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1
Huang, Tao, and Yi Liu. "The Analysis of Structure Deformation Using DDA with Third Order Displacement Function." Advanced Materials Research 446-449 (January 2012): 906–16. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.906.
Testo completoAbstract (sommario):
Third order displacement function is introduced into DDA (DDA3O), which can easy to analysis the nonlinear distribution of deformation, stress and strain within a single block. In this paper, additional nodes were inserted on the boundary. So, when large deformation is involved, even the original straightly boundary of block will deform to one formed by curved edges, the simplex integration along the curved edge can increase accuracy and simulation of contact between blocks can be more reasonable. On the other hand，the problem of transferring the initial stress from previous step to next step is difficulty and unresolved problem, because of the strain matrix of high order displacement function involving the unknown variables x, y. A new method presented herein is inherent previous the displacement of block to next step, which is proved right and efficient. At last, some example was calculated to demonstrate the excellent accuracy and efficiency of DDA3O.
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Dong, Chang Zhou, and Chen Qu. "Analysis of Steel-Concrete Composite Structure Element." Applied Mechanics and Materials 94-96 (September 2011): 402–5. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.402.
Testo completoAbstract (sommario):
The structure of eccentric degenerated 3-D shell element of thin-wall steel tube concrete composite structure and the connection with 3-D block isoparametric element has been discussed using finite element method. Without considering the intensity limit of delamination damage of the two materials, an integrated stiffness matrix is formed with the combination of stiffness matrix of steel-wall shell element and that of concrete spatial block element. In order to make the superposition rule may be used at the joint of 8-node curved shell element and 20-node block element, an eccentric 8-node shell element is constructed.
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Lin, Yu-Liang, Ming-Hsiang Cheng, Chun-Wei Chang, Chien-Wei Chu, Chih-Ting Liu, and Jiun-Tai Chen. "Curved block copolymer nanodiscs: structure transformations in cylindrical nanopores using the nonsolvent-assisted template wetting method." Soft Matter 15, no. 41 (2019): 8201–9. http://dx.doi.org/10.1039/c9sm01633c.
Testo completo
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Saini, Paramdeep, Apoorv Pandhi, and A. K. Darpe. "An Experimental Study on the Use of Active Constrained Layer Damping for Thin Curved Smart Shell Structures." Advances in Science and Technology 56 (September 2008): 309–14. http://dx.doi.org/10.4028/www.scientific.net/ast.56.309.
Testo completoAbstract (sommario):
Thin Open Curved Shell Structures constitute the major building block of many critical structures such as Aircraft Cabins, Ship Hulls and bodies of rockets and missiles. In the present work, an open thin curved shell made of Aluminium material has been chosen to investigate the potential of ACLD effectiveness with MFC Actuator. The shell ACLD system has been modelled using system identification method and converted into state space form for designing the control law of the LQR controller. Finite Element Analysis of the bare structure has been performed in ANSYS. Using modal solution results, the best possible location for the placement of patches has been found out for combined vibration control of first three modes using Modal Strain Energy (MSE) approach. The FEA Modal Solution results have been correlated with the experimental modal analysis results obtained with the help of ICATS (Imperial College’s Modal Analysis and Testing Software). Significant vibration attenuation resulted for partially covered PCLD and ACLD treatments on open curved shell. Thus, ACLD provides a practical means for controlling the vibration of complex structures such as an open curved shell with currently available piezoelectric (MFC) actuators without the need for excessively large actuation voltages.
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Yamashita, Minoru, and Toshio Hattori. "Onset of Progressive Buckling by Inertia Force in Axial Impact of Straight and S-Curved Square Tubes." Advanced Materials Research 445 (January 2012): 847–52. http://dx.doi.org/10.4028/www.scientific.net/amr.445.847.
Testo completoAbstract (sommario):
For the improvement of the deformation characteristic and the energy absorption efficiency of the tubular structure at impact event, a method generating the first buckling lobe using the inertia force was investigated. The solid block was attached to the wall so that its inertia force causes the partial plastic deformation that plays a role of the trigger of progressive buckling at the beginning of impact. Drop-weight impact experiment revealed that the onset of progressive buckling was achieved at the desired portion by the method. To increase the variety of tube shapes, numerical examination was conducted with the dynamic explicit finite element method. Long straight and S-curved tubes, which have square cross-section, were numerically modeled with shell elements. They were assumed to be impacted to the rigid wall to estimate the dynamic collapse behavior. The first buckling lobe generated by inertia force was demonstrated for the straight tube. The S-curved tube exhibited a bending collapse mode without the method. However, such mode was avoidable by applying the method. Then the energy absorption efficiency of the tube was drastically increased.
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Chan, Vincent W. S., Hugo Nova, Sherif Abbas, Colin J. L. McCartney, Anahi Perlas, and Da Quan Xu. "Ultrasound Examination and Localization of the Sciatic Nerve." Anesthesiology 104, no. 2 (2006): 309–14. http://dx.doi.org/10.1097/00000542-200602000-00017.
Testo completoAbstract (sommario):
Background Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation. Methods In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded. Results The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion. Conclusions These preliminary data show that a curved 2- to 5-MHz ultrasound probe provides good quality sciatic nerve imaging in the gluteal, infragluteal, and proximal thigh locations. Ultrasound-assisted sciatic nerve localization is potentially valuable for clinical sciatic nerve blocks.
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Polyakov, V. A. "Automation of the Algorithm for Designing a Reinforcement Scheme for a Structure Made of Composite Materials." LETI Transactions on Electrical Engineering & Computer Science 15, no. 7 (2022): 14–19. http://dx.doi.org/10.32603/2071-8985-2022-15-7-14-19.
Testo completoAbstract (sommario):
The paper considers the development and automation of an algorithm for designing a reinforcement scheme based on bending deformation. The algorithm is presented in the form of a block diagram. When searching for a reinforcement trajectory, the algorithm takes into account the specified criteria for searching and designing a scheme. On the basis of the algorithm, a program is developed that can operate with the data of the model under study, use them to construct and synthesize the reinforcement trajectory. The program code is based on a simple example – bending deformation. The stress-strain state (SSS) is analyzed, the deformation proceeds linearly and in one direction. As a result, the reinforcement paths are straight lines. For nonlinear deformation, this code provides a spline function that is used to construct curved trajectories. Automation of the algorithm for designing reinforcement trajectories in the form of a program made it possible to reduce the time of searching, processing and compiling trajectories.
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Khlebnikov, Denis V. "Standard Units in Miniatures of the Manuscript no. 20 in Russian State Library, Fund 173.I." Vestnik of Saint Petersburg University. Arts 13, no. 3 (2023): 508–34. http://dx.doi.org/10.21638/spbu15.2023.307.
Testo completoAbstract (sommario):
The proposed article is addressed to the phenomenon of typical graphic elements used in Russian late medieval visual art; the study is based on the material of miniatures of the wellknown illuminated manuscript of the Commentated Prophet Book from the collection of the Moscow Theological Academy. Previously, a detailed comparison of the drawing of paper icon samples, and later of the icons themselves of the 15th–16th centuries as well, led to the conclusion that icon painters widely use a set of the same systematically repeating graphic elements. They can always be seen in almost any icon, in different numbers and different combinations, in the most dissimilar images and regardless of who or what is depicted on the icon: the Savior, the Virgin or a prophet; regardless of whether the image in front of us is a half-length image, shoulder-length or full-length figure; regardless of the pose, gestures and type of clothing. Those elements are used constantly, although their number and set may vary significantly from case to case. In addition, their graphics vary quite freely: the proportions within the block and its dimensions change relative to other parts of the image, straight lines may be more or less curved, or part of the block may be hidden by another detail or, on the contrary, shown two or more times. Sometimes some part of the block is inverted, shifted or reduced, but the structure of the block remains the same. This observation makes it possible to significantly clarify the ideas about the principles of icon-painter work in the 15th–17th centuries: the drawing, for example, of a human figure and their robes was not copied literally from icon to icon, neither was invented completely anew each time; the image was more or less “constructed” from already existing ready-made blocks, either in the literal sense, or they filled in a ready-made general compositional scheme or a part of it, which itself can be considered as a standard block of a higher order. The miniatures of the manuscript under study serve as a clear example of the use of standard blocks in the Moscow illuminated book of the 15th century. The article for the first time compares a large number of deesis and prophetic images.
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Li, Peiyong, Zheng Tang, Yuwen Huang, Yunpeng Wang, and Chong Wang. "Distortion Control and Prevention by Fabrication Techniques in Cold Bent Steel Frame with Perforated Web." Journal of Ship Production and Design 37, no. 01 (2021): 37–44. http://dx.doi.org/10.5957/jspd.07190038.
Testo completoAbstract (sommario):
Cutouts are widely used in ships and offshore structures. Cutouts of big size are used mainly for inspection, passing pipes, and weight reduction. Some cutouts of small size may be used for various purposes, such as water hole in the web of stiffeners. The stiffeners with perforated web are the most commonly adopted structure members in the shipbuilding industry, and they are mainly fabricated by cutting and bending the frame to meet the requirements of desired design configuration. In ship production, the manufacture of the curved stiffener with holes is desirable to perforate first and then to bend the frame. This fabrication procedure is adopted for efficient production because of the layout of the production line. However, structural distortion and damage may occur during cold bending of the frames with perforated web, such as necking, wrinkling, and even crack initiation. This problem should be solved in ship production. In this study, cold bending experiments and finite element simulations were performed to analyze the deformation characteristics of curved frames with cutouts. A fabrication method is proposed to control the deformation in the cutouts during the bending process. In this method, the block cut out during the first step is filled in the hole and afterward the frame is bent. The results show that this method can control well the deformation localized around the hole during the bending process. It offers an important guidance for cold bending steel frames in ship production.
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Ren, Yingying, Uday Kusupati, Julian Panetta, et al. "Umbrella meshes." ACM Transactions on Graphics 41, no. 4 (2022): 1–15. http://dx.doi.org/10.1145/3528223.3530089.
Testo completoAbstract (sommario):
We present a computational inverse design framework for a new class of volumetric deployable structures that have compact rest states and deploy into bending-active 3D target surfaces. Umbrella meshes consist of elastic beams, rigid plates, and hinge joints that can be directly printed or assembled in a zero-energy fabrication state. During deployment, as the elastic beams of varying heights rotate from vertical to horizontal configurations, the entire structure transforms from a compact block into a target curved surface. Umbrella Meshes encode both intrinsic and extrinsic curvature of the target surface and in principle are free from the area expansion ratio bounds of past auxetic material systems. We build a reduced physics-based simulation framework to accurately and efficiently model the complex interaction between the elastically deforming components. To determine the mesh topology and optimal shape parameters for approximating a given target surface, we propose an inverse design optimization algorithm initialized with conformal flattening. Our algorithm minimizes the structure's strain energy in its deployed state and optimizes actuation forces so that the final deployed structure is in stable equilibrium close to the desired surface with few or no external constraints. We validate our approach by fabricating a series of physical models at various scales using different manufacturing techniques.
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Yan, Juncen. "Noncontact Defect Detection Method of Automobile Cylinder Block Based on SVM Algorithm." Mobile Information Systems 2022 (August 29, 2022): 1–11. http://dx.doi.org/10.1155/2022/5849422.
Testo completoAbstract (sommario):
Based on the problems encountered in the gateway system, this article developed the SVM algorithm support vector machine auxiliary system based on the function of the hybrid network gateway to help the gateway dynamically adjust its operating status to ensure the stability of the gateway system and the real-time internal data. This paper studies the noncontact defect detection system of automobile cylinder block on the basis of the SVM algorithm. There are many thin holes in the wall of automobile engine cylinder block, the structure is complex, and the processing is easy to deform. In order to solve the problem of deformation of the automobile engine cylinder block during the milling process, this paper uses a combination of simulation and experiment to analyze the clamping deformation and milling deformation during the machining of the top surface of the automobile cylinder block and proposes the control of the milling deformation profile error measure. Aiming at the problems of backward detection technology, low detection efficiency, and low detection accuracy for the detection of defects on the inner surface of the master cylinder of automobile brakes, this paper uses the machine vision technology to choose the noncontact method of measurement. The use of laser nonultrasonic contact systems is not limited to workpieces having regular shapes, such as planes and cylinders. It is limited to workpieces with regular shapes such as planes and cylinders. In the automotive and other industrial fields, for various curved parts with free-form surfaces, nondestructive testing techniques of laser nonultrasonic contact systems are generally required to find defects. In the research of the noncontact defect detection method of the automobile cylinder block based on the SVM algorithm, this paper hopes that the detection efficiency and detection accuracy of the inner surface of the brake cylinder can be improved, and the defect location can be accurately found.
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Kasliwal, Prasad Jaychand. "Fluoroscopy-Guided Sacroiliac Joint Injection: Description of a Modified Technique." Pain Physician 19, no. 2;2 (2016): E329—E337. http://dx.doi.org/10.36076/ppj/2016.19.e329.
Testo completoAbstract (sommario):
Sacroiliac joint (SIJ) pathology is a common etiologic cause for 10 – 27% of cases of mechanical low back pain (LBP) below the L5 level. In the absence of definite clinical or radiologic diagnostic criteria, controlled blocks of the SIJ have become the choice assessment method for making the diagnosis of SIJ pain. The SI joint is most often characterized as a large, auricular-shaped, diarthrodial synovial joint. In reality, its synovial characteristic is limited only to the distal third and anterior third. In SIJ interventions, the lateral view has been underutilized. In our technique, we used the lateral view to create a three-dimensional view of the SIJ to aid in gauging the accurateness of the contrast spread and to obtain a precise block. After obtaining appropriate fluoroscopic images, a curved tip spinal needle was directed into the inferior aspect of the SIJ using a posterior approach. As the needle contacts firm tissues on the posterior aspect of the joint, position of the needle tip is checked using lateral fluoroscopy. In the lateral view, the needle tip position is manipulated to keep it in the anterior third of the SIJ and contrast is injected. Our criteria for accurate SIJ block, in posteroanterior (PA) view, is the injection of the contrast medium should outline the joint space and the contrast medium should be seen to travel cephalad along the joint line. In the lateral view, the contrast medium most densely outlines the parameter of the joint. We have utilized this method with good effect in approximately 30 cases over one year. Out of 30 cases, needle position and contrast spread was satisfactory in 28 and 27 cases, respectively. So satisfactory needle placement and contrast spread was in 93% and 87% cases. Pain relief of 80% or more after intra-articular injection of local anaesthetic was seen in 50% (15 of 30) patients; pain relief of 50 – 79% was witnessed in 30% (9 of 30) patients. Thus, pain decreased 50% or more in 80% (24 of 30) of the joints. Out of 24 joints where we got satisfactory needle position and contrast spread, 23 joints got more than 50% relief. Thus, if needle position and contrast spread is satisfactory as per the criteria, pain relief of 50% or more was in 96% (23 of 24) of joints. There are few possible limitations with this study like difficulty to go up to the anterior third of the SIJ, it may be more painful as a narrow joint line has to be travelled in depth, sciatic numbness due to drug leak, or injuring the pelvic structure. Advantages of this method are that depth and level of the needle tip for a SIJ block is described for the more precise block. This will reduce false positive and false negative results, i.e., sensitivity and specificity of SIJ blocks and results for diagnostic blocks become more reliable. It will also reduce the chances of a case getting abandoned due to inappropriate contrast spread obscuring the fluoroscopic landmarks. As we know the depth of the needle, the chances of injuring pelvic structures become less and safety improves. Key words: Sacroiliac joint, low back pain, contrast dye, fluoroscopy, lateral view, pain management, SI joint block, modified technique
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Smith, G. D. W., A. Cerezo, and S. Poulston. "Atom probe studies of catalyst surfaces: structure and chemistry at atomic level." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 420–21. http://dx.doi.org/10.1017/s0424820100138476.
Testo completoAbstract (sommario):
The imaged (apex) region of a field ion microscope (FIM) specimen is sharply curved and has a radius of less than lOOnm. It is thus a reasonably good "model" for one half of a single particle of a metallic catalyst. FIM images show good detail of steps, ledges and kink site atoms (Fig. 1). When combined with a time-of-flight mass spectrometer to form an atom probe (AP), single atom chemical identification becomes possible. The FIM-AP combination has considerable value for the study of heterogeneous catalysts and catalytic reactions, but there are problems due to the high field acting on the specimens during observation, and the need to work in a vacuum environment. The most important applications to date have involved studies of the surface of the catalyst material, and of relatively non-labile adsorbates. However, new developments in AP instrumentation have opened the prospect of seeing catalytic reactions occurring on the atomic scale, and analysing the intermediate reaction products in both spatially- and time-resolved modes with high precision. Two main lines of development have contributed to this exciting prospect. Block and co-workers in Berlin produced the Pulsed Field Desorption Mass Spectrometer (PFDMS). In this instrument, a high electric field is initially applied to a FIM specimen in the presence of a reactive gas mixture. The specimen apex is cleaned by raising the field to a level sufficient to produce field evaporation, and then the field is dropped to zero to allow gas adsorption and reaction to occur.
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Cascardi, Alessio, Francesco Micelli, and Maria Antonietta Aiello. "An Innovative Construction Technique for Curved Structures." Applied Sciences 10, no. 13 (2020): 4465. http://dx.doi.org/10.3390/app10134465.
Testo completoAbstract (sommario):
In the present paper, an innovative, recently patented technique for the construction of a curved structural member without scaffolds is proposed and illustrated. It consists of a Hinged Lifting Arch (HLA), using Fiber-Reinforced Polymer (FRP) bonded strips. In detail, a series of blocks are cut following an arch geometry and then aligned on the ground floor to bond a composite on their top surface. Moreover, impregnation of the polymeric adhesive is not allowed at the extremities of each block. The fiber sheet is applied continuously along the entire extrados. In this context, hinges are introduced, and the FRP-connected blocks can easily rotate in the opposite direction around the contact ends (i.e., hinges). Finally, the middle block is lifted up, and the arch takes the desired shape. Moreover, an analytical model is proposed and discussed for designing the proper aspect ratio of the blocks in order to ensure full mutual contact when the HLA is completely lifted. The advantages of the proposed technique relate to the absence of scaffolds and improved seismic strength against horizontal loads, thanks to the presence of the FRP, which limits the occurrence of hinges at the extrados.
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Heuser, J. "Effects of cytoplasmic acidification on clathrin lattice morphology." Journal of Cell Biology 108, no. 2 (1989): 401–11. http://dx.doi.org/10.1083/jcb.108.2.401.
Testo completoAbstract (sommario):
Reducing the internal pH of cultured cells by several different protocols that block endocytosis is found to alter the structure of clathrin lattices on the inside of the plasma membrane. Lattices curve inward until they become almost spherical yet remain stubbornly attached to the membrane. Also, the lattices bloom empty "microcages" of clathrin around their edges. Correspondingly, broken-open cells bathed in acidified media demonstrate similar changes in clathrin lattices. Acidification accentuates the normal tendency of lattices to round up in vitro and also stimulates them to nucleate microcage formation from pure solutions of clathrin. On the other hand, several conditions that also inhibit endocytosis have been found to create, instead of unusually curved clathrin lattices with extraneous microcages, a preponderance of unusually flat lattices. These treatments include pH-"clamping" cells at neutrality with nigericin, swelling cells with hypotonic media, and sticking cells to the surface of a culture dish with soluble polylysine. Again, the unusually flat lattices in such cells display a tendency to round up and to nucleate clathrin microcage formation during subsequent in vitro acidification. This indicates that regardless of the initial curvature of clathrin lattices, they all display an ability to grow and increase their curvature in vitro, and this is enhanced by lowering ambient pH. Possibly, clathrin lattice growth and curvature in vivo may also be stimulated by a local drop in pH around clusters of membrane receptors.
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Holleran, Elizabeth A., Gladys Gray-Board, Erika L. F. Holzbaur, and Lee D. Peachey. "Fluorescence, Confocal, and Intermediate Voltage Electron Microscopy of Centractin Localization in Transfected PtK2 Cells." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 28–29. http://dx.doi.org/10.1017/s0424820100162600.
Testo completoAbstract (sommario):
Centractin (Arp 1) is an actin-related protein that shares 53% sequence identity with conventional actin and is predicted to have a similar core structure for nucleotide binding. Biochemical studies of centractin, named for its apparent localization to the centrosome, reveal that it is a member of a stable macromolecular complex, dynactin. The dynactin complex consists of at least 9 polypeptides and has been implicated in activating dynein mediated vesicle transport along microtubules. Ultra-structural analysis, by rotary shadowing electron microscopy with antibody decoration, reveals that within the context of the dynactin complex, centractin forms a 37 nm filament resembling the structure of an actin filament with capping protein and p62 localizing to opposite ends.We have used transient transfection assays to investigate the effects of overexpression of centractin in cells. Mammalian PtK2 cells were transiently transfected with centractin cloned in the pcDNA3 vector under the control of a CMV promoter. The cells were transfected for 24 hours using Ca2+/DNA co-precipitates. The transfection efficiency was as high as 41 % as determined by direct counting of immunostained cells. Cells were fixed at time points ranging from 18 to 24 hours post washing using 1% formaldehyde plus 1% Triton X-100 (5 min), 0.05% glutaraldehyde (5 min), 1 % formaldehyde (5 min), and 0.05% sodium borohydride to block free aldehyde groups (3×5 min). Immunofluorescence employed an affinity-purified, rabbit polyclonal antibody to centractin followed by a Texas Red-labeled secondary antibody. Epifluorescence microscopy revealed that all of the cells overexpressing centractin contained centractin structures with novel morphology. Two distinct patterns were observed consistently: filamentous centractin localized throughout the cytoplasm (Figure la) and perinuclear centractin accumulations (Figure lb). The perinuclear accumulations appear to be highly three dimensional and curved in structure (confirmed by confocal microscopy), and often have associated filamentous structures (Figure lb). The addition of 33 micromolar nocodozole (30 min. at 4°C) to the transfected cells results in thinner centractin filaments (Figure lc).
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Sheikhi, Sara, Mohammad Shojaeifard, and Mostafa Baghani. "Finite Bending and Straightening of Hyperelastic Materials: Analytical Solution and FEM." International Journal of Applied Mechanics 11, no. 09 (2019): 1950084. http://dx.doi.org/10.1142/s1758825119500844.
Testo completoAbstract (sommario):
In this research, an incompressible, isotropic, nonlinear elastic rectangular block and a circular cylindrical sector are studied under bending and straightening moments, respectively. Analytical approaches are presented on implementing of the left Cauchy–Green tensor and Cauchy stresses. In addition, finite element analysis of both problems is carried out using UHYPER user-defined subroutine in ABAQUS to verify the analytical methods. Four different invariant-based strain energy functions, including neo-Hookean, Mooney–Rivlin, Arruda–Boyce, and recently proposed polynomial Exp-Exp models, are examined, and the results are compared. Material parameters of silicon rubber for the strain energy functions are identified by applying an optimization procedure. Finite element method results confirmed the analytical approach with great compatibility. Results showed that the length of the unbent beam does not affect the stress. Likewise, the initial angle of curved structure does not affect the unbending moment and stresses. Moreover, the Exp-Exp model had a slightly different result rather than other strain energies, which means that this model is more conservative than its counterparts. Furthermore, the Exp-Exp strain energy function is calibrated for tissue-like phantom and is compared with experimental data.
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Xiao, Zhang, and Kang Hongpu. "Pressure Relief Mechanism of Directional Hydraulic Fracturing for Gob-Side Entry Retaining and Its Application." Shock and Vibration 2021 (April 10, 2021): 1–8. http://dx.doi.org/10.1155/2021/6690654.
Testo completoAbstract (sommario):
In order to make clear the pressure relief mechanism and application effect of directional hydraulic fracturing for gob-side entry retaining, the directional hydraulic fracturing was carried out by 400 m in haulage gateway remaining along the goaf in 50108 working face of Hejiata Coal Mine. Taking this as the engineering background, a mechanical model of roof cutting was established and the pressure relief mechanism was clarified. The theoretical research shows that it is the moments of gravity FG of the curved triangular roof plate at the face end, the pressure q of the overlying soft rock, and the transverse force TCB in the “voussoir beam” structure to the left endpoint of the triangular block, that is, M F G , M q , and M T CB , which determines the roadside supporting resistance. Hydraulic fracturing can reduce the lateral cantilever length of the basic roof, thus greatly reducing the values of M F G , M T CB , and M q , and significantly reduce the roadside supporting resistance. The field test shows that the directional hydraulic fracturing technology can effectively improve the stress environment of the face end and reduce the deformation of the roadway, and it has a good application effect on the gob-side entry retaining.
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Mr. Gaurav S. Chaturvedi, Mr Gaurav S. Chaturvedi, and Dr D. B. Jasutkar Dr. D. B. Jasutkar. "To Analysis the Feasibility of Rubble Mound Sea Wall at Mumbai Costal Road Project." Journal of Advances in Science and Technology 20, no. 1 (2024): 72–77. http://dx.doi.org/10.29070/mw797y06.
Testo completoAbstract (sommario):
The impact of seawalls on nearby beaches and the dynamics of the coast has not beenadequately studied in the literature. The purpose and function of coastal buildings, particularly seawalls,are sometimes misinterpreted since, in certain situations, they actually contribute to coastal erosioninstead of safeguarding the beach as intended. By influencing the onshoreoffshore and, to some extent,the longshore sand transport, seawalls are purportedly changing the near-shore process, notably thesediment dynamics. Therefore, it is crucial to comprehend how seawalls affect the nearby beach in order toensure that installation selections are made with more knowledge. A seawall is built along the coast,maybe at the base of cliffs or dunes. A seawall is often a concrete structure with a slope its surface maybe smooth, stepped, or curved. A seawall can also be constructed as a block seawall, a rubble-moundconstruction, a steel or timber structure. The fact that the building is built to resist powerful wave actionand storm surge is a defining trait. Such rigid seawalls are frequently protected at their foot by a rubblemoundrevetment. A rubble-mound revetment and a rubble-mound seawall are quite similar, although arevetment is frequently utilised as an addition to a seawall or as a stand-alone building in less vulnerableregions. A seawall is occasionally used to refer to an exposed dike that has been reinforced to withstandwave action.This report discuss the Construction techniques of Rubble Mound Sea wall , also its types,and Failure Pattern for this the Mumbai costal road case study taken in to consideration
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Adnan, Muhammad, Faiza Khalid, and Majid Ali. "Compressive Behavior of Interlocking Plastic Blocks Structural Elements Having Slenderness." Buildings 12, no. 12 (2022): 2257. http://dx.doi.org/10.3390/buildings12122257.
Testo completoAbstract (sommario):
Earthquakes are among of the most harmful and potentially fatal natural disasters. Masonry structures in seismic zones of urban and rural areas around the world pose a threat to human life. Housing that is both affordable and earthquake-resistant in earthquake-prone areas is currently in demand in developing countries. For affordable earthquake-resistant structures in earthquake-prone areas, numerous researchers have studied mortar-free interlocking structures. Plastic blocks are used in order to reduce the mass of the overall structure. To start with, structures under gravity are explored first because more than 95% of its design life, any structure has to withstand gravity. Prototypes of interlocking plastic-block columns, solid walls, and walls with an opening are considered for making the mortar-free structures. In this study, the effect of slenderness on the behavior of interlocking-plastic-block structural elements is investigated under compressive loading by a servo-hydraulic testing machine in the laboratory. The effect of slenderness on the behavior of one and two-block-wide structural elements was investigated in terms of the stress–strain curve, energy absorption, and toughness index under compressive loadings. Correlations between the compressive strength of interlocking-plastic-block structural elements with varying thicknesses were found. Scaled-down prototypes of interlocking-plastic-block structural elements having two-block wide depicted more resistance to compressive loads than one block wide structural elements. The correlations among the one and two block wide interlocking-plastic-block columns, single and double-block-wide solid walls, and single and double-block-width walls with an opening found in this analysis were Pdc = 2.2 Psc, Pdsw = 2.9 Pssw, and Pdwo = 3.5 Pswo. This study can be applied in the future to better understand the detailed behavior of interlocking plastic blocks.
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Di Egidio, Angelo, and Alessandro Contento. "Improvement of the Dynamic and Seismic Behaviour of Rigid Block-like Structures by a Hysteretic Mass Damper Coupled with an Inerter." Applied Sciences 12, no. 22 (2022): 11527. http://dx.doi.org/10.3390/app122211527.
Testo completoAbstract (sommario):
The protection of rigid block-like structures against seismic hazards is a widely studied topic and has been achieved to different degrees with active and passive protection methods. For the protection of rigid block-like structures, this paper proposes the coupling of a rigid block-like structure, modelled as a single rigid block, with an external, auxiliary system through a hysteretic elasto-plastic device. The auxiliary system is constituted by an oscillating mass, whose inertial effects are amplified by the use of an inerter device. The auxiliary system works as a hysteretic mass damper. The elasto-plastic behaviour of the coupling device is described by the Bouc–Wen model. The mechanical model of the coupled system has two degrees of freedom, and its equations of motion can be written by following a direct approach. A preliminary analysis is performed by exciting different coupled systems and the corresponding stand-alone rigid blocks with harmonic base accelerations. Such an investigation is aimed at understanding the sensitivity of the dynamics of the coupled systems to the characteristics of the rigid blocks and auxiliary systems and is performed by comparing the frequency–response curves of the coupled systems with those of the corresponding stand-alone rigid blocks. A further analysis is performed to verify the effectiveness of the proposed protection methodology under seismic excitation. Both the harmonic and seismic analyses show that the main parameter to be tuned to achieve the protection of the rigid block-like structures is the apparent mass of the inerter device. A proper choice of such a mass improves the dynamics of the rigid block-like structures, leading to smaller oscillations for the same level of excitation.
22
Huang, Wei, Hao Zhen Wu, Guo Xin Chen, Yin Zhang, Jun Yuan Wang, and Dong Zhao. "Mechanical Properties of the Ecological Filling Blocks of the New Composite Wall Based on the Unified Strength Theory." Advanced Materials Research 250-253 (May 2011): 843–48. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.843.
Testo completoAbstract (sommario):
In order to make the new composite wall structure the group developed to adapt different regional natural conditions, and along with the demand of gradually in-depth study the damage characteristics of the new composite wall, need to research the mechanical properties of the wall filling materials. In this paper, the ZG-CSS Electronic Universal Testing Machine was used on the uniaxial compressive test of the three blocks(the mud billet block, the cotton stalk block, the recycled EPS lightweight concrete block), to analyze the failure characteristics of the blocks and the other mechanical properties, such as Poisson’s ratio, elastic modulus, then the full compressive stress-strain curves are given, and at last fitting the mathematical expression of the uniaxial compressive stress - strain curves. And this paper also gives the yield criterion based on the unified strength theory of the three ecological filling blocks.
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Huang, Wei, and Ting Zhang. "Mechanical Properties of the Ecological Filling Blocks of the New Composite Wall Based on the Unified Strength Theory." Applied Mechanics and Materials 727-728 (January 2015): 15–20. http://dx.doi.org/10.4028/www.scientific.net/amm.727-728.15.
Testo completoAbstract (sommario):
In order to make the new composite wall structure the group developed to adapt different regional natural conditions, and along with the demand of gradually in-depth study the damage characteristics of the new composite wall, need to research the mechanical properties of the wall filling materials. In this paper, the ZG-CSS Electronic Universal Testing Machine was used on the uniaxial compressive test of the three blocks(the mud billet block, the cotton stalk block, the recycled EPS lightweight concrete block), to analyze the failure characteristics of the blocks and the other mechanical properties, such as Poisson’s ratio, elastic modulus, then the full compressive stress-strain curves are given, and at last fitting the mathematical expression of the uniaxial compressive stress - strain curves. And this paper also gives the yield criterion based on the unified strength theory of the three ecological filling blocks.
24
Stepanenko, D. A., and A. N. Kindruk. "Variational Problem on Vibrations of Unequal-Thickness Rings and Its Application for Calculating Ultrasonic Vibration Concentrators." Science & Technique 23, no. 4 (2024): 295–303. http://dx.doi.org/10.21122/2227-1031-2024-23-4-295-303.
Testo completoAbstract (sommario):
The paper considers a method for calculating the natural frequencies of vibrations of unequal-thickness rings, based on application of Hamilton’s variational principle and theories of vibrations of curved beams of the Euler-Bernoulli and Timoshenko type. Solutions of the problem are represented as Fourier series providing possibility of its reduction to the system of linear algebraic equations. The problem of determining natural frequencies is reduced to a generalized problem for the eigenvalues of matrices. Based on a comparison of the numerical results obtained for an eccentric ring with the results of calculations by the finite element method, the advantages of using the Timoshenko theory are shown, including increased calculation accuracy and the possibility to identify radial and radial-flexural eigenmodes. The possibility of reducing computational costs when using the Timoshenko theory is explored by representing the determinant of the block matrix describing the problem as a product of lower-order determinants. It is shown that the relations obtained on the basis of the Euler-Bernoulli theory, in the particular case of equal-thickness ring, lead to the well-known analytical formulas for the natural frequencies of the ring oscillations. The obtained results can be used to calculate ring concentrators of ultrasonic vibrations. The advantage of the proposed method in comparison with other known approaches, for example, the harmonic balance me-thod, consists in no need for the work with differential or integral-differential equations of vibrations, which are a rather complex structure for the case of unequal-thickness rings and require the use of computationally expensive operations, for example, discrete convolution, for their solution.
25
Busko, N. A., V. K. Grishchenko, A. V. Barantsova, N. V. Gudzenko, Ya V. Kochetova, and S. N. Ostapyk. "SILICON-CONTAINING OLIGOMERIC AZOINITIATORS IN THE SYNTHESIS OF BLOCK COPOLYMERS." Polymer journal 43, no. 2 (2021): 123–32. http://dx.doi.org/10.15407/polymerj.43.02.123.
Testo completoAbstract (sommario):
The aim of the work was to develop methods for the synthesis and study of the properties of silicon-containing oligomeric azo- and polyazoinitiators based on bis-γ-hydroxypropylpolysiloxane (HPS) and bis-γ-aminopropylpolysiloxane (APS). Silicon-containing oligomeric azoinitiators using HPS were synthesized on the basis of cyclohexanone azo-bis-isobutyrohydrazone (AGN-CH) and bis-γ-hydroxypropylpolysiloxane bifunctional macrodiisocyanate (MDIHPS). MDIHPS was obtained by the interaction of GPS with 2,4 toluene diisocyanate (2,4-TDI). Oligomeric azoinitiators have been obtained, which have the structure RXR and (RX)nR, where R is a propylpolysiloxane block, X is a azo initiator block. For the synthesis of an oligomeric azo initiator based on bis-γ-aminopropyl polysiloxane (APS), a method was first developed for the synthesis of a monomeric azo initiator with terminal oxadiazolinylcarbamanate isocyanate groups (AGN-NCO) by the interaction of AGN-CH and 2,4-TDI at a molar ratio of 1: 2. On the basis of the obtained AGN-NCO and APS at a molar ratio of AGN-NCO: APS = 1: 1, an oligomeric azo initiator (OAI APS-P) was synthesized, which has the structure (RX)nR, where R is a propylpolysiloxane block, X is an azo initiator block. The structures of monomeric and oligomeric azo initiators have been studied by UV and IR spectroscopy, and the kinetic regularities of their synthesis have been calculated. On the basis of oligomeric azo initiators and styrene, block copolymers of the (AB)nA type were obtained by the method of thermal and photoinitiated radical polymerization, where A is a propylpolysiloxane block, B is an oligosyrene block with a constant value of the organosilicon block and a different size of the oligostyrene block. The structure of block copolymers was investigated by IR spectroscopy. It was shown that during photopolymerization, oligostyrene blocks of shorter length are formed than during thermopolymerization, and possible oxidation processes. The study of relaxation transitions by DSC in oligostyrene and propylpolysiloxane blocks of the BCP showed that the common heat capacity curves are the presence of two jumps in the heat capacity at the glass transition temperatures of the polysiloxane and oligostyrene microphase. A slight shift in the glass transition temperature of polysiloxane microphases in BCP towards higher temperatures compared to the homopolymer may be associated with the effect of oligostyrene microphase. With a decrease in the length of the oligosyrene block, a low-temperature shift in the glass transition temperature of oligostyrene blocks relative to the homopolymer and a depression of ∆Cp,2 are observed, which is associated with the suppression of mobility in oligodienic microphases by less mobile propylpolysiloxane blocks.
26
Bandopadhyay, Somdeb, and Hsien Shang. "SADHANA: A Doubly Linked List-based Multidimensional Adaptive Mesh Refinement Framework for Solving Hyperbolic Conservation Laws with Application to Astrophysical Hydrodynamics and Magnetohydrodynamics." Astrophysical Journal Supplement Series 263, no. 2 (2022): 32. http://dx.doi.org/10.3847/1538-4365/ac9279.
Testo completoAbstract (sommario):
Abstract We report the development of a nested block-structured adaptive mesh framework to solve multidimensional, time-dependent hyperbolic equations encountered in astrophysics. An approach based on a tabular list is used to construct variants of Hilbert space-filling curves in an iterative fashion to maintain the connectivity of locally refined mesh configurations using a doubly linked list. Modifications are made to conventional boundaries of computational blocks to aid the adaptive mesh. We also describe a well-defined, computationally efficient data structure to hold self-similar mesh units for this purpose. The flexibility of this code is demonstrated by the performance of various Riemann solvers implemented in this computational framework.
27
Jeter, Britton, Avery E. Broderick, and Roman Gold. "Differentiating disc and black hole-driven jets with EHT images of variability in M87." Monthly Notices of the Royal Astronomical Society 493, no. 4 (2020): 5606–16. http://dx.doi.org/10.1093/mnras/staa679.
Testo completoAbstract (sommario):
ABSTRACT Millimetre-wavelength very long baseline interferometric (mm-VLBI) observations of M87 by the Event Horizon Telescope (EHT) should provide a unique opportunity to observe and characterize the origins of jet variability already seen at longer wavelengths. Synchrotron spot models have been used to model variability near black holes; this work extends these by allowing spots to shear and deform in the jet velocity field. Depending on the position of the spot, shearing forces can significantly alter the structure of the spot, producing distinct signals in reconstructed images and light curves. The maximum intensity of the shearing spot can vary by as much as a factor of 5 depending on the spot azimuthal launch position, but the intensity decay time depends most significantly on the spot radial launch position. Spots launched by a black hole-driven jet exhibit distinct arc structures in reconstructed images, and exhibit brighter and shorter lived enhancements of the light curve. Spots launched by a wind-driven jet have exhibit much simpler structures in the image, and longer lived light-curve enhancements than spots launched by a black hole-driven jet.
28
Guo, Wen, Bin Jia, Chun Tao Zhang, Xiao Liu, and Shun Feng Liu. "Low Cycle Test Research on Seismic Performance of Recycled Concrete Block Wall." Applied Mechanics and Materials 548-549 (April 2014): 1712–15. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1712.
Testo completoAbstract (sommario):
The use of concrete aggregate from earthquake damaged building to make blocks which needed for post-disaster reconstruction has brought the social, environmental, economic and other benefits, at the same time respond to the basic state policy of low carbon energy saving. At home and abroad currently focused on the materials properties of recycled aggregate and recycled concrete block basic physical mechanics to study, but research for the material block wall structure performance is less, the research for the wall shear strength and anti-seismic performance of this kind of wall is of great significance. Based on the recycled concrete aggregate from Mianyang, Sichuan where is disaster area to make three hole hollow block wall (no reinforcement) to perform low cycle experiment, collecting four samples, and achieved anti-seismic indicators such as the hysteresis curves, skeleton curves of recycled concrete block wall, analyzes the influence of the axial pressure, the loading method on seismic performance of block wall.
29
Nakano, T. "Effects of Cell Structure on Water Sorption for Wood." Holzforschung 57, no. 2 (2003): 213–18. http://dx.doi.org/10.1515/hf.2003.031.
Testo completoAbstract (sommario):
Summary Contributions of the cell structure of wood to water sorption were examined using the chemical potential change induced by restrained swelling. Thermodynamic analysis revealed that this potential was proportional to the product of moisture content and the bulk modulus of the restraining region in the wood. The modulus of the restricting region, which was calculated from isotherm curves of wood powder and block samples by using the thermodynamically derived relationship, was near that obtained from the swelling strain and stress in the cross section for whole wood. These results demonstrated that S1 and S3 layers in the cell wall, where thin crystal threads called microfibrils are wound helically in the circumference, act to resist swelling so that the isotherm curve of the block sample was lower than that of wood powder.
30
Gao, Wenwei, Hairong Yang, Le Wang, and Ruilin Hu. "Numerical Simulations of the Soil–Rock Mixture Mechanical Properties Considering the Influence of Rock Block Proportions by PFC2D." Materials 14, no. 18 (2021): 5442. http://dx.doi.org/10.3390/ma14185442.
Testo completoAbstract (sommario):
Soil-rock mixtures (S-RMs), as a kind of special engineering geological material, need to be studied because of the special structure and complex movement mechanism of their rock blocks, their physical and mechanical properties, and the factors underlying rock block movement in the process of their deformation and failure. In this paper, a series of discrete-element numerical models are constructed in particle flow code software (PFC2D). First, the random structure numerical models of S-RMs with different rock block proportions are established. Then, the parameters of the soil meso-structure are inversed by the biaxial simulation test, and a series of biaxial compressive tests are performed. The characteristics of stress and strain, deformation and failure, and rock block rotation and energy evolution are systematically investigated. The results show the following. (1) As the rock block proportion (confining pressure 0.5 MPa) increases, the peak strength of increases, the fluctuations of the post-peak become more obvious, and the dilatancy of the sample increases. (2) As the rock block proportion increases, the width of the shear band increases, the distribution of cracks becomes more complex and dispersed, and the range of the shear zone increases. (3) The number of rock blocks with rotation also increases significantly as rock block proportion increases, and the rotation angles are mostly between −5° and 5°. (4) The strain energy of S-RMs with different rock block proportions follows the same change rule as axial strain, showing a trend of first increasing and then decreasing, like the stress–strain curve.
31
Zhou, Ji Jun, Huai Fu, Yue Zhang, Yan Li, and De Zhang. "Strength Attenuation and Post Failure Behaviour of Fine Sandstone." Advanced Materials Research 446-449 (January 2012): 3538–43. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.3538.
Testo completoAbstract (sommario):
Three types of physical tests were designed to study post failure behaviour and strength attenuation of fine sandstone. Tests include rock compression test, rock unloading test and rock block shear test. The stress-strain curves at different confining pressures had been obtained as well as axial strain-lateral strain curves. The differences of axial strain-lateral strain curves exhibit that stress peak point and the point of fault formation are apparently different for the rock. After the fault is generated, fractured rock slides on the fault surfaces, while confining pressure, material strength and structure effect decide the post failure behaviour. Damaged rock specimens were poured in concrete specimens as well as irregular blocks. Material strength of rock blocks was attained. Shear strength gradually attenuates with unloading points close to the peak. Past the stress peak, rock blocks from fractured rock still have considerable material strength. It is shown that there are differences of strength parameters obtained from direct shear test and triaxial test.
32
Baraldi, Daniele, Claudia Brito De Carvalho Bello, Antonella Cecchi, and Filippo Ubertini. "Refined Rigid Block Model for In-Plane Loaded Masonry." Advances in Civil Engineering 2020 (September 29, 2020): 1–13. http://dx.doi.org/10.1155/2020/8844759.
Testo completoAbstract (sommario):
In this work, a refined rigid block model is proposed for studying the in-plane behavior of regular masonry. The rigid block model is based on an existing discrete/rigid model with rigid blocks and elastoplastic interfaces that already proven its effectiveness in representing masonry behavior in linear and nonlinear fields. In this case, the proposed model is improved by assuming rigid quadrilateral elements connected by one-dimensional nonlinear interfaces, which are adopted both to represent mortar (or dry) joints between the blocks and also to represent inner potential cracks into the blocks. Furthermore, the softening behavior of interfaces in tension and shear is taken into account. Several numerical tests are performed by considering masonry panels with regular texture subjected to compression and shear. Particular attention is given to the collapse mechanisms and the pushover curves obtained numerically and compared with existing numerical and laboratory results. Furthermore, the numerical tests aim to evaluate the applicability limits of the proposed model with respect to existing results.
33
Hook, Kristian, Jordan Cheer, and Stephen Daley. "Acoustic Black Holes in Curved Plates." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no. 5 (2023): 2590–97. http://dx.doi.org/10.3397/in_2022_0364.
Testo completoAbstract (sommario):
Acoustic Black Holes (ABHs) have been shown to produce significant vibration damping in both beams and flat plates. However, it is interesting to determine how more complex structures with singularly curved surfaces are damped by the addition of ABHs. Therefore, this paper presents an investigation into three different ABH designs that can be implemented into a curved plate. The performance of each ABH design is compared in terms of the global structural response of the curved plate.
34
Li, Bin, Wei Huang, Bin Luo, and Guoxin Chen. "Cycle behaviour of precast composite wall with different ecological filled blocks." Advances in Structural Engineering 22, no. 2 (2018): 297–310. http://dx.doi.org/10.1177/1369433218785212.
Testo completoAbstract (sommario):
This article aims at experimentally investigating a cycle behaviour of a new lateral force-resisting structural system, that is, precast composite walls with ecological filled blocks. For this purpose, a total of five low cyclic loading tests were conducted for the 1:2-scaled precast composite wall specimens with five different kinds of ecological filled blocks, namely, the wheat straw fibre raw soil–based block, the recycled expanded polystyrene lightweight concrete block, the wheat straw fibre cement–based block, the autoclaved aerated concrete block and the cotton straw block. In the test, the failure patterns, hysteretic loops, characteristic points, skeleton curves, ductility and relative deformation, stiffness degradation and energy dissipation capacity of the tested specimens were obtained and further analysed. The test results show that (1) the failure modes and mechanisms of the tested specimens are primarily affected by the strength of the filled blocks and the connection performance of the concrete ribbed grids; (2) the filled blocks, ribbed grids and the concealed frame can work cooperatively and interact and they play roles in the three stages of elastic, elastic–plastic, and ultimate destruction in turn; (3) the compressive strength, crack resistance, modulus of elasticity of filled blocks and bonding capacity with the ribbed grids are the main factors affecting the characteristic point, displacement ductility, stiffness degradation and other seismic performance index of the precast composite wall; (4) the five wall specimens have different energy dissipation capacities with the increase of displacement and also have the strong ability to resist collapse, which reflect the precast composite walls’ good behaviour in terms of earthquake resistance.
35
D'Angela, Danilo, Gennaro Magliulo, and Edoardo Cosenza. "Incremental dynamic analysis of rigid blocks subjected to ground and floor motions and shake table protocol inputs." Bulletin of the New Zealand Society for Earthquake Engineering 55, no. 2 (2022): 64–79. http://dx.doi.org/10.5459/bnzsee.55.2.64-79.
Testo completoAbstract (sommario):
This paper reports the results of an extensive campaign of incremental dynamic analyses (IDA) of rigid rocking blocks under various loading histories, including real ground/floor motions and shake table testing protocol loading histories. Several block geometries are investigated considering various size and slenderness combinations representative of building contents, monumental elements, art objects, components of critical facilities, and other unanchored elements. The spectral response of the block to different loading histories is firstly assessed by highlighting the characteristics of the different seismic input sets. Dimensionless acceleration- and velocity-based parameters are considered as intensity measures, and the block rotation normalized considering the critical angle (i.e., dimensionless rocking amplitude) is assumed as an engineering demand parameter. The IDA curves are evaluated, and the dynamic response of the blocks is characterized in terms of: (a) type of loading history, (b) intensity measure, and (c) block geometry. New information and technical insights are presented regarding the assessment of seismic response of structural and nonstructural rocking systems. The dynamic response of the blocks subjected to the investigated protocols is found to be not always compatible with the capacities related to real ground/floor motions, often producing non-conservative estimations. The discrepancy identified between the block responses associated with the protocol inputs and real motions is found to be significantly affected by both block geometry and intensity measure.
36
Joyce, George A., and William M. Henry. "Modeling the Equilibrium Compressed Void Volume of Carbon Black." Rubber Chemistry and Technology 79, no. 5 (2006): 735–64. http://dx.doi.org/10.5254/1.3547964.
Testo completoAbstract (sommario):
Abstract In this study, a broad range of furnace carbon blacks from very low to very high structure and fineness were evaluated for compressed void volume, colloidal and in-rubber properties. Compressed void volume measurements were investigated over applied pressures of approximately 18–159 MPa using a commercially available instrument. The void volume data was statistically modeled using logarithmic pressure curves, exponential energy curves and an inverse variable root curve. Parameters generated from the void volume models were analyzed using advanced non-linear multiple regression resulting in strong relationships to crushed oil absorption numbers and in-rubber properties. A comparison of void volume and oil absorption numbers indicates the void volume method offers a significant improvement in describing carbon black structure. The relationship between void volume and parameters related to rubber reinforcement found in this work is a confirmation that compressed void volume is more specific to primary structure than oil absorption numbers. Compressed void volume should provide the carbon black industry a faster, more meaningful and lower cost structure characterization than oil absorption methods.
37
Wu, Dongyue, Hui Su, Shilin Wang, and Wei Chen. "Experimental test for mechanical properties of new tenon composite wall using thermal self-insulation block." Advances in Structural Engineering 24, no. 1 (2020): 79–89. http://dx.doi.org/10.1177/1369433220944508.
Testo completoAbstract (sommario):
Concrete hollow blocks have the advantages of simplified construction, reduced construction time, and better thermal performance, and can thereby achieve energy conservation in building engineering and significantly improved thermal and mechanical performance. A new tenon composite block is presented to achieve better self-thermal insulation and mechanical performance by integrating thermal materials into blocks. The tenon composite block application requires satisfying mechanical and seismic performance. Therefore, to prove the mechanical and seismic performance of the tenon composite block, a low cyclic loading test was performed on two self-thermal insulation wall specimens: the tenon composite block and the “Martha” block (used as the comparison specimen). The crack distributions, failure modes, force–displacement data expressed using hysteresis and skeleton curves, mechanical parameters of strengths, displacements, ductility coefficients, stiffness degradations, and equivalent viscous damping coefficients of the two specimens were analyzed in the low cyclic loading test. By analyzing the specimen crack distributions and failure modes, the tenon composite block was proven capable of effectively connecting the heat insulation and loading bearing parts. The differences in the force–displacement data and the mechanical parameters between the tenon composite block and “Martha” block specimens, such as the higher strength and stiffness of the tenon composite block specimen and similar ductility performance with the widely applied “Martha” specimen, were mainly caused by the size differences between the tenon composite block and “Martha” specimens. Finally, suggestions for tenon composite block applications are proposed to overcome the limitations of the tenon composite block’s ability to consume seismic energy.
38
Aoyagi, Takeshi. "High-throughput prediction of stress–strain curves of thermoplastic elastomer model block copolymers by combining hierarchical simulation and deep learning." MRS Advances 6, no. 2 (2021): 32–36. http://dx.doi.org/10.1557/s43580-021-00008-1.
Testo completoAbstract (sommario):
Abstract We achieved high-throughput prediction of the stress–strain (S–S) curves of thermoplastic elastomers by combining hierarchical simulation and deep learning. ABA triblock copolymer with a phase-separated structure was used as a thermoplastic elastomer model. The S–S curves of the ABA triblock copolymers were calculated from the hierarchical simulation of self-consistent field theory calculations and coarse-grained molecular dynamics simulations. Because such hierarchical simulations require considerable computational resources, we applied a deep learning technique to accelerate the prediction. Sets of phase-separated structures and the S–S curves obtained from the hierarchical simulation were used to train a 3D convolutional neural network. Using the trained network, we confirmed that the predicted S–S curves of the untrained structures accurately reproduced the simulation results. These results will enable us to design novel polymers and phase-separated structures with desired S–S curves by high-throughput screening of a wide variety of structures. Graphic abstract
39
Awayo, Daniel Dibaba. "Seismic Fragility Analysis of Hollow Concrete Block Infilled Reinforced Concrete Buildings." International Research Journal of Innovations in Engineering and Technology 06, no. 12 (2022): 52–59. http://dx.doi.org/10.47001/irjiet/2022.612008.
Testo completoAbstract (sommario):
Masonry infills are usually treated as nonstructural elements in buildings, and their interaction with the bounding frame is often ignored in analysis and design of reinforced concrete structures. The main aim of this study is to develop a seismic fragility curves showing the probability of exceeding a damage limit state for a given structure type subjected to a seismic excitation. For the purpose of this study, three distinct buildings namely, seven-story, eleven-story and sixteen-story, with typical floor plan were proposed as the case study. Each building cases are explicitly modeled as a bare frame and HCB infilled model with varying percentage of infill configurations. All building models under the case study were analyzed using Seismo-Struct software to assess seismic vulnerabilities. Non-linear dynamic time history and pushover analysis were employed to generate fragility curves. 30 generated artificial accelerograms were employed in the nonlinear dynamic time history analysis. Accordingly, for developing a fragility curve, nonlinear dynamic analyses of 30 building models for each case are conducted and the maximum roof displacement (ID) for each ground motion is recorded. Results of the study showed that bare frame has a highest probability of failure and building models with a larger percentage of infill configurations have lesser failure probability than slightly infilled building models. Basically these infills have significant contribution in arresting large lateral deflections and results in lower and most tolerable story displacements under excited earthquake motion and eventually reducing the structure’s probability of failure at life safety and collapse prevention limit states
40
Paneru, Yagya Raj, and Pratikshya Chalise. "Community Structure, Regeneration Status and Tree Biomass of Shorea robusta Gaertn. in Charpala Community Forest, Rupandehi District, Central Nepal." Journal of Plant Resources 20, no. 1 (2022): 83–92. http://dx.doi.org/10.3126/bdpr.v20i01.56589.
Testo completoAbstract (sommario):
Sal is a multipurpose tropical tree that grows as the dominant plant species in Nepal’s lowlands. A comparative study of the Sal population structure was carried out in two blocks of Charpala Community Forest, Rupandehi. A total of 161 species of vascular plants, belonging to 135 genera and 69 families, were recorded, where Fabaceae (26 species) was the dominant family. Densities of Sal trees, saplings, and seedlings per hectare were 4000, 1945, and 742 respectively. A reverse J-shaped curve in the population structure of Block 1 indicated active natural regeneration. However, in Block 2, the lower densities of seedlings and saplings, and the higher densities of intermediate diameter classes indicated insufficient spontaneous regeneration. Average tree biomass and carbon stocks were 522.49 Mg/ha-1 and 245.57 Mg/ha-1, respectively. While Block 2 outperformed Block 1 in terms of tree density, carbon stock, and biomass, Block 1 had the higher density of seedlings and saplings, which improved the regeneration status of that site. Increased demand for lumber for construction has put existing Sal strands in Nepal under pressure. Therefore, a detailed study of its population makeup and natural renewal is crucial.
41
Osman, Bashir H., and Zhongfan Chen. "Experimental Studies on the Behaviors of New Energy-Saving Concrete Self-Insulating Load-Bearing Block Wall under Low-Cycle Cyclic Loading." Advances in Materials Science and Engineering 2018 (October 4, 2018): 1–16. http://dx.doi.org/10.1155/2018/4214532.
Testo completoAbstract (sommario):
Masonry walls are usually designed to resist the effect of lateral and gravity loads resulting from wind or earthquake excitations. This research aimed at investigating the inelastic behavior of a new energy-saving concrete self-insulating load-bearing block wall (ECSLBW) under in-plane cyclic loading. To provide stronger bond between the concrete block units better than the ordinary concrete masonry units, a new masonry system of concrete blocks with special configurations was made. In this experiment, three new self-insulated block wall specimens were designed, manufactured, and tested. Furthermore, self-supporting structural column-ring beam structure system was used to observe the failure mode of the walls. Moreover, the mechanical properties and seismic indexes of the walls under lateral low-cyclic loading were analyzed, including hysteretic and skeleton curves, stiffness degradation, ductility, and energy losses. The results showed that the new energy-saving block wall can meet the seismic shear calculation under 8-degree rare earthquake and meet the antiseismic fortification target in 8-degree area. Furthermore, self-contained system can greatly improve the seismic shear capacity of the wall. Finally, the seismic shear capacity of the concrete column block masonry was calculated, and the technical application method of block masonry structure was recommended.
42
Cool, Vanessa, Lucas Van Belle, Claus Claeys, Elke Deckers, and Wim Desmet. "(Generalized) Bloch mode synthesis for the fast dispersion curve calculation of 3D periodic metamaterials." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 4 (2021): 2102–13. http://dx.doi.org/10.3397/in-2021-2052.
Testo completoAbstract (sommario):
Metamaterials, i.e. artificial structures with unconventional properties, have shown to be highly potential lightweight and compact solutions for the attenuation of noise and vibrations in targeted frequency ranges, called stop bands. In order to analyze the performance of these metamaterials, their stop band behavior is typically predicted by means of dispersion curves, which describe the wave propagation in the corresponding infinite periodic structure. The input for these calculations is usually a finite element model of the corresponding unit cell. Most common in literature are 2D plane metamaterials, which often consist of a plate host structure with periodically added masses or resonators. In recent literature, however, full 3D metamaterials are encountered which are periodic in all three directions and which enable complete, omnidirectional stop bands. Although these 3D metamaterials have favorable vibro-acoustic characteristics, the computational cost to analyze them quickly increases with unit cell model size. Model order reduction techniques are important enablers to overcome this problem. In this work, the Bloch Mode Synthesis (BMS) and generalized BMS (GBMS) reduction techniques are extended from 2D to 3D periodic structures. Through several verifications, it is demonstrated that dispersion curve calculation times can be strongly reduced, while accurate stop band predictions are maintained.
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Suresh, V., K. Ganesan, and S. Parthasarathy. "PDB-2-PB: a curated online protein block sequence database." Journal of Applied Crystallography 45, no. 1 (2011): 127–29. http://dx.doi.org/10.1107/s0021889811052356.
Testo completoAbstract (sommario):
This article describes the development of a curated online protein block sequence database, PDB-2-PB. The protein block sequences for protein structures with complete backbone coordinates have been encoded using the encoding procedure of de Brevern, Etchebest & Hazout [Proteins(2000),41, 271–287]. In the current release of the PDB-2-PB database (version 1.0), the protein entries from a recent release of the World Wide Protein Data Bank (wwPDB), which has 74 297 solved PDB entries as of 7 July 2011, have been used as a primary source. The PDB-2-PB database stores the protein block sequences for all the chains present in a protein structure. PDB-2-PB version 1.0 has the curated protein block sequences for 103 252 PDB chain entries (93 547 X-ray, 7033 NMR and 2672 other experimental chain entries). From the PDB-2-PB database, users can extract the curated protein block sequence and its corresponding amino acid sequence, which is extracted from the PDB ATOM records. Users can download these sequences either by using the PDB code or by using various parameters listed in the database. The PDB-2-PB database is freely available at http://bioinfo.bdu.ac.in/~pb/.
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Kim, Yong Tai, Tae Jun Kim, Tae Yoon Park, and Chang Doo Jang. "Welding Distortion Analysis of Hull Blocks using Equivalent Load Method Based on Inherent Strain." Journal of Ship Research 56, no. 02 (2012): 63–70. http://dx.doi.org/10.5957/jsr.2012.56.2.63.
Testo completoAbstract (sommario):
Welding deformation reduces the dimensional accuracy of ship hull blocks and decreases productivity due to the correction work. Prediction and minimizing of welding distortion at the design stage will lead to higher quality as well as higher productivity. Therefore, the development of an effective method to predict accurately the weld distortion of hull blocks considering the fabrication sequences is required. In the case of hull block welding work in shipyards, the welding process of curved stiffened plates has large amounts of workload. This paper suggests an efficient method for predicting the welding deformation of stiffened curved plates based on the inherent strain theory combined with the finite element method. The equivalent load was determined by integrating inherent strain components which are calculated in the vicinity of heat affected zone using the highest temperature and the degree of restraint. The welding distortion of curved stiffened panels under equivalent load are calculated by elastic analysis and compared with that by intensive elasto-plastic finite element analysis. It is verified that the proposed method has a high efficiency and accuracy.
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Chen, Yang, Dameng Liu, Yidong Cai, and Jingjie Yao. "Fracturing curve and its corresponding gas productivity of coalbed methane wells in the Zhengzhuang block, southern Qinshui Basin, North China." Energy Exploration & Exploitation 38, no. 5 (2020): 1387–408. http://dx.doi.org/10.1177/0144598720923820.
Testo completoAbstract (sommario):
Hydraulic fracturing has been widely used in low permeability coalbed methane reservoirs to enhance gas production. To better evaluate the hydraulic fracturing curve and its effect on gas productivity, geological and engineering data of 265 development coalbed methane wells and 14 appraisal coalbed methane wells in the Zhengzhuang block were investigated. Based on the regional geologic research and statistical analysis, the microseismic monitoring results, in-situ stress parameters, and gas productivity were synthetically evaluated. The results show that hydraulic fracturing curves can be divided into four types (descending type, stable type, wavy type, and ascending type) according to the fracturing pressure and fracture morphology, and the distributions of different type curves have direct relationship with geological structure. The vertical in-situ stress is greater than the closure stress in the Zhengzhuang block, but there is anomaly in the aggregation areas of the wavy and ascending fracturing curves, which is the main reason for the development of multi-directional propagated fractures. The fracture azimuth is consistent with the regional maximum principle in-situ stress direction (NE–NEE direction). Furthermore, the 265 fracturing curves indicate that the coalbed methane wells owned descending, and stable-type fracturing curves possibly have better fracturing effect considering the propagation pressure gradient (FP) and instantaneous shut-in pressure (PISI). Two fracturing-productivity patterns are summarized according to 61 continuous production wells with different fracturing type and their plane distribution, which indicates that the fracturing effect of different fracturing curve follows the pattern: descending type > stable type > wavy type > ascending type.
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Kumada, Takayuki, Kazuhiro Akutsu, Kazuki Ohishi, et al. "Development of spin-contrast-variation neutron reflectometry for the structural analysis of multilayer films." Journal of Applied Crystallography 52, no. 5 (2019): 1054–60. http://dx.doi.org/10.1107/s1600576719010616.
Testo completoAbstract (sommario):
The spin-contrast-variation neutron reflectometry technique was developed for the structural analysis of multilayer films. Polarized-neutron reflectivity curves of film samples vary as a function of their proton polarization (P H). The P H-dependent reflectivity curves of a polystyrene monolayer film were precisely reproduced using a common set of structural parameters and the P H-dependent neutron scattering length density of polystyrene. This result ensures that these curves are not deformed by inhomogeneous P H but can be used for structural analysis. Unpolarized reflectivity curves of poly(styrene-block-isoprene) films were reproduced using a flat free-surface model but P H-dependent polarized reflectivity curves were not. The global fit of the P H-dependent multiple reflectivity curves revealed that holes with a depth corresponding to one period of the periodic lamellae of microphase-separated polystyrene and polyisoprene domains were produced on the surface of the films, which agrees with the microscopic results. In this manner, the spin-contrast-variation neutron reflectometry technique determines the structure of multiple surfaces and interfaces in a film sample while excluding the incorrect structure that accidentally accounts for a single unpolarized reflectivity curve only.
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Liu, Zhe, Wenke Li, Lei Zhang, and Jiajing Li. "Fine Geological Modeling of Complex Fault Block Reservoir Based on Deep Learning." Wireless Communications and Mobile Computing 2022 (March 9, 2022): 1–16. http://dx.doi.org/10.1155/2022/9670311.
Testo completoAbstract (sommario):
Nowadays, people’s demand for underground mineral resources is increasing, and geological disasters have occurred frequently in recent years. Geological disasters refer to geological effects or geological phenomena that are formed under the action of natural or man-made factors, causing loss of human life and property, and damage to the environment; such as landslides, collapses, mudslides, and ground subsidence. Under such a background, people must accelerate the exploration of complex geological structures. This paper is aimed at using the methods and concepts of deep reinforcement learning. Deep learning is to learn the inherent laws and representation levels of sample data. The information obtained during these learning processes is of great help to the interpretation of data such as text and images. In this way, the fine geology of complex fault-block reservoirs is modeled and studied. Geological structures and phenomena are discussed through convolutional neural network models and computer techniques. At the same time, the multitask bird recognition network is used to extract and classify geological images, so as to construct geological model maps with different spatial structures. Finally, the quality of the fault reconstruction model, the calculation of reservoir geological simulation reserves, and the evaluation of the water injection development effect of complex fault blocks are analyzed. In the evaluation of the development effect of water injection in complex fault blocks, comparing the relationship curve between the actual comprehensive water content and the oil recovery factor with the standard curve, the comprehensive water content of the initial block increased rapidly. Through timely and dynamic water allocation and comprehensive management, the water cut rising speed is controlled. The current comprehensive water cut of the reservoir is between 60% and 80%, the actual curve is between 25% and 35%, and the estimated waterflooding recovery is about 30%.
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Scorzoni, Marco, Gian Luigi Gonnella, Emanuele Capogna, et al. "Achieving Lumbar Epidural Block Competency in Inexperienced Trainees after a Structured Epidural Teaching Model: A Randomized, Single Blind, Prospective Comparison of CUSUM Learning Curves." Anesthesiology Research and Practice 2022 (September 2, 2022): 1–6. http://dx.doi.org/10.1155/2022/1738783.
Testo completoAbstract (sommario):
Aim. The aim of this randomized, prospective study was to investigate whether the use of the structured epidural teaching model (SETM) may affect the learning curve for lumbar epidural block in novice trainees when compared with a standard teaching module. Introduction. There is a paucity of literature regarding the efficacy of teaching epidural blocks and comparisons between the different educational approaches. Method. Forty-four PGY3 anesthesia trainees were randomized to receive (study group) or to not receive (control group) the SDM (structured didactic model) before the beginning of their 6 months clinical practice rotation in labor and delivery suites. A CUSUM learning curve was built for every trainee. The scores were assigned by the staff instructor, who was unaware of the group to which the trainee belonged. Results. The number of subjects who achieved an improvement in performance was 8 trainees from the control group and 14 from the study group. The probability of achieving an improvement was higher ( p < 05 ) in the study group than in the control group, with an aOR of 3.25 (CI: 1.01; 12.1). The proportion of subjects in the study group who completed the epidural without help was 1.21 (1.05–1.41) times the proportion of subjects who completed the epidural without help in the control group. The probability of completing the epidural block without any assistance was 21% higher in the study group than in the control group ( p < 05 ). Conclusion. We have demonstrated that the use of the structured epidural teaching model (SETM) may improve the learning curve (CUSUM) for lumbar epidural block in novice, entirely inexperienced, anesthesia trainees.
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Wang, Ping, Qiang Yi, Caiyou Zhao, and Mengting Xing. "Elastic wave propagation characteristics of periodic track structure in high-speed railway." Journal of Vibration and Control 25, no. 3 (2018): 517–28. http://dx.doi.org/10.1177/1077546318787947.
Testo completoAbstract (sommario):
Wave propagation in the ordered and randomly disordered periodic track structure in high-speed railways are investigated theoretically and experimentally. Taking the CRTS-I double-block ballastless track structure in China as the research object, a theoretical model of periodic track structure is established. The rail is modelled as a Timoshenko beam considering the bending–torsional coupling. The dispersion curves of the periodic track structure are obtained according to the transfer matrix method and Bloch theory. Based on the Lyapunov exponent algorithm, the elastic wave propagation characteristics of the randomly disordered periodic track structure are further calculated and analyzed considering the random disorder of structure parameters. The obtained results show that the periodic track structure is characterized by band gaps, elastic wave propagation attenuates significantly within the band gap, and random disorder in the track structure can expand the attenuation regions. Finally, the band gap characteristics of the vertical/lateral flexural wave and torsional wave are verified respectively through an in situ experiment.
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Shindo, Ryota, and Shinji Nishiwaki. "Latest Machine Tool Structural Design Technology for Ultra-Precision Machining." International Journal of Automation Technology 14, no. 2 (2020): 304–10. http://dx.doi.org/10.20965/ijat.2020.p0304.
Testo completoAbstract (sommario):
Most machine tools comprise a combination of square blocks and plates for each body structure, which is not fully optimized. One reason for the nonoptimal design is that machine tool designers face difficulty in introducing curved structures to fulfill functional requirements. In this paper, completely new structures of the surface profile grinding machine have been developed, pursuing the ideal structure by defying fundamental design rules as well as by utilizing topology and shape optimization methods. The combination of fundamental techniques and state-of-art techniques enables lightweight structures that can achieve two-times higher resonance frequency, 40–50% space-saving, and 60–100% productivity improvement, compared to those with the conventional design.