Soil aquifer treatment (SAT) systems are used for reclamation of sewage effluent by groundwater recharge. Increasing demand on water supplies has stimulated the production or planning of many SAT ...systems that will use reclaimed wastewater for groundwater recharge. These systems are comprised of a series of filtration basins. The design and operation of soil aquifer treatment systems presently relies primarily upon dgment and experience. This research effort is developing a methodology for determining the optimal peration of SAT systems that is based upon mathematically describing the problem as a discrete-time ptimal control problem. The resulting mathematical problem is a large-scale nonlinear programming problem. Solution of the problem is being accomplished by interfacing a nonlinear programming optimizer, which is solved by a differential dynamic programming algorithm, with a simulator that describes the filtration process, unsaturated flow, effects of surface clogging and biological clogging, biological removal of nitrogen and organics. Major efforts are devoted to numerical performance of the optimization model elution, and development of the simulator. Initial results of interfacing the optimizer with the simulator without water quality concern show high convergence rate. The operation pattern determined by this method reasonable. This new methodology will be a tool for engineers to evaluate choices regarding the potential of the design and operation of SAT systems.
In the Dan Region Reclamation Center (DRRC) in Israel, secondary effluents, after a mechanical - biological treatment and polishing ponds, undergo a Soil-Aquifer Treatment (SAT) , in the course of ...which these are recharged into an isolated aquifer, and the repumped water is used for various agricultural purposes. In the present study a simple model has been developed in order to predict retardation factors and breakthrough times of various micropollutants in the SAT system. The model is based on the linear free energy relationship between adsorbtivity of organic compounds and their hydrophobicity as expressed by their octanol - water partition coefficients. A very good correlation was found between the predicted values calculated by the model, and experimental laboratory results of adsorption isotherms and breakthrough curves.
The objective of this study was to investigate the application of constructed wetlands as a mean to manage olive mill wastewater (OMW). Two free water surface (FWS) constructed wetlands, one without ...(CW1) and one with effluent recirculation (CW2), were operated for a two-year period with diluted OMW (1:10) and evaluated in terms of the removal of COD, TSS, TKN, NH4+-N, NO3−-N, TP and total phenols. The organic loading rate of CWs was adjusted to 925 kg BOD/ha·d. In CW1 the removal efficiency averaged 80%, 83%, 78%, 80%, and 74% for COD, TSS, TKN, TP, and total phenols, respectively, during the operation period. Effluent recirculation further improved the treatment efficiency which approached 90%, 98%, 87%, 85%, and 87% for COD, TSS, TKN, TP, and total phenols, respectively. Constructed wetlands also showed high removal efficiency for NH4+-N. Nitrate concentration maintained low in both CWs basins, probably due to the prevalence of high denitrification rates that efficiently removed the NO3--N produced by NH4+-N oxidation. Despite the increased removal percentages, pollutant concentration in effluent exceeded the allowable limits for discharge in water bodies, suggesting that additional practices, including enhanced pre-application treatment and/or higher dilution rates, are required to make this practice effective for OMW management.
The Cosmic Background Imager 2 Taylor, Angela C; Jones, Michael E; Allison, James R ...
arXiv.org,
08/2011
Paper, Journal Article
Odprti dostop
We describe an upgrade to the Cosmic Background Imager instrument to increase its surface brightness sensitivity at small angular scales. The upgrade consisted of replacing the thirteen 0.9-m ...antennas with 1.4-m antennas incorporating a novel combination of design features, which provided excellent sidelobe and spillover performance for low manufacturing cost. Off-the-shelf spun primaries were used, and the secondary mirrors were oversized and shaped relative to a standard Cassegrain in order to provide an optimum compromise between aperture efficiency and low spillover lobes. Low-order distortions in the primary mirrors were compensated for by custom machining of the secondary mirrors. The secondaries were supported on a transparent dielectric foam cone to minimize scattering. The antennas were tested in the complete instrument, and the beam shape and spillover noise contributions were as expected. We demonstrate the performance of the telescope and the inter-calibration with the previous system using observations of the Sunyaev-Zel'dovich effect in the cluster Abell 1689. The enhanced instrument has been used to study the cosmic microwave background, the Sunyaev-Zel'dovich effect and diffuse Galactic emission.
Coherent phenomena in two band photonic crystals Angelakis, D.G.; Paspalakis, E.; Knight, P.L.
Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504),
2000
Conference Proceeding
Summary form only given. The majority of studies of quantum optical processes occurring in atoms interacting with modified reservoirs, such as microcavities and photonic band gap materials, have ...concentrated on spontaneous emission dynamics. In this paper we report our recent theoretical results on absorption and dispersion dynamics of a A-type system where one transition spontaneously decays in a two band photonic reservoir. The coupling to this modified reservoir leads to a non-Markovian spontaneous decay of the atomic state, which in return influences the dispersion and absorption properties of a probe laser pulse coupling to the other atomic transition.
The Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope provides an unprecedented opportunity to study gamma-ray blazars. To capitalize on this opportunity, beginning in late 2007, ...about a year before the start of LAT science operations, we began a large-scale, fast-cadence 15 GHz radio monitoring program with the 40-m telescope at the Owens Valley Radio Observatory (OVRO). This program began with the 1158 northern (declination>-20 deg) sources from the Candidate Gamma-ray Blazar Survey (CGRaBS) and now encompasses over 1500 sources, each observed twice per week with a ~4 mJy (minimum) and 3% (typical) uncertainty. Here, we describe this monitoring program and our methods, and present radio light curves from the first two years (2008 and 2009). As a first application, we combine these data with a novel measure of light curve variability amplitude, the intrinsic modulation index, through a likelihood analysis to examine the variability properties of subpopulations of our sample. We demonstrate that, with high significance (7-sigma), gamma-ray-loud blazars detected by the LAT during its first 11 months of operation vary with about a factor of two greater amplitude than do the gamma-ray-quiet blazars in our sample. We also find a significant (3-sigma) difference between variability amplitude in BL Lacertae objects and flat-spectrum radio quasars (FSRQs), with the former exhibiting larger variability amplitudes. Finally, low-redshift (z<1) FSRQs are found to vary more strongly than high-redshift FSRQs, with 3-sigma significance. These findings represent an important step toward understanding why some blazars emit gamma-rays while others, with apparently similar properties, remain silent.
Phys. Rev. A 64, 013801 (2001) We study the spontaneous emission, the absorption and dispersion properties
of a ${\bf \Lambda}$-type atom where one transition interacts near resonantly
with a ...double-band photonic crystal. Assuming an isotropic dispersion relation
near the band edges, we show that two distinct coherent phenomena can occur.
First, the spontaneous emission spectrum of the adjacent free space transition
obtains `dark lines' (zeroes in the spectrum). Second, the atom can become
transparent to a probe laser field coupling to the adjacent free space
transition.
Phys. Rev. A 61, 055802 (2000) We investigate the transient response of a $\Lambda$-type system with one
transition decaying to a modified radiation reservoir with an inverse
square-root singular ...density of modes at threshold, under conditions of
transparency. We calculate the time evolution of the linear susceptibility for
the probe laser field and show that, depending on the strength of the coupling
to the modified vacuum and the background decay, the probe transmission can
exhibit behaviour ranging from underdamped to overdamped oscillations.
Transient gain without population inversion is also possible depending on the
system's parameters.
Opt.Commun. 172 (1999) 229 We study two distinct multi-level atomic models in which one transition is
coupled to a Markovian reservoir, while another linked transition is coupled to
a non-Markovian ...reservoir. We show that by choosing appropriately the density
of modes of the non-Markovian reservoir the spontaneous emission to the
Markovian reservoir is greatly altered. The existence of `dark lines' in the
spontaneous emission spectrum in the Markovian reservoir due to the coupling to
specific density of modes of the non-Markovian reservoir is also predicted.
