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Abstract This paper investigates the performance of a variable ratio gearbox (VRG) used in a small fixed-speed wind turbine with active blades. The major components of the VRG-enabled drivetrain are an automatic-manual gearbox and squirrel cage induction generator that connects directly to the grid. The simplicity of this system may be appealing for applications when cost and reliability are of concern. It is an alternative to variable speed systems, which necessitate a modified generator and power conditioning equipment. During partial load operation the VRG provides a discrete set of rotor speeds. This allows the controller to track the wind speed and to achieve a greater efficiency. This study suggests three VRG ratios are sufficient to improve performance when used with active blades. A case study is presented where the performance is simulated using three different wind data sets. The study suggests that the VRG can improve production between 7 and 8.5% in low wind areas. The design procedure also illustrates a technique for finding the lowest and highest gear ratios needed for VRG design. These ratios allow the system to achieve the lowest cut-in and rated speeds. The approach also has useful implications for the design of a continuously variable transmission.

1. The gastroprotective activity of two azomethine prodrugs of (R)-alpha-methylhistamine was examined in lesions induced by absolute ethanol (1 ml/rat intragastrically for 1 h). 2. Pretreatment with (R)-alpha-methylhistamine as well as with the prodrugs (30 and 100 mg/kg intragastrically [IG]) significantly reduced macroscopically visible lesions caused by ethanol, with protection being almost complete at 100 mg/kg. 3. Histologically, in rats pretreated with the three compounds at a dose of 100 mg/kg, the evidence of damage was rare, with the appearance of gastric mucosa being similar in the different groups. 4. Present results are suggestive of a local component in the protective activity of (R)-alpha-methylhistamine.

Consumer interest in food products, including fresh vegetables, with health promoting properties is rising. In fresh vegetables, these properties include vitamins, minerals, dietary fiber, and secondary compounds, which collectively impart a large portion of the dietary, nutritional or health value associated with vegetable intake. Many, including farmers, aim to increase the health-promoting properties of fresh vegetables on the whole but they face at least three obstacles. First, describing crop composition in terms of its nutrition-based impact on human health is complex and there are few, if any, accepted processes and associated metrics for assessing and managing vegetable composition on-farm, at the origin of supply. Second, data suggest that primary and secondary metabolism can be 'in conflict' when establishing the abundance versus composition of a crop. Third, fresh vegetable farmers are rarely compensated for the phytochemical composition of their product. The development and implementation of a fresh vegetable 'nutritional yield' index could be instrumental in overcoming these obstacles. Nutritional yield is a function of crop biomass and tissue levels of health-related metabolites, including bioavailable antioxidant potential. Data from a multi-factor study of leaf lettuce primary and secondary metabolism and the literature suggest that antioxidant yield is sensitive to genetic and environmental production factors, and that changes in crop production and valuation will be required for fresh vegetable production systems to become more focused and purposeful instruments of public health.

Abstract For 118 million residential housing units in the U.S., there is currently a gap between the potential energy savings that can be achieved through the use of existing energy efficiency technologies, and the actual level of energy savings realized, particularly for the 37% of housing units that are considered residential rental properties. Additional quantifiable benefits are needed beyond energy savings to help further motivate residential property owners to invest in energy efficiency upgrades. This research focuses on assessing the adoption of energy efficient upgrades in U.S. residential housing and the impact on rental prices. Ten U.S. cities are chosen for analysis; these cities vary in size across multiple climate zones, and represent a diverse set of housing market conditions. Data was collected for over 159,000 rental property listings, their characteristics, and their energy efficiency measures listed in rental housing postings across each city. Following an extensive data quality control process, over thirty different types energy efficient features were identified. The level of adoption was determined for each city, ranging from 5.3% to 21.6%. Efficient lighting and appliances were among the most common, with many features doubling as energy efficient and other desirable aesthetic or comfort improvements. Then using propensity score matching and conditional mean comparison methods, the relative impact on rent charged in each city was calculated, which ranged from a 6% to 14.1% increase in rent for properties with energy efficient features, demonstrating a positive economic impact of these features, particularly for property owners. This was further subdivided into five types of energy efficiency upgrade and three housing types. Single family homes generally demanded higher premiums with energy efficient features, however there was not a consistent pattern across the types of efficient upgrades. The results of this work demonstrate that investment in energy efficient technologies has quantifiable benefits for rental property owners in the U.S. beyond just energy savings. This methodology and results can also be used in other cities and by property owners, utility companies, or others, ultimately encouraging further investment and positive economic impact in residential energy efficiency and in turn improving energy and resource conservation in the building sector.

Abstract This review article places in perspective the new work devoted both to the analysis of the thermodynamic irreversibility of heat and mass transfer components and systems and to the design of these devices on the basis of entropy generation minimization. The review focuses on the fundamental mechanisms responsible for the generation of entropy in heat and fluid flow and on the design tradeoff of balancing the heat transfer irreversibility against the fluid flow irreversibility. Applications are selected from the fields of heat exchanger design, thermal energy storage, and mass exchanger design. This article provides a comprehensive, up-to-date review of second-daw analyses published in the heat and mass transfer literature during the last decade.

Abstract Large-scale cultivation of microalgal biomass in open systems can benefit from the low cost of using natural sunlight, as opposed to artificial light, but may encounter problems with photoinhibition, high evaporation rates, potential contamination and high energy demand. Wavelength selective luminescent solar concentrator (LSC) panels can solve some of these problems when incorporated into low-cost sheltered structures for algal biomass production that concurrently produce their own electricity by harnessing select portions of solar energy, not used for algal growth. The LSC panels in this study contained a fluorescent dye, Lumogen Red 305, which transmits blue and red wavelengths used for photosynthesis with high efficiency, while absorbing the green wavelengths and re-emitting them as red wavelengths. The fluorescently generated red wavelengths are either transmitted to boost algal growth, or waveguided and captured by photovoltaic cells to be converted into electricity. We found that different strains of microalgae (currently used commercially) grew equally well under the altered spectral conditions created by the luminescent panels, compared to growth under the full solar spectrum. Thus this technology presents a new approach wherein algae can be grown under protected, controlled conditions, while the cost of operations is offset by the structure's internal electrical production, without any loss to algal growth rate or achievable biomass density.

An experimental study on the flow and heat transfer in open vertical enclosures, representing elevator shafts, warehouses, and atriums, due to a building fire is carried out, using a scale model. Smoke and hot gases are injected into the enclosure at a lower opening and the resulting downstream flow and temperature fields are studied. The inlet temperature and flow rate of the hot gases are varied over wide ranges to simulate the flow due to fire in multi-leveled buildings with vertical open shafts or atriums under natural ventilation. The conditions at the outlet, which is located on the same wall as the inlet, are also monitored to determine the effects of entrainment into the flow and heat transfer to the walls. Typical values of the operating conditions have been investigated, ranging from high buoyancy levels, for which the flow stays close to the vertical wall of the enclosure, to much lower levels, at which the flow enters the enclosure with a significant flow velocity and spreads outward very quickly. With increasing temperature at the inlet, the buoyancy effect is larger, resulting in higher velocities and shorter time to reach the top. The measured temperature at the outlet depends on heat transfer to the walls as well as on the flow velocity. Detailed measurements of the velocity and temperature fields have also been taken. It is found that a wall plume is generated which conveys the hot fluid rapidly along the vertical wall containing the inlet and the outlet. A recirculating flow arises away from this wall and this flow affects the heat transfer and flow in the wall plume. This feature, in turn, affects the entrainment into the flow, decay of the temperature level and the evolution of mean flow. Therefore, horizontally uniform conditions cannot be assumed here, as employed in several studies of tall enclosures. The wall plume has to be modeled in this case, considering the entrainment into the boundary layer flow and the effect of the recirculating flow.

Low-salinity water injection emerges to be a cost-effective and environmentally friendly enhanced oil recovery technique. Furthermore, additives, such as the surfactant and nanoparticles in combina...