期刊文献+
共找到89篇文章
< 1 2 5 >
每页显示 20 50 100
Evaluation of the Effectiveness and Efficiency of the Combination of Levamlodipine Besylate and Valsartan in the Treatment of Hypertension
1
作者 Dazhuan Li 《Proceedings of Anticancer Research》 2024年第1期92-98,共7页
Objective:To investigate the effectiveness and efficiency of combining levamlodipine besylate and valsartan in the treatment of hypertension.Methods:This study selected 28 patients with hypertension as observation sub... Objective:To investigate the effectiveness and efficiency of combining levamlodipine besylate and valsartan in the treatment of hypertension.Methods:This study selected 28 patients with hypertension as observation subjects.The treatment duration ranged from January 2020 to June 2023.Using the random number table method,patients were divided into two groups.The control group received treatment with valsartan,while the observation group received a combination of valsartan and levamlodipine besylate.Therapeutic effects and safety were compared between the groups,and changes in the patient’s blood pressure and renal function index levels were assessed.Results:The total clinical effective rate of the observation group was significantly higher than that of the control group(P<0.05).The observation group demonstrated better diastolic blood pressure,systolic blood pressure,and renal function indicators compared to the control group(P<0.05).There was no significant difference in the incidence of adverse reactions between the two groups(P>0.05).Conclusion:The combined treatment of levamlodipine besylate and valsartan in patients with hypertension showed significant clinical efficacy and holds broad application value. 展开更多
关键词 Levamlodipine besylate VALSARTAN HYPERTENSION Renal function effective rate
下载PDF
Bending Strength of Glass Materials under Strong Dynamic Impact and Its Strain Rate Effects
2
作者 LIU Xiaogen QI Shuang +2 位作者 WEI Shaoshan WAN Detian JIN Chunxia 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第6期1358-1364,共7页
Based on the structural characteristics of the high-speed loading tester,a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and dif... Based on the structural characteristics of the high-speed loading tester,a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and different impact velocities,and the formulae for calculating the maximum dynamic stress and strain rate of glass specimens under the action of impact loads were derived.The experimental results show that the bending strength values of the glass under dynamic impact loading are all higher than those under static loading.With the increase of impact speed,the bending strength value of glass specimens generally tends to increase,and the bending strength value increases more obviously when the impact speed exceeds 0.5 m/s or higher.By increasing the impact velocity,higher tensile strain rate of glass specimens can be obtained because the load action time becomes shorter.The bending strength of the glass material increases with its tensile strain rate,and when the tensile strain rate is between 0 and 2 s^(-1),the bending strength of the glass specimen grows more obviously with the strain rate,indicating that the glass bending strength is particularly sensitive to the tensile strain rate in this interval.As the strain rate increases,the number of cracks formed after glass breakage increases significantly,thus requiring more energy to drive the crack formation and expansion,and showing the strain rate effect of bending strength at the macroscopic level.The results of the study can provide a reference for the load bearing and structural design of glass materials under dynamic loading. 展开更多
关键词 glass materials strong dynamic impact bending strength strain rate effect dynamic enhancement factor
下载PDF
Effect of Health Management in Raising Awareness Rate of Disease Prevention and Treatment in Patients with Prehypertension
3
作者 Jing Huang 《Journal of Biosciences and Medicines》 2024年第2期236-243,共8页
Objective: To analyze the effect of health management on improving the awareness rate of disease prevention and treatment in patients with prehypertension, so as to provide guidance for clinical management of patients... Objective: To analyze the effect of health management on improving the awareness rate of disease prevention and treatment in patients with prehypertension, so as to provide guidance for clinical management of patients with prehypertension. Methods: 108 patients diagnosed with prehypertension in our hospital were divided into a control group and an experimental group. The control group was not given management measures, while the experimental group was given health management. The incidence of hypertension and cognition level of hypertension knowledge were compared between the two groups after management. Results: The incidence of hypertension in the experimental group was 7.41% lower than that in the control group 29.63%. The cognitive level of hypertension in the patients (66.54 ± 1.25) was significantly higher than that in the patients without health management (41.45 ± 2.45), and P < 0.05;Conclusion: For patients with prehypertension, the implementation of health management is helpful to improve their cognition of hypertension, master related prevention knowledge, and reduce the incidence of hypertension. 展开更多
关键词 Effect of Health Management in Raising Awareness rate of Disease Prevention and Treatment in Patients with Prehypertension
下载PDF
Proposal for a Tax Rate Swap to Shield Against the Gap Between Statutory and Effective Tax Rates-A Boost for Entrepreneurship and a Motive for New Investments
4
作者 Nicholas Belesis Nansy Karali Christina Heliotis 《Management Studies》 2021年第2期137-152,共16页
This paper focuses on a common problem for entrepreneurs and investors:the uncertainty around the actual tax rate,which is the percent of net income that a corporation pays in taxes.This uncertainty results from a dif... This paper focuses on a common problem for entrepreneurs and investors:the uncertainty around the actual tax rate,which is the percent of net income that a corporation pays in taxes.This uncertainty results from a difference(i.e.,a gap)between the statutory and the effective tax rate,which is the actual tax rate.This gap results from the legal framework which provides that certain types of incomes and expenses are not considered income.This gap causes significant uncertainty and may hinder entrepreneurship.This paper studies this gap in seven OECD countries(Austria,Canada,France,Germany,Italy,UK,and USA)and Brazil.We selected the 10 top-listed companies of each country and calculated the gaps for the period 2016-2019.Our findings proved that these gaps are unstable and may differ between companies of the same country and between countries.In addition,gaps of specific companies may change over time.The key outcome of this paper is the proposal of a new derivative tax rate swap.Using this derivative,governments will be able to eliminate the gap of specific companies,attract new investment,and increase entrepreneurship. 展开更多
关键词 tax rate swap corporate taxes statutory tax rate effective tax rate INVESTMENTS ENTREPRENEURSHIP
下载PDF
Laser-assisted Simulation of Dose Rate Effects of Wide Band Gap Semiconductor Devices
5
作者 TANG Ge XIAO Yao +3 位作者 SUN Peng LIU Jingrui ZHANG Fuwang LI Mo 《原子能科学技术》 EI CAS CSCD 北大核心 2023年第12期2314-2325,共12页
Laser-assisted simulation technique has played a crucial role in the investigation of dose rate effects of silicon-based devices and integrated circuits,due to its exceptional advantages in terms of flexibility,safety... Laser-assisted simulation technique has played a crucial role in the investigation of dose rate effects of silicon-based devices and integrated circuits,due to its exceptional advantages in terms of flexibility,safety,convenience,and precision.In recent years,wide band gap materials,known for their strong bonding and high ionization energy,have gained increasing attention from researchers and hold significant promise for extensive applications in specialized environments.Consequently,there is a growing need for comprehensive research on the dose rate effects of wide band gap materials.In response to this need,the use of laser-assisted simulation technology has emerged as a promising approach,offering an effective means to assess the efficacy of investigating these materials and devices.This paper focused on investigating the feasibility of laser-assisted simulation to study the dose rate effects of wide band gap semiconductor devices.Theoretical conversion factors for laser-assisted simulation of dose rate effects of GaN-based and SiC-based devices were been provided.Moreover,to validate the accuracy of the conversion factors,pulsed laser and dose rate experiments were conducted on GaN-based and SiC-based PIN diodes.The results demonstrate that pulsed laser radiation andγ-ray radiation can produce highly similar photocurrent responses in GaN-based and SiC-based PIN diodes,with correlation coefficients of 0.98 and 0.974,respectively.This finding reaffirms the effectiveness of laser-assisted simulation technology,making it a valuable complement in studying the dose rate effects of wide band gap semiconductor devices. 展开更多
关键词 laser-assisted simulation dose rate effect wide band gap semiconductor conversion factor
下载PDF
Covert Communication in Integrated High Altitude Platform Station Terrestrial Networks
6
作者 Zeke Wu Kefeng Guo +1 位作者 Rui Liu Shibin Zhu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第4期583-598,共16页
In recent years,Internet of Things(IoT)technology has emerged and gradually sprung up.As the needs of largescale IoT applications cannot be satisfied by the fifth generation(5G)network,wireless communication network n... In recent years,Internet of Things(IoT)technology has emerged and gradually sprung up.As the needs of largescale IoT applications cannot be satisfied by the fifth generation(5G)network,wireless communication network needs to be developed into the sixth generation(6G)network.However,with the increasingly prominent security problems of wireless communication networks such as 6G,covert communication has been recognized as one of the most promising solutions.Covert communication can realize the transmission of hidden information between both sides of communication to a certain extent,which makes the transmission content and transmission behavior challenging to be detected by noncooperative eavesdroppers.In addition,the integrated high altitude platform station(HAPS)terrestrial network is considered a promising development direction because of its flexibility and scalability.Based on the above facts,this article investigates the covert communication in an integrated HAPS terrestrial network,where a constant power auxiliary node is utilized to send artificial noise(AN)to realize the covert communication.Specifically,the covert constraint relationship between the transmitting and auxiliary nodes is derived.Moreover,the closed-form expressions of outage probability(OP)and effective covert communication rate are obtained.Finally,numerical results are provided to verify our analysis and reveal the impacts of critical parameters on the system performance. 展开更多
关键词 Covert communication the integrated HAPS terrestrial network constant power auxiliary node artificial noise(AN) effective covert communication rate
下载PDF
Testification on Effectiveness of Average or Weight-added Internal Rate of Return
7
作者 Xiaoshui Yu Guojie Zhao 《Chinese Business Review》 2006年第1期60-63,共4页
It seems that an effective way of how to make the right choice of Various investment projects is based on the theory of average internal income rate, or the theory of weight-added internal income rate. With several ex... It seems that an effective way of how to make the right choice of Various investment projects is based on the theory of average internal income rate, or the theory of weight-added internal income rate. With several examples of numerical value, this paper proves that this method is not as effective as expected, but indirectly testifies that only with the principle of maximization of NPV that independent projects can be the best combination of projects with limited investment that is achieved. 展开更多
关键词 average internal income rate weight-added internal income rate combination of independent projects testification of effectiveness
下载PDF
Risk factors for recurrence of common bile duct stones after surgical treatment and effect of ursodeoxycholic acid intervention
8
作者 Wei-Hong Yuan Zheng Zhang +2 位作者 Qi Pan Bo-Neng Mao Tao Yuan 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第1期103-112,共10页
BACKGROUND Endoscopic retrograde cholangiopancreatography(ERCP)is an accurate diagnostic method for choledocholithiasis and treatment option for stone removal.Additionally,ursodeoxycholic acid(UDCA)can dissolve choles... BACKGROUND Endoscopic retrograde cholangiopancreatography(ERCP)is an accurate diagnostic method for choledocholithiasis and treatment option for stone removal.Additionally,ursodeoxycholic acid(UDCA)can dissolve cholesterol stones and prevent their development and reappearance by lowering the cholesterol concen-tration in bile.Despite these treatment options,there are still patients who experience stone recurrence.The clinical data of 100 patients with choledochal stones who were hospitalized at the Yixing People’s Hospital and underwent ERCP for successful stone extraction between June 2020 and December 2022 were retrospectively collected.According to the post-ERCP treatment plan,100 patients were classified into UDCA(n=47)and control(n=53)groups.We aimed to assess the clinical efficacy and rate of relapse in the two patient populations.We then collected information(basic demographic data,clinical characteristics,and serum biochemical indicators)and determined the factors contributing to relapse using logistic regression analysis.Our secondary goal was to determine the effects of UDCA on liver function after ERCP.Compared to the control group,the UDCA group demonstrated a higher clinical effectiveness rate of 92.45%vs 78.72%(P<0.05).No significant differences were observed in liver function indices,including total bilirubin,direct bilirubin,gamma-glutamyl transpeptidase,alanine aminotransferase,alkaline phosphatase,and aspartate aminotransferase,between the two groups before treatment.After treatment,all liver function indices were significantly reduced.Comparing the control vs UDCA groups,the UDCA group exhibited significantly lower levels of all indices(55.39±6.53 vs 77.31±8.52,32.10±4.62 vs 45.39±5.69,142.32±14.21 vs 189.63±16.87,112.52±14.25 vs 149.36±15.36,122.61±16.00 vs 171.33±22.09,96.98±10.44 vs 121.35±11.57,respectively,all P<0.05).The stone recurrence rate was lower in the UDCA group(13.21%)in contrast with the control group(44.68%).Periampullary diverticula(OR:6.00,95%CI:1.69-21.30),maximum stone diameter(OR:1.69,95%CI:1.01-2.85),stone quantity>3(OR:4.23,95%CI:1.17-15.26),and positive bile culture(OR:7.61,95%CI:2.07-27.91)were independent factors that influenced the relapse of common bile duct stones after ERCP(P<0.05).Furthermore,postoperative UDCA was identified as a preventive factor(OR:0.07;95%CI:0.08-0.09).CONCLUSION The intervention effect of UDCA after ERCP for common bile duct stones is adequate,providing new research directions and references for the prevention and treatment of stone recurrence. 展开更多
关键词 Endoscopic retrograde cholangiopancreatography RECURRENCE Ursodeoxycholic acid Common bile duct stones Clinical effective rate Risk factors
下载PDF
Evaluation of the Effect and Efficiency of Ear Tip Bloodletting Combined with Xianfang Huoming Yin in the Treatment of Early-Stage Wheals
9
作者 Ying Pang 《Journal of Clinical and Nursing Research》 2024年第2期86-91,共6页
Objective:To evaluate the effect and efficiency of ear tip bloodletting combined with Xianfang Huoming Yin(XFH)in the treatment of early-stage wheals.Methods:70 patients with early-stage wheals admitted from September... Objective:To evaluate the effect and efficiency of ear tip bloodletting combined with Xianfang Huoming Yin(XFH)in the treatment of early-stage wheals.Methods:70 patients with early-stage wheals admitted from September 2020 to September 2022 were divided into two groups by randomized numerical table method,with 35 cases/group.Both groups received conventional treatment,the control group combined with XFH,and the observation group combined with ear tip bloodletting therapy and XFH.Conscious symptom scores,ocular indexes,therapeutic effects,and sleep quality between the two groups were compared.Results:After the treatment,the patients in the observation group had lower self-awareness symptom scores and sleep quality scores as compared to those in the control group;the diameter of the mass in the observation group was smaller than that of the control group after treatment;the average tear film rupture time and the time taken for the first non-contact tear film to rupture were longer in the observation group than those in the control group;the total effective rate of the treatment in the observation group was higher than that of the control group(P<0.05).Conclusion:Ear tip bloodletting combined with XFH was ideal for the treatment of early-stage wheals and has a high effective rate. 展开更多
关键词 Early stage of wheal Ear tip bloodletting Xianfang huoming yin effective rate
下载PDF
Strain-rate effect on initial crush stress of irregular honeycomb under dynamic loading and its deformation mechanism 被引量:4
10
作者 Peng Wang Zhijun Zheng +1 位作者 Shenfei Liao Jilin Yu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2018年第1期117-129,共13页
The seemingly contradictory understandings of the initial crush stress of cellular materials under dynamic loadings exist in the literature, and a comprehensive analysis of this issue is carried out with using direct ... The seemingly contradictory understandings of the initial crush stress of cellular materials under dynamic loadings exist in the literature, and a comprehensive analysis of this issue is carried out with using direct information of local stress and strain. Local stress/strain calculation methods are applied to determine the initial crush stresses and the strain rates at initial crush from a cell-based finite element model of irregular honeycomb under dynamic loadings. The initial crush stress under constant-velocity compression is identical to the quasi-static one, but less than the one under direct impact, i.e. the initial crush stresses under different dynamic loadings could be very different even though there is no strain-rate effect of matrix material. A power-law relation between the initial crush stress and the strain rate is explored to describe the strain-rate effect on the initial crush stress of irregular honeycomb when the local strain rate exceeds a critical value, below which there is no strain-rate effect of irregular honeycomb. Deformation mechanisms of the initial crush behavior under dynamic loadings are also explored.The deformation modes of the initial crush region in the front of plastic compaction wave are different under different dynamic loadings. 展开更多
关键词 Cellular material Constant-velocity compression Direct impact Cross-sectional stress Initial crush stress Strain rate effect
下载PDF
Mechanical properties of deep sandstones under loading rate effect 被引量:4
11
作者 ZHANG Jun-wen DING Lu-jiang +2 位作者 SONG Zhi-xiang FANWen-bing WANG Shan-yong 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第6期1933-1944,共12页
The advance speed of the working face in coal mines can significantly affect the fluctuation frequency of abutment pressure in front of the coal body.Moreover,it has a certain correlation with the change of axial load... The advance speed of the working face in coal mines can significantly affect the fluctuation frequency of abutment pressure in front of the coal body.Moreover,it has a certain correlation with the change of axial loading rate in coal and rock mechanics test.Therefore,uniaxial compression tests under various loading rates of 0.05,0.1,0.15,0.25,0.5 MPa/s were conducted using 2000 kN triaxial testing machine and PCI-2 acoustic emission test system to study the loading rate effect on the mechanical properties of deep sandstones.The results show that 1)the peak strength and elastic modulus of the deep sandstone increase with the loading rate increasing;2)with the loading rate increasing,the deep sandstone transforms from plastic-elastic-plastic to plastic-elastic and moreover,the failure mode gradually transfers from type I to type III;3)With the loading rate increasing,the total input strain energy,elastic strain energy,and dissipated strain energy generally increase;4)the damage variable presents the evolution characteristics of inverted“S”shape with time,and with the loading rate increasing,the damage degree of the deep sandstone is aggravated.The conclusion obtained can provide the theoretical basis for the stability control of the surrounding rock in deep engineering. 展开更多
关键词 loading rate effect failure mode energy evolution damage evolution mechanical properties deep sandstone
下载PDF
Model Building of the Initial Crown Effect Rate in 4-High Mill 被引量:2
12
作者 Jianzhong XU, Dianyao GONG, Wencai ZHANG, Xianwen CHANG, Xianghua LIU and Guodong WANG State Key Laboratory of Rolling Technology and Automation, Northeastern University, PO. Box 105, Shenyang 110004, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第2期165-169,共5页
The code for calculating the crown effect rate of hot strip steel Was developed using the effect function method. The effect of the initial crown on the crown of the product in hot strip rolling was investigated. The ... The code for calculating the crown effect rate of hot strip steel Was developed using the effect function method. The effect of the initial crown on the crown of the product in hot strip rolling was investigated. The coefficients of a polynomial of degree six for calculating the base value of initial crown effect rate in 4-high mill were determined and the compensation factors of per unit width rolling force, bending force, work roll crown and draft on the initial crown effect rate were given. The difference between the calculation result by established model and theoretical value obtained by effect function method was 4.88 μm when the strip width was 1.85 m. 展开更多
关键词 4-high mill Effect function Hot rolling strip Effect rate
下载PDF
Dependence of flow strength and deformation mechanisms in common wrought and die cast magnesium alloys on orientation,strain rate and temperature 被引量:4
13
作者 S.Xu W.R.Tyson +6 位作者 R.Eagleson R.Zavadil Z.Liu P.-L.Mao C.-Y.Wang S.I.Hill A.A.Luo 《Journal of Magnesium and Alloys》 SCIE EI CAS 2013年第4期275-282,共8页
The controlling plastic deformation mechanisms(i.e.slip or twinning)and the structural crash performance of Mg alloys are strongly influenced by loading mode,texture and microstructure.This paper summarizes the main r... The controlling plastic deformation mechanisms(i.e.slip or twinning)and the structural crash performance of Mg alloys are strongly influenced by loading mode,texture and microstructure.This paper summarizes the main results from an experimental program to assess these effects for commercial Mg alloy extrusions(AM30 and AZ31),sheet(AZ31),and high pressure die castings(HPDC,AM50 and AM60).Uniaxial tensile and compressive tests were performed over a wide range of strain rate and temperature(i.e.0.00075–2800 s^(−1) and 100℃ to−150℃)using conventional servo-hydraulic and high-strain-rate universal test machines and a split-Hopkinson-bar(SHB)apparatus.In primarily-slip-dominant deformation,the true stress–strain curves showed approximate power-law behavior,and the effects of strain rate and temperature on yield strength could be approximately described by constitutive equations linearly dependent on the rate parameter,Tln(5.3×10^(7)/ɛ˙)where T is test temperature in Kelvin andɛ˙is strain rate in s^(−1).In primarily-twin-dominant deformation,the effects of strain rate and temperature on yield and initial flow stress were negligible or small from quasi-static to 2800 s^(−1) owing to the athermal characteristics of mechanical twinning;the effects may become more pronounced with exhaustion of twinning and increasing proportion of slip. 展开更多
关键词 Constitutive equation Effects of strain rate and temperature Effects of orientation CRASHWORTHINESS Magnesium alloy
下载PDF
Numerical Derivation of Strain Rate Effects on Material Properties of Masonry with Solid Clay Bricks 被引量:4
14
作者 WEI Xueying HAO Hong 《Transactions of Tianjin University》 EI CAS 2006年第B09期147-151,共5页
In this paper, numerical method is used als. A typical unit of masonry is selected to serve merical model of RVE is established with detailed to study the strain rate effect on masonry materias a representative volume... In this paper, numerical method is used als. A typical unit of masonry is selected to serve merical model of RVE is established with detailed to study the strain rate effect on masonry materias a representative volume element (RVE). Nudistinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor (DIF) of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results. 展开更多
关键词 masonry structure strain rate effects dynamic increase factor (DIF) elastic modulus ultimate strength
下载PDF
Model Building of Backup Roller Diameter Effect Rate in 4-High Mill 被引量:1
15
作者 JianzhongXU DianyaoGONG +2 位作者 XianghuaLIU GuodongWANG XiaolinZHAO 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2004年第4期454-456,共3页
Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method. Regularity of backup roller diameter effect rate was studied systematically using the software. T... Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method. Regularity of backup roller diameter effect rate was studied systematically using the software. The results show that backup roller diameter effect rates decrease versus the increase of strip width, increase significantly versus the increase of backup roller diameter and obscurely increase versus the increase of reduction. The difference between backup roller diameter effect rate and it is reference value increases versus strip width increasing. When backup rollers diameter is set to be 1.64 m and strip width is 1.85 m, the error of strip profile calculated using the model of backup roller diameter effect rate reference value will be 3.55μm. Based on the results, reference values of roller diameter effect rate and six power polynomial fitting coefficients of modification coefficients were determined considering coherent parameters. The high precision model of backup roller diameter effect rate was established. When the model is used to predict strip profile, the accuracy is less than 5.0 μm. 展开更多
关键词 4-high mill Influence coefficient method Strip profile Hot rolling Backup roller diameter Effect rate
下载PDF
Effects of Temperature and Strain Rate on Dynamic Properties of Concrete 被引量:1
16
作者 贾彬 陶俊林 +2 位作者 李正良 王汝恒 张誉 《Transactions of Tianjin University》 EI CAS 2008年第B10期511-513,共3页
To study the dynamic properties of the concrete subjected to impulsive loading, stress-time curves of concrete in different velocities were measured using split Hopkinson pressure bar (SHPB).Effects of temperature and... To study the dynamic properties of the concrete subjected to impulsive loading, stress-time curves of concrete in different velocities were measured using split Hopkinson pressure bar (SHPB).Effects of temperature and strain rate on the dynamic yield strength and constitutive relation of the con-crete were analyzed. The dynamic mechanical properties of the reinforced concrete are subjected to high strain rates when it is at a relatively low temperature. But with temperature increasing, the temperature softening effect makes the strength of the concrete weaken and the impact toughness of the concrete is saliently relative to strain rate effect. So, strain rate effect, strain hardening and temperature softening work together on the dynamic mechanical capability of concrete and the relation between them is relatively complex. 展开更多
关键词 CONCRETE temperature effect strain rate effect SHPB
下载PDF
Modeling Strain Rate Effect for Heterogeneous Brittle Materials 被引量:1
17
作者 MA Guowei DONG Aiai LI Jianchun 《Transactions of Tianjin University》 EI CAS 2006年第B09期79-82,共4页
Rocks are heterogeneous from the point of dynamic failure behavior. Both the compressive and microstructure which is of significance to their tensile strength of rock-like materials is regarded different from the stat... Rocks are heterogeneous from the point of dynamic failure behavior. Both the compressive and microstructure which is of significance to their tensile strength of rock-like materials is regarded different from the static strength. The present study adopts smoothed particle hydrodynamics (SPH) which is a virtual particle based meshfree method to investigate strain rate effect for heterogeneous brittle materials. The SPH method is capable of simulating rock fracture, free of the mesh constraint of the traditional FEM and FDM models. A pressure dependent J-H constitutive model involving heterogeneity is employed in the numerical modeling. The results show the compressive strength increases with the increase of strain rate as well as the tensile strength, which is important to the engineering design. 展开更多
关键词 HETEROGENEOUS strain rate effect SPH method
下载PDF
Effect of Penetration Rates on the Piezocone Penetration Test in the Yellow River Delta Silt 被引量:1
18
作者 ZHANG Jiarui MENG Qingsheng +4 位作者 ZHANG Yan FENG Xiuli WEI Guanli SU Xiuting LIU Tao 《Journal of Ocean University of China》 SCIE CAS CSCD 2022年第2期361-374,共14页
Partial drainage often occurs during piezocone penetration testing on Yellow River Delta silt because of its intermediate physical and mechanical properties between those of sand and clay.Yet,there is no accurate unde... Partial drainage often occurs during piezocone penetration testing on Yellow River Delta silt because of its intermediate physical and mechanical properties between those of sand and clay.Yet,there is no accurate understanding for the range of penetra-tion rates to trigger the partial drainage of silt soils.In order to fully investigate cone penetration rate effects under partial drainage condi-tions,indoor 1 g penetration model tests and numerical simulations of cavity expansion at variable penetration rates were carried out on the Yellow River Delta silt.The boundary effect of the model tests and the variation of key parameters at the different cavity ex-pansion rates were analyzed.The 1 g penetration model test results and numerical simulations results consistently indicated that the penetration rate to trigger the partially drainage of typical silt varied at least three orders of magnitude.The numerical simulations also provide the reference values for the penetration resistance corresponding to zero dilation and zero viscosity at any given normalized penetration rate for silt in Yellow River Delta.These geotechnical properties can be used for the design of offshore platforms in Yel-low River Delta,and the understanding of cone penetration rate effects under the partially drained conditions would provide some technical support for geohazard evaluation of offshore platforms. 展开更多
关键词 Yellow River Delta silt cone penetration rate effects 1g model simulation numerical analysis
下载PDF
Rate efect and coupled evolution of atomic motions and potential landscapes
19
作者 Pan Xiao Jun Wang +3 位作者 Rong Yang Fu-Jiu Ke Meng-Fen Xia Yi-Long Bai 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2013年第5期676-681,共6页
Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of at... Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of atomic system is closely related to the coupled evolution of atomic motions and potential landscapes. Accordingly, it becomes possible to develop a new algorithm of molecular simulation, which could properly and efficiently demonstrate strain rate effect under a wide range of loading rates and unveil the mecha- nisms underlying the strain rate effects. 展开更多
关键词 Strain rate effect Atomic motions - Potential landscape Molecular simulation
下载PDF
Study on the Dynamic Behavior of Tungsten Alloy at Strain Rates up to 5 000 s^(-1)
20
作者 张宝■ 郑玉六 武海军 《Journal of Beijing Institute of Technology》 EI CAS 2004年第3期270-273,共4页
The dynamic stress-strain curves of 93% tungsten (W) alloy in the forged state at strain rates up to (5 000 s^(-1)) and in the temperature range from 223 K to 473 K were measured with the split Hopkinson pressure bar ... The dynamic stress-strain curves of 93% tungsten (W) alloy in the forged state at strain rates up to (5 000 s^(-1)) and in the temperature range from 223 K to 473 K were measured with the split Hopkinson pressure bar (SHPB) technique. Based on the above experimental data a dynamic constitutive equation considering the effects of strain rate, temperature and the special microstructure of such a kind of W-alloy was proposed. The numerical simulation for the experimental process with this constitutive equation was also carried out, the results show that the constitutive relationship constructed in this paper is very satisfactory for representing the dynamic responsive behavior of material.. 展开更多
关键词 tungsten alloy constitutive relationship high strain rate effect dynamic behavior of material
下载PDF
上一页 1 2 5 下一页 到第
使用帮助 返回顶部