Numerical and experimental analysis on the helicopter rotor dynamic load controlled by the actively trailing edge flap

Reducing the rotor dynamic load is an important issue to improve the performance and reliability of a helicopter. The control mechanism of the actively controlled flap on the rotor dynamic load is numerically and experimentally investigated by a 3-blade helicopter rotor in this paper. In the aero-elastic numerical approach, the complex motion of the rotor such as the stretching, bending, torsion and pitching of the blade including the deflection of the actively controlled flap (ACF) are all taken into consideration in the structural formulation. The aerodynamic solution adopted the vortex lattice method combining with the free wake model, in which the influence of ACF on the free wake and the aerodynamic load on the blade is taken into account as well. While the experimental method of measuring hub loads and acoustic was accomplished by a rotor rig in a wind tunnel. The result shows that the 3/rev ACF actuation can reduce the $3\omega$ hub load by more than 50\% at maximum, which is significantly better than the 4/rev control. While 4/rev has greater potential to reduce BVI loads than 3/rev with $\mu=0.15$. Further mechanistic analysis shows that by changing the phase difference between the dynamic load on the flap and the rest of the blade, the peak load on the whole blade can be improved, thus achieving effective control of the hub dynamic load, the flap reaches the minimum angle of attack at 90°-100° azimuth under best control condition; when the BVI load is perfectly controlled, the flap reaches the minimum angle of attack at 140° azimuth, and by changing the circulation of the wake, the intensity of blade vortex interaction in the advancing side is improved. Moreover, an interesting finding in the optimal control of noise and vibration is that an overlap point exist on the motion patterns of the flap with different frequencies.

Long-term characteristics of exudative age-related macular degeneration in Japanese patients

Purpose The present study aimed to evaluate the clinical characteristics of exudative age-related macular degeneration (AMD) in Japanese patients over a 10-year period and to compare the past our report. Methods We retrospectively reviewed 1,600 treatment-naïve patients (1,777 eyes) with exudative AMD. The 10 years were divided into 2-year phases I to V. Results Of the 1,600 patients, 720 (45.0%), 733 (45.8%), 98 (6.1%), and 49 (3.1%) were diagnosed with typical AMD, polypoidal choroidal vasculopathy (PCV), retinal angiomatous proliferation, and combined subtypes, respectively. The prevalence of PCV decreased from 54.7% in phase I to 46.0% at phase V. Of the 1,777 eyes, the mean baseline logarithm of the minimum angle of resolution best-corrected visual acuities (BCVAs) in phases I, II, III, IV, and V were 0.70, 0.66, 0.55, 0.50, and 0.48, respectively. Phases III, IV, and V had significantly (P = 0.0012, P<0.0001, P<0.0001, respectively) better baseline VAs compared with phase I. The mean lesion sizes in phases I, II, III, IV, and V were 8.6, 6.7, 5.3, 5.7, and 5.7 Macular Photocoagulation Study disc areas, respectively. The sizes were significantly (P<0.0001 for all comparisons) smaller in phases III, IV, and V compared with phase I. Conclusions Although the prevalence of PCV decreased from 54.7% in phase I to 46.0% at phase V, PCV has nevertheless been highly prevalent in Japanese patients with AMD compared with Caucasian patients. The annual better baseline VAs and smaller lesion sizes over time might be related to development of treatment and better concerns about AMD.

The Effect of Structural Parameters on Response Characteristics of Aeroelastic System in the Presence of Dynamic Stall

The effect of structural paramters on the response and aerodynamic stiffness characteristics of the free aeroelastic system under the influence of dynamic stall is investigated adopting CFD (Computational Fluid Dynamics) method. The equilibrium angle of the spring and the structural stiffness are taken as parameters of interest. Systems with small equilibrium angles enter the symmetric limit-cycle state more quickly after a Hopf bifurcation and experience dynamic stall in both directions, rather than slowly decreasing in minimum angle of attack and remaining in the asymmetric limit-cycle state before dynamic stall in the opposite direction, as is the case with systems with large spring equilibrium angles. Thus, aerodynamic stiffness of system with large equilibrium angles can be more significantly influenced by the change in aerodynamic moment characteristics at the minimum angle of attack. Furthermore, by increasing the initial angular velocity, we find that the system response all becomes symmetric limit cycle and therefore the aerodynamic stiffness appears to have a monotonically increasing characteristic. As to the effect of structural stiffness, it is found that the limit cycle amplitude first increases with structural stiffness after bifurcation, then the amplitude is unchanged with varying structural stiffness at higher Mach number. Energy maps show that the parametric distribution of the energy transfer contributes to this phenomenon. Moreover, when entering the symmetric limit cycle state, the structural stiffness no longer has a significant effect on the aerodynamic stiffness of the system, as the increase in the aerodynamic stiffness is determined solely by the increase in dynamic pressure without the effect of changes in moment characteristics.

Design of vehicle using Ackermann steering with IoT concept

Electric vehicles are becoming more demanding these days. In this project the possibility of using Ackerman steering with electric drive servomotor is explained. Scalability is the advantage of using this mechanism which can be adopted for four-wheel vehicle system as well. The objective of this project is to do design a system using Ackerman steering which determines the maximum and minimum angle of the turning of the wheels. It also avoids the front tire slippage and activates pure rolling. Ackermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii. The geometrical solution to this is for all wheels to have their axles arranged as radii of circles with a common centre point. As the rear wheels are fixed, this centre point must be on a line extended from the rear axle. Intersecting the axes of the front wheels on this line as well requires that the inside front wheel be turned, when steering, through a greater angle than the outside wheel. The microcontroller used in this project is ATMega16 andlmax232 is used for the serial data transmission.

Primary slow-coagulation transscleral cyclophotocoagulation laser treatment for medically recalcitrant neovascular glaucoma

AimsTo report treatment outcomes of slow-coagulation continuous-wave transscleral cyclophotocoagulation (TSCPC) as an initial surgical intervention in patients with neovascular glaucoma (NVG).MethodsA retrospective study including 53 patients (mean age of 69.6±16.6 years and mean follow-up of 12.7±8.9 months) with a diagnosis of NVG and no previous incisional glaucoma or cyclophotocoagulation surgeries. All patients underwent slow-coagulation continuous-wave TSCPC (1250-milliwatt power and 4-second duration).Primary outcome measure was surgical success defined as an intraocular pressure (IOP) from 6 to 21 mm Hg with a reduction ≥20% from baseline, no reoperation for glaucoma and no loss of light perception vision. Secondary outcome measures include IOP, glaucoma medications, visual acuity (VA) and complications.ResultsIOP decreased from 40.7±8.6 mm Hg preoperatively to 18.4±12.2 mm Hg postoperatively (p<0.001). The preoperative number of glaucoma medications dropped from 3.3±1.1 at baseline to 2.0±1.5 at the last postoperative visit (p<0.001). The cumulative probabilities of success at 12 and 24 months were 71.7% and 64.2 %, respectively. Mean logarithm of the minimum angle of resolution VA was relatively unchanged from 2.27±0.63 to 2.25±0.66 at the last follow-up visit (p=0.618). The most common observed complications were decrease in baseline VA (13.2%) and anterior chamber inflammation (9.4%).ConclusionsSlow-coagulation TSCPC is an effective and relatively safe initial surgical intervention in medically uncontrolled NVG.

Age-related changes of color visual acuity in normal eyes

Purpose To evaluate the age-related change in color visual acuity (CVA) in normal eyes. Methods In total, 162 normal eyes (162 subjects, women: 52, men: 110, age range: 15–68 years) with best-corrected visual acuity (BCVA) ≥20/13 were enrolled. Fifteen colors from the New Color Test (chroma 6) were applied to Landolt “C” rings, white point D65 was applied as background, and a luminance of 30 cd/m2 was set for both the rings and the background. These rings were used to measure the chromatic spatial discrimination acuity as the CVA value, while changing the stimulus size. Correlations of the CVA value of each color and age were evaluated. Mean CVA values of all 15 colors (logarithm of the minimum angle of resolution) were compared between age groups in 10-year increments. Results Nine CVA values (red, yellow-red, red-yellow, green, blue-green, green-blue, purple, red-purple, and purple-red) were negatively correlated with age (all p<0.05); the remaining six (yellow, green-yellow, yellow-green, blue, purple-blue, and blue-purple), as well as BCVA were not. The age groups with the best to worst mean CVA values of 15 colors were as follows: 20–29 (mean ± standard deviation, 0.303 ± 0.113), 30–39 (0.324 ± 0.096), 10–19 (0.333 ± 0.022), 50–59 (0.335 ± 0.078), 40–49 (0.339 ± 0.096), and 60–69 (0.379 ± 0.125) years. There were statistically significant differences between mean CVA values of the following groups: 20–29 and 40–49 years; 20–29 and 60–69 years; 30–39 and 60–69 years (all p<0.01). Conclusions The CVA values related to the medium/long-wavelength-sensitive cones were more susceptible to aging than those related to the short-wavelength-sensitive cones. This differed from previous reports, and may be related to the difference in the range of foveal cone function evaluated with each examination.

Effect of minimonovision in bilateral implantation of a novel non-diffractive extended depth-of-focus intraocular lens: Defocus curves, visual outcomes, and quality of life

Purpose To evaluate overall patient satisfaction, spectacle independence, visual acuity, and prevalence of optical phenomena following bilateral implantation of a new non-diffractive extended depth-of-focus intraocular lens targeted for minimonovision. Methods Multicenter prospective case series. Postoperative far and near visual acuity at 3 months and patient quality of life by NEI-VFQ-25 questionnaire were assessed. Postoperative evaluation included defocus curves analysis, spectacle independence assessment, and recording of photic phenomena. Results The study enrolled 97 eyes of 59 patients that underwent femtosecond-assisted cataract surgery with AcrySof IQ Vivity intraocular lens implantation. Thirty subjects (60 eyes) were eligible for analysis. After 3 months, postoperative achieved binocular uncorrected visual acuity was −0.03 ± 0.06 logarithm of the minimum angle of resolution for distance, 0.06 ± 0.06 logarithm of the minimum angle of resolution for intermediate, and 0.19 ± 0.03 logarithm of the minimum angle of resolution for near. Defocus curve showed a smooth profile with no abrupt decrease of visual acuity. Minimonovision significantly improved visual acuity compared to when minimonovision was neutralized, for values of defocus curves from −1 to −3 D ( p < 0.05). Twenty-six (87%) patients reported complete spectacle independence. High levels of satisfaction for distance and near vision resulted at VFQ-25 questionnaire. Only two patients complained of halos (6.7%) and one of them also of glare (3.3%). Conclusions Implantation of this new non-diffractive extended depth-of-focus intraocular lens with minimonovision resulted in satisfying far, intermediate, and near visual acuity with a consistent reduction of spectacle dependence and improvement in patient's quality of life.

Refractive amblyopia among children aged 4–12 years in a hospital-based setting in Gaza Strip, Palestine

Background: Refractive amblyopia is the most common cause of amblyopia in the Gaza Strip. However, the pattern of this condition has not yet been studied in this region. This study aimed to determine the pattern of refractive amblyopia in Gazan children aged 4?12 years.Methods: This was a hospital-based cross-sectional study using a purposive sampling method. Children aged 4?12 years who attended the Children’s Unit at Gaza Ophthalmic Hospital, Gaza Strip, Palestine from September 2019 to July 2020, were examined. A comprehensive eye test was conducted for all participants. Those who failed the eye examinations and were diagnosed with refractive amblyopia were included in the study. Demographic data and amblyopic refractive error patterns were analyzed accordingly.Results: Of the 107 children, 72.9% were newly diagnosed with refractive amblyopia. The mean ± standard deviation (SD) of age of the children who participated was 7.85 ± 1.55 years. Approximately two-thirds of the patients were female (57.9%). Unilateral amblyopia was predominant in 60.7% of the cases. Moderate amblyopia was common (81.9%). A total of 149 amblyopic eyes were examined in total, with a mean ± SD (range) of best-corrected distance visual acuity and spherical equivalent of 0.45 ± 0.19 (0.2 to 1.3) logarithm of the minimum angle of resolution and + 0.76 ± 4.51 diopters (- 10.25 to + 11.50). Astigmatism was the most common amblyogenic factor (53.7%) among children with amblyopia.Conclusions: The frequency of refractive amblyopia was 72.9%, and meridional amblyopia accounted for the highest percentage. Girls were more commonly affected than boys. The majority were in the 7-year-old age group. Most cases were unilateral with moderate refractive amblyopia. Our study yields insights into the patterns of refractive amblyopia among children in the Gaza Strip.

Quantification of Ocular Parameters To Create An Anatomical Eye Model for The Japanese Population

This prospective observational study aimed to evaluate the eye shape and visual function of Japanese people through a multicenter approach and to create a Japanese model eye. Uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively) in the log minimum angle of resolution (logMAR), subjective and objective spherical equivalent values (SE) of ocular refraction, anterior and posterior corneal curvature (ACC and PCC, respectively), anterior and posterior corneal asphericity (ACA and PCA, respectively), central corneal thickness (CCT), anterior chamber depth (ACD), and ocular axial length (AL) were measured in the eyes of 250 participants (mean age = 46.5 ± 18.0 years, range: 20–90 years) across five institutions in Japan. The mean UDVA, CDVA, subjective SE, objective SE, ACC, PCC, ACA, PCA, CCT, ACD, and AL were 0.68, -0.08, -2.42 D, -2.66 D, 7.77 mm, 6.33 mm, -0.31, -0.39, 0.55 mm, 2.92 mm, and 24.78 mm, respectively. Age-related changes and sex-based differences were observed in the visual acuity, refraction, corneal shape, ACD, and AL. Although the sample size needs to be increased, the results of this study can be applied to the development of refractive correction methods and various vision-related fields.