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1
Renz, Andreas, Julian Praß, Johannes Weber e Stefan Becker. "Experimental Investigation of a Friction Ventilator". Advanced Engineering Forum 19 (ottobre 2016): 43–49. http://dx.doi.org/10.4028/www.scientific.net/aef.19.43.
Testo completoAbstract (sommario):
Standard decentralized ventilation systems typically consist of two ventilators for inlet and exhaust air and a heat exchanger for the heat recovery. A recently developed device, a so called friction ventilator, combines these three elements into a single functional element. The ventilator consists of circular plates which are rotating centrally in between the inlet and the outlet duct of a ventilation system and generate a countercurrent flow in the two ducts. Furthermore, the discs act as a rotating heat exchanger between the two air flows. To increase understanding of the energy transfer from the rotating discs to the flow an experimental investigation on the effect of different rotor geometries was conducted. The study showed an interesting influence of the hub diameter on the characteristic curves with a higher pressure difference for an increase in diameter. The results of the heat recovery measurement however were only mildly affected by the hub geometry. Here the distance between the discs, the rotational speed of the discs and the volumetric flow seemed to have the greatest effect on heat recovery.
2
Wu, Juan, Ziming Kou e Jing Liu. "The Acoustical Behavior of Contra-Rotating Fan". Mathematical Problems in Engineering 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/3739067.
Testo completoAbstract (sommario):
The noise produced by a contra-rotating ventilator can cause injury to humans. Therefore, it is important to reduce noise caused by ventilators. In this study, the Ffowcs Williams and Hawkings (FW-H) model was used to simulate the acoustics of four different axial impeller spacing points based on the unsteady flow field through a FBD No. 8.0 contra-rotating ventilator. Experiments were conducted to verify the correctness of the numerical model. Meanwhile, the Variable Frequency Drive (VFD) drives the two motors of 55 kW to give the impellers different speeds to distinguish different conditions. The results showed that the main noise source of the ventilator was the two rotating impellers and the area between them. For the same axial space, the noise decreased with the increase of flow rate and then decreased. And the amplitude of the discrete pulse increased gradually. It can be concluded that the vortex acoustics decreased gradually with the increase of flow rate and the rotating acoustics were the major contributor. With the axial distance increasing, the noise caused by the two impellers was weak, and the frequencies of sound pressure level moved toward medium- and low-frequency bands gradually. The suitable axial space could reduce noise and improve the working environment.
3
Ma, Zhong Fei, Peng Gang Jin e Feng Zhao. "Test on Characteristics of the High-Pressure Secondary Rotary Water Gas Jet Ventilation". Advanced Materials Research 594-597 (novembre 2012): 2167–70. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.2167.
Testo completoAbstract (sommario):
In order to reduce the concentration of explosive gas, experimental research was carried out on the high pressure secondary rotating water jet ventilation characteristic, and the principle of high pressure secondary rotating water jet ventilation was analyzed. Experiments of the relationship between pressure and the suction air flow characteristics were carried out with different structure of jet pipe, different structure of nozzles, different throat in high pressure single rotating water jet ventilation, and the secondary rotating ventilation characteristic were tested with different guide vane angle. The results show that the air-sucking quantity approximatively increased with water pressure in accordance with parabola in the high press secondary rotating water jet ventilator, the air-sucking quantity of different structure of jet pipe was not same, the air-sucking quantity was significantly greater than that of swirl nozzle, the secondary rotary ventilation acts on the larger range.
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Rashid, D. M. H., e N. A. Ahmed. "Study of Aerodynamic Forces on a Rotating Wind Driven Ventilator". Wind Engineering 27, n. 1 (febbraio 2003): 63–72. http://dx.doi.org/10.1260/030952403321833770.
Testo completoAbstract (sommario):
A wind driven ventilator is a simple, cost-effective and environmentally-friendly device that can improve comfort and the working environment. Unfortunately very little is known about the complex flow field associated with the operation of this device. A wind tunnel investigation of the flow associated with a rotating wind ventilator was, therefore, carried out at the aerodynamic laboratory of the University of New South Wales within the Reynolds number range of 1.1 times 105 to 5.5 times 105. An attempt was also made to study some of the important features associated with operation of a rotating wind ventilator using a simple model of a stationary and a spinning cylinder. The results were encouraging and several flow features were identified for future improvement in the performance of a wind ventilator.
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Szabó, Ferenc János, e Ágnes Várkuliné Szarka. "Finite Element Study of Rotating Elements of a Ventilator". International Review of Mechanical Engineering (IREME) 13, n. 6 (30 giugno 2019): 326. http://dx.doi.org/10.15866/ireme.v13i6.17145.
Testo completo
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Farahani. "Simulation of Airflow and Aerodynamic Forces Acting on a Rotating Turbine Ventilator". American Journal of Engineering and Applied Sciences 3, n. 1 (1 gennaio 2010): 159–70. http://dx.doi.org/10.3844/ajeassp.2010.159.170.
Testo completo
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HE, Qiudong. "Analyses on Blade Fracture of Contra-rotating Axial Fan for Mine Local Ventilator and Its Improvement Measures". Journal of Mechanical Engineering 47, n. 24 (2011): 122. http://dx.doi.org/10.3901/jme.2011.24.122.
Testo completo
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Cho, Dong-Hyun. "A Study on the Improvement of Efficiency of Heat Transfer on the Heat Recovery Ventilator with Rotating Porous Disk". Journal of Fisheries and Marine Sciences Education 26, n. 6 (31 dicembre 2014): 1352–57. http://dx.doi.org/10.13000/jfmse.2014.26.6.1352.
Testo completo
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Goto, Takahisa, Hayato Saito, Yoshinori Nakata, Shoichi Uezono, Fumito Ichinose, Masanori Uchiyama e Shigeho Morita. "Effects of Xenon on the Performance of Various Respiratory Flowmeters". Anesthesiology 90, n. 2 (1 febbraio 1999): 555–63. http://dx.doi.org/10.1097/00000542-199902000-00032.
Testo completoAbstract (sommario):
Background The anesthetic gas xenon has distinctly different physical properties compared with air, nitrous oxide, or oxygen. This led us to predict that xenon would affect the performance of commercially available flowmeters. Methods Flow was generated by an anesthesia ventilator connected to a lung simulator via a semiclosed breathing circuit. With the system filled with air or with various concentrations of xenon or nitrous oxide in a balance of oxygen, the tidal volume was measured with two rotating vanes, a Pitot tube, a variable-orifice flowmeter, and two constant-temperature hot-wire flowmeters. Results Although xenon minimally affected both rotating vane flowmeters, it caused the Pitot tube and the variable-orifice flowmeters to overread in proportion to the square root of the density of the gas mixture used (xenon is 4.6 times more dense than air). In contrast, the hot-wire anemometers underread with xenon; for example, their readings in the presence of 45% and 70% xenon were less than 10% of those displayed when air was used. Nitrous oxide minimally affected all the flowmeters except the variable-orifice device. The Pitot flowmeter was also affected, but only when its gas analyzer port was open to the ambient air so that it no longer corrected its readings for changes in gas composition. In these cases, nitrous oxide produced overreadings in the same manner as did xenon. Conclusion Among the four types of flowmeters studied, only the rotating-vane type is sufficiently accurate for use during anesthesia with xenon.
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Shen, Luke Y., Stephen D. Helmer, Jennifer Huang, Gerayu Niyakorn e R. Stephen Smith. "“Shift Work” Improves Survival and Reduces Intensive Care Unit Use in Seriously Injured Patients". American Surgeon 73, n. 2 (febbraio 2007): 185–91. http://dx.doi.org/10.1177/000313480707300220.
Testo completoAbstract (sommario):
We assessed whether a trauma service model with an emphasis on continuity of care by using “shift work” will improve trauma outcomes and cost. This was a case-control cohort study that took place at a university-affiliated Level I trauma center. All patients (n = 4283) evaluated for traumatic injuries between May 1, 2002 and April 30, 2004 were included. During Period I (May 1, 2002 to April 30, 2003), a rotating off-service team provided initial management between 5:00 PM and 7:00 AM. The “day team” provided all other care and was responsible for continuity of care. In Period II (May 1, 2003 to April 30, 2004), a dedicated trauma service consisting of two resident teams evaluated all injured patients. Variables included hospital and intensive care unit length of stay (LOS), mechanical ventilation requirements, hospital mortality, and hospital care costs. Demographics and injury mechanism for both periods were similar, but Injury Severity Score (ISS) in Period II was greater (ISS, 8.2% vs 7.2%, P < 0.0001; ISS > 15, 18.5% vs 15.4%). In the more severely injured (ISS > 15), patients in Period II had shorter hospital LOS (8.6 vs 9.7 days, P = 0.98), a shorter ICU LOS (5.5 vs 7.7 days, P = 0.039), shorter mechanical ventilator requirements (5.5 vs 7.7 days, P = 0.32), improved hospital mortality rate (19.9% vs 26.8%, P = 0.029), and decreased hospital costs ($19,146 vs $21,274, P = 0.36). On multivariate analysis, factors affecting mortality and LOS included age, initial vital signs, injury type, and ISS. Overall, the two trauma service models resulted in similar outcomes. Although multivariate analysis revealed that treatment period did not affect mortality, our study revealed improved patient survival and reduction in LOS and cost for the severely injured in Period II.
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Cortel-LeBlanc, M., J. Landreville, W. Cheung e A. Pan. "P026: Dominating the vent: A flipped classroom approach to enhance emergency medicine resident ventilator management". CJEM 21, S1 (maggio 2019): S72. http://dx.doi.org/10.1017/cem.2019.217.
Testo completoAbstract (sommario):
Innovation Concept: Ventilator management is an essential skill and a training objective for emergency medicine (EM) specialists in Canada. EM trainees obtain the majority of this training during off-service rotations. Previous attempts to strengthen ventilator knowledge include lectures and simulation – both of which are time and resource intensive. Given the unique features of ventilator management in the ED, we developed an ED-specific ventilator curriculum. The purpose of this study is to 1) identify resident needs regarding ventilator curricula and 2) assess resident response to this pilot curriculum. Methods: A needs-assessment survey administered to RCPSC- and CCFP-EM residents at The Ottawa Hospital (TOH) showed the majority of residents (87%, n = 31 respondents) believe there is a need for more ED-focused ventilator management training, and only 13% felt confident in ventilator management. Ten on-line modules were prepared by an EM-Critical Care attending, and distributed on-line to all EM trainees at TOH (n = 52). Mid- and post-implementation surveys are used to assess residents’ confidence in ventilator management, and perceived usefulness of the curriculum. User feedback from focus groups constitutes part of the curriculum evaluation. Curriculum, Tool or Material: Employing a flipped classroom approach, ten on-line modules were distributed to RCPSC- and CCFP-EM trainees at TOH. Each module requires less than ten minutes to complete and focuses on a single aspect of ventilation. The modules are available for residents to complete at their own pace and convenience. At curriculum completion, an EM-Critical Care attending physician facilitates an interactive session. Conclusion: Mid-implementation survey results demonstrate increased confidence in independently managing ventilated patients in the ED (13% pre- vs. 56% mid-implementation), and an increased perception of having sufficient ventilator training (26% pre- vs. 78% mid-implementation). All respondents felt the modules were of appropriate length, content was easy to follow, and that the modules should be part of the residency curriculum. Our ED-specific online ventilator modules area a viable tool to increase residents’ confidence in ventilator management. This novel curriculum could be adopted by other residency programs and continuing professional development initiatives. Future work will include post-implementation data-gathering, and formal curriculum evaluation.
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Lam, Wilfred W., David W. Holdsworth, Louise Y. Du, Maria Drangova, David G. McCormack e Giles E. Santyr. "Micro-CT imaging of rat lung ventilation using continuous image acquisition during xenon gas contrast enhancement". Journal of Applied Physiology 103, n. 5 (novembre 2007): 1848–56. http://dx.doi.org/10.1152/japplphysiol.00009.2007.
Testo completoAbstract (sommario):
We measured ventilation (V̇) in seven anesthetized, mechanically ventilated, supine Wistar rats. Images of the whole lung were continuously acquired using a dynamic, flat-panel volumetric micro-computed tomography (micro-CT) scanner during ventilation with a xenon/oxygen (Xe-O2) gas mixture. Forty time-resolved volumes consisting of eighty 0.45-mm-thick slices (covering the entire lung) were acquired in 40 s, using a gantry rotation rate of one rotation per second. The animals were ventilated at a respiratory rate of 60 breaths/min, matching the gantry rotation rate, and imaged without suspending ventilation. A previously published theoretical model was modified slightly and used to calculate the whole lung ventilation from volumes of interest generated by seeded region growing. Linear regression of calculated whole lung ventilation volumes vs. expected tidal volumes yielded a slope of 1.12 ± 0.11 (slope ± SE) and a y-intercept of −1.56 ± 0.42 ml ( y-intercept ± SE) with 95% confidence intervals of 0.83 to 1.40 and −2.6 to −0.5 ml, respectively. The same model was used to calculate the regional ventilation in axial slices for each animal. Voxels were fit to the model to yield a map of V̇, which displayed an anterior/posterior gravitational gradient of (−3.9 ± 1.8) × 10−6 ml·s−1·cm−1 for slices immediately superior to the diaphragm and (−6.0 ± 2.4) × 10−6 ml·s−1·cm−1 for slices at the midlevel of the heart (mean ± SD). Thus continuous Xe-enhanced computed tomography enables the noninvasive determination of regional V̇ with the temporal and spatial resolution necessary for rats.
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Gol'tsov, A. B., K. I. Logachev, O. A. Averkova, V. A. Tkachenko e I. V. Khodakov. "The investigation of the air flow distribution swirling by the rotating suction cylinder". NOVYE OGNEUPORY (NEW REFRACTORIES), n. 6 (26 luglio 2018): 56–60. http://dx.doi.org/10.17073/1683-4518-2018-6-56-60.
Testo completoAbstract (sommario):
The improvement of the local exhaust ventilation consists in the emission and pollution agents' concentration at the electrical power minimum expenses. The using of the rotating exhaust cylinder in the aspiration hoods can result in the reduction of both the dust loss into the aspiration system and the dust aerosol transportation costs in the air transfer ducts. We investigated the air flow velocity distribution near the rotating exhaust cylinder depending on the rotation frequency and vented air consumption. The obtained results can be applied when the local closed exhaust hoods designing, that is the designing of the aspiration hoods with the dust-collecting chambers.
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Kang, So Yeon, Michael DiStefano, Farah Yehia, Maria Koszalka e William Padula. "PD76 The Value Of Continuous Lateral Rotation Therapy In The ICU". International Journal of Technology Assessment in Health Care 34, S1 (2018): 156. http://dx.doi.org/10.1017/s0266462318003306.
Testo completoAbstract (sommario):
Introduction:Mechanical ventilation in the intensive care unit (ICU) increases the risk of hospital-acquired conditions (HACs) such as ventilator-associated pneumonia (VAP) and pressure injuries (PrI). Continuous lateral rotation therapy (CLRT) has been shown to reduce VAP and PrI incidence, but the value of switching to CLRT over standard care is presently unknown. We evaluate the cost-effectiveness of CLRT beds compared to standard care in ICUs and determine the return on investment (ROI) associated with its implementation.Methods:A Markov model was constructed to predict health state transitions from the time of ventilation through 28 days using the healthcare sector perspective. Daily transition probabilities were extrapolated from prospective clinical studies comparing CLRT with standard care. Costs were estimated in 2014 USD. Utility scores were extracted from the published literature. Cost per quality-adjusted life-years (QALYs) was calculated and sensitivity analyses were conducted. A secondary analysis from a societal perspective with a one-year time horizon included the costs of patient and caregiver lost productivity. ROI analysis was performed to estimate the net benefit and breakeven point of the investment. Value of Information analysis was performed to determine whether further research is warranted.Results:From both perspectives, CLRT was dominant. From the healthcare sector perspective, the expected cost for CLRT per patient was USD 47,165 compared to standard care at USD 49,258 per patient, showing that CLRT saves cost per patient. The expected effectiveness of CLRT per patient was 0.0418 QALYs compared to 0.0416 QALYs for standard care. CLRT was dominant in 99.94 percent of Monte Carlo simulations. CLRT also reached the break-even point after 5 months. Expected Value of Perfect Information was equal to 0.019, indicating little value of additional evidence at the current level of parameter uncertainty.Conclusions:CLRT is highly cost-effective compared to standard care by preventing ventilator-associated infections and PrIs in an ICU setting.
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Whiteman, K., L. Nachtmann, D. Kramer, S. Sereika e M. Bierman. "Effects of continuous lateral rotation therapy on pulmonary complications in liver transplant patients". American Journal of Critical Care 4, n. 2 (1 marzo 1995): 133–39. http://dx.doi.org/10.4037/ajcc1995.4.2.133.
Testo completoAbstract (sommario):
BACKGROUND: When liver transplant candidates and recipients suffer from pulmonary complications of immobility, the results can be life-threatening. Continuous lateral rotation therapy has been reported to decrease complications of immobility. OBJECTIVES: To determine whether continuous lateral rotation therapy decreases the duration of mechanical ventilation, intensive care unit length of stay, incidence or resolution of atelectasis, incidence or onset time of lower respiratory tract infection and pneumonia. METHODS: Sixty-nine subjects admitted to a liver transplant intensive care unit at a university teaching hospital were randomly assigned to continuous lateral rotation therapy or a stationary bed. All subjects were mechanically ventilated for 24 hours and had a Glasgow Coma Scale score of 11 or less upon admission to the study. Subjects were followed until out of bed, unable to rotate for 3 consecutive days, or transferred from the intensive care unit. Data and chest roentgenogram results were collected on admission and daily during the study. Sputum culture results were obtained if available as part of normal patient care. RESULTS: Incidence of lower respiratory tract infection was significantly lower and length of time to occurrence of lower respiratory tract infection was significantly longer in the continuous lateral rotation therapy group than in the stationary bed group. CONCLUSIONS: Although continuous lateral rotation therapy did not affect duration of mechanical ventilation, length of stay, or incidence of atelectasis, it was effective in decreasing the incidence of, and increasing onset time to, lower respiratory tract infection in the liver transplantation population.
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Whitelaw, W. A., G. T. Ford, K. P. Rimmer e A. De Troyer. "Intercostal muscles are used during rotation of the thorax in humans". Journal of Applied Physiology 72, n. 5 (1 maggio 1992): 1940–44. http://dx.doi.org/10.1152/jappl.1992.72.5.1940.
Testo completoAbstract (sommario):
To test the idea that the lateral intercostal muscles may be more suited to aid in rotational than respiratory movements of the thorax, we inserted bipolar fine-wire electrodes in external and internal intercostal muscles in the right midaxillary line in nine sitting subjects and examined the pattern of contraction of these muscles during voluntary axial rotations of the thorax (30–35 degrees), resting breathing, and CO2-induced hyperpnea. The right external intercostal muscles were strongly recruited in rotations to the left but were not active in rotations to the right. In contrast, the right internal intercostal muscles were active in rotations to the right but not in rotations to the left. Rotations completed in 1 or 2 s were associated with an early burst of electromyographic activity, followed by a low plateau that persisted while the rotation was held. Rotations made very gradually over 5–10 s were associated with gradually rising electromyographic activity. The amplitude of activity recorded during 30–35 degrees rotations was equivalent to that measured when minute ventilation was increased by CO2 to 50 l/min. We conclude that the lateral intercostal muscles have a major role in producing axial rotations of the thorax.
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Schmidt, Ulrich H., Kanya Kumwilaisak, Edward Bittner, Edward George e Dean Hess. "Effects of Supervision by Attending Anesthesiologists on Complications of Emergency Tracheal Intubation". Anesthesiology 109, n. 6 (1 dicembre 2008): 973–77. http://dx.doi.org/10.1097/aln.0b013e31818ddb90.
Testo completoAbstract (sommario):
Background Emergent intubation is associated with a high complication rate. These intubations are often performed by resident physicians in teaching hospitals. The authors evaluated whether supervision by an anesthesia-trained intensivist decreases complications of emergent intubations. Methods The authors performed a prospective cohort study in an Academic Tertiary Care Hospital. They enrolled 322 consecutive patients who required emergent intubation between November 1, 2006, and April 15, 2008. Emergency intubations are performed by anesthesia residents during their surgical intensive care unit rotation. An attending anesthesiologist was assigned to supervise these intubations at predetermined periods. A respiratory therapist assisted with airway management and ventilation. Information related to the intubation, detailing patient demographics, indication for intubation, attending anesthesiologist presence, medications used, and immediate complications, was recorded. Disposition and duration of mechanical ventilation were also recorded. Results There were no differences in demographics, clinical characteristics, or illness severity among patients intubated with and without attending supervision. Attending physician supervision was associated with a significant decrease in complications (6.1% vs. 21.7%; P = 0.0001). There was no difference in ventilator-free days or 30-day mortality. Conclusion Supervision by an attending anesthesiologist was associated with a decreased incidence of complications during emergent intubations.
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Y., Gerasymchuk,, Adamenko, O., Lavrishchev, A. e Novoselytskiy, Y. "Determination parameters of the precipitating electrode of the electrotechnical means for cleaning air of livestock buildings from harmful gases and bacterial contamination". Mehanization and electrification of agricultural, n. 9(108) (2019): 141–48. http://dx.doi.org/10.37204/0131-2189-2019-9-17.
Testo completoAbstract (sommario):
Purpose. Get dependence to determine the mass of the chemical adsorbent which is contained on the rotating precipitating electrode of the electrotechnical means, taking into account the kinetics of the process of air purification of livestock buildings from harmful gases and bacterial contamination with the complex use of electrophysical and chemical methods of decontamination and air purification. Methods. Analysis of the influence of chemical adsorbent and crown discharge field on the efficiency of air purification of livestock buildings from harmful gases and bacterial contamination. Experimental researches for determination of basic parameters of a precipitating electrode of an electrotechnical means. Results. Scheme of the electrotechnical means with the complex using of electrophysical and chemical methods of purification and disinfection of recirculation air of ventilation emissions from ammonia, carbon dioxide, hydrogen sulfide and bacterial contamination. Polynomial dependence for determining the mass of a chemical adsorbent which is contained on a rotating depositing electrode. Conclusions. Complex using of the electrotechnical means for air purification from harmful gases and bacterial contamination of the recirculation air flow and the utilization heat of ventilation emissions with the implementation anti-icing protection heat exchange surface of the recuperative heat utilizers allows to reduce the level of air exchange and significantly reduce energy costs to provide regulatory airspace of livestock buildings in the cold season. On the disks of precipitating electrodes of an electrotechnical mean for cleaning and disinfection of recirculation air of ventilation emissions, it is necessary to fix a polymer mesh with an area of cellules of 16 mm2, and the frequency rotation of the discs to support within the range from 0.25 s-1 to 1 s-1. Keywords: microclimate, heat utilizer, recuperate, air purification, corona discharge, precipitating electrode.
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Que, Cheng-Li, Christof Kolmaga, Louis-Gilles Durand, Suzanne M. Kelly e Peter T. Macklem. "Phonospirometry for noninvasive measurement of ventilation: methodology and preliminary results". Journal of Applied Physiology 93, n. 4 (1 ottobre 2002): 1515–26. http://dx.doi.org/10.1152/japplphysiol.00028.2002.
Testo completoAbstract (sommario):
We measured tracheal flow from tracheal sounds to estimate tidal volume, minute ventilation (V˙i), respiratory frequency, mean inspiratory flow (Vt/Ti), and duty cycle (Ti/Ttot). In 11 normal subjects, 3 patients with unstable airway obstruction, and 3 stable asthmatic patients, we measured tracheal sounds and flow twice: first to derive flow-sound relationships and second to obtain flow-volume relationships from the sound signal. The flow-volume relationship was compared with pneumotach-derived volume. When subjects were seated, facing forward and with neck rotation, flexion, and standing, flow-volume relationship was within 15% of pneumotach-derived volume. Error increased with neck extension and while supine. We then measured ventilation without mouthpiece or nose clip from tracheal sounds during quiet breathing for up to 30 min. Normal results ± SD revealed tidal volume = 0.37 ± 0.065 liter, respiratory frequency = 19.3 ± 3.5 breaths/min, V˙i = 6.9 ± 1.2 l/min, Vt/Ti = 0.31 ± 0.06 l/s, and Ti/Ttot = 0.37 ± 0.04. Unstable airway obstruction had large V˙i due to increased Vt/Ti. With the exception of Ti/Ttot, variations in ventilatory parameters were closer to log normal than normal distributions and tended to be greater in patients. We conclude that phonospirometry measures ventilation reasonably accurately without mouthpiece, nose clip, or rigid postural constraints.
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Gor, D., J. A. C. Humphrey e R. Greif. "Ventilated Flow Between Corotating Disks With Large Obstructions in a Fixed Cylindrical Enclosure (Data Bank Contribution)". Journal of Fluids Engineering 116, n. 4 (1 dicembre 1994): 828–34. http://dx.doi.org/10.1115/1.2911857.
Testo completoAbstract (sommario):
Time-resolved laser-Doppler velocimeter measurements of the circumferential velocity component were obtained for the flow between the center pair of four disks of common radius R2 corotating at angular velocity Ω in a fixed, cylindrical enclosure. Mean and rms profiles of this velocity component were obtained for two disk rotation speeds (300 and 3600 rpm), two relatively thick tapered obstructions (long and short) placed radially inward midway between each pair of disks, and three ventilation conditions (unventilated, blowing, and sucking) resulting from an imposed inter-disk radial throughflow. The profiles were determined at four circumferential locations downstream of the respective obstructions; radially along the midplane, and axially at selected radial locations. The profiles for the unventilated flow case show that the circumferential component of motion signficantly accelerates near the hub, in the region between the tip of the obstruction and the rotating hub. Elsewhere, this component of motion is significantly decelerated. The presence of ventilation, whether directed radially outward or inward, significantly affects the flow field only in the region immediately around the hub, and far downstream of the obstruction where it increases both the mean and rms velocities. Analysis of the time records suggests that the observed increases in the rms values are due to the circumferentially periodic nature of the radial ventilation condition. These observations are, for the most part, independent of the disk speed of rotation and the length of the obstructions. A comparison of present unventilated flow results with the corresponding results of Usry et al. (1993), who used much thinner obstructions, reveals the extent to which increasing the obstruction blockage ratio induces larger levels of flow unsteadiness.
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Rodríguez-Nieto, M. J., G. Peces-Barba, N. González Mangado, S. Verbanck e M. Paiva. "Single-breath washouts in a rotating stretcher". Journal of Applied Physiology 90, n. 4 (1 aprile 2001): 1415–23. http://dx.doi.org/10.1152/jappl.2001.90.4.1415.
Testo completoAbstract (sommario):
Vital capacity single-breath washouts using 90% O2-5% He-5% SF6 as a test gas mixture were performed with subjects sitting on a stool (upright) or recumbent on a stretcher (prone, supine, lateral left, lateral right, with or without rotation at end of inhalation). On the basis of the combinations of supine and prone maneuvers, gravity-dependent contributions to N2 phase III slope and N2 phase IV height in the supine posture were estimated at 18% and 68%, respectively. Whereas both He and SF6 slope decreased from supine to prone, the SF6-He slope difference actually increased ( P = 0.015). N2 phase III slopes, phase IV heights, and cardiogenic oscillations were smallest in the prone posture, and we observed similarities between the modifications of He and SF6 slopes from upright to prone and from upright to short-term microgravity. These results suggest that phase III slope is partially due to emptying patterns of small units with different ventilation-to-volume ratios, corresponding to acini or groups of acini. Of all body postures under study, the prone position most reduces the inhomogeneities of ventilation during a vital capacity maneuver at both inter- and intraregional levels.
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Tasic, Milan, Radivoje Mitrovic, Predrag Popovic e Marko Tasic. "Influence of running conditions on resonant oscillations in fresh-air ventilator blades used in thermal power plants". Thermal Science 13, n. 1 (2009): 139–46. http://dx.doi.org/10.2298/tsci0901139t.
Testo completoAbstract (sommario):
High frequency cyclic load of fresh air supply to ventilator blades in thermo energetic facilities can cause the occurrence of fretting in the pressed overlap of ventilator shaft and socket. These loads can be generated by the resonant oscillations of ventilator blades and thermal residual stress due to welding. To prevent running in resonant conditions, the manufacturer of the ventilator defined a procedure of adjusting blades natural frequency in the process of production, as well as period control during exploitation period. The numerical simulations and the accelerations measured and presented in this paper, enabling analysis of mass changes and rotation rate effects on resonant oscillations occurrence in fresh air ventilator.
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Staudinger, Thomas, Andja Bojic, Ulrike Holzinger, Brigitte Meyer, Marion Rohwer, Friederike Mallner, Peter Schellongowski et al. "Continuous lateral rotation therapy to prevent ventilator-associated pneumonia*". Critical Care Medicine 38, n. 2 (febbraio 2010): 486–90. http://dx.doi.org/10.1097/ccm.0b013e3181bc8218.
Testo completo
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Lu, Yi Ping, Qing Hui Pan, Hui Lan Li e Jia De Han. "Experimental Study of Flow Field of Large Air-Cooled Turbine Generator for Multi-Ventilation Ducts of Stator". Applied Mechanics and Materials 644-650 (settembre 2014): 377–80. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.377.
Testo completoAbstract (sommario):
To study rotational air flow field of rotor and complicated flow distinction owing to multi-ventilation ducts of stator in a large air-cooled turbine generator, considering axial symmetry of air supply, an experiment setup of ventilation system of semi-machine configuration was built in this paper. At condition of rotating, ventilation is measured by hot-wire anemometer. Firstly, ventilation in 16 different semi-circle radius is got. Measurement shows that ventilation in different radius varies much. Then ventilation of outlet of stator ducts is measured. The result shows that ventilation which is affected by flow back and jet less is higher. The conclusion will provide theoretical references for ventilation cooling of rotor ducts in large air-cooled turbine generators.
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Ahrens, Thomas, Marin Kollef, Jena Stewart e William Shannon. "Effect Of Kinetic Therapy on Pulmonary Complications". American Journal of Critical Care 13, n. 5 (1 settembre 2004): 376–82. http://dx.doi.org/10.4037/ajcc2004.13.5.376.
Testo completoAbstract (sommario):
• Background Optimal turning of critically ill patients is not well established. Kinetic therapy (systematic mechanical rotation of patients with 40° turns) may improve pulmonary function more than the improvement in function achieved via the standard of care (turning patients every 2 hours).• Objective To determine (1) if patients receiving mechanical ventilation who tolerate kinetic therapy have better pulmonary function than do patients treated with standard turning and (2) the cost-effectiveness of kinetic therapy.• Methods A prospective, randomized, multicenter study including 234 medical, surgical, and trauma patients (137 control patients, 97 patients receiving kinetic therapy).• Results Kinetic therapy significantly decreased the occurrence of ventilator-associated pneumonia and lobar atelectasis. The risk of pneumonia developing was lower (P = .002) in patients receiving kinetic therapy than in the control patients. The risk of lobar atelectasis developing was decreased (P = .02) for the patients receiving kinetic therapy. Lengths of stay in the intensive care unit and in the hospital did not differ between the groups. Charges for intensive care were less in the kinetic therapy group ($81 700) than in the control group ($84 958), but not significantly less. Twenty-one patients did not tolerate kinetic therapy and were not included in the analysis.• Conclusion Kinetic therapy helps prevent ventilator-associated pneumonia and lobar atelectasis in critically ill patients. Costs to rent the bed may be offset by the potential cost reduction associated with kinetic therapy.
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Suryadi, Aris. "THE IMPLEMENTATION OF TURBINE VENTILATOR AS AN ALTERNATIVE POWER PLANT". ADI Journal on Recent Innovation (AJRI) 2, n. 1 (21 gennaio 2020): 180–85. http://dx.doi.org/10.34306/ajri.v2i1.34.
Testo completoAbstract (sommario):
Indonesia is actively developing the potential for renewable energy as a substitute for depleting fossil energy reserves. Wind energy is clean energy without polling the environment. Wind energy in Indonesia has great potential, but it is still not optimal enough for its utilization. One form of alternative energy that can be utilized as mechanical energy by wind turbines to convert into electrical energy by dc generators. Ventilators that operate for 24 hours function to suck water and, located on the roof of a warehouse, sports hall . Utilization of wind to become electrical energy is designed from the use of a turbine ventilator as a medium to convert wind into motion energy, where the movement of the turbine is continued by pulley and v-belt comparisons to the generator, this generator produces electricity. This research examines how much electrical energy is produced at different wind speeds ranging from 3 to 5.4 m/s. From the tests conducted, the generator rotation, and the lowest voltage is at wind speed of 3 m/s which is 3.6 V. while the generator speed and the highest voltage is obtained if the wind speed is 5.4 m/s which is 10.3 V.
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Koopman, Maud, Martijn A. Spruit, Frits M. E. Franssen, Jeannet Delbressine, Emiel F. M. Wouters, Denny Mathew, Anton Vink e Lowie E. G. W. Vanfleteren. "Effects of Non-Invasive Ventilation Combined with Oxygen Supplementation on Exercise Performance in COPD Patients with Static Lung Hyperinflation and Exercise-Induced Oxygen Desaturation: A Single Blind, Randomized Cross-Over Trial". Journal of Clinical Medicine 8, n. 11 (18 novembre 2019): 2012. http://dx.doi.org/10.3390/jcm8112012.
Testo completoAbstract (sommario):
The effects of non-invasive ventilation (NIV) in addition to supplemental oxygen on exercise performance in patients with chronic obstructive pulmonary disease (COPD) with hyperinflation and exercise-induced desaturation (EID) remain unclear. We hypothesized that these patients would benefit from NIV and that this effect would be an add-on to oxygen therapy. Thirteen COPD patients with a residual volume >150% of predicted, normal resting arterial oxygen pressure (PaO2) and carbon-dioxide pressure (PaCO2) and EID during a six-minute walk test were included. Patients performed four constant work-rate treadmill tests, each consisting of two exercise bouts with a recovery period in between, wearing an oronasal mask connected to a ventilator and oxygen supply. The ventilator was set to the following settings in fixed order with clockwise rotation: Sham (continuous positive airway pressure (CPAP) 2 cm H2O, FiO2 21%), oxygen (CPAP 2 cm H2O, FiO2 35%), NIV and oxygen (inspiratory positive airway pressure (IPAP) 14 cm H2O/expiratory positive airway pressure (EPAP) 6 cm H2O, inspired oxygen fraction (FiO2) 35%), intermittent (walking: Sham setting, recovery: NIV and oxygen setting). During the first exercise, bout patients walked further with the oxygen setting compared to the sham setting (225 ± 107 vs 120 ± 50 meters, p < 0.05), but even further with the oxygen/NIV setting (283 ± 128 meters; p < 0.05). Recovery time between two exercise bouts was shortest with NIV and oxygen. COPD patients with severe static hyperinflation and EID benefit significantly from NIV in addition to oxygen during exercise and recovery.
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Jordan, Rebecca M., Lauryn A. Ullrich, Alexandria Decapua-Guarino e Brian Klock. "Trends in Surgical Critical Care Training Among General Surgery Residents: Pursuing an Ideal Curriculum". American Surgeon 86, n. 9 (17 agosto 2020): 1119–23. http://dx.doi.org/10.1177/0003134820943551.
Testo completoAbstract (sommario):
Background The Accreditation Council for Graduate Medical Education (ACGME) provides no specific guidelines for surgical critical care (SCC) training during general surgery residency. Growing emphasis is placed on this experience with increasing case requirements and dedicated SCC content on board certification exams. Methods A digital survey was distributed to ACGME-accredited general surgery residencies via email. Respondents reported number and setting of critical care months during residency and rated comfort level within 5 critical care principles and overall satisfaction with their SCC experience. Study cohorts were formed to compare experiences and competencies between respondents based on setting, months, postgraduate year (PGY) level, and formal surgical intensive care unit (SICU) experience. Differences between cohorts were compared using the Mantel-Haenszel test ( P < .05). Results Seventy-three residents responded with 45% training at academic centers versus 46% in community hospitals. Approximately 50% completed a formal SICU rotation, while 9% reported no dedicated critical care rotation during residency. Overall, 78% felt satisfied with their SCC experience. Residents training at academic centers were more satisfied overall and felt more comfortable with ventilator management. Those who completed 5 or more months of critical care training reported greater confidence with intravenous sedation and ventilator management, while residents having a formal SICU rotation felt more confident with vasopressor and ventilator management. Discussion Variability remains within SCC training among general surgery residents with perceived benefits seen in training at academic centers and completing a formal SICU rotation. Although limited, these findings offer a foundation for developing an effective SCC curriculum.
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Zhang, Qun Feng, Jin Li Yan, Min Wang e Zhi Xiang Chen. "CFD Application on Ventilation System of Hydro-Generator". Advanced Materials Research 383-390 (novembre 2011): 3561–65. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3561.
Testo completoAbstract (sommario):
Averaged 3D N-S equations and RNG k-ε equations were solved with parallel computing CFD code on the flow field of dual radial ventilation system without fan for a hydro-generator. The MRF(multiple implicit rotating frame) method was used to simulated the rotating motion of the generator and porous media model were used to simulate the pressure loss of air cooler. Rational tactics were selected to generate calculation grids to compromise with calculation CPU time and result accuracy and the grids of different parts were generated with ICEM-CFD. The flow characteristic of different parts was analyzed and flow flux of different section was obtained. The research indicated that the flow from leakage gap between poles and stators formed "air wall", which generated a recirculation zone and made the bar cooling bad. The local pressure loss of stator entrance is dominant. There are leeward and windward areas for the air flowing with circumferential velocity component. Rational design of stator ducts entrance with some diversion effect, can reduce the pressure loss of the stator ventilation and improve the cooling of leeward area in stator ducts.
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Gretchikhin, L. I., e A. I. Hutkouski. "Air Heat Pump in Wind Power". ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 63, n. 3 (28 maggio 2020): 264–84. http://dx.doi.org/10.21122/1029-7448-2020-63-3-264-284.
Testo completoAbstract (sommario):
An experimental facility has been developed and manufactured to study the disruptive flow in an air heat pump. The propeller of the heat pump does not produce pulling or pushing forces. The external air flow is created by a high speed propeller perpendicular to the plane of rotation of the heat pump propeller and acts as a ventilator. Herewith, a disruptive flow in the back side of the heat pump propeller is being created and conditions for converting the thermal component of the ventilator air flow into electrical energy by an electric power generator are realized. An aerodynamic model of the flow around the propeller blades of the heat pump in mutually perpendicular airflow has been developed. Experimental studies of the operating propeller as a heat pump, taking into account the friction during rotation of the rotor in the stator of the electric generator, were carried out. In order for the air heat pump to perceive the impacting air flow from the ventilator, it must rotate with minimal power. As a result, for two standard twin-bladed propellers mounted on a 100 W engine under the wind generated by the ventilator which speed is 2.17 m/s the conversion factor was 5.04. As the speed of air flow from the ventilator increased, the conversion coefficient decreased sharply. When placing the two specified propellers on a 300 W motor, the minimum pre-rotation power was 5.7 W. In this case, when an air flow speed is of 1.08 m/s, the conversion coefficient reached only 2.93 and also fell sharply with the increase in the air flow speed. When a three-blade propeller with blades was used on a 300 W motor, then situation has changed dramatically. When the motor with a special propeller with a power of 12.1 W was spun and the air flow was formed at a speed of 3.2 m/s, the conversion coefficient was 12.4. With the reduction in the power of the spinup down to 5.9 W and in the speed of the air flow created by the ventilator to 1.7 m/s, the conversion coefficient increased to 14.9. The theoretical calculation of heat pump conversion coefficient is confirmed by experimental data. The conditions under which this coefficient reaches its maximum value are set. Computer modeling of different designs of heat pump propeller blades was performed. It is demonstrated that an air heat pump is a complex open energy system.
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Onuki, Takashi, Shinji Wakao, Hiroaki Takahashi, Masato Tokuhisa e Jee Won Im. "Design Optimization of Ventilation Holes in Rotating Machines with High Power Density". IEEJ Transactions on Power and Energy 118, n. 10 (1998): 1110–15. http://dx.doi.org/10.1541/ieejpes1990.118.10_1110.
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Denson, Joshua Lee, Julie Knoeckel, Sara Kjerengtroen, Rachel Johnson, Bryan McNair, Olivia Thornton, Ivor S. Douglas, Michael E. Wechsler e Robert E. Burke. "Improving end-of-rotation transitions of care among ICU patients". BMJ Quality & Safety 29, n. 3 (4 novembre 2019): 250–59. http://dx.doi.org/10.1136/bmjqs-2019-009867.
Testo completoAbstract (sommario):
BackgroundHospitalised patients whose inpatient teams rotate off service experience increased mortality related to end-of-rotation care transitions, yet standardised handoff practices are lacking.ObjectiveDevelop and implement a multidisciplinary patient-centred handoff intervention to improve outcomes for patients who are critically ill during end-of-rotation transitions.Design, setting and participantsSingle-centre, controlled pilot study of medical intensive care unit (ICU) patients whose resident team was undergoing end-of-rotation transition at a university hospital from June 2017 to February 2018.InterventionA 4-item intervention was implemented over two study periods. Intervention 1 included: (1) in-person bedside handoff between teams rotating off and on service, (2) handoff checklist, (3) nursing involvement in handoff, and (4) 30 min education session. Intervention 2 included the additional option to conduct bedside handoff via videoconferencing.Main outcome measuresImplementation was measured by repeated clinician surveys and direct observation. Patient outcomes included length of stay (LOS; ICU and hospital) and mortality (ICU, hospital and 30 days). Clinician perceptions were modelled over time using per cent positive responses in logistic regression. Patient outcomes were compared with matched control ‘transition’ patients from 1 year prior to implementation of the intervention.ResultsAmong 270 transition patients, 46.3% were female with a mean age of 55.9 years. Mechanical ventilation (64.1%) and in-hospital death (27.6%) rates were prevalent. Despite high implementation rates—handoff participation (93.8%), checklist utilisation (75.0%), videoconferencing (62.5%), nursing involvement (75.0%)—the intervention did not significantly improve LOS or mortality. Multidisciplinary survey data revealed significant improvement in acceptability by nursing staff, while satisfaction significantly declined for resident physicians.ConclusionsIn this controlled pilot study, a structured ICU end-of-rotation care transition strategy was feasible to implement with high fidelity. While mortality and LOS were not affected in a pilot study with limited power, the pragmatic strategy of this intervention holds promise for future trials.
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Girard, John, e Scott Abrahamson. "On the Flow Structure Due to Corotating Disks With a Ventilated Hub". Journal of Fluids Engineering 115, n. 3 (1 settembre 1993): 408–10. http://dx.doi.org/10.1115/1.2910153.
Testo completoAbstract (sommario):
The effects of hub ventilation on the flow structure between corotating disks enclosed in a stationary cylindrical shroud have been studied using quantitative flow visualization. The ventilation flow resulted from the pumping of the rotating disks. The geometry of the ventilation holes and the total open area were varied and the flow structure was compared to the solid hub case. Many of the features present in the solid hub case remained in modified form. The radial extent of the region purged by the through-flow was independent of the hub open area, which ranged from 3.4 to 37.5 percent of the total hub area. Additionally, the radial extent of the purged region was found to be independent of the Reynolds number.
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Berra, Lorenzo, Massimo Cressoni, Gianluigi Li Bassi, Theodor Kolobow, Mauro Panigada e Alberto Zanella. "Continuous lateral rotation therapy to prevent ventilator-associated pneumonia: The neglected effects of gravity on pathogenesis of ventilator-associated pneumonia". Critical Care Medicine 38, n. 3 (marzo 2010): 1018–19. http://dx.doi.org/10.1097/ccm.0b013e3181cc40fc.
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Staudinger, Thomas. "Continuous lateral rotation therapy to prevent ventilator-associated pneumonia: The neglected effects of gravity on pathogenesis of ventilator-associated pneumonia". Critical Care Medicine 38, n. 3 (marzo 2010): 1019. http://dx.doi.org/10.1097/ccm.0b013e3181cfb57b.
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Wu, Wei Xiong, Yun Zhao e Jie Qiang Zhao. "A Controller Development Based on PLC for Climate Control of Agricultural Greenhouses". Applied Mechanics and Materials 336-338 (luglio 2013): 1266–70. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.1266.
Testo completoAbstract (sommario):
Forced ventilation has more accuracy in climate control of agricultural greenhouses. It is worthwhile to apply some energy saving measures to overcome the disadvantage of high power consumption in fan driving of forced ventilation. Here we present a new developed controller based on PLC which mainly can control the ventilation fans rotation speed in combination with variable frequency drive except for manipulating other facilities in greenhouse like pad, shading screen etc. The control system integrates a sense module which measuring solar radiation, temperature and humidity inside and outside of greenhouse, an actuating module which includes variable frequency drive, pad control and radiation screens to perform a optimized cooling strategy to reduce electrical energy consumption by low down the fans rotation speed with ambient condition changes.
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Mishra, Sandeep Kumar, Mohammad Nawaz, M. V. S. Satyapraksh, Satyen Parida, Prasanna Udupi Bidkar, Balachander Hemavathy e Pankaj Kundra. "Influence of Head and Neck Position on Oropharyngeal Leak Pressure and Cuff Position with the ProSeal Laryngeal Mask Airway and the I-Gel: A Randomized Clinical Trial". Anesthesiology Research and Practice 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/705869.
Testo completoAbstract (sommario):
Background. This study was designed to assess and compare the effect of head and neck position on the oropharyngeal leak pressures and cuff position (employing fibreoptic view of the glottis) and ventilation scores between ProSeal LMA and the I-gel.Material and Methods. After induction of anesthesia, the supraglottic device was inserted and ventilation confirmed. The position of the head was randomly changed from neutral to flexion, extension, and lateral rotation (left). The oropharyngeal leak pressures, fibreoptic view of glottis, ventilation scores, and delivered tidal volumes and end tidal CO2were noted in all positions.Results. In both groups compared with neutral position, oropharyngeal leak pressures were significantly higher with flexion and lower with extension but similar with rotation of head and neck. However the oropharyngeal leak pressure was significantly higher for ProSeal LMA compared with the I-gel in all positions. Peak airway pressures were significantly higher with flexion in both groups (however this did not affect ventilation), lower with extension in ProSeal group, and comparable in I-gel group but did not change significantly with rotation of head and neck in both groups.Conclusion. Effective ventilation can be done with both ProSeal LMA and I-gel with head in all the above positions. ProSeal LMA has a better margin of safety than I-gel due to better sealing pressures except in flexion where the increase in airway pressure is more with the former. Extreme precaution should be taken in flexion position in ProSeal LMA.
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Hamlin, Shannan K., Sandra K. Hanneman, Sheryln Wachtel e Gary Gusick. "Adverse Hemodynamic Effects of Lateral Rotation During Mechanical Ventilation". Dimensions of Critical Care Nursing 27, n. 2 (marzo 2008): 54–61. http://dx.doi.org/10.1097/01.dcc.0000311593.87097.6a.
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Zheng, Jianwen, Qiuhua Tao e Li Li. "Wind Pressure Coefficient on a Multi-Storey Building with External Shading Louvers". Applied Sciences 10, n. 3 (7 febbraio 2020): 1128. http://dx.doi.org/10.3390/app10031128.
Testo completoAbstract (sommario):
Wind characteristics on building surfaces are used to evaluate natural ventilation of a building. As a type of building component, external shading louvers are applied in hot climatic regions to block solar radiation and provide better visual environments. The structure of external louvers can affect wind-induced characteristics, such as convective heat transfer coefficient, wind pressure and pollutant dispersion around building envelopes. This paper aims to analyze the potential ventilation capacity of a multi-storey building with shading louvers, based on wind pressure coefficient by the numerical method. A reference case was established and a previous study was applied to validate the numerical results. The rotation angle of horizontal louvers is taken from 0° to 75° in the simulation cases. The results show that average wind pressure has the greatest reduction for all floors when rotation angle turns from 60° to 75°. Ventilation openings on the stagnation zone contribute to higher ventilation rates for the windward facade with louvers. The analysis, based on multi-floor and multi-row buildings under shaded conditions, will provide a greater perspective for engineers to make optimal natural ventilation routes in multi-storey buildings with external shading louvers.
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Wang, Yi, Pan Lu, Hai Bing Yao, Jia Ping Liu e Lu Lu Chen. "The Analysis of the Impact of the Louver on the Natural Ventilation". Advanced Materials Research 243-249 (maggio 2011): 6997–7000. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.6997.
Testo completoAbstract (sommario):
The louver affects natural ventilation rate and indoor air distribution. In this paper, the wind velocity profile and pressure distribution in the natural ventilation model building were simulated through CFD. And how different rotation angles of the shutter and different incidence angles of the wind affect natural ventilation rate were studied. Then, the influences of shutters on the discharge coefficients were analyzed, and use principles of the louver equipped in the building were proposed.
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Myhal, I. I., U. A. Fesenko, A. O. Dvorakevich e A. A. Albokrinov. "The ventilation parameters during the Nuss procedure for repair of pectus excavatum". Acta Medica Leopoliensia 26, n. 2-3 (2020): 28–37. http://dx.doi.org/10.25040/aml2020.02-03.028.
Testo completoAbstract (sommario):
The ventilation parameters during the Nuss procedure for repair of pectus excavatum depend on surgical procedures and airway protection technique. The aim of the study: analyzing the ventilation parameters during the Nuss procedure for repair of pectus excavatum according to the airway protection technique. Material and Methods. The observational prospective study included 60 adolescents (boys/girls=47/13) who had undergone the Nuss procedure for repair of pectus excavatum under a combination of general anesthesia with different types of regional blocks. The patients were randomized into two groups (n=20 in each) according to the airway protection technique: Group S (n=32) where the patients were intubated with a standard single-lumen tube, and capnothorax with 4-6 mmHg intrapleural pressure was applied; Group D (n=28) where the patients were intubated with a double-lumen tube, and open pneumothorax was applied without additional pressure in the thoracic cavity. All patients were ventilated using PCV with changing of the parameters in relevance with EtCO2. The following parameters were analyzed: peripheral blood saturation (SpO2), inspiratory fractional oxygen concentration (FiO2), end-tidal carbon dioxide partial pressure (EtCO2), tidal volume (Tv), peak inspiratory pressure (PIP), positive end-expiratory pressure (PEEP), the number of repeated intubation attempts, and the quality of operation field visualization checked by surgeon with a 5-point scale. Results and Discussion. During capno/pneumothorax and bar rotation, in both groups SpO2 decreased up to 95%, which required increasing FiO2 up to 70% in Group D, and up to 63% in Group S (р=0.04). Applying capno/pneumothorax lead to reduced Tv, which was 52 ml less in Group D than in Group S (р=0.0001). The levels of EtCO2, PIP, and PEEP were comparable in both groups at all stages of the surgery. The number of repeated intubation attempts was- 1 case (3,1%) in group S, and 2 cases (7,1%) in group D: c2 = 0,51; p=0.48, the adjusted c22 = 3.84 for p <0.05. The quality of operation field visualization evaluated by the surgeons with the 5-point scale was better in Group D (4.5 points), than in Group S - 3 points (р<0.000001) at all stages. Conclusions. The one-lung ventilation using double-lumen left-side tube provides better operating field visualization than ventilation throw single-lumen tube with capnothorax. Both techniques supply adequate ventilation and oxygenation parameters. Key words: tracheal intubation, ventilation, pectus excavatum, Nuss procedure
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Hanneman, S. K., G. M. Gusick, S. K. Hamlin, S. J. Wachtel, S. G. Cron, D. J. Jones e S. A. Oldham. "Manual vs Automated Lateral Rotation to Reduce Preventable Pulmonary Complications in Ventilator Patients". American Journal of Critical Care 24, n. 1 (31 dicembre 2014): 24–32. http://dx.doi.org/10.4037/ajcc2015171.
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Kiewkem, T., P. Chaiwiwatworakul e S. Chirarattananon. "Desiccant Dehumidification System for Space Radiant Cooling in Tropical Climate". Advanced Materials Research 622-623 (dicembre 2012): 1575–79. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.1575.
Testo completoAbstract (sommario):
This paper presents an experimental and simulation study on application of a rotating desiccant dehumidification system under a tropical climate. The system was used to dehumidify the ventilation air before supplying to a space where a radiant cooling system was installed to provide thermal comfort. In the study, a computer program of the desiccant system was coded and used to evaluate the system performances. The experimental results show good agreement with the results from coded program. Using the program, the simulation results demonstrate that the desiccant system can reduce and handle the load of the ventilation air. The results also show that in order to remove the whole latent load, the minimum regeneration temperature is 80°C.
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Pakosta, Jiří, e Gabriela Achtenová. "Joint Shaft Test Stand". Journal of Middle European Construction and Design of Cars 15, n. 1 (27 giugno 2017): 11–14. http://dx.doi.org/10.1515/mecdc-2017-0003.
Testo completoAbstract (sommario):
Abstract The article focuses on description of design of the test stand for shafts with universal joints and constant velocity joints. The shafts can be loaded by torque at specified speed of rotation, while retaining the possibility of setting a variable angle between input and output. All shafts are instrumented with contactless signal transmission. In addition, ventilator simulates the cooling derived from the driving speed.
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Lo¨f, George O. G., Gerald Cler e Thomas Brisbane. "Performance of a Solar Desiccant Cooling System". Journal of Solar Energy Engineering 110, n. 3 (1 agosto 1988): 165–71. http://dx.doi.org/10.1115/1.3268252.
Testo completoAbstract (sommario):
A solar desiccant cooling system was operated at the Solar Energy Applications Laboratory, Colorado State University, throughout the 1986 summer. The system comprises an American Solar King fresh air heating/desiccant evaporative cooling unit, a Sunmaster evacuated tube solar collector, hot water solar storage tank, auxiliary electric boiler, controls, and accessories. The cooling unit is operated in the ventilation mode, fresh air being dried in a rotating desiccant matrix, and cooled by heat exchange and evaporative cooling. Return air is used as a cooling medium in a rotating heat exchange matrix, heated by solar energy in a heat exchange coil, and discarded through the rotating desiccant bed. The solar-driven system provided over 90 percent of the seasonal cooling requirements in an experimental, residence type building at average COP levels of 1.0 and solar collection efficiencies of 50 percent when supplied with solar heated water at temperatures of 50 to 65° C. Detailed operating results, including total and average solar cooling provided, coefficients of performance, and overall solar cooling performance ratios are presented.
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He, Qiu Dong, Wen Qi Yu e Shu Fen Xiao. "Impeller Finite Element Analysis of Extractable Explosion-Proof Contra-Rotating Axial Fan for Mine Local Ventilation FBDC". Advanced Materials Research 605-607 (dicembre 2012): 1372–76. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.1372.
Testo completoAbstract (sommario):
To improve the impeller safety and reliability of extractable explosion-proof contra-rotating axial fan for mine local ventilation, Extractable Fan FBDC№9.0/2×30 was taken as the research object, and an approximate three-dimensional finite element computation model was built by using ANSYS software. The stress and displacement were calculated, too. By testing, the fan works stably. The air quantity is 655-978 m3/min, total pressure, 3443-412Pa, static pressure, 3314-118Pa. And the highest static pressure efficiency is up to 70.35%, A-weight Specific Sound Level is 17.5dB. Furthermore, the intension and stiffness of the impeller meet requirements. Sample test and field using show that the computation and the model of this impeller are right. Through reasonable design, the impeller of contra-rotating axial fan with equally-thick circular arc blade profile and ordinary hot-rolling low-carbon steel blades has the intension and the stiffness which meets demands, and the air performance reaches higher level.
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Hubmayr, R. D., J. R. Rodarte, B. J. Walters e F. M. Tonelli. "Regional ventilation during spontaneous breathing and mechanical ventilation in dogs". Journal of Applied Physiology 63, n. 6 (1 dicembre 1987): 2467–75. http://dx.doi.org/10.1152/jappl.1987.63.6.2467.
Testo completoAbstract (sommario):
We evaluated the effects of the different patterns of chest wall deformation that occur with different body positions and modes of breathing on regional lung deformation and ventilation. Using the parenchymal marker technique, we determined regional lung behavior during mechanical ventilation and spontaneous breathing in five anesthetized recumbent dogs. Regional lung behavior was related to the patterns of diaphragm motion estimated from X-ray projection images obtained at functional residual capacity (FRC) and end inspiration. Our results indicate that 1) in the prone and supine positions, FRC was larger during mechanical ventilation than during spontaneous breathing; 2) there were significant differences in the patterns of diaphragm motion and regional ventilation between mechanical ventilation and spontaneous breathing in both body positions; 3) in the supine position only, there was a vertical gradient in lung volume at FRC; 4) in both positions and for both modes of breathing, regional ventilation was nonlinearly related to changes in lobar and overall lung volumes; and 5) different patterns of diaphragm motion caused different sliding motions and differential rotations of upper and lower lobes. Our results are inconsistent with the classic model of regional ventilation, and we conclude that the distribution of ventilation is determined by a complex interaction of lung and chest wall shapes and by the motion of the lobes relative to each other, all of which help to minimize distortion of the lung parenchyma.
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Yamaguchi, Yuzo, Takumi Yoshimizu, Yoshihiro Muta e Mitsuo Tashiro. "A Study on Catheter Drives for Automatic Aspiration Working with Ventilator". Journal of Robotics and Mechatronics 19, n. 3 (20 giugno 2007): 331–38. http://dx.doi.org/10.20965/jrm.2007.p0331.
Testo completoAbstract (sommario):
We developed a catheter drive with two rotors that pinch an aspiration catheter between them and incline along the perpendicular of the catheter axis at mutually opposite angles. Rotors are driven with the same torque in opposite directions to minimize residual torque devolving on the patient being treated. The catheter drive enables a flexible 4 mm diameter plastic catheter to be inserted into and withdrawn from a respiratory cannula over 200 mm long at a constant speed of 30 mm/s accompanying catheter rotation. The catheter drive is about 30 g mass, including a joint to a ventilator and a joint to a vacuum resource for aspiration. Aspiration tests of 5 types of dummy sputum confirmed the feasibility of aspiration by the catheter drive we developed.
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Zhu, Xiaocheng, Wanlai Lin e Zhaohui Du. "Experimental and Numerical Investigation of the Flow Field in the Tip Region of an Axial Ventilation Fan". Journal of Fluids Engineering 127, n. 2 (28 dicembre 2004): 299–307. http://dx.doi.org/10.1115/1.1881654.
Testo completoAbstract (sommario):
The tip leakage flow in an axial ventilation fan with various tip clearances is investigated by experimental measurement and numerical simulation. For a low-rotating-speed ventilation fan with a large tip clearance, both experimental measurement and numerical simulation indicate that the leakage flow originating from the tip clearance along the chord rolls up into a three-dimensional spiral structure to form a leakage flow vortex. The mixing interaction between the tip leakage flow and the main flow produces a low axial velocity region in the tip region, which leads to blockage of the main flow. As the tip clearance increases, the tip leakage flow and the reverse flow become stronger and fully developed. In addition, the position of the first appearance of the tip leakage vortex moves further downstream in a direction parallel to the mid chord line.
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Zhang, Xiaobin, Weibing Zhu, Lei Qian e Miao Li. "Research on Performance Prediction Model of Impeller-Type Breather". Applied Sciences 9, n. 17 (26 agosto 2019): 3504. http://dx.doi.org/10.3390/app9173504.
Testo completoAbstract (sommario):
To investigate the characteristics of separation and resistance of an impeller-type breather in an aeroengine lubrication system, orthogonal test design is used in calculation of the operating condition. Also, phase coupling of the RNG(Renormalization Group) k − ε model and the DPM model (Discrete Phase Model) is used in calculating the selected operating condition. Through analysis of the results, combined with dimensional analysis, it shows the significance of various influencing factors and the optimal level. Based on this, a general formed dimensionless group equation is established for comprehensive separation efficiency, breather separation efficiency, and ventilation resistance. Also, through the least squares method, the performance prediction model of the breather is obtained considering five operating conditions and six structural parameters. The theoretical calculation of separation efficiency and ventilation resistance of an impeller-type breather can be performed. The results show that: the main factors affecting the separation efficiency are the rotating speed and the number of impeller blades; the main factors affecting the ventilation resistance are the ventilation rate and the diameter of the vent hole; the variation trends of the calculated values of the performance prediction model and the experimental values are consistent. The mean error of the comprehensive separation efficiency is 0.97% and the mean error of the ventilation resistance is 11.73%. The calculated values and the experimental values remain consistent, which proves that this performance prediction model can provide references to the assessment and the design of an impeller breather.