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How things work: engineering for everyday life
Engineering enrichment, not a qualification or ranked global top 100. All 100 families/616 objectives mapped; 155 lessons explain selected objectives. All 616 assessments, practical and safe-design claims OPEN; mastery unverified. Figures are fictional, not plant data, ratings or instructions. GPU: transactions, arithmetic intensity, launch overhead. Heat pumps: reversible bounds, capacity, backup, auxiliaries. Inverters: available/accepted input, conversion heat, active/reactive headroom; operation/backup unverified. Batteries: terminal energy, cutoff, auxiliaries, inventory cycles. Lead-acid: chemical ceilings/material access, no diagnosis. Generator: timed need, shaft/terminal, auxiliary/delivery; suitability/affordability unverified. Community solar: physical supply/bill credits; no contract, eligibility or backup guarantee. Titanium: atoms, inventory, selected energy; no lifecycle/purity claim. RO: salt/water, pressure, shaft/electric service. Steel: exclusive reduction paths, material/electric/selected-carbon accounts. CMOS: stored/supply/heat, events, leakage, timing. Routing: serialization, queues, propagation, endpoint ordering. Ultrasound: last-return versus sustained cycle, sampling. Diffusion: moments/time weighting, not fronts or properties. Selected models exclude full plant, lifecycle, clinical, product and practical approval. Remaining depth requires review; full assessed coverage not verified. Storage: logical granularity, memory and write budgets.
Where electricity begins
From sunlight to useful electricity
Why moving air can turn a generator
Water power: head, flow and the whole river
Nuclear electricity: fission heat and three separate routes
Combined-cycle turbines: useful exhaust, counted once
Geothermal power: heat flow, working fluid and net output
Biogas: microbes change material, equipment captures useful energy
Concentrating solar thermal: collect heat, then choose when to use it
Changing voltage without connecting the coils
High voltage: a smaller current for the same transfer
Distribution protection: sensing is not interruption
Solar inverter: a waveform is not a new energy source
A battery needs two different paths
Lead-acid batteries: charge, chemistry and the load
Pumped storage: time-shifting energy, not making it
Hydrogen: separate electrons from the ionic route
UPS: power continuity is an energy and capacity problem
Microgrid: an island needs a balanced local system
How an electric motor produces torque
Gears exchange speed for torque
The thin film that carries a machine
Hydraulic actuators: force, flow and the pump behind them
Compressed air is a spring as well as a supply
Four piston strokes make one engine cycle
Compression ignition: why compressing air comes before useful work
Recovering motion without creating energy
Refrigerators: moving heat through a cycle
More heat delivered than electricity used
Heat exchangers: recovering heat without mixing streams
The pan becomes the heater
LED light: recombination, colour and the complete lamp
Washing machines: cleaning motion, spin and the next appliance
Microwave heating: absorption is not inside-out cooking
Vacuum cleaners: pressure, flow and particle capture
Insulation: follow every path heat can take
Moving water takes a whole system
Water purification: barriers remove different things
Reverse osmosis: separating water and concentrating a remainder
Bridges: trace forces before judging strength
From rock to metal: two different jobs
Why titanium metal needs careful processing
From iron-bearing feedstocks to useful steel
Why the same steel can behave differently
Copper moves through a different form
Why stainless steel can still corrode
Making flat glass and controlling its stress
Concrete hardens through a chemical reaction
Why a small crack matters in a ceramic
A mould gives shape; a process gives properties
Fibre direction changes what stiffness means
Printing a shape is not the same as making a sound part
A cutter follows a reference, not the outline on a screen
A weld changes metal beyond the melted seam
Distillation separates through contact and return
A synthesis loop makes more than one pass count
A paper machine removes water without losing the sheet
Sorting materials means measuring more than appearance
Stored bits need a physical state that survives power loss
Optical fiber: encoding light and preserving a signal
Radio communication: symbols, carriers and a shared channel
GNSS: solving for position and a clock
Feedback control: error becomes action, with limits
From a switch to CMOS logic
From an idea to a chip layout
Why inspection and packaging matter
Where AI computation moves its data
Training and inference are different jobs
Why many computers need coordination
Power, heat and responsibility behind AI
Humidity control: temperature is not water content
Ventilation and filtration: a clean-air mass balance
Wi-Fi: useful data depends on shared airtime
Digital cameras: collecting light is different from amplifying it
Wastewater: follow the water, solids and oxygen demand
Water distribution: height, pressure and finite storage
Irrigation: account for water in the root zone
Reinforced concrete: why the steel position matters
Steam power: a returning fluid still needs heat rejection
Turbofan thrust: count both momentum streams
Wings: separate lift, force balance and rotational control
Traction lifts: counterweights reduce imbalance, not safety requirements
Ultrasound: an echo measures a journey, not a diagnosis
Pulse oximetry: a light ratio needs validated interpretation
X-ray and CT: a projection is not a complete picture
MRI: resonance, encoding and the limits of an image
ECG: a measured voltage is evidence, not a complete heart assessment
Dialysis: transport, separation and what a model cannot promise
Prosthetic mechanics: a spring returns energy; a powered actuator adds it
Sterilisation: reducing survival and preventing recontamination are different jobs
Cold chains: the payload temperature matters more than a reassuring display
Pasteurisation: a flow average cannot prove every parcel was treated
Railways: why low resistance still needs adhesion
Ship propulsion: momentum, reference frames and wake energy
Bicycle gearing: more torque comes with less speed
Traffic signals: arrivals, service and the cost of shared time
Harvesting machinery: separate grain and account for losses
Precision agriculture: an index is not a prescription
Flood management: storage changes timing, not conservation
Air-pollution monitoring: correlation is not agreement
Earthquake-resistant structures: response, period and limits
District heating: keep the water and energy accounts distinct
Graphene: structure, sheet resistance and the finished device
Why a loaded generator needs more shaft work
A reliable supply needs a repair plan
Solar power: rating, temperature and the hours that matter
Solar lifetime: evidence, cumulative energy and responsible decisions
Wind power: speed, torque and the cost of a control choice
Wind blades: cycles, material evidence and responsible service
Hydropower: net head, losses and the limits of an optimum
Hydropower: river allocation, damage evidence and lifecycle service
Steam power: enthalpy, state evidence and efficiency boundaries
Steam power: condenser resistance and useful heat over time
Nuclear energy: event scales, deposited energy and the output boundary
Residual heat: power, accumulated energy and the limits of a safety model
Gas turbines: internal work, irreversibility and the limits of optimisation
Exhaust recovery: terminal temperatures, exchanger evidence and useful service
Geothermal heat: finite-source work and the inlet-temperature trap
Geothermal reservoirs: thermal budgets, service and local evidence
Biogas yield: follow the material, not the wet tonnes
Biogas benefit: compare the alternative and count residual methane
Solar receivers: why a hotter cycle need not yield more electricity
Thermal storage: schedule useful service without counting energy twice
Transformers under load: an induced voltage is not the terminal voltage
Transformer choices: why a lower full-load loss can cost more energy
Three phases, two boundaries: accounting for useful power and line loss
Weather, stored heat and the evidence behind a transmission limit
Protection exposure: squaring an average hides the clearing history
Selective isolation: why a better outage average can look worse
Charge yield is not energy efficiency
Recycling yield meets an alloy-quality constraint
Why a pattern-transfer window can disappear
GPU work groups: why addresses determine memory traffic
![Original 2×2 matrix product [[19,22],[43,50]], conceptual data reuse, and a linear hypothetical roofline with ridge 100 operations/byte at 20 TFLOP/s. Points n = 128 at (21.33,4.27) and n = 1024 at (170.67,20); the table adds a fixed 0.20 ms to max(compute,memory). Ideal lower bounds, not measured performance or an exact small-matrix instruction count.](/assets/lesson-engineering37-arithmetic-intensity-v1.webp)
AI matrix work: reuse, arithmetic intensity and bounded throughput
Temperature lift: an energy balance is not a performance guarantee
Seasonal service: weight heat, capacity and backup rather than headline COP
Solar inverters: clipping is not conversion heat
One inverter limit, two services: active energy and reactive headroom
The same charge can deliver different useful energy
Round-trip efficiency needs a round trip
Charge counts reactions, not a pile of electrons
Why material present is not necessarily material usable
Electricity that reaches people when they need it
Community solar: two ledgers, one household
Titanium's magnesium loop: where material and energy accounts change
Desalination: pressure energy gets a second job
Iron before steel: feed choice and the accounting boundary
Count the charges: CMOS power, energy and deadlines
Packets take turns: routing, queues and why faster links still make you wait
An image takes many listens: ultrasound acquisition time and sampling tradeoffs
Atoms spread, not march: diffusion distance and the time budget
A full reservoir still needs enough head and flow
Why a small write can move more data