Metal Matrix Composites as Potential Armour Materials

To defeat a kinetic energy projectile the armour needs to be extremely hard on the surface, so as to blunt the projectile on initial impact. A ceramic material may be an ideal choice. However, to absorb and dissipate the complete kinetic energy of the projectile, the subsequent material has to be extremely tough with a very high work of fracture. It also needs to be a light weight material to keep the overall weight to a minimum possible value. A fibre reinforced polymer matrix composite can meet the requirement. The innermost laver needs to have a very high ductility so as to avoid any fracture and fragment formation which could be lethal. So it has to be a metallic material. Thus, the application requires a range of properties starting from that of a ceramic and ending with that of a metal. Metal matrix composites (MMCs) are essentially metals reinforced with ceramic reinforcements, which exhibit a combination of properties of both the constituents and could be tailored to suit the requirements. Discontinuously reinforced MMCs also have the added advantage of being amenable to conventional metal forming operations, which makes it easier to produce them in the required shapes. This paper would provide an introduction to MMCs and review the available literature on their evaluation for possible applications as armour materials.It would also present the results of the preliminary studies on the dynamic hardness measurements of discontinuously reinforced aluminium alloy composites which gives a good indication of their potential use as armour materials

Ammonium sulfate crystallization in Andersen cascade impactor samples

Meteorologists are accustomed to the atmospheric phase changes of water. It is observed that phase changes ending with crystallization and crystal growth of (NH4)2SO4 take place in Andersen Samplers used to collect size-stratified samples of airborne particles. It is not at this point clear whether preformed (NH4)2SO4 crystals of small size are involved, although this is likely, but the cascade impaction processes evidently play a role in generating large (NH4)2SO4 crystals on the last few stages of these samplers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22246/1/0000682.pd

A Survey on Fog Computing: Services, Data and Security

Cloud computing can be used as a delivery platform which is a promising way for storing user data and provides a secure access to personal and business information. It involves prevention form risks like data theft and various other attacks. Cyber criminals can access the documents which can results in misuse of data and also interpretation of highly confidential data for illegal purposes. For securing user data from cyber attacks a new paradigm called fog computing can be used. This technique can monitor the user activity to identify the legitimacy and prevent from any unauthorised user access. Fog computing is a computing technique that extends cloud computing to the edge by providing Security in the cloud environment.. In fog computing , new security and privacy challenges are to be faced that are inherited from cloud computing. Mainly fog computing is used to reduce the burden on cloud by gathering workloads, services, applications and huge data to near network edge. In this paper we have discussed this paradigm for preventing misuse of user data and securing information, challenges and corresponding solutions in a brief manner

Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.

BACKGROUND:Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. METHODS AND RESULTS:Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P=0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [P=0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates. CONCLUSIONS:Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500

Evaporation and condensation of zinc

Evaporation rates of liquid zinc were determined experimentally within the temperature range of 450º C to 575º C and at argon pressures ranging from 730mm Hg to 130mm Hg. Extrapolated values of these rates are found to be consistent with the previously reported rates obtained by St. Clair and Spendlove at lower pressures. Between 100 microns and one atmosphere pressure rates of evaporation seem to vary according to an equation of the form W = APᴮ, where Pis pressure and, A and B are constants. Similar experiments were performed with brass powders in atmospheres of argon and helium at temperatures between 550º C and 650º C. The kinetics of sublimation of zinc from brass powders were found to be consistent with the evaporation behavior from a liquid zinc bath. The effect of various process conditions on the morphology of zinc condensed from the vapor phase was also determined --Abstract, page iii

Flame Emission Spectroscopy Using Uniform Sized Sample Droplets.

PhDAnalytical chemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/189851/2/7718038.pd

Errgrams – A Way to Improving ASR for Highly Inflected Dravidian Languages

In this paper, we present results of our experiments with ASR for a highly inflected Dravidian language, Telugu. First, we propose a new metric for evaluating ASR performance for inflectional languages (Inflectional Word Error Rate IWER) which takes into account whether the incorrectly recognized word corresponds to the same lexicon lemma or not. We also present results achieved by applying a novel method – errgrams – to ASR lattice. With respect to confidence scores, the method tries to learn typical error patterns, which are then used for lattice correction, and applied just before standard lattice rescoring. Our confidence measures are based on word posteriors and were improved by applying antimodels trained on anti-examples generated by the standard N-gram language model. For Telugu language, we decreased the WER from 45.2 % to 40.4 % (by 4.8 % absolute), and the IWER from 41.6 % to 39.5 % (2.1 % absolute), with respect to the baseline performance. All improvements are statistically significant using all three standard NIST significance tests for ASR.

Investigations into the neurophysiological basis of respiratory perception in humans using transient inspiratory occlusions

In humans breathing is an essential behaviour for life. It is recognized that humans and animals can perceive or sense their breathing, although the actual cortical and sub cortical structures by which this occurs remains unknown. The processing of sensations presumably arise from afferent information originating from mechanoreceptors within the muscles of the upper and lower airways, lungs and chest wall. This information is integrated by the central nervous system, which leads to a perception of respiratory sensations at th~ cortex, although the specific contnbutions of these sources remain unknown. In addition, distressing respiratory sensations such as breathlessness (dyspnoea) . and hyperinflation occur in individuals exhibiting pulmonary disease, such as asthma and chronic obstructive pulmonary disease (COPD). In response to these sensations, individuals can also voluntarily or behaviourally adjust their breathing. Hence, the aim of this thesis was to investigate: (i) the modulation of respiratory related sensory activity measured from the cortex in humans, using electroencephalography in response to applications of transient inspiratory occlusions (TIas) during hyperinflation, voluntary breathing and in tracheostomy patients' who lack an upper airway and (ii) the cortical and subcortical structures mediating the response to the TIO by using functional magnetic resonance imaging (fMRI). The results of these studies show that (i) voluntary breathing modulates respiratory perception, whereas perception is unaffected in tracheostomy patients and in hyperinflated states in response to TIas; and (ii) TIas can also generate cortical and sub cortical activity specifically activating sensory - motor structures including the, primary motor cortex, primary somatosensory cortex, supplementary motor area, inferior parietal areas, thalamus and cerebellum. In conclusion, respiratory perception (i) is altered by voluntary breathing; (ii) is unaffected .in hyperinflated and tracheostomized states; and (iii) can be investigated . using fMRl through the application of TIOs.EThOS - Electronic Theses Online ServiceGBUnited Kingdo