Characterization of the Physical Properties of the Coconut Fiber Residue With a View to its Agroindustrial Use

Ecuador is a multi-climatic country with the capacity to host a large number of plant species; one example is the coconut (Cocos nucifera), an ancestral food of tropical areas and warm climates, which is considered as raw material for various industrial processes, such as obtaining fats, oils, candies, etc. However, the external part of the coconut constituted by the bast or mesocarp has not been properly exploited. Coconut bast, which has high fiber content (coir fiber), from which three main types can be distinguished: long and thin, coarse, and shorter type, can become an agroindustrial alternative due to its mechanical properties. These properties are as good or better than synthetic fibers or polyester. This research therefore aims to characterize the physical parameters that determine the functionality of coconut fiber, such as its length, softness, brightness, color, diameter, and its appearance or slenderness, which is the relationship between length and diameter. This research also contributes to solving the environmental problem of waste generated by coconut production, moving towards a sustainable economy from an environmental point of view. This work determines that coconut fiber is composed of cellulose and wood that has low heat conductivity and impact resistance, and that its resistance and durability make it an adequate raw material in several production sectors. Keywords: coconut fiber, characterization, properties, agribusiness. Resumen El Ecuador es un país multi climático con la capacidad de alojar una gran cantidad de especies vegetales, un ejemplo de ello es el coco (Cocos nucifera) un alimento ancestral de zonas tropicales y climas cálidos, este es considerado como materia prima de diversos procesos industriales como obtención de grasas, aceites, confites, etc., sin embargo, la parte externa del coco constituida por la estopa o mesocarpio no ha sido correctamente explotada. La estopa del coco por su alto contenido de fibra (fibra bonote), de la cual se pueden distinguir tres tipos principales: una larga y fina, una tosca y una más corta, se convertir en una alternativa agroindustrial debido a sus propiedades físico - mecánicas que son tan buenas o mejores que fibras sintéticas o el poliéster. Esta investigación tuvo por objeto caracterizar los parámetros físicos que describan la funcionalidad de la fibra de coco como son su longitud, suavidad, brillo, color. Para lo cual se realizó un estadística descriptiva de medidas de tendencia central como la media, se analizaron un total de 10 muestras de fibra de coco tomadas al azar de los 15 Kg de fibra obtenida de 50 cocos, teniéndose como resultado que para la suavidad el 80% de los participantes la ubican en el octavo lugar y el restante 20% en el noveno, lo que permite inferir que se tara de una fibra gruesa, rígida y áspera, para el brillo y luminosidad el 90% de los observadores determinaron que la fibra no posee esta característica. El 70% de las panelistas delimitaron que el color característico de la fibra fue el café claro y el restante 30% la considera de color beige. Palabras clave: fibra de coco, caracterización, propiedades, agroindustria

Thermal transpiration flow

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Thermal transpiration is the macroscopic movement of rarefied gas induced by a temperature gradient. The gas moves from the lower to the higher temperature zone. An original method is proposed here to measure the mean macroscopic movement of gas in the case of a long circular cross-section glass microtube on to which a gradient of temperature is applied. The mass flow rate and the thermo-molecular pressure difference have been measured by monitoring the absolute pressure evolution in time at both ends of the capillary using high-speed response pressure gauges. Two gases Nitrogen and Helium are studied and three different temperature differences of 50, 60 and 70 Celsius degrees are applied to the tube. The analysed gas rarefaction conditions vary from transitional to slip regime.The European Community’s Seventh Framework Program (FP7/2007-2013 under grant agreement no 215504

The challenge of modelling nitrogen management at the field scale : simulation and sensitivity analysis of N2O fluxes across nine experimental sites using DailyDayCent

Peer reviewedPublisher PD

Superfluid current disruption in a chain of weakly coupled Bose-Einstein Condensates

We report the experimental observation of the disruption of the superfluid atomic current flowing through an array of weakly linked Bose-Einstein condensates. The condensates are trapped in an optical lattice superimposed on a harmonic magnetic potential. The dynamical response of the system to a change of the magnetic potential minimum along the optical lattice axis goes from a coherent oscillation (superfluid regime) to a localization of the condensates in the harmonic trap ("classical" insulator regime). The localization occurs when the initial displacement is larger than a critical value or, equivalently, when the velocity of the wavepacket's center of mass is larger than a critical velocity dependent on the tunnelling rate between adjacent sites.Comment: 8 pages, 4 figure

High-dimensional decoy-state quantum key distribution over 0.3 km of multicore telecommunication optical fibers

Multiplexing is a strategy to augment the transmission capacity of a communication system. It consists of combining multiple signals over the same data channel and it has been very successful in classical communications. However, the use of enhanced channels has only reached limited practicality in quantum communications (QC) as it requires the complex manipulation of quantum systems of higher dimensions. Considerable effort is being made towards QC using high-dimensional quantum systems encoded into the transverse momentum of single photons but, so far, no approach has been proven to be fully compatible with the existing telecommunication infrastructure. Here, we overcome such a technological challenge and demonstrate a stable and secure high-dimensional decoy-state quantum key distribution session over a 0.3 km long multicore optical fiber. The high-dimensional quantum states are defined in terms of the multiple core modes available for the photon transmission over the fiber, and the decoy-state analysis demonstrates that our technique enables a positive secret key generation rate up to 25 km of fiber propagation. Finally, we show how our results build up towards a high-dimensional quantum network composed of free-space and fiber based linksComment: Please see the complementary work arXiv:1610.01812 (2016

Direct-detection 25 Gb/s PON: PROs and CONs of digital signal processing at the transmitter side

We evaluate the performance of direct-detection 25 Gb/s Passive Optical Networks (PON) with adaptive equalization at the receiver side, comparing three transmitter schemes: two including digital signal processing (DSP), namely square-root raised-cosine pulse shaping and pre-emphasis, and the third one without any DSP pre-compensation. We show that DSP at transmitter side can provide a performance advantage only under strong bandwidth limitations and when considering feed-forward equalization (FFE) at the receiver. When including decision-feedback equalization (DFE), the use of pre-compensation at transmitter does not provide any advantage under linear transmission

Quinstant Dark Energy Predictions for Structure Formation

We explore the predictions of a class of dark energy models, quinstant dark energy, concerning the structure formation in the Universe, both in the linear and non-linear regimes. Quinstant dark energy is considered to be formed by quintessence and a negative cosmological constant. We conclude that these models give good predictions for structure formation in the linear regime, but fail to do so in the non-linear one, for redshifts larger than one.Comment: 9 pages, 14 figures, "Accepted for publication in Astrophysics & Space Science

First steps of a nucleation theory in disordered systems

We devise a field theoretical formalism for a microscopic theory of nucleation processes and phase coexistence in finite dimensional glassy systems. We study disordered $p$-spin models with large but finite range of interaction. We work in the framework of glassy effective potential theory which in mean-field is a non-convex, two minima function of the overlap. We will associate metastability and phase coexistence with the existence of space inhomogeneous solution of suitable field equations and we will study the simplest of such solutions.Comment: 31 pages, 4 figures. Content revised, typos correcte