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Full-Text Articles in Engineering

Evaluation Of Bridge Abutment Capacity And Stiffness During Earthquakes, Rakesh K. Goel, Anil K. Chopra Feb 1997

Evaluation Of Bridge Abutment Capacity And Stiffness During Earthquakes, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

The “actual” capacity and stiffness values of the abutment‐soil systems at the US 101/Painter Street Overpass, determined from its earthquake motions, are used to investigate how abutment stiffness varies during earthquakes and to evaluate current modeling procedures. It is found that the “actual” abutment stiffness may be significantly different during different phases of the shaking and decreases significantly as the abutment deformation increases. The CALTRANS modeling procedure leads to a good estimate of the transverse abutment stiffness and capacity. However, this procedure may overestimate the normal abutment stiffness and capacity by a factor of over two, indicating that the assumed …


Simulating The Distribution Of Axon Size In Nerves, Robert B. Szlavik, Hubert De Bruin Jan 1997

Simulating The Distribution Of Axon Size In Nerves, Robert B. Szlavik, Hubert De Bruin

Biomedical Engineering

The electrical excitation threshold of a nerve axon is dependent upon the physical properties of the axon membrane as well as the axon diameter. Histological studies have confirmed that peripheral afferent muscle nerves have a characteristic distribution of axon diameters. We approximate a probability density function for this distribution that consists of the summation of several Gaussian functions. A transformation technique is then applied for the random generation of the nerve axon diameters from uniformly distributed random numbers. For the example presented, the resultant distribution of peripheral afferent muscle nerve axon diameters conforms approximately to the characteristic distribution that has …


Characteristic Of A Broadband Ti:Linbo3, Optical Modulator With Buried Electrodes And Etched Grooves In The Buffer Layer, Jinyang Hu, Boyu Wu, Xiaomin Jin Jan 1997

Characteristic Of A Broadband Ti:Linbo3, Optical Modulator With Buried Electrodes And Etched Grooves In The Buffer Layer, Jinyang Hu, Boyu Wu, Xiaomin Jin

Electrical Engineering

Traveling wave Ti:LiNbO3 Mach-Zehnder optical modulators with buried electrodes and etched grooves in the SiO2 buffer layer are analyzed by the finite element method. The tradeoff between the bandwidth BW and the half-wave voltage Vπ is discussed. The value of BW/Vπ is used to weight the total performance of the modulator. Taking a thick buffer layer and etching deep grooves in the buffer layer are demonstrated as two effective methods to improve the performance of the modulator. A 3-dB optical bandwidth of 18 GHz with half-wave voltage 5V at a wavelength of 1.55 pm could be obtained …


Effect Of Length On Compressive Strain Softening Of Concrete, Daniel C. Jansen, Surendra P. Shah Jan 1997

Effect Of Length On Compressive Strain Softening Of Concrete, Daniel C. Jansen, Surendra P. Shah

Civil and Environmental Engineering

The concept of localization during the postpeak of compressive strain softening is presented. To explore localization in compression, a feedback-control method using a linear combination of displacement and force that partially subtracts the elastic response of the specimen to give a stable feedback signal is used. Results are presented from two test series (45 and 90 MPa) that use this method to test cylinders with length-to-diameter ratios ranging from 2.0 to 5.5. It is shown that compression failure is in fact a localized phenomenon. The compressive fracture energy is divided into energy dissipated in the prepeak and the postpeak portions …


Assessment Of Cased-Borehole Seals Using An Ultrasonic Method, Nazli Yesiller, Craig H. Benson, Tuncer B. Edil, James Klima Jan 1997

Assessment Of Cased-Borehole Seals Using An Ultrasonic Method, Nazli Yesiller, Craig H. Benson, Tuncer B. Edil, James Klima

Civil and Environmental Engineering

Tests were conducted in Wisconsin from 1994 through 1996 in several boreholes using an ultrasonic method that was developed at the University of Wisconsin-Madison to assess the integrity of annular seals. Initially, three model boreholes simulating monitoring wells were installed to evaluate the effectiveness of the ultrasonic method. Different types of seals were placed around the casings and defects were purposely introduced in the seals to test the ultrasonic method. The ultrasonic method was effective for detecting the presence of different types of seals and defects and also the changes in the condition of seals with time. Then tests were …