Katsunori Mizuno

The University of Tokyo | Todai · Graduate School of Frontier Sciences

Various sampling and monitoring strategies have been developed to assess marine habitats and life‐forms. However, the cost‐effectiveness of such survey methods (e.g. line intercept transects and autonomous underwater vehicles) is still not high. In this paper, a practical seafloor habitat mapping method combining a cost‐effective survey system (P‐S...

When selecting a suitable site for offshore wind farm, the impact on the marine environment is one of the most important issues. However, in most cases of the suitable sites selection, the distances from protected areas, spawning and wintering grounds of marine creatures are taken into account as environmental indicators, and there are few which ex...

The deep ocean is Earth’s largest habitable space inhabited by diverse benthic organisms. Infauna play crucial roles in shaping sedimentary structures, relocating organic matter, porewater chemistry, and hence biogeochemical cycles. However, the visualization and quantification of infauna in situ inside deep-sea sediment has been challenging, due t...

The investigation of cancellous bone using ultrasound measurements is not an easy task due to the solid complex trabecular structure filled with fluid-like bone marrow. It is expected that the ultrasound propagated in cancellous bone contains valuable information about the complex structure. In this chapter, the methods to derive useful information...

Ocean thermal energy conversion (OTEC) is a power generation technology that extracts energy from the temperature difference between deep seawater and surface water in the ocean. Currently, a 100 kW class OTEC demonstration project is underway on Kume Island, Okinawa, and a plan to increase water intake and introduce a 1 MW class OTEC plant is unde...

In Japan, which has a wide EEZ, there are high expectations for the potential of MRE. The spread of MRE may produce various effects such as eliminating dependence on other countries for energy supply and revitalizing local economies through business entry. On the other hand, consensus building with various stakeholders at the time of project develo...

Over the last 3 decades, a large portion of coral cover has been lost around the globe. This significant decline necessitates a rapid assessment of coral reef health to enable more effective management. In this paper, we propose an efficient method for coral cover estimation and demonstrate its viability. A large-scale 3-D structure model, with res...

In this article, the detection of an object buried in marine sediments is investigated. Using the results from a series of experiments realized in a tank filled with water and calibrated glass beads, we evaluate the performances for a wide range of the value of the ratio kd of the grain size to the wavelength (k is the wave number and d is the grai...

With the renewal of the basic disaster management plan in Japan, the transferring flood risk itself to insurance carriers is promoted by the Japanese government. An insurance company to which flood risks are transferred must assess infrequent flood risks to manage the overall risk of the company. Insurance systems may reach peak risk condition when...

The non-life insurance industry requires sophisticated storm surge risk assessment for risk management. In the United States, a stochastic storm surge risk assessment has been performed using a method with low calculation load called JPM-OS, but the calculation accuracy is lower than that of conventional method JPM. In the storm surge risk assessme...

Various methods have been developed and used for monitoring marine benthic habitats, such as coral reefs and seagrass meadows. However, the efficiency of general survey methods [e.g., line intercept transects and autonomous underwater vehicles (AUVs)] still is not high. In this article, we propose a practical coral-coverage estimation method combin...

It is important to understand and predict fish behavior to assess the impacts of coastal development on ecosystem or to conduct appropriate fishery management. In order to collect information for understanding fish behavior, we measured the environmental factors and the distribution of fish simultaneously by using fishing boats. The memory-type sen...

Fish monitoring in aquaculture farms is indispensable for managing the growth and health status of fish resources. However, it is unrealistic to expect humans to be able to perform monitoring at night, when standard optical cameras are generally inapplicable. Although sonar systems can be used at night, their practical applications are limited by t...

We investigated the effects of small-scale oscillation (SSO) on toxic Microcystis cells. The oscillating device was made of silicon with two axes that had a diameter of ∼40 mm, and a frequency of 2.5 Hz was observed at 150 rpm. The SSO was effective in inhibiting Microcystis growth. Microcystin release was not observed, whereas cell density barely...

Sulfide deposits with extremely high Au concentrations (up to 275 ppm; avg. 102 ppm, n = 15), high Au/Ag ratios (0.24, n = 15), and low Cu/(Cu + Zn) ratios (0.03, n = 15) were discovered in 2015 in active hydrothermal fields at a water depth of 760 m in a basalt-dominated submarine caldera in the Izu-Ogasawara frontal arc, Japan. Native gold grains...

It is concerned that storm surges amplified by climate change will increase damage in the future climate, and when a storm surge actually occurs, it is required to quickly understand the whole aspect of damage. The study examined two methods: 1) a loss function method, which is a conventional way; 2) a new method of early damage estimation using a...

Acoustic imaging using high-frequency ultrasound can be an effective survey method to clarify the distribution of asari clams, which live in a relatively shallow layer of sediment. However, the propagation of ultrasound dramatically changes depending on grain size, resulting in visibility deterioration of acoustic images. In this study, the effects...

Fish behavioral models can be a beneficial tool for appropriate fisheries management and environmental impact assessment of ocean development. Especially, modelling of fish migration which is affected by the surrounding environment would be crucial. In the present study, we implemented several migration models in fish behavioral simulations. For a...

The bone fracture healing mechanism of the low-intensity pulsed ultrasound technique is not yet clearly understood. In our previous study, the electrical potentials induced in bone were successfully measured by focusing on piezoelectricity in the MHz range. Bone is composed of collagen and hydroxyapatite and has strong anisotropy. The purpose of th...

The Philippines has one of the most diverse seagrass meadows in south-east Asia, with substantial dugong populations still existing. However, the seagrass population is decliningworldwide, and 30–40% of the seagrass areas in the Philippines have been lost in the last 50 years. The quadrat method by scuba diving has been widely used to study seagras...

The exploration of buried deposits under the sea sediment requires high directivity and low attenuation beams. The parametric sub-bottom profiler (PSBP) meets these requirements; moreover, it is comparatively small and can be easily mounted on autonomous underwater vehicles (AUVs). For this reason, we are developing a new PSBP system for AUVs. In t...

Small AUV “IK-A” equipped with IRSAS was developed for submarine hydrothermal deposits exploration. Observed IRSAS data could acquire the back scatter image and bathymetry. One of the features of the seafloor hydrothermal deposits is the chimney and the mound-like terrain. Back scatter image can distinguish these terrain and other terrains. IRSAS h...

Through-transmission measurements in cancellous bone in vitro often reveal two longitudinal waves. The velocities and amplitudes of fast and slow waves are related to bone microstructure and composition and may provide useful diagnostic information. Phase velocity and attenuation for fast and slow waves were measured as a function of propagation de...

The exploration of deposits buried under sea sediment requires high directivity and low attenuation beams. The parametric sub-bottom profiler (PSBP) meets these requirements. Moreover, it is comparatively small and can be easily mounted on autonomous underwater vehicles (AUVs), which are both highly stabile and able to operate close to the target....

Some marine mineral resources have been found in the waters surrounding Japan, but exploration techniques are still under development, and the amount of those resources is currently unknown. As part of these efforts, the Ministry of Education, Culture, Sports, Science and Technology launched the system development of their marine mineral resources...

We develop an effective method for exploring seafloor hydrothermal deposits using acoustic apparatus. The important thing for seafloor hydrothermal deposits exploration is to carry out the efficiently detailed exploration after narrowing down a promising area from a vast area by wide-area exploration. Here, we aim to establish such a method, by exa...

In order to assess hydrothermal deposits within the Japanese Exclusive Economic Zone to secure domestic marine mineral resources, we are developing and using five observation devices: Multi-Beam Echo Sounder (MBES), Sub-Bottom Plofiler (SBP), Remotely Operated Vehicle (ROV), Interferometric Synthetic Aperture Sonar (InSAS), and samplers. Although t...

A new observation method of fish classification by using acoustic video camera (ARIS) at 3.0 MHz center frequency was developed. Using the method, high-quality acoustic image was obtained. After getting the acoustic image of fish by ARIS, we utilized a method called Scale-Invariant Feature Transform (SIFT) [1] into fish classification instead of th...

Digging is necessary to detect plant roots under the water bottom. However, such detection is affected by the transparency of water and the working skills of divers, usually requires considerable time for high-resolution sampling, and always damages the survey site. We developed a new automatic non-destructive acoustic measurement system that visua...

This paper focuses on developing a NEW Autonomous Underwater Vehicle (AUV) equipped with Interferometric Real and Synthetic Aperture Sonar (IRSAS) for the exploration of submarine hydrothermal ore deposits. After the construction, the first sea trial carried out in Feb 2016. From successfully results, we feel certain that new AUV play an important...

This study reports an adaptation of acoustic sensing to detection of shellfish in the sediment. In this paper, we tried to detect Ruditapes philippinarum called asari in Japanese using a 1-MHz acoustic focus probe. Then, 2-D acoustic imaging of the shellfish in the sediment was performed, and the strong backscatter from the shell surface was detect...

We are developing a technique for the systematical exploration of submarine hydrothermal ore deposits. In the Izu-Ogasawara Arc area these deposits are usually characterized by the existence of tower-like vents 2∼20m high by 2∼5m wide. We are using a set of Interferometric Real Aperture Sonars (InRAS) to generate 3D acoustic images of the areas sur...

high-resolution imaging method Using a 25-MHz ultrasonic acoustic profile measurement was introduced, and the inner structures of Small fish were examined without body contact. Two types of fish were as experimental targets and measured using a focused probe 3-D acoustic imaging of inner and external structure, of the fish body was then performed,...

The through-transmission ultrasound signal in cancelous bone consists of two longitudinal waves, called the fast and slow waves. The conventional propagation model assumes that the wavefront of an ultrasound wave passing through a bone specimen is flat and that each wave arrives simultaneously at all the points on a transducer surface. To compensat...

Conventional, Bayesian, and the modified least-squares Prony's plus curve-fitting (MLSP + CF) methods were applied to data acquired using 1 MHz center frequency, broadband transducers on a single equine cancellous bone specimen that was systematically shortened from 11.8 mm down to 0.5 mm for a total of 24 sample thicknesses. Due to overlapping fas...

In this study, we try for fish classification using high resolution acoustic video camera at 3.0 MHz center frequency (ARIS). Newly observation method with wide in vertical and narrow in horizontal beam (WVNHB) was proposed for getting high quality acoustic image of swimming fish, and tested an image processing algorithm basing on Normalized Cross...

Most Hydrilla verticillata disappeared soon after planting in unsuccessful restoration efforts carried out at Lake Izunuma (northeastern Japan). Furthermore, the disappearance of aquatic plants has been speculated to be a result of crayfish predation. However, the precise cause remains unclear because of the low transparency of the lake water. In t...

The received signal in through-transmission ultrasound measurements of cancellous bone consists of two longitudinal waves, called the fast and slow waves. Analysis of these fast and slow waves may reveal characteristics of the cancellous bone that would be good indicators of osteoporosis. Because the two waves often overlap, decomposition of the re...

The goal of this study was to compare the results from two proposed methods for separating fast and slow waves from mixed-mode signals, one using Bayesian probability theory and one using modified least-squares Prony’s (MLSP) [Wear, J. Acoust. Soc. Am. 133, 2490–2501 (2013)], on measurements of cancellous bone. Ultrasonic through-transmission data...

The healing mechanism of bone fractures by low intensity pulse ultrasound is yet to be fully understood. There have been many discussions regarding how the high frequency dynamic stress can stimulate numerous cell types through various pathways. As one possible initial process of this mechanism, we focus on the piezoelectricity of bone and demonstr...

Around 15-20 Ganges river dolphins (platanista gangetica) inhabit the 12-km stretch from Karnavas to Narora Barrage in the Ganges river system. However, more than 10 dolphins were carried away downstream after the flood of June-July 2013. In order to urgently conduct a quick census to secure the dolphins in the original habitat, the existing compac...

A new integrated measurement system that combines the acoustic imaging sonar of DIDSON (Dual-frequency IDentification SONar) with concentrator lenses, motion sensors, and differential global positioning system (DGPS) was used to classify different species of aquatic plants and make three-dimensional (3D) mapping of them at shallow lake. In the fiel...

Fast and slow waves were detected in a bovine cancellous bone sample for thicknesses ranging from 7 to 12 mm using bandlimited deconvolution and the modified least-squares Prony's method with curve fitting (MLSP + CF). Bandlimited deconvolution consistently isolated two waves with linear-with-frequency attenuation coefficients as evidenced by high...

Fast and slow waves were detected in a bovine cancellous bone sample for thicknesses ranging from 7 to 12 mm using bandlimited deconvolution and the modified least-squares Prony's method with curve fitting (MLSP+CF). Bandlimited deconvolution consistently isolated two waves with linear-with-frequency attenuation coefficients, as evidenced by high c...

To investigate the relationship between ultrasonic backscatter and trabecular microstructure, ultrasonic backscatter measurements were performed on cylindrical bovine cancellous bone samples in vitro. The backscatter signals from different specimen angles were obtained by rotating the specimen at various central frequencies. The backscatter signal...

Wave propagation in a trabecular bone was experimentally investigated using an acoustic tube. For the purposes of this study, a cubic sample was gradually filed so the waveform change due to the sample thickness could be observed. The initial sample showed clear two-wave separation. As the sample became thinner, the fast and slow waves gradually ov...

The two-wave phenomenon, the wave separation of a single ultrasonic pulse in cancellous bone, is expected to be a useful tool for the diagnosis of osteoporosis. However, because actual bone has a complicated structure, precise studies on the effect of transition conditions between cortical and cancellous parts are required. This study investigated...

Conventional survey methods (e.g., surface surveys using optical video cameras and divers) have been widely used to detect aquatic plants and estimate their densities. However, these methods are affected by the transparency of water and observational skills of the divers and usually require considerable amounts of time for high-resolution sampling....

Visualization method using ultrasonic acoustic profile measurement was introduced and inner structures of small size fishes were examined. Detection of external and internal body surface were executed. Two kinds of fishes are chosen in this experiment and measured by using 25 MHz medical probe. Then signal processing and visualization of three-dime...

Low frequency mechanical studies have reported the contribution of stress-induced electrical potentials to bone metabolism. However, the healing mechanism of bone fractures by low intensity ultrasound is not yet clear. We demonstrate that bone can generate electrical potentials by ultrasound irradiation in the MHz range. Electrical potentials were...

We used two acoustic measurement systems to assess the state of a quay wall. Collapse and subsidence of quay walls at harbors are often reported, and the development of a diagnostic method to help prevent collapse has become a significant concern. Collapse normally occurs because of an air hole inside the quay wall. Therefore, a robust, accurate di...

The distributions and population dynamics of plant species are modified by environmental factors. The grazing intensity of herbivores may have major effects on aquatic plants. Lake Izunuma is located in the northeast of Japan and is one of the most famous wintering grounds for swans. The foraging activities of whooper swans (Cygnus cygnus) were obs...

Acoustic imaging sonar is used for species classification of the submerged aquatic plants at lakes. We used a measurement system that combined a high resolution acoustic imaging sonar, i.e., a Dual-frequency IDentification SONar (DIDSON) with two types of concentrator lens, motion sensors, and GPS receivers to quantify the underwater status of the...

Active acoustic monitoring system using a dual frequency identification sonar (DIDSON) is applied for the follow-up observation of aquatic biota after Hydrilla verticillata planting. The field experiment was performed in a small pond adjacent to Lake Izunuma (northern latitude of 38.43 degrees and east longitude of 141.04 degrees; surface area, 1,5...

We used two types of acoustic measurement systems to assess the state of quay wall. Collapse and subsidence of quay wall at a harbor are often reported and a diagnosis method to prevent the accident has become a significant concern. The collapse is mainly occurred by air hole inside the quay wall. Therefore, the more robust and accurate diagnosis s...

In this study, we used a new integrated measurement system that combines the acoustic imaging sonar of DIDSON (Dual-frequency IDentification SONar) with concentrator lenses, motion sensors, and GPS receivers to find and identify different species of aquatic plants. Two types of experiments were performed at two lakes in Japan: Lake Yamanaka and Lak...

For understanding the Ganges river dolphin's (Platanista gangetica) echolocation strategies and underwater behavior for a long-term span, targeting 15-18 Ganges river dolphins including calves, the annual long-term in-situ monitoring using the passive acoustic system (a 6-hydrophone array) has been conducted for 4 consecutive seasons, i.e. four mon...

The two-wave phenomenon reflects not only bone mass but also the complex bone structure of cancellous bone. We propose a new simple imaging technique based on the two-wave phenomenon for investigating the anisotropic structure of cancellous bone. A cylindrical specimen of cancellous bone was obtained from a bovine femur. The structure (alignment of...

Two-wave phenomenon, known as the wave propagation of fast and slow waves, has been observed in the cancellous bones when the ultrasonic wave propagates along the trabecular alignment. It is also reported that the acoustical parameters of the fast and slow waves related to not only bone mass but also bone microstructure. In this study, the characte...

After the successful observation of two wave phenomenon in cancellous bone, wave characteristics have been investigated by in vitro studies. However, there still exists strong necessity to understand the effects of bone boundary conditions on the phenomenon, because the cancellous bone is always covered by a cortical layer in vivo. This paper is de...

Longitudinal wave in cancellous bone separates into fast and slow waves depending on the alignment of trabeculae. Here, the fast wave mainly propagates in trabeculae, whereas slow wave propagates in the soft tissue (bone marrow). Because these two waves usually overlap, the evaluation of each wave has still remained difficult. In this study, then,...

Low-intensity pulsed ultrasound (LIPUS) is used on bone-healing. One expected healing mechanism of this technique is the contribution of piezoelectricity. Actually, the piezoelectricity in dry bone at low frequencies has been reported by many investigators. However, the ultrasonic investigation of the piezoelectricity in bone has still remained ver...

Two-wave phenomenon in cancellous bone has been reported by several investigators. Making use of this phenomenon, a new QUS device has been introduced to evaluate the radius in vivo. We have also reported that two waves reflect not only bone mass but also the complex bone structure of cancellous bone. We then propose a new simple imaging technique...

Bayesian probability approach with a simple model was introduced for the analysis of two wave propagation phenomenon in the cancellous bone. The fast and slow waves could be estimated from the experimentally observed wave. The reproduced wave made by these estimated fast and slow waves was compared with the initial experimental wave using a wavelet...

The effects of overlapping fast and slow waves on measurements of the apparent attenuation as a function of propagation distance are investigated along with methods of analysis used to determine the attenuation properties. Two methods are applied to simulated data. The first method uses a time-domain approach that was dictated by constraints impose...

Previous studies have shown that interference between fast waves and slow waves can lead to observed negative dispersion in cancellous bone. In this study, the effects of overlapping fast and slow waves on measurements of the apparent attenuation as a function of propagation distance are investigated along with methods of analysis used to determine...

Ultrasound propagation in cancellous bone (porous media) under the condition of closed pore boundaries was investigated. A cancellous bone and two plate-like cortical bones obtained from a racehorse were prepared. A water-immersion ultrasound technique in the MHz range and a three-dimensional elastic finite-difference time-domain (FDTD) method were...

The two-wave phenomenon in a cancellous bone surrounded by a cortical bone was investigated using the specimens obtained from large mammals. Measurements were performed using laboratory-built poly(vinylidene fluoride) (PVDF) transducers excited by a one-cycle sinusoidal wave at 1 MHz. In addition to the experimental ultrasonic measurements, the fin...

Longitudinal wave in cancellous bone separates into fast and slow waves depending on the structure of bone trabeculae (two wave phenomenon). The fast wave strongly depends on the structure of bone trabeculae, and the velocity varies due to the structure and propagation direction. In this study, we measured changes of ultrasonic waves after the prop...

The influence of cancellous bone microstructure on the ultrasonic wave propagation of fast and slow waves was experimentally investigated. Four spherical cancellous bone specimens extracted from two bovine femora were prepared for the estimation of acoustical and structural anisotropies of cancellous bone. In vitro measurements were performed using...