Level Of Energy Dissipation Research Articles

Analysis of timber log-house construction system via experimental testing and analytical modelling

The paper presents the outcome of a research on the in-plane behaviour of two different log house construction systems when subjected to lateral loading. Such systems, identified by the way the logs are joined together are: the Standard half lapped joint (ST) system and Tirolerschloss joint (TR) system. Two stages of experimental testing were carried out at the laboratory of the University of Trento. In the first stage the focus was on the corner joints and on a possible wall reinforcement system (22 monotonic and 5 cyclic tests were performed). In the second stage full-scale wall specimens were tested (5 monotonic and 5 cyclic tests). Several layouts were investigated: 4.2m long walls with thin (TR and ST) or thick logs (ST); “short” walls (2.75m long); walls with openings.The test results highlighted some critical aspects in the in-plane behaviour of the walls. The lateral load carrying capacity of the wall appeared to be influenced by two main phenomena: friction and corner-joint interlocking. Due to mounting tolerance a large displacement was required to fully engage the corner joint resistance. A large horizontal plateau characterized the post friction part of the load displacement curve (wide plateau) both for ultimate limit state (ULS) and serviceability limit state (SLS). The cyclic tests showed a high level of energy dissipation that was attributed to the “inter-log friction”. In order to have a better insight into such aspects, a simplified rheological/analytical model was developed by using the experimental data as input parameters. A good agreement between the model output and the experimental behaviour was obtained.

Estimates of tidal mixing in the Indonesian archipelago from multidisciplinary INDOMIX in-situ data

The Indonesian Mixing program (INDOMIX) was designed to quantify the very strong mixing that transforms Pacific waters into isohaline Indonesian Waters in the Indonesian archipelago. The turbulent dissipation rates and associated mixing were estimated and analyzed using a multidisciplinary approach that combines physical and geochemical in-situ observations: (1) direct measurements of the dissipation using a microstructure profiler, (2) use of density-based fine-scale methods applied to CTD and XCTD data, and (3) study of the vertical distribution of natural radionuclides (radium isotopes and actinium-227). Data were collected at five contrasting stations within the Indonesian archipelago, found above energetic straits or in relatively quiescent large basins.Strong instabilities, inversions of the density profiles and a very strong water mass transformation were observed. A wide range of dissipation values were obtained (between [10−10, 10−4]Wkg−1) with spots of higher dissipation in the ocean interior correlated with a strong internal tide signal. Both the fine-scale and micro-scale methods allow us to identify very strong energy dissipation levels above the straits, ranging between [10−7, 10−4]Wkg−1, in contrast to lower values at stations further away from the generation sites. The dissipation for the station located in the center of the Halmahera Sea ([10−9, 10−8]Wkg−1) is stronger than for the Banda station ([10−11, 10−10]Wkg−1), which is even further away from the generation sites. The three approaches agree relatively well and provide vertical eddy diffusivities values ranging between 5×10−4 and 5×10−1m2s−1, except in the Banda Sea where values are similar to the ones found in the open ocean (10−6m2s−1). CTD and XCTD profilers (deployed between stations) give estimates of dissipation all along the transit. It is found that enhanced mixing occurs preferentially above rough topography, such as in the Ombai Strait, the Halmahera Sea’s northern entrance, the Buru strait and Sumba strait.Finestructure parameters are very sensitive to depth and dissipation, which differs between stations. We recommend more systematic microstructure measurement in order to tune these parameters. Surface mixing, at the base of the mixed layer is found to be very strong with values between [10−4, 10−3m2s−1]. These results confirm the modeling studies that suggest the occurrence of intensified subsurface mixing which cools the sea surface temperatures and thus strongly affects the mean and variability of the tropical climate. We conclude, therefore, that climate models need to take into account this intensified ocean mixing to properly represent the mean state of the atmosphere and its climate variability.

Aseismic smart building isolation systems under multi-level earthquake excitations: Part II, energy-dissipation and damage reduction

Based on the performance results of the previously suggested smart building isolation systems (1st companion paper), this following study verifies the control effects of the systems from the view point of energy dissipation and damage level metrics. Several different model cases of the strategically isolated multi-story building structures utilizing passive dampers and semi-active resettable devices are analyzed and the energy-based target indices are compared. Performance comparisons are conducted on statistically calculated story/structural hysteretic energy and story/structural damage demands over realistic suites of earthquake ground motion records, representing seismic excitations of specific return period probability. Again, the semi-active solutions show significant promise for applications of resettable device, offering advantages over passive systems in the consistent damage reductions. The specific results of this study include the identification of differences in the mechanisms by which smart building isolation systems remove energy, based on the differences in the devices used. Less variability is also seen for the semi-active isolation systems, indicating an increased robustness.

Seismic Performance of Full-Scale Post-Tensioned Timber Beam-Column Connections

Structural frames made of prefabricated laminated timber beams and columns connected by unbonded post-tensioning and additional mild steel reinforcement have recently been proposed for multi-story timber buildings. The benefits of post-tensioning to assemble prefabricated timber elements are rapid erection, simple connections, and high seismic resistance. It has been shown that prefabricated post-tensioned timber members can be designed to have excellent seismic resistance, with the post-tensioning providing re-centering capacity after major earthquakes, while energy is dissipated through yielding of replaceable mild steel devices.This article summarizes the results of an investigation into the seismic response of full-scale timber beam-column joints, subjected to extensive experimental study and numerical modelling, performed as part of a larger research program on timber structures at the University of Canterbury, New Zealand. The beams and columns were fabricated from laminated veneer lumber (LVL). The tested joint was designed as part of a moment-resisting frame for a six-story building located in a high-seismic region. The timber members and the re-centering/dissipating elements were optimized to produce the intended dissipating-recentering behavior and commercially available prestressing arrangements were used to verify their applicability in a timber structure.The results of the experiments on both interior and exterior beam-column joints are presented, for both post-tensioned-only and hybrid models. The post-tensioned-only solutions exhibited nonlinear elastic behavior with full re-centering while the hybrid systems provided significantly greater levels of energy dissipation compared with the post-tensioned-only solution. The joints were also tested with a number of additional features such as steel armoring plates at the interface, reinforcement in the form of long screws embedded into the column and combination of the two. The armored the column faces with steel plates exhibited higher stiffness and smaller deformation in compression perpendicular to the grain. The joint region within reinforced column reduce the subsequent drop in prestressing forces in the system. Combination of armoring and reinforcements protect the joint region through minimizing joint shear panel deformation. In general, the tested arrangements exhibited high levels of ductility and negligible residual deformations with no significant damage of the structural elements. The numerical models accurately predict the behavior of different types of beam-column joints tested and can be used to design similar connections. These full-scale tests also demonstrate the practical feasibility of post-tensioned timber frames for multi-story timber buildings.

Limiting values of slenderness ratio for circular braces of concentrically braced frames

Special concentrically braced frames (SCBFs) are commonly used to resist lateral forces in the structures located in high-seismic regions. Steel braces of SCBFs are expected to undergo large inelastic axial deformations in order to provide an adequate level of structural ductility and hysteretic energy dissipation under cyclic loading. The energy dissipation capacity and ductility of SCBFs largely depend on the slenderness ratio and width-to-thickness ratio of braces. The main objective of this study is to find an optimum range of these parameters for braces of hollow circular steel (HCS) sections in order to achieve the enhanced seismic performance of SCBFs. A finite element (FE) study has been conducted on a wide range of values of these parameters using a software package ABAQUS. The FE models account for the inelastic hysteretic characteristics and the fracture behaviour of braces. The results of simulation models matched very well with the past experimental results with respect to the performance points, namely, global buckling, local buckling, fracture initiation, and complete fracture. Finally, a relationship has been established between the slenderness ratio and the width-to-thickness of HCS braces based on the simulation results.

A NOVEL APPROACH TO TRACE SHORTEST PATH IN AIR FORCE USING DIJKSTRA’S ALGORITHM

The nodes in ad-hoc networks are battery operated and have limited energy resources. This makes energy efficiency a key concern in ensuring system longevity. It is desirable to keep the energy-dissipation level as low as possible to avoid frequent battery replacement. Energy conservation has posed a big challenge due to MANETs' nature of distributed control, constantly changed network topology and the fact that mobile nodes in MANETs usually are hand-held devices. In this paper I have proposed the new approach for energy conservation using relay nodes. Results demonstrate that the new approach has performed well in energy conservation.

Energy Conservation using Relay nodes

- The nodes in ad-hoc networks are battery operated and have limited energy resources. This makes energy efficiency a key concern in ensuring system longevity. It is desirable to keep the energy-dissipation level as low as possible to avoid frequent battery replacement. Energy conservation has posed a big challenge due to MANETs' nature of distributed control, constantly changed network topology and the fact that mobile nodes in MANETs usually are hand-held devices. In this paper I have proposed the new approach for energy conservation using relay nodes. Results demonstrate that the new approach has performed well in energy conservation.

Examining the photoprotection hypothesis for adaxial foliar anthocyanin accumulation by revisiting comparisons of green- and red-leafed varieties of coleus (Solenostemon scutellarioides)

Although plants rely on light to drive energy production via photosynthesis, excess light can be harmful. Plants have evolved photoprotective mechanisms to mitigate this threat, including thermal energy dissipation, the most common form of which involves de-epoxidized constituents of the xanthophyll cycle facilitating the conversion of excess excitation energy to heat. A role in photoprotection has also been proposed for red anthocyanins when they accumulate near the adaxial leaf surface. Here, we compared the response to experimental light stress of a red-leafed (anthocyanin rich) and a green-leafed variety of coleus [Solenostemon scutellarioides (L.) Codd], examining chlorophyll fluorescence emission and pigment composition. After experimentally imposed intense white light, red- and green-leafed coleus exhibited manifestations of light stress (decreased photosystem II quantum efficiency) of a similar magnitude. This, considered alone, could be interpreted as evidence that anthocyanins do not serve a photoprotective role. However, during excess light exposure, the green-leafed variety employed a greater level of thermal energy dissipation and possessed correspondingly higher xanthophyll cycle pool sizes and de-epoxidation states. During exposure to red light, which anthocyanins absorb very poorly, levels of thermal energy dissipation did not differ between coleus varieties. Taken together, our findings suggest that adaxial anthocyanins minimize stress associated with excess light absorption and that the green-leafed variety of coleus compensated for its much lower levels of adaxial anthocyanins by invoking higher levels of energy dissipation. Thus, anthocyanin accumulation should be considered alongside the suite of photoprotective mechanisms employed by photosynthetic tissues.

Chloroplast thylakoid structure in evergreen leaves employing strong thermal energy dissipation

In nature, photosynthetic organisms cope with highly variable light environments – intensities varying over orders of magnitudes as well as rapid fluctuations over seconds-to-minutes – by alternating between (a) highly effective absorption and photochemical conversion of light levels limiting to photosynthesis and (b) powerful photoprotective thermal dissipation of potentially damaging light levels exceeding those that can be utilized in photosynthesis. Adjustments of the photosynthetic apparatus to changes in light environment involve biophysical, biochemical, and structural adjustments. We used electron micrographs to assess overall thylakoid grana structure in evergreen species that exhibit much stronger maximal levels of thermal energy dissipation than the more commonly studied annual species. Our findings indicate an association between partial or complete unstacking of thylakoid grana structure and strong reversible thermal energy dissipation that, in contrast to what has been reported for annual species with much lower maximal levels of energy dissipation, is similar to what is seen under photoinhibitory conditions. For a tropical evergreen with tall grana stacks, a loosening, or vertical unstacking, of grana was seen in sun-grown plants exhibiting pronounced pH-dependent, rapidly reversible thermal energy dissipation as well as for sudden low-to-high-light transfer of shade-grown plants that responded with photoinhibition, characterized by strong dark-sustained, pH-independent thermal energy dissipation and photosystem II (PSII) inactivation. On the other hand, full-sun exposed subalpine confers with rather short grana stacks transitioned from autumn to winter via conversion of most thylakoids from granal to stromal lamellae concomitant with photoinhibitory photosynthetic inactivation and sustained thermal energy dissipation. We propose that these two types of changes (partial or complete unstacking of grana) in thylakoid arrangement are both associated with the strong non-photochemical quenching (NPQ) of chlorophyll fluorescence (a measure of photoprotective thermal energy dissipation) unique to evergreen species rather than with PSII inactivation per se.

System-Level Displacement- and Performance-Based Seismic Design Parameter Quantifications for an Asymmetrical Reinforced Concrete Masonry Building

AbstractThis paper focuses on analyzing the performance of structural walls comprising the seismic force resisting system (SFRS) in a scaled asymmetrical fully grouted reinforced masonry (RM) building tested under quasi-static loading. The in-plane tensile and compressive strains calculated at the wall toes and the curvature profile along the wall height as well as the contributions of the flexural and the shear deformations to the overall wall displacements were quantified. The component-level (when the walls were tested individually) responses were compared with those at the system level (in a building). In addition, key input parameters for displacement-based seismic design approaches, including stiffness degradation and the trend of the building’s effective period increase as well as the variation of hysteretic damping, were quantified. Moreover, the building energy dissipation levels were compared with those generated during the individual wall tests to quantify the contribution of each component to ...

The Impact of Finite-Amplitude Bottom Topography on Internal Wave Generation in the Southern Ocean

Abstract Direct observations in the Southern Ocean report enhanced internal wave activity and turbulence in a kilometer-thick layer above rough bottom topography collocated with the deep-reaching fronts of the Antarctic Circumpolar Current. Linear theory, corrected for finite-amplitude topography based on idealized, two-dimensional numerical simulations, has been recently used to estimate the global distribution of internal wave generation by oceanic currents and eddies. The global estimate shows that the topographic wave generation is a significant sink of energy for geostrophic flows and a source of energy for turbulent mixing in the deep ocean. However, comparison with recent observations from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean shows that the linear theory predictions and idealized two-dimensional simulations grossly overestimate the observed levels of turbulent energy dissipation. This study presents two- and three-dimensional, realistic topography simulations of internal lee-wave generation from a steady flow interacting with topography with parameters typical of Drake Passage. The results demonstrate that internal wave generation at three-dimensional, finite bottom topography is reduced compared to the two-dimensional case. The reduction is primarily associated with finite-amplitude bottom topography effects that suppress vertical motions and thus reduce the amplitude of the internal waves radiated from topography. The implication of these results for the global lee-wave generation is discussed.

Effects of enhanced UV radiation and water availability on performance, biomass production and photoprotective mechanisms of Laurus nobilis seedlings

Climate models predict an increase in ultraviolet (UV) radiation and a reduction in precipitation in the Mediterranean region in the coming decades. High levels of UV radiation and water shortage can both cause photo-oxidative stress in plants. The aim of this study was to investigate the effects of enhanced UV radiation and its interaction with low water availability on seedling performance, biomass production, and photoprotective mechanisms of the sclerophyllous evergreen species Laurus nobilis L. (laurel). To achieve this goal, one-year-old seedlings of L. nobilis were grown outdoors under three UV conditions (ambient UV, enhanced UV-A, and enhanced UV-A+UV-B) and under two watering regimes (watered to field capacity and reduced water supply). The results show that plants produced more biomass when exposed to above ambient levels of UV-A or UV-A+UV-B radiation, especially under low water availability. This was probably related to a UV-induced increase in leaf relative water content and in leaf water use efficiency under water shortage. Even though our results suggest that UV-A supplementation may play an important role in the stimulation of biomass production, plants grown under enhanced UV-A plots showed higher levels of energy dissipation as heat (measured as NPQ) and a higher de-epoxidation state of the violaxanthin cycle. This suggests a greater excess of light energy under UV-A supplementation, in accordance with the observed reduction in the foliar content of light-absorbing pigments in these plants. Strikingly, the addition of UV-B radiation mitigated these effects. In conclusion, UV enhancement might benefit water status and growth of L. nobilis seedlings, especially under low water availability. The results also indicate the activation of different plant response mechanisms to UV-A and UV-B radiation, which would interact to produce the overall plant response.

Seismic demand on steel reinforcing bars in reinforced concrete frame structures

Modern design standards for reinforced concrete (r.c.) buildings allow the achievement of ductile structures, able to globally dissipate seismic energy through the development of plastic deformations located in the dissipative regions (i.e. plastic hinges). The hysteretic capacity of r.c. structures is related to the ability of reinforcing steel bars to sustain many cycles of high plastic deformations without the exhibition significant decrease of strength and stiffness; this condition, typically due to cyclic/seismic action, shall be widely investigated in order to obtain a full and detailed knowledge of the structural behaviour of modern r.c. buildings. In the present paper, elaborated inside the European research project “Rusteel”, the evaluation of the seismic ductile demand on steel reinforcing bars due to real earthquake events was carried out. Representative r.c. case study buildings were designed following the actual European and Italian prescriptions and analyzed using the Incremental Dynamic Analysis technique for the assessment of the behaviour under real seismic events. The elaboration of a simplified mechanical model for the steel reinforcing bars, calibrated on the basis of experimental monotonic and cyclic tests, allowed the evaluation of the effective level of deformation and energy dissipation required by earthquakes and the assessment of the ability of the actual European production to satisfy the effective seismic ductile requirements.

The role of energy dissipation of polymeric scaffolds in the mechanobiological modulation of chondrogenic expression

Mechanical stimulation has been proposed to induce chondrogenesis in cell-seeded scaffolds. However, the effects of mechanical stimuli on engineered cartilage may vary substantially between different scaffolds. This advocates for the need to identify an overarching mechanobiological variable. We hypothesize that energy dissipation of scaffolds subjected to dynamic loading may be used as a mechanobiology variable. The energy dissipation would furnish a general criterion to adjust the mechanical stimulation favoring chondrogenesis in scaffold. Epiphyseal chondro-progenitor cells were then subject to unconfined compression 2 h per day during four days in different scaffolds, which differ only by the level of dissipation they generated while keeping the same loading conditions. Scaffolds with higher dissipation levels upregulated the mRNA of chondrogenic markers. In contrast lower dissipation of scaffolds was associated with downregulation of chondrogenic markers. These results showed that energy dissipation could be considered as a mechanobiology variable in cartilage. This study also indicated that scaffolds with energy dissipation level close to the one of cartilage favors chondrogenic expression when dynamical loading is present.

Does centennial morphodynamic evolution lead to higher channel efficiency in San Pablo Bay, California?

Abstract Measured bathymetries on 30 year interval over the past 150 years show that San Pablo Bay experienced periods of considerable deposition followed by periods of net erosion. However, the main channel in San Pablo Bay has continuously narrowed. The underlying mechanisms and consequences of this tidal channel evolution are not well understood. The central question of this study is whether tidal channels evolve towards a geometry that leads to more efficient hydraulic conveyance and sediment throughput. We applied a hydrodynamic process-based, numerical model (Delft3D), which was run on 5 San Pablo Bay bathymetries measured between 1856 and 1983. Model results shows increasing energy dissipation levels for lower water flows leading to an approximately 15% lower efficiency in 1983 compared to 1856. During the same period the relative seaward sediment throughput through the San Pablo Bay main channel increased by 10%. A probable explanation is that San Pablo Bay is still affected by the excessive historic sediment supply. Sea level rise and Delta surface water area variations over 150 years have limited effect on the model results. With expected lower sediment concentrations in the watershed and less impact of wind waves due to erosion of the shallow flats, it is possible that energy dissipations levels will decrease again in future decades. Our study suggests that the morphodynamic adaptation time scale to excessive variations in sediment supply to estuaries may be on the order of centuries.

Braking performance and influence of microstructure of advanced cast irons for heavy goods vehicle brake discs

It is well known that truck brakes dissipate several megajoules of energy every few seconds, which leads to high thermal stresses in the rubbing parts. Therefore, premature failure by cracking of truck brake discs is a matter of major concern. Improving the design and material of brake discs may enhance braking performance. This study focuses on the latter aspect and was carried out with the aim of developing new material solutions for increasing disc lifespan. To do so, braking experiments were conducted on a specially designed braking tribometer. The brake pads that were used were made from a commercial brake lining material. Two advanced cast irons with different graphite morphology were studied in comparison with the lamellar grey cast iron commonly used for brake disc. To verify the friction and thermal behaviour of the two cast irons, braking tests were carried out as a series of stop-brakings with increasing dissipated power and energy and as a series of slowdowns to achieve heat accumulation effects. Thermal phenomena were studied through bulk temperature measurements and infrared monitoring of the disc surface. Friction behaviour, braking performance and variations in thermal loading were analysed in relation to the level of energy dissipation. The two advanced cast irons and lamellar cast iron had equivalent braking performance and stored similar amounts of heat, according to their thermophysical properties. Observations of the rubbing surfaces indicated damage mechanisms affected by the graphite morphology. Less plastic deformation on the surface was observed with an interdendritic graphite.

Feasibility study of a gap damper to control seismic isolator displacements in extreme earthquakes

SUMMARY Base isolation systems generally perform well under design-level ground motions to reduce both interstory drift and acceleration demands. During a maximum considered earthquake, however, large displacements in the base level may cause pounding between the structure and perimeter moat wall, which can lead to very high acceleration in the superstructure. A phased passive control device, or ‘gap damper’, has been conceived to control base isolator displacement during extreme events while having no effect on the isolation system performance for earthquakes up to design level. It is by introducing an appropriate initial gap that the device triggers additional energy dissipation during large earthquakes to limit displacements. Various combinations of hysteretic and viscous damping mechanisms are utilized to provide desired additional energy dissipation. A numerical study that assesses the ability of various gap damper models to reduce the base displacement by at least 25% while limiting the acceleration increase at the roof level that results from the sudden engagement of a damping device is devised. The energy dissipation level provided by the damper is optimized to provide the best possible performance. For base isolation systems with effective periods of isolation in the 2.5–3.0 s range, gap damper models incorporating a viscous dashpot are very effective in controlling displacement, whereas gap dampers restricted to a hysteretic damping mechanism are ineffective. The gap damper is less effective for systems with longer periods of isolation (3.5–4.0 s) because the lower target acceleration in this range is more difficult to meet. Copyright © 2012 John Wiley & Sons, Ltd.

드롭랜딩 시 높이 변화에 따른 인체 분절의 충격흡수 전략에 관한 연구

The purpose of current study was to investigate the effects of the heights on the lower extremities, torso and neck segments for energy dissipation during single-leg drop landing from different heights. Twenty eight young healthy male subjects(age: <TEX>$23.21{\pm}1.66yr$</TEX>, height: <TEX>$176.03{\pm}4.22cm$</TEX>, weight: <TEX>$68.93{\pm}5.36kg$</TEX>) were participated in this study. The subjects performed the single-leg drop landing from the various height(30, 45 & 60 cm). Force plates and motion-capture system were used to capture ground reaction force and kinematics data, respectively. The results were as follows. First, the ROM at the ankle, knee, hip and trunk was increased with the increased heights but the ROM at the neck was increased in the 60cm. Second, the angular velocity, moment and eccentric work at the ankle, knee, hip, trunk, and neck was increased with the increased heights. Third, the contribution to total work at the knee joint was not significantly different, while the ankle joint rate was decreased and hip and neck rate was increased in the 60cm, and trunk rate was increased with the increased heights. Lastly, the increase in landing height was able to augment the level of energy dissipation not only at the lower extremities but also at the trunk and neck. The findings showed that drop landing affect trunk and neck with lower extremity joints. Therefore, we need to consider that trunk and neck strengthening including stability should be added to reduce sports injury during prevention training.

The dynamics of an energetic tidal channel, the Pentland Firth, Scotland

Shelf tidal stream velocities are accelerated by nearshore geographic features, such as headlands and islands. In the search for sustainable forms of electrical energy generation, such locations may become attractive for tidal stream power developments. For some prospective tidal stream energy sites, however, little is known about the intricacies of the local tidal dynamics: knowledge which is crucial to the understanding of the resource and the potential environmental consequences of its extraction.In this paper a two dimensional hydrodynamic model is used to investigate a complex tidal strait, the Pentland Firth (Scotland, UK). This channel, considered one of the most promising tidal stream energy sites in the world, is set for extensive development over the coming decade. We show that the tidal stream velocities that regularly occur within, and up to 20-km beyond the Pentland Firth, are accelerated above that of a free shallow-water wave. The primary mechanism for these accelerations is hydraulic in nature, associated with a large shift in tidal phase. Tidal streaming around headlands and islands further promotes conversion from potential to kinetic energy. We calculate a mean energy flux into the Pentland Firth from the North Atlantic Ocean of 8.97GW. Changes in tidal amplitude and phase along the strait are associated with a reduction in energy flux, such that the majority (∼60%) of the incoming energy is lost within the Pentland Firth through bed friction.Localised geographical factors complicate the tidal dynamics of the Pentland Firth, therefore detailed modelling is the only means with which to accurately characterise the environmental conditions in this channel. Of more general oceanographic significance, this example shows that high levels of tidal energy dissipation are associated with energetic tidal straits. Energy losses in these straits may contribute significantly to balancing the energy flux onto the continental shelf from the deep seas.

Advanced Materials for Transportation Euromat 2011

The present special issue of Steel Research International is based on Symposium E31. Advanced Materials for Transportation, organized as part of the 2011 European Congress and Exhibition on Advanced Materials and Processes (Euromat 2011) held in Montpellier from September 12th to 15th, 2011. The Euromat conferences together form a long-established series of large materials science and engineering events under the auspices of the Federation of European Materials Societies (FEMS), a series which is unequalled in size and scope in Europe except for the annual E-MRS Spring Meeting. Materials in transportation itself is a topic as wide as materials science in general. It encompasses structural as well as functional materials for a multitude of applications, the more so since transportation itself literally extends from sea to space, and covering all that's in between, too – not the least the automotive sector. The latter has recently endeavored to further increase the range of materials associable with transportation by heavily investigating alternative propulsion, and specifically the electric drive. Thus from coils to batteries, a lot is added. As a result of this diversity, the present issue of Steel Research International is somewhat unique, as it extends far beyond steel: Taking the automotive sector as example, steel is still the dominant structural material, and it is not unlikely to maintain this position despite competition from several other classes of materials. One may ask how this is possible. Surely, the pressure exerted on the industry first by aluminum based solutions and nowadays by a possible advent of carbon fiber reinforced composites as materials of choice for the automotive body have fuelled new efforts in research. Over recent years, these efforts have yielded fascinating new materials and processes like TRIP or TWIP steels combining ever-increased strength with great ductility. In conclusion, one might thus come to think that what serves the development of steel best – and obviously this is an observation that is not restricted to the field of materials engineering – is strong alternatives. The present issue of Steel Research International casts spotlights on some such competitors. These include polymer as well as metal matrix composites, metallic foams, and hybrid solutions combining, in new ways, FRP and metal for structural applications, while nickel and titanium are considered where structural and functional requirements meet and additional boundary conditions such as elevated temperatures have to be addressed. Steel enters this wider picture in a study on fatigue of spot welds in advanced high strength steels. The issue's spotlight character is due to the fact that we present selected contributions here from a conference symposium that offered an altogether wider scope. Nevertheless, we are confident that the final selection should find the interest the work of the authors clearly deserves. We would like to take this opportunity to thank them for their part in realizing both symposium and this present journal issue. We would furthermore like to extent this expression of our gratitude to all the referees involved in the peer review process, and not the least to the editorial team of Steel Research International for supporting us in putting together what you, as reader, hold in your hands now. Euromat 2013, which will be held in Sevilla from September 8th to 13th, will see a continuation of our symposia series, which originally dates back to Euromat 2009. We have decided on some minor changes, though: While we had exceedingly broad symposia in the past, we will now focus our activities in separate sub-events on lightweight, energy absorbing, and hybrid materials and structures. A link between these will be provided by a fourth symposium on modeling, simulation, and optimization. Steel will remain central as a material of outstanding versatility and width of property ranges, be it for lightweight design, or for achieving highest levels of energy dissipation to improve crashworthiness. We encouraged all readers of this special issue to watch out for this future event – and contribute if they like, as authors or as partners in discussion.