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Localized wave solutions and interactions of the (2+1)-dimensional Hirota-Satsuma-Ito equation
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作者 巩乾坤 王惠 王云虎 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期409-416,共8页
This paper studies the(2+1)-dimensional Hirota-Satsuma-Ito equation.Based on an associated Hirota bilinear form,lump-type solution,two types of interaction solutions,and breather wave solution of the(2+1)-dimensional ... This paper studies the(2+1)-dimensional Hirota-Satsuma-Ito equation.Based on an associated Hirota bilinear form,lump-type solution,two types of interaction solutions,and breather wave solution of the(2+1)-dimensional Hirota-Satsuma-Ito equation are obtained,which are all related to the seed solution of the equation.It is interesting that the rogue wave is aroused by the interaction between one-lump soliton and a pair of resonance stripe solitons,and the fusion and fission phenomena are also found in the interaction between lump solitons and one-stripe soliton.Furthermore,the breather wave solution is also obtained by reducing the two-soliton solutions.The trajectory and period of the one-order breather wave are analyzed.The corresponding dynamical characteristics are demonstrated by the graphs. 展开更多
关键词 lump solution rogue wave solution breather wave solution (2+1)-dimensional Hirota-Satsuma-Ito equation
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Abundant invariant solutions of extended(3+1)-dimensional KP-Boussinesq equation
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作者 Hengchun Hu Jiali Kang 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第11期167-174,共8页
Lie group analysis method is applied to the extended(3+1)-dimensional Kadomtsev–Petviashvili–Boussinesq equation and the corresponding similarity reduction equations are obtained with various infinitesimal generator... Lie group analysis method is applied to the extended(3+1)-dimensional Kadomtsev–Petviashvili–Boussinesq equation and the corresponding similarity reduction equations are obtained with various infinitesimal generators.By selecting suitable arbitrary functions in the similarity reduction solutions,we obtain abundant invariant solutions,including the trigonometric solution,the kink-lump interaction solution,the interaction solution between lump wave and triangular periodic wave,the two-kink solution,the lump solution,the interaction between a lump and two-kink and the periodic lump solution in different planes.These exact solutions are also given graphically to show the detailed structures of this high dimensional integrable system. 展开更多
关键词 extended(3+1)-dimensional KP-Boussinesq equation Lie group method similarity reduction invariant solution
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Dynamics of Nonlinear Waves in(2+1)-Dimensional Extended Boiti-Leon-Manna-Pempinelli Equation
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作者 SUN Junxiu WANG Yunhu 《应用数学》 北大核心 2024年第4期1103-1113,共11页
Based on the Hirota bilinear method,this study derived N-soliton solutions,breather solutions,lump solutions and interaction solutions for the(2+1)-dimensional extended Boiti-Leon-Manna-Pempinelli equation.The dynamic... Based on the Hirota bilinear method,this study derived N-soliton solutions,breather solutions,lump solutions and interaction solutions for the(2+1)-dimensional extended Boiti-Leon-Manna-Pempinelli equation.The dynamical characteristics of these solutions were displayed through graphical,particularly revealing fusion and ssion phenomena in the interaction of lump and the one-stripe soliton. 展开更多
关键词 Hirota bilinear method N-soliton solutions Breather solutions Lump solutions Interaction solutions (2+1)-dimensional extended Boiti-Leon-Manna-Pempinelli equation
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Hyper Catastrophe on 4-Dimensional Canards
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作者 Kiyoyuki Tchizawa Shuya Kanagawa 《Advances in Pure Mathematics》 2024年第4期196-203,共8页
When discovering the potential of canards flying in 4-dimensional slow-fast system with a bifurcation parameter, the key notion “symmetry” plays an important role. It is of one parameter on slow vector field. Then, ... When discovering the potential of canards flying in 4-dimensional slow-fast system with a bifurcation parameter, the key notion “symmetry” plays an important role. It is of one parameter on slow vector field. Then, it should be determined to introduce parameters to all slow/fast vectors. It is, however, there might be no way to explore for another potential in this system, because the geometrical structure is quite different from the system with one parameter. Even in this system, the “symmetry” is also useful to obtain the potentials classified by R. Thom. In this paper, via the coordinates changing, the possible way to explore for the potential will be shown. As it is analyzed on “hyper finite time line”, or done by using “non-standard analysis”, it is called “Hyper Catastrophe”. In the slow-fast system which includes a very small parameter , it is difficult to do precise analysis. Thus, it is useful to get the orbits as a singular limit. When trying to do simulations, it is also faced with difficulty due to singularity. Using very small time intervals corresponding small , we shall overcome the difficulty, because the difference equation on the small time interval adopts the standard differential equation. These small intervals are defined on hyper finite number N, which is nonstandard. As and the intervals are linked to use 1/N, the simulation should be done exactly. 展开更多
关键词 Canards Flying 4-dimensional Slow-Fast System Hyper Catastrophe
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Multiverse/Hyperverse Models: (4 + 1)-Dimensional Landscape (Black Saturns, Bousso-Hawking Nucleation, Gogberashvili Multiverses, Schwarzschild-De Sitter Nurseries) and a (3 + 1)-Dimensional Model for Dark Energy
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作者 Igor Yu. Potemine Werner Krause 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第4期1866-1877,共12页
We consider the Hyperverse as a collection of multiverses in a (4 + 1)-dimensional spacetime with gravitational constant G. Multiverses in our model are bouquets of thin shells (with synchronized intrinsic times). If ... We consider the Hyperverse as a collection of multiverses in a (4 + 1)-dimensional spacetime with gravitational constant G. Multiverses in our model are bouquets of thin shells (with synchronized intrinsic times). If gis the gravitational constant of a shell Sand εits thickness, then G~εg. The physical universe is supposed to be one of those thin shells inside the local bouquet called Local Multiverse. Other remarkable objects of the Hyperverse are supposed to be black holes, black lenses, black rings and (generalized) Black Saturns. In addition, Schwarzschild-de Sitter multiversal nurseries can be hidden inside those Black Saturns, leading to their Bousso-Hawking nucleation. It also suggests that black holes in our physical universe might harbor embedded (2 + 1)-dimensional multiverses. This is compatible with outstanding ideas and results of Bekenstein, Hawking-Vaz and Corda about “black holes as atoms” and the condensation of matter on “apparent horizons”. It allows us to formulate conjecture 12.1 about the origin of the Local Multiverse. As an alternative model, we examine spacetime warping of our universe by external universes. It gives data for the accelerated expansion and the cosmological constant Λ, which are in agreement with observation, thus opening a possibility for verification of the multiverse model. 展开更多
关键词 5-dimensional Gravity Black Hole Black Saturn Cosmological Constant Dark Energy MULTIVERSE Spacetime Warping Thin Shell
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Bifurcations, Analytical and Non-Analytical Traveling Wave Solutions of (2 + 1)-Dimensional Nonlinear Dispersive Boussinesq Equation
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作者 Dahe Feng Jibin Li Airen Zhou 《Applied Mathematics》 2024年第8期543-567,共25页
For the (2 + 1)-dimensional nonlinear dispersive Boussinesq equation, by using the bifurcation theory of planar dynamical systems to study its corresponding traveling wave system, the bifurcations and phase portraits ... For the (2 + 1)-dimensional nonlinear dispersive Boussinesq equation, by using the bifurcation theory of planar dynamical systems to study its corresponding traveling wave system, the bifurcations and phase portraits of the regular system are obtained. Under different parametric conditions, various sufficient conditions to guarantee the existence of analytical and non-analytical solutions of the singular system are given by using singular traveling wave theory. For certain special cases, some explicit and exact parametric representations of traveling wave solutions are derived such as analytical periodic waves and non-analytical periodic cusp waves. Further, two-dimensional wave plots of analytical periodic solutions and non-analytical periodic cusp wave solutions are drawn to visualize the dynamics of the equation. 展开更多
关键词 (2 + 1)-dimensional Nonlinear Dispersive Boussinesq Equation BIFURCATIONS Phase Portrait Analytical Periodic Wave Solution Periodic Cusp Wave Solution
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Hydrothermal Synthesis and Structure of a Novel Two-dimensional Complex:[Ni_(0.5)(H_2O)_(1.5){Ni(en)_2}_3V_(18)O_(42)(Cl)]3.5H_2O
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作者 郑寿添 杨国昱 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2004年第3期252-256,共5页
A novel two-dimensional compound [Ni0.5(H2O)1.5{Ni(en)2}3V18O42(Cl)]3.5H2O 1 has been hydrothermally synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction analysis. Crystal data... A novel two-dimensional compound [Ni0.5(H2O)1.5{Ni(en)2}3V18O42(Cl)]3.5H2O 1 has been hydrothermally synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction analysis. Crystal data for 1: monoclinic, space group C2/c with a = 12.824(3), b = 27.873(6), c = 21.092(4) , b = 92.93(3), V = 7529(3) 3, Z = 4, Dc = 2.012 g/cm3, Mr = 2280.56, F(000) = 4476 and m = 3.092 mm-1. The final R and wR are 0.0769 and 0.1783, respectively for 4203 observed reflections with I>2s(I). The structure consists of [V18O42(Cl)]7- clusters linked by trans- {Ni(en)2} groups into linear chains, while cis-{Ni(en)2} groups provide the cross-linking adjacent chains to form a two-dimensional structure. 展开更多
关键词 hydrothermal synthesis POLYOXOVANADATE crystal structure vanadium cluster nickel
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低排放情景下全球极端气候事件变化在温升过冲前后达到1.5℃的差异 被引量:1
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作者 徐影 韩振宇 +1 位作者 吴婕 李柔珂 《气候变化研究进展》 CSCD 北大核心 2024年第4期389-402,共14页
基于耦合模式比较计划第六阶段(CMIP6)全球气候模式在SSP1-1.9温室气体排放情景下的模拟结果,预估了全球平均气温相对于工业化前达到1.5℃温升(P1阶段)后继续增暖然后再次返回(过冲)到1.5℃温升时的(P2阶段)全球气温、降水及极端气候指... 基于耦合模式比较计划第六阶段(CMIP6)全球气候模式在SSP1-1.9温室气体排放情景下的模拟结果,预估了全球平均气温相对于工业化前达到1.5℃温升(P1阶段)后继续增暖然后再次返回(过冲)到1.5℃温升时的(P2阶段)全球气温、降水及极端气候指数的可能变化,并且分析其预估不确定性。结果表明:P1和P2两阶段间气温、降水及极端气候的多模式一致的差异在全球各分区广泛出现,且区域性和局地性特征明显。各指标表征的多模式一致的极端温度变化普遍接近或者超过全球陆地面积的15%。极端低温的P1和P2两阶段差异的空间分布与冬季平均气温差异的空间分布有一定相似度,极端高温变化的分布则更凸显局地性。全球范围内低温和高温多模式一致增加的面积都高于其减少的面积,预计欧亚大陆中高纬的西部、北美洲、中国东北等区域的低温风险以及青藏高原、中国东部、南亚、东非、北美洲、南极洲等区域的高温风险会升高。各指标表征的多模式一致的极端降水变化普遍超过全球陆地面积的20%,其中增加与减少的面积接近。强降水差异的分布特征与年降水的有部分相似,一致增多主要分布在中国南方、南亚、东南亚、南美洲东部和西南端、北美、澳洲和中东欧的部分地区等,一致减少主要分布在中国华北到东北、青藏高原南麓、非洲南部、南美洲北部和澳洲北部等。连续干旱日数在多数区域表现为增多,集中且连续地分布在中亚、南亚、青藏高原、俄罗斯中北部、非洲撒哈拉以北和中部、澳洲中部、南极洲部分地区等。这些都表明即使全球在2030年前达到碳排放峰值,并立即开始减少碳排放,但由于各个区域气候对全球变暖的响应有明显差异,温升过冲后部分区域的极端事件发生频率并未及时回退到过冲前的水平,需警惕区域和局地尺度气象灾害及其影响的增加。 展开更多
关键词 1.5℃温升 过冲 极端气候 预估
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原子层沉积Al_(2)O_(3)对尖晶石LiNi_(0.5)Mn_(1.5)O_(4)正极材料的影响机理
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作者 李倩 赵妍 +8 位作者 崔雅茹 王硕然 黄娜 李常林 王文培 马红周 杜金晶 何喜红 翁雅青 《矿冶工程》 CAS 北大核心 2024年第4期8-12,共5页
为提升尖晶石相LiNi_(0.5)Mn_(1.5)O_(4)正极材料在深度荷电状态下的界面稳定性,采用原子层沉积法在单晶LiNi_(0.5)Mn_(1.5)O_(4)正极材料表面可控沉积了纳米级Al_(2)O_(3)层。改性后的LiNi_(0.5)Mn_(1.5)O_(4)正极材料表现出优异的长... 为提升尖晶石相LiNi_(0.5)Mn_(1.5)O_(4)正极材料在深度荷电状态下的界面稳定性,采用原子层沉积法在单晶LiNi_(0.5)Mn_(1.5)O_(4)正极材料表面可控沉积了纳米级Al_(2)O_(3)层。改性后的LiNi_(0.5)Mn_(1.5)O_(4)正极材料表现出优异的长循环耐腐蚀性能(1C电流密度下循环500次的容量保持率高达94.7%)。进一步的表界面解析结果表明:原子层沉积技术构建的纳米级Al_(2)O_(3)包覆层能够明显抑制材料本体与电解液的腐蚀反应,降低过渡金属离子的不可逆溶解与析出;另外,基于HF表面刻蚀产生的AlF_(3)具有增强的耐刻蚀性能,可显著提升LiNi_(0.5)Mn_(1.5)O_(4)正极材料在长循环及高电压下的服役性能。 展开更多
关键词 锂离子电池 LiNi_(0.5)Mn_(1.5)O_(4) 正极材料 原子层沉积 Al_(2)O_(3) 表面改性
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硅含量对9Cr-1.5W钢在550℃下蠕变性能的影响
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作者 何琨 陈乐 李刚 《机械工程材料》 CAS CSCD 北大核心 2024年第1期60-65,共6页
在550℃下对硅质量分数分别为0.34%,0.60%,0.90%的9Cr-1.5W钢进行拉伸试验以及不同应力下的蠕变试验,研究了硅含量对试验钢高温拉伸性能和蠕变性能的影响。结果表明:随着硅含量的增加,试验钢在550℃下的屈服强度和抗拉强度均降低,但断... 在550℃下对硅质量分数分别为0.34%,0.60%,0.90%的9Cr-1.5W钢进行拉伸试验以及不同应力下的蠕变试验,研究了硅含量对试验钢高温拉伸性能和蠕变性能的影响。结果表明:随着硅含量的增加,试验钢在550℃下的屈服强度和抗拉强度均降低,但断后伸长率增大,应变硬化指数先升后降,含质量分数0.60%硅的试验钢具有最大的应变硬化指数;含质量分数0.60%硅的试验钢在不同应力下均具有较长的蠕变时间,表现出最佳的高温蠕变性能,应力指数最小,最小蠕变速率对外加应力敏感性最低;试验钢的蠕变行为均受位错攀移控制。 展开更多
关键词 9Cr-1.5W钢 高温蠕变 硅元素 铁素体相
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1.5T磁共振胰胆管成像与腹部CT在胆囊结石中的诊断价值分析 被引量:1
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作者 石凯 刘东升 《临床医学工程》 2024年第1期5-6,共2页
目的探讨1.5T磁共振胰胆管成像与腹部CT在胆囊结石中的诊断价值。方法选取2020年9月至2023年3月我院收治的200例疑似胆囊结石患者,应用1.5T磁共振胰胆管成像与腹部CT检查。以手术病理检查结果为金标准,分析两种检查方式对胆囊结石诊断... 目的探讨1.5T磁共振胰胆管成像与腹部CT在胆囊结石中的诊断价值。方法选取2020年9月至2023年3月我院收治的200例疑似胆囊结石患者,应用1.5T磁共振胰胆管成像与腹部CT检查。以手术病理检查结果为金标准,分析两种检查方式对胆囊结石诊断结果的一致性,比较其诊断效能。结果200例疑似胆囊结石患者经手术病理检查确诊为胆囊结石183例,检出率为91.5%。κ检验分析结果显示,腹部CT检查结果与手术病理检查结果具有一般的一致性(κ=0.643,P<0.05);磁共振胰胆管成像检查结果与手术病理检查结果具有较高的一致性(κ=0.904,P<0.05)。磁共振胰胆管成像诊断胆囊结石的灵敏度、特异度与准确度均高于腹部CT(P<0.05)。结论与腹部CT相比,1.5T磁共振胰胆管成像诊断胆囊结石的准确度更高,可为医师后续治疗方案的制定提供更加可靠的数据参考,应用价值显著。 展开更多
关键词 1.5T磁共振胰胆管成像 腹部CT 胆囊结石 诊断效能
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固溶处理对Mg-1.5Er-1.0Zn-0.3Zr合金组织和性能的影响
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作者 贺俊光 冯武云 +2 位作者 文九巴 龚圆 郑向阳 《材料热处理学报》 CAS CSCD 北大核心 2024年第9期124-133,共10页
采用光学显微镜(OM)、扫描电镜(SEM)、电化学实验和拉伸实验等研究固溶处理对Mg-1.5Er-1.0Zn-0.3Zr合金组织、耐蚀性能和力学性能的影响。结果表明:铸态合金的显微组织主要由α-Mg基体、Mg_(3)Er_(2)Zn_(3)、Mg_(24)Er_(5)和MgErZn_(2)... 采用光学显微镜(OM)、扫描电镜(SEM)、电化学实验和拉伸实验等研究固溶处理对Mg-1.5Er-1.0Zn-0.3Zr合金组织、耐蚀性能和力学性能的影响。结果表明:铸态合金的显微组织主要由α-Mg基体、Mg_(3)Er_(2)Zn_(3)、Mg_(24)Er_(5)和MgErZn_(2)相组成。经固溶处理后,第二相逐渐溶解在镁基体中,且合金平均晶粒尺寸有不同程度的增大。合金经460℃固溶处理8 h后的综合性能较好,其腐蚀速率为(0.44±0.051)mm/y,抗拉强度、屈服强度和伸长率分别为(227.97±4.84)MPa、(137.96±5.03)MPa和(14.42±1.06)%。 展开更多
关键词 Mg-1.5Er-1.0Zn-0.3Zr合金 固溶处理 腐蚀性能
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Al-12.0Si-4.0Cu-0.7Mg-1.5Ni合金固溶处理工艺研究
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作者 王勇 罗新民 《热加工工艺》 北大核心 2024年第16期45-48,52,共5页
对铸态Al-12.0Si-4.0Cu-0.7Mg-1.5Ni合金进行了双级固溶+时效处理,采用SEM、XRD、硬度测试等研究了双级固溶中第二级固溶温度和时间对铸态合金组织与硬度的影响。结果表明:铸态Al-12.0Si-4.0Cu-0.7Mg-1.5Ni合金组织主要由α-Al固溶体、... 对铸态Al-12.0Si-4.0Cu-0.7Mg-1.5Ni合金进行了双级固溶+时效处理,采用SEM、XRD、硬度测试等研究了双级固溶中第二级固溶温度和时间对铸态合金组织与硬度的影响。结果表明:铸态Al-12.0Si-4.0Cu-0.7Mg-1.5Ni合金组织主要由α-Al固溶体、块状初生Si相、针状共晶Si相以及网状第二相组成。经过双级固溶处理后,合金中块状初生Si相明显钝化,共晶Si相明显细化,网状第二相也显著碎化。490℃×2 h+525℃×4 h双级固溶处理合金中网状相基本完全碎化,共晶Si相最为细小。随着双级固溶中第二级固溶温度的提高,固溶时间的延长,T6态Al-12.0Si-4.0Cu-0.7Mg-1.5Ni合金的硬度先升高后降低,490℃×2 h+525℃×4 h双级固溶+180℃×6 h时效处理合金的硬度最高,达到88.2 HRB。 展开更多
关键词 Al-12.0Si-4.0Cu-0.7Mg-1.5Ni合金 固溶处理 组织 硬度
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1.5T磁共振动态对比增强(DCE-MRI)技术联合表观弥散系数(ADC)值对乳腺肿块样强化病变良恶性的鉴别诊断价值
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作者 龙敏 王跃斌 《延边大学医学学报》 CAS 2024年第3期289-292,共4页
目的:分析1.5T磁共振动态对比增强(DCE-MRI)技术联合表观弥散系数(ADC)值对乳腺肿块样强化病变良恶性的鉴别诊断价值。方法:选取2021年10月至2024年4月在三明市第二医院治疗的163例乳腺肿块样强化病变患者的临床资料进行回顾性分析。选... 目的:分析1.5T磁共振动态对比增强(DCE-MRI)技术联合表观弥散系数(ADC)值对乳腺肿块样强化病变良恶性的鉴别诊断价值。方法:选取2021年10月至2024年4月在三明市第二医院治疗的163例乳腺肿块样强化病变患者的临床资料进行回顾性分析。选取的患者均接受1.5T DCE-MRI检查。根据强化方式、时间-信号强度(TIC)曲线、病灶形态、病灶边界,计算ADC值。以病理诊断结果为金标准,以1.5T DCE-MRI诊断结果为对照1组,以ADC诊断结果为对照2组,以联合诊断结果为观察组。对比三种诊断方式在乳腺肿块样强化病良恶性鉴别诊断中的应用价值。结果:以病理诊断结果为金标准,对比对照1组与对照2组的各项诊断效能指标,差异无统计学意义(P>0.05)。观察组的各项诊断效能指标均明显优于对照1组以及对照2组,差异具有统计学意义(P<0.05)。结论:在乳腺肿块样强化病变良恶性的鉴别诊断中,应用1.5T DCE-MRI联合ADC值具有更高的诊断效能,临床应用价值显著。 展开更多
关键词 乳腺肿块样强化病变 1.5T磁共振动态对比增强技术 表观弥散系数值
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Exotic Localized Coherent Structures of New (2+1)-Dimensional Soliton Equation 被引量:8
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作者 ZHANG Jie-Fang HUANG Wen-Hua ZHENG Chun-Long 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第11期517-522,共6页
The variable separation approach is used to obtain localized coherent structures of the new (2+1)-dimensional nonlinear partialdifferential equation. Applying the Backlund transformation and introducing the arbitraryf... The variable separation approach is used to obtain localized coherent structures of the new (2+1)-dimensional nonlinear partialdifferential equation. Applying the Backlund transformation and introducing the arbitraryfunctions of the seed solutions, the abundance of the localized structures of this model are derived. Some special types ofsolutions solitoff, dromions, dromion lattice, breathers and instantons are discussed by selecting the arbitrary functionsappropriately. The breathers may breath in their amplititudes, shapes, distances among the peaks and even the numberof the peaks. 展开更多
关键词 variable separation approach coherent structures NEW (2+1)-dimensional SOLITON equation
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A Variable Separation Approach to Solve the Integrable and Nonintegrable Models:Coherent Structures of the (2 + 1)-Dimensional KdV Eqnation 被引量:8
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作者 TANG Xiao-Yan LOU Sen-Yue 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第7期1-8,共8页
We study the localized coherent structures ofa generally nonintegrable (2+ 1 )-dimensional KdV equation via a variable separation approach. In a special integrable case, the entrance of some arbitrary functions leads ... We study the localized coherent structures ofa generally nonintegrable (2+ 1 )-dimensional KdV equation via a variable separation approach. In a special integrable case, the entrance of some arbitrary functions leads to abundant coherent structures. However, in the general nonintegrable case, an additional condition has to be introduced for these arbitrary functions. Although the additional condition has been introduced into the solutions of the nonintegrable KdV equation, there still exist many interesting solitary wave structures. Especially, the nonintegrable KdV equation possesses the breather-like localized excitations, and the similar static ring soliton solutions as in the integrable case. Furthermor,in the integrable case, the interaction between two travelling ring solitons is elastic, while in the nonintegrable case we cannot find even the single travelling ring soliton solution. 展开更多
关键词 variable SEPARATION approach INTEGRABLE and nonintegrable models (2+1)-dimensional SOLITONS
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Role of 2-dimensional Doppler echo-cardiography in screening portopulmonary hypertension in portal hypertension patients 被引量:7
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作者 Hua, Rong Sun, Yong-Wei +4 位作者 Wu, Zhi-Yong Cheng, Wei Xu, Qing Cao, Hui Luo, Meng 《Hepatobiliary & Pancreatic Diseases International》 SCIE CAS 2009年第2期157-161,共5页
BACKGROUND: Portopulmonary hypertension (PPH) is difficult to recognize in the early and middle stages because it is frequently asymptomatic. As right ventricular function is impaired in patients with moderate and sev... BACKGROUND: Portopulmonary hypertension (PPH) is difficult to recognize in the early and middle stages because it is frequently asymptomatic. As right ventricular function is impaired in patients with moderate and severe PPH, any dramatic hemodynamic changes in liver transplantation or other procedures may result in death from pulmonary and cardiac events. In this study, we investigated the prevalence of PPH in patients with portal hypertension (PHT) mainly caused by hepatitis B virus, and evaluated the effect of 2-dimensional Doppler echocardiography (2D-ECHO) in screening for PPH. METHODS: One hundred and five PHT patients received transthoracic 2D-ECHO preoperatively, systolic pulmonary arterial pressure (SPAP, normal range <30 mmHg) and pulmonary acceleration time (PAT, normal range >= 120 msec) were measured to screen for PPH (positive result: SPAP >= 30 mmHg and/or PAT <100 msec). Subsequently, pulmonary hemodynamic parameters were measured by right heart catheterization (RHC) for definitive diagnosis of PPH. The results of the two methods were compared to assess the screening effect of 2D-ECHO. RESULTS: The prevalence of PPH in this study was 3.8% (4/105). About 90% (95/105) of patients had a detectable tricuspid regurgitation by 2D-ECHO and the mean SPAP was 27.7 +/- 5.9 mmHg. Twenty-two of these 95 patients had an SPAP >30 mmHg. The mean PAT of all patients was 140 23 msec and 5 were <100 msec. Twenty-two patients were screened out by 2D-ECHO and 4 were diagnosed by RHC. A positive significant correlation (r=0.55, P<0.01) was found between SPAP measured by 2D-ECHO and mean pulmonary artery pressure (MPAP) measured by RHC, and a weak but significant negative correlation (r=-0.27, P=0.005) existed between PAT and pulmonary vascular resistance (PVR). The sensitivity, specificity, agreement rate, positive predictive value and negative predictive value of the screening test were 100%, 82%, 83%, 18% and 100%, respectively. CONCLUSIONS: The prevalence of PPH in this study is lower than in Western countries. As a screening test, 2D-ECHO has very high sensitivity and negative predictive value. A negative test result can directly be used to exclude PPH, while a positive result should be confirmed by RHC. 展开更多
关键词 portopulmonary hypertension 2-dimensional Doppler echocardiography right heart catheterization PREVALENCE diagnosis
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A 3-DIMENSIONAL DATA MODEL FOR VISUALIZING CLOVERLEAF JUNCTION IN A CITY MODEL 被引量:6
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作者 Chen Jun Sun Min Zhou Qiming 《Geo-Spatial Information Science》 1999年第1期9-15,共7页
The research work has been seldom done about cloverleaf junction expression in a 3-dimensional city model (3DCM). The main reason is that the cloverleaf junction is often in a complex and enormous construction. Its ma... The research work has been seldom done about cloverleaf junction expression in a 3-dimensional city model (3DCM). The main reason is that the cloverleaf junction is often in a complex and enormous construction. Its main body is bestraddle in air,and has aerial intersections between its parts. This complex feature made cloverleaf junction quite different from buildings and terrain, therefore, it is difficult to express this kind of spatial objects in the same way as for buildings and terrain. In this paper,authors analyze spatial characteristics of cloverleaf junction, propose an all-constraint points TIN algorithm to partition cloverleaf junction road surface, and develop a method to visualize cloverleaf junction road surface using TIN. In order to manage cloverleaf junction data efficiently, the authors also analyzed the mechanism of 3DCM data management, extended BLOB type in relational database, and combined R-tree index to manage 3D spatial data. Based on this extension, an appropriate data 展开更多
关键词 3-dimensional CITY model (3DCM) GIS cloverleaf JUNCTION DATA STRUCTURE DATABASE
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1.5T磁共振-SWI序列对高血压性脑微出血的诊断价值分析
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作者 马玉萍 《中国科技期刊数据库 医药》 2024年第5期0017-0020,共4页
观察1.5T磁共振-SWI序列在高血压性脑微出血中的诊断价值。方法 选取本院2022年8月-2023年8月期间,经诊断已确诊的40例原发性高血压患者作为此次研究对象,均行1.5T磁共振-SWI序列与常规MRI诊断,分析诊断结果。结果 经分析,1.5T磁共振-SW... 观察1.5T磁共振-SWI序列在高血压性脑微出血中的诊断价值。方法 选取本院2022年8月-2023年8月期间,经诊断已确诊的40例原发性高血压患者作为此次研究对象,均行1.5T磁共振-SWI序列与常规MRI诊断,分析诊断结果。结果 经分析,1.5T磁共振-SWI序列在病灶数目、特征上,较常规 MRI诊断更优;对比两种诊断方式的检出率,1.5T磁共振-SWI序列为100%,显著高于常规MRI诊断的87.5%,差异有统计学意义(P<0.05)。结论 在高血压性脑微出血的诊断中,应用1.5T磁共振-SWI序列,具有不错的诊断价值,病灶检出率高,能够为后续临床方案的制定提供数据参考。 展开更多
关键词 1.5T磁共振-SWI序列 高血压 脑微出血 诊断效果
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1.5T磁共振磁敏感成像在脑出血性病变中的诊断价值
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作者 李颖 《中国科技期刊数据库 医药》 2024年第8期0052-0055,共4页
探讨基于临床脑出血性病变患者,进行1.5T磁共振磁敏感成像检查,分析其诊断价值。方法 研究开始于2023年1月,截止时间则为2023年12月,挑选南京市溧水区中医院50例有出血性疾病的患者为阅览目标,所有相关病员都在接受1.5T磁共振磁敏感成... 探讨基于临床脑出血性病变患者,进行1.5T磁共振磁敏感成像检查,分析其诊断价值。方法 研究开始于2023年1月,截止时间则为2023年12月,挑选南京市溧水区中医院50例有出血性疾病的患者为阅览目标,所有相关病员都在接受1.5T磁共振磁敏感成像检查(SWI)事宜、常规序列扫描(T1WI\T2WI\FLAIR)事宜,比拟各种扫描方式对出血灶检测状况,影像特点和出血缘由辨析,呈现1.5T磁共振磁敏感成像检查下的出血灶测量水平参考值、微出血灶测量水平参考值、出血面积测量水平参考值、出血量测量水平参考值均高于常规序列扫描的数据(P<0.05)。SWI下,脑部出血的影像学特征主要表现为片状、斑点状、边缘清楚,血肿面积比常规序列扫描更大、更为清晰。显示1.5T磁共振磁敏感成像检查对特殊病因的检出率明显高于常规序列扫描(P<0.05)。结论 1.5T磁敏成像技术在临床上用于脑出血的诊断,比常规序列扫描有更大的优点,得到较高的可行性,增加了出血病变的检出率,利于对出血面积、出血量进行评估,对于出血病因分析更为全面,为临床诊断治疗提供可靠依据。 展开更多
关键词 脑出血性病变 1.5T磁共振磁敏感成像 诊断价值
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