Keyword Augmented Retrieval: Novel framework for Information Retrieval integrated with speech interface

Retrieving answers in a quick and low cost manner without hallucinations from a combination of structured and unstructured data using Language models is a major hurdle. This is what prevents employment of Language models in knowledge retrieval automation. This becomes accentuated when one wants to integrate a speech interface on top of a text based knowledge retrieval system. Besides, for commercial search and chat-bot applications, complete reliance on commercial large language models (LLMs) like GPT 3.5 etc. can be very costly. In the present study, the authors have addressed the aforementioned problem by first developing a keyword based search framework which augments discovery of the context from the document to be provided to the LLM. The keywords in turn are generated by a relatively smaller LLM and cached for comparison with keywords generated by the same smaller LLM against the query raised. This significantly reduces time and cost to find the context within documents. Once the context is set, a larger LLM uses that to provide answers based on a prompt tailored for Q\&A. This research work demonstrates that use of keywords in context identification reduces the overall inference time and cost of information retrieval. Given this reduction in inference time and cost with the keyword augmented retrieval framework, a speech based interface for user input and response readout was integrated. This allowed a seamless interaction with the language model

A novel Thermocouple for Ultra High Temperature applications : Design and Computational Analysis

The development of high temperature sensors for accurately measuring temperature has become critical for structural health monitoring of high temperature structures viz. gas turbines, furnaces and hypersonic space vehicles. Conventional thermocouples have limitations owing to the maximum operational temperature of metallic alloys. In this perspective, it is imperative to explore new material systems which can extend the operational range of thermocouples up to 2500K temperature. Current work investigates a novel thermocouple design which employs Zirconium diboride based ultra-high temperature ceramics for providing protection to metallic thermocouple wires in oxidizing environments in heat flux as high as 2.5MW/m(2) for up to 120s duration. The performance evaluation of this novel thermocouple design has been carried using Finite element based computational modelling. This demonstrates that the proposed thermocouple design has good sensitivity of 3 V/K in relevant hot environment

Thermo-structural design of ZrB2-SiC-based thermal protection system for hypersonic space vehicles

The leading edges of hypersonic space vehicle experience high temperature and stress due to prevailing aerothermodynamic conditions of extreme heat flux and pressure. The design of thermal protection system (TPS) to protect the metallic airframe structure can ensure longer life and reliability under flight conditions. The effective design of TPS system requires the precise quantitative understanding of thermo-mechanical stresses and deformation, which demands careful computational study under flight simulated conditions. In the above perspective, TPS design for a leading edge exposed to Mach 7 hypersonic flow for 250 seconds has been carried out by performing finite element-based thermo-structural analysis with pressure and heat flux estimated from computational fluid dynamics analysis (CFD). The fidelity and robustness of CFD scheme is established using grid independence and convergence analysis. CFD analysis effectively captures the formation of bow shock around the leading edge and stagnation region near its nose. For finite element analysis, high-quality structural elements have been generated using HyperMesh to precisely model the thermo-structural behavior of TPS. In our computational analysis, TPS is modeled as a three-layered system with outermost layer of ZrB2-SiC, middle layer of phenolic cork and innermost layer of Ti-alloy. The analytical values of spatial variation of temperature, stress components, and displacement across the TPS have been critically analysed to rationalise specific structural configuration for better thermo-structural stability. Together with temporal variation of temperature, the implication of such computational results has led us to propose a new design for TPS. The proposed TPS is capable of containing the stress and displacement within 32 MPa and 0.58 mm, respectively, when the leading edge is exposed to shock induced aero-thermal heating as high as 2.11 MW/m(2) and pressure of 72.8 kPa for a hypersonic cruise flight of 500 km range

Design of Thermal Barrier Coating System for Scramjet using Coupled Thermo-Structural Analysis

Thermal barrier coating (TBC) is essential for scramjet structure to protect the metallic structure from melting or developing high stress. In this perspective, a novel TBC system with multiple layers of ceramics: top layer, intermediate layer, bond coat over a suitable metal substrate has been proposed. First, material selection for TBC system has been carried out based on their thermal conductivity and maximum operational temperature. Then, an elaborate design methodology has been evolved to constrain the temperature of each layer within their operational limit and minimization of thermal mismatch. Different design parameters have been identified and iterative finite element based thermo-structural analyses have been carried out to optimize them and hence, limit metal substrate temperature within 1250 K and the maximum interfacial shear stress within 80 MPa, when exposed to heat flux as high as 1.5 MW/m(2) and pressure greater than 1.3 bars

Experimental and computational analysis of thermo-oxidative-structural stability of ZrB2-SiC-Ti during arc-jet testing

The development of new ultra-high temperature ceramics for thermal protection system (TPS) of hypersonic cruise and re-entry vehicles requires performance-qualification testing under simulated flight conditions. The present work, encompassing experiments and computational analysis, critically analyzes the thermo-oxidative-structural stability of flat surface disks of spark plasma sintered ZrB2-18SiC-xTi composites (x=0, 10, 20; composition in wt%) under arc jet flow with heat flux of 2.5 MW/m(2) for 30 seconds. Such testing conditions effectively simulate the aero-thermal environment in ground facility, as experienced by hypersonic vehicles. Based on the extensive XRD, SEM-EDS and electron probe microanalyzer based analysis of the surface/sub-surface of arc jet exposed ceramics, the oxidation mechanisms are qualitatively discussed. Importantly, thick oxide layers (similar to 400-950 mu m) were found to be adherent, thereby providing good structural stability of such ceramics for reusable TPS. The careful finite element (FE) analysis with high quality structural elements, being generated using Hyper Mesh, was conducted to understand the underlying reasons for observed oxidation. Such analysis allows us to determine the temporal evolution of through-thickness temperature distribution. FE-based calculations were subsequently validated using experimentally measured backwall temperatures. The thermodynamic feasibility of competing oxidation reactions at the analytically computed front wall temperatures was thereafter realistically assessed to support the oxidation mechanisms. Taken together, the present work provides guidelines for better understanding of the thermo-oxidative-structural stability of ceramics under arc jet testing and also establishes the good stability of ZrB2-18SiC-20Ti composites for potential application in TPS of hypersonic space vehicles

Development of ZrB2-SiC-Ti by multi stage spark plasma sintering at 1600 degrees C

Zirconium diboride based ceramics, owing to their superior high temperature properties are potential materials for use as leading edge components in hypersonic space vehicles. However, the difficulty in sintering these ultra high temperature ceramics limit their applications to some extent. Sintering of such materials is usually accomplished by resorting to advanced sintering techniques such as Spark Plasma Sintering (SPS) accompanied by sinter aids to improve the sinterability. In this backdrop, the current work investigates the effect of Ti addition on the mechanical properties and sinterability of ZrB2-based ceramic composites. Tailored addition of Ti to ZrB2-18 wt. % SiC baseline composites not only improves the densification but also increases hardness and indentation toughness, when sintered using Multi Stage Spark Plasma Sintering technique. Microstructure and X-ray diffraction analysis reveals the presence of ultrafine grains of ZrB2 and SiC, which is found to be effective in obtaining a good hardness (up to 29 GPa) and reliable indentation toughness (up to 9 MPa center dot m(1/2)). (C) 2016 The Ceramic Society of Japan. All rights reserved

Prefabricated Stock Trays for Impression of Auricular Region

The conventional methods of impression making for maxillofacial defects are cumbersome and time consuming for both patient and operator. This study focuses upon standardizing and simplifying the impression making methodology for auricular prosthesis with the help of prefabricated stock trays for auricular region. The stock trays were designed on positive replicas of anatomical structures, broadly divided into long and narrow, short and broad and long and broad ear. For each stock tray, impressions of auricle, of patients of different morphology were made with plastic funnels of different shape and size ensuring at least 6 mm of space between the anatomical part and inner surface of funnel and master cast was obtained. Subsequent adaptation of wax was done and fabrications of stock stainless steel trays were done. A standardized stock tray for making of auricular impressions was developed. From this innovative technical procedure it is possible to get an accurate impression of auricular defects now by the use of prefabricated stock trays rather than the cumbersome conventional method