The computer programmes system and the nals language for numerical control for shipbuilding

COMMUNICATION No. 19 S August 1969 (S 5/102)

NEDERLANDS SCHEEPSSTUDIECENTRUM TNO

SHIPBUILDING DEPARTMENT LEEGHWATERSTRAAT 5, DELFT

THE COMPUTER PROGRAMMES SYSTEM AND THE NALS

LANGUAGE FOR NUMERICAL CONTROL

FOR SHIPBUILDING

(HET SYSTEEM VAN COMPUTER PROGRAMMA'S EN DE NALS TAAL

VOOR NUMERIEKE BESTURING TEN BEHOEVE VAN DE SCHEEPSBOUW)

by

DRS. H. LE GRAND

(Head of the computer department of the Netherlands Ship Model Basin)

VOOR WOO RD

Bij het merendeel der grotere werven is heden ten dage het systeem in gebruik waarbij op basis van schaal I op 10

teke-ningen het brandsnijproces optisch wordt gestuurd. Een volgende

stap, die in het buitenland op enige werven al gezet is, is dc

overgang naar numerieke besturing. .Hierbij kan men denken aan

brandsnijden, maar ook aan het vervaardigen van tekeningen,

het koud buigen van spanten en het buigen van platen. Het invoeren van een systeem van numerieke besturing houdt echter in dat de tot op heden gebruikte manieren voor het

ver-zamelen en bewerken van gegevens moeten worden verlaten.

,,Vertaling" van de gevestigde manier voor het verzamelen van deze gegevens zou tijdrovend zijn en aanleiding geven tot veel fouten.

Daarom is het van groot belang dat zowel ontwikkeling plaats

vindt aan de zijde van de elektronische ,,hardware" van het

nurneriek bestuurde werktuig alsmede ook grote aandacht wordt besteed aan de meest passende manier de gegevens ter

beschik-king te stellen, hetgeen de ,,software"-kant van het vraagstuk

vormt.

Bij het in gebruik nemen van een snellere en grotere computer

werd herschrijven van programma's nodig. Dat lëidde tot de introductie door het Nederlands Scheepsbouwkundig Proef-station van CALS (Computer Adapted Language for

Ship-calculations). Hiermede werd de grondsiag gelegd om de

ver-schillende programma's, die voor het grootste deel toen al be-schikbaar waren, maar waren ontwikkeld voor een computer

met beperkte mogelijkheden, met elkaar in verband te brengen

en te coördineren. Dit gold ook voor de eerder ontwikkelde

Autocode voor numerieke besturing, die niet in het nieuwe sys-teem paste.

Zodoende is de nieuwe taal NALS ontstaan, waarvan de naam

is afgeleid van Numerical control Adapted Language for the Shipbuilding. Door de volledige integratie van NALS in het

CALS-systeem, is het altijd mogelijk een beroep te doen op de

gegevens betreffende de scheepslijnen, d.m.v. de zgn. ,,data

bank", voor die-delen van de plaatconstructies waarvan de vorm

bepaald wordt door de geometric van de scheepsromp.

HET NEDERLANDS SCHEEPSSTLJDIECENTRtJM TNO

PREFACE

For the majority of the larger yards a great part of the flame cutting work is controlled optically by means of 1/10 scale

drawings. A further step, which in fact has been put already on

some yards abroad is the transition to numerical control

tech-niques. In that case one can imagine-about the process of flame

cutting as well about the drawing stage, cold frame bending

and plate forming.

Introducing systems of numerical control involves however

that the traditional way of gathering mformation must be left

Translation of the methods in use till now should be time con suming and error prone. Therefore both a package of electronic

hardware in the machine control equipment and sensible data

preparation, which forms the software side of the prOblem, is of upmost importance.

At the installatiOn of a faster computer with more possibil-ities recoding became necessary This leaded to the introduction by the Netherlands Ship Model Basin of the Computer Adapted Language for Shipcalculations (CALS). With this the foundation has been created to integrate the several programmes which were

for the greater part available at that time, however developed

for a computer with restrained facilities. This was also the case for the earlier developed Autocode for numerical control, which did not fit in the new system.

At that manner a new language NALS was born, which stands for Numerical control Adapted Language for the Shipbuilding.

Because NALS is fully integrated in the CALS system it is

always possible to call upon the reference file of hull form offset

data, the so-called data bank, for those portions of the plate

profiles which are governed by the hull geometry.

CONTENTS

page

Summary. 7

I Introduction 7

2 Characteristics and background of the CALS system 7

3NALS.

3.1 Brief description of the developments 8

3.2 The NALS-language 9

3.3 The basic NALS grammar

3.4 Data banks 11

3.5 The NALS compiler Ii

4 The lines fairing programme 11

5 Shell plate development . 12

6 Hydrostatic calculations 13

7 Concluding remarks 13

1 Introduction

Since the start of the computer centre of the Nether-lands Ship Model Basin (NSMB) in 1961 a great num-ber of programmes have become available and a skilled staff has been built up. More than 1000 of various

ship calculations were done for ships with widely dif-fering shapes. The staff obtained great experience in

the preparation of input data and the checking of

output data. Moreover the programmes now available on the Xl-Electrologica computer became very sophis-ticated.

Nevertheless the ever increasing number of orders and the further development of computer adaptations in the shipbuilding were two reasons for the NSMB to

switch to a faster and larger computer. At the end of

the year 1968, therefore, a Control Data 3300 was installed.

This made a recoding of all computer programmes necessary as the available programmes were written in the machine language of the Xl. This enabled NSMB to build up a new set of programmes incorporating new features that could not be realised earlier as a

conse-quence of the restrictions ofthe X1-computer. So there has now been a development ofa program-mepackage that takes advantage of the possibilities

of the CDC-computer and is based on the experience with the former Xl -computer programmes

All new programmes are written in Algol-60. In this way the programmes remain easily surveyable and rnod ifications and extensions are simply made. The pro-grammes that are now available or that will become

available before the end of 1969 are part of a large

complex of programmes that have the name CALS (Computer Adapted Language for Shipcalculations.) The general idea of the whoTepackage is a language in which all ship calculations can be written in a shape very close to the language the shipbUilder speaks.

THE COMPUTER PROGRAMMES SYSTEM AND THE NALS

LANGUAGE FOR NUMERICAL CONTROL FOR SHIPBUILDING

by

DRS. H. LE GRAND

Summary

The more extensive possibilities are described to make computer calculations for shipbuilding since the installation of the new CDC-3300 computer at the Netherlands Ship Model Basin; special attention has been given on the field which earlier was covered by the Autocode language, which was in fact very restricte4 because of the limited possibilities of the Xl computer.

Essential is to furnish the yards a possibility to prepare input for numerical control as easy as possible. Therefore a moresophisticated language NALS (Numencal control Adapted Language for the Shipbuildmg) has been developed Advantages are explained and emphasis is put on the availability of a data bank, which is fully integrated in the large complex of programmes that has the name CALS (Computer Adapted Language for Shipcalculations).

Part of the CALS project are the following calcula-tions:

Fairing of shiplines. Shellplate development.

Partprogramming language and nesting programme. Several hydrostatic calculations.

2 Characteristics and background of the CALS system

Before giving more details of the various programmes

that form the most important parts of the CALS

Delivering in time of the results of calculations for

the shipbuilding industry is very important. In this way the necessary computer time is in no way a bottle neck. The preparation of input data and the critical

review of the computer output and results derived is however time consuming Therefore, the programmes ask for an input that is easy to furnish. Moreover the

programmes must contain as much diagnostics as possible. The preparation of input data for the hull

fairing programme and the hydrostatic calculations is mostly done by the personnel of the computer centre

and in many cases also the input for the shellplate

development calculation is prepared by them. How-ever, the part programming of contourplates for the internal of the ship ought to be done by personnel of the yards. This job cannot be done by the people of the computer centre because it would be too difficult to find out how the shape of the plates is intended.

Therefore, a simple way of input is in the first place important for this programme. Moreover, the numeri-cally controlled flame cutting machine is used more and more nowadays and a language in which part

pro-gramming can be done is therefore an absolute need. This is the reason why NSMB did give high priority

8

to improvements of the originally developed Autocode language. The possibilities of the improved language (NALS) will be particularly emphasized in this report. Central point in the system of computer programmes is a data bank. The ship is divided in a few main com-ponents (e.g. hull, deckhousesforecastle and poop), which are subdivided in minor components. The data bank consists of a list of reference addresses. At these addresses one can find the data of frames, stern and

stem contours, deck lines, etc. All this information is stored on a mass storage device (tape, disk).

With a simple paging system information can be

taken from or stored into this data bank. The data

bank for a ship's hull is built up either by data coming from measurements (e.g. for hydrostatic calculations) or from the lines fäiring programme. These data can

be used by all programmes that are related to the hull shape of the ship.

All curves used in the new NSMB programmes and stored in the data bank are in a generalised (genspline) representation. Such a generalised spline is the mathe-matical analogon of the physical spline in use in the drawing room of the yards.

These splines are flexible bars kept in position by distinct weights. It can be seen from the Euler equation M = EI/R for the shape of this spline, that the cuive has continuous first and second derivatives across a point where a weight has been placed.

In the genspline used in the CALS project the equi-valent of this physical spline are polynomial elements with conditions of continuity at the given points. The

polynomials are cubic elements with continuity of

slope and curvature. To avoid difficulties in case of rotations as may occur e.g. in stability calculations, the curves are not representcd by cubic elements relative to a fixed system of axes but by cubic elements relative to a local system of axes with the xas along the chord between two points (fig. 1).

The formula used to represent such a cubic element is

Fig. I. Local system of axes.

y = 4x(Lx)Plx+Pr(Lx)}/L3,

where L is the chord length and P1 and Pr are two para-meters determined by the requirement of continuity of slope and curvature.

3 NALS

3.1 Brief description of the developments

The Netherlands Ship Model Basin entered the field

of numerical control in 1964 when an Essi-Aristo

numerical controlled drawing machine was installed. The Essi director can be combined just as well with a flame cutter. The differences between the numerical

control of a drawing machine and a flame cutting machine are not more than a few additional instructions for the flame cutting machine for the specifications of certain machine fUnctions as punch, torch on, etc.

When the NSMB started with the development of

an own language for the coding of contour plates this development was of importance for the production of drawings as well as the production of papertapes for numerical control of flame cutting machines.

For the representation of a drawing in Essi code the following has to be done:

The sequence of actions has to be fixed (the starting point of the drawing, the direction of rotation, pen up if a part of theline has to be passed over, pen down if the drawing has to be continued, etc.).

The figure has to be divided in simple geometric figures (straight lines, arcs).

In the Essi control system it is assumed that the tool (pen, flame cutter head) is in the starting point of the path to be followed. The tool can be directed along three kinds of paths:

a. Along a straight line. Then the coordinates of the

end point with respect to the starting point are

required, in other words the changes Ax and Ay of the coordinates x and y (see figure 2).

x Fig. 2. The ESSI parameters of the straight line are Lix, LXy

Fig. 3. The ESSI parameters of the arc are x, Ly,

x, v'

Along a circular arc. The coordinates of the

end-point of the arc section and of the centre of the circle with respect to the starting point of the circle to be followed are required. Moreover, the direc-tion of rotadirec-tion has to be indicated (see figure 3). Along a parabola. This possibility is rarely used and will, therefore, not be discussed here in further detail.

The data required to perform one of these three ele-mentary paths form a "data block" on the input tape closed by a block end symbol. In addition to the line parameters there are some commands as pen up, pen down, start and stop. These data are on the papertape unsigned numbers followed by a block end symbol and represent so an other kind of data blocks.

Each figure has to be composed of data blocks. When the measurements are conveniently arranged and the plate is not too complicated, simple additions and substractions suffice to get the increments of the datablocks. For more complicated drawings the amount of calculations to obtain other data blocks can be considerable.

3.2 The NALS language

To reduce the amount of preparations, a language has been developed to create the possibility to describe

complicated figures in a simple manner. A figure

described in this language can be punched on cards and fed into the computer. With a computer program-me the necessary Essi paraprogram-meters are calculated and a tape with Essi code is produced.

For the language earlier developed at the NSMB a compiler was written in the machine language of the

Xl-Electrologica computer. Due to the installation of the CDC 3300 computer a recoding of the pro-gramme was necessary. Because of the increasing adaptation of numerically controlled flame cutting

machines in the shipbuilding industry and profiting by the more extensive possibilities of the new computer, the language has been expanded extensively.

This language is called NALS (Numerical control Adapted Language for the Shipbuilding).

Some of the most important features of NALS are: - Points, straight lines and circles can be defined in several ways. This has the advantage that one can choose that way for which it is easiest to determine the parameters.

- Points of intersection and points of contact are

- Arbitrary curves (such as frames) can be defined by a table of coordinates.

- Names can be ascribed to points, straight lines, cir-cles and tables. This has the advantage that such a

point, line, circle or table has to be defined only once. For later use only the name is to be called. - Details of a drawing, that occur several times in

about the same form can be embedded in

sub-routines. The place, the rotation and a number of

dimensions can be kept as variables.

To have that detail drawn it is only necessary to

write down the name of the subroutine and to add the values of the variable parameters.

- A scale factor can be added to the programme. - It is possible to draw text at a drawing by means of

a single instruction.

- A semi-data bank can be built up. Geometric items

and parts of figures that occur often in a serie of

plates must be defined only once.

- Reference can be made to a data bank in whiáh the hull shape of the ship is stored.

- With simple additional cards a number of plates

can be nested together on a larger plate.

3.3 The basic NALS grammar

The elements of the NALS language are, vocabulary

words, punctuation symbols, constants, names and

hollerith information.

NALS vocabulary words have meanings specific to the NALS language. Most words resemble English equivalents.

Punctuation symbols are

+ - 0

Numbers may be integers and floating point num-bers.

Names are strings of symbols used to define geo-metric items.

Names must begin with an alphanumeric character. After that there may follow numeric and alphanumeric characters. The maximum of significant symbols is 8.

10

Hollërith information can be given to be drawn on

the plate e.g. as a specification. Blanks are ignored except in a string.

These elements of NALS are combined to construct statements.

There are two kind of statements: A geometric statements.

B. auxiliary statements. A. Geometric statements

Geometric statements are concerned with the

geo-metry of the figure. Geometric statements can be in

structions, for example, to do a part of a line or a

circle or to give a name to such a geometric item or both.

Geometric statements contain basically two parts: Major part

The major part consists of a vocabulary word

describing something about the geometry. Minor part

The minor part gives additiOal information

specifying the geometry.

Examples: LINEOI +0 +0 + 100 +0

This is a straight line (LINE) defined by two points (01) (major part). These two pointsare +0+0 and ± 100+0. CIRCLEO4.L 1 .LEFT. L2.LEFT

100

This is a circle (CIRCLE) tangent to two straight lines and with a prescribed radius (04) (major part).

The lines Li and L2 are defined earlier. The centre is at the left side of both lines. The radius is +100 (minor part). POINTO1 +37 +80 point defined by its coordinates + 37, + 80.

In this way points can be defined in six ways, lines in eight ways and for circles there are seven possibilities. Then there is the instruction TABEL, followed by a number of points defining a curve.

All these geometric items can be preceded by a name which is then assigned to it. If they are only preceded by the word DO, or by nothing the geometric item is carried out. The third possibility is the word

DO followed by a name. In this case both the geo-metric adaptation is performed and the mentioned name is assigned to the line, arc, parabole, etc.

Example 1: Ci.CIRCLEO1 +0 +0 + 100. The circle

with centre +0 ±0 and radius 100 is

called CI. Instead of the full geometric statement it is from now possible to use only the word Cl, e.g. DO.CL

Example 2; DO.LINEO2 +0 +0 +90. This means

"do" a line through the point +0 ±0 and having an angle of 90 degrees with respect to the positive x-axis.

Example 3: DO.Ll.LINEO2 +0 +0 +0. Now the x

as is determined and given the name Li.

B; Auxiliary stdtements

These statements are used for auxiliary information. Examples: PENIJP.

PENDOWN.

TEXT (SECTION 17), the string SECTION 17 is Written on the paper.

FIN!, end of a figure.

SCALE, number. If another scale then 0.1 is wanted this can be stated by this in-struction.

Statements can be combined in subroutines. This

offers the possibility to accomodate part figures in a subroutine, for instance, manholes.

The general outline of a subroutine is: Name. BEGIN

END.

The subroutine can be called by its name

After the word BEGIN the word POSITION can follOw, followed by a geometric point and a number.

This point defines the place where the figure defined in the subroutine has to be placed; the number gives the angle of rotation.

The possibility exists to vary items at each call of a subroutine This can be done by substituting the word TAKE instead of the item. At the call of the subroutine the real value or parameter is added to the name of the subroutine. This possibility yields for numbers and all minor words, like LEFT, POS, etc.

Example: HOLE.BEGIN.POSITION.TAKE.

TAKE +0

LINEO2.TAKE + 0 TAKE END.

The call of that subroutine can be: HOLE + 700 ± 800 ± 50 Ni.

if Ni is the name of a number, representing the angle of rotation.

Subroutines are selfcontaining blcks. This means that names used in subroutines are only valid in that sub-routine. This opens the possibility that different per-Sons can do part programming for the same plates. The programmer coding the main programme can use subroutines coded by another without the risk that

both use the same name for different things.

1 HOLE.BEGIN. POSITION. TAKE+O+()

2 LINEO2+O+O.i-C)

3 Ni. IUNBER TAKE DO. Cl. CIRCLE015ON1-5()

4 LINEO8.Ci.LEFP+O 5 CIRCLEO].+150N1-5() 6 LINEO2+1504O+9OEND. 7 AFtT+O+O 8 DO.Ll LINEO1+O+O+100+Q 9 HOLE+500+200 10 LI. 1]. HOLE+900+2(X)L1. 12 HOLE+1300+225 13 Li. 14 _{CIRCLEO1+1700+O..75} 15 LINEO2+17(X)+O+90 16 _{CIRCLEO1+1700+l2oo-75} 17 LINEO2+O+1.200+C) 18 _{L-INEO2+O+O+90} 19 ENDPOINT+O+O ?O FINI.

Fig. 4. Example of input in NALS.

Fig. 5. Output resulting from example of fig. 4 as given by the ESSI-Aristo numerical controlled drawing machine.

3.4 Data banks

All names assigned in a part programme are only valid in that pait programme. However, the possibility exists to maintain information over a batch of part

pro-grammes. This can be done by the instruction COM-MON. All items defined before the word COMMON

remain valid till the end of the computer run. (For

instance definitions of lines and whole subroutines.) If it is necessary to end this situation then the word

COMMON E can be used.

When the ship has been faired before or when

hy-drostatic calculations were made before, NALS can refer to the hull shape in this way stored in the com-puter. This can be done by the instruction .FRAMENR, number.

In that case framesections need not be defined by tables but can be called up directly from the computer storage (data bank).

3.5 The NALS compiler

The compiler of NALS for the CDC 3300 exists of the following parts.

I. reading of part programmes from cards listing of the text

collecting words, numbers and text construction of the object programme

5 analysis of the text and print out of diagnostics of

possible errors in the language syntax

executive phase,. that calculates intersections etc. post processor where the papertape is produced

The compiler is written in Algol-60. This makes it

easy to bring in new features and to make modifica-tions. If, for instance, a punched tape with a different

code is wanted, changes need only be made in the post processor.

A great number of possible diagnostics is very im-portant for a good service of the computer centre All syntax errors will be found then by the computer and

printed with an indication of the kind of error and the line in the text where it occurs The pnnt out of

the text contains the same line numbers. Mostly all syntax errors can be found in one computer run. Be-cause the inpUt is on cards, corrections can be made

easily.

In the same way the execution phase contains a num-ber of diagnostics (e.g. if a line does not intersect with a circle).

An additional feature of the compiler is the calcula

tion of the length of the drawn lines (respectively

cutting path). Thus the yard can set up a planning for the cutting machine. The area of the plate is calcu-lated also. In combination with the specific weight this

results in the weight of the finished plates.

4 The lines fainng programme

The lines fairing programme of the NSMB has now -been used for more than 150 ships. The method used

has appeared to be a good one The new CDC pro gramme is based also on the same principle as the

Xl programme However a number of improvements are made to make it possible to include those ships that gave trouble due to their particular shape.

12

The programme fairs the ship lines, puts the faired lines in the data bank and prints a table of offsets. In addition it is possible to produce a lines plan on the drawing machine.

The basic idea of the fairing process has been the simulation of the method by hand as used on the yard. Fairing, in the traditional sence was performed using a thin flexible bar, the spline, that can be fixed in a certain position by weights.

From the differential equation for a spline, given

earlier, it follows clearly that discontinuities in the

third derivative may occur at these points where the weights are placed. To get a smooth line with a spline the discontinuities in the third derivative should be small Lifting of weights gives some check on the

dis-continuity in the third derivative at the point con-sidered.

It seems acceptable to define fairing mathematically by the condition that the variation of the third deri-vative along the curve is small, so the fôutth derideri-vative should be small. Mathematically there is no need to take the fourth derivative especially. In general we may define k'th order fairing by the requirement that the k'th derivative of the curve is small.

'I

'2

the k'th divided difference at point f1 may be written in the form

k Ic

with

D1= I/fl (xx+,)

jo

lj

where the expression fix1 stands for the continuous product

XoXlX2..Xk

The condition of smoothness of the fàired points can be expressed by the requirement that the sum of the squares of the k'th divided differences is small i.e.

Nk( Ic

is small.

'°

U°

The condition of conservation of the original shape of the curve on the other hand demands that the faired

points should be close to those given, so

N

(yf

i=O

The fairing process is now defined as the miniinisation of a linear combination of these two coditions.

The hull form is faired by successive fairing of a restricted number of waterlines, buttocks and sections. it has appeared that the choice k = 5 is well suited for these ship lines. After each fairing cycle of waterlines, buttocks and sections the corrections are considered. If these are smaller than 1 mm the fairing process is stopped, otherwise it is repeated. From the faired waterlines and sections in the transformed coordi-nates the table of offsets can be calculated using a

special third degree interpolation formula.

5 Shell plate development

The sheliplate development programme of the NSMB is a simulation of the cross mould method used on the shipyard. In addition to the data of the hull the

pro-gramme requires the seams and butts to define the

plates. Output is:

1.

SPRNTENLSTNR aso

2.

Fig 6. Output of a lines plan on the drawing machine.

3. 4. Introducmg a given set of (N+ 1) points x1, y (i =0,

1, ..., N), the faired points are supposed to be

x,

f (i

defined since the curve is given by discrete pOints only. Instead the k'th divided difference is used, being an approximation for the k'th derivative if the points 7.

lie on an analytical curve sufficiently close together,

number of the sheliplate as specified length of contour of the plate area of the plate

breadth and length of the smallest circumscribed rectangle

area of this rectangle

x- and y-coordinates of butts and frames with required elongation at the respective spots (x, y

coordinate with respect to the rectangle)

x and y-coordinates of other expanded lines (if

S. 41. 41

4. 1411

Fig. 7. Drawn output of shell plate development programme.

Plate thicknesses are taken into account in the calcu-lation. The computer produces a papertape which can

be used for the electronic drawing machine or a

flame cutting machine.

With another programme

6 Hydrostatic calculations

The following programmes for hydrostatic calculations are now available:

- Calculation of hydrostatic curves. - Transverse stability calculation. - Trim diagram calculation. - Launching calculation. - Damage stability calculation. - Ullage and sounding calculation.

- Wave bending moment calulation. - Calculation of curve of floodable lengths.

- Programmes for producing a drawing of several of the above mentioned calculations.

These programmes are being recoded now for use on the CDC computer. They make use of the data bank. In many cases, however, the lines fairing programme will not have preceded one of these above calculations. Then the data bank is built up from measurements lifted from a lines drawing.

The programmes make use of the genspline repre-sentation of the curves. This means that with a

mini-mum of measured points a maximini-mum of accuracy

can be obtained.

Input data are checked by new subroutines and by drawings on the plotter connected to the computer.

Very complicated hull forms can be dealt with now e.g. ships with receding parts in the frames (fig. 8).

I--, LJ LIh '1 U L1 --, .LjJEJ

L.

a

Li

H 'J

haLI

Fig. 8. Checking of input by a plotter connected to the computer.

14

7 Concluding remarks References

At the installation of the CDC 3300 computer at the NSMB a recoding of the X1-Electrologica

program-mes for

The whole gist of the matter is a data bank in which the hull shape of a ship is stored. Most proglammes

have maintained their old setup because their ap-plicability appeared to be of great value.

The pi ogramme for the coding of contour plates, however, was totaly revised.

The language NALS offers now a very powerful facility in the field of numerical control.

BAIcxaR, A. R., Application of a computer to some

ship-building problems.

I.S.P. Vol. 12 - No. 130 - June 1965.

Computer calculations for the shipbUilding Industry.

Un-published NSMB report.

LE GRAND, H, The NSMIB Autokode. Unpublished NSMB report.

LE GRAND, H. and P. KiFis, Het verwerken van numerieke scheepsbouwproblemen bij het rekencentrum van het

Neder-landsch Scheepsbouwkundig Proefstation. Schip en Werl,

PUBLICATIONS OF THE NETHERLANDS SHIP RESEARCH CENTRE TNO PUBLISHED AFTER 1963 (LIST OF EARLIER PUBLICATIONS AVAILABLE ON REQUEST)

PRICE PER COPY DFL.

10,-M = engineering department S = shipbuilding department C = corrosion and antifouling department Reports

57 M Determination of the dynamic properties and propeller excited

vibrations of a special ship stem arrangement. R. Wereldsma, 1964.

58 S Numerical calculation of vertical hull vibrations of ships by

discretizing the vibration system, J. de Vries, 1964.

59 M Controllable pitch propellers, their suitability and economy for large sea-going ships propelled by conventional, directly coupled engines. C. Kàpsenberg, 1964.

60 S Natural frequencies of free vertical ship vibrations. C. B.

Vreug-denhil, 1964.

61 S The distribution of the hydrodynamic forces on a heaving and pitching shipmodel in still water. J. Gerritsma and W.

BeUkl-man, 1964.

62 C The mode of action of anti-fouling paints: Interaction between anti-fouling paints and sea water. A. M. van Londen, 1964.

63 M Corrosion in exhaust driven turbochargers on marine diesel

engines using heavy fuels. R. W. Stuart Michell and V. A. Ogale,

1965.

64 C Barnacle fouling on aged anti-fouling paints; a survey of perti nent literature and some recent observations. P. de Wolf, 1964. 65 S The lateral damping and added mass of a horizontally oscillating

shipmodel. G. van Leeuwen, 1964.

66 S Investigations into the strength of ships' derricks. Part. I. F. X.

P. Soejadi, 1965.

67 S Heat-transfer in cargotanks of a 50,000 DWT tanker. D. J. van der Heeden and L. L. Mulder, 1965.

68 M Guide to the application of Method for calculation of cylinder liner temperatures in diesel engines. H. W. van Tijen, 1965.

69 M Stress measurements on a propeller model for a 42,000 DWT

tanker. R. Wereldsma, 1965.

70 M Experiments on vibrating propeller models. R. Wereldsma, 1965.

71S Research on bulbous bow ships. Part II. A. Still water

perfor-mance of a 24,000 DWT bulkcarrier with a large bulbous bow. W. P. A. van Lammeren and J. J. Muntjewerf, 196.5.

72 S Research on bulbous bow ships. Part. H. B. Behaviour of a

24,000 DWT bulkcarrier with a large bulbous bow in a seaway. W. P. A. van Lammeren and F. V. A. Pangalila, 1965. 73 S Stress and strain distribution in a vertically corrugated bulkhead.

H. E. Jaeger and P. A. van Katwijk, 1965.

74 S Research on bulbous bow ships. Part. I. A. Still water investiga-tions into bulbous bow forms fOr a fast cargo liner W. P. A. van

Larnineren and R. Wahab, 1965.

75 S Hull vibrations of the cargo-passenger motor ship "Oranje Nassau", W. van Horssen, 1965.

76 S Research on bulbous bow ships. Part I. B. The behaviour of a fast cargo linerwith a conventional and with a bulbous bow in a

sea-way. R. Wahab, 1965.

77 M Comparative shipboard measurements of surface temperatures

and surface corrosion in air cooled and water cooled turbine outlet casings of exhaust driven marine diesel engine

turbo-chargers. R. W. Stuart Mitchell and V. A. Ogale, 1965. 78 M Stern tube vibiation measurements ofa cargo ship with special

afterbody. R. Wereldsrna. 1965.

79 C The pre-treatment of ship plates: A comparative investigation

on some pre-treatment methods in use in the shipbuilding indus-try. A. M. van Londen, 1965.

80 C The pre-treatment of ship plates: A practical investigation into

the influence of different working procedures in over-coating

zinc rich epoxy-resin based pre-construction primers. A. M. van Londen and W. Mulder, 1965.

81 S The performance of U-tanks as a passive anti-rolling device.

C. Stigter, 1966.

82 S Low-cycle fatigue of steel structures. J. J. W. Nibbering and

J. van Lint, 1966.

83 S Roll damping byfreesurface tanks. J. J. van den Bosch nd J. H;

Vugts, 1966.

84 S Behaviour of a ship in a seaway, J. Gerritsma, 1966.

85 S Brittle fracture of full scale structures damaged by fatigue. J. J. W. Nibbering, J. van Lint and R. T. van Leeuwen. 1966. 86 M Theoretica evaluatiOn of heat transfer in dry cargo ship's tanks

using thermal oil as a heat transfer medium. D. J. van der

Heeden. 1966.

87 S Model experiments on sound transmission from engineroom to accommodation in motorships. J. H. Janssen, 1966.

88 S Pitch and heave with fixed and controlled bow fins. J. H. Vugts,

1966.

89 S Estimation of the natural frequencies of a ship's double bottom by means of a sandwich theory. S. Hylarides, 1967.

90 S Computation of pitch and heave motions for arbitrary ship forms. W. E. Smith, 1967.

91 M Corrosion in exhaust driven turbochargers on marine diesel en-gines using heavy fuels. R. W. Stuart Mitchell, A. J. M. S. van

Montfoort and V. A. Ogale, 1967.

92 M Residual fUel treatment on board ship. Part II. Comparative

cylinder wear measurements on a laboratory diesel engine using filtered or centrifuged residual fueL A. de Mooy, M. Verwoest and G. G. van der Meulen, 1967.

93 C Cost relations of the treatments of ship hUlls and the fuel con-sumption of ships. H. J. Lageveen-van Kuijk, 1967.

94 C Optimum conditions for blast cleaning of steel plate. J. Remmelts,

1967.

95 M Residual fuel treatment on board ship. Part. I. The effect of

cen-trifuging, filtering and homogenizing on the unsOlubles in

residual fuel. M. Verwoest and F. J. Colon, 1967.

96 S Analysis of the modified strip theory for the calculation of ship motiOns and wave bending moments. J. Gerritsma and W.

Beu-kelman, 1967.

97 S On the efficacy of two different roll-damping tanks. J. Bootsma and J. J. van den Bosch, 1967.

98 S Equation of motion coefficients for a pitching and heaving des-troyer model. W. E. Smith, 1967.

99 S The manoeuvrability of ships on a straight course. J. P. Hooft,

1967.

100 S Amidships forces and moments on a GB = 0.80 "Series 60"

model in waves from various directions. R. Wahab, 1967. 101 C Optimum conditions for blast cleanmg of steel plate Conclusion

J. Remmelts, 1967.

102 M The axial stiffness of marine diesel engine crankshafts. Part I. Compa.rison between the results of full scale measurements and

those of calculations according to published formulae. N. J.

Visser, 1967.

103 M The axial stiffness of marine diesel engine crankshafts. Part II. Theory and results of scale model measurements and comparison with published formulae. C. A. M. van der Linden, 1967. 104 M Marine diesel engine exhaust noise. Part I. A mathematical model.

J. H. Janssen, 1967.

105 M Marine diesel engine exhaust noise. Part II. Scale models of

exhaust systems. J. Buiten and J. H. Janssen, 1968.

106 M Marine diesel engine exhaust nOise. Part. IlL Exhaust sound

criteria for bridge wings. 3. H. Janssen en J. Buiten. 1967.

107 5 Ship vibration analysis by finite element technique. Part. I.

General review and application to simple structures, statically loaded. S. Hylarides, 1967.

108 M Marine refrigeration engineering. Part I. Testing of a

decentral-ised refrigerating installation. 3. A. Knobbout and R. W. J.

Kouffeld, 1967.

109 5 A comparative study on four different passive roll damping

tanks. Part I. J. H. Vugts, 1968.

110 S Strain, stress and fiëxurë of two corrugated and one plane

bulk-head subjected to a lateral, distributed load. H. E. Jaeger and

P. A. van Katwijk, 1968.

111 M Experimental evaluation of heat transfer in a dry-cargo ships' tank, using thermal oil as a heat transfer medium. D. J. van der

Heeden, 1968.

112 5 The hydrodynamic coefficients for swaying, heaving and rolling cylinders in a free surface. J. H. Vugts, 1968.

i 13 M Marine refrigeration engineering Part II. Some results of testing a decentraliséd marine refrigerating unit with R 502. J. A. Knob-bout and C. B. Colenbrander, 1968.

115 S Cylinder motions in beam waves. J. H. Vugts, 1968.

116 M Torsional-axial vibrations of a ship's propulsion system. Part I. Comparative investigation of calculated and measured torsional-axial vibrations in the shafting of a dry cargo motorship. C. A. M. van der Linden, H. H. 't Hart and E. R. Dolfin, 1968.

117 S A comparative study on four different passive roll damping

tanks. Part II. J. H. Vugts, 1969.

118 M Stern gear arrangement and electric power generation in ships propelled by contr011able pitch propellers. C. Kapsenberg, 1968. 119 M Marine diesel engine exhaust noise. Part IV. Transfer damping

data of 40 modelvariants of a compound resonatorsilencer. J. Buiten, M. J.A. M. de Regt and W. P. H. Hanen, 1968. 120 C Durability tests with prefabrication primers in use of steel plates.

A. M. van Londen and W. Mulder, 1969.

121 S Proposal for the testing of weld mctal from the viewpoint of brittle fracture initiation. W. P. van den Blink and J. J. W.

Nibbering, 1968.

122 M The corrosion behaviour of cunifer 10 ailoys in seawaterpiping-systems on board ship. Part I. W. J. J. Goetzee and F. 1. Kievits,

1968.

123 M Ma ile refrigeration engineering. Part HI. Proposal for a

specifi-cation of a marine refrigerating unit and test procedures. J. A.

KnObbout and R. W. J. Kouffeld, 1968.

125 S A proposal on noise criteria fOr sea-going ships. J. Buiten, 1969. 126 S A proposal for standardized measurements and annoyance rating

of sinilultaneous noise and vibration inships. J. H. Janssen, 1969. 127 S The braking of large vessels H. H. E. Jaeger in collaboration with

M. Jourdain, 1969.

128 M Guide for the calculation of heating capacity and heating coils for double bottom fuel oil tanks in dry cargo ships. D. J. van der Heeden, 1969.

130 M Marine diesel engine exhaust noise. Part V. Investigation of a double resonatorsilencer. J. Buiten, 1969.

Communications

11 C InvestigatiOns into the use of some shipbottom paints, based on scarcely saponifiable vehicles (Dutch). A. M. van Londen and P. de Wolf, 1964.

12 C The pre-treatment of ship plates: The treatment of welded joints

prior to painting (Dutch). A. M. van Londen and W. Mulder,

1965.

13 C Corrosion, ship bottom paints (Dutch). H. C. Ekama, 1966.

14 S Human reaction to shipboard vibration a study of existing

literature(Dutch). W. ten Cate, 1966.

15 M Refrigerated containerized transport (Dutch). J. A. Knobbout,

1967.

16 S Measures to prevent sound and vibration annoyance aboard a seagoing passenger and carferry, fitted out with dieselengines (Dutch). J Buiten, L H. Janssen, H. F. Steenhoek and L. A. S.

Hageman, 1968.

17 S Guide for the specification, testing and inspection of glass reinforced polyester structures in siipbuilding (Dutch) G

Hamm, 1968.

18 S An experimental simulator for the manoeuvring of surface ships. J. B. van den Brug and W. A. Wagenaar, 1969.

19 S The computer proammes system and the NALS language for