Developing an engineering approach for migrating from prescriptive to performance-based specification for concrete

The integral variability of raw materials, lack of awareness and appreciation of the technologies for achieving quality control and lack of appreciation of the micro and macro environmental conditions that the structures will be subjected, makes modern day concreting a challenge. This also makes Designers and Engineers adhere more closely to prescriptive standards developed for relatively less aggressive environments. The data from exposure sites and real structures prove, categorically, that the prescriptive specifications are inadequate for chloride environments. In light of this shortcoming, a more pragmatic approach would be to adopt performance-based specifications which are familiar to industry in the form of specification for mechanical strength. A recently completed RILEM technical committee made significant advances in making such an approach feasible.
Furthering a performance-based specification requires establishment of reliable laboratory and on-site test methods, as well as easy to perform service-life models. This article highlights both laboratory and on-site test methods for chloride diffusivity/electrical resistivity and the relationship between these tests for a range of concretes. Further, a performance-based approach using an on-site diffusivity test is outlined that can provide an easier to apply/adopt practice for Engineers and asset managers for specifying/testing concrete structures.

Paramilitary punishments in Belfast: policing beneath the peace

As an enduring legacy of the conflict, paramilitary policing remains an unpalatable but indisputable fact within Belfast's working-class, Republican communities. Historically, while much attention has been devoted to the causes and consequences of paramilitarism along with the terrorist threat posed by such organizations, little attention has been paid to the influence upon, or relations between, such nonstate policing actors, the communities in which they exist and the delivery of policing by the Police Service of Northern Ireland. While local and international literature surrounding paramilitary violence has tended towards political axiom or physical impact of such activity, the current paper presents an empirical study of the relations between communities and Republican paramilitary organizations who seek to exploit a perceived dearth of state-based policing at the community level within Belfast. Framing the ontology of paramilitary policing and its support from a community, rather than political or security perspective, the paper argues that continuing grass-roots support for this ‘new’ paramilitary policing within Republican communities of Belfast is more complex and nuanced than the political antecedents of the conflict from which such activity emerged – especially in terms of such support surviving successive political negotiations and police reforms since the ‘Good Friday’ Agreement of 1998.

Improved Real-time State-of-Charge Estimation of LiFePO4 Battery Based on a Novel Thermoelectric Model

Li-ion batteries have been widely used in electric vehicles, and battery internal state estimation plays an important role in the battery management system. However, it is technically challenging, in particular, for the estimation of the battery internal temperature and state-ofcharge (SOC), which are two key state variables affecting the battery performance. In this paper, a novel method is proposed for realtime simultaneous estimation of these two internal states, thus leading to a significantly improved battery model for realtime SOC estimation. To achieve this, a simplified battery thermoelectric model is firstly built, which couples a thermal submodel and an electrical submodel. The interactions between the battery thermal and electrical behaviours are captured, thus offering a comprehensive description of the battery thermal and electrical behaviour. To achieve more accurate internal state estimations, the model is trained by the simulation error minimization method, and model parameters are optimized by a hybrid optimization method combining a meta-heuristic algorithm and the least square approach. Further, timevarying model parameters under different heat dissipation conditions are considered, and a joint extended Kalman filter is used to simultaneously estimate both the battery internal states and time-varying model parameters in realtime. Experimental results based on the testing data of LiFePO4 batteries confirm the efficacy of the proposed method.