In this work, the use of magnetic induction (MI) to cross the air-water boundary is investigated. An analytical expression is derived for the magnetic field in air from a coil underwater and is ...validated with simulation results that also include the effect of the front-end. Specifically, the ratio of the induced voltage of the receiver over transmitter current is maximized for a given distance between small coils with a radius of 6.5 cm and it is found that an optimal frequency exists: for a distance between 10 and 100 m, the optimum frequency of operation decreases from 8000 down to 80 Hz. Experiments are performed in air and in sea-water tanks to verify the mutual inductance and end-to-end attenuation. The experiments agree with the theory for distances up to 1.6 m, after which a noise floor is reached. To increase the range, the use of passive repeaters is studied and a relay coil that transfers the energy to a receiver inside a magnetic shield is analyzed. When configured correctly, this relay can significantly enhance the receiver output voltage, as demonstrated through simulations, potentially increasing it by up to tenfold.
This article presents a channel state information acquisition approach based on a Markov chain process that exploits information from the physical environmental conditions, including the tide phase ...and flow. The method is intended to predict channel characteristics, including the gain, delay, and Doppler spread, as well as the standard deviation of intrapath delays in time-varying conditions. Specifically, the correlation between different oceanic processes and the acoustic channel characteristics is confirmed to define a set of tide-dependent states corresponding to a particular channel condition. Channel soundings from a 34-day sea trial conducted in Grand Passage, Nova Scotia, are used to derive the channel characteristics statistics. For this purpose, channel soundings measurements are applied to a parametric model of the propagation channel. The probabilistic parametric model forms a data set by characterizing the time-varying channel impulse response and describing the channel tapped-delay structure statistically as a function of different tide phases. The proposed Markov chain is driven by the measured channel data set and predicts the future channel characteristics one tide cycle ahead. To validate the accuracy of the proposed method, the predicted channel characteristics are compared to the channel measurements obtained in a 566-m channel in Grand Passage, Nova Scotia.
A series of Zr‐based UiO‐n MOF materials (n=66, 67, 68) have been studied for iodine capture. Gaseous iodine adsorption was collected kinetically from a home‐made set‐up allowing the continuous ...measurement of iodine content trapped within UiO‐n compounds, with organic functionalities (−H, −CH3, −Cl, −Br, −(OH)2, −NO2, −NH2, (−NH2)2, −CH2 NH2) by in‐situ UV‐Vis spectroscopy. This study emphasizes the role of the amino groups attached to the aromatic rings of the ligands connecting the {Zr6O4(OH)4} brick. In particular, the preferential interaction of iodine with lone‐pair groups, such as amino functions, has been experimentally observed and is also based on DFT calculations. Indeed, higher iodine contents were systematically measured for amino‐functionalized UiO‐66 or UiO‐67, compared to the pristine material (up to 1211 mg/g for UiO‐67‐(NH2)2). However, DFT calculations revealed the highest computed interaction energies for alkylamine groups (−CH2NH2) in UiO‐67 (−128.5 kJ/mol for the octahedral cavity), and pointed out the influence of this specific functionality compared with that of an aromatic amine. The encapsulation of iodine within the pore system of UiO‐n materials and their amino‐derivatives has been analyzed by UV‐Vis and Raman spectroscopy. We showed that a systematic conversion of molecular iodine (I2) species into anionic I− ones, stabilized as I−⋅⋅⋅I2 or I3− complexes within the MOF cavities, occurs when I2@UiO‐n samples are left in ambient light.
Conversion of I2 into I3− species trapped within UiO‐n. The adsorption of gaseous iodine in UiO‐n MOF‐like materials has been systematically studied by analyzing kinetic curves. They show the conversion of trapped I2 into anionic species I3−, which is enhanced by the existence of amino groups functionalizing the organic linkers.
This article reports a fourth-order continuous-time (CT) delta-sigma modulator (DSM) that features a single-amplifier biquad, a passive integrator, and an active integrator. This simplifies the ...circuit to only two op-amps in comparison to four power-hungry op-amps used in a conventional fourth-order DSM. In addition to improving the power consumption, the proposed design also has more relaxed requirements for the gain-bandwidth product and the loop gain. A 4-bit flash analog-to-digital converter (ADC) and two feedback digital-to-analog converters (DACs) are employed in this design to implement a fully integrated CT DSM. By incorporating the passive network in front of the last active integrator, this design gives a better attenuation at high frequency, which decreases the possibility of instability caused by out-of-band high-frequency signals. The proposed design has a measured bandwidth of 2 MHz with a power consumption of only around 3 mW. The effective number of bits (ENOB) of the proposed CT-DSM is approximately 12.7 bits with a peak signal-to-noise and distortion ratio (SNDR) around 78 dB, and it also exhibits a good Schreier figure of merit on the order of 166 dB compared to the existing state of the art.
In this brief, a tuneable low-power active bandpass filter (BPF) is designed for channel selection in TSMC's 65-nm CMOS technology. The proposed filter consists of two identical BPFs which are based ...on a gm-C topology, and can be controlled with a constant quality factor. The center frequency of this design can be changed to acquire a specific passband channel from 60 kHz to 2.5 MHz by adjusting the bias voltage in discrete increments, with an almost constant quality factor equal to 7.2. To validate the design, the integrated circuit and a test board are fabricated. Five passband channels are measured from the proposed design with a low power consumption equal to 68 <inline-formula> <tex-math notation="LaTeX">\mu \text{W} </tex-math></inline-formula>. The measured dynamic range is equal to 51.6 dB when the total harmonic distortion (THD) is equal to 1%. Hence, the proposed controllable channel selection filter shows an excellent performance as compared to existing work and offers a great potential for use applications with heterogeneous sensor nodes.
Animals often use sex pheromones for mate choice and reproduction. As for other signals, the genetic control of the emission and perception of sex pheromones must be tightly coadapted, and yet we ...still have no worked-out example of how these two aspects interact. Most models suggest that emission and perception rely on separate genetic control. We have identified a Drosophila melanogaster gene, desat1, that is involved in both the emission and the perception of sex pheromones. To explore the mechanism whereby these two aspects of communication interact, we investigated the relationship between the molecular structure, tissue-specific expression, and pheromonal phenotypes of desat1. We characterized the five desat1 transcripts—all of which yielded the same desaturase protein—and constructed transgenes with the different desat1 putative regulatory regions. Each region was used to target reporter transgenes with either (i) the fluorescent GFP marker to reveal desat1 tissue expression, or (ii) the desat1 RNAi sequence to determine the effects of genetic down-regulation on pheromonal phenotypes. We found that desat1 is expressed in a variety of neural and nonneural tissues, most of which are involved in reproductive functions. Our results suggest that distinct desat1 putative regulatory regions independently drive the expression in nonneural and in neural cells, such that the emission and perception of sex pheromones are precisely coordinated in this species.
This article analyzes the effects of key physical oceanographic conditions on underwater propagation in a shallow water environment. Signals at 2 kHz were transmitted and received over ranges of ...1-10 km, and the variability in the sound-speed profile, bathymetry, position of the instruments, and sea surface roughness was measured and the uncertainty on each parameter was estimated. The acoustic channel characteristics, including the transmission loss, delay spread, and coherence time, were calculated between a moored five-element vertical line array and a vessel deployed source. The measurement results were modeled using a Bellhop's ray tracing algorithm. The sensitivity of the simulator output was evaluated as a function of the environmental conditions, and the observed variability in the transmission loss was reproduced by varying the input parameters to the model within the observed and estimated bounds. The relative importance of the physical properties of the environment in terms of their impact on the acoustic channel is determined through a comparison of modeled and measured transmission loss variability.
In this work, a hardware-in-the-loop (HIL) simulator is designed to diagnose the behavior of an autonomous sailboat as it navigates between waypoints. At its core, the HIL simulator includes the ...sailboat pilot on an embedded system. The sensor data input to the embedded system is fed by a navigation simulator that takes into account the different forces on the sailboat due to the wind, waves and current conditions. The HIL simulator is then tested for a navigation route from sea trials published in 2014, and the behavior of the automated pilot is compared to its behavior when the vessel is driven by a crew. As demonstrated, the automated system can outperform the man-operated vessel. The tool is also used to diagnose weaknesses in the sailboat autopilot algorithm that can be improved in the future.
To develop and reproduce, animals need long-chain MUFAs and PUFAs. Although some unsaturated FAs (UFAs) can be synthesized by the organism, others must be provided by the diet. The gene, desat1, ...involved in Drosophila melanogaster UFA metabolism, is necessary for both larval development and for adult sex pheromone communication. We first characterized desat1 expression in larval tissues. Then, we found that larvae in which desat1 expression was knocked down throughout development died during the larval stages when raised on standard food. By contrast pure MUFAs or PUFAs, but not saturated FAs, added to the larval diet rescued animals to adulthood with the best effect being obtained with oleic acid (C18:1). Male and female mating behavior and fertility were affected very differently by preimaginal UFA-rich diet. Adult diet also strongly influenced several aspects of reproduction: flies raised on a C18:1-rich diet showed increased mating performance compared with flies raised on standard adult diet. Therefore, both larval and adult desat1 expression control sex-specific mating signals. A similar nutrigenetics approach may be useful in other metabolic mutants to uncover cryptic effects otherwise masked by severe developmental defects.
Over the past decade, interest in autonomous vessels significantly increased as the technology improved, especially in the automotive industry. Unlike cars, ships travel in a wild environment and ...maritime lanes are not limited by white lines. This makes the design of fully autonomous vessels even more challenging. Additionally, the need to reduce greenhouse gas emissions led to a renewed interest in wind propulsion. Sailboats have several advantages, such as full energy autonomy and a limited environmental impact. The Microtransat Challenge, which consists of crossing the Atlantic Ocean, is a tremendous test field. This paper describes, within that frame, a design procedure for the development of a robust fully autonomous sailboat to be deployed for long-term missions. In this paper, the mechanical and electronic design strategies are presented. A focus is on reliability and power management. Moreover, a test procedure for validating each design increment is described as well as a path plan that considers the risk of collision and weather routing with wind and currents. The Microtransat remains a challenge that no autonomous ship has ever succeeded (and has been completed by a single unmanned vessel, SB Met in 2018). However, the results by Breizh Tigresse and Sealeon in 2015 and 2018 made a step forward in terms of time and distance. They are presented and analyzed in this work.
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