The Directions of Arrivals （DOAs）, speeds and distances of targets are all required for array signal processing. Based on the periodic phase shift of coherent pulse sequence waveform, a new estimation of multi-targ...The Directions of Arrivals （DOAs）, speeds and distances of targets are all required for array signal processing. Based on the periodic phase shift of coherent pulse sequence waveform, a new estimation of multi-targets＇ 2-Dimentional （2-D） DOA angle, Doppler frequency shift and relative time-delay is proposed. Based on a virtual sensor array constructed by pulse cumulating, the estinaations of azimuth, elevation, Doppler frequency shift and time-delay can be obtained simultaneously, and the least number of pulses could be two. This method is computationally efficient even in heavier noised environment, and all estimations are automatically paired in calculation process with no used to any plane sensor array and deal with many spectrum searching. Further more, this algorithm can be targets at the same time only by few sensors. The targets number that can deal with simultaneously is several times to the sensor number, which is the upper limit for normal algorithms such as ESPRIT and MUSIC. These characteristics would be very useful, especially, for aerial systems. Simulations demonstrate the capabilities of this method efficiently.展开更多
Objective Elevated depressive symptoms are well-documented among geriatric adults with cardiovascular disease(CVD);however,few studies have accounted for long-term cumulative depressive symptom exposure.This study det...Objective Elevated depressive symptoms are well-documented among geriatric adults with cardiovascular disease(CVD);however,few studies have accounted for long-term cumulative depressive symptom exposure.This study determined the relationship between cumulative depressive symptoms and CVD.Methods Individual participant data were obtained from the China Health and Retirement Longitudinal Study(CHARLS)and Health and Retirement Study(HRS).Eligible participants had access to assessment information on depressive symptoms and had no history of CVD at baseline.Long-term cumulative depressive symptoms were estimated by calculating the area under the curve based on the Center for Epidemiological Studies Depression Scale.Results Herein,8,861 participants from CHARLS(mean age:58.58 years;male:48.6%)and 7,284 from HRS(60.94 years;35.0%)were enrolled.The median follow-up period was 5 years for the CHARLS and10 years for the HRS.Compared with the first quartile of cumulative depressive symptoms,the HRs(95%CI)in the fourth quartile were 1.73(1.48,2.02)for predicting CVD(P<0.001),1.83(1.52,2.19)for heart disease(P<0.001),1.53(95%CI:1.17,1.99)for stroke(P=0.002)in CHARLS.For HRS,the HRs(95%CI)were 1.41(95%CI:1.27,1.57;P<0.001),1.42(95%CI:1.26,1.59;P<0.001),and 1.30(95%CI:1.06,1.58;P=0.010)respectively.Strong dose-response relationships were observed,with similar results for the two cohorts.Conclusion Long-term cumulative depressive symptoms were significantly associated with incident CVD in middle-aged and older adults,providing insights into controlling long-term depressive symptoms to improve this cohort's health.展开更多
Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical...Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical properties and damage mechanisms of carbonaceous slate under cyclic impact loads of varying intensities,cyclic dynamic tests are conducted using a triaxial split Hopkinson pressure bar.This study analyzes the stress-strain relationship,energy damage evolution,and macro-to-micro failure characteristics.The results show that peak stress and strain are significantly influenced by impact intensity and the number of impacts.The initial dynamic stress is positively correlated with the impact intensity,but with more impact,the dynamic stress decreases while the peak strain increases.Energy evolution follows a pattern of"slow growthfluctuating growthrapid growth,"with the crack initiation stress and its proportion decreasing.CT and SEM analyses reveal that as the impact intensity increases,failure becomes more chaotic,the fracture volume increases,and the fracture mode shifts from interlayer and intergranular to through-layer and trans-granular fractures.These findings provide an experimental basis for soft rock tunnel stability analysis.展开更多
Research on neutron-induced fission product yields of^(232)Th is crucial for understanding the competition between symmetric and asymmetric fission in actinide nuclei.However,obtaining complete isotopic yield distribu...Research on neutron-induced fission product yields of^(232)Th is crucial for understanding the competition between symmetric and asymmetric fission in actinide nuclei.However,obtaining complete isotopic yield distributions over a wide range of neutron energies remains a challenge.In this study,a Bayesian neural network model was developed to predict the independent(IND)and cumulative fission yields of^(232)Th under neutron irradiation at various incident energies.To address the limited availability of experimental data for the analysis of IND mass distributions,we substituted mass-number-based yields with the yields of specific isotopes.Furthermore,physical phenomena or quantities,such as the odd-even effect and isospin,were introduced as constraints to enhance the physical consistency of the predictions.The impact of these constraints was evaluated using mass-chain yield distributions and their dependence on energy.Incorporating physical constraints significantly improves the prediction accuracy,yielding more reliable and physically meaningful fission yield data for nuclear physics and reactor design applications.展开更多
This study developed a modeling methodology for statistical optimization-based geologic hazard susceptibility assessment,aiming to enhance the comprehensive performance and classification accuracy of the assessment mo...This study developed a modeling methodology for statistical optimization-based geologic hazard susceptibility assessment,aiming to enhance the comprehensive performance and classification accuracy of the assessment models.First,the cumulative probability method revealed that a low probability(15%)of geologic hazards between any two geologic hazard points occurred outside a buffer zone with a radius of 2297 m(i.e.,the distance threshold).The training dataset was established,consisting of negative samples(non-hazard points)randomly generated based on the distance threshold,positive samples(i.e.,historical hazards),and 13 conditioning factors.Then,models were built using five machine learning algorithms,namely random forest(RF),gradient boosting decision tree(GBDT),naive Bayes(NB),logistic regression(LR),and support vector machine(SVM).The comprehensive performance of the models was assessed using the area under the receiver operating characteristic curve(AUC)and overall accuracy(OA)as indicators,revealing that RF exhibited the best performance,with OA and AUC values of 2.7127 and 0.981,respectively.Furthermore,the machine learning models constructed by considering the distance threshold outperformed those built using the unoptimized dataset.The characteristic factors were ranked using the mutual information method,with their scores decreasing in the order of rainfall(0.1616),altitude(0.06),normalized difference vegetation index(NDVI;0.04),and distance from roads(0.03).Finally,the geologic hazard susceptibility classification was assessed using the natural breaks method combined with a clustering algorithm.The results indicate that the clustering algorithm exhibited higher classification accuracy than the natural breaks method.The findings of this study demonstrate that the proposed model optimization scheme can provide a scientific basis for the prevention and control of geologic hazards.展开更多
BACKGROUND Sensitivity to stress is essential in the onset,clinical symptoms,course,and prognosis of major depressive disorder(MDD).Meanwhile,it was unclear how variously classified but connected stress-sensitivity va...BACKGROUND Sensitivity to stress is essential in the onset,clinical symptoms,course,and prognosis of major depressive disorder(MDD).Meanwhile,it was unclear how variously classified but connected stress-sensitivity variables affect MDD.We hypothesize that high-level trait-and state-related stress-sensitivity factors may have different cumulative effects on the clinical symptoms and follow-up outcomes of MDD.AIM To investigate how stress-sensitivity factors added up and affected MDD clinical symptoms and follow-up results.METHODS In this prospective study,281 MDD patients were enrolled from a tertiary care setting.High-level stress-sensitivity factors were classified as trait anxiety,state anxiety,perceived stress,and neuroticism,with a total score in the top quartile of the research cohort.The cumulative effects of stress-sensitivity factors on cognitive dysfunction,disability and functional impairment,suicide risk,and depressive and anxiety symptoms were examined using an analysis of variance with linear trend analysis.Correlations were investigated further using multiple regression analysis.RESULTS Regarding high-level stress-sensitivity factors,53.40%of patients had at least one at baseline,and 29.61%had two or more.Four high-level stress-sensitivity components had significant cumulative impacts on MDD symptoms at baseline(all P<0.001).Perceived stress predicted the greatest effect sizes of state-related factors on depressive symptoms(partialη^(2)=0.153;standardizedβ=0.195;P<0.05).The follow-up outcomes were significantly impacted only by the high-level trait-related components,mainly when it came to depressive symptoms and suicide risk,which were predicted by trait anxiety and neuroticism,respectively(partialη^(2)=0.204 and 0.156;standardizedβ=0.247 and 0.392;P<0.05).CONCLUSION To enhance outcomes of MDD and lower the suicide risk,screening for stress-sensitivity factors and considering multifaceted measures,mainly focusing on trait-related ones,should be addressed clinically.展开更多
A typical Whipple shield consists of double-layered plates with a certain gap.The space debris impacts the outer plate and is broken into a debris cloud(shattered,molten,vaporized)with dispersed energy and momentum,wh...A typical Whipple shield consists of double-layered plates with a certain gap.The space debris impacts the outer plate and is broken into a debris cloud(shattered,molten,vaporized)with dispersed energy and momentum,which reduces the risk of penetrating the bulkhead.In the realm of hypervelocity impact,strain rate(>10^(5)s^(-1))effects are negligible,and fluid dynamics is employed to describe the impact process.Efficient numerical tools for precisely predicting the damage degree can greatly accelerate the design and optimization of advanced protective structures.Current hypervelocity impact research primarily focuses on the interaction between projectile and front plate and the movement of debris cloud.However,the damage mechanism of debris cloud impacts on rear plates-the critical threat component-remains underexplored owing to complex multi-physics processes and prohibitive computational costs.Existing approaches,ranging from semi-empirical equations to a machine learningbased ballistic limit prediction method,are constrained to binary penetration classification.Alternatively,the uneven data from experiments and simulations caused these methods to be ineffective when the projectile has irregular shapes and complicate flight attitude.Therefore,it is urgent to develop a new damage prediction method for predicting the rear plate damage,which can help to gain a deeper understanding of the damage mechanism.In this study,a machine learning(ML)method is developed to predict the damage distribution in the rear plate.Based on the unit velocity space,the discretized information of debris cloud and rear plate damage from rare simulation cases is used as input data for training the ML models,while the generalization ability for damage distribution prediction is tested by other simulation cases with different attack angles.The results demonstrate that the training and prediction accuracies using the Random Forest(RF)algorithm significantly surpass those using Artificial Neural Networks(ANNs)and Support Vector Machine(SVM).The RF-based model effectively identifies damage features in sparsely distributed debris cloud and cumulative effect.This study establishes an expandable new dataset that accommodates additional parameters to improve the prediction accuracy.Results demonstrate the model's ability to overcome data imbalance limitations through debris cloud features,enabling rapid and accurate rear plate damage prediction across wider scenarios with minimal data requirements.展开更多
Monte Carlo(MC) simulations have been performed to refine the estimation of the correction-toscaling exponent ω in the 2D φ^(4)model,which belongs to one of the most fundamental universality classes.If corrections h...Monte Carlo(MC) simulations have been performed to refine the estimation of the correction-toscaling exponent ω in the 2D φ^(4)model,which belongs to one of the most fundamental universality classes.If corrections have the form ∝ L^(-ω),then we find ω=1.546(30) andω=1.509(14) as the best estimates.These are obtained from the finite-size scaling of the susceptibility data in the range of linear lattice sizes L ∈[128,2048] at the critical value of the Binder cumulant and from the scaling of the corresponding pseudocritical couplings within L∈[64,2048].These values agree with several other MC estimates at the assumption of the power-law corrections and are comparable with the known results of the ε-expansion.In addition,we have tested the consistency with the scaling corrections of the form ∝ L^(-4/3),∝L^(-4/3)In L and ∝L^(-4/3)/ln L,which might be expected from some considerations of the renormalization group and Coulomb gas model.The latter option is consistent with our MC data.Our MC results served as a basis for a critical reconsideration of some earlier theoretical conjectures and scaling assumptions.In particular,we have corrected and refined our previous analysis by grouping Feynman diagrams.The renewed analysis gives ω≈4-d-2η as some approximation for spatial dimensions d <4,or ω≈1.5 in two dimensions.展开更多
Using cumulative quantum mechanics(CQM)and the method of generalized mathematical transfer(MGMT),we analytically study quantum nanometer cumulative-dissipative structures(CDS)and the forces arising within them,which f...Using cumulative quantum mechanics(CQM)and the method of generalized mathematical transfer(MGMT),we analytically study quantum nanometer cumulative-dissipative structures(CDS)and the forces arising within them,which focus nanostructures into regular,fractalized systems—cumulative-dissipative standing hydrogen-like excitons(atoms,molecules,lines,surfaces)and flickering crystals we discovered for the first time.(1)We demonstrate the formation of Vysikaylo standing excitons on permittivity[ε(r)]inhomogeneities in diamond in the nanoscale regions of foreign atoms.(2)For the first time,we solve the problem of measuringε(r)profiles in inhomogeneous nanoscale structures using Raman spectra(RS)[with an accuracy of up to 99.9%forε(r)and a step of up to 0.3 nm depending on the distance from the impurity atom(boron)].(3)Using our theory of Vysikaylo standing excitons,we explain the experimental observation of the degeneracy of electron spectra in standing excitons with respect to the principal quantum number n and n−1/2.By comparing the theory and experimental observations of RS in diamonds doped with boron,we solve the problem(that we formulated previously)between the de Broglie hypothesis and the classical new quantum mechanics of Dirac(which limits the-functions,or prohibits symmetric de Broglie half-waves in spherically and cylindrically symmetric quantum resonators)in favor of the de Broglie hypothesis.Based on the works of Wannier and Mott,we refine the definition of the permittivity of nanocrystals as a coefficient in electric potentials[U(r)→ε(r)U(r)]rather than electric fields[D(r)=ε(r)E(r)].We construct the most complete theory of the chemical doping of crystals(using the example of group IV crystals doped with group III and V atoms).For the first time,we raise the question of the quantum cleaning of crystals or the accumulation of dopant atoms.展开更多
Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves a...Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.展开更多
BACKGROUND Complications arising from the polyps in Peutz-Jeghers syndrome(PJS)have historically been addressed through surgical treatment.Enteroscopic poly-pectomy is hypothesized to reduce the risk of surgery in PJS...BACKGROUND Complications arising from the polyps in Peutz-Jeghers syndrome(PJS)have historically been addressed through surgical treatment.Enteroscopic poly-pectomy is hypothesized to reduce the risk of surgery in PJS.However,the optimal timing for polyp screening and preventive intervention using entero-scopic polypectomy remains uncertain.This is primarily due to the extremely low incidence of the condition and the paucity of data regarding the natural risk of requiring surgery and its age distribution in PJS patients.In order to develop recommendations on the appropriate timing of polyp screening and preventive intervention in PJS,a comprehensive understanding of the natural surgical risks AIM To investigate the natural surgical risks associated with polyps in PJS and to clarify their age distribution.METHODS A web-based open survey was launched to collect information from Chinese individuals suspected of having PJS.The questionnaire was distributed to the PJS instant messaging groups using a quick response code method.The data were analyzed using descriptive statistical methods,and the cumulative incidence of surgery was calculated using the Kaplan-Meier method.RESULTS Of the 442 patients enrolled,301(68.10%)had undergone 506 surgical procedures prior to enteroscopy or the survey deadline.Among the 506 surgical procedures,388(76.68%)were performed on patients aged between 6 and 25 years.The cumulative incidence rates of the first surgical procedure at 5,10,15,20,25,and 30 years of age were 5.0%(95%confidence interval[CI]:2.9%-7.0%),20.6%(95%CI:16.6%-24.4%),40.5%(95%CI:35.5%-45.1%),58.0%(95%CI:52.7%-62.7%),72.6%(95%CI:67.3%-77.0%),and 82.4%(95%CI:77.0%-86.5%),respectively.The primary indications for the first surgical procedures were intussusception(81.40%),obstruction(13.95%),and gas-trointestinal bleeding(4.65%).The cumulative incidence rates of requiring a second surgical procedure within 1,3,5,10 and 15 years following the first surgical procedure were 3.7%(95%CI:1.5%-5.8%),12.5%(95%CI:8.6%-16.2%),20.3%(95%CI:15.6%-24.8%),37.0%(95%CI:33.1%-45.3%),54.2%(95%CI:46.8%-60.5%),respectively.Patients who underwent their first surgical procedure at the age of nine years or younger presented an elevated risk of requiring a second surgical procedure(P<0.01).CONCLUSION Chinese patients with PJS have a high natural risk of undergoing surgery.Without preventive intervention,these procedures may become necessary at an early age and may be repeated.Early screening and regular surveillance,with preventive intervention if necessary,should commence at six years of age.展开更多
Background:Trunk lean angle is an underrepre sented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries.The purp...Background:Trunk lean angle is an underrepre sented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries.The purpose of this study was to systematically alter the trunk lean angle in distance running using an auditory real-time feedback approach and to derive dose-response relationships between sagittal plane trunk lean angle and lower extremity(cumulative)joint loading to guide overuse load management in clinical practice.Methods:Thirty recreational runners(15 males and 15 females)ran at a constant speed of 2.5 m/s at 5 systematically varied trunk lean conditions on a force-instrumented treadmill while kinematic and kinetic data were captured.Results:A change in trunk lean angle from-2°(extension)to 28°(flexion)resulted in a systematic increase in stance phase angular impulse,cumulative impulse,and peak moment at the hip joint in the sagittal and transversal plane.In contrast,a systematic decrease in these parameters at the knee j oint in the sagittal plane and the hip joint in the frontal plane was found(p<0.001).Linear fitting revealed that with every degree of anterior trunk leaning,the cumulative hip joint extension loading increases by 3.26 Nm·s/kg/1000 m,while simultaneously decreasing knee joint extension loading by 1.08 Nm·s/kg/1000 m.Conclusion:Trunk leaning can reduce knee joint loading and hip joint abduction loading,at the cost of hip joint loading in the sagittal and transversal planes during distance running.Modulating lower extremity joint loading by altering trunk lean angle is an effective strategy to redistribute joint load between/within the knee and hip joints.When implementing anterior trunk leaning in clinical practice,the increased demands on the hip musculature,dynamic stability,and the potential trade-off with running economy should be considered.展开更多
As the proportion of newenergy increases,the traditional cumulant method(CM)produces significant errorswhen performing probabilistic load flow(PLF)calculations with large-scale wind power integrated.Considering the wi...As the proportion of newenergy increases,the traditional cumulant method(CM)produces significant errorswhen performing probabilistic load flow(PLF)calculations with large-scale wind power integrated.Considering the wind speed correlation,a multi-scenario PLF calculation method that combines random sampling and segmented discrete wind farm power was proposed.Firstly,based on constructing discrete scenes of wind farms,the Nataf transform is used to handle the correlation between wind speeds.Then,the random sampling method determines the output probability of discrete wind power scenarios when wind speed exhibits correlation.Finally,the PLF calculation results of each scenario areweighted and superimposed following the total probability formula to obtain the final power flow calculation result.Verified in the IEEE standard node system,the absolute percent error(APE)for the mean and standard deviation(SD)of the node voltages and branch active power are all within 1%,and the average root mean square(AMSR)values of the probability curves are all less than 1%.展开更多
Objective:This study aimed to investigate the longitudinal trajectories of cumulative fluid balance(CFB)in intensive care unit(ICU)patients and analyze the relationship between different trajectory groups and the occu...Objective:This study aimed to investigate the longitudinal trajectories of cumulative fluid balance(CFB)in intensive care unit(ICU)patients and analyze the relationship between different trajectory groups and the occurrence of pressure injuries(PIs).Methods:In this retrospective longitudinal study,we obtained health-related data from the Medical Information Mart for Intensive Care IV database,including sociodemographic,disease-related variables,and ICU treatment variables.The daily CFB adjusted for body weight was calculated,and the occurrence of PIs during the ICU stay was recorded.A group-based trajectory model was used to explore the different CFB trajectories.Binary logistic regression was used to analyze the relationship between the CFB trajectory group and PIs.Results:Among the 4,294 included participants,we identified four distinct trajectories of CFB in ICU patients:the rapid accumulation group(12.5%),the slow accumulation group(28.5%),the neutral balance group(41.7%),and the negative decrease group(17.3%).After adjusting for some sociodemographic,disease-related variables,and ICU treatment variables,the rapid accumulation group had an OR of 1.63(95%CI:1.30,2.04)for all stages of PIs and an OR of 1.36(95%CI:1.08,1.72)for stage II or higher PIs compared to the neutral balance group.Conclusions:Four unique trajectories of CFB were identified among patients in the ICU,including rapid accumulation,slow accumulation,neutral balance,and negative decrease.Rapid accumulation independently increased the risk of PIs during ICU stay.展开更多
In the civil and mining industries,bolts are critical components of support systems,playing a vital role in ensuring their stability.Glass fibre reinforced polymer(GFRP)bolts are widely used because they are corrosion...In the civil and mining industries,bolts are critical components of support systems,playing a vital role in ensuring their stability.Glass fibre reinforced polymer(GFRP)bolts are widely used because they are corrosion-resistant and cost-effective.However,the damage mechanisms of GFRP bolts under blasting dynamic loads are still unclear,especially compared to metal bolts.This study investigates the cumulative damage of fully grouted GFRP bolts under blasting dynamic loads.The maximum axial stress at the tails of the bolts is defined as the damage variable,based on the failure characteristics of GFRP bolts.By combining this with Miner's cumulative damage theory,a comprehensive theoretical and numerical model is established to calculate cumulative damage.Field data collected from the Jinchuan No.3 Mining Area,including GFRP bolts parameters and blasting vibration data are used for further analysis of cumulative damage in fully grouted GFRP bolts.Results indicate that with an increasing number of blasts,axial stress increases in all parts of GFRP bolts.The tail exhibits the most significant rise,with stress extending deeper into the anchorage zone.Cumulative damage follows an exponential trend with the number of blasts,although the incremental damage per blast decelerates over time.Higher dynamic load intensities accelerate damage accumulation,leading to an exponential decline in the maximum loading cycles before failure.Additionally,stronger surrounding rock and grout mitigate damage accumulation,with the effect of surrounding rock strength being more pronounced than that of grout.In contrast,the maximum axial stress of metal bolts increases quickly to a certain point and then stabilizes.This shows a clear difference between GFRP and metal bolts.This study presents a new cumulative damage theory that underpins the design of GFRP bolt support systems under blasting conditions,identifies key damage factors,and suggests mitigation measures to enhance system stability.展开更多
In November 2024,the Global Solar Council announced that the world cumulative solar capacity reached 2 terawatts,twice as much as in mid-2022,clearly showing that solar energy is set to lead the energy transition.
Higher education is transitioning from mass expansion to high-quality development.In this process,mental health issues among college students have become increasingly prominent,encompassing not only academic stress-in...Higher education is transitioning from mass expansion to high-quality development.In this process,mental health issues among college students have become increasingly prominent,encompassing not only academic stress-induced anxiety but also complex challenges such as interpersonal adaptation difficulties and career planning confusion.Traditional“problem-oriented”intervention models have shown limitations in responsiveness and adaptability,often only passively addressing existing psychological crises rather than preventing them in advance.This study aims to explore an AI-powered“positive psychology”proactive intervention model through developing an intelligent system.The system automatically collects,filters,and personalizes recommendations for positive activities on campus.Using a randomized controlled trial design,we conducted an 8-week intervention study involving 126 college students at a university.The study found that AI-based“campus positive activity”recommendations effectively boost students’positive emotions and promote psychological capital development through cumulative micro-interventions.This provides universities with empirical evidence and innovative methods to implement low-cost,efficient,and scalable mental health promotion programs through smart technology.展开更多
On 18 December 2023,a MS 6.2 earthquake struck the Jishishan area in Northwest China,located at the border of the Qinghai-Tibet and Loess Plateau.The earthquake triggered shallow loess landslides,small rock failures,a...On 18 December 2023,a MS 6.2 earthquake struck the Jishishan area in Northwest China,located at the border of the Qinghai-Tibet and Loess Plateau.The earthquake triggered shallow loess landslides,small rock failures,and soil cracks,mainly along hilly gullies and cut slopes at the edges of terraced fields.A rare large-scale flowslide also occurred in irrigated farmland.These seismic landslides and collapses blocked roads,buried farmland,damaged houses,and resulted in many casualties.Field investigations revealed that these geological hazards were concentrated around cultivated land.Consequently,cultivated land was introduced as an engineering geological zoning factor into the seismic geological hazard risk assessment for Jishishan area.The Newmark cumulative displacement model was refined by incorporating lithological uncertainties via the Monte Carlo method.Comparative analysis of coseismic geohazards with and without considering cultivated land suggests that,in loess-covered areas with cultivation activities,the consideration of the disturbed characteristics of soils provides a more accurate probabilistic risk assessment of seismic geohazards.Human cultivation and irrigation activities affect the physical properties of surface soil,the terraced fields around earthquake prone areas have a risk of earthquake-induced geological hazards.This study may offer valuable insights for hazard prevention and mitigation in high fortification intensity loess covered areas.展开更多
One of the primary tasks of earthquake early warning(EEW)systems is to predict potential earthquake damage rapidly and accurately.Cumulative absolute velocity(CAV),Arias intensity(I_(A)),and spectrum intensity(SI)are ...One of the primary tasks of earthquake early warning(EEW)systems is to predict potential earthquake damage rapidly and accurately.Cumulative absolute velocity(CAV),Arias intensity(I_(A)),and spectrum intensity(SI)are important parameters for measuring ground motion intensity and assessing earthquake damage.Due to the limited available information in EEW,CAV,I_(A),and SI cannot be accurately predicted using traditional EEW methods.In this paper,we propose an end-to-end deep learning-based Ground motion Intensity prediction Network(ENGINet)for on-site EEW.The aim of the ENGINet is to predict CAV,I_(A),and SI rapidly and reliably.ENGINet is based on a convolutional neural network and recurrent neural network.The inputs of the network are three-component acceleration records,three-component velocity records,and three-component displacement records obtained by a single station.The results from the test dataset show that at 3 s after the P-wave arrival,compared with the baseline models and other traditional methods,ENGINet has better performance in predicting CAV,I_(A),and SI.Our results indicate that ENGINet can quickly and accurately predict CAV,I_(A),and SI to some extent and has good potential in EEW efforts.展开更多
Enhancing the spatio-temporal connectivity of dynamic landscapes is crucial for species to adapt to climate change.However,the spatio-temporal connectivity network approach considering climate change and species movem...Enhancing the spatio-temporal connectivity of dynamic landscapes is crucial for species to adapt to climate change.However,the spatio-temporal connectivity network approach considering climate change and species movement is often overlooked.Taking Tibetan wild ass on the Qinghai-Xizang Plateau as an example,we simulated species distribution under current(2019)and future scenarios(2100),constructed spatio-temporal connectivity networks,and assessed the spatio-temporal connectivity.The results show that under the current,SSP2–4.5 and SSP3–7.0 scenarios,suitable habitats for the Tibetan wild ass account for 21.11%,21.34%,and 20.95%of the total area,respectively,with increased fragmentation projected by 2100.78.35%of the habitats which are predicted to be suitable under current conditions will remain suitable in the future,which can be regarded as stable climate refuges.With the increase in future emission intensity,the percentage of auxiliary connectivity corridors increases from 27.65%to 33.57%.This indicates that more patches will function as temporary refuges and the auxiliary connectivity corridors will gradually weaken the dominance of direct connectivity corridors.Under different SSP-RCP scenarios,the internal spatio-temporal connectivity is always higher than direct connectivity and auxiliary connectivity,accounting for 42%–43%.Compared with the spatio-temporal perspective,the purely spatial perspective overestimates network connectivity by about 28%considering all current and future patches,and underestimates network connectivity by 16%–21%when only considering all current or future patches.In this study,a new approach of spatio-temporal connectivity network is proposed to bridge climate refuges,which contributes to the long-term effectiveness of conservation networks for species’adaptation to climate change.展开更多
基金Supported by the NWPU Graduate Innovation Lab Cen-ter of China (No.04029)
文摘The Directions of Arrivals （DOAs）, speeds and distances of targets are all required for array signal processing. Based on the periodic phase shift of coherent pulse sequence waveform, a new estimation of multi-targets＇ 2-Dimentional （2-D） DOA angle, Doppler frequency shift and relative time-delay is proposed. Based on a virtual sensor array constructed by pulse cumulating, the estinaations of azimuth, elevation, Doppler frequency shift and time-delay can be obtained simultaneously, and the least number of pulses could be two. This method is computationally efficient even in heavier noised environment, and all estimations are automatically paired in calculation process with no used to any plane sensor array and deal with many spectrum searching. Further more, this algorithm can be targets at the same time only by few sensors. The targets number that can deal with simultaneously is several times to the sensor number, which is the upper limit for normal algorithms such as ESPRIT and MUSIC. These characteristics would be very useful, especially, for aerial systems. Simulations demonstrate the capabilities of this method efficiently.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(2021A1515011629)Construction of High-level University of Guangdong(G623330580and G621331128)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2019)。
文摘Objective Elevated depressive symptoms are well-documented among geriatric adults with cardiovascular disease(CVD);however,few studies have accounted for long-term cumulative depressive symptom exposure.This study determined the relationship between cumulative depressive symptoms and CVD.Methods Individual participant data were obtained from the China Health and Retirement Longitudinal Study(CHARLS)and Health and Retirement Study(HRS).Eligible participants had access to assessment information on depressive symptoms and had no history of CVD at baseline.Long-term cumulative depressive symptoms were estimated by calculating the area under the curve based on the Center for Epidemiological Studies Depression Scale.Results Herein,8,861 participants from CHARLS(mean age:58.58 years;male:48.6%)and 7,284 from HRS(60.94 years;35.0%)were enrolled.The median follow-up period was 5 years for the CHARLS and10 years for the HRS.Compared with the first quartile of cumulative depressive symptoms,the HRs(95%CI)in the fourth quartile were 1.73(1.48,2.02)for predicting CVD(P<0.001),1.83(1.52,2.19)for heart disease(P<0.001),1.53(95%CI:1.17,1.99)for stroke(P=0.002)in CHARLS.For HRS,the HRs(95%CI)were 1.41(95%CI:1.27,1.57;P<0.001),1.42(95%CI:1.26,1.59;P<0.001),and 1.30(95%CI:1.06,1.58;P=0.010)respectively.Strong dose-response relationships were observed,with similar results for the two cohorts.Conclusion Long-term cumulative depressive symptoms were significantly associated with incident CVD in middle-aged and older adults,providing insights into controlling long-term depressive symptoms to improve this cohort's health.
基金support from the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A2060)the National Natural Science Foundation of China(Grant Nos.42177143 and 52474150).
文摘Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical properties and damage mechanisms of carbonaceous slate under cyclic impact loads of varying intensities,cyclic dynamic tests are conducted using a triaxial split Hopkinson pressure bar.This study analyzes the stress-strain relationship,energy damage evolution,and macro-to-micro failure characteristics.The results show that peak stress and strain are significantly influenced by impact intensity and the number of impacts.The initial dynamic stress is positively correlated with the impact intensity,but with more impact,the dynamic stress decreases while the peak strain increases.Energy evolution follows a pattern of"slow growthfluctuating growthrapid growth,"with the crack initiation stress and its proportion decreasing.CT and SEM analyses reveal that as the impact intensity increases,failure becomes more chaotic,the fracture volume increases,and the fracture mode shifts from interlayer and intergranular to through-layer and trans-granular fractures.These findings provide an experimental basis for soft rock tunnel stability analysis.
基金supported by the National Natural Science Foundation of China(Nos.12247126 and 12375123)Henan Postdoctoral Foundation(No.HN2024013)the Natural Science Foundation of Henan Province(No.242300421048)。
文摘Research on neutron-induced fission product yields of^(232)Th is crucial for understanding the competition between symmetric and asymmetric fission in actinide nuclei.However,obtaining complete isotopic yield distributions over a wide range of neutron energies remains a challenge.In this study,a Bayesian neural network model was developed to predict the independent(IND)and cumulative fission yields of^(232)Th under neutron irradiation at various incident energies.To address the limited availability of experimental data for the analysis of IND mass distributions,we substituted mass-number-based yields with the yields of specific isotopes.Furthermore,physical phenomena or quantities,such as the odd-even effect and isospin,were introduced as constraints to enhance the physical consistency of the predictions.The impact of these constraints was evaluated using mass-chain yield distributions and their dependence on energy.Incorporating physical constraints significantly improves the prediction accuracy,yielding more reliable and physically meaningful fission yield data for nuclear physics and reactor design applications.
基金supported by a project entitled Loess Plateau Region-Watershed-Slope Geological Hazard Multi-Scale Collaborative Intelligent Early Warning System of the National Key R&D Program of China(2022YFC3003404)a project of the Shaanxi Youth Science and Technology Star(2021KJXX-87)public welfare geological survey projects of Shaanxi Institute of Geologic Survey(20180301,201918,202103,and 202413)。
文摘This study developed a modeling methodology for statistical optimization-based geologic hazard susceptibility assessment,aiming to enhance the comprehensive performance and classification accuracy of the assessment models.First,the cumulative probability method revealed that a low probability(15%)of geologic hazards between any two geologic hazard points occurred outside a buffer zone with a radius of 2297 m(i.e.,the distance threshold).The training dataset was established,consisting of negative samples(non-hazard points)randomly generated based on the distance threshold,positive samples(i.e.,historical hazards),and 13 conditioning factors.Then,models were built using five machine learning algorithms,namely random forest(RF),gradient boosting decision tree(GBDT),naive Bayes(NB),logistic regression(LR),and support vector machine(SVM).The comprehensive performance of the models was assessed using the area under the receiver operating characteristic curve(AUC)and overall accuracy(OA)as indicators,revealing that RF exhibited the best performance,with OA and AUC values of 2.7127 and 0.981,respectively.Furthermore,the machine learning models constructed by considering the distance threshold outperformed those built using the unoptimized dataset.The characteristic factors were ranked using the mutual information method,with their scores decreasing in the order of rainfall(0.1616),altitude(0.06),normalized difference vegetation index(NDVI;0.04),and distance from roads(0.03).Finally,the geologic hazard susceptibility classification was assessed using the natural breaks method combined with a clustering algorithm.The results indicate that the clustering algorithm exhibited higher classification accuracy than the natural breaks method.The findings of this study demonstrate that the proposed model optimization scheme can provide a scientific basis for the prevention and control of geologic hazards.
基金Supported by Science and Technology Innovation 2030-Major Projects,No.2021ZD0202000National Key Research and Development Program of China,No.2019YFA0706200+2 种基金National Natural Science Foundation of China,No.82371535Science and Technology Innovation Program of Hunan Province,No.2023RC3083Fundamental Research Funds for the Central Universities of Central South University,No.2023ZZTS0838.
文摘BACKGROUND Sensitivity to stress is essential in the onset,clinical symptoms,course,and prognosis of major depressive disorder(MDD).Meanwhile,it was unclear how variously classified but connected stress-sensitivity variables affect MDD.We hypothesize that high-level trait-and state-related stress-sensitivity factors may have different cumulative effects on the clinical symptoms and follow-up outcomes of MDD.AIM To investigate how stress-sensitivity factors added up and affected MDD clinical symptoms and follow-up results.METHODS In this prospective study,281 MDD patients were enrolled from a tertiary care setting.High-level stress-sensitivity factors were classified as trait anxiety,state anxiety,perceived stress,and neuroticism,with a total score in the top quartile of the research cohort.The cumulative effects of stress-sensitivity factors on cognitive dysfunction,disability and functional impairment,suicide risk,and depressive and anxiety symptoms were examined using an analysis of variance with linear trend analysis.Correlations were investigated further using multiple regression analysis.RESULTS Regarding high-level stress-sensitivity factors,53.40%of patients had at least one at baseline,and 29.61%had two or more.Four high-level stress-sensitivity components had significant cumulative impacts on MDD symptoms at baseline(all P<0.001).Perceived stress predicted the greatest effect sizes of state-related factors on depressive symptoms(partialη^(2)=0.153;standardizedβ=0.195;P<0.05).The follow-up outcomes were significantly impacted only by the high-level trait-related components,mainly when it came to depressive symptoms and suicide risk,which were predicted by trait anxiety and neuroticism,respectively(partialη^(2)=0.204 and 0.156;standardizedβ=0.247 and 0.392;P<0.05).CONCLUSION To enhance outcomes of MDD and lower the suicide risk,screening for stress-sensitivity factors and considering multifaceted measures,mainly focusing on trait-related ones,should be addressed clinically.
基金supported by National Natural Science Foundation of China(Grant No.12432018,12372346)the Innovative Research Groups of the National Natural Science Foundation of China(Grant No.12221002).
文摘A typical Whipple shield consists of double-layered plates with a certain gap.The space debris impacts the outer plate and is broken into a debris cloud(shattered,molten,vaporized)with dispersed energy and momentum,which reduces the risk of penetrating the bulkhead.In the realm of hypervelocity impact,strain rate(>10^(5)s^(-1))effects are negligible,and fluid dynamics is employed to describe the impact process.Efficient numerical tools for precisely predicting the damage degree can greatly accelerate the design and optimization of advanced protective structures.Current hypervelocity impact research primarily focuses on the interaction between projectile and front plate and the movement of debris cloud.However,the damage mechanism of debris cloud impacts on rear plates-the critical threat component-remains underexplored owing to complex multi-physics processes and prohibitive computational costs.Existing approaches,ranging from semi-empirical equations to a machine learningbased ballistic limit prediction method,are constrained to binary penetration classification.Alternatively,the uneven data from experiments and simulations caused these methods to be ineffective when the projectile has irregular shapes and complicate flight attitude.Therefore,it is urgent to develop a new damage prediction method for predicting the rear plate damage,which can help to gain a deeper understanding of the damage mechanism.In this study,a machine learning(ML)method is developed to predict the damage distribution in the rear plate.Based on the unit velocity space,the discretized information of debris cloud and rear plate damage from rare simulation cases is used as input data for training the ML models,while the generalization ability for damage distribution prediction is tested by other simulation cases with different attack angles.The results demonstrate that the training and prediction accuracies using the Random Forest(RF)algorithm significantly surpass those using Artificial Neural Networks(ANNs)and Support Vector Machine(SVM).The RF-based model effectively identifies damage features in sparsely distributed debris cloud and cumulative effect.This study establishes an expandable new dataset that accommodates additional parameters to improve the prediction accuracy.Results demonstrate the model's ability to overcome data imbalance limitations through debris cloud features,enabling rapid and accurate rear plate damage prediction across wider scenarios with minimal data requirements.
文摘Monte Carlo(MC) simulations have been performed to refine the estimation of the correction-toscaling exponent ω in the 2D φ^(4)model,which belongs to one of the most fundamental universality classes.If corrections have the form ∝ L^(-ω),then we find ω=1.546(30) andω=1.509(14) as the best estimates.These are obtained from the finite-size scaling of the susceptibility data in the range of linear lattice sizes L ∈[128,2048] at the critical value of the Binder cumulant and from the scaling of the corresponding pseudocritical couplings within L∈[64,2048].These values agree with several other MC estimates at the assumption of the power-law corrections and are comparable with the known results of the ε-expansion.In addition,we have tested the consistency with the scaling corrections of the form ∝ L^(-4/3),∝L^(-4/3)In L and ∝L^(-4/3)/ln L,which might be expected from some considerations of the renormalization group and Coulomb gas model.The latter option is consistent with our MC data.Our MC results served as a basis for a critical reconsideration of some earlier theoretical conjectures and scaling assumptions.In particular,we have corrected and refined our previous analysis by grouping Feynman diagrams.The renewed analysis gives ω≈4-d-2η as some approximation for spatial dimensions d <4,or ω≈1.5 in two dimensions.
文摘Using cumulative quantum mechanics(CQM)and the method of generalized mathematical transfer(MGMT),we analytically study quantum nanometer cumulative-dissipative structures(CDS)and the forces arising within them,which focus nanostructures into regular,fractalized systems—cumulative-dissipative standing hydrogen-like excitons(atoms,molecules,lines,surfaces)and flickering crystals we discovered for the first time.(1)We demonstrate the formation of Vysikaylo standing excitons on permittivity[ε(r)]inhomogeneities in diamond in the nanoscale regions of foreign atoms.(2)For the first time,we solve the problem of measuringε(r)profiles in inhomogeneous nanoscale structures using Raman spectra(RS)[with an accuracy of up to 99.9%forε(r)and a step of up to 0.3 nm depending on the distance from the impurity atom(boron)].(3)Using our theory of Vysikaylo standing excitons,we explain the experimental observation of the degeneracy of electron spectra in standing excitons with respect to the principal quantum number n and n−1/2.By comparing the theory and experimental observations of RS in diamonds doped with boron,we solve the problem(that we formulated previously)between the de Broglie hypothesis and the classical new quantum mechanics of Dirac(which limits the-functions,or prohibits symmetric de Broglie half-waves in spherically and cylindrically symmetric quantum resonators)in favor of the de Broglie hypothesis.Based on the works of Wannier and Mott,we refine the definition of the permittivity of nanocrystals as a coefficient in electric potentials[U(r)→ε(r)U(r)]rather than electric fields[D(r)=ε(r)E(r)].We construct the most complete theory of the chemical doping of crystals(using the example of group IV crystals doped with group III and V atoms).For the first time,we raise the question of the quantum cleaning of crystals or the accumulation of dopant atoms.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102480,52278543 and 51978660)Natural Science Foundation of Jiangsu Province(Grant No.BK20231489)。
文摘Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.
文摘BACKGROUND Complications arising from the polyps in Peutz-Jeghers syndrome(PJS)have historically been addressed through surgical treatment.Enteroscopic poly-pectomy is hypothesized to reduce the risk of surgery in PJS.However,the optimal timing for polyp screening and preventive intervention using entero-scopic polypectomy remains uncertain.This is primarily due to the extremely low incidence of the condition and the paucity of data regarding the natural risk of requiring surgery and its age distribution in PJS patients.In order to develop recommendations on the appropriate timing of polyp screening and preventive intervention in PJS,a comprehensive understanding of the natural surgical risks AIM To investigate the natural surgical risks associated with polyps in PJS and to clarify their age distribution.METHODS A web-based open survey was launched to collect information from Chinese individuals suspected of having PJS.The questionnaire was distributed to the PJS instant messaging groups using a quick response code method.The data were analyzed using descriptive statistical methods,and the cumulative incidence of surgery was calculated using the Kaplan-Meier method.RESULTS Of the 442 patients enrolled,301(68.10%)had undergone 506 surgical procedures prior to enteroscopy or the survey deadline.Among the 506 surgical procedures,388(76.68%)were performed on patients aged between 6 and 25 years.The cumulative incidence rates of the first surgical procedure at 5,10,15,20,25,and 30 years of age were 5.0%(95%confidence interval[CI]:2.9%-7.0%),20.6%(95%CI:16.6%-24.4%),40.5%(95%CI:35.5%-45.1%),58.0%(95%CI:52.7%-62.7%),72.6%(95%CI:67.3%-77.0%),and 82.4%(95%CI:77.0%-86.5%),respectively.The primary indications for the first surgical procedures were intussusception(81.40%),obstruction(13.95%),and gas-trointestinal bleeding(4.65%).The cumulative incidence rates of requiring a second surgical procedure within 1,3,5,10 and 15 years following the first surgical procedure were 3.7%(95%CI:1.5%-5.8%),12.5%(95%CI:8.6%-16.2%),20.3%(95%CI:15.6%-24.8%),37.0%(95%CI:33.1%-45.3%),54.2%(95%CI:46.8%-60.5%),respectively.Patients who underwent their first surgical procedure at the age of nine years or younger presented an elevated risk of requiring a second surgical procedure(P<0.01).CONCLUSION Chinese patients with PJS have a high natural risk of undergoing surgery.Without preventive intervention,these procedures may become necessary at an early age and may be repeated.Early screening and regular surveillance,with preventive intervention if necessary,should commence at six years of age.
文摘Background:Trunk lean angle is an underrepre sented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries.The purpose of this study was to systematically alter the trunk lean angle in distance running using an auditory real-time feedback approach and to derive dose-response relationships between sagittal plane trunk lean angle and lower extremity(cumulative)joint loading to guide overuse load management in clinical practice.Methods:Thirty recreational runners(15 males and 15 females)ran at a constant speed of 2.5 m/s at 5 systematically varied trunk lean conditions on a force-instrumented treadmill while kinematic and kinetic data were captured.Results:A change in trunk lean angle from-2°(extension)to 28°(flexion)resulted in a systematic increase in stance phase angular impulse,cumulative impulse,and peak moment at the hip joint in the sagittal and transversal plane.In contrast,a systematic decrease in these parameters at the knee j oint in the sagittal plane and the hip joint in the frontal plane was found(p<0.001).Linear fitting revealed that with every degree of anterior trunk leaning,the cumulative hip joint extension loading increases by 3.26 Nm·s/kg/1000 m,while simultaneously decreasing knee joint extension loading by 1.08 Nm·s/kg/1000 m.Conclusion:Trunk leaning can reduce knee joint loading and hip joint abduction loading,at the cost of hip joint loading in the sagittal and transversal planes during distance running.Modulating lower extremity joint loading by altering trunk lean angle is an effective strategy to redistribute joint load between/within the knee and hip joints.When implementing anterior trunk leaning in clinical practice,the increased demands on the hip musculature,dynamic stability,and the potential trade-off with running economy should be considered.
基金supported by Basic Science Research Program through the National Natural Science Foundation of China(Grant No.61867003).
文摘As the proportion of newenergy increases,the traditional cumulant method(CM)produces significant errorswhen performing probabilistic load flow(PLF)calculations with large-scale wind power integrated.Considering the wind speed correlation,a multi-scenario PLF calculation method that combines random sampling and segmented discrete wind farm power was proposed.Firstly,based on constructing discrete scenes of wind farms,the Nataf transform is used to handle the correlation between wind speeds.Then,the random sampling method determines the output probability of discrete wind power scenarios when wind speed exhibits correlation.Finally,the PLF calculation results of each scenario areweighted and superimposed following the total probability formula to obtain the final power flow calculation result.Verified in the IEEE standard node system,the absolute percent error(APE)for the mean and standard deviation(SD)of the node voltages and branch active power are all within 1%,and the average root mean square(AMSR)values of the probability curves are all less than 1%.
文摘Objective:This study aimed to investigate the longitudinal trajectories of cumulative fluid balance(CFB)in intensive care unit(ICU)patients and analyze the relationship between different trajectory groups and the occurrence of pressure injuries(PIs).Methods:In this retrospective longitudinal study,we obtained health-related data from the Medical Information Mart for Intensive Care IV database,including sociodemographic,disease-related variables,and ICU treatment variables.The daily CFB adjusted for body weight was calculated,and the occurrence of PIs during the ICU stay was recorded.A group-based trajectory model was used to explore the different CFB trajectories.Binary logistic regression was used to analyze the relationship between the CFB trajectory group and PIs.Results:Among the 4,294 included participants,we identified four distinct trajectories of CFB in ICU patients:the rapid accumulation group(12.5%),the slow accumulation group(28.5%),the neutral balance group(41.7%),and the negative decrease group(17.3%).After adjusting for some sociodemographic,disease-related variables,and ICU treatment variables,the rapid accumulation group had an OR of 1.63(95%CI:1.30,2.04)for all stages of PIs and an OR of 1.36(95%CI:1.08,1.72)for stage II or higher PIs compared to the neutral balance group.Conclusions:Four unique trajectories of CFB were identified among patients in the ICU,including rapid accumulation,slow accumulation,neutral balance,and negative decrease.Rapid accumulation independently increased the risk of PIs during ICU stay.
基金funded by the National Natural Science Foundation of China(No.51974206)the Hubei Province Safety Production Special Fund Science and Technology Project(No.KJZX202007007).
文摘In the civil and mining industries,bolts are critical components of support systems,playing a vital role in ensuring their stability.Glass fibre reinforced polymer(GFRP)bolts are widely used because they are corrosion-resistant and cost-effective.However,the damage mechanisms of GFRP bolts under blasting dynamic loads are still unclear,especially compared to metal bolts.This study investigates the cumulative damage of fully grouted GFRP bolts under blasting dynamic loads.The maximum axial stress at the tails of the bolts is defined as the damage variable,based on the failure characteristics of GFRP bolts.By combining this with Miner's cumulative damage theory,a comprehensive theoretical and numerical model is established to calculate cumulative damage.Field data collected from the Jinchuan No.3 Mining Area,including GFRP bolts parameters and blasting vibration data are used for further analysis of cumulative damage in fully grouted GFRP bolts.Results indicate that with an increasing number of blasts,axial stress increases in all parts of GFRP bolts.The tail exhibits the most significant rise,with stress extending deeper into the anchorage zone.Cumulative damage follows an exponential trend with the number of blasts,although the incremental damage per blast decelerates over time.Higher dynamic load intensities accelerate damage accumulation,leading to an exponential decline in the maximum loading cycles before failure.Additionally,stronger surrounding rock and grout mitigate damage accumulation,with the effect of surrounding rock strength being more pronounced than that of grout.In contrast,the maximum axial stress of metal bolts increases quickly to a certain point and then stabilizes.This shows a clear difference between GFRP and metal bolts.This study presents a new cumulative damage theory that underpins the design of GFRP bolt support systems under blasting conditions,identifies key damage factors,and suggests mitigation measures to enhance system stability.
文摘In November 2024,the Global Solar Council announced that the world cumulative solar capacity reached 2 terawatts,twice as much as in mid-2022,clearly showing that solar energy is set to lead the energy transition.
文摘Higher education is transitioning from mass expansion to high-quality development.In this process,mental health issues among college students have become increasingly prominent,encompassing not only academic stress-induced anxiety but also complex challenges such as interpersonal adaptation difficulties and career planning confusion.Traditional“problem-oriented”intervention models have shown limitations in responsiveness and adaptability,often only passively addressing existing psychological crises rather than preventing them in advance.This study aims to explore an AI-powered“positive psychology”proactive intervention model through developing an intelligent system.The system automatically collects,filters,and personalizes recommendations for positive activities on campus.Using a randomized controlled trial design,we conducted an 8-week intervention study involving 126 college students at a university.The study found that AI-based“campus positive activity”recommendations effectively boost students’positive emotions and promote psychological capital development through cumulative micro-interventions.This provides universities with empirical evidence and innovative methods to implement low-cost,efficient,and scalable mental health promotion programs through smart technology.
基金funded by the Basic Scientific Research Fund,Science and Technology Innovation Base of Lanzhou,Institute of Earthquake Forecasting,China Earthquake Administration(Grants No.2020IESLZ03 and 2015IESLZ05)the National Key R&D program of China(Grant No.2017YFC1500906)
文摘On 18 December 2023,a MS 6.2 earthquake struck the Jishishan area in Northwest China,located at the border of the Qinghai-Tibet and Loess Plateau.The earthquake triggered shallow loess landslides,small rock failures,and soil cracks,mainly along hilly gullies and cut slopes at the edges of terraced fields.A rare large-scale flowslide also occurred in irrigated farmland.These seismic landslides and collapses blocked roads,buried farmland,damaged houses,and resulted in many casualties.Field investigations revealed that these geological hazards were concentrated around cultivated land.Consequently,cultivated land was introduced as an engineering geological zoning factor into the seismic geological hazard risk assessment for Jishishan area.The Newmark cumulative displacement model was refined by incorporating lithological uncertainties via the Monte Carlo method.Comparative analysis of coseismic geohazards with and without considering cultivated land suggests that,in loess-covered areas with cultivation activities,the consideration of the disturbed characteristics of soils provides a more accurate probabilistic risk assessment of seismic geohazards.Human cultivation and irrigation activities affect the physical properties of surface soil,the terraced fields around earthquake prone areas have a risk of earthquake-induced geological hazards.This study may offer valuable insights for hazard prevention and mitigation in high fortification intensity loess covered areas.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2024B08。
文摘One of the primary tasks of earthquake early warning(EEW)systems is to predict potential earthquake damage rapidly and accurately.Cumulative absolute velocity(CAV),Arias intensity(I_(A)),and spectrum intensity(SI)are important parameters for measuring ground motion intensity and assessing earthquake damage.Due to the limited available information in EEW,CAV,I_(A),and SI cannot be accurately predicted using traditional EEW methods.In this paper,we propose an end-to-end deep learning-based Ground motion Intensity prediction Network(ENGINet)for on-site EEW.The aim of the ENGINet is to predict CAV,I_(A),and SI rapidly and reliably.ENGINet is based on a convolutional neural network and recurrent neural network.The inputs of the network are three-component acceleration records,three-component velocity records,and three-component displacement records obtained by a single station.The results from the test dataset show that at 3 s after the P-wave arrival,compared with the baseline models and other traditional methods,ENGINet has better performance in predicting CAV,I_(A),and SI.Our results indicate that ENGINet can quickly and accurately predict CAV,I_(A),and SI to some extent and has good potential in EEW efforts.
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFF1303201).
文摘Enhancing the spatio-temporal connectivity of dynamic landscapes is crucial for species to adapt to climate change.However,the spatio-temporal connectivity network approach considering climate change and species movement is often overlooked.Taking Tibetan wild ass on the Qinghai-Xizang Plateau as an example,we simulated species distribution under current(2019)and future scenarios(2100),constructed spatio-temporal connectivity networks,and assessed the spatio-temporal connectivity.The results show that under the current,SSP2–4.5 and SSP3–7.0 scenarios,suitable habitats for the Tibetan wild ass account for 21.11%,21.34%,and 20.95%of the total area,respectively,with increased fragmentation projected by 2100.78.35%of the habitats which are predicted to be suitable under current conditions will remain suitable in the future,which can be regarded as stable climate refuges.With the increase in future emission intensity,the percentage of auxiliary connectivity corridors increases from 27.65%to 33.57%.This indicates that more patches will function as temporary refuges and the auxiliary connectivity corridors will gradually weaken the dominance of direct connectivity corridors.Under different SSP-RCP scenarios,the internal spatio-temporal connectivity is always higher than direct connectivity and auxiliary connectivity,accounting for 42%–43%.Compared with the spatio-temporal perspective,the purely spatial perspective overestimates network connectivity by about 28%considering all current and future patches,and underestimates network connectivity by 16%–21%when only considering all current or future patches.In this study,a new approach of spatio-temporal connectivity network is proposed to bridge climate refuges,which contributes to the long-term effectiveness of conservation networks for species’adaptation to climate change.
