Fabrication of TiO2 nanofibre photoelectrode for photoelectrochemical cells

The TiO2 nanofibres (NFs), prepared with the electrospinning method, acted as the photoanode in a photoelectrochemical cell (PEC) for hydrogen generation. The fabrication parameters of Ti/PVP (polyvinylpyrrolidone) fibres were determined with the field-emission scanning electron microscopy (FE-SEM) method. The structure and morphology of the TiO2 fibres were characterized by using X-ray diffraction (XRD), FE-SEM, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HR-TEM). The average diameter of the TiO2 fibre is 132 ± 16 nm. A three-electrode potentiostat was used to study the photoelectrochemical properties of the photoanode. The density photocurrent reached the saturation value of 80 mA·cm–2 at 0.2 V under the irradiation of a Xenon lamp

Optimization of Design Procedure for Column-base Connections according to EN 1993-1-8:2006

The stiffness and the strength of a column-base connection have significant impacts on the behavior of a steel frame. The paper develops an interaction curve between moment and axial force for the column-base connections according to EN 1993-1-8:2006 with the variation of the base plate thickness and the bolt diameter. This is the fundamental base to determine the ultimate strength of a column-base plate that allows the designers to estimate the strength of column-base connections. This research investigates the relationship between the base plate thickness, the bolt diameter, and the moment strength of the column-base plate with a specific axial force to select an optimum solution. Also, the initial rotational stiffness is determined under a specific axial load and varied moments that satisfy the ultimate limit state. The relationship between moment–rotation is subsequently performed with the variation of the base plate thickness or the bolt diameter. The design procedure is proposed based on moment-axial force interaction curves and moment-rotation curves. This allows for optimizing the column-base connection from proper selections of base plate dimensions and bolt diameters

New primitives of controlled elements F2/4 for block ciphers

This paper develops the cipher design approach based on the use of data-dependent operations (DDOs). A new class of DDO based on the advanced controlled elements (CEs) is introduced, which is proven well suited to hardware implementations for FPGA devices. To increase the hardware implementation efficiency of block ciphers, while using contemporary FPGA devices there is proposed an approach to synthesis of fast block ciphers, which uses the substitution-permutation network constructed on the basis of the controlled elements F2/4 implementing the 2 x 2 substitutions under control of the four-bit vector. There are proposed criteria for selecting elements F2/4 and results on investigating their main cryptographic properties. It is designed a new fast 128-bit block cipher MM-128 that uses the elements F2/4 as elementary building block. The cipher possesses higher performance and requires less hardware resources for its implementation on the bases of FPGA devices than the known block ciphers. There are presented result on differential analysis of the cipher MM-12

Condensation Heat Transfer of R410A Inside Multiport Minichannels with Different Cross-sectional Geometry

Condensation heat transfer of R410a in a multiport mini-channels tubes with different cross-sectional geometry is experimentally investigated. Three tubes with aspect ratio of 0.395, 0.385 and 0.446, and hydraulic diameters of 1.147 mm, 1.135 mm and 0.846 mm with number of channels (7, 11 and 18) are tested in this study. The experimented range of heat flux is from 3 to 15 kW/m2, mass flux from 50 to 500 kg/m2s. The data show that the heat transfer coefficient increases with heat flux, mass flux and vapor quality. A performance comparison was conducted among the 3 tested tubes and it was found out that the number of channels increases heat transfer coefficient significantly at low heat flux and mass flux, while this effect is damped at higher heat/mass flux condition. In addition, it was found that heat transfer in small hydraulic diameter and high aspect ratio channels deteriorated. Possible mechanism to this deterioration is proposed. Finally, a new correlation is developed to predict the heat transfer coefficient of R410a in a multiport mini-channels tube

NEW RECORD OF CAMELLIA SECT. CAMELLIA (THEACEAE) FOR THE FLORA OF VIETNAM

This study provides color illustrations and describes the morphological characteristics and distribution of Camellia pitardii and Camellia mairei var. lapidea, species formerly considered endemic to China but recently discovered and recorded in the flora of Vietnam

Unsupervised Detection of Anomalous Sound for Machine Condition Monitoring using Fully Connected U-Net

Anomaly detection in the sound from machines is an important task in machine monitoring. An autoencoder architecture based on the reconstruction error using a log-Mel spectrogram feature is a conventional approach for this domain. However, because of the non-stationary nature of some sounds from the target machine, such a conventional approach does not perform well in those circumstances. In this paper, we propose a novel approach regarding the choice of used features and a new auto-encoder architecture. We created the Mixed Feature, which is a mixture of different sound representations, and a new deep learning method called Fully-Connected U-Net, a form of autoencoder architecture. With experiments on the same dataset as the baseline system, using the same architecture for all types of machines, the experimental results showed that our methods outperformed the baseline system in terms of the AUC and pAUC evaluation metrics. The optimized model achieved 83.38% AUC and 64.51% pAUC on average overall machine types on the developed dataset and outperformed the published baseline by 13.43% AUC and 8.13% pAUC

Elastic and thermodynamic properties of the major clinker phases of Portland cement: Insights from first principles calculations

Portland based cement is one of the most popular materials used in the civil and construction applications. Reliable computational methods to provide an insight into the underlying mechanics of the major phases of this material are of great interest for cement design. The present work investigated the performance of density functional theory (DFT) calculations using the PBE-D2 method to predict the mechanical, thermodynamic properties of four major phases namely Alite C3S, Belite C2S, tricalcium aluminate C3A and tetracalcium aluminoferrite C4AF. The calculated elastic properties were in a good agreement with available experimental data. In addition, a deeper insight into the electron density of state, spin-polarization, atomic charge, as well as free energy and entropy properties were also presented. Further development is necessary to improve the established DFT models for predicting the mechanical properties of the ferrite phase of Portland clinker.publishedVersio

Optimizing Boiler Efficiency by Data Mining Teciques: A Case Study

In a fertilizer plant, the steam boiler is the most important component. In order to keep the plant operating in the effective mode, the boiler efficiency must be observed continuously by several operators. When the trend of the boiler efficiency is going down, they may adjust the controlling parameters of the boiler to increase its efficiency. Since manual operation usually leads to unex-pectedly mistakes and hurts the efficiency of the system, we build an information system that plays the role of the operators in observing the boiler and adjusting the controlling parameters to stabilize the boiler efficiency. In this paper, we first introduce the architecture of the information system. We then present how to apply K-means and Fuzzy C-means algorithms to derive a knowledge base from the historical operational data of the boiler. Next, recurrent fuzzy neural network is employed to build a boiler simulator for evaluating which tuple of input values is the best optimal and then automatically adjusting controlling inputs of the boiler by the optimal val-ues. In order to prove the effectiveness of our system, we deployed it at Phu My Fertilizer Plant equipped with MARCHI boiler having capacity of 76-84 ton/h. We found that our system have improved the boiler efficiency about 0.28-1.12% in average and brought benefit about 57.000 USD/year to the Phu My Fertilizer Plant

Simulation Study of Mid-infrared Supercontinuum Generation at Normal Dispersion Regime in Chalcogenide Suspended-core Fiber Infiltrated with Water

We report simulation results of supercontinuum generation in the suspended-core optical fibers made of chalcogenide (As2S3) infiltrated with water at mid-infrared wavelength range. Applying water-hole instead of the air-hole in fibers allows improving the dispersion characteristics, hence, contributing to supercontinuum generations. As a result, the broadband supercontinuum generation ranging from 1177 nm to 2629 nm was achieved in a 10 cm fiber by utilizing very low input pulse energy of 0.01 nJ and pulse duration of 100 fs at 1920 nm wavelength