scholarly journals Gas Turbine Blade Damper Optimization Methodology

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
R. K. Giridhar ◽  
P. V. Ramaiah ◽  
G. Krishnaiah ◽  
S. G. Barad
Keyword(s):  
Gas Turbines ◽  
Normal Load ◽  
Phase 1 ◽  
Second Phase ◽  
Friction Damper ◽  
Friction Damping ◽  
Engine Order ◽  
Optimization Methodology ◽  
Model Tuning ◽  
Two Phases

The friction damping concept is widely used to reduce resonance stresses in gas turbines. A friction damper has been designed for high pressure turbine stage of a turbojet engine. The objective of this work is to find out effectiveness of the damper while minimizing resonant stresses for sixth and ninth engine order excitation of first flexure mode. This paper presents a methodology that combines three essential phases of friction damping optimization in turbo-machinery. The first phase is to develop an analytical model of blade damper system. The second phase is experimentation and model tuning necessary for response studies while the third phase is evaluating damper performance. The reduced model of blade is developed corresponding to the mode under investigation incorporating the friction damper then the simulations were carried out to arrive at an optimum design point of the damper. Bench tests were carried out in two phases. Phase-1 deals with characterization of the blade dynamically and the phase-2 deals with finding optimal normal load at which the blade resonating response is minimal for a given excitation. The test results are discussed, and are corroborated with simulated results, are in good agreement.

LinkedIn and recruitment: how profiles differ across occupations

2014 ◽  
Vol 36 (5) ◽  
pp. 583-604 ◽  
Author(s):  
Julie Zide ◽  
Ben Elman ◽  
Comila Shahani-Denning
Keyword(s):  
New York ◽  
Social Networking Sites ◽  
Personal Information ◽  
Phase 1 ◽  
Small Sample ◽  
Research Approach ◽  
Second Phase ◽  
Content Type ◽  
Two Phases ◽  
Group Member

Purpose – The purpose of this paper is to identify the elements of a LinkedIn profile that hiring professionals focus on most, and then examine LinkedIn profiles in terms of these identified elements across different industries. Design/methodology/approach – The methodology was comprised of two phases. In the first phase, researchers interviewed hiring professionals to determine their usage of LinkedIn. In the second phase, LinkedIn group member profiles from three industries – HR, sales/marketing and industrial/organizational (I/O) psychology – were compared on the 21 variables identified in Phase 1 (n=288). Findings – χ2 and ANOVA tests showed significant differences with respect to ten of the LinkedIn variables in how people presented themselves across the three groups. There were also several gender differences found. Research limitations/implications – A general limitation was the use of a qualitative research approach. A limitation of Phase 1 was that only a small sample of New York City-based hiring professionals was interviewed. Perhaps a wider, more diverse sample would have yielded different variables. In terms of Phase 2, it is possible that just utilizing the second connections of the researchers limited the generalizability of findings. Practical implications – User unwillingness to fully complete the LinkedIn profile suggests that it may not have replaced the traditional resume yet. Sales/marketing professionals were more likely than HR and I/O psychology professionals to complete multiple aspects of a LinkedIn profile. Women were also less likely than men to provide personal information on their profiles. Originality/value – Most of the empirical research on social networking sites has focussed on Facebook, a non-professional site. This is, from the knowledge, the first study that systematically examined the manner in which people present themselves on LinkedIn – the most popular professional site used by applicants and recruiters worldwide.

scholarly journals Hierarchical Multi-User Detection for Highly Overloaded Uplink Grant-Free NOMA

2021 ◽  
Author(s):  
Shah Mahdi Hasan ◽  
Kaushik Mahata ◽  
Md Mashud Hyder
Keyword(s):  
Phase 1 ◽  
Sparse Recovery ◽  
Second Phase ◽  
Sensing Matrix ◽  
Recovery Algorithm ◽  
Spreading Sequence ◽  
Active User ◽  
Machine Type Communication ◽  
Two Phases ◽  
Limited Spectrum

Grant-Free Non Orthogonal Multiple Access (NOMA) offers promising solutions to realize uplink (UL) massive Machine Type Communication (mMTC) using limited spectrum resources, while reducing signalling overhead. Because of the sparse, sporadic activities exhibited by the user equipments (UE), the active user detection (AUD) problem is often formulated as a compressive sensing problem. In line of that, greedy sparse recovery algorithms are spearheading the development of compressed sensing based multi-user detectors (CS-MUD). However, for a given number of resources, the performance of CS-MUD algorithms are fundamentally limited at higher overloading of NOMA. To circumvent this issue, in this work, we propose a two-stage hierarchical multi-user detection framework, where the UEs are randomly assigned to some pre-defined clusters. The active UEs split their data transmission frame into two phases. In the first phase an UE uses the sinusoidal spreading sequence (SS) of its cluster. In the second phase the UE uses its own unique random SS. At phase 1 of detection, the active clusters are detected, and a reduced sensing matrix is constructed. This matrix is used in Phase 2 to recover the active UE indices using some sparse recovery algorithm. Numerical investigations validate the efficacy of the proposed algorithm in highly overloaded scenarios.

scholarly journals Hospital mealtimes: action research for change?

2005 ◽  
Vol 64 (3) ◽  
pp. 269-275 ◽  
Author(s):  
Angela Dickinson ◽  
Carol Welch ◽  
Laurie Ager ◽  
Aileen Costar
Keyword(s):  
Action Research ◽  
Phase 1 ◽  
Hospital Setting ◽  
Phase Changes ◽  
Research Approach ◽  
Second Phase ◽  
Action Research Approach ◽  
Three Phase ◽  
Two Phases ◽  
Patients Experience

Poor nutritional care within the hospital setting continues despite decades of work chronicling and measuring the problems. To address the problem changes in practice have been attempted to improve the patients’ experience of mealtimes. In order to implement patient-centred mealtimes for older patients by changing the focus from institutional convenience to one that focuses on the requirements of the patients, an action research approach has been used that focuses on action and change, and thus appears to have much to offer those who seek to change practice. The present paper focuses on the first two phases in a three-phase approach. In phase one the nature of everyday mealtime care and the wider context are explored using focus groups, interviews and observations. The data fall into three main themes that all impact on patients’ experiences of mealtimes: institutional and organisational constraints; mealtime care and nursing priorities; eating environment. Following feedback of phase 1 findings to staff and identification of areas of concern a model of practice development was selected to guide the change process of the second phase. Changes to mealtime nursing practice and the ward environment have been made, indicating that action research has the potential to improve the mealtime care of patients.

scholarly journals Scientific Need for Space Astronomy

1980 ◽  
Vol 5 ◽  
pp. 63-68
Author(s):  
L. Goldberg
Keyword(s):  
High Altitude ◽  
Phase 1 ◽  
Satellite Orbit ◽  
Earth Satellite ◽  
Second Phase ◽  
National Academy Of Sciences ◽  
Space Astronomy ◽  
Small Satellites ◽  
Time Space ◽  
Two Phases

Many scientific justifications for space astronomy have been prepared by individuals and committees during the past three decades or more. The first such report that I am aware of, called “Astronomical Advantages of an Extraterrestrial Observatory”, was written by Lyman Spitzer in September 1946, and although its goals were extremely modest by today’s standards, the report did dwell with enthusiasm on the ultimate goal of a large reflecting telescope 4-6 meters in diameter with diffraction-limited optics put into earth-satellite orbit. The latest study, from which I shall quote liberally, has just been published by the Astronomy Committee of the U. S. National Academy of Sciences, and provides the scientific foundation for space astronomy in the 1980’s. Space Astronomy was initiated about one month after the date of publication of Spitzer’s report, when the first high-altitude rocket was launched to observe the sun’s ultraviolet radiation. Since that time, space astronomy has completed two phases and is about to embark on a third. In Phase 1, which lasted until the beginning of Sputnik, observations were made for a few minutes at a time from high-altitude rockets. In the second phase, which is just ending, observations were made with relatively small instruments in earth-orbiting satellites. The observing programs carried out with rockets and small satellites were called experiments because their capabilities and objectives were limited and their lifetimes were short -from a few minutes to about a year.

scholarly journals Hierarchical Multi-User Detection for Highly Overloaded Uplink Grant-Free NOMA

2021 ◽  
Author(s):  
Shah Mahdi Hasan ◽  
Kaushik Mahata ◽  
Md Mashud Hyder
Keyword(s):  
Phase 1 ◽  
Sparse Recovery ◽  
Second Phase ◽  
Sensing Matrix ◽  
Recovery Algorithm ◽  
Spreading Sequence ◽  
Active User ◽  
Machine Type Communication ◽  
Two Phases ◽  
Limited Spectrum

Grant-Free Non Orthogonal Multiple Access (NOMA) offers promising solutions to realize uplink (UL) massive Machine Type Communication (mMTC) using limited spectrum resources, while reducing signalling overhead. Because of the sparse, sporadic activities exhibited by the user equipments (UE), the active user detection (AUD) problem is often formulated as a compressive sensing problem. In line of that, greedy sparse recovery algorithms are spearheading the development of compressed sensing based multi-user detectors (CS-MUD). However, for a given number of resources, the performance of CS-MUD algorithms are fundamentally limited at higher overloading of NOMA. To circumvent this issue, in this work, we propose a two-stage hierarchical multi-user detection framework, where the UEs are randomly assigned to some pre-defined clusters. The active UEs split their data transmission frame into two phases. In the first phase an UE uses the sinusoidal spreading sequence (SS) of its cluster. In the second phase the UE uses its own unique random SS. At phase 1 of detection, the active clusters are detected, and a reduced sensing matrix is constructed. This matrix is used in Phase 2 to recover the active UE indices using some sparse recovery algorithm. Numerical investigations validate the efficacy of the proposed algorithm in highly overloaded scenarios.

scholarly journals Modification of Clays by Sol-Gel Reaction and Their Use in the EthyleneIn SituPolymerization for Obtaining Nanocomposites

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
E. Moncada ◽  
R. Quijada ◽  
P. Zapata
Keyword(s):  
Phase 1 ◽  
Sol Gel ◽  
Metallocene Catalyst ◽  
Polymerization Reaction ◽  
Second Phase ◽  
Clay Particles ◽  
Nanoparticle Morphology ◽  
Two Phases ◽  
Made In

The nanocomposites formation byin situpolymerization used a metallocene catalyst (butyl-2-cyclopentadienyl zirconium 2-chlorines) and a hectorite synthetic clay type which is discussed. This research was carried out in two phases. The first phase consisted of mixing the components of the metallocenic polymerization reaction (metallocene-methylaluminoxane-ethylene) with clay in a reactor. In the second phase, the metallocenic catalytic system was supported by clay particles and then a polymerization reaction was made. In this second phase, the clay particles were modified using a sol-gel reaction with different pH values: pH = 3, pH = 8, and pH = 12. The results were compared in terms of the catalytic activity in the different systems (phase 1 and phase 2) and the nanoparticle morphology of nanocomposites generated in this study.

Transformations of sulfur in soil and subsequent uptake by subterranean clover

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1207 ◽  
Author(s):  
GJ Blair ◽  
AR Till ◽  
CD Shedley
Keyword(s):  
Phase 1 ◽  
Subterranean Clover ◽  
Hydriodic Acid ◽  
Recycling Rate ◽  
Second Phase ◽  
Potential Contribution ◽  
Application Rates ◽  
Two Temperatures ◽  
Two Phases ◽  
Turn Over

For a soil test to be effective it must sample pools of sulfur (S) that are immediately available to the plant and organic pools that turn over rapidly and supply S in the longer term. An experiment was conducted in two phases, the first being over 96 days to study the incorporation of S from Na2 35SO4 into various soil components at two temperatures [18/11�C (day/night) and 27/22�C] and two S application rates (10 and 50 �g S g-1 soil) and its uptake by subclover grown in pots. At intervals the pots were destructively sampled and the components radioassayed. In the second phase, soil sulfate was removed from the soil used in the first phase and the soil was potted and replanted with subclover. Soil and plant samples were taken 70 days later and the plant uptake and recycling of S-35 from the labelled soil organic pools were measured. Within 14 days in phase 1, at least 40% of the applied 35S sulfate had been incorporated into the hydriodic acid-reducible (HI-S) fraction. Subsequently, the S in the newly formed H-S fraction was recycled with mean net release rates of 35S being 26% and 38% over the next 21 and 28 day periods respectively. The mean 35S content of the carbon bonded (C-S) fraction reached a peak of 22% after 63 days, indicating a very much slower recycling rate than the H-S fraction. These results show the importance of the HI-S fraction and stress that any reliable soil testing method must at least include some estimate of the potential contribution from the H-S fraction as well as the 'available' inorganic S.

New Modeling Combining Kinematic and Stiffness Nonlinearity in Under Platform Dampers

2021 ◽  
Author(s):  
Ryuichi Umehara ◽  
Sotaro Takei ◽  
Tomohiro Akaki ◽  
Hiroki Kitada
Keyword(s):  
Friction Coefficient ◽  
Gas Turbines ◽  
Normal Load ◽  
Contact Stiffness ◽  
Turbine Blades ◽  
Frequency Variation ◽  
Friction Damper ◽  
Nonlinear Characteristics ◽  
Friction Dampers ◽  
Geometric Nonlinear

Abstract Turbine blades are used under increasingly severe conditions in order to increase the thermal efficiency of the gas turbines in operation. Friction dampers are often used to reduce the vibration of the blade and improve the plant reliability. Under platform dampers designed to generate friction between platforms and dampers have been widely adopted in gas turbines as one of the friction dampers. It is important to predict the vibration characteristics of such damper blades analytically during the design phase, and many analysis methods have been proposed vigorously. However, the phenomenon of the friction damper is not fully understood because of its complicated behavior due to nonlinearity such as contact and sliding. One of them is the variability of frequency generated in the under platform dampers. Recently, it has been reported on the variability of frequency in the mock-up blade test greatly under small excitation force, due to variability of contact surfaces. As different approach, mechanism of the variability of frequency is explained even if each damper pin has the same dimensions and characteristics of stiffness each other under the range of small vibration without slipped phenomena. In this paper, the phenomenon of this frequency variation is shown based on two physical phenomena. First, it shows the geometric nonlinear characteristics in which the normal load changes by the friction coefficient of the pin and the pin angle. Second, it shows the stiffness nonlinear characteristics in which the contact stiffness changes with the normal load of the pin. Based on the new proposed modeling of combining the geometric nonlinear characteristics and nonlinear stiffness characteristics, the phenomenon is shown in which the relative displacement of the pin changes the load and contact stiffness, and the frequency changes. It also shows that the maximum normal load before sliding is different depending on the friction coefficient and the pin angle, and that when the friction coefficient is large and the damper angle is large, the change in contact stiffness due to the normal load is large and the variability of frequency is large.

The Development of Life and Career Skills in 21st Century Test for Undergraduate Students

2022 ◽  
Vol 11 (1) ◽  
pp. 51-68
Author(s):  
Nuanphan Chaiyama ◽  
Nimnoul Kaewpila
Keyword(s):  
Undergraduate Students ◽  
21St Century ◽  
Phase 1 ◽  
Second Phase ◽  
Eastern Region ◽  
Test Items ◽  
The North ◽  
North Eastern ◽  
Two Phases ◽  
Career Skills

<p style="text-align: justify;">The purposes of this study were to explore factors and indicators of life and career skills and to develop a life and career skills in the 21st century test for undergraduate students. This research employed a mixed-method study adopting an exploratory design: instrument development model to generate research tools. This study was divided into two phases; Phase 1 was to explore factors and indicators of life and career skills in 21st century, by using a qualitative method to analyze relevant documents; Phase 2 was the development of a life and career skills in 21st century test by adopting a quantitative method to collect data from students studying in 12 universities of the north-eastern region of Thailand via the test. In the second phase, the data were analyzed by descriptive statistics and Confirmatory Factor Analysis (CFA) Results revealed that the skills consisted of 6 factors and 35 indicators, and the test comprised 105 items. The quality of the test has been examined by five expertise, the reliability of all test items is acceptable, and all 6 factors demonstrated good construct validity. Factor loadings of six factors were 0.7940 -1.7816. This study can be implemented to measure the life and career skills of undergraduate students in any university to obtain data for establishing a policy and plans for maximizing students’ potential to achieve their careers and a happy living in 21st century after their graduation.</p>

scholarly journals La Gestion du Risque de Micro-crédit: La Nécessité du Diagnostic Financier: Cas de la PME MIGEG Microfinance S.A.

2017 ◽  
Vol 13 (19) ◽  
pp. 292
Author(s):  
Lucas Pony
Keyword(s):  
Quantitative Data ◽  
Phase 1 ◽  
The Other ◽  
Second Phase ◽  
Phase 2 ◽  
Financial Health ◽  
Financial Lever ◽  
Diagnosis Method ◽  
Two Phases ◽  
Gestion Du Risque

The reduction of the losses related to credit outstanding payment is very necessary in the micro finance institutions in general, and the SME of micro finance MIGEG* S.A in particular. Here, we carried out a study concerning the management of micro credits risk which result to losses due to non-refund. The method that was proposed in this study is that of the financial diagnosis which operates in two phases. The first phase involves the use of the data collected during the interview to analyze the morality of the customer (Phase 1), while the second phase involves the use of the financial and accounting quantitative data to analyze the financial health of the customer (Phase 2).The diagnosis method considered is that of Dupont which allows us to considerably reduce the percentage of credits outstanding payment. Consequently, it also helps to improve the company’s funds. The proposed method will help the managers to detect the risks of application for credit. The bank will thus grant only the credit bonds related to the highest refunds. This, however, will further lead to the following results: For MIGEG S.A to be viable, it must insist on the ratio of the assets. This refers to the sales of the credits to promote refunds without risk. On the other hand, MIGEG S.A will insist on the ratio of the financial lever, debt and assets, in order to promote the prefinancing of the risk credits. Therefore, it will help to avoid credits related to the guarantees such as the land certificate, inheritance etc.

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