Articoli di riviste sul tema "Assembly by densified dowels"
Segui questo link per vedere altri tipi di pubblicazioni sul tema: Assembly by densified dowels.
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-34 articoli di riviste per l'attività di ricerca sul tema "Assembly by densified dowels".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi gli articoli di riviste di molte aree scientifiche e compila una bibliografia corretta.
1
Han, Lei, Andreja Kutnar, Jakub Sandak, Iztok Šušteršič e Dick Sandberg. "Adhesive- and Metal-Free Assembly Techniques for Prefabricated Multi-Layer Engineered Wood Products: A Review on Wooden Connectors". Forests 14, n. 2 (5 febbraio 2023): 311. http://dx.doi.org/10.3390/f14020311.
Abstract (sommario):
Engineered wood products (EWPs) are being increasingly used as construction materials. EWPs are currently being made using synthetic adhesives or metal fasteners, which lead to poor recyclability and reusability. Therefore, this review paper focused on emerging adhesive- and metal-free assembling techniques including wood dowels, rotary-dowel welding, wooden nails, and dovetail joining as alternative ways of making prefabricated EWPs. This will contribute towards green construction and optimising the building process to minimise its negative impact on the environment and its inhabitants, while maximising the positive aspects of the finished structure. The respective advantages and shortcomings will be compared with those of equivalent EWPs. In general, the dowel-laminated timber (DLT) provides sufficient load-bearing capacity and even better ductility than EWPs of equivalent size, but its relatively low stiffness under a bending load limits its application as a structural element. Optimised manufacturing parameters such as dowel species, dowel spacing, dowel diameter, dowel insertion angle, dowel shape, etc. could be studied to improve the stiffness. The improved mechanical properties and tight fitting due to set-recovery of densified wood support its use as sustainable alternatives to hardwood dowels in DLT to overcome problems such as the loosening of connections over time and dimensional instability. The rotary welding technology could also enhance the strength and long-term performance of dowel-type joints, but its poor water resistance needs further investigation. The main obstacles to implementing DLT products in the market are missing technical information and design guidelines based on national codes.
2
Riggio, Mariapaola, Dusan Pauliny, Jakub Sandak e Anna Sandak. "Novel Nail-Like Wood Connectors". Advanced Materials Research 778 (settembre 2013): 647–54. http://dx.doi.org/10.4028/www.scientific.net/amr.778.647.
Abstract (sommario):
In traditional timber structures, hardwood connectors such as a nails, wedges, dowels and pegs have been used as reinforcement of carpentry joints or to fix wooden ceiling matts or floor boards. In the study reported, the possibility to rely on enhanced mechanical and technological properties of densified wood, for the production of wooden nails to be used in the repair of traditional timber structures is discussed. The wood used for connectors were domestic wood species; ash, beech, black locust and poplar. Wooden blocks were exposed to densification procedure with the purpose of increasing the materials density, dimensional stability and possibly, improve durability and selected mechanical properties. The densification ratio varied between 50 and 67%. A dedicated research has been performed in order to determine the effect of densification on the compression behavior of wood in the form of nails. The progress of pushing force during insertion of the wooden nails into wood samples was also monitored and served for insertion process control. A preliminary series of push-out tests have been carried out on timber-to-timber joints assembled with the densified nails.The results obtained show potential for using the novel wooden nail connectors for substitution or integration repair works in traditional timber systems.
3
Guan, Z. W., e P. D. Rodd. "A three-dimensional finite element model for locally reinforced timber joints made with hollow dowel fasteners". Canadian Journal of Civil Engineering 27, n. 4 (1 agosto 2000): 785–97. http://dx.doi.org/10.1139/l00-018.
Abstract (sommario):
Brittle premature failure caused by splitting parallel to the timber grain is a common failure mode in glulam joints made with solid dowel type fasteners. It is thought that this problem can be alleviated by using hollow steel dowels as the fasteners and reinforcing the timber locally in the area of the joint. In this way, by varying the wall thickness of the dowels and the thickness of the reinforcing members, a chosen combination of strength and stiffness should be attainable together with a ductile failure mode. In this paper, three-dimensional nonlinear finite element models are developed to simulate (i) the structural performance of a timber joint made with a single hollow steel dowel and (ii) a moment transmitting joint made with a number of the dowels, each type being locally reinforced by densified veneer wood. The models incorporate suitably defined elastoplasticity and orthotropic elasticity and also allow for large deformations of the joints as well as for frictional contact between the timber and the dowel. They are calibrated against physical test data from joints loaded to failure.Key words: glulam, densified veneer wood, resin injected, hollow dowel fastener, moment transmitting, ductile failure, finite element.
4
Grönquist, Philippe, Thomas Schnider, Andreas Thoma, Fabio Gramazio, Matthias Kohler, Ingo Burgert e Markus Rüggeberg. "Investigations on densified beech wood for application as a swelling dowel in timber joints". Holzforschung 73, n. 6 (26 giugno 2019): 559–68. http://dx.doi.org/10.1515/hf-2018-0106.
Abstract (sommario):
AbstractFor robotic fabrication of wooden structures, the simple, quick and tight joining of elements can be solved using swelling hardwood dowels. This topic has been the focus of the present study, and the set-recovery capacity of densified wood (dW) as dowel material was investigated. European beech was compressed in the radial direction at 103°C and 10% moisture content (MC) to a compression ratio of 40%. Multiple swelling and shrinkage cycles were applied to measure swelling behavior, swelling pressure development and combined swelling and creep under compressive loading. It has been demonstrated that dW shows increased swelling and more persisting swelling pressures than native wood (nW). The set-recovery prevents significant contact-stress relaxation over multiple cycles of MC change. Application as a structural joining element for robotic fabrication was studied by shear lap joint tests on round double-dovetail swelling dowels.
5
Ercan, Ersin, Kadir Aydin, Cansu Özder e Musa Atar. "The effect of the densification process on dowel tensile performance with different types of glues". Folia Forestalia Polonica 64, n. 4 (1 dicembre 2022): 214–25. http://dx.doi.org/10.2478/ffp-2022-0021.
Abstract (sommario):
Abstract This study was performed to determine the effects of the densification process and glue type in wood material on dowel tensile performance. For this purpose, 8 mm and 10 mm diameter dowels were obtained from black poplar (Populus nigra) and Eastern spruce (Picea orientalis L.), which were densified at 50% and 75% ratios. The dowels were bonded with PVAc and D-VTKA glue separately after drilling 18 mm deep holes in the edge of the melamine-coated particleboard. The tensile performance test was determined with the Universal test device according to TS 2475 and ASTM-D 1035 principles. As a result, Eastern spruce wood had the highest tensile performance (kg/cm2), and poplar wood had the lowest (173.66). For the dowel diameter parameter, the highest value (195.11) was found at 8 mm in diameter and the lowest value (161.05) was found at 10 mm in diameter. In terms of glue type, the highest value (185.92) was seen at PVAc while the lowest value (170.24) was seen at D-VTKA. And for the densification ratios, the highest value (191.4) was determined at 75%, while the lowest value was found in control samples at (167.4). According to the wood species, densification ratio, dowel diameter and glue type interaction, the highest value was determined at Es + d75% + 10mm + PVAc as (303.5) and the lowest value was found at P + d50% + 10mm + Dv as (110). As a result, where the dowel's high tensile performance is sought, using a 10 mm diameter dowel made from 75% densified spruce wood with PVAc glue may be advantageous.
6
Kasal, Ali, Jerzy Smardzewski, Tolga Kuşkun e Ersan Güray. "Analyses of L-Type Corner Joints Connected with Auxetic Dowels for Case Furniture". Materials 16, n. 13 (23 giugno 2023): 4547. http://dx.doi.org/10.3390/ma16134547.
Abstract (sommario):
Tests were carried out to develop and manufacture various types of auxetic dowels using 3D printing technology. These dowels were then used to connect L-type corner joint specimens for case furniture, and their strength and stiffness were analyzed through experimental, theoretical, and numerical means. In the scope of the study, eight different types of auxetic dowels including two inclusion types, two inclusion sizes, and two dowel hole diameters, as well as a reference non-auxetic dowel, were designed. Accordingly, a total of 180 specimens that included 10 replications for each group were tested; 90 were tested under tension and the remaining 90 were tested under compression. The results demonstrated that the assembly force required for the corner joints connected with auxetic dowels was significantly lower compared to non-auxetic dowels. Furthermore, the numerical and theoretical analyses yielded similar outcomes in this study. Both analyses revealed that the dowels used to connect the corner joints experienced substantial stresses during mounting and bending, ultimately leading to their failure. Upon concluding the test results, it was observed that the corner joints connected with dowels featuring rectangular inclusions exhibited superior performance when compared to those with triangular inclusions. In light of these findings, it can be concluded that further enhancements are necessary for auxetic dowels with rectangular inclusions before they can be utilized as alternative fasteners for traditional dowels.
7
O'Ceallaigh, Conan, Michael Conway, Sameer Mehra e Annette M. Harte. "Numerical Investigation of Reinforcement of Timber Elements in Compression Perpendicular to the Grain using Densified Wood Dowels". Construction and Building Materials 288 (giugno 2021): 122990. http://dx.doi.org/10.1016/j.conbuildmat.2021.122990.
8
Bocquet, J. F., A. Pizzi e L. Resch. "Full-scale industrial wood floor assembly and structures by welded-through dowels". Holz als Roh- und Werkstoff 65, n. 2 (6 febbraio 2007): 149–55. http://dx.doi.org/10.1007/s00107-006-0170-4.
9
Pakuła, Weronika, Barbara Prałat, Zbigniew Potok, Krzysztof Wiaderek e Tomasz Rogoziński. "Energy Consumption for Furniture Joints during Drilling in Birch Plywood". Polymers 16, n. 8 (10 aprile 2024): 1045. http://dx.doi.org/10.3390/polym16081045.
Abstract (sommario):
The purpose of this study is to support eco-design ideas and sustainable manufacturing techniques by examining the energy consumption related to drilling holes for different furniture connections. The experimental model is a simple piece of furniture made from birch plywood with three different types of joints. Eccentric joints, confirmat screws, and dowel measurements of energy consumption with a CNC drilling and milling machine show different values for every kind of connector. The energy consumption was measured using a portable power quality analyzer, specifically the PQ-box 150 manufactured by A:Eberle GmbH & Co. KG Nürnberg, Germany. This device likely adheres to industry standards for energy measurement, ensuring accurate and reliable results. The measurement process involved recording energy consumption at different stages of the machining process, allowing for the analysis of specific cutting work and total energy consumption for various joint types. Dowels exhibit the lowest energy consumption at 0.105 Wh for one furniture joint, confirmat screws at 0.127 Wh, while eccentric joints, despite their higher energy consumption (0.173 Wh), offer enhanced transportability and assembly flexibility of a piece of furniture. Specific cutting power for one selected piece of furniture was 227.89 J/mm3 for dowels, 190.63 J/mm3 for eccentric joints and 261.68 J/mm3 for confirmat screws.
10
Rezabeigi, Ehsan, Gabriele Griffanti e Showan N. Nazhat. "Effect of Fibrillization pH on Gelation Viscoelasticity and Properties of Biofabricated Dense Collagen Matrices via Gel Aspiration-Ejection". International Journal of Molecular Sciences 24, n. 4 (15 febbraio 2023): 3889. http://dx.doi.org/10.3390/ijms24043889.
Abstract (sommario):
Reconstituted hydrogels based on the self-assembly of acid-solubilized collagen molecules have been extensively used as in vitro models and precursors in biofabrication processes. This study investigated the effect of fibrillization pH—ranging from 4 to 11—on real-time rheological property changes during the gelation of collagen hydrogels and its interplay with the properties of subsequently biofabricated dense collagen matrices generated via automated gel aspiration-ejection (GAE). A contactless, nondestructive technique was used to characterize the temporal progression in shear storage modulus (G’, or stiffness) during collagen gelation. There was a relative increase in G′ of the hydrogels from 36 to 900 Pa with an increase in gelation pH. Automated GAE, which simultaneously imparts collagen fibrillar compaction and alignment, was then applied to these precursor collagen hydrogels to biofabricate native extracellular matrix-like densified gels. In line with viscoelastic properties, only hydrogels fibrillized in the 6.5 < pH ≤ 10 range could be densified via GAE. There was an increase in both fibrillar density and alignment in the GAE-derived matrices with an increase in gelation pH. These factors, combined with a higher G′ in the alkaline precursor hydrogels, led to a significant increase in the micro-compressive modulus of GAE-densified gels of pH 9 and 10. Furthermore, NIH/3T3 fibroblast-seeded GAE-derived matrices densified from gels fibrillized in the pH range of 7 to 10 exhibited low cell mortality with >80% viability. It is anticipated that the results of this study can be potentially applicable to other hydrogel systems, as well as biofabrication techniques involving needles or nozzles, such as injection and bioprinting.
11
Šimek, Milan, Eva Haviarová e Carl Eckelman. "The end distance effect of knock-down furniture fasteners on bending moment resistance of corner joints". Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 56, n. 2 (2008): 203–10. http://dx.doi.org/10.11118/actaun200856020203.
Abstract (sommario):
The goal of this paper is to investigate the effect of the end distance of cam lock fasteners on the bending moment resistance of knock-down corner joints. The preliminary study of knock-down furniture assembly plans was done in order to discover the manufacturers’ fastener typical usage in case construction. Laminated particleboard, cam fasteners and wooden dowels were used for specimen construction. L-shaped joint specimens 760 mm in length were tested by pressing the joint members together – also called a compression test in the angle plane. The study results showed that cam fasteners with end distance of 60 mm from the member edges perform the best.
12
Johanides, Marek, Antonin Lokaj, Pavel Dobes e David Mikolasek. "Numerical and Experimental Analysis of the Rotational Stiffness of a Timber Semi-Rigid Dowel-Type Connection". Materials 15, n. 16 (16 agosto 2022): 5622. http://dx.doi.org/10.3390/ma15165622.
Abstract (sommario):
The paper deals with the analysis of the rotational stiffness of a semirigid connection created from a system of two stands and a rung. The connection was made from glued laminated timber with metal mechanical dowel-type fasteners. Not only a common combination of bolts and dowels but also fully threaded screws were used for the connection. The aim of the research and its motivation was to replace commonly used fasteners with more modern ones, to shorten and simplify the assembly time, and to improve the load-carrying capacity of this type of connection. Each of these two types of connection was loaded to the level of 60%, 80%, and 100% of the ultimate limit state value. Subsequently, the rotational stiffness was determined for each load level after five loading and unloading cycles. This paper presents the results and comparison of the experimental testing and the numerical modeling. The obtained results were also compared with the assumption according to the currently valid standard.
13
Li, Ya Yun, Bo Li, Jing Bo Sun, Kun Peng Cai, Ji Zhou e Long Tu Li. "Direct Write Assembly of 3-Dimensional Structures with Aqueous-Based Piezoelectric Inks". Key Engineering Materials 512-515 (giugno 2012): 390–94. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.390.
Abstract (sommario):
A kind of aqueous based suspensions of lead lanthanum zirconnate titanate (PLZT) was developed for direct ink writing (DIW) assembly. Piezoelectric ceramic woodpile structures with diameter of 315-470μm were fabricated from these inks by using DIW. The preparation of aqueous based piezoelectric inks, the principle of DIW and the sintering process were systematically discussed. The ink with solids volume fraction over 70% by 1 day aging reveals shear-thinning behavior and proper viscoelastic properties, which ensures a feasible extrusion in the whole shaping process. The PLZT samples sintered at varying temperatures between 1150 oC and 1250 oC for 2h or 4 h in either air or a lead-rich atmosphere yielded various microstructures observed by scanning electron microscopy (SEM). Choosing the optimum sintering condition, the sintered products were densified with relative density exceed 98%. The test of X-ray diffraction (XRD) analysis reveals that the main phase of sintered samples is rhombohedral Pb0.93La0.07(Zr0.65Ti0.35)0.9825O3. The direct ink writing technique has advantages of good design ability and rapid forming capability, which opens up a potential route for the design and fabrication of piezoelectric devices.
14
Alvarez, Noe, Pankaj Gupta, Connor Rahm, Vandna Gupta e Chethani Ruhunage. "Carbon Nanotubes from Synthesis to Picomolar Detection Electrochemical Sensors". ECS Meeting Abstracts MA2022-01, n. 9 (7 luglio 2022): 762. http://dx.doi.org/10.1149/ma2022-019762mtgabs.
Abstract (sommario):
Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electrochemically active. A particular challenge in this field has been the ability to conduct electrochemical studies selectively at the open-ends of CNTs, without measuring contributions from the sidewalls. This talk will discuss the synthesis and assembly of CNTs into electrochemical sensor where open-ended CNTs were employed for electrochemical measurements. The assembly employs drawable CNTs that minimize sample handling and contamination, in the attempt to preserve the pristine nature of CNTs. Highly densified multiwalled carbon nanotube (HD-CNT) fibers were embedded within a polymer matrix protecting the sidewalls and limiting the reactions to the tips of the CNTs. Cyclic voltammetry was employed to examine the electrochemical properties of open-ended CNTs using a conventional bulk electrochemical cell and scanning electrochemical cell microscopy (SECCM). This assemblies have shown to detect extremely low concentrations of Pb2+ in water, neurotransmitters, NADH, furosemide (diuretic drug), and the electrodes were tested with multiple electrochemical techniques.
15
Johanides, Marek, Antonin Lokaj, Pavel Dobes e David Mikolasek. "Numerical and Experimental Analysis of the Load-Carrying Capacity of a Timber Semi-Rigid Dowel-Type Connection". Materials 15, n. 20 (17 ottobre 2022): 7222. http://dx.doi.org/10.3390/ma15207222.
Abstract (sommario):
The paper deals with the analysis of the load-carrying capacity of a timber semi-rigid connection created from a system of two stands and a rung. The connection was made from glued laminated timber with metal mechanical dowel-type fasteners. Not only a common combination of bolts and dowels, but also fully threaded screws were used for the connection. The aim of the research and its motivation was to replace these commonly used fasteners with more modern ones, to shorten and simplify the assembly time, and to improve the load-carrying capacity of this type of connection. Each of these two types of connections was loaded statically, with a slow increase in force until failure. The paper presents results of the experimental testing. Three specimens were made and tested for each type of the connection. Experimental results were subsequently compared with numerical models. The achieved results were also compared with the assumption according to the currently valid standard. The results indicate that a connection using fully threaded screws provides a better load-carrying capacity.
16
Albertin, Fauzia, Maria Pia Morigi, Matteo Bettuzzi, Rosa Brancaccio, Nicola Macchioni, Roberto Saccuman, Gianluca Quarta, Lucio Calcagnile e Daniela Picchi. "X-ray Tomography Unveils the Construction Technique of Un-Montu’s Egyptian Coffin (Early 26th Dynasty)". Journal of Imaging 8, n. 2 (7 febbraio 2022): 39. http://dx.doi.org/10.3390/jimaging8020039.
Abstract (sommario):
The Bologna Archaeological Museum, in cooperation with prestigious Italian universities, institutions, and independent scholars, recently began a vast investigation programme on a group of Egyptian coffins of Theban provenance dating to the first millennium BC, primarily the 25th–26th Dynasty (c. 746–525 BC). Herein, we present the results of the multidisciplinary investigation carried out on one of these coffins before its restoration intervention: the anthropoid wooden coffin of Un-Montu (Inv. MCABo EG1960). The integration of radiocarbon dating, wood species identification, and CT imaging enabled a deep understanding of the coffin’s wooden structure. In particular, we discuss the results of the tomographic investigation performed in situ. The use of a transportable X-ray facility largely reduced the risks associated with the transfer of the large object (1.80 cm tall) out of the museum without compromising image quality. Thanks to the 3D tomographic imaging, the coffin revealed the secrets of its construction technique, from the rational use of wood to the employment of canvas (incamottatura), from the use of dowels to the assembly procedure.
17
Saad, Ahmad S., Taha A. Ahmed e Ali I. Radwan. "In-Plane Lateral Performance of AAC Block Walls Reinforced with CFPR Sheets". Buildings 12, n. 10 (13 ottobre 2022): 1680. http://dx.doi.org/10.3390/buildings12101680.
Abstract (sommario):
This study evaluates the structural behavior of aerated autoclave concrete (AAC) blocks laterally loaded in the in-plane direction under quasi-static loading. The study started with the evaluation of the basic physical properties of the AAC blocks, including its structural properties (individually and as part of an assembly), followed by large-scale testing of two (half-scaled) walls constructed with commercially available AAC blocks. The first wall was unreinforced, similar to the commonly used construction technique for low-rise houses where AAC blocks are utilized. The second one was internally reinforced with short dowels connecting the foundation to the walls through their lower block rows and externally reinforced with carbon-fiber-reinforced polymer (CFRP) sheets through the entire wall height. The reinforcement scheme was conducted in such a way that does not delay construction time. Reinforcing the wall significantly increased the strength of the wall in the in-plane direction. The reinforced wall exhibited increased initial stiffness, higher ductility, and larger energy dissipation, in addition to a change in the failure mode. The unreinforced wall failure mode was dominated by blocks sliding, while the reinforced wall failure was dominated by compressive shear failure with wall uplifting. The findings of this study can be implemented to increase the lateral strength of unreinforced new houses and can also be extended to strengthen existing houses built with unreinforced AAC blocks.
18
Bertetto, Amedeo Manuello, e Federico Riberi. "Form-finding of pierced vaults and digital fabrication of scaled prototype". Curved and Layered Structures 8, n. 1 (1 gennaio 2021): 210–24. http://dx.doi.org/10.1515/cls-2021-0020.
Abstract (sommario):
Abstract The new serious consideration to masonry and non-metallic structures evidenced their direct prospective to be, even in the present days, advanced architectural and engineering solutions. In the present paper, a form finding for a cement based tessellated pierced vault is studied. The multi-body rope approach (MRA) was used to define compression-only vault optimal shapes. Successively, the thrust network analysis (TNA) was implemented by Rhino-vault for a further validation of the shape and the definition of different tessellation meshes of the surfaces, according to different hole pattern configuration. Different piercing percentage of the vaults were considered and compared for the best solution identification. In addition, the geometrical solutions were analyzed by means of global stability analysis, taking into account the different positions of the holes. Furthermore, 3D printing with a Fuse Deposition Modeling (FDM) technique in polylactide (PLA) material (completely eco-friendly) is used for the construction of the formworks of the cement based blocks (dowels) useful for the assembly of a vault scaled prototype. The prototype of the vault, characterized by a certain piercing percentage was subjected to different loading conditions and monitored by a non-contact device based on the Digital Image Correlation (DIC) technique. The 3D-DIC was performed to recognize the structural behavior during the loading process of the model (prototype). DIC measurements were used to recognize in advance the critical condition of the vault under loading and the displacement measurements were correlated to the different loading phases up to the collapse condition.
19
Qiu, Meikang, Emil Khisamutdinov, Zhengyi Zhao, Cheryl Pan, Jeong-Woo Choi, Neocles B. Leontis e Peixuan Guo. "RNA nanotechnology for computer design and in vivo computation". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, n. 2000 (13 ottobre 2013): 20120310. http://dx.doi.org/10.1098/rsta.2012.0310.
Abstract (sommario):
Molecular-scale computing has been explored since 1989 owing to the foreseeable limitation of Moore's law for silicon-based computation devices. With the potential of massive parallelism, low energy consumption and capability of working in vivo , molecular-scale computing promises a new computational paradigm. Inspired by the concepts from the electronic computer, DNA computing has realized basic Boolean functions and has progressed into multi-layered circuits. Recently, RNA nanotechnology has emerged as an alternative approach. Owing to the newly discovered thermodynamic stability of a special RNA motif (Shu et al. 2011 Nat. Nanotechnol. 6 , 658–667 ( doi:10.1038/nnano.2011.105 )), RNA nanoparticles are emerging as another promising medium for nanodevice and nanomedicine as well as molecular-scale computing. Like DNA, RNA sequences can be designed to form desired secondary structures in a straightforward manner, but RNA is structurally more versatile and more thermodynamically stable owing to its non-canonical base-pairing, tertiary interactions and base-stacking property. A 90-nucleotide RNA can exhibit 4 90 nanostructures, and its loops and tertiary architecture can serve as a mounting dovetail that eliminates the need for external linking dowels. Its enzymatic and fluorogenic activity creates diversity in computational design. Varieties of small RNA can work cooperatively, synergistically or antagonistically to carry out computational logic circuits. The riboswitch and enzymatic ribozyme activities and its special in vivo attributes offer a great potential for in vivo computation. Unique features in transcription, termination, self-assembly, self-processing and acid resistance enable in vivo production of RNA nanoparticles that harbour various regulators for intracellular manipulation. With all these advantages, RNA computation is promising, but it is still in its infancy. Many challenges still exist. Collaborations between RNA nanotechnologists and computer scientists are necessary to advance this nascent technology.
20
Dimitrov, Nikolay, Ezer Castillo, Michael Njuki e Abdullah Faisal Pasha. "Nanoporous Cu-Sn Intermetallic Material for Interconnects in Electronic Packaging". ECS Meeting Abstracts MA2023-02, n. 21 (22 dicembre 2023): 1279. http://dx.doi.org/10.1149/ma2023-02211279mtgabs.
Abstract (sommario):
Nanostructured and nanoparticulate Cu-based materialshave emerged as viable replacements of conventional solder materials for realizing high-performing and reliable interconnection in today's 2.5D/3D electronic packaging. Unlike the traditional interconnects, those materials offer better compliance during the overall packaging routines. Owing to their highly developed surface area resulting of their uniform interconnected porosity, said nanomaterials also enable joint formation by sintering by thermal compression realized at high pressure and at much lower temperatures compared to bulk counterparts. Recently, sintering of nanoporous (np) Cu was demonstrated under high pressure and temperature after initial pre-treatment in acid for surface oxide removal. Separately, other studies have been focused on the attachment of Cu pillars to pads by using nanoparticulate Cu pastes as sintering material. The ultimate goal is to develop materials that facilitate a highly effective and durable chip-to-substrate interconnection. In this report, we discuss the development and use of nanoporous uniform and continuous CuSn films for low-temperature joint formation. The novelty of this work is realized through the introduction of tin (Sn) to work along with the np-Cu structure for ensuring lower sintering temperatures with a goal of producing packaging interconnects based on CuSn intermetallic compound (IMC). The addition of Sn to the np-Cu system is performed using a bottom-up, all-electrochemical synthetic approach (see Figure 1). The method is founded on the initial synthesis of thin films of np-Cu by dealloying of Cu-Zn alloys, followed by a conformal coating with a thin layer of Sn. The main goal of the proposed approach is to form a np-CuSn composite that upon sintering at high temperature and pressure, transitions into a densely compressed Cu3Sn IMC bonding material. Realized accordingly as interconnect layer, said material ensures good stability at high current densities (greater than 1×105 A ⋅ cm2 ) and low electrical resistivity (equal or less than 8.5 µΩ ⋅ cm). The synthetic details and then the applicability of the Cu-Sn nanomaterials obtained using the approach for synthesis of a low-temperature joint formation material are also discussed. The Sn-coating process was administered by galvanic pulse plating, which was optimized to provide a conformal Sn coating and thus, to retain the initial np-Cu overall porous structure. Another optimization effort was made for ensuring a Sn atomic fraction that allows for the formation of Cu6Sn5 IMC. After the optimization process for determining the necessary plating conditions for reaching mostly Cu6Sn5 composition ratio, the material was subjected to sintering at temperatures in the range from 300ºC to 200oC, and at a pressure of 20 MPa. We found that the joints formed were heavily densified and consisted mainly of Cu3Sn IMC. The report presents the new approach as a facile and cost-effective method for synthesizing nanostructured Cu-Sn films as viable candidates for a new-generation of interconnect materials together with the demonstration of assembly processes that optimize robustness and reliability. The discussion also shows the proposed approach’s applicability by realization of low-temperature sintering of nanostructured CuSn films in pre-designed fine pitch assemblies. Figure 1: Schematic representation demonstrating key steps of the approach for synthesis of np-CuSn composites. Figure 1
21
Xu, Bo-Han, Shi-Yuan Jiao, Bi-Lin Wang e Abdelhamid Bouchaïr. "Mechanical Performance of Timber-to-Timber Joints with Densified Wood Dowels". Journal of Structural Engineering 148, n. 4 (aprile 2022). http://dx.doi.org/10.1061/(asce)st.1943-541x.0003317.
22
Xu, Bo-Han, Yi-Ge Zhao, Kong-Bin Yu, Abdelhamid Bouchaïr e Binsheng Zhang. "Pull-Out Performance of Densified Wood Dowels Embedded into Glued Laminated Timber". Journal of Materials in Civil Engineering 35, n. 9 (settembre 2023). http://dx.doi.org/10.1061/jmcee7.mteng-15299.
23
Xu, Bo-Han, Kong-Bin Yu, Shi-Yuan Jiao, Yan-Hua Zhao e Binsheng Zhang. "Pull-Out Performance of Timber Joints with Glued-In Densified Wood Dowels". Journal of Materials in Civil Engineering 35, n. 8 (agosto 2023). http://dx.doi.org/10.1061/jmcee7.mteng-15610.
24
Shabanian, Milad, e Nicole Leo Braxtan. "Thermo-mechanical behavior of CLT beam-to-girder assemblies connected with T-shaped dowelled connections before, during and after fire exposure". Journal of Structural Fire Engineering, 21 dicembre 2022. http://dx.doi.org/10.1108/jsfe-04-2022-0015.
Abstract (sommario):
Purpose3-ply cross-laminated timber (CLT) is used to investigate the thermo-mechanical performance of intermediate-size assemblies comprised of T-shaped welded slotted-in steel doweled connections and CLT beams at ambient temperature (AT), after and during non-standard fire exposure.Design/methodology/approachThe first set of experiments was performed as a benchmark to find the load-carrying capacity of the assembly and investigate the failure modes at AT. The post-fire performance (PFP) test was performed to investigate the residual strength of the assembly after 30-min exposure to a non-standard fire. The fire-performance (FP) test was conducted to investigate the thermo-mechanical behavior of the loaded assembly during non-standard fire exposure. In this case, the assembly was loaded to 67% of AT load-carrying capacity and partially exposed to a non-standard fire for 75 min.FindingsEmbedment failure and plastic deformation of the dowels in the beam were the dominant failure modes at AT. The load-carrying capacity of the assembly was reduced to 45% of the ambient capacity after 30 min of fire exposure. Plastic bending of the dowels was the principal failure mode, with row shear in the mid-layer of the CLT beam and tear-out failure of the header sides also observed. During the FP test, ductile embedment failure of the timber in contact with the dowels was the major failure mode at elevated temperature.Originality/valueThis paper presents for the first time the thermo-mechanical performance of CLT beam-to-girder connections at three different thermal conditions. For this purpose, the outside layers of the CLT beams were aligned horizontally.Highlights Load-carrying capacity and failure modes of CLT beam-to-girder assembly with T-shaped steel doweled connections at ambient temperature presented.Residual strength and failure modes of the assembly after 30-min partially exposure to the non-standard fire provided throughout the post-fire performance test.Fire resistance of the assembly partially exposed to the non-standard fire highlighted.
25
Shabanian, Milad, e Nicole Leo Braxtan. "Thermomechanical behavior of Glulam-beam connected to CLT-wall assemblies with steel doweled connections before, during and after fire". Journal of Structural Fire Engineering, 7 dicembre 2022. http://dx.doi.org/10.1108/jsfe-02-2022-0007.
Abstract (sommario):
PurposeThermomechanical behavior of intermediate-size beam-to-wall assemblies including Glulam-beams connected to cross-laminated timber (CLT) walls with T-shape steel doweled connections was investigated at ambient temperature (AT) and after and during non-standard fire exposure.Design/methodology/approachThree AT tests were conducted to evaluate the load-carrying capacity and failure modes of the assembly at room temperature. Two post-fire performance (PFP) tests were performed to study the impact of 30-min (PFP30) and 60-min (PFP60) partial exposure to a non-standard fire on the residual strength of the assemblies. The assemblies were exposed to fire in a custom-designed frame, then cooled and loaded to failure. A fire performance (FP) test was conducted to study the fire resistance (FR) during non-standard fire exposure by simultaneously applying fire and a mechanical load equal to 65% of the AT load carrying capacity.FindingsAt AT, embedment failure of the dowels followed by splitting failure at the Glulam-beam and tensile failure of the epoxy between the layers of CLT-walls were the dominant failure modes. In both PFP tests, the plastic bending of the dowels was the only observed failure mode. The residual strength of the assembly was reduced 14% after 30 min and 37% after 60 min of fire exposure. During the FP test, embedment failure of timber in contact with the dowels was the only major failure mode, with the maximum rate of displacement at 51 min into the fire exposure.Originality/valueThis is the first time that the thermomechanical performance of such an assembly with a full-contact connection is presented.
26
Huang, Haoyu, e Wen-Shao Chang. "Enhancing resilience in timber connections with SMA dowel and DVW reinforcement". Proceedings of the Institution of Civil Engineers - Engineering History and Heritage, 21 novembre 2023, 1–12. http://dx.doi.org/10.1680/jenhh.23.00009.
Abstract (sommario):
Dowel-type timber connections are commonly found in historic buildings and require reinforcement and repair to ensure their resilience against natural disasters is maintained. This study aims to enhance the resilience of dowel-type connections by equipping them with shape memory alloy (SMA) dowels and densified veneer wood (DVW) reinforcement. The research findings reveal that the performance of SMA bars under cyclic bending is superior to that of steel, in terms of self-centring effect and ductility. Dynamic testing of the SMA-dowelled timber connections shows that connections using SMA exhibit lower residual deformation and better self-centring than those using steel. Additionally, the DVW reinforcement not only improves the self-centring but also the resistance of the SMA-dowelled connection. The comparison between solid bars and tubes shows that the solid bars perform better in terms of damping, resistance, and self-centring. These results demonstrate the potential of developing resilient timber connections and improving the performance of SMA-dowelled timber connections.
27
Shabanian, Milad, e Nicole Leo Braxtan. "Thermo-mechanical behavior of Glulam beam-to-girder assemblies with steel doweled connections before, during and after fire". Journal of Structural Fire Engineering, 20 gennaio 2022. http://dx.doi.org/10.1108/jsfe-04-2021-0018.
Abstract (sommario):
Purpose The purpose of this paper is to investigate the thermo-mechanical behavior of intermediate-size glued-laminated beam-to-girder assemblies connected with T-shaped slotted-in steel doweled connections at ambient temperature (AT), after and during non-standard fire exposure. Design/methodology/approach AT tests were performed using a universal testing machine (UTM) to evaluate the load-carrying capacity and failure modes of the assembly at room temperature. Post-fire-performance (PFP) tests were conducted to study the impact of 30-min and 60-min partial exposure to a non-standard fire on the residual strength of the assemblies. The assemblies were subject to fire in a custom-designed frame, then cooled and loaded to failure in the UTM. A fire-performance test was conducted to investigate the fire-resistance during non-standard fire exposure by simultaneously applying fire and mechanical load with the custom frame. Findings At AT, embedment failure of the dowels followed by brittle splitting failure were found to be the dominant failure modes in the beams. In the PFP tests, embedment failure and plastic bending of the dowels were the only observed failure modes. The residual strength of the assembly was reduced by 23.7% after 30-min and 47.8% after 60-min of fire exposure. Ductile embedment failure of the timber in contact with the dowels was the only failure mode observed during the fire-performance test, with the maximum rate of displacement at 57 min into the fire. Originality/value Data are presented for full-contact (no gap) connections in Glulam assemblies. PFP results are first to be published.
28
Dutta, Pronoy, Sujit Kumar Deb, Amalika Patra, Golam Masud Karim, Abhisek Majumder, Pradip Kumar, Parameswar Krishnan Iyer, Narayanan Padma e Uday Narayan Maiti. "Activating Ion Channels in Collapsed Hydrogel Derived Densified MXene Films with Cellulose Nanofibers to Overcome the Areal Versus Volumetric Capacitance Trade‐Off". Small, 26 aprile 2024. http://dx.doi.org/10.1002/smll.202400119.
Abstract (sommario):
AbstractConcomitant achievement of all three performance pillars of a supercapacitor device, namely gravimetric, areal, and volumetric capacitance is a grand challenge. Nevertheless, its fulfilment is indispensable for commercial usage. Although, high compactness is the fundamental requirement to achieve high volumetric performance, it severely affects ion transportation in thick electrodes. Such trade‐off makes it extremely challenging to realize very high areal and volumetric performance simultaneously. Here, a collapsed hydrogel strategy is introduced to develop MXene/cellulose nanofiber (CNF) based densified electrodes that offer excellent ion transportation despite a massive increase in areal mass loading (>70 mg cm−2). Quasi‐oriented MXene/CNF (MXCF) hydrogels are produced through an electric field‐guided co‐assembly technique. Ambient dehydration of these hydrogels incorporates numerous pores in the resultant compact electrodes due to crumpling of the MXene sheets, while CNF ensures connectivity among the locally blocked pores in different length scales. The resultant collapsed MXCF densified electrode shows a remarkably high areal capacitance of 16 F cm−2 while simultaneously displaying a high volumetric capacitance of 849.8 F cm−3 at an ultrahigh mass loading of up to 73.4 mg cm−2. The universality of strategy, including the co‐assembly of hydrogel and its collapse, is further demonstrated to develop high‐performance asymmetric and wearable devices.
29
S. Rodriguez, Rennier, Maiden Grace R. Maming e Frederick Ray I. Gomez. "Package and Process Design Augmentation of QFN Leadframe Device". Journal of Engineering Research and Reports, 21 gennaio 2020, 1–6. http://dx.doi.org/10.9734/jerr/2019/v9i417026.
Abstract (sommario):
Innovations and breakthroughs either through process, equipment or material is known in semiconductor industries as a positive option in overcoming the existing limitations and assembly handicaps. This presentation discusses the assembly methodology and packaging design of a quad-flat no-leads (QFN) devices using grid design molding tool and leadframe with exposed copper tie bar. Realization of this improved package design proposed the removal of mechanical blade as the primary cutting technique of separating the molded leadframes likewise assembly rejection and defect related to the mechanical blade material together with the processing limitations is mitigated as well. Furthermore, the improved design is realized to be a better alternative for manufacturing tighter clearances and unit-unit pitching requirement thus supports densified and critical package design.
30
Elafify, Mohamed S., Toru Itagaki, Nermeen A. Elkasabgy, Sinar Sayed, Yoshihiro Ito e Motoki Ueda. "Reversible Transformation of Peptide Assembly Between Densified-Polysarcosine-Driven Kinetic and Helix-Orientation-Driven Thermodynamic Stable Morphologies". Biomaterials Science, 2023. http://dx.doi.org/10.1039/d3bm00714f.
Abstract (sommario):
Stimuli-responsive transformable biomaterials development can be manipulated practically by fine-tuning the built-in molecular design of their structural segments. Here, we demonstrate a peptide assembly by the bola-type amphiphilic polypeptide, glycolic...
31
Li, Peng, Ziqiu Wang, Yuxiang Qi, Gangfeng Cai, Yingjie Zhao, Xin Ming, Zizhen Lin et al. "Bidirectionally promoting assembly order for ultrastiff and highly thermally conductive graphene fibres". Nature Communications 15, n. 1 (9 gennaio 2024). http://dx.doi.org/10.1038/s41467-024-44692-7.
Abstract (sommario):
AbstractMacroscopic fibres assembled from two-dimensional (2D) nanosheets are new and impressing type of fibre materials besides those from one-dimensional (1D) polymers, such as graphene fibres. However, the preparation and property-enhancing technologies of these fibres follow those from 1D polymers by improving the orientation along the fibre axis, leading to non-optimized microstructures and low integrated performances. Here, we show a concept of bidirectionally promoting the assembly order, making graphene fibres achieve synergistically improved mechanical and thermal properties. Concentric arrangement of graphene oxide sheets in the cross-section and alignment along fibre axis are realized by multiple shear-flow fields, which bidirectionally promotes the sheet-order of graphene sheets in solid fibres, generates densified and crystalline graphitic structures, and produces graphene fibres with ultrahigh modulus (901 GPa) and thermal conductivity (1660 W m−1 K−1). We believe that the concept would enhance both scientific and technological cognition of the assembly process of 2D nanosheets.
32
Rodriguez, Rennier, e Frederick Ray Gomez. "Semiconductor QFN Package with Advanced Interlocking Design". Journal of Engineering Research and Reports, 6 aprile 2020, 1–6. http://dx.doi.org/10.9734/jerr/2020/v12i117069.
Abstract (sommario):
The mechanical interlocking structure for quad-flat no-lead (QFN) assembly for densified leadframe degrades as the package becomes thinner. Detractors such as package reliability and design requirement hinder further qualification of leadframes with increased number of input/output (I/O) pins. In this paper, a new and advanced design of leadframe is discussed and presented with improvement in mechanical interlocking structure of high stress areas such as lead and pad junction. The leadframe is re-designed having lead lines on the lead and pad that will be etched away after molding process replacing full copper base frame. Through application of the design, the effective mechanical interlocking is improved from 60% to 100% for mold-lead and mold-pad interface.
33
Nishiyama, Norikazu, Shunsuke Tanaka, Yoshiyuki Egashira, Yoshiaki Oku, Akira Kamisawa e Korekazu Ueyama. "Synthesis of Ordered Nanoporous Silica Film With High Structural Stability". MRS Proceedings 716 (2002). http://dx.doi.org/10.1557/proc-716-b5.2.
Abstract (sommario):
AbstractA mesoporous silica film was prepared on a silicon substrate using a spin-coating process followed by a tetraethyl orthosilicate (TEOS) vapor treatment. The stability of a formed silica network before TEOS treatment is thought to be insufficient because the rate of the condensation reaction is not high at temperatures below 453 K. The density of silica wall surrounding surfactant assembly could be low, resulting in the structural contraction with the formation of a silica network. On the other hand, the TEOS-treated mesoporous silica film did not contract during calcination, showing high structural stability. In the TEOS treatment, TEOS molecules penetrate into an originally deposited silicate film and react with silanol groups. The densified silica wall has high structural stability and hardly contracts under a calcination process. A flat mesoporous silica film about 250 nm thick was grown from the silicon substrate. A periodic hexagonal porous structure was observed in the FE-SEM image of the cross section of the TEOS-treated film. This indicates that the channels run predominantly parallel to the surface of the silicon substrate. The developed film is a promising material such as chemical sensors, low-k films and other optoelectronic devices.
34
Taneja, Sorab, Will Tenpas, Mehul Jain, Peter Alfonsi, Abhinav Ratagiri, Ann Saterbak e Jason Theiling. "Simulation device for shoulder reductions: overview of prototyping, testing, and design instructions". Advances in Simulation 8, n. 1 (9 marzo 2023). http://dx.doi.org/10.1186/s41077-023-00246-3.
Abstract (sommario):
Abstract Background Shoulder dislocations are common occurrences, yet there are few simulation devices to train medical personnel on how to reduce these dislocations. Reductions require a familiarity with the shoulder and a nuanced motion against strong muscle tension. The goal of this work is to describe the design of an easily replicated, low-cost simulator for training shoulder reductions. Materials and methods An iterative, stepwise engineering design process was used to design and implement ReducTrain. A needs analysis with clinical experts led to the selection of the traction-countertraction and external rotation methods as educationally relevant techniques to include. A set of design requirements and acceptance criteria was established that considered durability, assembly time, and cost. An iterative prototyping development process was used to meet the acceptance criteria. Testing protocols for each design requirement are also presented. Step-by-step instructions are provided to allow the replication of ReducTrain from easily sourced materials, including plywood, resistance bands, dowels, and various fasteners, as well as a 3D-printed shoulder model, whose printable file is included at a link in the Additional file 1: Appendix. Results A description of the final model is given. The total cost for all materials for one ReducTrain model is under US $200, and it takes about 3 h and 20 min to assemble. Based on repetitive testing, the device should not see any noticeable changes in durability after 1000 uses but may exhibit some changes in resistance band strength after 2000 uses. Discussion The ReducTrain device fills a gap in emergency medicine and orthopedic simulation. Its wide variety of uses points to its utility in several instructional formats. With the rise of makerspaces and public workshops, the construction of the device can be easily completed. While the device has some limitations, its robust design allows for simple upkeep and a customizable training experience. Conclusion A simplified anatomical design allows for the ReducTrain model to serve as a viable training device for shoulder reductions.