- Award ID(s):
- 1725573
- PAR ID:
- 10201346
- Date Published:
- Journal Name:
- Econometric Theory
- ISSN:
- 0266-4666
- Page Range / eLocation ID:
- 1 to 36
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
This study employs a Data Envelopment Analysis (DEA) modeling technique to investigate the efficiency and productivity of renewable energy (RE) adoption across technologically diverse electricity-generating utilities. By employing metrics capturing policy effects, the study evaluates the RE adoption efficiency and productivity using a dynamic DEA model and the Malmquist DEA technique. First, the findings reveal that RE adoption is not significantly different across regional electricity markets. Second, the study revealed that RE adoption increased over the last three years. The total mean productivity change over the entire study period showed a mean improvement of 4.8%.more » « less
-
Abstract Hawkes models are frequently used to describe point processes that are clustered spatial‐temporally, and have been used in numerous applications including the study of earthquakes, invasive species, and contagious diseases. An extension of the Hawkes model is considered where the productivity is variable. In particular, the case is explored where each point may have its own productivity and a simple analytic formula is derived for the maximum likelihood estimators of these productivities. This estimator is compared with an empirical estimator and ways are explored of stabilizing both estimators by lower truncating, smoothing, and rescaling the estimates. Properties of the estimators are explored in simulations, and the methods are applied to seismological and epidemic datasets to show and quantify substantial variation in productivity.
-
Abstract Located at northern latitudes and subject to large seasonal temperature fluctuations, boreal forests are sensitive to the changing climate, with evidence for both increasing and decreasing productivity, depending upon conditions. Optical remote sensing of vegetation indices based on spectral reflectance offers a means of monitoring vegetation photosynthetic activity and provides a powerful tool for observing how boreal forests respond to changing environmental conditions. Reflectance‐based remotely sensed optical signals at northern latitude or high‐altitude regions are readily confounded by snow coverage, hampering applications of satellite‐based vegetation indices in tracking vegetation productivity at large scales. Unraveling the effects of snow can be challenging from satellite data, particularly when validation data are lacking. In this study, we established an experimental system in Alberta, Canada including six boreal tree species, both evergreen and deciduous, to evaluate the confounding effects of snow on three vegetation indices: the normalized difference vegetation index (NDVI), the photochemical reflectance index (PRI), and the chlorophyll/carotenoid index (CCI), all used in tracking vegetation productivity for boreal forests. Our results revealed substantial impacts of snow on canopy reflectance and vegetation indices, expressed as increased albedo, decreased NDVI values and increased PRI and CCI values. These effects varied among species and functional groups (evergreen and deciduous) and different vegetation indices were affected differently, indicating contradictory, confounding effects of snow on these indices. In addition to snow effects, we evaluated the contribution of deciduous trees to vegetation indices in mixed stands of evergreen and deciduous species, which contribute to the observed relationship between greenness‐based indices and ecosystem productivity of many evergreen‐dominated forests that contain a deciduous component. Our results demonstrate confounding and interacting effects of snow and vegetation type on vegetation indices and illustrate the importance of explicitly considering snow effects in any global‐scale photosynthesis monitoring efforts using remotely sensed vegetation indices.
-
Madden, John D. ; Anderson, Iain A. ; Shea, Herbert R. (Ed.)Wearable dielectric elastomer actuators (DEAs) have been greatly considered for development of biomedical devices. In particular, a DEA cuff device has the capability of minimizing venous system disorders that occur in the lower limbs such as orthostatic intolerance (OI) and deep-vein thrombosis which are a result of substantial blood pooling. Recent works have shown that DEAs could regulate and even enhance venous blood flow return. This wearable technology orders a new light, low-cost, compliant, and simple countermeasure which could be safely and comfortably worn that includes mobility. In addition, it may supplement or even provide an alternative solution to exercise and medication. This work presents the design, model, and characterization of the DEA cuff device design that is capable of generating significant pressure change. A rolled DEA strip was actuated over a simulated muscle-artery apparatus using a periodic voltage input, and fluid pressure change was directly observed. A force sensitive resistor sensor was used to achieve a more precise pressure measurement. Performance analysis was conducted through frequency response analysis. The results provide a framework for implementing dynamic modelling and control to allow various forms of actuation input.more » « less
-
Emrouznejad, A ; Thanassoulis, E ; Toloo, M (Ed.)Sponsored by the National Science Foundation, this article showcases the findings of a two-year study using Data Envelopment Analysis (DEA) with data from the Integrated Postsecondary Education Data System (IPEDS) at the National Center for Education Statistics, to effectively measure the efficiency of Hispanic Serving Institutions (HSIs) graduating Hispanics with STEM degrees. The guiding research question was: On what input measures do we select efficient HSIs to serve other HSI institutions as possible benchmarks for program improvement in graduating Hispanics with STEM degrees? An outcome of this work is a framework for investigating and organizing best practices at HSIs for increasing Hispanics earning STEM degrees. The project notably advances knowledge within the field of HSI research. Of the HSI studies published between 1978 and 2021, none used DEA and therefore, the proposed project has the potential to sprout a new branch of HSI research. The proposed project also has the potential to broadly impact desired American societal outcomes. Scientific literacy is one of the benefits from earning a STEM degree. Increasing Hispanics graduating with STEM degrees will here too, result in more voices that can purposefully engage in informed public discourse on science and technology policy, and especially on issues relevant to the Hispanic community.more » « less