Current Contents / Engineering, Computing & Technology

Hydrogen is the new age alternative energy source to combat energy demand and climate change. Storage of hydrogen is vital for a nation’s growth. Works of literature provide different methods for storing the produced hydrogen, and the rational selection of a viable method is crucial for promoting sustainability and green practices. Typically, hydrogen storage is associated with diverse sustainable and circular economy (SCE) criteria. As a result, the authors consider the situation a multi-criteria decision-making (MCDM) problem. Studies infer that previous models for hydrogen storage method (HSM) selection (i) do not consider preferences in the natural language form; (ii) weights of experts are not methodically determined; (iii) hesitation of experts during criteria weight assessment is not effectively explored; and (iv) three-stage solution of a suitable selection of HSM is unexplored. Driven by these gaps, in this paper, authors put forward a new integrated framework, which considers double hierarchy linguistic information for rating, criteria importance through inter-criteria correlation (CRITIC) for expert weight calculation, evidence-based Bayesian method for criteria weight estimation, and combined compromise solution (CoCoSo) for ranking HSMs. The applicability of the developed framework is testified by using a case example of HSM selection in India. Sensitivity and comparative analysis reveal the merits and limitations of the developed framework.

The interaction of the virus with the alveoli cell is examined, where the virus enters the lungs through the human airways after human inhalation. The virus selected was close to SARS-CoV-2. The numerical experiment was performed using the discrete element method. The results show the change in force, velocity, and displacement over time. The model evaluates the interaction of the capsid and spikes with the alveoli cell surface. The initial parameters, such as initial velocity, size, and data required to describe the interaction, were selected based on known physical experiments. The mechanism of energy dissipation associated with adhesion is considered.

Continuous relative phase (CRP) is a measure of coordination between two joints, and CRP based analysis is being used to characterise joint or segmental coordination during gait. Postural instability or balancing issue is one of the major motor symptoms of Parkinson’s Disease (PD). This study aimed to use CRP variables to distinguish between PD, healthy control (CO) groups, and PD groups divided according to clinical evaluations. The subjects were separated into two groups: healthy controls and Parkinson’s disease subjects. Additionally, the PD group was subdivided according to the unified Parkinson disease rating scale (UPDRS) scores: UPDRS 0 and UPDRS 1. Each subject performed the designated walking motor task three times. Four inertial measurement units (IMU) were used to measure movement of the lower limbs. Statistically significant differences in CRP mean, deviation phase (DP), and root mean square CRP (CRPRMS) were found for PD vs CO (right stance, right swing, right mid-stance) and UPDRS 0 vs UPDRS 1 (right stride, left stride, right swing). CRP can be used to separate PD and CO groups, and groups subdivided based on UPDRS score.

Intense sound levels produced by engineering equipment have become an acute issue. As most of engineering equipment require air supply, exhaust and good ventilation, it is not possible to control the noise by covering them with tight hoods. Louver with blades covered with acoustic materials and gaps that enable free circulation of air are used to this end. Three louver configurations were tested in the semi-anechoic chamber: bare metal louver blades, louver with blades covered with 20-mm-thick polystyrene foam slabs on both sides, and louver with blades covered with 15-mm-thick glass wool slab. According to the test results, louver with blades covered with glass wool slab demonstrated the best noise attenuation characteristics. The reduction of equivalent sound pressure level subject to blade inclination angle was from 10.8 to 12.5 dB. Sound pressure level reduction by louver with blades covered with polystyrene foam slabs was weaker: the reduction of equivalent sound pressure level was from 5.4 to 8.4 dB. Louver with blades not covered with any acoustic material demonstrated the least noise attenuation result from 1.9 to 3.9 dB. © 2020 Institute of Noise Control Engineering.

Sharp falls or explosive growths in exchange markets, whether expected or not, generates new challenges for investors who want to protect their investments or achieve an optimum benefit during and after the turmoil. An anomaly of the exchange market, instigated by the Swiss National Bank, occurred when the Swiss Franc decoupled from the euro unexpectedly. The United Kingdom (UK) vote to withdraw from the European Union (Brexit), in contrast, was feared but expected. A comparison of the consequences of the anomalies gives us an unprecedented opportunity to investigate prediction capabilities of the EVOLINO Recurrent Neural Network Ensemble (ERNN) model following an anomaly. By introducing this new information to the ERNN model and analyzing its response, we increase investor resources during large exchange rate fluctuations; this will provide them with additional information that will help them construct different portfolios. Reaction to the anomaly was visible only after the anomaly occurred, this is when the model began to acquire data influenced by the extreme change. Comparing different strategies which are related or unrelated to the anomaly and orthogonal or not orthogonal for conservative, moderate, or aggressive trading shows that in order to profit from the anomaly, speculation depends on prediction-accuracy and on the sets of exchange-rate associated with the anomaly.

In this paper, we present a novel image steganography method which is based on color palette transformation in color space. Most of the existing image steganography methods modify separate image pixels, and random noise appears in the image. By proposing a method, which changes the color palette of the image (all pixels of the same color will be changed to the same color), we achieve a higher user perception. Presented comparison of stegoimage quality metrics with other image steganography methods proved the new method is one of the best according to Structural Similarity Index (SSIM) and Peak Signal Noise Ratio (PSNR) values. The capability is average among other methods, but our method has a bigger capacity among methods with better SSIM and PSNR values. The color and pixel capability can be increased by using standard or adaptive color palette images with smoothing, but it will increase the embedding identification possibility.

Engineering project networks (EPNs), as digitally mediated units whose team members are scattered across different organizations/locations, have become the norm for construction project teams. In EPNs, virtuality captures various forms of boundaries among team members and influences major dimensions of team functioning and outcomes. Despite this importance, investigating the role of virtuality on the functional performance of EPNs has remained an unexplored area. Through a multidisciplinary review of literature, a theoretical model has been created to conceptualize the fabric of links between virtuality and effectiveness in EPNs. The theoretical basis of the model is the Big Five theory of team effectiveness. The model has been evaluated using empirical data collected from 285 completed questionnaires, and analyzed through the use of partial least squares structural equation modeling (PLS-SEM) technique. Quantification of associations reveals that virtuality significantly affects effectiveness in teams by manipulating several mediators. However, the level of influence of virtuality on these mediators, and eventually effectiveness, is much lower than previously assumed by current literature. This study goes beyond existing studies, presenting the first quantified model of virtuality applicable to any type of EPN in the construction context.

This work deals with the features of the structure of combined ZrC/Ni-ultradisperse diamonds (UDD) coating synthesized by electroplating and cathode arc evaporation physical vapor deposition (CAE-PVD) techniques on the tungsten carbide WC – 2 wt% Co on cutting inserts to improve tool life. The microstructure, phase composition, and micro-scratch test analysis of the ZrC/Ni-UDD coating were studied. The ZrC/Ni-UDD coating consists of separate phases of zirconium carbide ZrC, a-Ni, and Ni-UDD phase. The surface morphology of the coating shows a pattern with pits, pores, and particles. Separated nanodiamond particles are present in the pores of the combined coating. Therefore, the structure of the bottom layer of Ni-UDD affects the morphology of the surface of the ZrC/Ni-UDD coating. The obtained value of the critical loads on the scratch track of the coating in 26 N proves a sufficiently high value of the adhesion strength of the intermediate Ni-UDD-layer with hard alloy of WC-Co substrate. Due to their unique structure ZrC/Ni-UDD-coatings can be used to increase the durability period of a wood-cutting milling tool for cutting chipboard by CNC machines.

The ventilation heat recovery exchanger (HRE) for low energy buildings is becoming one of the important heat transformers in the HVAC systems. The purpose of this paper is to develop the possibilities of exergy analysis for the HRE, when the reference temperature (RT) is variable. The method was prepared through consideration of the exergy flow direction changes, when variable RT was placed below, above and across the operating temperature of working fluids. By using the coenthalpy diagrams, there were obtained three functional exergy efficiencies which had greater sensitivity than universal exergy efficiency. The prepared solution allows the reliable using of the ubiquitous thermodynamic (exergy) analysis for energy chain in the HVAC systems. This methodology may be developed for other heat exchangers with different mass flows, operated at near-environmental temperatures. The results could have a practical application for designing the HVAC systems and implementing their exergy optimum operation controls.

Ventilation and air conditioning systems are emerging as the major energy consumers in low energy buildings. The objective of this paper is to present new methodology for assessment of Air Handling Units (AHUs) taking into account the variations of reference temperature. The methodology using the concept of coenthalpy, developed for heat exchangers and published by the authors previously has been used. Four AHUs that comprise energy transfer devices, such as: Water-to-Air Heater (WAH), Heat Recovery Exchanger (HRE) and Heat Pump (HP) have been investigated. Thermodynamic parameters including Coefficient of Performance (COP), universal and functional exergy efficiencies have been used to compare AHUs and to calculate the exergy destruction in AHU components at variable environment temperature −30 °C… + 10 °C. The results of this study show that using HRE the COP and exergy efficiencies are significantly better compared with AHU without HRE. Using the HRE of higher effectiveness, the thermodynamic indicators can be improved considerably. The study shows that AHUs equipped with HP with advanced control method and HRE are more advantageous compared with other investigated AHUs. The presented methodology could have practical application for evaluating of energy and exergy efficiency of AHUs at different reference temperatures when designing HVAC systems and implementing optimum control methods.