For two processes of large importance, catalysis and biocatalysis, were reported zones without reactants, so called dead zone (DZ). They results from diffusional transport limitations, when apparent reaction order is between (-1..1). Formation of DZ reduces effectiveness of catalyst and influence packed bed reactor productivity. For simple reaction kinetic model, a DZ width inside a pellet can be calculated analytically solving appropriate differential mass balance model. However, generally the analytical solution is unknown and only with using numerical method the position of DZ can be established. The problem with DZ appearance belongs to problems with moving boundaries. Its solution requires application of special numerical procedure and relatively long CPU time. In this work it was proposed a simple, very fast numerical method for calculation of DZ position inside pellet. The method proposed combined with orthogonal collocation on finite elements can be applied for analysis of work of packed bed reactor.

Numerical optimization of the manufacturing process of hybrid lightweight struc- tures consisting of fiber-reinforced plastics (FRP) is of high importance. It can reduce the time to market and can also avoid the production of costly prototypes. To model the considered thermoforming process, the temperature dependent defor- mation mechanisms have to be characterized and modeled within a finite element framework. An industry-oriented approach based on the parameterization of a mate- rial model implemented in LS-DYNA is introduced. The accordingly parameterized material model for the FRP is eventually applied in the simulation of thermoforming processes to show the influence of process and material parameters on the forming behavior of the thermoplastic prepreg.

In this manuscript, a two-port semi-circular patch antenna with Koch curve fractals is presented as a suitable candidate for portable UWB communication systems. The proposed fractal array is engraved on a 1.57 mm thick FR-4 substrate with an overall array size of 30.5 × 47 × 1.64 mm3. The upper substrate layer consists of two microstrip-line fed semi-circular patches combined with two Koch curve fractals (optimized up to 2nd order of iteration) separated by a distance of λ/2. To mitigate the effect of mutual coupling between the radiating elements, the lower substrate layer consists of a reduced ground plane with a funnel-shaped decoupling structure. To achieve a high degree of isolation (S21/S12 ≤ -16.8 dB) between the ports of the proposed array, two rectangular and L-shaped slots (mirror images of each other) are etched from the upper surface of the reduced ground. The design and simulation of the proposed antenna array is implemented in CST MWS’18. The optimized fractal array covers the simulated frequency band from 4.395-10.184 GHz with a fractional bandwidth of 79.4 % (at a center frequency of 5.789 GHz) and provides a peak radiation efficiency of 88.8% (at 6.2 GHz frequency). The antenna diversity performance is analyzed in terms of envelope correlation coefficient (ECC ≤ 0.0021), diversity gain (DG ≥ 9.989), mean effective gain (MEG ≥ -3.7 dB), channel capacity loss (CCL ≤ 0.4 bits/s/Hz) and total active reflection coefficient (TARC ≤ -10 dB). The experimentally measured S-parameter results show a good match with the simulated ones.

Surface discharges occurring on a porcelain bushing under DC voltage not only causes an incipient fault condition but also can degrade the pertinent location once the surface deposition layer or the insulation material gets carbonized. Naturally, it becomes important to identify and analyze the surface discharges occurring on bushing. The current practice on analyzing surface discharges initiated under DC voltage employs partial discharge test methods that focuses on counting the PD events occurring over a time span. The method is sensitive but provides no information about the possible source of fault condition. In this context, a non-conventional, pattern based partial discharge analysis method on understanding the characteristics of electrical discharges occurring on the surface of a polluted bushing under DC voltage is studied. Initially, a half-wave bridge rectifier unit that produces an uncontrolled DC voltage is selected and employed. Later, the surface of the polluted bushing is energized, and the signals initiated by the surface discharges occurring on the surface contaminated bushing are recorded. Instead of counting the PD events, the pattern manifested by the surface discharges is correlated to the AC voltage input of the rectifier. Once this is accomplished, the pertinent findings are validated on an actual bushing installed in an electrostatic precipitator unit that is applied for cleaning producer gas of a biomass gasification plant.

Low-field nuclear magnetic resonance (NMR) relaxometry is an attractive approach for point-of-care testing medical diagnosis, industrial food science, and in situ oil-gas exploration. However, one of the problems is the inherently long relaxation time of the (liquid) sample (and hence low signal-to-noise ratio) which causes unnecessarily long repetition time. In this work, a new methodology is presented for a rapid and accurate object classification using NMR relaxometry with the aid of machine learning techniques. It is demonstrated that the sensitivity and specificity of the classification are substantially improved with a higher order of (pseudo)-dimensionality (e.g., 2D or multidimensional). This new methodology (the so-called Clustering NMR) may be extremely useful for rapid and accurate object classification (in less than a minute) using the low-field NMR.

In this work, a 0.9-2.4 GHz, 25 Watt output power, radio frequency (RF) power amplifier based on Class-E switchmode topology has been analyzed. A load-pull simulations method is used to optimize the power performance in the operating band. To design input and output matching networks an optimized low pass filter network was used. Simulated results of the power amplifier (PA) demonstrate wideband behavior which covers a 0.9 GHz to 2.4 GHz band with an efficiency of 32-78%, and an output power of 25 W (44 dBm), and an average gain of 20 dB. The designed PA provides attractive features associated with a wider band, high gain, and efficiency, which makes it a proper candidate for the mobile transmitter and cellular infrastructure applications.

We present comprehensive measurements of the evaporation behaviour, E, of a thinning film during a hydrodynamic-evaporative spincoating experiment. E, ω (rotational speed), and \nu (viscosity) are the main control parameters of the process. The evolution of the entire film thinning process can be described theoretically quite well based on the bulk value of \nu of the deposited liquid and with a process-specific (constant) E. The weighing in values of \nu are easily accessible (calculations, literature values, simple measurements). E is specific for the experimental conditions and values cannot be found in literature. There is also no generally accepted strategy to calculate E in advance. We analyzed our experimental results in view of a theoretical prediction for E, which was presented already some time ago by Bornside, Macosco, and Scriven, but never tested experimentally. We find good agreement between theory and experiment for many solvents and different! Accordingly, this approach permits in advance the calculation of the evolution of the entire hydrodynamic-evaporative film thinning in a spincoating process. In addition, we present a general formula, which allows in the case of spincoating mixtures of volatile solvents and nonvolatile solutes the prediction of the final solute deposit based on literature data only.

The ambitious Algerian program for diversification of electric energy sources is targeting 22 000 MWe from the renewable energy to the horizon of 2030. This study is a thermo-economic assessment of an integrated solar combined cycle system installed in the Saharan region, which during the nights or cloudy days works as a conventional combined cycle and does not need storage or back-up systems. The obtained results show, in one side that the solar electricity ratio may reach about 17 % and the global thermal efficiency up to 63 %, leading to lower fuel consumption and carbon emission. In the other side, the economic assessment depicts that the levelized cost of energy may reach a value of 0.0222 $/kWh which is about 28 % higher than CC plants. By considering the environment this latter is even more and may reach about 0.0272 $/kWh, but the annual solar contribution, relatively to that installation site, allows about 18.45 million $ of fuel saving and avoidance of 0.89 million ton of CO2 emission over 30 years of operation. operation. 

A novel approach towards developing a micro-bubble detection technology based on using a PZT transducer to induce an acoustic resonance state within the system under investigation is here presented. The concept, originally proof-of-concept tested in a cylindrical acoustic resonant chamber, has proven to be able to detect single microbubbles with diameters in the range of 390 to 600 µm in a swine thigh, with either saline solution or sheep blood as the medium in the bubble guide. It has shown to be extremely adaptable, capable of accommodating industrial pipes as well as biological specimens, resilient and extremely energy efficient, able to detect micro-bubbles with as little as 0.8 mW and potentially less.

This paper describes an in-depth methodical approach to the development of efficient high frequency (HF) antennas for usage in radio frequency identification (RFID) systems operating at 13.56MHz. It presents brief theory relevant to RFID communication and sets up a framework within which features and requirements of antennas are linked to key design parameters such as antenna form-factor and size; RF power level, materials and communication protocol. Tuning circuits necessary to adjust the resonance and power matching characteristics of antennas for good transponder interrogation and response recovery are discussed. To validate the approaches outlined, a complete step-wise antenna design and measurement described. Common practical problems that are often encountered in such design processes are also commented on.

We present a novel radar signal processing technique to identify the presence or absence of a living body in a vehicle using a mm-wave frequency-modulated continuous-wave radar. Unlike traditional detection methods which are mostly based on constant false alarm rate (CFAR), our proposed method extracts and monitors the consistent Doppler effect of received signals from the radar antenna resulting from the consistent breathing of living bodies over time. The proposed method works in all types of cars without the need for threshold definition for tracking as well as no need for training. Hence, the algorithm is more robust, accurate and fast. We assess our proposed signal processing with two phantoms mimicking the breathing of children and with adults in the vehicle in various conditions. The system has been proven to be robust in extensive studies over the course of multiple months.

As digitilisation is being applied in redefining products and business models world-wide, evidence abound in the construction industry as a sector that is slow to its adoption. While digitilisation tools have been applied in modifying processes/procedures in the global North; a larger percentage of the sector in the global South is yet to be disrupted. For indigenous firms to join the rapid transformation wheel, this study reviews the interrelationship between digitilisation and building information modeling. The study objectives are to examine the prevalence of cultural and strategic capability, evaluate the relationship between cultural orientation and strategic capability as well as predict a model of building information adoption from culture and strategy. The study population was drawn from the list of construction firms registered with the Lagos State Tender board, list of registered construction firms from the Institute and specific listed firms on the internet. Factor Analysis, Correlation and Regression were the adopted statistical tools. The results revealed production; task and goal attainment; information/communication technology; workforce; innovation, learning and knowledge management as well as conflict and dispute resolution as the prevalent cultural orientations. The availability of resources to communicate, interact and collaborate digitally and leadership capability to organise and coordinate digitally are the top two strategic capabilities. Consequently, 3 out of every 5 firms have moderate awareness on BIM implementation. It was concluded that the level of agreement on the adoption of the culture and the strategy did not reflect on the level of BIM adoption model. Since the results revealed that the existing orientation and strategy contribute about a tenth of BIM adoption model; the firms’ leadership need cultural re-orientation from the client angle and from business environment. On strategy, the firms need support from institutions/government on policies that will cushion the effect of the provision of resources for transformation.

A bendable UHF RFID tag antenna using non-uniform meandered lines for retail garments in the textile industry is presented. Based on an earlier UHF RFID tag antenna using nonuniform meandered lines, the proposed tag is fully bendable and aimed to be embedded in retail garments for long-life cycles. As a result, a relatively low cost, wide band, compactness and good conjugate matching with good dipole-like read range is presented. Results showed an antenna with a wide bandwidth of 900MHz and a long read range of 10.1m making the UHF RFID tag antenna using non-uniform meandered lines a potential candidate for retail garments in bendable applications of the textile industry. Simulations are corroborated by measurements and are in fairly agreement.

This work focused on the chemical synthesis and characterization of palm kernel oil (PKO) for bio-lubricant production using transesterification of palm kernel methyl ester (PKME) with trimethylolpropane (TMP) and epoxidation-esterification methods. The PKO was extracted using solvent extraction method. The physicochemical characteristics of the PKO and produced bio-lubricant samples were determined using standard methods. Fourier Transform Infrared (FTIR) spectrometry and Gas Chromatographic analyses, were respectively, used to determine the predominant functional groups and fatty acids of PKO and the produced bio-lubricant samples. At 55 °C, 150 min and 0.5 mm particle size, kernel oil yield was 49.82 % (by weight). The viscosities at 40 °C, 100 °C, viscosity index, pour and flash points of the bio-lubricants produced by transesterification of TMP (PKBLT) and epoxidation-esterification (PKBLE) methods, were [42.53 cSt, 10.65 cSt, 139, - 11 °C, 235 °C] and [44.69 cSt, 11.42 cSt, 132, - 12 °C, 240 °C], respectively. Time, mole ratio and temperature effects were the main factors that significantly influenced the transesterification and epoxidation processes. The obtained physicochemical properties of PKBLE and PKBLT samples showed conformity with ISO VG 32 standard, hence, their possible application as bio-lubricant basestock.

The out-of-plane displacement (OPD) of a circular dielectric elastomer actuator (DEA) membrane has been explored in recent years for a variety of important applications. Circular DEAs consist of an elastomer membrane that is prestretched to a rigid frame and coated with compliant electrodes. Such a simple configuration has found many interesting applications such as in, pumps, pulse tracking, hopping search and rescue robots, dielectric elastomer (DE) generators for renewable energy harvesting, linear actuators, and many others. Here, we present an easy-to-follow implementation of the OPD equations for circular DEAs via a detailed numerical solution using the shooting method (SM) on a system of differential algebraic equations (DAE), based on previous theoretical work. The SM numerical solution to the system of DAEs is applied to a practical range of values based on the reported literature. Analysis of the results and comparison against other studies are provided. The current work provides a go-to framework for implementation in further research and development.

In the power distribution network, real power loss and voltage profile management are critical issues. By providing active and reactive power support, both of these issues can be managed. This paper utilized the Meta heuristic-based method for the optimal size and placement of distributed generation (DG) and capacitor (QG) sources for loss reduction by incorporating network current carrying capacity constraint in the optimization problem. The overall problem is optimized using an upgraded method of the fitness assignment and solution chasing based on the aggregate approach called Multi-objective Whale Optimization Algorithm (MWOA). Wind and solar photovoltaic sources are utilized as the distributed generation with their probabilistic outputs. The developed method is tested using two feeders of practical Bahir Dar Distribution Network, Ethiopia. The results of loss minimization and voltage profile management with MWOA are compared with multi-objective particle swam optimization (MPSO) with an equal number of iteration to show the superiority of the developed method.

This study aims to investigate the effect of the processing parameters in plasma electrolytic oxidation (PEO) on the corrosion resistance of magnesium alloy type AZ91. The PEO coatings were prepared on the samples using alkaline-based electrolyte. Both unipolar and bipolar, different frequencies and duty cycles were applied. Corrosion tests, using potentiodynamic polarisation (PDP), linear and cyclic, and electrochemical impedance spectroscopy (EIS) techniques, were applied on the as-received and PEO coated samples. Scanning electron microscopy was used to investigate the surface morphology, e.g. micropores, as well as to measure the thickness of the coated layer with changing the processing parameters. The results show that the size of micropores is interrelated to the duty cycle percentage and current polarities, as the higher frequency causes thinner coating layers, with fewer micropores, consequently higher corrosion resistance. In addition, increasing the duty cycle, a denser and more compact coating was obtained. The XRD results showed missing peak of the α-Mg phase in a PEO coated sample using Bipolar, the highest frequency (1666 Hz) and the highest duty cycle (66.6%). The mils per year calculations showed that the PEO coated have lower corrosion rate by at least 8 times than the as-received alloy.

The Q/V band communication systems open new avenues for next generation of High Throughput Satellite (HTS) systems. More specifically, they are attractive due to their high bandwidth for user and gateway links. Having a wide bandwidth at Q/V band makes it permissible to offload the links between the satellite and its earth station hubs (gateway) from the Ka band to the Q/V band. This enables additional bandwidth available for HTS feeder links and user links of specific market verticals, which in turn results in reduction of cost per bit. In this paper, we are going to discuss different aspects of an In-Flight Connectivity (IFC) scheme for HTS. Developing a wideband and multibeam antenna is an essential part of this proposed system, which is also going to be discussed in this paper.