Values Of Physical Properties Research Articles

Dark energy stars with cosmological constant as a black-hole mimickers

In this study, we investigated an interior solution of a static spherically symmetric dark energy star model incorporating anisotropic fluid and a state parameter of the type cosmological constant, achieved through parametrization of the Finch and Skea metric function. The motivation for this study stems from the lack of investigation of dark energy star models in relation to BHs in the previous studies, and from recent proposals suggesting that dark energy might originate inside BHs. This opens up the opportunity to explore the dark energy star model and establish its relationship with BHs. The structural profiles of the models, including mass function, energy density, compactness, surface redshift, and local acceleration due to gravity, were investigated. Analysis involving the matching of the exterior Schwarzschild vacuum solution to the interior spacetime at a junction interface was also explored. The results demonstrate that this solution is free of singularities, possessing outward gravitational repulsion with an infinite property near the surface boundary. Notably, the model exhibited an infinite redshift surface, and a compactness of one half, thus evading the Buchdahl limit. It fulfills the energy conditions except for the strong energy conditions and remains in a state of static equilibrium, upheld by both hydro-static and anisotropic forces. Numerical values of physical properties for various types of astrophysical BH candidates have been determined. Overall, the obtained model is physically unique and represents the most compact and extreme model of dark energy stars. Some features of this model resemble those of BHs, rendering it indistinguishable from BHs.

Characterization of Local Metakaolin Powder for Application as Geopolymer Precursor for Concrete Binder

It is known that metakaolin powder has proved to be a promising alternative concrete binder to Ordinary Portland cement (OPC). Portland cement production contributes about 8% to the global CO2 emission, which is detrimental to the environment and a major contributor to global warming. It is therefore pertinent to develop alternative costeffective and environmentally friendly cement materials. This study examines the performance of a Nigerian metakaolin-based powder as a sustainable material alternative to Portland cement. The Gwaram-Alkaleri Kaolin clay from Bauchi State, Nigeria, was calcined at 800°C for 3 hours as step prior to metakaolin formation. The powder specimens were characterized using XRF, moisture content, specific gravity, density, particle size distribution analysis and specific surface area techniques. Parametric analyses of the values of the specific gravity, density, particle size distribution and specific surface area were undertaken and comparisons and deductions made. The results revealed that Gwaram-Alkaleri metakaolin-powder can serve as a potential sustainable construction material for the Nigerian construction industry because of its availability, affordability, physical and chemical properties values, and significant reduction in CO2 emission, taking cognizance that the results positively indicate that it can be used as an alternative binding powder to cement in concrete and mortar production.

Chemical and Physical Properties of Selected Biochar Types and a Few Application Methods in Agriculture

Biochar, a carbon-rich by-product of organic matter pyrolysis, has a variety of physiochemical properties beside a variety of applications. This review highlights some physical and chemical characteristics of herbaceous, woody, and sewage waste biochar under different pyrolysis conditions, as well as soil and foliar applications of biochar. The controlling role of pyrolysis temperature was the reason for selecting the discussed biochar types in the study. This review concludes that increasing pyrolysis temperature mainly raised the values of some chemical properties of the biochar, such as pH, electrical conductivity (EC), ash content, total phosphorus (TP), and a few values of physical properties like porosity and specific surface area (SSA). On the other hand, yield and total nitrogen (TN) decreased with rising pyrolysis temperature. Among biochar application methods to soil, mixing biochar with soil before planting is one of the best methods of application, and in most cases, biochar reapplication improved soil properties, while foliar application of biochar has positive effects on plant growth and yield parameters, ranging from low rates to the highest ones.

Uso de ultrassom para análise das propriedades de uma haste cobreada de aterramento

The main objective of this work was to use ultrasonic wave values and density to analyze the elastic and physical properties of a copper-plated rod used for grounding. For this, an electronic ultrasound system with 2 MHz piezoelectric transducers and mathematical models that are a function of the propagation speeds of the ultrasonic waves was used. The ultrasonic speeds were determined with the transmission method using petroleum jelly paste as the couplant material. Thus, through the specific equations for isotropic materials, it was possible to estimate some elastic properties, such as modulus of elasticity, shear and compressibility, Poisson coefficient and anisotropy factor, in addition to the physical property of acoustic impedance. The properties of the grounding rod were evaluated before and after a chemical attack with nitric acid to remove the copper layer. As a result, the feasibility of using ultrasound as a non-destructive technique, capable of detecting small changes in the properties of the nail after chemical attack, was verified. The results were compared with the electrical resistivity test and discussed as a function of the values of physical and mechanical properties reported in the literature for the grounding rods.

Learning Effective Good Variables from Physical Data

We assume that a sufficiently large database is available, where a physical property of interest and a number of associated ruling primitive variables or observables are stored. We introduce and test two machine learning approaches to discover possible groups or combinations of primitive variables, regardless of data origin, being it numerical or experimental: the first approach is based on regression models, whereas the second on classification models. The variable group (here referred to as the new effective good variable) can be considered as successfully found when the physical property of interest is characterized by the following effective invariant behavior: in the first method, invariance of the group implies invariance of the property up to a given accuracy; in the other method, upon partition of the physical property values into two or more classes, invariance of the group implies invariance of the class. For the sake of illustration, the two methods are successfully applied to two popular empirical correlations describing the convective heat transfer phenomenon and to the Newton’s law of universal gravitation.

Characterization and damage of the historic brick masonry of the Zákupy castle stables

Abstract A chemical-mineralogical analysis and mechanical tests of historical bricks were carried out as part of the construction-technical survey. The objective was to identify the causes of significant masonry decay. The ruined agricultural yard is a national cultural monument. Conservators believe that the historical importance exceeds that of the neighbouring castle. Stables were designed in 1650 by prominent Italian builders Giulio Broggio and Giovanni Domenico Orsi. The building has not been maintained since the conclusion of World War I. After removal from the masonry, the analyzed samples of bricks reached a very high, almost total degree of water saturation - 87-94%. Some bricks are heavily contaminated with nitrates and sulfates, infrared spectrometry analysis showed that calcium nitrate tetrahydrate is the most abundant of the nitrates. The determined average values of physical properties (bulk weight 1764 kg/m3, capillary absorption 13.6% by weight and open porosity 24% by volume) from samples under atmospheric pressure are comparable to the values of masonry bricks produced today. The results of the tests on the bricks from the Zákupy Castle stables construction demonstrate the high manufacturing quality of the masonry elements utilized. Based on the results of the analyses, it can be assumed that three degradation factors contribute to the observed damage to the bricks: high wetting of the masonry (almost total saturation of pores with water), which is most likely long-term lasting, frost cycles - repeated freezing and thawing of water in the bricks during the winter months, and repeated crystallization of water-soluble salts present in pores near the surface.

Exploring the directly imaged HD 1160 system through spectroscopic characterization and high-cadence variability monitoring

ABSTRACT The time variability and spectra of directly imaged companions provide insight into their physical properties and atmospheric dynamics. We present follow-up R ∼ 40 spectrophotometric monitoring of red companion HD 1160 B at 2.8–4.2 μm using the double-grating 360° vector Apodizing Phase Plate (dgvAPP360) coronagraph and ALES integral field spectrograph on the Large Binocular Telescope Interferometer. We use the recently developed technique of gvAPP-enabled differential spectrophotometry to produce differential light curves for HD 1160 B. We reproduce the previously reported ∼3.2 h periodic variability in archival data, but detect no periodic variability in new observations taken the following night with a similar 3.5 per cent level precision, suggesting rapid evolution in the variability of HD 1160 B. We also extract complementary spectra of HD 1160 B for each night. The two are mostly consistent, but the companion appears fainter on the second night between 3.0–3.2 μm. Fitting models to these spectra produces different values for physical properties depending on the night considered. We find an effective temperature Teff = $2794^{+115}_{-133}$ K on the first night, consistent with the literature, but a cooler Teff = $2279^{+79}_{-157}$ K on the next. We estimate the mass of HD 1160 B to be 16–81 MJup, depending on its age. We also present R = 50 000 high-resolution optical spectroscopy of host star HD 1160 A obtained simultaneously with the PEPSI spectrograph. We reclassify its spectral type to A1 IV-V and measure its projected rotational velocity $\upsilon \sin i$ = $96^{+6}_{-4}$ km s−1. We thus highlight that gvAPP-enabled differential spectrophotometry can achieve repeatable few per cent level precision and does not yet reach a systematic noise floor, suggesting greater precision is achievable with additional data or advanced detrending techniques.

Study on the Physical Properties of Hydrogen-Doped Natural Gas Based on Equation of State

As a zero-emission green clean energy, hydrogen energy is an important means to achieve the strategic goal of carbon neutrality and an important part of the energy Internet. Hydrogen-doped natural gas transportation is an economical and feasible scheme to realize long-distance transportation of hydrogen by using the existing natural gas pipeline network. However, the addition of hydrogen to natural gas will cause obvious changes in the physical properties of the transport medium, which will have a certain impact on the transport characteristics and flow measurement of the pipeline. The main problem is that we need to understand the changes of physical properties after natural gas mixed with hydrogen to ensure the safe operation of natural gas pipe network mixed with hydrogen. Based on this situation, this paper takes BWRS equation as the theoretical basis, selects typical natural gas temperament, calculates and solves the physical parameters of natural gas under different hydrogen blending ratios, and compares them with the standard physical reference values. After verification, the results are used to explore the physical properties of hydrogen-doped natural gas with hydrogen blending ratio, temperature and pressure as variables. The relative average absolute value error (RAAD) of the calculated physical properties of hydrogen-doped natural gas in this paper is less than 2% compared with the reference value of standard physical properties, which can provide theoretical data basis for studying hydrogen-doped pipeline transportation, ensuring pipeline transportation safety and hydrogen-doped natural gas metering.

Restoring soil properties in the Hyrcanian forests from machine induced compaction: Reforestation of N2‐fixing black alder (Alnus glutinosa (L.) Gaertn.)

AbstractAmong the various species of trees, black alder (Alnus glutinosa (L.) Gaertn.) is one of the most commonly used trees for the reforestation and restoration programs of degraded forestlands in the Hyrcanian forest, particularly in the skid trails. The effects of reforestation with black alder on the recovery of litter (thickness, C, N, C/N) and soil physicochemical, biochemical, biological, and microbial properties in the skid trails with three levels of compactions were examined over a 27‐year period. Results showed that the litter characteristics such as thickness, carbon (C), nitrogen (N), and C/N were at the highest level in low intensity traffic as compared to those of medium and frequent intensities. Results showed that the values of total porosity, macroporosity, aggregate stability, silt, and clay were at the lowest level in the natural stand. The highest values of soil pH, C, C/N ratio, and C storage were recorded under the skid trail with frequent machine passages. The restoration values of soil physical and chemical properties were significantly higher in the low level of machine traffic after a period of 27 years where black alder reforestation was performed on the skid trails, as compared to the medium and frequent machine traffic levels, as well as the undisturbed area. Black alder litter affected soil nitrogen and the maximum amounts of earthworm density and dry mass. This also includes fine root biomass. These data were recorded in the trails with low machine traffic as compared to those of medium and frequent traffic. The results clearly showed that black alder is effective in reaching the objectives of restoration programs, given that it promotes soil organic matter, builds up soil structure via root‐soil feedback, and improves the soil by creating a major source of nitrogen through enhancing the nitrogen cycle.

Evaluate the effectiveness of soil and water conservation interventions in the upper Awash Basin, Ethiopia

AbstractThe central highland of Ethiopia is facing significant challenges due to land degradation, which resulted in changes to the soil's physicochemical properties. This study aims to assess the effectiveness of different conservation methods in enhancing soil physicochemical properties, reducing soil loss and erosion, and maximizing land productivity in Ankober District of Kenseta watershed. For this study, two land uses (conserved and non‐conserved land), three slope positions, and three replication with the soil depth of 0–30 cm were used for undisturbed and disturbed soil samples data collection and analysis. The survey data were collected and evaluated from 106 randomly selecting respondents' households. The results showed significant variation in the mean value of soil physical properties (bulk density, soil moisture content, soil texture) within and between conserved and non‐conserved land. The chemical properties, including pH, EC, exK, CEC, OC, OM, and available P, also changed significant across land management types and along slope position (p < 0.05). Soil managed with stone face soil bund demonstrated significant improvement in soil physicochemical properties. The results were statistically significant difference at (p < 0.05) level of significance. Majority of the respondents' households explained the soil loss and rate of soil erosion were declined and land productivity status increased after the adoption of soil and water conservation practices in the study area. Therefore, proper conservation practices are vital in minimizing the rate of soil loss, ameliorating physical and chemical properties of the soils, and enhancing land productivity.

Characterization of goat fiber physical properties from indigenous Ethiopian goat breeds

This study aimed to characterize the physical properties of goat fibers from some indigenous Ethiopian goat breeds. Ethiopia has different indigenous goat breeds, which are the livelihood of Ethiopian farmers and are mainly used as a source of meat, milk, fiber, hides, etc. The fiber samples were collected from Abergelle, Central Highland, and Western Lowland indigenous Ethiopian goat breeds. After shearing, scouring was applied for the removal of some impurities using ionic and non-ionic detergents and chemicals. In this study, fiber length, fineness, tensile strength and elongation, and fiber diameter were evaluated using scientific test-standard methods. The study results showed that the average tensile strengths of goat fibers obtained from Abergelle, Central Highland, and Western Lowland were 13.38, 13.31, and 13.26 cN/Tex, respectively. Similarly, the elongation percentage values were found between 22% and 24% and 32% and 34% in dry and wet conditions, respectively. The moisture regain and moisture content values ranged from 14.04% to 14.10% and 12.61% to 12.68%, respectively. The fiber length values were between 38 and 43 mm, with a diameter ranging from 18 to 21 μm. Even though there was a slight difference in some values of physical properties, the fibers obtained from each goat breed have satisfactory mechanical properties: good strength, fineness, elongation, moisture regain, and low density. Generally, this study proved that the goat fiber obtained from some indigenous Ethiopian goat breeds is a potential source of raw material for textile manufacturers and researchers.

(Invited) Better GaN Substrates Are the Key to Advancing GaN Device Technology

Gallium nitride (GaN) is a semiconductor that has an unusual combination of extreme values of fundamental physical and chemical properties. Its wide bandgap (3.4 eV at room temperature) results in a low intrinsic carrier density and thus low leakage and dark currents. These properties combined with its direct gap are crucial requirements for photo-detectors and high-temperature electronic applications. Despite the relatively large carrier effective masses, which lead to lower carrier mobilities, the high electron saturation velocity and high breakdown field make possible the fabrication of high frequency electronic devices. In addition, its relatively high thermal conductivity opens the possibility to realize a number of high-power device applications. These unique characteristics have made possible the fabrication of a variety of optoelectronic and electronic devices capable of performing at extreme operation conditions of current, voltage, temperature, and in harsh environments. GaN and its alloys and heterostructures with InN and AlN have resulted in devices with superior performance for a variety of applications. Despite this unprecedented and not fully developed semiconductor materials success, the realization of high-performance and high-yield devices will require native GaN substrates with well-controlled physical properties.Presently, Hydride Vapor Phase Epitaxy (HVPE) and Ammonothermal (Ammono-GaN) bulk growth are the only two methods that have successfully demonstrated the manufacture of GaN boules. The first, a fast-growth non-equilibrium process, only reproduces the starting substrate dimensions, while the latter, a slow-growth equilibrium process, allows increasing boule dimensions under controlled growth conditions. Despite the impressive accomplishments recently achieved by these growth methods, much work still needs to be done to establish a fully satisfactory bulk growth method for this material. Heteroepitaxial HVPE-GaN suffers from high dislocation densities, while Ammono-GaN suffers from high oxygen incorporation. Recent results suggest that Ammono-GaN wafers can be successfully used as seeds to grow thick freestanding GaN wafers by HVPE [1]. This approach resulted on HVPE-GaN wafers with orders of magnitude reduced extended defect and lower oxygen impurity concentrations. However, the relatively high background concentration of pervasive impurities is still preventing the realization of high performance devices. In this work, we illustrate how defect-sensitive optical techniques can be used to assist the optimization procedures at various stages of growth [2]. A brief review of defect-sensitive optical spectroscopic techniques employed to evaluate structural, optical, and electronic properties of the state-of-the-art bulk and thick-film (quasi-bulk) Nitride substrates and homoepitaxial films is presented. Defects control the performance of devices and feeding back knowledge of defects to growth efforts is key to advancing technology.References J. A. Freitas, Jr., J.C. Culbertson, N.A. Mahadik, T. Sochacki, M. Iwinska, and M.S. Bockowski, J. Crystal Growth 456 (2016) 113.J. A. Freitas, Jr., J.C. Culbertson, and E. R. Glaser, Crystals, 12 (2022) 1294.

Insights into Properties of Biomass Energy Pellets Made from Mixtures of Woody and Non-Woody Biomass: A Meta-Analysis

There is a widespread global shift toward renewable energy sources, where the emphasis is on enhancing the utilization of renewable energy due to the rising costs associated with fossil fuels. In this light, biomass pellets made from woody and non-woody biomass and blends have gained increased attention. Extensive research has been conducted globally to enhance the quality of biomass pellets and to explore the potential to combine woody biomass with other non-woody forms of biomass in biomass pellet production. The heterogeneity of the raw materials used and resulting properties of the biomass pellets have led to the establishment of internationally recognized benchmarks such as the International Organization for Standardization (ISO) 17225 standard to regulate pellet quality. In this article, the key mechanical, physical, chemical, and energy properties of pellets made of different non-woody herbaceous biomass are investigated, and the available test values for such properties of the pellets were meta-analyzed. A comparison of the properties of these pellets with the relevant standards was also performed. A meta-analysis of studies on biomass pellet production was conducted via a comprehensive Systematic Literature Review (SLR). The SLR focuses on determining and analyzing the average values for the key physical properties of biomass pellets using woody biomass as a component in concert with other biomass materials. In addition, the optimal range of mixtures of woody and non-woody biomass was reviewed to produce biomass pellets with potential acceptance in the marketplace. The majority of studies included in the SLR concentrate on pellets made from a mixture of biomass materials. The results show that the average values for wood/non-wood mixtures such as pellet diameter, pellet length, moisture content, ash content, fine particle content, gross calorific value, and bulk density were found to adhere to the ISO standards. However, the average mechanical durability fell short of meeting the requirements of the standards. Additional comparisons were nitrogen, sulfur, volatile matter, and fixed carbon content. The findings in this meta-analysis could be useful in directing future research focused on producing high-quality and efficient biomass pellets derived from biomass blends and mixtures.

Physical, mechanical, and anatomical properties of 12 jabon (Neolamarckia cadamba) provenances wood in Indonesia

Abstract. Anna N, Siregar IZ, Supriyanto, Sudrajat DJ, Karlinasari L. 2023. Physical, mechanical, and anatomical properties of 12 jabon (Neolamarckia cadamba) provenances wood in Indonesia. Biodiversitas 24: 5895-5904. Jabon is a raw wood material for paper industries and has a fast-growing ability. Comprehensive information on the fundamental qualities of wood from the 12 provenances of jabon (Neolamarckia cadamba (Roxb.) Bosser) is a critical aspect of understanding their superior properties. The age of the samples at the trial was 42 months old, and the number of trees tested was 12, representing one provenance. Wood samples for physical (disk samples), mechanical, and anatomical properties were sampled at a height and length of 1.3 m and 35 cm. The logs were divided into 5 cm and 30 cm for wood samples with anatomical and mechanical properties. The physical and mechanical properties were tested according to ASTM D 4442, ASTM D 2395, and ASTM D 143 standards. The physical (density, specific gravity, and moisture content), mechanical properties (MOE and MOR), and anatomical properties (fiber length and microfibril angle) were carried out on wood from 12 provenances. Physical and anatomical properties were tested, from the pith to the outer bark. The average green wood density was 0.94 gcm-3, while the highest was obtained in the Rimbo Panti, Nusakambangan, Kapuas Tengah, and Batu Hijau provenances. The average specific gravity value from the 12 provenances of jabon was 0.46 in Batu Licin and Batu Hijau provenances; the average moisture content on oven-dry weight was 105.13%; and the highest value was in the Kuala Kencana provenance. The average MOE and MOR values were 51,039.93 kgcm-² and 488.37 kgcm-², with a dry air moisture content of 13.62%. The highest MOE and MOR values were in the Batu Licin and Gowa provenance, with MFA testing varied at 11.54°. The fiber length from the pith to the outer bark tended to increase, with an average of 1183.28 ?m. Based on the value of physical, mechanical, and anatomical properties, 12 provenances of jabon can only be used as non-structural raw materials. The Batu Hijau provenances have the highest density and specific gravity. However, the highest fiber length was found in Gowa provenance.

3-D modeling of automatic pressure gelation process for manufacturing gas insulated switchgear spacer using bio-based epoxy composite

In existing power devices, various insulating parts are manufactured with petroleum-based epoxy resin. However, as petroleum-based resources are gradually depleted and environmental problems have emerged, research on replacing petroleum-based products with eco-friendly materials as insulators has been actively conducted. Therefore, in this study, a molding simulation study of the Auto Pressure Gelation (APG) process, one of the leading technologies, was conducted to manufacture a gas insulated switchgear (GIS) spacer using an environmentally friendly bio-based epoxy composite. Using the heat dissipation and degree of cure obtained through the dynamic differential scanning calorimetry (DSC) test, it was applied to the Kamal-Sourour model which is a representative curing dynamics empirical formula. In addition, the viscosity change during the curing process was measured using a rheometer and applied to the cross Castro-Macoskco model. The results obtained were in good agreement with the experimental values. The parameters calculated above and other physical property values were input into Moldflow software, and simulation was performed targeting the three-phase spacer. While changing the temperature setting of the mold, the change and distribution of flow, temperature, and curing degree inside the product were observed during the reactive molding process. As a result, it was found that there was a possibility of clogging of the mold entrance at some set temperatures, and it was possible to suggest improvement directions to solve this problem. Through this series of research process, it is considered that it will be of great help in improving the quality problems of molded products and the process accordingly.

Density and magnetic susceptibility of major rock types within the Abitibi greenstone belt: a compilation with examples of its use in constraining inversion

Geophysical inversions give non-uniqueness solutions and unless constrained by appropriate initial values and geological constraints can give unrealistic results. One of the critical constraints can be the physical property values of different lithologies. We have compiled a density and magnetic susceptibility database consisting of thousands of measurements collated from different organisations and/or projects across the Abitibi greenstone belt. Statistical tools (histograms, quantile-quantile probability plots and boxplots) are applied to characterise systematically major and minor lithologies. We observed that the magnetic susceptibility frequently has a bimodal distribution, while density is typically unimodal. Our results are summarized in a table that includes the representative mean (or median) and a range of acceptable values. These values can be used to better understand the regional geology, but in this paper, we used the tabulated properties in a geophysical/petrophysical inversion of gravity data from the Chicobi area in the Abitibi subprovince to show the level of improvements that the petrophysical constraints can add to an unconstrained model. When our density database is used to seed the initial guess in a gravity inversion, an anomalous zone becomes apparent that was less evident on an unconstrained inversion.

Study of the Physical Properties and Compressive Strength of Karst Rocks in the Leang Londrong Cave Area Bantimurung Bulusaraung National Park

Research has been carried out on the physical properties and compressive strength of karst rocks in the Leang Londrong cave area. The purpose of this research was to analyzr the value of physical properties and compressive strength of rocks including density and porosity and also calssify limestone types based on the value of physical properties and compressive strength. The compressive strength value obtained from a non-destructive method, namely by using a Schmidt Hammer. The process starts from taking 30 rock samples in the Leang Lonrong cave area at 10 predetermined points. Based on the physical properties test of karst rocks in the Leang Londrong cave area, the rock density values are in the range of 2,60 Â to 2,62 , while the porosity value are in the range 0-6 %. So that the type of rock in the Leang Londrong cave area is dolomite limestone. The compressive strength value of the rock is obtained from the conversion of the Schmidt Hammer rebound value. The value of the compressive strength of karst rocks is obtained in the range of values fro, 20 MPa to 62 MPa. So that the rocks in the Leang Londrong cave area are quite hard or medium types of rock.

Analysis of Mechanical Properties and Structural Analysis According to the Multi-Layered Structure of Polyethylene-Based Self-Reinforced Composites.

In this research, a self-reinforced composite material was manufactured using a single polyethylene material, and this self-reinforced composite material has excellent recyclability and is environmentally friendly compared to composite materials composed of other types of material, such as glass fiber reinforced composites (GFRP) and carbon fiber reinforced composites (CFRP). In this research, the manufactured self-reinforced composite material consists of an outer layer and an inner layer. To manufacture the outer layer, low density polyethylene (LDPE) films were laminated on high density polyethylene (HDPE) fabrics and knitted fabrics, and composite materials were prepared at various temperatures using hot stamping. A 3D printing process was utilized to manufacture the inner layer. After designing a structure with a cross-sectional shape of a triangle, circle, or hexagon, the inner layer structure was manufactured by 3D printing high-density polyethylene material. As an adhesive film for bonding the outer layer and the inner layer, a polyethylene-based self-reinforced composite material was prepared using a low-density polyethylene material. Input data for simulation of self-reinforced composite materials were obtained through tensile property analysis using a universal testing machine (UTM, Shimadzu, Kyoto, Japan), and the physical property values derived as output data and actual experimental values were obtained. As a result of the comparison, the error rate between simulation data and experimental data was 5.4% when the shape of the inner layer of self-reinforced composite material was a hexagon, 3.6% when it was a circle, and 7.8% when a triangular shape showed the highest value. Simulation in a virtual space can reduce the time and cost required for actual research and can be important data for producing high-quality products.

Briquettes Optimization of Palm Shell Waste and LDPE Plastic based on Particle Size and Compressive Strength as Alternative Fuels

The purpose of this study was to find the optimal parameters of the briquette making process (particle size and pressure), where optimization was carried out based on the values of physical properties, namely density, elastic modulus and ultimate tensile strength. The method used in this study was to vary the particle size of palm shell charcoal waste with particle sizes of 40, 60, 80 and 100 mesh mixed with chopped LDPE plastic with a size of 0,5 x 0,5 cm, starch adhesive and water with a predetermined composition, then the briquettes are given varying pressures of 30N/m2, 40N/m2, 50N/m2, 60N/m2, 70N/m2 and 80N/m2. The results of this study found that the highest density value was 808,71 kg/m3, the highest elastic modulus value was 50 MPa, and the highest ultimate strength is 4,81 Mpa. Based on the values of density, elastic modulus and ultimate tensile strength, it can be concluded that the most optimal briquettes are produced from a particle size of 80 mesh and a pressure of 70N/m2 with a density value of 796,08 kg/m3, an elastic modulus of 40 MPa and an ultimate strength of 4,81 MPa.

Post Peat Fire Soil Natural Recovery Based on Physical Properties in South Kalimantan, Indonesia

Indonesia always experiences forest and peatland fires during the extreme dry season. Forest and land fires greatly affect productivity and the environment. The fire was very detrimental to the ecological, economic and social aspects, in addition to the spread of smoke in various countries. This study examines the recovery rate of peat soil after the 2015 fire in the Balangan River - Batangalai River Peat Hydrological Unit (KHG), South Kalimantan. Test results on post-fire land in 2015 after five years (T+5) with a pH value of 2.93; water content is 270.94% and bulk density is 0.225 g cm-3. At (T+7) the test results showed that the pH value was 3.20, the water content was 288.22% and the bulk density was 0.165 g cm-3. Changes in the value of physical properties for five years and seven years after the fire for the pH value increased by 8.60%; the water content value also increased by 5.99% and the bulk density value decreased by 5.99%. Test results on natural (unburn) land in 2015 after five years (T+5) with a pH value of 3.32; water content is 342.60% and bulk density is 0.098 g cm-3. At (T+7) the test results showed that the pH value was 3.43, the water content was 349.94% and the bulk density was 0.082 g cm-3. Changes in the value of physical properties for five years and seven years after the fire for the pH value increased by 3.13%; the value of water content also increased by 2.10% and the value of bulk density decreased by 19.51%. This research is able to indicate that the post fire peat soil naturally become getting close to the unburn condition even though it still in a degraded condition.