Co-digestion of ruminal content and blood from slaughterhouse industries: influence of solid concentration and ammonium generation.

At the present time, organic solid wastes from industries and agricultural activities are considered to be promising substrates for biogas production via anaerobic digestion. Moreover solids stabilisation is required before reutilization or disposal. Slaughterhouses are among the most important industries in Uruguay and produce 150,000 tons of ruminal content (RC) and 30,000 tons of blood per year. In order to determine the influence of the solids and blood contents, the ammonia inhibition and the inoculum adaptation co-digestion batch tests were performed. A set of experiences with TS concentration of 2.5%, 5% and 7.5% and different ratios of RC/blood were carried out using an inoculum from an UASB reactor. In all experiences fast blood hydrolisation was observed. A higher methane production was detected in the experiences with higher TS content. However, the fraction of solids degradation was lower in these experiences. A plateau in the biogas production was found. The free ammonia level, which was above the reported inhibitory levels, could explain this behaviour. After the inhibition period the biogas production restarted probably due to the biomass acclimatisation to the ammonia. In order to determine the inoculum adaptation a new experiment was performed. The inoculum used was the sludge coming from the first set of experiences. Based upon batch tests a 3.5 m3 pilot reactor was designed and started up. Ammonia inhibition was avoided by the start-up strategy and in two weeks the biogas production was 3.5 m3/d. The VS stabilisation with a solid retention time of 20 days was of 43%. The pilot reactor working at steady state had a TS concentration of 3-4% with a ratio of RC/blood of 10:1 at the entrance.     

Optimal control of the effects from industrial transportation on the environment

The paper discusses optimal control of ecosystem state for observation of a generalized monotonically varying random parameter. A model is proposed for the controlled vector random process, whose components are assigned acceptable ranges and the observations are performed discretely. __________ Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 6, pp. 40–44, June, 2006.     

软交换与3G网络互通关键技术分析

就软交换网络和WCDMAR4网络互通的关键技术进行了分析和探讨，并借此提出了对互通节点的技术要求。     

Influence of the second phase on the room-temperature tensile and creep deformation mechanisms of α-β titanium alloys: Part I. Tensile deformation

The effects of α and β phase interactions on the room-temperature tensile and creep deformation behavior of α + β titanium alloys with Widmanst?tten microstructures were studied using Ti-6.0 wt pct Mn and Ti-8.1 wt pct V as the model two-phase alloy systems. This article, Part I, deals with tensile deformation. It was found that when the α phase is present as thin (<10-μm) plates in the α + β alloys, significant twinning occurs. No significant twinning was observed in single-phase alloys with the same chemistry and similar grain size. Additionally, the β phase of Ti-8.1 V deforms by stress-induced hexagonal martensite (α′), while only twinning occurs in the single-phase β alloy with the same chemistry. Twinning in the α phase in association with stress-induced martensite (SIM) in the β phase was observed for the first time in a two-phase titanium alloy. This behavior is explained in terms of a number of factors including elastic interaction stresses between the α and β phases, coherency between the α phase and hexagonal martensite, and β phase stability.     

Identification of the adverse effect of nitrate on the phosphate release rate and improvement of EBPR process models.

The adverse effect of nitrate on the phosphate release rate in the anaerobic phase was observed and was hardly explainable with conventional EBPR process models. Four possible mechanisms were proposed including substrate competition, reduced fermentation, parallel reaction and sequential reaction. Batch experiments were designed and conducted to identify the dominant mechanism. Results showed that the sequential reaction was the only possible mechanism where only denitrification occurred if any nitrate existed in the anaerobic phase. Then the phosphate release following after the nitrate was completely removed. Nitrate inhibition effect was added into the PHA storage rate to incorporate the sequential reaction in the conventional ASM3 plus EAWAG bio-P module (ASM3 + P). Nitrate inhibition coefficient, K(I,NO,PAO) was found to be as low as 0.05 mg/L. This correlated well with experimental observation where no also meant that the anaerobic compartment of a continuous flow reactor could be seriously affected by the residual nitrate contained in the sludge recycle flow. This phenomenon caused overestimation of the phosphate uptake rate and consequently underestimation of PO4(3-) -P concentration. This problem was resolved by incorporation of a nitrate inhibition term in the ASM3 + P for more accurate simulation of the EBPR process.     

Design of a retention tank: comparison of stormwater quality models with various levels of complexity.

Stormwater quality simulation models are useful tools for the design and management of sewer systems. Modelling results are highly sensitive to experimental data used for calibration. This sensitivity is examined for three modelling approaches of various complexities (site mean concentration approach, event mean concentration approach and build-up, washoff and transport modelling approach) applied to a typical case study (design of a dry detention tank), accounting for the variability of calibration data and their effect on simulation results. Calibrated models with different calibration data sets were used to simulate 3 years of rainfall with different retention tank specific volumes. Annual pollutant load interception efficiencies were determined. Simulations results revealed (i) that there is no advantage in using the EMC model compared to the SMC model and (ii) that the BWT model resulted in higher design ratios than those given by the SMC/hydraulic approach. For both EMC and BWT models, using an increasing number n of events for calibration leads to narrower confidence intervals for the design ratios. It is crucial for design ratios to account for successive storm events in chronological order and to account for the maximum allowable flow to be transferred to the downstream WWTP.     

Development of a simple microsystems membrane probe card

Presented here are details of the development of a novel membrane integrated circuit (IC) probe card structure based on microsystems technology. The device design allows probing of both solder bumps and pads. A self-limiting sensor was integrated to prolong device lifetime. Comparison with and discussion of the use of modelling is made. Possible enhancements to the probing structure are discussed to improve alignment and measurements. Also shown is data using our microsystems probe card to access a simple IC device. Our device has a contact resistance of less than 0.5 Ω for a force of 0.004 N. A method to implement our probing structure for commercial application and the potential developments which can be made to improve its ease of use are then discussed.     

Vacuum degassing of chromium-nickel-molybdenum steel at the Magnitogorsk Metallurgical Combine

The Magnitogorsk Metallurgical Combine has conducted a study of the effect of technological factors on the hydrogen content of chromium-nickel-molybdenum steel after vacuum degassing. It was established that the most important factor is the hydrogen content of the steel before the degassing operation. The study also determined the effects of the circulation coefficient, the duration of the degassing operation, and the vacuum used in the treatment. __________ Translated from Metallurg, No. 7, pp. 68–69, July, 2006.     

The Applied Mathematics and Computer Science Schism

Isolating applied mathematics from computer science harms the profession and those who depend on it.