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Information and Communication: 36
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Nano Knowledge Exploration Project
Knowledge discovery from experimental records of nanocrystalline devices
In this research, we are studying knowledge management to extract and organize useful information for device development from experimental records and papers compiled in the process of research and development of nanocrystal devices.
Research
In this presentation, we propose an experiment record management system based on interviews with researchers in actual nanocrystal device development. The system proposes an integrated method for the management of records of parameters used in experiments that have been stored and recorded separately, as well as the resulting experimental records. In addition, by extracting information from the paper summarizing the final experiment, we propose a method for analyzing the purpose and characteristics of a series of experiments conducted by researchers in detail, and for using it as the basis for discussing similarities between various cases. With this method, we are proposing a method of extracting useful information from unknown papers by using machine learning methods on a corpus of information manually extracted by a few people.
Masaharu Yoshioka Professor -
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A method to evaluate radio wave propagation characteristics of in-vehicle wireless access services by large-scale electromagnetic field analysis
Toward optimal design of wireless environments
We have conducted research in various fields where radio waves are applied, including the evaluation of complex and special propagation environments in airplanes and passenger railroad cars, internal exposure of the human body to radio waves, electromagnetic interference evaluation and mechanism estimation regarding body medical devices implanted in the body, and evaluation of electromagnetic field leakage in wireless power supply devices for electric vehicles.
Research
The radio propagation environment inside a vehicle is a special environment that differs from the conventional propagation model due to multiple reflections caused by the surrounding metal and the presence of fixtures and passengers inside. It is therefore necessary to evaluate the characteristics of radio wave propagation, including the effects of absorption and scattering of radio waves by the bodies of passengers, to estimate the quality of the wireless connection under actual operational conditions. However, it is difficult to evaluate the propagation characteristics by actual measurement or simple numerical analysis (e.g., ray tracing). This study addresses modeling of the propagation environment in vehicles, which has been difficult in the past, and realizes a simulation method in a very large analysis space by using a supercomputer.
Takashi Hikage Associate Professor -
Academic Intercloud
Promoting research and development through academic cloud collaboration
We promote research to create an academic intercloud that links nationwide cloud systems, and conduct joint research on cloud-related technologies such as the optimization of resource allocation in intercloud environments and linkage between supercomputers and interclouds.
Research
Hokkaido University Information Initiative Center has established the Hokkaido University Academic Cloud, one of the largest academic clouds in Japan, and provides cloud services to researchers nationwide, including those concerning virtual and physical machines and their cluster systems, high-speed high-capacity cloud storage services, and machine learning and big data processing systems for research and development. We are also promoting research on fundamental technologies to realize nationwide cloud system collaboration and system construction to support researchers. Specific examples include the development of infrastructure technologies for cloud collaboration (authentication collaboration, etc.) and the construction of a test system (Fig. 1), resource allocation optimization in an intercloud environment, and the realization of a large-scale design optimization framework on a nationwide scale by linking supercomputers and intercloud infrastructure (Fig. 2). We are also conducting joint research with universities, research institutes and companies across the country.
Masaharu Munetomo Professor -
Accelerometer to Identify Where You Stumble
To prevent falls in elderly people
To avoid serious injuries due to falls, we studied a system that can search places with a potential danger of stumbling, which is a sign of a fall, based on people’s daily activities. The system uses an accelerometer embedded in sandals to identify the stumbling point, and an infrared sensor network on the ceiling to identify the location of the stumbling point.
Research
According to a survey by the Tokyo Fire Department in 2014, approximately 80% of all cases of emergency transportation of elderly people are due to accidents involving falls. Since their consciousness cannot keep up with their declining physical abilities, they stumble over small steps, footwear, or clothing. Much research is done on the detection of falls, but it is too late after the actual fall. Therefore, we decided to eliminate the causes of falls by detecting the areas where people often stumble. Wearable devices have problems with forgetfulness and psychological resistance to wearing it, while non-wearable devices such as surveillance cameras have problems with blind spots and privacy protection. In this study, an acceleration sensor is attached to normal sandals to detect a stumble, while a network of infrared sensors installed on the ceiling works in conjunction to identify the location of the stumble. In our experiments, we were able to distinguish falls easily, but the accuracy rate of distinguishing stumbling from normal walking is currently only about 1/4, so we hope to improve the accuracy in the future.
Mineichi Kudo Professor -
Advanced Optical Communication Technology, the Core of the Next-generation Ultrahigh-speed Communication Network
Aiming at spectacular advancement of information and communication networks
To realize spectacular advancement of information and communication networks of which the capacity has to increase by a factor of 1,000 in the next 20 years, we are working to develop photonic infrastructure technology that will be the core of next-generation ultrahigh-speed communication networks.
Research
We are studying new structured optical fibers to overcome the limitation of existing optical fibers, optical fiber application technologies to ensure safety and security, ultra-compact optical circuits to support opticalization, and optical simulators to support the design of optical fibers and optical circuits.
Kunimasa Saitoh Professor -
An Idea-supporting Multimedia Search System
An information retrieval system that organically links images, video and other data to help searchers find inspiration and ideas.
The idea-supporting multimedia search system organically links unstructured data such as images, music and video, extracts inherent similarities and effectively presents them to searchers to help them find ideas and inspiration.
Research
We have succeeded in establishing associations and similarities between different media, and developed an associative search scheme that takes ambiguity of multimedia information into consideration (fused search). We have also realized a new search engine and interface by quickly introducing modeling of personal preferences through user networks and visualization of similarities in preferences through user interfaces (personal adaptive search). Use of the search engine and interface enables a completely new search that effectively utilizes the polysemy and ambiguity inherent in multimedia contents.
Miki Haseyama Professor -
AR Communication System
Avatar-based augmented reality group communication through sharing of terminal position and posture information
By using avatars as intermediaries, it is possible to communicate beyond the constraints of time and space. In this system, AR communication is realized by sharing the position and posture information of participants in group communication and reflecting it in the behavior of avatars visible from each participant's terminal.
Research
Since conventional avatar-based communication systems are based on one-to-one communication, it is difficult to recognize the position and posture information of each physical person participating in a communication field of three or more people where virtual and real worlds are mixed, and to control the behavior of individual avatars accordingly, while maintaining the integrity of the entire field.
In this research, we have developed an AR communication system that shares the position and posture information of physical people (e.g., smartphone terminals) participating in a communication field through recognition of a common AR target and network linkage between terminals, and reflects this information in the behavior of avatars visible from each terminal. The avatars know who and where the participants are in the communication field, and the avatar changing its pose following the movements on one participant's terminal can be seen by other participants from their own viewpoints.Yoshiaki Takai Professor -
Boundary Element Analysis Framework and Distributed H-matrix Method
Realizing cutting-edge, large-scale, high-precision analysis
We have developed a software framework for high-performance boundary element analysis in a parallel computing environment. We have also developed a distributed parallel H-matrix library, which is effective to accelerate a BEM analysis, and evaluated its performance on programs in various applications.
Research
In this study, we developed a parallel boundary element analysis framework as part of the JST CREST project on “Application Development and Execution Environment with Automatic Tuning Mechanism.” By using this framework, it is possible to develop boundary element analysis programs for large-scale parallel computing systems with a small programming cost. We also developed a library of H-matrices, which approximates dense matrices with less data using low-rank approximation. This library can be used for analysis of N-body problems in addition to boundary element analysis, and is already being used for earthquake simulation on supercomputers. There is no other H-matrix library that supports hybrid parallel processing utilizing multiple threads and processes, and this is a unique feature of this research.
Takeshi Iwashita Professor -
Communication Robot System
Social space recognition system using dialogue activity and attention guidance system and multiple robots
By calculating the level of activity of a dialogue between people, a robot can recognize the intensity of that dialogue space and adapt its behavior to the context. Furthermore, by applying this mechanism to the behavior of multiple robots, it will become possible to guide the user's attention.
Research
Our dialogue activity calculation system calculates the real-time activity level using information such as the distance between the interactants, voice data, and body movements. By using this activity level, the robot can determine whether it is allowed to enter the dialogue space or interrupt the dialogue, and can take contextually adaptive actions. Furthermore, by having multiple robots act in a way that increases the dialogue activity level for each other's actions, the user's attention (e.g., gaze) can easily be guided. Such a system for generating robot behavior using the level of dialogue activity has not been included in conventional research on social robots, and can be applied to robots at reception desks and home robots for households.
Tetsuo Ono Professor -
Communication-avoidant Matrix Calculation Algorithm
Research and development of algorithms suitable for massively parallel computers
With the spread of massively parallel computers, it has become increasingly important to reduce the communication time associated with parallel computation. In this research, we aim to improve the performance of matrix computation algorithms by using an approach called “Communication Avoiding (CAA).”
Research
With parallel processing using large-scale parallel computers, the data communication time is often more important than the computation time. In particular, the large communication latency (the cost incurred regardless of the amount of data to be communicated) has become a problem, and there is a strong need to reduce the communication frequency (communication avoidance). We are reviewing existing matrix computation algorithms from the viewpoint of communication avoidance, and are researching and developing new algorithms for massively parallel computers that reduce the communication frequency.
Takeshi Fukaya Associate Professor -
Compact Aerial Video Display System
Direct Touch Visual Presentation System with which images look as if they are floating on the desktop and can be touched directly
We have developed a small video display system that displays images such as 3DCG, which are conventionally shown on a display, in the air. Users can directly reach out and touch the images that seem to float in front of them on their desktop.
Research
Improvement in the performance of stereoscopic displays and head-mounted displays (HMDs) has led to improvement in the quality of 3DCG and virtual reality (VR) experiences. With this research, we are studying the next generation of information interfaces. Aerial video display technology does not require displays, goggles, or other equipment in the space in front of the user. With the technology, 3DCG can be displayed in real space, and the user does not have to enter virtual space, thus it is possible to present information naturally, both in terms of equipment and visuals. Furthermore, the user can directly reach out to where the image is displayed, and can touch and move the image. In addition to realizing this aerial video display system in a desktop size, we are also researching the technology to create video content suitable for it.
Shunsuke Komizunai Assistant Professor -
Developing Interfaces that Read Users’ Intentions
Controlling robots and mice freely
We are developing interfaces that make it possible for users and machines to learn from each other and to operate machines as the users intend. It also facilitates the control of robots and other machines, and input with pointing devices such as mice and trackballs.
Research
For a user to operate a multi-degree-of-freedom robot such as a humanoid robot, it is necessary to remember which commands correspond to which operations, and the more commands there are, the harder it becomes for the user. Since it is usually difficult to prepare a set of commands that are easy to remember and use for all, there is no guarantee that the interface created will be easy to use. With this research, we read the user's intentions through the interaction between the user and the machine, and construct an interface that the user can operate intuitively. As a result, we can develop easy-to-use interfaces that match the characteristics of individual users. We are also applying this technology to the development of an air mouse and air trackball that can be operated without a device by sensing the movement of the hand operating the mouse or trackball.
Masahito Yamamoto Professor -
Development of a High-speed Japanese Input System for Mobile Devices
Development of a fast and easy Japanese input method for smartphones and other mobile phones
There is still no fast and easy way to input Japanese on mobile devices (smartphones, etc.). With this research, we are developing a system that halves the number of keystrokes normally required to input Japanese characters by using a powerful learning function that matches the respective lines in the Japanese syllabary with numbers.
Research
This system translates strings of numbers input by degenerated keywords into a Japanese sentence with mixed Chinese characters and Japanese phonetic characters. Through degenerated keyword input, one line in the Japanese syllabary is matched with one number to allow fast and easy input. This system provides words by using inductive learning to compare the strings of numbers and the proofread translation results. Therefore, even if the dictionary is empty, the system can generate a dictionary adapted to the target field. However, input of a sequence of numbers from degenerated vowel information may cause ambiguity. To solve this problem, this system uses information on adjacent characters, top-level words and position presumption information. The use of top-level words and position presumption processing increases the number of words acquired, and the adjacent character information enables the conversion that takes connections between words into account.
Kenji Araki Specially Appointed Professor -
Development of an Electronic Holographic HMD Device
Ideal 3D image display
We are developing a head-mounted 3D display (HMD) device using electronic holography. This is a compact, lightweight and practical device realized by using a new computational algorithm and a newly designed optical system.
Research
Electronic holography-based display devices can display stress-free 3D images that are compatible with human visual physiology. Using computational correction, the head-mounted display (HMD) developed with this research replaces the complex optical system that had been required in the past, with a simple optical system. As a result, we have achieved the smallest and lightest electronic holography system in the world at low cost. As shown in the figure below, the hologram image can also be displayed to fit in the depth.
Unlike conventional HMDs, this HMD does not cause users stress due to a shift in depth focus.Yuji Sakamoto Professor -
Development of Mathematical Algorithms for Biomedical Optical Imaging
Development of a mathematical model for light propagation model inside biological tissues
A highly accurate and computationally efficient light propagation model is necessary for the progress of biomedical optical imaging. In this study, we have succeeded in constructing a fast solution method for the radiative transfer equation that describes light propagation with high accuracy. We are working on the advancement of an optical diagnosis and treatment using the proposed method.
Research
In this study, we are constructing a mathematical algorithm for biomedical optical imaging based on the radiative transfer equation. Our goal is to develop an imaging technique with excellent image resolution that can be applied to biological tissues and body parts where conventional imaging based on mathematical models cannot be applied. Until now, the numerical computational burden of the radiative transfer equation has been enormous, limiting its applicability to small-sized organisms. In this study, we have succeeded in developing a highly accurate and computationally efficient light propagation model by coupling the radiative transfer equation and the photon diffusion equation. Optical imaging based on the developed light propagation model can be applied to various biological tissues and sites. Currently, we are working on applying the model to the optical diagnosis of thyroid tumors in the human neck and the in-vivo evaluation of optical property values in biological tissues.
Hiroyuki Hujii Assistant Professor -
Estimating the State of Radio Waves Using the Compressed Sensing Method
Toward highly accurate location estimation and channel prediction
The compressed sensing method is a method to find a solution under certain conditions from a smaller number of observation data than the number of unknowns required. In this study, we use compressed sensing for estimating the direction of arrival of radio waves, to predict the channel, and detect scatterers.
Research
It is usually impossible to specify unknowns if their number among observation data is smaller than the number of unknowns that need to be found. However, in case the majority of unknowns are zero, it is sometimes possible to obtain the exact solution. Compressed sensing is a method for obtaining an accurate solution while minimizing the number of observations by using this property. In our laboratory, we are investigating the application of this method to high-precision estimation of the direction of arrival of radio waves as shown in Fig. 1, a method of channel prediction by dividing the incoming wave into elementary waves using this method (Fig. 2), and scatterer detection using the compressed sensing used in radar systems (Fig. 3).
Toshihiko Nishimura Professor -
Event Information Recommendation System
A system that collects data from a few weeks before an event to the day of the event and recommends appropriate event information.
Although event information was only valid for a short time and it was hard to handle it with conventional information recommendation technology, we have developed a flexible recommendation method by combining multiple factors such as user interest and geographic characteristics.
Research
The system estimates the genres and information sources that a user prefers based on the user’s past information browsing history, and assesses the event information that the target user is interested in by referring to the browsing trends of users with similar interests. It also takes into account the geographic characteristics of the user and finally presents the information to him/her. The timing of information distribution is adjusted throughout the system so that the overall system performance can be improved.
Hidenori Kawamura Professor -
High Value-added Media Information and Communication Technology
High value-added media information and communication technology using sub-channel data communication with information hiding technology
We are researching high value-added media information and communication technology that can add new functions while maintaining compatibility with standard formats, by using information hiding technology that is usually used as an information security method.
Research
This research is aimed to add value to media information and communication technology using sub-channel data communication with information hiding technology.
As an application example, this study investigates high-fidelity sound of the voice on the telephone. With the proposed method, information for widening the bandwidth is embedded in the voice data in advance at the transmitter side, so that the voice can have high-fidelity on the receiver side.
This research also investigates a method for detecting tampering by embedding information that can guarantee the originality by image data. Figures 1 to 3 show an example of the proposed method for detecting tampering with a car license plate. When an image is tampered with, the corresponding part of the image is revealed, and the proposed method will not only detect the tampering, but also the tampered part.Naofumi Aoki Assistant Professor -
High-precision Acoustic Position Recognition, Time Synchronization, Selective Flickerless Visible Light Communication
Submillimeter-order position measurement and its deployment
By integrating ranging technology that is more accurate than conventional methods by double digits and original time-synchronization technology using illumination, we can quickly and accurately estimate the 3D position and velocity of mobile terminals and robots. The system also realizes selective flickerless visible light communication and position-dependent information distribution to specific moving objects.
Research
To accurately obtain the position of a user in a room or a moving object in real time, we have proposed a high-precision time reference point setting method called the phase-matching method (ranging error of 0.03 mm). Based on this technology, we have developed a smartphone users’ gesture recognition system and a robot tracking system. We have also achieved microsecond-order time synchronization using a camera-equipped mobile terminal and an original algorithm. The integration of LED modulation and terminal location information will allow us to distribute location-dependent information and conduct flickerless visible light communication using indoor lighting.
Masanori Sugimoto Professor -
Low-power A/D Converters for Sensing
Use of time to digital converter for A/D converter and its low power consumption
Single-Slope A/D converters, which involve the simplest configuration, are used in various forms (image sensors, etc.). However, one drawback is their slow conversion speed. With this technique high speed and low power consumption can be achieved simultaneously.
Research
Single-Slope A/D converters convert analog values to time and then digitize them. By using the Time to Digital Converter (TDC), the conversion time can be greatly reduced. However, power consumption increases significantly. Intermittent operation of the TDC is effective to reduce the power consumption of the TDC part by a factor of several times ten, enabling both high speed and low power consumption. The features of this method are as follows:
Realization of low-power, high-speed, small-area A/D converters
・Synchronization and consistency of two measurements with high precision and coarse accuracy are guaranteed in principle
・The A/D conversion characteristics are continuous and easy to correct.Masayuki Ikebe Professor -
Mathematical Analysis Techniques for Information Science and Engineering
System identification, design and inverse problems
Exploration of methodologies and development of applied technologies to solve problems in information science and engineering related to system identification and design and estimation of unknown objects
Research
In the field of information science and engineering, many problems appear, such as the problem of designing a mathematical system that provides a desired result, the problem of identifying a mathematical model that gives a given input and output, and the inverse problem of estimating unknown inputs from a system and observations. When dealing with these problems, by dividing the analysis into conditions specific to each problem and mathematical models independent of each problem, it becomes possible to theoretically determine the performance and limitations, and to also expand the analysis horizontally to problems that can be described by similar mathematical models. With this unique approach, we have developed various methodological constructs and application techniques in machine learning problems including image and color restoration, separation of individual sounds in acoustic signals, pattern recognition, and sampling theory. By applying our methodology to today's rapidly developing and diverse measurement technologies, we expect to develop a variety of application techniques based on theory.
Akira Tanaka Professor -
Multimedia Artificial Intelligence Technology Reaching Social Implementation
Approaching the practical application of AI technology through industry-university collaborative research!
With this research, we are developing artificial intelligence technology for multimedia data, mainly images, video, music, and audio. We are handling data related to medical images, social infrastructure data, materials science and other fields, mainly through industry-university collaborative research.
Research
We are not only conducting the world's most advanced artificial intelligence research, but also promoting research in interdisciplinary areas and taking on the challenge of solving real-world problems. Specifically, in medical imaging research, we have collaborated with many medical institutions in Japan to build AI technology that surpasses human diagnostic accuracy. In medical and civil engineering research, we have built Explainable AI (XAI), which not only enables learning of small amounts of data, a challenge in AI research, but also enables explanations of judgment results, making the technology usable in the real world. In recent years, we have also developed human-centric AI technology that can make decisions like humans by introducing information strongly related to human interests, such as human brain activity and eye gaze data, into the AI learning process.
Takahiro Ogawa Professor -
Next-generation Visualization Technology for Sports Content
Creation of information presentation technology that accelerates knowledge sharing
We are building next-generation visualization technology to provide data that support sports watching and education. Using various data obtained from users and their surrounding environment, we will derive a theory that defines, “analysis data” and “presentation methods adapted to the usage environment” to enable information presentation that accelerates knowledge sharing.
Research
In terms of the present situation concerning sports, various forms of image and video distribution have spread, and a new environment for watching sports is being established, whereby related data along with images and video footing can be viewed via smartphones and other mobile terminals. However, with soccer, it is only possible to view basic data such as free kick success rate and running distance. This research analyzes various data obtained from users and their surrounding environment to help them understand and visualize the data to accelerate knowledge sharing, even when the relevant knowledge and experience are essential. Examples include ball passing and the degree of dominance. Since the visualization technology of this research can obtain various data surrounding the user and provide various kinds of information in a way that is adaptable to the user's environment, it has high potential for application to the fields of IoT and AI, and is expected to contribute to the creation of new technologies in these fields.
Sho Takahashi Associate Professor -
Optical Complex Amplitude Measurement Technology
Enabling the detection of spatial phase information of light: Technology for seeing the invisible
This technology enables precise detection of optical phase distribution in a single measurement without spatial completion error by using two sensors and a polarizing optical element, and is expected to have a wide range of applications such as 3D image measurement, 3D tomography, digital phase conjugation, 3D optical memory, and spatial mode optical communication.
Research
In holographic diversity interferometry, multiple image sensors are arranged in combination with a polarizing optical element to enable precise detection of optical phase distribution in a single measurement without spatial completion error. We have developed an interferometric optical system using two image sensors and have greatly improved the measurement algorithm to achieve highly accurate phase measurement and enable 3D information processing using the measured phase distribution data. This technology can be applied directly to the acquisition of 3D optical information, optical tomography by digital phase conjugation, and 3D optical memory. In this research, we have also succeeded in developing a reference light-free phase detection system that filters the signal light spatially filtered and re-interacts with the signal light. This is expected to find applications in next-generation ultrahigh-speed optical communication systems using spatial modes and in the field of remote sensing.
Atsushi Okamoto Associate Professor -
Quality Control in Crowdsourcing
Highly accurate decision-making using people’s confidence rating
We are conducting research to guarantee the quality of work results in crowdsourcing, which allows us to commission jobs to many people via the Internet. The use of workers’ confidence rating on the work results will be effective to ensure high-quality work results.
Research
With the advent of crowdsourcing services in recent years, it has become easy to commission jobs (tasks) to a large number of people via the Internet, and these services are being used in various fields of information science (image recognition, natural language processing, information retrieval, databases, etc.). In crowdsourcing, it is important to check the work quality because not all workers necessarily have the required skills and diligence to work on a task. We have proposed a method to ensure the work quality by asking workers to report their confidence (degree of conviction) in their work results. The technical feature of this method is that it does not trust the confidence rating reported by workers as it is, but performs statistical quality control assuming the existence of over- and under-confident workers.
Satoshi Oyama Associate Professor -
Real-time Video Processing Technology
Algorithm development and its hardware implementation
In this laboratory, we are promoting research and development of various image processing algorithms and their real-time implementation, focusing mainly on image smoothing and brightness correction of video images, which are recently increasing in capacity (high resolution and high frame rate).
Research
Since the amount of data handled during image processing is generally huge, it is essential to optimize the system as a whole by combining hardware and software. In this laboratory, we are investigating the configuration of image processing systems by studying image processing algorithms and their implementations complementarily. One of the results of our research is real-time adaptive brightness correction of video images based on the Retinex theory (Fig. 1), which can adaptively correct the brightness of video images taken under conditions of large changes in illumination, such as backlighting, in real time. We are also working on high-quality image smoothing (Fig. 2) based on cost optimization, which is expected to be applied to image processing such as photo illustration, pre-processing of various image processes, brightness correction, and detail enhancement.
Hiroshi Tsutsui Associate Professor -
Recognition and Modeling Technology for Laser Scanned Point Clouds
Toward more sophisticated analysis, maintenance and management, and planning of environments and structures where human activity takes place
We are developing theories and algorithms for point cloud processing to automatically recognize and create 3D models of objects and structures that exist in environments where human activity takes place, such as rooms, roads, pole-like objects (utility poles and street lights), street trees, and buildings, from 3D laser scanned point clouds.
Research
We are researching technologies for the automatic recognition and modeling of objects and structures in indoor and outdoor environments from point clouds obtained by ground-based and vehicle-mounted 3D laser scanning systems, as well as basic point cloud data processing methods. The objects to be recognized and modeled include a wide range of arbitrarily shaped objects, rooms, pole-like objects such as utility poles and street lights, trees, road surfaces, and buildings. In addition to the technology of generating mesh models, polygon models, and CAD models from point clouds, we also conduct research on point cloud registration, segmentation, shape feature extraction, machine learning, and procedural object recognition that serves as the foundation for the technology. This technology enables detailed recognition and analysis of the environment and structures, maintenance and management, various simulations and improvement plans using 3D models that faithfully reflect the current state.
Hiroaki Date Associate Professor -
Recommendation Techniques Using the Bandit Method
Online learning technology that maximizes cumulative gain while acquiring knowledge
We are researching a recommendation method that maximizes the user's cumulative satisfaction, not only by recommending items that the user may prefer (use of knowledge), but also items that may provide more information about the user's preferences (acquisition of knowledge) in a balanced manner.
Research
In today's internet society, recommendation technology, if it works well, can benefit both the provider and the receiver of the service. A recommendation service is not a one-time event, but an iterative process with feedback each time, and the feedback only concerns the items that are recommended. Therefore, to increase the accuracy of subsequent recommendations, it is not only important to recommend items that the user is likely to like based on the feedback history (knowledge utilization), but also items from which the user is likely to acquire more information (knowledge acquisition). The Bandit method attempts to maximize user satisfaction by balancing the use and acquisition of knowledge. We are developing a recommendation system using this method.
Atsuyoshi Nakamura Professor -
Security Certification Technology for Quantum Key Distribution Devices
Experimental certification of ultimate cryptographic security
Using quantum key distribution, we can share cryptographic keys via optical communication while maintaining a high level of secrecy, no matter how the technology advances in the future. Through our research, we offer technologies to experimentally guarantee the security of quantum cryptography using an actual device to realize its practical application.
Research
The quantum key distribution technology has passed the proof‐of‐principle phase, and research is now under way with an eye on its practical application. Since this is a technology to realize the ultimate confidential communication, field tests and other researches on it are conducted worldwide. In our laboratory, we are examining both theoretical and implementation-related aspects on quantum key distribution. In the real world, things do not always go according to the theory, and experimental results sometimes differ from those expected in theory. Our goal is to examine these discrepancies and quantitatively guarantee the security of cryptographic keys produced on real devices. To this end, we are conducting research to fill the gap between the theoretical studies and the actual device development. We believe that this research will open the way to measure and evaluate the behaviors of the actual quantum devices, and finally to realize practical quantum systems, which will contribute to future quantum networks.
Akihisa Tomita Professor -
Simultaneous Observation of Electrical Properties and Structural Changes Using an Electron Microscope
The relationships between electrical properties and structural changes can be evaluated and validated
An electronic device fragment is placed in the electron microscope, and a movable probe electrode is applied to it, enabling observation by the electron microscope while evaluating its electrical characteristics. A MOSFET is connected to the sample side electrode to suppress excessive current. It allows evaluation of the correlation between electrical characteristics and structural changes and is useful to investigate the cause of failures.
Research
Our in-situ electron microscopy system is capable of three-terminal device measurements using two movable probes and a fixed sample holder as electrodes. A MOS transistor is inserted in the sample holder to limit the excess current flow due to stray capacitance.
Microelectronic devices that are almost ready for practical application include devices such as phase-change memory and resistance change memory that can predict structural changes accompanying resistance changes. It is difficult to confirm the mechanism of resistance changes in microdevices due to their high operating speed and nanoscale structure, but this system enables the evaluation of such a mechanism and helps to efficiently investigate the cause of the defective operation and ensure its reliability. By using this system, we can also effectively confirm the operating functions and evaluate the causes of defects in nanostructured functional devices, such as nanomachines and nanostructured secondary batteries, which are expected to be further developed in the future. -
Soft Error Testing of Telecommunication Equipment Using a Compact Electron Accelerator Neutron Source
Preventing malfunctioning of telecommunication devices caused by cosmic rays
As the semiconductor devices of equipment that support telecommunication networks are becoming more intensively integrated, there is concern that the probability of soft errors caused by cosmic-ray neutrons will increase. To address this problem, we are conducting soft error tests of telecommunication devices using a compact accelerator-driven neutron source at Hokkaido University.
Research
As telecommunication devices increase in capacity and become more sophisticated, semiconductor devices are becoming more and more integrated. However, there is concern that cosmic ray neutrons may cause an increase in soft errors, such as bit information upset and operation confusion. Therefore, in collaboration with NTT, we have reproduced soft errors using a compact electron accelerator-driven neutron source to create a place to develop countermeasure technologies in advance. This enables the advance prediction of the failure rate in the natural environment, the detection of errors and verification of operational measures, which will lead to improved reliability of the equipment.
The feature of this technology is the use of a compact accelerator-driven neutron source. In the past, large-scale accelerator-based neutron sources were required, and it was difficult to secure sufficient test time and experimental space. However, through our research, we have demonstrated that it is possible to conduct sufficient tests even in a facility with a neutron intensity of several million times that in nature.Hirotaka Sato Associate Professor -
Spatio-temporal Control of Laguerre-Gaussian Light
Information multiplexing using the spatial phase of light
In this study, we have developed a fundamental technology for information multiplexing using Laguerre-Gaussian (LG) light, which has a characteristic spatial phase. By focusing on the spatial phase, which has not been actively used in conventional optical information processing, we aim to increase the information capacity.
Research
Optical information processing, transmission, recording and reproduction are performed using the intensity, polarization and spatially uniform phase of laser light. The transmission capacity can be increased through multiplexing using different frequencies. In contrast, the spatial characteristics of light form an unexplored area that has not been actively utilized until now. Based on this background, information multiplexing using Laguerre-Gaussian (LG) light and quantum information processing using the orbital angular momentum (topological charge) that characterizes LG light have been attracting attention as a step to overcome the limitation of information processing capacity. In this study, we have utilized material interaction and realized the mode control of LG light and the conversion and conservation of orbital angular momentum using short-pulsed light, as well as space-division multiplexing fiber transmission.
Yasunori Toda Professor -
System Control Technology Based on Mathematical Methods
From mechanical to energy management systems
System control technology based on mathematical models can be applied to a wide range of fields, from mechanical systems such as four-wheeled robots to social systems such as energy management systems. At this laboratory, we are developing control methods for nonlinear and hybrid systems in particular.
Research
Many systems, such as manipulators and automobile engines, are nonlinear systems. Many conventional methods are created in view of individual cases. In this laboratory, we are developing a unified control method using control Lyapunov functions. As an example, we are considering the development of a four-wheeled robot running on a flat surface (Fig. 1). To achieve obstacle avoidance and movement to the target position, a pseudo height difference is set (Fig. 2). The obstacles are positioned high and the target is positioned low. This allows four-wheeled robots to achieve their control objectives with only one simple rule of following the low position.
Dynamical systems that include switching of dynamics are called hybrid systems, and are known to have many applications. Recently, we have been working on the application of hybrid systems to energy management systems. In particular, we are developing an electricity consumption model for consumers.Yuh Yamashita Professor -
Time-resolved Two-dimensional Surface Acoustic Wave Imaging
Excitation and detection of arbitrary frequency response by optical pulse train with fixed period
This technique visualizes the propagation of surface acoustic waves up to the GHz frequency range as a time-resolved two-dimensional image. Conventional methods involve the problem of low frequency resolution, but this method can excite and detect acoustic waves of any frequency.
Research
Visualization of acoustic wave propagation is extremely useful in the evaluation of physical properties and the design, fabrication and evaluation of functional devices using acoustic waves. For this purpose, we excite surface acoustic waves by irradiating the sample with an ultrashort optical pulse of subpicosecond duration (pump light), and observe their propagation with delayed optical pulse (probe light). Time-resolved two-dimensional images of the acoustic waves are obtained by scanning the delay time and the irradiation position of the probe light. The time resolution is in picoseconds, the spatial resolution is 1μm, and the frequency range is in GHz. Since this method uses a periodic optical pulse train, it was previously only possible to excite and detect acoustic waves at integer multiples of the repetition rate. However, with the newly developed technique, we have realized the excitation and detection of acoustic waves of any frequency. By developing this technique, we have also achieved image vibrations that are completely asynchronous to the repetition frequency of the optical pulse, thereby expanding the range of applications.
Osamu Matsuda Professor -
Vertical Takeoff and Landing Type Unmanned Aerial Vehicle
An unmanned aircraft that can fly at high speed like an airplane and hover in midair like a helicopter
We have developed a vertical takeoff and landing type unmanned aerial vehicle that can hover like a helicopter while flying at high speed by obtaining lift with its wings like an airplane. It is expected to be used, for example, to quickly fly to a stricken area in the event of a disaster and to photograph the area while hovering in the sky.
Research
There are expectations of the industrial application of unmanned aerial vehicles, as DHL and Amazon are performing tests on delivery by unmanned aircraft. These unmanned aircraft are helicopter-type vehicles called multicopters. Since they have fixed wings and fly like airplanes, they move efficiently and at a high speed, and can fly farther than ordinary multicopters with the same battery.
Atsushi Konno Professor -
Visual Expression by Computer Graphics
Supporting intellectual and creative activities with computers
We aim to support people’s creative activities using 3D computer graphics. Despite significant development of computer graphics, it is not easy to manipulate 3D information, and we are not yet ready to use this information to support our creative activities. We are exploring a mechanism to freely manipulate information in 3D space and easily create CG images.
Research
To produce images using CG, we have to prepare a huge number of parameters related to shape, camera, lighting, material, etc. To achieve the desired result, these parameters must also be adjusted by trial and error. An extended calculation time is also required to create precise images. This makes it impossible to conduct creative activities using CG. Therefore, we are developing a method to solve these problems. For parameter adjustment, we have introduced the inverse problem approach, and for computation time, we are developing a fast computation method using parallel computation. We are also applying these ideas to digital fabrication using 3D printers. We are also working on the development of a new user interface to reflect the user’s intentions more intuitively.
Yoshinori Dobashi Professor
