AIM: To investigate the efficacy of Ferrara rings (FR) implantation in the treatment of keratoconus.METHODS: It was a retrospective case series descriptive study. The sample was comprised of 50 patients 79 eyes diagno...AIM: To investigate the efficacy of Ferrara rings (FR) implantation in the treatment of keratoconus.METHODS: It was a retrospective case series descriptive study. The sample was comprised of 50 patients 79 eyes diagnosed with progressive keratoconus. This included 24 (48%) males and 26 (52%) females between the age of 13 and 44 years. All participants underwent surgical implantation of FR in the period between January 2009 and September 2010 at Jordan University Hospital. Thorough ophthalmologic examinations were applied to measure vital variables for each pathological condition before and after surgery. RESULTS: Findings indicated an overall significant postoperative improvement in both uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA) throughout follow up visits. Moreover, results illustrated a significant decrease in spherical equivalent (SE) and keratometric readings (lower, higher and the average). CONCLUSION: Surgical intervention strategies are being frequently developed to meet the needs of patients with keratoconus. The implantation of Ferrara rings has proven to be a safe and feasible alternative procedure for the treatment of mild-moderate keratoconus especially for patients with contact lenses intolerance. We have found that this procedure has improved visual outcomes in all eyes studied. Nevertheless, further research is needed to investigate long term outcomes.展开更多
AIM:To evaluate the clinical results after implantation of a new intrastromal corneal ring segment(ICRS)associated with photorefractive keratectomy(PRK)to correct high myopia(HM)patients with thin corneas.METHODS:We e...AIM:To evaluate the clinical results after implantation of a new intrastromal corneal ring segment(ICRS)associated with photorefractive keratectomy(PRK)to correct high myopia(HM)patients with thin corneas.METHODS:We evaluated 42 eyes of 23 HM patients that had ICRS implantation followed by PRK.The mean age of patients was 29.1±7.12 y(range 18 to 40 years old).Uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),keratometry,spherical equivalent,pachymetry,and aberrometry were compared using ANOVA with repeated measurements evaluated preoperatively and at last follow-up visit after the procedures.The refractive predictability and simulated/real corneal ablation were also assessed.RESULTS:The mean follow-up time after PRK was 6.8±1.6 mo.The mean preoperative UCVA improved from 20/800 preoperative to 20/100 after ICRS and 20/35 after PRK.The mean preoperative BCVA was 20/25(range from 20/30 to 20/20)and remained unchanged after ICRS implantation.Following the PRK the mean BCVA was 20/25(range from 20/30 to 20/20).The mean spherical equivalent decreased from-7.25±1.12(range-5.00 to-9.00)preoperatively to-3.32±1.0(range-2.00 to-5.00)postoperatively(P<0.001)after ICRS implantation and decreased from-2.44±1.51 preoperatively to 0.32±0.45(range-0.625 to 0.875)postoperatively(P<0.001)after PRK.The change in BCVA and topographic astigmatism was statistically significant(P<0.0001).CONCLUSION:ICRS in HM associated with PRK can be a tissue saving procedure and an alternative surgical option for correction of moderate to high myopia.展开更多
AIM:To evaluate the clinical outcomes after Ferrara intrastromal corneal ring segments(ICRS)reoperation in patients with keratoconus.METHODS:A total of 37 keratoconus eyes implanted with intrastromal corneal ring segm...AIM:To evaluate the clinical outcomes after Ferrara intrastromal corneal ring segments(ICRS)reoperation in patients with keratoconus.METHODS:A total of 37 keratoconus eyes implanted with intrastromal corneal ring segments,which had an ICRS exchange,addition,reposition or removal were evaluated.Uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),keratometry(K),asphericity(Q)and pachymetry at the thinnest point(PTP)of the cornea were evaluated using a corneal tomography(Oculus Pentacam,USA)RESULTS:The mean follow-up time after the reoperation was 30.5±9.7 months.The mean UCVA improved from 20/300 to 20/80(P=0.005);the mean BCVA improved from 20/160 to 20/50(P=0.0002),the mean keratometry reduced from 49.33±4.19D to 46.16±3.90D(P=0.0001),the mean pachymetry at the thinnest point increased from 450±42.9μm to 469±40.8μm(P=0.0001).The asphericity increased from-0.84±0.74 to-0.35±0.81(P=0.15)and the spherical equivalent reduced from-4.64±4.87D to-3.04±3.45D(P=0.137).The changes in the asphericity and spherical equivalent were not statistically significant.CONCLUSION:Ferrara ICRS implantation showed to be a reversible and readjustable surgical procedure for keratoconus treatment.Good outcomes can be obtained even after removal,addition,reposition or exchange of ICRS.展开更多
· AIM: To evaluate and compare the efficacy and stability of intrastromal corneal ring segment(ICRs)implantation with cross-linking(CXL) using different sequence and timing.· METHODS: In this single retrospe...· AIM: To evaluate and compare the efficacy and stability of intrastromal corneal ring segment(ICRs)implantation with cross-linking(CXL) using different sequence and timing.· METHODS: In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups.They were divided into three groups: ICRs implantation was applied only(group normal), ICRs first followed by CXL immediately(group CXL-S), CXL first followed by ICRs long after(group CXL-B). The visual acuity,refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.·RESULTS: Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity(UDVA) and the mean corrected distance visual acuity(CDVA) compared preoperatively and 1y postoperatively [UDVA: 0.31(P =0.030) logarithmic minimum angle of resolution(log MAR) group normal, 0.4(P =0.020) group CXL-S, 0.45(P =0.001) group CXL-B;CDVA : 0. 21 log MAR( P = 0. 013) group normal, 0. 30(P =0.036) group CXL-S; 0.26(P =0.000) group CXL-B].The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.·CONCLUSION: With safety and good visual outcomes,ICRs implantation is a viable alternative for keratoconus.No significant difference was found among these three groups.展开更多
AIM:To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data.METHODS:This prospecti...AIM:To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data.METHODS:This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients(age 18-62 y)with keratoconus diagnosis from two Spanish centers.Ferrara ring segment(AJL Ophthalmic)implantation was performed in all cases,using the mechanical procedure in 25 eyes(28.4%)and a femtosecond laser-assisted procedure in 63 eyes(71.6%).The ring segments implanted in each case were selected using a new optimized nomogram that considered variables such as anterior corneal asphericity and astigmatism or the discrepancy among astigmatism and coma orientations.Visual,refractive,corneal topographic,aberrometric,and pachymetric changes after surgery were evaluated during a 3-month follow-up.RESULTS:The implants induced a significant refractive change as well as an improvement in uncorrected(UDVA)and corrected distance visual acuity(CDVA;P<0.001).Postoperative CDVA of 0.10 log MAR or better was achieved in 28.4%and 46.5%of eyes,respectively.Two eyes(2.3%)lost two or more lines of CDVA whereas a total of 53.5%of eyes gained lines of CDVA.A significant central anterior and posterior corneal flattening was induced(P≤0.003),with a significant reduction of anterior(P<0.001)and posterior corneal astigmatisms(P=0.048),and a change in anterior asphericity(P<0.001).Total primary coma(6 mm pupil)change was also statistically significant(preoperative 3.66±3.04μm vs postoperative 2.33±2.26μm,P<0.001).No significant differences were found in the effect of ring segments between cases implanted using the mechanical and femtosecond techniques(P≥0.101).CONCLUSION:The implantation of Ferrara rings based on the nomogram evaluated is safe and effective for promoting a visual rehabilitation in keratoconus,with a relevant control of primary coma aberration.展开更多
AIM:To evaluate the clinical outcomes after subsequent implantation of a new intrastromal corneal ring segment(ICRS)model followed by an additional short-arc ICRS implant in keratoconus patients.METHODS:This retrospec...AIM:To evaluate the clinical outcomes after subsequent implantation of a new intrastromal corneal ring segment(ICRS)model followed by an additional short-arc ICRS implant in keratoconus patients.METHODS:This retrospective single-arm cohort study evaluated 25 eyes of 21 keratoconus patients implanted with the new ICRS followed by 140-arch length ICRS(140-ICRS)implantation.Uncorrected distance visual acuity(UDVA,logMAR),corrected distance visual acuity(CDVA,logMAR),sphere,astigmatism,keratometry,spherical equivalent(SE),and asphericity were compared preoperatively and postoperatively after both ICRS implantation.RESULTS:The average follow-up time after 140-ICRS implantation was 6.40±2.20mo.The mean preoperative UDVA improved from 1.27±0.14 preoperative to 0.52±0.26 after both ICRS implantation(P=0.03).The mean sphere value reduced from-5.34±2.74 preoperatively to-2.06±1.84 postoperatively(P<0.001)after the first ICRS implantation and decreased to-0.59±1.54 postoperatively(P<0.001)after 140-ICRS implantation.The mean preoperative astigmatism was-3.72±1.56 and improved to-2.82±1.08 after the first ICRS implantation,and following the 140-ICRS implantation,the mean astigmatism was-1.37±0.67(P=0.001).The SE and asphericity changes were statistically significant(P<0.001).The researchers did not find intraoperative or postoperative complications for both procedures.CONCLUSION:The combination of 2 different ICRSs can efficiently regularize the cornea,reduce the SE,and improve visual acuity in selected keratoconus patients.展开更多
AIM：To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment（ICRS） with 140-degrees of arc in eyes with corneal ectasia.METHODS：We evaluated patients with cor...AIM：To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment（ICRS） with 140-degrees of arc in eyes with corneal ectasia.METHODS：We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015.Outcome measures included preoperative and postoperative corrected distance visual acuity（CDVA）,keratometry simulated（K） reading,tomographic astigmatism and asphericity.All patients were evaluated using the Pentacam Scheimpflug system.RESULTS：The study evaluated 58 eyes.The mean followup was 16.81±10.8 mo.The CDVA（logM AR） improved from 0.5±0.20（20/60） to 0.3±0.21（20/40）（P〈0.01）.The average K reduced from 49.87±7.01 to 47.34±4.90 D（P〈0.01）.The asphericity changed from-0.60±0.86 to-0.23±0.67 D（P〈0.01）.The mean preoperative tomographic astigmatism decreased from-8.0±3.45 to-4.53±2.52 D（P〈0.01）.CONCLUSION：The new ICRS model with 140-degrees of arc effectively improve the visual acuity and reduce the high astigmatism usually found in patients with corneal ectasia.展开更多
The uniform ring model and the shell-spring model for segmental lining design are reviewed in thisarticle. The former is the most promising means to reflect the real behavior of segmental lining, while thelatter is th...The uniform ring model and the shell-spring model for segmental lining design are reviewed in thisarticle. The former is the most promising means to reflect the real behavior of segmental lining, while thelatter is the most popular means in practice due to its simplicity. To understand the relationship and thedifference between these two models, both of them are applied to the engineering practice of FuzhouMetro Line I, where the key parameters used in both models are described and compared. The effectiveratio of bending rigidity h reflecting the relative stiffness between segmental lining and surroundingground and the transfer ratio of bending moment x reflecting the relative stiffness between segment andjoint, which are two key parameters used in the uniform ring model, are especially emphasized. Thereasonable values for these two key parameters are calibrated by comparing the bending momentscalculated from both two models. Through case studies, it is concluded that the effective ratio of bendingrigidity h increases significantly with good soil properties, increases slightly with increasing overburden,and decreases slightly with increasing water head. Meanwhile, the transfer ratio of bending moment xseems to only relate to the properties of segmental lining itself and has a minor relation with the groundconditions. These results could facilitate the design practice for Fuzhou Metro Line I, and could alsoprovide some references to other projects with respect to similar scenarios.展开更多
在气候学、生态学、考古学等诸多领域,树木年轮蕴含的环境变迁与历史演替信息具有不可替代的研究价值。为解决传统年轮检测方法存在效率低、易受人为因素干扰等问题,研究提出DCW-YOLOv8年轮实例分割模型,运用可扩张残差(Dilation-wise R...在气候学、生态学、考古学等诸多领域,树木年轮蕴含的环境变迁与历史演替信息具有不可替代的研究价值。为解决传统年轮检测方法存在效率低、易受人为因素干扰等问题,研究提出DCW-YOLOv8年轮实例分割模型,运用可扩张残差(Dilation-wise Residual,DWR)注意力模块、轻量级通用上采样算子(Content-Aware ReAssembly of Features,CARAFE)、动态非单调聚焦机制边界框损失函数(Weighted Interpolation of Sequential Evidence for Intersection over Union,Wise-IoU)组合改进,并设计一种依据模型掩码获取年轮数量与宽度信息的检测方法。消融试验和前沿模型对比试验结果表明,DCWYOLOv8模型掩码平均精度mAP@0.50、mAP@0.50∶0.95提升,达到86.4%、53.6%,优于同类算法;注意力可视化比较结果表明,DCW-YOLOv8对年轮特征注意力更强;年轮信息检测结果表明,年轮数量检测准确率达到86.2%,年轮宽度检测误差在±0.5 mm范围内的占70%,总体平均误差为0.295 mm。研究提出的DCW-YOLOv8模型为年轮自动化检测提供新的思路和方法。展开更多
文摘AIM: To investigate the efficacy of Ferrara rings (FR) implantation in the treatment of keratoconus.METHODS: It was a retrospective case series descriptive study. The sample was comprised of 50 patients 79 eyes diagnosed with progressive keratoconus. This included 24 (48%) males and 26 (52%) females between the age of 13 and 44 years. All participants underwent surgical implantation of FR in the period between January 2009 and September 2010 at Jordan University Hospital. Thorough ophthalmologic examinations were applied to measure vital variables for each pathological condition before and after surgery. RESULTS: Findings indicated an overall significant postoperative improvement in both uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA) throughout follow up visits. Moreover, results illustrated a significant decrease in spherical equivalent (SE) and keratometric readings (lower, higher and the average). CONCLUSION: Surgical intervention strategies are being frequently developed to meet the needs of patients with keratoconus. The implantation of Ferrara rings has proven to be a safe and feasible alternative procedure for the treatment of mild-moderate keratoconus especially for patients with contact lenses intolerance. We have found that this procedure has improved visual outcomes in all eyes studied. Nevertheless, further research is needed to investigate long term outcomes.
文摘AIM:To evaluate the clinical results after implantation of a new intrastromal corneal ring segment(ICRS)associated with photorefractive keratectomy(PRK)to correct high myopia(HM)patients with thin corneas.METHODS:We evaluated 42 eyes of 23 HM patients that had ICRS implantation followed by PRK.The mean age of patients was 29.1±7.12 y(range 18 to 40 years old).Uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),keratometry,spherical equivalent,pachymetry,and aberrometry were compared using ANOVA with repeated measurements evaluated preoperatively and at last follow-up visit after the procedures.The refractive predictability and simulated/real corneal ablation were also assessed.RESULTS:The mean follow-up time after PRK was 6.8±1.6 mo.The mean preoperative UCVA improved from 20/800 preoperative to 20/100 after ICRS and 20/35 after PRK.The mean preoperative BCVA was 20/25(range from 20/30 to 20/20)and remained unchanged after ICRS implantation.Following the PRK the mean BCVA was 20/25(range from 20/30 to 20/20).The mean spherical equivalent decreased from-7.25±1.12(range-5.00 to-9.00)preoperatively to-3.32±1.0(range-2.00 to-5.00)postoperatively(P<0.001)after ICRS implantation and decreased from-2.44±1.51 preoperatively to 0.32±0.45(range-0.625 to 0.875)postoperatively(P<0.001)after PRK.The change in BCVA and topographic astigmatism was statistically significant(P<0.0001).CONCLUSION:ICRS in HM associated with PRK can be a tissue saving procedure and an alternative surgical option for correction of moderate to high myopia.
文摘AIM:To evaluate the clinical outcomes after Ferrara intrastromal corneal ring segments(ICRS)reoperation in patients with keratoconus.METHODS:A total of 37 keratoconus eyes implanted with intrastromal corneal ring segments,which had an ICRS exchange,addition,reposition or removal were evaluated.Uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),keratometry(K),asphericity(Q)and pachymetry at the thinnest point(PTP)of the cornea were evaluated using a corneal tomography(Oculus Pentacam,USA)RESULTS:The mean follow-up time after the reoperation was 30.5±9.7 months.The mean UCVA improved from 20/300 to 20/80(P=0.005);the mean BCVA improved from 20/160 to 20/50(P=0.0002),the mean keratometry reduced from 49.33±4.19D to 46.16±3.90D(P=0.0001),the mean pachymetry at the thinnest point increased from 450±42.9μm to 469±40.8μm(P=0.0001).The asphericity increased from-0.84±0.74 to-0.35±0.81(P=0.15)and the spherical equivalent reduced from-4.64±4.87D to-3.04±3.45D(P=0.137).The changes in the asphericity and spherical equivalent were not statistically significant.CONCLUSION:Ferrara ICRS implantation showed to be a reversible and readjustable surgical procedure for keratoconus treatment.Good outcomes can be obtained even after removal,addition,reposition or exchange of ICRS.
文摘· AIM: To evaluate and compare the efficacy and stability of intrastromal corneal ring segment(ICRs)implantation with cross-linking(CXL) using different sequence and timing.· METHODS: In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups.They were divided into three groups: ICRs implantation was applied only(group normal), ICRs first followed by CXL immediately(group CXL-S), CXL first followed by ICRs long after(group CXL-B). The visual acuity,refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.·RESULTS: Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity(UDVA) and the mean corrected distance visual acuity(CDVA) compared preoperatively and 1y postoperatively [UDVA: 0.31(P =0.030) logarithmic minimum angle of resolution(log MAR) group normal, 0.4(P =0.020) group CXL-S, 0.45(P =0.001) group CXL-B;CDVA : 0. 21 log MAR( P = 0. 013) group normal, 0. 30(P =0.036) group CXL-S; 0.26(P =0.000) group CXL-B].The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.·CONCLUSION: With safety and good visual outcomes,ICRs implantation is a viable alternative for keratoconus.No significant difference was found among these three groups.
基金Supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal (RYC-2016-20471)
文摘AIM:To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data.METHODS:This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients(age 18-62 y)with keratoconus diagnosis from two Spanish centers.Ferrara ring segment(AJL Ophthalmic)implantation was performed in all cases,using the mechanical procedure in 25 eyes(28.4%)and a femtosecond laser-assisted procedure in 63 eyes(71.6%).The ring segments implanted in each case were selected using a new optimized nomogram that considered variables such as anterior corneal asphericity and astigmatism or the discrepancy among astigmatism and coma orientations.Visual,refractive,corneal topographic,aberrometric,and pachymetric changes after surgery were evaluated during a 3-month follow-up.RESULTS:The implants induced a significant refractive change as well as an improvement in uncorrected(UDVA)and corrected distance visual acuity(CDVA;P<0.001).Postoperative CDVA of 0.10 log MAR or better was achieved in 28.4%and 46.5%of eyes,respectively.Two eyes(2.3%)lost two or more lines of CDVA whereas a total of 53.5%of eyes gained lines of CDVA.A significant central anterior and posterior corneal flattening was induced(P≤0.003),with a significant reduction of anterior(P<0.001)and posterior corneal astigmatisms(P=0.048),and a change in anterior asphericity(P<0.001).Total primary coma(6 mm pupil)change was also statistically significant(preoperative 3.66±3.04μm vs postoperative 2.33±2.26μm,P<0.001).No significant differences were found in the effect of ring segments between cases implanted using the mechanical and femtosecond techniques(P≥0.101).CONCLUSION:The implantation of Ferrara rings based on the nomogram evaluated is safe and effective for promoting a visual rehabilitation in keratoconus,with a relevant control of primary coma aberration.
文摘AIM:To evaluate the clinical outcomes after subsequent implantation of a new intrastromal corneal ring segment(ICRS)model followed by an additional short-arc ICRS implant in keratoconus patients.METHODS:This retrospective single-arm cohort study evaluated 25 eyes of 21 keratoconus patients implanted with the new ICRS followed by 140-arch length ICRS(140-ICRS)implantation.Uncorrected distance visual acuity(UDVA,logMAR),corrected distance visual acuity(CDVA,logMAR),sphere,astigmatism,keratometry,spherical equivalent(SE),and asphericity were compared preoperatively and postoperatively after both ICRS implantation.RESULTS:The average follow-up time after 140-ICRS implantation was 6.40±2.20mo.The mean preoperative UDVA improved from 1.27±0.14 preoperative to 0.52±0.26 after both ICRS implantation(P=0.03).The mean sphere value reduced from-5.34±2.74 preoperatively to-2.06±1.84 postoperatively(P<0.001)after the first ICRS implantation and decreased to-0.59±1.54 postoperatively(P<0.001)after 140-ICRS implantation.The mean preoperative astigmatism was-3.72±1.56 and improved to-2.82±1.08 after the first ICRS implantation,and following the 140-ICRS implantation,the mean astigmatism was-1.37±0.67(P=0.001).The SE and asphericity changes were statistically significant(P<0.001).The researchers did not find intraoperative or postoperative complications for both procedures.CONCLUSION:The combination of 2 different ICRSs can efficiently regularize the cornea,reduce the SE,and improve visual acuity in selected keratoconus patients.
文摘AIM：To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment（ICRS） with 140-degrees of arc in eyes with corneal ectasia.METHODS：We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015.Outcome measures included preoperative and postoperative corrected distance visual acuity（CDVA）,keratometry simulated（K） reading,tomographic astigmatism and asphericity.All patients were evaluated using the Pentacam Scheimpflug system.RESULTS：The study evaluated 58 eyes.The mean followup was 16.81±10.8 mo.The CDVA（logM AR） improved from 0.5±0.20（20/60） to 0.3±0.21（20/40）（P〈0.01）.The average K reduced from 49.87±7.01 to 47.34±4.90 D（P〈0.01）.The asphericity changed from-0.60±0.86 to-0.23±0.67 D（P〈0.01）.The mean preoperative tomographic astigmatism decreased from-8.0±3.45 to-4.53±2.52 D（P〈0.01）.CONCLUSION：The new ICRS model with 140-degrees of arc effectively improve the visual acuity and reduce the high astigmatism usually found in patients with corneal ectasia.
基金sponsored by the Natural Science Foundation of China(Grant No.51008082)
文摘The uniform ring model and the shell-spring model for segmental lining design are reviewed in thisarticle. The former is the most promising means to reflect the real behavior of segmental lining, while thelatter is the most popular means in practice due to its simplicity. To understand the relationship and thedifference between these two models, both of them are applied to the engineering practice of FuzhouMetro Line I, where the key parameters used in both models are described and compared. The effectiveratio of bending rigidity h reflecting the relative stiffness between segmental lining and surroundingground and the transfer ratio of bending moment x reflecting the relative stiffness between segment andjoint, which are two key parameters used in the uniform ring model, are especially emphasized. Thereasonable values for these two key parameters are calibrated by comparing the bending momentscalculated from both two models. Through case studies, it is concluded that the effective ratio of bendingrigidity h increases significantly with good soil properties, increases slightly with increasing overburden,and decreases slightly with increasing water head. Meanwhile, the transfer ratio of bending moment xseems to only relate to the properties of segmental lining itself and has a minor relation with the groundconditions. These results could facilitate the design practice for Fuzhou Metro Line I, and could alsoprovide some references to other projects with respect to similar scenarios.
文摘在气候学、生态学、考古学等诸多领域,树木年轮蕴含的环境变迁与历史演替信息具有不可替代的研究价值。为解决传统年轮检测方法存在效率低、易受人为因素干扰等问题,研究提出DCW-YOLOv8年轮实例分割模型,运用可扩张残差(Dilation-wise Residual,DWR)注意力模块、轻量级通用上采样算子(Content-Aware ReAssembly of Features,CARAFE)、动态非单调聚焦机制边界框损失函数(Weighted Interpolation of Sequential Evidence for Intersection over Union,Wise-IoU)组合改进,并设计一种依据模型掩码获取年轮数量与宽度信息的检测方法。消融试验和前沿模型对比试验结果表明,DCWYOLOv8模型掩码平均精度mAP@0.50、mAP@0.50∶0.95提升,达到86.4%、53.6%,优于同类算法;注意力可视化比较结果表明,DCW-YOLOv8对年轮特征注意力更强;年轮信息检测结果表明,年轮数量检测准确率达到86.2%,年轮宽度检测误差在±0.5 mm范围内的占70%,总体平均误差为0.295 mm。研究提出的DCW-YOLOv8模型为年轮自动化检测提供新的思路和方法。
