Time-averaged single sided ventilation rates and thermal environment in cooling mode for a low energy retrofit envelope

Non-invasive, scalable, building retrofit solutions are very attractive deep renovation techniques to improve energy efficiency in existing buildings; this includes natural ventilation for cooling due to the low impact nature of the installation. However, a number of criteria that are important to natural ventilative cooling strategies can be substantially altered as a result of an external retrofit solution. This paper investigates this experimentally; it presents ventilation rate and internal thermal environment results from full scale testing of a modular, scalable, external low energy retrofit envelope solution applied to an existing 1970s precast concrete building in Ireland. Experimental results of time averaged single sided ventilation rates for three different ventilation opening configurations in a retrofitted office space during a warm and low wind summer period are analysed and compared to a single configuration control space. Results show that the highest time averaged ventilation rates were measured in the control space although a similar distribution was present in one retrofit opening configuration. Analysis of tracer concentration decay fluctuation profiles during tests suggest increased unsteady flow effects in the control space compared to all retrofit configurations. This is likely due to the different responses to turbulent diffusion processes and wind pressure fluctuations at the window opening compared to the louvred retrofit design. Zone thermal stratification and diurnal temperature variation within the control and retrofit spaces were measured during each ventilation rate test and also continuously for an extended period. Results show that vertical temperature differences have been substantially reduced following the retrofit works with all δTs values within recommended acceptable limits.The original pilot project works was supported through a grant from the Department of Education and Skills, Ireland

Agent-based models and individualism: is the world agent-based?

Agent-based models (ABMs) are an increasingly popular tool in the social sciences. This trend seems likely to continue, so that they will become widely used in geography and in urban and regional planning. We present an overview of examples of these models in the life sciences, economics, planning, sociology, and archaeology. We conclude that ABMs strongly tend towards an individualist view of the social world. This point is reinforced by closer consideration of particular examples. This discussion pays attention to the inadequacy of an individualist model of society with reference to debates in social theory. We argue that because models are closed representations of an open world it is important that institutions and other social structures be explicitly included, or that their omission be explained. A tentative explanation for the bias of ABMs is offered, based on an examination of early research in artificial intelligence and distributed artificial intelligence from which disciplines the approach is derived. Some implications of these findings are discussed. We indicate some useful research directions which are beginning to tackle the individualism issue directly. We further note that the underlying assumptions of ABMs are often hidden in the implementation details. We conclude that such models must be subject to critical examination of their assumptions, and that model builders should engage with social theory if the approach is to realise its full potential

Use of genetic markers for the detection of off-types for DUS phenotypic traits in the inbreeding crop, barley

Detection of crop off-types is of interest for multiple uses, including the assessment of uniformity for new plant variety applications during distinctness, uniformity and stability (DUS) testing for the awarding of plant breeders’ rights (PBR). Here, we investigate whether genetic markers, in this case Kompetitive Allele-Specific PCR (KASP), can be used for the identification off-types for phenotypes assessed for DUS in the inbreeding cereal crop, barley (Hordeum vulgare). To demonstrate proof of principle, KASP markers diagnostic for phenotypic expression of nine DUS phenotypes, and DNA from two barley varieties (‘Pelican’ and ‘Felicie’) carrying contrasting alleles at each marker were used. We found that for the majority of markers, it was possible to robustly call alleles down to template DNA concentrations of 2 ng, but not ≤ 0.2 ng. When used in mixtures of DNA consisting of ‘Felicie’ DNA spiked with different concentrations of ‘Pelican’ DNA, robust allele calling was possible in DNA mixtures down to 18 ng:2 ng. Collectively, this demonstrates that where diagnostic markers are available, molecular identification of a single off-type for a given DUS trait within a bulk of ten individuals should be possible. We validated this assumption, with all of the diagnostic genetic markers investigated found to robustly detect DUS off-types at a frequency of 10% in DNA extracted from tissue collected from pools of 10 individuals. Ultimately, this work demonstrates that, where diagnostic polymorphisms are known for DUS traits, KASP markers should be able to robustly detect off-types or cross-contamination within DNA samples from a diploid inbred species down to 10%. While just two varieties that contrasted for the eight DUS targeted were investigated in this study, as the markers used are diagnostic for their relevant phenotype (or a proportion of the variation observed for that phenotype), in theory the approach should be valid for any variety studied— although the introduction of novel alleles via spontaneous mutation or more exotic germplasm pools may mean that marker sets would need to be periodically added to or updated. However, we nevertheless demonstrate the principle that, for a subset of DUS traits, molecular markers can now be robustly used as a tool towards determining all three components of the DUS testing process in barley. These results are relevant for the assessment of varietal uniformity by crop breeders, crop testing authorities and germplasm maintenance, as well as highlighting the potential use of bulk samples rather than individual plant samples for assessment of distinctness by molecular methods

Empirical assessment of the critical time increment in explicit particulate discrete element method simulations

This contribution considers the critical time increment (〖∆t〗_crit) to achieve stable simulations using particulate discrete element method (DEM) codes that adopt a Verlet-type time integration scheme. The 〖∆t〗_crit is determined by considering the maximum vibration frequency of the system. Based on a series of parametric studies, 〖∆t〗_crit is shown to depend on the particle mass (m), the maximum contact stiffness (Kmax), and the maximum particle coordination number (CN,max). Empirical expressions relating 〖∆t〗_crit to m, Kmax, and CN,max are presented; while strictly only valid within the range of simulation scenarios considered here, these can inform DEM analysts selecting appropriate 〖∆t〗_crit values

SAW torque transducers for disturbance rejection and tracking control of multi-inertia servo-drive systems

The paper proposes a resonance ratio control (RRC) technique for the coordinated motion control of multi-inertia mechanical systems, based on the measurement of shaft torque via a SAW-based torque sensor. Furthermore, a new controller structure, RRC plus disturbance feedback is proposed, which enables the controller to be designed to independently satisfy tracking and regulation performance. A tuning method for the RRC structure is given based on the ITAE index, normalized as a function of the mechanical parameters enabling a direct performance comparison between a basic proportional and integral (PI) controller. The use of a reduced-order state observer is presented to provide a dynamic estimate of the load-side disturbance torque for a multi-inertia mechanical system, with an appraisal of the composite closed-loop dynamics. It is shown that the integrated formulation of the tuning criteria enables lower bandwidth observers to be implemented with a corresponding reduction in noise and computational load. The control structures are experimentally validated via a purpose designed test facility and demonstrate significant improvement in dynamic tracking performance, whilst additionally rejecting periodic load side disturbances, a feature previously unrealisable except by other, high-gain control schemes that impose small stability margins

Observer based tuning techniques and integrated SAW torque transducers for two-inertia servo-drive systems

A controller design and tuning methodology is proposed that facilitates the rejection of periodic load-side disturbances applied to a torsional mechanical system, whilst simultaneously compensating for the disturbance observer's inherent phase delay, thereby facilitating the used of lower bandwidth, practically realisable, disturbance observers. The merits of implementing both a full- and reduced order observer, is investigated, with the latter being implemented with a new low-cost, high-bandwidth torque sensing device based on surface acoustic wave technolog

"So go downtown": simulating pedestrian movement in town centres

Pedestrian movement models have been developed since the 1970s. A review of the literature shows that such models have been developed to explain and predict macro, meso, and micro movement patterns. However, recent developments in modelling techniques, and especially advances in agent-based simulation, open up the possibility of developing integrative and complex models which use existing models as 'building blocks'. In this paper we describe such integrative, modular approach to simulating pedestrian movement behaviour. The STREETS model, developed by using Swarm and GIS, is an agent-based model that focuses on the simulation of the behavioural aspects of pedestrian movement. The modular structure of the simulation is described in detail. This is followed by a discussion of the lessons learned from the development of STREETS, especially the advantages of adopting a modular approach and other aspects of using the agent-based paradigm for modelling

STREETS: an agent-based pedestrian model.

8-11 Septembe