Riblets for aircraft skin-friction reduction

Energy conservation and aerodynamic efficiency are the driving forces behind research into methods to reduce turbulent skin friction drag on aircraft fuselages. Fuselage skin friction reductions as small as 10 percent provide the potential for a 250 million dollar per year fuel savings for the commercial airline fleet. One passive drag reduction concept which is relatively simple to implement and retrofit is that of longitudinally grooved surfaces aligned with the stream velocity. These grooves (riblets) have heights and spacings on the order of the turbulent wall streak and burst dimensions. The riblet performance (8 percent net drag reduction thus far), sensitivity to operational/application considerations such as yaw and Reynolds number variation, an alternative fabrication technique, results of extensive parametric experiments for geometrical optimization, and flight test applications are summarized

Combined riblet and lebu drag reduction system

The invention is a system of flow control devices which result in reduced skin friction on aerodynamic and hydrodynamic surfaces. The devices cause a breakup of large-scale disturbances in the boundary layer of the flow field. The riblet device acts to reduce disturbances near the boundary layer wall by the use of longitudinal striations forming V-shaped grooves. These grooves are dimensional on the order of the wall vortices and turbulent burst dimensions. The large eddy breakup device is a small strip or airfoil which is suspended in the upper region of the boundary layer. Various physical mechanisms cause a disruption of the large-scale vortices. The combination of the devices of this invention result in a substantial reduction in skin friction drag

Carbon Free Boston: Waste Technical Report

Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Technical Summary; Carbon Free Boston: Buildings Technical Report; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Energy Technical Report; Carbon Free Boston: Offsets Technical Report; Available at http://sites.bu.edu/cfb/OVERVIEW: For many people, their most perceptible interaction with their environmental footprint is through the waste that they generate. On a daily basis people have numerous opportunities to decide whether to recycle, compost or throwaway. In many cases, such options may not be present or apparent. Even when such options are available, many lack the knowledge of how to correctly dispose of their waste, leading to contamination of valuable recycling or compost streams. Once collected, people give little thought to how their waste is treated. For Boston’s waste, plastic in the disposal stream acts becomes a fossil fuel used to generate electricity. Organics in the waste stream have the potential to be used to generate valuable renewable energy, while metals and electronics can be recycled to offset virgin materials. However, challenges in global recycling markets are burdening municipalities, which are experiencing higher costs to maintain their recycling. The disposal of solid waste and wastewater both account for a large and visible anthropogenic impact on human health and the environment. In terms of climate change, landfilling of solid waste and wastewater treatment generated emissions of 131.5 Mt CO2e in 2016 or about two percent of total United States GHG emissions that year. The combustion of solid waste contributed an additional 11.0 Mt CO2e, over half of which (5.9 Mt CO2e) is attributable to the combustion of plastic [1]. In Massachusetts, the GHG emissions from landfills (0.4 Mt CO2e), waste combustion (1.2 Mt CO2e), and wastewater (0.5 Mt CO2e) accounted for about 2.7 percent of the state’s gross GHG emissions in 2014 [2]. The City of Boston has begun exploring pathways to Zero Waste, a goal that seeks to systematically redesign our waste management system that can simultaneously lead to a drastic reduction in emissions from waste. The easiest way to achieve zero waste is to not generate it in the first place. This can start at the source with the decision whether or not to consume a product. This is the intent behind banning disposable items such as plastic bags that have more sustainable substitutes. When consumption occurs, products must be designed in such a way that their lifecycle impacts and waste footprint are considered. This includes making durable products, limiting the use of packaging or using organic packaging materials, taking back goods at the end of their life, and designing products to ensure compatibility with recycling systems. When reducing waste is unavoidable, efforts to increase recycling and organics diversion becomes essential for achieving zero waste. [TRUNCATED]Published versio

Carbon Free Boston: Offsets Technical Report

Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Technical Summary; Carbon Free Boston: Buildings Technical Report; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Waste Technical Report; Carbon Free Boston: Energy Technical Report; Available at http://sites.bu.edu/cfb/OVERVIEW: The U.S. Environmental Protection Agency defines offsets as a specific activity or set of activities intended to reduce GHG emissions, increase the storage of carbon, or enhance GHG removals from the atmosphere [1]. From a city perspective, they provide a mechanism to negate residual GHG emissions— those the city is unable to reduce directly—by supporting projects that avoid or sequester them outside of the city’s reporting boundary. Offsetting GHG emissions is a controversial topic for cities, as the co-benefits of the investment are typically not realized locally. For this reason, offsetting emissions is considered a last resort, a strategy option available when the city has exhausted all others. However, offsets are likely to be a necessity to achieve carbon neutrality by 2050 and promote emissions reductions in the near term. While public and private sector partners pursue the more complex systems transformation, cities can utilize offsets to support short-term and relatively cost-effective reductions in emissions. Offsets can be a relatively simple, certain, and high-impact way to support the transition to a low-carbon world. This report focuses on carbon offset certificates, more often referred to as offsets. Each offset represents a metric ton of verified carbon dioxide (CO2) or equivalent emissions that is reduced, avoided, or permanently removed from the atmosphere (“sequestered”) through an action taken by the creator of the offset. The certificates can be traded and retiring (that is, not re-selling) offsets can be a useful component of an overall voluntary emissions reduction strategy, alongside activities to lower an organization’s direct and indirect emissions. In the Global Protocol for Community-Scale Greenhouse Gas Emissions Inventories (GPC), the GHG accounting system used by the City of Boston, any carbon offset certificates that the City has can be deducted from the City’s total GHG emissions.http://sites.bu.edu/cfb/files/2019/06/CFB_Offsets_Technical_Report_051619.pdfPublished versio

Carbon Free Boston: Energy Technical Report

Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Technical Summary; Carbon Free Boston: Buildings Technical Report; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Waste Technical Report; Carbon Free Boston: Offsets Technical Report; Available at http://sites.bu.edu/cfb/INTRODUCTION: The adoption of clean energy in Boston’s buildings and transportation systems will produce sweeping changes in the quantity and composition of the city’s demand for fuel and electricity. The demand for electricity is expected to increase by 2050, while the demand for petroleum-based liquid fuels and natural gas within the city is projected to decline significantly. The city must meet future energy demand with clean energy sources in order to meet its carbon mitigation targets. That clean energy must be procured in a way that supports the City’s goals for economic development, social equity, environmental sustainability, and overall quality of life. This chapter examines the strategies to accomplish these goals. Improved energy efficiency, district energy, and in-boundary generation of clean energy (rooftop PV) will reduce net electric power and natural gas demand substantially, but these measures will not eliminate the need for electricity and gas (or its replacement fuel) delivered into Boston. Broadly speaking, to achieve carbon neutrality by 2050, the city must therefore (1) reduce its use of fossil fuels to heat and cool buildings through cost-effective energy efficiency measures and electrification of building thermal services where feasible; and (2) over time, increase the amount of carbon-free electricity delivered to the city. Reducing energy demand though cost effective energy conservation measures will be necessary to reduce the challenges associated with expanding the electricity delivery system and sustainably sourcing renewable fuels.Published versio

Optimization methods applied to the aerodynamic design of helicopter rotor blades

Described is a formal optimization procedure for helicopter rotor blade design which minimizes hover horsepower while assuring satisfactory forward flight performance. The approach is to couple hover and forward flight analysis programs with a general-purpose optimization procedure. The resulting optimization system provides a systematic evaluation of the rotor blade design variables and their interaction, thus reducing the time and cost of designing advanced rotor blades. The paper discusses the basis for and details of the overall procedure, describes the generation of advanced blade designs for representative Army helicopters, and compares design and design effort with those from the conventional approach which is based on parametric studies and extensive cross-plots

An Evaluation of Growth Characteristics of Faba Bean Cultivars

Resistance to herbicides and the lack of new herbicide options have led researchers to explore alternate methods to manage weed populations in large-scale cropping systems. Crop competition is an effective weed management approach that can reduce the pressure on herbicides. Faba bean (Vicia faba L.) is an important winter legume crop in Australia. Crop traits such as, height, biomass, growth rate, tillering capacity, leaf area, and root growth have been suggested as indicators of the competitive ability of crops against weeds. Based on pot studies at Narrabri and Toowoomba, we assessed the growth traits (biomass, height, leaf area, relative growth rate, and branch number) of six faba bean cultivars and ranked them for their potential ability to compete with weeds. PBA Marne and PBA Zahra were identified as highly competitive faba bean cultivars based on their higher overall ranking score achieved at both locations. PBA Nasma and PBA Samira were ranked highly and moderately competitive at Narrabri and Toowoomba sites, respectively. At Narrabri, PBA Nanu was ranked poorly competitive based on its lower biomass, height, and leaf area than the other cultivars. The weed suppressive ability of these cultivars needs to be assessed in the presence of weeds under field conditions

Discrimination of Individual Tigers (\u3cem\u3ePanthera tigris\u3c/em\u3e) from Long Distance Roars

This paper investigates the extent of tiger (Panthera tigris) vocal individuality through both qualitative and quantitative approaches using long distance roars from six individual tigers at Omaha\u27s Henry Doorly Zoo in Omaha, NE. The framework for comparison across individuals includes statistical and discriminant function analysis across whole vocalization measures and statistical pattern classification using a hidden Markov model (HMM) with frame-based spectral features comprised of Greenwood frequency cepstral coefficients. Individual discrimination accuracy is evaluated as a function of spectral model complexity, represented by the number of mixtures in the underlying Gaussian mixture model (GMM), and temporal model complexity, represented by the number of sequential states in the HMM. Results indicate that the temporal pattern of the vocalization is the most significant factor in accurate discrimination. Overall baseline discrimination accuracy for this data set is about 70% using high level features without complex spectral or temporal models. Accuracy increases to about 80% when more complex spectral models (multiple mixture GMMs) are incorporated, and increases to a final accuracy of 90% when more detailed temporal models (10-state HMMs) are used. Classification accuracy is stable across a relatively wide range of configurations in terms of spectral and temporal model resolution

Superior Facial Expression, But Not Identity Recognition, in Mirror-Touch Synesthesia

Simulation models of expression recognition contend that to understand another's facial expressions, individuals map the perceived expression onto the same sensorimotor representations that are active during the experience of the perceived emotion. To investigate this view, the present study examines facial expression and identity recognition abilities in a rare group of participants who show facilitated sensorimotor simulation (mirror-touch synesthetes). Mirror-touch synesthetes experience touch on their own body when observing touch to another person. These experiences have been linked to heightened sensorimotor simulation in the shared-touch network (brain regions active during the passive observation and experience of touch). Mirror-touch synesthetes outperformed nonsynesthetic participants on measures of facial expression recognition, but not on control measures of face memory or facial identity perception. These findings imply a role for sensorimotor simulation processes in the recognition of facial affect, but not facial identity

Boston Climate Progress Report 2022

This report, to be updated every two years, examines Boston's progress toward achieving net-zero emissions by 2050, our resilience to future climate disruptions, and the equity of our climate response. It also highlights a dozen key outcomes that must be achieved by programs, projects, and initiatives whose success is imperative to reaching the overarching goals, and lays out four "big lifts," system-transforming actions which Boston—along with the broader region and state—needs to accelerate to sharply reduce net emissions