Collapse analysis of Al 6061 alloy conical shells with circular cutouts under axial loading: experiment and simulation

The current research is conducted to investigate the experimental and numerical study of crushing behavior and buckling modes of thin-walled truncated conical shells with or without cutouts and discontinuities under axial loading. In this regard, Instron 8802 servohydraulic machine is used to perform the experiments. Additionally, the buckling modes, derived from the axial collapse phenomenon, are simulated with Finite Element (FE) software. The force-displacement diagrams extracted numerically are compared with experimental results. Various factors, including maximum force, energy absorption, specific energy, and failure modes of each case, are also discussed. The results indicate that the increasing cutout cause a decrease in the maximum force and energy absorption. Moreover, with cutouts reduction, the failure modes of the samples changed from the diamond asymmetric mode and single-lobe mode to multi-lobes, and with removing cutouts, the failure mode is observed to be completely symmetric.

Single Molecule Analysis of differential functional mechanisms of MtRecG while being exposed to variants of stalled replication-fork

Helicases are motor proteins involved in multiple activities to carry out manipulation of the nucleic acids for efficient gene regulation. In case of roadblocks that can lead the replication machinery to get halted, a complex molecular surveillance system utilizing helicases as its key player ensures the halted fork to resume its duplication process. RecG, belonging to the category of Superfamily-2 plays a vital role in rescuing different kinds of stalled fork. Here, through adoption of single-molecule techniques we have attempted to probe the DNA unwinding features by RecG and tried to capture several stages of genetic rearrangement. An elevated processivity of RecG has been observed for the kinds of stalled fork where progression of lagging daughter strand is ahead than that of the leading strand. Through precise alteration of its function in terms of unwinding, depending upon the substrate DNA, RecG catalyzes the formation of Holliday junction from a stalled fork DNA. In summary, we have featured that RecG adopts asymmetric mode of locomotion to unwind the lagging daughter strand to facilitate Holliday junction creation which acts as a suitable intermediate for recombinational repair pathway.

An asymmetric mode-localized mass sensor based on the electrostatic coupling of different structural modes with distributed electrodes

Mode-localization sensor with amplitude ratio as output metric has shown excellent potential in the field of micro-mass detection. In this paper, an asymmetric mode -localized mass sensor with a pair of electrostatically coupled resonators of different thickness is proposed. Partially distributed electrodes are introduced to ensure the asymmetric mode coupling of second and third order modes while actuating the thinner resonator by the distributed electrode. The analytical dynamic model is established by Euler–Bernoulli theory and solved by harmonic balance method (HBM) combined with asymptotic numerical method (ANM). Detailed investigations on the linear and nonlinear behavior, critical amplitude as well as the sensitivity of the sensor are performed. The sensitivity of the proposed sensor can be enhanced by about 20 times compared to first order mode-localized mass sensors. Furthermore, by exploiting the nonlinearities while driving the device beyond the critical amplitude for the in-phase mode, the sensor performs a great improvement in sensitivity up to 1.78 times. Besides, the influence of the decrease of coupling voltage is studied, which gives a good reference to avoid mode aliasing.

Researching the Blocking of Current Protection of Electrical Power Units with Transformers

The magnetizing current inrush appears in electrical power units equipped with transformers in case of no-load energizing of the power transformers and in a number of other cases. This phenomenon could cause a false triggering of the current protection. To prevent incorrect actions of the current protection during the magnetizing current inrush a protection blocking is carrying out. The blocking principle operation is based on the fact that in a three-phase system in normal mode and in case of symmetrical short circuit the first harmonics contained in the phase currents of electrical installations form a direct sequence and the second ones – the negative sequences. In case of an asymmetric mode, including an asymmetric short circuit, the negative sequence appears, formed by the first harmonics that are part of the phase currents of the specified system. In magnetizing current inrush modes, second harmonics of significant magnitude are present in phase currents, which form the negative sequence. Based on the analysis of the information parameters of the specified sequences currents, identification of the magnetizing current inrush and short-circuit modes is performed with the implementation of the protection blocking if necessary. The study of the current protection blocking functioning was performed using computational experiment by analyzing the calculated changes of blocking parameter compared with the threshold setpoint. The specified researching is done by using the digital model that is implemented in the dynamic modeling environment MatLab-Simulink. As a result of the performed calculations, the principal operability of the proposed current protection blocking was confirmed that provides a fairly reliable identification of the magnetizing current inrush and short-circuits modes, regardless of the degree of saturation of current transformers. It was found that the proposed principle of the current protection blocking has a higher sensitivity in comparison with the classical one based on the estimation of the ratio of the second and first harmonics of the phase currents. In short-circuit modes in an electrical power units the proposed blocking causes a current protection operation delay that can be reduced by digital filters performance improvement.

A Novel Switched-Capacitor Multilevel Inverter Topology for Energy Storage and Smart Grid Applications

The recent advancement in the application of the internet of things in the smart grid has led to an industrial revolution in the power industry. The Industry 4.0 revolution has already set in, allowing computers to interact for an efficient and intelligent approach in solving smart grid issues. multilevel inverters (MLIs) are an integral part of the smart grid system for integrating the distributed generation sources and storage energy systems into the smart grid. It attracted attention in industrial applications as they can handle high power and high voltage with an inherent feature of superior output voltage waveform quality. Moreover, its variant, the switched-capacitor MLI (SCMLI), has the added benefit of lesser DC supply requirement. In this paper, a switched-capacitor multilevel inverter topology has been proposed, which can operate in symmetric and asymmetric mode. The proposed SCMLI generate thirteen and thirty-one level output voltages for symmetric and asymmetric selection of DC voltage sources, respectively. The proposed SCMLI has a smaller number of switching devices for a given output voltage level as compared to other recently proposed topologies. A thorough comparison is presented with the recently proposed topologies on several parameters, including cost function. To validate the proposed topology, symmetric and asymmetric cases were simulated using Matlab® 2018a and the results were verified using an experimental hardware setup.

Asymmetry-Induced Dynamics for a Class of Diode-Based Chaotic Circuits: A Case Study

We consider the modeling and asymmetry-induced dynamics for a class of chaotic circuits sharing the same feature of an antiparallel diodes pair as the nonlinear component. The simple autonomous jerk circuit of [J. Kengne, Z. T. Njitacke, A. N. Nguomkam, M. T. Fouodji and H. B. Fotsin, Coexistence of multiple attractors and crisis route to chaos in a novel chaotic jerk circuit, Int. J. Bifurcation Chaos Appl. Sci. Eng.26 (2016) 1650081] is used as the prototype. In contrast to current approaches where the diodes are assumed to be identical (and thus a perfect symmetric circuit), we examine the more realistic situation where the diodes have different electrical properties in spite of unavoidable scattering of parameters. In this case, the nonlinear component formed by the diodes pair displays an asymmetric current–voltage characteristic which induces asymmetry of the whole circuit. The model is described by a continuous-time 3D autonomous system (ODEs) with exponential nonlinearities. We examine the chaos mechanism with respect to system parameters both in the symmetric and asymmetric modes of operation by using bifurcation diagrams and phase space trajectory plots as the main indicators. Period doubling route to chaos, merging crisis, and multiple coexisting (i.e., two, four, or six) mutually symmetric attractors are reported in the symmetric mode of oscillation. In the asymmetric mode, several unusual nonlinear behaviors arise such as coexisting bifurcations, hysteresis, asymmetric double-band chaotic attractor, crisis, and coexisting multiple (i.e., two, three, four, or five) asymmetric attractors for some suitable ranges of parameters. Theoretical analyses and circuit experiments show a very good agreement. The results obtained in this work let us conjecture that chaotic circuits with antiparallel diodes pair are capable of much more complex dynamics than what is reported in the current literature and thus should be reconsidered accordingly in spite of the approach followed in this work.