38 research outputs found
Optimization of Location-Routing for the Waste Household Appliances Recycling Logistics under the Uncertain Condition
Waste household appliances and electronic products usually contain harmful substances which need scientific and reasonable collection, classification, processing, recovery and disposal to achieve sustainable and effective recycling and utilization. In recent years, due to the poor management of waste household appliances recycling logistics system, safety accidents occur frequently, which seriously harm the health and life safety of the society. This paper studies the risk management of recycling waste household appliances under uncertain conditions and establishes a risk measurement model under fuzzy population density. Considering the multi-stage and classification diversity of waste household appliances recycling logistics, the multi-objective location routing model and location - routing model are established respectively. Based on the model complexity analysis, the solution method of multi-objective model is designed. Finally, the validity of the model and algorithm is verified by examples and tests
Adapt Anything: Tailor Any Image Classifiers across Domains And Categories Using Text-to-Image Diffusion Models
We do not pursue a novel method in this paper, but aim to study if a modern
text-to-image diffusion model can tailor any task-adaptive image classifier
across domains and categories. Existing domain adaptive image classification
works exploit both source and target data for domain alignment so as to
transfer the knowledge learned from the labeled source data to the unlabeled
target data. However, as the development of the text-to-image diffusion model,
we wonder if the high-fidelity synthetic data from the text-to-image generator
can serve as a surrogate of the source data in real world. In this way, we do
not need to collect and annotate the source data for each domain adaptation
task in a one-for-one manner. Instead, we utilize only one off-the-shelf
text-to-image model to synthesize images with category labels derived from the
corresponding text prompts, and then leverage the surrogate data as a bridge to
transfer the knowledge embedded in the task-agnostic text-to-image generator to
the task-oriented image classifier via domain adaptation. Such a one-for-all
adaptation paradigm allows us to adapt anything in the world using only one
text-to-image generator as well as the corresponding unlabeled target data.
Extensive experiments validate the feasibility of the proposed idea, which even
surpasses the state-of-the-art domain adaptation works using the source data
collected and annotated in real world.Comment: 11 pages, 6 figure
Observation of first-order quantum phase transitions and ferromagnetism in twisted double bilayer graphene
Twisted graphene multilayers are highly tunable flatband systems for
developing new phases of matter. Thus far, while orbital ferromagnetism has
been observed in valley polarized phases, the long-range orders of other
correlated phases as well as the quantum phase transitions between different
orders mostly remain unknown. Here, we report an observation of Coulomb
interaction driven first-order quantum phase transitions and ferromagnetism in
twisted double bilayer graphene (TDBG). At zero magnetic field, the transitions
are revealed in a series of step-like abrupt resistance jumps with prominent
hysteresis loop when either the displacement field (D) or the carrier density
(n) is tuned across symmetry-breaking boundary near half filling, indicating a
formation of ordered domains. It is worth noting that the good turnability and
switching of these states gives a rise to a memory performance with a large
on/off ratio. Moreover, when both spin and valley play the roles at finite
magnetic field, we observe abundant first-order quantum phase transitions among
normal metallic states from charge neutral point, orbital ferromagnetic states
from quarter filling, and spin-polarized states from half filling. We interpret
these first-order phase transitions in the picture of phase separations and
spin domain percolations driven by multi-field tunable Coulomb interactions, in
agreement with Lifshitz transition from Hartree-Fock calculations. The observed
multi-filed tunable domain structure and its hysteresis resembles the
characteristics of multiferroics, revealing intriguing magnetoelectric
properties. Our result enriches the correlated phase diagram in TDBG for
discovering novel exotic phases and quantum phase transitions, and it would
benefit other twisted moir\'e systems as well
Layer-by-Layer Epitaxy of Multilayer MoS2 Wafers
Two-dimensional (2D) semiconductor of MoS2 has great potential for advanced
electronics technologies beyond silicon1-9. So far, high-quality monolayer MoS2
wafers10-12 are already available and various demonstrations from individual
transistors to integrated circuits have also been shown13-15. In addition to
the monolayer, multilayers have narrower band gaps but improved carrier
mobilities and current capacities over the monolayer5,16-18. However, achieving
high-quality multilayer MoS2 wafers remains a challenge. Here we report the
growth of high quality multilayer MoS2 4-inch wafers via the layer-by-layer
epitaxy process. The epitaxy leads to well-defined stacking orders between
adjacent epitaxial layers and offers a delicate control of layer numbers up to
6. Systematic evaluations on the atomic structures and electronic properties
were carried out for achieved wafers with different layer numbers. Significant
improvements on device performances were found in thicker-layer field effect
transistors (FETs), as expected. For example, the average field-effect mobility
({\mu}FE) at room temperature (RT) can increase from ~80 cm2V-1s-1 for
monolayer to ~110/145 cm2V-1s-1 for bilayer/trilayer devices. The highest RT
{\mu}FE=234.7 cm2V-1s-1 and a record-high on-current densities of 1.704
mA{\mu}m-1 at Vds=2 V were also achieved in trilayer MoS2 FETs with a high
on/off ratio exceeding 107. Our work hence moves a step closer to practical
applications of 2D MoS2 in electronics.Comment: 13 pages,4 Figure
Rate-Induced Transitions in Networked Complex Adaptive Systems: Exploring Dynamics and Management Implications Across Ecological, Social, and Socioecological Systems
Complex adaptive systems (CASs), from ecosystems to economies, are open
systems and inherently dependent on external conditions. While a system can
transition from one state to another based on the magnitude of change in
external conditions, the rate of change -- irrespective of magnitude -- may
also lead to system state changes due to a phenomenon known as a rate-induced
transition (RIT). This study presents a novel framework that captures RITs in
CASs through a local model and a network extension where each node contributes
to the structural adaptability of others. Our findings reveal how RITs occur at
a critical environmental change rate, with lower-degree nodes tipping first due
to fewer connections and reduced adaptive capacity. High-degree nodes tip later
as their adaptability sources (lower-degree nodes) collapse. This pattern
persists across various network structures. Our study calls for an extended
perspective when managing CASs, emphasizing the need to focus not only on
thresholds of external conditions but also the rate at which those conditions
change, particularly in the context of the collapse of surrounding systems that
contribute to the focal system's resilience. Our analytical method opens a path
to designing management policies that mitigate RIT impacts and enhance
resilience in ecological, social, and socioecological systems. These policies
could include controlling environmental change rates, fostering system
adaptability, implementing adaptive management strategies, and building
capacity and knowledge exchange. Our study contributes to the understanding of
RIT dynamics and informs effective management strategies for complex adaptive
systems in the face of rapid environmental change.Comment: 25 pages, 4 figures, 1 box, supplementary informatio
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Life history and temporal variability of escape events interactively determine the fitness consequences of aquaculture escapees on wild populations.
Domesticated individuals are likely to be maladaptive in the wild due to adaptation to captivity. Escaped aquaculture fish can cause unintended fitness and demographic consequences for their wild conspecifics through interbreeding and competition. Escape events from different sources exhibit great heterogeneity in their frequencies and magnitudes, ranging from rare but large spillover during a storm, to continuous low-level leakage caused by operational errors. The timescale of escape events determines the distribution of gene flow from aquaculture to the wild. The evolutionary consequences of this variation in timescale will depend on the degree of generation overlap and the focal species' life history attributes, especially those under selection in aquaculture (e.g., growth rate, which can influence additional demographically important traits such as age at maturity). To evaluate the effects of variable escape both within and across generations, we construct an age-structured model of coupled genetic and demographic dynamics and parameterize it for species with contrasting life history characteristics (Salmo salar and Gadus morhua). Our results are consistent with earlier discrete-generation models that constant, low-level spillover can have a greater impact than rare, large pulses of leakage, even after accounting for the averaging effects of overlapping generations. The age-structured model also allows detailed evaluation of the role of different life history traits, which reveals that species with longer generation times might experience greater fitness consequences of aquaculture spillover but are less sensitive to variability in spillover. Additionally, environment-induced earlier maturity of escapees can increase the fitness effects on wild fish, especially those with shorter generation times. Our results suggest that effective management to minimize the unintended fitness consequences of aquaculture releases might require extensive monitoring efforts on constant, low-level spillover and assessment of the focal species' life history characteristics
Recommended from our members
Life history and temporal variability of escape events interactively determine the fitness consequences of aquaculture escapees on wild populations.
Domesticated individuals are likely to be maladaptive in the wild due to adaptation to captivity. Escaped aquaculture fish can cause unintended fitness and demographic consequences for their wild conspecifics through interbreeding and competition. Escape events from different sources exhibit great heterogeneity in their frequencies and magnitudes, ranging from rare but large spillover during a storm, to continuous low-level leakage caused by operational errors. The timescale of escape events determines the distribution of gene flow from aquaculture to the wild. The evolutionary consequences of this variation in timescale will depend on the degree of generation overlap and the focal species' life history attributes, especially those under selection in aquaculture (e.g., growth rate, which can influence additional demographically important traits such as age at maturity). To evaluate the effects of variable escape both within and across generations, we construct an age-structured model of coupled genetic and demographic dynamics and parameterize it for species with contrasting life history characteristics (Salmo salar and Gadus morhua). Our results are consistent with earlier discrete-generation models that constant, low-level spillover can have a greater impact than rare, large pulses of leakage, even after accounting for the averaging effects of overlapping generations. The age-structured model also allows detailed evaluation of the role of different life history traits, which reveals that species with longer generation times might experience greater fitness consequences of aquaculture spillover but are less sensitive to variability in spillover. Additionally, environment-induced earlier maturity of escapees can increase the fitness effects on wild fish, especially those with shorter generation times. Our results suggest that effective management to minimize the unintended fitness consequences of aquaculture releases might require extensive monitoring efforts on constant, low-level spillover and assessment of the focal species' life history characteristics
Dynamic Domain Generalization
Domain generalization (DG) is a fundamental yet very challenging research
topic in machine learning. The existing arts mainly focus on learning
domain-invariant features with limited source domains in a static model.
Unfortunately, there is a lack of training-free mechanism to adjust the model
when generalized to the agnostic target domains. To tackle this problem, we
develop a brand-new DG variant, namely Dynamic Domain Generalization (DDG), in
which the model learns to twist the network parameters to adapt the data from
different domains. Specifically, we leverage a meta-adjuster to twist the
network parameters based on the static model with respect to different data
from different domains. In this way, the static model is optimized to learn
domain-shared features, while the meta-adjuster is designed to learn
domain-specific features. To enable this process, DomainMix is exploited to
simulate data from diverse domains during teaching the meta-adjuster to adapt
to the upcoming agnostic target domains. This learning mechanism urges the
model to generalize to different agnostic target domains via adjusting the
model without training. Extensive experiments demonstrate the effectiveness of
our proposed method. Code is available at: https://github.com/MetaVisionLab/DDGComment: Accepted by IJCAI 202