Engineering Research Association Research Articles

Development of a Composite Electrolyte Membrane with Chain-like Microstructure CeO2-Based Oxide for Achieving High Durability and Performance in Polymer Electrolyte Fuel Cells

Polymer electrolyte fuel cells (PEFCs) are expected to be applied in heavy-duty vehicles (HDVs), in which the operating temperature approaches around 120 ℃. The higher operation temperature, in comparison with that of passenger cars, leads to a significant decrease of the proton conductivity of perfluorosulfonic acid-based electrolyte membranes (PFSA, such as Nafion) under typical atmospheric conditions. Metal oxide surfaces, on which adsorbed water is stable even at temperatures exceeding 100 ℃, have the potential to maintain the water uptake at elevated temperatures, if the oxide is mixed with the PFSA membrane. In our Center, the improvement of proton conductivity over a wide temperature range has been confirmed in composite membranes prepared from Ta-TiO2 and Nafion.1) In the present study, Nafion / CeO2-based oxide composite membranes were fabricated to investigate their proton conductivity and microstructure, as well as to examine the durability of the electrolyte membrane.CeO2-based nanoparticles (CeO2, Nb-CeO2, Zr-CeO2) with chain-like microstructure were prepared by the flame spray pyrolysis method. Each type of nanoparticle was mixed with Nafion dispersion (20 wt.%, DE2020 CS, Chemours) at various ratios, coated and dried by use of a die coater apparatus, and then hot-pressed (140 ℃, 3 min.) to form a membrane. The microstructure was observed by scanning electron microscopy (SEM), small angle X-ray scattering (SAXS), and transmission microscopy (TEM). The proton conductivity was measured by the four-probe alternating current method, and water uptake was measured by a water vapor adsorption method. Additionally, the open circuit voltage of a single cell with the fabricated composite membranes (OCV test) was characterized to confirm the durability of the membrane.The proton conductivity of a composite membrane with 3 wt.% Nb-CeO2 was 1.3 times higher than that of commercial Nafion (NRE211, Chemours) at 80 ℃ and 80% RH, and 1.6 times higher at 80 ℃ and 20% RH. The water content of the composite membranes was independent of the Nb-CeO2 content, and the intensity of a SAXS peak for water clusters (ca. 3 nm) was comparable to that of Nafion under all relative humidity conditions. OCV durability tests using composite membranes with 3 wt.% Zr-CeO2 maintained high OCV values up to 1500 hours of operation, even though unmodified Nafion membranes were unable to maintain high OCV values for more than 250 hours. These results indicate that even small amounts of CeO2-based oxide can improve the proton conductivity and the chemical stability. Acknowledgement This work was partially supported by the New Energy and Industrial Technology Development Organization (NEDO). The results of the OCV test were evaluated by the Fuel Cell Cutting-Edge Research Center Technology Research Association (FC-Cubic). Reference (1) Ohno, K. Shudo, T. Tano, and K. Kakinuma, ACS Appl. Energy Mater., 6, 10098-10104 (2023).

System Resilience of a Liquid Hydrogen Terminal During Loading and Unloading Operations

Hydrogen technologies are playing an increasing role in transportation and industry. Key for taking maximum advantage out of the great gravimetric energy density of hydrogen are feasible and safe storage and transfer concepts. For the successful implementation of a hydrogen-based society with several green industrial initiatives, it is indispensable to develop an infrastructure of liquid hydrogen (LH2) terminals and tanker ships with the capability to bunker LH2. Liquid hydrogen might be used to store and transport large quantities of hydrogen. LH2 is a cryogenic fluid, so double-walled vacuum insulated tanks are required to keep it cold for long periods of time until further distribution or use. Whether transportation sector or industry, to date there is little knowledge on safety related issues available. Main concern when handling hydrogen are accidental releases that can lead to integrity damage on materials and structures, fires, and explosions. Assuming that LH2 infrastructures will be widely deployed and in use all over the globe, accidents are possible to occur during loading and unloading of LH2 bunkering facilities. Therefore, it is necessary to conduct a detailed risk assessment that focuses on system resilience to improve the capabilities of the facility to keep its functionality up when errors occur. This study refers to the LH2 storage tank installed in the LH2 terminal in Kobe, Japan. This stationary storage tank is an essential element of the terminal that was constructed by the Hydrogen Energy Supply Chain Technology Research Association (HySTRA). HySTRA aims at the distribution of hydrogen in liquified form by ship from Australia to Japan. To date, there is only little data available regarding the facility in Kobe. Nevertheless, due to the novelty of the technology the risk for accidents to occur might be higher than in conventional fuel distribution terminals. Accidents might happen due to technical failures, human errors, or external causes such as natural events. The consequences could be catastrophic. Some of these may expose structures and personnel to extreme low temperatures, fires, and explosions which may hinder bunkering operations of the facility in Kobe. This study gives an overview on possible scenarios that lead to loss of containment and provides an insight in the process of evaluating system resilience during such a scenario. This work details with a framework for assessing system resilience applied to LH2 storage facilities. The system resilience calculation involves the examination of a critical hydrogen accident database and provides suitable preventive and mitigative safety barriers.

Combined sensory integration therapy plus neurodevelopmental therapy (NT) versus NT alone for motor and attention in children with Down syndrome: a randomized controlled trial

In this study, we aimed to analyze the incremental effects of sensory integration therapy (SIT) plus neurodevelopmental therapy (NT) versus NT alone on the attention and motor skills in children with Down syndrome (DS). We randomly assigned into experimental (i.e. SIT + NT; n = 21) and control (i.e. NT alone; n = 21) groups. While NT was applied to both groups for six weeks, SIT was applied simultaneously to the experimental group for six weeks. Participants’ motor functions (Bruininks-Oseretsky Test of Motor Proficiency-Short form (BOT-2 SF)) and attention skills (Stroop TBAG (Turkish Scientific and Technological Research Association) Form) were evaluated before and after treatment (6 weeks later). Stroop TBAG and BOT-2 SF scores of the groups were similar at the baseline (p > 0.05). Significant improvement from baseline was observed in both BOT-2 SF, and Stroop TBAG results in both groups (p < 0.05). In addition, the improvement in both BOT-2 SF and Stroop TBAG results was found to be greater in the experimental group compared to the control group (p < 0.01). There were clear advantages to adding SIT to NT alone when seeking to improve motor and attention skills in children with DS.

Investigation on High Reliability Wireless Communication of Underwater Sensor Networks for Submerged Acoustic Correspondence

The Marine Corps (UWSN) Classification Society and Advanced Information Resources Research Association cooperate with the Information Technology Research Association. Communication Technology Foundation and Ocean Culture Foundation. Notwithstanding, contrasted and the earthly condition, the marine condition is intricate and inconsistent, so correspondence in this condition is extremely troublesome. This article has directed a top to bottom conversation and survey of submerged specialized techniques and organization advances, (for example, submerged acoustic correspondence, submerged optical correspondence, and steering conventions and media access control). (Macintosh) and submarine multimodal transport organizations. This article additionally talks about the accomplishments of high-unwavering quality submerged correspondence innovation, and there are not many difficulties in managing submarine organizations.

Progress of the brown coal derived hydrogen supply chain demonstration project

The world has changed its direction widely towards the realization of the CO2-free society by the Paris Agreement issued in 2015. In Japan, prior to the Paris Agreement, the usage of large amount of hydrogen was proposed by the several sectors through the hydrogen and fuel cell strategy road map issued in June, 2014. Also, the Prime Minister Suga declared the realization of carbon neutral by 2050 at the time of his policy speech in October, 2020 and demonstration of CO2-free hydrogen supply chain became urgent need. Under those situations, CO2-free Hydrogen Energy Supply-chain Technology Research Association has been established by the four companies comprises Iwatani Corporation, Kawasaki Heavy Industries Ltd., Shell Japan Limited and Electric Power Development Co., Ltd. in 2016 towards the realization of commercial hydrogen supply chain in 2030. At the moment, research and development（R&D） has been carried out for the demonstration in 2021 through the adoption of Demonstration Project for Establishment of Mass Hydrogen Marine Transportation Supply Chain Derived from unused Brown Coal funded by the subject setting type industrial technical development subsidy of NEDO.

RIKEN Accelerator-driven compact Neutron systems, RANS project -RANS, RANS-II, III, RANS-μ-

RIKEN Accelerator-driven compact neutron source, RANS, has been operational since 2013. There are two major goals of RANS research and development. One is to establish a new compact low energy neutron non-destructive evaluation system on-site of floor-standing type for industrial use. Another goal is to invent a novel transportable compact neutron system for the preventive maintenance of large scale construction such as a bridge. For the realization of the preventive maintenance usage with neutron methods for non-destructive test of large scale structures on-site, “Standardization”, such as inclusion in manuals and inspection procedures, is essential. Technology research association for the infrastructure preventive maintenance standardization is established. RANS and RANS-II are in operation, and RANS-III, and RANS-μ, neutron salt-meter, are under development.

A Comparison between Artificial Intelligence Method and Standard Diagnosis Methods for Power Transformer Dissolved Gas Analysis Using Two Public Databases

Oil‐filled power transformers play an important role in modern network systems. Stable power supply can be achieved by early detection of power transformer faults and continuous monitoring of equipment. In recent years, dissolved gas analysis (DGA) has been widely used to diagnose faults in power transformers. Although DGA is an easier and simpler method for the fault diagnosis of transformers, different techniques usually provide different results with real‐world data. In fact, conventional diagnosis approaches for power transformers depend on human experience and available technology of human experts. Therefore, we propose using an artificial intelligence (AI) technique called multilayer perceptron (MLP) for the intelligent diagnosis of power transformer faults. In this work, the MLP model is constructed using the Keras library. The method is tested using two public databases: one based on the Electric Technology Research Association of Japan (ETRA) database and another based on the IEC TC10 database. Results indicate that high‐prediction accuracy is achieved. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Development of Sunlight Driven Water Splitting Devices towards Future Artificial Photosynthetic Industry

The ongoing research and development of sunlight-driven water splitting in the “Japan Technological Research Association of Artificial Photosynthetic Chemical Process (ARPChem)” is overviewed. Water splitting photocatalysts, photoelectrochemical devices, large-scale reactor panels, product gas transportation, H2/O2 gas separation devices and safety measures against explosion are included as the research objectives. ARPChem was formed as a research union of Japan’s leading chemical firms, in which related elementary technologies have been cultivated. This article introduces our general scope for artificial photosynthesis and describes present research activities, mainly on solar driven water splitting photocatalysts/photoelectrodes and briefly on the processes and plans for plant construction for future industrial extension.

Ballard modules used in successful Yanmar boat test in Japan

Two FCveloCity®-MD 30 kW modules supplied by Canadian-based Ballard Power Systems have been successfully integrated and tested in a hybrid marine application in Japan. The consortium includes industrial equipment and engine manufacturer Yanmar Co Ltd, the National Maritime Research Institute (NMRI), and the Japan Ship Technology Research Association (JSTRA).

Development of a New Fabrication Route for High Quality Visible-Light-Driven Photocatalysts; Atmosphere Controlled Flux Growth for Oxynitride and Nitride Crystals

Photocatalysts and related materials have been attracted a number of research interests due to their various application such as decomposition of organic substances, superhydrophilic surfaces, dye-sensitized solar cells, and hydrogen production by water splitting. In particular, water-splitting by photocatalysts have been investigated because of expectation to supply clean and recyclable hydrogen energy. Generally, photocalysts, as represented by TiO2, are activated by only ultraviolet light illumination due to their wide band gap. Although these UV-light-driven photocatalysts can split water in a proper condition, the solar energy conversion efficiency is rather low because UV light energy is just several percent in total energy of sun light on the earth, and visible light accounts for almost half of the solar energy. From the viewpoint of increase the efficiency and industrial application of solar hydrogen production, visible-light-driven photocatalysts have intensively attracted research interests. In particular, oxynitride and nitride semiconductor photocatalysts are one of promising materials for construction of photocatalytic water splitting systems. Although visible-light-driven photocatalysts with sufficiently small band gap, an appropriate band gap position for water splitting, and stability during the reaction have been developed, it is still required to improve the quantum yield. Generally, lattice defects are not suitable for photocatalysts with high performance because they would become recombination centers of excited carriers. Flux method is a liquid phase crystal growth technique which uses molten metals or molten metal salts as solvents. Flux method can afford binary or multicomponent high-quality crystals at lower temperatures below their melting points. It is interesting that flux-grown crystals usually have idiomorphic shapes with well-developed facets, which represents their high crystallinity. In addition, it provides simple, low-cost and environmentally-benign pathway compared to conventional solid-state-reaction method. Therefore, flux growth is a promising way to prepare high-quality visible-light-driven photocatalyst crystals. Herein, we present growth of oxynitride and nitride crystals for photocatalysts through atmosphere controlled flux method. LaTiO2N, Ta3N5, SrTaO2N, BaTaO2N, and BaNbO2N (and many kinds of oxynitrides and nitrides) crystals were grown under NH3 flow with using flux. Especially LaTiO2N crystals were directly grown from KCl flux and exhibited higher oxygen evolution performance compared to those prepared by conventional methods. It is attributed to elongated lifetime of excited carriers which detected by time-resolve IR spectroscopy. The flux growth is applied to crystal layer (i.e., thin and thick films) fabrication technique and then various photoelectrode consisting of the above-mentioned photocatalysts and current collector were fabricated. The details of flux growth and evaluation (e.g., photocatalytic performance) of the oxynitride and nitride crystals will be presented in 233rd ECS Meeting. This research was supported in part by the Japan Technological Research Association of Artificial Photosynthetic Chemical Process (ARPChem), NEDO and JSPS Grant-in-Aid for Scientific Research (A) 25249089.

Calculation of Seebeck Coefficients for Advanced Heat Transfer Modules

Advanced thermal control technologies have been required for power generation method and electric/hybrid vehicles. In the power devices, a high density of electric power within the small size (a few mm2) and their small heat capacity raise the temperature instantaneously. However, because hybrid vehicles have a limited space for an equipment of electric power conversion systems, the electrical modules for them should be as small as possible. This trend would continue to demand smaller size of power devices in near future. Therefore, it is required to provide faster response of cooling systems. One of the methods to realize this is Peltier cooling. The conventional Peltier devices are mainly applied to such as cold storage chambers. Because the function of the conventional device makes something a lower temperature than that of neighboring ambient, it is generally concluded that the thermal conductivity of the Peltier devices should be low. In contrast, in order to suppress the increase of the temperature of the power devices, Peltier devices should have a high thermal conductivity. Thus, we focused on silicon (Si), which thermal conductivity and Seebeck coefficient are high, as a material of the Peltier devices. The calculated power factor of Peltier effect (σS 2) of Si has a maximum when the carrier density is within 1018- 1019 cm-3. With such a carrier concentration of bulk Si, a contact resistance between Si and electrode metal may be not negligible. Therefore, it is necessary to apply the technologies for decreasing the contact resistance, such as higher carrier doping or metal-silicidation. Moreover, an application of Si-based Peltier devices for power devices requires optimizations of the structure of cooling system by predicting the cooling performance. Specifically, it is necessary to calculate the Seebeck coefficient, resistivity, and thermal conductivity of the Si-based Peltier devices with layered structures. In fact, some of reports have discussed the dependencies of electrode metals on these properties of Si. However, there are few reports on quantitative evaluation about the mechanism or the mechanism of electrode dependence of the Seebeck coefficient. Therefore, in this research, we calculated the Seebeck coefficient by using 3D model, and investigated the effect of interface layer between metal and Si. The structure of the Si sample for the calculation is the following: two electrodes with 2.0 mm × 0 .5 mm were deposited on the both ends of the Si substrate with the size of 2.0 mm × 15.0 mm × 0.625 mmt. It was assumed that the interface layer is formed between these electrodes and Si substrate. In addition, we investigated the influences of the Seebeck coefficient, resistivity, and thermal conductivity of the interface layer on the total Seebeck coefficient of the whole system. This total Seebeck coefficient was calculated by measuring potential difference ΔV between the two electrodes of a sample with a temperature difference ΔTof 50 K. These calculations revealed that resistivity of the interface layer do not affect the total Seebeck coefficient. On the other hand, our experimental results showed that the total Seebeck coefficient depended on the composition of electrodes (a silicide or metal) on Si. In order to explain this discrepancy, other factors which dominate the Seebeck coefficient, such as a work function of electrodes, would be taken into account. This research is supported by “Thermal Management Materials and Technology Research Association (TherMAT)” in New Energy and Industrial Technology Development Organization of Japan. Figure 1

(Invited) Peltier Effect of Silicon for Cooling 4H-SiC-Based Power Devices

All of power devices release high heat energy. In order to transport heat from them by a Peltier device, the direction of the heat flow should be taken into account. Because the temperature of heat drain is normally lower than that of the power devices, the direction of its Peltier effect is the same as that of thermal diffusion. Therefore, if the device consists of n Peltier blocks with its Seebeck coefficient S and thermal conductance K P, the total heat transport q all under an operation current I P with a temperature difference ΔT can be written as q all = n|S|TI P − (1/2)R P I P 2 + K PΔT. The parameters T and R P denote an average absolute temperature and an electrical resistance of the Peltier device, respectively. This means that both higher S and higher ΔT are required.Another important factor is a response time (τ P) of Peltier effect. Most of power devices release heat with high fluctuations. To flatten the time dependence of the temperature of the power chip, the τ P should be small enough to follow the heat fluctuations. However, even for well-known Bi2Te3 systems, only a few reports have discussed its τ P. Therefore, we studied a transient state of Peltier effect for a piece of n-type single crystalline Si, within a few seconds after the device was switched on.For estimating transient behavior, we used the single crystalline n-Si (100) (100 mm2 × 0.625 mm) with both of surfaces covered with Al/Pt/PtSix films. Silicon crystal (Si) has a large Seebeck coefficient and a high thermal conductivity.During measurements, the n-Si was sandwiched by a couple of gold blocks connected to a current source. Voltage and temperature were measured near an interface between the block and the n-Si. One of the blocks was connected to ceramic heater and the other to a refrigerator. In addition, to estimate an operation of the n-Si on a 4H-SiC-based power device, the Peltier effect with a 4H-SiC substrate was tested. A 4H-SiC substrate (100 mm2 × 0.35 mmt) and a strip of Cu were inserted between the gold block at the heat source and the n-Si. Because this 4H-SiC is an electric insulator, the current path is through the right Cu strip, right gold block, the n-Si, and the center Cu strip. InGa-based liquid metal was painted between all of the components.For deriving thermoelectric parameters, we analyzed time dependence of the difference between both sides of the n-Si, ΔT P(t) (≡ T D(t) − T S(t) − ΔT(0); where T D(t) and T S(t) denote the temperatures of heat drain and source, respectively), based on a series thermal circuit. We employed the expression of ΔT P(t) ≈ q P R HSi{1−exp(−t / τ P)} + q U R HU{1−exp(−t / R HU C HU)} − (q D / C HD)t, where q P (≡ STI P) and τ P denote an active heat transport and a response time by the Peltier effect, respectively. The second and third terms show an expansion and a reduction of ΔT P(t) by thermal diffusion, respectively. We found the equation of ΔT P(t) successfully represented all of the experimental ΔT P(t). The fitted parameters were summarized in Fig 1 (a) and (b). The Seebeck coefficients derived without and with SiC were −490 ± 20 μV/K and −571 ± 12 μV/K, respectively, which were consistent with that reported previously. The response time τ P obtained experimentally without and with SiC were ~ 0.1 sec and 0.15 sec, respectively. These short response time would enable a quick cooling of a heat source such as inverters. Finally, a simple simulation revealed that the parameters of ΔT P(t = 5 sec) and τ P for a bulk Bi2Te3 with the same arrangement in this work were 10 K and 2.5 sec, respectively. This shows that Bi2Te3-based Peltier device is not suitable for cooling a power device.Furthermore, as the second stage, the influence of metal electrodes on the thermoelectric properties of silicon has been evaluated. Titanium, aluminum, and platinum were used as an electrode of n-Si. Some of them were sintered to form films of silicides. A conventional measurements of voltage/temperature difference during steady state revealed that their Seebeck coefficient strongly depends on all of the composition, thickness, and sintering temperature.This research is supported by “Thermal Management Materials and Technology Research Association (TherMAT)” in New Energy and Industrial Technology Development Organization of Japan. Figure 1

Conducted EMI Analysis of Vehicle Positioning System and Strategies to Reduce Conducted EMI

The main objective of this research proposal is to measure the Conducted Emission (EMI) and propose mitigation techniques in order to meet the Electromagnetic Compatibility (EMC). For this research work, GPS based Vehicle Positioning System has been taken as a model. The Conducted Emission (CE) test on GPS based system has been performed at the Centre for Electronics Test Engineering, Pune and Automotive Research Association India Pune, India. This model was first tested without Radio Frequency Interference (RFI) filter. The EMC standard is specified for the frequency range of 150 kHz to 108 MHz for Conducted Emission measurement. The RFI Filter is proposed, as a one of the technique to reduce CE level. The CE level has been reduced significantly by using proposed RFI Filter. The results obtained were compared with the CISPR 25, SAE J1113 Automotive standard in order to investigate the effectiveness of the applied EMI filtering mitigation technique. The analysis and experimental results finally shows that the Conducted Emission has been reduced by around 30 dB using the RFI filter, making the system compatible with the EMI/EMC Standard.

Study of Radiated Emission from Wireless Positioning System and the Strategies to Minimize the Radiations

The objective of this research work is to develop Wireless Positioning System compatible with CISPR EMI/EMC standard. The system should work satisfactorily under dynamic and environmental conditions related to automotive platforms. This paper presents the measurement of Radiated Emission from GPS based Wireless Positioning/Localization System. It also deals with the implementation of the shielding techniques in order to make the system compatible with the EMC requirements as per CISPR EMI/EMC Standard. In the current scenario, the GPS based Wireless Positioning System is an essential part in the application areas such as logistics, public transports, naval ships, railways and stringent environment like defense vehicles. Due to its usefulness in daily life, the system has been considered as the test model for this research work. The reliability prediction for the model has been done with MTBF and Failure Rate estimations. The Radiated Emission level has been investigated for GPS based Vehicle Positioning System at the Centre for Electronics Test Engineering, Pune, India and Automotive Research Association of India (ARAI), Pune, India. This model was first validated in the GTEM Cell and further it was tested in the EMI chamber. It has been observed that RE level at certain frequency bands was found to be exceeding the specified limits as per the EMC standard. In this paper, few innovative techniques like shielding with enclosures has been proposed and implemented to reduce the level of radiated emission. The shielding enclosure of aluminum and copper were designed and implemented. Also, simulation of the stress level has been done for the copper enclosure with ANSYS software. The results of re-validating the GPS based system with aluminum and copper enclosures are presented here. After re-validation, radiated emission level was found to be reduced by around 10–40 dB making the system compatible with the EMI/EMC CISPR standards.

The Objectives of a National Project of &amp;#x2018;Manufacturing Innovation through Development of Next Generation 3D Printers&amp;#x2019; in Japan

Technology Research Association for Future Additive Manufacturing (TRAFAM) was established in 2014 to achieve the development of innovative additive manufacturing systems to meet the world's highest standards and the development of manufacturing technologies for high value-added products. In this presentation, the current status of the TRAFAM project is introduced.

Integrated power transformer diagnosis using hybrid fuzzy dissolved gas analysis

For diagnosing power transformer faults, this study uses hybrid fuzzy technology to integrate five dissolved gas analysis (DGA) approaches: IEEE Standard Doernenburg and Roger ratio methods, IEC60599 Standard ratio method, Electric Technology Research Association of Japan (ETRAJ) Standard ratio method, and Duval triangle method. The IEC TC 10 database and substation equipment maintenance and management web system (SEMMWS) of Taiwan Power Company (TPC) are then used for simulation and verification. Practical cases demonstrate that the integrated approach is more accurate than conventional methods. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Global convergence on the bioethics of surgical implants.

The increasing globalization of mankind with pluralistic belief systems necessitates physicians by virtue of their profession to partner with bioethics for soundly applying emerging knowledge and technologies for the best use of the patient. A subfield within medicine in which this need is acutely felt is that of surgical implants. Within this subfield such recent promising ethics and medicine partnerships include the International Tissue Engineering Research Association and UNESCO Chair in Bioethics and Human Rights' International Code of Ethics. In this paper, we provide an overview of the emerging human rights framework from bioethics and international law, discussion of key framework principles, their application to the current surgical challenge of implantation of surgical mesh for prolapse, and conclusions and recommendations. Such discussions are meant to facilitate true quality improvement in patient care by ensuring the exciting technologies and medical practices emerging new daily are accompanied by an equal commitment of physicians to ethically provide their services for the chief end of the patient's good.

S1920105 ほどよし3-4号機の開発と軌道上運用から得られた実践的な知見とその応用

Since June 2011 to end of March 2014, The University of Tokyo and The Next Generation Space system Technology Research Association had been developing the twin micro-satellite: Hodoyoshi-3 and -4 to demonstrate and establish an innovative system design and a cost-effective development process for mass-production of micro-satellites in the future based on the new concept called "Hodoyoshi" which means reasonably reliable. These two satellites were successfully launched into Sun Synchronous Orbit with an altitude of about 630km on June 19th 2014. So far, we have been getting achievements regarding system performance on-orbit, a lot of mission data, for example, Earth observation images and movies, technical demonstration by new devices, capabilities for new space utilization like space advertisement. In this project, we have been considering and demonstrating, system architecture design methods, integration and test process, on-orbit operation methods including recovery functions from anomaly. This evaluation is undergoing by reviewing operation results from viewpoints of Hodoyoshi concept. This paper descries the Hodoyoshi concept, the major characteristics of the satellites, and the key features and approaches of microsatellite development to realize cost-effective mission.

E02 共通超小型衛星バスの粗三軸制御安定性能の軌道上評価及び比較(宇宙システム・衛星技術)

This paper shows the design concept and the preliminary report for the low-accuracy three-axis stabilization results of the newly developed standard micro satellite system. The standard bus system is developed by the University of Tokyo and NESTRA (next generation space system technology research association) supported by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program). The satellite system tries to be straightforward to achieve cost-effective and short development period. The standard satellite systems are used as the bus system of three satellites launched in 2014, which are UNIFORM-1, HODOYOSHI-3, and HODOYOSHI-4. All of them have been achieved the low-accuracy three-axis stabilization, by dealing with the unexpected problems with the use of the modified operational plans. This paper also performs the comparison of the on-orbit results of three satellites and discusses the design feasibilities of the proposed bus system.

Fracture control of extremely thick welded steel plates applied to the deck structure of large container ships

The rapid enlargement of the size of container ships has led to the application of extremely thick plate in the deck structures, which may grow concerns about the fracture toughness at the butt-weld with large amount of heat input, and the arrest toughness of brittle crack propagation in the base metal of such thick plates. Also, slam-induced whipping stresses might affect the fatigue crack propagation and the initiation of a brittle crack in a container ship. In order to prevent the catastrophic failure of deck structures by brittle fracture, national joint research projects, which focused on the safety-related issues of extremely thick steel plate applied to hull of large container ships, were formed from April 2007 to March 2011 organized by the Japan Ship Technology Research Association (JSTRA) supported by the Japanese Government in collaboration with universities, national research institute, classification societies and relevant industries including shipbuilding, steel manufacturing and shipping companies. The joint research projects have carried out the investigations on crack initiation toughness of the weld, fatigue crack propagation under seaway loading, the potential of defect detection by ultrasonic testing, and the crack-arrest methods after brittle crack propagation. Practical recommendations to prevent brittle fracture of large container ships were proposed based on these comprehensive investigations. The essential parts of the above research activities are presented in this paper.