Impact of Short-Cut SWCF Yarn on Conductivity and Electrical Heatability of Silicone–MWCNT Composites

The incorporation of MWCNTs in polymer systems up to the percolation range renders them electrically conductive. However, this conductivity is not high enough for heating applications in the low-voltage range (<24 V). The combination of nanoscaled MWCNTs with microscaled short SWCNT fibers that was investigated in this study causes an abrupt rise in the conductivity of the material by more than an order of magnitude. Silicone was used as a flexible and high-temperature-resistant matrix polymer. Conductive silicone coatings and films with SWCF contents of 1.5% to 5% and constant MWCNT contents of 3% and 5% were developed, and their electrical and thermal properties in the voltage range between 6 and 48 V were investigated. The electrical conductivity of 3% MWCNT composite materials rose with a 5% addition of SWCFs. Because of this spike in conductivity, output power of 1260 W/m2 was achieved, for example, for a 100 µm thick composite containing 3% MWCNT and 4% SWCF at 24 V with a line spacing of 20 cm. Thermal measurements show a temperature increase of 69 K under these conditions. These findings support the use of such conductive silicone composites for high-performance coatings and films for challenging and high-quality applications.

Dynamic walking characteristics and control of four-wheel mobile robot on ultra-high voltage multi-split transmission line

High-voltage lines are an important channel for power transmission, and multi-split transmission lines are the main strength of power transmission. Compared with double-wheel single-wire maintenance robots, ultra-high-voltage multi-split transmission lines and four-wheel mobile robots have a wider application range and greater demand. The maintenance of multi-split transmission lines relies on the stable walking and control of four-wheel mobile robots on heterogeneous multi-split transmission lines. However, uncertain disturbance factors such as wind load in the complex field environment cause vibration of double-split and quad-split lines. The slight change in the line spacing causes the line contact to the edge of the robot’s walking wheel, which increases the friction during the robot’s walking. It also directly hinder the movement of the robot on the multi-split transmission line, thus restricting the completion of the robot’s maintenance operation. Based on the analysis, this paper establishes a mathematical model of the external force disturbance influence on the spacing of the double-split lines. At the same time, the robot walking mechanics characteristics model under the change of the line space has been established. Three different forms of the robot walking online have been obtained through abstraction processing. A method of side friction identification based on fuzzy control has been proposed, through the online monitoring of the friction between line and edge of the walking wheel, the robot walking wheel motor walking force can be intelligently controlled in real time, and effectively avoids the “wheel-line” jam phenomenon under the external uncertain factors in the field environment. Finally, the feasibility and engineering practicability of the method have been verified through MATLAB/ADAMS simulation and field operation experiments. Therefore, the automation and intelligence level of the operation and the transmission system maintenance management has been improved.

Rendimiento de la planta de frijol caupí [Vigna unguiculata (L.) Walp] y calidad nutricional en los sistemas de cultivo intercalado de frijol caupí y sorgo

In traditional row and strip cowpea-sorghum intercropping systems, cowpea forage yield reduces significantly due to intense competition and dominance of sorghum in acquiring growth resources. This field study evaluated novel mixed strip intercropping systems of forage cowpea and sorghum having different number of crops rows arranged under different spatial arrangements. Cowpea was intercropped with sorghum in 8, 12 and 16 rows strips with row-row spacing of 30, 45 and 60 cm. In each strip, equal number of rows of cowpea and sorghum were maintained. Factorial arrangement of randomized complete block design with three replicates was used to execute the field trials during summer seasons of 2013 and 2014. Strips having 12 rows and 60 cm row-row spacing positively affected all agronomic variables of cowpea which led to maximum forage yield (22.2 and 23.7 t ha-1 during 2013 and 2014 respectively) and dry matter biomass (6.63 and 6.94 t ha-1 during 2013 and 2014 respectively). In contrast, 8-rows strips having line spacing of 30 cm outperformed other intercropping systems by yielding the maximum herbage yield and dry matter biomass of sorghum. The intercropping system comprising of 12-rows strips with 60 cm row-row spacing remained superior in recording the maximum crude protein, fats and total ash along with the minimum fiber content of cowpea. In addition, this intercropping system under rest of spatial arrangements also remained unmatched, while 16-rows strips under all planting geometries remained inferior to other intercropping systems. Thus, cowpea intercropping with sorghum in 12-rows strips having 60 cm spacing offers biologically viable solution to improve biomass and forage quality of cowpea in intercropping with sorghum.

Trajectory Planning of Robot-assisted Abrasive Cloth Wheel Polishing Blade based on Flexible Contact

Industrial robot-assisted abrasive cloth wheel (ACW) accurately polish blades is considered to be a challenging task, and it is necessary to realize the digitalization of the process. Due to the flexible contact characteristics of abrasive cloth wheel and the change of blade surface curvature, the amount of microscopic material removal and the topographical errors of the blade surface are not uniform. So the surface roughness value is larger. In this paper, considering the flexible deformation of the blade and the abrasive cloth wheel during polishing contact, the polishing contact model of the blade and the abrasive cloth wheel is established and simulated. Firstly, based on the Preston equation and Hertz contact theory, the material removal profile in the contact area of the blade and the abrasive cloth wheel is analyzed. Secondly, the step length is optimized by considering the deformation of the abrasive cloth wheel in thedirection, and the line spacing is optimized by considering the material removal uniformity in thedirection. The NURBS curve is used to extract the blade polishing area curve and generate the polishing trajectory data points. Then, two methods of rigid trajectory planning and flexible adaptive trajectory planning of abrasive cloth wheel are simulated and analyzed by offline programming software. Finally, experiments were carried out on a four-station wheel changing polishing platform. Simulation and experiments results show that the proposed flexible adaptive trajectory planning method can make the surface roughness of the convex and the concave, the surface roughness of the leading and trailing edge, the total polishing efficiency increased by about 9.4%.

Using text as a native speckle pattern in digital image correlation

In certain applications, native surface patterns can be used in place of speckle patterns in digital image correlation (DIC). This paper explores the feasibility of using text as a native speckle pattern in DIC. Five text speckle patterns are tested in three different scenarios: a rigid body translation test, a rigid body rotation test, and an out of plane bending test. The patterns are benchmarked against a sixth, random speckle pattern applied using traditional DIC speckling methods. Rigid body translation tests are additionally performed on text patterns with varying font types and line spacings. In general, text patterns have good contrast, but low density as line spacing increases. Measurement uncertainty for the text patterns was comparable to measurement uncertainty in the random speckle pattern. Results from these tests show that while text patterns cannot be expected to perform better than a traditional DIC speckle pattern, text patterns can be effective speckle patterns in situations where already present on a specimen and applying a traditional speckle pattern is difficult.

The process of magnetic flux penetration into superconductors

In the present paper the magnetic flux penetration dynamics of type-II superconductors in the flux creep regime is studied by analytically solving the nonlinear diffusion equation for the magnetic flux induction, assuming that an applied field parallel to the surface of the sample and using a power-law dependence of the differential resistivity on the magnetic field induction. An exact solution of nonlinear diffusion equation for the magnetic induction B(r, t) is obtained by using a well-known self-similar technique. We study the problem in the framework of a macroscopic approach, in which all length scales are larger than the flux-line spacing; thus, the superconductor is considered as a uniform medium.

Cross-Phase Modulation Based Ultra-Flat 90-Line Optical Frequency Comb Generation

This paper proposed an approach to design an evenly spaced, 1.8 THz spectrally broad and 1.6 dB flat optical frequency comb (OFC) by exploiting the cross-phase modulation in highly nonlinear fiber. The OFC is realized by controlling the phase of the signals in two parallelly placed highly nonlinear fibers. The frequency and line spacing of the OFC can be tuned by simply varying the periodicity and central wavelength of input electrical and optical signal, respectively.