Late corneal ectasia after penetrating and deep anterior lamellar keratoplasty for keratoconus

AIM:To investigate tomographic features of late corneal ectasia after keratoplasty for keratoconus and compare penetrating keratoplasty(PK)and deep anterior lamellar keratoplasty(DALK)in terms of incidence,time of onset and risk factors of corneal ectasia.METHODS:Sixty eyes with PK and 30 eyes with DALK operated between 1999 and 2021 were analyzed.Final Pentacam scans were evaluated together with vision and previous topographies.Main outcome measures were vision,K values,apparent thinning on graft-host cornea and the difference between opposing quadrants in the thinnest point measurements.Anterior segment optic coherence tomography was performed for further evaluation.RESULTS:Mean follow-up was 127.2mo(24–282mo)in PK,and 64.3mo(24–144mo)in DALK.K max was higher in DALK(60.6 vs 56.7 D,P=0.012).Inferior recipient was thinner(595.9μm)in PK than DALK(662.2μm,P=0.021),due to longer follow-up.Overall corneal ectasia rate was 20.0% within 24y.Ectasia rate was the same(6.7%)in DALK 2/30 and in PK 4/60 in 10y and 13.3%in 12y(4/30 and 8/60,respectively).It increased to 23.3%(14/60)in PK over 24y.While ectasia was not seen before 7y in PK,it could be seen in DALK starting from the 5^(th) year.The intervals between keratoplasty and ectasia were 144.5mo in PK and 99mo in DALK.Inferior recipient was significantly thinner in 18 eyes with ectasia(502.7μm)compared to 76 non-ectasia(649.1μm,P=0.000).Inferior graft was thinner(561.0 vs 620.4μm,P=0.006),K max(63.3 vs 56.5 D,P=0.000),and anterior elevation was higher in ectasia(89.1 vs 48.6μm,P=0.002).Accelerated crosslinking was performed on 5 eyes.CONCLUSION:Inferior-superior recipient and inferior graft thinning on tomography,with high K max and anterior elevation emerge as the most reliable criteria for the diagnosis of late ectasia.The incidence of corneal ectasia increases with the time.

Interpretation and characterization of rate of penetration intelligent prediction model

Accurate prediction of the rate of penetration(ROP)is significant for drilling optimization.While the intelligent ROP prediction model based on fully connected neural networks(FNN)outperforms traditional ROP equations and machine learning algorithms,its lack of interpretability undermines its credibility.This study proposes a novel interpretation and characterization method for the FNN ROP prediction model using the Rectified Linear Unit(ReLU)activation function.By leveraging the derivative of the ReLU function,the FNN function calculation process is transformed into vector operations.The FNN model is linearly characterized through further simplification,enabling its interpretation and analysis.The proposed method is applied in ROP prediction scenarios using drilling data from three vertical wells in the Tarim Oilfield.The results demonstrate that the FNN ROP prediction model with ReLU as the activation function performs exceptionally well.The relative activation frequency curve of hidden layer neurons aids in analyzing the overfitting of the FNN ROP model and determining drilling data similarity.In the well sections with similar drilling data,averaging the weight parameters enables linear characterization of the FNN ROP prediction model,leading to the establishment of a corresponding linear representation equation.Furthermore,the quantitative analysis of each feature's influence on ROP facilitates the proposal of drilling parameter optimization schemes for the current well section.The established linear characterization equation exhibits high precision,strong stability,and adaptability through the application and validation across multiple well sections.

Comparison of visual and topographic outcomes of deep-anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus

AIM：To compare visual,surgical and topographic outcomes of deep anterior lamellar keratoplasty（DALK）and penetrating keratoplasty（PK）for keratoconus（KC）.METHODS：In this multicenter,prospective,randomized clinical trial 76 eyes of 71 KC patients operated between January 2011 and July 2014 in 2 tertiary referral hospitals were included. Consecutive patients were alternately selected to receive one of the two surgical methods. Thirty eight eyes underwent DALK with the big-bubble technique and 38 eyes underwent PK.RESULTS：Mean best spectacle corrected visual acuity（BSCVA）at the first postoperative week（P=0.012）and the first postoperative month（P〈0.001）was statistically significantly higher in DALK group. The mean BSCVA at12 mo was not significantly different for DALK（0.30±1.99 log MAR）versus PK（0.40±0.33 log MAR）（P=0.104）. The76.3% of the eyes had a BSCVA over 0.5 in DALK and 47.4%in PK group（P=0.009）. The 7.9% of the eyes had a BSCVA of 1.0 in DALK and 5.3% in PK group（P=0.644）. Mean spherical equivalent was-2.94 D in DALK and-3.09 D in PK group.Mean topographic astigmatism was 4.62 D and 4.18 D respectively. Regular topographic patterns were observed in 31（81.6%）of DALK and 29（76.3%）of PK（P=0.574）. The most frequent topographic pattern was oblate asymmetric bow tie,seen in 39.5% in DALK and 23.7% in PK. CONCLUSION：Big bubble DALK provides an earlier visual improvement compare to PK. However,visual and topographic outcomes are similar to those in PK at 1y. Postoperative complications including rejection and intraocular pressure elevation are more frequent in PK. DALK is a safer alternative to PK for KC. However,intraoperativeperforation of the Descemet＇s membrane is a significant complication.

Critical power of keyhole formation in CW Nd:YAG laser deep penetration welding

The energy model was founded to calculate the critical power of keyhole formation by using the limit principle in CW （ continuous wave ） Nd： YAG laser deep penetration welding process. The model was validated by experiments. The results show that ＇.there are two errors between the calculated critical power of keyhole formation and that of experiments ： one is that the calculated results is less than those of experiments, which is caused by not considering the energy loss by heat conduction in the model of keyhole formation. The other is that there is 0. 9 mm error between the axis of the calculated curve of critical power with location of laser focus and that of experimental curve, which is induced by the excursion of laser focus in laser deep penetration welding. At last, the two errors were revised according to the analyses of the errors.

Numerical simulation of temperature field in deep penetration laser welding of 5A06 aluminum cylinder

Deep penetration laser welding temperature field of 5A06 aluminum alloy canister structure was simulated using the surface-body combination heat source model by ANSYS, which was made up of Gauss surface heat source model and Gauss revolved body heat source model. Convection, radiation and conduction were all con,sidereal during the simulation process. The thermal cycle curves of the points both on the shell outer surface and in the seam thickness direction were calculated. Simulated results agreed well with the experiment results. It concluded that the surface-body combination heat source model was fit for the temperature field simulation of deep penetration laser welding of the aluminum alloy canister structure. This method was proved to be an efficient way to predict the shape and dimension of welded joint for deep penetration laser welding of the aluminum alloy canister structure.

IOP-lowering effects for the application of human umbilical vein in non-penetrating deep sclerostomy in rabbits

AIM: To estimate the effects of human umbilical vein (HUV) implanted under the sclera of glaucoma model on intraocular pressure (IOP) lowering and to investigate its related mechanisms METHODS: A total of 20 human umbilical veins (HUV) were collected from healthy fetus umbilical core. After the establishment of glaucoma model in rabbits, human freeze-dried umbilical vein was implanted under the sclera during NPDS, while for control group, sclerostomy was performed without implant. The formation of the filtration bleb and TOP were detected every 24 hours before surgery and on day 3, 7, 10 and 14 after surgery. Handheld pen-type Tono-pen II tonometer was used to measure TOP after topical anesthesia treatment. Each measurement has three duplicates. The incision recovery, filtration, conjunctiva congestion and anterior chamber inflammation were observed everyday after surgery. RESULTS: IOP was decreased dramatically with less inflammation than traditional sclerostomies with the application of HUV. The significant differences of IOP between the NPDS with and without HUV implant groups were shown up from 10 days after surgery. The average TOP in NPDS without HUV implant was 14.25mmHg, while for NPDS with HUV implant group, it was 12.30mmHg. This structure of filtration bleb, which allowed the aqueous humor to leave the eye, was formed for any type of surgery. However, 1-2 weeks later, filtration bleb was still Existed in the group of sclerostomy with HUV implant and more stable than that of the surgery without HUV implant. Histological observations were performed on day 3, 7 and 14 after surgery. For the eyes under sclerostomy with HUV implant, HUV lumina was shown up on 3 days after surgery with few fibroblast cells near the sclera. On 7 days after surgery, HUV lumina was stably maintained but with obvious fibroblast cells and inflammatory cell. On 14 days after surgery, HUV lumina was still clearly observed but with scarring formation, which suggests that the IOP lowering effects might result from an effective drainage structure formation. CONCLUSION: HUV might be an alternative material to make the drainage pathway for non-penetrating deep sclerostomy.

Fault Zone Fluid Deep-penetrating Techniques for Potash Deposit Prediction in Lanping-Simao Basin,Yunnan,South China

In China,the strategic resource potash is suffering from severe shortages,and the ancient marine solid potash locating is still a problem of long impregnability.Till now,only the Mengyejing Potash Deposit was found

POINT PENETRATION AND DEEP PUNCTURE THERAPIES FOR SCIATICA:AN OBSERVATION ON 108 CASES

In 198 patients with sciatica, 108 cases were randomly chosen as treatment group with point penetration and deep puncture therapies by elongated needle and a group of 9O cases was received filiform needle therapy as control group. In the control group, the way of purgation by twirling the needle was used. The results showed that the total effective rate of the treatment group was 93. 52 %,while in the control group, it was 68. 89 %, X2 = 20. 46, P< 0. 01. It proved that point penetration and deep puncture therapies had better analgesic effect than that of the filifom needle.

Relation between welding parameter and acoustic emission information during laser deep penetration welding

In laser non penetration deep penetration welding process, welding material will vaporize, metal vapor and ambient gas will produce a higher degree ionization, which forms plasma of high concentration. In the case of forming a small hole, plasma will eject from the hole, and form acoustic emission (AE) signals. Because AE information has many advantages such as non contact measuring, fast response, and high ratio of signal to noise, it can be used as a monitor variable for in process control. By studying AE information, information of welding pool and small hole can be obtained. According to characteristic of AE information, this paper reveals the correlation between welding parameters and AE signals, and provides a good base for further quality control.

Donor cornea quality used for penetrating keratoplasty vs deep anterior lamellar keratoplasty

Deep anterior lamellar keratoplasty(DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty(PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on donor endothelium and requires less rigid criteria for donor corneal tissue quality. Therefore, DALK makes it possible to use donor corneas deemed unsuitable for PK. Furthermore, lamellar keratoplasty allows acellular corneal tissue to be transplanted. As a result, long-term preservation techniques are being revisited to increase the availability of donor corneas and subsequently alleviate constraints of availability, cost, storage, and transportation in many countries. The recent alterations in corneal transplantation techniques and hence the type of donor cornea tissues used for each technique, may require corneal surgeons and eye banks to reevaluate their selection criteria. The purpose of this systematic review is to present an updated analysis on the type and quality of donor corneas used for PK and DALK, assess the influence of donor and eye bank factors on the quality of donor corneas, and determine whether any of these donor factors affect clinical outcomes, complications, and graft survivals.

降低井底岩石抗钻能力的钻速提高方法研究及钻头设计

为解决深部地层岩石硬度大、研磨性强、地应力高及可钻性差导致的钻头破岩效率低、钻井速度慢的问题,在分析现有提速技术的基础上,提出了释放地层应力、降低井底岩石抗钻能力的钻井提速新思路,基于该思路设计了井底应力诱导卸荷钻头、聚能攻击卸荷井底应力钻头、差压式钻头、中心差压式钻头、诱导卸荷与磨料射流联合作用钻头、阶梯式钻头和自激轴冲与诱导卸荷耦合破岩钻头等7种新式钻头。通过室内试验、现场试验,验证了其中2种钻头的提速效果:中心差压式钻头在室内试验中提速30.01%,现场试验最高提速318.11%;诱导卸荷与磨料射流联合作用钻头在室内试验中钻进石灰岩和红砂岩时分别提速59.0%和336.0%。该方法的提出及钻头的研制,为解决深部难钻地层的提速问题提供了新途径。

改进YOLOv5的探地雷达常见地下管线识别

针对当前探地雷达(Ground Penetrating Radar,GPR)图像识别准确率低,且小目标识别困难等问题,本文将YOLOv5(You Only Look Once)和ConvNeXt网络相结合,提出一种适用于GPR图像的常见地下管线识别网络ConvNeXt-YOLOv5,显著提高了雷达图像中小目标的识别精度.同时,为了解决因地下管线原始信息不足而导致的模型训练精度低的问题,使用实测GPR图像、时域有限差分法(Finite-Difference Time-Domain,FDTD)与混类增强算法Mixup模拟图像构建数据集.然后,在此数据集上验证了本文所提方法对常见地下管线的识别效果,并用识别后的二维GPR B-scan图像还原出地下管线的三维图像.实验结果表明,对镀锌输水钢管、PVC管、电缆线和含水塑料瓶等常见地下管线进行识别时,ConvNeXt-YOLOv5表现出优良的识别性能.尤其是对PVC管的识别精度提升明显.与YOLOv4、YOLOv5、YOLOv7和Faster R-CNN模型相比,其平均精度均值分别提高了3.83%、2.82%、1.9%和3.72%.同时,三维探地雷达图像更直观的还原了地下管线信息.

深穿透跨尺度辐射场分析软件NECP-MCX研发及应用

西安交通大学核工程计算物理实验室自主研发了深穿透跨尺度辐射场分析软件NECP-MCX。针对大空间伽马射线辐射输运模拟、聚变堆停堆剂量模拟和点源屏蔽问题等新应用场景下的新问题与新挑战,在NECP-MCX中研发了对应的新方法与新功能。针对km尺度的伽马射线辐射输运问题,提出一致性共轭驱动重要性抽样(CADIS)-下次事件估计器(NEE)耦合方法,该方法能够精确高效地获得km尺度距离处的光子通量密度,计算效率比传统的NEE高6.8倍;针对聚变堆停堆剂量问题,采用粒子输运-燃耗-活化-源项耦合分析方法,获得PF线圈、TF线圈、真空室和偏滤器处停堆剂量随停堆时间的变化;对于点源屏蔽问题,提出首次碰撞源(FCS)-CADIS方法,解决CADIS方法对点源进行源偏倚的局限性,FCS-CADIS方法的计算效率比CADIS方法高2倍。

大庆油田萨中开发区二、三类油层同步挖潜补压结合射孔方法

大庆油田萨中开发区二类油层和三类油层平面、纵向交互分布,目前尚未形成同步开发方法。从射孔角度出发,通过分析油层特点,匹配射孔工艺方法,二类油层匹配深穿透(穿深为956 mm)射孔、三类油层匹配超深穿透(穿深为1 308 mm)射孔,建立单井“组合射孔”模式;针对大段三类油层,通过抽稀射孔数,提高单卡层段数,提高过孔压力,建立“组合射孔+限流法压裂”模式。数值模拟和现场分析结果表明:该方法在萨中开发区2个二、三类油层同步挖潜区块应用,“组合射孔”实施20口井,采出端单井含水率多降低2.0%、日产油量增加1.2 t;“组合射孔配套限流法压裂”实施6口井,实现了单孔排量0.6 m3/min以上,平均单井产液量增幅17.56%,含水率多降低0.94百分点。研究成果可有效指导投产设计,对二、三类油层的同步挖潜和提质增效具有重要意义。

大熔深K-PAW熔池及电弧视觉行为特征分析研究

穿孔等离子弧焊接(K-PAW)以其独特的优势,在中厚板的焊接制造中应用广泛,并逐渐向更大厚度的方向发展。然而,随工件厚度增加熔池穿孔出现不稳定等问题,制约了其在实际生产中的应用。分析了14 mm厚304不锈钢在“受控恒定穿孔”控制策略下的大熔深K-PAW熔池特征尺寸变化规律和焊接过程中的熔池行为。通过视觉检测与电信号同步采集系统,对大熔深K-PAW过程中熔池的形貌特征进行定量分析,探究在受控脉冲条件下的熔池特征参数变化情况,以及熔池特征与电信号的同步动态行为规律。以初始电流270 A进行焊接,在起弧的前14 s的盲孔阶段,随着电弧热量积累,熔池不稳定,尺寸出现震荡,最大震荡幅度超过10 mm,同时熔池长宽比也在1.0~1.6范围内变化;随着穿孔于第15 s发生,熔池达到平衡,且长宽比在19 s时达到峰值;维孔阶段,熔池保持稳定,形状未发生大变化。综上,可以通过熔池形状变化趋势来区分焊接阶段。比较了不同焊接电流(280 A、275 A、270 A)的盲孔阶段,发现采用较大的初始电流有利于缩短盲孔时间,由270 A时的22.9 s减小到了280 A时的19.8 s,并降低焊接气孔出现的可能性。最后,发现电弧中心与熔池前边缘的距离可以反映穿孔状态。结果验证了“受控恒定穿孔”控制策略的可行性,并验证了通过视觉特征判断焊接阶段及是否穿孔的可行性。

深水半潜式生产平台电缆密封贯穿装置的设计研究

深水半潜式生产平台电缆密封贯穿装置的设计至关重要,相比以往的常规钻采平台、上部模块等设计要求更高。本文通过深水半潜式生产平台“深海一号”的建造设计经验,对深水半潜式生产平台电缆密封贯穿装置的设计有关注意事项进行总结,对指导深水半潜式生产平台电缆密封贯穿装置的设计有重要参考意义。

基于探地雷达的隧道衬砌空洞检测方法

隧道衬砌内部空洞等病害检测已经成为隧道检修人员的主要工作之一。本文提出一种将探地雷达与深度学习相结合的隧道衬砌空洞检测方法,通过雷达探测和仿真模拟,得到大量衬砌雷达图像,并对图像进行标注和制作数据集。基于YOLOv5(You Only Look Once version 5)目标检测模型,结合数据集目标特征,提出一种检测衬砌空洞的算法,引入特征融合模块提高网络感受野,并采用K-means聚类算法提高检测准确率。通过现场检测,本文的检测方法准确率达到了97.7%,准确可靠,可在工程中进行应用。

光束倾角对激光深熔焊304不锈钢焊缝力学性能及熔池流动的影响

在激光深熔焊接中光束倾角会直接影响匙孔形态,光束倾角对熔池流动也具有一定的影响.采用激光深熔焊接白板试验结合“半三明治”熔池流动直接观测试验,以激光倾角作为变量,研究其对304不锈钢激光深熔焊接焊缝力学性能及熔池流动的影响.结果表明,在焊缝的力学性能上,不同激光倾角对焊缝上、中部的影响差异性较小,对下部的影响较大,焊缝底部拉伸件出现较多气孔缺陷,正激光入射角下的焊缝抗拉强度和断后伸长率小于负激光入射角.正激光入射角下“上小下大”的匙孔形貌使其底部易产生涡流,不利于气泡的排出,且匙孔坍塌频率较负激光入射角大,导致熔池稳定性较差,焊缝气孔缺陷的形成概率呈现为正激光入射角高于负激光入射角态势.

基于非均质雷达图谱的沥青路面结构损伤识别技术

基于雷达图谱与深度神经网络的沥青路面结构损伤自动辨识方法存在数据量少且种类不均衡的问题,识别准确性与稳定性仍有待提高。提出基于非均质雷达图谱的路面结构损伤识别技术。采用探地雷达采集沥青路面结构裂缝与层间不连续病害,获取实测剖面图;基于时域有限差分法,模拟裂缝与层间不连续在匀质模型中的回波特征,与实测图谱组成数据集1#;基于芯样CT扫描图构建“沥青-集料”二相介质模型,模拟裂缝与层间不连续在二相介质模型中的回波特征,与实测图谱组成数据集2#;采用数据集1#和2#,分别训练YOLO v5深度神经网络。研究结果表明:数据集1#和2#在YOLO v5模型测试集上的m AP@0.5为93.79%与96.33%,证明非均质图谱特征可丰富网络训练样本,并提高深度学习模型识别的准确性。

基于FCOS算法的地下目标重建方法

针对从复杂多样的探地雷达(GPR)成像中检测和定位被埋藏的物体会耗费大量人力时间成本的问题,提出一种基于深度学习的方法。采用一阶全卷积目标检测算法(FCOS)对任意目标进行定量分析,然后对目标区域进行跟踪与聚类标记,曲线拟合获取地下目标的精确位置,重构被埋藏的地下目标信息。仿真结果表明,该方法避免了传统处理算法所需的对数据进行复杂的计算,能够快速检测到目标,并且能对目标的位置与介电属性进行高精确度估计,在深度上的定位误差不大于3 cm。该方法有效实现了地下场景重构目标的位置、深度和大小。