Mechanical Control of Periodic Precipitation in Stretchable Gels to Retrieve Information on Elastic Deformation and for the Complex Patterning of Matter

Material design using nonequilibrium systems provides straightforward access to complexity levels that are possible through dynamic processes. Pattern formation through nonequilibrium processes and reaction–diffusion can be used to achieve this goal. Liesegang patterns (LPs) are a kind of periodic precipitation patterns formed through reaction–diffusion. So far, it has been shown that the periodic band structure of LPs and the geometry of the pattern can be controlled by experimental conditions and external fields (e.g., electrical or magnetic). However, there are no examples of these systems being used to retrieve information about the changes in the environment as they form, and there are no studies making use of these patterns for complex material preparation. This work shows the formation of LPs by a diffusion–precipitation reaction in a stretchable hydrogel and the control of the obtained patterns by the unprecedented and uncommon method of mechanical input. Additionally, how to use this protocol and how deviations from “LP behavior” of the patterns can be used to “write and store” information about the time, duration, extent, and direction of gel deformation are presented. Finally, an example of using complex patterning to deposit polypyrrole by using precipitation patterns is shown as a template.     

Managing ethical requirements elicitation of complex socio-technical systems with critical systems thinking: A case of course-timetabling project

Complex socio-technical systems pose considerable challenges to requirements elicitation due to dynamic boundary conditions and conflicting perspectives. Traditional requirements engineering is criticized for its failure in providing a systemic view, overlooking ethical concerns and marginalized social perspectives. It is argued that educational institutions as a part of society need to ethically develop and manage their academic processes and consider such perspectives for emancipation. This critical qualitative research applies the emancipatory systemic methodology of critical systems thinking (CST) for the requirements elicitation of a complex and dynamic university course-timetables management problem. Firstly, the problem is ethically formulated to mitigate Type III errors. Secondly, multiple viewpoints are sought for boundary judgments using a CST-based ethical inquiry of boundary critique to reveal the normative content of the project design, explore imbalances amongst the socio-technical design components, and unveil the underlying ethical issues. The dynamic stakeholder network captures the system's emergence through stakeholder interconnectedness and boundary liquidity by sweeping-in relevant stakeholders through the continuum of various states of the project. This work enlightens requirements engineering by coupling systemic and socio-technical lenses for the elicitation of ethical requirements and the emancipation of marginalized perspectives in complex and dynamic information systems projects in general and timetabling problems, in particular.     

Systems level approach reveals the correlation of endoderm differentiation of mouse embryonic stem cells with specific microstructural cues of fibrin gels

Stem cells receive numerous cues from their associated substrate that help to govern their behaviour. However, identification of influential substrate characteristics poses difficulties because of their complex nature. In this study, we developed an integrated experimental and systems level modelling approach to investigate and identify specific substrate features influencing differentiation of mouse embryonic stem cells (mESCs) on a model fibrous substrate, fibrin. We synthesized a range of fibrin gels by varying fibrinogen and thrombin concentrations, which led to a range of substrate stiffness and microstructure. mESCs were cultured on each of these gels, and characterization of the differentiated cells revealed a strong influence of substrate modulation on gene expression patterning. To identify specific substrate features influencing differentiation, the substrate microstructure was quantified by image analysis and correlated with stem cell gene expression patterns using a statistical model. Significant correlations were observed between differentiation and microstructure features, specifically fibre alignment. Furthermore, this relationship occurred in a lineage-specific manner towards endoderm. This systems level approach allows for identification of specific substrate features from a complex material which are influential to cellular behaviour. Such analysis may be effective in guiding the design of scaffolds with specific properties for tissue engineering applications.     

Implementation of Industry 4.0 and lean production in Brazilian manufacturing companies

The adoption of Industry 4.0 technologies has been deemed as a strategy to increase product quality and make manufacturing processes more efficient. However, the way that these technologies are integrated into existing production systems and which processes they can support is still under investigation. Thus, this paper aims to examine the relationship between lean production (LP) practices and the implementation of Industry 4.0 in Brazilian manufacturing companies. To achieve that we use data from a survey carried out with 110 companies of different sizes and sectors, at different stages of LP implementation. Data collected were analysed by means of multivariate analysis. Our findings indicate that LP practices are positively associated with Industry 4.0 technologies and their concurrent implementation leads to larger performance improvements. Further, the contextual variables investigated do matter to this association, although not all aspects matter to the same extent and effect.     

Leaky-mode loss of the second propagating mode in single-mode fibers with index well profiles

Radiation loss characteristics are calculated for the first two LP modes of a double-clad lightguide structure in which the inner cladding forms a low refractive-index well between the core and the outer cladding. The higher-order mode is defined to be effectively cut off at wavelengths where the LP(11) mode power is sufficiently attenuated to ensure negligible modal noise due to interference between LP(01) and LP(11) modes. Calculations apply for various deposited cladding thicknesses and findings can be easily extrapolated if specifications are changed for system requirements on the minimum unspliced fiber length or the extinction ratio between P(11) and P(01) mode powers, Re = 10 log P(11)/P(01). The latter is specified at points such as splice joints where modal noise is generated. Theoretical results are correlated with measurements in order to determine the effective cutoff wavelength for fibers in which leaky-mode loss mechanisms dominate. The procedure should be extremely useful for determining the shortest usable wavelength for single-mode lightwave systems.     

Failure time distributions for complex equipment

The exponential distribution is inadequate as a failure time model for most components; however, under certain conditions (in particular, that component failure rates are small and mutually independent, and failed components are immediately replaced or perfectly repaired), it is applicable to complex repairable systems with large numbers of components in series, regardless of component distributions, as shown by Drenick in 1960. This result implies that system behavior may become simpler as more components are added. We review necessary conditions for the result and present some simulation studies to assess how well it holds in systems with finite numbers of components. We also note that Drenick's result is analogous to similar results in other systems disciplines, again resulting in simpler behavior as the number of entities in the system increases.     

Biphasic responses in multi-site phosphorylation systems

Multi-site phosphorylation systems are repeatedly encountered in cellular biology and multi-site modification is a basic building block of post-translational modification. In this paper, we demonstrate how distributive multi-site modification mechanisms by a single kinase/phosphatase pair can lead to biphasic/partial biphasic dose–response characteristics for the maximally phosphorylated substrate at steady state. We use simulations and analysis to uncover a hidden competing effect which is responsible for this and analyse how it may be accentuated. We build on this to analyse different variants of multi-site phosphorylation mechanisms showing that some mechanisms are intrinsically not capable of displaying this behaviour. This provides both a consolidated understanding of how and under what conditions biphasic responses are obtained in multi-site phosphorylation and a basis for discriminating between different mechanisms based on this. We also demonstrate how this behaviour may be combined with other behaviour such as threshold and bistable responses, demonstrating the capacity of multi-site phosphorylation systems to act as complex molecular signal processors.     

A primary influence vertex approach to identify driving factors in complex integrated agri-industrial systems – an example from sugarcane supply and processing systems

Integrated agri-industrial systems (IAISs), such as sugarcane supply and processing systems, are complex systems and hence generally difficult to understand and manage. The large number factors in IAISs coupled with the complex interrelationships among the factors make it challenging to identify the points of intervention for improving their overall performance. Several approaches, such as the network theory and the Theory of Constraints have been used to identify important factors in systems with variations in success. This paper demonstrates a primary influence vertex approach for identifying and ranking the factors that drive the performance of IAISs. The approach is based on comprehensive causal network analyses and was tested in four relatively diverse large-scale sugarcane milling operations in South Africa. Results from the analyses were found to be consistent with the literature and external knowledge of the milling areas as at the time of the study. It is concluded that the approach can proffer a sound basis from which deeper rooted problems in systems can be identified on an ongoing basis. It is, however, recommended that the approach should be systematically compared with other relevant methods that are used to analyse complex systems.     

Production system redesign using realistic visualisation

The process of redesigning production systems is usually complex, for which virtual design tools are available. These tools are used to analyse and evaluate planned changes prior to implementation, making it possible to identify and prevent costly design mistakes. Despite this, design mistakes arise during and after the implementation. A source for design mistakes is incorrect or insufficient spatial data of the production systems used in the virtual design tools. The aim of this paper is to show how to reduce the time required for planning and implementing the redesign by supporting the process with realistic visualisation, created from accurate spatial data of the real production systems. Three industrial studies were carried out to evaluate how address realistic visualisation in order to support the redesign process. The result shows terrestrial 3D laser scanning to be suitable for capturing spatial data for realistic visualisation of production systems. The realistic visualisation can be used to virtually analyse design alternatives of the production systems, by, for example, combining the 3D laser scan data with 3D CAD models. The realistic visualisation enabling effective and accurate planning, which gives the opportunity to reduce the time required for planning and implementing redesigned production systems.     

Dynamic risk assessment of complex systems using FCM

Analysing risk of today’s complex systems is challenging due to the complex and dynamic nature of systems. The current risk analysis tools are not able to take the complex interactions among risks into account and therefore they can’t predict the behaviour of risks accurately. In an attempt to overcome this shortcoming, this paper proposes an integrated generalised decision support tool using fuzzy cognitive maps for dynamic risk assessment of complex systems. The proposed approach has the ability to prioritise risk factors and more importantly predict and analysis the influences of each individual risk factor/risk set on the other risks or on the outcomes of complex and critical systems by taking into account probability of occurrence and consequences of risks and also considering the complex dependencies between risk factors. These features could provide practitioners with realistic results in critical industries and able them to manage risks more efficiently.     

Learning organisation and lean production: an empirical research on their relationship

This study aims at identifying the pairwise relationship between specific sets of Lean Production (LP) practices and Learning Organisation (LO) dimensions. More specifically, the association between 10 LP operational constructs and seven LO dimensions, based upon previous literature, is empirically examined. A survey-based study was carried out with 135 companies undergoing a LP implementation. The study sample was categorised according to two control variables: type of organisation and company’s LP implementation experience. Collected data was analysed through multivariate techniques. Results indicate that LP implementation and LO development are highly correlated. Additionally, findings also show that the extent of relationships varies according to the context, allowing the identification of synergistic associations and conflicting ones. The identification of these relationships provides means to better comprehend how the implementation of specific LP practices corroborates to enhancing LO capabilities within the organisation and vice-versa.     

Performance measurement and management: a system of systems perspective

Despite changes in tools and practices, the conceptual foundations of performance measurement and management (PMM) are still predominantly rooted in control systems research. While PMM approaches have delivered significant organisational benefits, including creating alignment, supporting monitoring and control, and enabling prediction and optimisation of resource allocation, this paper argues that this paradigm is not capable of responding to increasingly complex and highly uncertain organisational environments. Drawing on ideas emerging in the literature on systems engineering and complex systems, we propose a novel perspective that considers PMM from a ‘system of systems’ (SoS) point of view, whose essential characteristics are autonomy, belonging, connectivity, diversity and emergence. After identifying the assumptions underpinning existing PMM approaches, we outline a SoS-based paradigm to PMM and conclude by articulating the main implications for the practice of PMM and setting out a research agenda.     

液阻悬置惯性通道阻尼特性的实验与计算分析

以一轿车动力总成惯性通道型液阻悬置为研究对象,讨论了线性与非线性集总参数模型和模型中物理参数的特点及应用范围;应用流体力学有限元分析的方法,计算得到了惯性通道两端压力差与其中液体流动流量的关系,设计并制作了实验台,对计算结果进行了验证.利用惯性通道中液体流动的动量方程和惯性通道两端的压力差与其流量的关系,采用最小二乘方法,得到了惯性通道中液体流动的阻尼参数.该方法得到的阻尼参数,在较大激振频率和激振振幅范围内反应了惯性通道的阻尼特性.利用非线性的集总参数模型和本文方法得到的惯性通道阻尼特性参数,对一液阻悬置的动态特性进行了计算分析,计算结果和实验结果具有较好的一致性.     

Microemulsion systems containing bioactive natural oils: an overview on the state of the art

Abstract

Natural oils are extremely complex mixtures containing compounds of different chemical nature. Some of them have physiological or therapeutic activities that may act either alone or in synergy. Therefore, they are used in the pharmaceutical, agronomic, food, sanitary and cosmetic industries. Today, the interest in bioactive natural oils is growing due to their immense potential to prevent and treat numerous human diseases. Formulation in microemulsions (MEs) containing natural oils appeared suitable to improve pharmaceutical and biopharmaceutical properties of bioactive compound derivatives from these oils. Microemulsion systems are thermodynamically stable, transparent, and are isotropic dispersions consisting of oil and water stabilized by an interfacial film of surfactants, typically in combination with a cosurfactant. They can protect labile compounds from premature degradation, control release, increase solubility and hence enhance the bioavailability of poorly bioavailable compounds. The aim of this work was to review the various advantages of bioactive compounds presented in natural oil loaded ME systems to be used as delivery systems. First, the state of the art of the parameters involved in the ME formation, including the basic concepts of the physicochemical formulation of the ME systems, and the main aspects of production and the energy responsible for their formation were reported. The second section describes the use of ME systems and reviews the recent applications of natural oil-loaded in the ME systems as the bioactive compound in the formulation.     

Assessment of low probability events of dynamical systems by controlled Monte Carlo simulation

Various procedures to extend the applicability and to increase the efficiency of Monte Carlo simulation (MCS) for the analysis of complex dynamical systems are discussed. In particular, the capabilities of the methods denoted Russian Roulette and Splitting (RR&S) and Double and Clump (D&C) are reviewed with regard to their capabilities to analyze such systems. In this context, the difficulties in identifying the ‘important' regions for simulation are detailed. It is shown that these difficulties may be circumvented by a newly introduced ‘distance controlled' MCS. This procedure, which allows the prediction of very low probability events and the analysis of systems of higher dimension, is applicable not only to mechanical systems and structures but also to complex dynamical systems encountered, for example, in economics, physics, etc. The procedure is shown to be particularly suited to cases where exact analytical methods and direct Monte Carlo simulation are infeasible, hence, being well suited for practical application.     

A case study on the use of data mining for detecting and classifying abnormal power system modal behaviors

This article presents a case study involving data mining (DM) and the knowledge discovery (KD) process for the Western US power grid. With the installation of phasor measurement units (PMUs) in the US power systems, there is potential to improve wide-area situational awareness using data analytics. The KD process is challenging due to the complex nature of the power grid, data propriety issues, the file size of the time-series data, and questions of how to extract meaningful features. This case study demonstrates how the KD process can be implemented in light of these challenges to detect the anomalies of interest.     

Stochastic amplification in epidemics

The role of stochasticity and its interplay with nonlinearity are central current issues in studies of the complex population patterns observed in nature, including the pronounced oscillations of wildlife and infectious diseases. The dynamics of childhood diseases have provided influential case studies to develop and test mathematical models with practical application to epidemiology, but are also of general relevance to the central question of whether simple nonlinear systems can explain and predict the complex temporal and spatial patterns observed in nature outside laboratory conditions. Here, we present a stochastic theory for the major dynamical transitions in epidemics from regular to irregular cycles, which relies on the discrete nature of disease transmission and low spatial coupling. The full spectrum of stochastic fluctuations is derived analytically to show how the amplification of noise varies across these transitions. The changes in noise amplification and coherence appear robust to seasonal forcing, questioning the role of seasonality and its interplay with deterministic components of epidemiological models. Childhood diseases are shown to fall into regions of parameter space of high noise amplification. This type of "endogenous" stochastic resonance may be relevant to population oscillations in nonlinear ecological systems in general.     

A CAD-based tool for development of large layouts

This paper focuses on the development of a CAD-based tool for the design of complex systems layout, where the primary objective is to compress time to market. We describe the concept for a library which contains necessary information for the conceptual stage of the design process based on the features technology. The stored information has both geometric and non-geometric characteristics. Geometric information is the core of the CAD-based tool. It is in the form of a geometry library which contains systematically abstracted 3-D CAD models. We introduce guidelines for geometric abstraction so that large layouts can be constructed and analysed in 3-D CAD systems. Besides a simplified version of the virtual model of a product, non-geometric information such as functionality, mode of action, costs, material properties, etc., are provided. The method described has been applied for the design of complex train equipment. The results reveal that the lead time required to develop an equipment layout is reduced to about 70 compared with early designs.     

On Cost‐effective Reuse of Components in the Design of Complex Reconfigurable Systems

Design strategies that benefit from the reuse of system components can reduce costs while maintaining or increasing dependability—we use the term dependability to tie together reliability and availability. D3H2 (aDaptive Dependable Design for systems with Homogeneous and Heterogeneous redundancies) is a methodology that supports the design of complex systems with a focus on reconfiguration and component reuse. D3H2 systematizes the identification of heterogeneous redundancies and optimizes the design of fault detection and reconfiguration mechanisms, by enabling the analysis of design alternatives with respect to dependability and cost. In this paper, we extend D3H2 for application to repairable systems. The method is extended with analysis capabilities allowing dependability assessment of complex reconfigurable systems. Analysed scenarios include time‐dependencies between failure events and the corresponding reconfiguration actions. We demonstrate how D3H2 can support decisions about fault detection and reconfiguration that seek to improve dependability while reducing costs via application to a realistic railway case study. Copyright © 2017 John Wiley & Sons, Ltd.     

纵向变厚度(LP)矩形钢板弹性屈曲系数的理论分析

纵向变厚度(LP)钢板因适应现代化建筑超高层及大跨度的发展使用需求,将广泛应用于工程结构中。因LP钢板几何形状的特殊性,其局部屈曲变形更容易发生在靠近薄端的位置,并且钢板局部稳定性能与相同受力状态下的等厚度钢板差异较大,需要进行深入研究。基于能量原理,采用Galerkin和Rayleigh-Ritz法(GRM),对单向均匀受压荷载作用下四种不同边界条件下的矩形LP钢板的弹性屈曲系数的计算公式进行了理论推导,并采用ANSYS有限元软件验证了公式的正确性。最后得到了不同厚度放大系数下,四种边界条件下的矩形钢板的弹性屈曲系数与钢板长宽比的关系曲线图,进一步为LP钢板的工程应用提供理论指导和设计依据。