Hiroshima City University

Hossain M.D., Inoue H., Ochiai H., Fall D., Kadobayashi Y.

The modern automobile is a complex piece of technology that uses the Controller Area Network (CAN) bus system as a central system for managing the communication between the electronic control units (ECUs). Despite its central importance, the CAN bus system does not support authentication and authorization mechanisms, i.e., CAN messages are broadcast without basic security features. As a result, it is easy for attackers to launch attacks at the CAN bus network system. Attackers can compromise the CAN bus system in several ways including Denial of Service (DoS), Fuzzing and Spoofing attacks. It is imperative to devise methodologies to protect modern cars against the aforementioned attacks. In this paper, we propose a Long Short-Term Memory (LSTM)-based Intrusion Detection System (IDS) to detect and mitigate the CAN bus network attacks. We generate our own dataset by first extracting attack-free data from our experimental car and by injecting attacks into the latter and collecting the dataset. We use the dataset for testing and training our model. With our selected hyper-parameter values, our results demonstrate that our classifier is efficient in detecting the CAN bus network attacks, we achieved an overall detection accuracy of 99.995%. We also compare the proposed LSTM method with the Survival Analysis for automobile IDS dataset which is developed by the Hacking and Countermeasure Research Lab, Korea. Our proposed LSTM model achieves a higher detection rate than the Survival Analysis method.

Goto M., Abe O., Hagiwara A., Fujita S., Kamagata K., Hori M., Aoki S., Osada T., Konishi S., Masutani Y., Sakamoto H., Sakano Y., Kyogoku S., Daida H.

Surface-based morphometry (SBM) is extremely useful for estimating the indices of cortical morphology, such as volume, thickness, area, and gyrification, whereas voxel-based morphometry (VBM) is a typical method of gray matter (GM) volumetry that includes cortex measurement. In cases where SBM is used to estimate cortical morphology, it remains controversial as to whether VBM should be used in addition to estimate GM volume. Therefore, this review has two main goals. First, we summarize the differences between the two methods regarding preprocessing, statistical analysis, and reliability. Second, we review studies that estimate cortical morphological changes using VBM and/or SBM and discuss whether using VBM in conjunction with SBM produces additional values. We found cases in which detection of morphological change in either VBM or SBM was superior, and others that showed equivalent performance between the two methods. Therefore, we concluded that using VBM and SBM together can help researchers and clinicians obtain a better understanding of normal neurobiological processes of the brain. Moreover, the use of both methods may improve the accuracy of the detection of morphological changes when comparing the data of patients and controls.

Xu C., Ishikawa N., Rajashekar R., Sugiura S., Maunder R.G., Wang Z., Yang L., Hanzo L.

Sixty years of coherent versus non-coherent tradeoff as well as the twenty years of coherent versus non-coherent tradeoff in Multiple-Input Multiple-Output (MIMO) systems are surveyed. Furthermore, the advantages of adaptivity are discussed. More explicitly, in order to support the diverse communication requirements of different applications in a unified platform, the 5G New Radio (NR) offers unprecendented adaptivity, abeit at the cost of a substantial amount of signalling overhead that consumes both power and the valuable spectral resources. Striking a beneficial coherent versus non-coherent tradeoff is capable of reducing the pilot overheads of channel estimation, whilst relying on low-complexity detectors, especially in high-mobility scenarios. Furthermore, since energy-efficiency is of salient importance both in the operational and future networks, following the powerful Index Modulation (IM) pholosophy, we conceive a holistic adaptive pholosophy striking the most appropriate coherent/non-coherent, single-/multiple-antenna and diversity/multiplexing tradeoffs, where the number of RF chains, the Peak-to-Average Power Ratio (PAPR) of signal transmission and the maximum amount of interference tolerated by signal detection are all taken into account. We demonstrate that this intelligent tripple-fold adaptivity offers significant benefits in next-generation applications of mmWave and Terahertz solutions, in space-air-ground integrated networks, in full-duplex techniques and in other sophisticated channel coding assisted system designs, where powerful machine learning algorithms are expected to make autonomous decisions concerning the best mode of operation with minimal human intervention.

Belz J.W., Krehbiel P.R., Remington J., Stanley M.A., Abbasi R.U., LeVon R., Rison W., Rodeheffer D., Abu‐Zayyad T., Allen M., Barcikowski E., Bergman D.R., Blake S.A., Byrne M., Cady R., et. al.

In this paper we report the first close, high-resolution observations of downward-directed terrestrial gamma-ray flashes (TGFs) detected by the large-area Telescope Array cosmic ray observatory, obtained in conjunction with broadband VHF interferometer and fast electric field change measurements of the parent discharge. The results show that the TGFs occur during strong initial breakdown pulses (IBPs) in the first few milliseconds of negative cloud-to-ground and low-altitude intracloud flashes, and that the IBPs are produced by a newly-identified streamer-based discharge process called fast negative breakdown. The observations indicate the relativistic runaway electron avalanches (RREAs) responsible for producing the TGFs are initiated by embedded spark-like transient conducting events (TCEs) within the fast streamer system, and potentially also by individual fast streamers themselves. The TCEs are inferred to be the cause of impulsive sub-pulses that are characteristic features of classic IBP sferics. Additional development of the avalanches would be facilitated by the enhanced electric field ahead of the advancing front of the fast negative breakdown. In addition to showing the nature of IBPs and their enigmatic sub-pulses, the observations also provide a possible explanation for the unsolved question of how the streamer to leader transition occurs during the initial negative breakdown, namely as a result of strong currents flowing in the final stage of successive IBPs, extending backward through both the IBP itself and the negative streamer breakdown preceding the IBP.

Shan Y., Li S., Chen T.

Psychological stress may cause various health problems. To prevent the potential chronic illness that long-term psychological stress could cause, it is important to detect and monitor the psychological stress at its initial stage. In this paper, we present a framework for remotely detecting and classifying human stress by using a KINECT sensor that is portable and affordable enough for ordinary users in everyday life. Unlike most of emotion recognition tasks in which respiratory signals (RSPS) are usually used only as an aiding analysis, the whole task proposed is based on RSPS. Thus, the main contribution of this paper is that not only the non-contact devices is used to identify human stress, but also the relationship between RSPS and stress recognition is analyzed in detail. Experimental results on 84 volunteers show that the recognition accuracy for recognizing psychological stress, physical stress, and relaxing state are 93.90%, 93.40%, and 89.05% respectively. These results suggest that the proposed framework is effective for monitoring human stress, and RSPS could be used for stress recognition.

Kimura K., Yamamoto K., Hayashi K., Tsutsui S., Happo N., Yamazoe S., Miyazaki H., Nakagami S., Stellhorn J.R., Hosokawa S., Matsushita T., Tajiri H., Ang A.K., Nishino Y.

X-ray absorption fine structure (XAFS), x-ray fluorescence holography (XFH), and inelastic x-ray scattering (IXS) techniques were applied to an ${\mathrm{Fe}}_{2}({\mathrm{V}}_{0.95}{\mathrm{Ta}}_{0.05}$)Al Heusler-type thermoelectric material to investigate the doping effect of Ta on the local structure and the atomic dynamics. The XAFS and XFH results show that the positional correlation between Ta and surrounding Fe atoms is much more rigid than that between V and Fe. In the IXS results, we observed a broad dispersionless mode in the energy range of the acoustic phonons of undoped ${\mathrm{Fe}}_{2}\mathrm{VAl}$, which is regarded as the so-called resonant mode. These results revealed a clearly different feature of the dynamics of heavy dopants from that of the matrix element, which disturbs the coherency of phonons and should contribute to the enhancement of the thermal insulation.

Nomura T., Kimura T., Kanematsu Y., Yamada D., Yamashita K., Hirata K., Ueno G., Murakami H., Hisano T., Yamagiwa R., Takeda H., Gopalasingam C., Kousaka R., Yanagisawa S., Shoji O., et. al.

Significance The short-lived intermediate formed during the reduction of nitric oxide (NO) to nitrous oxide (N 2 O) in denitrification, microbial anaerobic respiration, is a key state for understanding the generation mechanism of N 2 O, known not only as a greenhouse gas but also as an ozone-depleting substance on the global level. This paper combined state-of-the-art, time-resolved techniques, such as flow-flash infrared spectroscopy and X-ray free electron laser-based crystallography, and captured the intermediate of a P450-type NO reductase at the atomic and electronic levels. The intermediate was identified as a singly protonated Fe 3+ –NHO •− radical, offering insights into a radical–radical coupling mechanism for the N–N bond formation in N 2 O generation.

Ohira S., Desta A.K., Arai I., Inoue H., Fujikawa K.

Controller Area Network (CAN) is a de facto standard of in-vehicle networks. Since CAN employs broadcast communication and a slower network than other general networks (e.g. Ethernet, IEEE802.11), it is inherently vulnerable to Denial-of-Service (DoS) attacks. As a countermeasure against DoS attacks on CAN, a method for detecting a DoS attack using the entropy in a sliding window has been proposed. This method has a good advantage in terms of effectiveness and the small computational overhead. However, this method may only be effective against DoS attacks under naive conditions such as some higher priority messages. In addition, if an adversary can adjust the entropy of the DoS attack to its normal value, the conventional method cannot detect a DoS attack in which the adversary manipulates the entropy. We found this type of DoS attack, which is called an entropy-manipulated attack. In this paper, we propose a method that can detect an entropy-manipulated attack by using the similarity of two sliding windows. We confirmed that the proposed method detected the DoS attack in 100% of the cases in our experiment, and we showed that the detection time is up to 93% (14 μs) shorter than the conventional method.

Saito T., Takano Y.

Urease catalyzes the hydrolysis of urea to form ammonia and carbamate, inducing an overall pH increase that affects both human health and agriculture. Inhibition, mutagenesis, and kinetic studies have provided insights into its enzymatic role, but there have been debates on the substrate binding mode as well as the reaction mechanism. In the present study, we report quatum mechanics-only (QM-only) and quantum mechanics/molecular mechanics molecular dynamics (QM/MM MD) calculations on urease that mainly investigate the binding mode of urea and the mechanism of the urease-catalyzed hydrolysis reaction. Comparison between the experimental data and our QM(GFN2-xTB)/MM metadynamics results demonstrates that urea hydrolysis via a complex with bidentate-bound urea is much more favorable than via that with monodentate-bound urea for both nucleophilic attack and the subsequent proton transfer steps. We also indicate that the bidentate coordination of urea fits the active site with a closed conformation of the mobile flap and can facilitate the stabilization of transition states and intermediates by forming multiple hydrogen bonds with certain active site residues.

Fujiwara T., Sasahara A., Happo N., Kimura K., Hayashi K., Onishi H.

Alkali tantalates, NaTaO3 and KTaO3, are known as highly efficient semiconductor photocatalysts for the overall water-splitting reaction when properly doped with foreign metal cations. Characterizi...