Plate Assembly Research Articles

SH3Ps-Evolution and Diversity of a Family of Proteins Engaged in Plant Cytokinesis.

SH3P2 (At4g34660), an Arabidopsis thaliana SH3 and Bin/amphiphysin/Rvs (BAR) domain-containing protein, was reported to have a specific role in cell plate assembly, unlike its paralogs SH3P1 (At1g31440) and SH3P3 (At4g18060). SH3P family members were also predicted to interact with formins—evolutionarily conserved actin nucleators that participate in microtubule organization and in membrane–cytoskeleton interactions. To trace the origin of functional specialization of plant SH3Ps, we performed phylogenetic analysis of SH3P sequences from selected plant lineages. SH3Ps are present in charophytes, liverworts, mosses, lycophytes, gymnosperms, and angiosperms, but not in volvocal algae, suggesting association of these proteins with phragmoplast-, but not phycoplast-based cell division. Separation of three SH3P clades, represented by SH3P1, SH3P2, and SH3P3 of A. thaliana, appears to be a seed plant synapomorphy. In the yeast two hybrid system, Arabidopsis SH3P3, but not SH3P2, binds the FH1 and FH2 domains of the formin FH5 (At5g54650), known to participate in cytokinesis, while an opposite binding specificity was found for the dynamin homolog DRP1A (At5g42080), confirming earlier findings. This suggests that the cytokinetic role of SH3P2 is not due to its interaction with FH5. Possible determinants of interaction specificity of SH3P2 and SH3P3 were identified bioinformatically.

Inexpensive Computations Using Computational Fluid Dynamics Combined With Asymptotics Applied to Laminar Mixed Convection in a Vertical Channel

Abstract In this work, a solution technique is proposed by synergistically combining asymptotics and computational fluid dynamics to ascertain a problem of laminar mixed convection heat transfer in a vertical channel. First, numerical simulation is carried out on a vertical channel that consists of an aluminum heater plate assembly at the center of the channel. The numerical model is treated as a conjugate heat transfer problem, and the concept of perturbation and blending is incorporated wherein the limiting solution of natural and forced convection is obtained in terms of average Nusselt number. These correlations are then blended to find a unified composite correlation that work very well for extreme limits of mixed convection. The Richardson number is chosen as an independent variable in the present analysis; as a result, the Nusselt number correlation is cogent for the mixed convection region. Upon performing the numerical simulations, the results of the mixed convection are then compared with experimental results available in the literature for the purpose of validation of the numerical solution. The results of the present work emphasize that, with minimum computational fluid dynamics (CFD) solutions, one can obtain a reasonably good composite correlation for the Nusselt number for mixed convection and also a substantial reduction of computations is possible ensuing an asymptotically flawless solution.

Analysis on Synchronizing and Gear Shifting Force of Commercial Vehicle Powertrain

Based on a commercial vehicle transmission as the research object, the paper analyses the influence for commercial vehicle powertrain synchronization and shift performance by the rotational inertia of the clutch driven plate assembly and transmission input speed. According to the synchronization and shifting mechanism of the transmission, transmission shift dynamics model was established. Analyzing the causes of shift impact and the critical shifting force for mis-engagement put forward the shift control strategy to avoid shift impact. We can draw a conclusion that optimizing the clutch driven plate inertia parameter during clutch design can effectively improve the shift performance of the transmission.

Foldable cones as a framework for nonrigid origami.

The study of origami-based mechanical metamaterials usually focuses on the kinematics of deployable structures made of an assembly of rigid flat plates connected by hinges. When the elastic response of each panel is taken into account, novel behaviors take place, as in the case of foldable cones (f-cones): circular sheets decorated by radial creases around which they can fold. These structures exhibit bistability, in the sense that they can snap through from one metastable configuration to another. In this work, we study the elastic behavior of isometric f-cones for any deflection and crease mechanics, which introduce nonlinear corrections to a linear model studied previously. Furthermore, we test the inextensibility hypothesis by means of a continuous numerical model that includes both the extended nature of the creases, stretching and bending deformations of the panels. The results show that this phase-field-like model could become an efficient numerical tool for the study of realistic origami structures.

Design and construction of a snowfall protection structure on the Baku-Tbilisi-Kars rail corridor, Georgia

This project involved the design and construction of a structure comprising four tunnels with a total length of 2434m. An initial in situ concrete scheme was changed to a corrugated steel plate assembly, enabling improvements in material transportation and construction.

A ∼100 μm-resolution position-sensitive detector for slow positronium

In this work we describe a high-resolution position-sensitive detector for positronium. The detection scheme is based on the photoionization of positronium in a magnetic field and the imaging of the freed positrons with a Microchannel Plate assembly. A spatial resolution of (88±5) μm on the position of the ionized positronium –in the plane perpendicular to a 1.0 T magnetic field– is obtained. The possibility to apply the detection scheme for monitoring the emission into vacuum of positronium from positron/positronium converters, imaging positronium excited to a selected state and characterizing its spatial distribution is discussed. Ways to further improve the spatial resolution of the method are presented.

Research on Base Welding Technology of Alkaline Welding Rod with Arc Method

The single-sided welding double-sided forming technology of electrode arc welding is the operation technology that must be mastered in the qualification of welders. The welding of the bottom layer is the key. In this paper, the influence of factors such as plate assembly size, process parameters and operation mode on welding quality is analyzed by welding test method, and the best welding process and operation technology are determined, which provides guarantee for welding training.

Full-scale numerical study on the flow characteristics and mal-distribution phenomena in SG steam-water separation system of an advanced PWR

The steam-water separation system is of great importance to ensuring the steam quality in a PWR UTSG. In the present work, the full-scale three-dimensional CFD analysis is performed to study the mal-distribution steam flow in the system using ANSYS-FLUENT platform. A full-scale model of newly-designed PWR is established and all the sophisticated structures of 19 swirl-vane separators are modeled. Besides, the porous medium model is adopted to simplify the steam flow inside the dryers because of the complex structure of wave-type vanes. Employing CFD methodologies, detailed flow characteristics in the whole system are captured, especially the velocity fields of steam at inlets of 7 dryer units. The outcomes show that the maximum unit-area mass-flow rate appears at the entrance of #4 dryer which is in the central part of dryers. In addition, the maximum entry velocity is 2.136 m/s, while the velocity is decreased to 1.049 m/s, lower than the critical velocity, with the application of an orifice plate assembly with the perforation in different calibers on the plate. Also, the effect of the separator down-comer on the mal-distribution phenomenon is also analyzed. In general, the current work could be expected to be a basis for the future optimization on moisture separation components in the steam generator.

Experimental study of vibration isolation in thin-walled structural assemblies with embedded total-internal-reflection metasurfaces

The concept of total-internal-reflection elastic metasurface (TIR-MS) was recently proposed [1] and employed within flexible planar waveguides in order to create highly subwavelength sound-hard barriers impenetrable to low frequency elastic waves. The underlying physical mechanism relies on the design of engineered interfaces exhibiting extreme phase gradients such that any incoming wave at, approximately, any incidence will experience total-internal-reflection conditions. At the design frequency, the metasurface exhibits a large phase gradient such that, in accordance with the generalized Snell's law, the first critical angle is virtually always exceeded. It is worth noting that in practical realizations, the actual total reflection performance might vary depending on the angle of incidence. This dependence is due to the discrete implementation of the metasurface which results in diffraction effects. This paper presents the results of an experimental study that explores the vibration isolation performance of TIR-MS when applied to structures made of complex combinations of different elastic waveguides (e.g. bolted assemblies of beams, plates, and shells). Such system can be seen as a prototypical structure emulating mechanical assemblies of practical interest for many engineering applications. Experimental results confirm that, when the TIR-MS is embedded in the host waveguide, significant vibration isolation capabilities are achieved under quasi-omnidirectional incidence and highly subwavelength excitation conditions (i.e. the ratio of the operating wavelength to the width of the TIR-MS is approximately 5.25). These experimental results suggest new interesting directions to achieve vibration isolation and mechanical energy filtering for practical engineering systems.

Lung-Inspired PEM Fuel Cells Built from Layered Printed Circuit Boards

Homogenous, scalable, and uniform distribution of reactants at membrane-electrode assembly (MEA) level are critical to the performance of polymer electrolyte membrane (PEM) fuel cells. To achieve this, cathode flow fields were introduced that have fractal flow geometry, inspired by the air flow mechanism in lungs [1]. These were manufactured using direct metal laser sintering. Here, we discuss the design and characterisation of lung-inspired fuel cell flow plates using cheap and light printed circuit boards (PCBs) manufactured using computer numeric control (CNC) machining. X-Ray computed tomography (CT) scans of the developed fractal flow fields demonstrate a uniform and well aligned PCB plate assembly that results in a fractal hierarchy of flow channels, as shown in figure (1a) and (1b). Polarization performance at 70% reactant humidity and 45oC cell temperature for the fractal flow field was 12% higher than the performance of a single-serpentine, at 0.6V individual cell potential, as shown in figure (2).The cell temperature profile for the fractal flow field was more stable and uniform, compared to a rapid rise in profile of the single-serpentine one. The voltage decay measurements, at constant current density hold, indicate that voltages of fractal and single-serpentine flow fields vary within 2% and 6% of their initial voltage values, respectively, over a period of 6h continuous operation. Furthermore, Electrochemical Impedance Spectroscopic (EIS) measurements establish higher ohmic and mass transport resistances for the single-serpentine compared to the fractal flow field, at current densities ranging between 100mA/cm2 and 900mA/cm2. Keywords: Fractal, X-Ray CT, EIS,CNC, PCB, lung-inspired, hierarchical Reference: [1] P. Trogadas, J.I.S. Cho, T.P. Neville, J. Marquis, B. Wu, D.J.L. Brett and M.-O. Coppens, 2018, A lung-inspired approach to scalable and robust fuel cell design. Energy & Env. Sci. 11, 136-143. Figure 1

An integrated model of the water transport in nonuniform compressed gas diffusion layers for PEMFC

Abstract Water transport in gas diffusion layer (GDL) is a very important issue for high power density Proton Exchange Membrane Fuel Cell (PEMFC). During the GDL and bipolar plate (BPP) assembly process, the water transport behavior is greatly influenced by the nonuniform compression on the GDL, which leads to uneven distribution of the internal mass transport pores. In this study, an integrated model is developed to predict the water transport in nonuniform compressed GDL. Firstly, a GDL compression deformation model is built to obtain the relationship between the GDL deformation and assembly clamping force based on energy method. Then, a water transport model is established by considering the probability density function (PDF) of the pore size for the compressed GDL. The accuracy of the integrated model has been verified by comparing with the finite element method (FEM) and the computational fluid dynamics (CFD) simulation results. The influence of assembly clamping force, GDL thickness and channel geometry are analyzed based on the integrated model. Drainage pressure increases monotonically with the assembly clamping force and is divided into three stages. For the baseline case, 0.2 mm of GDL thickness and small rib-channel ratio is conducive to improving drainage capacity. It provides the guidance for matching of GDL/BPP assembly condition and performance prediction of PEMFC.

Functional and Radiological Outcome of Unstable Intertrochanteric Fracture Post Dynamic Hip Screw Fixation

IntroductionIntertrochanteric fractures are the most frequently operated fracture type and have the highest postoperative fatality rate. The most commonly used devices are the dynamic hip screw (DHS) with side plate assemblies and proximal femoral nail (PFN). The aim of this study was to determine the functional and radiological outcome of unstable intertrochanteric fracture post DHS fixation at a tertiary care hospital in Karachi, Pakistan.MethodsA study was carried out in the department of orthopedics at the Jinnah Postgraduate Medical Center (JPMC), from 12th June 2016 to 8th September 2017. A total of 106 patients between 18 and 75 years of age with unstable intertrochanteric fracture were included. Those patients who had multiple injuries and open fractures, subtrochanteric fractures, intracapsular fractures neck of femur, pathological fractures and patients who were non-ambulatory prior to their injury were excluded. Functional outcomes were measured both during pain using the visual analog scale and range of motion on goniometer between 80 and 100 degrees. Satisfactory outcomes were measured after three months.ResultsA total of 106 patients with the radiological diagnosis of the unstable intertrochanteric fracture having post DHS fixation were included in this study. Out of which, 69.8% (74) were males and the mean age was 66.61 ± 7.79 years over the range of 50 to 80 years. Patients with type II diabetes were 22.6% (24) with a mean duration of 4.3 ± 8.37 years. At the end of three months, no pain was reported in 82.1% (87) patients and 85.8% (91) patients had normal function. The satisfactory radiological outcome was observed in 86.8% (92) patients. Overall, acceptable outcomes were observed in 81.1% (86) patients at the end of three months.ConclusionThe treatment of unstable intertrochanteric fracture with dynamic hip screw (DHS) fixation results in better outcomes. In our study, we observed acceptable outcomes in a vast majority, 81.1%, of patients after three months of DHS fixation of the unstable intertrochanteric fracture.

Fluorescence intensity monitors as intensity and beam-position diagnostics for X-ray free-electron lasers.

For LCLS-II, a fluorescence intensity monitor for the non-invasive, pulse-by-pulse normalization of experiments has been developed. A prototype diagnostic was constructed with a microchannel plate assembly and two photodiodes. The diagnostic was then installed in the LCLS SXR instrument Kirkpatrick-Baez mirror chamber with the detectors located above the vertically reflecting mirror. The linearity, noise and position sensitivity of the detectors have been characterized. The photodiode responsivity is suitable for high pulse energies. The microchannel plate detector shows sufficient responsivity over a wide range of pulse energies. The relative signal from the two photodiodes provides a sensitive measure of the X-ray beam position. The fluorescence intensity monitor provides intensity normalization while being compatible with high incident power, a 0.93 MHz repetition rate and ultra-high vacuum.

Effects of multi-stage rifting and metasomatism on HSE-187Os/188Os systematics of the cratonic mantle beneath SW Greenland

We report highly siderophile element (HSE) abundances and Re–Os isotope compositions, obtained by isotope dilution inductively coupled plasma mass spectrometry, of olivine separates from a suite of multiply metasomatised peridotite xenoliths entrained in kimberlites from SW Greenland. Combined with petrographic and compositional observations on accessory base metal sulphides (BMS), the results reveal new insights into the chemical, physical and mineralogical effects of multi-stage rifting and associated melt percolation on the Archaean lithospheric mantle. Refertilised lherzolites are dominated by rare to frequent small (tens of µm) BMS inclusions in olivine, whereas modally metasomatised phlogopite-bearing lherzolite and wehrlites have higher proportions of more Ni-rich BMS, including abundant large interstitial grains (hundreds of µm). The olivine separates display depleted HSE systematics with Primitive Upper Mantle (PUM)-normalised Pd/Ir of 0.014–0.62, and have both depleted and enriched 187Os/188Os (0.1139–0.2724) relative to chondrite that are not correlated with 187Re/188Os. Four out of ten olivine separates retain similarly depleted Os corresponding to Re-depletion model ages of 2.1–1.8 Ga. They may reflect Palaeoproterozoic refertilisation (lherzolitisation) during Laurentia plate assembly, with re-introduction of clinopyroxene and Os-rich BMS into the originally refractory mantle lithosphere by asthenosphere-derived basaltic melts, followed by recrystallisation and occlusion in olivine. Unradiogenic Os is observed regardless of lithology, including from peridotites that contain abundant interstitial BMS. This reflects addition of Os-poor BMS (<< 1 ppm) during more recent wehrlitisation and phlogopite-introduction, and control of the Os isotopic signature by older Os-rich BMS that precipitated from the basaltic melt. Depletions in compatible HSE (< 0.5 × PUM for Ru, Ir, Os) in all but one olivine separate reflect nugget effects (amount of depleted vs. metasomatic BMS inclusions) and/or loss due to sulphide dissolution into oxidising small-volume melts that invaded the lithosphere during recurrent rifting, the latter supported by similar depletions in published bulk peridotite data. Combined, these multiple metasomatic events destroyed all vestiges of Mesoarchaean or older inheritance in the olivine separates investigated here, and highlight that caution is needed when interpreting Proterozoic Os model ages in terms of Proterozoic lithosphere stabilisation.

A generalized superposition method for accurate free vibration analysis of rectangular plates and assemblies.

A generalized superposition method is presented in this paper for free bending vibration analysis of single rectangular plates and assemblies of rectangular plates with arbitrary boundary conditions. The method was developed on the basis of the Levy method, the principle of superposition, and the uniform convergence of half-range Fourier cosine series for continuous functions in a closed interval. Numerical results, obtained using the proposed method for thin isotropic plates and plate assemblies, show that the proposed method is accurate and rapidly convergent. The proposed method can be extended to handle vibration of moderately thick plates made of isotropic and orthotropic materials.

Cyclic virtual test on wood furniture by Monte Carlo simulation: from compression behavior to connection modeling

Prediction of durability of wood product is a major challenge and an important goal for furniture industry. Numerical simulation based on approximation methods such as the finite element method (FEM) is an efficient and powerful tool to address this challenge while avoiding expensive experimental testing campaigns. Nevertheless, the strong heterogeneity of wood-based materials, the specific geometrical characteristics of wood-based structures (such as furniture that can often be represented as an assembly of beams, plates and/or shells) and the complex nonlinear 3D local behavior near the connections between structural parts may induce some difficulties in the numerical modeling and virtual testing of furniture for robust design purposes. Especially, when cyclic loading occurs, the behavior of junctions in furniture involves a local permanent strain that increases with the number of cycles and that can lead to an important gap potentially affecting the structural integrity of furniture. In this paper, we present an experimental campaign of cyclic compression tests carried out on spruce specimens. Theses specimens are cut out from a bunk bed and loaded under cyclic compression. The cyclic compression loading applied to the specimens leads to an evolution of the permanent strain during cycles that is modeled using a simple law describing the displacement gap as a function of the number of cycles. Considering the strong dispersion in the mechanical properties of wood-based materials and the variabilities induced by the experimental configuration, a stochastic modeling of the gap is proposed by having recourse to the maximum entropy (MaxEnt) principle in order to take into account the random uncertainties on the experimental setup and between the test specimens. The random mechanical response of a complex corner junction in a bunk bed under cyclic loading is then numerically simulated by using a Monte Carlo numerical simulation method as stochastic solver. This provides independent realizations of the random gap evolution (with respect to the number of cycles) in the bunk bed corner, allowing probabilistic quantities of interest related to the random gap, such as first- and second-order statistical moments (mean value, standard deviation) as well as confidence regions (with a given probability level), to be estimated.

Track plates detect the endangered New Mexico jumping mouse

ABSTRACTThe New Mexico jumping mouse (Zapus luteus luteus, formerly Z. hudsonius luteus), an endangered subspecies found in the southwestern United States, inhabits riparian areas with tall, dense herbaceous vegetation as habitat. To detect presence of this species for use in defining life history and habitat use, we developed and tested 4 noninvasive track‐plate methods, and selected the best for field use. New Mexico jumping mice have unique feet and toes that are readily distinguishable from other small mammals within their geographic range. We created reference photos of rodent tracks that confirmed the unique footprints of the jumping mouse and tested this method against detection with live traps in the Apache–Sitgreaves, Arizona, and Santa Fe, New Mexico, USA, National Forests, 2016 and 2017. When comparing the 2 detection methods, in only 1 of 16 comparisons did results differ, where we captured jumping mice in live traps, but did not detect them with track plates. Based on our success with this approach, we developed a 14‐minute instructional video (https://www.youtube.com/watch?v=i2x0Ydc1XVM) on assembly, deployment, and interpretation of track plates. Although trapping provided specific information about individuals, the noninvasive nature of our track‐plate design minimized risk of injury or mortality to animals and lowered study costs. © 2018 The Wildlife Society.

New fatty dihydropyridines present cardioprotective potential in H9c2 cardioblasts submitted to simulated ischemia and reperfusion

Nifedipine is a calcium channel blocker dihydropyridine that has been used in the treatment of hypertension. The production of reactive species and calcium overload are the main contributors to myocardial ischemia-reperfusion (I / R) injury. We investigated the ability of novel dihydropyridines (DHPs) to improve the effect of protecting against the injury induced by ischemia and reperfusion in cardioblasts when compared to nifedipine. Forty three DHPs were created varying the fatty chains derived from palmitic acid, stearic acid and oleic acids and aromatic moiety in addition to the addition of chemical elements such as chlorine, nitrogen dioxide, furfural, hydroxyl and methoxy. Cytotoxicity and inhibition of linoleic oxidation were evaluated for all new DHPs and also for nifedipine. The alpha-tocopherol and butylated hydroxytoluene (BHT) were used as antioxidants controls. The compounds with the best antioxidant potential were used in the ischemia and reperfusion (I / R) induction test in cardioblasts (H9c2). Cardioblasts were treated 24 h after assembly of plates and submitted to the ischemia simulation (30 min), after which, normoxia and cellular nutrition conditions were reestablished, simulating reperfusion (additional 30 min). Right after, cell viability, apoptosis, necrosis, and the generation of reactive oxygen species (ROS) were evaluated. Cell viability during I / R was not altered in cells treated with nifedipine, BHT and the new DHP composed of palmitic acid with hydroxyl group in the aromatic substituent. The other new DHPs increased cell viability during I / R simulation and reduced levels of reactive species compared to the I / R group, demonstrating the antioxidant capacity of the new DHPs. Therefore, DHPS with palmitic and oleic acids in the C3 and C5 position with NO2 or Cl in aromatic moiety, presented the highest antioxidant potential (linoleic oxidant test). The new DHPs increased cell viability during I / R simulation and reduced levels of reactive species compared to the ischemia and reperfusion group, demonstrating the antioxidant capacity of the new DHPs. Taken together, these results indicate that those new DHPs have a greater cardioprotective antioxidant capacity to face the damages of ischemia and reperfusion.

Design, manufacturing and installation of the JT-60SA vacuum vessel gravity support

In the operation of JT-60SA tokamak device, such loads as electromagnetic (horizontal and vertical loads of 2.5 MN and 7.5 MN, respectively) and seismic are imposed on the VV, and thermal expansion takes place during the baking of Vacuum Vessel (VV). The nine Vacuum Vessel Gravity Supports (GSs) have to support the loads and total dead weight of 400 tons including in-vessel components and compensate thermal deformation. Assembling to realize precise positioning of each GS to the VV is indispensable in the limited space between toroidal field coils. To meet the design requirements described above, a GS is equipped with an assembly of flexible plates (FPs) in its lower part and a stem in its upper part with external thread that is screwed upward on the internal thread of VV stub for installation. Electric discharge machining is applied to form FPs without welding. Narrow gap TIG and electron beam welding are also adopted to suppress welding distortion. By the FEM analysis-based design and successful product manufacturing, we have established a design concept and manufacturing technology of GS that has both stiffness and flexibility. The installation mock-up test of GS has also successfully finished.

Jet breaker plate for suppressing gas entrainment and flow induced vibration of a CSRDM shroud tube assembly inside the control plug shell

Abstract The present study proposes a jet-breaker plate (JBP) assembly near the outlet of the porous shroud tube for suppressing the gas entrainment inside the liquid pool and flow induced vibration of the control plug structure. Several JBP designs have been tested. Accelerometers mounted at different locations of the model are used for measurement of flow induced vibration. Flow visualization techniques, i.e. white light visualization, dye visualization, Shadowgraph imaging have been used to characterize the flow behavior near the JBP assembly. Image processing techniques have been employed to quantify turbulence intensity and free-surface fluctuation characteristics near the JBP. The implementation of JBP leads to reduced free-surface fluctuations, lower turbulence intensity near the free surface (by about 50%), significant reduction in hump size (about 95%), elimination of gas entrainment, and mitigation of flow-induced vibration (about 90%).