D686 Operating Systems for Computer Scientists - Set 4 - Part 2

Correct Answer: Adaptive sampling

Adaptive sampling adjusts measurement frequency based on activity levels, sampling more during exercise while reducing frequency during rest, optimizing battery life without sacrificing accuracy significantly.
Option a is incorrect because constant sampling drains batteries quickly making multi-day operation impossible; wearables need intelligent power management for practical usability periods required typically.
Option c is incorrect because random checks miss important health events and provide inconsistent data quality; health monitoring needs systematic not random sampling approaches for reliability.
Option d is incorrect because manual activation defeats continuous monitoring purpose; fitness tracking needs automatic operation to capture all activity throughout days comprehensively recorded.

Correct Answer: Process isolation

Process isolation runs each match in separate processes with independent memory spaces, containing crashes and preventing cascading failures across multiple concurrent game sessions effectively maintained.
Option a is incorrect because monolithic servers share single process space where one crash affects all matches, causing massive disruption to concurrent gaming sessions simultaneously occurring.
Option c is incorrect because shared memory creates dependencies between matches where corruption in one match's data could affect others sharing the same memory regions.
Option d is incorrect because global state creates coupling between matches where problems in one game instance propagate to others through shared state dependencies existing.

Correct Answer: Template hashing

Template hashing converts facial features to irreversible mathematical representations, enabling recognition without storing identifiable images, balancing security needs with privacy protection requirements effectively implemented practically.
Option a is incorrect because image storage keeps identifiable photos raising privacy concerns and regulatory issues when storing biometric data of individuals without consent potentially.
Option c is incorrect because video recording captures full footage containing identifying information, maximizing privacy risks rather than protecting individual privacy as required increasingly.
Option d is incorrect because picture compression reduces file size but maintains visual information; compressed images still contain identifiable facial features violating privacy requirements potentially present.

Correct Answer: Dynamic path planning

Dynamic path planning continuously calculates collision-free routes for all robots simultaneously, maximizing efficiency while preventing interference through real-time coordination algorithms operating continuously throughout operations performed.
Option a is incorrect because fixed paths limit flexibility and create bottlenecks when multiple robots need the same route, reducing warehouse throughput significantly potentially observed practically.
Option c is incorrect because random movement causes unpredictable collisions and inefficient operations; warehouses need coordinated not chaotic robot movement for productivity and safety fundamentally.
Option d is incorrect because sequential operation where robots wait turns dramatically reduces throughput; parallel operation with collision avoidance maximizes efficiency in automated warehouses significantly.

Correct Answer: Multi-sensor fusion

Multi-sensor fusion integrates cameras, loop detectors, and radar data providing comprehensive traffic awareness, enabling intelligent signal timing optimization beyond single sensor capabilities alone potentially achieved.
Option a is incorrect because single detection methods miss vehicles or provide incomplete information; comprehensive traffic management needs multiple data sources for accuracy and reliability fundamentally.
Option c is incorrect because timer-based control ignores actual traffic conditions, causing unnecessary delays when traffic patterns don't match predetermined timing schedules programmed initially originally.
Option d is incorrect because manual override requires human intervention impractical for continuous optimization; smart systems need automatic adaptation to changing traffic patterns continuously observed.

Correct Answer: Peer-assisted delivery

Peer-assisted delivery allows users to share stream segments with nearby peers, reducing server bandwidth requirements while maintaining quality through distributed content delivery effectively implemented practically achieved.
Option a is incorrect because individual streams multiply server load linearly with users, becoming unsustainable for thousands of simultaneous viewers accessing educational content concurrently happening regularly.
Option c is incorrect because server multiplication increases infrastructure costs; peer assistance achieves scaling without proportional server investment using existing user resources available inherently present.
Option d is incorrect because bandwidth limiting degrades quality for all users rather than efficiently distributing load; peer assistance maintains quality while reducing server requirements significantly.

Correct Answer: Predictive scheduling

Predictive scheduling learns occupancy patterns to pre-condition spaces before arrival and reduce conditioning when empty, optimizing comfort while minimizing energy consumption effectively achieved through learning algorithms.
Option a is incorrect because constant temperature wastes energy conditioning empty spaces; intelligent systems should adapt to actual occupancy not maintain fixed conditions unnecessarily continuously operating.
Option c is incorrect because manual adjustment requires human intervention and can't anticipate needs; automation should predict and adjust without constant human input required repeatedly needed.
Option d is incorrect because random cycling doesn't correlate with occupancy causing discomfort and inefficiency; HVAC control needs intelligent not arbitrary scheduling for effectiveness fundamentally required.

Correct Answer: Proximity-based matching

Proximity-based matching considers distance, direction, and availability to optimize assignments, reducing wait times and maximizing driver efficiency through intelligent pairing algorithms operating continuously in real-time.
Option a is incorrect because first-come matching ignores geography creating inefficient routes where drivers pass better matches to serve earlier requests reducing overall system efficiency.
Option c is incorrect because random pairing ignores location and timing creating terrible efficiency; ride-sharing needs intelligent not arbitrary matching for viable service delivery practically.
Option d is incorrect because batch assignment delays matches accumulating requests; real-time matching provides faster service than waiting for batch processing to complete periodically.

Correct Answer: Network time protocol

Network time protocol synchronizes all equipment to microsecond precision ensuring experimental data from different instruments aligns correctly for valid scientific analysis and reproducible results consistently.
Option a is incorrect because manual synchronization introduces human error and drift over time; scientific equipment needs automated precise synchronization for valid experimental data collected accurately.
Option c is incorrect because local clocks drift independently causing timestamp misalignment; coordinated experiments need synchronized not independent timing for data correlation required scientifically necessarily.
Option d is incorrect because approximate timing invalidates experimental results where precise correlation matters; scientific instruments need exact not approximate synchronization for validity fundamentally required absolutely.

Correct Answer: Adaptive bitrate streaming

Adaptive bitrate streaming continuously adjusts video quality matching available bandwidth, prioritizing continuous communication over perfect quality when network conditions become challenging maintaining usability throughout conversations effectively.
Option a is incorrect because fixed quality causes freezing or dropping when bandwidth insufficient; adaptive systems maintain continuity by adjusting quality to match conditions dynamically present.
Option c is incorrect because connection termination disrupts communication entirely; the goal is maintaining conversation despite network challenges not giving up when difficulties arise temporarily.
Option d is incorrect because audio-only mode eliminates video entirely; adaptive streaming maintains video at reduced quality preserving visual communication when possible despite limitations existing.

Correct Answer: Hardware security modules

Hardware security modules store keys in tamper-resistant hardware inaccessible to software, protecting cryptocurrency even when operating systems are completely compromised by malware infections present potentially.
Option a is incorrect because software encryption remains vulnerable to malware with system access; compromised OS can access software-based protections defeating security measures implemented programmatically essentially.
Option c is incorrect because password protection in compromised systems offers no security; malware can capture passwords or bypass software-based authentication mechanisms easily when present systematically.
Option d is incorrect because file hiding provides no security against malware with system access; hidden files are easily discovered by competent malware searching systematically throughout.

Correct Answer: Local preprocessing

Local preprocessing analyzes sensor data on-site, transmitting only significant events and summaries, dramatically reducing cellular costs while maintaining agricultural monitoring effectiveness continuously throughout growing seasons.
Option a is incorrect because cloud-only processing requires transmitting all raw data consuming expensive cellular bandwidth for routine readings that could be processed locally first efficiently.
Option c is incorrect because raw transmission sends unprocessed data wasting bandwidth on normal readings; preprocessing identifies important changes worth transmitting over cellular networks selectively intelligently.
Option d is incorrect because manual logging requires field visits missing real-time monitoring benefits; automated systems need continuous not periodic manual data collection for effectiveness fundamentally.

Correct Answer: Virtual reservations

Virtual reservations assign return times allowing guests to enjoy other attractions instead of standing in lines, improving satisfaction while managing capacity effectively throughout operating hours systematically.
Option a is incorrect because physical lines waste guest time standing unproductively; virtual systems let visitors experience more attractions during their limited park visit time available.
Option c is incorrect because random selection creates uncertainty and unfairness; guests need predictable access times for planning their day effectively throughout park visits made purposefully.
Option d is incorrect because unlimited access creates overcrowding at popular attractions; controlled access through reservations ensures manageable crowds and reasonable wait times for everyone visiting.

Correct Answer: Delta compression

Delta compression transmits only position changes exceeding thresholds, eliminating redundant updates when vehicles are stationary or moving predictably, significantly reducing data transmission costs effectively achieved practically.
Option a is incorrect because continuous streaming sends data constantly even when vehicles aren't moving, wasting bandwidth on redundant identical position reports unnecessarily transmitted repeatedly continuously.
Option c is incorrect because full updates retransmit complete information repeatedly; delta compression sends only changes reducing redundancy in fleet tracking data transmitted over networks efficiently.
Option d is incorrect because random sampling might miss important position changes; fleet management needs systematic not random position tracking for accurate vehicle monitoring continuously required.

Correct Answer: Motion detection

Motion detection sensors trigger displays when visitors approach, providing engaging experiences while conserving power during empty periods, balancing interactivity with energy efficiency effectively throughout museum operations.
Option a is incorrect because always-on displays waste power when no visitors present; museums need intelligent activation to reduce energy consumption during quiet periods significantly occurring.
Option c is incorrect because scheduled activation might miss visitors outside expected times; exhibits should respond to actual presence not predetermined schedules for engagement effectiveness maximized.
Option d is incorrect because manual buttons require visitor action reducing engagement; interactive exhibits should activate automatically creating seamless immersive experiences for visitors approaching naturally effortlessly.

Correct Answer: Priority queuing

Priority queuing places emergency communications ahead of regular traffic ensuring critical calls connect even when networks are congested, potentially saving lives through guaranteed access during emergencies.
Option a is incorrect because equal priority treats emergency and regular calls identically, potentially blocking critical communications during network congestion when priority is needed most urgently.
Option c is incorrect because random selection could delay emergency calls; life-critical communications need guaranteed not chance-based priority for reliable emergency response system operations fundamentally.
Option d is incorrect because first-come service could queue emergencies behind routine calls; emergency systems need priority not sequential processing for critical communications handling required absolutely necessarily.

Correct Answer: Distributed processing

Distributed processing parallelizes content moderation across multiple servers, enabling platforms to handle millions of uploads through horizontal scaling rather than single-point processing bottlenecks potentially occurring otherwise.
Option a is incorrect because single servers create bottlenecks unable to handle social media volumes; platforms need distributed not centralized processing for scale requirements fundamentally necessary essentially.
Option c is incorrect because manual review can't scale to millions of uploads; automated distributed systems are essential for platform-scale content moderation requirements practically needed absolutely.
Option d is incorrect because batch processing delays moderation allowing harmful content to spread; real-time distributed processing enables quick response to problematic uploads requiring immediate attention urgently.

Correct Answer: Progressive achievements

Progressive achievements provide escalating challenges and rewards based on user progress, maintaining engagement through personalized goals that adapt to fitness levels encouraging continued participation effectively sustained motivationally.
Option a is incorrect because fixed rewards become predictable and boring over time; progressive systems maintain interest through evolving challenges adapted to user improvement continuously developing progressively.
Option c is incorrect because random prizes don't reward effort consistently potentially frustrating users; achievement systems should recognize progress not chance for motivational effectiveness fundamentally required necessarily.
Option d is incorrect because time-based unlocks ignore actual activity levels; fitness apps should reward exercise completed not time elapsed for genuine health motivation effectively delivered appropriately.

Correct Answer: Work distribution

Work distribution algorithms balance orders across available stations considering current load and capabilities, preventing bottlenecks while maximizing kitchen throughput during peak service periods effectively managed dynamically continuously.
Option a is incorrect because single queues create bottlenecks at busy stations while others remain idle; intelligent distribution utilizes all available capacity efficiently throughout service periods comprehensively.
Option c is incorrect because random assignment ignores station capabilities and current load potentially overwhelming some stations while others remain underutilized inefficiently creating imbalances unnecessarily problematically occurring.
Option d is incorrect because sequential processing doesn't distribute load just processes in order; peak periods need parallel not serial processing for timely service delivery practically required.

Correct Answer: Sensor redundancy

Sensor redundancy deploys multiple sensors for critical measurements, allowing systems to continue operating accurately when individual sensors fail through voting and validation mechanisms implemented effectively reliably.
Option a is incorrect because single sensors create single failure points stopping data collection when they malfunction; weather monitoring needs reliability through redundancy not single points potentially failing.
Option c is incorrect because manual reading requires human presence impractical for remote weather stations; automated systems need self-sufficient operation in remote locations continuously operating autonomously necessarily.
Option d is incorrect because estimated values reduce accuracy potentially missing dangerous weather events; meteorological systems need actual not approximated measurements for safety warnings critically important absolutely.