The curvature measurement of the human eyeball

The curvature of the cornea in the ophthalmology field is essential data, especially for humans when they are being tested for wearing contact lenses, or for patients undergoing refractive surgery by either knife or laser. It is extremely difficult to measure the curvature of the eye precisely because the measurement of the cornea, using a contact tool, is not possible. In this paper, we propose a method to measure the curvature using lens aberration theory and an image processing technique. We project a circular grating, known as a Placido disc, on to the cornea. The reflective image does not have equal divisions and this distortion value contains the curvature information.     

On filling discs in Borel radius of meromorphic mapping with finite order in the unit circle

Using Ahlfors' covering surface method, some properties on Borel radius of meromorphic functions with finite order in the unit circle are obtained. The main object of this paper is to prove the existence of filling discs in Borel radius of such functions, which briefly extends the results of A. Rauch.     

The stability of the boundary layer on a compliant rotating disc

The boundary layer over a infinite rotating disc is 3D and offinite depth. The breakdown and eventual transition of flowover the surface is preceded by the emergence of crossflow vorticesthat are stationary with respect to the disc. These result froman inviscid instability mechanism associated with an inflexionpoint within the boundary layer's velocity profile or a mechanisminduced by the balance between viscous and Coriolis forces.It has been seen in past studies that compliance can substantiallypostpone the onset of transition, therefore the aim of thisresearch is to investigate whether compliance can be used asa useful tool to do so here. We use numerical and asymptoticmethods to predict possible behaviour by calculating growthrates and producing neutral solutions for the wave number andorientation of both inviscid and viscous modes. The resultsobtained suggest that the inviscid mode of instability willbe stabilized by compliance but the viscous mode will be greatlydestabilized.     

旋转盘腔流场速度与压力的实验研究

本文描述一个旋转盘腔流场的实验研究。该盘腔由一个旋转盘，一个静止盘及静止的外围屏组成．实验表明在盘腔的两个盘面上都有边界层形成，在边界层中，流体除有切向速度外，还有沿径向的二次流存在。在边界层外的核心区中径向速度为零。一般来说，静盘边界层比转盘边界层向紊流转捩地要早。另外，压力的测量表明，在半径较大的区域中压力分布可由“流体以恒角速度旋转”的假设所得的结果近似。     

Differential sacnning calorimetric examination of the human intervertebral disc: establishment of calorimetric standards of different stages of degeneration

Intervertebral disc (IVD) degeneration is a common orthopaedic disorder with significant social and economic impact. The major pathological changes occur in the structure of anulus fibrosus (AF) and nucleus pulposus (NP). According to previous reports differential sacnning calorimetric (DSC) proved to be a suitable method for the demonstration of thermal consequences of local and global conformational changes in the structure of the human intervertebral discs. According to the present study, the DSC results clearly proved that definitive differences are present between the stages of disc degeneration in calorimetric measures. The structural differences between the stages could be also demonstrated by histology.     

Tensor product type subspace splittings and multilevel iterative methods for anisotropic problems

We describe tensor product type techniques to derive robust solvers for anisotropic elliptic model problems on rectangular domains in ^d . Our analysis is based on the theory of additive subspace correction methods and applies to finite element and prewavelet schemes. We present multilevel- and prewavelet-based methods that are robust for anisotropic diffusion operators with additional Helmholtz term. Furthermore, the resulting convergence rates are independent of the discretization level. Beside their theoretical foundation, we also report on the results of various numerical experiments to compare the different methods.     

Improved partial response maximum likelihood method combining modulation code for signal waveform modulation multi-level disc

In this paper, we describe an improved adaptive partial response maximum likelihood （PRML） method combining modulation code tbr signal waveform modulation multi-level disc. This improved adaptive PRML method employs partial response equalizer and adaptive viterbi detector combining modulation code. Compared with the traditional adaptive PRML detector, the improved PRML detector additionally employs illogical sequence detector and corrector. Illogical sequence detector and corrector can aw）id the appearance of illogical sequences effectively, which do not follow the law of modulation code for signal waveform modulation multi-level disc, and obtain the correct sequences. We implement the improved PRML detector using a DSP and an FPGA chip. The experimental results show good performance. The higher efficient and lower complexity can be obtained by using the improved PRML method than by using the previous PRML method. Meanwhile, resource utilization of the improved PRML detector is not changed, but the bit error rate （BER） is reduced by more than 20%.     

Synthesis and characterization of iron‐ and nitrogen‐functionalized graphene catalysts for oxygen reduction reaction

Iron‐ and nitrogen‐functionalized graphene (Fe‐N‐G), as well as iron‐ and nitrogen‐functionalized oxidized graphene (Fe‐N‐Gox) catalysts were synthesized as non‐noble metal electrocatalysts for oxygen reduction reaction (ORR). The physical properties of the resultant catalysts were characterized using nitrogen adsorption measurements, X‐ray diffraction, Raman and X‐ray photoelectron spectroscopies and transmission electron microscopy. Subsequently, ORR activities of the catalysts were determined electrochemically using a conventional three‐electrode cell via cyclic voltammetry with a rotating disc electrode, the results of which indicated that the synthesized catalysts had a marked electrocatalytic activity towards ORR in acid media. Among the synthesized catalysts, that functionalized using 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine as nitrogen source had the highest electrocatalytic activity with the highest onset potential (0.98 V/SHE) and limiting current density (5.12 mA cm⁻²). The findings are particularly important to determine a non‐precious metal catalyst for ORR activity in fuel cells.     

Gromov's Non-Squeezing Theorem and Beltrami Type Equation

We introduce a method for constructing J-complex discs. The method only uses the standard scheme for solving the Beltrami equation and the Schauder principle. As an application, we give a short self-contained proof of Gromov's Non-Squeezing Theorem.     

Near field shock structure of dual co-axial jets

Experimental results on the shock structure of dual co-axial jets are presented. The effects of the geometric parameters of the inner nozzle, jet static pressure ratio (ratio of the exit plane static pressures of the inner and outer nozzles) and the ratio of outer to inner nozzle throat area on the shock structure were studied. A superimposed outer and inner jet structure was observed in the schlieren photographs. The inner flow is compressed by the outer flow resulting in the formation of a Mach disc and an exit shock. A parameter incorporating the effect of Mach number of the inner nozzle and jet static pressure ratio was found to correlate the observations regarding the Mach disc location.