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Orthokeratology with increased compression factor in adolescent myopia control:a 2-year prospective randomized clinical trial

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International Journal of Ophthalmology(English edition) 2023年第5期16卷 770-777页

作者： Wen-Ting Tang Li Zhang Hui-Dan Zhang Shi-Bei Li Hao Liang Department of Ophthalmology the First Affiliated Hospital of Guangxi Medical UniversityNanning 530021Guangxi Zhuang Autonomous RegionChina Department of Ophthalmology the First Affiliated Hospital of Chengdu Medical CollegeChengdu 610500Sichuan ProvinceChina

AIM:To explore the long-term efficacy,safety,and optical mechanism of orthokeratology with increased compression factor in adolescent myopia ***:A prospective,double-masked,and randomized clinical trial was performed from May 2016 to June *** aged between 8 and 16y,with myopia(-5.00 to-1.00 D),low astigmatism(≥-1.50 D)and anisometropia(≤1.00 D),were stratified into low(-2.75 to-1.00 D)and moderate(-5.00 to-3.00 D)myopia *** they were randomly assigned to wear either increased compression factor(ICF;1.75 D)orthokeratology or conventional compression factor(CCF;0.75 D)*** data were recorded including axial length(AL),spherical equivalent(SE),best corrected visual acuity(BCVA),near visual acuity(NVA),corneal staining(using Efron grading scales),corneal hysteresis(CH),corneal resistance factor(CRF),higher-order aberrations(HOAs,expressed as root mean square,RMS_(h)),and subfoveal choroidal thickness(SFCh T)in the 2-year followup ***'s correlation coefficient was conducted to analyze the association between the changes in AL and RMS_(h),SFCh ***:At the 2-year visit,there were no statistical differences in all the parameters between the ICF group and the CCF group in low myopia subjects(P>0.05).For the moderate myopia subjects,the ICF group had shorter AL elongation(0.23±0.08 vs 0.30±0.11 mm,P=0.015),higher RMS_(h)(1.94±0.50 vs 1.65±0.51μm,P=0.041),and higher SFCh T(279.04±35.72 vs 254.08±29.60μm,P=0.008)than those in CCF *** change in AL was negatively correlated with RMS_(h)(r=-0.687,P<0.001)and SFCh T(r=-0.464,P=0.013).CONCLUSION:ICF orthokeratology can control the progression of moderate myopia more effectively,which might be related to greater RMS_(h) and SFCh T.

关键词： orthokeratology compression factor myopia axial length higher-order aberrations choroidal thickness

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Altering optical zone diameter, reverse curve width, and compression factor: impacts on visual performance and axial elongation in orthokeratology

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CONTACT LENS & ANTERIOR EYE 2024年第3期47卷 102136-102136页

作者： Wu, Jinfang Zhang, Xinyu Wang, Linlin Zhang, Peipei Guo, Xi Xie, Peiying Capital Med Univ Beijing Tongren Hosp Beijing Inst Ophthalmol Beijing Tongren Eye Ctr Beijing 100730 Peoples R China Wenzhou Med Univ Eye Hosp Wenzhou 325027 Peoples R China Beijing Internet Eyecare Optometry & Ophthalmol Cl Beijing 100027 Peoples R China

Purpose: To investigate the effects of modifications in back optical zone diameter (BOZD), reverse curve width (RCW), and compression factor (CF) on refractive error changes and axial elongation in myopic children undergoing orthokeratology (ortho-k) over a 12-month period. Method: In this retrospective study, data from 126 myopic children undergoing ortho-k fitting were analyzed. Subjects were categorized into four distinct groups based on lens design parameters: Group A (BOZD 6.0 mm, RCW 0.6 mm, CF 0.75 D);Group B (BOZD 6.0 mm, RCW 0.6 mm, CF 1.25 D);Group C (BOZD 5.4 mm, RCW 0.9 mm, CF 1.25 D);and Group D (BOZD 5.0 mm, RCW 1.1 mm, CF 1.25 D). The study evaluated uncorrected visual acuity (UCVA), corneal topography, and axial length (AL) at intervals, using Linear Mixed Models (LMMs) for time-based changes, and ANOVA or Kruskal-Wallis tests for group differences in AL elongation. A multivariable regression analysis identified factors independently associated with AL elongation. Results: Within the first day and week, all four groups displayed significant improvements in UCVA and alterations in corneal curvature, which subsequently stabilized. Although UCVA variations between groups were subtle, Group D had less corneal curvature change than Groups A and B initially and exhibited significantly less AL elongation after one year. No significant difference in corneal curvature change or AL elongation was observed between Group C and the other groups. Multiple regression analysis indicated that older baseline age, greater baseline spherical equivalent refractive error, and smaller BOZD were associated with less AL elongation. Conclusion: The study reveals a positive correlation between BOZD and axial length growth over the 12-month period. A pure 0.5 D CF increment demonstrates a nonsignificant impact. This study provides new ideas into optimizing the parameters of ortho-k lenses.

关键词： Orthokeratology Myopia control Back optic zone diameter Reverse curve compression factor

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Influence of fabric orientation and compression factor on the mechanical properties of 3D E-glass reinforced epoxy composites

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JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T 2020年第4期9卷 8517-8527页

作者： Nayak, Suhas Yeshwant Satish, Shenoy B. Sultan, Mohamed Thariq Hameed Kini, Chandrakant R. Shenoy, K. Rajath Samant, Rashmi Sarvade, Praneeth P. Basri, Adi Azriff Mustapha, Faizal Manipal Acad Higher Educ Manipal Inst Technol Dept Mech & Mfg Engn Manipal 576104 Karnataka India Manipal Acad Higher Educ Manipal Inst Technol Dept Aeronaut & Automobile Engn Manipal 576104 Karnataka India Inst Trop Forestry & Forest Prod INTROP Lab Biocomposite Technol Upm Serdang 43400 Selangor Darul Malaysia Univ Putra Malaysia Fac Engn Dept Aerosp Engn Upm Serdang 43400 Selangor Darul Malaysia Aerosp Malaysia Innovat Ctr 944751A MIGHT Partnership Hub Prime Ministers Dept Jalan Impact Cyberjaya 63000 Selangor Darul Malaysia

3-D E-glass fabric reinforced epoxy composites at 6 mm thickness were fabricated for various orientations of the binder yarn viz. 0, 30, 45, 60 and 90 respectively. Tensile, flexural, interlaminar shear stress tests were conducted to ascertain the influence of binder yarn orientation on the mechanical properties of the composites. The composites with 0 binder yarn orientation showed the best strength followed by 90 whilst the others showed highly depleted traits in comparison. Shear stress induced at the interface of each lamina was seen as the major reason for drop in the strength. A secondary study was carried out to explore the effect of compression factor during fabrication on the mechanical properties of the composites. Laminates with varying thickness namely, 4 mm, 5 mm and 7 mm but, with same number of plies of 3D E-glass fabric at 0 orientation were fabricated. The test results were compared with the results of 6 mm composites from the primary study. The results showed that, compression factor affected the mechanical properties of the composites and had a direct relation with increasing compression factor up to a certain value beyond which a drop in properties was seen. Composites pressed to a thickness of 5 mm showed the best properties. Drop in properties was attributed to close packing of reinforcement and crushing of fibres leading to inefficient stress transfer. Scanning electron microscopy was employed to understand the modes of failure. The major failure modes observed were delamination, matrix cracking and debonding. Based on the results obtained, these composites can be seen as a material system for applications like ballistic armours, structural renovations and automobile components. (C) 2020 The Author(s). Published by Elsevier B.V.

关键词： 3D E-glass fabric Fabric orientation Hand lay-up compression moulding compression factor Mechanical properties

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The influence of orthokeratology compression factor on ocular higher-order aberrations

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CLINICAL AND EXPERIMENTAL OPTOMETRY 2020年第1期103卷 123-128页

作者： Lau, Jason K. Vincent, Stephen J. Cheung, Sin-Wan Cho, Pauline Hong Kong Polytech Univ Ctr Myopia Res Sch Optometry Hong Kong Peoples R China Queensland Univ Technol Sch Optometry & Visual Sci Contact Lens & Visual Opt Lab Brisbane Qld Australia

Background To investigate the influence of compression factor upon changes in ocular higher-order aberrations (HOAs) in young myopic children undergoing orthokeratology treatment. Methods Subjects aged between six and < 11 years, with low myopia (0.50-4.00 D inclusive), low astigmatism (<= 1.25 D), and anisometropia (<= 1.00 D), were randomly assigned to wear orthokeratology lenses of different compression factors in each eye (one eye 0.75 D and the fellow eye 1.75 D). HOAs were measured weekly over one month of lens wear. Wavefront analysis was conducted over a 5-mm pupil using a sixth order Zernike polynomial expansion. Linear mixed models were used to examine the individual Zernike co-efficients and specific root-mean-square (RMS) error (spherical, comatic, total HOAs) metrics and their changes between the two eyes during the study period. Results Twenty-eight myopic (mean manifest spherical equivalent refraction: -2.10 +/- 0.58 D) children (median [range] age: 9.3 [7.8-11.0] years) were analysed. Significant interocular differences in HOAs at baseline were observed for Z6-6 and Z6-4 only (both p < 0.05). During the lens wear period, eyes fitted with the increased compression factor showed greater changes in primary spherical aberration (Z40, p = 0.04) and RMS values for spherical and total HOAs (both p < 0.01). Considering data from both eyes together, after adjusting for the paired nature of the data, some other Zernike terms (Z31 and Z60, both p < 0.01) and the RMS value of comatic aberrations (p < 0.001) significantly increased after one month of orthokeratology treatment. The increase in primary spherical aberration (Z40) was positively correlated with the reduction in spherical equivalent refractive error, but only in eyes fitted with the increased compression factor (r = 0.69, p < 0.001). Conclusions Increasing the orthokeratology compression factor by 1.00 D significantly altered some HOAs, particularly spherical aberration. Given the association between

关键词： compression factor higher-order aberrations orthokeratology

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Particle swarm optimization algorithm with compression factor is used to solve complex shading MPPT problem

Particle swarm optimization algorithm with compression facto...

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作者： Yanping Wang Zhen Zhang School of Electrical Engineering Zhengzhou University

In photovoltaic power generation systems, pv arrays are often affected by local shadow phenomena, resulting in the unstable operation of the system and the reduction of output power. In addition, pv array's p-u characteristic curve will show multiple peaks, and the traditional maximum power point tracking(MPPT) algorithm cannot complete the tracking of the maximum power point because it can only find the single peak. Particle swarm optimization(PSO) algorithm has good global optimization ability of multi-peak, which is widely used in tracking the maximum power point of local shadow. However, PSO algorithm has the shortcoming of insufficient convergence speed and low search accuracy. Therefore, a particle swarm optimization(YSPSO) algorithm with compression factor is proposed to effectively improve the global search ability and local improvement ability of the whole algorithm.

关键词： MPPT problem Particle swarm optimization algorithm compression factor

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Investigation on the Compressibility factor of Hydrogen-Doped Natural Gas Using GERG-2008 Equation of State

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ENERGIES 2025年第1期18卷 53-53页

作者： Li, Ji-Chao Fan, Yong Pang, Dan Wu, Tong Zhang, Ying Zhou, Ke Jining Univ Sch Mech & Elect Engn Qufu 273155 Peoples R China Ludong Univ Sch Transportat Yantai 264025 Peoples R China Liaoshen Ind Grp Co Ltd Shenyang 110045 Peoples R China

The primary methods for hydrogen transportation include gaseous storage and transport, liquid hydrogen storage, and transport via organic liquid carriers. Among these, pipeline transportation offers the lowest cost and the greatest potential for large-scale, long-distance transport. Although the construction and operation costs of dedicated hydrogen pipelines are relatively high, blending hydrogen into existing natural gas networks presents a viable alternative. This approach allows hydrogen to be transported to the end-users, where it can be either separated for use or directly combusted, thereby reducing hydrogen transport costs. This study, based on the GERG-2008 equation of state, conducts experimental tests on the compressibility factor of hydrogen-doped natural gas mixtures across a temperature range of -10 degrees C to 110 degrees C and a pressure range of 2 to 12 MPa, with hydrogen blending ratios of 5%, 10%, 20%, 30%, and 40%. The results indicate that the hydrogen blending ratio, temperature, and pressure significantly affect the compressibility factor, particularly under low-temperature and high-pressure conditions, where an increase in the hydrogen blending ratio leads to a notable rise in the compressibility factor. These findings have substantial implications for the practical design of hydrogen-enriched natural gas pipelines, as changes in the compressibility factor directly impact pipeline operational parameters, compressor characteristics, and other system performance aspects. Specifically, the introduction of hydrogen alters the compressibility factor of the transported medium, thereby affecting the pipeline's flowability and compressibility, which are crucial for optimizing and applying the performance of hydrogen-enriched natural gas in transportation channels. The research outcomes provide valuable insights for understanding combustion reactions, adjusting pipeline operational parameters, and compressor performance characteristics, facilitating

关键词： compression factor natural gas pipeline hydrogen blending ratio pipeline operational parameters

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Design strategy for inlet conditions of supercritical CO2 centrifugal compressors

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JOURNAL OF SUPERCRITICAL FLUIDS 2023年 196卷

作者： Cao, Run Deng, Qinghua Li, Zhigang Li, Jun Gao, Tieyu Xi An Jiao Tong Univ Inst Turbomachinery Sch Energy & Power Engn Shaanxi Engn Lab Turbomachinery & Power Equipment Xian 710049 Shaanxi Peoples R China

To improve the aerodynamic performance and suppress the condensation in supercritical CO2 centrifugal compressors, a design strategy is proposed in this paper. The inlet compression factor and density are adopted to study the compressor performance and flow characteristics by solving three-dimensional Reynolds-averaged Navier-Stokes equations with condensable gas. The results indicate that in the range of operating conditions studied, increasing inlet compression factor or density, the condensation area will decrease. However, the pressure ratio will also decrease. By the means of decreasing inlet compression factor and increasing density, the inlet conditions alter from baseline conditions (7.69 MPa, 305.15 K) to optimization conditions (8.40 MPa, 305.54 K). The condensation area decreases by a large margin and the peak efficiency increases from 73.2% to 75.4%, while the pressure ratio remains unchanged. The design strategy provides a new idea for supercritical CO2 compressors to improve the performance and suppress the condensation at impeller inlet.

关键词： Supercritical carbon dioxide Centrifugal compressor Condensation compression factor Aerodynamic performance

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Frei-Chen bases based lossy digital image compression technique

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APPLIED COMPUTING AND INFORMATICS 2024年第1/2期20卷 105-118页

作者： Al-khassaweneh, Mahmood AlShorman, Omar Lewis Univ Dept Comp & Math Sci Romeoville IL 60446 USA Yarmouk Univ Dept Comp Engn Irbid Jordan Najran Univ Fac Engn Dept Elect Engn Najran Saudi Arabia Najran Univ AlShrouk Trading Co Najran Saudi Arabia

In the big data era, image compression is of significant importance in today's world. Importantly, compression of large sized images is required for everyday tasks;including electronic data communications and internet transactions. However, two important measures should be considered for any compression algorithm: the compression factor and the quality of the decompressed image. In this paper, we use Frei-Chen bases technique and the Modified Run Length Encoding (RLE) to compress images. The Frei-Chen bases technique is applied at the first stage in which the average subspace is applied to each 3 x 3 block. Those blocks with the highest energy are replaced by a single value that represents the average value of the pixels in the corresponding block. Even though Frei-Chen bases technique provides lossy compression, it maintains the main characteristics of the image. Additionally, the Frei-Chen bases technique enhances the compression factor, making it advantageous to use. In the second stage, RLE is applied to further increase the compression factor. The goal of using RLE is to enhance the compression factor without adding any distortion to the resultant decompressed image. Integrating RLE with Frei-Chen bases technique, as described in the proposed algorithm, ensures high quality decompressed images and high compression rate. The results of the proposed algorithms are shown to be comparable in quality and performance with other existing methods.

关键词： Big data problem compression factor Frei-Chen basis Run Length Encoding

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Improved Particle Swarm Optimization for Trajectory Planning in a Six-Degree-of-Freedom Robotic Arm 17

Improved Particle Swarm Optimization for Trajectory Planning...

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17th International Conference on Advanced Computer Theory and Engineering

作者： Zhang, Jianzhong Wang, Pengju Anhui Jianzhu Univ Sch Elect & Informat Engn Hefei Peoples R China

ISBN: (纸本)9798331539894;9798331539887

Aiming at the problem of the UR5 robot's unsmooth trajectory during operation, in order to improve the robot's motion accuracy and operation efficiency, this paper proposes a joint space trajectory planning method based on 3-5-3 piecewise polynomial interpolation, which can better meet the speed and acceleration constraints of the robot in different motion stages while ensuring the smoothness of the trajectory, thereby improving the operation stability of the robot. Under the conditions of satisfying the speed and acceleration constraints, the improved particle swarm optimization (PSO) algorithm with the introduction of compression factor and improved adaptive factor is used to optimize the interpolation time of the robot. Compared with the traditional PSO algorithm, the improved PSO algorithm is not easy to fall into the local optimum, making the trajectory planning more efficient. The experimental results show that the improved PSO algorithm not only significantly shortens the operation time of the robot, but also makes the trajectory smoother and the overall operation effect better.

关键词： UR5 PSO trajectory optimization polynomial interpolation compression factor adaptive factor

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Refractive and corneal responses of young myopic children to short-term orthokeratology treatment with different compression factors

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CONTACT LENS & ANTERIOR EYE 2020年第1期43卷 65-72页

作者： Wan, Kin Lau, Jason Ki-kit Cheung, Sin Wan Cho, Pauline Hong Kong Polytech Univ Sch Optometry Ctr Myopia Res Kowloon Hong Kong Peoples R China

Purpose: To evaluate changes in refractive and corneal responses in myopic children wearing orthokeratology (ortho-k) lenses with conventional compression factor (CCF, 0.75 D) and increased compression factor (ICF, 1.75 D). Methods: This was a double-blind self-controlled study. Subjects were randomly fitted with CCF in one eye and ICF in the fellow eye. Weekly monitoring of refraction, visual acuity (VA), external ocular health, and corneal responses were performed over one month of lens wear and after discontinuation of lens wear until stabilization was achieved. Results: Twenty-five subjects, aged 9.4 +/- 1.0 years, completed one-month lens wear, of whom 23 completed the washout period. The first fit success rates for CCF and ICF were 93% and 96%, respectively. Myopia, unaided VA, central corneal thickness, anterior corneal curvatures (K), apical power (AP), and corneal resistance factor (CRF) all changed significantly during the study period (P < 0.003). Between-eye difference was significant only for myopia reduction (P = 0.001). About 4% and 8% of ICF and CCF eyes were under-corrected. The attempted target was achieved in about 80% of CCF and 60% of ICF eyes at week 4. At the end of the washout period (3 weeks), myopia, K, and AP were significantly different compared to baseline (P < 0.001). Conclusion: Increasing the compression factor did not affect the first fit success rate and external ocular health, but did allow faster correction of refractive error within one month of lens wear. Further investigation is warranted to investigate the long-term effects of ICF on myopia control compared to CCF.

关键词： Orthokeratology compression factor Cornea Myopia Refraction

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