近视眼全阈值静态中心视野改变的研究

１９９７年３月～１９９８年２月，我们采用自动静态视野仪检查了８１例（１５３眼）近视眼患者的视野改变，并分析其损害的特点及规律。１资料与方法１．１一般资料本组年龄８～３８岁，平均２４．４岁。屈光度－０．５０Ｄ～－２８．００Ｄ，其中近视低度１６例（３１眼...

基于混合布谷鸟算法的图像阈值分割

利用布谷鸟算法的高效性,选取基于粒子群算法的布谷鸟算法,结合OTSU法设计适应度函数,求解最佳分割阈值,并与原始算法、全阈值迭代方法进行对比,结果表明,将改进后的布谷鸟算法应用于图像分割中,可提升图像分割效率.

分区域阈值法在软土微结构分析中的应用

利用环境扫描电子显微镜(ESEM)对软土固结土样的微观结构进行观测并获取土样微结构ESEM图片。采用全区域阈值法和分区域阈值法,获取ESEM图片二值化过程中的阈值以提取微结构参数计算结果表明:分区域阈值法获得的微孔隙率等参数较全区域采用单一阈值获得的微孔隙率参数更接近三相图结果,最小相对误差的平均值为4.9%,是一种有效的、理想的土体微结构图片分析方法。

基于混合颜色空间的反应孔图像分割算法研究

为了准确的分割出卡板上面的反应孔从而不影响和对患者病情的诊断,提出了一种基于Lab颜色空间以及HSV颜色空间的反应孔图像分割方法。根据反应孔图像的自身特点,通过在Lab颜色空间运用最大类间差进行阈值分割,在HSV颜色空间运用全局阈值法进行阈值分割,然后将分割得到的两个结果进行区域合并、滤波,最终得到目标区域。结果表明,该算法能够准确的将反应孔图像从卡板上面分割出来,并有效的抑制了噪声及光照不均带来的影响。

Early all-zero blocks detecting method for video coding based on novel threshold

In order to decrease both computational complexity and coding time, an improved algorithm for the early detection of all-zero blocks （AZBs） in H. 264/AVC is proposed. The previous AZBs detection algorithms are reviewed. Three types of transformed frequency-domain coefficients, which are quantized to zeros, are analyzed. Based on the three types of frequencydomain scaling factors, the corresponding spatial coefficients are derived. Then the Schwarz inequality is applied to the derivation of the three thresholds based on spatial coefficients. Another threshold is set on the basis of the probability distribution of zero coefficients in a block. As a result, an adaptive AZBs detection algorithm is proposed based on the minimum of the former three thresholds and the threshold of zero blocks distribution. The simulation results show that, compared with the existing AZBs detection algorithms, the proposed algorithm achieves a 5% higher detection ratio in AZBs and 4% to 10% computation saving with only 0. 1 dB video quality degradation.

Simulation of a Double-Gate Dynamic Threshold Voltage Fully Depleted Silicon-on-Insulator nMOSFET

A novel planar DGDT FDSOI nMOSFET is presented, and the operation mechanism is discussed. The device fabrication processes and characteristics are simulated with Tsuprem 4 and Medici. The back-gate n-well is formed by implantation of phosphorus at a dosage of 3 × 10^13 cm^-2 and an energy of 250keV and connected directly to a front-gate n^＋ polysilicon. This method is completely compatible with the conventional bulk silicon process. Simulation results show that a DGDT FDSOI nMOSFET not only retains the advantages of a conventional FDSOI nMOSFET over a partially depleted （PD） SOI nMOSFET--that is the avoidance of anomalous subthreshold slope and kink effects but also shows a better drivability than a conventional FDSOI nMOSFET.

A Temperature-Dependent Model for Threshold Voltage and Potential Distribution of Fully Depleted SOI MOSFETs

A temperature-dependent model for threshold voltage and potential distribution of fully depleted silicon-on- insulator metal-oxide-semiconductor field-effect transistors is developed. The two-dimensional potential distribution function in the silicon thin film based on an approximate parabolic function has been applied to solve the two-dimensional Poisson＇s equation with suitable boundary conditions. The minimum of the surface potential is used to deduce the threshold voltage model. The model reveals the variations of potential distribution and threshold voltage with temperature, taking into account short-channel effects. Furthermore, the model is verified by the SILVACO ATLAS simulation. The calculations and the simulation agree well.

Projection of the East Asian westerly jet under six global warming targets

This study investigates the projected changes in the East Asian westerly jet(EAJ)under six global warming targets(1.5℃,2.0℃,2.5℃,3.0℃,3.5℃,and 4.0℃)relative to the present climate,using the outputs of CMIP5 models.The results show that the westerly tends to weaken slightly under the 1.5℃warming target.Under the 2.0℃target,it is projected to intensify south of the EAJ’s axis(approximately 40°N)and decay north of the axis.This change becomes increasingly evident under the 2.5℃and higher warming targets,which suggests that the EAJ’s axis will move farther and farther southward,but its intensity will change little with increasing global warming.Further analyses suggest that the change in the EAJ is closely related to the inhomogeneous rising rate of air temperature in the mid–upper troposphere.The relatively slow-rising air temperature in the mid–upper troposphere over the EAJ’s entrance and exit regions will lead to a negative(positive)meridional temperature gradient to the south(north),and will then accelerate(decelerate)the westerly on the EAJ’s south/north side.

Projected changes in the western North Pacific subtropical high under six global warming targets

The summer western North Pacific subtropical high(WNPSH) has large influences on the East Asian summer climate. Many studies have focused on the projected changes in the WNPSH, but little is known about the changes under different global warming targets, such as 1.5℃ and 2.0℃. This study investigates the changes in the WNPSH under six global warming targets(1.5℃, 2.0℃, 2.5℃,3.0℃, 3.5℃, and 4.0℃) in both the mid-and lower troposphere, using the outputs of CMIP5 model in historical simulations and under Representative Concentration Pathway 8.5. The projected changes in the WNPSH, which is measured by multiple variables, show that it changes little under the 1.5℃ target in the mid-troposphere, but weakens and retreats approximately 2.5° in longitude under the 2.0℃ target. It tends to linearly weaken with warming greater than 2.5℃ and shifts eastward by approximately 6.0° in longitude by the 4.0℃ target. Meanwhile, the WNPSH intensifies and extends westward under the 1.5℃ target in the lower troposphere, but changes little with warming rising from 1.5℃ to 2.0℃. It is projected to extend westward by approximately2.0° in longitude by the 4.0℃ target.

Investigation on the threshold control of safety blasting vibration velocity for the extraction of complicated orebody under railway

The threshold control of safety blasting vibration velocity is a significant process for the underground mining of complicated ore deposit under construction,road,and water.According to the equivalent principle of displacement and velocity of mass point,differential evolution is put forward based on 3DEC dynamic analysis,making the calculation more efficient and accurate.The 3DEC model of the complicated orebody under railway is established according to the topographic maps and geological data of the eastern Pyrite Mine.The stimulus-response distribution of internal stress and displacement fields are demonstrated by analyzing the on-site monitoring vibration displacement and velocity data of the mass point.The reliability of parameter selection,such as blasting simulation waveforms,rock damping,is identified.The safety vibration velocity of railway is set to 4.5 cm/s in line with the requirement of safety blasting rules.Thus,the maximum amount of single-stage explosive in this region is 44.978 kg.The simulation result is in good agreement with the on-site monitoring datum.No displacement and settlement of the 701 railway special line was achieved by choosing the critical amount of the single-stage explosive.

Safety threshold of high-speed railway pier settlement based on train-track-bridge dynamic interaction

This paper presents a method to determine the safety threshold of bridge pier settlement in high-speed railways.An analytical expression of the mapping relationship between the pier settlement and the rail deformation is derived theoretically for the double block ballastless track-bridge system.By adopting the superposition of the track random irregularity and the rail deformation caused by the pier settlement as the excitation inputs,the variations of vehicle dynamics indices with pier settlement are comparatively analyzed.Then,the safety threshold of the bridge pier settlement is obtained according to the limit of vehicle running safety and ride comfort indices of the high-speed trains.Results show that the dynamics indices of different trains have different sensitivities to the pier settlement,and the train CRH2C is the most sensitive one among all the types of Chinese high-speed trains.When passing through the bridges in common span with pier settlement at the speed of 250–350 km/h,the trains suffer the low-frequency excitations,and the vertical acceleration of car body is most sensitive to the pier settlement of all the dynamics indices.When the car body vertical acceleration just exceeds the allowable limit,the critical settlement value is 23.4 mm,which is much bigger than the pier differential settlement limit in the current code for Chinese high-speed railways.

Fabricating ultralow-power-excitable lanthanide-doped inorganic nanoparticles with anomalous thermo-enhanced photoluminescence behavior

Trivalent lanthanide(Ln^(3+))-doped luminescent nanoparticles(NPs)have been extensively investigated as deep-tissue-penetration visual bioimaging agents owing to their exceptional upconversion and near-infrared(NIR)luminescence upon irradiation of NIR light.However,in most cases,the power density of irradiation used for in vivo biological imaging is much higher than that of the reported maximum permissible exposure(MPE)value of NIR light,which inevitably does great damage to the living organisms under study and thus impedes the plausible clinical applications.Herein,by using a facile syringe pump-aided shell epitaxial growth method,we construct for the first time a new class of Ln^(3+)-doped KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs that can be activated by utilizing a 980-nm xenon lamp or diode laser with an ultralow excitation power density down to 0.08 mW cm^(−2),a value that is approximately 4 orders of magnitude lower than the MPE value set by the American National Standards Institute(ANSI)for safe bioimaging in vivo.By combining the comparative spectroscopic investigations with atomic-resolved spherical aberration corrected transmission electron microscopy(AC-TEM)characterization,we find that the reduced crystallographic defects are the primary cause underlying such an ultralow-power-excitable feature of the KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs.And,by the same token,the resultant KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs also exhibit an anomalous thermo-enhanced photoluminescence(PL)behavior coupled with an excellent photothermal stability that cannot occur in other Ln^(3+)-doped core-shell NPs.These findings described here unambiguously pave a new way to prepare high-quality Ln^(3+)-doped luminescent NPs with desirable ultralow-power-excitable capability and photothermal stability for future biomedical applications.

Hepatic CT Image Query Based on Threshold-based Classification Scheme with Gabor Features

Hepatic computed tomography(CT) images with Gabor function were analyzed.Then a threshold-based classification scheme was proposed using Gabor features and proceeded with the retrieval of the hepatic CT images.In our experiments, a batch of hepatic CT images containing several types of CT findings was used and compared with the Zhao's image classification scheme, support vector machines(SVM) scheme and threshold-based scheme.

Half thresholding eigenvalue algorithm for semidefinite matrix completion

The semidefinite matrix completion(SMC) problem is to recover a low-rank positive semidefinite matrix from a small subset of its entries. It is well known but NP-hard in general. We first show that under some cases, SMC problem and S1/2relaxation model share a unique solution. Then we prove that the global optimal solutions of S1/2regularization model are fixed points of a symmetric matrix half thresholding operator. We give an iterative scheme for solving S1/2regularization model and state convergence analysis of the iterative sequence.Through the optimal regularization parameter setting together with truncation techniques, we develop an HTE algorithm for S1/2regularization model, and numerical experiments confirm the efficiency and robustness of the proposed algorithm.

Stability analysis for delayed viral infection model with multitarget cells and general incidence rate

In this paper, the sharp threshold properties of a （2n ＋ 1）-dimensional delayed viral infection model are investigated. This model combines with n classes of uninfected tar- get cells, n classes of infected cells and nonlinear incidence rate h（x,v）. Two kinds of distributed time delays are incorporated into the model to describe the time needed for infection of uninfected target cells and virus replication. Under certain conditions, it is shown that the basic reproduction number is a threshold parameter for the existence of the equilibria, uniform persistence, as well as for global stability of the equilibria of the model.