Mixed Deck — All NCEES Topics Flashcards

In the NCEES PE Chemical exam, what is the purpose of 'layer of protection analysis (LOPA)' in process safety?

Answer: To semi-quantitatively estimate the frequency of an undesired event and verify that independent protection layers are adequate to meet risk tolerances

LOPA evaluates each independent protection layer (IPL) and their probability of failure on demand to determine if the combination of safeguards reduces risk to an acceptable level.

In NCEES PE Electrical problems, the full-load efficiency of a transformer is calculated as:

Answer: η = Output power / (Output power + Total losses)

Transformer efficiency η = Pout/(Pout + Total losses) = Pout/(Pout + P_core + P_copper).

In the NCEES PE Environmental exam, which metric is used to design disinfection systems using the CT concept?

Answer: The product of disinfectant concentration (C) and contact time (T) required for a specified log inactivation of pathogens

CT (concentration × time) is the fundamental design metric for chemical disinfection; regulators specify CT values (in mg/L·min) required to achieve target log-inactivation of Giardia, Cryptosporidium, and viruses.

Which NCEES PE Structural topic involves checking that a retaining wall does not overturn about its toe?

Answer: Overturning stability check

The overturning stability check ensures the stabilizing moment from wall weight exceeds the overturning moment from retained soil pressure.

In NCEES PE Electrical practice, the resonant frequency of a series RLC circuit is:

Answer: f₀ = 1/(2π√LC)

Resonant frequency f₀ = 1/(2π√LC): at resonance, inductive and capacitive reactances cancel.

On the NCEES PE Electrical exam, the three-phase apparent power for a balanced system is:

Answer: S = √3 × VL × IL

Three-phase apparent power S = √3 × VL × IL, where VL and IL are line voltage and line current respectively.

Graphite is a main component in many:

Answer: Composites

Explanation: Graphite is commonly used as a reinforcing filler material in composites. Composites are materials composed of two or more distinct phases, typically a matrix and a reinforcement, combined to achieve specific mechanical or physical properties. Graphite, due to its excellent strength and lightweight properties, is often incorporated into composites to enhance their structural integrity and performance. Ceramics are typically non-metallic, inorganic compounds; plastics are organic polymers; and alloys are mixtures of two or more elements, none of which typically include graphite as a main component.

Injection molding is used predominantly in:

Answer: Thermoplastic Processes

Explanation: Injection molding is a manufacturing process primarily used for thermoplastics. Thermoplastics are a type of polymer that becomes pliable or moldable above a specific temperature and solidifies upon cooling. In injection molding, the thermoplastic material is heated to its melting point and injected under pressure into a mold cavity, where it cools and solidifies to form the desired shape. This process is widely used for producing plastic parts and components in various industries due to its efficiency, repeatability, and ability to create complex shapes with high precision.

Included angles in a precise traverse are determined by setting the vernier

Answer: Indefinite contour gradients are possible

This question appears to have mismatched options for the given prompt. Assuming the question intended to ask about contour gradients based on the correct answer, 'Indefinite contour gradients are possible' is correct because a contour line represents points of equal elevation. The gradient (slope) at any point on a contour is perpendicular to the contour itself, and its steepness can vary significantly along the contour's path, depending on the terrain and proximity to other contours.

In the NCEES PE Chemical exam, what is the 'Arrhenius equation' used to describe?

Answer: The exponential dependence of reaction rate constant on temperature: k = A × exp(−Ea/RT)

The Arrhenius equation k = A·exp(−Ea/RT) quantifies how the rate constant increases exponentially with temperature, where Ea is activation energy and A is the pre-exponential frequency factor.

In NCEES PE Structural practice, shear lag in a bolted tension member is accounted for by applying which reduction factor?

Answer: Reduction factor U

The shear lag factor U reduces the net effective area of a tension member when not all elements are connected.

On the NCEES PE Mechanical exam, what does 'fatigue limit' (endurance limit) represent for a steel component?

Answer: The stress amplitude below which a material can theoretically withstand infinite load cycles without failure

The endurance limit (Se) is the stress amplitude below which a ferrous material can endure an essentially unlimited number of loading cycles without fatigue failure.

On the NCEES PE Environmental exam, what is the 'solids retention time (SRT)' or sludge age in an activated sludge system?

Answer: The average time microorganisms remain in the system before being wasted, controlling biological process performance

SRT (= total mass of VSS in system / daily VSS wasted) controls the microbial community — longer SRT enables nitrification, while shorter SRT may wash out slow-growing organisms.

The term for electrons in the outer orbit is

Answer: valences

Valence electrons are the electrons located in the outermost electron shell of an atom. These electrons are critically important because they determine an atom's chemical properties and its ability to form chemical bonds with other atoms. The number of valence electrons dictates an element's reactivity and how it will interact in chemical reactions.

In the NCEES PE Mechanical exam, what is the purpose of the 'Miner's rule' in fatigue analysis?

Answer: To linearly accumulate damage fractions from variable amplitude stress cycles

Miner's rule (cumulative damage theory) sums the ratios ni/Ni for each stress level, predicting fatigue failure when the sum reaches 1.0.

Grid lines are perpendicular to

Answer: Line representing the central true meridian of the grid

In a grid coordinate system, grid lines are established to create a rectangular framework for surveying and mapping. The Y-axis of this grid is typically aligned with a designated central true meridian. Consequently, the X-axis (or the east-west grid lines) are constructed to be precisely perpendicular to this central true meridian, forming the orthogonal grid system.

For the NCEES PE Mechanical exam, which dimensionless number characterizes the ratio of inertial forces to viscous forces in fluid flow?

Answer: Reynolds number

The Reynolds number (Re = ρVD/μ) compares inertial to viscous forces and determines whether flow is laminar or turbulent.

In the NCEES PE Electrical exam, what does 'voltage regulation' of a transformer measure?

Answer: The percentage change in secondary voltage from no-load to full-load

Voltage regulation = (VNL - VFL)/VFL × 100%, measuring how much the secondary terminal voltage drops from no-load to full-load condition.

For the NCEES PE Electrical exam, Kirchhoff's Voltage Law (KVL) states that:

Answer: The algebraic sum of voltages around any closed loop equals zero

KVL: the sum of all voltage rises and drops around any closed loop equals zero, reflecting conservation of energy.

For the NCEES PE Geotechnical exam, a flow net is used to determine:

Answer: Seepage quantity and pore pressure distribution around structures

Flow nets graphically represent seepage through soil, allowing computation of flow quantity (Q = KH × Nf/Nd) and pore pressure heads.