Applied Mechanics and Materials Vol. 897

Abstract: . Elastics, a source of continuous orthodontic force, are divided into two types, latex and non-latex, which are made from natural rubber and synthetic rubber, respectively. The major advantage of natural latex elastics is its resiliency to intraoral tractive forces. However, as the incidence of allergic reactions to natural latex has become more widely recognized, non-latex orthodontic elastics have been developed as an alternative. The aim of this study is to investigate the in vitro mechanical properties of Thai non-latex orthodontic elastics as compared to commercially available products. 30 samples of each two Thai non-latex elastics (MTEC1, MTEC2) and two commercial elastics (AO, GAC) with a specified diameter of ¼ inches were used. Width, cross-sectional thickness (CT), and internal diameter (ID) of all samples were measured. Mechanical tests were then carried out to determine the initial extension force (F0), 24-hour residual force (F24), and percentage of force decay. The data were analyzed with one-way ANOVA and Tukey’s test (p < 0.05). Statistically significant differences in elastic width among all four groups except between the Thai non-latex groups (MTEC1 and MTEC2) were found. AO elastics showed the greatest CT followed by GAC, MTEC2 and MTEC1. ID was significantly highest in GAC elastics and lowest in MTEC1 elastics. Although MTEC1 elastics had the lowest F0, the force still falls within the acceptable range for tooth movement (100-250g or 0.981–1.471N). MTEC2 elastics had the greatest F24 and also the lowest percentage of force decay followed by MTEC1, GAC, and AO elastics, which displayed the highest force decay, though no significant differences were found between the two commercial elastics. Thai non-latex elastics are suitable for orthodontic tooth movement due to its lower percentage of force decay after 24 hours.

Abstract: Diagnostics of the rotor blades of aircraft gas turbine engines at pre-operational stage and later on during repairs is carried out by instrumental methods of non-destructive testing. The requirements for increasing operational reliability and safety of flights require a search for new solutions in assessing the strength of rotor blades at an early stage of damage development. For these purposes, one of the perspective directions is the development of acoustic emission methods. This article represents an experimental setup and a measuring-diagnostic system for assessing the operational reliability of rotor blades by the acoustic emission method. It also discusses the results of testing.

Abstract: In this paper, we consider a computational algorithm that allows us to follow specific sequences in order to meet the needs of the population in a residential area. As an integral indicator, the degree of satisfaction of the needs of the population is used, which characterizes the actual level of consumption of any services in comparison with the norm of their rational consumption. The theoretical premise of the study was the fundamental principle of urban development of a favorable environment for human development. The methodological basis of the study was a vector representation of the state of the system.

Abstract: Currently, theoretical and experimental studies on the overall behavior of semi-precast reinforced concrete high-rise buildings subjected to the earthquake are limited. These studies have mostly focused on the behavior of either joints or frames. To study the overall behavior of a structure under an earthquake, one of the best methods is to do the seismic shaking table test. This paper presents the results of an experimental study on the overall behavior of a semi-precast reinforced concrete multi-story building, which uses new design and construction technology, by using the seismic shaking table test method. These buildings are constructing in series in Vietnam. This research carried out both the linear and nonlinear behavior of the structure until the stage of near collapse. The study consists of three main steps: designing the simulating model; establishing a process to generate artificial accelerograms which are in accordance with the seismic characteristics in Vietnam; testing the 12-story semi-precast model to verify theoretical predictions.

Abstract: This paper presents the method of establishing artificial accelerogram for analysis and calculation of structures in accordance with seismic characteristics and earthquake risk in one specific construction areas in Vietnam. The artificial accelerogram allow to analyze nonlinear or linear dynamic behavior of the structures in time series in accordance with Vietnam National Standards for Design of structures for earthquake resistances (TCVN 9386: 2012) and seismic parameters specified in Vietnam Building Code on Natural Physical and Climatic Data for Construction (QCVN 02:2009-BXD). The accelerograms are also used as input parameters for shaking table tests by Vietnam's most modern sharking table at the Vietnam Institute for Building Science and Technology.

Abstract: This study used 700 children under the age of 11 as the research target for materials science introduces disaster prevention and mitigation education. The purpose of this study is to training and popularize the scientific knowledge literacy of disaster prevention, and to design disaster prevention and mitigation education through the diversity of material science. This study will carry out the learning outcome experiment of scientific concept and spontaneous concept into the disaster prevention science popularization education. Hope to study through teacher training courses, life science practice activities and digital learning application experiments. The study integrates material science disaster prevention course and campus science education, and 15 material science experiments were planned to be applied to the evaluation of the learning outcome of disaster prevention and mitigation experiments. Before the experiment, teachers were guided by disaster prevention science education, and after 12-year-old children relayed the principles of science, they assisted 6 to 11-year-old students to operate materials science experiments and analyze the learning outcome. Through simple teaching design and multi-level pre-teaching can effective promotion 36.5% of student's interest in material science used in the field of disaster prevention and mitigation, and by 73% of student aged 9 to 11, they can be more effectively improved the strategy and purpose of disaster prevention and mitigation education by dictation of their disaster prevention and mitigation education related to family, peers and living environment.

Abstract: Lightweight steel structure buildings are a special type of illegal building in Taiwan. There are many different types of these illegal structures in Taiwan used for various purposes. The number of factories operating in one of these illegal lightweight steel buildings alone is as high as 130,000 according to the 2017 statistics. The construction of such structures is easy, fast, and the cost is low, which is why they are widely accepted by the people.[1] The materials of a lightweight steel structure are mostly steel or C-shaped steel. When this type of steel structure is exposed to temperatures above 600 °C, the structure will begin to break and bend, causing deformation and eventually collapse. Additionally, the rapid growth of the fire, the lack of establishment on fire zones, and a fierce fire, etc., all present more challenges for onsite employees to extinguish the initial fires as well as the later fire rescue attempt by firefighters. In recent years, fatal fire incidents have been rampant, causing deaths and injury to foreign workers, highlighting fire safety issues. Therefore, “whether worker accommodation should be separated from the factory” is the subject of this paper. This study is aimed at the statistical survey of lightweight steel structures for industrial and residential use (current status): using data from project investigations to present the site overview and hazard risk factors. Risk assessment for buildings with accommodation inside the factory (validation): through the statistical survey data (34 of the 188 surveyed have accommodations inside the factory, a ratio of 18.1%), the hazard risk is assessed, and the potential risks are analyzed. Fire simulation on buildings with accommodation inside the factory (hazard): use fire simulation to analyze the effective evacuation time with residential fire alarms. To develop a disaster reduction strategy based on the results of the parametric analysis of this study for buildings with accommodation inside the factory (improvement): utilizing factory fire prevention analysis, factory symposium, fire prevention announcement, fire equipment inspection and maintenance, etc., to achieve disaster reduction. Based on the results of the parametric analysis of this study, we will develop an accommodation and disaster reduction strategy (improvement): use plant fire prevention diagnosis, factory symposium, fire prevention announcement, fire equipment inspection and maintenance, etc., to achieve disaster reduction.

Abstract: Underground pipeline systems in Thailand have been used for a long time. Lack of maintenances and longtime using cause a lot of damages. The water distribution systems are affected by the quality of water from contaminations and the quantity of water from leaking. As well as the sewer systems may flow through and contaminate the groundwater. Due to the long period of time of using underground pipeline systems, the verification of the underground location is need before testing the conditions of the systems with undisturbed area methods. This study focuses on the collection of the underground utilities locating methods and the conditions assessment methods. We also apply one suitable method for our case study area which is Nakhon Pathom province, Thailand. The results show the collection of methods to verify the underground location and conditions systems as well as the advantages and disadvantages of each method. Results also describe about conventional CCTV with push-rod camera for assessing underground pipeline systems for Nakhon Pathom province and the locations verification is fitted with ground penetrating radar, infrared thermography and acoustic location system. The design of a mobile robot to be flexible according to the pipe size and the creation of a computer program that can analyze the most suitable methods for examining buried pipes is a good option for further expansion in the future.

Abstract: . Landuse changing along the Bidara Cina, downstream of the Ciliwung floodplain deteriorates its environmental quality. Its interactions between the building along the floodplain and the river dynamics can be simulated with Ansys Fluent as a simulation tool. This tool simulates the impact of floods could damage the buildings structure that built in flood zones but are still within the limits of habitable zone permits. Ansys Fluent modelling is using CFD parameters, by creating geometric scenarios that have been physically tested. The geometric behavior observed through the effect of large window openings (Experiment x), namely model 1 with one window and model 2 with 2 windows, then it is analysed by rotating 0°, 30°, 45°, 60° and 90° of the building (Experiment y). The outputs that will be analyse from flood induced the building are (i) flood impact force, (ii) total force of building, and (iii) reduction of flow velocity in building. From the simulation result, it is found that building geometry with larger openings is better at resisting the impact strength of floods and reducing the velocity of flood flows. Furthermore, the graph of flood impact force and the total force of orientation in model 1 and model 2 have a tedency to increase while rotation angle increasing. We conclude that based on building type (Experiment x), the model with one window is most vulnerable model and based on building orientation (Experiment y), the model with orientation 90° is the most vulnerable model, but when viewed based on facade that is exposed to the main stream there is an opening, the orientation of 60° is the most vulnerable model.

Abstract: Sustainable procurement has been considered an opportunity for improving the environmental performance of the construction industry. The development of sustainable procurement in Indonesia is still in its initial phase. Therefore, a framework is needed to establish an outlook to explore the enablers and barriers for promoting sustainable procurement in the construction industry. In the formulation of the framework, the first step is to identify the important elements. The approach was explorative-descriptive. Based on ISO 20400, as the guidelines for sustainable procurement, and literature on sustainable procurement for construction works, a list of elements was gathered. In-depth interviews were conducted to identify the most significant elements for the Indonesian construction public procurement context. Respondents included procurement experts from the government agency, (i.e., the National Public Procurement Agency and the Ministry of Public Works and Housing), academics, and procurement specialists who are the members of the Indonesian Procurement Professionals Association. Results suggest that all elements contained in ISO 20400 are relevant with the kinds of literature on construction works; also, Indonesian respondents agreed with all the identified elements ranging from “important” to “very important.” This finding will be subsequently used to further understand the complex cause-effect relationships among the important elements in developing the framework for sustainable construction public procurement.