期刊文献+
共找到3,720篇文章
< 1 2 186 >
每页显示 20 50 100
Simultaneous modulated accelerated radiation therapy for esophageal cancer:A feasibility study 被引量:12
1
作者 Wu-Zhe Zhang Jian-Zhou Chen +6 位作者 De-Rui Li Zhi-Jian Chen Hong Guo Ting-Ting Zhuang Dong-Sheng Li Ming-Zhen Zhou Chuang-Zhen Chen 《World Journal of Gastroenterology》 SCIE CAS 2014年第38期13973-13980,共8页
AIM: To establish the feasibility of simultaneous modulated accelerated radiation therapy (SMART) in esophageal cancer (EC).
关键词 Simultaneous modulated accelerated radiation therapy Three-dimensional conformal radiotherapy Intensity-modulated radiation therapy Esophageal cancer FEASIBILITY
下载PDF
Multi-scale Distribution Pattern of Natural Ramet Population in the Rhizomatous Herb ,Thermopsis lanceolata 被引量:11
2
作者 于飞海 董鸣 《Acta Botanica Sinica》 CSCD 1999年第12期1332-1338,共7页
Thedistributionpatternofnaturalrametpopulationintherhizomatousherb ,Thermopsislanceolata R .Br.,at 5scales (0 .2m ,0 .4m ,0 .6m ,0 .8mand 1.0m)wasinvestigatedusinggridsamplingand spatialauto_correlationanalysis (Mo... Thedistributionpatternofnaturalrametpopulationintherhizomatousherb ,Thermopsislanceolata R .Br.,at 5scales (0 .2m ,0 .4m ,0 .6m ,0 .8mand 1.0m)wasinvestigatedusinggridsamplingand spatialauto_correlationanalysis (Moran’sI)inMaowususandlandofInnerMongoliaofChina .Theresult showedthattherametpopulationhadnon_randomdistributionpatternatfourscales (0 .2m ,0 .4m ,0 .6m and 1.0m) .Themostfrequentlyobservedpatternwascontagiousatthescaleof 0 .2m .Thegenethadsym podialgrowthandnearlyphalanxarchitecture .Thebranchingangleoftherhizomeswasfrom 10°to 30° .The densityoftherametpopulationwasfrom 35to 131ramets·m- 2 .Themeanheightoframetswasbetween 11.0 cmand 2 5.9cm .Thebiomassoftherametpopulationwas 2 6 3.6 3g·m- 2 and 30 6 .19g·m- 2 inthetwo plots,respectively .33.71%and 4 4 .97%ofthebiomassallocationtorhizomeswereobservedandthe biomassallocationtorootswas 2 9.91%and 2 9.95%andthattoleaveswas 2 5.12 %and 36 .35%inthetwo plots ,respectively .Theratioofroottoshootwas 0 .4 4inbothplotswhiletheratioofbelow_toabove_ground biomasswas 2 .12and 3.59,respectively . 展开更多
关键词 Clonalplant Clonalarchitecture Multi_scalepattern Spatialauto_correlationanalysis ther mopsislanceolata
下载PDF
Hybrid vs sequential therapy for eradication of Helicobacter pylori in Taiwan: a prospective randomized trial 被引量:3
3
作者 Kuan-Yang Chen Tsung-Jung Lin +3 位作者 Chin-Lin Lin Hsi-Chang Lee Chung-Kwe Wang Deng-Chyang Wu 《World Journal of Gastroenterology》 SCIE CAS 2015年第36期10435-10442,共8页
AIM: To evaluate the efficacy of sequential vs hybrid therapy in patients with Helicobacter pylori(H. pylori) infection.METHODS: From March 2013 to May 2014,one hundred and seventy-five H. pylori infected patients who... AIM: To evaluate the efficacy of sequential vs hybrid therapy in patients with Helicobacter pylori(H. pylori) infection.METHODS: From March 2013 to May 2014,one hundred and seventy-five H. pylori infected patients who had not been treated for H. pylori before wererandomized to receive either sequential therapy(rabeprazole 20 mg and amoxicillin 1 g twice daily for 5 d,followed by rabeprazole 20 mg,clarithromycin 500 mg and metronidazole 500 mg twice daily for 5 d) or hybrid therapy(rabeprazole 20 mg and amoxicillin 1 g for 7 d,followed by rabeprazole 20 mg,amoxicillin 1 g,clarithromycin 500 mg and metronidazole 500 mg twice daily for 7 d). H. pylori status was confirmed by positive results of both rapid urease test and histology examination or a positive result of culture. Eradication efficacy was assessed by follow-up endoscopy with rapid urease test and histological examination 8 wk after the end of anti-H. pylori therapy,or 13C-urea breath test at least 4 wk after completion of treatment. The primary outcome was H. pylori eradication by intension-to-treat(ITT) and per-protocol(PP) analyses.RESULTS: One hundred and sixty-seven patients(83 patients in the sequential group and 84 patients in the hybrid group) completed the study. The compliance rates were 97.6% and 97.7% for the two groups,respectively. The eradication rate was 78.2% for the sequential group and 92% for the hybrid group by ITT analysis(P = 0.01). The eradication rate was 81.9% for the sequential group and 96.4% for the hybrid group by PP analysis(P = 0.01). Univariate analysis for the clinical and bacterial factors did not identify any risk factors associated with treatment failure. Severe adverse events were observed in 2.3% of patients in the sequential group and 2.4% of those in the hybrid group.CONCLUSION: Due to a grade A(> 95%) success rate for H. pylori eradication by PP analysis,similar compliance and adverse events,hybrid therapy seems to be an appropriate eradication regimen in Taiwan. 展开更多
关键词 HELICOBACTER PYLORI SEQUENTIAL therAPY HYBRID ther
下载PDF
CXC chemokines and chemokine receptors in gastric cancer: From basic findings towards therapeutic targeting 被引量:25
4
作者 Hyo Jin Lee Ik-Chan Song +2 位作者 Hwan-Jung Yun Deog-Yeon Jo Samyong Kim 《World Journal of Gastroenterology》 SCIE CAS 2014年第7期1681-1693,共13页
Gastric cancer is the fourth most common cancer,and the second-highest cause of cancer-related deaths worldwide.Despite extensive research to identify novel diagnostic and therapeutic agents,patients with advanced gas... Gastric cancer is the fourth most common cancer,and the second-highest cause of cancer-related deaths worldwide.Despite extensive research to identify novel diagnostic and therapeutic agents,patients with advanced gastric cancer suffer from a poor quality of life and poor prognosis,and treatment is dependent mainly on conventional cytotoxic chemotherapy.To improve the quality of life and survival of gastric cancer patients,a better understanding of the underlying molecular pathologies,and their application towards the development of novel targeted therapies,is urgently needed.Chemokines are a group of small proteins associated with cytoskeletal rearrangements,the directional migration of several cell types during development and physiology,and the host immune response via interactions with G-protein coupled receptors.There is also growing evidence to suggest that chemokines not only play a role in the immune system,but are also involved in the development and progression of tumors.In gastric cancer,CXC chemokines and chemokine receptors regulate the trafficking of cells in and out of the tumor microenvironment.CXC chemokines and their receptors can also directly influence tumorigenesis by modulating tumor transformation,survival,growth,invasion and metastasis,as well as indirectly by regulating angiogenesis,and tumor-leukocyte interactions.In this review,we will focus on the roles of CXC chemokines and their receptors in the development,progression,and metastasis of gastric tumors,and discuss their therapeutic potential for gastric cancer. 展开更多
关键词 CHEMOKINE Chemokine receptor Gastric neoplasm therapeutic target
下载PDF
Effects of oral tacrolimus as a rapid induction therapy in ulcerative colitis 被引量:3
5
作者 Ken Kawakami Takuya Inoue +12 位作者 Mitsuyuki Murano Ken Narabayashi Sadaharu Nouda Kumi Ishida Yosuke Abe Koji Nogami Nobuyuki Hida Hirokazu Yamagami Kenji Watanabe Eiji Umegaki Shiro Nakamura Tetsuo Arakawa Kazuhide Higuchi 《World Journal of Gastroenterology》 SCIE CAS 2015年第6期1880-1886,共7页
AIM:To determine the efficacy and safety of rapid induction therapy with oral tacrolimus without a meal in steroid-refractory ulcerative colitis(UC)patients.METHODS:This was a prospective,multicenter,observational stu... AIM:To determine the efficacy and safety of rapid induction therapy with oral tacrolimus without a meal in steroid-refractory ulcerative colitis(UC)patients.METHODS:This was a prospective,multicenter,observational study.Between May 2010 and August 2012,49 steroid-refractory UC patients(55 flare-ups)were consecutively enrolled.All patients were treated with oral tacrolimus without a meal at an initial dose of 0.1mg/kg per day.The dose was adjusted to maintain trough whole-blood levels of 10-15 ng/m L for the first 2 wk.Induction of remission at 2 and 4 wk after tacrolimus treatment initiation was evaluated using Lichtiger’s clinical activity index(CAI).RESULTS:The mean CAI was 12.6±3.6 at onset.Within the first 7 d,93.5%of patients maintained high trough levels(10-15 ng/m L).The CAI significantly decreased beginning 2 d after treatment initiation.At 2wk,73.1%of patients experienced clinical responses.After tacrolimus initiation,31.4%and 75.6%of patients achieved clinical remission at 2 and 4 wk,respectively.Treatment was well tolerated.CONCLUSION:Rapid induction therapy with oral tacrolimus shortened the time to achievement of appropriate trough levels and demonstrated a high remission rate 28 d after treatment initiation.Rapid induction therapy with oral tacrolimus appears to be a useful therapy for the treatment of refractory UC. 展开更多
关键词 ULCERATIVE COLITIS TACROLIMUS RAPID induction ther
下载PDF
Thermal Fatigue Behaviour of Co-Based Alloy Coating Obtained by Laser Surface Melt-Casting on High Temperature Alloy 被引量:1
6
作者 ZHU Wei-dong LIU Qi-bin 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2000年第1期39-42,共4页
A thermal fatigue behaviour of Co-based alloy coating obtained by laser surface meltcasting on the high temperature alloy GH33 was studied.The results show that after each time of thermal cycling,the final residual st... A thermal fatigue behaviour of Co-based alloy coating obtained by laser surface meltcasting on the high temperature alloy GH33 was studied.The results show that after each time of thermal cycling,the final residual stress was formed in the melt-casting layer which is attributed to the thermal stress and structural stress.Through the first 50 times of thermal cycling,the morphology of coating still inherits the laser casting one,but the dendrites get bigger;After the second 50 times of thermal cycling,corrosion pits emerge from coating,and mostly in the places where coating and substrate meet.The fatigue damage type of coating belongs to stress corrosion. 展开更多
关键词 laser melt-casting Co-based alloy coating ther mal cycling residual stress corrosion pit
下载PDF
SYNTHESIS AND THERMAL STABILITY OF NANOCOMPOSITE nc-TiN/a-TiB_2 THIN FILMS 被引量:1
7
作者 Y.H.Lu Z.F.Zhou +3 位作者 P.Sit Y.G.Shen K.Y.Li H.Chen 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2005年第3期307-312,共6页
Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum ... Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum annealed at 400, 600, 80 0 and 1000℃ for 1h, respectively. Effects of B content on microstructure, mecha nical behaviors and thermal microstructure stability have been investigated by X -ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nanoindentation measurements. The results indicated that B addition greatly affected both microstructure and mechanical behavior of nc-Ti N/a-TiB2 thin films. With increasing B content the grain size decreased. A maxim um hardness value of about 33GPa was obtained at B content of about 19at.%. The improved mechanical properties of nc-TiN/a-TiB2 films with the addition of B int o TiN were attributed to their densified microstructure with development of fine grain size. Only addition of sufficient B could restrain grain growth during an nealing. High B content resulted in high microstructure stability. The crystalli zation of amorphous matrix occurred at about 800℃, forming TiB or TiB2 crystall ite, depending on B content. Before that no change in bonding configuration was found. 展开更多
关键词 annealing boron reactive unbalanced dc magnetron sputtering ther mal stability nc-TiN/a-TiB2 thin film
下载PDF
THERMAL DECOMPOSITION BEHAVIOR OF AMMONIUM THIO TUNGSTATE in H_2 被引量:1
8
作者 P. F. Xing , L. F. Ma , K. Quan and Y. C. Zhai School of Materials and Metallurgy , Northeastern University , Shenyang 110006 , China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1999年第5期1171-1174,共4页
The ther m al deco m position mechanism of a m m oniu m thiotungstate of the size of 63 ~75 μmin H2 has been investigated by D T A and X R D methods . The ther m al deco m position activationenergies and the ord... The ther m al deco m position mechanism of a m m oniu m thiotungstate of the size of 63 ~75 μmin H2 has been investigated by D T A and X R D methods . The ther m al deco m position activationenergies and the orders of a m m oniu m thiotu ngstate were calculated by means of Kissinger , Freem an Carroll and Coast Redfern m ethods . It w as also obtained that therm al deco m posi tion is cond ucted according to four reaction equations :( N H4) 2 W S4· H2 O(s) ( N H4) 2 W S4(s) + H2 O(g) W S2(s) + 2 N H3(g) + H2(g) + 2 S(s) + H2 O(g) W S2(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) W S2(s) + W(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) . 展开更多
关键词 a m moniu m thiotungstate ther m al deco m position W S2 H2
下载PDF
Frequency and prognostic role of mucosal healing in patients with Crohn's disease and ulcerative colitis after one-year of biological therapy 被引量:2
9
作者 Klaudia Farkas Péter László Lakatos +8 位作者 Mónika Szcs va Pallagi-Kunstár Anita Bálint Ferenc Nagy Zoltán Szepes Noémi Vass Lajos S Kiss Tibor Wittmann Tamás Molnár 《World Journal of Gastroenterology》 SCIE CAS 2014年第11期2995-3001,共7页
AIM: To assess the endoscopic activity before and after a one-year period of biological therapy and to evaluate the frequency of relapses and need for retreatment after stopping the biologicals in patients with Crohn&... AIM: To assess the endoscopic activity before and after a one-year period of biological therapy and to evaluate the frequency of relapses and need for retreatment after stopping the biologicals in patients with Crohn&#x02019;s disease (CD) and ulcerative colitis (UC). 展开更多
关键词 Crohn’ s disease Ulcerative colitis Biological therapy Endoscopy Mucosal healing
下载PDF
Nanoscale mass sensing based on vibration of single-layered graphene sheet in thermal environments 被引量:2
10
作者 S.Ahmad Fazelzadeh Esmaeal Ghavanloo 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第1期84-91,共8页
Based on vibration analysis, single-layered graphene sheet (SLGS) with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysuppo... Based on vibration analysis, single-layered graphene sheet (SLGS) with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysupported configuration. Based on the nonlocal plate the- ory which incorporates size effects into the classical theory, closed-form expressions lot the frequencies and relative fre- quency shills of SLGS-based mass sensor are derived using the Galerkin method. The suggested model is justified by a good agreement between the results given by the present model and available data in literature. The effects of tem- perature difference, nonlocal parameter, the location of the nanoparticle and the number of nanoparticles on the relative frequency shift of the mass sensor are also elucidated. The obtained results show that the sensitivity of the SLGS- based mass sensor increases with increasing temperature difference. 展开更多
关键词 Vibration - Single-layered graphene sheet. ther- mal environment - Nonlocal elasticity theory Relative frequency shift
下载PDF
On stability of elastic domain during isothermal solid-solid phase transformationin a tube configuration 被引量:1
11
作者 Liang Dong Qing-Ping Sun 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第3期683-694,共12页
Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation (during loading) and vanishing (in unloading) of a high strain (martensite) domain. The two events... Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation (during loading) and vanishing (in unloading) of a high strain (martensite) domain. The two events are accompanied by a rapid stress drop/rise due to the formation/vanishing of do- main fronts. From a thermodynamic point of view, both are instability phenomena that occur once the system reaches its critical state. This paper investigates the stability of a shrink- ing cylindrical domain in a tube configuration during unload- ing. The energetics and thermodynamic driving force of the cylindrical domain are quantified by using an elastic inclu- sion model. It is demonstrated that the two domain fronts ex- hibit strong interaction when they come close to each other, which brings a peak in the total energy and a sign change in the thermodynamic driving force. It is proved that such domain front interaction plays an important role in control- ling the stability of the domain and in the occurrence of stress jumps during domain vanishing. It is also shown that the pro- cess is governed by two nondimensional length scales (the normalized tube length and normalized wall-thickness) and that the length scale dependence of the critical domain length and stress jump for the domain vanishing can be quantified by the elastic inclusion model. 展开更多
关键词 Cylindrical elastic domain Stability of domain Domain front Critical domain length Stress jump ~ ther-modynamic driving force
下载PDF
Three-Dimensional Thermo-Elastic-Plastic Finite Element Method Modeling for Predicting Weld-Induced Residual Stresses and Distortions in Steel Stiffened-Plate Structures 被引量:1
12
作者 Myung Su Yi Chung Min Hyun Jeom Kee Paik 《World Journal of Engineering and Technology》 2018年第1期176-200,共25页
The objective of the present paper is to develop nonlinear finite element method models for predicting the weld-induced initial deflection and residual stress of plating in steel stiffened-plate structures. For this p... The objective of the present paper is to develop nonlinear finite element method models for predicting the weld-induced initial deflection and residual stress of plating in steel stiffened-plate structures. For this purpose, three-dimensional thermo-elastic-plastic finite element method computations are performed with varying plate thickness and weld bead length (leg length) in welded plate panels, the latter being associated with weld heat input. The finite element models are verified by a comparison with experimental database which was obtained by the authors in separate studies with full scale measurements. It is concluded that the nonlinear finite element method models developed in the present paper are very accurate in terms of predicting the weld-induced initial imperfections of steel stiffened plate structures. Details of the numerical computations together with test database are documented. 展开更多
关键词 STEEL Stiffened-Plate Structures Weld-Induced Initial Distortion Weld-Induced Residual Stress Nonlinear FINITE ELEMENT Method THREE-DIMENSIONAL ther-mo-Elastic-Plastic FINITE ELEMENT Analysis Full Scale Measurements
下载PDF
Thermo-mechanical Properties of In-situ Formed Al_2O_3-SiC-SiAION Composites
13
作者 HUANG Yalei GU Qiang +2 位作者 WEN Yubin LIU Zhifang LIU Xinhong 《China's Refractories》 CAS 2016年第2期48-52,共5页
Al2 O3 - SiC - SiAION composite specimens have been prepared using fused alumina, ultra fine α-Al2O3, Si and Al powders as starting materials and liquid phenol formaldehyde resin as binder and firing at 1 500 ℃ for ... Al2 O3 - SiC - SiAION composite specimens have been prepared using fused alumina, ultra fine α-Al2O3, Si and Al powders as starting materials and liquid phenol formaldehyde resin as binder and firing at 1 500 ℃ for 3 h in carbon embedded condition. Thermo-mechanical properties of Al2 O3 - SiC - SiAlON composites have been studied. The results show : ( 1 ) Al2 O3 - SiC - SiAION composites can be prepared and sintered at 1 500 ℃ under carbon embedded condition. When Si/Al ratio is 8/0 and 7/1, the prepared composite is Al2O3 - SiC - O' -SiAlON; when Si/Al ratio is 5/3 and 3/5, the pre- pared composite is Al2 O3 - SiC - β-SiAION. ( 2 ) The composites possess high temperature strength properties. Hot modulus of rupture at 1 400 ℃ is 10 - 30 MPa. They are in elastic range up to 1 000 ℃, after which plastic deformation is observed; even at 1 400 ℃, amount of deformation is relatively low. (3) The com- posites possess good thermal shock resistance, their resid- ual strength ratio (AT = 1 100 ℃ ) is 65% - 80%. (4) The marked improvement in thermo-mechanical properties of Al2O3 - SiC - SiAlON composites may be at- tributed to the in-situ formation of SiC, SiAlON and AIN, the fibrous SiC, columnar SiAlON and tabular-like AlN fill in the corundum skeleton structure creating strengthening and toughening effects. 展开更多
关键词 alumina - silicon carbide - SiAlON ther-mo-mechanical properties IN-SITU slide plate
下载PDF
Theoretical Analysis of Simulating the Locked-In Stress in Rock Pore by Thermal Expansion of Hard Rubber
14
作者 Lu Dong Hansheng Geng +1 位作者 Hongfa Xu Yinhao Yang 《Open Journal of Civil Engineering》 2020年第2期83-92,共10页
Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician... Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician Chen Zongji, the locked-in stress problem in underground rock is simulated by the thermal expansion of hard rubber particles. The pore inclusion in rock is assumed to be uniformly distributed spherical cavities. Using the thermal stress theory, the stress of rock with a spherical pore inclusion is equivalent to the thermal stress generated by the spherical hard rubber inclusion. The elastic theory formula of the temperature increment and the equivalent pore pressure of the spherical hard rubber inclusion is derived. The numerical simulation of the rock mass model with a spherical hard rubber inclusion is carried out and compared to the theoretical calculation results<span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> the results show that they are consistent. The method proposed by this paper for simulating stress distribution in rock by thermal stress is reasonable and feasible</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> it has a positive meaning for further study of mechanic phenomenon of rock with micropore inclusion.</span> 展开更多
关键词 Rock Pore Locked-In Stress Similar Simulation Rubber Particles ther-mal Expansion
下载PDF
Complex nature of inheritance of ther mosensitive genic male sterility(TG MS)in rice
15
《Chinese Rice Research Newsletter》 2001年第3期6-7,共2页
关键词 TG MS)in rice Complex nature of inheritance of ther mosensitive genic male sterility MS
下载PDF
基于变量敏感度筛选的回归型支持向量机的数控机床热误差预测
16
作者 李铁军 崔尚仪 张义民 《机械设计与制造》 北大核心 2024年第9期41-43,50,共4页
随着机械制造行业的迅猛发展,对于数控机床的定位精度要求越来越高。为了提高机床定位精度,建立了基于变量敏感度筛选与回归型支持向量机(SVR)混合模型,并将其用于数控机床热误差预测方法。该方法基于对变量敏感度分析,筛选掉敏感度低... 随着机械制造行业的迅猛发展,对于数控机床的定位精度要求越来越高。为了提高机床定位精度,建立了基于变量敏感度筛选与回归型支持向量机(SVR)混合模型,并将其用于数控机床热误差预测方法。该方法基于对变量敏感度分析,筛选掉敏感度低的干扰自变量。本方法与基本SVR模型对数控机床热误差预测值进行对比,结果表明基本SVR受到敏感度低的干扰自变量影响,预测结果与实测热误差结果偏差较大;经过变量敏感度筛选之后的SVR混合模型预测值具有更高的准确度,验证了此模型的可行性。 展开更多
关键词 数控机床 回归型支持向量机 变量敏感度筛选 热误差
下载PDF
Near-field radiative thermoelectric energy converters: a review 被引量:4
17
作者 Eric TERVO Elham BAGHERISERESHKI Zhuomin ZHANG 《Frontiers in Energy》 SCIE CSCD 2018年第1期5-21,共17页
Radiative thermoelectric energy converters, which include thermophotovoltaic cells, thermoradiative cells, electroluminescent refrigerators, and negative elec- troluminescent refrigerators, are semiconductor p-n devic... Radiative thermoelectric energy converters, which include thermophotovoltaic cells, thermoradiative cells, electroluminescent refrigerators, and negative elec- troluminescent refrigerators, are semiconductor p-n devices that either generate electricity or extract heat from a cold body while exchanging thermal radiation with their surroundings. If this exchange occurs at micro or nanoscale distances, power densities can be greatly enhanced and near-field radiation effects may improve performance. This review covers the fundamentals of near-field thermal radiation, photon entropy, and none- quilibrium effects in semiconductor diodes that underpin device operation. The development and state of the art of these near-field converters are discussed in detail, and remaining challenges and opportunities for progress are identified. 展开更多
关键词 energy conversion systems luminescentrefrigeration near-field radiation therMOPHOTOVOLTAIC ther-moradiative cell
原文传递
BMS电路板多模块协同热-力耦合建模及仿真分析
18
作者 何莉萍 原江鑫 李耀东 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第8期135-144,共10页
针对现有电动汽车电池管理系统(BMS)电路板研究仅仅考虑单一功能模块的温度场及其散热效果,缺乏考虑BMS多个功能模块在温度场和力场下的相互影响及协同效应的研究的情况,以某商用BMS电路板为研究对象,采用ANSYS构建了表征BMS多模块协同... 针对现有电动汽车电池管理系统(BMS)电路板研究仅仅考虑单一功能模块的温度场及其散热效果,缺乏考虑BMS多个功能模块在温度场和力场下的相互影响及协同效应的研究的情况,以某商用BMS电路板为研究对象,采用ANSYS构建了表征BMS多模块协同作用下的热-力耦合数值仿真分析模型并验证了其有效性.在此基础上,针对BMS电路板各功能模块温度场及热变形行为开展了数值仿真研究.结果表明:BMS电路板温度分布不均,最大温差达20.5℃.均衡模块存在积热,温度高达54.4℃.高温导致电路板组件发生热膨胀变形,同时电路板约束诱发均衡模块及供电模块边缘的贴片电阻出现热应力集中,两者共同作用致使BMS均衡模块、供电模块产生凸起翘曲变形,且Z轴热变形量随着温度升高而增大,最大变形量达9.5μm,应针对BMS电路板上积热模块开展散热优化设计. 展开更多
关键词 电动汽车 BMS 多模块 温度场 热变形 热-力耦合 仿真分析
下载PDF
Thermal Behaviors of 2-(Dinitromethylene)-1,3- diazacycloheptane (DNDH) 被引量:1
19
作者 吕磊 徐抗震 +4 位作者 王刚 罗金安 宋纪蓉 王伯周 赵凤起 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2011年第8期1576-1582,共7页
2-(Dinitromethylene)-1,3-diazacycloheptane (DNDH) was prepared by the reaction of 1,1-diamino-2,2-dinitro- ethylene (FOX-7) with 1,4-diaminoethane in NMP. Thermal decomposition behavior of DNDH was studied under... 2-(Dinitromethylene)-1,3-diazacycloheptane (DNDH) was prepared by the reaction of 1,1-diamino-2,2-dinitro- ethylene (FOX-7) with 1,4-diaminoethane in NMP. Thermal decomposition behavior of DNDH was studied under the non-isothermal conditions with DSC method, and presents only one intensely exothermic decomposition process The kinetic equation of the decomposition reaction is da/dT= 103388× 3a2/3exp(--3.353 ×10^5/RT)/fl. The critical temperature of thermal explosion is 215.97℃. Specific heat capacity of DNDH was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is 215.40 Jomol-1,K-1 at 298.15 K. Adiabatic time-to-explosion was calculated to be 92.07 s. DNDH has same thermal stability to FOX-7. 展开更多
关键词 2-(dinitromethylene)-l 3-diazacycloheptane (DNDH) l l-diamino-2 2-dinitroethylene (FOX-7) ther-mal behavior nitrogen heterocycles therMOCHEMISTRY
原文传递
基于共轭梯度法的晶闸管电热耦合模型快速求解方法研究 被引量:1
20
作者 刘隆晨 李龙蛟 +3 位作者 彭东 禹佳 杨玥坪 喻悦箫 《电源学报》 CSCD 北大核心 2024年第3期54-61,共8页
为解决传统求解技术在处理效率和计算成本上的局限问题,针对晶闸管电热应力耦合交互模型,提出一种基于共轭梯度法的高效解析方法。通过优化迭代过程和收敛条件来显著提升求解效率和精度。新的参数选择策略被引入以自动调整算法迭代步长... 为解决传统求解技术在处理效率和计算成本上的局限问题,针对晶闸管电热应力耦合交互模型,提出一种基于共轭梯度法的高效解析方法。通过优化迭代过程和收敛条件来显著提升求解效率和精度。新的参数选择策略被引入以自动调整算法迭代步长,加快收敛速度,减少计算资源消耗。相比传统求解方法,所提优化方法在求解时间上平均减少10%,求解精度提高8%。这一进展证明自适应共轭梯度法在电热应力耦合模型快速求解中的有效性,可为电力电子设备热管理提供高效、可靠的计算工具。所提方法在多种测试条件下均表现出显著的提升效率和良好的精确度,为晶闸管电热耦合模型的高效求解提供了创新方案,同时对电力电子领域的相关研究具有重要的实践意义。 展开更多
关键词 直流输电系统 晶闸管 电热耦合 共轭梯度法 优化求解
下载PDF
上一页 1 2 186 下一页 到第
使用帮助 返回顶部