Visual monitoring of construction worksites through the installation of surveillance cameras has become prevalent in the construction industry. These cameras also are useful for automatic observation of construction events and activities. This paper demonstrates the use of a surveillance camera for assessing tower crane activities during the course of a workday. In particular, it seeks to demonstrate that the crane jib trajectory, together with known information regarding the site plans, provides sufficient information to infer the activity states of the crane. The jib angle trajectory is tracked by using two-dimensional to three-dimensional rigid pose tracking algorithms. The site plan information includes a process model for the activities and site layout information. A probabilistic graph model for crane activity is designed to process the track signals and recognize crane activity as belonging to one of two categories: concrete pouring and nonconcrete material movement. The experimental result...

Phased energy storage technologies are highly advantageous and feasible for storing and utilizing clean renewable energy resources, for instance, solar energy and waste heat, and it is an effective method to improve energy efficiency and save energy. However, phase change energy storage has some problems, for example, low thermal conductivity and phase change leakage, which lead to limited application. In this paper, anisotropic graphene aerogels were prepared by ice crystal template method with high thermal conductivity of graphene, and silver was attached to the pore wall graphene sheets and the graphene sheet boundaries of the aerogels. The results show that anisotropic graphene aerogels were successfully prepared, and SEM and EDS indicate that up to 9.14 at % silver was successfully attached to the graphene sheets and boundaries. The anisotropic thermal conductivity of the PArGO phase change composites after adsorption of the paraffin is significant, with a maximum axial thermal conductivity of PArGO of 1.20 W/(mK) and radial thermal conductivity of 0.54 W/(mK), compared to the pure paraffin (0.26 W/(mK)) increased by 362% and 108%, respectively. The enthalpy of the composite has been reduced to 149.6 J/g due to the silver particles attached, but the thermal properties have been greatly improved. In experiments simulating real temperature changes, PArGO achieves phase transitions very fast, with a 74% improvement on thermal efficiency of storage and discharge over the pure paraffin.

Cargo airdrop has long been one of the most important measures to deal with urgent immediate needs, such as providing assists in military operations and sending relief to disaster areas, just to name a few. Because it is carried out during flight, it is necessary to investigate the influences of the drop process on flight characteristics to ensure successful execution of the task. This article mainly studies the modeling of flight systems in large flying transport planes with cargo moving in it. By building up rational frame definition, the complete nonlinear force and moment equations are established by using the Newton's second law and the Euler angle relation of rigid body. Then the effects of moving process parameters including cargo mass and moving items upon the flight are analyzed. Computerized simulation of the whole process shows that the cargo moving would exert enormous effects upon the flight characteristics and quality of controlling; therefore, a special control strategy should be developed to guarantee the required system performances.

During airdrop of heavy load, the flight parameters vary continuously as the load moves in the hold, and change suddenly when the load drops out. This process deteriorates the flight quality and control characteristic as the load becomes heavier. Based on the simplified airdrop flight equations, the backstepping and switch control methods are developed to tackle the flight state holding and disturbance/uncertainty (such as large-scale flight condition, pilot manipulation error, system measure delay, etc.) attenuation problem in this paper. Moreover, these methods can be used as a reference for pilot manipulating during airdrop. With the backstepping theory, an adaptive controller is synthesized for the purpose of stabilizing the transport when the load moves in the hold, and then a coordinated switch control method is used to control the aircraft when the condition jumps from the existence of load at the rear of fuselage to no load in the fuselage. Simulation results show that the proposed controllers not only provide effective state holding during airdrop, but also achieve robust performance within wide flight conditions.