Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds

This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser detection. Standoff distances for pulsed measurements were 35 m for dimethyl methylphosphonate (DMMP) detection and 60, 90 and 140 m for cyclohexane detection. The prototype systems consisted of a Raman spectrometer equipped with a CCD detector (for CW measurements) and an I-CCD camera with time-gated electronics (for pulsed laser measurements), a reflecting telescope, a fiber optic assembly, a single-line CW laser source (514.5, 488.0, 351.1 and 363.8 nm) and a frequency-doubled single frequency Nd:YAG 532 nm laser (5 ns pulses at 10 Hz). The telescope was coupled to the spectrograph using an optical fiber, and filters were used to reject laser radiation and Rayleigh scattering. Two quartz convex lenses were used to collimate the light from the telescope from which the telescope-focusing eyepiece was removed, and direct it to the fiber optic assembly. To test the standoff sensing system, the Raman Telescope was used in the detection of liquid TIC: benzene, chlorobenzene, toluene, carbon tetrachloride, cyclohexane and carbon disulfide. Other compounds studied were CWAS: dimethylmethyl phosphonate, 2-chloroethyl ethyl sulfide and 2-(butylamino)-ethanethiol. Relative Raman scattering cross sections of liquid CWAS were measured using single-line sources at 532.0, 488.0, 363.8 and 351.1 nm. Samples were placed in glass and quartz vials at the standoff distances from the telescope for the Remote Raman measurements. The mass of DMMP present in water solutions was also quantified as part of the system performance tests.     

Sensor fault detection and isolation via high-gain observers: application to a double-pipe heat exchanger

This paper deals with fault detection and isolation (FDI) in sensors applied to a concentric-pipe counter-flow heat exchanger. The proposed FDI is based on the analytical redundancy implementing nonlinear high-gain observers which are used to generate residuals when a sensor fault is presented (as software sensors). By evaluating the generated residual, it is possible to switch between the sensor and the observer when a failure is detected. Experiments in a heat exchanger pilot validate the effectiveness of the approach. The FDI technique is easy to implement allowing the industries to have an excellent alternative tool to keep their heat transfer process under supervision. The main contribution of this work is based on a dynamic model with heat transfer coefficients which depend on temperature and flow used to estimate the output temperatures of a heat exchanger. This model provides a satisfactory approximation of the states of the heat exchanger in order to allow its implementation in a FDI system used to perform supervision tasks.     

Note: fast, small, and low vibration mechanical laser shutters

We present three novel mechanical laser shutter designs based, respectively, on a stepper motor, a relay, and a piezoelectric actuator. Each shutter type is ideally suited to a specific shuttering application. The stepper motor is well suited for applications requiring low vibrations, the relay is compact and capable of rapid bursts, and the piezoelectric is 2 orders of magnitude faster than other available mechanical shutters.     

Maximum overall efficiency for a solar‐driven gas turbine power plant

A general model for an irreversible solar‐driven Brayton multi‐step heat engine is presented. The model incorporates an arbitrary number of turbines (N_t) and compressors (N_c) and the corresponding reheating and intercooling processes; thus, the solar‐driven Ericsson cycle is a particular case where N_t, N_c → ∞. For the solar collector, we assume linear heat losses, and for the Brayton multi‐step cycle, we consider irreversibilities arising from the non‐ideal behavior of turbines and compressors, pressure drops in the heat input and heat release, heat leakage through the plant to the surroundings, and non‐ideal couplings of the working fluid with the external heat reservoirs. We obtain the collector temperatures at which maximum overall efficiency η_max is reached as a function of the thermal plant pressure ratio, and a detailed comparison for several plant configurations is given. This maximum efficiency is obtained in two cases: when only internal irreversibilities are considered and when both internal and external irreversibilities (which corresponds to the fully irreversible realistic situation) are simultaneously taken into account. Differences between both situations are stressed in detail. In the fully irreversible realistic case, it is possible to perform an additional optimization with respect to the pressure ratio, . In particular, this double optimization leads to a valuable increase in efficiency (between 34% and 65%) for a plant with two turbines and two compressors compared to the simple solar‐driven one‐turbine one‐compressor Brayton engine. Copyright © 2012 John Wiley & Sons, Ltd.     

‘Extra oomph:’ addressing housing disparities through Medical Legal Partnership interventions

Low-income households face common and chronic housing problems that have known health risks and legal remedies. The Medical Legal Partnership (MLP) program presents a unique opportunity to address housing problems and improve patient health through legal assistance offered in clinical settings. Drawn from in-depth interviews with 72 patients, this study investigated the outcomes of MLP interventions and compares results to similarly disadvantaged participants with no access to MLP services. Results indicate that participants in the MLP group were more likely to achieve adequate, affordable, and stable housing than those in the comparison group. Study findings suggest that providing access to legal services in the healthcare setting can effectively address widespread health disparities rooted in problematic housing. Implications for policy and scalability are discussed with the conclusion that MLPs can shift professionals’ consciousness as they work to improve housing and health trajectories for indigent groups using legal approaches.     

Improvements in Mero River Basin Water Supply Regulation Through Integration of a Mining Pit Lake as a Water Supply Source

Seasonal increases in demand puts a strain on water supplies in the city of La Coruña (northwest Spain) and its surroundings during times of drought. Exploitation of Meirama Lake, a pit lake forming in a former lignite mine, could supplement the Abegondo-Cecebre reservoir, the city’s main water supply. We analysed the hydrochemistry and the Mero River basin regulations to determine whether the water quantity and quality could meet the needs during periods of increased demand and drought, and still satisfy ecological conditions required by law. Our results indicated that joint use of the two reservoirs is feasible. The local administration is implementing the recommendations by building a tunnel to tap into the pit lake.     

Productivity growth of wastewater treatment plants – accounting for environmental impacts: a Malmquist-Luenberger index approach

As the number of wastewater treatment plants (WWTPs) has increased, the economic considerations associated with their management have become more relevant. Measuring the productivity of WWTPs allows the best practice to be identified and resource use to be optimized. Previous studies assessing the productivity change of WWTPs have ignored undesirable outputs; thus, wastewater treatment was considered to be free of environmental impacts. To overcome this limitation and for the first time, we assessed the productivity growth of a sample of Spanish WWTPs, while also accounting for the emission of greenhouse gases and sludge production. The Malmquist-Luenberger productivity index (MLPI) and its components, the efficiency and technological changes, were estimated. To explore the role of environmental impacts in the measurement of the productivity growth of WWTPs, the MLPI was contrasted with the conventional measurement of productivity change: namely, the Malmquist productivity index (MPI). The omission of undesirable outputs led to an underestimation of the productivity growth, with statistically significant differences between the MLPI and MPI results. The comparison of the MPI and MLPI illustrated that WWTP operators and water agencies have internalized some good environmental practices into their production process costs.     

Timing synchronization method for pilot‐based coherent detection

Cognitive radio systems play an important role in the current digital communication systems. With regard to the methods developed, the importance of a coherent detector with matched filters arises, taking into account the optimal properties verified in detection and sensing time. However, the need of perfect timing limits the applicability of this type of system, because of the complexity in hardware implementation. Based upon slope estimation techniques, the present article addresses new methods for tackling this problem. A low complexity system is obtained, and applications can be considered for finding white space in digital television. The results show a good performance with regard to the probability of detection and robustness regarding frequency offset. Copyright © 2015 John Wiley & Sons, Ltd.     

Economic and environmental optimization of the biobutanol purification process

Current technologies for the production of biobutanol by fermentation have improved the production processes. These new technology improvements are economically viable with respect to the petrochemical pathway. For this, the aim of this paper is to compare four different process designs for the purification of biobutanol by solving a multi-objective optimization process involving two objective functions: the total annual cost and return of investment as economic functions and the associated eco-indicator 99 as an environmental function. The process associated to the routes A, B, and C consists of a steam stripping distillation and distillation columns, while the process D includes distillation columns with a liquid–liquid extraction column. Process modeling was performed in the Aspen Plus software, and the multi-objective optimization was conducted using differential evolution with tabu list as a stochastic optimization method. Results indicate that the process route D is the most profitable design and the process route C has the lowest environmental impact measured through the eco-indicator 99 method. Additionally, the use of a solar collector against steam has been compared in order to produce the required heat duty needed in every single distillation column to have a broader view about the environmental and economic impact of these devices.