It has controlled deposition and magmatic activities since the Proterozoic, and seismic activity occurs frequently. The Mianning-Xichang segment of the Anninghe fault is a seismic gap that has been locked by high stress. Many studies suggest that this segment has great potential for large earthquakes(magnitude >7). We obtained three vertical velocity profiles of the Anninghe fault(between Mianning and Xichang) based on the inversion of P-wave first arrival times. The travel time data were picked from seismograms generated by methane gaseous sources and recorded by three linearly distributed across-fault dense arrays. The inversion results show that the P-wave velocity structures at depths of 0-2 km corresponds well with the local lithology. The Quaternary sediments have low seismic velocities, whereas the igneous rocks,metamorphic rocks, and bedrock have high seismic velocities. We then further discuss the fault activities of the two fault branches of the Anninghe fault in the study region based on small earthquakes(magnitudes between ML 0.5 and ML 2.5) detected by the Xichang array.The eastern fault branch is more active than the western branch and that the fault activities in the eastern branch are different in the northern and southern segments at the border of 28°21′N. The high-resolution models obtained are essential for future earthquake rupture simulations and hazard assessments of the Anninghe fault zone. Future studies of velocity models at greater depths may further explain the complex fault activities in the study region.展开更多
The seismic waveforms may present subtle changes related to the external loadings such as earthquakes(Pei Shunping et al.,2019)and landslides(Larose E.et al.,2015).Monitoring subtle changes provides a complementary to...The seismic waveforms may present subtle changes related to the external loadings such as earthquakes(Pei Shunping et al.,2019)and landslides(Larose E.et al.,2015).Monitoring subtle changes provides a complementary tool for studying the dynamic processes(e.g.,Niu Fenglin et al.,2008),which has long been a major subject in seismology.The subsurface can be monitored by using natural repetitive events including repeated earthquakes(e.g.,Song Xiaodong et al.,1996)and ambient seismic noises(e.g.,Mao Shujuan et al.,2019).展开更多
We tested 288 pieces of the polished cabochon jadeite-jade with high quality green and smooth surfaces using the colorimeter Color i5 based on the CIE 1976 L~*a~*b~* uniform color space. The color changes after altern...We tested 288 pieces of the polished cabochon jadeite-jade with high quality green and smooth surfaces using the colorimeter Color i5 based on the CIE 1976 L~*a~*b~* uniform color space. The color changes after alternating three CIE standard light sources D_(65),A and CWF were compared,and the degree of metamerism was evaluated. The results show that the CIE standard light sources D_(65),A and CWF increase the chroma of green and turn bluish green into vivid green,which are similar or to nearly colorless and transparent glass-like samples with fine textures. When the three light sources were individually alternated,the lightness of the jadeite-jades showed little change,but the tone changed significantly. Metamerism occurred only in 3 pairs among the 16 samples that were selected by cluster analysis for quality,and the metamerism colors were highly consistent of L~*D_(65)∈(43.47,46.75),C~*D_(65)∈(65.20,68.80) and ho~*D_(65)∈(138.10,140.23). We can conclude that the jadeite-jade green gradually turns to blue when the color temperature of the light source increases. But when considering both the light sources and the samples,D_(65) is more suitable to be the light source of jadeite-jade green when compared with the light sources CWF and A. Compared with the CIE standard green and high chroma green,high-quality jadeite-jade green has a slight yellow tone,low lightness and high chroma. The special metamerism index decreased to 1 when the light source alternated among D_(65),A and CWF. Therefore,the color of jadeite-jade green might be slightly influenced by alternating of the light sources.展开更多
With the epidemic of the coronavirus disease(COVID-19) infection, AlGaN-based ultraviolet-C light emitting diodes(UVC-LEDs) have attracted widespread attention for their sterilization application. However, the sterili...With the epidemic of the coronavirus disease(COVID-19) infection, AlGaN-based ultraviolet-C light emitting diodes(UVC-LEDs) have attracted widespread attention for their sterilization application. However, the sterilization characters of high power integrated light sources(ILSs) haven’t been widely investigated before utilizing in public sanitary security. In this work,by integrating up to 195 UVC-LED chips, high power UVC-LED ILSs with a light output power(LOP) of 1.88 W were demonstrated. The UVC-LED ILSs were verified to have efficient and rapid sterilization capability, which have achieved more than99.9% inactivation rate of several common pathogenic microorganisms within 1 s. In addition, the corresponding air sterilization module based on them was also demonstrated to kill more than 97% of Staphylococcus albus in the air of 20 m3 confined room within 30 min. This work demonstrates excellent sterilization ability of UVC-LED ILSs with high LOP, revealing great potential of UVC-LEDs in sterilization applications in the future.展开更多
In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body,two active source seismic profles were arranged near a small to...In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body,two active source seismic profles were arranged near a small town named Tamusu,Western China.The study area is with complex surface conditions,thus the seismic exploration encountered a variettraveltimey of technical difculties such as crossing obstacles,de-noising harmful scattered waves,and building complex near-surface velocity models.In order to address those problems,techniques including cross-obstacle seismic geometry design,angle-domain harmful scattered noise removal,and an acoustic wave equation-based inversion method jointly utilizing both the and waveform of frst arrival waves were adopted.The fnal seismic images clearly exhibit the target rock’s unconformable contact boundary and its top interface beneath the sedimentary and weathered layers.On this basis,it could be confrmed that the target rock is not thin or has been transported by geological process from somewhere else,but a native and massive rock.There are a few small size fractures whose space distribution could be revealed by seismic images within the rock.The fractures should be kept away.Based on current research,it could be considered that active source seismic exploration is demanded during the sitting process of the geological disposal repository for nuclear waste.The seismic acquisition and processing techniques proposed in the present paper would ofer a good reference value for similar researches in the future.展开更多
A visible-light photocatalyst was prepared by calcination of the hydrolysis product of Ti（SO4）2 with ammonia as precipitator. The color of this photocatalyst was vivid yellow. It could absorb light under 550 nm wave...A visible-light photocatalyst was prepared by calcination of the hydrolysis product of Ti（SO4）2 with ammonia as precipitator. The color of this photocatalyst was vivid yellow. It could absorb light under 550 nm wavelength. The crystal structure of anatase was characterized by XRD. The structure analysis result of X-ray fluorescence（XRF） shows that doped-nitrogen was presented in the sample. The photocatalytic activities were evaluated using methyl orange and phenol as model pollutants. The photocatalytic activities of samples were increasing gradually with calcination temperature from 400℃ to 700℃ under UV irradiation. It can be seen that the degradation of methyl orange follows zero-order kinetics. However, the calcination temperatures have no significant influence on the degradation of phenol under sunlight. The N-doped catalyst shows higher activity than the bare one under solar irradiation.展开更多
Analyzing the information carriede by seismic waves is a major means for human beings to have an insight into the structure of the earth’s interior,and by using artificial seismic sources to excite seismic waves,we c...Analyzing the information carriede by seismic waves is a major means for human beings to have an insight into the structure of the earth’s interior,and by using artificial seismic sources to excite seismic waves,we can obtain high-resolution images for the crustal and smaller scale medium.Artificial seismic exploration methods have been widely applied to fields such as展开更多
The Tibetan plateau as one of the youngest orogen on the Earth was considered as the result of continent-continent collision between the Eurasian and Indian plates.The thickness and structure of the crust beneath Tibe...The Tibetan plateau as one of the youngest orogen on the Earth was considered as the result of continent-continent collision between the Eurasian and Indian plates.The thickness and structure of the crust beneath Tibetan plateau is essential to understand deformation behavior of the plateau.Active-source seismic profiling is most available geo-physical method for imaging the structure of the continental crust.The results from more than 25 active-sources seismic profiles carried out in the past twenty years were reviewed in this article.A preliminary cross crustal pattern of the Tibetan Pla-teau was presented and discussed.The Moho discontinuity buries at the range of 60-80 km on average and have steep ramps located roughly beneath the sutures that are compatible with the successive stacking/accretion of the former Cenozoic blocks northeastward.The deepest Moho(near 80 km) appears closely near IYS and the crustal scale thrust system beneath southern margin of Tibetan plateau suggests strong dependence on collision and non-distributed deformation there.However,the ～20 km order of Moho offsets hardly reappears in the inline section across northern Tibetan plateau.Without a universally accepted,convincing dynamic explanation model accommodated the all of the facts seen in controlled seismic sections,but vertical thickening and northeastern shorten of the crust is quite evident and interpretable to a certain extent as the result of continent-continent collision.Simultaneously,weak geophysical signature of the BNS suggests that convergence has been accommodated perhaps partially through pure-shear thickening accompanied by removal of lower crustal material by lateral escape.Recent years the result of Moho with ～7 km offset and long extend in south-dip angle beneath the east Kunlun oro-gen and a grand thrust fault at the northern margin of Qilian orogen has attract more attention to action from the northern blocks.The broad lower-velocity area in the upper-middle crust of the Lhasa block was once considered as resulted from partially melted rocks.However the low normal vP/vS ratio and the Moho stepwise rise fail to support significant partial melting in the middle-lower crust of the central-northern Tibetan plateau.Furthermore,the lower-velocity of crust occasionally disappears,and/or local thinned exhibits their non-stationary spatial distribution.展开更多
The different reflection characteristics of the surface of tin steel strips and the different speeds of the tinning line demand an adaptive illumination light source for online machine vision inspection.This light sou...The different reflection characteristics of the surface of tin steel strips and the different speeds of the tinning line demand an adaptive illumination light source for online machine vision inspection.This light source can be integrated with a time delay integration charge-coupled device(TDI CCD)to capture the images of moving objects and facilitate inspection of the surface quality of tin steel strips.On-site application show the effectiveness of the TDI camera with the adaptive illumination light source in detecting the surface defects on tin steel strips of three different materials and with different tin coating weights.展开更多
We continuously monitor the long-term seismic velocity variation of one of the major ruptured faults of the devastating 2008 Mw7.9 Wenchuan earthquake in China from July 2009 to January 2012,jointly using accurately c...We continuously monitor the long-term seismic velocity variation of one of the major ruptured faults of the devastating 2008 Mw7.9 Wenchuan earthquake in China from July 2009 to January 2012,jointly using accurately controlled routinely operated signal system active source and seismic noise-based monitoring technique.Our measurements show that the temporal velocity change is not homogeneous and highly localized in the damaged fault zone and the adjacent areas.Velocity variations from the active and passive methods are quite consistent,which both are characterized by ±0.2 % seasonal variation,with peak and trough at winter and summer,respectively.The periodic velocity variation within fault zone exhibits remarkably positive correlation with barometric pressure with stress sensitivity in the order of 10-6Pa-1,suggesting that the plausible mechanism might be the crack density variation of the shallow subsurface medium of the damaged fault zone in response to the cyclic barometric pressure loading.展开更多
A brief introduction of semiconductor self-assembled quantum dots (QDs) applied in single-photon sources is given. Single QDs in confined quantum optical microcavity systems are reviewed along with their optical prope...A brief introduction of semiconductor self-assembled quantum dots (QDs) applied in single-photon sources is given. Single QDs in confined quantum optical microcavity systems are reviewed along with their optical properties and coupling characteristics. Subsequently, the recent progresses in In(Ga)As QDs systems are summarized including the preparation of quantum light sources, multiple methods for embedding single QDs into different microcavities and the scalability of single-photon emitting wavelength. Particularly, several In(Ga)As QD single-photon devices are surveyed including In(Ga)As QDs coupling with nanowires, InAs QDs coupling with distributed Bragg reflection microcavity and the In(Ga)As QDs coupling with micropillar microcavities. Furthermore, applications in the field of single QDs technology are illustrated, such as the entangled photon emission by spontaneous parametric down conversion, the single-photon quantum storage, the chip preparation of single-photon sources as well as the single-photon resonance-fluorescence measurements.展开更多
A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequenc...A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequency con-verter is obtained with low switching frequency converter. It is very promising in current-source APF that adopt super-conducting magnetic energy storage component.展开更多
基金the National Natural Science Foundation of China(Grant Nos.61871431,61971184,and 62001162).
文摘A scheme to improve the quality in ghost imaging(GI)by controlling the bandwidth of light source(BCGI)is proposed.The theoretical and numerical results show that the reconstruction result with high quality can be obtained by adjusting the bandwidth range of the light source appropriately,and the selection criterion of the bandwidth is analyzed by the power distribution of the imaging target.A proof-of-principle experiment is implemented to verify the theoretical and numerical results.In addition,the BCGI also presents better anti-noise performance when compared with some popular GI methods.
基金Supported by the Excellent Young Scholars Research Fund of Beijing Institute of Technology(3040012211310)the Basic Research Fund of Beijing Institute of Technology(20120442010)
文摘A new method for recharging active medical implant(AMI)in vitro based on incoherent light source and results of the simulation experiments are proposed.Firstly,the models of the AMI recharging method based on incoherent light source in vitro are developed,which include the models of an incoherent light source and skin tissue.Secondly,simulation experiments of the incoherent light source of the AMI recharging process in vitro based on the Monte Carlo(MC)method are carried out.Finally,absorbed fractions of different layers and distributions of density along x axis of the tissue model and other important conclusions have been achieved.
基金supported by National Natural Science Foundation of China (NSFC) (No. 61804103)National Key R&D Program of China (No. 2017YFA0205002)+8 种基金Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Nos. 18KJA535001 and 14KJB 150020)Natural Science Foundation of Jiangsu Province of China (Nos. BK20170343 and BK20180242)China Postdoctoral Science Foundation (No. 2017M610346)State Key Laboratory of Silicon Materials, Zhejiang University (No. SKL2018-03)Nantong Municipal Science and Technology Program (No. GY12017001)Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University (KSL201803)supported by Collaborative Innovation Center of Suzhou Nano Science & Technology, the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 ProjectJoint International Research Laboratory of Carbon-Based Functional Materials and Devices
文摘Continuous deforming always leads to the performance degradation of a flexible triboelectric nanogenerator due to the Young’s modulus mismatch of different functional layers.In this work,we fabricated a fiber-shaped stretchable and tailorable triboelectric nanogenerator(FST-TENG)based on the geometric construction of a steel wire as electrode and ingenious selection of silicone rubber as triboelectric layer.Owing to the great robustness and continuous conductivity,the FST-TENGs demonstrate high stability,stretchability,and even tailorability.For a single device with ~6 cm in length and ~3 mm in diameter,the open-circuit voltage of ~59.7 V,transferred charge of ~23.7 nC,short-circuit current of ~2.67 μA and average power of ~2.13 μW can be obtained at 2.5 Hz.By knitting several FST-TENGs to be a fabric or a bracelet,it enables to harvest human motion energy and then to drive a wearable electronic device.Finally,it can also be woven on dorsum of glove to monitor the movements of gesture,which can recognize every single finger,different bending angle,and numbers of bent finger by analyzing voltage signals.
文摘BACKGROUND Conventionally, the low luminous intensity, low image resolution, and difficulty in operation have been reported with the ultrathin endoscope. However, it has markedly advanced recently. The improvement of the diagnostic ability is expected.AIM To compare the early gastric cancer diagnostic ability of an ultrathin endoscope loaded with a laser light source and that of the conventional endoscope.METHODS The target subjects were 375 consecutive patients who underwent endoscopy at our hospital for post-endoscopic submucosal dissection follow-up of gastric cancer from January to August 2018. During endoscopy, the ultrathin endoscope was used in 140 patients(37.3%), and the conventional endoscope was used in235 patients(62.7%). Patient background was adjusted using the propensity score matching method, and gastric cancer detection ability was evaluated in the two groups.RESULTS The gastric cancer detection rate was 7.8% in the ultrathin endoscope group and7.0% in the conventional endoscope group, and the mean intragastric observation time was 4.1 ± 1.7 min in the ultrathin endoscope group and 4.1 ± 1.9 min in the conventional endoscope group, showing no significant differences between the groups. Moreover, the biopsy implementation rate was 31.8% in the ultrathin endoscope group and 41.1% in the conventional endoscope group, and the biopsy prediction rate was 17.9% and 13.2%, respectively, showing no significant differences between the groups.CONCLUSION The gastric cancer diagnostic ability of the ultrathin endoscope loaded with a laser light source was comparable to that of the conventional endoscope. The observation time was also comparable. Thus, endoscopy using the ultrathin endoscope loaded with the laser light source would be the first option in screening examinations of gastric cancer due to its low invasion.
基金jointly sponsored by the National Key Research and Development Plan(2018YFC1503200)National Natural Science Foundation of China(41674061,41474058 and 41790463)the Special Fund of the Institute of Geophysics,China Earthquake Administration(DQJB19B25)
文摘Active seismic sources are critical for obtaining high resolution images of the subsurface.For active imaging in urban areas,environment friendly and green seismic sources are required.In present work,we introduce a new type of green active source based on the gaseous detonation of methane and oxygen.When fired in a closed container,the chemical reaction,i.e.gaseous detonation,will produce high pressure air over 150 MPa.Seismic waves are produced when high pressure air is quickly released to impact the surroundings.The first field experiment of this active source was carried out in December,2017 in Jingdezhen,Jiangxi Province,where a series of active sources were excited to explore their potential in mine exploration.In current work,we analyzed the seismic waves recorded by near-field accelerators and a dense short-period seismic array and compared them with those from a mobile airgun source,another kind of active source by releasing high pressure air into water.The results demonstrate that it can be used for high resolution near surface imaging.Firstly,the gaseous detonation productions are harmless CO2 and water,making it a green explosive source.Secondly,the dominant seismic frequencies are 10-80 Hz and a single shot can be recorded up to 15 km,making it suitable for local structure investigations.Thirdly,it can be excited in vertical wells,similar to traditional powder explosive sources.It can also act as an additional on-land active source to airgun sources,which requires a suitable water body as intermediate media to generate repeating signals.Moreover,the short duration and high frequency signature of the source signals make it safe with no damage to nearby buildings.These make it convenient to excite in urban areas.As a new explosive source,the excitation equipment and conditions,such as gas ratio,sink depth and air-releasing directions,need further investigation to improve seismic wave generation efficiency.
文摘A method based on multiple images captured under different light sources at different incident angles was developed to recognize the coal density range in this study.The innovation is that two new images were constructed based on images captured under four single light sources.Reconstruction image 1 was constructed by fusing greyscale versions of the original images into one image,and Reconstruction image2 was constructed based on the differences between the images captured under the different light sources.Subsequently,the four original images and two reconstructed images were input into the convolutional neural network AlexNet to recognize the density range in three cases:-1.5(clean coal) and+1.5 g/cm^(3)(non-clean coal);-1.8(non-gangue) and+1.8 g/cm^(3)(gangue);-1.5(clean coal),1.5-1.8(middlings),and+1.8 g/cm^(3)(gangue).The results show the following:(1) The reconstructed images,especially Reconstruction image 2,can effectively improve the recognition accuracy for the coal density range compared with images captured under single light source.(2) The recognition accuracies for gangue and non-gangue,clean coal and non-clean coal,and clean coal,middlings,and gangue reached88.44%,86.72% and 77.08%,respectively.(3) The recognition accuracy increases as the density moves further away from the boundary density.
基金sponsored by the National Key Research and Development Project(2018YFC1503202-01)the Emergency Management Project of the National Natural Science Foundation of China(41842042)
文摘In seismic data processing,picking of the P-wave first arrivals takes up plenty of time and labor,and its accuracy plays a key role in imaging seismic structures.Based on the convolution neural network(CNN),we propose a new method to pick up the P-wave first arrivals automatically.Emitted from MINI28 vibroseis in the Jingdezhen seismic experiment,the vertical component of seismic waveforms recorded by EPS 32-bit portable seismometers are used for manually picking up the first arrivals(a total of 7242).Based on these arrivals,we establish the training and testing sets,including 25,290 event samples and 710,616 noise samples(length of each sample:2 s).After 3,000 steps of training,we obtain a convergent CNN model,which can automatically classify seismic events and noise samples with high accuracy(>99%).With the trained CNN model,we scan continuous seismic records and take the maximum output(probability of a seismic event)as the P-wave first arrival time.Compared with STA/LTA(short time average/long time average),our method shows higher precision and stronger anti-noise ability,especially with the low SNR seismic data.This CNN method is of great significance for promoting the intellectualization of seismic data processing,improving the resolution of seismic imaging,and promoting the joint inversion of active and passive sources.
基金sponsored by the Special Fund for Earthquake Scientific Research in the Public Welfare of CEA(201308011)
文摘The exciting source of the active source repeated monitoring is located in the Xiliushui Reservoir in Zhangye,Gansu Province. The system began operating normally on July 9,2015,and we had completed a period of 40 days of continuous excitation experiment before November 10,2015. Our results reveal that the airgun source has good consistency and repeatability,and the detective system of active source can record signal clearly. The construction of active source repeated exploration projects has achieved some results,which can provide valuable experience for the research of active source repeated exploration. The observation data we obtained makes it possible to follow the temporal and spatial variations of the deep structure of the Qilian Mountain areas.
基金supported by the Key Research and Development Project of the Ministry of Science and Technology(Grant No.2018YFC1503400)。
文摘The Anninghe fault is a large left-lateral strike-slip fault in southwestern China. It has controlled deposition and magmatic activities since the Proterozoic, and seismic activity occurs frequently. The Mianning-Xichang segment of the Anninghe fault is a seismic gap that has been locked by high stress. Many studies suggest that this segment has great potential for large earthquakes(magnitude >7). We obtained three vertical velocity profiles of the Anninghe fault(between Mianning and Xichang) based on the inversion of P-wave first arrival times. The travel time data were picked from seismograms generated by methane gaseous sources and recorded by three linearly distributed across-fault dense arrays. The inversion results show that the P-wave velocity structures at depths of 0-2 km corresponds well with the local lithology. The Quaternary sediments have low seismic velocities, whereas the igneous rocks,metamorphic rocks, and bedrock have high seismic velocities. We then further discuss the fault activities of the two fault branches of the Anninghe fault in the study region based on small earthquakes(magnitudes between ML 0.5 and ML 2.5) detected by the Xichang array.The eastern fault branch is more active than the western branch and that the fault activities in the eastern branch are different in the northern and southern segments at the border of 28°21′N. The high-resolution models obtained are essential for future earthquake rupture simulations and hazard assessments of the Anninghe fault zone. Future studies of velocity models at greater depths may further explain the complex fault activities in the study region.
文摘The seismic waveforms may present subtle changes related to the external loadings such as earthquakes(Pei Shunping et al.,2019)and landslides(Larose E.et al.,2015).Monitoring subtle changes provides a complementary tool for studying the dynamic processes(e.g.,Niu Fenglin et al.,2008),which has long been a major subject in seismology.The subsurface can be monitored by using natural repetitive events including repeated earthquakes(e.g.,Song Xiaodong et al.,1996)and ambient seismic noises(e.g.,Mao Shujuan et al.,2019).
基金financial support by "the Fundamental Research Funds for the Central Universities"
文摘We tested 288 pieces of the polished cabochon jadeite-jade with high quality green and smooth surfaces using the colorimeter Color i5 based on the CIE 1976 L~*a~*b~* uniform color space. The color changes after alternating three CIE standard light sources D_(65),A and CWF were compared,and the degree of metamerism was evaluated. The results show that the CIE standard light sources D_(65),A and CWF increase the chroma of green and turn bluish green into vivid green,which are similar or to nearly colorless and transparent glass-like samples with fine textures. When the three light sources were individually alternated,the lightness of the jadeite-jades showed little change,but the tone changed significantly. Metamerism occurred only in 3 pairs among the 16 samples that were selected by cluster analysis for quality,and the metamerism colors were highly consistent of L~*D_(65)∈(43.47,46.75),C~*D_(65)∈(65.20,68.80) and ho~*D_(65)∈(138.10,140.23). We can conclude that the jadeite-jade green gradually turns to blue when the color temperature of the light source increases. But when considering both the light sources and the samples,D_(65) is more suitable to be the light source of jadeite-jade green when compared with the light sources CWF and A. Compared with the CIE standard green and high chroma green,high-quality jadeite-jade green has a slight yellow tone,low lightness and high chroma. The special metamerism index decreased to 1 when the light source alternated among D_(65),A and CWF. Therefore,the color of jadeite-jade green might be slightly influenced by alternating of the light sources.
基金supported by the Guangdong Basic and Application Basic Research Foundation of Guangdong Province (Nos. 2021A1515111149, 2021B1515120022, 2020B 010174003)。
文摘With the epidemic of the coronavirus disease(COVID-19) infection, AlGaN-based ultraviolet-C light emitting diodes(UVC-LEDs) have attracted widespread attention for their sterilization application. However, the sterilization characters of high power integrated light sources(ILSs) haven’t been widely investigated before utilizing in public sanitary security. In this work,by integrating up to 195 UVC-LED chips, high power UVC-LED ILSs with a light output power(LOP) of 1.88 W were demonstrated. The UVC-LED ILSs were verified to have efficient and rapid sterilization capability, which have achieved more than99.9% inactivation rate of several common pathogenic microorganisms within 1 s. In addition, the corresponding air sterilization module based on them was also demonstrated to kill more than 97% of Staphylococcus albus in the air of 20 m3 confined room within 30 min. This work demonstrates excellent sterilization ability of UVC-LED ILSs with high LOP, revealing great potential of UVC-LEDs in sterilization applications in the future.
基金This research was supported by the National Key R&D Program of China(No.2018YFC1503200)the Nuclear Waste Geological Disposal Project([2013]727)+2 种基金the National Natural Science Foundation of China(Grant Nos.41790463 and 41730425)the Spark Program of Earthquake Sciences of CEA(XH18063Y)the Special Fund of GEC of CEA(YFGEC2017003,SFGEC2014006).
文摘In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body,two active source seismic profles were arranged near a small town named Tamusu,Western China.The study area is with complex surface conditions,thus the seismic exploration encountered a variettraveltimey of technical difculties such as crossing obstacles,de-noising harmful scattered waves,and building complex near-surface velocity models.In order to address those problems,techniques including cross-obstacle seismic geometry design,angle-domain harmful scattered noise removal,and an acoustic wave equation-based inversion method jointly utilizing both the and waveform of frst arrival waves were adopted.The fnal seismic images clearly exhibit the target rock’s unconformable contact boundary and its top interface beneath the sedimentary and weathered layers.On this basis,it could be confrmed that the target rock is not thin or has been transported by geological process from somewhere else,but a native and massive rock.There are a few small size fractures whose space distribution could be revealed by seismic images within the rock.The fractures should be kept away.Based on current research,it could be considered that active source seismic exploration is demanded during the sitting process of the geological disposal repository for nuclear waste.The seismic acquisition and processing techniques proposed in the present paper would ofer a good reference value for similar researches in the future.
文摘A visible-light photocatalyst was prepared by calcination of the hydrolysis product of Ti（SO4）2 with ammonia as precipitator. The color of this photocatalyst was vivid yellow. It could absorb light under 550 nm wavelength. The crystal structure of anatase was characterized by XRD. The structure analysis result of X-ray fluorescence（XRF） shows that doped-nitrogen was presented in the sample. The photocatalytic activities were evaluated using methyl orange and phenol as model pollutants. The photocatalytic activities of samples were increasing gradually with calcination temperature from 400℃ to 700℃ under UV irradiation. It can be seen that the degradation of methyl orange follows zero-order kinetics. However, the calcination temperatures have no significant influence on the degradation of phenol under sunlight. The N-doped catalyst shows higher activity than the bare one under solar irradiation.
文摘Analyzing the information carriede by seismic waves is a major means for human beings to have an insight into the structure of the earth’s interior,and by using artificial seismic sources to excite seismic waves,we can obtain high-resolution images for the crustal and smaller scale medium.Artificial seismic exploration methods have been widely applied to fields such as
基金financed by the Ministry of Land and Resources of China (2004DKA20280-2-5)International Sciences and Technology cooperation (2006DFA21340)+5 种基金the special funds for Sciences and technology research of public welfare trades (200811021)the key innovation project for sciences and technology of Ministry of Land and Resources (1212010711813)the China Geology survey Bureau and resources land investigation project(1212010611809)the Basic outlay of scientific research work from Ministry of Science and Technology of the People's Republic of China (J0803)the National Natural Science Foundation of China (40830316 and 40874045)SINOPPROBE-Ⅱ and Open Fund (NO.GDL0603_) of Key Laboratory of Geo-detection (China University of Geosciences,Beijing),Ministry of Education"
文摘The Tibetan plateau as one of the youngest orogen on the Earth was considered as the result of continent-continent collision between the Eurasian and Indian plates.The thickness and structure of the crust beneath Tibetan plateau is essential to understand deformation behavior of the plateau.Active-source seismic profiling is most available geo-physical method for imaging the structure of the continental crust.The results from more than 25 active-sources seismic profiles carried out in the past twenty years were reviewed in this article.A preliminary cross crustal pattern of the Tibetan Pla-teau was presented and discussed.The Moho discontinuity buries at the range of 60-80 km on average and have steep ramps located roughly beneath the sutures that are compatible with the successive stacking/accretion of the former Cenozoic blocks northeastward.The deepest Moho(near 80 km) appears closely near IYS and the crustal scale thrust system beneath southern margin of Tibetan plateau suggests strong dependence on collision and non-distributed deformation there.However,the ～20 km order of Moho offsets hardly reappears in the inline section across northern Tibetan plateau.Without a universally accepted,convincing dynamic explanation model accommodated the all of the facts seen in controlled seismic sections,but vertical thickening and northeastern shorten of the crust is quite evident and interpretable to a certain extent as the result of continent-continent collision.Simultaneously,weak geophysical signature of the BNS suggests that convergence has been accommodated perhaps partially through pure-shear thickening accompanied by removal of lower crustal material by lateral escape.Recent years the result of Moho with ～7 km offset and long extend in south-dip angle beneath the east Kunlun oro-gen and a grand thrust fault at the northern margin of Qilian orogen has attract more attention to action from the northern blocks.The broad lower-velocity area in the upper-middle crust of the Lhasa block was once considered as resulted from partially melted rocks.However the low normal vP/vS ratio and the Moho stepwise rise fail to support significant partial melting in the middle-lower crust of the central-northern Tibetan plateau.Furthermore,the lower-velocity of crust occasionally disappears,and/or local thinned exhibits their non-stationary spatial distribution.
文摘The different reflection characteristics of the surface of tin steel strips and the different speeds of the tinning line demand an adaptive illumination light source for online machine vision inspection.This light source can be integrated with a time delay integration charge-coupled device(TDI CCD)to capture the images of moving objects and facilitate inspection of the surface quality of tin steel strips.On-site application show the effectiveness of the TDI camera with the adaptive illumination light source in detecting the surface defects on tin steel strips of three different materials and with different tin coating weights.
基金supported by the National Natural Science Foundation of China with Grant No.41174040the Wenchuan earthquake Fault Scientific Drilling project
文摘We continuously monitor the long-term seismic velocity variation of one of the major ruptured faults of the devastating 2008 Mw7.9 Wenchuan earthquake in China from July 2009 to January 2012,jointly using accurately controlled routinely operated signal system active source and seismic noise-based monitoring technique.Our measurements show that the temporal velocity change is not homogeneous and highly localized in the damaged fault zone and the adjacent areas.Velocity variations from the active and passive methods are quite consistent,which both are characterized by ±0.2 % seasonal variation,with peak and trough at winter and summer,respectively.The periodic velocity variation within fault zone exhibits remarkably positive correlation with barometric pressure with stress sensitivity in the order of 10-6Pa-1,suggesting that the plausible mechanism might be the crack density variation of the shallow subsurface medium of the damaged fault zone in response to the cyclic barometric pressure loading.
基金supported by the National Key Technologies R&D Program of China(Grant No.2018YFA0306101)the Key R&D Program of Guangdong Province(Grant No.2018B030329001)+1 种基金the Scientific instrument developing project of the Chinese Academy of Science(Grant No.YJKYYQ20170032)the National Natural Science Foundation of China(Grant No.61505196)
文摘A brief introduction of semiconductor self-assembled quantum dots (QDs) applied in single-photon sources is given. Single QDs in confined quantum optical microcavity systems are reviewed along with their optical properties and coupling characteristics. Subsequently, the recent progresses in In(Ga)As QDs systems are summarized including the preparation of quantum light sources, multiple methods for embedding single QDs into different microcavities and the scalability of single-photon emitting wavelength. Particularly, several In(Ga)As QD single-photon devices are surveyed including In(Ga)As QDs coupling with nanowires, InAs QDs coupling with distributed Bragg reflection microcavity and the In(Ga)As QDs coupling with micropillar microcavities. Furthermore, applications in the field of single QDs technology are illustrated, such as the entangled photon emission by spontaneous parametric down conversion, the single-photon quantum storage, the chip preparation of single-photon sources as well as the single-photon resonance-fluorescence measurements.
文摘A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequency con-verter is obtained with low switching frequency converter. It is very promising in current-source APF that adopt super-conducting magnetic energy storage component.
