UAE Engineer Exam cheat sheet

Stress σ = F/A; strain ε = ΔL/L; elastic modulus E = σ/ε within the proportional limit.

Beam bending: σ = My/I, with maximum stress at the greatest distance y from the neutral axis.

Bernoulli (steady, incompressible, frictionless): p/γ + v²/2g + z = constant along a streamline.

Reynolds number Re = ρvD/μ; pipe flow is generally laminar below Re ≈ 2000 and turbulent above ≈ 4000.

Thermal expansion: ΔL = α·L·ΔT; linear α is roughly 12×10⁻⁶ /°C for steel and 23×10⁻⁶ /°C for aluminium.

Ohm's law V = IR; three-phase real power P = √3·V_L·I_L·cos φ.

Unit conversions: 1 bar = 100 kPa, 1 kgf ≈ 9.81 N, 1 kWh = 3.6 MJ, 1 hp ≈ 0.746 kW.

Quadratic roots: x = [−b ± √(b² − 4ac)] / 2a; the discriminant b² − 4ac gives the number of real roots.

Concrete characteristic strength fck is the 28-day cube strength exceeded by 95% of test results; design strength = 0.85·fck/γc in many codes.

Steel reinforcement: yield strength fy typically 420–500 MPa for deformed bars; minimum concrete cover depends on exposure class.

Transformer efficiency peaks when copper (I²R) losses equal core (iron) losses.

For a centrifugal pump, flow varies with speed N, head with N², and power with N³ (affinity laws).

HVAC sensible heat Q_s = 1.2 × airflow (m³/s) × ΔT (°C) in kW; latent heat depends on moisture difference.

Diesel/gas engine ideal cycle is the dual cycle; Otto cycle efficiency η = 1 − 1/r^(γ−1) with compression ratio r.

Corrosion control: cathodic protection, protective coatings, and material selection by galvanic series (avoid coupling dissimilar metals).

Circuit breakers are rated by interrupting capacity and trip curve; discrimination ensures only the nearest device trips.

Design factor (safety factor) = failure strength / allowable stress; allowable stress = strength / design factor.

Load combinations in limit-state design apply factored dead, live, wind, and seismic loads with separate factors and combinations.

Fatigue design uses S-N curves; endurance limit applies for steels below about 10⁶ cycles.

Finite element analysis: refine mesh where stress gradients are high; check convergence of results with mesh size.

Tolerance stack-up: worst-case = sum of tolerances; statistical (RSS) = √(sum of squared tolerances).

Buckling of a column: Euler load P_cr = π²EI/(KL)², where K depends on end conditions.

Reliability: system in series R = ΠRᵢ; parallel (redundant) system R = 1 − Π(1 − Rᵢ).

Design review stages: conceptual, preliminary, detailed, and verification/validation against requirements.

Codes set minimum requirements; standards are consensus technical documents; specifications are project-specific.

Common structural codes: ACI 318 (concrete), AISC 360 (steel), ASCE 7 (loads); Eurocodes EN 1990–1999 are the European equivalents.

Fire safety: NFPA 101 (Life Safety Code) and NFPA 13 (sprinklers); building codes classify occupancy and construction type.

Pressure equipment: ASME Boiler and Pressure Vessel Code; piping ASME B31 series.

Electrical installations: IEC 60364 / NEC NFPA 70; hazardous areas use IEC 60079 zone classification.

Compliance requires documented traceability from requirement to verification evidence (test reports, certificates).

Local authority having jurisdiction (AHJ) permits and inspections are legally required before occupancy.

Standards are updated periodically; always confirm the edition referenced by the contract.

Hierarchy of controls: elimination, substitution, engineering controls, administrative controls, then PPE.

Risk score = likelihood × severity; residual risk is assessed after controls are applied.

Confined space entry requires atmospheric testing (O₂ 19.5–23.5%), permit, attendant, and rescue plan.

Lockout/tagout (LOTO) isolates hazardous energy before maintenance; verify zero energy state.

Hazardous waste: cradle-to-grave responsibility; manifests track transport and disposal.

Noise exposure limit commonly 85 dBA over 8 hours; use hearing protection above the action level.

Environmental impact assessment (EIA) identifies significant impacts and mitigation before project approval.

Incident investigation (root cause analysis) aims at system causes, not blame; report near-misses too.

Present worth: PW = F/(1+i)ⁿ; annuity factor (P/A, i, n) = [(1+i)ⁿ − 1]/[i(1+i)ⁿ].

Net present value (NPV) > 0 means the project earns more than the discount rate; choose the highest NPV among alternatives.

Internal rate of return (IRR) is the discount rate at which NPV = 0; accept if IRR exceeds the hurdle rate.

Payback period = initial investment / annual net cash flow (simple, ignores time value).

Depreciation: straight-line = (cost − salvage)/life; declining balance applies a fixed rate to book value.

Critical path method (CPM): the critical path has zero total float; any delay there delays the project.

Earned value: CV = EV − AC, SV = EV − PV; CPI = EV/AC, SPI = EV/PV.

Break-even quantity = fixed costs / (unit price − unit variable cost).

Paramount obligation: protect public health, safety, and welfare above employer or client interests.

Competence rule: accept work only within one's competence; disclose limitations and seek specialist input.

Conflict of interest must be disclosed in writing; avoid accepting gifts that could influence judgment.

Confidentiality applies to client information; exceptions exist for legal requirements or public safety.

Sign and seal only work you prepared or directly supervised; do not seal work of others without review.

Report known violations to the appropriate authority when safety is at risk; retaliation protections vary by jurisdiction.

Sustainable development: minimize environmental impact and consider life-cycle consequences in design decisions.

Bribery and facilitation payments are prohibited; maintain accurate and truthful records and reports.