Abstract As virtual reality (VR) simulators become increasingly central to technical training, realistic haptic feedback is often assumed to enhance user experience, skill acquisition, and transfer to real-world tasks. This study investigates the impact of haptic feedback on basic technical motor skill training in VR, focusing on early-stage skills involving bimanual coordination, fine motor control, and precise tool-mediated object placement under visual and temporal constraints, with limited force modulation requirements. An immersive simulator implementing a bimanual “Ring Transfer” task was developed, requiring participants to precisely grasp and transfer small objects using two tools under visual guidance and timing constraints, with minimal force modulation. A closely matched physical setup replicating workspace dimensions, tool geometry, and interaction mechanics was used to assess skill transfer. Twenty-four novice participants were assigned to three groups: haptic (HC), no-haptic (NC), and control (CC), consistent with an a priori power analysis. The HC and NC groups completed nine training sessions over two weeks, followed by post-test and delayed retention evaluations conducted one week later. Performance was measured using task completion time and error rate, and user experience was assessed using the System Usability Scale (SUS) and a validated Presence Questionnaire. Results show that the NC group initially outperformed the HC group, likely due to increased cognitive and sensorimotor demands associated with adapting to force feedback. However, the latter demonstrated greater performance improvement over time. Both groups reported high usability, while the HC group reported significantly higher scores on the haptics dimension of the Presence Questionnaire. In the physical post-test, both trained groups significantly outperformed the control group, confirming effective transfer from VR to real-world performance. However, no significant difference was found between the HC and NC groups, indicating that the increased perceived realism associated with haptic feedback did not translate into measurable performance gains for this task. These findings highlight a task-dependent role of haptic feedback. In this study, basic tasks are characterized by a predominant reliance on visual guidance and spatial precision, with limited requirements for force control or tactile discrimination. For such tasks, visual information alone may be sufficient to support skill transfer. This suggests that the benefits of haptics in VR training depend on task demands, particularly the extent to which force control and tactile cues are required, whereas tasks involving significant force modulation or interaction with deformable objects may benefit more from haptic feedback.

With the increasing use of immersive simulators in surgical training, there is an emerging emphasis on providing realistic haptic feedback. Although haptic feedback is recognized as necessary for surgical skill acquisition, its role in transferring those skills to real-life situations still needs to be explored. Our study aims to investigate the impact of haptic feedback on basic microsurgery skill acquisition, transfer, and retention, as well as on the user experience during VR training. An immersive simulator was developed to practice a microgrid task under magnification with and without haptic feedback. A similar physical setup with a binocular microscope was also designed to measure skills transfer to the real world. Thirty-three volunteers ($N=33$) were randomly divided into three participant groups: the haptic feedback group (HG), the no-haptic feedback group (NG), and the control group (CG). All participants performed the task on the physical setup during the pre-post-retention tests. After the pre-test, the first two groups performed six training trials on the immersive simulator, with the HG group receiving haptic feedback while performing the task. The control group did not receive any training. The results show that the HG and NG groups significantly improved their learning curve during training, with no significant differences between them. On the Other hand, the haptic feedback led to significantly higher usability and possibility of examination scores than those without haptic feedback. Finally, all the groups improved their time performance on the physical simulator. In addition, the haptic group participants showed a more significant gain in performance in terms of accuracy and error rates. These findings confirm the effectiveness of immersive environments combined with haptic feedback as a valuable training tool, facilitating the transfer of technical skills to realworld applications. Moreover, the results indicate that haptic feedback can also improve the user experience in immersive surgical simulators.

Retinal vessel segmentation constitutes an essential part of computer‐assisted tools for the diagnosis of ocular diseases. In this study, the authors propose an unsupervised retinal blood vessels segmentation approach based on the elite‐guided multi‐objective artificial bee colony (EMOABC) algorithm. The proposed method exploits several criteria simultaneously to improve the accuracy of the segmentation results. An energy curve function is used to calculate the values of the thresholding criteria, in order to reduce the noise response from lesions and select the optimal thresholds that separate the blood vessels from the background. In order to achieve computational speed up, a stopping criterion method is used to adjust the parameters of the EMOABC algorithm. The proposed method is computationally simple and faster than most of the available unsupervised algorithms, demonstrating fast convergence to the final segmentation. Additionally, the proposed vessel segmentation method outperforms the metaheuristics vessels segmentation algorithms reported in the literature. The achieved mean discrepancy metrics for the proposed approach are 94.5% accuracy, 97.4% specificity and 73.9% sensitivity for DRIVE database, and 94% accuracy, 96.2% specificity and 73.7% sensitivity for STARE database.

In this paper, we present a GPU accelerated volume carving technique, that aims to estimate and render on the fly all visible parts of a visual hull from a novel viewpoint. We have carefully adapted our algorithm implementation to the recent GPU-programming tools: CUDA (NVIDIA Compute Unified Device Architecture) and Modern OpenGL GLSL. We were able to carve out the desired part of the 3D volume, then estimating the surface colours. Our obtained results show an improvement in term of image quality and also the rendering time.

In Open MAS (Open Multi Agent Systems), agents can freely join and leave systems at any time. The inherent specificities of such systems like dynamicity, non-determinism and emergency make their target states difficult to achieve. Agents, in Open MAS, are often heterogeneous, self-interested with conflicting individual goals and limited trust. Consequently, newly entered (external) agents are often considered as a potential disturbance of systems. In this paper, we present a novel preventive control approach based on Aspect-Oriented Programming (AOP) paradigm for mastering Open MAS’ behaviour. The proposed control process is mainly accomplished in two steps: (1) Observing agents movements by intercepting all external requests of agents wanting accessing to the system. A request analysis process will be held in terms of compliance capabilities presented by this agent, and (2) Deciding, based on AspectJ constructors, either to allow agents if the capabilities they have enable a possible progress in actual system state to the target state, or prevent it otherwise. The proposed approach is illustrated using a MaDKit-based application.

This paper presents a contribution in matter of robustness of a previous method of 3D objects watermarking [10] based on wavelet decomposition on semi-regular triangular meshes. This decomposition gives rise to a multiresolution mesh where the watermark could be embedded at each level of resolution, in this case we talk about a hierarchical watermarking. In practice the robustness of the previous method against geometrical attacks was high only in the low resolution which makes it far from being a hierarchical method. Our analysis made on the fragility of that method allowed us to reveal the cause which was not primarily the bad bits quantization of the watermark, but rather the alteration of the sequencing of the embedded bits (synchronization). Our contribution is to replace the previous geometrical mechanism with a new topological synchronization mechanism, which has resulted a real hierarchical and robust watermarking.