CHEMISTRY FOR ENGINEERING MAJORS
CHEMISTRY FOR ENGINEERING MAJORS CH 201
Popular in Course
Popular in Chemistry
This 4 page Class Notes was uploaded by Brandyn Altenwerth V on Monday October 19, 2015. The Class Notes belongs to CH 201 at Oregon State University taught by Staff in Fall. Since its upload, it has received 8 views. For similar materials see /class/224560/ch-201-oregon-state-university in Chemistry at Oregon State University.
Reviews for CHEMISTRY FOR ENGINEERING MAJORS
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/19/15
Chapter one Introduction The world production of sh has grown steadily in recent times and now it stands at more than 90 million tonnes per annum However the rising global production conceals the fact that individual populations rise and fall On occasions the fall is a dramatic collapse which has severe consequences for those who are supported by the local lishery Beverton 1990 We shall not discuss the causes of such events except to say that longterm success in shing depends upon knowledge of the exploited population whose size and distribution may change unpredictably from year to year Much of this knowledge comes from the investigation of sh in their natural environ ment This book is primarily concerned with the use of sound for the observation and monitoring of aquatic life in the sea and fresh waters Al the wavelengths which we can see light does not penetrate more than a few metres below the water surface and much less when the medium is loaded with suspended solids or biola such as plankton However sound waves travel much longer distances through water 39l hus acoustic in struments which transmit and receive sound waves are capable of detecting lish or other objects far beyond the range of vision Because of this acoustic technology has had a major impact on shing The information provided by sonars and echosounders is an important factor in the efficiency of modern fishing operations Purse seining and pelagic trawling are two methods which depend upon the skilful interpretation of acoustic data to ensure success In sheries research too acoustic techniques have become increasingly important over the years With sonar it is possible to search a large volume of water in a short time other sampling methods such as trawl shing are very slow by comparison Acoustic echoes may be observed from sh anywhere in the water column except the nearsurface region and just above the seabed Sonar has contributed greatly to our understanding of life in the sea and fresh waters especially the distribution of animals in space Introduction and time Many experimental investigations have been reported in the literature As a few examples we note the sizing of sh by exciting resonance of the swimbladder Holliday 1977a the use of automatic transmitters or pingers Hawkins at 11 1974 and transponders Arnold and Metcalfe 1989 to monitor the movements of sh and the study of sh behaviour Olsen et 11 1983ab The measurement of sh abundance is probably the most important application of acoustics in sheries research MacLennan 1990 The management of most sheries depends upon controlling the quantity caught in relation to the size of the exploited population Gulland 1983 To do this it is necessary to estimate the current size abundance of the popu lation or that in the recent past The acoustic method records the sh echoes and estimates the abundance as the quantity of sh which would Thus acoustic methods of observation are unsuited to the at sh and other species which live in close association with the seabed Fortunately many important species are found in midwater notably the herring family Clupeidae the mackerels Scombridae the anchovies Engraulidae and the salmonids Salmonidae In appropriate circumstances an acoustic survey provides a synoptic estimate of the abundance which is independent of the shery Sound also has a natural importance for sh and the mammals that live in water They use it as a means of communication and detection of prey This aspect of underwater acoustics has also been the subject of much research Hawkins 1986 11 A BRIEF HISTORY Leonardo da Vinci is credited with the earliest known reference to under water sound In a notebook dated 1490 he observed that by listening to one end of a long tube with the other end in the sea 39you will hear ships at a great distance39 Urick 1983 The speed of underwater sound about 1450msquot was rst measured by Colladon and Sturm in 1827 They Geneva in Switzerland However practical applications had to await the development of electrical transducers and receivers In 1918 as a result of research motivated by the First World War it was discovered that sub marines could be detected by listening for the echo of a sound transmission A brief history 3 Kimura 1929 described the rst successful experiment on the acoustic1 detection of sh He installed a transmitter and a separate receiver Dalian used to cultivate sh Fig 11 The sound was transmitted in a d The and detected after re ection from the OppOSlte Side of t 1e pint 1 kHz transmission was continuous at 200 kszflg laquriiilllcy brill 215 lit 11 SChOOl so that the recti ed signal would be an i e 6 p0 39 of Pagrosomus major about 25 bslh lfngjtlti l gggr 133112 fflingetellirzt the received sound was noticea y 5 ur e although reliable detection depgnfiied on Shte 53112 1 hffujgzpadt is I 39 this ex eriment the s were e ec I fjdirllllvlarlintransmisljsion caused by their movement The alternaltn e m1th no echo detection was rst reported by Sund 1935 who publis eS ecd lied a of the cod Gadus morhua in the Lofoten region of Norway Llll d on the 16 kHz echosounder with a magneto strictive transducer msta e S ected research vessel Iohan Hjort This equipment revealed many un sug to a features of the sh distribution notably that the cod were cfon ne narrow layer 10 m thick at a constant distance below the sug ace d world Another period of rapid development occurred during the econI of the War after which shermen soon discovered the civ1lian Lotefntga BritiSh instruments developed by the Hilitaryb39fhe pittgiiecr1lgeltorTh p0 eNer and skipper Ronnie Balls is especia y no a e m i deSi ed 39 of sonars continued to improve as new lustruments were g 22231 for sh detection Many different kinds of I sona1 aagew io employed in shing from the simple echosounder to scanning s I Receiver H 39 Projector P 4 43m u 39 the rst acoustic detection of sh 39 A aratus used by Kimura 1929 In I K d fronflfhe projector P is reflected by the far Slde of a pond 155 45lngudiefgf1tll1w detected by the receiver R Fish passing through the beam cause t e amp 1 received signal to uctuate 4 Introduction provide a radar like display in two dimensions The introduction of ech grams displayed in colour has greatly improved the perception of si of strength Fishermen have exploited these developments with great skillgrrll l some extent they can deduce the species composition of targets usuall b0 lig zrpretinlg the echograms in conjunction with other information aboutyth compiqgli g dl39IOWCVer the problem of target identi cation has not been Acoustic methods of abundance estimation were rst applied around 1970 notably the technique of echo integration proposed by Dra esund and Olsen 1965 In the early days the results that could be obtainefi subject to large errors The calibration methods of the time were im rew39ere and the target strength of important species was uncertain Inlfe Cl39se39 theoretical and experimental investigations in the 19703 and 19808 lndntle a better understanding of what acoustic techniques could and could noet d 0 High performance scienti c echosounders were introduced with larger do nhamic range more stable gain characteristics and better compensation if t e propagation losses Calibration is no longer a limiting factor rovid d 39t is done in the recommended way Foote et al 1987 New types 13f acodstilc fiinitruments have been developed which allow the target strength of Wild 5 to be measured directly notably the dualbeam and splitbe echosounders These instruments have also been used for abundance atr n mation39by echo counting a technique which is applicable to dis e33 populations of sh Echocounting has been particularl su f l 88 study of sh in lakes and rivers y CCCSS u m the 12 SYNOPSIS This book has been written primarily for postgraduate students rofess39 l scientists and administrators concerned with shery manaygme tuTrba prmCiples of underwater acoustics are covered to the extent gneceslls te show the advantages and disadvantages of acoustic methods in O investigations Bearing in mind that many readers will have a back r 6rd Ln the biological sciences and may be less familiar with mathematigcsouxe thave tried to explain the subject in words and illustrative graphics to reduce e reliance on mathematical shorthand which is rather too common 39 acoustic publications However some theory is essential for the r m understanding of sound sh as targets and the statistical problems are common to acoustic and other kinds of survey A list of s mbol IC39 provrded at the beginning of each chapter Throughout the 300k Sthls emphasrs is on acoustics as an applied science Practical advice is Web 6 51 filse of acoustic instruments in the eld and the solution of Emblem prOgcChare often ignored by those who prefer the purely theoretical ap Synopsis 5 Chapter 2 is an introduction to the concept of energy transmission by sound waves and the remote detection of targets We discuss the generation of sound by transducers the propagation of waves the scattering properties of targets and the formation of echoes The competing requirements of resolving close targets and detection at long range are considered in relation to the frequency of the sound waves The operating principles of modern acoustic instruments are described in Chapter 3 The simple echosounder transmits sound in a single beam which permits the range but not the direction of targets to be deter mined More sophisticated devices are capable of angular resolution They include dualbeam splitbeam multibeam and sectorscanning sonars Wide band sonar is a recent development which offers the possibility of identifying targets from the spectrum of echoes The calibration of acoustic instruments is discussed Practical advice is given on how to perform the calibration in accordance with internationally accepted stan dards In Chapter 4 we review a number of diverse topics to do with physiology and the behavioural importance of sound for aquatic life We discuss the sensitivity of hearing the production of sound by animals and the remark able sonar capability of the Cetacea The biological consequences of under water explosions have been studied experimentally and we show how the risk of sh mortality can be assessed Another topic is the phenomenon of swimbladder resonance which has been proposed as a means of determining sh size The same theory is relevant to the acoustics of plankton which may be studied by the simultaneous use of sonars operating at widely separated frequencies Chapter 5 is concerned with the observation and measurement of sh ie how to interpret the information provided by acoustic instruments We begin with the simple echogram and the technique of school counting The measurement of sh density relies upon more advanced techniques notably echo counting and echo integration The density is supposed to be propor tional to the integral of the echo energy returned from the depth channel of interest This assumption depends upon the linearity principle which is central to the theory of sheries acoustics The evidence in support of linearity is discussed The target strength of sh is reviewed in Chapter 6 Experimental techniques for measuring the target strength are described The swimbladder is the dominant sound re ector in those species having one Accordingly sh targets may be classi ed as physoclists bladder closed physostomes bladder open or those with no bladder Within each category sh of the same size have similar target strengths on average but there is much residual variation which emphasizes the stochastic nature of target strength Published experimental results are presented in a form suitable for easy reference 6 Intrmlmrtinu The last two chapters deal with the practice of acoustic surveying to measure the abundance and distribution of sh The emphasis is on the practical problems that arise in applying the theoretical principles discussed earlier in Chapter 7 we consider the equipment required for acoustic surveys the design of the cruise track and the sampling strategy to make the best uSe of the available time Live sh calibration and intersiiip comparison are two methods for testing the overall performance of the survey equipment in the lield although they are not a substitute for the recommemlcd calibration procedure in Chapter 8 we discuss the analysis of the data collected during the survey The aim is to calculate abundance estimates within deiined conlidenee limits liirst the echointegrator data must be partitioned between species and the surveyed area may have to be straiilied depending on the stationarity of the lish density An ccho integ rator conversion factor is calculated for each species and stratum from which the density samples are obtained The total abundance is estimated from the observed densities There are a number of approaches to this problem which is complicated by the statistics of spatial correlation 6 describe contour mapping kriging and numerical methods based on rectan gular grid strata The various factors which contribute error are discussed and we show how the overall accuracy of the abundance estimate can be assessed The results obtained from acoustic surveys are compared with those of alternative methods again to indicate the accuracy that can be expected in typical circumstances In compiling the references we have concentrated on the many pub lications which have appeared in the past 15 years or so avoiding obsolete material but including key references to earlier work that laid lhc foun dations of modern lisheri acoustics Sec Verema 1985 for a more complete bibliography of earlier work
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'