Jyh-Cherng Shieh

A GSM-based Field Monitoring System for Spodoptera litura (Fabricius)*

The hot and humid weather of Taiwan causes a wide spread of pests and a great loss to Taiwans agriculture. In particular, Spodoptera litura (Fabricius) causes huge agricultural disasters in past years. To gather important information related to the outbreak of S. litura, we develop an ecological monitoring system which combines GSM transmission technologies with mechatronics. The proposed system also equips with an MSP430 low-power microcontroller, a solar power supply system, and a trapping tube. All information collected by the system is stored in a specially designed database. The system is then deployed at an outdoor environment to verify its reliability. The test results show that the system is capable of providing effective monitoring information for pest management.

Intricate straining of manganese-doped (Bi0.5Na0.5)TiO3–BaTiO3–(Bi0.5K0.5)TiO3 lead-free ferroelectric ceramics

The strain hystereses of lead-free a(Bi0.5Na0.5)TiO3–bBaTiO3–c(Bi0.5K0.5)TiO3 (abbreviated as BNBK 100a/100b/100c) ferroelectric compositions inside and outside the morphotropic phase boundary (MPB) were investigated previously by the authors, and it was found that BNBK 85.4/2.6/12, a composition well within the MPB, possesses notable actuating properties such as an induced electrostrain of about 0.14%. In this study, BNBK 85.4/2.6/12 is doped with various amounts of manganese (Mn) to improve its sinterability and ferroelectric characteristics. Intricate strain hysteresis behaviours are observed upon Mn doping—an electrostrain of above 0.1% can be maintained when the Mn doping amount is between 0.5 and 1.5 mol%. Once outside this doping range, the induced electrostrain is considerably smaller. By examining the evolution of crystalline phase composition with Mn doping, the mole content of the rhombohedral phase is shown for the first time to be a critical factor in deciding the straining behaviours of the Mn-doped BNBK 85.4/2.6/12 ceramics. To each increasing step in Mn doping level, there is a marked similarity in the evolutions of the induced electrostrain and rhombohedral phase content. The rhombohedral ferroelectric phase possesses more equivalent crystallographic directions for non-180° polarization switching, and accordingly, the Mn-doped BNBK compositions with relatively higher rhombohedral phase contents exhibit larger electrostrains.

Design and Fabrication of 2D Phononic Crystals in Surface Acoustic Wave Micro Devices

In this paper, we present the design and fabrication of innovative phononic crystals integrated with two sets of interdigital (IDT) electrodes for frequency band selection of surface acoustic waves (SAW). The potential applications of this device include performance improvement of SAW micro-sensors, front-end components in RF circuitries, and directional receptions of high frequency acoustic waves. Analogous to the band-gap generated by photonic crystals, the phononic crystals, two dimensional repetitive structures composed of two different elastic materials, can prohibit the propagation of elastic waves with either specific incident angles or certain bandwidth. In this paper, the prohibited bandwidth has been verified by fabricating the phononic crystals between a micromachined SAW resonator and a receiver. Both the resonator and receiver are composed of IDT electrodes deposited and patterned on a thin piezoelectric layer. To confine the prohibited bandwidth on the order of hundred MHz, the diameter of the circular pores in phononic crystals is designed to be 6 micron and the aspect ratio of each pore is 3:1. To maximize the power transduction from IDT electrodes to SAW, the spacing between two inter-digits is one-fourth the wavelength of SAW. Specifically, the spacing ranges from 3.4 microns to 9.0 microns, depending on the central frequency. Both surface and bulk micromachining are employed and integrated to fabricate the crystals as well as SAW resonator and receiver altogether. Firstly, a 1.5-micron zinc oxide, which provides well-defined central frequency, is sputtered and patterned onto silicon substrate.

Design and Fabrication of 2D Phononic Crystals in Surface Acoustic wave Micro Devices

In this paper, we present the design and fabrication of innovative phononic crystals integrated with two sets of interdigital (IDT) electrodes for frequency band selection of surface acoustic waves (SAW). The potential applications of this device include performance improvement of SAW micro-sensors, front-end components in RF circuitries, and directional receptions of high frequency acoustic waves. Analogous to the band-gap generated by photonic crystals, the phononic crystals, two dimensional repetitive structures composed of two different elastic materials, can prohibit the propagation of elastic waves with either specific incident angles or certain bandwidth. In this paper, the prohibited bandwidth has been verified by fabricating the phononic crystals between a micromachined SAW resonator and a receiver. Both the resonator and receiver are composed of IDT electrodes deposited and patterned on a thin piezoelectric layer. To confine the prohibited bandwidth on the order of hundred MHz, the diameter of the circular pores in phononic crystals is designed to be 6 micron and the aspect ratio of each pore is 3:1. To maximize the power transduction from IDT electrodes to SAW, the spacing between two inter-digits is one-fourth the wavelength of SAW. Specifically, the spacing ranges from 3.4 microns to 9.0 microns, depending on the central frequency. Both surface and bulk micromachining are employed and integrated to fabricate the crystals as well as SAW resonator and receiver altogether. Firstly, a 1.5-micron zinc oxide, which provides well-defined central frequency, is sputtered and patterned onto silicon substrate.

A WSN-based wireless monitoring system for intradialytic hypotension of dialysis patients

Intradialytic hypotension (IDH) is a much common complication during a hemodialysis. The prevalence of IDH is about 10–50%. Elderly people, patients with diabetes, and cardiovascular dialysis patients have the highest rate of incidences. IDH may lead to nausea, vomiting, or anxiety. In some severe cases, there will be accident like shock and death. The purpose of this paper is to integrate the technologies of wireless sensor networks (WSN) technologies, global systems for mobile communications (GSMs), and a database to construct an automatic monitoring system to collect physical data during hemodialysis. We then apply this wireless monitoring technology to the patients with IDH. During hemodialysis simulations, the average success ratio of physical data transmitting is 94.841%, where the testing cases are collected from 6 persons, and the time interval is 2 hours. The loss ratio of physical data results from space constraints and data collision.

An application of the wireless sensor network technology for foehn monitoring in real time

Foehn is one of the common climate phenomena in Taiwan because of geographical factors. The foehn is associated with high temperature and low humidity, which often leads to plant death and even causes serious forest fires. The natural disaster relief fund in Taiwan has covered the loss caused by the foehn. However, no monitoring system has been developed for the foehn, so farmers are not able to immediately obtain foehn-related information and activate necessary schemes for disaster reduction. The research aims at foehn detection and uses the wireless sensor network technology to build a real-time system to monitor foehn. Since the characteristics of wireless sensor networks are low costs, unmanned control and transmission distance up to 80 meters, it is feasible to apply the networks to environmental monitoring. When foehn occurs, the wireless communication devices in the proposed monitoring system will transmit the temperature and humidity information collected by monitoring stations to the gateway module, and sprinkler module action immediately for cooling and increasing humidity to protect the plants from pericarp damage or fruit drop phenomenon caused by foehn.

Relationship between the evolutions of the microstructure and semiconductor properties of yttrium-doped barium titanate ceramics

Intricate connections among the microstructural effect, semiconducting tendency and charge compensation behaviour of yttrium (Y3+) dopants in near-stoichiometric barium titanate (BaTiO3; Ba/Ti atomic ratio = 0.999) ceramics sintered at 1460 °C in air are examined. It is found that with increasing Y3+ doping up to 2.0 mol%, the microstructure of BaTiO3 evolves from a liquid-phase-assisted dense-sintered microstructure to a highly porous microstructure characterized by connected pores and loose lattices of fused submicrometre grains. During such evolution, a transitional microstructure characterized by large distinctive pores and grains with abnormal morphology is also identified. When Y3+ doping is increased progressively from 0.02 to 0.2 mol%, the (negative) majority carrier concentration and conductivity are increased substantially by 8 orders of magnitude. This increase in n-type semiconductor characteristics is contributed not only by the increasing substitution of Y3+ for Ba2+ in host BaTiO3, but also by the formation of yttrium-rich and/or oxygen-deficient precipitates at the grain boundaries. The grain boundary phases would therefore stabilize the mechanism of free electron compensation and enable the transportation of electrons through the grain boundaries. The measured Hall effect data indicate the shift from the n-type to p-type semiconductor properties with increasing Y3+ doping. The carrier mobilities of 1.0 and 2.0 mol% Y-doped BaTiO3 are high; this is attributed to their highly porous microstructures which provide easy diffusion paths for the charge carriers. Through a combined interpretation of the diffractometry, microscopy, mass spectrometry and Hall effect data, Y3+ doping at 1.0 mol% is found to be the critical doping amount separating different site-occupying behaviours of Y3+ in the BaTiO3 cation sites, which eventually lead to different charge compensation mechanisms and semiconductor properties.

A novel coverage-preserving algorithm with energy efficiency

Deploying wireless sensor networks (WSNs) has been an area of interest in recent years. Adoption of WSNs with energy efficiency is a critical issue since the energy of sensor nodes is usually rather limited. Energy-efficient coverage control is regarded as an essential factor influencing the performance of WSNs. Coverage might gradually degrade after the activation of WSNs. Thus, a novel coverage-preserving algorithm (CPA) that is able to prolong the lifetime and to maximize the coverage is proposed in this study. The new scheme turns redundant nodes off according to the optimal arrangement based on a Memetic Algorithm (MA), and awakens some inactive nodes at proper time to recover the lost coverage due to the node failure or energy exhaustion. Simulation results via a cluster-based WSN (CWSN) show that the performance of the suggested algorithm is promising in terms of energy efficiency and coverage preservation.

A Simulation System for Flexible Manufacturing Cells

Based on the Local Area Network concept, four sets of IBM-PC are used to form a simulation system for a flexible manufacturing cell, which consists of a milling machine, a turning machine, an industrial robot and two pallet stands.