Grace Ogot

Œuvres principales

Compléments

Grace Ogot, née le et morte le , était un auteur kényan de nouvelles et de romans cool football jerseys. C’est aussi le premier auteur féminin de ce pays à avoir gagné une renommée internationale et à avoir des romans publiés par la East African Publishing House.

Née Grace Emily Akinyi le à Asembo (en), non loin de Bondo, elle est la fille de Joseph Nyanduga, un Luo convertit très tôt à l’anglicanisme.

En 1959, elle épouse l’historien et professeur Bethwell Allan Ogot, aussi un Luo, avec qui elle a quatre enfants.

Elle décède le , à l’âge de 84 ans, à l’hôpital de Nairobi (Nairobi Hospital) des suites d’une maladie.

Après des études fondamentales à la Ng’iya Girls’ School, où son père est instituteur, puis secondaires à la Butere High School, elle réussit ses études d’infirmière. Elle exerce ce métier dans les années 1950 en Ouganda et en Grande-Bretagne.

C’est alors que sa carrière suit différentes voies ; elle travaille comme sage-femme à l’hôpital de Maseno, comme professeur au collège universitaire pour la santé et les sciences de Makerere (en), comme présentatrice et journaliste entre 1959 et 1960 à la BBC avant de devenir présentatrice d’un magazine hebdomadaire radiodiffusé en langues luo et swahili à la Voice of Kenya broadcasting Company hip packs for running. Elle devient ensuite responsable du département des relations publiques à la ville de Kisumu tout en ouvrant deux boutiques de mode à Nairobi connues sous le nom de Lindy’s. Toujours insatiable d’expériences, elle occupe encore un poste de direction, toujours dans les relations publiques, à la Air India Corporation of East Africa.

En 1975 football shirts wholesale, sa carrière prend alors une tournure plus politique. Elle devient un des cinq représentants du Kenya à l’Assemblée générale des Nations unies puis membre de la délégation kényane à l’UNESCO. De 1985 à 1992, elle est l’une des première femmes parlementaires au Kenya en devenant la représentante à l’Assemblée nationale de la circonscription de Gem et la seule assistante féminine dans le Cabinet du Président Daniel Arap Moi.

Entre temps, elle est aussi un des membres fondateurs de la Writers’ Association of Kenya.

On peut estimer que Grace Ogot est l’un des plus grands auteurs de l’Afrique. Son style d’écriture est composé d’évocations vives et figurées à propos des formalités existants dans les échanges interpersonnels africains traditionnels qui sont régies par le protocole et le symbolisme.

Ses premières œuvres sont directement déterminées par la dualité entre la tradition des histoires séculaires, racontées par sa grand-mère where can i buy football shirts, et la modernité des lectures bibliques, faites par son père ainsi que largement puisées dans ses expériences acquises dans le domaine infirmier. Ainsi, son premier roman, The Promised Land, explore la question du mariage au Kenya dans les années 1930 et, plus particulièrement, le rapport d’une femme avec son mari. Elle y considère également la relation entre le passé et le présent dans la médecine traditionnelle et moderne. Plusieurs de ses histoires ont pour fond scénique le lac Victoria et les traditions des Luo. Sa prose est évocatrice du folklore traditionnel comme dans The strange bride, un roman au sujet du caractère mystique et provocateur d’une jeune-femme dans l’ancien « Luoland » (Pays luo) et écrit à l’origine en langue luo. The graduate est également un roman décrivant les complexités de l’émigration qui narre l’histoire d’un protagoniste quittant les États-Unis pour le Kenya après avoir achevé ses études.

Ses relations littéraires sur la culture des Luo pendant les périodes pré et post-coloniales sont d’une grande plus-value sociologique.

Nouvelles

Romans

En 1974, elle est interviewée par Lee Nichols pour la radio Voice of America Radio Broadcast. Une copie est disponible à la The Library of Congress (Voice of America radio series « Conversations with African writers », no 23) et est également transcrite dans le livre Conversations with African Writers (Washington, D.C. : Voice of America, 1981), p. 207-216, (OCLC ).

Shishido Station

Shishido Station (宍戸駅 Shishido-eki?) is a JR East railway station located in Kasama hydration belt australia, Ibaraki Prefecture, Japan.

Shishido Station is served by the Mito Line, and is located 48.5 km from the official starting point of the line at Oyama Station.

Shishido Station has a single curved side platform serving traffic in both direction.

Shishido Station was opened on 16 January 1889 as Ōtamachi Station (太田町駅?). It was renamed to its present name on 25 May 1889. The station was absorbed into the JR East network upon the privatization of the Japanese National Railways (JNR) on 1 April 1987. A new station building was completed in July 2012.

Coordinates:

Ласъёган

47 км

 

53,4 м

61°29′16″ с. ш. 75°15′10″ в. д.

Аган

33 км от устья

61°26′47″ с purple football socks. ш. 74°48′26″ в. д.

Россия Россия

Ханты-Мансийский автономный округ — Югра

Нижневартовский район

13.01.11.001

115204516

15 (выпуск 2)

— исток, — устье

Ласъёган — река в России, протекает в Ханты-Мансийском автономном округе, правый приток Агана. Устье реки находится на 33 км Агана. Длина реки — 47 км.

По данным государственного водного реестра России относится к Верхнеобскому бассейновому округу, водохозяйственный участок реки — Обь от впадения реки Вах до города Нефтеюганск, речной подбассейн реки — Обь ниже Ваха до впадения Иртыша. Речной бассейн реки — (Верхняя) Обь до впадения Иртыша.

Аган | Агрнъёган | Ай-Айка-Еган | Ай-Ампута | Ай-Вать-Сорт-Ягун | Ай-Вокы-Рап-Егун | Ай-Вянть-Яун | Ай-Гуёган | Ай-Гуль-Яун | Ай-Гун-Еган | Ай-Гуонт-Еган | Ай-Ими-Ягун | Ай-Ингуягун | Айкаёган | Ай-Кат-Гун-Еган | Ай-Кирилл-Высъягун | Ай-Кочет-Еган | Ай-Куй-Ёган | Ай-Кыртып-Ях | Ай-Лагрн-Еган | Ай-Люк-Ягун | Ай-Моккун-Ях | Ай-Моут-Аун | Ай-Негус-Яун | Ай-Негус-Ях | Ай-Нин-Еган | Ай-Нятлонга-Ягун | Ай-Нятым-Кор-Ягун | Ай-Ортъягун | Ай-Пор-Еган | Ай-Пыть-Ягун | Ай-Саккун-Еган | Ай-Соим | Ай-Сугмутен-Ягун | Ай-Тагр-Еган | Ай-Юх-Саем | Ай-Ягун | Ай-Яорты | Акимкина | Аккун-Ягун | Ампута | Ар-Мотоли-То-Тяха | Большой Ёган | Большая Кучиминская | Большая Рязанка | Большой Еган | Большой Куль-Еган | Большой Покур | Ванден-Игль | Вандып-Игль | Ван-Еган | Ван-Ягун | Вар-Еган | Васыг-Игль | Ватинский Ёган | Ватьёган | Вать-Сорт-Ягун | Вач-Урий-Ягун | Верхний Лобановский Еган | Верхний Пасол | Вилат | Вокы-Рап-Егун | Волокта-Ягун | Вон-Гун-Еган | Вондыр-Ягун | Вон-Ёган | Выеяй | Вылат | Горелая | Гун-Еган | Егуръеган | Егур-Ях | Егу-Урий | Еккун-Ях | Ень-Моут-Аун | Ергонгоягун | Ермаковский Еган | Ершовая Речка | Ивана Степановича | Имн-Еган | Имн-Ягун | Ингуягун | Калинина | Канж-Гун-Еган | Кань-Тять-Лама-Таха | Капей-Тяха | Кат-Гун-Еган | Кат-Той-Еган | Кат-Той-Нярсин-Ягун | Каттым-Еган | Кат-Ягун | Кау-Куй-Саем | Келем-Еган | Кильсэн-Ягун | Кирилл-Высъягун | Киселевская | Когу-Игль | Комна-Мейта | Котлунг-Ай-Ягун | Котлунг-Ай-Ягун | Котлунгъягун | Котлунгъягун | Котлунг-Яун | Кототып-Гун-Еган | Котухта | Котух-Та | Кочет-Еган | Куй-Ёган | Кулин-Еган | Кулун-Сап | Кульёган | Кумали-Ягун | Курр-Еган | Кут-Пыр-Тыл-Игль | Кутып-Еган | Кутып-Ягун | Кутып-Ягун | Кутып-Яорты | Куша-Тяха | Кыртып-Ях | Кыче-Эмтор-Еган | Лагрн-Еган | Ланкиёган | Ласх-Еган | Летняя | Лимпас | Лобановский Живец | Лонгеяун | Лопасынко | Лукен-Еган | Лупу-Ингухта | Люк-Ягун | Люлик-Еган | Люх-Ягун | Лянкой-Игль | Ляпяха-Нем-Тяха | Малая Кучиминская | Малая Селятль | Малый Вылат | Малый Ёган | Малый Покур | Малый Урьевский Еган | Масль-Вын-Тяха | Матоли-То-Тяха | Меуден-Яун | Молк-Еган | Мото-Тяха | Мохтиг | Мохтикъяун | Мохтик-Еган | Мохтикова | Мохтик-Яун | Мочкан-Еган | Мугалинка | Муглан-Еган | Муро-Ягун | Мую-Лор-Яун | Мыгыпай-Ёган | Нангъёган | Нанг-Саем-Еган | Нёхысъяун | Нёрым-Ёган | Нёрым-Ёган | Нерым-Игль | Нерым-Ягун | Нижний Лобановский Еган | Никулкина | Нин-Еган | Нишль-Манайн-Майта | Нонг-Еган | Нюча-Хапхльнутяй | Нюча-Яка | Нямты-Тяха | Нярсин-Ягун | Нятлонга-Ягун | Окунёвая | Олтын-Ягун | Омор-Ягун | Омор-Ягун | Он-Еган-Ветленя | Онтын-Ягун | Ортъягун | Оченъяун | Пай-Лор-Ягун | Пасол | Пасом | Патерен-Игль | Пеньк. Еган | Первый Саим | Пинтыръягун | Поньжа | Пор-Еган | Поталых-Еган | Почекуйка | Пр. Летний Пасол | Пуралн-Еган | Путку-Еган | Пыть-Ягун | Пыхэм-Ягун | Ранг-Ях | Репорн-Ягун | Рязанский Еган | Савуй-Пеу | Савун-Еган | Сагун-Ягун | Сагун-Ягун | Саем-Тах | Саккун-Еган | Саккун-Тох | Санкиягун | Сарт-Ёган | Селятль | Синг-Ягун | Соболиная | Соим | Сормина | Сугмутен-Ягун | Сугмутен-Ягун | Сугмутен-Ягун | Сугмутен-Яун | Сугмутенъях | Сукур-Яун | Сулькы-Ягун | Сутлымка | Сыгль-Игль | Сымту | Тагр-Еган | Талеем-Ягун | Тлесы-Ягун | Тливум-Ягун | Тлоктлы-Еган | Тлунгъягун | Тлунгъягун | Тлюгулюнг-Ягун | Тлятты-Ягун | Тоньехльтыта | Тромъёган | Турын-Яун | Тыкель-Корн-Игль | Тынась-Яун | Тюшами | Тягель | Тяэтль-Тяха | Угпан-Ягун | Ульп-Ягун | Ульт-Ильп-Ягун | Ульт-Ягун | Урий-Пит-Еган | Урьев Еган | Хапхльнутяй | Харвер-Тяха | Чень-Тяха | Эгут-Ягун | Эй-Ай-Ягун | Эй-Гун-Еган | Эй-Еган | Эй-Ягун | Элле-Вон-Еган | Энтль-Имиягун | Энтль-Ампута | Энтль-Гун-Ёган | Энтль-Гун-Ёган | Энтль-Игль | Энтль-Моккун-Ях | Энтль-Негус-Ях | Югот | Юх-Ёган | Юхкун-Ингу-Ягун | Юхкун-Ингу-Ягун | Юхкун-Ягун | Ягмун-Ягун

Axial compressor

An axial compressor is a compressor that can continuously pressurise gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from other rotating compressors such as centrifugal compressors, axi-centrifugal compressors and mixed-flow compressors where the fluid flow will include a “radial component” through the compressor. The energy level of the fluid increases as it flows through the compressor due to the action of the rotor blades which exert a torque on the fluid. The stationary blades slow the fluid, converting the circumferential component of flow into pressure. Compressors are typically driven by an electric motor or a steam or a gas turbine.

Axial flow compressors produce a continuous flow of compressed gas, and have the benefits of high efficiency and large mass flow rate, particularly in relation to their size and cross-section. They do, however, require several rows of airfoils to achieve a large pressure rise, making them complex and expensive relative to other designs (e.g. centrifugal compressors).

Axial compressors are integral to the design of large gas turbines such as jet engines, high speed ship engines, and small scale power stations. They are also used in industrial applications such as large volume air separation plants, blast furnace air, fluid catalytic cracking air, and propane dehydrogenation. Due to high performance, high reliability and flexible operation during the flight envelope, they are also used in aerospace engines.

Axial compressors consist of rotating and stationary components. A shaft drives a central drum, retained by bearings, which has a number of annular airfoil rows attached usually in pairs, one rotating and one stationary attached to a stationary tubular casing. A pair of rotating and stationary airfoils is called a stage. The rotating airfoils, also known as blades or rotors, accelerate the fluid. The stationary airfoils, also known as stators or vanes, convert the increased rotational kinetic energy into static pressure through diffusion and redirect the flow direction of the fluid, preparing it for the rotor blades of the next stage. The cross-sectional area between rotor drum and casing is reduced in the flow direction to maintain an optimum Mach number using variable geometry as the fluid is compressed.

As the fluid enters and leaves in the axial direction, the centrifugal component in the energy equation does not come into play. Here the compression is fully based on diffusing action of the passages.The diffusing action in stator converts absolute kinetic head of the fluid into rise in pressure. The relative kinetic head in the energy equation is a term that exists only because of the rotation of the rotor. The rotor reduces the relative kinetic head of the fluid and adds it to the absolute kinetic head of the fluid i.e., the impact of the rotor on the fluid particles increases its velocity (absolute) and thereby reduces the relative velocity between the fluid and the rotor. In short, the rotor increases the absolute velocity of the fluid and the stator converts this into pressure rise. Designing the rotor passage with a diffusing capability can produce a pressure rise in addition to its normal functioning. This produces greater pressure rise per stage which constitutes a stator and a rotor together. This is the reaction principle in turbomachines. If 50% of the pressure rise in a stage is obtained at the rotor section, it is said to have a 50% reaction.

The increase in pressure produced by a single stage is limited by the relative velocity between the rotor and the fluid, and the turning and diffusion capabilities of the airfoils. A typical stage in a commercial compressor will produce a pressure increase of between 15% and 60% (pressure ratios of 1.15–1.6) at design conditions with a polytropic efficiency in the region of 90–95%. To achieve different pressure ratios, axial compressors are designed with different numbers of stages and rotational speeds. As a rule of thumb we can assume that each stage in a given compressor has the same temperature rise (Delta T). Therefore, at the entry, temperature (Tstage) to each stage must increase progressively through the compressor and the ratio (Delta T)/(Tstage) entry must decrease, thus implying a progressive reduction in stage pressure ratio through the unit. Hence the rear stage develops a significantly lower pressure ratio than the first stage. Higher stage pressure ratios are also possible if the relative velocity between fluid and rotors is supersonic, but this is achieved at the expense of efficiency and operability. Such compressors, with stage pressure ratios of over 2, are only used where minimizing the compressor size, weight or complexity is critical, such as in military jets. The airfoil profiles are optimized and matched for specific velocities and turning. Although compressors can be run at other conditions with different flows, speeds, or pressure ratios, this can result in an efficiency penalty or even a partial or complete breakdown in flow (known as compressor stall and pressure surge respectively). Thus, a practical limit on the number of stages, and the overall pressure ratio, comes from the interaction of the different stages when required to work away from the design conditions. These “off-design” conditions can be mitigated to a certain extent by providing some flexibility in the compressor. This is achieved normally through the use of adjustable stators or with valves that can bleed fluid from the main flow between stages (inter-stage bleed). Modern jet engines use a series of compressors, running at different speeds; to supply air at around 40:1 pressure ratio for combustion with sufficient flexibility for all flight conditions.

The law of moment of momentum states that the sum of the moments of external forces acting on a fluid which is temporarily occupying the control volume is equal to the net change of angular momentum flux through the control volume.

The swirling fluid enters the control volume at radius,






r



1







{\displaystyle r_{1}\,}


, with tangential velocity,






V



w


1







{\displaystyle V_{w1}\,}


, and leaves at radius,






r



2







{\displaystyle r_{2}\,}


, with tangential velocity,






V



w


2







{\displaystyle V_{w2}\,}


.

Rate of change of momentum, F is given by the equation:

Power consumed by an ideal moving blade, P is given by the equation:

Change in enthalpy of fluid in moving blades:

Therefore,

which implies,

Isentropic compression in rotor blade,

Therefore,

which implies

Degree of Reaction, The pressure difference between the entry and exit of the rotor blade is called reaction pressure. The change in pressure energy is calculated through degree of reaction.

Therefore,

A nonlinear model is developed to predict the transient response of a compression system subsequent to a perturbation from steady operating conditions. It is found that for the system investigated there is an important nondimensional parameter on which this response depends. Whether this parameter is above or below a critical value determines which mode of compressor instability, rotating stall or surge, will be encountered at the stall line. Representation of the performance characteristics of axial compressor can be done by following parameters:

Axial compressors, particularly near design conditions are, on the whole, amenable to analytical treatment, and usually a good estimate of their performance can be made before they are run. Away from the design points, the performances are conveniently thought of in terms of the overall characteristics of pressure-rises, temperature-rises, and efficiencies plotted against mass-flows.

we can determine performance of axial compressor

Difference between the ideal and actual curve arises due to stage loss. Stages losses in compressor are mainly due to blade friction, flow separation, unsteady flow and vane-blade spacing.

The performance of a compressor is defined according to its design. But in actual practice, the operating point of the compressor deviates from the design- point which is known as off-design operation.





ψ



=


ϕ



(


tan







α




2








tan







α




1




)





{\displaystyle \psi =\phi (\tan \alpha _{2}-\tan \alpha _{1})\,}


 

 

 

 

(1)





tan







α




2




=




1


ϕ









tan







β




2







{\displaystyle \tan \alpha _{2}={\frac {1}{\phi }}-\tan \beta _{2}\,}


 

 

 

 

(2)

from equation (1) and (2)

The value of





(


tan







β




2




+


tan







α




1




)





{\displaystyle (\tan \beta _{2}+\tan \alpha _{1})\,}


doesn’t change for a wide range of operating points till stalling. Also






α




1




=



α




3







{\displaystyle \alpha _{1}=\alpha _{3}\,}


because of minor change in air angle at rotor and stator, where






α




3







{\displaystyle \alpha _{3}\,}


is diffuser blade angle.

Representing design values with (‘)










ψ










=


1






J


(



ϕ







)







J





=





1







ψ









ϕ















{\displaystyle {\begin{aligned}\psi ‘&=1-J(\phi ‘)\,\\J&={\frac {1-\psi ‘}{\phi ‘}}\end{aligned}}}


 

 

 

 

(3)

for off-design operations (from eq. 3):

for positive values of J, slope of the curve is negative and vice versa.

In the plot of pressure-flow rate the line separating graph between two regions- unstable and stable is known as the surge line. This line is formed by joining surge points at different rpms. Unstable flow in axial compressors due to complete breakdown of the steady through flow is termed as surging. This phenomenon affects the performance of compressor and is undesirable.

Suppose the initial operating point D (








m


˙






,



P



D







{\displaystyle {\dot {m}},P_{D}\,}


) at some rpm N. On decreasing the flow- rate at same rpm along the characteristic curve by partial closing of the valve, the pressure in the pipe increases which will be taken care by increase in input pressure at the compressor. Further increase in pressure till point P (surge point), compressor pressure will increase. Further moving towards left keeping rpm constant, pressure in pipe will increase but compressor pressure will decrease leading to back air-flow towards the compressor. Due to this back flow, pressure in pipe will decrease because this unequal pressure condition cannot stay for a long period of time. Though valve position is set for lower flow rate say point G but compressor will work according to normal stable operation point say E, so path E-F-P-G-E will be followed leading to breakdown of flow, hence pressure in the compressor falls further to point H(






P



H







{\displaystyle P_{H}\,}


). This increase and decrease of pressure in pipe will occur repeatedly in pipe and compressor following the cycle E-F-P-G-H-E also known as the surge cycle.

This phenomenon will cause vibrations in the whole machine and may lead to mechanical failure. That is why left portion of the curve from the surge point is called unstable region and may cause damage to the machine. So the recommended operation range is on the right side of the surge line.

Stalling is an important phenomenon that affects the performance of the compressor. An analysis is made of rotating stall in compressors of many stages, finding conditions under which a flow distortion can occur which is steady in a traveling reference frame, even though upstream total and downstream static pressure are constant. In the compressor, a pressure-rise hysteresis is assumed. It is a situation of separation of air flow at the aero-foil blades of the compressor. This phenomenon depending upon the blade-profile leads to reduced compression and drop in engine power.

Negative stall is negligible compared to the positive stall because flow separation is least likely to occur on the pressure side of the blade.

In a multi-stage compressor, at the high pressure stages, axial velocity is very small. Stalling value decreases with a small deviation from the design point causing stall near the hub and tip regions whose size increases with decreasing flow rates. They grow larger at very low flow rate and affect the entire blade height. Delivery pressure significantly drops with large stalling which can lead to flow reversal. The stage efficiency drops with higher losses.

Non-uniformity of air flow in the rotor blades may disturb local air flow in the compressor without upsetting it. The compressor continues to work normally but with reduced compression. Thus, rotating stall decreases the effectiveness of the compressor.

In a rotor with blades moving say towards right. Let some blades receives flow at higher incidence, this blade will stop positively. It creates obstruction in the passage between the blade to its left and itself. Thus the left blade will receive the flow at higher incidence and the blade to its right with decreased incidence. The left blade will experience more stall while the blade to its right will experience lesser stall. Towards the right stalling will decrease whereas it will increase towards its left. Movement of the rotating stall can be observed depending upon the chosen reference frame.

Early axial compressors offered poor efficiency, so poor that in the early 1920s a number of papers claimed that a practical jet engine would be impossible to construct. Things changed after A. A. Griffith published a seminal paper in 1926, noting that the reason for the poor performance was that existing compressors used flat blades and were essentially “flying stalled”. He showed that the use of airfoils instead of the flat blades would increase efficiency to the point where a practical jet engine was a real possibility. He concluded the paper with a basic diagram of such an engine, which included a second turbine that was used to power a propeller.

Although Griffith was well known due to his earlier work on metal fatigue and stress measurement, little work appears to have started as a direct result of his paper. The only obvious effort was a test-bed compressor built by Hayne Constant, Griffith’s colleague at the Royal Aircraft Establishment. Other early jet efforts, notably those of Frank Whittle and Hans von Ohain, were based on the more robust and better understood centrifugal compressor which was widely used in superchargers. Griffith had seen Whittle’s work in 1929 and dismissed it, noting a mathematical error, and going on to claim that the frontal size of the engine would make it useless on a high-speed aircraft.

Real work on axial-flow engines started in the late 1930s, in several efforts that all started at about the same time. In England, Hayne Constant reached an agreement with the steam turbine company Metropolitan-Vickers (Metrovick) in 1937, starting their turboprop effort based on the Griffith design in 1938. In 1940, after the successful run of Whittle’s centrifugal-flow design, their effort was re-designed as a pure jet, the Metrovick F.2. In Germany, von Ohain had produced several working centrifugal engines, some of which had flown including the world’s first jet aircraft (He 178), but development efforts had moved on to Junkers (Jumo 004) and BMW (BMW 003), which used axial-flow designs in the world’s first jet fighter (Messerschmitt Me 262) and jet bomber (Arado Ar 234). In the United States, both Lockheed and General Electric were awarded contracts in 1941 to develop axial-flow engines, the former a pure jet, the latter a turboprop. Northrop also started their own project to develop a turboprop, which the US Navy eventually contracted in 1943. Westinghouse also entered the race in 1942, their project proving to be the only successful one of the US efforts, later becoming the J30.

By the 1950s every major engine development had moved on to the axial-flow type. As Griffith had originally noted in 1929, the large frontal size of the centrifugal compressor caused it to have higher drag than the narrower axial-flow type. Additionally the axial-flow design could improve its compression ratio simply by adding additional stages and making the engine slightly longer. In the centrifugal-flow design the compressor itself had to be larger in diameter, which was much more difficult to “fit” properly on the aircraft. On the other hand, centrifugal-flow designs remained much less complex (the major reason they “won” in the race to flying examples) and therefore have a role in places where size and streamlining are not so important. For this reason they remain a major solution for helicopter engines, where the compressor lies flat and can be built to any needed size without upsetting the streamlining to any great degree.

In the jet engine application, the compressor faces a wide variety of operating conditions. On the ground at takeoff the inlet pressure is high, inlet speed zero, and the compressor spun at a variety of speeds as the power is applied. Once in flight the inlet pressure drops, but the inlet speed increases (due to the forward motion of the aircraft) to recover some of this pressure, and the compressor tends to run at a single speed for long periods of time.

There is simply no “perfect” compressor for this wide range of operating conditions. Fixed geometry compressors, like those used on early jet engines, are limited to a design pressure ratio of about 4 or 5:1. As with any heat engine, fuel efficiency is strongly related to the compression ratio, so there is very strong financial need to improve the compressor stages beyond these sorts of ratios.

Additionally the compressor may stall if the inlet conditions change abruptly, a common problem on early engines. In some cases, if the stall occurs near the front of the engine, all of the stages from that point on will stop compressing the air. In this situation the energy required to run the compressor drops suddenly, and the remaining hot air in the rear of the engine allows the turbine to speed up[citation needed] the whole engine dramatically. This condition, known as surging, was a major problem on early engines and often led to the turbine or compressor breaking and shedding blades.

For all of these reasons, axial compressors on modern jet engines are considerably more complex than those on earlier designs.

All compressors have an optimum point relating rotational speed and pressure, with higher compressions requiring higher speeds. Early engines were designed for simplicity, and used a single large compressor spinning at a single speed. Later designs added a second turbine and divided the compressor into low-pressure and high-pressure sections, the latter spinning faster. This two-spool design, pioneered on the Bristol Olympus, resulted in increased efficiency. Further increases in efficiency may be realised by adding a third spool, but in practice the added complexity increases maintenance costs to the point of negating any economic benefit. That said, there are several three-spool engines in use, perhaps the most famous being the Rolls-Royce RB211, used on a wide variety of commercial aircraft.

As an aircraft changes speed or altitude, the pressure of the air at the inlet to the compressor will vary. In order to “tune” the compressor for these changing conditions, designs starting in the 1950s would “bleed” air out of the middle of the compressor in order to avoid trying to compress too much air in the final stages. This was also used to help start the engine, allowing it to be spun up without compressing much air by bleeding off as much as possible. Bleed systems were already commonly used anyway, to provide airflow into the turbine stage where it was used to cool the turbine blades eco friendly reusable water bottles, as well as provide pressurized air for the air conditioning systems inside the aircraft.

A more advanced design, the variable stator, used blades that can be individually rotated around their axis, as opposed to the power axis of the engine. For startup they are rotated to “closed”, reducing compression, and then are rotated back into the airflow as the external conditions require. The General Electric J79 was the first major example of a variable stator design, and today it is a common feature of most military engines.

Closing the variable stators progressively, as compressor speed falls, reduces the slope of the surge (or stall) line on the operating characteristic (or map), improving the surge margin of the installed unit. By incorporating variable stators in the first five stages, General Electric Aircraft Engines has developed a ten-stage axial compressor capable of operating at a 23:1 design pressure ratio.

The relative motion of the blades to the fluid adds velocity or pressure or both to the fluid as it passes through the rotor. The fluid velocity is increased through the rotor, and the stator converts kinetic energy to pressure energy. Some diffusion also occurs in the rotor in most practical designs.

The increase in velocity of the fluid is primarily in the tangential direction (swirl) and the stator removes this angular momentum.

The pressure rise results in a stagnation temperature rise. For a given geometry the temperature rise depends on the square of the tangential Mach number of the rotor row. Current turbofan engines have fans that operate at Mach 1.7 or more, and require significant containment and noise suppression structures to reduce blade loss damage and noise.

A map shows the performance of a compressor and allows determination of optimal operating conditions. It shows the mass flow along the horizontal axis, typically as a percentage of the design mass flow rate, or in actual units. The pressure rise is indicated on the vertical axis as a ratio between inlet and exit stagnation pressures.

A surge or stall line identifies the boundary to the left of which the compressor performance rapidly degrades and identifies the maximum pressure ratio that can be achieved for a given mass flow. Contours of efficiency are drawn as well as performance lines for operation at particular rotational speeds.

Operating efficiency is highest close to the stall line. If the downstream pressure is increased beyond the maximum possible the compressor will stall and become unstable.

Typically the instability will be at the Helmholtz frequency of the system, taking the downstream plenum into account.

NGC 7668

NGC 7668 (ook: NGC 7669 en NGC 7670) is een niet-bestaand object in het sterrenbeeld Vissen. Het hemelobject werd in 1865 ontdekt door de Italiaanse astronoom Gaspare Stanislao Ferrari wave water bottles.

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Association for the ill and deprived

Welfare Association for the Ill and Deprived (Welfare AID) is a charity organization run by students at Ziauddin University in Karachi, Sindh, Pakistan]]. Their main focus is to provide help with health costs brazil t shirt soccer, targeting underprivileged patients to fund diagnostic tests best running hydration vest, consultations, medications, and surgeries. Welfare AID was the first charity organization established at Ziauddin University, by the University’s Vice Chancellor. It has also been involved in Flood Relief Campaigns of 2010 and 2011 providing medical care to over 30,000 patients in total and receiving recognition from the Chief of Air Force Staff of Pakistan. Welfare AID is a progressive, young organization which has been involved in numerous health related projects in Karachi, including but not limited to Hepatitis B Campaigns, school child check ups.

Welfare AID has taken tremendous steps in finding new ways of fundraising. Education based fundraisers such as Basic Life Support football turf socks, Surgical Skills Workshops, and Continuous Medical Education Conferences have become the trademark of this organization, increasing awareness and raising funds as well. They also have a blood bank and a drug bank which maintains a supply of blood for emergencies for any patient as well as drugs.

Sinkadus (TV-serie)

Sinkadus är en svensk TV-serie i sex delar från 1980 i regi av Leif Krantz och producerad av Drakfilm. Serien har sänts i SVT två gånger, 1980 och 1997, och släpptes på DVD i juli 2009 eco stainless steel water bottle. Det är en fristående fortsättning på serien Ärliga blå ögon från 1977. Stig Ossian Ericson spelar åter kommissarie Simonsson, liksom han gjorde i den serien.

En rånarliga bestående av Conny Klack (Leif Magnusson), Josef Brandt (Nils Eklund) och Robert Bintje (Tommy Nilson) rånar en värdetransport med guldtackor. De gömmer sedan guldet i bagaget till en stulen och falskskyltad bil som hämtas av ligans fjärde medlem, Ros-Marie Larsson (Mona Seilitz). Det slumpar sig dock så att de lämnat rånbytet i fel bil, en bil med exakt samma registreringsnummer som den falskskyltade goalkeeper outfits. Detta nummer är HAM753 workout belt to hold phone.

Bilen visar sig tillhöra den deprimerade och livströtte John Hissing (Hans Ernback). När denne upptäcker guldet i bagaget tar dock hans liv en enorm förändring till det bättre i alla avseenden. Redan när ligan snokat rätt på honom och hotar honom lyckas han inte bara övertala dem att få behålla en del av guldet utan blir även medlem i ligan. Dessutom så blir han och Ros-Marie Larsson förälskade i varandra. Ryktet om guldbytet cirkulerar dock i den undre världen och den farlige maffiabossen “Tryffelsvinet” konfronterar ligan och hotar dem om han inte får del av vinsten.

Efter att både Josef Brandt och Conny Klack mördats av Tryffelsvinet bestämmer sig de övriga i ligan för att fly åt varsitt väderstreck. John Hissing västerut, Ros-Marie Larsson norrut och Robert Bintje söderut.

Tryffelsvinet lyckas spåra John Hissing till Färöarna. Den djärve Hissing väljer då att istället konfrontera gangsterkungen och dödar honom i en uppgörelse i bergen. Med hotet från Tryffelsvinet undanröjt återförenas ligan och John Hissing meat tenderiser tool, vars rykte vuxit i den undre världen, tar ledningen och planerar ett ännu större rån.

Serien slutar med att rånet lyckas.

Dessutom medverkade:

m.fl.

Active Islamic Youth

Active Islamic Youth (Bosnian: Aktivna islamska omladina) was a small youth organization based in Bosnia and Herzegovina. It was active in the Bosnian postwar period. According to some media reports, it was described as a front for the Saudi High Commission for Relief and the Al-Haramain Islamic Foundation.

AIO was the first publisher of the Islamic magazine Saff, with an estimated circulation of 9 running bottle holder,000.

The AIO was launched after the 1992-1995 Bosnian war, when a group of young Bosnian Muslims decided to form the organization to promote the Islamic teachings they learned from the Arab volunteers who fought on the Bosnian side during the war. The volunteers were also Islamic missionaries. They distributed Islamic literature. Some of the literature tend to designate dozens of habits of the Bosnian Muslims that had nothing to do with the Wahabi teachings and that had to be corrected. These Arab fighters and missionaries influenced some of the young Bosniaks who joined the Bosnian Mujahideen during the war. After the war, these young people went on to form AIO.

AIO’s mission is to awaken the religious feelings of Bosnian Muslims – who, the organization believes, have been deprived of the real Islam for too long, first by the Communist regime of the former Yugoslavia, and later by the traditional mainstream Bosnian Muslims. The AIO emphasises that it aspires to original Islamic teachings as preached by Mohammed, and that it does not accept any “novelties” in Islam. Members of the AIO are known for their atypical way of praying, and for their Middle-East-style clothes and long beards thermos dishwasher safe. The men do not shake hands with women, and the women wear headscarves in public.

People associated with AIO are reported to have behaved violently, including during demonstrations. Leaders of AIO are said to have made inflammatory statements in which they criticized Bosnian Muslims for accepting too many habits of their Christian neighbours sports socks wholesale. On 24 December 2002 a young Muslim fanatic, Muamer Topalovic, shot three members of a Croat returnee family in Konjic, 80 km south of Sarajevo. Topalovic, who confessed to the killing, said that he wanted to do something against Croats. He was subsequently arrested and sentenced to 35 years in prison. Police said that Topalovic told them during the investigation that he was a member of AIO. That was later proven false. AIO leaders, however, acknowledged the possibility that Topalovic might have attended some of the courses the group organized.

After 11 September 2001, Bosnian police have taken a keener interest in AIO’s activities. It became clear that some of the Arab teachers who had impressed AIO’s founders were potential threat. AIO premises were raided several times, and its finances were thoroughly audited. It has been established that AIO received donations in the past from large Saudi charities, such as the Al Haramain Foundation. In the fall of 2002, U.S. authorities declared Al Haramain a sponsor of terrorist networks and froze its assets in the United States and Bosnia and Herzegovina.

Today, the number of people associated with AIO is shrinking. The organization is experiencing financial troubles, as many of its former donors have stopped sending money because of the bad reputation that AIO has acquired. It covers its expenses through internet clubs and from selling Islamic magazines and literature, but its future is uncertain.

Codex Wallerstein

Codex Wallerstein eller Vonn Baumanns Fechtbuch (Oettingen-Wallerstein Cod. I.6.4o.2 football t shirts for boys, Universität Augsburg) er en samling på tre afskrifter fra 1500-tallet af 1400-tals fechtbuch-manuskripter på sammenlagt 221 sider.

I manuskriptet står 1549. Vom baumanns 108, hvilket indikerer, at det har tilhørt en Michael Baumann, som var købmand (ifølge skatteoversigterne i Augsburg) mellem 1471 og 1495. Manuskriptet kom i Paulus Hector Mair besiddelse i 1556. Efter Mairs henrettelse i 1579 er manuskriptet muligvis gået videre til Marcus Fuggers bibliotek, som blev solgt af hans barnebarn i 1653 til Oettingen-Wallersteinsche Bibliothek.

Første del (A) viser fægteteknikker med langsværd, daggert og messer. Anden del (B) er indsat i to dele, hvoraf den første ligger i del A og omhandler brydningsteknikker. Del A og B er skrevet omkring 1470; papiret er fra 1464/5 baseret på vandmærket. Del A er nok en en af de kilder, som Albrecht Dürers fægtebog fra 1512 bygger på weston meat tenderizer.

Tredje del (C) er ældre end de to første og er fra første halvdel af 1400-tallet buy football shirts cheap. Papiret er fra 1420 baseret på vandmærket. Denne del omhandler langsværd colored water in glass bottles, kamp i rustning, stechschild og brydning.

Den sidste side, fol. 109r, indeholder et register håndskrevet af Paulus Hector Mair (foll. 109v og 100 er tomme).

Aktionsgemeinschaft Dienst für den Frieden

Die Aktionsgemeinschaft Dienst für den Frieden (AGDF) ist ein Zusammenschluss von 34 Organisationen und Institutionen, die mit unterschiedlichen Schwerpunkten und Arbeitsprogrammen im In- und Ausland Friedensarbeit leisten school team uniforms. Das Leitbild der AGDF ist der biblische Friedensbegriff, wie er im „Konziliaren Prozess für Gerechtigkeit, Frieden und Bewahrung der Schöpfung“ aufgegriffen wird. Es gibt allerdings auch einige Mitgliedsorganisationen, deren Einsatz für Frieden von der Tradition der Menschenrechte hergeleitet ist reusable stainless steel water bottles. Die AGDF sieht diese beiden Linien als sich gegenseitig korrigierend und befruchtend an. Die AGDF arbeitet eng mit der evangelischen Kirche in Deutschland (EKD) zusammen, betont dabei aber ihre strukturelle Eigenständigkeit.

Im Juni 1981 rief die AGDF gemeinsam mit der Aktion Sühnezeichen Friedensdienste am Rande des 19. Deutschen Evangelischen Kirchentages in Hamburg für den 10. Oktober 1981 zur Friedensdemonstration im Bonner Hofgarten 1981 auf.

Im September 1985 publizierte die AGDF zusammen mit der Aktion Sühnezeichen Friedensdienste auf dem 21 buy football socks online. Deutschen Evangelischen Kirchentag in Düsseldorf die fünf Düsseldorfer Friedensthesen gegen militärische Abschreckungspotentiale, für eine gerechtere Verteilung des Reichtums auf der Welt, für eine Verweigerung des Kriegsdienstes, für Gewaltfreiheit glass water serving bottle.

Die AGDF hat drei thematische Fachbereiche:

Die AGDF ist selbst wiederum Mitglied in verschiedenen nationalen wie internationalen Organisationen, unter anderem: