System Partitioning Research Articles

Partitioning of SWCNT mixtures using amphiphilic carbohydrate-based surfactants

Single-walled carbon nanotubes (SWCNTs) have substantial application potential in many branches of technology. Considering that the spatial order of carbon atoms in SWCNTs determines their properties, the characteristics of a material can be adjusted for a specific application by using only selected types of SWCNTs. Unfortunately, SWCNT purification is challenging as the mechanisms of the currently available sorting techniques are not fully understood. The aqueous two-phase extraction (ATPE) method is a promising approach in this context as it offers SWCNT separation in an aqueous environment, so elucidation of its workings is essential. To come closer to achieving this goal, we synthesized a new range of surfactants based on ionic liquids equipped with amphiphilic carbohydrate moieties. We then examined how the modification of their structure influences SWCNT partitioning in two-phase systems composed of poly(ethylene glycol) and dextran. We concluded that the capacity of the ATPE method for purification of SWCNTs depended upon establishing a sufficient degree of order or disorder in the aqueous medium caused by the introduction of chemical compounds of a kosmotropic and chaotropic nature, respectively.

Generalized sequential state equation method for moving subsystem-induced structural parametric resonance

Parametric excitation is a unique type of excitation that arises from the time-varying parameters of a dynamical system, typically induced by the periodic movements of the system components. However, the structure-moving subsystems problem creates a new type of parametric excitation where the subsystems do not have exact periodic movements. Under the circumstances, dimension of the mathematical model of such a system exhibits time dependency, which prohibits the employment of conventional analytical methods to predict its stability. In this paper, we propose a novel Generalized Sequential State Equation Method that provides a distinct solution framework for analysis of the subsystem-induced parametric resonance. With the time-domain system partition and state mapping, the proposed method reconfigures the coupled system with a sequence of state space equations and solves them chronologically. The proposed method relaxes the single-subsystem-assumption in its original form and applies to a general scenario where the subsystems travel with arbitrary characteristic period. With the proposed method, occurrences of the subsystem-induced parametric resonance are precisely predicted via a set of analytical stability criteria and the steady state response is determined in an exact analytical form.

Interaction Parameters for the Formation of Mixed Micelles and Partitioning of Solutes in Them: A Review

When two or more surfactants are mixed, the critical micelle concentration and solubilization capability are changed, and a careful selection of the combination promotes the micelle formation and enhances the solubilizing capability. Thus, understanding the mechanism behind the phenomena is essential for controlling the physical properties of the mixed micelle. The interaction parameters β and B that describe the formation of mixed micelles and their partitioning of solutes, respectively, were proposed by Treiner four decades ago. In this work, data on the formation and partitioning in binary surfactant systems were collected. Although the data on the parameters β and B for polar solutes and theoretical development are still insufficient, the directions of research to acquire an in-depth understanding of the formation and partitioning of the mixed micelle are proposed.

Optimal Service Area Partitioning for Wireless Communication Systems and a Multibeam Antenna with Contoured Beams for the Equipotential Coverage of This Area

Optimal Service Area Partitioning for Wireless Communication Systems and a Multibeam Antenna with Contoured Beams for the Equipotential Coverage of This Area

Maximizing blue energy: the role of ion partitioning in nanochannel systems.

This study describes a numerical analysis on blue energy generation using a charged nanochannel with an integrated pH-sensitive polyelectrolyte layer (PEL), considering ion partitioning effects due to permittivity differences. The mathematical model for ionic and fluidic transport is solved using the finite element method, and the model validation is performed against existing theoretical and experimental results. The study investigates the influence of electrolyte concentration, permittivity ratio, and salt types (KCl, BeCl2, AlCl3) on the energy conversion process. The findings illustrate the substantial role of ion partitioning in modulating ionic concentration and potential fields, thereby affecting current profiles and energy conversion efficiencies. Remarkably, overlooking ion partitioning leads to significant overestimations of power density, highlighting the necessity of this consideration for accurate device performance predictions. This work introduces a promising configuration that achieves higher power densities, paving the way for the next generation of efficient energy-harvesting devices. The findings offer valuable insights into the development of state-of-the-art blue energy harvesting nanofluidic devices, advancing sustainable energy production.

On the notion of strong correlation in electronic structure theory.

Strong correlation has been said to have many faces, and appears to have many synonyms of questionable suitability. In this work we aim not to define the term once and for all, but to highlight one possibility that is both rigorously defined and physically transparent, and remains so in reference to molecules and quantum lattice models. We survey both molecular examples - hydrogen systems (Hn, n = 2, 4, 6), Be2, H-He-H, and benzene - and the half-filled Hubbard model over a range of correlation regimes. Various quantities are examined including the extent of spin symmetry breaking in correlated single-reference wave functions, energetic ratios inspired by the Hubbard model and the Virial theorem, and metrics derived from the one- and two-electron reduced density matrices (RDMs). The trace and the square norm of the cumulant of the two-electron reduced density matrix capture what may well be defined as strong correlation. Accordingly, strong correlation is understood as a statistical dependence between two electrons, and is distinct from the concepts of "correlation energy" and more general than entanglement quantities that require a partitioning of a quantum system into distinguishable subspaces. This work enables us to build a bridge between a rigorous and quantifiable regime of strong electron correlation and more familiar chemical concepts such as anti-aromaticity in the context of Baird's rule.

Toward Data Integrity Attacks Against Distributed Dynamic State Estimation in Smart Grid

With the continuous expansion of the power grid nodes scale, traditional centralized state estimation method shows certain limitations in estimation efficiency and accuracy. Recently, some power grids adopt a distributed state estimation method, in which each partition independently estimates the partial state information by partitioning the entire power system. However, the deviation of the state estimation in certain partition will result in the deviation of the estimation results in the entire power grid system. In this paper, we propose the attack strategy against the distributed state estimation in smart grids from two perspectives, i.e. the attack against local physical measurement value of the power system partition and the attack against the measurement value of coordination center. Moreover, the theoretical analysis of the state estimation deviation caused by the proposed data integrity attack and the propagation processes of proposed attack vectors in measurement calculations are formalized. The effectiveness of the proposed attack strategy is verified in the IEEE-30 bus and IEEE-118 bus systems. Simulation results show that attacking against a certain partition of a distributed system can indirectly affect the state estimation results of other partitions and attacking against the measurement value of coordination center can directly threaten the state estimation results of the entire power grid. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This paper proposes two attack strategies against the distributed state estimation of power grid from two perspectives, i.e. the attack against local physical measurement value of the power system partition and the attack against the measurement value of coordination center. Most of the previous works fail to formalize the state estimation deviation of both partial and entire state estimation results of power grid after the attacker launches the attack against the distributed state estimation. We formalize the state estimation deviation caused by the proposed data integrity attack and the propagation processes of proposed attack vectors in measurement calculations. The effectiveness of the proposed attack strategy against the state estimation of power grid is verified in the IEEE-30 bus and IEEE-118 bus systems. Simulation results show that attacking against a certain partition of power grid can indirectly cause the deviation in the state estimation results of entire power grid and attacking against the measurement value of the coordination center can directly threaten the state estimation results of the entire power grid. In conclusion, the proposed attack strategies are helpful for the research community to design detection strategies in a targeted manner and can be conveniently applied to the real-world security management system of smart grid.

Power supply restoration strategy of distribution system considering load demand response

The fluctuation of new energy output decreases distribution system reliability and increases the risk of a power outage. Based on this, considering the participation of new energy sources, the influence of load participation demand response on the distribution system is analyzed, the load demand response model is established, and the corresponding unit capacity compensation cost model is proposed. Considering the recovery income, operation cost, demand response compensation cost, and risk, a bi-level optimization model is established to solve the maximum recovery net income of the system. The upper layer aims at maximizing the expected net recovery income of the entire distribution system and proposes a distribution system partition scheme that takes into account the participation of new energy sources and mobile sources. The lower layer aims at maximizing the net recovery income of each partition and solves the recovery time and recovery amount of the load in each partition or the response time and response amount of the load participating in demand response under the condition of limited resources. Finally, the effectiveness of the power supply recovery optimization strategy of the distribution system proposed in this paper is verified by an example.

Geophysics‐Informed Hydrologic Modeling of a Mountain Headwater Catchment for Studying Hydrological Partitioning in the Critical Zone

AbstractHydrologic modeling has been a useful approach for analyzing water partitioning in catchment systems. It will play an essential role in studying the responses of watersheds under projected climate changes. Numerous studies have shown it is critical to include subsurface heterogeneity in the hydrologic modeling to correctly simulate various water fluxes and processes in the hydrologic system. In this study, we test the idea of incorporating geophysics‐obtained subsurface critical zone (CZ) structures in the hydrologic modeling of a mountainous headwater catchment. The CZ structure is extracted from a three‐dimensional seismic velocity model developed from a series of two‐dimensional velocity sections inverted from seismic travel time measurements. Comparing different subsurface models shows that geophysics‐informed hydrologic modeling better fits the field observations, including streamflow discharge and soil moisture measurements. The results also show that this new hydrologic modeling approach could quantify many key hydrologic fluxes in the catchment, including streamflow, deep infiltration, and subsurface water storage. Estimations of these fluxes from numerical simulations generally have low uncertainties and are consistent with estimations from other methods. In particular, it is straightforward to calculate many hydraulic fluxes or states that may not be measured directly in the field or separated from field observations. Examples include quickflow/subsurface lateral flow, soil/rock moisture, and deep infiltration. Thus, this study provides a useful approach for studying the hydraulic fluxes and processes in the deep subsurface (e.g., weathered bedrock), which needs to be better represented in many earth system models.

Trace element partitioning in basaltic systems as a function of oxygen fugacity

Along with temperature, pressure and melt chemistry, magmatic oxygen fugacity (fO2) has an important influence on liquid and solid differentiation trends and melt structure. To explore the effect of redox conditions on mineral stability and mineral-melt partitioning in basaltic systems we performed equilibrium, one-atmosphere experiments on a picrite at 1200–1110 °C with fO2 ranging from NNO-4 log units to air. Clinopyroxene crystallizes from 1180 °C to near-solidus, along with plagioclase, olivine and spinel. Olivine Mg# increases with increasing fO2, eventually reacting to pigeonite. Spinel is absent under strongly reducing conditions. Mineral-melt partition coefficients (D) of redox-sensitive elements (Cr, Eu, V, Fe) vary systematically with fO2 and, in some cases, temperature (e.g. DCr in clinopyroxene). Clinopyroxene sector zoning is common; sectors along a- and b-axes have higher AlIV, AlVI, Cr and Ti and lower Mg than c-axis sectors. In terms of coupled substitutions, clinopyroxene CaTs (MgSi = AlVIAlIV) prevails under oxidized conditions (≥ NNO), where Fe3+ balances the charge, but is limited under reduced conditions. Overall, AlIV is maximised under high temperature, oxidizing conditions and in slowly grown (a–b) sectors. High AlIV facilitates incorporation of REE (REEAlIV = CaSi), but DREE (except DEu) show no systematic dependence on fO2 across the experimental suite. In sector zoned clinopyroxenes enrichment in REE3+ in Al-rich sectors is quantitatively consistent with the greater availability of suitably-charged M2 lattice sites and the electrostatic energy penalty required to insert REE3+ onto unsuitably-charged M2 sites. By combining our experimental results with published data, we explore the potential for trace element oxybarometry. We show that olivine-melt DV, clinopyroxene-melt DV/DSc and plagioclase-melt DEu/DSr all have potential as oxybarometers and we present expressions for these as a function of fO2 relative to NNO. The crystal chemical sensitivity of heterovalent cation incorporation into clinopyroxene and the melt compositional sensitivity of the Eu2+–Eu3+ redox potential limit the use of clinopyroxene-melt and plagioclase-melt, however, olivine-melt DV affords considerable precision and accuracy as an oxybarometer that is independent of temperature, and crystal and melt composition. Variation of DV and DV/DSc with fO2 for olivine and clinopyroxene contains information on redox speciation of V in coexisting melt. By comparing the redox speciation constraints from partitioning to data from Fe-free synthetic systems and XANES spectroscopy of quenched glasses, we show that homogenous equilibria involving Fe and V species modify V speciation on quench, leading to a net overall reduction in the average vanadium valence. Mineral-melt partitioning of polyvalent species can be a useful probe of redox speciation in Fe-bearing systems that is unaffected by quench effects.

Effect of linalool on lamellar-structured emulsions: From molecular organization to organoleptic properties

An original approach has been developed to investigate the behaviour of linalool, a volatile compound widely used in the flavour and fragrance industry, incorporated in a model lamellar emulsion stabilized by an alkyl polyglucoside (APG). The surface activity of amphiphilic linalool was first studied in aqueous solutions, to predict its partition in multiphase colloidal systems. Results showed the high interfacial activity of linalool and its ability to act as a co-surfactant. The air/matrix partition coefficient was determined using headspace gas chromatography (HS-GC) and highlighted the different interactions between linalool and the emulsion phases. The molecular organization of lamellar emulsions was affected by the addition of linalool, as evidenced by combined microscopic observations, static light scattering (SLS) and X-ray diffraction measurements. As microstructure and rheological properties are closely linked, the viscoelastic properties of the samples were also investigated. The particle diameter, viscoelastic parameters and consistency of the emulsions were found to decrease with the addition of linalool. Finally, some textural and sensory properties of emulsions were evaluated and showed that the effect of linalool on the microstructure of the samples could also be perceived at the macroscopic scale, on their organoleptic properties. Our original approach could be used as a powerful tool for the future development of flavoured or fragranced emulsions.

On coherent states description of exciton systems: NLSE equations and hydrodynamics

The exciton system is described by means of specially constructed coherent states (CS), according to an idea of L.V. Keldysh long ago. The system is analyzed from the geometric point of view and from the relevant symmetry group contained in the displacement operator as generador of the CS system in the Klauder–Perelomov sense. Explicitly important quantities involving the quantum statistics of the system (partition function, mean density n and the Yuen limit) are calculated and briefly discussed in relation to the known case of pure bosons (e.g. photons). The Bogoliubov type transformations for the field operators of the Wannier–Mott type exciton system are presented in an exact way (in sharp contrast with the case of kel where only a rough approximation was given) showing how these transformations induce nonlinearity (cubic at first order) in the Schrodinger equation of the system. The conditions for a hydrodynamic description of the original Keldysh model, as the possibility of a BEC (Bose–Einstein Condensation), are discussed.

An ADMM-based power system partitioned black-start and parallel restoration method considering high-penetrated renewable energy

The large-scale blackouts after natural disasters have attracted much more concern these days. When a blackout occurs in a power transmission system, the whole system will be decomposed into several sub-systems and take much more time to recover. As the capacity of renewable energy continues to increase, the difficulties of the black start and restoration for a power transmission system also keep intensifying. To this end, this paper proposes a power transmission system partitioned black-start and restoration method while applying renewable energy sources to support and improve the recovery process. We first establish the power system black-start and restoration model and linearize the power flow constraints and unit generation constraints. Considering the power system can be decomposed into several sub-systems with high-capacity renewable energy sources, we propose a system partitioning method and a two-level parallel restoration model. The model realizes the independent restoration of each sub-system and is solved by the alternating direction multipliers method. Case studies on a modified New England 39-bus power system and a practical power system verify that the proposed method can offer high feasibility and effectiveness for power transmission systems with high-penetrated renewable energy sources when facing a large-scale blackout.

A source- and channel-coding approach to the analysis and design of languages and ideographies.

Can we explain the advantage natural languages enjoy over ideographies in a way that enables us to attempt the design of an ideography that "works"? I deploy an adapted version of Shannon's source- and channel-coding partitioning of a communication system to explain the communicative dynamics and shortfalls of ideographies, and reveal ways in which entrenchable, generalist ideographies could be designed.

Automated, Consistent, and Even-Handed Selection of Active Orbital Spaces for Quantum Embedding.

A widely used strategy to reduce the computational cost of quantum-chemical calculations is to partition the system into an active subsystem, which is the focus of the computational efforts, and an environment that is treated at a lower computational level. The system partitioning is mostly based on localized molecular orbitals. When reaction paths or energy differences are to be calculated, it is crucial to keep the orbital space consistent for all structures. Inconsistencies in orbital space can lead to unpredictable errors on the potential energy surface. While successful strategies to ensure this consistency have been established for organic and even metal-organic systems, these methods often fail for metal clusters or nanoparticles with a high density of near-degenerate and delocalized molecular orbitals. However, such systems are highly relevant for catalysis. Accurate yet feasible quantum-mechanical ab initio calculations are therefore highly desired. In this work, we present an approach based on the subsystem projected atomic orbital decomposition algorithm that allows us to ensure automated and consistent partitioning even for systems with delocalized and near-degenerate molecular orbitals and demonstrate the validity of this method for the binding energies of small molecules on transition-metal clusters.

Bottom-Up Short-Term Load Forecasting Considering Macro-Region and Weighting by Meteorological Region

Activities related to the planning and operation of power systems use premise load forecasting, which is responsible for providing a load estimative for a given horizon that assists mainly in the operation of an electrical system. Hierarchical short-term load forecasting (STLF) becomes an approach used for this purpose, where the overall forecast is performed through system partition in smaller macro-regions and, soon after, is aggregated to compose a global forecast. In this context, this paper presents a bottom-up STLF approach for macro-regions. The main innovation is the Average Consumption per Meteorological Region (CERM) index, used to weigh the importance of each station meteorological (EM) in total load demand. Another index, the Variation of Load and Temperature (IVCT), based on historical temperature and demand changes, is proposed. These indexes are incorporated into an ANN model of the multi-layer perceptron type (MLP). The results showed a higher average performance of the index CERM and variable IVCT in relation to the other combinations performed, and the best results were used to compose the prediction of the MTR. Finally, the proposed model presented a Mean Absolute Percentage Error lower than 1%, presenting superior performance compared to an aggregate model for MTR, which shows the efficiency and contribution of the proposed methodology.

EE-ONIOM-CT Method to Efficiently Account for the Missing Interactions in ONIOM: Energies and Analytic Gradients.

Hybrid methods such as ONIOM (QM:QM) are widely used for the study of local processes in large systems. However, the intrinsic need for system partitioning often leads to a less-than-desirable performance for some important chemical processes. This is due to the missing interactions in the chemically important model region (i.e., active site) of the high-level theory. The missing interactions can be categorized into two classes, viz. charge transfer (i.e., charge redistribution) and long-range electrostatic interactions. Our group presented two entirely different methods to treat these deficiencies individually. ONIOM-CT and ONIOM-EE methods have been demonstrated to improve the performance of ONIOM by incorporating charge transfer and missing electrostatic interactions, respectively. In general, the inclusion of the missing interactions separately in two different calculations may not be sufficient to reach a high accuracy. Thus, it is highly desirable to develop a method to correct both deficiencies simultaneously. In this work, we aim to connect the methods ONIOM-CT and ONIOM-EE for a more comprehensive treatment. A "stepwise" model was found to be necessary for a robust performance. This model employs a stepwise procedure by first satisfying the ONIOM-CT condition for charge balance before accounting for the electrostatic interactions from the rest of the system perturbatively. This has the advantage of easy interpretation due to the clear separation of the two effects. We demonstrate the performance of our method using embedding charges determined from a Mulliken population analysis. An efficient analytic gradient expression for this method is derived and implemented by requiring three sets of z-vector self-consistent equations. The performance of our method is assessed against full system calculations in high-level theory for a set of three proton transfer reactions representing different degrees of electrostatic embedding.

Asset Partitioning in Roman Law

This article describes results of analysis of the problem of asset partitioning in Roman law. Under asset partitioning the author understands the legal technique, which consists in giving property or part of it a special legal regime, which usually manifests in the relationship with creditors (the division of property into pools of assets available to different creditors), but may also manifest outside of the relationship with creditors.&#x0D; Various forms of asset partitioning are analyzed on the example of the following institutions of Roman law: dowry, peculium, lying inheritance, fiscal, societas publicanorum, property of municipalities, property of partnerships and families, common property. The author analyses the economic and socio-political reasons for the asset partitioning in Roman law, as well as the legal constructions by which it occurred. The article compares the legal institutions of Roman law related to asset partitioning with the institutions of modern law in Russia. The article also explores the question of the relationship of property separation with more studied and widespread legal structures (legal entity and retroactive force). Particular attention is paid to the problem of a legal entity (fictitious person) in Roman law in the context of the issue of asset partitioning and limited liability.&#x0D; The article shows the influence of Roman law on the existing legal systems and provides modern examples of the use of legal asset partitioning in foreign legal systems. The author substantiates the prospects of research and use of asset partitioning as an independent legal technique.

Impact of gate-level clustering on automated system partitioning of 3D-ICs

When partitioning gate-level netlists using graphs, it is beneficial to cluster gates to reduce the order of the graph and preserve some characteristics of the circuit that the partitioning might degrade. Gate clustering is even more important for netlist partitioning targeting 3D system integration. In this paper, we make the argument that the choice of clustering method for 3D-ICs partitioning is not trivial and deserves careful consideration. To support our claim, we implemented three clustering methods that were used prior to partitioning two synthetic designs representing two extremes of the circuits medium/long interconnect diversity spectrum. Automatically partitioned netlists are then placed and routed in 3D to compare the impact of clustering methods on several metrics. From our experiments, we see that the clustering method indeed has a different impact depending on the design considered and that a circuit-blind, universal partitioning method is not the way to go, with wire-length savings of up to 31%, total power of up to 22%, and effective frequency of up to 15% compared to other methods. Furthermore, we highlight that 3D-ICs open new opportunities to design systems with a denser interconnect, drastically reducing the design utilization of circuits that would not be considered viable in 2D.

Partitioning of distribution system into resilient clustered microgrids using complex network approach

Partitioning of distribution system into resilient clustered microgrids using complex network approach