Simultaneous heterotrophic and sulfur-oxidizing autotrophic denitrification process for drinking water treatment: control of sulfate production

A long-term performance of a packed-bed bioreactor containing sulfur and limestone was evaluated for the denitrification of drinking water. Autotrophic denitrification rate was limited by the slow dissolution rate of sulfur and limestone. Dissolution of limestone for alkalinity supplementation increased hardness due to release of Ca²⁺. Sulfate production is the main disadvantage of the sulfur autotrophic denitrification process. The effluent sulfate concentration was reduced to values below drinking water guidelines by stimulating the simultaneous heterotrophic and autotrophic denitrification with methanol supplementation. Complete removal of 75 mg/L NO₃-N with effluent sulfate concentration of around 225 mg/L was achieved when methanol was supplemented at methanol/NO₃-N ratio of 1.67 (mg/mg), which was much lower than the theoretical value of 2.47 for heterotrophic denitrification. Batch studies showed that sulfur-based autotrophic NO₂-N reduction rate was around three times lower than the reduction rate of NO₃-N, which led to NO₂-N accumulation at high loadings.     

Removal of ammonium from human urine through ion exchange with clinoptilolite and its recovery for further reuse.

Ammonium, from separately collected human urine, had been removed through transfer onto the ammonium selective natural zeolite, clinoptilolite, through ion exchange. In the subsequent treatment steps of washing with tap water, ammonium removed from urine was eluted from the surface of the clinoptilolite to be recovered for further reuse. Different quantities of clinoptilolite were used for a survey of the capacity of the zeolite for the process and to identify removal efficiencies based on initial ammonium loads. The highest surface concentration attained under experimental conditions employed was 15.44 mg ammonium per gram of clinoptilolite for an initial concentration of 110 mg ammonia per litre, and the highest removal was 98%, obtained for a loading of 1 mg ammonium per gram clinoptilolite. In the subsequent elution process, better removals were observed as pH was increased and the highest removal was attained at pH 13. The recovery was calculated as 9.73 mg ammonium per gram of clinoptilolite, corresponding to an efficiency of 63% only through washing with tap water. The results have given positive indications for the possibility of using ion exchange with clinoptilolite for the removal of ammonium from human urine and an incentive for improving methods of elution for its recovery for further reuse.     

Penetration Depth of Edge Magnetoplasmons

The magnetic-field variation of the penetration depth for edge magnetoplasmons in a two-dimensional sample of electrons on a helium surface is deduced from measurements of the linewidth and amplitude of the mode. A qualitative comparison between experimental values and theory is given.     

Failure mechanism of FBGA solder joints in memory module subjected to harmonic excitation

This paper investigates the failure mechanism of Fine-pitch Ball Grid Array (FBGA) solder joints of memory modules due to harmonic excitation by the experiments and the finite element method. A finite element model of the memory module was developed, and the natural frequencies and modes were calculated and verified by experimental modal testing. Modal damping ratios are also obtained and used in the forced vibration analysis. The experimental setup was developed to monitor resistance variation of FBGA solder joints due to the harmonic excitation under Joint Electron Devices Engineering Council (JEDEC) standard service conditions. Experiments showed that the failure of the solder joints of the memory module under vibration mainly occurs due to resonance. Forced vibration analysis was performed to determine the solder joints having high stress concentration under harmonic excitation. It showed that failure occurs due to the relative displacement between PCB and package and solder joints are the most vulnerable part of the memory module under vibration. It also showed that cracked solder joints in the experiments match those in the simulations with the highest stress concentration.     

Effects of MK-886, a leukotriene biosynthesis inhibitor, in a rabbit model of endotoxic shock

The aim of this study was to characterise the release of calcitonin gene-related peptide (CGRP) by capsaicin, low pH and prostacyclin in terms of Ca2+ channel dependence, interactions with K(ATP) channels and the role of action potential propagation, in the isolated, perfused guinea-pig heart. The Ca2+ channel blocker omega-conotoxin reduced CGRP release evoked by 10(-7) M capsaicin, as well as CGRP release evoked by pH 7. CGRP release caused by capsaicin at low (10(-7) M) but not high (10(-6) M) concentrations was also attenuated by tetrodotoxin, indicating partial dependence on action potential propagation. CGRP release caused by prostacyclin was not altered by any of the tested drugs. The K(ATP) channel activator cromakalim and the K(ATP) channel blocker glibenclamide had no effect on CGRP release. Previous findings that low pH and capsaicin stimulate capsaicin-sensitive afferents in the isolated heart at least partly through common mechanisms are thus supported. Attenuation of capsaicin-evoked release of CGRP by tetrodotoxin suggests recruitment of additional nerve terminals by a local axon reflex.     

Automated control and monitoring of thermal processing using high temperature, short time pasteurization

High temperature, short time pasteurization was used to evaluate a computer-based system for controlling the pasteurization process, acquiring data, and monitoring records. Software was used for the control of hot water temperature, flow rate through the centrifugal timing pump, and diversion of under-processed product. Three types of control strategies were conducted: single loop, cascade, and multivariable. The single loop control strategy showed the most rapid responses to temperature changes, but the temperature response curve was slowest to return to its set point. The cascade control strategy showed slower recoveries to temperature changes, but the temperature response curve was smoother. The multivariable control strategy responded slightly faster than the cascade control strategy, and the temperature response curve was slightly smoother than the cascade control strategy. The multivariable control strategy was able to control the flow diversion valve by the use of a lethality controller. The data acquisition system, used to monitor the data obtained from the high temperature, short-time pasteurization system, was within +/- 0.1 degree C of the temperature recorded by the safety thermal limit recorder. Reliability was determined by examining the changes in the position of the flow diversion valve to identify process deviations and by comparing the changes to the event marker on circular charts. The data acquisition system was an effective alternative for monitoring the completeness of data.     

Detection and Identification of Vehicles Based on Their Unintended Electromagnetic Emissions

When running, vehicles with internal combustion engines radiate electromagnetic emissions that are characteristic of the vehicle. Emissions depend on the electronics, harness wiring, body type, and many other features. Since emissions are unique to each vehicle, these may be used for identification purposes. This paper investigates a procedure for detecting and identifying vehicles based on their RF emissions. Parameters like the average magnitude or standard deviation of magnitude within a frequency band were extracted from measured emission data. These parameters were used as inputs to an artificial neural network (ANN) that was trained to identify the vehicle that produced the emissions. The approach was tested using the emissions captured from a Toyota Tundra, a GM Cadillac, a Ford Windstar, and ambient noise. The ANN was able to classify the source of signals with 99% accuracy when using emissions that captured an ignition spark event     

A Review on the Mechanical Modeling of Composite Manufacturing Processes

The increased usage of fiber reinforced polymer composites in load bearing applications requires a detailed understanding of the process induced residual stresses and their effect on the shape distortions. This is utmost necessary in order to have more reliable composite manufacturing since the residual stresses alter the internal stress level of the composite part during the service life and the residual shape distortions may lead to not meeting the desired geometrical tolerances. The occurrence of residual stresses during the manufacturing process inherently contains diverse interactions between the involved physical phenomena mainly related to material flow, heat transfer and polymerization or crystallization. Development of numerical process models is required for virtual design and optimization of the composite manufacturing process which avoids the expensive trial-and-error based approaches. The process models as well as applications focusing on the prediction of residual stresses and shape distortions taking place in composite manufacturing are discussed in this study. The applications on both thermoset and thermoplastic based composites are reviewed in detail.     

A case study on the methane explosion in the excavation chamber of an EPB-TBM and lessons learnt including some recent accidents

This study is related to a case concerning a methane explosion occurred inside the excavation chamber of an EPB-TBM in Silivri-Istanbul on the 20th of May in 2010. The authors of the paper were nominated as official inspectors of the court. A literature survey is first carried out in order to review similar accidents happened worldwide. Causes and effects of the explosion are analyzed later in detail. Precautions against methane emission are also summarized. It is concluded that a methane explosion inside the excavation chamber of an EPB-TBM is a very rare case and was not reported in the literature as the authors’ best knowledge. Oxygen necessary for methane explosion came from the foam used in the excavation chamber. Explosion occurred probably due to sparking caused by friction between screw conveyor and its casing. It is recommended that further research studies should focus on producing more secure foams being functional without oxygen, a methane detector should also placed inside the chamber with a power cut-off system.