Reliability Modelling and Analysis of Redundant Systems Connected to Supporting External Device for Operation Attended by a Repairman and Repairable Service Station

In this paper, probabilistic models for three redundant configurations have been developed to analyze and compare some reliability characteristics. Each system is connected to a repairable supporting external device for operation. Repairable service station is provided for immediate repair of failed unit. Explicit expressions for mean time to system failure and steady-state availability for the three configurations are developed. Furthermore, we compare the three configurations based on their reliability characteristics and found that configuration II is more reliable and efficient than the remaining configurations.

Using a rigid lens as endocapsular supporting device in cataract surgery for moderate subluxated cataracts

Background:To present a surgical technique using a rigid intraocular lens as endocapsular supporting device in manual small incision cataract surgery(MSICS)for treating mild-moderate subluxated cataracts.Methods:In our technique,a single-piece rigid polymethyl methacrylate(PMMA)lens was implanted in the bag following the nucleus removal,with its axis vertical to the zonular dialysis.This endocapsular-implanted IOL stretched the bag and provided sufficient stability and lens centration.This technique was performed in 19 eyes with subluxated cataracts,with zonulysis of≤120 degree and nuclear sclerosis of grade≤3.Mean follow-up time was 9.8 months.Results:All eyes had endocapsular IOL implantation during surgery.Intraoperative extension of the dialysis did not occur in any eye.The IOL was placed in the bag in all but 1 case,in which dislocation of the IOL haptic into the vitreous occurred.Though the IOL was slightly decentered in 3 cases,it kept stable.All patients were asymptomatic.Conclusions:This approach provides a simplified and practical strategy for surgically managing subluxation with mild-moderate zonular loss.

A Novel System for Recognizing Recording Devices from Recorded Speech Signals

The field of digital audio forensics aims to detect threats and fraud in audio signals.Contemporary audio forensic techniques use digital signal processing to detect the authenticity of recorded speech,recognize speakers,and recognize recording devices.User-generated audio recordings from mobile phones are very helpful in a number of forensic applications.This article proposed a novel method for recognizing recording devices based on recorded audio signals.First,a database of the features of various recording devices was constructed using 32 recording devices(20 mobile phones of different brands and 12 kinds of recording pens)in various environments.Second,the audio features of each recording device,such as the Mel-frequency cepstral coefficients(MFCC),were extracted from the audio signals and used as model inputs.Finally,support vector machines(SVM)with fractional Gaussian kernel were used to recognize the recording devices from their audio features.Experiments demonstrated that the proposed method had a 93.4%accuracy in recognizing recording devices.

Optimal timing of same-admission orthotopic heart transplantation after left ventricular assist device implantation

AIM To investigate the impact of timing of same-admission orthotopic heart transplant(OHT) after left ventricular assist device(LVAD) implantation on in-hospital mortality and post-transplant length of stay.METHODS Using data from the Nationwide Inpatient Sample from 1998 to 2011, we identified patients 18 years of age or older who underwent implantation of a LVAD and for whom the procedure date was available. We calculated in-hospital mortality for those patients who underwent OHT during the same admission as a function of time from LVAD to OHT, adjusting for age, sex, race, household income, and number of comorbid diagnoses. Finally, we analyzed the effect of time to OHT after LVAD implantation on the length of hospital stay post-transplant.RESULTS Two thousand and two hundred patients underwent implantation of a LVAD in this cohort. One hundred and sixty-four(7.5%) patients also underwent OHT duringthe same admission, which occurred on average 32 d(IQR 7.75-66 d) after LVAD implantation. Of patients who underwent OHT, patients who underwent transplantation within 7 d of LVAD implantation("early") experienced increased in-hospital mortality(26.8% vs 12.2%, P = 0.0483) compared to patients who underwent transplant after 8 d("late"). There was no statistically significant difference in age, sex, race, household income, or number of comorbid diagnoses between the early and late groups. Post-transplant length of stay after LVAD implantation was also not significantly different between patients who underwent early vs late OHT. CONCLUSION In this cohort of patients who received LVADs, the rate of in-hospital mortality after OHT was lower for patients who underwent late OHT(at least 8 d after LVAD implantation) compared to patients who underwent early OHT. Delayed timing of OHT after LVAD implantation did not correlate with longer hospital stays post-transplant.

A Hierarchical Modeling and Fault Diagnosis Method for Complex Electronic Devices

Due to the shortcomings of the diagnosis systems for complex electronic devices such as failure models hard to build and low fault isolation resolution, a new hierarchical modeling and diagnosis method is proposed based on multisignal model and support vector machine （SVM）. Multisignal model is used to describe the failure propagation relationship in electronic device system, and the most probable failure printed circuit boards （PCBs） can be found by Bayes inference. The exact failure modes in the PCBs can be identified by SVM. The results show the proposed modeling and diagnosis method is effective and suitable for diagnosis for complex electronic devices.

A Method for Forecasting Credit Risk of Global Device Purchasing

With the development of the Internet and E commerce, enterprises can achieve global device purchasing with a good cost performance. But the credit risk is the key factor in selecting a device provider. Credit risk involves many qualitative and quantitative factors. We construct a multi agent credit rating model system based on CSCW, which organically combines the people's aptitude and the capability of machines. Enterprises can use this credit rating system for forecasting and defeating the credit risk of global device purchasing.

Percutaneous Endoscopic Gastrostomy (PEG) Tube Placement in Patients with Continuous-Flow Left Ventricular Assist Devices (LVAD)

Introduction: Inadequate nutritional support after LVAD placement is known to increase postoperative infections and to decrease survival. LVAD patients with prolonged mechanical ventilation and complicated postoperative recovery requiring prolonged mechanical ventilation may require long-term tube feedings. Placement of a PEG requires knowledge of the location of the LVAD pocket and driveline to avoid device infection and injury. Methods: Between August 2008 and December 2011, 39 patients underwent HeartMate II LVAD placement in our institution. Among them, 5 patients underwent PEG tube placement for long-term nutritional support. Procedure management consisted of cessation of anticoagulation and correction of abnormal coagulation;a cardiothoracic surgeon or intensivist in the operating room to communicate with the surgeon who performed the PEG procedure;and VAD coordinator or perfusionist in the operating room to assist in monitoring the VAD. Data were retrospectively analyzed to investigate complications related to the PEG placement. Results: The studied patients consisted of 3 males and 2 females with mean age of 58 +/﹣5.0. The interval of LVAD to PEG placement was a mean 21 +/﹣8.8 days. PEG was successfully performed in the operating room in all patients. There were no LVAD device or driveline injuries related to the PEG procedure. There were no postoperative short-term or long-term PEG related complications such as acute gastric bleeding or dislodgement of the PEG tube. Conclusions: PEG placement for HeartMate II LVAD patients can be done without increasing the risk of device or intraabdominal organ injury with carefully coordinated efforts from both the mechanical support team and surgical services.

Outcomes of continuous flow ventricular assist devices

Heart transplantation is commonplace, the supply is limited. Many exciting changes in the field of mechanical circulatory support have occurred in the past few years, including the axial flow pump. Left ventricular assist device(LVAD) therapy is ever evolving. As the use of LVAD therapy increases it is important to understand the indications, surgical considerations and outcomes.

To ventricular assist devices or not:When is implantation of a ventricular assist device appropriate in advanced ambulatory heart failure?

Advanced heart failure has been traditionally treated via either heart transplantation,continuous inotropes,consideration for hospice and more recently via left ventricular assist devices(LVAD).Heart transplantation has been limited by organ availability and the futility of other options has thrust LVAD therapy into the mainstream of therapy for end stage heart failure.Improvements in technology and survival combined with improvements in the quality of life have made LVADs a viable option for many patients suffering from heart failure.The question of when to implant these devices in those patients with advanced,yet still ambulatory heart failure remains a controversial topic.We discuss the current state of LVAD therapy and the risk vs benefit of these devices in the treatment of heart failure.

复杂信息环境下的情报快速反应机制研究

在科技飞速发展和大国博弈日益白热化的背景下,情报成为抢占国家发展先机的重要工具之一。在复杂信息环境的情报生产新环境和决策新要求下,本文以如何实现情报支撑国家战略决策为研究问题,通过文献调研与案例分析等方法,在总结梳理相关理论和实践经验的基础上,对情报快速反应机制的内涵、特征和决策支撑场景进行深入探究。本文创新性地提出一套适用于复杂信息环境下的“3+5+9情报快速反应机制”,以“早发现、早预判、早报告、早决策、早应对”为五大核心目标,以“联动协调、信息监测、信息资源、情报分析、应急处置、技术支撑、专家协作、组织保障、跟踪评估监督”为九大支撑子体系,适用于常态化监测、回应关切和突发应急三类重要决策支撑场景的情报工作机制,以期为未来相关实践提供较为扎实的理论基础。

非线性曲面梁形态优化及恒压支撑装置设计

基于超前支护设备顶梁支撑结构研究一种恒压支撑装置的设计方法,恒压支撑装置由正刚度线性弹簧、负刚度非线性平面曲梁及承压气囊组合而成。通过对巷道顶板应力场分析,得到支撑结构的边界条件;利用B样条曲线简述负刚度非线性平面曲梁的特点;基于遗传算法与非线性有限元法对负刚度非线性平面曲梁进行形态优化设计;依据恒压支撑装置的工作原理,对线性螺旋弹簧刚度/强度特性进行分析与设计;对恒压支撑装置的零部组件进行设计,实现支撑装置输出压强大小恒定及自我保护功能。恒压支撑装置设计方法为综掘巷道超前支护研制提供了有力技术支撑。

水产养殖作业船转塘装置的设计

水产养殖作业船可以用于水草清理、饵料投放、施药、水质监测等,其工作范围不只限于单块水塘,但相邻水塘共用时往往需要通过人力来实现养殖作业船的转塘,这一过程费时费力。对此,设计一种养殖作业船转塘装置,通过两侧齿轮与架空齿条的啮合及底部滚轮与转移轨道的导向来形成对作业船的三点支撑。为保证养殖作业船能无阻碍地通过堤坝,特地设计计算了架空齿条上坡段、水平段和下坡段的高度和角度。将养殖作业船的螺旋桨改造成明轮,其为转塘爬坡提供动力的同时也能有效防止水草缠绕。现有应用表明,该装置大大提升了水产养殖过程中的转塘效率,既提高了作业船的利用率,也降低了总体投入成本,因此具有一定的推广价值。

古树断裂倒伏风险评估原理与防护设计

强度缺陷和风雪荷载是导致古树断裂倒伏的两大因素。古树的风险评估就是通过望诊、检测、探根及测绘,找出安全隐患、确定缺陷位置及大小、分析古树受力破坏方式、测算剩余强度和稳定性,而古树的安全防护就是设计安装必要的支撑与拉纤来防止这种破坏发生。本文阐述了古树风险评估的原理和方法,并介绍了不同类型支撑与拉纤的设计和应用。

主动安全液压支架顶梁装置结构设计与分析

煤壁片帮与顶板冒落是影响煤矿安全开采的重要因素,目前常见的液压支架有效支护面积大,移架脱离顶板时间长,很容易发生煤壁片帮与顶板冒落造成支架再次支护失稳等问题。通过对顶板失稳机理进行分析,建立了等效砌体梁结构的数学模型,计算得到了回采工作面顶板发生破坏的强度条件以及支护面积对顶板发生破坏的影响,同时提出了主动安全液压支架顶梁装置的设计,对现有液压支架顶梁在满足原有功能的基础上,设计了顶梁装置,实现了对顶板的有效支护和相对主梁的步足式移动,达到了液压支架主动安全支护的目的,从而满足降低砌体梁发生破坏的概率。通过对ZY4800/18/38液压支架的改进,并对其进行典型状态下顶梁装置有限元分析,结果满足设计要求。

大跨度钢箱系杆拱桥减隔震措施对比研究

以某跨河大跨度钢箱系杆拱桥为研究对象,研究不同措施下桥梁的减隔震性能。通过“m”法,利用桥梁有限元软件Midas Civil进行动力分析;通过人工合成地震波,采用FDB模型、粘滞阻尼器MAXWELL模型进行模拟,对大跨度钢箱系杆拱桥进行非线性时程分析,对比分析摩擦摆支座、速度锁定器、拉索减震支座的减震效果。研究结果表明:三种减隔震措施下,墩柱所受的轴力差异较小,摩擦摆支座及拉索减震支座所受的剪力、弯矩差异较小,速度锁定器作用下,墩柱所受的剪力及弯矩差异较大。通过对比分析,选用摩擦摆支座能较好地满足工程需求,减震效果良好。

结构实验综合实验平台设计

结构实验是土木工程专业一门必修的实验课程,钢筋混凝土梁的抗弯和抗剪实验是其中的一项重要内容。设计了一体支座、对中系统、垂直度校正器、上梁装置、试件加载系统,最后对实验平台承载力进行了验算。实验平台采用2种形式,一种为自平衡式,另一种为地槽固定式。该实验平台除了用于梁的抗弯实验之外还可以用于柱的抗压实验。

基于临时支护新装置的工序优化与支护性能分析

针对掘进工作面存在的掘支平行作业难、用时比重失调问题,为实现平行作业、快速支护,设计了新的临时支护装置,具有尺寸可调、快速响应、及时支护的特点。采用理论分析加数值模拟的方法进行研究;介绍了装置的结构设计;以新巨龙煤矿综掘施工技术为例进行工艺优化,从理论上提出一种分区平行作业的施工技术;通过顶板两端简支岩梁力学模型,展开装置临时支护作用机理分析;并对装置的支护性能进行结构静力学分析。结果表明:在巷道顶板松动范围0~3.30 m时,装置支护所需承受的载荷为158.40 kN;仿真得到最大等效应力为57.37 MPa,在装置顶梁下端与耳座位置交接处,最大位移量出现在中间梁上端中部,为0.30 mm,装置的结构设计能满足支护要求。此研究可为实现快速掘进的平行作业,高效支护和安全生产,提供有益参考。

小样本下基于GM-SVR方法的航空保障特种装置可靠性评估

航空保障特种装置的可靠性评估面临失效样本数据偏少的问题。为更加准确评估小样本情况下的可靠性,采用改进的平均秩次法计算样本的经验分布函数,在此基础上提出一种基于GM-SVR的三参数威布尔分布估计方法。该方法利用灰色模型(GM)在位置参数上的优势和支持向量回归(SVR)在小样本下的良好效果,对威布尔分布的3个参量进行精确估计。采用MATLAB工具箱对模型进行仿真实验,结果表明:GM-SVR方法在故障数据样本较少情况下,参数估计精度高于传统的概率统计方法。以喷气偏流板为例,计算了威布尔分布的形状参数、尺度参数和位置参数,得到相关系数为0.9953,均方根误差为0.038,证明了在小样本情况下GM-SVR方法的拟合精度良好,可对航空保障特种装置的可靠性进行准确评估。

数字健康干预用于食管癌患者居家营养支持的范围综述

目的对数字健康干预在食管癌患者营养支持中的应用研究进行范围综述,以识别数字健康的干预形式、内容要素和应用效果,为未来该领域相关研究的开展提供参考。方法系统检索PubMed、Web of Science、EBSCO、中国知网、维普数据库、万方数据库及中国生物医学数据库,检索时间为建库至2023年9月1日,对纳入文献进行汇总分析。结果共纳入18篇文献,包括6篇英文文献及12篇中文文献。基于相关文献分析认为,对于食管癌患者居家营养支持的数字健康干预,主要形式有通讯软件、应用程序及网站平台;干预内容要素主要涉及成立营养管理团队、居家肠内营养指导、构建个体化饮食方案、建立个人营养档案、交流互动、心理疏导及功能锻炼等;结局评价指标主要包括生理相关指标、心理指标、生活质量、自我管理、安全性与可行性指标等。结论数字健康干预拓展了食管癌患者营养支持的形式,能够改善食管癌患者的营养状况,且多学科、多要素联合的干预方式更受青睐。数字健康干预在食管癌患者营养支持中具有较高的接受度和满意度,但仍面临许多挑战。今后可基于“互联网+护理服务”和分级诊疗管理模式,进一步拓展数字健康干预的形式和内容,为患者提供更加便捷、专业、规范的护理服务,以改善食管癌患者营养支持的干预效果。

新型竖齿摇摆自复位剪力墙抗震性能研究

底端固结在基础上的剪力墙,在地震中墙角最易损伤破坏,且耗能较差,震后不宜修复。提出了一种新型竖齿摇摆自复位剪力墙(self-centering vertical tooth swing shear wall,SCVT-SW)体系。SCVT-SW体系由钢筋混凝土墙体、碟簧复位装置、软钢阻尼器以及竖齿摇摆支座等组成,所有部件均通过高强螺栓相连,便于施工和震后对受损部件更换。SCVT-SW体系的工作原理是:在地震过程中,由墙体两侧的竖向碟簧复位装置提供墙体摇摆复位弯矩,软钢阻尼器消耗地震能量,竖齿摇摆支座在提供水平抗剪能力并将墙体受到的水平作用力传递到墙体基础的同时起到固定铰支座的作用。理论分析给出了SCVT-SW体系中墙体截面的正截面承载力计算公式。通过非线性数值模拟,对新型剪力墙与普通剪力墙的受力性能进行了对比,设计了9组不同工况的对比参数。结果表明:与普通剪力墙相比,SCVT-SW骨架曲线没有明显下降段,残余变形更小;SCVT-SW体系的正截面承载力随着墙角两侧碟簧装置的预压力的增大而提高,最大提升27.8%;残余变形随碟簧装置刚度增大而减小,工况7比工况5减小了19.4%,工况8比工况5减小了46.9%,因此通过增大碟簧装置预压力与碟簧装置刚度来减小SCVT-SW的残余变形,提高复位能力的效果是显著的。