Development of a Control System for Double-Pendulum Active Spray Boom Suspension Based on PSO and Fuzzy PID

During the operation of boom sprayers in the field, it is crucial to ensure that the entire boom is maintained at an optimal height relative to the ground or crop canopy. Active suspension is usually used to adjust the height. A control system for double-pendulum active suspension was developed in this paper. The control system consisted of a main control node, two distance measurement nodes, a vehicle inclination detection node, and an execution node. Communication between nodes was carried out using a CAN bus. The hardware was selected, and the interface circuits of the sensors and the actuator were designed. The transfer functions of the active suspension and electric linear actuator were established. In order to enhance the efficiency of the control system, the particle swarm optimization (PSO) algorithm was employed to optimize the initial parameters of the fuzzy PID controller. The simulation results demonstrated that the PSO-based fuzzy PID controller exhibited improvements in terms of reduced overshoot and decreased settling time when compared to conventional PID and fuzzy PID controllers. The experimental results showed that the active suspension system equipped with the control system could effectively isolate high-frequency disturbances and follow low-frequency ground undulations, meeting the operational requirements

Ultrastretchable carbon nanotube composite electrodes for flexible lithium-ion batteries

© 2018 The Royal Society of Chemistry. Ultra-stretchable carbon nanotube (CNT) composite electrodes for lithium-ion batteries are fabricated by coating CNT films and active material powders on biaxially pre-strained polydimethylsiloxane (PDMS) substrates. The wrinkled structures that form during the pre-straining and release process extend along the strain axis to protect the CNT composite structures from fracture. The CNT composites demonstrate excellent stability and high durability with resistance increase of less than 12% after 2000 cycles at 150% strain. Both CNT/Li4Ti5O12 (LTO) anodes and CNT/Li(Ni1/3Co1/3Mn1/3)O2 (NCM) cathodes maintain excellent electrochemical properties at cyclic 150% strain in different axes. The full lithium-ion battery consisting of the stretchable CNT/LTO anode and CNT/NCM cathode is able to withstand 150% strain in different axes without large decreases in performance. Stretchable batteries fabricated by the scalable, highly efficient, and low-cost biaxial pre-strain process with excellent durability and electrochemical properties will have potential applications in flexible devices

Effect of an Auxiliary Plate on Passive Heat Dissipation of Carbon Nanotube-Based Materials

Carbon nanotubes (CNTs) and other related CNT-based materials with a high thermal conductivity can be used as promising heat dissipation materials. Meanwhile, the miniaturization and high functionality of portable electronics, such as laptops and mobile phones, are achieved at the cost of overheating the high power-density components. The heat removal for hot spots occurring in a relatively narrow space requires simple and effective cooling methods. Here, an auxiliary passive cooling approach by the aid of a flat plate (aluminum–magnesium alloy) is investigated to accommodate heat dissipation in a narrow space. The cooling efficiency can be raised to 43.5%. The cooling performance of several CNT-based samples is compared under such circumstances. Heat dissipation analyses show that, when there is a nearby plate for cooling assistance, the heat radiation is weakened and natural convection is largely improved. Thus, improving heat radiation by increasing emissivity without reducing natural convection can effectively enhance the cooling performance. Moreover, the decoration of an auxiliary cooling plate with sprayed CNTs can further improve the cooling performance of the entire setup

State-Based Technical Condition Assessment and Prediction of Concrete Box Girder Bridges

The technical condition of bridges has become a crucial issue for organizing the maintenance and repairs in bridge management systems. It is of great practical engineering significance to construct an effective model for predicting the technical condition degradation of the bridge through the use of the historical inspection data. Based on the semi-Markov random process, this paper proposes a useful deterioration prediction model for bridges in the highway network. From the historical inspection data of the prefabricated concrete box girder bridges, the degradation curves of technical condition rating are obtained. The effect of bridge length on degradation rate of the prefabricated concrete box girder bridges is analyzed. According to the Weibull distribution parameters of different condition grades, the technical state degradation models for a bridge group and an individual bridge are proposed to predict the performance of the overall bridge and superstructure of the bridge. The results show that with the increase in bridge length, the degradation rate of bridge technical condition increases. The degradation rate of the technical condition of the superstructure is faster than that of the overall bridge. The proposed semi-Markov stochastic degradation model for the bridge group can not only predict the different condition ratings of the bridges at any time, but also predict the future deterioration trend of an individual bridge under any ratings

Stable and Biocompatible Colloidal Dispersions of Superparamagnetic Iron Oxide Nanoparticles with Minimum Aggregation for Biomedical Applications

In this article, a simple and scalable method for preparing well-defined and highly stable colloidal dispersions of superparamagnetic iron oxide nanoparticles (IONPs) is reported. The IONPs with narrow size distribution were synthesized by polyol process. Nonhazardous sodium tripolyphosphate (STPP) was immobilized on the surface of IONPs via effective ligand exchange in aqueous phase. Then the STPP-capped IONPs were purified by tangential flow ultrafitration. The polyanionic nature of STPP and its strong coordination capability to iron oxide warrant the IONPs long-term colloidal stability even in phosphate-buffer saline. Because the ligand exchange and purification process did not involve repeated precipitation by organic solvents, the unwanted irreversible aggregation and organic impurities were avoided to the utmost extent. The absence of aggregation renders the IONPs well-defined magnetic behaviors and optimized relaxometric properties for <i>T</i>₁-weighted magnetic resonance imaging. The in vitro cytotoxicity test suggests that the STPP-capped IONPs possess little toxicity. In vivo MRI experiment carried out with a mouse model demonstrates the excellent <i>T</i>₁-weighted MR contrast enhancement capability of the IONPs. This new kind of IONPs is expected to be applicable in various biomedical applications

Porous TiO₂ Nanoparticles Derived from Titanium Metal–Organic Framework and Its Improved Electrorheological Performance

A simple method for synthesis of porous TiO₂ nanoparticles was developed via a two-step route using titanium metal–organic framework (MOF) as a precursor, in which MOFs were first prepared by a cetyltrimethylammonium bromide (CTAB) assisted solvothermal method and then calcined in air at 500 °C. After pyrolysis of precursor MOFs, the anatase TiO₂ inherited the porosity of precursor MOF and possessed a large surface area and uniform pore distribution, which was subsequently adopted as an electrorheological (ER) material by dispersing in silicone oil. ER activities of MOFs and porous TiO₂ based suspensions under the applied electric fields were investigated in a controlled shear rate (CSR) mode. In contrast to MOFs based ER fluids, the suspension of porous TiO₂ exhibited a higher ER efficiency and lower leakage current. Furthermore, the improvement of dielectric properties was found to be responsible for the enhanced ER activity through an investigation of dielectric spectrum