Changes In External Parameters Research Articles

Determination of the Boundaries of Changes in External Parameters that Complicate the Calculation of the Suspension of Agricultural Machinery

Introduction. The article deals with the problem of calculating the strength of the shaft of the wheel drive of agricultural machinery. The strength conditions of both the maximum torque and the values of relative deformations of the shaft are taken into account. Aim of the Article. Of the research is to determine the limits of external influences on a structural element, caused by the distributed weight of the motor-tractor machinery, at which it is necessary to construct not only the torque and strain diagrams, but also to determine the extreme values at each section, where the strength index of the structure is nonlinear. Materials and Methods. In calculations, the main provisions of continuum mechanics, theory of machines and mechanisms, as well as the basics of design in mechanical engineering are used. Central attention is paid to the influence of external influencing factors on the character of internal force distribution in the shaft. Results. The obtained area of variation of parameters P-q allows us to determine the necessity of more detailed calculation of strength parameters of the considered part. This is due to the emergence of extreme areas outside the boundaries of individual areas of consideration of the shaft work. The results are presented as a two-dimensional graph of the ratio of external influences, at which the specified effect takes place. Discussion and Conclusion. In comparison with typical calculations, regulated by normative documents, the proposed algorithm at the preliminary stage allows to determine the cases when nonlinear regions of bending moment changes require additional investigations. The use of the proposed algorithm allows, without resorting to time-consuming numerical methods of calculating the strength indicators of a wheel drive shaft, such as the finite element method, to obtain a more detailed picture of the nature of distribution of internal forces and deformations in the part under study.

The effect of temperature on the nonlinear elasticity of a fault rock in dynamic acoustoelastic testing (DAET) experiments

Summary Dynamic nonlinear elasticity in rocks may play an important role in earth processes, such as earthquake nucleation. In order to understand how nonlinear elasticity occurs within the shallow crust, experiments are required that simulate the in situ conditions of intact crustal rocks. Additionally, exploring the behaviour of nonlinear elasticity in response to changes in external parameters (e.g., temperature and wave frequency) acts as a means to further illuminate the complex mechanisms which give rise to nonlinear elasticity in rocks. In this study, we perform dynamic acoustoelastic testing (DAET) experiments on an intact cataclasite from the damage zone of the Alpine Fault, New Zealand. By performing pump-probe DAET experiments inside a temperature-controlled chamber, we are able to investigate a rich variety of nonlinear behaviour as a function of temperature. We find that the magnitude of averaging softening, cubic nonlinearity, and hysteresis tend to increase as temperature increases from 20 to 110○C. In contrast, quadratic nonlinearity decreases with increasing temperature. These observations support the hypothesis that at least two distinct mechanisms control nonlinear phenomena in rocks. Nonlinear parameters show little to no dependence on frequency over the 200-600 Hz pump range, although values of the nonlinear parameter α are found to be nearly two orders of magnitude smaller than those determined using ultrasonic perturbations. Additionally, an analysis using different time windows shows that the surface waves of the ultrasonic probe sense greater nonlinearity compared to the direct P-wave due to differences in the polarisation and propagation paths. As well as providing further insight into the mechanisms responsible for nonlinear elasticity in rocks, our experiments show that nonlinear softening will increase as temperature increases in the damage zones of faults. This has potential implications for understanding earthquake nucleation processes.

DIAMOND + MEGAN Microbiome Analysis.

Metagenomics is the study of microbiomes using DNA sequencing technologies. Basic computational tasks are to determine the taxonomic composition (who is out there?), the functional composition (what can they do?), and also to correlate changes of composition to changes in external parameters (how do they compare?). One approach to address these issues is to first align all sequences against a protein reference database such as NCBI-nr and to then perform taxonomic and functional binning of all sequences based on their alignments. The resulting classifications can then be interactively analyzed and compared. Here we illustrate how to pursue this approach using the DIAMOND+MEGAN pipeline, on two different publicly available datasets, one containing short-read samples and other containing long-read samples.

Results of tests for abrasive wear on a VIM LTDS installation

A number of well-known methods of accelerated testing for relative wear resistance are considered including a procedure based on the Brinell-Howarth method for laboratory studies and implemented on a IM-01 facility (designed at WISHOM) in which a powder abrasive is used. The shortcomings of those methods are discussed. A new VIM LTDP installation is developed in which an abrasive tape (320 mm and 15 mm in length and width, respectively) with a grain size of P60 is used as an abrasive material. The degree of wear was determined by a decrease of the sample mass using weighing on a balance before and after testing with an accuracy of 0.0001 g. The test results were obtained as a relative wear resistance e equal to the ratio of the values of the wear resistance of the test and standard samples. Consideration of the relative wear resistance makes it possible to increase the accuracy of the results due to the exclusion of the effect of changes in external parameters which determine the wear rate during testing. The installation ensures accelerated testing of the samples, i.e., the time for testing one sample is about 5 min. The structure and the grain size of the working body, the load value in the contact zone and the speed of interaction between the sample and tool are preserved. The use of an abrasive tape with different grain size provides for application of the unit to a wide range of tasks using samples without any preliminary grinding, but with the obligatory preliminary cleaning of the samples from slags and large particles after application of wear-resistant coatings.

Nonlinear optical characteristics of thermodynamic effects- and electric field-triggered Mathieu quantum dot

In this work, the total refractive index (TRICs) and total absorption coefficients (TACs) of a spherical quantum dot with the Mathieu potential encompassement, generated by using InxGa1−xAs/GaAs heterostructure, and including hydrogenic impurity in its center, under the influence of the temperature, hydrostatic pressure and external electric field are investigated. The compact density matrix formalism and the iterative method are employed to compute the nonlinear optical features. The relevant eigenvalue equation of the Mathieu quantum dot (MQD) is solved by constructing a tridiagonal matrix formalism, within the effective mass approach. As well as the response of TRICs and TACs to external parameters, the alterations concerning structure parameters such as doping concentration and restriction width are also examined. To the best of our knowledge, the external influences and structural parameters on the optical specifications of MQD containing the central impurity are theoretically taken into consideration, for the first time, in the present work. Determining the optimality of optical properties arising from structural and external parameter changes is crucial in terms of providing a theoretical basis for the experimental production and practical use of MQD.

Green Transformation of Anti-Epidemic Supplies in the Post-Pandemic Era: An Evolutionary Approach.

Post-pandemic, the use of medical supplies, such as masks, for epidemic prevention remains high. The explosive growth of medical waste during the COVID-19 pandemic has caused significant environmental problems. To alleviate this, environment-friendly epidemic prevention measures should be developed, used, and promoted. However, contradictions exist between governments, production enterprises, and medical institutions regarding the green transformation of anti-epidemic supplies. Consequently, this study aimed to investigate how to effectively guide the green transformation. Concerning masks, a tripartite evolutionary game model, consisting of governments, mask enterprises, and medical institutions, was established for the supervision of mask production and use, boundary conditions of evolutionary stabilization strategies and government regulations were analyzed, and a dynamic system model was used for the simulation analysis. This analysis revealed that the only tripartite evolutionary stability strategy is for governments to deregulate mask production, enterprises to increase eco-friendly mask production, and medical institutions to use these masks. From the comprehensive analysis, a few important findings are obtained. First, government regulation can promote the green transformation process of anti-epidemic supplies. Government should realize the green transformation of anti-epidemic supplies immediately in order to avoid severe reputation damage. Second, external parameter changes can significantly impact the strategy selection process of all players. Interestingly, it is further found that the cost benefit for using environmentally friendly masks has a great influence on whether green transformation can be achieved. Consequently, the government should establish a favorable marketplace for, and promote the development of, inexpensive, high-quality, and effective environmentally friendly masks in order to achieve the ultimate goal of green transformation of anti-epidemic supplies in the post-pandemic era.

Non-Abelian braiding of Weyl nodes via symmetry-constrained phase transitions

Weyl semimetals are arguably the most paradigmatic form of a gapless topological phase. While the stability of Weyl nodes, as quantified by their topological charge, has been extensively investigated, recent interest has shifted to the manipulation of the location of these Weyl nodes for non-Abelian braiding. To accomplish this braiding it is necessary to drive significant Weyl node motion using realistic experimental parameter changes. We show that a family of phase transitions characterized by certain symmetry constraints impose that the Weyl nodes have to reorganise by a large amount, shifting from one high symmetry plane to another. Additionally, for a subset of pairs of nodes with nontrivial Euler class topology, this reorganization can only occur through a braiding process with adjacent nodes. As a result, the Weyl nodes are forced to move a large distance across the Brillouin zone and to braid, all driven by small temperature changes, a process we illustrate with Cd$_2$Re$_2$O$_7$. Our work opens up routes to readily manipulate Weyl nodes using only slight external parameter changes, paving the way for the practical realization of reciprocal space braiding.

Decision Making in Geotechnical Monitoring Systems

The article considers an algorithm for estimating the moments of correction of the list of controlled and measured parameters, selecting control points and correcting an individual model of a geotechnical object. As a criterion for correcting the list of parameters, it is proposed to use the moments when the values of the controlled parameters approach the critical zone. The choice of parameters for measurement is carried out on the basis of optimization of the ratio of the cost of monitoring to possible damage. The definition of key control zones is carried out according to the criterion of sensitivity of monitoring zones to changes in external parameters. The practical verification was carried out on the data of geotechnical monitoring of a three-storey building in which destructive processes were recorded.

Complex and yet predictable: The message of the 2021 Nobel Prize in Physics

Syukuro (Suki) Manabe, Klaus Hasselmann, and Georgio Parisi were awarded the 2021 Nobel Prize in Physics. At first blush, this prize appears to recognize unrelated work in disparate fields. Even one of the Nobel Committee members acknowledged in the postannouncement press conference that it looks like a “split prize.” Upon reflection, however, there is a common thread running through the works of the awardees. Simply put, this year’s prize in physics acknowledges that disordered systems are predictable and that systems that behave chaotically can respond predictably to changes in external parameters. Earth’s climate is one such complex system, and it is of great importance to humanity. Its future must be predicted to guide policy. The prize also acknowledges that changes in the climate, like the properties of disordered condensed matter, are predictable using methods grounded in sound physics. Therefore, it is very appropriate to jointly recognize the foundational work done by these three visionary researchers with the Nobel Prize in Physics. This Nobel Prize in Physics is very different from the earlier Nobel Peace Prize awarded in 2007 to former Vice President Al Gore and the Intergovernmental Panel on Climate Change (IPCC), which recognized the importance of human-induced climate change and the actions needed to understand and mitigate it. It is also different from the 1995 Nobel Prize in Chemistry to Profs. Rowland, Molina, and Crutzen for their work on a global environmental problem arising from ozone depletion by manufactured chemicals, some of which were also major greenhouse gases. In contrast to those two earlier awards, the 2021 Nobel Prize in Physics recognizes the fundamental scientific basis of climate predictability, detection of change due to known external forcings, and the predictability of disordered condensed matter. Syukuro Manabe. Image credit: Denise Applewhite (Princeton University, Princeton, NJ). Climate scientists Syukuro Manabe and … [↵][1]1To whom correspondence may be addressed. Email: a.r.ravishankara{at}colostate.edu. [1]: #xref-corresp-1-1

Technique for accelerated tests of samples for wear resistance

A review of the existing methods of accelerated abrasive wear tests is presented. The shortcomings of the technique implemented on an IM-01 installation of the VISKHOM design, as well as the Brinell-Howarth technique for laboratory studies, in which a powder abrasive is used are discussed, e.g., a problem of a uniform distribution of a free-flowing abrasive material over the surface of the contact zone, as well as problems of ensuring the stability of the supply of the abrasive material during the experiment. The goal of the study is to develop a methodology for comparative assessment of the wear resistance, excluding noted shortcomings. The tests were carried out on an M-1 installation using plate specimens 60 × 40 × 3 mm. The abrasive material used was a radial flap wheel 150 – 220 mm in diameter (width 30 mm, bore diameter 30 – 40 mm). The degree of wear was determined by a decrease in the mass of the sample by weighing on a balance with an accuracy of 0.1 mg before and after testing. The test results were considered as a relative wear resistance ε equal to the ratio of the wear resistance of the test specimen to the wear resistance of the reference one. The use of relative wear resistance makes it possible to increase the accuracy of the results obtained due to elimination of the influence of natural changes in external parameters that determine the intensity of wear during the test. The developed installation provides significant shortening of the accelerated comparative test (8 min) compared to 40 min on an IM-1, the structure and grain size of the working fluid, the constancy of the load in the contact zone and the speed of interaction between the sample and the tool being the same. Flap wheels of various grain sizes provide application of the device to a wide range of tasks without preliminary grinding of the samples and necessitate only their preliminary cleaning from slags and large particles after applying wear-resistant coatings.

НОВОЕ УСТРОЙСТВО И ПОРЯДОК СРАВНИТЕЛЬНЫХ ИСПЫТАНИЙ АБРАЗИВНОЙ ИЗНОСОСТОЙКОСТИ ПОКРЫТИЙ СТАЛИ 65Г, ПОЛУЧЕННЫХ СКОРОСТНЫМ ТВЧ-БОРИРОВАНИЕМ

Abrasive wear tests are a complex, time-consuming and long-term type of research on the wear-resistant properties of materials. Known methods for the experimental determination of the wear resistance of materials based on abrasive wear require an assessment of the wear resistance corresponding to the characteristics of field tests of parts with reinforcing coatings applied using high- frequency currents. (Research purpose) The research purpose is in analyzing the existing methods of testing for abrasive wear in the development of technological processes to increase the wear resistance of the surfaces of machine parts in comparison with the methodology developed by VIM, as well as comparing the methods of laboratory tests and field tests with the method proposed in this paper. (Materials and methods) Authors chose the IM-01 installation of the VISKHOM design for laboratory research, which uses powder abrasive. The article describes the most similar methods of foreign authors. The drill bits of Amazone seeders were strengthened according to the selected testing technology. The plates with a size of 60x40 and a thickness of 5-7 millimeters were selected as samples for testing the relative wear resistance. According to the VIM method, an abrasive radial petal circle is used as an abrasive material on the M-1 installation. (Results and discussion) The test results are expressed by the relative wear resistance index ε, which is equal to the ratio of the wear resistance of the test sample to the wear resistance of the standard. The use of the relative wear resistance index allows to increase the accuracy of the results obtained due to the exclusion of the influence of natural changes in external parameters that determine the wear rate during the test. (Conclusions) The proposed device makes it possible to provide accelerated comparative tests of samples and improve the stability of obtaining wear characteristics in a relatively short time (with the practical use of the device, the time spent on testing of one sample was about 8 minutes).

An Efficient Spiking Neuron Hardware System Based on the Hardware-Oriented Modified Izhikevich Neuron (HOMIN) Model

Mathematical modifications have been made to the Izhikevich Neuron Model to allow for a simple, low-area digital hardware implementation with low computational intensity. The implemented neuron circuit only requires one input parameter to replicate all of the cortical neuron behaviours described by Izhikevich. The low hardware requirements of this neuron implementation make large, highly parallel digital spiking neural networks of this neuron feasible. Additionally, the model requires fewer external parameter changes to exhibit diverse neuron behaviours. The alterations made to create this novel model are presented in detail with a performance comparison to the original Izhikevich Neuron. Subsequently a digital hardware realization is presented and its performance is characterized.

FBG Sensors for Environmental and Biochemical Applications—A Review

Sensors play a large role in monitoring and ensuring that environmental parameters satisfy industrial requirements. They offer crucial safety measures in the early detection of hazards. Conventional electrical sensors possess several drawbacks that hinder their use in environmental sensing. Research has explored and optimized optical-based sensors because they are more robust, immune to electromagnetic interference and offer multiplexing capabilities for sensor arrays accompanied by ease of modification to cater to different measurands. Fibre Bragg grating is the perturbation of the refractive index imprinted within the core of an optic fibre via an intense UV laser. The gratings, when perturbed by external parameter changes, will induce a shift in their wavelength, indicating detection. With modifications such as hygroscopic coating and different grating profile imprinting, FBG can detect various physical and chemical parameters. Environmental, pharmaceutical and biochemical fields can benefit from FBG sensing because their parameters affect not only their product quality but also the lives of consumers. This review discusses some of the FBG sensors that have been proposed to serve in environmental and biochemical applications.

High-sensitivity refractometric sensing with an indirectly coupled active and passive microresonator-waveguide system

We investigate high-sensitivity refractometric sensing with indirectly coupled active and passive optical microresonators mediated by drop-filter waveguides. It is shown that the line shape and amplitude of power reflection and transmission spectra are relevant with both phase delay and gain of microresonators, and high-sensitivity refractometric sensing may be realizable with three enhancement mechanisms, i.e., phase delay-induced sharp Fano spectra, gain-induced narrow-linewidth Lorentzian spectra, and exceptional points (EPs). Between the former two enhancement mechanisms, the competitive relationship, which is determined by the interplay of phase delay and gain, exists. The system could be tuned into the vicinity of the EP by choosing appropriate phase delay and gain. As the system response to the slight change of external parameter is evidently benefiting from the critical behavior, ultrahigh-sensitivity refractometric sensing could be realizable due to the dynamical amplification effect.

Quench dynamics in one-dimensional optomechanical arrays

Non-equilibrium dynamics induced by rapid changes of external parameters is relevant for a wide range of scenarios across many domains of physics. For waves in spatially periodic systems, quenches will alter the bandstructure and generate new excitations. In the case of topological bandstructures, defect modes at boundaries can be generated or destroyed when quenching through a topological phase transition. Here, we demonstrate that optomechanical arrays are a promising platform for studying such dynamics, as their bandstructure can be tuned temporally by a control laser. We study the creation of nonequilibrium optical and mechanical excitations in 1D arrays, including a bosonic version of the Su-Schrieffer-Heeger model. These ideas can be transferred to other systems such as driven nonlinear cavity arrays.

Rate of Formation and Decomposition of Gas Hydrate Formed in the Natural Coal

The paper presents experimental research on physical processes occurring in the black coal – natural gas system when external parameters change. It was shown that when thermobaric conditions corresponding to the area of stable hydrate existence are created, methane hydrate and carbon dioxide hydrate are formed in the internal space of the natural coal. Decomposition of methane hydrate in the coal occurs near the equilibrium curve, and the process of hydrate formation begins in the case of overcooling by 3–7°С and lasts several dozen hours. For the examined cases, the rate of gas hydrate decomposition in the coal is determined by the rate of change in external parameters during linear increase in temperature from 1 to 6°С/h.

Management strategy for innovation and investment activities of an enterprise

The purpose of this paper is to develop a strategy for managing the innovation and investment activity of an industrial enterprise at various stages of its life cycle. Based on the analysis and assessment of the efficiency of the implementation of existing strategies, the relevant features of innovation and investment activities of enterprises have been identified. A methodological approach to assessing the meso- and macroeconomic effect of the implementation of transformations at the enterprise depending on the stage of the life cycle is proposed, and an algorithm for determining the most optimal development strategy, which is based on an analysis of the parameters of predicted stability, is compiled. As a result of the study, a new approach to the formation of innovative and investment development of an enterprise was formed, which allows taking into account not only the change in the internal indicators of the economic activity of an enterprise, but also the change in external parameters. In addition, the proposed approach allows determining the economic effect on the basis of a combined assessment of the dynamics of introducing product, technological and managerial innovations, taking into account the efficiency of attracting investment resources that ensure the implementation of innovative transformations.

The Role of the Southern Ocean in Abrupt Transitions and Hysteresis in Glacial Ocean Circulation

AbstractHigh‐latitude Northern Hemisphere climate during the last glacial period was characterized by a series of abrupt climate changes, known as Dansgaard‐Oeschger events, which were recorded in Greenland ice cores as shifts in the oxygen isotopic composition of the ice. These shifts in inferred Northern Hemisphere high‐latitude temperature have been linked to changes in Atlantic meridional overturning strength. The response of ocean overturning circulation to forcing is nonlinear and a hierarchy of models have suggested that it may exist in multiple steady state configurations. Here, we use a time‐dependent coarse‐resolution isopycnal model with four density classes and two basins, linked by a Southern Ocean to explore overturning states and their stability to changes in external parameters. The model exhibits hysteresis in both the steady state stratification and overturning strength as a function of the magnitude of North Atlantic Deep Water formation. Hysteresis occurs as a result of two nonlinearities in the model—the surface buoyancy distribution in the Southern Ocean and the vertical diffusivity profile in the Atlantic and Indo‐Pacific basins. We construct a metric to assess circulation configuration in the model, motivated by observations from the Last Glacial Maximum, which show a different circulation structure from the modern. We find that circulation configuration is primarily determined by North Atlantic Deep Water density. The model results are used to suggest how ocean conditions may have influenced the pattern of Dansgaard‐Oeschger events across the last glacial cycle.

Problem of Energy and the Second Law of Thermodynamics

Receipt of heat in a thermodynamic system is defined by a Pfaffian form. For the heat-insulated systems it is equal to zero. Cooling of such system as a result of cyclic change of external parameters is usually considered to be impossible. It is offered to carry out full transformation of heat of the environment to work by means of thermally heterogeneous converter containing two gases with different thermal capacities divided by a mobile heatimpenetrable partition. As a result of cyclic change of external parameters along with production of work one gas is cooled, and another — heats up. The possibility of this process is caused by the fact that the entropy of a multiple parameter system cannot be generally defined.

Steady and transient operation of an organic Rankine cycle power system

Abstract The Organic Rankine Cycle (ORC) driven by low-grade energy can operate in off-grid mode. Here, we report the steady and transient characteristics of an ORC system. A single screw expander and a synchronous generator convert mechanical power to electricity. A lamp array simulates the variable external loads. The quality parameters including electric frequency, electric power and effective voltage are measured by a power meter. We show that at setting frequency of 50 Hz, the maximum system efficiency can be reached when the external load is not larger than the ORC power capacity. The expander isentropic efficiency is above 80% for the vapor superheating of 5–10 K at expander inlet. A control strategy is proposed to achieve better system performance under varied heat source and environment conditions. By use of residual frequency and adjusting pumping frequency, the vapor pressure at expander inlet can be automatically adjusted to reach the optimal value. Transient tests indicate that the electric quality is insensitive to the step change of external loads and heat/cold sources parameters. The thermohydraulic parameters are self-adapted to the change of external parameters. This work provides a self-adapting strategy for ORC operation at varied heat/cold source parameters.