Optical nonlinearities at the interface between liquid crystal and glass: behavior of the transmitted beam.

During the past years a great interest has been devoted to the study of possible applications of non-linear interfaces, mainly in the field of Optical Bistability. Several papers have been published in this field, and some of them dealing with liquid crystals as non-linear material.

New non-reorientational, non-thermal optical nonlinear effect in MBBA

It is widely known the anular-shaped beam divergence produced by the optical reorientation induced in nematics by a Gaussian beam. Recent works have found a new effect in colored liquid crystal (MBBA, Phase V,...) showing a similar spatial distribution. A new set of random-oscillating rings appears for light intensities over a certain threshold. The beam divergence due to that effect is greater than the molecular reorientation induced one.

Effects of precooling and degreening treatments on the susceptibility of peach and citrus to handling damage.

Mechanical damage to fruits results from a combination of fruit properties and of damage inflicting effects by the handling equipment. Treatments were applied to fruits which affect mechanical damage susceptibility: precooling for stone fruits and degreening to citrus fruits. Laboratory tests (compression, impact, tumbling, abrasion) and field tests (damage in the handling lines) were applied to (3) peach, (2) apricot, (2) orange and (1) lemon varieties. Hydroor-air-cooling influence positively peach and apricot firmness and cause a significant reduction in: number of bruised fruits, and size of visible bruise, when combined with a low level of loading during handling. Degreening also affects the resistance of citrus fruits to handling, when compared to green fruits.

Models for the prediction of handling damage in citrus and peaches grading lines, related to their physical properties.

Fruit damage during harvesting and handling is a standing problem, particularly for susceptible fruits like peaches and apricots. The resulting mechanical damage is a combination of fruit properties and damage inflicting effects due to procedures and to the equipment. Nine packing lines in the region of Murcia (SE Spain) have been tested with the aid of two different-size electronic fruits IS-100. Probabilities of impacts above three preset thresholds (50 g's, 100 g's and 150 g's) were calculated for each transfer point. Interaction fruit-packing line tests have been also performed in order to study the real incidence of packing lines on natural produce: apricots (1 variety), peaches (3 v.), lemons (1 v.) and oranges (3 v.). Bruises of handled and not handled samples of fruits were compared.

Nonlinear interface behavior between glass and liquid crystal

As has been shown in the literature, an interface between two dielectric materials, one of which has an intensity-dependent refractive index is capable of exhibing a wide range of complex and potentially useful optical phenomena.

Analysis of punching of a reinforced concrete slab within IRIS_2012

As part of the IRIS_2012 international benchmark, simulations were conducted to analyse impacts on reinforced concrete slabs by both rigid and deformable missiles. The analytical results were compared with physical tests conducted by the Technical Research Center VTT of Finland. In the impact discussed here, a rigid missile perforates the concrete slab. The missile is a thick steel tube filled with concrete with a total mass of 47.4 kg and strikes the target at 136 m/s. The target is a 250 mm thick, reinforced concrete slab that spans 2 m by 2 m and is held in a rigid supporting frame. Characterisation tests were provided for calibration of the parameters of the concrete models selected by the participants. Having reproduced those tests, the authors developed models for the slab and the missile. A damaged plasticity model was used for the concrete and the rebars were explicitly represented. The results obtained were very satisfactory in respect of the damage patterns caused in the concrete and the reinforcement; also, the calculated and measured values of the energy spent by the missile in perforating the slab differed by only 4%.

Six not so easy pieces in intermediate band solar cell research

The concept of "intermediate band solar cell" (IBSC) is, apparently, simple to grasp. However, since the idea was proposed, our understanding has improved and we feel now that we can explain better some concepts than we initially introduced. Clarifying these concepts is important, even if they are well-known for the advanced researcher, so that efforts can be driven in the right direction from start. The six pieces of this work are: Does a miniband need to be formed when the IBSC is implemented with quantum dots?; What are the problems of each of the main practical approaches that exist today? What are the simplest experimental techniques to demonstrate whether an IBSC is working as such or not? What is the issue with the absorption coefficient overlap? and Mott's transition? What the best system would be, if any?

3D Frangi-based lung vessel enhancement filter penalizing airways

This paper describes a fully automatic simultaneous lung vessel and airway enhancement filter. The approach consists of a Frangi-based multiscale vessel enhancement filtering specifically designed for lung vessel and airway detection, where arteries and veins have high contrast with respect to the lung parenchyma, and airway walls are hollow tubular structures with a non negative response using the classical Frangi's filter. The features extracted from the Hessian matrix are used to detect centerlines and approximate walls of airways, decreasing the filter response in those areas by applying a penalty function to the vesselness measure. We validate the segmentation method in 20 CT scans with different pathological states within the VESSEL12 challenge framework. Results indicate that our approach obtains good results, decreasing the number of false positives in airway walls.

Nutritive value and protein quality of soybean meals according to origin and crop year

Resultados de la investigación sobre el valor nutritivo y calidad de la proteína de la alimentación basada en soja en función del origen y del año de la recolección.

Variation among origins in nutrient composition and protein quality of soybean meals

Investigación sobre las variaciones en la composición y en la calidad de las proteinas de la alimentación animal basada en la soja en función de los orígenes

Simplified small-signal stability analysis for optimized power system architecture

The optimization of power architectures is a complex problem due to the plethora of different ways to connect various system components. This issue has been addressed by developing a methodology to design and optimize power architectures in terms of the most fundamental system features: size, cost and efficiency. The process assumes various simplifications regarding the utilized DC/DC converter models in order to prevent the simulation time to become excessive and, therefore, stability is not considered. The objective of this paper is to present a simplified method to analyze small-signal stability of a system in order to integrate it into the optimization methodology. A black-box modeling approach, applicable to commercial converters with unknown topology and components, is based on frequency response measurements enabling the system small-signal stability assessment. The applicability of passivity-based stability criterion is assessed. The stability margins are stated utilizing a concept of maximum peak criteria derived from the behavior of the impedance-based sensitivity function that provides a single number to state the robustness of the stability of a well-defined minor-loop gain.

Limits of the frequency response for the analysis of ripple-based controllers

Advanced control techniques like V2, Vout hysteresis or V2Ic can strongly reduce the required output capacitance in PowerSoC converters. Techniques to analyze power converters based on the analysis of the frequency response are not suitable for ripple-based controllers that use fast-scale dynamics to control the power stage. This paper proves that the use of discrete modeling together with Floquet theory is a very powerful tool to model the system and derive stable region diagrams for sensitivity analysis. It is applied to V 2Ic control, validating experimentally that Floquet theory predicts accurately subharmonic oscillations. This method is applied to several ripplebased controllers, providing higher accuracy when it is compared with other techniques based on the frequency response. The paper experimentally validates the usefulness of the discrete modeling and the Floquet theory on a 5 MHz Buck converter with a V 2Ic control.

Dual Active Bridge based Battery Charger for Plug-in Hybrid Electric Vehicle with Charging Current Containing Low Frequency Ripple

High power density is strongly preferable for the on-board battery charger of Plug-in Hybrid Electric Vehicle (PHEV). Wide band gap devices, such as Gallium Nitride HEMTs are being explored to push to higher switching frequency and reduce passive component size. In this case, the bulk DC link capacitor of AC-DC Power Factor Correction (PFC) stage, which is usually necessary to store ripple power of two times the line frequency in a DC current charging system, becomes a major barrier on power density. If low frequency ripple is allowed in the battery, the DC link capacitance can be significantly reduced. This paper focuses on the operation of a battery charging system, which is comprised of one Full Bridge (FB) AC-DC stage and one Dual Active Bridge (DAB) DC-DC stage, with charging current containing low frequency ripple at two times line frequency, designated as sinusoidal charging. DAB operation under sinusoidal charging is investigated. Two types of control schemes are proposed and implemented in an experimental prototype. It is proved that closed loop current control is the better. Full system test including both FB AC-DC stage and DAB DC-DC stage verified the concept of sinusoidal charging, which may lead to potentially very high power density battery charger for PHEV.

Design and Multi-Objective Optimization of EMI Input Filters

An EMI filter design procedure for power converters is proposed. Based on a given noise spectrum, information about the converter noise source impedance and design constraints, the design space of the input filter is defined. The design is based on component databases and detailed models of the filter components, including high frequency parasitics, losses, weight, volume, etc.. The design space is mapped onto a performance space in which different filter implementations are evaluated and compared. A multi-objective optimization approach is used to obtain optimal designs w.r.t. a given performance function.

Construction cost and energy consumption resulting from energy retrofitting in an apartment building in Madrid (Spain).

This theoretical study analyzes the relation between the measures necessesary for the energy retrofitting of a residential building constructed in Madrid, their cost and the improvement of the energy rating of the dwellings. The aim of this work is to establish an evaluation methodology that allows developers and architects to obtain conclusions and orientates therm in the decisioin-making process. It will allow finding the most suitable cost-effective solutions in each case. This paper describes the methodology and the findings obtained. Energy retrofitting and the improvement of the energy behaviour of the building depend on the selection of the retrofitting solutions and also on the investment. In this case study to achieve the best energy rates it is necessary to improve the thermal performance of the envelope as well as the energy systems. Energy retrofitting means an increase in property value but it can't only be considered in economic terms. It is necessary to take into account unquantifiable aspects as increased comfort, improved sound insulation, livability, health, or the elimination of energy poverty situations.