Types Of Cores Research Articles

Integrated Stress Sensors for Humidity Performance Drift Analysis and Compensation in Inertial Measurement Units

Microelectromechanical devices are known to be sensitive to ambient humidity. This is especially true for devices in moisture sensitive plastic packages such as consumer targeted inertial measurement units. Stress and deformation based effects are shown to be a main contributor to humidity related effects such as performance and offset drifts. This paper shows that stress sensing units embedded in the mechanically coupled electronic control circuitry can be utilized to detect and compensate stress based humidity performance drifts of plastic packaged inertial measurement units. Next to the utilized stress sensor cells themselves a compensation approach is presented, that corrects the humidity based scale factor drift of a MEMS angular rate sensor while a humidity load is applied. This is achieved by finding a symbolic compensation function, which predicts the moisture induced scale factor drift, based only on the stress values within the electronic control circuitry, utilizing genetic symbolic regression. It is demonstrated that, using stress sensors, the humidity induced scale factor drift of two different gyroscope core types can be reduced by a factor of 3, which holds true for parts coming from separate assembly lots. [2022-0013]

TRANSFORMATION OF RURAL HOMESTEADS IN THE URBAN FRINGE AREAS OF BANGLADESH: A CASE OF KAKON HUT, RAJSHAHI

The early agrarian community was established in the northern part of Bangladesh because of its unique Barind tract formation. Rural homesteads were the core building block of these settlements. Though 70% of Bangladeshi still live in rural areas, the rural homesteads are being transformed rapidly. Many socio-economic indicators such as population density, limited expansion opportunity, access to modern technology and diverse types of materials and many more are working as a core driving force behind these changes. This article investigates the transformation pattern of the rural homesteads in Kakon Hut Paurashava of Godagari Upazilla in Rajshahi District, in terms of both spatial pattern and construction materials, to develop an in-depth understanding of the impact of adaptation of modern techniques, technologies, and materials in the urban fringe areas. This research is based on an empirical research strategy and consequently progressed through qualitative data collection, observation, questionary survey, and key person interviews. The study produces a thorough analysis of three core types of homesteads in the site area. Finally, a comparative analysis of traditional homesteads with the existing types that have gone through the transformation process is produced to identify the spatial and material transformation in these settlements.

On the influence of manufacturing parameters on buckling and modal properties of sandwich composite structures

Sandwich structures with honeycomb cores are widely used in several applications given their promising properties, like high strength, light weight, and specific stiffness. However, these unique structures present complex behavior with failure modes that are not trivial when subjected to different loading conditions. Evaluation studies about the structural performance and failure modes of honeycomb sandwich structures with different face sheets and cores in static and dynamic conditions are scarce. Therefore, the structural behavior and failure modes of different honeycomb sandwich structures need to be evaluated to promote optimal performance in accordance with project requirements. This study seeks to characterize the structural behavior of different sandwich structures with honeycomb cores using a complete experimental comparative study. First, combinations of different types of cores and face sheets were elaborated using the Design of Experiments Method with Factorial Design, and then both the static and dynamic experimental tests were performed to obtain response variables and failure modes. The results showed that a polypropylene core in sandwich structures can increase damping. The sandwich structures manufactured with glass/aramid hybrid fabrics on the face sheets showed high strength under bending and buckling conditions, supporting a maximum bending loading of 1989 N and a maximum buckling loading of 12,700 N. Most sandwich structures had failure modes in “semi-circle” shapes. Only sandwich structures with glass fabric face sheets have failure modes in “V” shapes. Lastly, statistical results revealed that the type of core design variable contributed more to the response variability and was responsible for significantly changing the properties of stiffness, structural mass, and damping.

RT-SEAT: A hybrid approach based real-time scheduler for energy and temperature efficient heterogeneous multicore platforms

The demand for heterogeneous multicore platforms is growing at a rapid pace in modern gadgets. Such platforms help cater to various types of applications and thus provide high resource utilization. As each task has a different execution time on different types of cores, it is very challenging to schedule tasks on such platforms. With the advancement in technology, it has become imperative to manage energy consumption and temperatures of cores in multicore platforms. Hence, in this work, we propose RT-SEAT, a hybrid real-time scheduler for energy and temperature-efficient heterogeneous multicore systems. Through extensive experimental analysis, we have found that RT-SEAT is able to schedule more tasks (up to 46.75%), save more energy (up to 6.89%), and reduce the average temperature of the cores by 20.45%, when the system workload varies from 50% to 100%, with respect to the state-of-the-art.

On uncertainty modeling of thermoelastic vibration for porous nanosandwich beams with gradient core based on nonlocal higher order beam model

In the present paper, the size-dependent random thermoelastic vibration analysis of porous nanosandwich beams with gradient core are demonstrated based on the nonlocal higher order beam model. The nonlocal elasticity theory incorporation with the higher order shear deformation theory is used to describe the kinematic and constitutive relations. The governing equations are obtained from minimum potential energy principle. The finite element method is used to solve the governing equations. Three types of the FG sandwich nanobeams with three types of porous cores are taken into account, and the influences of these structures and porosity types on the deterministic and stochastic behavior of sandwich beams are thoroughly discussed. Initially convergence and validation study is preformed to validate the present theoretical model by comparing the present results with the several previous works and Monte Carlo Simulation (MCS). Further, a comprehensive parametric study is performed to demonstrate the influence of the length to thickness ratio, degree of uncertainty in the material properties, nonlocal parameter, porosity distribution type, porosity volume fraction, temperature change, and gradation of material on the deterministic and stochastic behaviors of the FG nanosandwich beams. The developed model and computed results may be useful in the precise and reliable design of the components of nanodevices and systems.

Low velocity impact behaviour and mechanical properties of sandwich panels with cores made from Tetra Pak waste

Sandwich panels were fabricated with aluminium faces and two different types of cores: (i) the PAC (high- and low-density polyethylene-aluminium-cellulose) core made from recycled Tetra Pak and high-density polyethylene (HDPE) containers, and (ii) the PAL (low-density polyethylene-aluminium) core produced with only recycled Tetra Pak containers. The tensile and compression tests showed that the PAC core had higher stiffness and lower ductility than the PAL core. The PAC core sandwich panel and the PAL core sandwich panel had similar tensile stiffness; however, the PALS panel exhibited higher ductility. Both sandwich panels had a similar flexural response, dominated by the aluminium sheet behaviour. The PAC core had lower thermal conductivity than the PAL core, attributed to the high cellulose content in the PAC core. The impact test results showed that for impact energies of 10 J and higher, where more extensive core deformation was observed, the peak force of the PALS panels was larger than that of the PACS panels for any given level of absorbed energy. This behaviour demonstrated the higher load-carrying capacity of the PALS panels, attributed to the higher ductility of the PAL core. In addition, the PALS panel exhibited higher penetration threshold energy than the PACS panel.

Soft Error Effects on Arm Microprocessors: Early Estimations versus Chip Measurements

Extensive research efforts are being carried out to evaluate and improve the reliability of computing devices either through beam experiments or simulation-based fault injection. Unfortunately, it is still largely unclear to which extend fault injection can provide an accurate error rate estimation at early stages and if beam experiments can be used to identify the weakest resources in a device. The importance and challenges associated with a timely, but yet realistic reliability evaluation grow with the increase of complexity in both the hardware domain, with the integration of different types of cores in an SoC (System-on-Chip), and the software domain, with the OS (operating system) required to take full advantage of the available resources. In this paper, we combine and analyze data gathered with extensive beam experiments (on the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">final</i> physical CPU hardware) and microarchitectural fault injections (on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">early</i> microarchitectural CPU models). We target a standalone Arm Cortex-A5 CPU and an Arm Cortex-A9 CPU integrated into an SoC and evaluate their reliability in bare-metal and Linux-based configurations. Combining experimental data that covers more than 18 million years of device time with the result of more than 176,000 injections we find that both the SoC integration and the presence of the OS increase the system DUEs (Detected Unrecoverable Errors) rate (for different reasons) but do not significantly impact the SDCs (Silent Data Corruptions) rate which is solely attributed to the CPU core. Our reliability analysis demonstrates that even considering SoC integration and OS inclusion, early, pre-silicon microarchitecture-level fault injection delivers accurate SDC rates estimations and lower bounds for the DUE rates.

Dopant-free small molecule hole transport materials based on triphenylamine derivatives for perovskite solar cells

In the past decade, perovskite solar cells have become a promising candidate in the photovoltaic industry owing to their high power conversion efficiency that surpasses 25%. However, there are certain limitations that have hindered the development and full-scale practical application of these cells, including the high cost and degradation of perovskite caused by the dopants. Hence, there is an urgent need to develop dopant-free hole transport materials (HTMs). In recent years, HTMs based on triphenylamine (TPA-HTMs) are receiving growing interest owing to their high hole mobility, excellent film formation, and suitable energy levels. The literature here covers work relevant to TPA-HTMs in the last five years. They have been classified according to different core types. The correlations between performance and structure are summarized, and the future development trend of TPA-HTMs is highlighted.

McCARD Criticality Benchmark Analyses with Various Evaluated Nuclear Data Libraries

International Criticality Safety Benchmark Evaluation Project (ICSBEP) criticality analyses were conducted using the McCARD Monte Carlo code for 85 selected benchmark problems with 7 evaluated nuclear data libraries (ENDLs): ENDF/B-VII.1, ENDF/B-VIII.0, JENDL-4.0, JENDL-5.0, JEFF-3.3, TENDL-2021, and CENDL-3.2. Regarding the analyses, it was confirmed that the keff results are sensitive to the ENDL. It is noted that the new-version ENDLs show better performance in the fast benchmark cases, while on the other hand, there are no significant differences in keff among the different ENDLs in the thermal benchmark cases. The sensitivity of the keff results depending on the ENDL may impact nuclear core design parameters such as the shutdown margin, critical boron concentration, and power defects. This study and keff results will be a good reference in the development of new types of nuclear cores or new design codes.

Enhanced suppression of saprotrophs by ectomycorrhizal fungi under high level of nitrogen fertilization

Ectomycorrhizal fungi (EMF) are widespread in northern conifer forests. By competing with the free-living saprotrophic fungal and bacterial communities for limited soil nitrogen, EMF are expected to suppress litter decomposition and thus drive soil carbon accumulation. The EMF may also stimulate rhizosphere microbial growth through inputs of labile plant carbon, and subsequently contribute to the soil carbon pool via microbial necromass. Here we examined the relative strength of these two potential EMF effects in a northern conifer plantation of the Saihanba Forest, the largest plantation in China. The soil fungal and bacterial biomass, as well as their respiration, were quantified within the two types of soil cores that either allow or exclude the ingrowth of EMF. We also set up a nitrogen fertilization gradient (0, 5, 10, 15 g N m–2 y–1) in this plantation to quantify the influence of external inorganic nitrogen on the EMF effects. We found evidence that EMF inhibit the overall fungal and bacteria biomass, confirming the suppression of saprotrophs by EMF. In addition, high levels of external nitrogen fertilization (15 g N m–2 y–1) might further enhance the suppression by EMF. In contrast, the presence of EMF consistently increased soil microbial respiration across all nitrogen fertilization levels, indicating that the carbon allocated to EMF could have been largely consumed by microbial respiration and contributed minimally to the accumulation of microbial biomass. Our results also indicated that the suppression of saprotrophs by EMF may play a critical role in driving continuous soil carbon accumulation in this northern pine plantation under atmospheric nitrogen deposition.

Lightweight biodegradable hybrid composite sandwich panel under three‐point bending loads—Experimental and numerical

AbstractIn this research, the flexural behavior of lightweight biodegradable sandwich panel consisting of the outer green composite facesheets with polylactic acid (PLA) matrix and natural kenaf and cotton fibers, with five various stacking types of standard cardboard egg boxes cores under three‐point bending loads as an environmentally friendly alternative to conventional synthetic sandwich structures is investigated. The stiffness of this structure in bending is also studied using finite element simulations. The thickest specimen absorbed the most energy during flexural testing, however, the specimens containing two egg boxes inside each other were found to have a higher strength and stiffness. Using finite element method simulations to investigate the influence of composite facesheet thickness on flexural loads, it was found that the amount of the load carried by each sandwich specimen with doubled thickness was increased at least by about 50%. By changing the core's material from cardboard egg box to bamboo/PLA or kenaf‐cotton/PLA egg boxes, stiffness and strength and also the energy absorption were significantly increased. Therefore, it is possible to fabricate composite sandwich structures which are light and biodegradable for green environment and has the potential to replace many plastic products and structures that are used in food packaging and medium loads structures applications.

Compression and Bending Properties of Short Carbon Fiber Reinforced Polymers Sandwich Structures Produced via Fused Filament Fabrication Process.

Additive manufacturing, through the process of thermoplastic extrusion of filament, allows the manufacture of complex composite sandwich structures in a short time with low costs. This paper presents the design and fabrication by Fused Filament Fabrication (FFF) of composite sandwich structures with short fibers, having three core types C, Z, and H, followed by mechanical performance testing of the structures for compression and bending in three points. Flatwise compression tests and three-point bending have clearly indicated the superior performance of H-core sandwich structures due to dense core structures. The main modes of failure of composite sandwich structures were analyzed microscopically, highlighting core shear buckling in compression tests and face indentation in three-point bending tests. The strength–mass ratio allowed the identification of the structures with the best performances considering the desire to reduce the mass, so: the H-core sandwich structures showed the best results in compression tests and the C-core sandwich structures in three-point bending tests. The feasibility of the FFF process and the three-point bending test of composite wing sections, which will be used on an unmanned aircraft, have also been demonstrated. The finite element analysis showed the distribution of equivalent stresses and reaction forces for the composite wing sections tested for bending, proving to validate the experimental results.

Agia Marina and Peristereònas: Two New Epipalaeolithic Sites on the Island of Lemnos (Greece)

The surveys carried out along the coasts of the island of Lemnos (Greece) have led to the discovery of new Late Epipalaeolithic sites at Agia Marina and Peristereònas. Peristereònas yielded a knapped stone assemblage that is strictly comparable with that from Ouriakos, a site located along the south-eastern coast of the same island, while the artefacts from Agia Marina are more problematic to interpret because they are probably to be attributed to a slightly different period. However, the most characteristic artefacts recovered from the sites are represented by microlithic geometrics obtained by abrupt, bipolar, or direct retouch, end scrapers, and different types of exhausted cores and technical pieces, which help us reconstruct the operational sequence employed for the manufacture of the armatures. The aim of the paper is to contribute to the interpretation of the characteristics of the Late Epipalaeolithic assemblages discovered on the island and to frame them into the general picture of the end of the Pleistocene in this part of the Aegean. The artefacts from the sites show unique characteristics, without parallels to the knapped stone assemblages of the same period so far recovered along the coasts of the Aegean Sea, the eastern Mediterranean, the Levant, and the Black Sea.

Three-point bending performance of sandwich panels with various types of cores

In this paper, the bending performances of sandwich panels with corrugated triangular, honeycomb, aluminum foam, pyramidal truss, double sine corrugated (DSC), and 3D re-entrant auxetic cores are assessed and compared, both experimentally and numerically. Three-point bending experiments were performed on corrugated, honeycomb, aluminum foam, and truss core sandwich panels with identical face-sheets and core height. The experimental and numerical results compared well for panels with corrugated, honeycomb and truss cores. Parametric studies were subsequently performed, using ABAQUS, and three distinct modes of deformation were identified. The specific energy absorption (SEA) of the panels was found to increase with the core relative density; the one with a honeycomb core will be shown to have the greatest SEA, for the same core relative density, compared to the rests.

Integrating Energy-Optimizing Scheduling of Moldable Streaming Tasks with Design Space Exploration for Multiple Core Types on Configurable Platforms

Design space exploration of a configurable, heterogeneous system for a given application with required throughput searches for a combination of cores or softcores with different architectures that can be accommodated within the given ASIC or FPGA area and that achieves the required throughput and optimizes power consumption. For a soft real-time streaming application, modeled as a task graph with internally parallelizable streaming tasks, this requires assigning a core type and quantity and DVFS frequency level to each task, which implies task runtime and energy consumption, and mapping and scheduling the tasks, such that the throughput requirement is met. We tightly integrate such static scheduling for stream processing applications with design space exploration of the best heterogeneous core combination, and solve the resulting combined optimization problem by an integer linear program (ILP). We evaluate our solution for different numbers of core types on synthetic and application-based task graphs, and demonstrate improvements of up to 34.8% for ARM big and LITTLE cores, and 70.5% for 3 different core types.

Fraction distribution and dynamic cycling of phosphorus in lacustrine sediment at Inexpressible Island, Antarctica.

Phosphorus (P) chemistry and its dynamic cycling are essential for understanding aquatic primary productivity and ecosystem structure. However, there is a lack of knowledge on P chemistry in pristine aquatic ecosystems, such as in Antarctica. Here, we applied the Standards, Measurements and Testing Program (SMT) procedure and nuclear magnetic resonance spectroscopy (NMR) to reveal P speciation in two types of lacustrine sediment cores collected from Inexpressible Island, Ross Sea, East Antarctica. The Positive Matrix Factorization Model and Generalized Additive Models were applied to quantitatively identify the P sources and estimate relative effects of various environmental factors on the speciation. Our results demonstrate that orthophosphate, mainly as Ca-P, is the major component and the ortho-monoesters are the predominant organic phosphorus (OP) form in lacustrine sediments. Ornithogenic lacustrine sediments have a higher content of P as Ca-P than sediments with little or no penguin influence. Our model further suggests that penguin guano is the most important source for Ca-P, accounting for 80%, while detrital input is the predominant source for Fe/Al-P (up to 90%). The content of ortho-monoesters, as revealed by NMR, declines with depth, reflecting mineralization process of OP in the sediments. Moreover, we observed higher relative proportions of organic P in the sediments with little guano influence and the deposition of organic P are likely facilitated by microbial mats. Overall, our data suggest that burial of P in Antarctic lakes is sensitive to different P sources and sedimentary environments. The relatively higher bioavailable phosphorus in lacustrine sediments largely controls growth of aquatic microbial mats in oligotrophic lakes and ponds in Antarctica. The sediment profile data also indicate that P burial increased during the Medieval Climate Anomaly period, and climate warming is more conducive to P burial through the expansion of penguin populations and productivity of microbial mats. Our findings represent the first systematic understanding of natural P cycling dynamics and its main controlling factors in pristine ponds with different organic sources in Antarctica.

Influencing Factors of Surfactant Stripping Crude Oil and Spontaneous Imbibition Mechanism of Surfactants in a Tight Reservoir.

Surfactants play a vital role in the working fluid during the exploitation of tight reservoirs. The main goal is to clarify the mechanism of surfactant production enhancement in the reservoir. In this paper, starting from the interface properties and emulsifying properties of surfactants, the factors affecting the stripping of crude oil by different surfactants were described in detail. Meanwhile, the imbibition experiments of cores were used to clarify the two spontaneous imbibition mechanisms of the surfactant. Namely, they are the capillary force expulsion caused by the emulsion stripping thermal diffusion–convection and the wettability change. When the interfacial tension between the surfactant and oil is in the range of 10–2–10–3 mN/m, the particle size of emulsion is less than 1 μm, and the oil stripping efficiency is greater than 58%. The imbibition is mainly caused by thermal diffusion–convection. The wetting angle of the surfactant mainly changing wettability is less than 15°, and the adhesion work is greater than 52 mN/m. Using X-ray computed tomography, the surfactant imbibition distance of different permeability types of cores was obtained. The results show that higher permeability cores have a deeper imbibition distance. The results of this paper enrich the mechanism of enhanced oil recovery by surfactants and have important implications for the exploitation of tight reservoirs.

A comprehensive study on size and definition of the core group in the proven and young algorithm for single-step GBLUP

BackgroundThe algorithm for proven and young (APY) has been suggested as a solution for recursively computing a sparse representation for the inverse of a large genomic relationship matrix (G). In APY, a subset of genotyped individuals is used as the core and the remaining genotyped individuals are used as noncore. Size and definition of the core are relevant research subjects for the application of APY, especially given the ever-increasing number of genotyped individuals.MethodsThe aim of this study was to investigate several core definitions, including the most popular animals (MPA) (i.e., animals with high contributions to the genetic pool), the least popular males (LPM), the least popular females (LPF), a random set (Rnd), animals evenly distributed across genealogical paths (Ped), unrelated individuals (Unrel), or based on within-family selection (Fam), or on decomposition of the gene content matrix (QR). Each definition was evaluated for six core sizes based on prediction accuracy of single-step genomic best linear unbiased prediction (ssGBLUP) with APY. Prediction accuracy of ssGBLUP with the full inverse of G was used as the baseline. The dataset consisted of 357k pedigreed Duroc pigs with 111k pigs with genotypes and ~ 220k phenotypic records.ResultsWhen the core size was equal to the number of largest eigenvalues explaining 50% of the variation of G (n = 160), MPA and Ped core definitions delivered the highest average prediction accuracies (~ 0.41−0.53). As the core size increased to the number of eigenvalues explaining 99% of the variation in G (n = 7320), prediction accuracy was nearly identical for all core types and correlations with genomic estimated breeding values (GEBV) from ssGBLUP with the full inversion of G were greater than 0.99 for all core definitions. Cores that represent all generations, such as Rnd, Ped, Fam, and Unrel, were grouped together in the hierarchical clustering of GEBV.ConclusionsFor small core sizes, the definition of the core matters; however, as the size of the core reaches an optimal value equal to the number of largest eigenvalues explaining 99% of the variation of G, the definition of the core becomes arbitrary.

Investigation of effect of perforations in honeycomb sandwich structure for enhanced blast load mitigation

Sandwich structure is one of the blasts protecting and energy absorbing materials with different types of light weight cores. This article aimed at investigating blast response of hexagonal honeycomb sandwich structure having perforations along the cell height of core over conventional honeycomb cores. The study discussed the mechanics of deformation behavior of perforated sandwich structure to improve the energy absorption characteristics of the bare honeycomb core sandwich structure. Detailed numerical analysis is conducted to accurately produce the deformation process with finite element analysis using explicit software LS-DYNA®. Blast load resulting from 1 kg TNT on the sandwich structure is applied using Conventional Weapons Effects Program (ConWep) function available in LS-DYNA. Several different parameters consisting of varying sizes of perforation by changing d/l ratio, shape, number of perforations and different facesheet and backsheet thicknesses, and different scaled distances are investigated in detail. The results indicated that both size and shape and number of perforations have significant influence on reduction of blast impulse. The variation of facesheet and backsheet thicknesses without changing the overall thickness of the structure also has evident effect in blast resistance capability of perforated honeycomb sandwich structure. The blast mitigation and energy absorption capacity of honeycomb core sandwich structure can be improved with the provision of perforations and optimizing the arrangement of holes. The perforated honeycomb core is further investigated based on analytical formulation developed using single degree of freedom (SDOF) system analysis approach. Optimization study is done further to get the best configuration based on different design variable limits.

Algorithmic definitions of street network centrality sub-shapes: The case of superblocks

The shape and distribution of the most integrated streets, collectively called the integration core, is critical to the characterization of local and global street network types in the space syntax literature. The description of the shape, position, and distribution of integration cores relative to the underlying street networks, however, has remained largely intuitive. We propose analytic and algorithmic definitions of integration core types. We then study empirical and experimental superblock designs with rectangular boundaries, as a particular kind of urban spatial syntax. The analysis leads to a clear understanding of the different ways in which the local street network, internal to the superblock, is structured and interfaced with the perimeter. When used as part of an automated sorting and query process applied to a universe of experimentally generated designs, our definitions and algorithms provide new insights about the interplay between the local generators of street network differentiation and the emergent syntactic structures of the superblock as a whole.