6,280 research outputs found
Solving bilevel programs based on lower-level Mond-Weir duality
This paper focuses on developing effective algorithms for solving bilevel
program. The most popular approach is to replace the lower-level problem by its
Karush-Kuhn-Tucker conditions to generate a mathematical program with
complementarity constraints (MPCC). However, MPCC does not satisfy the
Mangasarian-Fromovitz constraint qualification (MFCQ) at any feasible point. In
this paper, inspired by a recent work using the lower-level Wolfe duality
(WDP), we apply the lower-level Mond-Weir duality to present a new
reformulation, called MDP, for bilevel program. It is shown that, under mild
assumptions, they are equivalent in globally or locally optimal sense. An
example is given to show that, different from MPCC, MDP may satisfy the MFCQ at
its feasible points. Relations among MDP, WDP, and MPCC are investigated.
Furthermore, in order to compare the new MDP approach with the MPCC and WDP
approaches, we design a procedure to generate 150 tested problems randomly and
comprehensive numerical experiments showed that MDP has evident advantages over
MPCC and WDP in terms of feasibility to the original bilevel programs, success
efficiency, and average CPU time.Comment: arXiv admin note: text overlap with arXiv:2302.0683
A novel decomposed-ensemble time series forecasting framework: capturing underlying volatility information
Time series forecasting represents a significant and challenging task across
various fields. Recently, methods based on mode decomposition have dominated
the forecasting of complex time series because of the advantages of capturing
local characteristics and extracting intrinsic modes from data. Unfortunately,
most models fail to capture the implied volatilities that contain significant
information. To enhance the prediction of contemporary diverse and complex time
series, we propose a novel time series forecasting paradigm that integrates
decomposition with the capability to capture the underlying fluctuation
information of the series. In our methodology, we implement the Variational
Mode Decomposition algorithm to decompose the time series into K distinct
sub-modes. Following this decomposition, we apply the Generalized
Autoregressive Conditional Heteroskedasticity (GARCH) model to extract the
volatility information in these sub-modes. Subsequently, both the numerical
data and the volatility information for each sub-mode are harnessed to train a
neural network. This network is adept at predicting the information of the
sub-modes, and we aggregate the predictions of all sub-modes to generate the
final output. By integrating econometric and artificial intelligence methods,
and taking into account both the numerical and volatility information of the
time series, our proposed framework demonstrates superior performance in time
series forecasting, as evidenced by the significant decrease in MSE, RMSE, and
MAPE in our comparative experimental results
Effect of a poloxamer 407-based thermosensitive gel on minimization of thermal injury to diaphragm during microwave ablation of the liver.
AIM: To assess the insulating effect of a poloxamer 407 (P407)-based gel during microwave ablation of liver adjacent to the diaphragm.
METHODS: We prepared serial dilutions of P407, and 22.5% (w/w) concentration was identified as suitable for ablation procedures. Subsequently, microwave ablations were performed on the livers of 24 rabbits (gel, saline, control groups, n = 8 in each). The P407 solution and 0.9% normal saline were injected into the potential space between the diaphragm and liver in experimental groups. No barriers were applied to the controls. After microwave ablations, the frequency, size and degree of thermal injury were compared histologically among the three groups. Subsequently, another 8 rabbits were injected with the P407 solution and microwave ablation was performed. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN) and creatinine (Cr) in serum were tested at 1 d before microwave ablation and 3 and 7 d after operation.
RESULTS: In vivo ablation thermal injury to the adjacent diaphragm was evaluated in the control, saline and 22.5% P407 gel groups (P = 0.001-0.040). However, there was no significant difference in the volume of ablation zone among the three groups (P \u3e 0.05). Moreover, there were no statistical differences among the preoperative and postoperative gel groups according to the levels of ALT, AST, BUN and Cr in serum (all P \u3e 0.05).
CONCLUSION: Twenty-two point five percent P407 gel could be a more effective choice during microwave ablation of hepatic tumors adjacent to the diaphragm. Further studies for clinical translation are warranted
InterDiff: Generating 3D Human-Object Interactions with Physics-Informed Diffusion
This paper addresses a novel task of anticipating 3D human-object
interactions (HOIs). Most existing research on HOI synthesis lacks
comprehensive whole-body interactions with dynamic objects, e.g., often limited
to manipulating small or static objects. Our task is significantly more
challenging, as it requires modeling dynamic objects with various shapes,
capturing whole-body motion, and ensuring physically valid interactions. To
this end, we propose InterDiff, a framework comprising two key steps: (i)
interaction diffusion, where we leverage a diffusion model to encode the
distribution of future human-object interactions; (ii) interaction correction,
where we introduce a physics-informed predictor to correct denoised HOIs in a
diffusion step. Our key insight is to inject prior knowledge that the
interactions under reference with respect to contact points follow a simple
pattern and are easily predictable. Experiments on multiple human-object
interaction datasets demonstrate the effectiveness of our method for this task,
capable of producing realistic, vivid, and remarkably long-term 3D HOI
predictions.Comment: ICCV 2023; Project Page: https://sirui-xu.github.io/InterDiff
Axial Force Analysis and Roll Contour Configuration of Four-High CVC Mill
In order to analyze the influence of technical parameters on work roll axial force of four-high continuous variable crown (CVC) mill, the deformation analyzing model with top roll system and strip was established based on influence function method. Then a CVC work roll curve designing scheme was proposed and it was carried out on some cold rolling mill considering the requirement of comprehensive work roll axial force minimization. The status of comprehensive work roll axial force is improved considering the rolling schedule that is beneficial to the roller bearing. Corresponding to the newly designed work roll contour, the backup roll end chamfer was designed considering comprehensive performance of interroll stress concentration, comprehensive work roll axial force, and strip shape control ability. The distribution of roll wear with newly designed backup roll contour is more even according to the field application data. The newly established roll configuration scheme is beneficial to four-high CVC mill
- …