This paper addresses various aspects of optimal phasor measurement unit (PMU) placement problem. We propose a procedure for multistaging of PMU placement in a given time horizon using an integer ...linear programming (ILP) framework. Hitherto, modeling of zero injection constraints had been a challenge due to the intrinsic nonlinearity associated with it. We show that zero injection constraints can also be modeled as linear constraints in an ILP framework. Minimum PMU placement problem has multiple solutions. We propose two indices, viz, BOI and SORI, to further rank these multiple solutions, where BOI is bus observability index giving a measure of number of PMUs observing a given bus and SORI is system observability redundancy index giving sum of all BOI for a system. Results on IEEE 118 bus system have been presented. Results indicate that: (1) optimal phasing of PMUs can be computed efficiently; (2) proposed method of modeling zero injection constraints improve computational performance; and (3) BOI and SORI help in improving the quality of PMU placement.
Classroom Assessment and Educational Measurement explores the ways in which the theory and practice of both educational measurement and the assessment of student learning in classroom settings ...mutually inform one another. Chapters by assessment and measurement experts consider the nature of classroom assessment information, from student achievement to affective and socio-emotional attributes; how teachers interpret and work with assessment results; and emerging issues in assessment such as digital technologies and diversity/inclusion. This book uniquely considers the limitations of applying large-scale educational measurement theory to classroom assessment and the adaptations necessary to make this transfer useful. Researchers, graduate students, industry professionals, and policymakers will come away with an essential understanding of how the classroom assessment context is essential to broadening contemporary educational measurement perspectives.
The importance of fairness, validity, and accessibility in assessment is greater than ever as testing expands to include more diverse populations, more complex purposes, and more sophisticated ...technologies. This book offers a detailed account of fairness in assessment, and illustrates the interplay between assessment and broader changes in education. In 16 chapters written by leading experts, this volume explores the philosophical, technical, and practical questions surrounding fair measurement. Fairness in Educational Assessment and Measurement addresses issues pertaining to the construction, administration, and scoring of tests, the comparison of performance across test takers, grade levels and tests, and the uses of educational test scores. Perfect for researchers and professionals in test development, design, and administration, Fairness in Educational Assessment and Measurement presents a diverse array of perspectives on this topic of enduring interest.
This contribution focuses on the nondestructive evaluation of the thickness of metallic plates, by means of eddy-current testing. Specifically, we present a method for reducing/optimizing the ...measurement time for the approach presented in (Yin and Peyton, 2007), while keeping a high accuracy suitable for industrial applications. In (Yin and Peyton, 2007), the key feature for estimating the thickness of plates is the value of the frequency where a proper quantity achieves its minimum value. To get a proper accuracy in measuring the thickness of the plate, this minimum needs to be located in an accurate manner. In turns, this requires "many" measurements at different frequencies, which make the approach time-consuming and not suitable for almost real-time applications, as those of interest for industry. The proposed patent pending strategy combines a multisine approach to collect the data onto a proper set of frequencies, plus proper techniques for interpolating the data at all the frequencies required to locate accurately the minimum of the response. The combination of the multisine to allocate efficiently the measurement frequencies with the data interpolation results in a reduction of the number of required measurements and, in ultimate analysis, of the overall measurement time. Specifically, the measurement time for a typical situation was reduced of a factor of about 4 (from 13 to 2.66 s) with the same accuracy level of the order of 3%. Finally, we highlight that both design and testing of the new measurement method were carried out by combining numerical simulations and experimental results.
The ever-growing complexity of radiating systems asks for always more challenging radiation pattern characterizations requiring time consuming field acquisitions and high-cost facilities. ...Consequently phaseless, or magnitude-only, measurements have recently regained of interest as they prevent the tedious and difficult task of phase acquisition. Consequently, it allows the use of cheaper or more versatile measurement setups like drone measurements or easier high-frequency measurements. However, the difficulty is shifted to the notoriously difficult resolution of the phase retrieval problem, which instability is commonly mitigated by the acquisition of a large number of phaseless field samples. A procedure enabling a reliable and accurate phaseless antenna measurement from a reduced number of spherical NF samples based on the two scan technique is proposed. Its efficiency and stability, that relies on the systematic determination of a good starting point, is validated by representative simulations and experimental cases performed on various antenna structures.
On the Estimation of Angle Rate in Radar Nanzer, Jeffrey A.; Sharp, Matthew D.
IEEE transactions on antennas and propagation,
2017-March, 2017-3-00, Letnik:
65, Številka:
3
Journal Article
Recenzirano
The direct measurement of the angle rate of moving objects using a radar with a spatially diverse electric field pattern, a measurement analogous to the measurement of the range rate of a moving ...objects, represents, along with the measurements of range, range rate, and angle, a fourth basic radar measurement. Recently introduced and experimentally demonstrated, the theoretical accuracy of the direct measurement of angle rate is derived in this paper, and it is compared to the measurements of range, range rate, and angle in the context of the optimal signal forms for the best measurement accuracy. Signal forms achieving optimal accuracy for each measurement are discussed; example implementations of high-accuracy measurements are compared to the optimal forms; and the limitations of simultaneous measurements of pairs of measurements are derived. Combining the angle rate measurement with the three other standard radar measurements may provide future radar systems the capability to simultaneously and instantaneously measure the position and 3-D trajectory of moving objects without compromising the accuracy of any individual measurement.
A free-space time-domain method is proposed to retrieve dielectric constant (<inline-formula> <tex-math notation="LaTeX">\varepsilon _{r} </tex-math></inline-formula>), conductivity (<inline-formula> ...<tex-math notation="LaTeX">\sigma _{e} </tex-math></inline-formula>), and thickness (<inline-formula> <tex-math notation="LaTeX">d </tex-math></inline-formula>) of metal-backed low-loss dielectric samples using calibration-independent reflected power peak measurements. Its algorithm is validated by numerical calculations and simulations (CST Microwave Studio) using a sine-modulated Gaussian window. A sensitivity analysis is followed to examine its performance considering the dependencies of reflected power peaks with respect to <inline-formula> <tex-math notation="LaTeX">\varepsilon _{r} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\sigma _{e} </tex-math></inline-formula>. Free-space time-domain measurements have been implemented after transforming frequency-domain measurements into time-domain ones to extract <inline-formula> <tex-math notation="LaTeX">\varepsilon _{r} </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">\sigma _{e} </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">d </tex-math></inline-formula> of polypropylene, polyethylene, and polyoxymethylene samples.
This paper introduces a notion of data informativity for stabilization tailored to continuous-time signals and systems. We establish results comparable to those known for discrete-time systems with ...sampled data. We justify that additional assumptions on the properties of the noise signals are needed to understand when sampled versions of continuous-time signals are informative for stabilization, thereby introducing the notions of square Lipschitzness and total bounded variation. This allows us to connect the continuous and discrete domains, yielding sufficient conditions to synthesize a stabilizing controller for the true continuous-time system on the basis of sampled data. Simulations illustrate our results.
Despite developments in research and practice on using examinee response process data in assessment design, the use of such data in test validation is rare. Validation of Score Meaning in the Next ...Generation of Assessments Using Response Processes highlights the importance of validity evidence based on response processes and provides guidance to measurement researchers and practitioners in creating and using such evidence as a regular part of the assessment validation process. Response processes refer to approaches and behaviors of examinees when they interpret assessment situations and formulate and generate solutions as revealed through verbalizations, eye movements, response times, or computer clicks. Such response process data can provide information about the extent to which items and tasks engage examinees in the intended ways. With contributions from the top researchers in the field of assessment, this volume includes chapters that focus on methodological issues and on applications across multiple contexts of assessment interpretation and use. In Part I of this book, contributors discuss the framing of validity as an evidence-based argument for the interpretation of the meaning of test scores, the specifics of different methods of response process data collection and analysis, and the use of response process data relative to issues of validation as highlighted in the joint standards on testing. In Part II, chapter authors offer examples that illustrate the use of response process data in assessment validation. These cases are provided specifically to address issues related to the analysis and interpretation of performance on assessments of complex cognition, assessments designed to inform classroom learning and instruction, and assessments intended for students with varying cultural and linguistic backgrounds.
Reconfigurable intelligent surfaces (RISs) provide an interface between the electromagnetic world of wireless propagation environments and the digital world of information science. Simple yet ...sufficiently accurate path loss models for RISs are an important basis for theoretical analysis and optimization of RIS-assisted wireless communication systems. In this paper, we refine our previously proposed free-space path loss model for RISs to make it simpler, more applicable, and easier to use. The impact of the antenna's directivity of the transmitter, receiver, and the unit cells of the RIS on the path loss is explicitly formulated as an angle-dependent loss factor. The refined model gives more accurate estimates of the path loss of RISs comprised of unit cells with a deep sub-wavelength size. Based on the proposed model, the properties of a single unit cell are evaluated in terms of scattering performance, power consumption, and area, which allows us to unveil fundamental considerations for deploying RISs in high frequency bands. Two fabricated RISs operating in the millimeter-wave (mmWave) band are utilized to carry out a measurement campaign. The measurement results are shown to be in good agreement with the proposed path loss model. In addition, the experimental results suggest an effective form to characterize the power radiation pattern of the unit cell for path loss modeling.
