In this report, we studied the electron transport through cyclic π-conjugated molecules. The model system consists of metalloporphyrin with two thiol groups at either 9,11-substitution (P-connection) or 1,5-substitution (D-connection) which form chemical bonds with gold electrodes. We investigated 10 typical bivalent metals as the metal-molecule-metal junctions using first principle density functional theory and nonequilibrium Green's function calculations. Due to the particular electron transport paths, all models in P-connection show similar I-V curves, indicating that the electron does not pass through the metal center in this configuration. In the D-connection, the electron takes the path through the metal center, leading to considerable difference in the I-V curves between the different metalloporphyrins. This means that the D-connected metalloporphyrin is potentially applicable in chemical sensor. We also studied a prototype for chemosensing the CO molecule theoretically at the same level.

Bearing failure is the main cause of breakdown in rotating machinery. This paper proposes a new method for diagnosing faults and assessing the health of bearings using the Mahalanobis–Taguchi System (MTS). Our approach utilizes empirical mode decomposition and singular value decomposition to process the non-linear and non-stationary vibration signal of a bearing. In this method, the vibration signal is first decomposed to a number of intrinsic mode functions and a residue to form a feature matrix. Singular values of this feature matrix are obtained by SVD, at which point MTS is employed. MTS provides: 1) a computational scheme based on the Mahalanobis distance for fault clustering; and 2) Taguchi methods to extract the key features. In addition, we formulate a new assessment method that obtains the health index of a bearing. This method is based on a normal condition dataset, without the need for failure data, which is a notable indicator for bearing health tracking and defect detection at the incipient stage. Finally, the feasibility and efficiency of this method is validated by two different bearing experiments.

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The emergence of 5G communication systems will not replace existing radio access networks but will gradually merge to form ultra-dense heterogeneous networks. In heterogeneous networks, the design of efficient vertical handoff (VHO) algorithms for 5G infrastructures is necessary to improve quality of service (QoS) and system resource utilization. In this paper, an optimized algorithm based on a multi-objective optimization model is proposed to solve the lack of a comprehensive consideration of user and network impacts during the handoff process in existing VHO algorithms. The Markov chain model of each base station (BS) is built to calculate a more accurate value of the network state that reflects the network performance. Then, a multi-objective optimization model is derived to maximize the value of the network state and the user data receiving rate. The multi-objective genetic algorithm NSGA-II is finally employed to turn the model into a final VHO strategy. The results of the simulation for the throughput and blocking rate of networks demonstrate that our algorithm significantly increases the system throughput and reduces the blocking rate compared to the existing VHO strategies.

With the continuous promotion of urbanization, the generation of construction and demolition waste (CDW) is increasing. The environmental problems and safety hazards caused as a result need to be resolved. In this paper, based on the system dynamics (SD) theory, the modeling, the cost, and the environmental benefit of CDW resource management under the life cycle assessment (LCA) are proposed. Specifically, we propose a combined policy derived through three variables, namely, fines, subsidies, and charges. The target is to reduce illegal dumping behavior and landfill volume and to improve the recycling volume and environmental benefits. The model is constructed with the help of the software VENSIM, and the validity and feasibility of the model are demonstrated with data from Nantong City. The results show that a single policy cannot simultaneously improve environmental benefits, illegal dumping, recycling, and landfill behavior. A combined policy combines the advantages of three single policies, fines, subsidies, and charges, which not only can effectively curb illegal dumping and landfill disposal under the premise of prioritizing environmental benefits, but can also promote the recycling of CDW. The reasonable range for the fine is 300–350 CNY/ton; the rational range for subsidies is 30–40 CNY/ton; and the flexible range for treatment charge is 40–80 CNY/ton. The model can be used for the quantitative assessment of urban CDW management costs and environmental benefits and can also provide a theoretical basis for the government.

This system is a ZigBee-to-Wi-Fi wireless gateway that implements a WSN/ZigBee seamless, wireless connectivity to WLAN. It will help ZigBee devices communicate with standard equipments via wireless medium, vice versa. Hardware system is composed of LM3S9B96, CC2520 and Wi-Fi module. Z-Stack is TI's ZigBee solution that manages network formation, protocol conversion, flow control, etc. It runs in LM3S9B96, and uses CC2520 as the transceiver. Both CC2520 and Wi-Fi module are controlled by LM3S9B96. Functional testing and performance testing prove that this system has a practical value. It can work in many scenarios, such as home automation.

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