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Improved Q-learning for Energy Management in a Grid-tied PV Microgrid 用于并网光伏微电网能量管理的改进Q学习
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432896
Erick O. Arwa;Komla A. Folly
This paper proposes an improved Q-learning method to obtain near-optimal schedules for grid and battery power in a grid-connected electric vehicle charging station for a 24-hour horizon. The charging station is supplied by a solar PV generator with a backup from the utility grid. The grid tariff model is dynamic in line with the smart grid paradigm. First, the mathematical formulation of the problem is developed highlighting each of the cost components considered including battery degradation cost and the real-time tariff for grid power purchase cost. The problem is then formulated as a Markov Decision Process (MDP), i.e., defining each of the parts of a reinforcement learning environment for the charging station’s operation. The MDP is solved using the improved Q-learning algorithm proposed in this paper and the results are compared with the conventional Q-learning method. Specifically, the paper proposes to modify the action-space of a Q-learning algorithm so that each state has just the list of actions that meet a power balance constraint. The Q-table updates are done asynchronously, i.e., the agent does not sweep through the entire state-space in each episode. Simulation results show that the improved Q-learning algorithm returns a 14% lower global cost and achieves higher total rewards than the conventional Q-learning method. Furthermore, it is shown that the improved Q-learning method is more stable in terms of the sensitivity to the learning rate than the conventional Q-learning.
本文提出了一种改进的Q学习方法,以获得24小时内并网电动汽车充电站电网和电池功率的接近最优调度。充电站由太阳能光伏发电机供电,并由公用电网提供备用。电网电价模型是动态的,符合智能电网模式。首先,开发了该问题的数学公式,突出了所考虑的每个成本组成部分,包括电池退化成本和电网购电成本的实时电价。然后,该问题被公式化为马尔可夫决策过程(MDP),即,为充电站的操作定义强化学习环境的每个部分。使用本文提出的改进的Q学习算法求解MDP,并将结果与传统的Q学习方法进行了比较。具体来说,本文提出修改Q学习算法的动作空间,使每个状态只有满足功率平衡约束的动作列表。Q表更新是异步完成的,即代理不会在每个事件中扫过整个状态空间。仿真结果表明,与传统的Q学习方法相比,改进的Q学习算法的全局成本降低了14%,并获得了更高的总回报。此外,研究表明,改进的Q学习方法在对学习率的敏感性方面比传统的Q学习更稳定。
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引用次数: 4
Copyright 版权
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432891
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引用次数: 0
Iterative Soft-Input Soft-Output Bit-Level Reed-Solomon Decoder Based on Information Set Decoding 基于信息集译码的迭代软输入软输出位级Reed-Solomon译码器
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432893
Yuval Genga;Olutayo O. Oyerinde;Jaco Versfeld
In this paper, a bit-level decoder is presented for soft-input soft-output iterative decoding of Reed-Solomon (RS) codes. The main aim for the development of the proposed algorithm is to reduce the complexity of the decoding process, while yielding a relatively good error correction performance, for the efficient use of RS codes. The decoder utilises information set decoding techniques to reduce the computational complexity cost by lowering the iterative convergence rate during the decoding process. As opposed to most iterative bit-level soft-decision decoders for RS codes, the proposed algorithm is also able to avoid the use of belief propagation in the iterative decoding of the soft bit information, which also contributes to the reduction in the computational complexity cost of the decoding process. The performance of the proposed decoder is investigated when applied to short RS codes. The error correction simulations show the proposed algorithm is able to yield a similar performance to that of the Adaptive Belief Propagation (ABP) algorithm, while being a less complex decoder.
提出了一种用于RS码软输入软输出迭代译码的位级解码器。开发该算法的主要目的是为了降低解码过程的复杂性,同时产生相对较好的纠错性能,以便有效地使用RS码。该译码器利用信息集译码技术,通过降低译码过程中的迭代收敛速度来降低计算复杂度。与大多数RS码的迭代位级软判决译码器不同,该算法在软位信息的迭代译码过程中避免了信念传播的使用,这也有助于降低译码过程的计算复杂度成本。研究了该解码器在短RS码中的性能。误差校正仿真结果表明,该算法具有与自适应信念传播(ABP)算法相似的性能,且解码器复杂度较低。
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引用次数: 1
Ear-based biometric authentication through the detection of prominent contours 基于耳朵的生物特征认证,通过检测突出的轮廓
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432897
Aviwe Kohlakala;Johannes Coetzer
In this paper novel semi-automated and fully automated ear-based biometric authentication systems are proposed. The region of interest (ROI) is manually specified and automatically detected within the context of the semi-automated and fully automated systems, respectively. The automatic detection of the ROI is facilitated by a convolutional neural network (CNN) and morphological postprocessing. The CNN classifies sub-images of the ear in question as either foreground (part of the ear shell) or background (homogeneous skin, hair or jewellery). Prominent contours associated with the folds of the ear shell are detected within the ROI. The discrete Radon transform (DRT) is subsequently applied to the resulting binary contour image for the purpose of feature extraction. Feature matching is achieved by implementing an Euclidean distance measure. A ranking verifier is constructed for the purpose of authentication. In this study experiments are conducted on two independent ear databases, that is (1) the Mathematical Analysis of Images (AMI) ear database and (2) the Indian Institute of Technology (IIT) Delhi ear database. The results are encouraging. Within the context of the proposed semi-automated system, accuracies of 99.20% and 96.06% are reported for the AMI and IIT Delhi ear databases respectively.
摘要——本文提出了一种新的基于耳朵的半自动和全自动生物识别认证系统。感兴趣区域(ROI)分别在半自动化和全自动化系统的上下文中手动指定和自动检测。卷积神经网络(CNN)和形态学后处理促进了ROI的自动检测。美国有线电视新闻网将有问题的耳朵的子图像分类为前景(耳朵外壳的一部分)或背景(同质的皮肤、头发或珠宝)。在ROI内检测到与耳壳褶皱相关的突出轮廓。随后将离散Radon变换(DRT)应用于生成的二值轮廓图像,用于特征提取。特征匹配是通过实现欧几里得距离度量来实现的。为了进行身份验证,构建了一个排名验证器。在本研究中,在两个独立的耳朵数据库上进行了实验,即(1)图像数学分析(AMI)耳朵数据库和(2)印度理工学院(IIT)德里耳朵数据库。结果令人鼓舞。在所提出的半自动化系统的背景下,AMI和IIT德里耳数据库的准确率分别为99.20%和96.06%。
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引用次数: 9
Effect of Graphite Precursor Flake Size on Energy Storage Capabilities of Graphene Oxide Supercapacitors 石墨前驱体薄片尺寸对氧化石墨烯超级电容器储能性能的影响
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432895
S. Perumal;A.L.L. Jarvis;M.Z. Gaffoor
In this research supercapacitors were fabricated using graphene oxide (GO) as the electrode material. GO was synthesized using natural graphite precursor with varying flake sizes. GO was characterized by High-Resolution Transmission Electron Microscopy (HRTEM), Elemental Analysis, Fourier Transform Infrared (FTIR) spectroscopy and Raman spectroscopy. Cyclic voltammetry was carried out at different scan rates to determine the specific capacitance and energy density of the electrode material. An increase in specific capacitance was seen with an increase in graphite precursor flake size. A specific capacitance and energy density of 204.22 F.g−1 and 102.11 kJ.kg−1 respectively at scan rate 10 mV.s−1 was obtained for the GO sample synthesized from graphite precursor with an average particle size of 0.45 mm. This sample also had the highest specific capacitance for all scan rates.
本研究以氧化石墨烯(GO)为电极材料制备了超级电容器。采用不同薄片尺寸的天然石墨前驱体合成了GO。采用高分辨透射电子显微镜(HRTEM)、元素分析、傅立叶变换红外光谱(FTIR)和拉曼光谱对GO进行了表征。在不同的扫描速率下进行循环伏安法,以确定电极材料的比电容和能量密度。比电容随着石墨前体薄片尺寸的增加而增加。由平均粒径为0.45 mm的石墨前驱体合成的GO样品在扫描速率为10 mV.s−1时获得了204.22 F.g−1和102.11 kJ.kg−1的比电容和能量密度。该样品在所有扫描速率下也具有最高的比电容。
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引用次数: 2
Editors and Reviewers 编辑和审稿人
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432890
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引用次数: 0
Guest Editorial: SAUPEC/RobMech/PRASA 2020 客座编辑:SAUPEC/RobMech/PRASA 2020
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432894
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引用次数: 0
Class-Selective Mini-Batching and Multitask Learning for Visual Relationship Recognition 用于视觉关系识别的类选择小批量和多任务学习
IF 1.4 Pub Date : 2021-03-17 DOI: 10.23919/SAIEE.2021.9432898
S. Josias;W. Brink
An image can be described by the objects within it, and interactions between those objects. A pair of object labels together with an interaction label is known as a visual relationship, and is represented as a triplet of the form (subject, predicate, object). Recognising visual relationships in images is a challenging task, owing to the combinatorially large number of possible relationship triplets, which leads to an extreme multiclass classification problem. In addition, the distribution of visual relationships in a dataset tends to be long-tailed, i.e. most triplets occur rarely compared to a small number of dominating triplets. Three strategies to address these issues are investigated. Firstly, instead of predicting the full triplet, models can be trained to predict each of the three elements separately. Secondly a multitask learning strategy is investigated, where shared network parameters are used to perform the three separate predictions. Thirdly, a class-selective mini-batch construction strategy is used to expose the network to more of the rare classes during training. Experiments demonstrate that class-selective mini-batch construction can improve performance on classes in the long tail of the data distribution, possibly at the expense of accuracy on the small number of dominating classes. It is also found that a multitask model neither improves nor impedes performance in any significant way, but that its smaller size may be beneficial. In an effort to better understand the behaviour of the various models, a novel evaluation approach for visual relationship recognition is introduced. We conclude that the use of semantics can be helpful in the modelling and evaluation process.
图像可以通过图像中的物体以及这些物体之间的相互作用来描述。一对对象标签和一个交互标签一起被称为视觉关系,并以三元组(主语、谓语、宾语)的形式表示。识别图像中的视觉关系是一项具有挑战性的任务,因为组合大量可能的关系三元组,这导致了极端的多类分类问题。此外,数据集中视觉关系的分布往往是长尾的,即与少数占主导地位的三元组相比,大多数三元组很少出现。研究了解决这些问题的三种策略。首先,可以训练模型分别预测三个元素,而不是预测完整的三元组。其次,研究了一种多任务学习策略,其中使用共享网络参数来执行三个独立的预测。第三,采用类选择性小批量构建策略,使网络在训练过程中接触到更多的稀有类。实验表明,类选择性小批构造可以提高数据分布长尾中类的性能,但可能以牺牲少量主导类的准确性为代价。研究还发现,多任务模型既不会以任何显著的方式提高也不会阻碍性能,但其较小的尺寸可能是有益的。为了更好地理解各种模型的行为,引入了一种新的视觉关系识别评估方法。我们得出结论,语义学的使用在建模和评估过程中是有帮助的。
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引用次数: 0
Investigative analysis of channel selection algorithms in cooperative spectrum sensing in cognitive radio networks 认知无线电网络中协作频谱感知信道选择算法的研究分析
IF 1.4 Pub Date : 2021-01-29 DOI: 10.23919/SAIEE.2021.9340532
J. Tlouyamma;M. Velempini
The proliferation of wireless mobile devices has led to a number of challenges in mobile data communication. The world is experiencinganincreasingusage of finite spectrum bands for social media and other data communication services. It is due to this high usage that the Federal Communications Commission(FCC) sought to open up some spectrum bands to be used opportunistically by secondary users (SUs). However, the coexistence of Primary Users (PUs) and SUs may cause interference which leads to wastage of spectrum resources. This study investigates the impact of interferences between PUs and SUs. To ensure higher detection of PU signal, a cooperative rule was used to decide which SU to share and makea final decision about the availability of the spectrum band. To maximize the throughput of SU, a maximum likelihood function was designed to reduce delays in searching for the next available channel for data transmission. To discover more transmission opportunities and ensuring that a good number of free channels are detected, a parallel sensing technique was employed. Matlabwas used to simulate and generate the results in a distributed cognitive radio environment. The proposed extended generalizedpredictive channel selection algorithm (EXGPCSA) outperformed otherschemes in literature in terms of throughput, service timeandprobability of detection.
无线移动设备的激增给移动数据通信带来了许多挑战。世界正经历着社交媒体和其他数据通信服务对有限频带的日益使用。正是由于这种高使用率,联邦通信委员会(FCC)试图开放一些频段供二次用户(SU)机会主义地使用。然而,主用户(PU)和SU的共存可能会导致干扰,从而导致频谱资源的浪费。本研究调查了PU和SU之间干扰的影响。为了确保对PU信号进行更高的检测,使用合作规则来决定共享哪个SU,并对频带的可用性做出最终决定。为了最大化SU的吞吐量,设计了一个最大似然函数来减少搜索下一个可用信道进行数据传输的延迟。为了发现更多的传输机会并确保检测到大量的空闲信道,采用了并行传感技术。Matlab用于在分布式认知无线电环境中模拟和生成结果。所提出的扩展广义预测信道选择算法(EXGPCSA)在吞吐量、服务时间和检测概率方面优于文献中的其他方案。
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引用次数: 6
Detection of Bryde's whale short pulse calls using time domain features with hidden Markov models 利用时域特征和隐马尔可夫模型检测布氏鲸短脉冲叫声
IF 1.4 Pub Date : 2021-01-29 DOI: 10.23919/SAIEE.2021.9340533
Oluwaseyi P. Babalola;Ayinde M. Usman;Olayinka O. Ogundile;Daniel J. J. Versfeld
Passive acoustic monitoring (PAM) is generally usedto extract acoustic signals produced by cetaceans. However, the large data volume from the PAM process is better analyzed using an automated technique such as the hidden Markovmodels (HMM). In this paper, the HMM is used as a detection and classification technique due to its robustness and low time complexity. Nonetheless, certain parameters, such as the choice of features to be extracted from the signal, the frame duration, and the number of states affect the performance of the model. Theresults show that HMM exhibits best performances as the number of states increases with short frame duration. However, increasing the number of states creates more computational complexity in the model. The inshore Bryde's whales produce short pulse calls with distinct signal features, which are observable in the time-domain. Hence, a time-domain feature vector is utilized to reduce the complexity of the HMM. Simulation results also show that average power as a time-domain feature vector provides the best performance compared to other feature vectors for detecting the short pulse call of inshore Bryde's whales based on the HMM technique. More so, the extracted features such as the average power, mean, and zero-crossing rate, are combined to form a single 3-dimensional vector (PaMZ). The PaMZ-HMM shows improved performance and reduced complexity over existing feature extraction techniques such as Mel-scale frequency cepstral coefficients (MFCC) and linear predictive coding (LPC). Thus, making the PaMZ-HMM suitable for real-time detection.
被动声学监测(PAM)通常用于提取鲸目动物产生的声学信号。然而,PAM过程中的大数据量可以使用诸如隐藏马尔可夫模型(HMM)之类的自动化技术进行更好的分析。在本文中,HMM由于其鲁棒性和低时间复杂度而被用作检测和分类技术。尽管如此,某些参数,例如要从信号中提取的特征的选择、帧持续时间和状态的数量,会影响模型的性能。结果表明,随着状态数的增加,HMM表现出最好的性能。然而,增加状态的数量会增加模型的计算复杂性。近海的布氏鲸发出具有明显信号特征的短脉冲叫声,这些信号在时域中是可观察到的。因此,利用时域特征向量来降低HMM的复杂度。仿真结果还表明,与基于HMM技术的其他特征向量相比,作为时域特征向量的平均功率提供了最佳性能,用于检测近海Bryde's鲸的短脉冲叫声。更重要的是,提取的特征,例如平均功率、平均值和过零率,被组合以形成单个三维向量(PaMZ)。与现有的特征提取技术(如梅尔尺度频率倒谱系数(MFCC)和线性预测编码(LPC))相比,PaMZ HMM显示出改进的性能和降低的复杂性。因此,使得PaMZ HMM适合于实时检测。
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引用次数: 4
期刊
SAIEE Africa Research Journal
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