ARTICLE | doi:10.20944/preprints202201.0104.v1
Subject: Social Sciences, Psychology Keywords: state IQ; aggregate IQ; well-being; g nexus; PIAAC; NAEP
Online: 10 January 2022 (12:05:43 CET)
At the level of the 50 U.S. states, an interconnected nexus of well-being variables exists. These variables have been shown to strongly correlate with estimates of state IQ in interesting ways. But the state IQ estimates (McDaniel 2006) are now more than 16 years old, and the state well-being estimates (Pesta et al., 2010) are over 12 years old. Updated state IQ and well-being estimates are therefore needed. I thus first created new state IQ estimates by analyzing scores from both the Program for the International Assessment of Adult Competency (for adults), and the National Assessment of Educational Progress (for fourth and eighth grade children) exams. I also created new global well-being scores by analyzing state variables from the following four well-being subdomains: crime, income, health, and education. When validating the nexus, several interesting correlations existed among the variables. For example, state IQ most strongly predicted FICO credit scores, alcohol consumption (directly), income inequality, and state temperature. Interestingly, state IQ derived here also correlated .58 with state IQ estimates from over 100 years ago. Global well-being likewise correlated with many old and new variables in the nexus, including a correlation of .80 with IQ. In sum, at the level of the U.S. state, a nexus of important, strongly correlated variables exists. These variables comprise well-being, and state IQ is a central node in this network.
ARTICLE | doi:10.20944/preprints202004.0451.v1
Subject: Engineering, Civil Engineering Keywords: Construction and Demolition Waste; recycled aggregate; structural concrete; absorption coefficient; graded aggregate; soil, base layer
Online: 24 April 2020 (14:20:23 CEST)
Construction and demolition waste (CDW) represents 1/3 of the weight of all-waste produced. Increasing their recycling and reutilization with recycled aggregates (RA) means closing the life cycle of construction materials. Research has been carried out on artificial aggregates from the exclusive crushing of structural concrete waste in selective demolitions (CDWRConc). This study analyses the use of recycled concrete as graded aggregate (GARConc) and in cement soil (CSRConc). The material complies with the requirements as a road base, although due to the low values of resistance to fragmentation these materials are adequate for use in sensitive road systems and other places such as urban roads and car parks. The sensitive road systems are infrastructures in places of great natural wealth and low traffic intensity, with an annual average of heavy vehicle traffic (AADTh) below 50 vhp/d. As soluble salt contents have been detected, additional waterproofing or drainage measures must be adopted to prevent water infiltration into the layers made up of CDWRHorm. Finally, the high initial values of UCS allow the temporary passage of light vehicles over CSRConc after 3 days.
ARTICLE | doi:10.20944/preprints202303.0541.v1
Subject: Engineering, Civil Engineering Keywords: EPS; Interface; Lightweight aggregate; Hydration products
Online: 31 March 2023 (03:38:56 CEST)
To improve the interfacial compatibility between cement matrix and expanded polystyrene (EPS) in the core-shell lightweight aggregates (CSLA), the effects of sodium silicate, Polyvinyl alcohol (PVA) emulsion, Vinyl acetate-ethylene (VAE) emulsion, acrylic acid, and acetic acid on the cement-EPS interface were investigated. The denseness of the interface was studied by scanning electron microscopy (SEM), and the effect of interfacial agents on the hydration process of cement was studied by the heat of hydration and induction resistivity. The macroscopic properties of the interface of the CSLA were characterized by the "leak-white" rate, drop resistance and numerical crushing strength. The results show that the sodium silicate densifies the interface by generating hydration products on the EPS surface. At the same time, organic acid enhances the interfacial properties of EPS and cement by increasing the surface roughness and allowing hydration products to grow in the surface micropores. In terms of the cement hydration process, both two interfacial agents delay the cement hydration. Above all, with comprehensive interface properties, "leak-white" rate, and mechanical properties, VAE emulsion and sodium silicate can achieve the best performance with a final crushing resistance of 5.7 MPa.
ARTICLE | doi:10.20944/preprints201910.0022.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: North Wales; slate mining industry; slate aggregate; secondary aggregate; transportation cost; low quality waste material; physical and chemical properties
Online: 2 October 2019 (06:28:03 CEST)
The slate aggregate has long been perceived as a substandard, low quality waste material with its physical and chemical properties not being competitive with those of the primary aggregates. It is assumed that the slate aggregate particles are not strong, that is not durable and will not compact. This research aims to address those claims and review the available literature on the performance of the slate aggregate. The review inaugurates by analysing the physical, chemical and mechanical properties of slate, before expanding into a literature review of laboratory testing’s on the effect of moisture content on density, compaction and layer thickness of slate aggregate.The paper reviews case studies of construction projects in North Wales, where the slate aggregate has been used for general fill and road building for many years. Some of the case studies include the A55 coastal road and duelling of the A5 in Anglesey (WRAP, 2004), where slate aggregate was successfully used as sub-base. The paper also investigates why many civil engineers are reluctant to use the slate aggregate and regard the material as sub-standard, flaky aggregate. The research paper reviews the potential usages and various products the slate aggregate is suitable for and satisfies the requested standards. The final topic reviewed is the cost of transporting slate aggregate compared with the cost of transport for primary aggregate and the introduction of the Primary Aggregates Tax (Parliament of the United Kingdom, 2011). The last topic includes a critical analyses of the claims that the slate aggregate a commercially viable construction material despite its remote location (Woodward et al, 2004). The transportation cost and the supply chain complexities must be evaluated prior to considering the long-term sustainability of the product (Radanliev et al1-6, 2014, 2015, 2016).
ARTICLE | doi:10.20944/preprints201608.0209.v1
Subject: Computer Science And Mathematics, Applied Mathematics Keywords: bivariate generalized power series distribution; ruin probability; aggregate claims distribution
Online: 26 August 2016 (09:43:14 CEST)
In this paper we consider type II bivariate generalized power series Poisson distribution as a compound Poisson distribution with bivariate generalized power series compounding distribution. We obtain some properties, p.m.f. and conditional distributions. In addition we also give a brief discussion about the multivariate extension of this case. Then we introduce type II bivariate generalized power series Poisson process and consider a bivariate risk model with type II bivariate generalized power series Poisson model as the counting process. For this model we derive distribution of the time to ruin and bounds for the probability of ruin. We obtain partial integro-differential equation for the ruin probabilities and express its bivariate transform through two univariate boundary transforms,where one of the initial capitals is fixed at zero.
ARTICLE | doi:10.20944/preprints202108.0131.v1
Subject: Engineering, Automotive Engineering Keywords: recycled concrete aggregate; construction waste; shear strength; shear provision; design equation
Online: 5 August 2021 (09:41:27 CEST)
The brittle shear failure of reinforced concrete beams is complexed and unfavorable. For decades, research on the mechanical properties and durability of recycled coarse aggregate (RCA) to make recycled aggregate concrete (RAC) has been widely investigated. However, test results on the shear strength of reinforced recycled aggregate concrete beams are still limited and contradictory. This paper reports the shear strength of reinforced recycled aggregate concrete beams without stirrups. Eight RAC beams and two controlled beams with natural coarse aggregate (NCA) were tested under the four-point flexural test with the shear span-to-effective depth ratio (a/d) of 3.10. Parameters in this study were the replacement percentage of RCA (0%, 25%, 50%, 75%, and 100%) and longitudinal reinforcement ratio (w) of 1.16% and 1.80%. It was found that the normalized shear stresses of RAC beams with w = 1.80% at all levels of replacement percentage were quite similar to that of the NAC counterparts. Normalized shear stress of the beam with 100% RCA and w = 1.16% was lower than that of the NAC beam by 5%. Database of 128 RAC beams without shear reinforcement from literature was analyzed to evaluate the ability of the most recent ACI 318-19 shear provisions in shear strength prediction. A reduction factor of 0.75 is proposed to the current ACI code provision to account for the physical variations of RCA such as replacement percentage, RCA source and quality, density, amount of residual mortar, and physical irregularity.
ARTICLE | doi:10.20944/preprints202007.0302.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: 2-methacryloyloxyethyl phosphorylcholine polymer; amphiphilic nature; cationic group; polymer aggregate; endocytosis
Online: 14 July 2020 (11:28:18 CEST)
Water-soluble and cytocompatible polymers were investigated to enhance a transporting efficiency of biomolecules into cells in vitro. The polymers composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) unit, a hydrophobic monomer unit, and a cationic monomer unit bearing an amino group were synthesized for complexation with model biomolecules, siRNA. The cationic MPC polymer was shown to interact with both siRNA and the cell membrane and was successively transported siRNA into cells. When introducing 20 − 50 mol% hydrophobic units into the cationic MPC polymer, transport of siRNA into cells. The MPC units (10 − 20 mol%) in the cationic MPC polymer were able to impart cytocompatibility, while maintaining interaction with siRNA and the cell membrane. The level of gene suppression of the siRNA/MPC polymer complex was evaluated in vitro and it was as the same level as that of a conventional siRNA transfection reagent, whereas its cytotoxicity was significantly lower. We concluded that these cytocompatible MPC polymers may be promising complexation reagent for introducing biomolecules into cells, with the potential to contribute to future fields of biotechnology, such as in vitro evaluation of gene functionality, and the production of engineered cells with biological functions.
ARTICLE | doi:10.20944/preprints202005.0424.v1
Subject: Engineering, Civil Engineering Keywords: curing conditions; carbonated recycled concrere aggregate; eco-efficiency indexes; eco-efficient index
Online: 26 May 2020 (08:18:52 CEST)
The paper presents the influence of different curing conditions – wet, dry and protection against water evaporation on selected properties of concretes with different amount of recycled concrete aggregate previously subjected to atmospheric CO2 sequestration. Additionally, the eco-efficiency bi and ci indexes as well as eco-durability S-CO2 index were calculated. It was found that dry conditions deteriorate the properties of concrete, especially made of blast furnace slag cement, while protection against evaporation allows to achieve results comparable to wet conditions. Moreover, for series with the highest amount of coarse recycled aggregate and after longer period of curing, the difference between the effects of wet curing and protection against water evaporation disappears. The eco-efficiency and eco-durability indexes approach confirms the beneficial effect of blast-furnace slag cement used as a binder but on condition of proper way of curing.
BRIEF REPORT | doi:10.20944/preprints201912.0084.v1
Subject: Biology And Life Sciences, Virology Keywords: zika virus; unfolded protein response; persistent er stress; aggregate; non-native disulfide bond
Online: 6 December 2019 (13:28:38 CET)
Flaviviruses replicate in membranous factories associated with the endoplasmic reticulum (ER). Significant levels of flavivirus polyprotein integration contribute to ER stress and the host cell may exhibit an Unfolded Protein Response (UPR) to this protein accumulation, stimulating appropriate cellular responses such as adaptation, autophagy or cell death. These different stress responses support other antiviral strategies initiated by infected cells and can help to overcome viral infection. In epithelial A549 cells, a model currently used to study the flavivirus infection cycle and the host cell responses, all three pathways leading to UPR are activated during infection by Dengue virus (DENV), Yellow Fever virus (YFV) or West Nile virus (WNV). In the present study, we investigated the capacity of ZIKA virus (ZIKV) to induce ER stress in A549 cells. We observed that the cells respond to ZIKV infection by implementing an UPR through activation of the IRE1 and PERK pathway without activation of the ATF6 branch. By modulating the ER stress response, we found that UPR inducers significantly inhibit ZIKV replication. Interestingly, our findings provide evidence that ZIKV could manipulate the UPR to escape this host cell defence system. Since incomplete UPR could lead to unresolved and persistent ER stress, we found that ZIKV infection was associated with an abnormal accumulation of viral envelope proteins, which were aggregated with non-native disulfide bridges. As the presence of these “amyloid like” protein polymers may be cytopathic, our observations provide new insights into specific neuropathologies associated with ZIKA virus infections.
ARTICLE | doi:10.20944/preprints201610.0006.v1
Subject: Chemistry And Materials Science, Other Keywords: steel slag; electric arc furnace slag; magnetite; radiation shielding concrete; concrete; EAF; aggregate
Online: 4 October 2016 (09:28:42 CEST)
Electric arc furnace oxidizing slag (EAF) has a high density of 3.0~3.7 t/m3 and therefore has a high bulk density when mixed with concrete. Extensive research has been conducted on the use of concrete with high unit volume weight as heavyweight concrete for radiation shielding concrete. In this study, to examine the possibility of developing a radiation shielding concrete, the physical properties of normal concrete, magnetite concrete, EAF concrete, and EAF concrete with added iron powder, were compared. Also, their radiation shielding performance was assessed through shielding tests against X-rays and γ-rays. While the unit volume weight of EAF concrete (3.21 t/m3) appeared lower than that of magnetite concrete (3.5 t/m3), the compressive strength of EAF concrete was greater than those of magnetite and normal concretes. The radiation shielding ratio of magnetite concrete was observed to be 93.9% from the X-ray shielding test, followed by 91.2% of EAF concrete, and 73.7% of normal concrete, indicating a linear relationship with unit volume weight. From the γ-ray shielding test, the performance of EAF and magnetite concretes appeared to be similar. Based on the excellent physical properties and radiation shielding performance of EAF concrete, its potential applicability as radiation shielding concrete was confirmed.
ARTICLE | doi:10.20944/preprints202304.0155.v1
Subject: Engineering, Architecture, Building And Construction Keywords: Density; Pre-soaking; High strength concrete, Lightweight plant-based aggregate; Mechanical properties; Environmentally friendly
Online: 10 April 2023 (07:08:54 CEST)
This research investigates the effect of pre-soaking treatment on plant-based aggregate using a wet grout binder to formulate a high-strength lightweight concrete (HSLWC). The surface modification utilising a novel grout soaking technique with various water-to-cement (w/c) ratios indicated a new method of approach for the recent development of lightweight plant-based aggregate (LWPA). In this experiment, the fresh and hardened properties of modified LWPA lightweight concrete were assessed by verifying their workability, densities, compressive and split tensile strengths towards the modulus of elasticity. The results showed that pre-soaking plant-based lightweight aggregate (w/c: 0.6, 0.8, 1.0, and 1.2) slightly increased the density of the samples compared to untreated LWPA. The oven-dry density of treated and untreated LWPA is controlled in the range of HSLWC. The outcomes indicated that the workability of the surface- modified LWPA has significant improvement up to 40% in 6 min for (TDS)/0.6 sample compared to the original LWPA. The mechanical properties of the LWPA concrete with surface modification method exhibit substantial increment of compressive strength, split tensile strength, and modulus of elasticity were recorded at 22%, 26%, and 34%, respectively. Significantly, the findings from this scientific method revealed that the pre-soaking treatment method on LWPA has shown to be a highly recommended technique in improving interfacial bonding while performing as one of the most promising solutions to improve the properties of lightweight concrete.
ARTICLE | doi:10.20944/preprints201811.0261.v1
Subject: Engineering, Civil Engineering Keywords: expanded glass; expanded clay; lightweight aggregate concrete; microfiller; alkali-silica reaction; freeze-thaw resistance
Online: 12 November 2018 (04:37:43 CET)
This study is focused on the experimental investigation of compressive strength and durability properties of lightweight concrete mixtures with fine expanded glass and expanded clay aggregates using different microfillers. The paper proposes the relationships between the compressive strength and density of concrete mixtures with different proportions of lightweight aggregates mentioned above. The performed experimental studies have revealed the tendencies of possible usage of different amount of fine lightweight aggregates and their combinations in the production of concrete mixtures depending on the demands of practical application. Following the requirements for structural concrete subjected to environmental effects, durability properties (alkaline corrosion and freeze–thaw resistance) of the selected concrete mixtures with expanded glass aggregate were studied. The results of the experimental investigations have shown that durability of tested concrete specimens was sufficient. The study has concluded that the mixtures under consideration can be applied for the production of structural elements to which durability requirements are significant.
ARTICLE | doi:10.20944/preprints202306.0037.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: tricalcium silicate nanoparticle-containing cement (NPC); mineral trioxide aggregate (MTA); human periodontal ligament fibroblasts (HPLFs)
Online: 1 June 2023 (05:30:27 CEST)
A tricalcium silicate nanoparticle-containing cement (NPC) was developed to overcome the disadvantages of existing mineral trioxide aggregate (MTA) dental materials. This study aimed at evaluating the effects of NPC on the osteogenic differentiation of human periodontal ligament fibroblasts (HPLFs) in vitro, and on the healing of furcal perforations created experimentally in rat molars in vivo, in comparison to MTA. The in vitro studies performed the following assays; pH measurement using a pH meter, the release of calcium ions using a calcium assay kit, cell attachment and morphology using SEM, cell proliferation using a coulter counter, marker expression using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and cell mineralized deposit formation using Alizarin Red S (ARS) staining. In the in vivo studies, MTA and NPC were used to fill the rat molar perforations. Rat molars were processed at 7, 14 and 28 days for analysis of inflammatory processes using hematoxylin and eosin (HE) staining, immunohistochemical staining of Runx2 and tartrate-resistant acid phosphate (TRAP) staining. The results demonstrate that the nanoparticle size distribution of NPC is critical for osteogenic potential at an earlier stage compared to MTA. Further studies are required to elucidate the mechanism of action of NPC in osteogenic differentiation.
ARTICLE | doi:10.20944/preprints202305.0382.v1
Subject: Engineering, Civil Engineering Keywords: carbon fiber composites; recycled concrete; recycled aggregate replacement rate; levels of seismic damage; pseudo-static test
Online: 6 May 2023 (05:32:27 CEST)
To study the strengthening effect on recycled concrete columns by carbon fiber composite materials (CFRP) under different levels of seismic damage, four column specimens were designed for pseudo-static tests. The four specimens were respectively non-destructive without strengthening (prototype), non-destructive strengthening, medium seismic damage strengthening and severe seismic damage strengthening, according to the replacement rate of recycled aggregates and the level of seismic damage. The characteristics of the deformation damage and seismic performance indicators of each specimen were compared and analyzed. A decrease was observed in the initial stiffness of the seismically damaged recycled concrete column specimens strengthened with CFRP, while the ductility, peak bearing capacity and energy dissipation capacity of the specimens were improved. On the other hand, with the reduction of seismic damage and the increase of recycled aggregate replacement rate, the ductility and energy dissipation capacity of the reinforced seismic damaged recycled concrete column specimens were enhanced to different levels. In particular, the cumulative energy consumption of the strengthened specimens under medium seismic damage increased most significantly by 32.5%. In general, the hysteretic curves of the strengthened specimens were full, and the average ductility coefficients were 4.1–6.8. CFRP strengthening was more effective in restoring and enhancing the performance of the recycled concrete column specimens with medium and lower seismic damage levels (displacement ratio ≤ 3%).
ARTICLE | doi:10.20944/preprints202007.0602.v1
Subject: Engineering, Civil Engineering Keywords: recycled crushed concrete aggregate; reclaimed asphalt pavement; unconfined compressive strength; Microstructure; scanning electron microscope; image analysis
Online: 25 July 2020 (11:07:49 CEST)
The reuse of recycled crushed concrete aggregate (RCCA) and reclaimed asphalt pavement (RAP) can provide a sustainable solution for the disposal of C&D materials instead of sending it to landfill. More importantly, it will save energy and reduce impact on the environment. Several states in USA are using RCCA and RAP as base materials for years, focusing on the quality of the recycled materials. The structure of Recycled Aggregate (RA) is more complex than Natural Aggregate (NA). RAs have old mortar adhered on them that forms a porous surface at interfacial transition Zone (ITZ) and prevents new cement mix from bonding strongly with the aggregates. The objective of this work was to correlate microstructural properties like micro-porosity, inter and intra aggregate pores with the unconfined compressive strength (UCS) of RAP and RCCA molds, mixed at different proportions. In this paper, the quantity of micro-pores and their effect on the strength of mixed materials is used as the basis of microstructural analysis of recycled concrete and reclaimed asphalt. Microstructural properties obtained from the analysis of scanning electron microscope (SEM) images were correlated with unconfined compressive strength. Intra-aggregate and inter-aggregate pores were studied for different ratios of cement treated mixture of RAP and RCCA. The results show that the number of pores in the mixture increases considerably by adding RAP, which eventually causes reduction in unconfined compressive strength. In addition, significant morphological and textural changes of recycled aggregates were observed by SEM image analysis.
ARTICLE | doi:10.20944/preprints202306.0098.v1
Subject: Computer Science And Mathematics, Probability And Statistics Keywords: Bayesian nonparametric model; heterogeneity; missing at random; log-normal sum approximation; aggregate insurance claims; clustering; generative model
Online: 1 June 2023 (13:47:57 CEST)
In actuarial practice, the modeling of total losses tied to a certain policy is a non-trivial task. Traditional parametric models to predict total losses have limitations due to complex distributional features such as extreme skewness, zero inflation, multi-modality, etc., and the lack of explicit solutions for log-normal convolution. In the recent literature, the application of the Dirichlet process mixture for insurance loss has been proposed to eliminate the risk of model misspecification biases; however, the effect of covariates as well as missing covariates in the modeling framework is rarely studied. In this article, we propose novel connections among covariate-dependent Dirichlet process mixture, log-normal convolution, and missing covariate imputation. Assuming an individual loss is log-normally distributed, we develop a log skew-normal Dirichlet process to approximate the log-normal sum. As a generative approach, our framework models the joint of outcome and covariates, which allows to impute missing covariates under the assumption of missingness at random. The performance is assessed by applying our model to several insurance datasets, and the empirical results demonstrate the benefit of our model compared to the existing actuarial models such as the Tweedie-based generalized linear model, generalized additive model, or multivariate adaptive regression spline.
ARTICLE | doi:10.20944/preprints201911.0259.v1
Subject: Engineering, Civil Engineering Keywords: lightweight aggregate concrete; reinforced concrete; flexural elements; curvature; short-term loading; tension stiffening; constitutive model; numerical modelling.
Online: 22 November 2019 (08:28:04 CET)
In the present trend of constructing taller and longer structures, the application of lightweight aggregate concrete is becoming an increasing important advanced solution in the modern construction industry. In engineering practice, the analysis of lightweight concrete elements is performed using the same algorithms used for normal concrete elements. As an alternative to traditional engineering methods, nonlinear numerical algorithms based on constitutive material models may be used. The paper presents a comparative analysis of curvature calculations for flexural lightweight concrete elements, incorporating analytical code methods EN 1992-1 and ACI 318-14, as well as a numerical analysis using the constitutive model of cracked tensile lightweight concrete recently proposed by the authors. To evaluate the adequacy of the theoretical predictions, experimental data of 51 lightweight concrete beams tested during five different programmes were collected. A comparison of theoretical and experimental results showed that the most accurate predictions are obtained using numerical analysis and the constitutive model proposed by the authors. In the future, the latter algorithm can be used as a reliable tool for improving the design standard methods or numerical modelling of lightweight concrete elements subjected to short-term loading.
Subject: Computer Science And Mathematics, Probability And Statistics Keywords: contagion risk; insurance premium; aggregate claims; default-free bond pricing; self-exciting process; Hawkes process; CIR process
Online: 28 August 2019 (04:00:41 CEST)
In this paper, we study a generalised CIR process with externally-exciting and self-exciting jumps, and focus on the distributional properties and applications of this process and its aggregated process. The first and second moments of this jump-diffusion process are used to calculate the insurance premium based on mean-variance principle. The Laplace transform of the aggregated process is derived, and this leads to an application for pricing default-free bonds which could capture the impacts of both exogenous and endogenous shocks. Illustrative numerical examples and comparisons with other models are also provided.
ARTICLE | doi:10.20944/preprints202112.0087.v1
Subject: Engineering, Civil Engineering Keywords: lightweight aggregate concrete; reinforced concrete; slab; bridge girder; curvature; short-term loading; tension stiffening; constitutive model; numerical modelling.
Online: 6 December 2021 (15:33:27 CET)
In the modern construction industry, lightweight aggregate concrete (LWAC) is often used in the production of load-bearing structural members. LWAC can be up to 40% lighter by volume in comparison to normal strength concrete. On the other hand, the lack of adequate numerical models often limits the practical application of innovative building materials, such as lightweight concrete, in real projects. This trend is due to the uncertainties in design standard methods and calculation errors, the level of which is generally unacceptable to civil engineers in terms of safety and reliability. In the present paper, a comparative numerical deformation analysis of a full-scale bridge deck slab and girder has been carried out. Using the physical model proposed by the authors and the finite element software ATENA, the deformations of full–scale lightweight and traditional reinforced concrete elements under short-term effects of permanent and variable loads was compared. Depending on the safety and serviceability limit requirements, it was found that the amount of longitudinal reinforcement in lightweight reinforced concrete elements can be reduced compared to normal reinforced concrete elements with the same parameters. The results of the numerical analysis show that the deformation analysis model proposed by the authors can be a reliable tool for the design of lightweight concrete flexural members by selecting the optimum geometrical and reinforcement parameters limited by the stiffness condition.
ARTICLE | doi:10.20944/preprints202112.0234.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: submerged arc; heat resistant steel; square waveform welding; aggregate quality index; bay area; melting efficiency; process; model; process map
Online: 14 December 2021 (12:46:10 CET)
The demand for efficient processes through a comprehensive understanding and optimization of welding conditions continues to grow in the manufacturing industry. This study involves heat-resistant 2.25 Cr-1 Mo V-groove steel welding using the square-waveform alternating cur-rent. Experiments were conducted to build the relationship between input variables—such as current, frequency, electrode negativity ratio, and welding speed—and process performance, such as penetration, bay area, deposition rate, melting efficiency, percentage dilution, flux–wire ratio, and heat input. The process was analyzed in light of the defect-free high-deposition weld groove weld, the sensitivity to process parameters, and the optimization and development of the process map. The study proposes an innovative approach to reducing the cost and time of optimizing the one-pass-each-layer V-groove welding process using bead-on-plate welds. Square waveform welding creates a metallurgical notch in the form of a bay at the fusion boundary that can be minimized by selecting appropriate welding conditions. The square waveform submerged arc welding is more sensitive towards changes in current and welding speed than the frequency and electrode negativity ratio; however, the electrode negativity ratio and frequency are minor but helpful parameters to achieve optimal results. The proximity of the planned and experimental results to within 3% confirms the validity of the proposed approach. The investigation shows that 90% of the maximum deposition rate is possible for one-pass-each-layer V-groove welds within heat input and weld width constraints.
ARTICLE | doi:10.20944/preprints202211.0217.v1
Subject: Arts And Humanities, Art Keywords: Lime mortars; bastard mortars; mortars with volcanic aggregate; mineralogy of historic mortars; Quito Cultural Heritage; Church of Santo Domingo of Quito
Online: 11 November 2022 (04:11:47 CET)
The pride of power of the Spanish preachers of religious art is reflected in the church of Santo Domingo built between 1541 and 1688. This work of heritage architecture, one of the first to be built in the colonized city, was affected by multiple earthquakes, interventions, and constructions that do not have a clear record. A total of 13 samples were taken from the lining mortar inside the cloister, central nave, and side chapel, following the nondestructive testing protocols and standards suggested by the research team. The analysis included mineral characterization studies and quantitative analysis by X-ray diffraction and scanning electron microscopy with microanalysis of the samples. The results showed the presence of volcanic aggregates and lime lining and joint mortars, mortars of rustic composition and coarse manufacture. The resolution of the data of mineralogical composition and texture has allowed us to corroborate the historical information described by the chroniclers and to date relatively the studied sites and to establish a hypothesis of constructive stages.
ARTICLE | doi:10.20944/preprints202012.0330.v1
Subject: Engineering, Automotive Engineering Keywords: Hot Mix Asphalt; Aggregate Stockpile; RAP; Remote Sensing; Unmanned Aerial Vehicle; Drone; Photogrammetry; Structure from Motion; Density; Volume Calculation; Life Cycle Assessment
Online: 14 December 2020 (12:49:52 CET)
This study introduces a remote sensing application using satellite imagery to survey a network-scale aggregate stockpile inventory. First, a real scale aggregate quarry site was surveyed using a small Unmanned Aerial Vehicle (sUAV) to produce digital terrain models that enabled analysis of aggregate pile geometry. Second, a lab experiment was designed and performed to validate the applicability of close-range Structure from Motion (SfM) photogrammetry for measuring aggregate piles' physical properties such as volume and density. The other part of the lab experiment delved into direct measurement of aggregate density under varying compaction efforts. These experimental results, in conjunction with some simplifying assumptions, enabled the calculation of aggregate stockpile volumes and estimated weights from satellite imagery. We estimated that an inventory of 4.4 and 1.1 million metric tons of crushed aggregates and Reclaimed Asphalt Pavement (RAP), respectively, stockpiled in Washington State for asphalt production in 2017. The merit of producing such database was further showcased in an example on the economic and environmental impacts of material transportation. We approximated that hauling aggregates from quarry plants to construction sites within Washington State incurs a cost of about $50 thousand to over $4 million, consumes about 0.25 to 20 TJ of energy, and emits 20 to over 1,500 tons of CO2-eq per asphalt plant annually.