•The ASR-induced micro-cracking was visualized with the digital image correlation.•The DIC-based estimates of the strain were in good agreement with other methods.•The pessimum showed different ...expansion depend on the type of non-reactive aggregate.•An artificial lightweight aggregate attenuated the ASR-induced expansion of concrete.•The mechanical properties of the aggregate affect the ASR-induced crack growth.
This study visualized the development of micro-cracks in concrete due to the progression of the alkali–silica reaction (ASR) in two dimensions using a digital image correlation (DIC) technique. First, a preliminary experiment to determine the optimum specimen size for DIC was conducted on three specimens with different thicknesses. The results show that the ASR neither caused macro-level expansion nor attenuation of the ultrasonic propagation velocity in concrete specimens with a thickness of 10 mm. This was attributed to the leakage of the alkali–silica gel from the surface. On the other hand, we found that specimens with a thickness of 30 mm or greater were suitable for visualizing strain distributions on the concrete surface. Second, we examined the effects of the mechanical properties of aggregates on the ASR-induced crack propagation in concrete. The specimen dimensions were chosen based on the results of the preliminary experiment, and the mixing ratios selected ensured the manifestation of pessimum effects. The degree of concrete expansion depended on the type of non-reactive aggregate used in the mixture. Furthermore, the ASR-induced expansion of concrete was significantly reduced with the introduction of an artificial lightweight aggregate as the non-reactive aggregate, and the mechanical properties of the aggregate(s) were found to affect the ASR-induced crack growth.
The biologging approach of attaching a logger to the body of an animal provides information that cannot be obtained by conventional direct visual observation. Marine zoologists have used this ...technique for observing sperm whales preying on giant squids in the deep sea. However, it is almost impossible to capture a sperm whale to attach a logger, because of its large size. Therefore, researchers have used a long pole to attach a logger from a ship to the back of sperm whales. Unfortunately, this method is risky and requires a skilled team. In this paper, we propose a logger attaching system using a drone to solve this problem. The proposed method can be trained on land; thus, it is relatively easy to train a team, and the mobility of the drone can shorten the installation time. Several pieces of equipment developed for the proposed method are described in detail. Furthermore, field experiments were performed with sperm whales to confirm the feasibility of the system. A suction cup of the seventh prototype of the whale rover was adsorbed onto the back of a sperm whale. Although a complete installation was not possible, it was demonstrated that operation was possible in a short time using the proposed method.
There is an urgent need to automate and improve the efficiency of agricultural work, and IoT systems are attracting attention to increase the efficiency of agricultural operations. This study focuses ...on Aquaponics, an efficient agricultural method that combines hydroponics and aquaculture. Aquaponics operations need to not only manage the environment for plants, bacteria, and fish but also ensure that the plants and fish are growing properly. Therefore, we propose sensor network system that aims to improve the efficiency of aquaponics operations by analyzing information on the state of the growing environment obtained from various sensors, as well as the growth rate of plants and fish. Furthermore, to reduce the workload of administrators for device management, we propose an efficient management system with a container orchestration platform that dynamically deploys applications to nodes installed in the field. The system adopts a highly available architecture for farms where the condition of the network communication environment fluctuates. The proposed architecture is equipped with dynamic service deployment that automatically switches between edge and cloud computing based on the network conditions. Through performance evaluation, we confirm that containers equipped with the proposed analysis method can be automatically deployed and operated on edge devices using the container orchestration platform.
Indoor thermal environments in various offices in hot and humid climate regions of Asia are overcooled by air conditioning (AC) systems. Overcooled environments affect the occupants’ health and lead ...to excessive energy consumption. This study aims to clarify the association of occupants’ subjective symptoms with indoor thermal environments through field surveys conducted in Thailand, Indonesia, and Singapore. Indoor thermal measurement and thermal comfort surveys, including a questionnaire about thermal sensation and subjective symptoms, were conducted, targeting 599 occupants in 11 offices. The results showed that the mean indoor operative temperatures (Top) for all cities were lower than 24°C. More than half of the occupants wore light clothing ensembles (0.30–0.59 clo). Therefore, 42.6% of the occupants’ calculated predicted mean vote (PMV) was less than −0.5. The correlation between indoor temperatures and the actual percentage of occupants who reported subjective symptoms (APSS) was analyzed. The lower Top and standard new effective temperature (SET*), the more APSS was increased. In each temperature category of below 24.5°C, more than 30% of occupants reported subjective symptoms related to coldness. Therefore, the findings from this study suggest that raising Top higher than 24.5°C is a first step to minimize the harmful effects of the cooling environments on the occupants’ health in this region. As the number of samples in the higher temperature range was insufficient in this study, further experiments in actual offices are necessary to verify the reduction of occupants who report subjective symptoms while raising the setpoint temperature.
•This study clarifies association of occupants’ symptoms with overcooled environments.•The methodology involved thermal comfort surveys of 599 occupants in 11 offices.•The indoor operative temperatures mean for all surveyed cities were lower than 24°C.•More than half of the occupants wore light clothing ensembles (0.30–0.59 clo).•Below 24.5°C, more than 30% of occupants reported symptoms related to coldness.
There is an urgent need to automate and improve the efficiency of agricultural work because traditional agricultural work becomes a heavy burden for the elderly who makes up many of the agricultural ...workers. Therefore, in recent years, aquaponics is attracting attention as a good solution for the problem. Aquaponics is an efficient farming system that combines aquaculture and hydroponics. In the system, the bacteria decompose fish excrement, the plants absorb the decomposed excrement as nutrients, and the purified water returns to a fish tank. This cycle is automated to greatly reduce the amount of consumption of water and fertilizer. In order to keep the accurate cycle, the system should not only manage the environment so that the bacteria can properly decompose fish waste, but also measure the growth condition of the plants and fish accurately. However, the automatic estimation of the growth rate of the fish in the water is a difficult problem because the existing camera-based method cannot easily be applied to the fish living in the water. Therefore, in this study, we propose a new sensor network system with a function to quantify the size of fish as well as plants by utilizing not only a general depth camera that uses infrared rays but also a stereo camera with multiple cameras. Through the performance evaluation, it is confirmed that the proposed method can estimate the leaf area of plants and the standard length of the fish with high accuracy.
The construction boom of Nikkei farmhouses in Tome-Acu started in the early 1950s, with improved economic conditions as a background. Typically, those houses have a special dining room and living ...room for guests and another living room for family in the interior. In addition, a hall allows them to gather. That style has tended to disappear from inside residences that have been constructed recently, with the addition of wide verandas. This study clarifies the actual conditions of that change based on a field survey. The factors affecting that change were further examined in relation to living condition.
The frequency of VoIP calls on IP networks is increasing. The maximum number of VoIP sessions for a given quality of service guarantee does not necessarily match the number obtained by dividing the ...link bandwidth of the VoIP session because of the statistical multiplexing effect. For reducing the blocking probability of VoIP calls, we propose a VoIP admission control with a state probability. We determine the maximum number of VoIP calls by using the expected packet loss rate. We show the effectiveness of our method in a numerical analysis comparing it with the conventional method. The analysis shows that the maximum number of connections derived by our method is larger than that of the conventional method. Therefore, our method decreases the blocking probability.
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