578 research outputs found

    Body-freedom flutter of a 1/2-scale forward-swept-wing model, an experimental and analytical study

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    The aeroelastic phenomenon known as body-freedom flutter (BFF), a dynamic instability involving aircraft-pitch and wing-bending motions which, though rarely experienced on conventional vehicles, is characteristic of forward swept wing (FSW) aircraft was investigated. Testing was conducted in the Langley transonic dynamics tunnel on a flying, cable-mounted, 1/2-scale model of a FSW configuration with and without relaxed static stability (RSS). The BFF instability boundaries were found to occur at significantly lower airspeeds than those associated with aeroelastic wing divergence on the same model. For those cases with RSS, a canard-based stability augmentation system (SAS) was incorporated in the model. This SAS was designed using aerodynamic data measured during a preliminary tunnel test in which the model was attached to a force balance. Data from the subsequent flutter test indicated that BFF speed was not dependent on open-loop static margin but, rather, on the equivalent closed-loop dynamics provided by the SAS. Servo-aeroelastic stability analyses of the flying model were performed using a computer code known as SEAL and predicted the onset of BFF reasonably well

    The role of human milk oligosaccharides and probiotics on the neonatal microbiome and risk of necrotizing enterocolitis: A narrative review

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    Preterm infants are a vulnerable population at risk of intestinal dysbiosis. The newborn microbiome is dominated b

    Experimental evaluation of NFC reliability between an RFID tag and a smartphone

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    Abstract:Near Field Communication (NFC) is a short range wireless technology that enables data transfer between two NFC devices. It is derived from Radio Frequency Identification (RFID) technology. However, NFC only operates at 13.56MHz frequency while RFID operates at both 125KHz and 13.56MHz frequencies. The success of NFC in replacing contact cards in payment systems can be duplicated in other industries. It is very critical that the operation of NFC is well understood so that future applications can make life easier for the users. The main purpose of this paper is to find out the parameters that can affect the optimal operation of passive NFC devices

    Wireless sensor networks and advanced metering infrastructure deployment in smart grid

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    The increasing demand for has necessitated the introduction of information and communication technologies (ICT) in the development of the smart grid. Advanced Metering Infrastructure (AMI) and Wireless Sensor Networks (WSNs) are contributing technologies. In this paper, a review on AMI and WSN in the smart grid is carried out. Also, the introduction of WSNs with AMI in the in-home energy management system of the smart grid is also presented with challenges faced in the deployment of WSNs for the smart grid. The low power and low-cost nature of WSN has presented itself as a technology that can be used with AMI and smart home appliances in achieving home energy management within the great goal of the smart grid

    Time programmable smart devices for peak demand reduction of smart homes in a microgrid

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    Abstract: Increasing electricity access through Microgrids for rural areas is often faced with the challenge of increased peak demand through increased electricity demand as more electronic devices will be acquired by the consumers and more small businesses will spring up in the community. If not taken care of, this leads to additional cost of incurring higher peaker plants to meet the peak demand, and the burden of the cost of peaker plants are consequentially transferred to the consumers. Since this load is generated by the consumers, it is most desirable to control the peak demand from the consumers’ side. Therefore, a method of Time Programmable Smart Devices (TPSD) with an efficient Electricity Use Plan (EUP) is proposed in this paper by introducing appliance working knowledge and improving load shifting technique of Demand Side Management for peak demand reduction in a rural Microgrid. This method yielded lower morning and evening peaks, a lower peak-to-peak difference than those available in literature, and a peak period shift from the traditional peak period to traditional off-peak period. These lead to financial savings, reduced cost of peaker plants and a safer environment from less greenhouse gases emissions

    Effective energy consumption scheduling in smart homes

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    Abstract: Monthly expenditure on electricity by most households in South Africa take beyond acceptable percentage of their income. In order to keep the household energy expenditure below the energy poverty threshold, a daily electricity optimization problem is formulated using mixed integer linear programming (MILP) method. The energy optimization scheduling was carried out by a device called the Daily Maximum Energy Scheduling (DMES) device proposed to be incorporated into smart meters of households. The DMES algorithm was tested with household data set and was shown to be capable of ensuring that households spend less than 10% of their income on electricity bill monthly. This technique therefore, would be beneficial to consumers (for better financial savings and planning), utility (for effective energy and financial savings, and energy network planning) and cleaner environments as proposed for smart grid. Also, number of households in the nation living below the energy expenditure-based poverty threshold would increase

    The Papers of Thomas A. Edison

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    This richly illustrated volume explores Edison’s inventive and personal pursuits from 1885 to 1887.Two decades after the American Civil War, no name was more closely associated with the nation’s inventive and entrepreneurial spirit than that of Thomas Edison. The restless changes of those years were reflected in the life of America’s foremost inventor. Having cemented his reputation with his electric lighting system, Edison had decided to withdraw partially from that field. At the start of 1885, newly widowed at mid-life with three young children, he launched into a series of personal and professional migrations, setting in motion chains of events that would influence his work and fundamentally reshape his life. Edison’s inventive activities took off in new directions, flowing between practical projects (such as wireless and high-capacity telegraph systems) and futuristic ones (exploring forms of electromagnetic energy and the convertibility of one to another). Inside of two years, he would travel widely, marry the daughter of a prominent industrialist and religious educator, leave New York City for a grand home in a sylvan suburb, and construct a winter laboratory and second home in Florida. Edison’s family and interior life are remarkably visible at this moment; his papers include the only known diary in which he recorded personal thoughts and events. By 1887, the familiar rhythms of his life began to reassert themselves in his new settings; the family faded from view as he planned, built, and occupied a New Jersey laboratory complex befitting his status. The eighth volume of the series, New Beginnings includes 358 documents (chosen from among thousands) that are the most revealing and representative of Edison’s work, life, and place in American culture in these years. Illustrated with hundreds of Edison’s drawings, these documents are further illuminated by meticulous research on a wide range of sources, including the most recently digitized newspapers and journals of the day

    Summer Peaks in Uptake of Human Papillomavirus and Other Adolescent Vaccines in the United States

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    BACKGROUND: Seasonality in human papillomavirus (HPV) vaccination could have a large impact on national cancer prevention efforts. We hypothesized that uptake of HPV vaccine and other adolescent vaccines in the United States would be highest in the summer. METHODS: Data came from health care provider-verified vaccination records for 70,144 adolescents (ages 13-17 years) from the 2008 to 2012 versions of the National Immunization Survey-Teen. Using the Edwards method for testing annual trends, we examined seasonal patterns in the uptake of HPV and other recommended adolescent vaccines [tetanus, diphtheria, and pertussis (Tdap) booster and meningococcal vaccine]. HPV vaccine initiation (receipt of the first of the three-dose series) data were for female adolescents. RESULTS: Uptake for HPV and other adolescent vaccines peaked in the summer across years and states (all P < 0.001). Uptake was five times as frequent at the peak as at the trough for HPV vaccine, and HPV vaccine initiation was highest in June, July, and August (percent of doses delivered in these months: 38.7%). The same pattern existed for Tdap booster and meningococcal vaccine. Concomitant (same-day) vaccination of HPV vaccine with other adolescent vaccines also demonstrated summer peaks each year nationally (all P < 0.001). CONCLUSION: Uptake of adolescent vaccines increased dramatically in summer months. These summer peaks are an important opportunity for interventions focused on concomitant vaccination. IMPACT: The potential cancer prevention impact of HPV vaccination programs could be increased, for example, by delivering messages about concomitant vaccination during the summer, when adolescents and their parents might be most open to them

    Mobile sink wireless underground sensor communication monitor

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    Mine disasters claim thousands of human lives and cause millions of property loss every year. The safety of the mine worker is of paramount importance in any underground environment. Advances in the development of Wireless Sensor Networks (WSNs) for monitoring infrastructure health, and environmental conditions provide end users with the benefit of low-cost installation, maintenance and scalability. This paper will investigate the challenges around a development of a real-time mine monitoring system using wireless sensor nodes to prevent mine disasters such as gas explosions or mine collapses. We propose a mobile, real-time gateway that will be able to process data collected from static wireless sensor nodes monitoring underground infrastructure, to prevent underground disasters
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