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We present a three-dimensional microwave antenna design, which can provide strong and spatially homogeneous GHz microwaves for efficient driving of nitrogen-vacancy (NV) ensembles in a diamond. From numerical simulation, we find the field strength to be as large as ~ 21 G at 2.87 GHz equivalent to an ~ 60 MHz Rabi frequency. In addition, the field remains uniform over an ~ mm3 volume of the diamond. We determine the antenna parameters and configurations based on quantitative analyses of the simulation results in terms of the loop radius, the number of coil, the dielectric materials and the coil configurations of the solenoid and Helmholtz coil. The antenna design studied in this research can be used in various sensing applications based on the NV ensemble, where a strong and uniform microwave drive is necessary.

The development of magnetic sensors simultaneously satisfying high magnetic sensitivity and high spatial resolution becomes more important in a wide range of fields including solid-state physics and life science. The nitrogen-vacancy (NV) center in diamond is a promising candidate to realize nanometer-scale magnetometry due to its excellent spin coherence properties, magnetic field sensitivity, atomic-scale size and versatile operation condition. Recent experiments successfully demonstrate the use of NV center in various sensing and imaging applications. In this chapter, we review the basic sensing mechanisms of the NV center and introduce imaging applications based on scanning magnetometry and wide field-of-view optics.

In this study we present our recent achievements in industrial applications of terahertz technology: Cost-effective high-speed reflective imaging nondestructive testing (NDT) system, real-time thickness monitoring system of slurry film, and other recent works.

Sensing temperature with high precision and high spatial resolution is challenging and requires novel temperature measurement techniques. Recently, an atomic-scale thermal sensor based on a defect center in diamond, i.e., a nitrogen-vacancy (NV) center, has been developed, and successfully demonstrated temperature sensing at the mK level and a few tens of nanometers. Here we discuss a temperature sensing mechanism based on the NV center in both experimental and theoretical aspects. At room temperature, we show temperature sensing over a wide-range of temperatures ∼90 K with a precision of 0.2 K. We also map temperature gradients in a bridge-like device a few hundreds of micrometers long. In addition, we theoretically compare three sensing protocols and analyze temperature sensitivity to find optimal measurement time and NV concentration for the ensemble measurement.

In the field of strain-based hybrid mechanical systems, understanding the local strain profile and realizing strong strain coupling is crucial. Here a theoretical investigation is conducted on hybrid devices consisting of diamond membranes with a high Q-factor and embedded nitrogen-vacancy defect centers. Simulation based on a three-dimensional finite element method reveals microscopic strain distribution in the membrane’s basis as well as in the defect’s basis. For strong strain coupling, we design diamond phononic crystal devices with a honeycomb lattice, enabling localized strain in a small mode volume and an enhanced Q-factor. The hybrid devices studied in this paper are promising candidates for various quantum applications, including strain-mediated long range spin-spin interaction, multi-mode optomechanics, and topological operations with exceptional points.

This study presents a probabilistic response analysis of seismically isolated electrical transformers with emphasis on comparing the performance of equipment that are non-isolated to equipment that are isolated only in the horizontal direction or are isolated by a three-dimensional isolation system. The performance is assessed by calculating the probability of failure as function of the seismic intensity with due consideration of: (a) horizontal and vertical ground seismic motions, (b) displacement capacity of the seismic isolation system, (c) limit states of electrical bushings, (d) details of construction of the isolation system, (e) weight of the isolated transformer, and (f) bushing geometry and configuration. Calculations of the probability of failure within the lifetime of isolated and non-isolated transformers at selected locations are also performed. The results of this study demonstrate that seismic isolation systems can improve the seismic performance for a wide range of parameters and that systems which isolate in both the horizontal and vertical directions can be further effective. The seismic assessment methodology presented can be used for: (a) deciding on the need to use seismic isolation and selecting the properties of the isolation system for transformers depending on the design limits, location, and configuration of transformer and (b) calculating the mean annual frequency of functional failure and the corresponding probability of failure over the lifetime of the equipment. The results may also be used to assess the seismic performance of electric transmission networks under scenarios of component failures.

In this study, the calibrations of the lower-limb kinematics based on the five wearable IMU sensors were performed to reduce the inherent kinematic errors due to the both incorrect measurements of the kinematic parameters and the uncertainties of the geometric modeling of the lower-limb joints. Unlike the actual body structure, the ankle and knee joint of the lower-limb part are generally modeled as pure revolute joints of two or three degrees of freedom with some assumptions. However, it is obvious that these mismatches in the simplified geometrical modeling of the joint in the lower-limb kinematics lead to uncertainties in the model-based 3D motion tracking of human body such as walking velocity estimation, gait analysis, etc. As main research contributions, we intended to examine exactly which error factors are responsible for the kinematic uncertainties that arises from the 3D motion tracking based on the lower-limb kinematics and wearable IMU sensors. The lower-limb kinematics model in this research assumes that the ankle, knee, and hip joints are all three degrees of freedom, and that the three principle axes at each joint may not intersect at a common point. That is, the kinematic uncertainties included in the joint model will be confirmed by performing a kinematic calibration taking into account the orientation of joint axes and joint offsets as kinematic error parameters as well as the case of only calibrating the link lengths. This study also uses a new calibration plate with seven sole-shaped jigs and five wearable IMU sensors to measure the actual pose of the right foot, which is the distal end of the lower-limb kinematics with respect to the left foot. In order to secure an in-depth insight into the wearable IMU sensor based calibrations of the lower-limb kinematics, the seven sole-shaped jigs were designed to independently allow the right foot on those jigs to have predefined 3-dof poses. Finally, an iterative least square method is adopted to minimize the error between the nominal kinematic model-based pose and the actual poses of the right foot with respect to the left foot on the calibration plate. In an experiment with one subject, the reduction rate of the position error depends on the measurement of the initial kinematic parameters, but the RMS position error of the right foot relative to the left foot was improved by 336.1% from 36.5 mm to 11.3 mm.

In this research, a new control law for the trajectory correction maneuver (TCM) is proposed for a spacecraft assumed to be actuated by a low thruster such as an electric propulsion system. During the cruise phase of an interplanetary mission, trajectory errors accumulate continuously owing to unpredictable perturbation forces. In previous research, TCM algorithms were developed under the assumption that the thruster is impulsive. Since the required delta velocity for the TCM is relatively small and there are numerous advancements currently underway in electric propulsion systems, this paper proposes a new control law for the TCM using a low thruster. In the proposed control law, the B-plane targeting method widely used in interplanetary missions is employed as a target parameter and the Lyapunov feedback control theory is also used. The efficiency of the new control law is demonstrated through numerical simulations.

We demonstrate two-dimensional mapping of current flow in graphene devices by using a single-spin scanning magnetometer based on a nitrogen-vacancy defect center in diamond. We first image the stray magnetic field generated by the current and then reconstruct the current density map from the field data. We focus on the visualization of current flow around a small sized current source of ∼500 nm diameter, which works as an effective point contact. In this paper, we study two types of point-contacted graphene devices and find that the overall current profiles agree with the expected behavior of electron flow in the diffusive transport regime. This work could offer a route to explore interesting carrier dynamics of graphene including ballistic and hydrodynamic transport regimes.

A pinpoint soft landing with a low touchdown velocity is critical for a lunar lander in the terminal landing phase, particularly with respect to scientific exploration missions. However, the main descent thruster of the lander is usually equipped on one side along the body axis, whereas reaction thrusters for attitude control are fixed in three axes. This causes the translational dynamics and the rotational dynamics of the lunar lander to be mutually coupled. In this study, a new force–torque sequential control law is introduced to resolve the coupling effect. To further improve the coupled motion, a virtual landing trajectory augmented control law is designed. The virtual trajectory is represented as a virtual quaternion and is augmented as a command to the lander’s position update using the dual quaternion. A combined augmented landing control algorithm is newly proposed to incorporate the virtual trajectory commands into the force–torque sequential control law. Numerical simulation results with some ca...

This paper describes the behavior of the quintuple friction pendulum isolator, a spherical sliding isolator with six sliding surfaces, five effective pendula, and nine regimes of operation that allow for complex multi-stage adaptive behavior depending on the amplitude of displacement. An analytical model is presented that is capable of tracing the behavior of the isolator in two general configurations of geometric and frictional properties. This analytical model is useful for verifying computational models and in performing simplified calculations for analysis and design. A computational model that can be implemented in the program SAP2000 is also presented and verified by comparison to the analytical model. A model quintuple friction pendulum isolator has been tested and the results have been used to validate the analytical and computational models.

It is well known that, to locate humans in GPS-denied environments, a lower limb kinematic solution based on Inertial Measurement Unit (IMU), force plate, and pressure insoles is essential. The force plate and pressure insole are used to detect foot-ground contacts. However, the use of multiple sensors is not desirable in most cases. This paper documents the development of an IMU-based FGCD (foot-ground contact detection) algorithm considering the variations of both walking terrain and speed. All IMU outputs showing significant changes on the moments of foot-ground contact phases are fully identified through experiments in five walking terrains. For the experiment on each walking terrain, variations of walking speeds are also examined to confirm the correlations between walking speed and the main parameters in the FGCD algorithm. As experimental results, FGCD algorithm successfully detecting four contact phases is developed, and validation of performance of the FGCD algorithm is also implemented. Practitioner Summary: In this research, it was demonstrated that the four contact phases of Heel strike (or Toe strike), Full contact, Heel off and Toe off can be independently detected regardless of the walking speed and walking terrain based on the detection criteria composed of the ranges and the rates of change of the main parameters measured from the Inertial Measurement Unit sensors.

This paper shows that redundant actuation can reduce the energy consumption of parallel mechanisms, in some cases by a considerable margin. A theoretical analysis for the energy-saving mechanism is elucidated, and an energy consumption model for a servo-motor system is proposed. Our hypothesis is experimentally verified with a widely used two degree of freedom parallel mechanism design driven by three actuators. Experimental results show that redundant actuation can reduce the electrical energy consumption of the actuators by up to 45% compared to the corresponding nonredundantly actuated version of the mechanism.

The design of a new robotic orthosis to fully assist various overhead operations in the shipbuilding industry is proposed, and a dynamics simulation and an experimental study are conducted to validate the performance of impedance control of the new orthosis. There are considerable payloads from cables and reaction forces from injection parts during the blasting cleaning and painting in the shipbuilding process, and these can lead to work-related musculoskeletal disorders in the shoulder and elbow joints. Thus, in this research, the entire robotic orthosis designed for the dynamics simulation consists of joints with a total of 6 degrees of freedom (DOF): a 2-DOF shoulder, a 1-DOF elbow, and a 3-DOF wrist. The equations of motion of the designed robotic orthosis have been obtained on the basis of a relative-coordinate formulation. The contact force between the robotic orthosis and the human hand, gravitational force, and the control forces were considered as external forces. The results of the dynamics simu...

In this paper, details of the uses of various robots in the shipbuilding process are provided, with an emphasis on newer developments and applications. The current state of robot applications will be discussed according to the priority of the shipbuilding process. First, various robots for open structures, such as several types of welding carriages and 6-axis articulated robot manipulators, will be reviewed in terms of their mechanisms and applications. Second, several attempts to design autonomous mobile robotic systems for closed blocks of the double-hulled structure of a ship will be discussed in terms of the performance characteristics of their proposed self-traveling mechanisms. Lastly, all corresponding technologies for overcoming structural complexities in closed blocks as well as future directions of robot automation in the shipbuilding industry are also discussed.

Proximity sensor networks are aimed at estimation kinematic state of target using estimated position of the target by each sensor node or target parameter. To analyze the kinematic state of target, traditional approaches require detections on multiple sensors, very large number of sensors to achieve acceptable performance. In this paper, we propose a novel method which can estimate predicted position of the underwater target using minimum proximity sensor with bearing information to this problem. The proposed algorithm was verified performance through simulation.

This paper presents a novel meso-scale vapor compression refrigeration system (mVCRS) consisting of an evaporator, a compressor, a condenser and an expansion nozzle. First, the micro channel evaporator is designed in order to ensure the robustness to the flow rate as well as the cooling load. The film-wise condenser is then built to increase the convective heat transfer coefficient between heat pipes and the refrigerant. In spite of its compact size, the proposed rotary vane type meso-scale compressor can achieve the high pressure ratio of 3.07 and the large flow rate of 10 L per minute (LPM), respectively. The passive type expansion nozzle is adopted due to its simplicity in this research and designed to maintain a constant superheat at the outlet of the evaporator. By tactfully stacking all components, the meso-scale vapor compression refrigeration system is successfully constructed, whose overall size is 60 × 60 × 100 mm 3 (width × length × height). Through extensive experiments, it is validated that the proposed mVCRS can keep the temperature of heat source around 46 °C with the maximum cooling capacity of 80 W, and that the average coefficient of performance (COP) is up to 2.15.

This paper proposes the design and validation of a new hermetic controller for mobile robots working in a hazardous environment. Two years ago, we obtained very successful results with regard to the development of the new mobile robot RRX, which can weld, blast, and paint double-hulled structures during the shipbuilding process. At that time, some attempts were made to design a modular and hermetic controller to secure a robust cooling performance and dustproof quality because the temperature is 40–50 °C during the summer, and such operations produce considerable amounts of metallic dust such as fumes. This naturally represents a very hazardous environment for the robot's controller, for which the temperature should be maintained at its rated level, and the body should be kept fully airtight to prevent the inflow of metallic dust. Thus, in that research, heat pipes were successfully adopted to satisfy these design constraints by dissipating the heat from the servomotor drivers and several power units without any airflow into the controller for cooling. The proposed cooling system is composed of heat pipes, cooling fins, fans, and L-shaped brackets for transferring the produced heat from the heating resources to the heat pipes. Experiments were performed in the field to obtain information on the motor driver's heating value and work site temperatures as boundary conditions of the heat transfer problem, and a modular and hermetic controller for mobile robots working in hazardous environments was successfully developed and validated. The obtained experimental results fully support the idea that this design is appropriate for the controller to maintain a stable performance in a harsh environment.

There has been rapidly growing interest in hybrid quantum devices involving a solid-state spin and a macroscopic mechanical oscillator. Such hybrid devices create exciting opportunities to mediate interactions between disparate qubits and to explore the quantum regime of macroscopic mechanical objects. In particular, a system consisting of the nitrogen-vacancy defect center in diamond coupled to a high quality factor mechanical oscillator is an appealing candidate for such a hybrid quantum device, as it utilizes the highly coherent and versatile spin properties of the defect center. In this paper, we will review recent experimental progress on diamond-based hybrid quantum devices in which the spin and orbital dynamics of single defects are driven by the motion of a mechanical oscillator. In addition, we discuss prospective applications for this device, including long range, phonon-mediated spin-spin interactions, and phonon cooling in the quantum regime. We conclude the review by evaluating the experimental limitations of current devices and identifying alternative device architectures that may reach the strong coupling regime., Comment: 28 pages, 11 figures, 1 table. To appear in Journal of Optics special issue on nano-optomechanics

The recent maturation of hybrid quantum devices has led to significant enhancements in the functionality of a wide variety of quantum systems. In particular, harnessing mechanical resonators for manipulation and control has expanded the use of two-level systems in quantum information science and quantum sensing. In this letter, we report on a monolithic hybrid quantum device in which strain fields associated with resonant vibrations of a diamond cantilever dynamically control the optical transitions of a single nitrogen-vacancy (NV) defect center in diamond. We quantitatively characterize the strain coupling to the orbital states of the NV center, and with mechanical driving, we observe NV-strain couplings exceeding 10 GHz. Furthermore, we use this strain-mediated coupling to match the frequency and polarization dependence of the zero-phonon lines of two spatially separated and initially distinguishable NV centers. The experiments demonstrated here mark an important step toward engineering a quantum device capable of realizing and probing the dynamics of non-classical states of mechanical resonators, spin-systems, and photons., Comment: 41 pages, 11 figures

Many wheelchair users are accompanied by an attendant, but most prior studies did not consider this fact. This study investigated effects of ramp slope on wheelchair velocity and subjective discomfort considering both the wheelchair occupant and the attendant while ascending with the occupant facing forward, descending with the occupant facing forward, and descending with the occupant facing backward. Forty (20 male, 20 female) participants were dividing into four groups: male – male (attendant – occupant), male – female, female – male, female – female. To evaluate the usability of the ramp, analysis considered the four levels of user group and five levels of the ramp slope (1:6, 1:8, 1:10, 1:12 and 1:14) as independent variables, and mean wheelchair velocity, attendants’ physical discomfort, and occupants’ psychological anxiety as dependent variables. Considering the opinions of both the attendant and the occupant, 1:12 was recommended as the appropriate ramp slope. Furthermore, when descending a ramp, the occupant should be able to look forward.

With the progress of both wire and wireless home networking technology, various projects on smart home have been carried out in the world (Harper, 2003), and at the same time, new approaches to interact with smart home systems efficiently and effectively have also been investigated. A gesture-based interface is one of these approaches. Especially with advance of gesture recognition technologies, a variety of research studies on gesture interactions with the functions of IT devices have been conducted. However, there are few research studies which suggested and investigated the use of gestures for controlling smart home appliances. In this research the gestures for selected smart home appliances are suggested based on a user centered approach. A total of thirty-eight functions were selected, and a total of thirty participants generated gestures for each function. Based on the Nielsen (2004), Lee et al. (2010) and Kuhnel et al. (2011), the gesture with the highest frequency for each function (Top gesture) has been suggested and investigated.

For ergonomic design and product evaluation, a digital human model simulation (DHMS) system is widely used in many areas. In this study, a systematic method was proposed to create dynamic motions of digital human model (DHM) in the RAMSIS software, one of the DHMS systems and a case study was implemented to create ingress and egress motions in a car mockup; a motion capture system collected the trajectory data of markers attached to the participants’ body parts. In the RAMSIS software, a digital human model, “Manikin,” was created with their anthropometric data. Also, the dynamic motions of Manikin were created by the Actor and the Character, DHMs from another DHMS system (MotionBuilder) by using the trajectory data of its joint points. In a case study, participants performed experiments to enter and exit the car mockup with 37 markers attached to their bodies for the motion capture system. Through the proposed systematic method, ingress and egress motions of its Manikin were successfully created.

The welding task in double-hulled structures in shipyards and in steel-frame structures is hazardous and difficult due to the toxic gas and limited workspace. Therefore, many efforts have been undertaken for automation. The main challenge for automation is the development of a simple and robust seam-tracking algorithm that can be applied to a portable welding robot that operates under irregular and diverse task conditions in the workspace. We developed a seam-tracking algorithm for weaving weld path planning using a laser displacement sensor. The goal of the proposed algorithm is to detect the seam of single-butt welding with manually tack-welded non-zero gaps. The focus is on keeping the algorithm simple and affordable so that it can be applied to portable robots that operate in hazardous fields. The algorithm consists of four steps: scanning, filtering, generation of the reference points, and path planning. In the scanning process, the depth data of a cross-section of the seam profile is obtained. Next, a Gaussian filter is used to remove noise from the raw data. A differential characteristic-point detection algorithm is applied to the filtered data to detect the reference points that represent the shape and location of the gap to be welded. Finally, path planning for single-V butt multi-pass welding is done based on the detected reference points. A portable four-axis welding robot is built using the developed algorithm. The algorithm is validated through welding experiments regarding a single-V butt welding task with a manually tack-welded non-zero gap.

Target expansion, i.e., the increase of target size according to cursor movement, can be a practical scheme to improve the usability of target-selection tasks using a mouse. This study examined the effects of different user age groups and target-expansion methods on target-acquisition tasks with grouped icons. Twenty-eight subjects performed acquisition tasks under eight experimental conditions: combinations of four expansion areas (no, one-icon, fish-eye, and group expansion) and two expansion techniques (occlusion and push). Older users took longer to acquire targets than younger users; however, they showed no significant difference in accuracy. Target expansion did not substantially improve performance speed compared to the static condition. However, the error rate was lowest when group area was expanded with the push technique, and both age groups were most satisfied with one-icon area expansion with the occlusion technique. We suggest alternative guidelines in designing target-expansion schemes.

Over the last few decades, there have been a large number of attempts to automate welding in the shipbuilding process. However, there are still many non-automated welding operations in the double-hulled blocks, even though it presents an extremely hazardous environment for the workers. And, the hazards come about mainly because of the dimensional constraints of the access-hole. Thus, much effort has been recently directed toward the research on compact design of the fully-autonomous robot working inside of the double-hulled structures. This paper describes the design, integration, simulations, and field testing trials of a new type of welding robotic system, the RRXC, which is composed of a 6-axis modularized controller, a 3P3R serial manipulator, and an auxiliary transportation device. The entire cross section of the RRXC is small enough to be placed inside the double-hulled structures via a conventional access hole of 500x700mm^2, from the outside shipyard floor. The weight of the manufactured RRXC is 60kg, with a 6-axis manipulator and modularized controller, and the weight of an auxiliary transportation device is 8kg, with a 2.5m steel wire of [email protected] Throughout the field tests in the enclosed structures of shipbuilding, the developed RRXC has successfully demonstrated welding functions without the use of any additional finishing by manual welders, and has shown good mobility using an auxiliary transportation device in double-hulled structures.

Various products and patents have been established with regard to telescopic mechanisms over a long period of time. However, to the best of our knowledge, with reference to motional characteristics, few studies have been reported on a telescopic mechanism that is capable of bidirectional extension. Moreover, as we wish to point out here, such a kind of mechanism has received little attention due to the absence of practical applications. However, in the case of blast-cleaning and painting in double-hulled structures in shipbuilding, the bidirectional-extension mechanism seems to be a worthwhile subject for investigation since it will be of great help in the execution of suggested tasks for the entire transverse web floor with a range of 2–3 m. Since the self-traveling robotic platform is located on longitudinal stiffeners whose heights range from 400 to 800 mm, the manipulator to be installed on the robotic platform should have a bidirectional stroke to continuously approach the upper and lower sections of...

article i nfo Article history: Accepted 22 July 2010 The aim of this paper is to propose the design, simulation, manufacture, and experimental validation of a new robotic system for fully automated blast cleaning in the double-hulled block. The entire robotic system consists of a new type of manipulator for the blast cleaning of the entire transverse web floors, and a specially developed 6-dof RRX mobile platform for self-traveling within the application area. The full cross section of the robotic system should be small enough to be placed inside the double-hulled structure, via a conventional access hole of 600×800-mm, from the outside shipyard floor. Moreover, the maximum height of the structures has a range of, typically, 2-m to 3-m, and the robotic platform is able to be located on the longitudinal stiffeners at a height range from 400-mm to 800-mm. Thus, the investigation of a customized manipulator, having a bi-directional stroke in order to approach the upper sections, is a most worthwhile subject in the automation of the shipbuilding process since such a system should be capable of carrying out continuous blast cleaning from the upper to the lower sections at one time, without the need for any additional operations. Throughout the field testing, significant results have been obtained, indicating that the new proposed system can successfully perform continuous blast cleaning for the entire transverse web floor and the longitudinal stiffeners without any dynamical instability of the robot platform. Proposed robotic platform, will bring great benefits to ship yard automation.

This study examined perceived discomforts encountered in residential facilities such as individual houses and apartments, and suggested a procedure for improving the problems in the living residence. The participants consisted of two groups of people: normal and underprivileged people; the underprivileged group was classified into 3 sub-groups: elderly people (over 65 years old), handicapped people and pregnant women. To identify inconvenient places and design factors in the residential housing, a total of 200 subjects (50 for each group) participated in the survey using the 7-point Likert scale. As a result, all the user groups mainly answered a high degree of discomfort due to narrow parking places, doorsills, and height differences between floors. The elderly, the handicapped, and the pregnant women replied that it is uncomfortable to use ramps and utility rooms. In a follow-up study, one-to-one in-depth interviews were conducted with some of the participants to analyze the detailed causes of inconvenient places and design factors. This study also suggested the procedure for solving the problems in various design factors from perspective of universal design, by considering prior studies which focused on a certain user group like the elderly. This procedure was suggested to consider as many user groups as possible at the same time. The results can be used to understand the discomforts of various user groups on residential housing. The procedure can also be used to develop universal design guidelines for the living residence.

Recent advances in nanorobotic manipulation of ferromagnetic nanowires bring new avenues for applications in the biomedical area, such as targeted drug delivery, diagnostics or localized surgery. However, probing a single nanowire and monitoring its dynamics remains a challenge since it demands high precision sensing, high-resolution imaging, and stable operations in fluidic environments. Here, we report on a novel method of imaging and sensing magnetic fields from a single ferromagnetic nanowire with an atomic-scale sensor in diamond, i.e. diamond nitrogen-vacancy (NV) defect center. The distribution of static magnetic fields around a single Co nanowire is mapped out by spatially distributed NV centers and the obtained image is further compared with numerical simulation for quantitative analysis. DC field measurements such as continuous-wave ODMR and Ramsey sequence are used in the paper and sub Gauss level of field sensing is demonstrated. By imaging magnetic fields at a single nanowire level, this work represents an important step toward tracking and probing of ferromagnetic nanowires in biomedical applications.

This paper describes the development of a self-driving mobile welding robot. The robot is used to weld U-shaped welding areas in enclosed double-hull structures. In order to place itself inside the double-hull structure, the robot is capable of passing through an access hole 600 mm wide and 800 mm high. This research addresses the mechanical and control systems of the robot. The mechanical system of the robot consists of an eight-axis mobile platform, and a six-axis welding unit. The control system consists of a main controller, a welding machine controller (arc sensor board), and seam tracking sensors, i.e., a touch sensor, a laser sensor, and an arc sensor. To reduce the number of cables that would be dragged by the welding robot, the main controller is designed as an embedded type that is mounted on the back of the mobile platform.

Shipbuilding processes involve highly dangerous manual welding operations. Welding ship walls inside double-hulled structures presents a particularly hazardous environment for workers. This paper describes the ''Rail Runner X'' (RRX), a new robotic system that can move autonomously inside the walls of a double-hulled ship and automatically execute the required welding processes. The RRX robotic system is composed of a mobile platform and a welding robot consisting of a 3P3R serial manipulator. The robot is used to weld U-shaped trajectories located between two longitudinal stiffeners. The mobile platform enables traverse movements onto neighboring longitudinal stiffeners. The entire cross section of the robotic system is small enough to be placed inside the double-hulled structure via a conventional access hole from the outside shipyard floor. The overall engineering design process that led to the final robot solution developed is presented in this paper, including kinematic analysis data and experimental results for verifying the autonomous movement and welding performance.

This study investigated the effects of age and two keypad types (physical keypad and touch-screen one) on the usability of numeric entry tasks. Twenty four subjects (12 young adults 23–33 years old and 12 older adults 65–76 years old) performed three types of entry tasks: 4-digit, 4-digit of password type, and 11-digit. The dependent variables for the performance were mean entry time per unit stroke and error rate. Subjective ratings for ease of use of each keypad type were collected after the experiment. The mean entry time per unit stroke of the young adults was significantly smaller than that of the older adults. The older adults had significantly different mean entry times per unit stroke on the two keypad types. The error rates between young and older adults were significantly different for the touch-screen keypad. The subjective ratings showed that the participants preferred the touch-screen keypad to the physical keypad. The results showed that the older adults preferred the touch-screen keypad and could operate more quickly, and that tactile feedback is needed for the touch-screen keypad to increase input accuracy. The results of this study can be applied when designing different information technology products to input numbers using one hand. Relevance to industry Touch-screen technology is increasingly used in ticketing Kiosks used in public places such as airports, stations or theaters, and in automated teller machines (ATMs) and cash dispensers (CDs). This paper can be applied to design these products or systems, particularly considering usability improvements for older adults.

This study investigated the availability and safety concerns of the conventional and prospective propulsion systems for LNG carriers: • dual-fuel steam turbine mechanical (DFSM) propulsion, • dual-fuel diesel electric (DFDE) propulsion, • dual-fuel gas turbine electric (DFGE) propulsion, • dual-fuel diesel mechanical (DFDM) propulsion, and • diesel mechanical propulsion with reliquefaction (SFDM+R). The two prospective candidates, the DFDM and DFGE, exhibited the availabilities of design and emergency propulsion loads as high as the newly adopted DFDE and SFDM+R, while the DFSM demonstrated the highest. All the propulsion systems achieved a satisfactory level of the availability for the BOG utilization. The newly introduced dual-fuel systems of DFDE, DFDM, and DFGE accompanied new hazards due to their need for pressurized fuel gas supply. The failure modes caused by these hazards were identified, and feasible safe guards were suggested. The hazards of fire and explosion stemming from flammable gas leak were considered to be acceptably mitigated by the safety requirements from the current industrial standards and classification society.

‘Seoul National University’ and ‘Daewoo Shipbuilding & Marine Engineering’ in Korea jointly developed a mobile welding robot, the ‘Rail Runner’ (RRX), which is able to freely move in both transverse and longitudinal directions, and perform welding tasks in double hull structures. Recently, RRX2, (the second version of RRX), was presented at ‘Robotics and Applications 2007'. In this paper, the design, manufacturing, and application of RRX3, the third version of RRX, is described. The moving mechanism of RRX, which is able to move freely in a double hull structure, has two functions. 1) To move in a longitudinal direction by driving wheels using longi. faces as ‘rails', and 2) To move in a transverse direction by sliding along supporting longi. faces using extension arms. The body of the RRX3 is composed of a 12-axis, 6-axis mobile platform that supports the RRX moving mechanism and a 6-axis welding robot to do the welding job. The main point in designing RRX3 is to make it capable of passing through a 600mm×800mm sized access hole, the entrance into an enclosed double hull structure. The full size of the manufactured RRX3 is 1825mm×495mm×569mm, and thus the RRX3 is able to pass through an access hole. The weight is 250kg with a 6-axis mobile platform, 6-axis welding robot, and mounted controller.

Optimization and control of stiffness for parallel kinematic mechanisms (PKM) are critical issues because stiffness is directly related to the precision and response characteristics of the end-effector of PKMs. Unlike nonredundant PKMs, redundant PKMs have additional actuators exceeding their essential degrees-of-freedom (DOF), resulting in an increase in the redundancy of control. The stiffness of redundant PKMs is divided into passive and active stiffness. Active stiffness is changeable even in cases of fixed kinematic parameters and end-effector posture. However, it is not easy and intuitive to control the active stiffness of redundant PKMs for the complexity of Hessian matrix operations. This paper describes a new decoupling method for explicit stiffness analysis of redundant PKM with the well-known two-DOF and one-redundant planar five-bar PKM. Three actuating joints are decoupled to three groups containing two actuating joints. With this mathematical configuration, the stiffness matrix for one-redundant actuation is also divided into three stiffness matrices for nonredundant actuation, and the contribution of each actuator can be intuitively investigated. Stiffness matrices for the original and decoupled cases are compared in detail. In particular, this decoupling method is applicable to redundant PKMs with many passive joints. Finding optimal joints for one- or two-redundant actuation with various candidates is more intuitive with this decoupling method.

Recently, cryogenic butterfly valves for LNG carriers are actively developed by ship equipment companies. The dual core structure unlike usual butterfly valve has both translation and gyration motions of the disk of the valve assembly. Especially, the ship equipment companies can not have overcome 2D design method; in addition, even though 2 years of development has passed, the drawing cannot be secured. In this research, for the cryogenic butterfly valves and the product design, 3D design method was introduced and DMU(Digital Mockup) was applied to complement the problems in 2D design and investigate application possibility of 3D design method.

This study is focused on the skill to prevent RIB (Rigid Inflatable Boat) from sinking. For better ability to prevent sinking, single hypalon tube is replaced by double TPU (Thermoplastic Polyurethane) tube that is excellent at frictional wear strength and oil-resisting qualities. High buoyant materials are arranged in empty spaces of ship so that ship`s spare buoyancy is increased. And for restoration of stable position of ship, the self-righting system is installed. Aluminium alloy is used for increasing hull strength.

A program to predict the transient characteristics of the heat recovery steam generator (HRSG) is constructed and the start-up behavior of the high-pressure part of an HRSG is analyzed with a special focus on the estimation of the thermal stress in the steam drum. Three HRSG start-up procedures (steady gas turbine without gas bypass, steady gas turbine with gas bypass, start-up gas turbine) are simulated. The gas bypass is conducted during the initial stage of the start-up. Estimation of the maximum thermal stress makes it possible to optimize the gas bypass mode. It is shown that bypassing part of the gas flow lowers the peak stress much in case of the steady gas turbine exhaust condition. Examples of the scheduling of the gas flow increase using the step and ramp modes are demonstrated. In case of the simultaneous start-up, the peak stress is considerably low due to the gradual increase of gas temperature and mass flow and bypassing just a small portion of gas flow is enough to keep it under the allowable limit.

Oleic acid, polymethyl methacrylate, and polyacrylic acid were coated on soda-lime-silicate and silica glasses from ethyl alcohol, benzene, or water. The structural interaction of each organic compound with the surfaces of the glasses is determined on the basis of varying coating conditions such as solvent, composition of the glass, the coating (adsorption) time and the aging time in air. Metal chelates are identified in the organic coatings on the soda-lime-silicate (SLS) glasses. For oleic acid coatings on the soda-lime-silicate glass developed from benzene, sodium oleate is the dominant species, while for coatings from ethyl alcohol, the formation of calcium oleate increases. Aging the coating in air produces additional sodium oleate. Increasing coating time increases the formation of calcium oleate. Addition of Al2O3 into the glass or coating TiO2 onto the glass alter the interaction mechanisms for oleic acid, and improves the durability of the coating. Polymethyl methacrylate produces less metal-chelate bonds on the SLS glass surface than oleic acid due to the presence of a CH3 group in the COOCH3 unit. Coated polyacrylic acid possesses different configurations with different pHs of the preparation solution. Thus, the surface structural interaction of the organics is closely related to the metal ions on the glass surface possessing high mobility as well as the bonding strength of the organics with adsorption sites on the glass surfaces.

Small‐size turbojet engines have difficulties in maintaining the chemical reaction due to the limitation of chamber size. The combustion chamber is generally designed to improve the reaction efficiency by the generation of vortices in the chamber and to enhance air‐fuel mixing characteristics. In the initial stage of designing the combustor, analysis of the 3‐D full configuration is not practical due to the huge time consuming computation and grid generation followed by modifications of the geometry. In the present paper, an axisymmetric model maintaining geometric similarity and flow characteristic of 3‐D configuration is developed. Based on numerical results from the full 3‐D configuration, model reduction is achieved toward 2‐D axisymmetric configuration. In the modeling process, the area and location of each hole in 3‐D full configuration are considered reasonably and replaced to the 2‐D axisymmetric model. By using the 2‐D axisymmetric model, the factor that can affect the performance is investigated with the assumption that the flow is non‐reacting and turbulent. Numerical results from the present model show a good agreement with numerical results from 3‐D full configuration model such as existence of vortex pair in forward region and total pressure loss. By simplifying the complex 3‐D model, computing time can be remarkably reduced and it makes easy to find effects of geometry modification.

Welding is very difficult and dangerous for manual welders. The double hull structures found in ships are very hazardous environments, and as such the shipbuilding industry demands a safer, autonomous system to perform the welding rather than deploy manual welders. This paper describes the design of a new mechanism, called the 'Rail Runner', which is able to autonomously travel within the double hull structure. The design of a 3P3R serial manipulator for welding is also described in this paper. As an application of the 'Rail Runner' mechanism, we combine the 'Rail Runner' platform and the 3P3R serial manipulator for autonomous welding. The mechanical system of this robot is composed of a six-axes (3P3R) manipulator for achieving the welding function and a six-axes mobile platform for traveling within the double hull structure. This robot is able to autonomously travel between longitudinal structures, with transverse direction, and is capable of welding in double hull structures. The 'Rail Runner' can raise the efficiency of the welding process, as compared to manual welders. This in turn raises the international competitiveness of the shipbuilding industry.

Typical sensor networks consist of a user, a sink, and a number of sensor nodes. The traditional communication architecture usually assumes that there is a legacy networks between a user and a sink. However, in many actual applications users like firefighters and soldiers move around sensor fields and they may not have any direct communication through legacy networks. In other words, a sensor network is the only communication channel between a user and a sink in a practical sensor field. Thus, it is essential to deliberate a novel architecture for the user mobility issue. In this paper, we present a novel communication architecture where a user operates around an infrastructureless sensor field. We, then, propose a new networking model to support user mobility on the novel architecture, named dynamic sink model. In the model a sink is temporarily selected among generic sensor nodes by a user when the user wants to get information from a sensor network. The selected sink gathers data from sensor nodes for interested tasks and propagates collected information to the user via the sensor network. We evaluate and analyze performance of the proposed dynamic sink model on the novel architecture with regard to efficiency of energy consumption, average delay, and delivery ratio, compared with the common static sink model on typical communication architecture

This study examined the safety and environmental issues encountered in the course of development of a closed-circuit LNG regasification system to be installed on offshore LNG terminals or regasification shuttles. Restriction on sea water usage as the heating medium intrinsically determined that the developed system should be based on a closed circuit assisted by steam-generating boilers. Care were taken in establishing the operation and control philosophy, not to generate any residual steam that needed inevitably to be condensed with sea water or to be vented to the atmosphere. One of the most critical hazards was the huge amount of blowdown gas in case of emergency shutdown. It was found that the discharge through a vent mast still left a considerable risk due to the gas dispersion around the facility. Instead, a restricted blowdown to the LNG containment system or a combustion unit resulted in a less risk with a prolonged duration. Rigorous studies were performed to quantify the risks and to anticipate the system behavior. The leak and fire risk analysis indicated that the system had significantly low frequency of fire and explosion compared with usual offshore facilities. However, any guidelines were not available to assess the risk quantitatively. The process dynamic simulation suggested how the system should be shut down. This study showed that several critical challenges were solved successfully and the risk level of the closed-circuit regasification system was acceptable.Copyright © 2007 by ASME

A robot soccer match poses an interesting problem in planning: the planning of coordinated motion of individual players as a team, against the opponent players the next move of which is not known a priori, in such a way as to achieve the common goal, i.e. winning the match. The outcome of a soccer match depends largely on how well the motions of individual players of a team are coordinated against those of the opponent. The technical challenge lies in formulating such coordination strategy together with computational formalism that allows a real-time search for an optimal coordinated motion of individual players. In this paper, we propose the concept of the "controllable zone" of a player or a team, representing the area or the set of field positions that the player or the team can occupy before the opponents at time t. A systematic way of computing various forms of controllable zone is presented. Based on the formalism of controllable zone, it is possible to identify whether a team should be in an offensive or a defensive mode, and which strategy among shooting, capturing, dribbling, and passing is desirable for the team at time t. The coordinated motions of individual players are then determined in such a way as to optimize the strategic scores associated with controllable zones. The proposed paradigm is applied to a real environment for animated simulation: 3/spl times/3 FIRA World Cup micro robot soccer match, to evaluate its performance.

Abstract This study presented the dynamic simulation of a gas compression system, proving the viability of operational philosophy and emergency shutdown logic with quantitative process responses in various situations. To avoid unnecessarily high peak in an initial stage of blowdown, this study employed the controlled blowdown and investigated its safety level. Introduction This study concentrated on the dynamic simulation of a gas compression system of a topside module on offshore facilities. The gas produced from the wells was separated in the Inlet Separator and routed to the Gas Compression Module. Such various process specifications and operation logics as dew-point control, turbine speed, and compressor surge were taken into account in the dynamic simulation. Revealing the time-varying behavior provided the viability of operational philosophy and emergency shutdown logic, illustrating the detail and quantitative process responses to various disturbances. For example, it showed the transient behavior of the compressor control system consisting of the recycle valve opening at 15% above the surge flow and the surge control valve opening at 10%. Event scenarios included the possible cases of emergency and relief operation. The history of such process variables as pressure, temperature, liquid level, and flow rate were demonstrated to the virtual event scenarios. Flare system should be designed to the peak flow rate. The conventional blowdown systems is easy to install and simple to operate. But, it suffers an unnecessarily high peak flow rate in an initial stage of blowdown. In offshore processes, this high peak rate means costly flare facilities. Especially, the flare stack location and weight distribution demand careful consideration for floating units like FPU, FPSO, and LNG FPSO. Therefore, it is important to mitigate the peak flow rate for environmental protection and optimization of the flare system design. In addition to rigorous dynamic simulation, this study also examined the feasibility of the controlled blowdown application to the floating units, to decrease the peak flow rate. The blowdown system was compared with the normal practice in terms of safety level as well as of flare load. Process description The gas compression and treatment facilities are rated for gas export capacity of 60 MMscfd and fuel gas requirement of 4 MMscfd at 108 F ambient temperature and 100 % relative humidity. The overall compression requirement is satisfied by two process stages. The Low Pressure (LP) and the Intermediate Pressure (IP) stages are in the form of a complete 100% train, comprising a single driver with two compressors in a tandem arrangement. The gas turbine for LP and IP Compressors is capable of running both on fuel gas and diesel. Diesel is to be used only for field 'black start' when fuel gas is not available. The discharge pressure of the IP compressor is fixed at 638.5 psia (43 barg) to fulfill the required hydrocarbon dew point specification. The compression module receives the gas from the Inlet Separator, the gas produced from the wells is separated into two phases of gas and liquid. Compression is performed in two stages increasing the pressure from the Inlet Separator operating pressure to the required export discharge pressure.