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Fracture strength of silicon torsional mirror resonators fully coated with submicrometer-thick PECVD DLC film
摘要： In this work, we attempted to enhance the torsional fracture strength of single crystal silicon (SCS) resonators for micro mirrors application by introducing a 300 nm-thick diamond-like carbon (DLC) coating. The SCS torsional beams of the resonators were 20 μm wide and 9 μm thick, and fully coated with DLC films using plasma enhanced chemical vapor deposition (PECVD) at three different deposition bias voltages. The resonators were driven by a piezoelectric actuator and their angular amplitude was measured by a custom-made torsional test system. Average nominal torsional fracture strength of DLC coated resonators was 11.1–30.0% higher than that of bare SCS, reaching a value of 2.93 GPa. The torsional fracture strength of resonators exhibited a good agreement with the tensile fracture strength. Deviations in torsional strength were reduced with increasing deposition bias voltage due to the compressive residual stress of DLC films.
关键词： Single crystal silicon,Micro mirror resonator,Diamond-like carbon film,Strength deviation,Torsional fracture strength
更新于2025-09-23 15:23:52
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Comparison of Clinical Outcomes between Torsional and Longitudinal Phacoemulsification
摘要： Purpose: To compare the clinical outcomes during phacoemulsification when using recently improved longitudinal (Stellaris?, Bausch & Lomb, Rochester, NY, USA) and torsional (Infiniti Ozil?, Alcon, Fort Worth, TX, USA) ultrasound. Methods: The present study included 74 eyes of 59 patients undergoing cataract surgery. Operated eyes with mild cataract (nuclear sclerosis grade 1 and 2), moderate cataract (nuclear sclerosis grade 3) and hard cataract (nuclear sclerosis grade 4 and 5) were compared in terms of the total phacoemulsification (phaco) time, average phaco power, total phaco energy and amount of fluid used during cataract surgery between the 2 modalities. Endothelial cell density, corneal edema, central corneal thickness (CCT), surgically induced astigmatism (SIA) and best-corrected visual acuity (BCVA) were also evaluated preoperatively and up to 3 month postoperatively. Results: In mild cataracts, the operative parameters and corneal changes were similar between the 2 modalities. In moderate cataracts, the total phaco time was significantly higher in the torsional group than the longitudinal group, but the average phaco power, total phaco energy, and amount of fluid were not significantly different. In patients with hard cataract, the torsional group showed higher total phaco time (27.50 ± 17.77 sec vs. 97.08 ± 12.67 sec), average phaco power, total phaco energy, persistent corneal edema at 1 week postoperatively and more endothelial cell loss at 3 month postoperatively (16.33 ± 15.50% vs. 38.71 ± 26.49%). Postoperative CCT, SIA and BCVA were not significantly different in hard cataracts between the 2 modalities. Conclusions: In mild and moderate cataracts, the efficiency of phaco and corneal changes were similar between the 2 modalities. However, recently improved longitudinal phaco showed superior efficiency for hard cataracts and induced less endothelial cell loss than torsional phaco.
关键词： Longitudinal,Cataract surgery,Phacoemulsification,Nuclear density,Torsional
更新于2025-09-23 15:22:29
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Side chain torsion dictates planarity and ionizability of Green fluorescent protein’s chromophore leading to spectral perturbations.
摘要： Spectral characteristics of Fluorescent Proteins (FP) are well studied and through protein engineering, several FP variants constituting entire visible spectrum have been created. One of the most common mechanisms attributed to spectral shifts in FP are excited state proton transfer (ESPT), hydroxyl moiety protonation and deprotonation, along with chromophore Cis-Trans isomerism. Most widely studied FPs are those derived from avGFP (Aequorea victoria GFP) and Dsred (Discosoma coral). Apart from the above mechanism, certain interacting residues are said to play a vital role in altering the proton transfer pathway shift. The torsional changes of wild avGFP, S65T avGFP, and Dsred has been studied to van der Waals packing in Dsred is more compact than that of avGFP, thus creating a low solvent occupiable environment and reduced solvent interactions having higher red spectral hypothesize the torsional landscape and altered residual interactions are prominent factors for the spectral shifts. Through our 200 ns molecular dynamics investigation we prospect that leading to numerous spectral variants. Similarly, the hydrogen-bonded networks solely cannot dictate the energy landscape of FPs. Non-bonded interactions also can create secondary harmonic shifts by dipole-dipole inductions. Side chain contacts tend to alter the topological and torsional geometry, thereby disturbing the chromophore’s planarity. Side chain torsional variations have almost been unaccounted for their distortions in FP’s. We comprehend the inter-residual contact distance and the geometrical descriptors.
关键词： Green fluorescent protein,spectral perturbations,Sidechain torsional variations,Residual accessible area,Chromophore planarity
更新于2025-09-23 15:21:01
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Ultra-Short-Term Photovoltaic Power Prediction Based on Self-Attention Mechanism and Multi-Task Learning
摘要： This paper deals with methods for parameter estimation of two-mass mechanical systems in electric drives. Estimates of mechanical parameters are needed in the start-up of a drive for automatic tuning of model-based speed and position controllers. A discrete-time output error (OE) model is applied to parameter estimation. The resulting pulse-transfer function is transformed into a continuous-time transfer function, and parameters of the two-mass system model are analytically solved from the coefficients of this transfer function. An open-loop identification setup and two closed-speed-loop identification setups (direct and indirect) are designed and experimentally compared. The experiments are carried out at nonzero speed to reduce the effect of nonlinear friction phenomena on the parameter estimates. According to results, all three identification setups are applicable for the parameter estimation of two-mass mechanical systems.
关键词： resonant mechanical load,Electric drives,parameter estimation,torsional oscillation
更新于2025-09-23 15:19:57
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Improving the effects of laser hardening of steels by applying a longitudinally torsional ultrasonic field
摘要： The paper is devoted to the expediency of using ultrasonic treatment in combination with laser hardening for U8, U10, X12M steels and the study of the effect of ultrasonic longitudinal and torsional acoustic vibrations on the intensification of an increase in the concentration of point defects in the crystal structure. The introduction of a longitudinal and torsional ultrasonic field by transforming longitudinal ultrasonic vibrations made it possible to form a highly concentrated effect, which led to an increase in the effects of laser hardening.
关键词： ultrasonic treatment,crystal structure,steels,laser hardening,longitudinal and torsional acoustic vibrations
更新于2025-09-16 10:30:52
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Nonlinear torsional buckling and postbuckling analysis of cylindrical silicon nanoshells incorporating surface free energy effects
摘要： In the present study, a size-dependent shell model is developed which can afford to describe the nonlinear torsional buckling and postbuckling characteristics of cylindrical nanoshells in the presence of surface stress effects. To accomplish this purpose, the Gurtin–Murdoch theory of elasticity together with the von Karman geometric nonlinearity is implemented into the ?rst-order shear deformation shell theory. A linear variation through the thickness is considered for the normal stress component of the bulk to satisfy the balance conditions on the free surfaces of the nanoshell. By means of the virtual work principle, the non-classical governing differential equations are constructed in which the transverse displacement and Airy stress function are considered as independent variables. Thereafter, a boundary layer theory is employed including the effect of surface stress in conjunction with the nonlinear prebuckling deformations and the large postbuckling de?ections. Subsequently, an ef?cient solution methodology based on an improved perturbation technique is put to use to obtain the size-dependent critical torsional buckling loads and the associated postbuckling equilibrium paths. It is observed that the torsional load exhibits a signi?cant increase after reaching the minimum postbuckling load. Also, it is revealed that the effect of surface stress becomes negligible at high values of the de?ection.
关键词： First-order shear deformation shell theory,Nonlinear torsional buckling,Postbuckling analysis,Surface free energy effects,Cylindrical silicon nanoshells,Gurtin–Murdoch theory,von Karman geometric nonlinearity
更新于2025-09-10 09:29:36
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Torsionally induced exciton localization and decoherence in <i>π</i> -conjugated polymers
摘要： We develop a model of excitons coupled to the rotational motion of monomers to study the torsionally induced relaxation and decoherence of excitons in π-conjugated polymers. The model assumes that the monomer units are described by elastically uncoupled harmonic oscillators and that there is a linear exciton-roton coupling. Although the rotational degrees of freedom are much slower than the exciton, so that the adiabatic approximation is generally expected to be valid, we also investigate possible quantized roton corrections via coupled time evolving block decimation-Ehrenfest equations of motion. For the relaxation of the lowest-excited exciton, we find that (1) for a polymer chain with a ground state spiral torsional conformation, the equilibrium angular displacement of each monomer is proportional to the difference of the exciton bond-orders on the neighboring bridging bonds. Consequently, this displacement vanishes in the long chain limit and a classical (Landau) exciton-polaron is not formed. (2) For a polymer chain with a ground state staggered torsional conformation, the equilibrium angular displacement of each monomer is proportional to the sum of the exciton bond-orders on the neighboring bridging bonds. Consequently, there is significant angular displacement and local planarization causing exciton density localization. A classical (Landau) exciton-polaron is formed where the staggered angular displacement is proportional to the exciton density. (3) Generally, in the adiabatic limit, the decay of off-diagonal long-range order (i.e., exciton decoherence) mirrors the localization of the exciton density. However, quantum corrections to the rotational motion alter this adiabatic prediction because of correlated exciton-roton dynamics within the first rotational half-period. In particular, exciton-polaron quasiparticle formation causes more rapid and oscillatory exciton decoherence and slower exciton density localization.
关键词： π-conjugated polymers,exciton,decoherence,torsional relaxation,Landau exciton-polaron
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)] - 3rd generation rim drive heliostat with monolithic sandwich panel
摘要： The improvements of the mechanical structure of the current rim drive heliostat generation with chain drive system and monolithic sandwich structure is described. The improvements of the mechanical structure result in increased torsional stiffness of the pylon, reduced manufacturing effort, increased life time of the chain gears, and better access to the drives. Dynamic wind loads were determined by loading a transient finite element model with pressure distribution time series gained by wind tunnel tests. Due to the rims, the heliostat shows significantly better dynamic behavior than conventional heliostats without rims.
关键词： monolithic sandwich panel,rim drive heliostat,dynamic wind loads,chain drive system,torsional stiffness
更新于2025-09-04 15:30:14