Academic literature on the topic 'Reduced airgap'
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Journal articles on the topic "Reduced airgap"
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Eriksson, A. J., B. C. le Roux, H. J. Geldenhuys, and D. V. Meal. "Study of airgap breakdown characteristics under ambient conditions of reduced air density." IEE Proceedings A Physical Science, Measurement and Instrumentation, Management and Education, Reviews 133, no. 8 (1986): 485. http://dx.doi.org/10.1049/ip-a-1.1986.0067.
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Al-Qarni, Ali, and Ayman EL-Refaie. "Magnetic Gears and Magnetically Geared Machines with Reduced Rare-Earth Elements for Vehicle Applications." World Electric Vehicle Journal 12, no. 2 (March 24, 2021): 52. http://dx.doi.org/10.3390/wevj12020052.
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This paper covers a new emerging class of electrical machines, namely, Magnetic Gears (MGs) and Magnetically Geared Machines (MGMs). This particular kind of gears/machines is capable of either scaling up or down the revolutions-per-minute to meet various load profiles as in the case of mechanical gearboxes, but with physical isolation between the rotating components. This physical isolation between the rotational components leads to several advantages in favor of MGs and MGMs over mechanical gearboxes. Although MGs and MGMs can potentially provide a solution for some of the practical issues of mechanical gears, MGs and MGMs have two major challenges that researchers have been trying to address. Those challenges are the high usage of rare-earth Permanent Magnet (PM) materials and the relatively complex mechanical structure of MGs and MGMs, both of which are a consequence of the multi-airgap design. This paper presents designs that reduce the PM rare-earth content for Electric Vehicles (EVs). Additionally, the paper will ensure having practical designs that do not run the risk of permanent demagnetization. The paper will also discuss some new designs to simplify the mechanical structure.
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Liu, Yan, Wenliang Zhao, Xue Fan, Xiuhe Wang, and Byung-il Kwon. "Optimal design of a surface-mounted permanent magnet motor with multi-grade ferrite magnets to reduce torque pulsations." International Journal of Applied Electromagnetics and Mechanics 64, no. 1-4 (December 10, 2020): 79–89. http://dx.doi.org/10.3233/jae-209310.
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This paper proposes an optimal design for a surface-mounted permanent magnet motor (SPMM) to reduce torque pulsations, including cogging torque and torque ripple, by using multi-grade ferrite magnets. Based on a conventional SPMM with single-grade ferrite magnets, the proposed SPMM is designed with four-grade ferrite magnets and then optimized to minimize torque pulsations by maintaining the required torque, utilizing the Kriging method and a genetic algorithm. The results obtained by the finite element analysis show that the optimized SPMM with multi-grade ferrite magnets exhibits improved airgap flux density distribution with highly reduced cogging torque and torque ripple by maintaining the same average torque, as compared to the conventional SPMM. Furthermore, the analysis of the working points for the multi-grade ferrite magnets reveals that the optimized SPMM has good durability against the irreversible demagnetization.
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Ouakad, Hassen M., Nouha Alcheikh, and Mohammad I. Younis. "Static and Dynamic Analysis of Electrostatically Actuated MEMS Shallow Arches for Various Air-Gap Configurations." Micromachines 12, no. 8 (August 5, 2021): 930. http://dx.doi.org/10.3390/mi12080930.
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In this research, we investigate the structural behavior, including the snap-through and pull-in instabilities, of in-plane microelectromechanical COSINE-shaped and electrically actuated clamped-clamped micro-beams resonators. The work examines various electrostatic actuation patterns including uniform and non-uniform parallel-plates airgap arrangements, which offer options to actuate the arches in the opposite and same direction of their curvature. The nonlinear equation of motion of a shallow arch is discretized into a reduced-order model based on the Galerkin’s expansion method, which is then numerically solved. Static responses are examined for various DC electrostatic loads starting from small values to large values near pull-in and snap-through instability ranges, if any. The eigenvalue problem of the micro-beam is solved revealing the variations of the first four natural frequencies as varying the DC load. Various simulations are carried out for several case studies of shallow arches of various geometrical parameters and airgap arrangements, which demonstrate rich and diverse static and dynamic behaviors. Results show few cases with multi-states and hysteresis behaviors where some with only the pull-in instability and others with both snap-through buckling and pull-in instabilities. It is found that the micro-arches behaviors are very sensitive to the electrode’s configuration. The studied configurations reveal different possibilities to control the pull-in and snap-through instabilities, which can be used for improving arches static stroke range as actuators and for realizing wide-range tunable micro-resonators.
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Wang, K., Z. Q. Zhu, and Robert Nilssen. "Using Third Harmonic for Shape Optimization of Flux Density Distribution in Linear Permanent-Magnet Machine." Applied Mechanics and Materials 416-417 (September 2013): 359–65. http://dx.doi.org/10.4028/www.scientific.net/amm.416-417.359.
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This paper presents a sinusoidal permanent magnet (PM) shaping technique with third harmonic to improve the electromagnetic thrust force in linear slotless PM machines without sacrificing the thrust force ripple. Slotless PM linear machine possesses relatively low thrust force ripple due to the absence of cogging force, compared with slotted topology. However, thrust force ripple of the machine with rectangular PM shape still exists due to nonsinusoidal airgap flux density distribution produced by PMs. Sinusoidal shaping techniques can be used to reduce the thrust force ripple but the average thrust force is reduced as well. Therefore, a simple PM shaping technique with optimal 3rd harmonic is presented to improve the output thrust force but not to increase the thrust force ripple. The sinusoidal plus 3rd harmonic shaping technique is analytically demonstrated together conventional sinusoidal shaping method and verified with finite element method. The results show that the electromagnetic performance can be significantly improved.
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Ou, Hu, Mao, and Li. "A Method for Reducing Cogging Torque of Integrated Propulsion Motor." Journal of Marine Science and Engineering 7, no. 7 (July 21, 2019): 236. http://dx.doi.org/10.3390/jmse7070236.
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How to reduce the cogging torque of the integrated propeller motor is an important means to improve its noise performance because cogging torque is one of the key factors causing torque ripple. We proposed a method to reduce the cogging torque by optimizing the size of the Halbach array’s auxiliary pole. First, an analytical model for the airgap magnetic field of Halbach array based on different dimensions (including the circumference ratio and the radial thickness) of the auxiliary pole is given. Then the finite element method is used to verify the analytical model. On the basis, we calculated the cogging torque of different size of auxiliary poles as sample data by combining different circumference ratio and radial thickness. Furthermore, using the two-variable single-objective neural network genetic optimization algorithm based on Backpropagation (BP), we obtain the optimal size of the auxiliary pole. Finally, comparing the motor cogging torque and torque ripple before and after optimization indicated that the cogging torque and torque ripple are effectively reduced after optimizing the size of the auxiliary pole.
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Kim, Kwangsoo. "A Study on Stator Design for Electromagnetic Noise Reduction in Washing Machine Motor." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 6 (April 11, 2021): 585–89. http://dx.doi.org/10.17762/turcomat.v12i6.1999.
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Received:11 november 2020; Accepted: 27 December 2020; Published online: 05 April 2021
Abstract : For low cost, spoke type ferrite magnet motors with small air gap are using to washing machine. At that time, a noise problem occurs, so a design to reduce the noise is required. In the washing machine, set noise increased due to the reduction of air gap of motor at high speed spin mode. Not only the overall noise, but also the harmonics noises are greatly increased at set. As a result of set noise test and noise analysis through finite elements method, a stator tooth shoe shape in which the magnetic flux changes rapidly is cause of noise. Its shape creates many harmonics of load torque. The harmonics component of the load torque increases the overall noise of the set. The harmonics noise of the set has a large correlation with radial force component as well as the torque ripple. Especially, it is found that the harmonics noise of the set is related to harmonics component of load torque and the harmonics component of the radial force at stator tooth. The noise is reduced by applying the new design of stator tooth shoe that can minimize the change in magnetic flux through the noise cause analysis. Through this research, the harmonics noise as well as overall noise are reduced at small airgap motor. Therefore, it is possible to develop cost reduction motor for washing machine.
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Faßbender, Heike, and Julius Mayer. "A revised moment error expression for the AIRGA algorithm." Analele Universitatii "Ovidius" Constanta - Seria Matematica 26, no. 2 (July 1, 2018): 87–104. http://dx.doi.org/10.2478/auom-2018-0020.
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Abstract The fully adaptive rational global Arnoldi method (AIRGA) for the modelorder reduction of second-order multi-input multi-output systems with proportional damping is revisited. The method automatically generates a reduced system approximating the transfer function. It is based on a moment-matching approach. The expansion points are determined iteratively. The reduced order and the number of moments matched per expansion point are determined adaptively using a heuristic based on an error estimation. A revised moment error expression is presented as well as some related findings.
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Shin, Hye-Won, David A. Shelley, Edward M. Henderson, Anne Fitzpatrick, Benjamin Gaston, and Steven C. George. "Airway nitric oxide release is reduced after PBS inhalation in asthma." Journal of Applied Physiology 102, no. 3 (March 2007): 1028–33. http://dx.doi.org/10.1152/japplphysiol.01012.2006.
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Exhaled nitric oxide (NO) is elevated in asthma, but the underlying mechanisms remain poorly understood. Recent results in subjects with asthma have reported a decrease in exhaled breath pH and ammonia, as well as altered expression and activity of glutaminase in both alveolar and airway epithelial cells. This suggests that pH-dependent nitrite conversion to NO may be a source of exhaled NO in the asthmatic airway epithelium. However, the anatomic location (i.e., airway or alveolar region) of this pH-dependent NO release has not been investigated and could impact potential therapeutic strategies. We quantified airway (proximal) and alveolar (peripheral) contributions to exhaled NO at baseline and then after PBS inhalation in stable (mild-intermittent to severe) asthmatic subjects (20–44 yr old; n = 9) and healthy controls (22–41 yr old; n = 6). The mean (SD) maximum airway wall flux (pl/s) and alveolar concentration (ppb) at baseline in asthma subjects and healthy controls was 2,530 (2,572) and 5.42 (7.31) and 1,703 (1,567) and 1.88 (1.29), respectively. Compared with baseline, there is a significant decrease in the airway wall flux of NO in asthma as early as 15 min and continuing for up to 60 min (maximum −28% at 45 min) after PBS inhalation without alteration of alveolar concentration. Healthy control subjects did not display any changes in exhaled NO. We conclude that elevated airway NO at baseline in asthma is reduced by inhaled PBS. Thus airway NO may be, in part, due to nitrite conversion to NO and is consistent with airway pH dysregulation in asthma.
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Lim, Dae Hyun, Jae Youn Cho, Marina Miller, Kirsti McElwain, Shauna McElwain, and David H. Broide. "Reduced peribronchial fibrosis in allergen-challenged MMP-9-deficient mice." American Journal of Physiology-Lung Cellular and Molecular Physiology 291, no. 2 (August 2006): L265—L271. http://dx.doi.org/10.1152/ajplung.00305.2005.
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Matrix metalloproteinases (MMPs) are a family of extracellular proteases that are responsible for the degradation of the extracellular matrix during tissue remodeling. We have used a mouse model of allergen-induced airway remodeling to determine whether MMP-9 plays a role in airway remodeling. MMP-9-deficient and wild-type (WT) mice were repetitively challenged intranasally with ovalbumin (OVA) antigen to develop features of airway remodeling including peribronchial fibrosis and increased thickness of the peribronchial smooth muscle layer. OVA-challenged MMP-9-deficient mice had less peribronchial fibrosis and total lung collagen compared with OVA-challenged WT mice. There was no reduction in mucus expression, smooth muscle thickness, or airway responsiveness in OVA-challenged MMP-9-deficient compared with OVA-challenged WT mice. OVA-challenged MMP-9-deficient mice had reduced levels of bronchoalveolar lavage (BAL) regulated on activation, normal T cell expressed, and secreted (RANTES), as well as reduced numbers of BAL and peribronchial eosinophils compared with OVA-challenged WT mice. There were no significant difference in levels of BAL eotaxin, thymus- and activation-regulated chemokine (TARC), or macrophage-derived chemokine (MDC) in OVA-challenged WT compared with MMP-9-deficient mice. Overall, this study demonstrates that MMP-9 may play a role in mediating selected aspects of allergen-induced airway remodeling (i.e., modest reduction in levels of peribronchial fibrosis) but does not play a significant role in mucus expression, smooth muscle thickness, or airway responsiveness.
Dissertations / Theses on the topic "Reduced airgap"
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Dumas, Florian. "Contribution à l'étude des machines polyentrefers à aimants permanents et à entrefer réduit.Applications aux machines à flux axial à hautes performances sous contrainte d'encombrement." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20151.
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Cette thèse porte sur l'étude de machines polyentrefers et leurs limitations, dans le contexte d'avion plus électrique et du projet de déplacement des avions au sol. Ces moteurs, basés sur l'utilisation de plusieurs éléments mobiles et fixes mis en parallèle, permettent d'obtenir de hautes performances. Une étude sur les tolérances des dimensions des éléments actifs montre que les performances peuvent être dégradées si des précautions lors de la réalisation ne sont pas prises et si les entrefers utilisés ne sont pas faibles. Ce manuscrit présente un système totalement innovant permettant d'utiliser un entrefer réduit à son minimum sans que les performances ne soient dégradées par de la friction. Ce système est appelé système de compensation des efforts de plaquage. Afin de développer un moteur tournant à entraînement direct dans le cadre du taxiage des avions, deux topologies différentes de machines discoïdes sont étudiées et dimensionnées. Les résultats favorisent l'utilisation d'une des deux structures, à entrefer réduit, pour réaliser un maximum de couple dans le volume donné. Afin de prouver la faisabilité du système innovant sur un moteur discoïde, la réalisation d'un prototype laboratoire complet est proposée. Des simulations thermiques et du comportement du système innovant permettront de valider ces étudesThis thesis focuses on the study of multi-air gap machines and their limitations, in the framework of more electric aircraft and the project of moving aircrafts on the ground without the main engines. These motors, based on the use of mobile and fixed parts disposed in parallel, induce high performance. A study concerning the tolerance for the dimensions of active parts shows that performance can decrease if precautions are not taken during manufacturing and if the air gaps are not small. This manuscript presents a totally innovative system that permits the use of an air gap reduced to its minimum without reducing performance by friction. This system is called system of attraction control. In order to develop a direct-drive motor for aircraft taxiing, two different topologies of disc-type machines are studied and sized. The obtained results encourage the use of one of the two structures with reduced air gap to realize maximum torque in the fixed volume. To prove the feasibility of the innovative system on a disc-type motor, the conception of an entire laboratory prototype is proposed. Thermal modelling and simulations on the innovative system behaviour will validate the presented work
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Oguma, Tetsuya, Hiroaki Kume, Satoru Ito, Naoya Takeda, Haruo Honjo, Itsuo Kodama, Kaoru Shimokata, Kaichiro Kamiya, and 香一郎 神谷. "Involvement of reduced sensitivity to Ca2+ in b-adrenergic action on airway smooth muscle." Blackwell Scientific Publication, 2006. http://hdl.handle.net/2237/2750.
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Liang, Huang-ju, and 梁皇如. "Do reinforcements of tobacco control reduce medical utilization for airway diseases?" Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7uu9u5.
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碩士國立臺北護理健康大學
健康事業管理研究所
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Background and Objective: The World Health Organization (WHO) estimated annual 600,000 mortality cases due to second-hand tobacco smoke-related diseases, such as heart diseases, respiratory tract diseases, and cancer. Respiratory tract diseases, mainly chronic obstructive pulmonary disease (COPD) and asthma, have become progressively prevalent with increasing costs in the past years in the Asia-Pacific region. In Europe and America, reports demonstrated that smoke-free legislation in public places and restaurants have significantly reduced the hospitalization rate and mortality rate of COPD and asthma. However, no study examined the second stage of smoke-free legislation on ambulatory and emergency visits for COPD and asthma. Materials and Methods: We collected and analyzed the data on ambulatory care expenditures by visits (CD), and registry for contracted medical facilities (HOSB) files between 2005 and 2013 from the National Health Insurance Research Databases (NHIRD) of Taiwan. We applied Poisson regression analysis to assess the relative risk of ambulatory and emergency visits of patients with COPD or asthma following the second stage of smoke-free legislation. Results: The implementation of the second stage of smoke-free legislation was associated with a significant reduction in ambulatory visits, but no reduction of emergency visits, in patients with asthma. In patients with COPD, both ambulatory and emergency visits were not reduced. The penalty for smoke ban violations was associated with a significant reduction in ambulatory and emergency visits for asthma and COPD. Discussion: We provided an overall analysis of the medical utilization of asthma and COPD from the analysis of a population-based database. Future studies, such as the use of the patient medical database, and the inclusion of disease severity, lung function, and the use of questionnaires to obtain personal smoking history and exposure to secondhand smoke, will provide more understanding of the individual profile of the disease. Conclusions: Second-hand smoke exposure has been decreasing, and there is a significant reduction in the risk of outpatients with asthma. The facts that smoke-free legislation does not cover families and 60% emergency visits in our study were young individuals might explain the lack of reduction in emergency visits for asthma. In patients with COPD, both ambulatory and emergency visits did not decrease significantly. Since the elderly individuals, who had left their workplaces, accounted for more than 90% of those visits in our study for COPD, workplace factors which could be affected by smoke-free legislation may not play a significant role. The implementation of non-compliance penalty for smoking and higher penalty are associated with a significant reduction in the relative risk of outpatients and emergency visits in patients with asthma and COPD.
Books on the topic "Reduced airgap"
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Randerath, Winfried J., and Shahrokh Javaheri. Sleep and the heart. Edited by Sudhansu Chokroverty, Luigi Ferini-Strambi, and Christopher Kennard. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199682003.003.0040.
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Heart function and sleep are closely associated. While NREM sleep reduces cardiac workload, phasic REM sleep increases sympathetic activity and cardiac vulnerability. Heart failure (HF) patients suffer from disturbed sleep due to frequent awakenings, periodic limb movements, sleep apnea, and depression. Insomnia seems to be associated with incident HF, and, when comorbid, results in a vicious circle. There is much evidence of a relationship between breathing disturbances during sleep and heart diseases. At least 50% of HF patients suffer from obstructive (OSA) or central (CSA) sleep apnea, both associated with impaired prognosis. OSA is a risk factor for arterial hypertension, atrial fibrillation, and HF. Continuous positive airway pressure devices reduce adverse cardiac events and improve outcome in severe OSA in compliant subjects. Adaptive servoventilation (ASV) is superior to other therapeutic options for CSA. However, the use of ASV is contraindicated in severe HF with reduced, but not preserved, ejection fraction.
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Phillips, Dennis, and Joshua Knight. The Difficult Airway (DRAFT). Edited by Raghavan Murugan and Joseph M. Darby. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190612474.003.0018.
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The difficult airway invariably presents itself to all airway managers and is mostly unpredictable in the context of rapid response team (RRT) calls. A multiprofessional difficult airway team (DAT) that could be called for airway emergencies is likely to reduce complications and death. The DAT is organized with predefined roles for each member so that rapid intervention occurs during the emergency. Priority is given to oxygenation throughout the airway response. The anticipated and unanticipated difficult airways should be approached differently and often require medication adjuncts that should be carefully chosen. Airway devices such as the video laryngoscope and the laryngeal mask airway (LMA) have dramatically improved the ability to secure an airway quickly. Finally, it is important to recognize when a surgical airway is needed in the setting of the RRT calls.
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Pevernagie, Dirk. Positive airway pressure therapy. Edited by Sudhansu Chokroverty, Luigi Ferini-Strambi, and Christopher Kennard. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199682003.003.0017.
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This chapter describes positive airway pressure (PAP) therapy for sleep disordered breathing. Continuous PAP (CPAP) acts as a mechanical splint on the upper airway and is the treatment of choice for moderate to severe obstructive sleep apnea (OSA). Autotitrating CPAP may be used when the pressure demand for stabilizing the upper airway is quite variable. In other cases, fixed CPAP is sufficient. There is robust evidence that CPAP reduces the symptomatic burden and risk of cardiovascular comorbidity in patients with moderate to severe OSA. Bilevel PAP is indicated for treatment of respiratory diseases characterized by chronic alveolar hypoventilation, which typically deteriorates during sleep. Adaptive servo-ventilation is a mode of bilevel PAP used to treat Cheyne–Stokes respiration with central sleep apnea . It is crucial that caregivers help patients get used to and be compliant with PAP therapy. Education, support, and resolution of adverse effects are mandatory for therapeutic success.
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Hjoberg, Josephine. The Hyperosmolar Airway: Mechanisms of Reduced Response to Nitric Oxide (Comprehensive Summaries of Uppsala Dissertations, 879). Uppsala Universitet, 1999.
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Mushambi, Mary C., and Rajesh Pandey. Management of the difficult airway. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198713333.003.0026.
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Failed or difficult intubation is still a major cause of maternal morbidity and mortality. The management of the airway in the pregnant patient requires careful consideration of anatomical and physiological changes, training issues, and situational factors. Despite significant improvements in monitoring and airway equipment, and a reduction in anaesthetic-related maternal mortality, the incidence of failed intubation in the pregnant woman in many units has remained between 1/250 and 1/300. This may result from many factors such as the reduction of the number of caesarean deliveries performed under general anaesthesia which has resulted in limited opportunities to teach airway skills in obstetrics, the increased incidence of obesity, and the rise in maternal age and associated co-morbidities. Improved training and careful planning and performance of a general anaesthetic (i.e. reducing the risk of aspiration; optimum pre-oxygenation, patient positioning, and application of cricoid pressure; and availability of appropriate airway equipment) have the potential to reduce airway-related morbidity and mortality in the pregnant woman. Simple bedside tests such as Mallampati scoring, thyromental distance, neck movement, and ability to protrude the mandible may help to predict a potential difficult airway, particularly when used in combination. Management of a predicted difficult airway requires early referral to the anaesthetists, formulation of an airway management strategy, and involvement of the multidisciplinary team in decision-making. Fibreoptic equipment and skills should be readily available when required. Management of the unpredicted difficult airway should make maintenance of maternal and fetal oxygenation the primary goal. Decision-making during a failed intubation on whether to proceed or wake the patient should involve the obstetrician and ideally be planned in advance. The periods during extubation and recovery are high risk and require preparation and planning in advance.
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Marini, John J., and Paolo Formenti. Pathophysiology and prevention of sputum retention. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0119.
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Retention of airway mucus is one of the major problem that confronts post-operative and critically-ill patients, as well as the caregivers that address it. Retained secretions increase the work of breathing and promote hypoxaemia, atelectasis, and pneumonia. The airway-intubated patient is at particular risk of retaining mucus, as the presence of the tube interrupts normal flow of airway secretions toward the larynx by the mucociliary escalator and coughing effectiveness is degraded by a glottis that is stented open and cannot close effectively. Clearance of mucus is aided by using sufficient gas stream and total body hydration to reduce sputum viscosity and lubricate secretion plugs. Airway suctioning, a routine, but inherently traumatic experience for the patient, may clear the central airway, but leave peripheral airways unrelieved of their secretion burden. Prone positioning appears to confer an advantage regarding secretion drainage and clearance. Physiotherapy techniques may be useful in re-establishing and maintaining airway patency.
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Hedenstierna, Göran, and Hans Ulrich Rothen. Physiology of positive-pressure ventilation. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0088.
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During positive pressure ventilation the lung volume is reduced because of loss of respiratory muscle tone. This promotes airway closure that occurs in dependent lung regions. Gas absorption behind the closed airway results sooner or later in atelectasis depending on the inspired oxygen concentration. The elevated airway and alveolar pressures squeeze blood flow down the lung so that a ventilation/perfusion mismatch ensues with more ventilation going to the upper lung regions and more perfusion going to the lower, dependent lung. Positive pressure ventilation may impede the return of venous blood to the thorax and right heart. This raises venous pressure, causing an increase in systemic capillary pressure with increased capillary leakage and possible oedema formation in peripheral organs. Steps that can be taken to counter the negative effects of mechanical ventilation include an increase in lung volume by recruitment of collapsed lung and an appropriate positive end-expiratory pressure, to keep aerated lung open and to prevent cyclic airway closure. Maintaining normo- or hypervolaemia to make the pulmonary circulation less vulnerable to increased airway and alveolar pressures, and preserving or mimicking spontaneous breaths, in addition to the mechanical breaths, since they may improve matching of ventilation and blood flow, may increase venous return and decrease systemic organ oedema formation (however, risk of respiratory muscle fatigue, and even overexpansion of lung if uncontrolled).
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Muders, Thomas, and Christian Putensen. Pressure-controlled mechanical ventilation. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0096.
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Beside reduction in tidal volume limiting peak airway pressure minimizes the risk for ventilator-associated-lung-injury in patients with acute respiratory distress syndrome. Pressure-controlled, time-cycled ventilation (PCV) enables the physician to keep airway pressures under strict limits by presetting inspiratory and expiratory pressures, and cycle times. PCV results in a square-waved airway pressure and a decelerating inspiratory gas flow holding the alveoli inflated for the preset time. Preset pressures and cycle times, and respiratory system mechanics affect alveolar and intrinsic positive end-expiratory (PEEPi) pressures, tidal volume, total minute, and alveolar ventilation. When compared with flow-controlled, time-cycled (‘volume-controlled’) ventilation, PCV results in reduced peak airway pressures, but higher mean airway. Homogeneity of regional peak alveolar pressure distribution within the lung is improved. However, no consistent data exist, showing PCV to improve patient outcome. During inverse ratio ventilation (IRV) elongation of inspiratory time increases mean airway pressure and enables full lung inflation, whereas shortening expiratory time causes incomplete lung emptying and increased PEEPi. Both mechanisms increase mean alveolar and transpulmonary pressures, and may thereby improve lung recruitment and gas exchange. However, when compared with conventional mechanical ventilation using an increased external PEEP to reach the same magnitude of total PEEP as that produced intrinsically by IRV, IRV has no advantage. Airway pressure release ventilation (APRV) provides a PCV-like squared pressure pattern by time-cycled switches between two continuous positive airway pressure levels, while allowing unrestricted spontaneous breathing in any ventilatory phase. Maintaining spontaneous breathing with APRV is associated with recruitment and improved ventilation of dependent lung areas, improved ventilation-perfusion matching, cardiac output, oxygenation, and oxygen delivery, whereas need for sedation, vasopressors, and inotropic agents and duration of ventilator support decreases.
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Mojoli, Francesco, and Antonio Braschi. Respiratory support with continuous positive airways pressure. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0089.
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Continuous positive airways pressure (CPAP) is a mechanical ventilation (MV) mode in which the patient breaths spontaneously at a higher than atmospheric pressure. CPAP increases transpulmonary pressure inducing an FRC increase and a WOB decrease in acute restrictive lung pathology, with improvement of gas exchange. The work of breathing (WOB) is also reduced in the resistive component and inspiratory effort can be reduced if the patient experiences airway collapse and flow limitation, where CPAP counteracts the inspiratory threshold load represented by intrinsic PEEP. CPAP has been proven to be useful in many clinical situation and the technique for administration has a pivotal role in clinical efficacy of the technique. It’s crucial to keep the positive pressure as constant as possible and to avoid any technical increase of WOB. These goals can be achieved by continuous or demand flow systems. The modern ventilators work well and have overcome the valve function problem, which made difficult to use CPAP with old-generation machines.
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Kriemler, Susi, Thomas Radtke, and Helge Hebestreit. Exercise, physical activity, and cystic fibrosis. Edited by Neil Armstrong and Willem van Mechelen. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198757672.003.0027.
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Cystic fibrosis (CF) is a genetic disease resulting in an impaired mucociliary clearance, chronic bacterial airway infection, and inflammation. The progressive destruction of the lungs is the main cause of morbidity and premature death. Diverse other organ systems such as heart, muscles, bones, gastro-intestinal tract, and sweat glands are often also affected and interfere with exercise capacity. Hence, exercise capacity is reduced as the disease progresses mainly due to reduced functioning of the muscles, heart, and/or lungs. Although there is still growing evidence of positive effects of exercise training in CF on exercise capacity, decline of pulmonary function, and health-related quality of life, the observed effects are encouraging and exercise should be implemented in all patient care. More research is needed to understand pathophysiological mechanisms of exercise limitations and to find optimal exercise modalities to slow down disease progression, predict long-term adherence, and improve health-related quality of life.
Book chapters on the topic "Reduced airgap"
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Jacob, Rebecca, Subramanyam S. Mahankali, Renita Maria, Suman Ananathanarayana, Garima Sharma, and Mary Thomas. "Anaesthesia for Maxillo Facial Surgery." In Oral and Maxillofacial Surgery for the Clinician, 95–117. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-1346-6_7.
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AbstractMaxillofacial surgery presents unique challenges to the anaesthesiologist. The main challenges include working with multiple professionals; managing a shared airway; ensuring good surgical access; identifying difficult airway and choosing an appropriate airway management technique perioperatively; using measures to reduce bleeding and tissue oedema. To achieve this effectively and safely, there is a great need for good communication among anaesthesiologists, surgeons and other team members.
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Vermorken, Jan B. "Where and when to Use Induction Chemotherapy in Head and Neck Squamous Cell Cancer." In Critical Issues in Head and Neck Oncology, 155–79. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63234-2_11.
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AbstractThe treatment of locoregionally advanced squamous cell carcinoma of the head and neck (LA-HNSCC) is reviewed, highlighting the milestones in systemic therapy in that setting, with focus on the role of induction chemotherapy (ICT). The road to what is now considered the standard ICT regimen, i.e. the TPF (docetaxel/cisplatin/5-FU) regimen is described, and the differences between the European and the American TPF are discussed. The article describes the respective roles of ICT for larynx preservation, for treatment intensification, its role in patients with borderline resectable or unresectable oral cavity cancer, its role as a selection tool for radiotherapy dose de-escalation in patients with oropharyngeal squamous cell cancer (OPSCC) and its potential future role in strategies aiming at synchronous oligometastatic disease.ICT has an established role for organ preservation in advanced laryngeal and hypopharyngeal cancer and the TPF regimen has been validated in that setting. This approach is presently being compared in a randomized controlled trial to concurrent chemoradiotherapy (CCRT), which in many parts of the world is considered the standard organ preservation procedure. There remains uncertainty about the benefit of the sequential approach of ICT followed by CCRT, despite the fact that ICT significantly reduces the occurrence of distant metastases. It is advised that future studies should include patients who have the highest risk to develop distant metastases, in particular patients with low neck nodes and matted nodes. Moreover, further studies in patients with HPV-associated OPSCC at risk for distant failure (T4 or N3 disease) should be considered for that also. These approaches still need to be confirmed in adequately sized randomized controlled trials. Outside clinical trials, the utility of ICT is restricted to uniquely pragmatic clinical scenarios, such as unavoidable delay in radiation or in the situation that RT is not tolerated or feasible. This can happen when there is severe pain from advanced disease or there is impending airway compromise or neurologic dysfunction that necessitates rapid initiation of treatment. In all those circumstances whether within the context of trials or outside trials, it is imperative that the present backbone of ICT, the TPF regimen, is being administered by experienced oncologists, familiar with the necessary protocols and supportive care requirements to ensure patient safety and maximize adherence throughout the treatment.Future areas of research are the role of ICT in strategies whereby ICT is combined with upfront metastases-directed treatments and the usefulness of targeted agents or immune checkpoint inhibitors in the induction setting. Studies in that direction have already started. Finally, the application of radiographic, proteomic and genomic biomarkers will get attention to further define prognostic groups and guide treatment selection with greater precision.
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Woehrle, Holger, and Michael Arzt. "Sleep apnoea: treatment options and sleep/cardiovascular outcome." In ESC CardioMed, 1065–69. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0258.
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In addition to lifestyle interventions, treatments for obstructive sleep apnoea focus on maintaining upper airway patency. Continuous positive airway pressure (CPAP) is recommended as first-line therapy. Beneficial cardiovascular effects of CPAP include increased intrathoracic pressure, reduced left ventricular preload and afterload, and reduced transmural cardiac pressure gradients. CPAP also reduces nocturnal ischaemia and blood pressure, and decreases the risk of post-treatment atrial fibrillation recurrence. However, secondary prevention with CPAP did not significantly reduce the rate of major cardio- and cerebrovascular events in the SAVE study. Mandibular advancement devices, surgery, and upper airway stimulation are options for patients unwilling to use or tolerate CPAP. Central sleep apnoea and Cheyne–Stokes respiration are common in patients with heart disease, especially heart failure. Adaptive servo-ventilation is the most effective therapy for alleviating central sleep apnoea with Cheyne–Stokes respiration. However, it is now contraindicated in heart failure patients with an ejection fraction of 45% or lower and predominant central sleep apnoea because of an increased risk of cardiovascular death, based on SERVE-HF study results. However, adaptive servo-ventilation may still have a role in other settings, including heart failure with preserved ejection fraction. Phrenic nerve stimulation is a new treatment modality that has shown promising results in a feasibility study. Hypoventilation is another breathing disorder that needs effective management. Data in cardiovascular disease are lacking, but CPAP and non-invasive ventilation have been shown to be effective in patients with obesity hypoventilation syndrome. Furthermore, effective reduction of chronic hypercapnia during home non-invasive ventilation treatment in patients with chronic obstructive pulmonary disease has been shown to significantly improve survival.
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"Strategies to Reduce Excessive Mucus Secretion in Airway Inflammation." In Therapeutic Targets in Airway Inflammation, 962–89. CRC Press, 2003. http://dx.doi.org/10.3109/9780203911471-48.
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"Respiratory physiotherapy." In Emergencies in Respiratory Medicine, edited by Robert Parker, Catherine Thomas, and Lesley Bennett, 301–6. Oxford University Press, 2007. http://dx.doi.org/10.1093/med/9780199202447.003.0050.
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Airway clearance techniques 302 Indications for physiotherapy 303 On-call physiotherapy services 305 Respiratory physiotherapy (PT) is indicated in specific acute situations to facilitate secretion clearance, reduce airflow obstruction and improve ventilation. This is achieved using a variety of airway clearance techniques. Several airway clearance techniques (ACTs) are available and can be used alone or in combination according to the clinical situation....
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Stradling, J. R., and S. E. Craig. "Upper airways obstruction." In Oxford Textbook of Medicine, 3254–60. Oxford University Press, 2010. http://dx.doi.org/10.1093/med/9780199204854.003.180501.
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At resting levels of ventilation, the main airway can be reduced to a diameter of 3 mm or so before respiratory distress and stridor occur. Little more narrowing is required to precipitate complete asphyxia, hence when upper airways obstruction is suspected, assessment of severity, diagnosis, and treatment is a medical emergency....
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Ballard, Heather, Michelle Tsao, and Narasimhan Jagannathan. "Fiberoptic, Video Laryngoscope, and Nasal Airway Procedures." In Pediatric Anesthesia Procedures, edited by Anna Clebone and Barbara K. Burian, 37–60. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780190685188.003.0003.
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In patients with known or suspected difficult airways, advanced airway procedures such as fiberoptic laryngoscopy (under general anesthesia—with and without supraglottic airways—and sometimes in awake patients) as well as video laryngoscopy are invaluable. All may be particularly advantageous for use with patients who have limited or reduced cervical spine movement. Other advantages and disadvantages are addressed in this chapter. Techniques for nasotracheal intubation are also described. Flexible fiberoptic laryngoscopy is a means of indirectly visualizing airway structures by threading a fiberoptic scope with a camera at the end of the scope into the airway. The goal of fiberoptic laryngoscopy is endotracheal intubation using a Seldinger technique, whereby an endotracheal tube is guided into the trachea over the fiberoptic bronchoscope. Fiberoptic endotracheal intubation may be performed through the mouth or nose, or through a supraglottic airway (SGA). The use of the fiberoptic scope through an SGA is an especially useful technique in infants who suffer from airway obstruction at rest (e.g., infants with Pierre Robin syndrome). Video laryngoscopy employs a laryngoscope with a camera at the end of the blade to enable the user to indirectly visualize airway structures.
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Engelhardt, Thomas. "System-based anatomy and physiology." In Paediatric Anaesthesia, 3–22. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780198755791.003.0001.
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Children who undergo general anaesthesia have an increased perioperative risk of morbidity and mortality compared with adults. This is due to differences in anatomy and reduced physiological reserves. A clear understanding of neonatal and paediatric anatomy and physiology is therefore essential to provide safe paediatric perioperative care. This chapter outlines major anatomical and physiological differences of the paediatric and neonatal airway, including causes and treatment of airway obstruction. Essential aspects of the respiratory, cardiovascular, CNS, and hepatorenal systems are discussed. Important considerations of fluid and thermal control are described that form the basis of safe paediatric anaesthesia practice.
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Warner, Mark A. "Perioperative Positioning Injuries." In Mayo Clinic Atlas of Regional Anesthesia and Ultrasound-Guided Nerve Blockade, 39–48. Oxford University Press, 2010. http://dx.doi.org/10.1093/med/9780199743032.003.0004.
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Positioning-related injuries such as central and peripheral neuropathies, compartment syndromes, and soft-tissue injury can be reduced by considering preoperative and intraoperative factors. Preoperative considerations include normal joint range of motion, body habitus, and health status. Intraoperative considerations include compression by table attachments, duration of surgery, airway management, and use of pads and supports.
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Motz, Kevin, and Susheel P. Patil. "The Prevalence and Impact of Obstructive Sleep Apnea and Current Management Landscape." In Upper Airway Stimulation Therapy for Obstructive Sleep Apnea, 5–26. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780197521625.003.0002.
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Obstructive sleep apnea (OSA) is characterized by repeated collapse of the upper airway during sleep that leads to reduced airflow and oxyhemoglobin desaturation. The disorder is highly prevalent, with obesity, male sex, and increasing age as risk factors. Consequences of untreated OSA include neurocognitive impairment, such as excessive daytime sleepiness, and an increased risk of cardiovascular and cerebrovascular disease. Positive airway pressure therapy remains the most common treatment for OSA. Over the last few decades, alternative nonsurgical and surgical treatments have been developed. Although surgical approaches are rarely curative, careful patient selection may benefit a subpopulation of people living with OSA. Selective hypoglossal nerve stimulation represents a new treatment strategy for the management of OSA in selected patients.
Conference papers on the topic "Reduced airgap"
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Rijken, Oriol. "Installation Methodologies for a Tension Leg Platform Under Ocean Swell Conditions." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11381.
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A common procedure of installing a Tension Leg Platform is to float it over the tendons and lower it over the tendons. A key phase of this procedure is lock-off, i.e. the instant when the tendons become firmly attached to the TLP hull. The lock-off position of the tendons on the hull should be within specified tolerances. Lock-off on the tendons higher than targeted results in a reduced draft which implies reduced displacement and therefore typically reduced payload capacity or reduced payload reserve. Lock-off on the tendons lower than targeted results in increase in draft and brings the deck closer to mean water which adversely affects the airgap requirements. Hence lock-off at the correct draft is a key aspect of a successful installation procedure. The general geometric properties of several TLPs are such that there is a significantly more heave motion under swell conditions than under sea states with much smaller peak periods (for the same significant wave height). These larger motions under swell conditions can make it harder to achieve the desired lock-off elevation. Such swell conditions are known to occur of the West Coast of Africa. Waiting for the swell to subside may not be an attractive alternative for TLP installation as these swells may be present for extended periods of time. Two engineering solutions are provided which reduce the heave motion of a free floating TLP. Both of these solutions are temporary changes to the TLP itself and should be implemented as a part of the TLP design spiral. One of the solutions implies an increase of TLP mass; the second solution reduces the vertical stiffness of the free floating TLP. The heave natural period is significantly increased in both methods, and heave motions are reduced. Both methods increase the heave response amplitude operator (RAO) for periods below 8 to 12 seconds and reduce the heave RAO magnitudes above 12 seconds. Implementing one of these methods in the installation procedure may be most applicable to situations where the installation window may contain prolonged periods of persistent swell.
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Buchner, Bas, and Arjan Voogt. "Wave Slamming on External Turrets of FPSOs." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79581.
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The paper discussed the possible slamming loads on the underside of the (chaintable of) external turret moored F(P)SOs. For this problem of turret slamming, a combined exceedance of the airgap between the underside of the chaintable and the relative wave is needed, as well as a certain relative wave velocity. A model test series was carried out to determine these loads on a typical external turret. The model test results provide insight into the complex loading process of external turret type structures. A clear quadratic relation between submergence velocity and impact load, as typically observed for slamming problems, has not been identified. This is probably a result of local effects, such as the strong disturbance of the free surface (giving a locally different deadrise angle) and air entrapment effects. The maximum pressure on the conical turret (chain table) is significantly reduced compared to the flat turret, which was expected based on the reduced rate of change of momentum with the conical turret. Based on linear 3D diffraction analysis and the empirical relations derived from the model tests, a method is presented to determine first design estimates of the pressures.
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Hwang, Sangmoon, and Dennis K. Lieu. "Characterization and Reduction of Reluctance Torque in Permanent Magnet D.C. Motors." In ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0237.
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Abstract For motors with low speeds and loads, torque pulsation by the reluctance torque is an important source of vibration and control difficulty. In this paper, the magnetic field of a motor is calculated by finite element method and the periodic reluctance torque is determined using Maxwell stress method and time stepping method, and then decomposed using Fourier series expansion. The purpose of this paper is to characterize design parameters on the reluctance torque and to design a permanent magnet motor with a reluctance torque less vulnerable to vibration, without sacrificing the motor performance. The design parameters include stator slot width, permanent magnet slot width, airgap length and magnetization direction. A new design with a less populated frequency spectrum of the reluctance torque is proposed after characterizing individual effect of design parameters. Gradual magnetization, by gradually increasing the thickness of the permanent magnets at edges, yields a smooth shape for the reluctance torque with reduced harmonics.
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Frieder, Russell, and Sri Kumar. "Biomechanical Analysis of Late Airbag Deployment in Motor Vehicle Crashes Using Computer Simulation." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176654.
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Motor vehicle collisions frequently result in serious or fatal inuries to occupants [1–4]. Frontal collisions are amongst the most severe types of accidents. The use of safety systems such as seat belts and airbags has been shown to reduce the severity of injuries sustained by occupants [5–10]. It is well known that frontal airbags act as supplemental restraints to seat belts in protecting occupants. Airbag deployment occurs through a reaction of chemicals in the inflator that rapidly produces gas and fills the canvas bag. The filled bag acts a cushion between the occupant and the vehicle’s interior components. The supplemental restraint provided by the airbag increases the amount of time and distance over which the occupant’s body decelerates, and accordingly reduces the potential for injury. The time at which the airbag deployment is initiated during the crash sequence can have an effect on the nature of the contact between occupant and airbag. Though properly timed, frontal airbags have been shown to reduce injuries sustained to occupants[11], it has been reported that airbags that deploy too late may cause injury[12]. To date, there have been a very limited number of studies that have addressed the biomechanical effects of late airbag deployment. The purpose of this study is to determine the biomechanical effects of late airbag deployment and restraint use on various sizes of occupants through computer simulation.
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Kermode, Jessica A., David G. Chapman, Nathan J. Brown, Norbert Berend, Gregory G. King, and Cheryl M. Salome. "Reduced Airway Distensibility Is Not Associated With Airway Re-Narrowing Following Deep Inspiration." In American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado. American Thoracic Society, 2011. http://dx.doi.org/10.1164/ajrccm-conference.2011.183.1_meetingabstracts.a2184.
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Wang, Kimberley, Timothy Le Cras, Alexander Larcombe, Graeme Zosky, Alan James, and Peter Noble. "Transforming growth factor alpha produces airway remodelling and reduces airway distensibility." In ERS International Congress 2017 abstracts. European Respiratory Society, 2017. http://dx.doi.org/10.1183/1393003.congress-2017.pa386.
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Zeki, A. A., R. A. Lu, X. Ai, K. Chmiel, R. Krishnan, and C. Ghosh. "Inhaled Pitavastatin Reduces Airway Smooth Muscle Contraction." In American Thoracic Society 2019 International Conference, May 17-22, 2019 - Dallas, TX. American Thoracic Society, 2019. http://dx.doi.org/10.1164/ajrccm-conference.2019.199.1_meetingabstracts.a2840.
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Shih, Tzu-Ching, Tzyy-Leng Horng, and Fong-Lin Chen. "Computational Fluid Dynamics Analysis of Pressure Drop Alteration in the Trachea Before and After Vascular Ring Surgery." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63933.
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The purpose of this study is to apply the computational fluid dynamics (CFD) technique to evaluate the tracheal airway pressure change before and after the vascular ring surgery (VRS) based on patient computed tomography (CT) images. Computer simulation results also show that after a surgical treatment the pressure drop in the tracheal airway was significantly decreased, especially for low inspiratory and expiratory velocities. In other words, the flow resistance in the tracheal airway becomes decreased after the VRS when the airway is expanded. The airway flow resistance of tracheal stenosis caused by CVR can be augmented by increased air flow velocity. Numerical results show that the pressure drop in the tracheal airway was 0.1099 Pa for the inlet inspiratory velocity of 10 cm/s before the VRS. After the VRS, the pressure drop was reduced and became 0.0598 Pa. In the meantime, the improvement gain was 45.58%. In word words, the pressure drop was reduced after the vascular ring surgery. Therefore, the CFD approach can be a useful method for quantifying the change of airway resistance and evaluating the effectiveness of relief of tracheal stenosis by the VRS.
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Lee, Y. G., C. S. Yu, P. W. Green, L. D. Chen, and P. B. Butler. "A Study of Aspiration Effects in Reduced-Scale Model Airbag Modules." In International Body Engineering Conference & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1998. http://dx.doi.org/10.4271/982324.
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Benton, Angela S., Alan M. Watson, Jesse Damsker, Erica Reeves, Mary C. Rose, Eric P. Hoffman, and Robert J. Freishtat. "Synchronizing Mitosis Reduces Intrinsic Inflammation In Asthmatic Airway Epithelium." In American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado. American Thoracic Society, 2011. http://dx.doi.org/10.1164/ajrccm-conference.2011.183.1_meetingabstracts.a2814.
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