Jamil Abdo

Nano-Enhanced Drilling Fluids: Pioneering Approach to Overcome Uncompromising Drilling Problems

The idea of pushing the limits of drilling oil and gas wells by improving drilling fluids for undemanding and cost efficient drilling operations by extracting advantage from the wonders of nanotechnology forms the basis of the work presented here. Foremost, in order to highlight the significance of reducing the size distribution of particles, new clay ATR which has a chain like structure and offers enormous surface area and increased reactivity was tested in different sizes that were chemically and mechanically milled. Bentonite which is a commonly used drilling fluid additive was also tested in different particle size distribution (PSD) and rheological properties were tested. Significant reduction in viscosity with small sized particles was recorded. The tested material called ATR throughout this paper is shown to offer better functionality than bentonite without the requirement of other expensive additives. Experiments were performed with different size distributions and compositions and drastic changes in rheological properties are observed. A detailed investigation of the shear thinning behavior was also carried out with ATR samples in order to confirm its functionality for eliminating the problem of mechanical and differential pipe sticking, while retaining suitable viscosity and density for avoidance of problems like lost circulation, poor hole cleaning and inappropriate operating hydrostatic pressures.

Modeling and control of two manipulators handling a flexible object

Manipulating flexible objects stirs a great deal of interest due to the potential applications in industry. Most previous research work with multiple manipulators, however, focused on developing control strategies for the manipulation of rigid bodies. This paper seeks to develop simple yet practical and efficient control scheme that enables cooperating arms to handle a flexible beam. Specifically the problem studied herein is that of two arms rigidly grasping a flexible beam and capable of generating forces/moments in such a way as to move a flexible beam along a predefined trajectory. The paper develops a sliding mode control law that provides robustness against model imperfection and uncertainty. It also provides an implicit stability proof. Given the bounds of uncertainty in the model of the flexible beam and choosing a switching surface that enforces trajectory tracking, a control algorithm is designed to push the states to remain on the switching surface. Simulation results for two three joint arms moving a flexible beam are presented to validate the theoretical results.

Experimental Technique to Study Tangential-to-Normal Contact Load Ratio

This paper considers the mechanical interaction due to surface roughness and examines the surface theories using the classical definition of coefficient of friction: the tangential-to-normal load ratio. The postulation for maximum static friction is used to experimentally evaluate the contact models. For this purpose, a pin-on-disk test apparatus is employed with the capability of measuring tangential and normal forces for a frictional contact. The tests involve pairs of disks and specimens, that is, steel-on-steel and aluminum-on-aluminum contacts. In each case, profilometer measurements are performed on the disk and the Greenwood and Williamson parameters, are determined. Using the parameters, the theoretical estimates of normal and tangential loads are obtained. The theoretical values of tangential-to-normal contact load ratios are compared with those obtained from measurements for various applied normal loads. The tests utilizing a pin-on-disk apparatus showed a partial agreement between the experimentally obtained load ratios and the predicted upper limit confidence interval using the theoretical elastic and elastic-plastic contact. The result suggested that the elastic-plastic formulations provide better predictions of load ratios than the elastic contact formulations.

Evaluation of Disc Brake Materials for Squeal Reduction

A nontraditional evaluation tool is introduced to examine the effects of different materials, in practical applications, that are used in fabricating disc brake components for commonly used or special requirements such as heavy-duty performance and racing cars. As an extension to earlier finite element (FE) disc brake models, a detailed FE model of the whole disc brake corner that incorporates the wheel hub and steering knuckle is developed and validated using experimental modal analysis. Stability analysis of the disc brake corner using the finite element software ABAQUS is carried out to predict squeal occurrence also taking into account the negative and positive damping effects and friction material real surface to increase the accuracy of prediction. A Taguchi method–based design of experiment is used to better assess the contributions of different materials and its interaction effects for effective reduction of brake squeal. The results showed that the pad friction material contributes 56% to the total system instability (squeal generation). The rotor material contributes 22% of the system instability. Caliper and bracket materials participate 11 and 11%, respectively.

The Effects of Demographic Factors on the Environmental Awareness of Omani Citizens

ABSTRACT In year 2007, a survey was conducted in the Sultanate of Oman in order to evaluate the current environmental awareness of the Omani general public and their willingness to protect the environment. The focus of the survey was to explore the role played by demographic factors (sex, age, and education level) in determining the environmental awareness of the Omani public. The survey was administered to 425 respondents among all areas of the entire Muscat governorate in Oman. The results of the survey revealed that the environmental awareness of the Omani public was related to gender, age, and education level. Males were found to have a higher level of knowledge about environmental issues than females. Males were also more environmentally concerned and tended to engage in more environmental behaviors than females. Younger and more educated respondents tended to be more knowledgeable and concerned about the environment than older and less educated respondents.

A study of the influence of brake pad topography on the generation of brake noise and vibration

The main objective of this study is to present the importance of considering the brake pad surface topography on predicting noise and vibration of braking system through finite element method (FEM). In this paper, a numerical analysis of disc brake squeal using a three-dimensional FE model of an actual disc brake system is presented. Firstly, the FE model is validated using the results of the parts and assembly’s FRF measurements, followed by using a complex eigenvalue analysis to assess the brake stability. Subsequently, the perfect and real surface topography of friction material are considered to examine its effect on squeal noise generation. As a result, it is observed that the real pad surface predicted less unstable frequencies than the perfect pad surface.

Materials sliding wear model based on energy dissipation

A mathematical model is developed to correlate the volumetric wear of materials with the dissipation energy in sliding contacts. In the analysis, the wear of contacting materials originating from the energy loss due to friction process in the contact is studied. Two mechanisms responsible for energy loss at contact are considered. The first is the amount of energy spent to import plastic deformation and the second is the elastic energy of the particulate. The energy loss due to elastic and plastic deformation is calculated. The statistical loss of energy is calculated for two rough surfaces by the assumption that there is negligible change in the statistical parameters of the surface during wear. The model can be useful to predict the service lifetime of components and eventually structures. The results showed that the amount of dissipated energy and the volumetric loss increased with increasing normal load. Also, changing the normal load changed the rate of energy dissipation per unit sliding distance.

The Effect of Controlled Frequency and Amplitude of Vibration on Friction

An in-house pin-on-disc apparatus is designed and constructed to perform the tests and the design of experiments technique is utilized to determine the effect of vibration, amplitude of vibration, surface roughness, and sliding speed and their cross influence on coefficient of friction for 304 stainless steel and Alloy 6061 Aluminum. The design is performed using response surface method (RSM). The coefficient of friction (CoF) is analyzed as a nonlinear function of the factors and predicted by a second-order polynomial equation. Results suggested that the presence of vibration affect the friction function CoF considerably for both metals. The friction function linearly decreases with the increases of vibration and amplitude of vibration, non-linearly decreases with the increases of sliding speed and linearly increases with the increases of the surface roughness until the middle range is reached and then there is non-linearly decrease thereafter. Similar trends of friction functions are observed for Alloy 6061 Aluminum with a reduction of almost 15% except for the case with amplitude of vibration where the variation showed more significant affect on the friction function when Alloy 6061 Aluminum disk is used.

An Eigenvalue Based Approach for Assessing the Decomposability of Interdependent Design Project Tasks

The Concurrent engineering process is characterized by executing a large number of interdependent project tasks. One effective way of managing such tasks is to decompose them into groups. However, not all tasks are decomposable. Without the need to apply a decomposition method, this paper describes a simple, quantitative approach to test whether an underlying pattern of relationships exists between interdependent project tasks, such that they may be rearranged into groups. In addition, a grouping efficiency index is introduced to predict how good the best possible decomposition is. The proposed approach and the grouping index are applied to simple hypothetical projects and a sample project adapted from the literature. Both the approach and the grouping index are proved to be powerful yet very easy to use.

Investigation of Inducing Vibration to Reduce Friction of Coiled Tubing in Deep Drilling Operations

This work examines the buckling behavior of constrained horizontal tubular in a cylinder subjected to axial compression force. Such configurations are of interest to coiled tubing (CT) and conventional hydrocarbon drilling. When compression force is applied beyond a critical value the coiled tubing (CT) will buckle forming sinusoidal wave and with increasing the load the CT ultimately goes into a helical configuration. The friction is introduced due to the contact between the CT and the borehole wall. Increasing the CT friction eventually leads to lock-up length beyond which the drilling cannot proceed further. Vibration is a well-known technique to reduce friction between contacting bodies in many engineering systems. An in-house experimental setup is developed to imitate the wellbore being drilled with the presence of drilling fluids and vibrating facility that has the capability to vibrate the CT axially. The setup is employed to examine the effects of amplitude and frequency of vibration on the axial force transfer and weight on bit (WOB) at normal and high temperature environments. Results show that both amplitude and frequency have significant effects in reducing the friction and they alter the buckling behavior on both normal and high temperature.Copyright