Effect of Amblyomma cajennense Ticks on the Immune Response of BALB/c Mice and Horses

This work evaluated the effect of the Amblyomma cajennense tick on the immune response of BALB/c mice and on horse lymph node cell proliferation. We observed that mice do not develop resistance to nymphs of this tick species and that lymphocyte proliferation of this host is inhibited by tick saliva, nymphal extract, or infestations. Horse lymph node cell proliferation is inhibited by tick saliva as well. Mice lymphocytes under the effect of tick saliva, nymphal extract, or infestations display a predominantly. p Th-2 cytokine production pattern. Observed results partially explain this tick`s disease vectoring capacity and broad host range.

An algorithm for computerized automatic tuning of power system stabilizers

The main objective of this paper is to relieve the power system engineers from the burden of the complex and time-consuming process of power system stabilizer (PSS) tuning. To achieve this goal, the paper proposes an automatic process for computerized tuning of PSSs, which is based on an iterative process that uses a linear matrix inequality (LMI) solver to find the PSS parameters. It is shown in the paper that PSS tuning can be written as a search problem over a non-convex feasible set. The proposed algorithm solves this feasibility problem using an iterative LMI approach and a suitable initial condition, corresponding to a PSS designed for nominal operating conditions only (which is a quite simple task, since the required phase compensation is uniquely defined). Some knowledge about the PSS tuning is also incorporated in the algorithm through the specification of bounds defining the allowable PSS parameters. The application of the proposed algorithm to a benchmark test system and the nonlinear simulation of the resulting closed-loop models demonstrate the efficiency of this algorithm. (C) 2009 Elsevier Ltd. All rights reserved.

Comparative analysis of triple band S-C-L erbium-doped fibre and semiconductor optical amplifier for CWDM applications

The authors present a comparative analysis between a triple-band S-C-L erbium-doped fibre amplifier and a commercial semiconductor optical amplifier in a CWDM application scenario. Both technologies were characterised for gain and noise figures from 1480 to 1610 nm (S, C and L bands) and their systemic performances were evaluated in terms of bit error rate measurements for a wide range of optical power levels.

Active sound quality control of engine induced cavity noise

Active control solutions appear to be a feasible approach to cope with the steadily increasing requirements for noise reduction in the transportation industry. Active controllers tend to be designed with a target on the sound pressure level reduction. However, the perceived control efficiency for the occupants can be more accurately assessed if psychoacoustic metrics can be taken into account. Therefore, this paper aims to evaluate, numerically and experimentally, the effect of a feedback controller on the sound quality of a vehicle mockup excited with engine noise. The proposed simulation scheme is described and experimentally validated. The engine excitation is provided by a sound quality equivalent engine simulator, running on a real-time platform that delivers harmonic excitation in function of the driving condition. The controller performance is evaluated in terms of specific loudness and roughness. It is shown that the use of a quite simple control strategy, such as a velocity feedback, can result in satisfactory loudness reduction with slightly spread roughness, improving the overall perception of the engine sound. (C) 2008 Elsevier Ltd. All rights reserved.

Stability analysis of core-annular flow and neutral stability wave number

A general transition criterion is proposed in order to locate the core-annular flow pattern in horizontal and vertical oil-water flows. It is based on a rigorous one-dimensional two-fluid model of liquid-liquid two-phase flow and considers the existence of critical interfacial wave numbers related to a non-negligible interfacial tension term to which the linear stability theory still applies. The viscous laminar-laminar flow problem is fully resolved and turbulence effects on the stability are analyzed through experimentally obtained shape factors. The proposed general transition criterion includes in its formulation the inviscid Kelvin-Helmholtz`s discriminator. If a theoretical maximum wavelength is considered as a necessary condition for stability, a stability criterion in terms of the Eotvos number is achieved. Effects of interfacial tension, viscosity ratio, density difference, and shape factors on the stability of core-annular flow are analyzed in detail. The more complete modeling allowed for the analysis of the neutral-stability wave number and the results strongly suggest that the interfacial tension term plays an indispensable role in the correct prediction of the stable region of core-annular flow pattern. The incorporation of a theoretical minimum wavelength into the transition model produced significantly better results. The criterion predictions were compared with recent data from the literature and the agreement is encouraging. (C) 2007 American Institute of Chemical Engineers.

Contribution to dynamic characteristics of the cutting temperature in the drilling process considering one dimension heat flow

The machining of hardened steels has always been a great challenge in metal cutting, particularly for drilling operations. Generally, drilling is the machining process that is most difficult to cool due to the tool`s geometry. The aim of this work is to determine the heat flux and the coefficient of convection in drilling using the inverse heat conduction method. Temperature was assessed during the drilling of hardened AISI H13 steel using the embedded thermocouple technique. Dry machining and two cooling/lubrication systems were used, and thermocouples were fixed at distances very close to the hole`s wall. Tests were replicated for each condition, and were carried out with new and worn drills. An analytical heat conduction model was used to calculate the temperature at tool-workpiece interface and to define the heat flux and the coefficient of convection. In all tests using new and worn out drills, the lowest temperatures and decrease of heat flux were observed using the flooded system, followed by the MQL, considering the dry condition as reference. The decrease of temperature was directly proportional to the amount of lubricant applied and was significant in the MQL system when compared to dry cutting. (C) 2011 Elsevier Ltd. All rights reserved.

Simplified models for cross-section stress demands on C-section purlins in uplift

The objective of this paper is to provide and verify simplified models that predict the longitudinal stresses that develop in C-section purlins in uplift. The paper begins with the simple case of flexural stress: where the force has to be applied at the shear center, or the section braced in both flanges. Restrictions on load application point and restraint of the flanges are removed until arriving at the more complex problem of bending when movement of the tension flange alone is restricted, as commonly found in purlin-sheeting systems. Winter`s model for predicting the longitudinal stresses developed due to direct torsion is reviewed, verified, and then extended to cover the case of a bending member with tension flange restraint. The developed longitudinal stresses from flexure and restrained torsion are used to assess the elastic stability behavior of typical purlin-sheeting systems. Finally, strength predictions of typical C-section purlins are provided for existing AISI methods and a newly proposed extension to the direct strength method that employs the predicted longitudinal stress distributions within the strength prediction. (C) 2009 Elsevier Ltd. All rights reserved.

Study of partially encased composite beams with innovative position of stud bolts

In this article, static behavior of three partially encased composite beams under flexural condition is investigated in the context of studying some alternative positions for the headed studs. Shear resistance between the I-shaped beam and the concrete was provided by headed studs in two positions: vertically welded oil the bottom flange and horizontally welded on the faces of the web. Experimental results show that the headed studs provide the composite action and increase the bending strength. The most remarkable position seems to be the headed studs vertically welded oil the bottom flange. Ail analytical method to estimate the bending capacity of the encased beams is also proposed, giving a good prediction of the experimental results (C) 2008 Elsevier Ltd. All rights reserved.

Influence of carbon sources and C/N ratio on EPS production in anaerobic sequencing batch biofilm reactors for wastewater treatment

The objective of this work was to evaluate the influence of different carbon sources and the carbon/nitrogen ratio (C/N) on the production and main composition of insoluble extracellular polymers (EPS) produced in an anaerobic sequencing batch biofilm reactor (ASBBR) with immobilized biomass in polyurethane foam. The yield of EPS was 23.6 mg/g carbon, 13.3 mg/g carbon, 9.0 mg/g carbon and 1.4 mg/g carbon when the reactor was fed with glucose, soybean oil. fat acids, and meat extract, respectively. The yield of EPS decreased from 23.6 to 2.6 mg/g carbon as the C/N ratio was decreased from 13.6 to 3.4 gC/gN, using glucose as carbon source. EPS production was not observed under strict anaerobic conditions. The results suggest that the carbon source, microaerophilic conditions and high C/N ratio favor EPS production in the ASBBR used for wastewater treatment. Cellulose was the main exopolysaccharide observed in all experimental conditions. (C) 2009 Elsevier Ltd. All rights reserved.

An upflow fixed-bed anaerobic-aerobic reactor for removal of organic matter and nitrogen from L-lysine plant wastewater

This paper reports on the design of a new reactor configuration - an upflow fixed-bed combined anaerobic-aerobic reactor - can operate as a single treatment unit for the removal of nitrogen (approximate to 150 mg N/L) and organic matter (approximate to 1300 mg COD/L) from Lysine plant wastewater. L-Lysine, an essential amino acid for animal nutrition, is produced by fermentation from natural raw materials of agricultural origin, thus generating wastewater with high contents of organic matter and nitrogen. The best operational condition of the reactor was obtained with a hydraulic retention time of 35 h (21 h in the anaerobic zone and 14 h in the aerobic zone) and a recycling ratio (R) of 3.5. In this condition, the COD, total Kjeldahl nitrogen (TKN), and total nitrogen (TN) removal efficiencies were 97%, 96%, and 77%, respectively, with average effluent concentrations of 10 +/- 36 mg COD/L, 2 +/- 1 mg NH(4)(+)-N/L, 8 +/- 3 mg Org-N/L, 1 +/- 1 mg NH(2)(-)-N/L, and 26 +/- 23 mg NH(3)(-)-N/L.

Feasibility of a Sequencing Reactor Operated in Batch and Fed-batch Mode Applied to Nitrification and Denitrification Processes

The objective of this work was to study the operational feasibility of nitrification and denitrification processes in a mechanically stirred sequencing batch reactor (SBR) operated in batch and fed-batch mode. The reactor was equipped with a draft-tube to improve mass transfer and contained dispersed (aerobic) and granulated (anaerobic) biomass. The following reactor variables were adjusted: aeration time during the nitrification step; dissolved oxygen concentration, feed time defining batch and fed-batch phases, concentration of external carbon source used as electron donor during the denitrification stage and volumetric ammonium nitrogen load in the influent. The reactor (5 L volume) was maintained at 30 +/- 1 degrees C and treated either 1.0 or 1.5 L wastewater in 8-h cycles. Ammonium nitrogen concentrations assessed were: 50 (condition 1) and 100 mgN-NH(4)(+).L(-1) (condition 2), resulting in 29 and 67 mgN-NH(4)(+).L-1-d(-1), respectively. A synthetic medium and ethanol were used as external carbon sources (ECS). Total nitrogen removal efficiencies were 94.4 and 95.9% when the reactor was operated under conditions 1 and 2, respectively. Low nitrite (0.2 and 0.3 mgN-NO(2)(-).L(-1), respectively) and nitrate (0.01 and 0.3 mgN-NO(3)(-).L(-1), respectively) concentrations were detected in the effluent and ammonium nitrogen removal efficiencies were 97.6% and 99.6% under conditions 1 and 2, respectively.

Design and Characterization of Novel Wear Resistant Multilayer CVD Coatings with Improved Adhesion Between Al(2)O(3) and Ti(C,N)

Multilayer CVD coatings for high speed cutting applications were designed to achieve high wear and heat resistance during machining of steel alloys. In this work the microstructure and cutting performance of these novel multilayer CVD coatings are investigated and compared with standard CVD multilayer coatings. 3D-FIB tomography is used to characterize the microstructure of the layers, especially the transition between the Ti(C,N) and the Al(2)O(3) layer. The 3D reconstruction of the surface of the Ti(C,N) layer shows the formation of protruded Ti(C,N) grains with a very particular architecture, which penetrate into the Al(2)O(3) top-layer, providing a mechanical anchoring between both layers. Cemented carbides coated with the novel CVD multilayer present reduced crater and flank wear as well as improved adherence between the Al(2)O(3) top-layer and the Ti(C,N) layer leading to a dramatic improvement of cutting performance.

Effect of binders and surface finish on wear resistance of HVOF coatings

The high velocity oxygen fuel (HVOF) thermal spray process produces highly wear and/or corrosion resistant coatings. Tungsten carbide with a metallic binder is often used for this purpose. In this work, tungsten carbide coatings containing cobalt or nickel binder were produced by HVOF and characterised by optical and electron microscopy, hardness and a dry sand/rubber wheel abrasion test. The HVOF process produced dense coatings with low porosity levels and high hardness. The wear resistance of the specimens, which were surface treated, increased as the roughness percentage decreased. Tungsten carbide nickel based coating yielded the best wear resistance in the as sprayed condition. However, the wear rate and wear of the two coatings converged to the same values as the number of revolutions increased. Wear behaviour in the ground condition was similar, although the tungsten carbide cobalt based coating yielded better performance with increasing distance travelled during the wear test.

Crystallisation behaviours of Al-based metallic glasses: Compositional and topological aspects

The different types of thermal crystallisation behaviours observed during continuous heating of M-based metallic glasses have been successfully associated with the topological instability. criterion, which is simply calculated from the alloy composition and metallic radii of the alloying elements and aluminium. In the present work, we report on new results evidencing the correlation between the values of X and the crystallisation behaviours in Al-based alloys of the Al-Ni-Ce system and we compare the glass-forming abilities of alloys designed with compositions corresponding to the same topological instability condition. The results are discussed in terms of compositional and topological aspects emphasizing the relevance of the different types of clusters in the amorphous phase in defining the stability of the glass and the types of thermal crystallisation. (C) 2008 Elsevier B.V. All rights reserved.

Sigma phase morphologies in cast and aged super duplex stainless steel

Solution annealed and water quenched duplex and super duplex stainless steels are thermodynamically metastable systems at room temperature. These systems do not migrate spontaneously to a thermodynamically stable condition because an energy barrier separates the metastable and stable states. However, any heat input they receive, for example through isothermal treatment or through prolonged exposure to a voltaic arc in the welding process, cause them to reach a condition of stable equilibrium which, for super duplex stainless steels, means precipitation of intermetallic and carbide phases. These phases include the sigma phase, which is easily identified from its morphology, and its influence on the material`s impact strength. The purpose of this work was to ascertain how 2-hour isothermal heat treatments at 920 degrees C and 980 degrees C affect the microstructure of ASTM A890/A890M GR 6A super duplex stainless steel. The sigma phase morphologies were found to be influenced by these two aging temperatures, with the material showing a predominantly lacy microstructure when heat treated at 920 degrees C and block-shaped when heat treated at 980 degrees C. (C) 2009 Elsevier Inc. All rights reserved.