Additional Shielding Research Articles

Neutronics analysis and assessment of shielding options of pipe forest and Bioshield-Plug design for ITER TBSs

In ITER [1], it is foreseen to have two Test Blanket Systems (TBS) installed in two dedicated Equatorial Ports (EP) for the purpose of testing and validating different concepts of tritium breeding blankets [2]. Each TBS consists of a Test Blanket Module Port Plug (TBM PP) and its associated systems; the Pipe Forest (PF) in the Port Interspace (PI) area and the corresponding systems in the Port Cell (PC) area. While analyses have been conducted before [3], the design has since gone through major evolution with a redesign of the PF, a new BP based on the butterfly doors concept, and an optional activated water delay tank. In this paper, the results of a comprehensive nuclear analyses that aim at assessing the neutronics performance of the revised PF and BP, will be discussed. These include calculations of neutron flux distributions and Shutdown Dose Rate (SDDR), following SA2 [4] scenario, in a baseline configuration and exploring the option of adding additional shielding plates in the PF. It has been found that the additional shielding plates reduces the neutron flux in the PI by ∼40–60% and the SDDR in the PI, due to activated components, by ∼50%.

Out-of-field doses from radiotherapy using photon beams: A comparative study for a pediatric renal treatment.

PurposeFirst, this experimental study aims at comparing out‐of‐field doses delivered by three radiotherapy techniques (3DCRT, VMAT (two different accelerators), and tomotherapy) for a pediatric renal treatment. Secondly, the accuracy of treatment planning systems (TPS) for out‐of‐field calculation is evaluated.MethodsEBT3 films were positioned in pediatric phantoms (5 and 10 yr old). They were irradiated according to four plans: 3DCRT (Clinac 2100CS, Varian), VMAT (Clinac 2100CS and Halcyon, Varian), and tomotherapy for a same target volume. 3D dose determination was performed with an in‐house Matlab tool using linear interpolation of film measurements. 1D and 3D comparisons were made between techniques. Finally, measurements were compared to the Eclipse (Varian) and Tomotherapy (Accuray) TPS calculations.ResultsAdvanced radiotherapy techniques (VMATs and tomotherapy) deliver higher out‐of‐field doses compared to 3DCRT due to increased beam‐on time triggered by intensity modulation. Differences increase with distance to target and reach a factor of 3 between VMAT and 3DCRT. Besides, tomotherapy delivers lower doses than VMAT: although tomotherapy beam‐on time is higher than in VMAT, the additional shielding of the Hi‐Art system reduces out‐of‐field doses. The latest generation Halcyon system proves to deliver lower peripheral doses than conventional accelerators. Regarding TPS calculation, tomotherapy proves to be suitable for out‐of‐field dose determination up to 30 cm from field edge whereas Eclipse (AAA and AXB) largely underestimates those doses.ConclusionThis study shows that the high dose conformation allowed by advanced radiotherapy is done at the cost of higher peripheral doses. In the context of treatment‐related risk estimation, the consequence of this increase might be significative. Modern systems require adapted head shielding and a particular attention has to be taken regarding on‐board imaging dose. Finally, TPS advanced dose calculation algorithms do not certify dose accuracy beyond field edges, and thus, those doses are not suitable for risk assessment.

Single Scans of Ti-6Al-4V by Directed Energy Deposition: A Cost and Time Effective Methodology to Assess the Proper Process Window

Directed energy deposition is an additive manufacturing technology which usually relies on prototype machines or hybrid systems, assembled with parts from different producers. Because of this lack of standardization, the optimization of the process parameters is often a mandatory step in order to develop an efficient building process. Although, this preliminary phase is usually expensive both in terms of time and cost. The single scan approach allows to drastically reduce deposition time and material usage, as in fact only a stripe per parameters combination is deposited. These specimens can then be investigated, for example in terms of geometrical features (e.g. growth, width) and microstructure to assess the most suitable process window. In this work, Ti-6Al-4V single scans, produced by means of directed energy deposition, corresponding to a total of 50 different parameters combinations, were analyzed, focusing on several geometrical features and relative parameters correlations. Moreover, considering the susceptibility of the material to oxygen pick-up, the necessity of an additional shielding gas system was also evaluated, by comparing the specimens obtained with and without using a supplementary argon flow. A process window, which varies according to the user needs, was found together with a relationship between microstructure and process parameters, in both shielding scenarios.Graphic

Shielding design and neutronics calculation of the GDT based fusion neutron source ALIANCE

This paper presents the high flux neutron shielding design and extensive neutronics calculations of GDT based fusion neutron source ALIANCE. Neutron distribution of ALIANCE is strongly inhomogeneous along the axis: significant portion of the neutron flux is generated near the two mirrors, while the rest of it is spread over the remaining central volume of plasma. The shielding design includes 40 cm stainless steel as the main shielding layer and an additional 5 cm tungsten carbide shielding layer at mirror plugs to protect superconducting coils from neutron damage and reduce nuclear heating. The simulations have been carried out by using Monte Carlo transport code SuperMC with nuclear data library FENDL 3.1. Results show that the nuclear heating on the mirror coils can be reduced by more than two thirds with additional tungsten carbide shield, and fast neutron fluence by 30 %. The highest nuclear heating and the highest fast neutron fluence zones are located at the mirror coils, and the values are about 300 W/m3 and 9 × 1018 n/cm2 respectively, which meets the threshold of ITER superconducting coils. The specific activities of shielding layers are of order of 1012 Bq/kg. The structural materials’ specific activities will decrease to 4 × 1011 Bq/kg in one year after shutdown, and their decay heat will quickly drop below 2 kW/m3 after one day. Besides, all the structural materials of ALIANCE can be recycled by different recycling technologies. The modeling and calculations reported in this paper will be beneficial for the pre-conceptual engineering design of ALIANCE.

State-of-the-art ultrasonic sensor designed to improve longwall production rates and operation safety

The article describes issues related to the development of a sensor measuring the distance from the end of the shield support canopy to the face of the longwall panel. The sensor's task is to detect rock falls because in such a case, empty spaces in the coal seam below the roof are generated. The sensor is a part of the system which task is to predict unfavourable behaviour of the longwall roof affecting the continuity of mining. Due to an untypical workplace and difficult conditions prevailing there, it was not possible to use a typical sensor. The ultrasonic technique was used for this purpose. The next research stages related to the development of the sensor were described. Tests of various types of ultrasonic transducers, working at different parameters, were described. Only transducers with a closed structure were considered because they can operate in the presence of high dustiness and humidity. The sensor casing was adapted to a specific type of shield support. The installation location should not be accidental, as an additional hinged shield is mounted at the end of the canopy, which is an obstacle in the measuring track and can even completely cover it, making measurements impossible. The sensor is mounted close to the side edge of the shield support canopy using small free space, enabling a measurement. Structural elements of the canopy are obstacles in the measuring track and are a source of interference of the received signals. The ultrasonic transducers are built-in tubes, which direct the ultrasonic wave and amplify the received signals. The results of laboratory tests of the model of the path measurement sensor are presented. They describe the impact of analysed aspects, i.e. the type of transducers used, the structure of the surface that the wave is reflected from and the mechanical solutions on the quality of received signals. A prototype of a sensor installed on shield support is presented.

Optimizing the detection, ablation, and ion extraction efficiency of a single-particle laser ablation mass spectrometer for application in environments with low aerosol particle concentrations

Abstract. The aim of this study is to show how a newly developed aerodynamic lens system (ALS), a delayed ion extraction (DIE), and better electric shielding improve the efficiency of the Aircraft-based Laser ABlation Aerosol MAss spectrometer (ALABAMA). These improvements are applicable to single-particle laser ablation mass spectrometers in general. To characterize the modifications, extensive size-resolved measurements with spherical polystyrene latex particles (PSL; 150–6000 nm) and cubic sodium chloride particles (NaCl; 400–1700 nm) were performed. Measurements at a fixed ALS position show an improved detectable particle size range of the new ALS compared to the previously used Liu-type ALS, especially for supermicron particles. At a lens pressure of 2.4 hPa, the new ALS achieves a PSL particle size range from 230 to 3240 nm with 50 % detection efficiency and between 350 and 2000 nm with 95 % detection efficiency. The particle beam divergence was determined by measuring the detection efficiency at variable ALS positions along the laser cross sections and found to be minimal for PSL at about 800 nm. Compared to measurements by single-particle mass spectrometry (SPMS) instruments using Liu-type ALSs, the minimum particle beam divergence is shifted towards larger particle sizes. However, there are no disadvantages compared to the Liu-type lenses for particle sizes down to 200 nm. Improvements achieved by using the DIE and an additional electric shielding could be evaluated by size-resolved measurements of the hit rate, which is the ratio of laser pulses yielding a detectable amount of ions to the total number of emitted laser pulses. In particular, the hit rate for multiply charged particles smaller than 500 nm is significantly improved by preventing an undesired deflection of these particles in the ion extraction field. Moreover, it was found that by using the DIE the ion yield of the ablation, ionization, and ion extraction process could be increased, resulting in up to 7 times higher signal intensities of the cation spectra. The enhanced ion yield results in a larger effective width of the ablation laser beam, which in turn leads to a hit rate of almost 100 % for PSL particles in the size range from 350 to 2000 nm. Regarding cubic NaCl particles the modifications of the ALABAMA result in an up to 2 times increased detection efficiency and an up to 5 times increased hit rate. The need for such instrument modifications arises in particular for measurements of particles that are present in low number concentrations such as ice-nucleating particles (INPs) in general, but also aerosol particles at high altitudes or in pristine environments. Especially for these low particle number concentrations, improved efficiencies help to overcome the statistical limitations of single-particle mass spectrometer measurements. As an example, laboratory INP measurements carried out in this study show that the application of the DIE alone increases the number of INP mass spectra per time unit by a factor of 2 to 3 for the sampled substances. Overall, the combination of instrument modifications presented here resulted in an increased measurement efficiency of the ALABAMA for different particle types and particles shape as well as for highly charged particles.

New insights into prediction of weak \u03c0\u2013\u03c0 complex association through proton-nuclear magnetic resonance analysis

For analysis of weak π–π complexes proton-nuclear magnetic resonance (proton-NMR) simultaneously provides information of stacking configurations and association constants left( K right) However, an apparent issue for this approach is inconsistent/impossible constant estimation which often leads to unreasonable interpretation for π–π complexation. Whether or not this proton-dependent constant variation could be attributed to simple experimental uncertainties or to more sophisticated additional unspecific shielding effects (AUS effects) was addressed by means of hypothesis tests using a robust bootstrap technique in this report. Our analysis shows the significance of AUS effects on such variation in constant estimation. A following study using numeric simulation further reveals the variation patterns induced by AUS effects and concludes that the largest K among the obtained K estimates of a complex is considered as the best estimate of K due to minimum deviation from the true value of K and the multiple K estimates of a π–π complex could provide preferable inferences for complex geometries.

Zn2+ Ions-Immune Virucidal activities for children and adults with preventions against 2019-nCoV and COVID-19 infection

Zinc induced pediatric preventing respiratory 2019-nCoV is required that supplementation with zinc gluconate 20 mg in Zn deficient children resulted in a nearly twofold reduction of acute lower respiratory infections as well as the time to recovery. Zinc supplementation in children is associated with a reduction in the incidence and prevalence of pneumonia. Preventing 2019-nCoV pneumonia is required that zinc supplementation alone (10 to 20 mg) for more than 3 months significantly reduces in the rate of pneumonia. zinc pediatric intake may be required to be effective range 10～20 mg/d for 2019-CoV prevention, 10～30 mg/d for reduction of COVID-19 bronchitis, and 20～30 mg/d for recovery from COVID-19 pneumonia, in which Zn2+ could bind with viral surface proteins by Zn2+ions-centered tetrahedrally coordination pattern. On the other hand, for aults, the zinc-homeostatic immune concentration may provide a protective role against the COVID-19 pandemic, likely by improving the host’s resistance against viral infection. 50 mg of zinc per day might provide an additional shield against the COVID-19 pandemic, possibly by increasing the host resistance to viral infection to minimize the burden of the disease. In order to prevent that an outbreak of respiratory sickness caused by a novel coronavirus (COVID-19) has become a serious public threat and disrupted many lives,assessing the efficacy of FDA-approved Zn-ejector drugs such as disulfiram combined with interferon to treat COVID-19 infected patients has been proposed. The key strategies for preventing lung damages include avoiding direct lung infection, altering host-virus interactions, promoting immune responses, diluting virus concentrations in lung tissues by promoting viral migration to the rest of the body, maintaining waste removal balance, protecting heart function and renal function, avoiding other infections, reducing allergic reactions and anti-inflammatory. The interactions had been found on the binding specificity by Zn2+ ions-centered tetrahedral geometric coordination of the inhibitors against 3C and 3C-like proteases. In addition, transient zinc chelation TPEN and EPDTC have been noted as preventing virus replication. Zinc-induced ROS production in COVID-19 respiratory ailment and pneumonia occurs both in children and adults. In children. ROS production in zinc (Ⅱ)-immune pediatric patient with COVID-19 bronchitis and pneumonia cannot be elucidated yet. In adults, zinc induced ROS generation in pulmonary COVID-19 infected cells is that alterations of ROS-producing and scavenging pathways that are caused by respiratory viral infections are implicated in inflammation, lung epithelial disruption, and tissue damage, and, in some cases, even pulmonary fibrosis. The involvement of oxidative stress in cell deaths caused during RNA virus infection and ROS production is correlated with host cell death.

Flexible triboelectric 3D touch pad with unit subdivision structure for effective XY positioning and pressure sensing

Abstract Touch pad is an important human-machine interface in many information exchange scenarios. The rapid develop of portable or wearable devices and internet of things calls for a self-powered, thin, flexible, efficient and secure tactile mapping solution. Here, we present a triboelectric 3D touch pad with the above advantages. It consists of a multi-channel positioning layer and a single-channel pressure sensing layer both based on the rational design of triboelectric nanogenerator. Specially, the positioning layer is developed as a XY Complementary Subdivision Pattern (XYCSP) to reduce the number of channels as well as the XY crosstalk. With this particular pattern, the near end crosstalk is suppressed to a value of 0.16 without additional shielding. Moreover, it can effectively respond to a contactor with big or small size by regulating successive subdivision of a positioning unit. Based on this optimal design, a trajectory imaging pad and an anti-peek built-in code lock are demonstrated, which has promising potential in universal tactile sensing for motion monitoring, electronic skin, robotics, and human-machine interactions.

Evaluation of Ionizing Radiation Effects on Device Modules Used in Wireless-Based Monitoring Systems

To increase the reliability of wireless-based monitoring systems under ionizing radiation environments, multiple diversified commercial off-the-shelf (COTS) modules have been used to achieve radiation tolerance. This paper presents experimental results of radiation tests on key modules in wireless-based monitoring systems, which include analog signal processing circuits, analog-to-digital converter (ADC) modules, microcontroller modules, and wireless transmission modules. In total, 12 modules have been evaluated, (i.e. 3 analog modules, 3 ADCs, 3 microcontrollers, and 3 wireless transmission modules). The radiation tests are conducted using the gamma radiator at The Ohio State University Nuclear Reactor Lab (OSU-NRL). The performance parameters of these 12 modules are investigated under high dose rate (20 krad(Si)/h). Experimental results have shown that the tested modules perform satisfactorily with little sign of degradation until the total dose levels reach the tolerable limits for these modules. Experimental results support the fact that, by using diversified COTS components, one may be able to achieve equivalent performance as those built by using radiation-hardened components, but with a considerable cost-saving. Furthermore, the tests also show that digital modules, particularly, with higher speed processors (i.e. microcontrollers) may be more susceptible to radiation than other types of modules. Therefore, additional shielding should be used to protect them.

A Novel RFI Mitigation Method Using Source Rotation

This article proposes a novel radio frequency interference (RFI) mitigation method and applies it to a real consumer electronic device. Through near-field scanning, an equivalent dipole moment of the noise source containing the CPU and DDR memory chip is reconstructed. The near-field components of the victim Wi-Fi antenna are measured to obtain the transfer function. By determining the relationship between the dipole moment and the antenna near field, the noise source is rotated by a certain angle to reduce RFI. Rotating the source to reduce RFI is implemented in such a way that it does not compromise the signal integrity, and it does not require an additional shield can. New boards with the suggested changes are fabricated and the measured results show the RFI reduction up to 8 dB compared with the original board.

Shielding implications on secondary radiation doses in prostate cancer treatment

AbstractMedical linear accelerators (linacs) require a physical structure designed to provide adequate structural support which ensures the safety of patients, operators and the general public. During a radiotherapy session, healthy tissues are exposed to radiation, even with these safety guarantees. This unwanted exposure may increase the likelihood of developing secondary cancer. This work uses the MCNP-5 code to computationally simulate a conformational 3D radiotherapy protocol for prostate cancer. Also, it investigates the potential effects of radiotherapy room shielding composition on equivalent and effective doses in the patient’s body. A computational model of an actual room was developed considering a Varian Trilogy linac operating at 10 MeV. This model enabled dose calculations for an anthropomorphic phantom called REX to be performed. This phantom has sufficient details of all relevant organs and tissues needed to estimate the effective dose of the patient. The treatment protocol modeled in this study came from the database of patients treated by the Brazilian National Cancer Institute (Inca). For this protocol, the total dose to be applied to the patient is equally distributed over the four gantry inclination angles (0°, 90°, 180° and 270°). The simulated results suggested that the equivalent dose on different organs and tissues has been increased by concrete shielding. Regarding the effective dose due to the presence of additional shielding (steel or lead), the simulation suggests that such variations can be considered small. Overall the results allowed quantifying the specific contribution of concrete, lead, and steel as part of shielding on the equivalent and effective doses in the patient.

Magnetic Measurement of Electrically Evoked Muscle Responses With Optically Pumped Magnetometers.

Electroneurography has been an essential method for assessing peripheral nerve disorders for decades. During this procedure, a nerve is briefly electrically excited, and nerve conduction properties are identified by indirect means from the behavior of the innervated muscle. The magnetic field of the resulting muscle response can also be recorded by novel, uncooled magnetometers, which have become very attractive for different medical applications over recent years. These highly sensitive magnetometers are called optically pumped magnetometers. We performed unaveraged and averaged magnetic signal detection of electrically evoked muscle responses using optically pumped magnetometers. We then discussed the suitability of this procedure for clinical applications in the context of diagnostic value and in direct comparison with the current electrical gold standard. The magnetic detection of muscle responses is possible using optically pumped magnetometers. Our magnetic results (averaged and unaveraged) closely match those from electrical measurements. Optically pumped magnetometers provide an alternative, contactless technology for electrode-based motor studies, but they are currently not ready for routine clinical use. This costly technology requires additional earth magnetic shielding because this is a prerequisite for proper operation. Currently, there are no diagnostic advantages over electrical measurements. Additionally, the required measurement setup and procedure are much more complicated. In contrast to already published proof-of-principle studies for magnetomyography, we report in detail the results of the magnetic measurements of electrically evoked muscle responses in a shielded environment by applying supramaximal stimulation and finally validate our findings with electroneurography data as a reference.

Obezbeđivanje disajnog puta kod pacijenata sa COVID-19

SARS-CoV-2 virus causes COVID-19, which is characterized by a high level of aerosol spreading of viral particles. Aerosol generating procedures are high-risk procedures for anesthesiologists and necessities expensive high level protective personal equipment (PPE) (level 3). The problem with COVID-19 is the high number of patients, which presents an economic burden for the health care system and country, and causes issues with human and equipment resources. Airway protocols vary among hospitals like three gloves technique, videolaryngoscope, FFP3 masks, eye protection, and additional shield. All parts of the anesthesiologist's body need to be covered with protective equipment. Extubation is also considered as high risk from the point of aerosol production, and PPE level 3 is required. Patient monitoring for early warning signs leads to intubation, which is predicted and planned. The patient is preoxygenated, fully relaxed, without mask ventilation as rapid sequence intubation. The suggested time for intubation is 30 s, immediate cuff inflation, followed by a tube connecting with the machine for mechanical ventilation. Capnography serves for the tracheal intubation confirmation. Supraglottic devices and cryccothyteothomy are reserved for situation can't intubate-can't oxygenate. Airway procedures are considered as high-risk procedure, and the most experienced anesthesiologist should perform them in the shortest possible time. The best solution is to have an airway dedicated team, educated in simulation center for this specifiec type of intubation, proper planning, prepared and checked medications and equipment.

Commissioning Test of the Iradiator Gamma Merah Putih

Initialized with design phase in 2015, BATAN developed a gamma irradiator, namely the Iradiator Gamma Merah Putih (IGMP). Located in Puspiptek Serpong, the IGMP finished its construction in 2017. Commissioning test was performed for assuring that the installation is designed, constructed and installed according to the operational requirements. The commissioning test consists of cold and hot commissioning. Cold commissioning refers to testing the operation of the irradiator without radioactive sources. The test was carried out by doing a checklist on the operating table list. The test showed that in all operations, all irradiator equipment and systems are functioning well as per the requirements. It was then concluded that the irradiation facility was ready to receive radioactive sources. In July 2017, the gamma irradiator was loaded with 301 kCi of Cobalt-60 sources provided in 29 source rods distributed into three racks individually controlled by hoist mechanism. Hot commissioning was carried out by lifting up all radioactive sources, and then radiation exposures were measured. In the preliminary tests, there were some locations at the third floor, where the radiation exposures were too high. It was then be minimized by correcting the roof plugs positions and by adding lead material as additional shielding. Finally, measurements show that all radiation exposures were less than 1 μSv/h and safe for public.

Determination of backscattered neutrons/gammas from open beam port of a research reactor

Neutron and gamma dose rate calculations were carried out around horizontal beam tube no. 5 at the Jožef Stefan Institute (JSI) TRIGA Mark II research reactor. Results were compared to the experimental measurements in order to verify the computation model. In addition, another set of calculations and measurements was carried out, where an additional shield made out of concrete and paraffin was installed. With that configuration, we were able to study neutron and gamma scattering.

In vivo monitoring of total skin electron dose using optically stimulated luminescence dosimeters.

This study retrospectively analysed the results of using optically stimulated radiation dosimeters (OSLDs) for in vivo dose measurements during total skin electron therapy (TSET, also known as TSEI, TSEB, TSEBT, TSI or TBE) treatments of patients with mycosis fungoides. TSET treatments are generally delivered to standing patients, using treatment plans that are devised using manual dose calculations that require verification via in vivo dosimetry. Despite the increasing use of OSLDs for radiation dosimetry, there is minimal published guidance on the use of OSLDs for TSET verification. This study retrospectively reviewed in vivo dose measurements made during treatments of nine consecutive TSET patients, treated between 2013 and 2018. Landauer nanoDot OSLDs were used to measure the skin dose at reference locations on each patient, as well as at locations of clinical interest such as the head, hands, feet, axilla and groin. 1301 OSLD measurements were aggregated and analysed, producing results that were in broad agreement with previous TLD studies, while providing additional information about the variation of dose across concave surfaces and potentially guiding future refinement of treatment setup. In many cases these in vivo measurements were used to identify deviations from the planned dose in reference locations and to identify anatomical regions where additional shielding or boost treatments were required. OSLDs can be used to obtain measurements of TSET dose that can inform monitor unit adjustments and identify regions of under and over dosage, while potentially informing continuous quality improvement in TSET treatment delivery.

Additive manufacturing with the lightweight material aluminium alloy EN AW-7075

As a widely used additive manufacturing technique, the laser metal deposition process (LMD) also known as direct energy deposition (DED) is often used to manufacture large-scale parts. Advantages of the LMD process are the high build-up rate as well as its nearly limitless build-up volume. To manufacture large-scale parts in lightweight design with high strength aluminium alloy EN AW-7075, the LMD process has a disadvantage that must be considered. During the process, the aluminium alloy is melted and has therefore a high solubility for hydrogen. As soon as the melt pool solidifies again, the hydrogen cannot escape the melt and hydrogen pores are formed which weakens the mechanical properties of the manufactured part. To counter this disadvantage, the hydrogen must be successfully kept away from the process zone. Therefore, the covering of the process zone with shielding gas can be improved by an additional shielding gas shroud. Furthermore, the process parameters energy input per unit length as well as the horizontal overlapping between two single tracks can be varied to minimize the pore volume. Best results can be achieved in single tracks with an elevated energy input per unit length from 3000 to 6000 J/cm. To manufacture layers, a minimal horizontal overlapping will lead to lowest pore volume, although this results in a very wavy surface, as a compromise of low pore volume and a nearly even surface a horizontal overlapping of 30 to 37% leads to a pore volume of 0.95% ± 0.50%.

Simplified approach to reduce transient overvoltages on insulation regarding compaction of 400‐kV overhead transmission lines

The paper presents a methodology with a new simplified approach, as a set of procedures, aiming to optimize the insulation level when compacting 400‐kV overhead transmission lines (OTLs) in order to increase their operational reliability. The procedure initiates from presupposed requirements for compaction, as it is becoming increasingly more difficult to carry out reconstruction, revitalization, or construction of new OTLs while keeping the original design criteria. The main purpose of this approach is to reduce transients on the insulation, which are caused by direct lightning strikes to the tower top, and influence switching overvoltages using an additional shield wire on OTLs. The insulation leader progression model E50% and the dynamic ionization model Eion for grounding with the constant ratio between the tower grounding resistance Rg and specific ground resistivity ρg are used to evaluate the lightning transients. For the analysis, the switching overvoltages phase domain transmission line model is used, where OTLs are divided into a number of short segments. For the purpose of this investigation, a mathematical model of a double‐circuit compact OTL is implemented. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A Frequency-Selective EMI Reduction Method for Tightly Coupled Wireless Power Transfer Systems Using Resonant Frequency Control of a Shielding Coil in Smartphone Application

Current wireless power transfer (WPT) technology is widely used for various applications because of convenience and safety. However, WPT systems have problems with electromagnetic field (EMF) leakage, which can cause electromagnetic interference (EMI) issues for nearby electrical devices at various frequency ranges. In the case of the Qi standard that operates from 105 to 205 kHz frequency range, the third or fifth harmonic can cause EMI problems for the amplitude modulation bands of a radio corresponding from 530 to 1700 kHz. For the first time, in this article, we propose a frequency-selective EMI reduction method with an additional shielding coil for the effective suppression of EMI radiation of a WPT system. The proposed method reduces the EMI in a specific frequency range and has insignificant effect on the power transfer efficiency (PTE). We experimentally verified that the proposed method with the shielding coil reduced the EMF leakage by 8.96 dB of the third harmonics without reduction of the PTE. Furthermore, we mathematically designed the shielding coil using the proposed method. The mathematical calculation based on the equivalent circuit models is strongly correlated with the experimental measurement results.