Modeling and Simulation for Conducted Noise on AC/DC Converter Using SiC-Device

Wataru Kitagawa,Kohei Mitani,Yuki Kawamura,Takaharu Takeshita 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents method for deriving equivalent circuit of conducted noise occurred by the switching on isolated AC/DC converter. The simulation of the disturbance voltage is executed by using derived equivalent circuit. By confirming that the simulation results agree with the measurement results, the availability of proposed method is verified. The EMI filters are modeled by RLC circuit. By inserting the model, the simulation of the disturbance voltage is executed. By confirming that the simulation result agrees with the measurement result, the validity of equivalent circuit parameters is verified. In addition, the EMI filter is designed by the simulation result. The experiment with the EMI filter is executed. The noise level with the EMI filter are within the limit value (CISPR11) in all frequency ranges.

Characteristic Analysis and Optimization of Stator Structure in Electromagnetic Bone Conduction Devices Considering Artificial Mastoid

Yuki Kondo,Wataru Kitagawa,Takaharu Takeshita,Akihiro Masuda,Ryuhei Masuda,Masahiro Nakashima 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper describes the analysis of the characteristics of the electromagnetic bone conduction device in consideration to mechanical characteristics of human head. And, usefulness of analysis method is confirmed by comparison between result and experimental result. Moreover, the stator structure is optimized to improve the output power.

Shape Optimization for Flux Barrier of Synchronous Reluctance Motor by Using MOGP

Keiji Goto,Wataru Kitagawa,Takaharu Takeshita 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper describes shape optimization result by MOGP (multi-objective genetic programing) using multi objective functions. Synchronous Reluctance Motor (SynRM) is used for analysis model. In addition, this paper presents result of dimension reduction applied to optimization result which have high dimensional data.

Modeling for Conducted Noise Simulation Considering Switching Characteristics on AC/DC Converter

Kazuki Kuwana,Yuki Kawamura,Wataru Kitagawa,Takaharu takeshita 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper describes the modeling method to simulate conducted noises on isolated AC/DC converter using SiC devices. The equivalent circuit in simulation is calculated from measurement of leakage current. The modeling circuits of simulation are constituted RLC circuits and step voltage sources. This paper mentions higher precision modeling circuit considering switching characteristics which is voltage fraction time of switching.

Modeling Method for Conducted Noise from Power Converter for Power Line Communication

Naoki Kojima,Takato Hattori,Wataru Kitagawa,Takaharu Takeshita 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper describes a method for modeling the leakage current from a DC/DC converter to a power line and selecting an EMI filter that suppresses the effect on power line communications. The relationship between the leakage current flowing in the power line and the error rate of power line communication is measured, and the limit value of the leakage current that does not affect power line communication is determined. Since the leakage current flowing in the power line is an attenuated waveform, it is modeled in RLC series circuits, and an equivalent circuit is created. EMI filter is inserted in the simulation, and filter is designed to keep the leakage current within the limit value. The results were compared with experimental results to confirm the reliability of this method.

Insect’s intestinal organ for symbiont sorting

Ohbayashi, Tsubasa,Takeshita, Kazutaka,Kitagawa, Wataru,Nikoh, Naruo,Koga, Ryuichi,Meng, Xian-Ying,Tago, Kanako,Hori, Tomoyuki,Hayatsu, Masahito,Asano, Kozo,Kamagata, Yoichi,Lee, Bok Luel,Fukatsu, Tak National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.37

<P><B>Significance</B></P><P>In general, animals have a mouth for feeding, an anus for defecation, and a gut connecting them for digestion and absorption. However, we discovered that the stinkbug’s gut is functionally disconnected in the middle by a previously unrecognized organ for symbiont sorting, which blocks food fluid and nonsymbiotic bacteria but selectively allows passing of a specific bacterial symbiont. Though very tiny and inconspicuous, the organ governs the configuration and specificity of stinkbug gut symbiosis, wherein the posterior gut region is devoid of food flow, populated by a specific bacterial symbiont, and transformed into an isolated organ for symbiosis. Mutant analyses showed that the symbiont’s flagellar motility is needed for passing the host organ, highlighting intricate host–symbiont interactions underpinning the symbiont sorting process.</P><P>Symbiosis has significantly contributed to organismal adaptation and diversification. For establishment and maintenance of such host–symbiont associations, host organisms must have evolved mechanisms for selective incorporation, accommodation, and maintenance of their specific microbial partners. Here we report the discovery of a previously unrecognized type of animal organ for symbiont sorting. In the bean bug <I>Riptortus pedestris</I>, the posterior midgut is morphologically differentiated for harboring specific symbiotic bacteria of a beneficial nature. The sorting organ lies in the middle of the intestine as a constricted region, which partitions the midgut into an anterior nonsymbiotic region and a posterior symbiotic region. Oral administration of GFP-labeled <I>Burkholderia</I> symbionts to nymphal stinkbugs showed that the symbionts pass through the constricted region and colonize the posterior midgut. However, administration of food colorings revealed that food fluid enters neither the constricted region nor the posterior midgut, indicating selective symbiont passage at the constricted region and functional isolation of the posterior midgut for symbiosis. Coadministration of the GFP-labeled symbiont and red fluorescent protein-labeled <I>Escherichia coli</I> unveiled selective passage of the symbiont and blockage of <I>E. coli</I> at the constricted region, demonstrating the organ’s ability to discriminate the specific bacterial symbiont from nonsymbiotic bacteria. Transposon mutagenesis and screening revealed that symbiont mutants in flagella-related genes fail to pass through the constricted region, highlighting that both host’s control and symbiont’s motility are involved in the sorting process. The blocking of food flow at the constricted region is conserved among diverse stinkbug groups, suggesting the evolutionary origin of the intestinal organ in their common ancestor.</P>

Duality of PWM Strategies between Current and Voltage Source AC/DC Converters for Suppressing DC Ripple

Junpei Isozaki,Balaji Veerasamy,Wataru Kitagawa,Takaharu Takeshita 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper presents duality of PWM (Pulse Width Modulation) strategies for reducing the DC ripples between current and voltage source AC/DC converters. The authors propose the PWM strategy of a voltage source converter for reducing the DC current ripples using the PWM strategy of a current source converter. The validity of the duality of the PWM strategies between current and voltage source converters is verified by experiments.

Practice patterns of adjuvant therapy for intermediate/high recurrence risk cervical cancer patients in Japan

Yuji Ikeda,Akiko Furusawa,Ryo Kitagawa,Aya Tokinaga,Fuminori Ito,Masayo Ukita,Hidetaka Nomura,Wataru Yamagami,Hiroshi Tanabe,Mikio Mikami,Nobuhiro Takeshima,Nobuo Yaegashi 대한부인종양학회 2016 Journal of Gynecologic Oncology Vol.27 No.3

Objective: Although radiation therapy (RT) and concurrent chemoradiotherapy (CCRT)are the global standards for adjuvant therapy treatment in cervical cancer, many Japaneseinstitutions choose chemotherapy (CT) because of the low frequency of irreversible adverseevents. In this study, we aimed to clarify the trends of adjuvant therapy for intermediate/highriskcervical cancer after radical surgery in Japan. Methods: A questionnaire survey was conducted by the Japanese Gynecologic OncologyGroup to 186 authorized institutions active in the treatment of gynecologic cancer. Results: Responses were obtained from 129 facilities. Adjuvant RT/CCRT and intensitymodulatedRT were performed in 98 (76%) and 23 (18%) institutions, respectively. On theother hand, CT was chosen as an alternative in 93 institutions (72%). The most commonregimen of CT, which was used in 66 institutions (51%), was a combination of cisplatin/carboplatin with paclitaxel. CT was considered an appropriate alternative option to RT/CCRTin patients with risk factors such as bulky tumors, lymph node metastasis, lymphovascularinvasion, parametrial invasion, and stromal invasion. The risk of severe adverse events wasconsidered to be lower for CT than for RT/CCRT in 109 institutions (84%). Conclusion: This survey revealed a variety of policies regarding adjuvant therapy amonginstitutions. A clinical study to assess the efficacy or non-inferiority of adjuvant CT iswarranted.

Bacterial Cell Wall Synthesis Gene <i>uppP</i> Is Required for <i>Burkholderia</i> Colonization of the Stinkbug Gut

Kim, Jiyeun Kate,Lee, Ho Jin,Kikuchi, Yoshitomo,Kitagawa, Wataru,Nikoh, Naruo,Fukatsu, Takema,Lee, Bok Luel American Society for Microbiology 2013 Applied and environmental microbiology Vol.79 No.16

<P>To establish a host-bacterium symbiotic association, a number of factors involved in symbiosis must operate in a coordinated manner. In insects, bacterial factors for symbiosis have been poorly characterized at the molecular and biochemical levels, since many symbionts have not yet been cultured or are as yet genetically intractable. Recently, the symbiotic association between a stinkbug, <I>Riptortus pedestris</I>, and its beneficial gut bacterium, <I>Burkholderia</I> sp., has emerged as a promising experimental model system, providing opportunities to study insect symbiosis using genetically manipulated symbiotic bacteria. Here, in search of bacterial symbiotic factors, we targeted cell wall components of the <I>Burkholderia</I> symbiont by disruption of <I>uppP</I> gene, which encodes undecaprenyl pyrophosphate phosphatase involved in biosynthesis of various bacterial cell wall components. Under culture conditions, the Δ<I>uppP</I> mutant showed higher susceptibility to lysozyme than the wild-type strain, indicating impaired integrity of peptidoglycan of the mutant. When administered to the host insect, the Δ<I>uppP</I> mutant failed to establish normal symbiotic association: the bacterial cells reached to the symbiotic midgut but neither proliferated nor persisted there. Transformation of the Δ<I>uppP</I> mutant with <I>uppP</I>-encoding plasmid complemented these phenotypic defects: lysozyme susceptibility <I>in vitro</I> was restored, and normal infection and proliferation in the midgut symbiotic organ were observed <I>in vivo</I>. The Δ<I>uppP</I> mutant also exhibited susceptibility to hypotonic, hypertonic, and centrifugal stresses. These results suggest that peptidoglycan cell wall integrity is a stress resistance factor relevant to the successful colonization of the stinkbug midgut by <I>Burkholderia</I> symbiont.</P>