Dimensionless Study on Secretion Clearance of a Pressure Controlled Mechanical Ventilation System with Double Lungs

A pressure controlled mechanical ventilator with an automatic secretion clearance function can improve secretion clearance safely and efficiently.Studies on secretion clearance by pressure controlled systems show that these are suited for clinical applications.However,these studies are based on a single lung electric model and neglect the coupling between the two lungs.The research methods applied are too complex for the analysis of a multi-parameter system.In order to understand the functioning of the human respiratory system,this paper develops a dimensionless mathematical model of doublelung mechanical ventilation system with a secretion clearance function.An experiment is designed to verify the mathematical model through comparison of dimensionless experimental data and dimensionless simulation data.Finally,the coupling between the two lungs is studied,and an orthogonal experiment designed to identify the impact of each parameter on the system.

Double U-Shaped Slots Loaded Stacked Patch Antenna for Multiband Operation

The design of a seven-band stacked patch antenna for the C, X and Ku band is presented. The antenna consists of an H-slot loaded fed patch, stacked with dual U-slot loaded rectangular patch to generate the seven frequency bands. The total size of the antenna is 39.25 × 29.25 mm2. The multiband stacked patch antenna is studied and designed using IE3D simulator. For verification of simulation results, the antenna is analyzed by circuit theory concept. The simulated return loss, radiation pattern and gain are presented. Simulated results show that the antenna can be designed to cover the frequency bands from (4.24 GHz to 4.50 GHz, 5.02 GHz to 5.25 GHz) in C-band application, (7.84 GHz to 8.23 GHz) in X-band and (12.16 GHz to 12.35 GHz, 14.25 GHz to 14.76 GHz, 15.25 GHz to 15.51 GHz, 17.52 GHz to 17.86 GHz) in Ku band applications. The bandwidths of each band of the proposed antenna are 5.9%, 4.5%, 4.83%, 2.36%, 3.53%, 1.68% and 1.91%. Similarly the gains of the proposed band are 2.80 dBi, 4.39 dBi, 4.54 dBi, 10.26 dBi, 8.36 dBi and 9.91 dBi, respectively.

Alternative ventilation strategies in U.S.offices:Comprehensive assessment and sensitivity analysis of energy saving potential

Mature technologies exist to reduce the heating,ventilation,and air-conditioning(HVAC) energy associated with ventilation and use ventilation proactively to save energy.This study investigated the energy use impacts in U.S.office buildings of multiple alternative ventilation strategies that combined:economizing,demand controlled ventilation(DCV),supply air temperature reset(SR),and/or a doubled ventilation rate.We used energy simulations in a Monte Carlo analysis,sampling 17 building inputs and varying locations to match the climate zone distribution of the U.S.office stock.Results indicated the possibility for significant savings compared to a baseline that ventilated constantly at a minimum rate in both a small office type with a constant air volume(CAV) HVAC system and a medium office type with a variable air volume(VAV) system.In 95%of instances,HVAC source energy savings were 5-25%in the small-CAV office(median:11%) and 6-42%in the medium-VAV office(median:27%).In the small-CAV office,DCV typically saved the most energy,usually from heating,and heating degree days and occupant density were decisive influences.In the medium-VAV office,economizing and SR were most important,DCV usually only had minor impacts,and zone temperature setpoints,along with climate indicators,were the critical influences.Other than infiltration,envelope characteristics did not strongly influence energy impacts.The untapped primary energy savings of alternative ventilation strategies over the 74%of U.S.office floorspace reasonably represented by our modeling was estimated at 36 TWh per year,with an annual value of U.S.$ 1.25 billion.

Independent lung ventilation: Implementation strategies and review of literature

Independent lung ventilation,though infrequently used in the critical care setting,has been reported as a rescue strategy for patients in respiratory failure resulting from severe unilateral lung pathology.This involves isolating and ventilating the right and left lung differently,using separate ventilators.Here,we describe our experience with independent lung ventilation in a patient with unilateral diffuse alveolar hemorrhage,who presented with severe hypoxemic respiratory failure despite maximal ventilatory support.Conventional ventilation in this scenario leads to preferential distribution of tidal volume to the nondiseased lung causing over distension and inadvertent volume trauma.Since each lung has a different compliance and respiratory mechanics,instituting separate ventilation strategies to each lung could potentially minimize lung injury.Based on review of literature,we provide a detailed description of indications and procedures for establishing independent lung ventilation,and also provide an algorithm for management and weaning a patient from independent lung ventilation.

A Comparison of Arterial Oxygenation between 60% O2 CPAP and 100% O2 CPAP during One-Lung Ventilation: A Prospective Randomized Controlled Study

Background: One-lung ventilation (OLV) is generally adopted for thoracic surgery. The systemic application of a high fraction of inspiratory oxygen (F1O2) and continuous positive airway pressure (CPAP) to the non-ventilated lung is useful for preventing arterial oxygen desaturation. The adverse effects of elevated F1O2 include oxidative lung injury, resorption atelectasis and coronary and peripheral vasoconstriction. It is preferable to avoid hyperoxemia in patients with complications such as chronic obstructive pulmonary disease, idiopathic pneumonia, and bleomycin-treated lungs. We aimed to determine whether the application of 60% O2 CPAP to the non-ventilated lung is sufficient to provide adequate oxygenation with 60% O2 to the ventilated lung. Methods: A total of 70 patients scheduled to receive elective thoracic surgery requiring OLV were recruited. Left double-lumen tubes were applicable in all surgeries. Patients were randomly allocated to one of two groups, to receive either 60% O2 CPAP (60% CPAP group, n = 35), or 100% O2 CPAP (100% CPAP group, n = 35) at a setting of 2 - 3 cmH2O, applied to the non-ventilated lung. Arterial blood gas analyses were obtained at the following stages: RA, spontaneous breathing under room air (RA);TLV, during total lung ventilation (TLV) prior to the initiation of OLV;T5, 5 min after the initiation of OLV;T15, 15 min after the initiation of OLV;T30, 30 min after the initiation of OLV. Results: The PaO2 value in 60% CPAP group vs. 100% CPAP group at each measurement were as follows: RA (mean [standard deviation: SD], 89.7 [8.2] mmHg vs. 85.8 [11.9] mmHg);TLV (277.9 [52.9] mmHg vs. 269.2 [44.0] mmHg);T5 (191.4 [67.9] mmHg vs. 192.3 [66.0] mmHg);T15 (143.2 [67.3] mmHg vs. 154.7 [60.8] mmHg) and T30 (95.6 [32.0] mmHg vs. 112.5 [36.5] mmHg), respectively. Among the five measurement points, T30 was the only time point at which the 100% CPAP group showed a significantly greater PaO2 value than the 60% CPAP group (p = 0.0495). The SaO2 at T30 in the 100% CPAP group (97.4 [2.0]%) was also significantly greater than that in the 60% CPAP group (96.3 [2.2]%, p = 0.039). No differences were found between the groups regarding changes to the overall PaO2 values (p = 0.44) and SaO2 values (p = 0.23) during the study period. Conclusions: Oxygenation could be safely maintained in relatively healthy patients with 60% O2 OLV and 60% O2 CPAP. The application of 60% O2 CPAP during OLV for patients who are not suited to exposure to high F1O2 may be an alternative form of respiratory management.

Double perovskite anti-supported rare earth oxide catalyst CeO_(2)/La_(2)CoFeO_(6)for efficient ventilation air methane combustion

Ventilation air methane is one of available resources with a massive reserve.However,most of ventilation air methane is discharged into the air and pollutes the environment.Catalysts with high temperature resistance(>800℃)for ventilation air methane are very essential for utilization of the ventilation air methane.We mainly prepared catalysts CeO_(2)/La_(2)CoFeO_(6)and La_(2)CoFeO_(6)/CeO_(2)and comparative samples CeO_(2)and La_(2)CoFeO_(6)by the simple sol-gel method and calcined them under 9000C,and tested the catalytic performance of ventilation air methane combustion under the condition of 5 vol%H_(2)O.The experimental results show that the light-off temperature(T_(1O))and complete combustion temperature(T_(90))of the ventilation air methane combustion reaction of CeO_(2)/La_(2)CoFeO_(6)catalyst are 417.4 and 587.7℃,respectively.T_(1O)and Tgo of La_(2)CoFeO_(6)/CeO_(2)only reach 425.5 and 615.8℃.The T_(10)and T_(9O)of CeO_(2)/La_(2)CoFeO_(6)are 417.4 and 587.7℃,which are lower than those of La_(2)CoFeO_(6)[T_(10)=452.4℃and T_(90)=673.0℃)and La_(2)CoFeO_(6)/CeO_(2)(T_(10)=425.5℃and T_(90)=615.8℃).Therefore,the catalytic performance of the anti-supported rare earth oxide catalyst CeO_(2)/La_(2)CoFeO_(6)is better than that of La_(2)CoFeO_(6)and supported catalyst La_(2)CoFeO_(6)/CeO_(2).

Patient–ventilator asynchrony in Saudi Arabia: Where we stand?

Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of patient–ventilator asynchrony and how to step ahead for better patients'ventilation management.

双层浅圆仓不同入风温度的粮堆温度场分析

建立半地下双层浅圆仓的数值模型,并对机械通风不同入风温度的粮堆温度场进行数值分析,研究在机械通风过程中半地下双层浅圆仓粮堆温度场的变化规律。结果表明:当吨粮通风量为8 m^(3)/h时,平均降温速度随入风温度降低而加快,整体粮堆的平均温度从初始30℃下降至20℃。当入风温度分别为17、15、13、11℃时,地上层通风时间分别需173、148、121、111 h,地下层通风时间分别需237、196、168、142 h。当通风稳定后,地上层粮堆平均温度分别为17.02、15.01、13.14、11.14℃,地下层粮堆平均温度分别为17.51、15.83、14.04、11.25℃,均趋近于入风温度,表明机械通风可有效降低粮堆温度,保证粮食安全。

公铁合建双层盾构隧道设计关键技术

为解决公铁合建双层盾构隧道面临的总体布置、结构设计、汽车与地铁车辆联合振动以及通风排烟等技术难题,以武汉长江公铁隧道和济南黄河济泺路隧道工程实践为基础,采用方案综合比选、2.5维数值计算等方法,对公铁合建双层盾构隧道设计关键技术进行系统研究。结果表明:1)通过对隧道平面、纵断面和横断面的合理优化布置,并在废水泵房段、疏散楼梯段采取特殊布置方案,可减少公铁合建盾构隧道地下空间占用,并提高断面利用率,减小盾构隧道外径;2)采用半预制半现浇的管片+非封闭内衬结构型式,能充分发挥内部结构与管片衬砌的联合承载作用,显著减小河床冲淤作用;3)汽车与地铁联合振动作用对隧道影响较小,隧道基底饱和粉细砂地层不会发生液化;4)地铁隧道采用分段纵向烟道,可解决地铁长大区间无风井条件下的排烟难题,同时提高疏散便捷性,并大幅降低建设难度;5)公铁合建隧道在运营管理上不可避免地会出现交叉和影响,建议在管理界面划分和投资分劈上提前研究,便于决策。

通风隔热屋顶的设计策略研究

通风屋顶是一种构造简单、适用性广泛的建筑隔热构造。本文基于通风屋顶的隔热原理,分析面层架空和双层屋顶两种构建通风屋顶的基本策略和构造特征,讨论其在设计实践中的具体应用,进而以通风层的气流强化为目标,通过数值模拟解析利用热压强化的拔风构造设计和利用风压强化的风腔形态设计,为通风屋顶的性能化设计提供参考。

改良预先单肺通气加快胸腔镜手术肺萎陷的效果及安全性评价

目的评价改良预先单肺通气(OLV)在胸腔镜手术中加快术侧肺萎陷的效果及安全性。方法将2019年5月至2021年10月甘肃省肿瘤医院择期行肺楔形切除、肺叶切除术102例病人,按随机数字表法分配至常规OLV(C组)、预先OLV(P组)、改良预先OLV组(M组),每组34例。分别采用相应肺萎陷方法监测并记录病人胸腔开放后获得满意肺萎陷所需时间,胸腔开放后1、5、10、20、30 min肺萎陷评分,诱导前(T_(0))、插管后/膨肺前(T_(1))、侧卧前/膨肺末(T_(2))、侧卧后/膨肺后1 min(T_(3))、胸腔开放即刻(T_(4))、获得满意肺萎陷时刻(T_(5))的平均动脉压(MAP)、心率,T_(0)、T_(3)、T_(4)、T_(5)的脉搏血氧饱和度(SpO_(2))、动脉血氧分压(PaO_(2))、动脉血二氧化碳分压(PaCO_(2)),以及病人术中低氧血症发生、血管活性药物使用、术后肺部并发症及住院天数等情况。结果排除1例困难插管及7例胸腔粘连病人,最终94例病人研究数据被纳入分析。与C组[(14.8±2.8)min]及P组[(9.3±1.6)min]相比,M组[(6.8±1.3)min]病人胸腔开放后获得满意肺塌陷时间更短(均P<0.01);胸腔开放后1、5、10 min肺萎陷评分更高(均P<0.01)。M组病人各时间SpO_(2)、PaO_(2)、PaCO_(2)与P组相比差异无统计学意义(均P>0.05)。M组病人T_(2) MAP、心率较T_(1)、T_(3)短暂降低(均P<0.05)。三组病人无术中低氧血症发生;术中血管活性药物使用率、术后肺部并发症发生率、重症监护病房(ICU)转入率及术后住院天数组间比较均差异无统计学意义(均P>0.05)。结论改良预先OLV能更明显地加快胸腔镜手术双腔插管病人术侧肺萎陷,且对病人安全没有明显影响。

双开口谐振环结构的通风隔声性能研究

设计一种基于双开口谐振环结构的新型声屏障,采用有限元法进行分析计算,获得该模型的隔声量曲线图,计算结果表明,该结构有两个隔声峰值,通过对峰值处的声压、声压级以及声速图的分析,揭示这一现象的本质特征,研究发现所提出结构的性能是由于亥姆霍兹谐振器与法布里-珀罗谐振管共同作用而导致的,并通过实验进行对比验证。同时采用有限元法模拟研究结构参数对隔声峰值的影响,结果表明通过改变两开口圆环间的夹角以及开口宽度大小等结构参数可以调整隔声峰值。该结构的声屏障在中低频段内具有良好的通风降噪性能,可为城市交通噪声的研究提供有效方法,具有潜在的应用价值。

胸科手术中单肺通气肺萎陷技术的应用进展

相较于传统的开胸手术,胸腔镜手术(video-assisted thoracoscopic surgery,VATS)在手术视野范围较小、操作空间较窄的情况下进行,为了成功进行VATS手术,需要最大程度地优化肺隔离和肺萎陷的质量,延迟肺萎陷的麻醉技术可能阻碍胸外科手术。为了提高肺萎陷的速度和质量,临床上采取了诸多措施。该文就胸外科手术中单肺通气肺萎陷技术的应用和进展进行综述。

双风井双盘区煤矿通风系统角联分支辨识与控制

针对凉水井煤矿二水平开采通风系统中出现的角联分支问题,采用网络解算方法得到无角联微风巷道的矿井通风方案。明确了角联分支在矿井通风网络中是普遍存在、不可避免的,角联微风分支是管控重点。提出了两种通风系统布置方案,通过网络解算得到各自的通风效果。方案一中新风从盘区大巷两端进入,盘区大巷的中间段出现了角联微风段,对应的解决方案要增加用风量与井巷工程量。优选出的第二方案利用上水平盘区大巷将二号进风井与另一组进风井的新风从盘区大巷的同一端引入盘区,避免了角联微风分支的形成。研究结果为凉水井煤矿二水平安全开采提供了技术支撑。

3车道瓦斯隧道通风流场及瓦斯运移规律研究

为有效进行大断面公路瓦斯隧道施工期通风降气,以古金高速公路大梁子隧道工程为依托,采用SCDM软件建立2台阶带仰拱的计算模型,使用Fluent软件进行数值模拟,揭示在不同台阶长度、风筒出风口距掌子面距离、双风筒布设形式下,隧道掌子面及附近区域的通风流场特征和瓦斯运移规律,并结合现场监测数据进行验证。研究结果表明:1)流场在通风20 min后基本稳定,上台阶和仰拱段会形成涡流阻碍瓦斯的运移、扩散和稀释,在风筒非对称布设情况下,掌子面风筒对侧的墙角处出现瓦斯积聚现象;2)隧道内通风降气效果的敏感性影响因素排序为双风筒及布设形式>风筒出风口距掌子面距离>台阶长度,建议优先采用双风筒同侧布设送风,其次调整风筒出风口距掌子面距离为20~25 m和台阶长度为15~20 m;3)采用双风筒同侧布设通风时,掌子面及附近区域风速提高、瓦斯体积分数大幅降低,且施工现场开展的送风试验与数值计算结果吻合度高,验证了双风筒同侧送风的可靠性。

支气管封堵器与双腔支气管导管用于单肺通气肺塌陷的效果比较

目的比较支气管封堵器(BB)与双腔支气管导管(DLT)用于单肺通气(OLV)肺塌陷的效果,旨在为临床应用提供参考。方法选择2020年10月至2022年9月于我院择期行胸腔镜下右肺叶切除术的40例患者为研究对象,按肺塌陷方式不同将其分为BB组和DLT组,每组20例,BB组和DLT组中分别有2、1例发生低氧血症,改为双肺通气,剔除研究,最终BB组18例、DLT组19例完成研究。BB组将BB用于OLV肺塌陷,DLT组将DLT用于OLV肺塌陷。比较两组的应用效果。结果两组的肺塌陷评分(LCS)比较,差异无统计学意义(P>0.05)。侧卧位即刻(T_(1))~开胸后5 min(T_(4)),两组的平均动脉压(MAP)、心率(HR)、血氧饱和度(SpO_(2))及动脉血氧分压(PaO_(2))比较,差异无统计学意义(P>0.05);BB组和DLT组分别有2例和3例患者发生SpO_(2)下降,但均未出现低氧血症。BB组和DLT组开胸时肺塌陷均较优,术侧肺完全萎陷,手术视野暴露满意。结论BB可有效完成开胸前肺塌陷,对开胸前肺塌陷的影响及OLV效果与DLT相当,可将其推广应用于临床当中。

基于通风与火灾分析的办公建筑双层玻璃幕墙挑檐研究

随着办公建筑的快速发展,双层玻璃幕墙(double skin facade,DSF)这种新型的围护结构得到了广泛的应用,但其防火与通风性能的问题也日益凸显。因此,本研究使用Fluent和Pyrosim软件对双层玻璃幕墙进行实验分析,探究防火挑檐对烟气和通风二者的影响。结果表明,对于竖向空腔高度为三层的多楼层双层玻璃幕墙建筑而言,在防火方面挑檐宽度越宽其防火效果越好,而在通风方面挑檐宽度越小其通风率越高。因此,空腔宽度为2 m的双层玻璃幕墙办公建筑,当挑檐宽度为1.5 m时,其防火性能最优;当挑檐宽度为1 m时,同时兼顾防火与通风性能;当不设置挑檐,采用防火封堵装置时,其通风性能最优。

双主风机联合运转通风系统优化研究

【目的】为解决平煤九矿双主风机联合运转通风系统在开采后期存在的丁组风机风量富裕、己组风机负担载荷过大的问题,需要对双主风机联合运转下的矿井通风系统进行优化。【方法】采用数值模拟的方法,构建平煤九矿中长时期的通风Ventsim三维可视化模型,提出相关优化方案,对不同方案从通风效果和技术经济等方面进行对比分析。【结果】研究结果表明,通过扩修己二东翼回风下山、己二回风下山和己组总回风等高阻力段巷道断面至16 m^(2),新建回风联巷沟通己二回风下山和丁组回风下山,调节丁组风机角度至-14°,使丁组风机担负己二东翼回风风量,己组风机担负己二西翼回风风量,有效降低了矿井的通风阻力,实现按需分配,满足各用风地点风量的要求,己组和丁组风机负担的风量和风压更加合理。【结论】优化方案有效解决了该矿井中存在的问题,提高了矿井通风系统的信息化管理水平。

寒冷地区自然通风型光伏双层皮幕墙全年节能特性研究

针对寒冷地区普通双层中空玻璃幕墙、自然通风型透明双层皮幕墙(CG-DSF)和半透明光伏双层皮幕墙(PV-DSF)进行了全年建筑能耗分析,利用Energyplus软件对建筑供冷、供热、照明能耗及光伏产能情况进行模拟,并分析了新型PV-DSF幕墙结构的节能潜力.首先通过实验测量结果验证了传热模型、通风模型、发电模型和光照模型的可靠性;然后利用双层幕墙自然通风的功能,分别设定合理的通风模式进行全年能耗模拟.结果表明,相比于普通中空玻璃幕墙,CG-DSF及PV-DSF均可以降低建筑全年的空调能耗,其空调能耗分别为普通中空玻璃幕墙的60%和52%左右.耦合碲化镉半透明光伏玻璃的PV-DSF夏季供冷能耗显著降低,其年光伏发电量约为50.68 kW·h/m^(2),虽然其供热和照明能耗有所增加,但其全年总净能耗最低,比普通中空玻璃幕墙降低了46%,表现出优异的建筑节能潜力.

基于反向漏风的地铁区间隧道并联通风机运行调节优化

为明确隧道运营期间并联通风机的调节依据,依托青岛地铁八号线大洋站至青岛北站区间隧道,搭建隧道通风系统模型。通过并联试验,测定了通风机变频频率、电功消耗值及相应风量,并以功率差值占比、通风效率为依据,探究并联通风机的反向漏风规律和最佳频率匹配范围。结果表明:由于管网结构的影响,并联通风机反向漏风存在抑制临界点;为避免反向漏风,并联通风机变频调速处于额定转速的30%~50%、>50%~70%、>70%~90%时,其功率差值占比不宜大于1.6%、6.1%、17.6%;并联通风机同型号同频率运行时,通风效率不一定最优,要使并联通风机增效减耗运行,风机变频调速宜处于额定转速的70%~90%且功率差值占比≤6%。频率匹配范围的确定可为隧道运营期间并联通风机的变频调节提供参考。