scholarly journals Magnetic measurement system of sandy gravel specimens shape during tests in a large triaxial apparatus

2019 ◽  
Vol 92 ◽  
pp. 02004
Author(s):  
Roberta Ventini ◽  
Alessandro Flora ◽  
Stefania Lirer ◽  
Claudio Mancuso
Keyword(s):  
Relative Humidity ◽  
Mechanical Response ◽  
Magnetic Measurement ◽  
Triaxial Tests ◽  
Sandy Gravel ◽  
Partially Saturated ◽  
Triaxial Apparatus ◽  
Large Size ◽  
Size Of Particles ◽  
The University

As well known, rockfill behaviour is strongly influenced by both intrinsic (mineralogy and size of particles, grain shapes, soil grading etc.) and state parameters (relative density, stress state, relative humidity). To investigate their mechanical response to stresses and relative humidity (RH) loadings, a large size triaxial device (H = 410 mm, D = 200 mm) has been developed at the University of Naples Federico II (Italy), including modifications required to impose partially saturated conditions in the specimen by means of the vapour equilibrium technique. In order to evaluate local axial and radial strains and global volumetric strains in partially saturated conditions, a magnetic shape detector device has been designed and installed. The accuracy of this system has been evaluated in some isotropic compression triaxial tests on compacted sandy-gravel specimens. The experimental data clearly show the effectiveness of the magnetic system in the measurement of axial displacements while the measurement in radial direction appear to be strongly affected by the non-linearity of the complex magnetic field generated during the test and requires further checking tests.

scholarly journals 15. Clicker Lessons: Assessing and Addressing Student Responses to Audience Response Systems

2011 ◽  
Vol 1 ◽  
pp. 85
Author(s):  
Tim Pelton ◽  
Leslee Francis Pelton ◽  
Mary Sanseverino
Keyword(s):  
Audience Response ◽  
Evaluation Tool ◽  
Audience Response Systems ◽  
Self Evaluation ◽  
Perceived Need ◽  
Large Size ◽  
Response Systems ◽  
Support Teacher ◽  
The University ◽  
The Impact

This project began in response to a perceived need to assess students’ perceptions with respect to the emerging use of audience response systems (clickers) in several mid- to large-size undergraduate courses at the University of Victoria. We developed and validated a “Clicker Use Survey” to gather students’ opinions with respect to clicker utility and the impact of clicker use on their learning. With the collected data we generated a set of baseline distributions to support assessment of various clicker use protocols and created a self-evaluation tool to share with instructors to support teacher reflection on the efficacy of their clicker practices. We also provided a sample self-evaluation to model the use of the tool. Links to the survey instrument, baseline data and self-evaluation tool, and sample self-evaluation are provided.

scholarly journals Spring Deformation Gauge for Measuring Local Deformations in Triaxial Apparatus

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Mostafa A. Ismail ◽  
Yasser E. Ibrahim
Keyword(s):  
Accurate Determination ◽  
Cost Effective ◽  
Local Deformation ◽  
Spring Steel ◽  
Metal Strip ◽  
Triaxial Tests ◽  
Strain Gauges ◽  
Soil Stiffness ◽  
Triaxial Apparatus ◽  
Measured Deformation

Local measurement of deformations of a soil specimen has become inevitable for accurate determination of soil stiffness in triaxial tests. Although there are now many devices that can be used to perform this task, each has its own advantages and limitations that render development of new devices with better desirable features. This paper presents an innovative device called spring deformation gauge (SDG) that has many advantages over many of the existing devices and can be readily manufactured in both research and commercial laboratories. The device is based on using a highly flexible, yet very strong metal strip of spring steel secured between two stiff, stainless steel L-shaped legs; the spring strip is provided with four strain gauges. With this arrangement, local deformation of a specimen is transferred into significant bending in the metal strip and elongation or shortening of the strain gauges. In addition to being very cost effective, the SDG is characterized by the ability to control both range and resolution of measured deformation, its linear output, and a clever pinning mechanism that protects it from being damaged when it goes out of range. Success of the SDG was demonstrated in a true K0 test on carbonate sand.

scholarly journals Experimental Dynamic Analysis on a T100 Microturbine Connected With Different Volume Sizes

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
M. L. Ferrari ◽  
P. Silvestri ◽  
M. Pascenti ◽  
F. Reggio ◽  
A. F. Massardo
Keyword(s):  
Experimental Results ◽  
Test Rig ◽  
Large Size ◽  
Amplitude Increase ◽  
External Component ◽  
Compressor Map ◽  
Advanced Cycles ◽  
Valve Operation ◽  
The University ◽  
Volume Size

This paper shows experimental results obtained from a T100 microturbine connected with different volume sizes. The activity was carried out with the test rig developed at the University of Genoa for hybrid system emulation. However, these results apply to all the advanced cycles where a microturbine is connected with an additional external component responsible for volume size increase. Even if the tests were performed with a microturbine, similar analyses can be extended to large size turbines. A modular vessel was used to perform and to compare the tests with different volume sizes. To highlight the volume size effect, preliminary experimental results were carried out considering the transient response due to an on/off bleed valve operation. So, the main differences between system parameters obtained for a bleed line closing operation are compared considering three different volume sizes. The main results reported in this paper are related to surge operations. To produce surge conditions in this test rig, a valve operating in the main air path was closed to generate unstable behavior for the three different volume sizes. Particular focus was devoted to the operational curve plotted on the compressor map. The vibration frequency analysis showed significant amplitude increase not only during surge events but also close to the unstable condition. In details, possible surge precursor indicators were obtained to be used for the detection of risky machine operations. The experimental data collected during these tests are analyzed with the objective of designing control systems to prevent surge conditions.

scholarly journals Mechanical principles of nuclear shaping and positioning

2018 ◽  
Vol 217 (10) ◽  
pp. 3330-3342 ◽  
Author(s):  
Tanmay P. Lele ◽  
Richard B. Dickinson ◽  
Gregg G. Gundersen
Keyword(s):  
Nuclear Envelope ◽  
Mechanical Response ◽  
Mechanical Resistance ◽  
Nuclear Surface ◽  
Nuclear Movement ◽  
Large Size ◽  
Force Transfer ◽  
Nuclear Shaping ◽  
Resistance To Deformation ◽  
Cellular Forces

Positioning and shaping the nucleus represents a mechanical challenge for the migrating cell because of its large size and resistance to deformation. Cells shape and position the nucleus by transmitting forces from the cytoskeleton onto the nuclear surface. This force transfer can occur through specialized linkages between the nuclear envelope and the cytoskeleton. In response, the nucleus can deform and/or it can move. Nuclear movement will occur when there is a net differential in mechanical force across the nucleus, while nuclear deformation will occur when mechanical forces overcome the mechanical resistance of the various structures that comprise the nucleus. In this perspective, we review current literature on the sources and magnitude of cellular forces exerted on the nucleus, the nuclear envelope proteins involved in transferring cellular forces, and the contribution of different nuclear structural components to the mechanical response of the nucleus to these forces.

Seismic Testing of Eccentrically Braced Dual Steel Systems

1989 ◽  
Vol 5 (2) ◽  
pp. 429-449 ◽  
Author(s):  
Andrew S. Whittaker ◽  
Chia-Ming Uang ◽  
Vitelmo V. Bertero
Keyword(s):  
Building Research Institute ◽  
Large Size ◽  
Earthquake Simulator ◽  
Earthquake Resistant Design ◽  
Earthquake Resistant ◽  
Earthquake Research ◽  
Strength And Stiffness ◽  
Experimental Values ◽  
The University ◽  
The U.S

Two six-story eccentrically braced dual steel systems (EBDSs) were tested as part of the U.S.-Japan Cooperative Earthquake Research Program. The first, a full-scale structure ( prototype) was pseudo-dynamically tested in the Large Size Structures Laboratory of the Building Research Institute in Tsukuba, Japan. The second, a similitude scaled replica of the first, was tested on the earthquake simulator at the University of California at Berkeley. The prototype was designed for the minimum earthquake forces specified by the 1981 Japanese Aseismic Code and satisfied the current earthquake-resistant design regulations in the U.S.A. (1985 UBC, 1984 ATC 3-06 and 1986 SEAOC). The performance of the EBDS (both prototype and model) was outstanding in terms of its elastic strength and stiffnesses during minor earthquake shaking and its ability to absorb and dissipate energy, without strength and stiffness degradation, during severe earthquake shaking. Substantial overstrengths of both EBDSs with respect to their nominal yielding strengths were observed during severe earthquake shaking. However, the response modification factors currently adopted by the ATC and SEAOC significantly overestimated the experimental values in both instances.

Experimental behaviour and modelling of an unsaturated compacted soil

2000 ◽  
Vol 37 (4) ◽  
pp. 748-763 ◽  
Author(s):  
Celestino Rampino ◽  
Claudio Mancuso ◽  
Filippo Vinale
Keyword(s):  
Unsaturated Soils ◽  
Mechanical Response ◽  
Stress Path ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Experimental Program ◽  
State Variables ◽  
Soil Response ◽  
Optimum Water Content ◽  
Triaxial Cell

This paper reports the experimental study and modelling of the mechanical response of a silty sand used in the core of the Metramo dam, Italy. Specimens were prepared by compacting the soil at optimum water content conditions using the modified Proctor technique. Tests were performed under suction-controlled conditions by a stress path triaxial cell and an oedometer. The experimental program consists of 23 tests carried out in the suction range of 0-400 kPa. The findings indicate the strong influence of suction on compressibility, stiffness, and shear strength. The mechanical properties of the soil improve with suction following an exponential law with decreasing gradient. Furthermore, the soil exhibited collapsible behaviour upon wetting even at low stress levels. Interesting results were also achieved in elastoplastic modelling as well. The results led to characterization of soil behaviour with reference to widely accepted modelling criteria for unsaturated soils, providing noteworthy suggestions about their applicability for granular materials with a non-negligible fine component. Finally, some remarks are made for the extension under unsaturated conditions of the "Nor sand" model for saturated granular soils. The proposed approach yields improved predictions of deviator soil response of the tested soil when Cambridge-type frameworks prove invalid.Key words: unsaturated soils, stress state variables, triaxial tests, oedometer tests, constitutive model.

scholarly journals Analysing the Situation of ESL Teaching and Learning in Large University Classes in Pakistan

2020 ◽  
Vol 10 (5) ◽  
pp. 250
Author(s):  
Abdul Hameed Panhwar ◽  
Shah Nawaz Barich ◽  
Syed Khuram Shahzad
Keyword(s):  
Undergraduate Students ◽  
Teaching And Learning ◽  
English Language ◽  
Esl Teachers ◽  
Large Classes ◽  
Language Support ◽  
Teacher Student ◽  
Large Size ◽  
Teachers And Students ◽  
The University

The present study is based on a chapter of the PhD project conducted by the main researcher. It aims to explore the ESL teaching and learning practices in a Pakistani university by focusing on difficulties perceived and confronted by learners and teachers, and solutions suggested by them. One of the most significant issues at the university is large classes-exceeding to 100 and more students on average. The main researcher, being an ESL teacher at the target university, faced the same problem of large size and found it difficult to teach these classes. He embarked on analysing the situation so that he might come across some solutions through the suggestions and experiences of the ESL teachers and students of the same university. The design of the study is descriptive and the results of the present study come from the quantitative data collected through student and teacher questionnaires. The Student-participants were 300 undergraduate students from various major subjects attending English language support classes and 22 ESL teachers teaching these English language support classes at different institutes of the university. The data were analysed descriptively and presented with help of the boxplots. The views, commonly held by teachers are supported by the study’s findings i.e., large classes are likely to endorse teacher-centred approaches of teaching; very little significant student-student and teacher-student interaction is practised because of the inadequate physical environment; majority of learners remain off-task and appear to be unruly and they are given little, if any, feedback on their in-class and home tasks. Conversely, many teachers and learners reported that the adoption of group/pair work is likely to be an effective technique to use in these classes. Albeit a few teachers revealed having adopted group work infrequently, none used it all the time.

scholarly journals Requerimientos de humedad relativa y tiempos de incubación para la infección de conidios de Colletotrichum gloeosporioides en frutos de papaya.

2016 ◽  
Vol 9 (1) ◽  
pp. 81 ◽  
Author(s):  
Alfredo Durán ◽  
Lenín Ramírez ◽  
Dennis Mora
Keyword(s):  
Relative Humidity ◽  
Incubation Time ◽  
Initial Phase ◽  
Colletotrichum Gloeosporioides ◽  
Disease Incidence ◽  
Hot Water ◽  
Second Phase ◽  
Damage Level ◽  
The University ◽  
Erratic Behavior

The research was carried out at the University of Costa Rica's phytopathology laboratory between October 1995 and March 1996. In an initial phase, some creole papaya fruits from Gu.cimo (Limón province) were used. In order to eliminate latent infections, they were washed and immersed in hot water (49° C for 20 minutes). The fruits were then randomly placed in groups of 20, which conformed each treatment. Finally, they were inoculated by spraying with 5.5 ml of a 10.000 Colletotrichum gloeosporioides spores per mililiter suspension; then they were placed in plastic boxes and stored in containers with a 30°C temperature and relative humidities of 70%, 80%, and 90%. Fruits were kept in the compartments for periods of 5, l0, 15, 20 and 25 hours. Temperature and relative humidity were monitored during the experiment through the incubator's sensors and with a portable hydrothermograph. Finally, the incidence and severity of anthracnose was evaluated. During the second phase, fruits of the Hawaiian sunrise variety were used, following the same procedures applied to the native fruits. In native fruits, 100% of those placed at 80% and 90% relative humidity were contaminated after being in the compartment for five hours. The incidence decreased in the group with 70% relative humidity. The damage level increased with increases in relative humidity, although some erratic behavior was observed. In the test with Hawaiian fruit, the disease incidence increased according with incubation time. Severity showed a similar behavour; however, there was also erratic behavour here.

scholarly journals STUDI SIFAT MEKANIS TANAH MERAH DENGAN PENGUJIAN TRIAKSIAL

2018 ◽  
Vol 7 (1) ◽  
pp. 29-34
Author(s):  
Redaksi Tim Jurnal
Keyword(s):  
Shear Strength ◽  
Soil Type ◽  
Clay Soil ◽  
Soft Soil ◽  
Soft Clay ◽  
Liquid Limit ◽  
Red Soil ◽  
Triaxial Tests ◽  
Limit Value ◽  
Triaxial Apparatus

Characteristics soft soil can cause instability and long-term degradation problems. This is because the soil has a low shear strength value and high compressibility. One type of soil belonging to the soft soil type is soft clay soil. Red soil belongs to the soft clay soil type. Therefore, the purpose of this research to determines the parameters of the shear strength of red soil in the area of Pakjo City Palembang, South Sumatra Province. The equipment had been used to obtain parameters of mechanical properties of red soil was using Triaxial apparatus. The results of the red soil properties index include: water content value (□ 27.70%, specific gravity value (Gs) 2.67, liquid limit value (LL) 66.00%, value of plastic limit of 25.13% and index value (IP) of 40.87% Classification of soil CH (USCS) and A-7-6 (AASHTO). The result of the Triaxial tests was the value of cohesion (c): 16.25-18, 15 kPa, and internal friction (□): 13.50-14.75⁰. The result of shear strength (□) : 17.68-24.02 kPa. The shear strength value of red soil indicates soil which includes soft soil (12.5-25 kPa).

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