A biomimetic approach to inverse kinematics for a redundant robot arm

Redundant robots have received increased attention during the last decades, since they provide solutions to problems investigated for years in the robotic community, e.g. task-space tracking, obstacle avoidance etc. However, robot redundancy may arise problems of kinematic control, since robot joint motion is not uniquely determined. In this paper, a biomimetic approach is proposed for solving the problem of redundancy resolution. First, the kinematics of the human upper limb while performing random arm motion are investigated and modeled. The dependencies among the human joint angles are described using a Bayesian network. Then, an objective function, built using this model, is used in a closed-loop inverse kinematic algorithm for a redundant robot arm. Using this algorithm, the robot arm end-effector can be positioned in the three dimensional (3D) space using human-like joint configurations. Through real experiments using an anthropomorphic robot arm, it is proved that the proposed algorithm is computationally fast, while it results to human-like configurations compared to previously proposed inverse kinematics algorithms. The latter makes the proposed algorithm a strong candidate for applications where anthropomorphism is required, e.g. in humanoids or generally in cases where robotic arms interact with humans.     

MITIS: a WWW-based medical system for managing and processing gynecological-obstetrical-radiological data

In this paper a World Wide Web (WWW)-based medical system, called MITIS, is designed and developed for the management and processing of obstetrical, gynecological and radiological medical data. The system records all the necessary medical information in terms of patient data, examinations, and operations and provides the user-expert with advanced image processing tools for the manipulation, processing and storage of ultrasound and mammographic images. The system can be installed in a hospital's Local Area Network (LAN) where it can access picture archival and communication systems (PACS) servers (if available), or any other server within the radiology department, for image archiving and retrieval, based on the digital imaging and communication in medicine (DICOM) 3.0 protocol, over TCP/IP and also it is accessible to external physicians via the hospital's Internet connection. MITIS is composed as a set of independent WWW modules (ISAPI server extension dlls) and a Win32 application (COM+ server) for mammography image processing and evaluation.     

Pin-on-disc testing of PE-CVD diamond-like carbon coatings on tool steel substrates

The present study deals with the tribological behaviour and the wear mechanisms of 2-μm thick diamond-like carbon coatings. The examined coatings were deposited by plasma-enhanced chemical vapour deposition (PE-CVD) on three tool steel substrates, of different hardnesses. Tribological studies against alumina were performed using a pin-on-disc apparatus under various normal loads (2–20 N) and sliding speeds (0.1–0.3 m s⁻¹), while the relative humidity of the environment was kept constant, equal to 25%. The influence of the testing parameters (normal load and sliding speed) and the mechanical properties of the substrate on the wear lifetime of the coatings was determined and the involving wear mechanisms were identified. It was found that both the sliding conditions and the hardness of the substrate affect strongly the wear rate and the wear lifetime, but have no significant influence on the value of the friction coefficient, which was found to be lower than 0.15 for all the testing parameters.     

Numerical Investigation of a 160-Gb/s Reconfigurable Photonic Logic Gate Based on Cross-Phase Modulation in Fibers

A simple reconfigurable all-optical logic gate based on cross-phase modulation in highly nonlinear fibers is numerically demonstrated. Fine performance at 160 Gb/s is obtained for five logic functions (xor, or, nand, nor and not). The implementation simplicity and the high-bit-rate operation make the proposed device suitable for ultrafast applications in the emerging all-optical networks     

Indoor environments propagation simulation using a hybrid MoM and UTD electromagnetic method

Radio channel observation and characterization is indispensable in mobile communications systems development. Efficient propagation prediction is crucial for rapid and cost-effective systems deployment. On-site measurements, statistical models, propagation prediction and deterministic modeling are widely used for the qualification of radio channels. In this paper, a simulation tool for deterministic channel modeling in indoor environments is evolved. A hybrid combination of the Method-Of-Moments (MoM) and the Uniform Theory of Diffraction (Utd) is used. Statistical characteristics of a simple office room are calculated and the results are in excellent agreement with corresponding results of relative research on the field.     

Simulation of piston ring tribology with surface texturing for internal combustion engines

Design of piston rings is a very crucial subject in the field of internal combustion engines. In the present paper, a numerical model is created using the Navier–Stokes equations. Fluid–structure interaction analysis is performed in order to calculate the structural integrity of the ring for several engine operational conditions and texturing patterns. This paper illustrates the hydrodynamic friction force under various surface artificial texturing in terms of spherical and rectangular microdimples. Piston ring stress analysis is also investigated due to gas leakage. Results show a substantial reduction of the friction using rectangular texturing and less reduction using spherical texturing. The rectangular microdimple parameters were considered to obtain a better friction reduction with the following configurations: H_d = 4 µm, ρ_τ = 0.61, λ = 20 and s = 0.004. Each rectangular texture cell is defined by the dimple depth, H_d; the texture density, ρ_τ; the dimple aspect ratio, λ; and the relative dimple depth, s. Copyright © 2014 John Wiley & Sons, Ltd.