Diffractive optics at the surface of light-emitting/receiving semiconductor components

Abstract

Semiconductor components that emit or receive light can use diffractive surface structures to increase the functionality and reduce the number of additional optical components needed in the system. The diffractive structure couples the light out of, or into, the semiconductor material; it splits the light and directs it into one focus or several foci at any desired position. Further, the diffractive optics can be designed so that the function of the device is largely insensitive to the polarization of the light. In this survey, we briefly discuss design and fabrication issues, and show simulated and measured results, for a few different types of components.     

SOFT‐SLAM: Computationally efficient stereo visual simultaneous localization and mapping for autonomous unmanned aerial vehicles

Autonomous navigation of unmanned aerial vehicles (UAVs) in GPS‐denied environments is a challenging problem, especially for small‐scale UAVs characterized by a small payload and limited battery autonomy. A possible solution to the aforementioned problem is vision‐based simultaneous localization and mapping (SLAM), since cameras, due to their dimensions, low weight, availability, and large information bandwidth, circumvent all the constraints of UAVs. In this paper, we propose a stereo vision SLAM yielding very accurate localization and a dense map of the environment developed with the aim to compete in the European Robotics Challenges (EuRoC) targeting airborne inspection of industrial facilities with small‐scale UAVs. The proposed approach consists of a novel stereo odometry algorithm relying on feature tracking (SOFT), which currently ranks first among all stereo methods on the KITTI dataset. Relying on SOFT for pose estimation, we build a feature‐based pose graph SLAM solution, which we dub SOFT‐SLAM. SOFT‐SLAM has a completely separate odometry and mapping threads supporting large loop‐closing and global consistency. It also achieves a constant‐time execution rate of 20 Hz with deterministic results using only two threads of an onboard computer used in the challenge. The UAV running our SLAM algorithm obtained the highest localization score in the EuRoC Challenge 3, Stage IIa–Benchmarking, Task 2. Furthermore, we also present an exhaustive evaluation of SOFT‐SLAM on two popular public datasets, and we compare it to other state‐of‐the‐art approaches, namely ORB‐SLAM2 and LSD‐SLAM. The results show that SOFT‐SLAM obtains better localization accuracy on the majority of datasets sequences, while also having a lower runtime.     

Sacred records in the landscape: the mirila of the Dalmatian hinterland

This paper discusses former burial rites which resulted in memorials known as mirila. It deals with the custom of marking a temporary resting-place while transporting a deceased person, which was prevalent in the north-eastern Adriatic hinterland, manifested in the erection of mortarless stone structures, the remains of which can still be found in the landscape. The paper considers the material and symbolic components of the cultural landscape through the phenomenon of mirila in the central parts of the Croatian Adriatic hinterland: Ravni Kotari and Bukovica. At the same time, given the complexity of natural and socio-political factors, an attempt is made to establish how the custom arose in the spatial and historical context of the region.     

Brown rice proteins as delivery system of phenolic and volatile compounds of raspberry juice

Development of novel food ingredients with health benefits as well as desired sensory attributes is of great importance for food industry. For that purpose, complexes (BRP/R) between brown rice proteins (amounts varied; 2%, 6% and 10%) and raspberry juice were prepared. Obtained complexes were evaluated for the amount of volatile compounds, phenolic content, anthocyanin content and antioxidant activity. Those parameters depended on proteins amount. The highest adsorption of total phenolics and anthocyanins (18.18 mg g⁻¹ and 4.59 mg g⁻¹, respectively) was observed on complexes obtained with the lowest amount of proteins (2%). Regarding volatiles, dominant flavour note in raspberry juice was berry (40% of overall flavour), followed by citrus and woody notes (each around 18%), while dominant flavour note on complexes was citrus note (60%) followed by green note (15%). These results suggest an efficient plant-based approach to produce value-added protein-based complexes with possible utility as food colourant and flavouring.     

Changes in macroelements,trace elements,heavy metal concentrations and chemical composition in milk of Croatian spotted goats during different lactation stages

The research was conducted on days 60, 90, 120 and 150 during the lactation with the aim to determine the effect of lactation stage on the concentration of crucial elements and chemical composition in Croatian spotted goats' milk. Milk yield significantly decreased (from 1.15 to 0.76 kg/day), while the concentration of Ca, Mg, P, Zn and Mo in the milk of the goats significantly increased during lactation. The concentrations of Cr, Cd and Pb in milk were very low, with no significant deviations during lactation. The quality of milk from Croatian spotted goats is adequate compared with other breeds in the surrounding area of Croatia.     

Glucosinolates,glycosidically bound volatiles and antimicrobial activity of Aurinia sinuata (Brassicaceae)

Volatiles of Aurinia sinuata (L.) Griseb. were isolated from aerial parts and analysed by gas chromatography/gas chromatography–mass spectrometry (GC/GC–MS). The main compounds were glucosinolate degradation products originating from glucoberteroin, glucobrassicanapin and glucoalyssin. They were: 6-(methylthio)hexanenitrile (1.8–51.5%), 6-(methylsulfinyl)hexanenitrile (0–11.5%), 5-(methylsulfinyl)pentyl isothiocyanate (0–10.2%), 5-(methylthio)pentyl isothiocyanate (0.4–9.5%), 4-pentenyl isothiocyanate (0.7–8.9%), 5-hexenenitrile (2.6–14.6%) and 5,6-epithiohexanenitrile (0–3.4%). Also other volatiles were identified, such as fatty acids and esters (0.3–19.2%), phenols, phenylpropane derivatives and related compounds (0.4–15.8%), aliphatic alcohols and carbonyl compounds (4.2–11.6%) and some other compounds in smaller percentages.     

Aseptic Processing of Sweetpotato Purees Using a Continuous Flow Microwave System

ABSTRACT: Sweetpotato purees (SPP) were aseptically processed using a continuous flow microwave system to obtain a shelf-stable product. The dielectric properties of SPP were measured, and the dielectric constant and loss factor were within the range of the published values for fruits and vegetables. Small-scale tests were conducted in a 5-kW microwave unit to determine changes in color and viscosity with different thermal treatments. The results of these tests showed that color values (L*, a*) and viscosity did not change significantly compared with the untreated control. Pilot-scale tests were then conducted in a 60-kW microwave unit where the product was heated to 135 °C and held at that temperature for 30 s. The pilot-scale test produced a shelf-stable product with no detectable microbial count during a 90-d storage period at room temperature. This is the 1st report of aseptically packaged vegetable puree processed by a continuous flow microwave heating system.     

Retention of linalool and eugenol in hydrogels

Textural parameters of hydrogels prepared from hydrocolloids (guar gum or xanthan; 0.5 or 1% (w/w)) and disaccharides (sucrose and trehalose) were investigated after preparation and storage for 30 days. Volatile compounds (linalool or eugenol) were added to the hydrogels in order to investigate their behaviour in those systems and to determine whether there is correlation between textural parameters and their retention. Textural parameters that were evaluated were firmness, consistency, cohesiveness and index of viscosity. Regarding textural parameters, there was no significant difference between hydrogels prepared with 0.5% of hydrocolloids. With increase of the amount of added hydrocolloid, textural parameters increased and differences between sucrose- and trehalose-containing hydrogels were observed. Hydrogels prepared with trehalose had lower values of textural parameters. Correlation between texture and retention of volatile compounds was not observed or it was very low.