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Diffusion-based super-resolution (SR) models have recently garnered significant attention due to their potent restoration capabilities. But conventional diffusion models perform noise sampling from a single distribution, constraining their ability to handle real-world scenes and complex textures across semantic regions. With the success of segment anything model (SAM), generating sufficiently fine-grained region masks can enhance the detail recovery of diffusion-based SR model. However, directly integrating SAM into SR models will result in much higher computational cost. In this paper, we propose the SAM-DiffSR model, which can utilize the fine-grained structure information from SAM in the process of sampling noise to improve the image quality without additional computational cost during inference. In the process of training, we encode structural position information into the segmentation mask from SAM. Then the encoded mask is integrated into the forward diffusion process by modulating it to the sampled noise. This adjustment allows us to independently adapt the noise mean within each corresponding segmentation area. The diffusion model is trained to estimate this modulated noise. Crucially, our proposed framework does NOT change the reverse diffusion process and does NOT require SAM at inference. Experimental results demonstrate the effectiveness of our proposed method, showcasing superior performance in suppressing artifacts, and surpassing existing diffusion-based methods by 0.74 dB at the maximum in terms of PSNR on DIV2K dataset. The code and dataset are available at https://github.com/lose4578/SAM-DiffSR.

Training general-purpose vision models on purely sequential visual data, eschewing linguistic inputs, has heralded a new frontier in visual understanding. These models are intended to not only comprehend but also seamlessly transit to out-of-domain tasks. However, current endeavors are hamstrung by an over-reliance on colossal models, exemplified by models with upwards of 3B parameters, and the necessity for an extensive corpus of visual data, often comprising a staggering 400B tokens. In this paper, we delve into the development of an efficient, autoregression-based vision model, innovatively architected to operate on a limited dataset. We meticulously demonstrate how this model achieves proficiency in a spectrum of visual tasks spanning both high-level and low-level semantic understanding during the testing phase. Our empirical evaluations underscore the model's agility in adapting to various tasks, heralding a significant reduction in the parameter footprint, and a marked decrease in training data requirements, thereby paving the way for more sustainable and accessible advancements in the field of generalist vision models. The code is available at https://github.com/ggjy/DeLVM., Comment: 15 pages

Compact neural networks are specially designed for applications on edge devices with faster inference speed yet modest performance. However, training strategies of compact models are borrowed from that of conventional models at present, which ignores their difference in model capacity and thus may impede the performance of compact models. In this paper, by systematically investigating the impact of different training ingredients, we introduce a strong training strategy for compact models. We find that the appropriate designs of re-parameterization and knowledge distillation are crucial for training high-performance compact models, while some commonly used data augmentations for training conventional models, such as Mixup and CutMix, lead to worse performance. Our experiments on ImageNet-1K dataset demonstrate that our specialized training strategy for compact models is applicable to various architectures, including GhostNetV2, MobileNetV2 and ShuffleNetV2. Specifically, equipped with our strategy, GhostNetV3 1.3$\times$ achieves a top-1 accuracy of 79.1% with only 269M FLOPs and a latency of 14.46ms on mobile devices, surpassing its ordinarily trained counterpart by a large margin. Moreover, our observation can also be extended to object detection scenarios. PyTorch code and checkpoints can be found at https://github.com/huawei-noah/Efficient-AI-Backbones/tree/master/ghostnetv3_pytorch.

The tremendous success of large models trained on extensive datasets demonstrates that scale is a key ingredient in achieving superior results. Therefore, the reflection on the rationality of designing knowledge distillation (KD) approaches for limited-capacity architectures solely based on small-scale datasets is now deemed imperative. In this paper, we identify the \emph{small data pitfall} that presents in previous KD methods, which results in the underestimation of the power of vanilla KD framework on large-scale datasets such as ImageNet-1K. Specifically, we show that employing stronger data augmentation techniques and using larger datasets can directly decrease the gap between vanilla KD and other meticulously designed KD variants. This highlights the necessity of designing and evaluating KD approaches in the context of practical scenarios, casting off the limitations of small-scale datasets. Our investigation of the vanilla KD and its variants in more complex schemes, including stronger training strategies and different model capacities, demonstrates that vanilla KD is elegantly simple but astonishingly effective in large-scale scenarios. Without bells and whistles, we obtain state-of-the-art ResNet-50, ViT-S, and ConvNeXtV2-T models for ImageNet, which achieve 83.1\%, 84.3\%, and 85.0\% top-1 accuracy, respectively. PyTorch code and checkpoints can be found at https://github.com/Hao840/vanillaKD.

Knowledge distillation~(KD) has proven to be a highly effective approach for enhancing model performance through a teacher-student training scheme. However, most existing distillation methods are designed under the assumption that the teacher and student models belong to the same model family, particularly the hint-based approaches. By using centered kernel alignment (CKA) to compare the learned features between heterogeneous teacher and student models, we observe significant feature divergence. This divergence illustrates the ineffectiveness of previous hint-based methods in cross-architecture distillation. To tackle the challenge in distilling heterogeneous models, we propose a simple yet effective one-for-all KD framework called OFA-KD, which significantly improves the distillation performance between heterogeneous architectures. Specifically, we project intermediate features into an aligned latent space such as the logits space, where architecture-specific information is discarded. Additionally, we introduce an adaptive target enhancement scheme to prevent the student from being disturbed by irrelevant information. Extensive experiments with various architectures, including CNN, Transformer, and MLP, demonstrate the superiority of our OFA-KD framework in enabling distillation between heterogeneous architectures. Specifically, when equipped with our OFA-KD, the student models achieve notable performance improvements, with a maximum gain of 8.0% on the CIFAR-100 dataset and 0.7% on the ImageNet-1K dataset. PyTorch code and checkpoints can be found at https://github.com/Hao840/OFAKD.

Recent years have witnessed the great success of vision transformer (ViT), which has achieved state-of-the-art performance on multiple computer vision benchmarks. However, ViT models suffer from vast amounts of parameters and high computation cost, leading to difficult deployment on resource-constrained edge devices. Existing solutions mostly compress ViT models to a compact model but still cannot achieve real-time inference. To tackle this issue, we propose to explore the divisibility of transformer structure, and decompose the large ViT into multiple small models for collaborative inference at edge devices. Our objective is to achieve fast and energy-efficient collaborative inference while maintaining comparable accuracy compared with large ViTs. To this end, we first propose a collaborative inference framework termed DeViT to facilitate edge deployment by decomposing large ViTs. Subsequently, we design a decomposition-and-ensemble algorithm based on knowledge distillation, termed DEKD, to fuse multiple small decomposed models while dramatically reducing communication overheads, and handle heterogeneous models by developing a feature matching module to promote the imitations of decomposed models from the large ViT. Extensive experiments for three representative ViT backbones on four widely-used datasets demonstrate our method achieves efficient collaborative inference for ViTs and outperforms existing lightweight ViTs, striking a good trade-off between efficiency and accuracy. For example, our DeViTs improves end-to-end latency by 2.89$\times$ with only 1.65% accuracy sacrifice using CIFAR-100 compared to the large ViT, ViT-L/16, on the GPU server. DeDeiTs surpasses the recent efficient ViT, MobileViT-S, by 3.54% in accuracy on ImageNet-1K, while running 1.72$\times$ faster and requiring 55.28% lower energy consumption on the edge device., Comment: Accepted by IEEE Transactions on Mobile Computing

Recently, the compression and deployment of powerful deep neural networks (DNNs) on resource-limited edge devices to provide intelligent services have become attractive tasks. Although knowledge distillation (KD) is a feasible solution for compression, its requirement on the original dataset raises privacy concerns. In addition, it is common to integrate multiple pretrained models to achieve satisfactory performance. How to compress multiple models into a tiny model is challenging, especially when the original data are unavailable. To tackle this challenge, we propose a framework termed collaborative data-free knowledge distillation via multi-level feature sharing (CDFKD-MFS), which consists of a multi-header student module, an asymmetric adversarial data-free KD module, and an attention-based aggregation module. In this framework, the student model equipped with a multi-level feature-sharing structure learns from multiple teacher models and is trained together with a generator in an asymmetric adversarial manner. When some real samples are available, the attention module adaptively aggregates predictions of the student headers, which can further improve performance. We conduct extensive experiments on three popular computer visual datasets. In particular, compared with the most competitive alternative, the accuracy of the proposed framework is 1.18\% higher on the CIFAR-100 dataset, 1.67\% higher on the Caltech-101 dataset, and 2.99\% higher on the mini-ImageNet dataset.

Recently, deploying deep neural network (DNN) models via collaborative inference, which splits a pre-trained model into two parts and executes them on user equipment (UE) and edge server respectively, becomes attractive. However, the large intermediate feature of DNN impedes flexible decoupling, and existing approaches either focus on the single UE scenario or simply define tasks considering the required CPU cycles, but ignore the indivisibility of a single DNN layer. In this paper, we study the multi-agent collaborative inference scenario, where a single edge server coordinates the inference of multiple UEs. Our goal is to achieve fast and energy-efficient inference for all UEs. To achieve this goal, we first design a lightweight autoencoder-based method to compress the large intermediate feature. Then we define tasks according to the inference overhead of DNNs and formulate the problem as a Markov decision process (MDP). Finally, we propose a multi-agent hybrid proximal policy optimization (MAHPPO) algorithm to solve the optimization problem with a hybrid action space. We conduct extensive experiments with different types of networks, and the results show that our method can reduce up to 56\% of inference latency and save up to 72\% of energy consumption.

In the past few years, transformers have achieved promising performances on various computer vision tasks. Unfortunately, the immense inference overhead of most existing vision transformers withholds their from being deployed on edge devices such as cell phones and smart watches. Knowledge distillation is a widely used paradigm for compressing cumbersome architectures via transferring information to a compact student. However, most of them are designed for convolutional neural networks (CNNs), which do not fully investigate the character of vision transformer (ViT). In this paper, we utilize the patch-level information and propose a fine-grained manifold distillation method. Specifically, we train a tiny student model to match a pre-trained teacher model in the patch-level manifold space. Then, we decouple the manifold matching loss into three terms with careful design to further reduce the computational costs for the patch relationship. Equipped with the proposed method, a DeiT-Tiny model containing 5M parameters achieves 76.5% top-1 accuracy on ImageNet-1k, which is +2.0% higher than previous distillation approaches. Transfer learning results on other classification benchmarks and downstream vision tasks also demonstrate the superiority of our method over the state-of-the-art algorithms.

This thesis focuses on the determinants of mergers and acquisitions (M&As) in the US and international market. To begin with, this thesis investigates whether the mega-mergers tend to cluster by time and industry and what is the cause of mega-merger waves. This research finds strong support for capital liquidity theory by Harford (2005). In contrast to the conclusion of Harford (2005), the industry economic shock index is insignificant and does not have explanatory power in the start of mega-merger waves. Capital liquidity is clearly established as causing industry mega-merger waves to cluster in time. Further to this, the mis-valuation factors studied have only a fair explanatory power in predicting mega-merger waves, and they add only marginally to the predictive power of the capital liquidity theory. Furthermore, this thesis studies the relationship between state visits and cross-border merger and acquisition (M&A) activity. Based on 1,161 official political state visits paid by the head of 19 countries to 49 countries and 11,531 cross-border acquisitions, this research finds that corporations from visiting countries are more likely to acquire corporations in the countries hosting the visit. Domestic acquisitions in the host country or M&As with non-visiting countries are not elevated. Evidence from instrumental variable analysis points towards a causal effect of state visits on M&A activity. Further analysis shows that the elevated M&A activity originating from visiting countries can be attributed to business networking and a reduction in investment uncertainty and cultural barriers. In addition, this thesis further examines the relationship between political state visits and post-merger short- and long-term performance. This research finds that cross-border deals made during the visit year and the years after generate lower abnormal returns in the long- term than those in the years of non-visits. Cross-border deals during the visit year and years after generate

This thesis focuses on the determinants of mergers and acquisitions (M&As) in the US and international market. To begin with, this thesis investigates whether the mega-mergers tend to cluster by time and industry and what is the cause of mega-merger waves. This research finds strong support for capital liquidity theory by Harford (2005). In contrast to the conclusion of Harford (2005), the industry economic shock index is insignificant and does not have explanatory power in the start of mega-merger waves. Capital liquidity is clearly established as causing industry mega-merger waves to cluster in time. Further to this, the mis-valuation factors studied have only a fair explanatory power in predicting mega-merger waves, and they add only marginally to the predictive power of the capital liquidity theory. Furthermore, this thesis studies the relationship between state visits and cross-border merger and acquisition (M&A) activity. Based on 1,161 official political state visits paid by the head of 19 countries to 49 countries and 11,531 cross-border acquisitions, this research finds that corporations from visiting countries are more likely to acquire corporations in the countries hosting the visit. Domestic acquisitions in the host country or M&As with non-visiting countries are not elevated. Evidence from instrumental variable analysis points towards a causal effect of state visits on M&A activity. Further analysis shows that the elevated M&A activity originating from visiting countries can be attributed to business networking and a reduction in investment uncertainty and cultural barriers. In addition, this thesis further examines the relationship between political state visits and post-merger short- and long-term performance. This research finds that cross-border deals made during the visit year and the years after generate lower abnormal returns in the long- term than those in the years of non-visits. Cross-border deals during the visit year and years after generate

This thesis focuses on the determinants of mergers and acquisitions (M&As) in the US and international market. To begin with, this thesis investigates whether the mega-mergers tend to cluster by time and industry and what is the cause of mega-merger waves. This research finds strong support for capital liquidity theory by Harford (2005). In contrast to the conclusion of Harford (2005), the industry economic shock index is insignificant and does not have explanatory power in the start of mega-merger waves. Capital liquidity is clearly established as causing industry mega-merger waves to cluster in time. Further to this, the mis-valuation factors studied have only a fair explanatory power in predicting mega-merger waves, and they add only marginally to the predictive power of the capital liquidity theory. Furthermore, this thesis studies the relationship between state visits and cross-border merger and acquisition (M&A) activity. Based on 1,161 official political state visits paid by the head of 19 countries to 49 countries and 11,531 cross-border acquisitions, this research finds that corporations from visiting countries are more likely to acquire corporations in the countries hosting the visit. Domestic acquisitions in the host country or M&As with non-visiting countries are not elevated. Evidence from instrumental variable analysis points towards a causal effect of state visits on M&A activity. Further analysis shows that the elevated M&A activity originating from visiting countries can be attributed to business networking and a reduction in investment uncertainty and cultural barriers. In addition, this thesis further examines the relationship between political state visits and post-merger short- and long-term performance. This research finds that cross-border deals made during the visit year and the years after generate lower abnormal returns in the long- term than those in the years of non-visits. Cross-border deals during the visit year and years after generate

This thesis focuses on the determinants of mergers and acquisitions (M&As) in the US and international market. To begin with, this thesis investigates whether the mega-mergers tend to cluster by time and industry and what is the cause of mega-merger waves. This research finds strong support for capital liquidity theory by Harford (2005). In contrast to the conclusion of Harford (2005), the industry economic shock index is insignificant and does not have explanatory power in the start of mega-merger waves. Capital liquidity is clearly established as causing industry mega-merger waves to cluster in time. Further to this, the mis-valuation factors studied have only a fair explanatory power in predicting mega-merger waves, and they add only marginally to the predictive power of the capital liquidity theory. Furthermore, this thesis studies the relationship between state visits and cross-border merger and acquisition (M&A) activity. Based on 1,161 official political state visits paid by the head of 19 countries to 49 countries and 11,531 cross-border acquisitions, this research finds that corporations from visiting countries are more likely to acquire corporations in the countries hosting the visit. Domestic acquisitions in the host country or M&As with non-visiting countries are not elevated. Evidence from instrumental variable analysis points towards a causal effect of state visits on M&A activity. Further analysis shows that the elevated M&A activity originating from visiting countries can be attributed to business networking and a reduction in investment uncertainty and cultural barriers. In addition, this thesis further examines the relationship between political state visits and post-merger short- and long-term performance. This research finds that cross-border deals made during the visit year and the years after generate lower abnormal returns in the long- term than those in the years of non-visits. Cross-border deals during the visit year and years after generate