Effects of oxygen concentration and flow rate on cognitive ability and physiological responses in the elderly

The supply of highly concentrated oxygen positively affects cognitive processing in normal young adults. However, there have been few reports on changes in cognitive ability in elderly subjects following highly concentrated oxygen administration. This study investigated changes in cognitive ability, blood oxygen saturation （%）, and heart rate （beats/min） in normal elderly subjects at three different levels of oxygen [21% （1 L/min）, 93% （1 L/min）, and 93% （5 L/min）] administered during a 1-back task. Eight elderly male （75.3 ＋ 4.3 years old） and 10 female （71.1 ＋ 3.9 years old） subjects, who were normal in cognitive ability as shown by a score of more than 24 points in the Mini-Mental State Examination-Korea, participated in the experiment. The experiment consisted of an adaptation phase after the start of oxygen administration （3 minutes）, a control phase to obtain stable baseline measurements of heart rate and blood oxygen saturation before the task （2 minutes） and a task phase during which the 1-back task was performed （2 minutes）. Three levels of oxygen were administered throughout the three phases （7 minutes）. Blood oxygen saturation and heart rate were measured during each phase. Our results show that blood oxygen saturation increased, heart rate decreased, and response time in the 1-back task decreased as the concentration and amount of administered oxygen increased. This shows that administration of sufficient oxygen for optimal cognitive functioning increases blood oxygen saturation and decreases heart rate.

Large Eddy Simulation of the Particle Coagulation in High Concentration Particle-Laden Planar Jet Flow

Particle coagulation by Brownian motion is an important but difficult research topic.When particle volume concentration is larger than 0.1%,the classic SMOLUCHOWSKI equation is not applicative anymore.The high concentration coagulation,with HEINE＇s correction,source terms for the Taylor-series expansion method of moments（TEMOM） are firstly driven in this paper.Ultra-fine particle（d0？100 mm） with initial volume fraction f？1% coagulation in a planar jet turbulence flow is simulated via the large eddy simulation（LES）.The instantaneous and time-averaged particle distributions and the high concentration enhancement are given out.The particle number concentration distribution results show that the coagulation is more intense comparing to dilute case in previous research,especially near the nozzle exit.After jet flow is fully developed,the effect is much more obvious at the region between vortexes.The time-averaged γ（the high concentration enhance factor） distributes sharply and symmetrically about the jet centerline at the upstream,but becomes broad and flat at downstream where the cross-stream averaged γ fluctuates drastically.As a new attempt,this paper shows Brownian coagulation with high concentration also can be calculated via TEMOM appropriately,and the coagulation at the region between vortexes is about 1.38 times intensive of the dilute result calculated by the classic Smoluchowski theory.

Diffusion Process of High Concentration Spikes in a Quasi-Homogeneous Turbulent Flow

When a mass spreads in a turbulent flow, areas with obviously high concentration of the mass compared with surrounding areas are formed by organized structures of turbulence. In this study, we extract the high concentration areas and investigate their diffusion process. For this purpose, a combination of Planar Laser Induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV) techniques was employed to obtain simultaneously the two fields of the concentration of injected dye and of the velocity in a water turbulent channel flow. With focusing on a quasi-homogeneous turbulence in the channel central region, a series of PLIF and PIV images were acquired at several different downstream positions. We applied a conditional sampling technique to the PLIF images to extract the high concentration areas, or spikes, and calculated the conditional-averaged statistics of the extracted areas such as length scale, mean concentration, and turbulent diffusion coefficient. We found that the averaged length scale was constant with downstream distance from the diffusion source and was smaller than integral scale of the turbulent eddies. The spanwise distribution of the mean concentration was basically Gaussian, and the spanwise width of the spikes increased linearly with downstream distance from the diffusion source. Moreover, the turbulent diffusion coefficient was found to increase in proportion to the spanwise distance from the source. These results reveal aspects different from those of regular mass diffusion and let us conclude that the diffusion process of the spikes differs from that of regular mass diffusion.

Particle characteristics and rheological constitutive relations of high concentration red mud

Red mud has relatively small solid particles （d50= 13.02 μm） and will flow in paste form under high pressure during pipeline transport. Red mud belongs to a two-phase flow of materials with high viscosity and a high concentration of non-sedimentation, homogeneous solid-liquids. It is difficult to test its rheological properties under atmospheric pressure. Measurements such as rotational viscometry can not reflect the real state of the material when it is flowing in a pipe. Tested rheological parameters are somewhat higher than the actual values. In our investigation, grain shape, distinctive modality and grain size distribution of red mud were tested. Based on the principle of tube measurement, rheological experiments on red mud at different concentrations were carried out by using our independently developed tube-type pressure theology test facility, and obtained constitutive equations. We conclude that red mud behaves as non-Newtonian pseudo-plastic fluid in pipe flows. Its consistency and power-law indices vary considerably with different concentrations.

Effects of oxygen enriched tent by a new oxygen concentration machine on blood oxygen saturation and heart rate in tibet

Many people who live in the low altitude areas are often suffered from hypoxia when they entered the high plateau. This problem may seriously influence the physical and mental state and work efficacy for the travelers and workers. Oxygen enrichment of a small space air at high altitude is considered as a simple way to provide lowlanders enriched oxygen for sleeping and resting, improving work efficiency, so we developed an oxygen concentration machine based on the technology of oxygen enrichment membrane. This paper tested 8 healthy male lowlanders (age 21.63±1.77 yr) who have never exposed to plateau performed an incremental exercise on cycle ergometer at sea-level in order to be used as sea-level controls. Two days later, the same subjects were taken to Lhasa (3700 m) by air and exposed to the plateau, performed the same exercise as they did at sea-level. The next day, all subjects were asked to enter the experimental tent which was enriched with oxygen (higher than 24%) by the oxygen concentration machine and sleep for 10 hours at night, then exposed to plateau and performed the same exercise twice at different time (2 hours and 10 hours after oxygen enrichment). During the tests, subjects must cycled continuously at 60 rpm beginning with a 3 min exercise intensity of 0 W followed by incremental increases of 25 W every 3 min until 150 W, pulse oxygen saturation (SpO2) and heart rate (HR) were recorded. After sleeping in an oxygen enrichment of tent air, 2 hours later, the subjects’ load capacity had no difference compared with control group, but significant difference than before (higher SpO2 and lower HR), which indicated that oxygen concentration machine is effective in increasing the oxygen concentration of the air for the tent and sleeping in the oxygen enrichment tent for l0 h might be effective in improving exercise performance during high-altitude hypoxia. At the same time, 10 hours later, when work-load exceeded 125 W, the same effects were also found. The results indicated the effects of oxygen enrichment of tent air could last a certain period of time.

Experimental studies on resistance characteristics of high concentration red mud in pipeline transport

Red mud will flow in paste form under high pressure during pipeline transport.It belongs to a two-phase flow of materials with high viscosity and a high concentration of non-sedimentation,homogeneous solid-liquids.In pipeline transport,its resistance char- acteristics will be influenced by such factors as grain size,velocity,concentration,density, grain composition and pipe diameter etc..With the independently developed small-sized tube-type pressure resistance test facility,studied the resistance characteristics of red mud concerning the three influencing factors,paste concentration,velocity and pipe diameter, which attract the most attention in projects.The fine grain size of the red mud is d_(50)= 13.02μm.According to the experimental results,the pressure loss in transport will in- crease along with the increase of velocity and will fall along with the increase of pipe di- ameter.A 1% difference in paste concentration will result in a 50%～100% difference in pipeline resistance loss.These experimental data is hoped to be direct guidance to the design of high concentration and viscous material pipeline transport system.

Energy Efficiency Analysis of Oxy-Fuel Circulating Fluidized Bed Combustion System with High Oxygen Concentration

The low net efficiency of oxy-fuel circulating fluidized bed(CFB)combustion is mainly due to the addition of air separation unit(ASU)and carbon dioxide compression and purification unit(CPU).High oxygen concentration is one of the effective methods to improve the net efficiency of oxy-fuel combustion technology in CFB.In this research,a series of calculation and simulation were carried out based on Aspen Plus platform to provide valuable information for further investigation on the CFB oxy-fuel combustion system with high oxygen concentration(40%,50%).A CFB oxy-fuel combustion system model with high oxygen concentration was established including ASU,CPU and CFB oxy-fuel combustion and heat exchange unit.Based on the simulation data,energy and exergy efficiency were analyzed to obtain the following results.The cross-sectional area of furnace and tail flue of 50%CFB oxy-fuel combustion boiler are 43%and 56%of the original size respectively,reducing the construction and investment cost effectively.With the increase of oxygen concentration,the net efficiency of power generation increased significantly,reaching 24.85%and increasing by 6.09%under the condition of 50%oxy-fuel combustion.The total exergy loss increases with the increase of oxygen concentration.In addition,the exergy loss of radiation heat transfer is far higher than convection heat transfer.

浅埋深综放工作面采空区“三带”分布研究

为研究浅埋深综放工作面采空区“三带”分布规律,在串草圪旦煤矿6101综放工作面采空区埋设束管,对采空区“三带”进行了现场实测。实测结果表明:由于煤层埋深浅、地表起伏大、进风侧存在地表漏风,进风侧采空区“三带”明显滞后于回风侧,进回风两侧氧化带宽度分别为87.8 m和61.4 m。利用FLUENT软件对实测条件下该工作面采空区“三带”进行了数值模拟,模拟结果和现场实测结果基本一致。同时模拟了不漏风条件下该工作面采空区“三带”分布,此时采空区散热带、氧化带范围大幅度减小,进风侧采空区氧化带稍大,而工作面中部和回风侧“三带”分布基本一致。

自贸试验区对城市创业活跃度的影响机制分析

自贸试验区作为国家政策的重要实践基地,对于激发城市创业活力具有显著影响。本文采用2006—2019年我国280个地级市的面板数据,运用多时点双重差分方法,探究自贸试验区对城市创业活跃度的影响及其作用机制。结果表明,自贸试验区的设立能够提升城市创业活跃度,并且在Ⅰ型大城市和中小城市的提升效应显著大于Ⅱ型大城市;对中等和高度市场化水平的城市在创业活跃度方面的促进效果显著,而对低市场化水平的城市则具有一定的抑制作用。进一步的机制分析发现,自贸试验区通过促进外商直接投资流入和高端要素集聚提升城市创业活跃度。为充分发挥自贸试验区对城市创业活跃度的积极作用,后续应更加注重在不同区域实施差异化政策,持续推行市场化改革,以激发城市创业的自发性和积极性。同时,加强技术创新和人才引进工作,提升城市技术密集度和知识密集度,从而更好地推动“大众创业、万众创新”政策的落地实施。

铅精矿侧吹熔炼气-液多相流动过程数值模拟

铅精矿富氧侧吹熔池熔炼技术具备原料适用范围广、炉体使用寿命长、废热废料利用率高、热量有效利用率高等诸多特点,在炼铅工艺中占有重要地位。基于VOF多相流模型与Realizable k-ε湍流模型建立了侧吹炉内的多相湍流流动过程数值仿真模型,并利用物理模型对仿真可靠性进行了验证。模拟研究了喷枪喷气速度、喷嘴排布方式以及渣液位高度对熔池搅拌效果的影响,确定了喷枪结构不变的情况下,最佳的工艺条件为喷枪喷气速度100~150 m/s、渣液位高度1.6~1.7 m。

射流强化非填料式溶气设备的工作性能

溶气设备是溶气释放式微细气泡发生系统的重要组成部分,基于自主设计研发的射流强化非填料式溶气设备,对其在不同操作参数下的工作性能开展了实验研究。采用WTW手持式溶解氧测定仪实施全程在线带压测量,同时以空气在水中溶解氧浓度的变化率直接表征溶气性能。结果表明,新型溶气设备在低能耗下仍具有较高的溶气性能;溶气性能随气液比的增加而增加,溶气效率随着溶气压力的增加而降低,随着进水流量的增加呈现出先增加后减小的趋势,氧转移传质系数随溶气压力和进水流量的增加而增加,最佳进水流量区间为0.7~0.9m^(3)/h。由于新型溶气设备在使用普通球阀减压释气成泡时,仍能产生高质量的微细气泡,占地面积远小于传统设备且不易堵塞,因此在实际工程应用中更具优势。

注氮对采空区自燃“三带”影响的考察

针对注氮对采空区“三带”范围的影响问题,在皖北某一工作面分别进行了有/无注氮操作下的采空区温度和氧气浓度检测。基于氧气浓度指标,发现注氮操作对采空区“三带”划分范围影响不大,但是在采空区中存在明显的氮气影响区域,并依据氧气浓度基本确定了该区域范围。在实际工程中,可通过调整注氮参数,将氮气影响区域的氧气浓度降至窒息带氧气浓度,从而获得最佳的注氮操作参数。

氧气浓缩器多参数测量装置的研制

目的研发一种氧气浓缩器的气体温度、压力、流量和氧气浓度的多参数测量装置,用于监测氧气浓缩器在标准YY 9706.269—2021中电磁兼容抗扰度实验时的基本性能。方法通过对氧气浓缩器电磁兼容抗扰度实验特点的分析,研发装置结构设计成回字型,由温度传感器、压力传感器、可调节流阀、质量流量计、顺磁氧传感器、电源模块、数据采集器和数据记录软件组成,其中测量模块要求精度高、响应快、稳定性好,数据采集器要求分辨率高、采样率高,数据记录软件基于LabVIEW开发的检测应用程序。再使用标准气体、数字多用表和质量流量计等测量仪器,对研发装置进行氧气校正和准确性验证。同时根据标准YY 9706.269—2021条款202.6.2.1.10要求,选择医用分子筛制氧机作为样品进行电磁兼容抗扰度测试,使用研发装置监测样品的基本性能。结果研发装置的参数测量达到如下指标,温度的量程是0~100℃,压力的量程是0~200 kPa,流量的量程是0~15 L/min,氧气浓度的量程是0~100%;温度的准确度是±0.5℃,压力准确至所测值的±2%以内,流量准确至所测值的±2%以内,氧气浓度准确至所测值的±1%以内。结论研发装置能够准确测量氧气浓缩器的气体温度、压力、流量和氧气浓度,各个参数的测量结果以Excel文件形式保存。研发装置符合标准YY 9706.269—2021对氧气浓缩器在电磁兼容抗扰度实验的相关要求。

拉晶工艺参数对N型单晶硅氧含量的影响研究

TOPCon电池基板是以N型硅片为主,N型硅片的氧含量在一定程度上影响着TOPCon电池的转换效率。本文采用直拉法进行单晶硅的拉制,通过调整埚转、氩气流量和炉压来研究拉晶工艺参数对N型单晶硅氧含量的影响。数值模拟分析和实验结果表明:坩埚转速的增加会抑制浮力-热毛细漩涡,减少熔体界面处SiO的挥发,提高硅熔体内部和单晶硅棒氧含量;增大氩气流量和降低炉压可增大熔体界面处SiO的质量流量,有效促进SiO挥发,减少固液界面处氧含量,从而降低单晶硅棒氧含量。根据单晶硅氧含量测试和EL检测结果可知,坩埚转速5 r/min、氩气流量100 L/min和炉压1 200 Pa时拉制的N型单晶硅氧含量最低,电池端同心圆比例也是最低的。本文研究结果可为N型单晶硅棒降氧提供一定思路。

沟壑地区浅埋煤层采空区煤自燃危险区域研究

沟壑地区浅埋煤层上覆岩层厚度不均匀,采动影响造成地表开裂形成台阶式下沉趋势,造成地表裂隙漏风,长时间漏风供氧致采空区遗煤自燃氧化条件良好,威胁矿井安全生产。以典型的某矿沟壑地貌浅埋煤层中11B602工作面为研究对象,现场观测地表裂缝发育几何形貌及大尺度漏风裂缝分布特征,并采用数值模拟研究采空区漏风规律,划分煤自燃危险区域。研究表明:工作面对应地表存在拉伸型和开裂型等裂缝,且风流由地表漏向采空区;受地表漏风影响,采空区内整体O_(2)浓度升高,两巷位置O_(2)浓度大于8%,采空区内由地表向两道漏风引起的煤自燃危险区域为进风侧100~151 m、回风侧14~85 m。通过采取井上下综合防治的措施,有效控制了地表漏风和采空区遗煤自燃,保障了工作面的安全生产。

侧吹熔池熔炼炼铜生产实践

富氧侧吹炉是一种综合物料干燥、物料焙烧以及物料熔炼的炼铜生产工艺。基于富氧侧吹炼铜工艺反应机理,对比侧吹炼铜工艺与传统炼铜工艺的特点,结合江铜国兴富氧侧吹炉的生产实践,分析异常炉况产生的原因,并提出相应的处理办法,通过提高富氧浓度,不仅节省了大量的燃料,而且生产效率大大提高。

高流量弥散供氧系统的研究

目的:对高流量弥散供氧系统解决方案进行探讨,重点关注采用分子筛制氧机与罗茨风机相结合的创新技术路径。方法:通过对系统结构、工作原理、关键参数设计等多方面进行深入剖析,结合分子筛制氧机和罗茨风机两种设备,提出了一个整合性的高流量弥散供氧系统设计方案。结果:该方案能够实现快速且均匀地向大面积空间供应富氧空气。结论:该方案在实际应用中具有可行性和优越性。

电极孔径及温度对闭式氢氧燃料电池性能的影响机理研究

针对燃料电池内部复杂的水传输机制和水管理策略的影响因素,研究多孔电极的孔径对水传输和水分布情况的影响。建立燃料电池等温模型,通过改变多孔电极的孔径,模拟燃料电池催化层在不同孔径下的水浓度和水分布规律。同时,考虑温度可能带来的影响,在研究过程中选取了燃料电池常见的运行温度,在每个温度值下都进行了模拟。结果表明,在设定的温度下,孔径对水浓度和水分布情况的影响规律是相似的。孔径较大时,电极内的水浓度较低。随着孔径减小,电极内的水浓度不断增大。同时,孔径越小,水浓度增大的速度越快。气体浓度的分布与变化情况正好与水浓度相反。水浓度越高的区域气体浓度越低。随着孔径减小,气体浓度不断上升。从模拟结果来看,当气体扩散层具有微米级孔隙结构时,电极内多余的水分可以较好地排出,同时在较高的温度下水管理更容易较好地实现。阴极流道出口和中部比较容易发生水淹,所以应该对这些区域加设除水装置或设计自除水结构。

唐口煤矿6315工作面采空区自燃“三带”分布

为了确定唐口煤矿6315工作面采空区遗煤自燃风险范围,对自燃“三带”在不同条件下的分布范围进行分析。以综采采空区为研究对象,利用PFC颗粒流数值模拟软件和FLUENT流场数值模拟软件,建立综采采空区三维空间氧气浓度、流速数学模型,对采空区内部无法直接进行观测的内部流场、气体浓度等进行了模拟计算,得出唐口煤矿6315工作面长度在190 m左右时,工作面采空区自燃“三带”的分布规律。在进风侧,散热带为0~75 m,氧化带为75~88 m,窒息带为88 m以后;在回风侧,散热带为0~35 m,氧化带为35~89 m,窒息带为89 m以后。

一种高温氧指数测定仪

高温氧指数测定仪(high temperature oxygen index tester)是一种用于评估被测材料在高温热辐射条件下燃烧性能的测定仪器。它的工作原理是计算被测材料在高温环境中维持基本的燃烧所需的极限氧浓度来确定被测材料的氧指数。高温氧指数测定仪是对传统氧指数测定设备的升级和补充,可以极大的丰富被测材料的应用领域和使用范围,在阻燃材料、消防工程领域和五金制品材料具有较高的使用意义。