Local Strengthening Research Articles

Local Laser Heat Treatment in Dual-Phase Steels

This research deals with processes leading to local strengthening effects in hot-rolled dual-phase (DP) steels. For this purpose, a method was investigated to achieve local strengthening, namely, local laser heat treatment (LHT). DP sheet steels were globally and homogenously deformed with different degrees of prestrains by cold rolling and subsequently locally heat treated by laser. Following this treatment with selected parameters, the microstructure of the surface and cross section of the heat-treated area as well as the mechanical properties were evaluated by light optical microscopy (LOM), scanning electron microscopy (SEM), as well as transmission electron microscopy (TEM), hardness measurement, and tensile testing. It can be stated that with partial heat treatment, local high strengthening can be produced. At lower heat treating temperatures, this effect could be attributed to bake hardening (BH). Increasing the prestrain as well as temperature results in improving the local properties. With increased heat treating temperature, the initial microstructure near the surface is affected. Partial strengthening of DP steels by laser can open up new fields of application for locally using the strengthening effect to only influence relevant areas of interest, thus providing the potential for saving energy and designed the component’s behavior.

Mathematical modeling of the stress state of a transverse plastic layer in a round rod

We construct mathematical models of plastic deformations of a continuous round rod containing a transverse (less strong) inhomogeneous layer under an axial load. We thoroughly study the local strengthening of such layers by involving the base material of the rod in the plastic deformation process. We obtain explicit formulas for the critical stress states in the layer and the critical axial load on the rod.

Modelling impact of northerly wind-generated waves on sediments resuspensions in the Dover Strait and adjacent waters

A numerical approach based on the coupling of the wave propagation module SWAN (Simulating WAves Nearshore) with the three-dimensional circulation module COHERENS (COupled Hydrodynamical-Ecological model for RegioNal and Shelf seas) is developed to simulate the impact of a northerly wind-generated storm on the resuspensions of heterogeneous sediments in the Dover Strait and adjacent waters. Suspended sediment transport is computed for the four grain-size classes of silts ( d 1 = 25 μ m ) , very fine sands ( d 2 = 75 μ m ) , fine sands ( d 3 = 150 μ m ) and medium sands ( d 4 = 350 μ m ) . Predicted times histories of wave variables and the near-bottom mean current and total suspended sediment concentration (SSC) are compared with field data collected off Merlimont Beach, in the south of Boulogne-sur-Mer. Mappings of the growth of the near-bottom total SSC during the storm are produced. The total SSC increases by four at the Merlimont site. The multiplying factor reaches 40 along the exposed northern French coastline revealing the Flandres bed features. This increase is limited to five in deep waters of the southern Dover Strait with local strengthening on the top of the Vergoyer and the Bassure de Baas sandbanks. The storm modifies the granulometric composition of suspended materials by increasing the contribution of medium sands. Main modifications appear at the south-western entrance of the Dover Strait and in the exposed southern North Sea. The near-bottom resuspensions remain elsewhere dominated by the local resuspensions of fine sands added to remote resuspended silts advected by currents.

Seismic analysis of a building block

This paper reports on the study of the seismic response of an urban building block located in Faial, a town of the Horta Island of the Azores, Portugal. The work fits within the framework of studying strengthening schemes suitable for the reconstruction process of a town damaged by an earthquake action and includes numerical modelling of all the building blocks with calibration of material and structural parameters based on ambient vibration tests. The study aims at understanding a number of issues that are likely to influence the global behaviour of the block and the local response of individual buildings, namely the group effect of adjacent constructions, the in-plane stiffness of floors and/or roofs and the presence of possible localized strengthening interventions in selected parts of the block.

The San Francisco Community Vital Signs

A coalition of local public health system stakeholders in San Francisco developed a community assessment and strategic planning tool, the San Francisco Community Vital Signs (SFCVS). The SFCVS builds on the Mobilizing for Action through Planning and Partnerships (MAPP) model by incorporating Internet-based technology into local public health system evaluation and strengthening. This article describes the overlap between the SFCVS and MAPP processes, the manner in which information technology facilitated the SFCVS process, and a template for infusing a Web-based platform into the MAPP model. Internet-based applications helped to implement many (16 of 41; 39%) of the components of the SFCVS process. Of these 16 process measures, the majority (10; 63%) required the use of Web-based technology. The SFCVS demonstrates that a MAPP-like process can leverage the Internet to augment the functionality of public health activities.

Laser Local Stripe Bionic Strengthening of Mould Surface

In order to solve the problems of the waste of resources, and reduce the cost directly caused by the short life of the hot die in enterprises, this paper analyzes the wear of hot die which is one of the main factors affecting service life, and a thought that enhanced mold through laser surface local stripe grid bionic process is pointed out. Different from traditional laser hardening technology, the service life of mold processed by bionic laser melting enhancement simulating butterfly wings is nearly doubled. Experimental results provide a new way to improve die life, and the application of laser local stripe grid bionic process will bring enterprises significant economic benefits for its extension in mould industry.

Fracture Parameters for Natural Rubber Under Dynamic Loading

Abstract: An experimental study was conducted to evaluate the tear energy of unfilled and 25 phr carbon black‐filled natural rubber with varying loading rates. The variation of the tear energy with far‐field sample strain rate between 0.01 to 10 s−1 was found to be different from tensile strip and pure shear specimens. Above a sample strain rate of 10 s−1, the tear energy calculated from either specimen was comparable. The differences in the tear energy derived from the tensile strip and pure shear specimens were attributed to differences in the local crack tip stress state and strengthening of the material due to strain‐induced crystallisation. Both of these factors resulted in crack speeds 3–4 times higher in the pure shear specimen as compared to the tensile strip specimen. Finite element analysis (FEA) indicated that fracture would initiate at the crack tip either when the strain energy density approached the material toughness or when the maximum principal stress and strain approached the material tensile strength and fracture strain, respectively. It was concluded that these parameters would be better than the tear energy in predicting fracture of natural rubber under dynamic loading.

Community mobilisation and health management committee strengthening to increase birth attendance by trained health workers in rural Makwanpur, Nepal: study protocol for a cluster randomised controlled trial

BackgroundBirth attendance by trained health workers is low in rural Nepal. Local participation in improving health services and increased interaction between health systems and communities may stimulate demand for health services. Significant increases in birth attendance by trained health workers may be affected through community mobilisation by local women's groups and health management committee strengthening. We will test the effect of community mobilisation through women's groups, and health management committee strengthening, on institutional deliveries and home deliveries attended by trained health workers in Makwanpur District.DesignCluster randomised controlled trial involving 43 village development committee clusters. 21 clusters will receive the intervention and 22 clusters will serve as control areas. In intervention areas, Female Community Health Volunteers are supported in convening monthly women's groups. The groups work through an action research cycle in which they consider barriers to institutional delivery, plan and implement strategies to address these barriers with their communities, and evaluate their progress. Health management committees participate in three-day workshops that use appreciative inquiry methods to explore and plan ways to improve maternal and newborn health services. Follow-up meetings are conducted every three months to review progress. Primary outcomes are institutional deliveries and home deliveries conducted by trained health workers. Secondary outcome measures include uptake of antenatal and postnatal care, neonatal mortality and stillbirth rates, and maternal morbidity.Trial registration numberISRCTN99834806

Principle of localization of solutions of the Cauchy problem for one class of degenerate parabolic equations of Kolmogorov type

In the case where initial data are generalized functions of the Gevrey-distribution type for which the classical notion of equality of two functions on a set is well defined, we establish the principle of local strengthening of the convergence of a solution of the Cauchy problem to its limit value as t → +0 for one class of degenerate parabolic equations of the Kolmogorov type with $ \overrightarrow {2b} $ -parabolic part whose coefficients are continuous functions that depend only on t.

Local Laser Strengthening of Steel Sheets for Load Adapted Component Design in Car Body Structures

The current trend in car body construction concerning light weight design and car safety improvement increasingly requires an adaption of the local material properties on the component load. Martensitic hardenable steels, which are typically used in car body components, show a significant hardening effect, for instance in laser welded seams. This effect can be purposefully used as a local strengthening method. For several steel grades the local strengthening, resulting from a laser remelting process was investigated. The strength in the treated zone was determined at crash relevant strain rates. A load adapted design of complex reinforcement structures was developed for compression and bending loaded tube samples, using numerical simulation of the deformation behavior. Especially for bending loaded parts, the crash energy absorption can be increased significantly by local laser strengthening.

Development of Ductile Iron Material, Simulation and Production Technology to Locally Strengthen Castings

A lot of innovations in molding and casting technology and also simulation techniques have made ductile iron more and more competitive and it even competes meanwhile against steel forgings. A successful substitution of steel forgings for example is the wheel carrier for a high volume car with the Georg Fischer new ductile iron material 'SiboDur', a ductile iron family with high strength and high elongation at the same time. But there is still a great potential for ductile iron castings to substitute steel forgings, in particular in the automotive industry. One example is the crankshaft for the engine: Quite a lot of gasoline engines are equipped with ductile iron crankshafts, but for instance most of the diesel engines are still running with forged steel cranks. The reason is mostly the belief of design engineers that it is not possible to get similar fatigue limit with castings com-pared to forged steel. This belief may often be correct, but using local strengthening technologies, such as roller burnishing of bearing fillets or inductive hardening of highly stressed areas can raise the fatigue limit of casted crankshafts dramatically. The paper presents studies which show that using the right ductile iron material and optimized roller burnishing conditions can raise the fatigue limit of cast crankshafts to values even higher than forged steel ones (material 38MnVS6). But even quenched and tempered forged steel crankshafts are in the focus to be substituted by castings. It is well known that ductile iron also can be induction hardened, but the induction hardening of ductile iron is still an empirical technology. This leads to the second part of the paper: In a cooperation of Georg Fischer and RWP a research project was carried out to develop a simulation technology to predict the residual stresses in a cast crankshaft due to induction hardening under different condi-tions. The results are very encouraging and enable us today to predetermine the induction hardening conditions to get optimized fatigue behavior of ductile iron crankshafts. Of course, the findings can also be used for other applications than crankshafts.

Experimental Study on the Bending Properties of GFRP Middle Beam in Foundation Pit Support

The laboratory studies on the mechanical properties of the GFRP beams with two different sections are carried out. Their mechanical behavior and the failure features are described and analyzed. The test results indicate that the stability of the GFRP middle beam and the local strength at the joint between the web and the flange are the main factors in the design of the composite middle beams. Based on the test results, a new-style GFRP middle beam with- I-section and double webs is proposed and designed. Loading test shows that the composite material with I-section and double webs can satisfy the requirements for the globe and local stabilities, and simultaneously the material strengths of the middle beam can also be fully utilized. Maybe the proposed new-style beam is the best section type for the middle beam. Also, local strengthening should be adopted in the middle beam-bolt joint.

Use of the Aging Effect to Change the Local Properties of Structure Components

This research deals with processes leading to local strengthening effects in Advanced High Strength Steels (AHSS). Dual phase (DP), retained austenite (RA) - both hot and cold rolled - and complex phase (CP) steels have been investigated to examine the effect of thermal and mechanical processing parameters on local properties. For this purpose, a method has been investigated to achieve local strengthening, namely local deformation and local heat treatment. Samples were locally deformed by bending and embossing processes. A local deformation with defined pre-strains leads to enhanced hardness and strengthening. A subsequent aging treatment leads to a further increase in mechanical properties. Local heat treatment was applied using a laser and an electron beam. Following local heat treatment with selected parameters, the microstructure of the surface and the cross section as well as the mechanical properties were evaluated by light optical, scanning as well as transmission electron microscopy, hardness measurement, tensile testing and thermal modelling. It can be stated that with partial heat treatment, local high strengthening can be produced. At lower heat treating temperatures, this effect could be attributed to bake hardening. With increased heat treating temperature, the initial microstructure near the surface is affected. A model can be improved, which defines the correlation between the influencing parameters and the local properties. The influence of over-aging in locally strengthen regions has been studied. For this investigation, parameters are stable to locally adjust the strengthening effect. Partial strengthening of AHSS by local deformation or local heat treatment can open up new fields of applications for locally using the strengthening effect to only influence relevant areas of interest, thus providing the potential for saving energy and designing the component’s behaviour.

Media and Gaúcho: Southern Brazilian – Identity

The subject of cultural identity has acquired a remarkable importance these days. On one hand, because of globalization and a possible trend toward cultural homogenization; on the other hand, because of the evident importance attained by regional and even national identities, in a local strengthening movement. The approach to national, regional, juvenile and gender identity as a communications study subject requires a more specific and complex understanding of these identities because their analysis extends to different social activities – especially the ones related to the media in a particular social environment. On an operational level, this involves the description and analysis of specific processes of identity formation which in this case are put together by the massive presence of different social networks made possible by communication technologies. The book Midia e Identidade Gaucha (Media and Gaucho southern Brazilian identity) is connected with those movements. For this reason it is relevant to rethink journalism practices, the consumption of music, the role of radio broadcasting, the representations put into circulation by the cinema, by TV, by the press, by websites, by comic strips and by advertising, as related to the gaucho way of life as this collection shows. Beyond the gaucho culture, the reports in this book bring up the question of constructing this gaucho identity through representations put into circulation by different media and/or symbolic practices. The existence of a diversity of narratives about this way of life is intrinsic to this conception and configures a cultural regime that lives through differences. From a conceptual standpoint, both the plurality of narratives and the existence of conflicts over the construction of the Media and Gaucho southern Brazilian – Identity

DINAMIKA OTONOMI DAERAH DALAM PENGEMBANGAN METODE PARTISIPASI PUBLIK PEMBENTUKAN PERATURAN PERUNDANG-UNDANGAN (2)

This article is taken from the research to study local democracy dynamic in regional autonomy transition, especially after the enactment of Law No. 32 of 2004 concerning on Regional Government and Law No 10 of 2004 concerning on Legislation Making. These laws have influenced the process of public policy making at field. This research analyse the implementation the word ’berhak’ (right to) as stipulated under article 53 of Law No. 10 of 2004. From this point of view, this continues by mapping the development strategy in making legislation at regional level, mainly by searching to what extend public participation processes would contribute at that level. In local political context, the research aims to study how political participation at local level fully involves citizen to take decision, especially connected to: First, economic democracy which is a participatory magement all citizen in productive assets and collective property rights. Second, politic pluralism democracy which is an understanding and sensitivity over pluralistic and locality aspects of the needs and aspirations any citizen in public policy making. The research method uses a non-doctrinal legal research, especially by emplying sociology of law and political economy of law. The result is written in descriptive-analytic model. The research only limits on the development of public participatory method, so then it would have critical points in reforming law and institution, especially to guarantee public participation rights. The recommendations are: First, the needs of key action and more participative for reforming all policies at regional level, by emphasizing through (1) state institution reconstruction which more guarantees citizen political participation; (2) the shifting from ‘top-down’ to ‘bottom up’ processes; (3) the empowerment of people (capacity building) and local institutional strengthening. Second, strengthening legal framework for public participation, either at legislation or regulation levels. The public participation initiative through regional regulation or to improve parliament mechanism order are important to develop public participation methods in local regulation making. Furthermore, The research needs to be followed up by studying deeply about how the legal framework to secure better should be formulated, especialy in responding public participation, either better procedural control or substantial control from public. This research contributes partly in providing possible models and [legal] formulations which are more responsive to the people needs and justice, also to strengthen democratization processes in local governance system.Keywords : Public Participations, Local Autonomy, Local Regulations

The Finite Element Analysis of the End Anchorage under Larger Prestressing Load in Rehabilitation Engineering

Anchorages are the most important structure in the bridge’s rehabilitation engineering under external prestressing load, whose stress distribution is complex, it is necessary to carry out a detailed and careful structure analysis of anchorages. The inspection and strengthening design of an extra-large Bridge in Dongpu of Guangzhou City was taken for the background in the paper, the longitudinal stress, transverse stress and vertical stress of the end anchorage were given before and after adding concrete block, through finite element analysis of the end anchorage under larger prestressing load and the results of calculation of the anchorage were analyzed, it was showed that the strengthened effect of the end anchorage had been very obvious after concrete block was added. At the same time it was found that there were still some deficiencies on the end anchorage after concrete was added and the suggestions of the local strengthening of the end anchorage were proposed. It is helpful and referenced for the design of similar anchorage.

Designing Local Properties of Constructional Elements by Local Use of Ageing Effects in Multiphase Steels

The investigations deal with processes leading to local effects of strengthening in multiphase steels, being characterized by good formability, continuous yielding, high strength and a strong bake hardening and ageing effect. Dual phase and complex phase steels are under investigation to examine the effect of thermo-mechanical processing parameters on local ageing ability and its use for designed properties. For this purpose local heat treatment by laser are studied, as well as stability of local ageing on the adjusted strength. A remarkable increase of the hardness in the heat treated zone was observed. Stability of the local strengthening effect could be confirmed. Partial heat treatment of multiphase steels by laser can open a new field of application for the local use of the strengthening effect to influence only relevant areas, thus giving potential for energy saving.

Typical and atypical development of functional human brain networks: insights from resting-state fMRI

Over the past several decades, structural MRI studies have provided remarkable insights into human brain development by revealing the trajectory of gray and white matter maturation from childhood to adolescence and adulthood. In parallel, functional MRI studies have demonstrated changes in brain activation patterns accompanying cognitive development. Despite these advances, studying the maturation of functional brain networks underlying brain development continues to present unique scientific and methodological challenges. Resting-state fMRI (rsfMRI) has emerged as a novel method for investigating the development of large-scale functional brain networks in infants and young children. We review existing rsfMRI developmental studies and discuss how this method has begun to make significant contributions to our understanding of maturing brain organization. In particular, rsfMRI has been used to complement studies in other modalities investigating the emergence of functional segregation and integration across short and long-range connections spanning the entire brain. We show that rsfMRI studies help to clarify and reveal important principles of functional brain development, including a shift from diffuse to focal activation patterns, and simultaneous pruning of local connectivity and strengthening of long-range connectivity with age. The insights gained from these studies also shed light on potentially disrupted functional networks underlying atypical cognitive development associated with neurodevelopmental disorders. We conclude by identifying critical gaps in the current literature, discussing methodological issues, and suggesting avenues for future research.

The architecture, kinematics, and lithospheric processes of a compressional intraplate orogen occurring under Gondwana assembly: The Petermann orogeny, central Australia

We ally aeromagnetic interpretation with constrained three-dimensional (3D) gravity inversion over the Musgrave Province in central Australia to produce a 3D architectural and kinematic model of the ca. 550 Ma compressional intraplate Petermann orogeny. Our model is consistent with structural, metamorphic, and geochronological constraints and crustal-scale seismic models. Aeromagnetic interpretation indicates that divergent thrusts at the margins of the province are cut by transpressional shear zones that run along the axis of the orogen. Gravity inversion indicates that the marginal thrusts are crustal-scale and shallow-dipping, but that the transpressional shear zones of the axial zone are more steeply dipping, and penetrate the crust-mantle boundary, accommodating offsets of 10–25 km. This thick wedge of mantle within the lower crust has been in isostatic disequilibrium for more than 500 Ma, and we suggest that this load may be supported by local lithospheric strengthening resulting from the emplacement of relatively strong lithospheric mantle within the relatively weak lower crust. Other orogenic processes inferred from the model include: probable inversion of relict extensional architecture; crustal-scale strain partitioning leading to strain accommodation by the vertical and lateral extrusion of relatively undeformed crustal blocks; and escape tectonics directed toward the relatively free eastern margin of the orogen. These processes are consistent with the concept that mechanical and thermal heterogeneities in the lithosphere, and the resulting feedbacks with deformation, are the dominant controls on intraplate orogenesis. This model also demonstrates that the architecture and kinematics of the Petermann orogeny require modifi cation of leading models of Gondwana assembly.

The architecture, kinematics, and lithospheric processes of a compressional intraplate orogen occurring under Gondwana assembly: The Petermann orogeny, central Australia

We ally aeromagnetic interpretation with constrained three-dimensional (3D) gravity inversion over the Musgrave Province in central Australia to produce a 3D architectural and kinematic model of the ca. 550 Ma compressional intraplate Petermann orogeny. Our model is consistent with structural, metamorphic, and geochronological constraints and crustal-scale seismic models. Aeromagnetic interpretation indicates that divergent thrusts at the margins of the province are cut by transpressional shear zones that run along the axis of the orogen. Gravity inversion indicates that the marginal thrusts are crustal-scale and shallow-dipping, but that the transpressional shear zones of the axial zone are more steeply dipping, and penetrate the crust-mantle boundary, accommodating offsets of 10–25 km. This thick wedge of mantle within the lower crust has been in isostatic disequilibrium for more than 500 Ma, and we suggest that this load may be supported by local lithospheric strengthening resulting from the emplacement of relatively strong lithospheric mantle within the relatively weak lower crust. Other orogenic processes inferred from the model include: probable inversion of relict extensional architecture; crustal-scale strain partitioning leading to strain accommodation by the vertical and lateral extrusion of relatively undeformed crustal blocks; and escape tectonics directed toward the relatively free eastern margin of the orogen. These processes are consistent with the concept that mechanical and thermal heterogeneities in the lithosphere, and the resulting feedbacks with deformation, are the dominant controls on intraplate orogenesis. This model also demonstrates that the architecture and kinematics of the Petermann orogeny require modification of leading models of Gondwana assembly.