Applications In Various Environments Research Articles

Temperature-Dependent Properties of a 1–3 Connectivity Piezoelectric Ceramic–Polymer Composite

Abstract In this work, the 1–3 connectivity piezoelectric ceramic–polymer composites have been fabricated by a viscous-polymer processing, where 0.90Pb(Zr0.52Ti0.48)O3–0.05Pb(Mn1/3Sb2/3)O3–0.05Pb(Zn1/3Nb2/3)O3 (PZT–PMS–PZN) fibers with 0.5 volume fraction were aligned in epoxy matrix. The sintered PZT fibers, with average diameter of 300 μm and aspect ratio (height/diameter) higher than 3, all showed a pure perovskite phase structure and highly dense morphology. The dielectric, piezoelectric, ferroelectric properties and the vibration modes of the 1–3 composites were measured and demonstrated in comparison with that of the monolithic piezoelectric ceramics. The results confirmed that the 1–3 composites possessed a low acoustic impedance (Z) of 13 MRayl and a high thickness coupling coefficient (k t) of 0.59, in addition, only single thickness vibration mode with the resonance frequency over 1.5 MHz was observed. With temperature elevation, the properties including dielectric constant εr , k t, the ratio of k t to k p (k t/k p) and the acoustic impedance (Z) increase, while the planar electromechanical coupling coefficient (k p) show opposite temperature dependence. Under test temperature of 100°C, the 1–3 composites still present excellent temperature stability with increased k t/k p ratio up to 3.6. The researches on temperature-dependent properties of the 1–3 composites are critical for improving its applications in various environments.

Design of a H2/O2 biofuel cell based on thermostable enzymes

A new generation of mediatorless H2/O2 biofuel cells was designed based on a hyperthermophilic O2-tolerant hydrogenase and a thermostable bilirubin oxidase both immobilized on carbon nanofibers. A power density up to 1.5±0.2mW·cm−2 at 60°C was reached. This first demonstration of a H2/O2 biofuel cell able to deliver electricity over a wide range of temperatures, from 30°C up to 80°C, and over a large pH window, allows considering this device as an alternative power supply for small portable applications in various environments, including extreme ones.

다중 디바이스에서 손 인식을 통한 선택적 제어

최근 사용자와 컴퓨터 간의 상호작용을 통하여 컴퓨터를 제어하는 시스템이 활발하게 연구되고 있으며, 특히 사람의 손 인식에 관한 연구가 많이 이루어지고 있다. 현재까지는 하나의 디바이스에서 사람의 손인식 정확도를 높이는 연구와 손동작을 통하여 디바이스를 제어하는 연구가 주를 이루고 있지만, 손 인식 기술이 여러 산업분야에 적용됨에 따라 다양한 환경과 상황에 적용하기 위하여 다중 디바이스 간의 시스템을 선택적으로 제어하는 연구가 필요하다. 본 논문에서는 사용자의 손 인식을 통하여 두 개의 디바이스 중에서 선택적으로 하나의 디바이스를 제어하고자 한다. 더불어 6가지의 조건을 포함한 환경에서 실험을 통해 두 디바이스 간의 선택적 손 인식의 성공률을 높이기 위한 환경을 제시하고자 한다. Extensive researches on PC control system via interaction between PC and users are being conducted recently, especially on human finger recognition in the electronic devices. Heretofore, researches on methods to improve the accuracy of finger recognition in a single device and to control the devices with it have been the mainstream, whereas many different industries where finger recognition become more utilized are demanding researches on methods to selectively control the system of multiple devices for applications in various environments and situations. This article demonstrates attempts to selectively control one of two devices through finger recognition. Along with this, experiments conducted with 6 variable conditions are demonstrated here, where the optimal condition to increase the rate of successful selective finger recognition between two devices is studied.

Low-cost small scale processing technologies for production applications in various environments—Mass produced factories

The requirements for chemical and food production technologies will change in the future as a result of shorter time to market and increasing market volatility. Especially the rising use of renewable resources will require the implementation of flexible and fast to install small-scale production technologies. The increasing number of necessary apparatuses and their distributed operation, however, will constitute major challenges, both economically and procedurally. The proposed solution to face the economic challenge is modularization and standardization. For food production, dewatering represents a key issue. Thus, biomass processing should first be divided into small-scale water separation steps and then into further large-scale processing steps. As dewatering usually happens thermally and heat exchangers often benefit from the economies of scale, heat supply and energy consumption or heat transfer with little capital investment are further issues. Therefore, temperature levels should be decreased and the use of solar heat increased. For the production of biofuels and chemicals from biomass, process integration and process simplification are proposed to improve the efficacy of production equipment and processes. Choosing raw materials with molecular structures, similar to the desired chemical building block, will lower the need for heat exchange and make small-scale manufacturing of fuels and chemicals possible.

Characterization of nanostructured coatings based on oxides for tribological applications

The aim of this project was to develop a wear-resistant coating for tribological applications in various environments. Zirconia nanocrystallites were encapsulated into an amorphous Cu matrix by the simultaneous deposition of Zr and Cu with pulsed reactive magnetron sputtering. The incorporation of ZrO2 in a Cu matrix leads to a nanocomposite coating with improved wear resistance, temperature stability and chemical inertness. The deposition parameters (cathodes power, gas flow) were correlated to the mechanical properties of the coating. The nanoparticles were deposited onto metal-grids and analyzed by transmission electron microscopy. Sliding tests were performed under N2 and with Isopar M as lubricant. The coatings were tested against steel 100Cr6 and ceramic Al2O3 counterparts. The wear mechanism was studied in each situation.

Characterization of nanostructured coatings based on oxides for tribological applications

The aim of this project was to develop a wear-resistant coating for tribological applications in various environments. Zirconia nanocrystallites were encapsulated into an amorphous Cu matrix by the simultaneous deposition of Zr and Cu with pulsed reactive magnetron sputtering. The incorporation of ZrO 2 in a Cu matrix leads to a nanocomposite coating with improved wear resistance, temperature stability and chemical inertness. The deposition parameters (cathodes power, gas flow) were correlated to the mechanical properties of the coating. The nanoparticles were deposited onto metal-grids and analyzed by transmission electron microscopy. Sliding tests were performed under N 2 and with Isopar M as lubricant. The coatings were tested against steel 100Cr6 and ceramic Al 2O 3 counterparts. The wear mechanism was studied in each situation.

擬ＨＩＰ‐放電焼結法による金属射出成形体のニアネットシェイプ固化成形

The consolidation of injection molded compacts by Pulsed Discharge Sintering Process, that enables rapid sintering under the condition of high temperature combined with pressure application in various environments, is proposed as a novel process of near net forming. The proposed PHIP (Pseudo Hot Isostatic Pressing) technique using a pressure-transmitting medium of spherical graphite powder makes it possible to manufacture compacts with three dimensional shapes (PHIP-PDS). For the first time, temperature distribution along radial direction of graphite die was measured in the real time under PHIP-PDS. There existed temperature gradient in the die, that depended on holding temperature, inside diameter and thickness of die. Titanium powders, mixed with 36.2 vol% organic binder, were injection molded. After debound in 100 Torr Ar atmosphere at various temperature, they were consolidated by PHIP-PDS process. The temperature necessary to fully densify them under 50 MPa pressure was 1373K for PHIP-PDS, which was about 300K higher than that for PDS. Contraction percentage of the compacts was 25% for longitudinal (loading) direction, while 6% for transverse direction. Chemical analysis of titanium compacts showed 0.12-0.17wt% carbon and 0.22-0.28wt% oxygen.

A new method for measuring near-surface moisture budgets in hydrological systems

Preliminary results from a groundwater experiment set up near Matamata (New Zealand) reveal that confined aquifers can act as giant weighing lysimeters, with pore water pressures giving real-time measures of changes in amounts of surface and near-surface water. This opens the possibility of water balance studies at the scale of hectares using measurements from a single site. Given suitable confined aquifers, the technique has application in various environments for hydrological measurements as diverse as quantification of evapotranspiration loss, areal precipitation measurement, monitoring the water content of an accumulating snowpack, and net lateral groundwater transfers in unconfined aquifers.