Specific Shape Research Articles

Recreating an Amazonian Ancestral Biodesign Technique

Abstract This study investigates an ancestral Biodesign technique associated with the fruits of the Amazonian tree Crescentia cujete. For centuries, Amazonian artisans have transformed these fruits into objects named cuias, which serve mainly as containers. Despite the continued practice of cuias production, a specific shaping technique discovered in historical accounts remains unknown and unused by contemporary artisans. The paper reports the recreation of this technique considering the ancestral ethos underpinning these traditions. A mixed-method approach has combined historical and museum research, direct interaction with trees in a bioeconomy context, and participatory observation of traditional artisans’ production. The findings reveal the ancient practice of “Growing Design” with that tree and other practices that resonate with Biodesign, establishing a connection between this field and indigenous knowledge. This study highlights the underappreciation of indigenous objects and techniques, emphasizing the potential that emerges from understanding the alignment of certain ancestral wisdom with Biodesign principles, such as amplifying indigenous heritage and opening new possibilities in design.

Phase Fraction Estimation Using Measured Dilation, a Lattice Parameter Model, and a Curve-Fitting Method

Dilatometry is a measurement frequently used to analyze phase transformations in steels during austenite decomposition. Such analyses are essential for the design of heat treatments and for determining the final phase fractions. This paper presents a simple and systematic method to estimate the evolution of the non-measurable phase fraction of ferrite, pearlite, bainite, and martensite during Continuous Cooling Transformation (CCT) experiments. The optimization-based method uses the measured dilation curve, a lattice parameter model, and a semi-empirical curve-fitting method. The latter assumes specific shapes of the transformation rates. The proposed approach can reconstruct the dilation curve and estimate the phase fractions with high accuracy.

Probing spin waves in Co3O4 nanoparticles for magnonics applications.

The magnetic properties of spinel nanoparticles can be controlled by synthesizing particles of a specific shape and size. The synthesized nanorods, nanodots and cubic nanoparticles have different crystal planes selectively exposed on the surface. The surface effects on the static magnetic properties are well documented, while their influence on spin waves dispersion is still being debated. Our ability to manipulate spin waves using surface and defect engineering in magnetic nanoparticles is the key to designing magnonic devices. We synthesized cubic and spherical nanoparticles of a classical antiferromagnetic material Co3O4 to study the shape and size effects on their static and dynamic magnetic proprieties. Using a combination of experimental methods, we probed the magnetic and crystal structures of our samples and directly measured spin wave dispersions using inelastic neutron scattering. We found a weak, but unquestionable, increase in exchange interactions for the cubic nanoparticles as compared to spherical nanoparticle and bulk powder reference samples. Interestingly, the exchange interactions in spherical nanoparticles have bulk-like properties, despite a ferromagnetic contribution from canted surface spins.

Wymagania stawiane zabezpieczeniom różnicowoprądowym przeznaczonym do systemów ładowania pojazdów elektrycznych

The properties of residual current devices have been presented from the point of view of their ability to detect a specific shape of the residual current waveform. Moreover, the standard requirements relating to residual current protection used in electric vehicle charging installations have been pointed out. The operating characteristics of the IC-CPD and RDC-DD protections, which are intended for charging electric vehicles in mode 2 and mode 3, respectively, have been also discussed.

Re-examining the Key Issues Concerning the Craftworks Uncovered from Tonggung Palace and Wŏlchi Pond in Kyŏngju

The excavation of Wŏlchi pond in Kyŏngju has yielded numerous craftworks that offer crucial information about Silla’s crafts. However, due to damage or missing parts, it is difficult to fully understand the nature of some items. Additionally, there are some findings whose appearance and conditions at the time of discovery remain unidentifiable. Therefore, over 50 years since the initial excavation in 1975, it is necessary to re-examine the current key issues and discuss the future directions of studies concerning the discoveries from Tonggung Palace and Wŏlchi pond. Firstly, I examined specific shapes and production techniques that are only observed in the findings from Wŏlchi pond. Further, I investigated the usage, and manufacture and decorative techniques of crystals and various objects made of bone and horn produced in Kyŏngju. I proposed the correct function of the <i>Lacquered Flower-shaped Ornament</i> as a portable shrine and additionally presented the <i>Gilt-Bronze Wick Trimmer</i>, suitably made for its role, as evidence of the new culture involving candles. When further research is conducted into the uses, production techniques, and decorative designs of the items found in incomplete form, such as <i>Bamboo-shaped Ornament, Bone Fragment with Flower and Bird Design</i>, and <i>Lacquered Plate with Flower and Foliage Design</i>, we may be able to understand more aspects of the craft culture of Unified Silla. Furthermore, the recovered items from Wŏlchi pond exhibiting various designs, such as birds holding flowers in their beaks (<i>hamjomun</i>), flower medallions (<i>bosanghwamun</i>), and rows of beads (<i>yeonjumun</i>), provide evidence that Unified Silla shared a common decorative trend with Tang China and Nara Japan. Tonggung palace and Wŏlchi pond are valuable resources for the history of decorative patterns in Korea.

Experimental study and numerical prediction of the bond-slip law for concrete elements strengthened with FRP using metaheuristic algorithm

Modeling an accurate bond-slip model between concrete and reinforcement is a significant challenge in fiber reinforced polymer (FRP) strengthened reinforced concrete (RC). This paper presents a novel method for developing and validating an accurate bond-slip model. By employing a numerical procedure based on the finite difference method and a metaheuristic optimization algorithm, this method eliminates the need for a specific bond-slip law shape. This unique feature enables the prediction of bond-slip laws for various strengthening methods, including EBR and NSM, as demonstrated in this study. Furthermore, the methodology allows for the prediction of bond-slip laws associated with premature failure. The numerical and experimental results obtained confirm the accuracy of the methodology.

Variation in the contact angle of zinc oxide nanostructures with the passage of time

The development of clean materials has increased; these materials present a surface modification that makes them neat and easy to clean. The direct improvement in the impermeability of materials is generated by manipulating the structures present on the surfaces, generating selfcleaning coatings (hydrophobic surfaces). The modification can be developed by superficially synthesizing nanostructures of specific shapes on some solid that prevent the passage of liquids between them, for example, zinc oxide nanowires that exhibit a high contact angle due to their geometry. The synthesis of these nanostructures is low cost and simple, making it a viable alternative to achieve hydrophobic surfaces that are selfcleaning. The present work shows how the synthesis factors of these nanostructures impact their contact angle. Hydrophobic contact angles were obtained in most samples and nanostructures averaging 290 nm and average lengths of 2.2 μm.

Effectiveness of Additive Manufactured Titanium Implants in the Reconstruction of Large Cranial Defects: Case Series and Review of Literature

Abstract Introduction Replacement of lost soft and hard tissues of the human body has always been a daunting task across all surgical specialties. Reconstruction of a cranial deformity is challenging due to the functional and cosmetic requirements. A major constraint with large cranial bony deformity reconstruction is the nonavailability of graft of a specific shape and size. Materials and Method A total of four cases of large cranial defects which included three cases of unilateral and one case of midline residual deformity were reconstructed at our center using customized titanium implants. These implants were fabricated using additive manufacturing/3D printing technology utilizing computerized tomographic data. Conclusion The additively manufactured titanium implants appear to be a viable option in the reconstruction of large cranial defects.

Harvest maturity stage affects watercore dissipation and postharvest quality deterioration of watercore 'Fuji' apples

Watercore 'Fuji' apples, with their special watercore shape and unique flavor and texture, are a very popular specialty fruit in the Asian markets. However, watercore disappearance and quality deterioration of apples during postharvest storage are serious problems. In this study, we compared the differences among three harvest maturity stages of apples in watercore dissipation and fruit quality deterioration. In this study, the physiochemical attributes (visual quality, watercore incidence, and firmness), flavor substances (TSS content, TA content, and TSS/TA), aroma volatiles, and cellular structure were analyzed in 'Fuji' apple fruits of low maturity (LM) at early harvest stage, medium maturity (MM) at mid harvest stage, and high maturity (HM) at late harvest stage, during a cold storage at 0 ± 1 °C for 120 d. The results showed that harvest maturity stage had a significant effect on postharvest storage quality parameters of watercore 'Fuji' apples. Specifically, L*, b*, firmness, and TA values of the flesh decreased significantly from the LM to the HM levels. However, the watercore incidence of apples significantly increased from LM to HM levels. Moreover, the parameters including L*, b*, firmenss, TA, and watercore incidence of apples with different harvest maturity stages gradually decreased as the storage time increased. In contrast, the TSS, TSS/TA, and a* values showed an increasing trend from LM to HM apples. In particular, the TSS tended to increase first and decrease after 60 d of storage. Moreover, the microstructure and cellular structure gradually deformed as the structural porosity and cell size decreased from LM to HM apples. Furthermore, the microstructure of the watercore and non-watercore sites is significantly different. Meanwhile, the content of soluble sugars and aroma volatiles increased with the advancing maturity. Non-watercore sites of apples with the same level of maturity contained higher levels of sucrose, fructose, maltose, and sorbitol than watercore sites. Furthermore, the MM apples maintained better sensory qualities during the shelf life after cold storage. Overall, the MM apples showed higher quality and were more acceptable to consumers, which suggested watercore 'Fuji' apples from mid harvest stage showed the optimal harvest-ready maturity for post-harvest long-term cold storage.

Triple‐chain segments regulation enable shape memory and photo deformation of smart polyimide

AbstractIntegration of controllable deformation with excellent thermal stability, mechanical, and insulation properties can greatly expand the versatility of smart polyimides (PIs). However, the unique molecular structure of PI makes it difficult for its molecular chain to move, which is not conducive to the reversible transformation of highly stable PI under environmental conditions. In this study, a PI film integrating shape memory and photo deformation is prepared by constructing a chemical network with PI oligomer as the hard, hexamethylene diisocyanate (HDI) as the soft, and azobenzene as the functional chain segment. The PI films still have a high glass transition temperature Tg ~ 225°C, a high Young's modulus E ~ 3.5 GPa, and a good breakdown strength Eb ~ 176 kV/mm. Moreover, as the network point of the chemical network, the trifunctional crosslinking agent makes the PI produce the shape memory effect induced by light and heat. UV light can drive crosslinked photoresponsivity PI film to have special shape transformation under specific conditions, using azobenzene as photoresponsivity group. This study provides a new idea for the preparation of multifunctional PI, which makes it potentially applicable in the field of smart electric and electronic engineering.

Numerical analysis of dynamic acoustic resonance with deformed liquid surfaces: the acoustic fountain

Applying a focused ultrasonic field on a free liquid surface results in its growth eventually leading to the so-called acoustic fountain. In this work, a numerical approach is presented to further increase the understanding of the acoustic fountain phenomenon. The developed simulation method enables the prediction of the free surface motion and the dynamic acoustic field in the moving liquid. The dynamic system is a balance between inertia, surface tension and the acoustic radiation force, and its nonlinearity is demonstrated by studying the relation between the ultrasonic excitation amplitude and corresponding liquid deformation. We show that dynamic resonance is the main mechanism causing the specific acoustic fountain shapes, and the analysis of the dynamic acoustic pressure allows us to predict Faraday-instability atomisation. We show that strong resonance peaks cause atomisation bursts and strong transient deformations corresponding to previously reported experimental observations. The quantitative prediction of the dynamic acoustic pressure enables us to assess the potential of cavitation generation in acoustic fountains. The observed local high acoustic pressures above both the cavitation and the atomisation threshold hint at the coexistence of these two phenomena in acoustic fountains.

MECHANISMS OF ATTENTIONAL CONTROL AND SUPPRESSION IN AGING

Abstract Attentional control plays a crucial role in our daily lives by allowing our brains to selectively process relevant information while filtering out task-irrelevant distractions. Due to aging, older adults have demonstrated a heightened propensity to be more distractible. This decreased ability to regulate attention has been attributed to an inability to inhibit task-irrelevant salient stimuli. However, the specific mechanisms that underlie this age-related alteration remain unclear. In this study, we utilized a visual search paradigm that directly measures mechanisms of attentional suppression to test our hypothesis that older adults demonstrate reduced capabilities to suppress task-irrelevant information. Young adults (aged 18-35) and older adults (aged 50-80) were tasked to utilize goal-directed attentional control by fixating at a specific target shape. Critically, in some trials, individuals were exposed to a salient color shape that acted as a singleton distractor. While young adults show the ability to suppress attentional allocation to this salient distractor in this paradigm, we hypothesized that older adults would demonstrate attentional capture by this salient distractor. Our findings revealed that older adults made significantly fewer first-fixations towards the target, demonstrating a marked impairment with goal-directed attentional control. Surprisingly, older adults still made fewer fixations toward the distractor in comparison to non-targets, demonstrating that older adults sustained the ability to suppress irrelevant distractors. These findings raise important questions on the mechanisms that underlie increased distractibility in aging and oculomotor attentional control.

Thin-walled tapered conformable low-pressure tanks: Concept and principles

In pressure tank design, structural efficiency or the ratio of pressurized volume to structural mass is fundamental and implies a specific shape, such as a cylindrical or spherical layout. However, this axi-symmetric layout may be not conform to the enveloping shape. Previous investigations developed a conformable tank concept with a multi-bubble axi-symmetric layout, called a multi-lobe, multi-cell or multi-bubble tank, but structural design and analysis are limited to intersecting cylindrical, spherical or toroidal shells. The objective of this research is to increase the volumetric efficiency of multi-bubble tanks even further through the introduction of a conical shell. An integral analytical formulation of tank topology and explicit expression of equilibrium are provided in order to design a structurally efficient tapered multi-bubble tank under low differential pressure. The result is expressed in a geometric rule that is applicable for tapered multi-bubble tanks of any eligible shape.

Characteristics of flow field and various resistances of sandglass-type FPSO with special shape during towing process

For the new concept of floating production, storage and offloading unit (FPSO), the unique sandglass-type shape of its floating body can effectively reduce heave motion responses. However, this design feature may also generate distinct flow characteristics during towing. In this paper, the numerical method was established and validated to successfully predict the towing performance of the sandglass-type model by comparing it with the model experiment of a polar ocean nuclear energy platform with the sandglass-type shape. On this basis, the analysis incorporates both a local model of the underwater body without a free surface and a global model of the floating body with a free surface to analyze towing resistances. Specifically, the paper focuses on the frictional resistance and pressure resistance of sandglass-type models versus various draughts. Furthermore, the influence of free surface on various kinds of resistances and the towing resistances of sandglass-type FPSO with different speeds were studied. Finally, concluding remarks and future perspectives are presented.

Semi-Supervised Variational Autoencoders for Out-of-Distribution Generation.

Humans are able to quickly adapt to new situations, learn effectively with limited data, and create unique combinations of basic concepts. In contrast, generalizing out-of-distribution (OOD) data and achieving combinatorial generalizations are fundamental challenges for machine learning models. Moreover, obtaining high-quality labeled examples can be very time-consuming and expensive, particularly when specialized skills are required for labeling. To address these issues, we propose BtVAE, a method that utilizes conditional VAE models to achieve combinatorial generalization in certain scenarios and consequently to generate out-of-distribution (OOD) data in a semi-supervised manner. Unlike previous approaches that use new factors of variation during testing, our method uses only existing attributes from the training data but in ways that were not seen during training (e.g., small objects of a specific shape during training and large objects of the same shape during testing).

Fabrication of porous X-shaped Fe3O4@C core-shell structures for tunable microwave absorption

Designing porous materials with low density and high specific surface area is one of the strategies to obtain excellent wave absorbing properties. In this study, the carbon-coated porous X-shaped Fe3O4 composites used as microwave absorption materials were prepared by heat treatment of FeOOH@Polydopamine (PDA) core-shell precursors. It revealed that the X-shaped Fe3O4 core showed improved magnetic loss in GHz band due to its special shape anisotropy and large specific surface area. In addition, the modification of carbon enabled the Fe3O4 absorbers to have stronger polarization and higher electrical conductivity. The composites exhibited great freedom in performance tunability, allowing for strong absorption (RL<−40 dB) at different frequencies. For composites with thick carbon shell, the reflection loss reached the optimal value of − 64.92 dB at 15.04 GHz at the thickness of 1.75 mm, and the effective bandwidth was up to 4.64 GHz (13.04–17.68 GHz). The impressive performance of the as-prepared Fe3O4 @C core-shell composites was mainly attributed to the complementary behaviors of strong dielectric loss and magnetic loss.

Tensile Failure Behaviors of Adhesively Bonded Structure Based on In Situ X-ray CT and FEA.

Adhesive bonding plays a pivotal role in structural connections, yet the bonding strength is notably affected by the presence of pore defects. However, the invisibility of interior pores severely poses a challenge to understanding their influence on tensile failure behaviors under loading. In this study, we present a pioneering investigation into the real-time micro-failure mechanisms of adhesively bonded structures using in situ X-ray micro-CT. Moreover, the high-precision finite element analysis (FEA) of stress distribution is realized by establishing the real adhesive layer model based on micro-CT slices. The findings unveil that pores induce stress concentration within the adhesive layer during the tensile process, with stress levels significantly contingent upon pore sizes rather than their specific shapes. Consequently, larger pores initiate and propagate cracks along their paths, ultimately culminating in the failure of adhesively bonded structures. These outcomes serve as a significant stride in elucidating how pore defects affect the bonding performance of adhesively bonded structures, offering invaluable insights into their mechanisms.

Effects of Different Die Metals on the Performance and Friction and Wear of Composite Materials during the Extrusion Process.

Extrusion technology is widely utilized in the rubber processing industry, with the extruder serving as the core equipment. As mixed rubber enters the extruder, it undergoes conveyance and plasticization, ultimately forming specific shapes and dimensions upon extrusion. The extruder head is a crucial component, playing a key role in achieving the final product's required size and shape. Factors such as its structure, materials, and manufacturing processes significantly impact the efficiency, product quality, and sustainability of the extrusion process. However, prolonged operation leads to severe wear of the extruder head, adversely affecting rubber product quality. Additionally, extruder head processing poses challenges, with maintenance and repair being complex procedures. Therefore, exploring a wear-resistant, long-lasting metal material for the extruder head without compromising mixed rubber performance is essential. This study focuses on severely worn extruder head metal materials, comparing wear levels after friction with STELLITE 6 alloy, Hastelloy C-276 alloy, 38CrMoAlA, and tungsten carbide with composite rubber. Results show that compared to the NR/BR composite material after Hastelloy C-276 alloy friction, rubber Payne effect increased by 4.4% (38CrMoAl), 3.2% (STELLITE 6), and 4.6% (tungsten carbide). Similarly, rubber dispersion decreased by 9.4% (38CrMoAl), 4.7% (STELLITE 6), and 9.8% (tungsten carbide). Rolling resistance increased by 18.1% (38CrMoAl), 16% (STELLITE 6), and 23.4% (tungsten carbide). Friction coefficient increased by 3.5% (38CrMoAl), 2.8% (STELLITE 6), and 4.3% (tungsten carbide). Wear volume increased by 39.3% (38CrMoAl), 45.3% (STELLITE 6), and 48.9% (tungsten carbide). Specifically, using Hastelloy C-276 alloy as the extruder head metal material yields the best NR/BR composite material dispersion, highest ten times tear strength, excellent anti-wet skid resistance, and minimum rolling resistance. Conversely, using the other alloys results in varying reductions in the physical and mechanical properties of NR/BR composite materials. This research is crucial for improving rubber product quality and extending extruder head lifespan.

Calculation method for the ultimate bearing capacity of pressure-cast-in-situ pile with spray-expanded frustum

In this paper, the new type of Pressure-cast-in-situ pile with spray-expanded frustum (PPSF) developed by the authors is composed of pile body, ribbed plate, and expanded body with double frustum. The PPSF has the advantages of high bearing capacity, small settlement, high construction speed, and significant economic and environmental benefits. To evaluate the ultimate bearing capacity of PPSF, a calculation method is proposed considering the special shape of PPSF. The ultimate bearing capacity of PPSF is considered as the sum of three parts, e.g., the ultimate bearing capacity of expanded body with double frustum, the ultimate skin friction of pile body, and the ultimate end resistance of pile base. The failure mode of the soil around the expanded body with double frustum is described based on the Meyerhof’s bearing capacity theory. The calculation formula for the ultimate bearing capacity of the expanded body with double frustum is established using the sliding block balance method. The rationality of the calculation method is verified by three cases.

An examination of the use and outcomes of readiness assessments, retention policies, and title 1 funding for kindergarten children in the United States

The current study examined the prevalence and usage of three theoretically informed school-level policies, namely the use of readiness assessments, retention policies, and Title I funds in kindergarten classrooms across the United States. Using the nationally representative Early Childhood Longitudinal Study Kindergarten Class of 2011, we examined whether these school-level policies in kindergarten were related to children's academic learning both generally, and specifically for those who had attended pre-K. Results revealed that the use of kindergarten readiness assessments, kindergarten retention policies, and Title I funds in kindergarten were widespread across the nation. However, application and usage of these school-level policies were varied. Moreover, these school-level policies were generally not associated with children's academic learning broadly or differentially for those who had attended pre-K in the year before kindergarten. This study establishes a national snapshot of the kindergarten landscape in the United States and opens a door for future research to continue to explore how kindergarten specific school-level policies shape children's learning.