Large Structural Elements Research Articles

Onshore–offshore potential field analysis of the Møre–Trøndelag Fault Complex and adjacent structures of Mid Norway

The Møre–Trøndelag Fault Complex (MTFC) is one of the most prominent fault complexes of Scandinavia. It exerted a strong control on the development of offshore basins of Mid Norway and onshore topography. However, the relationships between the faults observed in the field onshore and those identified by means of seismic profiling offshore remain obscure. Regional gravity and aeromagnetic data are used to map regional-scale faults and, in particular, to delineate the main geophysical features related to the MTFC. The advantage of potential field data is to provide an almost continuous coverage and to tie bedrock mapping onshore to seismic interpretation offshore. In this paper, we apply potential field transformations to focus on the regional and deep-seated structures in order to extract new geological information. Also the tilt derivative technique (TDR) is applied to gravity and magnetic data with the aim of enhancing linear trends. The results indicate the possible onshore–offshore links of large scale structural elements like the MTFC and late-Caledonian detachments (e.g. Kollstraumen Detachment). The locations of different segments of the MTFC are detected and possible new faults/lineaments are depicted. Correlating petrophysical data with gravity and magnetic maps explains the influence of the MTFC on the deformation and mineralisation of bedrock along its strike. In addition, the structural pattern seen in the enhanced lineaments is diagnostic for the sinistral strike–slip movements that are known to have occurred in Devonian time along the MTFC. This confirms the important role of the MTFC in the tectonic setting and geological evolution of Mid Norway.

Simulated evolution of the dark matter large-scale structure of the Universe

We analyze evolution of the basic properties of simulated large scale structure elements formed by dark matter (DM LSS) and confront it with the observed evolution of the Lyman-$\alpha$ forest. In three high resolution simulations we selected samples of compact DM clouds of moderate overdensity. Clouds are selected at redshifts $0\leq z\leq 3$ with the Minimal Spanning Tree (MST) technique. The main properties of so selected clouds are analyzed in 3D space and with the core sampling approach, what allows us to compare estimates of the DM LSS evolution obtained with two different techniques and to clarify some important aspects of the LSS evolution. In both cases we find that regular redshift variations of the mean characteristics of the DM LSS are accompanied only by small variations of their PDFs, what indicates the self similar character of the DM LSS evolution. The high degree of relaxation of DM particles compressed within the LSS is found along the shortest principal axis of clouds. We see that the internal structure of selected clouds depends upon the mass resolution and scale of perturbations achieved in simulations. It is found that the low mass tail of the PDFs of the LSS characteristics depends upon the procedure of clouds selection.

On the Use of Gas Metal Arc Welding for Manufacturing Beams of Commercially Pure Titanium and a Titanium Alloy

A noticeable reduction in the cost of structural components made from titanium, both commercially pure and the alloy counterpart is possible with the concept of built-up welded fabrication. Rolled sheets of the titanium material can be welded together to fabricate a built-up structural component without having to machine the part from a large billet. In this paper, the results of a recent feasibility study on the manufacturing of welded built-up I-beams for large structural applications are presented and discussed. The fillet welds were produced using the pulsed Gas Metal Arc Welding (GMAW-P) process. Commercially pure titanium (Grade 2) and a titanium alloy (Ti-6Al-4 V) were the two materials chosen for the study. The specific details of the welding process are highlighted along with a discussion of the successful implementation of the concept of built-up welded beams for the manufacture of large structural elements and components of titanium.

Structural and kinematic assemblies in sedimentary rocks of the Phanerozoic cover of the Mid-Russian Dislocation Zone

The Mid-Russian Dislocation Zone is a large within-plate structural element of the East European Platform, which extends for more than 1100 km from the Timan Foredeep to the Orsha Basin. This deep, long-lived zone was formed against a background of changeable geodynamic settings, including (1) Late Paleoproterozoic collision events, (2) Late Riphean-Early Vendian epicontinental rifting, (3) Late Vendian-Early Triassic intraplatform tectogenesis with formation of horst-like uplifts within the zone against the background of general subsidence, and (4) Mesozoic-Cenozoic within-plate reactivation. At the final Kimmerian-Alpine stage of its evolution, the Mid-Russian Zone developed as a left-lateral transpressional structure with penetrative dissipative shear deformation resulting in the general horizontal transfer of Phanerozoic sedimentary rocks. The dislocations were manifested as two dynamically conjugate structural forms: a zone of scattered shearing and a bedding-plane tectonic flow. The dynamic manifestation of the Mid-Russian and the conjugate Belomorian-Dvina zones, which make up a common arcuate structure (in plan view), allowed us to outline the Dvina-Sukhona plate-flow with horizontal mass transfer in the southeastern direction. The tectonics of the Mid-Russian Dislocation Zone is considered in this paper with particular emphasis on the structural and kinematic assemblies in sedimentary rocks of the Phanerozoic cover.

Estimation of wave forces on large compliant platforms

Compliant offshore structures such as spars, tension leg platforms (TLPs) and semi-submersibles have been dramatically improved in recent years due to their capability for deep water operation. Waves are the most important environmental phenomenon affecting these offshore structures. Estimation of wave forces is vital in offshore structure design. For large compliant offshore platforms, Morrison’s equation is not valid anymore and usually diffraction theory is used. In this research, by using the finite difference method, a detailed analysis of the first-order diffraction of monochromatic waves on a large cylinder as a structural element is performed to solve the radiation and diffraction potentials. The results showed that the developed model is a reliable tool to estimate the wave forces and hydrodynamic coefficients on large structure elements when wave diffraction and radiation are considered.

Artificial Chemokines: Combining Chemistry and Molecular Biology for the Elucidation of Interleukin-8 Functionality

How can we understand the contribution of individual parts or segments to complex structures? A typical strategy to answer this question is simulation of a segmental replacement followed by realization and investigation of the resulting effect in structure-activity studies. For proteins, this problem is commonly addressed by site-directed mutagenesis. A more general approach represents the exchange of whole secondary structure elements by rationally designed segments. For a demonstration of this possibility we identified the alpha-helix at the C-terminus of human interleukin-8 (hIL-8). Since this chemokine possesses four conserved cysteine residues, it can easily be altered by ligation strategies. A set of different segments, which are able to form amphiphilic helices, was synthesized to mimic the C-terminal alpha-helix. Beside sequences of alpha-amino acids, oligomers of non-natural beta(3)-amino acids with the side chains of canonical amino acids were introduced. Such beta-peptides form helices, which differ from the alpha-helix in handedness and dipole orientation. Variants of the semisynthetic hIL-8 proteins demonstrated clearly that the exact side chain orientation is of more importance than helix handedness and dipole orientation. The activity of a chimeric protein with a beta-peptide helix that mimics the side chain orientation of the native alpha-helix most perfectly is comparable to that of the native hIL-8. Concepts like this could be a first step toward the synthesis of proteins consisting of large artificial secondary structure elements.

High Frequency Testing Facility for Stay Cables and Tendons

Fatigue is an important cause of failure in mechanical components and structures that are subjected to repeated loads. The testing of structural components under cyclic loading constitutes one of the most important fields of experimental mechanics. The testing of specimens with 2 to 20 million load cycles is only feasible for small specimens, and not for large structural elements. Usually, conventional servo-hydraulic testing machines are used; thus, time to carry out the experiments as well as the energy consumption increase dramatically with specimen size. A new approach to the testing of large structural elements by taking advantage of the resonance effect is shown in this paper. For example, a fatigue experiment on a stay cable for a bridge takes 3 to 4 weeks by using conventional servo hydraulic controlled jacks. The approach developed at the Institute for Structural Engineering at Vienna University of Technology reduces testing periods by a factor of 20 to 50 and the required energy input for a fatigue test by a factor of more than 1000. A testing unit dimensioned for a static tensile load up to 20 000 kN and an upper load for fatigue tests up to 10 000 kN was built at the Vienna University of Technology in 2006.

Polypyrimidine-tract-binding protein: a multifunctional RNA-binding protein

PTB (polypyrimidine-tract-binding protein) is a ubiquitous RNA-binding protein. It was originally identified as a protein with a role in splicing but it is now known to function in a large number of diverse cellular processes including polyadenylation, mRNA stability and translation initiation. Specificity of PTB function is achieved by a combination of changes in the cellular localization of this protein (its ability to shuttle from the nucleus to the cytoplasm is tightly controlled) and its interaction with additional proteins. These differences in location and trans-acting factor requirements account for the fact that PTB acts both as a suppressor of splicing and an activator of translation. In the latter case, the role of PTB in translation has been studied extensively and it appears that this protein is required for an alternative form of translation initiation that is mediated by a large RNA structural element termed an IRES (internal ribosome entry site) that allows the synthesis of picornaviral proteins and cellular proteins that function to control cell growth and cell death. In the present review, we discuss how PTB regulates these disparate processes.

Riphean stromatolitic formations fringing the East European platform

Riphean stromatolitic formations flank the East European epi-Karelian platform only in the east and northeast. They are traceable as long (over 3600 km) relatively narrow belt consisting of two rectilinear segments, one running along the Urals western flank from southern extremity of the Bashkirian meganticlinorium to the Polyudov Ridge and the other one extending from the southern and central Timan to the Kil’din Island and northern Norway. Within the belt there are known stromatolitic formations of all Riphean erathems: the Lower and Middle Riphean stromatolitic buildups are confined to the eastern segment of its southern part only, while the Upper Riphean occur everywhere. Their distribution conformable to large structural elements of the plaform margin being replaced by carbonate-terrigenous rocks almost lacking stromatolites westward and southwestward in the Kama-Belaya aulacogen system and by substantially siliciclastic succession eastward and northeastward. The distribution area of Upper Riphean stromatolitic formations includes the Karatavian stratotype region, where 12 stromatolite beds ranging in age from ≥900 to 620 Ma are established. Many of the beds are traceable along the strike far beyond the stratotype region. Representing relatively small reference units, the beds facilitate reconstruction of distribution dynamics of the Upper Riphean stromatolites. Distribution area of the latter was always parallel to marginal structures of the platform, though being of changeable size, particularly of length. Originated in the stratotype region eastern part, stromatolites first advanced into northeastern areas never crossing boundaries of the Upper Riphean distribution area during the Early Karatavian. In the initial Late Karatavian, they occupied a longest distribution area that was sharply reduced at the end of that period. According to distribution peculiarities in space and with time, the Upper Riphean stromatolitic formations accumulated likely in peripheral areas of an open sea or oceanic basin adjacent to the East European platform, rather than in closed epiplatform basins.

Consolidated morphology

Grayscale dilation and erosion are basic transformations of mathematical morphology. Used together or with other transformations, they are very useful tools for image analysis. However, they can be very time consuming, especially with 3D images, and with large structuring elements. Several algorithms have been created to decrease the computation time, some of them with some limitations of shape of structuring element. We have implemented several algorithms, studied their performance in different conditions, and shown that all of them are more efficients than the others in certain conditions. We finally introduce a new structuring element class and a some meta filter designed to select the best algorithm depending on the image and the structuring element, and to smoothely integrate the different algorithms available in the toolkit.

Mycobacterium tuberculosis Protein Tyrosine Phosphatase PtpB Structure Reveals a Diverged Fold and a Buried Active Site

Intracellular pathogenic bacteria manipulate host signal transduction pathways to facilitate infection. Mycobacterium tuberculosis protein tyrosine phosphatases (PTPs) PtpA and PtpB are thought to be secreted into host cells and interfere with unidentified signals. To illuminate the mechanisms of regulation and substrate recognition, we determined the 1.7 A resolution crystal structure of PtpB in complex with the product phosphate. The protein adopts a simplified PTP fold, which combines features of the conventional PTPs and dual-specificity phosphatases. PtpB shows two unusual elaborations--a disordered, acidic loop and a flexible, two-helix lid that covers the active site--that are specific to mycobacterial orthologs. Biochemical studies suggest that substrate mimicry in the lid may protect the phosphatase from oxidative inactivation. The insertion and deletion of large structural elements in PtpB suggest that, outside the active site module, the PTP family is under unusual selective pressure that promotes changes in overall structure.

Morphological Erosions and Openings: Fast Algorithms Based on Anchors

Several efficient algorithms for computing erosions and openings have been proposed recently. They improve on van Herk's algorithm in terms of number of comparisons for large structuring elements. In this paper we introduce a theoretical framework of anchors that aims at a better understanding of the process involved in the computation of erosions and openings. It is shown that the knowledge of opening anchors of a signal f is sufficient to perform both the erosion and the opening of f. Then we propose an algorithm for one-dimensional erosions and openings which exploits opening anchors. This algorithm improves on the fastest algorithms available in literature by approximately 30% in terms of computation speed, for a range of structuring element sizes and image contents.

Statistical characteristics of large scale structure

We generalize and extend the statistical description of formation and evolution of Large Scale matter distribution in the Universe proposed in our previous papers. We investigate the impact of transverse motions – expansion and/or compression – on properties of the Large Scale Structure elements – walls, pancakes, filaments and clouds – and, generalizing the Press-Schechter formalism, derive their mass functions. Using the Zel'dovich theory of gravitational instability we show that these mass functions are approximately the same and the mass of each type of elements is found to be concentrated near the corresponding mean mass. At high redshifts, both the mass function and the mean mass of formed elements depend upon the small scale part of the initial power spectrum and, in particular, upon the mass of dominant fraction of dark matter (DM) particles. Using these results we obtain independent estimates of probable redshifts of the reionization and reheating periods of the Universe. We show that the transverse motions do not significantly change the redshift evolution of the observed mass function and the mean linear number density of low mass pancakes related to absorption lines in the spectra of the farthest quasars. Application of this approach to the observed Lyman–α forest allows one to directly estimate the shape of initial power spectrum on small scales.

Performance comparison of above ceiling and through ceiling sound masking systems

Sound masking systems are an important tool for providing speech privacy in offices and similar spaces. These systems typically use an array of loudspeakers radiating masking sound above an acoustical tile ceiling. The ceiling acts to diffuse the sound laterally in order to minimize localization on loudspeakers by the listeners below. The diffusion also helps keep the speech-to-noise ratio relatively uniform spatially, which may help minimize variations in privacy conditions. Unfortunately, the ceiling material, the plenum, and the space below are rarely homogeneous acoustically. There are usually openings in the ceiling for HVAC return air and lighting fixture ventilation, and different parts of the ceiling often use a variety of materials and elevations for aesthetic reasons. Large ducts and structural elements may compartmentalize the plenum. These variations pose substantial acoustical challenges for the designer and additional costs for the owner, not all of which can be satisfactorily resolved. Recognizing these issues, several manufacturers have recently introduced masking systems that might be characterized as direct field systems. These systems use masking loudspeakers that radiate directly into the occupied space rather than into a plenum. This paper contrasts the typical performance and other characteristics of the two basic types of systems.

Simplified Crash Models Using Plastic Hinges and the Large Curvature Description

This paper presents a simplified modeling for the crash behavior ofbeamlike structures made of rectangular or square sections tubes. Themain deformation studied is bending but the methodologies can beextended to torsion. At the beginning of the calculation, the structureis modeled as a multibody system with joints such as fixed or pinnedjoints. The bodies are meshed with large structural elements. As thesystem evolves, plastic hinges appear as new joints. For an internalhinge appearance, an adaptive procedure is applied to split theconcerned element into two. the paper ends with the example of a frameimpacted by a lumped mass. The results of the simulation are compared toa finite element resolution of the problem with ABAQUS/Explicit andother results from the literature.

Cosmological implications of heavy dark matter particles

We apply a statistical approach based on the modified Zel'dovich approximation to study distribution of dark matter and its concentration within large scale structure elements. Using this approach, we can investigate the expected dependence of structure characteristics upon the mass of dark matter particles and/or the shape of small scale power spectrum of initial density perturbations. We show that the characteristics obtained with truncated power spectra used in numerical simulations could differ from those expected to arise from the generic ones.

Compliance Acceptance of Concrete Drying Shrinkage

In Australia, strength, and in particular compressive strength, has been used in AS 3600 and AS 1379 as a benchmark for structural performance, for durability and as a contractual basis for concrete supply. With tightening financial constraints and the ensuing need for increased construction efficiencies, there is a bigger emphasis on the provision of concrete quality. Contractually, quality provision is handled by measuring parameters such as compressive strength, flexural strength, chloride ion penetration by charge transfer (ASTM C1202-91), and concrete drying shrinkage. The correct assessment of such results, together with good concreting practices, will greatly increase the certainty of achieving desired quality in terms of design intent.Concrete drying shrinkage is recognised as important in the design process for maintaining serviceability requirements particularly on large horizontal structural elements, a common example being the limitation of cracking in large slabs. The compliance basis for compressive strength is well established in AS 3600 and AS 1379. Regarding concrete drying shrinkage, however, it is common to find in many design specifications average and absolute maximum values specified at 56 days. This can create immense constructional and contractual problems when individual samples fail to comply with the specified shrinkage limit.

Structure of neurolysin reveals a deep channel that limits substrate access.

The zinc metallopeptidase neurolysin is shown by x-ray crystallography to have large structural elements erected over the active site region that allow substrate access only through a deep narrow channel. This architecture accounts for specialization of this neuropeptidase to small bioactive peptide substrates without bulky secondary and tertiary structures. In addition, modeling studies indicate that the length of a substrate N-terminal to the site of hydrolysis is restricted to approximately 10 residues by the limited size of the active site cavity. Some structural elements of neurolysin, including a five-stranded beta-sheet and the two active site helices, are conserved with other metallopeptidases. The connecting loop regions of these elements, however, are much extended in neurolysin, and they, together with other open coil elements, line the active site cavity. These potentially flexible elements may account for the ability of the enzyme to cleave a variety of sequences.

Structuring element decomposition for efficient implementation of morphological filters

In order to implement morphological filters on image processing systems. The size of the structuring element must be small due to the architectural constraints of the systems. The decomposition of the structuring element is required for filters with large structuring elements. An algorithm for the decomposition of an arbitrary 4-connected binary structuring element is developed which enables sub-optimal implementation of binary morphological filters on a 3/spl times/3 pipeline machine. The given structuring element is first decomposed into the union of elements using a sequential search procedure, then each element is further decomposed optimally into 3/spl times/3 elements, resulting in final sub-optimal 3/spl times/3 hybrid decomposition. The proposed algorithm is applied to some structuring elements and results close to the optimum are obtained.

A Framework for Conceptualizing Human Effects on Landscapes and Its Relevance to Management and Research Models

Abstract: The concept of habitat fragmentation is limited in its ability to describe the range of possible landscape configurations created by a variety of disturbances. This limitation is especially problematic in landscapes where human use of the habitat matrix occurs at multiple levels and where habitat modification may be a more important consideration than a simple binary classification of habitat versus nonhabitat. We propose a synthesizing scheme that places intact, variegated, fragmented, and relictual landscape states on a continuum, depending on the degree of habitat destruction. At a second level, the scheme considers the patterns of habitat modification that are imposed on remaining habitats. Management for conservation involves halting and sometimes reversing the trends of habitat destruction and modification. Conservation strategies will differ according to the state of alteration of the landscape, but all strategies include some consideration of the degree of modification of the matrix in determining habitat viability. It is convenient for biologists to assess landscape alteration state in terms of the persistence of large structural elements such as trees. Because animal species use habitats differently, however, they also experience the landscape differently. A landscape considered structurally fragmented by humans may be functionally variegated to other species. Therefore, it is necessary to consider the extent to which the entire landscape, including the matrix, is accessible and utilized by organisms with different spatial scales of resource use.