最佳定价,即确定最大限度地提高给定产品的利润或收入的价格水平,是零售业的重要任务。要选择这样的数量,请先估计产品需求的价格弹性。由于混淆效果和价格内限性,回归方法通常无法恢复这些弹性。因此,通常需要随机实验。然而,例如,弹性可以是高度异构的,这取决于商店的位置。随着随机化经常发生在市级,标准差异差异方法也可能失败。可能的解决方案是基于根据从人工对照构成的治疗方法测量处理对单个(或仅几个)处理单元的影响的方法。例如,对于治疗组中的每个城市,可以从未处理的位置构成反事实。在本文中,我们应用了一种新的高维统计方法,以衡量价格变化对巴西主要零售商的日常销售的影响。所提出的方法结合了主成分(因子)和稀疏回归,导致一种称为因子调整的正规化方法的方法(\ TextTt {FarmTraTeat})。数据包括每日五种不同产品的日常销售和价格,超过400多名市。审议的产品属于\ emph {甜蜜和糖果}类别和实验已经在2016年和2017年进行。我们的结果证实了高度异质性的假设,从而产生了与独特的市政当局的不同定价策略。
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完全自主移动机器人的现实部署取决于能够处理动态环境的强大的大满贯(同时本地化和映射)系统,其中对象在机器人的前面移动以及不断变化的环境,在此之后移动或更换对象。机器人已经绘制了现场。本文介绍了更换式SLAM,这是一种在动态和不断变化的环境中强大的视觉猛烈抨击的方法。这是通过使用与长期数据关联算法结合的贝叶斯过滤器来实现的。此外,它采用了一种有效的算法,用于基于对象检测的动态关键点过滤,该对象检测正确识别了不动态的边界框中的特征,从而阻止了可能导致轨道丢失的功能的耗竭。此外,开发了一个新的数据集,其中包含RGB-D数据,专门针对评估对象级别的变化环境,称为PUC-USP数据集。使用移动机器人,RGB-D摄像头和运动捕获系统创建了六个序列。这些序列旨在捕获可能导致跟踪故障或地图损坏的不同情况。据我们所知,更换 - 峰是第一个对动态和不断变化的环境既有坚固耐用的视觉大满贯系统,又不假设给定的相机姿势或已知地图,也能够实时运行。使用基准数据集对所提出的方法进行了评估,并将其与其他最先进的方法进行了比较,证明是高度准确的。
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本文提出了一种新的加速马尔可夫链蒙特卡洛(MCMC)方法,以在成像逆问题中有效地执行贝叶斯计算。所提出的方法源自兰格文扩散过程,并源于紧密整合两个最先进的近端Langevin MCMC采样器,SK-ROCK和SPLIST GIBBS采样(SGS),它们采用明显不同的策略来提高收敛速度。更确切地说,我们在Langevin扩散过程的水平上展示了如何集成基于随机的Runge-Kutta-chebyshev扩散的近端SK-ROCK采样器,该采样器具有模型增强和放松策略,可用于扩散以牺牲渐近偏差为代价加快贝叶斯计算的速度。这导致了一种新的,更快的近端SK-ROCK采样器,将原始SK-Rock采样器的加速质量与增强和放松的计算益处相结合。此外,我们建议将增强和放松的模型视为目标模型的近似值,而是将放松定位在偏见 - 差异权衡中,而是建议将增强和放松的模型视为目标模型的概括。然后,这使我们能够仔细校准放松量,以同时提高模型的准确性(通过模型证据衡量)和采样器的收敛速度。为了实现这一目标,我们得出了一种经验性的贝叶斯方法,可以通过最大的边际似然估计自动估计最佳的松弛量。通过与图像脱毛和内化相关的一系列数值实验,以及与艺术状态的替代方法进行比较,证明了所提出的方法。
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Delimiting salt inclusions from migrated images is a time-consuming activity that relies on highly human-curated analysis and is subject to interpretation errors or limitations of the methods available. We propose to use migrated images produced from an inaccurate velocity model (with a reasonable approximation of sediment velocity, but without salt inclusions) to predict the correct salt inclusions shape using a Convolutional Neural Network (CNN). Our approach relies on subsurface Common Image Gathers to focus the sediments' reflections around the zero offset and to spread the energy of salt reflections over large offsets. Using synthetic data, we trained a U-Net to use common-offset subsurface images as input channels for the CNN and the correct salt-masks as network output. The network learned to predict the salt inclusions masks with high accuracy; moreover, it also performed well when applied to synthetic benchmark data sets that were not previously introduced. Our training process tuned the U-Net to successfully learn the shape of complex salt bodies from partially focused subsurface offset images.
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在这项工作中,我们提出了一种基于从Marmoset猴的大脑收集的局部场潜在数据,提出了与帕金森病相关的新生物物理计算模型。帕金森病是一种神经退行性疾病,与大量NIGRA PARSCACTCA的多巴胺能神经元的死亡有关,这影响了大脑基底神经节 - 丘脑 - 皮质神经元电路的正常动态。尽管存在多种疾病的机制,但仍然缺少这些机制和分子发病机制的完整描述,仍然没有治愈。为了解决这种差距,已经提出了类似于动物模型中发现的神经生物学方面的计算模型。在我们的模型中,我们执行了一种数据驱动方法,其中使用差分演变优化了一组生物学限制参数。进化模型成功地类似于来自健康和Parkinsonian Marmoset脑数据的单神经元均值射击和局部场势的光谱签名。据我们所知,这是帕金森病的第一个基于来自Marmoset Monkeys的七个脑区域的同时电生理学记录的第一个计算模型。结果表明,该拟议的模型可以促进PD机制的调查,并支持可以表明新疗法的技术的发展。它还可以应用于其他计算神经科学问题,其中可以使用生物数据来适应大规模模型的脑电路。
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There are multiple scales of abstraction from which we can describe the same image, depending on whether we are focusing on fine-grained details or a more global attribute of the image. In brain mapping, learning to automatically parse images to build representations of both small-scale features (e.g., the presence of cells or blood vessels) and global properties of an image (e.g., which brain region the image comes from) is a crucial and open challenge. However, most existing datasets and benchmarks for neuroanatomy consider only a single downstream task at a time. To bridge this gap, we introduce a new dataset, annotations, and multiple downstream tasks that provide diverse ways to readout information about brain structure and architecture from the same image. Our multi-task neuroimaging benchmark (MTNeuro) is built on volumetric, micrometer-resolution X-ray microtomography images spanning a large thalamocortical section of mouse brain, encompassing multiple cortical and subcortical regions. We generated a number of different prediction challenges and evaluated several supervised and self-supervised models for brain-region prediction and pixel-level semantic segmentation of microstructures. Our experiments not only highlight the rich heterogeneity of this dataset, but also provide insights into how self-supervised approaches can be used to learn representations that capture multiple attributes of a single image and perform well on a variety of downstream tasks. Datasets, code, and pre-trained baseline models are provided at: https://mtneuro.github.io/ .
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The purpose of this work was to tackle practical issues which arise when using a tendon-driven robotic manipulator with a long, passive, flexible proximal section in medical applications. A separable robot which overcomes difficulties in actuation and sterilization is introduced, in which the body containing the electronics is reusable and the remainder is disposable. A control input which resolves the redundancy in the kinematics and a physical interpretation of this redundancy are provided. The effect of a static change in the proximal section angle on bending angle error was explored under four testing conditions for a sinusoidal input. Bending angle error increased for increasing proximal section angle for all testing conditions with an average error reduction of 41.48% for retension, 4.28% for hysteresis, and 52.35% for re-tension + hysteresis compensation relative to the baseline case. Two major sources of error in tracking the bending angle were identified: time delay from hysteresis and DC offset from the proximal section angle. Examination of these error sources revealed that the simple hysteresis compensation was most effective for removing time delay and re-tension compensation for removing DC offset, which was the primary source of increasing error. The re-tension compensation was also tested for dynamic changes in the proximal section and reduced error in the final configuration of the tip by 89.14% relative to the baseline case.
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We introduce a novel framework to track multiple objects in overhead camera videos for airport checkpoint security scenarios where targets correspond to passengers and their baggage items. We propose a Self-Supervised Learning (SSL) technique to provide the model information about instance segmentation uncertainty from overhead images. Our SSL approach improves object detection by employing a test-time data augmentation and a regression-based, rotation-invariant pseudo-label refinement technique. Our pseudo-label generation method provides multiple geometrically-transformed images as inputs to a Convolutional Neural Network (CNN), regresses the augmented detections generated by the network to reduce localization errors, and then clusters them using the mean-shift algorithm. The self-supervised detector model is used in a single-camera tracking algorithm to generate temporal identifiers for the targets. Our method also incorporates a multi-view trajectory association mechanism to maintain consistent temporal identifiers as passengers travel across camera views. An evaluation of detection, tracking, and association performances on videos obtained from multiple overhead cameras in a realistic airport checkpoint environment demonstrates the effectiveness of the proposed approach. Our results show that self-supervision improves object detection accuracy by up to $42\%$ without increasing the inference time of the model. Our multi-camera association method achieves up to $89\%$ multi-object tracking accuracy with an average computation time of less than $15$ ms.
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Compliance in actuation has been exploited to generate highly dynamic maneuvers such as throwing that take advantage of the potential energy stored in joint springs. However, the energy storage and release could not be well-timed yet. On the contrary, for multi-link systems, the natural system dynamics might even work against the actual goal. With the introduction of variable stiffness actuators, this problem has been partially addressed. With a suitable optimal control strategy, the approximate decoupling of the motor from the link can be achieved to maximize the energy transfer into the distal link prior to launch. However, such continuous stiffness variation is complex and typically leads to oscillatory swing-up motions instead of clear launch sequences. To circumvent this issue, we investigate decoupling for speed maximization with a dedicated novel actuator concept denoted Bi-Stiffness Actuation. With this, it is possible to fully decouple the link from the joint mechanism by a switch-and-hold clutch and simultaneously keep the elastic energy stored. We show that with this novel paradigm, it is not only possible to reach the same optimal performance as with power-equivalent variable stiffness actuation, but even directly control the energy transfer timing. This is a major step forward compared to previous optimal control approaches, which rely on optimizing the full time-series control input.
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The previous fine-grained datasets mainly focus on classification and are often captured in a controlled setup, with the camera focusing on the objects. We introduce the first Fine-Grained Vehicle Detection (FGVD) dataset in the wild, captured from a moving camera mounted on a car. It contains 5502 scene images with 210 unique fine-grained labels of multiple vehicle types organized in a three-level hierarchy. While previous classification datasets also include makes for different kinds of cars, the FGVD dataset introduces new class labels for categorizing two-wheelers, autorickshaws, and trucks. The FGVD dataset is challenging as it has vehicles in complex traffic scenarios with intra-class and inter-class variations in types, scale, pose, occlusion, and lighting conditions. The current object detectors like yolov5 and faster RCNN perform poorly on our dataset due to a lack of hierarchical modeling. Along with providing baseline results for existing object detectors on FGVD Dataset, we also present the results of a combination of an existing detector and the recent Hierarchical Residual Network (HRN) classifier for the FGVD task. Finally, we show that FGVD vehicle images are the most challenging to classify among the fine-grained datasets.
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