bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Modeling and System Identification of a Surface Marine Vehicle for Autonomous Swarm Applications
Authors: Xiros Nikolaos I. , Loghis Eleftherios K.
Published: October 2013

The scale model of a surface marine vehicle with electric propulsion by a dc motor and waterjet is built. The intention is to serve as prototype for dynamic modeling and system identification of a class of vehicles for autonomous swarm applications. A first step towards this end is to develop a mathematical model capable to adequately describe the motion of the vehicle under a variety of conditions. Such model is developed by fusing basic principles with data series obtained through a series of test basin experiments. The aim is to minimize the number and cost of sensors needed in this end, without unacceptably compromising accuracy, by employing knowledge of vehicle dynamics in order to form a customized gray-box modeling approach. A set of nonlinear differential equations, used to depict the behavior of the marine vehicle at hand are derived. This dynamic model will form the basis for applying physicomimetic approaches to control and navigation of a standalone or swarm of similar vehicles. In the physicomimetic controller synthesis approach, the control problem is tackled by the concept of virtual forces acting on the vehicle and in result generating motion patterns that are favored for a certain application, e.g. avoid obstacles and collisions. By the term virtual forces we refer to forces not actually existing but rather introduced to the system of interest through means of local-loop vehicle control. To achieve physicomimetic control one needs to effectively cancel the actual dynamics or physics to which a vehicle’s motion complies with and then impose the desired dynamics as virtual forces. In the present work, a series of open loop experiments will allow us to develop the actual dynamics of vehicle motion. At the same time, sensors will also provide active feedback required by the controllers to adjust the vehicle’s dynamic response and behavior so that it can be made compliant with an arbitrary virtual force at a later stage.
A Sealed System and Compressor Model for Optimal Control of Household Refrigerators
Authors: Abbasi Bahman , Wait Keith , Kempiak Michael
Published: October 2013

Increasingly stringent industry standards have posed significant challenges on manufacturers to enhance the design and performance of household refrigerators. One of the least expensive and most effective means of improving the system is optimizing the control strategy. Some of the most promising control systems, such as adaptive and optimal control methods, require an accurate model of the system to guide the control effort. However, the complexity and interconnectedness of thermal and refrigerant flow phenomena make developing modern control systems a particularly challenging aspect of designing refrigerators, in spite of many decades of research and development. There exist models to correlate the desired compartments’ temperatures to that of the evaporator coil. However, there is a lack of a general approach to translate the required evaporator temperature to a compressor speed that provides it in an energy efficient manner. This work introduces a method to make that connection. The technique developed in this work can be adjusted for implementation on various refrigerator sizes and platforms to help modulate and control the compressor speed in real time.
Modeling a Three-Axis Thermal MEMS Gyroscope
Authors: Zarei Nilgoon , Leung Albert M. , Jones John D.
Published: October 2013

This paper reports modeling of a three-axis thermal Micro-Electro-Mechanical System, MEMS, gyroscope through the use of the COMSOL Multiphysics software package. Being very small and having no movable parts makes the thermal MEMS gyroscope very reliable. Previously designed Thermal MEMS gyroscopes have the capability of detecting single-axis rotation. A three-dimensional finite-element model of the device has been developed to investigate three-axis rotation detection possibilities. The effect of gravity has been also investigated and we show techniques for suppressing this interference.
Dynamic Analysis of Large Specialty Glass Panels Under Ball Drop Impact — Numerical Modeling and Measurements
Authors: Chaparala Satish C. , Samala Praveen R. , Jacobs Joshua M. , Pesansky Jonathan D.
Published: October 2013

Response of brittle plate-like structures to impact loads (suddenly applied loads) has been the subject of many research studies. Specifically, glass used in various household, consumer electronics applications can be subjected to different kinds of impact loads. An ion-exchanged alumino-silicate glass developed by Corning Incorporated, also called Corning® Gorilla® Glass is used as cover glass for flat-panel televisions. One of the reliability tests that may be required for this application is that a steel ball of certain diameter is dropped from certain height at different locations on the glass panel mounted onto a frame. The requirement is that the glass should survive 2 J of impact energy at the center of the glass and 0.5 J of impact energy at the edges. These reliability requirements could change depending on the application and the customer. In this study, finite element analysis is carried out to understand the impact response of such glass panels. Experiments are conducted using strain gauges to measure the panel response at the center of glass with impacts up to 3.3 J. Finite element analysis results are then validated by comparing the predicted strain response with those of measurements.
Design Principles of the Thermal MEMS Gyroscope
Authors: Zarei Nilgoon , Leung Albert M. , Jones John D.
Published: October 2013

A micromachined gyroscope has been designed that measures rotation through the deflection of an oscillating stream of heated gas and its detection by symmetrically placed thermal sensors. Simulations of the physics of this device are used to show that its sensitivity is linearly proportional to the Ekman number of the gas stream.
High Performance MEMS Thermal Gyroscope
Authors: Zarei Nilgoon , Leung Albert M. , Jones John D.
Published: October 2013

This paper reports modeling a new design of Thermal MEMS gyroscope through the use of the Comsol Multiphysics software package. Being very small and having no movable parts have made thermal MEMS gyroscope very practical. Previously designed Thermal MEMS gyroscope shows some limitation such as being vulnerable to gravity force. Finding a technique to increase the range of thermal MEMS gyroscope reliability motivated us to come up with a new design that we will refer to as the ‘Forced Convection MEMS gyroscope’. A two-dimensional finite-element model of the device has been developed to investigate its performance. An external force has been introduced to the system to create a higher-velocity hot gas stream that will be deviated more in response to rotation. The external force should be great enough that convection currents resulting from gravity or acceleration will have minimal impact on the gyroscope sensitivity. A heating element can still be used, but its primary purpose is now to warm the flowing gas so that it can be detected by the sensors. In this paper we will also show that, in order to completely eliminate the impact of gravity and increase the sensitivity of the gyroscope, it is possible to eliminate the heaters entirely and instead use heated sensors to detect gas currents. In other words, the sensors are working as hot-wire anemometers. Our simulations suggest that this design variant results in higher sensitivity. We have also carried out optimization studies to identify the best location for the heaters and sensors.

A prototype of this device has been fabricated based on MEMS techniques, and an external pump is used to produce an oscillating gas flow within the device.
Dynamic Analysis of a Beam-Type Resonator With Off-Axis Attached Mass
Authors: Hassanpour Pezhman A. , Behdinan Kamran
Published: October 2013

In this paper, the model of a micro-machined beam-type resonator is presented. The resonator is a micro-bridge which is modeled using Euler-Bernoulli beam theory. A comb-drive electrostatic actuator is attached to the micro-bridge for the excitation/detection of vibrations. In the models presented in the literature, it is assumed that the center of mass of the comb-drive is located on the neutral axis of the beam. In this paper, it is demonstrated that this assumption can not be applied for asymmetric-shaped comb-drives. Furthermore, the governing equations of motion are derived by relaxing the above assumption. It has been shown that the off-axis center of mass of the comb-drive generates an amplitude-dependent transverse force in the beam, which is essentially a nonlinear effect. The governing equations of motion are solved using a hybrid analytical-numerical approach. The end application of the structure under investigation is in resonant sensing and energy harvesting applications.
Monitor for Information Alignment and Sustainability in Logistics Networks
Authors: Ferreira Jose , Agostinho Carlos , Ilie-Zudor Elisabeth , Jardim-Goncalves Ricardo
Published: October 2013

Globalization of manufacturing and the enlargement of production networks bear the problem of logistics. These worldwide non-hierarchical manufacturing and distributing networks are characterized by non-centralized decision making, thus increasing the autonomy of the hub organizations and enabling different rules and procedures for decision making within the same supply chain, but decreasing the effectiveness in terms of integration, interoperability, and transportation. The major cause for that is due to different systems and information structures. This paper suggests aligning the different enterprises operating within the network, using morphisms to relate and develop transformations between their information models and a common data exchange standard. Also, in order to manage the dynamism of internal information systems, a multi-agent framework is proposed to detect changes, being capable of reacting to sustain the interoperability-enabling morphisms.
High-Power Operation of Acoustic-Electric Power Feedthroughs Through Thick Metallic Barriers
Authors: Wilt K. R. , Scarton H. A. , Saulnier G. J. , Lawry T. J. , Ashdown J. D.
Published: October 2013

Throughout the last few years there has been a significant push to develop a means for the transmission of electrical power through solid metallic walls using ultrasonic means. The bulk of this effort has been focused on using two coaxially aligned piezoelectric transducers on opposite sides of a thick metallic transmission barrier, where one transducer serves as the “transmit” transducer and the other as the “receive” transducer. Previous modeling has predicted reasonably high power transfer efficiencies through the wall using this type of “acoustic-electric channel” to be possible at low power levels, which implies that channel component operates in a linear range with little concern of failure. High-power testing of two acoustic-electric channels has been done in an effort to determine power limits on such channels and to determine levels at which non-linear effects on the piezoelectrics become non-negligible. The tested channels are characterized by the “power density” imposed on the transmit transducer, that is, the power applied per unit area, as the values found for maximum power density are considered to be independent of transducer radii. The constructed channels are shown to be capable of transmitting large amounts of power (over 100 watts) without failure; and further, extrapolation of the results to channels with larger diameter transducers predicts power transfer of 1 kW to be highly feasible.
Numerical Simulation of Phase Change Material Composite Wallboard in a Multi-Layered Building Envelope
Authors: Zwanzig Stephen D. , Lian Yongsheng , Brehob Ellen G.
Published: October 2013

Residential buildings account for a large portion of total energy consumption in the United States. Residential energy usage can be dramatically reduced by improving the efficiency of building envelope systems. One such method is to incorporate thermally massive construction materials into the building envelope. This benefits building operation by reducing the energy requirement for maintaining thermal comfort, downsizing the AC/heating equipment, and shifting the peak load from the electrical grid. When impregnated or encapsulated into wallboard or concrete systems, phase change materials (PCMs) can greatly enhance their thermal energy storage capacity and effective thermal mass. In this work we numerically study the potential of PCM on energy saving for residential homes. For that purpose we solve the one-dimensional, transient heat equation through the multi-layered building envelope using the Crank-Nicolson discretization scheme. The latent heat storage of the PCM was accounted for with a phase fraction in a latent heat source term. Using this code we examine a PCM composite wallboard incorporated into the walls and roof of a typical residential building across various climate zones. The PCM performance was studied under all seasonal conditions using the latest typical meteorological year (TMY3) data for exterior boundary conditions. Comparisons were made between different PCM wallboard locations. Our work shows that there is an optimized location for PCM placement within building envelope surfaces dependent upon the resistance values between the PCM layer and the exterior boundary conditions. We further identified the energy savings potential by comparing the performance of the PCM wallboard against the performance of a building envelope without PCM. Our study shows that PCM composite wallboard can reduce the energy consumption in summer and winter and can shift the peak electricity load in the summer.
Chemically B-N Modified Activated Carbon and its Thermal Stability and Desorption Enthalpy With Methanol
Authors: Paul Rajib , Voskuilen Tyler , Zemlyanov Dmitry , Pourpoint Timothée L. , Fisher Timothy S.
Published: October 2013

A chemical modification of activated carbon is demonstrated through boron and nitrogen incorporation via microwave-assisted heating. The surface modification of the activated carbon was imaged by scanning electron microscope. The crystallinity of the material was quantified by X–ray diffraction, and the chemical content as well as bonding environment were investigated using X-ray photoelectron and Raman microscopies. The observed increment in desorption enthalpy of modified activated carbon with methanol as measured through differential scanning calorimetry and its superior thermal stability in air as measured by thermogravimetric analysis suggest that the modified material is a promising candidate for efficient sorption processes in waste thermal and solar energy driven cycles.
Equivalent Bending Stiffness of Laminated Composites Tubes With Polygonal Cross-Sections
Authors: Ho Meng-Hsien , Lu Xiaoyan , Tan Xinyuan , Chan Wen S.
Published: October 2013

Simple analytical solutions are developed for efficient computation of equivalent bending stiffness and ply stresses for n-sided regular polygonal cross-sections. The cross-sections investigated includes triangle, square, pentagon and hexagon for 3, 4, 5 and 6 sides, respectively. The analytical solution, based on Classical Lamination Theory, transformation matrices and parallel axis theorem, computes the in-plane stresses at each ply level of the laminate. Good agreement in comparison of results between analytical solutions and finite element results from ANSYS was achieved. This method represents an efficient tool for design engineers to perform parametric studies during the preliminary design phase.
Two-Phase Refrigerant Maldistribution in the Vertical Header and its Effect on the Heat Exchanger Performance as Evaporator in Heat Pump Mode
Authors: Zou Yang , Tuo Hanfei , Hrnjak Predrag S.
Published: October 2013

The vertical header is a usual feature of outdoor heat exchanger of the residential air-conditioning system, typically a multipass microchannel heat exchanger. When operating in heat pump mode, it functions as an evaporator. In such a system, refrigerant maldistribution in the header can deteriorate the performance of the heat exchanger. The objective of study in this paper is the adiabatic upward flow of the refrigerant in the second pass vertical header of microchannel heat exchanger and its effect on distribution. R410A is circulated into the header through the microchannel tubes (5 or 10 tubes) in the bottom pass and exits through tubes (5 or 10 tubes) in the top pass. Three circular headers were explored, each with the microchannel tubes inserted to half depth. The best distribution is found at high flow rate and low quality. The distribution is affected by the flow patterns in the header as well as axial momentum. A distribution correlation, obtained based on the flow rate measurement in each tube, was then incorporated with a microchannel heat exchanger model. The simulation results quantified the capacity reduction of the 2-pass microchannel condenser due to the refrigerant maldistribution.
Investigation of a High Temperature Packed Bed Sensible Heat Thermal Energy Storage System With Large Sized Elements
Authors: Kuravi Sarada , Trahan Jamie , Goswami Yogi , Jotshi Chand , Stefanakos Elias , Goel Nitin
Published: October 2013

A high temperature sensible heat thermal energy storage (TES) system is designed for use in a central receiver concentrating solar power plant. Air is used as the heat transfer fluid and solid bricks made out of a high storage density material are used for storage. Experiments were performed using a laboratory scale TES prototype system and the results are presented. The air inlet temperature was varied between 300°C to 600°C and the flow rate was varied from 50 CFM to 90 CFM. It was found that the charging time decreases with increase in mass flow rate. A 1D packed bed model was used to simulate the thermal performance of the system and was validated with the experimental results. Unsteady 1D energy conservation equations were formulated for combined convection and conduction heat transfer, and solved numerically for charging/discharging cycles. Appropriate heat transfer and pressure drop correlations from prior literature were identified. A parametric study was done by varying the bed dimensions, fluid flow rate, particle diameter and porosity to evaluate the charging/discharging characteristics, overall thermal efficiency and capacity ratio of the system.
Thermoelectric-Based Power Generator for Powering Microcontroller Based Security Camera
Authors: Dell Robert , Unnthorsson Runar , Wei C. S. , Sidebotham George W. , Jonsson Magnus Thor , Foley William , Ginzburg Eric , Paul Subashis , Kim Seyoon , Morris Anthony
Published: October 2013

This paper presents the design, implementation and evaluation of a thermoelectric-based point of use power generation system with no moving parts. The power system was designed to be robust and stable, capable of being clamped onto the outer wall of a hot steam pipe with a temperature of over 160°C using only heat pipes and natural convection of ambient air for cooling.

Several systems were built and tested. One system was built and tested at the Cooper Union in New York City. The power generation was evaluated for different ambient and steam pipe temperatures. The other systems were attached to an 85°C geothermal hot water pipe and a 100–120°C geothermal steam pipe in Iceland. The Cooper Union system was used to power two microcontroller based security cameras, one with wireless LAN and another with cellular connectivity. Additional testing of the PV voltage controller and the generator were conducted in Iceland.

The results show that the system can be used to power surveillance systems, even in remote locations without access to the electrical grid. Because the system does not require grid access, it will run constantly, and hence improve security. Furthermore, the unit’s power generation is greater in colder environments that substantially degrade battery performance.
Numerical Study of Sand Deposition and Control by Flat Solar Panels
Authors: Lan Chuanjin , Li Zhen , Ma Yanbao
Published: October 2013

To make the best use of solar energy, most solar plants are located in deserts or dry and sandy areas, where most of the sand originate in sandstorms and desertification. For large scale solar plants, the structure of the solar panels can reduce the mean wind speed greatly, thus having a great effect on the deposition and entrainment process of the sand and dust. To study the effect of installment of solar panels on wind flow, numerical simulations are applied to get the turbulent flow field in the lee of the solar panels, with inclination angles ranging from 15° to 30° and at different spacing. The results show that 30° is the optimal choice and the performance with larger spacing at 2.5 times panel length is better than the case at 1.5 times.
Evaluation of a Novel Anisotropic Conductive Adhesive Shear Under Multiple Tin-Lead and Lead-Free Reflow Cycles for Package-on-Package (POP) Assembly
Authors: D’Angelo Dustin , Ramkumar S. Manian , Wentlent Luke , Borgesen Peter
Published: October 2013

The continued desire for an alternative to lead-based solder materials for electrical interconnections has led to significant research interest in Anisotropic Conductive Adhesives (ACAs). These create bonds using a combination of metal particles and epoxies to replace solder. The novel ACA discussed in this paper allows for bonds to be created through aligning columns of conductive particles along the Z-axis. These columns are formed by the application of a magnetic field, during the curing process. The benefit of this novel ACA is that it does not require precise printing of the adhesive on pads and also enables the mass curing without creating shorts in the circuitry.

The novel ACA’s applicability for PCB-level assembly has been successfully demonstrated by RIT. The research at RIT has also characterized the base material properties, analyzed the effect of various process parameters, identified failures, and investigated the ACA’s long-term reliability for surface mount PCB assembly. Reliability testing included an investigation of the assembly performance in temperature and humidity aging, thermal aging, air-to-air thermal cycling, and drop testing conditions. For example, it has been shown that by modifying the filler particle size and coating, reliability of >1500 hours in high temperature, high humidity aging (HTHH), and 100 hours in highly accelerated stress testing (HAST) can be successfully achieved.

This paper highlights research comparing the shear loading performance of the novel ACA to that of tin-lead and lead free solders. Samples assembled with the adhesive and the solders were subjected to multiple tin-lead and lead free reflow cycles. The primary objective was to understand the deterioration in shear loading as influenced by multiple reflow cycles. Published research materials have shown the influence of the change in solder joint performance with multiple reflows due to the increase in intermetallic thickness. The results of a DOE study show the influence of the various factors and levels. Shear stress calculations indicate higher stress experienced by the adhesive joints as compared to the solder joints due to the spreading of the solder during wetting. Empirical relationships will be derived from the experimental data to help determine the required contact area for a given level of shear loading. The experimental results also reveal the rapid decrease in Shear stress between the first and second reflow and the slow decline in strength up to five reflows. Findings from this work will be used to assess the use and reliability of this adhesive for attaching the top component of Package-on-Package (PoP) 3D stacked components, in thermal cycling, HAST and HTHH environments.
Toward a Multi-Objective, Multi-Level Optimization Based Engineering Decision Tool
Authors: Shuttleworth Adam J. , Kelkar Atul
Published: October 2013

Prior to the acceptance of computer aided engineering (CAE) software in the product development process (PDP), product development was characterized by a design-test-redesign-test cycle. This activity was time consuming and resource intensive. As CAE software tools have been integrated into the PDP, the PDP has been characterized by a design-simulate-redesign-test cycle. The addition of CAE tools to the PDP has reduced the time to market and resource consumption. Although the benefits of the integration of CAE software in the PDP process have been realized, there still exists an arbitrary relationship between the results from the CAE tools to engineering decisions regarding product design.
Thermal Conductivity Performance Modeling and Characterization of a Novel Anisotropic Conductive Adhesive Used in Lead-Free Electronics Packaging
Authors: Combs Matthew J. , Ramkumar S. Manian , Kandlikar Satish
Published: October 2013

The continued desire to utilize an alternative to lead-based solder materials for electrical interconnections has led to significant research interest in Anisotropic Conductive Adhesives (ACAs). The use of ACAs in electrical connections creates bonds using a combination of metal particles and epoxies to replace solder. The novel ACA discussed in this paper allows for bonds to be created through aligning columns of conductive particles along the Z-axis. These columns are formed by the application of a magnetic field, during the curing process. The benefit of this novel ACA is that it does not require precise printing of the adhesive on pads and also enables the mass curing without creating shorts in the circuitry.

This paper will present the findings of the thermal conductivity performance tests using the novel ACA and its applicability as a thermal interface material and for assembling bottom termination components, power devices, etc. The columns that act as electrical conduction paths also contribute towards the thermal conductivity. The thermal conductivity of the novel ACA was measured utilizing a system that is similar to that in ASTM (American Society of Testing Materials) D5470 standard. The goal was to examine the influence of Bond Line Thickness (BLT), particle loading densities, particle diameters and adhesive matrix curing conditions on the electrical and thermal performance of the novel ACA. This paper will also present a numerical model to describe the thermal behavior of the novel ACA.

The novel ACA’s applicability for PCB-level assembly has also been successfully demonstrated by RIT, including base material characterization, effect of process parameters, failures, and long-term reliability. Reliability testing included the investigation of the assembly performance in temperature and humidity aging, thermal aging, air-to-air thermal cycling, and drop testing.
Injection Molding Process Windows Considering Two Conflicting Criteria: Simulation Results
Authors: Rodríguez Alicia B. , Niño Esmeralda , Castro Jose M. , Suarez Marcelo , Cabrera Mauricio
Published: October 2013

In this work, two criteria in conflict are considered simultaneously to determine a process window for injection molding. The best compromises between the two criteria are identified through the application of multiple criteria optimization concepts. The aim with this work is to provide a formal and realistic strategy to set processing conditions in injection molding operations. In order to keep the main ideas manageable, the development of the strategy is constrained to two controllable variables in computer simulated parts.
GyroCube: A Novice-Friendly Design and Simulation Tool for Gyroscopic Analysis and Optimization of MEMS
Authors: Jin Xing , Clark Jason V.
Published: October 2013

In this paper, we present an online design tool called GyroCube that greatly simplifies the parametric exploration of ready-made Micro Electro Mechanical Systems (MEMS) gyroscopes. GyroCube is able to perform gyroscopic analysis on nearly any MEMS structure imported from Sugar. In addition to Sugar’s existing MEMS solvers (i.e. frequency response, modal analysis, and transient analysis), we add gyroscope-specific analyses (i.e. quality factor, normalized sensitivity, natural frequency, stiffness, damping ratio). We also include geometry optimization given a user’s performance specification. We verify GyroCube’s results using finite element analysis and we demonstrate GyroCube’s ease of use.
Measurements of the Thermal Conductivity of Sub-Millimeter Biological Tissues
Authors: Lubner Sean D. , Choi Jeunghwan , Hasegawa Yasuhiro , Fong Anthony , Bischof John C. , Dames Chris
Published: October 2013

Accurate knowledge of the thermal conductivities of biological tissues is important for thermal bioengineering, including applications in cryopreservation, cryosurgery, and other thermal therapies. The thermal conductivity of biomaterials is traditionally measured with macroscale techniques such as the steady longitudinal heat flow method or embedded thermistor method. These techniques typically require relatively large, centimeter-scale samples, limiting their applicability to finer biological structures. They are also vulnerable to errors caused by thermal contact resistances and parasitic heat losses. In contrast, the thermal conductivity of inorganic solids such as semiconductor wafers and thin films is commonly measured using the “3 omega method” [1–3]. This frequency domain technique is robust against thermal contact resistances and parasitic heat losses. It routinely has sub-millimeter spatial resolution, with theoretical limits down to tens of microns. Here we adapt the 3 omega method for measurements of biological tissues. Thermal conductivity measurements are made on both frozen and un-frozen samples including agar gel, water, and mouse liver, including samples with sub-millimeter thicknesses. The measurement results compare favorably with literature values and span the range from around 0.5 to 2.5 W/m-K. This study demonstrates the promise that this technique holds for thermal measurements of bulk tissues as well as fine sub-millimeter samples.
Large Amplitude Vibrations of Completely Free Rectangular Plates
Authors: Alijani F. , Amabili M.
Published: October 2013

Nonlinear forced vibrations of completely free rectangular plates are studied using multi-modal Lagrangian approach. Nonlinear higher-order shear deformation theory is used and the nonlinear response to transverse harmonic excitation in the frequency neighborhood of the fundamental mode is investigated. Geometric imperfections are taken into account. The analysis is carried out in two steps. First, the plate displacements and rotations are expanded in terms of Chebyshev polynomials and a linear analysis is conducted to obtain the natural frequencies and mode shapes. Then, the energy functional is discretized by using the natural modes of vibration and a system of nonlinear ordinary differential equations with cubic and quadratic nonlinear terms is obtained. A pseudo arc-length continuation and collocation scheme is employed to carry out a bifurcation analysis. The effect of number of modes retained in the approximation, thickness ratio and geometric imperfections on the trend of nonlinearity is discussed.
A Study on the Dynamic Response in Standardized Drop Test
Authors: Kallolimath Sharan , Zhou Jiang
Published: October 2013

For past several years, industries are carrying out board level drop tests to calibrate JEDEC board and improve on simulation in order to quantify the solder joint reliability performance of their products. It has not only become a difficult to simulate exact drop condition but also a challenging task to capture some of the important parameters such as board flexural rigidity, stiffness, resulting in non-uniform strain distribution throughout the test board. Previous simulations reveal unreliable stresses on all 15 components during predominate mode, which resulted in grouping of the components by location for performing reliability analysis. In addition, current experimental test procedures are not only expensive but also time consuming. In order to reduce cost and time, predictive analytical models were developed to understand drop behavior and also the key factors effecting solder joint failures. The drop impact simulation was performed using the different pulse time duration input function by analytical Method and evaluate response characteristics of the JEDEC board system. In this paper parametric study is done in order to bring more realistic drop condition and to quantify stress /strain distribution throughout the test board independent from standoff region by analyzing the system as simplified continuous beam system with sine impact pulse with the consideration of singular value (predominate mode) of the natural frequency. In addition, FEA simulation is also performed by developing JEDEC global/local model to simulate the realistic drop test condition. Direct acceleration method is adopted and no ring phenomenon is validated. By adjusting the input pulse period from 1.0 to 2.5 times the system period reveal further increase in the maximum peeling stress and board surface strain due no ring effect. In order to match the current test case, the magnitude of board input acceleration is reduced to the current drop conditions to understand and improve in the efficiency of the test and to capture more stress strain data in all the components. Close forms of theoretical and analytical results were correlated with the results of current JEDEC finite element global model.
Silicon Interposer Featuring Novel Electrical and Optical TSVs
Authors: Thadesar Paragkumar A. , Bakir Muhannad S.
Published: October 2013

Three-dimensional (3D) integrated circuits (ICs) yield system level performance improvements by providing high-bandwidth communication as well as opportunity for heterogeneous integration. It is envisioned that an area array of 3D stacked ICs can be interconnected using dense fine-pitch electrical and photonic interconnects on a silicon interposer. This paper presents a mechanically robust “thick” silicon interposer with novel electrical through-silicon vias (TSVs) and optical TSVs. The novel electrical TSVs described include polymer-clad TSVs and polymer-embedded vias. An advantage of using thick silicon interposer is that microchannels can be integrated in the thick silicon interposer to transfer a coolant to the 3D ICs with interlayer microfluidic heat sink or for the direct integration of a microfluidic heat-sink in the silicon interposer. However, as the thickness of silicon interposer increases, TSV electrical parasitics increase. Moreover, the coefficient of thermal expansion (CTE) mismatch between the copper TSV and silicon causes reliability issues. To reduce TSV capacitance as well as to reduce TSV stresses, polymer-clad electrical TSVs were fabricated. Using the same photodefinable polymer used for the cladding of electrical TSVs, optical TSVs were fabricated and characterized.
Creep Strain Measurement of an Actual Leadfree Solder Interconnect Using Digital Image Correlation
Authors: Lee Hohyung , Park Seungbae
Published: October 2013

Creep behavior of the solder joint is one of the critical concerns in reliability of the electronic package, especially above half of the homologous temperatures. Considering melting point of the lead free solder alloys, creep deformation can be dominantly occur even at room temperature.

Among the three phase of the creep curve, the steady state strain rate in secondary phase is the most important design parameter to predict life time of the solder joint. To measure the strain rate of the solder during the creep deformation, several studies conducted creep test using bulk solder samples. However, mechanical properties of the bulk solder are different from actual solder joint due to its microstructure and intermetallic layer. Thus, creep behavior of the actual solder ball need to be measured to obtain the realistic creep data. In this study, the constant creep rate of the actual solder ball in ball grid array (BGA) packages is measured using 2D Digital Image Correlation (DIC) measurement technique.

Three lead free BGA packages, SAC105, SAC305 and Sn/Cu/Ni alloy (SCN) are used for the creep test. While 9.78 N, 19.56 N, and 29.34 N of the compressive loads are applied at 20°C, 40°C, 60°C and 90°C to each type of the specimen, a microscopic images of the cross sectioned surface of the solder ball are captured. The series of images are sequentially taken during the predetermined time interval and transferred to DIC software to generate full-filled surface displacement data. From the displacement data, constant creep rate of the actual solder ball is acquired.
A Flexoelectric Micro-Accelerometer
Authors: Huang Wenbin , Kwon Seol Ryung , Yuan Fuh-Gwo , Zhang Shujun , Jiang Xiaoning
Published: October 2013

In this paper new acceleration sensors using flexoelectric barium strontium titanate (BST) were designed, fabricated and tested for vibration monitoring. The flexoelectric sensors were configured as rectangular and trapezoidal cross-section micro-unimorphs with a BST layer bonded onto a Si substrate. Proof masses were attached to unimorph tips to amplify the transverse flexoelectric responses of the BST layers. The theoretical model was developed and validated by vibration tests using the prototyped flexoelectric micro-unimorphs. The prototyped accelerometer showed a stable sensitivity of 0.84 pC/g in the frequency range of 100 Hz ∼ 1.6 kHz, which agreed well with the analytical results. The aging property of the flexoelectric sensor was demonstrated to be much better than that of the reported piezoelectric materials right after poling. Scaling effect analysis was performed for flexoelectric unimorphs. The test results and initial scaling effect analysis indicate that micro/nano flexoelectric sensing hold promise for a broad range of applications.
Multi-Scale Transient Thermal Analysis of Microelectronics
Authors: Barabadi Banafsheh , Kumar Satish , Sukharev Valeriy , Joshi Yogendra K.
Published: October 2013

Thermal transport in microelectronic devices spans length scales from tens of nanometers to hundreds of millimeters. One of the major challenges in maintaining quality and reliability in today’s microelectronic devices comes from the ever increasing level of integration in the device fabrication as well as the high level of current densities that are carried through the microchip during operation. Consequently, significant opportunities for energy efficiency exist at various levels of the length scale hierarchy by optimization of thermal management resources.

In this study, we developed a computationally efficient and accurate multi-scale reduced order transient thermal methodology consisting of hybrid implementation of two different multi-scale approaches: 1. “Progressive Zoom-in” method and 2. “Proper Orthogonal Decomposition (POD)” technique. The suggested approach provides the ability to predict different thermal scenarios based on one representative thermal scenario, while maintaining the desired spatial and temporal accuracy. In this paper, a Flip Chip Ball Grid Array (FCBGA) package was considered for hybrid modeling. To demonstrate the capability of POD method in predicting different thermal scenarios, the chip is divided into ten function blocks. Each of these blocks had a different randomly generated dynamic power source. To validate this methodology, the results were compared with a finite element (FE) model developed in COMSOL®. The behavior of the POD model was in good agreements with the corresponding FE model. This close correlation provides the capability of predicting other thermal scenarios based on a smaller sample set which can significantly decrease the computational cost.
Design and Fabrication of Composite Wind Blades for a 5kW Wind Power System
Authors: Kam T. Y.
Published: October 2013

The development of composite wind blades for a 5kW wind turbine blade is presented. During the design process, the distributions of the twisting angle and wind load along the long axis of the blade are determined in the aerodynamic analysis of the blade. A finite element model is constructed for the design and stress analysis of the wind blade made of glass-fabric composites. The failure modes such as the first-ply failure and buckling of the skin of the composite wind blade are identified in the finite element analysis of the blade. The wind blade parts were fabricated using the hand-layup and vacuum-bag molding technique. The blade was composed of two, namely, upper and lower, composite skins which were joined together via a composite shear web. The wind blade was tested to validate the suitability of the design.
Comparative Evaluation of a Developed Batch Reactor Using Various Feedstock
Authors: Nwaigwe Kevin N. , Ogueke Nnamdi V. , Ugwuoke Paulinus E. , Anyanwu Emmanuel E.
Published: October 2013

The performance evaluation of a developed batch reactor using beniseed oil, fresh vegetable oil, and waste vegetable oil is presented. The transesterification process was used on samples of each feedstock at different reaction temperature and time while methanol and sodium hydroxide were used as the reagent and catalyst respectively. Optimum yield obtained at 55°C and 50 minutes gave the value of 1.65 litres of biodiesel for beniseed, 1.97 litres of biodiesel for fresh vegetable palm oil and 1.81 litres of biodiesel for waste vegetable palm oil. The yield of the by product (Glycerol) was maximum at the reaction time and temperature of 70 minutes and 60°C respectively. Characterization test results showed that the produced biodiesel has similar fuel properties with the conventional diesel and agrees with the ASTM standards for biodiesel. The outcome shows that the various feedstock are good sources for biodiesel production using the developed batch reactor.
The Application of Computational Fluid Dynamics for Installing the Roof-Mounted Wind Turbine
Authors: Lu Lu , Wang Xiuling
Published: October 2013

Purdue University Calumet (PUC) was planning to install a Vertical Axis Wind Turbine (VAWT) on the roof of Student Union and Library (SUL) building, an academic building on campus, for teaching and research purposes. While several potential sites have been identified as feasible, computational fluid dynamics (CFD) modeling and Virtual Reality (VR) visualization technology have been coupled to assist in assessing the optimal location for sitting the wind turbine. 3-D wind fields were constructed which take into account the neighboring building effects to the flow fields. Wind speeds, turbulent intensity, and aesthetic look are some of the factors used to make the final decision. After the installation, estimated power generation was calculated based on the wind turbine power output curve and statistical analysis of measured wind data.
Suppression of Instabilities in Low-Density Jets via Density-Profile Control
Authors: Bhattacharjee Sukanta , Acharya Sumanta
Published: October 2013

A numerical study is conducted to understand the global instability of very low-density jets (as encountered in thermal plasmas). The simulations have been carried out for different density ratios, S = ρj /ρ∞, ranging from 0.5 to 0.01, and different Reynolds numbers. The results show that the global instability mode exists in the range of density ratios investigated. A strategy for reducing the instability by altering the density profile of the surrounding gas stream is explored. Specifically, a ramp density profile or a step shape with an outward offset was studied, and it was observed that there was a reduction in the instability amplitude with the modified density profiles. Such a lowering in the instability fluctuations can be beneficial in stabilizing the thermal plasma behavior.
Energetic Operational Assessment of Two Small-Scale Trigeneration Plants
Authors: Badami Marco , Portoraro Armando
Published: October 2013

Trigeneration allows the thermal energy that is recovered from the prime mover of a cogeneration plant to be exploited to produce a cooling effect. In this way, when residential applications are considered, it is possible to extend the working hours of the plant over the heating period, providing the summer air conditioning. The paper is aimed at investigating the energetic performance of trigeneration, compared to cogeneration, dealing with the differences on prime mover efficiencies in the winter and the summer season. Two small-scale trigeneration plants have been considered: an internal combustion engine cogenerator capable of 126 kWel coupled to a liquid desiccant system, and a 100 kWel natural gas microturbine with an absorption chiller. The primary energy savings have been calculated, for both plant configurations, through a commonly accepted methodology proposed by the European Union, and through another methodology, reported in literature, which seems more appropriate to describe the energetic performances of trigeneration plants. A new performance indicator was then introduced by the Authors. The results are presented and discussed.
Numerical Simulation of Laminar Forced Convection Heat Transfer of Two Square Prisms Inside Nanofluids
Authors: Jayhooni S. M. H. , Nowzari M. H. , Jafarpur K. , Abbasi Baharanchi A.
Published: October 2013

Forced convection heat transfer for steady free stream flow past two isothermal prisms inside different nanofluids has been studied numerically. Nanofluids have been consisted of Al2O3 and CuO nanoparticles with different particle diameters (dnp = 30nm and 100nm) and different particle volumetric concentrations (0% < φ < 4%). Besides, water is used as base fluid for all nanofluids. In this research the recent correlations are used for viscosity and thermal conductivity of nanofluids. The correlations are function of temperature and particle volumetric concentration. The present numerical simulations have been performed for Pe < 200 in which the flow is steady and laminar. The results show that the heat transfer coefficients for all nanofluids are higher than the base fluid (water). These enhancements are more considerable in high Peclet numbers and high particle volumetric concentrations. In addition, among the tested nanofluids, the CuO/water with 4% particle volumetric concentration and 100nm particle diameter finds to be the best nanofluid to increase the heat transfer. The effect of nanofluids on increasing heat transfer is lower for second prism as compared with the first one.
Effects of Corner Cutoffs on Flow Past Two Square Cylinders in a Tandem Arrangement
Authors: Krishne Gowda Y. T. , Ravindra H. V. , Vikram C. K.
Published: October 2013

Flow past the two square cylinders with and without corner modification in a tandem arrangement has been simulated using a CFD code FLUENT. A Reynolds number of 100 and pitch to perimeter ratios (PPR) of 2,4 and 6 are considered for the investigation. The flow is assumed to be two dimensional unsteady and incompressible. The obtained results are presented in the form of streamlines, pressure distribution, monitored velocity, lift coefficient and Strouhal number. Results indicate, in case of chamfered and rounded corners, there is decrease in the wake width and thereby the lift values. For the square cylinders of same perimeters with and without corner modification, the size of the eddy and the monitored velocity in between the square cylinders increases with increase in PPR. Frequency of vortex shedding is same in between the cylinders and in the downstream of the cylinder. Frequency of vortex shedding decreases with the introduction of second cylinder either in the upstream or downstream of the first cylinder. The lift coefficient of square cylinder with corner modification decreases but Strouhal number increases when compared with a square cylinder without corner modification.