bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid Flow Behavior for a Confined Rotating MCM Disk With Round Jet Array Impingement
Authors: Fang C. J. , Lee C. Y. , Peng C. H. , Lin T. W. , Hung Y. H.
Published: January 2010

A series of experimental investigations on the studies related to fluid flow characteristics of a confined rotating Multi-Chip Module (MCM) disk with round air jet array impingement have been performed. The relevant parameters influencing fluid flow characteristics include the ratio of jet separation distance to nozzle diameter (H/d), jet Reynolds number (Rej) and rotational Reynolds number (Rer). The parametric ranges are Rej = 712 – 4087, Rer = 0 – 2906, H/d = 0.83–14.4 and Z/d = 1–7. The potential core lengths of all the nozzle jets increases with increasing jet Reynolds number or H/d ratio and decreases with increasing rotational Reynolds number. New correlations of the ratio of potential core length to nozzle diameter at various nozzle jets in terms of relevant influencing parameters are proposed. Furthermore, the strengths on both streamwise velocity and turbulence intensity increase with increasing Z/d ratio. The turbulence intensity for the cases of jet array impingement growing up along the axial directions are significantly faster than the cases of single round jet impingement. The jet array impingement has a higher momentum flux in the flow interaction region between two adjacent nozzles; accordingly, it can achieve a more uniform thermal performance as compared with the cases of single round jet impingement. Near-surface fluid flow behavior including the streamwise velocity and turbulence intensity distributions can be employed to interpret the heat transfer characteristics for jet array impingement.
Temperature Dependent Phonon Lifetimes and Decay Pathways in Hexagonal Gallium Nitride
Authors: Beechem Thomas , Graham Samuel
Published: January 2010

The decay rate of phonons is known to affect gallium nitride (GaN) based device performance. Hence understanding the dynamical behavior of the phonons in GaN is integral to improvement of these promising devices. Using the energy-time uncertainty relation, this work examines the temperature dependency of the phonon lifetimes in GaN. By examining this temperature dependency, both decay mechanisms and energy pathways are deduced through use of previously developed scattering models used in concert with a novel graphical approach which allows mapping of the phonon decomposition.
Assessment and Improvement of the Thermal Performance of a Polycarbonate Micro Continuous Flow Polymerase Chain Reactor (CFPCR)
Authors: Chen Pin-Chuan , Mitchell Michael W. , Nikitopoulos Dimitris E. , Soper Steven A. , Murphy Michael C.
Published: January 2010

BioMEMS are compact devices that use microfabrication to miniaturize benchtop instrumentation. Due to the requirement for uniform temperature distributions over restricted areas, thermal isolation, and faster heating and cooling rates in a limited space, thermal management is a key to ensuring successful performance of BioMEMS devices. The continuous flow polymerase chain reactor (CFPCR) is a compact BioMEMS device that is used to amplify target DNA fragments using repeated thermal cycling. The temperature distribution on the backside of a micro CFPCR was measured using thermochromic liquid crystals and an infrared camera. In the liquid crystal experiment, the performance of a 5 mm thick polycarbonate micro CFPCR with thin film heaters attached directly to the bottom polycarbonate surface over each temperature zone was studied. Natural convection was used as a cooling mechanism. The temperature distribution in the renaturation zone was dependent on the positions of the feedback thermocouples in each zone. Three different thermocouple configurations were assessed and the liquid crystal images showed that a best case 3.86°C temperature difference across the zone, leading to a 20% amplification efficiency compared to a commercial thermal cycler [5]. The device was modified to improve the temperature distribution: a thinner substrate, 2 mm, reduced the thermal capacitance; grooves were micro-milled in the backside to isolate each temperature zone; and three separate copper heating stages, combining the thin film heaters with copper plates, applied uniform temperatures to each zone [10]. Infrared camera images showed that the temperature distributions were distinct and uniform with a ±0.3 °C variations in each temperature zone, improving amplification efficiency to 72%. Good thermal management for PCR amplification can’t only increase its reliability and yield efficiency, but also accelerate the entire analytical process.
A Study on Repetitive Drop Test Method and for Electronic Component
Authors: Yu Qiang , Fujita Masato , Shibata Tsuyoki , Katahira Takayoshi , Shiratori Masaki
Published: January 2010

In recent years, mobile phones have been miniaturized, so electronic components with high I/O count have been changed from QFP/SOIC to BGA/LGA. However BGA/LGA tends to have weak reliability for drop impact, and the drop reliability needs to be improved. For that, board level drop reliability has an important role in order to evaluate drop reliability for electronic components excluding influence from phone mechanics. This study focuses on the characterization of the test methods using experimental test, strain analysis and FEM simulation. In this paper, board level drop test shows drop a fixture with a component assembled on PWB. The drop test using a fixture with a flat bottom lacked of repeatability of failed drop count, and it was improved by adding hemisphere at the center on fixture bottom to reduce the influence by variation of falling posture angle, and strain analysis and the drop experimental proved it, too. The deformations of the fixture influence the test results, because the deformation of fixture caused high stress on solder joints. For that, the method to exclude the influence of fixture deformation was studied, and it was found that the influence can be decreased by supporting condition of PWB with a free-sliding end or the new design of the fixture. On the other hand, the effect of height of drop, mass of fixture, and supporting condition on the drop test, can be thought as the acceleration factors for the dropping load conditions. The drop tests were done in many load conditions. The results were analyzed by strain analysis and FEM simulation. As a result, an accelerating ratio can be evaluated by predicting the effect of these factors, and effective dropping test can be conduct without increasing the dropping height exceedingly.
Comparison of Thermal Performance of Current High-End Thermal Interface Materials
Authors: Refai-Ahmed Gamal , He Zhaojuan , Heian Ellen , Vincent Ramzi , Rude Tim , Van Heerden David
Published: January 2010

Reactive NanoTechnologies (RNT) has developed a reactive bonding technology to directly bond silicon dies to heat sinks with indium solder using a reactive multilayered foil. In this new method of bonding, heat is generated locally by exothermic mixing within the multilayered foil. This heat is used to melt indium solder layers to join the dies to the heat sinks. The measured thermal resistance of the resulting solder bond is 4 to 5 K mm2/W (0.006 to 0.008 K in2/W). In addition, the reactive foil also localizes the heat to the interface, thus minimizing residual stress and thermal damage in the components. In this paper we discuss the thermal performance and reliability test results for reactive multilayer bonding with different bond line thicknesses. We also present detailed comparisons of thermal performance between reactive multilayer bonding and other current Thermal Interface Material (TIM) solutions, including polymer-based greases, phase change materials, and low melting metallic alloy. Benchmark tests were done using the graphics processor on an operational video card as a test vehicle. The test results show that the introduction of a reactive multilayer bond as an interface material between the graphics processor and the thermal management device demonstrates significant performance advantages over any of the other current commercially available TIM solutions.
Co-Flowing Ammonia Desorption in a Fractal-Like Branching Heat Exchanger
Authors: Mouchka Greg , Apreotesi Mario , Davis Keith , Pence Deborah
Published: January 2010

Heat activated cooling provides an opportunity to recover and utilize wasted heat. In terms of thermal management of electronics, a heat-activated cooling cycle could be used to thermally manage a space such as a central computing facility. A microscale, fractal-like branching flow heat exchanger was designed and used to desorb ammonia from an aqueous ammonia solution. The fractal-like pattern employed in the present study was previously studied for high heat flux single-phase and two-phase boiling flow heat sink applications. For compatibility, the desorber was fabricated in 316 stainless steel. The desorber is compact, approximately 38 mm in diameter and 6.4 mm thick, and lightweight, weighing 20 grams. Heating was accomplished using Paratherm NF oil between 350 and 400 K. The mass fraction of ammonia in the strong solution inlet stream was 0.30 and the temperature was 300 K. Given a range of inlet solution mass flow rates between 0.42 and 0.92 g/s and oil flow rates between 1.67 and 10 g/s, the mass flow rate of vapor generated varied from 0.02 to 0.13 g/s. The mass fraction of ammonia in the exiting vapor stream varied between 0.8 and 0.96 while circulation ratios varied between 3.5 and 20. Heat exchanger performance is presented using LMTD and ε-NTU analyses. Overall heat transfer coefficients ranged from 7500 to 15,000 for the flow rates and driving temperature differences investigated. The configuration of the desorbers is such that the oil stream can be introduced to flow parallel or counter to the ammonia solution stream. The nature of the microchannels is such that desorption occurs in a co-flowing manner, limiting the vapor mass fraction. However, the advantages of the present design are lightweight, compact, modularity and orientation independence.
Decoupled Thermal and Fluidic Effects on Hotspot Cooling in a Boiling Flow Microchannel Heat Sink
Authors: Flynn Roger , Cheng Ching-Hsiang , Goodson Kenneth
Published: January 2010

Heat sinks for next generation microprocessors must remove increasing levels of power with non-uniform spatial distribution (hotspots). Two-phase convection promises strongly reduced pump size but is challenging because of boiling flow instabilities. This work studies parallel microchannel boiling stability using a series of dual channel devices which are fabricated with varying lateral thermal resistance and integrated heaters and thermometers. The data are consistent with a demand curve analysis predicting flow distribution and wall temperatures in thermally isolated parallel channels with strictly fluidic interaction. Increasing the thermal resistance between two parallel channels is shown to strongly influence the onset of instabilities and adversely increase the peak temperature. These dual-channel experiments capture the key physics of multichannel instabilities and provide the foundation for improved design of two-phase microfluidic heat sinks.
Quality Inspection of Flip Chip Solder Bump Using Analytical, Numerical and Experimental Modal Analyses
Authors: Yang Jin , Ume I. Charles
Published: January 2010

Solder bump inspection of surface mount packages has been a crucial process in the electronics manufacturing industry. A novel solder bump inspection system has been developed using laser ultrasound and interferometric techniques. In this research, modal analysis is important to correlate the defects with dynamic responses of packaged electronic devices. The effect of solder bump defects on the mode frequencies and mode shapes is investigated in this paper. The objective is to develop a modal analysis approach integrating analytical, numerical and experimental methods. In particular, this paper discusses the analytical modeling, numerical modeling, and out-of-plane vibration experiment for a 6.35mm×6.35mm×0.6mm non-underfilled PB18 flip chip on a FR4 board.
Die Stress Variation During Thermal Cycling Reliability Tests
Authors: Rahim M. Kaysar , Roberts Jordan , Suhling Jeffrey C. , Jaeger Richard C. , Lall Pradeep
Published: January 2010

Thermal cycling accelerated life testing is an established technique for thermo-mechanical evaluation and qualification of electronic packages. Finite element life predictions for thermal cycling configurations are challenging due to several reasons including the complicated temperature/time dependent constitutive relations and failure criteria needed for solders, encapsulants and their interfaces; aging/evolving material behavior for the packaging materials (e.g. solders); difficulties in modeling plating finishes; the complicated geometries of typical electronic assemblies; etc. In addition, in-situ measurements of stresses and strains in assemblies subjected to temperature cycling are difficult because of the extreme environmental conditions and the fact that the primary materials/interfaces of interest (e.g. solder joints, die device surface, wire bonds, etc.) are embedded within the assembly (not at the surface). For these reasons, little is known about the evolution of the stresses, strains, and deformations occurring within sophisticated electronic packaging geometries during thermal cycling. In this work, we have used test chips containing piezoresistive stress sensors to characterize the in-situ die surface stress during long-term thermal cycling of electronic packaging assemblies. Using (111) silicon test chips, the complete three-dimensional stress state (all 6 stress components) was measured at each rosette site by monitoring the resistance changes occurring in the sensors. The packaging configuration studied in this work was flip chip on laminate where 5 × 5 mm perimeter bumped die were assembled on FR-406 substrates. Three different thermal cycling temperature profiles were considered. In each case, the die stresses were initially measured at room temperature after packaging. The packaged assemblies were then subjected to thermal cycling and measurements were made either incrementally or continuously during the environmental exposures. In the incremental measurements, the packages were removed from the chamber after various durations of thermal cycling (e.g. 250, 500, 750, 1000 cycles, etc.), and the sensor resistances were measured at room temperature. In the continuous measurements, the sensor resistances at critical locations on the die device surface (e.g. die center and die corners) were recorded continuously during the thermal cycling exposure. From the resistance data, the stresses at each site were calculated and plotted versus time. The experimental observations show cycle-to-cycle evolution in the stress magnitudes due to material aging effects, stress relaxation and creep phenomena, and development of interfacial damage.
Thermal Performance Measurements of Thermal Interface Materials Using the Laser Flash Method
Authors: Khuu Vinh , Osterman Michael , Bar-Cohen Avram , Pecht Michael
Published: January 2010

Thermal interface materials are used to reduce the interfacial thermal resistance between contacting surfaces inside electronic packages, such as at the die-heat sink or heat spreader-heat sink interfaces. In this study, the change in thermal performance was measured for elastomeric gap pads, gap fillers, and an adhesive throughout reliability tests. Three-layer composite structures were used to simulate loading conditions encountered by thermal interface materials in actual applications. The thermal resistance of the thermal interface material, including contact and bulk resistance, was calculated using the Lee algorithm, an iterative method that uses properties of the single layers and the 3-layer composite structures, measured using the laser flash method. Test samples were subjected to thermal cycling tests, which induced thermomechanical stresses due to the mismatch in the coefficients of thermal expansion of the dissimilar coupon materials. The thermal resistance measurements from the laser flash showed little change or slight improvement in the thermal performance over the course of temperature cycling. Scanning acoustic microscope images revealed delamination in one group of gap pad samples and cracking in the putty samples.
Thermal Characterization of Micro-Channels Heat Exchanger for High-End Processors
Authors: Sheltami Khalid , Refai-Ahmed Gamal
Published: January 2010

With the market demand of more performance at smaller form factors, the technology direction is moving into increasing the transistors in semiconductor devices by a significant percentage, which translates into increasing the heat flux by a substantial amount. Thermal management of these devices, within a compact form factors, at an acceptable junction temperature, is a challenging task for the industry and researchers alike. This paper presents the significant increase in cooling capacity by using micro-channels technology in liquid cooling and highlights the advantages of this solution over macro-channels. The current study has examined the effects of both the channel width and its wall thickness on the heat transfer coefficient and hydraulic impedance. The present investigation is supported by CFD simulations and experimental results. The preliminary results of this study show that micro-channels technology could improve the heat exchanger performance by 64%. Finally, this paper proposes an empirical model to account for the effects of the geometric parameters of the heat exchanger on its thermal performance, as well as, its hydraulic characteristic.
Thermo-Viscoelastic Analysis for Warpage in CSP With Different Viscoelastic Properties for Several Layers
Authors: Koguchi Hideo , Ueno Atsushi
Published: January 2010

In this study, a simple theory for estimating the warpage of chip size packaging (CSP) during a manufacturing process is presented. A single-sided CSP which is composed of IC, a resin and a substrate is modeled for an analysis as a three-layered material. Especially, the resin and the substrate have different thermo-viscoelastic properties. When the layered body is perfectly bonded, its warpage is caused by the difference of the thermal expansion coefficient in each layer when temperature varies. The warpage of CSP for a various thicknesses of the IC and the substrate is investigated. Finally, the warpage calculated using the theory is compared with the result in experiment, and both results are well agreed with each other. Then, it is shown that the simple theoretical analysis is valid. After that, this program is extended to be able to analyze the warpage in a CoC (Chip on Chip), and the result of the analysis is then presented.
Taguchi Robust Analysis of Fatigue of Lead-Free Sn3.5Ag Solders
Authors: Lin Heng Cheng , Kung Chieh , Chen Rong Shen
Published: January 2010

This paper presents a study of the effects of selected geometry features on the fatigue life of the Sn3.5Ag lead-free solder ball on a multi-chip module (MCM) package. The features considered are both the upper and lower solder pad radii, the thickness of the substrate and that of the PC board. The components constituting the MCM include a heat spreader, thermal adhesive, chips, an underfill/Sn3.5Ag lead-free solder bumps mixture, structural adhesive, a substrate, a PC board, and Sn3.5Ag lead-free solder balls. To account for the time- and temperature-dependent behavior of the lead-free solders, a multi-linear isotropic hardening rule and a creep constitutive relation are considered. Linear elastic models are assumed for the rest components. In this study, the Surface Evolver is employed to determine the shape, including the height and pad radii, of the solder ball. A sliced 3D model is proposed using the finite element method to demonstrate the structural responses of the package subjected to ten temperature cycles between the high dwell temperature of 125°C and the low of −40°C. The structural responses of interest are deformation, stress distribution, and strain range of the solder ball having the greatest distance from the neutral point (DNP). A modified Coffin-Manson fatigue model is adopted to calculate the fatigue life cycle for the solders. In the course of the study, a parametric analysis is firstly conducted to characterize the influence of the geometry features on the fatigue life of the solders. An analysis of variation based on the Taguchi robust method is then exploited to investigate the optimal design for the fatigue life of the solders. Our results show that due to the mismatch of the coefficients of thermal expansion of the components, local deformations that do not comply with the global deformation are realized. Both the upper and lower pad radii have an opposite effect on the fatigue life of the solders. The fatigue life of the solders decreases as the thickness of the substrate or the PC board increases. The results using the Taguchi method reveal that among the four selected geometry features, both the upper pad radius and the PC board thickness are the most dominating factors. An optimal combination of the four features is recommended. This combination of the four features yields a fatigue life of 843 cycles that is a gain of 7.88 times of that of a reference package model.
Microstructural Change of Sn/37Pb and Sn/3Ag/0.5Cu Solder Alloys Subjected to Uniaxial Ratchetting Deformation
Authors: Sasaki Katsuhiko , Kobayashi Takuji , Ohguchi Ken-Ichi
Published: January 2010

Ratchetting deformations of solder alloys are significant deformations for the safety and reliability of solder joints of electronic packaging. In this paper, the microstructural change of the solder alloys due to the uniaxial ratchetting deformation is evaluated to clarify the effect of the microstructure on the viscous deformation of solder alloys. The microstructures are observed after the specimens are subjected to the uniaxial ratchetting deformation during several cycle numbers. The change of the size of grains or lamella structures is used to evaluate the uniaxial ratchetting deformation of solder alloys. The observation clarifies that the differences in the microstructural change due to the uniaxial ratchetting deformation between the lead-free and lead-containing solder alloys. The uniaxial ratchetting deformation and the additional creep deformation after the ratchetting deformation is also simulated by the dislocation based constitutive model. The simulation suggests that the material parameters used in the constitutive model may be correlated to the microstructural change of the solder alloys.
A Numerical Comparison of 2D and 3D Unsteady Confined Impinging Air Jets and Associated Microelectronics Cooling Impact
Authors: Chiriac Victor Adrian , Rosales Jorge Luis
Published: January 2010

A numerical investigation to compare the flow and heat transfer characteristics of 2D and 3D single impinging slot jets was performed at various Reynolds numbers. The present study is a continuation of the authors’ earlier work [1], and identifies the main similarities and differences arising from the expansion to the third dimension. For comparison purposes, a single slot jet impinges on an adiabatic lower wall with a flush mounted heat source. Two Reynolds numbers have been selected, 300 and 600, such that the jets are steady at the lower Reynolds number flow for both 2D and 3D models and unsteady for the higher Reynolds number flow. Both simulations are in the laminar regime. The steady cases at a Reynolds number of 300 show that the 3D slot jet produces the same values as the 2D case. The flow produces a symmetrical, steady flow hydrodynamic pattern with the jet being deflected laterally by the wall. By further increasing the Reynolds number to 600, a complex and highly unsteady flow develops for both 2D and 3D simulations. The complex flow patterns reveal the vortex pairing effects observed before for the 2D flows, leading to the jet “buckling and sweeping” behavior. However, the 3D unsteady jet produces results that deviate from the 2D unsteady case due to 3D viscous effects that are more pronounced than for the steady flow. The relevant difference between the 3D spatial behavior versus the 2D planar behavior occurring for the unsteady flows are documented by comparing the Nusselt numbers on the target wall for the cases under evaluation. Plots of the velocity, vorticity and temperature fields for both 2D and 3D cases are provided together with detailed discussion of the results.
Fluid Flow and Heat Transfer Over a Micro-Sphere
Authors: Antar M. A.
Published: January 2010

Due to the increased power dissipation for the new generation of microprocessors, cooling technologies represent a challenge to the manufacturers of such components. This is especially true as the component size is getting smaller and hence the heat generated per unit area is increasing significantly. Moreover, the importance of the microscale fluid flow rises from the new applications of micro-scale electromechanical systems that encounter fluid flow, such as micro-pumps, micro-turbines and micro-robotics. An understanding of the basic flow field and heat transfer in the case of external flow around miniature components is an essential tool to find proper means for cooling these small electronic/electromechanical devices. This work introduces a fundamental investigation of the external flow field and heat transfer characteristic around a micro sphere. In this study, the fluid flow and forced convection heat transfer characteristics over a micro-sphere at moderate to high values of Reynolds number are numerically investigated. The classical boundary condition of uniform wall temperature is considered in this work. In spite of the significance of this topic in understanding the basic flow and heat transfer features about a miniature sphere, it received little attention in the open literature. In this model, the effect of the engineering parameters such as Reynolds number and Knudsen number on the velocity and temperature profiles are investigated. The numerical code has the capability of accurate determination of the angle of external flow separation. The Knudsen number values used are limited by the continuity range where the Navier-Stokes Equations are used. Therefore, The Knudsen number is assumed small enough to apply a continuum model for the flow field with a temperature jump and frictional slip at the sphere’s surface.
Enhanced Thermoelectric Cooler for On-Chip Hot Spot Cooling
Authors: Wang Peng , Bar-Cohen Avram , Yang Bao
Published: January 2010

Due to shrinking feature size and increasing transistor density, combined with the performance demanded from next-generation microprocessors, on-chip hot spots, with their associated high heat fluxes and sharp temperature gradients, have emerged as the primary driver for thermal management of today’s IC technology. This paper describes the novel use of thermoelectric coolers for on-chip hot spot cooling through the use of a copper mini-contact pad, which connects the thermoelectric cooler and the silicon chip thus concentrating the thermoelectric cooling power. A package-level numerical simulation is developed to predict the local on-chip hot spot cooling performance which can be achieved with such mini-contacts. Attention is focused on the hot spot temperature reduction associated with variations in mini-contact size and the thermoelectric element thickness, as well as the parasitic effect of the thermal contact resistance introduced by the mini-contact enhanced TEC. This numerical model and simulation results are validated by comparison to spot cooling experiments with a uniformly heated chip serving as the test vehicle. The experimental results demonstrate that a copper mini-contact pad can improve spot cooling performance by 80 ∼ 115% on a 500μm thick silicon chip under optimum operating conditions and that larger power dissipation on the chip leads to better spot cooling performance.
Transient-Response Spectral Analysis Based Feature Extraction for Built-In Reliability Test of Electronics Under Shock Loads
Authors: Lall Pradeep , Choudhary Prakriti , Gupte Sameep , Gupta Prashant , Suhling Jeff , Hofmeister James
Published: January 2010

The built-in stress test (BIST) is extensively used for diagnostics or identification of failure. The current version of BIST approach is focused on reactive failure detection and provides limited insight into reliability and residual life. A new approach has been developed to monitor product-level damage during shock and vibration. The approach focuses on the pre-failure space and methodologies for quantification of failure in electronic equipment subjected to shock and vibration loads using the dynamic response of the electronic equipment. Presented methodologies are applicable at the system-level for identification of impending failures to trigger repair or replacement significantly prior to failure. Leading indicators of shock-damage have been developed to correlate with the damage initiation and progression in shock and drop of electronic assemblies. Three methodologies have been investigated for feature extraction and health monitoring including development of a new solder-interconnect built-in reliability test, FFT based statistical-pattern recognition, and time-frequency moments based statistical pattern recognition. The solder-joint built-in-reliability-test has been developed for detecting high-resistance and intermittent faults in operational, fully programmed field programmable gate arrays. Frequency band energy is computed using FFT and utilized as the classification feature to check for damage and failure in the assembly. In addition, the Time Frequency Analysis has been used to study of the energy densities of the signal in both time and frequency domain, and provide information about the time-evolution of frequency content of transient-strain signal. Closed-form models have been developed for the eigen-frequencies and mode-shapes of electronic assemblies with various boundary conditions and component placement configurations. Model predictions have been validated with experimental data from modal analysis. Pristine configurations have been perturbed to quantify the degradation in confidence values with progression of damage. Sensitivity of leading indicators of shock-damage to subtle changes in boundary conditions, effective flexural rigidity, and transient strain response have been quantified. Explicit finite element models have been developed and various kinds of failure modes have been simulated such as solder ball cracking, package falloff and solder ball failure. This allows the physical quantification of solder ball crack damage in the form of confidence values and provides a damage index that can be utilized for the health monitoring of solder interconnects in an electronic assembly.
A Fundamental Approach to Modeling Transport to an Impinging Spray
Authors: Ashwood Andrea C. , Lane Curtis , Regner Benjamin M. , Shedd Timothy A.
Published: January 2010

This work presents an integrated approach to the modeling of the liquid film resulting from spray impingement. First, fundamental, micro-scale behaviors within the liquid film are investigated with a CFD simulation using a volume-of-fluid model. The mean velocity profile in the liquid film created by a stream of impacting droplets in this simulation are extracted and non-dimensionalized, and then used in the integral conservation equations for mass and momentum in the liquid film to create a 1-D numerical model of the system. An experiment is designed to obtain mean shear stress due to impinging sprays/jets, and the results are compared with the numerical model. Excellent agreement is observed using just one fitting parameter in the numerical model, and this fitting parameter appears to take on physically relevant values.
Heat Pipes for High Temperature Thermal Management
Authors: Sarraf David B. , Anderson William G.
Published: January 2010

Copper water heat pipes are a well-established solution for many conventional electronics cooling applications; however they have several problems when applied to high temperature electronics. The high vapor pressure of the working fluid combined with the decreasing strength of an already soft material leads to excessive wall thickness, high mass, and an inability to make thermally useful structures such as planar heat pipes (vapor chambers) or heat pipes with flat input surfaces. Titanium/water and Monel/water heat pipes can overcome the disadvantages of copper/water heat pipes and produce a viable thermal management solution for high temperature electronics. Water remains the fluid of choice at temperature up to about 280°C due to its favorable transport properties. Life tests have shown compatibility at high temperature. At temperatures above roughly 300°C, water is no longer a suitable fluid, due to high vapor pressure and low surface tension as the critical point is approached. At higher temperatures, another working fluid/envelope combination is required, either an organic or halide working fluid. Preliminary halide life test results are presented, giving fluids that can operate at temperatures as high as 425°C. At higher temperatures, alkali metal heat pipes are suitable. Water and the higher temperature working fluids can offer solutions for cooling high-temperature electronics, or those working at or above 150°C.
Process Development and Die Shear Testing in MOEMS Packaging
Authors: Lakhkar Nikhil , Fasoro Abiodun , Patil Amit , Lee Woo Ho , Popa Dan , Agonafer Dereje , Stephanou Harry
Published: January 2010

Micro-Opto-electro-Mechanical Systems (MOEMS), which are MEMS integrated with photonics, share the traditional challenges of MEMS packaging with the additional issues of optical interconnects and optical surface contamination. Optoelectronic systems require signals through a package using fiber-optics, coaxial or other interconnection approaches. Precise optical component alignment and accurate thermal management is critical to achieve component and system performance capabilities. As the requirements for higher signal speeds and higher data rates grow, and as operating frequencies move to the higher GHz regions and beyond, the choice of packaging technology becomes critical. Optical MEMS packages not only have to provide electrical connections but also support high precision optics and mechanics, vital for operation of optical MEMS devices. Analogous to MEMS, packaging is also a critical path in reliability and cost of MOEMS devices. One of the commonly observed failures is the de-lamination between the chip (die) and the die attach. The focus of this paper is the development of a reliable fluxless die attachment process suitable for MOEMS assemblies with long operational life time. The reliability assessment was carried out at the Texas Microfactory™ at UT Arlington according to the MIL-STD-883F for die shear reliability.
Student diversity and the persistence of gender effects on conceptual physics learning
Authors: Noack A. , Antimirova T. , Milner-Bolotin M.
Published: January 2010

At Ryerson University every year, hundreds of science and engineering students enroll into required introductory physics courses. The diverse educational histories and demographic characteristics of these students reflect the diversity of Toronto as an urban metropolis and Canada more generally. In this study, we investigate how students’ demographic and educational diversity affects their conceptual learning in introductory university physics. As expected, we found that the completion of a senior high school physics course is positively related to students’ initial conceptual understanding of physics. The unexpected result was that gender remained a predictor of the students’ initial conceptual understanding, even when the completion of high school physics was accounted for. Other demographic characteristics, such as students’ mother tongue and country of birth, seem not to matter. Students’ initial conceptual understanding was the strongest predictor of students’ course learning outcomes, which makes understanding students’ initial differences particularly important. Since learning outcomes in introductory science courses often impact students’ later success in undergraduate science degree programs, these results suggest that the impact of completing high school physics may extend far beyond the first year. The persistence of initial gender differences in students’ learning outcomes remains an ongoing concern.
COMPARATIVE ANALYSIS OF SEA LEGAL REQUIREMENTS AND INSTITUTIONAL STRUCTURE IN CHINA (MAINLAND), CANADA AND THE UK (ENGLAND)
Authors: ZHOU KAI-YI , SHEATE WILLIAM R.
Published: January 2010

After the Law of the People's Republic of China on Environmental Impact Assessment (the EIA Law) came into effect in China (mainland) in September 2003, and notably in 2006, the Chinese government released a series of laws and regulations to strengthen strategic environmental assessment (SEA) application in China. SEA is acknowledged by the Chinese central government as a tool to help achieve sustainable development, and it is employed as an instrument to emphasise environmental protection and "scientific outlook of development" during the course of the current rapid industrial and urban development, to build a "harmonious society", and ultimately to achieve sustainable development. This paper compares the Chinese (mainland) SEA system, its legal requirements, institutional structure and procedural framework with the UK and the Canadian systems, to provide a comprehensive overview of the current status of the institutional and governance arrangements of the Chinese SEA system. The conclusions point to some possible explanations for less than optimum implementation of SEA in China, and suggestions for ways to improve the Chinese SEA system in the future.
THE ECOLOGICAL IMPACT ASSESSMENT OF URBAN DEVELOPMENT POLICIES: A CASE STUDY OF JI'NAN CITY, CHINA
Authors: WANG SHUJUN , LI JENNIFER , WU DAQIAN , WANG RENQING , ZHANG KAI , LIU JIAN
Published: January 2010

Based on socio-economic development and population growth, rapid urbanisation is currently happening in China, leading to urban expansion and land use changes. This, in turn, affects biodiversity, habitats and ecosystem services. It is therefore important to identify and assess the impact of urban development policies (UDP) on ecosystems and their components at a policy level. Ji'nan City, the capital of Shandong Province in Northern China, has been taken as a case study for assessing the ecological impact of UDP. The study found that, influenced by the traditional economy-oriented development strategy, the former UDP of Ji'nan City was mainly focused on urban socio-economic growth by speeding up the construction of urban infrastructure facilities, expanding urban built-up areas as well as strengthening the development of resource- and pollution-intensive industry, which in turn has negatively influenced the ecosystem services. The promulgation of eco-environmentally friendly UDP would contribute to protect and maintain the ecosystems and their components. Finally, recommendations for informing the legislation of new environmentally friendly UDPs and furthering the implementation of ecological impact assessment (EcIA) in China are proposed.
Zircon age constraints on the provenance of Llandovery to Wenlock sandstones from the Midland Valley terrane of the Scottish Caledonides
Authors: Phillips E. R. , Smith R. A. , Stone P. , Pashley V. , Horstwood M.
Published: January 2010

Synopsis

Detrital zircon populations within the Llandovery to Wenlock sandstones of the southern Midland Valley of Scotland indicate that the recycled orogenic provenance for these sedimentary rocks was essentially bimodal, comprising a younger Lower Palaeozoic component and an older predominantly Mesoproterozoic component. The Lower Palaeozoic contribution is dominated by Arenig/Llanvirn (
c
. 475 Ma) zircons interpreted as having been derived from a volcanic-plutonic source located within the Midland Valley terrane. The dominant Mesoproterozoic component within the sandstones is
c
. 1000 Ma and is thought to represent detritus shed from a Grenvillian (
c
. 1000–1800Ma) basement to the Midland Valley terrane. The scarcity of Archaean zircons precludes the Grampian metamorphic terrane Dalradian Supergroup as a supplier of sediment to the Ordovician–Silurian basins located along the southern margin of the Midland Valley. The age profiles of detrital zircon populations do not fit with a simple model of unroofing of a volcanic-arc complex. Rather they point to the periodic uplift of fault-bound, dismembered blocks of volcanic and plutonic rocks during a prolonged (Llandovery through to at least early Devonian) period of sinistral strike-slip deformation, and it was this which controlled basin development, sedimentary facies distribution and deformation along the southern side of the Midland Valley terrane.

Appendices 1 & 2 can be found at
http://www.geolsoc.org.uk/SUP18370
The age of the lower part of the New Red Sandstone of South-West Scotland
Authors: Mykura W.
Published: January 2010

Synopsis

The discovery of plants of Westphalian D age in a thin bed of sediment near the base of the ‘Permian’ Volcanic Group of Ayrshire has thrown doubt on the Permian age of the New Red Sandstone rocks throughout south-west Scotland. A review of the available evidence suggests that the greater part of the New Red Sandstone lavas and sediments of Ayrshire, Sanquhar and Thornhill and probably also part of the ‘Permian’ rocks of Arran may be Carboniferous. It seems likely that the base of the New Red Sandstone in the Southern Uplands is diachronous, and the basal beds in the Solway Basin and in North-West England may be considerably younger than the New Red Sandstone of Ayrshire.

The kylitic and teschenitic dolerite sills which cut the Carboniferous sediments of Ayrshire, and the intrusive monchiquites, which are closely associated with the ‘Permian’ volcanic necks of south-west Ayrshire, are now taken to be of Upper Coal Measures age.
The life attitude of the Silurian Trilobite
Phacops musheni
Salter 1864
Authors: Clarkson E. N. K.
Published: January 2010

Synopsis

Perfectly preserved material has been used in a study of the original life attitude of
Phacops musheni
Salter 1864, a Silurian phacopid trilobite. Data from previous functional studies are employed in elucidating the natural orientation of the cephalon; in lateral aspect this is the attitude in which the eye and the strip-like visual field are aligned horizontally. In this orientation the antero-lateral border rises towards the front and forms an ‘anterior arch’.

The relationship of the thoracic segments and the pygidium to the whole exoskeleton is worked out with respect to the orientated cephalon. Reference is made to accurately prepared illustrations of the outstretched trilobite, showing the various components of the exoskeleton as seen from the side in their true angular orientation.

Certain functional aspects of the extended exoskeleton are considered and it is suggested that this trilobite species led a vagrant benthonic existence.
The Mullach Sgar Complex, St Kilda, Outer Hebrides
Authors: Harding R. R.
Published: January 2010

Synopsis

The Mullach Sgar Complex crops out over one square mile on the islands of Hirta and Dun, St Kilda. It consists of dolerite, microdiorite, microgranite and blocks of ultrabasic rock, eucrite and gabbro. There were at least four phases of intrusion: in the first phase microgranite and microdiorite were intruded; in the second, microgranite and dolerite; in the third, microgranite and olivine dolerite; and in the fourth, microgranite and microdiorite. The more basic rocks occur as fragments in microgranite; some of the fragments have fine-grained margins with textures which suggest that basic magma chilled against acid magma. The attitudes of the microgranite sheets and of the zones of fragments round the margin of the Complex indicate that it developed by ring fracture and central subsidence.
The basic intrusive rocks of Caledonian age of the Haddo House and Arnage districts, Aberdeenshire
Authors: Gribble C. D.
Published: January 2010

Synopsis

Basic igneous rocks of the Haddo House and Arnage districts consist of olivine-norites, and quartz-norites which include uralitised and xenolithic types.

No layered sequence is observed in the basic igneous rocks of Haddo House and Arnage and their petrochemistry suggests that some water must have entered the magma in that area producing hypersthene- and quartz-normative rock types. This would account for the differences observed between the igneous rocks of Haddo and Arnage and those in other parts of north-east Scotland which were intruded at the same time, and might be products of the same parental magma.
Glacial stages and radiocarbon dates in Scotland
Authors: Sissons J. B.
Published: January 2010

Synopsis

New radiocarbon dates and previously published ones related to Scottish glacial events are discussed. Dormer’s conclusion that the Loch Lomond and Menteith end-moraine complexes were produced at the limit of the Zone III Readvance is confirmed. It is suggested that the Perth Readvance maximum occurred between 13 500 and 13 000 years ago, that the Aberdeen-Lammermuir Readvance post-dates a long interstadial, that an ice-movement during which shelly drift was deposited near Berwick pre-dates it, and that during the interstadial the British Isles were largely or entirely free of ice.
Geochronological studies on the Torridonian sediments of north-west Scotland
Authors: Moorbath S. , Stewart A. D. , Lawson D. E. , Williams G. E.
Published: January 2010

Synopsis

K-Ar and/or Rb-Sr measurements on detrital felspars, micas and on pebbles of acid porphyry and micaceous metasediment from the Torridonian succession yield rather well-defined groups of ages in the range
c.
1700–1150 million years. The Torridonian sediments were derived from a geologically and geochronologically complex source area, probably to the west, in which a gneissic basement complex was overlain by a now vanished 1800–1500 million year-old (Laxfordian?) supracrustal series which contained metasediments and acid igneous rocks. Rocks affected by an isotopic event about 1150–1100 million years ago also contributed detrital material. A further minimum age of
c.
1150 million years is reported for the Lewisian basement rocks of the Torridon area.

Total-rock Rb-Sr measurements on three Upper and two Lower Torridonian shales with rather high Rb/Sr ratios strongly suggest that the Torridonian sediments were deposited less than about 850–800 million years ago. Comparisons with the scanty published geochronological data do not prove or disprove the widely accepted Torridonian-Moine equivalence, but rule out any possible time correlation between the Torridonian sediments and the Gardar sediments of south-west Greenland, the Lower and Middle Keweenawan sediments of Canada and the Jotnian sediments of Scandinavia.
Tectonics in Upper Strathspey, Inverness-shire
Authors: Smith T. E.
Published: January 2010

Synopsis

Major and minor structures in the Moinian and Dalradian rocks of the Monadhliath Mountains are described and the tectonic history of the area outlined. Early major structures, isoclinal recumbent folds with north-east trending axial planes, are refolded by Late asymmetric folds with north-east trending axial planes dipping steeply to the south-east. These episodes of folding are correlated with those described elsewhere in the Ballappel Foundation and the Iltay Dalradians.