The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform

Juha Kostamovaara - One of the best experts on this subject based on the ideXlab platform.

  • lateral current confinement determines silicon avalanche transistor operation in short pulsing mode
    IEEE Transactions on Electron Devices, 2008
    Co-Authors: Guoyong Duan, Sergey N Vainshtein, Juha Kostamovaara
    Abstract:

    The transient in a Si bipolar junction transistor was investigated in high-current short-pulsing ( 2 ns) mode both experimentally and numerically. A comparison of measured and simulated waveforms clearly showed that only a small fraction of the perimeter of the emitter-Base Interface (in the lateral direction) takes part in the switching transient when a capacitor of relatively small value (80 pF) is discharged across the transistor to obtain a current pulse of a few nanoseconds in duration. A good agreement was found between measurements and simulations in the 2-D numerical model when the effective operating perimeter was used as a parameter in the model. The results allowed reliable analyses of the thermal regime to be performed. Possible reasons for the significant current confinement in short-pulsing mode and relatively homogeneous transistor switching with longer current pulses are discussed, and a mechanism of fast lateral turn-on spread is assumed. One conclusion of practical importance is that a short-pulsing relatively high-current mode could not be realized without current confinement in the lateral direction.

Guillermo Avila - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Drying and Soil-Base Interface on the Behavior of an Expansive Soil Mixture
    Geotechnical and Geological Engineering, 2020
    Co-Authors: Jumanah Hajjat, Duaa Al-jeznawi, Marcelo Sánchez, Guillermo Avila
    Abstract:

    Expansive soils exhibit complex behavior associated with significant volume changes triggered by moisture variations induced by changes in environmental conditions. This type of process impacts on soil properties, such as shear strength, stiffness, and permeability. Also, cracks generally develop upon desiccation. There are still several gaps in the current knowledge in this area, particularly in relation to the factors that affect the shear strength of soils and control the formation of drying cracks. This paper focuses on the impact of some of these factors on crack formation and shear strength of an expansive soil mixture made up of 75% kaolin and 25% bentonite, % by mass. Three factors were considered in this research; soil structures (associated with different sample preparation methods), initial saturation, and textures at soil-Base Interface. Two laboratory series consisting of desiccation plate and soil-Base Interface shear tests were conducted. For each series, three types of soil specimens were prepared considering different preparation methods (with the associated different soil structures) and initial saturation conditions namely; slurries, fully-saturated compacted and unsaturated compacted specimens. Soil-Base Interface shear strengths were determined using four different Interface textures; grooves oriented perpendicular to shear direction, spiral (circular) indentations, grooves aligned parallel to the shear direction, and smooth surface. For the desiccation plate tests, two types of textures were adopted for the plate-Base, namely, circular indentations and smooth to study constrained and free shrinkage conditions, respectively. Results of desiccation tests revealed that cracks developed in the constrained plate (e.g., with circular indentations), whereas no cracks were observed under free displacements conditions (e.g., smooth surface). The direct shear tests revealed that the soil-Base Interface shear strength is strongly affected by the specimen moisture, soil structure and the direction of the shearing  respect to the grooves orientation. For the three set of experiments conducted (i.e., slurry, compacted-saturated, compacted-unsaturated), the highest strength was found for the surface with groove oriented perpendicular to shear direction and the lowest one for the smooth plate. The shear strength associated with the circular-grooves Base is in-between those ones observed for the plate with grooves oriented perpendicular and parallel to the shear direction.

Robert L. Lytton - One of the best experts on this subject based on the ideXlab platform.

Shilpa Shetty - One of the best experts on this subject based on the ideXlab platform.

  • Integrity of the Interface Between Denture Base and Soft Liner: A Scanning Electron Microscopic Study
    The Journal of Indian Prosthodontic Society, 2012
    Co-Authors: G. Muralidhar, C. L. Satish Babu, Shilpa Shetty
    Abstract:

    Aims and objectives of the study was to study the integrity of the Interface between the denture Base and the soft liner when the thickness of the soft liner was 0.5, 1.0 and 2.0 mm, and to study the integrity of the soft liner and denture Base Interface as influenced by aging process. 80 rectangular Based specimens were fabricated using heat cured acrylic resin. The heat cured component of the specimen was fabricated from stainless steel template form by compression molding technique. Different thickness of silicone soft layer component was added to heat cured acrylic resin component of the specimen following the manufacturer’s instructions to fabricate the group A, group B, group C and group D specimens. All the specimens were subjected to the same finishing and polishing procedures. The group A specimens was immediately scanned in scanning electron microscope after processing. A thermo statically controlled artificial saliva bath designed to maintain the temperature between 38 ± 4°C was used to simulate the oral condition and to age the group B, group C and group D specimens for 3 months after which they were subjected to scanning under a scanning electron microscope. All the aged specimens demonstrated two types of failures namely adhesive which occurred along the bond Interface between the soft liner and the acrylic resin and adhesive and cohesive type of failure which occurred not only at the Interface but also within the soft liner material itself. When the data was subjected to ANOVA, the group A specimens showed statistical significance with group B ( P  = 0.006), group C ( P  = 0.007) and group D specimens ( P  = 0.004), the level of significance being ( P  

  • integrity of the Interface between denture Base and soft liner a scanning electron microscopic study
    The Journal of Indian Prosthodontic Society, 2012
    Co-Authors: G. Muralidhar, C Satish L Babu, Shilpa Shetty
    Abstract:

    Aims and objectives of the study was to study the integrity of the Interface between the denture Base and the soft liner when the thickness of the soft liner was 0.5, 1.0 and 2.0 mm, and to study the integrity of the soft liner and denture Base Interface as influenced by aging process. 80 rectangular Based specimens were fabricated using heat cured acrylic resin. The heat cured component of the specimen was fabricated from stainless steel template form by compression molding technique. Different thickness of silicone soft layer component was added to heat cured acrylic resin component of the specimen following the manufacturer’s instructions to fabricate the group A, group B, group C and group D specimens. All the specimens were subjected to the same finishing and polishing procedures. The group A specimens was immediately scanned in scanning electron microscope after processing. A thermo statically controlled artificial saliva bath designed to maintain the temperature between 38 ± 4°C was used to simulate the oral condition and to age the group B, group C and group D specimens for 3 months after which they were subjected to scanning under a scanning electron microscope. All the aged specimens demonstrated two types of failures namely adhesive which occurred along the bond Interface between the soft liner and the acrylic resin and adhesive and cohesive type of failure which occurred not only at the Interface but also within the soft liner material itself. When the data was subjected to ANOVA, the group A specimens showed statistical significance with group B (P = 0.006), group C (P = 0.007) and group D specimens (P = 0.004), the level of significance being (P < 0.05). However, there was no statistical significance between group B and C (P = 0.98), group C and D specimens (P = 0.52), group B and D specimens (P = 0.70), the level of significance being (P < 0.05). Based on the results, statistical analysis of the results and within the limitations of this in vitro study the following conclusions can be drawn: The thickness of the liner did not show a statistically significant rate of failure on the integrity of the Interface between the denture Base resin and the soft liner and aging conditions simulating the clinical environment showed a statistically significant rate of failure on the integrity of the Interface between the denture Base resin and the soft liner.

Guoyong Duan - One of the best experts on this subject based on the ideXlab platform.

  • lateral current confinement determines silicon avalanche transistor operation in short pulsing mode
    IEEE Transactions on Electron Devices, 2008
    Co-Authors: Guoyong Duan, Sergey N Vainshtein, Juha Kostamovaara
    Abstract:

    The transient in a Si bipolar junction transistor was investigated in high-current short-pulsing ( 2 ns) mode both experimentally and numerically. A comparison of measured and simulated waveforms clearly showed that only a small fraction of the perimeter of the emitter-Base Interface (in the lateral direction) takes part in the switching transient when a capacitor of relatively small value (80 pF) is discharged across the transistor to obtain a current pulse of a few nanoseconds in duration. A good agreement was found between measurements and simulations in the 2-D numerical model when the effective operating perimeter was used as a parameter in the model. The results allowed reliable analyses of the thermal regime to be performed. Possible reasons for the significant current confinement in short-pulsing mode and relatively homogeneous transistor switching with longer current pulses are discussed, and a mechanism of fast lateral turn-on spread is assumed. One conclusion of practical importance is that a short-pulsing relatively high-current mode could not be realized without current confinement in the lateral direction.