Operational Solution to the Nonlinear Klein-Gordon Equation

Supported by Grant SEP-CONACYT 220603, the first author was supported by SEP-PRODEP through the project UAM-PTC-630, the third author was supported by Portuguese National Funds through the FCT Foundation for Science and Technology under the project PEst-UID/EEA/00066/2013We obtain solutions of the nonlinear Klein-Gordon equation using a novel operational method combined with the Adomian polynomial expansion of nonlinear functions. Our operational method does not use any integral transforms nor integration processes. We illustrate the application of our method by solving several examples and present numerical results that show the accuracy of the truncated series approximations to the solutions.authorsversionpublishe

Assessment of the adequacy of different Mediterranean waste biomass types for fermentative hydrogen production and the particular advantage of carob (Ceratonia siliqua L.) pulp

ABSTRACT: The conversion of agro-industrial byproducts, residues and microalgae, which are representative or adapted to the Mediterranean climate, to hydrogen (H2) by C. butyricum was compared. Five biomass types were selected: brewery’s spent grain (BSG), corn cobs (CC), carob pulp (CP), Spirogyra sp. (SP) and wheat straw (WS). The biomasses were delignified and/or saccharified, except for CP which was simply submitted to aqueous extraction, to obtain fermentable solutions with 56.2e168.4 g total sugars L 1. In small-scale comparative assays, the H2 production from SP, WS, CC, BSG and CP reached 37.3, 82.6, 126.5, 175.7 and 215.8 mL (g biomass) 1, respectively. The best fermentable substrate (CP) was tested in a pH-controlled batch fermentation. The H2 production rate was 204 mL (L h) 1 and a cumulative value of 3.9 L H2 L 1 was achieved, corresponding to a H2 production yield of 70.0 mL (g biomass) 1 or 1.6 mol (mol of glucose equivalents) 1. The experimental data were used to foresight a potential energy generation of 2.4 GWh per year in Portugal, from the use of CP as substrate for H2 production.info:eu-repo/semantics/publishedVersio

How Many Fractional Derivatives Are There?

Funding: This work was partially funded by National Funds through the FCT-Foundation for Science and Technology within the scope of the CTS Research Unit—Center of Technology and Systems/UNINOVA/FC /NOVA, under the reference UIDB/00066/2020, and also by FCT through IDMEC, under LAETA, project UID/EMS/50022/2020. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.In this paper, we introduce a unified fractional derivative, defined by two parameters (order and asymmetry). From this, all the interesting derivatives can be obtained. We study the one-sided derivatives and show that most known derivatives are particular cases. We consider also some myths of Fractional Calculus and false fractional derivatives. The results are expected to contribute to limit the appearance of derivatives that differ from existing ones just because they are defined on distinct domains, and to prevent the ambiguous use of the concept of fractional derivative.publishersversionpublishe

On the Numerical Computation of the Mittag-Leffler Function

The Mittag-Leffler function (MLF) plays an important role in many applications of fractional calculus, establishing a connection between exponential and power law behaviors that characterize integer and fractional order phenomena, respectively. Nevertheless, the numerical computation of the MLF poses problems both of accuracy and convergence. In this paper, we study the calculation of the 2-parameter MLF by using polynomial computation and integral formulas. For the particular cases having Laplace transform (LT) the method relies on the inversion of the LT using the fast Fourier transform. Experiments with two other available methods compare also the computational time and accuracy. The 3-parameter MLF and its calculation are also considered.publishe

Efficient digital self-calibration of video-rate pipeline ADCs using white gaussian noise

Proceedings of IEEE, ISCAS 2003, Vol.I, pp. 877-880A digital-domain self-calibration technique for video-rate pipeline A/D converters based on a white Gaussian noise input signal is presented. The implementation of the proposed algorithm requires simple digital circuitv. An application design example of the self-calibration of a IZb. 40 MUS CMOSpipeline ADC is shown to illustrate that the overall linearity of the ADC can be highly improved using this technique

Painful Thyroid Palpation

A 37-years-old woman, complaining of fever, malaise, myalgia, sore throat and dysphagia lasting for 15 days, had been taking antibiotics and paracetamol for 7 days, without symptoms' improvement. The clinical examination revealed hyperaemic oropharynx and enlarged, painful thyroid. Further exams showed increased analytic inflammatory serum parameters as well as thyrotoxicosis. The thyroid gland had heterogeneous echostructure, with markedly hypoechoic areas and significant capsular oedema as well as decreased radionuclide uptake in the scintigraphy. Both symptoms and imaging improved with paracetamol and ibuprofen. Thyroid gland function normalized in two months. The patient remains in follow-up. This case reports the clinical features of subacute or De Quervain's thyroiditis. The differential medical approach to the patient with painful thyroid palpation is discussed. The diagnosis is essentially clinic, highlighting the importance of a rigorous physical exam. These patients' follow-up is required, considering the clinical and analytic progression

Energy requirements for the continuous biohydrogen production from Spirogyra biomass in a sequential batch reactor

The current energy market requires urgent revision for the introduction of renewable, less-polluting and inexpensive energy sources. Biohydrogen (bioH2) is considered to be one of the most appropriate options for this model shift, being easily produced through the anaerobic fermentation of carbohydrate-containing biomass. Ideally, the feedstock should be low-cost, widely available and convertible into a product of interest. Microalgae are considered to possess the referred properties, being also highly valued for their capability to assimilate CO2 [1]. The microalga Spirogyra sp. is able to accumulate high concentrations of intracellular starch, a preferential carbon source for some bioH2 producing bacteria such as Clostridium butyricum [2]. In the present work, Spirogyra biomass was submitted to acid hydrolysis to degrade polymeric components and increase the biomass fermentability. Initial tests of bioH2 production in 120 mL reactors with C. butyricum yielded a maximum volumetric productivity of 141 mL H2/L.h and a H2 production yield of 3.78 mol H2/mol consumed sugars. Subsequently, a sequential batch reactor (SBR) was used for the continuous H2 production from Spirogyra hydrolysate. After 3 consecutive batches, the fermentation achieved a maximum volumetric productivity of 324 mL H2/L.h, higher than most results obtained in similar production systems [3] and a potential H2 production yield of 10.4 L H2/L hydrolysate per day. The H2 yield achieved in the SBR was 2.59 mol H2/mol, a value that is comparable to those attained with several thermophilic microorganisms [3], [4]. In the present work, a detailed energy consumption of the microalgae value-chain is presented and compared with previous results from the literature. The specific energy requirements were determined and the functional unit considered was gH2 and MJH2. It was possible to identify the process stages responsible for the highest energy consumption during bioH2 production from Spirogyra biomass for further optimisation

Microalgae biomass as fermentation substrate for hydrogen and butyric acid production by clostridium tyrobutyricum

Fossil fuels are a limited type of feedstock, increasingly expensive, and carrying strong polluting properties. The search for alternative sources which can replace fossil fuels without the severe disadvantages that its use conveys is therefore of paramount importance. Microalgae biomass represents an example of such non-food renewable biomass that can be regarded as a valid alternative to fossil fuels. As biomass, microalgae are highly desirable since they are photosynthetic organisms with a very fast growth rate in comparison to higher plants, and their production does not require arable land or potable water. Furthermore, some microalgae are able to store large amounts of oil or sugars, prime materials for the production of biofuels and bulk-chemicals [1]. Scenedesmus obliquus is a microalgae with the referred properties, easily produced at large scale and capable of storing a high amount of sugars under nitrogen shortage. The objective of the present work was to investigate the production of hydrogen and butyrate from S. obliquus hidrolysate by four hydrogen- and butyrate-producing bacterial strains previously isolated by us and identified as Clostridium tyrobutyricum 1T, 2T, 3T and 9P. S. obliquus biomass was produced locally in air-lifts. After harvest, all biomass was submitted to acid pre-treatment [2] resulting in a microalgae hydrolysate with a final concentration of 10.3 g/l of glucose, xylose, arabinose, mannose and galactose. The hydrolysate was used as carbon and energy source for hydrogen and butyrate production by the four C. tyrobutyricum isolates. Hydrogen yields ranged from 0.63, 1.29, 1.36 and 1.24 of mol H2/ mol sugars by strains 1T, 2T, 3T and 9P, respectively. Hydrogen production was accompanied by the production of carbon dioxide and organic acids, mainly butyrate. Butyrate yields were 0.29, 0.49 and 0.48 mol butyric acid/ mol sugars, respectively by C. tyrobutyricum strains 1T, 2T and 3T, and 9P. The best C. tyrobutyricum isolate for combined hydrogen and butyrate production from S. obliquus hydrolysate will be used in further studies of energetic valorisation of spent algal biomass available from both biodiesel and bioethanol processes

Energetic and environmental evaluation of microalgae biomass fermentation for biohydrogen production

This paper presents an energetic and environmental evaluation of the fermentative hydrogen production from the sugars of Scenedesmus obliquus biomass hydrolysate by Clostridium butyricum. The main purpose of this work was to evaluate the potential of H2 production and respective energy consumptions and CO2 emissions in the global fermentation process: hydrolysis of S. obliquus biomass, preparation of the fermentation medium, degasification and incubation. The scale-up to industrial production was not envisaged. Energy consumption and CO2 emissions estimations were based on SimaPro 7.1 software for the preparation of the fermentation medium and the use of degasification gas, nitrogen. The functional unit of energy consumption and CO2 emissions was defined as MJ and grams per 1 MJ of H2 produced, respectively. The electricity consumed in all hydrogen processes was assumed to be generated from the Portuguese electricity production mix. The hydrogen yield obtained in this work was 2.9 ± 0.3 mol H2/mol sugars in S. obliquus hydrolysate. Results show that this process of biological production of hydrogen consumed 281-405 MJ/MJH2 of energy and emitted 24-29 kgCO2/ MJH2. The fermentation stages with the highest values of energy consumption and CO2 emissions were identified for future energetic and environmental process optimisation