Genetic tool monitor (GTM) for micro-end-milling operations

Almost all existing tool condition monitoring methods require either the critical parameters of models which are experimentally found or the self-learning algorithms that are trained with existing data. Genetic Tool Monitor (GTM) is proposed to identify the problems by using an analytical model for micro-end-milling operations and genetic algorithm. The current version of the GTM is capable to monitor the micro-end-milling operations without any previous experience and is able to estimate symmetrical wear and local damages at the cutting edges of a tool. Genetic algorithms (GA) are found as a promising health monitoring tool if an expression exists and the necessary computational time is allowable in that particular application. GTM generates meaningful information about the ongoing operation and allows the establishment of rules based on the operators' experience.     

Transient response in magnetocaloric regeneration

We report on the first experimental demonstration of the details of the transient response in the four sequential processes of active magnetic regenerative refrigeration: magnetization, warm blow, demagnetization, and cold blow. The experimental results display the details of the gradual temperature divergence due to regeneration. The temperature change of the stationary solid bed is due to the magnetocaloric effect in a periodic field. The theory for the active magnetic regenerative refrigeration is applied to the transient processes in magnetocaloric regeneration. A time and spatial dependent model of temperature profile of the magnetization and demagnetization with thermal wave regenerative processes is developed.     

Molecular-Level Structure?Property Relationships in Biogenic Calcium Carbonates: The Unique Insights of Solid-State NMR Spectroscopy

The biomineralization process produces materials with exceptional microscopic, morphologic, and mechanical qualities, which are finely tuned for specific functionality. This control of the properties is obtained through interactions with bioorganic and inorganic molecules that regulate the formation and/or become incorporated into the final biomineral. Although the interfacial regions comprise a minute fraction of the mineral, they are of paramount importance. Modern solid-state NMR spectroscopy techniques enable to focus on these biomineral interfaces and defects, and to determine their molecular-level structures; a task that is barely attainable by other methods. Biogenic calcium carbonates are highly abundant and extensively investigated. Currently, only a limited number of such systems have been studied by solid-state NMR spectroscopy. Reviewing these herein, we demonstrate the power and adequacy of NMR spectroscopy to probe biogenic systems and highlight many questions that remain open and can benefit from further application of advanced NMR spectroscopy techniques.     

SLIDING‐MODE LINEARIZATION TORQUE CONTROL OF AN INDUCTION MOTOR

This paper proposes a sliding‐mode linearization torque control (SMLTC) for an induction motor (IM). An ideal feedback linearization torque control method is firstly adopted in order to decouple the torque and flux amplitude of the IM. However, the system parameters are uncertainties, which will influence the control performance of the IM in practical applications. Hence, to increase the robustness of the IM drive for high‐ performance applications, this SMLTC aims to improve the immunity of those uncertainties. We modify the flux observer of Benchaib and Edwards [15] by means of the adaptive sliding‐mode method. This not only eliminates the estimation of the uncertainty bounds, but also improves the performance of sliding control. In addition, a practical application of the proposed SMLTC, with a model reference adaptive control (MRAC) scheme incorporated as the inner and outer loop controller used for position control, is also presented. Some experiments are presented to verify the control theory and demonstrate the robustness and effectiveness of the proposed SMLTC.     

Publication patterns’ changes due to the COVID-19 pandemic: a longitudinal and short-term scientometric analysis

Scientometrics - In recent months the COVID-19 (also known as SARS-CoV-2 and Coronavirus) pandemic has spread throughout the world. In parallel, extensive scholarly research regarding various...     

Enhancement of corrosion protection effect of poly(styrene‐co‐acrylonitrile) by the incorporation of nanolayers of montmorillonite clay into copolymer matrix

A series of polymer–clay nanocomposite (PCN) materials that consisted of poly(styrene‐co‐acrylonitrile) (PSAN) and layered montmorillonite (MMT) clay were successfully prepared by effectively dispersing the inorganic nanolayers of MMT clay into the organic PSAN matrix by a conventional in situ thermal polymerization. First of all, organic styrene and AN monomers at a specific feeding ratio were simultaneously intercalated into the interlayer regions of organophilic clay hosts and followed by a typical free‐radical polymerization with benzyl peroxide as initiator. The as‐synthesized PCN materials were subsequently characterized by FTIR spectroscopy, wide‐angle powder X‐ray diffraction, and transmission electron microscopy. The as‐prepared PCN materials, in the form of coatings, incorporated with low clay loading (e.g., 1 wt %) on cold‐rolled steel, were found to be much superior in corrosion protection over those of bulk PSAN based on a series of standard electrochemical measurements of corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. Molecular weights of PSAN extracted from PCN materials and bulk PSAN were determined by gel permeation chromatography with THF as eluant. Effects of the material composition on the molecular barrier and thermal stability of PSAN along with PCN materials, in the form of both membrane and fine powder, were also studied by molecular permeability analysis, differential scanning calorimetry, and thermogravimetric analysis, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2269–2277, 2004     

Comparative studies of the properties of poly(methyl methacrylate)–clay nanocomposite materials prepared by in situ emulsion polymerization and solution dispersion

A series of polymer–clay nanocomposite (PCN) materials consisting of organic poly(methyl methacrylate) (PMMA) and inorganic montmorillonite (MMT) clay platelets were prepared successfully by the effective dispersion of nanolayers of the MMT clay in the PMMA framework through both in situ emulsion polymerization and solution dispersion. The as‐prepared PCN materials obtained with both approaches were subsequently characterized with wide‐angle powder X‐ray diffraction and transmission electron microscopy. For a comparison of the anticorrosion performance, a PCN material (e.g., 3 wt % clay loading) prepared by in situ emulsion polymerization, showing better dispersion of the clay platelets in the polymer matrix, exhibited better corrosion protection in the form of a coating on a cold‐rolled steel coupon than that prepared by solution dispersion, which showed a poor dispersion of the clay nanolayers according to a series of electrochemical corrosion measurements. Comparative studies of the optical clarity, molecular barrier properties, and thermal stability of samples prepared in both ways, as membranes and fine powders, were also performed with ultraviolet–visible transmission spectroscopy, molecular permeability analysis, thermogravimetric analysis, and differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1936–1946, 2004     

Genetically Encoding Light-Responsive Protein-Polymers Using Translation Machinery for the Multi-Site Incorporation of Photo-Switchable Unnatural Amino Acids

A general and versatile technology to engineer light-responsive protein-based biomaterials can enable the manipulation and interrogation of proteins, pathways, and cells, and it will assist the design of “smart” light-responsive biomaterials. This study reports the evolution of chromosomal aminoacyl-tRNA synthetases (aaRSs) for azobenzene-bearing unnatural amino acids (uAAs) with up to ≈40-fold increased protein production and improved fidelity, as compared with a previously described aaRS. The evolved translation systems enable efficient and accurate incorporation of up to 10 instances of the various light-responsive uAAs in elastin-like polypeptides (ELPs). Azobenzene-containing ELPs are capable of isothermal, reversible, light-mediated soluble-to-insoluble phase transition, with up to a 12  °C difference in the ELP transition temperature upon cis-to-trans azobenzene isomerization. Furthermore, the incorporation of azobenzene-uAAs in ELP diblock-copolymers enables the creation of light-responsive self-assembled nanostructures. Finally, light-responsive resilin-inspired polymers are also generated by multi-site azobenzene-incorporation. The translation machinery evolved in this study can be used for the multi-site incorporation of azobenzene moieties at the polypeptide level and constitute a universal methodology for the design of light-responsive proteins and additional families of protein-based biomaterials with customized and tunable light-responsive behavior.