Description Of Systems Research Articles

Characterizing Climatic Socio‐Environmental Tipping Points in Coastal Communities: A Conceptual Framework for Research and Practice

AbstractThe concept of climate tipping points in socio‐environmental systems is increasingly being used to describe nonlinear climate change impacts and encourage social transformations in response to climate change. However, the processes that lead to these tipping points and their impacts are highly complex and deeply uncertain. This is due to numerous interacting environmental and societal system components, constant system evolution, and uncertainty in the relationships between events and their consequences. In the face of this complexity and uncertainty, this research presents a conceptual framework that describes systemic processes that could lead to tipping points socio‐environmental systems, with a focus on coastal communities facing sea level rise. Within this context, we propose an organizational framework for system description that consists of elements, state variables, links, internal processes, and exogenous influences. This framework is then used to describe three mechanisms by which socio‐environmental tipping could occur: feedback processes, cascading linkages, and nonlinear relationships. We presented this conceptual framework to an expert panel of coastal practitioners and found that it has potential to characterize the effects of secondary climatic impacts that are rarely the focus of coastal risk analyses. Finally, we identify salient areas for further research that can build upon the proposed conceptual framework to inform practical efforts that support climate adaptation and resilience.

Методология матричного моделирования многокомпонентных многопоточных многоступенчатых энергетических комплексов

Traditionally, heat transfer problems are solved in relation to two-flow systems in which heat exchange is carried out between hot and cold coolants. However, along with two-flow systems, there are often multiflow systems in which the number of coolant flows is three or more. In addition, each energy carrier stream may consist of several components, and the installation may include several stages. Thus, the development of universal approaches and methods for modeling, calculation, and optimization of multi-component multiflow multistage energy complexes within the framework of a unified methodology is an urgent scientific and practical task. A methodology of matrix formalization of modeling heat and mass transfer processes is based on methods and approaches of matrix description of heat and mass transfer systems in energy complexes. The approaches and methods of modeling energy power installations are summarized. Within the framework of the matrix description methodology, the rules and approaches to the development of models of heat and mass transfer processes are formulated in relation to multicomponent multiflow multistage energy complexes. The authors have proposed a solution to the inverse problems with and without considering a phase transition in coolants. Analysis of formulated and solved problems within the framework of the proposed methodology allows us to recommend the use of methods and approaches of matrix modeling of equipment to solve direct and inverse problems for multicomponent multiflow multistage energy complexes for various purposes.

Spatially Resolved Near Field Spectroscopy of Vibrational Polaritons at the Small N Limit.

Vibrational polaritons, which have been primarily studied in Fabry-Pérot cavities with a large number of molecules (N ∼ 106-1010) coupled to the resonator mode, exhibit various experimentally observed effects on chemical reactions. However, the exact mechanism is elusively understood from the theoretical side, as the large number of molecules involved in an experimental strong coupling condition cannot be represented completely in simulations. This discrepancy between theory and experiment arises from computational descriptions of polariton systems typically being limited to only a few molecules, thus failing to represent the experimental conditions adequately. To address this mismatch, we used surface phonon polariton (SPhP) resonators as an alternative platform for vibrational strong coupling. SPhPs exhibit strong electromagnetic confinement on the surface and thus allow for coupling to a small number of molecules. As a result, this platform can enhance nonlinearity and slow down relaxation to the dark modes. In this study, we fabricated a pillar-shaped quartz resonator and then coated it with a thin layer of cobalt phthalocyanine (CoPc). By employing scattering-type scanning near-field optical microscopy (s-SNOM), we spatially investigated the dependency of vibrational strong coupling on the spatially varying electromagnetic field strength and demonstrated strong coupling with 38,000 molecules only-reaching to the small N limit. Through s-SNOM analysis, we found that strong coupling was observed primarily on the edge of the quartz pillar and the apex of the s-SNOM tip, where the maximum field enhancement occurs. In contrast, a weak resonance signal and lack of coupling were observed closer to the center of the pillar. This work demonstrates the importance of spatially resolved polariton systems in nanophotonic platforms and lays a foundation to explore polariton chemistry and chemical dynamics at the small N limit-one step closer to reconcile with high-level quantum calculations.

Microbiome modeling: a beginner's guide.

Microbiomes, comprised of diverse microbial species and viruses, play pivotal roles in human health, environmental processes, and biotechnological applications and interact with each other, their environment, and hosts via ecological interactions. Our understanding of microbiomes is still limited and hampered by their complexity. A concept improving this understanding is systems biology, which focuses on the holistic description of biological systems utilizing experimental and computational methods. An important set of such experimental methods are metaomics methods which analyze microbiomes and output lists of molecular features. These lists of data are integrated, interpreted, and compiled into computational microbiome models, to predict, optimize, and control microbiome behavior. There exists a gap in understanding between microbiologists and modelers/bioinformaticians, stemming from a lack of interdisciplinary knowledge. This knowledge gap hinders the establishment of computational models in microbiome analysis. This review aims to bridge this gap and is tailored for microbiologists, researchers new to microbiome modeling, and bioinformaticians. To achieve this goal, it provides an interdisciplinary overview of microbiome modeling, starting with fundamental knowledge of microbiomes, metaomics methods, common modeling formalisms, and how models facilitate microbiome control. It concludes with guidelines and repositories for modeling. Each section provides entry-level information, example applications, and important references, serving as a valuable resource for comprehending and navigating the complex landscape of microbiome research and modeling.

A new activity coefficient model for describing adsorbed phase nonidealities

The following study introduces a new adsorbed phase activity coefficient model, the SPLINT model, for describing nonideal multicomponent systems. The derivation is presented and simplification to the thermodynamically robust ABC model in the low‑coverage limit is shown. Both the SPLINT and ABC models are fit to 25 binary systems. Thermodynamic consistency of the data is established through multiple consistency tests including the intersection rule, closed‑loop reduced spreading pressure integration, the Gibbs‑Duhem integral equality, and alignment of pure and binary data. Regressed parameters are used in Real Adsorbed Solution Theory to predict both binary and ternary adsorption. The ABC and SPLINT models accurately describe systems with considerable nonideality when the activity coefficients are symmetric; however, the SPLINT model is required for accurate description of systems with complex, asymmetric activity coefficient behavior. The new model includes one more fitting parameter than the ABC model for a single binary system, but less across multiple data sets and higher‑order systems due to the theoretical basis. The importance of capturing activity coefficient asymmetry is demonstrated with a highly nonideal system across various pressures and temperatures measured by the present authors using the Integral Mass Balance method with HFC‑125 (pentafluoroethane), HFC‑32 (difluoromethane), and zeolite H‑ZSM‑5. The theoretical basis of the SPLINT model is further enforced by presenting two methods for predicting activity coefficients with the SPLINT model: correlating the fitting parameters individually and simultaneously regressing pure isosteric heat data to extract SPLINT fitting parameters. The study concludes with a discussion of pure and binary HFC‑125/HFC‑32 data with zeolite H‑ZSM‑5. A possible binary adsorption mechanism is proposed based on isosteric heat and excess enthalpy predictions and observed system irreversibility.

EXCOGITO, an Extensible Coarse-Graining Toolbox for the Investigation of Biomolecules by Means of Low-Resolution Representations.

Bottom-up coarse-grained (CG) models proved to be essential to complement and sometimes even replace all-atom representations of soft matter systems and biological macromolecules. The development of low-resolution models takes the moves from the reduction of the degrees of freedom employed, that is, the definition of a mapping between a system's high-resolution description and its simplified counterpart. Even in the absence of an explicit parametrization and simulation of a CG model, the observation of the atomistic system in simpler terms can be informative: this idea is leveraged by the mapping entropy, a measure of the information loss inherent to the process of coarsening. Mapping entropy lies at the heart of the extensible coarse-graining toolbox, EXCOGITO, developed to perform a number of operations and analyses on molecular systems pivoting around the properties of mappings. EXCOGITO can process an all-atom trajectory to compute the mapping entropy, identify the mapping that minimizes it, and establish quantitative relations between a low-resolution representation and the geometrical, structural, and energetic features of the system. Here, the software, which is available free of charge under an open-source license, is presented and showcased to introduce potential users to its capabilities and usage.

Fractional dynamics study: analytical solutions of modified Kordeweg-de Vries equation and coupled Burger’s equations using Aboodh transform

The study examines the using of Aboodh residual power series method and the Aboodh transform iteration method (ATIM) to analyze modified Korteweg-de Vries equation (mKdV) beside coupled Burger’s equations in the framework of the Caputo operator. These sets of equations represent the non-linear wave description for various physical systems. Through APM and ATIM, the solution for the coupled Burger’s equations and the mKdV equation get accurate dynamics information that will reveal the nature of their interactions. Using mathematically proven techniques and computational simulations, the developed methods’ efficiency and reliability are illustrated in the complex behaviors of these nonlinear wave equations, so that we can gain deeper insights into their complex dynamics. The research is aimed at an increase of the knowledge about the fractional calculus utilization for nonlinear wave motion and it also provides analytical tools for an analysis of wave acting in different scientific and engineering areas.

Deployment of Lean Manufacturing in Palm Oil Mill for Maximum Yield: A Case Study of Leading Palm Oil Producer in Nigeria

The deployment of lean manufacturing in the palm oil mill companyaimed at maximizing yield, was thoroughly investigated. The company has been experiencing a decline in palm oil production, adversely affecting productivity and customer satisfaction. The methodology employed for optimization encompassed a comprehensive system description, detailing the case study company's history, operational modalities, production machinery, and system challenges. To gather a holistic understanding of the company's current situation, data was meticulously collected through questionnaires, examination of company records, and other relevant sources. Microsoft excel software was then utilized to analyze the acquired data. The implementation of lean manufacturing tools, such as the fishbone diagram, identification of eight deadly wastesand takt-timeplayed a pivotal role in streamlining operations. In addition, a quantitative model of the supply chain was applied, utilizing critical path method (network analysis) to determine the optimal route. The results derived from the application of lean manufacturing tools and the supply chain quantitative model exhibited a remarkable improvement between (2012-2016) and (2018-2022). The average oil palm extraction increased substantially from 8.67% (2012-2016) to an impressive 30.52% (2018-2022). Furthermore, the management tools led to a significant reduction in machine downtimes, decreasing from an annual average of 5,498.6 hours to 2,472.4 hours. This improvement resulted in a considerable reduction in the annual total average cost of machine maintenance, plummeting from #1,899,578.6 to #261,853.8. The optimization efforts also extended to the supply chain, where selecting Path-2, exhibiting the least total supply time of 11 hours, significantly reduced the cost of supply from an average of #2,168,402 to #1,893,186. Overall, the net revenue of the company witnessed a remarkable surge of 71.99% post-implementation of these management tools. This comprehensive approach not only addressed production challenges but also had a substantial positive impact on the company’s financial performance. The strategic deployment of lean manufacturing emerged as a catalyst for sustainable growth and enhanced operational efficiency.

On [formula omitted]-performance of weakly-hard real-time control systems

This paper considers control systems with failures in the feedback channel, that occasionally lead to loss of the control input signal. A useful approach for modeling such failures is to consider window-based constraints on possible loss sequences, for example that at least r control attempts in every window of s are successful. A powerful framework to model such constraints are weakly-hard real-time constraints. Various approaches for stability analysis and the synthesis of stabilizing controllers for such systems have been presented in the past. However, existing results are mostly limited to asymptotic stability and rarely consider performance measures such as the resulting ℓ2-gain. To address this problem, we adapt a switched system description where the switching sequence is constrained by a graph that captures the loss information. We present an approach for ℓ2-performance analysis involving linear matrix inequalities (LMI). Further, leveraging a system lifting method, we propose an LMI-based approach for synthesizing state-feedback controllers with guaranteed ℓ2-performance. The results are illustrated by a numerical example.

Local dominance unveils clusters in networks

Clusters or communities can provide a coarse-grained description of complex systems at multiple scales, but their detection remains challenging in practice. Community detection methods often define communities as dense subgraphs, or subgraphs with few connections in-between, via concepts such as the cut, conductance, or modularity. Here we consider another perspective built on the notion of local dominance, where low-degree nodes are assigned to the basin of influence of high-degree nodes, and design an efficient algorithm based on local information. Local dominance gives rises to community centers, and uncovers local hierarchies in the network. Community centers have a larger degree than their neighbors and are sufficiently distant from other centers. The strength of our framework is demonstrated on synthesized and empirical networks with ground-truth community labels. The notion of local dominance and the associated asymmetric relations between nodes are not restricted to community detection, and can be utilised in clustering problems, as we illustrate on networks derived from vector data.

Clarification of the Nature of Quantum Theory Based on Scientific Philosophy

It is known that there was a disagreement between Bohr and Einstein about the nature of the fundamental equations of quantum mechanics. In 1949, in the work "Remarks on Articles," Einstein clearly expressed his thoughts on this issue. He wrote: "All this discussion was needed only to clarify the following. By attempting to defend the thesis that statistical quantum theory can in principle give a complete description of individual systems, we come to highly improbable theoretical concepts. On the other hand, the aforementioned interpretive difficulties of the theory disappear if quantum-theoretical descriptions are considered as descriptions of ensembles of systems"

A systematic DFT study of structure and electronic properties of titanium dioxide.

DFT functionals are of paramount importance for an accurate electronic and structural description of transition metal systems. In this work, a systematic analysis using some well-known and commonly used DFT functionals is performed. A comparison of the structural and energetic parameters calculated with the available experimental data is made in order to find the adequate functional for an accurate description of the TiO2 bulk and surface of both anatase and rutile structures. In the absence of experimental data on the surface energy, the theoretical predictions obtained using the high-accuracy HSE06 functional were used as a reference to compare against the surface energy values calculated with the other DFT functionals. A clear improvement in the electronic description of both anatase and rutile was observed by introducing the Hubbard U correction term to PBE, PW91, and OptPBE functionals. The OptPBE-U4 functional was found to offer a good compromise between accurately describing the structural and electronic properties of titania.

A Comprehensive Review of Existing and Pending University Campus Microgrids

Over the past few decades, many universities have turned to using microgrid systems because of their dependability, security, flexibility, and less reliance on the primary grid. Microgrids on campuses face challenges in the instability of power production due to meteorological conditions, as the output of renewable sources such as solar and wind power relies entirely on the weather and determining the optimal size of microgrids. Therefore, this paper comprehensively reviews the university campuses’ microgrids. Some renewable energy sources, such as geothermal (GE), wind turbine (WT), and photovoltaic (PV), are compared in terms of installation costs, availability, weather conditions, efficiency, environmental impact, and maintenance. Furthermore, a description of microgrid systems and their components, including distributed generation (DG), energy storage system (ESS), and microgrid load, is presented. As a result, the most common optimization models for analyzing the performance of campus microgrids are discussed. Hybrid microgrid system configurations are introduced and compared to find the optimal configuration in terms of energy production and flexibility. Therefore, configuration A (Hybrid PV- grid-connected) is the most common configuration compared to the others due to its simplicity and free-charge operation.

A new dual-frequency stratospheric–tropospheric and meteor radar: system description and first results

Abstract. A new dual-frequency stratospheric–tropospheric (ST) and meteor radar has been built and installed at the Langfang Observatory in northern China. It utilizes a new two-frequency system design that allows interleaved operation at 53.8 MHz for ST mode and at 35.0 MHz for meteor mode, thus optimizing performance for both ST wind retrieval and meteor trail detection. In dedicated meteor mode, the daily meteor count rate reaches over 40 000 and allows wind estimation at finer time resolutions than the 1 h typical of most meteor radars. The root mean square uncertainty of the ST wind measurements is better than 2 m s−1 when estimating the line of best fit with radiosonde winds. Preliminary observation results for 1 month of winter gravity wave (GW) momentum fluxes in the mesosphere, lower stratosphere and troposphere are also presented. A case of waves generated by the passage of a cold front is found.

Adaptive backstepping sliding mode subject-cooperative control for a pediatric lower-limb exoskeleton robot

The passive-assist rehabilitation mode with a fixed desired trajectory neglects the subject’s active involvement and degrades the therapeutic performance in case of partial muscle strength. Therefore, this study proposes a novel subject-cooperative control based on a variable admittance control scheme and a robust trajectory control scheme for a pediatric lower-limb exoskeleton robot. Initially, the system description and dynamic modeling are briefly explained. Thereafter, a neural-fuzzy–based variable admittance control ( nf VAC) is designed to incorporate a realistic subject-exoskeleton interaction and consider the subject’s active participation. Finally, a robust adaptive backstepping sliding mode control with rapid reaching law is used to handle parametric uncertainties and external disturbances. A stepwise selection of Lyapunov functions is utilized to address the stability of the trajectory control. The effectiveness of the proposed adaptive backstepping sliding mode–neural-fuzzy variable admittance control (ABSM- nf VAC) scheme is compared with two contrast control schemes, namely, adaptive backstepping-fixed admittance control (AB-FAC) and adaptive terminal sliding mode-fuzzy variable admittance control (ATSM- f VAC) for the active-assist mode with the effect of sudden reflex. Based on the numerical results, the suggested cooperative controller has demonstrated favorable tracking performance, compliant interaction, and safety aspects during gait training.

Problems and development prospects of “green” logistics of maritime transport in the Russian Federation

Shipping is one of the industries that lags far behind others in environmental sustainability, especially when it comes to reducing the harmful impact on the environment, which makes the problem relevant. The article presents the concept of “green” logistics and its principles used in business practices. Current key problems of maritime transport related to environmental logistics and new requirements of the International Maritime Organisation are described. The experience of applying “green” technologies by foreign companies in the maritime industry has been analysed. It shows that electrification and decarbonisation can be successfully introduced into business practice and lead to improved environmental performance. The state of seaport infrastructure and vessels in the Russian Federation was studied. Certain Russian projects following “green” logistics trends are presented with description of the implemented systems, technologies, and new equipment. Conclusions are made about the potential of “green” logistics in Russia in the future: reduction of negative environmental impact, increase of competitiveness of Russian companies and new opportunities for business development.

Revisiting thermodynamics in (LiF, NaF, KF, CrF2)–CrF3 by first-principles calculations and CALPHAD modeling

The thermodynamic description of the (LiF, NaF, KF, CrF2)–CrF3 systems has been revisited, aiming for a better understanding of the effects of Cr on the FLiNaK molten salt. First-principles calculations based on density functional theory (DFT) were performed to determine the electronic and structural properties of each compound, including the formation enthalpy, volume, and bulk modulus. DFT-based phonon calculations were carried out to determine the thermodynamic properties of compounds, for example, enthalpy, entropy, and heat capacity as functions of temperature. Phonon-based thermodynamic properties show a good agreement with experimental data of binary compounds LiF, NaF, KF, CrF3, and CrF2, establishing a solid foundation to determine thermodynamic properties of ternary compounds as well as to verify results estimated by the Neumann-Kopp rule. Additionally, DFT-based ab initio molecular dynamics (AIMD) simulations were employed to predict the mixing enthalpies of liquid salts. Using DFT-based results and experimental data in the literature, the (LiF, NaF, KF, CrF2)–CrF3 system has been remodeled in terms of the CALculation of PHAse Diagrams (CALPHAD) approach using the modified quasichemical model with quadruplet approximation (MQMQA) for liquid. Calculated phase stability in the present work shows an excellent agreement with experiments, indicating the effectiveness of combining DFT-based total energy, phonon, and AIMD calculations, and CALPHAD modeling to provide the thermodynamic description in complex molten salt systems.

Measurement of the superfluid fraction of a supersolid by Josephson effect.

A new class of superfluids and superconductors with spatially periodic modulation of the superfluid density is arising1-12. It might be related to the supersolid phase of matter, in which the spontaneous breaking of gauge and translational symmetries leads to a spatially modulated macroscopic wavefunction13-16. This relation was recognized only in some cases1,2,5-9 and there is the need for a universal property quantifying the differences between supersolids and ordinary matter, such as the superfluid fraction, which measures the reduction in superfluid stiffness resulting from the spatial modulation16-18. The superfluid fraction was introduced long ago16, but it has not yet been assessed experimentally. Here we demonstrate an innovative method to measure the superfluid fraction based on the Josephson effect, a ubiquitous phenomenon associated with the presence of a physical barrier between two superfluids or superconductors19, which might also be expected for supersolids20, owing to the spatial modulation. We demonstrate that individual cells of a supersolid can sustain Josephson oscillations and we show that, from the current-phase dynamics, we can derive directly the superfluid fraction. Our study of a cold-atom dipolar supersolid7 reveals a relatively large sub-unity superfluid fraction that makes realistic the study of previously unknown phenomena such as partially quantized vortices and supercurrents16-18. Our results open a new direction of research that may unify the description of all supersolid-like systems.

Open dynamics of entanglement in mesoscopic bosonic systems

A key issue in quantum information is finding an adequate description of mesoscopic systems that is simpler than full quantum formalism yet retains crucial information about non-classical phenomena like entanglement. In particular, the study of fully bosonic systems undergoing open evolution is of great importance for the advancement of photonic quantum computing and communication. In this paper, we propose a mesoscopic description of such systems based on boson number correlations. This description allows for tracking Markovian open evolution of entanglement of both non-Gaussian and Gaussian states and their sub-Poissonian statistics. It can be viewed as a generalization of the reduced state of the field formalism (Alicki 2019 Entropy 21 705), which by itself does not contain information about entanglement. As our approach adopts the structure of the description of two particles in terms of first quantization, it allows for broad intuitive usage of known tools. Using the proposed formalism, we show the robustness of entanglement against low-temperature damping for four-mode bright squeezed vacuum state and beam-splitted single photon. We also present a generalization of the Mandel Q parameter. Building upon this, we show that the entanglement of the state obtained by beam splitting of a single occupied mode is inherited from sub-Poissonian statistics of the input state.

Solidified microstructure and phase equilibria of the Cu–Cr–X (X=Mg, Y) ternary systems

The Cu–Cr alloys with magnesium and yttrium exhibit appealing high-strength and high-conductivity (HSHC) characteristics. Anticipated contributions to the design of HSHC copper alloys include new insights from understanding the phase equilibria, solidified microstructure, and thermodynamics of the Cu–Cr–X (X = Mg, Y) systems. Five Cu–Cr–Y alloys and three Cu–Cr–Mg alloys were melted through arc melting and powder metallurgy, respectively. An analysis was conducted on the primary phases and solidification path of the as-cast Cu–Cr–Y alloys. Five three-phase regions in the Cu–Cr–Y system and three in the Cu–Cr–Mg system at the isothermal sections of 673 K were identified using XRD and EPMA. No ternary compound was discovered among either of these systems. The agreement between the experimental data and the calculated isothermal sections and liquidus projection derived from the thermodynamic description of the binary systems is quite good. The investigation on phase equilibria in Cu–Cr–X (X = Mg, Y) systems in this study helps in developing the thermodynamic database for multi-component copper alloys.