Fundamental Structural Elements Research Articles

Theoretical and Applied Insights on Pistons Buckling According to DNV Regulation

Pistons are fundamental structural elements in any engineering practices such as mechanical, civil, aerospace, and offshore engineering. Their strength strongly depends on buckling load, and such information is a major requirement in the design process. Euler's linear buckling equation is the most common and most used model in design. It is well suited for linear elastic members without geometrical imperfections and nonlinear behavior. Several analytical and experimental investigations of typical hydraulic cylinders have been carried out through the years but most of the available standards still use a linear approach with many simplifications. Pistons are slender beams with not-uniform cross section, which need a stronger effort than the classical Euler's approach. The present paper aims to discuss limitations of current DNV standards for piston design in offshore technologies when compared to classical numerical approaches and reference results provided by the existing literature.

Effect of fatigue crack propagation on natural frequencies of system in AISI 4140 Steel

In this study, we investigated the effect of fatigue crack propagation of the beams which have a vital importance in engineering applications, on the natural frequency of the system. Beams which have a wide range of applications, are used as fundamental structural elements in engineering structures. Therefore, early detection of any damages in these structures is of vital importance for the prevention of possible destructive damages. One of the widely used methods of early detection of damages is the vibration analysis of the structure. Hence, it is of vital importance to detect and monitor any changes in the natural frequencies of the structure. From this standpoint, in this study we experimentally investigated the effect of fatigue crack propagation on beams produced from 4140 steel, of the natural frequency of the beam. A crack was opened on the 8

Progressive structural capacity loss assessment-A framework for modern reinforced concrete buildings.

By the virtue of burgeoning terrorism, the exponential growth of advanced weaponry, and allied aids for explosions, it is quite evident that infrastructural facilities in the world have increasingly become more susceptible to sabotaging activities. The ever enhancing employment of reinforced concrete (RC) in the construction industry around the globe, the progressive collapse mechanisms, and respective mitigation strategies in the context of terrorism have garnered quite an attraction by the structural engineering community. The proficiency to envisage the complete collapse under the chain reaction of structural failures, partial collapse of key structural members, or the strength degradation of fundamental structural elements under the blast or impact loading can deliver significant information to cope with partial or complete structural failure. It is quite convenient to say that during the service life, a structure may experience extreme loading conditions. The current study has proposed a new methodology to cover the effect of uncertainty involved in loading on key structural elements of new and complex structures by emphasizing a very realistic structural capacity loss mechanism that allows the incremental reduction in the structural capacities of pivotal structural elements against any sort of impact loading instead of their complete annihilation. To demonstrate the application of the proposed methodology, a 13-story complex structure was selected that was comprised of a diverse structural configuration. The outcomes and results ensured the structural integrity against the applied loadings, as well as the effectiveness of the proposed methodology.

IMPROVING THE QUALITY AND COMPETITIVENESS OF GRAIN

in modern conditions for solving numerous issues of improving the quality of grain, it is important to identify three fundamental structural elements of the development of the grain-producing subcomplex of the country: the selection and seed production of grain crops, pro-duction and processing of grain, which are united by a common technological scheme of the im-plementation of quality characteristics of various grades and hybrids of grain crops in view of tar-geted use of their products.

A structural look at α-synuclein oligomers

Neurodegeneration Fibrillar aggregates of the protein α-synuclein (αS) are the major constituents of Lewy bodies in Parkinson's disease. However, small oligomers that accumulate during the process of fibril formation are thought to cause the neuronal toxicity associated with the onset and progression of Parkinson's disease. Little is known about the detailed structural properties of αS oligomers and the molecular mechanisms that lead to their toxicity. Fusco et al. report the structural characterization of two forms of αS oligomers, which elucidates the fundamental structural elements giving rise to neuronal toxicity. Science , this issue p. [1440][1] [1]: /lookup/doi/10.1126/science.aan6160

Problems with the Word Made Flesh: The Great Tradition of the Scientific Revolution in Europe

Abstract The Great Tradition of writing about what came to be called The Scientific Revolution developed in the mid-twentieth century and helped to shape what came to be termed “early modern” Europe. At least two fundamental structural elements of the framework were that a small group of independent minds had been set free to grasp new truths, and that rivalries among many groups in Europe never allowed “European civilization” to achieve homeostasis, thus continuing to encourage innovation in conditions of freedom. It is worth noting, however, that the first of these structural elements had religious overtones that were important in the early stages of the Cold War, and that the second placed innovation within a tradition of great texts rather than material culture and practice. Both changed the earlier conversation of the 1930s, which had been about political economies, connecting the new history of science to a history that offered to explain European superiority on the basis of the search for truth. Recent developments in global history, which are rooted in economic histories, challenge such a framing. The brand-name of The Scientific Revolution is common and will remain a useful short-hand, but its meaning requires major revision and should not be limited to the history of Europe.

Prediction of Changes in Modal Properties of the Euler–Bernoulli Beam Structures Due to the Modification of Its Spatial Properties

The beams can be considered as fundamental structural elements applied in many technical structures and equipment. In the operating regimes, these beam structures are very often loaded by the time-dependent forces which cause their undesirable dynamical behavior and the whole system is getting into critical resonant state. It is clear that the reduction of the level of unwanted vibrations or prevention of their occurrence should be one of the important objectives in the design of machine equipment and structures. To achieve these aims, the knowledge of modal properties of beam structures in relation to their internal structure is necessary. The insertion of reinforcing core into a beam body is one of the possible techniques to achieve the required changes in modal properties (mode shapes, natural frequencies) of the beam structure. The dependency of the modal properties of structurally modified beam structure on the geometric parameters and material properties of the inserted reinforcing core is studied in this paper.

Structural basis of ligand interaction with atypical chemokine receptor 3

Chemokines drive cell migration through their interactions with seven-transmembrane (7TM) chemokine receptors on cell surfaces. The atypical chemokine receptor 3 (ACKR3) binds chemokines CXCL11 and CXCL12 and signals exclusively through β-arrestin-mediated pathways, without activating canonical G-protein signalling. This receptor is upregulated in numerous cancers making it a potential drug target. Here we collected over 100 distinct structural probes from radiolytic footprinting, disulfide trapping, and mutagenesis to map the structures of ACKR3:CXCL12 and ACKR3:small-molecule complexes, including dynamic regions that proved unresolvable by X-ray crystallography in homologous receptors. The data are integrated with molecular modelling to produce complete and cohesive experimentally driven models that confirm and expand on the existing knowledge of the architecture of receptor:chemokine and receptor:small-molecule complexes. Additionally, we detected and characterized ligand-induced conformational changes in the transmembrane and intracellular regions of ACKR3 that elucidate fundamental structural elements of agonism in this atypical receptor.

Rates of erosion and landscape change along the Blue Ridge escarpment, southern Appalachian Mountains, estimated from in situ cosmogenic 10Be

AbstractThe Blue Ridge escarpment, located within the southern Appalachian Mountains of Virginia and North Carolina, forms a distinct, steep boundary between the lower‐elevation Piedmont and higher‐elevation Blue Ridge physiographic provinces. To understand better the rate at which this landform and the adjacent landscape are changing, we measured cosmogenic beryllium‐10 (10Be) in quartz separated from sediment samples (n = 50) collected in 32 streams and from three exposed bedrock outcrops along four transects normal to the escarpment, allowing us to calculate erosion rates integrated over 104–105 years. These basin‐averaged erosion rates (5.4–49 m Myr−1) are consistent with those measured elsewhere in the southern Appalachain Mountains and show a positive relationship between erosion rate and average basin slope. Erosion rates show no relationship with basin size or relative position of the Brevard fault zone, a fundamental structural element of the region. The cosmogenic isotopic data, when considered along with the distribution of average basin slopes in each physiographic province, suggest that the escarpment is eroding on average more rapidly than the Blue Ridge uplands, which are eroding more rapidly than the Piedmont lowlands. This difference in erosion rates by geomorphic setting suggests that the elevation difference between the uplands and lowlands adjacent to the escarpment is being reduced but at extremely slow rates. Copyright © 2016 John Wiley & Sons, Ltd.

Energy scaling and reduction in controlling complex networks.

Recent works revealed that the energy required to control a complex network depends on the number of driving signals and the energy distribution follows an algebraic scaling law. If one implements control using a small number of drivers, e.g. as determined by the structural controllability theory, there is a high probability that the energy will diverge. We develop a physical theory to explain the scaling behaviour through identification of the fundamental structural elements, the longest control chains (LCCs), that dominate the control energy. Based on the LCCs, we articulate a strategy to drastically reduce the control energy (e.g. in a large number of real-world networks). Owing to their structural nature, the LCCs may shed light on energy issues associated with control of nonlinear dynamical networks.

Numeric reconstruction of 2D cellular actomyosin network from substrate displacement

Introduction: One of the fundamental structural elements of the cell is the cytoskeleton. Along with myosin, actin microfilaments are responsible for cellular contractions, and their organization may be related to pathological changes in myocardial tissue. Due to the complexity of factors involved, numerical modeling of the cytoskeleton has the potential to contribute to a better understanding of mechanical cues in cellular activities. In this work, a systematic method was developed for the reconstruction of an actomyosin topology based on the displacement exerted by the cell on a flexible substrate. It is an inverse problem which could be considered a phenomenological approach to traction force microscopy (TFM). Methods An actomyosin distribution was found with a topology optimization method (TOM), varying the material density and angle of contraction of each element of the actomyosin domain. The routine was implemented with a linear material model for the bidimensional actomyosin elements and tridimensional substrate. The topology generated minimizes the nodal displacement squared differences between the generated topology and experimental displacement fields obtained by TFM. The structure resulting from TOM was compared to the actin structures observed experimentally with a GFP-attached actin marker. Results The optimized topology reproduced the main features of the experimental actin and its squared displacement differences were 11.24 µm2, 27.5% of the sum of experimental squared nodal displacements (40.87 µm2). Conclusion This approach extends the literature with a model for the actomyosin structure capable of distributing anisotropic material freely, allowing heterogeneous contraction over the cell extension.

Insight into a molecular interaction force supporting peptide backbones and its implication to protein loops and folding

Although not being classified as the most fundamental protein structural elements like α-helices and β-strands, the loop segment may play considerable roles for protein stability, flexibility, and dynamic activity. Meanwhile, the protein loop is also quite elusive; i.e. its interactions with the other parts of protein as well as its own shape-maintaining forces have still remained as a puzzle or at least not quite clear yet. Here, we report a molecular force, the so-called polar hydrogen–π interaction (Hp–π), which may play an important role in supporting the backbones of protein loops. By conducting the potential energy surface scanning calculations on the quasi π-plane of peptide bond unit, we have observed the following intriguing phenomena: (1) when the polar hydrogen atom of a peptide unit is perpendicularly pointing to the π-plane of other peptide bond units, a remarkable Hp–π interaction occurs; (2) the interaction is distance and orientation dependent, acting in a broad space, and belonging to the ‘point-to-plane’ one. The molecular force reported here may provide useful interaction concepts and insights into better understanding the loop’s unique stability and flexibility feature, as well as the driving force of the protein global folding.

A Study of the Semiotic Understanding of Land Art

Semiotics is the science of signs. It is known as an approach to expose the fundamental structural elements of the meaning of an object or a term. It comprises of the study of signs, designation, indication, analogy, likeness, symbolism, signification, metaphor, and communication. Semiotic and land art are closely associated with each other. Land art consists of sculptures, carvings, and performances located at specific natural surroundings to deliver messages of love and concern for the environment, even though they are ephemeral or located in inaccessible places they are transmitted by the semioticians. Like all works of art, each piece could be classified as abstract or realistic and would be created using signs and symbols of the artist’s semiotic system to code the messages and feelings. The aim of this article is to examine the semiotics of land art based on signs and symbols of landscape through documentary analysis. The findings of the study revealed that semiotics is a powerful tool to reflect feelings and sentiments regarding different landscape. Some implications were also furnished.

The Transformation of Chinese Enterprise Income Tax: Internationalization and Chinese Innovations

This article reviews the major elements of the enterprise income tax (EIT) system in China and examines the dynamic relationship between international norms and the local Chinese context. After some introductory remarks, the article discusses the fundamental principles, concepts and structural elements of the EIT system and examines its main transformative aspects in terms of form, process and substantive provisions. The article also considers the extent to which international tax norms, China's policy concerns and traditional issues play a role in the new system. The article concludes with some observations on international tax norms.

William Storm Irony and the Modern TheatreIrony and the Modern Theatre. William Storm. New York: Cambridge University Press, 2011. Pp. ix+256.

<i>William Storm</i> Irony and the Modern Theatre<i>Irony and the Modern Theatre</i>. William Storm. New York: Cambridge University Press, 2011. Pp. ix+256.

“On the System of Stravinsky’s Harmony” by Yuri Kholopov

Yuri Kholopov is generally regarded as the foremost Russian music theorist in the latter half of the twentieth century. Though he published articles in a wide array of topics, he was happiest when discussing twentieth-century concepts; it was to this end that he devoted a large part of his life’s work. The essay by Kholopov translated in the present article is from 1997, six years before he died. There are several significant points that he makes with respect to Stravinsky’s music. First, Kholopov links a quotation from Stravinsky on harmony to Sergei Taneev’sInvertible Counterpoint in the Strict Style, thus suggesting that by borrowing ideas from Taneev, the Petersburg-based Stravinsky was influenced by the Moscow-based Taneev. This speaks to a possible Russian influence on Stravinsky aside from Rimsky-Korsakov, whose influence on Stravinsky is not in doubt. Second, Kholopov posits a new fundamental “neotonality” in Stravinsky’s music, which exhibits a “central element” (CE) to which all other tones gravitate. Third, Kholopov’s work situates octatonicism into a broader framework of Stravinsky’s compositional practices. Ultimately, it is but one aspect of this music and is not emphasized as a fundamental structural element in Stravinsky’s music, as it is in writings by Arthur Berger, Pieter van den Toorn, and Richard Taruskin, for example. Fourth, in the section on polarity, Kholopov posits that when Stravinsky uses this term in relation to his music, he may have meant to say “stability,” which was a term from the writings of Boleslav Yavorsky that most Russian musicians knew in the early twentieth century. This reinterpretation of polarity sheds new light on this most important concept in Stravinsky studies. Lastly, there is the idea that Stravinsky was, in fact, a serial composer for his entire life. Of course, Stravinsky famously claimed so himself late in life; Kholopov solidifies this claim, traces the evolution of Stravinsky’s serial works, and finds an intriguing four-note series inFirebird.

제작성을 개선한 하이브리드 FRP-콘크리트 합성말뚝의 압축거동

말뚝은 상부구조물에 작용하는 하중을 지반에 전달하는 구조요소로서, 일반적으로 말뚝기초는 지중 또는 수면 아래 지중에 건설된다. 이러한 환경은 부식 또는 염해를 유발하여 말뚝에 손상을 야기한다. 지중 및 수중 구조요소인 말뚝이 손상될 경우, 손상에 따른 내구성을 평가하기 어려우며 추가적인 보수보강 및 유지관리 또한 어렵다. 이 연구에서는 말뚝기초의 내구성과 제작성을 개선하기 위하여 하이브리드 FRP-Concrete 합성말뚝(HCFFT)을 제안하였다. 제안된 HCFFT에 대한 유한요소해석과 실험을 실시하여, 이를 바탕으로 HCFFT의 최대하중 추정식을 제안하였다. 또한, 제안된 HCFFT의 제작과정에서의 문제점을 개선한 새로운 형태의 HCFFT의 형태를 제안하고, 유한요소해석을 실시하여 동일한 직경의 PHC 말뚝과 강관말뚝의 축방향 압축력을 HCFFT 말뚝의 축방향 압축력과 비교하여 HCFFT 말뚝의 장점을 확인하였다. As a fundamental structural element of construction, a pile is constructed to transfer loads from superstructure to foundation. In general, since the pile foundation is constructed in the ground or ground under water, it is difficult to protect from the damages due to moisture and/or salt which create corrosive environment and it is even more difficult to estimate its durability. In this study, in order to enhance the durability and constructibility of the pile foundation, FRP-concrete hybrid composite pile (HCFFT) is suggested. Moreover, equation for the prediction of load carrying capacity of HCFFT circular members under compression is suggested and discussed based on the results of analytical and experimental investigations. In addition, we also conducted the finite element simulation for the structural behavior of new HCFFT composite pile and the result is compared with those of experimental and analytical studies. In addition, the axial loading capacity of new HCFFT composite pile is compared with those of existing PHC pile and hollow circular steel pipe pile, and it was found that the new HCFFT composite pile has advantages over conventional PHC and steel pipe piles.

Differences in the Structural Stability and Cooperativity between Monomeric Variants of Natural and de Novo Cro Proteins Revealed by High-Pressure Fourier Transform Infrared Spectroscopy

It is widely accepted that pressure affects the structure and dynamics of proteins; however, the underlying mechanism remains unresolved. Our previous studies have investigated the effects of pressure on fundamental secondary structural elements using model peptides, because these peptides represent a basis for understanding the effects of pressure on more complex structures. This study targeted monomeric variants of naturally occurring bacteriophage λ Cro (natural Cro) and de novo designed λ Cro (SN4m), which are α + β proteins. The sequence of SN4m is 75% different from that of natural Cro, but the structures are almost identical. Consequently, a comparison of the folding properties of these proteins is of interest. Pressure- and temperature-variable Fourier transform infrared spectroscopic analyses revealed that the α-helices and β-sheets of natural Cro are cooperatively and reversibly unfolded by pressure and temperature, whereas those of SN4m are not cooperatively unfolded by pressure; i.e., the α-helices of SN4m unfold at significantly higher pressures than the β-sheets and irreversibly unfold with increases in temperature. The higher unfolding pressure for the α-helices of SN4m indicates the presence of an intermediate structure of SN4m that does not retain β-sheet structure but does preserve the α-helices. These results demonstrate that the α-helices of natural Cro are stabilized by global tertiary contacts among the α-helices and the β-sheets, whereas the α-helices of SN4m are stabilized by local tertiary contacts between the α-helices.

Comment on “Material Nature versus Structural Nurture: The Embodied Carbon of Fundamental Structural Elements”

MATERIAL NATURE VERSUS STRUCTURAL NURTURE: THE EMBODIED CARBON OF FUNDAMENTAL STRUCTURAL ELEMENTS Roger Sathre, Ambrose Dodoo, Leif Gustavsson, Bruce Lippke, Gregg Marland, Eric Masanet, Birger Solberg, and Frank Werner Environmental Energy Technologies Division Lawrence Berkeley National Laboratory Berkeley, CA 94720 May 2012 Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Response to the Comment on “Material Nature versus Structural Nurture: The Embodied Carbon of Fundamental Structural Elements”

Response to the Comment on “Material Nature versus Structural Nurture: The Embodied Carbon of Fundamental Structural Elements”