研究者業績
基本情報
- 所属
- 上智大学 理工学部情報理工学科 教授
- 学位
- 博士(工学)(上智大学)
- 研究者番号
- 90407338
- J-GLOBAL ID
- 201301073146868965
- researchmap会員ID
- 7000004362
- 外部リンク
研究分野
1論文
152-
Computer Networks 288 112670-112670 2026年10月
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Zorig Melong | A Technical Journal of Science, Engineering and Technology 9(1) 165-173 2026年8月18日
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Drones 10(8) 616-616 2026年8月12日The Traveling Salesman Problem (TSP) and the Vehicle Routing Problem (VRP) are two classical combinatorial optimization problems. In recent years, their drone-assisted variants, the Traveling Salesman Problem with Drones (TSP-D) and the Vehicle Routing Problem with Drones (VRP-D) have attracted growing attention. Generally, these problems are solved using exact algorithms or metaheuristic algorithms. However, as the problem complexity increases and the scale of instances grows, these approaches often become less efficient. In this paper, we propose a reinforcement learning method with a shared attention encoder and a hierarchical dual-decoder architecture, where truck–drone coordination is achieved by first decoding the truck’s next node and then conditionally decoding the drone action. To further explore the solution space of large-scale instances, the proposed method adopts a multi-rollout learning strategy. We conducted experiments on large-scale TSP-D and VRP-D instances, and the results show that this model outperforms traditional metaheuristic algorithms in terms of both solution quality and computational efficiency.
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Frontiers in Artificial Intelligence 9 2026年3月13日The two-tier vehicle routing problem (2T-VRP) represents a novel variant differing from the traditional VRPs. It can be applied to urban logistics operations system, offering significant potential for mitigating last-mile traffic congestion and reducing delivering costs. Distinct from traditional VRPs, this scenario contains a hierarchical two-tier structure, with trucks operating on the first tier and drones at stations on the second tier. In this study, we first extend the 2T-VRP framework by relaxing the hierarchical constraints, enabling trucks to transport goods not only to robot stations but also directly to customers. This new variant is referred to as the flexible two-tier vehicle routing problem with drone stations (F2T-VRP-DS). Then we formulate the problem as a mixed-integer linear programming (MILP) model. Finally, given the complexity of this problem, an improved adaptive large neighborhood search heuristic algorithm (IALNS) is proposed. The algorithm incorporates an adapted Clark and Wright saving algorithm as the initial solution, and a simulated annealing scheme is employed as the acceptance criterion. The experimental results show that our algorithm can provide high-quality solutions. In particular, compared with the MILP method, our algorithm demonstrates strong competitiveness on large-scale instances, offering smaller time consumption and better solution quality compared to commercial solver like Gurobi. In addition, based on the results of the sensitivity analysis, we further assessed the influence of several key parameters within the F2T-VRP-DS framework.
MISC
6-
2025年9月18日Large Language Models (LLMs) are gaining popularity and improving rapidly. Tokenizers are crucial components of natural language processing, especially for LLMs. Tokenizers break down input text into tokens that models can easily process while ensuring the text is accurately represented, capturing its meaning and structure. Effective tokenizers enhance the capabilities of LLMs by improving a model's understanding of context and semantics, ultimately leading to better performance in various downstream tasks, such as translation, classification, sentiment analysis, and text generation. Most pre-trained tokenizers are suitable for high-resource languages like English but perform poorly for low-resource languages. Dzongkha, Bhutan's national language spoken by around seven hundred thousand people, is a low-resource language, and its linguistic complexity poses unique NLP challenges. Despite some progress, significant research in Dzongkha NLP is lacking, particularly in tokenization. This study evaluates the training and performance of three common tokenization algorithms in comparison to other popular methods. Specifically, Byte-Pair Encoding (BPE), WordPiece, and SentencePiece (Unigram) were evaluated for their suitability for Dzongkha. Performance was assessed using metrics like Subword Fertility, Proportion of Continued Words, Normalized Sequence Length, and execution time. The results show that while all three algorithms demonstrate potential, SentencePiece is the most effective for Dzongkha tokenization, paving the way for further NLP advancements. This underscores the need for tailored approaches for low-resource languages and ongoing research. In this study, we presented three tokenization algorithms for Dzongkha, paving the way for building Dzongkha Large Language Models.
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福音と社会 63(2) 19-41 2024年4月
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2021年5月17日Unpaired image-to-image translation using Generative Adversarial Networks (GAN) is successful in converting images among multiple domains. Moreover, recent studies have shown a way to diversify the outputs of the generator. However, since there are no restrictions on how the generator diversifies the results, it is likely to translate some unexpected features. In this paper, we propose Style-Restricted GAN (SRGAN) to demonstrate the importance of controlling the encoded features used in style diversifying process. More specifically, instead of KL divergence loss, we adopt three new losses to restrict the distribution of the encoded features: batch KL divergence loss, correlation loss, and histogram imitation loss. Further, the encoder is pre-trained with classification tasks before being used in translation process. The study reports quantitative as well as qualitative results with Precision, Recall, Density, and Coverage. The proposed three losses lead to the enhancement of the level of diversity compared to the conventional KL loss. In particular, SRGAN is found to be successful in translating with higher diversity and without changing the class-unrelated features in the CelebA face dataset. To conclude, the importance of the encoded features being well-regulated was proven with two experiments. Our implementation is available at https://github.com/shinshoji01/Style-Restricted_GAN.
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人工知能学会全国大会論文集 JSAI2019 3B3E204-3B3E204 2019年新たな手法や技術により発展している深層学習には、人々の仕事効率を助けたり、とある現象をみて予測を立てたり、デザイナーとなって画像を生成するなど様々な可能性に満ちている。本研究では深層学習を用いて"条件付き"の手書き文字を生成を行った。単なる画像生成ではなく、入力者側が生成したい手書き文字を指定する(生成の条件をつける)ことでその文字を生成することを目的とする。目的達成のために、実験では深層学習モデルとしてDCGANとConditional GANを組み合わせたConditional DCGANを構築、ラベル情報の付加で生成条件がつけられた画像生成のトレーニングを行った。141,319のサンプル訓練データにある数字やアルファベット、カタカナなどの総計96種類の手書き文字の書き分けトレーニングを通じて、インプットの要素として含まれるランダムノイズの次元数がその種類数を上回るようにした学習済みのGeneratorは各種類に対応付けたラベルを指定するだけで、その該当文字を生成できたことを紹介する。
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電子情報通信学会技術研究報告. KBSE, 知能ソフトウェア工学 103(604) 1-6 2004年12月In this paper we propose a composite-server model and make use of the knowledge of the intrinsic composition of its service providing units (personnel or equipment) to derive Qualitative knowledge-based rules for its performance evaluation. The composite server model that takes into account the composite nature of service has wider scope in its applications and can be used to represent a variety of system classes. We use this novel concept in the performance design and improvement of collaborative engineering systems. System modeling is done by Multi-Context Map (MCM) technique. MCM is a de...
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電子情報通信学会技術研究報告. AI, 人工知能と知識処理 103(306) 15-20 2003年9月9日本論では、協調エンジニアリングシステムの性能評価・性能改善を目的とした,定性推論を含有するエキスパート・システム(ES)の設計や実施方法を提案する.ESの推論エンジンに定性推論を適応する動機は、システムのモデルであるMulti Context Map(MCM)待ち行列ネットワークにある三重の入出力コンテキストの相互作用の改善にかかわる計算量・複雑性を回避するためである.ESは、GPSSシミュレーション・データを分析して,ボトルネックを検出し,システムのMCM知識ベースを参考し,定性的規則を利用してシステム性能改善のためのパラメータ・チューニングプランを作る.このESは,協調エンジニアリングにおけるベンチマーク・システムの評価・改善に十分に達成した.
書籍等出版物
2-
CRC Press 2021年 (ISBN: 9780367638368)
講演・口頭発表等
73-
13th International Conference on Awareness Science and Technology (iCAST), Yog Jakarta 2025年11月 招待有り
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NPO Mental Health Care Research Group Chiba (NPO) 2025年6月12日 招待有り
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International Conference on Artificial Intelligence and Data Analytics for Business, Gedu College of Business, Royal University of Bhutan, Bhutan 2025年4月25日 招待有り