Multilayer plastic-film sorting
Can waste-sorting systems distinguish different layered plastic films fast enough to route them for recycling?
Engineering
Within Engineering · Search all subjects
Mobile terahertz beam management
Can narrow high-frequency wireless beams stay connected through movement and blockage without excessive tracking cost?
Membrane-distillation wetting control
Can seawater distillation membranes stay productive without letting salt water leak through their pores?
Nonthermal atmospheric water harvesting
Ultrasound can extract captured water efficiently. How can sorbent uptake and actuation stay coordinated as moisture loading and humidity change?
Microwave–optical quantum transduction
Can a practical interface transfer quantum information between microwave circuits and optical links with little loss or added noise?
Electrically pumped GeSn lasers
Germanium–tin lasers can work at room temperature when another laser powers them. Can an electric current do the job?
Elastocaloric work recovery
Squeezing and releasing a metal can move heat. Recovering the mechanical work must also reduce the electricity used by a complete cooler.
Solar thermochemical heat storage
Sunlight can dry a salt that releases heat when it takes up water again. Can durable pellets do this reliably inside an outdoor reactor?
Structural battery qualification
A structural battery stores energy while carrying load. How can one test sample reliably measure both jobs at once?
Iodine-compatible hollow cathodes
Iodine can fuel spacecraft thrusters. A hot electron source for higher-power systems must also survive the reactive iodine plasma.
Onboard hydrogen storage
Hydrogen tanks already power cars. Can a complete storage system carry enough usable fuel while meeting the weight, space, delivery and lifetime targets together?
Superhot geothermal well integrity
Very hot geothermal wells have been drilled. Can their casing, cement and seals keep working together for a power plant’s lifetime?
Orbital cryogenic refueling
Moving cold propellant between tanks on one spacecraft has been demonstrated. Can two separate spacecraft connect and transfer it reliably in orbit?
Thermophotovoltaic efficiency
A hot surface can feed light to a cell that makes electricity. Can measured conversion exceed 50% while unused light returns to the heat source?
Binary deletion channel capacity
What is the exact reliable information rate when bits disappear independently and the receiver cannot see where they were removed?
Worst-case trace reconstruction
Do polynomially many independently damaged copies always suffice to recover every unknown binary string exactly?
Long-read protein sequencing
Reading long, previously unknown proteins requires recognizing their chemical letters in order. Short-peptide identification is advancing; combining length, accuracy, speed and modified-letter recognition remains a demanding device target.
Room-temperature perovskite laser diodes
Perovskite crystals can lase continuously at room temperature when lit by another light source. A directly powered laser diode has now worked at 8 kelvin; bringing that operation to room temperature remains the target.
Human-scale organ cryopreservation
Rat kidneys have worked after cryogenic storage. Extending that success to a human-sized whole organ requires safe protective chemicals, ice-free cooling and uniform warming, followed by a demanding test of recovered function.
Superconducting aircraft motors
Superconducting coils can make powerful motors lighter, but they need deep cooling. NASA has tested major HEMM components; combining its full power, efficiency and low electromagnetic mass remains the motor target.
Atomic X-ray laser oscillators
An X-ray oscillator could repeatedly amplify light in excited atoms inside a crystal cavity. Atomic gain and fast copper-target delivery are demonstrated; assembling this into a coherent hard-X-ray oscillator remains a distinct device goal.
Shannon capacity of the seven-cycle
Seven symbols sit around a circle, and neighboring symbols can be confused. How many messages can long strings of these symbols carry with absolutely no decoding mistakes?
Binary symmetric channel reliability function
If each transmitted bit flips independently with a fixed probability, adding redundancy reduces mistakes. How quickly can the best possible error probability fall as the message block gets longer?
Li–Li network coding conjecture
Several senders share a network of two-way links. Can mixing their messages inside the network ever carry more independent traffic than forwarding and splitting the messages along paths?