Biological Removal of Gaseous VOCs from Automotive Painting Operations

Among the pollutants that automotive plants produce, volatile organic compound (VOC) emissions due to paint solvents from painting operations are the largest in quantity. The current control process, based on vapor-phase adsorption followed by thermal oxidation, is costly to install and operate. At Ford, a cost-effective method of removing VOCs has been investigated that involves converting an existing spraybooth scrubber system to a biological reactor. This paper reports the results of a pilot-scale investigation in which two activated-sludge bioreactors, one with and the other without powdered activated carbon (PAC), were operated in parallel for 16 months. The primary findings include (1) The biological VOC removal process was technically feasible, and a scrubber system at a typical assembly plant is sufficiently large to handle the solvent loading used under normal vehicle-production conditions; (2) as compared to the adsorption∕thermal oxidation process, the biological process was found to be comparable in VOC removal efficiency, an order of magnitude more cost-effective in capital cost, and a factor of two more cost-effective in operating and maintenance cost; and (3) the bioreactors effectively captured and degraded hydrophilic paint solvents (methyl ethyl ketone, n-butanol, and butyl cellosolve) that were fed via the vapor phase. Toluene, a hydrophobic solvent, was also well-captured and degraded (74 to 91% without PAC and 86 to 93% with PAC).     

Efficient finite-difference scheme for solving some heat transfer problems with convection in multilayer media

An efficient finite-difference method for solving the heat transfer equation with piecewise discontinuous coefficients in a multilayer domain is developed. The method may be considered as a generalization of the finite-volumes method for the layered systems. We apply this method with the aim to reduce the 3D or 2D problem to the corresponding series of 2D or 1D problems. In the case of constant piecewise coefficients, we obtain the exact discrete approximation of the steady-state 1D boundary-value problem.     

Are Coaxial Super Power Gyrotrons Feasible?

Limits on the power generated by coaxial gyrotrons are investigated. It is shown that among all the operating modes suggested recently for coaxial super power gyrotrons only modes with azimuthal index m lower than about 44 pass the spatial stochasticity test. Modes with higher azimuthal indices cannot be used as operating modes because gyrotron oscillations become chaotic in the azimuthal direction and efficiency is very low. It is argued that there exists a natural upper limit on power generated by gyrotrons which is about 4 MW.     

Measuring free metal ion concentrations in situ in natural waters using the Donnan Membrane Technique

Metal toxicity is not related to the total but rather to the free or labile metal ion concentration. One of the techniques that can be used to measure several free metal ion concentrations simultaneously is the Donnan Membrane Technique (DMT) in combination with the inductively coupled plasma-mass spectrometer (ICP-MS). However, free metal ion concentrations in natural waters are commonly below the detection limit of ICP-MS. We decreased the detection limit by making use of a ligand, and we developed a field DMT cell that can be applied in situ in natural waters. A kinetic approach can be used to calculate free metal ion concentrations when the equilibrium time becomes too large. The field DMT measured in situ in natural waters a free metal ion concentration ranging from 0.015% (Cu) to 13% (Zn) of a total metal concentration ranging from 0.06 nM (Cd) to 237 nM (Zn). The free metal ion concentrations were difficult to predict using an equilibrium speciation model, probably due to the uncertainty in the nature of the dissolved organic matter or the presence of other reactive colloids. It is shown that DMT can follow changes in the free metal ion concentration on times scales less than a day under certain conditions.     

Palmoplantar filiform parakeratotic hyperkeratosis and digestive adenocarcinoma

BACKGROUND: The rapid integration of new technology into ophthalmologic practice, e.g. LASIK (laser in situ keratomileusis), is associated with new complications. The limitations of the new technology cannot be precisely determined. During lamellar cuts with microkeratomes intraocular pressure (IOP) elevations occur. The IOP elevation during the lamellar cut cannot be determined by conventional tonometry. MATERIALS AND METHOD: We examined the IOP rise during the complete microkeratome treatment. Fresh enucleated porcine eyes were cannulated and direct IOP measurement with a Statham manometer was carried out. Thus we evaluated the IOP during the complete treatment for two differently constructed microkeratome systems. RESULTS: IOP elevations (mean values) between 77 mm Hg for the Corneal Shaper and 229 mm Hg for the Keratek during the vacuum phase and 140 mm Hg for the Corneal Shaper and 360 mm Hg for the Keratek during the lamellar cut were monitored. A sudden IOP decrease to-5 mm Hg was registered for the post-vacuum phase. CONCLUSIONS: In our opinion unphysiologic high IOP values could be dangerous for risk eyes.     

Pattern diversity for single RF user terminals in multiuser environments

Although the utilization of multiple antennas enhances significantly the performance of multiuser systems, it is prohibitive for mobile devices due to size and power restrictions. In order to alleviate this problem we propose an alternative mobile architecture, built on compact antenna structures with fast beamforming capabilities. It is shown that the proposed architecture combined with a simple training procedure, enhances the average throughput of a multiuser system. The performance is compared with that of user devices with one or three antenna elements employing maximal ratio combining.     

Link Performance of an ESPAR-Antenna Array in Rich Scattering and Clustered Channels

This paper aims at evaluating the link performance of an electronically steerable passive array radiator (ESPAR) in both rich scattering and clustered channels. Previous work has shown that the performance of an ESPAR-antenna can be comparable to a 2 × 2 multiple-input-multiple-output (MIMO) system in a rich scattering environment. The design of the antenna patterns used for transmission was based on intuition, and therefore cannot be guaranteed to be optimal. In this paper, we design the antenna patterns by minimizing the average inner-product between signals that are transmitted with different antenna patterns. We also evaluate the performance of the ESPAR-antenna at higher spectral-efficiencies than previous literature has done. The performance in terms of spectral-efficiency is evaluated for both rich scattering environments and clustered channels, whereas the performance in terms of symbol error rate is evaluated for rich scattering channels only.

Photochemical Destruction of Cyanide in Landfill Leachate

The Allen Park Clay Mine Landfill, owned by Ford, produces a leachate that occasionally contains cyanide at levels marginally below the discharge limit. The form of the cyanide in the leachate was found to be iron-cyanide complexes that resist oxidation by a conventional treatment method, alkaline oxidation. Furthermore, the leachate also was found to contain a relatively large amount of organics (>1,000 mg∕L of chemical oxygen demand), which would exert additional demand for oxidizing agents (e.g., chlorine). A study was performed to determine what treatment technology could be employed in the event treatment becomes necessary because of potential changes in the leachate characteristics and∕or discharge limits. In this study, among several chemical oxidation methods, ultraviolet (UV) irradiation with or without ozone was investigated as a treatment option. The following are the primary findings: (1) UV irradiation alone was effective for removing the iron-cyanide complex in both the leachate and the clean water; (2) the demand for UV or ozone by chemical oxygen demand was relatively low for this leachate; (3) ozone alone was not effective for removing the iron-cyanide complex; and (4) UV irradiation alone and UV irradiation with ozone resulted in the same removal for total cyanide in clean-water experiments, but the UV irradiation alone left some free cyanide whereas the UV irradiation with ozone did not.     

MIMO transmission and reception techniques using three-element ESPAR antennas

A novel scheme for spatially multiplexing two BPSK signals using a 3-element ESPAR (electronically steerable parasitic array radiator) antenna was reported in. In this paper we first optimize the set of loads controlling the parasitic elements within the transmission mode by maximizing the outage capacity. We also propose different reception techniques for spatially demultiplexing real and complex signals (using the same set of loads). The proposed transmission and reception schemes are evaluated in an indoor peer-to-peer mobile ad-hoc channel via simulations, where each ad-hoc node is equipped with a 3-element ESPAR terminal.