Strain Measurement in a Shape Memory Alloy with Strain Gauges

Abstract:  The recovery of shape due to temperature-induced martensite to austenite phase transformation in shape memory alloys (SMA), such as nickel titanium alloys, has been investigated and utilised in applications for many years. One of the problems in incorporating SMA in host materials, such as composites, is the poor bonding characteristics of the SMA. A closely related problem in experiments is the measurement of strains in SMA specimens; as thin wires have been used in many of the experimental investigations, strains have been deduced from length measurements. In the current work, electrical resistance strain gauges have been bonded on SMA strips. Tensile strains up to 8% during tensile loading as well as compressive strains during strain recovery due to subsequent heating have been measured. Strains determined by other methods, such as extensometer and length measurements, are also reported and compared. The major contribution of this work is the successful bonding of strain gauges on SMA and the measurement of large strains (up to 8%).     

Single-crystal growth of La2−2x Sr1+2x Mn2O7 under pressure

Large single crystals of La_2–2x Sr_1+2x Mn₂O₇ (x=0.3 to 0.525) have been prepared under controlled atmospheric conditions. The crystals were grown by the floating-zone technique in an image furnace under a mixed oxygen/argon atmosphere pressurized to 6–8×10⁵ Pa. Rectangular single crystals with sizes up to 50×9×4 mm³ have been obtained. The phase-purity, composition, and quality of the crystals were analyzed by X-ray diffraction and electron probe microanalysis. The magnetic behavior is found to be sensitive to the composition of the atmosphere during growth.     

Short pineapple-leaf-fiber-reinforced low-density polyethylene composites

Short pineapple-leaf-fiber-(PALF)-reinforced low-density polyethylene (LDPE) composites were prepared by melt-mixing and solution-mixing methods. In the melt-mixing technique, a mixing time of 6 min, rotor speed of 60 rpm, and mixing temperature of 130°C were found to be the optimum conditions. Tensile properties of melt-mixed and solution-mixed composites were compared. Solution-mixed composites showed better properties than melt-mixed composites. The influence of fiber length, fiber loading, and orientation on the mechanical properties has also been evaluated. Fiber breakage and damage during processing were analyzed from fiber distribution curve and optical and scanning electron micrographs. Considering the overall mechanical properties and processability characteristics, fiber lenght of 6 mm was found to be the optimum length of pineapple leaf fiber for the reinforcement in LDPE. The mechanical properties were found to be enhanced and elongation at break reduced with increasing fiber loading. Longitudinally oriented composites showed better properties than randomly and transversely oriented composites. Recyclability of the composite was found to be very good. A comparison of the properties of the PALF-reinforced LDPE composites with those of other cellulose-fiber-reinforced LDPE systems indicated superior performance of the PALF–LDPE composites.© 1995 John Wiley & Sons. Inc.     

Flexible Strategies for Disk Scheduling in Multimedia Presentation Servers

Multimedia presentations (e.g., lectures, digital libraries) normally include discrete media objects such as text and images along with continuous media objects such as video and audio. Objects composing a multimedia presentation need to be delivered based on the temporal relationships specified by the author(s). Hence, even discrete media objects (that do not normally have any real-time characteristics) have temporal constraints on their presentations. Composition of multimedia presentations may be light (without any accompanying video or large multimedia data) or heavy (accompanied by video for the entire presentation duration). The varying nature of the composition of multimedia presentations provides some flexibility for scheduling their retrieval. In this paper, we present a min-max skip round disk scheduling strategy that can admit multimedia presentations in a flexible manner depending on their composition. We also outline strategies for storage of multimedia presentations on an array of disks as well as on multi-zone recording disks.Emilda Sindhu received the B.Tech degree in Electrical & Electronics from University of Calicut, India, in 1995 and the M.S. degree in Computer Science in 2003 from National University of Singapore. This paper comprises part of her master thesis work. She is presently employed as Senior Research Officer at the A-star Institute of High Performance Computing (IHPC), Singapore. Her current research interests include distributed computing particulary Grid computing. She is involved in the development of tools and components for distributed computing applications.Lillykutty Jacob obtained her B.Sc (Engg.) degree in electronics and communication from the Kerala University, India, in 1983, M.Tech. degree in electrical engineering (communication) from the Indian Institute of Technology at Madras in 1985, and PhD degree in electrical communication engineering from the Indian Institute of Science, in 1993. She was with the department of computer science, Korea Advanced Institute of Science and Technology, S. Korea, during 1996–97, for post doctoral research, and with the department of Computer Science, National University of Singapore, during 1998–2003, as a visiting faculty. Since 1985 she has been with the National Institute of Technology at Calicut, India, where she is currently a professor. Her research interests include wireless networks, QoS issues, and performance analysis.Ovidiu Daescu received the B.S. in computer science and automation from the Technical Military Academy, Bucharest, Romania, in 1991, and the M.S. and Ph.D. degrees from the University of Notre Dame, in 1997 and 2000. He is currently an Assistant Professor in the Department of Computer Science, University of Texas at Dallas. His research interests are in algorithm design, computational geometry and geometric optimization.B. Prabhakaran is currently with the Department of Computer Science, University of Texas at Dallas. Dr. B. Prabhakaran has been working in the area of multimedia systems: multimedia databases, authoring & presentation, resource management, and scalable web-based multimedia presentation servers. He has published several research papers in prestigious conferences and journals in this area.Dr. Prabhakaran received the NSF CAREER Award FY 2003 for his proposal on Animation Databases. Dr. Prabhakaran has served as an Associate Chair of the ACM Multimedia2003 (November 2003, California), ACM MM 2000 (November 2000, Los Angeles), and ACM Multimedia99 conference (Florida, November 1999). He has served as guest-editor (special issue on Multimedia Authoring and Presentation) for ACM Multimedia Systems journal. He is also serving on the editorial board of Multimedia Tools and Applications journal, Kluwer Academic Publishers. He has also served as program committee member on several multimedia conferences and workshops. Dr. Prabhakaran has presented tutorials in several conferences on topics such as network resource management, adaptive multimedia presentations, and scalable multimedia servers.B. Prabhakaran has served as a visiting research faculty with the Department of Computer Science, University of Maryland, College Park. He also served as a faculty in the Department of Computer Science, National University of Singapore as well as in the Indian Institute of Technology, Madras, India.     

The Two-User Compound Interference Channel

We introduce the two-user finite state compound interference channel. The main contributions involve both novel inner and outer bounds. For the Gaussian case, we characterize its capacity region to within one bit. The inner bound is multilevel superposition coding but the decoding of the levels is opportunistic, depending on the channel state. The genie aided outer bound is motivated by the typical error events of the achievable scheme.     

A new direct coagulation casting process for alumina slurries prepared using poly(acrylate) dispersant

Direct coagulation casting (DCC) of concentrated aqueous alumina slurries prepared using ammonium poly(acrylate) dispersant has been studied using MgO as coagulating agent. Addition of small amounts of MgO increased the viscosity of the concentrated alumina slurries with time and finally transformed it in to a stiff gel. Sufficient working time for degassing and casting could be achieved by cooling the slurries to a temperature of ∼5 °C after proper homogenization after the addition of MgO. The DCC slip with alumina loading in the range of 50–55 vol% showed relatively low viscosity (0.12–0.36 Pa s at shear rate of 93 s⁻¹) and yield stress (1.96–10.56 Pa) values. The wet coagulated bodies prepared from slurries of alumina loading in the range of 50–55 vol% had enough compressive strength (45–211 kPa) for handling during mould removal and further drying. The coagulated bodies prepared from slurries of alumina loading in the range of 50–55 vol% showed linear shrinkage in the range of 4.8–2.3 during drying and 17.1–16.2 during sintering respectively. Near-net-shape alumina components with density >98% TD could be prepared by the DCC process.     

Nanoscale Membrane Strips for Benign Sensing of HgII Ions: A Route to Commercial Waste Treatments

The integration of actively‐functional receptors into nanoscale networks outperformed competent detection devices and other ion‐sensing designs. Synthesis of azo chromophores with long hydrophobic tails showed an ecofriendly sensing and an extreme selectivity for divalent mercury analytes. In order to tailor the tip to Hg^II ion‐sensing functionality, we manipulated the chromophores into nanoscale membrane discs, which led to small, easy‐to‐use optical sensor strips. The design of these hydrophobic probes into ordered pore‐based membranes transformed the ion‐sensing systems into smart, stable assemblies and portable laboratory assays. The nanosensor membrane strips with chemical and mechanical stability allowed for reversible, stable and reusable detectors without any structural damage, even under rigorous chemical treatment for several numbers of repeated cycles. The optical membrane strips provided Hg^II ion‐sensing recognition for both cost‐ and energy‐saving systems. Indeed, the synthetic strips proved to have an efficient ability for various analytical applications, targeting especially for on‐site and in situ chemical analyses, and for continuous monitoring of toxic Hg^II ions. On the proximity‐sensing front, these miniaturized nanomembrane strips can revolutionize the consumer and industrial market with the introduction of the probe surface‐mount naked‐eye ion‐sensor strips.     

Hand-Gesture Computing for the Hearing and Speech Impaired

An instrumented data glove with a wireless interface provides convenient and natural human-computer interaction for people with speech or hearing impairments.