Influences of general computer experience and age on library database search performance

Two experiments examined the effects of general computer experience and age on library system search performance among novice library system users. Twenty younger adults (10 with high and 10 with low computer experience) and 20 older adults (10 with low and 10 with no computer experience) performed 10 search tasks of varying difficulty. Search success, syntax errors, database field specifications, keyword specifications, and use of Boolean operators were examined. Among younger novices, high computer experience was associated with slightly better performance than low computer experience. Among older novices, having some computer experience was associated with much better performance than no computer experience. Older computer users showed lower overall success rates, made more syntax and field specification errors, and demonstrated poorer understanding of Boolean logic and keyword matching algorithms than younger adults with similar computer experience. Implications for interface design and training interventions for novice on-line library system users are discussed.     

A Birefringent and Transparent Electrical Conductor

We have developed a range of thin film coatings that are transparent in the visible, electrically conducting, adjustably birefringent and capable of aligning calamitic liquid crystals. The coatings were fabricated from indium tin oxide by oblique or glancing angle deposition, and a wide range of microstructures such as helices, chevrons, uniaxial posts and biaxial slabs were produced. Under many deposition conditions, these structures showed optical transmittance and electrical conductivity comparable to standard indium tin oxide, yet a strong form birefringence (Δn > 0.07 at 589 nm) was also measured. In addition, many coatings were found to be capable of aligning liquid crystals along a common director, leading us to conclude that the technology may be useful in liquid crystal displays and other lightwave applications.     

A Cochlear-Implant Processor for Encoding Music and Lowering Stimulation Power

Cochlear implants (CIs), or bionic ears, restore hearing in profoundly deaf (greater than -90 dB hearing loss) patients. They function by transforming frequency patterns in sound into corresponding spatial electrode-stimulation patterns for the auditory nerve. Over the past 20 years, improvements in sound-processing strategies, in the number of electrodes and channels, and in the rate of stimulation have yielded improved sentence and word recognition scores in patients. Next- generation implants will be fully implanted inside the patient's body. Consequently, power consumption requirements for signal processing will be very stringent.     

Optical properties of porous helical thin films

Porous dielectric thin films, composed of isolated helical columns, are fabricated by the glancing angle deposition technique. The selective reflection of circularly polarized light and the optical rotation of linearly polarized light are investigated as a function of film material and helical morphology. The strongest chiral optical response is observed for titanium-dioxide films because of its large refractive index. Optical rotatory powers as high as 4.5 degrees are observed in 830-nm-thick helical films. By tailoring the pitch of the helical columns, the wavelength dependence of the circular reflection band is tuned to preferentially reflect red, green, or blue light, a promising quality for display applications.     

Fabrication and optical characterization of template-constructed thin films with chiral nanostructure

We report the fabrication of thin films perforated by high aspect ratio helical or chevron pores by an extension of the glancing angle deposition (GLAD) technique. The perforated films were created by transferring the nanostructure of a GLAD template film into target materials such as polymers and spin-on-glasses and subsequently removing the template. The pore shapes are shown to be highly controllable and films designed to suit particular applications are discussed. By a double templating technique, we replicate the structure of the original film using alternate materials, which are typically less suited to the unmodified GLAD technique. Helical films of Cu and Ni were created by this method and the process should be transferable to additional electrodeposited materials. The optical rotatory power of perforated thin films formed on glass substrates was characterized and perforated films were shown to be effective in rotating the polarization plane of linearly polarized incident light by as much as 1.4/spl deg///spl mu/m.     

A four-phase handshaking asynchronous static RAM design forself-timed systems

The motivation of designing asynchronous memory arises from the recent development of asynchronous processors. As different from the conventional design, the proposed asynchronous static RAM can: (1) communicate with other asynchronous systems based on a four-phase handshaking control protocol; and (2) generate the read/write completion signals with increased average speed by the variable bit-line load concept. The techniques investigated include (1) dual-rail voltage sensing completion detection for read operation and (2) multiple delays completion generation for write operation. In this paper, the performances of these techniques are evaluated for 1 Mb memory with four regions of bit-line segmentation. The simulated and measured results are presented and compared     

New filters for internal model control design

In this paper we study the design of a new two-degree-of-freedom filter for the internal model control (IMC) method. The new filter alleviates some disadvantages of the standard IMC filter when the IMC method is applied to unstable plants that do not have non-minimum-phase zeros. We show that by employing the new filter, the resulting system has a flatter frequency response, better stability robustness, and little overshoot in the step response. Furthermore, one of its design parameters can be related directly to the closed-loop bandwidth and the other parameter can be used to control the recovery time after an overshoot has occurred in the step response. These features are important in the application of the IMC method to a new approach of adaptive robust control. Examples are given in the paper to illustrate the new filter design.