scholarly journals Tailings Dam Conceptual Design with Geomechanical Material Properties Approach to Determine Safety Criteria

2021 ◽  
Vol 1 (1) ◽  
pp. 368-377
Author(s):  
Oktarian Wisnu Lusantono ◽  
Aldin Ardian ◽  
Istifari Husna Rekinagara
Keyword(s):  
Conceptual Design ◽  
Quantitative Research ◽  
Physical And Mechanical Properties ◽  
International Standards ◽  
Tailings Dam ◽  
Geomechanical Properties ◽  
Material Condition ◽  
American Standard ◽  
Material Conditions

Geotechnical conditions as one of the conditions considered in the design and planning of tailings dams are strongly influenced by material conditions. The material condition is a parameter that will always be taken into account with stability. The material condition can be defined as a behavior that is based on the physical and mechanical properties of the material. By understanding the behavior of materials in a tailings dam construction, the risk of geotechnical failure can be controlled and minimized. This research was intended to study and investigate the behavior of material based on the geomechanical properties of the material used in a model. Generally, to determine the geomechanical properties of a material, several tests, both in-situ and laboratory tests, are required. Laboratory testing uses international standards such as ISRM (International Society of Rock Mechanics) and ASTM (American Standard Testing Materials). The research methodology used is descriptive quantitative research method. The studied parameter in this research is the geomechanical properties that influence the material on its conceptual design in terms of safety criteria (safety factor and probability of landslides) on the tailings dam embankment.

scholarly journals Sub-Level Stoping in an Underground Limestone Quarry: An Analysis of the State of Stress in an Evolutionary Scenario

2016 ◽  
Vol 61 (1) ◽  
pp. 199-216 ◽  
Author(s):  
Marilena Cardu ◽  
Sergio Dipietromaria ◽  
Pierpaolo Oreste
Keyword(s):  
Numerical Models ◽  
The State ◽  
In Situ Tests ◽  
Future Scenario ◽  
Limestone Quarry ◽  
Geomechanical Properties ◽  
State Of Stress ◽  
Upper Level ◽  
Pillar Structure

Abstract The aim of this study was to evaluate the state of stress of a „voids-pillar“ structure excavated by means of the sub-level stoping method in an underground limestone quarry near Bergamo (Italy). Both the current structure of the quarry (i.e. the rooms exploited till now) and a possible future scenario were analysed using the (FDM) FLAC 2D code. The quarry has been in operation since 1927; at present, exploitation is carried out underground via the sub-level stoping method. Exploitation involves two levels, with 5 rooms on the upper level and 9 rooms on the lower level. After analysing data obtained from laboratory and in situ tests carried out on rock samples and natural discontinuities, the geomechanical properties of the medium, knowledge of which is essential in order to establish the parameters that must be included in the numerical model, were evaluated. The implementation of three numerical models made it possible to study both the present conditions of quarry exploitation and the evolution of the exploited rooms, as well as a possible expansion involving a third level of rooms. Using the results obtained regarding the stress-strain present in the pillars, a potential change in room geometry was proposed aimed at reducing the stress state inside the pillars, decreasing plasticity and increasing overall quarry safety.

Effect of pouring temperature on A356-TiB2 MMCs cast in sand and permanent moulds by in-situ method

2016 ◽  
Vol 25 (5-6) ◽  
pp. 165-169
Author(s):  
C. Rajaravi ◽  
P.R. Lakshminarayanan
Keyword(s):  
Evaluation Studies ◽  
Physical And Mechanical Properties ◽  
Xrd Analysis ◽  
Matrix Composites ◽  
Structure Property ◽  
Pouring Temperature ◽  
Matrix Metal ◽  
Property Evaluation ◽  
The Matrix

AbstractThe paper describes a different condition of pouring temperature by sand and permanent mould to produce A356-6 wt% TiB2 metal matrix composites by in-situ method salt metal reaction route. The observation of SEM micrographs shows particle distribution of the TiB2 and it appears in hexagonal shape in Al matrix. The results of X-ray diffraction (XRD) analysis confirmed the formation of those TiB2 particulates and the results showed TiB2 particles are homogeneously dispersed throughout the matrix metal. Subsequent structure-property evaluation studies indicated sub-micron size reinforcement of in-situ formed TiB2 particles with improved physical and mechanical properties as compared to sand and permanent mould of Al-TiB2 composites. From, the permanent mould Al-TiB2 composite has an advantage of increase the properties over sand mould Al-TiB2 composite.

scholarly journals The Determinants of Audit Expectation Gap: An Empirical Study from Kingdom of Bahrain

2018 ◽  
Vol 7 (3) ◽  
pp. 54 ◽  
Author(s):  
Sayed Ali Ahmed Alawi ◽  
Rami Mohammad Abu Wadi ◽  
Gagan Kukreja
Keyword(s):  
Financial Reporting ◽  
Quantitative Research ◽  
Financial Statements ◽  
International Standards ◽  
Kingdom Of Saudi Arabia ◽  
The Public ◽  
Financial Reporting Standards ◽  
Expectation Gap ◽  
Audit Firms ◽  
National Bank

The research aims at identifying the determinants of audit expectation gap between the auditors and the users of financial statements in the Kingdom of Bahrain. This issue is noticed in many frauds or errors or illegal matters by the general public after every scam whether Enron and WorldCom from United States or Satyam and Punjab National Bank from India or Tesco and BHS from United Kingdom or Mobily from Kingdom of Saudi Arabia. As per International Standards on Auditing (ISAs), auditors are not responsible to detect each and every fraud or error or illegal act as it is the responsibility of management. However, auditors are expected to assess the possibility of an error or fraud to occur and assess risks of material misstatement due to error or fraud and they are supposed to express their independent and objective opinion on financial statements whether financial statements are prepared in accordance to suitable criteria (International Financial Reporting Standards in the case of Bahrain).This quantitative research and its descriptive design aims empirically to analyze determinants that may impact the audit expectation gap in the Kingdom of Bahrain. The study used a detailed questionnaire as a measuring instrument across the sample group to measure 4 determinants that are expected to have a significant impact on the level of the audit expectation gap. Those determinants are the efforts of auditors, the skills of auditors, the knowledge of the public about the audit profession and the users’ needs from auditors. The research inferred that identified factors found to have a significant impact on the level of audit expectation gap. It is recommended that audit firms should provide training to the audit staff that how to utilize the required efforts in conducting an audit engagement and go extra miles to fill the gap. Furthermore, the auditors should keep themselves updated about the latest frauds and the best audit practices. 

Hygrothermal Performance and Degradation of Gypsum Houses in Different Brazilian Climates

2015 ◽  
Vol 3 ◽  
pp. 137-149 ◽  
Author(s):  
R.M.S.F. Almeida ◽  
P. Paula ◽  
A. Santos ◽  
N.M.M. Ramos ◽  
J.M.P.Q. Delgado ◽  
...  
Keyword(s):  
Simulation Software ◽  
International Standards ◽  
Computer Simulation Model ◽  
Water Absorption Coefficient ◽  
Vapour Permeability ◽  
Climatic Regions ◽  
Hygrothermal Simulation ◽  
Durability Assessment ◽  
And Performance

This work consisted of two main lines of research: one of a literature review and other of simulation. In the first part, a modular constructive system based on gypsum blocks is presented. This constructive system reduces the manpower considerably, the time of execution and the final costs of construction. However, the durability assessment should be analysed but first its implementation and performance along the country must analysed.In this work a preliminary experimental characterization of the thermal conductivity, vapour permeability and water absorption coefficient of two different samples of gypsum plasters from the northeast Brazil (plaster pole of Araripe, Pernambuco) was performed. The experimental and analytical procedures followed either international standards or well-established methodologies, supporting the analysis of gypsum walls hygrothermal behaviour. The measured properties were adopted as inputs to hygrothermal simulation software and the analysis of gypsum based exterior walls was conducted for different climate zones and exposure conditions. The study demonstrates the durability issues that may arise in each location, due to differences in hygrothermal action.The other simulation part included hygrothermal advanced modelling, using the EnergyPlus software. The numerical results carried out allow a discussion over the interior comfort and durability of this modular constructive system. In this paper, the computer simulation model and the results of a parametric analysis of the dwelling performance on the eight climatic regions defined in Brazilian regulations are presented. The model was validated using the in situ measurements of air temperature.

Emissions and Noise Pollution Diagnosis of a Turbogas Power Plant During Commissioning Service

2010 ◽  
Author(s):  
Norberto Pe´rez Rodri´guez ◽  
Erik Rosado Tamariz ◽  
Rafael Garci´a Illescas
Keyword(s):  
Power Plant ◽  
Cooling System ◽  
Near Field ◽  
Noise Pollution ◽  
Point Of View ◽  
International Standards ◽  
Partial Load ◽  
The City ◽  
Permissible Deviation

This work is focused on the diagnosis of behavior, from the point of view of control emissions and noise level, of a power Turbogas plant during the process of commissioning, to guarantee that its operation complies with national and international standards. The environmental diagnosis of the power plant was developed as part of the performance evaluation of the unit. The conditions of the unit evaluation include operation at base load and partial load, as well as time periods for load changes. The evaluated power plant consists of an aeroderivative gas turbine installed in a simple cycle, operating with a cooling system (chiller) installed in the urban zone of Mexico City. Therefore, it should comply with the legislation and regulations of the city concerning air pollution and allowed noise, besides the international standards established by the manufacturer. The study includes emissions measurements using a Continuous Emissions Monitoring System installed in-situ, previously calibrated and checked during and after the test which was found inside the permissible deviation of 3%. Measurements were recorded at intervals of 5 minutes during test periods of 110 minutes for each load and 45 minutes for load changes. On the other hand, noise pressure evaluation was carried out in near field as well as far field produced by the power plant during operation. Measurements were carried out by using precision instruments installed specifically for it. A temporary system for obtaining data was used to monitoring the environmental conditions every 30 seconds. It was possible to verify that the turbogenerator complies with all noise levels and contaminant emissions requirements and regulations according to the limits established by the manufacturer and national and international standards.

scholarly journals MULTI-WAVE ULTRASONIC CONTROL OF CONCRETE

2017 ◽  
Vol 16 (4) ◽  
pp. 289-297
Author(s):  
D. Yu. Snezgkov ◽  
S. N. Leonovich
Keyword(s):  
Rayleigh Wave ◽  
Pulse Propagation ◽  
Ultrasonic Method ◽  
Physical And Mechanical Properties ◽  
Pulse Velocity ◽  
Energy Localization ◽  
Near Surface ◽  
In Situ Conditions ◽  
Selection Of

The existing non-destructive testing system of structure concrete is actually orientated on the usage of longitudinal acoustical waves. This is due to simplicity of technical realization for measuring velocity (time) of acoustical pulse propagation in bulk concrete. But a reverse side of simple measuring procedure is a loss of additional information on concrete which is contained in the accepted acoustical signal. Therefore usage of an ultrasonic concrete testing method is limited by assessment of its strength. Joint usage of several wave types, so-called multi-wave testing, allows to refine metrology parameters of the ultrasonic method and to gain more information while determining physical and mechanical properties of concrete in laboratory and in situ conditions. The paper considers testing of elongated concrete elements and structures by an ultrasonic pulsing method on the basis of longitudinal subsurface and Rayleigh waves. It has been proposed to use methodology for time selection of wave components according to amplitude parameter and it has been applied for standard acoustical transformers with considerable reverberation time and not possessing spatial selectivity Basic principle of the proposed methodology is visual (according to oscillogram of the received signal) determination of characteristic time moments which are used for calculation of differential value of a propagation velocity in the Rayleigh wave impulse. The paper presents results pertaining to simulation of acoustical pulse propagation on the basis of 0.15 m and data of concrete ultrasonic in situ testing on measuring bases from 0.25 to 1.75 m. Advantage of large baseline for sonic test is a possibility for execution of a hundred percent inspection for surface of large-sized elements and structures, and so there is no need to make a selective inspection in some control areas as it is stipulated by provided by existing regulations. Responsivity of the Rayleigh wave parameters to near surface concrete defects permits quickly and efficiently to detect crack areas in a reinforced structure. Energy localization of a surface wave in a layer having width λ/2–λ provides a possibility to ignore reinforcement availability under appropriate selection of oscillation frequency. In addition to this, large measuring baseline makes it possible to lower effect of concrete structural inhomogeneity on statistical stability for pulse velocity assessment that ultimately reveals a possibility to register an appearance of concrete acoustical elasticity effect under in situ conditions.

Weathering conditions of Buddhist caves dug in soft rocks and conservation attempting from the deterioration

2021 ◽  
Author(s):  
Chiaki Oguchi ◽  
Momoko Ogawa ◽  
Kaisei Sakane ◽  
Yasuhiko Tamura
Keyword(s):  
Environmental Monitoring ◽  
Layer Structure ◽  
Physical And Mechanical Properties ◽  
Small Scale ◽  
Central Japan ◽  
Soft Rocks ◽  
Geologic Materials ◽  
Temperature And Humidity ◽  
Non Destructive

<p>The Taya Cave, a sacred Buddhist cave, locates in the precincts of Josenji Temple in Yokohama City, central Japan. The geologic materials of the hills surrounding the cave are soft rocks composed of early Quaternary sedimentary rocks. The cave has a complex three-layer structure with a total length of 570 m. The excavation of the cave is estimated to start in the Kamakura era around A.D. 1200. Since then, the cave became a training place for Buddhists until around 19 C. There are many Buddhist reliefs on the walls and ceiling inside the cave. Because the bedrock is extremely weak, the rocks easily break when they get wet again after drying, namely prone to slaking. Thus, weathering and deterioration have progressed in various parts of the cave. Many valuable Buddhist reliefs have damaged by exfoliation. The walls at several points in the cave have also collapsed on a small scale. Therefore, it is necessary to investigate such deteriorated parts in the cave by simple non-destructive tests of physical and mechanical properties by using Silver Schmidt hammer and ultrasonic velocity test. These measurements clarified the vulnerable points even in the main worship route of the cave. In October 2018, a stainless-steel door installed at the cave entrance to save from deterioration due to slaking. The effect of the door was verified as well by monitoring the environmental conditions inside the cave. Environmental monitoring results revealed that the temperature and humidity near the entrance changed most drastically in this cave. Although the door was closed only at night, the range of maximum and minimum values ​​of temperature and humidity near the entrance became smaller after installation than before. Non-destructive measurements and in situ environmental monitoring are a useful way to assess weathering without damaging geoarchaeological sites. </p>

A Note on the Use of Preferred Number Series in Aircraft

1946 ◽  
Vol 50 (426) ◽  
pp. 416-420
Author(s):  
H. G. Conway
Keyword(s):  
International Standards ◽  
Aircraft Industry ◽  
Number Series ◽  
American Standard

The so-called Preferred or Standard Number Series is neither well-known nor often used in the British Aircraft Industry, perhaps because the series has not been published by the British Standards Institution or any other official body. Its use has much to commend it on the grounds of convenience and standardisation. Just as it is necessary for the international comprehension of science to standardise on basic symbols and terminology, so is it sometimes beneficial that numbers themselves should be widely used in the same manner.The Series is published in France as the Renard Series, and also by the International Standards Association, using rounded off numbers to suit the metric system. The American Standards Association has published an American Standard differing from the I.S.A. table only in so far as certain values are rounded off to reasonable inch figures; included also is a table of more approximate fractional sizes.

A Novel In-Situ Nanoindentation Characterization of Phase Transforming Materials

2015 ◽  
Vol 1754 ◽  
pp. 19-24
Author(s):  
A. Alipour Skandani ◽  
R. Ctvrtlik ◽  
M. Al-Haik
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Creep Compliance ◽  
Physical And Mechanical Properties ◽  
In Situ Methods ◽  
Negative Creep ◽  
Nanoindentation Instrument ◽  
Structural Instabilities

ABSTRACTMaterials with different allotropes can undergo one or more phase transformations based on the changes in the thermodynamic states. Each phase is stable in a certain temperature/pressure range and can possess different physical and mechanical properties compared to the other phases. The majority of material characterizations have been carried out for materials under equilibrium conditions where the material is stabilized in a certain phase and a lesser portion is devoted for onset of transformation. Alternatively, in situ measurements can be utilized to characterize materials while undergoing phase transformation. However, most of the in situ methods are aimed at measuring the physical properties such as dielectric constant, thermal/electrical conductivity and optical properties. Changes in material dimensions associated with phase transformation, makes direct measurement of the mechanical properties very challenging if not impossible. In this study a novel non-isothermal nanoindentation technique is introduced to directly measure the mechanical properties such as stiffness and creep compliance of a material at the phase transformation point. Single crystal ferroelectric triglycine sulfate (TGS) was synthetized and tested with this method using a temperature controlled nanoindentation instrument. The results reveal that the material, at the transformation point, exhibits structural instabilities such as negative stiffness and negative creep compliance which is in agreement with the findings of published works on the composites with ferroelectric inclusions.

scholarly journals Computer-Aided Material Design for Crash Boxes Made of High Manganese Steels

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 772 ◽  
Author(s):  
Angela Quadfasel ◽  
Marco Teller ◽  
Manjunatha Madivala ◽  
Christian Haase ◽  
Franz Roters ◽  
...  
Keyword(s):  
Sheet Thickness ◽  
Material Design ◽  
Tensile Tests ◽  
Material Strength ◽  
High Manganese ◽  
Material Efficiency ◽  
Material Condition ◽  
High Manganese Steels ◽  
Material Conditions ◽  
Manganese Steels

During the last decades, high manganese steels (HMnS) were considered as promising materials for crash-relevant automobile components due to their extraordinary energy absorption capability in tensile tests. However, in the case of a crash, the specific energy, absorbed by folding of a crash box, is lower for HMnS as compared to the dual phase steel DP800. This behavior is related to the fact that the crash box hardly takes advantage of the high plastic formability of a recrystallized HMnS during deformation. It was revealed that with the help of an alternative heat treatment after cold rolling, the strength of HMnS could be increased for low strains to achieve a crash behavior comparable to DP800. In this work, a multi-scale finite element simulation approach was used to analyze the crash behavior of different material conditions of an HMnS. The crash behavior was evaluated under consideration of material efficiency and passenger safety criteria to identify the ideal material condition and sheet thickness for crash absorption by folding. The proposed simulation methodology reduces the experimental time and effort for crash box design. As a result of increasing material strength, the simulation exhibits a possible weight reduction of the crash box, due to thickness reduction, up to 35%.

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