Optimal improvement in bistable measurement device performance via stochastic resonance

The notion of noise-activated systems has been well known since the 1950s. A number of natural phenomena have been investigated by means of this theory and an improvement in the performance of several systems has also been achieved. Recently the stochastic resonance (SR) phenomenon was introduced as an innovative approach for both understanding the behaviour and improving the performance of several classes of systems. In the present work some new results regarding the influence of forcing signal parameters on the persistence of the SR condition are given. Both theoretical results and numerical simulations have been carried out to emphasize the suitability of the proposed noise tuning methodology.     

The design of servomechanism controllers for uncertain plants

The design of multivariable servomechanism controllers is considered here for plants whose parameters are uncertain or perturbed within a cone-bounding criterion. The solution comes from a controller design problem as an LQ optimal control problem in which the gain matrices result in a quadratic performance upper bound (similar to that described by Gilman and Rhodes (1976() which depends on the uncertainty. Under conditions on the nominal plant and on the uncertainty, a resulting linear time-invariant controller is guaranteed to achieve the objectives of robust tracking and regulation with closed-loop stability.     

BITTER TASTE AND PHENOLIC COMPOUNDS IN EXTRA VIRGIN OLIVE OIL: AN EMPIRICAL RELATIONSHIP

Bitter taste of extra virgin olive oil is known to be affected by the phenolic composition. However, contribution of each individual phenol to this sensory note has not been clearly defined. The aims of this study were to verify whether there was a relationship between bitter sensation and phenolic compound concentration, to determine which compounds were involved in bitter taste and to evaluate quantitatively this correlation. Results confirmed that a positive correlation did exist between total phenolic amount and bitter intensity. Data processing showed that this correlation was significantly dependent upon a relationship between oleuropein aglycon (3,4‐DHPEA‐EA) and bitter intensity. An empirical exponential model was set up and validated.     

Vascular function in berries of Vitis vinifera (L) cv. Shiraz

Anatomical studies on the movement of a xylem tracer dye were combined with functional studies on changes in grape berry volume during final stages of berry ripening to gauge xylem effectiveness. Movement of a xylem tracer dye into pre-veraison fruit was compared with movement into post-veraison fruit by feeding a solution of acid fuchsin to excised shoots with bunches still attached, and then sectioning fruit for photo-microscopy. Those comparisons confirmed published studies showing an apparent blockage to dye movement along major vessels within the brush tissue of post-veraison fruit. However, our functional approach yielded a different impression of vascular activity. A continuation of xylem transport in ripening fruit was inferred from comparisons of berry volume where pedicels were either girdled (phloem interrupted, but xylem intact) or excised (both phloem and xylem interrupted). Volume changes in manipulated berries were compared with immediately adjacent intact control berries within the same bunch. Control fruit lost volume subsequent to 78 days after flowering (DAF) while manipulated fruit lost volume from the first day of treatment at 67 DAF. By harvest time at 95 DAF, both control fruit and girdled fruit had fallen to 91% and excised fruit to 46% of maximum volumes recorded around 78 DAF. Berry volume loss in girdled fruit was further enhanced by deficit irrigation. We conclude that xylem flow into those Shiraz berries must have continued beyond veraison despite dye evidence of a vessel blockage within the brush region of analogous post-veraison fruit.     

Geographies of whiteness and wealth: White,middle class discourses on segregation and social mix in Flanders,Belgium

While policy makers in different parts of the world are worried about the supposedly negative consequences of spatial concentrations of ethnic minorities and/or disadvantaged people, researchers continue the debate about the desirability and feasibility of social mix. In this article, we add to this literature by focusing on the often neglected, but crucial practices and discourses of the privileged in urban and suburban neighborhoods. Drawing on in‐depth interviews with 74 white, middle class residents of eight different neighborhoods of the Ghent urban region in Belgium, we demonstrate that few middle class whites actually want to live in a mixed neighborhood. We also make it clear that those living in diversity do not necessarily take up the roles they are expected to take up by the advocates of social mix policies. Drawing on these findings, we propose to broaden the research agenda of studies on segregation and social mix.     

Formulation and rheological characterization of reduced-calorie food emulsions

Water-in-oil-in-water (W/O/W) double emulsions are systems where a water-in-oil emulsion (W/O) is dispersed in a second aqueous phase. The W/O emulsion exists in the suspending aqueous medium as oil globules containing smaller water droplets.
In this work, a selection of both materials and procedures has been made in order to obtain an optimal formulation of a W/O/W food emulsion for both yield and rheologica] properties.
The rheological properties of W/O/W emulsions have been studied by means of both steady-shear and oscillatory measurements, and appeared to be similar to those of a simple O/W emulsion having the same volume fraction of dispersed phase, but lower oil content.
This is of great interest to the food industry, since producing double emulsions with the same texture as simple ones, but a lower oil content, helps to formulate reduced-calorie foods.     

Aerodynamic Behavior of Long-Span Cable-Stayed Bridges

In this paper, we study the behavior of the aerodynamic fan-shaped scheme of cable-stayed bridges under wind load. A numerical analysis is developed, based upon time integration of the motion equations of the discretized structure. The main structural nonlinearity arising from the stress–strain stay's constitutive equation is taken into account together with the nonlinear effects that arise assuming a nonstationary model for aerodynamic loads. A Newmark's type algorithm is used to discuss first the problem of free oscillations in still air, and to determine next the critical wind speeds, both in the case of A-shaped and of H-shaped towers. For the latter case, the overall discrete model is validated by comparison with analytical results obtained by a continuous model, already developed [5, 7]. The performance improvement of the structural behavior obtained by using A-shaped towers is numerically investigated by using the discrete model proposed here.     

COLLEGE-BASED HUMAN SERVICE STAFF TRAINING: NEEDS,OPPORTUNITIES AND RESOURCES

This paper describes and illustrates the broad range of needs, opportunities, and community resources that exist for the initiation and development by colleges and universities of in-service and continuing education programs for a variety of human service personnel. In addition to describing the processes involved and the problems encountered in responding effectively to the widely divergent educational needs of the various types of personnel who staff the human services, this paper identifies some of the issues that must be addressed by any college or university that seeks to provide this type of educational service.     

The design of servomechanism controllers for uncertain plants and input signals

This paper summarizes a methodology for the design of servomechanism controllers for multivariate plants and reference/disturbance signals which may be uncertain or weakly non-linear. This framework represents a departure from the idealized tracking/disturbance rejection problem in the direction of realistic design considerations. The objective becomes ‘good’, though not exact, error regulation for applied signals which may be unknown or random in nature.     

Sprayed CdS-Cu2S Solar Cells 1—Formation of Cuprous Sulphide

The formation of cuprous sulphide by ion exchange ( “dipping”) on CdS spray was studied by analysing its thickness and deviation from stoichiometry. Factorial analysis was used to diminish the effects of substrate variability. A stable solution for ion exchange is described. The significance of the influence of temperature and duration of reaction as well as the concentration of Cu(I) in solution is noted. A model representing the growth of Cu_S and permitting the chracteristics of CdS to be transformed into Cu₂S is given. Improving the quality of CdS measured in this way diminished the influence of the above parameters.