Robust decision making for agile systems development Part 2: a decomposition and analysis

The need for agility in operational systems within the defence enterprise and procurement domains has been identified by many authors, and over time, there have been a number of initiatives and programmes that have sought to identify the nature of agility, and the means by which it can be defined and employed within individual cases and scenarios. These have identified impediments to the successful realization of agile practices and methods, particularly the resilience of agile decision making throughout the conceptual understanding, design and implementation of the operational system. To further investigate the extent to which this process can be implemented in a robust and reliable manner, Cranfield University created the ‘Robust Enterprise-based Approach for Agility in Capability Through-life (REA2CT)’ framework, which provides a number of functional steps to institute a systems development lifecycle approach to producing agile solutions for use in networked systems and systems-of-systems. This paper builds upon the description of the framework[1] by applying the Axiomatic Design (AD) theory to identify where complexity exists within the requirements and design activities that underpin the framework. Using this analysis, this paper identifies ‘pain points’ within the REA2CT framework, and suggests necessary improvements to facilitate the implementation of agility throughout the systems development lifecycle

Robust decision making for agile systems development Part 1: exploring the paradigm

The need for agility in operational systems within the defence enterprise and procurement domains has been identified by many authors, and over time, there have been a number of initiatives and programmes that have sought to identify the nature of agility, and the means by which it can be defined and employed within individual cases and scenarios. These have identified impediments to the successful realization of agile practices and methods, particularly the resilience of agile decision making throughout the conceptual understanding, design and implementation of the operational system. To further investigate the extent to which this process can be implemented in a robust and reliable manner, Cranfield University created the ‘Robust Enterprise-based Approach for Agility in Capability Through-life (REA2CT)’ framework, which provides a number of functional steps to institute a systems development lifecycle approach to producing agile solutions for use in networked systems and systems-of-systems. This paper briefly examines the Customer Need (CN) for the enterprise-based delivery of system (of systems) agility into the operational domain. Axiomatic Design (AD) theory is used to describe the REA2CT framework, identifying Functional Requirements (FRs) which might satisfy the CN for agility. Initial Design Parameters (DPs) are proposed to satisfy the FRs

On the resilience of systems of systems

The need to consider how systems can be made resilient to failure modes has gained increasing traction in the fields of systems thinking and systems design, and is now more widely studied, with authors identifying the potential disruptive effects of failure upon a system, and codifying these disruptions into specific types. When the focus of specification moves from the bounded single system to the consideration of capability and effect, systems-of-systems, rather than systems must be contended with. Systems-of-systems have been classified as being of a number of types (acknowledged, collaborative, directed, virtual, for example), whilst authors have endeavoured to characterise the properties of systems-of-systems, and the difficulties associated with their design, introduction and operation. This study has invariably arrived at the conclusion that systems-of-systems are infinitely more complex than bounded single systems, and as the final system-of-systems design will still need to be resilient to failure, this in turn poses more difficult questions for the study of resilience, as the properties of a bounded single system are unlikely to be the same as those of a system-of-systems. This paper will consider the problems faced by the need to specify resilience in a system-of-systems environment, by first evaluating how the various types and properties of systems-of-systems might affect the consideration of resilience, and then proposes an initial codification of systems-of-systems resilience disruption types, along with recommendations and required further work

Prevalence of disorders recorded in Cavalier King Charles Spaniels attending primary-care veterinary practices in England

Concerns have been raised over breed-related health issues in purebred dogs, but reliable prevalence estimates for disorders within specific breeds are sparse. Electronically stored patient health records from primary-care practice are emerging as a useful source of epidemiological data in companion animals. This study used large volumes of health data from UK primary-care practices participating in the VetCompass animal health surveillance project to evaluate in detail the disorders diagnosed in a random selection of over 50% of dogs recorded as Cavalier King Charles Spaniels (CKCSs). Confirmation of breed using available microchip and Kennel Club (KC) registration data was attempted

Ionization state, excited populations and emission of impurities in dynamic finite density plasmas: I. The generalized collisional-radiative model for light elements

The paper presents an integrated view of the population structure and its role in establishing the ionization state of light elements in dynamic, finite density, laboratory and astrophysical plasmas. There are four main issues, the generalized collisional-radiative picture for metastables in dynamic plasmas with Maxwellian free electrons and its particularizing to light elements, the methods of bundling and projection for manipulating the population equations, the systematic production/use of state selective fundamental collision data in the metastable resolved picture to all levels for collisonal-radiative modelling and the delivery of appropriate derived coefficients for experiment analysis. The ions of carbon, oxygen and neon are used in illustration. The practical implementation of the methods described here is part of the ADAS Project

THE PHENOLOGY AND DISTRIBUTION OF APHIDS IN CALIFORNIA ALFALFA AS MODIFIED BY LADYBIRD BEETLE PREDATION (COLEOPTERA: COCCINELLIDAE)

The phenologies and distributions of pea aphid (Acyrthosiphon pisum (Harris)), blue alfalfa aphid (A. kondoi (Shinji)), and spotted alfalfa aphid (Therioaphis maculata (Buckton)) were intensively studied in California alfalfa. The results showed, as expected, that aphid populations across all densities were aggregated; but that ladybird beetle (Hippodamia convergens (G.-M.)) predation increased the degree of aggregation. The distribution parameters of the aphids were estimated using methods developed by Iwao and Kuno (1971

A detailed study of the photo-injection annealing of thermally diffused InP solar cells

A detailed analysis of the annealing of thermally diffused InP solar cells fabricated by the Nippon Mining Co. is presented. The cells were irradiated with 1 MeV electrons, and the induced degradation is measured using deep level transient spectroscopy and low temperature (86 K) IV measurements. Clear recovery of the photovoltaic parameters is observed during low temperature (T is less than 300 K) solar illuminations (1 sun, AMO) with further recovery at higher temperatures (300 less than T less than 500 K). For example, the output of a cell which was irradiated up to a fluence of 1 x 10(exp 16) cm(sup -2) was observed to recover to within 5 percent of the pre-irradiation output. An apparent correlation between the recovery of I(sub sc) and the annealing of the H4 defect and of the minority carrier trapping centers is observed. An apparent correlation between the recovery of VO, and the annealing of the H5 defect is also observed. These apparent correlations are used to develop a possible model for the mechanism of the recovery of the solar cells

MULTITROPHIC MODELS OF PREDATOR-PREY ENERGETICS: I. AGE-SPECIFIC ENERGETICS MODELS—PEA APHID ACYRTHOSIPHON PISUM (HOMOPTERA: APHIDIDAE) AS AN EXAMPLE

A simple age-specific energetics (calories or biomass) model for the growth and development, reproduction, respiration, ageing, and intrinsic survivorship as a function of temperature and per capita energy availability for pea aphid (Acyrthosiphon pisum (Harris)) is reported. The ratio of energy supply-demand is used to scale all of the rates in the model. The maximum demand for energy based upon current state values is used to drive the Frazer-Gilbert functional response model (i.e. food acquisition), which is a component of the metabolic pool model used to assimilate energy to growth, reproduction, respiration, and egestion. The extensive data sets on pea aphid energetics published by Randolph et al. (1975) were used to develop the model. As the model estimates reproduction (Mx ) and survivorship (Lx ) values, extensive published age-specific life-data sets on pea aphids are used to test it. The results suggest: (1) the lower thermal threshold for development is raised and the upper threshold is lowered as food resources are decreased (2) the temperature-dependent rate of development is slowed with decreasing energy resources (3) the size of individuals and reproduction become smaller as temperature approaches the upper and lower thermal thresholds.A simple model for multitrophic level interactions incorporating the acquisition and assimilation functions is presente