Both real events and models have proven that drinking water systems are vulnerable to deliberate and/or accidental
contamination. Additionally, homeland security initiatives and modeling efforts have determined that it is relatively easy
to orchestrate the contamination of potable water supplies. Such contamination can be accomplished with classic and
non-traditional chemical agents, toxic industrial chemicals (TICs), and/or toxic industrial materials (TIMs). Subsequent
research and testing has developed a proven network for detection and response to these threats. The method uses offthe-
shelf, broad-spectrum analytical instruments coupled with advanced interpretive algorithms. The system detects and
characterizes any backflow events involving toxic contaminants by employing unique chemical signature (fingerprint)
response data. This instrumentation has been certified by the Office of Homeland Security for detecting deliberate and/or
accidental contamination of critical water infrastructure. The system involves integration of several mature technologies
(sensors, SCADA, dynamic models, and the HACH HST Guardian Blue instrumentation) into a complete, real-time,
management system that also can be used to address other water distribution concerns, such as corrosion. This paper
summarizes the reasons and results for installing such a distribution-based detection and protection system.
Development of microfluidics has focused on carrying out chemical synthesis and analysis
in ever-smaller volumes of solution. In most cases, flow systems are made of either quartz,
glass, or an easily moldable polymer such as polydimethylsiloxane (Whitesides 2006). As the
system shrinks, the ratio of surface area to volume increases. For studies of either free radical
chemistry or protein chemistry, this is undesirable. Proteins stick to surfaces, biofilms grow on
surfaces, and radicals annihilate on walls (Lewis et al. 2006). Thus, under those circumstances
where small amounts of reactants must be employed, typical microfluidic systems are incompatible
with the chemistry one wishes to study. We have developed an alternative approach. We
use ultrasonically levitated microliter drops as well mixed microreactors. Depending on whether
capillaries (to form the drop) and electrochemical sensors are in contact with the drop or whether
there are no contacting solids, the ratio of solid surface area to volume is low or zero. The only
interface seen by reactants is a liquid/air interface (or, more generally, liquid/gas, as any gas may
be used to support the drop). While drop levitation has been reported since at least the 1940's,
we are the second group to carry out enzyme reactions in levitated drops, (Weis; Nardozzi 2005)
and have fabricated the lowest power levitator in the literature (Field; Scheeline 2007). The low
consumption aspects of ordinary microfluidics combine with a contact-free determination cell
(the levitated drop) that ensures against cross-contamination, minimizes the likelihood of biofilm
formation, and is robust to changes in temperature and humidity (Lide 1992). We report kinetics
measurements in levitated drops and explain how outgrowths of these accomplishments will lead
to portable chemistry/biology laboratories well suited to detection of a wide range of chemical
and biological agents in the asymmetric battlefield environment.
BlazeTech has recently developed a software called H2OFate to predict the fate and transport of chemical
and biological contaminants in water distribution systems. This software includes models for the
reactions of these contaminants with residual disinfectant in bulk water and at the pipe wall, and their
adhesion/reactions with the pipe walls. This software can be interfaced with sensors through SCADA
systems to monitor water distribution networks for contamination events and activate countermeasures, as
needed. This paper presents results from parametric calculations carried out using H2OFate for a
simulated contaminant release into a sample water distribution network.
Soil properties make a significant impact in the observed responses of various sensors for mine detection. Soil moisture affects the performance of electromagnetic sensors through its effects on soil thermal and dielectric properties. We have initiated laboratory, field and numerical studies to advance our fundamental understanding of the properties and governing processes of moisture distribution and flow around buried landmines. The laboratory component features magnetic resonance imaging (MRI) to map water distribution around a mine-like obstacle placed in a test soil sample. The field component investigates the moisture migration around landmines under realistic weather and soil conditions. We use anti-tank mines instrumented with moisture and temperature sensors to monitor the weather-driven processes. The numerical component investigates existing physics models underlying current simulations of moisture transport in soils. We use existing flow simulators to evaluate the completeness of process descriptions and to estimate the relative importance of individual processes on micro-scale moisture movement. These existing simulators include both continuum codes designed to work at scales much larger than the grain size and pore-scale models that discretize individual pores. We present the preliminary results of our investigations and discuss the potential impact of our findings on infrared and radar detection of buried landmines.
KEYWORDS: Signal to noise ratio, Land mines, Explosives, Signal detection, Data acquisition, Magnetism, Receivers, Nitrogen, Explosives detection, Temperature metrology
Nuclear quadrupole resonance (NQR) is well suited for detecting land mines with non-metallic cases. It provides both spatial localization and chemical identification of explosives. A search coil produces a train of radio frequency (RF) magnetic pulses that perturb the orientation of nitrogen nuclei contained within the explosive material. Following each RF pulse, the nuclei rotate back to orientations of lower energy. As the nitrogen nuclei possess a magnetic moment, their motion following an RF pulse induces a detectable voltage in the search coil. The NQR signal strength depends on the amplitude, frequency, duration and repetition rate of the applied RF pulses. The optimal selection of RF parameters requires knowledge that is not available in practice, such as the location of the explosive with respect to the search coil. Existing NQR detection systems sacrifice signal intensity by using field pulse parameters. We demonstrate that feedback control provides a means for automatically adjusting multiple pulse parameters so that the maximum NQR signal strength is obtained. The advantages afforded to landmine detection using feedback NQR are summarized.
Fluorescence spectroscopy of the human thymus gland and surrounding mediastinal fat were measured to evaluate this approach in distinguishing between thymus and fat tissues during therapeutic surgery for myasthenia gravis disease.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.