The growth of ferrite in Fe-C-X alloys: The role of thermodynamics, diffusion, and interfacial conditions

The growth of allotriomorphic ferrite from austenite in Fe-C-X alloys is studied. Two systems have been selected: the Fe-C-Ni system, in which the substitutional alloying element is expected to have a weak interaction with both the C and the moving interface, and the Fe-C-Mo system, in which these interactions are expected to be non-negligible. The ferrite growth kinetics was measured using two types of experiments: classical isothermal heat treatments and decarburization experiments. All of the experimental observations can be quantitatively rationalized using a model that describes an evolution in interfacial conditions from paraequilibrium (PE) to local equilibrium with negligible partitioning (LENP) during growth. This article is based on a presentation made in the “Hillert Symposium on Thermodynamics & Kinetics of Migrating Interfaces in Steels and Other Complex Alloys,” December 2–3, 2004, organized by the The Royal Institute of Technology in Stockholm, Sweden.     

Effect of steel fibres at two different stages: The material and the structure

The addition of steel fibres to plain concrete is intended both to improve the material's ductility and that of the structure in which it is used. These two effects of steel fibres are clearly distinguishable through an analysis of cracking both at a local and a global level. This analysis is essential if the use of steel fibres is to be optimized.     

Intracavity Raman lasers

Experimental and theoretical studies of intracavity Raman lasers are presented. Advantages of intracavity Raman lasers, particularly for low-emission cross section and broadly tunable vibronic gain media, are described. Experimental studies of a hydrogen gas Raman laser pumped inside the cavity of an alexandrite laser are presented. A theoretical model of the dynamics of a unidirectional intracavity Raman ring laser is developed and solved analytically. This model is adapted for simulation experiments     

Multichip Differential Phase-Shift-Keyed Transmission Over (Non)Linear Optical Channels

The recently introduced multichip differential phase-shift keying (MC-DPSK) optical transmission format, entailing the modulation of relative phases over a moving transmission window of successive chip intervals, is analytically and numerically analyzed. The maximum-likelihood optimal MC-DPSK receiver is derived and synthesized using integrated-optic Mach-Zehnder delay interferometers, whose electrical outputs are interpreted as generalized Stokes' parameters. The MC-DPSK performance over a nonlinear fiber channel, limited by the combination of amplified spontaneous emission noise and self-phase modulation, is further derived and simulated, demonstrating that the lowest complexity three-chip binary-phase MC-DPSK receiver provides an ~1-dB Q-factor advantage over conventional DPSK.     

Strategy for olive mill wastewater treatment and reuse with a sewage plant in an arid region.

This study was conducted to evaluate the treatability of OMW (olive mill wastewater) with sewage and sewage sludge, which could supplement nutrients and microbes required for OMW treatment and reduce its possible toxicity. The amount of OMW added to an aeration tank was based on the loading difference between the designed and actual COD loads, while the amount added to anaerobic digestion for energy recovery was determined by CH4 production. The COD removal efficiencies were 70-85% for both systems. Compost of OMW with dried sewage sludge also showed a similar temperature profile without OMW addition. This strongly suggested that OMW can be treated at a sewage plant without pretreatment and the treated effluent can be reused in irrigation for an arid region.     

Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions.

Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.     

A typical meteorological day (TMD) approach for predicting the long-term performance of solar energy systems

A method for predicting the long-term performance of solar energy systems, based on the analysis of system performance for one particular day—the typical meteorological day (TMD)—is presented. The TMD is constructed from the cumulative time distribution of insolation values on the collector aperture. The TMD method requires little calculational effort and a small data base relative to standard yearly computer simulations. Good agreement is found between the predictions of the new method and the corresponding results of the -f-chart method. The TMD method is of particular value for cases that may often be treated inaccurately by simple calculational methods: (1) high threshold problems; (2) systems with short response times (e.g., due to small storage); and (3) systems in which collectors other than flat plates are used (the method is applicable to all solar collector types).     

Eigen filter to detect volitional EMG signals in autogenic EMG-controlled FES

Presented is an eigen filter to remove autogenic electrical stimulation artefacts and M-waves while preserving the volitional electromyographic signal. The optimality of the eigen filter is shown, along with simulated and measured data to indicate its superior performance over conventional prediction error filters.