On Differential Equations Describing 3-Dimensional Hyperbolic Spaces

In this paper, we introduce the notion of a （2＋1）-dimenslonal differential equation describing three-dimensional hyperbolic spaces （3-h.s.）. The （2＋1）-dimensional coupled nonlinear Schrodinger equation and its sister equation, the （2＋1）-dimensional coupled derivative nonlinear Schrodinger equation, are shown to describe 3-h.s, The （2 ＋ 1 ）-dimensional generalized HF model：St=（1/2i[S,Sy]＋2iσS）x,σx=-1/4i tr（SSxSy）, in which S ∈ GLc（2）/GLc（1）×GLc（1）,provides another example of （2＋1）-dimensional differential equations describing 3-h.s. As a direct con-sequence, the geometric construction of an infinire number of conservation lairs of such equations is illustrated. Furthermore we display a new infinite number of conservation lairs of the （2＋1）-dimensional nonlinear Schrodinger equation and the （2＋1）-dimensional derivative nonlinear Schrodinger equation by a geometric way.

3D MERGE与3D SPACE STIR序列在腰椎间盘突出症检查中的应用比较

目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,所有患者均接受常规MRI扫描及3D MERGE、3D SPACE STIR序列扫描,对比3D MERGE、3D SPACE STIR序列测量神经根直径的一致性,评价两种序列的图像质量参数[信噪比(SNR)、对比噪声比(CNR)]、图像清晰度评分。结果:3D MERGE和3D SPACE STIR序列测量的L3~S1神经根直径比较差异无统计学意义(P>0.05),且两组序列测量的L3、L4、L5和S1直径均显示出较高相关性(r=0.957,0.986,0.975,0.972,P<0.05);3D MERGE序列的SNR及CNR均高于3D SPACE STIR序列,神经根显示分级、图像清晰度评分优于3D SPACE STIR序列,差异有统计学意义(P<0.05)。结论:3D MERGE、3D SPACE STIR序列在LDH神经根直径测量中具有极高一致性,3D MERGE序列较3D SPACE STIR序列能够更清晰显示神经跟的解剖形态,图像质量更好。

MR3D-STIR SPACE序列增强扫描在臂丛节后神经成像的效果分析

目的探讨在臂丛节后神经成像中施行MR3D-STIR SPACE序列增强扫描的临床价值及成像质量。方法选取50例、2021年1月-2022年8月臂丛神经患者,均行MR常规序列扫描、MR3D-SPACE-STIR序列平扫及增强扫描。对患者的损伤部位、形态、信号强度与近、远侧段臂丛神经的相关性,并对比平扫及增强图像质量。结果MRI平扫诊断节后神经损伤敏感性为89.47%、特异性为83.33%、准确性88.64%。增强MR3D-SPACE-STIR的组织对比显著提高,经处理后,可对臂丛神经节后的走行图像进行完整显示。且该技术增强序列图像的对比噪声比(CNR)为(0.57±0.09)、背景抑制评分(3.56±0.63)分及对臂丛神经显示评分(3.96±0.53)与平扫(0.35±0.06)、(1.58±0.51)分、(2.02±0.59)分均存在显著差异(t=12.231,12.214,10.170;P<0.05)。结论MR 3D-SPACE-STIR序列增强扫描的背景抑制效果较佳,可使臂丛神经损伤及走形得以清晰显示,其臂丛神经节后图像质量较平扫明显提升。

3D printing in space:from mechanical structures to living tissues

3D printing stands at the forefront of transforming space exploration,offering unprecedented on-demand and rapid manufacturing capabilities.It adeptly addresses challenges such as mass reduction,intricate component fabrication,and resource constraints.Despite the obstacles posed by microgravity and extreme environments,continual advancements underscore the pivotal role of 3D printing in aerospace science.Beyond its primary function of producing space structures,3D printing contributes significantly to progress in electronics,biomedicine,and resource optimization.This perspective delves into the technological advantages,environmental challenges,development status,and opportunities of 3D printing in space.Envisioning its crucial impact,we anticipate that 3D printing will unlock innovative solutions,reshape manufacturing practices,and foster self-sufficiency in future space endeavors.

Benchmarking of two three-dimensional numerical models in time/space domain to predict railway-induced ground vibrations

In the last 30 years,the scientific community has developed and proposed different models and numerical approaches for the study of vibrations induced by railway traffic.Most of them are formulated in the frequency/wave number domain and with a 2.5D approach.Three-dimensional numerical models formulated in the time/space domain are less frequently used,mainly due to their high computational cost.Notwithstanding,these models present very attractive characteristics,such as the possibility of considering nonlinear behaviors or the modelling of excess pore pressure and non-homogeneous and non-periodic geometries in the longitudinal direction of the track.In this study,two 3D numerical approaches formulated in the time/space domain are compared and experimentally validated.The first one consists of a finite element approach and the second one of a finite difference approach.The experimental validation in an actual case situated in Carregado(Portugal)shows an acceptable fitting between the numerical results and the actual measurements for both models.However,there are some differences among them.This study therefore includes some recommendations for their use in practical soil dynamics and geotechnical engineering.

国内外3~6岁幼儿语言能力发展的相关研究——基于Cite Space的可视化分析

本文以3~6岁幼儿语言能力发展为主题,采用Cite Space软件分别以关键词、年发文量、核心作者、核心机构等为关键词,对中国知网收录的31篇文章和Web Of Science收录的130篇文章导出相关内容图谱进行可视化分析。基于此,本文建议通过加强幼儿语言教育相关政策体系的建设,促进家长及幼儿园教师对幼儿语言发展的策略、加大幼儿语言教育的宣传等,来提升幼儿语言能力的发展。

A new method of mesh simplification for 3-Dimension terrain using Laplace operator

This paper proposes a new method to simplify mesh in 3D terrain. The 3D terrain is presented by digital elevation model. First, Laplace operator is introduced to calculate sharp degree of mesh point, which indicates the variation trend of the terrain. Through setting a critical value of sharp degree, feature points are selected. Second, critical mesh points are extracted by an recursive process, and constitute the simplified mesh. Third, the algorithm of linear-square interpolation is employed to restore the characteris- tics of the terrain. Last, the terrain is rendered with color and texture. The experimental results demonstrate that this method can compress data by 16% and the error is lower than 10%.

Three-dimensional numerical simulation of geothermal fi eld in space-wavenumber domain

Large-scale,fine,and efficient numerical simulation of a geothermal field plays an important role in geothermal energy development.Confronted with the problem of large computation and high storage requirements for complex underground models in a three-dimensional(3-D)numerical simulation of a geothermal fi eld,a mixed space-wavenumber domain 3-D numerical simulation algorithm is proposed in this paper.According to the superposition principle of temperature field,the geothermal field is decomposed into background and abnormal temperature fi elds for calculation.The uniform layered model is used to solve the background field.When the abnormal field is solved,the horizontal two-dimensional(2-D)Fourier transform is used to transform the 3-D diff erential equation satisfi ed by an abnormal field into a series of one-dimensional ordinary differential equations with diff erent wavenumbers,which greatly reduces the calculation and storage.The unit division of an ordinary diff erential equation is fl exible,and the calculation amount is small.The algorithm fully takes advantage of the effi ciency of the Fourier transform and the quickness of the catch-up method to solve linear equations with a fixed bandwidth,which effectively improves the computational efficiency.Compared with the COMSOL Multiphysics professional simulation finite element software,the time consumption and memory requirements of the algorithm proposed in this paper are reduced by multiple orders of magnitude in terms of ensuring accuracy and the same mesh division.The more the number of calculated nodes is,the more obvious is the advantage.We design models to study the thermal conductivity,heat fl ux boundary,regional tectonic morphology,and topographic relief of the geothermal fi eld distribution.A 3-D geophysical model is developed based on topographic elevation data,geothermal geology,and geophysical exploration data in the Qiabuqia area of Gonghe Basin,Qinghai Province,China.Numerical simulation of the geothermal fi eld in this area is realized,which shows that the algorithm is suitable for precise and effi cient simulation of an arbitrary complex terrain and geological conditions.

MR 3D FLASH-WE结合3D SPACE技术在颅神经疾病中的应用

目的:研究MR 3D FLASH-WE结合3D SPACE序列对颅神经疾病微血管减压术(MVD)指导价值。方法:106例经显微血管减压术治疗颅神经疾病患者。其中HFS(面肌痉挛)68例,TN(三叉神经痛)34例,GPN(舌咽神经痛)4例。术前均行常规磁共振及3D FLASH WE、3D SPACE、3D TOF序列检查。单独并联合应用以上序列分析颅神经与血管关系,并与手术结果对照。结果:3D FLASH-WE序列对面神经及三叉神经REZ(出脑干区)段的显示明显优于3D TOF序列,对其周围血管的显示与3D TOF序列差异无统计学意义;3D FLASH-WE结合3D SPACE序列较3D TOF结合3D SPACE序列显示神经与血管关系更清晰,对神经与血管是否存在接触的情况判断更准确,但与手术比较无明显差异(P<0.05)。结论:3D FLASH-WE结合3D SPACE序列能清晰显示颅神经与血管关系,准确判断责任血管,对显微血管减压术有重要的指导意义。

1.5T磁共振3D-SPACE序列与3D-TSERT序列在MRCP成像中的应用对比

目的:通过MR可变翻转角的三维快速自旋回波(3D sampling perfertion with application optimized contrasts using deifferent flip angle evolutions,3D-SPACE)序列与三维快速恢复快速自旋回波(3D-TSE Retore,3D-TSERT)序列对胰胆管水成像(MR cholangiopancreatgrapgy,MRCP)中的成像质量进行对比,优化MRCP的成像序列。方法:对48位受检者分别用3D-SPACE序列与3D-TSERT序列行MRCP检查,将采集到的影像利用siemens 3D软件进行MIP(maxium intensity projection)重建,并对2种图像的显示情况进行分析比较。结果:3D-SPACE序列的MRCP显示肝段胆管、胰管的效果明显优于3D-TSERT-MRCP序列(P﹤0.05),2种成像序列显示左右肝管、肝总管、胆囊、胆总管的效果差异无显著性意义(P>0.05)。结论:在1.5TMRI检查中,应用3D-SPACE序列的MRCP在检查时间及成像质量上都优于3D-TSE序列,应成为常规MRCP的首选序列。

3D MEDIC和3D SPACE磁共振神经成像在腰骶丛神经根的一致性对比研究

目的验证三维多回波数据联合成像(three dimensional multi-echo data imagine combination with selective water excitation,3D MEDIC WE)和三维快速自旋回波成像(three dimensional sampling perfection with application optimized contrasts by using different flip angle evolution,3D SPACE STIR)序列在腰骶丛神经根成像中的可行性和重复性。方法将55例受试者分为腰椎无异常表现的正常对照组(20例)、单纯性腰椎间盘突出症(lumbar disc herniation,LDH)组(20例)和慢性炎性脱髓鞘性多发性神经根神经病症(chronic inflammatory demyelinating polyradiculoneuropathy,CIDP)组(15例),分别应用两种腰骶丛神经根成像,评价图像质量参数信噪比(signal to noise ratio,SNR)、对比噪声比(contrast to noise ratio,CNR)和对比度(contrast ratio,CR),并验证正常对照组、CIDP组和LDH组测量神经根直径的一致性。结果两序列测得神经根直径的一致性较高(正常组r=0.95,CIDP组r=0.99,LDH组r=0.97,P<0.001),图像质量评价指标显示,3D SPACE STIR序列在SNR、CNR和CR三项指标中占优,3D MEDIC WE定性评估图像质量评分较高。两序列均能清晰显示正常腰骶丛神经根、病变所致的弥漫性形态增粗神经根以及间盘突出受挤压变形的神经根。结论3D MEDIC WE和3D SPACE STIR序列可应用于腰骶丛神经根成像,两序列对正常和异常形态、走行的神经根评估具备很高的可行性和重复性。综合考量临床图像的定性、定量评价,可择优选择恰当的序列为腰骶丛神经根成像提供影像支持。

3D SPACE STIR结合DTI显示腰骶神经根病变的研究

目的 探讨结合DTI的短回波反转恢复各向同性变换角度RF激发3DT2TSE序列（SPACE：Sampling Perfection with Application optimized Contrasts using different flip angle evolutions）在腰骶丛病变成像中的应用价值。方法10例健康志愿者和32例腰骶丛神经病变患者行常规扫描序列、3DSPACE STIR序列和DTI序列扫描。结果 10名健康自愿者,L1~S1腰骶神经根3DSPCACE STIR序列均得到清晰显示。32例腰骶丛神经病变中,神经根受推压移位27例,受侵犯5例。椎间盘突出所致神经根受损的FA值降低（P〈0.05）,而ADC值升高（P〈0.05）。结论 3DSPACE STIR序列具有较好的组织对比,图像可被作为测量DTI数据的FA值及ADC值的高分辨率蒙片,两者结合可以很好评估腰骶神经丛的神经压迫位置和神经受侵犯的范围和程度。

3D SPACE序列及后处理在显示大脑中动脉硬化中的临床价值

目的:探讨高分辨率MRI脑血管壁成像3D SPACE序列及后处理技术在显示大脑中动脉硬化中的价值。方法:对行MRI常规序列和3D SPACE序列检查、符合脑动脉硬化诊断标准的40例患者进行观察和分析。采用3D SPACE序列行冠状面T1WI-FS、T2WI-FS和T1WI-FS增强扫描、曲面重建(CPR),在CPR图像上行大脑中动脉的硬化斑块断面重建。分析动脉硬化斑块的以下MRI表现:病变数目、狭窄长度、断面血管形态、信号强度、强化程度、内膜的完整性。计算血管狭窄程度和测量增强的信号值。根据T2WI、DWI等表现等将患者分为急性脑梗死组(组1)、非急性脑梗死组(组2)和无脑梗死组(组3),比较各组病变MRI表现的差异。结果:40例患者CPR显示共61处位于大脑中动脉的硬化性病变。MRI表现为节段性或局限性狭窄,多为偏心性管壁增厚,T1WI和T2WI呈高、稍高或等信号,强化程度主要为明显、中度,血管内膜多不完整。急性脑梗死组(组1)19例,非急性脑梗死组(组2)11例,无脑梗死组(组3)10例。组1狭窄长度、T1WI-FS和T2WI-FS的信号强度、强化程度均高于组2和组3,组2、组3依次降低。急性脑梗死组的管腔狭窄程度为0.729±0.209,明显高于组2和组3(分别为0.482±0.232和0.406±0.194),差异有统计学意义(P<0.05)。3组增强的信号值分别为408.83±137.56、306.65±114.05、201.24±42.31,差异有统计学意义(P<0.05)。结论:3D SPACE序列及后处理技术显示大脑中动脉及其管壁硬化性病变具有一定优势,能显示动脉硬化斑块的多种MRI表现,且急性脑梗死、非急性脑梗死和无脑梗死患者各种MRI表现的严重程度也不相同,3D SPACE序列对大脑中动脉硬化性病变的显示具有一定价值。

对比增强3D STIR SPACE序列对子宫内膜异位症患者骶丛神经异常的显示

【目的】探讨增强3D STIR SPACE序列对盆腔子宫内膜异位症患者骶丛神经异常的显示价值,并与增强3D VIBE序列进行对比。【方法】病例组包括30名子宫内膜异位症患者,对照组包括20名健康女性,均接受盆腔MRI检查,包括对比增强3D STIR SPACE序列和增强3D VIBE序列。评估骶丛神经显示的图像质量以及子宫内膜异位症患者中的骶丛神经侵犯。【结果】对照组和病例组中,3D STIR SPACE序列和3D VIBE序列均能很好地显示骶丛神经纤维(P<0.001)。阅片者应用3D-STIR-SPACE序列对病变的诊断信心分数一致性较强(Kappa=0.684,P<0.001),应用3D-VIBE序列的诊断信心分数一致性一般(Kappa=0.130,P=0.386)。【结论】对比增强T2-SPACE序列和3D VIBE序列能够清晰显示骶丛神经,前者对盆腔子宫内膜异位症患者骶丛神经异常的显示更有优势。

2D TSE与3D SPACE序列对直肠癌术前T分期的诊断价值比较

目的比较三维可变翻转角各向同性快速自旋回波(3D SPACE)序列与传统二维快速自旋回波(2D TSE)序列对直肠癌术前T分期的诊断价值。资料与方法选取2018年1月—2019年12月青岛大学附属医院收治的直肠癌患者75例,术前进行2D TSE及3D SPACE序列扫描,计算2D TSE及3D SPACE序列图像的信噪比(SNR)、对比噪声及图像评分评估图像质量。以术后病理结果为“金标准”,比较2D TSE及3D SPACE序列诊断直肠癌术前T分期的准确度。结果2D TSE和3D SPACE序列的图像质量在显示直肠浆膜层或外膜[3.00(2.00,3.00)比3.00(3.00,3.00);Z=−0.16,P=0.990]、肠周脂肪[3.00(3.00,3.00)比3.00(3.00,3.00);Z=−0.259,P=0.800]、直肠系膜筋膜[3.00(3.00,3.00)比3.00(3.00,3.00);Z=−1.27,P=0.210]、瘤体[3.00(3.00,3.00)比3.00(3.00,3.00);Z=−0.03,P=0.990]比较,差异无统计学意义。3D SPACE序列在显示直肠黏膜层[3.00(2.00,3.00)比3.00(3.00,3.00);Z=−2.47,P=0.013]、直肠肌层[3.00(2.00,3.00)比3.00(3.00,3.00);Z=−3.21,P=0.001]方面图像质量更高。对于瘤体,3D SPACE序列的SNR优于2D TSE序列(119.95±39.83比83.94±40.34;t=−2.54,P=0.016);对于脂肪(213.56±95.26比191.22±59.47;t=0.80,P=0.430)及肌肉(41.86±19.34比40.40±15.58;t=0.24,P=0.820),2D TSE及3D SPACE序列的SNR差异无统计学意义;两序列对比噪声比差异无统计学意义(19.36±10.11比27.54±18.72;t=−1.54,P=0.140)。与术后病理结果对比,2D TSE序列的诊断一致性(Kappa=0.49,P=0.00)比3D SPACE序列低(Kappa=0.95,P=0.000),两序列对T分期的诊断准确度分别为76.00%和98.67%。结论2D TSE和3D SPACE序列显示直肠浆膜层或外膜、肠周脂肪、直肠系膜筋膜及瘤体一样可靠。3D SPACE序列对于显示直肠黏膜层及直肠肌层较2D TSE序列更优越。对于直肠癌的术前T分期,3D SPACE序列较传统高分辨2D TSE序列的诊断准确度更高,可更好地为临床制订治疗方案提供影像学依据。

基于衍生化3-氨基-2-恶唑烷酮的夹心酶联免疫分析

建立一种3-氨基-2-恶唑烷酮(3-amino-2-oxazolidinone,AOZ)夹心免疫检测方法。通过1,6-己二醇连接2-硝基-4-羧基苯甲醛和生物素合成针对AOZ的新型衍生试剂。在样品前处理时加入衍生试剂可对AOZ进行衍生,衍生产率为89%。在酶标板上包被抗AOZ单克隆抗体并以辣根过氧化物酶标记的亲和素或抗生物素抗体作为第二结合物可实现AOZ的夹心酶联免疫吸附检测(enzyme-linked immunosorbnent assay,ELISA)。从实际应用的角度,得到双抗夹心和抗体-亲和素夹心模式下两个表位的极限距离,分别为12Å和13Å,理想距离分别为16Å和17Å。在双抗夹心和抗体-亲和素夹心模式下的检出限分别达到1.8 pg/mL和0.8 pg/mL(以AOZ质量浓度计),相对于竞争ELISA,其灵敏度最高提高了25倍。平均回收率为73%~85%,平均相对标准偏差为9.0%。

高分辨率血管壁成像时3D SPACE T1压脂与非压脂序列对MCA狭窄病人图像信号、血管壁及斑块的影响

目的:探究高分辨率血管壁成像时利用可变翻转角实现最优化采集的3D快速自旋回波序列(3D-SPACE)T1压脂与非压脂序列对大脑中动脉(middle cerebral artery,MCA)狭窄病人图像信号、血管壁及斑块情况的影响。方法:选取2021年1月—2022年12月于滨州市中心医院接受颅内磁共振血管成像(MR angiography,MRA)检查并确诊的MCA狭窄患者72例为研究对象,患者均接受MCA MRI检查,然后再分别用3D SPACE T1压脂与非压脂序列测量,分析图像信号差异情况,对比不同序列测量的血管断面、管腔及斑块面积情况及图像质量主观评价;分析不同医师图像质量评分的一致性情况。结果:72例患者中,不同序列测量均可以清晰地将MCA斑块显示出来,但测量出的信号存在明显的差异。不同序列测量血管断面、管腔面积对比差异不显著(P>0.05);3D SPACE T1非压脂序列测量斑块面积大于压脂序列测量面积(P<0.05);2种序列管腔显示情况对比差异无统计学意义(P>0.05),其他图像质量对比差异有统计学意义(P<0.05)。2名医生图像质量评分具有良好的一致性。结论:高分辨率血管壁成像时3D SPACE T1非压脂序更有助于对MCA狭窄病人图像信号、血管壁及斑块的测量,可为临床提供治疗依据。

NUMERICAL MODELLING OF THREE-DIMENSION CHARACTERISTICS OF WIND-DRIVEN CURRENT IN THE BOHAI SEA

Three- dimension (3-D) wind-driven currents in the Bohai Sea in both winter and summer are calculated by using a 3- D barotropic steady model, and the results are consistent with observed flow char -acteristics. Based on the results, 3- D characteristics of flow, currents at different depths, compensated flow in the lower layer , long and narrow alongshore current, the area of upwelling and downwelling, main circulation in vertical profile, and the current in Bohai Strait are discussed.

Temporal Floorplanning Using Solution Space Smoothing Based on 3D-BSSG Structure

We develop a 3D bounded slice-surface grid （3D-BSSG） structure for representation and introduce the solution space smoothing technique to search for the optimal solution. Experiment results demonstrate that a 3D-BSSG structure based algorithm is very effective and efficient.

Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample (I center dot 4.6 mm x 5.6 mm) was scanned using high-resolution X-ray computed tomography (HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 mu m. Combined with three-dimensional (3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.