D686 Operating Systems for Computer Scientists - Set 5 - Part 1

Correct Answer: Error-correcting codes

Error-correcting codes detect and fix bit errors from radiation, maintaining data integrity in space environments where cosmic rays constantly bombard computer memory systems continuously.
Option a is incorrect because data encryption protects confidentiality not bit errors; radiation flips bits regardless of encryption status requiring error correction not security measures fundamentally.
Option c is incorrect because file compression reduces size but doesn't protect against bit flips; compressed data becomes more vulnerable to corruption from radiation-induced errors occurring.
Option d is incorrect because access control manages permissions not hardware errors; cosmic ray protection needs error correction not authentication mechanisms for data integrity preservation.

Correct Answer: Synchronization buffering

Synchronization buffering delays faster streams until slower ones catch up, maintaining audio-video alignment essential for natural viewing experiences without distracting synchronization errors occurring during playback.
Option a is incorrect because single buffers can't handle different stream rates; synchronization needs independent buffers for audio and video with coordination mechanisms between them implemented.
Option c is incorrect because random buffering would destroy synchronization entirely; broadcast systems need precise not arbitrary buffering for maintaining audio-video alignment consistently throughout transmission.
Option d is incorrect because no buffering causes immediate desynchronization when processing speeds differ; proper buffering is essential for synchronized multimedia playback experiences delivered professionally.

Correct Answer: Mechanical failsafe

Mechanical failsafe locks default to locked position without power, ensuring security even during electrical failures, preventing escapes when electronic systems fail unexpectedly during emergencies.
Option a is incorrect because electronic locks might unlock during power failures if not properly designed; security requires mechanical backup not purely electronic systems for reliability.
Option c is incorrect because powered magnets release when electricity fails potentially opening doors; fail-secure systems must lock not release during power loss occurring unexpectedly.
Option d is incorrect because remote control requires power and communication; security systems need local mechanical operation not remote dependency during failure conditions potentially arising.

Correct Answer: Format migration

Format migration periodically converts data to current standards before old formats become unreadable, ensuring long-term preservation as technology evolves over archaeological timescales required for historical preservation.
Option a is incorrect because single formats become obsolete and unreadable over decades; preservation requires active migration not passive storage for long-term accessibility guaranteed effectively.
Option c is incorrect because original media deteriorates and readers disappear over time; archaeological data needs format updates not reliance on obsolete technology becoming unavailable eventually.
Option d is incorrect because paper backup isn't practical for large databases and degrades over time; digital preservation needs format migration not physical media for longevity.

Correct Answer: Time synchronization protocol

Time synchronization protocol coordinates all devices to microsecond precision, ensuring musicians see measure changes simultaneously essential for coordinated performance despite network latencies inherently present in systems.
Option a is incorrect because best effort delivery doesn't guarantee timing; orchestras need precise not approximate synchronization for coordinated musical performance requiring exact timing throughout performances.
Option c is incorrect because random timing would create chaos with musicians on different measures; coordinated performance requires precise not arbitrary synchronization for musical coherence fundamentally necessary.
Option d is incorrect because local clocks drift causing gradual desynchronization during performances; orchestras need continuous network synchronization not independent timekeeping for coordination throughout concerts performed.

Correct Answer: Byzantine consensus

Byzantine consensus requires agreement among multiple systems before executing critical commands, preventing single failures or compromised systems from causing catastrophic reactor events potentially occurring otherwise.
Option a is incorrect because single authority creates dangerous single point of failure; nuclear safety requires distributed not centralized decision making for critical operations fundamentally necessary.
Option c is incorrect because random selection ignores safety considerations entirely; reactor control needs verified consensus not arbitrary choices for safety-critical decisions absolutely required necessarily mandated.
Option d is incorrect because first responder allows single system to make critical decisions; nuclear safety demands multiple system agreement not individual authority for catastrophic prevention required.

Correct Answer: Adaptive compression

Adaptive compression adjusts algorithms based on data characteristics and channel conditions, maximizing information throughput through severely bandwidth-limited underwater acoustic channels available for submarine communications necessarily utilized.
Option a is incorrect because no compression wastes precious underwater bandwidth; acoustic channels have such limited capacity that compression is essential for practical communication underwater fundamentally required.
Option c is incorrect because fixed ratios can't optimize for varying data types and conditions; underwater communication needs adaptive not static compression for efficiency maximization continuously needed.
Option d is incorrect because random sampling loses critical information unpredictably; submarine communications need reliable not probabilistic data transfer for operational safety and effectiveness required absolutely.

Correct Answer: Trend analysis

Trend analysis identifies gradual temperature and humidity shifts before reaching damaging levels, enabling preventive action protecting priceless artifacts from environmental deterioration occurring slowly over time.
Option a is incorrect because reactive alarms trigger after damage thresholds are crossed potentially too late; artifact protection needs predictive not reactive monitoring for preservation effectiveness maximized.
Option c is incorrect because random checks miss developing problems between samples; continuous trend monitoring catches gradual changes that periodic checks might miss entirely potentially.
Option d is incorrect because visual inspection detects existing damage not environmental conditions developing; museums need environmental not visual monitoring for preventive conservation measures implemented proactively.

Correct Answer: Distributed sensors

Distributed sensors detect faster primary waves at multiple locations, triangulating epicenters and providing crucial seconds of warning before slower destructive secondary waves arrive at populated areas.
Option a is incorrect because single sensors can't determine direction or distance quickly enough; early warning needs multiple sensors for rapid epicenter location and timing calculations.
Option c is incorrect because satellite monitoring has too much latency for seconds-critical warnings; ground-based sensors provide immediate detection that space-based systems cannot match temporally.
Option d is incorrect because manual observation is far too slow for early warning; automated sensor networks provide the split-second detection needed for effective warnings practically.

Correct Answer: Atomic exchange

Atomic exchange protocols guarantee all-or-nothing execution where trades either complete fully or rollback entirely, preventing scenarios where one party loses assets without receiving agreed compensation.
Option a is incorrect because sequential transfers risk one party not completing their side after receiving assets; atomic swaps need simultaneous not ordered execution for fairness.
Option c is incorrect because partial completion leaves trades in inconsistent states potentially causing losses; exchanges need complete not partial transaction execution for integrity fundamentally required.
Option d is incorrect because manual verification introduces delays and human error; high-volume exchanges need automated atomic guarantees not manual processes for reliability and scale.

Correct Answer: Coordinated control

Coordinated control adjusts individual turbine parameters considering wake effects on downwind turbines, optimizing total farm output rather than individual turbine performance maximization independently attempted unsuccessfully otherwise.
Option a is incorrect because independent operation causes downstream turbines to underperform due to turbulent wakes; wind farms need coordination not isolation for optimal generation collectively achieved.
Option c is incorrect because random positioning would create chaotic airflow patterns reducing efficiency; wind farms need intelligent not arbitrary control for power maximization systematically required fundamentally.
Option d is incorrect because fixed angles can't adapt to changing wind conditions; dynamic coordination optimizes for current conditions unlike static configurations limiting adaptation possibilities significantly.

Correct Answer: Predictive analytics

Predictive analytics forecasts discharge patterns and emergency arrival rates, enabling proactive bed management that reduces waiting while maintaining availability for urgent cases requiring immediate admission necessarily.
Option a is incorrect because manual tracking reacts to current state without anticipating future needs; hospitals need predictive not reactive management for optimal patient flow throughout.
Option c is incorrect because first-come assignment ignores medical priority and predicted availability; bed management needs intelligent not sequential allocation for medical effectiveness and efficiency maximized.
Option d is incorrect because random allocation disregards medical needs and efficiency; hospitals require systematic not arbitrary bed assignment for patient care optimization fundamentally required essentially.

Correct Answer: Pattern recognition

Pattern recognition algorithms identify characteristic signatures of cosmic sources while filtering human-made interference, enabling astronomical observation despite increasing radio frequency pollution from terrestrial sources continuously present.
Option a is incorrect because amplification increases all signals including interference; telescopes need selective not universal amplification for distinguishing cosmic from terrestrial signals effectively throughout observations.
Option c is incorrect because signal blocking might eliminate astronomical signals along with interference; telescopes need intelligent filtering not blanket blocking for scientific observation capabilities preserved.
Option d is incorrect because volume increase amplifies noise with signals providing no discrimination; radio astronomy needs pattern analysis not simple amplification for signal identification required.

Correct Answer: Integrated navigation

Integrated navigation fuses multiple sensor inputs compensating for individual sensor limitations, enabling accurate positioning in GPS-denied underwater environments where traditional navigation fails completely without alternatives available.
Option a is incorrect because visual navigation is impossible in deep-sea darkness; underwater vehicles need non-visual sensors for navigation in lightless environments necessarily present at depth.
Option c is incorrect because surface tracking signals don't penetrate deep water; submersibles need onboard sensor fusion not surface-dependent navigation for deep-sea exploration autonomously conducted effectively.
Option d is incorrect because manual control is impractical with communication delays and limited visibility; deep-sea vehicles need autonomous not human-controlled navigation for effective exploration capabilities.

Correct Answer: Trend prediction

Trend prediction algorithms analyze multiple data streams identifying pattern changes indicating emerging fashions, enabling retailers to stock trending items before competitors recognize new style movements.
Option a is incorrect because historical analysis looks backward missing emerging trends; fashion needs forward-looking not retrospective analysis for competitive advantage in rapidly changing markets fundamentally.
Option c is incorrect because random guessing ignores available data patterns; successful retail needs data-driven not arbitrary predictions for inventory decisions affecting profitability significantly throughout seasons.
Option d is incorrect because manual selection can't process vast data volumes quickly enough; trend identification needs automated not human analysis for timely market response required.

Correct Answer: Closed-loop control

Closed-loop control continuously measures actual position against desired position, automatically compensating for disturbances maintaining nanometer precision despite environmental variations affecting manufacturing equipment continuously throughout production processes.
Option a is incorrect because open-loop control can't correct for disturbances after commands are sent; precision manufacturing needs feedback not blind control for accuracy maintenance required.
Option c is incorrect because manual adjustment is too slow and imprecise for nanometer accuracy; automated feedback control provides speed and precision humans cannot achieve practically.
Option d is incorrect because fixed positioning ignores thermal and vibration effects; precision manufacturing needs active not passive position control for accuracy requirements met consistently throughout.

Correct Answer: Write-once storage

Write-once storage physically prevents alteration after recording, guaranteeing document authenticity for legal purposes where tampering could undermine government accountability and judicial proceedings requiring evidence integrity.
Option a is incorrect because passwords can be compromised allowing modification; legal archives need physical not logical protection for absolute document authenticity guarantees required legally mandated.
Option c is incorrect because encryption protects confidentiality not immutability; encrypted files can still be modified or deleted compromising legal evidence integrity potentially undermining justice.
Option d is incorrect because hidden files remain modifiable by those with access; government records need immutable not concealed storage for legal authenticity requirements absolutely necessary.

Correct Answer: Distributed locking

Distributed locking coordinates seat inventory across worldwide reservation systems, preventing double-booking by ensuring exclusive access during purchase transactions regardless of booking channel used globally simultaneously.
Option a is incorrect because local locks don't coordinate between different booking systems globally; airlines need distributed not isolated locking for preventing overbooking across channels worldwide.
Option c is incorrect because no locking allows simultaneous sales of same seats causing overbooking; reservation systems need coordinated locking for inventory integrity maintained consistently throughout.
Option d is incorrect because time-based locking might expire during legitimate transactions; airline bookings need transaction-based not temporal locking for reliable seat inventory management required.

Correct Answer: Autonomous navigation

Autonomous navigation enables rovers to identify and avoid hazards independently, essential when communication delays make real-time control impossible across interplanetary distances requiring independent operation capabilities fundamentally necessary.
Option a is incorrect because remote control is impossible with multi-minute delays between planets; rovers need autonomy not Earth-based control for practical exploration operations conducted effectively.
Option c is incorrect because predetermined paths can't account for unexpected obstacles discovered during exploration; rovers need adaptive not fixed navigation for unknown terrain encountered unexpectedly.
Option d is incorrect because random movement wastes limited power and risks damage; planetary exploration needs intelligent not arbitrary navigation for mission success absolutely required essentially.

Correct Answer: Parallel evaluation

Parallel evaluation distributes position analysis across multiple processors, exponentially increasing positions examined per second enabling deeper strategic analysis than sequential processing allows within time constraints.
Option a is incorrect because sequential analysis examines positions one at a time too slowly; competitive chess needs parallel not serial evaluation for sufficient depth within time limits.
Option c is incorrect because random selection ignores position quality producing terrible moves; chess requires systematic not arbitrary evaluation for competitive play at high levels required.
Option d is incorrect because single threading underutilizes modern multicore processors; chess engines need parallel not sequential processing for maximum analytical strength achievable with available hardware.