Prenatal diagnosis of isolated lateral facial cleft by ultrasonography and three-dimensional printing:A case report

BACKGROUND Lateral facial clefts are atypical with a low incidence in the facial cleft spectrum.With the development of ultrasonography(US)prenatal screening,such facial malformations can be detected and diagnosed prenatally rather than at birth.Although three-dimensional US(3DUS)can render the fetus'face via 3D reconstruction,the 3D images are displayed on two-dimensional screens without field depth,which impedes the understanding of untrained individuals.In contrast,a 3D-printed model of the fetus'face helps both parents and doctors develop a more comprehensive understanding of the facial malformation by creating more interactive aspects.Herein,we present an isolated lateral facial cleft case that was diagnosed via US combined with a 3D-printed model.CASE SUMMARY A 31-year-old G2P1 patient presented for routine prenatal screening at the 22nd wk of gestation.The coronal nostril-lip section of two-dimensional US(2DUS)demonstrated that the fetus'bilateral oral commissures were asymmetrical,and left oral commissure was abnormally wide.The left oblique-coronal section showed a cleft at the left oral commissure which extended to the left cheek.The results of 3DUS confirmed the cleft.Furthermore,we created a model of the fetal face using 3D printing technology,which clearly presented facial malformations.The fetus was diagnosed with a left lateral facial cleft,which was categorized as a No.7 facial cleft according to the Tessier facial cleft classification.The parents terminated the pregnancy at the 24th wk of gestation after parental counseling.CONCLUSION In the diagnostic course of the current case,in addition to the traditional application of 2D and 3DUS,we created a 3D-printed model of the fetus,which enhanced diagnostic evidence,benefited the education of junior doctors,improved parental counseling,and had the potential to guide surgical planning.

Three-dimensional seismic isolation bearing and its application in long span hangars

Based on the seismic response characteristics of space frame structures,a new type of seismic isolation bearing defined as a three-dimensional seismic isolation bearing（3DSIB） is developed in this paper.The bearing offers excellent properties such as multi-dimensional seismic isolation,reasonable rotation capability,good ability to resist lifting load,uncoupled stiffness in horizontal and vertical directions,etc.In the 3DSIB,the horizontal dimension is designed by combining the Teflon sliding device and helical spring,while the vertical dimension is developed by introducing disk springs or helical springs.The mathematical model of the 3DSIB was established and its performance with the critical parameters was tested on a shaking table.Furthermore,the 3DSIB was applied in a 120 m span hangar structure and simulated using SAP2000 software to evaluate its performance in practical structures.The performance of the structures with and without 3DSIB was compared.It is shown that the hangar structure with 3D bearings achieves a better performance.The axial force and acceleration response of the structures with 3DSIB are effectively reduced,while the displacement response of the bearing is within the predetermined range.

Research and application on three-dimensional seismic and vibration isolation for building

This paper presents the study of a three-dimensional(3D) isolation system.Firstly,the authors investigated the effects of an innovative 3D isolator,which was composed of a connecting plate,a rubber pad for vibration isolation in the vertical direction and a horizontal rubber bearing for seismic isolation in both horizontal directions.Secondly,the authors designed such a vibration isolation system and installed it underneath two specific residential buildings which were built directly over an existing subway communication hub platform in Beijing.These buildings required good performance vibration and seismic isolation system to reduce the impact from the running of nearby subway trains.Finally,in situ tests were conducted for both the isolated and the non-isolated buildings for the purpose of comparison.The test results showed that the maximum acceleration response level of the isolated superstructure is reduced by 10% as compared to that of the platform.The maximum attenuation of vibration reaches up to 25 dB.The 3D system explored in this paper is very effective in control and suppression of building vibration induced by earthquakes or running of trains.

Study on a conical bearing for acceleration-sensitive equipment

Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-sensitive systems or equipment.Meanwhile,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance concerns.As a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system damping.Moreover,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various conditions.According to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement responses.Finally,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.

Vibration Isolation Characteristics of Impedance-balanced Ship Equipment Foundation under Unbalanced Excitation

A new type of impedance-balanced ship equipment foundation structure based on the principle of impedance balancing using a“discontinuous panel-vibration isolation liquid layer-foundation structure”is proposed to solve the problem of poor low-frequency vibration isolation of the foundation under unbalanced excitation of shipboard equipment.Based on the finite element method,the influence of characteristic parameters of the foundation panel structure on its vibration reduction characteristics under unbalanced excitation is explored.The results show that the vibration isolation level of the impedance-balanced foundation is 10 dB higher than the traditional foundation in the low-frequency band of 10-500 Hz when subjected to combined excitation of concentrated force and moment.Increasing the thickness of the impedance-balanced foundation panel can enhance the isolation effect.Increasing the number of sub-panels can effectively reduce the vibration response of the foundation panel and enhance the isolation performance of the foundation.The connection stiffness between sub-panels has a small effect on the isolation performance of the foundation.

Tri-directional shaking table tests of vibration sensitive equipment with static dynamics interchangeable-ball pendulum system

Recently, the high-tech industry has become a key industry for economic development in many countries. However, vibration sensitive equipment located in these industrial buildings is vulnerable during earthquakes, which may cause huge economic loss. In this study, an innovative isolator for safeguarding the vibration sensitive equipment, namely, the static dynamics interchangeable^all pendulum system （SDI-BPS） is proposed and investigated to examine its protective capability for the vibration sensitive equipment during earthquakes through a series of tri-directional shaking table tests. The experimental results illustrate that the SDI-BPS isolator can provide significant damping to rolling types of base isolation systems for reducing the bearing displacement and size, and avoid the stress concentration, which can cause damage or scratches on the rolling surface of the isolator, to prolong its life span of service. The SDI-BPS isolator also provides excellent capability in protecting the vibration sensitive equipment and exhibits a stable behavior under long terms of service loadings and earthquakes.

Application of Intelligent Equipment on Novel Coronavirus Pneumonia Designated Hospital

Objective: To explore the application of intelligent equipment in non-negative pressure isolation ward for COVID-2019 patients. Method: From February 1 to March 17, 2020, intelligent equipment, such as communication interaction system, intelligent disinfection robot, delivering robot, were used in non- negative pressure isolation ward of COVID-2019. With the help of communication interaction system to supervise the implementation of infection prevention and control, and observe the incorrect situation of pee use and personal behavior before and after the implementation. The disinfection robot and meal delivery robot were used in ward disinfection and life nursing combined with nursing practice. Result: Through the supervision of communication interaction system, the frequency of pee use and personal behavior was reduced. The frequency of bad articles before and after improvement was wearing protective clothing (2.80%/0.84%), taking off protective clothing (5.87%/0.84%), personal behavior observation (8.38%/1.90%), P < 0.01. The robot disinfected and delivered medicine for 912.5 h, saving 225 shifts of nursing staff. Conclusion: Intelligent equipment is a good option for infection control in isolation ward of COVID-2019. It can not only reduce the workload of health workers, but also the cross-infection.

Design of Dismantling and Recycling Equipment for Junction Boxes of Waste Crystal Silicon Photovoltaic Modules

The dismantling and recycling of junction boxes,which is an important part of the photovoltaic module recycling process,was tested and designed scientifically.The equipment framework was built by three-dimensional simulation,and then the design of dismantling and recycling equipment for junction boxes of waste crystal silicon photovoltaic modules was completed through the experimental test and data analysis.The experimental results show that the initial idea of the dismantling scheme is correct,and the structure is feasible.However,some problems were not considered.This study provides reliable data support for the subsequent equipment development and ensures the smooth development of the subsequent design work.

Application Status and Prospect of Three-Dimensional Printing Technology in the Field of Medical Devices

Three-dimensional(3D)printing technology belongs to a new manufacturing science and has been widely used in various fields of industry.This article will apply 3D printing technology as its main research topic,with emphasis on its application in the field of medical devices and prospects for contribution.

Experiences of Social Isolation in Older Hospitalized Patients with COVID-19 and Their Close Relatives: A Qualitative Study

Background: Proximity between older patients and their close relatives is essential during hospitalisation. During the first wave of the pandemic, the Danish Patient Safety Authority restricted no hospital visitors. Aim: To explore how older patients with COVID-19 and their close relatives experienced physical separation during hospitalization. Method: A qualitative study using semi-structured interviews and thematic analysis was employed. Findings: Six interviews were conducted: three patients with a mean age of 81 years and three close relatives—two daughters and one spouse. The patients felt boredom, loneliness, and a sense of imprisonment, yet they felt safe and satisfied. Isolation was known beforehand from the media. Close relatives emphasised that information, involvement, and collaboration with hospital staff were crucial. Conclusion: Although older patients with COVID-19 and their close relatives widely accept their situation during hospitalization, they experience negative consequences from social isolation.

Development of rocking constraint device with vertical damping capacity for three-dimensional base-isolated frame structures

A new rocking constraint device(RCD)is developed for three-dimensional(3D)base-isolated frame structures by connecting a custom-designed cylinder pair to provide vertical damping with replaceable damping components installed outside the cylinders when the superstructure undergoes translational motion,and rocking constraint capacity when the superstructure is susceptible to rocking.Theoretical formulas for calculating the damping and rocking constraint stiffness of the RCD are proposed.Two series of sinusoidal loading tests are conducted at different loading frequencies and amplitudes to verify the damping and rocking constraint performance of the RCD.The test results show that the cylinder without orifices on its piston can provide the desired damping with a replaceable damping component,and that the RCD can effectively suppress rocking.Although the vertical stiffness of an individual cylinder is affected by the location of the replaceable damping component and loading frequency,the average vertical stiffness of the two cylinders,which determines the rocking constraint stiffness of the RCD,is independent of the two factors.Comparisons of the test and theoretical results indicate that the errors of the proposed formulas for calculating the damping and rocking constraint stiffness of the RCD do not exceed 12.9%and 11.0%,respectively.

电机设备三维隔震试验研究

针对核电设备设计研制了三维隔震支座,以核电设备常用的电机为例,对其三维隔震性能开展了振动台试验研究,获得了电机设备典型部位的隔震动力响应,通过对比振动台台面数据与设备测点位置的数据来验证隔震支座的隔震效果。结果表明:随着输入地震动峰值增大,隔震支座的隔震效率差别微小,隔震效果比较稳定,说明隔震支座对电机设备起到了良好的隔震作用。

自复位浮置物隔震系统的动力试验与数值分析

提出了一种自复位浮置物隔震系统,该系统采用双层正交导轨隔离水平地震,并通过预拉弹簧绳实现自复位。考虑系统摩擦与弹簧绳刚度,建立了自复位浮置物隔震系统的理论模型,完成了不同工况下的隔震系统振动台试验,结果表明输入地震波的加速度峰值越高,隔震系统的隔震率也会相应提升。在输入地震波加速度峰值为0.15、0.2、0.4、0.62 g时,隔震系统平均隔震率分别为50%、58%、75%、82%。在相同峰值的地震波及楼面波地震动输入下,隔震系统均具有良好的隔震效果且能够实现系统自复位。最后建立了浮置物隔震支座-浮置物体系的有限元模型,验证了隔震系统理论模型的有效性。

基于数字孪生和IETM的装备常规故障诊断

装备在实际运行过程中出现的大部分常规故障都是由于人为操作、保养以及环境等因素引起的。常规故障在装备的研制、试验、鉴定以及维保过程中都进行了验证,并有明确的定义,具有明确的故障树分析结论,因而数字孪生可为装备常规故障提供快速、交互性的诊断可能。为提高常规故障诊断的效率和诊断过程的交互式体验感,提出一种基于数字孪生的装备常规故障诊断模型。在此基础上,鉴于交互式电子技术手册(IETM)良好的交互性及用户体验感,设计一种基于孪生数据和IETM的装备常规故障诊断方案。该方案将装备故障树转换为IETM的故障数据模块,存储到IETM数据库中形成故障库。采用故障树分析方法并将装备实时孪生数据作为输入,利用IETM的交互性,通过过程数据模块结合故障数据模块进行步进式故障诊断及隔离引导操作,同时提供维修操作指导。当装备实时孪生数据与故障库定义的故障信息不完全一致时,采用案例分析法计算装备实时孪生数据提供的故障征兆信息与故障库中明确定义的故障征兆信息的相似度,并设定相似度的阈值进行判定;再利用IETM推送对应故障数据模块进行相应的故障诊断隔离引导。

变电站隔离开关操作产生的电磁暂态特征量研究

变电站隔离开关操作产生的电磁骚扰是电力系统二次设备防护的重要内容。基于真型实验场开展了一系列实验,在AIS和GIS内进行了一系列不同电压等级不同容性负载的隔离开关分合闸重复实验。由于隔离开关操作持续时间长,采样率高,采集得到的实测数据十分庞大,为了方便处理实测数据,设计了一种自动计算的模型既能实现隔离开关全过程多次放电脉冲群的特征量提取,也能实现单次击穿波形的分离和计算。计算结果显示AIS隔离开关操作产生的电磁骚扰主频在300~600 kHz,有些文献中测量结果高达几MHz,GIS产生的电磁骚扰在17~20 MHz。暂态电流及其耦合的电磁骚扰主频仅受变电站结构和参数影响,相同实验条件下GIS产生的地电波比AIS幅值更高主频更大振荡更强烈。该实验结果为电力系统开展针对二次设备的电磁防护试验提供了量化参数。

电流互感器抗震性能与隔震试验研究

瓷柱型电气设备是变电站最常见的室外高压电气设备,抗震能力较差,历次震害表明该设备损坏是造成电力系统功能失效的主要原因。对110 kV电流互感器进行振动台试验,原设备与安装滑动自复位隔震支座设备同时进行试验,测定设备在不同地震动强度、不同地震波作用下关键位置加速度、位移和应变响应,分析电流互感器抗震性能和隔震支座隔震效果。研究结果表明,地震动峰值加速度为0.4 g时,电流互感器瓷套管根部最大应力为22.4 MPa,电流互感器加速度放大系数为3~8;滑动自复位隔震支座明显降低了电流互感器自振频率,瓷柱型电气设备瓷套管顶部加速度响应降低了80%以上,瓷套管根部应变响应不同程度地降低,说明滑动自复位隔震支座具有良好的隔震效果。

周期桁架结构设计及振动特性分析

为解决船舶动力系统低频振动噪声问题,本文基于声子晶体局域共振理论,设计了一种带周期振子桁架式浮筏结构。利用有限元法和Bloch理论,分析了周期振子桁架产生带隙的原因,讨论了振子质量、安装形式和桁架结构参数对带隙特性的影响规律,设计了周期振子桁架振动特性试验,探究了桁架结构振动传递特性。结果表明:振子质量越大,带隙宽度增加,胞元尺寸越大,带隙带宽减小;振子排列方式对带隙特性影响较小,增加振子数量,宽带特性显著;采用振子间隔安装方式,相较全安装方式,带隙特性变化较小,可有效减少振子数量。

双电机推进轴系隔振方案及传递特性研究

目前对大型水面舰船电力推进装置进行隔振处理的还比较少见。为研究某大型舰船双电机推进轴系在螺旋桨激励下的传递特性和隔振方案,提出一种考虑轴承阻尼作用的有限元混合模型建立方法,给出6种隔振方案,利用Ansys软件对整个轴系进行模态和谐响应分析计算。以平均振级落差作为评价标准,验证方案的可行性。结果表明:激励力频率比系统的固有频率大√2倍时,在一定范围内,总静刚度越小隔振性能越强;在总静刚度相等的情况下,采用单个静刚度更大、数量更少的隔振器可以达到几乎相同的隔振效果;该轴系优势模态的变形集中在机组轴向前后两端的位置,增加该位置的隔振器数量可以提高隔振性能。

新型动力设备隔振减震器力学性能研究

隔振器可有效降低动力设备工作产生的高频振动,但低频地震下设备隔振器位移响应较大。将碟形弹簧和环形摩擦套筒分别作为竖向隔振和耗能单元,竖向耗能单元内设置振动间隙实现正常使用隔振和地震时减震的两阶段机制,形成一种新型动力设备隔振减震器。基于理论分析给出了隔振减震器的设计流程,并进行了算例设计,采用ABAQUS软件进行了隔振减震器的静力性能分析和动力设备整体系统的动力性能分析。结果表明:提出的隔振减震器及其系统的数值模拟与理论计算结果吻合较好;设计算例实现了设备正常工作时仅隔振、地震作用下耗能单元启动的两阶段隔振减震机制;竖向耗能单元使得设备竖向地震位移响应减小超过50%,水平向耗能单元使隔振减震器水平地震剪力减小超过80%,降低了隔振减震器地震倾覆和破坏的风险。

《基于保持建筑正常使用功能的抗震技术导则》(RISN⁃TG046-2023)解读

《建设工程抗震管理条例》自2021年9月1日起施行,对位于高烈度设防地区、地震重点监视防御区的新建学校、幼儿园、医院、养老机构、儿童福利机构、应急指挥中心、应急避难场所、广播电视等建筑的抗震性能提出了更高要求,即:要求由“保证安全性”提升到“保持正常使用功能”。因此,住房和城乡建设部标准定额研究所于2023年5月12日颁布了《基于保持建筑正常使用功能的抗震技术导则》(RISN-TG046—2023)。为了帮助使用者更深入地理解《导则》,对《导则》的编制背景、编制过程以及各章节内容进行简要介绍,对《导则》的关键条文进行深入解读,详细说明了震时正常使用建筑的设计流程。《导则》创新提出了通过位移、加速度双控实现结构、非结构、设备三保护的设计理念,为实现建筑震时正常使用提供了科学实用的解决方案。