OS
OpenStem
@openstem · Joined Jul 2026
7420 public items8 groups
Note~321 words · 2 min
Reynolds decomposition Split every field into a time-mean and a fluctuation about it. The mean is what you want to predict; the fluctuation is what makes it hard. Substitute into incompressible Navier-Stokes and time-average. Everything lin
Engineering · L5 · Turbulence: Reynolds Decomposition & Energy Cascade
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Engineering · L5 · Turbulence: Reynolds Decomposition & Energy CascadeNote~447 words · 2 min
No sensor gives you the state you actually care about. GPS is noisy, accelerometers drift, temperature probes lag. The Kalman filter fuses an imperfect model with imperfect measurements and beats either one alone. The model it assumes Predi
Engineering · L5 · The Kalman filter: optimal recursive state estimation
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Engineering · L5 · The Kalman filter: optimal recursive state estimationNote~478 words · 2 min
LQR gives you one fixed gain, computed offline from an unconstrained quadratic problem. Real actuators saturate and real states have safety limits, and LQR has no way to express either. MPC solves the optimisation online instead, with the c
Engineering · L5 · Model predictive control: optimizing a receding horizon under constraints
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Engineering · L5 · Model predictive control: optimizing a receding horizon under constraintsNote~475 words · 2 min
A manipulator is a chain of rigid links joined by joints. Two questions drive everything: given the joint angles, where is the tool? And given a desired motion, what torques do the motors need? Forward and inverse kinematics Denavit-Hartenb
Engineering · L5 · Robot kinematics and dynamics: from joint angles to end-effector motion
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Engineering · L5 · Robot kinematics and dynamics: from joint angles to end-effector motionPlot1 plot · 1 param
RC Charging: V(t) = 1 − e^(−t/τ)
@openstem
RC Charging: V(t) = 1 − e^(−t/τ)Plot1 plot · 1 param
RC Discharging: V(t) = e^(−t/τ)
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RC Discharging: V(t) = e^(−t/τ)Plot1 plot · 1 param
Step Response with Overshoot: 1 − e^(−x)·cos(b·x)
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Step Response with Overshoot: 1 − e^(−x)·cos(b·x)Plot1 plot · 1 param
Low-Pass Filter Magnitude: H(ω) = 1/√(1 + (ω/ω_c)²)
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Low-Pass Filter Magnitude: H(ω) = 1/√(1 + (ω/ω_c)²)Plot1 plot · 1 param
Power Dissipated vs. Current: P = R·I²
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Power Dissipated vs. Current: P = R·I²Plot1 plot · 1 param
Charge Stored vs. Voltage: Q = C·V
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Charge Stored vs. Voltage: Q = C·VPlot1 plot · 2 params
Instantaneous Voltage vs. Time: v(t) = Vpk·sin(ωt)
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Instantaneous Voltage vs. Time: v(t) = Vpk·sin(ωt)Plot1 plot · 2 params
Engineering · L5 · Damped Oscillatory Response
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Engineering · L5 · Damped Oscillatory ResponseFlowchart5 objects
Engineering · L1 · Light Bulbs Quiz · flowchart
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Engineering · L1 · Light Bulbs Quiz · flowchartFlowchart5 objects
Engineering · L1 · Sound Makers Quiz · flowchart
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Engineering · L1 · Sound Makers Quiz · flowchartFlowchart6 objects
Engineering · L1 · Building Simple Circuits · flowchart
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Engineering · L1 · Building Simple Circuits · flowchartFlowchart5 objects
Engineering · L1 · Air Takes Up Space · flowchart
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Engineering · L1 · Air Takes Up Space · flowchartFlowchart5 objects
Engineering · L2 · Matching Tools to Lever Classes · flowchart
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Engineering · L2 · Matching Tools to Lever Classes · flowchartFlowchart9 objects
Engineering · L2 · Batteries in Series vs Parallel · flowchart
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Engineering · L2 · Batteries in Series vs Parallel · flowchartFlowchart7 objects
Engineering · L2 · Pulleys & Mechanical Advantage — Worked Numbers · flowchart
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Engineering · L2 · Pulleys & Mechanical Advantage — Worked Numbers · flowchartFlowchart8 objects
Engineering · L2 · How Heat Travels · flowchart
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Engineering · L2 · How Heat Travels · flowchartFlowchart5 objects
Engineering · L2 · Hydraulics — Force Multiplication by the Numbers · flowchart
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Engineering · L2 · Hydraulics — Force Multiplication by the Numbers · flowchartFlowchart9 objects
Engineering · L2 · Standards & Codes · flowchart
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Engineering · L2 · Standards & Codes · flowchartFlowchart5 objects
Engineering · L2 · What Does a Capacitor Do? · flowchart
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Engineering · L2 · What Does a Capacitor Do? · flowchartFlowchart9 objects
Engineering · L2 · Engineering Evaporative Cooling · flowchart
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Engineering · L2 · Engineering Evaporative Cooling · flowchartFlowchart12 objects
Engineering · L2 · Requirements Gathering · flowchart
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Engineering · L2 · Requirements Gathering · flowchartFlowchart7 objects
Engineering · L2 · Choosing the Right Prototyping Method · flowchart
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Engineering · L2 · Choosing the Right Prototyping Method · flowchartFlowchart9 objects
Engineering · L3 · Specific Heat Capacity · flowchart
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Engineering · L3 · Specific Heat Capacity · flowchartFlowchart7 objects
Engineering · L3 · AC Circuits — Numeric Problems · flowchart
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Engineering · L3 · AC Circuits — Numeric Problems · flowchartFlowchart10 objects
Engineering · L3 · Viscosity in Engineering Practice · flowchart
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Engineering · L3 · Viscosity in Engineering Practice · flowchart