Propellant tank pressurization modeling for a hybrid rocket

A basic hybrid rocket oxidizer delivery system utilizes the self-pressurizing nature of a liquid oxidizer at ambient temperatures in conjunction with a non-condensable pressurant to provide a high oxidizer tank pressure that drives liquid oxidizer flow to the combustion chamber. In this study, the oxidizer fluid is nitrous oxide which produces high vapor pressures at ambient temperatures, and helium is the pressurant. The goal of this thesis is to provide a theoretical model that predicts the pressure draining history of the oxidizer tank to within ± 5% of experiment. The validity of simple thermodynamically-based models has not been considered for self-pressurizing, draining propellant tanks under high pressure conditions. In this study, two models are produced, both assuming thermodynamic equilibrium states at every point in time throughout draining. The first model assumes the P-V-T behavior of the nitrous oxide/helium mixture is ideal; the second model assumes that the mixture adheres to the non-ideal Peng-Robinson equation-of-state. Both models are compared to experimental data from pure nitrous oxide draining tests, published in G. Zilliac and M. Karabeyoglu (Modeling of Propellant Tank Pressurization, AIAA 2005-3549, 41st AIAA/ASME/ASEE Joint Propulsion Conference). Theoretical draining histories for the Peregrine hybrid sounding rocket (a joint effort between NASA Ames Research Center and Stanford University), soon to be launched from NASA Wallops Flight Facility, have also been examined. A variety of comparisons with available experimental data, theoretical sensitivity studies, and theoretical launch data demonstrates that the non-ideal draining model provides favorable agreement. The additional complexity introduced by a non-ideal equation-of-state is necessary due to the high pressures encountered in the tank during draining. It is found that despite the highly nonlinear nature of the draining process, the liquid flow rate from the tank remains reasonably constant, which is a highly desirable characteristic of a rocket oxidizer delivery system

Crime prevention and the perception of safety in campus design

The objectives of this research are to demonstrate the process of applying perception of safety in a campus environment to actual crimes and to use the results to better implement safety improvements within the campus landscape. The focus of the research is the outdoor environment on a college campus. The Louisiana State University campus was selected as a case study. The survey was developed and tested to better understand how people perceive their surroundings and to incorporate the findings of perception of safety to improve design and planning decisions for the LSU campus. The criteria for a safe design was developed from research gathered on crime prevention and the psychological reactions of users to exterior site features. Crimes reported on the LSU campus were compiled on a crime map in order to analyze whether student perceptions of unsafe and safe areas were justified. The hope of this thesis is to enlighten designers on the subject of crime prevention and the perception of safety in the landscape. Further research on the LSU campus that leads to actual improvements of public safety is encouraged for persons involved in campus planning and maintenance

Mechanism Of Nucleosome Targeting By Pioneer Transcription Factors

Transcription factors (TFs) forage the genome to instruct cell plasticity, identity, and differentiation. These developmental processes are elicited through TF engagement with chromatin. Yet, how and which TFs can engage with chromatin and thus, nucleosomes, remains largely unexplored. Pioneer TFs are TF that display a high affinity for nucleosomes. Extensive genetic and biochemical studies on the pioneer TF FOXA, a driver of fibroblast to hepatocyte reprogramming, revealed its nucleosome binding ability and chromatin targeting lead to chromatin accessibility and subsequent cooperative binding of TFs. Similarly, a number of reprogramming TFs have been suggested to have pioneering activity due to their ability to target compact chromatin and increase accessibility and enhancer formation in vivo. But whether these factors directly interact with nucleosomes remains to be assessed. Here we test the nucleosome binding ability of the cell reprogramming TFs, Oct4, Sox2, Klf4 and cMyc, that are required for the generation of induced pluripotent stem cells. In addition, we also test neuronal and macrophage reprogramming TFs. Our study shows that reprogramming TFs bind nucleosomes with a range of nucleosome binding affinities, indicating that although specific cocktails of TFs are required for reprogramming, mechanistically these TFs show differential nucleosome interacting behaviors. These results allowed us to assess differential features between TFs nucleosome binding ability and to correlate their binding with reprogramming potential. To determine how general is nucleosome binding we extended our analysis to screen 593 of the 2,000 predicted human TFs in the genome for potential nucleosome binding and validated their binding in solution. Based on 3D structural analysis, we proposed that strong nucleosome binders anchor DNA through short -helixes and have a flexible and adaptable DNA binding domain while weak nucleosome binders use -sheets or unstructured regions and have a higher rigidity within their DNA binding domain. Through the experiments presented in this dissertation we present the first study revealing the shared structural features contributing to nucleosome binding potential of pioneer TFs and thus allow for predication of novel pioneer TFs with cell reprogramming potential

Relationships Between Social Self-Esteem, Media Influence and Drive for Thinness

Although media exposure is known to relate to drive for thinness and social self-esteem in women, less is known about how media affects drive for thinness and social self-esteem in men. The present study examined the relationships between drive for thinness, social self-esteem, and media influence among men and women. Two hundred ninety-four college students completed the Texas Social Behavior Inventory, the Sociocultural Attitudes towards Appearance Scale-3, a self-constructed questionnaire measuring the influence of media models, and the Drive for Thinness scale of the EDI-3. We expected to find an association between drive for thinness and media influence and between drive for thinness and social competence in both men and women. In addition, we expected that the use of media, social pressures and media internalization would relate to drive for thinness in both men and women. As expected, we found a relationship between media influence and drive for thinness, as well as a relationship between social competence and drive for thinness in both men and women. After controlling for the influence of social self-esteem, the influence of media models on body image related to drive for thinness in both men and women. In addition, societal pressures related to drive for thinness in women, but not men. Implications for college counselors will be discussed

Utilizing Standardized Patient Feedback to Facilitate Professional Behavior in Physical Therapist Students: A Pilot Study

Purpose: Physical therapist (PT) students receive feedback on professional behavior performance from academic and clinical faculty members. Literature is lacking on the impact that verbal feedback from standardized patients (SPs) may have on physical therapist student learning of professional behaviors. The purpose of this pilot study was to examine the use of standardized patients’ feedback as a strategy for professional behavior development. Methods: A sample of convenience identified 13 doctoral physical therapist students prior to initiation of their first full-time clinical experience. Subjects were excluded if they had prior experiences with standardized patients or had completed a full-time clinical experience. Using a randomized control design, the experimental group (n=7) received standardized patient verbal feedback and written rubric assessment, whereas the comparison group (n=6) received written rubric assessment alone after completing standardized patient case scenarios. Outcome measures included the Modified Standardized Patient Satisfaction Questionnaire (MSPSQ), Professional Behaviors Assessment (PBA), and Professionalism Physical Therapy Core Values Assessment (PPTCVA). Results: Data analysis included pre and post intervention comparisons of Modified Standardized Patient Satisfaction Questionnaire rubric assessment scores, Professional Behaviors Assessment scores, and Professionalism Physical Therapy Core Values Assessment scores. No statistically significant differences were found on these outcome measures, although trends for changes in performance were noted. Conclusions: Limited research exists on the impact of standardized patients’ verbal feedback with the use of a standardized rubric on physical therapist student professional behavior. This pilot study did not provide significant evidence on the value of this educational strategy in development of professional behaviors in doctoral physical therapist students. Future research may be beneficial to examine differences in perceptions of professional behavior between standardized patients, students, and faculty

Time Advancement and Bounds Intersection Checking for Faster Broad-Phase Collision Detection of Paired Object Trajectories

For self-driving mechanisms, the motion planning requires a reasonably fast algorithm for collision detection along the trajectories. We present three algorithms for the detection of collision among objects with predefined trajectories. The first algorithm uses the intersection of the path’s bounding box. The second algorithm sequentially checks for intersection between each pair of corresponding axis-aligned bounding boxes (AABB) from the trajectories of the two paths. Lastly, the latter algorithm is modified using iterative time advancement to an estimated earliest possible collision time. Simulation experiments on a variety of pair trajectories demonstrate a significant speedup of the proposed algorithms over the existing baseline algorithm. They are, therefore, preferable alternatives for faster broad-phase collision detection in applications such as motion planning

Advanced Air Transport Technology (AATT)

The NASA Advanced Air Transport Technology (AATT) Project is advancing commercial subsonic technologies to meet future aviation economic and environmental goals. Part of the portfolio is focused on podded and integrated fan technology advancement. The AATT is discussing potential collaboration opportunities in the fan technology area with DLR (German Aerospace Center). This presentation will be used to facilitate these discussions

Development of an Electronic Nose for Olfactory System Modelling using Artificial Neural Network

Electronic nose (e-nose) devices have received considerable attention in the field of sensor technology because of their many potential uses such as in identification of toxic wastes, monitoring air quality, examining odors in infected wounds and in inspection of food. Notwithstanding the vast amount of literature on the usage of e-noses for specific purposes, the technology originally and ultimately aims to mimic the capability of mammals to discriminate odors from all sorts of objects. This study demonstrates the theoretical and practical feasibility of designing an e-nose towards general odor classification. A multi-sensor array hardware unit was carefully constructed for data collection and odor detection. Important hardware design considerations such as sensor calibration, aeration, circuit protection, and voltage/current requirements were satisfied. A highly fine-tuned artificial neural network (ANN) was integrated to the hardware to interpret and relate the data to a target odor class from a set of 10 primary odors identified in a previous study. Various network architecture considerations, such as neuron count, number of layers and activation function, as well as various data treatment methods, such as normalization, and data partitioning, were investigated. The results showed that careful hardware integration with an ANN having sufficiently deep internal structure can yield accurate classification to at least half of the ten primary odor classes, namely fragrant (96%), fruity (98%), chemical (99%), peppermint (98%), and popcorn (90%). The results demonstrate the feasibility of making e-noses for general odor classification, which could lead to further broadening of e-nose applications