The role of environmental feedback in a brain state switch from passive to active sensing

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Optimal distribution of active piezoelectric elements for noise attenuation in sandwich panels

In this paper, a multiobjective optimization approach for obtaining the optimal distribution of surface-bonded piezoelectric sensors and actuators for noise attenuation in sandwich panels is presented. The noise attenuation is achieved by using negative velocity feedback control with co-located sensors and actuators. The control gains are also optimized in order to obtain the most efficient noise attenuation in a given frequency band. An in-house implementation of a viscoelastic soft core sandwich plate finite element, including surface-bonded piezoelectric sensors and actuators with active control capabilities, is used for obtaining the frequency response of the panels. The sound transmission capability of the panels is evaluated using the radiated sound power, along with the Rayleigh integral approach, which is suitable for lightly coupled structural/acoustic problems. The Direct MultiSearch (DMS) optimization algorithm is used to minimize the added weight due to the piezoelectric material, minimizing also the number of required controllers and maximizing the noise attenuation. The total length of the radiated sound power curve is shown to be an effective measure of noise attenuation in a given frequency band. Trade-off Pareto fronts and the obtained optimal configurations are presented and discussed.info:eu-repo/semantics/publishedVersio

Retinoblastoma - a clinico - pathological study in Ilorin, Nigeria

Retinoblastoma is the commonest childhood primary malignant intraocular neoplasm that is often characterized by spontaneous regression. They display photoreceptor differentiation. This study provides the clinical presentations and histological profiles of retinoblastoma in Ilorin, Kwara – State, in the North Central geo-political zone of Nigeria. A retrospective study of clinically and histologically verified retinoblastoma at the University of Ilorin Teaching Hospital, Ilorin, Kwara – State, Nigeria from January 1989 to December 2000 was undertaken. The clinical and histological features were analyzed using the patient\'s case folder and surgical pathology records. There were 20 patients, 9 males and 11 females (M:F ratio 1: 1.2), age range from 5 1/2 months to 6 years with 23 eyeball tumours histologically confirmed retinoblastoma during the study period. Proptosis with chemosis was the most common clinical presentation (84.6%). Bilaterality was 15% in this study. Enucleation and Exenteration combined with chemotherapy were offered to 15 (75%) and 5 (25%) patients respectively. A poorly differentiated type with extensive areas of tumour necrosis was the commonest histological pattern. Thirteen (65%) of the patients died before completing the course of chemotherapy. African Journal of Health Sciences Vol. 13 (1-2) 2008: pp. 117-12

Comparison of fouling of raw milk and whey protein solution on stainless steel and fluorocarbon coated surfaces: Effects on fouling performance, deposit structure and composition

Fouling from raw milk and from whey protein solutions mimicking the protein content of milk have been performed at two length scales, using a microfluidic heat transfer cell and a bench-scale device with hydraulic diameters 1:0mm and 16:1 mm, respectively. The microfluidic cell allows raw milk to be studied in once-through mode and was used to identify polymer coated surfaces to test against stainless steel. Several of the fluorocarbon coated surfaces reduced the mass deposition but the pressure drop and thermal resistance did not match these directly, indicating that the nature and structure of the deposit is affected by the surface. A fluorinated ethylene propylene coating was identified as a promising candidate for large scale tests. At the interface with apolar surfaces, raw milk fouling layers were high in protein whereas a strongly attached mineral-rich layer was present at the interface with steel. The attraction of denatured protein towards apolar surfaces and the formation of a calcium phosphate layer on steel at later stages of fouling are explained with arguments based on the interfacial free energy of these materials in water.The work was funded by Chemours Belgium BVB

Comparative Analysis of the Financial Performance of Provincial Governments in Sulawesi for the 2012-2015 Period

The results of the calculation of the Degree Ratio of Fiscal Decentralization for the Provincial Government (Pemprov) of North Sulawesi (Sulut) show a relatively good trend compared to most provinces in Sulawesi. In the 2012-2015 range, the North Sulawesi Provincial Government was in the category of Sufficient financial capability (2012-2013) and rose to the Medium category (2014-2015). Gorontalo Province, in the span of the same year, in the Ratio of Degrees of Fiscal Decentralization, was still in the Very Poor Regional Financial Capability Category in 2012 and Less in the following years. The Province of Central Sulawesi (Sulteng) shows an up and down trend in the Degree Ratio of Fiscal Decentralization. In 2012, Central Sulawesi was included in the Poor category in its ability to increase local revenue to finance development. In 2013 the province managed to move up to the Enough category (31. 07%) and decreased by a level in 2014 and returned to the Enough category in 2015 with a ratio of 30.78%. Southeast Sulawesi Province, in the 2012-2015 period, was in the same category in its ability to increase local revenue to finance development. Southeast Sulawesi is in the Less category with the highest achievement in 2015 at a ratio of 27.68%. South Sulawesi Province (Sulsel) is the province that has the best Fiscal Decentralization Degree Ratio performance relative to other provinces in Sulawesi. In 2012, the performance of South Sulawesi's Fiscal Decentralization Degree Ratio stood at 49.59% in the Medium category and increased in the 2013-2015 range which remained in the Good category. This is the only province that has a Fiscal Decentralization Ratio with a Good category. The level of dependence of the Province of South Sulawesi on external assistance is very low and vice versa. The South Sulawesi Regional Financial Independence Ratio also proves the high level of community participation in regional development

Numerical study of fatigue crack initiation and propagation on optimally designed cruciform specimens

A new generation of smaller and more efficient biaxial fatigue testing machines has arrived on the market. Using electrical motors these machines are not able to achieve the higher loads their hydraulic counterparts can, and therefore the cruciform specimen needs to be optimized Following the authors previous work, several different optimal specimens' configurations were produced, using the base material sheet thickness as the main design variable. Every design variable was optimized in order to produce the highest stress level on the specimen center, while the stress distribution is still uniform on a 1 mm radius of the specimen center. Also it was guaranteed that the stress level on the specimen arms was always considerably lower, in order to achieve failure at the specimen center. In this paper traditional criteria like Findley, Brown-Miller, Fatemi-Socie, Smith, Watson e Topper (SWT), Liu I and Chu were considered to determine crack initiation direction for several loads in this biaxial in-plane specimens. In order to understand the fatigue propagation behavior, the stress intensity factors for mode I and mode II was determined for different cracks introduced on the geometry. Several crack and loading parameters were studied, including the starting crack length and angle, and different loading paths. Several biaxial loads were applied to the model, including 30, 45, 60, 90 and 180 out-of-phase angles.info:eu-repo/semantics/publishedVersio

Surgical correction of scoliosis: Numerical analysis and optimization of the procedure

A previously developed model is used to numerically simulate real clinical cases of the surgical correction of scoliosis. This model consists of one-dimensional finite elements with spatial deformation in which (i) the column is represented by its axis; (ii) the vertebrae are assumed to be rigid; and (iii) the deformability of the column is concentrated in springs that connect the successive rigid elements. The metallic rods used for the surgical correction are modeled by beam elements with linear elastic behavior. To obtain the forces at the connections between the metallic rods and the vertebrae geometrically, non-linear finite element analyses are performed. The tightening sequence determines the magnitude of the forces applied to the patient column, and it is desirable to keep those forces as small as possible. In this study, a Genetic Algorithm optimization is applied to this model in order to determine the sequence that minimizes the corrective forces applied during the surgery. This amounts to find the optimal permutation of integers 1, ... , n, n being the number of vertebrae involved. As such, we are faced with a combinatorial optimization problem isomorph to the Traveling Salesman Problem. The fitness evaluation requires one computing intensive Finite Element Analysis per candidate solution and, thus, a parallel implementation of the Genetic Algorithm is developed

Adhesion and cleaning of foods with complex structure: Effect of oil content and fluoropolymer coating characteristics on the detachment of cake from baking surfaces

The effect of surface coating on the detachment of a complex microstructured food material, was investigated using an improved version of the millimanipulation device described by Ali et al. (2015 \textit{Food & Bioproducts Processing}, Vol. 93, 256–268). The test material was baked sponge cake batter, which contains approximately 27 vol% bubbles in a ‘continuous’ phase of emulsified oil in a flour/syrup suspension. Detachment in the dry state was studied for aluminium, 304 stainless steel and seven different fluoropolymer coatings. The surfaces differed in surface energy and roughness. The shear force required to detach baked cake, the work done, and the mass of residue remaining on the surface were measured. Virtually all samples detached by cohesive or mixed failure, where adhesion to the surface was stronger than or comparable with cohesive interactions within the cake. The shear force was almost independent of surface composition, energy and roughness, but strongly related to the oil content of the cake. The mass of residue was found to be linearly dependent on the calculated work of adhesion of oil to the surface in an aqueous environment. The quantitative findings are consistent with confocal microscopy images of uncooked batter contacting polar and non-polar surfaces which show very different oil spreading behaviour at the batter-substrate interface. The ability of oil to replace water from a surface is shown to be a key factor determining adhesion of these materials.A Jardine Postgraduate Scholarship for YL from the Jardine Foundation and a PhD studentship for OMM from Du Pont/Chemours and is gratefully acknowledged