Analyses and modeling of a fire-protection foam and gel

Stubbs, Laura Denise University of Maryland College Park 2001 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Fire-protection agents are used to protect buildings or structures that are exposed to fire. Basic requirements of these agents are to adhere to surfaces and maintain their cohesiveness and properties while they are exposed to a fire. Fire-protection agents are subjected to high radiant heat fluxes. The radiant energy is absorbed, transmitted (conducted), and reflected as the agent recedes. This thesis presents the experimental results of two such agents, a protein-based foam and a gel. Additionally, aluminum powder pigments were added to the agents to enhance their performance by reducing the effect of the radiant heat, thus protecting the underlying structure for a longer period of time. Tests were performed and models were developed to analyze the effectiveness of both agents as well as the added effectiveness, if any, of the enhancements. A method was also developed to quantify the percentage improvement. When subjected to radiant heat corresponding to the heat flux for the onset of fire of typical building materials, the temperature profile in the foam exhibited four (4) distinct sections of interest while protecting the underlying surface. An analytical model was proposed for the temperature profile for the first two (2) of the four (4) sections. The model provided very good agreement during the heat up section and only adequate agreement during the evaporation section of the temperature profile where it overpredicted the temperature. However, at a higher transitional heat flux, the analytical model will not predict the temperature profile in the foam. At and above such a heat flux, the mean penetration length is effectively zero and the foam immediately experiences evaporation thus not allowing much time for a temperature profile, due to conduction, to form in the foam. Aluminum pigments were later applied to the foam surface. The pigments increased the reflectivity of the foam surface, thus decreasing the heat flux absorbed and conducted by the foam. This improved the foam performance by as much as 20%. This result was also previously seen by Boyd, another experimenter in our same laboratory using a different test method. By contrast, the temperature profile of the plate on which gel was placed exhibited three characteristic behaviors. A computational model was written that accurately predicted the temperature of the underlying surface during 2 of the 3 sections; however, there were variations between the temperature predicted by the model and the actual temperature profile during the middle section. When the same pigments that were added to the foam were added to the gel, the gel performance was actually degraded in some cases. An effectiveness ratio was defined and average values were calculated for both agents. A comparison of the two agents showed that the foam provided more effective protection to the underlying structure by maintaining the surface at a lower temperature than that felt by the gel for a longer period of time when subjected to the same heat fluxes.

A validation of resilient progression in the general population and in ballroom dancers

Stubbs, Christopher Rand The University of Utah 2005 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

A subset of recent research in resilience appears to overlap with research in spiritual wellness and defines resilience as an innate force that drives individuals to seek self-actualization through harmonizing with a source of spiritual strength, likely including a form of the collective unconscious, nature, deity, or universal energy. This study examined the validity of resilience constructs and associated predictive paths that directly relate to the degree and nature of the connection one has with a source of spiritual strength. These constructs include essential resilience (sense of physical security), childlike resilience (ability to be playful and trusting), ecological resilience (environmental security), moral resilience (degree of comfort with one's value system), synergistic resilience (social focus and identity), noble resilience (purpose in life), divine resilience (identifying with a power or force beyond oneself), and orchestrational resilience (helping others to become aware of broader perspectives and sources of emotional, social, and spiritual strength). This study also examined social and ballroom dancing as a means of fulfilling resilient, or spiritual, drives. Two hundred seventy-six college-aged adults from two Utah colleges were divided into a group of advanced social and ballroom dancers and a group representative of the general population. Each participant completed a questionnaire comprised of 14 measurement instruments. Structural equations modeling (SEM) allowed the strength of individual relationships within hypothesized structural models to be assessed. Three nomologically valid models were established for the general sample and for men in the study. The model of best fit for the general sample retained the moral, noble, synergistic, childlike, divine, and orchestrational resilience constructs; essential and ecological resilience dropped out of the theoretical models. The model of best fit for the general sample was used as a baseline for comparative analysis between dancers and the general population. Differences were found between the general sample and dancers. Differences were also found between men and women in the study. Moral resilience predicted noble resilience and noble resilience predicted divine and orchestrational resilience in all valid models. Finally, progressive models appeared to provide a better fit to the data than a competing cumulative model.

Development of an acoustic wave based biosensor for vapor phase detection of small molecules

Stubbs, Desmond Georgia Institute of Technology 2006 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

For centuries scientific ingenuity and innovation have been influenced by Mother Nature's perfect design. One of her more elusive designs is that of the sensory olfactory system, an array of highly sensitive receptors responsible for chemical vapor recognition. In the animal kingdom this ability is magnified among canines where ppt (parts per trillion) sensitivity values have been reported. Today, detection dogs are considered an essential part of the US drug and explosives detection schemes. However, growing concerns about their susceptibility to extraneous odors have inspired the development of highly sensitive analytical detection tools or biosensors known as "electronic noses". In general, biosensors are distinguished from chemical sensors in that they use an entity of biological origin (e.g. antibody, cell, enzyme) immobilized onto a surface as the chemically-sensitive film on the device. The colloquial view is that the term "biosensors" refers to devices which detect the presence of entities of biological origin, such as proteins or single-stranded DNA and that this detection must take place in a liquid. Our biosensor utilizes biomolecules, specifically IgG monoclonal antibodies, to achieve molecular recognition of relatively small molecules in the vapor phase.

Rescuing "endangered girls": Bourgeois feminism, social welfare, and the debate over prostitution in the Weimar Republic

Stubbs, Julie R University of Michigan 2001 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

After ten years of Reichstag debate, the 1927 German Law to Combat Venereal Disease (RGBG) replaced a system of state-regulated prostitution with health and welfare initiatives to control promiscuity. This study examines bourgeois feminist contribution to Weimar prostitution policy, focusing on the activities of the German Branch of the International Abolitionist Federation (abolitionists), whose activism helped to ensure that the RGBG decriminalized prostitution and established social programs for “morally endangered” women. The work aims to provide insight into bourgeois feminist participation in the German welfare state, and the implications of “social motherhood” as an emancipatory vehicle for women. “Rescuing ‘Endangered Girls’” traces the transformation of abolitionists from political outsiders critical of state policy to welfare administrators acting with state power. The first section chronicles the protracted battle to dismantle state-regulated prostitution in Germany, beginning with the development of feminist, public health and moral reform anti-regulation pressure groups in the 1890s. Tracing the wartime concerns about shifting moral standards and the hygienic threat of venereal disease, which garnered support for the RGBG, this section explores the ten-year Reichstag debate over the law's provisions, revealing a nation divided over moral issues. The second part examines the bourgeois feminist establishment of welfare programs for prostitutes and “morally endangered” girls, services later mandated by the RGBG. Through analysis of social scientific studies of female sexual deviance, this section also explores the class, gender, and generational anxieties that underlie abolitionist welfare services. While male bureaucrats came to dominate Weimar welfare services, bourgeois feminists maintained control of the welfare programs for the endangered, imprinting the German welfare state with their vision of social motherhood. Based on a theory of essentialized gender differences positing women as naturally moral, social motherhood called on women to serve German society through “caring” professions, thus justifying the employment of women as social workers, doctors and police officers with welfare programs for the endangered. However, the gender essentialism on which abolitionist welfare services were based naturalized bourgeois moral and social norms, fostering an intolerance of differences among women. Consequently, abolitionists viewed any sexually independent woman as either socially deviant or mentally ill.

Fundamental Studies of Competitive Equilibria at Silica Surfaces

Stubbs, Barrack Perez Michigan State University ProQuest Dissertations & 2019 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The fundamental interactions such as physisorption at solid-liquid interfaces are not fully characterized. The physical properties and chemical reactivity at the silica surface is one that is subject to much investigation. A variety of analytical techniques, including solid state nuclear magnetic resonance (SS-NMR ) and high-performance liquid chromatography (HPLC) were utilized to help characterize the surface of silica. These techniques were combined in order to understand the fundamental mechanisms of surface interactions such as adsorption mechanisms and chemical reactivity. The pH, ionic strength, and mobile phase compositions were varied throughout the experiments as a basis for assessing reactivity.The SS-NMR data shows a correlation between pH and labile surface hydrogens. At higher pH values, the transfer of excitation from labile surface hydrogens to surface silicon atoms is diminished. A change in peak ratios that correspond to labile primary silanols and surface bridging siloxanes was observed. The relative concentration of bridging siloxanes is constant whereas the signal from primary silanols is greatly diminished.Aqueous, normal-phase HPLC shows the various interactions of phenol with the silica surface. Multiple peaks were generated from a single analyte when the water/methanol concentration was at least 20%/80%. At 90% and 100% methanol, a single peak is shown for phenol. The ratio and number of peaks depends on conditions such as solvent composition, pH, ionic strength, flow rate, and temperature. We argue that the distribution of surface silanol sites is responsible for the generation of multiple peaks that are seen in the extreme aqueous conditions. These sites, as well as the water in the mobile phase, modify the mass transport term in the Van Deemter equation. The conditions and results obtained in these experiments are explained below with an emphasis on mass transport.Additionally, other analytical techniques such as scanning electron microscopy, thermogravimetric analysis, and inductively coupled plasma were used to help characterize the silica surface. Through these techniques, values for surface silanol concentration ranging from 1.6關mol/m2 to 7.0關mol/m2 were obtained. The physical morphology of the silica surface was also characterized before and after exposure to basic environments.

On Exponentially Localized Wannier Functions in Non-Periodic Insulators

Stubbs, Kevin D ProQuest Dissertations & Theses Duke University 2021 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Exponentially localized Wannier functions (ELWFs) are an orthogonal basis for the low energy states of a material consisting of functions which decay exponentially quickly in space. When a material is insulating and periodic, conditions which guarantee the existence of ELWFs in dimensions one, two, and three are well-known and methods for constructing ELWFs numerically are well-developed. In this dissertation, we consider the case where the material is insulating but not necessarily periodic and develop an algorithm for calculating ELWFs.In Chapter 3, we propose an optimization-free algorithm for constructing Wannier functions in both periodic and non-periodic insulating systems. In this chapter, we rigorously prove that under the assumption of "uniform spectral gaps'', a technical assumption we introduce, that our algorithm constructs ELWFs.While the uniform spectral gaps assumption is not always met in practice, in Chapter 4, we prove that for a wide class of systems (both periodic and non-periodic) it is always possible to modify our algorithm so that the uniform spectral gaps assumption holds. As a consequence of this result, we conclude that for both periodic and non-periodic systems our algorithm can construct ELWFs whenever they exist.The results in this dissertation open the door for extending the theory of topological insulators, a recently discovered class of materials, to fully non-periodic systems.

Technical text: Improving comprehensibility through the application of psycholinguistic research

Stubbs, Nancy A University of Southern California 2001 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

<italic>Purpose</italic>. The purpose of the study was to determine whether the guidelines taken from psycholinguistics and used to modify the selected text passage would have a relationship to the subjects' comprehension of technical text. The secondary purpose was to ascertain whether there was a relationship between the measures of comprehension accuracy and length of reading time. A tertiary purpose was to determine whether the guidelines taken from psycholinguistics and used to edit the selected text passage would enhance the comprehension of participants with poor reading ability and subjects with little, if any, prior knowledge. <italic>Method</italic>. The experimental group was exposed to a technical manual on electricity and electronics that had been edited for clarity from application of psycholinguistic principles (the edited text), whereas the comparison group received an unedited version of the text (the unedited text) having the same basic content as that of the edited text. Prior to the administration of the same posttests to each of the two samples, the score was obtained from each participant indicating how much time he or she had spent in reading the passages of the assigned technical material. Two posttests were administered to each of the two samples: (a) a twenty-three item multiple-choice examination designed to assess understanding of the edited and unedited texts and (b) a twenty-five item reading attitude measure in Likert format given last and intended to reflect the extent to which the respondents expressed what could be considered positive feelings toward the activities. <italic>Findings</italic>. Comparisons were made between the means of the experimental and comparison groups on all five measures employed and evaluated for statistical significance. No apparent statistically significant differences were found between the experimental and comparison groups on the posttest of accuracy of reading comprehension or with the time scores. The difficulty level of the technical text used in this study was questioned and offered as a plausible reason for the apparent lack of statistical significance in the findings. It is the opinion of this researcher that grounds exist for further studies of this type.

Emotional intelligence competencies in the team and team leader: A multi-level examination of the impact of emotional intelligence on group performance

Stubbs, Elizabeth Christine Case Western Reserve University 2005 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

This research examines the relationship between team leader emotional intelligence competencies, team level emotional intelligence, and team performance. It is argued here that team leader's emotional intelligence (EI) will influence the development of group level emotional intelligence, which was measured by a teams emotionally competent group norms (ECGN). Secondly, it is hypothesized that the presence of ECGNs will positively influence group effectiveness. Data were collected from 422 respondents representing 81 teams in a military organization. Results show that team leader emotional intelligence is significantly related to the presence of emotionally competent group norms on the teams they lead, and that emotionally competent group norms are related to team performance. This research contributes to the field by offering support for the affects team leaders emotional intelligence has on the teams they lead as well as by showing team level emotional intelligence affects team performance. Propositions for future research and practice are offered.

Robot-Proxy Grounding

Stubbs, Kristen Carnegie Mellon University 2008 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Exploration robotics has traditionally utilized an encoder-decoder model of communication between users and a robot. This means that users construct a plan (sequence of actions) to be sent to the robot; the robot executes the plan and returns data to the users, who then construct another plan. The problem with this interaction paradigm is twofold: (1) users must develop a complex mental model of the robotic system in order to create intricate plans, and (2) the robot does not have the users' specialized domain knowledge, so the robot does not have any way to ensure that how it handles unexpected events in the field is consistent with the users' goals (what the users are trying to accomplish). Because the cost of communication with the remote robot is extremely high, this work introduces the concept of a "robot proxy," a software system which models both the robot's capabilities and the user's goals. The robot proxy interacts with the user in real-time in place of the robot so as to promote mutual knowledge between the two. This process, referred to as Robot-Proxy Grounding, is a novel interaction model for exploration robotics derived from Herbert Clark's theory of common ground and from detailed observations and analysis of the Life in the Atacama exploration robotics project. This analysis indicated that the majority of the errors and miscommunications which occurred during the project were related to a lack of common ground between participants. A proof of concept study was conducted which compared the effects of an encoder-decoder planning system and a prototype robot proxy; the study suggested that using the robot proxy resulted in improved task efficiency and fostered feelings of collaboration. A full implementation of a robot proxy was constructed and evaluated. The results indicated that participants who used the robot proxy were more efficient at the task, collected higher-quality data, and possessed more accurate information about the robot's state and context than participants without a robot proxy. The results suggest that the implementation was successful at promoting common ground with the user, resulting in improved task performance.

Simulations of microheterogeneous fluids

Stubbs, John Michael University of Minnesota 2004 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The hydrogen-bonding interaction is a strong and directional interaction that dominates the association of many molecules. Alcohols, having a hydroxyl head group attached to a nonpolar tail, associate in both neat liquids and solutions and form a variety of molecular aggregates depending on molecular structure and thermodynamic state point (temperature, pressure, and composition). Alcohol aggregates in dilute nonpolar solutions have found direct technological application due to their ability for enhancing a supercritical fluid's solvating power or solubilizing water contamination in fuel mixtures. The primary goals of this dissertation research are to examine hydrogen-bonded aggregates and provide molecular-level insight into their behavior and properties using Monte Carlo simulation, as well as to develop transferable force fields including molecules capable of forming intramolecular hydrogen bonds. Chapter I outlines the basic computer simulation methodologies employed in the research, with more advanced methodologies covered in chapter II. Chapter III describes the implementation of a Monte Carlo algorithm to sample the spatial distribution of molecules. Chapter IV introduces new molecular force fields for molecules containing ether, ether + alcohol and nitrile functionalities. Chapter V discusses applications of Monte Carlo simulations to a variety of hydrogen bonding systems including methanol in supercritical carbon dioxide, hexanol isomers in n-hexane, alkoxyethanols in n-hexane, and neat alkoxyethanols. An in-depth analysis of hydrogen-bonded aggregates is presented including aggregate size distribution, temperature and pressure dependencies, and energetics. Chapter V also presents a study of the vibrational spectra of hydrogen-bonded 1-hexanol aggregates using Car-Parrinello molecular dynamics simulations. Finally, an ab initio investigation of the formation of the glycosidic bond in methyl-beta-D-glucopyranose is described.