Typically, weed density is used to predict weed-induced yield loss, as it is easy and quick to quantify, even though it does not account for weed size and time of emergence relative to the crop. Weed-crop leaf area relations, while more difficult to measure, inherently account for differences in plant size, representing weed-crop interference more accurately than weed density alone. Unmanned aerial systems (UAS) may allow for efficient quantification of weed and crop leaf cover over a large scale. It was hypothesized that UAS imagery could be used to predict maize yield loss based on weed-crop leaf cover ratios. A yield loss model for maize (Zea mays L.) was evaluated for accuracy using 15- and 30-m altitude aerial RGB and four-band multispectral imagery collected at four North Carolina locations. The model consistently over and underpredicted yield loss when observed yield loss was less than and greater than 3000 kg ha-1, respectively. Altitude and sensor type did not influence the accuracy of the prediction. A correction for the differences between predicted and observed yield loss was incorporated into the linear model to improve overall precision. The correction resulted in r2 increasing from 0.17 to 0.97 and a reduction in RMSE from 705 kg ha-1 to 219 kg ha-1. The results indicated that UAS images can be used to develop predictive models for weed-induced yield loss prior to canopy closure, making it possible for growers to plan production and financial decisions before the end of the growing season.

This paper presents a comprehensive analysis of interference events in automotive scenarios based on radar systems equipped with communication-assisted chirp sequence (CaCS). First, it examines the impact of interference on radar and communication functionalities in CaCS systems according to the orientation of the investigated nodes. For this purpose, a graph-based approach is employed with MATLAB simulations to illustrate the potential occurrence of interference on the graph for communication functionality compared with their counterparts on radar. Second, the paper delves into the impact of interference on the synchronization between two communicating CaCS nodes. It extends a previous study to match the frequency of current radar sensors, where chirp estimation, an adjusted version of the Schmidl & Cox algorithm, and correlation are adopted to synchronize the transmitter and receiver of two CaCS communicating nodes in the time-frequency plane. The proposed synchronization method is finally verified by measurements at ${79}\,\mathrm{GHz}$ with a system-on-chip, where the resulting correlation metric and mean square error are illustrated as validation factors.

The presented research investigates the impact of interference on the performance of aircraft Global Navigation Satellite System (GNSS) receivers with a specific focus on the behaviour of Automatic Dependent Surveillance-Broadcast (ADS-B) position quality indicators. Several experiments were performed with different aircraft types, such as Airbus, Boeing, Beechcraft King Air B350 or Tecnam, and using various intensities of GNSS jamming. The behaviour of various quality indicators, such as the Navigation Integrity Category, Navigation Accuracy Category, Source Integrity Level and System Design Assurance transmitted in different types of ADS-B messages, is analysed. We investigate not only situations where the quality indicators drop to zero, but also the complete evolution of the changes in the indicators as a function of the increasing power of the jamming signal. Based on the analysis of changes in the ADS-B quality indicators, the estimation of the most likely interference signal power required to discontinue the tracking of an already acquired GPS L1 Coarse/Acquisition signal is made. Additionally, the interference signal power to prevent re-acquisition is also estimated. The findings improve the understanding of interference effects and can support the development of robust interference mitigation techniques in aviation applications.

Furrow-irrigated rice (Oryza sativa L.) hectares are increasing in the Midsouth. The lack of sustained flooding creates a favorable environment for weed emergence and persistence, which makes Palmer amaranth (Amaranthus palmeri S. Watson) difficult to control throughout the growing season. The negative yield impacts associated with season-long A. palmeri interference in corn, cotton, and soybean have been evaluated. However, there is limited knowledge of the weed’s ability to influence rice grain yield. Research was initiated in 2022 and 2023 to determine the effect of A. palmeri time of emergence relative to rice on weed seed production and grain yield. Cotyledon stage A. palmeri plants were marked every seven days, beginning one week before rice emergence through four weeks after rice emergence. Amaranthus palmeri seed production decreased exponentially as emergence timing was delayed relative to rice, and seed production increased by 447 seed plant-1 for every one-gram increase in weed biomass. Without rice competition and from the earliest emergence timing, A.palmeri produced 540,000 seeds plant-1. Amaranthus palmeri that emerged one week before the crop had the greatest spatial influence on rice, with grain yield loss of 5% and 50% at a distance of 1.4 m and 0.40 m from the weed, respectively. As A. palmeri emergence was delayed, the area of influence decreased. However, A. palmeri plants emerging 3.5 weeks after rice emergence still negatively affected grain yield and produce sufficient seed to replenish the soil seedbank, potentially impacting long-term crop management decisions. These results show that the time of A. palmeri emergence is a crucial factor influencing rice grain yield and weed seed production, which can be used to determine the consequences of escapes in rice.

Dominant debates about China’s growing presence in the Pacific Islands – through infrastructure, aid, trade, and investment – suggest that Chinese material power directly translates to influence and effective interference in Pacific states’ domestic and foreign affairs. These perspectives fail to clarify the causal link between Chinese economic statecraft and Pacific governments’ alignment with Beijing’s interests. They also deny Pacific people agency, overlooking how power relations are mediated by Pacific state and non-state actors operating across complex political and socio-economic structures. We challenge such rationalist conceptualisations of Chinese power by developing a constructivist taxonomy of power as presence (dormant capability), influence (socialisation), and interference (incentives), and applying it to the Melanesian subregion. We argue that Chinese power is not merely material, causal, and unidirectional. Chinese power can also (re)shape the identities and interests of Pacific elites and publics in a constitutive manner, potentially aligning their ideas about substantive norms, rules, and practices guiding their foreign relations with Chinese ‘core interests’ and perspectives on regional and global politics.

Differences between native (L1) and non-native (L2) comprehension have been debated. This study explores whether a source of potential L1/L2 differences lies in susceptibility to memory-based interference during dependency formation. Interference effects are known to occur in sentences like The key to the cabinets were rusty, where ungrammaticality results from a number mismatch between the sentence subject and verb. Such sentences are sometimes misperceived as grammatical due to the presence of a number-matching “distractor” (“the cabinets”). Interference has been well-examined in a number agreement. However, whether and how forming thematic relations is susceptible to interference remains underexplored in L1 and L2 language comprehension. In six preregistered experiments, we investigated semantic interference in language comprehension and explored whether potential L1/L2 differences can be attributed to different degrees of susceptibility to interference. The results did not show that L2 speakers are more susceptible to interference than L1 speakers. Also, the observed interference patterns were only partially consistent with existing theories of memory retrieval during comprehension. We discuss how these theories may be reconciled with our findings and argue our results suggest that similar processes are involved in L1 and L2 subject-verb dependency formation.

Replacement series are used by researchers to understand how competition-related variables influence dynamics from the individual to the population and community levels, but this approach has been criticized because of inherent biases associated with plant size differences and density-dependent responses. The use of functional densities instead of demographic densities was proposed to minimize those biases. This work explored three models to determine reference densities for replacement series experiments based on (1) maximum biomass, (2) biomass at onset of diminishing returns (i.e., inflection point), and (3) nitrogen (N)-uptake equivalency. Replacement series experiments were conducted using redroot pigweed (Amaranthus hybridus L.):maize (Zea mays L.) and giant foxtail (Setaria faberi Herrm.):maize proportions of 1:0, 0.75:0.25, 0.5:0.5, 0.25:0.75, and 0:1. The monoculture density for each species was established according to the three models. Density selection criteria resulted in major differences in competitive interactions between species. The use of functional densities at which the biomass accumulation inflection point for the smaller species allowed both species to exhibit either increases or decreases in biomass production depending on competitive interactions for all interspecific mixtures. Conversely, the maximum biomass model favored the larger species, almost completely inhibiting the growth of the smaller species, which resulted in a poor characterization of competitive responses of the smaller species. The N uptake equivalency model resulted in interactions closer to the predicted neutral competition. The model based on the biomass accumulation inflection point was the most sensitive and informative across all interspecific mixtures for both species. We propose that to reduce bias associated with species size differences when determining reference densities for replacement series experiments, at least two criteria must be met: (1) the experiment sensitivity allows measuring and quantifying the competitive responses for both species in all mixtures, and (2) the balance between density and carrying capacity of the system minimizes intraspecific competition.

Sending microwaves through bauxite ore allows almost continuous measurement of moisture content during offload by conveyor belt from a ship. Data and results from a microwave analyser were brought to a European Study Group with Industry at the University of Limerick, with the over-arching question of whether the results are accurate enough. The analyser equipment uses linear regression against phase shifts and signal attenuation to infer moisture content in real time. Simple initial modelling conducted during the Study Group supports this use of linear regression for phase shift data. However, that work also revealed striking and puzzling differences between model and attenuation data.

We present an improved model that allows for multiple reflections of travelling microwaves within the bauxite and in the air above it. Our new model uses four differential equations to describe how electric fields change with distance in each of four layers. By solving these equations and taking reflections into account, we can accurately predict what the receiving antenna will pick up.

Our new solution provides much-improved matches to data from the microwave analyser, and indicates the deleterious effects of reflections. Modelled signal strength behaviour features a highly undesirable noninvertible dependence on bauxite mixture permittivity.

Practical measures that might be expected to reduce the effects of microwave reflections and improve the accuracy of microwave analyser results are suggested based on our improved model solution. This modelling approach and these results are anticipated to extend to the analysis of moisture content during transport on conveyor belts of other ores, slurries, coal, grains and pharmaceutical powders, especially when the depth of the conveyed material is variable.

The axial offset joint has two rotating axes that do not intersect but have a specific offset in space. It is used widely in parallel manipulators (PMs). The offset-joint workspace can directly affect the PM workspace. This study performed a theoretical derivation and workspace analysis of a class of axial offset joints. First, a theoretical parametric model describing the rotation range of the offset joint is established that considers the interference of the offset joint because of the contact between the upper- and lower-joint brackets during movement. Second, the analytical expressions of the offset-joint workspace are formulated based on the coordinate system transformation. The offset-joint workspace is theoretically calculated in this study using formulations. Then, through a comparative analysis, the superiority of the offset joint compared with the universal joint is verified. The theoretical formulations in this paper can be used to calculate the workspace of a class of axial offset joints. Finally, based on a workspace analysis of three types of PMs using offset, universal, and spherical joints, the offset-joint PM workspace is much larger than those of the other two types.

The Arctic region is rapidly changing as a result of climate alteration, political tensions and ambitions of the Arctic and non-Arctic states. Is the existing governance considered to be adequate for effective international security cooperation in the region? On the one hand, we look optimistic at the evolution of international relations in the areas of science and technology, conservation, search and rescue coordination, tourism, etc. On the other hand, there is a significantly increased militarisation of the Arctic region. The recent rise in military activities in the North has resulted in numerous regional deployments, patrols and other incidents in the maritime Arctic. In general, militarisation together with climate change are impacting scientific-commercial activities. Also, the absence of an adequate legal regime that may respond to climate change and interruption of civil activities by military exercises in a fast and effective way hampers international cooperation. This paper problematises various aspects of interaction between scientific-commercial activities and naval operations in the Arctic region.