1,786 research outputs found
Impatiens kurichiarmalayana Saravanan & Kaliamoorthy 2022, sp. nov.
No full textImpatiens kurichiarmalayana Saravanan & Kaliamoorthy, sp. nov. (Figure 2) Impatiens kurichiarmalayana is similar to I. mankulamensis K. M. P. Kumar, R. Jagad. & Nagaraj (2017: 281) and I. panduranganii K. M. P. Kumar, R. Jagad. & G. Prasad (2017: 285) in having common characters viz., rosulate leaves, umbellate cyme inflorescence, unequally bilobed wing petals and shorter basal lobes. But differs from I. mankulamensis by having ovate-lanceolate leaves (vs elliptic, lanceolate-oblanceolate in I. mankulamensis), lateral sepals white with dark purple tinges at the apex (vs white with brown tinges at tip in I. mankulamensis), dorsal petal white (vs pale purple in I. mankulamensis), presence of dorsal auricle (vs absence in I. mankulamensis) and absence of spur (vs present in I. mankulamensis); Impatiens kurichiarmalayana also differs from I. panduranganii by having white flowers with dark purple spot at the base of the wing petals (vs white with light purple dots in I. panduranganii), dorsal petal keeled at apex (vs not keeled in I. panduranganii), distal lobe spreading and broadly obovate (vs not spreading and shoe shaped in I. panduranganii), lower sepal white with yellow mark at middle and dark brown streaks horizontally (vs white with yellow tinges in I. panduranganii) (Table 2). Type:— INDIA. Kerala: Wayanad District, Kurichiarmala Reserve Forest, 11º36’2”N, 75º57’57”E, 1200–1320 m, 11 December 2019, Saravanan & Kaliamoorthy 136030 (holotype & isotype MH!). Epiphytic tuberous herbs. Stem simple, erect, to 19.5 cm tall, succulent, yellowish green in lower portion, distally reddish purple, leaves bearing portion greenish, glabrous. Tubers ca 0.9 × 0.5 cm, oblong, pale brownish white. Leaves crowned at top; lamina 0.9–2.6 × 0.4–1.2 cm, elliptic-ovate to lanceolate, obtuse or apiculate to retuse at apex, attenuate at base, apiculate-crenate at margins, light green and hairy only on nerves adaxially, purplish green and glabrous abaxially; lateral nerves 3–4 pairs; petioles 1.1–2.5 cm long, purplish, glabrous. Inflorescence a subumbellate racemes; peduncle 7.5–9.7 cm long, 3–4-flowered, dark purplish red, glabrous. Flowers 1.7–1.9 cm across, white with dark purple spots at base of distal and basal lobes, glabrous; pedicels ca 0.9 cm long, purplish green, glabrous; bracts ca 0.4 × 0.1 cm, ovate to oblong-lanceolate, acuminate and mucronate at apex, concave, pale greenish with purple lines, glabrous; lateral sepals ca 0.5 × 0.2 cm, elliptic-oblong, acuminate and mucronate at apex, slightly concave, mid nerve pale purplish with dark purple apex; dorsal petal ca 0.6 × 0.3 cm, broadly ovate-orbicular, obtuse, concave, margins wavy, dorsally keeled; keel mucronate at apex; mucro ca 0.1 cm long; wing petals unequally 2-lobed, 1.5–1.7 × 0.5–0.7 cm; claw 0.3–0.4 cm long, glabrous; basal lobe much smaller than distal lobe, ca 0.5 × 0.2 cm, triangular-ovate in outline, acute-acuminate at apex; distal lobe ca 1.2 × 0.5 cm, broadly obovate, obtuse to truncate at apex, notched towards inner side much below the apex; dorsal auricle ca 0.1 cm long, triangular, obtuse at apex, yellowish; lower sepal saccate, ca 0.6 × 0.4 cm, ca 0.2–0.3 cm deep, ovate, obtuse and mucronate at apex, white with yellowish mark at middle, and dark purple streaks horizontally; spur absent; stamens ca 0.4 × 0.2 cm, slightly curved; filaments 5, ca 0.3 × 0.1 cm, creamy white; anthers ca 0.1 × 0.1 cm; ovary ca 0.2 × 0.1 cm, glabrous. Capsules 0.7–1.0 × 0.2–0.3 cm, ellipsoid-clavate, greenish, glabrous; seeds minute, 0.1 cm long, sub-globose, pale yellow, with short white hairs scattered all over the surface. Phenology:—Flowering & fruiting: June–September. Ecology:—Growing on moss covered wet tree trunks in evergreen forests, in association with Bulbophyllum fischeri Seidenf. (1974: 202), Eria albiflora Rolfe (1893: 170) and Oberonia brunoniana Wight (1851: 1622), at an elevation of 1319 m. Conservation Status:— Impatiens kurichiarmalayana is only known from the type locality with about 10–15 mature individuals. The population is well conserved within the boundaries of protected forest areas. However, considering the lesser number of individuals in a single population size distributed in an area of hardly 0.3 km, the species described here is assessed as Critically Endangered (CE) by applying the criterion d (IUCN 2019). Etymology:—The specific epithet is named after the type locality, Kurichiarmala evergreen forests, Wayanad district, Kerala, India. Notes:— Impatiens kurichiarmalayana shows also similarities with I. travancorica Bedd. (1874: 29), in having a rosulate leaves, sub-umbellate raceme inflorescence, white flowers with dark purple patches near the base of the wing petals, sub-globose seeds with short hairs all over, but differs by its habit (Epiphytic tuberous herbs in I. kurichiarmalayana vs annual herbs in I. travancorica), size and shape of the lateral sepals (elliptic-oblong in I. kurichiarmalayana vs obliquely ovate in I. travancorica), dorsal petal (broadly ovate-orbicular in I. kurichiarmalayana vs cucullate in I. travancorica), dorsal auricle (present in I. kurichiarmalayana vs absent in I. travancorica) and spur (absent in I. kurichiarmalayana vs present in I. travancorica).Published as part of Saravanan, Thokuluva Santharam & Kaliamoorthy, Seventhilingam, 2022, Two new epiphytic species of Impatiens L. (Balsaminaceae) from the southern Western Ghats, India, pp. 107-114 in Phytotaxa 552 (1) on pages 110-111, DOI: 10.11646/phytotaxa.552.1.10, http://zenodo.org/record/667313
Impatiens keralensis Saravanan & Kaliamoorthy 2022, sp. nov.
No full textImpatiens keralensis Saravanan & Kaliamoorthy, sp. nov. (Figure 1) Impatiens keralensis is closely allied to I. modesta Wight (1837: 13) and I. mohana Ratheesh, Sujana & Anil Kumar (2012: 282) in having common characters of a scapigerous tuberous habit, radical leaves, ovate-cordate lamina, unequally trilobed wing petals, and a blunt spur. But differs from I. modesta by having multicellular trichomes on adaxial leaf surfaces (vs unicellular hairs on adaxial leaf surfaces in I. modesta), short petioles (vs long petioles in I. modesta), short scapes (vs long scapes in I. modesta) and 3–6-flowered inflorescence (vs many flowered inflorescence in I. modesta), white flowers (vs pinkish/whitish in I. modesta), pedicels longer than flowers, lateral united petals white with yellowish purple papillose at the base of mid-lobe (vs yellowish with a tuft of purple hairs in I. modesta), and basal lobes emarginate at apex (vs obtuse in I. modesta); Impatiens keralensis also differ from I. mohana by having multicellular trichomes on adaxial on leaf surface (vs multicellular trichomes on both adaxial and abaxial leaf surfaces in I. mohana), spinose at margins (vs absence of spinose in I. mohana), glabrous petiole (vs trichomatous in I. mohana), and white flowers (vs deep pinkish in I. mohana) (Table 1). Type:— INDIA. Kerala: Wayanad District, Kurichiarmala Reserve Forest, 11º36’1”N, 75º57’59”E, 1100–1320 m, 11 December 2019, Saravanan & Kaliamoorthy 136020 (holotype MH!). Scapigerous, tuberous acaulescent, epiphytic herbs, 5–10 cm tall. Tubers sub-globose, 0.8 × 0.7 cm, brownish white. Stem-less. Leaves radical, 2-3 per tuber, 1.5–4.2 × 1.0– 3.5 cm, broadly ovate to cordate in outline, deeply cordate to auriculate-cordate at base, crenate-serrate and spinose at margins, obtuse at apex, adaxially covered with multicellular white trichomes, greenish; abaxially glabrous, pale purplish green, with 3-4 pairs of lateral nerves; petioles 1.9–3.3 cm long, pale reddish with purple streaks, glabrous. Inflorescence racemose; peduncle longer than the leaves, ca 6.5 cm long, 3–6-flowered, glabrous, terete, pale reddish with purple streaks; Flowers 0.6–0.8 cm across, white; bracts 0.3 × 0.1 cm, slightly falcate, obtuse at apex, glabrous, green with purple streaks, thick and fleshy; pedicel longer than the flowers, ca 1.3 cm long, filiform, pale reddish with purple streaks, glabrous; lateral sepals 0.2 × 0.1 cm, obliquely oblong, obtuse at apex, glabrous; dorsal petal ca 0.2 × 0.2 cm, concave, orbicular to reniform, obtuse at apex, forming a hood above the androecium, dorsally humped at base, glabrous; wing petals free, unequally 3-lobed, 1.4–1.5 × 0.6–0.8 cm, white with a tuft of deep yellowish purple papillose at the base of mid-lobe; basal lobe ca 0.7 × 0.2 cm, oblong, broadest at the middle, slightly up-curved, emarginate at apex; mid-lobe ca 0.5 × 0.2 cm, oblong, obtuse to truncate at apex; distal lobe ca 0.7 × 0.2 cm, oblong, obtuse to truncate at apex; dorsal auricle absent; lower sepal ca 0.3 × 0.2 cm, ovate, obtuse at apex, concave, white, 0.1 cm deep, glabrous; spur ca 0.3 × 0.1 cm, straight, white, glabrous; stamens ca 0.2 cm long, curved; filaments ca 5, 1.3 mm long, narrow and free at base, fused and broad at apex, light pink to white; anthers 5, ca 1.0 × 0.4 mm, white, cohering above the pistil; pistil ca 1.2 × 0.3 mm; ovary broadly obclavate to ellipsoid, glabrous. Capsules 0.5–0.8 cm long, broadly ellipsoid, greenish, glabrous; seeds minute, comose with tuft of hairs at both ends. Phenology:—Flowering & fruiting: August–November. Ecology:—Growing on moss covered wet tree trunks in evergreen forests, along with Impatiens veerapazhasii Ratheesh, Sujanapal & Meera (2011: 154), Oberonia bicornis Lindl. (1830: 16) and Oberonia swaminathanii Ratheesh, Manudev & Sujanapal (2010: 713), at an elevation of 1310 m. Conservation Status:— Impatiens keralensis is only known from the type locality with about 10–12 mature individuals. The population is well conserved within the boundaries of protected forest areas. However, considering the lesser number of individuals in a single population size distributed in an area of hardly 0.3 km, the species described here is assessed as Critically Endangered (CE) by applying the criterion d (IUCN 2019). Etymology:—The species is named after the Kerala state, India, where the type locality is present. Notes:— Impatiens keralensis is also allied to I. dendricola C. E. C. Fisch. (1935:157), in having a tuberous scapigerous epiphytic habit, radical leaves, flowers in racemose scapes, white flowers and presence of spur, but differs in the size and shape of the bract (slightly falcate in Impatiens keralensis vs ovate in I. dendricola), lateral sepals (obliquely oblong in Impatiens keralensis vs asymmetrically ovate in I. dendricola), dorsal petal (obtuse at apex in Impatiens keralensis vs retuse at apex in I. dendricola), wing petals (papillose at the base of mid-lobe in Impatiens keralensis vs hairs at the base in I. dendricola), spur (straight in Impatiens keralensis vs clavate in I. dendricola), and dorsal auricle (absent in Impatiens keralensis vs present in I. dendricola).Published as part of Saravanan, Thokuluva Santharam & Kaliamoorthy, Seventhilingam, 2022, Two new epiphytic species of Impatiens L. (Balsaminaceae) from the southern Western Ghats, India, pp. 107-114 in Phytotaxa 552 (1) on pages 107-110, DOI: 10.11646/phytotaxa.552.1.10, http://zenodo.org/record/667313
Analysis of CryptoNote Transaction Graphs Using the Dulmage-Mendelsohn Decomposition
No full textCryptoNote blockchains like Monero represent the largest public deployments of linkable ring signatures. Beginning with the work of Kumar et al. (ESORICS 2017) and Möser et al. (PoPETs 2018), several techniques have been proposed to trace CryptoNote transactions, i.e. identify the actual signing key, by using the transaction history. Yu et al. (FC 2019) introduced the closed set attack for undeniable traceability and proved that it is optimal by showing that it has the same performance as the brute-force attack. However, they could only implement an approximation of the closed set attack due to its exponential time complexity. In this paper, we show that the Dulmage-Mendelsohn (DM) decomposition of bipartite graphs gives a polynomial-time implementation of the closed set attack. Our contribution includes open source implementations of the DM decomposition and the clustering algorithm (the approximation to the closed set attack proposed by Yu et al). Using these implementations, we evaluate the empirical performance of these methods on the Monero dataset in two ways - firstly using data only from the main Monero chain and secondly using data from four hard forks of Monero in addition to the main Monero chain. We have released the scripts used to perform the empirical analysis along with step-by-step instructions
Policies are never implemented, but negotiated : analyzing integration of policies in managing water resources in the Indian Himalayas using a Bayesian network
No full textAuthor name used in this publication: Saravanan. V.SubramanianAuthor name used in this publication: David, Ip2009-2010 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishedGreen (AAM
A web-based screening tool for near-port air quality assessments
No full textAuthor(s): Isakov, Vlad; Barzyk, Timothy M; Smith, Elizabeth R; Arunachalam, Saravanan; Naess, Brian; Venkatram, Akul
Electronic Photonic Circuit Design for RF Transceiver
No full textRF over fibre (RoF) based communication system combines features of mm-wave and optical fibre communication. The RoF-based system has the advantage of both optical fibre systems (such as high bandwidth, signal transparency, low-loss and lesser weight of optical fibre) and RF systems (such as mobility and distribution). This RoF transceiver can be made more efficient by combining it with beamforming techniques and reconfigurability. Spatial beamforming techniques help in minimizing the interference in the wavefront by active beam alignment in the transmit and receive paths. Even though, the realization of transceiver chip with electronics and optical circuits is very challenging, it can potentially be realized in future using silicon-photonics technology. This technology is commercially viable for mass-production, since it is compatible with matured CMOS technology. This dissertation presents different design techniques and architectures of electronic components, such as, phase-shifter, attenuator, SPDT switch and TIA, for improving the performance of RoF based phased array transceiver using CMOS/BiCMOS technologies.
The trade-offs in the beamforming architectures have been first discussed in terms of their performance, circuit design complexity and realization cost. Overview of the functionalities and implementation of each electronics and photonics component used in the RoF based phased array transceiver has been presented. The research objectives have been outlined based on the available literature and implementation strategy.
The design of a 7-bit S-band digital passive phase shifter realized using CMOS 65 nm technology is first described. This phase-shifter utilizes novel switched delay network- based topologies for 5.625 degree and 2.8 degree phase bit, along with modified switched filter topologies for other phase-bits. The experimental results of the fabricated chip have shown 7-bit performance with an average insertion loss, root mean square (RMS) phase error and RMS amplitude error of ≤ 11 dB, ≤ 2.0 degree and ≤ 0.6 dB, respectively, with S11 ≥ 7.5 dB and S22 ≥ 14.5 dB across the target frequency band of 2.6 to 3.2 GHz. In addition, design techniques for the realization of broadband switched type IF passive phase-shifter have been presented. These techniques include custom design of a two-metals inductor, a cross-coupled inductor with centre taping and setting the DC bias at RF input/output to 0 V. Design and EM simulation results of a 22.5 degree passive phase-shifter, with and without these broadband techniques, have been discussed for demonstrating their validity. The proposed topology has shown broadband phase-shifter response across 2.5-to-8.0 GHz, with RMS phase error, amplitude error and insertion loss of 9.2 dB.
The design details and simulations of an 8-bit S-band digital passive attenuator, and proposal of a bit topology selection algorithm to achieve low RMS phase error and low amplitude error have been described next. This attenuator has been designed by using new phase compensated Π−, T−and T −bridge attenuator bit topologies for 32 dB to 0.25 dB attenuator bits, and adopting the bit topology selection algorithm. This attenuator has been designed using 65 nm CMOS technology, and its performance has been characterized with the help of exhaustive post-layout simulation in 2.8 GHz to 4.0 GHz frequency band. The designed attenuator has demonstrated significant improvement in performance with 8-bit attenuation accuracy, insertion-loss of ≤ 5.1 dB, RMS amplitude error of ≤ 0.1 dB, RMS phase error of ≤ 0.78 degree, and S11/S22 > 12 dB in 2.8 GHz to 4.0 GHz frequency band.
Thirdly, the design details of a fully differential Ka-band single-pole double-throw (SPDT) switch with virtual grounding, realized using 0.13 μm SiGe BiCMOS technology, have been discussed. This SPDT switch with fully differential topology inherently offers cancellation of common-mode disturbance and has high P−1dB. Further, an asymmetri- cally tapered inductor utilization has been introduced in this SPDT switch with a normal spiral inductor to reduce the layout area of the SPDT switch. Experimental results of the fabricated differential SPDT switch with normal spiral inductor has exhibited the best insertion loss of 2.9 dB and an isolation of -39 dB in 25 GHz to 40 GHz frequency-band, with input P−1dB of 12.6 dBm at 34 GHz and 0.47 mm2 chip-area. Compact differential SPDT switch with asymmetrically tapered inductor has occupied an area of 0.11 mm^2 in the layout and demonstrated superior insertion loss of 1.8 dB and isolation of -39 dB in the same frequency-band with improved input P−1dB of 14.1 dBm at 34 GHz. For further improving the input P−1dB of this SPDT switch, a design of SPDT switch design 3 with pass-gate switch configuration has been presented next. In this design 3, pass-gate tran- sistor terminals biasing is set to 0 V through a 20 KΩ resistance for reducing variations in device parasitics. This SPDT switch has demonstrated a minimum insertion-loss of 1.29 dB, maximum isolation of 41.2 dB and S11/S22 better than 12 dB across the frequency band of operation. This SPDT switch has also shown input P1dB of 15.4 dBm with a layout area of 0.11 mm^2
Design trade-offs, mathematical analysis and circuit architecture of a new low-noise, broadband single-stage transimpedance amplifier (TIA) using 130 nm bipolar complemen- tary metal-oxide-semiconductor (BiCMOS) has been next presented in detail. This TIA is designed as a Common-emitter (CE) shunt-shunt feedback topology with active inductor peaking, and scalable bandwidth enabling better noise, gain and driving capability. The validity of the active inductive peaking and mathematical analysis has been proved with the help of simulations and measurement results. The experimental results of Ku-band TIA (10 MHz to 14 GHz) designed using this architecture have shown a transimpedance gain of 53.2 dBΩ, input-referred current noise of 16.8 pA/√Hz with power consumption of 9.8 mW. Further, another TIA covering K- and Ka-bands (10 MHz to 35 GHz) has been presented to demonstrate the architecture’s adaptability for higher bandwidth. This K-and Ka-bands TIA has demonstrated a transimpedance gain of 33.4 dBΩ, input-referred current noise of 29.4 pA/√Hz with a power consumption of 28.1 mW in the post-layout simulation results, and occupies the same chip area as that of Ku-band TIA, i.e., 0.1 × 0.21 mm^2.
Finally, the feasibility of a 35 GHz RoF communication link has been presented with the help of an experimental demonstration of a 2D integrated RoF photonic transmitter link. This demonstration has addressed the challenges associated with 2D integration. This test-jig has been assembled on a Kovar substrate using a silicon-photonics microring modulator die, driver amplifier die, and interconnected using 50 Ω transmission line. The integrated transmitter link has demonstrated the measured electro-optical (S21) band- width of 35 GHz, the maximum gain of 12.4 dB, RF matching at driver amplifier input in the range of -5 dB to -42 dB and optical matching at microring modulator input in the range of -8 dB to -21 dB for 50 Ω load across 35 GHz frequency bandwidth
Performance and Emission Characteristics of Pyrolysed Fuel of Tyre Blended with Diesel in Diesel Engine
No full textThe waste management of scrap tyre causes impact on environment due to its non degradable property. Therefore the recycling of tyre scrap is to be considered for improving the energy conversion from solid waste management. The objective of this project is to investigate the performance and emission characteristics of diesel blended with Tyre Prolysis Oil TPO in direct injection DI diesel engine. The tyre oil obtained at 713 K through pyrolysis process of waste tyre. The synthesized oil is then processed by desulphurization to reduce the sulphur content and transesterification for blending it with diesel. The various blends of composition 10 TPO and 90 diesel, 20 TPO and 80 diesel is prepared. Through these blends the improvement of performance and emission characteristics such as NOX, CO2, HC were identified and compared with conventional diesel fuel. K. Saravanan | Pon. Azhagiri | Dr. T. Senthil Kumar "Performance and Emission Characteristics of Pyrolysed Fuel of Tyre Blended with Diesel in Diesel Engine" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: https://www.ijtsrd.com/papers/ijtsrd14362.pd
Wide Temperature Operation of 40-Gb/s 1550-nm Electroabsorption Modulated Lasers
No full textElectroabsorption modulated lasers (EMLs) exploiting the quantum confined Stark effect need thermoelectric coolers to achieve stable output power levels and dynamic extinction
ratios. Temperature-independent operation is reported between 20 C and 70 C for InGaAlAs–InP-based monolithically integrated 1550-nm EMLs exploiting a shared active area at 40 Gb/s by actively controlling the electroabsorption modulator bias voltage. Dynamic extinction ratios of at least 8 dB and fiber-coupled mean modulated optical power of at least 0.85 mW
are obtained over the mentioned temperature range
TIN OXIDE MODIFIED SILICON NANOWIRES ON SILICON CHIP AS AMMONIA SENSOR
No full textTitle: TIN OXIDE MODIFIED SILICON NANOWIRES ON SILICON CHIP AS AMMONIA SENSOR
Authors: Saravanan Yuvaraja1,2, Hrishikesh Dhasmana2, Amit Kumar2, Vivek Kumar2, Abhishek Verma2, V. K. Jain2 and Khaled Salama1.
Section 1: HOW YOU ARE EXPOSED TO AMMONIA ?
Section 2: HOW AMMONIA AFFECTS YOUR HEALTH ?
Section 3: WE CAN SAVE YOU FROM AMMONIA EXPOSURE
Level 1: Synthesis
Level 2: Performance analysis
Level 3: Prototype demonstration
Attention: Both Synthesis process flow and Gas sensing mechanism concept of the reported device architecture is presented in the vide
Comments on: High fat intake leads to acute postprandial exposure to circulating endotoxin in type 2 diabetic subjects.
No full textComments on: Harte AL, Varma MC, Tripathi G, McGee KC, Al-Daghri NM, Al-Attas OS, Sabico S, O'Hare JP, Ceriello A, Saravanan P, Kumar S, McTernan PG. High fat intake leads to acute postprandial exposure to circulating endotoxin in type 2 diabetic subjects. Diabetes Care. 2012 Feb; 35(2): 375-8
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