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Preliminary evaluation of a congestion control method using reinforcement learning for adopting environment changes
No full textインターネットが社会基盤として不可欠な存在となる中、ネットワークの輻輳制御は通信品質を維持する上で重要な役割を担っている。NewReno や CUBIC をはじめとする多くの輻輳制御アルゴリズムは、事前に定めたルールに基づく静的なアルゴリズムとして動作するため、ネットワーク環境の変化に応じた最適化が難しい問題がある。この問題を解決するため、強化学習を利用した動的なアルゴリズムによる輻輳制御の研究が始まっている。しかしながら、先行研究では行動の選択や報酬の与え方といった強化学習としての基本的な評価が十分に行われていない。そこで本研究では、深層強化学習を用いた新しい輻輳制御アルゴリズム「RL-NewReno」を実装し、その性能評価を行う。実験の結果、提案手法は既存の NewReno に比べて平均スループットが最大で約 2% 向上することを確認した。As the Internet becomes an indispensable part of our social infrastructure, congestion control plays an important role in maintaining communication quality. Many congestion control algorithms, such as NewReno and CUBIC, operate as static algorithms based on predefined rules, and there is a problem with the difficulty of optimizing them in response to changes in the network environment. To solve this problem, research efforts have begun on congestion control using dynamic algorithms that utilize reinforcement learning. However, in the existing researches, the basic evaluation of reinforcement learning, such as the selection of actions and the way in which rewards are given, has not been sufficiently carried out. Therefore, in this research, we proposed and implemented the new congestion control algorithm RL-NewReno using deep reinforcement learning and evaluated its performance. Through simulation evaluations, we confirmed that the proposed method improved the average throughput by about 2% at maximum compared to the existing NewReno.電子情報通信学会 情報ネットワーク研究会 (IN)/ネットワークシステム研究会 (NS). 令和7年3月6日～令和7年3月7日. 沖縄産業支援センター、沖縄県.IEICE Technical Committee on Information Networks (IN)/Technical Committee on Network Systems (NS). 2025/03/06-2025/03/07. Okinawa Industry Support Center, Okinawa
超弦理論のコンパクト化およびモジュライ安定化から導かれるフレーバー構造
No full textWe study the realization of flavor structures in the Standard Model of particle physics from the string-inspired effective field theories. Firstly, we study magnetized toroidal compactifications including T 4 and T 4/ZN orbifold models within ten-dimensional N = 1 super Yang-Mills theory. Chiral fermion zero-mode wavefunctions and their degeneracies are explicitly analyzed. Conditions needed to realize three-generation models are clarified. We use modular transformation to count the number of zero-modes systematically. Secondly, we study the stabilization of the complex structure modulus τ of a toroidal extra-dimensional space since its vacuum expectation value is related to flavor structures in four-dimensional modular flavor symmetric models. We analyze the one-loop Coleman-Weinberg potential which results from the radiative corrections of matter fields whose mass terms are written by modular forms. We have discussed the possibility of slightly shifting the modulus vacuum expectation value from the Z3 fixed-point τ = e2πi/3 where the tree-level potential is minimized. Indeed, such a small deviation from the fixed point can naturally explain the hierarchical masses and mixing angles of quarks and leptons within modular flavor symmetric models. Depending on the choice of modular forms, the number of species contributing to the radiative corrections, etc., modulus can slightly deviate from the fixed point. Lastly, we study spontaneous CP violation through moduli stabilization within four-dimensional N = 1 supergravity model. In a CP invariant modular flavor model, the only source of CP violation is the vacuum expectation values of complex structure moduli. We have succeeded in realizing CP-breaking vacua with or without supersymmetry by the combined effects of Type IIB three-form flux and modular symmetric couplings between matter fields and the moduli. We have also revealed some useful properties of CP and modular invariant scalar potential which are model-independent
微視的反応理論による中高エネルギー原子核反応の研究
No full text原子核衝突による全反応断面積とは、非弾性散乱が起きる確率を表す物理量である。全反応断面積は、原子核の密度分布を反映しており、弱く束縛した中性子が原子核の周囲を回っている中性子ハロー核や 2クラスター構造を取る原子核といった不安定核の大きさや構造の特徴を調べるための指標となっている。全反応断面積に関連した以下の 3 つの研究を行った。1. 電子や陽子を用いた散乱実験による全反応断面積の観測がされてきたが、反陽子散乱についてはその有用性はあまり知られていない。反陽子-核子散乱の全断面積は陽子-核子散乱の数倍程度あり、反陽子散乱は散乱とは異なった性質を示すことが期待される。そこで、反陽子-原子核散乱をGlauber 模型で記述することを試みた。反陽子-原子核散乱の全反応断面積を計算し、陽子散乱と比較しながら解析することにより、陽子散乱が中心密度の 1/10 程度の密度領域まで調べることができるのに対し、反陽子散乱は 1/100 程度の密度領域まで感度があることが分かった。中性子ハロー核の密度分布を例に、反陽子散乱の原子核密度分布研究に対する有用性を議論する。2. 全反応断面積から核の大きさが比例関係を持っているという考えは、原子核衝突が完全吸収の黒球模型に近似できるという仮定のもとで成り立っているが、衝突する原子核同士の重なりが小さいところでは、吸収が不完全となる場合がある。そこで、原子核散乱における不完全吸収反応について調べた。Glauber 模型を用いて 12C ‐原子核散乱や陽子‐原子核散乱の反応率を計算し、吸収の不完全性を定量化した。また、不完全吸収反応によって起きる現象の例として、C 同位体の陽子過剰核の 12C 散乱や陽子散乱の全反応断面積を取り上げ、原子核半径の増加が必ずしも断面積の増加に繋がらないことを示した。3. 原子核‐重陽子散乱による全反応断面積は、同じ原子核による陽子散乱と中性子散乱の全反応断面積の和よりも小さくなることが知られている。この現象は、蝕効果と呼ばれる、一つの核子またはクラスターが、もう一方の核子またはクラスターの影に隠れることで、断面積に欠損が生じる効果によるものであると考えられる。そこで、2 クラスター原子核の蝕効果について調べた。8Be(4He +4 He) や 44Ti(4He +40 Ca) といった 2 クラスターの構造を取る原子核について、全反応断面積を計算し、それぞれのクラスターでの散乱の断面積の和と比較し、断面積の減少を確認した。2 クラスター原子核のクラスター間距離について、その波動関数を変化させて断面積の減少度がどのように変化するかを調べた。また、その結果を、2 クラスター原子核を古典的な 2 つの剛体球とみなした場合の全反応断面積の結果と比較することにより、蝕効果の有無およびその性質について議論した。今回の研究を通し、原子核反応の全反応断面積を用いた原子核構造研究について調べた。陽子、12C などの原子核、反陽子など、原子核散乱に用いる入射粒子によって反応の強さが変わり、反応の不完全性も異なる。それによって全反応断面積や、全反応断面積の原子核半径や粒子数に対する関係性にも違いが生じるので、それらの入射粒子を用いた反応を比較することで、ハロー原子核の外縁部の密度や、クラスター原子核のクラスター間距離といった、不安定核の構造の理解に繋がることが期待される
家畜ふん堆肥化過程におけるアンモニア揮散抑制を目的としたバイオ炭添加の効果
No full textIn modern agriculture, composting is crucial for managing different agricultural wastes, including livestock manure. However, ammonia emissions during manure composting pose significant challenges, such as odors, air pollution, human-health risks, and nitrogen loss. While various mitigation strategies have been developed, including physical, chemical, and biological methods, they often face limitations, particularly under high ammonia concentrations. Biochar, a by-product of biomass pyrolysis, has emerged as a promising solution due to its large surface area, high adsorption capacity, and ability to influence microbial activity, which can help reduce ammonia emissions. However, its full potential in enhancing existing ammonia removal techniques remains underexplored. Hence, this study investigates how biochar can improve the performance of two representative ammonia mitigation methods?additives during composting and biofilters?towards achieving zero ammonia emissions during composting. Biochar application during composting (co-composting) is valued for biochar’s large pore volume, oxygen-containing functional groups (OFGs), and nutrient content, which enhance NH3 adsorption and nitrification. However, the effectiveness of biochar depends on its production conditions, such as type of feedstock used and pyrolysis temperature. To maximize its performance, we investigated how biochar properties affect ammonia reduction during composting. Biochars were produced from dairy manure and Japanese larch at 300 and 800°C. The composting experiments were conducted by mixing biochar (12 g) with dairy manure (300 g). Biochars produced at 300°C were more effective in reducing ammonia emission during composting than those made at 800°C. This was attributed to their higher content of OFGs, cation exchange capacity, ash content, and lower pH, which enhance ammonia adsorption and nitrification. However, despite the effectiveness of biochar, some ammonia emissions remain unavoidable during composting, indicating that biochar addition may not be sufficient to achieve zero ammonia emissions during composting. Compost biofilters offer a promising solution for complete ammonia removal by combining adsorption with biological processes. However, during manure composting, high ammonia concentrations can inhibit microbial activity within biofilters, reducing their efficiency. Maintaining microbial activity is essential for continuous ammonia removal. To address this challenge, we added biochar to the compost biofilters (co-biofiltration). We hypothesized biochar’s high adsorption capacity and large surface area can help capture ammonia directly, reducing its toxicity to microbes. We explored the effect of co-biofiltration using dairy manure biochar (produced at 300°C) at different ratios (0 to 50%) under ammonia concentrations of 1000 and 2000 ppm. All biochar-mixed biofilters showed improved ammonia removal at both concentrations, with the 25% biochar-mixed biofilter achieving the highest performance. Ammonia removal in biofilters occurred through NH3 adsorption, chemical precipitation, nitrification, and denitrification, all enhanced by biochar at 1000 ppm. However, at 2000 ppm, microbial activity was still inhibited even with biochar due to rapid ammonia accumulation. These findings suggest that compost biofilters can achieve continuous and complete ammonia removal at lower ammonia concentrations, which can be further enhanced by mixing biochar. Therefore, to ensure continuous complete removal of ammonia, it is crucial to reduce ammonia concentrations during composting. In this context, the integration of cocomposting and co-biofiltration may offer a promising approach in achieving zero ammonia emissions. The next phase of the study investigated the synergistic effect of co-composting and cobiofiltration on ammonia removal during composting. Both biofilters (with or without biochar) achieved complete ammonia removal by reducing ammonia emissions during composting through co-composting. Co-biofiltration, in particular, enhanced the long-term reuse potential by improving nitrification during cocomposting. Overall, the findings of this study demonstrate that zero ammonia emissions can be achieved during manure composting, with biochar playing a pivotal role through the combined processes of cocomposting and co-biofiltration