Miracle-dz/UniFAR-FTUs huggingface dataset:
Model reduction for the forming process of fibrous composites structures via second gradient enriched continuum models

Abstract This paper describes phenomena associated to the microstructure, such as the local bending stiffness of the yarns, with a second gradient parameter associated to terms in the energy with higher order derivatives. The results obtained with this enriched continuous model are presented and it is shown how the main deformation mode can be controlled to reproduce experimental evidence. In particular, increasing the second gradient parameter, the deformation mode switches from shear to one with a constant curvature along the specimen. Two fibrous composite reinforcements with two different geometries are modeled: composite airframe for aeronautic industry and an automotive leaf-spring for automotive industry. The two application cases are described as homogeneous second gradient continua with an energy depending on the in-plane and out-of-plane curvature of the yarns. This addition allows to take into account the effects of the local bending stiffness of the yarns at the mesoscale in a homogenized way.
Influence of kneading ratio on the binding interaction of coke aggregates on manufacturing a carbon block

Coke aggregates and carbon artifacts were produced to investigate the interactions of coke and pitch during the kneading process. In addition, the kneading ratio of the coke and binder pitch for the coke aggregates was controlled to identify the formation of voids and pores during carbonization at 900°C. Experiments and thermogravimetric analysis revealed that carbon yields were improved over the theoretical yield calculated by the weight loss of the coke and binder pitch; the improvement was due to the binding interactions between the coke particles and binder pitch by the kneading process. The true, apparent, and bulk densities fluctuated according to the kneading ratio. This study confirmed that an excessive or insufficient kneading ratio decreases the density with degradation of the packing characteristics. The porosity analysis indicated that formation of voids and pores by the binder pitch increased the porosity after carbonization. Image analysis confirmed that the kneading ratio affected the formation of the coke domains and the voids and pores, which revealed the relations among the carbon yields, density, and porosity.
Extração e explicitação de relações semânticas para a representação do conhecimento de documentos acadêmicos: um estudo de caso a partir de uma estrutura classificatória

As relacoes semânticas sao fundamentais para a compreensao da natureza da ligacao entre dois conceitos em um dominio. Para documentos academicos, como dissertacoes e teses, a representacao do conhecimento inerente a eles, com relacoes semânticas explicitadas, apoiam a compreensao dos usuarios sobre pesquisas, por vezes complexas, de determinado dominio. Assim, o objetivo desta tese e propor um modelo de extracao de relacoes semânticas para a representacao do conhecimento de documentos academicos no contexto do idioma portugues brasileiro. Para a elaboracao do modelo, foi realizado um levantamento bibliografico com os assuntos que permeiam a tematica da tese. Desse modo, um dos resultados foi uma compilacao de classificacoes de relacoes semânticas de varios autores em uma taxonomia de relacoes semânticas em portugues. Foi realizada ainda uma revisao de literatura que apontou a carencia de pesquisas sobre extracao de relacoes semânticas no cenario nacional. Nesse contexto, um sistema de informacao na web chamado Semantizar foi desenvolvido para dar suporte a extracao de relacoes semânticas a partir de estruturas classificatorias que representam documentos academicos especificos. Desse modo, o Semantizar realiza buscas, nesses documentos, de pares de conceitos em frases, indicando a existencia de relacao semântica. Um estudo de caso foi realizado para avaliar a extracao e a explicitacao de relacoes semânticas por meio do Semantizar, nesse sentido, o sistema trouxe contribuicoes importantes para as pesquisas sobre extracao de relacoes semânticas. Os resultados demonstram que quando dois conceitos de uma estrutura classificatoria existem em uma frase, uma relacao semântica entre eles pode existir de fato. Outra contribuicao importante foi a descoberta de um novo subtipo de relacao semântica associativa, que recebeu o nome de agente-subordinado. Por fim, conclui-se que esta pesquisa e relevante para comunidade cientifica, sobretudo porque ela traz constatacoes importantes para a extracao de relacoes semânticas para a representacao do conhecimento de documentos academicos para serem aplicadas no cenario brasileiro.
An Anti-shoulder-surfing Authentication Scheme of Mobile Device

Text-based passwords, such as personal identification number (PIN) and Android screen pattern locks, are the most commonly used identity authentication method in smartphones. However, text-based passwords are unable to prevent shoulder-surfing attacks; by directly looking at the passwords entered by users, attackers are able to steal the users’ passwords, which poses significant threats to the users. In this study, a new authentication mechanism was introduced. Such a method enabled users to send out misleading information to attackers when the former entered its text-based passwords; the latter was unable to decipher the true passwords by simply recording or looking at them. The misleading information was the pressure values (i.e., pressures exerted by the users) measured by pressure sensors embedded under the smartphone touchscreens. The systems detected each pressure value entered by the users and determined whether it was to be saved (i.e., as a true password) or omitted (i.e., as misleading information). Regarding this authentication method, because attackers were unable to know the users’ pressure values, they were unable to differentiate between true and misleading information and thus had no way of knowing the users’ actual passwords. In the end, our authentication mechanism improved the deficiency of current text-based passwords and enhanced system security.
The Imbibition Process of Terylene and Polypropylene Fabrics

Capillary imbibitions were of practical importance in many industrial processes such as textile, ceramic, and pharmaceutical industries. In earlier studies, it had been found that the resistivity of terylene or polypropylene fabrics decreased via water penetration, but little work has been done on imbibitions process which is essential to reveal the interrelation between water penetration and conductivity of terylene or polypropylene fabrics. The study was inspired by the requirement to investigate more details about these interrelations. The results showed that drop spreading existed in imbibitions experiments when the hydrophobic fabrics were contacted with water. Five different physical stages occurred successively during the imbibitions behavior experiments, namely solid-liquid contact(A), imbibition(B), steady balance(C), solid-liquid separation(D) and evaporation of external liquids(E) stages. The phase of solid-liquid contact reflects the equilibrium relationship between the wetting tension and the buoyancy of the liquid. The resistivity of polypropylene fibrous decreased to 2.4×105Ω•cm when WHC was 0.01Lm-2, thus would be enough to meet a demand or requirement for collectors. The discharge current by polypropylene collection electrode was 5~20 percent higher than that by FRP. The spontaneous immersion for water into hydrophobic fabric collectors would be of practical importance for the purpose of uniform water film distribution via capillary flow, thus would allow lower water addition rate and non-interrupted operation for industrial use.
Modeling performance of response surface methodology and artificial neural network

In recent years, response surface methodology (RSM) which is a statistical technique and artificial neural network (ANN) a soft computing technique have been highly used for modelling, simulation and optimization of several physical processes in engineering. Both RSM and ANN strategies have particular computational properties that makes them suitable for making predictions, but differ in their extrapolation and interpolation capabilities on complex non-linear processes, and thus potentially conflict in their predictive accuracy. This study models and compares the capabilities of RSM and ANN in predicting the tensile strength of a 6 mm thick mild steel gas tungsten arc welded plate based on the effects of input variables such as weld current, weld speed, gas flow rate and filler rod. The RSM and ANN based models for prediction were compared using the coefficient of determination criteria. With a higher value of 0.836, the ANN model proved to be a better modeling technique than the RSM model. Keywords: Soft Computing Techniques, Response Surface Method, Artificial Neural Network
Applying Vstress and defect activation coverage to produce zero-defect mixed-signal automotive ICs

The test and design methodology currently used to develop automotive mixed-signal integrated circuits, is not sufficient to achieve the < 10 PPB quality target. In particular it does not allow to activate and detect all latent defects, which are a significant cause of vehicle failures in the field. This paper discusses whether full burn-in will be needed in order to meet the quality goal, or whether Vstress in combination with a defect activation coverage methodology will do the job.
Properties and Filtration Performance of Porous Clay Membrane Produced Using Sawdust as Pore Forming Agent

This study investigated the effect of sawdust at 0, 10, 20, 30 and 40 wt% towards physical properties and filtration efficiency of porous clay membrane. Sawdust in various quantities was added into water containing clay, polyethylene glycol and sodium silicate and then stirred to form homogenized slurry. The slurry then was casted into Plaster of Paris (PoP) mould. The green body was cut into required sizes, dried and sintered in furnace at 1000 °C. The porosity and density of porous clay was determined by Archimedes principle, while morphology was observed by Hitachi Tabletop Scanning Electron Microscope (TTSEM). The filtration test was examined on a dead-end filtration setup in batch mode operation using nitrogen as carrier gas. Distilled water was filtered and used to determine membrane permeability, while aquaculture wastewater filtration was used to determine the turbidity removal. Turbidity of aquaculture wastewater and effluent (after filtration) were measured using turbidity meter. The results indicated that porosity increased from 38 % to 64 %, while density decreased from 1.5 g/cm3 to 0.8 g/cm3 with increasing amount of sawdust from 0 to 40 wt%. This data was supported by TTSEM which is indicate that the amount of pores increased with increasing amount of sawdust. Permeation of membrane increased from 45289 to 143999 L.h-1.m-2.bar-1 and efficiency of turbidity removal increased from 87 % to 89 % with increasing amount of sawdust from 0 to 40 wt%. As conclusion, 30 wt% was an optimum amount of sawdust which is produced ceramic membrane with good structure integrity, porosity, high permeability and high turbidity removal.
Topology optimization for heat flow manipulation

The aim of this thesis is to explore the use of topology optimization in designing materials for heat flow manipulation. Specifically shielding, concentrating or even inverting the heat current was examined. The possibility to scale the problem from macro- to nano-dimensions by using topology optimization for nanoscale heat conduction was also investigated. An optimization tool for heat flux shielding, focusing and reversal is presented. Different objective functions were defined in order to shield, focus or reverse heat flow within an area surrounded by a composite material with anisotropic thermal conductivity. The composite material under consideration consisted of thermally conductive elliptical inclusions embedded in a poor conductive matrix. The effective thermal conductivity was defined based on the equivalent inclusion theory. The dependence of the anisotropic thermal conductivity on the angle that the inclusions make with the imposed gradient was then approximated via a coordinate transformation. The material distribution method for topology optimization was then used to find the optimum angle distribution of the inclusion angle for heat shielding, focusing and reversal. The use of topology optimization for heat conduction in nanostructures was also investigated. At such small length scales the classical Fourier model for heat conduction is no longer applicable. As the dimensions of a structure become comparable to the mean free path of heat carriers (electrons or phonons), heat transfer changes from diffusive to semi-ballistic. Length scale effects such as scattering of the heat carriers with other phonons, material interfaces and boundaries become important. To take into account all this length effects, a more accurate model is given by the kinetic theory. Specifically the Boltzmann Transport Equation (BTE) for phonon transport was used to model the transfer of heat. To solve the BTE, a deterministic discrete ordinates method (DOM) was used in combination with the finite element method. Using COMSOL Multiphysics, the Boltzmann transport equation was successfully coupled with the MMA optimization algorithm and a Helmholtz PDE based filter. The method was implemented for the optimization of a simple system in order to illustrate its applicability.
Alignment of energy levels in amorphous oxides and at semiconductor-water interfaces

Amorphous oxides are currently key materials in many technological applications, e.g. as gate dielectrics in metal-oxide-semiconductor (MOS) devices, and as coating layers to protect water-splitting photoanodes from corrosion. It is experimentally demonstrated that a sizeable amount of impurities (e.g. carbon, nitrogen and hydrogen) are inevitably incorporated into these amorphous films either intentionally or unintentionally, due to doping or to the growth process. Defects, including both extrinsic and intrinsic, may induce some defect levels and impact the performance of these oxides in special applications. To understand their underlying role, we conduct a detailed investigation of defects in two representative amorphous oxides: amorphous Al2O3 (am-Al2O3) and TiO2 (am-TiO2), by combining ab i ni t i o molecular dynamics (MD) simulations and hybrid functional calculations. Our results indicate that oxygen vacancies and interstitials occur neither in am-Al2O3 nor in am-TiO2 due to structural rearrangements which assimilate the defect structure, and that the injection of extra holes can lead to the formation of O-O peroxy linkages. In am-Al2O3, hydrogen is found to be amphoteric. Based on localized Wannier functions, we identify the nominal charge state and the composition of the defect core unitis related to C and N impurities in am-Al2O3, which are found to depend on the total charge set in the simulation cell. Through the adopted electron counting rule, we assess that carbon and nitrogen impurities are only found in neutral and in singly positive charge states, respectively, indicating that none of them gives charge transition levels in am-Al2O3. In addition, those defect core units are shown to incorporate a varying number of oxygen atoms, by which their formation energy is dependent on the oxygen chemical potential. After excluding the role of oxygen vacancies in hole diffusion processes in am-TiO2, we focus on the formation of O-O pairs to accommodate extra holes and propose an exchange mechanism for hole transport in am-TiO2 that relies on the simultaneous breaking and forming of O-O peroxy linkages that share one O atom. Through the use of nudged-elastic-band calculations, a hopping path as long as 1.2 nm with barriers of 0.3-0.5 eV is demonstrated, suggesting that hole diffusion through O-O peroxy linkages is viable in am-TiO2. Water-splitting based on artificial photocatalysis at semiconductor-water interfaces represents a promising technology for the clean production of fuel. The main hindrance to the success of such a technology is the lack of highly efficient catalysts. When searching for the ideal material, the alignment of the redox levels at semiconductor-water interfaces is considered as an important criterion to assess the photocatalytic capacity of candidate semiconductor. In this work, we determine the band alignment between various semiconductors and liquid water
A Review on Binder Jet Additive Manufacturing of 316L Stainless Steel

Binder jet additive manufacturing enables the production of complex components for numerous applications. Binder jetting is the only powder bed additive manufacturing process that is not fusion-based, thus manufactured parts have no residual stresses as opposed to laser-based additive manufacturing processes. Binder jet technology can be adopted for the production of various small and large metallic parts for specific applications, including in the biomedical and energy sectors, at a lower cost and shorter lead time. One of the most well-known types of stainless steels for various industries is 316L, which has been extensively manufactured using binder jet technology. Binder jet manufactured 316L parts have obtained near full density and, in some cases, similar mechanical properties compared to conventionally manufactured parts. This article introduces methods, principles, and applications of binder jetting of SS 316L. Details of binder jetting processes, including powder characteristics (shape and size), binder properties (binder chemistry and droplet formation mechanism), printing process parameters (such as layer thickness, binder saturation, drying time), and post-processing sintering mechanism and densification processes, are carefully reviewed. Furthermore, critical factors in the selection of feedstock, printing parameters, sintering temperature, time, atmosphere, and heating rate of 316L binder jet manufactured parts are highlighted and summarized. Finally, the above-mentioned processing parameters are correlated with final density and mechanical properties of 316L components to establish a guideline on feedstock selection and process parameters optimization to achieve desired density, structure and properties for various applications.
A liderança no contexto das redes organizacionais

Esta tese foi desenvolvida no Nucleo de Relacoes de Trabalho e Tecnologias de Gestao (NURTEG) da Universidade Federal de Minas Gerais (UFMG), tendo como pressuposto basico que, no ambiente das redes organizacionais, qualquer que seja a sua natureza, ha uma manifestacao diferenciada da lideranca em funcao dos arranjos sociais,estruturais e organizacionais que sao elaborados no sentido de satisfazer objetivos comuns aos participantes da rede. Dessa forma, o problema da pesquisa foi: como se articulam o discurso, a pratica e o desenvolvimento da lideranca no contexto das redes organizacionais,considerando-se que a racionalidade predominante ainda e a instrumental? O objetivo foi realizar uma analise acerca da emergencia da lideranca no contexto das redes organizacionais, incorporando contribuicoes multidisciplinares, da sociologia, antropologia, psicologia,simbolismo e administracao, e estabelecendo algumas especificidades da lideranca nos rearranjos e transformacoes organizacionais. A abordagem metodologica buscou um aparato qualitativo a partir de dados obtidos em entrevistas realizadas com lideres nas seguintes redes: uma, organizada pela Superintendencia de Limpeza Urbana (SLU) da Prefeitura de Belo Horizonte/MG e Associacao de Catadores de Papel e Reciclaveis; a outra rede e organizada pelo Comite de Fomento Industrial de Camacari (COFIC) no Polo Petroquimico de Camacari/Bahia. A abordagem teorica convergiu para teoria das organizacoes e estrutura, como suporte para migrar, logo em seguida, para o conteudo sobre redes organizacionais. Na passagem do conteudo de redes para lideranca, foram abordados temas relacionados ao institucionalismo e rizomas. O referencial teorico em lideranca perpassou os textos tradicionais sobre o assunto e os de analises mais criticas. Os resultados da pesquisa realizada indicam o surgimento de uma lideranca mais ancorada na realidade do cotidiano organizacional, social, economico e politico, sobretudo pelo entendimento da necessidade de reducao da distância entre lider e liderados. O estudo da lideranca no contexto das redes organizacionais assevera a percepcao de que o conteudo da literatura tradicional em redes elideranca apresenta um afastamento em relacao a realidade vivenciada.
Cifração e autenticação utilizando funções fisicamente não clonáveis (PUFs)

This work presents applications based on a recent primitive called Physically Unclonable Functions (PUFs), and how they can be used to establish security properties. In this work, PUFs are employed to construct a block cipher and authenticator, where the rst is constructed from a Luby-Racko cipher with 4 rounds involving PUFs and universal hash functions. The cipher improves the state of the art of PUF-based encryption in two aspects: security and size of the resulting ciphertext. The second, a Message Authentication Code (MAC) is built by the combination of a classic xed-size MAC with a universal hash function. In both cases, security analysis are provided considering standard notions in the literature. Since the PUFs implicitly encode cryptographic keys, the techniques presented can be used in authenticated encryption schemes of hard drives or mobile devices, increasing resistance against leakage of key bits. Besides the proposed construction of a cipher and an authenticator, we propose an authentication protocol for banking applications combining PUFs with protocols for Password-based Authenticated Key Exchange (PAKE). The resulting protocol provides mutual authentication between client and server and establishes a session key between the authenticated parties, important features that were not found simultaneously in the literature of PUF-based authentication. This combination improves the state of the art, ensuring that the session key is only available to legitimate holders of the PUF, reducing the possibility of leaking secrets stored explicitly. The protocol supports multiple authentication factors and provides protection against o ine dictionary attacks on the password authentication. Moreover, it satis es the usual security notions when the PUF output is unpredictable, and allows the client to notify the server in case of emergency.
Effects of L1 orthography and L1 phonology on L2 English pronunciation

Recent research has revealed the effects of orthography on the pronunciation of consonant durations in the L2 English of L1 Italian speakers (e.g. the [p] in floppy being pronounced as longer than in copy). In this paper we compared this orthographic effect with an orthography-independent effect of L1 phonology, namely VOT. We measured closure durations and VOT for plosives produced by 30 learners of L2 English in Italy, 30 Italian late bilingual speakers of L2 English living in the UK, and 30 native English speakers. While VOT values produced by late bilinguals differed significantly from those produced by learners, closure durations were similar across the two groups. Additionally, L1 Italian VOT values proved that late bilinguals adapted VOT in L2 English by a larger extent than learners. It appears that the effects of orthography on L2 consonant duration can be more resistant to naturalistic L2 exposure than orthography-independent effects of L1 phonology.