Search results for: secondary raw material

Authors: Jianzheng Wei, Duo Zhen, Zhihan Yang, Huifeng Tan

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The deployable descent technology is a lightweight entry method using an inflatable heat shield. The heatshield consists of a pressurized core which is covered by different layers of thermal insulation and flexible ablative materials in order to protect against the thermal loads. In this paper, both aluminum and silicon-aluminum aerogels were prepared by freeze-drying method. The latter material has bigger specific surface area and nano-scale pores. Mullite fibers are used as the reinforcing fibers to prepare the aerogel matrix to improve composite flexibility. The flexible composite materials were performed as an insulation layer to an underlying aramid fabric by a thermal shock test at a heat flux density of 120 kW/m² and uniaxial tensile test. These results show that the aramid fabric with untreated mullite fibers as the thermal protective layer is completely carbonized at the heat of about 60 s. The aramid fabric as a thermal resistance layer of the composite material still has good mechanical properties at the same heat condition.

Keywords: aerogel, aramid fabric, flexibility, thermal resistance

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Authors: Arzyana Sunkar, Yanto Santosa, Intan Purnamasari, Yohanna Dalimunthe

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A variety of negative allegations have criticized the Indonesian oil palm plantations as being environmentally unfriendly. One of the important allegations thus must be verified is that expansion of Indonesian oil palm plantation has increased the deforestation rate of primary tropical forest. In relation to this, a research was conducted to study the origin or history of the status and land use of 8 private oil palm plantations (with a total of 46,372.38 ha) located in Riau Province. Several methods were employed: (1) conducting analysis of overlay maps between oil palm plantation studied with the 1986 Forest Map Governance Agreement (TGHK) and the 1994 and 2014 Riau Provincial Spatial Plans(RTRWP); (2) studying the Cultivation Right on Land (HGU) documents including the Forestry Ministerial Decree on the release of forest area and (3) interpretation of lands at imagery of bands 542, covering 3 years before and after the oil palm industries operated. In addition, field cross-checked, and interviews were conducted with National Land Agency, Plantation and Forestry Office and community figures. The results indicated that as much as 1.95% of the oil palm plantations under study were converted from production forest, 30.34% from limited production forest and 67.70% from area for other usage /conversion production forest. One year prior to the establishment of the plantations, the land cover types comprised of rubber plantations (49.96%), secondary forest (35.99%), bare land (10.17%), shrubs (3.03%) and mixed dryland farming-shrubs (0.84%), whereas the land use types comprised of 35.99% forest concession areas, 14.04% migrants dryland farms, and 49.96% Cultivation Right on Land of other companies. These results indicated that most of the private oil palm plantations under study, resulted from the conversion of production forests and the previous land use were not primary forest but rubber plantations and secondary forests.

Keywords: land cover types, land use history, primary forest, private oil palm plantations

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Authors: Holly Sandberg, Christina McCoy, Khaled Mansy

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Eucalyptus Cloeziana, commonly known as Gympie Messmate, is a fast-growing hardwood native to Australia. Its quick growth makes it advantageous for carbon sequestering, while its strength class lends itself to structural applications. Market research shows that the demand for timber is growing, especially mass timber. An environmental product declaration, or EPD, for eucalyptus Cloeziana in the Australian market has been evaluated and compared to the EPD’s of steel and Douglas fir of the same region. An EPD follows a product throughout its life cycle, stating values for global warming potential, ozone depletion potential, acidification potential, eutrophication potential, photochemical ozone creation potential, and abiotic depletion potential. This paper highlights the market potential, as well as the environmental benefits and challenges to using Gympie Messmate as a structural building material. In addition, a case study is performed to compare steel, Douglas fir, and eucalyptus in terms of embodied carbon and structural weight within a single structural bay. Comparisons among the three materials highlight both the differences in structural capabilities as well as environmental impact.

Keywords: eucalyptus, timber, construction, structural, material

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Authors: Nicolas Bigot, M'hamed Boutaous, Nahiene Hamila, Shihe Xin

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Composite materials with polymer matrices are widely used in most industrial areas, particularly in aeronautical and automotive ones. Thanks to the development of a high-performance thermoplastic semicrystalline polymer matrix, those materials exhibit more and more efficient properties. The polymer matrix in composite materials can manifest a specific crystalline structure characteristic of crystallization in a fibrous medium. In order to guarantee a good mechanical behavior of structures and to optimize their performances, it is necessary to define realistic mechanical constitutive laws of such materials considering their physical structure. The interaction between fibers and matrix is a key factor in the mechanical behavior of composite materials. Transcrystallization phenomena which develops in the matrix around the fibers constitute the interphase which greatly affects and governs the nature of the fiber-matrix interaction. Hence, it becomes fundamental to quantify its impact on the thermo-mechanical behavior of composites material in relationship with processing conditions. In this work, we propose a numerical model coupling the thermal and crystallization kinetics in long fiber-based composite materials, considering both the spherulitic and transcrystalline types of the induced structures. After validation of the model with comparison to results from the literature and noticing a good correlation, a parametric study has been led on the effects of the thermal kinetics, the fibers volume fractions, the deformation, and the pressure on the crystallization rate in the material, under processing conditions. The ratio of the transcrystallinity is highlighted and analyzed with regard to the thermal kinetics and gradients in the material. Experimental results on the process are foreseen and pave the way to establish a mechanical constitutive law describing, with the introduction of the role on the crystallization rates and types on the thermo-mechanical behavior of composites materials.

Keywords: composite materials, crystallization, heat transfer, modeling, transcrystallization

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Authors: Erwin Stolz, Hannes Mayerl, Anja Waxenegger, Wolfgang Freidl

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Research has often found poverty associated with adverse health outcomes, but it is unclear which (interplay of) mechanisms actually translate low economic resources into poor physical health. The goal of this study was to assess the impact of educational, material, psychosocial and behavioural factors in explaining the poverty-health association in old age. We analysed 28,360 observations from 11,390 community-dwelling respondents (65+) from the Survey of Health, Ageing and Retirement in Europe (SHARE, 2004-2013, 10 countries). We used multilevel growth curve models to assess the impact of combined income- and asset poverty risk on old age frailty index levels and trajectories. In total, 61.8% of the variation of poverty risk on frailty levels could be explained by direct and indirect effects, thereby highlighting the role of material and particularly psychosocial factors, such as perceived control and social isolation. We suggest strengthening social policy and public health efforts in order to fight poverty and its deleterious effects from early age on and to broaden the scope of interventions with regard to psychosocial factors.

Keywords: frailty, health inequality, old age, poverty

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Authors: Christoph Hacker, Zeynep Karahaliloglu, Gunnar Seide, Emir Baki Denkbas, Thomas Gries

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A wound dressing material is designed to facilitate wound healing and minimize scarring. An ideal wound dressing material should protect the wound from any contaminations of exogeneous microorganism. In addition, the dressing material should provide a moist environment through extraction of body fluid from the wound area. Recently, wound dressing electrospun nanofibrous membranes are produced by electrospinning from a polymer solution or a polymer melt. These materials have a great potential as dressing materials for wound healing because of superior properties such as high surface-to-volume ratio, high porosity with excellent pore interconnectivity. Melt electrospinning is an attractive tissue engineering scaffold manufacturing process which eliminated the health risk posed by organic solvents used in electrospinning process and reduced the production costs. In this study, antibacterial wound dressing materials were prepared from TPU (Elastollan 1185A) by a melt-electrospinning technique. The electrospinning parameters for an efficient melt-electrospinning process of TPU were optimized. The surface of the fibers was modified with poly(ethylene glycol) (PEG) by radio-frequency glow discharge plasma deposition method and with silver nanoparticles (nAg) to improve their wettability and antimicrobial properties. TPU melt-electrospun mats were characterized using SEM, DSC, TGA and XPS. The cell viability and proliferation on modified melt-electrospun TPU mats were evaluated using a mouse fibroblast cell line (L929). Antibacterial effects of theirs against both Staphylococcus aureus strain and Escherichia coli were investigated by disk-diffusion method. TPU was successfully processed into a porous, fibrous network of beadless fibers in the micrometer range (4.896±0.94 µm) with a voltage of 50 kV, a working distance of 6 cm, a temperature of the thermocouple and hot coil of 225–230ºC, and a flow rate of 0.1 mL/h. The antibacterial test indicated that PEG-modified nAg-loaded TPU melt-electrospun structure had excellent antibacterial effects and cell study results demonstrated that nAg-loaded TPU mats had no cytotoxic effect on the fibroblast cells. In this work, the surface of a melt-electrospun TPU mats was modified via PEG monomer and then nAg. Results showed melt-electrospun TPU mats modified with PEG and nAg have a great potential for use as an antibacterial wound dressing material and thus, requires further investigation.

Keywords: melt electrospinning, nanofiber, silver nanoparticles, wound dressing

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Authors: Ozen Asut, Gulifeiya Abuduxike, Imge Begendi, Mustafa O. Canatan, Merve Colak, Gizem Ozturk, Lara Tasan, Ahmed Waraiet, Songul A. Vaizoglu, Sanda Cali

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Obesity among children and adolescents is one of the critical public health problems worldwide. Internet addiction is one of the sedentary behaviors that cause obesity due to the excessive screen time and reduced physical activities. We aimed to examine the relationships between the screen time, internet addiction and other lifestyle behaviors with obesity among high school students in the Near East College in Nicosia, Northern Cyprus. A cross-sectional study conducted among 469 secondary school students, mean age 11.95 (SD, 0.81) years. A self-administrated questionnaire was applied to assess the screen time and lifestyle behaviors. The Turkish adopted version of short-form of internet addiction test was used to assess internet addiction problems. Height and weight were measured to calculate BMI and classified based on the BMI percentiles for sex and age. Descriptive analysis, Chi-Square test, and multivariate regression analysis were done. Of all, 17.2% of the participants were overweight and obese, and 18.1% had internet addictions, while 40.7% of them reported having screen time more than two hours. After adjusting the analysis for age and sex, eating snacks while watching television (OR, 3.04; 95% CI, 1.28-7.21), self- perceived body weight (OR, 24.9; 95% CI, 9.64-64.25) and having a play station in the room (OR, 4.6; 95% CI, 1.85 - 11.42) were significantly associated with obesity. Screen time (OR, 4.68; 95% CI, 2.61-8.38; p=0.000) and having a computer in bedroom (OR, 1.7; 95% CI, 1.01- 2.87; p=0.046) were significantly associated with internet addiction, whereas parent’s compliant regarding the lengthy technology use (OR, 0.23; 95% CI, 0.11-0.46; p=0.000) was found to be a protective factor against internet addiction. Prolonged screen time, internet addiction, sedentary lifestyles, and reduced physical and social activities are interrelated, multi-dimensional factors that lead to obesity among children and adolescents. A family - school-based integrated approach should be implemented to tackle obesity problems.

Keywords: adolescents, internet addiction, lifestyle, Northern Cyprus, obesity, screen time

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Authors: Jonathan Sahu, Jill Aylott

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Individuals with Autism, Intellectual and Developmental disabilities (AIDD) are one of the most vulnerable groups in society, hampered not only by their own limitations to understand and interact with the wider society, but also societal limitations in perception and understanding. Communication to express their needs and wishes is fundamental to enable such individuals to live and prosper in society. This research project was designed as an organisational case study, in a large secondary health care hospital within the National Health Service (NHS), to assess the quality of care provided to people with AIDD and to review the role of advocacy to reduce health inequalities in these individuals. Methods: The research methodology adopted was as an “insider researcher”. Data collection included both quantitative and qualitative data i.e. a mixed method approach. A semi-structured interview schedule was designed and used to obtain qualitative and quantitative primary data from a wide range of interdisciplinary frontline health care workers to assess their understanding and awareness of systems, processes and evidence based practice to offer a quality service to people with AIDD. Secondary data were obtained from sources within the organisation, in keeping with “Case Study” as a primary method, and organisational performance data were then compared against national benchmarking standards. Further data sources were accessed to help evaluate the effectiveness of different types of advocacy that were present in the organisation. This was gauged by measures of user and carer experience in the form of retrospective survey analysis, incidents and complaints. Results: Secondary data demonstrate near compliance of the Organisation with the current national benchmarking standard (Monitor Compliance Framework). However, primary data demonstrate poor knowledge of the Mental Capacity Act 2005, poor knowledge of organisational systems, processes and evidence based practice applied for people with AIDD. In addition there was poor knowledge and awareness of frontline health care workers of advocacy and advocacy schemes for this group. Conclusions: A significant amount of work needs to be undertaken to improve the quality of care delivered to individuals with AIDD. An operational strategy promoting the widespread dissemination of information may not be the best approach to deliver quality care and optimal patient experience and patient advocacy. In addition, a more robust set of standards, with appropriate metrics, needs to be developed to assess organisational performance which will stand the test of professional and public scrutiny.

Keywords: advocacy, autism, health inequalities, intellectual developmental disabilities, quality of care

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Authors: J. O. Akinyele, R. W. Salim, K. O. Oikelome, O. T. Olateju

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Rice Husk (RH) is the major byproduct in the processing of paddy rice. The management of this waste has become a big challenge to some of the rice producers, some of these wastes are left in open dumps while some are burn in the open space, and these two actions have been contributing to environmental pollution. This study evaluates an alternative waste management of this agricultural product for use as a civil engineering material. The RH was burn in a controlled environment to form Rice Husk Ash (RHA). The RHA was mix with lateritic clay at 0, 2, 4, 6, 8, and 10% proportion by weight. Chemical test was conducted on the open burn and controlled burn RHA with the lateritic clay. Physical test such as particle size distribution, Atterberg limits test, and density test were carried out on the mix material. The chemical composition obtained for the RHA showed that the total percentage compositions of Fe2O3, SiO2 and Al2O3 were found to be above 70% (class “F” pozzolan) which qualifies it as a very good pozzolan. The coefficient of uniformity (Cu) was 8 and coefficient of curvature (Cc) was 2 for the soil sample. The Plasticity Index (PI) for the 0, 2, 4, 6, 8. 10% was 21.0, 18.8, 16.7, 14.4, 12.4 and 10.7 respectively. The work concluded that RHA can be effectively used in hydraulic barriers and as a stabilizing agent in soil stabilization.

Keywords: rice husk ash, pozzolans, paddy rice, lateritic clay

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Authors: Mikael M. Johansson, Peter Stenvall, Leif Karlsson, Joel Andersson

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Sandvik Sanicro 25, UNS S31035, is an advanced high temperature austenitic stainless steel that potentially can be used in super-heaters and reheaters in the next generation of advanced ultra-super critical power plants. The material possesses both high creep strength and good corrosion resistance at temperatures up to 700°C. Its high temperature properties are positioned between other commercially available high temperature austenitic stainless steels and nickel-based alloys. It is, however, well known that an austenitic solidification mode combined with a fully austenitic microstructure exacerbate susceptibility towards hot cracking. The problem increases even more for thick walled material in multipass welding and could compromise the integrity of the welded component. Varestraint weldability testing is commonly used to evaluate susceptibility towards hot cracking of materials. In this paper, Varestraint test results are evaluated for base material of both UNS S31035 steel and are compared to those of the well-known and well-characterized UNS S31008 grade. The more creep resistant alloy, UNS S31035, is metallurgically more complicated than the UNS S31008 grade and has additions of several alloying elements to improve its high temperature properties. It benefits from both solid solution hardening as well as precipitation hardening. This investigation therefore attempts, based on the Varestraint weldability test, to understand if there are any differences in cracking mechanisms between these two grades due to the additional alloying elements used in UNS S31035. Results from Varestraint testing and crack type investigations will be presented and discussed in some detail. It is shown that hot cracking susceptibility of the UNS S31035 steel is only slightly higher than that of UNS S31008 despite the more complicated metallurgy. Weldability of the two alloys is therefore judged to be comparable making the newer alloy well suited also for critical applications.

Keywords: austenitic stainless steel, hot cracking susceptibility, UNS S31035, UNS S31008, varestraint weldability testing

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Authors: Sarolta Lipóczi, Ildikó Szabó

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The use of ICT in European Schools has increased over the last decade but there is still room for improvement. Also interactive technology is often used below its technical and pedagogical potentials. The pedagogical potential of interactive technology in classrooms has not yet reached classrooms in different countries and in a substantial way. To develop these materials cooperation between educational researchers and teachers from different backgrounds is necessary. INTACT project brings together experts from science education, mathematics education, social science education and foreign language education – with a focus on bilingual education – and teachers in secondary and primary schools to develop a variety of pedagogically qualitative interactive teaching and learning resources. Because of the backgrounds of the consortium members INTACT project focuses on the areas of science, mathematics and social sciences. To combine these two features (science/math and foreign language) the project focuses on bilingual education. A big issue supported by ‘interactiveness’ is social and collaborative learning. The easy way to communicate and collaborate offered by web 2.0 tools, mobile devices connected to the learning material allows students to work and learn together. There will be a wide range of possibilities for school co-operations at regional, national and also international level that allows students to communicate and cooperate with other students beyond the classroom boarders while using these interactive teaching materials. Opening up the learning scenario enhance the social, civic and cultural competences of the students by advocating their social skills and improving their cultural appreciation for other nations in Europe. To enable teachers to use the materials in indented ways descriptions of successful learning scenarios (i.e. using design patterns) will be provided as well. These materials and description will be made available to teachers by teacher trainings, teacher journals, booklets and online materials. The resources can also be used in different settings including the use of a projector and a touchpad or other technical interactive devices for the input i.e. mobile phones. Kecskemét College as a partner of INTACT project has developed two teaching and learning resources in the area of foreign language teaching. This article introduces these resources as well.

Keywords: bilingual educational settings, international cooperation, interactive teaching and learning resources, work across culture

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Authors: Raphaelle Guillou, Matthieu Le Saux, Jean-Christophe Brachet, Thomas Guilbert, Elodie Rouesne, Denis Menut, Caroline Toffolon-Masclet, Dominique Thiaudiere

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In some hypothetical accidental situations, such as during a Loss Of Coolant Accident (LOCA) in pressurized water reactors, fuel cladding tubes made of zirconium alloys can be exposed for a few minutes to steam at High Temperature (HT up to 1200°C) before being cooled and then quenched in water. Under LOCA-like conditions, the cladding undergoes a number of metallurgical changes (phase transformations, oxygen diffusion and growth of an oxide layer...) and is consequently submitted to internal stresses whose state evolves during the transient. These stresses can have an effect on the oxide structure and the oxidation kinetics of the material. They evolve during cooling, owing to differences between the thermal expansion coefficients of the various phases and phase transformations of the metal and the oxide. These stresses may result in the failure of the cladding during quenching, once the material is embrittled by oxidation. In order to progress in the evaluation of these internal stresses, X-ray diffraction experiments were performed in-situ under synchrotron radiation during HT oxidation and subsequent cooling on Zircaloy-4 sheet samples. First, structural evolutions, such as phase transformations, have been studied as a function of temperature for both the oxide layer and the metallic substrate. Then, internal stresses generated within the material oxidized at temperatures between 700 and 900°C have been evaluated thanks to the 2θ diffraction peak position shift measured during the in-situ experiments. Electron backscatter diffraction (EBSD) analysis was performed on the samples after cooling in order to characterize their crystallographic texture. Furthermore, macroscopic strains induced by oxidation in the conditions investigated during the in-situ X-ray diffraction experiments were measured in-situ in a dilatometer.

Keywords: APRP, stains measurements, synchrotron diffraction, zirconium allows

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Authors: Sofia N. Gonçalves, Duarte M. S. Albuquerque, José C. F. Pereira

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The energy transition is spurred by structural changes in energy demand, supply, and prices. Microwave technology was first proposed as a faster alternative for cooking food. It was found that food heated instantly when interacting with high-frequency electromagnetic waves. The dielectric properties account for a material’s ability to absorb electromagnetic energy and dissipate this energy in the form of heat. Many energy-intense industries could benefit from electromagnetic heating since many of the raw materials are dielectric at high temperatures. Limestone sedimentary rock is a dielectric material intensively used in the cement industry to produce unslaked lime. A numerical 3D model was implemented in COMSOL Multiphysics to study the limestone continuous processing under microwave heating. The model solves the two-way coupling between the Energy equation and Maxwell’s equations as well as the coupling between heat transfer and chemical interfaces. Complementary, a controller was implemented to optimize the overall heating efficiency and control the numerical model stability. This was done by continuously matching the cavity impedance and predicting the required energy for the system, avoiding energy inefficiencies. This controller was developed in MATLAB and successfully fulfilled all these goals. The limestone load influence on thermal decomposition and overall process efficiency was the main object of this study. The procedure considered the Verification and Validation of the chemical kinetics model separately from the coupled model. The chemical model was found to correctly describe the chosen kinetic equation, and the coupled model successfully solved the equations describing the numerical model. The interaction between flow of material and electric field Poynting vector revealed to influence limestone decomposition, as a result from the low dielectric properties of limestone. The numerical model considered this effect and took advantage from this interaction. The model was demonstrated to be highly unstable when solving non-linear temperature distributions. Limestone has a dielectric loss response that increases with temperature and has low thermal conductivity. For this reason, limestone is prone to produce thermal runaway under electromagnetic heating, as well as numerical model instabilities. Five different scenarios were tested by considering a material fill ratio of 30%, 50%, 65%, 80%, and 100%. Simulating the tube rotation for mixing enhancement was proven to be beneficial and crucial for all loads considered. When uniform temperature distribution is accomplished, the electromagnetic field and material interaction is facilitated. The results pointed out the inefficient development of the electric field within the bed for 30% fill ratio. The thermal efficiency showed the propensity to stabilize around 90%for loads higher than 50%. The process accomplished a maximum microwave efficiency of 75% for the 80% fill ratio, sustaining that the tube has an optimal fill of material. Electric field peak detachment was observed for the case with 100% fill ratio, justifying the lower efficiencies compared to 80%. Microwave technology has been demonstrated to be an important ally for the decarbonization of the cement industry.

Keywords: CFD numerical simulations, efficiency optimization, electromagnetic heating, impedance matching, limestone continuous processing

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Authors: Kevin Brochard, Herve Le Sourne, Guillaume Barras

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The design of a submarine’s hull is crucial for its operability and crew’s safety, but also complex. Indeed, engineers need to balance lightness, acoustic discretion and resistance to both immersion pressure and environmental attacks. Submarine explosions represent a first-rate threat for the integrity of the hull, whose behavior needs to be properly analyzed. The presented work is focused on the development of a simplified analytical method to study the structural response of a deeply immersed cylinder submitted to an underwater explosion. This method aims to provide engineers a quick estimation of the resulting damage, allowing them to simulate a large number of explosion scenarios. The present research relies on the so-called plastic string on plastic foundation model. A two-dimensional boundary value problem for a cylindrical shell is converted to an equivalent one-dimensional problem of a plastic string resting on a non-linear plastic foundation. For this purpose, equivalence parameters are defined and evaluated by making assumptions on the shape of the displacement and velocity field in the cross-sectional plane of the cylinder. Closed-form solutions for the deformation and velocity profile of the shell are obtained for explosive loading, and compare well with numerical and experimental results. However, the plastic-string model has not yet been adapted for a cylinder in immersion subjected to an explosive loading. In fact, the effects of fluid-structure interaction have to be taken into account. Moreover, when an underwater explosion occurs, several pressure waves are emitted by the gas bubble pulsations, called secondary waves. The corresponding loads, which may produce significant damages to the cylinder, must also be accounted for. The analytical developments carried out to solve the above problem of a shock wave impacting a cylinder, considering fluid-structure interaction will be presented for an unstiffened cylinder. The resulting deformations are compared to experimental and numerical results for different shock factors and different standoff distances.

Keywords: immersed cylinder, rigid plastic material, shock loading, underwater explosion

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Authors: Gustavo Rodrigues, Hans Weber, Larissa Driemeier

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The prevision of post-impact conditions and the behavior of the bodies during the impact have been object of several collision models. The formulation from Hertz’s theory is generally used dated from the 19^th century. These models consider the repulsive force as proportional to the deformation of the bodies under contact and may consider it proportional to the rate of deformation. The objective of the present work is to analyze the behavior of the bodies during impact using the Finite Element Method (FEM) with elastic and plastic material models. The main parameters to evaluate are, the contact force, the time of contact and the deformation of the bodies. An advantage of using the FEM approach is the possibility to apply a plastic deformation to the model according to the material definition: there will be used Johnson–Cook plasticity model whose parameters are obtained through empirical tests of real materials. This model allows analyzing the permanent deformation caused by impact, phenomenon observed in real world depending on the forces applied to the body. These results are compared between them and with the model-based Hertz theory.

Keywords: collision, impact models, finite element method, Hertz Theory

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Authors: Ryan Villafuerte Lansangan

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Assessing students’ understanding in the microscopic level of an abstract subject like chemistry poses a challenge to teachers. Literature reveals that the use of representations serves as an essential avenue of measuring the extent of understanding in the discipline as an alternative to traditional assessment methods. This undertaking explored the representational competence profile of high school students from the University of Santo Tomas High School in understanding selected chemical principles and correlate this with their academic profile in chemistry based on their performance in the academic achievement examination in chemistry administered by the Center for Education Measurement (CEM). The common misconceptions of the students on the selected chemistry principles based on their representations were taken into consideration as well as the students’ views regarding their understanding of the role of chemical representations in their learning. The students’ level of representation task instrument consisting of the main lessons in chemistry with a corresponding scoring guide was prepared and utilized in the study. The study revealed that most of the students under study are unanimously rated as Level 2 (symbolic level) in terms of their representational competence in understanding the selected chemical principles through the use of chemical representations. Alternative misrepresentations were most observed on the students’ representations on chemical bonding concepts while the concept of chemical equation appeared to be the most comprehensible topic in chemistry for the students. Data implies that teachers’ representations play an important role in helping the student understand the concept in a microscopic level. Results also showed that the academic achievement in the chemistry of the students based on the standardized CEM examination has a significant association with the students’ representational competence. In addition, the students’ responses on the students’ views in chemical representations questionnaire evidently showed a good understanding of what a chemical representation or a mental model is by drawing a negative response that these tools should be an exact replica. Moreover, the students confirmed a greater appreciation that chemical representations are explanatory tools.

Keywords: chemical representations, representational competence, academic profile in chemistry, secondary students

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Authors: Neveen AlQasas, Daniel Johnson

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Membranes for water treatment are an established technology that attracts great attention due to its simplicity and cost effectiveness. However, membranes in operation suffer from the adverse effect of membrane fouling. Bio-fouling is a phenomenon that occurs at the water-membrane interface, and is a dynamic process that is initiated by the adsorption of dissolved organic material, including biomacromolecules, on the membrane surface. After initiation, attachment of microorganisms occurs, followed by biofilm growth. The biofilm blocks the pores of the membrane and consequently results in reducing the water flux. Moreover, the presence of a fouling layer can have a substantial impact on the membrane separation properties. Understanding the mechanism of the initiation phase of biofouling is a key point in eliminating the biofouling on membrane surfaces. The adhesion and attachment of different fouling materials is affected by the surface properties of the membrane materials. Therefore, surface properties of different polymeric materials had been studied in terms of their surface energies and Hansen solubility parameters (HSP). The difference between the combined HSP parameters (HSP distance) allows prediction of the affinity of two materials to each other. The possibilities of measuring the HSP of different polymer films via surface measurements, such as contact angle has been thoroughly investigated. Knowing the HSP of a membrane material and the HSP of a specific foulant, facilitate the estimation of the HSP distance between the two, and therefore the strength of attachment to the surface. Contact angle measurements using fourteen different solvents on five different polymeric films were carried out using the sessile drop method. Solvents were ranked as good or bad solvents using different ranking method and ranking was used to calculate the HSP of each polymeric film. Results clearly indicate the absence of a direct relation between contact angle values of each film and the HSP distance between each polymer film and the solvents used. Therefore, estimating HSP via contact angle alone is not sufficient. However, it was found if the surface tensions and viscosities of the used solvents are taken in to the account in the analysis of the contact angle values, a prediction of the HSP from contact angle measurements is possible. This was carried out via training of a neural network model. The trained neural network model has three inputs, contact angle value, surface tension and viscosity of solvent used. The model is able to predict the HSP distance between the used solvent and the tested polymer (material). The HSP distance prediction is further used to estimate the total and individual HSP parameters of each tested material. The results showed an accuracy of about 90% for all the five studied films

Keywords: surface characterization, hansen solubility parameter estimation, contact angle measurements, artificial neural network model, surface measurements

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Authors: Yohanes Kristianto

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The objective of this paper is to compose a sustainable supply chain that integrates product, process and networks design. An integrated life cycle assessment and techno-economic optimization is proposed that might deliver more economically feasible operations, minimizes environmental impacts and maximizes social contributions. Closed loop economy of the supply chain is achieved by reusing waste to be raw material of final products. Societal benefit is given by the supply chain by absorbing waste as source of raw material and opening new work opportunities. A case study of ethanol supply chain from rice straws is considered. The modeling results show that optimization within the scope of LCA is capable of minimizing both CO₂ emissions and energy and utility consumptions and thus enhancing raw materials utilization. Furthermore, the supply chain is capable of contributing to local economy through jobs creation. While the model is quite comprehensive, the future research recommendation on energy integration and global sustainability is proposed.

Keywords: life cycle assessment, techno-economic optimization, sustainable supply chains, closed loop economy

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Authors: Vitaly Haslavsky, Helena Vitoshkin

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The total energy saving effect of different types of greenhouse thermal/shade screens was determined by measuring and calculating the overall heat transfer coefficients (U-values) for single and several layers of screens. The measurements were carried out using the hot box method, and the calculations were performed according to the ISO Standard 15099. The goal was to examine different types of materials with a wide range of thermal radiation properties used for thermal screens in combination with a dehumidification system in order to improve greenhouse insulation. The experimental results were in good agreement with the calculated heat transfer coefficients. It was shown that a high amount of infra-red (IR) radiation can be blocked by the greenhouse covering material in combination with moveable thermal screens. The aluminum foil screen could be replaced by transparent screens, depending on shading requirements. The results indicated that using a single layer, the U-value was reduced by approximately 70% compared to covering material alone, while the contributions of additional screen layers containing aluminum foil strips could reduce the U-value by approximately 90%. It was shown that three screen layers are sufficient for effective insulation.

Keywords: greenhouse insulation, heat loss, thermal screens, U-value

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Authors: Danuvasin Charoen

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This study investigates the development of the digital economy policy in Thailand. The researcher describes the importance of digital technologies for competitiveness development of the country. In addition, the researcher analyzes the components and roadmap of the digital economy policy in Thailand. Main problems and challenges of the policy were identified. The data were gathered and analyzed from secondary sources. The finding can be used to guide the implementation of the digital economy in Thailand and other developing economies.

Keywords: digital economy, ICT in developing countries, Thailand, ICT development

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Authors: Gurbir Singh Khaira, Anmoldeep Singh Kang

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Exposures to environmental pollution remain a major source of health risk throughout the world, though risks are generally higher in developing countries, where poverty, lack of investment in modern technology and weak environmental legislation combine to cause high pollution levels. This paper will tell us about the environment is threatened severely by so many problems, some of which are caused by the activities of Construction Projects. The research reveals major environmental impacts of building construction projects to include environmental pollution, resource depletion and habitat destruction causing Destruction of ecosystem, Desertification, Soil Erosion and increasing Material Wastage. Construction is considered as one of the main sources of environmental pollution in the world, the level of knowledge and awareness of project participants, especially project managers, with regards to environmental impacts of construction processes needs to be enhanced. It was found that ‘Transportation Resource’, ‘Noise Pollution’, and ‘Dust Generation with Construction Machinery’ are the greatest environmental impacts in INDIA respectively. The results of this study are useful for construction managers and other participants in construction sites to become aware of construction processes impacts on the environment.

Keywords: construction projects, environmental impacts, material waste age, awareness

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Authors: Jaime Pizarro, Ximena Castillo

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The intensive use of water in agriculture, industry, human consumption and increasing pollution are factors that reduce the availability of water for future generations; the challenge is to advance in sustainable and low-cost solutions to reuse water and to facilitate the availability of the resource in quality and quantity. The use of new low-cost materials with sorbent capacity for pollutants is a solution that contributes to the improvement and expansion of water treatment and reuse systems. Fly ash, a residue from the combustion of coal in power plants that is produced in large quantities in newly industrialized countries, contains a high amount of silicon oxides and aluminum oxides, whose properties can be used for the synthesis of mesoporous materials. Properly functionalized, this material allows obtaining matrixes with high sorption capacity. The mesoporous materials have a large surface area, thermal and mechanical stability, uniform porous structure, and high sorption and functionalization capacities. The goal of this study was to develop hexagonal mesoporous siliceous material (HMS) for the adsorption of sulphate from industrial and mining waters. The silica was extracted from fly ash after calcination at 850 ° C, followed by the addition of water. The mesoporous structure has a surface area of 282 m2 g-1 and a size of 5.7 nm and was functionalized with ethylene diamine through of a self-assembly method. The material was characterized by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The capacity of sulphate sorption was evaluated according to pH, maximum load capacity and contact time. The sulphate maximum adsorption capacity was 146.1 mg g-1, which is three times higher than commercial sorbents. The kinetic data were fitted according to a pseudo-second order model with a high coefficient of linear regression at different initial concentrations. The adsorption isotherm that best fitted the experimental data was the Freundlich model.

Keywords: fly ash, mesoporous siliceous, sorption, sulphate

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Authors: G. Bharath, K. S. Reddy, Vivek Tandon, M. Amaranatha Reddy

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This paper presents the details of a study conducted to evaluate the interaction between recycled binder and fresh binder in Recycled Asphalt Pavement (RAP) mixes. When RAP is mixed with virgin aggregates in the presence of fresh binder there will be partial blending in a hot mix asphalt mixture. A recent approach used by some researchers for studying the degree of blending of RAP binder with virgin binder has been adopted in this study. Dense Bituminous Macadam mix of Ministry of Road Transport of India with a nominal maximum aggregate size of 19 mm was studied. Two proportions of RAP-20% and 35% and two types of virgin binders – viscosity grade VG10 and VG30 were considered. Design binder contents were determined for all the four types of mixes (two RAP contents and two virgin binders) as per Marshall mix design procedure. The degree of blending of RAP and virgin binders was evaluated in terms of the complex modulus of the binder. Laboratory test results showed that with an increase in RAP content, the degree of blending decreases. Better blending was observed for softer grade binder (VG10).

Keywords: blending, complex modulus, recycled asphalt pavement, virgin binder

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Authors: Elizaveta Startseva, Elena Notina, Irina Bykova, Valentina Ulyumdzhieva, Natallia Zhabo

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With the various existing models of intercultural communication that contain a vast number of stages for foreign language acquisition, there is a need for conscious perception of the foreign culture. Such a process is associated with the emergence of linguistic conflict with the consistent students’ desire to solve the problem of the language differences, along with cultural discrepancies. The aim of this study is to present the modern ways and methods of removing psycholinguistic conflict through skills development in professional translation and intercultural communication. The study was conducted in groups of 1-4-year students of Medical Institute and Agro-Technological Institute RUDN university. In the course of training, students got knowledge in such disciplines as basic grammar and vocabulary of the English language, phonetics, lexicology, introduction to linguistics, theory of translation, annotating and referencing media texts and texts in specialty. The students learned to present their research work, participated in the University and exit conferences with their reports and presentations. Common strategies of removing linguistic and cultural conflict can be attributed to the development of such abilities of a language personality as a commitment to communication and cooperation, the formation of cultural awareness and empathy of other cultures of the individual, realistic self-esteem, emotional stability, tolerance, etc. The process of mastering a foreign language and culture of the target language leads to a reduplication of linguistic identity, which leads to successive formation of the so-called 'secondary linguistic personality.' In our study, we tried to approach the problem comprehensively, focusing on the translation gaps for technical and non-technical language still missing such a typology which could classify all of the lacunas on the same principle. When obtaining the background knowledge, students learn to overcome the difficulties posed by the national-specific and linguistic differences of cultures in contact, i.e., to eliminate the gaps (to fill in and compensate). Compensation gaps is a means of fixing it, the initial phase of elimination, followed in some cases and some not is filling semantic voids (plenus). The concept of plenus occurs in most cases of translation gaps, for example in the transcription and transliteration of (intercultural and exoticism), the replication (reproduction of the morphemic structure of words or idioms. In all the above cases the task of the translator is to ensure an identical response of the receptors of the original and translated texts, since any statement is created with the goal of obtaining communicative effect, and hence pragmatic potential is the most important part of its contents. The practical value of our work lies in improving the methodology of teaching English for specific purposes on the basis of psycholinguistic concept of the secondary language personality.

Keywords: lacuna, language barrier, plenus, secondary language personality

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Authors: N. Piwpuan, J. Tosalee, N. Phonkerd

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Malachite green (MG), a synthetic dye, is used in industries and aquaculture and also disposed in the effluent. Use of wastewater in irrigation increases due to water shortage. However, wastewater containing dyes, MG, are toxic to biological systems. Therefore, effects of MG on growth of vegetables were evaluated in order to utilize dye-contaminated wastewater for irrigation. In this study, Pak choy (Brassica chinensis) and Chinese convolvulus (Ipomoea aquatica) were grown in growing material (mixture of soil, coconut fiber, and compost) for four weeks and afterward kept watering with 200 ml of tap water containing MG at the concentrations of 0 (control), 1, 2, 10, and 20 mg/L. At harvest, number of leaf and shoot and root dry weight of the treated plants were measured and compared with control. For both species, their biomass values were similar among treatments and did not differ from the control plants (dry weight were 0.6-1.0 and 1.1-1.7 g/plant for B. chinensis and I. aquatica, respectively). B. chinensis treated with 2, 10, and 20 mg/L of MG produced lower number of new leaf and had smaller and shorter leaf compared to control and treatment of 1 mg/L. These results indicate the different responses between plant species, which B. chinensis is more sensitive to contaminant compared to I. aquatica. There was no sign of MG and leucomalachite green (LMG) detected in root and shoot tissues of plants treated with MG at 20 mg/L, tested by thin layer chromatography. After plant harvest, toxicity of the growing material from all treatments was tested on mung beans. Percent germination (83-97%), seedling fresh weight (0.3-0.5 g/plant), and shoot length (11-12.5 cm) were similar to the control. These indicated that contaminant in growing material did not pose detrimental effect on mung beans. Based on these results, the water contaminated with low concentration of MG, such as discharge from aquaculture, may serve as ferti-irrigation water to compensate water shortage.

Keywords: ferti-irrigation, soil toxicity, triphenylmethane dye, wastewater reuse

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Authors: Viviana Letelier, Ester Tarela, Giacomo Moriconi

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The cement industry is responsible for around a 5% of the CO2 emissions worldwide and considering that concrete is one of the most used materials in construction its total effect is important. An alternative to reduce the environmental impact of concrete production is to incorporate certain amount of residuals in the dosing, limiting the replacement percentages to avoid significant losses in the mechanical properties of the final material. This study analyses the variation in the mechanical properties of structural concretes with recycled aggregates and volcanic ash as cement replacement to test the effect of the simultaneous use of different residuals in the same material. Analyzed concretes are dosed for a compressive strength of 30MPa. The recycled aggregates are obtained from prefabricated pipe debris with a compressive strength of 20MPa. The volcanic ash was obtained from the Ensenada (Chile) area after the Calbuco eruption in April 2015. The percentages of natural course aggregates that are replaced by recycled aggregates are of 0% and 30% and the percentages of cement replaced by volcanic ash are of 0%, 5%, 10% and 15%. The combined effect of both residuals in the mechanical properties of the concrete is evaluated through compressive strength tests after, 28 curing days, flexural strength tests after 28 days, and the elasticity modulus after 28 curing days. Results show that increasing the amount of volcanic ash used increases the losses in compressive strength. However, the use of up to a 5% of volcanic ash allows obtaining concretes with similar compressive strength to the control concrete, whether recycled aggregates are used or not. Furthermore, the pozzolanic reaction that occurs between the amorphous silica and the calcium hydroxide (Ca(OH)2) provokes an increase of a 10% in the compressive strength when a 5% of volcanic ash is combined with a 30% of recycled aggregates. Flexural strength does not show significant changes with neither of the residues. On the other hand, decreases between a 14% and a 25% in the elasticity modulus have been found. Concretes with up to a 30% of recycled aggregates and a 5% of volcanic ash as cement replacement can be produced without significant losses in their mechanical properties, reducing considerably the environmental impact of the final material.

Keywords: compressive strength of recycled concrete, mechanical properties of recycled concrete, recycled aggregates, volcanic ash as cement replacement

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Authors: Pebri Nurhayati, Rozanah Ahlam Fadiyah

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In the development of the city often use rural areas that can not be separated from the change in land use that lead to the degradation of urban green space in the city fringe. In the long run, the degradation of green open space this can impact on the decline of ecological, psychological and public health. Therefore, this research aims to (1) determine the relationship between the parameters of the degradation rate of urban development with green space, (2) develop a spatial model of the impact of urban development on the degradation of green open space with remote sensing techniques and Geographical Information Systems in an integrated manner. This research is a descriptive research with data collection techniques of observation and secondary data . In the data analysis, to interpret the direction of urban development and degradation of green open space is required in 2005-2010 ASTER image with NDVI. Of interpretation will generate two maps, namely maps and map development built land degradation green open space. Secondary data related to the rate of population growth, the level of accessibility, and the main activities of each city map is processed into a population growth rate, the level of accessibility maps, and map the main activities of the town. Each map is used as a parameter to map the degradation of green space and analyzed by non-parametric statistical analysis using Crosstab thus obtained value of C (coefficient contingency). C values were then compared with the Cmaximum to determine the relationship. From this research will be obtained in the form of modeling spatial map of the City Development Impact Degradation Green Space in Urban Fringe eastern city of Yogyakarta 2005-2010. In addition, this research also generate statistical analysis of the test results of each parameter to the degradation of green open space in the Urban Fringe eastern city of Yogyakarta 2005-2010.

Keywords: spatial analysis, urban development, degradation of green space, urban fringe

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Authors: Ali A. Sayadi, Thomas R. Neitzert, G. Charles Clifton

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Lightweight concrete is being used in the construction industry as a building material in its own right. Ultra-lightweight concrete can be applied as a filler and support material for the manufacturing of composite building materials. This paper is about the development of a stable and reproducible ultra-lightweight concrete with the inclusion of poly-lactic acid (PLA) beads and assessing the feasibility of PLA as a lightweight aggregate that will deliver advantages such as a more eco-friendly concrete and a non-petroleum polymer aggregate. In total, sixty-three samples were prepared and the effectiveness of mineral admixture, curing conditions, water-cement ratio, PLA ratio, EPS ratio and perlite ratio on compressive strength of perlite concrete are studied. The results show that PLA particles are sensitive to alkali environment of cement paste and considerably shrank and lost their strength. A higher compressive strength and a lower density was observed when expanded polystyrene (EPS) particles replaced PLA beads. In addition, a set of equations is proposed to estimate the water-cement ratio, cement content and compressive strength of perlite concrete.

Keywords: perlite concrete, poly-lactic acid (pla), expanded polystyrene (eps), concrete

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Authors: Damian Czubak

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The Białowieża Forest is a very valuable natural area, included in the World Natural Heritage at UNESCO, where, due to infestation by the bark beetle (Ips typographus), norway spruce (Picea abies) have deteriorated. This catastrophic scenario led to an increase in fire danger. This was due to the occurrence of large amounts of dead wood and grass cover, as light penetrated to the bottom of the stands. These factors in a dry state are materials that favour the possibility of fire and the rapid spread of fire. One of the objectives of the study was to monitor the quantitative and qualitative changes of combustible material on the permanent decay plots of spruce stands from 2012-2022. In addition, the size of the area with highly flammable vegetation was monitored and a classification of the stands of the Białowieża Forest by flammability classes was made. The key factor that determines the potential fire hazard of a forest is combustible material. Primarily its type, quantity, moisture content, size and spatial structure. Based on the inventory data on the areas of forest districts in the Białowieża Forest, the average fire load and its changes over the years were calculated. The analysis was carried out taking into account the changes in the health status of the stands and sanitary operations. The quantitative and qualitative assessment of fallen timber and fire load of ground cover used the results of the 2019 and 2021 inventories. Approximately 9,000 circular plots were used for the study. An assessment was made of the amount of potential fuel, understood as ground cover vegetation and dead wood debris. In addition, monitoring of areas with vegetation that poses a high fire risk was conducted using data from 2019 and 2021. All sub-areas were inventoried where vegetation posing a specific fire hazard represented at least 10% of the area with species characteristic of that cover. In addition to the size of the area with fire-prone vegetation, a very important element is the size of the fire load on the indicated plots. On representative plots, the biomass of the land cover was measured on an area of 10 m2 and then the amount of biomass of each component was determined. The resulting element of variability of ground covers in stands was their flammability classification. The classification developed made it possible to track changes in the flammability classes of stands over the period covered by the measurements.

Keywords: classification, combustible material, flammable vegetation, Norway spruce

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Authors: Neritan Shkodrani

Abstract:

On November 26, 2019, an earthquake hit the central western part of Albania. It was assessed as Mw 6.4. Its epicenter was located offshore north western Durrës, about 7 km north of the city. In this paper, the consequences of settlements of very soft soils have been discussed for the case of a residential building, mentioned as “K Building”, which was suffering a significant tilting after the earthquake. “KBuilding” is an RC framed building having 12+1 (basement) storiesand a floor area of 21000 m2. The construction of the building was completed in 2012. “KBuilding”, located in Durres city, suffered severe non-structural damage during November 26, 2019, Durrës Earthquake sequences. During the in-site inspections immediately after the earthquake, the general condition of the buildings, the presence of observable settlements on the ground, and the crack situation in the structure were determined, and damage inspection were performed. It was significant to note that the “K Building” presented tilting that might be attributed, as it was believed at the beginning, partially to the failure of the columns of the ground floor and partially to liquefaction phenomena, but it did not collapse. At the first moment was not clear if the foundation had a bearing capacity failure or the foundation failed because of the soil liquefaction. Geotechnical soil investigations by using CPTU test were executed, and their data are usedto evaluatebearing capacity, consolidation settlement of the mat foundation, and soil liquefaction since they were believed to be the main reasons of this building tilting.Geotechnical soil investigation consist in 5 (five) Static Cone Penetration tests with pore pressure measurement (piezocone test). They reached a penetration depth of 20.0 m to 30.0 mand, clearly shown the presence of very soft and organic soils in the soil profile of the site. Geotechnical CPT based analysis of bearing capacity, consolidation, and secondary settlement are applied, and results are reported for each test. These results shown very small values of allowable bearing capacity and very high values of consolidation and secondary settlements. Liquefaction analysis based on the data of CPTU tests and the characteristics of ground shaking of the mentioned earthquake has shown the possibility of liquefaction for some layers of the considered soil profile, but the estimated vertical settlements are at a small range and clearly shown that the main reason of the building tilting was not related to the consequences of liquefaction, but was an existing settlement caused from the applied bearing pressure of this building. All the CPTU tests were carried out on August 2021, almost two years after the November 26, 2019, Durrës Earthquake and when the building itself was demolished. After removing the mat foundation on September 2021, it was possible to carry out CPTU tests even on the footprint of the existing building, which made possible to observe the effects of long time applied of foundation bearing pressure to the consolidation on the considered soil profile.

Keywords: bearing capacity, cone penetration test, consolidation settlement, secondary settlement, soil liquefaction, etc

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