Nano iron oxide (Fe2O3)/carbon black electrodes as electrode material for electrochemical capacitors: Effect of the nanoparticles dispersion quality

In the present study, nano Fe₂O₃/carbon black electrodes are proposed for electrochemical capacitors and the effect of nanoparticles dispersion quality on the surface morphology, nature and electrochemical properties of the electrodes are investigated. Mechanical pressing is accompanied by different mixing (mechanical and sonication) processes to prepare the electrode. Electrochemical properties of the produced nanocomposites are studied using cyclic voltammetry and electrochemical impedance spectroscopy tests in 2 M KCl electrolyte. Scanning electron microscopy is used to characterize the microstructure and the nature of the nanoparticles on the nanocomposites produced. Results obtained show that the sonicated and unsonicated 10:80:10 (CB:Fe₂O₃:PTFE) electrodes have specific capacitance of 22.02 and 22.35 F g⁻¹ respectively, at scan rate of 10 mV s⁻¹. Sonication process breaks the agglomerated particles and disperses them on the electrode surface, uniformly. This increases the specific surface area and the electrical resistance of the electrodes. The sonicated electrodes show a higher charge separation capability at electrolyte/electrode interfaces, lower ratio of outer to total charge (q_O*/q_T*) of 0.13 and lower current response at end potentials. Energy density was increased after the sonication process from 0.686 to 1.498 (Wh kg⁻¹). Charge/discharge cycling results confirmed that the uniform dispersion of active material on the electrode surface postpones the electrolyte decomposition and improves the electrical conductivity during cycling.     

Durability of recycled aggregate concrete designed with equivalent mortar volume method

Results of a comprehensive investigation about the durability of structural-grade concrete made with recycled concrete aggregate (RCA) are presented. The RCA-concrete mixes were proportioned using a new concrete mix design method, termed the equivalent mortar volume (EMV) method. The EMV method is based on the hypothesis that RCA is a composite material comprising mortar and natural aggregate; therefore, when proportioning a concrete mixture containing RCA, one must account for the relative amount and properties of each the two components and adjust both the fresh coarse aggregate and fresh paste content of the mix accordingly. Tests were conducted to study the freeze–thaw, chloride penetration and carbonation resistances of the mixes proportioned by the EMV method and by the conventional method. Results of the test showed that RCA-concrete mixes proportioned by the EMV method have higher resistance to freeze–thaw action, chloride penetration and carbonation than those designed with the conventional method, and they satisfy the current requirements for concrete exposed to severe environments.     

A novel deep network architecture for reconstructing RGB facial images from thermal for face recognition

Multimedia Tools and Applications - This work proposes a fully convolutional network architecture for RGB face image generation from a given input thermal face image to be applied in face...     

Going deeper in hidden sadness recognition using spontaneous micro expressions database

Multimedia Tools and Applications - Recognition of facial micro-expressions (MEs), which indicates conscious or unconscious suppressing of true emotions, is still a challenging task in the...     

Combining a maintenance center M/M/c/m queue into the economic production quantity model with stochastic machine breakdowns and repair

This article considers a production system in which “m” identical machines produce nonidentical products at production rates. Products made by each machine are on the other hand consumed at a specific demand rate. Machines may be affected by unwanted breakdowns. Machines break down according to a Poisson distribution with equal rates and the failed machines are sent to maintenance center for repair which is consisted of “c” servers or servicemen. However, Number of machines is greater than number of servicemen (m > c). Hence, if the number of failed machines is greater than that of servicemen, the machines have to be put in a queue. Machines are put in one queue with the order of queue being FCFS. The queue has a typical M/M/c/m system. If machines are broken down during production, shortage will occur. This problem has been considered to obtain a single production cycle for the machines and an optimum number of the servers such that costs are minimized. For this purpose, distribution of waiting time for machines in repair center is calculated and a cost function is formed. Steepest descent and direct search methods are applied in this work to obtain optimal production cycle and maintenance servers, respectively. The proposed methods are studied using a comprehensive example.     

Value-focused assessment of information system security in organizations

Abstract.  Information system (IS) security continues to present a challenge for executives and professionals. A large part of IS security research is technical in nature with limited consideration of people and organizational issues. The study presented in this paper adopts a broader perspective and presents an understanding of IS security in terms of the values of people from an organizational perspective. It uses the value-focused thinking approach to identify 'fundamental' objectives for IS security and 'means' of achieving them in an organization. Data for the study were collected through in-depth interviews with 103 managers about their values in managing IS security. Interview results suggest 86 objectives that are essential in managing IS security. The 86 objectives are organized into 25 clusters of nine fundamental and 16 means categories. These results are validated by a panel of seven IS security experts. The findings suggest that for maintaining IS security in organizations, it is necessary to go beyond technical considerations and adopt organizationally grounded principles and values.     

Artificial neural networks application to predict the ultimate tensile strength of X70 pipeline steels

The paper presents some results of the research connected with the development of new approach based on the artificial neural network (ANN) of predicting the ultimate tensile strength of the API X70 steels after thermomechanical treatment. The independent variables in the model are chemical compositions (carbon equivalent), based upon the International Institute of Welding equation (CE_IIW), the carbon equivalent, based upon the chemical portion of the Ito-Bessyo carbon equivalent equation (CE_Pcm), the sum of the niobium, vanadium and titanium concentrations (VTiNb), the sum of the niobium and vanadium concentrations (NbV), the sum of the chromium, molybdenum, nickel and copper concentrations (CrMoNiCu), Charpy impact energy at ?10 °C (CVN) and yield strength at 0.005 offset (YS). For purpose of constructing these models, 104 different data were gathered from the experimental results. The data used in the ANN model is arranged in a format of seven input parameters that cover the chemical compositions, yield stress and Charpy impact energy, and output parameter which is ultimate tensile strength. In this model, the training, validation and testing results in the ANN have shown strong potential for prediction of relations between chemical compositions and mechanical properties of API X70 steels.     

Suppression of nonlinear regenerative chatter in milling process via robust optimal control

During the milling process, self-excited vibration or chatter adversely affects tool life, surface quality and productivity rate. In this paper, nonlinear cutting forces of milling process are considered as a function of chip thickness with a complete third order polynomial (instead of the common linear dependency). An optimal control strategy is developed for chatter suppression of the system described through nonlinear delay differential equations. Counterbalance forces exerted by actuators in x and y directions are the control inputs. For optimal control problem, an appropriate performance index is defined such that the regenerative chatter is suppressed while control efforts are minimized. Optimal control law is determined based on variation of extremals algorithm. Results show that under unstable machining conditions, regenerative chatter is suppressed effectively after applying the optimal control strategy. In addition, optimal controller guarantees robust performance of the process in the presence of model parametric uncertainties.