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[en] EF-hand proteins can be activated by the binding of various heavy metals other than calcium, and such complexes can disturb the calcium-signaling pathway and cause toxicity and disease causing state. So far, no comprehensive study has been done to understand different heavy metals binding to calcium signaling proteins. Energetically, Ca2+ is preferred in three sites, while in one site Ba2+ has better binding energy. The Sr2+-coordination in the EF hand motifs is similar to that of the native Ca2+ bound structure, except for the lack of water coordination. Sr2+-coordination seems to be a pre-formed in nature since all seven coordinating atoms are from the protein itself, which also correlates with entropy contributions in Sr2+ binding. These findings improve our understanding of metal association with calcium binding proteins and of metal induced conformational changes.
[en] This research use of lime filler Sukaraja expected add durability layers of concrete pavement is asphalt damage caused by the weather and load traffic. This study attempts to know how much value characteristic Marshall on a mixture of concrete asphalt using lime filler. This research uses experimental methods that is with a pilot to get results, thus will look filler utilization lime on construction concrete asphalt variation in filler levels 2 %, 3 %, 4 %.The results showed that the use of lime filler will affect characteristic a mixture of concrete asphalt. The more filler chalk used to increase the value of stability. On the cretaceous filler 2 % value of stability is 1067,04 kg. When lime filler levels added to the levels of filler 4 %, the value of stability increased to 1213,92 kg. The flexibility increased the number of filler as levels lime 2 % to 4 % suggests that are conducted more stiff mix. (paper)
[en] In this study, the effect of prestressed strand diameters, providing the beam-to-column connections, was investigated from both experimental and analytical aspects. In the experimental studies, the strength, stiffness and energy dissipation capacities of the precast specimens comprising two prestressed strand samples of 12.70 mm and 15.24 mm diameters, were compared with the reference specimen. The precast specimen with strands of 15.24 mm reached 96% of the maximum strength of the reference specimen; the amount of energy dissipated by this specimen by the end of the experiment reached 48% of the amount of energy dissipated by the reference sample; and the stiffness of the same specimen at a drift of 1.5% reached 77% of the stiffness of the reference specimen at this drift. Parallel results were obtained during the analytical studies from the aspects of strength and behavior, but the initial stiffness of the analytical models was lower than that of the test specimens.
[en] The mechanical design and analysis of the LCLS II 2 K cold box are presented. Its feature and functionality are discussed. ASME B31.3 was used to design its internal piping, and compliance of the piping code was ensured through flexibility analysis. The 2 K cold box was analyzed using ANSYS 17.2; the requirements of the applicable codes—ASME Section VIII Division 2 and ASCE 7-10—were satisfied. Seismic load was explicitly considered in both analyses. (paper)
[en] The authors have addressed the change of main cable tensioning force as the means of suspension bridge stiffness control. An ANSYS 3D model of a suspension bridge was developed. The dead load stress-strain behaviour and dynamic response of the model were analyzed. The study has shown that 7.5 fold increase of the main cable pre-tensioning force reduced the displacement in the middle of the central span of the stiffening girder by 40%, while in the middle of the end span, a 9% increase in displacement was observed; and displacement of the tower apex reduced by 28%. Modal analysis has shown that the main cable pre-tensioning force in the 3D model had effect neither on the natural vibration frequency spectrum of the structure, nor on the distribution of the principal modes in the spectrum. With a 7.5 fold increase of the main cable pre-tensioning force, the values of natural fundamental frequencies have changed within 2% range. The results obtained by the authors allow for the conclusion that varying the pre-tensioning force of the main cable has little effect on a suspension bridge dynamic response control. At the same time, pre-tensioning of the main cable allows control over the stiffness of the hybrid cross-tie system. (paper)
[en] The transverse impact characteristics of a rubber pipe expansion joint are studied. A pair of joints assembled end to end with an inserted middle mass is tested on a drop shock testing machine. Based on the test results, an equivalent fixed-fixed beam model with polynomial stiffness and damping is applied to predict the transverse impact response and identify the nonlinear impact parameters. The least square residual between the computed and test results is defined to drive the identification optimization. The response surface methodology in combination with the generalized reduced gradient method is used to search the best matching coefficients. Final results show that the equivalent bending stiffness of the tested rubber expansion joint gradually decreases with the transverse deformation and is greatly influenced by its internal working pressure
[en] Constitutive models based on a non-associated flow rule (non-AFR) have received increased attention due to their flexibility in capturing laboratory experiments. On the other hand, the recently proposed Fourier Asymmetric Yield (FAY) model enables the definition of convex yield functions with arbitrary complexity, which can be used in conjunction to an associated flow rule and nevertheless accurately match experimental data. The present contribution aims comparing AFR and non-AFR based approaches with respect to their ability in capturing measured strain fields in controlled Nakajima experiments. It is shown that a sufficiently flexible yield function is able of delivering accurate results without having to renounce to restrictions such as flow rule association or convexity. The analysis is carried out using two common deep drawing materials, namely an AA6016 and a steel grade DC05. (paper)
[en] The frequency range over which a mount can isolate a mass from a vibrating base (or vice versa) is often limited by the mount stiffness required to support the weight of the mass. This compromise can be made more favourable by employing non-linear mounts with a softening spring characteristic such that small excursions about the static equilibrium position result in small dynamic spring forces and a correspondingly low natural frequency. This paper concerns the force-displacement characteristic of a so-called quasi-zero-stiffness (QZS) mechanism which is characterised by an appreciable static stiffness but very small (theoretically zero) dynamic stiffness. The mechanism studied comprises a vertical spring acting in parallel with two further springs which, when inclined at an appropriate angle to the vertical, produce a cancelling negative stiffness effect. Analysis of the system shows that a QZS characteristic can be obtained if the systems parameters (angle of inclination and ratio of spring stiffness) are opportunely chosen. By introducing the additional criterion that the displacement of the system be largest without exceeding a desired (low) value of stiffness an optimal set of parameter values is derived. Under sufficiently large displacements the stiffness of the QZS mechanism can eventually exceed that of the simple mass-spring system and criteria for this detrimental scenario to arise are presented
[en] The space lattice beam is a complex statically indeterminate rod structure which, composed with several beams, is an important process for calculating the internal force and lateral stiffness in the design analysis. First, taking the single-chip truss structure with variable section as research object, each member’s force, lateral displacements and flexibility coefficients of the tapered truss with different arrangement in the form of webs are given. Finally, based on the flexibility coefficient of monolithic truss structure, considering it comprehensively with the effects of lateral stiffness caused by the chords and webs, the lateral displacement expressions are deduced for rectangular space truss structure. Result of analysis of examples show that the application of the method mentioned in this paper to calculate the lateral displacement of space lattice beam with variable section is correct and effective which can be used for practical engineering. (paper)
[en] This paper presents the results of a dynamic analysis on unstiffened and stiffened corrugated panels subjected to hydrocarbon explosion. A parametric study is also conducted on simplified models of the stiffened corrugated panels considering the effect of stiffeners on the compressive flange under different loading levels. The 1/2 symmetry of corrugated panels is modeled. This numerical study is performed using NX Nastran version 7.5. The unstiffened panel produces localized buckling at the center of corrugation and large permanent deformation by increasing the peak pressure. The stiffened panels suppress the structural response, and the vee stiffeners are structurally more effective than the round ones