Filtering by
- All Subjects: engineering
While attempting to provide real world experiences in STEM, educators face numerous challenges including adhering to curriculum requirements and working with potentially limited resources. The purpose of this action research study was to examine how the addition of authentic learning modules to the existing University of Arizona Middle School Engineering 101 (UA MS engineering 101) unit on energy efficiency can provide students with real world experiences as active participants. During an instructional workshop, participating teachers were introduced to strategies they use in their classroom so students could engage with individuals from both inside and outside of the school to create solutions for energy issues the students have identified within their own schools. This study used a series of observations, interviews, and focus groups with the teacher participants to gather data in determining how and in what ways students were able to obtain real world experiences as active participants through the authentic learning modules. Because there are numerous teachers within the UA MS engineering 101 group, a future goal was to assist these additional teachers in providing this innovation to their students.
Alloying selenium into ReS2 in the creation of ReS2xSe2-x, tunes the band gap and changes its vibrational spectrum. Depositing this alloy using bottom up approach has resulted in the loss of crystallinity. This loss of crystallinity was evidenced by grain boundaries and point defect shown by TEM images.
Also, in the creation of TiS3xSe3-x, by alloying Se into TiS3, a fixed ratio of 8% selenium deposit into TiS3 host matrix is observed. This is despite the vastly differing precursor amounts and growth temperatures, as evinced by detailed TEM, EDAX, TEM diffraction, and Raman spectroscopy measurements. This unusual behavior contrasts with other well-known layered material systems such as MoSSe, WMoS2 where continuous alloying can be attained. Cluster expansion theory calculations suggest that only limited composition (x) can be achieved. Considering the fact that TiSe3 vdW crystals have not been synthesized in the past, these alloying rejections can be attributed to energetic instability in the ternary phase diagrams estimated by calculations performed. Overall findings highlight potential means and challenges in achieving stable alloying in promising direct gap and high carrier mobility TiS3 materials.
The pads were created using varying amounts of LM and matrix materials ranging from copper microspheres to diamond powder mixed into PDMS using a high-speed mixer. The material was then cast into molds and cured to create the pads. Once the pads were created, the difficulty came in quantifying their thermal properties. A stepped bar apparatus (SBA) following ASTM D5470 was created to measure the thermal resistance of the pads but it was determined that thermal conductivity was a more usable metric of the pads’ performance. This meant that the pad’s in-situ thickness was needed during testing, prompting the installation of a linear encoder to measure the thickness. The design and analysis of the necessary modification and proposed future design is further detailed in the following paper.
Robert (Bob) Barnhill came to ASU in 1986 as Chair of the Computer Science Department and left in 1997 as the Vice President for Research. The interview addresses a number of topics including the beginnings of Computer Graphics, moving the Computer Science Department to a more research-oriented effort, achieving Research 1 status, working with the University of Arizona to develop a new statewide Intellectual Property template, dodging the Unabomber and playing soccer. Common themes throughout the interview include Bob’s success at getting groups of people to actually do something other than just meet and the importance of a strategic plan.
The purpose of this project was to develop a system capable of launching projectiles at a curved trajectory. This system effectively imparts spin on projectiles, enabling controlled indirect fire for the intended use of military operations. Through this proof of concept, it was determined whether a scaled system would be a viable solution to the issue of controlled indirect fire in dense urban areas. Using a series of coaxial motors with independently controlled speeds, it was possible to alter the horizontal and vertical displacement of objects in flight.
This paper examines the annual Energy Use Intensity (EUI) of 28 different K-12 schools within the Phoenix Metropolitan Region of Arizona over the span of five years and presents an analysis of changes in energy performance resulting from the measurement of energy use in K-12 schools. This paper also analyzes the patterns of change in energy use over time and provides a comparison of these patterns by school district.
An analysis of the energy performance data for the selected schools revealed a significant positive impact on the ability for schools to improve their energy performance through ongoing performance measurement. However, while schools tend to be able to make energy improvements through the implementation of energy measurement and performance tracking, deviation may exist in their ability to maintain ongoing energy performance over time. The results suggest that implementation of ongoing measurement is likely to produce positive impacts on the energy performance of schools, however further research is recommended to enhance and refine these results.
all the sensors in the network achieve global agreement using only local transmissions. In this dissertation, several consensus and consensus-based algorithms in WSNs are studied.
Firstly, a distributed consensus algorithm for estimating the maximum and minimum value of the initial measurements in a sensor network in the presence of communication noise is proposed. In the proposed algorithm, a soft-max approximation together with a non-linear average consensus algorithm is used. A design parameter controls the trade-off between the soft-max error and convergence speed. An analysis of this trade-off gives guidelines towards how to choose the design parameter for the max estimate. It is also shown that if some prior knowledge of the initial measurements is available, the consensus process can be accelerated.
Secondly, a distributed system size estimation algorithm is proposed. The proposed algorithm is based on distributed average consensus and L2 norm estimation. Different sources of error are explicitly discussed, and the distribution of the final estimate is derived. The CRBs for system size estimator with average and max consensus strategies are also considered, and different consensus based system size estimation approaches are compared.
Then, a consensus-based network center and radius estimation algorithm is described. The center localization problem is formulated as a convex optimization problem with a summation form by using soft-max approximation with exponential functions. Distributed optimization methods such as stochastic gradient descent and diffusion adaptation are used to estimate the center. Then, max consensus is used to compute the radius of the network area.
Finally, two average consensus based distributed estimation algorithms are introduced: distributed degree distribution estimation algorithm and algorithm for tracking the dynamics of the desired parameter. Simulation results for all proposed algorithms are provided.