Extra Coarse Research Articles

Modern software capabilities for shape optimization of shells

The article is devoted to the shape optimization of shell structures in Comsol Multiphysics using three gradient-based methods: IPOPT (Interior Point OPTimizer), SNOPT (Sparse Nonlinear OPTimizer) and MMA or GCMMA (the Method of Moving Asymptotes). Two types of complex shapes, such as right helicoid and developable helicoid are taken for the computational experiment. The task is to investigate the initial design and optimization process of two helicoids. To obtain a more accurate result and an interesting design solution, the calculation is carried out using three physics-controlled mesh sizes: extra coarse, fine and extra fine with varying values of special optimization settings, such as maximum displacement (dmax) and filter radius (Rmin). The results obtained using the three methods allow to conclude that the mesh element size and studied parameters dmax and Rmin have a significant impact on the final optimization result.

Peat Substrates Amended with Wood-based Biochar Do Not Influence the Efficacy of Paclobutrazol Drenches

Various soilless substrate components have been evaluated for many years to identify sustainable resources that do not negatively impact plant growth. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. In addition, the use of carbon adsorption for compound removal is widely used in groundwater remediation, municipal water filtration, and volatile organic compounds. Experiment one aimed to determine the impact of coarse biochar (<6 mm) on paclobutrazol efficacy when incorporated at 15% or 30% by volume in a peat-based substrate when compared with a perlite-amended substrate at the same incorporation volumes. In Expt. 1, a single paclobutrazol drench application of 0, 0.5, 1.0, 2.0, and 4.0 mg·L−1 was applied to ‘Princettia Red’ and ‘Princettia White’ poinsettias (Euphorbia pulcherrima × Euphorbia cornastra). In Expt. 2, two different biochar particle sizes of coarse (<6 mm) and extra coarse (>6 mm) were examined at the same incorporation volumes as Expt. 1 and compared with a perlite-amended substrate at the same incorporation volumes. However, during Expt. 2, continual drench applications at times of irrigation of 0.0, 6.25, 12.5, 25.0, 50, and 100 μg·L−1 (ppb) paclobutrazol were applied to pansy (Viola ×wittrockiana) ‘Matrix Blue Blotch’ and begonia (Begonia ×hybrida) ‘Big Red Bronze Leaf’. The efficacy of paclobutrazol drenches for controlling growth in all species was unaffected by the substrate composition regarding aggregate type or aggregate incorporation rate. Thus, even though biochar is often used for bioremediation and wastewater treatment, it did not negatively impact the efficacy of paclobutrazol drenches at the concentrations used. This research suggests that when biochar is used as an amendment to peatmoss it will not influence paclobutrazol drench efficacy when incorporated up to 30% by volume for the examined species.

A parallel finite element post-processing algorithm for the damped Stokes equations

This paper presents and analyzes a parallel finite element post-processing algorithm for the simulation of Stokes equations with a nonlinear damping term, which integrates the algorithmic advantages of the two-level approach, the partition of unity method and post-processing technique. The most valuable highlights of the present algorithm are that (1) a global continuous approximate solution is generated via the partition of unity method; (2) by adding an extra coarse grid correction step, the smoothness of the approximate solution is improved; (3) it has a good parallel performance since there requires little communication in solving a series of residual problems in the subdomain of interest. We theoretically derive the L2-error estimates both for the approximate velocity and pressure and H1-error estimate for the velocity under some necessary conditions. Meanwhile, we numerically perform various test examples to validate the theoretically predicted convergence rate and illustrate the high efficiency of the proposed algorithm.

Wear phenomena in different cemented carbides during rotary-percussive drilling in reinforced concrete

Rotary-percussive drilling through steel reinforced concrete not only subjects cemented tungsten carbide drill bits to intensive abrasive wear but additionally induces significant microstructural changes in the near-surface regions. These include micro-, meso- and macroscopic cracking; comminution of the WC; delamination of WC-binder interfaces; binder depletion and pore formation; partial WC dissolution and rearrangement; surface decarburization; and the creation of secondary phases within the binder.In this study, the wear phenomena in cemented carbide drill bits with different WC grain sizes (fine to extra coarse), binder contents (6–12 wt%) and binder types (Co, CoNi and Ni) have been documented, analysed and quantified. Noticeable differences between the various grades are evident.A wide range of experimental variables have been investigated covering the large proportion of real-world cases encountered in the application of these drill bits on the construction site. This paper presents a broad overview highlighting how material choice influences wear.

Next generation of Bluelink ocean reanalysis with multiscale data assimilation: BRAN2020

Abstract. BRAN2020 (2020 version of the Bluelink ReANalysis) is an ocean reanalysis that combines observations with an eddy-resolving, near-global ocean general circulation model to produce a four-dimensional estimate of the ocean state. The data assimilation system employed is ensemble optimal interpolation, implemented with a new multiscale approach that constrains the broad-scale ocean properties and the mesoscale circulation in two steps. There is a separation in the scales that are corrected in the two steps: the high-resolution step corrects the mesoscale dynamics in the same way as previous versions of BRAN, while the extra coarse step is effective at correcting biases that develop at large scales. The reanalysis currently spans January 1993 to December 2019 and assimilates observations of in situ temperature and salinity, as well as of satellite sea-level anomaly and sea surface temperature. BRAN2020 is planned to be updated to within months of real time after this initial release, until an updated version of BRAN is available. Reanalysed fields from BRAN2020 generally show much closer agreement to observations than all previous versions with misfits between reanalysed and observed fields reduced by over 30 % for some variables, for subsurface temperature and salinity in particular. The BRAN2020 dataset is comprised of daily averaged fields of temperature, salinity, velocity, mixed-layer depth and sea level. Reanalysed fields realistically represent all of the major current systems within 75∘ S and 75∘ N, excluding processes relating to sea ice but including boundary currents, equatorial circulation, Southern Ocean variability and mesoscale eddies. BRAN2020 is publicly available at https://doi.org/10.25914/6009627c7af03 (Chamberlain et al., 2021b) and is intended for use by the research community.

Achieving high strength-ductility in a wrought Mg–9Gd–3Y–0.5Zr alloy by modifying with minor La addition

Effects of 0.5 wt% La addition on microstructures and mechanical properties of a traditional hot-extruded Mg–9Gd–3Y–0.5Zr alloy were thoroughly investigated in this work. The results indicate that minor La addition obviously improves the alloy’s mechanical performance at room temperature, accomplished an ultra-high tensile yield strength of 480 MPa with the elongation of ~6%, although leading to much lower high-temperature strength. Microstructural analysis reveals that after extrusion, minor La addition leads to a significantly higher level of recrystallization (the volume fraction is improved from 21% to 68%), much finer dynamically recrystallized (DRXed) grains (the average sizes are refined from 4.12 µm to 3.26 µm), and also finer non-recrystallization stripes. La addition promoting recrystallization is mainly attributed to the finer grains and much more intermetallics not only at grain boundaries but also in α-Mg grains of the ingots before extrusion. During peak-aging, minor La addition does not change intermetallics/precipitates in both DRXed grains and non-recrystallized regions except some extra coarse Mg17La2 particles mainly in extrusion stringers. Therefore, minor La addition improving both strength and ductility of the hot-extruded Mg–9Gd–3Y–0.5Zr alloy at room temperature is mainly by grain-refinement strengthening which is also the underlying cause for the lower work hardening coefficient, high-temperature strength but higher ductility.

Modeling and Optimizing the Parameters of Condensers in Split Type Room Air Conditioners

Split type room air conditioners (RACs) are very common nowadays. In Bangladesh, RAC manufacturers employ trial-error prototyping techniques in their design to increase the efficiency of RACs and the profitability of the plant. Computer modeling can be a great help to reduce the cost in the R&D stage to find the optimum design of RACs. In this study, modeling of heat transfer in the condenser of split type RACs employing the techniques of Computational Fluid Dynamics (CFD) was performed. To reduce the computational load the geometry was divided into small sections and geometric symmetries were also taken into account. For the simulation, the geometry and other relevant data were set in such a way so that they commensurate closely with real industrial data. An example data set for validation of simulation results were obtained from an AC manufacturer company, Elite Hitech Industries Ltd. The geometry was built using meshing techniques. Copper and aluminum were selected as materials for tubes and fins, respectively. R-22 was chosen as the refrigerant. Heat transfer and fluid flow were modeled using non-isothermal flow in a multi-physics environment. The main assumptions employed are laminar flow, extra coarse mesh size, constant air inlet temperature, perfect insulation between system and surroundings, and thin layer fins. The temperature distribution and heat transfer efficiency in the condenser, the impact of different refrigerant flow arrangements in the tubes have been studied in detail. This study leads to the finding of efficient refrigerant flow arrangements from the viewpoint of maximum heat transfer.
 Chemical Engineering Research Bulletin 21(2020) 20-25

CGGAN: a context‐guided generative adversarial network for single image dehazing

Image haze removal is highly desired for the application of computer vision. This study proposes a novel context-guided generative adversarial network (CGGAN) for single image dehazing. Of which, a novel new encoder–decoder is employed as the generator. In addition, it consists of a feature-extraction net, a context-extraction net, and a fusion net in sequence. The feature-extraction net acts as an encoder, and is used for extracting haze features. The content-extraction net is a multi-scale parallel pyramid decoder and is used for extracting the deep features of the encoder and generating coarse dehazing image. The fusion net is a decoder and is used for obtaining the final haze-free image. In order to get better dehazing results, multi-scale information obtained during the decoding process of the context extraction decoder is used for guiding the fusion decoder. By introducing an extra coarse decoder to the original encoder–decoder, the CGGAN can make better use of the deep feature information extracted by the encoder. To ensure that the proposed CGGAN works effectively for different haze scenarios, different loss functions are employed for the two decoders. Experiments results show the advantage and the effectiveness of the proposed CGGAN, evidential improvements over existing state-of-the-art methods are obtained.

Scene Segmentation With Dual Relation-Aware Attention Network.

In this article, we propose a Dual Relation-aware Attention Network (DRANet) to handle the task of scene segmentation. How to efficiently exploit context is essential for pixel-level recognition. To address the issue, we adaptively capture contextual information based on the relation-aware attention mechanism. Especially, we append two types of attention modules on the top of the dilated fully convolutional network (FCN), which model the contextual dependencies in spatial and channel dimensions, respectively. In the attention modules, we adopt a self-attention mechanism to model semantic associations between any two pixels or channels. Each pixel or channel can adaptively aggregate context from all pixels or channels according to their correlations. To reduce the high cost of computation and memory caused by the abovementioned pairwise association computation, we further design two types of compact attention modules. In the compact attention modules, each pixel or channel is built into association only with a few numbers of gathering centers and obtains corresponding context aggregation over these gathering centers. Meanwhile, we add a cross-level gating decoder to selectively enhance spatial details that boost the performance of the network. We conduct extensive experiments to validate the effectiveness of our network and achieve new state-of-the-art segmentation performance on four challenging scene segmentation data sets, i.e., Cityscapes, ADE20K, PASCAL Context, and COCO Stuff data sets. In particular, a Mean IoU score of 82.9% on the Cityscapes test set is achieved without using extra coarse annotated data.

Quality control of a metallic dental bur with a diamond coating

Abstract During operation, sterilization and disinfection, the surface working part of dental burs deteriorates. In this study a commercial metallic dental bur with extra coarse gradation (177-250 μ of ceramic embankment), made of a stainless steel were covered with a nickel-diamond composite was examined. The working part of the tool is round-end taper shaped and is intended for crown and bridge preparation. Analysis of microstructure was carried out using Jeol JSM-6610 LV scanning electron microscope with EDX analyzer. After 3 months of operation, the bur can be used for further work in the dental surgery.

Sprayer Setup Affects Dislodgeable 2,4-D Foliar Residue in Hybrid Bermudagrass Athletic Fields

2,4-dimethylamine salt (2,4-D) is a selective broadleaf herbicide commonly applied to turfgrass systems, including athletic fields, which can dislodge from treated vegetation. Building on previous research confirming 2,4-D dislodgeability is affected by management inputs, field research was initiated in 2014 and 2015 in North Carolina and Tennessee to quantify the effects of sprayer setup on dislodgeable 2,4-D foliar residue from hybrid bermudagrass, which is the most common athletic field playing surface in subtropical and tropical climates. More specifically, research evaluated dislodgeable 2,4-D foliar residue following spray applications (2.1 kg ae ha−1) at varying carrier volumes (187, 374, or 748 L ha−1) and nozzles delivering varying droplet sizes (fine=extended range [XR], coarse=drift guard, or extra coarse=air induction extended range [AIXR]). Overall, data suggest minimal 2,4-D dislodge occurs via soccer ball roll (3.6 m) outside the day of application; however, increasing carrier volume and droplet size can further decrease dislodgeable 2,4-D foliar residue. At 2 d after treatment (DAT), 3.87% of applied 2,4-D dislodged when applied at 187 L ha−1compared to 2.05% at 748 L ha−1. Pooled over data from 1 to 6 DAT, 1.59% of applied 2,4-D dislodged following XR nozzle application compared to 1.13% with AIXR nozzle. While these are small numerical differences, dislodgeable residue was measured via one soccer ball roll, which is a repeated process within the sport and the additive effect of sprayer setup treatments can be employed by turfgrass managers to reduce potential human 2,4-D human exposure.

Coarse needle surface potentiates analgesic effect elicited by acupuncture with twirling manipulation in rats with nociceptive pain

BackgroundBiomechanical phenomenon called “needle grasp” through the winding of connective tissue has been proposed as an action mechanism of acupuncture manipulation. The aim of the present study is to verify whether the needle grasp force affects the pain-relieving activity of acupuncture in the tail-flick latency (TFL) and the rat paw formalin tests.MethodsIn order to make different roughness on the acupuncture needle surface, the needles with 0.2 mm-diameter were scratched using silicon carbide sandpapers with the grit numbers of 600 (mild coarse) and 200 (extra coarse). The surface roughness and rotation-induced torque of the scratched needles were then measured by atomic force microscope and Acusensor®, respectively. Rat abdominal wall tissues including insertion site of acupuncture needle were excised after 5 unidirectional rotations of the needles having various degrees of roughness, and the morphological changes of connective tissues were analyzed using hematoxylin and eosin (H-E) staining. Finally, the effects of coarse needle surface on anti-nociception induced by twirling manipulation were tested in rat TFL and formalin test.ResultsIt was observed that the rougher the needle surface, the stronger the needle grasp force and thickness of subcutaneous connective tissue while rotating. TFL increased in proportion to surface roughness of the ground needles 10 min after acupuncture into the Zusanli acupoint (ST36) on rat’s legs. In the rat formalin test, the rougher needle also significantly exerted the larger analgesic effect during both early and late phases compared to non-ground normal needle.ConclusionSurface roughness of the acupuncture needle enhanced an anti-nociceptive activity of acupuncture therapy in rats, which partially supports the mechanical signaling theory through connective tissues in acupuncture manipulation.

Binder phase strengthening of WC–Co alloy through post-sintering treatment

Due to the large mean free paths of the binder phases in extra coarse and super extra coarse cemented carbides, it is necessary to strengthen the binder phase to obtain a well-matched performance of the binder phase and the WC hard phase. A nanoindentation tester, a high-resolution analytical electron microscope and an X-ray diffractometer were used in the study of the Co-based binder phase (the Co) of WC–8.4Co alloy with a grain size of 10.2μm. Specimens with four sequential treatment states, namely, as-sintered, supersolidus liquid-phase quenched, cryogenic, and tempered were analyzed. It is shown that compared with the as sintered state, the elastic modulus (EIT) and nano-indentation Vickers hardness (HV2mN) of the Co in a tempered state increase by 20.0% and 8.7%, respectively; the EIT and HV2mN of the Co in a quenched state increase by 10.1% and 6.9%, respectively. Stable WC/amorphous Co/crystal Co (fcc) interfaces, the mixture of order and disorder structure in nano-scale in the Co accompanied by the local transition of fcc to hcp structure of the Co were observed in the alloy in a tempered state.

Permeability Curves Characteristic Analysis of L Oilfield

The L oilfield Cretaceous (M-I-1), Jurassic Department (Ю-0-3) clastic pore types, including primary porosity, secondary porosity and cracks in three categories, their characteristics and the degree of development. Chalk Department of particles holes and grain dissolution porosity, an average of 53.2%, followed by argillaceous porous and contraction joints, while a small number of particles dissolved pore, showing a small amount of paste particles seam and tensile crack; Jurassic inter-granular holes and intra-granular dissolution porosity is developed, accounting for the porosity as high as 95%, while a small amount of argillaceous porous and granulizing hole and a very small amount of mold holes. L Oilfield Cretaceous and Jurassic reservoirs inter-granular pores, inter-granular dissolution pore, pore throat combination M-I-1, mainly to large - in the hole, micro-throat, Ю-0-3 large - in the hole Extra Coarse - rough throat-based thin throat, Ю-0-1, Jurassic sandstone pore structure better than the Cretaceous.

Micro characteristics of binder phases in WC–Co cemented carbides with Cr–V and Cr–V–RE additives

Taking the advantage of the large mean free paths of the binder phases, we investigated the effect of Cr–V and Cr–V–RE (RE: rare earth) additives on the micro characteristics of the Co-based binder phases (the Cos) in WC–8.4Co cemented carbides with grain sizes larger than 5μm and a narrow two-phase carbon window. It included the crystal structure parameters, composition and morphology. To avoid the interference of WC phase on the analysis, a method of selective electrolysis corrosion of WC was employed. Based on the investigation of the residual Co skeletons, the following facts were established: (1) the sole fcc structure; (2) the quite different solution behavior of V and Cr; (3) the significantly suppressed solid solubility of W and significantly increased solid solubility of W+Cr+V (in atomic fraction) and (4) the formation of fine stairs on the surfaces. A strong ability of Cr–V and Cr–V–RE additives in the grain growth inhibition was observed even though an extra coarse WC raw material was used. The relationship among the solid solubility, lattice parameter and strain in/of the Cos, the magnetic saturation and the grain growth inhibition of the alloys were discussed.

Investigation on the scattering-filling coarse aggregate self-consolidating concrete

To secure good flowability and workability of SCC, the volume fraction of coarse aggregate keep at an extremely low level. A new kind of SCC pouring method named scattering-filling coarse aggregate process was invented: it was method to scatter 20% (volume fraction to the finished concrete) of extra coarse aggregate into the fresh SCC mixture to replace the fresh concrete mixture while the concrete was pouring. A high strength (82 MPa) SCC just composing 360 kg/m3 cement and 120 kg/m3 class F fly ash was prepared with this process. With an increase of the extra coarse aggregate replacing ratio from 0 to 30%, the compressive strength of SCC increased steadily and reached a peak value when this ratio is 20%, then the strength dropped sharply. The drying shrinkage ratio and the chloride ion permeability decreased with the increase of that ratio. The scattering-filling coarse aggregate process can cast high strength SCC with lower cementitious materials content and produce concrete with better performance than the ordinary process.

Impact of sodium chloride on Escherichia coli O157:H7 and Staphylococcus aureus analysed using transmission electron microscopy

Abundant literature information is available on sodium chloride, NaCl, as an antimicrobial and a preservative, however, information on NaCl effects on bacterial cell morphology is lacking. The effect of NaCl, on Escherichia coli O157:H7 and Staphylococcus aureus cells individually grown in a laboratory medium was examined using transmission electron microscopy (TEM). Cultures were grown in brain heart infusion (BHI) broth containing dissolved 0%, 5%, or 10% (w/v) commercially obtained fine (FN) and extra coarse (EC) grade granular NaCl. The pathogens were incubated at 35 °C for 12 and 24 h. Then, a mixture of five strains of each pathogen per treatment was prepared. Samples were centrifuged, pellets collected, fixed immediately with glutaraldehyde, and prepared for TEM examination. Cells morphology on TEM micrographs verified that the magnitude of morphological damage to E. coli O157:H7 cells was significantly greater than that of S. aureus cells. More cell injury occurred as NaCl concentration increased from 5% to 10%. Generally, S. aureus maintained its cellular structure and no severe cell wall or plasma membrane damage and/or shrinkage was observed. At 10% NaCl, the damage to E. coli O157:H7 cells was extensive, and the pathogen seemed to have lost its cellular integrity. Although NaCl affected the morphology of E. coli O157:H7 and S. aureus, the coarse grade of NaCl seemed to have a milder effect with respect to cell damage, especially on S. aureus. The 24 h-old cultures were more susceptible to NaCl treatment compared to the 12 h-old cells. Thus, the age of the cells has an impact on their resistance to salt—the environmental stressor.

Hierarchical Temporal Specifications of Dynamically Reconfigurable Component Based Systems

We study how temporal specifications of reconfigurable component based systems can be hierarchically organised. We do so by extending a previously introduced declarative prototypical language to admit the definition of hierarchical subsystems. Each subsystem has an internal architecture, composed of its internal interacting (simpler) subsystems, and basic components. The internal architecture of a subsystem can change at “run time” by means of reconfiguration operations. The notion of subsystem provides an extra coarse grained unit of modularisation, that complements that of components. Since component interaction is achieved by means of coordination, a component or subsystem can be represented by a logical theory isolated from the rest of the system. This, in combination with the possibility of hierarchically organising a specification, has a special impact in reasoning, since it allows us to further localise the proof efforts to the relevant subparts of a specification.

Influence of Extra Coarse Grains on the Creep Properties of 9 Percent CrMoV (P91) Steel Weldment

With modern welding methods, satisfactory microstructures in 9%CrMoV (P91) steel can be obtained with a modest variation in hardness and prior austenite grain size. However, there is always a risk that significant deviations in the properties can be obtained, if the welding parameters are not optimized. In the present paper the role of extra coarse grains in the heat affected zone (HAZ) has been studied. Creep tests were carried out at 600°C for parent metal, weld metal, cross weld, simulated extra coarse grained HAZ, and simulated intercritical HAZ of a 9%CrMoV (P91) steel. The parent metal, the cross welds, the weld metal, and the simulated intercritical HAZ had about the same rupture strength except at long rupture times, where the values for the cross welds were considerably lower. In the cross welds, rupture took place in the intercritical HAZ at longer times (Type IV cracking). The simulated extra coarse grains gave considerably longer rupture times, lower strain rate and lower creep ductility than the parent metal and the weld metal. The creep strain behavior was successfully analyzed using the Omega model where the log creep strain rate is linear in the creep strain.

Fatigue crack growth mechanisms in Ti6242 lamellar microstructures: Influence of loading frequency and temperature

Fatigue crack growth experiments were carried out on Ti6242 alloy with large colony size. The alloy was heat treated to provide three different lamella size; fine, coarse, and extra coarse. Tests were conducted at two temperatures, 520 °C and 595 °C, using two loading frequencies, 10 and 0.05 Hz. The latter frequency was examined with and without a 300-second hold time. All tests were performed in air environment and at a stress ratio of 0.1. This study shows that at 520 °C, the Fatigue crack growth rate (FCGR) is not significantly influenced by changes in the microstructure. For 0.05 Hz/low ΔK, however, the FCGR is higher in the fine lamellar microstructure and is accompanied by- the appearance of a plateau, which disappears in the extra large lamella microstructure. Furthermore, the addition of a 300-second hold time does not alter the crack growth rate. At 595 °C, while the general level of the FCGR is higher than that at 520 °C, the effects of loading frequency and hold time remain similar to those reported at the lower temperature. Unlike the results at 520 °C, however, the FCGR at low δK is not influenced by variations in lamellar microstructure. Under all test conditions, the fatigue process is predominantly controlled by one single mechanism associated with transcolony fracture and formation of quasi-cleavage facets. The fatigue crack growth results and the associated fracture behavior as obtained in this study are correlated to the crack-tip shear activity and transmission at the α/β interfaces. A general hypothesis accounting for the role of loading frequency, temperature, and microstructure on the observed cracking mechanisms is presented.