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The mutual interference among wireless nodes is a critical factor in the Internet-of-Things (IoT) era due to its dense deployment. Due to its large coverage area, wireless nodes may not be able to detect the on-going communication of other nodes in a long range wide area network (LoRaWAN), which is one of the low power wide area (LPWA) standards. This results in packet collision. The packet collision among LoRaWAN nodes significantly deteriorates network performance functions such as packet delivery rate (PDR). Furthermore, if packet collision happens, LoRaWAN nodes must retransmit packets, draining their limited battery power. Thus, mutual interference management among LoRaWAN nodes is important from the perspectives of both network performance and network lifetime. However, due to its large network size, it is difficult to explicitly comprehend the wireless channel environment around each LoRaWAN node, such as the relation among other LoRaWAN nodes. Thus, in this paper, we utilize the powerful machine learning technique. The wireless environment around LoRaWAN nodes are learned, and the knowledge is utilized for resource allocation in order to improve PDR performance. In the proposed method, Q-learning is adopted in a LoRaWAN system, and the weighted sum of the number of successfully received packets is treated as a Q-reward. The gateway (GW) allocates resources to maximize this Q-reward. The numerical results considering LoRaWAN elucidate that the proposed scheme can improve average PDR performance by about 20% compared to the random resource allocation scheme.

With the progress of internet of things (IoT), devices with a wireless ad-hoc function are being increasingly used. For future wireless communication systems, the use of millimeter waves, which are strongly affected by shadowing, is considered. We focus on energy-efficiency [bits/J] that combines throughput and energy consumption, which is expected to be important in future wireless communication systems, to realize smart IoT in a shadowing environment. In this paper, we compare the effects of two parameters, including shadowing deviation values, on energy-efficiency in three dimensions for both AODV and OLSR protocols in a shadowing environment using network simulator, ns3.

With the further development of the internet-of-things (IoT), numerous nodes are expected to be densely deployed. If multiple nodes simultaneously transmit packets on the same frequency channel, packet collision can occur at the gateway leading to packet loss. By transmitting an acknowledgment (ACK) signal to the node whose packet was correctly received by the gateway, the other nodes can initiate packet retransmission in order to resolve packet loss. However, ACK signal transmission is required from the gateway to all the nodes, increasing the gateway processing load and impacting the duty cycle (DC) restriction on the gateway. In this paper, we propose an autonomous decentralized frequency resource allocation scheme for LoRaWAN, aiming to reduce the number of packet collisions and the gateway processing load. We implement the proposed approach, and demonstrate its effectiveness through computer simulation and experimental evaluation.

Due to the wide spread of machine-to-machine (M2M) communications and Internet-of-things (IoT), large number of wireless terminals are densely deployed. Under such dense deployment, it is necessary to manage the mutual interference among wireless terminals. Carrier-sense multiple access/collision avoidance (CSMA/CA) is one of the random access schemes that allow wireless terminals to access a channel while avoiding such mutual interference. However, if two wireless terminals are in the hidden terminal relation, a packet collision may happen as the carrier sense mechanism does not work. This results in the degradation of packet delivery rate (PDR) performance. Whether or not particular two wireless terminals are in the hidden terminal relation is an unobservable information from a network controller such as an access point (AP). In this paper, we tackle this problem by using machine learning. By using machine learning, the wireless controller makes a guess of the unobservable information from the observable information. We will use the wireless terminal locations and received signal strength at APs as the observable information. Based on the estimated unobservable information, the wireless controller assigns orthogonal resources to the wireless terminals that are in the relationship of hidden terminal in order to avoid the packet collision. Numerical results confirm that the proposed approach can improve the PDR performance up to 15% compared to the random resource allocation scheme.

A low power wide area network (LPWAN) is one of the promising technologies intended for Internet of Things (IoT). The LPWAN features a wide communication area that is a few kilometers to a few tens of kilometers; low power consumption is achieved using a battery. This study measures the transmission characteristics of a LoRaWAN which is one of the LPWAN. Therefore this paper shows the measured results in field experiment of certain cases: a road along the Tamagawa river in Tokyo, inside and around campuses, and a medium city environment. These measured results indicate that it is difficult to accurately perform a carrier sensing for LoRaWAN. Subsequently, we propose a method to realize the accurate spectrum sensing for spectrum sharing considering sensing sensitivity.

As means of the reduction of the environmental load, the change of the materials of the product is thought about. In order to grasp the load quantitatively, life cycle assessment is performed.In this report, the matter that we should pay attention to about environmental load of the materials of the railway is explained. In addition, as examples of evaluation of CO2 reduction effect, geo-polymer concrete production and the maintenance reduction effect resulting from the use of carbon contact strips on pantograph head are shown.

The superconducting magnetically levitated transportation (Maglev) system requires ground coils suitable for long-term outdoor use along the entire length of the guideway, meaning that the assurance of stable performance and high reliability is an important consideration in developing these coils. Durability verification testing from the level of the component materials to the actual product on the assumption of commercial service is therefore necessary to guarantee total reliability. We performed flexural fatigue tests using specimens made of the epoxy resin used for actual propulsion coils. The results were used to create a fatigue limit diagram as well as a diagram to verify Miner's Law. We then confirmed the correlation between the color difference and the flexural strength by comparing the outdoor exposure test results with those of accelerated artificial exposure testing.

Intermodalism has become one of the most important ways of transporting freight with the development of social economy and industry. In order to correspond to the changing nature of freight transport and to improve railway transport effectively, it is essential to upgrade conventional freight stations to provide sophisticated facilities where loading/ unloading services are directly handled on siding tracks for arrival and departure. In this paper, we discuss the improvements of railway freight stations based on advantage analysis by comparing the conventional type with the new one. We then cover the development of a mode-share model using stochastic distribution of freight time value. Next, we estimate the modal shift of freight resulting from improvements to station facilities, and finally we investigate the related environmental effects such as reduction in CO2 emissions.

This paper describes the environmental burden associated with various transportation modalities in Japan between 1985 and 2000 by employing an input-output type analysis. Measured greenhouse gases in the study included carbon dioxide, sulfur oxide, and nitrogen oxide. The modalities assessed that produced these gases were road traffic, aviation, railways, and coastal vehicles. It was found that, in the given time frame, the amount of such gases released from the railway modality was lower per unit than that of other modalities. Analysis of infrastructure burden took into account both construction and maintenance. For vehicular analysis, researchers considered both production and maintenance and, to determine the burden from operational energy, researchers analyzed both supply as well as consumption.

Bile salts can be cytotoxic to mucosal surfaces, because of their detergent properties. This is not normally seen under physiological circumstances in the gall-bladder. To further study normal mucosal defence mechanisms, the present study was performed to examine the effects of liposomes and hydrophilic bile salts on hydrophobic bile salt-induced release of radiolabelled glycoproteins from explants of guinea-pig gall-bladder. Glycoprotein release was correlated with the degree of hydrophobicity of bile salts, as determined by the retention factor in reversed-phase high-performance liquid chromatography. Hydrophobic bile salt-induced release of glycoproteins was reduced by liposomes and hydrophilic bile salts. The inhibitory effect of liposomes was directly related to the degree of saturation of their fatty acyl chains, and that of hydrophilic bile salts was related to the degree of hydrophilicity. These findings suggest that vesicles and hydrophilic bile salts may play a cytoprotective role against membrane damage passively caused by hydrophobic bile salts in the biliary system, and that such damage may occur according to the quantitative and qualitative imbalance among these factors.

The effect of a concomitant infusion of organic anions, structurally related phthaleins, on bile flow was studied in anaesthetized dogs. A combination of rose bengal and sulfobromophthalein was found to uniquely and synergistically produce an acute, reversible form of intrahepatic cholestasis (< 10% of control level). This phenomenon was not observed with the administration of those individual organic anions at concentrations previously associated with the induction of intrahepatic cholestasis. The infusion of either a micelle forming bile salt, sodium taurocholate, or a non-micelle forming bile salt, sodium dehydrocholate, rapidly reversed the intrahepatic cholestasis (within 20 min after bile salt infusion). During the choleretic phase immediately following the bile salt infusion, a transient but marked hypersecretion, a disproportionately increased output in relation to that of bile acids, of biliary phospholipid (176% of control level by taurocholate and 138% of control level by dehydrocholate), and an even more striking amount of biliary protein hypersecretion were observed (392% of control level by taurocholate and 357% of control leverl by dehydrocholate). Although the significance of these new post-cholestatic observations requires clarification, it is suggested that the intrahepatic cholestasis induced by organic anions reflects a reversible defect in the mechanism(s) involved in transcellular transport.