Educators and researchers who study human learning often assume that feedback is most effective when given immediately. However, a growing body of research has challenged this assumption by demonstrating that delaying feedback can facilitate learning. Advocates for immediate feedback have questioned the generalizability of this finding, suggesting that such effects only occur in highly controlled laboratory settings. We report a pair of experiments in which the timing of feedback was manipulated in an upperlevel college engineering course. Students practiced applying their knowledge of complex engineering concepts on weekly homework assignments, and then received feedback either immediately after the assignment deadline or 1 week later. When students received delayed feedback, they performed better on subsequent course exams that contained new problems about the same concepts. Although delayed feedback produced superior transfer of knowledge, students reported that they benefited most from immediate feedback, revealing a metacognitive disconnect between actual and perceived effectiveness.

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We propose a scheme for bistatic radar that uses a chaotic system to generate a wideband FM signal that is reconstructed at the receiver via a conventional phase lock loop. The setup for the bistatic radar includes a 3 state variable drive oscillator at the transmitter and a response oscillator at the receiver. The challenge is in synchronizing the response oscillator of the radar receiver utilizing a scaled version of the transmitted signal s r (t, x) = αs t (t, x) where x is one of three driver oscillator state variables and α is the scaling factor that accounts for antenna gain, system losses, and space propagation. For FM, we also assume that the instantaneous frequency of the received signal, x s , is a scaled version of the Lorenz variable x. Since this additional scaling factor may not be known a priori, the response oscillator must be able to accept the scaled version of x as an input. Thus, to achieve synchronization we utilize a generalized projective synchronization technique that introduces a controller term -μe where μ is a control factor and e is the difference between the response state variable x s and a scaled x. Since demodulation of s r (t) is required to reconstruct the chaotic state variable x, the phase lock loop imposes a limit on the minimum error e. We verify through simulations that, once synchronization is achieved, the short-time correlation of x and x s is high and that the self-noise in the correlation is negligible over long periods of time.

Characterization measurements of wideband antennas can be a time intensive and an expensive process as many data points are required in both the angular and frequency dimensions. Parallel compressive sensing is proposed to reconstruct the radiation-frequency patterns (RFP) of antennas from a sparse and random set of measurements. The modeled RFP of the dual-ridge horn, bicone, and Vivaldi antennas are used to analyze the minimum number of measurements needed for reconstruction, the difference in uniform versus non-uniform reconstruction, and the sparsity transform function used in the compressive sensing algorithm. The effect of additive white Gaussian noise (AWGN) on the minimum number of data points required for reconstruction is also studied. In a noise-free environment, the RFP of the antennas were adequately reconstructed using as little as 33% of the original data points. It was found that the RFPs were adequately reconstructed with less data points when the discrete cosine transforms (DCT), rather than the discrete Fourier transforms (DFT) was used in the compressive sensing algorithm. The presence of noise increases the number of data points required to reconstruct an RFP to a specified error tolerance, but the antenna RFPs can be reconstructed to within 1% root-mean-square-error of the original with a signal to noise ratio as low as −15 dB. The use of compressive sensing can thus lead to a new measurement methodology whereby a small subset of the total angular and frequency measurements is taken at random, and a full reconstruction of radiation and frequency behavior of the antenna is achieved during post-processing.

An Experiment to enhance Signals and Systems learning by using technology based teaching strategiesThe University of Texas at El Paso teamed with the "Signal Processing Education Network," (SPEN), which consists of academic, industry and professional community. SPEN, an NSFsponsored effort, is based on four technologies: Connexions, interactive simulation tools, Quadbase question/answer system and OpenStax Tutor. It seeks to develop materials that allow educators to break away from traditional textbook-lecture-homework education, and create a new framework based on an engaged community of educators, students, and industry professionals that continuously collaborate, improve and explore interactive content. The initial effort focuses on one strategic subdiscipline in electrical engineering, signal processing, but the framework can be applied to engineering education at all levels: high school, university (undergraduate and graduate) as well as continuing education.During the Fall 2012 and Spring 2013 semesters, UTEP implemented the use of Connexions, interactive examples, Quadbase system, and OpenStax Tutor in a sophomore course on Continuous-Time Signals and Systems. We organized existing material pertinent to the course into learning modules, created problems with associated solutions in Quadbase and developed interactive simulations in Mathematica to help students more effectively learn concepts with which they had difficulties. In addition, we used the assessment system provided by OpenStax Tutor to track and evaluate students' progress.OpenStax Tutor facilitates the instructors' work by automatically grading student work and exporting the grades to a spreadsheet. It also provides statistics of students' performance, e.g., reporting the time taken to complete specific assignments. These statistics enable assessment of overall class performance as the semester progresses.The feedback from students, gathered through a modified version of the SALG instrument, demonstrated that they enjoyed and learned the material better by using technology tools. The assessment of the learning gains of students in the Fall 2012 and Spring 2013 semester demonstrated an increase in the assessed learning outcomes compared to the Summer 2012 semester, where the tools were not used.The use of technology tools can address multiple situations in engineering education: limited opportunity for active learning; limited opportunity for laboratory activities that are interesting or relate to students' ideas about their "real world"; lack of interactive learning demos; textbooks providing limited connections among topics; development of textbooks and course materials limited to a small number of authors; and rising textbook costs that present a financial burden for students, especially low-income students.