PE Agricultural flashcards
PE Agricultural · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Feed conversion ratio
- Feed conversion ratio equals total feed consumed divided by live-weight gain; lower values indicate more efficient conversion of feed into animal product.
- Crop water requirement
- Crop evapotranspiration equals reference evapotranspiration multiplied by the crop coefficient; irrigation requirement subtracts effective rainfall and allowable soil-water depletion from that value.
- Grain storage moisture
- Corn is typically stored safely near 13 to 15 percent moisture and soybeans near 11 to 13 percent; higher moisture raises mold growth and spoilage risk.
- HTST pasteurization
- High-temperature short-time pasteurization of milk commonly uses 72 degrees Celsius for 15 seconds; holding-tube and flow-diversion controls ensure every particle is treated.
- Seed rate calculation
- Seed rate equals target plant population divided by germination and purity fractions, then multiplied by seed weight per seed and adjusted for expected field emergence.
- Processing mass balance
- For a steady process with no accumulation, product mass equals feed mass times product yield; byproduct mass equals feed mass minus product mass.
- Conveyor capacity
- Conveyor volumetric capacity equals material cross-sectional area times belt speed times bulk density times fill factor; unit conversions must be consistent to obtain mass per time.
- D-value
- The D-value is the heating time at a specified temperature that reduces a microbial population by 90 percent, which is one decimal log reduction.
- z-value
- The z-value is the temperature change that changes the D-value by a factor of ten; it quantifies how strongly microbial lethality depends on temperature.
- F0 sterilization value
- F0 is equivalent heating time at 121 degrees Celsius referenced to a z-value of 10 degrees Celsius; a 12D Clostridium botulinum cook is a common low-acid food target.
- Michaelis-Menten kinetics
- Michaelis-Menten rate equals maximum rate times substrate concentration divided by Km plus substrate concentration; Km is the substrate concentration at half the maximum rate.
- Power-law fluid
- A power-law fluid has shear stress equal to consistency index times shear rate raised to the flow-behavior index; n below one indicates shear-thinning behavior.
- Biot number
- Biot number equals convective heat-transfer coefficient times characteristic length divided by thermal conductivity; it compares internal conduction resistance with surface convection resistance.
- Universal soil loss equation
- USLE predicts average annual soil loss as rainfall erosivity times soil erodibility times slope length-steepness, cover-management, and support-practice factors.
- Curve number runoff
- Runoff depth equals precipitation minus 0.2S squared divided by precipitation plus 0.8S; S is potential retention derived from the curve number.
- Water balance
- Storage change equals precipitation plus irrigation minus evapotranspiration, runoff, and deep percolation; a negative result indicates that stored water is being depleted.
- Darcy law
- Darcy law states groundwater discharge equals hydraulic conductivity times cross-sectional area times hydraulic gradient; flow moves from high to low hydraulic head.
- BOD decay
- BOD at time t equals ultimate BOD times one minus exponential of negative reaction rate constant times time; the rate constant is usually base e.
- Compost C:N ratio
- Active composting commonly starts with a carbon-to-nitrogen ratio near 25 to 30 to 1 and moisture near 50 to 60 percent by weight.
- Drawbar power
- Drawbar power equals drawbar force times travel speed; use newtons and meters per second to obtain watts, then divide by 745.7 for horsepower.
- Hydraulic cylinder force
- Hydraulic cylinder force equals system pressure times piston area; extension force uses bore area, while retraction force uses bore area minus rod area.
- Pump shaft power
- Pump shaft power equals fluid density times gravity times flow rate times head divided by pump efficiency; add motor efficiency to estimate electrical input power.
- Fan laws
- For geometrically similar fans at constant air density, flow varies with speed, pressure with speed squared, and power with speed cubed.
- Three-phase power
- Three-phase real power equals square root of three times line voltage times line current times power factor for a balanced load.
- Beam bending stress
- Bending stress equals bending moment times distance from the neutral axis divided by moment of inertia; maximum stress occurs at the extreme fiber.
- Effective field capacity
- Effective field capacity equals implement width times travel speed times field efficiency, with a unit constant converting the result to acres or hectares per hour.
- Critical path
- The critical path is the longest-duration path through a project network; its activities have zero total float and determine the project duration.
- PERT expected time
- PERT expected time equals optimistic plus four times most likely plus pessimistic, all divided by six; variance equals pessimistic minus optimistic divided by six squared.
- Net present value
- Net present value discounts all project cash inflows and outflows to present time; a positive NPV means the project exceeds the required rate of return.
- Benefit-cost ratio
- Benefit-cost ratio equals present value of benefits divided by present value of costs; a ratio greater than one indicates benefits exceed costs.
- Hierarchy of controls
- Hazard control effectiveness generally decreases from elimination and substitution through engineering controls and administrative controls to personal protective equipment.
- Lump-sum contract
- A lump-sum contract sets a fixed total price for a defined scope; the contractor bears cost-overrun risk unless authorized scope changes adjust the price.