ES Paper

B.M.A.S ENGINEERING COLLEGE,AGRA(Pre-University Exam.)

Branch - EC Time-03 HrsPaper Code - TEC-702 Subject- Electronic SwitchingSem. - 7TH Max. Marks - 100Note: (1) Attempt all questions

(2) All questions carry equal marks______________________________________________________________________________

Q1 (a) During the busy hour a group of trunks is offered 100 calls having an average durationof 3 minutes. One of the calls fails to find a disengaged trunk. Find (i) the traffic offered to the

roup (ii)traffic carried by the group (iii) GOS.

(b) A group of 20 circuits was found to have 10 circuita engaged at 10 a.m.,15 at 10.10 a.m., 16 at 10.20 a.m. and 11 at 10.30 a.m. Calculate the traffic intensity during this period.

Q2 10 E of traffic is offered to switches that hunt sequenttially over a group of trunks. Estimate the traffic carried by each of the first three trunks.

Q3 On average, one call arrives every 5 seconds. During a period of 10 seconds, what is the probability that: (i) No call arrives? (ii) One call arrives? (iii) two calls arrives? (iv) More than two calls arrives?

Q4 Define grade of service for any exchange. What does a higher value of GOS signify? Differentiate between GOS and blocking probability.

Q5 What is the renewal process or pure birth process. Find out the equation which governs the dynamics of renewal process.

Q6 Write short notes for any three

(i) Define three busy hour recommended by CCITT.

(ii) Call Completion Rate (CCR)

(iii) Busy Hour Calling Rate (BHCA)

(iv) Traffic Intensity

(v) Day – to – busy hour traffic ratio.

(vi) State transition diagram for local call

Q7 Briefly describe the various modes of operation in dual processor architecture.

Q8 What do you meant by distributed stored program control ? Describe three level processing of distributed SPC

Date of Exam. Roll No.

B.M.A.S ENGINEERING COLLEGE, AGRA(II sassional Test.)

Branch - EC Time-90 Min.Paper Code - TEC-043 Subject- Optical NetworksSem. -8TH Max. Marks - 30Note: (1) Attempt Five questions

(2) All questions carry equal marks

Q1. (a) Explain the principle of operation of Isolator and circulators.(b) Explain the working and construction of a fused biconical tapered coupler.

Q2. (a) Explain the working principle of MZI multiplexer. Construct a four channel wavelength multiplexer using 2 x 2 MZI elements.

(b) Compare the Fabry Perot wavelength demultiplex with grating base filter.

Q3. (a) Mention the advantages offered by optical amplifiers over regenerators. Explain the principle of operation of EDFA.

(b) What is crosstalk. Explain how it can be reduced in semiconductor optical Amplifiers.

Q4. (a) What is wavelength converter? Mention the types and explain any one.(b) What are the characteristics of laser as a light source in WDM? Explain

distributed feedback (DFB) lasers.

Q5. (a) What are the important parameters used to characterized the suitability of a switch(b) Explain the Micro-Electro-Mechanical system (MEMS) switch.

Q6. Name any four networks that acts as clients layer of the optical layer. Explain the basic structure of the STS-N frame and hence deduce the bit rate of STS-1 signal.Explain any two factors that led to evolution and standardization of SONET/SDH.

Q7. What is ATM standard? Explain various fields of header structure of an ATM cell across user to network interface.

Q8. (a) Explain about OADM architecture.(b) Differentiate between routing and forwarding in IP protocol.

Q9. Write short note(a) Spanke benes switches(b) braggs grating(c) functional block diagram of SONET/SDH system(d) principle of operation of RAMAN AMPLIFIERS


B.M.A.S. ENGINEERING COLLEGE, AGRA(Improvement test)

Branch - EC Time- 90 Min.Paper Code - TEC-043 Subject- Optical NetworksSem. -8TH Max. Marks - 30Note: (1) Attempt Five questions


Q1 (a) Explain significance of optical layer.(b) What do you mean by transparency(c) Define the term refractive index.

Q2 (a) What do mean by non linearities in optical fibers(b) Explain Kerr Effect in detail(c) How is non linearities reduced in optical networks

Q3 (a) Why FWM is so important in today’s optical network?(b) Discuss different methods of Clock Exchange.(c) What do you mean timing down stream devices.

Q4 (a) What are three functional types of optical amplifier? Why is erbium used in EDFA?

(b) What phenomenon determines the bandwidth of an EDFA(c) Write a short note on Cross bar Switches

Q5 (a) Explain the function & the Principle of operation of Wavelength Converters? (b) Differentiate between strict sence and wide sense non blocking switches(c) Explain Optical cross-connect ?

Q6 (a) Give detail description of acoustic amplifier(b) Explain about the parameters used to characterised the suitability of a switch for

optical networking.(c) Discuss the working of tunable lasers

Q7 (a) Explain the concept of Buffering(b) Explain about burst switching(c) What do you mean by header processing.

Q8 (a) Describe the optical layer service termed “establishing light path” and “establishing virtual circuits”

(b) Explain the functions of Media access control protocols.(c) Define OTDM?


B.M.A.S. ENGINEERING COLLEGE, AGRA(PUT)

Branch – EC1 & EC2 Time- 3Hrs.Paper Code - TEC-043 Subject- Optical NetworksSem. -8TH Max. Marks – 100 Note: (1) Attempt all questions


Q1. Attempt any four parts of following.

(a) What are the two category of non-linear effects. Differentiate SBS and SRS.(b) What are solitons ? How they are capable of reducing non-linear effects ? Explain.(c) What is Kerr effect. Explain self phase and cross phase modulation.(d) Explain the structure and properties of DFB laser.(e) Write the short note on timing and synchronization in optical networks.(f) What is the optical networks. Draw a block diagram and explain the key elements

of optical communication system.


(a) Explain the working principle of MZI multiplexer. Construct a four channel wavelength multiplexer using 2 x 2 MZI elements.

(b) What are three functional types of optical amplifier? Why is erbium used in EDFA? What phenomenon determines the bandwidth of an EDFA.( c) Explain the working and construction of a fused biconical tapered coupler. A 2 x 2

biconical tapered fiber coupler has input power level of P0 = 200 W. the output power at other three ports are : P1 = 90 µW, P2 = 85 µW, P3 = 6.3 nW. Calculate splitting ratio, excess loss, insertion loss and cross talk

(d) Compare the Fabry Perot wavelength demultiplex with grating base filter.(e) What is wavelength converters? Mention the type explain any one.(f) Explain why isolator is called passive non-reciprocal device. Explain its principle of Operation.

Q3. Attempt any two parts of following.(a) Name any four networks that acts as clients layer of the optical layer. Explain the

basic structure of the STS-N frame and hence deduce the bit rate of STS-1 signal.Explain any two factors that led to evolution and standardization of SONET/SDH.

(b) What is ATM standard? Explain various fields of header structure of an ATM cell across user to network interface. (c) How WDM is different from FDM. Explain the key features of WDM system?

What are different OADM architectures. Explain any one with proper diagram.


(a) Differetiate between lightpath topology design (LTD) problem and routing wavelength assignment (RWA) problem. For a point to point WDM (PWDM) ring design topology calculate design parameters required in determining minimum cost.

(b) Why SONET/SDH are called self healing. Explain the protection technique implemented in SONET/SDH rings.

(c) Differentiate between IP networks and SONET/SDH networks.(d) Discuss different protection Schemes in SONET/SDH.(e) Discuss in detail about different types of optical n/w elements.(f) Discuss re-confugrability in OADM?


(a) What are the advantages of wavelength routed network?(b) Why do we need Optical Cross Connect (OCC)?

(c) Explain the concept of Buffering(d) Explain about burst switching(e) What do you mean by header processing.(f) What are the different ways deployed for increasing transmission capacity of transmission layer in optical networks. Explain architectural choice for generation transport networks.

.

Assignment # 1 date of submission 16/09/2011

Q1 Explain general optical communication diagram. Mention the advantages & disadvantages of optical fiber as waveguide over conventional metallic waveguide? Q2 Using ray theory describe the mechanism for transmission of light with in an optical fiber Briefly discuss with the aid of suitable diagram what is meant by the accept angle for an optical fiber show how it is related to the numerical aperture and refractive indices for core and cladding.Q3 What is meridional and skew rays ? how does rays propagate inside an optical fiber.Q4 What is the function of core and cladding in optical fiber. Why should their refractive indices be different .Q5 Consider a parabolic index waveguide with n1=1.75,n2=1.677 and core radius 52μm Calculate the numerical aperture at the axis and at a point 20μm from the axis.Q6 Compare SM fiber and Graded index fiber. Explain the requirements for fiber materials?Q7 A fiber has normalized frequency is 26.6 and wavelength is 1300nm.If the radius of core is 25μm.Compute numerical aperture?Q8 What are Fiber modes? Explain mode theory for optical fiber in detail?Q9 A multimode step index fiber with core diameter of 80μm and index difference of 1.5% at wavelength of 0.85μm.If the refractive is 1.48,find normalized frequency and no of modes?Q10 What is meant by modes of waveguide? Define V number? What is relation between V number and power flow in cladding?Q11 The relative index difference in graded index fiber is 0.7% ,core refractive is 1.45. Find numerical aperture when index profile is triangular. Q12 write Short notes on (a) cut-off wavelength (b) Mode field diameter ( c) effective wavelengthQ13 Drive an expression for the acceptance angle for a skew rays which changes direction By an angle 2Ỵ (Gama) at each reflection in step index fiber in terms of NA and Ỵ Q14 what are the material requirements for optical fiber? Discuss the different optical fibers on the basis of material used.Q15 What are the fiber fabrication techniques. Describe all in briefQ16 A 45° – 45° - 90° prism is immersed in alcohol ( n = 1.45) what is the minimum refractive Index the prism must have if a ray incident normally on one of the short face is to be totally reflected at the long face of the prism.Q17

Q18

Q19

Q20

Q21

2. Mention the three advantages of optical fiber as waveguide over conventional

metallic waveguide?3. What is meant by mode and index profile?4. Mention the advantages of Graded Index fiber.5. Write the expression for the refractive index in Graded index fiber.6. Define Numerical Aperture of step index fiber.7. Give the expression of the effective number of modes that are guided by a curvedmultimode fiber of radius ‘ a’.8. State Snells Law.9. Define Critical angle?10. Define TIR?11. What is the need of Cladding?12. Define core index difference.13. Define refractive index?14. What are leaky modes in optical fibers?15. Define External reflection of light rays?16

17. 18. 19. What is the fundamental parameter of SM fiber?20. Give the relation between rays and modes?21. What are the advantages and disadvantages of SM fiber?22. What are the advantages and disadvantages of MM fiber?23. Define skew rays and merdional rays?24. Define cutoff conditions?25. What is meant by Degenerate modes?26. What is meant by linearly polarized modes?27. Define MFD?28. Define Bi refrigence and beat length?

30. Consider a parabolic index waveguide with n1=1.75,n2=1.677 and core radius 52μm.Calculate the numerical aperture at the axis and at a point 20μm from the axis.31. Why do we prefer step index single mode fiber for long distance communication?32. Why do we use LP01 mode for long distance communications?33. What are three operating windows?34. Alight ray is incident from glass to air. Calculate critical angle?35 (16)36. Compare SM fiber and Graded index fiber. Explain the requirements for fibermaterials? (16)37. Discuss the theory of GI fiber. Derive the expression for the numerical aperture of GIfiber? (16)38. Derive an expression for number of modes propagating in GI fiber from the first

principle . (16)39. i) Mention the advantages of optical communication systems? (8)ii) Draw the elements of an optical communication systems?40. i) Discuss the propagation modes in SM fiber (8)ii)Briefly explain the evolution of fiber optic systems? (8)41. i)Compare the configurations of different types of fibers? (8)ii) Discuss the modes in Step index fiber? (8)42. i)Derive the wave equations for step index fiber and explain? (8)ii)Sketch and explain the electric field distributions of low order guided modes insymmetrical slab waveguide? (8)43 (16)44. a)

(8)b) Derive the expression for power flow in step index fiber? (8)45. a)Explain Linearly polarized modes? (8)b) (8)46 a).Derive modal equation. b) Compare single and multimode fiber.

HINDUSTAN INSTITUTE OF TECHNOLOGY& MANAGEMENT(I Sassional Test.)

Branch - EC Time- 90 Min.Paper Code - EEC-701 Subject- Optical CommunicationSem. - 7TH Max. Marks - 30Note: (1) Attempt five questions


Q1 Explain general optical communication diagram. Mention the advantages & disadvantages of single mode step index & graded index optical fiber .

Q2 What is meridional and skew rays ? Drive an expression for the acceptance angle for a skew rays which changes direction By an angle 2Ỵ (Gama) at each reflection in step index fiber in terms of NA and Ỵ

Q3 What are Fiber modes? Explain mode theory for optical fiber in detail?

Q4 Consider a parabolic index waveguide with n1=1.75, n2=1.677 and core radius 52μm calculate the numerical aperture at the axis and at a point 20μm from the axis also acceptance angle.

Q5 A point source of light is 12 cm below the surface of large body of water ( n = 1.33 for water). What is the radius of large circle on the water surface through which light can emerge.

Q6 What are Fiber modes? Explain mode theory for optical fiber in detail?

Q7 What are the material requirements for optical fiber? What are the fabrication technique. Explain modified chemical vapor deposition technique.

Q8. Find the core radius necessary for single mode operation at 1320 nm of step index fiber with n1 = 1.48 & n2 = 1.478. What is the NA and maximum acceptance angle of this fiber.

HINDUSTAN INSTITUTE OF TECHNOLOGY& MANAGEMENT(I Sassional Test.)

Branch - EC Time- 90 Min.Paper Code - EEC-701 Subject- Optical CommunicationSem. - 7TH Max. Marks - 30Note: (1) Attempt five questions


Q1 Explain general optical communication diagram. Mention the advantages & disadvantages of optical fiber as waveguide over conventional metallic waveguide?

Q2 Compare SM fiber and Graded index fiber. Explain the requirements for fiber materials?

A 45° – 45° - 90° prism is immersed in alcohol ( n = 1.45) what is the minimum refractive Index the prism must have if a ray incident normally on one of the short face is to be totally reflected at the long face of the prism.

Q What are the fiber fabrication techniques. Describe all in brief

Q A step index fiber has a solid acceptance angle in air of .115 radian and a relative refractive index difference of 0.9%. estimate the speed of light on the fiber core.

Q A single mode step index fiber has core and cladding refractive indices of 1.498 and 1.495 respectively. Determine core diameter for fiber to permit its operation over the wavelength range 1.48 to 1.6 µm . calculate the new fiber core diameter to enable single mode transmission at a wavelength of 1.3 µm.

HINDUSTAN INSTITUTE OF TECHNOLOGY& MANAGEMENT(II Sassional Test.)

Branch - EC Time- 2 Hrs.Paper Code - EEC-701 Subject- Optical CommunicationSem. - 7TH Max. Marks - 60Note: (1) Attempt five questions


Q1 (a) List the basic attenuation mechanisms in an optical fiber.

(b) A optical signal at a specific wavelength has lost 55 percent of its power after travelling 7.0 km of fiber. What is the attenuation in dB/km of this fiber.

Q2 (a) Discuss the absorption losses in optical fiber , comparing and contrasting the intrinsic and extrinsic absorption mechanisms.

(b ) A continuous 40 – km - long optical fiber link has loss of 0.4 dB/km(i) What is the minimum optical power level that must be launched in to the fiber to

maintain an power level of 2.0 µW at the receiving end.(ii) What is the required input power if fiber has a loss of 0.6 dB/km.

Q3 (a) compare stimulated Brilliouin and stimulated Raman scattering in optical fibers and indicate the way in which they may be avoided in optical fiber communication.

(b ) the threshold optical power for stimulated Brilliouin scattering at a wavelength of 0.85 µm in a long single mode fiber using an injection laser source with a bandwidth of 800 MHz is 127 mW. The fiber attenuation of 2 dB/km. Determine the threshold optical power for stimulated Raman scattering with in the fiber at a wavelength of 0.9 µm assuming the fiber attenuation is reduced to 1.8 dB/km at this wavelength.

Q4 (a) Briefly describe linear scattering losses an optical fibers with regard to;

(i) Rayleigh scattering (ii) Mie scattering

(b ) the photo elastic coefficient and the refractive index of silics are 0.286 and 1.46 respectively. Silica has isothermal compressibility of 7 x 10 -11 m2 N-1 and an estimated fictive temperature of 1400 K. Determine the theoretical attenuation in desible /km due to fundamental Rayleigh scattering in silica at optical wavelength of 0.85 and 1.55 µm. Boltzmanns constant is 1.381 x 10-23 J K-1 .

Q5 (a) Briefly explain the reason s for pulse broadening due to material dispersion in optical fiber. Derive an expression for the rms pulse broadening due to material dispersion in an optical fiber and define the material dispersion parameter.

(b ) the material dispersion parameter for a glass fiber 20 ps nm-1 km-1 at a wavelength of 1.5 µm. Estimate pulse broadening due to material dispersion with in the fiber when light is launched from an injection laser source with the peak wavelength of 1.5 µm and an rms spectral width of 2 nm into a 30 km length of fiber.

Q6 (a) Describe the mechanism of intermodal dispersion in a multimode step index fiber. Show that the total broadening of light pulse δTs due to intermodal dispersion in a multimode step index fiber may be given by;

δTs ≈ L (NA)2 /2n1 c

(b ) A multimode step index fiber has a numerical aperture of 0.2 and core refractive index of 1.47. Estimate the bandwidth – length product for the fiber assuming only intermodal dispersion and return to zero code when;

(i) There is no mode coupling coupling between the guided modes;

(ii) Mode coupling between the guided mode gives a characteristic length equivalent to 0.6 of actual fiber length.

Q7 (a) What are attenuation measurement techniques. Explain insertion loss technique .

(b ) What are the measurements can be taken by OTDR. Explain the function of OTDR

(c ) What are the dispersion measurement technique . Explain chromatic dispersion measurement technique.

Q8 (a) State two major categories of fiber – fiber joint ; including the differences between them . A Fresnel reflection at the butt joint wit an air gap in a multimode step index fiber is0.46 dB. Determine the refractive index of the fiber core.

(b ) Describe what is meant by fusion splice of optical fiber. Discuss the advantage and drawbacks of this technique .

(c ) A multimode step index fiber with core refractive index of 1.52 is fusion spliced. The splice exhibits an insertion loss of 0.8 dB. This insertion loss is found to be entirely due to angular misalignment of the core axes which is 7˚ . Determine the numerical aperture of the fiber.

TUTORIAL – 1 (UNIT-2)

HINDUSTAN INSTITUTE OF TECHNOLOGY& MANAGEMENT(Pre-University Test.)

Branch - EC Time- 3 Hrs.Paper Code - EEC-701 Subject- Optical CommunicationSem. - 7TH Max. Marks – 100

Note: (1) Attempt four questions. Question 3,4,5 are compulsory. (2) All questions carry equal marks

Q1. Attend any four of the following :

(a) Define the term Numerical Aperture (NA) of the fiber. On what factor does it dependents ? How can it be maximized ? Explain. (6)

(b) The speed of light in vacuum and that in the core of the fiber is 3 x 108 ms-1 and 2 x 108 ms-1 respectively. When the fiber is placed in air, critical angle at the core cladding interface is 750. Calculate(i) the NA of fiber and (ii) multipath dispersion per unit length.

(6) (c) Multimode step index fiber has a relative refractive index difference of 1% and the core

refractive index of 1.5. The number of modes propagating at a wave length of 1.3µm is 1100. Estimate the diameter of fiber core. (7)

(d) Define an optical fiber, explain different type of optical fibers giving neat sketches. (6)(e) List the requirements that be satisfied by materials to used manufacture optical fiber. Write types of optical fiber and explain in details of PCF. (6)(f) What are the fabrication techniques. Explain modified chemical vapor deposition technique. (6)

Q2 Attend any four of the following :

(a) What are the basic attenuation mechanisms in the optical fiber communication? Explain in brief on what factors this mechanism depends? (6)

(b) Briefly explain the reasons for pulse broadening due to material dispersion in optical fibers. The group delay τg in an optical fiber is given by:

τg = where is the velocity of light in vacuum, n1 is the core refractive index and λ is the wavelength of the transmitted light . Derive the expression for the rms pulse broadening due to material dispersion in an optical fiber and define the material dispersion parameter. (6)

(c) Describe the mechanism of intermodal dispersion in a multimode step index fiber. Show that the total broadening of light pulse δTs due to intermodal dispersion in a multimode step index fiber may be given by;

δTs ≈ L (NA)2 /2n1 c (7)( d) A glass fiber exhibits material dispersion given by | λ2 (d2n1/dλ2) | of 0.025. determine the material dispersion parameter at a wavelength of 0.85 µm, and estimate the rms pulse broadening per kilometer for a good LED source with an rms spectral width or 20 nm at this wavelength (6)

( e) Describe the techniques employed and the fiber structures utilized to provide: (6)(i) Dispersion shifted single mode fibers:(ii) Dispersion flattened single mode fibers.

( f) What is splicing ? Explain about fusion splicing. (6)


(a) Draw the schematic of edge emitting double hetero junction LED and explain its working in detail? (6)(b) Briefly outlined the general requirements for a source in optical fiber communication. Discuss the areas in

which the injection laser fulfill these requirements, and comments on any drawbacks of using this device as an optical fiber communication source. (6)

(c) Draw the schematic diagram of high radiance surface emitting LED and explain the working in detail? (6)

(d) A double hetero-junction InGaAsP LED emitting a peak wavelength of 1310 nm has radiative and nonradiative recombination times of 25 and 90 ns respectively. The drive current is 35 mA (7)

(i) Find the internal quantum efficiency and the internal power level.(ii) If the refractive index of light source material is n = 3.5, find the power emitted from the

device(e) Discuss the mechanism of optical feedback to provide oscillation and hence amplification within the laser.

Indicate how this provides a distinctive spectral output from the device (6)


(a) Explain detection process in the p-i-p photodiode, compare this device with APD photodiode. (6)(b) Describe in details the factors which limit speed of response of a photodiode. (6)(c) A p-n photodiode has a quantum efficiency of 50% at a wavelength of 0.9 µm. calculate (7)

(i) Its responsivity at 0.9 µm(ii) The received power if the mean photocurrent is 10 -6 A.(iii) The corresponding number of received photons at this wavelength

(d) List the factors involved in launching optical power from a light source to a optical fiber? Briefly explain about source output pattern in power launching from source to fiber (6)(e) Explain about laser diode-to-fiber coupling. Also explain about lensing schemes for

coupling efficiency improvement. (6)


(a) The rise times for various components of intensity modulated fiber optic link are listed below. Determine if these specifications support a 5 km repeater less fiber optic link with 6 MHz optical bandwidth.

time of LED transmitter electronics = 10 ns Inter-modal dispersion induced = 8ns/km Intra-modal dispersion induced = 2ns/km Rise time of Detector and receiver electronics = 3ns (7)

(b) What are the underlying principles of the WDM technique? What are its various advantages? How is it different from FDM technique? (6)( c) Describe with suitable diagram, for measurement of fiber attenuation using cutback technique? (6)(d) Discuss system considerations in point-to-point optical link. Give an account of fiber optic link power budget with an example. (6)(e) Explain the working of OTDR. What are the tasks can be performed by OTDR. (6)

HINDUSTAN INSTITUTE OF TECHNOLOGY& MANAGEMENT(Pre-University Test.)

Branch - EC Time- 3 Hrs.Paper Code - EEC-802 Subject- Electronic SwitcingSem. - 8TH Max. Marks – 100

Note: (1) Attempt four questions. Question 3,4,5 are compulsory. (2) All questions carry equal marks

Q1 Attempts any four parts of the following questions:

(a) Give the classification of switching systems. Compare manual exchange and automatic exchange. (6)(b) Draw the general trunking diagram for a switching system and explain the principle of reed relay. (6) (c) With the help of suitable diagram describe the working of a crossbar exchange. (6)(d) Explain the blocking and non-blocking model of telephone traffic. (6)


(a) With the help of neat diagram explain the operation of TSI. Compare the TSI with space switching.(6)(b) How many TSI modules are needed for STS switch with 128 primary TDM signals of 30 channels per

input? Assume blocking to be less than .002 and loading is .2 E per channel and determine the complexity of the switch. (7)

(c) Sketch an STS network to connect m incoming highways to m outgoing highways each carrying n PCM channels and having k time switch links. Explain how it works. (6)

(d) Explain necessity of combination switching. Compare the STS switch to TST switch. (6) (e) Write a short note on digital cross-connect system and its hierarchy. (6)(f) A TST network has 10 incoming highways and 10 outgoing highways, each carrying 32 channels. The

average occupancy of the incoming channel is 0.6 E. derive an equivalent space division network and estimate the blocking probability. (6)


(a) Compare call congestion and tine congestion in telephone network. During busy hours, 1400 calls were offered to a group

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