Innovative Defense Technologies (United States)

Ambiguities in direction-of-arrival (DoA) estimation introduces significant challenges in wireless communication systems, particularly in applications requiring precise localization and sensing. These ambiguities can lead to misinterpretation of signal origins, severely impacting the performance and localization of systems such as Wireless Body Area Networks (WBANs) and Internet of Things (IoT) devices. In this paper, we investigate the ambiguities in an array of two symmetric conformal leaky-wave antenna (LWA) system, which, while offering enhanced field-of-view coverage, introduces complexities in resolving directional ambiguities. To address this issue, we propose a novel ambiguity resolution model based on a Long Short-Term Memory (LSTM) network. Our proposed LSTM-based approach achieves an accuracy of 99.99% in resolving ambiguities in comparison with other state of the art techniques. This advancement not only strengthens the reliability of conformal LWA systems but also lays the foundation for more robust and precise localization in wireless scenarios.

According to international statistics, nearly 50% of the world’s urban population live nowadays in cities of less than 500,000 inhabitants. These small and medium-sized cities play a role of intermediation between rural regions, local economy and more extensed urban networks, with three spheres of influence: micro-regional, national and international. In many of these “intermediate cities”, the main problem to reinforce them in their action is a lack of financial and human resources for managing the city in a comprehensive way, in order to tackle the demographic and spatial extension of these urban settlements, and avoid an increase of social segregation and fragmentation of territory. The example of Montes Claros, in the State of Minas Gerais, Brazil, helps us understand how a city of nearly 400,000 inhabitants, at the center of an economically prosperous region, tackles these issues through a current process of urban planning, having to take into account its historical, social and spatial context. Like most Brazilian and Latin American cities, Montes Claros-which acts as a transit hub at the State and national levels-is a rapidly growing intermediary city that has seen continued economic growth over the past two decades. However, this industrial and business growth has not resulted in a more inclusive distribution of the urban population. Considering the resulting growth from rural migration and new urban residents, the urban area of Montes Claros remains fragmented territorially, with neighborhoods more or less well equipped and served by public transport depending on the socio-economic status of their inhabitants. The current process of urban planning raises many issues, among them three crucial elements to improve in order to re-introduce planning as appropriate approach and instruments able to guide the decision makers towards the future of a city and its region: a medium and long-term vision for Montes Claros, its hinterland and the Northern region of Minas Gerais; a biased perception of Montes Claros in which only the dense areas in the city center are taken into account, with suburban areas still disconnected from the rest of the city and poorly integrated; a participatory process of urban planning involving all stakeholder and population, from the diagnostic till the definition of priorities in terms of urban policies, strategies and investments.

Bisphenol A (BPA) is a high production volume chemical intermediate used primarily in the production of polycarbonate plastics and epoxy resins. It primarily enters surface water and sediment via effluent discharges during its manufacture and use. The physical properties of BPA suggest that sediment is a potential sink and may result in exposure to benthic organisms. Currently there are no studies measuring the chronic toxicity of BPA to benthic organisms via direct sediment exposure. The present study examined the chronic toxicity of BPA to 3 commonly used test organisms that are generally representative of invertebrates occupying the base of the benthic food web and for which standardized testing protocols are available: the oligochaete Lumbriculus variegatus (mean numbers and biomass), the midge Chironomus riparius (emergence and development rate), and the estuarine amphipod Leptocheirus plumulosus (survival, growth, and reproduction). No-observed-effect concentrations (NOECs) for the 3 species ranged from 12 mg/kg to 54 mg/kg dry weight. All NOEC values were higher than all measured concentrations of BPA in freshwater and marine sediments reported in reliable, fully reported studies from North America and Europe from the 1990s to the present. For the first time, there are studies with BPA measuring the chronic toxicity to 3 taxa of sediment dwelling invertebrates, which are suitable to support region-specific risk assessments.

ABSTRACT The most commonly detected environmental metabolites of nonylphenol ethoxylates (NPE) are nonylphenol monoethoxylate (NPE1), nonylphenol diethoxylate (NPE2), nonylphenol ether carboxylates (NPEC), and nonylphenol (NP). Since NPEC have relatively low toxicity, the most relevant NPE metabolites for conducting an aggregate hazard assessment are NP, NPE1, and NPE2. Recent studies support the validity of the U.S. Environmental Protection Agency (2005) chronic water quality criteria (WQC) for NP in freshwater and saltwater environments; thus, these criteria were used as reference values in the aggregate hazard assessment. The toxic equivalency approach was used to assess the aggregate hazard of NP, NPE1, and NPE2. A review of relevant studies indicated that the toxic equivalency factor (TEF) for NPE1 and NPE2 approximated 0.37, which supported the use of the more conservative TEF value of 0.50 used by Environment Canada (2001) for NPE1 and NPE2. The interaction of toxicities between NP, NPE1, and NPE2 is assumed to be additive based on a review of the current literature and the shared mechanism of action of these compounds. The data support previous findings that there is a low likelihood that aggregate NP-equivalent concentrations of NPE and its metabolites in U.S. waters will exceed the national chronic WQC for NP.