When evaluating an area's seismic risk or resilience,it is necessary to use the spatial correlation to analyze the ground motion parameters of multiple sites together in an earthquake.These two large earthquakes i...When evaluating an area's seismic risk or resilience,it is necessary to use the spatial correlation to analyze the ground motion parameters of multiple sites together in an earthquake.These two large earthquakes in Türkiye provided the possibility for spatial correlation analysis of ground motion intensity measurements in this area.Based on the strong motion records provided by The Disaster and Emergency Management Authority of Türkiye(AFAD),this study uses the local ground motion prediction equation in Türkiye to give spatial correlation analysis of Intensity Measurements.This study gives an exponential model based on a semivariogram and compares it with the correlation model obtained from previous studies.展开更多
To enhance the capacity of the radar-reconnaissance interception receiver recognizing linear frequency modulated (LFM) at a low signal-noise ratio, this paper presents WignerHough transform (WHT) of the LFM signal and...To enhance the capacity of the radar-reconnaissance interception receiver recognizing linear frequency modulated (LFM) at a low signal-noise ratio, this paper presents WignerHough transform (WHT) of the LFM signal and its corresponding characteristics, derives the probability density functions of the LFM signal and Gaussian white noise within WHT based on entropy (WHTE), dimension under different assumptions and puts forward a WHT algorithm based on entropy of slice to improve the capacity of detecting the LFM signal. Entropy of the WHT domain slice is adopted to assess the information size of polar radius or angle slice, which is converted into the weight factor to weight every slice. Double-deck weight is used to weaken the influences of noise and disturbance terms and WHTE treatment and signal detection procedure are also summarized. The rationality of the algorithm is demonstrated through theoretical analysis and formula derivation, the efficiency of the algorithm is verified by simulation comparison between WHT, fractional Fourier transform and periodic WHT, and it is highlighted that the WHTE algorithm has better detection accuracy and range of application against strong noise background.展开更多
This research was undertaken to clarify the characteristics of vegetation change and its main influencing factors on the Qinghai-Tibet Plateau. Using the greenness rate of change(GRC) and correlation factors, we analy...This research was undertaken to clarify the characteristics of vegetation change and its main influencing factors on the Qinghai-Tibet Plateau. Using the greenness rate of change(GRC) and correlation factors, we analyzed the trend of vegetation change and its dominant factors from 2000 to 2015. The results indicate that the vegetation tended to improve from 2000 to 2015 on the Qinghai-Tibet Plateau, with the improved area accounting for 39.93% of the total; and the degraded area accounting for 19.32%. The areas of degraded vegetation are mainly concentrated in the low-relief and intermediate-relief mountains of the high-altitude and extremely high-altitude areas on the Qinghai-Tibet Plateau, as the vegetation characteristics are impacted by the terrain. Temperature and precipitation have obvious response mechanisms to vegetation growth, but the effects of precipitation and temperature on vegetation degradation are not significant over a short time frame. Overgrazing and population growth are the dominant factors of vegetation degradation on the Qinghai-Tibet Plateau.展开更多
Coal bump refers to a sudden catastrophic failure of coal seam and usually can cause serious damages to underground mining facilities and staff. In this circumstance, this paper focuses on the recent achievements in t...Coal bump refers to a sudden catastrophic failure of coal seam and usually can cause serious damages to underground mining facilities and staff. In this circumstance, this paper focuses on the recent achievements in the mechanism and prevention techniques of coal bumps over the past five years in China.Based on theoretical analysis, laboratory experiment, numerical simulation and field test, the characteristics of coal bumps occurrence in China's coal mines were described, and the difference between coal bumps and rockbursts was also discussed. In addition, three categories of coal bumps induced by'material failure' were introduced, i.e. hard roof, floor strata and tectonic structures, in which the mechanism of coal bumps induced by geological structures was analyzed. This involves the bump liability and microstructure effects on bump-prone coal failure, the mechanism of coal bumps in response to fault reactivation, island face mining or hard roof failure. Next, the achievements in the monitoring and controlling methods of coal bumps were reviewed. These methods involve the incorporated prediction system of micro-seismicity and mining-induced pressure, the distributed micro-seismic monitoring system, energy absorption support system, bolts with constant resistance and large elongation,and the 'multi-stage' high-performance support. Finally, an optimal mining design is desirable for the purpose of coal bump mitigation.展开更多
It is well known that the complicated channeling of fluid flow and heat transfer is strongly related with the intricate natural fracture system.However,it is still challenging to set up the fracture network model whic...It is well known that the complicated channeling of fluid flow and heat transfer is strongly related with the intricate natural fracture system.However,it is still challenging to set up the fracture network model which is strong heterogeneous.Compared with other methods(e.g.equivalent continuum model(ECM),discrete fracture model(DFM),and ECM-DFM),the fracture flow module in the COMSOL Multiphysics simulator is powerful in definition of fractures as the inner flow boundary existing in the porous media.Thus it is selected to simulate the fluid flow and heat transfer in the geothermal-developed fractured granite of Sanguliu area located at Liaodong Peninsula,Eastern China.The natural faults/fractures based on field investigation combined with the discrete fracture network(DFN)generated by the MATLAB are used to represent the two-dimensional geological model.Numerical results show that early thermal breakthrough occurs at the production well caused by quick flow of cold water along the highly connected fractures.Suitable hydraulic fracturing treatments with proper injection rates,locations,etc.can efficiently hinder the thermal breakthrough time in the natural fracture system.Large well spacing helps the long-term operation of geothermal production,but it is highly dependent on the geometrical morphology of the fracture network.The enhancement of reservoir properties at the near-well regions can also increase the geothermal production efficiency.The results in this study can provide references to achieve a sustainable geothermal exploitation in fractured granitic geothermal reservoirs or hot dry rocks at depth.展开更多
It is generally recognized that Caucasians and Asians have different skin aging features. The aim of this study was to develop a facial wrinkle grading scale for Chinese women. Standard photographs were taken of 242 C...It is generally recognized that Caucasians and Asians have different skin aging features. The aim of this study was to develop a facial wrinkle grading scale for Chinese women. Standard photographs were taken of 242 Chinese women. Six sets of 0 to 9 wrinkle scales with reference photographs and descriptions were selected, including grading scales for resting and hyperkinetic crow's feet, frontalis lines, glabellar frown lines, and nasolabial folds. To identify the scale by objective quantitative measurement, skin surface measurements from the Visioscan~ VC98 were used. To test the reliability and validity of our wrinkle scale, a multi-rater consensus method was used. A double-blind, randomized, vehicle-controlled 12-week study was conducted to use this clinical photo-score to evaluate the efficacy and safety of Centella triterpenes cream~ in treating crow's feet. A newly developed 10-point photographic and descriptive scale emerged from this study. The final atlas of these photographs contained a total of 6 sets with 10 pictures each. From 0 to 9, surface evaluation of smoothness (SEsm) parametric measurements decreased progressively, indicating that the scale increased inversely. Weighted kappa coefficients for intra-assessor were between 0.75-0.87. The overall Kendall's coefficient is 0.86 on the first rating and 0.87 on the second rating. Thirty- six volunteers were recruited and 35 subjects completed a 12-week trial. Clinical photo-score by investigator showed a significant difference (P 〈 0.05) between the treatment side and control side after 4 weeks. Use of these scales in clinical settings to evaluate facial wrinkles in Asians individuals is recommended.展开更多
Visualization of complex geological structures can technically support the accurate prediction and prevention of coal mine disasters.This study proposed a new digital reconstruction method to visualize geological stru...Visualization of complex geological structures can technically support the accurate prediction and prevention of coal mine disasters.This study proposed a new digital reconstruction method to visualize geological structures based on establishing a virtual model in the digital twin system.This methodology for the digital reconstruction of complex fault structures comprises the following four aspects:(1)collection and fdelity of multi-physical feld data of the fault structures,(2)the transmission of multi-physical feld data,(3)the normalization of multi-physical feld data,and(4)digital model reconstruction of fault structures.The key scientifc issues of this methodology to be resolved include in situ fdelity of multi-feld data and normalized programming of multi-source data.In addition,according to the geological background and conditions in Da’anshan coal mine in western Beijing,China,a preliminary attempt is made to reconstruct a digital model of fault and fold structures using the methodology proposed in this study.展开更多
The Ludian County of Yunnan Province in southwestern China was struck by an Ms6.5 earthquake on August 3, 2014, which was another destructive event following the Ms8.0 Wenchuan earthquake in 2008, Ms7.1 Yushu earthqua...The Ludian County of Yunnan Province in southwestern China was struck by an Ms6.5 earthquake on August 3, 2014, which was another destructive event following the Ms8.0 Wenchuan earthquake in 2008, Ms7.1 Yushu earthquake in 2010, and Ms7.0 Lushan earthquake in 2013. National Strong-Motion Observation Network System of China collected 74 strong motion recordings, which the maximum peak ground acceleration recorded by the 053LLT station in Longtoushan Town was 949 cm/s2 in E-W component. The observed PGAs and spectral ordinates were compared with ground-motion prediction equation in China and the NGA-West2 developed by Pacific Earthquake Engineering Researcher Center. This earthquake is considered as the first case for testing applicability of NGA-West2 in China. Results indicate that the observed PGAs and the 5 % damped pseudo-response spectral accelerations are significantly lower than the pre- dicted ones. The field survey around some typical strong motion stations verified that the earthquake damage was consistent with the official isoseismal by China Earthquake Administration.展开更多
In this paper, diamond-like carbon (DLC) films were deposited on Ti alloy by electro-deposition. DLC films were brown andcomposed of the compact grains whose diameter was about 400 nm. Examined by XPS, the main compos...In this paper, diamond-like carbon (DLC) films were deposited on Ti alloy by electro-deposition. DLC films were brown andcomposed of the compact grains whose diameter was about 400 nm. Examined by XPS, the main composition of the filmswas carbon. In the Raman spectrum, there were a broad peak at 1350 cm^(-1) and a broad peak at 1600 cm^(-1), which indicatedthat the films were DLC films.展开更多
The neutron capture cross section of ^(232)Th was measured at the neutron time-of-flight facility Back-n of China Spallation Neutron Source(CSNS)for the first time.The measurement was performed with 4 hydrogen-free de...The neutron capture cross section of ^(232)Th was measured at the neutron time-of-flight facility Back-n of China Spallation Neutron Source(CSNS)for the first time.The measurement was performed with 4 hydrogen-free deuterated benzene C6D6 liquid scintillation detectors,in the ES#2 experiment station on the beam line,at a distance of about 76 m from the neutron-production assembly.The total energy detection principle in combination with the pulse height weighting technique(PHWT)was applied to analyze the measured data.Results of the ^(232)Th(n,γ)reaction cross section in the unresolved resonance region from 4 keV to 100 keV were obtained,which shows a good agreement with the existing experimental data from EXFOR,as well as with the evaluated data from the ENDF/B-VIII.0 and CENDL-3.1.In addition,the excitation function of ^(232)Th(n,γ)^(233)Th reaction in the unresolved resonance region was theoretically calculated by using the code TALYS-1.95.By fitting the experimental cross section and theoretical data,the average parameters in the unresolved resonance region were extracted.展开更多
Structured illumination microscopy(SIM)is a rapidly developing super-resolution technology.It has been widely used in various application fields of biomedicine due to its excellent two-and three-dimensional imaging ca...Structured illumination microscopy(SIM)is a rapidly developing super-resolution technology.It has been widely used in various application fields of biomedicine due to its excellent two-and three-dimensional imaging capabilities.Furthermore,faster three-dimensional imaging methods are required to help enable more research-oriented living cell imaging.In this paper,a fast and sensitive three-dimensional structured illumination microscopy based on asymmetric three-beam interference is proposed.An innovative time-series acquisition method is employed to halve the time required to obtain each raw image.A segmented half-wave plate as a substantial linear polarization modulation method is applied to the three-dimensional SIM system for the first time.Although it needs to acquire 21 raw images instead of 15 to reconstruct one super-resolution image,the SIM setup proposed in this paper is 30%faster than the traditional spatial light modulator-SIM(SLM-SIM)in imaging each super-resolution image.The related theoretical derivation,hardware system,and verification experiment are elaborated in this paper.The stable and fast 3D super-resolution imaging method proposed in this paper is of great significance to the research of organelle interaction,intercellular communication,and other biomedical fields.展开更多
A new Gaussian approximation nonlinear filter called generalized cubature quadrature Kalman filter (GCQKF) is introduced for nonlinear dynamic systems. Based on standard GCQKF, two extensions are developed, namely squ...A new Gaussian approximation nonlinear filter called generalized cubature quadrature Kalman filter (GCQKF) is introduced for nonlinear dynamic systems. Based on standard GCQKF, two extensions are developed, namely square root generalized cubature quadrature Kalman filter (SR-GCQKF) and iterated generalized cubature quadrature Kalman filter (I-GCQKF). In SR-GCQKF, the QR decomposition is exploited to alter the Cholesky decomposition and both predicted and filtered error covariances have been propagated in square root format to make sure the numerical stability. In I-GCQKF, the measurement update step is executed iteratively to make full use of the latest measurement and a new terminal criterion is adopted to guarantee the increase of likelihood. Detailed numerical experiments demonstrate the superior performance on both tracking stability and estimation accuracy of I-GCQKF and SR-GCQKF compared with GCQKF.展开更多
In response to the development of deep-sea oil and gas resources,which require a high degree of cooperation by crude oil transportation equipment,a new type of ship known as the cargo transfer vessel(CTV)has been deve...In response to the development of deep-sea oil and gas resources,which require a high degree of cooperation by crude oil transportation equipment,a new type of ship known as the cargo transfer vessel(CTV)has been developed.To provide a theoretical reference for the design and equipment of the CTV’s dynamic positioning system,in this paper,we take the new deepwater CTVas the study object and theoretically and numerically analyze its operation,wind load,current load,wave load,and navigational resistance in a range of Brazilian sea conditions with respect to its positioning and towing modes.We confirm that our proposed method can successfully calculate the total environmental load of the CTVand that the CTV is able to operate normally under the designed sea conditions.展开更多
This paper presents an investigation on the characteristics of overlying strata collapse and mining-induced pressure in fault-influenced zone by employing the physical modeling in consideration of fault structure. The...This paper presents an investigation on the characteristics of overlying strata collapse and mining-induced pressure in fault-influenced zone by employing the physical modeling in consideration of fault structure. The precursory information of fault slip during the underground mining activities is studied as well. Based on the physical modeling, the optimization of roadway support design and the field verification in fault-influenced zone are conducted. Physical modeling results show that, due to the combined effect of mining activities and fault slip, the mining-induced pressure and the extent of damaged rock masses in the fault-influenced zone are greater than those in the uninfluenced zone. The sharp increase and the succeeding stabilization of stress or steady increase in displacement can be identified as the precursory information of fault slip. Considering the larger mining-induced pressure in the fault-influenced zone, the new support design utilizing cables is proposed. The optimization of roadway support design suggests that the cables can be anchored in the stable surrounding rocks and can effectively mobilize the load bearing capacity of the stable surrounding rocks. The field observation indicates that the roadway is in good condition with the optimized roadway support design.展开更多
In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–...In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.展开更多
Photodynamic therapy(PDT)has received increased attention since the regulatory approvals of several photosensitizers and light applicators in numerous countries and regions around the world.In recent years,much progre...Photodynamic therapy(PDT)has received increased attention since the regulatory approvals of several photosensitizers and light applicators in numerous countries and regions around the world.In recent years,much progress has been seen in basic research as well as clinical application.PDT clinical application has now extended from treating malignant diseases to nonmalignant diseases.This review article will present recent clinical data published in English journals.The data will be organized according to their clinical specialties.The new development and future direction in clinical applications of PDT for the management of both malignant and nonmalignant diseases will be discussed.展开更多
The stochastic finite-fault simulation method was applied to synthesize the horizontal ground acceleration seismograms produced by the MW6.1 Ludian earthquake on August 3,2014.For this purpose,we produced first a tota...The stochastic finite-fault simulation method was applied to synthesize the horizontal ground acceleration seismograms produced by the MW6.1 Ludian earthquake on August 3,2014.For this purpose,we produced first a total of 200 kinematic source models for the Ludian event,which are characterized by the heterogeneous slip on the conjugated ruptured fault and the slip-dependent spreading of the rupture front.The results indicated that the heterogeneous slip and the spatial extent of the ruptured fault play dominant roles in the spatial distribution of ground motions in the near-fault area.The peak ground accelerations(PGAs)and 5%-damped pseudospectral accelerations(PSAs)at periods shorter than 0.5 s estimated on the resulting synthetics generally match well with the observations at stations with Joyner-Boore distances(RJB)greater than 20 km.The synthetic PGVs and PSAs at periods of 0.5 s and 0.75 s are in good agreement with predicted medians by the Yu14 model(Yu et al.,2014).However,the synthetic results are generally much lower than the predicted medians by BSSA14 model(Boore et al.,2014).Moreover,the ground motion variability caused by the randomness in the source rupture process was evaluated by these synthetics.The standard deviations of PSAs on the base-10 logarithmic scale,Sigma[log10(PSA)],are closely dependent on either the spectral period or the RJB.The Sigma[log10(PSA)]remains a constant approximately 0.55 at periods shorter than 0.1 s,and then increase continuously up to^0.13 as the period increases from 0.1 to 2.0 s.The Sigma[log10(PSA)]values at periods of 0.1‒2.0 s show the downward tendency as the RJB values increase.However,the Sigma[log10(PSA)]values at periods shorter than 0.1 s decrease as the RJB values increase up to^50 km,and then increase with the increasing RJB.Furthermore,we found that the ground-motion variability shows the significant dependence on the azimuth.展开更多
In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southe...In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southern margin of the Eastern Asia latitudinal permafrost body. Under a warming climate, permafrost undergoes rapid and extensive degradation. In this study, the frost-number (Fn) model based on air temperatures and ground surface temperatures was used to predict the distribution of the Xing’an permafrost, and, temporal and spatial changes in air and ground-surface temperatures from 1961 to 2019 are analyzed. The results show that Northeast China has experienced a rapid and substantial climate warming over the past 60 years. The rises in mean annual air and mean annual ground-surface temperatures were higher in permafrost zones than those in the seasonal frost zone. The frost numbers of air and ground-surface temperatures were calculated for determining the southern limit of latitudinal permafrost and for permafrost zonation. The southern limits of discontinuous permafrost, sporadic permafrost, and latitudinal permafrost moved northward significantly. According to the air-temperature frost-number criteria for permafrost zoning, compared with that in the 1960s, the extent of Xing’an permafrost in Northeast China had decreased by 40.6% by the 2010s. With an average rate of increase in mean annual air temperatures at 0.03 ℃ a^(−1), the extent of permafrost in Northeast China will decrease to 26.42 × 10^(4) by 2020, 14.69 × 10^(4) by 2040 and to 11.24 × 10^(4) km^(2) by 2050. According to the ground-surface temperature frost-number criteria, the southern limit of latitudinal permafrost was at the 0.463. From the 1960s to the 2010s, the extent of latitudinal permafrost declined significantly. Due to the nature of the ecosystem-protected Xing’an-Baikal permafrost, management and protection (e.g., more prudent and effective forest fire management and proper logging of forests) of the Xing’an permafrost eco-environment should be strengthened.展开更多
Arousing funders’motives for crowdfunding participation is a challenge for every entrepreneur.According to self-determination theory,crowdfunding involvement is driven by two kinds of motivations:extrinsic and intrin...Arousing funders’motives for crowdfunding participation is a challenge for every entrepreneur.According to self-determination theory,crowdfunding involvement is driven by two kinds of motivations:extrinsic and intrinsic motives.Campaign narratives with different sentimental orientations could act as cues triggering funders’motives of capital-giving differently.Thus,we focus on the moderating effect of text sentiment on the motivational cues in crowdfunding campaigns.We hypothesize that the sentiment of campaign narratives moderates the relationship between motivational cues and fundraising success.Data are selected from 270,000 campaigns of the crowdfunding website Indiegogo.Empirical analysis demonstrates that the sentiment strength positively moderates the effect of intrinsic motives on fundraising success but negatively moderates the impact of extrinsic motives on fundraising success.The findings provide managerial insights for practitioners to stimulate specified motives by using the narratives with proper sentiment strength.展开更多
基金jointly supported by the National Natural Science Foundation of China U1901602,U2239252)the National Key R&D Program of China(No.2019YFE0115700)+1 种基金the Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration(Grant No.2021EEEVL0202)the Natural Science Foundation of Heilongjiang Province(LH2020E021)。
文摘When evaluating an area's seismic risk or resilience,it is necessary to use the spatial correlation to analyze the ground motion parameters of multiple sites together in an earthquake.These two large earthquakes in Türkiye provided the possibility for spatial correlation analysis of ground motion intensity measurements in this area.Based on the strong motion records provided by The Disaster and Emergency Management Authority of Türkiye(AFAD),this study uses the local ground motion prediction equation in Türkiye to give spatial correlation analysis of Intensity Measurements.This study gives an exponential model based on a semivariogram and compares it with the correlation model obtained from previous studies.
基金supported by the Aeronautical Science Fund of China(201455960252015209619)
文摘To enhance the capacity of the radar-reconnaissance interception receiver recognizing linear frequency modulated (LFM) at a low signal-noise ratio, this paper presents WignerHough transform (WHT) of the LFM signal and its corresponding characteristics, derives the probability density functions of the LFM signal and Gaussian white noise within WHT based on entropy (WHTE), dimension under different assumptions and puts forward a WHT algorithm based on entropy of slice to improve the capacity of detecting the LFM signal. Entropy of the WHT domain slice is adopted to assess the information size of polar radius or angle slice, which is converted into the weight factor to weight every slice. Double-deck weight is used to weaken the influences of noise and disturbance terms and WHTE treatment and signal detection procedure are also summarized. The rationality of the algorithm is demonstrated through theoretical analysis and formula derivation, the efficiency of the algorithm is verified by simulation comparison between WHT, fractional Fourier transform and periodic WHT, and it is highlighted that the WHTE algorithm has better detection accuracy and range of application against strong noise background.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, China (Grant No. XDA20100101)the Foundation for Excellent Youth Scholars of Northwest Institute of Eco-environment and Resources, Chinese Acad emy of Sciences (Y651K91001)
文摘This research was undertaken to clarify the characteristics of vegetation change and its main influencing factors on the Qinghai-Tibet Plateau. Using the greenness rate of change(GRC) and correlation factors, we analyzed the trend of vegetation change and its dominant factors from 2000 to 2015. The results indicate that the vegetation tended to improve from 2000 to 2015 on the Qinghai-Tibet Plateau, with the improved area accounting for 39.93% of the total; and the degraded area accounting for 19.32%. The areas of degraded vegetation are mainly concentrated in the low-relief and intermediate-relief mountains of the high-altitude and extremely high-altitude areas on the Qinghai-Tibet Plateau, as the vegetation characteristics are impacted by the terrain. Temperature and precipitation have obvious response mechanisms to vegetation growth, but the effects of precipitation and temperature on vegetation degradation are not significant over a short time frame. Overgrazing and population growth are the dominant factors of vegetation degradation on the Qinghai-Tibet Plateau.
基金supported by the National Key Research and Development Program (Grant No. 2016YFC0801401)National Natural Science Foundation of China (Grant No. 41502184)Beijing Natural Science Foundation (Grant No. 2164067)
文摘Coal bump refers to a sudden catastrophic failure of coal seam and usually can cause serious damages to underground mining facilities and staff. In this circumstance, this paper focuses on the recent achievements in the mechanism and prevention techniques of coal bumps over the past five years in China.Based on theoretical analysis, laboratory experiment, numerical simulation and field test, the characteristics of coal bumps occurrence in China's coal mines were described, and the difference between coal bumps and rockbursts was also discussed. In addition, three categories of coal bumps induced by'material failure' were introduced, i.e. hard roof, floor strata and tectonic structures, in which the mechanism of coal bumps induced by geological structures was analyzed. This involves the bump liability and microstructure effects on bump-prone coal failure, the mechanism of coal bumps in response to fault reactivation, island face mining or hard roof failure. Next, the achievements in the monitoring and controlling methods of coal bumps were reviewed. These methods involve the incorporated prediction system of micro-seismicity and mining-induced pressure, the distributed micro-seismic monitoring system, energy absorption support system, bolts with constant resistance and large elongation,and the 'multi-stage' high-performance support. Finally, an optimal mining design is desirable for the purpose of coal bump mitigation.
基金financial support from the projects of the National Natural Science Foundation of China(NSFC)(Grant Nos.51809259,51774056,and 51774095)the CAS Pioneer Hundred Talents Program in China。
文摘It is well known that the complicated channeling of fluid flow and heat transfer is strongly related with the intricate natural fracture system.However,it is still challenging to set up the fracture network model which is strong heterogeneous.Compared with other methods(e.g.equivalent continuum model(ECM),discrete fracture model(DFM),and ECM-DFM),the fracture flow module in the COMSOL Multiphysics simulator is powerful in definition of fractures as the inner flow boundary existing in the porous media.Thus it is selected to simulate the fluid flow and heat transfer in the geothermal-developed fractured granite of Sanguliu area located at Liaodong Peninsula,Eastern China.The natural faults/fractures based on field investigation combined with the discrete fracture network(DFN)generated by the MATLAB are used to represent the two-dimensional geological model.Numerical results show that early thermal breakthrough occurs at the production well caused by quick flow of cold water along the highly connected fractures.Suitable hydraulic fracturing treatments with proper injection rates,locations,etc.can efficiently hinder the thermal breakthrough time in the natural fracture system.Large well spacing helps the long-term operation of geothermal production,but it is highly dependent on the geometrical morphology of the fracture network.The enhancement of reservoir properties at the near-well regions can also increase the geothermal production efficiency.The results in this study can provide references to achieve a sustainable geothermal exploitation in fractured granitic geothermal reservoirs or hot dry rocks at depth.
文摘It is generally recognized that Caucasians and Asians have different skin aging features. The aim of this study was to develop a facial wrinkle grading scale for Chinese women. Standard photographs were taken of 242 Chinese women. Six sets of 0 to 9 wrinkle scales with reference photographs and descriptions were selected, including grading scales for resting and hyperkinetic crow's feet, frontalis lines, glabellar frown lines, and nasolabial folds. To identify the scale by objective quantitative measurement, skin surface measurements from the Visioscan~ VC98 were used. To test the reliability and validity of our wrinkle scale, a multi-rater consensus method was used. A double-blind, randomized, vehicle-controlled 12-week study was conducted to use this clinical photo-score to evaluate the efficacy and safety of Centella triterpenes cream~ in treating crow's feet. A newly developed 10-point photographic and descriptive scale emerged from this study. The final atlas of these photographs contained a total of 6 sets with 10 pictures each. From 0 to 9, surface evaluation of smoothness (SEsm) parametric measurements decreased progressively, indicating that the scale increased inversely. Weighted kappa coefficients for intra-assessor were between 0.75-0.87. The overall Kendall's coefficient is 0.86 on the first rating and 0.87 on the second rating. Thirty- six volunteers were recruited and 35 subjects completed a 12-week trial. Clinical photo-score by investigator showed a significant difference (P 〈 0.05) between the treatment side and control side after 4 weeks. Use of these scales in clinical settings to evaluate facial wrinkles in Asians individuals is recommended.
基金This study was financially supported by the Beijing Natural Science Foundation(8202041)National Natural Science Foundation of China(41872205)+1 种基金Yue Qi Young Scholar Project,China University of Mining&Technology,Beijing(2018QN13)the Fundamental Research Funds for the Central Universities(2022YJSLJ08,2021YJSLJ10).
文摘Visualization of complex geological structures can technically support the accurate prediction and prevention of coal mine disasters.This study proposed a new digital reconstruction method to visualize geological structures based on establishing a virtual model in the digital twin system.This methodology for the digital reconstruction of complex fault structures comprises the following four aspects:(1)collection and fdelity of multi-physical feld data of the fault structures,(2)the transmission of multi-physical feld data,(3)the normalization of multi-physical feld data,and(4)digital model reconstruction of fault structures.The key scientifc issues of this methodology to be resolved include in situ fdelity of multi-feld data and normalized programming of multi-source data.In addition,according to the geological background and conditions in Da’anshan coal mine in western Beijing,China,a preliminary attempt is made to reconstruct a digital model of fault and fold structures using the methodology proposed in this study.
基金supported by the Science Foundation of Institute of Engineering Mechanics, China Earthquake Administration (CEA) under Grant No. 2014B06the National Natural Science Foundation of China Nos. 51308515 and 51278473
文摘The Ludian County of Yunnan Province in southwestern China was struck by an Ms6.5 earthquake on August 3, 2014, which was another destructive event following the Ms8.0 Wenchuan earthquake in 2008, Ms7.1 Yushu earthquake in 2010, and Ms7.0 Lushan earthquake in 2013. National Strong-Motion Observation Network System of China collected 74 strong motion recordings, which the maximum peak ground acceleration recorded by the 053LLT station in Longtoushan Town was 949 cm/s2 in E-W component. The observed PGAs and spectral ordinates were compared with ground-motion prediction equation in China and the NGA-West2 developed by Pacific Earthquake Engineering Researcher Center. This earthquake is considered as the first case for testing applicability of NGA-West2 in China. Results indicate that the observed PGAs and the 5 % damped pseudo-response spectral accelerations are significantly lower than the pre- dicted ones. The field survey around some typical strong motion stations verified that the earthquake damage was consistent with the official isoseismal by China Earthquake Administration.
基金Our work is supported by the Natural Science Fund of Jiangsu Province(BK20001414).
文摘In this paper, diamond-like carbon (DLC) films were deposited on Ti alloy by electro-deposition. DLC films were brown andcomposed of the compact grains whose diameter was about 400 nm. Examined by XPS, the main composition of the filmswas carbon. In the Raman spectrum, there were a broad peak at 1350 cm^(-1) and a broad peak at 1600 cm^(-1), which indicatedthat the films were DLC films.
基金supported by the Chinese TMSR Strategic Pioneer Science and Technology Project(Grant No.XDA02010000)the National Natural Science Foundation of China(Grant No.11790321).
文摘The neutron capture cross section of ^(232)Th was measured at the neutron time-of-flight facility Back-n of China Spallation Neutron Source(CSNS)for the first time.The measurement was performed with 4 hydrogen-free deuterated benzene C6D6 liquid scintillation detectors,in the ES#2 experiment station on the beam line,at a distance of about 76 m from the neutron-production assembly.The total energy detection principle in combination with the pulse height weighting technique(PHWT)was applied to analyze the measured data.Results of the ^(232)Th(n,γ)reaction cross section in the unresolved resonance region from 4 keV to 100 keV were obtained,which shows a good agreement with the existing experimental data from EXFOR,as well as with the evaluated data from the ENDF/B-VIII.0 and CENDL-3.1.In addition,the excitation function of ^(232)Th(n,γ)^(233)Th reaction in the unresolved resonance region was theoretically calculated by using the code TALYS-1.95.By fitting the experimental cross section and theoretical data,the average parameters in the unresolved resonance region were extracted.
基金This work was funded by The National Key R&D Program of China(2016YFF0102000)Scientific Research and Equipment Development Project of CAS(YJKYYQ20180032 and YJKYYQ20190048)Major Innovative Research Team of Suzhou(ZXT2019007).
文摘Structured illumination microscopy(SIM)is a rapidly developing super-resolution technology.It has been widely used in various application fields of biomedicine due to its excellent two-and three-dimensional imaging capabilities.Furthermore,faster three-dimensional imaging methods are required to help enable more research-oriented living cell imaging.In this paper,a fast and sensitive three-dimensional structured illumination microscopy based on asymmetric three-beam interference is proposed.An innovative time-series acquisition method is employed to halve the time required to obtain each raw image.A segmented half-wave plate as a substantial linear polarization modulation method is applied to the three-dimensional SIM system for the first time.Although it needs to acquire 21 raw images instead of 15 to reconstruct one super-resolution image,the SIM setup proposed in this paper is 30%faster than the traditional spatial light modulator-SIM(SLM-SIM)in imaging each super-resolution image.The related theoretical derivation,hardware system,and verification experiment are elaborated in this paper.The stable and fast 3D super-resolution imaging method proposed in this paper is of great significance to the research of organelle interaction,intercellular communication,and other biomedical fields.
基金supported by the National Natural Science Foundation of China(6147322711472222)+2 种基金the Aerospace Technology Support Fund of China(2014-HT-XGD)the Natural Science Foundation of Shaanxi Province(2015JM6304)the Aeronautical Science Foundation of China(20151353018)
文摘A new Gaussian approximation nonlinear filter called generalized cubature quadrature Kalman filter (GCQKF) is introduced for nonlinear dynamic systems. Based on standard GCQKF, two extensions are developed, namely square root generalized cubature quadrature Kalman filter (SR-GCQKF) and iterated generalized cubature quadrature Kalman filter (I-GCQKF). In SR-GCQKF, the QR decomposition is exploited to alter the Cholesky decomposition and both predicted and filtered error covariances have been propagated in square root format to make sure the numerical stability. In I-GCQKF, the measurement update step is executed iteratively to make full use of the latest measurement and a new terminal criterion is adopted to guarantee the increase of likelihood. Detailed numerical experiments demonstrate the superior performance on both tracking stability and estimation accuracy of I-GCQKF and SR-GCQKF compared with GCQKF.
基金supported by the National Natural Science Foundation of China(Grant No.51509046)Foundation of Ministry of Industry and Information Technology High-tech Ship Scientific Research(Grant No.2016-26)
文摘In response to the development of deep-sea oil and gas resources,which require a high degree of cooperation by crude oil transportation equipment,a new type of ship known as the cargo transfer vessel(CTV)has been developed.To provide a theoretical reference for the design and equipment of the CTV’s dynamic positioning system,in this paper,we take the new deepwater CTVas the study object and theoretically and numerically analyze its operation,wind load,current load,wave load,and navigational resistance in a range of Brazilian sea conditions with respect to its positioning and towing modes.We confirm that our proposed method can successfully calculate the total environmental load of the CTVand that the CTV is able to operate normally under the designed sea conditions.
基金financially supported by the National Natural Science Foundation of China(No.41502184)Beijing Natural Science Foundation(No.2164067)+2 种基金National Key Research and Development Program(No.2016YFC0801401)Fundamental Research Funds for the Central Universities(No.2014QL01)Innovation Training Programs for Undergraduate Students(Nos.201411413054 and SKLCRSM14CXJH08)
文摘This paper presents an investigation on the characteristics of overlying strata collapse and mining-induced pressure in fault-influenced zone by employing the physical modeling in consideration of fault structure. The precursory information of fault slip during the underground mining activities is studied as well. Based on the physical modeling, the optimization of roadway support design and the field verification in fault-influenced zone are conducted. Physical modeling results show that, due to the combined effect of mining activities and fault slip, the mining-induced pressure and the extent of damaged rock masses in the fault-influenced zone are greater than those in the uninfluenced zone. The sharp increase and the succeeding stabilization of stress or steady increase in displacement can be identified as the precursory information of fault slip. Considering the larger mining-induced pressure in the fault-influenced zone, the new support design utilizing cables is proposed. The optimization of roadway support design suggests that the cables can be anchored in the stable surrounding rocks and can effectively mobilize the load bearing capacity of the stable surrounding rocks. The field observation indicates that the roadway is in good condition with the optimized roadway support design.
文摘In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.
文摘Photodynamic therapy(PDT)has received increased attention since the regulatory approvals of several photosensitizers and light applicators in numerous countries and regions around the world.In recent years,much progress has been seen in basic research as well as clinical application.PDT clinical application has now extended from treating malignant diseases to nonmalignant diseases.This review article will present recent clinical data published in English journals.The data will be organized according to their clinical specialties.The new development and future direction in clinical applications of PDT for the management of both malignant and nonmalignant diseases will be discussed.
基金supported by the Science Foundation of the Institute of Engineering Mechanics,China Earthquake Administration(No.2018B03)National Natural Science Foundation of China(No.51808514).
文摘The stochastic finite-fault simulation method was applied to synthesize the horizontal ground acceleration seismograms produced by the MW6.1 Ludian earthquake on August 3,2014.For this purpose,we produced first a total of 200 kinematic source models for the Ludian event,which are characterized by the heterogeneous slip on the conjugated ruptured fault and the slip-dependent spreading of the rupture front.The results indicated that the heterogeneous slip and the spatial extent of the ruptured fault play dominant roles in the spatial distribution of ground motions in the near-fault area.The peak ground accelerations(PGAs)and 5%-damped pseudospectral accelerations(PSAs)at periods shorter than 0.5 s estimated on the resulting synthetics generally match well with the observations at stations with Joyner-Boore distances(RJB)greater than 20 km.The synthetic PGVs and PSAs at periods of 0.5 s and 0.75 s are in good agreement with predicted medians by the Yu14 model(Yu et al.,2014).However,the synthetic results are generally much lower than the predicted medians by BSSA14 model(Boore et al.,2014).Moreover,the ground motion variability caused by the randomness in the source rupture process was evaluated by these synthetics.The standard deviations of PSAs on the base-10 logarithmic scale,Sigma[log10(PSA)],are closely dependent on either the spectral period or the RJB.The Sigma[log10(PSA)]remains a constant approximately 0.55 at periods shorter than 0.1 s,and then increase continuously up to^0.13 as the period increases from 0.1 to 2.0 s.The Sigma[log10(PSA)]values at periods of 0.1‒2.0 s show the downward tendency as the RJB values increase.However,the Sigma[log10(PSA)]values at periods shorter than 0.1 s decrease as the RJB values increase up to^50 km,and then increase with the increasing RJB.Furthermore,we found that the ground-motion variability shows the significant dependence on the azimuth.
基金The project is fully funded by the Natural Science Foundation of China Program(Grant Nos.42001052 and 41871052)Startup Research Funding of Northeast Forestry University for Chengdong Outstanding Youth Scholarship(YQ2020-10)+1 种基金Chengdong Leadership(LJ2020-01)the State Key Laboratory of Frozen Soils Engineering Open Fund Project(Grant No.SKLFSE202008).
文摘In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southern margin of the Eastern Asia latitudinal permafrost body. Under a warming climate, permafrost undergoes rapid and extensive degradation. In this study, the frost-number (Fn) model based on air temperatures and ground surface temperatures was used to predict the distribution of the Xing’an permafrost, and, temporal and spatial changes in air and ground-surface temperatures from 1961 to 2019 are analyzed. The results show that Northeast China has experienced a rapid and substantial climate warming over the past 60 years. The rises in mean annual air and mean annual ground-surface temperatures were higher in permafrost zones than those in the seasonal frost zone. The frost numbers of air and ground-surface temperatures were calculated for determining the southern limit of latitudinal permafrost and for permafrost zonation. The southern limits of discontinuous permafrost, sporadic permafrost, and latitudinal permafrost moved northward significantly. According to the air-temperature frost-number criteria for permafrost zoning, compared with that in the 1960s, the extent of Xing’an permafrost in Northeast China had decreased by 40.6% by the 2010s. With an average rate of increase in mean annual air temperatures at 0.03 ℃ a^(−1), the extent of permafrost in Northeast China will decrease to 26.42 × 10^(4) by 2020, 14.69 × 10^(4) by 2040 and to 11.24 × 10^(4) km^(2) by 2050. According to the ground-surface temperature frost-number criteria, the southern limit of latitudinal permafrost was at the 0.463. From the 1960s to the 2010s, the extent of latitudinal permafrost declined significantly. Due to the nature of the ecosystem-protected Xing’an-Baikal permafrost, management and protection (e.g., more prudent and effective forest fire management and proper logging of forests) of the Xing’an permafrost eco-environment should be strengthened.
基金supported by the Natural Science Foundation of China[71771177,72072062]Innovation Fund for University Production,Education and Research from China’s Ministry of Education[2019J01012]+1 种基金the Fundamental Research Funds for the Central Universities[22120200279]the Standardization of Trade in Service Fund(FMBZH-1947).
文摘Arousing funders’motives for crowdfunding participation is a challenge for every entrepreneur.According to self-determination theory,crowdfunding involvement is driven by two kinds of motivations:extrinsic and intrinsic motives.Campaign narratives with different sentimental orientations could act as cues triggering funders’motives of capital-giving differently.Thus,we focus on the moderating effect of text sentiment on the motivational cues in crowdfunding campaigns.We hypothesize that the sentiment of campaign narratives moderates the relationship between motivational cues and fundraising success.Data are selected from 270,000 campaigns of the crowdfunding website Indiegogo.Empirical analysis demonstrates that the sentiment strength positively moderates the effect of intrinsic motives on fundraising success but negatively moderates the impact of extrinsic motives on fundraising success.The findings provide managerial insights for practitioners to stimulate specified motives by using the narratives with proper sentiment strength.