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Water diffusion significantly contributes to abnormal temperature rise in composite insulators. At the same time, the material performance defect caused by the composite insulator production process can further increase moisture intrusion. To propose optimized heating measures for composite insulators from the material itself, this paper conducts research on the ingredient process of composite insulator sheath and the production process of composite insulator core rods, respectively. We establish the water absorption model of aluminium hydroxide particles and the penetration model of epoxy resin. Then we identified that the flame retardant particle size is a factor that affects the water absorption of the sheath, while epoxy resin liquid viscosity and fibre volume fraction are factors that affect the porosity of the core rod in the process. Water absorption experiments are conducted to verify the positive correlation between the particle size of flame retardant and the saturated water absorption rate of the sheath. Our porosity testing has confirmed that low-viscosity liquids and high-fibre volume fraction can reduce the porosity of the core rod. Based on these findings, we propose heat generation optimization measures for the sheath and core rod from a process perspective.

This paper deals with the jerk-minimization trajectory planning of robotic arms, in order to meet the increasing demands of the practical tasks that require fast motion planning of highly dynamic real-time movements for the task execution, by means of polynomial curve-based trajectory design. By solving a constrained quadratic optimization problem, the trajectory planning is optimized by minimizing the jerk of the robot end-effector. Experimental pick-and-place operations are carried out in comparison with the trajectory design without optimization and non-uniform rational B-spline (NURBS) curve, respectively, from which the results show the trajectory optimization is applicable in real-time trajectory planning. Both the numerical simulation and experimental implementations validate the presented approach of optimizing trajectory planning and show the effectiveness.

Here, we report a series of two-dimensional lanthanide metal-organic frameworks Ln-DBTPA (where DBTPA = 2,5-dibromoterephthalic acid and Ln = Tb (

In order to solve the problem of waste heat collection from energy consumption, a thermal energy generation device combining shape memory alloy and piezoelectric materials has been designed. The shape memory alloy is heated and deformed to drive the drive wheel continuously, and the impact wheel is deformed against the piezoelectric cantilever beam during the rotation of the drive wheel to generate electricity. In this paper, the impact force generated by the impact wheel and the output voltage of the piezoelectric cantilever beam during the rotation process are given. Finally, the experimental test shows that the larger the radius of the drive wheel, the lower the impact force of the wheel and the lower the output voltage of the piezoelectric cantilever beam; the larger the diameter of the shape memory alloy wire, the higher the impact force of the wheel and the higher the output voltage of the piezoelectric cantilever beam; the more teeth of the drive wheel, the higher the impact frequency of the piezoelectric cantilever beam and the higher the output voltage. The maximum output voltage of the thermoelectric converter is 14.2 V, when the drive wheel radius is 13 mm, the shape memory alloy wire diameter is 1 mm and the number of impact wheel teeth is 6. The new structural design provides a new structural model for waste heat recovery and thermal energy generation technology. The new structural design provides a new approach and idea for waste heat recovery and thermal energy generation technology.

The holes in composite insulator rods are a type of quality defects. However, not all holes can be identified by the dye penetration test according to existing standards and some holes can cause abnormal heating of the composite insulator during operation. Micro‐computed tomography is used to study the structure of these holes. Based on the pore structure, the holes are classified as dependent or independent. The dependent hole is formed by several interconnected adjacent pores and the overlong equivalent penetration path makes it cannot be effectively identified by the standard dye penetration test. Considering the structure of the dependent hole, ethanol gas was used to increase the effectiveness of the dye penetration test. The experimental results show that the detection rate of dependent holes is approximately 80% as the ethanol concentration is close to saturation, and the porosity can be inferred based on the number of penetration points.

In recent years, the quantity and proportion of heating defects have increased significantly with more composite insulators used in transmission lines and deterioration of early composite insulators. End heating is the main characteristic of this kind of defect in high‐temperature and high‐humidity areas. In this paper, microstructures of the housing material were observed through scanning electron microscopy and the key factors leading to temperature rise were studied through water absorption and power loss experiments. The results show that polarisation loss is the main cause of temperature rise and power loss increases exponentially with higher electric field intensity. The microporous structures of the housing material not only enhance the moisture absorption effect, but also affect the uniform distribution of the electric field. Due to the concentration of the local electric fields at high‐voltage end, the effect of porosity on temperature rise is more significant. By adjusting the shielding depth (i.e. installation height) of grading ring or adding a racetrack ring to restrain electric field intensity at high‐voltage end of composite insulator, the temperature rise in high‐humidity areas can be effectively reduced.

This paper investigates a feasible nondestructive method for micron-sized kissing defects in the composite insulators, which are commonly utilized in ultra-high voltage (UHV) power grid. In this paper, cylindrical adhesive contact model was established to describe the obvious distortion of ultrasound propagation caused by kissing defects on the polymeric interface of composite insulators. The ultrasonic nonlinearity parameter was measured for each of the kissing defective and intact specimens. Moreover, the theoretical analysis has been proved by the test results on the kissing defective samples, which indicates that the 0.7 μm kissing defects existed in the composite insulators could be successfully recognized by the nonlinear ultrasonic methods and the nonlinearity is reduced by interface roughness.

Multiple Hypothesis Solution Separation (MHSS) is the baseline algorithm for Advanced Receiver Autonomous Integrity Monitoring (ARAIM), and it detects faults by comparing the test statistic with a threshold. However, the cuboid threshold structure of the MHSS fault monitoring baseline algorithm lacks omnidirectionality, which leads to low conformity between the threshold and the spatial distribution of the test statistic and to low fault monitoring accuracy. To resolve these problems, we analyzed the distribution of a test statistic for single-, double-, and triple-fault hypotheses. By extracting the eigenvectors and eigenvalues of the solution separating variance, we designed an omnidirectional threshold structure. The simulation verifies the effectiveness of the fault detection method by detecting faults from noise. The results show that the proposed method is more exact, stable, and applicable than the MHSS fault detection baseline.

The interface is the weakness of composite insulators. As the interface bonding fails, the uniform distribution of electric field will be affected, which accelerates the aging of composite insulators and affects the safe operation of transmission lines. Because of the stress between the sheath and the rod, the air gap at the interface is generally less than 10 ţm and there is extrusion contact in some areas. Therefore, conventional nondestructive testing technology based on refraction and reflection principle cannot effectively identify the faulty insulators in the initial stage of bonding failure. Based on the constitutive model of the interface of composite insulators, the friction force of the interface after bonding failure introduces more nonlinearity in mechanical properties than hydrogen bond under well bonding condition. The numerical results show that under the influence of the nonlinear constitutive relation, the higher harmonic components in the spectrum will increase significantly. The experimental results of plate and insulator samples confirm the validity of numerical calculation. Based on the normalized nonlinearity coefficient, the interface state of composite insulators at the initial stage of bonding failure can be effectively identified.

Nowadays, deep learning has been widely used in various fields, and great breakthroughs have been made in computer vision, speech recognition and natural language processing. Based on the deep learning algorithm, this paper studies the general optimization technology of OpenCL based on FPGA in detail, and puts forward a targeted hardware design scheme, which has the characteristics of high performance, low power consumption and programmability. By analyzing the algorithm of forward calculation and reverse calculation in convolutional neural network, the hardware acceleration module is designed. Compared with CPU, GPU and other platforms, FPGA has obvious advantages in power consumption, which proves that the scheme proposed in this paper has good feasibility and accuracy.

Composite insulators have been widely used in EHV and UHV transmission lines due to their excellent anti-pollution flashover performance, high strength and easy installation. As an important part of composite insulator, glass fiber reinforced polymer rod needs to bear the main mechanical load and is also the key to insulation performance. In recent years, although the brittle fracture of rod has been effectively solved, the abnormal temperature rise and decay-like fracture caused by rod defects still affect the safe operation of transmission lines seriously. In this paper, the microstructure of the rod is studied by improved dye penetration test and three-dimensional scanning, and the influence of microstructure difference is studied by water absorption and loss power experiments. The results show that moisture penetration caused by large porosity and penetration channel is the key factor to increase the loss power of rod. By improving the performance requirements of rod, the heating and decay-like fracture of composite insulator could be avoided to some extent.

International audience; This paper presents a four-limb parallel Schönflies motion generator for the pick-and-place application, whose end-effector is composed of a planetary gear train as the amplification mechanism to realize the full-circle rotation. The kinematic aspects including the workspace, dexterity and singularity are analyzed and evaluated. The singular configurations and the singularity loci are identified both graphically and numerically, which shows that the singular configurations of the manipulator can be avoided by keeping all the limbs working in a prescribed working mode together with the end-effector rotation in a clockwise direction from the neutral orientation. Moreover, the dexterity evaluation is carried out to depict the workspace quality and dexterous working envelope. It turns out that the proposed robot admits a super-ellipsoidal workspace with the full-circle rotation of the end-effector, suitable for pick-and-place operations. Finally, robot dynamics is considered to select the actuators.

Due to excellent anti-pollution flashover performance, a composite insulator has become the most frequently and widely used insulator product in transmission lines . Sheath hydrophobicity is the core factor that determines the anti-pollution flashover performance of the composite insulator. To study the change rule of insulator sheath hydrophobicity under the long-term operation condition, more than 390 samples produced by the same manufacturer that had operated for 3–22 years were extracted from the adjacent lines to eliminate the impact of the running environment and manufacturer formula. To study the reasons for hydrophobic fluctuations, surface energy tests and Fourier transform infrared spectroscopy tests were conducted on the superficial layer materials based on a two-droplet method. The change rule of the material physical and chemical properties with operation time was obtained. Next, the relationship between the surface microstructure of the material and operation time was determined by laser scanning confocal microscopy and scanning electron microscopy . Finally, based on the analysis results of surface energy and surface topography, the physical model of shed material hydrophobic variation in the operation process was obtained.

As an important part of composite insulator, glass fiber reinforced polymer (GRP) rod needs to bear the main mechanical and keep certain insulation performance. The void in the material is key factor to the performance of GRP rod. The void with larger size could affect the electric field distribution significantly and lead to the “Lantern-like” heating. In this paper, the structure of void in GRP rod is studied by 3D X-ray microscope. It is found that the void dimensions in the GRP rod is generally less than 300μm, but the interconnection of linear hole makes the length of the void increase significantly. For the GRP rod with high porosity, the length of connection hole is hard to be detected directly by the existing technology, but it could be calculated based on the diameter of the hole. Based on the calculation method, the dimensions of void in GRP rod could be inspected by the observation of section using optical microscope.

The effect of chelating agents on the decolorization of Reactive Green 19 (RG19) through Fe0 activated persulfate (PS/Fe0) process was investigated. Though other previous studies reported that chelating agent can enhance the degradation of organic contaminant in Fenton-like system, our finding showed that the presence of chelating agents would chelate free Fe2+ and minimize free Fe2+ concentration, which resulted in the retardation of RG19 decolorization. RG19 decolorization decreased to 7%, 21%, and 15% in the presence of sodium citrate, sodium EDTA, and sodium oxalate, compared with control test (without chelating agent, 99%) within 10 min. The degradation efficiencies decreased with increasing chelating agent concentrations because of complex formation with Fe2+. Higher PS concentration, Fe0 dosage, and temperature had an obvious enhancement for RG19 decolorization efficiency. Elucidation of RG19 containing sodium EDTA degradation pathways indicated that PS/Fe0 process could degrade RG19 to carboxylic acids and inorganic salts efficiently. The presence of sodium EDTA had no influence on by-products, and EDTA just played a chelating agent function for chelating Fe ions.

This paper deals with motion planning of a 5-DOF anthropomorphic robotic arm. The CAD model of the robot is built and converted into a URDF file for the simulation with the ROS platform. Sequentially, the motion planning of the manipulator is completed through the MoveIt! Package. The motion process is observed in RViz, with the planned result being transmitted to the servo controller to drive the real robotic arm to reach to the target point. Moreover, the extraction and matching of key feature points based on SIFT algorithm is studied for object detection to obtain the coordinates of the targeted object, in order to realize the pick-and-place operation for the material handling.

Composite insulators are widely used in high voltage transmission lines in coast and polluted areas due to excellent pollution flashover resistance, high strength and convenient installation and maintenance. While there are still various kinds of defects such as abnormal temperature rise, aging of materials even fracture in the existing composite insulators which have drawn the close attention of the operation and maintenance department of power grid. In order to realize the basic performance of new composite insulator products in China, specimens from major manufacturers of composite insulators are sampled for mechanical, electrical and physical and chemical testing. The test results show that the composite insulator products meet the requirements overall, but a few of them have micro-interface and macro-interface defects which may cause local heating even fracture under high humidity conditions. At the same time, the raw materials of composite insulator housing from different manufacturers is quite different, which has certain influence on the service life of composite insulator.

Interface is the weak point of composite material. The adhesive quality will affect the life span of equipment and performance of electrical insulation system directly. Therefore, it is important to ensure adhesive quality of the interface in composite insulation equipment for the security of the whole power grid. Due to the scalability of silicone rubber and the cylinder structure of external insulation equipment, the thickness of the air layer in defective interface is less than 100$\mu$m. This kind of defect is called weak adhesion defect in this manuscript. It cannot be effectively identified by existing nondestructive testing (NDT) methods. Ultrasonic signal is more sensitive to the presence of the air layer because of huge difference in acoustic impedance. The bonding samples of SIR and FRP were detected by 1MHz ultrasonic signal in the laboratory. Based on the spring equivalent model, the nonlinear constitutive relation of weak adhesion defect was obtained. Preliminary results of the nonlinear analysis show that the amplitude of fundamental frequency signal in the echo signal is reduced while the amplitude of high-order harmonic signal is enhanced when the interface adhesive strength of composite decreased. In addition, the nonlinear coefficient increases significantly.

Super-hydrophobic surfaces is a probable method to solve the icing and contamination problems in the out-door insulation. Considering the large amount of the out-door insulation equipment, we are in urgent need of a cheap and convenient constructing method. In this paper, a super-hydrophobic surface constructing method has been studied in which the sheath of the composite insulators has been used as the raw material. With this new method, two problems, the constructing of the super-hydrophobic surfaces and the recycling of the composite insulators which are difficult to degradation and harmful to the environment, have been resolved at the same time. Firstly, the pyrolysis method was used to simulate the combustion process of silicone rubber housing, and FTIR, TGA-MS, XPS and LPSA were used to analyze the formation of solid products and gas products during the pyrolysis of silicone rubber. According to the analysis of the physical and chemical properties of the products, the best experimental parameters have obtained. Secondly, A super-hydrophobic surface has been constructed on the surface of an originally hydrophilic material, glass, which is commonly used in the out-door insulation. Finally, the performance of the super-hydrophobic coating has been analyzed, and its static contact angle and rolling angle have been measured, as well as the anti-contamination flash performance. The experimental results show that the surface constructing method based on the recycling of the composite insulators could get a super-hydrophobic surface which could slow done the icing process, and improve the contamination flashover performance as well.

Interface is the weak point of composite insulator. The Interface defects in composite insulators may lead to heating, aging acceleration even fracture accidents. These will have a serious effect on the safe operation of transmission lines. Therefore, it is significant to improve the level of safeguard of the power grid by periodically detecting the composite insulators and replacing the composite insulators with hidden trouble. Compared with the traditional infrared detection, taking advantages of differences in propagation processes of pulsed heat flux has better initiative and applicability and the measurement speed is fast and the precision is high. In this paper, the propagation law of pulsed heat flux has been studied with the simulation plate model, and difference of temperature between defective and reference area has been analyzed when the thermal excitation meet the Dirac function. Secondly, Plate samples and insulators with interfacial defects have been produced, and the defects in plate samples could be easily distinguished by the radiation quantity immediately. Finally, to increase the resolution of this method, according to the characteristic of the thermal wave obtained by the simulation and tests, the derivate of the data has been further processed in the Logarithmic coordinate system, and the difference between defective area and reference area has approximately enlarged 7 times and 1 mm defect could be distinguished.

Usually, the air gap will appear inside the composite insulators and it will lead to serious accident. In order to detect these internal defects in composite insulators operated in the transmission lines, a new non-destructive technique has been proposed. In the study, the mathematical analysis model of the composite insulators inner defects, which is about heat diffusion, has been build. The model helps to analyze the propagation process of heat loss and judge the structure and defects under the surface. Compared with traditional detection methods and other non-destructive techniques, the technique mentioned above has many advantages In the study, air defects of composite insulators have been made artificially. Firstly, the artificially fabricated samples are tested by flash thermography, and this method shows a good performance to figure out the structure or defects under the surface. Compared the effect of different excitation between flash and hair drier, the artificially samples have a better performance after heating by flash. So the flash excitation is better. After testing by different pollution on the surface, it can be concluded that different pollution don't have much influence on figuring out the structure or defect under the surface, only have some influence on heat diffusion. Then the defective composite insulators from work site are detected and the image of defect is clear. This new active thermography system can be detected quickly, efficiently and accurately, ignoring the influence of different pollution and other environmental restrictions. So it will have a broad prospect of figuring out the defeats and structure in composite insulators even other styles of insulators.

The effect of chelating agents on the decolorization of Reactive Green 19 (RG19) through Fe

A new graphene-based electrochemical biosensor was constructed and applied for the simple, rapid and highly selective determination of glucose. The modified glassy carbon electrode (GCE) was prepared using dopamine (DA) as a reducing agent for graphene oxide (GO) and as a capping agent to stabilize and coat the resulting reduced graphene oxide (RGO) surface as it can polymerize to form polydopamine (PDA). PDA-RGO composites were dropped onto a glassy carbon electrode surface, and glucose oxidase (GOx) was immobilized on the surface of the composites by Michael addition. Finally, Pt nanoparticles (PtNPs) were electrodeposited on the modified electrode. Such modified electrodes (denoted as GCE/PDA-RGO/GOx/PtNPs) were characterized by UV-visible spectroscopy, atomic force microscopy, X-ray power diffractometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Electrochemical behaviors were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The fabricated biosensor exhibited a high sensitivity of 33 μA mM−1 cm−2 over a wide linear range of 0.2 mM to 1 mM, good stability, excellent repeatability, and a detection limit of 0.10 mM.

Plasma-cavity ringdown spectroscopy is a powerful absorption technique for analytical measurement. It combines the inherent advantages of high sensitivity, absolute measurement, and relative insensitivity to light source intensity fluctuations of the cavity ringdown technique with use of plasma as an atomization/ionization source. In this review, we briefly describe the background and principles of plasma-cavity ringdown spectroscopy(CRDS) technology, the instrumental components, and various applications. The significant developments of the plasma sources, lasers, and cavity optics are illustrated. Analytical applications of plasma-CRDS for elemental detection and isotopic measurement in atomic spectrometry are outlined in this review. Plasma-CRDS is shown to have a promising future for various analytical applications, while some further efforts are still needed in fields such as cavity design, plasma source design, instrumental improvement and integration, as well as potential applications in radical and molecular measurements.

Cancer diagnosis and treatment are of great interest due to the high death rate of cancer. To improve the cure rates of cancer, a diagnostic tool which can detect and treat cancer at initial stages is great needed. Laser-induced fluorescence (LIF) is an adequate analytical technique with advantages of high sensitivity, low sample consumption, short testing time, and suitable for in situ testing. Therefore, it has become one of the most widely used spectroscopic methods for cancer in vivo diagnosis in recent years. This review mainly focuses on the applications of in vivo LIF to distinguish premalignant, malignant from normal tissues in a variety of organ systems, such as lung breast, colon, cervix, esophagus, and bronchus. The potential influence factors for cancer diagnostics and the subsequent suitability of the method to different applications are well discussed. Meanwhile, the technical merits and weaknesses of the LIF technology for cancer diagnosis are also evaluated. Furthermore, different exogenous fluorophores, endogenous fluorophores, and fluorophores synthesized in the tissue are compared on their active principle and effect contrast. The technical potentials of LIF for further development and future applications are also presented as well in this review.

In this paper, we propose a new framework for facial expression classification. This framework utilizes random forest as the classifier based on the features extracted from improved principal component analysis (PCA). Traditional PCA has two drawbacks: it is difficult to estimate the covariance matrix, and it is computational prohibitive to get the eigenvectors. In order to solve the two problems, we adopt an improved PCA to extract the features and uses the random forest algorithm as the classifier. The experiments are conducted based on the JAFFE facial expressions library, and are compared with the support vector machine (SVM) classifier. Theoretical analysis and experimental results show that the facial expression recognition system of random forest based on improved PCA extracting feature, whether in terms of facial expression recognition rate or running speed, has shown significant improvement.

Beidou navigation satellite system (BDS) has provided open services for the most part of the Asia-Pacific region and plans to provide global service in 2020. In the future, it is necessary for BDS to support ARAIM. As an important parameter of ARAIM, the maximum nominal bias (Bnom) of BDS need to be determined. This paper aims to estimate the impact of nominal biases on ARAIM user performance of BDS. In particular, we focus on the signal deformation and the satellite group delay of BDS signal.