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Four nuclear reactors hit a big milestone in the US

I was really looking forward to July 4, and not just because I love a poolside barbecue. This year the American holiday also marked a big symbolic deadline for US nuclear power. Last year the Trump administration set a goal to see three new microreactors achieve criticality, a technical milestone establishing that a reactor can…

2026-07-09 原文 →
AI 资讯

What Europe’s heat wave means for the power grid

It’s been hard to look away from headlines about the European heat wave this week. Temperatures are breaking records across the continent, and the weather is threatening lives, shutting down schools, and in one particularly ironic case, forcing the cancellation of a London Climate Action Week event about extreme heat. As the summer ramps up…

2026-06-25 原文 →
AI 资讯

Real-Time AI Feature Engineering with Spark Structured Streaming and Databricks Feature Store

Building point-in-time correct, production-grade feature pipelines — from raw Kafka events to online feature serving in milliseconds, using Spark Structured Streaming and the Databricks Feature Store. Table of Contents The Feature Engineering Problem Architecture Overview Feature Store Concepts: ERD Environment Setup Streaming Feature Pipeline Point-in-Time Correct Training Dataset Generation Writing Features to the Online Store Serving Features at Inference Time Feature Table Reference References The Feature Engineering Problem Feature engineering is where most ML projects silently fail in production. Not because the model is wrong — but because the features the model sees at training time are different from the features it sees at inference time . This is called training-serving skew , and it's the #1 silent killer of ML systems. Three specific failure modes cause it: Online/offline inconsistency — the batch pipeline that computes training features uses different logic than the real-time service that computes inference features Data leakage — training features accidentally include information from the future (e.g. joining on a label that was created after the event) Feature staleness — a model trained on 30-day rolling averages is served features that are 6 hours stale because the pipeline backfills are slow The Databricks Feature Store — now part of Unity Catalog as Feature Engineering in Unity Catalog — solves all three by: Storing feature computation logic alongside the data (no drift between training and serving) Enforcing point-in-time lookups during training dataset creation Providing a unified API for both batch offline reads and low-latency online reads Architecture Overview Feature Store Concepts: ERD Understanding the data model behind the Feature Store is essential for designing correct pipelines. Here's how the entities relate: The critical relationship: a Model Version is bound to a Training Set , which records exactly which feature tables and which p

2026-06-24 原文 →
AI 资讯

Apache Spark Query Optimization on Databricks: Catalyst, AQE, and Photon Engine

A deep dive into how Spark transforms your SQL into a physical execution plan — and how Databricks layers Adaptive Query Execution and the Photon vectorized engine on top to squeeze out maximum performance. Table of Contents Why Query Optimization Matters The Catalyst Optimizer Pipeline Stage 1: Parsing — From SQL to Unresolved Logical Plan Stage 2: Analysis — Binding to the Catalog Stage 3: Logical Optimization — Rule-Based Rewrites Stage 4: Physical Planning — Strategies and Cost Models Adaptive Query Execution (AQE) The Photon Engine Reading Explain Plans Tuning Reference Table References Why Query Optimization Matters A Spark query written by a human and a Spark query executed by the engine are often very different things. The gap between them — the optimization — is what separates a job that runs in 3 minutes from one that runs in 3 hours on identical hardware. Databricks compounds Spark's native Catalyst optimizer with two additional layers: Adaptive Query Execution (AQE) — re-optimizes the query at runtime using actual statistics collected mid-job Photon — a C++ vectorized execution engine that replaces the JVM-based Spark executor for eligible operators Understanding all three lets you write queries that cooperate with the engine rather than fight it. The Catalyst Optimizer Pipeline Catalyst is Spark's rule-based and cost-based query optimizer. Every query — whether written in SQL, DataFrame API, or Dataset API — passes through the same four-stage pipeline before a single byte of data is read. Stage 1: Parsing — From SQL to Unresolved Logical Plan # ── Catalyst Stage 1: Parsing ───────────────────────────────────────────────── # Spark uses ANTLR4 to parse SQL into an Abstract Syntax Tree (AST). # At this point column names are NOT validated — the plan is "unresolved". from pyspark.sql import SparkSession spark = SparkSession . builder . appName ( " catalyst-demo " ). getOrCreate () # Both of these produce identical internal representations df_api = ( spark .

2026-06-24 原文 →
AI 资讯

Geoengineering still faces major practical challenges

Solar geoengineering is often portrayed as a sort of emergency brake. Something along the lines of Pull in case of climate emergency to scatter light-reflecting particles to bounce sunlight out of the atmosphere and cool the planet. But it might be less like a simple brake and more like a complicated, entirely unsolved puzzle. Some…

2026-06-18 原文 →
开发者

Why China is betting on big nuclear reactors

It’s a tale of two nuclear industries. In China, large reactors are coming together at a stunning pace. The country has nearly doubled its nuclear fleet since 2016, reaching nearly 60 gigawatts of total power capacity. The new facilities are nearly all gigawatt-scale pressurized-water reactors. Meanwhile, the US has built just two reactors in that…

2026-06-11 原文 →
开发者

Climate tech companies are going public. What’s next?

This year, there’s been a wave of notable energy companies going public via IPO in the US. The solar and battery company Solv Energy went public in February, to the tune of $6 billion. X-energy, which is building small modular nuclear reactors, did the same in April, and its stocks surged on its first day…

2026-05-28 原文 →