Academic literature on the topic 'Net pressure ratio'
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Journal articles on the topic "Net pressure ratio"
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Zivic, Marija, Antun Galovic, and Zdravko Virag. "Detailed analysis of the effect of the turbine and compressor isentropic efficiency on the thermal and exergy efficiency of a Brayton cycle." Thermal Science 18, no. 3 (2014): 843–52. http://dx.doi.org/10.2298/tsci1403843z.
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Energy and exergy analysis of a Brayton cycle with an ideal gas is given. The irreversibility of the adiabatic processes in turbine and compressor is taken into account through their isentropic efficiencies. The net work per cycle, the thermal efficiency and the two exergy efficiencies are expressed as functions of the four dimensionless variables: the isentropic efficiencies of turbine and compressor, the pressure ratio, and the temperature ratio. It is shown that the maximal values of the net work per cycle, the thermal and the exergy efficiency are achieved when the isentropic efficiencies and temperature ratio are as high as possible, while the different values of pressure ratio that maximize the net work per cycle, the thermal and the exergy efficiencies exist. These pressure ratios increase with the increase of the temperature ratio and the isentropic efficiency of compressor and turbine. The increase of the turbine isentropic efficiency has a greater impact on the increase of the net work per cycle and the thermal efficiency of a Brayton cycle than the same increase of compressor isentropic efficiency. Finally, two goal functions are proposed for thermodynamic optimization of a Brayton cycle for given values of the temperature ratio and the compressor and turbine isentropic efficiencies. The first maximizes the sum of the net work per cycle and thermal efficiency while the second the net work per cycle and exergy efficiency. In both cases the optimal pressure ratio is closer to the pressure ratio that maximizes the net work per cycle.
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Srisiriwat, Nawadee. "Energy Analysis of Hydrogen Production from Methanol under Atmospheric Pressure and Supercritical Water Conditions." Advanced Materials Research 1119 (July 2015): 548–53. http://dx.doi.org/10.4028/www.scientific.net/amr.1119.548.
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The energy analysis of hydrogen production from the methanol reforming and oxidation under atmospheric (ATM) pressure and supercritical water (SCW) conditions was performed. The equilibrium hydrogen was investigated by the minimization of the Gibbs free energy based on Peng-Robinson equation of state for high pressure and ideal gas equation for atmospheric pressure. An objective of this study was to obtain the optimum operating conditions to maximize the net hydrogen yield, defined as the hydrogen yield taking into account also the methanol consumed by combustion to generate heat. This was done by investigating the effect of operating parameters over the following ranges: temperatures between 773 and 1273 K, pressures between 0.1 and 25.0 MPa, water-to-methanol (H2O:MeOH) ratios between 1 and 5, and oxygen-to-methanol (O2:MeOH) ratios between 0 and 1.05. At ATM pressure, it was found that the equilibrium hydrogen yield increases with increasing H2O:MeOH ratio but the peak of equilibrium H2yield is at 973 K for higher H2O:MeOH ratio than 1:1. Additionally, the total heat load increases significantly as the reaction temperature and the water amount increase. Therefore, the optimum net H2yield is at the H2O:MeOH ratio of 2:1 and the reaction temperature at 973 K. Under SCW conditions, an increase of temperature and water amount in the system constantly increases the equilibrium H2yield. It means that the high H2O:MeOH ratio and temperature are required in SCW. The presence of oxygen in hydrogen production was investigated that an increase of O2:MeOH ratio constantly decreases the H2yield and also the net H2yield for reaction at ATM pressure whereas under SCW conditions, the equilibrium H2yield and the net H2yield increase with increasing oxygen up to 0.42 and 0.84, respectively.
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Liu, Zhengnan, Rui Zhang, Zhaojing Liu, and Yuming Zhang. "Experimental Study on Swelling Behavior and Its Anisotropic Evaluation of Unsaturated Expansive Soil." Advances in Materials Science and Engineering 2021 (May 25, 2021): 1–13. http://dx.doi.org/10.1155/2021/6937240.
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Evaluation of swelling behavior is important for designing structures in expansive soils areas, especially for highway that the swelling pressure generated upon pavement and retaining structures in both vertical and horizontal directions due to infiltration. In this study, modification was made on unsaturated consolidation oedometer to provide synchronized measurement of vertical swelling strain (VSS) and lateral pressure (LP) of expansive soil under constant net normal stress and controlled matric suction. Vertical swelling (VS) test and lateral swelling (LS) test were conducted to investigate the anisotropic swelling behavior. The influence of mean net stress and net stress ratio on VSS was investigated, and the anisotropic swelling behavior of unsaturated expansive soil was characterized using anisotropic swelling ratio. The results show that the VSS nonlinearly decreased as the mean net stress increased and increased as the net stress ratio increased. The expansive soil would rapidly enter the passive state due to lateral swelling pressure under relatively low surcharge, with major principal axis rotating from vertical direction to lateral direction, which advances the possibility of passive failure for light retaining structures. The anisotropic swelling behavior objectively exists and varies with matric suction and net normal stress, which should not be ignored for engineering application.
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Cheon, Dong-Jin, Yong-Chul Kim, Jong-Ho Lee, and Sung-Won Yoon. "Experimental Investigation of Wind Pressure Characteristics for Cladding of Dome Roofs." Materials 14, no. 18 (September 13, 2021): 5266. http://dx.doi.org/10.3390/ma14185266.
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Cladding for dome roofs is often made of membrane materials that are light and easy to install. Due to these characteristics, wind damage to dome roof cladding is very common. In particular, open or retractable dome roofs are prone to wind damage because of inadequacies in wind load calculations. In this study, the wind pressure characteristics of a dome with a central opening were investigated. Wind tunnel tests were performed, and the pressure distribution was investigated by analyzing external and internal pressure coefficients. Based on the experimental results, the peak net pressure coefficients for the cladding design of a dome roof with a central opening were proposed. For the external peak pressure coefficients, the values of leeward regions were similar despite height–span ratios and turbulence intensity values. For the internal peak pressure coefficients, negative pressure was dominant, and the coefficients were not significantly affected by changes in height–span ratio. This tendency locally increased the negative peak net pressure, in which the load acts in the upward direction, and relatively significantly increased the positive peak net pressure, in which the load acts in the downward direction.
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Demers, Denis, and Serge Leroueil. "Evaluation of preconsolidation pressure and the overconsolidation ratio from piezocone tests of clay deposits in Quebec." Canadian Geotechnical Journal 39, no. 1 (February 1, 2002): 174–92. http://dx.doi.org/10.1139/t01-071.
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The preconsolidation pressure and overconsolidation ratio profiles are the most important factors related to the mechanical behaviour of clay deposits. They are interpreted on the basis of a limited number of laboratory tests, but the near-continuous information provided by the piezocone can allow local data to be extrapolated to an entire site. Numerous methods have been proposed for relating piezocone data to preconsolidation pressure and the overconsolidation ratio, but their validity is still uncertain. In this paper, nine methods are compared on the basis of data collected on 31 sensitive clay sites in Quebec whose preconsolidation pressure profiles are well known. Each method is briefly presented and the most promising are identified. The simplest method, which directly relates preconsolidation pressure to net tip resistance, also appears to be the most effective.Key words: clay, preconsolidation pressure, overconsolidation ratio, piezocone, correlations.
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Houlden, D., M. Li, and S. Portman. "Importance of ventricle-to-brain ratio (VBR) and volume of CSF drainage in the treatment of very low pressure hydrocephalus." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 42, S1 (May 2015): S43. http://dx.doi.org/10.1017/cjn.2015.194.
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Introduction: Low pressure hydrocephalus is a known complication of prolonged hydrocephalus sometimes treatable with continued low-pressure drainage at subatmospheric pressures. Clarke et. al. and Filipidis et. al. have reported poor outcomes when treating very low pressure hydrocephalus (VLPH). We present 4 cases of very low pressure hydrocephalus (VLPH) following transnasal endoscopic resection of suprasellar lesions and hypothesize that poor prognostic cases can be identified thereby avoiding prolonged futile treatments. Methods: We performed a retrospective chart review of 4 cases of VLPH and tried to identify metrics contributing to successful treatment. We examined the Pearson correlations between Glasgow Coma Scale and ventricle-to-brain ratio (VBR); volume of CSF drained; net fluids; and serum sodium, urea, and creatinine. Results: Our investigation reveals that Glasgow Coma Score is positively correlated with increased CSF drainage and negatively correlated with increased ventricle-to-brain ratio. The most important determinant of good outcome is brain compliance as measured by the brain’s ability to maintain a good GCS score in the face of wide ranges in ventricle-to-brain ratio (VBR). Conclusion: We propose that futile prolonged subatmospheric drainage be avoided by declining treatment in patients who have ventriculitis and patients who have a narrow range of ventricle-to-brain ratio (VBR) concurrent with a good neurological examination.
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Weng, Ding Wei, Qun Lei, Zi Yi Guo, and Yong Luo. "A New Method of Fracture Designing to Elevate SRV in Natural Fractured Sandstone Reservoir." Applied Mechanics and Materials 275-277 (January 2013): 1471–75. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.1471.
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This paper firstly analyze the relationship between the fracture net pressure and the sand to fluid ratio (SOR), and the conclusion is that the high SOR could accumulate high net pressure to make the natural fractures open in natural fractured sandstone reservoir. Then relationship between the cumulative oil production and opening the natural fractures is analyzed by means of reservoir numerical simulation, and the conclusion is that the cumulative oil production increased apparently as the area of opening natural fractures increasing. Based on the analyses, a new method of optimizing fracture conductivity to elevate the stimulating reservoir volume (SRV) was formed: firstly, evaluate the stress field and calculate the critical net pressure of the natural fractures opening; secondly, determine the average proppant concentration according the relationship between the net pressure and proppant concentration; thirdly, calculate the fracture conductivity according to the proppant concentration; at last, optimize the fracture length. There are two key works: one is acquiring the accurate principal stress combining the indoor experiment and field test; the other one is acquiring accurate conductivity of proppant, and long term conductivity experiments are recommended.
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Gao, You, De’an Sun, and Annan Zhou. "Hydromechanical behaviour of unsaturated soil with different specimen preparations." Canadian Geotechnical Journal 53, no. 6 (June 2016): 909–17. http://dx.doi.org/10.1139/cgj-2015-0381.
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The effect of different specimen preparation methods (compaction, reconstitution) on the hydromechanical behaviour and microstructure of soil was studied through a series of soil-water retention tests, triaxial tests, and mercury intrusion porosimetry (MIP) tests on an unsaturated clayey silt. Key findings from this experimental study include the following. (i) The air-entry value of the reconstituted specimen is higher than that of the compacted specimen with the same initial void ratio. (ii) The reconstituted specimen exhibits a unimodal pore-size distribution and the compacted specimen exhibits a bimodal pore-size distribution, according to results of the MIP tests. (iii) The soil-water characteristic curves and residual gravimetric water content of compacted and reconstituted specimens are almost the same in the high suction range. (iv) The void ratio of a reconstituted specimen decreases sharply with increasing suction value under an isotropic net stress (such as 20 kPa), while the void ratio of a compacted specimen shows a small change for the same suction change process. (v) Under the same net confining pressure, the shear strength of both compacted and reconstituted specimens increases with the suction increase. The shear strength of the reconstituted specimen is higher than that of the compacted specimen with the same density under the same suction and net confining pressure.
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Lin, Xinxing, Chonghui Chen, Aofang Yu, Likun Yin, and Wen Su. "Performance Comparison of Advanced Transcritical Power Cycles with High-Temperature Working Fluids for the Engine Waste Heat Recovery." Energies 14, no. 18 (September 17, 2021): 5886. http://dx.doi.org/10.3390/en14185886.
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To efficiently recover the waste heat of mobile engine, two advanced transcritical power cycles, namely split cycle and dual pressure cycle, are employed, based on the recuperative cycle. Performances of the two cycles are analyzed and compared through the development of thermodynamic models. Under given gas conditions, seven high-temperature working fluids, namely propane, butane, isobutane, pentane, isopentane, neopentane, and cyclopentane, are selected for the two cycles. At the design system parameters, the highest work 48.71 kW, is obtained by the split cycle with butane. For most of fluids, the split cycle has a higher work than the dual pressure cycle. Furthermore, with the increase of turbine inlet pressure, net work of the split cycle goes up firstly and then decreases, while the work of dual pressure cycle increases slowly. For the split cycle, there exists a split ratio to get the maximum network. However, for the dual pressure cycle, the larger the evaporation temperature, the higher the net work. On this basis, system parameters are optimized by genetic algorithm to maximize net work. The results indicate that the highest work 49.96 kW of split cycle is obtained by pentane. For the considered fluids, except cyclopentane, split cycle always has a higher work than dual pressure cycle. Due to the higher net work and fewer system components, split cycle is recommended for the engine waste heat recovery.
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Zhang, W., L. Chen, and F. Sun. "Performance optimization for an open-cycle gas turbine power plant with a refrigeration cycle for compressor inlet air cooling. Part 2: Power and efficiency optimization." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 223, no. 5 (May 14, 2009): 515–22. http://dx.doi.org/10.1243/09576509jpe727.
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The power and efficiency of the open cycle gas turbine power plant with a refrigeration cycle for compressor inlet air cooling with pressure drop irreversibilities are optimized based on the model established using finite time thermodynamics in Part 1 of this article by adjusting the mass flowrate (or the distribution of pressure losses along the flow path). It is shown that there are optimal air mass flowrates (or the distribution of pressure losses along the flow path) that maximize the net power output, and the maximum has additional maximum with respect to the compressor overall pressure ratio. When optimization is performed with the constraints of the fixed fuel flow and the plant size, the net power output and the thermal conversion efficiency of the cycle can be maximized again by properly allocating the fixed flow area among the compressor inlet and the power turbine outlet. The numerical examples show the effects of design parameters on the power output and heat conversion efficiency. The net power output and the thermal conversion efficiency are improved by using the refrigeration cycle for compressor air inlet cooling.
Dissertations / Theses on the topic "Net pressure ratio"
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Coltrin, Ian S. "The Influence of Nozzle Spacing and Diameter on the Acoustic Emissions of Closely Spaced Supersonic Jet Arrays." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/2935.
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The acoustic emissions from supersonic jets represent an area of significant research needs; not only in the field of aero-acoustics, but in industry as well where high pressure let down processes have been known to cause acoustically induced vibrations. A common method to reduce the acoustic emissions of such processes involves dividing the single larger supersonic flow into several smaller ones. Though this is common practice, there is not yet a current model which describes the reduction of acoustic emissions from an array of smaller supersonic jets. Current research which studies supersonic jet arrays are mainly focused on the effects of screech. Though screech is important, due to its high amplitude acoustic pressure, this research focuses on the overall acoustic emissions radiated from supersonic jet arrays which can cause severe acoustic loadings. This research investigated the acoustic emissions and shock formations from several eight by eight arrays of axisymmetric jet experimentally. The array nozzle diameters investigated ranged from 1/8 inch to 1/4 inch and the spacing over diameter ratio ranged from 1.44 to 3. The net pressure ratios investigated ranged from 2 to 24. Results revealed a strong correlation between the acoustic emissions and the shock formations of the flow. Up until a critical net pressure ratio, the overall sound pressure levels were comparable to that of a single jet within an array. At net pressure ratios beyond the critical the overall sound pressure levels transitioned to higher decibel levels; equivalent to a single jet with an equivalent exit area of an entire array. Also, the characteristic acoustic frequency emitted from a nozzle array remained ultrasonic (above 20 kHz) at lower net pressure ratios and then shifted to audible levels (between 20 Hz to 20 kHz) at net pressure ratios beyond the critical. Also, before the critical net pressure ratio the shock cells from the jets within the array remained unmerged, but at net pressure ratios beyond the critical the shock cells merged and formed lattices of weak oblique shocks at first and then strong oblique shocks as the net pressure ratio continued to increase. The critical net pressure ratio was investigated by non-dimensional analysis. The non-dimensional analysis revealed that the critical net pressure ratio was a strong linear function of the spacing over diameter ratio. A linear model was derived which is able to predict the critical net pressure ratio, and in turn, predict a critical shift in the acoustic emissions of a nozzle array.
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Procházka, Ondřej. "Metody detekce selekce v DNA sekvencích." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242086.
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The topic of semestral thesis is methods to detect selection in DNA sequences. In the begining of the thesis we will describe molecular evolution. It will be written what made the evolution and how the evolution is shown. Moreover there are gen mutations and mechanisms of diffuse and fixation. It will be defined what pozitive, negative and neutral selection is. The thesis is focused on evolution distance of synonymous and nonsynonymous substitution. There will be described three methods – Nei-Gojobori, Li-Wu-Luo and Comeron. All these methods will be described with mathematic formulas. There will be statistic test to decide what kind of selection ti is – there will be used z-test. In the practical part, there will be information about developed software what counts selection pressure from sequences from databazes in format GenBank and it shows parts where selection is. The software will be used for two data sets with two different genetic codes. The result will be discussed. We will discuss results of all three methods of selection pressure and influence of input parametrs.
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Tai, Huang Hu, and 黃虎台. "A Study of the Connections between Working Pressure and Job Satisfaction in Government Owned Radio Stations－Case Study in PRS, VOH, NER." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/56u9pe.
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碩士銘傳大學
傳播管理研究所碩士在職專班
92
After the deregulation of the broadcasting policy, government owned radio stations were facing the competition from private commercial stations. In the meantime, the government’s reengineering also affected the working attitudes of staffs who work in the public radio stations. The purpose of the study is to analyze the connections between working pressure and job satisfaction of public radio station staffs. 420 people in Police Radio Station, Voice of Han Broadcasting Network and National Education Radio Station were surveyed. The questionnaire focused on the questions of working pressure, job satisfaction and personal profiles. 370 questionnaires were collected and 365 of them were valid. SPSS was adopted into the analyzing process. The key findings are: The reasons that caused working pressures (ranked by importance): Overloaded work, The nature of the Organization, Personal Role in the organization, Lack of proper use of personal skills. The reasons that affected job satisfaction (ranked by importance): Relationship with associates, Job description, Compensation, Management leadership. The study also found that the “workload” and “the nature of the organization” didn’t affect too much on the job satisfaction. But “the job description” and “the use of personal skills” affected interviewers’ attitudes toward to job satisfaction. The level of working pressure was different among staffs with different gender, age, education background, seniority, departments and positions. Marriage status, school majors and working locations didn’t make any differences. The level of Job satisfaction was affected by gender, education background, departments, and positions. And we didn’t see any significant differences among age, marriage status, school majors, locations and seniority. The value of the study is to identify the connections between working pressures and job satisfaction. The study is also a good reference to management teams of the government owned stations.
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Huang, Hu-Tai, and 黃虎台. "A Study of the Connections between Working Pressure and Job Satisfaction in Government Owned Radio Stations.- Case Study in PRS, VOH, NER –." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/kehw59.
Full textAbstract:
碩士銘傳大學
傳播管理研究所碩士在職專班
92
After the deregulation of the broadcasting policy, government owned radio stations were facing the competition from private commercial stations. In the meantime, the government’s reengineering also affected the working attitudes of staffs who work in the public radio stations. The purpose of the study is to analyze the connections between working pressure and job satisfaction of public radio station staffs. 420 people in Police Radio Station, Voice of Han Broadcasting Network and National Education Radio Station were surveyed. The questionnaire focused on the questions of working pressure, job satisfaction and personal profiles. 370 questionnaires were collected and 365 of them were valid. SPSS was adopted into the analyzing process. The key findings are: The reasons that caused working pressures (ranked by importance): Overloaded work, The nature of the Organization, Personal Role in the organization, Lack of proper use of personal skills. The reasons that affected job satisfaction (ranked by importance): Relationship with associates, Job description, Compensation, Management leadership. The study also found that the “workload” and “the nature of the organization” didn’t affect too much on the job satisfaction. But “the job description” and “the use of personal skills” affected interviewers’ attitudes toward to job satisfaction. The level of working pressure was different among staffs with different gender, age, education background, seniority, departments and positions. Marriage status, school majors and working locations didn’t make any differences. The level of Job satisfaction was affected by gender, education background, departments, and positions. And we didn’t see any significant differences among age, marriage status, school majors, locations and seniority. The value of the study is to identify the connections between working pressures and job satisfaction. The study is also a good reference to management teams of the government owned stations.
Books on the topic "Net pressure ratio"
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Martin-Loeches, Ignacio, and Antonio Artigas. Respiratory support with positive end-expiratory pressure. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0094.
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Positive-end-expiratory pressure (PEEP) is the pressure present in the airway (alveolar pressure) above atmospheric pressure that exists at the end of expiration. The term PEEP is defined in two particular settings. Extrinsic PEEP (applied by ventilator) and intrinsic PEEP (PEEP caused by non-complete exhalation causing progressive air trapping). Applied (extrinsic) PEEP—is usually one of the first ventilator settings chosen when mechanical ventilation (MV) is initiated. Applying PEEP increases alveolar pressure and volume. The increased lung volume increases the surface area by reopening and stabilizing collapsed or unstable alveoli. PEEP therapy can be effective when used in patients with a diffuse lung disease with a decrease in functional residual capacity. Lung protection ventilation is an established strategy of management to reduce and avoid ventilator-induced lung injury and mortality. Levels of PEEP have been traditionally used from 5 to 12 cmH2O; however, higher levels of PEEP have also been proposed and updated in order to keep alveoli open, without the cyclical opening and closing of lung units (atelectrauma). The ideal level of PEEP is that which prevents derecruitment of the majority of alveoli, while causing minimal overdistension; however, it should be individualized and higher PEEP might be used in the more severe end of the spectrum of patients with improved survival. A survival benefit for higher levels of PEEP has not been yet reported for any patient under MV, but a higher PaO2/FiO2 ratio seems to be better in the higher PEEP group.
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VanCour, Shawn. Making Radio. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190497118.001.0001.
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The opening decades of the twentieth century witnessed a profound transformation in the history of modern sound media, with workers in US film, radio, and record industries developing pioneering production methods and performance styles tailored to emerging technologies of electric sound reproduction that directly shaped dominant forms and experiences of modern sound culture. Focusing on broadcasting’s initial expansion period during the 1920s, Making Radio explores the forms of creative labor pursued for the medium before the better-known network era of the 1930s and 1940s, assessing their role in shaping radio’s own identity and identifying affinities with parallel practices pursued for conversion-era film and phonography. Tracing programming forms adopted by early radio writers and programmers, production techniques developed by studio engineers, and performance styles cultivated by on-air talent, it shows how radio workers negotiated a series of broader industrial and cultural pressures to establish best practices for their medium. In the process, it argues, these sound workers shaped not only the future of broadcasting, but also contributed to much broader shifts in popular forms of music, drama, and public oratory, ushering in a new era of electric sound entertainment.
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VanCour, Shawn. Making Radio Genres. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190497118.003.0003.
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This chapter addresses processes of genre formation, exploring the role that concepts of radiogénie played in developing new programming forms and a larger sound-mindedness in period producers and audiences. Beginning with a survey of early radio genres and debates surrounding their sonic appropriateness, the chapter then pursues a more detailed case study of the period’s dominant genre, musical variety. Responding to pressures for programming with unity and distinction while ensuring varied content with broad appeal, producers pursued three key strategies for this genre: (1) inclusion of a program host as central unifying figure, (2) interstitial continuity uniting musical selections around a common theme, and (3) the “continuity program,” with weak dramatic frame stories linking otherwise diverse musical offerings. Fulfilling larger economic imperatives without compromising aesthetic potential, this third format was championed as proof of radio’s capacity to offer unique and valued contributions to an expanding field of modern sound art.
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Matzko, Paul. The Radio Right. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190073220.001.0001.
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By the early 1960s, and for the first time in history, most Americans across the nation could tune their radio to a station that aired conservative programming from dawn to dusk. People listened to these shows in remarkable numbers; for example, the broadcaster with the largest listening audience, Carl McIntire, had a weekly audience of twenty million, or one in nine American households. For the sake of comparison, that is a higher percentage of the country than would listen to conservative talk radio host Rush Limbaugh forty years later. As this Radio Right phenomenon grew, President John F. Kennedy responded with the most successful government censorship campaign of the last half century. Taking the advice of union leader Walter Reuther, the Kennedy administration used the Internal Revenue Service and the Federal Communications Commission to pressure stations into dropping conservative programs. This book reveals the growing power of the Radio Right through the eyes of its opponents using confidential reports, internal correspondence, and Oval Office tape recordings. With the help of other liberal organizations, including the Democratic National Committee and the National Council of Churches, the censorship campaign muted the Radio Right. But by the late 1970s, technological innovations and regulatory changes fueled a resurgence in conservative broadcasting. A new generation of conservative broadcasters, from Pat Robertson to Ronald Reagan, harnessed the power of conservative mass media and transformed the political landscape of America.
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VanCour, Shawn. Conclusion. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190497118.003.0007.
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Reflecting on the forms of mediamaking discussed in preceding chapters, the conclusion assesses their continued relevance for contemporary sound culture and lays out guiding principles for future scholarship. Mediamaking, it argues, entails not only the development of dominant production practices but also the professionalization and legitimation of media labor, playing a vital role in shaping new technologies. Although shifts in radio technologies, industries, content, and audiences have yielded corresponding changes in mediamaking practices throughout the past century, foundational strategies developed by radio workers during the prenetwork era have shown surprising longevity and continue to inform key dimensions of contemporary soundwork. In tracing these transformations in future histories, scholars will need to show continued consideration of more institutionally specific pressures and demands but will reap continued rewards from cultivating transmedia perspectives that connect these developments to larger shifts in period sound cultures.
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Chousterman, Benjamin, and Didier Payen. Pulmonary vasodilators in critical illness. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0039.
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Pulmonary vasodilators (PV) are commonly used in the intensive care unit (ICU) to treat pulmonary hypertension and/or hypoxaemia. The choice of drug is based on its pharmacokinetic and pharmacodynamic properties. The inhaled route of administration is preferred to treat hypoxaemia as it improves the ventilation/perfusion ratio. Systemic administration of PVs can lead to a decrease of mean arterial pressure and a worsening of hypoxaemia. Despite their beneficial effects, PVs have not shown improvement in mortality in acute respiratory distress syndrome patients. Rebound of hypoxaemia and/or pulmonary arterial hypertension should be prevented during PV treatment discontinuation with a slow de-escalation protocol. This chapter reviews the use of the main PV available for use in the ICU.
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Galderisi, Maurizio, and Sergio Mondillo. Assessment of diastolic function. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199599639.003.0009.
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Modern assessment of left ventricular (LV) diastolic function should be based on the estimation of degree of LV filling pressure (LVFP), which is the true determinant of symptoms/signs and prognosis in heart failure.In order to achieve this goal, standard Doppler assessment of mitral inflow pattern (E/A ratio, deceleration time, isovolumic relaxation time) should be combined with additional manoeuvres and/or ultrasound tools such as: ◆ Valsalva manoeuvre applied to mitral inflow pattern. ◆ Pulmonary venous flow pattern. ◆ Velocity flow propagation by colour M-mode. ◆ Pulsed wave tissue Doppler of mitral annuls (average of septal and lateral E′ velocity).In intermediate doubtful situations, the two-dimensional determination of left atrial (LA) volume can be diagnostic, since LA enlargement is associated with a chronic increase of LVFP in the absence of mitral valve disease and atrial fibrillation.Some new echocardiographic technologies, such as the speckle tracking-derived LV longitudinal strain and LV torsion, LA strain, and even the three-dimensional determination of LA volumes can be potentially useful to add further information. In particular, the reduction of LV longitudinal strain in patients with LV diastolic dysfunction and normal ejection fraction demonstrates that a subclinical impairment of LV systolic function already exists under these circumstances.
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Rasula, Jed. Acrobatic Modernism from the Avant-Garde to Prehistory. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198833949.001.0001.
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This is a book about artistic modernism contending with the historical transfigurations of modernity. As a conscientious engagement with modernity’s restructuring of the lifeworld, the modernist avant-garde raised the stakes of this engagement to programmatic explicitness. But even beyond the vanguard, the global phenomenon of jazz combined somatic assault with sensory tutelage. Jazz, like the new technologies of modernity, recalibrated sensory ratios. The criterion of the new as self-making also extended to names: pseudonyms and heteronyms. The protocols of modernism solicited a pragmatic arousal of bodily sensation as artistic resource, validating an acrobatic sensibility ranging from slapstick and laughter to the pathos of bereavement. Expressivity trumped representation. The artwork was a diagram of perception, not a mimetic rendering. For artists, the historical pressures of altered perception provoked new models, and Ezra Pound’s slogan “Make It New” became the generic rallying cry of renovation. The paradigmatic stance of the avant-garde was established by Futurism, but the discovery of prehistoric art added another provocation to artists. Paleolithic caves validated the spirit of all-over composition, unframed and dynamic. Geometric abstraction, Constructivism and Purism, and Surrealism were all in quest of a new mythology. “Making it new” yielded a new pathos in the sensation of radical discrepancy between futurist striving and remotest antiquity. The Paleolithic cave and the USSR emitted comparable siren calls on behalf of the remote past and the desired future. As such, the present was suffused with the pathos of being neither, but subject to both.
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Hajhosseiny, Reza, Kaivan Khavandi, and David J. Goldsmith. Sudden cardiac death in chronic kidney disease. Edited by David J. Goldsmith. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199592548.003.0108.
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Epidemiological data demonstrate the unique vulnerability of chronic kidney disease (CKD) subjects to cardiovascular disease, the most catastrophic being sudden cardiac death (SCD). In patients with declining kidney function there is a continuum of cardiovascular risk. In those individuals who survive to reach end-stage renal disease (ESRD), the risk of suffering a cardiac event is extremely high. Some of this risk is explained by the common risk factors and traditional cardiovascular events, namely atherosclerotic plaque fissure and rupture, but there is now evidence of a distinct ‘later CKD’ mechanism, notably arrhythmias. This appears particularly true in later stages of CKD and corresponds with the multifaceted range of myocardial and vascular insults operating. The physiological milieu of disordered vessel autoregulation, sequestered vasoprotective agents, loss of conduit and small artery elasticity/compliance, a stiffened and fibrotic myocardium, with calcified and diseased coronary arteries, all within an inflammatory environment, all contribute to arrhythmia generation. The final insult is changes in volume and electrolyte status. Risk stratification tools would be helpful in guiding clinicians to recognize those subjects likely to benefit from specific interventional strategies. These might include the novel, or emerging serum, haemodynamic, or electrocardiographic biomarkers in CKD. Current tools—such as those used for stratifying risk for SCD and determining the need for ICD implantation—are not valid in ESRD patients. Beta blockers appear likely to be generally advisable, blood pressure permitting, for patients with significant cardiomyopathy. Evidence for implantable cardiac defibrillators (ICD) is lacking. There is good reason to think that young dialysis patients at high risk of sudden death may benefit, but the risk/benefit ratio for older patients is less likely to be advantageous. These hypotheses need further investigation.
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Ferro, Charles J., and Khai Ping Ng. Recommendations for management of high renal risk chronic kidney disease. Edited by David J. Goldsmith. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199592548.003.0099.
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Poorer renal function is associated with increasing morbidity and mortality. In the wider population this is mainly as a consequence of cardiovascular disease. Renal patients are more likely to progress to end-stage renal disease, but also have high cardiovascular risk. Aiming to reduce both progression of renal impairment and cardiovascular disease are not contradictory. Focusing on the management of high-risk patients with proteinuria and reduced glomerular filtration rates, it is recommended that blood pressure should be kept below 140/90, or 130/80 if proteinuria is > 1 g/24 h (protein:creatinine ratio (PCR) >100 mg/mmol or 0.9 g/g). These targets may be modified according to age and other factors. Angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor antagonists should form part of the therapy for patients with proteinuria > 0.5 g/24 h (PCR > 50 mg/mmol or 0.45 g/g). Use of ACEIs or angiotensin receptor blockers in patients with lower levels of proteinuria may be indicated in some patient groups even in the absence of hypertension, notably in diabetic nephropathy. Evidence that other agents that reduce proteinuria bring additional benefits is weak at present. The best studies of ‘dual-blockade’ with various combinations of ACEIs, ARBs, and renin inhibitors have shown additional hazard with little evidence of additional benefit. Hyperlipidaemia—regardless of lipid levels, statin therapy is indicated in secondary cardiovascular prevention, and in primary prevention where cardiovascular risk is high, noting that current risk estimation tools do not adequately account for the increased risk of patients with CKD. There is not substantial evidence that lipid lowering therapy impacts on average rates of loss of GFR in progressive CKD. Non-drug lifestyle interventions to reduce cardiovascular risk, including stopping smoking, are important for all. Acidosis—in more advanced CKD it is justified to treat acidosis with oral sodium bicarbonate. Diet—sodium restriction to < 100 mmol/day (6 g/day) and avoidance of excessive dietary protein are justified in early to moderate CKD. Recommendations to limit levels of protein to 0.8 g/kg body weight are suggested by some, but additional protective effects of this are likely to be slight in patients who are otherwise well managed. Low-protein diets may carry some risk. Lower-protein diets may however be used to prevent symptoms in advanced CKD not treated by dialysis.
Book chapters on the topic "Net pressure ratio"
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Bolgar, Istvan, Sven Scharnowski, and Christian J. Kähler. "Effects of a Launcher’s External Flow on a Dual-Bell Nozzle Flow." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 115–27. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_7.
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Abstract Previous research on Dual-Bell nozzle flow always neglected the influence of the outer flow on the nozzle flow and its transition from sea level to altitude mode. Therefore, experimental measurements on a Dual-Bell nozzle with trans- and supersonic external flows about a launcher-like forebody were carried out in the Trisonic Wind Tunnel Munich with particle image velocimetry, static pressure measurements and the schlieren technique. A strongly correlated interaction exists between a transonic external flow with the nozzle flow in its sea level mode. At supersonic external flow conditions, a Prandtl–Meyer expansion about the nozzle’s lip decreases the pressure in the vicinity of the nozzle exit by about 55%. Therefore a new definition for the important design criterion of the nozzle pressure ratio was suggested, which considers this drastic pressure drop. Experiments during transitioning of the nozzle from sea level to altitude mode show that an interaction about the nozzle’s lip causes an inherently unstable nozzle state at supersonic free-stream conditions. This instability causes the nozzle to transition and retransition, or flip-flop, between its two modes. This instability can be eliminated by designing a Dual-Bell nozzle to transition during sub-/transonic external flow conditions.
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Gomes, Susane R., and Leopoldo J. Rocco. "Design and Testing of a Lab-Scale Hybrid Rocket Motor to Evaluate Swirl Injection Characteristics." In Energetic Materials Research, Applications, and New Technologies, 185–210. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2903-3.ch009.
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This research aims to provide a methodology for the project of labscale hybrid motors. This development began with the thermal analysis of the fuel grain using the Flynn, Wall and Ozawa method, generating simulation entry data to maximize the motor performance. The simulation was performed with the Chemical Equilibrium Specific Impulse Code. Based on the optimum oxidizer to fuel ratio, the literature was used to supply the mathematical background to calculate the motor geometrical parameters whose operating conditions were determined throughout the simulation. Finally, firing tests were conducted to verify the reliability of the project methodology. The firing tests were performed with three injectors: two swirling and one axial. The tests showed that the higher the operating pressure the more suitable is the project, meaning the methodology developed works best in hybrid rocket motors with high operating pressures. Additionally, it was shown that the swirling flow injectors produce higher efficiency.
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Mendonça, Fausto B., and Girum S. Urgessa. "Pre-Test and Analysis of a Reinforced Concrete Slab Subjected to Blast From a Non-Confined Explosive." In Energetic Materials Research, Applications, and New Technologies, 272–87. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2903-3.ch013.
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A large scale experimental program consisting of testing 10 RC slabs with different variations of concrete compressive strength, reinforcement ratio and retrofit was conducted in Brazil. As part of that test program, a small-scale blast pre-test setup and associated dynamic analysis were conducted in order to confirm the proper functioning of the blast test sensors (pressure gages, displacement meter and accelerometers). The results of the pre-test were compared with theoretical blast wave parameter predictions using established equations and maximum displacement predictions using simplified dynamic analysis. The pre-test experiment provided useful insights and was shown to be critical for the success of the subsequent large scale blast tests.
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Balasubramanian, Prabakaran. "An Attempt in Blending Higher Volume of Ethanol with Diesel for Replacing the Neat Diesel to Fuel Compression Ignition Engines." In Bioethanol [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95263.
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Alcohols are renewable in nature and can be manufactured from biomass. Butanol a higher alcohol, can be utilized as co-solvent to prevent the phase separation of diesel-ethanol blends as per the previous researches.. This experimentation has been conducted with the blends of diesel-ethanol with various proportions of n-butanol followed by the solubility test in the temperature range of 5–25°C. The results indicate that 45% of ethanol can be blended with diesel by the assistance of 10% of n-butanol to make the final blend stable up to a temperature of 5°C for 20 days, which met the requirements of the essential properties (ASTM). Existing diesel engine has been modified as per the optimal level of parameters such as intake air temperature (IAT), fuel injection timing (FIT), nozzle opening pressure (NOP) and compression ratio (CR) obtained using Taghuchi method of L9 orthogonal array. Arrived out parameters are 75°C of IAT, 29°before top dead centre of FIT, 210 bar of NOP and 19: 1 of compression ratio. The implementation of these parameters in diesel engine and fueling with diesel-ethanol butanol blend containing 45% ethanol produced closer performance and emissions characteristics compared to that of diesel. However, the emissions of smoke, hydrocarbon and carbon monoxide produced by the optimal blend are found to be marginally higher compared to that of diesel. These can be ratified by the introduction of after treatment systems modifications.
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Balasubramanian, Prabakaran. "An Attempt in Blending Higher Volume of Ethanol with Diesel for Replacing the Neat Diesel to Fuel Compression Ignition Engines." In Bioethanol Technologies. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95263.
Full textAbstract:
Alcohols are renewable in nature and can be manufactured from biomass. Butanol a higher alcohol, can be utilized as co-solvent to prevent the phase separation of diesel-ethanol blends as per the previous researches. This experimentation has been conducted with the blends of diesel-ethanol with various proportions of n-butanol followed by the solubility test in the temperature range of 5–25°C. The results indicate that 45% of ethanol can be blended with diesel by the assistance of 10% of n-butanol to make the final blend stable up to a temperature of 5°C for 20 days, which met the requirements of the essential properties (ASTM). Existing diesel engine has been modified as per the optimal level of parameters such as intake air temperature (IAT), fuel injection timing (FIT), nozzle opening pressure (NOP) and compression ratio (CR) obtained using Taghuchi method of L9 orthogonal array. Arrived out parameters are 75°C of IAT, 29° before top dead centre of FIT, 210 bar of NOP and 19: 1 of compression ratio. The implementation of these parameters in diesel engine and fueling with diesel-ethanol butanol blend containing 45% ethanol produced closer performance and emissions characteristics compared to that of diesel. However, the emissions of smoke, hydrocarbon and carbon monoxide produced by the optimal blend are found to be marginally higher compared to that of diesel. These can be ratified by the introduction of after treatment systems modifications.
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Fuller-Seeley, Kathryn H. "Becoming Benny." In Jack Benny and the Golden Age of American Radio Comedy. University of California Press, 2017. http://dx.doi.org/10.1525/california/9780520295049.003.0002.
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Jack Benny drew from a successful vaudeville career to adapt his humor to radio form in 1932. Realizing the pressures of creating new program material on a weekly basis, he hires Harry Conn. Benny and Conn develop continuing, quirky characters and “comedy situations” in imaginative spaces away from the microphone, that create a new kind of American humor. Sponsored first by Canada Dry Ginger Ale, Benny and Conn develop their program through experimentation, addition of new character Mary, and turn Jack into the “Fall Guy” who was butt of his cast members’ jokes. Friction with Harry Conn nearly derails the program, but Benny finds new writers and the program hits top radio popularity ratings by mid-decade.
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Raghavapanicker Sanal Kumar, Valsalayam, Shiv Kumar Choudhary, Pradeep Kumar Radhakrishnan, Rajaghatta Sundararam Bharath, Nichith Chandrasekaran, Vigneshwaran Sankar, Ajith Sukumaran, and Charlie Oommen. "Internal Flow Choking in Cardiovascular System: A Radical Theory in the Risk Assessment of Asymptomatic Cardiovascular Diseases." In Cardiac Diseases - Novel Aspects of Cardiac Risk, Cardiorenal Pathology and Cardiac Interventions. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96987.
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The theoretical discovery of Sanal flow choking in the cardiovascular system (CVS) demands for interdisciplinary studies and universal actions to propose modern medications and to discover new drugs to annul the risk of flow-choking leading to shock-wave generation causing asymptomatic-cardiovascular-diseases. In this chapter we show that when blood-pressure-ratio (BPR) reaches the lower-critical-hemorrhage-index (LCHI) the flow-choking could occur in the CVS with and without stent. The flow-choking is uniquely regulated by the biofluid/blood-heat-capacity-ratio (BHCR). The BHCR is well correlated with BPR, blood-viscosity and ejection-fraction. The closed-form analytical models reveal that the relatively high and the low blood-viscosity are cardiovascular-risk factors. In vitro data shows that nitrogen, oxygen, and carbon dioxide gases are predominant in fresh blood samples of the human being/Guinea-pig at a temperature range of 37–40 °C (98.6–104 °F). In silico results demonstrate the occurrence of Sanal flow choking leading to shock wave generation and pressure-overshoot in CVS without any apparent occlusion. We could conclude authoritatively, without any ex vivo or in vivo studies, that the Sanal flow choking in CVS leads to asymptomatic-cardiovascular-diseases. The cardiovascular-risk could be diminished by concurrently lessening the viscosity of biofluid/blood and flow-turbulence by increasing the thermal-tolerance level in terms of BHCR and/or by decreasing the BPR.
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Fuller-Seeley, Kathryn H. "Jack Benny’s Turn Towards Television." In Jack Benny and the Golden Age of American Radio Comedy. University of California Press, 2017. http://dx.doi.org/10.1525/california/9780520295049.003.0010.
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The new medium of television was to cause Jack Benny much consternation in how to best adapt his iconic radio program after 18 years to the new visual medium. Benny fretted and delayed his entry into New York City-based TV broadcasting until October 1950, meantime remaining radio’s top comic. But industrial pressures to switch networks (in Benny’s momentous move to CBS) and move to television, while trimming radio production budgets, and chasing audiences flocking to TV, pressed Benny to act. Benny struggled against critical expectations, and critical disdain, to find a way to merge the best of his radio narrative to TV’s visual demands. After 18 months of excoriation, critics discovered that Benny was utilizing his silent exasperated looks toward the camera and studio audience to communicate with the TV viewers. The critics pronounced Benny a marvelous TV comic. His program did change significantly in the new medium, but remained a popular favorite.
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Chong, Parkson Lee-Gau. "Membrane-Free Volume Variation with Bulky Lipid Concentration by Regular Distribution: A Functionally Important Membrane Property Explored by Pressure Studies of Phosphatidylcholine Bilayers." In High Pressure Effects in Molecular Biophysics and Enzymology. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195097221.003.0022.
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We have used the dips in the ratio of excimer to monomer fluorescence intensity (E/M) as the index of lipid regular distribution to examine the effect of pressure on lipid lateral organization in the liquid-crystalline state of dimyristoylphosphatidylcholine (DMPC)/1-palmitoyl-2-(10-pyrenyl)decanoyl)-sn-glyceroI-3-phosphatidylcholine (Pyr-PC) bilayers. In the pressure range of 0.001-0.7 kbar at 30 °C, E/M dips remain discernible, suggesting that lipid regular distribution appears favorably in the liquid-crystalline state. In the same pressure range, E/M decreases steadily with increasing pressure at noncritical mole fractions; in contrast, E/M changes little with pressure at critical mole fractions. This result reveals an important physical principle underlying lipid regular distribution—that is, that membrane free volume reaches a local minimum at critical mole fractions of bulky lipids (for example, cholesterol and Pyr-PC). Using the activity of phospholipase A2 and the membrane fluidity inferred from diphenylhexatriene fluorescence polarization, we demonstrate that regular distribution of bulky lipids has a regulatory role in membrane properties or functions. Our data show that the activity of snake venom phospholipase A2 can be significantly modulated by minute changes (for example, 0.5 mol%) in the concentration of bulky lipids on either side of a critical mole fraction as a result of membrane free volume variation. The approach employed in this study illustrates the usefulness of high-pressure fluorescence methodology for obtaining new information about membranes at ambient conditions. High-pressure fluorescence spectroscopy has emerged as a powerful tool in biophysical research during the past 15 years (Paladini & Weber, 1981; Weber, 1992). Previous fluorescence studies of membranes at high pressure were focused on dynamic aspects, particularly on membrane fluidity. These dynamic studies have included probe rotations in lipid membranes (Chong & Weber, 1983; Chong et al., 1983; Mateo et al, 1993 and references cited therein), probe lateral diffusion (Flamm et al, 1982; Muller & Galla, 1983, 1987; Turley & Offen, 1985, 1986; Eisinger & Scarlata, 1987; Macdonald et al., 1988; Kao et al., 1992), spontaneous intermembrane transfer (Mantulin et al., 1984), and the relationship of membrane dynamics to the activity of membrane-bound proteins (Chong et al, 1985; Verjovski-Almeida et al, 1986; Jona & Martonosi, 1991).
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Narayanamurthy, V. B., Richa Poddar, and R. Periyasamy. "Biomechanical Properties of the Foot Sole in Diabetic Mellitus Patients." In Biomedical Engineering, 444–60. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3158-6.ch019.
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This aricle evaluates and quantifies the biomechanical properties of the foot sole like – loss of protective sensation, hardness of the foot sole and pressure distribution parameter called Power ratio (PR) and its alterations, which have a direct effect on ulcer formation. A new parameter PRS Index is developed to understand the interplay between these parameters and its role in ulcer formation. All diabetic subjects attending the Diabetic foot clinic from Dec2003 to June 2007 undergo a standard foot examination. A total of 652 diabetic patients including 57 ulcer patients are taken for our study. The biomechanical properties include loss of protective sensation (LOPS) which is measured by 10 gm Semmes Weinstein Monofilament (SWMF). Hardness of the foot sole or absence of suppleness is tested using the Durometer (ASTM-D 2240 standards). Plantar pressure measurement is done using the PedoPowerGraph(p) which measures pressure distribution parameter PR. Foot wear properties like hardness of the insole affecting the formation of plantar ulcers was also measured. The above mentioned important parameters can be measured objectively and calculate PRS index value for diabetic with history of previous ulcer patients. We found a single entity of either the PR or shore independently cannot predict the risk for ulcer formation. In this study we found new PRS index value for diabetic with history of previous ulcer patients show significant correlation (i.e. p<0.05 level) between footwear shore and PRS index for history of previous ulcer patients. No significant correlation was shown for diabetic without history of previous ulcer patients and this may be due to diabetic patients are wearing footwear randomly with different degree Shore. From the case studies we found that the PRS index values and other biomechanical parameter of the foot sole can be reversed if the patients wear proper MCR footwear with 20 degree Shore. Use of appropriate footwear has shown that these easily measurable parameters and thus prevent ulcer formation as mentioned in the earlier studies. Several methods are used previously for predicting ulceration in DM patients. But in this study the new index PRS was studied and its role in predicting ulceration. Use of appropriate footwear will reverse the hypertrophic response; this can be quantified by the PRS index. We have found that there is decrease in PRS index by proper off loading the pressure using 20-degree shore MCR footwear.
Conference papers on the topic "Net pressure ratio"
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Li, Rongsheng, Zhiming Fang, Lihua Liang, Zengliang Gao, and Yuebao Lei. "A Global Limit Load Solution for Plates With Embedded Elliptical Cracks Under Combined Tension and Bending." In ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61878.
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A global limit load solution is obtained in this paper for an embedded elliptical crack in a plate under combined tension and bending, based on the net-section collapse principle. The limit load solution is compared with three-dimension finite (3-D) element analysis limit load solution and the global limit load solution of a plate with an embedded rectangular crack. The limit load solution developed in this paper is conservative and close to the elastic-perfectly-plastic FE solutions. It is suitable for the estimation of the limit load. By comparison, it can be observed that the limit load of an embedded elliptical crack is larger than that of a rectangular crack. The difference between limit loads of these two cracks is negligible as the ratio of the depth to length of the crack is close to zero, however, the difference gets distinct as the ratio increases. The rectangular solutions are accurate enough as the ratio is less than 0.5 in engineering applications, and the elliptical solutions are more appropriate to the calculated limit load when the ratio is larger than 0.5.
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Lei, Yuebao. "A Global Limit Load Solution for Plates With Semi-Elliptical Surface Cracks Under Combined Tension and Bending." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-2553.
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A new global limit load solution is developed in this paper for a precise semi-elliptical surface crack in a plate under combined tension and bending, based on the net-section collapse principle. The new global limit load solution is compared with finite element (FE) results for the semi-elliptical crack, and with the global limit load solution for the circumscribing rectangular crack. The predictions of the new equation are conservative and close to the elastic-perfectly-plastic FE results for shallow cracks. For narrow plates with deep cracks, however, no FE results for the global limit load are available. The differences between the limit load solutions for a semi-elliptical crack and a rectangular crack are negligible for very wide plates but significant for narrow plates, depending on the normalised crack depth and the ratio between the crack length and width of the plate.
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Iwamatsu, Fuminori, Katsumasa Miyazaki, Hidekazu Takazawa, and Koichi Saito. "Evaluation Procedure of Limit Load for Non-Aligned Multiple Flaws." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97466.
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The fitness-for-service codes such as the ASME Boiler and Pressure Vessel Code Section XI require the characterization of non-aligned multiple flaws for flaw evaluation, which is performed using a flaw alignment rule. Worldwide, almost all such codes provide their own alignment rule, often with an unclear technical basis regarding the application of the rule to plastic collapse due to ductile fracture as prescribed by limit load analysis based on a net-section approach. Therefore, evaluation procedures to calculate collapse load for non-aligned multiple flaws have been proposed in various experimental and analytical studies. In these proposals, a collapse load for non-aligned multiple flaws is evaluated using the net-section stress approach in consideration of the ratio of a distance between flaws to a flaw length parameter. However, because each study proposes its own appropriate length and distance parameters, which are based on a few experimental results limited to that study, the applicability of the proposed parameters to evaluation of collapse load for arbitrary flaw sizes and locations is unclear. In this study, we performed fracture test result on a flat plate with two through-wall flaws in order to determine appropriate parameters for the evaluation procedure of the collapse load for non-aligned multiple flaws. Appropriate parameters were determined by correlation coefficients obtained by comparison of maximum loads of fracture tests and collapse loads of evaluation with various parameters. We found that the appropriate parameters to apply the alignment rule with equations to evaluate collapse load for non-aligned flaws were the ratio of the vertical or direct distance between flaws to the maximum or average flaw length.
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Iwamatsu, Fuminori, Katsumasa Miyazaki, and Koichi Saito. "Prediction of Collapse Load Reduction due to Non-Aligned Multiple Flaws." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21806.
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Abstract Fitness-for-Service (FFS) codes, such as ASME Boiler and Pressure Vessels Code, Section XI, have flaw characterization rules for evaluation of structural integrity. Since stress corrosion cracking (SCC) and thermal fatigue frequently cause multiple flaws, FFS codes should have proximity rules as a part of flaw characterization rules. The flaw characterization rules should consider fracture modes, such as brittle fracture, ductile fracture, and plastic collapse. Those in the current codes are not divided by the fracture modes. Especially, application of the current proximity rules to plastic collapse of non-aligned multiple flaws should be validated because there are few studies for this issue. Thus, fracture tests of flat plates with through-wall flaws and finite element analysis (FEA) were conducted for predicting collapse loads due to plastic collapse. A series of the fracture tests of flat plates with non-aligned two flaws has been conducted, and a trend between the load reduction and the flaw locations was shown from the results. This trend shows that the defined net-section for non-aligned multiple flaw dominate the collapse load. For the validation the trend shown by the fracture tests, FEA was performed for predicting the measured collapse load. Equivalent plastic strain around a flaw tip dominates a collapse behavior, and an equivalent plastic strain at collapse called as fracture strain was determined for FEA. The collapse loads predicted by the fracture strain are correspond with the test results for any flaw locations. FEA conditions can interpolate and cover a wide range of flaw locations conducted by the tests. The load ratios which represent effect of flaw interaction on a collapse load were estimated by parametric FEA. The ratios were mapped to investigate the trend of the effect on a collapse load. The mapped results show that the load ratio depends on a shorter flaw length of two flaws. This trend shown by the analysis results is corresponds with the fracture test results. These results are fundamental idea to make a flaw characterization rule in the FFS codes, such as ASME BPVC Section XI, for ductile fracture evaluation.
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Wang, Pengxiang, Yijun Zhao, and Shaozeng Sun. "Process Simulation and Energy Analysis of Oxy-Coal Combustion Steam Systems (OCCSS) With Near-Zero Emissions Based on Coal Gasification." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65274.
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Oxy-coal combustion steam system with near-zero emissions (OCCSS) is a new type of power generation system, which is able to satisfy the demands for high efficiency utilization of coal and control of CO2 emissions. It is necessary to study the characteristics of the new system, since both the combustion mode and the working medium are different to the power systems utilizing conventional combustion. In the present paper, we report the process simulation of a conceptual OCCSS based on coal gasification, as well as comparisons with a conventional combustion and an oxy-fuel combustion. The model of the system was built and parametric studies showed the pressure of burners and ratios of fuel have effects on the performance of the system. The net efficiency of power generation increases quickly with the increasing pressure of the gas generator followed by a slower decrease. The net efficiency of the system increases with the increasing fuel ratio to a burner which is set before any burners with decreasing ratio. Otherwise, it decreases. The energy analysis shows the net efficiency of OCCSS is higher than the conventional combustion system and the oxy-fuel combustion system.
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Caton, Jerald A. "The Effects of Compression Ratio and Expansion Ratio on Engine Performance Including the Second Law of Thermodynamics: Results From a Cycle Simulation." In ASME 2007 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/icef2007-1647.
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This investigation quantified the effects of compression ratio and expansion ratio on performance, efficiency, and second law parameters for an automotive, spark-ignition engine. The well known increase in engine performance for increasing compression ratio and expansion ratio is demonstrated. These increases for brake engine performance are modest for compression ratios greater than about 10 for the conditions studied. The results demonstrated that the increasing friction and heat losses for the higher compression ratios are of the same order as the thermodynamic gains. Also, the results included the destruction of availability during combustion. For a part load condition, the availability destroyed decreased from about 23% for a compression ratio of 4 to about 21% for a compression ratio of 10. In addition, this study examined cases with greater expansion ratios than compression ratios. The overall cycle for these cases is often called an “Atkinson” cycle. For most cases, the thermal efficiency first increased as expansion ratio increased, attained a maximum efficiency, and then decreased. The decrease in efficiency after the maximum value was due to increased heat losses, increased friction, and ineffective exhaust processes (due to the reduced cylinder pressure at the time of exhaust valve opening). For part load cases, the higher expansion ratio provided only modest gains due to increased pumping losses associated with the constant load requirement. For the wide open throttle cases, however, the higher expansion ratios provided significant gains. For example, for a compression ratio of 10, expansion ratios of 10 and 30 provided brake thermal efficiencies of about 34% and 43%, respectively. Although the net thermodynamic gains are significant, large expansion ratios such as 30 may not be practical in most applications.
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Mohany, Atef, David Arthurs, Michael Bolduc, Marwan Hassan, and Samir Ziada. "Numerical and Experimental Investigation of Flow-Acoustic Resonance of Side-by-Side Cylinders in a Duct." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97020.
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The phenomenon of flow-excited acoustic resonance is a design concern in many engineering applications, especially when wakes of bluff bodies are encountered in ducts, piping systems, heat exchangers, and other confined systems. In this article, the case of self-excited acoustic resonance of two side-by-side cylinders in a duct with cross-flow is investigated both numerically and experimentally. A single spacing ratio between the cylinders, T/D = 2.5, is investigated, where D is the diameter of the cylinders and T is the center-to-center distance between them. The numerical investigation is performed using a finite-volume method at a Reynolds number of 30,000 to simulate the unsteady flow field, which is then coupled with a finite element simulation of the resonant sound field. The experimental investigation is performed using phase-locked Particle Image Velocimetry (PIV) during the occurrence of flow-excited acoustic resonance. The results of both methods reveal that the flow-excited acoustic resonance produces a strong oscillatory flow pattern in the cylinder wakes with strong in-phase vortex shedding being synchronized by the excited acoustic resonance. The distribution and strength of the aeroacoustic sources and sinks within the flow field have been computed by means of Howe’s theory of aerodynamic sound for both the experimental and numerical cases, with the results of the two methods comparing favorably, showing similar trends in the oscillating flow fields, and very similar trends in the distribution of net acoustic power.
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Nageswara Reddy, Pereddy. "Theoretical Assessment of Turbocharged Pulse Detonation Engine Performance at Various Flight Conditions." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14451.
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Abstract A typical Pulse Detonation Engine (PDE) cycle of operation includes three basic processes: initiation and propagation of detonation wave in the Detonation Chamber (DC); a quasi-steady exhaust of detonation products from the DC at varying pressure through the supersonic nozzle; and a steady exhaust of remained detonation products at constant pressure through the nozzle while filling the DC with fresh air. In the present work, a novel method of Turbo-charging is proposed to increase the inlet pressure/density of fresh air fed into the DC in each cycle so as to increase the thrust developed per unit area of DC. The thermodynamic cycle of operation of Turbocharged Pulse Detonation Engine (TPDE) is analyzed based on quasi-steady state one dimensional formulation, and a computer code is developed in MATLAB to simulate the cycle performance at different compressor pressure ratios. Thrust per unit area of DC, the specific thrust and the fuel-based specific impulse are estimated at various flight conditions at different pressure ratios by considering C2H4/air as the fuel-oxidizer. The net thrust developed per unit area of DC increases with an increase in compressor pressure ratio, up to the pressure ratio of 4.0, at all flight conditions. The compressor pressure ratio of about 2.0 is observed to be optimum pressure ratio as TPDE develops nearly the same air-based specific thrust at this pressure ratio irrespective of flight operating conditions.
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Hossain, Mohammad A., Lucas Agricola, Ali Ameri, James W. Gregory, and Jeffrey P. Bons. "Sweeping Jet Film Cooling on a Turbine Vane." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-77099.
Full textAbstract:
The cooling performance of sweeping jet film cooling was studied on a turbine vane suction surface in a low-speed linear cascade wind tunnel. The sweeping jet holes consist of fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of Pd/D = 6. Infrared (IR) thermography was used to estimate the adiabatic film effectiveness at several blowing ratios and two different freestream turbulence levels (Tu = 0.3% and 6.1%). Convective heat transfer coefficient was measured by a transient IR technique, and the net heat flux benefit was calculated. The total pressure loss due to sweeping jet film cooling was characterized by traversing a total pressure probe at the exit plane of the cascade. Tests were performed with a baseline shaped hole (777-shaped hole) for comparison. The sweeping jet hole showed higher adiabatic film effectiveness than the 777-shaped hole in the near hole region. Although the unsteady sweeping action of the jet augments heat transfer, the net positive cooling benefit is higher for sweeping jet holes compared to 777 hole at particular flow conditions. The total pressure loss measurement showed a 12% increase in total pressure loss at a blowing ratio of M = 1.5 for sweeping jet hole while 777-shaped hole showed a 8% total pressure loss increase at the corresponding blowing ratio.
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Tao, Joy (Xiaoya), and Lei Zhu. "Effects of Local Wall Thinning With Crack on Stress Intensity Factor for Pipes Subject to Combined Pressure and Bending." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93761.
Full textAbstract:
Abstract At ageing power plants, local thinning of pipework or vessel is unavoidable due to erosion/corrosion or other reasons such as flow accelerated corrosion (FAC) — one of the common degradation mechanisms in pipework of nuclear power plant. Local thinning reduces the structure strength, resulting in crack initiation from the corrosion pit or welding defect when subject to cyclic loading. General practice is to use the minimum thickness of the thinned area to calculate both limit load and stress intensity factor (SIF) in performing Engineering Critical Assessment (ECA) using Failure Assessment Diagram (FAD). Using the minimum thickness is normally overly conservative as it assumes that thinning occurs grossly instead of locally, leading to unnecessary early repair/replacement and cost. Performing cracked body finite element analysis (FEA) can provide accurate values of limit load and SIF, but it is time consuming and impractical for daily maintenance and emergent support. To minimise the conservatisms and provide a guidance for the assessment of locally thinned pipework or vessel using existing handbook solutions, a study was carried out by the authors on the effect of local thinning on limit loads. The study demonstrates that local thinning has significant effect on limit load if the thinning ratio of thinning depth to original thickness is larger than 25%. It concluded that the limit load solutions given in handbooks (such as R6 or the net section method) are overly conservative if using the minimum local thickness and non-conservative if using the nominal thickness. This paper discusses the effect of local thinning on SIFs of internal/external defects using cracked body finite element method (FEM). The results are compared with R6 weight function SIF solutions for a cylinder. A modified R6 SIF solution is proposed to count for the effect of local thinning profile. Along with the previous published paper on limit load it provides comprehensive understanding and guidance for fracture assessment of the local thinned pipework and vessel.