High Resolution Magnetic Resonance Imaging Evaluation of Cheese

ABSTRACT: The curd granules/joints structure of the Emmentaler was observed by NMR micro-imaging during the different stages of cheesemaking. During the ripening process, many carbon dioxyde microbubbles have been visualized inside the curd grains, as well as some volumes of fat outside the grains. At the end of the ripening stage, images reveal the final structure does not have a uniform lipid distribution of grains: the density is high at the boundaries and low at the center. Moisture and fat content profile of the rind has been obtained and rind-dependent water and/or fat accumulations are observed. Finally, the contrast difference between curd joints and grains of the studied samples confirms that a higher draining occurs for the joints than for the grains during cheesemaking.     

Productivity improvement through a sequencing generalised assignment in an assembly line system

This paper considers the assignment of heterogeneous workers to workstations of an assembly line in order to minimise the total production time. As the structure of the system implies that each of the workstations needs at least one worker, thus the problem can be considered as a generalised assignment problem (GAP). The objective is to perform an efficient human resource planning for a specified horizon consisting of several periods. Hence, we present an extension of the generalised assignment problem, consisting of a set of GAPs (one for each planning period) in which each GAP depends on the previous ones. A mixed integer mathematical model is presented for this sequencing assignment problem. The model is solved by an exact algorithm using Gurobi solver. It is proved that the problem is NP-hard and solving the medium and large size instances is not possible by the exact algorithms. Hence, two matheuristic approaches based on the disaggregated formulation of GAP are proposed. The first approach solves the problem through two sub-problems as the transportation formulation and assignment formulation. The second approach solves the problem by decomposition of the problem into several classical GAPs. The approaches are examined by a total of 27 instances. The results illustrate the efficiency of the proposed algorithms in the computational time and accuracy of the solutions.     

Comparative study of patch antenna loaded with slot split-ring resonators on different substrate materials

This paper presents square patch antenna loaded with slot split-ring resonators. Moreover, this paper discusses the performances of various dielectric substrates, having dielectric constants ranging from 2 to 5. Different substrate has been used to design the antenna such as Bakelite, Rogers RO 4232 and RT Duroid with dielectric constant of 4.8, 3.2 and 2.2, respectively. The resonance frequency is 2.25 GHz; these antennas are suitable for S-band and communication applications. The effect of change in substrate material on the performance of antenna is compared, in terms of reflection coefficient, bandwidth, directivity and radiation pattern.     

Design of porous silicon/PECVD SiOx antireflection coatings for silicon solar cells

The meso-porous silicon (PS) has become an interesting material owing to its potential applications in many fields, including optoelectronics and photovoltaics. PS layers were grown on the front surface of the n⁺ emitter of n⁺-p mono-crystalline Silicon junction. The thickness and the porosity of the PS layer were determined by an ellipsometer, as a function of time duration of anodization, and the variation law of the PS growth kinetics is established. Single layers PS antireflection coating (ARC) achieved around 9% of effective reflectivity in the wavelength range between 400 and 1000 nm on junction n⁺-p solar cells. To reduce the reflectivity and improve the stability and passivation properties of PS ARC, silicon oxide layers were deposited by PECVD on PS ARC. SiO_x layers of thickness of 105 nm combined with PS layer led to 3.8% effective reflectivity. V_oc measurements were carried out on all the samples by suns-V_oc method and showed an improvement of the quality of the passivation brought by the oxide layer. Using the experimental reflectivity results and taking into account the passivation quality of the samples, the PC1D simulations predict an enhancement of the photogenerated current exceeding 44%.     

Investigation of a Near-Perfect Quad-Band Polarization-Insensitive Metamaterial Absorber Based on Dual-T Circular Shaped Resonator Array Designed on a Silicon Substrate for C-, X- and Ku-bands Applications

Silicon - Multi-band metamaterial absorbers (MMAs) are increasingly becoming main devices for many electrical systems. Optimizing the electromagnetic qualities of this type of absorber in the...