All articles starting with P

Phase-change material microcapsules

Phase-change material microcapsules, also called microencapsulated phase change materials (MePCM), are micron-sized capsules that seal a phase change material, typically paraffin wax, in a thin polymer or inorganic shell.

Phase-change material slurry

A phase-change material slurry (PCS) is a pumpable fluid with phase-change particles dispersed in a carrying liquid, storing latent heat and holding more energy than water.

Phase-change memory

Phase-change memory (PCM), also called PCRAM, is a non-volatile solid-state memory storing data in the reversible phase change of a chalcogenide alloy such as Ge₂Sb₂Te₅.

Phase-change metamaterial

A phase-change metamaterial is an artificial electromagnetic structure whose resonant properties are switched by a phase-change material, most often the chalcogenide alloy GST, making it tunable and programmable.

Phase-change metasurfaces

Phase-change material reconfigurable metasurfaces are flat optical devices incorporating switchable materials such as Ge₂Sb₂Te₅, letting one fixed structure deliver beam steering, holography, and reconfigurable lenses.

Phase-change perfluorocarbon nanodroplets

Phase-change perfluorocarbon nanodroplets (PFCnDs) are submicrometer liquid perfluorocarbon particles that ultrasound or laser light converts into gas microbubbles, enabling on-demand contrast imaging and drug delivery.

Phase-change photonic switch

A phase-change photonic switch is an optical switching device that uses a chalcogenide phase-change material, typically GST, toggled between amorphous and crystalline states that hold without power.

Phase-change photonics

Phase-change photonics is the field of optics that uses phase-change materials, notably GST, switched reversibly by short pulses between amorphous and crystalline states, enabling nonvolatile photonic memory and reconfigurable devices with zero static power.

Phase-change solvent

A phase-change solvent is a liquid absorbent for CO2 capture that separates into CO2-rich and CO2-lean phases, so only the rich fraction is regenerated, lowering energy use.

Phase-contrast imaging

Phase-contrast imaging is a family of techniques that converts phase shifts of light, X-rays, or electrons into intensity contrast, revealing weakly absorbing structures; Frits Zernike invented the method in 1934.

Phase-contrast magnetic resonance imaging

Phase-contrast magnetic resonance imaging, also known as phase-contrast MRI, is an MRI technique that measures blood flow noninvasively by encoding fluid velocity into the signal phase.

Phase-contrast microscopy

Phase-contrast microscopy, also known as Zernike phase-contrast microscopy, is a light microscopy technique that makes transparent specimens such as living cells visible, invented by Dutch physicist Frits Zernike.

Phase-field fracture model

The phase-field fracture model is a computational mechanics method that simulates crack initiation and propagation in solids by representing cracks with a continuous scalar damage field.

Phase-field simulation of additive manufacturing solidification

Phase-field simulation of additive manufacturing solidification uses thermodynamics-based diffuse-interface models to predict how grains, cells, and dendrites form as metal solidifies in laser powder bed fusion and similar processes.

Phase-imaging ion-cyclotron-resonance mass spectrometry

Introduced in 2013 by Sergey Eliseev and Klaus Blaum, PI-ICR mass spectrometry is a Penning trap technique that measures atomic masses by projecting ion motion onto a sensitive detector.

Phase-locked loop

A phase-locked loop, or PLL, is a feedback control circuit that makes a voltage-controlled oscillator track the frequency and phase of a reference signal, first described in 1932.

Phase-out of incandescent light bulbs

The phase-out of incandescent light bulbs refers to government policies, starting with Australia in 2007 and followed by the EU, US, and Canada, that set efficiency standards.

Phase-sensitive amplification (spectroscopy)

Phase-sensitive amplification, also called lock-in amplification, is a signal-recovery technique that measures weak signals by detecting the component matching a known reference frequency, standard in spectroscopy for roughly a century.

Phase-sensitive optical time-domain reflectometry

Phase-sensitive optical time-domain reflectometry, or φ-OTDR, is a fiber-optic sensing technique that detects vibrations and acoustic waves, and is the principle behind most distributed acoustic sensing.

Phase-shift keying

Phase-shift keying (PSK), also known as biphase modulation, is a digital modulation method that encodes binary data by shifting a carrier's phase while amplitude stays constant.

Phase-shift mask

A phase-shift mask (PSM) is a photomask for optical lithography that shifts light's phase so adjacent waves cancel, printing features smaller than the exposure wavelength.

Phase-shifting holography

Phase-shifting holography is a digital holography technique, proposed by Ichirou Yamaguchi and Tong Zhang in 1997, that recovers the complex object wave from interferograms with known phase shifts.

Phase-shifting interferometry

Phase-shifting interferometry (PSI) is a technique for measuring an optical wavefront by recording several interferograms at known phase offsets and combining them into a phase map.

Phase-shifting transformer

A phase-shifting transformer (PST) is a specialized transformer that controls active power flow in three-phase transmission networks by regulating the voltage angle, letting operators direct power along chosen paths instead of physics-decided ones.

Phase-space formulation of quantum mechanics

The phase-space formulation of quantum mechanics represents quantum states and observables as functions on phase space, centered on the Wigner function introduced by Eugene Wigner in 1932.

Phase-space spiral

The phase-space spiral, also called the Gaia snail, is a spiral pattern in the velocities of stars near the Sun, discovered in Gaia data in 2018.

Phase-transfer catalysis

Phase-transfer catalysis (PTC) is a method in organic chemistry in which a quaternary ammonium or phosphonium salt carries ionic reactants between immiscible phases, applied in over 700 industrial processes.

Phase-type distribution

A phase-type distribution is the distribution of the time until absorption in a finite continuous-time Markov chain with transient phases, systematized by Marcel F. Neuts and applied in queueing, reliability, and insurance.

Phase–amplitude coupling

Phase–amplitude coupling (PAC) is a signal-analysis method quantifying how the amplitude of fast neural oscillations is modulated by the phase of slower ones, used to study cognition and diseases like Parkinson's.