Yaogan
Yaogan (Chinese: 遥感; pinyin: Yáogǎn) is a series of Earth observation satellites launched by the People's Republic of China since 2006, officially designated for civilian applications including land surveys, crop yield estimation, disaster monitoring, and scientific experiments.[1][2] However, orbital parameters, sensor capabilities, and deployment patterns indicate primary military utility for intelligence, surveillance, and reconnaissance (ISR), encompassing electro-optical imaging, synthetic-aperture radar (SAR) mapping, and electronic intelligence (ELINT) collection to support the People's Liberation Army (PLA).[3][4][5] The program has expanded rapidly, with over 45 satellites or groups deployed by 2025, often in trios for stereoscopic or formation-flying operations, launched via Long March rockets from sites including Jiuquan, Taiyuan, and Xichang.[6][7] Subseries such as Yaogan-30 focus on maritime surveillance via SAR, while others like Yaogan-41 enable geosynchronous optical monitoring, enhancing China's ability to track naval assets and regional threats in real time.[5][8] This buildup contributes to asymmetric space advantages, including persistent coverage over the Indo-Pacific, amid opaque state reporting that blends dual-use technologies to obscure strategic intent.[4][9] Notable advancements include high-resolution imaging potentially exceeding 0.8 meters and integration with ground systems for rapid data processing, positioning Yaogan as a cornerstone of PLA space-based warfare doctrines despite limited transparency on performance metrics.[3][10] International analyses highlight risks of escalation from such capabilities, including anti-satellite testing implications, though China's official narrative emphasizes peaceful utilization aligned with national development goals.[8][11]History and Development
Inception and Early Launches (2006–2010)
The Yaogan satellite series originated as China's inaugural dedicated effort to deploy a constellation of military reconnaissance platforms under the cover of civilian remote sensing missions. The inaugural launch occurred on April 27, 2006, when Yaogan-1 (also designated Jianbing-5 or JB-5) was placed into a sun-synchronous orbit of approximately 630 km altitude and 97.8° inclination using a Long March 4B rocket from the Taiyuan Satellite Launch Center. Equipped with synthetic aperture radar (SAR) for high-resolution, all-weather imaging, the satellite was officially tasked with conducting scientific experiments, surveying land resources, estimating crop yields, and aiding disaster relief efforts. However, assessments by U.S. defense analysts classify Yaogan-1 as China's first operational SAR reconnaissance satellite, primarily intended to gather military intelligence on terrain and mobile targets, addressing prior limitations in China's space-based imaging capabilities.[12][13] Early missions rapidly diversified payload types to build complementary intelligence, surveillance, and reconnaissance (ISR) functions, including electronic intelligence (ELINT) collection and electro-optical (EO) imaging. Yaogan-2 launched on November 6, 2006, via Long March 4C from Jiuquan, operating in a similar polar orbit and assessed as an ELINT platform for intercepting radar and communication signals from naval and ground targets. Yaogan-3 followed on May 27, 2007, again with Long March 4B from Taiyuan, featuring SAR for continued radar imaging refinement. By December 2008, Yaogan-5 introduced EO capabilities for daylight visible-light photography, launched on Long March 4B to a 630 km orbit, enabling higher-resolution target identification than SAR alone. These initial deployments demonstrated China's intent to integrate multiple sensor modalities, with launches averaging one to two per year, leveraging existing Long March variants for cost-effective access to space.[13][10] The period culminated in more complex configurations by 2009–2010, reflecting maturing orbital maneuvering and formation-flying technologies. Yaogan-6 (February 23, 2009) and Yaogan-4 (January 18, 2008) focused on ELINT in mid-inclination orbits for regional signals intelligence, while Yaogan-7 (July 5, 2009) added EO imaging. A milestone came with Yaogan-9, a triplet launched March 5, 2010, on Long March 4C from Taiyuan into a 1,100 km orbit for stereoscopic EO mapping, allowing three-dimensional terrain reconstruction for military planning. Yaogan-10 (August 11, 2010) returned to SAR with enhanced resolution. Overall, the 2006–2010 phase saw 10 satellites orbited, establishing a foundational network for persistent monitoring, though operational lifespans varied, with Yaogan-1 decaying in early 2010 after debris generation. U.S. Department of Defense reports highlight this buildup as part of China's broader military modernization, prioritizing space-based assets over purely terrestrial reconnaissance.[14][15][13]| Satellite | Launch Date | Vehicle/Site | Primary Capability | Orbit Notes |
|---|---|---|---|---|
| Yaogan-1 | April 27, 2006 | Long March 4B/Taiyuan | SAR imaging | 630 km, 97.8° SSO[13][12] |
| Yaogan-2 | November 6, 2006 | Long March 4C/Jiuquan | ELINT | Polar, ~630 km[13] |
| Yaogan-3 | May 27, 2007 | Long March 4B/Taiyuan | SAR imaging | SSO, ~630 km[13] |
| Yaogan-4 | January 18, 2008 | Long March 2D/Xichang | ELINT | Mid-inclination[16] |
| Yaogan-5 | December 15, 2008 | Long March 4B/Taiyuan | EO imaging | 630 km SSO[10] |
| Yaogan-6 | February 23, 2009 | Long March 4C/Jiuquan | ELINT | Polar[14] |
| Yaogan-7 | July 5, 2009 | Long March 2D/Xichang | EO imaging | SSO[10] |
| Yaogan-8 | December 15, 2009 | Long March 4C/Taiyuan | SAR imaging | SSO[13] |
| Yaogan-9 (triplet) | March 5, 2010 | Long March 4C/Taiyuan | EO stereo imaging | 1,100 km, 63°[15] |
| Yaogan-10 | August 11, 2010 | Long March 4C/Taiyuan | SAR imaging | ~610 km, 98°[13] |
Expansion and Technological Maturation (2011–2020)
From 2011 to 2020, the Yaogan program expanded markedly, with China executing over 25 launches that deployed dozens of satellites, transitioning from sporadic missions to routine deployments that bolstered the constellation's scale and diversity.[17] This period saw the introduction of multi-satellite groupings, particularly triplets for electronic intelligence (ELINT) and electromagnetic environment detection, such as Yaogan-16 launched on November 25, 2011, via Long March 4C from Jiuquan, mimicking U.S. NOSS configurations for ocean surveillance.[17] Subsequent ELINT missions, including Yaogan-17 in 2013 and Yaogan-20 in 2014, further populated inclined orbits to enhance geolocation of surface emitters.[17] Technological maturation manifested in refined sensor payloads and orbital architectures, enabling persistent monitoring. Synthetic aperture radar (SAR) satellites like Yaogan-13, launched November 29, 2011, from Taiyuan on a Long March 2C, provided all-weather imaging for resource assessment and military reconnaissance.[18][17] Electro-optical (EO) systems advanced in the Yaogan-30 series, initiated May 15, 2016, with launches from Jiuquan and Xichang using Long March 2D and 2C vehicles, focusing on naval target detection including U.S. aircraft carriers; by October 2019, at least 15 Yaogan-30 satellites achieved near-continuous global coverage.[18][17] These incorporated automated target recognition for ship identification, supporting anti-ship ballistic and cruise missile guidance.[18] Launch cadence intensified mid-decade, with six missions in 2014 alone utilizing varied vehicles like Long March 4B and 4C from Taiyuan and Jiuquan, deploying both single and triplet payloads in sun-synchronous orbits for electro-optical and SAR imaging.[17] By 2017–2020, Yaogan-30 extensions and Yaogan-31/32 groups emphasized electromagnetic surveys, with multiple triplet launches from Xichang, demonstrating improved reliability and integration for intelligence, surveillance, and reconnaissance (ISR) applications.[17][18] This maturation reduced revisit intervals and enhanced resolution, though exact sensor specifications remain classified, with assessments derived from orbital analysis and mission profiles.[18]Recent Deployments and Advancements (2021–Present)
Since 2021, China has accelerated deployments in the Yaogan series, launching multiple groups of satellites assessed as reconnaissance platforms for electro-optical, radar, and signals intelligence missions, despite official designations for civilian remote sensing applications such as land surveying and disaster monitoring. In November 2021, three Yaogan-35 satellites were deployed into low Earth orbit using a Long March 2D rocket from Xichang, forming a triplet configuration likely for electronic intelligence collection through coordinated orbital positioning. Subsequent Yaogan-36 missions in 2022 and 2023 introduced paired or triplet satellites with varied designs, including components built by DFH Satellite Co., orbiting at approximately 500 km altitude to enhance real-time surveillance capabilities.[19] In 2023, the Yaogan-39 group saw its fifth triplet launch in December via Long March 2D from Xichang, continuing the pattern of distributed aperture systems for improved electronic reconnaissance coverage.[20] By 2024, the program advanced with the Yaogan-43 series, deploying batches including nine satellites in August using a Long March 4B from Xichang, signaling expanded constellation density for persistent monitoring.[21] These developments reflect refinements in satellite clustering and sensor integration, enabling better resolution and revisit times over target areas.| Launch Date | Satellite Group | Number of Satellites | Launch Vehicle | Orbit/Notes |
|---|---|---|---|---|
| September 7, 2025 | Yaogan-40 (third trio) | 3 | Long March 4C | Polar orbit; remote sensing with enhanced polar coverage[6] |
| September 9, 2025 | Yaogan-45 | 1 | Long March 7A | Medium Earth orbit; strategic surveillance from higher altitude[4] |
Technical Specifications
Orbital Parameters and Configurations
The Yaogan satellite series primarily operates in low Earth orbit (LEO), with typical altitudes between 480 and 700 km for remote sensing missions, enabling high-resolution imaging and signals collection. Some electronic intelligence (ELINT) variants, such as early Yaogan-3 triads, deploy at approximately 1200 km altitude to facilitate wide-area surveillance. Orbital inclinations vary widely to support diverse mission profiles: sun-synchronous orbits (SSO) near 97–98° are common for electro-optical and synthetic-aperture radar (SAR) satellites to ensure consistent solar illumination, while lower inclinations like 35°, 43°, or 63.4° suit naval or regional monitoring. For instance, Yaogan-1, launched in 2006, entered a 607 × 621 km orbit at 98.7° inclination.[13] Satellite configurations often involve formations rather than isolated units, particularly for ELINT tasks requiring geolocation via time-difference-of-arrival methods. Triplets, such as those in the Yaogan-9/16/17 series, are launched into near-circular SSO at around 630 km and 98° inclination, with satellites phased approximately 120° apart in the same orbital plane for continuous coverage and triangulation accuracy. Similar setups appear in Yaogan-35 (2021), placed in a circular orbit of nearly 600 km at polar inclination. Single or paired deployments, like Yaogan-37 (2023) at 515 km and 43.2° inclination, support targeted reconnaissance.[15][23][24]| Satellite Example | Altitude (km) | Inclination (°) | Configuration | Launch Year |
|---|---|---|---|---|
| Yaogan-1 | 607 × 621 | 98.7 | Single | 2006 |
| Yaogan-11 | 640 | 98.4 | Single | 2010 |
| Yaogan-28 | 493–497 | 97.3 | Single | 2018 |
| Yaogan-3 series | ~1200 | 63.4 | Triad (120° phase) | 2008–2010 |
| Yaogan-9 series | ~630 | 98 | Triad | 2010–2018 |
Payload Technologies and Sensors
The Yaogan satellite series employs a variety of payload technologies tailored for military reconnaissance, including synthetic aperture radar (SAR) for all-weather imaging, electro-optical (EO) systems for high-resolution visible and infrared sensing, and electronic intelligence (ELINT) collectors for signals interception. These payloads are distributed across different orbital configurations and mission profiles, with SAR and EO often achieving resolutions sufficient for tactical intelligence, surveillance, and reconnaissance (ISR) applications. ELINT systems, typically deployed in multi-satellite formations, enable geolocation of emitters through time-difference-of-arrival techniques.[28][8][29] SAR sensors in Yaogan satellites, such as those on Yaogan-1, Yaogan-3, Yaogan-6, Yaogan-10, Yaogan-13, and Yaogan-18, utilize active microwave transmission to penetrate clouds and operate in darkness, with reported spatial resolutions better than 1.5 meters in models like Yaogan-29 operating at 615 km altitude. These systems likely operate in X-band or S-band frequencies to balance resolution and swath width, supporting applications from maritime surveillance to terrain mapping. Later variants, including Yaogan-42 launched in 2024, integrate SAR with other sensors for hybrid all-weather capability.[30][23][29] Electro-optical payloads, featured in satellites like Yaogan-2, Yaogan-4, Yaogan-7, and Yaogan-8 (military designation JB-6 series), deliver panchromatic imagery with resolutions of approximately 0.8 meters or finer from low Earth orbits around 600-700 km. The Yaogan-8 optical system, developed by the Changchun Institute of Optics, Fine Mechanics and Physics, supports multispectral imaging for enhanced target discrimination, while Yaogan-15 represents an evolution with improved revisit rates. These sensors are sunlight-dependent but provide detailed visible-spectrum data critical for identifying military assets and infrastructure.[3][31] ELINT payloads focus on passive collection of radar, communication, and telemetry signals, with Yaogan-9, Yaogan-16, and Yaogan-23 triplets forming baseline networks for trilateration-based localization over wide areas. Yaogan-29 incorporates ELINT alongside EO and SAR for comprehensive environmental probing, as do experimental groups like Yaogan-43. These systems feature directional antennas and wideband receivers to catalog electromagnetic signatures, aiding in electronic order-of-battle analysis.[30][32][33]Satellite Classes and Types
Synthetic-Aperture Radar (SAR) Capabilities
The Yaogan series incorporates synthetic-aperture radar (SAR) systems in several missions, classified under the Jianbing (JB) subclasses, to deliver all-weather and nighttime imaging for military reconnaissance. These active microwave sensors synthesize high-resolution images by leveraging the satellite's motion to simulate a large aperture, enabling detection of ground features through clouds, vegetation, and darkness. Early iterations focused on L-band operations for penetration depth, while later models emphasize finer detail for strategic intelligence, surveillance, and reconnaissance (ISR).[23] Yaogan-1, designated Jianbing-5 (JB-5) and launched on 27 April 2006 via Long March 4C from Taiyuan, marked China's first space-based SAR satellite, with a mass of 2,700 kg and an initial orbit of 601 × 621 km at 97.8° inclination, later adjusted to 628 × 629 km. Its L-band SAR provided resolutions of approximately 5 m (high-resolution mode) and 20 m (wide-swath mode), supporting basic terrain mapping and target detection. Follow-on JB-5 missions included Yaogan-3, launched 11 November 2007 into a 613 × 623 km orbit at 97.9° inclination, and Yaogan-10, launched 9 August 2010 into 607 × 621 km at 98.7° inclination, maintaining comparable L-band capabilities for persistent polar coverage.[13][23] The Jianbing-7 (JB-7) series, introduced from 2009 with four launches, advanced resolution to about 1.5 m through refined SAR processing and lower orbital altitudes of roughly 510 km at 97.4° inclination, enhancing utility for identifying vehicles, structures, and coastal assets. These second-generation systems, built by Shanghai Academy of Spaceflight Technology (SAST), prioritized weather-independent maritime and land surveillance. Subsequent developments, such as Yaogan-29 (launched November 2015 into 615 × 619 km at 97.8°), reportedly exceed 1.5 m resolution, possibly via improved JB-5 derivatives or hybrid modes. Newer efforts like Yaogan-33R (launched 2020 into 682 km at 98.7°), associated with Jianbing-X, indicate ongoing refinements in radar architecture for higher fidelity and multi-mode imaging.[23][34][35] These SAR assets operate in sun-synchronous orbits for repeatable passes, typically revisiting targets every few days, and integrate with ground stations for real-time data relay via L-band links. While official specifications remain classified, analyst assessments highlight progressive resolution gains from 5 m to sub-2 m, driven by antenna size increases and signal processing algorithms, bolstering People's Liberation Army applications in contested environments.[23][8]Electro-Optical (EO) Imaging Systems
The Yaogan series incorporates electro-optical (EO) imaging satellites designed to capture visible-light and near-infrared imagery for reconnaissance, with resolutions estimated at sub-meter to 2 meters based on orbital analysis and comparisons to known platforms. These systems, often classified under military designations like Jianbing-6 and Jianbing-10, feature three-axis stabilized buses with maneuvering capabilities for precise pointing and track adjustment during imaging passes. Early examples, such as Yaogan-2 (launched May 25, 2007, on a Long March 2D from Jiuquan), operated in a 630 km sun-synchronous orbit at 97.8° inclination, enabling panchromatic imagery with an estimated ground resolution of approximately 1.5 meters.[2][3] Subsequent EO satellites, including Yaogan-4 (launched December 1, 2008) and Yaogan-7, expanded this capability with similar orbital parameters and improved sensors inferred from launch configurations and mission durations, achieving resolutions potentially as fine as 0.8 meters or better for identifying vehicles and infrastructure.[3] The Jianbing-10 class, encompassing Yaogan-5 (launched December 15, 2008, via Long March 4B from Taiyuan), Yaogan-10 (launched December 26, 2010), Yaogan-12, and Yaogan-21, represents a maturation in optical reconnaissance, with payloads supporting both high-resolution panchromatic and multispectral imaging for target discrimination in military contexts.[10][36] These satellites maintain LEO altitudes around 500-700 km, prioritizing revisit rates over wide-area coverage to support tactical intelligence needs. Recent advancements include hybrid and persistent EO variants, such as Yaogan-34 (launched May 2021), described officially for land surveys but assessed for high-resolution optical remote sensing in inclined orbits up to 1,100 km.[7] Yaogan-41, deployed December 2023 via Long March 5 into geosynchronous orbit, introduces stationary EO surveillance with continuous monitoring potential over specific regions, marking a shift toward persistent wide-area observation.[5] Yaogan-45, launched September 2025 on a Long March 7A from Wenchang, further exemplifies ongoing EO deployments in sun-synchronous paths for enhanced resolution imaging.[37] Assessments of these systems' performance derive from open-source tracking data and launch telemetry, as Chinese state media emphasizes dual-use applications like disaster relief while Western analysts highlight primary ISR roles.[3][28]Electronic Intelligence (ELINT) Collection
The Yaogan satellite series incorporates electronic intelligence (ELINT) capabilities to detect and geolocate non-communicative radio frequency emissions, such as radar signals from naval vessels and ground-based systems, primarily for maritime surveillance. These missions enable triangulation through multi-satellite formations, providing coarse positional data that cues electro-optical or synthetic-aperture radar satellites for refined targeting, particularly in support of anti-access/area-denial strategies. Orbits for ELINT Yaogans often feature low Earth orbits with inclinations optimized for regional coverage, such as over the South China Sea or Western Pacific.[26][28] Yaogan-9, launched on March 5, 2010, from Jiuquan Satellite Launch Center aboard a Long March 4C rocket, represents China's inaugural ELINT triad, consisting of three satellites deployed in a 1,080–1,100 km circular orbit at 63.4° inclination, spaced approximately 120° apart in the same orbital plane. This configuration mirrors historical U.S. Naval Ocean Surveillance System (NOSS) designs, facilitating interferometric processing to locate radar emitters with sufficient accuracy for real-time tracking of surface ships. Assessments indicate its role in enhancing precision for anti-ship ballistic missiles by identifying carrier strike group emissions.[28][26] Subsequent ELINT missions evolved toward denser constellations for improved revisit rates and coverage. The Yaogan-30 series, beginning with Yaogan-30-01A/B/C launched in September 2017, operates in a lower 600 km orbit at 35° inclination, employing a six-satellite "spot" formation within the orbital plane to scan targeted areas like the Taiwan Strait and South China Sea with approximately 30-minute revisit intervals. These satellites detect RF signals over broad swaths, prioritizing emitter characterization over high-resolution imaging.[26][38] More recent examples include Yaogan-35 triplets, such as Yaogan-35-01 launched in November 2021, which Western analyses attribute to ELINT or signals intelligence functions due to their formation flying and sensor profiles, potentially integrating with hybrid payloads for emitter geolocation in contested maritime domains. Similarly, Yaogan-40 satellites, deployed in polar orbits starting around 2023–2024, extend global ELINT reach by monitoring high-latitude and oceanic radar activities. These developments reflect iterative advancements in sensor miniaturization and orbital mechanics, though exact payload specifications remain classified, with attributions derived from launch parameters, orbital behaviors, and parallels to known ELINT architectures.[39][6][40]Specialized and Hybrid Variants
Specialized variants of the Yaogan series deviate from standard low Earth orbit configurations to address niche operational requirements, such as persistent geosynchronous monitoring or medium Earth orbit deployments for extended coverage. For instance, Yaogan-41, launched on December 15, 2023, via a Long March 5 rocket from Wenchang, represents a geosynchronous optical reconnaissance satellite capable of near-continuous surveillance over specific regions, including potential maritime areas of interest like the South China Sea.[5] This variant's large payload, estimated at over 4,500 kg, enables higher-resolution imaging from GEO altitudes, contrasting with the typical sun-synchronous orbits of earlier Yaogan models, though Chinese state media described it generically for "remote sensing." Hybrid variants incorporate multi-function payloads or formation-flying architectures to fuse data types, enhancing geolocation accuracy for dynamic targets. The Yaogan-31 series, exemplified by the February 24, 2021, launch of a triplet (Yaogan-31 05A/B/C) on a Long March 4C from Jiuquan, operates as a naval ocean surveillance system analogous to the U.S. Naval Ocean Surveillance System (NOSS).[41] These satellites maintain a tight formation—typically one primary bus with two smaller sub-satellites—to triangulate radio frequency emissions from ships and submarines, combining electronic intelligence collection with potential synthetic aperture radar for surface vessel detection.[42] Western analyses, drawing from orbital parameters and historical precedents, assess this setup as optimized for anti-access/area denial (A2/AD) scenarios, enabling real-time tracking of adversary naval assets despite official claims of civilian environmental monitoring.[30] Emerging specialized designs include higher-altitude deployments like Yaogan-45, orbited on September 7, 2025, via Long March 7A to a medium Earth orbit of approximately 20,000 km, marking the second such Yaogan beyond LEO after Yaogan-41.[43] This configuration sacrifices some imaging resolution for wider revisit times and reduced vulnerability to low-orbit threats, supporting strategic surveillance over large theaters.[4] Hybrid elements may involve integrated electro-optical and signals intelligence sensors, as inferred from payload mass and mission profiles in similar series, though exact capabilities remain classified and unconfirmed beyond orbital telemetry.[26] These variants underscore the People's Liberation Army's push toward resilient, multi-domain ISR architectures, with empirical evidence from launch cadences and international tracking data indicating prioritization of contested maritime domains over purely terrestrial focus.[8]Launch Operations
Primary Launch Vehicles and Sites
The Yaogan satellite series primarily utilizes variants of the Long March (Chang Zheng) expendable launch vehicles, produced by the China Academy of Launch Vehicle Technology, to deploy payloads into low Earth orbit configurations suitable for reconnaissance missions. Key vehicles include the Long March 2C (CZ-2C), which supports payloads up to approximately 2,200 kg to sun-synchronous orbit and has been used for multiple triplet deployments; the Long March 2D (CZ-2D), an enhanced version capable of similar orbits with improved reliability; the Long March 4B (CZ-4B), employed for heavier payloads or formation flying satellites; and the Long March 4C (CZ-4C), optimized for polar sun-synchronous orbits with a capacity of about 4,000 kg to 700 km altitude.[44][13][3] These selections align with mission-specific requirements, such as orbital inclination and satellite mass, with over 50 Yaogan launches documented using these rockets since the series inception in 2006.[17] Launches are conducted from China's three major satellite launch centers: Jiuquan Satellite Launch Center (JSLC) in Gansu Province, which handles the majority of Yaogan missions into sun-synchronous or low-inclination orbits due to its northern location and eastward trajectory over the Yellow Sea; Taiyuan Satellite Launch Center (TSLC) in Shanxi Province, preferred for polar sun-synchronous orbits essential for global coverage in synthetic aperture radar (SAR) and electronic intelligence (ELINT) variants, leveraging its higher latitude for direct polar access; and Xichang Satellite Launch Center (XSLC) in Sichuan Province, used for missions requiring southeastern trajectories, including some electro-optical imaging satellites.[17][6][45] Jiuquan has hosted launches like Yaogan-30 Group-05 on a CZ-2C on July 25, 2019, while Taiyuan supported Yaogan-40 (03) via Long March 6A on September 7, 2025, and Xichang facilitated Yaogan-35 on a CZ-2D on November 6, 2021.[44][6][45]| Launch Vehicle | Primary Site Usage | Example Yaogan Mission |
|---|---|---|
| Long March 2C | Jiuquan (JSLC) | Yaogan-30 Group-05 (2019)[44] |
| Long March 2D | Xichang (XSLC), Jiuquan | Yaogan-35 (2021)[45] |
| Long March 4C | Taiyuan (TSLC), Jiuquan | Yaogan-9 series[15] |
| Long March 4B | Taiyuan (TSLC) | Yaogan-26 (2014)[3] |