Systems engineering methodologies, tacit knowledge and communities of practice

In the context of technology development and systems engineering, knowledge is typically treated as a complex information structure. In this view, knowledge can be stored in highly sophisticated data systems and processed by explicitly intelligent, software-based technologies. This paper argues that the current emphasis upon knowledge as information (or even data) is based upon a form of rationalism which is inappropriate for any comprehensive treatment of knowledge in the context of human-centred systems thinking. A human-centred perspective requires us to treat knowledge in human terms. The paper sets out the particular importance of tacit knowledge in this regard. It sets out two case studies which reveal the critical importance of a careful treatment of tacit knowledge for success in two complex, technology-driven projects.

Ultrasonic reflection from a stressed interface

In seeking to develop an NDE technique for verifying the serviceability of NiTi couplers for plumbing unions, it was found that the reflection coefficient for a normally incident ultrasonic wave correlated with the stress level at the NiTi-tubing interface. Current theory pertaining to interface reflection is not complete but, even at present status, there is semiquantitative accord between theoretical predictions and normalized data for reflection coefficient versus stress level. These results are at fixed frequency and with comparable surface roughness. Variation of either frequency or surface roughness further affects the reflection coefficient. Current studies are being pursued to define this effect.     

Three or two times daily milking of older cows and first lactation cows for entire lactations

Thirty-eight older (second and greater lactation) and 15 Holstein cows in first lactation were in a full lactation (44 wk) study to evaluate the effect of either twice or three times daily milking on yield of milk and milk components, milk composition, feed intake, and body weight change. All cows were managed alike and were fed diets of high, medium, and low energy concentration as lactation progressed from calving to 44 wk. First lactation cows were switched from diets of high energy to lower energy at the same milk production as lactation advanced. Dietary changes for older cows milked twice and three times (A) were at similar production, whereas three times (B) cows were switched to lower energy at higher milk production. Older cows milked three times daily (A and B) produced 17 and 13% more milk over the entire lactation than cows milked twice daily. Dry matter and energy intakes were not affected by three times milking, but gain of body weight was reduced. Cows milked three times daily during their first lactation produced 6% more milk than their twice counterparts, although this increase was not significant. Dry matter and energy intakes were not affected by three times daily milking, but three times milking of first lactation cows reduced weight gain over the lactation. Reproductive performance of cows milked three times daily was not significantly different from cows milked twice daily. Herds milking three times will require high management of nutrition and reproduction.     

The restraining effect of ductile ligaments on plane strain crack propagation and arrest in ferritic steels

In the transition regime plain strain crack propagation in ferritic steels proceeds by a combination of cleavage and ductile rupture processes, the latter being confined to ligaments that are parallel to the direction of macroscopic crack propagation. These ligaments rupture as the crack propagates, and it is generally accepted that they have a restraining effect on crack propagation, and also provide a major contribution to the arrest fracture toughness $\text{K}{}_{\mathrm{Ia}}$. In modelling the propagation and arrest phenomena, and in quantifying this restraining effect, it is tempting to average the effect of the discrete ligaments over a region behind the crack tip. The results of this paper's theoretical analysis justify the use of the averaging procedure.     

Developing a pragmatic evaluation of ICTs for older adults with cognitive impairment at scale: the IN LIFE experience

Implementing information and communications technology (ICT) at scale requires evaluation processes to capture the impact on users as well as the infrastructure into which it is being introduced. For older adults living with cognitive impairment, this requires evaluation that can accommodate different levels of cognitive impairment, alongside input from family and formal caregivers, plus stakeholder organisations. The European Horizon 2020 project INdependent LIving support Functions for the Elderly (IN LIFE) set out to integrate 17 technologies into a single digital platform for older people living with cognitive impairment plus their families, care providers and stakeholders. The IN LIFE evaluation took place across six national pilot sites to examine a number of variables including impact on the users, user acceptance of the individual services and the overall platform, plus the economic case for the IN LIFE platform. The results confirmed the interest and need among older adults, family caregivers, formal caregivers and stakeholders, for information and communications technology (ICT). Relative to the baseline, quality of life improved and cognition stabilised; however, there was an overall reluctance to pay for the platform. The findings provide insights into existing barriers and challenges for adoption of ICT for older people living with cognitive impairment.

     

Local search genetic algorithm for optimal design of reliablenetworks

This paper presents a genetic algorithm (GA) with specialized encoding, initialization, and local search operators to optimize the design of communication network topologies. This NP-hard problem is often highly constrained so that random initialization and standard genetic operators usually generate infeasible networks. Another complication is that the fitness function involves calculating the all-terminal reliability of the network, which is a computationally expensive calculation. Therefore, it is imperative that the search balances the need to thoroughly explore the boundary between feasible and infeasible networks, along with calculating fitness on only the most promising candidate networks. The algorithm results are compared to optimum results found by branch and bound and also to GA results without local search operators on a suite of 79 test problems. This strategy of employing bounds, simple heuristic checks, and problem-specific repair and local search operators can be used on other highly constrained combinatorial applications where numerous fitness calculations are prohibitive     

Embedded blended learning within an Algebra classroom: a multimedia capture experiment

This two‐group, pretest‐posttest, quasi‐experimental study compared secondary students' learning of Algebra II materials over a 4‐week period when identical instruction by the same teacher was delivered through either embedded blended learning (treatment group; n = 32) or a live‐lecture classroom (control group; n = 24). For both groups, instruction was delivered in a normal classroom setting. A math test and a student survey were used to measure students' learning of Algebra II and satisfaction with the instruction. Students in the treatment group showed significantly greater gains in Algebra II test scores and evaluated their learning experiences significantly more positively than did the control group. The great majority (80%) of students in the treatment group preferred the embedded blended learning over traditional live lectures for future learning of math. Students' responses to open‐ended survey questions suggested that students in the treatment group appreciated the: (a) ability to control the pace of instruction; (b) new role of the classroom teacher; (c) lack of distraction in the blended learning environment; and (d) accessibility of the embedded multimedia lessons outside the classroom. This study suggests that screen‐capture instructional technology can be used towards establishing a teacher‐based, embedded blended learning environment within a secondary algebraic classroom.     

A bibliography of applications of operational research in West Africa

There is considerable interest in the potential for using operational research (O.R.) in developing countries. One sign of this is the formation of new societies for O.R. scientists in countries and regions where no such society had existed. Since 2003, such societies have been formed in several parts of Africa. This paper focuses on West Africa, and presents a bibliography of papers relating to applications of O.R. in the nations of this part of the continent. The paper describes the way in which the bibliography was collated and discusses the overall picture that the list of papers presents of the state of O.R. in the 18 countries that are considered.     

Modelling of the interframe dependence in an HMM using conditional Gaussian mixtures

This paper investigates the modelling of the interframe dependence in a hidden Markov model (HMM) for speech recognition. First, a new observation model, assuming dependence on multiple previous frames, is proposed. This model represents such a dependence structure with a weighted mixture of a set of first-order conditional Gaussian densities, each mixture component accounting for a specific conditional frame. Next, an optimization in choosing the conditional frames/segment is performed in both training and recognition, thereby helping to remove the mismatch of the conditional segments due to different observation histories. An EM (Expectation–Maximization) iteration algorithm is developed for the estimation of the model parameters and for the optimization over the dependence structure. Experimental comparisons on a speaker-independent E-set database show that the new model, without optimization on the dependence structure, achieves better performance than the standard HMM, the bigram HMM and the linear-predictive HMM, all in comparable or smaller parameter sizes. The optimization over the dependence structure leads to further improvement in the performance.