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A Performance Evaluation of a Solar Air Heater Using Different Shaped Ribs Mounted on the Absorber Plate—A Review
摘要： In this paper, the effect of various shapes of ribs used in Solar Air Heaters (SAHs) was discussed. The review is concentrated on the geometry of the rib and its location on the SAH panel. Both numerical and experimental works were considered for discussion with dry air and Nano ?uids as a working ?uid. The in?uence of various shapes, such as an L shape, W shape, V shape, Multiple V shape, V shape with a gap, detachable & attachable ribs etc., was analyzed. The common fact observed from this analysis is that the implementation of arti?cial roughness in the absorber plate results in a considerable increase in the rate of heat transfer. Further, it is observed that ‘Multiple V-shaped with open between the ribs’ results in the maximum thermal enhancement when compared to the other shapes.
关键词： shape of rib,solar air heater,friction factor,heat transfer
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Post-assembly in-situ check of parabolic trough modules by VISshed
摘要： An innovative instrument for the post-assembly in-situ check of parabolic trough modules is here reported. The instrument, named VISshed, is thought for the shed, where the parabolic trough modules are assembled just before their installation in the plant. The instrument is simply composed by one or more cameras installed on a motorized slide and a fake receiver. These components have to be precisely placed over the module; in the paper several indications for the accomplishment of this task are given. The sequence of images captured during the camera(s) translation from one rim of the module to the opposite one are processed according to the VIS method, here described in detail. The most important outputs are contour-map and mean value (for each facet) of the intercept factor. Furthermore, the image processing gives precise information to operators about how to improve the canting, as well as, at the end of optimization, the final shape quality of each facet (panel) installed in the module. This final panel check, after assembly, is a great opportunity for the customer to reject those panels which result too much deviating from the ideal parabola.
关键词： intercept factor,parabolic trough modules,canting,VISshed,shape quality
更新于2025-09-04 15:30:14
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The outcomes of aflibercept therapy in patients with age-related macular degeneration resistant to bevacizumab or ranibizumab
摘要： Purpose: This study was designed to assess the functional and anatomic outcomes of intravitreal a?ibercept injection in patients with wet age-related macular degeneration (AMD) refractory to intravitreal bevacizumab or ranibizumab therapy. Methods: This retrospective study included 43 eyes of 43 patients resistant to treatment with at least 6 injections of bevacizumab or ranibizumab. Persistent intraretinal and subretinal ?uid (IRF and SRF) on optical coherence tomography (OCT), no improvement in best corrected visual acuity (BCVA), and a central macular thickness (CMT) increase of more than 100 mm due to SRF and/or IRF compared to baseline for at least 6 monthly intravitreal bevacizumab or ranibizumab injections were de?ned as resistant to bevacizumab/ranibizumab therapy. BCVA, intraocular pressure (IOP), CMT, maximum retinal thickness (MRT), and maximum pigment epithelial detachment (PED) height (MPEDH) were evaluated before and after a?ibercept injections. Result: After initiating a?ibercept treatment, the mean ?nal BCVA logarithm of the minimum angle of resolution or recognition (logMAR) improved to 0.84 ± 0.59 which was statistically signi?cant compared to baseline (1.14 ± 0.51), (P < 0.001). After a?ibercept injection, statistically signi?cant reduction was noted in mean CMT (402.6 ± 196.7 mm vs 264.2 ± 52.85 mm, P < 0.05), MRT (435.3 ± 195.2 mm vs 282.2 ± 31.8 mm, P < 0.05), and MPEDH (154.2 ± 86.0 mm vs 68.3 ± 70.6 mm, P < 0.05). There was no correlation between the total number of previous injections and the increase of BCVA (r ? (cid:2)0.10, P ? 0.265). The decrease of mean IOP was statistically signi?cant under a?ibercept treatment (P < 0.001). Conclusions: The present study showed the ef?cacy of a?ibercept treatment in eyes with persistent retinal or SRF under bevacizumab or ranibizumab therapy. A signi?cant anatomical and functional improvement was noted.
关键词： A?ibercept,Age related macular degeneration,Bevacizumab,Ranibizumab,Anti-vascular endothelial growth factor
更新于2025-09-04 15:30:14
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Electromagnetic field analysis of Shielded Composite Dielectric Spherical Shell Resonator in Infrared and Visible regions
摘要： In this paper, we have presented an electromagnetic field analysis of shielded composite dielectric spherical shell resonator. The resonator studied in this work is considered for the first time as no study on such resonators is available in the published literature to the best of the author’s information. This shielded composite dielectric spherical shell resonator is composed of two concentric metal spheres with different dielectric material has been made. The whole assembly is shielded by a perfectly conducting concentric spherical metal. The expression for the resonant frequencies and quality factors have been calculated using numerical methods for both the ?nmTEand ?nmTM modes for an infrared and visible regions. It is found that as the outer radius of the shielded composite dielectric spherical shell resonator increases, the quality factor Q of the resonator increases monotonically. It is also found that if we change the radius of the inner dielectric sphere, there is no appreciable change in resonant frequency of the concerned mode is observed. This is due to the small difference in the permittivities of the materials of the inner and the outer dielectric spheres. It has also been observed that an inner concentric superconducting sphere within a dielectric spherical resonator is a more effective controlling parameter of the resonant frequency than the other parameters.
关键词： Shielded composite dielectric spherical shell resonator,resonant frequencies and quality factor,normal modes
更新于2025-09-04 15:30:14
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[IEEE 2018 XIV International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE) - Novosibirsk, Russia (2018.10.2-2018.10.6)] 2018 XIV International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE) - Virtual Instrument for Assessment of Simulated Signal Integrated Harmonics Factors
摘要： The block diagram of the LabVIEW virtual instrument for the assessment of simulated signal integrated harmonics factors is presented. This virtual device version is equipped with the input module for waveform data points import file. The examples of measurement and use of the integrated harmonics factors values of the investigated voltage for estimating the harmonic distortion of the load circuit current are shown.
关键词： method of the differential equations algebraization (ADE),Weighted THD,n-order integrated voltage (current) harmonics factor (IHF),LabVIEW virtual instrument,PSIM
更新于2025-09-04 15:30:14
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Fabrication of high fill-factor aspheric microlens array by dose-modulated lithography and low temperature thermal reflow
摘要： A cost-effective fabrication method for high quality and high fill-factor aspheric microlens arrays (MLAs) is developed. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography system. Digital masks for several bottom layers are replaced from circle to hexagon for the purpose of enhancing the fill-factor of MLAs, then a low temperature thermal reflow process is conducted, after which the average surface roughness of microlens is improved to * 0.427 nm while the pre-modeled profile keeps unchanged. Experimental results show that the fabricated aspheric MLAs have almost 100% fill-factor, high shape accuracy and high surface quality. The presented method may provide a promising approach for rapidly fabricating high quality and high fill-factor aspheric microlens in a simple and low-cost way.
关键词： high fill-factor,dose-modulated lithography,aspheric microlens arrays,surface roughness,low temperature thermal reflow
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - A Spherical Model of the Array Factor for Active Element Pattern Synthesis
摘要： This article presents a method to improve the accuracy of the array factor generally used to synthesize the Active Element Pattern in a uniform linear array. In the literature, the commonly used array factor is obtained by making a far-field approximation. In this article, we consider the active element pattern synthesis using the Z matrix of the array and we show that the larger the inter-element distance or/and the number of elements are, the lower the accuracy of the far-field approximation will be. This leads to a lower accuracy of the active element pattern synthesis. We propose a spherical model for the array factor and we show that when the far-field approximation is no longer accurate enough to be used, this spherical model can lower the Mean Squared Errors between the synthesized and the simulated active element patterns.
关键词： Mean Squared Error,far-field approximation,array factor,active element pattern
更新于2025-09-04 15:30:14
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Imaging With 3-D Aperture Synthesis Radiometers
摘要： The spatial resolution is still a problem in passive microwave remote sensing, especially in low frequency. In recent years, the satellite formation flying has been proposed. Based on this technique, a large array is able to be synthesized in orbit to achieve higher spatial resolution. However, it is a big challenge for the control system to constrain all the satellites in a coplane in orbit. The 3-D array configuration is a good choice for a synthesized array based on satellite formation flying. In this paper, the complete formulation of visibility functions, including system imperfections, in a 3-D aperture synthesis radiometer (3-D ASR) is derived. The array factor of a 3-D ASR is defined. The reconstructed modified brightness temperature (BT) is a 3-D linear convolution of the modified BT and the array factor. Based on this relationship, the reconstruction method for a practical 3-D ASR is studied. The numerical results demonstrate that the reconstruction method is correct and stable. Finally, a discussion is given to analyze several existing methods that were proposed to reconstruct BT image for 3-D arrays in radio astronomy and earth observation. Compared with these existing methods, our imaging method is more suitable for earth observation based on the technique of satellites formation flying in low earth orbit. In addition, according to the derivations, some mature techniques that were developed for 2-D ASRs may be applied to 3-D ASRs.
关键词： visibility functions,image reconstruction,array factor,3-D aperture synthesis radiometers (3-D ASRs),modified brightness temperature (BT)
更新于2025-09-04 15:30:14
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Frequency-Modulated Wave Dielectrophoresis of Vesicles And Cells: Periodic U-Turns at the Crossover Frequency
摘要： We have formulated the dielectrophoretic force exerted on micro/nanoparticles upon the application of frequency-modulated (FM) electric fields. By adjusting the frequency range of an FM wave to cover the crossover frequency fX in the real part of the Clausius-Mossotti factor, our theory predicts the reversal of the dielectrophoretic force each time the instantaneous frequency periodically traverses fX. In fact, we observed periodic U-turns of vesicles, leukemia cells, and red blood cells that undergo FM wave dielectrophoresis (FM-DEP). It is also suggested by our theory that the video tracking of the U-turns due to FM-DEP is available for the agile and accurate measurement of fX. The FM-DEP method requires a short duration, less than 30 s, while applying the FM wave to observe several U-turns, and the agility in measuring fX is of much use for not only salty cell suspensions but also nanoparticles because the electric-field-induced solvent flow is suppressed as much as possible. The accuracy of fX has been verified using two types of experiment. First, we measured the attractive force exerted on a single vesicle experiencing alternating-current dielectrophoresis (AC-DEP) at various frequencies of sinusoidal electric fields. The frequency dependence of the dielectrophoretic force yields fX as a characteristic frequency at which the force vanishes. Comparing the AC-DEP result of fX with that obtained from the FM-DEP method, both results of fX were found to coincide with each other. Second, we investigated the conductivity dependencies of fX for three kinds of cell by changing the surrounding electrolytes. From the experimental results, we evaluated simultaneously both of the cytoplasmic conductivities and the membrane capacitances using an elaborate theory on the single-shell model of biological cells. While the cytoplasmic conductivities, similar for these cells, were slightly lower than the range of previous reports, the membrane capacitances obtained were in good agreement with those previously reported in the literature.
关键词： Cell,Frequency-modulated wave,Crossover frequency,The Clausius-Mossotti factor,Spectroscopy,Dielectrophoresis,Vesicle
更新于2025-09-04 15:30:14
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Recurrent rates and risk factors associated with recurrent painful bullous keratopathy after primary phototherapeutic keratectomy
摘要： Objective: To assess the recurrent rate, mean survival time, and risk factors associated with recurrent painful bullous keratopathy (BK) after primary treatment with phototherapeutic keratectomy. Methods: Medical records from 72 patients (72 eyes) who had phototherapeutic keratectomy for painful BK were evaluated. Data for sex, age, duration of BK, associated ocular and systemic diseases (hypertension, diabetes mellitus, ischemic heart disease, asthma, dyslipidemia, and rheumatoid arthritis), frequency and degree of pain (grade 1–3), visual acuity, corneal thickness, intraocular pressure, and laser setting were extracted and analyzed. Results: The mean age of the patients was 64.2±11.4 years. The mean preoperative duration of BK was 15.0±11.0 months. Most patients had pseudophakic BK (69.40%). Majority of the cases had grade 3 degree of pain (48.60%). Glaucoma and hypertension were markedly found among these patients (51.40% and 19.40%, respectively). Preoperative mean intraocular pressure and corneal thickness were 13.70±4.95 mmHg and 734.1±83.80 μm, respectively. The mean laser diameter and depth were 8.36±1.22 mm and 38.89±8.81 μm, respectively. Systemic disease was significantly associated with the risk for developing recurrent painful BK (P=0.022, hazard ratio [HR] 1.673, 95% confidence interval [CI] 1.08–2.58). The overall recurrent rate was 51%. The average duration time of recurrent painful BK was 17.3±12.9 months (range 1–50 months). The median survival time before recurrence was 29.0±6.6 months. Conclusion: Systemic disease was found to be the only risk factor significantly associated with the development of recurrent painful BK. Low recurrent rate and long mean survival time showed that phototherapeutic keratectomy was effective in relieving recurrent painful BK and can be used as an alternative procedure for patients waiting for corneal transplantation.
关键词： mean survival time,phototherapeutic keratectomy,PTK,recurrent painful,bullous keratopathy,risk factor
更新于2025-09-04 15:30:14