Mobility entropy and message routing in community-structured delay tolerant networks

Many message routing schemes have been proposed in the context of delay tolerant networks (DTN) and intermittently connected mobile networks (ICMN). Those routing schemes are tested on specific environments that involve particular mobility complexity whether they are random-based or soci-ologically organized. We, in this paper, propose community structured environment (CSE) and mobility entropy to dis-cuss the effect of node mobility complexity on message rout-ing performance. We also propose potential-based entropy adaptive routing (PEAR) that adaptively carries messages over the change of mobility entropy. According to our simu-lation, PEAR has achieved high delivery rate on wide range of mobility entropy, while link-state routing has worked well only at small entropy scenarios and controlled replication-based routing only at large entropy environments

Relation of size distribution of cracks in superconducting layer to critical current distribution under small voltage probe spacing in rebco-superconducting composite tape

The relation of distribution of crack size to that of critical current under small voltage probe spacing in RE(Y, Sm, Dy, Gd, ….)Ba2Cu3O7−δ layer-coated superconducting tape with stress-induced cracks was studied with a Monte-Carlo simulation method in combination with a model of current shunting at cracks. First, it was shown that the experimentally observed feature that the critical current decreases with increase in distribution width of crack size and voltage probe spacing was reproduced by the present simulation. Then it was revealed that (i) the largest crack among all cracks in the region between the voltage probes plays a dominant role in determination of critical current, and, (ii) when the size of the largest crack is fixed, the large difference in crack size among all cracks acts to raise the critical current value and to reduce the n-value, and, in this phenomenon, the reduction of n-value with increasing difference in crack size is more dominant than the increase of critical current. Finally, it was shown that the distribution of critical current can be described using the Gumbel’s extreme value distribution function as a first approximation under small voltage probe spacing where the influence of the difference in crack size on critical current is relatively small

Essays on aggregate dynamics: externalities, liquidity and financial crises

In the second chapter, we consider a mechanism of unstable fluctuations of aggregate investments by means of a global game approach. For this purpose, we extended a static global game to a dynamic one and paid attention to the effect of past aggregate investments on current profitability. Once this effect of aggregate investments between periods is taken into account, we can show that firms’ equilibrium strategies of investments become highly volatile over time. Moreover, long persistence of high or low economic activity can be explained by this model as well. The third chapter examines the effect of firms’ funding liquidity on macroeconomic dynamics and the role of liquidity markets. Here, we regard liquidity as firms’ accumulated net worth and introduce heterogeneity between firms with regard to their productivities and accumulation of their net worth. From our analysis, we show that under existence of externality between probabilities of liquidity shocks 1) the economy without liquidity markets is highly volatile. 2) Liquidity markets insulate the economy from liquidity shocks. 3) During an unstable economic environment, the economic activity can sharply drop in the existence of liquidity markets. The fourth chapter aims at showing risk shifting behaviour of financial intermediaries in the context of an economic growth model to analyze financial crises. In the low capitalized economy in which a rate of return on safe assets is high and households’ assets are scarce, investing in corporate sectors is more profitable than that of risky assets because the option value from investing in risky assets is low. However, as the economy grows, the rate of return on safe assets is decreasing whereas individual assets are increasing. In this situation, the option values of risky assets are increasing, which gives banks incentive to invest in risky assets leading some of the banks to be insolvent

Resilience of Wireless Ad Hoc Federated Learning against Model Poisoning Attacks

Wireless ad hoc federated learning (WAFL) is a fully decentralized collaborative machine learning framework organized by opportunistically encountered mobile nodes. Compared to conventional federated learning, WAFL performs model training by weakly synchronizing the model parameters with others, and this shows great resilience to a poisoned model injected by an attacker. In this paper, we provide our theoretical analysis of the WAFL's resilience against model poisoning attacks, by formulating the force balance between the poisoned model and the legitimate model. According to our experiments, we confirmed that the nodes directly encountered the attacker has been somehow compromised to the poisoned model but other nodes have shown great resilience. More importantly, after the attacker has left the network, all the nodes have finally found stronger model parameters combined with the poisoned model. Most of the attack-experienced cases achieved higher accuracy than the no-attack-experienced cases.Comment: 10 pages, 7 figures, to be published in IEEE International Conference on Trust, Privacy and Security in Intelligent Systems, and Applications 202

Studies on the Coastal Oceanography in the Vicinity of Fukuyama，Hiroshima Pref. : I. Distribution Patterns of Temperature， Chlorinity， pH and lnorganic Nutrient (Phosphate-P， Ammonia-N， Nitrite-N ， Nitrate-N) Contents of Sea Water in Early February，1968.

In the coldest and driest season of the year (i.e., February 3 and 4, 1968) measurements were taken on water temperature, chlorinity, pH and phosphate-P, ammonia-N, nitrite-N and nitrate-N contents of sea water off the estuary of the Ashida River, occupying 14 stations both at a high and a low water. The water temperature was within a range of 6-8°, its vertical variation being very slight reflecting the vertical circulation of water due to convective cooling. Chlorinity also demonstrated a slight vertical variation due to the same cause in all places except in the close vicinity of the river mouth and in the waste water discharged from a chemical plant. Normal pH values were encountered everywhere except in the vicinity of the chemical plant where values as low as 2.4～8.0pH were measured. Nutrient contents of sea water were low in the offing, and somewhat higher near the estuary of the Ashida River, and abnormally high in the water samples affected by the waste water from the chemical plant. Possible effects of such distribution patterns of sea water properties on the cultured laver were discussed

Studies on the Coastal Oceanography of the Bingo-nada and Hiuchi-nada Regions of the Se to Inland Sea : I. Distribution Patterns of Temperature, Chlorinity, Inorganic Nutrient Contents (Phosphate-P, Ammonia-N, Nitrite-N, Nitrate-N) and Some Other Properties of sea Water in Early February, 1968

About in the middle of the Seto Inland Sea extending east and west, a somewhat pear-shaped sea region is observed; its northern border (i.e., the tip of the pear-shape) being that part of the southern shore of Honshu where Fukuyama and Kasaoka cities are located; its southern border (the bottom of the pear) being the middle portion of the northern shore of Shikoku, where Kan-onji, Iyo-mishima, Niihama and Imabari cities are situated in an east to west line. This sea extension communicates with the shallower Bisan Straits in the northeast; the commonly accepted boundary between them runs from Konoshima on, south to Obi-shima, and then southeast to Misaki. In the west, this sea region is bordered by the eastern edges of the island chain (the Geiyo Islands) extending from Tomo southwest to Imabari, and communicates with the less neritic Aki-nada region by several straits. This sea region measures nearly 1,900 km2 in area and contains about 36 km3 of water. Its diameters are ca. 58 km laterally (Imabari to Kan-onji) and ca. 60 km longitudinally (along the 133°30' E meridian) (Fig. 1). This region can be subdivided into a northern and a southern portion by the arc of small islands including Uo-shima and Ibuki-shima; the former is called Bingo-nada and the latter, Hiuchi-nada. As part of the efforts to clarify the dynamics of organic production in this sea region, the authors performed, in early February, 1968, the measurements of the oceanographical factors named in the title above as well as pH, dissolved oxygen and turbidity of the sea water and also the depth of disappearance of the Secchi disc ('transparency'). Eleven stations were surveyed altogether during a 2-day cruise (Fig. 2). The driest and coldest season of the year was chosen for the observation. This paper presents the results of this examination (Table 1). The survey should be regarded as a preliminary attempt, since the authors did not yet succeed in elucidating the real mechanisms underlying the apparently complicated distributions of some of the measured factors. Following are the noticeable features of the results. Reflecting the convective cooling, the water temperatures proved vertically uniform at all stations except St. 6 (Fig. 3); chlorinity and dissolved oxygen were also nearly uniform vertically at all stations. Geographically, both temperature and chlorinity were highest along the western border of the sea region, and lowered towards the east (Figs. 4 & 5). Both elements reached a minimum near the Bisan Straits; they reached another minimum at the innermost part of Hiuchi-nada (near Iyo-mishima). This distribution pattern may point to the following tendency: the more saline and warmer water distributed to the westward was flowing into Bingo-nada and Hiuchi-nada through the straits of the Geiyo Islands and was then cooled and diluted while flowing eastward. It is also inferable that less saline and colder water was found in the Bisan Straits. The percentage saturation of dissolved oxygen was vertically uniform at all stations. Along the western border it was somewhat lower (ca. 96%); it showed a general trend towards increase towards the east except for the considerably low values (ca. 93%) at St. 15 (Table 1). Concentrations of inorganic nutrients, which were determined by absorptiometry using unfiltered water samples, showed to be within the following ranges: phosphate-P, 0.28-0.53; nitrite-N, 0.0-0.40; nitrate-N, 0.6-1.7 and ammonia-N, 0.0-5.3 µg-atoms/l (Figs. 7 & 8). It was difficult to find any pronounced regularity regarding the vertical and/or geographic variations in their concentrations. This difficulty might have been overcome to a considerable extent if simultaneous measurements had been taken of organic phosphorus and nitrogen of dissolved and particulate forms as well as of the activities of marine organisms in situ (particularly of phytoplankton). The Secchi disc 'transparency' was about 7 m along the western border, about 5 m in the central part, and between 6 and 8 m in the eastern part of the surveyed region. The only exception was the unexpected high value (11.6 m) at St. 15 (Fig. 6). The light scattering capability (‘turbidity’) of the water samples from various depths (except the bottom layer) was comparable with that of kaoline suspensions of 0.7-2.6 ppm. In neither vertical nor geographic distribution of turbidity, any pronounced regularity could be detected.Special Project Research “Studies on the Dynamic Status of Biosphere” supported by the Ministry of Education. This study was carried out as a part of JIBP Project

感染予防からみた緑茶の特性に関する研究

We investigated the infection-preventive characteristics of Japanese green tea (middle grade) in reference to itscatechin (CAT) concentration. Colorimetric analysis showed that CAT was extracted most effectively at 80℃. When green tea extract (GTE) was prepared from the same green tea leaves (5g/80ml water) repeatedly six times at 80℃ for 1 min, almost the 2/3 of total CAT content was extracted during the first three extractions in which the second extraction gave the highest CAT concentration. Therefore, GTE prepared under this condition (5g/80ml water at 80℃ for 1 min) was referred to as standard GTE (SGTE) in this study. Bacteriological studies using Staphylococcus aureus, Escherichiac oli and Pseudomonas aeruginosa showed that the maximum inhibitory and bactericidal dilutions of the second SGET were ranged in 8-and4-fold dilutions, corresponding to 0.33mg/ml and 0.68mg/ml CAT concentrations, respectively, against either bacterial species and the differences between these two values were within 2-fold dilutions, indicating that SGTE shows the bactericidal activity. However, SGTE required as long as 4 to 5 h for bactericidal time in sharp contrast to iodine with that of as short as 1 min. When SGTE with CAT concentration ranging 1.2 mg/ml to 2.7mg/ml was incubated with influenza A/Aichi virus at 37℃ for at least 30min, SGTE also completely inhibited viral hemagglutination (HA) activity essential for the viral attachment to cell surface. The CAT-deficient SGTE, prepared by the treatment with FeCl_3, could not show both bactericidal and HA inhibitory activities, confirming that CAT in GTE is mainly responsible for these activities. In summary, GTE might be taken as a beneficial herbal medicine to promote the infection-safety conditions in the patients. However, on the application of GTE, its advantage/disadvantage and presence of sufficient CAT concentration should betightly recognized.緑茶（煎茶）の抗菌性とインフルエンザウイルス赤血球凝集（HA）活性阻害の特性を検証した．酒石酸鉄比色法による検討から，低温域（50℃と65℃）より高温域（80℃と91℃）でより多くカテキン（CAT）は抽出され，就中80℃が最大CAT量を示した．5g茶葉/80ml水，80℃，1分（標準緑茶液:SGTE）で６回抽出したところ，２回目で最高CAT量（2.7mg/ml）を示し，３回目までにほぼその2/3が抽出された．黄色ブドウ球菌，大腸菌と緑膿菌に対するSGTEの最大発育阻止と最大殺菌希釈度の差は，どの菌に対しても２倍以下であり，緑茶は，広範囲性かつ殺菌的作用を示すことが確認された．但し，ヨード液の１分に比べ，殺菌時間は４～５時間と極めて長いことが注目された．種々CAT量を有するSGTEを，種々時間37℃でインフルエンザウイルスと接触させたところ，CAT量1.2mg/ml～2.7mg/mlの範囲で，30分接触で完全にHA活性を阻害した．さらに，塩化第二鉄処理によるCAT除去SGTEには，抗菌作用も抗HA作用もないことから，種々ある緑茶成分のうち，CATが主な有効成分であることが示された．これらから，緑茶を感染予防として活用する際には，遅効性であること，また十分量なCAT含有（少なくとも1mg/ml）ことの認識は重要であると思われた

Cooperative awareness using roadside unit networks in mixed traffic

International audienceVehicle-to-vehicle (V2V) messaging is an indispensable component of connected autonomous vehicle systems. Although V2V standards have been specified by the European Union, United States, and Japan, the deployment phase represents mixed traffic in which connected and legacy vehicles co-exist. To enhance cooperative awareness in this mixed traffic, we assessed the special roadside unit that we developed in our previous work that generates required V2V messages on behalf of sensed target vehicles. In this paper, we extend our earlier work to propose a system called Grid Proxy Cooperative Awareness Message to broaden the cooperative awareness message dissemination area by connecting infrastructure using high-speed roadside networks. To minimize delay in message delivery, we designed the proposed system to use edge computing. The proposed scheme delivers cooperative messages to a wider area with a low delay and a high packet delivery ratio by prioritizing packets by their respective safety contributions. Our simulation results indicate that the proposed scheme efficiently delivers messages in heavy road traffic conditions modeled on real maps of Tokyo and Paris

Point-focusing monochromator crystal realized by hot plastic deformation of a Ge wafer

A point-focusing Johansson monochromator crystal prepared by hot-pressing a Ge single-crystal wafer is demonstrated. By using 333 diffraction, Cu Kα radiation was focused onto a small spot