Uninterruptible power supplies

Before we learn about UPS system first let we check out what is full form of UPS. There are several applications of UPS where even a temporary power failure can cause a great deal of public inconvenience leading to large economic losses. UPS can be used in electrical equipment where unexpected power disruption could cause injuries, serious business, or data losses, and also some many more advantages of the UPS system. Earlier UPS systems were based on an arrangement shown in the figure. 

 Working of rotating type UPS system :
  • This scheme is usually called rotating types UPS. This arrangement consists of DC motor driven alternator, the shaft of which is also coupled to a diesel engine. 
  • The UPS system needed is taken from the alternator output terminals. When the main supply fails, the diesel engine is run to take over the load. 
  • The battery bank is able to maintain the alternator speed through the dc motor and the flywheel, thus giving a no break supply to the critical load.
  • Static UPS system is two types, short break UPS and no break UPS. 
Short  break UPS :
  • In a situation where short interruption in supply can be tolerated, the short break UPS showed in the figure. In this system, the main ac supply is rectified to dc.
  • This dc output from the rectifier charges the batteries and is also converted to ac by an inverter. After passing through the filter, AC can be delivered to load in case normally off contacts are closed.
 No break UPS  :
  • When no break UPS supply is required, the static UPS system shown in the figure. In this supply is rectified and the delivered power to maintain the required charge on the batteries. 
When users no break UPS system has the following advantages :
  • The inverter can be used to condition the supply delivered to load
  • Load gets protected from transients in the main ac supply
  • The inverter output frequency can be maintained at the desired value In case of inverter failure is detected, the load is switched on the main ac supply directly by turning on the normally off static switch and opening the normally on a static switch.
The standby batteries in the UPS system are either nickel-cadmium or lead-acid types. NC battery has the following advantages :
  • Their electrolyte is non-corrosive. 
  • Their electrolyte does not emit an explosive gas when charging
  • NC batteries cannot be damaged by overcharging or discharging, these have therefore longer life
  • Cost of  NC  batteries is like, however, two or three times that of lead acid batteries.

Full form related to microprocessor X86 programming

Full form related to microprocessor X86 programming

DOS - Disk operating system
CPU - Central processing unit
HLL  - High level language
SSU - Secondary storage unit
IU - Input unit
OU - Output unit
FLOPS - Floating point operation per second
MIPS - Million instruction per second
CU - Control unit
ALU - Arithmetic logic unit
ROM - Read only memory 
RAM - Random access memory
BIU - Bus interface unit
IQ - Instruction queue
CSR - Code segment register 
DSR - Data segment register
ESR - Extra segment register
EU - Execution unit
CF - Carry flag
PF - Parity flag
IF - Interrupt flag
OF - Overflow flag
SF - Sign flag
ZF - Zero flag
TF - Trap flag
DF - Direction flag
U - Undefined 
IP - Instruction Pointer
LIFO - Last in first out
ENDP - End of procedure
EPDM - End of macro
EXTRN - External
PTR - Pointer
LEA - Load effective address
LDS - Load register and DS register
LES - Load register and ES register
LAHF - Load AH with flags
SAHF - Store AH in flag register
SHL - Shift logical left
SAR - Shift arithmetic right
SAL - Shift arithmetic left
POPF - Pop flag register
POPA - Pop all registers
POP - Pop register
PUSHA - Push all register\
ROL  - Rotate left
ROR - Rotate right
RCL - Rotate through carry left
RCR - Rotate through carry right
ADD - Addition
ADC - Addition with carry
INC  - Increment
SUB - Subtraction
SBB - Subtract with borrow
AAA - ASCII adjust for addition
AAS - ASCII adjust for subtraction
AAM - ASCII adjust for multiplication
AAD - ASCII adjust for division
DAA - Decimal adjust for addition
DAS - Decimal adjust for subtraction
MUL  - Multiplication
IMUL - Integer multiply
DIV - Division
IDIV - Integer division
CBW - Convert byte to word
CWD - Convert word to double word
TEST - Test and set flags
XOR - Logical exclusive OR
JMP - Jump
NOT - Logically not
JAE - Jump on above or equal 
JNB - Jump or not below
JNC- Jump on not carry
JNBE - Jump on not below or equal 
JB - Jump on below
JNAE - Jump or not above or equal
JC - Jump on carry
JE - Jump on equal
JZ - Jump on zero
JG - Jump on greater than
JNLE - Jump on not less or equal
JGE - Jump on grater or equal
JNL - Jump on not less
JL - Jump on less than
JNGE - Jump on not greater than or equal
JLE - Jump or less than or equal
JNG - Jump or not greater
JNE - Jump on not equal
JNZ - Jump or not zero
JNO - Jump on not overflow
JNP - Jump on not parity
JPO - Jump on parity odd
JNS - Jump on not sign
JO - Jump on overflow
JP - Jump on parity even
JPE - Jump on parity equal
JS - Jump on sign
IRET - Interrupt return
INTO - Interrupt on overflow
CLC - Clear carry
CMC - Complement carry
STC - set carry
CLD - Clear direction flag
STD - Set direction flag
CLL - Clear interrupt flag
STI - Set interrupt flag
HLT - Halt
NOP - No operation
WAIT/FWAIT - Wait or Floating wait
LOCK - Lock shared resources
CLD - Clear direction flag
STD - Set direction flag
MOVS - Moves string
MOVSB - Moves string string byte
MOVSW - Moves string word
LODS - Load string
LODSB - Load string byte
LODSW - Load string word
CMPS - Compare string
CMPSB - Compare string byte
CMPSW - Compare string word
STOS - Store string
STOSB - Store string byte
STOSW - Store string word

Advantages and disadvantages of frequency hopping spread spectrum

There are some of the advantages of frequency hopping spread spectrum (FH-SS) given below :
  • It has less distance effect.
  • Provide the greatest amount of spreading.
  • The bandwidth of these systems is large.
  • It has a short acquisition time.
  • Best discrimination against multi-path.
  • Very large bandwidth.
  • The synchronization is not greatly dependent on distance.
  • This system can be programmed to avoid some part of the spectrum.
  • It needs complex and costly digital frequency synthesizers are required to be used.
  • It needs error detection.
  • The processing gain is higher than that of a direct sequence spread spectrum.
  • This system is not useful for the range and range rate measurement.
  • The modulation scheme has become obsolete.
Some more advantages of FH/SS compared to DS/SS is given below :
  • FS/SS is less susceptible to be near-far problems than DS/SS.
  • The processing gain is higher than that of system DS/SS.
  • FH/SS can produce signals of wider bandwidth than DS/SS.
  • In FS/SS the problem of a relative power level of co-channel signals is not critical as than DS/SS.
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Advantages and disadvantages of GSM

GSM is a cellular technology used for transmitting mobile voice and data services developed by European Telecommunications standards Institutes to describe the protocols for second generation digital cellular networks. 

 GSM provides standard features like cell phone encryption, data networking, caller ID, call forwarding, call waiting, SMS and conferencing and it can be used in an application like home automation, mobile technology, toll collection, energy conversion etc. GSM has both advantages and disadvantages of which consumers should be aware of. 

Advantages of GSM :
  • More suitable network with robust features.
  • No roaming charges on International calls. 
  • Worldwide connectivity and extensive coverage. 
  • SAIC and DAIC techniques used in GSM provide very high transmission quality. 
  • The phone works based on the SIM card so that it is easy to change the different varieties of phones by users. 
  • GSM signals don't have any deterioration. 
  • Easy to integrate GSM with other wireless technology such as CDMA and LTE.
  • It has the ability to use repeaters. 
  • Because of the pulse nature of transmission talk time is generally high.
Disadvantages of GSM :
  • Bandwidth lag because of multiple users shares the same bandwidth so the transmission can encounter interface. 
  • It can interfere with certain electronics, such as hearing aids that are due to pulse transmission technology. As a result, many locations, such as hospitals, airports and petrol pumps require cell phones to be turned off. 
  • To increase coverage repeaters are required to be installed. 
  • It provided limited data rate capability so for high data rate advanced version of GSM devices are used. 
  • Many of GSM technology is patented by Qualcomm thus license needs to be obtained from them. 
  • Manufacturers are not releasing IS-95 devices due to the lack of a big market so IS-95 is normally installed in the small tower. 
  • GSM has fixed maximum call sites range up to 35 km that is very limited. 
  • There is no end-to-end encryption of user data. 
  • Several incompatibilities within the GSM standards. 
  • Electromagnetic radiation is more with the use of GSM.
  • Macrocells affected by the multipath signal loss.

Static switch definition

A switch having no moving part called as a static switch. Power semiconductor devices which can be turned on and off within a few microseconds can be used as fast acting static switches.

Static switches can be also used for latching, current and voltage detection, a time delay circuit, transducers etc.

A static switch is two types :
  1. AC switches
  2. DC switches 
If we are using input is ac then ac SS are used while we are using input is DC, DC SS are used. Switching speed for AC switches is governed by the supply frequency and turn off time of thyristor (SCR). 

For DC static switches, the switches speed depends on the commutation circuitry and turn off time of fast thyristor. AC switches may be single phase or three phases. 

 Static switches do not change or control the power delivered to load as it is done in a single phase voltage controller In a static switch, the semiconductor switches are turned on at zero crossing of the load current, whereas it is not so single-phase voltage controller.

 Static switches are now replacing mechanical and electromechanical switches because of several advantages listed below.
  • A static switch has no moving parts, It maintenance is therefore very low
  • A static switch has a long operational life
  • A static switch has no bouncing at the time of turning on
  • On time of a static switch is of the order of 3 microseconds, it has therefore very high switching speed
  • Inbuilt AC overvoltage protection
  • High-performance AC line quality monitoring

Advantages of static switches

Static switches are now replacing mechanical and electromechanical switches  both because of several advantages are listed below :
  • A static switch has no moving parts, therefore, maintenance cost  is very low
  • A static switch has a long operational life
  • A static switch has no bouncing at the time of when is turning on
  • On time of a static switch is of the order microseconds, it has therefore very high switching speed
  • Inbuilt AC overvoltage protection
  • High-performance AC line quality monitoring

What is frequency hopping spread spectrum

Frequency hopping spread spectrum is a method of transmitting radio signals by rapidly switching a carrier.  

 In FHSS among many frequency channels using pseudorandom sequence known to both transmitter and receiver. 

 Overview :

 In FHSS the data bits that are transmitted in the different frequency slots are changed by the PN sequence.

 FHSS is often used as a method to allow multiple transmitter and receiver pairs, it can operate in the same space on he same broad channel at the same time.

 In FHSS the data sequence is spread over small frequency slots of the spread spectrum signal.

FHSS is a wireless technology that spreads its signal over rapidly changing frequencies. 

 Advantages and disadvantages :

 The advantages of Frequency hopping spread spectrum given below :
  • It has less distance effect.
  • Provide greatest amount of spreading.
  • The bandwidth of these system is large.
  • It has a short acquisition time.
  • Best discrimination against multi-path.
  • Very large bandwidth.
  • The synchronization is not greatly dependent on distance.
  • It can be programmed to avoid some part of the spectrum.
Disadvantages of Frequency hopping spread spectrum given below :
  • It needs complex and costly digital frequency synthesizers are required to be used.
  • It need error detection.
  • The processing gain is higher than that of direct sequence spread spectrum.
  • It is not useful for range and range rate measurement.
Application :
  • Wireless local area network standard for Wi-Fi.
  • Military communication equipment.
  • Wireless personal area network standard for bluetooth.

Difference between DSSS and FHSS

DSSS and FHSS both are spread spectrum techniques. There is some difference between spreading the data into the wider bandwidth. FHSS using frequency hopping while DSSS using pseudo noise to modify the phase of the signal. So in this article, you can check some difference between these two spread spectrum. 


Difference :
  • Over the complete bandwidth of the spread spectrum signal, the data sequence is spread in DSSS but in FHSS the data sequence is spread over small frequency slots of the spread spectrum signal.
  • Cost is more in DSSS compare to FHSS.
  • DSSS is relative distance and the system, FHSS is less affected by distance change.
  • DSSS used the BPSK method and FHSS used many FSK methods.
  • The acquisition time of  DSSS is long while in short in case of FHSS.
  • Dwell time is 400 ms in FHSS but in DSSS has no dwell time. 
  • Used density is less in DSSS but in more in FHSS.
  • Chip rate Rc = 1 /  Tc in DSSS and Chip rate for FHSS is Rc = max (Rh,Rs).
  • Interoperability is high in DSSS while low in FHSS. 
  • DSSS changes the phase wheres FHSS changes the frequency being used. 
  • FHSS is easier to synchronize than DSSS.
  • DSSS used in positioning systems while FHSS is not.
  • DSSS delivers capacity up to 11 Mbps but in FHSS supports up to 3 Mbps.
  • DSSS is a very sensitive technology while FHSS is a robust one. 
  • DSSS ideal for point to point applications while in FHSS can be used in point to multi-point deployment with better performance. 
  • DSSS systems use a carrier that remains fixed to a specific frequency band while FHSS systems use a radio carrier that 'hops' from frequency to frequency in a pattern known as transmitter and receiver. 
  • Frequencies are randomized in case of FHSS but in constant in case of DSSS. 
  • Data is constant is the case of FHSS while randomize in case of DSSS.
  • FHSS spreads the signal by hopping with a bandwidth of 83 MHz while in using DSSS spreads the signal by adding redundant with a bandwidth of 22 MHz.
  • DSSS prone to errors but at a low level as compared to FHSS system. FHSS produces strong bursty errors. 
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Application of direct spread spectrum sequence

  • Cordless phones operating in the 900 MHz, 2.4 GHz and 5.8 GHz bands. 
  • United status GPS technology, European Galileo and Russian GLONASS satellite navigation systems used DS/SS system with a single PN code in conjunction with FDMA and later it is used to achieve CDMA with multiple PN code.  
  • Used in the low probability of intercept signal.
  • It obtain message privacy.
  • Used military and many commercial application.
  • The unique spreading codes support code division multiple access.
  • Support various decision making level.
  • To reject unintentional  interference.
  • To minimize self interference due to the multi-path propagation.
  • It is used in automatic meter reading. 
  • Used in IEEE 802 11b and Zigbee network. 
  • Radio controlled model automotive vehicles. 

Advantages and disadvantages of direct sequence spread spectrum

Advantages of DS/SS :
  • It has best noise and anti-jam performance.
  • Simple hard ware implementation.
  • It support high coverage range due to low SNR requirement at receiver.
  • Do no require high speed fast setting frequency synthesizer.
  • It has best discrimination against multi-path signals.
  • The unidentified receivers find it difficult to detect the direct sequence signals.
  • It can be employed in point to point application at the rate of 11 Mbps.
  • Determination of relative timing between transmitter and receiver. 
Disadvantages of DS/SS :
  • DS/SS has a longer acquisition time.
  • It require wideband channel with small phase distortion.
  • The pseudo noise generator must generate sequence at high rates.
  • Near-far problem.
  • Fast code generator needed.
  • The system is prone to error at lower than frequency hoping spread spectrum.
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What is direct sequence spread spectrum

Direct sequence spread spectrum (DSSS) is spread spectrum modulation technique used in telecommunication to reduce overall signal interface. 

 Direct sequence spread spectrum (DSSS) is one type of channel access method is better known as direct sequence CDMA. This is mainly used in IEEE 802.11b and also used  Zigbee technology. 

 Overview : 
  • The term DS/SS stands for direct sequence spread spectrum
  • In this method, the pseudo-random code is used when the signal can be detected at the receiver end. If avoid unauthorized signal access.
  • The DS/SS is affected by the near-far problem. This problem occurs because of the unequal power that is received by the user.
  • It is a very sensitive technology.
  • Many users can be used in the same band with a better signal to noise ratio. 
  • DS/SS is used point to point scenario.
  • The DS/SS signal spectrum is spread over a wide band while the PSD is small, Hence, it is simple to hide the signal within the noise floor.
  • DS/SS delivers capacity of about 11 Mbps.
Advantages of  DS/SS :
  • It has the best noise and antijam performance.
  • Simple hardware implementation.
  • It supports high coverage range due to low SNR requirement at receiver.
  • Do not require high-speed fast setting frequency synthesizer.
  • It has the best discrimination against multi-path signals.
  • The unidentified receivers find it difficult to detect the direct sequence type of signals.
  • It can be employed in point to point the application at the rate of 11 Mbps.
Disadvantages of DS/SS :
  • DS/SS has a longer acquisition time.
  • It requires a wideband channel with small phase distortion.
  • The pseudo noise generator must generate a sequence at high rates.
  • Near-far problem.
  • Fast code generator needed.
  • The system is prone to error at lower compared to FH/SS.
Application of DSSS :

 The application of direct spread spectrum analysis is listed below.
  • DSSS is used in the low probability of intercept signal.
  • It obtains message privacy.
  • It is used military and much commercial application.
  • It can support the unique spreading codes support code division multiple access.
  • Support various decision-making level.
  • To reject unintentional interference.
  • To minimize self-interference due to the multi-path propagation.
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CDMA 2000 reverse channel

The reverse link for CDMA 2000 has properties similar to the forward link of a signal. 
And also have CDMA 2000 user is assigned a forward channel that consists of the following combination :

  1. Forward fundamental channel  (F-FCH)
  2. 0-7: Forward supplemental code channel (F-SCHs) for both RC1 and RC2
  3. 0-2: Forward supplemental code channel (F-SCHs) for both RC3 and RC
The minimum configuration consists of a reverse pilot channel to enable the base station (BS) to perform synchronous detection and reverse fundamental channel for voice.
The different reverse channel is:
  1. Reverse supplemental channel (R-SCH)
  2. Reverse pilot channel (R-PICH)
  3. The reverse dedicated control channel (R-DCCH)
  4. Reverse enhanced access channel (R-EACH)
  5. The reverse common control channel (R-CCCH)
  6. Reverse fundamental channel (R-FCH)
  7. Reverse supplemental code channel (R-SCCH)
1. Reverse supplemental channel (R-SCH)
When the data rate is greater than 9.6 kbps, an R-SCH is needed. R-SCH channel is assigned for power control. A total of one or two R-SCH can be assigned per mobile unit.

2. Reverse pilot channel (R-PICH)
It provides pilot and power control information. It enables the mobile unit to transmit a lower power level and allow to inform the base station of the forward power levels being received, enabling the base station to reduce power.

3. Reverse enhanced access channel (R-EACH)
R-EACH is used to initiate communication with the base station. It is used by a mobile station, This channel also reduces the access channel power.

4. The reverse common control channel (R-CCCH)
This channel is used by the mobile unit to send their data information after they have granted access.

5. The reverse dedicated control channel (R-DCCH)
This channel replaces the dim and burst and the blank and burst. It is used for messaging and control for data calls.

6. Reverse fundamental channel (R-FCH)
This channel is used for voice and data payload. R-FCH is allowed shorter frame, this shorter frame can be used lower latency.

7. Reverse supplemental code channel (R-SCCH)
This channel is the same as F-SCCH and same it can be used with radio configuration. 

Application of CDMA 2000

  • Wireless internet
  • Location-based services
  • Wireless email 
  • Steaming video games
  • Telemetry
  • Wireless telecommunication
  • Longer standby battery life
  • Enterprise solutions
  • Wireless commerce
  • Web browsing
  • Multimedia services
  • Future demand for data service

Advantages of CDMA 2000

CDMA 2000 has unique features, benefits, and performance so it provides better advantages like high-voice capacity and high-speed packet data. Now we can check some more advantages one by one below.
  • Industry-leading performance.
  • Device selection.
  • Flexible migration path.
  • Flexible network architecture.
  • New common channel structure and operation.
  • Ubiquitous idle time operation.
  • Global roaming and multi-mode, multiband devices.
  • Flexible spectral allocation and efficient use of spectrum.
  • New MAC states for efficient.
  • Support for advanced mobile service.
  • Seamless Evolution path.
  • Quick paging channel operation.
  • Reverse link gated transmission.
  • Superior voice quality.
  • High-speed broadband data connectivity. 
  • Improve securities and privacy.
  • Multi-mode, multiband global roaming features. 

CDMA 2000

What is CDMA 2000? 

Before we learn about CDMA 2000 first let us learn about what is full form of CDMA. CDMA 2000 is code division multiple access version of the IMT-2000 standard developed by the International Telecommunication Union. 

 CDMA 2000 also known as the IMT-CDMA multi-carrier or the 1xRTT.

 Overview :
  • CDMA 2000 is a high data rate upgrade path for current users of 2G and 2.5G CDMA standard. It is a unique radio and network access system that is part of the international telecommunication called 2000. It is called a 3G standard.
  • CDMA 2000 allows the basically same spectrum, bandwidth, RF equipment, and air interface framework to be used at each station.
  • The first CDMA air interface CDMA 2000  with 1 × RTT (Radio transmission technology language) indicates that a single 1.25 MHz radio channel used.
  • CDMA 1x support data rate up to 307 kbps for a single user in packet mode. It can provide a throughput rate of up to 144 kbps depending on the propagation conditions.
  • CDMA 1xEV as an also part of IMT 2000. Its provide CDMA carrier with the option of installing radio channel with data only or data and voice only.
  • CDMA 2000 3xRTT standard is used for three adjacent 1.25 MHz radio channel. It can be used together to provide instantaneous packet data.
  • This article gives information about Feature, advantages, application of CDMA 2000 to gives more information about CDMA 2000.
A feature of CDMA 2000 :  
  • Support high-speed data service.
  • It is a global standard.
  • It has the flexibility for evolution.
  • It has improved spectrum efficiency.
  • Support advance mobile service.
  • Leading performance.
  • Industry-leading performance
  • Device selection
  • Flexible migration path
  • Flexible network architecture
  • New common channel structure and operation
  • Ubiquitous idle time operation
  • Global roaming and multi-mode, multiband devices
  • Flexible spectral allocation and efficient use of spectrum
Let us check is out the application of CDMA 2000 given below :

 Application of CDMA 2000 :
  • It is developed for both mobile radio and cordless application
  • Wireless internet
  • Location-based services
  • Wireless email
  • Telemetry
  • Wireless telecommunication
  • Longer standby battery life
  • Wireless commerce

Feature of WiFi

Wi-Fi stands for Wireless fidelity is an alternative to wired technology that is commonly used for connecting devices in wireless mode. There is numerous application of Wi-Fi in different areas because of some useful feature of Wi-Fi. So now let us check the features of Wi-Fi one by one below :

 Features of Wi-Fi :
  • While using Wi-Fi there is no limitation
  • Faster and secure
  • Unmatched mobility
  • Fortress technology
  • No need for cabling
  • Secure interment connection for feature
  • It's convenient and everywhere
  • It is a scalable and robust system
  • Great power consumption
  • The easy way of network installation
  • The configuration of the device is very easy
  • If we are nearer to Wi-Fi hotspot  network then you will automatically connect internet 

Advantages and disadvantages of gate turnoff thyristor

Advantages of GTO :
  • Fast and efficient turn-off.
  • High efficiency.
  • Exhibits low gate currents.
  • Faster turn OFF permitting high switching frequencies.
  • High blocking voltage capabilities.
  • High over current capabilities.
  • High capability of blocking voltage.
  • Better for static and dynamic dv/dt capabilities.
  • It does not need to require the communication circuit, hence it reduced the size, weight, and cost.
Disadvantages of GTO :
  • Holding current and magnitude of latching current is more.
  • Gate drive circuit losses are more.
  • While GTO on state voltage drop is more.
  • Triggering gate current is much higher than that required for normal SCR.

Advantages and disadvantages of uninterruptible power supplies

The term UPS full form Uninterruptible Power Supplies typically used to protect as data centers, telecommunication, computers, and also have some other electrical equipment where unexpected power disruption could cause injuries, serious business, or data losses. This article gives information about the advantages and disadvantages of a UPS device to know more about the UPS device.

 Advantages of Uninterruptible power supplies :
  • Emergency power supply
  • Maintain battery life
  • Provide surge protection
  • Protect some uncertain data loss
  • Use gives a huge power back in the industries
  • Reliable power source
  • Trusted power solution provider
  • Uncertain data loss can be prevented
  • Protect the voltage-sensitive device from bad electricity
Disadvantages of Uninterruptible power supplies :
  • Maintain cost is difficult
  • The startup cost is too much high
  • Commercial uses require a large number of batteries
There are just some the industries that can benefit from UPS system :
  • Data and call centers devices
  • Universities
  • Telecommunication and cable companies
  • Electronics manufactures
  • Bank
  • Hospital and medical centers
  • TV station
  • Utility companies
  • Production-based manufactures
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