Integrated Mobility and QoS Control in Cellular Wireless ATM Networks

This paper presents a traversed pathtracking-based technique for integrated mobility andquality-of-service (QoS) management of connections incellular wireless ATM networks. Simulation andanalytical results for probabilities of connectionBlocking, Dropping, and Unsuccessful Connections aredetermined. A distributed operating system-basedarchitecture for implementation of integrated mobilityand QoS control is then proposed. The objective is totreat mobility as a network impairment triggeredactivity which is to be handled via QoS management.Depending on the speed of the mobile unit and thecategory of service being used, the QoS of a connectionmay or may not vary continuously during a session. Theresults presented here consider coexistence of constantbit-rate and nonreal-time variable bitrate ATM connections over a single session.     

Design of an Under-Actuated Exoskeleton System for Walking Assist While Load Carrying

This study proposes an under-actuated wearable exoskeleton system to carry a heavy load. To synchronize that system with a user, a feasible modular-type wearable system and its corresponding sensor systems are proposed. The design process of the modular-type exoskeleton for lower extremities is presented based on the considered requirements. To operate the system with the user, human walking analysis and intention signal acquisition methods for actuating the proposed system are developed. In particular, a sensing data estimation strategy is applied to synchronize the exoskeleton system with a user correctly. Finally, several experiments were performed to evaluate the performance of the proposed exoskeleton system by measuring the electromyography signal of the wearer's muscles while walking on level ground and climbing up stairs with 20- to 40-kg loads, respectively.     

Towards grasping in unstructured environments: grasper compliance and configuration optimization

This paper examines the role of grasper compliance and kinematic configuration in environments where object size and location may not be well known. A grasper consisting of a pair of two-link planar fingers with compliant revolute joints was simulated as it passively deflected during contact with a target object. The kinematic configuration and joint stiffness values of the grasper were varied in order to maximize successful grasp range and minimize contact forces for a wide range of target object size. Joint rest angles around 25–45 degrees produced near-optimal results if the stiffness of the base joint was much smaller than the intermediate joint, as confirmed experimentally.     

Design and Realization of a Non-Circular Cable Spool to Synthesize a Nonlinear Rotational Spring

In this paper we present a cable mechanism that realizes a nonlinear rotational spring from a linear translational spring. The spring is pulled by a cable wound around a non-circular spool, which is rigidly attached to the joint. The non-circular shape of the spool induces a nonlinear relationship between its angular position and the torque created by the tension of the cable. Depending on the shape of the spool, various torque–angle relationships can be realized. We show that for a given nonlinear torque–angle relationship, there is an explicit expression (closed-form solution) of the shape of the spool that synthesizes this function. First, we present the geometry of the problem. Then, we derive the methodology to calculate the shape of the spool to synthesize a prescribed torque–angle relationship. Finally, we verify the design methodology by experiments with three different spools realizing a constant force spring, an exponential softening spring and a cubic polynomial spring. We discuss the possible sources of errors between the theoretical and experimental results.     

Mechanism Design and Gait Experiment of an Amphibian Robotic Turtle

In this paper we describe the design of a new bio-inspired amphibian robot with high environmental adaptability. The robot, called MiniTurtle-I, can transform terrestrial and aquatic locomotion configurations through a new variable topology mechanism (Leg-Flipper). Based on the modular design philosophy, four rotatory joint modules (Joints I–IV) constitute a Leg-Flipper module. Variable topology structure transformation of Leg-Flipper by actuation redundancy enables the robot to achieve a variety of locomotion. Our motivation is to provide another solution to achieve amphibious movement both easily and efficiently. A prototype of MiniTurtle-I is built to exam the configuration transformations. Terrestrial, aquatic and semiaquatic gait experiments are performed to verify the locomotion functions of the MiniTurtle-I.     

Interaction between magnesia and graphite bricks in furnace producing vanadium nitride

Abstract

A cavity between magnesia bricks and graphite slabs was found in a commercial furnace produced vanadium nitride after a 13 months campaign. The magnesia, zirconia–corundum–mullite and hollow sphere Al₂O₃ bricks taken from the dismantled furnace were investigated by chemical analysis, XRD and SEM. It was found that the compositions of magnesia bricks, which contact with graphite slabs, were almost not changed but the thickness of remaining bricks was far lower than that of the original ones. Spinel was detected in used zirconia–corundum–mullite bricks and hollow sphere Al₂O₃ bricks, which were above MgO bricks. A mechanism of cavity formation was proposed. This result may be a new evidence of reaction mechanism between magnesia and graphite via gas phase.     

Development of a single-master multi-slave tele-micromanipulation system

This paper proposes the development of a human–robot cooperative tele-micromanipulation system through a network. We have developed a novel single-master (PHANToM haptic device) multi-slave (6-d.o.f. parallel manipulator) scaled tele-micromanipulation system which enables human operators to perform meso or small-size object manipulation such as assembly or manufacturing with sufficient telepresence. It is expected to improve the human's operability and the overall dexterity of conventional tele-micromanipulation systems. To overcome the problems of the multiple parallel mechanism manipulator, virtual kinematic mapping is considered, based on the manipulability analysis of the workspace. The pick-and-place experiment results prove the validity of the developed single-master multi-slave system.     

Air-Flow-Based Single-Cell Dispensing System

We discuss a design and fabrication approach to increase the success rate of single-cell dispensing. Two pairs of capacitance sensors are placed in a biochip to detect the flow velocity of cells and air pressure is applied to eject cells by synchronizing the timing. A comprehensive design theory, which takes into account the back-pressure caused by the air pressure, the response time of the system, the sensor properties and the delay of the dispensing from the air pressure, is developed in order to minimize the disturbance of the system and maximize the throughput of the ejection system. Then, the system theoretically has a capability to eject 3 cells/s and the maximum flow velocity is 10 mm/s. The novelty of the system is that the biochip is disposable, which is unlike the conventional mechanical inkjet system; because the biochip is low cost and disposable this prevents contamination and means the drive system is reusable. Finally, we succeeded in automatic dispensing of a single polystyrene bead (100 μm) from a biochip to a culture well atmosphere using the developed cell ejection system with a success rate of 50%. Furthermore, we also succeeded in single swine oocyte dispensing by using the developed system.     

Thermal and hygroscopic reliability of flip-chip packages with an anisotropic conductive film

Thermal and hygroscopic reliability of anisotropic conductive film (ACF) joints in relation to flip-chip bonding force was evaluated by thermal shock and constant temperature/humidity testing. The failure mode by thermal shock testing varied with increasing bonding force, i.e., (1) formation of a conduction gap between conductive particles and Au bump or Ni/Au plated Cu pad at low bonding force and (2) delamination of adhesive matrix from the plated Cu pad on the flexible substrate at high bonding force. The delamination initiated as a crack under a conductive particle and propagated sideward resulting in a complete delamination of the ACF from the Cu pad. However, delamination was observed between the ACF and Au bump on the chip side after the constant temperature/humidity testing for 500 h. A theoretical calculation was also conducted to predict the connection resistance of the ACF joint before and after reliability tests. The calculation showed the importance of the bonding gap between the electrodes.     

Investigation on compressibility of Al–SiC composite powders

Abstract

The consolidation behaviour of particulate reinforced metal matrix composite powders during cold uniaxial compaction in a rigid die was studied. Al–SiC powder mixtures with varying SiC particle size, ranging from nanoscale (50 nm) to microscale (40 µm), at different volume fractions up to 30% were used. Based on the experimental results, the effect of the reinforcement particles on the densification mechanisms, i.e. particle rearrangement and plastic deformation, was studied using modified Cooper–Eaton equation. It was found that by increasing the reinforcement volume fraction or decreasing its size, the contribution of particle rearrangement on the densification increases while the plastic deformation becomes restricted. In fact, when percolation network of the ultrafine reinforcement particles is formed, the rearrangement could be the dominant mechanism of consolidation. It was also shown that at tap condition and at the early stage of compaction where the particle rearrangement is dominant, the highest density is achieved when the reinforcement particle size is properly lower than the matrix (0˙3<the size ratio<0˙5) and the fraction of hard particles is relatively low (<10%). At high compaction pressures, the reinforcement particles significantly influence the yield pressure of composite powders, thereby retarding the densification.