Simultaneous Approximation by Baskakov-Durrmeyer Operator

In this paper, we investigate the degree of approximation by Baskakov_Durrmeyer operator for functions which derivatives have only discontinuity points of the first kind on [0,∞) with exponential growth.

EQUIVALENT THEOREMS ON SIMULTANEOUS APPROXIMATION BY COMBINATIONS OF BERNSTEIN OPERATORES

In this paper we give equivalent theorems on simultaneous approximation for the combinations of Bernstein operators by r-th Ditzian- Totik modulus of smoothness w^rφλ （f, t）（0 ≤ λ≤ 1）. We also investigate the relation between the derivatives of the combinations of Bernstein operators and the smoothness of derivatives of functions.

Passively Q-Switched Nd,Cr:YAG Laser Simultaneous Dual-Wavelength Operation at 946 nm and 1.3μm

A diode-end-pumped Q-switched high-efficiency Nd, Cr：YAG laser with simultaneous dual-wavelength emission at 946nm and 1.3μm is demonstrated. The maximum output power of 1.93 W with simultaneous dual-wavelength operation is achieved at an absorbed pump power of 13.32 W and an absorbed slope efficiency of 15.15%. The maximum optical-optical efficiency is 14.49% with pulse widths of 16.38ns at 946nm and 26.65ns at 1.3μm. A maximum total repetition rate of 43.25 kHz is obtained.

CFD Based Simulation of LNG Release during Bunkering and Cargo Loading/Unloading Simultaneous Operations of a Containership

In order to reduce waiting time in port for large LNG （liquefied natural gas） fueled ships, it is suggested that LNG STS （ship to ship） bunkering and cargo loading/unloading should be carried out simultaneously. This study investigated the safety zone of an LNG bunkering vessel with 10,000 cubic meters capacity transferring LNG fuel to an LNG fueled 18,000 TEU containership. Four LNG leakage scenarios were identified based on failure frequencies analysis of piping systems and severity of consequence, three-dimension CFD software FLACS was adopted to calculate flammable cloud dispersion after LNG leakage. As a result, we obtained a rectangle dangerous zone （41.3 m ~ 126 m）, outside of this dangerous zone can be def＇med as safety zone. It is concluded that safety zone of LNG STS bunkering and cargo loading/unloading SIMOPS （simultaneous operations） cannot keep the same, there are different results for different designs and operation locations. Due to high frequencies and severe consequences, two typical scenarios, the leakage of LNG hose and the natural gas releases from bunkering tank＇s safety relief valve during bunkering, cannot be ignored in similar study.

Simultaneous operation for cardiac disease and gastrointestinal malignancy

AIM: To investigate the safety of performing simulta-neous cardiac surgery and a resection of a gastrointes-tinal malignancy. METHODS: Among 3664 elective cardiac operations performed in adults at Kagoshima University Hospi-tal from January 1991 to October 2009, this study reviewed the clinical records of the patients who un-derwent concomitant cardiac surgery and a gastroin-testinal resection. Such simultaneous surgeries were performed in 15 patients between January 1991 and October 2009. The cardiac diseases included 8 cases of coronary artery disease and 7 cases with valvular heart disease. Gastrointestinal malignancies included 11 gas-tric and 4 colon cancers. Immediate postoperative andlong-term outcomes were evaluated. RESULTS: Postoperative complications occurred in 5 patients(33.3%), including strokes(n = 1), respiratory failure requiring re-intubation(n = 1), hemorrhage(n = 2), hyperbilirubinemia(n = 1) and aspiration pneu-monia(n = 1). There was 1 hospital death caused by the development of adult respiratory distress syndrome after postoperative surgical bleeding followed aortic valve replacement plus gastrectomy. There was no car-diovascular event in the patients during the follow-up period. The cumulative survival rate for all patients was 69.2% at 5 years. CONCLUSION: Simultaneous procedures are accept-able for the patients who require surgery for both car-diac diseases and gastrointestinal malignancy. In par-ticular, the combination of a standard cardiac operation, such as coronary artery bypass grafting or an isolated valve replacement and simple gastrointestinal resection, such as gastrectomy or colectomy can therefore be safely performed.

ON SHAPE-PRESERVING PROPERTIES AND SIMULTANEOUS APPROXIMATION OF STANCU OPERATOR

In the present paper, the shape-preserving properties and the monotonicity for convex functions of Stancu operator are given. Moreover, the simultaneous approximation problems of this operator are also considered.

Simultaneous Approximation for Szsz-Mirakian-Stancu-Durrmeyer Operators

The aim of this work is to generalize Szasz-Mirakian operator in the sense of Stancu-Durrmeyer operators. We obtain approximation properties of these operators. Here we study asymptotic as well as rate of convergence results in simultaneous approximation for these modified operators.

SIMULTANEOUS APPROXIMATION BY BERNSTEIN-SIKKEMA OPERATORS

In this paper, we investigate the simultaneous approximation of Bernstein- Sikkema operators, and establish the direct and equivalent theorems by using the Ditzian-Totik modulus of smoothness.

EQUIVALENT THEOREMS ON SIMULTANEOUS APPROXIMATION BY COMBINATIONSOF GAMMA OPERATORS

In this paper, some equivalent theorems on simultaneous approximation for combinations of Gamma operators by weighted moduli of smoothness ωφλ^r（f,t）wφ^s（0≤λ≤1）are given. The relation between derivatives of combinations of Gamma operators and smoothness of derivatives of functions is also investigated.

EQUIVALENCE THEOREM ON WEIGHTED SIMULTANEOUS L-APPROXIMATION BY MEANS OF SZASZ-KANTOROVICH OPERATORS AND BASKAKOV-KANTOROVICH OPERATORS

The intention of this paper is to give direct and converse results on weighted simultaneous approximation by means of Sz(?)sz-Kantorovich operators and Baskakov-Kantorovich operators in L_p-norms using the weighted Ditzian-Totik modulus of smoothness.

船舶采用LNG加注与装卸货同步作业风险评估研究

为了有效评估沿海港口船舶采用LNG加注与装卸货同步作业的潜在风险和相应缓解措施,本文选定上海洋山港二期码头为作业地点,以一艘20 000m3LNG加注船为14 800TEU双燃料集装箱船实施LNG加注并同时进行装卸货作业为研究对象,基于国内外广泛认可的风险评估方法进行危险源辨识和失效概率分析,拟定了4个LNG泄漏场景,采用三维计算流体力学软件FLACS分析了LNG泄漏后的可燃气体对两船的波及范围,同时考虑到集装箱装卸货对LNG加注船及作业的影响,提出了LNG加注与装卸货同步作业的限制区域、警戒区域及安全保障措施建议。

滑翔制导炮弹多炮齐射协同弹道规划与协作范围确定方法

针对滑翔制导炮弹多炮齐射打击固定目标的协同攻击场景,为充分发挥整体控制能力,增强打击效果,研究着眼于弹群的协同方案弹道规划问题。首先,考虑到攻击不同距离目标时飞行方案的侧重点与弹道特性差异,为滑翔制导炮弹进行战区划分,并在此基础上建立寻优指标因战区而异的全弹道协同规划模型。其次,针对实战中的战斗队形配置问题,提出一种简单通用的协作范围确定方法。随后,针对现有协同方式在处理多阶段规划问题时存在的适用性或最优性方面的局限,提出一种双层自适应协同策略。最后,分析特殊作战任务引入的额外约束条件对战区划分与协作范围的影响。仿真结果表明,所提方法可以简捷有效地确定可行工况,辅助战斗队形的配置;同时,相比于传统的分布式策略,在所提的协同策略作用下,不同战区内的方案弹道均具有优越性。

Effectiveness and safety of early lens extraction during par plana vitrectomy for proliferative diabetes retinopathy with mild cataract:a randomized clinical trial

●AIM:To evaluate the effectiveness and safety of early lens extraction during pars plana vitrectomy(PPV)for proliferative diabetic retinopathy(PDR)compared to those of PPV with subsequent cataract surgery.●METHODS:This multicenter randomized controlled trial was conducted in three Chinese hospitals on patients with PDR,aged>45y,with mild cataracts.The participants were randomly assigned to the combined(PPV combined with simultaneously cataract surgery,i.e.,phacovitrectomy)or subsequent(PPV with subsequent cataract surgery 6mo later)group and followed up for 12mo.The primary outcome was the change in best-corrected visual acuity(BCVA)from baseline to 6mo,and the secondary outcomes included complication rates and medical expenses.●RESULTS:In total,129 patients with PDR were recruited and equally randomized(66 and 63 in the combined and subsequent groups respectively).The change in BCVA in the combined group[mean,36.90 letters;95%confidence interval(CI),30.35–43.45]was significantly better(adjusted difference,16.43;95%CI,8.77–24.08;P<0.001)than in the subsequent group(mean,22.40 letters;95%CI,15.55–29.24)6mo after the PPV,with no significant difference between the two groups at 12mo.The overall surgical risk of two sequential surgeries was significantly higher than that of the combined surgery for neovascular glaucoma(17.65%vs 3.77%,P=0.005).No significant differences were found in the photocoagulation spots,surgical time,and economic expenses between two groups.In the subsequent group,the duration of work incapacity(22.54±9.11d)was significantly longer(P<0.001)than that of the combined group(12.44±6.48d).●CONCLUSION:PDR patients aged over 45y with mild cataract can also benefit from early lens extraction during PPV with gratifying effectiveness,safety and convenience,compared to sequential surgeries.

改进烟花算法求解同时送取货选址路径问题

针对同时送取货的选址路径问题(Location-routing Problem with Simultaneous Pickup and Delivery,LRPSPD),设计一种改进烟花算法(Improved Firework Algorithm,IFWA)求解。首先,考虑仓库建设、车辆启用、车辆路径等成本因素,建立最小成本的LRPSPD模型,该模型强调需求点的送货需求和取货需求只能由一辆车同时进行服务。其次,设计一种改进烟花算法,该算法结合贪心聚类算法生成初始解,由烟花爆炸算子操作生成邻域解,利用变异操作协助产生新种群。最后,通过使用混合免疫算法、模拟退火算法求解相同算例,对结果进行分析比较,验证模型的可行性和改进算法的有效性。

基于目标检测的室内动态场景同步定位与建图

为了提高室内动态场景下定位与建图的准确性与实时性,提出了一种基于目标检测的室内动态场景同步定位与建图(simultaneous localization and mapping,SLAM)系统。利用目标检测的实时性,在传统ORB_SLAM2算法上结合YOLOv5目标检测网络识别相机图像中的动态物体,生成动态识别框,根据动态特征点判别方法只将识别框内动态物体上的ORB特征点去除,利用剩余特征点进行相机位姿的估计,最后建立只含静态物体的稠密点云地图与八叉树地图。同时在机器人操作系统(robot operating system,ROS)下进行仿真,采用套接字(Socket)通信方式代替ROS中话题通信方式,将ORB_SLAM2算法与YOLOv5目标检测网络相结合,以提高定位与建图的实时性。在TUM数据集上进行多次实验结果表明,与ORB_SLAM2系统相比,本文系统相机位姿精确度大幅度提高,并且提高了每帧跟踪的处理速度。

基于多传感器融合SLAM的ROS服务机器人研究

为提升自主导航精度,使用Jetson Nano控制器,采用同步定位与地图构建和路径规划算法,融合轮式里程计、激光雷达和惯性测量单元等多传感器信息,实现精确的单点和多点自主导航。采用机器人操作系统搭建自主导航框架,使用基于图优化的cartographer算法实现环境地图构建与机器人位姿估计,采用A*算法作为全局路径规划算法,同时利用基于g2o优化的TEB算法实现环境突变时的局部路径规划。实验结果表明,基于图优化的cartographer算法建图效果优于常见的基于粒子滤波的Gmapping算法。基于g2o优化的TEB算法可避免动态窗口算法在局部路径规划中机器人被挟持的情况,提升智能机器人地图构建和路径规划的准确性。

ICP-AES法测定硫酸中砷、铅、铁、汞的含量

文章提出一种硫酸中铅、铁、汞、砷含量的新测定方法,采用ICP-AES来测定硫酸中的铅、铁、汞、砷元素,并且做了条件试验,加入已知量元素进行回收试验、精密度试验以及方法比对,此方法快速便捷、测定准确可靠,相对标准偏差为4.9×10^(-5)%~5.3×10^(-5)%,加标回收率为97.33%~102.38%,测定范围0.0001%~0.0090%。

激光雷达的AGV机器人系统设计与研究

针对自动导引车(automatic guided vehicle,AGV)机器人缺乏智能化和通用性的问题,在机器人操作系统(robot operating system,ROS)平台开发一款基于激光雷达构建地图和自主导航的履带型AGV样机.首先,采用履带式行走系统增强AGV的通过性,并配置单线激光雷达以降低系统成本.在此基础上,尝试使用Cartographer和Gmapping这两种主流的即时定位与地图构建(simultaneous localization and mapping,SLAM)算法构建场景地图,并配合路径规划算法实现路径规划和自主导航.试验结果表明,样机所配置的硬件和算法能良好兼容,从而保证AGV机器人能在随机路径的运输任务下,快速有效的构建地图和实现在线导航.

基于ROS和激光雷达SLAM的动态避障研究

针对Gmapping算法不适用于构建大场景地图的问题,采用带有回环检测的Cartographer算法进行即时定位与建图(SLAM)。同时,针对全局路径规划A*算法可以得到全局路径但不能有效躲避动态障碍物、局部路径规划时间弹性带(TEB)算法可以躲避障碍物但规划的路径可能只是局部最优而非全局最优的问题,提出了融合A*算法和TEB算法的导航避障方法。通过多层代价地图中静态层、障碍层和膨胀层的有效结合,为路径规划A*算法和TEB算法提供了便捷的规划环境。对导航环境中静态和动态障碍物进行了研究。试验结果表明,两种路径规划算法融合后可准确躲避静态障碍物、新出现的障碍物和动态障碍物,且能快速到达目标点。

APPROXIMATION BY COMPLEX SZSZ-DURRMEYER OPERATORS IN COMPACT DISKS

In the present paper, we deal with the complex Szasz-Durrmeyer operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth on compact disks. Also, the exact order of approximation is found.