Strengthening mechanisms in nanostructured copper/304 stainless steel multilayers

Nanostructured Cu/304 stainless steel (SS) multilayers were prepared by magnetron sputtering. 304SS has a face-centered-cubic (fcc) structure in bulk. However, in the Cu/304SS multilayers, the 304SS layers exhibit the fcc structure for layer thickness of =5 nm in epitaxy with the neighboring fcc Cu. For 304SS layer thickness larger than 5 nm, body-centered-cubic (bcc) 304SS grains grow on top of the initial 5 nm fcc SS with the Kurdjumov-Sachs orientation relationship between bcc and fcc SS grains. The maximum hardness of Cu/304SS multilayers is about 5.5 GPa (factor of two enhancement compared to rule-of-mixtures hardness) at a layer thickness of 5 nm. Below 5 nm, hardness decreases with decreasing layer thickness. The peak hardness of fcc/fcc Cu/304SS multilayer is greater than that of Cu/Ni, even though the lattice-parameter mismatch between Cu and Ni is five times greater than that between Cu and 304SS. This result may primarily be attributed to the higher interface barrier stress for single-dislocation transmission across the {111} twinned interfaces in Cu/304SS as compared to the {100} interfaces in Cu/Ni.

Analysis of flexural isostasy of the northern Andes

The mode in which a lithosphere plate supports overlying topography is greatly driven by the strength of the plate. By analyzing the geophysical signature of lithosphere flexure, in the space and spectral domains, the strength of the plates that support the north Andean mountains and adjacent basins, and the topography of Kenya was investigated. In addition, the effect of windowing on elastic thickness estimates obtained via the coherence method was evaluated. ^ The coherence between the topography and Bouguer gravity spectra of northern South America suggests that the average elastic thickness of the lithosphere is 30 km. Although lateral variations were not resolved by the coherence implementation, these became apparent by modeling the foreland stratigraphy of the Llanos, Barinas and Maracaibo sub-Andean basins. Flexural models reveal a zone of lithosphere weakness beneath the eastern flank of the Eastern Cordillera and western flank of the Venezuelan Andes. The gravity anomaly calculated from these models is consistent with the observed Bouguer gravity anomaly. This zone of weakness appears to separate the strong, old Guyana shield lithosphere from the weaker and probably younger Andean lithosphere. The zone of weakness may correspond to a Paleozoic feature at the western margin of cratonic South America, or a Mesozoic rift arm that weakened the proto-Andean lithosphere. ^ Using synthetic data as well as the northern South America topography and gravity, this study demonstrates that lithosphere strength calculated from the coherence of mirrored data may overestimate the true lithosphere strength. As a result, many lithosphere plates may be weaker than currently thought. In light of this observation, gravity and topography data from Kenya were reevaluated using multitaper spectral techniques. The elastic thickness of this plate, currently undergoing rifting, was estimated at 7 to 8 km, a factor of 2 less than previously estimated. These estimates suggest that despite intense fracturing and sustained tensile stresses, continental lithosphere plates undergoing rifting are able to retain some strength. ^

Landscape and planning: strengthening discussions in the decision-making process

Since the emergence of the European Landscape Convention (ELC) in 2000, the important link between landscape and planning has greatly intensified. Now, more than ever, the fundamental role of the planning system in delivering the ELC’s requirements is recognised. This has been further substantiated within Ireland’s recently published National Landscape Strategy. However it has continually been suggested that decision-making processes need to adapt better to the holistic, valueladen and multidimensional approaches underpinning the ELC. In light of these milestones for the preservation, management and planning of landscape, this research sets out to establish synergies and disparities in the existing relationship between landscape and planning. It investigates detailed evidence of the presence and manifestations of landscape in key processes of day-to-day planning practice in Ireland, from individual planning appeals and ‘special’ cases, to the major strategic instruments that inform the making of landscape policies within development plans. This is set within wider theoretical and policy contexts where the compatibility of landscape and planning is subjected to critical scrutiny and then explored through these practical case studies. Driving this research is the intention to make a case for the planning domain to be an ideal ‘home’ for landscape – in all its deep, multidimensional meaning – and for enhancing landscape arguments and objectives in the face of conflict, competing values and power-plays in the real world. Emerging out of this research is a set of recommendations for how, at a national level, new approaches for decision making for and about landscape can be more effective and meaningful.

The Effect of Foam Core Density on the Flexural and Axial Behaviour of Sandwich Panels of Varying Slenderness with Natural Flax-FRP and Glass-FRP Composite Skins

This study investigates the effect of foam core density and skin type on the behaviour of sandwich panels as structural beams tested in four-point bending and axially compressed columns of varying slenderness and skin thickness. Bio-composite unidirectional flax fibre-reinforced polymer (FFRP) is compared to conventional glass-FRP (GFRP) as the skin material used in conjunction with three polyisocyanurate (PIR) foam cores with densities of 32, 64 and 96 kg/m3. Eighteen 1000 mm long flexural specimens were fabricated and tested to failure comparing the effects of foam core density between three-layer FFRP skinned and single-layer GFRP skinned panels. A total of 132 columns with slenderness ratios (kLe/r) ranging from 22 to 62 were fabricated with single-layer GFRP skins, and one-, three-, and five-layer FFRP skins for each of the three foam core densities. The columns were tested to failure in concentric axial compression using pinned-end conditions to compare the effects of each material type and panel height. All specimens had a foam core cross-section of 100x50 mm with 100 mm wide skins of equal thickness. In both flexural and axial loading, panels with skins comprised of three FFRP layers showed equivalent strength to those with a single GFRP layer for all slenderness ratios and core densities examined. Doubling the core density from 32 to 64 kg/m3 and tripling the density to 96 kg/m3 led to flexural strength increases of 82 and 213%, respectively. Both FFRP and GFRP columns showed a similar variety of failure modes related to slenderness. Low slenderness of 22-25 failed largely due to localized single skin buckling, while those with high slenderness of 51-61 failed primarily by global buckling followed by secondary skin buckling. Columns with intermediate slenderness experienced both localized and global failure modes. High density foam cores more commonly exhibited core shear failure. Doubling the core density of the columns resulted in peak axial load increases, across all slenderness ratios, of 73, 56, 72 and 71% for skins with one, three and five FFRP layers, and one GFRP layer, respectively. Tripling the core density resulted in respective peak load increases of 116, 130, 176 and 170%.

Basalt Fibre Reinforced Polymer Strengthening of Normal Strength Reinforced Concrete Floor Slabs Subject to Arching Effects

With ever increasing demands to strengthen existing reinforced concrete structures to facilitate higher loading due to change of use and to extend service lifetime, the use of fibre reinforced polymers (FRPs) in structural retrofitting offers an opportunity to achieve these aims. To date, most research in this area has focussed on the use of glass fibre reinforced polymer (GFRP) and carbon fibre reinforced polymer (CFRP), with relatively little on the use of basalt fibre reinforced polymer (BFRP) as a suitable strengthening material. In addition, most previous research has been carried out using simply supported elements, which have not considered the beneficial influence of in-plane lateral restraint, as experienced within a framed building structure. Furthermore, by installing FRPs using the near surface mounted (NSM) technique, disturbance to the existing structure can be minimised.
This paper outlines BFRP NSM strengthening of one third scale laterally restrained floor slabs which reflect the inherent insitu compressive membrane action (CMA) in such slabs. The span-to-depth ratios of the test slabs were 20 and 15 and all were constructed with normal strength concrete (~40N/mm2) and 0.15% steel reinforcement. 0.10% BFRP was used in the retrofitted samples, which were compared with unretrofitted control samples. In addition, the bond strength of BFRP bars bonded into concrete was investigated over a range of bond lengths with two different adhesive thicknesses. This involved using an articulated beam arrangement in order to establish optimum bond characteristics for use in strengthening slab samples.

Task-oriented training and lower limb strengthening to improve balance and function after stroke: a pilot study

This study investigated the effects of task-oriented training and strengthening of the affected lower limb on balance and function in people who have suffered a stroke. Sixteen male adults, with a mean age of 58 (SD 6.3) years, undergoing outpatient physiotherapy less than 1 month after a single stroke in the territory of the middle cerebral artery were recruited. Participants were allocated to one of two groups: the strengthening group (SG) or control group (CG). The main measures used were the Berg Balance Scale (BBS), Barthel Index (BI) and Modified Ashworth Scale (MAS). After 12 weeks of intervention, both groups showed improvements in outcome measures. For BBS, there was a significant difference between groups, with an increase of 26 points in the SG and 11 points in the CG. For BI, the SG improved by 39 points and the CG improved by 22 points. After intervention, the difference between groups was not significant. For MAS, differences were not significant, showing that for both groups intervention programmes did not increase spasticity. In conclusion, physiotherapy intervention for postural control dysfunctions after stroke seems to benefit from strength training of the affected lower limb and the practising functional tasks. A large randomized controlled trial is recommended to further investigate the effects of this intervention.

Chemical resistance of lime-based grouts for masonry strengthening

The stone masonry walls are present in many buildings and historical monuments, with undeniable asset value, but also in old buildings housing both in Portugal and in Europe. Most of these buildings in masonry are in certain cases in a high state of degradation needing urgent intervention. This requires the identification of deficiencies and the application of appropriate intervention techniques. One of the possible techniques for structural consolidation works of stone masonry walls is the injection of fluid mortars currently called grouts. The choice of grouts is very important with regard in particular to their chemical and physical properties. In this study, carried out under the Master of Chemical Engineering, two types of lime-based grouts were used, in order to evaluate and compare their chemical resistance due to the crystallization of soluble salts. One of the grouts is a pre-dosed blend commercially available, Mape-Antique I from company Mapei (CA), and the second grout is a mixture prepared in the laboratory (LB), comprising metakaolin, cement, hydrated lime, water and superplasticizer. With the purpose of evaluating the action of sulphates on these grouts, a series of samples underwent several wetting-drying cycles using two different temperatures, 20 °C and 50 °C. During the experiment it was determined the change of weight and compressive strength in the analyzed grouts, as well as the sulphate ion concentration and pH of the solution in which the samples were dipped. The commercial grout (CA) apparently has a greater chemical resistance to sulphates. However grout LB showed to have positive results in some parameters.

Reforming the Swedish employment-related social security system:activation, administrative modernization and strengthening local autonomy

The Swedish system of social security has often been regarded as comprehensive and comprehensive and inclusive. During major reforms in the 1990s and 2000s, it has maintained its essential character as a popular and well-endowed provider of social security and stability. Employment-related benefits are generous in financial terms, but come with the need for recipients to remain actively engaged in the economic or educational field. However, Sweden’s geographical and demographic diversity made it necessary to increase the role of local authorities in implementing active labour market policies. This article tracks these developments since the mid-1990s, both with regard to changing the benefits system and with regard to changing local government involvement. It argues that backed by broad political support, the Swedish system has achieved the necessary modernisation and adaptation to remain a viable alternative to more neo-liberal welfare retrenchment projects conducted in other European countries.

Training and Updating of Education Boards in Indigenous Schools of Rural Areas: Strengthening Local Education Management

Education management in the schools of indigenous rural areas faces a number of difficulties to implement and comply with the guidelines and requirements of the laws related to budgetary management of resources allocated to Education or Administrative Boards. In addition to being located in scattered rural areas, far from the municipal heads and regional offices of the Ministry of Public Education, one of the main obstacles is that all regulations, laws and guidelines are written in Spanish, and there is people, in this indigenous rural communities, who do not speak, write, read or understand this language. This puts them at an enormous disadvantage, which has a direct impact on the indigenous children’s right to education.

Mechanical behaviour and durability assessment of Fibre Reinforced Cementitious Matrix (FRCM) strengthening systems.

In recent years, the seismic vulnerability of existing masonry buildings has been underscored by the destructive impacts of earthquakes. Therefore, Fibre Reinforced Cementitious Matrix (FRCM) retrofitting systems have gained prominence due to their high strength-to-weight ratio, compatibility with substrates, and potential reversibility. However, concerns linger regarding the durability of these systems when subjected to long-term environmental conditions. This doctoral dissertation addressed these concerns by studying the effects of mild temperature variations on three FRCM systems, featuring basalt, glass, and aramid fibre textiles with lime-based mortar matrices. The study subjected various specimens, including mortar triplets, bare textile specimens, FRCM coupons, and single-lap direct shear wallets, to thermal exposure. A novel approach utilizing embedded thermocouple sensors facilitated efficient monitoring and active control of the conditioning process. A shift in the failure modes was obtained in the single lap-direct shear tests, alongside a significant impact on tensile capacity for both textiles and FRCM coupons. Subsequently, bond tests results were used to indirectly calibrate an analytical approach based on mode-II fracture mechanics. A comparison between Cohesive Material Law (CML) functions at various temperatures was conducted for each of the three systems, demonstrating a good agreement between the analytical model and experimental curves. Furthermore, the durability in alkaline environment of two additional FRCM systems, characterized by basalt and glass fibre textiles with lime-based mortars, was studied through an extensive experimental campaign. Tests conducted on single yarn and textile specimens after exposure at different durations and temperatures revealed a significant impact on tensile capacity. Additionally, FRCM coupons manufactured with conditioned textile were tested to understand the influence of aged textile and curing environment on the final tensile behavior. These results contributed significantly to the existing knowledge on FRCM systems and could be used to develop a standardized alkaline testing protocol, still lacking in the scientific literature.