Hot Surface Ignition

Undesirable hot surface ignition of flammable liquids is one of the hazards in ground and air transportation vehicles, which primarily occurs in the engine compartment. In order to evaluate the safety and sustainability of candidate replacement fuels with respect to hot surface ignition, a baseline low lead fuel (Avgas 100 LL) and four experimental unleaded aviation fuels recommended for reciprocating aviation engines were considered. In addition, hot surface ignition properties of the gas turbine fuels Jet-A, JP-8, and JP-5 were measured. A test apparatus capable of providing reproducible data was designed and fabricated to experimentally investigate the hot surface ignition characteristics. A uniform surface temperature stainless steel plate simulating the wall of a typical exhaust manifold of an aircraft engine was used as the hot surface. Temperature uniformity of ±5°C was achieved on the stainless steel plate by virtue of its being bolted to a copper plate in which five automatically controlled 1000 W electrical cartridge heaters were inserted. A programmable syringe pump was used to dispense ~25 μL fuel drops onto the hot surface. Testing was performed in a quiescent environment with the exception of a mild upward flow created by an exhaust fan aiding the buoyant plume created by the hot plate. Ignition and flame propagation events were recorded using visible and mid-infrared still and video imaging. The ignition and flame propagation events are transient and occur at randomly distributed locations on the hot surface. To characterize the ignition event statistically, the surface temperature leading to at least one ignition out of the number of drops and the surface temperature resulting in the ignition of all of the drops were recorded. The results of the experiment confirmed that the experimental variations in the drop size, drop velocity, plume characteristics, surface properties including temperature changes, and the nonlinear dependence of temperature of the chemical reaction rate lead to the probabilistic nature of the ignition event. The results of the experiment are of practical value in designing vehicular ignition and safety systems

Revisiting Low Resource Status of Indian Languages in Machine Translation

Indian language machine translation performance is hampered due to the lack of large scale multi-lingual sentence aligned corpora and robust benchmarks. Through this paper, we provide and analyse an automated framework to obtain such a corpus for Indian language neural machine translation (NMT) systems. Our pipeline consists of a baseline NMT system, a retrieval module, and an alignment module that is used to work with publicly available websites such as press releases by the government. The main contribution towards this effort is to obtain an incremental method that uses the above pipeline to iteratively improve the size of the corpus as well as improve each of the components of our system. Through our work, we also evaluate the design choices such as the choice of pivoting language and the effect of iterative incremental increase in corpus size. Our work in addition to providing an automated framework also results in generating a relatively larger corpus as compared to existing corpora that are available for Indian languages. This corpus helps us obtain substantially improved results on the publicly available WAT evaluation benchmark and other standard evaluation benchmarks.Comment: 10 pages, few figures, Preprint under revie

Investigation of Fire Safety Characteristics of Alternative Aviation Fuels

Due to the depletion of fossil fuel reserves and emission challenges associated with its usage, there is a need for alternative aviation fuels for future propulsion. The alternative fuels with handling, storage and combustion characteristics similar to conventional fuels can be used as “drop-in” fuels without significant changes to the existing aviation infrastructure. Fire safety characteristics of alternative aviation fuels have not been studied intensively and therefore research is needed to understand these characteristics. In this study, fire safety characteristics namely hot surface ignition (HSI) and flame spread phenomena are investigated for alternative aviation fuels. HSI is defined as the process of a flammable liquid coming in contact with a hot surface and evaporating, mixing and reacting with the surrounding oxidizer with self-supporting heat release (combustion). If all the conditions are adequate, the fuel may completely turn into combustion products following the ignition process. This work presents results from more than 5000 ignition tests using a newly developed reproducible test apparatus. A uniform surface temperature stainless steel plate simulating the wall of a typical exhaust manifold of an aircraft engine is used as the hot surface. Ignition tests confirmed that the ignition event is transient and initiates at randomly distributed locations on the hot surface. The results show many significant differences and some similarities in the ignition characteristics and temperatures of the different fuels. In this work, hot surface ignition temperatures (HSITs) are measured for nine hydrocarbon liquids. Five of these fuels are piston engine based, three fuels are turbine-engine based and one fuel is a pure liquid, heptane. The piston engine based fuels are given by FAA and are confidential and hence labeled as test fuels A, B, C, D for this study. The HSITs of these fuels are measured and compared against a baseline fuel 100 LL aviation gasoline (100LL Avgas). HSITs of conventional turbine engine based fuels namely Jet-A, JP-8, and JP-5 are also measured. Flame spread along liquid fuel has been one of the important combustion phenomena that still requires more in-depth research and analysis for the deep understanding of the chemical processes involved. Flame spread rate determines how fast the flame spreads along the fuel surface and it is an important parameter to study for fire safety purposes. For the flame spread rates study, a novel experimental apparatus is designed and fabricated. The experimental apparatus consists of a rectangular pan, a fuel heating system, an autonomous lid actuation system, a CO2 fire extinguisher system, and a laser ignition system. The flame spread phenomenon is studied for a conventional aviation fuel namely, Jet-A and three alternative aviation fuels namely, hydro-processed ester fatty acids (HEFA-50), Fischer-Tropsch – IPK (FT-IPK) and synthetic iso-paraffin (SIP). The experiments are conducted for a wide range of initial fuel temperatures ranging from 25°-100°C for Jet-A, HEFA-50, FT-IPK and from 80-140°C for SIP as the flash-point of SIP is 110°C and is ~3 times higher than that of other three fuels

Validation of ICMR index for identification of dental fluorosis in epidemiological studies

Background & objectives: The Indian Council of Medical Research (ICMR) formulated a Task Force on dental fluorosis and recommended the subgroup to develop a simplified index for identification and grading of dental fluorosis to be used by the health workers. This study was conducted to pre-test the ′ICMR Index for Dental Fluorosis′ in the field to check its reliability and reproducibility. Methods: A total of 600 photographs were taken, 150 in each grade of fluorosis by screening 14-17 yr school children from eight schools of Hisar (Haryana) and South west Delhi. Eighty photographs were finalized (20 in each grade) before calibration to be used for training of field workers. Calibration exercise was conducted involving the five member survey team on 100 diagnosed cases of dental fluorosis. The members again screened 74 children with dental fluorosis in the field to categorize in to different grades of fluorosis for assessment of inter-examiner reliability. Results: The ICMR criteria showed more difference in agreement in very mild and mild categories during calibration. The inter-examiner reliability (κ) ranged from 0.59-1. The criteria was further modified and inter- examiner reliability (κ) found to be 0.83-0.98 which was almost perfect agreement. Interpretation & conclusions: The tool developed by the ICMR to assess dental fluorosis can be used in a field set up by non-dental personnel reliably with high degree of reproducibility

Structural and functional implication of RAP80 ΔGlu81 mutation.

Receptor Associated Protein 80 (RAP80) is a member of RAP80-BRCA1-CCDC98 complex family and helps in its recruitment to the DNA damage site for effective homologous recombination repair. It encompasses two tandem UIMs (UIM1 and UIM2) motif at its N-terminus, which interact with K-63 linked polyubiquitin chain(s) on H2AX and thereby assemble the RAP80-BRCA1 complex at the damage site. Nevertheless, how RAP80 helps in the structural integrity of BRCA1 complex is still elusive. Considering the role of RAP80 in the recruitment of BRCA1 complex at the DNA damage site, we attempted to explore the molecular mechanism associated with RAP80 and mutation that causes chromosomal aberrations due to its loss of function. There is a significant loss in structural characteristics of RAP80 ΔE81, which impairs its binding affinity with the polyubiquitin chain. This leads to the defective recruitment of RAP80 and BRCA1 complex at the DNA damage site. The results presented here are very useful in understanding the cause of various repair defects (chromosomal aberration) that arise due to this mutation. Comparative study of wild type and ΔE81 could be helpful in designing the small molecules that can potentially compensate the deleterious effect(s) of ΔE81 and hence useful for therapeutic application

Binding interaction of RAP80 UIMs and ΔE81 with Di-Ub (K-63 linked).

<p>(<b>A</b>) Structure of Di-Ub (K-63 linked)-RAP80 UIMs (79–124) wild type (PDB ID: 2RR9), and (<b>B</b>) Di-Ub (K-63 linked)-RAP80 (79–124) UIMs ΔE81. Wild type and Di-Ub (K-63 linked) complex is stabilized by weak intermolecular interactions. α-helix of RAP80 (79–124) UIM ΔE81 was found to be distorted. (<b>C</b>) multiple sequence alignment of UIMs region showed it's highly conserved nature in various species. Glu 81 residue is highlighted in red color.</p

Molecular weight estimation of purified protein.

<p>Ve/Vo: Elution volume/Void volume ratio in gel filtration chromatography (superdex 200 16/60).</p>a<p>Determined from Protparam, Expasy.</p>b<p>Determined from standard myoglobin, ovalbumin, albumin, IgG, Ferritin.</p

Structure and stability analysis of RAP80 wild type and ΔE81.

<p>Secondary structural components and thermal stability of RAP80 wild type and ΔE81. (<b>A</b>) Overlay of Far-UV Circular Dichroism spectrum of wild type and ΔE81. Wild-type showed well-defined α/β characteristics compared to a random structure pattern of ΔE81. Thermal stability of RAP80 wild type. (<b>B</b>) Thermal denaturation of RAP80 wild type and ΔE81 using Circular Dichroism and (<b>C</b>) using ANS as extrinsic fluorophore in Fluorescence. Unfolded fractions were calculated and plotted against different temperatures. (<b>D</b>) Differential Scanning Calorimetry profile of RAP80 wild type. Protein showed a well-defined transition around 28°C.</p