766 research outputs found
Improved Algorithms for Online Rent Minimization Problem Under Unit-Size Jobs
Get PDFWe consider the Online Rent Minimization problem, where online jobs with release times, deadlines, and processing times must be scheduled on machines that can be rented for a fixed length period of T. The objective is to minimize the number of machine rents. This problem generalizes the Online Machine Minimization problem where machines can be rented for an infinite period, and both problems have an asymptotically optimal competitive ratio of O(log(p_max/p_min)) for general processing times, where p_max and p_min are the maximum and minimum processing times respectively. However, for small values of p_max/p_min, a better competitive ratio can be achieved by assuming unit-size jobs. Under this assumption, Devanur et al. (2014) gave an optimal e-competitive algorithm for Online Machine Minimization, and Chen and Zhang (2022) gave a (3e+7) ≈ 15.16-competitive algorithm for Online Rent Minimization. In this paper, we significantly improve the competitive ratio of the Online Rent Minimization problem under unit size to 6, by using a clean oracle-based online algorithm framework
A numerical investigation of the airfoil-gust interaction noise in transonic flows: Acoustic processes
No full textThe sound produced by airfoil-gust interaction is a significant source of broadband noise in turbofan engines or contra-rotating open rotors (CRORs). There are competing mechanisms in this regime because of the presence of shocks that were seldom considered in the previous subsonic studies. A numerical investigation of airfoil-gust interaction noise at transonic speeds is undertaken in this work. By introducing vortical gust/synthetic turbulence to specified regions in the computational domain to interact with different elements in the flow field, it is shown that the dominant sound source is caused by leading edge-gust interaction. It is demonstrated that both streamwise and transverse disturbances interact with the near-field non-uniform mean flow and shocks can produce sound using a local gust injection method. The propagation of sound is significantly influenced by the presence of the shocks, and the far field radiation pattern is changed. We also study the effect of gust strength on the near and far field properties. The linearity is maintained for gust strength smaller than 1.0% of the mean flow velocity. Otherwise, the shocks may experience oscillations that will alter the near-field aerodynamics and far-field radiation.</p
Artificial damping methods for stable computations with linearized Euler equations
No full textIn this work, new methods are developed to facilitate stable and accurate numerical solutions of linearized Euler equations, which are often used in solving problems in computational aeroacoustics. Solutions of LEE can suffer from numerical Kelvin-Helmholtz instabilities in the presence of a sheared mean flow. Various methods have been exploited to address this problem; each has its advantages and disadvantages. In this work, two new methods that use artificial damping terms (ADT) are introduced. The first method is constructed to damp the vortical components generated during the computation while the second one is proposed by revisiting the effect of viscosity in the Navier-Stokes equations.An adaptive method is also used to improve the proposed new methods. These methods are tested on two benchmark cases: a) acoustic wave refraction through a strongly sheared jet, and b) mode radiation from a semi-infinite duct with jet. It is found that numerical instabilities can be successfully suppressed with little side effect on the acoustic wave computations.<br/
Geometry effect on the airfoil-gust interaction noise in transonic flows
No full textNumerical simulations are conducted to investigate the impacts of airfoil thickness, the angle of attack and camber on the airfoil-gust interaction noise in transonic flows where locally supersonic regimes and terminating shocks are present. The conclusions about the geometry effects based on the extensively studied subsonic cases are revisited. With the increase of airfoil thickness, the sound generation is reduced in the downstream direction as in subsonic flows. More sound is produced in the upstream direction for thicker airfoils due to the non-uniform mean flow and shocks in the near field. The compensative effect makes the overall sound reduction by the airfoil thickness less than the subsonic cases despite the significant difference in the radiation patterns. The acoustic responses to the single frequency gusts are sensitive to the airfoil angle of attack in transonic flows. However, the overall differences are reduced when multiple wavenumber components are superposed in isotropic turbulence, and the sound pressure levels are therefore close as in subsonic flows. Similarly, the significant variations in single frequency acoustic responses by airfoil camber are averaged by the superposition of various wavenumber components. However, apparent variations are still found in the upstream direction, especially for the turbulences with small integral length scales.</p
The intervention effect of Aitongxiao prescription on primary liver cancer rats was evaluated based on high-throughput miRNA sequencing and bioinformatics analysis
No full textLiver cancer is a common malignant tumor known for its difficult treatment and poor prognosis. As a traditional Chinese medicine prescription, Aitongxiao prescription (ATXP) has been used in clinical treatment of primary liver cancer (PLC) for more than ten years, and its therapeutic effect is obvious and has been verified over time. However, the mechanism of ATXP in treating PLC has not been fully elucidated. This study aimed to detect the liver-protective effect of ATXP on a PLC rat model and explore its potential mechanism from the perspective of plasma extracellular vesicle miRNAs. Fifty SPF male SD rats were randomly selected, with six rats as the control group, and the remaining rats were injected with DEN to establish a primary liver cancer model. The model rats were randomly divided into the model group and the ATXP group. After 4 weeks of intervention, the liver-protective effect of ATXP was evaluated using plasma biochemical indicators and histopathological methods. Plasma extracellular vesicles were isolated and extracted, and identified by transmission electron microscopy, nanoparticle tracking analysis, and western blot. Significant differentially expressed miRNAs in extracellular vesicles were screened by Illumina sequencing to explore the therapeutic targets of ATXP and conduct functional analysis. The results showed that ATXP significantly reduced plasma liver function in PLC rats and alleviated liver pathological damage. In addition, plasma extracellular vesicles were isolated and identified. According to the results of GO and KEGG analysis, they were related to multiple biological processes and covered multiple signaling pathways (PI3K-Akt and MAPK signaling pathways, etc.). The interaction between miR-199a-3p and MAP3K4 was determined by bioinformatics methods and dual-luciferase reporter gene detection, confirming that MAP3K4 is the target gene of miR-199a-3p. In conclusion, ATXP protects the liver from DEN-induced PLC, which may be related to the regulation of plasma extracellular vesicle miR-199a-3p. This study further reveals the mechanism of ATXP in treating liver cancer and provides a theoretical basis for subsequent research
sj-docx-1-tag-10.1177_17562848221127474 – Supplemental material for Associations between inflammatory bowel disease, social isolation, and mortality: evidence from a longitudinal cohort study
No full textSupplemental material, sj-docx-1-tag-10.1177_17562848221127474 for Associations between inflammatory bowel disease, social isolation, and mortality: evidence from a longitudinal cohort study by Jie Chen, Jiawei Geng, Jiayi Wang, Zhenhua Wu, Tian Fu, Yuhao Sun, Xuejie Chen, Xiaoyan Wang and Therese Hesketh in Therapeutic Advances in Gastroenterology</p
sj-docx-1-tag-10.1177_17562848231207305 – Supplemental material for Associations of sugar-sweetened beverages, artificially sweetened beverages, and natural juices with cardiovascular disease and all-cause mortality in individuals with inflammatory bowel disease in a prospective cohort study
No full textSupplemental material, sj-docx-1-tag-10.1177_17562848231207305 for Associations of sugar-sweetened beverages, artificially sweetened beverages, and natural juices with cardiovascular disease and all-cause mortality in individuals with inflammatory bowel disease in a prospective cohort study by Lintao Dan, Tian Fu, Yuhao Sun, Xixian Ruan, Shiyuan Lu, Jie Chen and Xiaoyan Wang in Therapeutic Advances in Gastroenterology</p
Secure Source Identification Scheme for Revocable Instruction Sharing in Vehicle Platoon
No full textThe secure transmission of instructions among vehicles in a platoon is one of the most essential needs for a vehicle platoon. Despite the existence of cryptographic methods to securely share instructions, instruction sharing is still subject to forgery, tampering, and denial-of-service attacks. Therefore, it is urgent to find a solution to perform data source identification to filter out irrelevant information (not instructions) while ensuring the authenticity of encrypted instructions is urgent to address. In addition, immediate revocation of credentials is also a crucial requirement for a vehicle platoon when an authorized vehicle member misbehaves. In this paper, we propose the first Secure Source Identification Scheme for Revocable Instruction Sharing (SI-RIS) to securely simultaneously achieve bilateral fine-grained access control, data source identification, immediate vehicle user revocation, and efficient encryption in vehicle platoons. Specifically, our SI-RIS solution supports fine-grained access control for both the sender and receiver over the encrypted instructions. As a result, only authorized correspondents are able to access the commands. Furthermore, upon identification of malicious members in the platoon, our SI-RIS provides an efficient direct vehicle user revocation mechanism capable of immediate revocation credentials without affecting other vehicles. We prove the security of our SI-RIS via rigorous mathematical security proof. Moreover, performance evaluation and comparisons illustrate the feasibility and practicability of SI-RIS for vehicle platoon
The specific contribution of object's origin on artifacts categorization
No full textGelman and Bloom found that adults and children's object naming was sensitive to how an object was created (man-made or not), but they did not reveal on which specific level of conceptual system this effect was. Using a free-naming task and a force-choice task, two experiments were conducted to test a hypothesis that this effect was specifically on domain level ("artifact/non-artifact" distinction). In Experiment 1, participants were asked to name shortly-depicted objects, rate their confidence, and report their reasons for each naming response. Results showed that most of the naming responses in "man-made" condition were in artifact domain, and most in "natural" condition were in non-artifact domain, although in both conditions names were very divergent on basic level. In Experiment 2, another group of participants were asked to choose one from two names (one in artifact domain and the other in non-artifact domain) to match the same shortly-depicted objects presented in the first experiment. Results of Experiment 1 on domain level were replicated in Experiment 2. These convergent findings supported the hypothesis that the effect of object's origin is specifically on domain level of conceptual system of objects. Reasons explicitly reported for naming responses in Experiment 1 suggested that participants might automatically infer objects' functions in "man-made" condition but not in "natural" condition. Here the function-based hypothesis of artifacts classification is discussed.Gelman and Bloom found that adults and children's object naming was sensitive to how an object was created (man-made or not), but they did not reveal on which specific level of conceptual system this effect was. Using a free-naming task and a force-choice task, two experiments were conducted to test a hypothesis that this effect was specifically on domain level ("artifact/non-artifact" distinction). In Experiment 1, participants were asked to name shortly-depicted objects, rate their confidence, and report their reasons for each naming response. Results showed that most of the naming responses in "man-made" condition were in artifact domain, and most in "natural" condition were in non-artifact domain, although in both conditions names were very divergent on basic level. In Experiment 2, another group of participants were asked to choose one from two names (one in artifact domain and the other in non-artifact domain) to match the same shortly-depicted objects presented in the first experiment. Results of Experiment 1 on domain level were replicated in Experiment 2. These convergent findings supported the hypothesis that the effect of object's origin is specifically on domain level of conceptual system of objects. Reasons explicitly reported for naming responses in Experiment 1 suggested that participants might automatically infer objects' functions in "man-made" condition but not in "natural" condition. Here the function-based hypothesis of artifacts classification is discussed
Insight-V: Exploring Long-Chain Visual Reasoning with Multimodal Large Language Models
No full textLarge Language Models (LLMs) demonstrate enhanced capabilities and reliability by reasoning more, evolving from Chain-of-Thought prompting to product-level solutions like OpenAI o1. Despite various efforts to improve LLM reasoning, high-quality long-chain reasoning data and optimized training pipelines still remain inadequately explored in vision-language tasks. In this paper, we present Insight-V, an early effort to 1) scalably produce long and robust reasoning data for complex multi-modal tasks, and 2) an effective training pipeline to enhance the reasoning capabilities of multi-modal large language models (MLLMs). Specifically, to create long and structured reasoning data without human labor, we design a two-step pipeline with a progressive strategy to generate sufficiently long and diverse reasoning paths and a multi-granularity assessment method to ensure data quality. We observe that directly supervising MLLMs with such long and complex reasoning data will not yield ideal reasoning ability. To tackle this problem, we design a multi-agent system consisting of a reasoning agent dedicated to performing long-chain reasoning and a summary agent trained to judge and summarize reasoning results. We further incorporate an iterative DPO algorithm to enhance the reasoning agent's generation stability and quality. Based on the popular LLaVA-NeXT model and our stronger base MLLM, we demonstrate significant performance gains across challenging multi-modal benchmarks requiring visual reasoning. Benefiting from our multi-agent system, Insight-V can also easily maintain or improve performance on perception-focused multi-modal tasks
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