Constituent Systems Research Articles

Multiple Frequencies in the Basal Ganglia in Parkinson's Disease

In recent years, the authors have developed what appears to be a very successful phenomenological model for analyzing the role of deep brain stimulation (DBS) in alleviating the symptoms of Parkinson's disease. In this paper, we extend the scope of the model by using it to predict the generation of new frequencies from networks tuned to a specific frequency, or indeed not self-oscillatory at all. We have discussed two principal cases: firstly where the constituent systems are coupled in an excitatory-excitatory fashion, which we designate by ``+/+''; and secondly where the constituent systems are coupled in an excitatory-inhibitory fashion, which we designate ``+/-''. The model predicts that from a basic system tuned to tremor frequency we can generate an unlimited range of frequencies. We illustrate in particular, starting from systems which are initially non-oscillatory, that when the coupling coefficient exceeds a certain value, the system begins to oscillate at an amplitude which increases with the coupling strength. Another very interesting feature, which has been shown by colleagues of ours to arise through the coupling of complicated networks based on the physiology of the basal ganglia, can be illustrated by the root locus method which shows that increasing and decreasing frequencies of oscillation, existing simultaneously, have the property that their geometric mean remains substantially constant as the coupling strength is varied. We feel that with the present approach, we have provided another tool for understanding the existence and interaction of pathological oscillations which underlie, not only Parkinson's disease, but other conditions such as Tourette's syndrome, depression and epilepsy.

Investigations of quaternary interdiffusion in a constituent system of high entropy alloys

Interdiffusion was investigated at 1000°C in a quaternary Fe-Ni-Co-Cr system, which is an essential constituent of many high-entropy alloys. The relative values of main and cross interdiffusion coefficients determined from concentrations and interdiffusion fluxes developed in a single diffusion couple indicate that significant diffusional interactions exist in this system. Thermodynamic interactions between the binary constituents were analyzed based on the activity coefficient relations and it is shown that the observed diffusional interactions of a component with others are consistent with relative thermodynamic interactions between them.

Snake venoms are integrated systems, but abundant venom proteins evolve more rapidly.

BackgroundWhile many studies have shown that extracellular proteins evolve rapidly, how selection acts on them remains poorly understood. We used snake venoms to understand the interaction between ecology, expression level, and evolutionary rate in secreted protein systems. Venomous snakes employ well-integrated systems of proteins and organic constituents to immobilize prey. Venoms are generally optimized to subdue preferred prey more effectively than non-prey, and many venom protein families manifest positive selection and rapid gene family diversification. Although previous studies have illuminated how individual venom protein families evolve, how selection acts on venoms as integrated systems, is unknown.ResultsUsing next-generation transcriptome sequencing and mass spectrometry, we examined microevolution in two pitvipers, allopatrically separated for at least 1.6 million years, and their hybrids. Transcriptomes of parental species had generally similar compositions in regard to protein families, but for a given protein family, the homologs present and concentrations thereof sometimes differed dramatically. For instance, a phospholipase A2 transcript comprising 73.4 % of the Protobothrops elegans transcriptome, was barely present in the P. flavoviridis transcriptome (<0.05 %). Hybrids produced most proteins found in both parental venoms. Protein evolutionary rates were positively correlated with transcriptomic and proteomic abundances, and the most abundant proteins showed positive selection. This pattern holds with the addition of four other published crotaline transcriptomes, from two more genera, and also for the recently published king cobra genome, suggesting that rapid evolution of abundant proteins may be generally true for snake venoms. Looking more broadly at Protobothrops, we show that rapid evolution of the most abundant components is due to positive selection, suggesting an interplay between abundance and adaptation.ConclusionsGiven log-scale differences in toxin abundance, which are likely correlated with biosynthetic costs, we hypothesize that as a result of natural selection, snakes optimize return on energetic investment by producing more of venom proteins that increase their fitness. Natural selection then acts on the additive genetic variance of these components, in proportion to their contributions to overall fitness. Adaptive evolution of venoms may occur most rapidly through changes in expression levels that alter fitness contributions, and thus the strength of selection acting on specific secretome components.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1832-6) contains supplementary material, which is available to authorized users.

Stabilization of Switched Linear Differential Algebraic Equations and Periodic Switching

We investigate the stabilizability of switched linear systems of differential-algebraic equations (DAEs). For such systems we introduce a parameterized family of switched ordinary differential equations that approximate the dynamic behavior of the switched DAE. A necessary and sufficient criterion for the stabilizability of a switched DAE system using time-dependent switching is obtained in terms of these parameterized approximations. Furthermore, we provide conditions for the stabilizability of switched DAEs via fast switching as well as using solely the consistency projectors of the constituent systems. The stabilization of switched DAEs with commuting vector fields is also analyzed.

Governing Singapore

Purpose – The purpose of this paper is to examine the impact of the Group Representation Constituency (GRC) system on the governance of Singapore, particularly in terms of equity and inclusiveness, accountability, and participation. Design/methodology/approach – Historical review and election data from Singapore government web site are used. Findings – The GRC system seems to be friendlier and fairer toward ethnic minorities than the traditional system. The GRC system also encourages political parties to be ethnically more inclusive. On the other hand, however, the GRC system has negative effects on opposition parties. A government cannot be called “accountable” if it lacks fair competition and sufficient popular participation. Originality/value – The Singapore experience shows that, in practice, ethnic equality/inclusiveness and even political stability on the one hand, and participation and accountability on the other hand, can present conflicts. Which value should receive priority thus requires serious consideration.

The Restriction of Topic's Relativization and Structuring Theme

In this paper, it is argued that the NP is not a pragmatic topic. Only the topic derived from the assigned case in the clause can be relativized. The first subject of double subjective clause in Korean become the topic of the sentence, while it is not assigned theta-role by the verb, but a pragmatic topic(PT) of level of coversation is not eligible for relativization. The first subject as a topic in double subjective clause is checked the abstract determiner by predicative system of other constituents in a hole sentence, because the determiner is defined by predicative system in Korean sentence. PT is not defined by construction of the clause.:It is a constituent of pragmatic context. In this article, topic with a syntactic property is argued as one of the ``Theme``, while PT cannot be Theme.

The Cr–Fe–Nb ternary system: Experimental isothermal sections at 700 °C, 1050 °C and 1350 °C

The Cr–Fe–Nb system is an important constituent system in the development of Laves-phase reinforced steels. It contains two Laves-phase polytypes, i.e. C14–Fe2Nb and C15–Cr2Nb. While the first forms a substantial ternary solid solution with Cr, the latter only shows a limited solubility for Fe. The phase equilibria in the Cr–Fe–Nb system are shown in three isothermal sections at 700, 1050 and 1350 °C. Scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX), X-ray diffraction (XRD) and electron back scatter diffraction (EBSD) were used to determine the phase equilibria from which the isothermal sections were constructed.

Liquidus projection of Cu–In–Se photovoltaic material system

Cu–In–Se (CIS) and its based alloys are among the most important solar cell materials. However, there are only limited Cu–In–Se phase equilibria data available. This study determines the liquidus projection of the Cu–In–Se system. Cu–In–Se alloys were prepared from pure constituent elements. The primary solidification phases of as-cast Cu–In–Se alloys were determined. The univariant lines of Cu–In–Se liquidus projection were constructed according to the experimental results determined in this study, those in the literature and the phase diagrams of its three binary constituent systems. There are 15 primary solidification phases in the ternary Cu–In–Se liquidus projection: β1-Cu2Se, Cu, β2-Cu4In, γ-Cu7In3, η′-Cu2In, Cu11In9, In, In4Se3, InSe, In6Se7, In2Se3, Se, CuSe2, CuSe and CuInSe2 phases. A large miscibility gap extends from the Cu–Se side to the In–Se side. There are 16 ternary invariant reactions in this Cu–In–Se liquidus projection involved in the liquid phase. The temperatures of invariant reactions were determined using differential thermal analysis.

Incentive‐Based Negotiation Model for System of Systems Acquisition

ABSTRACTLack of collaboration between individual systems and system of systems (SoS) program management is identified as one of the leading problems in SoS acquisition. This is especially a major concern in acknowledged SoS where a designated SoS program management has no authority over the constituent systems. Therefore, it is important to consider mechanisms to persuade individual systems to participate in the SoS development. In SoS where individual systems have their own self‐interests, negotiation becomes an important mechanism to increase participation in SoS development. Another mechanism, incentives, is used in a wide range of applications to improve performance and collaboration. In this paper, an incentive based negotiation model is outlined as a mechanism to increase participation of individual systems into the SoS development. The negotiation model is integrated into an SoS Engineering and Architecting multilevel model referred to as Flexible &amp; Intelligent Learning Architectures for SoS (FILA‐SoS). Various aspects of SoS acquisition are modeled in the FILA‐SoS including SoS meta‐architecture generation, evaluation as well as negotiation between SoS and individual systems. Individual systems exhibit behaviors, ranging from selfish to cooperative. The negotiation model is demonstrated on an SoS engineering application: Intelligence, Surveillance, and Reconnaissance (ISR) SoS acquisition case where a desired meta‐architecture is selected for negotiation, and incentives are determined for systems based on deviation from the desired meta‐architecture quality. The analyses of the results from this application domain provide insights into how incentives can be used by decision makers to increase participation in SoS engineering and development.

A Visual Formalism for Interacting Systems

Interacting systems are increasingly common. Many examples pervade our everyday lives: automobiles, aircraft, defense systems, telephone switching systems, financial systems, national governments, and so on. Closer to computer science, embedded systems and Systems of Systems are further examples of interacting systems. Common to all of these is that some "whole" is made up of constituent parts, and these parts interact with each other. By design, these interactions are intentional, but it is the unintended interactions that are problematic. The Systems of Systems literature uses the terms "constituent systems" and "constituents" to refer to systems that interact with each other. That practice is followed here. This paper presents a visual formalism, Swim Lane Event-Driven Petri Nets, that is proposed as a basis for Model-Based Testing (MBT) of interacting systems. In the absence of available tools, this model can only support the offline form of Model-Based Testing.

Liquidus projection and isothermal section at 650 °C of ternary Co–Sb–Ga system

Co–Sb–Ga ternary system is of interests for thermoelectric applications. Alloys quenched from completely molten state with compositions of the entire Co–Sb–Ga regime and alloys equilibrated at 650°C with compositions in the CoSb3–CoGa–Ga–Sb regime were prepared and analyzed. The liquidus projection and isothermal section at 650°C of ternary Co–Sb–Ga system were determined based on these experimental results and the phase diagrams of its three constituent binary systems. The liquidus projection has 10 primary solidification phase regions. They are Co, CoSb, CoSb2, CoSb3, Sb, GaSb, Ga, CoGa3, CoGa and a ternary compound, Co3Sb2Ga4, which is newly found. There are three class I and six class II invariant reactions involving with liquid phase. Except for the L↔Co+CoSb+CoGa, L+CoGa↔Co3Sb2Ga4+GaSb reaction, the reaction temperatures are determined using DTA. In the CoSb3–CoGa–Ga–Sb region, there are 5 tie-triangles, which are CoSb3+Liquid+GaSb, Co3Sb2Ga4+CoSb3+GaSb, CoGa+Co3Sb2Ga4+GaSb, CoGa+GaSb+CoGa3, and CoGa3+GaSb+Liquid. The ternary solubilities in most of the binary compounds are not significant, and the highest is 3.5at.% Sb in the CoGa.

Stabilizing Switching Signals for Switched Systems

This article deals with stability of continuous-time switched systems under constrained switching. Given a family of systems, possibly containing unstable dynamics, we characterize a new class of switching signals under which the switched system generated by it and the family of systems is globally asymptotically stable. Our characterization of such stabilizing switching signals involves the asymptotic frequency of switching, the asymptotic fraction of activation of the constituent systems, and the asymptotic densities of admissible transitions among them. Our techniques employ multiple Lyapunov-like functions, and extend preceding results both in scope and applicability.

System of Systems Approach to Formal Modeling of CPS for Simulation-Based Analysis

This paper presents a system-of-systems (SoS) approach to the formal modeling of a cyber-physical system (CPS) for simulation-based analysis. The approach is based on a convergence technology for modeling and simulation of a highly complex system in which SoS modeling methodology, hybrid systems modeling theory, and simulation interoperation technology are merged. The methodology maps each constituent system of a CPS to a disparate model of either continuous or discrete types. The theory employs two formalisms for modeling of the two model types with formal specification of interfaces between them. Finally, the technology adapts a simulation bus called DEVS BUS whose protocol synchronizes time and exchange messages between subsystems simulation. Benefits of the approach include reusability of simulation models and environments, and simulation-based analysis of subsystems of a CPS in an inter-relational manner.

Exploring a Timed-automata Fuzzy Cognitive Maps Based Approach for Modeling Systems of Systems

The need for effectively developing high quality solutions for very large scale, complex problems continues to drive research in modeling and analyzing System of Systems (SoS). These kinds of systems span numerous domains, including essential infrastructure (water, power, transportation, emergency response, healthcare, education, finance, military, environmental protection etc.). A SoS is composed of independent, autonomous constituent systems; the SoS provides emergent behavior that goes beyond the capabilities of its constituent systems. Having the capability to predict the emergent behavior would be very valuable in assessing the impact of changes in a constituent system's behavior on the emergent behavior of the SoS. For example, if a constituent system is being added, modified, or retired, how will this impact the SoS? In this paper, we explore a new approach to model a SoS, with a focus on emergent behavior for non-functional properties (e.g., safety, reliability etc.,). The approach is based on the visual, formal method Timed-Automata-Based Fuzzy Cognitive Maps (TA-FCMs). A published case study on a water treatment SoS for the Beijing Nanshahe River Basin is used in this work. In future work, we plan to refine our modeling approach and continue on with investigating approach to provide the predictive analysis and formal verification.

J1220102 自動車の自動運転システムに対する安全性要求のアシュアランスケースによる分析

This paper shows analysis of safety requirements for automated vehicles from System of Systems (SoS) perspective using SysML and assurance cases. Interactions among automated vehicles, other constituent systems and environments are very important for realization of the safety. The SoS architecture described with SysML are analyzed using assurance cases to derive the safety goals for each actor of constituent systems. Finally the safety requirements for automated system are derived and the relationships among the safety goals and constituent systems are shown.

The Top 10 Illusions of Systems Engineering: A Research Agenda

Traditional systems engineering is predicated upon prediction and control. Prediction is required to attain some degree of confidence that design and manufacture decisions will yield desired results. Control is necessary to ensure that subsystems meet the needs of the overarching system. While this paradigm was successful for decades, evolving circumstances have resulted in two challenges. First, the increasing complexity of systems has eroded the system engineer's ability to predict the outcome of his or her design decisions. Second, the need to interconnect existing systems in the form of a system of systems challenges the system engineer's ability to exercise technical control because of the operational and managerial independence of the constituent systems. The application of a process predicated on invalid assumptions is not likely to achieve desirable results. This paper presents the top 10 assumptions, which are often illusory in today's systems environment. Unfortunately, our current systems engineering practices are based on heuristics dependent on many of these assumptions, often in the context of aerospace and defense programs, that have been acquired during the past half century, rather than on a solid body of scientific knowledge and are inadequate to support the discipline's necessary transformation. Consequently, research is critical to create the foundations that can support a new paradigm for systems engineering, one that is based on the reality of engineering systems in which deterministic prediction and control are no longer possible in many circumstances.

Densities, surface tensions, and isobaric vapor–liquid equilibria for the mixtures of 2-propanol, water, and 1,2-propanediol

Densities and surface tensions of the ternary system (2-propanol+1,2-propanediol+water) at T=298.15K and its constituent binary systems (2-propanol+1,2-propanediol and 1,2-propanediol+water) at T=298.15, 308.15, 318.15, and 328.15K were measured under atmospheric pressure. Densities were determined using a vibrating-tube densimeter. Surface tensions were determined by the Wilhelmy-plate method. From the experimental binary and ternary data, the excess molar volumes and deviations in surface tension were calculated. These excess quantities were fitted to the Redlich–Kister equation, a simple equation based on Connors and Wright, and a modified equation of Cibulka, respectively. The results were used to study the nature of mixing behaviors between mixture components.Isobaric vapor–liquid equilibrium (VLE) at P=101.3kPa have been measured for the ternary system of 2-propanol+water+1,2-propanediol using an equilibrium still with circulation of both vapor and liquid phases. The effect of 1,2-propanediol on the VLE of 2-propanol+water was studied with three mass fractions (0.10, 0.30, and 0.50) of 1,2-propanediol in the overall liquid mixtures. The equilibrium compositions of mixtures were analyzed by gas–liquid chromatography. The results showed that the azeotropic point between 2-propanol and water can be eliminated when the mass fraction of 1,2-propanediol in the feed is up to 0.50. The relative volatilities of 2-propanol with respect to water were also determined. The new ternary VLE data were successfully correlated with the Wilson, NRTL, and UNIQUAC models, for which the binary interaction parameters are reported. The comparison of the volatility effect of 1,2-propanediol with that of 1,3-propanediol on 2-propanol+water was illustrated.

A new process for fuel ethanol dehydration based on modeling the phase equilibria of the anhydrous MgCl2 + ethanol + water system

The use of ethanol as a fuel for motor engines has attracted significant attention because of its possible environmental and economic advantages over fossil fuel. However, the energy demand for the ethanol dehydration process significantly impacts its production cost. A new and energy efficient process is developed on the basis of salt extractive distillation, which uses recycled MgCl2 granules as a separating agent. Vapor‐liquor‐equilibria (VLE) data for the ternary MgCl2 + ethanol + water system, and the three constituent binary systems were measured at 30, 60, 90, and 101.3 kPa. A large enhancement of relative volatility of the ethanol + water system in the presence of MgCl2 is observed throughout the entire ethanol concentration range, which completely broke the azeotrope. The salt effect of MgCl2 is thought to be the result of energetic interactions and the hydration equilibrium reaction of the Mg2+ ion with water molecules. The calculation results by the mixed‐solvent electrolyte model embedded in the OLI platform equipped with new model interaction parameters and equilibrium constant (obtained via the regression of experimental VLE data), provided for a satisfactory means of simulating the MgCl2 salt extractive distillation process. Finally, the process was proven feasible at the laboratory‐scale resulting in large granules of recovered MgCl2 and a product of 99.5 wt % ethanol. © 2014 American Institute of Chemical Engineers AIChE J, 61: 664–676, 2015

Experimental Determination and Thermodynamic Modeling of the Sn-Rich Corner of the Ternary Ni-Pd-Sn Phase Diagram at 250°C

The Sn-rich portion of the phase diagram for the Ni-Pd-Sn ternary system was preliminarily obtained by interpolation of the three constituent binary systems using the Muggianu method. Based on this proposition, 23 Ni-Pd-Sn alloys were prepared and annealed at 250°C. The annealed alloys were analyzed by scanning electron microscopy, electron probe microanalysis, electron backscatter diffraction, and x-ray diffraction. All the binaries adjacent to the Sn-rich corner (i.e., PdSn4, PdSn3, PdSn2, and Ni3Sn4) were found to have remarkable ternary solubility. The experimental results presented herein, together with a thermodynamic interpolation of the ternary system based on the results from the binary systems, were used to calculate the ternary phase diagram using the calculation of phase diagrams (CALPHAD) method. A substitution model was used to describe the Gibbs free energies of the liquid and solid solution phases, and a sublattice model was used to describe intermetallic compounds. A consistent set of thermodynamic parameters was obtained, ultimately leading to a better fit between the calculated results and the experimental data for this system.

Cascading effects in interdependent networks

Modern systems are increasingly dependent upon and interacting with each other, and become interdependent networks. These interdependent networks may exhibit some interesting and even surprising behaviors due to the interdependency and the interplay between the constituent systems. In this article we focus on two important phenomena, namely cascading failure in cyber-physical systems (CPS) and information cascade in coupled social networks. Specifically, cascading failures may occur in CPS that exhibit functional interdependency between two constituent systems (e.g. smart grid); information cascade may happen in multiple social networks that are coupled together by so-called multi-membership individuals. This article explores these two types of cascading effects in interdependent networks by reviewing existing studies in the literature. We review different models in the literature to study the two types of cascading effects in interdependent networks, and highlight the key findings from these studies.