期刊文献+
共找到175,057篇文章
< 1 2 250 >
每页显示 20 50 100
Multi-objective optimization of grinding process parameters for improving gear machining precision 被引量:1
1
作者 YOU Tong-fei HAN Jiang +4 位作者 TIAN Xiao-qing TANG Jian-ping LU Yi-guo LI Guang-hui XIA Lian 《Journal of Central South University》 2025年第2期538-551,共14页
The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can caus... The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can cause changes in cutting force/heat,resulting in affecting gear machining precision.Therefore,this paper studies the effect of different process parameters on gear machining precision.A multi-objective optimization model is established for the relationship between process parameters and tooth surface deviations,tooth profile deviations,and tooth lead deviations through the cutting speed,feed rate,and cutting depth of the worm wheel gear grinding machine.The response surface method(RSM)is used for experimental design,and the corresponding experimental results and optimal process parameters are obtained.Subsequently,gray relational analysis-principal component analysis(GRA-PCA),particle swarm optimization(PSO),and genetic algorithm-particle swarm optimization(GA-PSO)methods are used to analyze the experimental results and obtain different optimal process parameters.The results show that optimal process parameters obtained by the GRA-PCA,PSO,and GA-PSO methods improve the gear machining precision.Moreover,the gear machining precision obtained by GA-PSO is superior to other methods. 展开更多
关键词 worm wheel gear grinding machine gear machining precision machining process parameters multi objective optimization
在线阅读 下载PDF
Shear behaviors of intermittent joints subjected to shearing cycles under constant normal stiffness conditions:Effects of loading parameters 被引量:1
2
作者 Bin Wang Yujing Jiang +1 位作者 Qiangyong Zhang Hongbin Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第5期2695-2712,共18页
A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that th... A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior. 展开更多
关键词 Intermittent joint Cyclic shear Loading parameter Constant normal stiffness(CNS)
在线阅读 下载PDF
Influence of Process Parameters on Forming Quality of Single-Channel Multilayer by Joule Heat Fuse Additive Manufacturing
3
作者 Li Suli Fan Longfei +3 位作者 Chen Jichao Gao Zhuang Xiong Jie Yang Laixia 《稀有金属材料与工程》 北大核心 2025年第5期1165-1176,共12页
To overcome the shortage of complex equipment,large volume,and high energy consumption in space capsule manufacturing,a novel sliding pressure Joule heat fuse additive manufacturing technique with reduced volume and l... To overcome the shortage of complex equipment,large volume,and high energy consumption in space capsule manufacturing,a novel sliding pressure Joule heat fuse additive manufacturing technique with reduced volume and low energy consumption was proposed.But the unreasonable process parameters may lead to the inferior consistency of the forming quality of single-channel multilayer in Joule heat additive manufacturing process,and it is difficult to reach the condition for forming thinwalled parts.Orthogonal experiments were designed to fabricate single-channel multilayer samples with varying numbers of layers,and their forming quality was evaluated.The influence of printing current,forming speed,and contact pressure on the forming quality of the single-channel multilayer was analyzed.The optimal process parameters were obtained and the quality characterization of the experiment results was conducted.Results show that the printing current has the most significant influence on the forming quality of the single-channel multilayer.Under the optimal process parameters,the forming section is well fused and the surface is continuously smooth.The surface roughness of a single-channel 3-layer sample is 0.16μm,and the average Vickers hardness of cross section fusion zone is 317 HV,which lays a foundation for the subsequent use of Joule heat additive manufacturing technique to form thinwall parts. 展开更多
关键词 Joule heat additive manufacturing single-channel multilayer process parameter forming quality
原文传递
An identification model for weak influence parameters of nuclear power unit based on parameter recursion
4
作者 LIANG Qian-Yun XU Xin 《四川大学学报(自然科学版)》 北大核心 2025年第4期986-991,共6页
In complex systems,there is a kind of parameters having only a minor impact on the outputs in most cases,but their accurate values are still critical for the operation of systems.In this paper,the authors focus on the... In complex systems,there is a kind of parameters having only a minor impact on the outputs in most cases,but their accurate values are still critical for the operation of systems.In this paper,the authors focus on the identification of these weak influence parameters in the complex systems and propose a identification model based on the parameter recursion.As an application,three parameters of the steam generator are identified,that is,the valve opening,the valve CV value,and the reference water level,in which the valve opening and the reference water level are weak influence parameters under most operating conditions.Numerical simulation results show that,in comparison with the multi-layer perceptron(MLP),the identification error rate is decreased.Actually,the average identification error rate for the valve opening decreases by 0.96%,for the valve CV decreases by 0.002%,and for the reference water level decreases by 12%after one recursion.After two recursions,the average identification error rate for the valve opening decreases by 11.07%,for the valve CV decreases by 2.601%,and for the reference water level decreases by 95.79%.This method can help to improve the control of the steam generator. 展开更多
关键词 Steam generator Nuclear power Parameter identification Multi-layer perceptron
在线阅读 下载PDF
Learning the parameters of a class of stochastic Lotka-Volterra systems with neural networks
5
作者 WANG Zhanpeng WANG Lijin 《中国科学院大学学报(中英文)》 北大核心 2025年第1期20-25,共6页
In this paper,we propose a neural network approach to learn the parameters of a class of stochastic Lotka-Volterra systems.Approximations of the mean and covariance matrix of the observational variables are obtained f... In this paper,we propose a neural network approach to learn the parameters of a class of stochastic Lotka-Volterra systems.Approximations of the mean and covariance matrix of the observational variables are obtained from the Euler-Maruyama discretization of the underlying stochastic differential equations(SDEs),based on which the loss function is built.The stochastic gradient descent method is applied in the neural network training.Numerical experiments demonstrate the effectiveness of our method. 展开更多
关键词 stochastic Lotka-Volterra systems neural networks Euler-Maruyama scheme parameter estimation
在线阅读 下载PDF
Effect of total knee arthroplasty on the spinopelvic parameters: A systemic review and metanalysis
6
作者 Mantu Jain Deb Kumar Pal +3 位作者 Rabi Narayan Sahu Bikash Ranjan Meher Binod Kumar Patro Sujit Kumar Tripathy 《World Journal of Orthopedics》 2025年第7期126-133,共8页
BACKGROUND Sagittal spinopelvic alignment(SSA)is essential for preserving a stable and effective upright posture and locomotion.Although alterations in the SSA are recognised to induce compensatory modifications in th... BACKGROUND Sagittal spinopelvic alignment(SSA)is essential for preserving a stable and effective upright posture and locomotion.Although alterations in the SSA are recognised to induce compensatory modifications in the pelvis,hips,and knees,the inverse relationship concerning knee pathology undergoing total knee arthroplasty(TKA)has been examined by a limited number of studies,yielding inconclusive results.AIM To generate evidence of the effect of TKA on the SSA from existing literature.METHODS Databases like PubMed,EMBASE,and Scopus were used to identify articles related to the“knee spine syndrome”phenomenon using a combination of subject terms and keywords such as“spinopelvic parameters”,“sagittal spinal balance”,and“total knee arthroplasty”were used with appropriate Boolean operators.Studies measuring the SSA following TKA were included,and research was conducted as per preferred reporting items for systematic review and metaanalysis guidelines.RESULTS A total of 475 participants had undergone TKA,and six studies measuring SSA were analysed.Following TKA,pelvic tilt was the only parameter that showed significant changes,while lumbar lordosis(LL),pelvic incidence,and sacral slope were non-significant,as evident from the forest plots.CONCLUSION The body's sagittal alignment is a complex balance between pelvic,spine,and lower extremity parameters.TKA,while having the potential to correct the flexion contracture,can also correct it.Still,the primary SSA for spinal pathology,i.e.,LL,may not be corrected in patients with co-existent spinal degenerative disease. 展开更多
关键词 Spinopelvic parameters Total knee arthroplasty Pelvic parameters Lower extremities parameters META-ANALYSIS
在线阅读 下载PDF
Influence of Processed Mustard Seed Meals on Growth and Health Parameters in Indian Major Carps
7
作者 Shivanshu Garg Himanshu Punetha +8 位作者 Anant Deogaonkar Deepshree Kumar Ashutosh Mishra AshokKumar Verma Nityanand Pandey Ranjeet Singh Saurabh Gangola Sunil Kumar Amit Mittal 《Research in Ecology》 2025年第2期93-105,共13页
The current investigation focuses on intertwined relationships of ecology and aquaculture for the benefit of farmers involved in fish farming practices.The study evaluated glucosinolate reduction in black,brown,and wh... The current investigation focuses on intertwined relationships of ecology and aquaculture for the benefit of farmers involved in fish farming practices.The study evaluated glucosinolate reduction in black,brown,and white mustard meals as fish feed ingredients for Indian Major Carps.Fish were fed with 10%mustard meal-supplemented diets in three forms:Raw(R),Anti-nutritional Rich(AR),and Anti-nutritional Lowered(AL),alongside a control group using floating feed.The three-month indoor experiment(September-November 2023)was conducted in FRP tanks with triplicate treatments.Blood analysis revealed compromised health in AR-fed carps,with reduced hemoglobin levels in rohu,catla and mrigal and elevated total leukocyte counts indicating inflammation in all the three carps studied here.Liver function was impaired in AR-fed fish,shown by increased alanine transaminase levels,highest in rohu followed by mrigal and catla.Histopathological examination of AR-fed carps liver tissue revealed necrotic spots,deformed hepatocytes,and significant vacuolation.In contrast,AL-fed fish demonstrated improved health parameters through Complete Blood Count analysis,liver function tests,and histo-pathological observations,suggesting successful reduction of anti-nutritional factors in the processed mustard meals.In near future,replacement of unprocessed seed meal with processed seed meal will lead to economic gains in fish farming. 展开更多
关键词 Biochemical parameters GLUCOSINOLATES Growth parameters Histo-Pathological Analysis Indian Major Carps Liver Function Test
在线阅读 下载PDF
Growth Parameters and Condition Coefficient of Three Species from Bas-Kouilou (Congo Brazzaville): Chrysichthys auratus, Geoffroy, 1809, Liza falcipinnis, Valenciennes, 1836 and Pellonula vorax, Gunther, 1868
8
作者 Marcellin Mikia Anthelme Tsoumou +1 位作者 Durelle Brith Caëlle Olabi-Obath Isabelle Mady-Goma Dirat 《Open Journal of Ecology》 2025年第1期100-114,共15页
The study of the morphometric parameters of the three most abundant species in the lower course of the Kouilou River (Chrysichthys auratus, Liza falcipinnis and Pellonula vorax) was carried out. The standard length of... The study of the morphometric parameters of the three most abundant species in the lower course of the Kouilou River (Chrysichthys auratus, Liza falcipinnis and Pellonula vorax) was carried out. The standard length of Chrysichthys auratus varies between 43.57 and 210 mm, for an average of 96.70 ± 28.63 mm;the weight varies between 2.92 and 140.83 mg, an average of 73.03 ± 21.62 mg. The condition coefficient is equal to 4.42 ± 1.52. Liza falcipinnis has a standard length which varies between 59.9 mm and 158.08 mm for an average of 88.15 ± 29.74 mm;its weight varies between 4.77 and 76.21 mg, an average of 18.61 ± 11.82 mg. The condition coefficient is equal to 2.47 ± 1.57. Pellonula vorax has a standard length which varies between 60.33 mm and 117.72 mm;for an average of 80.48 ± 17.75 mm;the weight varies between 3.61 and 25.17 mg, an average of 9.03 ± 3.61 mg. The condition coefficient is equal to 2.17 ± 0.57. These three species have a minor allometric growth. 展开更多
关键词 Kouilou River Chrysichthys auratus Liza falcipinnis Pellonula vorax Growth parameters Condition Coefficient
在线阅读 下载PDF
Orientation Parameters Estimation and Lens Distortion Correction for UAVs Photogrammetry with Non-metric Cameras
9
作者 DENG Xingsheng GAO Yang ZHU Xu 《Journal of Geodesy and Geoinformation Science》 2025年第1期71-88,共18页
The estimation of orientation parameters and correction of lens distortion are crucial problems in the field of Unmanned Aerial Vehicles(UAVs)photogrammetry.In recent years,the utilization of UAVs for aerial photogram... The estimation of orientation parameters and correction of lens distortion are crucial problems in the field of Unmanned Aerial Vehicles(UAVs)photogrammetry.In recent years,the utilization of UAVs for aerial photogrammetry has witnessed a surge in popularity.Typically,UAVs are equipped with low-cost non-metric cameras and a Position and Orientation System(POS).Unfortunately,the Interior Orientation Parameters(IOPs)of the non-metric cameras are not fixed.Whether the lens distortions are large or small,they effect the image coordinates accordingly.Additionally,Inertial Measurement Units(IMUs)often have observation errors.To address these challenges and improve parameter estimation for UAVs Light Detection and Ranging(LiDAR)and photogrammetry,this paper analyzes the accuracy of POS observations obtained from Global Navigation Satellite System Real Time Kinematic(GNSS-RTK)and IMU data.A method that incorporates additional known conditions for parameter estimation,a series of algorithms to simultaneously solve for IOPs,Exterior Orientation Parameters(EOPs),and camera lens distortion correction parameters are proposed.Extensive experiments demonstrate that the coordinates measured by GNSS-RTK can be directly used as linear EOPs;however,angular EOP measurements from IMUs exhibit relatively large errors compared to adjustment results and require correction during the adjustment process.The IOPs of non-metric cameras vary slightly between images but need to be treated as unknown parameters in high precision applications.Furthermore,it is found that the Ebner systematic error model is sensitive to the choice of the magnification parameter of the photographic baseline length in images,it should be set as less than or equal to one third of the photographic baseline to ensure stable solutions. 展开更多
关键词 UAVs photogrammetry non-metric cameras Interior Orientation parameters(IOPs) Exterior Orientation parameters(EOPs) lens distortion correction
在线阅读 下载PDF
Effect of Design Parameters on the Properties of PLA Biocomposites Fabricated via Fused Filament Deposition
10
作者 Martha L.Sánchez Luz Y.Morales Gil Capote 《Journal of Renewable Materials》 2025年第7期1413-1437,共25页
The use of additive manufacturing techniques in the development of unconventional materials can help reduce the environmental impact of traditional construction materials.In this paper,the properties of a 3D-printed b... The use of additive manufacturing techniques in the development of unconventional materials can help reduce the environmental impact of traditional construction materials.In this paper,the properties of a 3D-printed biocomposite were evaluated.Biofilaments obtained by mixing pulverized bamboo fibers with polylactic acid(PLA)resin were extruded during the manufacturing process.To assess the effect of incorporating plant fibers,an analysis was conducted on the morphology,elemental chemical composition,crystallinity index,principal functional groups,thermal stability,surface roughness,microhardness,density,tensile strength,elastic modulus,and strain percentage of reinforced samples.The results were comparedwith those obtained from the characterization of standard PLAfilaments(unreinforced).The fused deposition modeling(FDM)technique was employed to print biocomposite specimens.Additionally,the influence of the printing parameters(infill density,build orientation,and layer thickness)on the physical,tribological,andmechanical properties of the biocomposites was analyzed.These results were compared with those obtained for specimens printed with pure PLA.The findings indicate that incorporating 10%vegetable filler into PLA filaments enhanced the strength and stiffness of the biocomposite under axial loads.Finally,the strength of the biocomposite subjected to axial loads was compared with the standardized values for wood-plastic composites,demonstrating the feasibility of its use for non-structural purposes in civil construction. 展开更多
关键词 BIOCOMPOSITES biofilaments 3D printing fused deposition modeling printing parameters mechanical properties
在线阅读 下载PDF
Towards improved neonatal care:Developing reference intervals for biochemical parameters in umbilical cord blood:An Indian study
11
作者 Keyur Sabnis Swati Ghanghurde +2 位作者 Akash Shukla Dhriti Sukheja Mohit Vijay Rojekar 《World Journal of Clinical Pediatrics》 2025年第4期340-347,共8页
BACKGROUND The reference ranges for biochemical parameters can fluctuate due to factors like altitude,age,gender,and socioeconomic conditions.These values are crucial for interpreting laboratory data and guide clinica... BACKGROUND The reference ranges for biochemical parameters can fluctuate due to factors like altitude,age,gender,and socioeconomic conditions.These values are crucial for interpreting laboratory data and guide clinical treatment decisions.Currently,there is no established set of reference intervals for cord blood biochemical parameters of newborns in India,particularly in Mumbai.AIM To create cord blood biochemical parameters reference intervals specifically for Mumbai,India.METHODS A cross-sectional study was conducted in an Indian tertiary care hospital.This study focused on healthy newborns with normal birth weight,born to pregnant mothers without health issues.Cord blood samples,approximately 2-3 mL in volume,were collected from 210 term neonates.These samples were divided into fluoride(glucose)and clot activator(serum)tubes and were subsequently analyzed in the institute's biochemical laboratory.The data obtained from the analysis was then subjected to statistical analysis.The result of the Shapiro-Wilk test suggested non-normality in the data distribution.Consequently,nonparametric statistics were utilized for analysis.The Mann-Whitney U test was utilized to compare parameter distributions among different factors,including the infant’s sex,delivery method,maternal age,and obstetric history.A significance level of P<0.05 was considered to indicate statistical significance.RESULTS The following represent the median figures and central 95 percentile reference intervals for biochemical parameters in umbilical cord blood of newborns:Serum direct bilirubin=(0.1-0.55)mg/dL,indirect bilirubin=(0.64-2.26)mg/dL,total bilirubin=(0.62-3.14)mg/dL,creatinine=(0.27-0.76)mg/dL,sodium=(128.19-143.26)mmol/L,chloride=(100.19-111.68)mmol/L,potassium=(1.62-9.98)mmol/L and plasma glucose=(24.75-94.23)mg/dL.Statistically significant differences were observed in serum sodium,potassium,and plasma glucose levels when comparing delivery modes.CONCLUSION This is the pioneering study in which first time,the biochemical reference intervals in cord blood for newborns are established in western India.The values are applicable for newborns from this area.Larger study throughout the country is required. 展开更多
关键词 Biochemical parameters Reference interval Umbilical cord blood Peripheral venous blood NEONATES INDIA
暂未订购
Development and validation of a nomogram model for predicting the risk of H-type hypertension with pulse diagram parameters
12
作者 Siman WANG Mengchu ZHANG +4 位作者 Minghui YAO Tianxiao XIE Rui GUO Yiqin WANG Haixia YAN 《Digital Chinese Medicine》 2025年第2期174-182,共9页
Objective To develop an onset risk prediction nomogram for patients with homocysteine-type(H-type)hypertension(HTH)based on pulse diagram parameters to assist early clinical prediction and diagnosis of HTH.Methods Pat... Objective To develop an onset risk prediction nomogram for patients with homocysteine-type(H-type)hypertension(HTH)based on pulse diagram parameters to assist early clinical prediction and diagnosis of HTH.Methods Patients diagnosed with essential hypertension and admitted to Shanghai Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine,Shang-hai Hospital of Traditional Chinese Medicine,and Shanghai Hospital of Integrated Tradition-al Chinese and Western Medicine from July 6th 2020 to June 16th 2021,and from August 11th 2023 to January 22nd 2024,were enrolled in this retrospective research.The baselines and clinical biochemical indicators of patients were collected.The SMART-I TCM pulse instru-ment was applied to gather pulse diagram parameters.Multivariate logistic regression was adopted to analyze the risk factors for HTH.RStudio was employed to construct the nomo-gram model,receiver operating characteristic(ROC)curve,and calibration curve(bootstrap self-sampling 200 times),and clinical decision curve were drawn to evaluate the model’s dis-crimination and clinical effectiveness.Results A total of 168 hospitalized patients with essential hypertension were selected and di-vided into non-HTH group(n=29)and HTH group(n=139).Compared with non-HTH group,HTH group had a lower body mass index(BMI),and higher proportions of male pa-tients and drinkers(P<0.05).The ventricular wall thickening(VWT)could not be deter-mined.The proportions of left common carotid intima-media wall thickness(LCCIMWT)and serum creatinine(SCR)were higher in HTH group(P<0.05).The pulse diagram parameter As was significantly higher,and H4/H1 and T1/T were lower in HTH group(P<0.05).Gender,al-cohol consumption,serum creatinine,and the pulse diagram parameter H4/H1 were identi-fied as independent risk factors for HTH(P<0.05).The nomogram’s area under the ROC curve(AUC)was 0.795[95%confidence interval(CI):(0.7066,0.8828)],with a specificity of 0.724 and sensitivity of 0.799.After 200 times repeated bootstrap self-samplings,the calibra-tion curve showed that the simulated curve fits well with the actual curve(x^(2)=9.5002,P=0.3019).The clinical decision curve indicated that the nomogram’s applicability was optimal when the threshold for predicting HTH was between 0.38 and 1.00.Conclusion The nomogram model could be valuable for predicting the onset risk of HTH and pulse diagram parameters can facilitate early screening and prevention of HTH. 展开更多
关键词 H-type hypertension Homocysteine NOMOGRAM Pulse diagram parameters Prediction model
暂未订购
Micronucleus counts correlating with male infertility:a clinical analysis of chromosomal abnormalities and reproductive parameters
13
作者 Shun-Han Zhang Ying-Jun Xie +6 位作者 Wen-Jun Qiu Qian-Ying Pan Li-Hao Chen Jian-Feng Wu Si-Qi Huang Ding Wang Xiao-Fang Sun 《Asian Journal of Andrology》 2025年第4期537-542,共6页
Investigating the correlation between micronucleus formation and male infertility has the potential to improve clinical diagnosis and deepen our understanding of pathological progression. Our study enrolled 2252 male ... Investigating the correlation between micronucleus formation and male infertility has the potential to improve clinical diagnosis and deepen our understanding of pathological progression. Our study enrolled 2252 male patients whose semen was analyzed from March 2023 to July 2023. Their clinical data, including semen parameters and age, were also collected. Genetic analysis was used to determine whether the sex chromosome involved in male infertility was abnormal (including the increase, deletion, and translocation of the X and Y chromosomes), and subsequent semen analysis was conducted for clinical grouping purposes. The participants were categorized into five groups: normozoospermia, asthenozoospermia, oligozoospermia, oligoasthenozoospermia, and azoospermia. Patients were randomly selected for further study;41 patients with normozoospermia were included in the control group and 117 patients with non-normozoospermia were included in the study group according to the proportions of all enrolled patients. Cytokinesis-block micronucleus (CBMN) screening was conducted through peripheral blood. Statistical analysis was used to determine the differences in micronuclei (MNi) among the groups and the relationships between MNi and clinical data. There was a significant increase in MNi in infertile men, including those with azoospermia, compared with normozoospermic patients, but there was no significant difference between the genetic and nongenetic groups in azoospermic men. The presence of MNi was associated with sperm concentration, progressive sperm motility, immotile spermatozoa, malformed spermatozoa, total sperm count, and total sperm motility. This study underscores the potential utility of MNi as a diagnostic tool and highlights the need for further research to elucidate the underlying mechanisms of male infertility. 展开更多
关键词 chromosome instability genetic azoospermia male infertility MICRONUCLEUS semen parameters
原文传递
In-flight measurement method and application research of helicopter rotor blade motion parameters
14
作者 Jiahong ZHENG Weizhen CHENG +2 位作者 Yan LI Shuaike JIAO Xide LI 《Chinese Journal of Aeronautics》 2025年第9期190-207,共18页
Accurate measurement of helicopter rotor motion parameters(flap,lead-lag,torsion,and azimuth angles)is essential for rotor blade design,helicopter dynamics modeling,and flight safety and health monitoring.However,the ... Accurate measurement of helicopter rotor motion parameters(flap,lead-lag,torsion,and azimuth angles)is essential for rotor blade design,helicopter dynamics modeling,and flight safety and health monitoring.However,the existing methods face challenges in testing equipment installation,calibration,and data transmission,resulting in limited reports on real-time in-flight measurements of blade motion parameters.This paper proposes a non-contact optoelectronic method based on two-dimensional position-sensitive detectors for in-flight measurement and a ground calibration system to obtain real-time rotor motion parameters during helicopter flight.The proposed method establishes the time evolution relationship of rotor motion parameters and verifies the performance of the in-flight measurement system regarding measurement resolution and accuracy through the construction of a blade motion posture experimental platform.The proposed method has been applied to the flight measurement of a medium-sized single-rotor helicopter,and the obtained results have been compared with theoretical analysis outcomes.Furthermore,this paper examines the characteristics of blade motion parameters during flight and discusses the challenges and potential solutions for measuring rotor motion parameters during helicopter flight using the proposed method. 展开更多
关键词 Blade motion parameters Flight test Helicopter rotors MEASUREMENT Optical instruments Position sensitive detector
原文传递
Correlation between prognostic markers and clinical parameters in hepatocellular carcinoma:Pathophysiological aspects to therapeutic targets
15
作者 Saira Rafaqat Iqra Noshair +3 位作者 Momina Shahid Sadaf Bibi Ramsha Hafeez Hafsa Hamid 《World Journal of Gastrointestinal Oncology》 2025年第5期9-26,共18页
One of the main causes of cancer-related morbidity and mortality globally is hepatocellular carcinoma(HCC).At every stage of the disease,HCC may now be treated using a variety of therapy techniques.Nevertheless,despit... One of the main causes of cancer-related morbidity and mortality globally is hepatocellular carcinoma(HCC).At every stage of the disease,HCC may now be treated using a variety of therapy techniques.Nevertheless,despite the abundance of effective therapeutic choices,the prognosis for patients with HCC is still typically dismal.Prognostic indicators are crucial when assessing prognosis and tracking tumor metastases or recurrence.There are many prognostic markers in HCC.We mainly focused on newly reported prognostic markers such as MEX3A,apolipoprotein B,alpha-fetoprotein,circulating tumor cells,SAMD13,Agrin,and Glypican-3 in the pathogenesis of HCC.Further,we highlighted how these prognostic markers correlated to clinical parameters such as tumor node metastasis,tumor diameter,differentiation,hepatocirrhosis,vascular invasion,and others in HCC.Therefore,identifying specific prognostic biomarkers of HCC helps to provide a great opportunity to improve the prognosis in patients with HCC and provide therapeutic targets. 展开更多
关键词 Hepatocellular carcinoma Clinical parameters Prognostic markers Pathophysiological aspects Therapeutic targets
暂未订购
A Hybrid Simulation-Experimental Method for Deriving Equivalent Dynamic Parameters of O-Ring Support Systems
16
作者 LIU Yi YE He +3 位作者 ZHANG Lingfeng LI Shujia CHEN Ge WANG Yongxing 《Journal of Donghua University(English Edition)》 2025年第4期425-434,共10页
The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critica... The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critical speed points and maintain operational stability across the entire working speed range.However,the support stiffness and damping of rubber O-rings exhibit significant nonlinear frequency dependence.Conventional experimental methods for deriving equivalent stiffness and damping,based on the principle of the forced non-resonance method,require fabricating custom setups for each O-ring specification and conducting vibration tests at varying frequencies,resulting in low efficiency and high costs.This study proposes a hybrid simulation-experimental method for dynamic parameter identification.Firstly,the frequency-dependent dynamic parameters of a specific O-ring support system are experimentally obtained.Subsequently,a corresponding parametric finite element model is established to simulate and solve the equivalent elastic modulus and equivalent stiffness-damping coefficient of this O-ring support system.Ultimately,after iterative simulation,the simulated and experimental results achieve a 99.7%agreement.The parametric finite element model developed herein can directly simulate and inversely estimate frequency-dependent dynamic parameters for O-rings of different specifications but identical elastic modulus. 展开更多
关键词 O-RING equivalent dynamic parameter forced non-resonance method inverse parameter estimation dynamic simulation
在线阅读 下载PDF
Hematological parameters in atrial fibrillation:A literature review
17
作者 Saira Rafaqat Ali Hassan +6 位作者 Ahmad Usman Iman Hussain Aneeza Waris Hussain Rathore Muhammad Faheem Tariq Hooria Naseem Sara Khan Masooma Zaidi 《World Journal of Cardiology》 2025年第7期124-142,共19页
Atrial fibrillation(AF)is a frequent cardiac arrhythmia in the general population,which is associated with an increased risk of several health issues.It has been demonstrated that hematological variables predict the o... Atrial fibrillation(AF)is a frequent cardiac arrhythmia in the general population,which is associated with an increased risk of several health issues.It has been demonstrated that hematological variables predict the occurrence and recurrence of AF.This review article specifically only focuses on haemoglobin,hematocrit,platelet count,white blood cells(WBCs),lymphocytes,neutrophils,monocytes,neutrophil-to-lymphocyte ratio(NLR),monocyte-to-lymphocyte ratio(MLR),platelet-to-lymphocyte ratio(PLR)and red blood cells in the pathophysiology of AF.It emphasizes that there is a higher risk of new-onset AF linked with both low and high haemoglobin levels.A quantitative investigation showed that hematocrit is not linked to the development of AF.The predictive significance of platelet count was reported in nonvalvular AF patients.WBCs are consistent inflammatory markers that are associated with postoperative new-onset AF.Inflammation and in particular,leukocyte activation predisposes to AF.Enhanced migratory activity in circulating and local monocytes may play a pivotal role in the pathogenesis of progression in atrial remodeling in AF patients.In particular,the peripheral eosinophil and left atrial diameter may be important in mediating inflammation and atrial remodeling in AF.In nonvalvular AF patients,PLR may be an independent risk factor for left atrial appendage thrombogenic milieu.NLR and MLR changes are associated with early recurrence of AF,and NLR change is related to late recurrence of AF after pulmonary vein isolation.Red blood cell distribution width and left atrial dimension were the only independent risk factors associated with AF. 展开更多
关键词 Atrial fibrillation Hematological parameters Blood cells Red blood cells White blood cells PLATELETS
暂未订购
Effect of MeJA at Different Concentrations on Photosynthetic Parameters and Chlorophyll Fluorescence Parameters of Malus spectabilis Seedlings Under O_(3) Stress
18
作者 WANG Yan-ling SUN Shu-qi +3 位作者 XU Chang CHEN Lin GUO Ying-ying ZHANG Hui 《Agricultural Science & Technology》 2025年第2期18-24,共7页
This study aimed to decipher the mechanism by which exogenous methyl jasmonate(MeJA)regulated the photosynthesis of Malus spectabilis leaves under ozone(O_(3))stress.The photosynthetic parameters and chlorophyll fluor... This study aimed to decipher the mechanism by which exogenous methyl jasmonate(MeJA)regulated the photosynthesis of Malus spectabilis leaves under ozone(O_(3))stress.The photosynthetic parameters and chlorophyll fluorescence parameters of M.spectabilis‘Hongjiu’seedlings under O_(3)stress were measured by spraying different concentrations of MeJA.The results showed that O_(3)stress significantly reduced the chlorophyll a and total chlorophyll content,net photosynthetic rate(Pn),stomatal conductance(G_(s)),transpiration rate(T_(r)),maximum fluorescence yield(F_(m)),maximum quantum yield of photosystem II(F_(v)/F_(m)),and actual photochemical efficiency of photosystem II(Ф_(PSII)),while increasing the intercellular CO_(2)concentration(Ci).Exogenous MeJA reduced the Ci and original fluorescence yield(Fo),while increasing chlorophyll a,chlorophyll b,and total chlorophyll content,P_(n),G_(s),T_(r),F_(m),F_(v)/F_(m),andФ_(PSII) of the leaves under O_(3)stress.The application of 150μmol/L MeJA showed the best effect.The above results demonstrated that exogenous MeJA could enhance chlorophyll content and photosynthetic capacity,thereby improving the tolerance of M.spectabilis to O_(3)stress. 展开更多
关键词 Methyl jasmonate Ozone stress Malus spectabilis Photosynthetic parameters Chlorophyll fluorescence
在线阅读 下载PDF
Association between metabolic parameters and erection in erectile dysfunction patients with hyperuricemia
19
作者 Guo-Wei Du Pei-Ning Niu +6 位作者 Zhao-Xu Yang Xing-Hao Zhang Jin-Chen He Tao Liu Yan Xu Jian-Huai Chen Yun Chen 《Asian Journal of Andrology》 2025年第4期482-487,共6页
The relationship between hyperuricemia(HUA)and erectile dysfunction(ED)remains inadequately understood.Given that HUA is often associated with various metabolic disorders,this study aims to explore the multivariate li... The relationship between hyperuricemia(HUA)and erectile dysfunction(ED)remains inadequately understood.Given that HUA is often associated with various metabolic disorders,this study aims to explore the multivariate linear impacts of metabolic parameters on erectile function in ED patients with HUA.A cross-sectional analysis was conducted involving 514 ED patients with HUA in the Department of Andrology,Jiangsu Province Hospital of Chinese Medicine(Nanjing,China),aged 18 to 60 years.General demographic information,medical history,and laboratory results were collected to assess metabolic disturbances.Sexual function was evaluated using the 5-item version of the International Index of Erectile Function(IIEF-5)questionnaire.Based on univariate analysis,variables associated with IIEF-5 scores were identified,and the correlations between them were evaluated.The effects of these variables on IIEF-5 scores were further explored by multiple linear regression models.Fasting plasma glucose(β=−0.628,P<0.001),uric acid(β=−0.552,P<0.001),triglycerides(β=−0.088,P=0.047),low-density lipoprotein cholesterol(β=−0.164,P=0.027),glycated hemoglobin(HbA1c;β=−0.562,P=0.012),and smoking history(β=−0.074,P=0.037)exhibited significant negative impacts on erectile function.The coefficient of determination(R²)for the model was 0.239,and the adjusted R²was 0.230,indicating overall statistical significance(F-statistic=26.52,P<0.001).Metabolic parameters play a crucial role in the development of ED.Maintaining normal metabolic indices may aid in the prevention and improvement of erectile function in ED patients with HUA. 展开更多
关键词 erectile dysfunction HYPERURICEMIA IIEF-5 metabolic parameters multivariate linear regression
原文传递
Evaluating the accuracy of earth rotation parameters based on the BDS observations
20
作者 Chenxiang Wang Pengfei Zhang +3 位作者 Tengxu Zhang Ziyu Shen Jizhang Sang Wenbin Shen 《Geodesy and Geodynamics》 2025年第1期87-98,共12页
The Bei Dou satellite system(BDS)has progressed with the full operationalization of the secondgeneration regional system(BDS-2)and the third-generation global system(BDS-3).This technology plays a crucial role in dete... The Bei Dou satellite system(BDS)has progressed with the full operationalization of the secondgeneration regional system(BDS-2)and the third-generation global system(BDS-3).This technology plays a crucial role in determining Earth Rotation Parameters(ERPs).In this study,we determine the ERPs based on the observations of BDS-2,BDS-3 and BDS-2+BDS-3,with the time spanning from August18,2022,to August 18,2023.The IERS EOP 20C04 series is used as a reference to evaluate the accuracy of the ERP estimates.We analyze the impact of different numbers of reference stations,polyhedron volumes,observation arc lengths,satellite types,and satellite systems on solving ERPs using BDS-2 and BDS-3 observation data provided by the International GNSS Service(IGS)stations.When selecting a specific satellite type,it is necessary to choose an appropriate observation arc length based on different numbers of reference stations while maximizing the volume of the formed polyhedron to achieve optimal efficiency and accuracy in parameter estimation.When both the number of reference stations and observation arc length are fixed,higher precision of the ERPs can be achieved using observations from MEO than MEO+IGSO and MEO+IGSO+GEO.Moreover,when considering only IGSO and MEO satellites as options for analysis purposes,BDS-3 provides higher accuracy compared to BDS-2.In summary,when using BDS for ERP estimation and MEO satellite observations with the same observation arc length,selecting stations from reference stations with larger polyhedral volumes can significantly improve the efficiency and accuracy of parameter estimation. 展开更多
关键词 Earth rotation parameters Polyhedron volume Observation arc length BDS-2 BDS-3
原文传递
上一页 1 2 250 下一页 到第
使用帮助 返回顶部