Effects of Prenatal Exposure to a 50-Hz Magnetic Field on One-Trial Passive Avoidance Learning in 1-Day-Old Chicks

We investigated memory impairment in newly hatched chicks following in ovo exposure to a 50-Hz magnetic field (MF) of 2 mT (60 min/day) on embryonic days 12-18. Isolated and paired chicks were used to test the effect of stress during training, and memory retention was tested at 10, 30, and 120 min, following exposure to a bitter-tasting bead (100% methylanthranilate). Results showed that memory was intact at 10 min in both isolated and paired chicks with or without MF exposure. However, while isolated chicks had good memory retention levels at 30 and 120 min, those exposed to MF did not. The results suggest a potential disruption of memory formation following in ovo exposure to MF, with this effect only evident in the more stressed, isolated chicks. Bioelectromagnetics 31:150-155, 2010. (C) 2009 Wiley-Liss. Inc.

Seawater irrigation systems for intensive marine shrimp farming in Thailand

The aim of the seawater irrigation system (SIS) is to clean up shrimp pond effluent and provide high quality seawater for shrimp farming. The system has 3 components: water intake; treatment reservoir and discharge system. There are criteria for site selection because shrimp farmers are required to form associations so they can work closely together. The construction site must be on the coastal area outside a mangrove forest and located away from a production agricultural area. All construction sites must have undergone an environmental impact assessment, and should be located on the area listed in Thailand's Coastal Zone Management Plan. Five SIS projects, which cover a culture area of 6,500 ha with 1,300 farmers (families), were completed and operated. The Department of Fisheries has planned for another 28 projects, that will cover almost 44,000 ha of culture area.

Passive control of combustion instability in a low emissions aeroderivative gas turbine

This paper describes the conceptual ideas, the theoretical validation, the laboratory testing and the field trials of a recently patented fuel-air mixing device for use in high-pressure ratio, low emissions, gaseous-fueled gas turbines. By making the fuel-air mixing process insensitive to pressure fluctuations in the combustion chamber, it is possible to avoid the common problem of positive feedback between mixture strength and the unsteady combustion process. More specifically, a mixing duct has been designed such that fuel-air ratio fluctuations over a wide range of frequencies can be damped out by passive design means. By scaling the design in such a way that the range of damped frequencies covers the frequency spectrum of the acoustic modes in the combustor, the instability mechanism can be removed. After systematic development, this design philosophy was successfully applied to a 35:1 pressure ratio aeroderivative gas turbine yielding very low noise levels and very competitive NOx and CO measurements. The development of the new premixer is described from conceptual origins through analytic and CFD evaluation to laboratory testing and final field trials. Also included in this paper are comments about the practical issues of mixing, flashback resistance and autoignition.

Reversible disconnection of the hippocampal-prelimbic cortical circuit impairs spatial learning but not passive avoidance learning in rats

Wistar rats, treated with the GABA(A) receptor agonist muscimol, were used to investigate the role of the hippocampal-prelimbic cortical (Hip-PLC) circuit in spatial learning in the Morris water maze task, and in passive avoidance learning in the step-thr

Active-passive 44 SOA-based switch with integrated power monitoring

The first monolithically integrated 44 switch with power monitoring function using on-chip PIN photodiodes is reported. Using 10Gb/s signals, under active power control an IPDR of 12dB for a 1dB power penalty is achieved. © 2012 OSA.

An error free passive UHF RFID system using a new form of wireless signal distribution

A wide area and error free ultra high frequency (UHF) radio frequency identification (RFID) interrogation system based on the use of multiple antennas used in cooperation to provide high quality ubiquitous coverage, is presented. The system uses an intelligent distributed antenna system (DAS) whereby two or more spatially separated transmit and receive antenna pairs are used to allow greatly improved multiple tag identification performance over wide areas. The system is shown to increase the read accuracy of 115 passive UHF RFID tags to 100% from <60% over a 10m × 8m open plan office area. The returned signal strength of the tag backscatter signals is also increased by an average of 10dB and 17dB over an area of 10m 8m and 10m × 4m respectively. Furthermore, it is shown that the DAS RFID system has improved immunity to tag orientation. Finally, the new system is also shown to increase the tag read speed/rate of a population of tags compared with a conventional RFID system. © 2012 IEEE.

Passive suspensions incorporating inerters for railway vehicles

This paper investigates the possibility of improving the performance of railway vehicle suspensions by incorporating a newly developed mechanical device known as the inerter. A comparative study of several low-complexity passive suspension layouts is made. Improved performance for the lateral and vertical ride comfort, as well as lateral body movement when curving are demonstrated in comparison with the conventional suspension layout. The constraints imposed are to maintain the same level of other performance metrics. The calculations and optimisations are based on linearised plan-view and side-view high-speed train mathematical models. © 2012 Copyright Taylor and Francis Group, LLC.

A theoretical approach to the passive control of spiral vortex breakdown

Previous numerical simulations have shown that vortex breakdown starts with the formation of a steady axisymmetric bubble and that an unsteady spiralling mode then develops on top of this.We study how this spiral mode of vortex breakdown might be suppressed or promoted. We use a Lagrangian approach to identify regions of the flow which are sensitive to small open-loop steady and unsteady (harmonic) forces. We find these regions to be upstream of the vortex breakdown bubble. We investigate passive control using a small axisymmetric control ring. In this case, the steady and unsteady control forces are caused by the drag force on the control ring. We find a narrow region upstream of the bubble where the control ring will stabilise the flow and we verify this using numerical simulations. © 2012 IEEE.

Hybrid passive/active inertial actuators to attenuate the structural response of a submerged hull

This paper theoretically investigates the application of tuned vibration absorbers and hybrid passive/active inertial actuators to reduce the vibrational responses of plates and shells. The passive/active actuators are initially applied to a simple plate. A model of a submerged hull consisting of a ring stiffened finite cylinder with bulkheads and external fluid loading is then considered. The fluctuating forces from the propeller result in excitation of the low frequency global hull modes. Inertial actuators and tuned vibration absorbers are located at each end of the hull and in circumferential arrays to reduce the hull structural response at its axial resonances. The control performance of the hybrid passive/active inertial actuator, where the passive component is tuned to a structural resonance, is compared to the attenuation achieved by a fully passive tuned vibration absorber. This work shows the potential of using hybrid passive/active inertial actuators to attenuate the global structural responses of a submerged vessel.

Wide Area Passive UHF RFID System using Antenna Diversity Combined with Phase and Frequency Hopping

This paper presents a long range and effectively error-free ultra high frequency (UHF) radio frequency identification (RFID) interrogation system. The system is based on a novel technique whereby two or more spatially separated transmit and receive antennas are used to enable greatly enhanced tag detection performance over longer distances using antenna diversity combined with frequency and phase hopping. The novel technique is first theoretically modelled using a Rician fading channel. It is shown that conventional RFID systems suffer from multi-path fading resulting in nulls in radio environments. We, for the first time, demonstrate that the nulls can be moved around by varying the phase and frequency of the interrogation signals in a multi-antenna system. As a result, much enhanced coverage can be achieved. A proof of principle prototype RFID system is built based on an Impinj R2000 transceiver. The demonstrator system shows that the new approach improves the tag detection accuracy from <50% to 100% and the tag backscatter signal strength by 10dB over a 20 m x 9 m area, compared with a conventional switched multi-antenna RFID system.

An Error Free Passive UHF RFID System using a New Form of Wireless Signal Distribution

A wide area and error free ultra high frequency (UHF) radio frequency identification (RFID) interrogation system based on the use of multiple antennas used in cooperation to provide high quality ubiquitous coverage, is presented. The system uses an intelligent distributed antenna system (DAS) whereby two or more spatially separated transmit and receive antenna pairs are used to allow greatly improved multiple tag identification performance over wide areas. The system is shown to increase the read accuracy of 115 passive UHF RFID tags to 100% from <60% over a 10m x 8m open plan office area. The returned signal strength of the tag backscatter signals is also increased by an average of 10dB and 17dB over an area of 10m x 8m and 10m x 4m respectively. Furthermore, it is shown that the DAS RFID system has improved immunity to tag orientation. Finally, the new system is also shown to increase the tag read speed/rate of a population of tags compared with a conventional RFID system.

Demonstration of Improved Passive UHF RFID Coverage using Optically-Fed Distributed Multi-Antenna System

Optically-fed distributed antenna system (DAS) technology is combined with passive ultra high frequency (UHF) radio frequency identification (RFID). It is shown that RFID signals can be carried on directly modulated radio over fiber links without impacting their performance. It is also shown that a multi-antenna DAS can greatly reduce the number of nulls experienced by RFID in a complex radio environment, increasing the likelihood of successful tag detection. Consequently, optimization of the DAS reduces nulls further. We demonstrate RFID tag reading using a three antenna DAS system over a 20mx6m area, limited by building constraints, where 100% of the test points can be successfully read. The detected signal strength from the tag is also observed to increase by an average of approximately 10dB compared with a conventional switched multi-antenna RFID system. This improvement is achieved at +31dBm equivalent isotropically radiated power (EIRP) from all three antenna units (AUs).

A Novel Passive UHF RFID Real Time Location Sensing System

Ubiquitous in-building Real Time Location Systems (RTLS) today are limited by costly active radio frequency identification (RFID) tags and short range portal readers of low cost passive RFID tags. We, however, present a novel technology locates RFID tags using a new approach based on (a) minimising RFID fading using antenna diversity, frequency dithering, phase dithering and narrow beam-width antennas, (b) measuring a combination of RSSI and phase shift in the coherent received tag backscatter signals and (c) being selective of use of information from the system by, applying weighting techniques to minimise error. These techniques make it possible to locate tags to an accuracy of less than one metre. This breakthrough will enable, for the first time, the low-cost tagging of items and the possibility of locating them at relatively high precision.