Fungal corneal ulcer after repair of an overhanging filtering bleb:A case report

BACKGROUND Overhanging filtering bleb is a common complication after trabeculectomy and surgical repair is an effective treatment when the patient presents with apparent symptoms.Filtering bleb relevant infection including in the filtering bleb itself and even endophthalmitis in some severe cases has been reported.However,corneal fungal infection after filtering bleb repair is rarely reported.CASE SUMMARY A 57-year-old Chinese man who had sensations of redness and foreign body sensations in the left eye 3 wk after repair of overhanging filtering bleb.3 wk ago,due to sensations of a foreign body in the left eye for 3 years with worsening for 3 mo.The patient was diagnosed as overhanging filtering bleb and underwent a repair of overhanging filtering bleb.Postoperative,the filtering bleb formed well and the intraocular pressure is normal.But the patient gradually develop redness,pain and a grey infiltrate of the cornea in the eye.Finally it developed into fungal corneal ulcer.Through asking the medical history,we found the patient had irregularly self-medicated for years with glucocorticoid eye drops for years to relieve the foreign body sensation in the eye caused by filtering bleb overhanging.Because the glucocorticoid eye drops he used years ago had provide normal sensation to the eye.After 3 mo of anti-fungal treatment,the inflammation was controlled.CONCLUSION In addition to avoiding the development of overhanging filtering bleb after trabeculectomy,the present case report also suggests that clinicians should pay more attention to the patient’s ocular self-medication history.Particularly in patients with a history of glaucoma or eye surgery.Because these patients may be exposed to more types of eye drops than other individuals,they may select the wrong medi-cations for long-term use,based on their previous experience.

Effect of Ship Bow Overhang on Water Shipping for Ship Advancing in Regular Head Waves

This paper presents the results of an experimental investigation dealing with the effect of bow overhang extensions on the quantity of shipping water over the foredeck in case of ships advancing in regular head waves. To perform this investigation, a series of free-running tests was conducted in regular waves using an experimental model of a multipurpose cargo ship to quantify the amount of shipping water. The tests were performed on five bow overhang variants with several combinations of wavelength and ship speed conditions. It was observed that the quantity of shipping water was affected by some parameters such as wavelength, ship speed, and bow shape in terms of an overhang extension. The results show the significant influence of an overhang extension, which is associated with the bow flare shape, on the occurrence of water shipping. These results involve the combined incoming regular waves and model speed.

Overhanging glaucoma filtration bleb related to cataract surgery

A 74-year-old man presented with a three-year history of foreign body sensation in the right eye after cataract surgery.He underwent uneventful trabeculectomy with mitomycin C(MMC) in the right eye seven years ago.Slit-lamp examination revealed a large avascular filtration bleb overhanging on the cornea with a thin base connected to the conjunctiva.Preoperative ultrasound biomicroscopy(UBM) impressions were confirmed by leakage of aqueous from the incision intraoperatively.Surgical dissection and revision of the bleb was performed with satisfactory outcome.Histopathologic evaluation showed proliferation of fibrous tissue under the conjunctival epithelia with irregular cystoids change.The current case may be the first report of a post-trabeculectomy overhanging filtration bleb related to cataract surgery.The possible mechanism may be related to microleakage of the surgical wound after phacoemulsification which initiated the healing and scarring process.

大悬伸状态加工水室封头重型铣削振动分析

针对大悬伸状态下加工水室封头产生的重型铣削振动,以重型铣削水室封头现场加工实验为基础,分析重型铣削振动产生的原因,并根据现场实验对工件已加工表面形貌进行对比分析。建立重型铣削刀具偏心跳动模型、刀具与主轴系统的轻微变形模型和进给系统刚度的模型,分析其对重型铣削瞬时切削厚度的影响,同时建立重型铣削力数学模型和铣削轨迹模型。分析重型铣削系统振动影响因素及规律,振动模型预测结果与实验结果吻合较好。该工作为进一步研究重型铣削振动特性提供依据。

进口悬臂式轧机轧辊轴密封的改进

本文介绍了一种用于悬臂式轧机轧辊轴头的多唇密封，它具有刚度大、密封效果好、使用寿命长和温度补偿性等特点。

宽系桶柱滚动轴承开发研究

针对高速线材厂悬臂式轧机四列短圆柱滚子轴承的轴承座无法实现自位前提下，提出研制宽系桶柱滚动轴承，以更替原四列短圆柱滚子轴承，解决轴承异常偏载短寿及烧胶问题。

Analysis on the Formation Reason of A Rare Big Hailstone Weather in Nantong City

By using the ground and high-altitude observation data,NCEP 6 h reanalysis data and CINRAD/SA radar observation data,the circulation situation,the atmospheric stability degree and the radar echo characteristics of a strong convection weather which occurred in Nantong area of Jiangsu Province on June 14 in 2009 were analyzed.The results showed that the hailstone happened in the large scale background of coastal trough rear which was established by the northeast low vortex.The warm air in the middle-low layer was covered with the cold air in 500 hPa,which provided the favorable condition for the occurrence of strong convection weather which included the hailstone,the thunderstorm,the strong wind and so on.Seen from the analysis on the radar echo,the windstorm which induced this strong convective weather had the characteristics of super monomer windstorm.In the northwest and the southeast,there were 2 obvious outflow boundaries and the overhanging structure characteristics.The strong vertical shear and the suitable frozen layer height in the middle-low layer of troposphere were also favorable to fall the hailstone.

A New Finite Element Model with Manufactured Error for Additive Manufacturing

Additive manufacturing(AM),adding materials layer by layer,can be used to produce objects of almost any shape or geometry.However,AM techniques cannot accurately build parts with large overhangs,especially for the large features close to horizontal,hanging over the void.The overhangs will make the manufactured model deviate from the design model,which will result in the performance of the manufactured model that cannot satisfy the design requirements.In this paper,we will propose a new finite element(FE)analysis model that includes the manufacturing errors by mimicking the AM layer by layer construction process.In such FE model,an overhang coefficient is introduced to each FE,which is defined by the support elements in the lower layer.By mimicking the AM process from the bottom layer to the top layer,all the FE properties are updated based on their overhang coefficients,which makes the computational model be able to predict the manufactured model with manufacturing errors.The proposed model can be used to predict the performance of the AM objects in the design stage,which will help the designers to improve their design by the simulation results.

TC21钛合金封闭深槽腔大悬伸快进给铣削加工技术

从材料和结构介绍TC21钛合金封闭深槽腔类零件的加工特点。为了实现TC21钛合金结构件高性能加工,基于生产实践,从刀具选型、刀具轨迹、冷却方法、切削参数、刀具寿命等方面,研究大悬伸快进给刀具在TC21钛合金封闭深槽腔类零件上的高效切削运用,总结了一套完整的大悬伸快进给铣削方案。试验证明,悬伸比9倍径的快进给刀具能高效切削TC21钛合金深槽腔。对比强力铣削和插铣,快进给铣削提效明显。

微细铣削过程中刀尖径向总跳动度的实验研究

微细铣削过程中,刀尖径向总跳动度与每齿进给量在同一量级,其影响切削过程切削厚度,从而影响切削过程切削力。文章基于轴向铣微孔实验分析了微细铣削过程中主轴转速和刀具悬伸量对刀尖径向总跳动度的影响规律,采用线性回归最小二乘估计法建立刀尖径向总跳动度预测模型,并对预测模型进行显著性检验和拟合度检验,检验结果表明:预测模型可用于切削参数范围内刀尖径向总跳动量的预测。

基于切削稳定性与表面质量约束的铣削工艺参数优化研究

铣削工艺系统的动态特性随着刀具夹持长度改变而变化,影响关联的铣削稳定性与加工表面质量,进而导致铣削加工的工艺规划具有不确定性。针对此问题,本文综合刀具悬伸量与传统铣削用量作为输入,分别建立极限切削深度与表面粗糙度的反向传播神经网络模型(BPNN),并进一步以其表达铣削稳定性与加工质量约束,构建以刀具悬伸量和粗/精加工阶段铣削用量为优化变量,以粗/精铣总加工时间为目标的铣削工艺参数优化模型,采用麻雀搜索算法(SSA)对模型进行寻优求解。以某型数控机床的夹具型腔铣削加工为例,采用刀具悬伸量与各阶段铣削用量的优化配置进行加工实验,总切削时间12.577 min与表面粗糙度值3.01μm验证了优化模型的可行性和有效性。

基于静动态力学分析的微细铣刀几何参数优化

在微细铣削过程中,刀具悬伸量、刃口长径比等参数的选择至关重要,适宜的刀具结构参数能有效提高刀具刚度及整体强度,降低刀具折断的概率。针对直径为0.1mm的双刃微细立铣刀展开研究,基于Ansys有限元仿真软件,对具有不同刃口形状、悬伸量、刃口长径比结构的微细铣刀进行应力及模态分析,探讨各参数对微细铣刀刚度的影响,分析刀具折断的主要因素。研究表明:刀具刃口形状以及刃口长径比对微细铣刀模态不造成影响,刀具悬伸量是影响模态的主要因素,在实际加工过程中,应控制刀具悬伸量在15mm^20mm区间内,刃口长径比小于4;针对微细铣刀刀头根部与刀颈的连接处施加圆角进行优化设计,有效改善了应力集中现象。文章的研究成果可以为微细铣削刀具结构优化设计提供理论依据。

Optimal design of FRMSM to decrease detent force

An optimal configuration of the flux-reversal linear synchronous motor (FRLSM) with the optimal number of attachment permanent magnets (PMs) was presented. The optimal model of 2 000 N was designed to reduce the detent force by redesigning the air-gap structure and skewing. The design parameters,mover PMs and stator core,were selected for optimal design by DOE. The thrust and the detent force of the designed optimal models were compared by finite element analysis (FEA). As a result,the thrust of the optimal model is slightly decreased by 1.97% compared with the basic model,and the detent force of the optimal model is greatly decreased by 88.47% compared with the basic model.

TC21钛合金转轴梁双闭角深槽腔高效铣削技术研究

针对TC21钛合金转轴梁双闭角深槽腔类零件铣削效率低的问题,从材料和结构分析出发,基于生产实践,从零点系统、夹具设计、零件工艺凸台设计、刀具方案、切削参数、换刀方式等方面,研究TC21钛合金转轴梁深槽腔及双闭角区域的高效切削技术,总结了一套完整的结合零点定位和大悬伸快进给铣削的方案。对比原方案,加工周期缩短50%以上。

Assessment of the Quality of Composite Resin Restorations

Purpose: To evaluate the quality of the composite restorations. Material and Methods: A total of 246 composite restorations in 125 patients attending the Conservative Dentistry Clinics at the Faculty of Dentistry, University of Khartoum were examined. Both anterior and posterior composite restorations were included. California Dental Association Quality Evaluation System was used for the evaluation. Results: Fifty two percent of all restorations were found to be satisfactory, while the remaining 48% were not satisfactory. With regard to surface and colour criteria, colour mismatch within the range (34.8%) and slight surface roughness (26.6%) were the most common defects. The most frequent defects of the anatomical form were restoration overhang (26.8%). The majority of the restorations above 4 years old were of unacceptable anatomical form (66.7%), and their marginal integrity was less acceptable than more recent restorations (46.7%). Conclusions: Forty eight percent of the examined composite restorations needed to be replaced, and the unacceptable anatomic form was the main cause of failure of composite restorations.

Formation and Evolution of Surface Morphology in Overhang Structure of IN718 Superalloy Fabricated by Laser Powder Bed Fusion

Controlling the overhang surface quality is still a formidable challenge in manufacturing the components with complex structures during laser powder bed fusion(LPBF).This study systematically uncovers the effects of the volume energy density(VED)and overhang angle on the evolution of surface morphology and corresponding surface roughness(Ra)of top and down-skin surfaces of IN718 superalloy samples.The results show that balling,Plateau-Rayleigh instability,open pore and humping caused by the material stacking are the main factors contributing to the apparent deterioration of top surface quality.When the VED is 80–100 J/mm^(3),the high down-skin surface roughness is attributed to the serious dross caused by recoil pressure and sinking of the melt pool.Using insufficient VED(15–50 J/mm^(3))can easily lead to poor metallurgical bonding and material spalling on the down-skin surface.In addition,overhang angle also significantly affects down-skin surface roughness due to the stair effect and the adhered unmelted powders.An improvement in the surface quality of down-skin surface is observed when the overhang angle increases.Based on the finding of this investigation,an optical VED(59.5 J/mm^(3))significantly improves the top and down-skin surface quality and porosity of overhang samples.This study provides an insight into synergy ascension of the top and down-skin surface quality in the overhang structure.

Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers

To study the nonlinear dynamic behavior of the bladed overhang rotor system with squeeze film damper (SFD), a blade-overhang rotor-SFD model is formulated using the lumped mass method and the Lagrange approach. The cavitated short bearing model is employed to describe the nonlinear oil force of the SFD. To reduce the scale of the nonlinear coupling system, a set of orthogonal transformations is employed to decouple the one nodal diameter equations of blades, which are coupled with the dy- namical equations of the rotor, with other equations of blades. In this way, the original system with 16+4n (n≥3) degrees of freedom (DoF) is reduced to a system with 24 DoF only. Then the parametric excitation terms in the blade-overhang rotor-SFD model are simplified in terms of periodic transforma- tions. The coupling equations are numerically solved and the solutions are used to analyze the dy- namic behavior of the system in terms of the bifurcation diagram, whirl orbit, Poincaré map and spec- trum plot. A variety of motion types are found such as multi-periodic, quasi-periodic, and chaotic mo- tions. Moreover, the typical nonlinear dynamic evolutions including the periodic-doubling bifurcation and reverse bifurcation are noted. It is noticed that there exist apparent differences in the dynamic behavior between the blade-overhang rotor-SFD models without and with considering the effect of blades.

Structural topology optimization subject to overhang angle constraint with overhang length relaxation in additive manufacturing

This paper studies additive manufacturing(AM) oriented structural topology optimization(TO).The minimum compliance design subject to overhang angle constraint with overhang length relaxation and horizontal minimum length control is considered.Although the overhang length relaxation allows additional flexibility for AM product design,there have been very limited studies on it.This paper elucidates that the overhang angle constraint we proposed can identify the lower boundary element that violates the overhang angle constraint.Taking advantage of this fact,we achieve the overhang length relaxation by specifying that the volume fraction of the elements that violate the overhang angle constraint in each local area of the design domain is less than a specified upper bound.A formula for estimating the maximum allowable overhang length of this method is proposed and verified.The horizontal minimum length constraint is also employed in this paper.While controlling the horizontal length size of the structural member,this constraint together with the overhang angle constraint with overhang length relaxation suppresses the hanging feature.The gradient-based optimization algorithm method of moving asymptotic(MMA) is used to solve the TO formulation.Numerical examples show the effectiveness of this method.It is observed that the new constraint alleviates the main issues of traditional overhang angle constraints,i.e.,gray element issue,stress concentration issue,and shattered structure issue.Compared with the strict traditional overhang angle constraint,the new formulation reduces structural compliance.

Growth and Cycles in China's Unbalanced Development: Resource Misallocation, Debt Overha ng, Economic Inequality, and the Importance of Structural Reforms

The recent China's growth slowdown is both cyclical and secular, driven by external and internal factors. In this article, I highlight several key internal factors that have hindered China's growth in recent years. These include worsening misallocation of resources and declining growth of total factor productivity, plus rising household income inequality and debt overhang in the face of tightened liquidity constraint. All of these show the urgency for deepening reforms in China's key macroeconomic landscapes in order to remove institutional barriers and distortions deep-rooted in the nation's economic and financial structure, and to correct fundamental imperfections of its socialeconomic system. 1 argue that such refonns are of critical importance for China's pursuit of healthy and sustainable growth and of balanced and adequate development going forward.