Stability of mine ventilation system based on multiple regression analysis

In order to overcome the disadvantages of diagonal connection structures that are complex and for which it is difficult to derive the discriminant of the airflow directions of airways, we have applied a multiple regression method to analyze the effect, of changing the rules of mine airflows, on the stability of a mine ventilation system. The amount of air （ Qj ） is determined for the major airway and an optimum regression equation was derived for Qi as a function of the independent variable （ Ri ）, i.e., the venti- lation resistance between different airways. Therefore, corresponding countermeasures are proposed according to the changes in airflows. The calculated results agree very well with our practical situation, indicating that multiple regression analysis is simple, quick and practical and is therefore an effective method to analyze the stability of mine ventilation systems.

Sensitivity analysis of relevant parameters in complicated mine ventilation network by numerical test

Depending on the numerical test approach on a computer, the relationships among relevant parameters, eg branch number, node number, mesh number, computation accuracy, preliminary value of airflow rate, iteration number, computation time and convergence in a mine ventilation network analysis, were investigated based on 5 mine ventilation systems. The results show that a higher computation accuracy greatly influences the iteration number. When the accuracy reaches 10-6m3·s-1 for solving a complicated mine ventilation network, the running time is too long though a high-speed computer is used. The preliminary value of airflow rate in the range of 1100m3·s-1 has little effects the iteration number. The structure of network also has some effect on the iteration number.

Applied analysis of ventilation technology in residential buildings in Changjiang river valley

Making the use of ventilation technology may decrease building energy consumption,improve indoor thermal environment,and ameliorate indoor air quality. Combining with the meteorological characteristics in the Changjiang river valley and focusing on Chongqing,this work makes an applied analysis of the feasibility of intermittent mechanical ventilation. By comparison of various ventilation modes,it gives a summary of the suitable ventilation ways for different weather conditions with the combination of testing data and experimental data.

Correlation analysis of five factors influencing minute volume during high frequency jet ventilation on lung modal: a laboratory study

Five factors influencing minute volume during high frequency jet ventilation were studied on lung modal by stepwise regression analysis. Among these factors, driving pressure is of the greatest dominance. Others are inspiratory and expiratory time ratio, tube diameter, frequency of ventilation and needle distanee, in the order of their impact. A formula was also developed for predicting the parameters.The result is quite satisfactory.

The research analysis and application of stability of ventilation system

The stability of ventilation system includes stabilities of branch, network and main fan. The ventilation system is a dynamic process. The parameters in the ventilation system vary with time. In the paper, a group of mathematical models of quantitative analysis are set up, and the mathematical models are suitable to any ventilation system.

Increasing Ventilation by Passive Strategies: Analysis of Indoor Air Circulation Changes through the Utilization of Microclimate Elements

A demand for renewable alternatives that would be able to deal with the problems related to well-being is directly linked to the world’s growing needs to save energy and reduce environmental costs. For a project implementation addressing these issues, it is essential to know the climatic conditions of the target area. Taking natural ventilation, climatic factors, and renewable alternatives as important sources of comfort, in this work, passive strategies, through the utilization of microclimate elements as well as the location of outside obstacles, were imposed on an initial and specific project. The objective was to introduce obstacles which could interfere in the field of external wind and evaluate whether this outside intervention is able to make changes in indoor air circulation. The wind fields for the studied cases were obtained by computational simulations, and their consequences were analyzed to attain thermal comfort. The method adopted to obtain the wind fields was a Petrov-Galerkin type method, which is a stabilized mixed finite element method of the Navier-Stokes equations considering the incompressibility and formulated in primitive variables, velocity and pressure. The obtained results point to the solutions that promote the increase or decrease of the wind-field intensity.

Lung ultrasound score evaluation of the effect of pressure-controlled ventilation volume-guaranteed on patients undergoing laparoscopicassisted radical gastrectomy

BACKGROUND Laparoscopic-assisted radical gastrectomy(LARG)is the standard treatment for early-stage gastric carcinoma(GC).However,the negative impact of this proce-dure on respiratory function requires the optimized intraoperative management of patients in terms of ventilation.AIM To investigate the influence of pressure-controlled ventilation volume-guaranteed(PCV-VG)and volume-controlled ventilation(VCV)on blood gas analysis and pulmonary ventilation in patients undergoing LARG for GC based on the lung ultrasound score(LUS).METHODS The study included 103 patients with GC undergoing LARG from May 2020 to May 2023,with 52 cases undergoing PCV-VG(research group)and 51 cases undergoing VCV(control group).LUS were recorded at the time of entering the operating room(T0),20 minutes after anesthesia with endotracheal intubation(T1),30 minutes after artificial pneumoperitoneum(PP)establishment(T2),and 15 minutes after endotracheal tube removal(T5).For blood gas analysis,arterial partial pressure of oxygen(PaO_(2))and partial pressure of carbon dioxide(PaCO_(2))were observed.Peak airway pressure(P_(peak)),plateau pressure(Pplat),mean airway pressure(P_(mean)),and dynamic pulmonary compliance(C_(dyn))were recorded at T1 and T2,1 hour after PP establishment(T3),and at the end of the operation(T4).Postoperative pulmonary complications(PPCs)were recorded.Pre-and postoperative serum interleukin(IL)-1β,IL-6,and tumor necrosis factor-α(TNF-α)were measured by enzyme-linked immunosorbent assay.RESULTS Compared with those at T0,the whole,anterior,lateral,posterior,upper,lower,left,and right lung LUS of the research group were significantly reduced at T1,T2,and T5;in the control group,the LUS of the whole and partial lung regions(posterior,lower,and right lung)decreased significantly at T2,while at T5,the LUS of the whole and some regions(lateral,lower,and left lung)increased significantly.In comparison with the control group,the whole and regional LUS of the research group were reduced at T1,T2,and T5,with an increase in PaO_(2),decrease in PaCO_(2),reduction in P_(peak) at T1 to T4,increase in P_(mean) and C_(dyn),and decrease in Pplat at T4,all significant.The research group showed a significantly lower incidence of PPCs than the control group within 3 days postoperatively.Postoperative IL-1β,IL-6,and TNF-αsignificantly increased in both groups,with even higher levels in the control group.CONCLUSION LUS can indicate intraoperative non-uniformity and postural changes in pulmonary ventilation under PCV-VG and VCV.Under the lung protective ventilation strategy,the PCV-VG mode more significantly improved intraop-erative lung ventilation in patients undergoing LARG for GC and reduced lung injury-related cytokine production,thereby alleviating lung injury.

Subglottic Secretion Drainage for Preventing Ventilator Associated Pneumonia: A Meta-analysis

Objective： Ventilator associated pneumonia （VAP） has been shown to be associated with significant morbidity and mortality（ Chastre and Fagon, 2002; klompas, 2007） among mechanically venti- lated patients in the intensive care unit （ICU）, with the incidence ranging from 9% to 27% ; crude mortality ranges from 25% to 50%.1-3 A meta-analysis of published studies was undertaken to combine information regarding the effect of subglottic secretion drainage （SSD） on the incidence of ventilated associated pneumonia in adult ICU patients. Methods： Reports of studies on SSD were identified by searching the PUBMED, EMBASE, and COCHRANCE LIBRARY databases （December 30, 2010）. Randomized trials of SSD compared to usual care in adult mechanically ventilated ICU patients were included in this meta-analysis. Results： Ten RCTs with 2,314 patients were identified. SSD significantly reduced the incidence of VAP [ relative risk （RR） =0.52, 95% confidence interval （C/）： 0.42-0.64, P〈0.000 01]. When SSD was compared with the control groups, the overall RR for ICU mortality was 1.00 （95% CI, 0.84-1.19） and for hospital mortality was 0.95 （95% CI, 0. 80-1.13）. Overall, the subglottic drainage effect on the days of mechanical ventilation was -1.52 days （95% CI, -2.94 to -0.11） and on the ICU length of stay （LOS） was -0.81days （95% CI, -2.33 to -0.7）. Conclusions： In this meta-analysis, when an endotracheal tube （ETT） with SSD was compared with an ETT without SSD, there was a highly significant reduction in the VAP rate of approxi- mately 50%. Time on mechanical ventilation （MV） and the ICU LOS may be reduced, but no reduction in ICU or hospital mortality has been observed in published trials,

Early mobilization for mechanically ventilated patients in the intensive care unit:a systematic review and meta-analysis

Background: Early mobilization(EM) is a regimen that was carried out by physiotherapists in a relatively early stage. It has been investigated by an increasing number of researchers. However, there has not been a meta-analysis concerning whether EM could benefit the clinical outcomes of critically ill patients requiring mechanical ventilation(MV). The present systematic review aims to evaluate the effect of EM compared with immobilization for mechanically ventilated patients.Methods: A computerized literature search was performed in six databases for related articles from inception to June 2017. We included randomized controlled trials and controlled clinical trials and used the Physiotherapy Evidence Database scale to assess the quality of included studies. Primary outcomes were measures of muscle function, duration of MV, and incidence of mortality.Secondary outcomes were adverse effects and length of stay(LOS) in intensive care unit(ICU) and hospital.Results: Eight trials were included; of those, only one study without standard EM reported that the intervention was invalid to improve the outcomes. The result of meta-analysis indicated that EM shortened the duration of MV; however, it had no positive effect on mortality and LOS in ICU.Conclusions: This review suggests that EM improves the muscle function and ventilation duration. Further research highlighting standard intervention and specific groups is needed.

Case Analysis of a Pump-Driven Heat Pipe Heat Recovery Ventilator in an Existing Experiment Building

The building energy consumption is an important part among the total society energy consumption,in which the energy consumption for air conditioning occupies almost 70%.The energy consumption of the air conditioning system for fresh air handling can be saved effectively when the exhaust air energy could be recovered to preheat or precool the fresh air.Considering the install locations requirements on field,the pump-driven heat pipes(PHP)were developed as heat recovery ventilators(HRVs)and used in an existing experiment building in Beijing Urban.The thermal performance of the PHP HRVs was tested in real operation time periods under winter running mode.Both the power and heat consumption of the modular air handling units with and without HRVs were monitored and obtained,as well as the hourly power and heat consumption.The energy savings of HRVs were analyzed.The results indicate that the PHP HRVs can work steadily and meet the energy recovery need well.The temperature effectiveness of the HRVs can be kept from 60%to 70%.The test total energy saving rate was 24.48%,and the average hourly heat consumption reduced by 28.54%.The daily energy consumption can be saved by 118 kWh,and the energy savings can reach to 9440 kWh for a whole winter.

Practice and analysis of recycling non-drinking water from air-condition and reverse-osmosis system into rainwater collection system

This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilization, and precipitation adjustment.The rainwater collection system in this program also adds the condensation water from the heating, ventilation and air conditioning （ HVAC） system and the concentration from the reverse-osmosis system used for watering greens and supplying waterscapes.By calculating, the quantity of the HVAC condensation water in summer is 3.48 m3/d, and the quantity of the reverse-osmosis concentrated water is 198 to 396 L/d.This method solves the water shortage caused by high evaporation in summer and low precipitation in winter.Supported by empirical monitoring data, the proposed method significantly increases the economic efficiency of the system during the summer period.

Structured Graded Lung Rehabilitation for Children with Mechanical Ventilation

Lung rehabilitation is safe and feasible,and it has positive benefits in weaning the machine as soon as possible,shortening the time of hospitalization and improving the prognosis of children with mechanical ventilation.However,at present,the traditional medical concept is deep-rooted,and doctors'understanding of early rehabilitation is inadequate.It is necessary to make in-depth exploration in the relevant guidelines and expert consensus to formulate standardized early rehabilitation diagnosis and treatment procedures and standards for mechanically ventilated children.In the paper,a structured graded lung rehabilitation program is constructed for children with mechanical ventilation to improve their respiratory function,shorten the time of mechanical ventilation and pediatric intensive care unit(PICU)hospitalization,and reduce their anxiety,based on the principal component analysis of functional pneumonia data.Scientific evaluation and dynamic monitoring ensure the safety of the implementation of the program and promote the prognosis and prognosis of the disease.The proposed lung reha-bilitation program provides a reference basis for the formulation of lung rehabilitation guidelines for children with mechanical ventilation.And It has important reference significance for clinical pulmonary rehabilitation to alleviate the concerns of clinicians and lay the foundation for the large-scale promotion of early lung rehabilitation.

Simulation-aided development of a compact local ventilation unit with the use of CFD analysis

Insufficient fresh air supply due to the increased air tightness of building envelopes after building renovations and window upgrades is a major concern of HVAC engineering today.The paper demonstrates the application of CFD simulations in the development of a compact decentralised ventilation unit with integrated heat recovery system for local ventilation of rooms,targeting this common issue.The device houses an innovative cyclically rotating recuperative heat exchanger,allowing effective condensate removal and de-icing in winter for its independent operation throughout the year.The paper introduces the ventilation unit,describes preparation of its numerical models,and conducts CFD simulation using Ansys Fluent software.The initial design of the device was improved following the findings of the numerical analysis,and the proposed adjustments were tested through follow-up CFD simulations,confirming that the desired outcomes were achieved.A separate CFD analysis was performed to assess the use of different air supply elements at the air outlet to the room,recommending the use of adjustable nozzles.A prototype ventilation unit was manufactured and the volume flow rate under different operating conditions was measured to be compared with the simulation results.The outcome of the research is a new type of compact local ventilation unit.An increase in device energy efficiency was achieved,with the aid of simulations,while maintaining its compact size.In addition to presenting the potential of using variant CFD analysis in the development of new HVAC equipment,the paper also indicates the drawbacks of using the Multiple Reference Frame(MRF)method to approximate the rotation of radial fan impellers in CFD simulations.

Vasoactive-Ventilation-Renal Score Predicts Cardiac Care Unit Length of Stay in Patients Undergoing Re-Entry Sternotomy: A Derivation Study

Background: The vasoactive-ventilation-renal (VVR) score includes pulmonary and renal dysfunctions not previously addressed by the vasoactive inotrope score (VIS) and may be a better predictor of cardiac care unit (CCU) length of stay (LOS) in patients undergoing re-entry sternotomy (defined as no earlier than 30 days after previous sternotomy) for congenital heart disease (CHD). Methods: Patients undergoing re-entry sternotomy for CHD from August 1, 2009 to June 30, 2016 were studied retrospectively. A total of 96 patients undergoing 133 re-entry procedures were identified. VVR scores were calculated on CCU admission post-procedure (at 0 hour), 24-hour, and 48-hour after admission to the CCU. The response variable was CCU LOS.? Recursive partition analysis identified variables predicting LOS. Results: 133 re-entry sternotomies in 96 patients made up the samples of the database;11 samples were removed due to incomplete data or placement on ECMO. Of the initial 25 features, 5 were removed for near zero variance and 3 categorical features were removed for non-information. Covariance analysis did not demonstrate any significant correlation amongst the remaining features. Initial recursive tree regression using ANOVA, cross validation and conditional predictive p-value (cp) = 0.01 produced 3 trees. The tree with lowest cross validation error was selected. The resulting 2 split trees with ventilator days less than 20 days and VVR score at 48 hours greater than 23 identified three CCU LOS groups with mean CCU LOS of 77.6, 55.1, and 9.5 days. Conclusions: Recursive partition analysis identified ventilator days greater than 20 days and the sub-population VVR at 48 hours as predictive of CCU LOS in patients undergoing re-entry sternotomy for CHD.

俯卧位机械通气对ARDS患者氧合及血流动力学影响的Meta分析

目的系统评价俯卧位机械通气对ARDS患者氧合及血流动力学的影响。方法计算机检索了从建库起至2023年5月的6个数据库(中国知网、万方数据知识服务平台、维普、PubMed、Web of Science、Cochrane Library),收集关于俯卧位辅助治疗进行机械通气的ARDS患者的研究,研究类型为随机对照实验和队列研究,检索语言为中文和英文。由2名护理研究生在经过培训和练习之后采用NoteExpress 3.8软件根据纳入、排除标准筛选文献,采用RevMan5.4软件进行Meta分析。结果检索并筛选后共纳入17篇文献进行Meta分析,其中随机对照实验12篇、队列研究5篇,共892例患者。Meta分析显示,与仰卧机械通气相比,俯卧机械通气对ARDS患者在中心静脉压[MD=0.11,95%CI(-0.15,0.36),P=0.41]、心率[MD=1.69,95%CI(-1.26,4.65),P=0.26]、平均动脉压[MD=0.21,95%CI(-0.22,0.64),P=0.33]等方面的影响,差异无统计学意义(P>0.05)。在动脉血氧分压[MD=16.5,95%CI(11.02,21.98),P<0.00001]、二氧化碳分压[MD=-1.68,95%CI(-2.75,-0.61),P=0.002]、氧合指数[MD=40.35,95%CI(29.44,51.26),P<0.00001]等方面的影响,差异具有统计学意义,但异质性较大,其中,关于PaCO_(2)的整体数据分析差异无统计学意义(P>0.05),去掉异质性较高的2篇文献后(P=0.002),总体的Meta分析结果(P=0.12),因此,俯卧位机械通气对ARDS患者PaCO_(2)的影响结果需谨慎对待。结论俯卧机械通气在改善患者氧合的同时不会影响患者的血流动力学。俯卧位机械通气是安全有效的,可以进一步在临床进行推广,以便更好地降低ARDS患者呼吸机相关并发症的发生率,提高患者的生存率,改善生活质量。

竹筒屋冷巷尺度对风压通风的影响及设计应用

在千百年来的发展中,各地形成了适应当地自然环境与地域气候的各类民居,这些民居采用了诸多生态策略去应对环境,它们具有很高的研究与应用价值。本研究着眼于广府传统民居--竹筒屋的冷巷生态策略,探究其风压通风的原理,分析冷巷的多种尺度,如冷巷的绝对尺度、相对尺度及其与风环境的夹角对风压通风效果的影响,并通过控制变量的研究方式,以软件模拟量化分析的方法进行验证并得出结论,从而形成冷巷设计的一些控制原则,并可以在今后的建筑设计中加以利用。

火力发电厂锅炉房通风效果的模拟分析

通过对火力发电厂锅炉房自然通风的效果进行CFD模拟,得到了锅炉房的速度场和温度场,改变自然窗进风位置的措施会影响温度场和速度场的分布,从而影响全面通风的效果。根据室内气流及温度的详细分布状况得出了优选方案,为火力发电厂锅炉房及类似高大空间的通风设计提供参考。

基于大数据技术的煤矿通风自动控制系统设计

煤矿通风系统是煤矿安全运行的关键,其主要功能是提供流动的空气,以确保工人的健康和安全,并减少可燃气体和粉尘的积聚。近年来,随着大数据技术的迅猛发展,其在煤矿通风自动控制系统中的应用也日益受到重视。大数据技术能够处理和分析大量的环境数据,从而提高通风系统的智能化和自动化水平。介绍了煤矿通风自动控制系统的具体设计,包括通风自动控制系统的架构设计、基于大数据技术的煤矿环境数据分析以及通风自动控制策略的实现,并对系统进行了全面的测试,验证了其有效性和实用性。

A NUMERICAL ANALYSIS OF THE VENTILATION PERFORMANCE FOR DIFFERENT VENTILATION STRATEGIES IN A SUBWAY TUNNEL

An unsteady three-dimensional analysis of the ventilation performance is carried out for different ventilation strategies to find out a ventilation method with a high performance in a subway tunnel.The natural ventilation performance associated with a train-induced air flow in a subway tunnel is examined.The dynamic layering method is used to consider the moving boundary of a train in the current CFD method.The geometries of the modeled tunnel and the subway train are partially based on those of the Seoul subway.The effects of the structure of the ventilation duct and the geometry of the partitions on the ventilation performance are evaluated.The results show that the combined ventilation ducts （to be designed）,and the partitioning blocks installed along the middle of tunnel （already in existences） are helpful for air exchange.This study can provide some guidance for the design of ventilation ducts in a subway system.

基于HACCP与目标导向多维护理在重症肺炎机械通气患者中的应用

目的观察基于危害分析及关键控制点(HACCP)与目标导向多维护理在重症肺炎机械通气患者中的应用效果。方法选择2020年1月至2023年1月就诊于新沂市人民医院的重症肺炎机械通气患者80例为研究对象,以随机数字表法将其划归为40例观察组、40例对照组。对照组遵循重症肺炎机械通气常规式护理法施行护理,观察组于此基础上加用基于HACCP与目标导向多维护理,对2组干预后肺部感染评分(CPIS)、营养风险筛查表(NRS)评分、急性生理与慢性健康评分(APACHEⅡ评分)、机械通气时间、住院时间等进行比较。结果护理后,观察组重症肺炎机械通气患者CPIS评分、NRS评分、APACHEⅡ评分[(5.43±0.55)、(3.23±0.58)、(23.85±1.21)/(2.90±0.50)分]低于对照组[(6.35±0.48)、(4.33±0.47)、(25.16±0.60)/(3.95±0.60)分],机械通气时间、住院时间[(8.25±0.74)、(23.70±1.32)d]短于对照组[(10.85±0.83)、(32.03±1.27)d],差异均有统计学意义(P<0.05)。结论基于HACCP与目标导向多维护理对重症肺炎机械通气患者施加干预,利于其肺部感染、营养健康状态的改善,实现快速康复目标。