Split-Stirling-cycle displacer linear-electric drive

The retrofit of a 1/4-W split-Stirling cooler with a linear driven on the displacer was achieved and its performance characterized. The objective of this work was to demonstrate that a small linear motor could be designed to meet the existing envelope specifications of the cooler and that an electric linear drive on the displacer could improve the cooler's reliability and performance. The paper describes the characteristics of this motor and presents cooler test results

Launch window analysis of satellites in high eccentricity or large circular orbits

Numerical methods and computer programs for studying the stability and evolution of orbits of large eccentricity are presented. Methods for determining launch windows and target dates are developed. Mathematical models are prepared to analyze the characteristics of specific missions

Bacterial ‘Cell’ Phones: Do cell phones carry potential pathogens?

Cell phones are important companions for professionals especially health care workers (HCWs) for better communication in hospital. The present study compared the nature of the growth of potentially pathogenic bacterial flora on cell phones in hospital and community. 75% cell phones from both the categories grew at least one potentially pathogenic organism. Cell phones from HCWs grew significantly more potential pathogens like MRSA (20%), Acinetobacter species (5%), Pseudomonas species (2.5%) as compared to the non HCWs. 97.5% HCWs use their cell phone in the hospital, 57.5% never cleaned their cell phone and 20% admitted that they did not wash their hands before or after attending patients, although majority (77.5%) knows that cell phones can have harmful colonization and act as vector for nosocomial infections. It is recommended, therefore, that cell phones in the hospital should be regularly decontaminated. Moreover, utmost emphasis needs to be paid to hand washing practices among HCWs

VIBRATION ANALYSIS OF DRILLING OPERATION

Vibrations are produced during any machining process. For drilling operation, analysis of these vibrations plays an important role in order to predict phenomenon of ‘chatter’. This paper emphasizes the analysis of vibration during drilling operation. The output results of analysis are useful to find out amplitude of vibrations produced with respect to drill size and spindle speed for standard rate of recommended feed/min. Analysis is quantified and tabulated as per available machining parameters of ‘THAKUR PELTER DRILLING MACHINE’ which is present in the Workshop of Fr. Conceiceo Rodrigues Institute of Technology, Vashi, Navi Mumbai. The optimum values of spindle speed and feed for maximium amplitude of transverse vibrations with respect to drill size are highlighted in the table and brought to the notice of Workshop Superintendent. The table of formulated results is displayed near this drilling machine

Performance testing open source products for the TMT event service

The software system for TMT is a distributed system with many components on many computers. Each component integrates with the overall system using a set of software services. The Event Service is a publish-subscribe message system that allows the distribution of demands and other events. The performance requirements for the Event Service are demanding with a goal of over 60 thousand events/second. This service is critical to the success of the TMT software architecture; therefore, a project was started to survey the open source and commercial market for viable software products. A trade study led to the selection of five products for thorough testing using a specially constructed computer/network configuration and test suite. The best performing product was chosen as the basis of a prototype Event Service implementation. This paper describes the process and performance tests conducted by Persistent Systems that led to the selection of the product for the prototype Event Service

Are Twin Pregnancies Complicated by Weight Discordance or Fetal Growth Restriction at Higher Risk of Preeclampsia?

Studies have reported controversial findings on the association between fetal growth restriction (FGR) or intertwin weight discordance and the risk of hypertensive disorders of pregnancy (HDP) in twin pregnancies. The aim of this study was to investigate the association between twin growth disorders and HDP. Twin pregnancies resulting in two live births at St George's Hospital between 2000 and 2019 were included. FGR or small-for-gestational-age (SGA) at birth was assessed using singleton and twin reference charts. Intertwin discordance [(large birthweight - small birthweight)/(large birthweight) × 100%)] was calculated. Logistic regression models were performed. SGA (aOR 2.34, 95% CI 1.60-3.44, p < 0.001), intertwin discordance ≥25% (aOR 2.10, 95% CI 1.26-3.49, p = 0.004) and their co-existence (aOR 2.03, 95% CI 1.16-3.54, p = 0.013) were significantly associated with HDP. After adjusting for the known maternal risk factors of HDP and the intertwin discordance, SGA (using the twin charts) was the strongest independent risk factor associated with HDP (aOR 2.12, 95% CI 1.40-3.22, p < 0.001) and preeclampsia (aOR 2.34, 95% CI 1.45-3.76, p < 0.001). This study highlights that the presence of at least one SGA twin is significantly associated with HDP during pregnancy. Therefore, maternal blood pressure should be closely monitored in twin pregnancies complicated by SGA with or without intertwin discordance

Fracture in Mode I using a Conserved Phase-Field Model

We present a continuum phase-field model of crack propagation. It includes a phase-field that is proportional to the mass density and a displacement field that is governed by linear elastic theory. Generic macroscopic crack growth laws emerge naturally from this model. In contrast to classical continuum fracture mechanics simulations, our model avoids numerical front tracking. The added phase-field smoothes the sharp interface, enabling us to use equations of motion for the material (grounded in basic physical principles) rather than for the interface (which often are deduced from complicated theories or empirical observations). The interface dynamics thus emerges naturally. In this paper, we look at stationary solutions of the model, mode I fracture, and also discuss numerical issues. We find that the Griffith's threshold underestimates the critical value at which our system fractures due to long wavelength modes excited by the fracture process.Comment: 10 pages, 5 figures (eps). Added 2 figures and some text. Removed one section (and a figure). To be published in PR