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.

Feasibility of Electronic Tap-Changing Stabilizers for Medium Voltage Lines-Precedents and New Configurations

Thyristor-based onload tap-changing ac voltage stabilizers are cheap and robust. They have replaced most mechanical tap-changers in low voltage applications from 300 VA to 300 M. Nevertheless, this replacement hardily applies to tap-changers associated to transformers feeding medium-voltage lines (typically 69 kV primary, 34.5 kV line, 10 MVA) which need periodical maintenance of contacts and oil. The Electric Power Research Institute (EPRI) has studied the feasibility of this replacement. It detected economical problems derived from the need for series association of thyristors to manage the high voltages involved, and from the current overload developed under line fault. The paper reviews the configurations used in that field and proposes new solutions, using a compensating transformer in the main circuit and multi-winding coils in the commutating circuit, with reduced overload effect and no series association of thyristors, drastically decreasing their number and rating. The stabilizer can be installed at any point of the line and the electronic circuit can be fixed to ground. Subsequent works study and synthesize several commutating circuits in detail.

Simulated annealing with adaptive neighborhood: A case study in off-line robot path planning

Simulated annealing (SA) is an optimization technique that can process cost functions with degrees of nonlinearities, discontinuities and stochasticity. It can process arbitrary boundary conditions and constraints imposed on these cost functions. The SA technique is applied to the problem of robot path planning. Three situations are considered here: the path is represented as a polyline; as a Bezier curve; and as a spline interpolated curve. In the proposed SA algorithm, the sensitivity of each continuous parameter is evaluated at each iteration increasing the number of accepted solutions. The sensitivity of each parameter is associated to its probability distribution in the definition of the next candidate. (C) 2010 Elsevier Ltd. All rights reserved.

Economic feasibility of cowpea irrigation in Piaui State

The objective of this work was to evaluate the economic feasibility of cowpea irrigation in Piaui State Brazil. Water balances were carried out on a daily basis using the Thornthwaite and Mather (1955) method, for 165 sites, considering twelve sowings dates and available water capacity in the soil of 20, 40 and 60 mm. The net revenues were estimated with a probability of occurrence of 75%, later being spatialized to Piaui State. Cowpea irrigation was shown to economically viable for all sowing dates, irrespective of the available water capacity. Net revenues varied among several regions of the State, in function of the sowing date and available water capacity in the soil. Considering a planning strategy for Piaui State, sowing on February, I was shown to be most favorable, because it enabled higher net revenue values, covering larger areas of the State.

Does using stepwise variable selection to build sequential path analysis models make sense?

Causal inference methods - mainly path analysis and structural equation modeling - offer plant physiologists information about cause-and-effect relationships among plant traits. Recently, an unusual approach to causal inference through stepwise variable selection has been proposed and used in various works on plant physiology. The approach should not be considered correct from a biological point of view. Here, it is explained why stepwise variable selection should not be used for causal inference, and shown what strange conclusions can be drawn based upon the former analysis when one aims to interpret cause-and-effect relationships among plant traits.

Thesis summary: Standardized dried extracts of Brazilian medicinal plants: Assessment of technical and economic feasibility of spouted bed drying

This study is an integral part of a research project which seeks the establishment of protocols for the production of standardized herbal dried extracts emphasizing the spouted bed drying. This thesis was conducted at faculty of Pharmaceutical Science of Ribeiro Preto/University of So Paulo, Brazil, under supervision of Prof. Dr. Wanderley Pereira Oliveira*, defended on September 28, 2007.

The Genetic Speciation of Archaeological Fish Bone: A Feasibility Study from Southeast Queensland

Current genetic methods enable highly specific identification of DNA from modern fish bone. The applicability of these methods to the identification of archaeological fish bone was investigated through a study of a sample from late Holocene southeast Queensland sites. The resultant overall success rate of 2% indicates that DNA analysis is, as yet, not feasible for identifying fish bone from any given site. Taphonomic issues influencing the potential of genetic identification methods are raised and discussed in light of this result.

The design of planar gradient coils. Part I: A winding path correction method

In this work a new approach for designing planar gradient coils is outlined for the use in an existing MRI apparatus. A technique that allows for gradient field corrections inside the diameter-sensitive volume is deliberated. These corrections are brought about by making changes to the wire paths that constitute the coil windings, and hence, is called the path correction method. The existing well-known target held method is used to gauge the performance of a typical gradient coil. The gradient coil design methodology is demonstrated for planar openable gradient coils that can be inserted into an existing MRI apparatus. The path corrected gradient coil is compared to the coil obtained using the target field method. It is shown that using a wire path correction with optimized variables, winding patterns that can deliver high magnetic gradient field strengths and large imaging regions can be obtained.

Use of Acoustic Doppler Sonography to Ascertain the Feasibility of the Pedicled Nasoseptal Flap After Prior Bilateral Sphenoidotomy

Objectives/Hypothesis: Blood supply to the Hadad-Bassagasteguy pedicled nasoseptal flap may be interrupted by surgery of the pterygopalatine fossa, posterior septectomy, or large sphenoidotomies. This would preclude its use for reconstruction of skull base defects after expanded endonasal approaches (EEA). We present a novel method to ascertain the patency of the nasoseptal artery after prior surgery, and consequently the availability of the nasoseptal flap, using acoustic Doppler sonography. Study Design: Retrospective clinical review. Methods: Four patients who underwent EEAs were evaluated intraoperatively with acoustic Doppler sonography. The mucosa that covers the inferior aspect of the rostrum of the sphenoid sinus was scanned with the tip of the probe. Reflection of sound waves representing intravascular blood flow was assessed. Results: In three patients, the artery was identified in at least one side. One remaining patient showed no acoustic signal suggesting loss of the nasoseptal artery bilaterally, therefore necessitating the use of a fat graft for the reconstruction. Conclusions: Acoustic Doppler sonography seems to be a feasible and effective way to ascertain the availability of the nasoseptal artery. It is a relatively inexpensive and simple technique that can be performed by any endoscopic surgeon.

A randomized double-blind placebo-controlled trial to increase feasibility of dobutamine stress echocardiography in patients with hypertension

Objective: To increase dobutamine stress echocardiography feasibility in patients with uncontrolled hypertension, we studied 729 consecutive patients referred for ischemia assessment. Methods: Patients with blood pressure ( BP) levels above 160/ 110 mm Hg were randomized to sublingual placebo or captopril ( 25 mg), and dobutamine stress echocardiography undertaken if BP decreased below 160/ 110 mm Hg after 15 minutes. Results: Of 149 patients ( 20%) with high BP levels, 104 ( 63 +/- 11 years, 51 male) were randomized. Baseline BP levels were similar for captopril ( 178 +/- 15/ 103 +/- 15 mm Hg) and placebo ( 181 +/- 17/ 103 +/- 15 mm Hg) groups. After intervention, 15 patients from captopril and 17 from placebo group had decreased BP ( 11% and 12% for systolic and 13% and 13% for diastolic BP, respectively). Five patients from placebo group ( P =.007) had to prematurely terminate the test because of hypertension ( BP > 220/ 120 mm Hg). Feasibility was similar for captopril and placebo groups ( 35% vs 25%, respectively, P = not significant). Conclusion: Although both captopril and placebo are effective in increasing dobutamine stress echocardiography feasibility in patients with uncontrolled BP, test interruption because of hypertension is less likely to occur after captopril administration.