Organic matter release in low temperature thermal treatment of biological sludge for reduction of excess sludge production.

Thermal treatment applied in association with a biological system allows for a significant reduction in excess sludge production (approximately 50%). In general, heat treatment is described as a sludge disintegration technique. This paper offers a thorough study on the impact of heat treatment, at temperatures below 100 degrees C, on the solubilisation of the sludge COD and its biodegradability. Discontinuous heating experiments were performed on activated and digested sludge. At all temperatures tested the released COD for digested sludge was systematically higher than that for activated sludge (15 and 40%, respectively, at 95 degrees C for 40 min of contact time). For the first 30 min, a 1st order kinetic, with respect to the residual COD, was systematically found. In the range of 40-95 degrees C, digested sludge had a lower activation energy than activated sludge (26 kcal/mol compared to 70-160 kcal/mol). COD solubilisation is thus more positively influenced by temperature in the case of activated sludge. This may be due to the significant difference in the ratio of protein/carbohydrate in digested and activated sludge (1-5 and 0.2-0.7, respectively). The increase in the COD/TKN ratio in the solubilised fraction after thermal treatment of activated sludge suggests a preferential solubilisation of proteins over carbohydrates. Respirometric tests performed on the solubilised COD showed that whatever the sludge origin, only 40-50% of released COD is biodegradable at a conventional hydraulic retention time (i.e., 24 h). Hence, heat treatment would act more through organic matter solubilisation rather than by a biodegradability increase.     

Results of a User Study on 2D Hurricane Visualization

We present the results from a user study looking at the ability of observers to mentally integrate wind direction and magnitude over a vector field. The data set chosen for the study is an MM5 (PSU/NCAR Mesoscale Model) simulation of Hurricane Lili over the Gulf of Mexico as it approaches the southeastern United States. Nine observers participated in the study. This study investigates the effect of layering on the observer's ability to determine the magnitude and direction of a vector field. We found a tendency for observers to underestimate the magnitude of the vectors and a counter‐clockwise bias when determining the average direction of a vector field. We completed an additional study with two observers to try to uncover the source of the counter‐clockwise bias. These results have direct implications to atmospheric scientists, but may also be able to be applied to other fields that use 2D vector fields.     

A Low-Power Reconfigurable Logic Array Based on Double-Gate Transistors

A fine-grained reconfigurable architecture based on double gate technology is proposed and analyzed. The logic function operating on the first gate of a double-gate (DG) transistor is reconfigured by altering the charge on its second gate. Each cell in the array can act as logic or interconnect, or both, contrasting with current field-programmable gate array structures in which logic and interconnect are built and configured separately. Simulation results are presented for a fully depleted SOI DG-MOSFET implementation and contrasted with two other proposals from the literature based on directed self-assembly.     

Manifold mapping: a two-level optimization technique

In this paper, we analyze in some detail the manifold-mapping optimization technique introduced recently [Echeverría and Hemker in space mapping and defect correction. Comput Methods Appl Math 5(2): 107—136, 2005]. Manifold mapping aims at accelerating optimal design procedures that otherwise require many evaluations of time-expensive cost functions. We give a proof of convergence for the manifold-mapping iteration. By means of two simple optimization problems we illustrate the convergence results derived. Finally, the performances of several variants of the method are compared for some design problems from electromagnetics.     

Integrating trust into the CyberCraft Initiative via the Trust Vectors model [Application Notes]

This research supports the hypothesis that the Trust Vector model can be modified to fit the CyberCraft Initiative, and that there are limits to the utility of historical data. This research proposed some modifications and expansions to the Trust Model Vector, and identified areas for future research.     

Effect of broaching on high-temperature fatigue behavior in notched specimens of INCONEL 718

Notches were machined in specimens of INCONEL 718 by a broaching process, where differing broaching runs led to differing extents of subsurface deformation and surface roughness. Fatigue tests were carried out at 600 °C with a trapezoidal loading waveform at 0.25 Hz. The broaching process that led to the more severe subsurface deformation (but lower surface roughness) showed the worst fatigue performance. Analysis of total strain amplitude in the notch root with the aid of an elastoplastic finite-element (FE) model showed that the work hardening related to the subsurface deformation caused by the different broaching can account for the difference in fatigue lives. Differences in initiation and growth behavior were seen for the two broached finishes as well as for broached and subsequently polished samples. These differences are discussed in terms of a change in crack growth initiation and growth mechanisms due to the presence of the work-hardened layer.     

Performance of simple response method for the establishment and adjustment of calibration intervals

Managing calibration intervals in order to fulfill requirements of quality-oriented organizations is discussed in this paper. In particular, the simple response method is considered. According to this technique, the interval between successive calibrations is adjusted adaptively on the basis of the outcome of the last calibration process. An original analysis is presented about the properties of such calibration interval handling methods. Finally, directions are given on how to tune its parameters optimally, in order to meet desired levels of long-term measurement reliability.