A new polyurethane-steel honeycomb composite pier anti-collision device: Concept and compressive behavior

A new type of pier anti-collision composite structure composed of honeycomb steel and polyurethane (PU) elastomer was proposed in this study. The impacts of the shape and filling materials of inner core cells on the failure mode, load–displacement cure, bearing capacity, structural stability, and energy absorption were studied by conducting uniaxial compression tests on device segments. Test results showed that the bearing capacity, structural stability, and energy absorption of honeycomb steel structure were significantly improved by PU elastomer filling. Besides, when compared with the square honeycomb structure and the regular hexagon honeycomb structure, the maximum values of average load, total energy absorption (TEA), and specific energy absorption (SEA), which were 69.6 kN, 1986.1 J, and 1300 J/kg, respectively, for the regular triangle honeycomb structure without PU filling, increased to 459.3%, 376.38%, and 212.5%, respectively, for the regular hexagonal core cell structure with PU filling, which was proved to be the most suitable core structure for pier anti-collision device.

Research on the mathematical model construction of art and ideology in visual communication design teaching

Aims To enhance the teaching quality in the field of visual communication design and make students to improve in all aspects of moral, intellectual and physical development, strengthen their ideological education, improve their ideological quality and strengthen their understanding of visual communication design art. Methods By using mathematical methods to construct models, and making appropriate selection of the literature method, practical teaching method and investigation method, the author made a comprehensive study on the artistic problems in art teaching from the aspects of definition, function, characteristics and students’ ideological quality, and discusses potential solutions. Results It had a positive effect on teachers and on their teaching methods, so that they have a better understanding of their teaching work, to motivate themselves towards their goals, make the classroom teaching vivid and improve the teaching efficiency. Conclusion The art of teaching visual communication has a close relationship with the strength and quality of people's thoughts; so, we must strengthen the artistic quality of visual communication design education, to improve students’ ideological quality and the art of teaching visual communication design. In our model, the motivation of teachers to create and sustain interest in students studying visual communication design is stronger when the imagination of ideological content is broad, and when the artistry is positive for right triangle and thoughtful for backward right triangle. The construction of the model is like a regular triangle and an inverted triangle combined to form a regular rectangle mathematical model. It will make visual communication design teaching like Mona Lisa so that people linger.

Imbibition of Newtonian Fluids in Paper-like Materials with the Infinitesimal Control Volume Method

Paper-based microfluidic devices are widely used in point-of-care testing applications. Imbibition study of paper porous media is important for fluid controlling, and then significant to the applications of paper-based microfluidic devices. Here we propose an analytical approach based on the infinitesimal control volume method to study the imbibition of Newtonian fluids in commonly used paper-like materials. Three common paper shapes (rectangular paper strips, fan-shaped and circular paper sheets) are investigated with three modeling methods (corresponding to equivalent tiny pores with circle, square and regular triangle cross section respectively). A model is derived for liquid imbibition in rectangular paper strips, and the control equations for liquid imbibition in fan-shaped and circular paper sheets are also derived. The model is verified by imbibition experiments done using the mixed cellulose ester filter paper and pure water. The relation of imbibition distance and time is similar to that of the Lucas−Washburn (L−W) model. In addition, a new porosity measurement method based on the imbibition in circular paper sheets is proposed and verified. Finally, the flow rates are investigated. This study can provide guidance for the design of different shapes of paper, and for better applications of paper-based microfluidic devices.

Characterization of High Quality, Large-Scale Growth of Monolayer WS2 Domains via Chemical Vapor Deposition Technique

WS2 flakes have been grown successfully on SiO2 substrate via chemical vapor (CVD) deposition method by reduction and sulfurization of WO3 using Ar/ H2 gas and sulfur evaporated from solid sulfur powder. The prepared samples were characterized by optical microscopy (OM), atomic force microscopy (AFM), scanning electron microscopy (SEM), Raman spectra and photoluminescence (PL). Large domain WS2 monolayers are obtained by extending the growth time. The perfect triangular single-crystalline WS2 flakes with an average length of more than 35 µm were achieved. The sharp PL peak (∼1.98 eV) and two distinct Raman peaks (E2g and A1g) with a ∼ 71.5 cm-1 peak split indicating that relatively high quality WS2 crystals with a regular triangle shape can be synthesized. Higher growth time shows larger triangular-shaped of WS2.

New option of tibial plateau plasty in total knee arthroplasty

Introduction There are several options of fixation and plasty for tibial defects. Screw and cement augmentation of the tibia is an alternative to conventional bone autograft and allograft. Although use of metal and cement augments provides reliable support for the tibial plateau and facilitates early weight-bearing on the operated limb the technique fails to maintain enough bone stock for future revisions. The purpose was to present an option of cement and metal augmentation of the tibial component in total knee arthroplasty (TKA). Material and methods The technique consists of cement and screw augmentation using three screws placed vertically as a regular triangle and being perpendicular to the tibial plateau. We describe the technique and a clinical instance of type 2A defect of the proximal tibia using the author's method. Outcome measures were goniometry and radiography. Results Goniometry examination showed positive dynamics in the first week after surgery with flexion of 110.0 degrees, extension 175.0 degrees; at 12 months with flexion of 90.0 degrees and extension of 180.0 degrees. Radiographic examination demonstrated no instability and micromobility of the cement mantle. Discussion The author's technique of screw and cement augmentation of the tibial component was practical for type 2A defects of the proximal tibia with a shortage of materials of bone autografts. This is a pilot study that requires further investigations.

A Surface Energy Approach to Developing an Analytical Model for the Underfill Flow Process in Flip-Chip Packaging

This paper presents a new approach to formulating an analytical model for the underfill process in flip-chip packaging to predict the flow front and the filling time. The new approach is based on the concept of surface energy along with the energy conservation principle. This approach avoids the need of modeling the flow path to predict the flow front and the filling time and thus it is suitable to different configurations of solder bumps, including different shapes and arrangements of solder bumps in flip-chip packaging. An experiment along with the CFD simulation was performed based on a proprietarily developed testbed to verify the effectiveness of this approach. Both the experimental and simulation results show that the proposed approach along with its model is accurate for flip-chip packages with different configurations besides the configuration of a regular triangle arrangement of solder bumps and a spherical shape of the solder bump.

New Syntheses, Analytic Spin Hamiltonians, Structural and Computational Characterization for a Series of Tri-, Hexa- and Hepta-Nuclear Copper (II) Complexes with Prototypic Patterns

We present a series of pyrazolato-bridged copper complexes with interesting structures that can be considered prototypic patterns for tri-, hexa- and hepta- nuclear systems. The trinuclear shows an almost regular triangle with a μ3-OH central group. The hexanuclear has identical monomer units, the Cu6 system forming a regular hexagon. The heptanuclear can be described as two trinuclear moieties sandwiching a central copper ion via carboxylate bridges. In the heptanuclear system, the pyrazolate bridges are consolidating the triangular faces, which are sketching an elongated trigonal antiprism. The magnetic properties of these systems, dominated by the strong antiferromagnetism along the pyrazolate bridges, were described transparently, outlining the energy levels formulas in terms of Heisenberg exchange parameters J, within the specific topologies. We succeeded in finding a simple Kambe-type resolution of the Heisenberg spin Hamiltonian for the rather complex case of the heptanuclear. In a similar manner, the weak intermolecular coupling of two trimer units (aside from the strong exchange inside triangles) was resolved by closed energy formulas. The hexanuclear can be legitimately proposed as a case of coordination-based aromaticity, since the phenomenology of the six-spins problem resembles the bonding in benzene. The Broken-Symmetry Density Functional Theory (BS-DFT) calculations are non-trivial results, being intrinsically difficult at high nuclearities.

The glacier seismo-acoustic monitoring system in the Ukrainian Antarctic Station region

<p>Continuous long-term monitoring of the glacier is not an easy task. For the Woozle Hill ice cap near the Vernadsky Research Station, which is located on Galindez Island (Argentine Islands Archipelago), the task was solved by periodic ice sampling, GNSS measurements, photometry, and the use of GPR in the summer season. Some meteorological parameters were also periodically measured inside the ice cave in the glacier when conditions were favorable. In the past few years, GPR measurements have become more constant, and now they are carried out monthly. For continuous monitoring of the internal stresses of the glacier, we proposed using a network of seismoacoustic mini-arrays located along the perimeter of the glacier. Each array consists of four seismoacoustic sensors arranged in a cross. The length of the line between the extreme sensors reaches 100 meters. Proprietary sensors use an optical system for recording the seismic and infrasonic vibrations. The built-in microcontroller of each sensor transmits the digitized data (16 bit, 100(300) Hz) to the main unit based on the LattePanda, where preprocessing is performed. GPS receiver is also connected here for data synchronization. There is a Wi-Fi module for transmitting data to the collection station. Also, data can be transmitted to the collection station by wires installed on the cable-growth. Power is supplied 220 V through an adapter and a 12V battery. The sensors are waterproof, the rest of the equipment is assembled in a sealed waterproof box. There are three such arrays, in their turn, they form a regular triangle with a side of 700 meters, inside which there is a glacier. The processing consists of detecting signals in each array by the STA / LTA method, followed by correlation processing of the selected data fragment and calculating the azimuth to the signal, wave velocity, period, and amplitude. Also, the isolation of the coherent part of the low-intensity signal at the noise level can be carried out without preliminary STA / LTA detection, using algorithm F-statistics. Correlated interference is clipped in azimuth. The intersection of two or three azimuths allows you to locate the signal source. All parameters of detections with time stamps are recorded in the database and can be further processed using station meteorological data. The system began to be deployed around the glacier in January 2021. The presentation will present the first results of the deployed monitoring system.</p>

Cushioning energy absorption of paper corrugation tubes with regular polygonal cross-section under axial static compression

The paper corrugation tube is an innovative kind of energy absorbing structure and shock absorber which can play an important role on the cushioning energy absorption for airdrop equipments and transportation packaging. The deformation characteristics and failure modes of the regular triangle, quadrangle, pentagon and hexagon paper corrugation tubes were comparatively studied by a series of axial static compression experiments, the cushioning energy absorption was evaluated by the seven characteristic parameters (e.g. initial peak force, mean crush force, total energy absorption, specific energy absorption, crush force efficiency, unit area energy absorption and stroke efficiency), and the influences of tube direction, cross-sectional shape, tube length and compression rate on failure modes and cushioning energy absorption were analyzed and compared. These researches showed that the tubes along X direction only have the accordion deformation mode, yet the tubes along Y direction have four deformation modes including steady state progressive buckling, Euler buckling, angular tear and transverse shear. For the paper corrugation tubes along Y direction, the cross-sectional shape has obvious influence on the cushioning energy absorption of structures, and the specific energy absorption and unit area energy absorption of regular triangle and pentagon tubes are better than those of the tubes with regular quadrilateral and hexagonal cross-section at compression rates of 12 and 48mm/min. The tube length of 150 mm or compression rate of 72 mm/min would cause the increase of contribution proportion of non-ideal deformation mode and the decrease of cushioning properties. The paper corrugation tubes along X direction have more stable and controllable deformation mode, yet the paper corrugation tubes along Y direction have better cushioning energy absorption.