Monitoring Zenithal Total Delays over the three different climatic zones from IGS GPS final products:A comparison between the use of the VMF1 and GMF mapping functions

The International GNSS Service(IGS) final products(ephemeris and clocks-correction) have made the GNSS an indispensable low-cost tool for scientific research, for example sub-daily atmospheric water vapor monitoring. In this study, we investigate if there is a systematic difference coming from the choice between the Vienna Mapping Function 1(VMF1) and the Global Mapping Function(GMF) for the modeling of Zenith Total Delay(ZTD) estimates, as well as the Integrated Precipitable Water Vapor(IPWV) estimates that are deduced from them. As ZTD estimates cannot be fully separated from coordinate estimates, we also investigated the coordinate repeatability between subsequent measurements.For this purpose, we monitored twelve GNSS stations on a global scale, for each of the three climatic zones(polar, mid-latitudes and tropical), with four stations on each zone. We used an automated processing based on the Bernese GNSS Software Version 5.2 by applying the Precise Point Positioning(PPP)approach, L3 Ionosphere-free linear combination, 7 cutoff elevation angle and 2 h sampling. We noticed an excellent agreement with the ZTD estimates and coordinate repeatability for all the stations w.r.t to CODE(the Center for Orbit Determination in Europe) and USNO(US Naval Observatory) products, except for the Antarctic station(Davis) which shows systematic biases for the GMF related results. As a final step, we investigated the effect of using two mapping functions(VMF1 and GMF) to estimate the IPWV,w.r.t the IPWV estimates provided by the Integrated Global Radiosonde Archive(IGRA). The GPS-derived IPWV estimates are very close to the radiosonde-derived IPWV estimates, except for one station in the tropics(Tahiti).

M-Dixon quant和T2-mapping对杜氏肌营养不良症患儿进展前期及进展期运动功能的评估

目的探讨M-Dixon quant和T2-mapping技术评估杜氏肌营养不良症(DMD)患儿进展前期及进展期运动功能的价值,为精确评估DMD病情和监测随访提供合适的影像学工具。方法前瞻性收集40例经基因检测或组织病理活检确诊的DMD男性患儿,进展前期(<7岁)患儿20例,进展期(≥7岁)患儿20例。所有患儿均进行下肢M-Dixon quant和T2-mapping检查,观察进展前期及进展期患儿大腿肌肉的MRI表现,选取右侧大腿14块肌肉并测量其脂肪分数(FF)值和T2值。根据运动功能量表(MFM)评分对患儿进行运动功能评估并计算MFM总评分。采用Pearson相关分析2组患儿各肌肉FF值、T2值与MFM总评分的相关性(rFF,rT2)。结果进展前期DMD患儿大腿肌肉MRI表现为轻微脂肪浸润,随疾病进展表现为脂肪浸润程度加重。进展前期DMD患儿臀大肌、半膜肌、半腱肌FF值与MFM总评分均呈负相关(均P<0.05);除大收肌外,其余13块肌肉T2值与MFM总评分均呈负相关(均P<0.05),以股中间肌与MFM总评分的相关性最强。进展期DMD患儿14块肌肉FF值、T2值与MFM总评分均呈负相关(rFF为-0.877~-0.697,rT2为-0.968~-0.774,均P<0.05),以股外侧肌相关性最强。进展期DMD患儿每块肌肉的rT2均高于rFF。结论DMD患儿大腿肌肉受累有一定的进展规律。无论是进展前期还是进展期,相对于M-Dixon quant技术,T2-mapping技术能够更准确地反映疾病严重程度,疾病进展前期患儿的股中间肌和进展期患儿的股外侧肌T2值可作为评估DMD病情的良好指标。

RESEARCH ON THE CONSTRAINT MAPPING FROM FUNCTION TO ASSEMBLY

Assembly sketch is not only the visualization of abstract function, but alsothe template of detail design. Two kinds of information are needed to create assembly sketch:structure and assembly constraint. Most researches are aimed at bow to obtain Structures fromfunction, but the problem of how to obtain assembly constraint from function is ignored. Followingthe definition of assembly unit and the classification of function, a hierarchical mapping methodfrom function to assembly constraint is put forward, and the mapping method includes two steps. Thefirst step is the mapping from function to assembly semantics which is assembly expression andaccordant with engineer's design habit. The second one is the mapping from assembly semantics tobasic assembly constraints that are convenient for computer to handle. The mapping method is appliedto DDMS (design, drafting and management system) successfully.

Stability analysis of approximately multidimensional additive mappings on fuzzy spaces

The intention of this paper is to study new additive kind multi-dimensional functional equations inspired by several applications of difference equations in biology,control theory,economics,and computer science,as well as notable implementation of fuzzy ideas in certain situations involving ambiguity or vagueness.In the context of different fuzzy spaces,we demonstrate their various fundamental stabilities related to Ulam stability theory.An appropriate example is given to show how stability result fails when the singular case occurs.The findings of this study suggest that stability results are valid in situations with uncertain or imprecise data.The stability results obtained under these fuzzy spaces are compared with previous stability results.

TRANSFORMATION BETWEEN TWO KINDS OF EXPANSION COEFFICIENTS OF SYMMETRIC FUNCTIONS BASED ON MAPPING METHOD

This paper discusses the definitions and properties of two kinds of fundamental symmetric functions, which are based on AND-OR-NOT algebraic system and AND-Exclusive OR algebraic system, respectively. Based upon it, some mapping transformation methods between two kinds of expansion coefficients of an arbitrary symmetric, function in the complete set of two fundamental symmetric functions.

T1 mapping联合胆道-椎旁肌信号强度比预测肝功能的价值

目的探讨钆塞酸二钠增强MRI T1 mapping联合胆道-椎旁肌信号强度比评估肝功能的价值。资料与方法前瞻性收集北京友谊医院2020年8月—2022年2月72例行钆塞酸二钠增强MRI的患者,将患者按照肝功能Child-Pugh分级分为肝功能正常组22例、A级组35例、B+C级组15例。患者均于增强前及增强后20 min扫描T1 mapping序列,测量肝实质的增强前及增强后(T1post)T1弛豫时间,并计算肝脏T1弛豫时间减少率(ΔT1)。在肝胆期图像上测量胆道信号及椎旁肌信号,计算胆道-椎旁肌信号强度比(SIR)。评价医师间测量结果的一致性,观察各指标与肝功能分级的相关性,比较不同组间各指标的差异和诊断效能。结果T1post与肝功能分级呈正相关(r=0.683,P<0.001),随肝功能受损程度加重逐渐增加。ΔT1、SIR、SIR×ΔT1与肝功能分级呈负相关(r=-0.764、-0.729、-0.826,P均<0.001),随肝功能受损程度加重逐渐减小。T1post、ΔT1、SIR、SIR×ΔT1在各肝功能分级组间差异均有统计学意义(F=27.491、55.782、48.410、46.809,P均<0.05);两两比较中,各指标差异均有统计学意义(P<0.05)。各指标中的诊断效能最优者为SIR×ΔT1,其鉴别肝功能正常组与肝硬化组、A级组与B+C级组的曲线下面积分别为0.915、0.984。结论T1post、ΔT1、SIR、SIR×ΔT1与肝功能Child-Pugh分级均有较强的相关性。SIR×ΔT1在各组间鉴别能力更好,可作为定量评估肝功能的影像指标。

A Two-step Estimation Method of Troposphere Delay with Consideration of Mapping Function Errors

Mapping function errors are usually not taken into consideration, when space geodetic data observed by VLBI, GNSS and some other techniques are utilized to estimate troposphere delay, which could, however, probably bring non-ignorable errors to solutions. After analyzing the variation of mapping function errors with elevation angles based on several-year meteorological data, this paper constructed a model of this error and then proposed a two-step estimation method of troposphere delay with consideration of mapping function errors. The experimental results indicate that the method put forward by this paper could reduce the slant path delay residuals efficiently and improve the estimation accuracy of wet tropospheric delay to some extent.

Manufacturing Oriented Fuzzy Function-Feature Mapping

The mechanism of the Concurrent Engineering(CE)and the methods of the manufacturing consultation are discussed. CE-oriented computer aided manufacture consulting methods are one of the key issues in concurrent design. The problems are settled in part function-feature mapping in concurrent design. The fuzzy set theory is applied to the function-feature mapping. A method for part function-feature mapping based on fuzzy theory is presented.

Experimental Evaluation of Objective Functions for Well-balanced Mapping

High performance of parallel computing on a message-passing multicomputer System relies on the balance of the workloads located on the processing elements of the System and the minimum communication ovcrheads among them. Mapping is the technology to partition the problem domain wellbalanced into multiple distinct execution tasks based on some measures. In mapping, a good objective function is the criterion to guarantce the distinct execution tasks equitable. In this paper, we evaluate five categories of those existed objective functions with three different problem subjects using experiments and find an objective function is much suitable for all kinds of problems.

SOME NEW ITERATED FUNCTION SYSTEMS CONSISTING OF GENERALIZED CONTRACTIVE MAPPINGS

Iterated function systems （IFS） were introduced by Hutchinson in 1981 as a natural generalization of the well-known Banach contraction principle. In 2010, D. R. Sahu and A. Chakraborty introduced K-Iterated Function System using Kannan mapping which would cover a larger range of mappings. In this paper, following Hutchinson, D. R. Sahu and A. Chakraborty, we present some new iterated function systems by using the so-called generalized contractive mappings, which will also cover a large range of mappings. Our purpose is to prove the existence and uniqueness of attractors for such class of iterated function systems by virtue of a Banach-like fixed point theorem concerning generalized contractive mappings.

Preoperative functional MRI localization of language areas in Chinese patients with brain tumors Validation with intraoperative electrocortical mapping

Ten Chinese patients with brain tumors involving language regions were selected. Preoperative functional MRI was performed to locate Broca＇s or Wernicke＇s area, and the cortex that was essential for language function was determined by electrocortical mapping. A site-by-site comparison between functional MRI and electrocortical mapping was performed with the aid of a neuronavigation device. Results showed that the sensitivity and specificity of preoperative functional MRI were 80.0% and 85.0% in Broca＇s area and 66.6% and 85.2% in Wemicke＇s area, respectively. These experimental findings indicate that functional MRI is an accurate, reliable technique with which to identify the location of Wernicke＇s area or Broca＇s area in patients with brain tumors.

Feature Mapping and Recuperation by Using Elliptical Basis Function Networks for Robust Speaker Verification

The performance of speaker verification systems is often compromised under real world environments. For example, variations in handset characteristics could cause severe performance degradation. This paper presents a novel method to overcome this problem by using a non linear handset mapper. Under this method, a mapper is constructed by training an elliptical basis function network using distorted speech features as inputs and the corresponding clean features as the desired outputs. During feature recuperation, clean features are recovered by feeding the distorted features to the feature mapper. The recovered features are then presented to a speaker model as if they were derived from clean speech. Experimental evaluations based on 258 speakers of the TIMIT and NTIMIT corpuses suggest that the feature mappers improve the verification performance remarkably.

FUZZY APPROACHING SET AND FUZZYAPPROACHING FUNCTIONAL MAPPING

By establishing the concepts of fuzzy approaching set and fuzzy approaching functional mapping and making research on them, a new method for time series prediction is introduced.

初探T1 mapping和APTw成像对慢性肾病的诊断价值

目的初探纵向弛豫时间定量成像(T1 mapping)和酰胺质子转移加权(amide proton transfer weighted,APTw)成像鉴别慢性肾病(chronic kidney disease,CKD)患者与健康人群的价值。材料与方法回顾性分析2019年8月至2020年10月行3.0 T MRI检查的CKD患者病例资料共21例(女6例,男15例),所有患者均经大连医科大学附属第一医院肾内科医师依据CKD临床实践指南确诊;同时收集24例健康志愿者临床资料作为对照组。将所有原始图像导入ISP工作站,生成伪彩图。由两名影像科诊断医师采用双盲法分别从肾的上极、中部、下极各选择一个层面并于皮质和髓质中分别放置感兴趣区(region of interest,ROI),面积约10~20 mm^(2),避开肾窦、大血管及肾周组织。测量所得皮髓质T1值与APT值应用SPSS 26.0软件进行统计学分析:应用组内相关系数(intra-class correlation coefficients,ICC)进行观察者间测量结果一致性检验;根据数据正态分布情况,采用独立样本t检验或Mann-Whitney U检验分析两组间参数值差异,P<0.05为差异具有统计学意义;采用受试者工作特征(receiver operating characteristic,ROC)曲线分析各参数诊断效能,根据最大约登指数得到相对应的阈值、敏感度和特异度,并计算曲线下面积(area under the curve,AUC)值。结果两位观察者间测量结果一致性良好(ICC>0.75)。CKD组双肾皮质T1值和皮质APT值显著高于健康对照组(P<0.05);左肾皮质T1值鉴别CKD的AUC值为0.887,敏感度66.7%,特异度100.0%;左肾皮质APT值鉴别CKD的AUC值为0.966,敏感度95.2%,特异度95.8%;右肾皮质T1值鉴别CKD的AUC值为0.960,敏感度76.2%,特异度100.0%;右肾皮质APT值鉴别CKD的AUC值为0.921,敏感度85.7%,特异度91.7%。结论T1 mapping与APTw成像可无创有效鉴别CKD,基于二者的定量参数在一定程度上反映了单侧肾脏各自结构与功能的改变,有望为临床疾病诊断提供一定的参考价值。

磁共振T_(1)-mapping特征参数评价扩张型心肌病心肌纤维化及与射血分数的相关性

目的探讨心血管磁共振(CMR)T_(1)-mapping技术评价扩张型心肌病(DCM)心肌纤维化的价值,分析T_(1)-mapping量化指标与射血分数(EF)的相关性。方法选择2015年至2017年在郑州大学第一附属医院治疗的48例DCM患者(DCM组),其中男性38例,女性10例;年龄24~73岁,平均年龄47.40岁;身高155~178 cm,平均身高169 cm;体质量49~98 kg,平均体质量75.51 kg。同期选择24例健康志愿者作为对照组,其中男性14例,女性10例;年龄28~71岁,平均年龄47.67岁;身高155~179 cm,平均身高167 cm;体质量55~85 kg,平均体质量69.21 kg。全部受试者行3.0 T CMR检查。通过心脏短轴电影图像计算EF。采用改进的Look-Locker反转恢复(MOLLI)序列获取T_(1)-mapping图像。用MATLAB软件提取T_(1)-mapping图像直方图参数,包括5组百分位数(P10、P25、P50、P75、P90)、最小值、最大值、偏度系数(Skewness)、峰度系数(Kurtosis)、标准差(s)、均值等。比较T_(1)-mapping参数与EF的相关性。DCM组根据延时钆增强(LGE)图像是否有强化,将DCM组分为LGE(+)亚组和LGE(-)亚组。结果DCM组EF与对照组比较,差异有显著统计学意义[(21.75±9.31)%vs(55.22±7.39)%。P<0.01]。DCM组分为LGE(+)亚组33例和LGE(-)亚组15例。DCM组均值、s、最大值及P10、P25、P50、P75、P90等T_(1)-mapping直方图参数较对照组显著上升,而EF较对照组显著降低(P<0.01)。均值、s、最大值、P10、P25、P50、P75、P90等T_(1)-mapping参数与EF呈负相关(r=-0.546、-0.380、-0.580、-0.387、-0.502、-0.564、-0.583、-0.562,P<0.05)。结论T_(1)-mapping技术有助于诊断DCM心肌纤维化,尤其是弥漫性心肌纤维化,T_(1)-mapping参数与EF呈负相关。

基于T1 mapping序列的定量参数鉴别肺癌病理类型的应用研究

目的评估基于纵向弛豫时间定量序列(T1 mapping)的定量参数预测肺癌病理类型的可行性。材料与方法共收治经病理确诊的肺癌患者117例,包括腺癌62例,鳞状细胞癌26例,小细胞肺癌(small cell lung cancer,SCLC)29例,于治疗前行常规MRI、T1 mapping检查。采用B1场校正的3D可变翻转角VIBE序列分别于增强前及增强后5 min采集T1 mapping图像,测量肿瘤大小、增强前T1值(T1pre)、增强后T1值(T1post),并计算增强前后T1值变化△T1、增强前后T1值变化率△T1%。采用SPSS和MedCalc软件进行分析,运用logistic回归联合ROC曲线下面积(area under the curve,AUC)评价各组各定量参数的差异及多参数联合的诊断价值。结果腺癌、鳞状细胞癌和SCLC的ΔT1、ΔT1%和T1post差异有统计学意义(P<0.05),而T1pre差异无统计学意义(P=0.506)。鉴别SCLC和非小细胞肺癌(non-small cell lung cancer,NSCLC)的T1post、△T1和△T1%值的AUC分别为0.856、0.805和0.864,3个参数的组合可以提高鉴别SCLC和NSCLC的诊断准确度(AUC=0.870,P<0.05)。△T1、△T1%鉴别腺癌和鳞状细胞癌的AUC分别为0.755和0.767,两者联合可提高诊断准确度(AUC=0.771,P>0.05)。T1post、△T1%鉴别鳞状细胞癌和SCLC的AUC分别为0.788和0.818,两者联合可提高诊断准确度(AUC=0.831,P>0.05)。T1post、△T1%鉴别腺癌和SCLC的AUC分别为0.895、0.873,二者联合可提高诊断准确度(AUC=0.898,P>0.05)。结论T1 mapping可以无创定量地获得腺癌、鳞状细胞癌和SCLC的T1值,可用于区分SCLC与NSCLC以及鳞状细胞癌和腺癌,具有一定的临床应用价值。

T_(2)-mapping定量评估脊髓性肌萎缩症严重程度

目的:探讨磁共振T_(2)-mapping技术定量评估儿童脊髓性肌萎缩症(SMA)严重程度的临床价值。方法:前瞻性将28例在本院经基因检测确诊的SMA患儿纳入本研究。记录每例患儿的年龄、体质指数(BMI)和汉默史密斯功能运动量表扩展版(HFMSE)评分。所有患儿行大腿常规序列MRI和T_(2)-mapping扫描,测量右侧骨盆和大腿部位的13块肌肉(右侧臀大肌、阔筋膜张肌、股直肌、股内侧肌、股外侧肌、股中间肌、缝匠肌、半膜肌、半腱肌、股二头肌长头肌、大收肌、长收肌和股薄肌)的T_(2)值,并得到彩色编码的肌肉组织T_(2)值分布图,以确定受累最严重的肌肉。采用两独立样本t检验比较Ⅱ和Ⅲ型SMA患者13块肌肉的T_(2)值、平均T_(2)值、HFMSE评分、年龄及BMI的组间差异,并采用Spearman秩相关分析评估肌肉T_(2)值与各项临床指标的相关性。结果:13块肌肉中,臀大肌的平均T_(2)值最高[(63.3±11.9)ms],长收肌的平均T_(2)值最低[(42.5±4.5)ms],长收肌的平均T_(2)值明显低于其它肌肉(P均<0.05)。彩色编码的T_(2)值分布图提供了对肌肉T_(2)值异质性分布的有效视觉评估。Ⅱ型SAM患者的阔筋膜张肌T_(2)值明显高于Ⅲ型(P<0.01),年龄及HFMSE评分均明显低于Ⅲ型(P<0.01)。在Ⅱ型、Ⅲ型及所有SMA患者中,肌肉平均T_(2)值均与HFMSE呈高度负相关(r=-0.696、-0.724、-0.657,P均<0.01)。13块肌肉中,阔筋膜张肌的T_(2)值与HFMSE评分的相关性最高(r=-0.743,P<0.001)。结论:磁共振T_(2)-mapping技术能客观定量评估SMA患儿疾病的严重程度,有助于识别该疾病的肌肉受累模式。阔筋膜张肌的T_(2)值可较准确地鉴别Ⅱ型与Ⅲ型SMA患者,此条肌肉可能是评估SMA疾病严重程度的最理想的目标肌肉。

Recent progress and future prospect of digital soil mapping： A review

To deal with the global and regional issues including food security, climate change, land degradation, biodiversity loss, water resource management, and ecosystem health, detailed accurate spatial soil information is urgently needed. This drives the worldwide development of digital soil mapping. In recent years, significant progresses have been made in different aspects of digital soil mapping. The main purpose of this paper is to provide a review for the major progresses of digital soil mapping in the last decade. First, we briefly described the rise of digital soil mapping and outlined important milestones and their influence, and main paradigms in digital soil mapping. Then, we reviewed the progresses in legacy soil data, environmental covariates, soil sampling, predictive models and the applications of digital soil mapping products. Finally, we summarized the main trends and future prospect as revealed by studies up to now. We concluded that although the digital soil mapping is now moving towards mature to meet various demands of soil information, challenges including new theories, methodologies and applications of digital soil mapping, especially for highly heterogeneous and human-affected environments, still exist and need to be addressed in the future.

核磁T2 mapping技术定量评估2型糖尿病患者左心室心肌功能的临床应用价值

目的观察核磁T2 mapping技术观察2型糖尿病患者心肌横向弛豫时间(T2值)的改变情况,了解核磁T2 mapping技术定量评估左室心肌功能的价值。方法收集2015年6月至2017年6月经该院诊断的2型糖尿病患者57例作为糖尿病组,并随机选取无糖尿病或相关性疾病的57例患者作为对照组。所有患者均进行心脏磁共振(CMR)检查,将所有患者的原始CMR数据传至后处理工作站,T2 mapping分别选择FUNCTOOL软件进行后处理,增加伪彩色。短轴位观察左室前壁、侧壁、下壁、前间隔和后间隔情况,四腔心观察侧壁和后间隔情况,两腔心观察后壁和前间隔情况,分别测量左室前壁、后壁、侧壁、下壁、前间隔和后间隔感兴趣区的T2值,对比分析糖尿病组与对照组的T2值。结果两组所有患者的每例样本均包括6层短轴位、1层两腔心和1层四腔心,每组共342层短轴位图像、57层两腔心图像和57层四腔心图像。糖尿病组短轴位、两腔心和四腔心的Ⅲ、Ⅳ级图像分别为83.9%(287/342)、78.9%(45/57)和80.7%(46/57),其CMR图像质量效果佳,与对照组的CMR图像质量差异无统计学意义(P>0.05)。糖尿病组的各肌壁T2值大于对照组肌壁的T2值,差异有统计学意义(P<0.05)。结论核磁T2 mapping技术可用于观察糖尿病患者的心肌改变情况,通过定量评估心肌T2值可有效评估左室心肌功能,具有重要临床应用价值。

ELXED POINT THEOREM OF COMPOSITION g-CONTRACTION MAPPING AND ITS APPLICATIONS

Any composition sequential mapping, periodic composition mapping of a complete non-empty metric space M into M with geometric mean contraction ratio less than 1 ( simplifying as 'g-contraction mapping' ) has a unique fixed point in M . Applications of the theorem to the proof of existence and uniqueness of the solutions of a set of non-linear differential equations and a coupled integral equations of symmetric bending of shallow shell of revolution are given.