51 research outputs found
Modelos de oscilaciones caóticas en superredes semiconductoras a temperatura ambiente
No full textEsta tesis doctoral está centrada en el estudio de superredes semiconductoras
débilmente acopladas. Una de las bondades de esta clase de dispositivos es la
posibilidad de ser una fuente de números aleatorios puros con una tasa muy alta de
generación. Al ser dispositivos cuyo funcionamiento es totalmente electrónico y que
pueden ser fácilmente integrados en un circuito, ésto las convierte en contendientes
muy interesantes para usos donde haga falta tales generadores, como lo son el
almacenamiento y transmisión segura de información, juegos de azar electrónicos,
y simulaciones estocásticas.
Una cuestión pertinente es si se puede garantizar la presencia de caos a la hora
de ser fabricadas, pues es el mecanismo por el cual son buenas generadoras de
números aleatorios. Abordaremos, de manera teórica, el problema de diseñar una
superred que presente comportamiento caótico demanera natural y admita cierto
margen de error a la hora de ser fabricada. En el camino recogeremos ciertos
criterios a seguir en caso de querer reproducir los pasos teóricos, sin necesidad
de disponer de toda la información que nos brinda el modelo y, simplemente,
bastándose de observaciones macroscópicas.
Otra aplicación de las superredes es que, por su comportamiento no lineal,
pueden interactuar con fuentes de ruido y sincronizarse con señales ocultas en
éste, como incluso amplificarlas. Es decir, pueden ser utilizadas para la detección
de señales suficientemente débiles como para no distinguirse del ruido de fondo,
sin necesidad de disponer de conocimiento previo de la frecuencia de esas señales.
Este tema también será abordado en este trabajo y, además, será contrastado experimentalmente.También he de agradecer al Ministerio de Economía y Competitividad de España
por la financiación brindada a través de los proyectos MTM2014-56948-C2-2-P y
MTM2017-84446-C2-2-R. Además, agradecer de nuevo al mismo por el programa
de Formación de Doctores, cofinanciado por el Fondo Social Europeo.Programa de Doctorado en Ingeniería Matemática por la Universidad Carlos III de MadridPresidente: Antonio Marquina Vila.- Secretario: Eduardo Jesús Sánchez Villaseñor.- Vocal: Ana María Carpio Rodrígue
HUBUNGAN FAKTOR-FAKTOR YANG MEMPENGARUHI KAPASITAS KERJA TERHADAP KELELAHAN TENAGA KERJA DI BAGIAN PALET PT AGUNG SAPUTRA-TEX YOGYAKARTA
No full textKapasitas kerja adalah kemampuan seseorang pekerja untuk menyelesaikan pekerjaannya dalam suatu medan kerja tertentu. Kemampuan kerja seorang tenaga kerja berbeda dan sangat tergantung pada ketrampilan, keserasian, status gizi, status kesehatan, jenis kelamin, usia dan ukuran-ukuran tubuh. Salah satu akibat yang dapat dirasakan oleh tenaga kerja adalah terjadinya kelelahan.
Tujuan penelitian adalah untuk mengetahui hubungan faktor-faktor kapasitas kerja dengan kelelahan tenaga kerja di bagian kPalet PT Agng Saputra-Tex Yogyakarta. Jenis penelitian adalah Explanatory dengan pendekatan cross sectional. Sampel yang diambil adalah seluruh jumlah populasi tenaga kerja yang berada di bagian Palet. Untuk mengetahui kelelahan diukur dengan memakai indikator kecepatan waktu reaksi cahaya dengan alat reaction timer. Analisa dat dengan uji korelasi pearson menggunakan SPSS 10.0.
faktor umur dan status gizi berhubungan secara signifikan dengan kelelahan. Besar hubungan antara umur dengan kelelahan adalah 0,622 (r=0,622), antara masa kerja dengan kelelahan adalah 0,570 (r=0,570) dan antara status gizi dengan kelelahan adalah -0,478 (r=-0,478).
Saran yang diberikan sehubungan dengan hasil penelitian adalah agar pihak perusahaan memperhatikan karakteristik pekerja seperti umur dalam penerimaan tenaga kerja sehingga sesuai dengan spesialisasi pekerjaan, pengaturan gizi yang lebih baik bagi tenaga kerja agar status gizi tenaga kerja semakin baik.
Kata Kunci: KELELAHAN, TENAGA KERJ
Emerging regional innovation policies for industry 4.0: analyzing the digital innovation hub program in European regions
No full textThis article is (c) Emerald Group Publishing and permission has been granted for this version to appear here (please insert the web address here). Emerald does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Emerald Group Publishing Limited.[EN] Purpose Industry 4.0 or digitization, from a regional innovation system (RIS) and policy perspective to improve regional innovation, is over-looked. Specifically, this paper aims to focus on analyzing the nascent European Commission (EC) digital innovation hub (DIH) program, designed for fostering transition into Industry 4.0 in regions and facilitating new path development. Design/methodology/approach Empirically, 10 Spanish DIH is explored through interviews and secondary data analysis. Findings The results suggest that DIHs despite their emerging and trial-and-error stage are designed for promoting multi-actor collaborative platforms including non-local actors to stimulate transition into Industry 4.0 by promoting place-based collaboration alliances that respond to local/regional contextual specificities and demands. These regional-based platforms facilitate public-private partnerships that co-design policy initiatives resulting from co-participation and negotiation of spatially-bounded oriented initiatives for digitizing. Originality/value The authors answer: what are the key characteristics of emerging European-level regional innovation policies aimed at facilitating Industry 4.0 in regions? This is the first study on the topic.Ministerio de Ciencia, Innovacion y Universidades: RTI2018-095739-B-100.Hervás Oliver, JL.; González-Alcaide, G.; Rojas-Alvarado, R.; Monto-Mompo, S. (2021). Emerging regional innovation policies for industry 4.0: analyzing the digital innovation hub program in European regions. Competitiveness Review. 31(1):106-129. https://doi.org/10.1108/CR-12-2019-0159S10612931
Impact of alkaline thermal hydrolysis on anaerobic digestion of mixed sludge contaminated with microplastics
No full text[EN] The widespread presence of microplastics in wastewater treatment plants is well-documented and their detrimental impact on different unit processes has been established by the scientific community. This study aims to advance the understanding of how a still little-known process, alkaline thermal hydrolysis process (ATHP) of the mixed sludge (pH = 10, temperature = 125 degrees C, exposure time = 60 min), affects the subsequent anaerobic digestion in presence of two commonly found microplastics (polyethylene and polyvinylchloride) in the sludge. Biochemical methane potential test (BMP) was performed with sludge samples without and with ATHP and with and without microplastics (MPs) doping for 35 days. Results indicated a partial degradation of the MPs during ATHP according to the Raman spectra. Concerning cumulative methane production, the maximum production was obtained for the samples with microplastics, irrespective of the pretreatment. However, it was observed that ATHP alleviated the decrease in methane production in the digesters. In fact, for the highest polyethylene concentration, the digester with pretreated sludge yielded a 111 % higher methane production that the digester without pretreatment. It can be concluded that ATHP reduces the inhibition of the anaerobic process in presence of MPs. Environmental implication: This study addresses the environmental risk posed by microplastics (PE and PVC) in wastewater sludge by evaluating their behaviour during alkaline thermal hydrolysis and subsequent anaerobic digestion. Results show partial degradation of the polymers and a reduction in their inhibitory effects on methane production. These findings highlight a viable strategy to mitigate the environmental impact of persistent contaminants in sludge treatment systems. The proposed approach contributes to improved energy recovery and safer biosolids management, offering a practical solution for wastewater treatment plants facing increasing microplastic contamination.Raul Mompo Curell expresses his gratitude to the Spanish Ministry of Science, Innovation and Universities for having funded his research stay during his PhD (grant EST24/00574) in Civil and Environmental Engineering Department (University of Alberta, Canada) . The authors acknowledge the financial support from the Spanish Ministry of Science and Innovation (Reference of the project: PID2021-127468OB-I00) . Additionally, the grant FPU20/07709 was funded by the Spanish Ministry of Education and Vocational Training. The research at the University of Alberta was supported by Dr. B. R. Dhar's Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) . Graphical abstract was created in BioRender. Mompo Curell, R. (2024) BioRender.com /z08a384.Mompó-Curell, Raúl;Mostafa, A.;Mendoza Roca, José Antonio;Bes-Piá, M.A.;Dhar, BR. (2025). Impact of alkaline thermal hydrolysis on anaerobic digestion of mixed sludge contaminated with microplastics. Journal of Water Process Engineering. 80. https://doi.org/10.1016/j.jwpe.2025.109160S8
Determination of benzomercaptans in environmental complex samples by combining zeolitic imidazolate framework-8-based solid-phase extraction and high-performance liquid chromatography with UV detection
No full text[EN] In this work, the synthesis of zeolitic imidazolate framework-8 (ZIF-8) crystals and their subsequent application as effective sorbents for extraction and preconcentration of several benzomercaptans from environmental complex samples is described. These materials were prepared by solvothermal approach varying the concentration of n-butylamine modulator to modify the surface of the metal-organic framework. The resulting materials were characterized by scanning and transmission electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. The ZIF-8 material that gave the best features was selected as extractive phase and the influence of various parameters (sample pH and elution solvent composition, among others) on the extraction efficiency of target compounds were investigated. Under the optimal conditions of the method, the tested analytes (2-mercaptobenzothiazole, 2-mercaptobenzoxazole and 2-mercapto-6-nitrobenzothiazole) were retained and eluted quantitatively with alkaline 50:50 (v:v) methanol-water mixture. Using the proposed method, low limits of detection, in the range of 16-21 ng L-1 for aqueous samples and 0.4-0.5 mu g kg(-1) for soil samples, were achieved whereas the precision (expressed as relative standard deviation) was lower than 7%. The resulting solid-phase extraction protocol, using the zeolitic material as sorbent, was combined with liquid chromatography and ultraviolet-vis detector and successfully applied to determine traces of these organic pollutants in environmental samples. (C) 2020 Elsevier B.V. All rights reserved.The authors would like to gratefully acknowledge the financial support received from the project RTI2018-095536-B-I00 (Ministry of Science, Innovation and Universities, Spain). Spanish Agencia Estatal de Investigacion (AEI-Spain) and the European Funds for Regional Development (FEDER-European Union) are also gratefully acknowledged for financial support through Project CTQ2016-77155-R (AEI/FEDER, UE).). H. M. P-C. and N.C. thank the support from the Spanish Ministry of Science, Innovation and Universities (MCIU) for FPU pre-doctoral fellowships. The authors extend their appreciation to MCIU for granting the Spanish Network of Excellence in Sample preparation (RED2018-102522-T). This article is based upon work from the Sample Preparation Task Force and Network, supported by the Division of Analytical Chemistry of the European Chemical Society.Martinez-Perez-Cejuela, H.; Mompo-Rosello, O.; Crespi-Sanchez, N.; Palomino Cabello, C.; Catalá-Icardo, M.; Simo-Alfonso, EF.; Herrero-Martinez, JM. (2020). Determination of benzomercaptans in environmental complex samples by combining zeolitic imidazolate framework-8-based solid-phase extraction and high-performance liquid chromatography with UV detection. Journal of Chromatography A. 1631:1-9. https://doi.org/10.1016/j.chroma.2020.461580S19163
Designing Hyperchaos and Intermittency in Semiconductor Superlattices
No full textWeakly coupled semiconductor superlattices under dc voltage bias are excitable systems with many degrees of freedom that may exhibit spontaneous chaos at room temperature and act as fast physical random number generator devices. Superlattices with identical periods exhibit current self-oscillations due to the dynamics of charge dipole waves but chaotic oscillations exist on narrow voltage intervals. They disappear easily due to variation in structural growth parameters. Based on numerical simulations, we predict that inserting two identical sufficiently separated wider wells increases superlattice excitability by allowing wave nucleation at the modified wells and more complex dynamics. This system exhibits hyperchaos and varieties of intermittent chaos in extended dc voltage ranges. Unlike in ideal superlattices, our chaotic attractors are robust and resilient against noises and against controlled random disorder due to growth fluctuations.We acknowledge support by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación Grants No. MTM2017-84446-C2-2-R and No. PID2020-112796RB-C22, by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M23), and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation)
Link-level effect of a noisy channel over data transmission on the return path of an HFC network
No full textMemory effects in a gas of viscoelastic particles
No full textWe study a granular gas of viscoelastic particles (kinetic energy loss upon collision is a function of the particles' relative velocities at impact) subject to a stochastic thermostat. We show that the system displays anomalous cooling and heating rates during thermal relaxation processes, this causing the emergence of thermal memory. In particular, a significant Mpemba effect is present, i.e., an initially hotter/cooler granular gas can cool down/heat up faster than an in comparison cooler/hotter granular gas. Moreover, a Kovacs effect is also observed, i.e., a nonmonotonic relaxation of the granular temperature¿if the gas undergoes certain sudden temperature changes before fixing its value. Our results show that both memory effects have distinct features, very different and eventually opposed to those reported in theory for granular fluids under simpler collisional models. We study our system via three independent methods: approximate solution of the kinetic equation time evolution and computer simulations (both molecular dynamics simulations and direct simulation Monte Carlo method), finding good agreement between them.This work has been partially funded by the Spanish Ministerio de Ciencia, Innovación y Universidades and the Agencia Estatal de Investigación through Grant Nos. MTM2017-84446-C2–2-R (A.L., E.M., and A.T.), FIS2017-84440-C2–2-P (A.T.), and FIS2016-76359-P. (F.V.R.). M.A.L.C. and F.V.R. also acknowledge support from the regional Extremadura Government through Project Nos. GR18079 and IB16087. Computing facilities from the Extremadura Research Centre for Advanced Technologies (CETA-CIEMAT) are also acknowledged. All grants and facilities were provided with partial support from the ERDF
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