Besides the RDD-oriented functional style of programming, Spark provides two restricted forms of shared variables: broadcast variables reference read-only data that needs to be available on all nodes, while accumulators can be used to program reductions in an imperative style.
The light emitted by a spark does not come from the current of electrons itself, but from the material medium fluorescing in response to collisions from the electrons. When electrons collide with molecules of air in the gap, they excite their orbital electrons to higher energy levels. When these excited electrons fall back to their original energy levels, they emit energy as light. It is impossible for a visible spark to form in a vacuum. Without intervening matter capable of electromagnetic transitions, the spark will be invisible (see vacuum arc).
In October 2011, General Motors announced the production of the Chevrolet Spark EV, an all-electric version of the third-generation Chevrolet Spark, with availability limited to select markets. The production version was unveiled at the November 2012 Los Angeles Auto Show.
Spark Core is the foundation of the overall project. It provides distributed task dispatching, scheduling, and basic I/O functionalities, exposed through an application programming interface (for Java, Python, Scala, and R) centered on the RDD abstraction (the Java API is available for other JVM languages, but is also usable for some other non-JVM languages that can connect to the JVM, such as Julia ). This interface mirrors a functional/higher-order model of programming: a "driver" program invokes parallel operations such as map, filter or reduce on an RDD by passing a function to Spark, which then schedules the function's execution in parallel on the cluster. These operations, and additional ones such as joins, take RDDs as input and produce new RDDs. RDDs are immutable and their operations are lazy; fault-tolerance is achieved by keeping track of the "lineage" of each RDD (the sequence of operations that produced it) so that it can be reconstructed in the case of data loss. RDDs can contain any type of Python, Java, or Scala objects.
Spark SQL is a component on top of Spark Core that introduced a data abstraction called DataFrames, which provides support for structured and semi-structured data. Spark SQL provides a domain-specific language (DSL) to manipulate DataFrames in Scala, Java, or Python. It also provides SQL language support, with command-line interfaces and ODBC/JDBC server. Although DataFrames lack the compile-time type-checking afforded by RDDs, as of Spark 2.0, the strongly typed DataSet is fully supported by Spark SQL as well.
Within the framework of GM's vehicle electrification strategy, the Spark EV was the first all-electric passenger car marketed by General Motors in the U.S. since the EV1 was discontinued in 1999. The Spark EV was released in the U.S. in selected markets in California and Oregon in June 2013. The electric car has gone on sale in Maryland in the second quarter of 2015, the first East Coast state where the Spark EV is available. , U.S. sales totaled 1,684 units. The Spark EV was discontinued in December 2016, when Chevrolet began selling the Bolt, which had a much longer range.
In October 2012, GM Korea announced it would start making and selling the Spark EV in Korea in 2013. Retail sales began in South Korea in October 2013. GM also announced plans to sell the Spark EV in limited quantities in Canada and select European markets. It is available in Canada for fleet sales.
In Spark 2.x, a separate technology based on Datasets, called Structured Streaming, that has a higher-level interface is also provided to support streaming.
Spark Streaming uses Spark Core's fast scheduling capability to perform streaming analytics. It ingests data in mini-batches and performs RDD transformations on those mini-batches of data. This design enables the same set of application code written for batch analytics to be used in streaming analytics, thus facilitating easy implementation of lambda architecture. However, this convenience comes with the penalty of latency equal to the mini-batch duration. Other streaming data engines that process event by event rather than in mini-batches include Storm and the streaming component of Flink. Spark Streaming has support built-in to consume from Kafka, Flume, Twitter, ZeroMQ, Kinesis, and TCP/IP sockets.
Spark can be deployed in a traditional on-premises data center as well as in the cloud.
The 2014 production version featured a 130 hp motor, providing 400 lbft of torque. The Spark EV can be fast-charged to 80% of capacity in 20 minutes using an optional CCS/SAE Combo Type 1 connector, and charging time increases to about seven hours using a dedicated 240-volt charging station or about 17 hours using a standard household 120-volt outlet.
Spark offers asymmetric digital subscriber line (ADSL), very-high-bit-rate digital subscriber line (VDSL) and fibre to the premises (FTTP) fixed-line broadband. FTTP customers may choose either 30/10 Mbit/s, 100/20 Mbit/s, 200/20 Mbit/s, 200/200 Mbit/s, or in selected areas, 1000/500 Mbit/s maximum speed (down/up); ADSL and VDSL customers' download speeds are only limited to what their line and equipment can handle, while upload speeds are limited to 1 Mbit/s and 10 Mbit/s respectively. All three offer both data-capped and unlimited plans. Data-capped customers may choose either to pay extra per GB (or part thereof) over their data cap, or have their speed throttled back to 128 kbit/s at no charge once they exceed the cap. Unlimited plans have no data caps.
"Indexing" of plugs upon installation involves installing the spark plug so that the open area of its gap, not shrouded by the ground electrode, faces the center of the combustion chamber rather than one of its walls. The theory holds that this will maximize the exposure of the fuel-air mixture to the spark, also ensuring that every combustion chamber is even in layout and therefore resulting in better ignition. Indexing is accomplished by marking the location of the gap on the outside of the plug, installing it, and noting the direction in which the mark faces. Then the plug is removed and washers are added to change the orientation of the tightened plug. This must be done individually for each plug, as the orientation of the gap with respect to the threads of the shell is random. Some plugs are made with a non-random orientation of the gap and are usually marked as such by a suffix to the model number; typically these are specified by manufacturers of very small engines where the spark plug tip and electrodes form a significantly large part of the shape of the combustion chamber. The Honda Insight has indexed spark plugs from factory, with four different part numbers available corresponding to the different degrees of indexing to achieve most efficient combustion and maximal fuel efficiency.
Spark Ultra Mobile is New Zealand's second-largest mobile operator by market-share, behind Vodafone. Telecom's mobile network was branded as "XT", and operates at 850 MHz nationwide (with some 2100 MHz overlay in urban areas), and delivers 3G data connectivity wherever there is coverage.
A spark plug is composed of a shell, insulator and the central conductor. It passes through the wall of the combustion chamber and therefore must also seal the combustion chamber against high pressures and temperatures without deteriorating over long periods of time and extended use.
An idling engine will have a different impact on the spark plugs than one running at full throttle. Spark plug readings are only valid for the most recent engine operating conditions and running the engine under different conditions may erase or obscure characteristic marks previously left on the spark plugs. Thus, the most valuable information is gathered by running the engine at high speed and full load, immediately cutting the ignition off and stopping without idling or low speed operation and removing the plugs for reading.
Spark plugs are specified by size, either thread or nut (often referred to as Euro), sealing type (taper or crush washer), and spark gap. Common thread (nut) sizes in Europe are 10 mm (16 mm), 14 mm (21 mm; sometimes, 16 mm), and 18 mm (24 mm, sometimes, 21 mm). In the United States, common thread (nut) sizes are 10mm (16mm), 12mm (14mm, 16mm or 17.5mm), 14mm (16mm, 20.63mm) and 18mm (20.63mm).
SPARK is an acronym for the Schools core values: Service, Persistence, Achievement, Responsibility and Kindness. The name of the network also took inspiration from the quotation often misattributed to William B. Yeats quote; "Education is not the filling of a pail, but the lighting of a fire". While this quotation is often attributed to the Irish poet W.B. Yeats there is no evidence that he ever wrote or said those words.
The gap adjustment can be crucial to proper engine operation. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, but the plug will almost always fire on each cycle. A gap that is too wide might prevent a spark from firing at all or may misfire at high speeds, but will usually have a spark that is strong for a clean burn. A spark which intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and fuel efficiency.
One Spark's third event was held April 7-12, 2015 in downtown Jacksonville. It holds the record for highest attendance for a One Spark event at over 320,000. One Spark claims it was the world's largest crowdfunding event.