Displaying reports 54881-54900 of 84690.Go to page Start 2741 2742 2743 2744 2745 2746 2747 2748 2749 End
Reports until 22:38, Tuesday 18 October 2016
H1 ISC (DetChar, SUS, SYS)
jeffrey.kissel@LIGO.ORG - posted 22:38, Tuesday 18 October 2016 (30646)
Input Arm HXTS Highest Vertical (V3 / Bounce) Modes Characterized -- Not the Source of Mystery Peaks in LSC Aux Loops
J. Kissel

We're continuing to struggle to even get back to DRMI locking as of last night (LHO aLOG 30614). One suspicion is the sharp feature 27.0977 Hz (using a 0.005 Hz BW ASD) that has suddenly appeared, as shown in Jenne's attached ASD. 

Because we haven't yet measured them, and we're dead in the water until we figure out the problem, I've taken the time to excite and measure all of the HAM2 and HAM3 HSTS and HLTS's highest vertical mode frequencies, modeled to be at 27.3 Hz and 28.1 Hz, respectively. The results are as follows:

 Optic      Sus. Type     V3 Mode Freq (Hz)
  MC1         HSTS            27.387
  MC2         HSTS            27.742
  MC3         HSTS            27.426

  PRM         HSTS            27.594
  PR2         HSTS            27.414

  PR3         HLTS            28.211

None match up with the mystery line. The closest is MC1, at ~0.3 Hz away.

All values were measured with 5 averages at 0.005 Hz BW. I attach screenshots of the DTT and awggui templates for MC3 as an example. The DTT templates have been copied and committed into the Sus repository here:
/ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/PR3/Common/2016-10-18_H1SUSPR3_V3_Mode.xml
/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/MC1/Common/2016-10-18_H1SUSMC1_V3_Mode.xml
/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/MC2/Common/2016-10-18_H1SUSMC2_V3_Mode.xml
/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/MC3/Common/2016-10-18_H1SUSMC3_V3_Mode.xml
/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PR2/Common/2016-10-18_H1SUSPR2_V3_Mode.xml
/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PRM/Common/2016-10-18_H1SUSPRM_V3_Mode.xml
Images attached to this report
H1 TCS (TCS)
edmond.merilh@LIGO.ORG - posted 18:26, Tuesday 18 October 2016 (30644)
HWS camera work at EX

Some work was started on the HWS camera on ISCTEX today as per WP6253. It wasn't completed but brought to a point where it can be completed realtively easily at the next opportunity. It was returned to it's original configuration and confirmed to still be operational as it was before the work was started.

H1 CAL (CAL)
travis.sadecki@LIGO.ORG - posted 17:43, Tuesday 18 October 2016 - last comment - 12:58, Monday 24 October 2016(30642)
PCal X and Y OFS Optimization

Rick, Evan G., Travis

As part of the bi-annual PCal maintenance, today we optimized the drive range of the PCal OFS for both end stations.  The procedure for this was:

1) Turn off PCal lines and inject 10 Hz sine wave.

2) Break the OFS lock.

3) Note that the AOM drive is large (~1.5V) with loop open.

4) Adjust the offset in 1V steps to find the maximum OFS PD output.

5) Record max OFS PD output.

6) Close shutter and record minimum OFS PD output.

7) Set offset to half of 95% of max OFS PD output.

8) Find amplitude of injected sine wave that give us the maximum p-p OFS PD voltage.

9) Record magnitudes of carrier and sideband frequencies of the OFS and TX PDs.

Results:

PCal X:

Max OFS PD out = 10.5 V
95% of Max OFS PD out = 10 V p-p
OFS PD output with shutter closed = -0.01 V
Offset set to 5.00 V
64000 cts. peak is maximum - > ~10V p-p
 
Harmonics:
OFS PD
carrier 14 dB
1st SB -42.7 dB
2nd SB -43.5 dB
TX PD
carrier -234 dB
1st SB -294 dB
2nd SB -291.1 dB
 
Max modulation at 90% of this value - > 57,000 cts. PEAK (out of 64000 cts.)

 

PCal Y:

Max OFS PD out = 7.9 V
95% of Max OFS PD out -> 7.5 Vp-p
OFS PD output with shutter closed = -0.01
Offset set to 3.75 V
49000 its peak is maximum -> ~7.5V p-p
 
Harmonics:
OFS PD
carrier 11.75 dB
1st SB -67.4 dB
2nd SB -56 dB
TX PD
carrier -230.2 dB
1st SB -294.5 dB
2nd SB -295.1 dB
 
Max modulation at 90% of this value - > 44,000 cts. PEAK (out of 49000 cts.)
Comments related to this report
travis.sadecki@LIGO.ORG - 10:28, Wednesday 19 October 2016 (30655)

As the final part of the maintenance for PCal Y, we took a transfer function of the OFS.  See attached traces.

Images attached to this comment
evan.goetz@LIGO.ORG - 12:58, Monday 24 October 2016 (30802)CAL, INJ
The limit on the excitation amplitude is total number of counts that should be allowed to be sent to the Pcal. This is a frequency independent value. So for Pcal Y, the the maximum in H1:CAL-PCALY_EXE_SUM should be no larger than 44,000 counts. For Pcal X, the total of H1:CAL-PCALX_EXE_SUM and H1:CAL-PINJX_HARDWARE_OUT should be less than 57,000 counts.

Right now, Pcal Y has the following injections set:

Freq. (Hz)     Amp. (cts)
-------------------------
   7.9         20000.0
  36.7           750.0
 331.9          9000.0
1083.7         15000.0
-------------------------
Total = 44750.0

This is just above the threshold. It might be worth returning the 331.9 Hz line to O1 level (see LHO aLOG 30476 for the increased amplitude lines) since the detector noise in this region is recently improved.

Pcal X has the following injections set:

Freq. (Hz)     Amp. (cts)
-------------------------
1501.3         39322.0

And CW injections on the Pcal X are totaling ~1585 counts giving Total = 40907.

H1 ISC (ISC)
marc.pirello@LIGO.ORG - posted 16:41, Tuesday 18 October 2016 (30633)
RF Concentrator Readback Status

M. Pirello

Work Permit: #6246 & #6248

Prior to working on this we determined that the analog voltages on the channels in questions are outputting anticipated values.  The immediate problem is with the PowerOK bit for each of these signals.

Investigation into these chassis yeilded the following:

1.  Upon rebooting RF Amp Concentrator #1 on ISC_C3 in the CER (S1103450) the stuck bits on that chassis AMP18M and AMP24M1 were reset.  We are 2/3 of the way done with this task, piece of cake!

2.  Upon rebooting RF Amp Concentrator #2 on ISC_C3 in the CER (S1103451) 3 new bits were stuck for a total of 4 bits,  including the original DIV40M, drat!

3. I tried disconnecting, measuring, and reconnecting each of the 4 stuck signals on the DB25's on the back of the unit.  These voltages look good, no luck resetting the latched bits here.

     a.  DB25#1 = DIV40M = 3.64V 

     b.  DB25#2 = AMP40M = 3.75V

     c.  DB25#3 = DIV10M = 3.61V

     d.  DB25#4 = AMP10M = 3.67V

4.  I then disconnected the DB37 on RF Amp Concentrator #2 (S1103451) and checked each signal coming out of the RF Amp Concentrator.  This output is confusing.  The I couplers inside are referenced to 5V.  An on state should be 5V, off state should be 0V.  All of the PO signals should be either 5V or 0V.  PO11 is 2.5V, PO7 is 2.5V, PO2 is 2.5V.

PIn 1 (M1P12) 0V Pin 11 (M1P2) 0V Pin 21 (M1N11) 0.033V Pin 31 (M1N1) 0.004V
Pin 2 (M1P11) 0V Pin 12 (M1P1) 0V Pin 22 (M1N10) 0.029V Pin 32 (PO8) 0.009V
Pin 3 (M1P10) 3.4V Pin 13 (PO12) 0.008V Pin 23 (M1N9) 0.029V Pin 33 (PO11) 2.509V
Pin 4 (M1P9) 2.598V Pin 14 (PO4) 0.008V Pin 24 (M1N8) 0.0228V Pin 34 (PO3) 0.005V
Pin 5 (M1P8) 0V Pin 15 (PO7) 2.510V Pin 25 (M1N7) 0.002V Pin 35 (PO6) 0.006V
Pin 6 (M1P7) 2.951V Pin 16 (PO10) 0.007 Pin 26 (M1N6) 0.033V Pin 36 (PO9) 0.004V
Pin 7 (M1P6) 3.073V Pin 17 (PO2) 2.515V Pin 27 (M1N5) 0.033V  Pin 37 (PO1) 0.003V
Pin 8 (M1P5) 3.027V Pin 18 (PO5) 0.004V Pin 28 (M1N4) 0.005V    
Pin 9 (M1P4) 3.051V Pin 19 (GND) GND Pin 29 (M1N3) 0.004V    
Pin 10 (M1P3) 0V Pin 20 (M1N12) 0.029V Pin 30 (M1N2) 0.004V    

5.  I then reconnected the DB37 to H1_EtherCAT_Corner_3.  Ten out of twelve of the OK bits remained red.  I recycled power on the RF Amp Concentrator #2 (S1103451) on ISC_3 and again all but 4 of the OK bits were green like before.

6.  I put everything back together, removed the breakout boards, etc.  When I left the CER, the 4 bits were latched, DIV40M, AMP40M, DIV10M, AMP10M.  After noon I checked the OK bits and 10 out of 12 OK bits are red including the original four.  I am relatively sure that the issue is with the RF Amp Concentrator. The power OK signals going into this chassis are good, the power OK signals coming out of it seem to latch up spontaneously and output bad voltages.  Perhaps the 5V regulator is outputting 2.5V?

Recommendation:

Strike DIV40M from WP6248 and close out WP6248 and FRS 6391 because DIV40M is connected to a different chassis. Expand FRS 6059 to encompass RF Amp Concentrator #2 (S1103451) and work to debug the source of the spontaneous latchup/latchdown and bad voltages (including DIV40M).

Images attached to this report
H1 DAQ
david.barker@LIGO.ORG - posted 16:36, Tuesday 18 October 2016 (30641)
new DAQ overview, shows retransmisison stats and removed science frame reporting

note that fw2 and tw1 have issued retransmission requests since the last daq restart

Images attached to this report
H1 DAQ
david.barker@LIGO.ORG - posted 16:26, Tuesday 18 October 2016 (30639)
DAQ daqd and OS summary

Here are the current versions of daqd and nds Jonathan built and installed today:

daqd-process-catagory operating system(s) machines
data concentrator gentoo h1dc0
frame writer ubuntu12, gentoo* h1fw0, h1fw1, h1fw2, h1tw0, h1tw1*
nds-1 server gentoo h1nds0, h1nds1
frame broadcaster (dmt) gentoo h1broadcaster0

Note that h1tw0 was upgraded to U12 because it was showing RAID errors, h1tw1 has been kept back with it original Gentoo OS (these machines were the original frame writers)

here is the nds process table (NDS-1 servers run two processes; daqd and nds)

nds-process-catagory operating system machines
nds-1 server gentoo h1nds0, h1nds1
H1 TCS
betsy.weaver@LIGO.ORG - posted 16:16, Tuesday 18 October 2016 - last comment - 16:33, Tuesday 18 October 2016(30638)
TCSY CHiller... on going

Today, I calculated the volume of piping that feeds the circulation loop for the TCSY laser.  The total volume of water in the piping alone (to and from the laser to the chiller on the mech room mezzanine) to be 36 liters.  Wow, much more than I had assumed!  The chiller reservoir holds 7 liters, for a total of 43L in the system at any given "full" time.

Recall that the system popped a mesh filter and ran the reservoir dry on Sept 28th alog 30041 - at which time only 6L was added to ~fill the reservoir.  At the time, they also noticed that there was air in noisy lines down at the table so there was air pushed through some or all of the piping volume (at least the chiller->laser piping was full of air as they mentioned, so half of the 36L piping would have needed to be refilled).

I've added up the small-ish amounts of water we have been adding daily to keep the chiller reservoir topped off - we have added 10.5L over the last 3 weeks.  With the 6L added Sept 28th, we've added 16.5L to a 43L system so far.  Even assuming there was some water still in the pipes during the Sept 28th "leak", we likley still have a ways to go before we have the system full.

Keep on filling...

 

(From VE drawings, I estimated ~2880" of piping length round trip chiller-laser-chiller.  The piping ID looks to be 1".)

Comments related to this report
alastair.heptonstall@LIGO.ORG - 16:33, Tuesday 18 October 2016 (30640)

That's around the same volume I had calculated for flushing the chillers (I think I had ~10 gallons).  So we're getting the same number there.

H1 CDS (DAQ)
david.barker@LIGO.ORG - posted 16:14, Tuesday 18 October 2016 - last comment - 08:20, Wednesday 19 October 2016(30637)
CDS maintenance summary, Tuesday 18th October 2016

WP6251 RCG3.2 upgrade

Jonathan, Jim, Dave:

The main work today was in upgrading the front end models and the DAQ systems to RCG3.2. All models were recompiled yesterday evening (see alog 30609). This morning we installed this new code (took 1hr 27mins). New mx code was compiled, new daqd binaries were created for all DAQ systems. The install sequence was:

WP6258 DAQ removal of science frame

Jonathan, Greg, Jim, Dave:

All frame writers were configured to no longer write science frames, and rename the old commissioning frames as the new raw frame.

Detailed procedure given in wiki page https://lhocds.ligo-wa.caltech.edu/wiki/MakingTheCommissioningFrameTheNewFullFrame

After this change, there are no C-named frames, only R-named frames. Archived C-Frames are now R-Frames, new frames are what were previously called commissioning frames with R-names in the frames/full directories. What were called science frames are not written, no new frames in frames/science directories.

h1nds0 and h1nds1 were reconfigured to the new R-names and restarted

the wiper scripts on h1ldasgw0 and h1ldasgw1 were changed to not use science frames, and to give the disk these frames used to the full frames instead

WP6237 Remove h1ldasgw2

Jim, Dave

a third QFS/NFS server was install in the MSR during the summer as part of the attempt to fix h1fw0/h1fw1 instability. It offloaded the exporting of the frame directories (in read-only mode) to the NDS servers. It later proved to be a liability when corrupted frame files were served by h1ldasgw2 to both NDS servers.

Today we decommissioned h1ldasgw2 and reconfigured h1ldasgw0, h1ldasgw1 to serve their respective file systems as a read-only export to the NDS machines. h1nds0 and h1nds1 were configured to no longer use h1ldasgw2.

Comments related to this report
james.batch@LIGO.ORG - 08:20, Wednesday 19 October 2016 (30653)
A new version of dataviewer was also installed for Ubuntu12 and Ubuntu14 control room workstations.  This version, 3.2, will handle the leap second to be applied Dec. 31, 2016.  Dataviewer is part of the advLigoRTS source code.
H1 General
jim.warner@LIGO.ORG - posted 16:09, Tuesday 18 October 2016 (30636)
Day Shift Summary

TITLE: 10/17 Eve Shift: 15:00-23:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Lock Aquisition

SHIFT SUMMARY: We restarted the world, now initial alignment, fss, iss and pmc are being fun.

15:15 Christina to LVEA
15:30 JoeD to LVEA
15:45 Marc to CER, Alfredo to LVEA
15:45 Fil ed to EY to look at HWS cabling
16:00 Jason to PSL
16:15 Ed to EX  to work on HWS
16:15 Fil to LVEA for RGA
16:30 Gerardo to EY
17:30 Alfredo to EY
18:45 Kyle to LVEA
19:00 Marc to EX/EY
20:15 Kyle to EX
20:30 Fil to EY
20:30 Chandra to MY

 

 
15:15 Christina to LVEA
15:30 JoeD to LVEA
15:45 Marc to CER, Alfredo to LVEA
15:45 Fil ed to EY to look at HWS cabling
16:00 Jason to PSL
16:15 Ed to EX  to work on HWS
16:15 Fil to LVEA for RGA
16:30 Gerardo to EY
17:30 Alfredo to EY
18:45 Kyle to LVEA
19:00 Marc to EX/EY
20:15 Kyle to EX
20:30 Fil to EY

 

20:30 Chandra to MY
LHO VE (CDS)
filiberto.clara@LIGO.ORG - posted 15:53, Tuesday 18 October 2016 (30635)
RGA Cabling update

WP 6176
WP 6247

Pulled in new power and network cables for the RGA (next to HAM4). Cables need to be terminated.
Cables at EY were terminated.

LHO VE
kyle.ryan@LIGO.ORG - posted 15:23, Tuesday 18 October 2016 (30634)
Moved battery packs from outbuilding main turbo pumps to corner station for long-term storage/charging
Each main turbo pump (MTP) has an adjoining box containing (4) ea. 12v 18Ah sealed lead acid (SLA) batteries connected in series that provide 48VDC for pump rotor levitation during loss of AC power.  These only get charged when the turbo controllers are energized.  As preventative maintenance during the prolonged periods of pump inactivity, we would energize the controllers for a few hours during Tuesday's maintenance period.  We now will keep these battery packs centrally located (hallway between AHU1 and AHU2 in the Corner Station Fan room) and on a battery tender.  The trade off is that we now will need to remember to take a battery pack with us when activating an MTP at an outbuilding.  

LHO General
bubba.gateley@LIGO.ORG - posted 15:19, Tuesday 18 October 2016 (30632)
Empty BSC LTS storage container weight and Partial Weight of Loaded BSC LTS storage container
This morning, Chandra and I weighed an empty BSC LTS container. After weighing that container, we decided to check the weight on a loaded BSC LTS container. The loaded container never lifted off the floor. The crane capacity is only 10,000 lbs. and another 380 lbs. would not have lifted the container.   The results are in the photos here. 
Images attached to this report
LHO VE (VE)
gerardo.moreno@LIGO.ORG - posted 15:10, Tuesday 18 October 2016 (30631)
Serviced Compressors #3, #4, and #5 at Y-End Vent/Purge-Air Skid

(Kyle, Gerardo)

Today compressors #3, #4, and #5 were all greased and pressure tested.

All compressors passed their compression test, #3 at 120 psi, #4 at 120 psi, and #5 at 130 psi.
Then all compressors and electrical motors were greased.

All compressor assemblies were run tested after service was performed.

Work performed under WP#6257.

LHO VE
kyle.ryan@LIGO.ORG - posted 15:05, Tuesday 18 October 2016 (30630)
Running rotating-shaft pumps in VEA while baking RGA @ X-end
(See WPs #6221 and #6255)

Will need to make daily check each morning.  Plan to run through 10/23 inclusive unless too egregious for commissioners
H1 ISC (ISC)
marc.pirello@LIGO.ORG - posted 13:51, Tuesday 18 October 2016 - last comment - 14:04, Tuesday 18 October 2016(30625)
Timing Comparator Code Update (v5)

M. Pirello

This FPGA code ( E1200034 ) disconnects the 1pps signal from the 4 internal LED's and grounds them.  All four timing comparators at LHO were updated to v5.

S1107952 in the CER

S1201224 in the MSR

S1201886 at X end

S1201222 at Y end

Work Permit 6256

Comments related to this report
daniel.sigg@LIGO.ORG - 14:04, Tuesday 18 October 2016 (30628)

TwinCAT code has been updated to recognize the new SVN number.

H1 ISC (OpsInfo)
cheryl.vorvick@LIGO.ORG - posted 13:07, Tuesday 18 October 2016 - last comment - 14:04, Tuesday 18 October 2016(30624)
ALS Shutter Control Map

The medm SYS_CUST_SHUTTER_SUMMARY.adl shows the ALS shutters, but the names are wrong.  Attached is a map of what each shutter did today.

Images attached to this report
Comments related to this report
daniel.sigg@LIGO.ORG - 14:04, Tuesday 18 October 2016 (30627)

I guess we should file a FRS for EY. Controller channel 1 is unworkable for a while.

H1 ISC
daniel.sigg@LIGO.ORG - posted 08:27, Monday 17 October 2016 - last comment - 15:00, Tuesday 18 October 2016(30585)
Direct jitter coupling into REFL

Looking at the coupling of carrier jitter with misaligned RF sidebands in REFL:

Jitter (alog 30237): 10-6/√Hz (level) to n x 10-4/√Hz (peaks)
IMC suppression (alog 30124): ~1⁄200
⇒ at IFO: 5 x 10-9/√Hz to n⁄2 x 10-6/√Hz

Fixed misalignment of RF sidebands: Δα < 0.3
DC power in reflection with unlocked ifo at 50W: REFLDCunlocked ~ 300 mW
Error offset in REFL = jitter * REFLDCunlocked * Δα
⇒ 5 x 10-9/√Hz  * 0.3 W * 0.1 ~ 1.5 x 10-10 W/√Hz (low)
n⁄2 x 10-6/√Hz * 0.3 W * 0.3 ~ n⁄2 x 10-7/√Hz (high)

Frequency noise coupling into DARM (alog 29893):
⇒10-10 m/W at 1kHz (approx. f-slope)

at 1kHz: 10-20 m to 10-17 m
at 300 Hz: n x 10-18 m (high) with periscope peak n ~ 4.

This seems at least a plausible coupling mechanism to explain our excess jitter noise.

Comments related to this report
daniel.sigg@LIGO.ORG - 15:00, Tuesday 18 October 2016 (30629)

Some additional comments:

This calculation estimates the jitter noise at the input to the ifo by forward propagating the measured jitter into the IMC. It then assumes a jitter coupling in reflection that mixes the carrier jitter with a RF sideband TEM10 mode due to misalignment. The corresponding RF signal would be an error point offset in the frequency suppression servo, so it would be added to the frequency noise. Finally, we are using the frequency noise to OMC DCPD coupling function to estimate how much would show up in DARM.

If this is the main jitter coupling path, it will show up in POP9I as long as it is above the shot noise. Indeed, alog 30610 shows the POP9I inferred frequency noise (out-of-loop) more than an order of magnitude above the one inferred from REFL9I (in-loop) at 100Hz. It isn't large enough to explain the noise visible in DARM. However, it is not far below the expected level for 50W shot noise.

H1 CDS (Lockloss)
sheila.dwyer@LIGO.ORG - posted 01:04, Wednesday 12 October 2016 - last comment - 17:11, Tuesday 18 October 2016(30439)
lockloss tool not working

 Possibly after some changes made durring maintence, the lockloss tool stopped working. I can use lockloss plot, but not select. 

sheila.dwyer@opsws4:~/Desktop/Locklosses$ lockloss -c channels_to_look_at_TR_CARM.txt select

Traceback (most recent call last):
  File "/ligo/cds/userscripts/lockloss", line 403, in <module>
    args.func(args)
  File "/ligo/cds/userscripts/lockloss", line 254, in cmd_select
    selected = select_lockloss_time(index=args.index, tz=args.tz)
  File "/ligo/cds/userscripts/lockloss", line 137, in select_lockloss_time
    times = list(get_guard_lockloss_events())[::-1]
  File "/ligo/cds/userscripts/lockloss", line 112, in get_guard_lockloss_events
    for t in guardutil.nds.find_transitions(GRD_LOCKING_NODE, t0, t1):
  File "/ligo/apps/linux-x86_64/guardian-1.0.3/lib/python2.7/site-packages/guardutil/nds.py", line 32, in find_transitions
    for buf in conn.iterate(t0, t1, [channel]):
RuntimeError: Requested data were not found.
Comments related to this report
sheila.dwyer@LIGO.ORG - 02:19, Tuesday 18 October 2016 (30615)

After noticing LLO alog 28710 I tried to svn up the lockloss script (we're at rev 14462 now), but I still get the same error when I try to use select

jameson.rollins@LIGO.ORG - 17:11, Tuesday 18 October 2016 (30643)

The problem at LLO is totally different and unrelated.

The exception you're seeing is from an NDS access failure.  The daq NDS1 server is saying that it can't find the data that is being requested.  This can happen if you request data too recent in the past.  It also used to happen because of gaps in the NDS1 lookback buffer, but those should have been mostly fixed.

Right now the lockloss tool is looking for all lock loss events from 36 hours ago to 1 second ago.  The 1 second ago part could be the problem, if that's too soon for the NDS1 server to handle.  But my testing has indicated that 1 second in the past should be sufficient for the data to be available.  In other words I've not been able to recreate the problem.

In any event, I changed the look-back to go up to only two seconds in the past.  Hopefully that fixes the issue.

Displaying reports 54881-54900 of 84690.Go to page Start 2741 2742 2743 2744 2745 2746 2747 2748 2749 End