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Precoded OFDM
Precoded OFDM is a transmission scheme in which data symbols are multiplied by a precoding matrix before OFDM modulation, lowering peak-to-average power ratio and adding multipath protection.
Precoding
Precoding is a transmitter-side signal processing technique that shapes per-antenna signals of a multi-antenna transmitter using channel state information, directing energy toward receivers and suppressing interference; it is used in LTE and 5G.
Precoding codebook feedback
Precoding codebook feedback is a limited-feedback MIMO wireless technique in which the receiver selects a precoding matrix from a shared codebook and reports only its index, enabling closed-loop transmission.
Precombustion chamber
A precombustion chamber is a small auxiliary combustion chamber, connected to an engine cylinder by a narrow passage, in which fuel is first partly burned.
Precursor cathode active material
Precursor cathode active material (pCAM) is a mixed nickel-cobalt-manganese hydroxide intermediate from which lithium-ion battery cathode powder is made by lithiation and calcination; it is produced almost entirely by co-precipitation.
Predicate pushdown
Predicate pushdown, or filter pushdown, is a query optimization passing WHERE-clause predicates to the data source, Spark connectors, Trino connectors, or Parquet row-group statistics, so non-matching rows, files, or blocks are never read.
Predicted local distance difference test
The predicted local distance difference test (pLDDT) is a per-residue confidence score produced by AlphaFold, reported on a scale from 0 to 100, with higher values indicating higher accuracy.
Prediction Algorithms
A prediction algorithm is a computational procedure that uses historical or real-time data to estimate future or unknown values, spanning statistical time-series models and deep learning.
Predictive analytics
Predictive analytics is the practice of using historical data with statistical and machine-learning models to predict outcomes like demand forecasts, credit default probabilities, and customer churn scores.
Predictive current control
Predictive current control (PCC) is a power electronics control method that predicts the load current for each candidate switching state and applies the one minimizing the predicted error.
Predictive display
A predictive display is a teleoperation visual aid that shows the operator a real-time estimate of a remote robot's future state, compensating for communication time delay.
Predistortion
Predistortion is a linearization technique that deliberately distorts a transmit signal before a power amplifier, canceling the amplifier's nonlinearity so transmitters can run near saturation efficiently.
Preem
Preem is a Swedish fuel company that refines and sells gasoline, diesel, and renewable fuels at its Lysekil and Gothenburg refineries. Founded in 1996, it is Sweden's largest fuel producer.
PREEMPT_RT
PREEMPT_RT, the real-time preemption patch set, makes the Linux kernel almost fully preemptible through sleeping locks and threaded interrupts, reaching mainline with Linux 6.12 in 2024.
Preemption (computing)
Preemption in computing is the forced suspension of a running task by the operating system, the mechanism behind preemptive multitasking, used by Linux, Windows, and macOS.
Prefabricated vertical drain
A prefabricated vertical drain (PVD) is a manufactured geosynthetic drain inserted into soft ground to shorten drainage paths and consolidation time, usually with a surcharge or vacuum preloading.
Prefabricated vertical drains
A prefabricated vertical drain (PVD), also called a wick drain or band drain, is a geosynthetic strip driven through soft clay to shorten drainage paths and accelerate consolidation under embankment preloads.
Prefabrication
Prefabrication, also called prefabricated construction, is a construction method in which components are manufactured under controlled conditions, then transported and assembled on site, as in immersed tube tunnels.
PRefChem
PRefChem (Pengerang Refining and Petrochemical) is the name for two joint ventures of PETRONAS and Saudi Aramco operating a 300,000-barrel-per-day refinery and petrochemical complex in Pengerang, Johor, Malaysia, started up in 2019.
Preference learning
Preference learning is the branch of machine learning that models preferences from comparative data like ratings and rankings, spanning rank aggregation, recommender systems, and RLHF for aligning language models.
Preference optimization
Preference optimization is a family of fine-tuning methods that aligns language models with human preferences by training on paired judgments of candidate outputs rather than reward models.
Preferred Networks
Preferred Networks, also known as PFN, is a Tokyo deep-learning company founded in 2014 by Toru Nishikawa and Daisuke Okanohara, known for the PLaMo AI models and MN-Core chips.
Prefetching (computing)
Prefetching is a computer architecture technique in which data or instructions are fetched into a cache before the processor requests them, hiding memory latency. It is done by hardware or software.
Prefill-decode disaggregation
Prefill-decode disaggregation is a serving architecture that runs prompt processing and token generation for large language models on separate hardware, transferring the KV cache between them.
Prefix sum
A prefix sum, also called a scan or cumulative sum, is an operation on a list of numbers that produces a running total at each position.
Prefix tuning
Prefix tuning is a parameter-efficient fine-tuning method for pretrained transformers, introduced by Xiang Lisa Li and Percy Liang in 2021, that trains prefix vectors while the model stays frozen.
Prefix/context caching
Prefix/context caching is an inference technique that stores and reuses key-value states for shared prompt prefixes, cutting prefill cost and latency; adopted by major providers in 2024–2025, it discounts cache-hit tokens by 50 to 90%.
Prehensile grasping
Prehensile grasping is robotic manipulation in which a gripper holds an object by closing fingers or jaws around it, rather than pushing, rolling, or throwing it.
Preliminary design review
A preliminary design review (PDR) is a formal technical assessment held near the end of preliminary design that confirms a system meets requirements before detailed design begins.
Prelude FLNG
Prelude FLNG, also known as Shell Prelude, is a Shell-operated floating liquefied natural gas facility off Western Australia, the largest floating offshore facility ever built.