Filmwise condensation on micro-fin surfaces produced by selective laser melting

This paper presents an experimental investigation on the condensation of steam on vertical flat surfaces with arrays of micro-fins. Three micro-fin surfaces (MF1, MF2 and MF3) of the same fin diameter and fin height but with different fin pitch were fabricated by selective laser melting. The surfaces were tested in a condensation chamber where the gravity driven condensate flow and vapor velocity are orthogonal to one another. The effects of fin pitch and vapor velocity on the heat transfer performances of the surfaces were examined. Our results suggest that fin pitch has significant influence on the condensate drainage path as compared to the increase in heat transfer area. In addition, above a certain wall subcooled temperature, the increase in vapor velocity also resulted in the systematic increase in condensation heat flux indicating the significant effects of vapor shear force. In all, up to 1.4 times enhancement in the heat transfer coefficient was achieved with the micro-fin surface with a fin pitch of 300 μm as compared to a plain Al-6061 surface at constant vapor velocity.Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .International centre for heat and mass transfer.American society of thermal and fluids engineers

Enhanced thermal performance of a water-cooled cold plate with porous inserts fabricated by selective laser melting

The paper presents an experimental investigation of the thermal and hydraulic performance of a new class of porous metallic foams with ordered arrangements of the Rhombi-Octet unit cell design for use in a water-cooled cold plate. Selective laser melting (SLM) was employed to fabricate the porous metallic foams of two different unit cell sizes. A closed-loop chilled water test facility was set up to perform the experimental investigation and the results of the SLM fabricated porous metallic foams were compared with those of a commercially available metallic foam of random tetrakaidecahedron-like unit cell structures. The permeability (K) and inertia coefficient (CE) of the various metallic foams were characterized using the Forchheimer-extended Darcy equation and it was determined that K can be enhanced by 3.3 times with an increase in unit cell size of the Rhombi-Octet design from 5 mm to 10 mm. In addition, the Rhombi-Octet metallic foam insert also exhibits up to 91% enhancement in the heat transfer coefficient (have) as compared to the empty channel cold plate and up to 47% as compared to the commercial metallic foam insert.Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .International centre for heat and mass transfer.American society of thermal and fluids engineers

Mapping Strategic Goals and Operational Performance Metrics for Smart Manufacturing Systems

AbstractThe complexity of the relationship of strategic goals to operational performance across the many levels of a manufacturing system inhibits the realization of Smart Manufacturing Systems (SMS). This paper proposes a method for identifying what aspects of a manufacturing system should be addressed to respond to changing strategic goals. The method uses standard techniques in specifying a manufacturing system and the relationship between strategic goals and operational performance metrics. Two existing reference models related to manufacturing operations are represented formally and integrated to support the proposed method. The method is illustrated for a single scenario using agility as a strategic goal. By replicating the proposed method for other strategic goals and with multiple scenarios, a comprehensive set of performance challenges can be identified

Characterisation of heat transfer in high thermal conductivity graphite foam

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.This paper presents the results of an experimental investigation of forced convection heat transfer in microcellular graphite foam of high thermal conductivity. The test section was designed to be adiabatic with constant heat flux supplied at the bottom of the channel. The graphite foam heat sinks were fabricated into different structures and compared with conventional aluminum heat sinks of the same configurations. Heat transfer characteristics including local temperature and Nusselt number distributions for steady flow through the tested heat sinks were measured and discussed. The results show that graphite foam heat sinks give better heat transfer performance as compared to conventional aluminum heat sinks for different configurations. The highest heat transfer rate is obtained by the graphite foam heat sink with a fin structure. The study implies that graphite foam material can offer a combination of properties ideally suited for applications in high heat flux thermal management applications where conventional materials and products are not adequate.cs201

Mapping Strategic Goals and Operational Performance Metrics for Smart Manufacturing Systems

The complexity of the relationship of strategic goals to operational performance across the many levels of a manufacturing system inhibits the realization of Smart Manufacturing Systems (SMS). This paper proposes a method for identifying what aspects of a manufacturing system should be addressed to respond to changing strategic goals. The method uses standard techniques in specifying a manufacturing system and the relationship between strategic goals and operational performance metrics. Two existing reference models related to manufacturing operations are represented formally and integrated to support the proposed method. The method is illustrated for a single scenario using agility as a strategic goal. By replicating the proposed method for other strategic goals and with multiple scenarios, a comprehensive set of performance challenges can be identified. (C) 2015 The Authors. Published by Elsevier B.V.111215Ysciescopu

MICROFRACTURE OF HUMAN THORACOLUMBAR VERTEBRAL BODY UNDER FATIGUE LOADING

The purpose of this study was to investigate the relationship between lumbar vertebral microfracture and fatigue loading on young human spine under physiological cyclic compression loads. Thirty-three thoracolumbar vertebrae (T12 to L4) were obtained from 7 adult Chinese male cadavers. They were randomly divided into 5 groups. Cyclical compression was performed for 20,000 cycles with 2 Hz. Load magnitude was determined respectively as 10%, 20% and 30% of the ultimate compressive load. Four cylindrical sections were obtained from each vertebra and the cross-sectional slides were made. The histomorphometry was used to determine microfracture densitiy and distribution. No fracture was detected in the radiographs of groups III, IV and V after fatigue load. Microfracture density in the cyclic compression group increased from 0.46 #/mm2 in Group III to 0.66 #/mm2 (Group IV) and 0.94 #/mm2 (Group V) under different loading levels (). These results provide evidence for the existence of microfractures caused by fatigue loads that are undetectable by X-ray

The management of upper respiratory tract infections

Upper respiratory tract infections are the commonest reason for consultation in primary care. Group A β-haemolytic Streptococcus (GABHS), the most important bacterial pathogen in this condition, can be cultured from about 300 of patients, more so in children than adults. Clinical features that are predictive of positive GABHS culture are absence of cough, fever, cervical adenopathy, tonsillar enlargement and tonsillar exudate. Use of a sore throat score can help in the detection of streptococcal throat infection. Symptomatic therapies which are useful include anticholinergic, antihistamine, decongestant, humified hot air and Vitamin C. Antibiotics are universally over-prescribed in this condition as a result of high patient expectation and faulty clinical decision making. Oral Penicillin V for 10 days is the drug of choice. Effective intervention to reduce inappropriate antibiotic prescription probably require a multi-faceted approach targeted at both the patients and the prescribers

Integrating sequence and array data to create an improved 1000 Genomes Project haplotype reference panel

A major use of the 1000 Genomes Project (1000GP) data is genotype imputation in genome-wide association studies (GWAS). Here we develop a method to estimate haplotypes from low-coverage sequencing data that can take advantage of single-nucleotide polymorphism (SNP) microarray genotypes on the same samples. First the SNP array data are phased to build a backbone (or 'scaffold') of haplotypes across each chromosome. We then phase the sequence data 'onto' this haplotype scaffold. This approach can take advantage of relatedness between sequenced and non-sequenced samples to improve accuracy. We use this method to create a new 1000GP haplotype reference set for use by the human genetic community. Using a set of validation genotypes at SNP and bi-allelic indels we show that these haplotypes have lower genotype discordance and improved imputation performance into downstream GWAS samples, especially at low-frequency variants. © 2014 Macmillan Publishers Limited. All rights reserved

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society