Evaluation of infilled frames: an updated in-plane-stiffness macro-model considering the effects of vertical loads

The influence of masonry infills on the in-plane behaviour of RC framed structures is a central topic in the seismic evaluation and retrofitting of existing buildings. Many models in the literature use an equivalent strut member in order to represent the infill but, among the parameters influencing the equivalent strut behaviour, the effect of vertical loads acting on the frames is recognized but not quantified. Nevertheless a vertical load causes a non-negligible variation in the in-plane behaviour of infilled frames by influencing the effective volume of the infill. This results in a change in the stiffness and strength of the system. This paper presents an equivalent diagonal pin-jointed strut model taking into account the stiffening effect of vertical loads on the infill in the initial state. The in-plane stiffness of a range of infilled frames was evaluated using a finite element model of the frame-infill system and the cross-section of the strut equivalent to the infill was obtained for different levels of vertical loading by imposing the equivalence between the frame containing the infill and the frame containing the diagonal strut. In this way a law for identifying the equivalent strut width depending on the geometrical and mechanical characteristics of the infilled frame was generalized to consider the influence of vertical loads for use in the practical applications. The strategy presented, limited to the initial stiffness of infilled frames, is preparatory to the definition of complete non-linear cyclic laws for the equivalent strut.

Non-convex dynamic economic/environmental dispatch with plug-in electric vehicle loads

Electric vehicles are a key prospect for future transportation. A large penetration of electric vehicles has the potential to reduce the global fossil fuel consumption and hence the greenhouse gas emissions and air pollution. However, the additional stochastic loads imposed by plug-in electric vehicles will possibly introduce significant changes to existing load profiles. In his paper, electric vehicles loads are integrated into an 5-unit system using a non-convex dynamic dispatch model. The actual infrastructure characteristics including valve-point effects, load balance constrains and transmission loss have been included in the model. Multiple load profiles are comparatively studied and compared in terms of economic and environmental impacts in order o identify patterns to charge properly. The study as expected shows ha off-peak charging is the best scenario with respect to using less fuels and producing less emissions.

A self-learning teaching-learning based optimization for dynamic economic/environmental dispatch considering multiple plug-in electric vehicle loads

Economic and environmental load dispatch aims to determine the amount of electricity generated from power plants to meet load demand while minimizing fossil fuel costs and air pollution emissions subject to operational and licensing requirements. These two scheduling problems are commonly formulated with non-smooth cost functions respectively considering various effects and constraints, such as the valve point effect, power balance and ramp rate limits. The expected increase in plug-in electric vehicles is likely to see a significant impact on the power system due to high charging power consumption and significant uncertainty in charging times. In this paper, multiple electric vehicle charging profiles are comparatively integrated into a 24-hour load demand in an economic and environment dispatch model. Self-learning teaching-learning based optimization (TLBO) is employed to solve the non-convex non-linear dispatch problems. Numerical results on well-known benchmark functions, as well as test systems with different scales of generation units show the significance of the new scheduling method.

Predicting axial velocity profiles within a diffusing marine propeller jet

A full understanding of the hydrodynamic processes within the jet produced by a manoeuvring ship’s propeller is essential in the development and maintenance of ports, docks and harbours. In this study the predominant axial velocity component of a diffusing propeller jet was studied. The flow fields formed by four propellers, each operating at four power levels (speeds of rotation), were investigated under bollard pull conditions within a large free surface tank using Laser Doppler Anemometry. Comparison were made to existing methodologies by which a prediction of the magnitudes of the axial velocity can be made, and where deficient modifications to the methodologies have been developed. The jets were found to produce a maximum axial velocity along the initial efflux plane at a location near the blade mid-span. The position and magnitude of the axial velocity was seen to decrease as the jet entrained more flow and transitioned from the zone of flow establishment into the zone of established flow.

Extreme Loads on an Oscillating Wave Surge Converter

A major difficulty in the design of full scale Wave Energy Converters is the need to design for two conflicting design criteria. In one instance devices must be designed to couple heavily to the incident wave force resulting in the efficient extraction of energy in small sea states, however devices must also be capable of withstanding the harsh conditions encountered during extreme seas. This paper presents an initial investigation of the extreme wave loading of a generic, surface-piercing, pitching flap-type device deployed in near shore wave conditions. Slamming of the flap is selected as the extreme load event for further investigation and the experimental methodologies employed are described. Preliminary results showing both local and global loading under such events are presented for the case of a flap tested in a 3-dimensional environment. Results are presented which show flap slamming effects on the pressures experienced on the front face of the flap.

Tri-axial accelerometers quantify behaviour in the Eurasian badger (Meles meles): towards an automated interpretation of field data

The popularity of tri-axial accelerometer data loggers to quantify animal activity through the analysis of signature traces is increasing. However, there is no consensus on how to process the large data sets that these devices generate when recording at the necessary high sample rates. In addition, there have been few attempts to validate accelerometer traces with specific behaviours in non-domesticated terrestrial mammals.

Corneal hysteresis and axial length among Chinese secondary school children: the Xichang Pediatric Refractive Error Study (X-PRES) report no. 4.

PURPOSE: To evaluate the association between corneal hysteresis and axial length/refractive error among rural Chinese secondary school children. DESIGN: Cross-sectional cohort study. METHODS: Refractive error (cycloplegic auto-refraction with subjective refinement), central corneal thickness (CCT) and axial length (ultrasonic measurement), intraocular pressure (IOP), and corneal hysteresis (Reichert Ocular Response Analyzer) were measured on a rural school-based cohort of children. RESULTS: Among 1,233 examined children, the mean age was 14.7 +/- 0.8 years and 699 (56.7%) were girls. The mean spherical equivalent (n = 1,232) was -2.2 +/- 1.6 diopters (D), axial length (n = 643) was 23.7 +/- 1.1 mm, corneal hysteresis (n = 1,153) was 10.7 +/- 1.6 mm Hg, IOP (n = 1,153) was 17.0 +/- 3.4 mm Hg, and CCT (n = 1,226) was 553 +/- 33 microns. In linear regression models, longer axial length was significantly (P < .001 for both) associated with lower corneal hysteresis and higher IOP. Hysteresis in this population was significantly (P < .001) lower than has previously been reported for normal White children (n = 42, 12.3 +/- 1.3 mm Hg), when adjusting for age and gender. This difference did not appear to depend on differences in axial length between the populations, as it persists when only Chinese children with normal uncorrected vision are included. CONCLUSIONS: Prospective studies will be needed to determine if low hysteresis places eyes at risk for axial elongation secondary or if primary elongation results in lower hysteresis.

Corneal biomechanics, refractive error, and axial length in Chinese primary school children.

PURPOSE: Low corneal hysteresis is associated with longer axial length in Chinese secondary school children. The authors sought to explore this association in primary school children. METHODS: LogMAR presenting visual acuity, cycloplegic refractive error, ocular biometry, central corneal thickness (CCT), and corneal hysteresis (CH) was assessed for children in grades 1 to 3 at an academically competitive urban school in Shantou, China. RESULTS: Among 872 eligible children (mean age, 8.6 ± 2.1 years), 651 (74.7%) completed the examination. Among 1299 examined eyes, 111 (8.5%) had uncorrected vision ≤6/12. Mean spherical equivalent refractive error for all eyes was +0.26 ± 1.41 D, and axial length (AL) was 22.7 ± 0.90 mm. CH for the lowest (mean AL, 21.7 ± 0.39 mm), two middle (mean AL, 22.4 ± 0.15 and 22.9 ± 0.15 mm), and highest quartiles (mean AL, 23.7 ± 0.74 mm) of AL were 10.6 ± 2.1 mm Hg, 10.4 ± 2.1 mm Hg, 10.3 ± 2.3 mm Hg, and 10.2 ± 2.3 mm Hg respectively (age- and gender-adjusted Pearson's correlation coefficient r = -0.052; P = 0.001). In generalized estimating equation models adjusting for age, gender, and CCT, lower CH was significantly associated with longer AL (P < 0.001) and more myopic refractive error (P = 0.001). CONCLUSIONS: CH measurement is practical in young children because this is when myopia undergoes its most rapid progression. Prospective follow-up of this cohort at high risk for myopia is under way to determine whether low CH is predictive, or a consequence, of long AL.

Corneal hysteresis is correlated with reduction in axial length after trabeculectomy.

BACKGROUND: We sought to determine whether corneal biomechanical parameters are predictive of reduction in axial length after anti-metabolite trabeculectomy. METHODS: Chinese subjects undergoing trabeculectomy with mitomycin C by a single experienced surgeon underwent the following measurements: Corneal hysteresis (CH, Ocular Response Analyzer, Reichert Ophthalmic Instruments), Goldmann intra-ocular pressure (IOP), central corneal thickness (CCT) and axial length (AL, IOLMaster, Carl Zeiss Meditec, Dublin, CA) were measured pre-operatively, and AL, CH and IOP were measured 1 day and 1 week post-operatively. RESULTS: Mean age of 31 subjects was 52.0 ± 15.2 years, and 15 (48.4%) were female. The mean pre-operative IOP of 21.4 ± 9.3 mmHg was reduced to 8.2 ± 4.6 mmHg 1 day and 11.0 ± 4.4 mmHg 1 week post-operatively (p < 0.001). AL declined from 22.99 ± 0.90 to 22.76 ± 0.87 mm at 1 day and 22.74 ± 0.9 mm at 1 week; 30/31 (%) eyes had a decline in AL (p < 0.001, sign test). In multivariate linear regression models including post-operative data from 1 day and 1 week, greater decline in Goldmann IOP (p < 0.0001, greater pre-op axial length (p < 0.001) and lower pre-operative CH (p = 0.03), were all associated with greater decline in post-operative axial length. CONCLUSIONS: Eyes with lesser ability of the ocular coat to absorb energy (lower CH) had significantly greater decrease in axial length after trabeculectomy-induced IOP-lowering.

Validation of a 3D damage model for predicting the response of composite structures under crushing loads

A 3D intralaminar continuum damage mechanics based material model, combining damage mode interaction and material nonlinearity, was developed to predict the damage response of composite structures undergoing crush loading. This model captures the structural response without the need for calibration of experimentally determined material parameters. When used in the design of energy absorbing composite structures, it can reduce the dependence on physical testing. This paper validates this model against experimental data obtained from the literature and in-house testing. Results show that the model can predict the force response of the crushed composite structures with good accuracy. The simulated energy absorption in each test case was within 12% of the experimental value. Post-crush deformation and the damage morphologies, such as ply splitting, splaying and breakage, were also accurately reproduced. This study establishes the capability of this damage model for predicting the responses of composite structures under crushing loads.

Biaxial seismic behaviour of reinforced concrete columns

A análise dos efeitos dos sismos mostra que a investigação em engenharia sísmica deve dar especial atenção à avaliação da vulnerabilidade das construções existentes, frequentemente desprovidas de adequada resistência sísmica tal como acontece em edifícios de betão armado (BA) de muitas cidades em países do sul da Europa, entre os quais Portugal. Sendo os pilares elementos estruturais fundamentais na resistência sísmica dos edifícios, deve ser dada especial atenção à sua resposta sob ações cíclicas. Acresce que o sismo é um tipo de ação cujos efeitos nos edifícios exige a consideração de duas componentes horizontais, o que tem exigências mais severas nos pilares comparativamente à ação unidirecional. Assim, esta tese centra-se na avaliação da resposta estrutural de pilares de betão armado sujeitos a ações cíclicas horizontais biaxiais, em três linhas principais. Em primeiro lugar desenvolveu-se uma campanha de ensaios para o estudo do comportamento cíclico uniaxial e biaxial de pilares de betão armado com esforço axial constante. Para tal foram construídas quatro séries de pilares retangulares de betão armado (24 no total) com diferentes características geométricas e quantidades de armadura longitudinal, tendo os pilares sido ensaiados para diferentes histórias de carga. Os resultados experimentais obtidos são analisados e discutidos dando particular atenção à evolução do dano, à degradação de rigidez e resistência com o aumento das exigências de deformação, à energia dissipada, ao amortecimento viscoso equivalente; por fim é proposto um índice de dano para pilares solicitados biaxialmente. De seguida foram aplicadas diferentes estratégias de modelação não-linear para a representação do comportamento biaxial dos pilares ensaiados, considerando não-linearidade distribuída ao longo dos elementos ou concentrada nas extremidades dos mesmos. Os resultados obtidos com as várias estratégias de modelação demonstraram representar adequadamente a resposta em termos das curvas envolventes força-deslocamento, mas foram encontradas algumas dificuldades na representação da degradação de resistência e na evolução da energia dissipada. Por fim, é proposto um modelo global para a representação do comportamento não-linear em flexão de elementos de betão armado sujeitos a ações biaxiais cíclicas. Este modelo tem por base um modelo uniaxial conhecido, combinado com uma função de interação desenvolvida com base no modelo de Bouc- Wen. Esta função de interação foi calibrada com recurso a técnicas de otimização e usando resultados de uma série de análises numéricas com um modelo refinado. É ainda demonstrada a capacidade do modelo simplificado em reproduzir os resultados experimentais de ensaios biaxiais de pilares.

Electrospun pH-sensitive core–shell polymer nanocomposites fabricated using a tri-axial process

A modified tri-axial electrospinning process was developed for the generation of a new type of pH-sensitive polymer/lipid nanocomposite. The systems produced are able to promote both dissolution and permeation of a model poorly water-soluble drug. First, we show that it is possible to run a tri-axial process with only one of the three fluids being electrospinnable. Using an electrospinnable middle fluid of Eudragit S100 (ES100) with pure ethanol as the outer solvent and an unspinnable lecithin-diclofenac sodium (PL–DS) core solution, nanofibers with linear morphology and clear core/shell structures can be fabricated continuously and smoothly. X-ray diffraction proved that these nanofibers are structural nanocomposites with the drug present in an amorphous state. In vitro dissolution tests demonstrated that the formulations could preclude release in acidic conditions, and that the drug was released from the fibers in two successive steps at neutral pH. The first step is the dissolution of the shell ES100 and the conversion of the core PL–DS into sub-micron sized particles. This frees some DS into solution, and later the remaining DS is gradually released from the PL–DS particles through diffusion. Ex vivo permeation results showed that the composite nanofibers give a more than twofold uplift in the amount of DS passing through the colonic membrane as compared to pure DS; 74% of the transmitted drug was in the form of PL–DS particles. The new tri-axial electrospinning process developed in this work provides a platform to fabricate structural nanomaterials, and the core–shell polymer-PL nanocomposites we have produced have significant potential applications for oral colon-targeted drug delivery.

Intelligent management of end consumers loads including electric vehicles through a SCADA system

The large penetration of intermittent resources, such as solar and wind generation, involves the use of storage systems in order to improve power system operation. Electric Vehicles (EVs) with gridable capability (V2G) can operate as a means for storing energy. This paper proposes an algorithm to be included in a SCADA (Supervisory Control and Data Acquisition) system, which performs an intelligent management of three types of consumers: domestic, commercial and industrial, that includes the joint management of loads and the charge/discharge of EVs batteries. The proposed methodology has been implemented in a SCADA system developed by the authors of this paper – the SCADA House Intelligent Management (SHIM). Any event in the system, such as a Demand Response (DR) event, triggers the use of an optimization algorithm that performs the optimal energy resources scheduling (including loads and EVs), taking into account the priorities of each load defined by the installation users. A case study considering a specific consumer with several loads and EVs is presented in this paper.