David Arellano

Body-worn fully-passive wireless analog sensors for physiological signal capture through load modulation using resistive transducers

Fully-passive wireless body-sensors pose viable solutions for unobtrusive monitoring of physiological signals at natural settings. While fully-passive capacitive analog passive wireless sensors has been reported, we present an alternative solution with resistive based transducers. The passive sensor is composed of a loop antenna, a tuning capacitor, and a resistive transducer suitable for the type of physiological signals to be measured. The scanner transmits carrier RF signal at 13.75MHz whose amplitude is modulated based on the resistive loading by the transducer. The load modulation is captured with the signal analyzer. The system was characterized for various resistive loads of 1.2Ω to 82KΩ and open at 5, 10, 20, and 40 mm co-axial distances between the transmitter and the receiver antennas. We demonstrate the practicality of the system by measuring several physiological signals like heart rate, temperature, and pulse oximetry. The wireless power used for remote sensing is very low (-20dBm, except pulse oximetry requires 0dBm). The results show the potential of developing a new set of body-worn fully-passive sensors for physiological signal monitoring.

Guidelines for Geofoam Applications in Slope Stability Projects

.......................................................................................................................................... xxi EXECUTIVE SUMMARY ................................................................................................................... xxiii CHAPTER 1-BACKGROUND ........................................................................................................ 1-

Body-worn fully-passive wireless analog sensors for biopotential measurement through load modulation

Fully-passive wireless and disposable bodysensors are promising for unobtrusive monitoring of physiological signals at natural settings. We present a new type of wireless analog passive sensor (WAPS) based on resistive damping, which can be used for biopotential sensing. The resistive WAPS operates by modulating the amplitudes of the incident RF signal, and composes of a loop antenna, a tuning capacitor, and a MOSFET (an additional biasing resistance is used in one variation). The scanner transmits carrier RF signal at 13:34MHz and the load modulated signal is captured with the signal analyzer. The envelope of the modulated signal correlates with the biopotential being sensed. Both enhancement and depletion MOSFETs are demonstrated, where the earlier demonstrated superior performance. The sensitivity can be as low as 10 mV, suitable for ECG and EMG physiological signal capture. The transmission power were 0 dBm while the co-axial separation between antennas were 21.5 mm. The results show that the proposed WAPS can be used to develop disposable biopotential sensor suitable for body-worn physiological signal monitoring system.

Framework for Design Guideline for Expanded Polystyrene Block Geofoam in Slope Stabilization and Repair

This paper presents the framework for the interim design guideline for the use of expanded polystyrene (EPS) block geofoam for slope stabilization and repair, based on the findings of the NCHRP Project 24-11(02) Phase I study. The overall objective of this research is to develop a design guideline as well as an appropriate material and construction standard for the use of EPS block geofoam for the function of lightweight fill in slope stability applications. The recommended design methodology included in the framework is based on an assessment of the existing technology and literature. The Phase II work will refine the interim design guideline framework and address some uncertainties in the current state of the practice of analyzing various failure mechanisms included in the design procedure. The completed research will consist of the following five primary research products: (a) a summary of the relevant engineering properties, (b) a comprehensive design guideline, (c) a material and construction standard, (d) economic data, and (e) a detailed numerical example. No formal design guidelines on the use of any type of lightweight fill for slope stabilization by reducing the driving forces are available. Therefore, the proposed interim design guideline for EPS block geofoam can serve as a blueprint for the use of other types of lightweight fills in slope stability applications. The NCHRP Project 24-11(01) and the Project 24-11(02) Phase I research confirmed that EPS block geofoam is a unique lightweight fill material and can provide a safe and economical solution for slope stabilization and repair.

Seismic Stability Analysis of Slopes Stabilized with EPS-Block Geofoam

The use of lightweight fill, such as EPS-block geofoam, is a slope stabilization procedure that can be used to reduce the weight of the sliding mass and, thereby, reduce the driving forces of the sliding mass. This paper proposes the use of the horizontal slice method (HSM) for seismic stability analysis of slopes stabilized or repaired with EPS-block geofoam.

Bridge Foundations Supported by EPS Geofoam Embankments on Soft Soil

EPS geofoam can be used to support highway bridge structures without the aid of deep foundations. The development of this technology is important to accelerate construction on soft compressible soil. EPS geofoam allows for the rapid construction of bridge foundations on such soils without the time and cost involved in installing traditional foundations. Because EPS geofoam is an extremely light weight fill, it can be used to avoid settlement impacts at bridge approaches. In Norway, bridges have been directly supported by EPS geofoam. Norwegian Public Roads Administration has pioneered this application for a few bridges underlain by soft, clayey deposit where the bridge structure rests solely on EPS geofoam blocks. Investigating bridge foundations supported by EPS geofoam embankments is a joint effort starting summer 2013 between the University of Utah, University of Memphis and Norwegian Public Roads Administration. This paper includes some tasks and conceptual designs that address development of performance goals, design criteria, material testing, prototype analyses, numerical modeling and constructability of this innovative bridge support system.

Creep Behavior of Recycled-Content Expanded Polystyrene Geofoam Under Compressive Loading

This paper presents conventional creep test results for 0, 15 and 30% recycled-content expanded polystyrene (EPS)-block geofoam. The tests were performed on 50-mm (2-in.) cubical specimens with a nominal density of 21.6 kg/m3 under different stress levels for more than 9 months. It is concluded that the creep strain of recycled-content EPS geofoam increases with time and stress level in a manner similar to virgin EPS geofoam. As with virgin EPS geofoam, the elastic-limit stress appears to be a threshold stress level for creep strain development in recycled-content EPS geofoam.

High-Strain Dynamic Pile Testing for the I‐40/I‐240 Interchange in Memphis, Tennessee

The I-40/I-240 Interchange Improvement Project includes the construction of a four-level interchange that will improve the eastbound and westbound traffic on Interstates I-40 and I-240 in Memphis, Tennessee. The new interchange will include two flyover ramps that will extend up to 25 m (80 feet) above roadway level and will be supported on pre-stressed concrete and steel pipe piles. The project was designed using Load and Resistance Factor Design (LRFD) and uses multiple-stage dynamic testing for the design and construction of pile foundations. Several methods for predicting long-term pile resistance were evaluated and recommendations for using the driving information to evaluate pile resistance are presented.