The study is focused on the phenomenon of diffusion of water through the shells of two coconut species (coconut nucifera) of Cameroun. The kinetics absorption of water was studied experimentally by the gravimetric met...The study is focused on the phenomenon of diffusion of water through the shells of two coconut species (coconut nucifera) of Cameroun. The kinetics absorption of water was studied experimentally by the gravimetric method with discontinuous control of the mass of the samples at the temperature of 23℃. The mature coconut shells were cleaned mechanically, cut in a spherical shape and placed in a drying oven with 105℃ for 4 hours before being plunged in distilled water at 23℃. This study made it possible not only to determine the rate of water absorbed, but also to model the water kinetic absorption of the shells. Of the two models tested (Peleg and Page), the Page model predicted very well the experimental data. The Fick law made it possible to evaluate the effective diffusivity coefficients at the initial and final phases of absorption. The effective diffusivity coefficient was given from the Arrhenius equation.展开更多
Water diffusion of two species of coconut shells (CS) nucifera from Cameroon, in the case of drying, was experimentally studied. The experiment was done with the aid of an oven, by the method of gravimetric batch cont...Water diffusion of two species of coconut shells (CS) nucifera from Cameroon, in the case of drying, was experimentally studied. The experiment was done with the aid of an oven, by the method of gravimetric batch control of the mass of the test samples with the temperatures varied from 70° to 180° Celsius. The shells of mature coconuts from two species were conserved in the laboratory at a temperature ranging between 20° and 23° Celsius for two months before being mechanically cleaned. This study allows not only the determination of the water content of the shells, but also the identification of the drying model. It is thus from the ten model tests, and the statistical analysis shows that the Midilli model best predicted this drying phenomenon. The coefficient of effective diffusion was determined at different temperatures which permitted the evaluation of the activation energy per the Arrhenius equation.展开更多
The present work is focused on better understanding of the interfacial interactions of SBA-15 mesoporous silica particles with flax fibers. In order to overcome the inherent complexity of flax fiber surface compositio...The present work is focused on better understanding of the interfacial interactions of SBA-15 mesoporous silica particles with flax fibers. In order to overcome the inherent complexity of flax fiber surface composition we have prepared model polysaccharide surfaces representing the main component of the flax fibers, e.g. cellulose, polygalacturonic acid (PGUA), and xyloglucan (XG) with thicknesses of about 200 nm, 100 nm, and 110 nm, respectively. The ξ-potential measurements of both silica and polysaccharides were performed in aqueous solutions as a function of pH and ionic strength. ξ-potential, AFM and SEM results supported the important role of electrostatic interactions in the silica adsorption on polysaccharide surfaces, since silica adsorption increased remarkably with ionic strength. The adsorption density of the SBA-15 onto the various polysaccharides was Cellulose > PGUA > XG, and the maximum was observed at pH = 4. Urea used as hydrogen bonds breaker reduced significantly the adsorption of SBA-15 on the polysaccharide surfaces, which highlighted the significant contribution of hydrogen bonding in the adsorption process. It was observed that most adsorbed SBA-15 particles were resistant to ultrasonic washing, which revealed their strong irreversible adsorption. Finally, direct adsorption experiments on both raw and treated real flax fibers yielded results consistent with those of model surfaces showing the important role of the surface fibers treatments on the improvement of the interfacial adhesion of the silica particles with flax fibers. The remarkable affinity of the SBA-15 particles with treated flax fibers is encouraging to design superinsulators composites with tuneable mechanical performances.展开更多
This main contribution of this work is to propose a new approach based on a structure of MLPs （multi-layer perceptrons） for identifying current harmonics in low power distribution systems. In this approach, MLPs are...This main contribution of this work is to propose a new approach based on a structure of MLPs （multi-layer perceptrons） for identifying current harmonics in low power distribution systems. In this approach, MLPs are proposed and trained with signal sets that arc generated from real harmonic waveforms. After training, each trained MLP is able to identify the two coefficients of each harmonic term of the input signal. The effectiveness of the new approach is evaluated by two experiments and is also compared to another recent MLP method. Experimental results show that the proposed MLPs approach enables to identify effectively the amplitudes of harmonic terms from the signals under noisy condition. The new approach can be applied in harmonic compensation strategies with an active power filter to ensure power quality issues in electrical power systems.展开更多
Finance,supply chains,healthcare,and energy have an increasing demand for secure transactions and data exchange.Permissioned blockchains fulfilled this need thanks to the consensus protocol that ensures that participa...Finance,supply chains,healthcare,and energy have an increasing demand for secure transactions and data exchange.Permissioned blockchains fulfilled this need thanks to the consensus protocol that ensures that participants agree on a common value.One of the most widely used protocols in private blockchains is the Practical Byzantine Fault Tolerance(PBFT),which tolerates up to one-third of Byzantine nodes,performs within partially synchronous systems,and has superior throughput compared to other protocols.It has,however,an important bandwidth consumption:2N(N-1)messages are exchanged in a system composed of𝑁nodes to validate only one block.It is possible to reduce the number of consensus participants by restricting the validation process to nodes that have demonstrated high levels of security,rapidity,and availability.In this paper,we propose the first database that traces the behavior of nodes within a system that performs PBFT consensus.It reflects their level of security,rapidity,and availability throughout the consensus.We first investigate different Single-Task Learning(STL)techniques to classify the nodes within our dataset.Then,using Multi-Task Learning(MTL)techniques,the results are much more interesting,with classification accuracies over 98%.Integrating node classification as a preliminary step to the PBFT protocol optimizes the consensus.In the best cases,it is able to reduce the latency by up to 94%and the communication traffic by up to 99%.展开更多
In this paper, we study non-abelian extensions of 3-Lie algebras through Maurer-Cartan elements. We show that there is a one-to-one correspondence between isomorphism classes of non-abelian extensions of 3-Lie algebra...In this paper, we study non-abelian extensions of 3-Lie algebras through Maurer-Cartan elements. We show that there is a one-to-one correspondence between isomorphism classes of non-abelian extensions of 3-Lie algebras and equivalence classes of Maurer-Cartan elements in a DGLA. The structure of the Leibniz algebra on the space of fundamental objects is also analyzed.展开更多
文摘The study is focused on the phenomenon of diffusion of water through the shells of two coconut species (coconut nucifera) of Cameroun. The kinetics absorption of water was studied experimentally by the gravimetric method with discontinuous control of the mass of the samples at the temperature of 23℃. The mature coconut shells were cleaned mechanically, cut in a spherical shape and placed in a drying oven with 105℃ for 4 hours before being plunged in distilled water at 23℃. This study made it possible not only to determine the rate of water absorbed, but also to model the water kinetic absorption of the shells. Of the two models tested (Peleg and Page), the Page model predicted very well the experimental data. The Fick law made it possible to evaluate the effective diffusivity coefficients at the initial and final phases of absorption. The effective diffusivity coefficient was given from the Arrhenius equation.
文摘Water diffusion of two species of coconut shells (CS) nucifera from Cameroon, in the case of drying, was experimentally studied. The experiment was done with the aid of an oven, by the method of gravimetric batch control of the mass of the test samples with the temperatures varied from 70° to 180° Celsius. The shells of mature coconuts from two species were conserved in the laboratory at a temperature ranging between 20° and 23° Celsius for two months before being mechanically cleaned. This study allows not only the determination of the water content of the shells, but also the identification of the drying model. It is thus from the ten model tests, and the statistical analysis shows that the Midilli model best predicted this drying phenomenon. The coefficient of effective diffusion was determined at different temperatures which permitted the evaluation of the activation energy per the Arrhenius equation.
文摘The present work is focused on better understanding of the interfacial interactions of SBA-15 mesoporous silica particles with flax fibers. In order to overcome the inherent complexity of flax fiber surface composition we have prepared model polysaccharide surfaces representing the main component of the flax fibers, e.g. cellulose, polygalacturonic acid (PGUA), and xyloglucan (XG) with thicknesses of about 200 nm, 100 nm, and 110 nm, respectively. The ξ-potential measurements of both silica and polysaccharides were performed in aqueous solutions as a function of pH and ionic strength. ξ-potential, AFM and SEM results supported the important role of electrostatic interactions in the silica adsorption on polysaccharide surfaces, since silica adsorption increased remarkably with ionic strength. The adsorption density of the SBA-15 onto the various polysaccharides was Cellulose > PGUA > XG, and the maximum was observed at pH = 4. Urea used as hydrogen bonds breaker reduced significantly the adsorption of SBA-15 on the polysaccharide surfaces, which highlighted the significant contribution of hydrogen bonding in the adsorption process. It was observed that most adsorbed SBA-15 particles were resistant to ultrasonic washing, which revealed their strong irreversible adsorption. Finally, direct adsorption experiments on both raw and treated real flax fibers yielded results consistent with those of model surfaces showing the important role of the surface fibers treatments on the improvement of the interfacial adhesion of the silica particles with flax fibers. The remarkable affinity of the SBA-15 particles with treated flax fibers is encouraging to design superinsulators composites with tuneable mechanical performances.
文摘This main contribution of this work is to propose a new approach based on a structure of MLPs （multi-layer perceptrons） for identifying current harmonics in low power distribution systems. In this approach, MLPs are proposed and trained with signal sets that arc generated from real harmonic waveforms. After training, each trained MLP is able to identify the two coefficients of each harmonic term of the input signal. The effectiveness of the new approach is evaluated by two experiments and is also compared to another recent MLP method. Experimental results show that the proposed MLPs approach enables to identify effectively the amplitudes of harmonic terms from the signals under noisy condition. The new approach can be applied in harmonic compensation strategies with an active power filter to ensure power quality issues in electrical power systems.
文摘Finance,supply chains,healthcare,and energy have an increasing demand for secure transactions and data exchange.Permissioned blockchains fulfilled this need thanks to the consensus protocol that ensures that participants agree on a common value.One of the most widely used protocols in private blockchains is the Practical Byzantine Fault Tolerance(PBFT),which tolerates up to one-third of Byzantine nodes,performs within partially synchronous systems,and has superior throughput compared to other protocols.It has,however,an important bandwidth consumption:2N(N-1)messages are exchanged in a system composed of𝑁nodes to validate only one block.It is possible to reduce the number of consensus participants by restricting the validation process to nodes that have demonstrated high levels of security,rapidity,and availability.In this paper,we propose the first database that traces the behavior of nodes within a system that performs PBFT consensus.It reflects their level of security,rapidity,and availability throughout the consensus.We first investigate different Single-Task Learning(STL)techniques to classify the nodes within our dataset.Then,using Multi-Task Learning(MTL)techniques,the results are much more interesting,with classification accuracies over 98%.Integrating node classification as a preliminary step to the PBFT protocol optimizes the consensus.In the best cases,it is able to reduce the latency by up to 94%and the communication traffic by up to 99%.
基金Supported by National Natural Science Foundation of China under Grant No.11471139National Natural Science Foundation of Jilin Province under Grant No.20170101050JC
文摘In this paper, we study non-abelian extensions of 3-Lie algebras through Maurer-Cartan elements. We show that there is a one-to-one correspondence between isomorphism classes of non-abelian extensions of 3-Lie algebras and equivalence classes of Maurer-Cartan elements in a DGLA. The structure of the Leibniz algebra on the space of fundamental objects is also analyzed.
