Mechanical Engineering Commons^™

Criteria On Utility Designing Of Convex Optimization In Fdma Networks, Zheng Sun, Wenjun Xu, Zhiqiang He, Kai Niu

Zheng Sun

In this paper, we investigate the network utility maximization problem in FDMA systems. We summarize with a suite of criteria on designing utility functions so as to achieve the global optimization convex. After proposing the general form of the utility functions, we present examples of commonly used utility function forms that are consistent with the criteria proposed in this paper, which include the well-known proportional fairness function and the sigmoidal-like functions. In the second part of this paper, we use numerical results to demonstrate a case study based on the criteria mentioned above, which deals with the subcarrier scheduling problem …

Formation Characteristics Of Aerosol Particles From Pulverized Coal Pyrolysis In High-Temperature Environments, Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.

Measurement And Analysis Of Vitiation Of Secondary Air In Air Distribution Systems (Rp-1276), David P. Yuill, Grenville K. Yuill, Andrew H. Coward

David Yuill

7 - تأثير نوع پوشش محوطه اطراف ساختمان بر مصرف سالانه انرژي, Alireza Zolfaghari, Mehdi Maerefat

Dr Alireza Zolfaghari

No abstract provided.

6 - مدلسازي و تحليل پاسخ حرارتي بدن انسان در برابر تابشهاي شدت بالا, Alireza Zolfaghari, Mehdi Maerefat, Amir Omidvar

Dr Alireza Zolfaghari

No abstract provided.

Three-Dimensional Data Merging Using Holoimage, Song Zhang, Shing-Tung Yau

Song Zhang

Three-dimensional data merging is vital for full-field three-dimensional (3D) shape measurement. All 3D range data patches, acquired from either different sensors or the same sensor in different viewing angles, have to be merged into a single piece to facilitate future data analysis. A novel method for 3D data merging using Holoimage is proposed. Similar to the 3D shape measurement system using a phase-shifting method, Holoimage is a phase-shifting–based computer synthesized fringe image. The 3D information is retrieved from Holoimage using a phase-shifting method. If two patches of 3D data with overlapping areas are rendered by OpenGL, the overlapping areas are …

Proceedings From Scientific Conference On Green Energy And It, Dr. Erik Dahlquist

Dr. Erik Dahlquist

This conference is part of the annual Energitinget, a national arena for energy in Sweden, with some 2500 participants. The focus with this session is to give a forum for researchers to present scientific results, and also to discuss these with other researchers. It contains papers in the area of Energy and IT as well as Green energy generally

Liga Fabrication Of Nanocrystalline Ni-Walloy Micro Specimens From Ammonia-Citrate Bath, Haseeb Asma

Haseeb ASMA

Ammonia-citrate bath has been investigated for the deposition of nano crystalline Ni - W alloy micro components using the LIGA process. First the bath stability and deposit characteristics were studied. Fabrication of micro specimens were then carried out on silicon substrates covered with novolac as well as thick PMMA resist for LIGA. Effects of different parameters like current density, nickel ion and tungsten ion concentration in the bath, deposition time etc. on the deposit characteristics and current efficiency were studied. The deposited Ni - W samples were characterized by scanning electron microscopy, energy depressive X-ray spectroscopy, light optical microscopy and …

5 - تأثير فرش کردن کف اتاق با قالي و يا برخي پوششهاي سنتي- تزييني مشابه بر عملکرد سيستمهاي گرمايش از کف هيدرونيک, Amir Omidvar, Alireza Zolfaghari, Mehdi Maerefat

Dr Alireza Zolfaghari

No abstract provided.

4 - تأثير نوع شيشة پنجره بر مصرف انرژي و شرايط آسايش حرارتي در سيستم سرمايش تابشي سقفي, Alireza Zolfaghari, Amir Omidvar, Mehdi Maerefat

Dr Alireza Zolfaghari

No abstract provided.

Laboratory Experiments As Support To The Built Up Of Titan’S Theoretical Models And Interpretation Of Cassini-Huygens Data, M-C. Gazeau, Y Benilan, Et. Es-Sebbar, T. Ferradaz, E. Hébrard, A. Jolly, F. Raulin, C. Romanzin, J-C. Guillemin, C. Berteloite, A. Canosa, S. D. Le Picard, Ian R. Sims

Dr. Et-touhami Es-sebbar

No abstract provided.

3 - مدلسازي و تحليل پاسخ حرارتي بدن تحت تأثير صرف غذاي سرد يا گرم, Alireza Zolfaghari, Amir Omidvar, Mehdi Maerefat

Dr Alireza Zolfaghari

No abstract provided.

A Preliminary Assessment Of The State Of Harvest And Collection Technology For Forest Residues, Erin G. Wilkerson, D. Brad Blackwelder, Robert D. Perlack, David J. Muth, J. Richard Hess

David J. Muth

To meet the “Twenty in Ten Initiative” goals set in the 2007 State of the Union address, forest resources will be needed as feedstocks for lignocellulosic ethanol production. It has been estimated that 368 million dry tons can be produced annually in the U.S. from logging residues and fuel treatment thinnings. Currently, very little of this woody biomass is used for energy production due to the costs and difficulty in collecting and transporting this material. However, minimizing biomass costs (including harvest, handling, transport, storage, and processing costs) delivered to the refinery is necessary to develop a sustainable cellulosic ethanol industry. …

Three-Dimensional Shape Measurement Using A Structured Light System With Dual Cameras, Song Zhang, Shing-Tung Yau

Song Zhang

A structured light system for three-dimensional shape measurement with single camera has the shortcoming of camera occlusion. To alleviate this problem, this paper introduces a structured light system with dual cameras for three-dimensional shape measurement. We discuss (1) system description, (2) system calibration, (3) three-dimensional data registration using the iterative closest-point (ICP) algorithm, and (4) three-dimensional data merging using holoimage. The principle of the system is introduced, and experiments are presented to verify its performance.

Modeling And Control Of Formations Of Nonholonomic Mobile Robots, Jaydev P. Desai, James P. Ostrowski, R. Vijay Kumar

R. Vijay Kumar

This paper addresses the control of a team of nonholonomic mobile robots navigating in a terrain with obstacles while maintaining a desired formation and changing formations when required, using graph theory.We model the team as a triple, (g, r, H), consisting of a group element g that describes the gross position of the lead robot, a set of shape variables r that describe the relative positions of robots, and a control graph H that describes the behaviors of the robots in the formation. Our framework enables the representation and enumeration of possible control graphs and the coordination of transitions between …

Control Of Mechanical Systems With Rolling Constraints: Application To Dynamic Control Of Mobile Robots, Nilanjan Sarkar, Xiaoping Yun, R. Vijay Kumar

R. Vijay Kumar

There are many examples of mechanical systems which require rolling contacts between two or more rigid bodies. Rolling contacts engender nonholonomic constraints in an otherwise holonomic system. In this paper, we develop a unified approach to the control of mechanical systems subject to both holonomic and nonholonomic constraints. We first present a state space realization of a constrained system and show that it is not input-state linearizable. We then discuss the input-output linearization and zero dynamics of the system. This approach is applied to the dynamic control of mobile robots. Two types of control algorithms for mobile robots are investigated: …

Friction And Wear Characteristics Of Electrodeposited Nanocrystalline Nickel-Tungsten Alloy Films

A.S. Md Abdul Haseeb

Electrodeposited nanocrystalline nickel-tungsten alloys are being investigated as an attractive alternative to electrodeposited nickel for applications involving fabrication of micro electro mechanical systems (MEMS). Ni-W alloys are also being considered as an environmentally friendly alternative to hard chrome plating in some cases. In applications involving sliding contacts such as in micro-gears in MEMS, mould inserts, etc., tribological properties of Ni-W alloys would be of relevance. In this work, the sliding friction and wear characteristics of Ni-W alloys with different tungsten contents were investigated and compared with that of nickel film deposited from sulphamate bath commonly used in microfabrication. For wear …

Liga Fabrication Of Nanocrystalline Ni-W Alloy Micro Specimens From Ammonia-Citrate Bath

A.S. Md Abdul Haseeb

Ammonia-citrate bath has been investigated for the deposition of nano crystalline Ni-W alloy micro components using the LIGA process. First the bath stability and deposit characteristics were studied. Fabrication of micro specimens were then carried out on silicon substrates covered with novolac as well as thick PMMA resist for LIGA. Effects of different parameters like current density, nickel ion and tungsten ion concentration in the bath, deposition time etc. on the deposit characteristics and current efficiency were studied. The deposited Ni-W samples were characterized by scanning electron microscopy, energy depressive X-ray spectroscopy, light optical microscopy and X-ray diffraction. Results show …

Liga Fabrication Of Nanocrystalline Ni-W Alloy Micro Specimens From Ammonia-Citrate Bath

A.S. Md Abdul Haseeb

Ammonia-citrate bath has been investigated for the deposition of nano crystalline Ni-W alloy micro components using the LIGA process. First the bath stability and deposit characteristics were studied. Fabrication of micro specimens were then carried out on silicon substrates covered with novolac as well as thick PMMA resist for LIGA. Effects of different parameters like current density, nickel ion and tungsten ion concentration in the bath, deposition time etc. on the deposit characteristics and current efficiency were studied. The deposited Ni-W samples were characterized by scanning electron microscopy, energy depressive X-ray spectroscopy, light optical microscopy and X-ray diffraction. Results show …

Thermal Stability Of Electrodeposited Liga Ni-W Alloys For High Temperature Mems Applications

A.S. Md Abdul Haseeb

For thermally stable LIGA materials for high temperature MEMS applications LIGA Ni-W layers and micro testing samples with different compositions (15 and 5 at% W) were electrodeposited. In order to investigate the thermal stability the Ni-W layers were annealed at different temperatures (300-700°C) and for different durations (1, 4, 16 h). Their microstructure and micro-hardness were than analysed after annealing and compared with those of as-deposited states. The observed microstructures show, in comparison to pure LIGA nickel, a small grain growth and a relatively stable structure up to 700°C. The micro-hardness values of the LIGA Ni-W layers are higher than …

Friction And Wear Characteristics Of Electrodeposited Nanocrystalline Nickel-Tungsten Alloy Films, Haseeb Asma

Haseeb ASMA

Electrodeposited nanocrystalline nickel-tungsten alloys are being investigated as an attractive alternative to electrodeposited nickel for applications involving fabrication of micro electro mechanical systems (MEMS). Ni-W alloys are also being considered as an environmentally friendly alternative to hard chrome plating in some cases. In applications involving sliding contacts such as in micro-gears in MEMS, mould inserts, etc., tribological properties of Ni-W alloys would be of relevance. In this work, the sliding friction and wear characteristics of Ni-W alloys with different tungsten contents were investigated and compared with that of nickel film deposited from sulphamate bath commonly used in microfabrication. For wear …

Modeling Of Dispersed Phase By Lagrangian Approach In Fluent - 2d Exercise, Kari Myöhänen

Kari Myöhänen

This shows an example calculation applying DPM model in Fluent. This is related to the other DPM presentation and was prepared for the course 'Theory and simulation of dispersed-phase multiphase flows" by Dr. Payman Jalali, Lappeenranta University of Technology.

Modeling Of Dispersed Phase By Lagrangian Approach In Fluent, Kari Myöhänen

Kari Myöhänen

This is a seminar work prepared for a course 'Theory and simulation of dispersed-phase multiphase flows' by Dr. Payman Jalali, Lappeenranta University of Technology

Use Of Modeling And Simulation In Pulp And, Dr. Erik Dahlquist

Dr. Erik Dahlquist

The book is a handbook for operators and process engineers in primarily pulp and paper industry, but also other process industries about how to utilise simulation as a tool for enhanced process operations. The book has been written as part of a EU COST action on Process Simulation, with 14 countries and 50 researchers and process industry representatives involved.

The Nonlinear Dynamics Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, H. Dankowicz, M.R. Paul

Nastaran Hashemi

We study the nonlinear dynamics of a tapping mode atomic force microscope with tip-surface interactions that include attractive, repulsive, and capillary force contributions using numerical techniques tailored for hybrid or discontinuous dynamical systems that include forward-time simulation with event handling and numerical pseudo-arclength continuation. We find four branches of periodic solutions that are separated by windows of complex and irregular dynamics. The branches of periodic solutions end where the cantilever comes into grazing contact with event surfaces in state space, corresponding to the onset of capillary interactions and the onset of repulsive forces associated with contact. These windows of irregular …

The Dissipated Power In Atomic Force Microscopy Due To Interactions With A Capillary Fluid Layer, Nicole N. Hashemi, M.R. Paul, H. Dankowicz, W. Jhe

Nastaran Hashemi

We study the power dissipated by the tip of an oscillating micron-scale cantilever as it interacts with a sample using a nonlinear model of the tip-surface force interactions that includes attractive, adhesive, repulsive, and capillary contributions. The force interactions of the model are entirely conservative and the dissipated power is due to the hysteretic nature of the interaction with the capillary fluid layer. Using numerical techniques tailored for nonlinear and discontinuous dynamical systems we compute the exact dissipated power over a range of experimentally relevant conditions. This is accomplished by computing precisely the fraction of oscillations that break the fluid …

Melt-Dispersion Mechanism For Fast Reaction Of Aluminum Particles: Extension For Micron Scale Particles And Fluorination, Valery I. Levitas, Michelle L. Pantoya, Kyle W. Watson

Valery I. Levitas

The theoretically predicted relationship for the relative flame rate versus relative particle size based on the melt dispersion mechanism (MDM), which was previously confirmed for oxidation of 40–120nm diameter aluminum particles, is found to be in agreement with experiments for 1–3μm diameter Al particles and fluorination. The main physical parameters for MDM (pressure in molten particle, cavitation threshold, and nanoclusters’ velocity) have been estimated for micron scale particles. The results suggest parameters that could be controlled during particle synthesis that would enable micron scale Al particles to react and achieve the performance of nanoscale Al particles.

Melt Dispersion Versus Diffusive Oxidation Mechanism For Aluminum Nanoparticles: Critical Experiments And Controlling Parameters, Valery I. Levitas, Michelle L. Pantoya, Birce Dikici

Valery I. Levitas

Critical experiments were performed on Al and MoO3 thermites. The diameter and alumina shell thickness of the Alnanoparticles were varied, and flame propagation velocities were measured. The results strongly support the melt-dispersion mechanism and contradict the diffusionoxidation mechanism. The parameters that control the oxidation rate and flame velocity are justified and directions for the synthesis of Alnanoparticles (which are opposite to the current directions based on diffusionoxidation) are suggested. An equation for the flame velocity versus Alnanoparticle geometrical parameters, thermomechanical properties, and synthesis parameters is formulated.

Finite Element Modeling Of Dynamics Of Martensitic Phase Transitions, Alexander V. Idesman, Joon Yeoun Cho, Valery I. Levitas

Valery I. Levitas

A finite element approach is suggested for the modeling of the dynamics of multivariant martensitic phase transitions (PTs) in elasticmaterials at the nanoscale in the three dimensional (3D) case. The model consists of a coupled system of the Ginzburg–Landau equations for transformation strain-related order parameters and dynamic elasticity equations. Thermodynamic potential [V. Levitas and D. Preston, Phys. Rev. B66, 134206 (2002)] that captures the main features of macroscopic stress-strain curves is used. The evolution of multivariant microstructure in a 3D specimen for cubic to tetragonal PT in a NiAl alloy is modeled with dynamic and static formulations. The numerical results …

Morphologies And Kinetics Of A Dewetting Ultrathin Solid Film, Mikhail Khenner

Mikhail Khenner

The surface evolution model based on geometric partial differential equation is used to numerically study the kinetics of dewetting and dynamic morphologies for the localized pinhole defect in the surface of the ultrathin solid film with the strongly anisotropic surface energy. Depending on parameters such as the initial depth and width of the pinole, the strength of the attractive substrate potential and the strength of the surface energy anisotropy, the pinhole may either extend to the substrate and thus rupture the film, or evolve to the quasiequilibrium shape while the rest of the film surface undergoes phase separation into a …