Application Engineers Research Articles

Crystal orientation dependence of metal–insulator transition for VO2 microwires fabricated on TiO2(110) substrates with step and terrace structures

Vanadium dioxide (VO2) thin films exhibit a metal–insulator transition (MIT) with sensitivity to the lattice strain. Substrates with step and terrace structures are an attractive platform for growing high-quality thin films. Thus, a prominent lattice strain effect could be derived using VO2 thin films on these substrates. In this study, VO2/TiO2 microwires were fabricated following the thin film growth to investigate the microwire-direction dependence of the MIT property. The in-plane crystal orientation dependence of the MIT property was enhanced for VO2/TiO2 microwires with step and terrace structures, which is promising for strain engineering in device applications.

Review of Traction System, Energy Efficiency and Electrical Design of Automated Guided Vehicles in Automotive Industry

Automated guided vehicles (AGVs) have been part of every production plant because of the increasing demand for production speed, efficiency and production throughput. Therefore, an AGV is part of the automation system in production plants. In that sense, AGVs can be considered as programmable and configurable robots because every production has specific AGV performance requirements such as AGV speed, positioning accuracy, maximum load, maximum speed, and safety standards. In this study, comprehensive system parameters are studied to provide a guideline to researchers and application engineers working on AGVs. Regarding the traction system, energy efficiency solutions, failure risks of AGV motors, and electrical design issues are the dedicated sections in this paper. On a global scale, cyber security and climate change are also two critical parameters that should be considered for component specifications of every AGV. As a case study in automotive production plants, an AGV developed in Ford Otosan R&D Center is presented. To this end, this paper is intended to be a design guideline considering the relationship between the upper-level software interacting with the environment and lower-level electrical components exposed to mechanical load.

Facilitating catalytic activity of indium oxide in lithium-sulfur batteries by controlling oxygen vacancies

Defect engineering plays a key role in lithium-sulfur (Li-S) batteries due to the altering of electronic states caused by defects that provide a promising opportunity to realize high-efficiency surface catalysis. Oxygen vacancies (OVs), the common defects in metal oxides, are often used to immobilize and catalyze lithium polysulfides (LiPSs). However, little effort has been devoted to developing novel oxygen defects manufacturing strategies and controlling its concentration to obtain an ideal effect. Herein, defect-rich electrocatalysts composed of In2O3-x nanoparticles and carbon spheres (CS) for Li-S batteries are reported by hydrothermal composition. Both experiments and theoretical calculations indicate that an appropriate quantity of oxygen vacancies can enhance the chemical adsorption and catalytic ability of LiPSs. As expected, the In2O3-x@CS-0.6/rGO-based cell displays an outstanding rate performance of 872 mAh g−1 at 3 C and a low fading rate of 0.058% each cycle after 100 cycles at 0.2 C, as well as a favorable areal capacity of 6.98 mAh cm−2 under high sulfur mass loading of 6.81 mg cm−2. This work furnishes a newness strategy to the rational design of oxygen vacancies of metal oxides and boosts the development of defect engineering in electrochemical applications.

Bismuth Vacancy-Mediated Quantum Dot Precipitation to Trigger Efficient Piezocatalytic Activity of Bi2WO6 Nanosheets.

Point defects in piezoelectric semiconductors play a significant role in regulating the piezocatalytic performance. However, the role of metal vacancies in piezocatalysis has been less explored than that of oxygen vacancies. Herein, Bi2WO6 (BWO) nanosheets with tunable Bi defects were synthesized using an ion exchange method. High-resolution transmission electron microscopy directly revealed the existence of Bi vacancies in the lattice of BWO nanosheets and the precipitation of Bi quasiparticles. The BWO nanosheets with the highest concentration of Bi vacancies exhibited an excellent decomposition efficiency (7.83 × 10-2 min-1) over rhodamine B under ultrasound. The phenomenon is mainly attributed to the increased charge carrier concentration as a consequence of defect energy levels. In addition, the significant enhancement of light absorption capacity caused by the surface plasmon resonance effect of quasiparticles indicates that Bi ions escape from the lattice and combine with free electrons around BWO to form Bi quantum dots, which function as electron traps to facilitate the separation of charge carriers during the piezocatalytic process. This work systematically reveals the essential affiliation of metal vacancies and surface metal clusters in piezocatalysts and verifies the significance of vacancy engineering in piezocatalytic application.

Novel Methodology for Inflection Circle-Based Synthesis of Straight Line Crank Rocker Mechanism

Abstract Emerging fields like Compact Compliant Mechanisms have created newer/novel situations for application of straight line mechanisms. Many of these situations in Automation and Robotics are multidisciplinary in nature. Application Engineers from these domains are many times uninitiated in involved procedures of synthesis of mechanisms and related concepts of Path Curvature Theory. This paper proposes a predominantly graphical approach using properties of Inflection Circle (IC) to synthesize a crank rocker mechanism for tracing a coupler curve which includes the targeted straight line path. The generated approximate straight line path has acceptable deviation in length, orientation, and extent of approximate nature well within the permissible ranges. Generation of multiple choices for the link geometry is unique to this method. To ease the selection, a trained artificial neural network (ANN) is developed to indicate relative length of various options generated. Using studied unique properties of Inflection Circles a methodology for anticipating the orientation of the straight path vis-à-vis the targeted path is also included. Two straight line paths are targeted for two different crank rockers. Compared with the existing practice of selecting the mechanism with some compromise due to inherent granularity of the data in Atlases, proposed methodology helps in indicating the possibility of completing the dimensional synthesis. The developed solution is well within the design specifications and is without a compromise.

Therapeutic enzyme engineering using a generative neural network

Enhancing the potency of mRNA therapeutics is an important objective for treating rare diseases, since it may enable lower and less-frequent dosing. Enzyme engineering can increase potency of mRNA therapeutics by improving the expression, half-life, and catalytic efficiency of the mRNA-encoded enzymes. However, sequence space is incomprehensibly vast, and methods to map sequence to function (computationally or experimentally) are inaccurate or time-/labor-intensive. Here, we present a novel, broadly applicable engineering method that combines deep latent variable modelling of sequence co-evolution with automated protein library design and construction to rapidly identify metabolic enzyme variants that are both more thermally stable and more catalytically active. We apply this approach to improve the potency of ornithine transcarbamylase (OTC), a urea cycle enzyme for which loss of catalytic activity causes a rare but serious metabolic disease.

Significant influence of Cu content on the radiation shielding properties of Ge-Se-Te bulk glasses

Bulk metallic glasses have attracted significant attention from researchers and material engineers for several applications. In this paper, we study the influence of Cu content on the radiation shielding properties xCu-(20-x)Ge-40Se–40Te (0 < x ≤ 20 at.%) bulk glasses. These bulk glassy samples are designed by utilizing FLUKA Monte Carlo based on their densities and chemical compositions. For x- and gamma-rays shielding studies, the mass attenuation coefficients (μ/ρ) of the bulk glasses are obtained via photon beam transmission experiment performed based on FLUKA simulations. Furthermore, we evaluate the shielding characteristics of the involved glassy specimens against charged particles and neutrons beam. The obtained findings show that the trend of μ follows the pattern: CGST1 < CGST2 < CGST3 < CGST4 < CGST5 for x = 0, 5, 10, 15, and 20, respectively. However, this trend is more conspicuous in the photoelectric effect dominated energies due to the greater dependence of μpe on the Z of the glasses. The present glassy samples show superior photon absorption capacity, especially CSGT5 sample, as compared to conventional shielding materials. Therefore, they can be deployed for nuclear shielding applications in space and other radiation environments.

Cellular responses to nanoscale substrate topography of TiO2 nanotube arrays: cell morphology and adhesion.

Nanotopographical features can be beneficial in augmenting cell functions and increasing osteogenic potential. However, the relationships between surface topographies and biological responses are difficult to establish due to the difficulty in controlling the surface topographical features at a low-nanometre scale. Herein, we report the fabrication of well-defined controllable titanium dioxide (TiO2) nanotube arrays with a wide range of pore sizes, 30-175 nm in diameter, and use of the electrochemical anodization method to assess the effect of surface nanotopographies on cell morphology and adhesion. The results show that TiO2 nanotube arrays with pore sizes of 30 and 80 nm allowed for cell spreading of bone marrow-derived mesenchymal stem cells with increased cell area coverage. Additionally, cell adhesion was significantly enhanced by controlled nanotopographies of TiO2 nanotube arrays with 80 nm pore size. Our results demonstrate that surface modification at the nano-scale level with size tunability under controlled chemical/physical properties and culture conditions can greatly impact cell responses. These findings point to a new direction of material design for bone-tissue engineering in orthopaedic applications.

Spin engineering of triangulenes and application for nano nonlinear optical materials design.

The recently synthesized triangulenes with non-bonding edge states could have broad potential applications in magnetics, spintronics and electro-optics if they have appropriate electronic structure modulation. In the present work, strategies based on molecular orbital theory through heteroatom doping are proposed to redistribute, reduce or eliminate the spin of triangulenes for novel functional materials design, and the role of B, N, NBN, and BNB in such intended electronic structure manipulation is scrutinized. π-Extended triangulenes with tunable electronic properties could be potential nonlinear optical (NLO) materials with appropriate inhibition of their polyradical nature. The elimination of spin is achieved by B, N, NBN, and BNB doping with the intended geometric arrangement for enhanced polarity. Intended doping of BNB results in an optimal structure with large static first hyperpolarizability (〈β0〉) as well as strong Hyper-Rayleigh scattering (HRS) βHRS(-2ω; ω, ω) (ω = 1064.0 nm), TG7-BNB-ba with a large 〈β0〉 (18.85 × 10-30 esu per heavy atom) and βHRS (1.15 × 10-28 esu per heavy atom) much larger than that of a synthesized triangular molecule (1.12 × 10-30 esu of 〈β0〉 per heavy atom and 5.04 × 10-30 esu of βHRS per heavy atom). The strong second order NLO responses in the near-infrared and visible regions, particularly the strong sum frequency generation, make these B or (and) N doped triangulenes promising candidates for the fabrication of novel carbon-based optoelectronic devices and micro-NLO devices.

Substitution of natural clay by Moroccan solid mining wastes to manufacture fired bricks

The objective of this work is to assess the feasibility of using solid mining waste (SMW) belonging to the Moroccan mining industry as an alternative raw material to manufacturing fired bricks instead of natural clay (CN). The feasibility was evaluated through: i) conducting physico-chemical and mineralogical characterizations on SMW. ii) Evaluation of the effect of CN substitution by solid SMW on technical properties of fired bricks. iii) Quantify the influence of firing temperature on physical, mechanical properties of fired bricks. For this reason, five mixtures containing 20, 40, 60, 80 and 100% of SMW as a substitute of CN were studied. The bricks specimens were fired at 900, 1000 and 1050 °C. The obtained results indicated that bricks containing up to 80% by weight of SMW and fired at 1000 and 1050 °C temperatures present the required technical properties that meet the applicable civil engineering and environmental standards. It can be concluded that these wastes can be successfully incorporated in the fired brick manufacturing industry which is in accordance with the concept of circular economy aimed to produce marketable products from the wastes.

PHYSICO-TRIBOLOGICAL ANND WEAR MECHANISM CHARACTERISTICS OF HYBRID REINFFORCED Al6063 MATRIX COMPOSITES

The development of engineering materials is continuously attracting attention from scientists and engineers for numerous engineering applications. The physical properties and wear mechanism of aluminium (Al 6063) matrix reinforced with silicon carbide (SiC) and palm kernel shell ash (PKSA) particulates at different weight ratios ranging from 0 to 10 wt.% with 2 wt.% intervals were investigated. The liquid route of double stir casting was employed in synthesizing the composites. The wear experiment was conducted using the Taber-type wear abrasion machine. The worn surfaces were examined using scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS), while the intermetallic phases were examined using the x-ray diffractometer (XRD). From the result, the increase in PKSA and SiC lowered and improved the density of the composites, respectively. The percentage porosity values (2 - 2.4%) obtained in this study were found to be within the acceptable limit of less than 4% for metal matrix composites castings. The mass loss and wear index increased owing to the rotating speed and applied load increase, resulting from the occurrence of mechanical mixing between the contacting surface of the sample disk and the machined disc. Adhesive and abrasive wear mechanisms were the major mechanisms observed in this study.

WIELAND C24000

Abstract Wieland C24000, also known as low brass, is an 80Cu-20Zn alloy. Low brass, named for its relatively low zinc content, is a choice of many design engineers for applications where strength and formability are required. Due to its higher zinc content (compared to red brass), low brass develops a beautiful antique brass color when chemically treated, making it ideal for many decorative or architectural applications. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on corrosion resistance as well as casting and heat treating. Filing Code: Cu-927. Producer or source: Wieland Rolled Products NA (formerly Olin Brass).

Bioremediation of Per- and Poly-Fluoroalkyl Substances (PFAS) by Synechocystis sp. PCC 6803: A Chassis for a Synthetic Biology Approach.

One of the main concerns in industrialized countries is represented by per- and poly-fluoroalkyl substances (PFAS), persistent contaminants hardly to be dealt with by conventional wastewater treatment processes. Phyco-remediation was proposed as a green alternative method to treat wastewater. Synechocystis sp. PCC6803 is a unicellular photosynthetic organism candidate for bioremediation approaches based on synthetic biology, as it is able to survive in a wide range of polluted waters. In this work, we assessed the possibility of applying Synechocystis in PFAS-enriched waters, which was never reported in the previous literature. Respirometry was applied to evaluate short-term toxicity of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which did not affect growth up to 0.5 and 4 mg L−1, respectively. Continuous and batch systems were used to assess the long-term effects, and no toxicity was highlighted for both compounds at quite high concentration (1 mg L−1). A partial removal was observed for PFOS and PFOA, (88% and 37%, with removal rates of about 0.15 and 0.36 mg L−1 d−1, respectively). Measurements in fractionated biomass suggested a role for Synechocystis in the sequestration of PFAS: PFOS is mainly internalized in the cell, while PFOA is somehow transformed by still unknown pathways. A preliminary bioinformatic search gave hints on transporters and enzymes possibly involved in such sequestration/transformation processes, opening the route to metabolic engineering in the perspective application of this cyanobacterium as a new phyco-remediation tool, based on synthetic biology.

Certificate complexity and symmetry of nested canalizing functions

Boolean nested canalizing functions (NCFs) have important applications in molecular regulatory networks, engineering and computer science. In this paper, we study their certificate complexity. For both Boolean values $b\in\{0,1\}$, we obtain a formula for $b$-certificate complexity and consequently, we develop a direct proof of the certificate complexity formula of an NCF. Symmetry is another interesting property of Boolean functions and we significantly simplify the proofs of some recent theorems about partial symmetry of NCFs. We also describe the algebraic normal form of $s$-symmetric NCFs. We obtain the general formula of the cardinality of the set of $n$-variable $s$-symmetric Boolean NCFs for $s=1,\dots,n$. In particular, we enumerate the strongly asymmetric Boolean NCFs.

Advanced parametric model for analysis of the influence of channel cross section dimensions and clamping pressure on current density distribution in PEMFC

The design of the flow field and the channel cross section of a bipolar plate as well as the intrusion effect of gas diffusion layers due to clamping pressure can significantly influence the performance of a fuel cell. The land and channel areas at a channel cross section can have different boundary conditions due to compression, intrusion of gas diffusion layers and transport phenomena. Todayapplication engineers are faced with the challenge of finding advantageous overall solutions from this plurality of multi-criteria parameters. In this thesis, a model approach is presented which combines a fully parametric analytical-empirical intrusion model with a 1D fuel cell model. This allows the calculation of current density distributions at the channel cross section, taking into account clamping pressure, channel parameters and operating conditions. Depending on the operating points considered, the results show that the maximum current densities occur in different areas of the channel cross section. In addition, with regard to the clamping pressure current density optima can be determined. Using this model approach, in an early development process application engineers will be able to compare hundreds of variants in a reasonable short time and thus determine advantageous fuel cell designs.

A Novel and Efficient Genome Editing Tool Assisted by CRISPR-Cas12a/Cpf1 for Pichia pastoris.

Pichia pastoris has been widely exploited for the heterologous expression of proteins in both industry and academia. Recently, it has been shown to be a potentially good chassis host for the production of high-value chemicals and pharmaceuticals. Effective synthetic biology tools for genetic engineering are essential for industrial and biotechnological research in this yeast. Here, we describe a novel and efficient genome editing method mediated by the CRISPR-Cpf1 system, which could facilitate the deletion of large DNA fragments and integration of multiplexed gene fragments. The CRISPR-Cpf1 system exhibited a precise and high editing efficiency for single-gene disruption (99 ± 0.8%), duplex genome editing (65 ± 2.5% to 80 ± 3%), and triplex genome editing (30 ± 2.5%). In addition, the deletion of large DNA fragments of 20kb and one-step integration of multiple genes were first achieved using the developed CRISPR-Cpf1 system. Taken together, this study provides an efficient and simple gene editing tool for P.pastoris. The novel multiloci gene integration method mediated by CRISPR-Cpf1 may accelerate the ability to engineer this methylotrophic yeast for metabolic engineering and genome evolution in both biotechnological and biomedical applications.

Streamlined CRISPR genome engineering in wild-type bacteria using SIBR-Cas.

CRISPR-Cas is a powerful tool for genome editing in bacteria. However, its efficacy is dependent on host factors (such as DNA repair pathways) and/or exogenous expression of recombinases. In this study, we mitigated these constraints by developing a simple and widely applicable genome engineering tool for bacteria which we termed SIBR-Cas (Self-splicing Intron-Based Riboswitch-Cas). SIBR-Cas was generated from a mutant library of the theophylline-dependent self-splicing T4 td intron that allows for tight and inducible control over CRISPR-Cas counter-selection. This control delays CRISPR-Cas counter-selection, granting more time for the editing event (e.g. by homologous recombination) to occur. Without the use of exogenous recombinases, SIBR-Cas was successfully applied to knock-out several genes in three wild-type bacteria species (Escherichia coli MG1655, Pseudomonas putida KT2440 and Flavobacterium IR1) with poor homologous recombination systems. Compared to other genome engineering tools, SIBR-Cas is simple, tightly regulated and widely applicable for most (non-model) bacteria. Furthermore, we propose that SIBR can have a wider application as a simple gene expression and gene regulation control mechanism for any gene or RNA of interest in bacteria.

Cascaded Voltage and Current Control for a Dual Active Bridge Converter with Current Filters

The paper describes the cascaded voltage and current control for a bidirectional DC/DC converter in Dual Active Bridge (DAB) topology. The typical DAB converter circuit was extended by additional current filters, which allow it to operate in application fields with high requirements on current ripples. The core concept of the presented solution is usage of the modified Single Phase Shift (SPS) modulation, which allows to compensate for the DC-bias current occurring in dynamic states and provides a settling time of half switching cycle during transients. Its features were utilized to build a simplified dynamic model of the converter. The linear Proportional-Integral (PI) controllers are used in both voltage and current control loops. Based on the developed dynamic models, the tuning rules for both controllers were derived. In both cases, a number of the tuned parameters were reduced from two to one (which can present a great practical value for application engineers). The proposed solutions are validated based on a laboratory prototype. An important part of the experiments was devoted to non-linear effects occurring near the current limitation boundary of the system. The paper ends with a brief discussion regarding the future research directions.

Aeration performance of high-head siphon-shaft spillways by CFD models

Siphon-shaft spillways are constituted by covering above a shaft spillway with a hood that creates siphonic pressure. This study focused on the aeration the flow through the aerator holes placed on the hood to prevent cavitational damage in high-head siphon-shaft spillways. Three-dimensional computational fluid dynamics (CFD) technique using finite-volume method to solve Reynolds-averaged Navier–Stokes (RANS) equations for the incompressible viscous and turbulent fluids motion was performed to analyze the full-scaled two-phase numerical models. The volume of fluid (VOF) scheme was used to simulate two-phase (water–air) flow, by defining the volume fraction for each of the fluids throughout the solution domain. The accuracy of the numerical model was tested using a procedure recommended by American Society of Mechanical Engineers (ASME) for CFD applications. The numerical results showed that the aeration is highly effective in reducing siphon sub-pressures and cavitation. The optimal relative aeration diameter of 0.45 provided sufficient air entrainment to protect from cavitation and did not decrease the discharge performance too much.

Adaptive Fixed-Time Neural Network Tracking Control of Nonlinear Interconnected Systems.

In this article, a novel adaptive fixed-time neural network tracking control scheme for nonlinear interconnected systems is proposed. An adaptive backstepping technique is used to address unknown system uncertainties in the fixed-time settings. Neural networks are used to identify the unknown uncertainties. The study shows that, under the proposed control scheme, each state in the system can converge into small regions near zero with fixed-time convergence time via Lyapunov stability analysis. Finally, the simulation example is presented to demonstrate the effectiveness of the proposed approach. A step-by-step procedure for engineers in industry process applications is proposed.