Driver drowsiness detection (DDD) prevents road accidents caused by driver fatigue. Vehicle dynamics-based DDD has been proposed as a method that is both economical and high performance. However, there are concerns about the reliability of performance metrics and the reproducibility of many of the existing methods. For instance, some previous studies seem to have a data leakage issue among training and test datasets, and many do not openly provide the datasets they used. To this end, this paper aims to compare the performance of representative vehicle dynamics-based DDD methods under a transparent and fair framework that uses a public dataset. We first develop a framework for extracting features from an open dataset by Aygun et al. and performing DDD with lightweight ML models; the framework is carefully designed to support a variety of configurations. Second, we implement three existing representative methods and a concise random forest (RF)-based method in the framework. Finally, we report the results of experiments to verify the reproducibility and clarify the performance of DDD based on common metrics. Among the evaluated methods, the RF-based method achieved the highest accuracy of 88 %. Our findings imply the issues inherent in DDD methods developed in a non-standard manner, and demonstrate a high performance method implemented appropriately.

Cell-free multiple-input multiple-output (MIMO) is a promising distributed network architecture for 5G-and-beyond systems. This paper proposes an access point (AP) selection method that is specific to each user equipment (UE) in downlink cell-free MIMO. The APs are distributed throughout the system coverage area and know only a part of the instantaneous channel state information (CSI). As a beamforming (BF) method based on partial CSI, we use a layered partially non-orthogonal zero-forcing (ZF) method based on channel matrix muting, which is applicable to the case where different transmitting AP groups are selected for each UE under partial CSI conditions. The proposed clustering method initializes the transmitting AP group for each UE based on the conventional signal-to-leakage-and-noise-ratio based method and then updates them for all UEs in an iterative process based on the throughput considering the interference among the UEs. We show that the proposed method achieves higher average and worst-user throughput than those for conventional methods while minimizing the excessive increase in the number of transmitting APs per UE.

Simulink is a popular tool for modeling cyber-physical systems. As more models are produced in industry, automated quality assurance of models becomes increasingly important. This paper describes an empirical evaluation of four methods for the coverage testing of Simulink models: A) SimuLink Design Verifier (SLDV), a dedicated official tool; B) Template-Based Monte-Carlo (TBMC) method, a random test generation method that utilizes input signal templates; C) SMT- Based Model Checking (SBMC) method that conducts static analysis via encoding models into logic formulas; and D) a hybrid method of B and C. Based on the evaluation results, we carefully designed the hybrid method to complement the features of TBMC and SBMC. In the experiments, we have applied the methods to fourteen models and evaluated their performance. The results show that the hybrid method achieved better results than SLDV for several models.

One of the effective model checking methods is to utilize the efficient decision procedure of SAT (or SMT) solvers. In a SAT-based model checking, a system and its property are encoded into a set of logic formulas and the safety is checked based on the satisfiability of the formulas. As the encoding methods are improved and crafted (e.g., k -induction and IC3/PDR), verifying their correctness becomes more important. This research aims at a formal verification of the SMC methods using the Coq proof assistant. Our contributions are twofold: (1) We specify the basic encoding methods, k -induction and (a simplified version of) IC3/PDR in Coq as a set of simple and modular encoding predicates. (2) We provide a formal proof of the soundness of the encoding methods based on our formalized lemmas on state sequences and paths. The specification of the SMC methods and the soundness proofs are available at https://github.com/dsksh/coq-smc/.

MATLAB/Simulink is the de facto standard tool for the model-based development (MBD) of control software for automotive systems. A model developed in MBD is called a Simulink model and, for real automotive systems, involves complex computation as well as tens of thousands of blocks. In this paper, we propose an automated test generation tool for such large and complex Simulink models. The tool provides functions for (1) automatically generating high-coverage test-suites for practical models, which cannot be handled by Simulink Design Verifier (SLDV), and (2) measuring decision, condition and MC/DC coverage much more efficiently than Simulink Coverage (SLC). This automatic test-suite generation adopts a Monte-Carlo method with templates of test cases. Our experimental evaluation shows that the tool can provide test suites against practical implementation models with higher coverage and shorter execution times than SLDV.

This research proposes a novel method to present "thumbnails" of episodes of digitized comics, in order to improve the efficiency of comic search. Comic episode thumbnails are generated based on image analysis technologies developed especially for comic images. Namely, the following procedures are developed for our system: automatic comic frame segmentation, text balloon extraction, and a linear regression based model to calculate the importance score of each extracted frame. The system then selects frames from each episode with high importance score, and aligns the selected frames to create the episode thumbnail, which is presented to the system user as a compact preview of the episode. User experiments conducted with actual Japanese comic images prove that the proposed method significantly decreases the time necessary to search for specific episodes from a large scaled comic data collection.

We propose a new efficient singlecast / multicast method for active optical access network using PLZT 10 nsec high-speed optical switches. The Active Optical Network, called ActiON, has been proposed using slot type switched optical network. Compared with Passive Optical Network (PON), ActiON can quadruplicate the number of subscribers (128 users) per OLT and double the maximum transmission distance (40 km) between OLT and ONUs. However, ActiON uses slot based switching method, so it is difficult to realize the multicast delivery. In this paper, we propose the efficient singlecast / multicast method for ActiON by using PLZT optical switch elements which are controlled as “distribution mode” like an optical splitter by applying mid-control voltage. In addition, a new efficient multicast slot allocation method is proposed and formulated as a linear programming problem. This formula develops the maximum number of users which is able to be connected by multicast and the minimum number of slots is used for multicast users.

A deadline-aware scheduling scheme for the lambda grid system is proposed to support a huge computer grid system based on an advanced photonic network technology. The assignment of wavelengths to jobs in order to efficiently carry various services is critical in lambda grid networks. Such services have different requirements such as the job completion deadlines and wavelength assignment must consider the job deadlines. The conventional job scheduling approach assigns a lot of time-slots to a call within a short period in order to finish the job as quickly as possible. This raises the blocking probability of short deadline calls. Our proposal assigns wavelengths in lambda grid networks so as to meet QoS (quality of service) guarantees. The proposed scheme assigns time-slots to a call over time according to its deadline, which allows it to increase the system performance in handling short deadline calls, for example, lowering their blocking probability. Computer simulations show that the proposed scheme can reduce the blocking probability by a factor of 100 compared with the conventional scheme under the low load condition in which the ratio of long deadline calls is high. The proposed scheduling scheme can realize more efficient lambda grid networks.