bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a Deflector for Water Aeration in Wastewater Treatment
Authors: Amano R. S. , Alkhalidi Ammar , Bryar Patrick
Published: October 2013

The aeration phase within wastewater treatment is the most power consuming step required in the treatment of waste water. After the energy crisis in 1970s increasing attention has been paid for this step to reduce the energy cost [1]. Higher standard oxygen transfer efficiency (SOTE) reduces the amount of air required to aerate wastewater which reduce the air blower power consumption. In this study SOTE was investigated for the case of adding a bubble deflector, i.e. an external geometry that directs the bubbles toward the less oxygenated water, which improves the efficiency and eliminates the effect of dead zones in a rectangular water tank.
Flow of Granular Materials Modeled as a Generalized Reiner-Rivlin Type Fluid
Authors: Wu Wei-Tao , Aubry Nadine , Massoudi Mehrdad
Published: October 2013

In this paper we use a non-linear constitutive model for flowing granular materials developed by Massoudi [1] which not only considers the effect of volume fraction but also has a viscosity which is shear rate dependent. This model is a generalization of Reiner’s model [2] derived for wet sand. Specifically we study the simple shear flow of granular materials between two horizontal plates, with the lower plate fixed and the upper plate moving at a constant speed. Numerical solutions are presented for various dimensionless parameters.
Experimentally Investigating the Thermal Effects of Cross Flow Corn Drying
Authors: Gent Stephen P. , Twedt Michael P. , Abrahamson Chad R.
Published: October 2013

This study measured the thermal effects of corn drying within a continuous cross-flow grain dryer based on a variety of operating conditions. The dryer contains a column of grain that acts as a packed bed in which the air flows through the voids between the kernels. The study analyzed the following parameters and their effects on corn drying: dryer column thickness, air flow rate per volume of corn, air drying temperature, and incoming and outgoing corn moisture. A pilot-scale cross flow corn dryer with variable column thickness, variable drying air temperature, and variable fan speed was used to experimentally dry corn. The pilot scale dryer has a drying column height of 3.35 m (132 in.), column width of 0.61 m (24 in.) and a variable thickness of 0.203 m to 0.305 m (8 to 12 in.). An array of thermocouples was arranged through the packed bed of corn to measure the thermal profile as the air propagated through the corn. The thermal profiles from the experiments were compared and evaluated among the experiments. In the United States, corn is a primary grain commodity. Improved farming practices, in conjunction with improved grain genetics, have resulted in increased grain yields and the ability to grow crops in locations not possible two decades prior. After harvesting, most grains require supplemental drying to prevent spoilage. Continuous flow grain dryers have become a common method of drying and conditioning large amounts of grain. Grain dryers are required to dry grain faster and more efficiently without sacrificing grain quality. However, higher energy costs and increased crop yields have made grain drying the second largest expense for grain producers due to their high energy consumption of propane or natural gas. The overarching goal of this study is to determine the primary factors that influence heat propagation within the packed bed of grain with the intention of incorporating these effects into numerical grain drying models.
Acoustic Energy Harvesting Using Quarter-Wavelength Straight-Tube Resonator
Authors: Li Bin , Laviage Andrew J. , You Jeong Ho , Kim Yong-Joe
Published: October 2013

Although there have been significant efforts in harvesting environmental energy, our environment is still full of wasted and unused energy. As clean, ubiquitous and sustainable energy source, acoustic energy is one of the wasted energies and is abundant in our life. Therefore, it is of great interest to investigate acoustic energy harvesting mechanism as an alternative to existing energy harvesters. In this study, in order to harvest acoustic energy, piezoelectric cantilever beams are placed inside a quarter-wavelength straight-tube resonator. When the straight-tube resonator is excited by an incident wave at its acoustic eigenfrequency, an amplified acoustic resonant wave is developed inside the tube and drives the vibration motion of the piezoelectric beams. The piezoelectric beams have been designed to have the same structural eigenfrequency as the acoustic eigenfrequency of the tube resonators to maximize the amount of the harvested energy. With a single beam placed inside the tube resonators, the harvested voltage and power become the maximum near the tube open inlet where the acoustic pressure gradient is at the maximum. As the beam is moved to the tube closed end, the voltage and power gradually decrease due to the decreased acoustic pressure gradient. Multiple piezoelectric beams have been placed along the centerline of the tube resonators in order to increase the amount of harvested energy. Due to the interruption of acoustic air particle motion caused by the beams, it is found that placing piezoelectric beams near the closed tube end is not beneficial. The output voltage of the piezoelectric beams increases linearly as the incident sound pressure increases.
Scavenging Wind Energy From Fluttering Membranes With Piezoelectric Materials
Authors: Romero Edwar , Sundararajan Visvanatha , Bonilla Nellie , Martinez Christian , Rincon Amilcar
Published: October 2013

Although wind power is a highly researched area for large scale energy production, there are also opportunities for small scale applications. The present investigation proposes a fluttering membrane with flexible piezoelectric material for wind energy generation. The working principle of this approach is based on aeroelastic flutter using a MFC piezoelectric material for energy harvesting. It has been observed that the addition of flaps at the trailing edge has the advantage to decrease the critical speed at which fluttering occurs. This allows energy generation at lower wind speeds. The addition of the flaps decreased the fluttering speed from 14.8mph to 7mph. An average voltage output as high as 232mV was obtained, while a power output of 65.5μW was found at 17.5mph.
Effect of Radiation Models on Coal Gasification Simulation
Authors: Lu Xijia , Wang Ting
Published: October 2013

Adequate modeling of radiation heat transfer is important in CFD simulation of coal gasification process. In an entrained-flow gasifer, the non-participating effect of coal particles, soot, ashes, and reactive gases could significantly affect the temperature distribution in the gasifier and hence affects the local reaction rate and life expectancy of wall materials. For slagging type gasifiers, radiation further affects the forming process of corrosive slag on the wall which can expedite degradation of the refractory lining in the gasifier. For these reasons, this paper focuses on investigating applications of five different radiation models to coal gasification process, including Discrete Transfer Radiation Model (DTRM), P-1 Radiation Model, Rosseland Radiation Model, Surface-to-Surface (S2S) Radiation Model, and Discrete Ordinates (DO) Radiation Model. The objective is to identify the pros and cons of each model’s applicability to the gasification process and determine which radiation model is most appropriate for simulating the process in entrained-flow gasifiers.

The Eulerian-Lagrangian approach is applied to solve the Navier-Stokes equations, nine species transport equations, and seven global reactions consisting of three heterogeneous reactions and four homogeneous reactions. The coal particles are tracked with the Lagrangian method. Six cases are studied—one without the radiation model and the other five with different radiation models. The result reveals that the various radiation models yield uncomfortably large uncertainties in predicting syngas composition, syngas temperature, and wall temperature. The Rosseland model does not yield reasonable and realistic results for gasification process. The DTRM model predicts very high syngas and wall temperatures in the dry coal feed case. In the one-stage coal slurry case, DTRM result is close to the S2S result. The P1 method seems to behave stably and is robust in predicting the syngas temperature and composition; it yields the result most close to the mean, but it seems to underpredict the gasifier’s inner wall temperature.
Economically Viable Fabrication Method of Nanocomposite Materials From Linear Arrays of Metallic Nanoparticles and Nanorods on Tubular Halloysite Templates
Authors: Abdullayev E. , Joshi A. , Wei W. , Zhao Y. , Lvov Y.
Published: October 2013

In this work, we report a simple fabrication method for metal nanoparticles and nanorods on halloysite supports. Silver nanorods of 15 nm diameter were synthesized by thermal decomposition of silver acetate within halloysite lumen. Nanorods had crystalline nature with [111] axis oriented ∼ 68° from the halloysite tubule main axis. Linear arrays from gold, iron, cobalt and palladium nanoparticles on halloysite external surface were also synthesized by chemical and thermal reduction method. Samples were analyzed by high-resolution transmission electron microscopy and field-emission scanning electron microscopy. These in situ syntheses offer a simple method for large scale fabrication of metallic nanorods and core-shell ceramic nanocomposites, which can be used as antimicrobial additives in plastic composites, nanoelectronic and optical materials with biocompatibility and environmentally friendly. Antimicrobial thin films were prepared based on halloysite-silver nanocomposites and tested on E. Coli and S Aureus bacterial culture. Antibacterial performance of the nanocomposite material was superior to the other conventional antimicrobial additives (silver doped bioactive glasses and carbon nanotubes). Radiation protection coatings based on fabricated nanocomposite materials is under development.
Study of Lattice Strain Propagation in Molecular Beam Epitaxy of Nano Scale Magnesium Oxide Thin Film on 6H-SiC Substrates Using Neural Network Computer Models
Authors: Uddin Ghulam Moeen , Ziemer Katherine , Zeid Abe , Kamarthi Sagar
Published: October 2013

Magnesium oxide (MgO) is a candidate for interface layer application in multifunctional heterostructures. Molecular beam epitaxy (MBE) of MgO on 6H-SiC is studied for effective integration of functional oxides. In this research we present the neural network assisted design of experiment (DOE) analysis of the crystalline structure of MgO films grown over 6H-SiC substrates. Based on reflection high energy electron diffraction (RHEED) characterization of the MgO (111) films grown we present the DOE analyses of the strain propagation in two different orientations (110 and 112) during growth process with respect to growth time, substrate temperature, magnesium source temperature, plasma intensity and percentage oxygen on the starting surface of 6H-SiC substrates. We conducted constant substrate temperature (150°C) and constant plasma intensity (350mV) analyses to quantify the relation between lattice strains in <110> and <112> directions. The constant plasma intensity analysis reveals that the growth propagates in a tensile strain mode for well reconstructed SiC surface. However, excessive oxygen on the SiC surface causes the lattice of MgO twist due to tensile strain as seen from the <110> direction and compressive strain in <112> direction. In constant substrate temperature analysis we found that the principal tensile strain inducing variable in <110> direction is growth time and the strain continues to increase as the film grows thicker. However, in <112> direction the optimum plasma intensity is critical to maintain the optimum strain in the film structure.
Transport and Deposition of Ellipsoidal Fibers in Subject-Specific Lung Airways
Authors: Feng Yu , Kleinstreuer Clement
Published: October 2013

Fine to ultrafine materials, such as spherical particles and fibers with their diverse applications ranging from cosmetics, cleaners and composites to nanomedicine are increasingly ubiquitous in the air we breathe. For example, the unique lung deposition patterns of nanoparticles and their ease-of-migration into the blood stream may cause severe health problems, as discussed by Oberdoerster et al. (2005). In contrast, multifunctional nanoparticles as well as micron fibers are also being used as drug carriers for cancer treatment (Zhang et al., 2011). While the transport and deposition of spherical nanoparticles has been analyzed (Kleinstreuer and Zhang, 2010; among others), the fate of ellipsoidal particles in subject-specific lung airways has hardly been addressed.

In this study, the Euler-Lagrange fluid-particle modeling approach (i.e., the Discrete Phase Method solver) has been employed in Fluent 13.0 (ANSYS, Canonsburg, PA). User-supplied C-programs have been added to simulate ellipsoidal fibers transport and orientation effects. The computer simulation model has been validated for fiber transport and deposition in a circular tube (Tian et al., 2012). Additionally, transitional airflow patterns were analyzed and local deposition efficiencies compared for spherical particles and fibers in a realistic human respiratory system. The capability of ellipsoidal fibers migrating into deeper lung regions was indicated and fiber deposition “hot spots” were discussed. The numerical results expand the basic understanding of the dynamics of non-spherical particles in realistic shear flows, and can be used to investigate the fate of inhaled toxic or therapeutic materials.
Adaptive Time Integration Method for DAEs of Multibody Systems
Authors: Ding Jieyu , Pan Zhenkuan
Published: October 2013

An adaptive time integration method is developed for the index-3 differential-algebraic equations (DAEs) of multibody systems to improve the computational efficiency as well as the accuracy of the results. Based on the modified general-α method, the adaptive time integration is presented. At each discrete time interval, the time step size is changed through Richardson extrapolation with definable computation accuracy. A rotary rod slider system is used to validate the presented adaptive time integration. The accuracy and efficiency are determined by the expected order of the accuracy in Richardson extrapolation.
New Blood Pressure Measurement Method Using Waveform Features
Authors: Lan H. , Al-Jumaily A. M.
Published: October 2013

The Ausculatory and the Oscillometric are the most commonly used blood pressure measurement methods worldwide. However, the ausculatory method requires professionally trained observers and is not suitable for automatic BP measurement; while the oscillometric method is less accurate in wide age groups. A new BP measurement method is introduced here which determines the subject’s BP value by features of the waveform measured by a strain sensor on the arm skin. During the cuff based measurement process, blood pulses in the brachial artery lead to artery deformations, which transfer to the arm surface in the form of surface strain and to the cuff in the form of cuff pressure oscillation. Since the cuff volume and amount of air keeps changing during the measurement, arm surface strain changes are more related to blood pulse. A piezoelectric film strain sensor is placed on the arm surface above the brachial artery to measure the surface strain. Since the artery closure statuses are different during the BP measurement process, the unique features of the measured waveform are observed in our previous study. Using these features, the subject’s BP can be determined. The analysis of these features and their relation to the subject’s BP are illustrated in this paper.
Influence of Plaque Stiffness on Change of Blood Vessel Geometry Leading Hemodynamical Changes in PVA-H Stenosis Models
Authors: Shimizu Yasutomo , Shida Shuya , Funamoto Kenichi , Hayase Toshiyuki , Ohta Makoto
Published: October 2013

One of the main factors affecting blood flow conditions in stenotic arteries is plaque geometry. Plaques can be deformed by the internal pressure, and hence plaque behavior varies depending on its stiffness. Blood flow pattern around a plaque is complicated by plaque behavior, and these complications may lead to growth of the plaque itself. Thus, we can say that geometry and mechanical properties of a plaque, and blood flow will affect each other.

To understand the relationship between plaque stiffness and flow pattern, flow measurement using elastic models, which mimic the mechanical properties of blood vessels, is required. Flow patterns with steady flows and a range of hydrostatic pressures were observed by particle image velocimetry. The results show that the model is deformed by hydrostatic pressures. Furthermore, flow patterns are also changed as the results of model deformation, especially at reattachment points. Simultaneously, we performed a numerical simulation for finding a critical parameter of the flow patterns. These results show that the reattachment length increases in the model with high stenosis severity and in a vertically oriented parent artery. In conclusion, a parent artery and plaque can deform because of internal pressure, and these deformation will affect blood flow patterns.
Modeling Material Removal in Lapping of Brittle Materials
Authors: Zhou Songsheng , Fang Alex
Published: October 2013

Lapping of polycrystalline diamond compact (PDC) is a costly and time-consuming process that demands fundamental studies to improve its efficiency and quality. A series of experiments are conducted in this study to gain insights into the effects of the most influential factors on material removal rate (MRR). The well-known Preston’s equation is found to be insufficient for a satisfactory prediction of MRR associated with PDC lapping, and a new model is developed. The current approach treats MRR as the product of removal intensity and removal density, which are formulated as simple functions of pressure, velocity and grain concentration. The newly derived model is in good accordance with the analyzed experimental results. The decrease in MRR at higher pressure and the connections between applied pressure, grain concentration and MRR can all be well explained by the proposed model.
Running the World on Renewables: Alternatives for Transmission and Low-Cost Firming Storage of Stranded Renewables as Hydrogen and Ammonia Fuels via Underground Pipelines
Authors: Leighty William C. , Holbrook John H.
Published: October 2013

We must soon “run the world on renewables” but cannot, and should not try to, accomplish this entirely with electricity transmission. We need to supply all energy, not just electricity, from diverse renewable energy (RE) resources, both distributed and centralized, where the world’s richest RE resources — of large geographic extent and high intensity — are stranded: far from end-users with inadequate or nonexistent gathering and transmission systems to deliver the energy. Electricity energy storage cannot affordably firm large, intermittent renewables at annual scale, while carbon-free gaseous hydrogen (GH2) and liquid anhydrous ammonia (NH3) fuels can: GH2 in large solution-mined salt caverns, NH3 in surface tanks, both pressurized and refrigerated.

“Smart Grid” is emerging as primarily a DSM (demand side management) strategy to encourage energy conservation. Making the electricity grid “smarter” does not:

1. Increase physical transmission capacity;

2. Provide affordable annual-scale firming storage for RE;

3. Solve grid integration problem for large, time-varying RE;

4. Alleviate NIMBY objections to new transmission siting;

5. Reduce the high O&M costs of overhead electric lines. The “smarter” grid may be more vulnerable to cyberattack. Adding storage, control, and quality adjunct devices to the electricity grid, to accommodate very high renewables content, may be technically and economically inferior to GH2 and NH3 RE systems. Thus, we need to look beyond “smart grid”, expanding our concept of “transmission”, to synergistically and simultaneously solve the transmission, firming storage, and RE integration “balancing” problems now severely constraining our progress toward “running the world on renewables”.
Notch Effects on the Tensile Property of Kenaf/Polypropylene Nonwoven Composites
Authors: Hao Ayou , Yuan Lin , Zhao Haifeng , Jiang Wei , Chen Jonathan Y.
Published: October 2013

The use of natural fibers in polymer composites is growing rapidly, especially in the automotive industry, due to the environmental concern. In this research, the open-hole effects on the tensile property of kenaf/polypropylene nonwoven composites (KPNCs) in production of automotive interior parts have been investigated. KPNCs were fabricated using kenaf fiber as reinforcement and polypropylene (PP) fiber as bonding fiber. All KPNCs were produced by carding and needle-punching techniques and thermally bonded by a panel press with 6-mm thickness gauges. Unlike the traditional fiber reinforced composites, KPNCs are produced by nonwoven technique with a 50% fiber weight ratio. Mechanical properties of the KPNCs in terms of uniaxial tensile and open-hole tensile (OHT) were measured instrumentally. By calculating the stress concentration factor Kt for brittle materials, the net section stress factor Kn for ductile materials, and the strength reduction factor Kr, we found that KPNC was relatively ductile and insensitive to the notch.
On the Nonlinear Dynamics of a Vibro-Impacting Cantilever With End Mass
Authors: Gandhi Prasanna , Badkas Ajinkya
Published: October 2013

A theoretical and experimental dynamic analysis of a vibro-impacting cantilever with end mass is presented in this paper. The cantilever is excited by transverse harmonic displacement given at its fixed end with the help of a shaker. Nonlinearity in dynamics due to impact of cantilever on a motion limiting stop only on one side is considered.

Experiments revealed quite interesting nonlinear hysteresis, jump, and drop phenomena in this case. Phenomena are experimentally characterized by varying the position and the gap between the stop and cantilever on a custom-built setup. Vibrating cantilever is modeled using assumed modes method while spring damper model for impacting stop is considered. Simulation and experimental results show close match for the same parameters under various cases of stop position and gap. Results are presented in terms of frequency response curves for range of parameters in non-dimensional form to enable their use in similar other cases.
On the Dynamics of an Inverted Flexible Pendulum With Tip Mass on a Cart
Authors: Gandhi Prasanna , Patil Ojas
Published: October 2013

Flexible link systems are increasingly becoming popular for their superior performance in micro/nano positioning and several other advantages including less weight, compact design, lower power requirements and so on as compared to other precision micro-positioning systems. The dynamics and control of such systems is challenging, especially for cases where the system is in the vertical plane. A representative case, inverted flexible pendulum on cart system, is considered in this paper. A dynamic model for flexible pendulum with tip mass has been developed using the Euler Lagrange energy method with constraints for large deflection bending. The assumed modes method approach is used to represent significant contribution to dynamics by finite number of modes. For a lower tip mass, only one stable equilibrium in the center exists; however for higher mass this equilibrium becomes unstable and two stable equilibria on side emerge. An experimental setup of the system has also been developed and it is clear by measuring strain at the base of the pendulum that the nonlinear dynamics is captured well in the proposed model.
Hydrodynamic Modeling of Circulating Fluidised Bed Boilers: An Overview
Authors: Vasan A. Mercy , Gopalakrishnan V.
Published: October 2013

The Circulating Fluidized Bed (CFB) boilers have emerged as flexible, environment-friendly equipment in recent years. Though less than 20 years old, the technology has already proved its maturity and has started replacing the Pulverized Fuel (PF) combustion in specific areas. Retrofitting and scaling-up of CFB boilers require, among other things, a clear understanding of the complex flow patterns observed in various zones of the boiler and formulating them into suitable computational models. This paper attempts to get an overview of the different modeling approaches found in literature in this regard, so that an appropriate model could be arrived at for designing large commercial-scale boilers.
Regional Strategy for the Implementation of Natural Gas as a Transportation Fuel
Authors: Barnett Nicholas , Murray Annamarie , Ouellette Nicholas , Snyder Michael
Published: October 2013

Natural gas as a transportation fuel is a practical and viable replacement for petroleum based fuels. To implement natural gas fuel technologies, strategic plans must be put in place by city, state, and national agencies to not only fund the technology with monetary investments but also fund the social change to encourage long term technology growth. With the discovery and exploration of the Marcellus Shale the potential for natural gas infiltration as a fuel into the transportation market has grown exponentially. The region of interest for this specific plan focuses on a 150 mile radius around the Pittsburgh metropolis as the initial test bed region of interest. This region lies upon the Marcellus Shale and therefore there is a positive push towards the use of natural gas fueled by local interest. This region has the intellectual knowhow from universities and government agencies alike to develop technologies from theoretical design to product deployment. To ensure an effective and successful strategy the methodology of this investigation was one which looked to the past, present and the future. Past strategies were studied to determine what key features lead to success, the present was explored to define what laws and regulations are in place which affects the new technologies, and the future benefits of a successful implementation were hypothesized based on economic theory. The proposed strategy is a closed loop operation; meaning one industrious customer is temporarily both the supply and the demand chain of the technology. Public and private investments are vital to a successful implementation in the region by steering social awareness and subsidizing the market.
A Study on the Fluid Flow for Effective Polishing Process in CMP Equipment
Authors: Joo Kang-Woo , Lee Suyeon , Hwang Jiyoung , Kim Kwang-Sun
Published: October 2013

The CMP (Chemical Mechanical Polishing) process is an essential process in the semiconductor manufacturing for MLM (Multilevel metal) with high-integration of devices. The targets of CMP process are such as: obtaining the uniform polishing rate on the wafer surface and high-grade flatness in each chip and removing the foreign substances with uniform cleaning. However, as the wiring density increases and the wafer size becomes larger for MLM structuring, some problems have been encountered such as: size of the CMP equipment, non-uniformity of the slurry distribution. The CMP in this research supplies the slurry from 12 nozzles for polishing process and it is important to decide the locations and the flow rates of the nozzles. In this research, we verified that the polishing rate on the wafer is related with the uniformity of slurry distribution. The locations of the slurry nozzles are investigated to distribute the slurry uniformly on the polishing pad using numerical analysis. The results of the research were applied to manufacture a revised CMP equipment.
High Cycle Fatigue Properties of Modified 9Cr-1Mo Steel at Elevated Temperatures
Authors: Matsumori Yoshiaki , Nemoto Jumpei , Ichikawa Yuji , Nonaka Isamu , Miura Hideo
Published: October 2013

Since high-cycle fatigue loads is applied to the pipes in various energy and chemical plants due to the vibration and frequent temperature change of fluid in the pipes, the high-cycle fatigue behavior of the alloys used for pipes should be understood quantitatively in the structural reliability design of the pipes. The purpose of this study, therefore, is to clarify the high-cycle fatigue strength and fracture mechanism of the modified 9Cr-1Mo steel at temperatures higher than 400°C. This material is one of the effective candidates for the pipes in fast breeder demonstration reactor systems. A rotating bending fatigue test was applied to samples at 50 Hz in air. The stress waveform was sinusoidal and the stress ratio was fixed at −1. The fatigue limit was observed at room temperature and it was about 420 MPa. This value was lower than the 0.2% proof stress of this alloy by about 60 MPa. This decrease can be attributed to the cyclic softening of this material. The limited cycles at knee point was about 8×105 cycles. All fracture was initiated from a single surface crack and no inclusion-induced fracture was observed in the fracture surface by SEM. Thus, the high-cycle fatigue design based on the fatigue limit may be applicable to the modified 9Cr-1Mo steel at room temperature. The fatigue limit of about 350 MPa was also observed at 400°C, and it appeared at about 107 cycles, while it appeared at around 106 cycles at room temperature. Thus, it was confirmed that the fatigue strength of this alloy decrease with temperature. However, the fatigue limit didn’t appear at 550°C up to 108 cycles. The fatigue limit may disappear in this alloy at 550°C. It is very important, therefore, to evaluate the ultra-high cycle fatigue strength of this alloy at temperatures higher than 400°C.
Mitigate Friction of Coiled Tubing by Optimization and Axial Vibrations to Facilitate Extended Reach Drilling Operations
Authors: Haneef M. Danish , Abdo Jamil
Published: October 2013

A latest development in the drilling industry is the use of coiled tubing for drilling operations (CTD) that has emerged as a viable technique to ensure cost effective and trouble free drilling operations as compared to conventional jointed pipe drilling. The major challenge in CTD is the buckling that initiates as a consequence of it being a long slender tube and friction between the borehole and the tubing is known to be the main cause. This friction causes the CT to buckle sinusoidally and with increasing axial load ultimately to a helical configuration. Sufficient wall contact forces (WCF) are developed at the well bore and tubing interface thus eventually leading to a zero force transfer downhole. Thus a lockup situation is reached, beyond which the drilling cannot proceed further. Vibration is understood to be a well known technique to reduce friction between contacting forces in many engineering systems. This work presents a detailed analysis of factors that have significant influence on wall contact force, friction, lockup depth and hence buckling. A numerical simulation based technique is used to mitigate friction to reduce buckling, by applying axial vibrations. Various frequencies of axial vibrations were applied and their effect on friction and WCF is studied. A significant improvement in lockup depth was recorded while exciting the tube axially.
Investigations on Transient Natural Convection in Boron Nitride-Mineral Oil Nanofluid Systems
Authors: Thomas Shijo , Sobhan C. B. , Taha-Tijerina Jaime , Narayanan T. N. , Ajayan P. M.
Published: October 2013

Nanofluids are suspensions or colloids produced by dispersing nanoparticles in base fluids like water, oil or organic fluids, so as to improve their thermo-physical properties. Investigations reported in recent times have shown that the addition of nanoparticles significantly influence the thermophysical properties, such as the thermal conductivity, viscosity, specific heat and density of base fluids. The convective heat transfer coefficient also has shown anomalous variations, compared to those encountered in the base fluids. By careful selection of the parameters such as the concentration and the particle size, it has been possible to produce nanofluids with various properties engineered depending on the requirement. A mineral oil–boron nitride nanofluid system, where an increased thermal conductivity and a reduced electrical conductivity has been observed, is investigated in the present work to evaluate its heat transfer performance under natural convection. The modified mineral oil is produced by chemically dispersing boron nitride nanoparticles utilizing a one step method to obtain a stable suspension. The mineral oil based nanofluid is investigated under transient free convection heat transfer, by observing the temperature-time response of a lumped parameter system. The experimental study is used to estimate the time-dependent convective heat transfer coefficient. Comparisons are made with the base fluid, so that the enhancement in the heat transfer coefficient under natural convection situation can be estimated.
Efficiency Improvement of Natural Gas Combined Cycle Power Plant With CO2 Capturing and Sequestration
Authors: Al-Abdulkarem Abdullah , Hwang Yunho , Radermacher Reinhard
Published: October 2013

Although natural gas is considered as a clean fuel compared to coal, natural gas combined cycles (NGCC) emit high amounts of CO2 at the plant site. To mitigate global warming caused by the increase in atmospheric CO2, CO2 capture and sequestration (CCS) using amine absorption is proposed. However, implementing this CCS system increases the energy consumption by about 15–20%. Innovative processes integration and waste heat utilization can be used to improve the energy efficiency. Four waste heat sources and five potential uses were uncovered and compared using a parameter defined as the ratio of power gain to waste heat. A new integrated CCS configuration is proposed, which integrates the NGCC with the CO2 removal and CO2 compression cycles. HYSYS simulation software was used to simulate the CO2 removal cycle using monoethanolamine (MEA) solution, NGCC, CO2 compression cycle, CO2 liquefaction cycles and Organic Rankine Cycle (ORC). The developed models were validated against experimental data from the literature with good agreements. Two NGCC with steam extraction configurations were optimized using Matlab GA tool coupled with HYSYS simulation software. Efficiency improvement in one of the proposed CCS configurations that uses the available waste heat in absorption chillers to cool the inlet-air to the gas turbine and to run an ORC, and uses the developed CO2 liquefaction and pumping instead of multistage compression is 6.04 percent point, which represents 25.91 MW more power than the conventional CCS configuration.
Nonlinear Control of Dynamic Systems Using Single Multiplicative Neuron Models
Authors: Turner Jonathan G. , Samanta Biswanath
Published: October 2013

The paper presents an approach to nonlinear control of dynamic systems using artificial neural networks (ANN). A novel form of ANN, namely, single multiplicative neuron (SMN) model is proposed in place of more traditional multi-layer perceptron (MLP). SMN derives its inspiration from the single neuron computation model in neuroscience. SMN model is trained off-line, to estimate the network weights and biases, using a population based stochastic optimization technique, namely, particle swarm optimization (PSO). Both off-line training and on-line learning of SMN have been considered. The development of the control algorithm is illustrated through the hardware-in-the-loop (HIL) implementation of DC motor speed control in LabVIEW environment. The controller based on SMN performs better than MLP. The simple structure and faster computation of SMN have the potential to make it a preferred candidate for implementation of real-life complex control systems.
Toward a Method for Improving Product Architecture Solutions by Integrating Designs for Assembly, Disassembly and Maintenance
Authors: Dagman Andreas , Söderberg Rikard
Published: October 2013

New customer demands and increased legislation drive business-oriented companies into new business models focusing on the entire life cycle of the product. This forces the manufacturing companies into service-oriented solutions as a compliment to the original business areas. Takata [1] postulates that “the goal is no longer to produce products in an efficient way, but rather to provide the functions needed by society while minimizing material and energy consumption”. This new situation affects the product requirements as well as product development process (PD). When focusing on the entire product life cycle, product aspects such as maintenance and repair will receive more attention since the companies will be responsible for them. In the product development process of today, especially in the automotive industry, maintenance and repair aspects (repair and maintenance methods and manuals, for example) are currently taken care of when the product is more or less fully developed. Maintenance and repair requirements are difficult to quantify in terms of core product properties (for vehicles, cost, CO2 emissions, weight, and so on). This leads to difficulties in equally considering maintenance and repair requirements while balancing vast amounts of product requirements. This paper focuses on a comparison and discussion of existing design guidelines affecting the structure and organization of parts in an assembled consumer product, such as Design for Assembly (DFA), Design for Maintenance (DFMa), Design for Service (DFS) and Design for Disassembly (DFD) methods. A tool for evaluation and analyzing product architecture as well as assemblability and maintainability is proposed.
Characterization of Cup Anemometer Dynamics
Authors: Chen Yng-Ru , Hölling Michael , Alexander J. Iwan D.
Published: October 2013

Cup anemometers are most commonly used for measuring wind speeds in the atmospheric boundary layer, among others for site assessment. The simple design of a cup anemometer consists of three cups mounted on a vertical shaft. Due to the difference in the drag coefficient of the open and the closed side of the cups the system is rotating, where the rotational frequency is proportional to the incoming wind speed. One downside of cup anemometers is their asymmetric dynamic response to accelerating and decelerating wind speeds under turbulent wind conditions. This asymmetry results in a systematic overestimation under turbulent wind conditions, the so-called over-speeding [3][4][5]. The goal of the presented experiments is to characterize the dynamical response of cup anemometers for decreasing wind velocities in particular. Additionally, the effect of different torques and an unbalanced system on the anemometer’s dynamics is investigated by adding rare earth magnets as weights to the cups. These characteristics are basis for the post processing of measured data under turbulent wind conditions. Regions of the measured time series that are dominated by the specific dynamics of the cup anemometer are therefore affected by over-speeding and should be excluded from further analysis. Systematic changes in the anemometer’s dynamics on the other hand, are indicators for damages e.g. wear of bearings or contamination of the cups [6].
Optimized Radial Basis Function Metamodel for Expensive Engineering Design Optimization
Authors: Wang Lv , Long Teng , Peng Lei , Liu Li
Published: October 2013

At the aim of alleviating the computational burden of complicated engineering optimization problems, metamodels have been widely employed to approximate the expensive blackbox functions. Among the popular metamodeling methods RBF metamodel well balances the global approximation accuracy, computational cost and implementation difficulty. However, the approximation accuracy of RBF metamodel is heavily influenced by the width factors of kernel functions, which are hard to determine and actually depend on the numerical behavior of expensive functions and distribution of samples. The main contribution of this paper is to propose an optimized RBF (ORBF) metamodel for the purpose of improving the global approximation capability with an affordable extra computational cost. Several numerical problems are used to compare the global approximation performance of the proposed ORBF metamodeling methods to determine the promising optimization approach. And the proposed ORBF is also adopted in adaptive metamodel-based optimization method. Two numerical benchmark examples and an I-beam optimization design are used to validate the adaptive metamodel-based optimization method using ORBF metamodel. It is demonstrated that ORBF metamodeling is beneficial to improving the optimization efficiency and global convergence capability for expensive engineering optimization problems.
Design and Evaluation of an In-Pipe Leak Detection Sensing Technique Based on Force Transduction
Authors: Chatzigeorgiou Dimitris M. , Ben-Mansour Rached , Khalifa Atia E. , Youcef-Toumi Kamal
Published: October 2013

Leakage is the major factor for unaccounted fluid losses in almost every pipe network. In most cases the deleterious effects associated with the occurrence of leaks may present serious economical and health problems and therefore, leaks must be quickly detected, located and repaired. The problem of leakage becomes even more serious when it is concerned with the vital supply of fresh water to the community. Leaking water pipelines can develop large health threats to people mostly because of the infiltration of contaminants into the water network. Such possibilities of environmental health disasters have spurred research into the development of methods for pipeline leakage detection.

Most state of the art leak detection techniques have limited applicability, while some of them are not reliable enough and sometimes depend on user experience. Our goal in this work is to design and develop a reliable leak detection sensing system. The proposed technology utilizes the highly localized pressure gradient in the vicinity of a small opening due to leakage in a pressurized pipeline. In this paper we study this local phenomenon in detail and try to understand it with the help of numerical simulations in leaking pipelines (CFD studies). Finally a new system for leak detection is presented.

The proposed system is designed in order to reduce the number of sensing elements required for detection. The main concept and detailed design are laid out. A prototype is fabricated and presented as a proof of concept. The prototype is tested in a simple experimental setup with artificial leakages for experimental evaluation. The sensing technique discussed in this work can be deployed in water, oil and gas pipelines without significant changes in the design, since the concepts remain the same in all cases.
Validation of 2D CFD for Two-Phase Transient Flow in a Channel and Comparison With 1D Model
Authors: Kalogerakos Stamatis , Gourma Mustapha , Thompson Chris
Published: October 2013

Severe limitations of the use of three-dimensional computational fluid dynamics codes (CFD) arise when trying to simulate multiphase flow in long pipes due to time constraints. 1D codes for two-phase flow, based on two-fluid models, are fast but are known to be accurate only when the velocities are within the Kelvin-Helmholtz inviscid limit [1]. An alternative is to carry out a two-dimensional CFD simulation of a channel based on the Volume of Fluid (VOF) model. 2D CFD has a wider applicability range compared to 1D, it does not have the issue of ill-posedness and it also has better turbulence models built in. Again compared to 1D the 2D VOF model has a better interface description and wall treatment. In this paper a novel method is introduced that allows swift simulations of pipeline two-phase flow in the stratified and slug flow regime, by approximating the pipe as a channel and with a methodology that solves the problem of the interfacial velocity differences, inherent in the volume of fluid model. An initial validation using the wave growth problem has already been carried out [2]. Here a set consisting of 92 experimental cases in the slug flow regime has been simulated with 2D CFD, and the simulation results showed a good agreement with experimental results. Discussions in the paper include also the question of the range of applicability for 2D CFD, and the advantages and disadvantages compared to 3D CFD and also to 1D code based on the two-fluid model. Shear stresses are then extracted from the 2D CFD simulations and used to recalibrate the friction factors [3] used in the 1D code.
Rotorcraft Pilot Impedance From Inverse Dynamics-Based Biomechanical Model
Authors: Zanoni Andrea , Quaranta Giuseppe , Masarati Pierangelo
Published: October 2013

The involuntary interaction of the pilot with a vehicle is often an undesired consequence of the biomechanical properties of the human body and its relation with the layout of the man-machine interface. This work discusses how muscular activation patterns affect the variability of the equivalent impedance of helicopter pilots. A multibody model is used to compute the joint torques associated to a prescribed pilot task, which are then transformed into corresponding ‘optimal’ muscular activation patterns. Equivalent pilot impedance is obtained by consistently linearizing the constitutive model of the muscles about the reference activation. The effect on equivalent impedance of non-optimal activation, resulting from the addition of Torque-Less Activation Modes to the optimal activation, is evaluated and discussed.
3-D Multibody Modeling of a Flexible Surgical Instrument Inside an Endoscope
Authors: Khatait J. P. , Brouwer D. M. , Meijaard J. P. , Aarts R. G. K. M. , Herder J. L.
Published: October 2013

Modern surgical procedures involve flexible instruments for both diagnostic and therapeutic purposes. The implementation of flexible instruments in surgery necessitates high motion and force fidelity, and good controllability of the tip. However, the positional accuracy and the force transmission of these instruments are jeopardized by the friction and clearance inside the endoscope, and the compliance of the instrument.

The objective of this paper is to set up a 3-D flexible multibody model for a surgical instrument inside an endoscope to study its translational and rotational behavior. The 3-D model incorporates all the deformations—axial, torsion, and bending—due to its interaction with the surroundings. The interaction due to the contact is defined along the normal and tangential direction at the contact point. The wall stiffness and damping are defined in the normal direction. Friction is defined along the tangential direction. The calculation of the interaction force and moment is explained with an example.

Various simulations were performed to study the behavior of the instrument inside a curved rigid tube. The simulations for the insertion into a 3-D tube defined in a plane were compared for both 2-D and 3-D model. The simulation results from the 3-D model give the same results as the 2-D model. A simulation was carried out for the insertion in a 3-D tube using the 3-D model and the total interaction force on the instrument was analyzed. A 3-D multibody model was set up for the simulation offline rotation. A motion hysteresis of 5° was observed for the chosen configuration.

The 3-D multibody model is able to demonstrate the characteristic behavior of the flexible instrument under different scenarios. Both translational and rotational behavior of the instrument can be characterized for the given set of parameters. The developed model will help us to study the effect of various parameters on the motion and force transmission of the instrument.