Board Materials Research Articles

3.5 GHZ VIVALDI ANTENNAS: A COMPREHENSIVE PARAMETRIC ANALYSIS FOR UNLEASHING 5G COMMUNICATION TECHNOLOGY

In this study, we discuss the design and testing of a Vivaldi antenna operating at 3.5 GHz, which is well-suited for mobile mid-band 5G connection. CST Microwave Studio software was used to simulate and evaluate the suggested antenna design, which was printed utilising state-of-the-art 3D printing processes and materials (polylactic acid (PLA) and FR-4 circuit board material). The measured results show that the antenna has a reflection frequency of 3.51 GHz and a gain of -23.695 dB. Parametric analysis was carried out to examine the relationship between antenna performance and design parameters, with special focus on the separation between the antenna and the PLA material in the middle of the spherical construction. The Vivaldi antenna is an attractive choice for 5G mid-band applications because of its wideband features, ease of manufacture using typical industrial processes, and simplicity of impedance matching to the feeding line using microstrip line modelling.

SOLVING THE PROBLEM OF THE WHITENESS OF WEALTH

Peggy McIntosh details “white privilege” 1as including: being in the company of people of her own race; renting or purchasing affordable housing in a desirable area; having pleasant neighbors; shopping alone without being harassed or followed; and turning on the TV or opening the newspaper to see heavy representation of people of her own race. 2 The history of slavery is one major source of wealth disparity: four generations ago, African-Americans were a form of wealth as slaves and even before that, Africans in Africa were seen as primitive. The socioeconomic disadvantages to African-Americans and finding solutions to this problem, especially solutions through funding HBCU’s, targeted debt relief, and increased Black representation in the media, are the aims of this paper on the black-white wealth gap. The average per capita wealth of White Americans was $338,093 in 2019 but only $60,126 for Black Americans. 3 On average between 1950 and 2010, Black households held about 7 percent of their wealth in stock equity; among White households, it was 18 percent. According to the 2016 General Social Survey, a 55% majority of white Republicans agree with the statement that black Americans are worse off financially “because most just don’t have the motivation or willpower to pull themselves up out of poverty.” 4 42% of white Republicans thought black Americans were lazier than white Americans and 26% rated black Americans as less intelligent. 5 The history of the black-white wealth gap is entrenched in slavery and its after-effects. These effects include the Jim Crow rules, the sharecropping landownership system, discrimination, Congress passing unfair tax laws, the tenfold wealth gap, and attempts to fix it with affirmative action. One solution is the benefit of educating black students at historically black colleges and universities such as Howard, Morehouse, and Spelman: Wealthy philanthropists like Mackenzie Scott, the ex-wife of Jeff Bezos, making massive donations to HBCU’s so that Black universities can offer more scholarships to deserving Black students. Robert Smith, the wealthiest black man in the United States, promised to pay off the debts of the Morehouse College class of 2019. Therefore, enabling black students to afford college and allowing them to face fewer obstacles to graduating college are worthwhile, positive aspects of the HBCUs. The best solution to the black-white wealth gap is targeted debt relief, as opposed to blanket debt relief. Scholars argue for increasing Pell Grants so that they cover tuition, room, board and course materials to help more Blacks graduate debt-free. 6 Black students have less access to generational wealth and are the most likely to rely on debt to finance their educations. In this way, targeted debt relief would dramatically help Black students and college graduates. Another solution is more favorable representation of Blacks in the media. Stuart Hall argued that the solution to negative representations of Blacks were favorable portrayals of Blacks.

Low-temperature calcination composite binder from dolomite and its application to facing board materials

The article presents the research to obtain low-temperature calcination binder from dolomitic limestone with a MgO content of less than 20%. The initial dolomite material was calcinated at the following temperature range from 700 to 800 ℃ and firing time 25–45 min. The result of the selection of the optimal firing conditions is semi-calcination product caustic dolomite with a minimum content of residual Mg(CO3)2 and free CaO with bending strength 10–11 MPa. Physical-mechanical characteristics and mineral composition of samples were determined by the use of differential thermal analysis and infrared spectroscopy studies. Preliminary experimental samples of facing composite board materials were prepared and the main physico-chemical parameters were determined: bending strength 4–7.6 MPa, density 800–1400 kg/m3 and water absorption 10–25%. A three-dimensional model for the production of glass dolomite slabs has been developed.

PERBANDINGAN MATERIAL AKUSTIK DALAM MENYERAP BUNYI

This study aims to examine the comparison of room acoustics by using room engineering methods and testing zinc plate and GRC board materials in the same room. The results of the study show that the selection of materials for sound absorption in the room must be considered carefully and adjusted to the desired sound absorption needs. In testing using the room engineering method, it was seen that there was an increase in the effectiveness of sound absorption in both materials at various volume levels. However, in testing using the mandatory sound of the room acoustic tester, it can be seen that the sound frequency at the lower speaker position is more prominent in both materials at a lower volume. Meanwhile, in the test using the free sound of people giving speeches, it was seen that there was an increase in sound frequency at the top speaker position for both materials at a higher volume.

Cutting Boards: An Overlooked Source of Microplastics in Human Food?

Plastic cutting boards are a potentially significant source of microplastics in human food. Thus, we investigated the impact of chopping styles and board materials on microplastics released during chopping. As chopping progressed, the effects of chopping styles on microplastic release became evident. The mass and number of microplastics released from polypropylene chopping boards were greater than polyethylene by 5-60% and 14-71%, respectively. Chopping on polyethylene boards was associated with a greater release of microplastics with a vegetable (i.e., carrots) than chopping without carrots. Microplastics showed a broad, bottom-skewed normal distribution, dominated by <100 μm spherical-shaped microplastics. Based on our assumptions, we estimated a per-person annual exposure of 7.4-50.7 g of microplastics from a polyethylene chopping board and 49.5 g of microplastics from a polypropylene chopping board. We further estimated that a person could be exposed to 14.5 to 71.9 million polyethylene microplastics annually, compared to 79.4 million polypropylene microplastics from chopping boards. The preliminary toxicity study of the polyethylene microplastics did not show adverse effects on the viability of mouse fibroblast cells for 72 h. This study identifies plastic chopping boards as a substantial source of microplastics in human food, which requires careful attention.

An elegant method of book board reattachment

One of the most common types of damage to books is when the boards detach from the bookblock. Consequently, book binders and conservators have been creating ways to reattach boards for decades. This article will briefly examine some of these attachment methods and how they informed, but failed to address, some of the board reattachment problems commonly encountered. It then presents a reattachment treatment that requires minimal intervention to the original spine or board materials but still provides a secure means to attach the boards without compromising the integrity of the sewing structure and allows the volume to be fit for purpose. The treatment is efficient, safe and uses readily available equipment, making it ideal for conservators in private practice and those working with time and cost restraints. The article details step-by-step the novel technique that the author developed to address these issues.

Coupled hygrothermal and mechanical simulations of highly anisotropic building material during freezing and thawing

Porous building materials, such as board materials, wood, stones, fired clay materials, and bio-based materials, often have anisotropic properties. This study investigates adequate numerical models for the coupled hygrothermal and mechanical behaviors of strongly anisotropic building materials during freezing and thawing. First, strain measurements are reported for two types of fired clay materials to confirm the anisotropy of deformation during freezing and thawing. In calculations, the anisotropy of the Biot coefficient of a material is considered based on anisotropic poroelasticity. The comparison between the measurements and calculations revealed that the anisotropic deformation during the measurement cannot be reproduced without considering the anisotropies of the Biot coefficient as well as those of the mechanical properties. In addition, analysis of the causes of the deformation reveals that the expansion in the direction normal to the material thickness due to the water pressure development during the freezing is suppressed by the small Biot coefficient. These results indicate that the anisotropy of the Biot coefficient significantly influence the deformation due to frost actions; consequently, the anisotropic Biot coefficient should be adequately considered in numerical simulations.

Acoustic Design for Urban Educational Buildings by Using Noise Tools, IBANA Calc and Ecotect

Classroom is an integral part of learning activities in educational buildings. Learning in the classroom can be effective and focused if it has a good acoustic design. Unfortunately, most educational buildings are spread out in urban areas, which have a high noise level. This research aims to find the best acoustic design for educational buildings in urban areas. By using Noise Tools, IBANA Calc and Ecotect as simulation method, the research discusses the handling of acoustic design for educational buildings in urban areas through 3 (three) things. (1) Providing a barrier with a height of 2.5 m can reduce noise in the outdoor area of the building from 47.5 to 60.9 dB; (2) The use of block concreates materials, glass laminated and metal panels on the facade of the building, reducing noise to a level of 27dB; (3) The use of framed plaster board and suspended ceiling materials, providing an acoustic response with an estimated decay at all frequencies under 3 seconds.

The Usage of Dried Breadfruit Leaves as Particle Board Material

Breadfruit plant also known as Artocarpus altilis, is a plant that lives in tropical climate. This plant has various advantages neither for consumption nor health. This makes some people interested in growing breadfruit plants. However, most people still do not know breadfruit leaves can be beneficial, so it often ends up as organic waste or compost. From the problem that has been mentioned, dried breadfruit leaves have the potential to be used for other things such as particle board material. Particle board is made from wood chips and adhesive such as resin that are processed at high temperature also pressed until it become a board. The theory and method that are used in these experiments is quantitative to know whether dried breadfruit leaves have a good quality as particle board material or not. The experiments use different variables and will be compared to determine which experiments have the best quality. With this experiments method, the expected result is that dried breadfruit leaves can be used as particle board material with a good strength and density.

Characterization studies on calcium silicate boards and fibre cement boards used as sheathing in light gauge steel framed systems

This paper presents a systematic mechanical characterization study on two types of board materials reinforced with lignocellulosic fibres used as sheathing in light gauge steel framed building, namely calcium silicate board (CSB), and fibre cement board (FCB), under tensile, compressive and shear loading. The ASTM and EN standards for wood-based panels recommend the preparation of the test specimen by bonding additional numbers of boards along thickness to eliminate global buckling under compression and shear loading. However, it is observed that the FCB and CSB specimens still suffers premature bearing failure at the loaded ends and delamination of the boards at the glued interface which often fails to characterize the actual material behaviour. To overcome this limitation, the paper proposes a unified coupon made of single (virgin) thick board and the use of combined loading compression fixtures and large panel–shear test fixtures to simulate the desired failure modes and obtain complete stress–strain response under compression and shear loading, respectively. The scope of the work majorly encompassed an extensive experimental program comprising of total 115 specimens made of FCB and CSB of thicknesses 8 mm, 10 mm and 12 mm, tested along both longitudinal and transverse directions to evaluate the constitutive properties and strength limit states. The results show that the FCB exhibits higher strength and stiffness than the CSB specimens. Further, a nonlinear stress–strain model was established to represent the response of the board material under compression.

Development of glue-free composite material based on plant raw materials

Objects of research: composite materials obtained by chemical modification of the plant base using glueless technology in the sintering process.&#x0D; Purpose of research: to develop a method for obtaining board materials based on plant raw materials with increased mechanical strength characteristics and exploitative properties.&#x0D; Methods of research: by hot press molding technology in the presence of crosslinking chemicals (urea, benzylchloride, basic cupric carbonate) were obtained board materials with high fracture strength and increased fire safety.&#x0D; Main results of research: obtained materials can be used for construction purposes and as a replacement for flakeboard and fiberboard.

Technological Trends in High-Frequency Low-Loss Printed Wiring Board Materials for Information and Communication Systems

Technological Trends in High-Frequency Low-Loss Printed Wiring Board Materials for Information and Communication Systems

ИЗУЧЕНИЕ ЗАВИСИМОСТИ ЭКСПЛУАТАЦИОННЫХ СВОЙСТВ ПЛИТНЫХ МАТЕРИАЛОВ НА ОСНОВЕ ДРЕВЕСИНЫ ЛИСТВЕННИЦЫ ОТ УСЛОВИЙ ПРЕССОВАНИЯ

The integrated use of raw wood materials in mechanical and chemical processing is a rather complex process: there are such wastes as bark, wood chips, lignocellulosic masses, and lignosulfonates. They can be disposed of with a positive economic effect. We consider the possibility of obtaining board materials directly from larch wood production waste using hydrothermal treatment without carcinogenic binders. The research examined the influence of pressing conditions, particularly pressure and temperature, on the properties of board materials and determined the optimal conditions for this process. We conducted a comparative analysis of the properties (strength and hydrophobic nature) of the obtained board materials with the industrial analogs.

Experimental studies on fiber cement boards under compression loading

Fibre cement boards are widely used as external cladding in cold-formed steel (CFS) building systems, due to their superior durability and weather-resistant characteristics. These boards are made of cement and reinforced with short, randomly oriented, non-hazardous cellulose fibres. Characterizing the observed stress-strain behaviour of the board under compression loading is a challenging task due to: a) loading eccentricity which induces bending, b) global buckling caused by high slenderness of the specimen, and c) stress concentrations at the loading end resulting in bearing failure. The above failures are usually handled at the specimen preparation stage by gluing additional numbers of boards to reduce slenderness, and by the inclusion of end tabs to avoid bearing failure. However, the introduction of glue in the board specimen may alter the strength characteristics and modify the load transfer path. Preliminary studies on the board specimens following the standard testing procedure (ASTM D3501) for wood-based panels fail to simulate the real material behaviour of the boards under compression loading. It is clear that the existing test methods have several shortcomings and hence cannot be adopted for fibre cement boards. In this paper, the fibre cement boards were tested under compression loading using combined loading compression (CLC) test fixture. This paper presents the details of the experimental study and the results for board of thicknesses 8, 10, and 12 mm, respectively. The test matrix includes specimens tested in both longitudinal and transverse directions. Under compression loading, the board exhibited nonlinear behaviour up to failure. The structural parameters like ultimate stress, ultimate strain, Young's modulus, and Poisson ratio in both longitudinal and transverse directions were obtained. This study proposes a nonlinear constitutive model for the board material.

Analysis of the effect of heating rate on pyrolysis kinetics and product composition of copper-containing waste circuit boards.

Pyrolysis is a cost-effective and environmentally benign method for recycling organic waste, which can be converted into high-energy gases and oils. Pyrolysis technology was employed in this study to recycle copper-containing discarded circuit board material and recover copper, glass fibers, and gases and oils with high calorific values. Thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FTIR), and gas chromatography-mass spectrometry (GC-MS) were used to evaluate pyrolyses of copper-containing waste circuit board materials conducted at different heating rates (5, 10, 20, and 40°C/min), and the resulting volatiles were studied in detail. The effects of heating rate on the kinetics and activation energies for pyrolyses of copper-containing waste circuit boards were also investigated by using the Coats-Redfern (C-R) method. The TGA curves and FTIR spectra did not differ significantly for different heating rates, and the main functional groups identified with the FTIR results were O-H, C = C, aromatic benzene, substituted benzene, and C-Br. Additionally, GC-MS analyses showed that the heating rate had a great influence on the pyrolysis products formed; the phenol content decreased with increasing heating rate, and the highest content was realized at 5 ℃/min. Energy dispersive spectroscopy (EDS) analyses showed that bromine was removed from the solid phase products during pyrolysis, while copper was effectively enriched in the feedstock. This indicated that pyrolysis can be used to recover copper-containing waste circuit boards.

Agricultural Development: The Role Of Government in Agricultural Development (Article Review)

Agricultural development is a process aimed at continuously increasing agricultural production in order to increase agricultural production for each consumer, which at the same time increases the income and business productivity of each farmer by increasing capital and skills to increase human involvement in the development of crops. plants and animals. Agricultural development is an integral part of economic development and society in general. Broadly speaking, agricultural development is not just a process or activity to increase agricultural production but is a process that produces social changes in values, norms, behavior, institutions, social and so on in order to achieve economic growth and improve the welfare of farmers and society. Agriculture is the main sector producing food ingredients and industrial materials that can be processed into clothing, food, and board materials that can be consumed or traded, therefore agricultural development is part of economic development.

Послойный динамический модуль сдвига в поперечном сечении древесностружечной плиты

The research results are aimed at the formation of ideas concerning the features of molecular motion of the components of the outer and inner layers of the particle board material in the temperature range from room temperature to 275–300 °C, as well as at revealing the fact of binder undercuring in the inner layers. The paper provides data on the temperature dependences of the dynamic shear modulus of the outer and inner layers of the particle board material, obtained by dynamic mechanical analysis using a torsion pendulum. We found significant differences in the nature of the dependencies for samples taken at different distances from the surface layers. The material of the outer layers is characterized by the typical pattern of a continuous irregularly consistent decrease in the dynamic shear modulus with increasing temperature, which is common to most polymeric and composite materials. A short-term intermittent increase in the dynamic shear modulus relative to neighboring areas was detected in the inner layers at 140±5 °C, which is not typical for materials in a stable state. There is also a tendency for the dynamic shear modulus of the particle board material to decrease at room temperature with distance from the outer layers, due to the heterogeneous fractional composition and differences in the nature of chemical cross-linking during hot pressing. It has been assumed that the detected anomalous increase in the dynamic shear modulus in the inner layers of the material at 140±5 °С is a symptom of the binder post-treatment process directly in conditions of its heating when measuring the dynamic shear modulus by dynamic mechanical analysis. Thus, it is concluded that the particle board sample shows maximum curing of the thermosetting binder in the layers, which are 4.5–5.0 mm distant from both surfaces. Partial undercuring of the binder occurs in the inner layers, which are more than 5.5 mm away from the surfaces. Thus, it is shown that the method of dynamic mechanical analysis can be used as a tool to control the presence in the inner layers of the particle board material of the components of thermosetting binder, undercured in the hot pressing process, which will help to obtain a material with more stable characteristics.

Design of a Compact ISM-band Microstrip Slot Antenna for Wireless Sensor Nodes

Objective: To enhance the design and implementation of microstrip antenna for wireless Sensor Networks (WSN) in real-time applications Methods: This study uses radio communication to connect end nodes and forms a multihop self-organizing network with a dynamic topology. Also, the antenna is fabricated from low-cost FR-4 printed circuit board (PCB) material. The designed rectangular patch antenna operates in the industrial, scientific, and medical (ISM) frequency band of 2.45 GHz, and HFSS software analyzer is used to authenticate the proposed work. Findings: The designed antenna finds an extensive use in short-range wireless sensor networks, the proposed antenna reduces the return loss from 10% - 13 % and almost 15% improvement in radiation compared with K. D. Xu (2018) and E. Zhang (2020). Novelty: A novel short range, low power, and well directional microstrip patch antenna are designed to improve the wireless Sensor communication applications operating at 2.4 GHz and 5.3 GHz frequencies. The presented approach is simple to operate, cost-effective, energy-efficient, and has optimum return loss performance (please refer Table 2) when compared to the existing approaches. Keywords: Microstrip antenna; Compact; HFSS; Wireless Sensor Network; dual frequency

A Deployable and Cost-Effective Kirigami Antenna for Sub-6 GHz MIMO Applications.

In this work, a low-cost, deployable, integratable, and easy-to-fabricate multiple-input multiple-output (MIMO) Kirigami antenna is proposed for sub-6 GHz applications. The proposed MIMO antenna is inspired by Kirigami art, which consists of four radiating and parasitic elements. The radiating and parasitic elements are composed of a rectangular stub. These elements are placed in such a way that they can provide polarization diversity. The proposed MIMO antenna is designed and fabricated using a soft printed board material called flexible copper-clad laminate (FCCL). It is observed from the results that the proposed MIMO antenna resonates in the 2.5 GHz frequency band, with a 10 dB reflection coefficient bandwidth of 860 MHz ranging from 2.19 to 3.05 GHz. It is worthwhile to mention that the isolation between adjacent radiating elements is higher than 15 dB. In addition, the peak realized gain of the MIMO antenna is around 11 dBi, and the total efficiency is more than 90% within the band of interest. Moreover, the envelope correlation coefficient (ECC) is noted to be less than 0.003, and the channel capacity is ≥17 bps/Hz. To verify the simulated results, a prototype was fabricated, and excellent agreement between the measured and computed results was observed. By observing the performance attributes of the proposed design, it can be said that there are many applications in which this antenna can be adopted. Because of its low profile, it can be used in 5G small-cell mobile MIMO base stations, autonomous light mobility vehicles, and other applications.

Effect of Terrestrial Laser Scanning (TLS) parameters on the accuracy of crack measurement in building materials

Terrestrial Laser Scanners (TLS) have gained momentum in identifying cracks and deformations. Although TLS efficiency has been recognized over time, the scan data quality is contingent upon various parameters (e.g., material type and scan settings), which impacts the use of TLS. To address this barrier, this study investigates the measurement accuracy in the context of crack analysis in foam board and common building materials (concrete, wood, and masonry) by conducting a set of controlled experiments with different scan settings (e.g., scan distance and angle of incidence). The findings of this study provide practical contributions to using TLS for crack identification, specifically addressing the effect of different parameters on point cloud data quality and proposing boundary ranges for different scan settings regarding different building materials and crack widths to facilitate TLS planning.