1,236 research outputs found

    Electromagnetic emission-aware schedulers for the uplink of OFDM wireless communication systems

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    The popularity and convergence of wireless communications have resulted in continuous network upgrades in order to support the increasing demand for bandwidth. However, given that wireless communication systems operate on radiofrequency waves, the health effects of electromagnetic emission from these systems are increasingly becoming a concern due to the ubiquity of mobile communication devices. In order to address these concerns, we propose two schemes (offline and online) for minimizing the EM emission of users in the uplink of OFDM systems, while maintaining an acceptable quality of service. We formulate our offline EM reduction scheme as a convex optimization problem and solve it through water-filling. This is based on the assumption that the long-term channel state information of all the users is known. Given that, in practice, long-term channel state information of all the users cannot always be available, we propose our online EM emission reduction scheme, which is based on minimizing the instantaneous transmit energy per bit of each user. Simulation results show that both our proposed schemes significantly minimize the EM emission when compared to the benchmark classic greedy spectral efficiency based scheme and an energy efficiency based scheme. Furthermore, our offline scheme proves to be very robust against channel prediction errors

    Study of hardness and tensile strength of Aluminium-7075 percentage varying reinforced with graphite and bagasse-ash composites

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    Waste sugarcane bagasse-ash and graphite utilizing as reinforcement in fabricating of an aluminium alloy (Al-7075) based matrix hybrid composites. The aluminium matrix hybrid composites have been fabricated by stir-casting method at 750 °C. Casting was developed in circular metal mould having 5 circular slots of diameter of 21 mm and length of 250 mm. Adding bagasse-ash with varying reinforcement of three cases, in first case 2% constant with varying graphite 1%, 3%, and 5%, in second case 4%, and in third case 6% constant with varying same graphite percentage. The effect of the reinforcement has been performed through various mechanical tests. The mechanical properties measuring such as Brinell hardness and tensile strength of both the samples have been prepared as per the ASTM E23 and E8 standards. Results give out that there will be greater effect of reinforcing different bagasse-ash in aluminium alloy matrix hybrid composites. In the third case more enhanced mechanical properties have been achieved as compared to case one and two of bagasse-ash combination. It shows that the selection of bagasse-ash as reinforcement has one of the most significant criteria for the fabrication of aluminium matrix hybrid composites

    Basal Cell Carcinomas in Gorlin Syndrome: A Review of 202 Patients

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    Gorlin syndrome (Naevoid Basal Cell Carcinoma Syndrome) is a rare autosomal dominant syndrome caused by mutations in the PTCH gene with a birth incidence of approximately 1 in 19,000. Patients develop multiple basal cell carcinomas of the skin frequently in early life and also have a predisposition to additional malignancies such as medulloblastoma. Gorlin Syndrome patients also have developmental defects such as bifid ribs and other complications such as jaw keratocysts. We studied the incidence and frequency of basal cell carcinomas in 202 Gorlin syndrome patients from 62 families and compared this to their gender and mutation type. Our data suggests that the incidence of basal cell carcinomas is equal between males and females and the mutation type cannot be used to predict disease burden

    A Review of Electricity Demand Forecasting in Low and Middle Income Countries: The Demand Determinants and Horizons

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    With the globally increasing electricity demand, its related uncertainties are on the rise as well. Therefore, a deeper insight of load forecasting techniques for projecting future electricity demands becomes imperative for business entities and policy makers. The electricity demand is governed by a set of different variables or “electricity demand determinants”. These demand determinants depend on forecasting horizons (long term, medium term, and short term), the load aggregation level, climate, and socio-economic activities. In this paper, a review of different electricity demand forecasting methodologies is provided in the context of a group of low and middle income countries. The article presents a comprehensive literature review by tabulating the different demand determinants used in different countries and forecasting the trends and techniques used in these countries. A comparative review of these forecasting methodologies over different time horizons reveals that the time series modeling approach has been extensively used while forecasting for long and medium terms. For short term forecasts, artificial intelligence-based techniques remain prevalent in the literature. Furthermore, a comparative analysis of the demand determinants in these countries indicates a frequent use of determinants like the population, GDP, weather, and load data over different time horizons. Following the analysis, potential research gaps are identified, and recommendations are provided, accordingly

    A UV-Spectrophotmetric Chemometric Method for the Simultaneous Determination of Sulfadoxine and Pyrimethamine in Tablets

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    In the present study, a simple, inexpensive, precise and accurate uv-spectrophotometric method based on chemometrics, has been developed for the simultaneous determination of sulfadoxine and pyrimethamine in tablet formulation. The % recoveries obtained were 99.7% ± 0.9 and 101.5% ± 0.8 for sulfadoxine and pyrimethamine, respectively. The developed method has been compared to USP-HPLC method with regard to accuracy and precision. The calculated F-ratio and the (t) statistics indicate that there is no significant difference at 5% level with regard to precision and accuracy between the proposed and the USP methods. Moreover, the developed method is simple, cost-effective, and less time-consuming. Accordingly, it can be used advantageously in routine quality control of sulfadoxine and pyrimethamine in tablet formulation

    Optimal Distribution of Renewable Energy Systems Considering Aging and Long-Term Weather Effect in Net-Zero Energy Building Design

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    Generation system interruptions in net-zero energy buildings (NZEBs) may result in missing the net-zero targets by a great margin. Consequently, it is significant to incorporate a realistic reliability model for renewable energy systems (RESs) that considers aging and long-term weather conditions. This study proposed a robust design optimization method that deals with the selection of RES to achieve NZEB. Different case studies were evaluated: 1. Deterministic approach; 2. Markov chain-based reliability without the aging effect; 3. Markov chain-based reliability with the aging effect. The results showed that the optimal sizes of RES, considering the aging effect, were much larger than the other two cases based on the annual energy balance. Moreover, the consideration of the aging effect on the reliability assessment of the generation system for NZEB opens a pathway for a more robust and economic design of RES

    Corneal nerves in health and disease

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    The cornea is the most sensitive structure in the human body. Corneal nerves adapt to maintain transparency and contribute to corneal health by mediating tear secretion and protective reflexes and provide trophic support to epithelial and stromal cells. The nerves destined for the cornea travel from the trigeminal ganglion in a complex and coordinated manner to terminate between and within corneal epithelial cells with which they are intricately integrated in a relationship of mutual support involving neurotrophins and neuromediators. The nerve terminals/receptors carry sensory impulses generated by mechanical, pain, cold and chemical stimuli. Modern imaging modalities have revealed a range of structural abnormalities such as attrition of nerves in neurotrophic keratopathy and post-penetrating keratoplasty; hyper-regeneration in keratoconus; decrease of sub-basal plexus with increased stromal nerves in bullous keratopathy and changes such as thickening, tortuosity, coiling and looping in a host of conditions including post corneal surgery. Functionally, symptoms of hyperaesthesia, pain, hypoaesthesia and anaesthesia dominate. Morphology and function do not always correlate. Symptoms can dominate in the absence of any visible nerve pathology and vice-versa. Sensory and trophic functions too can be dissociated with pre-ganglionic lesions causing sensory loss despite preservation of the sub-basal nerve plexus and minimal neurotrophic keratopathy. Structural and/or functional nerve anomalies can be induced by corneal pathology and conversely, nerve pathology can drive inflammation and corneal pathology. Improvements in accuracy of assessing sensory function and imaging nerves in vivo will reveal more information on the cause and effect relationship between corneal nerves and corneal diseases

    Conductive and inductive coupling between faulted power lines and buried pipeline by considering the effect of soil structure

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    The AC total interference of faulted power lines to gas pipelines sharing the same right of way, which may pose a threat to operating personnel and equipment, was studied. The main advantage of this work is to determine the effects of different soil structures on the induced voltage for various soil resistivities. Two main approaches were used to compute the induced voltages, namely the method of moment (MOM), which is based on electromagnetic field theory, and the circuit based method, which uses the circuit grounding analysis to compute the conductive interference and the circuit based models to compute the inductive interference. A 10-km-long parallel pipeline-transmission line model was developed. The soil resistivity was varied, and the induced voltages obtained from both approaches were compared. Soil resistivity and soil structure are important parameters that affect the AC interference level. The results of the study show that the earth potentials and the metal GPRS are independent. Higher soil resistivity causes the tower ground resistance to increase, thus making the shield wire’s attractiveness as a fault current return path to increase, which in turn forces the induced net EMF and the cumulative GPR in the pipeline to reduce

    Composite Multi-Criteria Decision Analysis for Optimization of Hybrid Renewable Energy Systems for Geopolitical Zones in Nigeria

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    This paper presents eight hybrid renewable energy (RE) systems that are derived from solar, wind and biomass, with energy storage, to meet the energy demands of an average household in the six geopolitical zones of Nigeria. The resource assessments show that the solar insolation, wind speed (at 30 m hub height) and biomass in the country range, respectively, from 4.38–6.00 kWh/m2/day, 3.74 to 11.04 m/s and 5.709–15.80 kg/household/day. The HOMER software was used to obtain optimal configurations of the eight hybrid energy systems along the six geopolitical zones’ RE resources. The eight optimal systems were further subjected to a multi-criteria decision making (MCDM) analysis, which considers technical, economic, environmental and socio-cultural criteria. The TOPSIS-AHP composite procedure was adopted for the MCDM analysis in order to have more realistic criteria weighting factors. In all the eight techno-economic optimal system configurations considered, the biomass generator-solar PV-battery energy system (GPBES) was the best system for all the geopolitical zones. The best system has the potential of capturing carbon from the atmosphere, an attribute that is desirous for climate change mitigation. The cost of energy (COE) was seen to be within the range of 0.151–0.156 US/kWh,whichiscompetitivewiththeexistingelectricitycostfromthenationalgrid,average0.131US/kWh, which is competitive with the existing electricity cost from the national grid, average 0.131 US/kWh. It is shown that the Federal Government of Nigeria favorable energy policy towards the adoption of biomass-to-electricity systems would make the proposed system very affordable to the rural households

    Effect of provision of home-based curative health services by public sector health-care providers on neonatal survival: a community-based cluster-randomised trial in rural Pakistan

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    Background Although the effectiveness of community mobilisation and promotive care delivered by community health workers in reducing perinatal and neonatal mortality is well established, evidence in support of home-based neonatal resuscitation and infection management is mixed. We assessed the effectiveness of adding training in neonatal bag and mask resuscitation and oral antibiotic therapy for suspected neonatal infections to a basic preventive and promotive interventions package delivered by public sector community-based lady health workers (LHWs) in rural Pakistan. Methods We did a cluster-randomised controlled trial in two subdistricts of Naushahro Feroze in rural Sindh, Pakistan, between April 15, 2009, and Dec 10, 2012. LHWs, trained in basic newborn resuscitation and in recognition and treatment (with oral amoxicillin) of suspected neonatal respiratory infections, were linked with traditional birth attendants and encouraged to attend home births. Control clusters received routine care through the existing national programme. The primary outcome was all-cause neonatal mortality. Independent data collection teams recorded data for all pregnancies and their outcomes, morbidity, mortality, and household practices related to maternal and newborn care. Findings Of the 27 randomised clusters with functional LHW programmes, 13 were allocated to the intervention group (n=242 749) and 14 to the control group (n=256 985). In the intervention group, LHWs did 80% of the planned community mobilisation sessions, but were able to attend only 1184 (14%) of 8425 deliveries and 4318 (25%) of 17 288 neonatal visits within 72 h of birth (p<0·0001 for both variables compared with the control group). The neonatal mortality rate was 42 deaths per 1000 livebirths in intervention clusters compared with 55 per 1000 in the control group (risk ratio 0·80, 95% CI 0·68–0·93; p=0·005). Interpretation The reduction in neonatal mortality in intervention clusters occurred against a background of improvements in domiciliary practices for maternal and newborn care. However, the poor reach of LHWs in accessing newborn infants at birth and in the early postnatal period underscores the limitations of tasking community health workers in public sector programmes working in similar circumstances with such complex interventions. Such community-based interventions in health systems should be accompanied by concerted efforts to improve quality of care in facilities and referral systems
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