Bilingual Publishing Co. (BPC): E-Journals
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Effects of Different Cations on the Flocculation and Sedimentation of Static Fine-Grained Sediments
No full textNatural water bodies mostly contain cations, and the type and content of these cations are the main factors affecting the flocculation of fine-grained cohesive sediments and the floc sedimentation rate at the interface between clear and turbid water. From the microscopic aspect, this study examined the changing patterns of porosity and the fractal dimension of the flocs of fine-grained cohesive sediments. Sedimentation experiments under different sediment contents and electrolyte conditions were conducted, and microscopic images of the flocs were analysed using Image-Pro Plus (IPP) and MATLAB based on the fractal theory. From the macroscopic aspect, this study experimentally investigated the flocculation and sedimentation of fine-grained cohesive sediments and proposed a sedimentation rate equation by introducing an ion concentration-related parameter into an existing sedimentation rate equation (stagnation zone) based on the adsorption isotherm equation. The equation proposed in this study was validated with measured data. The calculated values were in good agreement with the measured values, with a relative error of 16%. The findings of this study provide a reference for further research on the flocculation and sedimentation of fine-grained cohesive sediments in different water bodies
A Comparative Study on Seismic Analysis of Multistorey Buildings in Different Seismic Zones
No full textThe multi-story buildings are constructed to accommodate numerous residents in confined spaces due to the growing population and lack of available land. The population growth and industrial revolution caused a migration of people from rural to urban areas resulting in the need for the construction of multi-story buildings for both residential and commercial uses. The tall buildings, which are not adequately constructed to resist lateral stresses, result in the total collapse of the structure. Buildings that can withstand earthquake forces are created by considering different criteria such as the building’s inherent frequency, damping factor, kind of base, significance of the building and ductility of the structure. Because they have better moment distribution properties, structures designed for ductility need to be designed for lower lateral loads. To ensure safety against the seismic stresses of multi-story buildings, it is essential to understand seismic analysis in order to develop earthquake-resistant structures. Both a regular moment resisting frame and a special moment-resisting frame were taken into account for the seismic study. In the present study, a G + 8 storey reinforced concrete (RC) structure in three different seismic zones was compared in terms of percentage longitudinal steel, reinforcement details, and design base shear. The structure was examined for seismic zones III, IV, and V in accordance with the guidelines of IS 1893 (Part 1): 2016. Results showed that base shear increased with the change in the seismic zone from III to V
Hysteretic Performance of Ring-shaped Energy-dissipating Devices for Assembly of Steel Frame Structure with External Wall Panel
No full textTo protect the external wall panel of the steel frame in prefabricated construction, a kind of ring-shaped energydissipating device (RSED) was proposed and further studied, which can connect the wall panel and steel frame. The hysteretic performance of steel frame-external wall panel system (SFEWPS) with RSED as the joint is analyzed via the finite element method, to quantify the protective effect of RSED on a wall panel. The results are that even under extremely rare earthquakes, RSED can still effectively control the energy consumption of wall panels, and play a protective role for it. In addition, combined with failure mechanism analysis, this paper proposes the best parameter selection for RSED
Environmental Impact Assessment of Building Materials Using Life Cycle Assessment
No full textIn pursuit of environmental sustainability in the construction sector, this study employs a comprehensive life cycle assessment (LCA) approach to evaluate the environmental impact of widely used building materials in Iran, with a particular focus on energy consumption and carbon footprint. The investigation encompasses 22 widely used building materials, utilizing the Ecoinvent v3 database and Simapro8 software to assess critical environmental variables, including carbon dioxide (CO2) emission, required primary energy, water consumption, and thermal conductivity. The findings unveil the diverse environmental profiles of these materials, with thermal conductivity typically hovering around zero to 2 W/m.K for most, but with exceptions such as lime, aluminum, rebar, and steel exhibiting significantly higher values. Moreover, aluminum, ceramics, PVC pipe, and expanded polystyrene (EPS) foam are identified as higher energy consumers during their life cycle, in contrast to concrete and cement mortar characterized by lower primary energy demands. The materials identified as high-carbon building materials are steel, stone, plaster, rebar, bitumen, concrete, glass, cement, gravel, and EPS foam. On the other hand, the materials identified as low-carbon building materials are masonry blocks, wood, tiles, bricks, drywall, MDF, and cement mortar. This research provides valuable insights for material selection and sustainable construction practices, emphasizing low-carbon materials to reduce environmental impact and contribute to the global effort to mitigate climate change through responsible construction choices
Cooperative Relaying in a Three User Downlink NOMA System Using Dynamic Power Allocation
No full textNon-orthogonal multiple access (NOMA) represents the latest addition to the array of multiple access techniques, enabling simultaneous servicing of multiple users within a singular resource block in terms of time, frequency, and code. A typical NOMA configuration comprises a base station along with proximate and distant users. The proximity users experience more favorable channel conditions in contrast to distant users, resulting in a compromised performance for the latter due to the less favorable channel conditions. When cooperative communication is integrated with NOMA, the overall system performance, including spectral efficiency and capacity, is further elevated. This study introduces a cooperative NOMA setup in the downlink, involving three users, and employs dynamic power allocation (DPA). Within this framework, User 2 acts as a relay, functioning under the decode-and-forward protocol, forwarding signals to both User 1 and User 3. This arrangement aims to bolster the performance of the user positioned farthest from the base station, who is adversely affected by weaker channel conditions. Theoretical and simulation outcomes reveal enhancements within the system’s performance
Changes in Subjective Sleep, Physical Condition, and Mental Health during the COVID-19 Pandemic: A Nationwide Survey in Japan
No full text This study aimed to investigate how people’s subjective health changed after the coronavirus disease 2019 (COVID-19) pandemic. This survey was conducted in May 2021 as a nationwide online self-reported survey in Japan. The respondents indicated how their sleep, physical condition, and mental state altered after the pandemic. Furthermore, they answered questionnaires about their intention to get vaccinated, the means of gathering information, etc. A logistic regression analysis was performed. Of the 2,573 responses, there was a decline of approximately 13.6%, 14.0%, and 23.8% in subjective sleep, physical condition, and mental health after the pandemic, respectively. The logistic regression analysis demonstrated that regarding sleep, the affected group was younger, got vaccinated against influenza annually, had lower income, experienced poor sleep quality in the past month, and had worse physical and psychiatric symptoms than before the pandemic. Concerning the physical condition, the affected group lived alone, witnessed deficient sleep quality in the past month, and had deteriorated mental health status than before the COVID-19 pandemic. In terms of mental status, the affected group was younger, females, had access to more sources of information, and experienced worse sleep and physical conditions than the unchanged or improved group (p < 0.05). Each group indicated an association with the background factors, confirming that the subjective sleep, physical condition, and mental state affected each other. From a preventive perspective, the results of this study suggested that factors such as youth, gender, sleep quality, pregnancy, reduced income, and greater access to information, may be necessary for physical and mental support. The above-mentioned factors should be considered in light of community life and approached accordingly
Retracted: Combined Effect of Thermal Shock and Hot Corrosion on the Failure of Yttria Stabilized Zirconia Thermal Barrier Coatings
No full textOwing to the authors' ignorance, a SEM picture (fig.3(d) in this paper) has been used in another paper (Fig.3(b) in a Chinese Journal). After carefully thinking, the authors decided to withdraw the paper with pity. This decision has been approved by both Editorial Office of JMMR and all authors. We apologize for the inconvenience may caused to readers.
Refers to original article：
https://doi.org/10.30564/jmmr.v1i1.307
Date of Retraction: July 10, 202
Understanding Applications and Best Practices of DEMATEL: A Method for Prioritizing Key Factors in Multi-Criteria Decision-Making
No full textDecision Making Trial and Evaluation Laboratory (DEMATEL) method is a powerful tool for understanding and visualizing the causal relationships among factors in complex decision-making problems. The method uses diagrams and matrixes to map out the causal relationships and interdependencies among factors, allowing decision-makers to identify key drivers and potential solutions to the problem. DEMATEL has a wide range of application areas, including supply chain management, environmental planning, healthcare, finance, and engineering, among others. The DEMATEL method is a valuable tool for decision-makers who need to understand the complex causal relationships among factors in order to make informed decisions. The method provides a structured approach for analyzing and prioritizing factors and for identifying potential solutions to complex problems. This paper describes the main features of this method, its application areas as well as the main process steps in the DEMATEL method
Green Walls as Mitigation of Urban Air Pollution: A Review of Their Effectiveness
No full textMitigation of urban air pollution has been constrained by the availability of urban spaces for greening. Green walls offer the prospect of greening spaces and surfaces without requiring large areas. Green walls can largely be divided into green facades where the aboveground parts of plants rooted in soil and pots grow directly on, and living walls holding bags, planter tiles, trays and vessels containing substrates in which plants are grown. Green facades and living walls can be continuous or modular with repeating units that can be assembled for extension. This review aims to present the effectiveness of green walls in removing different types of air pollutants in indoor and outdoor environments. It examined more than 45 peer-reviewed recently published scholarly articles to achieve the aim. It highlights that most of the studies on green walls focus on particulate matter removal and green walls could effectively remove particulate matter though the effectiveness varies with plant types, air humidity, rainfall and its intensity, leaf area index and contact angle, green wall surface coverage ratio, as well as the height of green walls. Increasing the height of green walls and optimizing their distance from roadsides could promote the deposition of particulate matter. Washing off could regenerate plant surfaces for capturing pollutants. Green walls are also effective in removing NO2, O3, SO2 and CO. Indoor active living walls, when properly designed, could have air purifying performance comparable to a HVAC system. The performance of green walls could be optimized through polycultures, selection of plants, surface coverage and height, and air inflow
Design of Multi-gas Monitoring Device for Indoor Air Quality
No full textBesides the need for low-cost instruments for air pollution measurement and detection, nowadays there are many concerns about air pollution due to the fast changes and used technologies. This research was applied using an MQ2 gas detector, and microcontroller/Arduino-Uno. The design steps included bonding and connecting readymade sensors, coding, and finally testing the device. Testing has been conducted in Environment and Pollution Engineering Department laboratories, at the Technical Engineering College of Kirkuk. This study proposed the use of an MQ2 sensor for multi-gas rate detection which can exist indoors. The system uses also a DHT22 sensor for measuring environment temperature and humidity. The sensors are connected to Arduino and LCD to present data on LCD by powering the system with external power. Overall, the testing was conducted, and the device served as a measuring tool for indoor air as an accurate multigas rate detector