Study of Mobile Robot Operations Related to Lunar Exploration

Mobile robots extend the reach of exploration in environments unsuitable, or unreachable, by humans. Far-reaching environments, such as the south lunar pole, exhibit lighting conditions that are challenging for optical imagery required for mobile robot navigation. Terrain conditions also impact the operation of mobile robots; distinguishing terrain types prior to physical contact can improve hazard avoidance. This thesis presents the conclusions of a trade-off that uses the results from two studies related to operating mobile robots at the lunar south pole. The lunar south pole presents engineering design challenges for both tele-operation and lidar-based autonomous navigation in the context of a near-term, low-cost, short-duration lunar prospecting mission. The conclusion is that direct-drive tele-operation may result in improved science data return. The first study is on demonstrating lidar reflectance intensity, and near-infrared spectroscopy, can improve terrain classification over optical imagery alone. Two classification techniques, Naive Bayes and multi-class SVM, were compared for classification errors. Eight terrain types, including aggregate, loose sand and compacted sand, are classified using wavelet-transformed optical images, and statistical values of lidar reflectance intensity. The addition of lidar reflectance intensity was shown to reduce classification errors for both classifiers. Four types of aggregate material are classified using statistical values of spectral reflectance. The addition of spectral reflectance was shown to reduce classification errors for both classifiers. The second study is on human performance in tele-operating a mobile robot over time-delay and in lighting conditions analogous to the south lunar pole. Round-trip time delay between operator and mobile robot leads to an increase in time to turn the mobile robot around obstacles or corners as operators tend to implement a `wait and see\u27 approach. A study on completion time for a cornering task through varying corridor widths shows that time-delayed performance fits a previously established cornering law, and that varying lighting conditions did not adversely affect human performance. The results of the cornering law are interpreted to quantify the additional time required to negotiate a corner under differing conditions, and this increase in time can be interpreted to be predictive when operating a mobile robot through a driving circuit

Computer Modeling of Direct Metal Laser Sintering

A computational approach to modeling direct metal laser sintering (DMLS) additive manufacturing process is presented. The primary application of the model is for determining the temperature history of parts fabricated using DMLS to evaluate residual stresses found in finished pieces and to assess manufacturing process strategies to reduce part slumping. The model utilizes MSC SINDA as a heat transfer solver with imbedded FORTRAN computer code to direct laser motion, apply laser heating as a boundary condition, and simulate the addition of metal powder layers during part fabrication. Model results are compared to available data collected during in situ DMLS part manufacture

From illegality to criminality: developing ‘rules’ under international law

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Additive Manufacturing Thermal Performance Testing of Single Channel GRCop-84 SLM Components

The surface finish found on components manufactured by sinter laser manufacturing (SLM) is rougher (0.013 - 0.0006 inches) than parts made using traditional fabrication methods. Internal features and passages built into SLM components do not readily allow for roughness reduction processes. Alternatively, engineering literature suggests that the roughness of a surface can enhance thermal performance within a pressure drop regime. To further investigate the thermal performance of SLM fabricated pieces, several GRCop-84 SLM single channel components were tested using a thermal conduction rig at MSFC. A 20 kW power source running at 25% duty cycle and 25% power level applied heat to each component while varying water flow rates between 2.1 - 6.2 gallons/min (GPM) at a supply pressure of 550 to 700 psi. Each test was allowed to reach quasi-steady state conditions where pressure, temperature, and thermal imaging data were recorded. Presented in this work are the heat transfer responses compared to a traditional machined OHFC Copper test section. An analytical thermal model was constructed to anchor theoretical models with the empirical data

Virtually Standing Up or Standing By? Correlates of Enacting Social Control Online

Research has consistently established the robustness of the bystander effect, or the tendency of individuals to not intervene on behalf of others in emergency situations. This study examines the bystander effect in an online setting, focusing on factors that lead individuals to intervene, and therefore enact informal social control, on behalf of others who are being targeted by hate material. To address this question, we use an online survey (N=647) of youth and young adults recruited from a demographically balanced sample of Americans. Results demonstrate that the enactment of social control is positively affected by the existence of strong offline and online social bonds, collective efficacy, prior victimization, self-esteem, and an aversion for the hate material in question. Additionally, the amount of time that individuals spend online affects their likelihood of intervention. These findings provide important insights into the processes that underlie informal social control and begin to bridge the gap in knowledge between social control in the physical and virtual realms

Thermal Performance Testing of Single Channel GRCop-84 SLM Components

The surface finish found on components manufactured by sinter laser manufacturing (SLM) is rougher (0.013 - 0.0006 inches) than parts made using traditional fabrication methods. Internal features and passages built into SLM components do not readily allow for roughness reduction processes. Alternatively, engineering literature suggests that the roughness of a surface can enhance thermal performance within a pressure drop regime. To further investigate the thermal performance of SLM fabricated pieces, several GRCop84 SLM single channel components were tested using a thermal conduction rig at MSFC. A 20 kW power source running at 25% duty cycle and 25% power level applied heat to each component while varying water flow rates between 2.1 - 6.2 gallons/min (GPM) at a supply pressure of 500 to 750 psi. Each test was allowed to reach quasisteady state conditions where pressure, temperature, and thermal imaging data were recorded. Presented in this work are the heat transfer responses compared to a traditional machined OHFC Copper test section. An analytical thermal model was constructed to anchor theoretical models with the empirical data

A Nanoscale Parametric Feedback Oscillator

We describe and demonstrate a new oscillator topology, the parametric feedback oscillator (PFO). The PFO paradigm is applicable to a wide variety of nanoscale devices and opens the possibility of new classes of oscillators employing innovative frequency-determining elements, such as nanoelectromechanical systems (NEMS), facilitating integration with circuitry and system-size reduction. We show that the PFO topology can also improve nanoscale oscillator performance by circumventing detrimental effects that are otherwise imposed by the strong device nonlinearity in this size regime

Effects on Inter-Personal Memory of Dancing in Time with Others.

We report an experiment investigating whether dancing to the same music enhances recall of person-related memory targets. The experiment used 40 dancers (all of whom were unaware of the experiment's aim), two-channel silent-disco radio headphones, a marked-up dance floor, two types of music, and memory targets (sash colors and symbols). In each trial, 10 dancers wore radio headphones and one of four different colored sashes, half of which carried cat symbols. Using silent-disco technology, one type of music was surreptitiously transmitted to half the dancers, while music at a different tempo was transmitted to the remaining dancers. Pre-experiment, the dancers' faces were photographed. Post-experiment, each dancer was presented with the photographs of the other dancers and asked to recall their memory targets. Results showed that same-music dancing significantly enhanced memory for sash color and sash symbol. Our findings are discussed in light of recent eye-movement research that showed significantly increased gaze durations for people observing music-dance synchrony versus music-dance asynchrony, and in relation to current literature on interpersonal entrainment, group cohesion, and social bonding

Clinical handover within the emergency care pathway and the potential risks of clinical handover failure (ECHO) : primary research

Background and objectives: Handover and communication failures are a recognised threat to patient safety. Handover in emergency care is a particularly vulnerable activity owing to the high-risk context and overcrowded conditions. In addition, handover frequently takes place across the boundaries of organisations that have different goals and motivations, and that exhibit different local cultures and behaviours. This study aimed to explore the risks associated with handover failure in the emergency care pathway, and to identify organisational factors that impact on the quality of handover. Methods: Three NHS emergency care pathways were studied. The study used a qualitative design. Risks were explored in nine focus group-based risk analysis sessions using failure mode and effects analysis (FMEA). A total of 270 handovers between ambulance and the emergency department (ED), and the ED and acute medicine were audio-recorded, transcribed and analysed using conversation analysis. Organisational factors were explored through thematic analysis of semistructured interviews with a purposive convenience sample of 39 staff across the three pathways. Results: Handover can serve different functions, such as management of capacity and demand, transfer of responsibility and delegation of aspects of care, communication of different types of information, and the prioritisation of patients or highlighting of specific aspects of their care. Many of the identified handover failure modes are linked causally to capacity and patient flow issues. Across the sites, resuscitation handovers lasted between 38 seconds and 4 minutes, handovers for patients with major injuries lasted between 30 seconds and 6 minutes, and referrals to acute medicine lasted between 1 minute and approximately 7 minutes. Only between 1.5% and 5% of handover communication content related to the communication of social issues. Interview participants described a range of tensions inherent in handover that require dynamic trade-offs. These are related to documentation, the verbal communication, the transfer of responsibility and the different goals and motivations that a handover may serve. Participants also described the management of flow of patients and of information across organisational boundaries as one of the most important factors influencing the quality of handover. This includes management of patient flows in and out of departments, the influence of time-related performance targets, and the collaboration between organisations and departments. The two themes are related. The management of patient flow influences the way trade-offs around inner tensions are made, and, on the other hand, one of the goals of handover is ensuring adequate management of patient flows. Conclusions: The research findings suggest that handover should be understood as a sociotechnical activity embedded in clinical and organisational practice. Capacity, patient flow and national targets, and the quality of handover are intricately related, and should be addressed together. Improvement efforts should focus on providing practitioners with flexibility to make trade-offs in order to resolve tensions inherent in handover. Collaborative holistic system analysis and greater cultural awareness and collaboration across organisations should be pursued