bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoelectric Micro-Cooler for Hot-Spot Thermal Management
Authors: Wang Peng , Bar-Cohen Avram , Yang Bao , Solbrekken Gary L. , Zhang Yan , Shakouri Ali
Published: April 2009

Driven by shrinking feature sizes, microprocessor “hot-spots” — with their associated high heat flux and sharp temperature gradients — have emerged as the primary “driver” for on-chip thermal management of today’s IC technology. Solid state thermoelectric micro-coolers offer great promise for reducing the severity of on-chip “hot-spots”, but the theoretical cooling potential of these devices, fabricated on the back of the silicon die in an IC package, has yet to be determined. The results of a three-dimensional electro-thermal finite-element modeling study of such a micro-cooler are presented. Attention is focused on the hot-spot temperature reductions associated with variations in micro-cooler geometry, chip thickness, and chip doping concentration, along with the parasitic Joule heating effects from the electrical contact resistance and current flow through the silicon. The modeling results help to define the optimum solid-state cooling configuration and reveal that, for the conditions examined, nearly 80% of the hot-spot temperature rise of 2.5°C can be removed from a 70μm × 70μm, 680W/cm2 hot-spot on a 50μm thick silicon die with a single micro-cooler.
High Resolution Characterization of Materials Used in Packages Through Digital Image Correlation
Authors: Srinivasan V. , Radhakrishnan S. , Zhang X. , Subbarayan G. , Baughn T. , Nguyen L.
Published: April 2009

In this study, we demonstrate a simple, full field displacement characterization technique based on digital image correlation (DIC). We develop a robust correlation measure implemented in a code and use it to characterize materials at high spatial and displacement resolution. We describe the methods implemented in the DIC code and compare against those available in the literature. We show how sample preparation may be entirely eliminated by using the natural speckle inherent in specular (rough) surfaces. We demonstrate further that the use of natural speckle enables very high spatial resolution (100 microns or less) since creating artificial speckle patterns in miscroscale spatial regions is a significant challenge. The software is also designed to be robust to varying contrasts between the deformed and the undeformed images. Its accuracy is enhanced by using NURBS (Non-Uniform Rational B-Spline) as the interpolating function in the code. We demonstrate the developed software and the underlying procedure on several packaging problems of interest. We measure the CTE of Alumina (Al2O3) using its natural speckle, we calculate the strain and therefore the modulus during mechanical testing of composite materials and we characterize the time dependent behavior of a micro-fiber reinforced composite (RT/Duroid) at high temperature.
Use of Psychoacoustic Metrics for the Analysis of Next Generation Computer Graphic Card Noise
Authors: Novak Colin , Ule Helen , Gaspar Robert , Refai-Ahmed Gamal
Published: April 2009

The continuing challenge to deliver performance improvements in computer graphic cards has long since progressed to the point of requiring finned, passive, cooling devices to dissipate the heat generated by the graphics processing unit (GPU). The heat flux generated by further improvements now exceeds that dissipation capacity so that passive cooling can no longer provide adequate cooling the GPU. The dissipation rates required by the latest generation of designs can be delivered by forced air cooling of finned heat sinks. The concurrent challenge to the industry is to provide this cooling while minimizing the noise generated by these cooling fans. A significant aspect associate with this problem is missed if one only considers the problem to be a one-dimensional sound level issue. From a consumer’s perspective, the perceived quality of the noise emitted takes precedence over what traditional acoustical analysis techniques of this fan noise may imply. Here, psychoacoustic or sound quality metrics, may be a more applicable analysis tool as it provides the quantification of these qualitative human impressions. The present study investigates the validity of using several psychoacoustic metrics for the analysis of fan cooled computer graphics card noise. Using experimentally measured fan noise from three different cooling fan designs, a sound quality analysis was performed using loudness, sharpness, roughness, fluctuation strength, prominent tone and articulation index. A discussion and comparison of measured results using traditional analysis techniques is also included. It was found that some of the metrics proved more useful than others as an analysis tool for this specific noise source. A discussion of the applicability of the various sound quality metrics along with justifications is presented.
Experimental Study on the Double-Sided Air Cooling for Integrated Power Electronics Modules
Authors: Pang Ying Feng , Scott Elaine P. , Liang Zhenxian , van Wyk J. D.
Published: April 2009

The objective of this work is to quantify the advantages of using double-sided cooling as the thermal management approach for the integrated power electronics modules. To study the potential advantage of the Embedded Power packaging method for the double-sided cooling, experiments were conducted. Three different cases were studied. To eliminate the effect of the heat sink on either side of the module, no heat sink was used in all three cases. The thermal tests were conducted such that the integrated power electronics modules were placed in the middle of flowing air in an insulated wind tunnel. Modules without additional top DBC, with additional top DBC, and with additional top DBC as well as heat spreaders on both sides were tested under the same condition. A common parameter, junction-to-ambient thermal resistance, was used to compare the thermal performance of these three cases. Despite the shortcoming of this parameter in describing the three-dimensional heat flow within the integrated power electronics modules, the concept of the thermal resistance is still worthwhile for evaluating various cooling methods for the module. The results show that increasing the top surface area can help in transferring the heat from the heat source to the ambient through the top side of the module. Consequently, the ability to handle higher power loss can also be increased. In summary, the Embedded Power technology provides an opportunity for implementing double-sided cooling as thermal management approach compared to modules with wire-bonded interconnects for the multichips.
Distributed Leakage Flow in Raised-Floor Data Centers
Authors: Radmehr Amir , Schmidt Roger R. , Karki Kailash C. , Patankar Suhas V.
Published: April 2009

In raised-floor data centers, distributed leakage flow—the airflow through seams between panels on the raised floor—reduces the amount of cooling air available at the inlets of the computer equipment. This airflow must be known to determine the total cooling air requirement in a data center. The amount of distributed leakage flow depends on the area of the seams and the plenum pressure, which, in turn, depends on the amount of airflow into the plenum and the total open area (combined area of perforated tiles, cutouts, and seams between panels) on the raised floor. The goal of this study is to outline a procedure to measure leakage flow, to provide data on the amount of the distributed leakage flow, and to show the quantitative relationship between the leakage flow and the leakage area. It also uses a computational model to calculate the distributed leakage flow, the flow through perforated tiles, and the plenum pressure. The results obtained from the model are verified using the measurements. Such a model can be used for design and maintenance of data centers. The measurements show that the leakage flow in a typical data center is between 5–15% of the available cooling air. The measured quantities were used to estimate the area of the seams; for this data center, it was found to be 0.35% of the floor area. The computational model represents the actual physical scenarios very well. The discrepancy between the calculated and measured values of leakage flow, flow through perforated tiles, and plenum pressure is less than 10%.
Flat Miniature Heat Pipe With Composite Fibre Wick Structure for Cooling of Mobile Handheld Devices
Authors: Singh Randeep , Akbarzadeh Aliakbar , Mochizuki Mastaka , Saito Yuji , Nguyen Thang , Kao Bob , Sataphan Tanaphan , Takenaka Eiji , Wuttijumnong Vijit
Published: April 2009

Heat pipe is a very reliable and efficient two phase heat transfer device that has been extensively investigated for applications in electronic cooling. In the past, different types of heat pipe have been developed for specific as well as general applications. With the development in technology and trend towards miniaturization, thermal control of electronic devices with compact structure and concentrated heat sources has really become a challenge. Miniature heat pipes can be considered as potential candidates to address these issues. In the present paper, experimental investigation of the Flat Miniature Heat Pipe (FMHP), with the characteristic thickness of 1.5 mm and new type of composite fibre wick structure (FB-G), has been done for the thermal management of the mobile handheld devices. The so called composite fibre structure consists of combination of copper fibres and axial grooves as a capillary wick along the inner wall of the heat pipe. The design configuration of the experimental FMHP comprised of L-shaped flat heat pipe with rectangular cross section (1.5 mm × 8 mm) and heat transfer length of 100 mm. The body of FMHP was made of copper with pure deionised water as the working fluid. FMHP was easily able to transfer required heat fluxes in the range of 1–6 W/cm2 given by mobile-handheld chipset. Thermal resistance of the heat pipe from evaporator to the condenser surface came out to be in the range of 0.25–0.45 °C/W. In order to highlight the performance of the FMHP with composite fibre wick, thermal resistance was compared to different prototypes with screen mesh and axial grooves. It can be concluded from the outcomes of the investigation that the composite fibre wick structure provides an optimum capillary head and permeability for better heat transfer capabilities and minimal end to end temperature gradient than the conventional type of wick structures. FMHPs with composite fibre wicks will find prospective applications in the cooling of the compact handheld devices like Palm PC, mobile phones and digital diaries.
Neural-Genetic Optimization of Temperature Control in a Continuous Flow Polymerase Chain Reaction Microdevice
Authors: Lee Hing Wah , Arunasalam Parthiban , Azid Ishak A. , Seetharamu Kankanhally N.
Published: April 2009

In this study, a hybridized neural-genetic optimization methodology realized by embedding finite element analysis (FEA) trained artificial neural networks (ANN) into genetic algorithms (GA) is used to optimize temperature control in a ceramic based continuous flow polymerase chain reaction (CPCR) device. The CPCR device requires three thermally isolated zones of 94°C, 65°C and 72°C for the corresponding process of denaturing, annealing and extension to complete a cycle of polymerase chain reaction. Three separately addressable heaters provide heat input to each zone, microfluidic channels allow for the transport of fluid between zones and thermal isolation between the zones is maintained by machining air-gaps into the device. The most important aspect of temperature control in the CPCR is to maintain temperature distribution at each reaction zone with a precision of ±1°C or better irrespective of changing ambient conditions. Results obtained from the FEA simulation are compared with published experimental work. Simulation results show good comparison with experimental work for the temperature control in each reaction zone of the microfluidic channels. The data is then used to train the ANN to predict the temperature distribution of the microfluidic channel for new heater input power and fluid flow rate. Using these data, optimization of temperature control in the CPCR device is achieved by embedding the trained ANN results as a fitness function into GA. The objective of the optimization is to minimize the temperature difference in each reaction zone of the microfluidic channel while satisfying the residence time requirement. Finally, the optimized results for the CPCR device are used to build a new FEA model for numerical simulation analysis. The simulation results for the neural-genetic optimized CPCR model and the initial CPCR model are then compared. The neural-genetic optimized model shows a significant improvement from the initial model establishing the optimization methods superiority.
Novel Test Methods for Die Strength
Authors: Tsai M. Y. , Chen C. H. , Lin C. S.
Published: April 2009

Recently, the 3-D or stacked-die packages are increasingly popular for packaging ICs into a system or subsystem to satisfy the needs of low cost, small form factor, and high performance. For the applications of these packages, IC wafers have to be ground to be relatively thin through the wafers thinning processes (such as grinding, polishing, and plasma etching). The strength of dies has to be determined for the design requirement and thus assuring reliability of the packages. From the published data, there still exist some issues including a large scatter existed in die strength data, and difficulties with differentiating the causes of the low strength from the grinding or die sawing either by three-point bending or four-point bending test. The purposes of this study is to develop new, reliable and simple test methods for determination of die strength to improve the data scatter and also provide a solution for differentiating the factors that affect the variability of die strength, in order to find out the causes of the weakness of the die strength. In this study, two new test methods, point-loaded circular plate with simple supports test (PLT-I) and point-loaded plate on elastic foundation test (PLT-II) are proposed and evaluated by testing two groups of silicon dies with different surface conditions. The surface conditions (roughness) of the specimens are determined by atomic force microscopy and correlated to failure strength. The failure forces from both tests have to be modified by using maximum stress obtained from theory or finite element analysis to get the failure strength. The test results are compared with each other and further with widely-used four-point bending test. The results suggest that, unlike the four-point bending test, both methods provide very consistent data with a small scatter for these two groups of specimens, and indicated the die strength is highly dependent on the surface roughness. Accordingly, these two methods can provide not only a (bi-axial) stress field similar to temperature-loaded die in the packages, but also simple, feasible, reliable and chipping-free tests for silicon dies of dummy or real IC chips, without strict geometrical limitation, such as beam-type geometry for three-point or four-point bending test.
Design and Analysis of a Comb-Drive Actuator for Large Displacement
Authors: Ku C. L. , Chen R. , Chen Y. C.
Published: April 2009

Comb-drive electrostatic actuators have been widely applied to steer a gripper, an acceleratometer, a scanning mirror, and a xy-stage because their output forces are easily controlled and capacitively sensed. To obtain large displacement with low drive voltage, a comb-drive actuator has to be designed with narrower gap and larger overlapping area between two electrodes. As a result, it will induce the instability or side sticking during operation; that is, the stationary and the moving electrodes will stick together and the actuator fails to operate. Furthermore, due to the asymmetric electrodes caused by inevitably imperfect fabrication of the actuator, the comb-drive actuator may be unstable for a large displacement, resulting from the unbalanced electrostatic forces between two electrodes. We report a novel design, which utilizes a set of extra electrode structure to compensate the unbalanced electrostatic forces. Simulation results demonstrated that the larger displacement is achieved while the size of the comb-drive actuator keeps the same. For better performance, the design of electrode structure and the number of electrodes are discussed in this report.
Development of Lead-Free Compatible Molded Underfill (MUF) Materials for Flip Chip Stacked Packaging: Key Challenges and Learnings
Authors: LeBonheur Vassou , Chee Choong Kooi
Published: April 2009

This paper reports the structure-properties-performance relationship of various molded underfill materials for potential applications in flip-chip MMAP (FCMMAP) and mixed technology (FC and WB) stacked CSP (MTsCSP) packages. Chemical, rheological, and thermo-mechanical properties of five high temperature reflow compatible materials were characterized and relationship to materials processability & package reliability performance were investigated. Materials having higher filler concentration and lower coefficient of thermal expansion tended to exhibit improved HTR compatibility due to improved moisture resistance and decreased CTE mis-match.
Thermal Interface Material Technology Advancements and Challenges: An Overview
Authors: Dani Ashay , Matayabas James C. , Koning Paul
Published: April 2009

With an increase in the number of transistors (higher power), shrinking processor size (smaller die), and increasing clock speeds (higher frequency) for next generation microprocessors, heat dissipation at the silicon die level has become a critical focus area for microprocessor architecture and design. In addition, power removal at low cost continues to remain the key challenge as we develop the next generation packaging technologies. Novel Thermal Interface Materials (TIM) are required to be designed and developed to meet these new package thermal targets. This paper presents an overview of the novel TIM technologies developed at Intel including greases, phase change materials (PCM), gels, polymer solder hybrids, and solder TIM for multiple generations of desktop, server and mobile microprocessors. The advantages and limitations of these TIM technologies in the thermal management of flip chip packaging are reviewed for Intel’s microprocessors.
Numerical Modeling of Jet Impingement and Validation of Convection: Conduction Decoupling in Thermal Design
Authors: Iyengar Madhusudan , Ellsworth Michael J. , Simons Robert E. , Campbell Levi A.
Published: April 2009

The steady rise in cooling requirements of commercial computer products mandates the development of aggressive thermal management techniques, as well as accurate design and analysis methodologies. Single phase direct liquid jet impingement, offers a controlled high performance alternative, by eliminating the need for a thermal interface, and by delivering the coolant directly to the surface of the chip. This paper characterizes the thermal performance of a specific direct liquid jet impingement scheme in which the hot fluid exhausts via return vents located in the immediate vicinity of the jet. The study also quantifies the error associated with using the average heat transfer coefficient as a thermal performance metric for the non-uniform cooling boundary condition that occurs in such jet impingement solutions. The thermal performance of the direct liquid jet impingement designs are characterized and studied, via CFD (Computational Fluid Dynamics) models constructed using a commercial numerical solver. The hydraulic performance is analytically estimated using a simple loss coefficient based model. A square 10×10×0.75 mm3 chip, dissipating 400W, and cooled by water at 32°C, is considered as the representative example for the analysis. The effect of jet density on thermal performance is characterized for 1–400 jets/cm2, and for several feasible flow parameters, i.e. inlet jet velocities (5–10 m/s) and volumetric flow rates (946–1893 liters/minute). For the configurations explored, the optimal jet density was found to be 100 jets/cm2. An engineering cut-off point for the use of the 1-D average heat transfer coefficient metric, was identified as 10 jets/cm2. The error associated with use of a 1-D average heat transfer coefficient was shown to be in excess of 5% when the jet density is less than 10 jets/cm2, as high as 20% for the single jet case, and less than 0.7% for jet densities greater than 36 jets/cm2.
Heat Spreading Analysis of a Heat Sink Base Embedded With a Heat Pipe
Authors: Borgmeyer Brian V. , Ma H. B.
Published: April 2009

A simplified theoretical model predicting the heat transfer performance of a heat sink base embedded with a flat heat pipe is developed. Numerical analysis was performed using the commercial software FLUENT. The investigation indicates that for heat sink bases embedded with a typical heat pipe, the entire heat sink can be modeled as a flat plate with a uniform temperature and an effective convection heat transfer coefficient. The prediction is compared with the experimental data obtained previously.
Design of Transducer and Package at the Same Time
Authors: Li Gary , McNeil Andrew , Koury Dan , Chapman Mike , Monk Dave
Published: April 2009

The early effort of MEMS sensor development was focused mainly on the transducer: designing and manufacturing a mechanical device that could convert a physical input into an electrical signal using traditional semiconductor processes. With the rapid advancement in MEMS technologies, MEMS packaging is becoming increasingly critical and plays a major role in the successful commercialization of a MEMS product. Freescale has adopted the philosophy [1–2] of concurrent transducer and package designs to facilitate the rapid introduction of sensor products into the market. This paper presents a sub-modeling procedure that allows the modeling and simulation of a transducer and a package seamless at the same time.
Wafer Level Micropackaging for RF MEMS Switches
Authors: Forehand David I. , Goldsmith Charles L.
Published: April 2009

Wafer-level micro-encapsulation is an innovative, low-cost, wafer-level packaging method for encapsulating RF MEMS switches. This zero-level packaging technique has demonstrated 0.04 dB package added insertion loss at 35 GHz. This article overviews the processes, measurements, and testing methods used for determining the integrity and performance of individual encapsulated RF MEMS packages.
Theta_JC Metrology Development: Fixture Design Modeling
Authors: Dizon Michael Butch M. , Prstic Suzana , Moon Sung-Won
Published: April 2009

The junction-to-case thermal resistance or Theta_JC is one of the important metrics used to evaluate the performance and reliability of a particular electronic package. Currently, there is no established JEDEC standard for a Theta_JC test fixture. This paper presents the results of computational fluid dynamic (CFD) modeling studies carried out to propose a simple and robust Theta_JC fixture. The theoretical Theta_JC value for a particular package was first obtained assuming idealized conditions. The model was then modified to incorporate actual fixture conditions. The objective is to design a tester fixture that reduces the Theta_JC measurement error, i.e. ideal vs. fixture. The effect of various design parameters on the measured Theta_JC value was investigated. Sensitivity studies included cavity or insulation configuration, cold plate size, thermocouple probe orientation, thermal interface materials, and applied power. Modeling results showed that, regardless of the insulation design, there was considerable heat loss through the test board on which the package was mounted. This resulted in a lower Theta_JC value measured, with errors up to 30%. To reduce the heat loss and measurement error, a heater was mounted at the bottom of the board and maintained at a temperature within 1 to 2°C of the junction temperature. Using this simple approach, the measurement error was reduced to around 6%. From the results of the study, an optimized prototype fixture design is proposed.
Constitutive Modeling of Lead-Free Solders
Authors: Pei M. , Qu J.
Published: April 2009

Solders are used extensively as electrical interconnects in microelectronics packaging. Because of environmental concerns, lead-based solders are being replaced by Sn/Ag and Sn/Ag/Cu based solder materials. Since the thermomechanical reliability of modern electronic devices depends on, to a large extent, the fatigue and creep behavior of the solder joints, it is imperative to understand the deformation behavior of these new lead-free solders. This study conducted extensive thermomechanical testing on several commercial lead-free solder alloys. Anand viscoplastic model was used to describe the behavior of these materials with new curve fitting techniques. A modified Anand models was proposed that can yield a more accurate description of lead-free solders.
The Impact of Varying Feature Dimensions on Substrate Reliability Risks
Authors: Helms Kayleen L. E. , Zhou Qing A. , Zhang Charles
Published: April 2009

A sensitivity study is undertaken to characterize the impact of varying feature dimensions in emerging electronic packaging technologies. Specifically, the overall structural performance of the substrate under use conditions (thermal and combined thermomechanical loading) is investigated. The study consists of both modeling and experimental efforts. Modeling approaches are employed within the framework of a finite element code to simulate performance of different design geometry combinations in the known failure mode of solder resist layer cracking. In the models, two levels of complexity are used to better identify the impact of the individual features on the overall substrate reliability. First, local geometry is captured by including each substrate layer. Individual component geometries like microvias and PTHS are also explicitly modeled to capture synergistic failures modes. Second, more realistic non-linear material properties are used to characterize time, temperature, and rate-dependant constitutive behavior of individual substrate materials such as buildup, core, metal, etc. In the experiments, substrate warpage and reliability data is collected for validating the predictive modeling capability. From this study, directions for future design guidelines varying feature dimensions while maintaining substrate reliability are proposed.
Boiling of Enhanced Surfaces at High Heat Fluxes in a Small Boiler
Authors: Chien Liang-Han , Chen C.-W.
Published: April 2009

High operating heat fluxes and small boiling space are the two major challenges to apply boiling heat transfer in electronics cooling. This experimental study seeks to find a good boiling performance surface that is suitable for cooling a CPU dissipating up to 88 W through a 14 mm × 14 mm surface area in a 15 mm × 54mm × 54mm vessel. Three structured boiling surfaces and three porous surfaces were tested in water at 60°C pool temperature. The experimental data showed that the best cross-grooved surface and the best porous surface have similar boiling performance curves. The evaporation resistances of these two surfaces vary from 0.12 to 0.26 K/W. The minimum evaporation resistance of the best cross-grooved surface was 0.125 K/W at 86.5 W. Because the evaporator area is much smaller than the condenser or the heat sink area, the thermal resistance is dominated by the evaporator. The condensation resistance of the 54mm × 54mm condensing area varies from 0.01 to 0.022 K/W, which is much smaller than the evaporation resistance of every boiling surface in the present test.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.
Reliability Challenges in Design and Operation of High Heat Powered Processors
Authors: Heydari Ali , Gektin Vadim
Published: April 2009

Advances in processor design have been made possible in part by increases in the packaging density of electronics. At the same time, combination of increased power dissipation and packaging density has led to substantial growth in the chip and system heat fluxes and amplified complexity in electrical signal integrity and mechanical stack-up design in the recent years, particularly, in the high-end computers. With the trend towards miniaturization, heat removal, along with increased reliability requirements, has become a major bottleneck in product development, especially, in low profile systems, telecom servers and blades. Cooling of high heat flux components may require consideration of innovative open-loop, as well as plausible closed-loop, cooling designs for data centers. This paper addresses reliability aspects of thermal, electrical, mechanical, and interconnect design and long-life operation of high-end air-cooling, as well as feasible active open and closed-loop cooling technologies of high heat flux processors.
A systematic review of correct bicycle helmet use: how varying definitions and study quality influence the results
Authors: Lee R S , Hagel B E , Karkhaneh M , Rowe B H
Published: April 2009

Background:

Bicycle helmets effectively reduce the risk of bicycle-related head injuries and trauma; however, they must fit properly to be effective. Little is known about the prevalence of correctly worn helmets and factors associated with proper helmet use.

Objective:

To examine proper bicycle helmet use through a systematic review.

Methods:

Comprehensive searches of electronic medical databases were performed, and completed by grey literature and reference list checks to identify eligible studies. Studies eligible for inclusion had to involve cyclists and report on the prevalence of correct or incorrect helmet use. Two reviewers independently selected studies and data were extracted regarding the prevalence and factors influencing proper helmet wearing of cyclists.

Results:

An inclusive search strategy led to 2285 prescreened citations; 11 of the studies were finally included in the review. Overall, correct helmet use varied from 46% to 100%, depending on the criteria used by researchers to define proper helmet use; stricter criteria reduced the proportion of properly worn helmets. Adulthood, female sex and educational interventions were associated with correct helmet use in some studies. Self-reported poor helmet fit (OR = 1.96; 95% CI 1.10 to 3.75), posterior positioning of helmet (OR = 1.52; 95% CI 1.02 to 2.26) and helmet loss in crash (OR = 3.25; 95% CI 1.82 to 5.75) increased the risk of head injury. In addition, educational programmes on helmet use in schools increased correct helmet use among schoolchildren.

Conclusions:

This systematic review outlines the current state of the literature including the variability in research methodology and definitions used to study proper helmet-wearing behaviour among cyclists.
The first integrated use of in situ U–Pb geochronology and geochemical analyses to determine long-distance transport of glacial erratics from mainland Canada into the western Arctic Archipelago
Authors: Doornbos Chris , Heaman Larry M. , Doupé Jonathan P. , England John , Simonetti Antonio , Lajeunesse Patrick
Published: April 2009

Glacial erratics collected on Melville Island, western Canadian Arctic Archipelago, were analyzed to determine their mainland provenance, thereby constraining their long-distance transport by the Laurentide Ice Sheet. These erratics can be broadly subdivided into three main lithologies: granite (n = 15), quartzite (n = 7), and diabase–diorite (n = 3). The granite erratics are most distinctive from a provenance perspective and can be further subdivided into three geochemical groups based on their potassium content: (1) a high-K2O group (K2O > 4.0 wt.%), (2) an intermediate-K2O group (K2O between 2.0 and 4.0 wt.%), and (3) a low-K2O group (K2O < 2.0 wt.%). In situ thin section laser ablation inductively coupled plasma mass spectrometer U–Pb zircon ages obtained for eight granite erratics yielded both Archean (2575 Ma) and a range of Paleoproterozoic (2472–1778 Ma) crystallization ages. In addition, three overprint ages were identified at 1.90, 1.84, and ∼1.0 Ga. The most compelling constraint for a northward regional ice flow originating on the mainland are two high-precision conventional U–Pb zircon ages of 1969.5 ± 1.0 and 2472.3 ± 0.5 Ma, indicating that these granite erratics must have been derived from the 2.0–1.9 Ga Taltson–Thelon Orogen and the nearby 2.5–2.4 Ga Queen Maud Block, respectively. These granite-dominated terranes are located 600 km due south and southeast of the collection area on Melville Island. Although it is unknown whether the final deposition of these erratics on Melville Island involved transport by one or more glaciations, it is apparent that this ice flow cannot be accommodated by the proposed north–south axis of the M’Clintock Ice Divide, the primary topographic feature of the northwestern Laurentide Ice Sheet during the last glacial maximum. The transport of erratics reported here would have required a former ice divide oriented east–west over the mainland, close to that proposed for the Ancestral Keewatin Divide. An east–west ice divide in this region is consistent with previously reported ice-flow indicators that document northward flow from the mainland and recent thermomechanically coupled ice-sheet numerical modeling that indicates former maximum ice thickness on the mainland immediately south of Melville Island.
Deep electrical structure of northern Alberta (Canada): implications for diamond exploration
Authors: Türkoğlu Erşan , Unsworth Martyn , Pana Dinu
Published: April 2009

Geophysical studies of upper mantle structure can provide constraints on diamond formation. Teleseismic and magnetotelluric data can be used in diamond exploration by mapping the depth of the lithosphere–asthenosphere boundary. Studies in the central Slave Craton and at Fort-à-la-Corne have detected conductors in the lithospheric mantle close to, or beneath, diamondiferous kimberlites. Graphite can potentially explain the enhanced conductivity and may imply the presence of diamonds at greater depth. Petrologic arguments suggest that the shallow lithospheric mantle may be too oxidized to contain graphite. Other diamond-bearing regions show no upper mantle conductor suggesting that the correlation with diamondiferous kimberlites is not universal. The Buffalo Head Hills in Alberta host diamondiferous kimberlites in a Proterozoic terrane and may have formed in a subduction zone setting. Long period magnetotelluric data were used to investigate the upper mantle resistivity structure of this region. Magnetotelluric (MT) data were recorded at 23 locations on a north–south profile extending from Fort Vermilion to Utikuma Lake and an east–west profile at 57.2°N. The data were combined with Lithoprobe MT data and inverted to produce a three-dimensional (3-D) resistivity model with the asthenosphere at 180–220 km depth. This model did not contain an upper mantle conductor beneath the Buffalo Head Hills kimberlites. The 3-D inversion exhibited an eastward dipping conductor in the crust beneath the Kiskatinaw terrane that could represent the fossil subduction zone that supplied the carbon for diamond formation. The low resistivity at crustal depths in this structure is likely due to graphite derived from subducted organic material.
Effect of surface heterogeneity steps-terraces in a mean field model for the catalytic CO-NO reaction
Authors: Cortés Joaquín , Valencia Eliana
Published: April 2009

Based on a model proposed by Olsson et al. (Surf. Sci. 2003, 529, 338), a study is made through a mean field scheme of the effect of steps-terraces superficial heterogeneity, whose energy differences have been determined recently by means of density functional theory (DFT), in the catalytic reduction reaction of NO by CO over palladium. Several aspects are seen, such as the relation between the activities produced in both sectors of the surface as a function of temperature and the energy difference between them, the activity and coverage versus the temperature and the gas phase concentration curves, and the effect on these variables of the activation energy values on the steps of some stages of the kinetic mechanism. The system shows a reaction order with respect to CO and NO that changes sign between low and high temperatures, from negative to positive in the case of CO and the opposite for NO.
Reversible decomposition of mono(α-hydroxy)phosphines and their reaction with α,β-unsaturated aldehydes
Authors: Moiseev Dmitry V. , Marcazzan Paolo , James Brian R.
Published: April 2009

The mono(α-hydroxy)phosphines R2PCH(OH)R′ (R = Ph, R′ = H, Et, CH2Ph, Ph, p-X-C6H4; R = cyclohexyl, R′ = Ph) are prepared under solvent-free conditions by a 1:1 reaction of Ph2PH with the appropriate aldehyde, and their stabilities (with respect to reversible dissociation into reactants), studied in DMSO, Et2O, and MeOH, increase with decreased basicity of the hydroxyphosphine; for example, for the Ph2PCH(OH)C6H4-p-X phosphines, stability decreases in the order: X = CN > Cl > F > H > Me > OMe. A 1:1 room-temperature reaction of the (α-hydroxy)phosphines (except for R′ = H) with cinnamaldehyde in DMSO slowly yields the known mono- and di-phosphines Ph2PCH(Ph)CH2CHO (4a) and Ph2PCH(Ph)CH2CH(PPh2)OH (10a), and the corresponding R′CHO aldehyde. In MeOH, the sequentially formed intermediates, PhCH=CHCH(OH)PPh2, PhCH(OH)CH=CHPPh2, and Ph2PCH(Ph)CH=CHOH, were detected en route to 4a and 10a. Reaction of cinnamaldehyde with Ph2PCH2OH gives 4a and the hemiacetal Ph2PCH2OCH2OH formed from the reactant hydroxyphosphine with the co-product formaldehyde. Reactions carried out in MeOH are faster because of the formation of hemiacetals from the phosphine-containing aldehyde products; thus, 4a is seen as Ph2PCH(Ph)CH2CH(OMe)(OH), which on dissolution in Et2O, reverts to the aldehyde. The reaction rates and equilibrium concentrations of the various species depend on the R′ group of the reactant phosphine; the rates of consumption of the hydroxyphosphines in the reactions with cinnamaldehyde decrease in the order: Ph2PCH(OH)Ph > Ph2PCH(OH)Et > Ph2PCH(OH)CH2Ph >> Ph2PCH2OH. The reactivity pattern of Ph2PCH(OH)Ph with sinapaldehyde [3,5-(OMe)2-4-OH-cinnamaldehyde] in DMSO follows that seen for cinnamaldehyde. Reaction of Ph2PH with cinnamaldehyde in DMSO affords 4a and 10a via the same intermediates seen with the Ph2PCH(OH)R′ reagents, but these latter reactions are thought to occur via direct attack on cinnamaldehyde by the hydroxyphosphine rather than via Ph2PH.
AN EFFICIENT OPTIMAL SOLUTION OF A TWO-CRANE SCHEDULING PROBLEM
Authors: ZHOU WEIHUA , WU XIAOBO
Published: April 2009

This paper studies a two-crane scheduling problem in a port terminal. These two cranes are deployed in a block of a port terminal. They can move along a bi-directional traveling lane and must maintain a safe distance between them to avoid collision. A group of export containers in a block is required to be transported by cranes from their storage location to an access point of the block. Each container is associated with a due date. The problem is to find a schedule such that all containers are carried to the access point before their due dates. If such schedule does not exist, then the problem becomes to find schedules to minimize the maximum tardiness, the number of tardy jobs, respectively. In this paper, we first identify the necessary and sufficient conditions for the existence of a feasible schedule, i.e., a schedule transports all containers to the access point before their due dates and does not violate the requirement to maintain a safe distance between two cranes. We prove that if there exists at least one feasible schedule, then there must be a permutation schedule with containers sequenced in earliest due date (EDD) order to be feasible. An efficient algorithm is developed to find a feasible schedule given its existence. Furthermore, we provide efficient algorithms for minimizing the maximum tardiness, the number of tardy jobs, the makespan and the total completion time, respectively.
GALACTIC ANGULAR MOMENTA AND ANGULAR MOMENTUM CORRELATIONS IN THE COSMOLOGICAL LARGE-SCALE STRUCTURE
Authors: SCHÄFER BJÖRN MALTE
Published: April 2009

I review the theory of angular momentum acquisition of galaxies by tidal torquing, the resulting angular momentum distribution and the angular momentum correlation function, and discuss the implications of angular momentum alignments for weak lensing measurements. Starting from linear models for tidal torquing, I summarize perturbative approaches and the results from n-body simulations of cosmic structure formation. Then I discuss the validity of decompositions of the tidal shear and inertia fields, the effects of angular momentum biasing, the applicability of parametrized angular momentum correlation models and the consequences of angular momentum correlations for shape alignments. I compile the results of observations of shape alignments in recent galaxy surveys as well as in n-body simulations. Finally, I review the contamination of weak lensing surveys by spin-induced shape alignments and methods for suppressing this contamination.
MULTIOBJECTIVE DESIGN OF EQUIVALENT ACCELERATED LIFE TESTING PLANS
Authors: LIAO HAITAO , LI ZHAOJUN
Published: April 2009

This paper is focused on the multiobjective design of equivalent accelerated life test (ALT) plans. Equivalent ALT plans are expected to achieve the same statistical performance as a baseline ALT plan yet lead to other desired performance measures such as reduced test time and total cost. Before determining the desired multiobjective equivalent ALT plans, an efficient fast non-dominated sorting genetic algorithm (NSGA-II) is utilized to identify a set of Pareto optimal solutions. To handle a large number of Pareto optimal solutions, a self-organizing map (SOM) and data envelopment analysis (DEA) are sequentially applied to classify the Pareto solutions and reduce the size of the suggested solution set. This integrated approach allows for the tradeoff of information among the Pareto solutions and the reduction in the size of the solution set. It provides a useful tool for practitioners to make meaningful decisions in planning ALT experiments.
DEVELOPMENT OF FUZZY SOFTWARE OPERATIONAL PROFILE
Authors: KUMAR KRISHNAMOORTHY SARAVANA , MISRA RAVINDRA BABU , GOYAL NEERAJ KUMAR
Published: April 2009

Software operational profile (SOP) has found its extensive use in applications such as estimation of software reliability, allocation of testing resources, evaluation of software quality attributes, performance analysis and testing of software. However, benefits of the SOP can only be reaped if it is developed during early stages of software life cycle and updated for changes in operational structure with the progress in development of software process. In the early stages of software life cycle usage data is available only in linguistic form. This linguistic data may be obtained from previous release of software usage data, marketing surveys, experts or user's opinion or from combinations of these. Moreover, due to limited data resources and large efforts required to convert the gathered data into point estimates, reluctance is observed towards the development of SOP in spite of its numerous benefits. This paper proposes a fuzzy software operational profile (FSOP) approach, which takes input data in the form of linguistic variables from experts and assigns occurrence possibilities to the input parameters. Linguistic data collected from the experts are processed to obtain the resultant fuzzy operational profile. Further, the resultant profile is defuzzified and normalized to estimate occurrence probability of operations. The proposed method has been applied to various software systems and results obtained are compared with existing practice. Besides simplicity, FSOP can easily be altered for changes in operational architecture and frequencies simply by changing the location and value of the affected linguistic variable.
UNCERTAINTY ASSESSMENT TECHNIQUES FOR SYSTEM AVAILABILITY
Authors: MIMAN MEHMET , POHL EDWARD A.
Published: April 2009

This paper provides an approach for assessing the uncertainty associated with the estimate of the availability of a two-state repairable system. During the design stage it is often necessary to allocate scarce testing resources among various components in an efficient manner. Although there are a variety of importance and uncertainty measures for the reliability of a system, there are limited measures for systems availability. This study attempts to fill the gaps on availability importance measures and provide insights for techniques to reduce the variance of a system-level availability estimate efficiently. The variance importance measure is constructed such that it provides a measure of the improvement in the variance of the system level availability estimate through the reduction of the variance of the various component availability estimates. In addition, a cost model is developed that trades-off cost and uncertainty. The measure is illustrated for five common system structures. Monte Carlo Simulation is used to illustrate the use of the assessment tools on a specific problem. Observations conclude that results are consistent with reliability importance measures.
COGBROKER — A COGNITIVE APPROACH TO INTELLIGENT PRODUCT BROKERING FOR E-COMMERCE
Authors: GUAN SHENG-UEI , TAN WEN PIN , LIU FEI
Published: April 2009

Researchers have proposed intelligent product-brokering applications to help facilitate the m-commerce shopping process. However, most algorithms require explicit, user-provided feedback to learn about user preference. In practical applications, users may not be motivated to provide unrewarded and time-consuming feedback. By adopting a cognitive approach, this paper investigates the possibility of replacing user feedback with user behavioral data analysis during product browsing. By means of evolutionary algorithms, the system is able to derive corresponding models that simulate the user's shopping behavior. User group profiling is also implemented to help identify the user's shopping patterns. Upon simulations of trial cases with consistent and rational shopping patterns, our experimental results confirm this approach being promising. The system shows high accuracy in detecting the preferences of the user. The algorithms are also portable and effective across different products.
DESIGNING RELEVANT FEATURES FOR CONTINUOUS DATA SETS USING ICA
Authors: PRASAD MITHUN , SOWMYA ARCOT , KOCH INGE
Published: April 2009

Isolating relevant information and reducing the dimensionality of the original data set are key areas of interest in pattern recognition and machine learning. In this paper, a novel approach to reducing dimensionality of the feature space by employing independent component analysis (ICA) is introduced. While ICA is primarily a feature extraction technique, it is used here as a feature selection/construction technique in a generic way. The new technique, called feature selection based on independent component analysis (FS_ICA), efficiently builds a reduced set of features without loss in accuracy and also has a fast incremental version. When used as a first step in supervised learning, FS_ICA outperforms comparable methods in efficiency without loss of classification accuracy. For large data sets as in medical image segmentation of high-resolution computer tomography images, FS_ICA reduces dimensionality of the data set substantially and results in efficient and accurate classification.