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[IEEE 2018 International Symposium on Networks, Computers and Communications (ISNCC) - Rome (2018.6.19-2018.6.21)] 2018 International Symposium on Networks, Computers and Communications (ISNCC) - Design of a Photoconductive Antenna for Pulsed-Terahertz Spectroscopy with Polarization Diversity
摘要： In the present paper, a photoconductive antenna is designed to work as both pulse-terahertz emitter and receiver. The proposed two-port antenna benefits from polarization diversity with high sensitivity of polarization detection. The antenna electrodes consist of three arms and two gaps that can be excited by laser illumination. An 800 nm wavelength laser beam with output power of 80 mW, 100 MHz repetition rate, and 100 fs laser pulse duration is considered as optical excitation. Each port stimulates a pulse that its polarization is orthogonal to that of the other one according to their arrangement. Along with GaAs as photoconductive substrate beneath the antenna electrodes, an anti-reflection coating of Taconic RF-35 is used for depreciating unwanted terahertz echoes. The simulated results clarify that the proposed antenna shows polarization diversity and also, proper broadband behavior.
关键词： spectroscopy,polarization diversity,pulsed terahertz,photoconductive antenna
更新于2025-09-23 15:23:52
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Broadband simultaneously RHCP-LHCP radiating microstrip fed rectangular slot antenna for polarization diversity applications
摘要： In this article, for the first time, an antenna that can radiate LHCP and RHCP waves simultaneously is presented. The antenna enables simultaneous transmission of both right-handed (RH) and left-handed (LH) circular polarized (CP) waves separately over an elevation range from -45 to 45 degrees from the zenith. The simultaneous radiation of dual sense CP in the different spatial directions enables the antenna to act as polarization diversity transmitter. The mechanism of virtual sequential rotation of magnetic currents inside the different parts of the slot, excited with uniform phase fields results in dual CP generation. The uniform phase orthogonal fields are generated in the different parts of the slot essentially by exciting the full wavelength rectangular slot loaded with grounded stubs, symmetrically, with a shorted microstrip line. The final design of the slot antenna arrived with a rigorous parametric study on different dimensional parameters of slot and grounded stub. The measured impedance bandwidth of 22.5% centered around 7 GHz and axial ratio bandwidth of 19% is achieved. An overlapping bandwidth of 17% is achieved where both matching and AR are very good. The measured isolation between the RHCP and LHCP in the above-mentioned elevation ranges is maintained above 10 dB. The simulated and experimental results are matching very well.
关键词： right-handed CP,magnetic currents,Mobile satellite communications,axial ratio,rectangular slot,polarization diversity,left-handed CP,simultaneous dual CP
更新于2025-09-23 15:23:52
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Structural diversity, magnetic properties, and luminescent sensing of four coordination polymers based on 6-(3,5-dicarboxylphenyl)nicotinic acid
摘要： Four coordination polymers (CPs), namely, [Ni(HDNA)(bibp)(H2O)]n (1), [Co(HDNA)(bibp)]n (2), {[Co(HDNA)(bibp)]·H2O}n (3) and {[Zn(HDNA)(bibp)]·H2O}n (4), have been synthesized from the mixed-ligand strategy of 6-(3,5-dicarboxylphenyl)nicotinic acid (H3DNA) and 4,4′-bis(benzimidazo-1-ly)benzene (bibp). Structural analyses revealed that four CPs all feature 2D sheets with diverse nets from {44.62}-sql net (1), {Co2(COO)2} SBUs based {44.62}-sql net (2), to 4-connected {65.8} sheet (3 & 4). Besides, the temperature-dependent magnetic susceptibilities of CPs 1-3 were investigated. And the luminescent sensing indicated CP 4 is a good bifunctional sensor for Fe3+ and Cr2O7 2- ions.
关键词： Structural diversity,Coordination polymers,Luminescent sensing,Magnetic property,Polycarboxylic acid ligand
更新于2025-09-23 15:23:52
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Functional Diversity in the Retina Improves the Population Code
摘要： Within a given brain region, individual neurons exhibit a wide variety of different feature selectivities. Here, we investigated the impact of this extensive functional diversity on the population neural code. Our approach was to build optimal decoders to discriminate among stimuli using the spiking output of a real, measured neural population and compare its performance against a matched, homogeneous neural population with the same number of cells and spikes. Analyzing large populations of retinal ganglion cells, we found that the real, heterogeneous population can yield a discrimination error lower than the homogeneous population by several orders of magnitude and consequently can encode much more visual information. This effect increases with population size and with graded degrees of heterogeneity. We complemented these results with an analysis of coding based on the Chernoff distance, as well as derivations of inequalities on coding in certain limits, from which we can conclude that the beneficial effect of heterogeneity occurs over a broad set of conditions. Together, our results indicate that the presence of functional diversity in neural populations can enhance their coding fidelity appreciably. A noteworthy outcome of our study is that this effect can be extremely strong and should be taken into account when investigating design principles for neural circuits.
关键词： retina,neural coding,discrimination error,mutual information,functional diversity,Chernoff distance,population code,heterogeneity
更新于2025-09-23 15:23:52
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[IEEE 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Varna (2018.9.20-2018.9.22)] 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Investigation of Reliability of Diversity Systems Through Stress-Strength Model Analysis
摘要： Paper concerns a problem of reliability indexes calculation of two channel homogeneous and diversity system. Using SSM it is easy to determine the probability of Common Cause Failures (CCF) and other parameters of investigated redundant systems. Here is used a complex approach with Multi-Factor Stress-Strength Model (MFSSM). The obtained analytical formulas are verificated via simulation.
关键词： diversity,common cause failures,stress-strength model,dependability
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Improved Differential Evolution with Parameter Adaption Based on Population Diversity
摘要： The differential evolution algorithm is an important branch of the bionic intelligent computation, which uses the Darwinian population's evolutionary principle: survival of the fittest and survival of the fittest. Due to the simple implement and few parameters, many researchers have invested into the study of the algorithm and proposed a large number of differential evolution variants. For the existing differential evolution algorithm, once the size of the population is determined, the size of the search range is fixed. Based on the global diversity of population, we focus on controlling the value of the search parameters p. In the proposal, after normalizing the population diversity, each individual will select its unique search scope according to the diversity conditions. Therefore, the proposed method can balance between the global search and the local search. According to our extensive experimental results on various benchmark functions, the proposed method outperform other compared advanced algorithms.
关键词： population diversity,SHADE,differential evolution
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Capabilities of Lidar- and Satellite Data in Assessing the Drivers of Avian Diversity in a Fragmented Landscape
摘要： In modern landscapes, small habitat patches such as woodlands isolated in an agricultural matrix, can be important refuges for wildlife. However, their value as habitat may be compromised by their size and thus knowledge of how habitat structure influences habitat quality is vital to maximize species diversity. This study examined the factors driving avian diversity in four small woods in an agricultural landscape, and how accurately remote sensing (RS) metrics were able to quantify this. Linear mixed-effect models were used to combine annual breeding bird census data with data of habitat structure from satellite images and airborne lidar. The aims were firstly to examine the drivers of bird diversity, and secondly to reveal the strengths and weaknesses of the compared RS datasets in quantifying them. The results showed that, at first, bird diversity increased significantly towards the edges, being driven in part by vegetation structure. The amount of understorey vegetation was the most significant driver of diversity, due to which lidar-based models outperformed satellite-based ones. In general, lidar metrics correlated strongly with bird diversity, but such relationships were not discovered with satellite image metrics. The results indicate that the drivers of diversity, especially in fragmented woodlands may be too fine-scaled to be studied without sufficient consideration of the structural component of vegetation, which was proven to be attainable from lidar data.
关键词： habitat,fragmentation,lidar,bird diversity,satellite,landscape ecology
更新于2025-09-23 15:22:29
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Uncoded M-ary quadrature amplitude modulation space-time labeling diversity with three transmit antennas
摘要： Uncoded space‐time labeling diversity (USTLD) is a recent scheme that improves the error performance of space‐time block–coded wireless communication links. However, the existing space‐time labeling diversity technique used in USTLD only employs two transmit antennas. To further improve error performance in USTLD systems, this paper investigates USTLD systems with three transmit antennas. A heuristic approach is proposed to design the second and third mappers. Simulation results show superior error performance compared with the existing two transmit antenna USTLD. Furthermore, an analytical expression for a tight bound of the average bit error probability of the proposed system with three transmit antennas is derived. Moreover, complexity reduction analysis of the low‐complexity (LC) detector is proposed. It is shown that the proposed LC algorithm achieves near‐maximum likelihood detection accuracy, while reducing complexity by 51% and 96.5% for 16QAM and 64QAM, respectively.
关键词： heuristic algorithm,labeling diversity,near‐ML detection,labeling mapper
更新于2025-09-23 15:21:01
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[IEEE 2019 European Space Power Conference (ESPC) - Juan-les-Pins, France (2019.9.30-2019.10.4)] 2019 European Space Power Conference (ESPC) - Potential of the three-terminal heterojunction bipolar transistor solar cell for space applications
摘要： Cooperative communication suffers from multiplexing loss and low spectral efficiency due to the half duplex constraint of relays. To improve the multiplexing gain, successive relaying, which allows concurrent transmission of the source and relays, has been proposed. However, the severe inter-relay interference becomes a key challenge. In this paper, we propose a channel aware successive relaying protocol, also referred to as CAO-SIR, which is capable of thoroughly mitigating inter-relay interference by carefully adapting relays’ transmission order and rate. In particular, a relay having a poorer link to the source is scheduled first to forward a message, the data rate of which is adapted to the link quality of the source-relay and relay-destination channels. By this means, each relay may decode the messages intended for the preceding relays, and then cancel these relays’ interference in a low complexity which is equal to that of Decision Feedback Equalizer (DFE). To further optimize and analyze CAO-SIR, we present its equivalent parallel relay channel model, based upon which the adaptive relay selection and power allocation schemes are proposed. By employing M half duplex relays, CAO-SIR is capable of achieving an diversity-multiplexing tradeoff (DMT) given by 1 ? M +2 and r denote the diversity and multiplexing gains, respectively. Its DMT asymptotically approaches the DMT upper bound achieved by (M + 1) × 1 MISO systems or M full duplex relays, when M is large.
关键词： diversity-multiplexing tradeoff,rate adaptation,Successive relaying,relay selection,interference cancellation,power allocation,water filling,opportunistic communications,relay ordering
更新于2025-09-23 15:19:57
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Asymptotic Performance of Generalized Transmit Laser Selection Over Lognormal Turbulence Channels
摘要： In free space optical communication systems, transmit laser selection (TLS) has been proposed as an efficient fading-mitigation technique over turbulence channels. In TLS, the transmitter is equipped with a number of laser sources and the best laser source is selected for transmission. In practice, feedback error or outdated selection due to temporal changes in the channel may result in selecting another source rather than the best one. In this paper, we consider a FSOC system with generalized TLS (GTLS) where the nth best laser is selected among the available N lasers. Under the assumption of lognormal turbulence channels in addition to pointing errors, we derive a closed-form expression for asymptotic bit error rate. We use our derived closed-form expression to determine the diversity gains. We finally present simulation results to corroborate our analytical findings.
关键词： Free space optical communication,diversity order,lognormal fading,generalized transmit laser selection
更新于2025-09-23 15:19:57