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Articles 1 - 6 of 6
Full-Text Articles in Engineering
Flip-Chip (Fc) And Fine-Pitch-Ball-Grid-Array (Fpbga) Underfills For Application In Aerospace Electronics—Brief Review, Ephraim Suhir, Reza Ghaffarian
Flip-Chip (Fc) And Fine-Pitch-Ball-Grid-Array (Fpbga) Underfills For Application In Aerospace Electronics—Brief Review, Ephraim Suhir, Reza Ghaffarian
Mechanical and Materials Engineering Faculty Publications and Presentations
In this review, some major aspects of the current underfill technologies for flip-chip (FC) and fine-pitch-ball-grid-array (FPBGA), including chip-size packaging (CSP), are addressed, with an emphasis on applications, such as aerospace electronics, for which high reliability level is imperative. The following aspects of the FC and FPGGA technologies are considered: attributes of the FC and FPBGA structures and technologies; underfill-induced stresses; the roles of the glass transition temperature (Tg) of the underfill materials; some major attributes of the lead-free solder systems with underfill; reliability-related issues; thermal fatigue of the underfilled solder joints; warpage-related issues; attributes of accelerated life …
Space-Angle Signal Processing Using A Modulated Scatter Array, Nasr Alkhafaji
Space-Angle Signal Processing Using A Modulated Scatter Array, Nasr Alkhafaji
Electrical and Computer Engineering PhD Day
A UHF signal processing technique is described in the Fourier Space-Angle domain that uses an array of scattering elements with reflection coefficients modulated at baseband. The illumination arrival angle distributes a UHF phase across the array, and the baseband modulator phase at each of the array elements determines the radiation angle of the desired scattered product. Undesired products are re-radiated in different directions. Example 1, 2 and 4 element arrays operate at 432 MHz array with 700 Hz modulation. 2 element arrays cancel one sideband, and the 4 element array cancels both the undesired sideband and 2nd order products. Reflection …
Drafting In Self-Timed Circuits, Christopher Cowan
Drafting In Self-Timed Circuits, Christopher Cowan
Electrical and Computer Engineering PhD Day
Intervals between data items propagating in self-timed circuits are controlled by handshake signals rather than by a clock. The sequence of handshakes can be abstracted as the movement of “tokens”. In many self-timed designs, a trailing token will catch up with a leading token, even when it trails by thousands of gate delays. Simulations in SPICE of a simple GasP circular FIFO reveal this effect. Contrary to earlier work, we find the cause of drafting to be charge stored on an isolated node between two series transistors. This mechanism occurs in many decision gates that implement a logical AND. The …
Coaxial Magnetic Gearbox With A Flux Concentration Halbach Rotor And Consequent Pole Rotor Typology, Ho Yin Wong
Coaxial Magnetic Gearbox With A Flux Concentration Halbach Rotor And Consequent Pole Rotor Typology, Ho Yin Wong
Electrical and Computer Engineering PhD Day
This paper presents the performance comparison between a flux concentration and triple permanent magnet consequent pole magnetic gear rotor typology with the same 7.5:1 gear ratio. The triple permanent magnet consequent pole magnetic gear is unique in that it can create torque change through two field heterodyning pole combinations. The performance with respect to volumetric and mass torque density is considered. It is shown that the flux concentration typology can operate with a higher mass and volumetric higher torque density, even when using a low flux concentration ratio rotor.
Magnetically Geared Lead Screw, Mojtaba Bahrami Kouhshahi
Magnetically Geared Lead Screw, Mojtaba Bahrami Kouhshahi
Electrical and Computer Engineering PhD Day
New magnetically geared lead screw (MGLS) is proposed in this work, which relies only on magnetic loading. Therefore it can provide speed and force conversion like its mechanical counterparts, but unlike the mechanical gears, a MGLS contact-less operation enables it to operate without lubrication and it can operate with low noise, and higher efficiency. Its reliance on magnetic loading also provides overload protection. MGLS combines the concepts of two previously proposed actuators named linear magnetic gear (LMG) and magnetic lead screw (MLS). However, unlike the LMG and MLS the translator on a MGLS does not contain magnets and therefore for …
From A Locally Competitive Algorithm To Sensory Relevance Models, Walter Woods
From A Locally Competitive Algorithm To Sensory Relevance Models, Walter Woods
Electrical and Computer Engineering PhD Day
This poster addresses the development of a new Machine Learning (ML) mechanism, the Sensory Relevance Model (SRM), as a means of splitting information processing tasks into two sub-tasks with more intuitive properties. Specifically, SRMs are a front-end for other ML techniques, re-mapping the input data to a similar space with significantly more sparsity, achieved through the transformation and suppression of inputs irrelevant to the task. Prior work has attempted to reveal this information for Neural Networks (NNs) either as a post-processing step via saliency maps or through a simple masking of the input achieved with a dot product (so-called ``attention'' …