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Vitreous anteroposterior traction is an important factor that affects macular hole (MH) formation at the early stage, and vitreous tangential traction can lead to further hole expansion after hole formation. Recent studies have highlighted the significance of Müller cells for the pathogenesis of MH. Since the advent of MH treatment, success rates for MH closure have significantly improved, as has postoperative visual acuity. However, metamorphopsia, an initial and common symptom of MH, still exists. Metamorphopsia is significantly related to the deterioration of visual quality of life and can be used as an independent index to evaluate visual function before and after surgery. In MH patients, metamorphopsia has different manifestations representing different clinical implications. M-CHARTS, as a new means of inspection, can quantify the degrees of metamorphopsia, and with the development of optical coherence tomography (OCT), layer-by-layer scanning of the retinal structure has become possible. These methods enable detailed analysis of the connections between the degree of metamorphopsia and relevant OCT parameters. Preoperative OCT parameters can be used to evaluate the prognosis of the postoperative visual function of MH patients and are therefore of great significance in guiding the treatment of MH patients.

Background: Software is an important windows to offer a variety of complex instrument control and data processing for nuclear magnetic resonance (NMR) spectrometer. NMR software should allow researchers to flexibly implement various functionality according to the requirement of applications. Scripting system can offer an open environment for NMR users to write custom programs with basic libraries. Emerging technologies, especially multivariate statistical analysis and artificial intelligence, have been successfully applied to NMR applications such as metabolomics and biomacromolecules. Scripting system should support more complex NMR libraries, which will enable the emerging technologies to be easily implemented in the scripting environment. Result: Here, a novel NMR scripting system named "NMRPy" is introduced. In the scripting system, both Java based NMR methods and original CPython based libraries are supported. A module was built as a bridge to integrate the runtime environment of Java and CPython. It works as an extension in CPython environment, as well as interacts with Java part by Java Native Interface. Leveraging the bridge, Java based instrument control and data processing methods can be called as a CPython style. Compared with traditional scripting system, NMRPy is easier for NMR researchers to develop complex functionality with fast numerical computation, multivariate statistical analysis, deep learning etc. Non-uniform sampling and protein structure prediction methods based on deep learning can be conveniently integrated into NMRPy. Conclusion: NMRPy offers a user-friendly environment to implement custom functionality leveraging its powerful basic NMR and rich CPython libraries. NMR applications with emerging technologies can be easily integrated. The scripting system is free of charge and can be downloaded by visiting http://www.spinstudioj.net/nmrpy., Comment: 19 pages, 6 figures

A cluster of control moment gyros (CMGs) is widely used as the actuator of attitude control for modern satellite. However, to use CMGs will induce some accessional problems, like the singularity and the failure of them. In this paper, a rotator for the support bracket of each control moment gyro (CMG) is adopted and its application on reconfiguration and singular escape is discussed. The first step puts forward a novel reconfiguration scheme for the CMGs and applied on a satellite, which can adjust the installation angles of the remaining CMGs and make the CMGs remain axial symmetry. Then the characteristic of the output torque is studied in the process of reconfiguration of the CMGs. Based on this characteristic, a special steering law of the CMGs is designed to counteract the disturbance from the reconfiguration. The feasibility of singularity avoidance via the reconfiguration is also discussed by calculating the derivative of the singularity measurement to the installation angle. A singularity avoidance steering law is proposed based on the above calculation.

A new automatic baseline correction method for Nuclear Magnetic Resonance (NMR) spectra is presented. It is based on an improved baseline recognition method and a new iterative baseline modeling method. The presented baseline recognition method takes advantages of three baseline recognition algorithms in order to recognize all signals in spectra. While in the iterative baseline modeling method, besides the well-recognized baseline points in signal-free regions, the 'quasi-baseline points' in the signal-crowded regions are also identified and then utilized to improve robustness by preventing the negative regions. The experimental results on both simulated data and real metabolomics spectra with over-crowded peaks show the efficiency of this automatic method.

Most existing gradient shimming methods for NMR spectrometers estimate field maps that resolve B0 inhomogeneity spatially from dual gradient-echo (GRE) images acquired at different echo times. However, the distortions induced by B0 inhomogeneity that always exists in the GRE images can result in estimated field maps that are distorted in both geometry and intensity, leading to inaccurate shimming. This work proposes a new gradient shimming method based on undistorted field map of B0 inhomogeneity obtained by a more accurate field map estimation technique. Compared to the traditional field map estimation method, this new method exploits both the positive and negative polarities of the frequency encoded gradients to eliminate the distortions caused by B0 inhomogeneity in the field map. Next, the corresponding automatic post-data procedure is introduced to obtain undistorted B0 field map based on knowledge of the invariant characteristics of the B0 inhomogeneity and the variant polarity of the encoded gradient. The experimental results on both simulated and real gradient shimming tests demonstrate the high performance of this new method.

This paper studied the attitude tracking control of a spacecraft using variable speed control moment gyros (VSCMGs) as the actuator. The dynamics of the spacecraft with uncertainties was established. These uncertainties included the moment of spacecraft inertia, the configuration of the VSCMGs, and the moment of the rotator inertia. To solve the problem, the uncertainties were classified into two types. Type I included installation misalignment angles and some part of the rotator inertia, which could impact the character of the output of the VSCMGs. The rest of the uncertainties were categorized as Type II, which could impact the response of the spacecraft attitude control. Different parameter estimation methods were designed for the uncertainties of the two types. For Type-I uncertainties, their relationship with the output-torque error was established based upon which the estimation of Type-I uncertainties was designed. Based on the Lyapunov theory, the estimation of Type-II uncertainties and th...

A robust automatic phase correction method for Nuclear Magnetic Resonance (NMR) spectra is presented. In this work, a new strategy combining 'coarse tuning' with 'fine tuning' is introduced to correct various spectra accurately. In the 'coarse tuning' procedure, a new robust baseline recognition method is proposed for determining the positions of the tail ends of the peaks, and then the preliminary phased spectra are obtained by minimizing the objective function based on the height difference of these tail ends. After the 'coarse tuning', the peaks in the preliminary corrected spectra can be categorized into three classes: positive, negative, and distorted. Based on the classification result, a new custom negative penalty function used in the step of 'fine tuning' is constructed to avoid the negative peak points in the spectra excluded in the negative peaks and distorted peaks. Finally, the fine phased spectra can be obtained by minimizing the custom negative penalty function. This method is proven to be very robust for it is tolerant to low signal-to-noise ratio, large baseline distortion and independent of the starting search points of phasing parameters. The experimental results on both 1D metabonomics spectra with over-crowded peaks and 2D spectra demonstrate the high efficiency of this automatic method. (C) 2013 Elsevier Inc. All rights reserved.

Space-based telescopes always have a deformable segmented primary mirror and a deformable MEMS mirror. Hierarchical control architecture is established for a space-based telescope with multiple wave-front correctors. The hierarchical control architecture organized the whole optical system as five levels, that is, object level, actuator level, local control level, local coordination level and top coordination level. Control strategies and methods are designed for each level controller. The simulation result of correcting wave-front error proves the control architecture and methods feasible.

An improved adaptive backstepping controller design method is proposed for a single input and single output nonlinear system with uncertainty and unknown parameter. The controller expression with undetermined parameters can be acquired by using adaptive backstepping design idea, and the controller parameters are optimized on using the adaptive particle swarm optimization (APSO). The backstepping controller can overcome the plant uncertainties and ensure the robust stability of system. The APSO is used to offset the disturbance and improve the tracking precision. Simulation experimental showed the method effectual.

The layout of the shape actuators in the Primary Mirror segments for a space-based telescope is a crucial factor of the adaptive control system scheme, which determines the correction capability to eliminate the face-shape error caused by the environmental temperature fields and so on. The layout design of the actuators is converted to an optimization problem solved by a Genetic Algorithm. The design result of the Genetic Algorithm is identical with the global search method, which validate the optimization method.

This paper proposed a new intelligent controller for a spin missile with uncertainty and unknown parameter. The spin missile controller expression with undetermined parameters can be acquired by using adaptive backstepping design idea, and the controller parameters are optimized online by using genetic algorithm. By using this new method proposed in this paper, not only the stability of the spin missile control system can be acquired more easily but also the dynamic behavior of the spin missile system is good. The simulation shows that the controller is valid.

This paper investigates the means to design a robust nonlinear controller for a class of nonlinear system with uncertainty and unknown parameter. A new design approach of optimization controller is proposed. The controller expression with undetermined parameters can be acquired by using adaptive backstepping and slide mode design idea, and the controller parameters are optimized on using genetic algorithm. By using controller proposed in this paper, not only the stability of the closed loop system can be acquired more easily but also the dynamic behavior of the system is well. Simulation results show that the controller is valid.

In this paper, a systematical method of designing a high gain and high speed gain-boosted operational transconductance amplifier (gain-boosted OTA) is introduced through mathematically modeling its small signal equivalent circuits in a simple and useful way. By applying root locus techniques to the conclusion of this model, two different ways of optimizing the performance of the gain-boosted OTA are proposed. To verifying the design methods, SMIC 0.18 mum CMOS technology and 1.8 V supply voltage are applied to implement this high gain and high speed OTA. The simulation results show that the output of the sample and hold amplifier (SHA) using these OTAs has minimized ring and overshoot, achieving SNR over 100 dB and SNDR over 70 dB with 39.9 MHZ sinusoid input, and at the higher frequency region, with input signal of 79.9 MHZ, the SNR over 81 dB and SNDR over 63 dB can be achieved.