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A Comprehensive Model for Correcting RNFL Readings of Varying Signal Strengths in Cirrus Optical Coherence Tomography
摘要： PURPOSE. To develop a model for the Cirrus HD-OCT that allows for the comparison of retinal nerve fiber layer (RNFL) thickness measurements with dissimilar signal strengths (SS) and accounts for test–retest variability. METHODS. Retinal nerve fiber layers were obtained in normals using the Cirrus optic disc cube 200 3 200 protocol during a single encounter. Five RNFL scans were obtained with a SS of 9 or 10. Diffusion lens filters were used to degrade SS to obtain five scans at each SS group of 7 or 8, 5 or 6, and 3 or 4. The relationship between average RNFL thickness and SS was established, and an equation was developed to allow for adjustment of an RNFL measurement had it been a SS of 7. Intravisit interclass correlation coefficient (ICC) and coefficient of variation (CV) parameter estimates for each SS group were calculated. Repeatability and upper tolerance limit were calculated as 1.96 3 =2 3 within-subject standard deviation (Sw) and 1.645 3 =2 3 Sw, respectively. RESULTS. There was a linear relationship between average RNFL and SS. RNFLadj ? RNFL (cid:2) 1.03*SS t 7.21 allows for the adjustment of RNFL readings to the same SS. Interclass correlation coefficients and CVs were good for all measurements down to SS of 3 or 4. Repeatability and upper tolerance limit were 5.24 and 4.40 lm, respectively. CONCLUSIONS. Our model adjusts RNFL readings based on SS and includes an upper tolerance limit of 5 lm. If validated, this model could improve the detection of real RNFL changes. Further study to validate this model should be performed before widespread use is adopted.
关键词： glaucoma anterior segment,Cirrus OCT,signal strength,optical coherence tomography
更新于2025-09-23 15:22:29
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Influence of phototherapy on adhesive strength and microleakage of bleached enamel bonded to orthodontic brackets: An Invitro study
摘要： Aim: The aim of the present in-vitro study was to explore bleached enamel reversal with phototherapy (Er,Cr:YSGG) when using two dissimilar bonding system to bond brackets on microleakage and shear bond strength. Material and Methods: Amongst one twenty samples, ninety samples were bleached using 35% hydrogen peroxide. After the bleaching procedure, the teeth were randomly divided into three groups according to surface conditioning treatment (n=30 each). Group 1: treated with Er,Cr:YSGG (ECL) Group 2: 10% sodium ascorbate (SA) and Group 3: Bleached only (BO). Based on the type of adhesive, specimens were further classified into eight subgroups. In subgroup 1,2,3 and no treatment (NT) (n=15) adhesive Transbond XT was applied on already etched surface and these subgroups were named as NT-TEP, BO-TEP, ECL-TEP and SA-TEP. Similarly, in subgroup 5,6,7 and NT specimens (n=15) were conditioned with Transbond Plus self-etching primer and these subgroups were named as NT-SEP, BO-SEP, ECL-SEP and SA-SEP. Samples from each subgroup were exposed to increasing load for evaluation of shear bond strength. Microleakage among subgroups were tested by immersing samples in Methylene blue prior one day. Analysis of variance and Tukey multiple comparisons test was used to assess data. Results: The maximum and minimum bond strength was observed in group NT-TEP [17.14(2.54)] and BO-SEP [6.14(0.215)] respectively. Samples conditioned with phototherapy ECL-TEP [16.14(1.231)] exhibited comparable bond strength to specimens conditioned with sodium ascorbate (SA-TEP) [16.72(1.298)]. Similarly, bond strength values of ECL-SEP [13.43(0.921)] and SA-SEP were comparable. The highest microleakage score was demonstrated in BO-SEP [83.21(38.21)] whereas, the lowest microleakage scores were displayed in NT-TEP [23.73(13.45)]. Conclusion: Er,Cr:YSGG phototherapy reversal on bleached enamel with etch and rinse adhesives has a potential to be used in clinical settings alternate to conventional sodium ascorbate when bonding orthodontic brackets.
关键词： Microleakage,Bleached enamel,Sodium Ascorbate,Phototherapy,Bond strength
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Power & Energy Society General Meeting (PESGM) - Portland, OR, USA (2018.8.5-2018.8.10)] 2018 IEEE Power & Energy Society General Meeting (PESGM) - Study of Impact of Cloud Distribution on Multiple Interconnected Solar PV Plants Generation and System Strength
摘要： Dependence of solar power generation on solar irradiance results in sudden and dramatic variations in power generation following significant changes in cloud distribution over a solar PV plant. Currently, this phenomenon is being one of the most challenging issues in resource planning and maintaining the reliability of modern power grids with high penetration of solar power. The dramatic variation of solar power generation has a direct impact on system strength at the Points of Interconnection (POIs). Hence, the power quality of the system is compromised, especially because solar PV plants are usually interconnected to distribution systems and near load zones. In this paper, an Artificial Neural Network (ANN) based approach is developed to forecast the clouds distribution for the estimation of sudden and dramatic variations in the solar irradiance. This estimate is used to evaluate the system strength in terms of voltage stability at each POI. We apply newly developed methodology to measure the system strength known as Site-Dependent Short Circuit Ratio (SDSCR), which provides more accurate results of system strength evaluation. The validity and effectiveness of the developed approach is confirmed through comparing its results versus the cloud distribution data provided by weather satellites.
关键词： Artificial neural network,renewable energy,system strength,voltage stability,short circuit ratio
更新于2025-09-23 15:22:29
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Effects of triethylamine on the imidization temperature and properties of PI adhesive
摘要： To make clear the effects of triethylamine(TEA) on the imidization temperature and properties of polyimide(PI) adhesive,precursors poly(amic acid) salt(PAAS) synthesized via 4,4-Diaminodiphenylmethane(MDA),2,2-Bis[4-(4-aminophenoxy)phenyl]propane(BAPP),3,3',4,4'-Benzophenonetetracrboxylic dianhydride(BTDA) and TEA in N-Methyl pyrrolidone (NMP) were prepared and used to obtain PI adhesive. The chemical structure of PAAS and PI films were confirmed by 1H NMR and FTIR spectroscopy. It was found that PI-2 adhesive obtained from PAAS-2( the mole ratio of TEA/repeating unite of PAA=2/1) had the best property. TGA showed that the temperature for 5% weight loss of PI-2 could achieve 497 ℃ and tensile test showed PI-2 had superior bonding strength of 14.83 MPa. In addition,the damping performance of PI-2 had a great improvement compared with PI obtained from PAA. Moreover,through the study of imidization temperature,the results suggested that PI adhesive obtained from PAAS could complete the imidization reaction at 280 ℃,which had great significance for saving energy. And PI-300 ℃(the maximum imidization temperature of which was 300 ℃) had superior thermal stability,bonding strength and damping performance simultaneously.
关键词： Imidization temperature,Bonding strength,Polyimide,Poly(amic acid) salt
更新于2025-09-23 15:21:21
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Robust flower-like ZnO assembled ?2-PVDF/BT hybrid nanocomposite: Excellent energy harvester
摘要： Need of renewable green energy sources due to low cost synthesis, mechanically strong, high energy storage capacity with improved dielectric performance have been receiving much attention. Present work render the ZnO particle and flower-like morphology assemble semicrystalline β phase PVDF/BT nanocomposite, successfully synthesized by spin coating method and characterized by XRD, SEM, EDS and FTIR techniques. Also the energy storage density of composite with modified structure is largely increased with value 0.056 Jcm-3 at 6 MV/m which is 66% higher than virgin β-PVDF and 82% piezoelectric energy harvesting efficiency. Maximum dielectric constant is 1774 at 1 Hz for PVDF-BaTiO3-ZnOf [P-BT-ZnOf] nanocomposite film and maximum breakdown strength of 43 kVcm-1. Electrochemical study reveals that P-BT-ZnOf nanocomposite film manifest better potential material. In terms of mechanical performance, P-BT-ZnOf nanocomposite shows maximum Young modulus of 204 MPa, tensile strength of 28.7 MPa and 23.1% elongation to break. These results provide promising capability to enhance the performance of composites for energy storage application, transducers, sensors, capacitors etc.
关键词： Energy density,Tensile strength,Dielectric constant,Nanocomposites,Breakdown strength
更新于2025-09-23 15:21:01
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Influence of laser weld shape on mechanical and fatigue behaviour of single lap laser welded joints
摘要： Traditional manufacturing processes, like arc welding and resistance spot welding, are still the main welding processes to join structural components used across the on/o?-road vehicle industry. Due to the abundance of data, experiences and insights over the decades of usage, lot of fatigue design data has been generated for different joint geometries produced using these methods. The laser welding process has excellent capabilities to join thin sheet metal structures with minimum heat input resulting into lower deformation and improved productivity that offers significant benefit as compared to the arc and resistance welding processes. However, due to the agility of designing joint configurations and limited availability of understanding regarding the fatigue behaviour of laser welded joints, the need arises for the fatigue design data. Most of the research presents the use of straight linear shape laser welds and limited knowledge exist regarding the influence of shape of laser welds on mechanical and fatigue performance of the laser welded joints. The laser welded joints produce small notch like radius at the root of laser weld which could act as a stress raiser causing early crack initiation. For this work, C-shape laser weld has been selected as the geometric shape in comparison to the straight linear shape of laser weld produced on a series of single lap joints. Detailed fatigue experimental investigation has been carried out for linear and C-shape laser welded joints tested in 3 different orientations with respect to the applied cyclic load and several different R-ratio’s and the results are compared. The metallurgical studies have been carried out to understand the failure mode and micro-hardness variations across the weld and heat affected zone. Further, the residual stress profiles have been compared for the C-shape laser weld with the linear welds using detailed X - Ray Diffraction based residual stress measurement.
关键词： Laser Weld,Ultra-high strength steel,C Shape,Crack propagation,High strength low alloy steel,Crack initiation
更新于2025-09-23 15:21:01
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Electric field strength-dependent accuracy of TiAlN thin film composition measurements by laser-assisted atom probe tomography
摘要： Accurate quantification of absolute concentrations represents a major challenge for atom probe tomography (APT) since the field evaporation process is affected significantly by the measurement parameters. In the present work we investigate systematically the effect of laser pulse parameters on the accuracy of laser-assisted APT for a TiAlN thin film previously quantified by ion beam analysis, combining Rutherford backscattering spectrometry and time-of-flight elastic recoil detection analysis. The electric field strength is estimated from the Al2+/Al+ charge state ratio for all systematically varied measurement parameters. Subsequently, the absolute concentrations from laser-assisted APT are compared to ion beam analysis data. An increase of the electric field strength from approximately 25–28 V nm?1 improves the accuracy of absolute concentrations measured by laser-assisted APT from 11.4 to 4.1 at% for N, from 8.8 to 3.0 at% for Al and from 2.8 to 0.9 at% for Ti. Our data emphasize that the measurement accuracy of laser-assisted APT for TiAlN is governed by the electric field strength. It is shown that the smallest compositional discrepancies between ion beam analysis and APT are obtained for the maximum electric field strength of approximately 28 V nm?1 at 10 pJ laser pulse energy. This can be rationalized by considering the enhanced ionization of neutral fragments caused by the increased electric field strength.
关键词： accuracy,chemical composition,atom probe tomography,TiAlN,electric field strength
更新于2025-09-23 15:21:01
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Effects of laser scanning strategies on selective laser melting of pure tungsten
摘要： Three types of scanning strategies, including the chessboard scanning strategy, the zigzag scanning strategy and the remelting scanning strategy, were conducted to study the effects of scanning strategies on surface morphology, microstructure, mechanical properties and the grain orientation of selective laser melted pure tungsten. The results showed that the pores and cracks were main defects in SLM-processed tungsten parts. The pores could be eliminated using the remelting scanning strategy. However, the cracks seemed to be inevitable regardless of the applied scanning strategies. The microstructures of SLM-processed tungsten were columnar grains and showed strong epitaxial growth along the building direction. A compressive strength of 923 MPa with an elongation of 7.7% was obtained when the zigzag scanning strategy was applied, which was the highest among the three scanning strategies. By changing the scanning strategies, the texture of SLM-processed tungsten in the direction of processing could be changed.
关键词： microstructure,texture,scanning strategy,compressive strength,pure tungsten,selective laser melting
更新于2025-09-23 15:21:01
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A review on the laser welding of coated 22MnB5 press-hardened steel and its impact on the production of tailor-welded blanks
摘要： The current demand for vehicles with high fuel efficiency, improved safety and enhanced crash-worthiness qualities is being met by making use of high strength components with tailored mechanical properties which are made using tailor-welded blanks. During their production, the surface of the blank needs to be protected against oxidation and decarburisation. Protective coatings are used to protect the steel surface, with Aluminium-Silicon or Zinc-based coatings being the most popular. This work provides a review on the state-of-the-art as well as the issues associated with the laser welding of coated 22MnB5 grade steel to be used in the production of tailor-welded blanks. The paper provides a summary of existing solutions available to overcome these issues while discussing their limitations and the potential for future work.
关键词： Fibre laser welding,tailor-welded blanks,22MnB5,Zn-Coating,press-hardened steel,ultra-high strength steel,Al–Si coating,hotstamped parts
更新于2025-09-23 15:21:01
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Conditions for Quality Dimensions in Direct Laser Melting of Copper
摘要： This paper analyzes the effect of SLM parameters on mechanical characteristics and surface roughness of a single-component copper powder. The study reports on appropriate SLM conditions for a single-component copper powder; to form a layer a technique within layer-by-layer selective laser melting is suggested and comprises roughing, semi-finishing and finishing modes. The work establishes a range to vary surface roughness, porosity and ultimate compressive strength of a single-component copper powder by means of laser processing conditions. Rz is variable 332 to 689 μm, porosity ranges approximately 13-39%, and ultimate compressive strength is 8 to 104 МPа.
关键词： melting conditions,Selective laser melting,roughness,copper,quality,porosity,ultimate compressive strength,coagulation
更新于2025-09-23 15:21:01