2,244 research outputs found
Can scalable design of wings for flapping wing micro air vehicle be inspired by natural flyers?
Lift production is constantly a great challenge for flapping wing micro air vehicles (MAVs). Designing a workable wing, therefore, plays an essential role. Dimensional analysis is an effective and valuable tool in studying the biomechanics of flyers. In this paper, geometric similarity study is firstly presented. Then, the pw−AR ratio is defined and employed in wing performance estimation before the lumped parameter is induced and utilized in wing design. Comprehensive scaling laws on relation of wing performances for natural flyers are next investigated and developed via statistical analysis before being utilized to examine the wing design. Through geometric similarity study and statistical analysis, the results show that the aspect ratio and lumped parameter are independent on mass, and the lumped parameter is inversely proportional to the aspect ratio. The lumped parameters and aspect ratio of flapping wing MAVs correspond to the range of wing performances of natural flyers. Also, the wing performances of existing flapping wing MAVs are examined and follow the scaling laws. Last, the manufactured wings of the flapping wing MAVs are summarized. Our results will, therefore, provide a simple but powerful guideline for biologists and engineers who study the morphology of natural flyers and design flapping wing MAVs
Competing Magnetic Orderings and Tunable Topological States in Two-Dimensional Hexagonal Organometallic Lattices
The exploration of topological states is of significant fundamental and
practical importance in contemporary condensed matter physics, for which the
extension to two-dimensional (2D) organometallic systems is particularly
attractive. Using first-principles calculations, we show that a 2D hexagonal
triphenyl-lead lattice composed of only main group elements is susceptible to a
magnetic instability, characterized by a considerably more stable
antiferromagnetic (AFM) insulating state rather than the topologically
nontrivial quantum spin Hall state proposed recently. Even though this AFM
phase is topologically trivial, it possesses an intricate emergent degree of
freedom, defined by the product of spin and valley indices, leading to Berry
curvature-induced spin and valley currents under electron or hole doping.
Furthermore, such a trivial band insulator can be tuned into a topologically
nontrivial matter by the application of an out-of-plane electric field, which
destroys the AFM order, favoring instead ferrimagnetic spin ordering and a
quantum anomalous Hall state with a non-zero topological invariant. These
findings further enrich our understanding of 2D hexagonal organometallic
lattices for potential applications in spintronics and valleytronics.Comment: 9 pages, 8 figure
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Effects of High-Level Acylsugar-Producing Tomato Lines on the Development of Tomato Psyllids (Hemiptera: Triozidae).
Acylsugars have been shown to provide activity against numerous insect pests of tomatoes. Comparison of acylsugar levels in four tomato plant lines, FA7/AS, FA2/AS, CU071026, and 'Yellow Pear', found that the acylsugar contents in the elevated acylsugar lines were significantly higher than the commercial Yellow Pear (control) tomato plant line. Adult choice tests indicated that the tomato psyllid, Bactericera cockerelli, preferred to settle on the Yellow Pear and FA2/AS lines over the line with the highest content of acylsugars, FA7/AS, and the parental line, CU071026. The no-choice test demonstrated that adults laid fewer eggs on the high acylsugar tomato lines than on the control tomato line, Yellow Pear. For all high acylsugar lines, the relative growth index of the psyllid was significantly lower compared with the commercial line, indicating a reduced potential for population growth. Although some tomato psyllids completed their life cycle on the high acylsugar tomato plant lines, the percent survival of psyllids to the adult stage when developing on the high acylsugar lines was significantly less (range = 43.7-57.1%) than on the commercial tomato line (83.8%). All mortality occurred during the early stages of development (egg stage to third instar), which has implications for acquisition and transmission of Candidatus Liberibacter solanacearum, the causal agent of tomato vein greening disease. Therefore, with reduced attractiveness for tomato psyllids and significantly reduced survival, the high-acylsugar tomato plant lines have the potential to be part of an integrated pest management program for this pest
KALM: Knowledge-Aware Integration of Local, Document, and Global Contexts for Long Document Understanding
With the advent of pre-trained language models (LMs), increasing research
efforts have been focusing on infusing commonsense and domain-specific
knowledge to prepare LMs for downstream tasks. These works attempt to leverage
knowledge graphs, the de facto standard of symbolic knowledge representation,
along with pre-trained LMs. While existing approaches leverage external
knowledge, it remains an open question how to jointly incorporate knowledge
graphs representing varying contexts, from local (e.g., sentence), to
document-level, to global knowledge, to enable knowledge-rich and interpretable
exchange across these contexts. Such rich contextualization can be especially
beneficial for long document understanding tasks since standard pre-trained LMs
are typically bounded by the input sequence length. In light of these
challenges, we propose KALM, a Knowledge-Aware Language Model that jointly
leverages knowledge in local, document-level, and global contexts for long
document understanding. KALM first encodes long documents and knowledge graphs
into the three knowledge-aware context representations. It then processes each
context with context-specific layers, followed by a context fusion layer that
facilitates interpretable knowledge exchange to derive an overarching document
representation. Extensive experiments demonstrate that KALM achieves
state-of-the-art performance on three long document understanding tasks across
6 datasets/settings. Further analyses reveal that the three knowledge-aware
contexts are complementary and they all contribute to model performance, while
the importance and information exchange patterns of different contexts vary
with respect to different tasks and datasets
Generalized Minimum Error Entropy for Adaptive Filtering
Error entropy is a important nonlinear similarity measure, and it has
received increasing attention in many practical applications. The default
kernel function of error entropy criterion is Gaussian kernel function,
however, which is not always the best choice. In our study, a novel concept,
called generalized error entropy, utilizing the generalized Gaussian density
(GGD) function as the kernel function is proposed. We further derivate the
generalized minimum error entropy (GMEE) criterion, and a novel adaptive
filtering called GMEE algorithm is derived by utilizing GMEE criterion. The
stability, steady-state performance, and computational complexity of the
proposed algorithm are investigated. Some simulation indicate that the GMEE
algorithm performs well in Gaussian, sub-Gaussian, and super-Gaussian noises
environment, respectively. Finally, the GMEE algorithm is applied to acoustic
echo cancelation and performs well.Comment: 9 pages, 8 figure
Dynamic aspiration based on Win-Stay-Lose-Learn rule in Spatial Prisoner's Dilemma Gam
Prisoner's dilemma game is the most commonly used model of spatial
evolutionary game which is considered as a paradigm to portray competition
among selfish individuals. In recent years, Win-Stay-Lose-Learn, a strategy
updating rule base on aspiration, has been proved to be an effective model to
promote cooperation in spatial prisoner's dilemma game, which leads aspiration
to receive lots of attention. But in many research the assumption that
individual's aspiration is fixed is inconsistent with recent results from
psychology. In this paper, according to Expected Value Theory and Achievement
Motivation Theory, we propose a dynamic aspiration model based on
Win-Stay-Lose-Learn rule in which individual's aspiration is inspired by its
payoff. It is found that dynamic aspiration has a significant impact on the
evolution process, and different initial aspirations lead to different results,
which are called Stable Coexistence under Low Aspiration, Dependent Coexistence
under Moderate aspiration and Defection Explosion under High Aspiration
respectively. Furthermore, a deep analysis is performed on the local structures
which cause cooperator's existence or defector's expansion, and the evolution
process for different parameters including strategy and aspiration. As a
result, the intrinsic structures leading to defectors' expansion and
cooperators' survival are achieved for different evolution process, which
provides a penetrating understanding of the evolution. Compared to fixed
aspiration model, dynamic aspiration introduces a more satisfactory explanation
on population evolution laws and can promote deeper comprehension for the
principle of prisoner's dilemma.Comment: 17 pages, 13 figure
Enhancing Subtask Performance of Multi-modal Large Language Model
Multi-modal Large Language Model (MLLM) refers to a model expanded from a
Large Language Model (LLM) that possesses the capability to handle and infer
multi-modal data. Current MLLMs typically begin by using LLMs to decompose
tasks into multiple subtasks, then employing individual pre-trained models to
complete specific subtasks, and ultimately utilizing LLMs to integrate the
results of each subtasks to obtain the results of the task. In real-world
scenarios, when dealing with large projects, it is common practice to break
down the project into smaller sub-projects, with different teams providing
corresponding solutions or results. The project owner then decides which
solution or result to use, ensuring the best possible outcome for each subtask
and, consequently, for the entire project. Inspired by this, this study
considers selecting multiple pre-trained models to complete the same subtask.
By combining the results from multiple pre-trained models, the optimal subtask
result is obtained, enhancing the performance of the MLLM. Specifically, this
study first selects multiple pre-trained models focused on the same subtask
based on distinct evaluation approaches, and then invokes these models in
parallel to process input data and generate corresponding subtask results.
Finally, the results from multiple pre-trained models for the same subtask are
compared using the LLM, and the best result is chosen as the outcome for that
subtask. Extensive experiments are conducted in this study using GPT-4
annotated datasets and human-annotated datasets. The results of various
evaluation metrics adequately demonstrate the effectiveness of the proposed
approach in this paper
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