Reinforcement Learning based NLP

In the field of Natural Language Processing (NLP), reinforcement learning (RL) has drawn attention as a viable method for training models. An agent is trained to interact with a linguistic environment in order to carry out a given task using RL- based NLP, and the agent learns from feedback in the form of rewards or penalties. This method has been effectively used for a variety of linguistic problems, including text summarization, conversation systems, and machine translation. Sequence-to- sequence Two common methods used in RL-based NLP are reinforcement learning and deep reinforcement learning. Sequence-to-sequence While deep reinforcement learning includes training a neural network to discover the optimum strategy for a language challenge, reinforcement learning (RL) trains a model to create a series of words or characters that most closely matches a goal sequence. In several linguistic challenges, RL-based NLP has demonstrated promising results and attained cutting-edge performance. There are still issues to be solved, such as the need for more effective exploration tactics, data scarcity, and sample efficiency. In summary, RL-based NLP represents a potential line of inquiry for NLP research in the future. This method outperforms more established NLP strategies in a variety of language problems and has the added benefit of being able to improve over time with user feedback. To further enhance RL-based NLP's effectiveness and increase its applicability to real-world settings, future research should concentrate on resolving the difficulties associated with this approach.Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP) © Copyright: All rights reserved

Living with landslides: Integrating knowledge for landslide risk reduction in rural Nepal

Nepal is a country highly exposed to the impact of climate change, a situation that is set against the ongoing experience of year-on-year losses from environmental disasters. Of these, landslides result in the highest number of fatalities, a situation that is attributed to a combination of factors: the monsoon climate, the steep unstable topography and a large and often highly vulnerable rural population. Unfortunately, Nepal’s experience in this respect is also of global significance: between 2004 and 2016 the country accounted for approximately 10% of all rainfall-triggered landslide fatalities, despite occupying less than 0.1% of the Earth’s land area. The majority of these incidents are experienced as a result of relatively small-scale localised landslides, the perennial nature of which means they are often seen as part of life, despite their significant chronic impact on people’s livelihoods. This chronic background hazard was then overprinted by the Mw7.8 2015 Gorkha earthquake, which resulted in a significant number of fatalities and had a further devastating impact on people’s livelihoods. It also caused additional landslides across Central and Western Nepal. Six years later, these impacts are still being felt. As a result, there is a real need to build greater resilience to landslide risks in rural Nepal; however, efforts to do this lack innovation, and are relatively limited in number and success. To tackle the problem, this research presents a study of a valley badly hit by the 2015 earthquake where the residents have to live alongside active landslides. The research starts with a household survey to explore the depth of understandings of landslides, the risks they pose and how these features in day-to-day lives. A participatory mapping exercise follows; this seeks to explore in more detail the geographical dimensions of local risk awareness, highlighting several knowledge gaps with regard to why, where and when landslides may occur. Finally, the research presents the development of a novel live demonstration system, which models an actively failing slope to allow participants to gain more insight into the mechanisms of the landslides around them and the risks they pose. Critically, the demonstrator provides a way of visualising and evaluating potential forms of landslide mitigation, such as monitoring or small-scale engineering interventions, that could help to reduce these risks in future. The thesis concludes by considering how this approach might be developed further as a means of reducing landslide risks in rural Nepal

Modeling and Simulation of Subthreshold Characteristics of Short-Channel Fully-Depleted Recessed-Source/Drain SOI MOSFETs

Non-conventional metal-oxide-semiconductor (MOS) devices have attracted researchers‟ attention for future ultra-large-scale-integration (ULSI) applications since the channel length of conventional MOS devices approached the physical limit. Among the non-conventional CMOS devices which are currently being pursued for the future ULSI, the fully-depleted (FD) SOI MOSFET is a serious contender as the SOI MOSFETs possess some unique features such as enhanced short-channel effects immunity, low substrate leakage current, and compatibility with the planar CMOS technology. However, due to the ultra-thin source and drain regions, FD SOI MOSFETs possess large series resistance which leads to the poor current drive capability of the device despite having excellent short-channel characteristics. To overcome this large series resistance problem, the source/drain area may be increased by extending S/D either upward or downward. Hence, elevated-source/drain (E-S/D) and recessed-source/drain (Re-S/D) are the two structures which can be used to minimize the series resistance problem. Due to the undesirable issues such as parasitic capacitance, current crowding effects, etc. with E-S/D structure, the Re-S/D structure is a better choice. The FD Re-S/D SOI MOSFET may be an attractive option for sub-45nm regime because of its low parasitic capacitances, reduced series resistance, high drive current, very high switching speed and compatibility with the planar CMOS technology. The present dissertation is to deal with the theoretical modeling and computer-based simulation of the FD SOI MOSFETs in general, and recessed source/drain (Re-S/D) ultra-thin-body (UTB) SOI MOSFETs in particular. The current drive capability of Re-S/D UTB SOI MOSFETs can be further improved by adopting the dual-metal-gate (DMG) structure in place of the conventional single-metal-gate-structure. However, it will be interesting to see how the presence of two metals as gate contact changes the subthreshold characteristics of the device. Hence, the effects of adopting DMG structure on the threshold voltage, subthreshold swing and leakage current of Re-S/D UTB SOI MOSFETs have been studied in this dissertation. Further, high-k dielectric materials are used in ultra-scaled MOS devices in order to cut down the quantum mechanical tunneling of carriers. However, a physically thick gate dielectric causes fringing field induced performance degradation. Therefore, the impact of high-k dielectric materials on subthreshold characteristics of Re-S/D SOI MOSFETs needs to be investigated. In this dissertation, various subthreshold characteristics of the device with high-k gate dielectric and metal gate electrode have been investigated in detail. Moreover, considering the variability problem of threshold voltage in ultra-scaled devices, the presence of a back-gate bias voltage may be useful for ultimate tuning of the threshold voltage and other characteristics. Hence, the impact of back-gate bias on the important subthreshold characteristics such as threshold voltage, subthreshold swing and leakage currents of Re-S/D UTB SOI MOSFETs has been thoroughly analyzed in this dissertation. The validity of the analytical models are verified by comparing model results with the numerical simulation results obtained from ATLAS™, a device simulator from SILVACO Inc

Cloud Metering and Monitoring

For Service Oriented Infrastructures (SOI) and Cloud services, monitoring and metering are crucial tasks. For the proper execution of cloud applications & the monitoring of SLA compliance, the data gathered through monitoring is required. The motivations for and challenges in monitoring and metering cloud systems are discussed. The methods for monitoring the network and execution environment on virtualized infrastructures will be discussed together with the monitoring tools that are now available on various commercial and research platforms. Every distributed computing system has a basic feature that includes monitoring chores. Every service should be watched over in order to evaluate its effectiveness and enable remedial measures in the event of failure. A functional snapshot of the system's behaviour along the time axis is what monitoring data reflects. Such information is essential for pinpointing the source of issues or for fine-tuning various system components. For example, failure detection and recovery procedures require a monitoring component to determine whether to restart a specific server or subsystem based on the data gathered by the monitoring system.Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP) © Copyright: All rights reserved

VISCOUS FLOW AND HEAT TRANSFER IN A VERTICAL CHANNEL WITH DEFORMABLE POROUS LAYER MEDIUM

Steady flow of a viscous fluid in a vertical deformable porous layer bounded by.............

Computational study of pristine and titanium-doped sodium alanates for hydrogen storage applications

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained unanswered regarding the role of Ti in reversible hydrogen storage of sodium alanates with improved thermodynamics and kinetics of hydrogen desorption. The first question is about the position of transition metal dopants in the sodium aluminum hydride lattice. The position is investigated by identifying the possible sites for titanium dopants in NaAlH4 lattice and studying the structure and dynamics of possible compounds resulting from titanium doping in sodium alanates. The second question is the role of titanium dopants in improved thermodynamics of hydrogen desorption in Ti-doped NaAlH4. Though it is accepted in the literature that formation of TiAl alloys (Ti-Al and TiAl3) is favorable, reaction pathways are not clearly established. Furthermore, the source of aluminum for Ti-Al alloy formation is not clearly understood. The third question in this area is the role of titanium dopants in improved kinetics of hydrogen absorption and desorption in Ti-doped sodium alanates. This study is directed towards addressing the three longstanding questions in this area. Thermodynamic and kinetic pathways for hydrogen desorption in pristine NaAlH4 and formation of Ti-Al alloys in Ti-doped NaAlH 4, are elucidated to understand the underlying mechanisms of hydrogen desorption. Density functional theory formalism as implemented in CASTEP (Cambridge Serial Total Energy Package) is used to study the structure and energetics of pristine and Ti-doped sodium alanates. From investigations of various models of sodium alanates with Ti dopants, it is shown that the difference between the energy required for Ti→SNa (Ti-substituted Na at the lattice site on the surface) and Ti→TI (Ti placed on top of the surface interstitial SI site) is 0.003 eV atom-1, and is minimal compared to other models. Since less energy is required for Ti→S Na and Ti→TI, these two sites (SNa and T I) would be preferred by the Ti dopants. In Ti→SNa model, Ti is coordinated to two aluminum and seven hydrogen atoms resulting in the possible formation of a TiAl2H7 complex. At elevated temperatures (423 and 448 K), the number of aluminum atoms coordinating with titanium in the complex increase from two (at distances in the 2.6-2.7 Å range) to five (at distances in the 2.6-2.7 Å range). Besides the formation of a Ti-Al-H complex, Al-Al association (with a 2.97 Å bond length) is also seen from the DFT-MD results. In the case of Ti→TI, Ti is coordinated to two aluminum and two hydrogen atoms resulting in the possible formation of a TiAl2H2 complex. TiAl2 H2 complex becomes TiAl3H6 and TiAl 3H7 at elevated temperatures of 423 and 448 K, respectively. The investigation of thermodynamics pathways in Ti-doped sodium alanates illustrates a three step reaction pathway to the formation of TiAl3 (Ti and AlH3 after the first reaction, TiAl after the second and finally TiAl3). This investigation also suggests aluminum in its +3 oxidation state present in aluminum hydride species is responsible in the formation of Ti-Al alloys. From kinetics studies, the proposed mechanism is related to transition from AlH4- to AlH6 3-. The rate limiting step is determined to be associated with hydrogen evolution from association of AlH3 species nucleating aluminum phase. This step is 15 kJ/mol higher than the nearest highest barrier in the reaction path related to transition from AlH52- to AlH63-. From the DFT-MD simulations, it is observed that the titanium dopants are present on the surface during the entire simulation time and exhibit the role in catalytic splitting of hydrogen from surrounding AlH4groups. Besides the catalytic role, Ti dopants also form bonds with Al, and we also see that the AlH4 groups on the surface and that are present in the sub-surface layers are drawn towards the Ti dopants. This association of Al around titanium indicates the initiation of Al nucleation site facilitated by Ti dopants residing on the surface

A domino palladium catalysis: Synthesis of 7-methyl-5 H -dibenzo[ a, c ][7] annulen-5-ones

A domino Pd-catalyzed reaction of 1-(2-bromophenyl)ethanones for the synthesis of novel 7-methyl-5H-dibenzo[a,c][7]annulen-5-ones, a carbon core structure present in colchicinoid natural products, is presented. The reaction is proposed to proceed via intermolecular homobiaryl coupling and intramolecular aldol condensatio

Formation of bi-aryls via a domino palladium catalysis

Synthesis of bi-aryls via a domino Pd-catalyzed reaction of 1-(2-bromophenyl)-2-methylpropan-1-ones/(2-bromophenyl)(cyclohexyl)methanones is presented. The mechanism of the reaction is believed to proceed through a five membered palladacycle that combines with a second molecule of halo-arene to yield the bi-aryls. This method is quite successful to deliver highly sterically crowded bi-aryls with dense functionalities on the aromatic rings

Palladium-catalyzed selective α-arylation of ortho -bromoacetophenones

Synthesis of 1-(2-bromophenyl)-2-phenylethanones via an intermolecular Pd-catalyzed α-arylation of 1-(2-bromophenyl)ethanones is presented. The method relies on selective C-H activation (α-arylation) of relatively more reactive external iodo-arenes as coupling partners without affecting the bromo-substituent. Moreover, the scope and generality of the method has been well studied by employing the reaction with iodo-arenes as coupling partners bearing electron-withdrawing, simple, and electron-donating groups on the aromatic ring