708 research outputs found
Examining the relationship between student performance and video interactions
In this work, we attempted to predict student performance on a suite of
laboratory assessments using students' interactions with associated
instructional videos. The students' performance is measured by a graded
presentation for each of four laboratory presentations in an introductory
mechanics course. Each lab assessment was associated with between one and three
videos of instructional content. Using video clickstream data, we define
summary features (number of pauses, seeks) and contextual information (fraction
of time played, in-semester order). These features serve as inputs to a
logistic regression (LR) model that aims to predict student performance on the
laboratory assessments. Our findings show that LR models are unable to predict
student performance. Adding contextual information did not change the model
performance. We compare our findings to findings from other studies and explore
caveats to the null-result such as representation of the features, the
possibility of underfitting, and the complexity of the assessment.Comment: 4 pages, 1 figure, submitted to the PERC 2018 proceeding
The Birth of a Watershed Alliance in the San Pedro Basin of the U.S.- Mexico Border Region [abstract]
2 pages
The Birth of a Watershed Alliance in the San Pedro Basin of the U.S.- Mexico Border Region [abstract]
2 pages
Helicopter mathematical models and control law development for handling qualities research
Progress made in joint NASA/Army research concerning rotorcraft flight-dynamics modeling, design methodologies for rotorcraft flight-control laws, and rotorcraft parameter identification is reviewed. Research into these interactive disciplines is needed to develop the analytical tools necessary to conduct flying qualities investigations using both the ground-based and in-flight simulators, and to permit an efficient means of performing flight test evaluation of rotorcraft flying qualities for specification compliance. The need for the research is particularly acute for rotorcraft because of their mathematical complexity, high order dynamic characteristics, and demanding mission requirements. The research in rotorcraft flight-dynamics modeling is pursued along two general directions: generic nonlinear models and nonlinear models for specific rotorcraft. In addition, linear models are generated that extend their utilization from 1-g flight to high-g maneuvers and expand their frequency range of validity for the design analysis of high-gain flight control systems. A variety of methods ranging from classical frequency-domain approaches to modern time-domain control methodology that are used in the design of rotorcraft flight control laws is reviewed. Also reviewed is a study conducted to investigate the design details associated with high-gain, digital flight control systems for combat rotorcraft. Parameter identification techniques developed for rotorcraft applications are reviewed
Rotorcraft handling-qualities design criteria development
Joint NASA/Army efforts at the Ames Research Center to develop rotorcraft handling-qualities design criteria began in earnest in 1975. Notable results were the UH-1H VSTOLAND variable stability helicopter, the VFA-2 camera-and-terrain-board simulator visual system, and the generic helicopter real-time mathematical model, ARMCOP. An initial series of handling-qualities studies was conducted to assess the effects of rotor design parameters, interaxis coupling, and various levels of stability and control augmentation. The ability to conduct in-flight handling-qualities research was enhanced by the development of the NASA/Army CH-47 variable-stability helicopter. Research programs conducted using this vehicle include vertical-response investigations, hover augmentation systems, and the effects of control-force characteristics. The handling-qualities data base was judged to be sufficient to allow an update of the military helicopter handling-qualities specification, MIL-H-8501. These efforts, including not only the in-house experimental work but also contracted research and collaborative programs performed under the auspices of various international agreements. The report concludes by reviewing the topics that are currently most in need of work, and the plans for addressing these topics
Using e-collaboration to improve management education: three scenarios
This paper explores the potential impact of collaborative technologies in improving management education. The first goal is to expose students to tools and practices that not only assist them with their current studies, but also serve to reinforce individual and team competencies that can facilitate their entry into the workforce. In their positions as future managers they will be expected to not only be familiar with common business practices but also to understand the implications of information technology for business; in this case with emphasis on tools and techniques that can help businesses flourish in the networked economy. With an ever-increasing recognition that e-learning tools are important for (re-)training employees, these three scenarios offer examples of how business schools might expand the boundaries of e-collaboration to help their students. These experiments have been conducted in management programs. In the first two scenarios, students use collaborative platforms in some of their daily work. The third experiment is based on a student-centred design of a learning portal. Our experience reinforces a certain number of hypotheses influencing the impact of collaborative technologies in management education. To begin with, information systems are often flawed mirrors of the managerial system that they are designed to represent. Secondly, the potential value of collaborative technologies is strongly influenced by organizational contexts, both in and between the university and the business community. Thirdly, the effectiveness of collaborative technologies depends to a large degree upon the depth and coherence of learning objectives fixed for learning and work places. Finally, improving the effectiveness of collaborative technologies requires aligning the design of learning environments with the corporate cultures and visions we are trying to reproduce
An integrated Rotorcraft Avionics/Controls Architecture to support advanced controls and low-altitude guidance flight research
Salient design features of a new NASA/Army research rotorcraft--the Rotorcraft-Aircrew Systems Concepts Airborne Laboratory (RASCAL) are described. Using a UH-60A Black Hawk helicopter as a baseline vehicle, the RASCAL will be a flying laboratory capable of supporting the research requirements of major NASA and Army guidance, control, and display research programs. The paper describes the research facility requirements of these programs together with other critical constraints on the design of the research system. Research program schedules demand a phased development approach, wherein specific research capability milestones are met and flight research projects are flown throughout the complete development cycle of the RASCAL. This development approach is summarized, and selected features of the research system are described. The research system includes a real-time obstacle detection and avoidance system which will generate low-altitude guidance commands to the pilot on a wide field-of-view, color helmet-mounted display and a full-authority, programmable, fault-tolerant/fail-safe, fly-by-wire flight control system
Alternative model for the administration and analysis of research-based assessments
Research-based assessments represent a valuable tool for both instructors and
researchers interested in improving undergraduate physics education. However,
the historical model for disseminating and propagating conceptual and
attitudinal assessments developed by the physics education research (PER)
community has not resulted in widespread adoption of these assessments within
the broader community of physics instructors. Within this historical model,
assessment developers create high quality, validated assessments, make them
available for a wide range of instructors to use, and provide minimal (if any)
support to assist with administration or analysis of the results. Here, we
present and discuss an alternative model for assessment dissemination, which is
characterized by centralized data collection and analysis. This model provides
a greater degree of support for both researchers and instructors in order to
more explicitly support adoption of research-based assessments. Specifically,
we describe our experiences developing a centralized, automated system for an
attitudinal assessment we previously created to examine students'
epistemologies and expectations about experimental physics. This system
provides a proof-of-concept that we use to discuss the advantages associated
with centralized administration and data collection for research-based
assessments in PER. We also discuss the challenges that we encountered while
developing, maintaining, and automating this system. Ultimately, we argue that
centralized administration and data collection for standardized assessments is
a viable and potentially advantageous alternative to the default model
characterized by decentralized administration and analysis. Moreover, with the
help of online administration and automation, this model can support the
long-term sustainability of centralized assessment systems.Comment: 7 pages, 1 figure, accepted in Phys. Rev. PE
Removal of terrestrial DOC in aquatic ecosystems of a temperate river network
Surface waters play a potentially important role in the global carbon balance. Dissolved organic carbon (DOC) fluxes are a major transfer of terrestrial carbon to river systems, and the fate of DOC in aquatic systems is poorly constrained. We used a unique combination of spatially distributed sampling of three DOC fractions throughout a river network and modeling to quantify the net removal of terrestrial DOC during a summer base flow period. We found that aquatic reactivity of terrestrial DOC leading to net loss is low, closer to conservative chloride than to reactive nitrogen. Net removal occurred mainly from the hydrophobic organic acid fraction, while hydrophilic and transphilic acids showed no net change, indicating that partitioning of bulk DOC into different fractions is critical for understanding terrestrial DOC removal. These findings suggest that river systems may have only a modest ability to alter the amounts of terrestrial DOC delivered to coastal zones
Dimensions of Internet Commerce Trust
Trust is a central construct and plays a critical role in understanding Internet consumer behavior. This research seeks to directly address the subject of Internet Commerce Trust (ICT) by developing a valid, reliable, and generalizable scale to measure this multifaceted subject. Two separate studies reveal a common five-factor structure. These dimensions are labeled (1) Certification, (2) Resources and Capabilities, (3) Shopping Method, (4) Reliability, and (5) Communication Viability. An accurate measurement of ICT will serve as a viable control factor in future studies of Internet consumer behaviors, segmentation analyses, and in marketing strategy research
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