Fire Safety Analysis of a Railway Compartment using Computational Fluid Dynamics

Trains are considered to be the safest on-land transportation means for both passengers and cargo. Train accidents have been mainly disastrous, especially in case of fire, where the consequences are extensive loss of life and goods. The fire would generate smoke and heat which would spread quickly inside the railway compartments. Both heat and smoke are the primary reasons of casualties in a train. This study has been carried out to perform numerical analysis of fire characteristics in a railway compartment using commercial Computational Fluid Dynamics code ANSYS. Non-premixed combustion model has been used to simulate a fire scenario within a railway compartment, while Shear Stress Transport k-ω turbulence model has been used to accurately predict the hot air turbulence parameters within the compartment. The walls of the compartment have been modelled as no-slip stationary adiabatic walls, as is observed in real life conditions. Carbon dioxide concentration (CO2), temperature distribution and air flow velocity within the railway compartment has been monitored. It has been observed that the smoke above the fire source flows to both sides of the compartment. The highest temperature zone is located downstream the fire source, and gradually decreases with the increase in the distance from the fire source. It can be seen that CFD can be used as an effective tool in order to analyse the evolution of fire in railway compartments with reasonable accuracy. The paper also briefly discusses the topical reliability issues

Changes in the electronic structure and properties of graphene induced by molecular charge-transfer

Interaction with electron donor and acceptor molecules such as aniline and nitrobenzene brings about marked changes in the Raman spectrum and the electronic structure of graphene, prepared by the exfoliation of graphitic oxide.Comment: 13 pages, 4 figure

The effects of rotational flow, viscosity, thickness, and shape on transonic flutter dip phenomena

The transonic flutter dip phenomena on thin airfoils, which are employed for propfan blades, is investigated using an integrated Euler/Navier-Stokes code and a two degrees of freedom typical section structural model. As a part of the code validation, the flutter characteristics of the NACA 64A010 airfoil are also investigated. In addition, the effects of artificial dissipation models, rotational flow, initial conditions, mean angle of attack, viscosity, airfoil thickness and shape on flutter are investigated. The results obtained with a Euler code for the NACA 64A010 airfoil are in reasonable agreement with published results obtained by using transonic small disturbance and Euler codes. The two artificial dissipation models, one based on the local pressure gradient scaled by a common factor and the other based on the local pressure gradient scaled by a spectral radius, predicted the same flutter speeds except in the recovery region for the case studied. The effects of rotational flow, initial conditions, mean angle of attack, and viscosity for the Reynold's number studied seem to be negligible or small on the minima of the flutter dip

Charge-transfer with graphene and nanotubes

Charge-transfer between electron–donor and –acceptor molecules is a widely studied subject of great chemical interest. Some of the charge-transfer compounds in solid state exhibit novel electronic properties. In the last two to three years, occurrence of molecular charge-transfer involving single-walled carbon nanotubes (SWNTs) and graphene has been demonstrated. This interaction gives rise to significant changes in the electronic properties of these nanocarbons. We examine charge-transfer phenomenon in graphene and SWNTs in this article in view of its potential utility in device applications

Head position change is not associated with acute changes in bilateral cerebral oxygenation in stable preterm infants during the first 3 days of life

OBJECTIVE: Several recent intraventricular hemorrhage prevention bundles include midline head positioning to prevent potential disturbances in cerebral hemodynamics. We aimed to study the impact of head position change on regional cerebral saturations (SctO2) in preterm infants (< 30 weeks GA) during the first three days of life. STUDY DESIGN: Bilateral SctO2 was measured by near infrared spectroscopy. The infant's head was turned sequentially to each side from midline (baseline) in thirty-minute intervals while keeping the body supine. Bilateral SctO2 before and after each position change were compared using paired t-test. RESULTS: In relatively stable preterm infants (gestational age 26.5±1.7 weeks, birth weight 930±220g; n=20), bilateral SctO2 remained within normal range (71.1% - 75.3%) when the head was turned from midline position to either side. CONCLUSION: Stable preterm infants tolerated brief changes in head position from midline without significant alternation in bilateral SctO2; the impact on critically ill infants needs further evaluation

Association of hospital resource utilization with neurodevelopmental outcomes in neonates with hypoxic-ischemic encephalopathy

IMPORTANCE: Intercenter variation exists in the management of hypoxic-ischemic encephalopathy (HIE). It is unclear whether increased resource utilization translates into improved neurodevelopmental outcomes. OBJECTIVE: To determine if higher resource utilization during the first 4 days of age, quantified by hospital costs, is associated with survival without neurodevelopmental impairment (NDI) among infants with HIE. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort analysis of neonates with HIE who underwent therapeutic hypothermia (TH) at US children\u27s hospitals participating in the Children\u27s Hospitals Neonatal Database between 2010 and 2016. Data were analyzed from December 2021 to December 2022. EXPOSURES: Infants who survived to 4 days of age and had neurodevelopmental outcomes assessed at greater than 11 months of age were divided into 2 groups: (1) death or NDI and (2) survived without NDI. Resource utilization was defined as costs of hospitalization including neonatal neurocritical care (NNCC). Data were linked with Pediatric Health Information Systems to quantify standardized costs by terciles. MAIN OUTCOMES AND MEASURES: The main outcome was death or NDI. Characteristics, outcomes, hospitalization, and NNCC costs were compared. RESULTS: Among the 381 patients who were included, median (IQR) gestational age was 39 (38-40) weeks; maternal race included 79 (20.7%) Black mothers, 237 (62.2%) White mothers, and 58 (15.2%) mothers with other race; 80 (21%) died, 64 (17%) survived with NDI (combined death or NDI group: 144 patients [38%]), and 237 (62%) survived without NDI. The combined death or NDI group had a higher rate of infants with Apgar score at 10 minutes less than or equal to 5 (65.3% [94 of 144] vs 39.7% [94 of 237]; P \u3c .001) and a lower rate of infants with mild or moderate HIE (36.1% [52 of 144] vs 82.3% [195 of 237]; P \u3c .001) compared with the survived without NDI group. Compared with low-cost centers, there was no association between high- or medium-hospitalization cost centers and death or NDI. High- and medium-EEG cost centers had lower odds of death or NDI compared with low-cost centers (high vs low: OR, 0.30 [95% CI, 0.16-0.57]; medium vs low: OR, 0.29 [95% CI, 0.13-0.62]). High- and medium-laboratory cost centers had higher odds of death or NDI compared with low-cost centers (high vs low: OR, 2.35 [95% CI, 1.19-4.66]; medium vs low: OR, 1.93 [95% CI, 1.07-3.47]). High-antiseizure medication cost centers had higher odds of death or NDI compared with low-cost centers (high vs. low: OR, 3.72 [95% CI, 1.51-9.18]; medium vs low: OR, 1.56 [95% CI, 0.71-3.42]). CONCLUSIONS AND RELEVANCE: Hospitalization costs during the first 4 days of age in neonates with HIE treated with TH were not associated with neurodevelopmental outcomes. Higher EEG costs were associated with lower odds of death or NDI yet higher laboratory and antiseizure medication costs were not. These findings serve as first steps toward identifying aspects of NNCC that are associated with outcomes

Influence of LD slag on iron ore sinter properties and productivity

Large amounts of slags from steel plants are produced through basic oxygen furnace and LD furnace. The main purpose of LD process is to convert the molten pig iron and steel scraps into high quality steel. In India, the generation of steel melting slag is over 4 to 4.5 Mt per annum. The amount of steel slags from different steel industries are 150–200 kg/t of steel produced. Disposal of large quantities of slag becomes a big environmental concern. JSW Steel Limited is a 7.0 Mtpa integrated steel plant and produces 3200 tons of total steel making slag per day and in that LD slag is 2000 to 2500 t/day. This LD slag consists of 45.75% CaO, 22.0 % Fe and 8.22% MgO. Thus, recycling of LD slag through the sintering process recovers lime, iron and magnesia and thereby saving of flux material and iron ore. Due to high content of CaO one can replace LD slag by limestone in sintering process. Detail investigation was carried out through lab scale studies for estimating the maximum permissible limits of usage of LD slag in sinter making and to know the influence of LD slag addition on sinter productivity and properties. Experiments were conducted using the LD slag in sinter making from 0 to 60kg/t of sinter. FeO content of the sinter decreased, sinter productivity increased with increase in LD slag addition. Decrease in FeO content is due to decrease in sinter bed temperature and increase in productivity is due to decrease in LOI content of the sinter mix and absence of weight loss due to calcination process. The sinter strength and RDI of the sinter deteriorated due to non availability of free CaO in LD slag and this reduces the formation of calcium ferrites phase and more Fe2O3 remains as free phase due to less reaction with CaO. From the test results it was found that 30 to 35 kg LD slag can be used per ton of sinter to get desired properties of the sinter

A novel dry method for surface modification of SU-8 for immobilization of biomolecules in Bio-MEMS

SU-8 has been primarily used for structural elements and microfludics components in MEMS. Microsystems for biological applications require immobilization of biomolecules on the MEMS structures. In order to functionalize SU-8 for such purposes, the surface needs to be modified. In this paper, we report a novel dry method of surface modification of SU-8 which is compatible with standard microfabrication techniques. The surface obtained by spin coating SU-8 (2002) on silicon wafer was modified by grafting amine groups using pyrolytic dissociation of ammonia in a hotwire CVD setup. To demonstrate the presence of amine groups on modified SU-8 surface, the surface characteristic after modification was assessed using Fourier transform infrared spectroscopy. The change in SU-8 surface morphology before and after surface modification was investigated using atomic force microscopy. To show the utility of this process for application in Bio-MEMS, SU-8 microcantilevers were fabricated and subjected to the same surface modification protocol. Following this, the cantilevers were incubated first in a suspension of human immunoglobulin (HIgG) and then in FITC tagged goat anti-human IgG in order to demonstrate the utility of the surface modification performed. The efficacy of the process was assessed by observing the cantilevers under a fluorescence microscope