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中国六派建筑特点英语介绍Chinese architectural styles can be broadly classified into six main categories, known as the Six Schools of Chinese Architecture. Each school has its unique characteristics and features.1. Ancient Architecture (古代建筑): This style focuses on harmony with nature and emphasizes a balanced layout. It often incorporates elements like courtyards, wooden structures, and grey-green glazed roof tiles.2. Buddhist Architecture (佛教建筑): Influenced by Buddhist philosophy, this style is characterized by grand and elaborate structures, with intricate carvings and sculptures of deities. It often features pagodas, temples, and monasteries.3. Imperial Chinese Architecture (宫殿式建筑): This style is closely associated with the imperial dynasties and emphasizes power and authority. It is known for its majestic palaces, sprawling gardens, and precise symmetry. The Forbidden City in Beijing is a prime example of this style.4. Ethnic Minority Architecture (少数民族建筑): China is home toa diverse range of ethnic groups, each with their own architectural traditions. Ethnic minority architecture often features vibrant colors, intricate patterns, and unique structural designs that reflect their cultural identities.5. Garden Architecture (园林建筑): Chinese gardens are famous for their meticulous design and poetic beauty. They are often builtaround natural landscapes, with carefully arranged pavilions, bridges, and water features. Suzhou and Hangzhou are well-known for their classical gardens.6. Modern Chinese Architecture (现代建筑): With the rapid urbanization and economic growth in China, modern architectural styles have emerged. These include contemporary high-rises, avant-garde designs, and innovative urban planning. Examples include the iconic Bird's Nest stadium in Beijing and Shanghai's futuristic skyline.In conclusion, the Six Schools of Chinese Architecture offer a fascinating variety of styles, each reflecting different cultural, religious, and historical influences. From ancient wooden structures to grand imperial palaces, Chinese architecture is a testament to the country's rich heritage and evolving identity.。
关于建筑风格英语作文The Influence of Architectural Styles。
Architecture is an art form that has been evolving for centuries. From the ancient pyramids of Egypt to the modern skyscrapers of New York City, the world of architecture is as diverse as the cultures and civilizations that have created it. Throughout history, different architectural styles have emerged, each with its own unique characteristics and influences. These styles not only reflect the aesthetic preferences of a particular time and place, but also the social, cultural, and technological developments of the era. In this essay, we will explore the influence of architectural styles on the built environment and the ways in which they shape our experiences and perceptions of space.One of the most enduring architectural styles is classical architecture, which originated in ancient Greece and Rome. Characterized by its use of columns, arches, andpediments, classical architecture has had a profound impact on the design of buildings throughout the Western world.Its emphasis on symmetry, proportion, and harmony has beena source of inspiration for architects and designers for centuries. The enduring appeal of classical architecturecan be seen in the countless government buildings, museums, and monuments that continue to be built in this style today.In contrast to the formal and symmetrical nature of classical architecture, the Gothic style emerged inmedieval Europe as a response to the growing power and influence of the Catholic Church. Gothic cathedrals, with their soaring spires, pointed arches, and intricate stained glass windows, were designed to inspire awe and reverencein the faithful. The Gothic style is also known for its use of ribbed vaults and flying buttresses, which allowed forthe construction of taller and more expansive buildings.The influence of Gothic architecture can be seen in the design of many of Europe's most iconic landmarks, including Notre Dame Cathedral in Paris and the Duomo in Milan.As the world entered the modern era, new architecturalstyles began to emerge that reflected the changing social and technological landscape. The industrial revolution brought about a shift towards functionalism and efficiency, leading to the rise of the modernist movement. Modernist architects such as Le Corbusier and Ludwig Mies van der Rohe sought to create buildings that were sleek, minimalist, and free from historical ornamentation. The use of new materials such as steel and glass allowed for the construction of buildings with open floor plans and large expanses of windows, blurring the boundaries betweeninterior and exterior space. The influence of modernist architecture can be seen in the design of many of theworld's most iconic skyscrapers, such as the SeagramBuilding in New York City and the Sydney Opera House in Australia.In recent decades, a renewed interest in traditional architectural styles has emerged, as architects and designers seek to create buildings that are more in harmony with their natural and cultural surroundings. This has ledto a resurgence of interest in vernacular architecture, which draws inspiration from local building traditions andmaterials. The use of sustainable and environmentally friendly building practices has also become a priority for many architects, leading to the rise of green and eco-friendly architecture.In conclusion, the influence of architectural styles on the built environment is profound and far-reaching. From the grandeur of classical architecture to the innovation of modernist design, each style reflects the values and aspirations of the society that created it. As we continue to evolve and adapt to the challenges of the 21st century, it is clear that architecture will continue to play a vital role in shaping our experiences and perceptions of the world around us.。
中外建筑对比英语作文Title: A Comparative Analysis of Chinese and Western Architecture。
Architecture serves as a reflection of culture, history, and societal values. Comparing Chinese and Western architecture offers insight into the distinctcharacteristics and influences of each. In this essay, we will explore the differences between the two architectural styles, highlighting their unique features, historical contexts, and cultural significance.Historical Context。
Chinese architecture has a rich history dating back thousands of years, with influences from various dynasties and cultural exchanges. Traditional Chinese architecture is characterized by its emphasis on harmony with nature, symmetry, and meticulous craftsmanship. Key architectural elements include curved roofs, wooden structures, andintricate ornamentation, often influenced by Confucian, Taoist, and Buddhist philosophies.On the other hand, Western architecture has its roots in ancient Greece and Rome, with significant influences from the Renaissance, Baroque, and Neoclassical periods. Western architecture prioritizes principles of proportion, perspective, and symmetry. Architectural marvels such as the Parthenon, Colosseum, and Gothic cathedrals exemplify the grandeur and innovation of Western architectural achievements.Architectural Styles and Characteristics。
我想成为一名建筑工程师英语作文As an aspiring architect, I am truly captivated by the dynamic and transformative power of buildings. Fromintricate design concepts to the execution of complex construction projects, the world of architecture offers a unique blend of creativity and technical prowess. In this essay, I will delve into my passion for becoming a successful architectural engineer.To commence, my journey towards becoming an architect begins with a firm foundation in education. A strong background in mathematics, physics, and art has laid the groundwork for my understanding of structures, aesthetics, and spatial planning. Drawing inspiration from historical landmarks and contemporary architectural masterpieces, I have acquired an appreciation for diverse architectural styles that shape our cities and cultures.Furthermore, I firmly believe that creativity is at the forefront of architectural excellence. Just as every artist has their own unique style, every architect possesses theirdistinct design philosophy. It is through imagination and innovation that architects can create functional spacesthat also evoke emotions and inspire people's lives. By constantly challenging conventional norms and thinking beyond boundaries, architectural engineers have the ability to redefine possibilities.Equally important as creativity is sustainability in contemporary architecture. As we face global environmental challenges, such as climate change and dwindling resources, architects bear a responsibility to create eco-friendly structures that minimize carbon footprint while maximizing energy efficiency. This not only presents an exciting challenge but also underscores the profound impact architecture can have on our planet's future.Apart from theoretical knowledge, practical experience plays a crucial role in honing one's architectural skills. Working with renowned architects or interning at reputable architecture firms will enable me to bridge the gap between academic learning and real-world applications. It is in these opportunities where I hope to refine my technicalexpertise while grasping invaluable insights into collaborative processes within multidisciplinary teams.Moreover, embracing technology is essential for staying ahead in today's digital era. With advancements such as Building Information Modeling (BIM) and computational design tools, architects can visualize and simulate designs with greater accuracy and efficiency. Embracing these technological advancements will allow me to push the boundaries of design and construction, ensuring that the final built environment is not only visually striking but also practical and sustainable.In conclusion, my desire to become a qualifiedarchitectural engineer stems from a profound admiration for the power and influence this profession wields. By fusing creativity, sustainability, practical experience, and technological proficiency, I am confident that I can contribute to shaping our built environment in a way that both inspires and stands the test of time. With unwavering dedication and continuous learning, I am ready to embark onthis fulfilling journey towards becoming an accomplished architect.。
说一说古代房屋与现代房屋的差异英语作文In exploring the disparities between ancient and modern dwellings, it is fascinating to delve into the architectural aspects that define each era. While modern housing reflects technological advancements, efficiency, and aesthetic preferences, ancient homes were a product of their time, designed with different priorities in mind.One noticeable difference lies in the materials used for construction. Modern houses often employ steel, concrete, and glass due to their durability and versatility. In contrast, ancient dwellings relied heavily on locally available resources like wood, stone, mud bricks or even animal hides. These materials varied according to geographic location and the culture of the inhabitants.Another disparity pertains to the design and layout of the dwellings. In ancient times, houses were primarily single-story structures built around a central courtyard or open space. This design facilitated communal living andemphasized social interaction within the household. On the other hand, modern houses tend to have multiple floors or levels, with rooms devoted to specific purposes like living areas, bedrooms, kitchens, and bathrooms. The emphasis now often lies in privacy and personal spaces.Furthermore, energy consumption has become a significant concern in modern housing design. Modern homes are equipped with various energy-efficient technologies such as solar panels for electricity generation and insulation materials for temperature control. Additionally, innovative smart home systems enable homeowners to monitor and manage energy usage effectively. In contrast, ancient homes relied on natural ventilation methods such as high ceilings or strategically placed windows for cooling or heating purposes.The amenities available within each type of dwelling also differ significantly. Modern houses typically come equipped with all necessary facilities including plumbing systemsfor running water supply, centralized heating and cooling systems for comfortable living conditions throughout theyear. Ancient homes lacked such conveniences; instead they often had communal wells or relied on nearby natural sources for water supply while using fireplaces for warmth.Lastly, we cannot ignore how architecture reflects cultural values and influences societal norms over time. Ancient architecture celebrated traditions deeply ingrained inlocal cultures and reflected social hierarchies. Modern houses, however, are often a reflection of globalization and the blending of various architectural styles from around the world. This diversity reflects our current globalized society and offers a range of options for individuals to choose from.In conclusion, it is evident that ancient and modern housing showcase distinct characteristics in terms of materials used, designs employed, energy consumption practices, amenities available, as well as cultural influences. While modern housing caters to the individual's need for comfort and sustainability, ancient dwellings were designed with communal living and cultural traditions in mind. By understanding these differences, we can appreciatethe evolution of architecture throughout human history and gain insights into our own living spaces.。
OFFSHORE STANDARDD ET N ORSKE VERITASDNV-OS-C201STRUCTURAL DESIGN OF OFFSHOREUNITS (WSD METHOD)APRIL 2005Since issued in print (April 2005), this booklet has been amended, latest in April 2006.See the reference to “Amendments and Corrections” on the next page.Comments may be sent by e-mail to rules@For subscription orders or information about subscription terms, please use distribution@Comprehensive information about DNV services, research and publications can be found at http :// , or can be obtained from DNV,Veritasveien 1, NO-1322 Høvik, Norway; Tel +47 67 57 99 00, Fax +47 67 57 99 11.© Det Norske Veritas. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopying and recording, without the prior written consent of Det Norske puter Typesetting (FM+SGML) by Det Norske Veritas.Printed in Norway.If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas, then Det Norske Veritas shall pay compensation to such person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided that the maximum compen-sation shall never exceed USD 2 million.In this provision "Det Norske Veritas" shall mean the Foundation Det Norske Veritas as well as all its subsidiaries, directors, officers, employees, agents and any other acting on behalf of Det Norske Veritas.FOREWORDDET NORSKE VERITAS (DNV) is an autonomous and independent foundation with the objectives of safeguarding life, prop-erty and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification and consultancy services relating to quality of ships, offshore units and installations, and onshore industries worldwide, and carries out research in relation to these functions.DNV Offshore Codes consist of a three level hierarchy of documents:—Offshore Service Specifications. Provide principles and procedures of DNV classification, certification, verification and con-sultancy services.—Offshore Standards. Provide technical provisions and acceptance criteria for general use by the offshore industry as well asthe technical basis for DNV offshore services.—Recommended Practices. Provide proven technology and sound engineering practice as well as guidance for the higher levelOffshore Service Specifications and Offshore Standards.DNV Offshore Codes are offered within the following areas:A)Qualification, Quality and Safety Methodology B)Materials Technology C)Structures D)SystemsE)Special Facilities F)Pipelines and Risers G)Asset Operation H)Marine Operations J)Wind TurbinesAmendments and CorrectionsThis document is valid until superseded by a new revision. Minor amendments and corrections will be published in a separate document normally updated twice per year (April and October).For a complete listing of the changes, see the “Amendments and Corrections” document located at: /technologyservices/, “Offshore Rules & Standards”, “Viewing Area”.The electronic web-versions of the DNV Offshore Codes will be regularly updated to include these amendments and corrections.Amended April 2006,Offshore Standard DNV-OS-C201, April 2005 see note on front cover Changes – Page 3Changes April 2005—Sec.1. Unification of requirements, level of references, terms, definitions, lay-out, text, etc. with the LRFD stand-ards, i.e. general standard (DNV-OS-C101), the standards for various objects (DNV-OS-C102 to DNV-OS-C106), as well as the fabrication standard (DNV-OS-C401). —Sec.1 & Sec.2. Definition and application of design tem-perature and service temperature has been updated, and the terminology co-ordinated with the LRFD standards.—Sec.4. Overall conditions for fracture mechanics (FM) testing, and post weld heat treatment (PWHT) transferred here (from DNV-OS-C401). Requirements to FM adjusted to reflect results of more recent research work. —Sec.5. References to the more recent Recommended Prac-tices introduced e.g. DNV-RP-C201 (for Plates), updating references to CN 30.1.—Sec.3 D300. Specified tank pressures are harmonised with similar formulas in the LRFD standards, while simultane-ously attempted simplified and clarified.—Sec.11 to Sec.14. (Ref. to the various objects.) Formulas for sea pressure during transit are reorganised and clari-fied, improving readability.—Sec.12. Text covering redundancy and detailed design re-vised in line with DNV-OS-C104 (and the previous MOU-rules).—Sec.13. Text regarding the topics of tendon fracture me-chanics, composite tendons, and stability, as well as the CMC requirements are all updated, bringing the text in line with most recent revision of DNV-OS-C105.—Sec.14. Text updated in line with ongoing revision of DNV-OS-C106.D ET N ORSKE V ERITASOffshore Standard DNV-OS-C201, April 2005Amended April 2006, Page 4 – Changes see note on front coverD ET N ORSKE V ERITASAmended April 2006,Offshore Standard DNV-OS-C201, April 2005 see note on front cover Contents – Page 5CONTENTSSec. 1Introduction (9)A.General (9)A100Introduction (9)A200Objectives (9)A300Scope and application (9)A400Other than DNV codes (9)A500Classification (9)B.References (9)B100General (9)C.Definitions (10)C100Verbal forms (10)C200Terms (10)D.Abbreviations and Symbols (12)D100Abbreviations (12)D200Symbols (12)Sec. 2Design Principles (15)A.Introduction (15)A100General (15)A200Aim of the design (15)B.General Design Considerations (15)B100General (15)B200Overall design (15)B300Details design (15)C.Design Conditions (15)C100Basic conditions (15)D.Loading Conditions (16)D100General (16)D200Load (16)E.Design by the WSD Method (16)E100Permissible stress and usage factors (16)E200Basic usage factors (16)F.Design Assisted by Testing (16)F100General (16)F200Full-scale testing and observation of performance of existing structures (16)Sec. 3Loads and Load Effects (17)A.Introduction (17)A100General (17)B.Basis for Selection of Loads (17)B100General (17)C.Permanent Functional Loads (17)C100General (17)D.Variable Functional Loads (18)D100General (18)D200Variable functional loads on deck areas (18)D300Tank pressures (18)D400Lifeboat platforms (19)E.Environmental Loads (19)E100General (19)E200Environmental conditions for mobile units (19)E300Environmental conditionss for site specific units (19)E400Determination of hydrodynamic loads (19)E500Wave loads (19)E600Wave induced inertia forces (20)E700Current (20)E800Wind loads (20)E900Vortex induced oscillations (20)E1000Water level and tidal effects (20)E1100Marine growth (20)E1200Snow and ice accumulation............................................20E1300Direct ice load.. (20)E1400Earthquake (20)bination of Environmental Loads (21)F100General (21)G.Accidental Loads (21)G100General (21)H.Deformation Loads (21)H100General (21)H200Temperature loads (21)H300Settlements and subsidence of sea bed (21)I.Fatigue loads (22)I100General (22)J.Load Effect Analysis (22)J100General (22)J200Global motion analysis (22)J300Load effects in structures and soil or foundation (22)Sec. 4Structural Categorisation, Material Selection and Inspection Principles (23)A.General (23)A100 (23)B.Temperatures for Selection of Material (23)B100General (23)B200Floating units (23)B300Bottom fixed units (23)C.Structural Category (23)C100General (23)C200Selection of structural category (23)C300Inspection of welds (24)D.Structural Steel (24)D100General (24)D200Material designations (24)D300Selection of structural steel (25)D400Fracture mechanics (FM) testing (25)D500Post weld heat treatment (PWHT) (25)Sec. 5Structural Strength (26)A.General (26)A100General (26)A200Structural analysis (26)A300Ductility (26)A400Yield check (26)A500Buckling check (27)B.Flat Plated Structures and Stiffened Panels (27)B100Yield check (27)B200Buckling check (27)B300Capacity checks according to other codes (27)C.Shell Structures (27)C100General (27)D.Tubular Members, Tubular Joints and Conical Transitions.27 D100General (27)E.Non-Tubular Beams, Columns and Frames (28)E100General (28)Sec. 6Section Scantlings (29)A.General (29)A100Scope (29)B.Strength of Plating and Stiffeners (29)B100Scope (29)B200Minimum thickness (29)B300Bending of plating (29)D ET N ORSKE V ERITASOffshore Standard DNV-OS-C201, April 2005Amended April 2006, Page 6 – Contents see note on front coverB400Stiffeners (29)C.Bending and Shear in Girders (30)C100General (30)C200Minimum thickness (30)C300Bending and shear (30)C400Effective flange (30)C500Effective web (30)C600Strength requirements for simple girders (30)C700Complex girder systems (31)Sec. 7Fatigue (32)A.General (32)A100General (32)A200Design fatigue factors (32)A300Methods for fatigue analysis (32)A400Simplified fatigue analysis (33)A500Stochastic fatigue analysis (33)Sec. 8Accidental Conditions (34)A.General (34)A100General (34)B.Design Criteria (34)B100General (34)B200Collision (34)B300Dropped objects (34)B400Fires (34)B500Explosions (34)B600Unintended flooding (34)Sec. 9Weld Connections (36)A.General (36)A100Scope (36)B.Types of Welded Steel Joints (36)B100Butt joints (36)B200Tee or cross joints (36)B300Slot welds (37)B400Lap joint (37)C.Weld Size (37)C100General (37)C200Fillet welds (37)C300Partly penetration welds and fillet welds in crossconnections subject to high stresses (38)C400Connections of stiffeners to girders and bulkheads, etc..38 C500End connections of girders (39)C600Direct calculation of weld connections (39)Sec. 10Corrosion Control (40)A.General (40)A100Scope (40)B.Techniques for Corrosion Control Related to EnvironmentalZones (40)B100Atmospheric zone (40)B200Splash zone (40)B300Submerged zone (40)B400Internal zone (40)C.Cathodic Protection (41)C100General (41)C200Galvanic anode systems (41)C300Impressed current systems (42)D.Coating Systems (42)D100Specification of coating (42)Sec. 11Special Considerations for Column Stabilised Units (43)A.General (43)A100Assumptions and application (43)B.Structural Categorisation, Material Selection and InspectionPrinciples (43)B100General (43)B200Structural categorisation (43)B300Material selection (43)B400Inspection categories (44)C.Design and Loading Conditions (46)C100General (46)C200Permanent loads (46)C300Variable functional loads (46)C400Tank loads (46)C500Environmental loads, general (46)C600Sea pressures (47)C700Wind loads (47)C800Heavy components (47)C900Combination of loads (47)D.Structural Strength (47)D100General (47)D200Global capacity (47)D300Transit condition (47)D400Method of analysis (48)D500Air gap (48)E.Fatigue (48)E100General (48)E200Fatigue analysis (49)F.Accidental Conditions (49)F100General (49)F200Collision (49)F300Dropped objects (49)F400Fire (49)F500Explosion (49)F600Heeled condition (49)G.Redundancy (49)G100General (49)G200Brace arrangements (49)H.Structure in Way of a Fixed Mooring System (49)H100Structural strength (49)I.Structural Details (50)I100General (50)Sec. 12Special Considerations forSelf-Elevating Units (51)A.Introduction (51)A100Scope and application (51)B.Structural Categorisation, Material Selection and InspectionPrinciples (51)B100General (51)B200Structural categorisation (51)B300Material selection (51)B400Inspection categories (51)C.Design and Loading Conditions (51)C100General (51)C200Transit (52)C300Installation and retrieval (52)C400Operation and survival (52)D.Environmental Conditions (53)D100General (53)D200Wind (53)D300Waves (53)D400Current (53)D500Snow and ice (53)E.Method of Analysis (53)E100General (53)E200Global structural models (54)E300Local structural models (54)E400Fatigue analysis (55)F.Design Loads (55)F100General (55)F200Permanent loads (55)D ET N ORSKE V ERITASAmended April 2006,Offshore Standard DNV-OS-C201, April 2005 see note on front cover Contents – Page 7F300Variable functional loads (55)F400Tank loads (55)F500Environmental loads, general (55)F600Wind loads (55)F700Waves (56)F800Current (56)F900Wave and current (56)F1000Sea pressures during transit (57)F1100Heavy components during transit (57)F1200Combination of loads (57)G.Structural Strength (57)G100General (57)G200Global capacity (57)G300Footing strength (57)G400Leg strength (58)G500Jackhouse support strength (58)G600Hull strength (58)H.Fatigue Strength (58)H100General (58)H200Fatigue analysis (58)I.Accidental Conditions (58)I100General (58)I200Collisions (58)I300Dropped objects (58)I400Fires (58)I500Explosions (58)I600Unintended flooding (58)J.Miscellaneous requirements (59)J100General (59)J200Pre-load capasity (59)J300Overturning stability (59)J400Air gap (59)Sec. 13Special Considerations forTension Leg Platforms (TLP) (61)A.General (61)A100Scope and application (61)A200Description of tendon system (61)B.Structural Categorisation, Material Selection and InspectionPrinciples (62)B100General (62)B200Structural categorisation (62)B300Material selection (63)B400Design temperatures (63)B500Inspection categories (63)C.Design Principles (63)C100General (63)C200Design conditions (64)C300Fabrication (64)C400Hull and Deck Mating (64)C500Sea transportation (64)C600Installation (64)C700Decommissioning (64)C800Design principles, tendons (64)D.Design Loads (65)D100General (65)D200Load categories (65)E.Global Performance (65)E100General (65)E200Frequency domain analysis (66)E300High frequency analyses (66)E400Wave frequency analyses (66)E500Low frequency analyses (66)E600Time domain analyses (66)E700Model testing (67)E800Load effects in the tendons (67)F.Structural Strength (67)F100General (67)F200Hull (68)F300Structural analysis (68)F400Structural design.............................................................68F500Deck.. (68)F600Extreme tendon tensions (69)F700Structural design of tendons (69)F800Foundations (69)G.Fatigue (69)G100General (69)G200Hull and deck (69)G300Tendons (69)G400Foundation (70)H.Accidental Condition (70)H100Hull (70)H200Hull and deck (71)H300Tendons (71)H400Foundations (71)Sec. 14Special Considerations for Deep DraughtFloaters (DDF) (72)A.General (72)A100Introduction (72)A200Scope and application (72)B.Non-Operational Phases (72)B100General (72)B200Fabrication (72)B300Mating (72)B400Sea transportation (72)B500Installation (72)B600Decommissioning (73)C.Structural Categorisation, Selection of Material andExtent of Inspection (73)C100General (73)C200Material selection (73)C300Design temperatures (73)C400Inspection categories (73)C500Guidance to minimum requirements (73)D.Design Loads (74)D100Permanent loads (74)D200Variable functional loads (74)D300Environmental loads (74)D400Determination of loads (74)D500Hydrodynamic loads (74)E.Deformation Loads (74)E100General (74)F.Accidental Loads (75)F100General (75)G.Fatigue Loads (75)G100General (75)bination of Loads (75)H100General (75)I.Load Effect Analysis in Operational Phase (75)I100General (75)I200Global bending effects (75)J.Load Effect Analysis in Non-Operational Phases (75)J100General (75)J200Transportation (76)J300Launching (76)J400Upending (76)J500Deck mating (76)J600Riser installations (76)K.Structural Strength (76)K100Operation phase for hull (76)K200Non-operational phases for hull (76)K300Operation phase for deck or topside (77)K400Non-operational phases for deck or topside (77)L.Fatigue (77)L100General (77)L200Operation phase for hull (77)L300Non-operational phases for hull (77)D ET N ORSKE V ERITASOffshore Standard DNV-OS-C201, April 2005Amended April 2006, Page 8 – Contents see note on front coverL400Splash zone (77)L500Operation phase for deck or topside (78)L600Non-operational phases for deck or topside (78)M.Accidental Condition (78)M100General (78)M200Fire (78)M300Explosion (78)M400Collision (78)M500Dropped objects (78)M600Unintended flooding (78)M700Abnormal wave events (78)App. A Cross Sectional Types (80)A.Cross Sectional Types (80)A100General (80)A200Cross section requirements for plastic analysis (80)A300Cross section requirements whenelastic global analysis is used (80)App. B Methods and Models for Design of Column-Stabilised Units (82)A.Methods and Models (82)A100General (82)A200World wide operation (82)A300Benign waters or restricted areas (82)App. C Permanently Installed Units (83)A.Introduction (83)A100Application (83)B.Inspection and Maintenance (83)B100Facilities for inspection on location................................83C.Fatigue. (83)C100Design fatigue factors (83)C200Splash zone for floating units (83)App. D Certification of Tendon System (84)A.General (84)A100Introduction (84)B.Equipment categorization (84)B100General (84)C.Fabrication Record (84)C100General (84)D.Documentation Deliverables for Certification ofEquipment (85)D100General (85)E.Tendon Systems and Components (85)E100General (85)E200Tendon pipe (85)E300Bottom tendon interface (BTI) (86)E400Flex bearings (86)E500Foundations (86)E600Top tendon interface (TTI) (86)E700Intermediate tendon connectors (ITC) (86)E800Tendon tension monitoring system (TTMS) (86)E900Tendon porch (87)E1000Tendon corrosion protection system (87)E1100Load management program (LMP) (87)F.Categorisation of Tendon Components (87)F100General (87)G.Tendon Fabrication (88)G100General (88)D ET N ORSKE V ERITASAmended April 2006,Offshore Standard DNV-OS-C201, April 2005 see note on front cover Sec.1 – Page 9SECTION 1INTRODUCTIONA. GeneralA 100Introduction101 This offshore standard provides principles, technical re-quirements and guidance for the structural design of offshore structures, based on the Working Stress Design (WSD) meth-od.102 This standard has been written for general world-wide application. Statutory regulations may include requirements in excess of the provisions by this standard depending on size, type, location and intended service of the offshore unit or in-stallation.103 The standard is organised with general sections contain-ing common requirements and sections containing specific re-quirement for different type of offshore units. In case of deviating requirements between general sections and the ob-ject specific sections, requirements of the object specific sec-tions shall apply.A 200Objectives201 The objectives of this standard are to:—provide an internationally acceptable level of safety by de-fining minimum requirements for structures and structural components (in combination with referred standards, rec-ommended practices, guidelines, etc.)—serve as a contractual reference document between suppli-ers and purchasers—serve as a guideline for designers, suppliers, purchasers and regulators—specify procedures and requirements for offshore struc-tures subject to DNV certification and classification.A 300Scope and application301 This standard is applicable to the following types of off-shore structures:—column-stabilised units—self-elevating units—tension leg platforms—deep draught floaters.302 For utilisation of other materials, the general design principles given in this standard may be used together with rel-evant standards, codes or specifications covering the require-ments to materials design and fabrication.303 The standard is applicable to structural design of com-plete units including substructures, topside structures and ves-sel hulls.304 This standard gives requirements for the following: —design principles—structural categorisation—material selection and inspection principles—loads and load effect analyses—design of steel structures and connections—special considerations for different types of units. Requirements for foundation design are given in DNV-OS-C101.A 400Other than DNV codes401 Other recognised codes or standards may be applied pro-vided it is shown that the codes and standards, and their appli-cation, meet or exceed the level of safety of the actual DNV standard.402 In case of conflict between requirements of this standard and a reference document other than DNV documents, the re-quirements of this standard shall prevail.403 Where reference is made to codes other than DNV doc-uments, the latest revision of the documents shall be applied, unless otherwise specified.404 When code checks are performed according to other than DNV codes, the usage factors as given in the respective code shall be used.A 500Classification501 Classification principles, procedures and applicable class notations related to classification services of offshore units are specified in the DNV Offshore Service Specifications given in Table A1.502 Documentation requirements for classification are given by DNV-RP-A202.B. ReferencesB 100General101 The DNV documents in Table B1 are referred to in the present standards and contain acceptable methods for fulfilling the requirements in this standard.102 The latest valid revision of the DNV reference docu-ments in Table B2 applies. See also current DNV List of Pub-lications.103 The documents listed in Table B2 are referred in the present standard. The documents include acceptable methods for fulfilling the requirements in the present standard and may be used as a source of supplementary information. Only the referenced parts of the documents apply for fulfilment of the present standard.Table A1 DNV Offshore Service SpecificationsReference TitleDNV-OSS-101Rules for Classification of Offshore Drilling andSupport UnitsDNV-OSS-102Rules for Classification of Floating Productionand Storage UnitsDNV-OSS-103Rules for Classification of LNG/LPG FloatingProduction and Storage Units or Installations DNV-OSS-121Classification Based on Performance CriteriaDetermined by Risk Assessment MethodologyRules for Planning and Execution of MarineOperationsTable B1 DNV Reference DocumentsReference TitleDNV-OS-A101Safety Principles andArrangementDNV-OS-B101Metallic MaterialsDNV-OS-C101Design of Offshore Steel Struc-tures, General (LRFD method) DNV-OS-C301Stability and Watertight Integrity DNV-OS-C401Fabrication and Testing ofOffshore StructuresD ET N ORSKE V ERITASOffshore Standard DNV-OS-C201, April 2005Amended April 2006, Page 10 – Sec.1see note on front coverC. DefinitionsC 100Verbal forms101 Shall: Indicates a mandatory requirement to be followed for fulfilment or compliance with the present standard. Devia-tions are not permitted unless formally and rigorously justified, and accepted by all relevant contracting parties.102 Should: Indicates a recommendation that a certain course of action is preferred or particularly suitable. Alterna-tive courses of action are allowable under the standard where agreed between contracting parties but shall be justified and documented.103 May: Indicates a permission, or an option, which is per-mitted as part of conformance with the standard.C 200Terms201 Accidental condition: When the unit is subjected to ac-cidental loads such as collision, dropped objects, fire explo-sion, etc.202 Accidental loads: Loads which may occur as a result of accident or exceptional events, e.g. collisions, explosions, dropped objects.203 Atmospheric zone: The external surfaces of the unit above the splash zone.204 Cathodic protection: A technique to prevent corrosion of a steel surface by making the surface to be the cathode of an electrochemical cell.205 Characteristic load: The reference value of a load to be used in the determination of load effects. The characteristic load is normally based upon a defined fractile in the upper end of the distribution function for load.206 Characteristic strength: The reference value of structur-al strength to be used in the determination of the design strength. The characteristic strength is normally based upon a 5% fractile in the lower end of the distribution function for re-sistance.207 Characteristic value: The representative value associat-ed with a prescribed probability of not being unfavourably ex-ceeded during the applicable reference period.208 Classic spar: Shell type hull structure.209 Classification Note: The Classification Notes cover proven technology and solutions which is found to represent good practice by DNV, and which represent one alternative for satisfying the requirements given in the DNV Rules or other codes and standards cited by DNV. The Classification Notes will in the same manner be applicable for fulfilling the require-ments in the DNV Offshore Standards.210 Coating: Metallic, inorganic or organic material applied to steel surfaces for prevention of corrosion.211 Column-stabilised unit: A floating unit that can be relo-cated. A column-stabilised unit normally consists of a deck structure with a number of widely spaced, large diameter, sup-porting columns that are attached to submerged pontoons. 212 Corrosion allowance: Extra wall thickness added during design to compensate for any anticipated reduction in thick-ness during the operation.213 Damaged condition: The unit condition after accidental damage.214 Deep draught floater (DDF): A floating unit categorised with a relative large draught. The large draught is mainly intro-duced to obtain reduced wave excitation in heave and suffi-ciently high eigenperiod in heave such that resonant responses in heave can be omitted or minimised.215 Design brief: An agreed document presenting owner's technical basis, requirements and references for the unit design and fabrication.216 Design temperature: The design temperature for a unit is the reference temperature for assessing areas where the unit can be transported, installed and operated. The design temper-ature is to be lower or equal to the lowest mean daily tempera-ture in air for the relevant areas. For seasonal restricted operations the lowest mean daily temperature in air for the sea-son may be applied.217 Driving voltage: The difference between closed circuit anode potential and the protection potential.218 Dry transit: A transit where the unit is transported on a heavy lift unit from one geographical location to another. 219 Dynamic upending: A process where seawater is filled or flooded into the bottom section of a horizontally floating DDF hull and creating a trim condition and subsequent water filling of hull or moonpool and dynamic upending to bring the hull in vertical position.220 Environmental loads: Loads directly and indirectly due to environmental phenomena. Environmental loads are not a necessary consequence of the structures existence, use and treatments. All external loads which are responses to environ-mental phenomena are to be regarded as environmental loads, e.g. support reactions, mooring forces, and inertia forces. 221 Expected loads and response history: Expected load and response history for a specified time period, taking into ac-count the number of load cycles and the resulting load levels and response for each cycle.222 Expected value: The most probable value of a load dur-ing a specified time period.223 Fail to safe: A failure shall not lead to new failure, which may lead to total loss of the structure.DNV-OS-D101Marine Machinery Systems andEquipmentDNV-OS-E301Position MooringDNV-OS-F201Dynamic RisersDNV-RP-C103Column Stabilised UnitsDNV-RP-C201Buckling Strength of PlatedStructuresDNV-RP-C202Buckling Strength of Shells DNV-RP-C203Fatigue Strength Analysis ofOffshore Steel Structures Classification Note 30.1Buckling Strength Analysis ofBars and Frames, and SphericalShellsClassification Note 30.4 FoundationsClassification Note 30.5 Environmental Conditions andEnvironmental Loads Classification Note 31.5Strength Analysis of MainStructures of Self-elevating Units Table B2 Other referencesReference TitleAISC-ASD Manual of Steel Construction ASDAPI RP 2A – WSD with supplement 1Planning, Designing and Constructing Fixed Offshore Platforms – Working Stress DesignAPI RP 2T Planning, Designing and Constructing TensionLeg PlatformsBS 7910Guide on methods for assessing the acceptability offlaws in fusion welded structuresNACE TPC Publication No. 3. The role of bacteria in corrosionof oil field equipmentSNAME 5-5A Site Specific Assessment of Mobile Jack-Up UnitsD ET N ORSKE V ERITAS。
建筑风格英文作文英文：Architecture is an art form that has been around for centuries. It is a reflection of the culture, history, and traditions of a particular region. There are many different types of architectural styles that exist around the world, each with its own unique characteristics and features.One of the most popular architectural styles is the Gothic style. This style originated in France in the 12th century and is characterized by its pointed arches, ribbed vaults, and flying buttresses. This style was usedprimarily in the construction of churches and cathedrals, but it has since been used in other types of buildings as well.Another popular architectural style is the Renaissance style. This style originated in Italy in the 15th century and is characterized by its use of classical forms andsymmetry. This style was used primarily in the construction of palaces and public buildings.In addition to these styles, there are many other types of architectural styles that exist around the world. For example, the Art Deco style, which originated in France in the 1920s, is characterized by its use of geometric shapes and bold colors. This style was used primarily in the construction of buildings such as cinemas and hotels.Overall, architecture is a fascinating subject that has a rich history and many different styles. Each style hasits own unique characteristics and features, and they all contribute to the beauty and diversity of the built environment.中文：建筑是一个已经存在了数百年的艺术形式。
有关林徽因建筑成就的作文素材1.林徽因是中国近代著名的建筑师和作家。
Lin Huiyin was a famous modern Chinese architect and writer.2.她在建筑设计领域取得了一系列的成就。
She achieved a series of accomplishments in the field of architectural design.3.她设计的广州圆明园是中国现代建筑的代表作之一。
The Guangzhou Circle Mansion she designed is one of the masterpieces of modern Chinese architecture.4.林徽因还是中国第一位女建筑师。
Lin Huiyin was also the first female architect in China.5.她在建筑设计上独具匠心。
She had unique insights in architectural design.6.她的设计理念受到了很多人的称赞和推崇。
Her design concepts have been praised and admired by many.7.她注重保护文化遗产，倡导融合传统与现代的建筑风格。
She emphasized the protection of cultural heritage and advocated for the integration of traditional and modern architectural styles.8.她的建筑作品充满了东方的特色和文化底蕴。
Her architectural works are full of oriental features and cultural connotations.9.她对中国古建筑有深入的研究和领悟。
Architectural Styles for DistributionUsing macro-patterns for system designCharles Weir© Charles Weir, June 1997AbstractThis paper highlights the problem of describing the software architecture of a distributed system, and introduces the Architectural Styles proposed by Shaw&Garlan as a possible solution. Using a pattern template, it explores four major styles for distribution architecture: Host-Terminal, Client-Server, Broadcast Data and Batch Communication.IntroductionOne major problem we find in building large software systems is the problem of talking about their structure. How do we discuss different ways of putting together system components? Currently we lack a sufficiently rich vocabulary.There is a very effective method to build up a vocabulary. We use narrative, examples, similes and references to build up new concepts in the mind of the reader, and then give this concept a name. From then on we can use the name in our discussions and documentation. I am aware of two leading researchers using this kind of approach: [Jackson] describes ‘Problem Frames’ (structures for a system), and uses a narrative approach to describe them and the architectural issues surrounding them. [Shaw&Garlan] describe ‘Architectural Styles’, using approach similar to that of the pattern movement. This paper extends the work of [Shaw&Garlan] to explore styles for the architecture of distributed systems.Shaw&Garlan’s Architectural Styles[Shaw&Garlan] distils the essence of large system design using an approach very similar to the software patterns first promoted by Richard Gabriel and derived from the work of Christopher Alexander. As with a pattern, each architectural style has a simple short descriptive name. However the authors do not use a template for their styles. Instead a narrative description attempts to cover the following items:Table 1: Elements of a Shaw&Garlan Architectural StyleUsing StylesThe book [Shaw&Garlan] goes on to stress that in practice any given system will use a combination of styles, rather than exclusively one. In this respect, architectural styles appear very similar to software patterns ([Gamma+]).I myself have used styles to discuss the overall software architecture for two new software projects. I find, as with patterns, the names and the rules of behaviour implied by each style helps considerably when sketching out options for the high-level design of a system.However the descriptions in [Shaw&Garlan] are limited. Their narrative approach leads to some being explained well; others sketched only in the vaguest detail. My experiments with describing styles in this informal way (see [Weir]) have led me to conclude that a more structured approach, based on the pattern format, is more profitable. This paper uses such a pattern structure to describe several styles commonly used in distribution architectures.Architectural styles differ significantly in content from many of the other types of software pattern, so this paper uses a rather different pattern template. The template preserves the elements of theShaw&Garlan styles (see Table 1) as follows:Table 2: The pattern format used in the descriptions.I’ve found in practice that perhaps the most important of these is the discussion of the invariants of each style. These provide rules for developers implementing the architectures; we know that we are keeping to a specific architectural style if we haven’t broken its invariants.Styles for Distribution ArchitectureThis paper introduces four commonly used styles,1. The Host-Terminal Style2. The Client-Server Style3. The Broadcast Data Style4. The Batch Communication StyleThe following sections describe these in detail.The Host-Terminal StyleThe ProblemIn very many systems we have a number of users or data entry points which are geographically distributed, but which share common resources such as a database. In many systems there has been much less computing power needed or available in the distributed systems than in the central system. The SolutionIn the mainframe-terminal style we leverage the limited processing available in the distributed components by making them run a single, fixed, program: the terminal. This terminal can then be optimised to make the best possible use of the limited resources in each component. The terminal supports a single terminal protocol, and has a single logical connection directly to the host, which is shared between all of the terminals.Thus the components are: the terminals and the host. The connectors are: the terminal protocols.Figure 1: The Host-Terminal StyleTypically a terminal will not have facilities dedicated to any specific application. Instead typical examples of facilities supported by terminals are:• Rendering text at an arbitrary point on the screen• Rendering graphics on the screen• Rendering and supporting GUI components, such as buttons or menus, on the screen.• Sending user keystrokes, menu selections, and pointer events to the host• Creating ‘forms’ according to a template. These allow the terminal to ‘batch’ up user input locally for more efficient processing by the host.• Support printer output sent from the host to a printer connected to the terminal.InvariantsThe terminal communicates only with the host.The terminal runs a single software program, which may interface to one or many different programs on the host.The terminal software is controlled completely by the host program.ApplicabilityThis style is suitable for applications supporting multiple users, which can run on a single host.All the significant application processing takes place in the host. This means that we need not take communication delays and problems into consideration when designing the application software. However the host-terminal style is effective only when:1. There is a continuous real-time link between terminal and host.2. Either the user interface is relatively simple, or the bandwidth of the link is large and the host hasplenty of processing power to devote to each user interface.The cost of providing both of the above can be considerable, particular given the needs of modern users for easy-to-learn, and therefore intelligent and graphical, user interfaces.ExamplesThe Host-terminal style has its roots in the earliest forms of shared computer system. Even today this style is probably the most common form of distributed processing. Often the terminals involved nowadays themselves will be PCs, capable of much more powerful processing in their own right. However the terminal protocols (and terminal emulator software) remain in many cases the only practical way to communicate with mainframe systems.The DEC VT100 Terminal. This character-based terminal displays characters on the screen and passes user keystrokes back to the host. The simplicity of the protocol model has made it a popular approach for mini-computers, and there are many variants of this protocol.The IBM 370 terminal. These character-based terminals use forms to reduce the load on the host and the communication bandwidth required. This makes them more suitable than the VT100 terminals for mainframes supporting large numbers of terminals.VariationsThe X Terminal extends the terminal concept to support a graphical user interface via a local area network (LAN) or Wide Area Network (WAN). It supports communication with multiple simultaneous hosts. In fact, an X Terminal uses the ‘Client-Server Architectural Style’ (see below) to share its resources between these multiple hosts. It acts as a server supplying screen and keyboard interface resources that are shared between many client applications, who use RPC protocols to interface to the server.For form-based data entry, it is frequently not necessary for the user to receive acknowledgement that the form has been processed before continuing. So some form-based terminals support intermediate‘batching systems’ between the terminal and the host. These take the data entry from many terminals and batch it into single large messages for efficient processing by the mainframes, while still ensuring data integrity. These batching systems appear as hosts to the terminals.The Client-Server StyleThe ProblemOften we have situations where much of the processing can be local to specific machines, and yet we need some co-ordination between them. For example, modern PCs can provide significant local graphical user interface support, and some simple data validation. Yet if the users are to interact with any kind of enterprise-wide or global data set, they will need access to shared resources. And these shared resources will need to be managed carefully to avoid conflicts as more than one system attempts to access them.The SolutionThe client-server style provides a solution. In a client-server style the components involved are Clients and Servers. They communicate via a logical connection that lasts the duration of the interaction. Each client makes requests to a server, which generates responses back.The clients and servers are roles; a given component may take the role both of client and server. These components may be variously:• Processes• Objects, or• Hardware devicesInvariantsA component has no accessible state other than that revealed by its client interface.The server has no a-priori knowledge of any given client. It is the responsibility of each client to locate and ‘register with’ the server.Clients have no communication between themselves, other than via the server. Although a client of one server may itself be a server to other clients.ApplicabilityThe client-server model is suitable for architectures where:1. Both clients and server command significant processing power.2. There is a clear separation between the roles of the client and the server. And each interaction isdriven by a requester, the client, and a supplier, the server.3. There is not too much shared data between the client and the server. To much data or too complexan interface will make the communication between them unwieldy.4. The server has no need for a-priori knowledge of its clients.A widely-used mechanism for client-server interactions is Remote Procedure Calls (RPC).The chief benefit of the style is that the underlying model is easy to understand. An RPC implementation maps intuitively onto the call-and-return semantics of most common programming languages. Similarly the object broker standards extend these semantics to match object-oriented languages.However there can be a significant penalty in client complexity and performance. The complexity occurs because both client and server must be designed with distribution in mind; the interface between them is subject to significant restrictions, particularly that each call takes a significant time.The performance penalty occurs because of the time for the network round-trip and the task switch times involved. In particular, processing at the client must wait for the return of the procedure. To get around this, some client-server interfaces allow functions that return no data to return immediately, without waiting for the server message round-trip. Where the server reply is required, the client must implement all the complexities of multi-threading in order to provide a response to other stimuli while waiting for a server reply.Also the thread aspects can become complicated: typically a client thread will need to block until it receives a response. In other words, the thread effectively spans two components, the client and the server. If the server is itself a client of further servers, this thread may continue in further components, perhaps even back to the original client. This sometimes requires a multi-threaded environment in the client, the server, or frequently both.Some client interfaces (such as Sun’s NFS protocols) are state-less; the server behaves as though it has no retained information about any client between each RPC. More commonly, client interfaces are session-based; the server retains information of the client’s session.A stateless model is more difficult to design and implement. However it can make it much easier to optimise the performance of the server, since there is no requirement to preserve data locks between client calls. Since data locks can become the main bottleneck in large-scale systems, this improvement is significant. [Waldo+] provides a further discussion of the problems of state-based distribution.ExamplesThe CORBA standard and the Microsoft COM system (see [Orfali+]) are both based on a client-server model. Here the components are objects that may be distributed over a network.The DCE standard uses a client-server model to provide interprocess communication across a network.Forte and Dynasty are development environments using the client-server model. They both allow developers to produce code on a system with no distribution, then add the distribution as part of the deployment of the finished system.Many common distribution mechanisms are based on the client-server model. For example:Databases Distributed databases such as Sybase and Oracle use client-server processes. The server processes manage the database; client processes contain the user code. A typical RPC callcontains a series of SQL instructions.File Server Distributed file server protocols, such as Sun’s NFS or Novel’s NetWare, use the client-server model.GUI The X Window system uses a client-server approach. Here the server renders the images on the screen; the clients are the X applications.Many of the Internet client protocols (Telnet, FTP and HTTP, for example) use a client-server model. HTTP, in particular, uses a stateless model, which partially explains the success of the World Wide Web. The phenomenal performance of such servers as the Web Search engines can occur only because they have no need to preserve client state.VariationsIn some environments the client-server model is extended to support more than one response to a single request. For example, the client may register with the server, and subsequently receive data broadcast from the server. Or the client may make calls that require no return value, and may therefore be sent and processed asynchronously. Or else the client may provide its own identity and an interface to the server as part of the registration, allowing the server to make call-backs to the client when necessary. The client-server style is also common in situations where there is no physical distribution at all, but where client and server are merely in separate processes. In this case, the style provides a ‘firewall’between the client code and the server code. Microsoft’s OCX components use a client-server model, but have only recently started to support physical distribution. Similarly a vast majority of the systems using IBM/Apple OpenDoc environment have client and server physically co-located, even though the CORBA protocol allows them not to be.The Broadcast Data StyleThe ProblemSometimes we need to distribute information to many points, where only the receivers, not the senders, need to ensure the integrity of the data. This situation is common in news and real-time financial trading systems.The SolutionIn the Broadcast Data Style, a server broadcasts messages that may be received by multiple receivers. The messages conform to a protocol that allows the receivers to detect any missing messages.So the components are:Servers and receivers.The connectors are: A broadcast stream of messages.Figure 3: The Broadcast Data StyleIn most LANs and WANs, the receivers must first set up the broadcast channel, by notifying the server which data streams they wish to receive. A common approach is to use the Client-Server style (see page 4).The Broadcast data style is the distributed analogue of ‘Event System’ style in [Shaw&Garlan]. The broadcast messages correspond to events in the Event System style.InvariantsThe broadcast stream is one-way, from the server to any number of receivers.The server has no interest in whether any specific receiver has received a particular message. It is the sole responsibility of the receivers to ensure their data integrity. The protocol must include mechanisms to allow this.ApplicabilityThe broadcast data style is suitable for systems where one process is aware of events that must be communicated to a number of others.Usually the broadcast protocol will include a mechanism for the receivers to re-retrieve lost data. This may be by a direct interaction with the server (usually using the Client-Server mechanism), or with a periodic re-broadcast of the data by the server.The style is obviously well suited to exploiting hardware broadcast mechanisms such as satellite broadcast, LAN broadcast, and LAN multicast protocols. However it may also be appropriate in situations where there is a two-way link, such as a network connection or a serial line, between the server and every receiver. The benefit of the style in this case is that the protocol makes few demands on the server; in most cases the server need not manage separate connections to each receiver but can treat its output mechanism as a simple pipe.ExamplesReuters International Data Network (IDN) provides the world-wide dissemination of real-time financial data. Many of the protocols used conform to the Broadcast Data style. In particular, the satellite links, both between major financial centres and from the data centres to client terminals, use broadcast mechanisms with no communication at all from the receiver to the server. IDN also includes LAN-based protocols such as the Triarch’s RRCP, where the receiver does request specific broadcast streams and can re-request missed messages.Another financial distribution mechanism, the Teknekron TIB bus, also uses a LAN-based protocol where the receiver makes requests and can re-request lost data.The Internet Usenet protocols use broadcast mechanisms, where the receiver can request specific broadcast streams.The Prestel system uses television signals to broadcast text data to special receivers associated with the television.There are several extensions to the Internet HTTP protocol and the CORBA ORB protocols to allow broadcast distribution of information over the Internet. An example is the proprietary ‘pointcast’protocol for distributing web pages.The Batch Communication StyleThe ProblemThe previous three styles all rely on a continuous electronic link between all of the distributed systems. However in many cases such a link may not exist, or may not provide sufficient bandwidth to allow anything approach a real-time connection for all of the applications that need to communicate.The SolutionIn the Batch communication style one component creates messages that are processed another at a later time. We call the first component the sender and the second the receiver. Between the two, there is a store and forward protocol, which ensures the eventual delivery of data between the two.Figure 4: The Batch Communication StyleInvariantsThe sender system assumes that the data will be delivered. The infrastructure takes responsibility of handling delivery problems, time-outs and lost messages; these are not the responsibility of the sender. The system preserves some kind of ordering of messages between a specific sender and receiver -although this need not necessarily be a strict sequence. If the sequencing is not strict, it is up to the sender to indicate which data must be sequenced.ApplicabilityThis style is appropriate for any distribution architecture where the sender process does not need direct confirmation of any actions taken by the receiver process.It is commonly used where real-time communication is expensive or impossible.It is also usually much simpler to implement than a real-time connection between two systems and therefore has smaller development costs.There are many different possible delivery mechanisms underlying the protocol, for example:• Transaction-based store and forward mechanisms such as IBM’s MQ system. These guarantee delivery or notify a human operator of the problem.• Lightweight store and forward mechanisms, such as the Email protocols or the Usenet NNTP protocol.• Writing to file store and transferring the resulting file, either electronically via protocols such as FTP, or physically as tape, disk, or CD.The different mechanisms have different performance, cost and speed attributes.ExamplesThe ‘batch processing’ idiom common to mainframe systems uses this style. Typically in batch processing, of course, the sender and receiver are separate in time, rather than geographically distributed; however geographic distribution (often implemented by carrying tapes around) is also common.A more recent invention, ‘Message-Oriented-Middleware’, implements a similar scheme for mainframe-style systems allowing systems to communicate over a network using asynchronous messages whose delivery is guaranteed. Examples include IBM’s MQ system.Both Lotus Notes and the Usenet Network News Transfer Protocol (NNTP) use batch communication to implement a batch update from one server to another (known as ‘replication’). Each server acts as both sender and receiver (although not, usually, at the same time); they send new database records they have received from their users and other servers.Most Email systems use the batch communication style. Here the senders and receivers are the creators and readers of the mails; the intermediate protocols are message systems such as the Simple Mail Transfer Protocol (SMTP).The terminal ‘batching systems’ discussed in ‘The Client-Server Style’ use a batch communication style. In this case the senders are the terminals; the receivers are the mainframe’s form processing systems.Other Related StylesThe above are only a few of many possible styles for distribution architecture. Some alternatives are:• Peer-to-peer communication. Many host systems send one another messages as peers.This style is suitable where the system must continue functioning even when a single component is missing or broken. For example the TCP Internet protocol (and other modern network bridge systems) is based on peer-to-peer communication between network routers who are all equal.• Inter-process communication. Within a single system, applications may perform inter-process communication using shared memory and semaphores.This style is suitable where very fast communication is required between the processes on a single host.• Shared database systems. The distributed systems use client-server facilities provided by their database vendor. From the point of view of the application designer, the approach is the Database style of [Shaw&Garlan].This style is suitable for applications that need data consistency between the different components.Examples include airline reservation or sales entry systems.References[Coplien&Schmidt]Pattern Languages of Programming, Coplien and Schmidt, Addison-Wesley,ISBN 0-201-60734-4[Gamma+]Design Patterns, Gamma, Helm, Johnson and Vlissides, Addison-Wesley, ISBN 0-201-63361-2[Jackson]Software Requirements and Specifications, Michael Jackson, Addison-Wesley, ISBN 0-201-87712-0[Orfali+]Essential Distributed Objects Survival Guide, Orfali, Harkey and Edwards, John Wiley and Sons Ltd., ISBN 0-471-12993-3[Shaw&Garlan]Software Architecture - Perspectives on a Emerging Discipline, Shaw and Garlan, Prentice Hall ISBN 0-13-182957-2[Waldo+] A Note on Distributed Computing, Waldo, Wyant, Wollrath and Kendall, Sun Microsystems Laboratories, /smli/technical-reports/1994/smli_tr-94-29.ps[Weir] A Client-Server Architectural Style, Charles Weir, Submission to Working Group at Object Technology 97. /~cweir/ot97wg/papers/cli-ser.ps。
