Hierarchical Graph Neural Networks for Proprioceptive 6D Pose Estimation of In-hand Objects

Robotic manipulation, in particular in-hand object manipulation, often requires an accurate estimate of the object's 6D pose. To improve the accuracy of the estimated pose, state-of-the-art approaches in 6D object pose estimation use observational data from one or more modalities, e.g., RGB images, depth, and tactile readings. However, existing approaches make limited use of the underlying geometric structure of the object captured by these modalities, thereby, increasing their reliance on visual features. This results in poor performance when presented with objects that lack such visual features or when visual features are simply occluded. Furthermore, current approaches do not take advantage of the proprioceptive information embedded in the position of the fingers. To address these limitations, in this paper: (1) we introduce a hierarchical graph neural network architecture for combining multimodal (vision and touch) data that allows for a geometrically informed 6D object pose estimation, (2) we introduce a hierarchical message passing operation that flows the information within and across modalities to learn a graph-based object representation, and (3) we introduce a method that accounts for the proprioceptive information for in-hand object representation. We evaluate our model on a diverse subset of objects from the YCB Object and Model Set, and show that our method substantially outperforms existing state-of-the-art work in accuracy and robustness to occlusion. We also deploy our proposed framework on a real robot and qualitatively demonstrate successful transfer to real settings

Nonlinear System Identification of Laboratory Heat Exchanger Using Artificial Neural Network Model

This paper addresses the nonlinear identification of liquid saturated steam heat exchanger (LSSHE) using artificial neural network model. Heat exchanger is a highly nonlinear and non-minimum phase process and often its working conditions are variable. Experimental data obtained from fluid outlet temperature measurement in laboratory environment is used as the output variable and the rate of change of fluid flow into the system as input too. The results of identification using neural network and conventional nonlinear models are compared together. The simulation results show that neural network model is more accurate and faster in comparison with conventional nonlinear models for a time series data because of the independence of the model assignment.DOI:http://dx.doi.org/10.11591/ijece.v3i1.195

Time-domain Classification of the Brain Reward System: Analysis of Natural- and Drug-Reward Driven Local Field Potential Signals in Hippocampus and Nucleus Accumbens

Addiction is a major public health concern characterized by compulsive reward-seeking behavior. The excitatory glutamatergic signals from the hippocampus (HIP) to the Nucleus accumbens (NAc) mediate learned behavior in addiction. Limited comparative studies have investigated the neural pathways activated by natural and unnatural reward sources. This study has evaluated neural activities in HIP and NAc associated with food (natural) and morphine (drug) reward sources using local field potential (LFP). We developed novel approaches to classify LFP signals into the source of reward and recorded regions by considering the time-domain feature of these signals. Proposed methods included a validation step of the LFP signals using autocorrelation, Lyapunov exponent and Hurst exponent to assess the meaningful stability of these signals (lack of chaos). By utilizing the probability density function (PDF) of LFP signals and applying Kullback-Leibler divergence (KLD), data were classified to the source of the reward. Also, HIP and NAc regions were visually separated and classified using the symmetrized dot pattern technique, which can be applied in real-time to ensure the deep brain region of interest is being targeted accurately during LFP recording. We believe our method provides a computationally light and fast, real-time signal analysis approach with real-world implementation.Comment: 12 pages, 7 figures first two authors contributed equally to this wor

Statistical Studies of Fading in Underwater Wireless Optical Channels in the Presence of Air Bubble, Temperature, and Salinity Random Variations (Long Version)

Optical signal propagation through underwater channels is affected by three main degrading phenomena, namely absorption, scattering, and fading. In this paper, we experimentally study the statistical distribution of intensity fluctuations in underwater wireless optical channels with random temperature and salinity variations as well as the presence of air bubbles. In particular, we define different scenarios to produce random fluctuations on the water refractive index across the propagation path, and then examine the accuracy of various statistical distributions in terms of their goodness of fit to the experimental data. We also obtain the channel coherence time to address the average period of fading temporal variations. The scenarios under consideration cover a wide range of scintillation index from weak to strong turbulence. Moreover, the effects of beam-collimator at the transmitter side and aperture averaging lens at the receiver side are experimentally investigated. We show that the use of a transmitter beam-collimator and/or a receiver aperture averaging lens suits single-lobe distributions such that the generalized Gamma and exponential Weibull distributions can excellently match the histograms of the acquired data. Our experimental results further reveal that the channel coherence time is on the order of $10^{-3}$ seconds and larger which implies to the slow fading turbulent channels

Residual refractive errors in pseudophakic eyes and related factors: a population-based study

AIM: To determine residual refractive error after cataract surgery in pseudophakic eyes and its relationship with age, sex, and axial length (AL). METHODS: In this population-based cross-sectional study, the sampling was performed on individuals aged 60y and above in Tehran, Iran using a multi-stage stratified random cluster sampling method. Pseudophakic eyes with a best-corrected visual acuity of 20/32 or better were analyzed and their refractive results were reported. RESULTS: The mean spherical equivalent (SE) refraction was -0.34±0.97 diopters (D) and the mean absolute SE was 0.72±0.74 D with a median of 0.5 D. Moreover, 32.68% (n=546, 95%CI: 30.27%-35.08%), 53.67% (n=900, 95%CI: 51.23%-56.1%), 68.99% (n=1157, 95%CI: 66.96%-71.02%), and 79.73% (n=1337, 95%CI: 77.69%-81.76%) of the eyes had a residual SE within ±0.25, ±0.50, ±0.75, and ±1.00 D of emmetropia, respectively. According to the multiple logistic regression model, increasing age was associated with a statistically significant decrease in predictability for all cut points. Moreover, the predictability based on all cut points was significantly lower in individuals with an AL longer than 24.5 mm than in those with an AL between 22 to 24.5 mm. CONCLUSION: Based on the results, the accuracy of intraocular lens (IOL) power calculation is lower for those who underwent cataract surgery during the last 5y in Tehran, Iran. Among the most important influential factors, the choice of IOL or it's power disproportionate to eye conditions and age can be mentioned

Investigating Personal Knowledge Management and Its Mediating Role on the Impact of Psychological Characteristics on Organizational Competencies in Information and Knowledge Services

Introduction: Today, the secret of the success of any organization is the knowledge management. Because knowledge is such, it should only be done by oneself individually. So, this causes raising different psychological concepts in knowledge management. Given the undeniable role of individuals in today's business excellence, personal knowledge management topics vs. organizational knowledge management topics are discussed. The aim of this study was to investigate the moderating role of personal knowledge management on the impact of psychological characteristics on organizational competencies in information and knowledge services. Methodology: This is an applied study with a mixed method. The sample in qualitative section consisted of ones with research experiences in the field of personal knowledge management, and in the quantitative section, the staff of central libraries of Tehran’s state universities. For this purpose, a researcher-made questionnaire with the seven dimensions of retrieving, evaluating, organizing, collaborating, analyzing, providing, and securing information was used for studying personal knowledge management, and the Neo questionnaire was used for the study of psychological characteristics, and a researcher-made questionnaire was used with the five dimensions of external information awareness, internal knowledge dissemination, effective decision architecture, organizational focus, and continue innovation for measuring organizational competencies. The reliability of the questionnaire has been evaluated by Cronbach’s Alpha, which was equal to .728. Data was analyzed by the descriptive and inferential statistics methods. Findings: The results showed that the psychological characteristics have a direct effect on personal knowledge management and personal knowledge management has a direct effect on organizational competencies. The impact of psychological characteristics on organizational competencies was not confirmed, and the role of personal knowledge management was detected as a mediator. Conclusion: According to the results, in evaluating the personal knowledge of library staff, special attention should be paid on their personalities. To achieve the desired organizational competencies, the skills of library staff should be strengthen for their personal knowledge management

Investigating Personal Knowledge Management and Its Mediating Role on the Impact of Psychological Characteristics on Organizational Competencies in Information and Knowledge Services

Introduction: Today, the secret of the success of any organization is the knowledge management. Because knowledge is such, it should only be done by oneself individually. So, this causes raising different psychological concepts in knowledge management. Given the undeniable role of individuals in today's business excellence, personal knowledge management topics vs. organizational knowledge management topics are discussed. The aim of this study was to investigate the moderating role of personal knowledge management on the impact of psychological characteristics on organizational competencies in information and knowledge services. Methodology: This is an applied study with a mixed method. The sample in qualitative section consisted of ones with research experiences in the field of personal knowledge management, and in the quantitative section, the staff of central libraries of Tehran’s state universities. For this purpose, a researcher-made questionnaire with the seven dimensions of retrieving, evaluating, organizing, collaborating, analyzing, providing, and securing information was used for studying personal knowledge management, and the Neo questionnaire was used for the study of psychological characteristics, and a researcher-made questionnaire was used with the five dimensions of external information awareness, internal knowledge dissemination, effective decision architecture, organizational focus, and continue innovation for measuring organizational competencies. The reliability of the questionnaire has been evaluated by Cronbach’s Alpha, which was equal to .728. Data was analyzed by the descriptive and inferential statistics methods. Findings: The results showed that the psychological characteristics have a direct effect on personal knowledge management and personal knowledge management has a direct effect on organizational competencies. The impact of psychological characteristics on organizational competencies was not confirmed, and the role of personal knowledge management was detected as a mediator. Conclusion: According to the results, in evaluating the personal knowledge of library staff, special attention should be paid on their personalities. To achieve the desired organizational competencies, the skills of library staff should be strengthen for their personal knowledge management

Analysis of photovoltaic technology development based on technology life cycle approach

Increasing energy demand has created the challenge of supplying safe, economical, and durable energy with minimal impact on the environment. Therefore, governments have developed and executed several strategies such as increasing efficiency in energy systems in addition to replacing existing sources with renewable energies. One of the most important renewable energy sources that have a competitive advantage compared with other resources is solar energy and its related technologies. However, development of this technology, its related products, and their competitiveness in the market has created a plethora of challenges. In this study, the focus is on the analysis of photovoltaic technology development in the context of different technology generations. The S-shape curve of each generation and sub-technologies of photovoltaic is designed and analyzed. Results show that the first generation of photovoltaic technology is in growth and early maturity stage. The second generation is also in growth stage, but the third generation is mainly in the introduction stage.fi=vertaisarvioitu|en=peerReviewed