مقاله درباره Selection Of A Gas Turbine Cooling System

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تعداد صفحات: 358

دانشگاه آزاداسلامی واحد کرج

عنوان پایان نامه:

انتخاب یک سیستم خنک سازی توربین گازی

Boris Glezer

راه حل های توربین بهینه سازی شده, سان دیگو, کالیفرنیا, U.S.A

استاد:

آقای مهندس سرخواه

دانشجو:

محسن گودرزی

شماره دانشجویی:

80461255578

زمستان 84

تقدیم به پدر عزیزم

و تشکر از زحمات بی وقفه اش که هر چه هستم از اوست.

محسن گودرزی

دانشجوی رشته مکا نیک

دانشگاه آزادواحدکرج

22/11/84 مقدمه....................................................................................................................................................1

خنک سازی توربین بعنوان یک تکنولوژی کلیدی برای بهینه سازی موتورهای توربین گازی....................................................................................................................................................7

چالش های خنک سازی برای دماهای پیوسته درحال افزایش گاز ونسبت فشارکمپرسور........................8

تکنیک های خنک سازی استفاده شده متداول.....................................................................................14

تاثیر خنک سازی.................................................................................................................................18

مشکلات خنک سازی..........................................................................................................................22

ترکیب پوشش های حصار حرارتی و خنک سازی..................................................................................30

فرایند بهبود خنک سازی ایرفویل........................................................................................................32

تعریف پارامترهای شباهت انتقال جرم و حرارت اصلی...........................................................................35

کنش متقابل انتقال جرم – حرارت در لایه مرزی ایرفویل.......................................................................36

نقش تشابه در رقابت تجربی حرارت ایرفویل توربین و انتقال جرم.........................................................42

موضوعات انتقال حرارت گذرا و پایدار در بخش داغ موتور.....................................................................44

دمای فلز و تاثیر آن روی عمر اجزای توربین.......................................................................................46

موضوعات مربوط به تغییرمکان های دمایی گذرای روتوربه استاتوروکنترل فاصله نوک آزاد..................48

خنک سازی نازل توربین......................................................................................................................56

تقابل با محفظه احتراق........................................................................................................................58

انتقال حرارت پره..............................................................................................................................65

-خمیدگی......................................................................................................................................69

-تاثیرات ناهمواری..........................................................................................................................74

-اغتشاش.....................................................................................................................................................76

خنک سازی فیلم پره..........................................................................................................................76

-نسبت دمش.................................................................................................................................86

-انحنای سطح................................................................................................................................87

-گرادیان فشار...............................................................................................................................88

-آشفتگی جریان اصلی...................................................................................................................89

-شیارهای خنک سازی فیلم...........................................................................................................91

-تجمع فیلم.................................................................................................................................92

-تاثیر تزریق هوای خنک سازی فیلم روی انتقال حرارت سطح......................................................94

موضوعات خنک سازی دیواره نهایی....................................................................................................95

تحقیق درباره سرطان پوست

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Causes of skin cancer

Ultraviolet light from the sun is the main cause of skin cancer. Skin cancer is becoming more common and there are several possible reasons for this. People are living longer (and so their lifetime sun exposure is greater). They often have more time and money for outdoor recreation and holidays in sunny climates and many people still consider suntans to be healthy and attractive. It is likely that most skin damage from ultraviolet radiation occurs before the age of 20. It is thought that a build-up of overexposure to the sun over a period of several years can lead to the development of basal cell and squamous cell skin cancers.

Black- or brown-skinned people have a very low risk of developing skin cancer because the melanin pigment in their skin gives them protection. A fair-skinned person who tends to go red or freckle in the sun will be most at risk. Children and young adults who have been overexposed to the sun have an increased risk of developing some form of skin cancer. This will not show up until later on in life – usually after about age 40, and often not until the 60s or 70s.

The regular use of sunlamps and sunbeds increases the risk of developing skin cancer.

Areas of skin that have been badly burned, or have long-term inflammation have an increased risk of squamous cell carcinoma.

Radiotherapy given to treat other conditions can sometimes cause skin cancers in the treatment area later in life.

People who have to take drugs which lower their immunity (immunosupressants) – for example, after a kidney transplant – are also at increased risk of getting skin cancer.

Other rare possible causes are overexposure to certain chemicals at work, including coal tar, soot, pitch, asphalt, creosotes, paraffin waxes, petroleum derivatives, hair dyes, cutting oils and arsenic. You should wear protective clothing if you are handling these substances frequently.

Some people with rare hereditary conditions have a higher risk of developing skin cancer. However, non-melanoma skin cancers are not caused by inherited faulty genes that can be passed on to other family members and so other members of your family are not at a higher risk of developing skin cancer.

What are the symptoms?

Both basal cell and squamous cell carcinomas can appear in a variety of forms.

Basal cell cancers can develop as a small lump on your skin which is smooth and pearly or waxy in appearance. It may bleed sometimes or develop a crust. It may begin to show signs of healing and yet never quite does. Instead, you may see a flat, red spot, which is scaly and crusty. Sometimes there is just a firm, red lump. Skin cancers are usually painless and grow slowly. They can appear anywhere on your body but are most likely to occur on exposed skin, especially your face.

Squamous cell carcinomas often have a scaly appearance. Sometimes they have a hard, horny cap and can feel tender to touch. They are also found on the face, bald scalps, arms, backs of hands and lower legs.

If you notice anything unusual on your skin which does not go away within a month, you should show it to your doctor. There are, however, many other conditions that may appear in the skin which are not cancer, particularly among older people. You may still wish to have these treated for cosmetic reasons.

Signs and symptoms of non-melanoma skin cancer:

Most likely to appear on face, neck or other exposed skin. 

Small lump- smooth or waxy- may bleed- may develop a crust - may be itchy

Flat, red spot -- scaly and crusty

Firm, red lump -- painless, growing slowly

Lump with scaly or horny top

How it is diagnosed

Usually you begin by seeing your GP (family doctor), who will examine you and decide whether to refer you to a hospital specialist for further tests and treatment. A specialist in skin diseases is called a dermatologist. Your treatment may be carried out by the dermatologist. Depending on the area of the body affected by the cancer and the type of treatment that is necessary you may be referred to a general surgeon, a plastic surgeon or a clinical oncologist (radiotherapy and chemotherapy specialist).

The specialist will be able to tell a great deal from a simple examination of the affected area of skin. However, it is not always possible to distinguish between skin cancers and benign conditions by examination alone. You may be advised to have a biopsy. This is a quick and simple procedure which can usually be done in the outpatients department using a local anaesthetic. The doctor will remove all or part of the lump and send it to the laboratory for analysis under a microscope by a pathologist.

As basal cell carcinomas almost never spread, there will probably be no need for further tests as long as the cancer has been completely removed.

As squamous cell carcinomas may occasionally spread, your doctor may want to do one or two other tests as well as the physical examination and biopsy. This is to make sure that there is no need for further treatment. The tests are particularly important if you have had treatment for skin cancer before and it has come back (recurred). During the physical examination, the doctor will probably feel the lymph glands close to the cancer to see if any of them are enlarged. You will probably be asked to have a chest x-ray and possibly blood tests to assess your general health. If any other tests are necessary your doctor will discuss these with you

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مقاله درباره Quality of Wood

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تعداد صفحات: 8

Quality of Wood

Just Kids Stuff has been hand crafting quality products for overQ thirty years and specializes in all wood, hand crafted children's furniture. We offer toddler beds in several fun styles, furniture, toys, and toy boxes that are the perfect size for toddlers. Kids' safety is our priority, so all of our products are tough, sturdy and kid approved!All of our products are built for real kids in the real world. Some of our beds and toy boxes have been in use for two generations. My kids are farm kids and couldn't tear them up. They are built to pass on to your grandchildren.

Our toddler beds are all wood construction - hand crafted from imported laminated Baltic birch and other solid woods. No Medium Density Fiberboard (MDF) is used. They all take a standard sized crib mattress for the ultimate in comfort (and fun) for your little one. Kids love having a special kid sized bed and they like the security of a little bed rather than being put in a full sized bed.All of the toddler Beds measure 53 x 29 inches outside, and one inch smaller on the inside. The entrances are 12 - 13 inches above the floor.All of our Toddler Beds and Toy Boxes are built in the U.S.A. and have a lead free lacquer finish.

We drop ship and ship worldwide. Please call for shipping costs outside of the continental USA.

Welcome to Quality Wood Products Online Catalog. Within our site you will find pages upon pages of samples of the scrollsawing and woodwork we do. Most of it is finished, but we can provide you decorative painters and artists out there the raw wood to build upon. Let your imagination run wild. But we offer more than that. For you newbies to the scrollsaw we offer our own tips, tricks, and techniques for getting the most out of your scrollsaw. We have also scoured the Net looking for scrollsaw related sites and provided links for those also. We are also members of the Scrollsaw Webring. If you are interested in scrollsawing you can see what some other scrollsaw artists are doing. For you woodworkers out there we have provided links to sites on the WWW that offer free woodworking patterns. For crafters of all persuasions we offer links to some of the most active and helpful craft related message boards on the Web. We also have links to free craft patterns and projects on the Web and places to find where craft shows are happening in your neck of the woods (we also have our show schedule online with maps on how to get there in case you want to see us in person!). So please, poke around our site for awhile. There is a link to our personal home page (if you want to get to know us a little), a link to information about QWP and our history and if you want to share what you see with a friend just click on file and send this page to a friend.

Sign Guestbook View Guestbook We realize you can't comment on our site until you've seen it. So,after browsing our site please take the time sign our Guest-Book. Any comments, criticisms, or suggestions are welcome

Simple ways to check

wood pellet quality

Pieter D. Kofman

© 07ocessing / Products No. 11

The quality of wood pellets can vary greatly. When buying wood pellets one

دیدگاهی متفاوت ازفراگیری سازمانی

اختصاصی از اینو دیدی دیدگاهی متفاوت ازفراگیری سازمانی دانلود با لینک مستقیم و پر سرعت .

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A Differal view of organization learing

دیدگاهی متفاوت ازفراگیری سازمانی

گردآورنده : سوگیلی

به نظرمی رسد بیشترادبیات فراگیری سازمانی ،دنباله روی عقاید(اصول) تئوریهای فراگیری وجنبۀ فکری فردی یاروانشناسانه برروی این پدیده هستند . مباحثه ای دراین موردوجودداردکه آیاسازماندهی هامی توانندیادبگیرندیاخیروبسیاری فقط درراه رسیدن به آن هستند. که فراگیری سازمانی ،حاصل جمع فراگیری فردی است ، که درمحل کارروی می دهد .

(Argris &schon , 1996 ; levit & March,1998; Normann,1985

;Weick&Westly,1996).

اگرتمرکزمابه یکی که انسان شناسانه تراست ودرنتیجه برروی فراگیری گروه تمرکزی می یابد،تغییرکند،چه اتفاقی روی می دهد؟اگرتغییری ازفراگیری دریافت شده به اندازۀ درک برای فهم آن وجودداشت ،چه اتفاقی می افتاددرزمانیکه ،گروههاسعی می کنند ،احساسی خارج ازدنیایشان بسازند؟ .

به عنوان نتیجۀ دیدگاه جدیدفراگیری سازمانی ،چه چیزی می تواند ،بعضی ازتغییرات ضروری دراین دیدگاهها،عقایدیاتمرینات باشد؟ چراشرکتهامی خواهند. سازمان های فراگیری باشند ؟ این صفحه این ،قضایاراجستجوخواهدکرد .

این امر،مشکل به نظرمی رسد،که دیدگاههای یادگیری مان رابه بعضی ازگروههایی که آن راانجام می دهند ،تغییردهیم . واینکه این کاربخشی طبیعی ازفعالیت روزمره مان است . بسیاری ازمربیان ومتخصصان علوم نظری به نظرنمی رسدکه قادربه شنیدن تکذیبات خودشان باشند .

Jamese .Russel ,dean emeritus ,Teachers college,colum bia university بیان می کند .

این امرنمی تواند،اغلب هدف قرارداده شودکه همۀ تحصیلات ،خودتحصیلی هستند . ممکن است آموزگاران به محدودکردن فرآیندرسوم ،جمع آوری تجهیزات ونشان دادن آرام ترین مسیرهاکمک کنند ،اماصعودکننده بایدبرای رسیدن به قلۀ کوه ،سروپاهای خودش رابکارببرد. بدون تردید،بهترین روش برای تدریس بزرگسالان ،بحث گروهی است . (Knowles ,1990 )

روش تئوری گروهی به فراگیری خیلی همدردبافراگیری نوع بشری است ، اماحتی چارلزراجردرکتاب آزادی یادگیری اش بطورمستقیم یادگیری گروه رابیان نمی کند .

مرجعی به نام jigsaw opproach (تئوری زیگسار) وجودداردکه ، هردانش آموزرابه عنوان قطعه ای تعیین می کند که قسمتی ازکل پروژه می شود . اگرمایادگیری گروهی رابه عنوان چیزهای متفاوت ازذخیره یادگیری فردی جستجوکنیم ،سقوط کوتاهی ازچیزی که ممکن است باشد ،بنظرمی رسد .

چه اتفاقی می افتداگرکارگران ازکاردسته جمعی وکمک به یک نفردیگردرخواست کمک می کند ،همدستی ، وازانجام کارواقعی بایکدیگردوری کنند؟ این صفحه درمورداین قضیه بحث نمی کند که آیاچنین چیزی به عنوان یادگیری گروهی وجودداردیاخیروجودندارد. درعوض به مااجازه می دهدکه فقط سعی کنیم که ببینیم که چه چیزی می تواند زمانی که مادیدگاهی متفاوت ازموضوع داریم دربارۀ یادگیری سازمانی کشف شده باشد .

مفهوم های کلیدی (اصلی) برای توسعۀ دیدگاه متفاوت ازیادگیری سازمانی ابتداء ازسه ضلع نشأت می گیرد . دریکی ازمقالات ،نویسندگان سازمان رابه عنوان یک فرهنگ وپیوستگی نظم وبی نظمی ،که اغلب یادگیری راتحریک می کند ،می بینند .

(weick &westly ,1996)

دومین بازسازی اجتماعی دانستنیهادرگروههااینکه وچگونه این امر،راهی که بایدیادگیری رامی فهمیم تغییرمی دهد،توجه می کنند (Bruffee.1993

سومین منبع ، چرخۀ طبی آمریکاییهای بومی رابکارمی بردکه یک مدل یادگیری سازمانی راکه مدور،طولانی وتکامل یافته ،بیش ازمسیرمعمولی اند وبرش متقاطع وقسمتی راتوسعه می دهد . یادگیری چیزی است که تمام اوقات اتفاق می افتد (Cowan,1995)

سپس این مفاهیم نشأت گرفته ،ازاین سه منبع کلیدی برای فهمیدن اینکه آنهاچه چیزی برای یادگیری سازمانی نشان می دهند گسترده می شوند . پس،بعضی ازتغییرات لازم سازمانهاممکن است به منظورپذیرش این مفهوم های رسیدگی شده ،ساخته شود .

Organizational culture

فرهنگ سازمانی

دریک مقاله توسط ویک وستلی درکتاب مطالعات سازماندهی درسال (1996) که یادگیری سازمانی نامیده شد . درحال اظهارکردن یک oxymoron(یعنی : عباراتی که دوکلمه راترکیب می کند تابرضدیکدیگرباشند ، نویسندگان سازمانهارابه اندازۀ فرهنگهامی دانند .آنهاتوضیح می دهند که یادگیری سازمانی یک oxymoro است . زیرایادگیری ،اختلال ویک افزایش رادرتنوع درگیرمی کند ، درحالیکه سازماندهی غفلت ویک کاهش رادرتنوع درگیرمی کند . این امتدادی راسازماندهی می کند که بسیاری ازکارگران بکارنمی برند واغلب دریک تلاش برای برگشتن به سازماندهی نادیده می گیرند .

تحقیق و بررسی در مورد سرطان پوست

اختصاصی از اینو دیدی تحقیق و بررسی در مورد سرطان پوست دانلود با لینک مستقیم و پر سرعت .

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تعداد صفحات: 2

Causes of skin cancer

Ultraviolet light from the sun is the main cause of skin cancer. Skin cancer is becoming more common and there are several possible reasons for this. People are living longer (and so their lifetime sun exposure is greater). They often have more time and money for outdoor recreation and holidays in sunny climates and many people still consider suntans to be healthy and attractive. It is likely that most skin damage from ultraviolet radiation occurs before the age of 20. It is thought that a build-up of overexposure to the sun over a period of several years can lead to the development of basal cell and squamous cell skin cancers.

Black- or brown-skinned people have a very low risk of developing skin cancer because the melanin pigment in their skin gives them protection. A fair-skinned person who tends to go red or freckle in the sun will be most at risk. Children and young adults who have been overexposed to the sun have an increased risk of developing some form of skin cancer. This will not show up until later on in life – usually after about age 40, and often not until the 60s or 70s.

The regular use of sunlamps and sunbeds increases the risk of developing skin cancer.

Areas of skin that have been badly burned, or have long-term inflammation have an increased risk of squamous cell carcinoma.

Radiotherapy given to treat other conditions can sometimes cause skin cancers in the treatment area later in life.

People who have to take drugs which lower their immunity (immunosupressants) – for example, after a kidney transplant – are also at increased risk of getting skin cancer.

Other rare possible causes are overexposure to certain chemicals at work, including coal tar, soot, pitch, asphalt, creosotes, paraffin waxes, petroleum derivatives, hair dyes, cutting oils and arsenic. You should wear protective clothing if you are handling these substances frequently.

Some people with rare hereditary conditions have a higher risk of developing skin cancer. However, non-melanoma skin cancers are not caused by inherited faulty genes that can be passed on to other family members and so other members of your family are not at a higher risk of developing skin cancer.

What are the symptoms?

Both basal cell and squamous cell carcinomas can appear in a variety of forms.

Basal cell cancers can develop as a small lump on your skin which is smooth and pearly or waxy in appearance. It may bleed sometimes or develop a crust. It may begin to show signs of healing and yet never quite does. Instead, you may see a flat, red spot, which is scaly and crusty. Sometimes there is just a firm, red lump. Skin cancers are usually painless and grow slowly. They can appear anywhere on your body but are most likely to occur on exposed skin, especially your face.

Squamous cell carcinomas often have a scaly appearance. Sometimes they have a hard, horny cap and can feel tender to touch. They are also found on the face, bald scalps, arms, backs of hands and lower legs.

If you notice anything unusual on your skin which does not go away within a month, you should show it to your doctor. There are, however, many other conditions that may appear in the skin which are not cancer, particularly among older people. You may still wish to have these treated for cosmetic reasons.

Signs and symptoms of non-melanoma skin cancer:

Most likely to appear on face, neck or other exposed skin. 

Small lump- smooth or waxy- may bleed- may develop a crust - may be itchy

Flat, red spot -- scaly and crusty

Firm, red lump -- painless, growing slowly

Lump with scaly or horny top

How it is diagnosed

Usually you begin by seeing your GP (family doctor), who will examine you and decide whether to refer you to a hospital specialist for further tests and treatment. A specialist in skin diseases is called a dermatologist. Your treatment may be carried out by the dermatologist. Depending on the area of the body affected by the cancer and the type of treatment that is necessary you may be referred to a general surgeon, a plastic surgeon or a clinical oncologist (radiotherapy and chemotherapy specialist).

The specialist will be able to tell a great deal from a simple examination of the affected area of skin. However, it is not always possible to distinguish between skin cancers and benign conditions by examination alone. You may be advised to have a biopsy. This is a quick and simple procedure which can usually be done in the outpatients department using a local anaesthetic. The doctor will remove all or part of the lump and send it to the laboratory for analysis under a microscope by a pathologist.

As basal cell carcinomas almost never spread, there will probably be no need for further tests as long as the cancer has been completely removed.

As squamous cell carcinomas may occasionally spread, your doctor may want to do one or two other tests as well as the physical examination and biopsy. This is to make sure that there is no need for further treatment. The tests are particularly important if you have had treatment for skin cancer before and it has come back (recurred). During the physical examination, the doctor will probably feel the lymph glands close to the cancer to see if any of them are enlarged. You will probably be asked to have a chest x-ray and possibly blood tests to assess your general health. If any other tests are necessary your doctor will discuss these with you

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