726 research outputs found
2010 Seventh International Conference on Information Technology: New Generations
No full textIsaac Macwan (with Hassan Bajwa, Vignesh Veerapandian, and Xinghao Chen) is a contributing author, VHDL Implementation of High-Performance and Dynamically Configures Multi-port Cache Memory, pp. 1212-1216.https://digitalcommons.fairfield.edu/engineering-books/1057/thumbnail.jp
Tetrastemma freyae Chernyshev & Polyakova & Vignesh & Jain & Sanjeevi & Norenburg & Rajesh 2020, sp. nov.
No full textTetrastemma freyae sp. nov. (Fig. 1 A–G) Type material. Holotype No JLN1622.01 (NMNH), Kaneohe Bay, Oahu, Hawaii, July 2017, depth 3 m, live corals, coll. J.L. Norenburg. Paratype JLN1622.02 (NMNH), collected with holotype. Paratype No ZSI / MBRC /NE-356 (ZSI), Covelong (Kovalam) beach (12.7925ºN, 80.2530ºE), Tamil Nadu, India, mussel beds, intertidal, 16 December 2019, coll. M.S. Vignesh. Other material examined. Three specimens, Covelong (Kovalam), Tamil Nadu, India, mussel beds, intertidal, 21 February 2019. GenBank accession numbers. Holotype MT 247877 (COI), MT 247879 (H3); paratype MT 247878 (COI), MT 247880 (H3). Description. External features. Live specimens 2–5 сm long and up to 1 mm wide, with spatulate- to diamondshaped head, bearing four black eyes. Two anterior eyes not distinguishable being masked by patch of cephalic pigment. Oblique cephalic furrows in two pairs: posterior furrows located behind posterior pair of eyes and anterior pair immediately in front of posterior eyes. Body tapering posteriorly, with blunt-rounded tail. General body color pale yellowish, with a patch of black pigment on dorsal surface of head. Patch trapezoid or oval, slightly varying in shape between specimens. Deeply located white pigment (possibly cephalic glands) present near anterior and posterior margins of patch. Some specimens bear small irregularly spaced black spots located dorsally. In holotype, lateral gut pouches visible as two darker lines. Internal features (on squeezed live specimens). Rhynchocoel as long as body. Basis cylindrical, with truncated and widened posterior part, 105 µm long and 35 µm in maximum width; central stylet 80 µm long. Two accessory stylet pouches each containing two accessory stylets. Gut pouches deeply branched. Ovaries contain 1–2 ovules. Remarks. A total of 16 described Tetrastemma species have a pale general body color and a dark patch of pigment on the dorsal surface of the head. Four of these, Tetrastemma verinigrum Iwata, 1954, T. pseudocoronatum Chernyshev, 1998, T. pimaculatum Chernyshev, 1998, and T. olgarum Chernyshev, 1998, have been recorded from Asian waters. Some varieties of Tetrastemma nigrifrons (Coe, 1904) (formerly placed in Quasitetrastemma – see Chernyshev 2004) also have a similar color (see Zaslavskaya et al. 2010). These species possess pear- or ovalshaped basis of the central stylet, whereas the basis in the new species is cylindrical with a flared posterior margin. A similar basis is characteristic for species in the genus Zygonemertes Montgomery, 1897, as well as Tetrastemma albomaculatum Chernyshev, 2016. The latter species, unlike T. freyae, has a white spot on the head (Chernyshev 2016). As the obtained data show, not only the body color, but also the shape of the central stylet basis should be taken into account in ‘histology-free’ descriptions of the new species of Tetrastemma. DNA barcode analysis. Among the Pacific Tetrastemma species with a dark pigment patch on the head, COI sequences are known for T. pseudocoronatum, T. pimaculatum, T. olgarum, and T. nigrifrons. The p -distances be- tween these species and T. melanocephalum from the European coast are provided in Table 1. The samples of T. freyae from Hawaii and India have p -distances 1.3% for COI and 0.3% for H3, which warrant designating a single species despite the substantial geographical space between these findings. Etymology. The specific epithet honors Ms Freya Goetz (NMNH) for her invaluable assistance to JLN in support of his field and laboratory work.Published as part of Chernyshev, Alexei V., Polyakova, Neonila E., Vignesh, Mohandhas S., Jain, Ruchi P., Sanjeevi, Prakash, Norenburg, Jon L. & Rajesh, Rajaian P., 2020, A histology-free description of a new species of the genus Tetrastemma (Nemertea: Hoplonemertea: Monostilifera) from Hawaii and India, pp. 379-383 in Zootaxa 4808 (2) on pages 380-382, DOI: 10.11646/zootaxa.4808.2.10, http://zenodo.org/record/393345
Reconfigurable and Agile Legged-Wheeled Robot Navigation in Cluttered Environments With Movable Obstacles
No full textLegged and wheeled locomotion are two standard methods used by robots to perform navigation. Combining them to create a hybrid legged-wheeled locomotion results in increased speed, agility, and reconfigurability for the robot, allowing it to traverse a multitude of environments. The CENTAURO robot has these advantages, but they are accompanied by a higher-dimensional search space for formulating autonomous economical motion plans, especially in cluttered environments. In this article, we first review our previously presented legged-wheeled footprint reconfiguring global planner. We describe the two incremental prototypes, where the primary goal of the algorithms is to reduce the search space of possible footprints such that plans that expand the robot over the low-lying wide obstacles or narrow into passages can be computed with speed and efficiency. The planner also considers the cost of avoiding obstacles versus negotiating them by expanding over them. The second part of this article presents our new work on local obstacle pushing, which further increases the number of tight scenarios the planner can solve. The goal of the new local push-planner is to place any movable obstacle of unknown mass and inertial properties, obstructing the previously planned trajectory from our global planner, to a location devoid of obstruction. This is done while minimising the distance traveled by the robot, the distance the object is pushed, and its rotation caused by the push. Together, the local and global planners form a major part of the agile reconfigurable navigation suite for the legged-wheeled hybrid CENTAURO robot
How the planning, engineering and politics of transportation established, preserves and perpetuates the automobile city
No full textThesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning; and, (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis. Page [167] blank.Includes bibliographical references (p. 161-166).The last eight decades of urban transportation planning and engineering in the United States have been dominated by the hegemony of the automobile. Auto-oriented planning of the transportation and land use system has had a profound impact on the built environment both in greenfield developments and neighborhoods that predated the auto. The pedestrian quality of cities has been eroded by the automobile, and urban renewal in the United States erased many neighborhoods strongly oriented around walking and transit use. Equally pervasive as the auto itself is the place for the car in the institutional cultures and practices involved in shaping the city. The shortcomings of mobility-oriented transportation planning have been well critiqued, even from the very early days of Interstate building. In recent decades there has been a flurry of interest in articulating sustainable transportation policies to provide multi-modal accessibility and to consider the interactions between transportation, land use, and other policy realms such as health, energy, environment and equity. The current impending crisis of aging and ailing highway structures in the United States presents a momentous opportunity to reassess the need and purpose of such infrastructure, and to rebuild, reconceptualize, or remove it in a matter more consistent with current policy goals and planning processes - rather than the ones in place when initially built. Despite the interest, need and opportunity to reconceptualize aging infrastructure in America to support a more sustainable reshaping of land use and activity patterns, the potential to do so is heavily impaired by a transportation planning process that is still dominated by the tools, methods and assumptions, political biases, procedural failures, and instilled human behaviors of the first highway-building era. The McGrath Highway in Somerville, MA is used as a case study to discuss how persistence of 1950s technical, procedural and political dysfunctions threaten to undermine this opportunity. Short-term actions and strategies to avoid this impending fate are suggested for McGrath Highway with applicability to a wider national context of similar opportunities.by Vignesh Krishnamurthy.S.M.in TransportationM.C.P
Stability of excitons in double quantum well: Through electron and holes transmission probabilities
No full textEffect of non-parabolicity and confinement potential on exciton binding energy in a quantum well
No full textFerrotoroidic ground state in a heterometallic {CrIIIDyIII6} complex displaying slow magnetic relaxation
No full textToroidal quantum states are most promising for building quantum computing and information storage devices, as they are insensitive to homogeneous magnetic fields, but interact with charge and spin currents, allowing this moment to be manipulated purely by electrical means. Coupling molecular toroids into larger toroidal moments via ferrotoroidic interactions can be pivotal not only to enhance ground state toroidicity, but also to develop materials displaying ferrotoroidic ordered phases, which sustain linear magneto-electric coupling and multiferroic behavior. However, engineering ferrotoroidic coupling is known to be a challenging task. Here we have isolated a {CrIIIDyIII6} complex that exhibits the much sought-after ferrotoroidic ground state with an enhanced toroidal moment, solely arising from intramolecular dipolar interactions. Moreover, a theoretical analysis of the observed sub-Kelvin zero-field hysteretic spin dynamics of {CrIIIDyIII6} reveals the pivotal role played by ferrotoroidic states in slowing down the magnetic relaxation, in spite of large calculated single-ion quantum tunneling rates
In-Situ Infrared Spectroscopic Studies of Palladium Thin Films during CO2 Electro-Reduction
No full textAn exponential growth in CO2 concentration over the past few decades has led to an accelerated impact of climate change on planet earth. In a bid to curb these emissions, people across the globe are slowly transitioning towards renewable energy sources with battery technology aiding this growth. Given that battery technology is still in its nascent stage, the “Electrochemical reduction of CO2” could be a viable solution supporting it without decelerating the momentum gained towards renewable development. Although plausible, the direct reduction of CO2 to liquid fuels entails huge energy expenditure thus requiring the implementation of catalysts. Unique in its ability, palladium reversibly reduces CO2 to formic acid making it an interesting candidate for the reduction reaction. In addition to the production of formic acid, palladium is also know to produce carbon monoxide (CO) which completely deactivates the surface preventing further reactions from occurring. Thus the aim of the current study is focused on analysing the electrochemical reduction of CO2 on palladium thin films using surface enhanced infrared absorption spectroscopy to better understand the deactivation mechanisms of CO on the palladium thin film. The smoothness of the as- sputtered 15 nm palladium thin film with a RMS roughness of 0.511 nm and partially coalesced islands were ascertained, thus requiring surface activation to introduce the enhancement mechanism. Experimental analysis of CO2 reduction on the palladium thin film was performed to unearth significant insights through the combination of electrochemical analysis techniques with surface enhanced infrared absorption spectroscopy. Results obtained through implementation of these methodologies provided substantial information not only on the influence of the palladium-hydrogen system on the electrochemical reduction of CO2 but also on the impact of alkali metal cations on the palladium-hydrogen system and the CO2 reduction reaction over the sputtered palladium thin film. CO formation, accumulation and desorption coupled with hydrogen evolution and desorption were some of the few avenues that were enumerated upon during the experimental investigation. The identity of CO chemisorbed on the palladium thin film along with bicarbonate direct/ indirect reduction to form CO was confirmed through the utilization of N2 saturated C13 NaHCO3 solution. In addition to the analysis of the reduction reaction, emphasis on the oxidation of CO was also provided suggesting the formation of dense CO structures with the existence of strong CO dipole – dipole coupling on the palladium surface. Materials Science and Engineerin
Life Cycle Assessment (LCA) analysis of thin film Silicon-based HyET solar cells
No full textGiven the rising research of thin film solar cells in recent years, flexible technology has been proven to be more light weight and cost effective. As photovoltaics is increasingly becoming the front runner in sustainable energy production, concerns over the associated impacts of solar modules throughout their life cycle are also increasing. This study quantifies the environmental impacts through LCA analysis for Roll-to-Roll (R2R) production process of thin film flexible silicon-based solar modules manufactured by a Dutch company HyET in The Netherlands.This study considers three product lines over a life cycle demarcated into its manufacturing, encapsulation and installation. The three product lines (cases) are as follows.1. Single junction a-Si with 7% efficiency.2. a-Si/nc-Si tandem cell with 10% efficiency3. a-Si/nc-Si tandem cell with 12% efficiencyThe installation phase considers a rooftop setup of capacity of 2.1 kWp with Balance of System (BoS) components.LCA analysis is carried out on Simapro 9.1.0.11 following the guidelines and the framework of International Organization for Standardization ISO14044. The outcome of LCA analysis is measured in terms of Global Warming Potential (GWP), Primary Energy Demand (PED) and Energy Pay Back Time (EPBT). Ecoinvent 3.5 is used as the primary database for these analyses to select the inventory. GWP is assessed using the CML-IA baseline method while PED is assessed using Cumulative energy demand v1.11 method. Sensitivity analysis is done by changing the location of production and up-scaling capacity. The installation stage is observed to contribute the highest GWP and also has the highest PED on account of BoS components. The LCA analysis has demonstrated similar trends of GWP, PED for all three product lines. EPBT on the other hand, is longer for 10% tandem cell on account of relatively larger module area as compared to 12% tandem cell and also the relatively higher energy consumption as compared to the single junction cell. The choice of substrate material is seen to impact the assessment indicators significantly. Flexible glass is observed to be the optimal choice for large-scale production. The choice of encapsulant material also affects the indicators demonstrably. Sensitivity analysis shows a positive impact on the indicators through up-scaling, while the location is not established as a significant factor sufficiently under considered assumptions.This project describes about the Life Cycle Assessment analysis of thin film Silicon-based HyET solar cells and their comparison to different substrate technologiesElectrical Engineering | Sustainable Energy Technolog
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