A novel approach to inverse design of wind turbine airfoils using tandem neural networks

The performance of a wind turbine and its efficiency majorly depends on wind-to-rotor efficiency. The aerodynamic design of the wind turbine blades using high-fidelity tools such as adjoint-computational fluid dynamics (CFD) is accurate but computationally expensive. It becomes impractical when the number of design variables increases for multidisciplinary optimization (MDO). Low-fidelity tools are computationally cheaper but are not accurate, especially in regions of adverse pressure gradient and reverse flows. Surrogate modeling has been used in many aerodynamic problems. We develop and apply a recent architecture of the deep learning module, tandem neural networks (T-NNs) for the inverse design of wind turbine airfoils. The T-NNs trained on CFD data for fully turbulent cases predict not only the performance parameters for the given airfoil geometry but also the airfoil geometry for a given design objective. This framework uses the entire performance polar for inverse design which ensures that the airfoil optimization is not a single-point optimization problem which is essential for practical design problems. The T-NNs are also optimized to include multiple constraints like maximum thickness and trailing edge (TE) thickness which is a novel contribution in the field of inverse design using surrogate models. A statistical analysis is also performed to predict a family of airfoil geometries.https://doi.org/10.1002/we.291

Small Business Development Along the Blue Line in Prince George’s County

Final Project for PLCY400: Senior Capstone (Spring 2024). University of Maryland, College ParkFor our Public Policy Senior Capstone, this report analyzes how the Local Initiatives Support Corporation (LISC) can help build an ecosystem of support for local small businesses in Prince George’s County’s Blue Line Corridor. Specifically, our team focused on how to ensure local small businesses in the Capitol Heights and Seat Pleasant areas could stay and thrive amid incoming development. To explore this issue, we surveyed small businesses in Capitol Heights and Seat Pleasant to determine the issues they’re currently experiencing, the resources they can access, and further support they need. We determined that these businesses primarily need assistance with marketing and employment. This capstone project used background research, surveys/interviews, and data analysis to determine the best methods to support small businesses. It recommends that Prince George’s County government highlight these businesses through social media, newsletters, mail flyers, and Yellow Pages; address staffing issues by improving access to workforce systems, job recruiters, and grant programs; and that LISC helps facilitate and inform the creation of community development/business improvement organizations that lead to relationship building and resource allocation among local small businesses.Prince George’s Count

VOLUMETRIC SOLAR ABSORBING FLUIDS AND THEIR APPLICATIONS IN TWO-PHASE THERMOSYPHON

A two-phase thermosyphon is a passive system utilizing gravity to transfer working fluids. The working fluids of a two-phase thermosyphon must undergo vaporization and condensation in the same system. Two-phase thermosyphons can also be used as solar collectors. Traditional solar collectors utilize surface absorbers to convert incident solar radiation into thermal energy, but those systems feature a large temperature difference between the surface absorbers and heat transfer fluids, resulting in a reduction in the overall thermal efficiency. Volumetric solar absorbing fluids serve both as solar absorbers and heat transfer fluids, therefore significantly improving the overall efficiency of solar collectors. Comparing to pure fluids, nanofluids possess both enhanced thermal conductivity and solar absorption capacity as volumetric absorbing fluids. Nanofluids, when serving as volumetric solar absorbing fluids, are so far reported to work only at relatively low temperatures and in a single-phase heat transfer regime due to stability issue. This research investigates the possibility of using nanofluids, especially graphene oxide (GO) nanofluids, as volumetric solar absorbing fluids in two-phase thermosyphons. Despite their reputation as both stable and solar absorptive among nanofluids, graphene oxide nanofluids still deteriorate quickly under boiling-condensation processes (~100 °C). The solar transmittance of the GO nanofluids declines from 38 to 4%, during the first 24 h of testing. Further investigation shows that the stability deterioration is caused by the thermal reduction of GO nanoparticles, which mainly featured with de-carboxylation and de-hydroxylation. A commercial dye named acid black 52, when dissolved in water, exhibits great broadband solar absorption properties and excellent stability. It remains stable for over 199 days in two-phase thermosyphon, and their transmittance in solar spectral region varies less than 9%. The stability of acid black 52 aqueous solution is further confirmed with the 191-day enhanced radiation test, as it shows less than 5% transmittance change in solar spectral region

AI and Ted Bundy: Exploring Artificial Intelligence usage in criminal profiling

Poster presentation at the Undergraduate Research Day 2024.We have seen a meteoric rise in Artificial Intelligence (AI) creation and usage; yet little attention has been paid to using AI for societal benefits. To leverage AI in new ways, this study focused on integrating AI in criminal profiling. We assessed the accuracy of AI-generated profiles by modifying well-documented criminal cases with a known, and convicted, perpetrator to compare to published perpetrator data created by (human) experts. Using profiling inputs from the crimes of infamous serial killer Theodore ‘Ted’ Bundy, we prompted ChatGPT 3.5 to create profiles for the first eight attacks Bundy committed and compared the accuracy of the outputs to the known information. Initial results show AI creates vague but detailed, and fairly accurate, profiles compared to known information from cases and can find patterns between crimes. But, these profiles were created with specific prompts and the prompt type impacted accuracy. Our findings suggest that using AI in profiling warrants further research and consideration in ongoing investigations, potentially saving time and lives. Caution is advised given the limitations regarding specificity of details and we do not yet know if human-generated profiles are more accurate as we only compared the AI profiles to known information. Future research should compare AI-generated profiles with human-generated profiles and explore paid versions of AI that might reveal further capabilities which might be useful in law enforcement, where costs of using AI may be nominal, especially in relation to the savings of lives and in manpower hours

Magnetic and Toroidal Symmetry of Lithium Transition Metal Orthophosphates

LiCoPO4 is the foremost candidate material for a novel type of ferroic ordering calledferrotoroidicity. In this work, the synthesis of polycrystalline sample of LiCoPO4 is discussed, along with the structural analog LiMnPO4. Their magnetic susceptibility and magnetic structure were determined and analyzed and found to be consistent with previous reports on single crystal materials. This work also provides a thorough introduction to ferrotoroidicity, a history of its theoretical development, and a summary of the most studied candidate materials. The work then presents a detailed methodology for determining the toroidal structure which would result for the magnetic structure in candidate ferrotoroidal materials. The model provides a method for determining how many toroidal moments would be present, where they would be located within the unit cell, and along which crystallographic direction they would be oriented. Detailed examples for determining the magnetic structure are provided for LiCoPO4 and analogous structures with the olivine structure type, as well as several structures with the pyroxene structure type. The results demonstrate a method for understanding ferrotoroidal arrangements, anti-ferrotoroidal arrangements and non-toroidal structures

Future reference 'without' future morphology

In some languages, present morphology can be used to refer to non-scheduled future events. Since this form of future reference is constrained to certain subordinate environments, like conditional antecedents (‘If John gets a new job, he played his cards right’) and relative clauses (‘Everyone who gets invited to this party is very lucky’), I propose to call the phenomenon Subordinate Future (SF). Two factors have hindered our understanding of the SF: First, the SF often occurs in modalized sentences, which makes it difficult to tease apart its contribution from that of the environment. Second, present morphology in English can express several readings; therefore, the appearance of this future is not particularly informative. This dissertation brings new intra- and cross-linguistic evidence to bear on the nature and the meaning of the SF. I observe that, in addition to temporal displacement, the SF also introduces modal displacement. Then, I argue that the source of this modality is a subjunctive mood morpheme, which is silent in English, but pronounced in Portuguese. I proceed to decompose the semantics of the subjunctive. I propose that the subjunctive should be treated as a Heimian indefinite (Heim, 1982) ranging over situations. Simply put, the role of the subjunctive is to introduce a situation variable. The motivation for my proposal comes from the behavior of the subjunctive in relative clauses, and from the anaphoric pattern of sentences with the SF. In relative clauses, the SF blocks a specific reading of the DP. Besides that, the SF seems to be able to ‘bind’ the situation variable of predicates outside of its domain of c-command, giving rise to modal donkey anaphora. These two facts would be difficult to reconcile with a quantificational treatment of the subjunctive. I then turn my attention to the temporal interpretation of the phenomenon. As Crouch (1993, 1994) observed, this future is also able to anchor the temporal interpretation of clauses outside of its domain of c-command. I propose that this effect is a byproduct of modal donkey anaphora, and demonstrate how casting my proposal in terms of situations provides a natural account of the phenomenon. I conclude with a comparison between my proposal and existing accounts

Campus Oasis: A Sanctuary for Learning & Wellness

The relationship between the built environment and its occupants can have a negative and positive effect on their wellbeing. Students across all college campuses experience stress, depression, and anxiety. The stress of academia can be impacted from the built environment, however, the spaces we decide to be in can relieve the stress if designed properly. Mental health support for students is a critical issue that can be addressed architecturally with biophilic design. The goal of this thesis is to explore the relationships between environmental psychology and the built environment to design spaces that improve the occupant’s well-being. The architecture embodies wellness shared with the natural and built environment with the focus on the user experience. Concepts such as phenomenology and biophilic design will be applied to design a welcoming and healing environment. The design of a spa and wellness center will function as a haven for the students and staff of an institution to decompress, relax, learn, feel motivated and feel relieved. The project will become a precedent for other colleges and universities to support their community against mental health issues

ESSAYS ON THE ECONOMICS OF EDUCATION

In this dissertation, I examine various factors shaping students’ trajectories and opportunitieslater in life. In Chapter 1, I explore the role of grade retention policies. Grade retention as a remedial policy is controversial because the benefits of extra instruction time may not outweigh its costs. Previous research has primarily examined retention for specific grades. By exploiting plausibly exogenous variation in retention generated by a nationwide promotion policy in Chile, I demonstrate that retention timing is critical in determining its effect on academic performance and access to higher education. Being held back only reduces the probability of future grade retention for young primary students. Additionally, older primary students are less likely to return to school the following academic year or graduate from high school. High school grade-retained students are the most affected, with a 10-20 percentage point reduction in their likelihood of high school graduation, and many switch to adult education in response to retention. Interestingly, even though high school students who are held back are just as likely to take the college admission test, they show a positive 0.1 SD increase in Spanish and math performance. Then, in Chapter 2, I focus on the impact of massive and sudden school closures followingthe 2011 nationwide student strike in Chile on teenage pregnancy. We observe an average increase of 2.7% in teenage pregnancies in response to temporary high school shutdowns, equal to 1.9 additional pregnancies per lost school day. The effect diminishes after three quarters since the strike’s onset. The effects are predominantly driven by first-time mothers aligned with highschool absenteeism periods and are unrelated to the typical seasonality of teenage fertility or pregnancies in other age groups. Additionally, we document that the strike had a larger disruptive role by affecting students’ educational trajectories, evidenced by a persistent increase in dropout rates and a reduction in college admission test take-up for both female and male students. Lastly, in Chapter 3, I explore inequalities in performance associated with the school typestudents attend, particularly the contribution of teachers to student performance in Chile’s college admission test (PSU). Our analysis is based on a unique teacher-student matched dataset and decomposition methods. The findings suggest that teachers’ performance on the PSU and the characteristics of their educational degrees are significant predictors of students’ success. When controlling for students’ and predetermined school characteristics, the gap between voucher and public schools reduces. Productivity differences emerge as key factors driving the disparities across school types. The analysis underscores the crucial role of teacher-student interactions in shaping student outcomes

Winter Soldiers and Moonlight Rebels

How do rebel groups cultivate devotion? Civil conflict scholars have found that when rebel groups fill their ranks with ideologically committed soldiers they are able to operate more effectively in several ways. However, the mechanisms by which rebel groups attain such devoted followers remains unexplained. I propose that insurgencies are able to cultivate devotion when they successfully deploy an ideology that balances between explanatory power and complexity. An ideology that manages to make sense of a political environment with minimal complexity provides adherents with certainty, which is a source of substantial utility. Groups that deploy maximally potent ideologies foster the emergence of a "hard core" of soldiers who depend upon the certainty afforded by the ideology and will therefore go to great lengths to act on its behalf. I articulate a theory of ideological potency and propose an associated function that expresses how much utility an individual will derive from that ideology via its certainty mechanism. I then analyze and compare the PIRA, the Viet Minh and Renamo insurgencies to demonstrate how variation in the extent to which they effectively balanced between explanatory power and complexity in their ideologies can explain variation in their capacity to attract, generate, control, and sustain devoted soldiers

Characterization of a novel Escherichia coli exopolysaccharide and its biosynthesis by NfrB

Biofilms are made from an association of bacterial cells and extracellular products dominated by a plethora of exopolysaccharides. Accumulating evidence have demonstrated that the bacterial second messenger cyclic-di-guanosine monophosphate (c-di-GMP) promotes the synthesis of these exopolysaccharides through direct allosteric activation of glycosyltransferase enzymes. The Escherichia coli inner membrane protein NfrB, which together with the outer membrane protein NfrA acts as a receptor system for phage N4, contains a N-terminal glycosyltransferase domain and C-terminal c-di-GMP binding domain. Recent research revealed that NfrB is a novel, c-di- GMP controlled glycosyltransferase that is proposed to synthesize a N-acetylmannosamine containing polysaccharide product, though the exact structure and function of this remains unknown. Nfr polysaccharide production impedes bacterial motility, which suggests a possible role of the Nfr proteins in bacterial biofilm formation. Here, we carry out in-vivo synthesis of novelNfr polysaccharide followed by its structural characterization. Preliminary data from MALDI- TOF mass spectrometry and Solid State 13C NMR spectroscopy indicated that the Nfr polysaccharide is mainly a homo polymer of poly-?-(1®4)-N-acetylmannosamine, bound to an aglycone. In addition, we report efforts to develop of a Nfr polysaccharide binding and detection tool, through the mutation of YbcH, a putative Nfr polysaccharide hydrolase enzyme. These studies advance the understanding of Nfr polysaccharide biosynthesis and could offer potential new targets for the development of antibiofilm and antibacterial therapies