Changes in three-dimensional power Doppler ultrasound features before and after neoadjuvant chemotherapy for cervical cancer and their relationship with malignant molecule expression

Objective:To study the changes in three-dimensional power Doppler ultrasound features before and after neoadjuvant chemotherapy for cervical cancer and their relationship with malignant molecule expression.Methods: The patients who were diagnosed with cervical cancer and received neoadjuvant chemotherapy in Wuhan Red Cross Hospital between March 2015 and October 2017 were selected as the cervical cancer group, and the patients who received cervical biopsy and were diagnosed with stage I cervical intraepithelial neoplasia by pathological findings during the same period were selected as the control group. Before biopsy, three-dimensional power Doppler ultrasonography was performed to measure VI, FI and VFI;the tissues of cervical cancer group before and after chemotherapy as well as the biopsy tissues of control group were collected to measure the expression of proliferation genes, invasion genes and angiogenesis genes.Results: The VI, FI and VFI levels as well as the Piwil2 gene (Piwil2), CyclinD1, N-Myc downstream regulated gene 3 (NDRG3), CXC chemokine ligand 5 (CXCL5), cathepsin-L (CAT-L), EGF-containing fibulin-like extracellular matrix protein 1 (EFEMP1), angiotensin (Ang)1, Ang2 and angiopoietin-like protein 4 (ANGPTL4) mRNA expression levels in the tissues of cervical cancer group before and after chemotherapy were all significantly higher than those of control group whereas the thrombospondin 2 (THBS2), Smac gene (Smac), large tumor suppressor kinase 1 (LATS1), reversion-inducing-cysteine-rich protein with kazal motifs (RECK) and plas minogen activator inhibitor 1 (PAI-1) mRNA expression levels in the tissues were all significantly lower than those of control group, and the VI, FI and VFI levels as well as the Piwil2, CyclinD1, NDRG3, CXCL5, CAT-L, EFEMP1, Ang1, Ang2 and ANGPTL4 mRNA expression levels in the tissues of cervical cancer group after chemotherapy were all significantly lower than those before chemotherapy whereas the THBS2, Smac, LATS1, RECK and PAI-1 mRNA expression levels were all significantly higher than those before chemotherapy;the VI, FI and VFI levels in cervical cancer tissues were positively correlated with the Piwil2, CyclinD1, NDRG3, CXCL5, CAT-L, EFEMP1, Ang1, Ang2 and ANGPTL4 mRNA expression levels, and negatively correlated with the THBS2, Smac, LATS1, RECK and PAI-1 mRNA expression levels.Conclusion: The changes in the three-dimensional power Doppler ultrasound parameters before and after neoadjuvant chemotherapy for cervical cancer can reflect the changes in proliferation, invasion and angiogenesis gene expression in the lesions.

Antidiastole Value of Three-dimensional Ultrasonography and Power Doppler between Uterine Parenchyma Lumps and Endometrial Cancer:A Retrospective Study

Sometimes endometrial polyps,submucosal myomas,and endometrial cancer show similar findings under ultrasonography.The aim of this study was to assess the antidiastole value of blood flow parameters using three-dimensional(3D)power Doppler ultrasonography angiography(PDA)between endometrial cancer and uterine parenchyma lumps.The data of the blood flow indices in 3D-PDA including the vascularization index(VI),flow index(FI),and vascularization flow index(VFI)in 40 patients with endometrial cancer and 41 patients with uterine parenchyma lumps(endometrial polyps and submucosal myomas)were retrospectively analysed and compared utilizing Virtual Organ Computer-aided AnaLysis(VOCAL)software.The results showed that all the blood flow parameters(VI,FI,VFI)were significantly higher in women with endometrial cancer than in those with uterine parenchyma lumps(P<0.001).The area under the curve of ROC of VI,FI,and VFI was 0.98,0.84,and 0.97,respectively.Thus,the best predictor of endometrial carcinoma was VI with a sensitivity of 97.0% and a specificity of 91.0%.The optimal cutoff value of VI was 4.06%.Our data demonstrated that all of the blood flow signal parameters(including VI,FI,and VFI)in 3D power Doppler ultrasonography had significant antidiastole values between endometrial cancer and uterine parenchyma lumps to assist clinicians in properly diagnosing patients.

Real-time Three-Dimensional Color Doppler Flow Imaging： An Improved Technique for Quantitative Analysis of Aortic Regurgitation

The recently introduced real-time three-dimensional color Doppler flow imaging （RT-3D CDFI） technique provides a quick and accurate calculation of regurgitant jet volume （RJV） and fraction. In order to evaluate RT-3D CDFI in the noninvasive assessment of aortic RJV and regurgitant jet fraction （RJF） in patients with isolated aortic regurgitation, real-time three-dimensional echocardiographic studies were performed on 23 patients with isolated aortic regurgitation to obtain LV end-diastolic volumes （LVEDV）, end-systolic volumes （LVESV） and RJV, and then RJF could be calculated. The regurgitant volume （RV） and regurgitant fraction （RF） calculated by two-dimensional pulsed Doppler （2D-PD） method served as reference values. The results showed that aortic RJV measured by the RT-3D CDFI method showed a good correlation with the 2D-PD measurements （r= 0.93, Y=0.89X＋ 3.9, SEE= 8.6 mL, P〈0.001 ）; the mean （SD） difference between the two methods was - 1.5 （9.8） mL. % RJF estimated by the RT-3D CDFI method was also correlated well with the values obtained by the 2D-PD method （r=0.88, Y=0.71X＋ 14.8, SEE= 6.4 %, P〈0. 001）; the mean （SD） difference between the two methods was -1.2 （7.9） %. It was suggested that the newly developed RT-3D CDFI technique was feasible in the majority of patients. In patients with eccentric aortic regurgitation, this new modality provides additional information to that obtained from the two-dimensional examination, which overcomes the inherent limitations of two-dimensional echocardiography by depicting the full extent of the jet trajectory. In addition, the RT-3D CDFI method is quick and accurate in calculating RJV and RJF.

Optimization of three-dimensional boiling enhancement structure at evaporation surface for high power light emitting diode

A theoretical model of phase change heat sink was established in terms of thermal resistance network. The influence of different parameters on the thermal resistance was analyzed and the crucial impact factors were determined. Subsequently, the forming methods including ploughing-extrusion and stamping method of boiling enhancement structure at evaporation surface were investigated, upon which three-dimensional microgroove structure was fabricated to improve the efficiency of evaporation. Moreover, the crucial parameters related to the fabrication of miniaturized phase change heat sink were optimized. The heat transfer performance of the heat sink was tested. Results show that the developed phase change heat sink has excellent heat transfer performance and is suitable for high power LED applications.

Ultrafast power Doppler imaging for ischemic encephalopathy:A case report

BACKGROUND Severely elevated intracranial pressure due to various reasons,such as decreased cerebral perfusion,can lead to devastating neurological outcomes,such as brain herniation.Decompression craniectomy is a life-saving procedure that is commonly performed for such a critical situation,but the changes in cerebral microvessels after brain herniation and decompression are unclear.Ultrafast power Doppler imaging(uPDI)is a new microvascular imaging technology that utilizes high frame rate plane/diverging wave transmission and advanced clutter filters.uPDI significantly improves Doppler sensitivity and can detect microvessels,which are usually invisible using traditional ultrasound Doppler imaging.CASE SUMMARY In this report,uPDI was used for the first time to observe the brain blood flow of a hypoperfusion area in a 4-year-old girl who underwent decompression craniectomy due to refractory intracranial hypertension(ICP)after malignant brain tumor surgery.B-mode imaging was used to verify the increased densities of the cerebral cortex and basal ganglia that were observed by computed tomography.CONCLUSION uPDI showed the local blood supplies and anatomical structures of the patient after decompressive craniectomy.uPDI is potentially a more intuitive and noninvasive method for evaluating the effects of severe ICP on cerebral microvessels.

Roughness evaluation of three-dimensional asphalt pavement based on two-dimensional power spectral density

To solve the problem of the lack of comprehensive evaluation of three-dimensional(3D)asphalt pavement roughness,a method for evaluating the asphalt pavement roughness is proposed based on two-dimensional(2D)power spectral density(PSD).By calculating the 2D PSD of a 3D asphalt pavement and converting it into the longitudinal average asphalt pavement PSD,the relationship between the evaluation method of the 3D asphalt pavement roughness and the current evaluation standard of roughness is established.Combined with the road-fitting formula used in international standards,the elevation data of the A,B,C,and D grades of the 3D asphalt pavement are simulated by the harmonic superposition method.According to the proposed method,the longitudinal PSD of each level of simulated asphalt pavement is calculated and compared with the standard spectral line of each pavement level.This approach verifies the effectiveness of the proposed method in evaluating the roughness of the 3D asphalt pavement.Compared with the PSD of a certain horizontal profile elevation,it is verified that the fluctuation amplitude of the spectral line calculated by the proposed method is greatly improved.The results show that the proposed method can evaluate the roughness of asphalt pavements more comprehensively and accurately and has strong practicability.

Power Doppler ultrasonographic assessment of the ankle in patients with inflammatory rheumatic diseases

Ankle involvement is frequent in patients with inflammatory rheumatic diseases, but accurate evaluation by physical examination is often difficult because of the complex anatomical structures of the ankle. Over the last decade, ultrasound(US) has become a practical imaging tool for the assessment of articular and periarticular pathologies, including joint synovitis, tenosynovitis, and enthesitis in rheumatic diseases. Progress in power Doppler(PD) technology has enabled evaluation of the strength of ongoing inflammation. PDUS is very useful for identifying the location and kind of pathologies in rheumatic ankles as well as for distinguishing between inflammatory processes and degenerative changes or between active inflammation and residual damage. The aim of this paper is to illustrate the US assessment of ankle lesions in patients with inflammatory rheumatic diseases, including rheumatoid arthritis, spondyloarthritis, and systemic lupus erythematosus, focusing on the utility of PDUS.

High-precision three-dimensional atom localization via probe absorption at room temperature

A scheme is used to explore the behavior of three-dimensional(3D)atom localization in a Y-type hot atomic system.We can obtain the position information of the atom due to the position-dependent atom–field interaction.We study the influences of the system parameters and the temperature on the atom localization.More interestingly,the atom can be localized in a subspace when the temperature is equal to 323 K.Moreover,a method is proposed to tune multiparameter for localizing the atom in a subspace.The result is helpful to achieve atom nanolithography,photonic crystal and measure the center-of-mass wave function of moving atoms.

Correlation between Perifollicular Vascularity and Outcome in Stimulated Intrauterine Insemination Treatment Cycles: A Study Using Two-Dimensional Transvaginal Power Doppler Ultrasound

Objective:?The aim of this study is to assess any potential relationship between perifollicular vascularity and occurrence of pregnancy in cases of stimulated IUI cycles using the subjective grading system by 2D transvaginal power Doppler ultrasonography.?Design: A prospective cross sectional cohort study. Method: This is a prospective cross-sectional cohort study of 90 stimulated IUI treatment cycles. Selected women were prescribed clomiphene citrate combined with highly purified urinary follicle stimulating hormone. All patients underwent serial transvaginal ultrasound scans starting from day 6 to 7 of the cycle. Perifollicular Doppler blood flows were assessed in dominant follicles ≥18 mm. The patients then were categorized into 3 groups (high vascularity group {G3 & G4}, low vascularity group {G1 & G2} and mixed grades group). Other parameters measured included number of follicles ≥ 18 mm in both ovaries, endometrial thickness and estradiol (E2) level . Human chorionic gonadotropin (hCG) injection 10,000 IU IM was given to the patient when the dominant follicle reached 18 mm in diameter. At that time, the endometrium was evaluated as regards endometrial thickness. IUI was carried out using prepared/“washed” semen (husband). All patients received luteal support in the form of progesterone from day of IUI for 14 days. Serum Β-hCG was estimated 2 weeks after insemination. Results: In this study, from all 90 cases only 8 cases got pregnant with pregnancy rate of 8.88% (6 cases got pregnant in high grade vascularity group;2 cases in mixed grades group and no cases got pregnant?in low grade group). There was statistically significant difference among the 3 groups as regarding?the pregnancy rate (P value = 0.02). There is statistically significant difference in perifollicular resistance index (RI) and pulsatility index (PI) between pregnant and non pregnant cases (P value = 0.016 and 0.047 respectively). In this study, there is no statistically significant difference between pregnant and non pregnant cases as regarding endometrial thickness and E2 level at the day of hCG administration (P value = 0.39 and 0.76 respectively). Conclusion: Perifollicular blood-flow assessment by 2D transvaginal power Doppler is a good predictive for the outcome of stimulated IUI cycles.

Preoperative serum vascular endothelial growth factor correlated to three dimensional power Doppler indices in ovarian masses

Objective: To assess the preoperative serum levels of vascular endothelial growth factor (VEGF) in ovarian masses compared to normal controls and to find a correlation between VEGF and Doppler indices in ovarian masses. Methods: The study was conducted from December 2009 to September 2012 in the oncology and ultrasound units in department of obstetrics and gynecology, Ain Shams University on 150 patients with ovarian masses. During preoperative workup, serum Ca-125 levels and serum VEGF levels were obtained. Ultrasonographic examination included two and three dimensional power Doppler ultrasound (3DPD). Laparotomic approaches were undertaken to obtain the final pathologic results. VEGF was measured in one hundred normal cases as controls. Results: Final ovarian pathology revealed seventy three malignant ovarian masses and seventy seven were benign. Serum Ca-125 levels in malignant cases were higher compared to those in benign cases (p < 0.001). Preoperative serum VEGF revealed higher levels in malignant ovarian masses than benign conditions and normal controls (p < 0.001). Three dimensional power Doppler indices, vascularization index (VI), flow index (FI) and vascularization flow index (VFI), correlated positively with serum VEGF levels. Conclusion: Preoperative serum VEGF revealed higher levels in malignant ovarian masses than benign conditions and normal controls. These levels positively correlated with the Doppler vascular indices of the masses.

Three-Dimensional Velocity Distribution Measurement Using Ultrasonic Velocity Profiler with Developed Transducer

This study describes an ultrasonic velocity profiler that uses a new ultrasonic array transducer with unique 5-element configuration, with all five elements acting as transmitters and four elements as receivers. The receivers are designed to reduce the amount of uncertainty. As the fluid moves through this setup, four Doppler frequencies are obtained. The multi-dimensional velocity information along the measurement line can be reconstructed. The transducer has a compact geometry suitable for a wide range of applications, including narrow flow areas. The transducer’s basic frequency and sound pressure are selected and evaluated to be compatible with the application. First, to confirm the measurement ability, the measurement of the developed system in two-dimensional flow is validated by comparing it to the theoretical data. The uncertainty of measurement was within 15%. Second, the three-dimensional measurement in turbulent and swirling flow is proved experimentally to check the applicability of the proposed technique.

Comparative Study of Radiological Changes in Hands and Feet in Patients Suffering from Early Rheumatoid Arthritis by Power Doppler Ultrasound and Direct Digital Radiography

Rheumatoid arthritis is a chronic multisystem disease of unknown cause. The characteristic feature of RA is persistent inflammatory synovitis. The natural history of disease is such that the early months of the disease are critical period during which reversible joint damage occurs. So early diagnosis of RA and appropriate drug application is the only way to save a patient from this crippling disease. In India, the cost of investigations is a significant factor for most of the patients. Ultrasonography or Power Doppler Ultra Sound (PDUS) has the advantage of being economic in spite of its sensitivity in assessing both inflammatory and destructive changes. The aim of the present study was to evaluate the diagnostic efficiency of PDUS in early rheumatoid arthritis. The study was performed with the patients attending Rheumatology Clinic. A total number of 106 patients of clinically suspected rheumatoid arthritis were studied as per selection criteria. Radiological examinations of hands were done by digital radiography and PDUS in a group of 53 patients, assessment of foot changes by PDUS and Digital Radiography were done in another similar group of 53 patients. Final diagnosis by ACR EULAR-2010 criteria is done for all the patients. The comparative study reveals that synovial vascularity as demonstrated by PDUS is much more effective in diagnosing early rheumatoid arthritis, both in hand and in feet than digital radiograph. PDUS of feet may yield earlier and better findings than hands, which is conventionally used in patients suffering from early rheumatoid arthritis.

三维能量多普勒超声预测宫颈癌化疗效果的临床价值

目的探讨三维能量多普勒超声(3D-PDU)预测宫颈癌化疗效果的临床应用价值。方法选取在我院接受新辅助化疗治疗的宫颈癌患者160例,根据化疗效果分为有效组103例和无效组57例,比较两组3D-PDU血流参数[血管形成-血流指数(VFI)、血流指数(FI)及血管形成指数(VI)]的差异。采用多因素Logistic回归分析筛选预测宫颈癌患者化疗效果的独立危险因素,并建立宫颈癌患者化疗效果风险预测模型;采用Hosmer-Lemeshow检验评估模型的拟合度;绘制受试者工作特征(ROC)曲线分析模型的预测效能。结果化疗后,两组VFI、FI及VI均较化疗前下降,且有效组上述参数均低于无效组,差异均有统计学意义(均P<0.05)。多因素Logistic回归分析显示,化疗后VFI、FI及VI均为预测宫颈癌患者化疗效果的独立危险因素(OR=2.826、4.637、3.216,均P<0.05),建立宫颈癌患者化疗效果风险预测模型为:Logit(P)=1/[1+e^((-4.609+1.039×化疗后VFI+1.534×化疗后FI+1.168×化疗后VI))]。Hosmer-Lemeshow检验显示模型的拟合度较好(χ^(2)=4.635,P=0.781);ROC曲线分析显示模型预测宫颈癌患者化疗效果的曲线下面积为0.882(P<0.05)。结论应用3D-PDU可以较好地预测宫颈癌化疗效果,具有一定的临床应用价值。

经阴道三维能量多普勒超声联合二维剪切波弹性成像预测备孕女性妊娠结局的临床价值

目的应用经阴道三维能量多普勒超声(3D-PDI)联合二维剪切波弹性成像(2D-SWE)评估备孕女性子宫内膜容受性,探讨其预测妊娠结局的临床应用价值。方法选取在我院接受卵泡检测的87例备孕女性,均于排卵第7~8天(种植窗期)行经阴道3D-PDI检查,于增殖期行2D-SWE检查,然后随访6周,根据妊娠结局将其分为受孕组31例和未受孕组56例。比较两组子宫内膜厚度、容积、回声类型、血流分型、子宫螺旋动脉搏动指数(PI)、阻力指数(RI)、收缩期峰值流速与舒张末期流速比值(S/D)、血管化指数(VI)、血流指数(FI)、血管化血流指数(VFI),以及子宫内膜杨氏模量平均值(以下简称杨氏模量值)的差异。绘制受试者工作特征(ROC)曲线分析经阴道3D-PDI和2D-SWE参数单独及联合应用对备孕女性妊娠结局的预测价值。结果受孕组子宫内膜厚度和FI均高于未受孕组,S/D和子宫内膜杨氏模量值均低于未受孕组,差异均有统计学意义(均P<0.05);两组子宫内膜容积、回声类型、血流分型及PI、RI、VI、VFI比较差异均无统计学意义。ROC曲线分析显示,子宫内膜厚度、FI、S/D和子宫内膜杨氏模量值预测备孕女性妊娠结局的曲线下面积分别为0.789、0.851、0.853和0.840,联合应用的曲线下面积为0.895,高于各参数单独应用,差异均有统计学意义(均P<0.05)。结论经阴道3D-PDI联合2D-SWE可准确评估备孕女性子宫内膜容受性,对预测其妊娠结局有较好的临床应用价值。

超声评分法联合三维能量多普勒血流灌注参数对胎盘植入性疾病的诊断价值

目的探讨超声评分法联合三维能量多普勒超声(3D power doppler ultrasonography,3D-PDU)诊断胎盘植入性疾病(placenta accreta,PAS)不同病理分型的应用价值。方法分析112例疑似PAS的孕妇,术前进行超声评分,并进行3D-PDU检查,测量血管指数(vascularization index,VI)、血流指数(flow index,FI)和血管-血流指数(vascularization flow index,VFI)。以病理诊断为金标准将样本分为不同组别,比较组间血流灌注参数的差异性。结果112例疑似PAS患者病理证实92例,PAS组VI、FI及VFI均高于无PAS组(P均<0.05)。92例PAS中未侵入肌层即粘连型24例,侵入肌层包括植入型和穿透型68例,侵入肌层组的VI、FI及VFI均高于非侵入肌层组(P均<0.05)。而植入型与穿透型比较时,穿透型的VI、VFI均高于植入型(P均<0.05)。采用超声评分法联合3D-PDU诊断粘连型、植入型以及穿透型胎盘植入的Kappa值分别为0.724、0.856和0.892。结论超声评分法与3D-PDU联合使用可定量分析胎盘血流灌注情况,为产前诊断PAS的精准分型提供量化评估依据。

早孕期三维能量多普勒联合频谱多普勒定量评估胎盘血流灌注预测胎儿生长受限的相关性

目的 分析早孕期三维能量多普勒联合频谱多普勒定量评估胎盘血流灌注预测胎儿生长受限(FGR)的相关性。方法 选取76例于天津中医药大学附属北辰中医医院2021年4月—2022年9月进行早孕期NT检查的孕妇为研究对象,根据胎儿是否存在生长受限分为对照组69例,FGR组7例。以此对比产妇基本资料,两组超声参数:胎盘血管化指数(VI)、胎盘血流指数(FI)、血管化-血流指数(VFI)、子宫动脉阻力指数(UtA-RI)、子宫动脉搏动指数(UtA-PI)、胎儿静脉导管搏动指数(DV-PI),分析发生FGR独立危险因素,超声参数与FGR的相关性,ROC曲线分析不同指标预测FGR的效能。结果 FGR与年龄、BMI指数、孕期贫血、产次无关,无统计学差异(P>0.05);主要与胎膜早破、羊水过少、脐带异常、胎粪污染、胎盘异常有关,具有统计学差异(P<0.05)。与对照组相比,FGR组VI、VFI、水平较低,UtA-RI、UtA-PI、DV-PI水平有所提升(P<0.05)。以FGR为因变量(0=否,1=是),建立Logistic回归模型,结果显示,VI、VFI、UtA-RI、UtA-PI、DV-PI是导致FGR的独立危险因素(P<0.05)。VI、VFI参数与FGR呈负相关;UtA-RI、UtA-PI、DV-PI参数与FGR呈正相关(P<0.05)。ROC曲线显示,VI、VFI、UtA-RI、UtA-PI、DV-PI单一及联合预测均有较高效能,而联合检查预测价值最高(P<0.05)。结论 早孕期采用三维能量多普勒联合频谱多普勒预测FGR的效能较高,有助于早期诊断并及时采取干预措施。

三维能量多普勒定量技术对乳腺癌组织学分级的预测价值探讨

目的探讨三维能量多普勒超声(3D-PDUS)中血管定量参数对乳腺癌组织学分级的预测价值。方法回顾性选择2018年1月至2023年6月在杭州市中医院行手术治疗的乳腺癌患者77例(恶性肿块86个),所有肿块均经病理组织学检查证实,根据组织学分级分为Ⅰ级组、Ⅱ级组、Ⅲ级组。比较3组患者年龄、常规超声检查所见、3D-PDUS指标。常规超声检查所见包括淋巴结转移、肿块内部钙化、肿块Adler血流分级;3D-PDUS指标包括肿块体积、血管参数[血管形成指数(VI)、血流指数(FI)、血管形成-血流指数(VFI)]。应用logistic回归分析乳腺癌组织学分级的危险因素。采用ROC曲线分析VI、FI、VFI对乳腺癌组织学分级的预测准确度。结果Ⅲ级组VI、FI、VFI高于Ⅱ级组,Ⅱ级组高于Ⅰ级组,差异均有统计学意义(均P<0.05)。其中FI为乳腺癌不同组织学分级的独立危险因素(P<0.001)。ROC曲线分析显示VI、FI、VFI对乳腺癌组织学分级的预测准确度均较高(AUC=0.888、0.891、0.894,均P<0.001)。结论3D-PDUS显示的VI、FI、VFI是瘤内血管化重要定量指标,可为乳腺癌患者组织学分级提供可靠的影像学预测信息。

融合卫星姿态的星地信道建模及硬件模拟

针对传统星地信道模型及其硬件模拟方法没有考虑卫星姿态对信道特性影响的问题,本文基于几何地理随机模型(Geometry-based Stochastic Model,GBSM)框架,提出了一种融合卫星姿态的星地信道模型。该模型通过构建四个独立的坐标系并引入姿态修正矩阵,来描述卫星姿态变化对星地信道特性造成的影响。在此基础上,本文基于现场可编程门阵列(Field Programmable Gate Array,FPGA),设计并研制了一种星地信道硬件模拟器。硬件模拟器采用差分迭代的算法来生成信道衰落因子,可以极大提高硬件模拟的实时性,确保生成的衰落数据与实际场景相匹配。同时,还采用了并行处理架构,可以支持最大640 MHz带宽的星地信道模拟。为了将衰落数据与并行架构相匹配,引入了并行内插算法,可以将串行的衰落数据内插成同速率的多路并行衰落数据。此外,为了能够精准控制硬件装置输出信号的功率,设计了基于预训练的功率校正方法。通过内部校正源信号预先训练出整个模拟过程给信号带来的增益再进行功率补偿,从而保证输出信号的功率可以被精准控制。最后,在典型场景下开展仿真模拟,导出硬件模拟器的输出结果并分析其统计特性,结果表明实测输出的概率密度函数(Probability Density Function,PDF)和多普勒功率谱密度(Doppler Power Spectral Density,DPSD)与理论值吻合,证明本文设计的硬件模拟器可以准确地复现实际场景下卫星姿态发生变化的星地信道。本文提出的融合卫星姿态的星地信道模型以及研制的硬件模拟器很好地解决了传统模型以及硬件模拟方法的局限性,在卫星通信系统的优化、评估和验证环节具有极大的潜在价值。

三维能量多普勒超声预测子宫腺肌病患者体外受精-胚胎移植后妊娠结局的临床价值

目的探讨经阴道三维能量多普勒超声(3D-PDUS)预测子宫腺肌病患者体外受精-胚胎移植(IVF-ET)后妊娠结局的临床价值。方法选取在我院接受IVF-ET的子宫腺肌病不孕患者100例(研究组),以及同期单纯不孕患者40例(对照组),均于IVF-ET前行经阴道3D-PDUS观察子宫内膜与肌层交界区(EMI)的形态,获取EMI平均厚度、容积及血管化指数(VI)、血流指数(FI)、血管化血流指数(VFI),比较两组上述参数的差异。记录研究组患者妊娠结局,比较妊娠患者与未妊娠患者EMI形态、平均厚度、容积及VI、FI、VFI的差异。采用二元Logistic回归分析筛选子宫腺肌病患者IVF-ET后妊娠结局的独立影响因素;绘制受试者工作特征(ROC)曲线分析经阴道3D-PDUS预测子宫腺肌病患者IVF-ET后妊娠结局的诊断效能。结果研究组EMI形态正常占比、FI均低于对照组,差异均有统计学意义(均P<0.05);两组EMI平均厚度、容积及VI、VFI比较差异均无统计学意义。研究组患者接受IVF-ET后成功妊娠60例,未妊娠40例;妊娠患者EMI形态正常占比、平均厚度、容积及VI、FI、VFI均高于未妊娠患者,差异均有统计学意义(均P<0.001)。二元Logistic回归分析显示,EMI容积和VFI均为子宫腺肌病患者IVF-ET后妊娠结局的独立影响因素(OR=4.725、2.160,均P<0.05)。ROC曲线分析显示,EMI容积和VFI预测子宫腺肌病患者IVF-ET后妊娠结局的曲线下面积分别为0.795和0.672,对应的截断值分别为3.085 cm3和0.597。结论经阴道3D-PDUS能较好地预测子宫腺肌病患者IVF-ET后妊娠结局,具有一定的临床价值。

OFDM通信系统中的一种最大Doppler频移估计算法

在分析了已有各种Doppler估计算法的基础上,根据功率谱估计经典算法——窗函数法的原理,直接利用接收到的频域中连续导频信号,进行最大Doppler频移估计。该算法同时适合于单载波和多载波系统。仿真结果均表明:在单径和多径条件下,该算法均可对正交频分复用(OFDM)传输系统中的最大Doppler频移获得较精确的估计结果。该算法十分适合于OFDM移动通信系统。