Soft Error Rate Reduction Using Circuit Optimization and Transient Filter Insertion

This paper describes a tunable transient filter (TTF) design for soft error rate reduction in combinational logic circuits. TTFs can be inserted into combinational circuits to suppress propagated single-event transients (SETs) before they can be captured in latches or flip-flops. TTFs are tuned by adjusting the maximum width of the propagated SET that can be suppressed. A TTF requires 6–14 transistors, making it an attractive cost-effective option to reduce the soft error rate in combinational circuits. A global optimization approach based on geometric programming that integrates TTF insertion with dual-V _DD and gate sizing is described. Simulation results for the 65 nm process technology indicate that a 17–48× reduction in the soft error rate can be achieved with this approach.     

Reliable Lead-Free Rework Process for Stacked CSP Components

Memory module manufacturers face an ongoing challenge to incorporate more functionality and superior performance with each new generation of product offering. The growth in demand for memory capacity is surpassing the pace at which memory component manufacturers are able to cost-effectively produce the next generation of monolithic memory devices. This drives the need for utilizing stacked components for memory module assemblies. The complex nature of stacked chip-scale package (CSP) components coupled with a lead-free process presents unique rework challenges that needed to be studied and addressed. Reworking a CSP is complicated as the solder joints are hidden underneath the component. The process window available for the lead-free rework process is very narrow. There are number of other critical factors, which complicate and affect the repeatability of the rework process. The complications only increase with the use of stacked CSP devices. The rework of package stacked CSP components, which are complex in nature, is a daunting task. The key issues and observations with regard to the issues and challenges associated with the lead-free rework of mirror-imaged package stacked CSP components has been presented in this paper. In addition, the paper also provides a recipe for reliably reworking these packages.     

PAR2-Induced Tissue Factor Synthesis by Primary Cultures of Human Kidney Tubular Epithelial Cells Is Modified by Glucose Availability

Coagulopathies common to patients with diabetes and chronic kidney disease (CKD) are not fully understood. Fibrin deposits in the kidney suggest the local presence of clotting factors including tissue factor (TF). In this study, we investigated the effect of glucose availability on the synthesis of TF by cultured human kidney tubular epithelial cells (HTECs) in response to activation of protease-activated receptor 2 (PAR2). PAR2 activation by peptide 2f-LIGRLO-NH₂ (2F, 2 µM) enhanced the synthesis and secretion of active TF (~45 kDa) which was blocked by a PAR2 antagonist (I-191). Treatment with 2F also significantly increased the consumption of glucose from the cell medium and lactate secretion. Culturing HTECs in 25 mM glucose enhanced TF synthesis and secretion over 5 mM glucose, while addition of 5 mM 2-deoxyglucose (2DOG) significantly decreased TF synthesis and reduced its molecular weight (~40 kDa). Blocking glycosylation with tunicamycin also reduced 2F-induced TF synthesis while reducing its molecular weight (~36 kDa). In conclusion, PAR2-induced TF synthesis in HTECs is enhanced by culture in high concentrations of glucose and suppressed by inhibiting either PAR2 activation (I-191), glycolysis (2DOG) or glycosylation (tunicamycin). These results may help explain how elevated concentrations of glucose promote clotting abnormities in diabetic kidney disease. The application of PAR2 antagonists to treat CKD should be investigated further.     

Towards impedance-based temperature estimation for Li-ion battery packs

In order to meet the required power and energy demand of battery-powered applications, battery packs are constructed from a multitude of battery cells. For safety and control purposes, an accurate estimate of the temperature of each battery cell is of vital importance. Using electrochemical impedance spectroscopy (EIS), the battery temperature can be inferred from the impedance. However, performing EIS measurements simultaneously at the same frequency on each cell in a battery pack introduces crosstalk interference in surrounding cells, which may cause EIS measurements in battery packs to be inaccurate. Also, currents flowing through the pack interfere with impedance measurements on the cell level. In this paper, we propose, analyse, and validate a method for estimating the battery temperature in a battery pack in the presence of these disturbances. First, we extend an existing and effective estimation framework for impedance-based temperature estimation towards estimating the temperature of each cell in a pack in the presence of crosstalk and (dis)charge currents. Second, the proposed method is analysed and validated on a two-cell battery pack, which is the first step towards development of this method for a full-size battery pack. Monte Carlo simulations are used to find suitable measurement settings that yield small estimation errors and it is demonstrated experimentally that, over a range of temperatures, the method yields an accuracy of ±1°C in terms of bias, in the presence of both disturbances.     

Scuffing resistance of salt bath nitrocarburized medium carbon steel

The usefulness of the ferritic nitrocarburizing treatment for improving the tribological properties of ferrous components is well established. However, the thin compound layer of beneficial epsilon carbonitride that develops at the surface lacks the ability to bear high Hertzian stresses. Nitrocarburizing in the austenite phase field of the Fe---N---C system overcomes this disadvantage since the formation of a hard zone of martensite-bainite below the compound layer provides the back-up to withstand point loads. Results of the Falex scuffing test indicate that the failure load increases on account of the thicker compound layer at the surface. The results indicate further that the frictional heat generated during the test coupled with working by the jaws convert the retained austenite present in the sub-compound layer to harder microconstituents. The study suggests that the austenitic treatment could be useful for applications involving simultaneous heat and work such as hot working dies.     

Wear of steel in rolling contact with silicon nitride

Wear of steel (AISI M-50 and AISI 52100) bearing balls in lubricated rolling contact with ground and ground-and-lapped silicon nitride rods was studied using a ball-on-rod rolling-contact-fatigue (RCF) tester. The steel balls suffered significant wear in rolling contact with the as-ground (R_a = 0.18 μm) silicon nitride rods. The wear volume loss was approximately linear with the rolling distance. The wear rate increased linearly with the initial Hertzian contact stress in the range, 3–6.5 GPa. Examination of the wear tracks in a scanning electron microscope revealed surface features that suggested a wear mechanism that involved plastic deformation of the steel surface, squeezing of the metal symmetrically outward and rupture of the metal layers at the edges. The steel balls suffered negligible wear but failed by spalling in rolling contact with the ground-and-lapped silicon nitride rods (R_a = 0.08 μm) at an initial contact stress of 5.5 GPa. The as-ground silicon nitride rods exhibited neither wear nor spalling in the RCF tests, while the ground-and-lapped silicon nitride rods showed no wear but occasional spalling failure.     

RECDWELL-Computer aided design of six-link planar dwell mechanisms

Linkage-type dwell mechanisms are less expensive to manufacture and maintain, and can be superior to cams at high speed. They are also easily adjustable for satisfying variable output motion requirements. In spite of these advantages they have not found wide application. Part of the reason for this lack of popularity is the absence of proper design tools. The inspiration for this work stems from the need to bridge this technological gap. RECDWELL helps to design both circular-arc and straight-line dwell mechanisms using a technique which is simple, efficient and accurate.     

Design, implementation, and characterization of an optical power supply spot-array generator for a four-stage free-space optical backplane

The design and implementation of a robust, scalable, and modular optical power supply spot-array generator for a modulator-based free-space optical backplane demonstrator is presented. Four arrays of 8 x 4 spots with 6.47-mum radii (at 1/e(2) points) pitched at 125 mum in the vertical direction and 250 mum in the horizontal were required to provide the light for the optical interconnect. Tight system tolerances demanded careful optical design, robust optomechanics, and effective alignment techniques. Issues such as spot-array generation, polarization, power efficiency, and power uniformity are discussed. Characterization results are presented.     

Probabilistic prediction of minimum fatigue life behaviour in α + β titanium alloys

The objective of this work was to develop and demonstrate a probabilistic life prediction method for the prediction of minimum fatigue lives that are typically used in the design of fracture critical rotating turbine engine components. A Monte Carlo analysis was used to predict the variability in fatigue lives based on the distribution of microstructural features that lead to early crack initiation as well as the variability in small fatigue crack growth rates. Two titanium alloys, both with bimodal microstructures, were tested and analysed in this study. The distribution of critical microstructural features was calibrated based on test results and understanding of microstructure neighbourhood effects. Testing was conducted on both alloys and included both smooth and notched specimens. The predictions are presented and compared with the data for smooth and notch geometries for the various loading conditions. A parametric study was performed to identify the importance of several model inputs and to identify areas for future improvement.