Digital Commons Network^™

26 - تحليل تأثيرگذاري ميزان مقاومت حرارتي جداره و جهت جداره هاي نورگذر بر اندازه بهينه پنجره در اقليم تهران, Mona Khatami, Maria Kord-Jamshidi, Behrouz Mohamad Kari, Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.

25 - تحليل تأثيرات استفاده از عايقهاي تغيير فاز دهنده بر ميزان مصرف سالانه انرژي ساختمان در اقليم تهران, Alireza Zolfaghari, Mohamad Solhi, Mohamad Fathian, Hamed Moslehi, Mohamad Rahim-Pour, Mehran Sa'adati-Nasab

Dr Alireza Zolfaghari

No abstract provided.

Us Patent 8,338,976: Magnetically­-Levitated Wind Turbine, Sanza Kazadi

Sanza Kazadi

Application Of Structured Light Imaging For High Resolution Mapping Of Underwater Archaeological Sites, Chris Roman, Gabrielle Inglis, James Rutter

Christopher N. Roman

This paper presents results from recent work using structured light laser profile imaging to create high resolution bathymetric maps of underwater archaeological sites. Documenting the texture and structure of submerged sites is a difficult task and many applicable acoustic and photographic mapping techniques have recently emerged. This effort was completed to evaluate laser profile imaging in comparison to stereo imaging and high frequency multibeam mapping. A ROV mounted camera and inclined 532 nm sheet laser were used to create profiles of the bottom that were then merged into maps using platform navigation data. These initial results show very promising resolution …

The 2005 Chios Ancient Shipwreck Survey: New Methods For Underwater Archaeology, Brendan P. Foley, Katerina Dellaporta, Dimitris Sakellariou, Brian S. Bingham, Richard Camilli, Ryan M. Eustice, Dionysis Evagelistis, Vicki Lynn Ferrini, Kostas Katsaros, Dimitris Kourkoumelis, Aggelos Mallios, Paraskevi Micha, David A. Mindell, Christopher Roman, Hanumant Singh, David S. Switzer, Theotokis Theodoulou

Christopher N. Roman

In 2005 a Greek and American interdisciplinary team investigated two ship wrecks off the coast of Chios dating to the 4th-century B.C. and the 2nd/lst century. The project pioneered archaeological methods of precision acoustic, digital image, and chemical survey using an autonomous underwater vehicle (AUV) and in-situ sensors, increasing the speed of data acquisition while decreasing costs. The AUV recorded data revealing the physical dimensions, age, cargo, and preservation of the wrecks. The earlier wreck contained more than 350 amphoras, predominantly of Chian type, while the Hellenistic wreck contained about 40 Dressel 1C amphoras. Molecular biological analysis of two amphoras …

Modeling And Performance Evaluation Of Machining Spindle With Active Magnetic Bearings, Jerzy T. Sawicki, Eric H. Maslen, Kenneth R. Bischof

Jerzy T. Sawicki

Active magnetic bearings (AMBs) are increasingly employed in the machine tool industry to exploit their advantages over classical bearings such as high speed capability, rotation accuracy, high stiffness, and accurate displacement tracking capability. Furthermore, the possibility of on-line monitoring of the machining process (e.g., cutting force measurement, tool wear) makes AMB spindles very appealing to the High-Speed Machining (HSM) industry. Despite significant progress already reached in HSM technology, there remain numerous open challenges in modeling and control of magnetic bearings as applied to machining spindles. These include optimum control given AMB magnetic saturation levels, management of nonlinear effects, reduction of …

24 - تحليل عملکرد کانالهاي زير زميني جهت تامين هواي لازم براي تهويه فضاهاي صنعتی با در نظر گرفتن زمان لازم براي احياي سيستم, Alireza Zolfaghari, Mozhgan Nikoudel, Hosein Vatan-Pour

Dr Alireza Zolfaghari

No abstract provided.

Modelling Three-Phase Flow In Metallurgical Processes, Christoph Goniva, Gijsbert Wierink, Kari Heiskanen, Stefan Pirker, Christoph Kloss

Gijsbert Wierink

The interaction between gasses, liquids, and solids plays a critical role in many processes, such as coating, granulation and the blast furnace process. In this paper we present a comprehensive numerical model for three phase flow including droplets, particles and gas. By means of a coupled Computational Fluid Dynamics (CFD) - Discrete Element Method (DEM) approach the physical core phenomena are pictured at a detailed level. Sub-models for droplet deformation, breakup and coalescence as well as droplet-particle and wet particle-particle interaction are applied. The feasibility of this model approach is demonstrated by its application to a rotating drum coater. The …

Combustion Characteristics Of Late Injected Cng In A Spark Ignition Engine Under Lean Operating Condition, Ftwi Yohaness Hagos, A. Rahsid Abd Aziz, Shaharin A. Sulaiman

Ftwi Yohaness Hagos

Lean combustion strategy is used as a tool in the reduction of greenhouse gas emission in a natural gas fuelled engines. It also increases the thermal efficiency of the combustion. In this study, late injection and stratification effect of lean charge CNG combustion in a four stroke direct injection spark ignited engine was experimentally investigated. The fuel injection is kept at 90° Crank Angle (CA) Before Top Dead Center (BTDC) and the ignition timing at 28° CA BTDC at wide open throttle. Results from this study demonstrate that Indicated Mean Effective Pressure (IMEP), it's Coefficient Of Variation (COV), in cylinder …

خلاصه روابط و معادلات

Dr Alireza Zolfaghari

No abstract provided.

Ios Model Viewer, Benjamin M. Sloan

Benjamin M. Sloan

The OBJ model viewer for iOS was developed to enable an iPad to display and allow users to interact with a design as it was being three-dimensionally printed. Current iOS application restrict user interaction to a single still view or a slide show of still views. The iOS OBJ Loader was first attempted to be written in openGL es but a custom library ended being used called Nevenah to develop the application. In addition to interacting with the loaded model the users could also adjust the lighting to understand how the material reflected light and also load different models that …

Fluid–Structure Interaction Modeling Of Wind Turbines: Simulating The Full Machine, Ming-Chen Hsu, Yuri Bazilevs

Ming-Chen Hsu

In this paper we present our aerodynamics and fluid–structure interaction (FSI) computational techniques that enable dynamic, fully coupled, 3D FSI simulation of wind turbines at full scale, and in the presence of the nacelle and tower (i.e., simulation of the “full machine”). For the interaction of wind and flexible blades we employ a nonmatching interface discretization approach, where the aerodynamics is computed using a low-order finite-element-based ALE-VMS technique, while the rotor blades are modeled as thin composite shells discretized using NURBS-based isogeometric analysis (IGA). We find that coupling FEM and IGA in this manner gives a good combination of efficiency, …

Isogeometric Fluid–Structure Interaction Analysis With Emphasis On Non-Matching Discretizations, And With Application To Wind Turbines, Y. Bazilevs, Ming-Chen Hsu, M. A. Scott

Ming-Chen Hsu

In this paper we develop a framework for fluid–structure interaction (FSI) modeling and simulation with emphasis on isogeometric analysis (IGA) and non-matching fluid–structure interface discretizations. We take the augmented Lagrangian approach to FSI as a point of departure. Here the Lagrange multiplier field is defined on the fluid–structure interface and is responsible for coupling of the two subsystems. Thus the FSI formulation does not rely on the continuity of the underlying function spaces across the fluid–structure interface in order to produce the correct coupling conditions between the fluid and structural subdomains. However, in deriving the final FSI formulation the interface …

Storage Stability Of Biofuel, Mahendra Varman Munusamy M. Varman

Mahendra Varman Munusamy (M. Varman)

Biofuel is one of the prime candidates to take over the role played by fossil fuel as the main source of energy in the future. Numerous studies have been done on the potential of biofuel to produce similar power output generated by the current petrol and diesel which are depleting without any drawbacks. The objective of this particular study is to investigate 4 of the more established vegetable oil in the energy industry namely jatropha, palm, coconut and canola oil in terms of storage stability of biofuel at room temperature and 80ºC. The biofuels were tested in terms of density, …

Super Critical Steam Turbine, Vijaya Krushna Varma Mr

VIJAYA KRUSHNA VARMA Mr

Varma designed ultra modern and high efficiency turbines which can use gas, steam or fuels as feed to produce electricity or mechanical work for wide range of usages and applications in industries or at work sites. Varma turbine engines can be used in all types of vehicles. These turbines can also be used in aircraft, ships, battle tanks, dredgers, mining equipment, earth moving machines etc http://turbine.net.in

Structural Damage Detection Using Modal Norms, W. Gawronski, Jerzy T. Sawicki

Jerzy T. Sawicki

No abstract provided.

Comments On Response Errors Of Non-Proportionally Lightly Damped Structures, W. Gawronski, Jerzy T. Sawicki

Jerzy T. Sawicki

Letters to the editor authors reply

Diophantine Type Fractional Derivative Representation Of Structural Hysteresis, Part I: Formulation, Joe Padovan, Jerzy T. Sawicki

Jerzy T. Sawicki

Based on a diophantine representation of the operational powers, a fractional derivative modelling scheme is developed to simulate frequency dependent structural damping. The diophantine set of powers is established by employing the curvature properties of the defining empirical data set. These together with a remezed least square scheme are employed to construct a Chebyschev like optimal differintegro simulation. Based on the use of the rational form resulting from the diophantine representation, a composition rule is introduced to reduce the differintegro simulation to first order form. The associated eigenvalue/vector properties are then explored. To verify the robustness-stability accuracy of the overall …

Vibration Based Crack Detection In A Rotating Disk: Part 1—An Analytical Study, Andrew L. Gyekenyesi, Jerzy T. Sawicki, George Y. Baaklini

Jerzy T. Sawicki

This paper describes the analytical results concerning the detection of a crack in a rotating disk. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk’s geometry as well as a change in the system’s center of mass occurs. Finite element analyses were conducted concerning a notched disk in order to define the sensitivity of the method. The notch was used to simulate an actual crack and will be the method utilized for upcoming experiments. …

System Identification Methods For Dynamic Testing Of Fluid-Film Bearings, Jerzy T. Sawicki, M. L. Adams, R. J. Capaldi

Jerzy T. Sawicki

There are various system identification approaches typically used to extract the rotordynamic coefficients from simultaneously measured dynamic force and motion signals. Since the coefficient values extracted can vary significantly as a function of the system identification approach used, more attention is needed to treat this issue than is typically included in the rotor dynamics literature. This paper describes system identification and data reduction methods used for extracting rotordynamic coefficients of fluid-film journal bearings. Data is used from a test apparatus incorporating a double-spoolshaft spindle which permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular …

Transient Response Of Rotor On Rolling-Element Bearings With Clearance, David P. Fleming, Brian T. Murphy, Jerzy T. Sawicki, J. V. Poplawski

Jerzy T. Sawicki

Internal clearance in rolling element bearings is usually present to allow for radial and axial growth of the rotor-bearing system and to accommodate bearing fit-up. The presence of this clearance also introduces a “dead band” into the load-deflection behavior of the bearing. Previous studies demonstrated that the presence of dead band clearance might have a significant effect on synchronous rotor response. In this work, the authors investigate transient response of a rotor supported on rolling element bearings with internal clearance. In addition, the stiffness of the bearings varies nonlinearly with bearing deflection and with speed. Bearing properties were accurately calculated …

Balanced Dissipative Controllers For Flexible Structures, W. Gawronski, Jerzy T. Sawicki

Jerzy T. Sawicki

A balanced approach to shaping the closed-loop properties of the dissipative controllers for flexible structures is presented. In the balanced representation the properties of flexible structures are introduced, and a simple method of designing of the dissipative controllers is obtained. It relates the controller gains with the closed-loop pole locations. The examples illustrate the accuracy of the design method.

Diophantinized Fractional Representations For Nonlinear Elastomeric Media, Joe Padovan, Jerzy T. Sawicki

Jerzy T. Sawicki

This paper explores the use of diophantinized fractional fits for the nonlinear constitutive representation of elastomeric media. These are caste in terms of either the principal stretches or the strain invariants. Both polynomial and rational forms are considered. To construct the requisite complete and physically admissible basis space, the diophantinized set of fractional powers is bound by the curvature properties of the experimental data set. This set is then employed in conjunction with a remezed least square scheme to obtain an optimal fit. To verify the scheme a sample application case is presented.

Diophantine Type Fractional Derivative Representation Of Structural Hysteresis, Part Ii: Fitting, Computational Mechanics, Jerzy T. Sawicki, Joe Padovan

Jerzy T. Sawicki

Part I of this series introduced the diophantinized fractional model and the decompositional formulation. The various important properties of fractional continuum formulation and its decomposed version were developed. In Part II the dynamic properties of the diophantine representation are investigated. The model fitting scheme will be developed to handle an arbitrary frequency dependent structural hysteriesis. This is followed up with the results of benchmark studies which demonstrate the effectiveness of fitting.

Thermal Degradation Of Foamed Polymethyl Methacrylate In The Expendable Pattern Casting Process, S. Mehta, Satya S. Shivkumar

Satya Shivkumar

The thermal degradation of foamed polymethyl methacrylate (PMMA) patterns in the expendable pat-tern casting process has been studied. Various physical transitions that may occur during the degradation of PMMA have been determined using scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis, and the effects of polymer density on the degradation characteristics have been investigated. The results indicate that, when exposed to elevated temperatures, the polymer beads collapse at about 140 to 200 °. The collapsed beads melt at 260 ° and begin to volatilize. Peak volatilization temperatures are on the order of 370 °. The end temperature for volatilization …

Plane Simple Shear Of Smooth Inelastic Circular Disks - The Anisotropy Of The 2nd Moment In The Dilute And Dense Limits, J. T. Jenkins, Mark W. Richman

Mark W Richman

We consider a plane, steady, homogeneous flow of circular disks. The disks are identical, smooth, and inelastic. We adopt the assumption of molecular chaos and introduce an anisotropic Maxwellian velocity distribution function based on the full second moment of the velocity fluctuations. In the limits of dilute and dense flows, we determine approximate analytic solutions of the balance law for the second moment that result in stresses whose qualitative behaviour and magnitudes are in good agreement with numerical simulations.

Utilization Of Coupling Effects In Compensator Design For Structural Acoustic Systems, H. T. Banks, Michael A. Demetriou, R. C. Smith

Michael Demetriou

The quantification and utilization of coupling effects in a prototypical structural acoustic system are examined in this paper. In typical systems, the coupling mechanisms are manifested in two ways. The first leads to the transfer of energy from an ambient field to an adjacent structure and is often responsible-for exogenous structural excitation. The second involves the transfer of energy from the vibrating structure to an adjacent field. This is the source of structure-borne noise and is ultimately the mechanism through which structural actuators are utilized to attenuate noise. The examples presented here demonstrate that in fully coupled systems, both mechanisms …

Reengineering Engineering-Education: Paradigms And Paradoxes, Diran Apelian

Diran Apelian

No abstract provided.

Undulatory Swimming In Viscoelastic Fluids, Xiaoning Shen, Paulo E. Arratia

Xiaoning Shen

The effects of fluid elasticity on the swimming behavior of the nematode Caenorhabditis elegans are experimentally investigated by tracking the nematode’s motion and measuring the corresponding velocity fields. We find that fluid elasticity hinders self-propulsion. Compared to Newtonian solutions, fluid elasticity leads to up to 35% slower propulsion. Furthermore, self-propulsion decreases as elastic stresses grow in magnitude in the fluid. This decrease in self-propulsion in viscoelastic fluids is related to the stretching of flexible molecules near hyperbolic points in the flow.

Propulsive Force Measurements And Flow Behavior Of Undulatory Swimmers At Low Reynolds Number, Josué Sznitman, Xiaoning Shen, Raphael Sznitman, Paulo E. Arratia

Xiaoning Shen

The swimming behavior of the nematode Caenorhabditis elegans is investigated in aqueous solutions of increasing viscosity. Detailed flow dynamics associated with the nematode’s swimming motion as well as propulsive force and power are obtained using particle tracking and velocimetry methods. We find that C. elegans delivers propulsive thrusts on the order of a few nanonewtons. Such findings are supported by values obtained using resistive force theory; the ratio of normal to tangential drag coefficients is estimated to be approximately 1.4. Over the range of solutions investigated here, the flow properties remain largely independent of viscosity. Velocity magnitudes of the flow …