Endoscopy-guided in vivo evaluation of ciliary sulcus location in children with ectopia lentis

Objective To assess a new method to measure the distance of the needle passage from the ciliary sulcus to the corneal limbus anterior border (CTC) in eyes with ectopia lentis directly in vivo via endoscopy and to further evaluate the correlations among the CTC, age, automated horizontal white-to-white distance (WTW), and ocular axial length (AL). Methods The WTW and AL were measured using an optical biometer. An intraocular endoscope was used during transscleral suture fixation of posterior chamber intraocular lenses to identify the true location of the ciliary sulcus. Linear regression analysis was used to assess the correlation between the CTC and other ocular biological parameters, including age, WTW, and AL. Results Thirty eyes of 30 children with ectopia lentis were evaluated. A statistically significant correlation was found between age and the CTC. The CTC could be predicted by the equation CTC = 0.1313 × Age + 0.9666. No statistically significant correlations were found between CTC and WTW, CTC and AL, WTW and AL, or WTW and age. Conclusion Endoscopy is useful for precisely suturing intraocular lens haptics in the real ciliary sulcus. Age can be used as an equivalent parameter for prediction of the true ciliary sulcus location.

An RHT-Model-Based Equivalent Parameter Scheme for Blast Response Simulation of RC Frames

In this paper, a novel equivalent parameter scheme based on the Riedel–Hiermaier–Thoma (RHT) model is proposed for blast response simulations of reinforced concrete (RC) frames. Considering the strengthening effect of longitudinal and stirrup reinforcements on concretes, constitutive parameters in the RHT model are modified to homogenize RC components based on reasonable simplifications and numerical tests. Numerical results of RC beams illustrate that this scheme significantly improves the computational efficiency and effectively predicts real explosion response behaviors with high accuracy. The scheme is then employed for the blast simulation of an RC frame with multiple components with results compared with those of real frame experiments to further demonstrate its reliability. Owing to its efficiency and accuracy, the present RHT-model-based equivalent parameter scheme can serve as a feasible tool to conduct blast response analysis of the RC frame and guide the corresponding anti-explosion designs.

The study of ultrasonic layer-matched to penetrate bone

Acoustic metamaterial layer-matched was designed to enhance ultrasound penetration through bones. The conventional ultrasound layer-matched, known as coupling agent, can only enhance the transmittance of ultrasound to soft biological media, such as cartilage and muscle, but cannot penetrate hard media, i.e. bone. An ultrasound layer-matched based on the impedance matching principle is presented to make ultrasound penetrate bone, which parameters are designed by acoustic metamaterial equivalent parameter technique. The ultrasound layer-matched is fabricated by 3D printing which can correct the aberrations of the bone. Some configurations are investigated by numerical simulation as well as experiments in the anechoic chamber. In particular, a bone matching layer can be designed optimally for the definite thickness of the bone and the definite operating frequency of the ultrasound probe, which enhanced ultrasound to penetrate both of the layer-matched and the bone with no echo. The results of experiments and simulations show that the proposed ultrasound layer-matched metamaterial can enhance the transmission efficiency of ultrasound to penetrate some hard biological media bones.

Research on Trimming Frequency-Increasing Technology for Quartz Crystal Resonator Using Laser Etching

A quartz crystal resonator (QCR) is an indispensable electronic component in the field of the modern electronics industry. By designing and depositing electrodes of different shapes and thicknesses on a quartz wafer with a certain fundamental frequency, the desired target frequency can be obtained. Affected by factors such as the deposition equipment, mask, wafer size and placement position, it is difficult to accurately obtain the target frequency at a given time, especially for mass-produced QCRs. In this work, a laser with a wavelength of 532 nm was used to thin the electrodes of a QCR with a fundamental frequency of 10 MHz. The electrode surface was etched through a preset processing pattern to form a processing method of local thinning of the electrode surface. At the same time, the effect of laser etching on silicon dioxide and resonator performance was analyzed. Satisfactory trimming frequency-increasing results were achieved, such as a frequency modulation accuracy of 1 ppm, frequency distribution with good consistency and equivalent parameters with small changes, by the laser partial etching of the resonator electrode. However, when the surface electrode was etched into using through-holes, the attenuation amplitude of the equivalent parameter became larger, especially in terms of the quality factor (Q), which decreased from 63 K to 1 K, and some resonators which had a serious frequency drift of >40%. In this case, a certain number of QCRs were no longer excited to vibrate, which was due to the disappearance of the piezoelectric effect caused by the local thermal phase change in the quartz wafer.

Coupling Effects of Yaw Damper and Wheel-Rail Contact on Ride Quality of Railway Vehicle

The ride quality of the railway vehicle is not only affected by the wheel-rail contact geometry but also by the yaw damper. In order to explore this variation law, an equivalent parameter model of the yaw damper was established based on the internal characteristics of the yaw damper, which is both accurate and efficient. Then, considering the influence of wheel wear and wheel-rail contact geometry, ride quality of the railway vehicle under different parameters of yaw damper and wheel-rail contact parameters was analysed. The results show that the wheel-rail contact points are scattered on the wheel profile after the wheel wears out, and the equivalent conicity also tends to increase with the increasing operating mileage. The distribution of ride quality space is sensitive to the change of equivalent conicity. In the low equivalent conicity area, the expansion rate of excellent ride quality space is faster. In the high equivalent conicity area, the expansion rate of qualified ride quality space is faster. Appropriate additional stiffness which is oil stiffness in parallel with structural damping in the equivalent parameter model of the yaw damper can improve the vehicle ride quality. The lateral ride quality is influenced obviously with the condition of the damping of the yaw damper being less than 440 kN·s·m−1. Properly reducing the joint stiffness of the yaw damper could reduce the influence of characteristic parameters of the yaw damper and equivalent conicity of the wheel-rail contact on vehicle lateral ride quality. The optimized characteristic parameters of the yaw damper are used in the actual vehicle test, and the ride quality is effectively improved.

The equivalent parameter conditions for constructing multiple integral half-discrete Hilbert-type inequalities with a class of nonhomogeneous kernels and their applications

In this paper, we establish equivalent parameter conditions for the validity of multiple integral half-discrete Hilbert-type inequalities with the nonhomogeneous kernel G ( n λ 1 ∥ x ∥ m , ρ λ 2 ) G\left({n}^{{\lambda }_{1}}\parallel x{\parallel }_{m,\rho }^{{\lambda }_{2}}\hspace{-0.16em}) ( λ 1 λ 2 > 0 {\lambda }_{1}{\lambda }_{2}\gt 0 ) and obtain best constant factors of the inequalities in specific cases. In addition, we also discuss their applications in operator theory.

Thévenin Equivalent Parameter Adaptive Robust Estimation Considering the Erroneous Measurements of PMU

Parameter estimation based on the measurement data of the phasor measurement unit (PMU) is an important approach for identifying the Thévenin equivalent parameters (TEPs) of power systems. However, in the process of acquiring or transmitting data in PMU, measurement errors due to external interference or internal system faults will affect the accuracy of parameter estimation. In this paper, a TEP estimation algorithm based on local PMU measurement is proposed. The algorithm considers the errors of the PMU and introduces Huber function and projection statistics (PS) to eliminate the effects of outliers and leverage measurements, respectively. Additionally, a variable forgetting factor (VFF) is used to quickly eliminate the historical data with measurement deviation and track the changes of the system. The regularization technique is used to solve the divergence problem in the inverse process of the ill-conditioned matrix, thereby improving the stability and generalization performance of the algorithm. Finally, by minimizing the cost function of this algorithm, a recursive formula for the equivalent parameter estimation is derived. The effectiveness of the algorithm is verified on the IEEE 118-bus and IEEE 30-bus systems, and compared with recursive least squares (RLS) and Huber’s M-Estimation; the mean relative errors decreased by 94.75% and 84.77%, respectively.

Equivalent Parameter Conditions for the Validity of Half-Discrete Hilbert-Type Multiple Integral Inequality with Generalized Homogeneous Kernel

Let Gu,v be a homogeneous nonnegative function of order λ,Kn,xm,ρ=Gnλ1,xm,ρλ2. By using the weight coefficient method, the equivalent parameter conditions and best constant factors for the validity of the following half-discrete Hilbert-type multiple integral inequality ∫ℝ+m ∑n=1∞ Kn,xm,ρanfxdx≤Ma~p,αfq,β are discussed. Finally, its applications in operator theory are discussed.