期刊文献+
共找到275,959篇文章
< 1 2 250 >
每页显示 20 50 100
The Mechanism of Heating Rate on the Secondary Recrystallization Evolution in Grain Oriented Silicon Steel
1
作者 GAO Qian LI Jun +3 位作者 WANG Xianhui CAO Laifu GONG Jian LI Bo 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2025年第1期275-282,共8页
Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the... Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically calculated.The effect of precipitate ripening on the Goss texture and magnetic property was investigated.Data indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate increased.Secondary recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}<227>oriented grains growing abnormally and a magnetic induction intensity of 1.90T.Furthermore,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture.However,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 T.At a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this study.The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties. 展开更多
关键词 high temperature annealing heating rate secondary recrystallization grain oriented silicon steel
在线阅读 下载PDF
High-precision spot centroid positioning of high-frame-rate short-wave infrared images for satellite laser communication
2
作者 FU Peng HE Dao-Gang +1 位作者 LIU Jun WANG Yue-Ming 《红外与毫米波学报》 北大核心 2025年第1期66-77,共12页
The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave... The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation.However,there are strong non-uniformity and blind pixels in the short-wave infrared image,which makes the image distorted and leads to the decrease of spot centroid positioning accuracy.Therefore,the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance.A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two,further model-based localization error simulations are performed,and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector.The experimental results show that the non-uniformity of the corrected image is reduced from 7%to 0.6%,the blind pixels rejection rate reaches 100%,the frame rate can be up to 2000 Hz,and the spot centroid localization accuracy is as high as 0.1 pixel point,which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images. 展开更多
关键词 satellite laser communication spot centroid positioning short-wave infrared high frame rate NONUNIFORMITY
在线阅读 下载PDF
Comparative Effects of Doses of Nauclea latifolia and 17 Alpha Methyltestosterone on Masculinization and Growth Rates of Tilapia Orechromis niloticus Larvae in Senegal
3
作者 Mouhamadou Amadou Ly Fafanding Sane +3 位作者 Robane Faye Baboucar Sane Malick Aliou Sene Cheikh Tidiane Ba 《Open Journal of Applied Sciences》 2025年第1期1-12,共12页
One of the main obstacles to the development of aquaculture in Senegal is the availability of fry and juveniles in sufficient quantities. The objective of our study is to evaluate the effects of treatment with the hor... One of the main obstacles to the development of aquaculture in Senegal is the availability of fry and juveniles in sufficient quantities. The objective of our study is to evaluate the effects of treatment with the hormone 17 alpha methyl testosterone (17-&-MT) and different doses of Nauclea latifolia root powder on the masculinization rates of tilapia Oreochromis niloticus larvae in Senegal. A total of 450 larvae of Oreochromis niloticus, with an average size of 0.012 g, were placed in 15 aquariums, each containing 30 individuals and fed one of the 5 diets in triplicate. These individuals were fed either a diet containing a plant extract at a dose of 180 mg (T180), 200 mg (T200) and 250 mg (T250) per kg of food, or a diet containing 60 mg/kg of the hormone 17-&-MT (TMT), or a diet without either the plant extract or the hormone (T0). Individuals were fed for 30 days with the treatment diets, and then with the industrial feed for the rest of the experiment. At the end of the study, the results of the masculinization rate were: 80.49%, 73.13%, 69.23%, 66.67% and 45.95% for T250;T200, TMT, T180 and T0 respectively. In summary, we can say that the 250 mg/kg dose provides better masculinization, followed by 200mg/kg and then 17 α MT. For the plant, the increase in the percentage of males is dose-dependent. These results also translate into better growth of individuals in this order. However, the relatively lower survival rates observed in batches treated with Nauclea latifolia extract indicate that these treatments could have a deleterious effect on the survival of Oreochromis niloticus larvae. These results suggest the use of N. latifolia extract at a dose of 250 mg/kg feed for better production of male O. niloticus larvae without compromising their growth. 展开更多
关键词 Nauclea latifolia Masculinization rate Growth Performance Oreochromis niloticus
在线阅读 下载PDF
A Reaction-Diffusion SIR Model with Saturated Incidence Rate and Vaccination
4
作者 Shaoyi Geng Xiaolin Lin +1 位作者 Danfeng Pang Guoqing Li 《Journal of Applied Mathematics and Physics》 2025年第2期400-418,共19页
In this paper, we establish an SIR reaction-diffusion infectious disease model with saturated incidence rate and vaccination. Firstly, we prove the uniform boundedness of the solution of this model. Secondly, we estab... In this paper, we establish an SIR reaction-diffusion infectious disease model with saturated incidence rate and vaccination. Firstly, we prove the uniform boundedness of the solution of this model. Secondly, we establish the threshold dynamic behavior of the model based on the basic reproduction number R0, specifically, we prove the globally asymptotic stability of the disease-free equilibrium and the uniform persistence of the model. Thirdly, we show the existence and stability of the endemic equilibrium of the homogeneous system and obtain different cases of positive solution. Fourthly, we investigate the effects of vaccination rate and saturated incidence rate on the basic reproduction number. The results indicate that increasing vaccination rate and saturation rate can effectively control the transmission of the disease. Finally, we conduct numerical simulations to verify the aforementioned conclusions. 展开更多
关键词 Reaction-Diffusion Model Saturated Incidence rate Basic Reproduction Number Threshold Dynamics Asymptotic Profile
在线阅读 下载PDF
Coulomb stressing rate changes and seismicity dynamics associated with slow slip events in south-central Alaska
5
作者 ShanShan Li XingLei Li Bing Xu 《Earth and Planetary Physics》 2025年第2期289-308,共20页
Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter ... Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter SSE, occurring in a similar area, lasted approximately 2 years with M_(w) ~7.2 and an average slip rate of ~91 mm/year. To test whether these SSEs triggered earthquakes near the slow slip area, we calculated the Coulomb stressing rate changes on receiver faults by using two fault geometry definitions: nodal planes of focal mechanism solutions of past earthquakes, and optimally oriented fault planes. Regions in the shallow slab(30–60 km) that experienced a significant increase in the Coulomb stressing rate due to slip by the SSEs showed an increase in seismicity rates during SSE periods. No correlation was found in the volumes that underwent a significant increase in the Coulomb stressing rate during the SSE within the crust and the intermediate slab. We modeled variations in seismicity rates by using a combination of the Coulomb stress transfer model and the framework of rate-and-state friction. Our model indicated that the SSEs increased the Coulomb stress changes on adjacent faults,thereby increasing the seismicity rates even though the ratio of the SSE stressing rate to the background stressing rate was small. Each long-term SSE in Alaska brought the megathrust updip of the SSE areas closer to failure by up to 0.1–0.15 MPa. The volumes of significant Coulomb stress changes caused by the Upper and Lower Cook Inlet SSEs did not overlap. 展开更多
关键词 slow slip events Coulomb stressing rate change seismicity rate change receiver fault rate–state stress transfer model seismogenic zone megathrust failure
在线阅读 下载PDF
The Influence of Visible Light on the Consumption Rate of Expanded Polystyrene by Zophobas morio Larvae
6
作者 Tyler J. Ferenz 《Advances in Entomology》 2025年第1期107-119,共13页
The process of disposing of expanded polystyrene (EPS) is by burning it in municipal incinerators. This process gives off EPS microplastics, which can find their way into water, food, blood, and major organ systems. Z... The process of disposing of expanded polystyrene (EPS) is by burning it in municipal incinerators. This process gives off EPS microplastics, which can find their way into water, food, blood, and major organ systems. Zophobas morio larvae are capable of consuming and breaking down EPS within their digestive tracts by minimizing the spread of microplastics. Studies of the consumption of EPS by Z. morio larvae are typically conducted under white or no visible light treatments. This study tested whether the color of visible light influenced the consumption rate of EPS by Z. morio larvae. If Z. morio larvae consume EPS under visible light, then visible light will influence the amount of EPS consumed. If results suggest that the consumption rate is influenced by visible light colors, then Z. morio larvae could be a solution for recycling EPS. This study’s procedure placed Z. morio larvae into 25 jars under one of six visible light treatments of red, yellow, green, blue, white, and no visible light. Each jar contained a pre-weighed block of EPS and six Z. morio larvae. After two weeks, the Z. morio larvae were removed from the jars, and the difference between each pre-weighed EPS block and the weight of the same partially consumed block was recorded in three trials. The data indicates that green and blue visible light treatments resulted in the greatest amount of EPS consumed by Z. morio larvae while the red and yellow had the least amount of EPS consumed by the Z. morio larvae. In conclusion, results indicate that green and blue visible light, compared to the no visible light treatment, could be used to influence the Z. morio larvae to consume more EPS. Green and blue visible light and Z. morio larvae could make the recycling process of EPS more environmentally friendly when used in households or by local environmental organizations. 展开更多
关键词 Zophobas morio Z. morio Superworm LARVAE Visible Light Expanded Polystyrene EPS STYROFOAM Consumption rate POLLUTION RECYCLING Nanoplastics Microplastics
在线阅读 下载PDF
Glomerular filtration rate and comorbidity factors in elderly hospitalizations
7
作者 Hatice Hamarat 《World Journal of Nephrology》 2025年第1期93-98,共6页
BACKGROUND With an increase in the elderly population,the frequency of hospitalizations in recent years has also risen at a rapid pace.This,in turn,has resulted in poor outcomes and costly treatments.Hospitalization r... BACKGROUND With an increase in the elderly population,the frequency of hospitalizations in recent years has also risen at a rapid pace.This,in turn,has resulted in poor outcomes and costly treatments.Hospitalization rates increase in elderly patients due to a decline in glomerular filtration rate(GFR).AIM To investigate the connection between GFR and comorbidity and reasons for hospitalization in elderly patients.METHODS We analyzed patients aged 75 years and over who were admitted to the internal medicine clinic of a tertiary hospital in Eskisehir.At admission,we calculated GFR values using the Modification of Diet in Renal Disease study formula and classified them into six categories:G1,G2,G3a,G3b,G4,and G5.We analyzed associations with hospitalization diagnoses and comorbidity factors.RESULTS The average age of the patients was 80.8 years(±4.5 years).GFR was 57.287±29.5 mL/kg/1.73 m2 in women and 61.3±31.5 mL/kg/1.73 m2 in men(P=0.106).Most patients were admitted to the hospital at G2 stage(32.8%).The main reasons for hospitalization were anemia(34.4%and 28.6%)and malnutrition(20.9%and 20.8%)in women and men,respectively(P=0.078).The most frequent comor-bidity leading to hospitalization was arterial hypertension(n=168,28%),fo-llowed by diabetes(n=166,27.7%)(P=0.001).CONCLUSION When evaluating geriatric patients,low GFR alone does not provide sufficient information.Patients’comorbid factors should also be taken into account.There is no association between low GFR during hospitalization and hospitalization-Hamarat H.Aging and GFR related diagnoses.Knowing the GFR value before hospitalization will be more informative in such studies. 展开更多
关键词 AGING Glomerular filtration rate HOSPITALIZATION COMORBIDITY Elderly hospitalizations
在线阅读 下载PDF
Pricing Multi-Strike Quanto Call Options on Multiple Assets with Stochastic Volatility, Correlation, and Exchange Rates
8
作者 Boris Ter-Avanesov Gunter Meissner 《Applied Mathematics》 2025年第1期113-142,共30页
Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign cur... Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign currencies each with a different strike price in the payoff function. We carry out a comparative performance analysis of different stochastic volatility (SV), stochastic correlation (SC), and stochastic exchange rate (SER) models to determine the best combination of these models for Monte Carlo (MC) simulation pricing. In addition, we test the performance of all model variants with constant correlation as a benchmark. We find that a combination of GARCH-Jump SV, Weibull SC, and Ornstein Uhlenbeck (OU) SER performs best. In addition, we analyze different discretization schemes and their results. In our simulations, the Milstein scheme yields the best balance between execution times and lower standard deviations of price estimates. Furthermore, we find that incorporating mean reversion into stochastic correlation and stochastic FX rate modeling is beneficial for MC simulation pricing. We improve the accuracy of our simulations by implementing antithetic variates variance reduction. Finally, we derive the correlation risk parameters Cora and Gora in our framework so that correlation hedging of quanto options can be performed. 展开更多
关键词 Quanto Option Multi-Strike Option Stochastic Volatility (SV) Stochastic Correlation (SC) Stochastic Exchange rates (SER) CORA GORA Correlation Risk
在线阅读 下载PDF
Prediction of perioperative complications in colorectal cancer via artificial intelligence analysis of heart rate variability
9
作者 Miao-Miao Ge Li-Wen Wang +6 位作者 Jun Wang Jiang Liu Peng Chen Xin-Xin Liu Gang Wang Guan-Wen Gong Zhi-Wei Jiang 《World Journal of Gastrointestinal Surgery》 2025年第4期290-299,共10页
BACKGROUND Heart rate variability(HRV)represents efferent vagus nerve activity,which is suggested to be related to fundamental mechanisms of tumorigenesis and to be a predictor of prognosis in various cancers.Therefor... BACKGROUND Heart rate variability(HRV)represents efferent vagus nerve activity,which is suggested to be related to fundamental mechanisms of tumorigenesis and to be a predictor of prognosis in various cancers.Therefore,this study hypothesized that HRV monitoring could predict perioperative complication(PC)in colorectal cancer(CRC)patients.AIM To investigate the prognostic value of HRV in hospitalized CRC patients.METHODS The observational studies included 87 patients who underwent CRC surgical procedures under enhanced recovery after surgery programs in a first-class hospital.The HRV parameters were compared between the PC group and the non PC(NPC)group from preoperative day 1 to postoperative day(Pod)3.In addition,inflammatory biomarkers and nutritional indicators were also analyzed.RESULTS The complication rate was 14.9%.HRV was markedly abnormal after surgery,especially in the PC group.The frequency-domain parameters(including pNN50)and time-domain parameters[including high-frequency(HF)]of HRV were significantly different between the two groups postoperatively.The pNN50 was significantly greater at Pod1 in the PC group than that in the NPC group and returned to baseline at Pod2,suggesting that patients with complications exhibited autonomic nerve dysfunction in the early postoperative period.In the PC group,HFs were also enhanced from Pod1 and were significantly higher than in the NPC group;inflammatory biomarkers were significantly elevated at Pod2 and Pod3;the levels of nutritional indicators were significantly lower at Pod1 and Pod2;and the white blood cell count was slightly elevated at Pod3.CONCLUSION HRV is independently associated with postoperative complications in patients with CRC.Abnormal HRV could predicted an increased risk of postoperative complications in CRC patients.Continuous HRV could be used to monitor complications in patients with CRC during the perioperative period. 展开更多
关键词 Colorectal cancer Heart rate variability COMPLICATIONS Perioperative period PREDICTION
在线阅读 下载PDF
Shortage of storage carbohydrates mainly determines seed abscission in Torreya grandis 'Merrillii'
10
作者 Tao Liu Xiaolong Zhao +6 位作者 Guangxia Zhu Caoliang Jin Jingwei Yan Jinwei Suo Weiwu Yu Yuanyuan Hu Jiasheng Wu 《Horticultural Plant Journal》 2025年第2期619-632,共14页
Torreya grandis'Merrillii'is a well-known nut in South China with high nutritional value.Severe premature seed abscission limits the industrial development of T.grandis by causing serious economic losses.Howev... Torreya grandis'Merrillii'is a well-known nut in South China with high nutritional value.Severe premature seed abscission limits the industrial development of T.grandis by causing serious economic losses.However,the physiological mechanisms of seed abscission in T.grandis remain poorly understood.To gain insight into the relationships between carbohydrate status and seed abscission,three-year-old seed-bearing branches were taken as representative materials for the entire tree.Furthermore,the time course of changes in the photosynthetic rate and the non-structural carbohydrate(NSC)dynamics were monitored in the main sources(the one-year-old and two-year-old shoots),and the dry weight and NSC levels of sinks(the seeds,current female cone cluster,and current vegetative cluster)across all seed development stages were recorded.The cumulative seed abscission rate significantly increased,reaching 91.5%from 0 to 72 days after seed protrusion time(SPT).NSC levels in the main sources significantly decreased by 56%-79%,accompanied by a significantly increased photosynthesis rate of 17.1%-49.1%during that period and increased NSC levels in the three sinks.The gene expression level of cell wall invertase(TgCWIN)was significantly correlated with sucrose,fructose,and glucose levels.The carbon storage capacity of the main sources significantly decreased from 6.03 to3.14 mmol C·d^(-1),with a stable photosynthetic capacity,from 0 to 72 days after SPT,whereas the carbon demand of the three sinks showed a continuously increasing trend from 3.14 to 7.71 mmol C·d^(-1).In addition,sucrose supplementation significantly decreased the cumulative seed abscission rate.These results suggest that storage carbohydrates play a major role in the regulatory mechanism of seed abscission in T.grandis.Our study provides a theoretical basis for improving T.grandis yield through establishing a better carbon balance between sources and sinks using timely fertilization or proper pruning procedures. 展开更多
关键词 Storage carbohydrates Seasonal photosynthetic rate Non-structural carbohydrates Seed abscission
在线阅读 下载PDF
On load dependence of detachment rate of kinesin motor
11
作者 Xiao-Xuan Shi Yao Wang +1 位作者 Yu-Ru Liu Ping Xie 《Chinese Physics B》 2025年第1期498-505,共8页
Kinesin is an archetypal microtubule-based molecular motor that can generate force to transport cargo in cells. The load dependence of the detachment rate is an important factor of the kinesin motor, the determination... Kinesin is an archetypal microtubule-based molecular motor that can generate force to transport cargo in cells. The load dependence of the detachment rate is an important factor of the kinesin motor, the determination of which is critically related to the chemomechanical coupling mechanism of the motor. Here, we use three models for the load dependence of the detachment rate of the kinesin motor to study theoretically and numerically the maximal force generated and microtubuleattachment duration of the motor. By comparing the theoretical and numerical results with the available experimental data,we show that only one model can explain well the available experimental data, indicating that only this model can be applicable to the kinesin motor. 展开更多
关键词 KINESIN detachment rate generated force chemomechanical coupling mechanism optical trapping
在线阅读 下载PDF
Md CIb HLH1 modulates sugar metabolism and accumulation in apple fruits by coordinating carbohydrate synthesis and allocation
12
作者 Jianqiang Yu Xiaolong Liu +7 位作者 Wenyan Wang Lili Zhang Chukun Wang Quanyan Zhang Jiahui Wang Mengchi Du Lixia Sheng Dagang Hu 《Horticultural Plant Journal》 2025年第2期578-592,共15页
The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple(Malus domestica Borkh.).Studying the patterns of accumulation of soluble sugars and regulatory mechanisms as... The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple(Malus domestica Borkh.).Studying the patterns of accumulation of soluble sugars and regulatory mechanisms associated with fruit development is crucial for breeding improved fruit varieties.Here,we report that MdCIbHLH1,a low temperature-induced b HLH transcription factor,inhibits the accumulation of soluble sugars by regulating sugar-metabolizing enzyme activities,photosynthetic performance,and the expression of sugar-related genes in developing apple fruits.MdCIbHLH1 inhibits MdFBP and MdPEPCK expression,thus blocking the conversion of acids to sugars in apple fruits.We also discovered that MdCIbHLH1 decreases the photosynthetic rate and carbohydrate accumulation in apple leaves.Our results suggest that soluble sugar accumulation in apple fruits is influenced by multiple factors,including metabolic status,photosynthesis,and carbohydrate allocation.MdCIbHLH1 is critically involved in controlling the accumulation of soluble sugars by coordinating carbohydrate synthesis and allocation,thus influencing sugar transport and its metabolism during the development of apple fruits. 展开更多
关键词 Fruit quality APPLE BHLH Sugar metabolism and transportation Photosynthetic rates
在线阅读 下载PDF
Effect of comprehensive perioperative nursing on pain intensity,complication rates,and comfort levels in patients undergoing gallstone surgery
13
作者 Chen-Yan Bao Xiao-Kun Ding +2 位作者 Qiao-Fei Qi Peng Ye Ze-Jun Fang 《World Journal of Gastrointestinal Surgery》 2025年第2期111-119,共9页
BACKGROUND Surgery is the gold standard for gallstone treatment.Nevertheless,the complications associated with the surgical procedure can exert diverse and adverse impacts on patients’health and quality of life to va... BACKGROUND Surgery is the gold standard for gallstone treatment.Nevertheless,the complications associated with the surgical procedure can exert diverse and adverse impacts on patients’health and quality of life to varying extents.Hence,it is essential to offer perioperative care to patients undergoing gallstone surgery.AIM To examine the impact of perioperative comprehensive nursing on pain intensity,complication rates,and patient comfort in individuals undergoing gallstone surgery.METHODS From February 2022 to February 2024,195 patients who underwent gallstone surgery at Sanmen People’s Hospital were selected and divided into two groups:A control group receiving routine nursing care(95 patients)and a research group receiving perioperative comprehensive nursing(100 patients).Key postoperative recovery indicators,including time to first postoperative anal exhaust,oral food intake,and ambulation,were observed,along with pain intensity(measured by the numeric rating scale),complication rate(bleeding,incision infection,recurrence),patient comfort(assessed using the visual analogue scale),and quality of life(measured by the World Health Organization Quality of Life-BREF).RESULTS The research group showed significantly shorter times to first postoperative anal exhaust,oral intake,and ambulation.Moreover,numeric rating scale pain scores in the research group were markedly lower post-nursing,and the total complication rate was significantly reduced compared to the control group.Furthermore,comfort levels improved considerably in the research group,and World Health Organization Quality of Life-BREF scores across the physical,psychological,social,and environmental domains were significantly higher compared to the control group following nursing care.CONCLUSION Perioperative comprehensive nursing effectively enhances postoperative recovery in patients undergoing gallstone surgery,reducing pain,lowering complications,and improving patient comfort and quality of life,which deserves clinical application. 展开更多
关键词 Perioperative comprehensive nursing Gallstone surgery Pain intensity Complication rate COMFORT
在线阅读 下载PDF
Dynamic tensile behaviour of rocks under confining pressure and high-rate loadings
14
作者 Kai Liu Chunjiang Zou Jian Zhao 《Earth Energy Science》 2025年第1期9-21,共13页
Tensile cracking is a predominant mode of failure in rocks within underground resource excavation and engineering structures,where rocks are frequently subjected to dynamic disturbances while simultaneously experienci... Tensile cracking is a predominant mode of failure in rocks within underground resource excavation and engineering structures,where rocks are frequently subjected to dynamic disturbances while simultaneously experiencing in-situ stresses.This paper proposes a new dynamic split tension setup utilising a cubic specimen to investigate the dynamic behaviour of rocks across various tensile strain rates and confining pressures.The objective is to extend the applicability of the triaxial Hopkinson bar in studying dynamic behaviour of geomaterials.For comparison,the dynamic Brazilian disc(BD)tests were performed using three rock types(e.g.,sandstone,granite and marble)under different strain rates ranging from 10^(−3)∼10^(2) s^(−1).Besides,the Digital Image Correlation(DIC)technique was adopted to measure full-field real-time tensile strain of rocks and demonstrated that tensile crack initiated at the middle part and split the specimen into two similar halves.Effects of specimen size,geometry,loading rate as well as the confining pressure are investigated in detail.The dynamic fracture behaviours,including dynamic tensile strength,tensile strain,time to fracture and dynamic increase factor(DIF),were characterised for the rocks.It is found that dynamic tensile strength of rock minimal dependence on size and geometry but is significantly influenced by loading rate and confinement.It exhibited a linear increase with strain rate(10^(0)∼10^(2) s^(−1))and demonstrated a nonlinear growth with lateral confinement from 0 to 15 MPa.The nonlinear dependency on confinement can be attributed to the restriction imposed on the opening and propagation of tensile cracks due to the presence of confinement.These findings enhance our understanding of the safety aspects associated with underground rock excavations,particularly in situations where considering in-situ stress is crucial for evaluating the dynamic tensile failure of rocks. 展开更多
关键词 Triaxial Hopkinson Bar Split tension High strain rate loads Confinement effect
在线阅读 下载PDF
In situ measurement of environmental γ radiation dose rates of key nuclides for large radioactive surface sources
15
作者 Ze-Qian Wu Jian Sun +7 位作者 Wei-Qi Huang Bai-Rong Wang Jin-Xing Cheng Jiang-Feng Wu Yong-Hong Wang Biao Yuan Sheng Qi Kun Shan 《Nuclear Science and Techniques》 2025年第1期69-79,共11页
To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.T... To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measuring the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGespectrometer to analyze the errors of the three aforementioned methods and verify their validity. 展开更多
关键词 Environmentalγradiation dose rate HPGespectrometer Key radionuclides Radioactive surface source
在线阅读 下载PDF
Thermal effects on the strain rate-dependent behavior of highly compacted GMZ01 bentonite
16
作者 Pengju Qin Weimin Ye +1 位作者 Qiong Wang Yonggui Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第1期453-464,共12页
Investigation of thermal effects on the strain rate-dependent properties of compacted bentonite is crucial for the long-term safety assessment of deep geological repository for disposal of high-level radioactive waste... Investigation of thermal effects on the strain rate-dependent properties of compacted bentonite is crucial for the long-term safety assessment of deep geological repository for disposal of high-level radioactive waste.In the present work,cylindrical GMZ01 bentonite specimens were compacted with suction-controlled by the vapor equilibrium technique.Then,a series of temperature-and suction-controlled stepwise constant rate of strain(CRS)tests was performed and the rate-dependent compressibility behavior of the highly compacted GMZ01 bentonite was investigated.The plastic compressibility parameterλ,the elastic compressibility parameterκ,the yield stress p0,as well as the viscous parameterαwere determined.Results indicate thatλ,κandαdecrease and p0 increases as suction increases.Upon heating,parametersλ,αand p0 decrease.It is also found that p0 increases linearly with increasing CRS in a double-logarithm coordinate.Based on the experimental results,a viscosity parameterα(s,T)was fitted to capture the effects of suction s and temperature T on the relationship between yield stress and strain rate.Then,an elastic-thermo-viscoplastic model for unsaturated soils was developed to describe the thermal effects on the rate-dependent behavior of highly compacted GMZ01 bentonite.Validation showed that the calculated results agreed well to the measured ones. 展开更多
关键词 Highly compacted bentonite rate-dependent behavior Constant rate of strain Temperature Elastic-thermo-viscoplastic model
在线阅读 下载PDF
Study on discharge characteristics of low-temperature sub-atmospheric pressure under steep change rate voltage
17
作者 Bo ZHU Ximu HAN +2 位作者 He SU Xiangjie MA Guoyan WU 《Plasma Science and Technology》 2025年第1期52-61,共10页
Aiming at the gas discharge problem in electric aircraft,this work studies the gas discharge characteristics at low-temperature sub-atmospheric pressure.A gas discharge shooting platform was built,and the discharge pr... Aiming at the gas discharge problem in electric aircraft,this work studies the gas discharge characteristics at low-temperature sub-atmospheric pressure.A gas discharge shooting platform was built,and the discharge process was photographed by intensified charge-coupled device(ICCD).A two-dimensional axisymmetric model of needle-plate electrode gas discharge was established,and three sets of Helmholtz equations were used to solve the photoionization.The results show that under the same voltage,the electric field intensity in the discharge process increases first,then decreases and finally increases again.The discharge speed increases with the increase of altitude,and the electron density in the streamer decreases with the increase of altitude.The development speed of the streamer in the middle stage is higher than that in the early stage,and the speed increases more obviously with the increase of altitude.The development speed of the streamer in the later stage is lower than that in the middle stage,but with the increase of altitude,the development speed of the streamer in the later stage is higher than that in the middle stage. 展开更多
关键词 electric aircraft gas discharge steep change rate voltage electric field intensity electron density
在线阅读 下载PDF
Flexibility versus Simplicity: A Comparative Study of Survival Models for HIV AIDS Failure Rates
18
作者 Nahashon Mwirigi 《Open Journal of Modelling and Simulation》 2025年第1期65-88,共24页
Modeling HIV/AIDS progression is critical for understanding disease dynamics and improving patient care. This study compares the Exponential and Weibull survival models, focusing on their ability to capture state-spec... Modeling HIV/AIDS progression is critical for understanding disease dynamics and improving patient care. This study compares the Exponential and Weibull survival models, focusing on their ability to capture state-specific failure rates in HIV/AIDS progression. While the Exponential model offers simplicity with a constant hazard rate, it often fails to accommodate the complexities of dynamic disease progression. In contrast, the Weibull model provides flexibility by allowing hazard rates to vary over time. Both models are evaluated within the frameworks of the Cox Proportional Hazards (Cox PH) and Accelerated Failure Time (AFT) models, incorporating critical covariates such as age, gender, CD4 count, and ART status. Statistical evaluation metrics, including Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), log-likelihood, and Pseudo-R2, were employed to assess model performance across diverse patient subgroups. Results indicate that the Weibull model consistently outperforms the Exponential model in dynamic scenarios, such as younger patients and those with co-infections, while maintaining robustness in stable contexts. This study highlights the trade-off between flexibility and simplicity in survival modeling, advocating for tailored model selection to balance interpretability and predictive accuracy. These findings provide valuable insights for optimizing HIV/AIDS management strategies and advancing survival analysis methodologies. 展开更多
关键词 HIV/AIDS Progression Survival Analysis Weibull Distribution Exponential Distribution Accelerated Failure Time (AFT) Model Cox Proportional Hazards (Cox PH) Model Hazard rate Modeling
在线阅读 下载PDF
Connection between heart rate variability alterations and cancer in tumor patients
19
作者 Yu-Zhu Deng Bing Song 《World Journal of Cardiology》 2025年第3期67-72,共6页
BACKGROUND A significant proportion of cancer patients experience autonomic dysfunction,and cancer treatments such as chemotherapy and radiation therapy can exacerbate impairments in the cardiac autonomic nervous syst... BACKGROUND A significant proportion of cancer patients experience autonomic dysfunction,and cancer treatments such as chemotherapy and radiation therapy can exacerbate impairments in the cardiac autonomic nervous system.This study sought to investigate the characteristics of heart rate variability(HRV)in individuals with cancer.AIM To evaluate the relationship between HRV and cancer patients,providing insights and references for cancer treatment.METHODS The study included 127 cancer patients with available 24-hour dynamic electrocardiogram data.HRV differences were analyzed using both time domain and frequency domain methods.These findings were then compared to HRV data from reference individuals,sourced from literature that utilized the same HRV computing algorithm.RESULTS Our findings revealed that cancer patients generally exhibited abnormal HRV compared to the reference group.HRV was found to be correlated with age and clinical type(P<0.05),but no significant correlation was observed with tumor site or gender(P>0.05).CONCLUSION This study indicates that cancer patients have significantly abnormal HRV compared to reference individuals,suggesting the presence of a certain level of cardiac autonomic dysfunction in this patient population. 展开更多
关键词 Cancer patients Heart rate variability Domain and frequency domain methods Autonomic dysfunction Dynamic electrocardiogram
在线阅读 下载PDF
Late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin in the North China Block and its seismological implications
20
作者 Li Lu-wei Yu Zhong-yuan +4 位作者 Qiu Chun-miao Wang Wen-xuan Zhao Qian Zheng Rong-ying Yang Yan-Lin 《Applied Geophysics》 2025年第1期53-70,232,233,共20页
Although the late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin(NFHB)was studied approximately 30 years ago using thermoluminescence and geomorphic methods,the underlying uncertainty cannot b... Although the late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin(NFHB)was studied approximately 30 years ago using thermoluminescence and geomorphic methods,the underlying uncertainty cannot be neglected,considering the limitations resulting from age and displacement measurements.Accordingly,we attempted to re-estimate the late Quaternary slip rate of the NFHB using high-precision remote sensing image interpretation,large-scale geological and geomorphic mapping,paleoseismic analysis,and Quaternary geochronology testing.The results,based on stratigraphic dislocation and age constraint in the trenches,show that the present deformation of the NFHB has been dominated by the extension,with a vertical slip rate~0.04-0.11 mm/a.We estimate a vertical slip rate of~0.06 mm/a,with an R^(2) value of~0.91,which is much lower than the~0.5 mm/a result estimated previously.There are three possible reasons for this discrepancy.The fi rst is the limitation resulting from dating and displacement measurements in earlier studies;the second is the slip decomposition caused by multiple branches of the NFHB,which leads to the low slip rate observed at a single fault;and third possible explanation is that the fault may be locked at present with a low slip rate,which means that the earthquake hazard of the NFHB cannot be ignored,and more in-depth research,such as geodetic and intensive observations of earthquake precursors,is urgently needed.This discovery poses a new challenge for the active study of the NFHB and the northeast corner of the Ordos Plateau in the North China Block. 展开更多
关键词 North China Block The Northern Margin Fault of the Huaizhuo Basin Late Quaternary slip rate Seismological Implications
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部