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To the question about checking parameters of code current of rail circuit

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III I N T E R N A T IO N A L C O N F E R E N C E

TRANSPORT S Y S T E M S T E L E M A T I C S TST'03

Z E S Z Y T Y N A U K O W E P O L IT E C H N IK I Ś L Ą S K IE J 2003

T R A N S P O R T z.51, n r kol. 1608

r a il circu it, device, c o d e c u rr e n t p a r a m e te r s c o n tro l

Vladimir I. G A V R IL Y U K 1 Tatyana N. S E R D Y U K 2

T O T H E Q U E S T I O N A B O U T C H E C K I N G P A R A M E T E R S O F C O D E C U R R E N T O F R A IL C I R C U I T

T h is p a p e r d e als w ith th e q u estio n o f d efin itio n o f c o d e cu rre n t p a ra m e ters and sp ec tru m interference in rail n et. It is p ro p o se d th e h a rd w a re -so ftw are co m p le x fo r this p u rp o se. It is re a lised o n the base o f p e rso n al c o m p u te r a n d m ic ro p ro c e sso r tech n iq u es.

R O Z W A Ż A N I A N A T E M A T P A R A M E T R Ó W K O N T R O L N Y C H P R Ą D U K O D O W A N E G O W O B W O D A C H T O R O W Y C H

A rty k u ł o m a w ia k w e stię d efin icji p a ra m e tró w p rą d u k o d o w a n eg o i z ak łó ce ń w id m a w rz e cz y w iste j siec i k o le jo w e j. D la teg o c elu p ro p o n u je się „ze sta w sp rz ęt - o p ro g ra m o w a n ie ” , k tó ry je s t re a liz o w an y z w y k o rz y sta n ie m k o m p u te ra o so b iste g o i te c h n ik m ik ro p ro c eso ro w y c h .

1. IN T R O D U C T IO N

A ccording to th e M anual fo r m ain ten an ce o f devices o f the signal system , centralization and block sy stem s it is n e cessary to check its w o rk p erio d ically w ith th e h elp o f system

"Control", p lace d in a cars - lab o rato ries, that allow ed to m easure p aram eters o f autom atical locomotive sig n alizatio n code cu rren t [1], T his system is intended for m easu rem en t o f a code current by freq u en cy 25, 50 and 75 H z, definition o f its tim e and am p litu d e param eters, calculation o f co o rd in ate o f a rail circuit (R C ), control isolate connection o f rails an d sp eed o f movement o f the ro llin g -sto ck .

M easurem ent o f co d e cu rren t sh ould be reliab ility and w h en ev er p o ssib le exclude o f labour-consum ing, lo n g on tim e and deals w ith w alk to the field operation. T h at it is impossible to carry o u t at a m anual control p aram eters o f current. B esides th e realizatio n o f measurements on ra ilw a y section deal w ith th e n ecessity o f sever o b serv an ce o f th e safety precautions reg u latio n s.

1 Automatics and T e le c o m m u n ic a tio n D e p artm e n t, D n e p ro p e tro v sk T e c h n ic al S tate U n iv e rsity o f R ailw ay Transport, A k ad . L a z a ry a n a 2 ,4 9 0 1 0 D n ep ro p e tro v sk , U kraine

! Automatics an d T e le c o m m u n ic a tio n D e p artm e n t, D n ep ro p e tro v sk T e c h n ic al S tate U n iv e rsity o f R a ilw a y Transport, A k ad . L a z a ry a n a 2 ,4 9 0 1 0 D n e p ro p e tro v sk , U k rain e, serd u ch e c k _ t@ fro m ru .c o m

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128 V lad im ir I. G A V R1LY U K , T aty an a N. SERD Y U K

T he ch eck w ith the h elp o f car - lab o rato ry allow s us to d eterm in e first o f all deviations in ad ju stm en t o f R C an d co d e eq u ip m en t, b u t d o n ’t gives p o ssib ility to m easu re p h ase o f code currents o f station R C , v alu e o f return tractiv e current in rails and sp ectru m o f interferences, asy m m etry code an d tra c tiv e c u rren ts. A s fo r th e n u m erical p aram eters o f co d e signals it is d efin ed w ith th e e rro r ± 1 0 % .

So it is n e c e ss a ry to create m easu rin g system for the ch eck o f p a ram eters o f code signals in rail c irc u it w ith m o re a ccu racy an d allo w in g to e x p a n d n u m b e r o f checking p aram eters an d to create e lec tro n ic b ases o f the m easu red an d d esig n ed data. It w ill promote m ore co m p lete a n d a u th e n tic an aly sis o f serv iceab ility o f rail circuits.

2. T H E M A T H E M A T IC A L D E S C R IP T IO N T R A N S F E R P R O C E S S E S O F T H E IN F O R M A T IO N IN T O L O C O M O T IV E ’S C O IL S

In the sy stem au to m atic lo co m o tiv e sig n allin g system (A L S ) th ere is a continuous c o m m u n icatio n b etw een track an d lo co m o tiv e devices. T h e A L S in d u cto rs C l an d C2 are situated b efo re th e first w heel p a ir o f locom otive. C oils C l an d C 2 co n n ects ind u ctiv ely , by m eans o f a m a g n e tic field , series an d to w ard s each other. M agnetic field is fo rm ed around of rails R1 and R2 b y an altern atin g code current. T hus, w ithin th e lim its o f each rail circuit (R C ) there is a sep arate channel o f co m m u n icatio n . T he circu it o f tra n sfe r o f the information fo r one R C is show n in a Fig. 1.

Fig. 1. T h e c irc u it o f tra n s fe r o f th e in fo rm a tio n o n a rail c irc u it to th e lo c o m o tiv e ’s re c e p to rs

O n the o u tp u t o f a rail c irc u it the tra n sm itte r T o f code signals is p laced . Rail circuit shunts b y first w heel p a ir W P o f lo co m o tiv e in the end. T h e cu rren t Ip in the channel of c o m m u n icatio n fo rm ed b y rails R1 an d R 2 an d w heel p air W P flow s u n d er each o f coils opposite. T h en , total in d u c e d ele c tro m o tiv e force is equal

E = E i + E2 (1)

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To the question a b o u t ch eck in g p aram eters o f code current o f rail circuit 129

w here - elec tro m o tiv e force, in d u ced in coils C l and C 2 accordingly.

Let's co n sid er th e p roblem on radiation o f electrom agnetic e n erg y by an elem en t o f a current. Let's rep lace a rail b y an equ iv alen t ro u n d co n d u cto r o f in fin ite length. T h e code current o f the sine w av e form follow s in it. Let positive direction o f a current in a rail coincides w ith a d irection o f an axis z.

For d efinition o f a m ag n etic induction and m agnetic flow ru n n in g th ro u g h coils o f A LS, we shall tak e ad v an ta g e o f v e c to r potential o f a m agnetic field A . T he d irection o f this vector coincides w ith a d irectio n o f cu rren t in conductor. V ector - potential has the follow ing connection w ith a m a g n e tic induction an d m agnetic flow .

B = rot A (2)

0 = \ B d S = \ r o t ~ A d S = § A d l (3)

w h e r e - B v ecto r o f a m ag n etic induction, T;

S - area o f a su rface, cro ssed b y a m agnetic flow , m 2;

<t> - m ag n etic flow , T m 2.

T he size an d d irection o f v ecto r potential o f a m agnetic field d e p en d on current flowing in co n d u cto rs o f length d l an d on th e Poisson equation is equal

- u - u - i - d l

A = ? D (4)

4 - K - R

w here - |i m ag n etic p e rm e a b ility o f enviro n m en t (steel o f the core), H /m ; p 0 - m ag n etic co n stan t, H /m ;

R - d istan ce from a rad iatin g co n d u cto r up to a p o in t in space, m.

In altern ativ e m ag n etic field in view o f effect o f delay o f a w ave, w hich is show n at transfer o f a signal on hig h freq u en cies (fo r exam ple, in case w ith tonal rail circu its o r high frequency in terfe ren ces) shall w rite dow n vector - potential as

J W ( t ) _

4 ■ ji • R ' ’

w here v - sp eed o f sp read in g w ave, m /s.

For d efinition o f a v e c to r o f a m agnetic induction w e to o k ad v an tag e o f cylindrical system o f coordinates. L e t’s w rite th is dependence in the com plex form . G en erally it looks like

¿ = r o t A = r 0 . ( ^ - ^ . ) + ^ 0 . ( M L _ M l ) + z ° . ( ^ a ) _ 5 A 1 ) (6)

rckx

dr ’ dz dr dr rda

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130 V lad im ir I. G A V R IL Y U K , T aty an a N. SE R D Y U K

3R y

A s v e c to r - p o ten tial has o n ly co m p o n en t A z an d — = — = sin 0 , that

gr R

B = - a 3 A Z _ d A z gR p - Pq ■ l md 1- sin 6

gr gR gr 4-7:

R R

1 -j w (t— ) j. w —j w (t )

e v + - e

R R v (7)

w here r - p ro jectio n o f a piece R on a p lan e z.

F or an in d efin itely lo n g c o n d u cto r (rail line), induction o f a m ag n etic field in a p o in t on d istance R from ra d ia to r (an d r = R ,)

R F o 1

B (t) = 2 ■7t

. . w • R sin (w ■ t )

v w . w • R

H C0S(W ■ t --- )

V V (8)

A cco rd in g to th e law o f an elec tro m ag n etic induction elec tro m o tiv e fo rce in d u ced in the A LS coils is equal

£ (f ) = - W . - d 0 A ' Ao '

d t 2 -it 4

w here Wb - num ber o f w inds o f the coil.

w-R. w . , w-R^ w cos(w • t ) --- sin(w • t --- ) ---

v R v v (9)

T he re su lts o f m o d e llin g o f virtual value o f electro m o tiv e force on the d istan ce R from the so u rce o f rad iatio n (rails) fo r ex istin g rail circuits in U kraine b y low fre q u e n c ie s (25, 50 and 75 H z) are given b elo w (F ig.2). C u rren t in the rail is equal 10 A . T h e calculation was e xecuted w ith o u t tak in g in to acco u n t o f the p h enom enon o f w ave delay , b e c a u se it has no for low frequencies. T h at is w h y eq u atio n (1 0 ) is sim pler. T he relativ e erro r betw een the m easu red an d calc u lated d ata is ± 3.5% .

E ffe c tiv e va lu e o f e le c tro m o tiv e fo rc e on th e d is ta n c e R fro m ra il f o r d if fe r e n t s ig n a l fre q u e n c ie s

M easured data (f=75 Hz)

A Measured data (f=25 Hz)

53 Measured data (f=50 Hz)

□ s t a n c e R, sm -C alcu lated data (f=75 Hz)

Calculated data (f=25 Hz)

— - - Calculated data (f=50 Hz)

F ig .2 . E lec tro m o tiv e fo rc e on th e d is ta n c e R fro m rail a t the c o d e c u rre n t b y v a lu e o f 10 A

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To the question ab o u t ch eck in g param eters o f code current o f rail circu it 131

So w e h ave equation o f electro m o tiv e force induced in th e coils o f A L S , w hich is allowed to tak e into acco u n t effect o f delay o f a w ave in case w ith tonal rail circu its o r high frequency in terferen ces. T he depen d en ce betw een code current and elec tro m o tiv e fo rce in inductors is received. T h is w ill be used at the definition o f param eters o f code cu rren t w ith the help o f the device, at w hich the d etec to r o f the inform ation are locom otive coils.

3. T H E H A R D W A R E O F A M E A S U R IN G C O M P L E X

For definition o f num erical and tim e param eters o f signal cu rren t the h ard w are-so ftw are measuring co m p lex is o ffered, w hich b lo ck diagram is given in a F ig.3.

This is re alized as a additional d evice to the personal co m p u ter (P C ) such as IBM PC . It carries out digital p ro cessin g o f analog signal from the locom otive coils and contains the following b asic units: the b lo ck o f com m utator, dividers, lim iting am plifiers, analog-digital converter (A D C ), m u ltip lex ers, g en erato r o f tact im pulse, program tim er, control device (registers o f the d ata an d operate).

Dgital input "

Signal fir m ALSooils

Logical

anal>sis

Block of conmiator

D v id er 1:10

D v id er 1:100

Amplifier K=10

data C p tro n 's Limiting

amplifier

A D C

*- block

Run

Control device

Ready of data

Program tim er

Multi­

plexers

IB M P C

GTI

F ig .3 . S tru ctu re sch e m e o f d e v ic e fo r th e ch ec k in g o f c o d e c u n 'e n t p a ra m e ters

T en-digit A D C o f serial approach has in p u t ran g e ± 5V and w ill tran sfo rm an analog signal to a digital code w ith a step o f quantization ±5m V . T he m axim al A D C d iscretization frequency is 40 k H z th a t it is q u ite enough for realization o f the spectral analysis o f a current flowing in rails. T he differential erro r m akes n o m ore than 0,1 % . A lso th ere is p o ssib ility to use tw elve-digit A D C .

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132 V lad im ir 1. G A V R 1L Y U K , T aty an a N. S E R D Y U K T he p ro g ra m m e d tim e r is in ten d ed fo r the definition o f d iscretizatio n freq u en cy o f input signal. T he interval o f d iscretizatio n can be ch an g ed in w ide ran g e from 25 m icro sec o n d s up to 70 m in u te (b o tto m lim it o f dicretizatio n frequency is lim ited to p ro p ertie s o f A D C , an d top - tim e r and d iv id e r o f freq u en cy ). T h e program tim er p roduces the freq u en cy o f sig n als. They is stab ilized b y th e q u artz re s o n a to r on 1 M H z.

T h e control d ev ice c o n sists o f the reg isters o f the data an d o p eratio n , w h ich are n ecessary fo r th e task o f o p eratio n s o f the p ro g ram tim er, m u ltip lex ers and also block of com m utator.

T he b lo ck o f c o m m u ta to r is n eed ed fo r a d ep en d en ce o f a voltage ran g e o f in p u t analog signal. It co n sists o f a so m e sm all-sized relay s, tran sm ittin g a signal on the lim itin g am plifier o r th ro u g h a d iv id e r (1 :1 0 an d 1:100). It is allo w ed to in crease an in p u t d iapason o f v o ltag e up to 500V . T h u s, th e g iv e n d ev ice can be u sed for reco rd in g a signal n o t o n ly from inductive coils o f A L S , an d from o th e r d etec to rs n o t situ ated on the loco m o tiv e, and co n n ected to a rail circuit, feed er o f return tractiv e cu rren t (fo r the am p litu d e and spectral an aly sis o f interference flow ing in rail circu its). A lso in p u t signal can be am p lified w ith the h elp o f th e operational am p lifier in 10 tim es. T h at is n e cessary fo r reco rd in g signals from coils a u to m atic locom otive signal system in a ran g e from 0 up to 500 m V . T hat exp an d s area o f ap p licatio n o f th e given device.

T he lim itin g a m p lifie r is in ten d ed fo r restrictio n o f an A D C in p u t from v o ltag e at a level 5,5 V. It p ro v id es hig h in p u t resistan ce o f a h ard w are-so ftw are com plex to p rev en t influence o f m easu rin g system on w o rk devices o f au to m atics an d telem ech an ics.

T he o p tro n ’s b lo ck is n e c e ssa ry fo r in crease p ro tect from in terfe ren ce a n d re liab ility of w o rk o f m easu rin g system . It p ro v id es g alv an ic division betw een an alo g an d digital parts.

T h ere is p u lse in te rfe re n c e in rail circu it som etim es. A t the use g alv an ic d iv isio n th e failure take p lace on ly in A D C circu its th a t is som e choices o f data w ill h av e lim itin g v alu e 5,5B.

A fter d is ap p earan ce o f a in terfe ren ce th e d ev ice w ill begin to w o rk in a norm al m o d e, and the arisen o f its is tra c e d b y p rogram .

T he m e a su rin g d ev ice co n n ects to th e PC th ro u g h p arallel p o rt (L P T ). T he block of m u ltip lex ers has 16 in p u ts an d n eed s fo r the conform ation o f A D C w ith th e L P T -port of com puter. T h at g ives p o ssib ility to control up to 6 digital signals tra n sm ittin g on an input of the logic an aly ser sim u ltan eo u sly , w hich supervises presen ce o f a code.

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To the question a b o u t ch eck in g p aram eters o f code current o f rail circuit 133 4. A L G O R IT H M O F F U N C T IO N IN G O F D E V IC E

A lgorithm s o f p ro c e ssin g signal b y the device fo r the checking o f p aram eters o f code current on th e h ard w are an d so ftw are levels are given on a Fig.4.

F ig .4 . A lg o rith m s o f p ro c e ssin g o f a sig n al at a h a rd w a re and so ftw a re levels

The d iscretizatio n freq u en cy o f in p u t signal records in the program tim e r b efo re the beginning o f p ro cessin g o f a signal. T he p ro g ram tim er gives com m and “ start-up o f signal transform ation” . It d ev elo p s w ith th e given interval. O n ending tran sfo rm atio n A D C gives out a com m and “read in ess o f d a ta ” , th a t causes h ard w are interruption o f L PT port o f com puter.

The subprogram o f pro c e ssin g o f interruption carries out read in g th e data from th e A D C into the buffer o f th e c o m p u te r’s R A M .

The digital p ro cessin g o f a signal and analysis o f th e data is carried out w ith th e help o f special p rogram . Its alg o rith m is show n on fig.4.

T he d rift c o m p en satio n o f in p u t signal allow s to exclude o f an error w h ich is b ro u g h t in by the in terface b lo ck o f th e h ard w are an d influence o f voltage o f d isp lacem en t o f the in p u t cascade o f a m e asu rin g co m p lex (operational am plifier and A D C ).

T he signal a v erag in g is u sed at the analysis h arm onic signals. It calculates a spectrum o f a signal n o t on one sam p le, and on several. R esult averages. I f it is n ecessary to investigate pulse interferen ce, th e av erag in g b lo ck is ex clu d ed by program .

T he p ro ced u res o f digital filtration o f signal are included in structure o f the softw are.

There is freq u en cy w ay o f filtratio n on the base o f F ast F ourier T ran sfo rm atio n . E arly th ere is analog filters. It is k now n th at th e digital filters has the follo w in g adv an tag es in front o f analog: the high stab ility o f d iscretizatio n frequency (this p ro p erty is re alized at a hardw are level and is cau sed b y th e app licatio n o f the q uartz g enerator), sim p licity o f reo rg an izatio n frequency the characteristics, p o ssib ility o f realization o f several types o f filters at once.

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134 V lad im ir I. G A V R IL Y U K , T aty an a N. S E R D Y U K T he scalin g allo w s to tra n sfe r a digital code in values o f a real signal o f controllable param eter. T h a t is n e c e ss a ry fo r ch eck o f correctness o f tran sfo rm atio n o f a signal an d for p rep aratio n o f a signal fo r th e analysis.

T he a p p ro x im atio n . F or th e p ro cessin g o f w ritten signal there is p o ssib ility to ap p ly os subp ro g ram o f lin ear o r sp lay ap p ro x im atio n fo r reception o f in term ed iate resu lts betw een sam ples. T h e lin ear ap p ro x im atio n has sm aller accuracy, but it allo w s to p ro cess the large data files w ith high sp eed an d can b e u sed fo r a ten tativ e estim ation m e a su rem en t resu lts and at the an aly sis given w ith o u t th e high req u irem en ts to accuracy. T he p recisio n d a ta can be receiv ed w ith th e h elp sp lay ap p ro x im atio n , but it requires the large c o m p u tin g opportunities.

T he g rap h ic p a rt is in te n d e d for realizatio n o f th e m an -m ach in e in terfa ce and m an ag e m en t o f p ro c e sse s o f digital p ro cessin g o f a signal, an aly sis o f the d ata and m an ag e m en t o f th e h ard w are o f a m e a su rin g co m p lex and w as d escrib ed in [2],

T he d riv e r L P T p o rt is n e c e ssa ry fo r an ex ch an g e o f th e in fo rm atio n b etw een the PC an d h ard w are o f a m e a su rin g device. U se o f th e given d riv er allow s to function to the softw are u n d er o p eratio n al sy stem s W indow s-98 o r -2000. It g iv es p o ssib ility to co n n ect the reg isters o f p arallel p o rt an d to carry out p ro cessin g hardw are in terru p tio n s actin g from ADC.

T h e h ard w a re -so ftw a re co m p lex p ro v id es executing o f th e fo llo w in g functions:

m easu rem en t an d ch eck on co n fo rm ity to th e req u irem en ts num erical an d tim e param eters of code current, d efin itio n o f the p aram eters o f rail circu its an d asy m m etry o f code and tractive current in rails (at the re c o rd in g o f signals from A LS coils sep arately ), calc u latio n of am p litu d e- an d p h a se -fre q u e n c y ch aracteristics o f code and tractiv e cu rren t, sav in g up to 10 m illio n sam ples, p ro b a b ility an d statistic p ro cessin g o f m easu rem en t signal, d istrib u tio n o f the reco m m en d atio n s co n c e rn in g a d ev iatio n o f code signal from n o rm s an d as fo r their elim ination.

5. M E A S U R E M E N T S

T he given m e a su rin g d ev ice allo w s to reco rd a signal from an o u tp u t(ex it) o f th e filter, as it is req u ire d th e m a in te n a n c e M anual o f devices o f th e signal system , cen tralizatio n and b lo ck the ch eck o f w o rk o f dev ices au to m atic lo co m o tiv e sig n allin g sy stem (A L S ), an d as lo co m o tiv e coils. R esu lts o f m easu rem en t: view code signal o f ty p e “ g reen ” in m o d e of o scillo sco p e an d th e ir sp ectru m an aly se is given on a Fig.5. T h is signal w as re c o rd from the lo co m o tiv e coils on th e ra ilw a y section o f d irect cu rren t n ear tractive su b statio n . D eviation in the num erical an d tim e p aram eters o f code cu rren t w as n o t detected. B ut you can see high level o f in terfe ren ces in the return tractiv e cu rren t b y freq u en cy o f 600, 1200, 1800 and 2400H z, w hich are c a u se d b y the w o rk o f 12-pulse rectifier.

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To the question a b o u t ch eck in g p aram eters o f code current o f rail circuit 135

V ie w p f sig n a l near tra ctive su bsta tion

mu Mnw m ti»

1 1 . 5

A x e s o f tim e ,s e c o n d

Spectrum o f signal

0 .0 4

« 0 0 3

o 0.02 -<>-■

“i

1 5 0 0

Frequency ,Hz

J L

F ig .5. R esu lts o f m e a su re m e n t: v ie w c o d e signal o f ty p e “ g re e n ” in m o d e o f o sc illo sc o p e and th e ir sp ec tru m a n aly se

6. C O N C L U S IO N S

T he h ard w are-so ftw are co m p lex fo r the check o f param eters o f a code cu rren t in rails is developed. T he given d ev ice is m u ltifu n ctio n al, as allow s n o t on ly to d efine p aram eters o f currents and rail circu its, an d to carry out the analysis o f an elec tro m ag n etic situation on the given railw ay section an d also to d eterm in e a spectrum o f in terferen ces flo w in g in a rail circuit. T he m easu rem en ts can be realise d on the basis o f w o rk in g cars - lab o rato ry , by recording a signal from recep tio n co ils, an d on railw ay section at connection o f the eq u ip m en t to a rail circuit o r feed er o f retu rn tractiv e current.

B IB L IO G R A P H Y

[1] M ain ten an ce M an u al O f D e v ice s O f T h e S ignal S y stem , C e n tra liza tio n A n d B lo c k , M o sco w : T ran sp o rt, 1999.

[2] G A V R IL Y U K B .I., S E R D Y U K T .N ., T e le m e tric S y stem F o r T h e C o n tro l O f S ignal P a ra m e te rs O f Rail C ircuits, T S T 2 0 0 2 , T ra n s p o rt S y stem s T e le m a tic s, K a to w ice -U stro n , 200 2 .

[3] O L S O N G ., P IA N I G ., D ig ital S y ste m s o f A u to m a tisatio n and O p e ra tio n , S a n k t-P etersb u rg , 20 0 1 .

R eview er: Ph. D. A ndrzej B iałoń

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