Influence of nanoclay and coupling agent on the physical and mechanical properties of polypropylene/bagasse nanocomposite

In this work, the effects of nanoclay (1–4 wt %) and coupling agent (2 and 4 wt %) loading on the physical and mechanical properties of nanocomposites are investigated. Composites based on polypropylene (PP), bagasse flour, and nanoclay (montmorillonite type) was made by melt compounding and then compression molding. When 1–3 wt % nanoclay was added, the tensile properties increased significantly, but then decreased slightly as the nanoclay content increased to 4%. The impact strength was 6% lower by the addition of 1 wt % nanoclay, it was decreased further when the nanoclay content increased from 1 to 4%. Finally, the water absorption of PP/bagasse composites was lowered with the increase in nanoclay content. Additionally, the coupling agent, 4 wt % MAPP, improved the mechanical and physical properties of the composites more than the 2 wt % MAPP. From these results, we can conclude that addition of nanoclay enables to achieve better physical and mechanical properties in conventional composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical and thermal properties of polypropylene/recycled polyethylene terephthalate/chopped rice husk composites

The various ratios of recycled polyethylene terephthalate (rPET) into polypropylene (PP) filled with 40 parts chopped rice husk per hundred part of polymer have been studied. Composites were prepared using a corotating twin screw extruder at temperature zones of 165–215, well below 250°C (rPET mp temperature) and characterized by mechanical and thermal properties. To improve the compatibility between different components, PP grafted with maleic anhydride was added as a coupling agent in all the compositions studied. The results showed that the addition of rPET improved the tensile and flexural modulus and impact strength of the composite while reducing its tensile and flexural strength. The scanning electron microscopy micrographs of samples in the injection direction showed that some particle shaped rPET inside the composites appear as drawn fibrils and some appear as plates. Differential scanning calorimetric studies showed that the addition of rPET particles to the composites decrease the PP crystallization temperatures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Monitoring the effects of impact damages on modal parameters in carbon fiber entangled sandwich beams

The aim is to study the impact toughness of two types of entangled sandwich materials (heavy and light) with the help of vibration testing. A simple case of symmetrical impacts is studied in this article as no literature is available regarding impact tests on entangled sandwich materials. The variation of modal parameters with two levels of damage (BVID and Damage not apparent on the surface) is studied. Vibration test results show that the light entangled specimens possessing good damping capabilities seem more sensitive to impact damage than the heavy ones. Furthermore, damping is found to be more sensitive to damage than the stiffness variations, so it is reasonable to assume that damping may be used instead of natural frequency as a damage indicator tool for structural health monitoring purposes.     

Solar-assisted smokehouse for the drying of natural rubber on small-scale Indonesian farms

Natural rubber in Indonesia is mainly produced by smallholder farmers and—being the highest foreign currency generating agricultural commodity—is of great importance for the Indonesian economy. Nevertheless, due to the lack of appropriate dryers, more than 80% of the total production has to be sold as low-grade Standard Indonesian Rubber (SIR) for a relatively low price.In order to improve the product quality, a solar-heated rubber sheet dryer was developed. It consists of a flat-plate solar air heater connected to a drying chamber. Part-recirculation of the exhaust air leads to the desired drying air temperature of 45–60°C and results in a significant reduction of the drying time. To enable drying independent of weather conditions, a biomass furnace was incorporated underneath the drying chamber.The tests have shown that during the rainy season, 320 kg of sheets can be uniformly dried to the required moisture content of 0.5% within 5 days. Compared with conventional smokehouses, the firewood consumption could be considerably reduced, from 1.0–1.5 kg per kg dry rubber to 0.3 kg when producing Ribbed Smoked Sheets (RSS). A further reduction can be expected by optimization of the heating intervals. During favourable weather conditions Air Dried Sheets (ADS) can be produced within 6–7 days without supplemented heat. The quality of the RSS and ADS fulfills the international standards.The simple design of the solar-assisted smokehouse allows local production and—after further improvements—seems to be an economical alternative for farmer groups or nucleus estates.     

Local cosine transform — a method for the reduction of the blocking effect in JPEG

This paper presents the local cosine transform (LCT) as a new method for the reduction and smoothing of the blocking effect that appears at low bit rates in image coding algorithms based on the discrete cosine transform (DCT). In particular, the blocking effect appears in the JPEG baseline sequential algorithm.Two types of LCT were developed: LCT-IV is based on the DCT type IV, and LCT-II is based on DCT type II, which is known as the standard DCT. At the encoder side the image is first divided into small blocks of pixels. Both types of LCT have basis functions that overlap adjacent blocks. Prior to the DCT coding algorithm a preprocessing phase in which the image is multiplied by smooth cutoff functions (or bells) that overlap adjacent blocks is applied. This is implemented by folding the overlapping parts of the bells back into the original blocks, and thus it permits the DCT algorithm to operate on the resulting blocks. At the decoder side the inverse LCT is performed by unfolding the samples back to produce the overlapped bells. The purpose of the multiplication by the bell is to reduce the gaps and inaccuracies that may be introduced by the encoder during the quantization step.LCT-IV and LCT-II were applied on images as a preprocessing phase followed by the JPEG baseline sequential compression algorithm. For LCT-IV, the DCT type IV replaced the standard DCT as the kernel of the transform coding. In both cases, for the same low bit rates the blocking effect was smoothed and reduced while the image quality in terms of mean-square error became better. Subjective tests performed on a group of observers also confirm these results. Thus the LCT can be added as an optional step for improving the quality of existing DCT (JPEG) encoders. Advantages over other methods that attempt to reduce the blocking effect due to quantization are also described.     

Reduced-Memory Direct Digital Frequency Synthesizer Using Parabolic Initial Guess

Based on the parabolic approximation, which was recently introduced by the authors, a new architecture for sine-output direct digital frequency synthesizers has been developed. Due to using this approximation, and also considering several memory-reduction techniques, the proposed architecture is so designed that needs only 728 bits read-only memory for mapping a 12-bit phase address to 10-bit sine amplitude. The synthesizer has also been implemented and the experimental results show its desired operation and performance.     

Improving access to family support organizations: a member survey of the AMI-Quebec Alliance for the Mentally Ill

Family support organizations such as the Quebec Alliance for the Mentally Ill (AMI-Quebec) provide services for mentally ill individuals and their families. Despite possible benefits, there is often a lengthy period between identification of mental illness and involvement of family members with family support organizations. A survey of AMI-Quebec members was undertaken to assess this delay. Of the 186 respondents, 47 percent experienced a delay of more than two years. Only 10 percent were referred to the organization by psychiatrists. The majority would have liked to have become involved with AMI-Quebec earlier. Some approved of more proactive methods of recruitment by AMI-Quebec, such as a telephone call after an initial hospitalization.     

Extremely-Wide-Range Supply-Independent CMOS Voltage References for Telemetry-Powering Applications

This paper reports a voltage reference circuit in standard CMOS process. It exhibits excellent supply independency for a wide input voltage range, which is of great importance in telemetry-powered systems. This circuit is based on the well-known V_GS-reference supply-independent current reference circuit, but it is designed to serve as a voltage reference. While the reference current generated by this circuit varies with the supply voltage, a self-compensating mechanism can be found in voltage-mode operation of the circuit that results in a supply-independent reference voltage. This supply independency is well observed in the static operation of the circuit over an extremely wide input range, as well as in its dynamic behavior for high frequency ripples on the input voltage. Based on the proposed idea, a multi-output voltage reference and a CMOS DC level shifter are also designed. The proposed voltage reference circuits have been fabricated using MOSIS 1.6 μm standard CMOS process. The basic voltage reference provides 957 μV/V static supply dependency, rejects input ripples of up to 8 MHz by 60± 3dB, and consumes only 15.8–36.9 μA when the input voltage varies in the range 2.6–12 V. Amir M. Sodagar received the B.S. degree from K.N. Toosi (KNT) University of Technology, Tehran, Iran, and M.S. and Ph.D. degrees from Iran University of Science & Technology (IUST), Tehran, Iran all in Electrical Engineering in 1992, 1995, and 2000, respectively. From 1992 to 2000 he was with S. Rajaee University as a Lecturer. After receiving the Ph.D. degree until 2002 he was with the NSF Engineering Research Center for Wireless Integrated Micro Systems (WIMS), Electrical Engineering & Computer Science (EECS) Dept., University of Michigan as a Post-Doctoral Research Fellow. From 2002 to 2004 he was with S. Rajaee University and KNT University of Technology as an Assistant Professor and an Adjunct Professor, respectively, and since 2004 he has been with the University of Michigan as an Associate Visiting Research Scientist. Dr. Sodagar was known as the Outstanding Electrical Engineering Graduate Student of the IUST in 1995, and receiv ed the IUST's Best Ph.D. Research Achievement Award in 2000. He was also the recipient of S. Rajaee University's Distinguished Faculty Member Award for “1998–1999” and “1999–2000” academic years, and S. Rajaee University's Distinguished Researcher Award for “2002–2003” academic year. He was involved in the design of integrated circuits in collaboration with the Center for Semiconductor Research and Fabrication from 1994 to 1995, VLSI Circuits & Systems Laboratory at the University of Tehran from 1997 to 1998, and EMAD Semicon Company from 1998 to 2000. He has authored one book, authored/co-authored more than 20 journal and conference papers, and served as the technical paper reviewer for several IEEE journals/transactions and also conferences. Dr. Sodagar's research interests are generally in the field of mixed-signal integrated circuit design, and focused on: integrated circuits for neural recording & stimulation, telemetry powering and control of implantable microsystems, frequency synthesizers, analog building blocks, and transistor-level implementations of digital logic families. Khalil Najafi (IEEE S '84, M '86, SM '97, F'00) received the B.S., M.S., and the Ph.D. degree in 1980, 1981, and 1986 respectively, all in Electrical Engineering from the Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor. From 1986–1988 he was employed as a Research Fellow, from 1988–1990 as an Assistant Research Scientist, from 1990–1993 as an Assistant Professor, from 1993–1998 as an Associate Professor, and since September 1998 as a Professor and the Director of the Solid-State Electronics Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan. His research interests include: micromachining technologies, micromachined sensors, actuators, and MEMS; analog integrated circuits; implantable biomedical microsystems; micropackaging; and low-power wireless sensing/actuating systems. Dr. Najafi was awarded a National Science Foundation Young Investigator Award from 1992–1997, was the recipient of the Beatrice Winner Award for Editorial Excellence at the 1986 International Solid-State Circuits Conference, of the Paul Rappaport Award for co-authoring the Best Paper published in the IEEE Transactions on Electron Devices, and of the Best Paper Award at ISSCC 1999. In 2003 he received the EECS Outstanding Achievement Award, in 2001 he received the Faculty recognition Award, and in 1994 the University of Michigan's “Henry Russel Award” for outstanding achievement and scholarship, and was selected as the “Professor of the Year” in 1993. In 1998 he was named the Arhtur F. Thurnau Professor for outstanding contributions to teaching and research, and received the College of Engineering's Research Excellence Award. He has been active in the field of solid-state sensors and actuators for more than twenty years, and has been involved in several conferences and workshops dealing with solid-state sensors and actuators, including the International Conference on Solid-State Sensors and Actuators, the Hilton-Head Solid-State Sensors and Actuators Workshop, and the IEEE/ASME Micro Electromechanical Systems (MEMS) Conference. Dr. Najafi is the Editor for Solid-State Sensors for IEEE Transactions on Electron Devices, an Associate Editor for the Journal of Micromechanics and Microengineering, Institute of Physics Publishing, and an editor for the Journal of Sensors and Materials. He also served as the Associate Editor for IEEE Journal of Solid-State Circuits from 2000–2004, and the associate editor for IEEE Trans. Biomedical Engineering from 1999–2000. He is a Fellow of the IEEE.