Unambiguous Target Research Articles

Efficient Transceiving Search Scheme and Implementation Method for Collocated Distributed Coherent Aperture Radar via Grating Lobes Exploitation

Distributed coherent aperture radar (DCAR) can realize high-precision long-range detection because of its excellent angular resolution. However, it is accompanied by a low search efficiency problem caused by the narrow main lobe and the angular ambiguity problem stemming from the high grating lobes. By simultaneously utilizing multiple grating lobes, we propose an effective search method and pertinent unambiguous signal processing algorithms to address the issue of using collocated DCAR for unambiguous target search. We investigate the beam migration of a grating lobe-irradiated target at various frequencies in order to carry out the multi-frequency coherent integration of the suggested search method in DCAR. In order to address the issue of using multiple beam lobes to simultaneously detect multiple targets, we also take into account the scenario of multiple targets and introduce the multiple hypothesis method to solve the problem. The DCAR search efficiency can be improved by tens of times through grating lobes exploitation, which makes use of DCAR to make the searches feasible. We also improved the performance of multi-frequency DOA ambiguity solving compared to existing algorithms with the sliding window clustering scheme. The viability of using grating lobes for the DCAR target searching and detection is shown in simulations. The experiments confirm the performance enhancement of multi-frequency coherent integration for parameter estimation.

Connecting Material Properties and Redox Flow Cell Cycling Performance through Zero-Dimensional Models

Improvements in redox flow battery (RFB) performance and durability can be achieved through the development of new active materials, electrolytes, and membranes. While a rich design space exists for emerging materials, complex tradeoffs challenge the articulation of unambiguous target criteria, as the relationships between component selection and cycling performance are multifaceted. Here, we derive zero-dimensional, analytical expressions for mass balances and cell voltages under galvanostatic cycling, enabling direct connections between material/electrolyte properties, cell operating conditions, and resulting performance metrics (e.g., energy efficiency, capacity fade). To demonstrate the utility of this modeling framework, we highlight several considerations for RFB design, including upper bound estimation, active species decay, and membrane/separator conductivity-selectivity tradeoffs. We also discuss modalities for extending this framework to incorporate kinetic losses, distributed ohmic losses, and multiple spatial domains. Importantly, because the mass balances are solved analytically, hundreds of cycles can be simulated in seconds, potentially facilitating detailed parametric sweeps, system optimization, and parameter estimation from cycling experiments. More broadly, this approach provides a means for assessing the impact of cell components that simultaneously influence multiple performance-defining processes, aiding in the elucidation of key descriptors and the identification of favorable materials combinations for specific applications.

Super Resolution Wide Aperture Automotive Radar

State-of-the-art automotive radars have an angular resolution of 1°, which is insufficient for estimating the objects shape and boundaries at long distance. In this paper, we design a novel automotive radar with 1m aperture, which is an order of magnitude larger aperture than state-of-the-art automotive radars, and thus achieves super high angular resolution of 0.1°. The radar is designed to overcomes the major technical challenges of a wide aperture radar, which are: non-robust phase coherency over a wide aperture, spanning a wide aperture with sparse antenna elements, simultaneous non-interfering transmissions from a relatively large number of transmit antennas with unambiguous target speed estimation, and high complexity of near-field beamforming. We demonstrate the super high resolution performance of the radar in automotive scenarios, and show that it attains comparable results to a high resolution LIDAR at short range, and outperforms the LIDAR at long ranges. The wide aperture radar has the potential to enable autonomous driving at higher speed, and also to increase the operation of autonomous driving to more regions and climates.

Subarray-Based Frequency Diverse Array for Target Range-Angle Localization With Monopulse Processing

Frequency diverse array (FDA) can offer new degrees-of-freedom, but the target localization of basic FDA is fundamentally limited by the range-angle-coupled and range-periodic peaks of beampattern. In this paper, we propose a localization system with the combination of subarray-based FDA and full-band FDA, as the transmitter and the receiver, respectively. The transmit and receive beampatterns are both decoupled in range and angle domains. Target range-angle localization is achieved by two steps. First, using the outputs of subarrays, we solve the range ambiguity and obtain a coarse location. Second, the monopulse processing of range-angle localization is developed for the proposed system by taking the coarse location as the receiving beam pointing. The localization performance is also analyzed in Cramer-Rao lower bound, computational complexity, and output signal to interference-plus-noise ratio. Several simulation results demonstrate that unambiguous target range-angle localization can be achieved with a low computational cost by the proposed method.

Complete, Programmable Decoding of Oxidized 5-Methylcytosine Nucleobases in DNA by Chemoselective Blockage of Universal Transcription-Activator-Like Effector Repeats.

5-Methylcytosine (5mC) and its oxidized derivatives are regulatory elements of mammalian genomes involved in development and disease. These nucleobases do not selectively modulate Watson-Crick pairing, preventing their programmable targeting and analysis by traditional hybridization probes. Transcription-activator-like effectors (TALEs) can be engineered for use as programmable probes with epigenetic nucleobase selectivity. However, only partial selectivities for oxidized 5mC have been achieved so far, preventing unambiguous target binding. We overcome this limitation by destroying and re-inducing nucleobase selectivity in TALEs via protein engineering and chemoselective nucleobase blocking. We engineer cavities in TALE repeats and identify a cavity that accommodates all eight human DNA nucleobases. We then introduce substituents with varying size, flexibility, and branching degree at each oxidized 5mC. Depending on the nucleobase, substituents with distinct properties effectively block TALE-binding and induce full nucleobase selectivity in the universal repeat. Successful transfer to affinity enrichment in a human genome background indicates that this approach enables the fully selective detection of each oxidized 5mC in complex DNA by programmable probes.

Identifying target reference points for harvesting assessment-limited wildlife populations: a case study.

Identifying appropriate strategies for sustainable harvest is a challenge for many terrestrial vertebrate species because of uncertain system dynamics, limited data to inform population models, and potentially conflicting objectives that seek to harvest and maintain populations at desirable levels. The absence of monitoring and assessment infrastructure needed to regularly estimate abundance accentuates this challenge for many species, and limits application of rigorous state-dependent frameworks for decision making that are commonly advocated in natural resource management. Reference points, which define management targets or triggers for changing management, are often used to guide decision-making, but suffer from ambiguity when developed without explicit consideration of uncertainty or trade-offs among competing objectives. We describe an approach for developing unambiguous target reference points for assessment-limited species using structured decision making, and demonstrate the approach to develop target harvest rates for management of fall Wild Turkey (Meleagris gallopavo) harvests in the face of uncertain population and harvest dynamics. We use simulation and decision analyses to identify harvest rates that are optimal for accomplishing explicit management objectives in the face of uncertainty, and harvest rates with robust performance over broad regions of the demographic and harvest model parameter space. We demonstrate that population and harvest parameters commonly uncertain to wildlife managers interact to determine appropriate target harvest rates for Wild Turkeys, and that formally acknowledging a range of plausible values for structurally uncertain parameters results in more conservative target reference points than suggested by previously published studies. The structured decision making framework described here provides a natural conceptual and quantitative framework for extending our approach to develop unambiguous harvest targets for other assessment-limited wildlife populations while formally acknowledging structural uncertainty in system dynamics.

Ambiguities in target motion estimation for general SAR measurements

This study investigates the ability to invert synthetic aperture radar (SAR) measurement data in order to obtain unique estimates of the underlying motion parameters of targets within the imaged scene. In particular, this investigation reveals that ambiguities exist in estimating the kinematics parameters of surface targets for cases of general bistatic SAR collections. Specifically, the current study presents a detailed methodology for constructing any number of alternate target trajectories which yield the same set of SAR measurements as that corresponding to the true target motion. Additionally, the target trajectory ambiguities of the current investigation are shown to remain even if the radar system obtains bistatic range-rate or Doppler measurements. Unambiguous kinematics estimates can be obtained only through additional constraints, as with assumptions that a given surface target lies on the one-dimensional locus of a road. Thus, the ability to localise and estimate unambiguous target motion parameters relies on the energy intensity patterns of the transmission and reception beams of the radar system. Overall, the current analysis provides a simple, and yet powerful, exposition of the nature of target trajectory ambiguities in monostatic and bistatic SAR imagery.

Optional opacity: A syntactically-based analysis of early Hebrew verb morphology

The study aims to account for the distribution of finite versus non-finite verbs during a developmental period when children use both types of verb forms in contexts requiring finiteness. To meet this goal, longitudinal samples from three Hebrew-acquiring children (aged 1;4–2;6) are examined from the onset of verb production and across the ‘optional’ period in which finite and non-finite verbs occur side by side. Each verb-containing utterance is specified for structural transparency (whether the verb has a clearly unambiguous target) and for additional clausal constituents. Analysis reveals that during the ‘optional’ period non-transparent verb forms favor elaborated syntactic environments (i.e., accompanied by objects and/or adverbs) at significantly higher rates than their transparent counterparts. These morpho-syntactic patterns in children’s verb usage provide a line of explanation for the distribution of inflected versus non-inflected forms, and highlight the role of between-domain inter-relations in language acquisition.

An evaluation of the effectiveness of Comic Strip Conversations in promoting the inclusion of young people with autism spectrum disorder in secondary schools

Objectives:Comic Strip Conversations (CSCs; ) can be used to improve the social skills of individuals on the autism spectrum as well as pupils with other learning and/or speech difficulties. This study aimed to evaluate this intervention to improve specific problematic target behaviours of eleven to fourteen year old pupils with Autism Spectrum Disorder (ASD), to ascertain whether or not including a written (visual) action plan or a discussion about actions (auditory action plan) would have an impact and to find out whether more effective action plans matched participants’ visual and verbal skill profiles.Methods:A total of eight participants ranging from eleven to fourteen years of age received the intervention in school. Cognitive assessments were conducted to assess verbal and non-verbal functioning. A multiple baseline design across behaviours was implemented. Structured observations were conducted in order to determine whether or not the CSC intervention had an impact on target behaviours.Results:The percentage of data points exceeding the median (PEM) of the baseline phase and Tau-U analyses were calculated from the observational data. Combined with visual inspection of graphs, the intervention was found to be moderately to highly effective at reducing/improving target behaviours in seven out of eight participants.Conclusion:Although there was no general association between the type of action plan (visual or verbal) and outcome, the more successful action plans included highly specified, unambiguous target behaviours, realistic and implementable strategies/solutions, regular reviews of the CSC and a mode of presentation that matched the participants’ skill preferences.

Range resolved lidar for long distance ranging with sub-millimeter resolution

A lidar technique employing temporally stretched, frequency chirped pulses from a 20 MHz mode locked laser is presented. Sub-millimeter resolution at a target range of 10.1 km (in fiber) is observed. A pulse tagging scheme based on phase modulation is demonstrated for range resolved measurements. A carrier to noise ratio of 30 dB is observed at an unambiguous target distance of 30 meters in fiber.

Summing it up: Semantic activation processes in the two hemispheres as revealed by event-related potentials

The coarse coding hypothesis suggests that semantic activation is broader in the right hemisphere, affording it an advantage over the left hemisphere for the activation of distantly related concepts or multiple meanings of lexically ambiguous words. Behavioral studies investigating coarse coding have yielded mixed results, perhaps in part because such measures sum across multiple processing stages. To more directly tap into the semantic activation processes that are the focus of the coarse coding hypothesis, the current study combined a visual half-field summation-priming paradigm with the measurement of event-related potentials (ERPs). Two primes converged onto a lateralized, unambiguous target (e.g., lion–stripes–tiger) or diverged onto different meanings of a lateralized, ambiguous target (e.g., kidney–piano–organ); in both cases, the primes were related to one another only through the target. In two experiments, participants either made lexical decisions to the targets or made a semantic-relatedness judgment between primes and target. Priming was measured as reductions in the amplitude of the N400, an ERP component that has been specifically linked to meaning activation and that showed semantic-level priming patterns in both of the tasks used in the present study. Counter to the predictions of the coarse coding hypothesis, equivalent N400 summation priming was observed for targets in the two visual fields, in both types of triplets and in both experiments. Thus, the current results fail to support the hypothesis that semantic activation patterns differ in the two hemispheres and point, instead, to other sources for observed asymmetries in verbal processing.

Lexical access and selection of contextually appropriate meaning for ambiguous words

To clarify the neural mechanisms of lexical access and selection of contextually appropriate meanings for ambiguous words, we investigated the spatio-temporal characteristics of neural activities during silent reading and semantic judgment of lexically ambiguous or unambiguous target words that were preceded by semantically related or unrelated words by using magnetoencephalography. The left posterior superior temporal/inferior parietal area and the left anterior middle/inferior temporal area consistently showed a clear context effect, regardless of the ambiguity: the activities for related words were weaker than those for unrelated words. The activities in the left inferior frontal cortex, in contrast, were influenced by ambiguities. From ∼200 to 300 ms, the activities in the left anterior inferior frontal cortex (aIFC) were stronger for ambiguous words than for unambiguous words, regardless of context. The stronger activities in the left aIFC, reflecting an increase in controlled semantic retrieval, indicate that multiple meanings for lexically ambiguous words are accessed irrespective of context. At ∼400 ms, the left posterior inferior frontal cortex (pIFC) showed a clear context effect for unambiguous words but not for ambiguous ones. In addition, the activation in the left pIFC was stronger for related ambiguous words than for related unambiguous ones. These results suggest that in ambiguous words, not only contextually appropriate meanings but also two or more inappropriate meanings would be semantically integrated with a context. We conclude that the left IFC plays an important role in selecting an appropriate meaning from multiple alternatives after the integration of contextual information.

Choosing appropriate temporal and spatial scales for ecological restoration.

Classic ecological restoration seems tacitly to have taken the Clementsian "balance of nature" paradigm for granted: plant succession terminates in a climax community which remains at equilibrium until exogenously disturbed after which the process of succession is restarted until the climax is reached. Human disturbance is regarded as unnatural and to have commenced in the Western Hemisphere at the time of European incursion. Classic ecological restoration thus has a clear and unambiguous target and may be conceived as aiming to foreshorten the natural processes that would eventually lead to the climax of a given site, which may be determined by its state at "settlement". According to the new "flux of nature" paradigm in ecology a given site has no telos and is constantly changing. Human disturbance is ubiquitous and long-standing, and at certain spatial and temporal scales is "incorporated". Any moment in the past 10,000 years that may be selected as a benchmark for restoration efforts thus appears to be arbitrary. Two prominent conservationists have therefore suggested that the ecological conditions in North America at the Pleistocene-Holocene boundary, prior to the anthropogenic extinction of the Pleistocene megafauna, be the target for ecological restoration. That suggestion explicitly assumes evolutionary temporal scales and continental spatial scales as the appropriate frame of reference for ecological restoration. However, ecological restoration should be framed in ecological spatio-temporal scales, which may be defined temporally in reference to ecological processes such as disturbance regimes and spatially in reference to ecological units such as landscapes, ecosystems, and biological provinces. Ecological spatio-temporal scales are also useful in achieving a scientifically defensible distinction between native and exotic species, which plays so central a role in the practice of ecological restoration and the conservation of biodiversity. Because post-settlement human disturbances have exceeded the limits of such scales, settlement conditions can be justified scientifically as appropriate targets of restoration efforts without recourse to obsolete teleological concepts of equilibria and without ignoring the presence and ecological influence of indigenous peoples.

Display cloning: functional identification of natural product receptors using cDNA-phage display.

The identification of cellular targets has traditionally been the starting point for natural product mode of action studies and has led to the understanding of many biological processes. Conventional experimental approaches have depended on cell-based screening and/or affinity chromatography. Although both of these techniques aid in the discovery of protein cellular targets, a method that couples protein identification with gene isolation would be extremely valuable. A procedure for the direct cloning of cellular proteins, based on their affinity for natural products, using cDNA phage display has been developed. The technique is referred to as display cloning because it involves the cloning of proteins displayed on the surface of a bacteriophage particle. The approach has been established by isolating a full-length gene clone of FKBP12 (FK506-binding protein) from a human brain cDNA library using a biotinylated FK506 probe molecule. During the affinity selection, the FKBP12 gene emerged as the dominant library member and was the only sequence identified after the second round of selection. The development of display cloning greatly facilitates the investigation of ligand-receptor interaction biology and natural product mode of action studies. This procedure utilizes heterologous protein display on infectious phage, which allows the amplification and repeated selection of putative sequences, leading to unambiguous target identification. In addition, the direct connection of a functional protein to its gene sequence eliminates the subsequent cloning step required with tissue homogenate or cell lysate affinity methods, allowing direct isolation of an expressible gene sequence.

Semantic context and figure-ground organization

The semantic-priming paradigm was used to investigate the effect of semantic context on the latency to identify visually ambiguous and unambiguous targets. Ambiguous targets had reversible figure-ground organizations analogous to Rubin's vase-profiles picture in which the figural vase is shaped by the same contour that, if reassigned, shapes two figural profiles. The two organizations of the ambiguous targets were either a series of black irregular shapes or a familiar word in white letters; subjects were required to achieve the latter organization. Unambiguous target words were not reversible. Related primes, unlike unrelated primes, facilitated the identification of both types of target; but the magnitude of facilitation was greater for ambiguous targets. The results demonstrate that semantic context influences the speed of figure-ground organization and add perceptual ambiguity to the target manipulations that interact with context to affect encoding.

Inverse acoustic problems in the resonance scattering regime

Solving an inverse scattering problem here means the extraction of physical (viz., composition and shape) information from the active echo returned to an underwater elastic target. This is the general area of target identification. In this sense, solving inverse scattering problems is relatively simple (!) in the low or high spectral regions because there a number of simplifying approximations may apply. However, for the intermediate or resonance region of all scatterers, the above approximations do not hold, and exact solutions or novel types of approximations are necessary, making the actual inversions of scattered waveforms extremely hard. A certain level of success has been achieved by exploiting the presence of certain resonance features that manifest themselves in the resonance region of the scattering cross sections (SCS) of submerged elastic targets. Examples of how and how well one can extract identifying sets of resonance features from an echo have been recently overviewed [G. Gaunaurd, J. Acoust. Soc. Am. Suppl. 1 84, S168 (1988)]. Although the main interest over the years has been the isolation of the resonance features in the SCS either by theoretical (viz., the background subtraction) and/or experimental (viz., samplings of echoes in their tail portions) means, little has been said about what to do with them, once isolated. This paper will show (idealized) examples illustrating how these resonance features can be actually used for unambiguous target characterization.

Event-related potential indices of ambiguous sentence processing

An event-related potential (ERP) probe was used to examine various models of ambiguous sentence processing. ERPs to light flashes were recorded during and immediately after auditorily presented ambiguous and unambiguous target sentences. Each target sentence was preceded by either a relevant or a neutral context sentence. Principal component analyses of the ERPs indicated that although certain components varied as a function of ambiguity, none of the components varied as a function of preceding context. These findings provided some support for a postdecision model of ambiguity processing which suggests that both meanings of an ambiguity are always processed, even when prior disambiguating context is available.

Price Regulation Under Uncertainty in an Asymmetric Decision Environment

A regulated firm that can make decisions both before and after uncertainty is resolved with respect to input use cannot be led to competitive solutions by regulatory price ceilings. Whether those ceilings are imposed before or after the resolution of uncertainty, they present incentives for undercapitalized production, contrary to usual AJ assertions. Under these conditions the Fair Return objective is neither a sufficient nor an unambiguous regulatory target.

AIR TRAJECTORIES AND TURBULENCE STATISTICS FROM WEATHER RADAR USING TETROONS AND RADAR TRANSPONDERS

Abstract An experiment was carried out to determine the feasibility of utilizing weather radar (WSR-57) to obtain air trajectories over tens of miles at altitudes less than 5,000 ft. above the ground. Five constant volume balloons (tetroons) were released each carrying a lightweight (about 150 gm.) transponder which upon being interrogated by the WSR-57 radar would transmit an identifying signal. All flights were successful and the transponder signals provided positive, unambiguous target identification at ranges and altitudes where the ground clutter made direct reflective positioning impossible. Although the purpose of the experiment was to test the tracking system, data of particular interest were obtained from the simultaneous release of a pair of tetroons which were tracked for more than 2 hours to beyond 20 mi. Analysis of these two flights provided values of the relative dispersion Ȳ2 proportional to t3 and larger, as well as showing negative separation rates. These flights also provided estimates ...