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Radiological characterization of building materials used in Malaysia and assessment of external and internal doses 预览
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作者 Shittu Abdullahi Aznan Fazli Ismail Supian Samat 《核技术:英文版》 SCIE CAS CSCD 2019年第3期82-96,共15页
In this study, the activity concentrations of ^226Ra,^232Th,^222Rn, and 40K, emanation fractions (P), equilibrium equivalent concentration (EEC), and mass exhalation rates (Em) of radon released from building material... In this study, the activity concentrations of ^226Ra,^232Th,^222Rn, and 40K, emanation fractions (P), equilibrium equivalent concentration (EEC), and mass exhalation rates (Em) of radon released from building materials used in Malaysia were studied using gamma-ray spectrometer with HPGe detector. Radiological parameters [activity concentration index (ACI), indoor air-absorbed dose rate (Din), annual effective dose (AEDin) from external and internal (ERn), soft tissues (HST) and lung (HL), and effective dose equivalent (Heff)] were estimated to evaluate radiological hazards due to the use of these building materials: sand, cement, gravel, bricks, tiles, fly ash, white cement, and ceramic raw materials. The measured P, EEC, and Em vary from 10 to 30%, 0.9 to 22 Bq m-3, and 33 to 674 mBq h^-1 kg^-1, respectively, while the calculated ACI and AEDin vary from 0.1 ± 0.01 to 2.1 ± 0.1 and 0.1 ± 0.01 to 2.4 ± 0.6 mSv y^-1, respectively. On the other hand, the internal annual effective dose ranges from 0.1 to 1.4 mSv y^-1. The estimated radiological risk parameters were below the recommended maximum values, and radiological hazards associated with building materials under investigation are therefore negligible. 展开更多
关键词 Indoor radon EMANATION fraction Equilibrium EQUIVALENT concentration Mass EXHALATION rate Annual EFFECTIVE DOSE EFFECTIVE DOSE EQUIVALENT
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The challenges of precision radiotherapy technology to the traditional theory of radiobiology
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作者 Ma Shumei Liang Zhenzhen +3 位作者 Chen Qiao Liu Rui Guo Yutian Liu Xiaodong 《中华放射医学与防护杂志》 CAS CSCD 北大核心 2019年第8期563-571,共9页
With the development of modern computing technology and medical physics,radiotherapy has made great progress.The theoretical basis of radiobiology seems to lag behind the clinical application of radiotherapy,which ham... With the development of modern computing technology and medical physics,radiotherapy has made great progress.The theoretical basis of radiobiology seems to lag behind the clinical application of radiotherapy,which hampers the further improvement of treatment efficacy and the optimization of treatment modality.In this paper,some emerging challenges of precision radiotherapy technology to the traditional theory of radiobiology,such as radiosensitivity,dose-response curve and survival curve,linear-quadratic model,4Rs theory,as well as the interaction between cancer and microenvironment,radiation-induced second primary cancers(RISPC),will be discussed.The interplay between precision radiotherapy and traditional radiobiology theories will be addressed with the aim to potentially solve some of the challenging problems. 展开更多
关键词 PRECISION RADIOTHERAPY RADIOBIOLOGY Linear-quadratic model Biological equivalent DOSE RADIOSENSITIVITY
Microstructure and finite element analysis of hot continuous rolling of doped tungsten rod 预览
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作者 Zheng-jie Shao Hai-po Liu +5 位作者 Xiao-chun He Bing Zhou Yang Li Shang-zhou Zhang Meng-jin Li Shu-jun Li 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第3期369-376,共8页
The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element (FE) method. After the continuous rolling, the g... The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element (FE) method. After the continuous rolling, the grains of the tungsten rod were refined, and the microhardness was improved;however, a ring region of abnormal grain growth was present at a distance of about 3/5R (R is the radius of the rod) from the center of the cross section. FE modeling results showed that the equivalent residual strains were minimum around the region of abnormal grain growth;this was due to the release of strain energy by severe plastic deformation, leading a situation where the migration force of grain boundaries was higher than the pinning force of potassium bubbles. By decreasing the initial rolling temperature and rolling speeds, the inhomogeneity of the equivalent residual stain decreased, improving the microstructure uniformity of the doped tungsten. 展开更多
关键词 DOPED TUNGSTEN continuous ROLLING MICROSTRUCTURE finite element analysis EQUIVALENT RESIDUAL strain
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An Optimization Algorithm of Circular Interpolation Aiming at Pointby- Point Comparison Method 预览
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作者 Xiaochun Shu Xiaoling Huang +2 位作者 Qianbao Cheng Yan Li Liyong Hu 《现代电子技术(英文)》 2019年第1期39-44,共6页
Interpolation technology is the core technology of numerical control technology, and the requirements for curve processing in numerical control machine tools are getting higher and higher. According to the current dev... Interpolation technology is the core technology of numerical control technology, and the requirements for curve processing in numerical control machine tools are getting higher and higher. According to the current development of numerical control machining, the optimization of the interpolation technology for arcs is proposed,[1] and the improvement is proposed in the original feeding mode which not only improves the calculation speed of the interpolation, but also improves the processing efflciency. In addition, the improved algorithm can reduce the machining error so that the error can be reduced to within the range of 0.5 pulses equivalent. 展开更多
关键词 INTERPOLATION CIRCULAR INTERPOLATION PULSE EQUIVALENT
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Assessment of physical activity status among pregnant women in southwestern China 预览
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作者 Ya-Nan Yin Yan Huang +1 位作者 Xing-Hui Liu Bi-Ru Luo 《护理前沿(英文)》 CAS 2019年第2期135-141,共7页
Objective: To assess the patterns and intensities of physical activity among pregnant women in southwestern China, which help us create a fitness regimen based on the 2002 American College of Obstetricians and Gynecol... Objective: To assess the patterns and intensities of physical activity among pregnant women in southwestern China, which help us create a fitness regimen based on the 2002 American College of Obstetricians and Gynecologists (ACOG) guidelines for exercise during pregnancy. Methods: A cross-sectional study was performed to recruit pregnant women at a prenatal checking visit clinic with the self-administered Chinese version of Pregnancy Physical Activity Questionnaire (PPAQ). Results: A total of 1179 Chinese pregnant women were enrolled, of whom 92.60% were classified as not meeting the ACOG guidelines. By intensity, 47.36% of the score was attributed to light-intensity activities (1.5 to <3.0 metabolic equivalent [MET]) in the first trimester;the other 2 trimesters were similar. By patterns, about 45.15% of the score was attributed to inactivity. More than 82.35% of enrolled pregnant women regarded slowly walking as the most common type of exercise during pregnancy. Conclusions: This study represents a group of Chinese women who maintained an inactive lifestyle, including low-intensity activities and unitary type of exercises during their pregnancy. Health-care providers are advised to provide appropriate physical activity guidelines to pregnant women. Development of MET-hours/week recommendations is warranted to promote greater physical activity during pregnancy. 展开更多
关键词 physical activity CROSS-SECTIONAL studies PREGNANCY inactive LIFESTYLE METABOLIC equivalent MET
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Equivalent model of close-packed film cooling holes in nickel-based single crystal cooled blade based on crystallographic theory
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作者 Yamin ZHANG Zhixun WEN +1 位作者 Haiqing PEI Zhufeng YUE 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第4期839-850,共12页
The mechanical properties of nickel-based single crystal thin-walled plate with close-packed film cooling holes were studied based on the equivalent solid material concept. The effective plastic parameters inversion m... The mechanical properties of nickel-based single crystal thin-walled plate with close-packed film cooling holes were studied based on the equivalent solid material concept. The effective plastic parameters inversion method based on crystallographic theory were proposed. A simplification method for close-packed film cooling hole plates with square and triangular penetration patterns was presented. A large number of finite element analysis results covering different ligament efficiencies and penetration patterns were provided to verify the feasibility of the plastic equivalent principle and simplification method. The results show that the stress–strain curve and resolved shear stresses of simplification models are in consistence with the plate models with close-packed film cooling holes. The equivalent errors of yield strength are all within the error band and the values of equivalent errors are all less than 10%. In addition, the equivalent errors of the positions where maximum resolved shear stress occurs are all less than 15°, indicating the accuracy of plastic equivalent model and simplification method. 展开更多
关键词 Close-packed ?lm COOLING HOLES Crystallographic theory EQUIVALENT Simpli?cation Single crystal
Prediction Model of Coal Reservoir Pressure and its Implication for the Law of Coal Reservoir Depressurization 预览
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作者 YAN Xinlu ZHANG Songhang +5 位作者 TANG Shuheng LI Zhongcheng WANG Kaifeng YI Yongxiang DANG Feng HU Qiuping 《地质学报:英文版》 SCIE CAS CSCD 2019年第3期692-703,共12页
The main methods of coalbed methane(CBM)development are drainage and depressurization,and a precise prediction of coal reservoir pressure is thus crucial for the evaluation of reservoir potentials and the formulation ... The main methods of coalbed methane(CBM)development are drainage and depressurization,and a precise prediction of coal reservoir pressure is thus crucial for the evaluation of reservoir potentials and the formulation of reasonable development plans.This work established a new reservoir pressure prediction model based on the material balance equation(MBE)of coal reservoir,which considers the self-regulating effects of coal reservoirs and the dynamic change of equivalent drainage area(EDA).According to the proposed model,the reservoir pressure can be predicted based on reservoir condition data and the actual production data of a single well.Compared with traditional reservoir pressure prediction models which regard EDA as a fixed value,the proposed model can better predict the average pressure of reservoirs.Moreover,orthogonal experiments were designed to evaluate the sensitivity of reservoir parameters on the reservoir pressure prediction results of this proposed model.The results show that the saturation of irreducible water is the most sensitive parameter,followed by Langmuir volume and reservoir porosity,and Langmuir pressure is the least sensitive parameter.In addition,the pressure drop of reservoirs is negatively correlated with the saturation of irreducible water and the Langmuir volume,while it is positively correlated with porosity.This work analyzed the reservoir pressure drop characteristics of the CBM wells in the Shizhuangnan Block of the Qinshui Basin,and the results show that the CBM reservoir depressurization can be divided into three types,i.e.,rapidly drop type,medium-term stability type,and slowly drop type.The drainage features of wells were reasonably interpreted based on the comprehensive analysis of the reservoir depressurization type;the latter was coupled to the corresponding permeability dynamic change characteristics,eventually proving the applicability of the proposed model. 展开更多
关键词 coalbed METHANE PRESSURE PREDICTION EQUIVALENT drainage area influencing factors PRESSURE DROP types Qinshui Basin
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Rock burst risk evaluation based on equivalent surrounding rock strength 预览
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作者 Jinglin Wen Husheng Li +3 位作者 Fuxing Jiang Zhengxing Yu Haitao Ma Xiaolin Yang 《矿业科学技术学报:英文版》 CSCD 2019年第4期571-576,共6页
On-site investigations consistently show that the rock burst inherent to coal seams varies greatly with coal seam thickness.In this study,impact factors related to coal seam thickness and surrounding rock strength wer... On-site investigations consistently show that the rock burst inherent to coal seams varies greatly with coal seam thickness.In this study,impact factors related to coal seam thickness and surrounding rock strength were analyzed and a corresponding rock burst risk assessment method was constructed.The model reflects the influence of coal seam thickness on the stress distribution of surrounding rock at the roadway.Based on the roadway excavation range,a stress distribution model of surrounding roadway rock is established and the influence of coal seam thickness on rock burst risk is analyzed accordingly.The proposed rock burst risk assessment method is based on the equivalent surrounding rock strength and coal seam bursting liability.The proposed method was tested in a 3500 mining area to find that it yields rock burst risk assessment results as per coal seam thickness that are in accordance with real-world conditions.The results presented here suggest that coal seam thickness is a crucial factor in effective rock burst risk assessment. 展开更多
关键词 Mining engineering Coal seam thickness Rock burst risk Equivalent surrounding rock strength Bursting liability
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Equivalent electromagnetic parameters for microwave metamaterial absorber using a new symmetry model
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作者 张峻铭 何东霖 +4 位作者 王国武 王鹏 乔亮 王涛 李发伸 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期350-354,共5页
Transmission line theory uses the complex nature of permeability and permittivity of a conventional magnetic absorber to evaluate its absorption properties and mechanism.However,because there is no method to obtain th... Transmission line theory uses the complex nature of permeability and permittivity of a conventional magnetic absorber to evaluate its absorption properties and mechanism.However,because there is no method to obtain the electromagnetic parameters of a metamaterial-absorber integrated layer (composed of a medium layer and a periodic metal array),this theory is seldom used to study the absorption properties of the metamaterial absorber.We propose a symmetry model to achieve an equivalent complex permittivity and permeability model for the integrated layer,which can be combined with the transmission line theory to calculate metamaterial absorption properties.The calculation results derived from both the transmission line theory and the high-frequency structure simulator are in good agreement.This method will be beneficial in practical investigations of the absorption mechanism of a metamaterial absorber. 展开更多
关键词 METAMATERIAL ABSORBER EQUIVALENT ELECTROMAGNETIC parameters transmission line theory
Regularized focusing inversion for large-scale gravity data based on GPU parallel computing 预览
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作者 WANG Haoran DING Yidan +1 位作者 LI Feida LI Jing 《世界地质:英文版》 2019年第3期179-187,共9页
Processing large-scale 3-D gravity data is an important topic in geophysics field. Many existing inversion methods lack the competence of processing massive data and practical application capacity. This study proposes... Processing large-scale 3-D gravity data is an important topic in geophysics field. Many existing inversion methods lack the competence of processing massive data and practical application capacity. This study proposes the application of GPU parallel processing technology to the focusing inversion method, aiming at improving the inversion accuracy while speeding up calculation and reducing the memory consumption, thus obtaining the fast and reliable inversion results for large complex model. In this paper, equivalent storage of geometric trellis is used to calculate the sensitivity matrix, and the inversion is based on GPU parallel computing technology. The parallel computing program that is optimized by reducing data transfer, access restrictions and instruction restrictions as well as latency hiding greatly reduces the memory usage, speeds up the calculation, and makes the fast inversion of large models possible. By comparing and analyzing the computing speed of traditional single thread CPU method and CUDA-based GPU parallel technology, the excellent acceleration performance of GPU parallel computing is verified, which provides ideas for practical application of some theoretical inversion methods restricted by computing speed and computer memory. The model test verifies that the focusing inversion method can overcome the problem of severe skin effect and ambiguity of geological body boundary. Moreover, the increase of the model cells and inversion data can more clearly depict the boundary position of the abnormal body and delineate its specific shape. 展开更多
关键词 LARGE-SCALE gravity data GPU parallel computing CUDA equivalent geometric TRELLIS FOCUSING INVERSION
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Methodology to Evaluate Fatigue Damage of High-Speed Train Welded Bogie Frames Based on On-Track Dynamic Stress Test Data
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作者 Guangxue Yang Meng Wang +1 位作者 Qiang Li Ran Ding 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2019年第3期181-188,共8页
The current method of estimating the fatigue life of railway structures is to calculating the equivalent stress amplitude based on the measured stress data. However, the random of the measured data is not considered. ... The current method of estimating the fatigue life of railway structures is to calculating the equivalent stress amplitude based on the measured stress data. However, the random of the measured data is not considered. In this paper, a new method was established to compute the equivalent stress amplitude to evaluate the fatigue damage based on the measurable randomness, since the equivalent stress is the key parameter for assessment of structure fatigue life and load derivation. The equivalent stress amplitude of a high-speed train welded bogie frame was found to obey normal distribution under uniform operation route that verified by on-track dynamic stress data, and the proposed model is, in effect, an improved version of the mathematical model used to calculate the equivalent stress amplitude. The data of a long-term, on-track dynamic stress test program was analyzed to find that the normal distribution parameters of equivalent stress amplitude values differ across different operation route. Thus, the fatigue damage of the high-speed train welded bogie frame can be evaluated by the proposed method if the running schedule of the train is known a priori. The results also showed that the equivalent stress amplitude of the region connected to the power system is more random than in other regions of the bogie frame. 展开更多
关键词 Fatigue damage evaluation Equivalent STRESS AMPLITUDE On-track dynamic STRESS test Welded BOGIE frame of high-speed train
Low-intensity walking as mild medication for pressure control in prehypertensive and hypertensive subjects: how far shall we wander?
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作者 Qin Lu Sheng-ming Wang +14 位作者 Yi-xiao Liu Hong Chen Rui Zhang Wen-hui Zhang Yuan-yuan Zou Jia-wei Zhou Xin-yi Guo Ying Zhang Teng-Li Huang Yu-hang Liu Si-qi Zhang Kyosuke Yamanishi Hiromichi Yamanishi Hideaki Higashino Haruki Okamura 《中国药理学报:英文版》 SCIE CAS CSCD 2019年第8期1119-1126,共8页
Successful prevention and treatment of hypertension depend on the appropriate combination of antihypertensive drug therapy and nondrug lifestyle modi?cation. While most hypertension guidelines recommend moderate- to h... Successful prevention and treatment of hypertension depend on the appropriate combination of antihypertensive drug therapy and nondrug lifestyle modi?cation. While most hypertension guidelines recommend moderate- to high-intensity exercise, we decided to explore a mild yet effective type of exercise to add to hypertension management, especially in populations with complications or frailty. After comparing the short-term cardiovascular effects of low-speed walking versus high-speed walking for 3 kilometers (km)(3 km/h versus 6 km/h) in young, healthy volunteers, we delivered low-speed walking (low-intensity walking, 2.5 metabolic equivalents of task, METs) as exercise therapy in 42 prehypertensive and 43 hypertensive subjects. We found that one session of 3 km low-intensity walking exerted a transient pressure-lowering effect as well as a mild negative chronotropic effect on heart rate in both the prehypertensive and hypertensive subjects;these short-term bene?ts on blood pressure and heart rate were accompanied by a brief increase in urine β-endorphin output. Then we prescribed regular low-intensity walking with a target exercise dose (exercise volume) of 500–1000 METs·min/week (50–60 min/day and 5–7 times/week) in hypertensive subjects in addition to their daily activities. Regular low-intensity walking also showed mild but signi?cant blood pressure-lowering and heart rate-reducing effects in 7 hypertensive subjects within two months. It is hypothesized that regular low-intensity exercise of the necessary dose could be taken as a pragmatic and supplementary medication for hypertension management. 展开更多
关键词 hypertension PREHYPERTENSION exercise MEDICATION low-intensity WALKING metabolic equivalent of task blood pressure heart rate urine Β-ENDORPHIN
Negative refraction of deep water waves through water channel network 预览
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作者 Takahito Iida Masashi Kashiwagi 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第4期840-847,共8页
A design method of a negative refractive index for free surface water waves in deep water is presented. To obtain a condition of a negative index, an analogy between water waves in a water channel and electric waves i... A design method of a negative refractive index for free surface water waves in deep water is presented. To obtain a condition of a negative index, an analogy between water waves in a water channel and electric waves in an electric circuit is employed. An analytical solution of waves around a periodic array of rectangular columns is obtained by a circuit analysis. Attention is not focused on columns but a space among columns, and then the space is regarded as the water channel. Therefore, the circuit analysis can be applied to water waves. One channel is treated as a unit structure and a number of channels are periodically cascaded as a network. The negative refraction and backward waves by a network of the water channels are shown. Since the negative refraction might occur even around simple periodic structures, it is meaningful to understand wave phenomenon around offshore structures and develop innovative technology. 展开更多
关键词 NEGATIVE refractive index BACKWARD wave WATER channel NETWORK EQUIVALENT circuit deep WATER
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Linear stability theory with the equivalent spanwise wavenumber correction in 3D boundary layers 预览
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作者 Runjie SONG Shaolong ZHANG Jianxin LIU 《应用数学和力学:英文版》 SCIE EI CSCD 2019年第3期407-420,共14页
The prediction on small disturbance propagation in complex three-dimensional(3D)boundary layers is of great significance in transition prediction methodology,especially in the aircraft design.In this paper,the linear ... The prediction on small disturbance propagation in complex three-dimensional(3D)boundary layers is of great significance in transition prediction methodology,especially in the aircraft design.In this paper,the linear stability theory(LST)with the equivalent spanwise wavenumber correction(ESWC)is proposed in order to accurately predict the linear evolution of a disturbance in a kind of boundary layer flow with a vital variation in the spanwise direction.The LST with the ESWC takes not only the scale of the mean flow with the significant variation but also the wavenumber evolution of the disturbance itself.Compared with the conventional LST,the results obtained by the new method are in excellent agreement with those of the numerical simulations.The LST with the ESWC is an effective method on the prediction of the disturbance evolution in 3D boundary layers,which improves the prediction of the LST in the applications to complex 3D boundary layers greatly. 展开更多
关键词 three-dimensional(3D)boundary layer prediction of DISTURBANCE propagation EQUIVALENT spanwise WAVENUMBER LINEAR stability theory(LST) numerical simulation
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Experimental and numerical investigations of bonding interface behavior in stationary shoulder friction stir lap welding
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作者 Q.wen W.Y.Li +3 位作者 W.B.Wang F.F.Wang Y.J.Gao V.Patel 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第1期192-200,共9页
Stationary shoulder friction stir lap welding(SSFSLW) was employed to weld 2024 aluminum alloy. A coupled Eulerian-Lagrangian(CEL) model was developed to investigate the lap interface behavior during SSFSLW. Numerical... Stationary shoulder friction stir lap welding(SSFSLW) was employed to weld 2024 aluminum alloy. A coupled Eulerian-Lagrangian(CEL) model was developed to investigate the lap interface behavior during SSFSLW. Numerical results of material movement and equivalent plastic strain were in good agreement with the experimental work. With increasing welding speed, the distances from the hook tip to the top surface of the upper workpiece on the retreating side(RS) and the advancing side(AS) increase, while the distance between two wave-shaped alclads decreases. A symmetric interface bending is observed on the AS and the RS during plunging, while the interface bending on the AS is bigger than that on the RS during welding. The peak temperature of the interface on the AS is higher than that on the RS. The equivalent plastic strain gradually increases as the distance to the weld center decreases, and its peak value is obtained near the bottom of the weld. 展开更多
关键词 STATIONARY SHOULDER FRICTION STIR LAP welding Coupled Eulerian-Lagrangian Temperature field Material distribution EQUIVALENT plastic strain
考虑频率约束及风电机组调频的风电穿透功率极限计算
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作者 李世春 唐红艳 +3 位作者 邓长虹 刘道兵 舒征宇 钟浩 《电力系统自动化》 EI CSCD 北大核心 2019年第4期33-39,共7页
随着风电渗透率持续增加以及虚拟惯性/一次调频控制技术逐步推广应用,准确计算风电穿透功率极限对于确保电网安全稳定运行和指导风电并网规划建设具有重要意义。为此,文中定量表征了风电场虚拟惯性响应特性,并采用传递函数模型表示风电... 随着风电渗透率持续增加以及虚拟惯性/一次调频控制技术逐步推广应用,准确计算风电穿透功率极限对于确保电网安全稳定运行和指导风电并网规划建设具有重要意义。为此,文中定量表征了风电场虚拟惯性响应特性,并采用传递函数模型表示风电场一次调频响应特性,进而建立了包含风电场、同步发电机组调频控制的电网等值转子摇摆方程,用于描述电力系统频率响应特性。在此基础上,以电网稳态频率偏差约束和频率变化率约束为边界条件,提出了风电穿透功率极限的解析求解方法。最后,通过IEEE 14节点系统算例验证了所提方法的精确性和有效性。 展开更多
关键词 风力发电 风电穿透功率极限 虚拟惯性 一次调频 等值 频率稳定
关于自然数定义的商榷 预览
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作者 李高 常秀芳 《山西大同大学学报:自然科学版》 2019年第1期22-24,共3页
从数的萌芽到数的产生的发展过程,给出了自然数和零的概念,指出现行教材中自然数定义的不妥,给予修正。
关键词 自然数 等价 标准集合
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Determination of water equivalent ratio for some dosimetric materials in proton therapy using MNCPX simulation tool 预览
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作者 Reza Bagheri Alireza Khorrami Moghaddam +2 位作者 Bakhtiar Azadbakht Mahmoud Reza Akbari Seyed Pezhman Shirmardi 《核技术:英文版》 SCIE CAS CSCD 2019年第2期19-28,共10页
The water equivalent ratio(WER)was calculated for polypropylene(PP),paraffin,polyethylene(PE),polystyrene(PS),polymethyl methacrylate(PMMA),and polycarbonate materials with potential applications in dosimetry and medi... The water equivalent ratio(WER)was calculated for polypropylene(PP),paraffin,polyethylene(PE),polystyrene(PS),polymethyl methacrylate(PMMA),and polycarbonate materials with potential applications in dosimetry and medical physics.This was performed using the Monte Carlo simulation code,MCNPX,at different proton energies.The calculated WER values were compared with National Institute of Standards and Technology(NIST)data,available experimental and analytical results,as well as the FLUKA,SRIM,and SEICS codes.PP and PMMA were associated with the minimum and maximum WER values,respectively.Good agreement was observed between the MCNPX and NIST data.The biggest difference was 0.71%for PS at 150 MeV proton energy.In addition,a relatively large positive correlation between the WER values and the electron density of the dosimetric materials was observed.Finally,it was noted that PE presented the most analogous Depth Dose Characteristics to liquid water. 展开更多
关键词 WATER EQUIVALENT RATIO PROTON therapy Dosimetric MATERIALS MCNPX code
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亚甲蓝分光光度法测定水中阴离子表面活性剂的方法研究 预览
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作者 李超 《安徽农学通报》 2019年第17期122-123,共2页
亚甲基蓝分光光度法测定阴离子表面活性剂的国标方法操作复杂,不仅耗时长而且大量使用有机溶剂对实验人员身体损伤较大。该研究通过同步实验对比分析,结果表明:加入25mL亚甲蓝,一次性20mL三氯甲烷萃取,再使用洗涤的方法,其测定结果的精... 亚甲基蓝分光光度法测定阴离子表面活性剂的国标方法操作复杂,不仅耗时长而且大量使用有机溶剂对实验人员身体损伤较大。该研究通过同步实验对比分析,结果表明:加入25mL亚甲蓝,一次性20mL三氯甲烷萃取,再使用洗涤的方法,其测定结果的精密性和准确度等同于国标方法,且具有良好的可操作性、安全性和经济性。 展开更多
关键词 亚甲基蓝分光光度法 阴离子表面活性剂 对比分析 等同 国标方法
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Two-dimensional coupled vibration and equivalent circuit of longitudinal-longitudinal orthogonal composite vibration direction converter
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作者 XU Long ZHOU Jincheng +2 位作者 CHANG Yan LI Fengming LI Weidong 《声学学报:英文版》 CSCD 2019年第1期62-72,共11页
With the advantages of transmitting energy from multiple directions to one direction and transforming vibration from one source to multiple directions,the two-dimensional vibration direction converter has important ap... With the advantages of transmitting energy from multiple directions to one direction and transforming vibration from one source to multiple directions,the two-dimensional vibration direction converter has important applications in power ultrasonic technology.However,for the complexity of using the wave equation to design and analysis the two-dimensional vibration direction converter,a concise equivalent circuit for the converter is investigated.By introducing the two-dimensional mechanical coupling coefficient and the longitudinal force transform coef- ficient,and using the electromechanical analogy principle,the equivalent circuit and resonance frequency equation of the two-dimensional vibration direction converter vibrating in anti-phase and in-phase two-dimensional coupled vibration are deduced.The resonance frequencies of the vibration direction converters of two different materials are calculated by using the proposed frequency equation,which are in agreement with the results from the finite element method and the experimental test.It provides a concise method for the design and applications of such ultrasonic vibration system. 展开更多
关键词 TWO-DIMENSIONAL COUPLED VIBRATION EQUIVALENT CIRCUIT CONVERTER
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