First Time In Open Literature Research Articles

On the cyclic deformation behavior of wire-based directed energy deposited Fe-Ni Invar alloy

Fe-basis alloys with Ni concentrations of approximately 36 wt.-% are widely used for components with high requirements on mechanical properties and dimensional accuracy. Due to the remarkably low coefficient of thermal expansion, these so-called Invar alloys provide for dimensional accuracy over a wide temperature range. Generally, additive manufacturing technologies have already been qualified for processing of Invar alloys in terms of maintaining mechanical as well as functional properties. However, the mechanical behavior under cyclic loading still is not comprehensively understood. Therefore, the present study focuses on the fatigue properties of the Fe-Ni36 Invar alloy manufactured by wire-based directed energy deposition (DED) employing either an electric arc (DED-Arc) or a laser beam (DED-LB) as energy source. Here, a wire-based DED-LB Invar condition is comprehensively studied for the first time in open literature. For initial assessment, specimens were analyzed using optical and scanning electron microscopy as well as computed tomography and tensile testing. Here, the DED-LB material is characterized by a heterogeneous grain size distribution, less pronounced crystallographic texture as well as increased tensile strength and ductility compared to the DED-Arc counterparts. Despite increased strength and ductility, the DED-LB Invar consistently shows inferior fatigue properties. This behavior is discussed based on microstructural heterogeneity, cyclic deformation response, process-induced porosity and the contribution of plastic strain. Furthermore, investigations on the thermal expansion behavior show that the DED Invar retains its outstanding thermal properties, respectively.

Proposing novel predictive group and atomic contribution models for hydrogen sulfide absorption by Deep Eutectic Solvents

Hydrogen sulfide (H2S) is one of the most dangerous impurities of natural gas which cause human and environmental issues. Thus, the main process of gas sweetening plants is H2S removal from natural gas. Amine solutions are the commonly used solvents for gas-sweetening processes in petroleum industries. However, amin solutions are not safe and cause many environmental issues especially in the post-process treatment of used amine. Thus, the issue of proposing green sustainable solvents for gas sweetening is vital for petroleum industries. Deep Eutectic Solvents (DESs) are the most recently introduced green solvents which have shown good capability for H2S absorption. Thus, DESs are one of the most possible candidates for green solvents to replace amine solutions. Experimental studies to choose suitable solvents is a tough challenge because working with H2S is very dangerous and requires expensive facilities. Therefore, an accurate and global thermodynamic model is necessary to predict the solubilities of H2S in DESs without the requirement of experimental data. This study for the first time in open literature, proposes two accurate and global thermodynamic models of group contribution (GC) and atomic contribution (AC) for predicting the H2S solubilities in various nature DESs. The largest and most updated data bank for H2S solubility in DESs was developed from open literature, including 415 solubility data of 37 different nature DESs. The proposed GC and AC models were developed according to the gathered data bank and their results were analyzed by statistical parameters. Both GC and AC models show normal behavior and promising results concerning experimental data by the calculated AARD% of 9.64, and 12.86, respectively.

Cryo-Assisted Nitrogen Treatment for the Fabrication of Nanoengineered, Mixed Transition Metal Oxide Anode from Inorganic Domestic Waste, for Lithium-Ion Batteries

A novel method for the fabrication of nanoengineered, mixed transition metal oxide anode active material is proposed based on implementing liquid nitrogen treatment during the chemical precipitation process, for the first time in open literature. Such interference in the precipitation is believed to change the surface energy of the nuclei leading to differentiation in the growth process. To exemplify this hypothesis with an environmentally friendly approach, kitchen scourer pads, an existing waste, are used as a starting material instead of using a mixture of primary quality metals’ salts. Therefore, in this study, firstly, an optimization is realized to leach the scouring pad with 100% efficiency. Then, by applying a conventional chemical precipitation to this leachate at pH 5.5, Sample 1-P is produced. Herein, innovatively liquid nitrogen treatment is carried out during the chemical precipitation to produce Sample 2-P. Lastly, these precipitates (Samples 1-P, 2-P) are calcinated in the air to form mixed transition metal oxide powders: Samples 1 and 2, respectively. Structural, chemical, and morphological characterizations are carried out to examine the effect of liquid nitrogen treatment on the powders’ properties. To discuss the effect of nitrogen treatment on the electrochemical performances of the anode active materials (Sample 1 and Sample 2), galvanostatic tests are realized. The results show that Sample 2 demonstrates a higher 1st discharge capacity (1352 mAh/g) and retains 62% of its performance after 200 cycles when 50 mA/g current load is applied. Moreover, this electrode delivers around 500 mAh/g at 1 A/g current load. The remarkable cycle performance of Sample 2 is believed to be related to the superior chemical, structural, and physical properties of the electrode active material.Graphical

On the fatigue behavior of a tool steel manufactured by powder bed based additive manufacturing—a comparison between electron- and laserbeam processed AISI H13

In recent years, additive manufacturing (AM) techniques have gained increased attention. The most common AM technologies to realize complex parts are powder bed-based fusion processes, especially electron beam powder bed fusion of metals (PBF-EB/M) and laser-based powder bed fusion of metals (PBF-LB/M). Focusing on industrial applications, cyclic loading scenarios and fatigue properties of components produced by such techniques came into focus of research. The present work deals with a comparison between microstructure, hardness, density and fatigue properties of a high-alloy tool steel AISI H13 (1.2344, X40CrMoV5-1) manufactured by PBF-EB/M and PBF-LB/M. The investigated specimens are characterized by a complex phase composition containing ferrite, perlite, bainite and martensite, eventually resulting in different hardness values depending on the used AM technology. Fatigue data for PBF-EB/M AISI H13 are reported for the first time in open literature. It is shown that the fatigue behavior is significantly influenced by the specimen density. Accordingly, parts with a high density are characterized by superior fatigue strength.

Extraction and Characterization of Cellulose Nanofibers From Yellow Thatching Grass (Hyparrhenia filipendula) Straws via Acid Hydrolysis

A variety of lignocellulosic raw materials have been previously reported for the production of cellulose and cellulose derivatives, but little research effort has been dedicated to producing cellulose from Hyparrhenia filipendula. In this study, cellulose nanofibers (CNFs) were extracted from Hyparrhenia filipendula waste straws via sulphuric acid hydrolysis. The straws were pretreated with a combination of physiochemical processes and hydrolyzed using sulphuric acid at three different concentrations (1 M, 3 M and 5.6 M) for 2 h at 80 °C. The properties of the CNFs was checked by Fourier Transform Infrared spectroscopy (FTIR) for surface chemistry, X-ray diffraction (XRD) for crystallinity, Scanning Electron microscopy and Transmission electron microscopy (TEM) for morphology. A high-performance liquid chromatograph (HPLC) was used to quantify the amount of biopolymers in the CNFs. The results show that CNFs, denoted as CNF 1, CNF 3, and CNF 5.6 for 1 M, 3 M, and 5.6 M sulphuric acid, respectively, were successfully extracted at the various concentrations of sulphuric acid. The cellulose content of CNF1, CNF3, and CNF5.6 determined by HPLC analysis were 85%, 77% and 78% respectively. Also, the hemicellulose content in CNF 1, CNF 3, and CNF 5.6 was 10%, 15%, and 12% respectively, showing a high carbohydrate content of the CNFs. The FTIR spectra confirm the absence of characteristic peaks for lignin in the CNFs. The XRD analysis reveals presence of characteristic cellulose Iβ peaks at 2θ of 18°, 26°, and 40° with the crystallinity of 78%, 74% and 73% for CNF1, CNF3 and CNF5.6, respectively. Moreover, SEM analysis shows the deposition of lignin polycondensate on the surface of CNF 1, CNF 3, and CNF 5.6 while the bleached sample has a smooth and glossy appearance. The TEM analysis shows long unbranched nano-sized fibers for CNF 1 and shorter fibrous network of fibers for CNF 3, and CNF 5.6. The average diameter of the fibers, measured with ImageJ software is 40 nm for CNF 1, 57 nm for CNF 3, and 92 nm for CNF 5.6. CNFs were successfully produced from Hyparrhenia filipendula and reported for the first time in open literature. In view of the structure and properties of the produced CNFs, they are a potential material for value-added applications such as polymer matrices, films, and membranes, thus enabling efficient utilization of agricultural waste.

LiFi through Reconfigurable Intelligent Surfaces: A New Frontier for 6G?

Light fidelity (LiFi), which is based on visible-light communications (VLC), is celebrated as a cutting-edge technological paradigm that is envisioned to be an indispensable part of 6G systems. Nonetheless, LiFi performance is subject to efficiently overcoming line-of-sight (LoS) blockage, whose adverse effect on the reliability of wireless reception becomes even more pronounced in highly dynamic environments, such as vehicular applications. Meanwhile, reconfigurable intelligent surfaces (RISs) have recently emerged as a revolutionary concept that transforms the physical propagation environment into a fully controllable and customizable space using a low-cost, low-power approach. We anticipate that the integration of RISs into LiFi-enabled networks will not only support blockage mitigation but will also provision complex interactions among network entities, and is hence manifested as a promising platform that enables a plethora of technological trends and new applications. In this article, for the first time in open literature, we set the scene for a holistic overview of RIS-assisted LiFi systems. Specifically, we explore the underlying RIS architecture from the perspective of physics and present a forward-looking vision that outlines potential operational elements supported by RIS-enabled transceivers and environments. Finally, we highlight major associated challenges and offer a look ahead toward promising future directions.

Comprehensive modelling of rotary desiccant wheel with different multiple regression and machine learning methods for balanced flow

In this paper, several alternative models were developed with multiple linear regression and machine learning algorithms to determine the output states of silica gel desiccant wheels for balanced flow. The decision tree method was used for this purpose for the first time in open literature. All the models developed include six input parameters and a wider range than those available in the literature. Predictions from the models were compared with the master dataset used to derive the models, each of the five sub-datasets that make up the master dataset and with data available in the literature. It was determined that the most suitable models are those coded as multiple linear regression-IV (MLR-IV), multilayer perceptron regressor-III (MLPR-III) and decision tree-VII (DT-VII), and DT-VII is the best among them. The determination coefficient and root mean square error for temperature were found to be 0.9894 and 0.8743 °C for MLR-IV, 0.9817 and 1.1526 °C for MLPR-III, 0.9986 and 0.3295 °C for DT-VII, respectively. The corresponding values for humidity ratio were 0.9912 and 0.3701 g kg−1 for MLR-IV, 0.9885 and 0.4227 g kg−1 for MLPR-III, 0.9994 and 0.0995 g kg−1 for DT-VII, respectively. The results obtained revealed that the proposed models can be used safely in preliminary design, simulation and dynamic energy analysis of systems with desiccant wheels.

Green synthesis of carbon based biosensor materials from algal biomass for the sensitive detection of vardenafil

In this study, a novel carbon electrode material for improved electrochemical sensing of vardenafil (VRF) as a model drug active substance was prepared by two cycled hydrothermal carbonization (HTC) of algae-based biomass for the first time in open literature. In order to increase the electrical conductivity more, multi-walled carbon nanotube (MWCNT) was used as a catalyst during the second cycle of HTC. The surface morphology and chemical structure of the synthesized carbonaceous materials were investigated by using different techniques. The voltammetric behaviour of VRF drug was investigated on glassy carbon electrode (GCE) modified by algae based carbon electrode material. MWCNT catalyzed carbon material obtained from second cycle of HTC treatment exhibited more sensitive, reproducible and low oxidation potential comparing to bare GCE in the presence of VRF due to the increased degree of graphitization. At the optimum conditions, differential pulse voltamograms (DPV) method with MWCNT catalyzed carbon material exhibited high sensitivity with the detection limits of 96.3 pM at pH 1.0 H2SO4 solution, 60.6 nM at serum and 46.7 nM at urine samples. Finally, the proposed sensor was successfully applied in tablet formulation, human serum and human urine samples.

Experimental measurement and prediction of carbon dioxide clathrate hydrate phase boundary in presence of ethanol + sodium chloride, potassium chloride, magnesium chloride and calcium chloride aqueous solution

The dissociation condition of clathrate hydrate of carbon dioxide in aqueous solutions of ethanol + NaCl, KCl, MgCl2 and CaCl2 are measured in the temperature range of (259.4–274.7) K and pressures up to 3.7 MPa. Isochoric pressure-search method is used for all measurements. In addition for the first time in open literature a machine learning algorithm model based on artificial neural network is developed to predict equilibrium temperatures. Absolute relative deviation (ARD) and correlation coefficient (R2) for trained neural network are 0.0305 and 0.9994, respectively.

On the rig dock tuning of large sail yachts

Dock tuning is a crucial stage in the rig service life and in the sailing management. Such operation is necessary for safety and structural stability reasons. The applied pretension has the purpose to increase the stiffness of the whole rig, reducing large displacements caused by aerodynamic and inertial loads. Furthermore, since the rig is aimed at supporting sails, its deformation significantly affects aerodynamic performances, so that dock tuning has also a relevant impact on the propulsion, especially in racing. However, the complexity of the problem and the peculiarities of each different system are the causes of the lack of specific dock tuning procedures in rules and guidelines of Classification societies.The present work, developed in collaboration with the Italian shipyard Perini Navi S.p.A., consists in the validation of a dock tuning numerical procedure adopting a Finite Element Method (FEM) applied to a 67 m long mast. A detailed comparison with real-scale experimental results has been carried out, highlighting the importance of a reliable modelling to accurately predict the non-linear behaviour of the structure. Technical guidelines for dock tuning simulation of large rigs are also provided for the first time in open literature, to the best of the authors’ knowledge.

A Brief History of Chemical Reactor and Reaction Technology

AbstractThe term “chemical reactor” appears for the first time in open literature at the end of First World War, while in Germany the term “reaction technology” was coined in the 1950s, although chemical reactions and processes have been known for thousands of years. In the early days, reactors were furnaces and pots, which specialized further over the centuries. With the Industrial Revolution many reactor types were already known, and industrialization brought an enormous innovation thrust in the field of products as well as technologies. The diversity of reactors today is almost uncomprehensive and so efforts to standardize apparatus are understandable.

A comparative study of frictional response of shed snakeskin and human skin

Skin in biological systems, including humans, perform several synchronized tasks (mechanical, protective, tactile, sensory, etc.). Tribological function is among skin tasks and may determine the survivability of many species. Cross comparison of tribological functional traits of skin of different species, albeit interesting, is rarely encountered, if at all exists, in tribology literature. One interesting example is that of snake and human skins. This skin pair was the subject of many studies for transdermal drug delivery. Results in that context concluded that snakeskin is highly compatible with human skin despite apparent differences in surface structure and topology. The reported compatibility raises curious question of whether there exists frictional or tribological compatibility between the two skins and if so, under what conditions, and which context. In this work, we report, for the first time in open literature, results of a comprehensive comparative investigation of shed snakeskin and human skin with respect to tribological behaviour. To this end, we compared the frictional response of shed skin obtained from P. regius and human skin from different anatomical sites, gender, and age. The results imply that, in essence, the mechanisms governing the friction response of human skin are common to snake skin despite difference in chemical composition and apparent surface structure. In particular, both skin types display sensitivity to hysteresis and adhesive dissipation. Human skin, however, being more sensitive to hysteresis than snakeskin. One interesting finding of the study is that the ratio of the coefficients of friction for snake and human skin, when sliding on the same interface, depends on the reciprocal of their respective moduli of elasticity.

Humidity Effects on Experimental Compressor Performance—Corrected Conditions for Real Gases

The effects of humid air on the performance of a multistage research compressor and new methods of humidity accounting to ensure appropriate representation of performance parameters are investigated in this paper. Turbomachinery textbooks present methods of correcting speed and mass flow rate using perfect gas assumptions, but these methods can reduce the ability to achieve repeatable compressor performance when using unconditioned air in a climate where absolute humidity may vary. Instead, a new method is introduced, which models humid air as a real gas and circumvents the need for assumptions in the correction process. In the area of compressor research, the ability to measure small changes in performance parameters and ensure repeatable results is essential. Errors of more than 0.5% can result from using perfect gas assumptions to calculate corrected speed, which can lead to misrepresented performance parameters beyond the uncertainty of the measurements. Multiplicative correction factors based on analytical data are also introduced as an alternate method of applying the new real-gas method, and these correction factors are compared to those derived by previous authors applying ideal gas methods for humidity accounting. This is the first time in open literature that experimental results for a component of a gas turbine engine are presented comparing a humid air correction method with traditional correction methods.

Dehydration of reactive industrial mixtures by pervaporation: An innovative approach in acrylic esters processes

This work demonstrates for the first time in open literature the dehydration by pervaporation of reactive mixtures encountered in the synthesis of ethyl acrylate. These mixtures contained, together with water and ethanol, highly reactive monomers, i.e., acrylic acid and ethyl acrylate. Among commercially available membranes, the Pervap#1201 of Sulzer Chemtech and the Zeolite-T of Mitsui were identified as promising membranes. As Pervap#1201 clearly performed better, it was selected for detailed pervaporation investigations. The total permeation flux of Pervap#1201 varied from 0.05 to 1.2kgm−2h−1 and the water permeance varied from 360 to 1700 GPU depending on the mass fraction of water in the feed (0.02–0.15) and the operating temperature (65–95°C). Its separation factor (β) toward water was greater than 4000 and the selectivity (α) was greater than 200. Permeate is essentially composed of water (0.99 mass fraction), ethanol (<0.007), acrylic acid (0.002) and ethyl acrylate (0.001). The permeate fluxes were modeled using the solution–diffusion approach and the estimated values showed good agreement with experimental values. The chemical stability of the Pervap#1201 membrane was investigated using continuous pervaporation experiments. Importantly, the performance of Pervap#1201 was demonstrated to be very stable, even after six months of immersion in a reaction mixture. Considering the pervaporation performances and the membrane stability in the presence of acrylic derivatives, the use of the Pervap#1201 membrane in the coupling reaction–esterification of ethyl acrylate appears to be very promising for industrial application.

Optimization of Elastic Supports for Laminated Composite Plates

The fundamental frequency of a plate can be raised by placing appropriate number of rigid supports at various optimal locations along the nodal lines of vibration modes, as previously shown by other researchers. Unlike previous works, however, the present study aims to determine the optimal locations and the corresponding minimum stiffness of elastic spring supports using a direct search optimization method, presuming that the nodal lines of vibration modes can be identified a priori. As examples of applications, the optimal locations and stiffness are determined for isotropic plates and laminated composite plates with various lamination schemes, results of the latter are presented for the first time in open literature. Although only plates with regular geometry are treated in this preliminary study, further extension to plates with irregular geometry and other boundary conditions is being carried out.

Convergence and exact solutions of spline finite strip method using unitary transformation approach

The spline finite strip method (FSM) is one of the most popular numerical methods for analyzing prismatic structures. Efficacy and convergence of the method have been demonstrated in previous studies by comparing only numerical results with analytical results of some benchmark problems. To date, no exact solutions of the method or its explicit forms of error terms have been derived to show its convergence analytically. As such, in this paper, the mathematical exact solutions of spline finite strips in the plate analysis are derived using a unitary transformation approach (abbreviated as the U-transformation method herein). These exact solutions are presented for the first time in open literature. Unlike the conventional spline FSM which involves assembly of the global matrix equation and its numerical solution, the U-transformation method decouples the global matrix equation into the one involving only two unknowns, thus rendering the exact solutions of the spline finite strip to be derived explicitly. By taking Taylor’s series expansion of the exact solution, error terms and convergence rates are also derived explicitly and compared directly with other numerical methods. In this regard, the spline FSM converges at the same rate as a non-conforming finite element, yet involving a smaller number of unknowns compared to the latter. The convergence rate is also found superior to the conventional finite difference method.

Field test investigation of a double-stage coupled heat pumps heating system for cold regions

This paper reports a double-stage coupled heat pumps (DSCHP) heating system, which couples air source heat pump (ASHP) and water source heat pump (WSHP) together. The system is presented for the first time in open literature with the objective to improve the working condition and heating performance of the ASHP under cold environment. A practical project in Beijing firstly installed this system and field test has been performed for one month. The test results indicate that the DSCHP system can be smoothly and efficiently used for heating in cold regions. Compared with the traditional ASHP heating system, the operating characteristics of the DSCHP heating system are greatly improved, demonstrating that the system can offer considerable application potential in cold regions.

Thermoeconomic analysis of mixed gas–steam cycles

In this paper the direct thermoeconomic analysis approach developed by the authors [ASME Paper 95-CTP-38; ASME Cogen Turbo Power Conference, Wien, 23/25 August, 1995] is applied to the assessment of the thermoeconomic performance of mixed gas–steam cycles such as the steam injected cycle (steam injected gas turbine, STIG), regenerated water injected (RWI) cycle, and humid air turbine (HAT) or evaporative cycle. All the simulations were carried using the thermo-economic modular program (TEMP) code developed at the University of Genoa [ASME Trans., J. Engng. Gas Turbine Power 119 (1997) 885; Thermo-economic and environmental optimisation of energy systems, Tesi di Dottorato, Università di Genova (DIMSET), 1997] and carefully tested here, mainly for the HAT cycle and saturator, using the experimental data provided by the HAT pilot-plant operating at the Lund University, Sweden [Theoretical and experimental evaluation of the EvGT-process, Thesis for Degree of Licentiate in Engineering, Lund Institute of Technology, Sweden, 1999; Evaporative cycles – in theory and in practice, Doctoral Thesis, Lund Institute of Technology, Sweden, 2000]. Three different mixed cycles (STIG, RWI, and HAT) are analysed in detail together with an additional fourth layout proposed by the authors [Thermoeconomic analysis of STIG, RWI and HAT cycles with carbon dioxide (CO 2) emissions penalty, Tesi di laurea, Università di Genova (DIMSET), 2000], named HAWIT, humid air water injection turbine, that appears to be the most attractive solution. The thermoeconomic results of mixed cycles are presented here for the first time in open literature. These results are compared to the data of a conventional two-pressure level combined cycle considered as representative of the state of the art of high efficiency conversion systems. A new representation proposed by the authors [ASME Trans., J. Engng. Gas Turbine Power 122 (2000)], such as cost of electricity versus cycle efficiency or internal rate of return versus electric efficiency, is used to demonstrate the main features of these types of innovative energy plants.

TLCT and LDV measurements of heat transfer and fluid flow in a rotating sharp turning duct

Heat transfer measurements using a transient liquid crystal thermometry (TLCT) are presented to study the effect of rotation on the local heat transfer distributions around a sharp 180° turn of a two-pass smooth square duct for the first time in open literature. The duct has a dimensionless divider wall thickness of 0.25. Detailed local Nusselt number distributions on the leading and trailing walls are given for rotation numbers ranging from Ro=0 to 0.20 at a Reynolds number of 1.0×10 4. The results show informative spanwise variations of heat transfer enhancement or abatement resulting from rotation. A critical range of Ro is identified, below which the regional averaged Nusselt number ratios of the regions after the 180° sharp turn in a rotating two-pass cooling passage are rather insensitive to the rotation effect. Laser–Doppler velocimetry (LDV) measurements within the turn are further performed to explain the local heat transfer distributions. Under rotating conditions, the curvature induced symmetric Dean vortices in the turn for the stationary case change greatly and are dominated by a single vortex most of which impinges directly on the leading wall's outer part, resulting in a high heat transfer enhancement on the leading wall in the turn.

On robust two-pattern testing of one-dimensional CMOS iterative logic arrays

In this paper a graph model and a method to construct robust (for the first time in open literature) as well as non-robust two-pattern tests for one-dimensional iterative logic arrays (ILAs) are presented. Exploring the graph structure we can find two-pattern tests that can be applied with a constant or linear number of test vectors to all the ILA cells. Such tests are subsequently characterized as robust or non-robust two-pattern tests.