DOCSLIB.ORG

Design Optimization of Solid Rocket Motor Grains for Internal Ballistic Performance

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Design Optimization of Solid Rocket Motor Grains for Internal Ballistic Performance University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2006 Design Optimization Of Solid Rocket Motor Grains For Internal Ballistic Performance Roger Hainline University of Central Florida Part of the Mechanical Engineering Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Masters Thesis (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Hainline, Roger, "Design Optimization Of Solid Rocket Motor Grains For Internal Ballistic Performance" (2006). Electronic Theses and Dissertations, 2004-2019. 934. https://stars.library.ucf.edu/etd/934 DESIGN OPTIMIZATION OF SOLID ROCKET MOTOR GRAINS FOR INTERNAL BALLISTIC PERFORMANCE by R. CLAY HAINLINE B.S. Southwest Missouri State University, 1998 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the Department of Mechanical, Materials, and Aerospace Engineering in the College of Engineering and Computer Science at the University of Central Florida Orlando, Florida Summer Term 2006 © 2006 R. Clay Hainline ii ABSTRACT The work presented in this thesis deals with the application of optimization tools to the design of solid rocket motor grains per internal ballistic requirements. Research concentrated on the development of an optimization strategy capable of efficiently and consistently optimizing virtually an unlimited range of radial burning solid rocket motor grain geometries. Optimization tools were applied to the design process of solid rocket motor grains through an optimization framework developed to interface optimization tools with the solid rocket motor design system. This was done within a programming architecture common to the grain design system, AML. This commonality in conjunction with the object-oriented dependency-tracking features of this programming architecture were used to reduce the computational time of the design optimization process. The optimization strategy developed for optimizing solid rocket motor grain geometries was called the internal ballistic optimization strategy. This strategy consists of a three stage optimization process; approximation, global optimization, and high- fidelity optimization, and optimization methodologies employed include DOE, genetic algorithms, and the BFGS first-order gradient-based algorithm. This strategy was successfully applied to the design of three solid rocket motor grains of varying complexity. The contributions of this work are the application of an optimization strategy to the design process of solid rocket motor grains per internal ballistic requirements. iii This work is dedicated to my wife, Sachie, my parents, Roger and Nancy, and parents-in- law, Katsuhide and Chieno. Thank you for your support during the time it took to complete this thesis. iv ACKNOWLEDGMENTS I would like to express sincere appreciation to my advisors, Jamal F. Nayfeh, Ph.D.; Alain Kassab, Ph.D.; and P. Richard Zarda, Ph.D. for their support and advise during my time as a graduate student. Special thanks are extended to Carlos G. Ruiz and Dean T. Kowal for technical advise and support shared while working on this research. Gratitude is extended to Lockheed Martin, Missiles and Fire Control; Vanderplaats Research and Development Inc.; and TechnoSoft Inc. for supplying me the necessary software and licensing to successfully complete this research. The support received by the staff of the aforementioned companies was greatly appreciated. v TABLE OF CONTENTS LIST OF FIGURES ...................................................................................... IX LIST OF TABLES........................................................................................ XI LIST OF TABLES........................................................................................ XI CHAPTER 1: INTRODUCTION.................................................................1 1-1 Introduction ................................................................................................................ 1 1-2 Scope of Work ............................................................................................................ 3 1-3 Software Application and Integration......................................................................... 4 1-4 Research Contributions............................................................................................... 6 CHAPTER 2: TECHNICAL SUMMARY...................................................8 2-1 Principles of Optimization.......................................................................................... 8 2-1-1 Objective Function ................................................................................................ 9 2-1-2 Design Variables ................................................................................................. 10 2-1-3 Constraints........................................................................................................... 11 2-2 Objective Function: Damped Least Squared Method............................................... 12 2-3 Solid Rocket Motor Grains....................................................................................... 13 2-3-1 Principle Components of a Solid Rocket Motor Grain ....................................... 14 2-3-2 Solid Propellant Grain Geometry........................................................................ 16 2-3-3 Burn Process of a Solid Rocket Motor Grains .................................................... 17 2-3-4 Nozzle Geometry................................................................................................. 19 2-3-5 Thrust Calculations.............................................................................................. 20 2-4 Approximation Techniques ...................................................................................... 22 2-4-1 Design of Experiments (DOE) ............................................................................ 22 2-4-2 Response Surface Methodology.......................................................................... 24 2-5 Optimization Algorithms.......................................................................................... 25 2-5-1 First-order Gradient Based Methods ................................................................... 25 2-5-2 Second-order Gradient Based Methods............................................................... 26 2-5-3 Genetic Optimization Methods ........................................................................... 28 CHAPTER 3: THRUST OPTIMIZATION FRAMEWORK AND IMD ..31 3-1 Adaptive Modeling Language .................................................................................. 31 3-1-1 Object-Oriented Programming Language ........................................................... 32 3-1-2 Demand-Driven Dependency Tracking Language.............................................. 34 vi 3-1-3 Solid Rocket Motor Design Module ................................................................... 36 3-2 Optimization Interface.............................................................................................. 37 CHAPTER 4: OPTIMIZATION PROBLEM STATEMENT ...................41 4-1 Optimization Problem Statement.............................................................................. 41 4-2 Design Variables....................................................................................................... 43 4-3 Design Constraints.................................................................................................... 44 4-4 Design Objective ...................................................................................................... 45 CHAPTER 5: OPTIMIZATION FORMULATION AND STRATEGY ..46 5-1 The Internal Ballistic Optimization Strategy............................................................ 46 5-1-1 Internal Ballistic Optimization Strategy Overview............................................. 46 5-1-2 Internal Ballistic Optimization Strategy Stage 1: Design Approximation .......... 48 5-1-3 Internal Ballistic Optimization Strategy Stage 2: Design Optimization ............. 49 5-1-4 Internal Ballistic Optimization Strategy Stage 3: High-Fidelity Optimization... 52 5-2 Optimization Formulation ........................................................................................ 54 5-2-1 Thrust Optimization Formulation........................................................................ 55 5-2-2 Burn-Area Optimization...................................................................................... 56 5-3 Resolved Issues with the Optimization Strategy ...................................................... 57 5-3-1 Issue 1: Error in Surface Recession Model ......................................................... 57 5-3-2 Issue 2: Unexpected Halting of High Fidelity Optimization............................... 58 CHAPTER 6: OPTIMIZATION ANALYSIS ...........................................59 6-1 Internal Ballistic Optimization Strategy Trial #1 ..................................................... 59 6-1-1 Optimization Model Definition........................................................................... 61 6-1-2 Internal Ballistic Optimization Strategy Stage 1: Design Approximation .........
Load more

Recommended publications
  • University of Montana Report of the President 1927-1928 University of Montana (Missoula, Mont.)
    University of Montana ScholarWorks at University of Montana University of Montana Report of the President, University of Montana Publications 1895-1968 1-1-1928 University of Montana Report of the President 1927-1928 University of Montana (Missoula, Mont.). Office of ther P esident Let us know how access to this document benefits ouy . Follow this and additional works at: https://scholarworks.umt.edu/presidentsreports_asc Recommended Citation University of Montana (Missoula, Mont.). Office of the President, "University of Montana Report of the President 1927-1928" (1928). University of Montana Report of the President, 1895-1968. 33. https://scholarworks.umt.edu/presidentsreports_asc/33 This Report is brought to you for free and open access by the University of Montana Publications at ScholarWorks at University of Montana. It has been accepted for inclusion in University of Montana Report of the President, 1895-1968 by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. t O f f III STATE UNIVERSITY of MONTANA * * * PRESIDENT’ S ANNUAL REPORT 1927 - 1928 ********* ******* ***** * * * * TABLE OF CONTENTS FOR PRESIDENT’ S RE -ORT 1927-1928 A. President’ s Report ------------------------------------------------------------------------------ Page 1 B . Reports of Administrative Officers I. Dean of the Faculty ----------------------------------------------------------------------- " 9 I I. (a) Dean of Men (Not Reported) (b) Dean of Yvomen — " 10 III.(a) Registrar
    [Show full text]
  • L AUNCH SYSTEMS Databk7 Collected.Book Page 18 Monday, September 14, 2009 2:53 PM Databk7 Collected.Book Page 19 Monday, September 14, 2009 2:53 PM
    databk7_collected.book Page 17 Monday, September 14, 2009 2:53 PM CHAPTER TWO L AUNCH SYSTEMS databk7_collected.book Page 18 Monday, September 14, 2009 2:53 PM databk7_collected.book Page 19 Monday, September 14, 2009 2:53 PM CHAPTER TWO L AUNCH SYSTEMS Introduction Launch systems provide access to space, necessary for the majority of NASA’s activities. During the decade from 1989–1998, NASA used two types of launch systems, one consisting of several families of expendable launch vehicles (ELV) and the second consisting of the world’s only partially reusable launch system—the Space Shuttle. A significant challenge NASA faced during the decade was the development of technologies needed to design and implement a new reusable launch system that would prove less expensive than the Shuttle. Although some attempts seemed promising, none succeeded. This chapter addresses most subjects relating to access to space and space transportation. It discusses and describes ELVs, the Space Shuttle in its launch vehicle function, and NASA’s attempts to develop new launch systems. Tables relating to each launch vehicle’s characteristics are included. The other functions of the Space Shuttle—as a scientific laboratory, staging area for repair missions, and a prime element of the Space Station program—are discussed in the next chapter, Human Spaceflight. This chapter also provides a brief review of launch systems in the past decade, an overview of policy relating to launch systems, a summary of the management of NASA’s launch systems programs, and tables of funding data. The Last Decade Reviewed (1979–1988) From 1979 through 1988, NASA used families of ELVs that had seen service during the previous decade.
    [Show full text]
  • Orion Capsule Launch Abort System Analysis
    Orion Capsule Launch Abort System Analysis Assignment 2 AE 4802 Spring 2016 – Digital Design and Manufacturing Georgia Institute of Technology Authors: Tyler Scogin Michel Lacerda Jordan Marshall Table of Contents 1. Introduction ......................................................................................................................................... 4 1.1 Mission Profile ............................................................................................................................. 7 1.2 Literature Review ........................................................................................................................ 8 2. Conceptual Design ............................................................................................................................. 13 2.1 Design Process ........................................................................................................................... 13 2.2 Vehicle Performance Characteristics ......................................................................................... 15 2.3 Vehicle/Sub-Component Sizing ................................................................................................. 15 3. Vehicle 3D Model in CATIA ................................................................................................................ 22 3.1 3D Modeling Roles and Responsibilities: .................................................................................. 22 3.2 Design Parameters and Relations:............................................................................................
    [Show full text]
  • Materials for Liquid Propulsion Systems
    https://ntrs.nasa.gov/search.jsp?R=20160008869 2019-08-29T17:47:59+00:00Z CHAPTER 12 Materials for Liquid Propulsion Systems John A. Halchak Consultant, Los Angeles, California James L. Cannon NASA Marshall Space Flight Center, Huntsville, Alabama Corey Brown Aerojet-Rocketdyne, West Palm Beach, Florida 12.1 Introduction Earth to orbit launch vehicles are propelled by rocket engines and motors, both liquid and solid. This chapter will discuss liquid engines. The heart of a launch vehicle is its engine. The remainder of the vehicle (with the notable exceptions of the payload and guidance system) is an aero structure to support the propellant tanks which provide the fuel and oxidizer to feed the engine or engines. The basic principle behind a rocket engine is straightforward. The engine is a means to convert potential thermochemical energy of one or more propellants into exhaust jet kinetic energy. Fuel and oxidizer are burned in a combustion chamber where they create hot gases under high pressure. These hot gases are allowed to expand through a nozzle. The molecules of hot gas are first constricted by the throat of the nozzle (de-Laval nozzle) which forces them to accelerate; then as the nozzle flares outwards, they expand and further accelerate. It is the mass of the combustion gases times their velocity, reacting against the walls of the combustion chamber and nozzle, which produce thrust according to Newton’s third law: for every action there is an equal and opposite reaction. [1] Solid rocket motors are cheaper to manufacture and offer good values for their cost.
    [Show full text]
  • Aerospace Facts and Figures 1983/84
    Aerospace Facts and Figures 1983/84 AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. 1725 DeSales Street, N.W., Washington, D.C. 20036 Published by Aviation Week & Space Technology A MCGRAW-HILL PUBLICATION 1221 Avenue of the Americas New York, N.Y. 10020 (212) 997-3289 $9.95 Per Copy Copyright, July 1983 by Aerospace Industries Association o' \merica, Inc. · Library of Congress Catalog No. 46-25007 2 Compiled by Economic Data Service Aerospace Research Center Aerospace Industries Association of America, Inc. 1725 DeSales Street, N.W., Washington, D.C. 20036 (202) 429-4600 Director Research Center Virginia C. Lopez Manager Economic Data Service Janet Martinusen Editorial Consultant James J. Haggerty 3 ,- Acknowledgments Air Transport Association of America Battelle Memorial Institute Civil Aeronautics Board Council of Economic Advisers Export-Import Bank of the United States Exxon International Company Federal Trade Commission General Aviation Manufacturers Association International Civil Aviation Organization McGraw-Hill Publications Company National Aer~mautics and Space Administration National Science Foundation Office of Management and Budget U.S. Departments of Commerce (Bureau of the Census, Bureau of Economic Analysis, Bureau of Industrial Economics) Defense (Comptroller; Directorate for Information, Operations and Reports; Army, Navy, Air Force) Labor (Bureau of Labor Statistics) Transportation (Federal Aviation Administration The cover and chapter art throughout this edition of Aerospace Facts and Figures feature computer-inspired graphics-hot an original theme in the contemporary business environment, but one particularly relevant to the aerospace industry, which spawned the large-scale development and application of computers, and conti.nues to incorpora~e computer advances in all aspects of its design and manufacture of aircraft, mis­ siles, and space products.
    [Show full text]
  • NYC Aerospace Rocket Program
    NYC Aerospace Rocket Program NYC Aerospace’s 100,000ft rocket program is committed to designing and manufacturing a sounding rocket to reach 100,000ft, above 99% of the atmosphere. The purpose of this mission is to research the applications of ammonium perchlorate composite propellant (APCP) to large rockets. Many future aerospace engineers have learned a great deal about rocketry from participating in this project, which is one of NYC Aerospace’s many projects involving students citywide. Rocket details Our goal is to send a single-stage rocket to 100,000ft using ammonium perchlorate composite propellant (APCP). In order to reach this altitude, the rocket will likely need to maintain structural integrity at velocities on the order of Mach 2 and above. Therefore, the rocket body will need to be made of a light metal such as aluminum or titanium. A metal body necessitates the capacity of the rocket motor to be in the O range of near 30,000Ns of impulse. Assuming a perfectly efficient motor, this requires around 30lb of propellant. We can calculate fuel fraction by first establishing our delta v budget. Δv = √2gz = √2(9.8m/s2)(30480m) =772m/s= mach 2.25 Using the delta v necessary, we can calculate the minimum fuel fraction using Tsiolkovsky’s ideal rocket equation. Assuming the specific impulse of our motor is 228s: m final Δv =− v eln m initial m final = exp(− 772/2280) = 0.71 m initial Thus, we only need 29% of our rocket to be fuel. This brings the max mass of our rocket to 103lb.
    [Show full text]
  • Interstellar Probe on Space Launch System (Sls)
    INTERSTELLAR PROBE ON SPACE LAUNCH SYSTEM (SLS) David Alan Smith SLS Spacecraft/Payload Integration & Evolution (SPIE) NASA-MSFC December 13, 2019 0497 SLS EVOLVABILITY FOUNDATION FOR A GENERATION OF DEEP SPACE EXPLORATION 322 ft. Up to 313ft. 365 ft. 325 ft. 365 ft. 355 ft. Universal Universal Launch Abort System Stage Adapter 5m Class Stage Adapter Orion 8.4m Fairing 8.4m Fairing Fairing Long (Up to 90’) (up to 63’) Short (Up to 63’) Interim Cryogenic Exploration Exploration Exploration Propulsion Stage Upper Stage Upper Stage Upper Stage Launch Vehicle Interstage Interstage Interstage Stage Adapter Core Stage Core Stage Core Stage Solid Solid Evolved Rocket Rocket Boosters Boosters Boosters RS-25 RS-25 Engines Engines SLS Block 1 SLS Block 1 Cargo SLS Block 1B Crew SLS Block 1B Cargo SLS Block 2 Crew SLS Block 2 Cargo > 26 t (57k lbs) > 26 t (57k lbs) 38–41 t (84k-90k lbs) 41-44 t (90k–97k lbs) > 45 t (99k lbs) > 45 t (99k lbs) Payload to TLI/Moon Launch in the late 2020s and early 2030s 0497 IS THIS ROCKET REAL? 0497 SLS BLOCK 1 CONFIGURATION Launch Abort System (LAS) Utah, Alabama, Florida Orion Stage Adapter, California, Alabama Orion Multi-Purpose Crew Vehicle RL10 Engine Lockheed Martin, 5 Segment Solid Rocket Aerojet Rocketdyne, Louisiana, KSC Florida Booster (2) Interim Cryogenic Northrop Grumman, Propulsion Stage (ICPS) Utah, KSC Boeing/United Launch Alliance, California, Alabama Launch Vehicle Stage Adapter Teledyne Brown Engineering, California, Alabama Core Stage & Avionics Boeing Louisiana, Alabama RS-25 Engine (4)
    [Show full text]
  • Delta IV Parker Solar Probe Mission Booklet
    A United Launch Alliance (ULA) Delta IV Heavy what is the source of high-energy solar particles. MISSION rocket will deliver NASA’s Parker Solar Probe to Parker Solar Probe will make 24 elliptical orbits an interplanetary trajectory to the sun. Liftoff of the sun and use seven flybys of Venus to will occur from Space Launch Complex-37 at shrink the orbit closer to the sun during the Cape Canaveral Air Force Station, Florida. NASA seven-year mission. selected ULA’s Delta IV Heavy for its unique MISSION ability to deliver the necessary energy to begin The probe will fly seven times closer to the the Parker Solar Probe’s journey to the sun. sun than any spacecraft before, a mere 3.9 million miles above the surface which is about 4 OVERVIEW The Parker percent the distance from the sun to the Earth. Solar Probe will At its closest approach, Parker Solar Probe will make repeated reach a top speed of 430,000 miles per hour journeys into the or 120 miles per second, making it the fastest sun’s corona and spacecraft in history. The incredible velocity trace the flow of is necessary so that the spacecraft does not energy to answer fall into the sun during the close approaches. fundamental Temperatures will climb to 2,500 degrees questions such Fahrenheit, but the science instruments will as why the solar remain at room temperature behind a 4.5-inch- atmosphere is thick carbon composite shield. dramatically Image courtesy of NASA hotter than the The mission was named in honor of Dr.
    [Show full text]
  • Los Motores Aeroespaciales, A-Z
    Sponsored by L’Aeroteca - BARCELONA ISBN 978-84-608-7523-9 < aeroteca.com > Depósito Legal B 9066-2016 Título: Los Motores Aeroespaciales A-Z. © Parte/Vers: 1/12 Página: 1 Autor: Ricardo Miguel Vidal Edición 2018-V12 = Rev. 01 Los Motores Aeroespaciales, A-Z (The Aerospace En- gines, A-Z) Versión 12 2018 por Ricardo Miguel Vidal * * * -MOTOR: Máquina que transforma en movimiento la energía que recibe. (sea química, eléctrica, vapor...) Sponsored by L’Aeroteca - BARCELONA ISBN 978-84-608-7523-9 Este facsímil es < aeroteca.com > Depósito Legal B 9066-2016 ORIGINAL si la Título: Los Motores Aeroespaciales A-Z. © página anterior tiene Parte/Vers: 1/12 Página: 2 el sello con tinta Autor: Ricardo Miguel Vidal VERDE Edición: 2018-V12 = Rev. 01 Presentación de la edición 2018-V12 (Incluye todas las anteriores versiones y sus Apéndices) La edición 2003 era una publicación en partes que se archiva en Binders por el propio lector (2,3,4 anillas, etc), anchos o estrechos y del color que desease durante el acopio parcial de la edición. Se entregaba por grupos de hojas impresas a una cara (edición 2003), a incluir en los Binders (archivadores). Cada hoja era sustituíble en el futuro si aparecía una nueva misma hoja ampliada o corregida. Este sistema de anillas admitia nuevas páginas con información adicional. Una hoja con adhesivos para portada y lomo identifi caba cada volumen provisional. Las tapas defi nitivas fueron metálicas, y se entregaraban con el 4 º volumen. O con la publicación completa desde el año 2005 en adelante. -Las Publicaciones -parcial y completa- están protegidas legalmente y mediante un sello de tinta especial color VERDE se identifi can los originales.
    [Show full text]
  • Space Almanac 2005
    SpaceAl2005 manac Stratosphere begins 10 miles Limit for turbojet engines 20 miles Limit for ramjet engines 28 miles Astronaut wings awarded 50 miles Low Earth orbit begins 60 miles 0.95G 100 miles Medium Earth orbit begins 300 miles 44 44 AIR FORCEAIR FORCE Magazine Magazine / August / August 2005 2005 SpaceAl manacThe US military space operation in facts and figures. Compiled by Tamar A. Mehuron, Associate Editor, and the staff of Air Force Magazine Hard vacuum 1,000 miles Geosynchronous Earth orbit 22,300 miles 0.05G 60,000 miles NASA photo/staff illustration by Zaur Eylanbekov Illustration not to scale AIR FORCE Magazine / August 2005 AIR FORCE Magazine / /August August 2005 2005 4545 US Military Missions in Space Space Force Support Space Force Enhancement Space Control Space Force Application Launch of satellites and other Provide satellite communica- Assure US access to and freedom Pursue research and devel- high-value payloads into space tions, navigation, weather, mis- of operation in space and deny opment of capabilities for the and operation of those satellites sile warning, and intelligence to enemies the use of space. probable application of combat through a worldwide network of the warfighter. operations in, through, and from ground stations. space to influence the course and outcome of conflict. US Space Funding Millions of constant FY06 dollars $50,000 DOD 45,000 NASA 40,000 Other Total 35,000 30,000 25,000 20,000 15,000 10,000 5,000 0 59 62 66 70 74 78 82 86 90 94 98 02 04 Fiscal Year FY NASA DOD Other Total FY NASA DOD Other
    [Show full text]
  • The Unique Evolutionary Dynamics of the SARS-Cov-2 Delta Variant
    medRxiv preprint doi: https://doi.org/10.1101/2021.08.05.21261642; this version posted August 7, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license . The unique evolutionary dynamics of the SARS-CoV-2 Delta variant Adi Stern*†1,2, Shay Fleishon*3, Talia Kustin1,2, Michal Mandelboim3,4, Oran Erster3, Israel Consortium of SARS-CoV-2 sequencingY, Ella Mendelson3,4, Orna Mor3,4, Neta S. Zuckerman†3 1 The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. 2 Edmond J. Safra Center for Bioinformatics, Tel Aviv University, Tel Aviv, Israel 3 Central Virology Laboratory, Public Health Services, Ministry of Health and Sheba Medical Center, Tel-Hashomer, Israel. 4 School of Public Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel- Aviv, Israel. * Co-equal authorship † Corresponding authors Y Israel Consortium of SARS-CoV-2 sequencing: Neta S. Zuckerman, Orna Mor, Efrat Dahan Bucris, Michal Mandelboim, Danit Sofer, Dana Bar-Ilan, Miranda Geva, Omer Asraf, Oran Erster, Gideon Rechavi, Efrat Glick-Saar, Nir Rainy, Chen Weiner, Reut Sorek-Abramovich, Yevgeni Yegorov, Anna Vishnevsky, Patricia Benveniste-Lekovitz, Abu Hamad Ramzia, Adina Bar Chaim, Ella Mendelson. NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. 1 medRxiv preprint doi: https://doi.org/10.1101/2021.08.05.21261642; this version posted August 7, 2021.
    [Show full text]
  • Comparing Futures for the Sacramento-San Joaquin Delta
    comparing futures for the sacramento–san joaquin delta jay lund | ellen hanak | william fleenor william bennett | richard howitt jeffrey mount | peter moyle 2008 Public Policy Institute of California Supported with funding from Stephen D. Bechtel Jr. and the David and Lucile Packard Foundation ISBN: 978-1-58213-130-6 Copyright © 2008 by Public Policy Institute of California All rights reserved San Francisco, CA Short sections of text, not to exceed three paragraphs, may be quoted without written permission provided that full attribution is given to the source and the above copyright notice is included. PPIC does not take or support positions on any ballot measure or on any local, state, or federal legislation, nor does it endorse, support, or oppose any political parties or candidates for public office. Research publications reflect the views of the authors and do not necessarily reflect the views of the staff, officers, or Board of Directors of the Public Policy Institute of California. Summary “Once a landscape has been established, its origins are repressed from memory. It takes on the appearance of an ‘object’ which has been there, outside us, from the start.” Karatani Kojin (1993), Origins of Japanese Literature The Sacramento–San Joaquin Delta is the hub of California’s water supply system and the home of numerous native fish species, five of which already are listed as threatened or endangered. The recent rapid decline of populations of many of these fish species has been followed by court rulings restricting water exports from the Delta, focusing public and political attention on one of California’s most important and iconic water controversies.
    [Show full text]