Shell Form Research Articles

Different Ice-shell Geometries on Europa and Enceladus due to Their Different Sizes: Impacts of Ocean Heat Transport

On icy worlds, the ice shell and subsurface ocean form a coupled system—heat and salinity flux from the ice shell induced by the ice-thickness gradient drives circulation in the ocean, and in turn, the heat transport by ocean circulation shapes the ice shell. Therefore, understanding the dependence of the efficiency of ocean heat transport (OHT) on orbital parameters may allow us to predict the ice-shell geometry before direct observation is possible, providing useful information for mission design. Inspired by previous works on baroclinic eddies, I first derive scaling laws for the OHT on icy moons, driven by ice topography, and then verify them against high-resolution 3D numerical simulations. Using the scaling laws, I am then able to make predictions for the equilibrium ice-thickness variation knowing that the ice shell should be close to heat balance. The ice shell on small icy moons (e.g., Enceladus) may develop strong thickness variations between the equator and pole driven by the polar-amplified tidal dissipation in the ice; in contrast, the ice shell on large icy moons (e.g., Europa, Ganymede, Callisto, etc.) tends to be flat due to the smoothing effects of the efficient OHT. These predictions are manifested by the different ice-evolution pathways simulated for Enceladus and Europa, considering the ice freezing/melting induced by ice dissipation, conductive heat loss, and OHT as well as the mass redistribution by ice flow.

Resolving species-level diversity of Beringiana and Sinanodonta mussels (Bivalvia: Unionidae) in the Japanese archipelago using genome-wide data

Accurate species identification is of primary importance in ecology and evolutionary biology. For a long time, the unionid mussels Beringiana and Sinanodonta have puzzled researchers trying to unravel their diversity because of their poorly discernible morphologies. A recent study conducted species delineation of unionid mussels based on mitochondrial DNA variation, opening up a new avenue to grasp species diversity of the mussels. However, mtDNA-based classification may not align with species boundaries because mtDNA is prone to introgression and incomplete lineage sorting that cause discordance between species affiliation and gene phylogeny. In this study, we evaluated the validity of the mtDNA-based classification of unionid mussels Beringiana and Sinanodonta in Japan using mitochondrial sequence data, double digest restriction site-associated DNA library (ddRAD) sequencing, and morphological data. We found significant inconsistencies in the mitochondrial and nuclear DNA phylogenies, casting doubt on the reliability of the mtDNA-based classification in this group. In addition, nuclear DNA phylogeny revealed that there are at least two unionid lineages hidden in the mtDNA phylogeny. Although molecular dating technique indicates that Beringiana and Sinanodonta diverged >35 million years ago, their shell morphologies are often indistinguishable. Specifically, morphological analyses exhibited the parallel appearance of nearly identical ball-like shell forms in the two genera in Lake Biwa, which further complicates species identification and the morphological evolution of unionid mussels. Our study adds to a growing body of literature that accurate species identification of unionid mussels is difficult when using morphological characters alone. Although mtDNA-based classification is a simple and convenient way to classify unionid mussels, considerable caution is warranted for its application in ecological and evolutionary studies.

INTRUDUKSI TEKNOLOGI PENGOLAHAN JAGUNG BAGI KELOMPOK WANITA TANI JAGUNG DESA NUNKURUS KECAMATAN KUPANG TIMUR KABUPATEN KUPANG

The Women Farmers Group (KWT) Mardika and Tirosa are a farmer group in Uel Hamlet, Nunkurus Village. Nunkurus Village is located in the East Kupang District, Kupang Regency, located ± 37 km east of Kupang City, has 4 hamlets, 10 RW and RT 20. The population of Nunkurus consists of 755 households (700 farmer households and 55 non-farmer families), with a total population of 3,293 consisting of 1,696 men and 1,595 women. Uel is a hamlet in Nunkurus, where this hamlet has 3 RW and 6 RT, with a total of 145 KK Farmers, the area of ​​dry land in Uel is 670 Ha, of which only 200 ha have been processed, the rest are mixed forest, shrubs and sleeping area. The problem faced by KWT partners Mardika and Tirosa in Uel Hamlet, Nunkurus Village, is how to increase the selling value of corn products which are usually sold in dry shelled form, by processing them to increase the selling value. How to design and build a grinding machine as well as a filter with a certain size and how to maintain good quality of ground corn products. This activity aims to change the product from shelled corn into corn flour and corn rice so that it has a higher selling value. From the results of the application of technology to group partners, namely KWT Mardika and KWT Tirosa, there was an increase in income with the application of the technology provided by 20% of the original income, the technology provided adapted to the business carried out by partners, and produced milled corn products with a size of 100 mesh. , 25 mesh and 6 mesh. The product forms are corn flour, fine grain corn rice and coarse grain corn rice.

Form-finding of shells containing both tension and compression using the Airy stress function

Pure-compression shells have been the central topic in the form-finding of shells. This study investigated tension-compression mixed-type shells by utilizing a NURBS-based isogeometric form-finding approach that analyses Airy stress functions to expand the possible plan geometry. A complete set of smooth version graphic statics tools is provided to support the analyses. The method is validated using examples with known solutions, and a further example demonstrates the possible forms of shells that the proposed method permits. Additionally, a guideline to configure a proper set of boundary conditions is presented through the lens of asymptotic lines of the stress functions.

Modeling and optimization of independent factors influencing lead(II) biosorption from aqueous systems: A statistical approach

Lead, [Pb(II)] is a major hazardous contaminant that exists in the soil, surface, and groundwater as a result of human activities. It is carcinogenic in nature and causes damage to the liver, kidney, and bones as well as the digestive, respiratory, and immune systems. As a result, the main purpose of this study was to prepare and employ modified powdered peanut shells as a biosorbent in the decontamination of lead(II) ions from aqueous solutions. The removal of lead(II) onto the biosorbent was modeled and optimized using the response surface methodology and the effects of three biosorption variables on two response variables were investigated using the central composite design of the response surface methodology. The optimization of lead(II) removal by the biosorbent shows that contact time, pH, and initial concentration had a significant influence on the removal efficiency and biosorption capacity of lead(II). This was shown by the response surface methodology where the interaction among the independent variables studied improved the biosorption of lead(II). Applying the central composite design, the optimized contact time (60.00 min), pH (6.00), and initial concentration (25.00 mg/L) gave a removal of 87.27% and biosorption capacity of 2.87 mg/g of lead(II) with the desirability of 1.00. The study revealed that the modified powdered peanut shells, a low-cost biosorbent was efficient in decontaminating lead(II) ions in the aqueous solutions. However, the biosorption process optimization was dependent on contact time, pH, and initial lead(II) concentration. The study recommends that the untreated form of the peanut shells should be used and the results compared with the present study.

Specimen alignment with limited point-based homology: 3D morphometrics of disparate bivalve shells (Mollusca: Bivalvia).

BackgroundComparative morphology fundamentally relies on the orientation and alignment of specimens. In the era of geometric morphometrics, point-based homologies are commonly deployed to register specimens and their landmarks in a shared coordinate system. However, the number of point-based homologies commonly diminishes with increasing phylogenetic breadth. These situations invite alternative, often conflicting, approaches to alignment. The bivalve shell (Mollusca: Bivalvia) exemplifies a homologous structure with few universally homologous points—only one can be identified across the Class, the shell ‘beak’. Here, we develop an axis-based framework, grounded in the homology of shell features, to orient shells for landmark-based, comparative morphology.MethodsUsing 3D scans of species that span the disparity of shell morphology across the Class, multiple modes of scaling, translation, and rotation were applied to test for differences in shell shape. Point-based homologies were used to define body axes, which were then standardized to facilitate specimen alignment via rotation. Resulting alignments were compared using pairwise distances between specimen shapes as defined by surface semilandmarks.ResultsAnalysis of 45 possible alignment schemes finds general conformity among the shape differences of ‘typical’ equilateral shells, but the shape differences among atypical shells can change considerably, particularly those with distinctive modes of growth. Each alignment corresponds to a hypothesis about the ecological, developmental, or evolutionary basis of morphological differences, but we suggest orientation via the hinge line for many analyses of shell shape across the Class, a formalization of the most common approach to morphometrics of shell form. This axis-based approach to aligning specimens facilitates the comparison of approximately continuous differences in shape among phylogenetically broad and morphologically disparate samples, not only within bivalves but across many other clades.

The signature of large-scale turbulence driving on the structure of the interstellar medium

ABSTRACT The mechanisms that maintain turbulence in the interstellar medium (ISM) are still not identified. This work investigates how we can distinguish between two fundamental driving mechanisms: the accumulated effect of stellar feedback versus the energy injection from galactic scales. We perform a series of numerical simulations describing a stratified star-forming ISM subject to self-consistent stellar feedback. Large-scale external turbulent driving, of various intensities, is added to mimic galactic driving mechanisms. We analyse the resulting column density maps with a technique called Multi-scale non-Gaussian segmentation, which separates the coherent structures and the Gaussian background. This effectively discriminates between the various simulations and is a promising method to understand the ISM structure. In particular, the power spectrum of the coherent structures flattens above 60 pc when turbulence is driven only by stellar feedback. When large-scale driving is applied, the turn-over shifts to larger scales. A systematic comparison with the Large Magellanic Cloud (LMC) is then performed. Only 1 out of 25 regions has a coherent power spectrum that is consistent with the feedback-only simulation. A detailed study of the turn-over scale leads us to conclude that regular stellar feedback is not enough to explain the observed ISM structure on scales larger than 60 pc. Extreme feedback in the form of supergiant shells likely plays an important role but cannot explain all the regions of the LMC. If we assume ISM structure is generated by turbulence, another large-scale driving mechanism is needed to explain the entirety of the observations.

Pemanfaatan Biomassa Padat Kelapa Sawit Sebagai Energi Baru Terbarukan DI PLTU Pabrik Kelapa Sawit PT. Perkebunan Nusantara VI Unit Usaha Bunut

Palm oil is one of the choices of growth companies in Indonesia as biomass energy. Biomass is organic matter made from plants and animals that contain energy. The result of the palm oil processing process is liquid and solid waste.Liquid waste in the form of sludge can be reprocessed into pure palm oil with several treatments.Solid waste in the form of shells and fibers (fibre) derived from palm pulp is used as fuel in boilers and used as steam steam for the process of generating electricity through turbines. Research on the utilization of solid palm oil waste fibers and shells was carried out at PT. Nusantara Plantation VI PKS Bunut because of its large waste potential as an alternative fuel source (renewable energy. Processing capacity of the plant of 30 tons of FFB/hour produces 3.9 tons of fiber solid waste and 2.1 tons of shells, the total solid waste as fuel is 6 tons/hour. The fuel requirement of the plant is 4.55 tons/hour so that there is a difference of 1.45 tons/hour. The electrical energy generated from the utilization of 6 tons/hour of fuel is 776 kW/Hour, while the realization energy used by the factory is 750 kWh/Hour.There is an excess energy of 2.6 kW/hour. This indicates that the use of shells and fibers as fuel for new and renewable energy at the PLTU PKS Bunut PT. Nusantara VI plantations are very good.

The Effect of Microwave Oven Power Variations on Co-Pyrolysis Process of Oil Palm Shells and Polystyrene

Indonesia has a very large area of ​​oil palm plantations, one of which is the island of Sumatra. However, in processing and handling palm oil product waste in the form of palm shells, it has not been maximized. Therefore, the chemical decomposition process can play an important role in supporting waste management and sustainable energy use in Indonesia which is not yet optimal. In this research, the proper use of power will be tested with the help of microwaves as a reactor for the co-pyrolysis process of oil palm shells and polystyrene plastic. The purpose of this study was to determine the appropriate power to produce maximum co-pyrolysis products and to investigate the physical characteristics of the oil-pyrolytic products. The test uses a microwave oven which has a power variation of 300 W, 450 W, 600 W, and 800 W with the addition of a catalyst. The ratio of the composition of oil palm shells to polystyrene plastic is 1:1 with a total mass of 105 gr and using coconut shell charcoal as an activated carbon absorber. The pyrolysis temperature is 500 ℃, the nitrogen gas flow rate is 1.5 LPM, and the pyrolysis time is 60 minutes. Furthermore, testing the physical properties of the pyrolysis oil product in the form of density, acidity, and viscosity testing. The results showed that the optimal power to obtain oil-pyrolytic was 600 W with a product oil of 17.6%, and from the physical properties it had a low viscosity value of 2.55 mPa.s with a pH level of 6.6.

Periodic vibrations of reservoir shell with the real shape imperfections under pressure

The numeral approach to analysis of influence the real shape imperfections on natural and forced periodic vibrations of reservoir shell under pressure was presented. The approach was based on a theory and the methods of structural mechanics and calculable procedures of finite-element software complex NASTRAN. The welded steel reservoir with a variable thickness along its height was investigated. On the manufacted stage, transporting and exploitating the defects of wall shape were formed. The actual radial and angular deviations of the reservoir belts as a result measurements by theodolite were got. Geometry of shell with the real shape imperfections by spline curves and spline surfaces with adding of factual radial and angular rejections to the proper coordinates of points formative shells with an ideal surface was built. Model of reservoir in the form of a cylindrical shell with a three-cornered finite-element net was presented. The limits on the radial and tangential displacements of top edge nodes were entered, the nodes of lower edge were fastened. The periodic loading as external pressure was given. The modal analysis of shell without and with real shape imperfections by the decision of task on natural vibrations (Normal Modes) by the Lanczos method was executed. It was discovered that the natural forms of shell with real shape imperfections had local deformations in the places of maximal radial deviations from a vertical line unlike regular deformations in all natural forms of ideal shell. Natural frequencies were decreased and were slit and there wasn’t influence on its dense distribution due to the presence of shell shape imperfections. A transient and forced periodic vibrations of shell under pressure were investigated. Analysis of transient was executed by the method of direct integration (Direct Transient). The presence of shape imperfections in the shell wall influenced the increase of the transient duration and the dynamic coefficient The direct frequency analysis of shell response on periodic loading (Direct Frequency) was executed taking into account the proper ten first forms and frequencies of natural vibrations. Significant influence of the shell shape imperfections on the resonant frequencies of the forced periodic vibrations and corresponding form of deformation was discovered.

Trends and Opportunities of Bivalve Shells’ Waste Valorization in a Prospect of Circular Blue Bioeconomy

Bivalves aquaculture is already considered a very sustainable for of food production and might become an essential pillar on which to develop future global food security. However, with the increase in production, a correspondingly great amount of waste will be produced all around the earth, principally in the form of shells, which can represent up to 90% of the fresh mollusk weight. Nowadays, shell waste has no notable use and is commonly regarded as waste, often dumped in landfill, or thrown back into the sea, causing a significant level of environmental concern, and resulting in a loss of natural and valuable resources. Bivalve shells are mainly formed by CaCO3, giving them the potential to become a promising secondary raw material for several applications, from a circular economy perspective. This paper aims to review the scientific literature of the last twenty years and the principal recent trends in shell waste reuse, describing applications that are already in place on a large scale in agriculture and livestock, soils, water and wastewater remediation, biodiesel production and biofilters, as well as niche applications that now simply have the potential to be scaled up.

Individualism versus collective movement during travel

Collective movement may emerge if coordinating one’s movement with others produces a greater benefit to oneself than can be achieved alone. Experimentally, the capacity to manoeuvre simulated groups in the wild could enable powerful tests of the impact of collective movement on individual decisions. Yet such experiments are currently lacking due to the inherent difficulty of controlling whole collectives. Here we used a novel technique of experimentally simulating the movement of collectives of social hermit crabs (Coenobita compressus) in the wild. Using large architectural arrays of shells dragged across the beach, we generated synchronous collective movement and systematically varied the simulated collective’s travel direction as well as the context (i.e., danger level). With drone video from above, we then tested whether focal individuals were biased in their movement by the collective. We found that, despite considerable engagement with the collective, individuals’ direction was not significantly biased. Instead, individuals expressed substantial variability across all stimulus directions and contexts. Notably, individuals typically achieved shorter displacements in the presence of the collective versus in the presence of the control stimulus, suggesting an impact of traffic. The absence of a directional bias in individual movement due to the collective suggests that social hermit crabs are individualists, which move with a high level of opportunistic independence, likely thanks to the personal architecture and armour they carry in the form of a protective shell. Future studies can manipulate this level of armour to test its role in autonomy of movement, including the consequences of shell architecture for social decisions. Our novel experimental approach can be used to ask many further questions about how and why collective and individual movement interact.

Effect of Precursor Status on the Transition from Complex to Carbon Shell in a Platinum Core-Carbon Shell Catalyst.

Encapsulating platinum nanoparticles with a carbon shell can increase the stability of core platinum nanoparticles by preventing their dissolution and agglomeration. In this study, the synthesis mechanism of a platinum core–carbon shell catalyst via thermal reduction of a platinum–aniline complex was investigated to determine how the carbon shell forms and identify the key factor determining the properties of the Pt core–carbon shell catalyst. Three catalysts originating from the complexes with different platinum to carbon precursor ratios were synthesized through pyrolysis. Their structural characteristics were examined using various analysis techniques, and their electrochemical activity and stability were evaluated through half-cell and unit-cell tests. The relationship between the nitrogen to platinum ratio and structural characteristics was revealed, and the effects on the electrochemical activity and stability were discussed. The ratio of the carbon precursor to platinum was the decisive factor determining the properties of the platinum core–carbon shell catalyst.

Additive manufacturing of a bridge in situ

AbstractNominated for Eurosteel 2021 Best Paper AwardAdditive manufacturing (AM) is playing an increasing role in the production of complex steel structures. Robot‐ or machine‐guided gas‐shielded metal arc welding (GMAW), known as wire and arc additive manufacturing (WAAM), is suitable for this purpose. A small footbridge was designed in shell form at TU Darmstadt. It was completely additively manufactured over a stream on site using a welding robot. The work called for cantilevered manufacturing without support structures, which poses special challenges in manufacturing. This paper describes selected aspects of this project: the preliminary strength studies, the manufacturing strategy to ensure homogeneous manufacturing and the findings from on‐site manufacturing. In addition, investigations were carried out which led to a notable increase in the deposition rate with the right choice of gas and wire.

Mollusc shell shape as pollution biomarkers: Which is the best biological model?

Alterations in mollusc shells have been proposed contamination biomarkers. We used geometric morphometrics analyses associated with analytical determinations of contaminants to select suitable biological models among species widely distributed on coastal zones. The study was carried out using Lottia subrugosa (herbivore limpet), Crassostrea brasiliana (filter-feeder bivalve), and Stramonita brasiliensis (carnivore gastropod) obtained along a marked contamination gradient at Santos Estuarine System (Brazil). L. subrugosa and S. brasiliensis presented distinct shapes along the gradient, while no significant differences in shell form were seen for C. brasiliana. Indeed, limpets and snails presented morphometric parameters consistent with measured contamination levels hazardous substances. Based on cross-validation models, the reliability of morphometric responses was over 75% for the herbivore and carnivore species. In addition, for S. brasiliensis, a 95.2% confidence was detected in most contaminated sites. Therefore, shell alterations on carnivorous gastropods should be further investigated, seeking to be effectively employed as pollution biomarkers.

Karakteristik Karbon Aktif Tempurung Kluwak (Pangium edule) Sebagai Adsorben Pada Penjerapan Methylene Blue

Kluwak (Pangium edule) is a plant that the seeds are used as a seasoning, to produce waste in the form of kluwak shells that the application has not been widely used by the community. This study aims to utilize the carbonized kluwak shell waste as an adsorbent for the absorption of methylene blue, by activating them using potassium hydroxide (KOH) to increase the adsorption ability of the adsorbent. Variations in the concentrations of KOHused are 0, 1, 3, and 5 M and concentrations of methylene blue solution 100, 110, 120, 130, 140, and 150 ppm. The study reviewed how the characteristics of the kluwak shell as an adsorbent on the absorption of methylene blue, including absorption percentage, maximum adsorption capacity through Langmuir equation, adsorbent morphology through Scanning Electron Microscope (SEM) analysis, and surface area. The adsorption process in this study took place in batches for 90 minutes using a shaker with speed of 300 rpm with volume methylene blue solution as much as 50 mL and the weight of the kluwak shell carbon without activation, and KOH 1, 3, and 5 M activated kluwak shell carbon as much as 0.15 g. The results showed that the higher the concentration of KOH, the higher the average adsorption percentage and maximum adsorption capacity. The amount of the average percent absorption, maximum adsorption capacity, and the largest surface area were on the kluwak shell carbon activated by KOH 5 M, were respectively 97.69%; 48.082mg/g; and 174.17 m2/g. The SEM results analysis showed that activated kluwak shell carbon of 5 M KOH had a larger particle size and pore shape, had a more unified shape, and a flake structure than without activation.

Finite-element modelling, analysis and design of anisogrid composite lattice spoke of an umbrella-type deployable reflector of space antenna

Practical design procedure of a new configuration of anisogrid composite lattice spoke of an umbrella-type deployable reflector of space antenna is presented in the paper. The spoke has a form of long lattice shell with the cross-section made in the form of rounded rectangle. The loads applied to the spoke are generated by the radio-reflective stretched mesh of the deployed reflector. Mass of the spoke is taken as an objective function in the formulated design problem, with constraints imposed on the characteristics of deformability, strength, and stability of the structure. The solution of the problem is based on the results of parametric analyses performed using the finite-element method. The set of design parameters of lattice structure includes the angle orientation of helical ribs, number of helical ribs of one orientation, widths of the helical and hoop ribs, and height of the ribs. A specialised algorithm is developed and applied to the generation of finite-element model for the anisogrid lattice spoke with rectangular cross-section. Using this model, the effects of variations of the parameters of lattice structure on the maximum deflection, maximum stresses in the ribs, and buckling load factor are analysed. Based on the results of these analyses the optimum set of the parameters of lattice structure is identified. At the first stage, feasible values of the structural parameters satisfying the set of constraints are calculated. Then, the optimum combination delivering the minimum value of the spoke mass is determined.

Phylogeny and shell form evolution of the hydrothermal vent asymmetrical barnacles (Cirripedia, Thoracicalcarea, Neoverrucidae)

Imbricaverruca and Neoverruca are two genera of hydrothermal vent asymmetrical barnacles in Neoverrucidae, but found in vents of the Southwest Pacific and Northwest Pacific Oceans, respectively. Imbricaverruca has a flattened operculum and the shell base with multiple whorls of imbricating plates, while Neoverruca has an inclined operculum and the shell base with fewer developed imbricating plates. It has been hypothesized that Imbricaverruca has apomorphic shell characters in Neoverrucidae. Although the monophyletic relationship of the vent barnacle members in the superfamily Neolepadoidea were confirmed based on molecular phylogeny, the relationships between Neobrachylepadidae and Neoverrucidae, and between Neoverruca and Imbricaverruca have not been determined because there are no molecular data on Imbricaverruca. In this study, we sequenced three nuclear (18S rDNA, 28S rDNA, histone 3) and one mitochondrial (CO1) genes of I. yamaguchii from the Southwest Pacific. Our phylogenetic results showed that Neobrahchylepadidae is the sister taxon to Neoverrucidae (Imbricaverruca + Neoverruca), and Imbricaverruca and Neoverruca are monophyletic sister taxa each other, which not supporting the previous hypothesis that Neoverruca is sister to the clade containing Neobrahchylepadidae and Neolepadidae. These implied that the differences in shell forms between Neoverruca and Imbricaverruca are a result of independent divergent evolution in different deep-sea basins.

Design, finite element analysis, fabrication and electroacoustic characterization of transducer arrays from piezoceramics with hollow cylindrical shell form

Electroacoustic transducers arrays operating in the 50–100 kHz frequency range are currently being investigated for underwater applications such as target detection transducers installed on underwater autonomous vehicles (UAV) and detection of underwater intruders to protect and secure economically and strategically critical coastal areas and facilities. However, the frequency range is such that it prevents the use of monolithic piezoceramics operating in the thickness mode due to the unacceptably high voltages that are required to drive them. Whereas the alternative such as Langevin-type transducer solutions have certain other assembly difficulties that arise due to the size limitations imposed on the transducer from the half-wavelength (λ/2) arrangement requirement of the units. In our study, an entirely new alternative was proposed to overcome these difficulties. A piezoceramic transducer constructed from a hollow cylindrical shell form poled in the radial direction was designed and developed to operate at the longitudinal length extension mode. Since the hollow cylindrical piezoceramics were designed and produced with one end closed, this closed end was used as a passive cap with the transducer operating in a piston mode. ATILA finite element analysis code was used to design, analyze and fine-tune the dimensional requirements of the transducer. The center frequency of the transducer was fixed to 70 kHz. Commercial lead zirconate titanate (PZT) composition with hard piezoelectric character (PZT-4) was used as the starting powder. The slip casting method was used to obtain the cylindrical shell form. Single element transducers, as well as a hexagonal close-packed array consisting of seven units and arranged with a distance of half-wavelength (λ/2) to obtain constructive interference at 70 kHz were constructed and tested for underwater electroacoustic performance.

Experimental and analytical study on coconut in filled concrete blocks

Homelessness in India has been a problem for centuries and it is very essential to the engineering community to rehabilitate the people’s economic and social state in a safe manner. Further the scarcity of natural resources, alarms to invent alternate technologies to overcome the related issues. In particular, the clay bricks are developed from high fertile clay which is important for the cultivation and the process of burning requires wood for firing which become the adverse effect on the environment and societal development. This creates the ecological imbalance which necessitates for developing innovative technologies to utilize the wastes by-product from the industry and the renewable natural resources. Also, the demand for lightweight stabilized soilconcrete blocks for load bearing and non-load bearing walls are increasing rapidly. In view of this, the present study attempted to develop a technology to utilize the waste coconut inner portion for the construction. The coconut inner portion has its own advantageous in the form of shell and the present study performed to explore its effectiveness for the development of light weight concrete blocks. A pair of bare hemispherical coconut shells are kept together to form a closed shell and infilled in to the concrete blocks. The coconut infilled blocks have been casted, cured and tested under compression at 7th, 14th and 28th day. A nonlinear finite element analysis is carried out for the comparison. Both material and geometrical nonlinearity were included in the nonlinear analysis. The analytical results were compared with the experimental result. The maximum load carrying capacity, displacement, strain was determined and compared. The results were seeming to be comparable and the results indicates that the shell action of coconut shell influences the behaviour of light weight concrete blocks.