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Fast UAV path planning in urban environments based on three-step experience buffer sampling DDPG
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作者 Shasha Tian Yuanxiang Li +4 位作者 Xiao Zhang Lu Zheng Linhui Cheng Wei She Wei Xie 《Digital Communications and Networks》 SCIE CSCD 2024年第4期813-826,共14页
The path planning of Unmanned Aerial Vehicle(UAV)is a critical issue in emergency communication and rescue operations,especially in adversarial urban environments.Due to the continuity of the flying space,complex buil... The path planning of Unmanned Aerial Vehicle(UAV)is a critical issue in emergency communication and rescue operations,especially in adversarial urban environments.Due to the continuity of the flying space,complex building obstacles,and the aircraft's high dynamics,traditional algorithms cannot find the optimal collision-free flying path between the UAV station and the destination.Accordingly,in this paper,we study the fast UAV path planning problem in a 3D urban environment from a source point to a target point and propose a Three-Step Experience Buffer Deep Deterministic Policy Gradient(TSEB-DDPG)algorithm.We first build the 3D model of a complex urban environment with buildings and project the 3D building surface into many 2D geometric shapes.After transformation,we propose the Hierarchical Learning Particle Swarm Optimization(HL-PSO)to obtain the empirical path.Then,to ensure the accuracy of the obtained paths,the empirical path,the collision information and fast transition information are stored in the three experience buffers of the TSEB-DDPG algorithm as dynamic guidance information.The sampling ratio of each buffer is dynamically adapted to the training stages.Moreover,we designed a reward mechanism to improve the convergence speed of the DDPG algorithm for UAV path planning.The proposed TSEB-DDPG algorithm has also been compared to three widely used competitors experimentally,and the results show that the TSEB-DDPG algorithm can archive the fastest convergence speed and the highest accuracy.We also conduct experiments in real scenarios and compare the real path planning obtained by the HL-PSO algorithm,DDPG algorithm,and TSEB-DDPG algorithm.The results show that the TSEBDDPG algorithm can archive almost the best in terms of accuracy,the average time of actual path planning,and the success rate. 展开更多
关键词 Unmanned aerial vehicle Path planning Deep deterministic policy gradient three-step experience buffer Particle swarm optimization
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Enhancing corrosion resistance of 7150 Al alloy using novel three-step aging process 被引量:1
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作者 孙睿吉 孙擎擎 +3 位作者 谢跃煌 董朋轩 陈启元 陈康华 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第5期1201-1210,共10页
The effects of a novel three-step aging process (T76+T6) on the electrochemical corrosion behavior of 7150 extruded aluminum alloy were evaluated and compared with those of the conventional retrogression and re-agi... The effects of a novel three-step aging process (T76+T6) on the electrochemical corrosion behavior of 7150 extruded aluminum alloy were evaluated and compared with those of the conventional retrogression and re-aging process (T77). The open circuit potential (OCP), cyclic polarization and electrochemical impedance spectra (EIS) of the A1 alloys were measured after treatment in three solutions (3.5% NaCl (mass fraction); 10 mmol/L NaCl + 0.1 mol/L Na2SO4; 4 mol/L NaCl + 0.5 mol/L KNO3 + 0.1 mol/L HNO3). The parameters including the corrosion potential, pitting potential, pit transition potential and steepness, and potential differences were extensively discussed to evaluate the corrosion behavior of the Al alloys. The electrochemical and scanning electron microscopy (SEM) data show that compared with the 7150-T77 Al alloy, the T76 + T6 aged 7150 A1 alloy exhibits better resistance to pitting corrosion, inter-granular corrosion (IGC) and exfoliation corrosion, which is attributed to further coarsening and inter-spacing of the grain boundary particles (GBPs) as revealed by transmission electron microscopy. Furthermore, the hardness tests indicate that an attractive combination of strength and corrosion resistance was obtained for the 7150 Al alloy with T76 + T6 treatment. 展开更多
关键词 7150 aluminum alloy novel three-step aging cyclic polarization electrochemical impedance spectroscopy
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Effect of three-step homogenization on microstructure and properties of 7N01 aluminum alloys 被引量:8
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作者 Hua-qiang LIN Ling-ying YE +4 位作者 Lin SUN Tao XIAO Sheng-dan LIU Yun-lai DENG Xin-ming ZHANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第5期829-838,共10页
The effect of different homogenization treatments on the microstructure and properties of the 7N01 aluminum alloy was investigated using hardness measurements, electrical conductivity measurements, tensile and slow st... The effect of different homogenization treatments on the microstructure and properties of the 7N01 aluminum alloy was investigated using hardness measurements, electrical conductivity measurements, tensile and slow strain rate tests, electron probe microanalysis, optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results revealed that three-step homogenization improved the uniformity of Zr distribution by eliminating segregation of the main alloying elements. During the second homogenization step at 350 °C for 10 h, coarse and strip-like equilibrium η phases formed which assisted the nucleation of Al3Zr dispersoids and reduced the width of the precipitate-free zone of A13Zr dispersoids. As a result, coarse recrystallization was greatly reduced after homogenization at 200 °C, 2 h + 350 °C, 10 h + 470 °C, 12 h, which contributed to improving the overall properties of the 7N01 aluminum alloys. 展开更多
关键词 7N01 aluminum alloy three-step homogenization microstzucture mechanical properties stress corrosion cracking
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Effect of a novel three-step aging on strength, stress corrosion cracking and microstructure of AA7085 被引量:4
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作者 陈送义 陈康华 +3 位作者 董朋轩 叶升平 黄兰萍 阳代军 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第8期1858-1862,共5页
The influence of a novel three-step aging on strength, stress corrosion cracking(SCC) and microstructure of AA7085 was investigated by tensile testing and slow strain rate testing combined with transmission electron m... The influence of a novel three-step aging on strength, stress corrosion cracking(SCC) and microstructure of AA7085 was investigated by tensile testing and slow strain rate testing combined with transmission electron microscopy(TEM). The results indicate that with the increase of second-step aging time of two-step aging, the mechanical properties increase first and then decrease, while the SCC resistance increases. Compared with two-step aging, three-step aging treatment improves SCC resistance and the strength increases by about 5%. The effects of novel three-step aging on strength and SCC resistance are explained by the role of matrix precipitates and grain boundary precipitates, respectively. 展开更多
关键词 7085 aluminum alloy three-step aging STRENGTH stress corrosion cracking MICROSTRUCTURE
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Short-term efficacy of robotic and laparoscopic spleen-preserving splenic hilar lymphadenectomy via Huang’s three-step maneuver for advanced upper gastric cancer: Results from a propensity scorematched study 被引量:2
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作者 Jia-Bin Wang Zhi-Yu Liu +14 位作者 Qi-Yue Chen Qing Zhong Jian-Wei Xie Jian-Xian Lin Jun Lu Long-Long Cao Mi Lin Ru-Hong Tu Ze-Ning Huang Ju-Li Lin Hua-Long Zheng Si-Jin Que Chao-Hui Zheng Chang-Ming Huang Ping Li 《World Journal of Gastroenterology》 SCIE CAS 2019年第37期5641-5654,共14页
BACKGROUND Robotic surgery has been considered to be significantly better than laparoscopic surgery for complicated procedures.AIM To explore the short-term effect of robotic and laparoscopic spleen-preserving splenic... BACKGROUND Robotic surgery has been considered to be significantly better than laparoscopic surgery for complicated procedures.AIM To explore the short-term effect of robotic and laparoscopic spleen-preserving splenic hilar lymphadenectomy(SPSHL)for advanced gastric cancer(GC)by Huang’s three-step maneuver.METHODS A total of 643 patients who underwent SPSHL were recruited from April 2012 to July 2017,including 35 patients who underwent robotic SPSHL(RSPSHL)and 608 who underwent laparoscopic SPSHL(LSPSHL).One-to-four propensity score matching was used to analyze the differences in clinical data between patients who underwent robotic SPSHL and those who underwent laparoscopic SPSHL.RESULTS In all,175 patients were matched,including 35 patients who underwent RSPSHL and 140 who underwent LSPSHL.After matching,there were no significant differences detected in the baseline characteristics between the two groups.Significant differences in total operative time,estimated blood loss(EBL),splenic hilar blood loss(SHBL),splenic hilar dissection time(SHDT),and splenic trunk dissection time were evident between these groups(P<0.05).Furthermore,no significant differences were observed between the two groups in the overall noncompliance rate of lymph node(LN)dissection(62.9%vs 60%,P=0.757),number of retrieved No.10 LNs(3.1±1.4 vs 3.3±2.5,P=0.650),total number of examined LNs(37.8±13.1 vs 40.6±13.6,P=0.274),and postoperative complications(14.3%vs 17.9%,P=0.616).A stratified analysis that divided the patients receiving RSPSHL into an early group(EG)and a late group(LG)revealed that the LG experienced obvious improvements in SHDT and length of stay compared with the EG(P<0.05).Logistic regression showed that robotic surgery was a significantly protective factor against both SHBL and SHDT(P<0.05).CONCLUSION RSPSHL is safe and feasible,especially after overcoming the early learning curve,as this procedure results in a radical curative effect equivalent to that of LSPSHL. 展开更多
关键词 Advanced gastric cancer ROBOTIC surgery LAPAROSCOPIC surgery Dissection of SPLENIC HILAR lymph node Propensity score matching Huang’s three-step MANEUVER
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Auxiliary principle and three-step iterative algorithms for generalized set-valued strongly nonlinear mixed variational-like inequalities 被引量:1
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作者 徐海丽 郭兴明 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第6期721-729,共9页
An auxiliary principle technique to study a class of generalized set-valued strongly nonlinear mixed variational-like inequalities is extended. The existence and uniqueness of the solution of the auxiliary problem for... An auxiliary principle technique to study a class of generalized set-valued strongly nonlinear mixed variational-like inequalities is extended. The existence and uniqueness of the solution of the auxiliary problem for the generalized set-valued strongly nonlinear mixed variational-like inequalities are proved, a novel and innovative three-step iterative algorithm to compute approximate solution is constructed, and the existence of the solution of the generalized set-valued strongly nonlinear mixed variational-like inequality is shown using the auxiliary principle iterative sequences generated by the algorithm technique. The convergence of three-step is also proved. 展开更多
关键词 mixed variational-like inequality three-step iterative algorithm set-valued mapping auxiliary principle technique
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ZnO micro-nano composite hydrophobic film prepared by the three-step method
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作者 马恺 李华 +3 位作者 张晗 许小亮 公茂刚 杨周 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第5期1942-1946,共5页
The hydrophobicity of the lotus leaf is mainly due to its surface micro-nano composite structure. In order to mimic the lotus structure, ZnO micro-nano composite hydrophobic films were prepared via the three-step meth... The hydrophobicity of the lotus leaf is mainly due to its surface micro-nano composite structure. In order to mimic the lotus structure, ZnO micro-nano composite hydrophobic films were prepared via the three-step method. On thin buffer films of SiO2, which were first fabricated on glass substrates by the so,gel dip-coating method, a ZnO seed layer was deposited via RF magnetron sputtering. Then two different ZnO films, micro-nano and micro-only flowerlike structures, were grown by the hydrothermal method. The prepared films have different hydrophobic properties after surface modification. The structures of the obtained ZnO films were characterized using x-ray diffraction and field-emission scanning electron microscopy. A conclusion that a micro-nano composite structure is more beneficial to hydrophobicity than a micro-only structure was obtained through research into the effect of structure on hydrophobic properties. 展开更多
关键词 three-step method ZNO micro-nano structure hydrophobic film
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Three-step acupuncture and cupping therapy:an effective approach to treat cervicogenic headache
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作者 Xiong-Zhi Wu 《Traditional Medicine Research》 2019年第1期3-3,共1页
As early as 1983,Sjaastad proposed the concept of cervicogenic headache(CH)in the World Headache Conference,that is,the pain from upper cervical joints and muscles can be referred to the head.CH is a group of syndrome... As early as 1983,Sjaastad proposed the concept of cervicogenic headache(CH)in the World Headache Conference,that is,the pain from upper cervical joints and muscles can be referred to the head.CH is a group of syndromes mainly caused by dysfunction of the upper cervical spine and its component muscles,ligaments,bony,vertebral arteries and/or soft tissue elements,usually not accompanied by neck pain.Therefore,the treatment strategy of CH focuses on pain relief and repair cervical lesions.Patients with painful disorders of upper cervical zygapophysial joints showed significant headache relief after directly treated at disordered cervical joints[1]. 展开更多
关键词 three-step ACUPUNCTURE and CUPPING therapy TREAT cervicogenic HEADACHE
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Three-Step Difference Scheme for Solving Nonlinear Time-Evolution Partial Differential Equations
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作者 GONG Jing WANG Bin JI Zhong-Zhen 《Atmospheric and Oceanic Science Letters》 CSCD 2013年第6期423-427,共5页
In this paper, a special three-step difference scheme is applied to the solution of nonlinear time-evolution equations, whose coefficients are determined according to accuracy constraints, necessary conditions of squa... In this paper, a special three-step difference scheme is applied to the solution of nonlinear time-evolution equations, whose coefficients are determined according to accuracy constraints, necessary conditions of square conservation, and historical observation information under the linear supposition. As in the linear case, the schemes also have obvious superiority in overall performance in the nonlinear case compared with traditional finite difference schemes, e.g., the leapfrog(LF) scheme and the complete square conservation difference(CSCD) scheme that do not use historical observations in determining their coefficients, and the retrospective time integration(RTI) scheme that does not consider compatibility and square conservation. Ideal numerical experiments using the one-dimensional nonlinear advection equation with an exact solution show that this three-step scheme minimizes its root mean square error(RMSE) during the first 2500 integration steps when no shock waves occur in the exact solution, while the RTI scheme outperforms the LF scheme and CSCD scheme only in the first 1000 steps and then becomes the worst in terms of RMSE up to the 2500th step. It is concluded that reasonable consideration of accuracy, square conservation, and historical observations is also critical for good performance of a finite difference scheme for solving nonlinear equations. 展开更多
关键词 three-step difference scheme NONLINEAR square conservation accuracy historical observations
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JOINT RANDOM OPTIMIZED THREE-STEP SEARCH ALGORITHM BASED-ON GRAY AND CHROMATIC INFORMATION
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作者 Liu Zhixin Liu Tieyan Zhang Xudong(Dept. of Electronic Engineering, Tsinghua University, Beijing 100084) 《Journal of Electronics(China)》 2002年第2期215-217,共3页
In this letter, an improved three-step search algorithm is presented, which uses both gray and chromatic information to boost the performance with random optimization and converge the motion vectors to global optima. ... In this letter, an improved three-step search algorithm is presented, which uses both gray and chromatic information to boost the performance with random optimization and converge the motion vectors to global optima. Experimental results show that this algorithm can efficiently improve the PSNR after motion compensation. 展开更多
关键词 Motion estimation Random optimization three-step search
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General Convergence Analysis for Three-step Projection Methods and Applications to Variational Problems
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作者 L UO Hong-lin L UO Hui-lin 《Chinese Quarterly Journal of Mathematics》 CSCD 2009年第2期239-243,共5页
First a general model for a three-step projection method is introduced, and second it has been applied to the approximation solvability of a system of nonlinear variational inequality problems in a Hilbert space setti... First a general model for a three-step projection method is introduced, and second it has been applied to the approximation solvability of a system of nonlinear variational inequality problems in a Hilbert space setting. Let H be a real Hilbert space and K be a nonempty closed convex subset of H. For arbitrarily chosen initial points x0, y0, z0 ∈ K, compute sequences xn, yn, zn such thatT : K→ H is a nonlinear mapping onto K. At last three-step models are applied to some variational inequality problems. 展开更多
关键词 two-step model general three-step model system of strongly monotonic non-linear variational inequalities projection formulas convergence of three-projection method
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A new three-step procedure for pancreatic head carcinoma with invasion of superior mesenteric artery
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作者 Rui Tang Jia-Hong Dong 《Hepatobiliary & Pancreatic Diseases International》 SCIE CAS CSCD 2018年第4期286-289,共4页
Pancreatic head carcinoma is characterized by high malignancy and a low survival rate and its mortality ranks fourth for malignant tumors with a 5-year survival rate of only 5%[1].Treatment of this cancer relies on su... Pancreatic head carcinoma is characterized by high malignancy and a low survival rate and its mortality ranks fourth for malignant tumors with a 5-year survival rate of only 5%[1].Treatment of this cancer relies on surgical resection.However,the resection rate is only about 20%,because majority of the patients are classified as unresectable when diagnosed due to distant metastasis or 展开更多
关键词 SMA A new three-step procedure for pancreatic head carcinoma with invasion of superior mesenteric artery
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Numerical Simulation of Wave Forces on Seabed Pipelines 被引量:2
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作者 Li, YC Chen, B Lai, GZ 《China Ocean Engineering》 SCIE EI 1998年第2期203-211,共9页
A three-step finite element method (FEM) together with Large Eddy Simulation (LES) is applied to incompressible turbulent flow around seabed pipelines at relatively high Reynolds numbers. Both two dimensional and thre... A three-step finite element method (FEM) together with Large Eddy Simulation (LES) is applied to incompressible turbulent flow around seabed pipelines at relatively high Reynolds numbers. Both two dimensional and three-dimensional numerical simulation is carried out to determine the three-dimensional effect. The results of numerical simulation agree quite well with the wave forces acting on pipeline models measured in physical model test. 展开更多
关键词 three-step finite element method large eddy simulation seabed pipeline wave force
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Different methods of acupuncture for relief of pain due to liver cancer:A network meta-analysis 被引量:1
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作者 Hong-Yuan Mou Jing Chen +1 位作者 Zuo-Yun Chen Hong Du 《World Journal of Meta-Analysis》 2022年第2期52-62,共11页
BACKGROUND Pain in the liver is a common symptom of liver cancer in late stages,and the pain incidence rate exceeds 50%[1].In serious cancer pain,morphine and other major analgesics have been commonly administrated fo... BACKGROUND Pain in the liver is a common symptom of liver cancer in late stages,and the pain incidence rate exceeds 50%[1].In serious cancer pain,morphine and other major analgesics have been commonly administrated for clinical treatments,and their effects are accurate,but with a high incidence of side effects,such as nausea,vomiting,constipation,and other conditions.Acupuncture is a traditional Chinese medicine therapy.There have been many randomized controlled trials addressing the safety and usefulness of different methods of acupuncture in alleviating liver cancer pain.However,which of these methods is the most effective method is still unclear.AIM To compare the effectiveness of different acupuncture methods for alleviating pain due to liver cancer.METHODS Eligible studies were retrieved from eight databases(the Cochrane Library,PubMed,EMBASE,Medline,CNKI,CBM,Chongqing VIP,and Wan Fang Database)up to March 31,2021 and screened based on the established inclusion and exclusion criteria.The quality of the include studies was evaluated.Stata software was applied for statistical analyses.Publication bias of the included studies was also determined.Finally,the network meta-analysis was carried out to evaluate the efficacy of acupuncture methods for relief of pain due to liver cancer.RESULTS A total of eight randomized controlled trials were included in the network metaanalysis.Eight trials(covering 5 treatments and 734 patients)provided data suitable for analysis.Most trials focused on short-term effects and many were classed as being of poor quality with a high risk of bias,commonly associated with lack of blinding(which was sometimes impossible to achieve).End of treatment results showed that four interventions,including wrist-ankle acupuncture,triple puncture and remaining needle acupuncture,Tian Yuan acupuncture,and block acupuncture,produced a statistically significant reduction in pain when compared with the three-step analgesic ladder therapy.The surface under the cumulative ranking sorting results showed that triple puncture and remaining needle acupuncture had a relatively high effective rate.CONCLUSION The network meta-analysis results indicate that the overall effectiveness of triple puncture and remaining needle acupuncture is better than the other therapies. 展开更多
关键词 PAIN Liver cancer ACUPUNCTURE Network meta-analysis EFFECTIVENESS three-step analgesic ladder
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Study on the wind field and pollutant dispersion in street canyons using a stable numerical method
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作者 Dennis Y.C. LEUNG 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2005年第3期488-490,共3页
A stable finite element method for the time dependent Navier-Stokes equations was used for studying the wind flow and pollutant dispersion within street canyons. A three-step fractional method was used to solve the ve... A stable finite element method for the time dependent Navier-Stokes equations was used for studying the wind flow and pollutant dispersion within street canyons. A three-step fractional method was used to solve the velocity field and the pressure field separately from the governing equations. The Streamline Upwind Petrov-Galerkin(SUPG) method was used to get stable numerical results. Numerical oscillation was minimized and satisfactory results can be obtained for flows at high Reynolds numbers. Simulating the flow over a square cylinder within a wide range of Reynolds numbers validates the wind field model. The Strouhal numbers obtained from the numerical simulation had a good agreement with those obtained from experiment. The wind field model developed in the present study is applied to simulate more complex flow phenomena in street canyons with two different building configurations. The results indicated that the flow at rooftop of buildings might not be assumed parallel to the ground as some numerical modelers did. A counter-clockwise rotating vortex may be found in street canyons with an inflow from the left to right. In addition, increasing building height can increase velocity fluctuations in the street canyon under certain circumstances, which facilitate pollutant dispersion. At high Reynolds numbers, the flow regimes in street canyons do not change with inflow velocity. 展开更多
关键词 finite element method Streamline Upwind Petrov-Galerkin method three-step fractional method
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Application of CLEAR-VOF method to wave and flow simulations
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作者 Ying-wei SUN Hai-gui KANG 《Water Science and Engineering》 EI CAS 2012年第1期67-78,共12页
A two-dimensional numerical model based on the Navier-Stokes equations and computational Lagrangian-Eulerian advection remap-volume of fluid (CLEAR-VOF) method was developed to simulate wave and flow problems. The N... A two-dimensional numerical model based on the Navier-Stokes equations and computational Lagrangian-Eulerian advection remap-volume of fluid (CLEAR-VOF) method was developed to simulate wave and flow problems. The Navier-Stokes equations were discretized with a three-step finite element method that has a third-order accuracy. In the CLEAR-VOF method, the VOF function F was calculated in the Lagrangian manner and allowed the complicated free surface to be accurately captured. The propagation of regular waves and solitary waves over a flat bottom, and shoaling and breaking of solitary waves on two different slopes were simulated with this model, and the numerical results agreed with experimental data and theoretical solutions. A benchmark test of dam-collapse flow was also simulated with an unstructured mesh, and the capability of the present model for wave and flow simulations with unstructured meshes, was verified. The results show that the model is effective for numerical simulation of wave and flow problems with both structured and unstructured meshes. 展开更多
关键词 water wave water flow numerical simulation CLEAR-VOF three-step finite element method
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Discussion on the clinical significance of moxibustion in improving cancer pain
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作者 Xian-man Wei Dong-xin Tang +3 位作者 Feng-xi Long Qian Deng Han Shao Zhu Yang 《TMR Theory and Hypothesis》 2019年第3期219-224,共6页
In clinic, most patients with middle-late cancer suffer from cancer pain, which seriously affects the confidence and compliance of treatment. However, the side effects of the three-step analgesic therapy, which is wid... In clinic, most patients with middle-late cancer suffer from cancer pain, which seriously affects the confidence and compliance of treatment. However, the side effects of the three-step analgesic therapy, which is widely used at present, are gradually manifested, aggravating patients' resistance to treatment. The role of Moxibustion in relieving pain has been gradually recognized and used in various professional fields. Because of its advantages of non-toxic side effects, simple operation, economic benefits, pain relief and immunity enhancement, moxibustion has been paid more and more attention. 展开更多
关键词 MOXIBUSTION CANCER PAIN three-step THERAPY
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Implementation of motion estimator algorithm with 1/4 pixel accuracy based on FPGA
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作者 向厚振 王鹏 +1 位作者 姚娟 张志杰 《Journal of Measurement Science and Instrumentation》 CAS 2012年第4期341-344,共4页
After research on the motion estimation algorithm in video coding, a motion estimator algorithm with 1/4 pixel ac- curacy is implemented based on fie/d-programmable gate array (FPGA). The motion estimation algorithm... After research on the motion estimation algorithm in video coding, a motion estimator algorithm with 1/4 pixel ac- curacy is implemented based on fie/d-programmable gate array (FPGA). The motion estimation algorithm module is made up of the 1[4 pixel interpolation module with serial input and parallel output, the three step search module and the block match- ing module, which can use relatively less Wiener filters for interpolation operation. Experiment results show that the hard- ware design has less consumption of the logical resource, higher stability and lower power consumption. 展开更多
关键词 H. 264/AVC 1/4 pixel three-step search motion estimation field-programmable gate array (FPGA)
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Forecasting China's per Capita Carbon Emissions under a New Three-step Economic Development Strategy 被引量:2
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作者 杜强 王宁 车雷 《Journal of Resources and Ecology》 CSCD 2015年第5期318-323,共6页
Under the context of the New Three-step strategy of Chinese economic development, we use the reverse tracing method and petroleum, natural gas and coal as sources of carbon emissions. To eliminate the impact of region... Under the context of the New Three-step strategy of Chinese economic development, we use the reverse tracing method and petroleum, natural gas and coal as sources of carbon emissions. To eliminate the impact of regional and technological levels in the energy conversion process we improved the IPAT model and used it to predict and analyze China’s per capita carbon emissions in three assumed scenarios up to 2050. We found that China’s per capita carbon emissions peak wil occur respectively in 2020 and 2030 in different assumed scenarios; national per capita carbon emissions wil reach 2.0127–2.6791 tons; China’s per capita carbon emissions wil grow continuously at an average rate of 2.25%–3.40% per year before the peak year and then wil decline at a rate of 1.33%–1.78% per year. By the year of 2050, national per capita carbon emissions wil be 1.3147–1.8817 tons. 展开更多
关键词 New three-step strategy IPAT model carbon emissions forecasting
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Strength and fatigue properties of three-step sintered dense nanocrystal hydroxyapatite bioceramics 被引量:4
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作者 Wen-Guang GUO Zhi-Ye QIU +5 位作者 Han CUI Chang-Ming WANG Xiao-Jun ZHANG In-Seop LEE Yu-Qi DONG Fu-Zhai CUI 《Frontiers of Materials Science》 SCIE CSCD 2013年第2期190-195,共6页
Dense hydroxyapatite (HA) ceramic is a promising material for hard tissue repair due to its unique physical properties and biologic properties. However, the brittleness and low compressive strength of traditional HA... Dense hydroxyapatite (HA) ceramic is a promising material for hard tissue repair due to its unique physical properties and biologic properties. However, the brittleness and low compressive strength of traditional HA ceramics limited their applications, because previous sintering methods produced HA ceramics with crystal sizes greater than nanometer range. In this study, nano-sized HA powder was employed to fabricate dense nanocrystal HA ceramic by high pressure molding, and followed by a three-step sintering process. The phase composition, microstructure, crystal dimension and crystal shape of the sintered ceramic were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties of the HA ceramic were tested, and cytocompatibility was evaluated. The phase of the sintered ceramic was pure HA, and the crystal size was about 200 nm. The compressive strength and elastic modulus of the HA ceramic were comparable to human cortical bone, especially the good fatigue strength overcame brittleness of traditional sintered HA ceramics. Cell attachment experiment also demonstrated that the ceramics had a good cytocompatibility. 展开更多
关键词 nanocrystal hydroxyapatite ceramic three-step sintering MECHANICALPROPERTY fatigue strength cytocom patibility
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