Search results

In literature, previous studies have focused on analyzing rienforced concrete (RC) columns with idealized end conditions when subjected to fire. In nature, full fixity or free rotation at column ends is not attained. Such ends may be considered partially restrained in rotation. This paper aims to shed a new light on the effect of different degrees of rotational restraint on the lateral deformation behavior of slender heated RC columns subjected to non-linear strain distributions produced by a time-dependent temperature history.

To find the strain distribution on the cross section, an iterative technique is adopted using Newton–Raphson method. By introducing a reliable calculation procedure, the lateral deformational behavior is expressed using numerical and searching techniques. A methodology is presented to calculate the effective length factor for RC columns at elevated temperature.

The results of the proposed model showed good agreement with available experimental test results. It was also found that the variation of rotational end restraint level has a considerable effect on the lateral deformation behavior of heated slender RC columns. In addition, the effectiveness and the validity of an analytical model should be verified by simultaneously validating the axial and lateral deformations. Moreover, the effective length factor for heated column is higher than that for the corresponding column at ambient temperature.

This paper shows the impact of different boundary conditions on the behavior of heated slender RC columns. It suggests powerful techniques to determine the lateral deflection and the effective length factor at high temperatures.

In present research work, the effects of rotational speed, feed rate and vibration amplitude have been investigated during novel method of ultrasonic-assisted bone grinding. During dissection of tumors, firstly a bone flap is removed near the target region to create passage for grinding burr. During abrasion, heat is produced, which sometimes increases the temperature to unsafe levels. So, efforts have been made to limit the temperature below the threshold levels of osteonecrosis during bone grinding.

The temperature produced during osteotomy has been measured using infrared thermography camera during the implementation of L18 Taguchi orthogonal array design. Subsequently, main effect plots and contour plots have been presented to analyze and visualize the effect of grinding parameters on temperature rise during bone grinding. Furthermore, the process parameters have been optimized for optimum results for response characteristics using Taguchi SN ratio-based optimization methodology. For multiobjective optimization, the process parameters are further optimized using grey relational analysis.

It is revealed that all three process parameters substantially affect the response characteristics. The proposed optimization methodology is successfully applied on the experimental findings and the optimum results for change in temperature are found to be rotational speed = 3,000 rpm, feed rate = 20 mm/min, amplitude = 10 µm and for standard deviation are 5,000 rpm, 60 mm/min, 10 µm.

The present research findings cannot be generalized, and researchers are encouraged to further investigate the proposed rotary ultrasonic-assisted bone grinding at higher rotational speed up to 60k rpm on the skull bone.

The research on osteotomy is still at its initial phase, and continuous research is carried out for making patients’ life comfortable. In this direction, the authors have proposed a novel osteotomy method to limit the temperature below the threshold limit of osteonecrosis. The outcomes of the present study will be beneficial for the neurosurgeons working in this field.

This paper aims to define and describe test methods and metrics to assess industrial robot system agility in both simulation and in reality.

The paper describes test methods and associated quantitative and qualitative metrics for assessing robot system efficiency and effectiveness, which can then be used for the assessment of system agility.

The paper describes how the test methods were implemented in a simulation environment and real-world environment. It also shows how the metrics are measured and assessed as they would be in a future competition.

The test methods described in this paper will push forward the state of the art in software agility for manufacturing robots, allowing small and medium manufacturers to better utilize robotic systems.

The paper fulfills the identified need for standard test methods to measure and allow for improvement in software agility for manufacturing robots.

The purpose of this paper is to describe a unique approach to investigate the wrinkle force of textile structures in a cylindrical model.

In this research, an apparatus was designed and constructed in order to investigate the torsional and wrinkle behavior of textile structures in a cylindrical model under a different rotational level using data acquisition and micro‐controller systems.

In the light of research results, the fiber and fabric type, fabric physical and mechanical properties and imposed rotational level significantly contributed to wrinkle characteristics of worsted fabrics. It was noticed that with increase of rotational level, the wrinkle force, and energy increased along weft and warp directions. Wrinkle characteristics along warp direction exhibited greater values than in weft direction.

The study is aimed at determining wrinkle behavior of worsted fabrics under the combined influences of compression and torsional strains.

This article examines the influence of centrifugal buoyancy on the hydrodynamic and thermal behaviour in fully developed flow through an orthogonally rotating duct of aspect ratio 2:1. A series of computations have been performed at rotation numbers ranging from 0 to 0.2, for constant‐density flows (no buoyancy) and also for different levels of outward and inward buoyancy. The resulting comparisons reveal that for a Reynolds number of 32,500, rotational buoyancy effects become significant at Rayleigh number values greater than 107. In outward flows, buoyancy is found to strengthen the effects of the Coriolis force on the mean motion and, by raising turbulence levels, buoyancy also enhances wall heat transfer along both the pressure and the suction side of the rotating duct. In inward flows, it is found that strong buoyancy can reverse the direction of the Coriolis‐induced secondary motion, which causes a strong rise in wall heat transfer along the suction side and a similarly significant fall in heat transfer along the pressure side. The computed effects on heat transfer are in qualitative agreement with the findings of a number of experimental studies. For both inward and outward flows, at a constant Reynolds number, the modifications of centrifugal buoyancy on the side‐averaged levels of heat transfer correlate reasonably well with the rotational Rayleigh number.

The purpose of this paper is to explore engagement of flexpatriates on rotational and regular field assignments in the energy industry, theoretically grounded in the “Four Fundamental Pillars of Engagement”.

In an exploratory case study within a global organisation in the energy industry, in a post-merger/acquisition integration stage, the authors interviewed 24 rotational and regular field assignees of seven different nationalities, residing at nine different global locations.

The results of the case study show that the following newly identified drivers within the “Four Fundamental Pillars of Engagement” are crucial for engagement of flexpatriate rotational and regular field assignees in the energy industry: information, communication and technology; training, learning and growth; support from colleagues and line managers (“capacity to engage”); job ownership/control; respect, recognition and appreciation (“reason to engage”); freedom to be creative and innovative; pride and promises; client satisfaction (“freedom to engage”); alignment between the organisation and the individual (“alignment to engage”), especially in a post-merger and acquisition (M&A) organisational context during a downturn in the oil and gas industry.

The case study focused on rotational assignees from one particular organisation in the energy industry, which restricts the generalisability of the findings on engagement of rotational assignees to other organisations, industries and geographies.

Organisations in the energy industry that actively promote engagement of rotational assignees, especially during the post-M&A integration stage and economic turmoil, will strengthen their sustainable global competitive advantage.

The contribution of this paper is that it presents a refinement and expansion of the drivers of engagement within the “Four Fundamental Pillars of Engagement”, conceptualised in an international post-M&A organisational context during a downturn in the oil and gas industry.

The main purpose of the present work is to study the multi response optimization of dissimilar friction stir welding (FSW) process parameters using Taguchi-based grey relational analysis and desirability function approach (DFA).

The welded sheets were fabricated as per Taguchi orthogonal array design. The effects of tool rotational speed, transverse speed and tool tilt angle process parameters on ultimate tensile strength and hardness were analyzed using grey relational analysis, and DFA and optimum parameters combination was determined.

The tensile strength and hardness values were evaluated from the welded joints. The optimum values of process parameters were estimated through grey relational analysis and DFA methods. Similar kind of optimum levels of process parameters were obtained through two optimization approaches as tool rotational speed of 1150 rpm, transverse speed of 24 mm/min and tool tilt angle of 2° are the best process parameters combination for maximizing both the tensile strength and hardness. Through these studies, it was confirmed that grey relational analysis and DFA methods can be used to find the multi response optimum values of FSW process parameters.

In the present study, the FSW is performed with L9 orthogonal array design with three process parameters such as tool rotational speed, transverse speed and tilt angle and three levels.

Aluminium alloys are widely using in automotive and aerospace industries due to holding a high strength to weight property.

Very limited work had been carried out on multi objective optimization techniques such as grey relational analysis and DFA on friction stir welded joints made with dissimilar aluminium alloys sheets.

The purpose of this paper is to present experimental studies on the designed muffler which contains ceramic foam and has the integration function of purification and noise elimination.

Comparative tests were done on a diesel engine with no muffler, the original muffler and the purification muffler. The soot index (light absorption coefficient), A-weighted sound pressure level and fuel consumption rate, which were collected by the partial flow opacity method, the insertion loss measurement of spatial five points and the load characteristics tests, respectively, and the effects of purification and noise elimination were studied.

The results of this paper state that the purification muffler shows great improvement on exhaust soot purification and noise elimination. The variation in diesel fuel consumption rate was small, the sound pressure level of purification muffler was reduced by 6 to 10 dB, the insertion loss of the purification muffler was increased by 6.41 dB and the average light absorption coefficient decreased by 57.8 percent compared with the original muffler.

The value of this study is that it supplies a purification muffler which contains a ceramic foam. Under the prerequisite of little effect on the fuel economy of diesel engine, the purification muffler shows great improvement in exhaust soot purification and noise elimination.

This paper is mainly aimed at the structural performance of compound cold-formed galvanised steel beams under fire conditions based on the results of a large programme of experimental tests and numerical simulations. The main objective of this research was to assess the critical temperature and time of the studied beams. Other important goals of this research work were to investigate the influence of the cross-sections (C, lipped-I, R and 2R beams) and, above all, of the axial restraint (0, 0.45, 3, 7.5, 15, 30, ∞ kN/mm) to the thermal elongation of the beam and the rotational restraint at beam supports (0, 15, 80, 150, 300, 1,200 and ∞ kN.m/rad) on the fire resistance of this kind of beams.

This paper still provides details of the simulation methodology for achieving numerical stability and faithful representation of detailed structural behaviour and compares the simulation and experimental results, including beam failure modes, measured beam axial forces and beam mid-span deflections.

Good agreement between Abaqus simulations and experimental observations confirms that the finite element models developed with the Abaqus/standard solver are suitable for predicting the structural fire behaviour of restrained cold-formed steel beams.

The results showed above all that the effect of the stiffness of the surrounding structure seems to decrease with the increasing slenderness of the beams.

The purpose of this paper is to define the relationships between the structure of multi-thread fancy yarns and the combination of the rotational speed of the hollow-spindle spinning system and thickness and stiffness of the effect component.

To do so, two groups of fancy yarns were made using stiff and soft effect threads and at six different machine settings.

It was found that the stiff effect thread was suitable to make fancy yarns at low rotational speeds, while the thickness of the effect threads was more important than its stiffness at low number of wraps. Additionally, even when using the same number of wraps and the overfeed ratio, a bouclé yarn, a gimp yarn, a wavy yarn or a loop yarn may results if the thickness and stiffness of the effect thread and the rotational speed were all controlled properly.

This study helps fancy yarn spinners to determine the type of final fancy yarns by controlling the spinning geometry in the first spinning zone.