Anton Kruger - Academia.edu (original) (raw)

Papers by Anton Kruger

Data Time Series and geospatial, in situ and remotely sensed, physical, chemical and biological h... more Data Time Series and geospatial, in situ and remotely sensed, physical, chemical and biological hydrologic data sets Information Synthesis Data synthesis and standardization, prototype system development, hypothesis testing Information Technology Improved data storage, access, visualization and modeling tools One way to think about the mission of CUAHSI HIS is illustrated in Figure 1, which presents the CUAHSI Information Systems program as having four areas of emphasis: ideas, data, information technology, and information synthesis. Th e ideas area of emphasis comprises the intellectual insights, mathematical formulations, and motivations for research that animate the CUAHSI Science Plan and the work of individual hydrologic science investigators. Th e data area of emphasis encompasses all the bodies of data that are needed to conduct a particular investigation, whether obtained at the CUAHSI Hydrologic Observatories, by individual experiments, by hydrologic monitoring programs, or by remote sensing. Th e information technology area of emphasis encompasses the tools that are needed to assimilate, interpret, analyze, and visualize the data. Th e information synthesis area of emphasis is where the ideas, data, and technology are brought together to achieve new insights and scientifi c advances. Activity Y1 Y2 Y3 Y4 Y5 Y6

We propose an innovative meteorological radar, which uses reduced number of spatiotemporal sample... more We propose an innovative meteorological radar, which uses reduced number of spatiotemporal samples without compromising the accuracy of target information. Our approach extends recent research on compressed sensing (CS) for radar remote sensing of hard point scatterers to volumetric targets. The previously published CS-based radar techniques are not applicable for sampling weather since the precipitation echoes lack sparsity in both range-time and Doppler domains. We propose an alternative approach by adopting the latest advances in matrix completion algorithms to demonstrate the sparse sensing of weather echoes. We use Iowa X-band Polarimetric (XPOL) radar data to test and illustrate our algorithms.

$Research paper thumbnail of Precise Semidefinite Programming Formulation of Atomic Norm Minimization for Recovering d-Dimensional ($d\geq 2$) Off-the-Grid Frequencies$

arXiv (Cornell University), Dec 2, 2013

Recent research in off-the-grid compressed sensing (CS) has demonstrated that, under certain cond... more Recent research in off-the-grid compressed sensing (CS) has demonstrated that, under certain conditions, one can successfully recover a spectrally sparse signal from a few time-domain samples even though the dictionary is continuous. In particular, atomic norm minimization was proposed in [1] to recover 1-dimensional spectrally sparse signal. However, in spite of existing research efforts [2], it was still an open problem how to formulate an equivalent positive semidefinite program for atomic norm minimization in recovering signals with d-dimensional (d ≥ 2) off-the-grid frequencies. In this paper, we settle this problem by proposing equivalent semidefinite programming formulations of atomic norm minimization to recover signals with d-dimensional (d ≥ 2) off-the-grid frequencies.

Journal of the Atmospheric Sciences, 1999

In recent studies it is shown that in variable rain the spatial distribution of drops is not Pois... more In recent studies it is shown that in variable rain the spatial distribution of drops is not Poissonian. However, these past studies were limited to 1-min drop counts, which likely correspond to spatial scales of a few hundred to several hundreds of meters. In this work results based on 1-s drop counts using a video disdrometer are reported. It is shown that the clustering of raindrops previously found during intervals of 1 min also occurs during 1 s as well in convective rain. These latter temporal scales likely correspond to spatial features having dimensions from only a few to tens of meters. Combined with the authors' earlier results, these findings suggest that clustering of raindrops and meteorological variability span the range of scales from at least as small as a few meters to several hundreds of meters in convective precipitating systems. Consequently, non-Poissonian clustering reported in previous work (analyzing data accumulated over hours using 1-min drop counts) cannot be dismissed as artifacts in the data or errors in the processing. These studies appear to reflect accurately the true probabilistic character of rainfall. Moreover, it is shown that the clustering is more prevalent and occurs over longer coherence times for larger than for smaller drops. An argument is given suggesting that the clustering of larger drops is likely associated with the larger scales of convection, whereas the clustering of smaller drops is likely more strongly influenced by smaller-scale turbulence. Furthermore, in convective rain it appears that the coherence times of drop size distributions will often be governed by the smaller drops. Using current technology, this will make it very difficult, at times, to adequately sample the larger drops in variable rain without mixing observations from more than one drop size distribution at the smaller sizes. Nevertheless, care must be taken since oversampling destroys information just as effectively as undersampling misses it.

2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021

In the summers of 2018 and 2019, a 433 MHz radio link was installed in an Iowa corn field, intend... more In the summers of 2018 and 2019, a 433 MHz radio link was installed in an Iowa corn field, intended to measure the vegetation's water content. A set of three transmitters within the canopy emitted microwave radiation omnidirectionally in succession to each other, while the receiver, also within the corn canopy, listened continuously. The system was in operation for 68 days in 2018, beginning when the corn was only 0.3 m tall and ending in a full canopy environment. An increasing vegetation water content corresponded to an increasing canopy dielectric constant and thus a lower canopy transmissivity. A weakened signal received was for the most part attributed to electric field attenuation. In 2019, antennas remained in the field through October, observing the dry-down senescence as an increasing signal strength. The magnitude of air - soil reflection is another strong factor on received signal strength, as for all transmitter - receiver pairs the direct and ground - reflected signal destructively interfered. Radiative transfer models of the system often simulate the received signal to be stronger than observed. Neglecting scattering may be the cause of this error. Utilizing the software Signals of Opportunity Coherent Bistatic Scattering Simulator (SCoBi) may produce a more accurate calculation of power received.

Journal of Hydrometeorology, 2016

This article presents the data collected and analyzed using the University of Iowa’s X-band polar... more This article presents the data collected and analyzed using the University of Iowa’s X-band polarimetric (XPOL) radars that were part of the spring 2013 hydrology-oriented Iowa Flood Studies (IFloodS) field campaign, sponsored by NASA’s Global Precipitation Measurement (GPM) Ground Validation (GV) program. The four mobile radars have full scanning capabilities that provide quantitative estimation of the rainfall at high temporal and spatial resolutions over experimental watersheds. IFloodS was the first extensive test of the XPOL radars, and the XPOL radars demonstrated their field worthiness during this campaign with 46 days of nearly uninterrupted, remotely monitored, and controlled operations. This paper presents detailed postcampaign analyses of the high-resolution, research-quality data that the XPOL radars collected. The XPOL dual-polarimetric products and rainfall are compared with data from other instruments for selected diverse meteorological events at high spatiotemporal r...

Researchers are working on using freshwater mussels as biological sensors. A sensor placed on the... more Researchers are working on using freshwater mussels as biological sensors. A sensor placed on the mussel detects the mussel's rhythmic opening and closing, or gape. Changes in the gape can indicate changes in the mussel's environment. We plan to attach gape sensors, microcontrollers, and radios to mussels and place them back in their natural environment. Small, inexpensive radios operating in the Industrial, Scientific and Medical (ISM) bands will provide the physical link of an underwater wireless sensor network (WSN). Despite the attenuation radio waves experience in water, the low cost of these radios should allow us to deploy enough to set up a reliable communications network. While commercially available radios can be used underwater with waterproofing, antennas designed for use in air are unsuitable for use in water, because of the different electromagnetic properties of water and air. We designed dipole, loop, and folded dipole antennas for use in water and attached these to transmitters. We measured the power transmitted by the antennas by immersing the transmitters in a tank of water and measuring the received power at different distances using a small dipole antenna attached to a spectrum analyzer. The distance between the antennas was precisely controlled with a motorized xy positioner.

IEEE Access, 2016

We have developed a robust sensor for mounting on bridges over rivers and streams. These bridge-m... more We have developed a robust sensor for mounting on bridges over rivers and streams. These bridge-mounted river stage sensors (BMRSS) make periodic measurements of the distance from the sensor to the water level below. Properly interpreted, these measurements provide river-stage information, data of great importance to society and crucial to effective flood forecasting. The traditional approach to river stage measurement is the installation of pipes in rivers, digging stilling wells, and the construction of attendant brick-and-mortar infrastructure. The cost of this approach limits the deployment to larger rivers. In most instances, river-stage data from smaller tributaries are few, even though such data can greatly enhance the quality of flood-forecasting models' outputs. In contrast, BMRSS units are an order of magnitude less expensive and allow for widespread deployment. BMRSS units incorporate an ultrasonic distancemeasuring module, a solar panel/battery/charge controller, and a GPS receiver. In recent years, the Internet access through commercial cellular networks has become ubiquitous, even in most rural areas. BMRSS units incorporate cell modems and transmit data through the Internet to servers at the Iowa Flood Center. Here, the data are ingested into relational databases and made available to flood forecasting models and information systems. We have deployed and operated more than 220 BMRSS units across Iowa, many for several years continuously. INDEX TERMS Sensor systems and applications, cellular networks, hazards, instrumentation and measurement.

MILCOM 2016 - 2016 IEEE Military Communications Conference, 2016

We report on recent results from our ongoing work on demonstrating retrodirective transmission fr... more We report on recent results from our ongoing work on demonstrating retrodirective transmission from distributed arrays. Specifically, we describe a successful experimental demonstration of retrodirective beamforming to a non-cooperating receiver from an array of three distributed transceivers using (mostly) off-the-shelf hardware and simple and standard signal processing techniques. We build on our recently reported work that describes a synchronization procedure that allows the array nodes to estimate and compensate for the combined effects of frequency offsets and drifts in the oscillators as well as nonreciprocal elements in the transceiver hardware. We show how the array nodes that have performed the above synchronization process can then use an opportunistic incoming transmission from an external target to perform retrodirective beamforming back to that target without any coordination with that target. Our experimental results show beamforming gains greater than 90%. A key distinguishing feature of our work is that our procedure requires no wired links between the array nodes, no GPS, nor any other shared signal. To the best of our knowledge, this is the first ever demonstration of retrodirective beamforming from a fully wireless distributed array.

For water resource managers, ensemble streamflow predictions represent one of the most significan... more For water resource managers, ensemble streamflow predictions represent one of the most significant products of the National Weather Service’s (NWS) Advanced Hydrologic Prediction Services (AHPS). This project seeks to advance a distributions-oriented (DO) framework for verification of probability distribution forecasts derived from ensemble streamflow predictions. DO forecast quality measures provide a consistent diagnostic framework to quantify the relative sources of forecast skill, which would allow water managers to match decision tools to forecast attributes, and enable forecasters to target research, resources, and development efforts to the most valuable improvements. Expected outcomes from this research include: (1) a consistent framework for verifying probability distribution forecasts, which will be demonstrated through the evaluation and comparison of forecast quality of 6-90 day NWS AHPS ensemble streamflow forecasts for the North-Central and Ohio River Forecast Centers, and (2) a set of diagnostic verification tools for elucidating relevant forecast quality attributes, for the management and targeted improvement of forecasts systems, and interpretation of forecasts for their operational use.

Measuring and estimating rainfall accurately continues to be a significant challenge. While rainf... more Measuring and estimating rainfall accurately continues to be a significant challenge. While rainfall is arguably the most dynamic water flux, thus crucial for predictive hydrologic models, monitoring its spatial and temporal variability is subject to observational difficulties. The authors discuss field activities focused on providing accurate data for validation studies of remote sensing based rainfall estimates. The activities include three

IEEE Geoscience and Remote Sensing Letters, 2011

Page 1. 346 IEEE GEOSCIENCE AND REMOTE SENSING LETTERS, VOL. 8, NO. 2, MARCH 2011 Using Cellular ... more Page 1. 346 IEEE GEOSCIENCE AND REMOTE SENSING LETTERS, VOL. 8, NO. 2, MARCH 2011 Using Cellular Network Signal Strength to Monitor Vegetation Characteristics Kenneth P. Hunt, Student Member, IEEE, James ...

Over the last decade, pulse compression (PC) processing has proven to be critical in improving th... more Over the last decade, pulse compression (PC) processing has proven to be critical in improving the sensitivity of weather radars. This is largely because PC decouples the dependence of pulse length on range resolution, thereby allowing considerably higher resolution and sensitivity. Advances in PC-based weather radar waveform design have been complemented by the increasing use of solid-state transmitters in long-range weather radars. These systems have lower peak power and higher duty cycle, which makes PC implementation in hardware feasible.