Bipedal robots have received much attention because of the variety of motion maneuvers that they can produce, and the many applications they have in various areas including rehabilitation. One of these motion maneuvers is walking. In this study, we presented a framework for the trajectory optimization of a 5-link (planar) Biped Robot using hybrid optimization. The walking is modeled with two phases of single-stance (support) phase and the collision phase. The dynamic equations of the robot in each phase are extracted by the Lagrange method. It is assumed that the robot heel strike to the ground is full plastic. The gait is optimized with a method called hybrid optimization. The objective function of this problem is considered to be the integral of torque-squared along the trajectory, and also various constraints such as zero dynamics are satisfied without any approximation. Furthermore, in a new framework, there is presented a constraint called impact invariance, which ensures the periodicity of the time-varying trajectories. On the other hand, other constraints provide better and more human-like movement.
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The importance of humanoid robots in today's world is undeniable, one of the most important features of humanoid robots is the ability to maneuver in environments such as stairs that other robots can not easily cross. A suitable algorithm to generate the path for the bipedal robot to climb is very important. In this paper, an optimization-based method to generate an optimal stairway for under-actuated bipedal robots without an ankle actuator is presented. The generated paths are based on zero and non-zero dynamics of the problem, and according to the satisfaction of the zero dynamics constraint in the problem, tracking the path is possible, in other words, the problem can be dynamically feasible. The optimization method used in the problem is a gradient-based method that has a suitable number of function evaluations for computational processing. This method can also be utilized to go down the stairs.
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It does not matter whether it is a job interview with Tech Giants, Wall Street firms, or a small startup; all candidates want to demonstrate their best selves or even present themselves better than they really are. Meanwhile, recruiters want to know the candidates' authentic selves and detect soft skills that prove an expert candidate would be a great fit in any company. Recruiters worldwide usually struggle to find employees with the highest level of these skills. Digital footprints can assist recruiters in this process by providing candidates' unique set of online activities, while social media delivers one of the largest digital footprints to track people. In this study, for the first time, we show that a wide range of behavioral competencies consisting of 16 in-demand soft skills can be automatically predicted from Instagram profiles based on the following lists and other quantitative features using machine learning algorithms. We also provide predictions on Big Five personality traits. Models were built based on a sample of 400 Iranian volunteer users who answered an online questionnaire and provided their Instagram usernames which allowed us to crawl the public profiles. We applied several machine learning algorithms to the uniformed data. Deep learning models mostly outperformed by demonstrating 70% and 69% average Accuracy in two-level and three-level classifications respectively. Creating a large pool of people with the highest level of soft skills, and making more accurate evaluations of job candidates is possible with the application of AI on social media user-generated data.
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National Association of Securities Dealers Automated Quotations(NASDAQ) is an American stock exchange based. It is one of the most valuable stock economic indices in the world and is located in New York City \cite{pagano2008quality}. The volatility of the stock market and the influence of economic indicators such as crude oil, gold, and the dollar in the stock market, and NASDAQ shares are also affected and have a volatile and chaotic nature \cite{firouzjaee2022lstm}.In this article, we have examined the effect of oil, dollar, gold, and the volatility of the stock market in the economic market, and then we have also examined the effect of these indicators on NASDAQ stocks. Then we started to analyze the impact of the feedback on the past prices of NASDAQ stocks and its impact on the current price. Using PCA and Linear Regression algorithm, we have designed an optimal dynamic learning experience for modeling these stocks. The results obtained from the quantitative analysis are consistent with the results of the qualitative analysis of economic studies, and the modeling done with the optimal dynamic experience of machine learning justifies the current price of NASDAQ shares.
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Knowledge Distillation (KD) has been extensively used for natural language understanding (NLU) tasks to improve a small model's (a student) generalization by transferring the knowledge from a larger model (a teacher). Although KD methods achieve state-of-the-art performance in numerous settings, they suffer from several problems limiting their performance. It is shown in the literature that the capacity gap between the teacher and the student networks can make KD ineffective. Additionally, existing KD techniques do not mitigate the noise in the teacher's output: modeling the noisy behaviour of the teacher can distract the student from learning more useful features. We propose a new KD method that addresses these problems and facilitates the training compared to previous techniques. Inspired by continuation optimization, we design a training procedure that optimizes the highly non-convex KD objective by starting with the smoothed version of this objective and making it more complex as the training proceeds. Our method (Continuation-KD) achieves state-of-the-art performance across various compact architectures on NLU (GLUE benchmark) and computer vision tasks (CIFAR-10 and CIFAR-100).
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The classification of sleep stages plays a crucial role in understanding and diagnosing sleep pathophysiology. Sleep stage scoring relies heavily on visual inspection by an expert that is time consuming and subjective procedure. Recently, deep learning neural network approaches have been leveraged to develop a generalized automated sleep staging and account for shifts in distributions that may be caused by inherent inter/intra-subject variability, heterogeneity across datasets, and different recording environments. However, these networks ignore the connections among brain regions, and disregard the sequential connections between temporally adjacent sleep epochs. To address these issues, this work proposes an adaptive product graph learning-based graph convolutional network, named ProductGraphSleepNet, for learning joint spatio-temporal graphs along with a bidirectional gated recurrent unit and a modified graph attention network to capture the attentive dynamics of sleep stage transitions. Evaluation on two public databases: the Montreal Archive of Sleep Studies (MASS) SS3; and the SleepEDF, which contain full night polysomnography recordings of 62 and 20 healthy subjects, respectively, demonstrates performance comparable to the state-of-the-art (Accuracy: 0.867;0.838, F1-score: 0.818;0.774 and Kappa: 0.802;0.775, on each database respectively). More importantly, the proposed network makes it possible for clinicians to comprehend and interpret the learned connectivity graphs for sleep stages.
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Graph Learning (GL) is at the core of inference and analysis of connections in data mining and machine learning (ML). By observing a dataset of graph signals, and considering specific assumptions, Graph Signal Processing (GSP) tools can provide practical constraints in the GL approach. One applicable constraint can infer a graph with desired frequency signatures, i.e., spectral templates. However, a severe computational burden is a challenging barrier, especially for inference from high-dimensional graph signals. To address this issue and in the case of the underlying graph having graph product structure, we propose learning product (high dimensional) graphs from product spectral templates with significantly reduced complexity rather than learning them directly from high-dimensional graph signals, which, to the best of our knowledge, has not been addressed in the related areas. In contrast to the rare current approaches, our approach can learn all types of product graphs (with more than two graphs) without knowing the type of graph products and has fewer parameters. Experimental results on both the synthetic and real-world data, i.e., brain signal analysis and multi-view object images, illustrate explainable and meaningful factor graphs supported by expert-related research, as well as outperforming the rare current restricted approaches.
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社区检测是网络科学中的经典问题,在各个领域都有广泛的应用。最常用的方法是设计算法,旨在最大程度地跨越网络分配到社区中的不同方式,以最大化效用函数,模块化。尽管它们的名称和设计理念,但当前的模块化最大化算法通常无法最大化模块化或保证与最佳解决方案的任何接近。我们提出了Bayan算法,该算法与现有方法不同,该算法返回网络分区,以确保最佳或靠近最佳解决方案。 Bayan算法的核心是一种分支和切割方案,该方案解决了模块化最大化问题的稀疏整数编程公式,以最佳或在一个因素内近似它。我们使用合成和真实网络分析了Bayan对22种现有算法的性能。通过广泛的实验,我们不仅在最大化模块化方面展示了Bayan的独特能力,而且更重要的是在准确检索地面真实群落方面。 Bayan的比较性能水平在数据(图)生成过程中噪声量的变化上保持稳定。 Bayan作为确切的模块化最大化算法的性能也揭示了在社区准确检索中最大模块化分区的理论能力限制。总体而言,我们的分析指出,通过精确(近似)最大化的网络中的模块化(近似$ \ sim10^3 $边缘(和较大的网络)),BAYAN是对社区进行方法基础检测的合适选择。图形优化和整数编程的前瞻性进步可以进一步推动这些限制。
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基于尺寸的生物颗粒/细胞分离对于外泌体和DNA分离等应用的多种生物医学处理步骤至关重要。这种微流体设备的设计和改进是最佳回答生产均质最终结果的需求的挑战。确定性的横向位移(DLD)利用了类似的原则,该原理在多年来引起了广泛的关注。但是,缺乏对粒子轨迹及其诱导模式的预测性理解,使设计DLD设备成为迭代过程。因此,本文研究了一个快速的多功能设计自动化平台来解决此问题。为此,采用了卷积和人工神经网络来学习各种DLD配置的速度场和临界直径。后来,将这些网络与多目标进化算法结合使用,以构建自动化工具。在确保神经网络的准确性之后,对开发的工具进行了12个关键条件测试。达到施加的条件,自动化组件可靠地执行,误差小于4%。此外,该工具可以推广到其他基于现场的问题,并且由于神经网络是该方法不可或缺的一部分,因此它可以为类似物理学进行转移学习。本研究中生成和使用的所有代码与预先训练的神经网络模型都可以在https://github.com/hoseynaamiri/dldnn上获得。
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我们研究数据所有者/卖方的数据搜索者/买家的数据。假设特定的实用程序指标(例如验证集中的测试准确性)在实践中可能不存在,则通常针对特定任务进行数据估值。在这项工作中,我们专注于任务不足的数据评估,而无需任何验证要求。数据购买者可以访问有限数量的数据(可以公开使用),并从数据销售商那里寻求更多数据示例。我们将问题提出,以估计卖方在买方可用的基线数据方面数据的统计属性差异。我们通过衡量买方数据的多样性和相关性来捕获这些统计差异;我们在不要求原始数据的情况下向卖方估算这些措施。我们通过提出的方法设计查询,以使卖方对买方的原始数据视而不见,并且不知道对查询的响应进行响应,以获得多样性和相关性权衡的期望结果。我们将通过对真实的广泛实验进行展示。拟议估计值的表格和图像数据集捕获了买方卖方数据的多样性和相关性。
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