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Modeling from the perspectives of software engineering and systems engineering have co-evolved over the last two decades as orthogonal approaches. Given the central role of software in modern cyber-physical systems and the increasing adoption of digital engineering practices in complex systems design, there is now significant opportunity for collaborative design among system users, software developers, and systems engineers. Model-based systems engineering (MBSE) and systems modeling languages can support seamless cross-domain connectivity for design, simulation, and analysis of emerging technologies such as Augmented Reality (AR). This paper presents a co-design process for extending the capability of an existing AR application referred to as a No-Code AR Systems (NCARS) framework. NCARS enables content developed by multi-domain authors to be deployed on AR devices through a software layer that bridges the content to the game engine that drives the AR system. Utilizing a software dependency diagram of the AR Annotation function, an existing MBSE model of the AR system is extended to include the structure and behavior of relevant software components. This allows a modular design of the system to address needs in integrating new requirements into the existing application. New user requirements for tracking items in motion in the user’s physical environment with virtual annotations in the augmented space are collaboratively designed and visualized through use case, block definition, internal block, and sequence diagrams. They capture the required structure and behavior of the proposed to-be system. 

Corrections for first-order particle losses to Teflon chamber walls are important sources of uncertainty in experimental studies of particle formation and aging. Particle size distributions and environmental factors significantly influence wall loss corrections; thus, it is important to characterize size-dependent particle loss profiles under myriad experimental conditions that may alter deposition rates. This work investigated size-dependent loss coefficients of inorganic (ammonium sulfate, AS), organic (sorbitol, C6H14O6), and mixed composition (AS + sorbitol, 1:1 by mole) particles to a Teflon chamber under varying chamber temperature (20–40 °C), relative humidity (RH, <10–80%), illumination (dark vs. 100% chamber lights), particle water (crystalline vs. deliquesced vs. metastable), and chamber usage history conditions (clean chamber vs. following chemical experiments). It was found that temperature and lights had negligible to minor effects on loss rates for all particles, while RH, particle water, and chamber usage history each had major effects under all tested conditions. Particle wall loss rates were higher under humid than dry conditions, and higher for deliquesced particles than for dry particles at similar RH. Chemical conditions that introduced acidic species to chamber walls the day prior to a wall loss experiment were responsible for uncertainties of up to ∼50% in wall loss rate profiles, despite recommended chamber flushing regimens. These data suggest that sensitive OA formation or aging experiments may consider obtaining same-day wall loss profiles from the target experiment. Otherwise, size-dependent corrections for particle wall loss should consider particle composition, particle water, RH, wall usage history, and possibly illumination conditions. 

Atmospheric chemistry models generally assume organic aerosol (OA) to be photochemically inert. Recent mechanisms for the oxidation of biogenic isoprene, a major source of secondary organic aerosol (iSOA), produce excessive OA in the absence of subsequent OA reactivity. At the same time, models underestimate atmospheric concentrations of formic and acetic acids for which OA degradation could provide a source. Here we show that the aqueous photooxidation of an isoprene-derived organosulfate (2-methyltriolsulfate or MTS), an important iSOA component, produces formic and acetic acids in high yields and at timescales competitive with deposition. Experimental data are well fit by a kinetic model in which three sequential oxidation reactions of the isoprene organosulfate produce two molar equivalents of formic acid and one of acetic acid. We incorporate this chemistry and that of 2-methyltetrol, another ubiquitous iSOA component, into the GEOS-Chem global atmospheric chemistry model. Simulations show that photooxidation and subsequent revolatilization of this iSOA may account for up to half of total iSOA loss globally, producing 4 Tg a−1 each of formic and acetic acids. This reduces model biases in gas-phase formic acid and total organic aerosol over the Southeast United States in summer by ∼30% and 60% respectively. While our study shows the importance of adding iSOA photochemical sinks into atmospheric models, uncertainties remain that warrant further study. In particular, improved understanding of reaction dependencies on particle characteristics and concentrations of particle-phase OH and other oxidants are needed to better simulate the effects of this chemistry on the atmospheric budgets of organic acids and iSOA. 

Augmented Reality (AR) devices offer novel capabilities that can be exploited in AR systems to positively impact human-machine interactions in a variety of future-work and education contexts. This paper presents a systems model for a no-code AR systems framework that can be used to create AR applications that present just-in-time informatics to assist and guide users in the completion of complex task sequences while ensuring operator and environment safety. The salient structural and behavioral aspects of the system, and key use cases are modeled using the Systems Modeling Language (SysML). Representative examples of the model are presented using use case, block definition, internal block, activity, and state-machine diagrams. These models offer new insights into how AR capabilities can be integrated with a variety of engineered systems. In the future such SysML models can steer the design of new tools and an ontology to strengthen connections to domain knowledge. 

Recent advances in Augmented Reality (AR) devices and their maturity as a technology offers new modalities for interaction between learners and their learning environments. Such capabilities are particularly important for learning that involves hands-on activities where there is a compelling need to: (a) make connections between knowledge-elements that have been taught at different times, (b) apply principles and theoretical knowledge in a concrete experimental setting, (c) understand the limitations of what can be studied via models and via experiments, (d) cope with increasing shortages in teaching-support staff and instructional material at the intersection of disciplines, and (e) improve student engagement in their learning. AR devices that are integrated into training and education systems can be effectively used to deliver just-in-time informatics to augment physical workspaces and learning environments with virtual artifacts. We present a system that demonstrates a solution to a critical registration problem and enables a multi-disciplinary team to develop the pedagogical content without the need for extensive coding. The most popular approach for developing AR applications is to develop a game using a standard game engine such as UNITY or UNREAL. These engines offer a powerful environment for developing a large variety of games and an exhaustive library of digital assets. In contrast, the framework we offer supports a limited range of human environment interactions that are suitable and effective for training and education. Our system offers four important capabilities – annotation, navigation, guidance, and operator safety. These capabilities are presented and described in detail. The above framework motivates a change of focus – from game development to AR content development. While game development is an intensive activity that involves extensive programming, AR content development is a multi-disciplinary activity that requires contributions from a large team of graphics designers, content creators, domain experts, pedagogy experts, and learning evaluators. We have demonstrated that such a multi-disciplinary team of experts working with our framework can use popular content creation tools to design and develop the virtual artifacts required for the AR system. These artifacts can be archived in a standard relational database and hosted on robust cloud-based backend systems for scale up. The AR content creators can own their content and Non-fungible Tokens to sequence the presentations either to improve pedagogical novelty or to personalize the learning. 

Recent advances in Augmented Reality (AR) devices and their maturity as a technology offers new modalities for interaction between learners and their learning environments. Such capabilities are particularly important for learning that involves hands-on activities where there is a compelling need to: (a) make connections between knowledge-elements that have been taught at different times, (b) apply principles and theoretical knowledge in a concrete experimental setting, (c) understand the limitations of what can be studied via models and via experiments, (d) cope with increasing shortages in teaching-support staff and instructional material at the intersection of disciplines, and (e) improve student engagement in their learning. AR devices that are integrated into training and education systems can be effectively used to deliver just-in-time informatics to augment physical workspaces and learning environments with virtual artifacts. We present a system that demonstrates a solution to a critical registration problem and enables a multi-disciplinary team to develop the pedagogical content without the need for extensive coding. The most popular approach for developing AR applications is to develop a game using a standard game engine such as UNITY or UNREAL. These engines offer a powerful environment for developing a large variety of games and an exhaustive library of digital assets. In contrast, the framework we offer supports a limited range of human environment interactions that are suitable and effective for training and education. Our system offers four important capabilities – annotation, navigation, guidance, and operator safety. These capabilities are presented and described in detail. The above framework motivates a change of focus – from game development to AR content development. While game development is an intensive activity that involves extensive programming, AR content development is a multi-disciplinary activity that requires contributions from a large team of graphics designers, content creators, domain experts, pedagogy experts, and learning evaluators. We have demonstrated that such a multi-disciplinary team of experts working with our framework can use popular content creation tools to design and develop the virtual artifacts required for the AR system. These artifacts can be archived in a standard relational database and hosted on robust cloud-based backend systems for scale up. The AR content creators can own their content and Non-fungible Tokens to sequence the presentations either to improve pedagogical novelty or to personalize the learning. 

The sulfate anion radical (SO 4 •– ) is known to be formed in the autoxidation chain of sulfur dioxide and from minor reactions when sulfate or bisulfate ions are activated by OH radicals, NO 3 radicals, or iron. Here, we report a source of SO 4 •– , from the irradiation of the liquid water of sulfate-containing organic aerosol particles under natural sunlight and laboratory UV radiation. Irradiation of aqueous sulfate mixed with a variety of atmospherically relevant organic compounds degrades the organics well within the typical lifetime of aerosols in the atmosphere. Products of the SO 4 •– + organic reaction include surface-active organosulfates and small organic acids, alongside other products. Scavenging and deoxygenated experiments indicate that SO 4 •– radicals, instead of OH, drive the reaction. Ion substitution experiments confirm that sulfate ions are necessary for organic reactivity, while the cation identity is of low importance. The reaction proceeds at pH 1–6, implicating both bisulfate and sulfate in the formation of photoinduced SO 4 •– . Certain aromatic species may further accelerate the reaction through synergy. This reaction may impact our understanding of atmospheric sulfur reactions, aerosol properties, and organic aerosol lifetimes when inserted into aqueous chemistry model mechanisms.