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Rescue robots, which are robots that have been designed for the purpose of rescuing people, are useful in natural and man-made disasters. In this paper, we develop a remote controlled rescue robot using ZigBee communication. The main body of the rescue robot is a caterpillar with two arm crawlers. Two arm crawlers are used for running over obstacles. Users can control the rescue robot forward/backward and right/left with a remote controller through ZigBee communication. Also it is possible to observe the situation of a disaster area by a Wi-Fi camera on PC. The Wi-Fi camera is rotated right/left with the remote controller. The effective distance between the rescue robot and the remote controller is 120 m outdoors.

In this paper, we present a dual lock system using radio-frequency identification (RFID) and fingerprint recognition. It is a secure and reliable locking system which can be implemented in home, offices, school and in any kind of organization. Even if the users lost the RFID card, they can unlatch the lock with their fingerprints. Only the registered users are able to access using their fingerprints and the RFID tags. If any unauthorized persons try to have an access, first of all short message service (SMS) will send a text message to an owner using global system for mobile communications (GSM), and at the same time a TTL camera will take a snap of that person and store it in a SD card for reference of the owner. The core of the system is the Arduino Mega 2560 which is interfaced with a fingerprint scanner module, a RFID card reader module, the TTL camera, an SD card module, a GSM shield, a liquid crystal display (LCD) and an electric door strike.

With the rapid development of the power system, the fault current becomes a big problem. The current limiting measures become more and more important. The saturated-core fault current limiter(SFCL) is one of the promising methods [1]. The most serious fault in electric power system is three-phase short-circuit fault, and the fault current is more likely to exceed the circuit breaker's capacity. The use of three single-phase current limiters at the same time will need a lot of ferromagnetic material and space. A compact three-phase SFCL was proposed in [2], but it cannot limit three-phase fault current [2]. So we propose a novel structure of Economical Three-phase Saturated-core Fault Current limiter(ETSFCL). The novel structure has good clipping performance at three-phase fault conditions. Compared to three single-phase SFCLs proposed in [3], it saves a lot of ferromagnetic material and reduces the AC flux through the permanent magnet. The stability of the permanent magnet is greatly improved and the risk of demagnetization is reduced. In this paper, the operating principle of the proposed structure is explained by analyzing its equivalent magnetic circuit and electrical circuit. FEA models were established in ANSOFT to verify the its effectiveness.

In order to protect high voltage direct current(HVDC) system from destructive damage caused by large DC fault current, a HVDC system saturable core type fault current limiter(DCSFCL) is proposed previously. However, through principle investigation and simulation analysis of DCSFCL, coil inductance of DCSFCL do not have a large changing rate (CR) when a fault occurs, so clipping performance of it will not be quite satisfying. In order to increase CR and improve clipping performance of original DCSFCL, further improvements need to be carried out. In this digest, a modified three limb structure of DCSFCL(TSFCL) is proposed and equivalent magnetic and electric circuit are analyzed. Simulations carried out on ANSYS shows that clipping performance is improved by a large scale.

The start current can reach up to as high as 4–7 times of the motor's rated current when high voltage motors start directly. For super large capacity motors (voltage above 6 kV, power above 10000 kW), the direct start current could reach 5000 Ampere or more [1]. Such large start current will not only have a huge impact on the motor itself but also cause a sudden decline of the grid voltage [2], [3]. In order to resolve this issue, a novel coupled auto-transformer and magnetic control (CATMC) soft starter method was proposed in this paper. The new structure of CATMC soft starter combines the two functions of the auto-transformer and the magnetic control reactor (MCR) through ingenious electric and magnetic circuit design. Hence the start current is reduced in two ways and the structure becomes more compact and flexible.

For future high voltage direct current (HVDC) grids, the dc protection system is often considered as one of th e main challenges due to the difficulty in interrupting a large dc current and the stringent time constraint imposed by the fast rising fault current[']. Therefore, a novel DC system fault current limiter based on saturable core reactor theory (DCSFCL) was proposed previously. In order to obtain better performance of DCSFCL that is unable to be accomplished by single magnetic material, mixed magnetic materials were applied to take advantages of different magnetic materials. Furthermore, magnetic valves were also added to original DCSFCL topology, which is a good way to optimize clipping performance and reduce the usage of both magnetic materials and permanent magnets (PM). ANSYS models were built and finite element analysis were carried out to verify the feasibility of these deductions.

Grain-oriented (GO) materials are widely used in the iron cores of power transformers and reactors, as they provide a high permeable path within low iron losses. However, magnetic properties of GO materials exhibit strong anisotropy, and this intensifies the flux concentration inside the iron core. Furthermore, in a three-phase transformer, rotational magnetic field is generated at the T-joint part. Therefore, the magnetic flux path is not parallel to the rolling direction of the steel plate in the T-joint area, thus results in higher iron loss at the T-joint area. To overcome the foregoing problems, we proposed two kinds of hybrid iron core models applying different grades of silicon steel plates and their effectiveness is investigated by using magnetic field analysis and iron loss analysis with finite element method.

To reduce the iron loss of a three-phase reactor composed of Grain-oriented silicon steel plates, we proposed two reactor models: applying oblique joints between the legs and yokes, and applying isotropic brick iron cores at the L and T shaped joints. The effectiveness of the proposed models are investigated through magnetic field and iron loss analyses considering the anisotropic magnetic characteristics. It is found that the iron loss of the proposed model with isotropic butt joints can be about 12 % reduced compared with the ordinary one.

Due to the increasing demands for electric energy and installation of distributed generation, the rising fault current poses a great threat to those existing power system components.

The saturable magnetically controlled reactor (MCR) applying dc control currents has been widely used in the voltage regulation and reactive power compensation in the electric power system [1].

In this paper, the play model and the free energy model are applied to represent the hysteretic properties of non-oriented steel plates and compared. The ac symmetric B-H loops and PWM minor loops are represented by both methods and the results are compared with the measured ones. Small minor loops representation is found not complete with both methods. However, in play model, it can be easily improved by increasing the number of hysterons. In the spring model, the way to improve the minor loop representation accuracy is under discussion, whereas its identification is simpler than play model as less parameters are required.

The Multi-magnetic-valve structure is adopted in Magnetic Controlled Reactors (MCR) to reduce their current harmonics. However, the reactance can't be precisely calculated for its complicated structure. In this paper, an improved method to calculate its inductance is presented and the simulation analysis based on finite element method (FEM) verified its validity. The analysis results demonstrate that the length and the number of magnetic valves have a great impact on the inductance of MCR.

Due to the leakage flux effect, the nonuniform magnetic flux distribution would weaken the biasing ability of PMs in a permanent-magnet-biased fault current limiter. To improve the biasing ability of PMs and reduce the cost, a novel small-section permanent-magnet-biased fault current limiter is proposed by this paper. Firstly, the principle and the optimal small-section structure are introduced. To validate the impact of small section on the biasing ability of PMs, various FEA simulation and optimization study are performed in Ansoft. The simulation and optimization results verify that the small section can improve the biasing ability of PMs and reduce the cost.

Eddy current loss of NdFeB permanent magnets (PMs) are widely analyzed in permanent magnet motors. And it's necessary to analyze this issue in saturated core fault current limiter (SCFCL). This digest discusses the coupled 2-D finite element analysis (FEA) of the SCFCL and 3-D analytical model of PMs to evaluate the eddy current loss of PMs in a SCFCL. The comparison between result from coupled method and that from 3-D FEA verifies the applicability of the coupled method in analyzing eddy current loss of PMs in SCFCL.

In allusion to the difficulties in the optimal gear capacity design of the superconducting controllable reactor (SCR), a novel design optimization method of SCR is proposed in this paper combining field-circuit coupling finite element method (FEM) and Immune Algorithm (IA). Field-circuit coupling finite element method is realized in ANSYS and immune algorithm is embedded in ANSYS by ANSYS Parameter Design Language (APDL). The proposed method and the conventional method will make a detailed comparison. Finally, a 380V/30 KVar SCR prototype is fabricated, and detailed experiments are done.

To reduce the size and requirement of DC biasing capacity of saturated-core fault current limiter, a novel hybrid compact saturated-core fault current limiter (HCFCL) is proposed by this paper. The three-limb structure with Permanent magnets can reduce the size and DC biasing capacity. Firstly, the principle of HCFCL is introduced. To validate the performance, various FEA simulations with the 3D nonlinear field-circuit coupling transient analysis are carried out in Ansoft. And a 220V/10A prototype of HCFCL is designed and tested. The simulation and experimental results verify the effectiveness and excellent performance of proposed structure.

In the ordinary saturable magnetically controlled reactors inserted in the legs with magnetic valves of smaller cross-sectional areas (VMCR), the flux concentrates in the legs due to the valves so the iron loss and noise are increased. In this paper, to reduce the iron loss and noise of VMCR, the structure of the valves is improved by using 3D nonlinear magnetostatic field analysis taking account of the laminated structure and the anisotropy of iron cores. It is shown that the iron losses can be reduced by about 30% improving the valve structure.

This paper proposes a model order reduction (MOR) technique based on the proper orthogonal decomposition method, to speed up nonlinear magnetostatic analysis of inverter-driven electrical machines. In this method, a set of solutions of the original problem is obtained at relatively large intervals, covering the whole cycle. The solutions, known as snapshots, are then used for the linearization as well as the order reduction of the matrices at the intervals. The reduced linearized matrices are then interpolated for time instance within the strides, supplemented with initial guess obtained by interpolating the snapshots. The method enormously reduces the number of matrix projections. Furthermore, it limits the number of the Newton-Raphson iteration to one. The results of applying the method on the magnetostatic analysis of interior permanent magnet motor shows that the method is several time faster than the conventional MOR with almost the same accuracy.

In this paper, a novel hybrid saturated-core fault current limiter (HSFCL) is proposed considering the reliability of permanent magnets (PMs). For the HSFCL, a hybrid PMs/DC coil is designed to saturate the core and a fault limiting reactor is used to guarantee the fault clipping performance. The method of electromagnetic coupling is used to analyze the HSFCL based on ANSYS Maxwell. Simulation results have demonstrated that the HSFCL is efficient in fault clipping and stability enhancement of PMs.

This digest proposed a model of superconducting controllable reactor and calculates its reactance based on finite element method. In order to ensure the safe operation of superconducting reactor, the digest devises a control system for superconducting windings based on S7-200 PLC after analyzing the DC component and overvoltage of superconducting winding and puts forward an optimal control strategy. A 380V/30kVar SCR was fabricated for experiments and the experimental results show the correctness of this method and the feasibility of the control device.

In this paper, a simple structure of L and T shaped butt joints composed of anisotropic and isotropic block cores is proposed. The iron loss of a three-phase reactor having the proposed joints is compared with that having ordinary joints composed of anisotropic block cores only. It is shown that the iron loss can be reduced by applying the proposed joints because the flux distribution becomes more uniform.

Excess loss evaluation in SiFe electrical steel sheets is important for accurate iron loss prediction of electrical machines, especially under high frequencies. In this paper, a numerical excess loss estimation method of SiFe sheets considering the domain wall bowing caused by pinning sites is proposed. An equivalent magnetic field representing the pinning effect is implemented into a general nonlinear eddy current finite element analysis. The hysteresis and eddy current losses are calculated using the flux and eddy current distributions obtained from the proposed analysis directly. The proposed method is applied to two different grades SiFe sheets first. The calculated iron losses under various frequencies in one sheet are compared with catalogue data and less than 2% deviation can be achieved.

To shield the leakage flux densities of 3 T magnetic resonance imaging (MRI) higher than 1.5 T MRI and to reduce the degradation of magnetic properties during construction, the design of an open-type magnetically shielded room (MSR) combined with square cylinders made of magnetic and conductive materials should be improved. This paper reports on an optimal design for magnetic cylinders to improve the shielding effect, while also considering ease of construction with a view to practical use. Firstly, the structure of the magnetic cylinders, such as their opening width and the slit width were optimized using a 3D linear magnetic-field analysis. Using optimal magnetic cylinders, when the relative permeability (μ_r) of the magnetic material is larger than 10 000, the reluctance of gaps between the cylinders is the main contributor to the leakage flux. So, the required (μ_r) of the magnetic material is 10 000 and oriented silicon steel is adopted instead of the non-oriented type. Secondly, as an optimal construction method, it was determined by experiment that oriented silicon steel sheets, annealed after bending, should be laminated so that the effect of gaps on butt joints between steel sheets on the magnetic property of the cylinder becomes smaller. This enables the relative permeability of 10 000 when the maximum flux density of the material in the cylinder is less than 1.7 T. Finally, the minimum thickness of oriented silicon steel sheet of cylinders depending on the distance from a 3 T MRI is obtained using linear magnetic analysis under the condition that the maximum flux density of the material of the cylinder is less than 1.7 T. In the case of the thickness of 3.8 mm, the leakage flux density of 3 T MRI is decreased to less than a guideline (0.5 mT) when the distance between the cylinders and the center of MRI is larger than 2 750 mm. This indicates that the optimal design and construction method of an open-type MSR for 3 T MRI composed of magnetic square cylinders are realized.

To improve the comfort of hospital patients, we have developed a new open-type magnetically shielded room (MSR) for magnetic resonance imaging (MRI), constructed by stacking square cylinders composed of magnetic material on the inside and a conductive material on the outside. The magnetic cylinder shields against leakage of the magnetic field from the MRI, while the conductive outer cylinder prevents intrusion of the electromagnetic field from outside by waveguide attenuation. First, the optimal design of the magnetic cylinder was determined, using 3-D magnetic field analysis with a simple cubic MSR. Second, the validity of the analysis and the practical realization of the designed MSR were investigated using a small experimental model. Finally, from a design perspective and the standpoint of saving space, the optimal combination of electromagnetically shielded glass and conductive cylinders made of aluminum was studied by measuring the electromagnetic shielding effect. As the optimal design of an open-type MSR for an MRI, we have adopted a combination of single-layered electromagnetically shielded glass together with stacked cylinders. These cylinders are made of a square cylinder, 144 x 144 mm and 300 mm long, made of silicon steel (thickness t =1 mm) and divided into three parts along the axial direction, placed inside a second square cylinder made of aluminum, 150 x 150 mm and 300 mm long (t = 3 mm). This MSR construction technique creates an open, spacious feeling inside the facility and can be easily fabricated at low cost.

Today, we are able to easily obtain data such as stock prices and market information through media such as the Internet. However, it is not so easy to come by useful information from this data. The reason for this is that there is a mix of many different kinds of information. Such a situation leads to difficulty in grasping trends in the data through just one rule, and so one must find a rule for each relevant factor. Therefore, the need for finding relevant factors is inevitable. For this reason, in our research we developed an algorithm that enables one to extract factors that have causal relationships with one another, and indicated its usefulness through experiments.

In order to investigate the magnetic property of material for scaled-down experiments on electric machines, numerical modeling on the power and loss densities of scaled-down laminated cores is studied in this paper. To reduce computational cost, the laminated core is modeled combining a 3D solid core analysis with a 1D steel plate analysis The hysteresis loss, eddy current loss, iron loss and power density of the laminated core are calculated using the electromagnetic field distribution result from the finite element analysis. The relationship between the increment of the power density and iron loss density versus the coil current density and frequency are investigated. The proposed method can be used to design and optimize the scaled-down electromagnetic devices with laminated cores.

Numerical modeling of iron loss considering the pinning and skin effect in silicon steel sheets is approached in this work. The pinning and skin effect are considered as the main factors of anomalous eddy current loss in silicon steel plates. The pinning is considered by implementing an initial flux distribution in the nonlinear eddy current finite element analysis, which includes the skin effect of flux. Thus the mutual coherence between pinning and skin effect can be achieved in the proposed numerical method. The hysteresis loss and eddy current loss are calculated using the obtained flux and eddy current distribution, while anomalous eddy current loss is spontaneously included in the calculation. The proposed method is applied to different grade non-oriented materials, and the calculated iron losses are compared with the measured data under various frequency.

To shield magnetic noise, magnetically shielded rooms (MSR) are used for biomagnetic measurements, etc. To evaluate the shielding factor SF (SF=B n / B s , B n and B s are the flux densities at the center of the room without and with MSR, respectively), the magnetic noise is applied by coils. However, SF depends on the size and position of the coils, so the standard of JEITA (Japan Electronics and Information Technology Industries Association) EM-4502, in which the shielding factor (SF o ) of MSR for the uniform magnetic field in the extremely low-frequency region of less than 1 Hz without eddy current effect is estimated using coils within 10% error [1-2], has been already published [3]. Currently, a standard method for the low-frequency region, e.g. 50 Hz, with eddy current effect is being discussed. In a previous work [4], it was shown that the coil should be placed in front of the door of MSR and a much larger estimation error than 10% should be permitted for practical use in the standard to estimate SF o for the low-frequency region.

To reduce the harmonics of a saturable magnetically controlled reactor (MCR), an improved MCR (VMCR) with magnetic valves saturated by opposite dc currents has been proposed and its performance is analyzed by an analytical method and verified by the measurement. In this paper, the mechanism of the harmonics suppression of VMCR is analyzed in more detail by the numeric magnetic field analysis considering the magnetic flux leakage and precise magnetic nonlinearity. For this purpose, the performances of MCR and VMCR are compared with each other. It is shown that the harmonics can be reduced by using VMCR controlling the saturation degrees of the magnetic valves.

In the magnetic field analysis with the voxel modelling, to reduce the error due to the rough shape approximation, the nonconforming mesh is introduced. The flux density and the force obtained from the voxel modelling with nonconforming mesh are compared with those obtained from the ordinary voxel modelling in a simple 2D model. It is shown that the nonconforming mesh is effective because the number of elements can be greatly reduced compared with that for the conforming mesh with the same accuracy.

To improve amenity for patients in hospitals, we have proposed an open-type magnetically shielded room (MSR) composed of magnetic and conductive cylinders for a magnetic resonance imaging (MRI). The design method of the opening part, that enables the leakage flux densities outside to be less than 0.5mT, is discussed taking account of magnetic saturation. First, the homogenization technique is applied to the design method of the opening part to reduce the number of elements for cylinders. Moreover, the magnetic characteristic of the opening part is assumed to be linear to obtain the ideal flux distribution. Next, the thickness of the magnetic cylinders is determined using the flux distribution in the real model reproduced from that in the homogeneous model so that the magnetic cylinders are not saturated. Finally, the design method is verified using the realized open-type MSR.

Advances in cMUT technology accelerated research efforts in the design of driver/receiver front-end integrated circuits (ICs) for transducer arrays. Considering ASIC manufacturing costs and turn-around times, a thorough assessment of the front-end circuit before tape-out is compulsory. For an accurate evaluation, circuit simulations have to be run on a system-level model that includes the post-layout extracted netlist of the IC and an equivalent circuit for the transducers pulse-echo behavior. In this paper, we present the modeling, design and test of a front-end IC for 2D cMUT arrays. To evaluate the circuit response, we first developed a pulse-echo model for an array element. The model is a modified version of the Mason Equivalent Circuit where the radiation impedance term has been replaced by an RLC network to include the effects of finite transducer size and diffraction loss. The model has been verified by running transient FEA simulations using ANSYS. Meanwhile, we designed a driver/receiver front-end circuit for a 2D cMUT array element. The circuit was composed of a high voltage (50 Volt) pulse driver, an NMOS protection switch and a trans-impedance amplifier. We then used the transducer model to simulate the response of the front-end circuit using Cadence Spectre. The simulation results are then verified by comparing them to experimental data obtained from the manufactured front-end IC. We demonstrated that information obtained from a model describing the behavior of the front-end circuit together with the transducer element is consistent with the experimental data and hence can be used to assess system performance.

The method for magneto-fluid analysis of an electromagnetic fluid pump taking account of eddy currents due to velocity effects is proposed. In both analyses, Lagrange coordinate system is applied in time differential terms. The proposed method is applied to a simplified electromagnetic pump model. It is shown that the eddy currents due to velocity effects should be considered

At the Japan Aerospace Exploration Agency, a zero magnetic field is required to test the magnetic characteristics of spacecrafts, satellites and to calibrate magnetometers. This zero-magnetic field is realized by means of a three-axis coil system which can cancel the uniform earth's magnetic field, but cannot cancel magnetic disturbance because of no magnetically shielded room. Therefore, the magnetic disturbance within and in the vicinity of the zero-magnetic field of a Spacecraft Magnetic Test Site (SMTS) is investigated by comparing the results of three-dimensional (3-D) finite-element analysis with measurements. Distributions of the magnetic disturbance due to three hemispherical objects-the roof, the foundation made of concrete, and the hole in the ground for the SMTS building-are analyzed and compared with those measured by a proton magnetometer. Consequently, it is shown that the hemispherical hole in the ground for the SMTS building, which has weak magnetism and is a little higher than that of concrete, generates a weak magnetic disturbance in the zero-magnetic field of the SMTS