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This paper investigates how to improve the compactness of a Synchronous Permanent Magnet Surface Mounted machine for high-frequency and high torque direct-drive applications. For that, the performances such as power mass density and losses of different pole patterns, e.g. Halbach and conventional radial magnetized magnet arrays are compared. Depending on the given specifications, some considerations concerning the decision-making process, taking into account process and assembly constraints when choosing between the conventional radial magnetization and the Halbach array, are reported.

Joints’ backdrivability is desired for robots that perform tasks contacting the environment, in addition to the high torque and fast response property. The electro-hydrostatic actuator (EHA) is an approach to realize force-sensitive robots. To experimentally confirm the performance of a biped robot driven by EHAs, we developed the fully electro-hydrostatically driven humanoid robot Hydra. In this paper, we evaluate the whole-body control performance realized by integrating encoders, pressure sensors, and IMU through a high-speed communication bus to the distributed whole-body control system. We report the first example of bipedal locomotion by an EHA-driven robot in both position-controlled and torque-controlled approaches. The robot could keep the balance even when the ground condition was changing impulsively and utilize its high joint backdrivability to absorb a disturbance by the null space compliance. We also report practical challenges in implementing compliant control in real hardware with limitations in parameter accuracy, torque, and response. We experimentally confirmed that the resolved viscoelasticity control (RVC), which has indirect feedback of operational space tasks by projecting the operational space feedback gain to the joint space one, was effective to tune a proper gain to stabilize the center-of-mass motion while avoiding joint-level oscillation invoked by the control bandwidth limitation. The attached multimedia file includes the video of all experiments presented in the paper.

The axial flux with amorphous alloy stators has the virtues of high power density, high torque density, compact structure. But specific to the disadvantage of restricted space of in-wheel, the compact axial flux in-wheel motor was proposed in this paper. The in-wheel motor’s performance affects the dynamic and security of electric vehicles directly. And the electromagnetic loss has a significant impact on in-wheel motor performance. To demonstrate the influence of electromagnetic loss on the thermal behavior of the machine, thermal analyses employing magneto-thermal coupling simulations have been performed. Then the experimental prototype was manufactured and tested. The simulation of the output power model was verified by test value, proving that the magneto-thermal coupling simulation is feasible. Therefore, this design technique provides a reference for the in-wheel motor structure.

In this paper, topologies for fully superconducting machines are analyzed. Then, a novel fully superconducting machine topology-fully superconducting geared machine is developed. The proposed topology is featured with contactless torque transfer capability and high torque density. Furthermore, the performances, such as back electromotive force and torque waveform, and performance comparisons between proposed machine and typical fully superconducting machine are done. It is found that the proposed topology could obtain much higher torque density than that of the typical fully superconducting machine. Meanwhile, its auxiliary components, such as seals, dewar, become much simpler due to its contactless torque transfer capability.

Background and objective: The purpose of this study was to evaluate the torque insertion for drill and non drill techniques of two commercially available miniscrews. Methods: Eighty mini screws (forty Dentos miniscrews/Korea and forty 3M miniscrews/USA), having the same length and diameter, were divided into two groups for each type. Two techniques, non-drill and drill, were used. In drill techniques, manufacturer recommended drill was used. Two bovine tibias were obtained. The first technique used pre drill hole, which was made in the bone using the recommended bur (1.0 diameter). The mini-screw was placed at 9 mm manually, then the remaining 1 mm was inserted through digital torque meter. The same procedure was repeated but without a pilot hole. Results: 3M miniscerws gave high torque insertion in two techniques. Conclusion: The shape, thread design and tip geometry of miniscerw play an important role in the torque insertion.

The objective of this study is to compare bone-to-implant contact (BIC) between implants inserted at high torque due to under-drilling of the crestal bone to those inserted at low torque due to over-drilling of the crestal bone.Forty implants with diameters of 3.75 mm (group A) or 3.55 mm (group B) were inserted in the proximal tibiae of NZW rabbits in two separate surgeries on day 0 or 21. Osteotomy of the crestal bone was finalized with a 3.65-mm drill. In group A, implants were inserted at torque ≥35 Ncm (under-drilling) and in group B with torque10 Ncm (over-drilling). Implants and their surrounding bone were retrieved on day 42, thus creating 3- and 6-week observation periods, processed for non-decalcified histology and stained with toluidine blue. Crestal BIC (c-BIC) and total BIC (t-BIC) were measured. Wilcoxon test was used to evaluate differences between groups.Three weeks post-surgery, the mean c-BIC in group A was 16.3 ± 3.3 vs 31.5 ± 3.4 % in group B (P 0.05). At 6 weeks, a similar trend was observed (group A: 28.7 ± 3.6 %; group B: 38.4 ± 4.9 %) (P 0.05). No differences in t-BIC were noted at 3 weeks and at 6 weeks between the groups.Insertion of implants with an over-drilling protocol of the crestal aspect of the osteotomy resulted in increased short-term crestal bone-to-implant contact.Insertion of implants with a high torque following an under-drilling protocol, commonly used for immediate loading, may reduce crestal bone-to-implant contact at early healing stages.

This research investigates a novel concept in small-scale wind-energy generation. Instead of rotating turbine blades, the present concept produces reciprocating motion that is achieved by alternately activating boundary layer control (slot blowing) on opposite sides of a circular cylinder. This is commonly called the Coandă-effect, and here we deploy it periodically on a spring-stabilized vertical cylinder, to produce reciprocating motion. This Co andă-based Re ciprocating (CoRe) system converts wind energy to mechanical work. Compared to wind turbines and windmills, the CoRe system generates higher torque and is therefore well suited to directly driving positive displacement pumps for drip-irrigation or reverse osmosis water desalination. This new approach necessitates the investment of energy in order to extract energy from the wind and therefore a major challenge is to maximize the output/input ratio in order to render the concept viable. Previous preliminary wind tunnel tests conducted on the CoRe system produced gross and net power coefficients of 10% and 3% respectively. However, the blowing slot design has a decisive impact on output power. On the basis of data presented in the literature and our computational analysis, the CoRe system produces significantly greater torque than all types of wind turbines with net power coefficients over 10%.

A world leading ERD project was required to make a step change in drilling performance to reduce the well construction duration. An opportunity was identified to minimize invisible lost time due to handling a tapered string combing two sizes of drill pipe. The objective was to design and successfully run a new uniformed string, based on a fit-for-purpose slim drill pipe concept which is intended to offer an unprecedented robust and ultrahigh torque connection. Following an initial analysis of the drilling requirements in terms of torque, dimensions, tensile capacity and hydraulics, it was rapidly identified that the process limiter was the drill pipe connection as no option available in the market could meet the redesigned project requirements. A thorough assessment of the tool joint characteristics was performed to identify the upgrade(s) that will maximize the connection capacity and performance. As a result, the R&D team of a manufacturer was brought onboard to design the new thread that will enable the operation as planned. The new design would then be validated through shop stress tests and field trials with actual pipe. A new thread model was developed and allowed the design of drill pipe that had a reduced tool joint OD that would allow for a lower annular pressure drop and fishability in the 8 ½" hole. The tool joint provided an increased torque capacity up to 70,000 ft-lbs while still meeting the operating mandates of minimized handling and maintenance requirements. The newly designed drill pipe successfully passed the shop stress tests and was mobilized for operations. The drill pipe completed an entire well consisting of three sections (16", 12 ¼" and 8 ½") within the tight hydraulic window of such ERD wells further validating the original drilling simulation parameters. The post job drill pipe inspection confirmed that wear and tear were within current benchmarks. Furthermore, subsequent analysis showed that the connections make and break duration was better than the average experienced rates on the same rig. In addition to the technical capability of the new drill pipe, the introduction of a single size string reduced the drill pipe inventory by approximately 20% and saved close to 7 days of rig operating time on the well. This paper will present the framework used to foster innovation and the cooperation between the E&P company drilling team and the drill pipe manufacturer's R&D group. It will detail the fast-tracked introduction of a new design of drill pipe with an innovative thread type which seeks to combine efficiency, reliability and unparalleled torque capacity, in order to extend the drill string torque technical limit with the potential to revolutionize the ERD industry.

The performance of traditional humanoid robots is often limited by their design, with high DoF limbs and stiff actuation complicating their dynamics and impeding their ability to operate in unsupervised environments. In response to these deficiencies, this paper introduces the Non-Anthropomorphic Biped: Version 2 (NABi- V2), a bipedal robot that is a departure from the conventional humanoid paradigm in its morphology and actuation method. That is, NABi- V2 is a platform with a unique leg configuration that is designed around high torque back-drivable electric actuators that provide proprioception and force control capabilities. This paper details the concept and design of this system, and presents a simple yet robust compositional controller for performing in place, two-legged pronking, a form of continuous jumping locomotion that is typically realized with series elastic or hydraulic actuation.

Nanotechnology refers to the physics and control of particles at sub-nanometer dimensions, enabling atomic level manipulation, imaging and characterization. Manipulation of matter at this ultra-precision level has become ubiquitous in several genres of science and engineering, encompassing multi-faceted industrial applications ranging from biomedical to semiconductor physics. Piezoelectric ceramics have emanated to be the most promising nano-positioning actuators and plays a key role of precision mechatronic systems developed to manipulate objects over a large travel range with high torque, compact form factor, rapid response and accuracy down to a fraction of atomic radius. This research presents an overview of this interesting technology which is indispensable for accurate positioning applications highlighting upon the fundamentals of its operations, major non-linearities that hinder system performance, and control regimes to overcome the bottlenecks. The study also bridges the gap between the scientific phenomenon of piezoelectric technology and its industrial application through a comprehensive review of piezoelectric motors to highlight its importance in positioning applications, along with state-of-the-art usage of this exciting actuation principle.

For humanoid robots, design of the ankle mechanism is still open research problem since high torque is required while compact structures have to be maintained. This paper investigates an enhanced design of 3 degree-of-freedom hydraulic hybrid ankle mechanism. The design is based on (US9327785) Alfayad et al. (2011). Using a hybrid kinematic structure with hydraulic actuation, allows us to reach a slender humanoid ankle shape while enabling the high torque performances required for stable walking. Performances analysis of the first version ankle mechanism designed for HYDROiD humanoid robot showed some limits mainly induced by seal friction and pistons misalignment. In this paper, the influence of the friction parameters is explored. A virtual model is developed to evaluate the performances of a new flexion/extension and adduction/abduction pistons arrangement. Then, a control algorithm is simulated and implemented, as an example, to the flexion/extension motion of the new ankle mechanism. Finally, an experimental validation for the performances of the new proposed hydraulic ankle is conducted using the built hardware prototype, the results show significant improvement.

Wearable robots enhance the ability of their wearers to physically interact with the world, and can benefit rehabilitation efficiency, assistive devices’ effectiveness, and ergonomic support of workers. Wearable robots’ ergonomics and safety can be promoted by using actuators made of soft materials, but soft actuators in the literature are unable to produce the high torques required for lower limb activities of daily living (ADLs), for example, extension of the knee for sit-to-stand. This paper presents and validates a method for realizing a soft high torque actuator, the pleated pneumatic interference actuator, for knee extension. It was shown to produce a torque of 150 Nm at 2 bar and an angle of 70°. Future work will see the development of a portable pressure source to inflate the wearable actuator.

Induction motors are used in various applications because it has the simplest construction and design than other motor types. The applications are not only in industrial applications but also in maritime applications. This paper presents a design process for a 250 kW three-phase asynchronous motor with high torque and low rpm for electric bow thruster application. First, motor capacity is obtained based on the naval architect calculation. The capacity determination is considered ship weight and dimensions. After that, basic calculations for the motor used mathematical approaches. Those mathematical approaches are used to find out major geometries of the motors (for instance: stator coils, rotor bars, stator, and rotor core dimensions, and air gap). In addition, the air gap is one important part in motor geometry calculations. The optimum air gap distance is needed to obtain better motor performances. This paper shows the impact of air gap distance for motor performances. The motor performances are analyzed with MATLAB.

High torque density PM machines have attracted more and more attention recently, especially for the low-speed, high-torque application. In this paper, three high torque density PM machines are analyzed and compared, namely 12-slot/10-pole SPM, 16-pole transverse flux PM and 12-slot/22-pole flux modulation PM machines, with the specification of 30 kNm/m3, To reveal the nature of high torque density of different topologies, saturation effect is neglected. Based on the Maxwell stress tensor (MST) method, the radial and tangential flux density and force distribution along the airgap are illustrated. The torque contribution from different field harmonics are also compared. It's shown that torque density of PM machines can be enlarged further by improving the tangential flux density, decreasing the phase difference between radial and tangential flux density, and integrating more working harmonics into one PM machine.

Present day PMSM design methodologies often use optimization tools. Optimizing the geometry alone, may lead to designs that have high efficiency and torque density but may have high torque ripple. By injecting high frequency currents, some optimal geometries with too high torque ripple, become acceptable and optimal, even with an increase in machine and inverter losses, and a decrease in efficiency. An optimization methodology is proposed that uses an analysis of FEM sample designs and a regression model to optimize a PMSM, using a multi-objective genetic algorithm (NSGA-II) and including high frequency injection for torque ripple reduction.

This paper presents a design exercise of an interior permanent magnet (IPM) machine with high-torque overload capability. The machine is intended for traction applications, where the intermediate transient operation is one of the key design requirements, alongside with the more common specification for the continuous operating duty. The design approach frequently adopted, when considering the transient overload, focuses solely on the continuous operation with appropriate design margins. Consequently, such method is often unreliable and requires a degree of experience or multiple design iterations need to be performed. In contrast, this work proposes a technique accommodating for the transient overload from the onset of the design process. The initial machine sizing is based on a coupled electromagnetic and thermal analysis combined with an optimisation routine. The developed design-optimisation system employs computationally efficient and accurate models informed from thermal tests on representative hardware subassemblies. Further to the design challenges associated with the specific operating duty, the materials and processes used in fabrication of the machine should assure here a cost-effective design solution. The theoretical findings show that proposed method is effective for designing machines for more demanding transient overload events, where both transient specific output and its duration are simultaneously considered.

The paper presents the design of a hy-perconducting double-rotor permanent magnet synchronous machine for high torque applications by fulfilling the mechanical requirements of an all-electric helicopter. The aim to design a rotating electrical machine with high gravimetric power density goes along with different technologies, presented in the survey of this paper. Nevertheless, the usage of a promising technology is no guaranty for an optimal solution. Therefore, based on hyperconductive material, this paper discusses the challenges and investigates different design methods to come up with a final design strategy. Hence, an overview is given on how to design a hyperconductive machine, combining air windings, Halbach arrays, a double-rotor configuration and an end-winding cooling fed by liquid hydrogen.

Synchronous reluctance machine is renowned for high torque ripples due to its complicated and non-linear magnetic path and saturation of rotor core segments during operation. Improving the ripples effects in the machine is imperative for high speed applications. This study investigates and propose methods to improve torque ripples and cogging torque of synchronous reluctance machine. Conventional method and mathematical analysis used by fellow researchers are revisited in this paper and its validity is investigated using FEM. Optimization techniques specially designed for SynRM is used to verify the torque ripples of couple of designs. Cogging torque of synchronous reluctance machine is estimated using FEM in order to verify and compare special scenarios.

Position sensorless control of synchronous reluctance machines is not easy due to nonlinear correlations caused by extensive magnetic saturation. This article investigates stability of a conventional saliency-based method and, for the first time, shows that the method becomes unstable at high torque with high magnetic saturation not due to cross-coupling effect itself but due to expansion of the cross-coupling effect through feedback of the estimated position. This instability occurs even when neither disappearance of the saliency nor reversal of the estimated d - and q - axes arises. A novel method to overcome this instability is proposed, which utilizes magnetic saturation depending on current phase angles. The proposed method was verified by simulations and experiment using a prototype machine. The results demonstrated that the proposed method achieved stable sensorless operation at the maximum torque, and thus, surpassed the conventional saliency-based method, the feasible torque of which was limited to 60% of the maximum for the prototype machine.

This work deals with the analysis and design of a hairpin winding. Such a winding type is more and more used in traction motor of electric and hybrid electric vehicle. It allows a higher slot fill factor in comparison with the traditional round wire windings. This yields a high reduction of the Joule losses, when the motor is required to develop high torque, e.g., during accelerations. However, due to the high cross-area section of such rectangular-shape conductors, the current is non-uniformly distributed in the conductors, and this causes a reduction of the benefit of the higher copper area. In addition, due to the high frequency at the higher speeds, parallel paths are often required. Particular care has to be posed when such parallels are designed, with proper transposition of the wires, to avoid a non uniform distribution of the current in the parallel paths. The motor parameters are computed analytically and then validated by means of a Finite Element analysis. Satisfactory results are achieved. The additional losses are computed according to the conductor geometry and the whole winding connections (parallel paths, transposition, and so on) with a satisfactory precision.

Compared with traditional permanent magnet synchronous machines (PMSMs), dual-permanent-magnet-excited (DPME) machines belong to novel permanent magnet (PM) machines, which can offer high torque density so as to be very suitable for low-speed large-torque applications. Unlike traditional PMSMs, the pole-pair number (PPN) of armature windings is not equal to that of rotor PMs, so it is necessary to study the control strategy of the DPME machine. However, few investigations on the control strategy have been carried out, let alone a new control strategy, i.e., predictive control. The purpose of this paper is to propose a new predictive flux-linkage control (PFC) strategy for the DPME machine. The PFC strategy has been realized by building models in Simulink and the steady and transient results have validated the feasibility of the proposed PFC strategy for the DPME machine.

This paper present the design and the experimental verification of a 12-slots/10-poles interior permanent magnet synchronous machine (IPMSM) for small utility vehicle. This publication discusses the choice of the topology for a direct drive, high torque density, wide constant power speed range ratio (CPSR). Performances of the constructed prototype measured on the test bench have confirmed the finite element analysis (FEA) results.

The paper proposes a novel Linear Parameter-Varying (LPV) based control approach for the anti-lock braking (ABS) functionality of electric vehicles. Through the advanced control design the hydraulic actuation and the regenerative braking of the electric motor can be coordinated efficiently. In the proposed control architecture the advantages of the different interventions can be combined, such as the the high torque generation capability of the hydraulic system and the fast actuation of the electric motor. The results of the LPV-based control design is presented through simulations using the high-fidelity CarMaker software.

Permanent Magnet Synchronous Motor (PMSM) is compact and highly efficient, so it is widely used as a motor for Electric Vehicles (EVs) drive. However, it does not mean there is no problem at all. Applying high voltage to obtain high torque increases torque ripple. We propose a new modulation for the inverter to drive the PMSM, Modified-Trapezoidal-Modulation (MTM). The greatest advantage of MTM is that it can realize the torque increase and the torque ripple reduction at the same time. In this paper, experiments were conducted to obtain the merits of the proposed method. Results show that the proposed method generates increased torque comparing the result with other modulation techniques and confirmed that MTM reduces torque ripple by 9.27%.

There were few difficulties faced in the total indicated run out testing of industrial conveyor idlers, such as separate apparatuses for testing various sizes of idlers, human observation error occurrence due to the usage of analog dial gauges, time consuming due to manual operation for the rotation of idlers, difficulties in formulating the output manually. Considering all the difficulties faced in total indicated run out testing of idlers. Design and fabrication of the newly proposed machine is done. They can accommodate idlers up to three meters in single apparatus by using adjustable V-block in guide ways in order to counter the change of idlers for various sizes. To counter the problem of human observation error, digitalized dial gauges are used for easy observation of values. The idlers are rotated by means of high torque DC geared motor to take reading at 12,3,6,9’O clock respectively. The output values are being fed to the computer system by means of usb to overcome manual observation of values. We can observe that difficulties faced in manual run out testing are overcome and the testing process becomes easier.

Performance of electric motor is tied to torque which is the amount of turning power. This factor overcomes inertia and sustains acceleration during driving operation for vehicle's long distance travels. High torque motors have the advantage of fast response for performance. Electric propelled vehicles have been accomplished used performance magnet technology which has completely replaced and also reduced the large space usually occupied by combustion engine in motor-bike. This paper presents the improved design (FSM) structure of three-phase 24S-14P flux switching motor with permanent magnet flux source for optimum torque. The initial design structure generated torque of 241Nm which is considered low in maintaining fast torque response driving operation. High torque motor is factor for fast torque response operation. The 2D-finite element analysis by JMAG Designer version 14 is utilized in examining motor's performance in terms of torque and initial torque output has been improved to 348.6Nm, an increase of 107.6Nm. This performance shows and validates permanent magnet FSM with segmented rotor as a viable candidate for optimum torque capable of sustaining acceleration for long driving operation.

Because of the inherent risks, costs, and technical complexities, Deepwater development often requires customized solutions that employ life-of-well systems to enhance safety and boost field economics. All aspects of Deepwater well construction, including rig design, riser installation, pipe handling, and connection makeup and integrity must be implemented with a level of precision and service quality that enables the wells to produce safely for 30 or more years. For a multi-well Deepwater project in Southeast Asia, a major Operator engineered a tension-leg platform (TLP) with 24 slots for prospective development wells. The vertically moored floating platform moved laterally with changing weather and ocean conditions, and it was especially suited for the 1,640-ft (500-m) water depth in the project. TLPs typically use a top-tension riser (TTR) run between the platform and seabed. The riser was securely connected to the wellhead with an external tieback connector, and it remains in place for the life of the well. For this project, the Operator deployed a specially designed TTR that could be used for both drilling and production for the first time in the Eastern Hemisphere. Unlike conventional systems that use separate risers for drilling and production, the single-casing combination (SCC) TTR used the same outer riser for drilling, completion, production, and workover operations. This approach enabled the Operator to eliminate the time and cost of installing multiple sets of risers, and it streamlined the process of drilling the wells. The Operator's unique SCC-TTR design also enabled batch installation of TTR strings, resulting in improved operational efficiency & significant time savings. For a first-of-its-kind installation in Asia, the vendor engineered a fit-for-purpose tubular handling and makeup package for the SCC-TTR. The integrated, customized solution which was designed for use on the TLP combined several tubular running technologies and tools specially designed to handle non-API pipe sizes. As a whole, the package was able to handle the TTR joints, monitor and evaluate torque data for well integrity, and efficiently makeup the high-delta torque connections required for each well— all with the least possible disruption to the existing rig equipment. The customized, purpose-built tubular running equipment enabled completing the initial riser installation on the TLP in 98.5 hours. The second riser installation was completed in 81.5 hours. The remaining nine installations were batch installed in two phases with an initial target of 43 hours per installation. By implementing lessons learned and optimization of equipment, the remaining installations were completed nearly thirty-seven hours ahead of scheduled time, which resulted in a savings of US$500,000 for the Operator. This paper discusses (1) engaging with the Operator and rig contractor on requirements and limitations as well as collaboration between the global and regional teams to meet the customer's timeline and requirements while overcoming limitations of the rig, (2) meeting the challenges with customized, engineered solutions that satisfy industrial standards, (3) pre-qualifying the systems for penetration and torque, (4) providing a complete commissioning solution to prepare against uncertainties, and (5) focusing on cost and time savings to increase efficiency in a challenging market.

An operation of Progressing Cavity Pumps (PCPs) was challenged by a number of factors at the mature field. Taking into account a huge number of PCP wells, the scale of the problem was getting serious and financially sensitive. To investigate operational challenges from various perspectives, the customer invited most recognized PCP service authorities to conduct Root Cause Failure Analysis (RCFA) under complex wells Audit Program. This paper discusses the whole process, including initial well screening and ends up with final recommendations. Information provided in this paper could be considered as a practical, already implemented process to resolve PCP operational issues. It discusses the majority of PCP Specific applications and comes with possible solutions and outputs of such decisions.

This manuscript reveals both the full experimental and methodical details of a most-recent patent that demonstrates a much-desired goal of rotational maneuvers via angular exchange momentum, namely extremely high torque without mathematical singularity and accompanying loss of attitude control while the angular momentum trajectory resides in the mathematical singularity. The paper briefly reviews the most recent literature, and then gives theoretical development for implementing the new control methods described in the patent to compute a non-singular steering command to the angular momentum actuators. The theoretical developments are followed by computer simulations used to verify the theoretical computation methodology, and then laboratory experiments are used for validation on a free-floating hardware simulator. A typical 3/4 CMG array skewed at 54.73° yields 0.15H. Utilizing the proposed singularity penetration techniques, 3H momentum is achieved about yaw, 2H about roll, and 1H about pitch representing performance increases of 1900%, 1233%, and 566% respectfully.

This paper describes the design and analysis of electrical machine for robotic in-service inspection vehicle operating under harsh environmental conditions of nuclear reactor. Key requirements of high torque density and tolerance to high ambient temperature leads to selection of surface mounted permanent magnet motors for this application. Design criteria and details are presented. A coupled electromagnetic- thermal analysis is carried out with the help of analytical tool MOTORCAD-EMAG &THERM. Performance of three different motor configurations having slot/pole of 12/8, 12/10 and 24/16 are investigated. Based on performance comparisons,12/10 configuration is recommended for this application.

Objectives The paucity of safety information on intrauterine devices (IUD) for magnetic resonance imaging (MRI) examinations is clinically relevant. The aim of this study is to evaluate the MRI safety of clinically used IUDs composed of copper/gold and stainless steel at 1.5T and 3.0T. Materials and methods We assessed and compared the displacement force, torque effects, presence of imaging artifacts and heating of IUDs composed of copper/gold (western IUDs) and stainless steel (China) on 1.5 and 3.0T MRI systems. Results Gold/Copper IUDs can show small deflection angles of 7° ± 7° in the worst-case field gradient of 40T/m (equivalent to magnetic force of 0.5 mN), while the stainless steel IUD experienced significant magnetic force and deflection (Force > 7.5 N; deflection angle 90° ± 1°). Manual rotation and suspension method show no torque effects on gold/copper IUDs but high torque effects were observed by manual rotation on the stainless steel IUD. Heating measurements showed a temperature increase (rescaled to a wbSAR of 4 W/kg) of 1.4°C at 1.5T / 3.4°C at 3.0 T (stainless steel IUD), 3.2°C at 1.5 T / 3.8°C at 3 T (copper/gold IUD), 3.3°C at 1.5 T / 4.8°C at 3 T (copper 1), 3.8°C at 1.5 T / 4.8°C at 3 T (copper 2). The visible imaging artifacts of the copper and gold IUDs at 3 T MRI reach a diameter of 4 mm ± 1 mm, while the stainless steel IUD resulted in artifacts measuring 200mm ± 10 mm when using gradient echo pulse sequences. Conclusions Standard IUDs (copper/gold) can be considered as conditional for MR safety at 1.5 T and 3.0 T, demonstrating at wbSAR up to 4W/kg and a magnetic field gradient of up to 40T/m with minimal imaging artifacts. The stainless steel IUD, however, induces unacceptable artifacts and is potentially harmful to patients during MRI due to high magnetic dislocation forces and torque (MR unsafe)., PLoS ONE, 13 (10), ISSN:1932-6203

Despite of some drawbacks (interference, small contact ratio) internal gears with small difference in numbers of teeth have some advantages, especially when they are used in hypocycloid mechanisms (high transmission ratio and high torque at small size). This paper is focusing on using these kinds of gears in mechanisms that are using the benefits of them. Some mechanisms converting rotary motion into translation and hypocycloid mechanisms will be discussed.

A vane Magnetorheological (MR) damper for the purpose of suspension system was designed, manufactured and tested. The working methodology of the designed rotary damper was outlined and its theoretical model was also defined in the article. The magnetic field working as well as design was modelled on ANSYS. It is clearly defined in the results that damping ability of the designed damper is more than enough to be used for automotive suspension system. The manufactured damper was tested on MTS 858 table top system and performance of damper was analyzed at different currents and frequencies. Extra ordinary results proved that proposed vane type MR damper has high torque density and compact structure.

In a recent paper, the authors have introduced the concept of a novel bearingless (slice) motor topology, the bearingless permanent magnet Vernier motor intended for low speed and high torque applications. It features an exterior rotor typical for direct drives. The feasibility of this new motor topology was proven by finite element simulations. Based on the results of these simulations, a prototype was manufactured and successfully put into operation. This paper, therefore, presents the control scheme that comprises the measurement of active and passive forces, including the active torque generation, as well as the performance of this bearingless permanent magnet Vernier motor prototype.

Flux switching machine (FSMs) with several advantages of robust rotor structure, high reliability, high efficiency and high torque density have been develop in recent years. Among several types of FSM, HEFSM gives extra advantage at variable flux capabilities suitable for higher load conditions. However, the developed C-Type has a problem of separated stator core which lead to difficulty in manufacturing design as well as flux leakage to the outer stator. In order to solve the problem, iron flux bridges have been introduced to the stator core. Because of that, the separated stator core becomes the single piece of core. In this paper, various topologies of iron flux bridges is introduced and overviewed. Performances of torque at various flux bridge is analyzed and compared. This analysis is verified by Finite Element Analysis (2D-FEA).

Permanent magnet brushless dc (BLDC) machines are widely used due to various advantages such as high efficiency and high torque density, and therefore compactness as well as long expected lifetime. All of these benefits are of major interest when designing a drive for a small fan application of a few watts. This paper presents the design investigations of a small single-phase BLDC motor for such an application. Notably, it discusses different constraints which arise during the design process and which may be of special relevance due to the particular given power level and application.

Introduction: The ideal insertion torque values for placing dental implants to be immediately loaded is unknown, therefore it may be useful to evaluate the effect of insertion torque values on immediately loaded dental implants. Objectives: was to evaluate clinically and radiographically the placement of immediately loaded single implants inserted with high insertion torque (> 70 N.cm). Materials and Methods: This study was conducted on twelve patients divided in to two groups (study group and control group) with missed mandibular posterior teeth, Zimmer Swissplus Implants were inserted using Aseptico motor implant system, insertion torque was measured digitally. In the control group implants were inserted with medium torque (25-35 N.cm) while in the study group implants were inserted with high torque (>70 N.cm). Results: There was a statistically significant increase in bone density around the implants in the study group at 6 months postoperative compared with the control group. Conclusions: the use of high insertion torque (up to 70 N.cm) neither prevented osseointegration nor increased marginal bone resorption around tapered multithreaded dental implants placed in posterior mandible. Also there is statistically significant correlation between insertion torque and bone density around implants placed in posterior mandible.

In recent years, there is a growing interest for synchronous reluctance machines. This is due to their high torque density, flux-weakening operation capability, and high fault-tolerance capability. This paper deals with the analysis of a synchronous reluctance machine when eccentricity occurs. Both static and dynamic eccentricity are considered. An analytical model to predict the machine performance is described. As an example, a four-pole reluctance machine is analyzed, considering single, as well as multi flux-barriers per pole. The finite-element analysis confirms the results achieved by means of the proposed analytical model.

영구자석 동기전동기가 전압과 전류 제한을 갖는 상태에서 고속으로 운전하기 위해서는 약 자속 제어를 수행해야 한다. 영구자석 동기전동기는 설계 방법에 따라서 정 토크 및 약 자속 영역에서의 출력 특성이 상이하게 된다. 본 논문에서는 약 자속 영역에서의 고 토크를 위한 IPMSM의 회전자 형상 설계를 수행하였다. 우선 마그네틱 토크와 릴럭턴스 토크의 관계에 따라서 약 자속 영역의 토크 향상을 위한 방법을 제안한다. 제안한 방법을 IPMSM의 회전자의 형상 설계를 통해 적용하였고, 유한요소 해석을 통해 기존 모델과 개선 모델의 특성을 비교 분석하여 제안한 방법의 타당성을 검증하였다.Key Words : PMSM, Blower, Barrier, Shape design, Flux weakening†Corresponding Author : Dept. of Electrical Engineering, Hanyang Univerity, Korea.E-mail:julee@hanyang.ac.kr* Dept. of Electrical Engineering, Hanyang Univerity, Korea.Received : February 12, 2015; Accepted : March 29, 2015그림 1 증가 토크 부하의 한 예와 전동기 설계 포인트Fig. 1 One example of the increasing torque load and motor design point 1. 서 론 최근 건물과 철도분야의 공조 시스템은 에너지 절감을 위해서 많은 연구가 진행되고 있으며, 고효율화를 위해 기존 유도전동기인 블로워 모터를 속도 가변이 가능한 영구자석 전동기로 대체되고 있는 추세이다[1-2]. 영구자석 동기전동기의 장점을 간단히 살펴보면 유도전동기와 같이 브러시레스(brushless) 구조이며, 에너지밀도가 높은 영구자석을 사용하기 때문에 소형 제작이 가능하다. 영구자석에 의한 높은 공극자속밀도로 저속 고 토크의 출력특성을 가지며, 유도전동기와 달리 회전자에서 큰 손실이 발생하지 않아 유도 전동기보다 정격에서 약 2%정도 효율이 높다[3-4].영구자석 동기전동기의 성능 향상을 위한 형상 설계에 관한 많은 연구가 수행되어 왔다. 특히 고 효율을 위한 손실 저감[3], 정 토크 영역의 토크 밀도 향상[4], 토크 리플 및 코깅 토크 저감[5] 등이 수행되었다. 하지만 증가 토크의 경우 약 자속 영역에서 고 토크가 필요하나 이에 대한 연구는 거의 없는 실정이다.본 논문에서는 약 자속 영역에서의 고 토크를 위해서 영구자석 동기전동기의 회전자 형상 설계를 전자장 유한요소 해석 기반으로 수행하였다. 마그네틱 토크와 릴럭턴스 토크의 조합에 따른 약 자속 영역에서의 특성을 분석하고 비대칭 배리어 형상 설계를 통해 약 자속 영역에서의 고 토크를 위한 설계를 수행하였다.

During the period of children's development there are morphological, motor, physiological and psychological transformations, which may alter posture and natural forms of the human body on a temporary or permanent way. Many studies and systematic reviews indicate that there are a growing number of school children with impaired body state. Studies indicate the fact that many sports which include a lot of high torque and asymmetrical muscle involvements, are a precondition for the asymmetry of the spinal column. Also, some research has shown that girls are more susceptible to deviation of the spinal column than boys. The goal of this study was to detect the postural status female volleyball players of V.C. 'Eaton Srem Tempo' from Sremska Mitrovica. Subjects were 72 female volleyball players aged 12 to 16 years. The methods that are used to detect possible postural disorder are both clinical and plantography method whose results were interpreted with Thomsen's method. According to the results of the studies, it was concluded that there is improper posture status of a 68% female volleyball players (clinical method), while the irregular status of the foot has 58% of female volleyball players (plantography method). The most common physical irregularities were observed: knee joint hyperextension (34.72%), followed by unequal Lorenz's triangles or triangles stature (26.39%), and abnormal position of the shoulder (25% of subjects). We performed a correlational analysis between the values of body mass index and the drooping of the left and right foot index. The obtained values of correlation coefficients were 0.055 for the left and 0.083 for the right foot. Due to the nature of the results, the implementation of preventive and corrective measures is essential. Certain sports can be very effective for that, and there are discussions of various authors that it can be volleyball. Their application should be adapted to gender, age, physical status, current physical and functional condition of the individual, and aim to be achieved.

BD Field is the first development project of Husky-CNOOC Madura Limited (HCML) in Madura Strait, Indonesia which has a pressure of 8,100 psi and a temperature of 300°F. This Kujung gas reservoir contains of 5.5% CO2 and 5,000 ppm H2S, indicating that the reservoir is near High Pressure High Temperature (HPHT) and critical sour environment. This paper describes the best practices, lessons learned and strategy to control drilling issues such as slim hole, horizontal, near High Pressure-High Temperature, high density, and sour/acid gas environment to achieve the well TD with torque and ECD limitation, without compromising production target. Kujung reservoir section was drilled with an overbalance mud system as per CNOOC HPHT and sour well requirement. Drill-In fluid (DIF) system treated with potassium formate and manganese tetraoxide as weighting agents was chosen for drilling the 5-7/8-in. reservoir section. Throughout the drilling operation, higher torque and ECD value was identified compared with Torque and Drag (T&D) Calculation and Hydraulics simulation. This can lead to shallower TD decision, which has consequence of possibility not achieving initial target depth/production. Calibrating T&D model using the pickup/rotate/slack-off value from actual measurements on both cased and open holes was done in order to match the model with actual condition. Several analysis and review of all possible causes was performed, including performance of solids control equipment, inadequate hole cleaning, dog leg severity, wellbore direction and/or formation lithology changes. T&D and hydraulics simulation was also performed to foresee the possible operation limitation with several lateral lengths to ensure having successful drilling operation without compromising both operational safety and future well production. Based on the original model, with friction factor values of 0.25 (cased hole) and 0.35 (open hole), 1000-1500 ft lateral length of 5-7/8-in. slim hole section can be achieved. However, with calibrated T&D model, friction factor values were almost double the original model. Comprehensive planning was done to accomplish the drilling objectives, such as re-plan well trajectory to reduce dog leg severity, selection of drill fluid lubricant additives to ensure its stability at pH > 11 environment as planned to control sour gas and compatibility with other products, maximize centrifuge usage to minimize excessive LGS build-up caused by successive and repetitive mud system re-use for batch drilling operations, and diluted system using rehabilitation mud. Reduced friction factors and decreased torque values were the key parameters to successful drilling through the updated planned horizontal length. In terms of gas well production, the objective of well productivity was achieved during unloading operation when gas production result from the wells yielded higher Absolute Open Flow (AOF) as compared to the planned target. Hence a successful BD wells had been delivered to production.

Space robots require compact joint drive systems (JDSs), typically comprising of actuator, transmission, joint elements that can deliver high torques through stiff mechanical ports. Today's conventional space drive systems are made from off-the-shelf actuators and multistage transmissions that generally involve three to six stages. This current practice has certain benefits such as short development time due to the availability of mechanical components. However, it lacks a system-level integration that accounts for the actuator structure, size and output force, transmission structure, gear-ratio, and strength, and often leads to long and bulky assemblies with large number of parts. This paper presents a new robotic hardware that integrates the robot's JDS into one compact device that is optimized for its size and maximum torque density. This is done by designing the robotic joint using a special transmission which, when numerically optimized, can produce unlimited gear-ratios using only two stages. The design is computerized to obtain all the solutions that satisfy its kinematic relationships within a given actuator diameter. Compared to existing robotic actuators, the proposed design could lead to shorter assemblies with significantly lower number of parts for the same output torque. The theoretical results demonstrates the potential of an example device, for which a proof-of-concept plastic mockup was fabricated, that could deliver more than 200 N·m of torque in a package as small as a human elbow joint. The proposed technology could have strong technological implications in other industries such as powered prosthetics and rehabilitation equipment.