The accurate detection of insulator profile of mine transmission line is the basis and premise of mine intelligent UAV (unmanned aerial vehicle) inspection, but it has not been effectively solved. In this paper, the mathematical model of traditional edge detection operator is first derivative operator: Robert operator, Prewitt operator, Sobel operator, and operators whose mathematical model is second derivative Laplacian operator, LOG operator, Canny operator and so on are studied comprehensively. These algorithms are applied to the insulator profile detection of transmission lines, and the experimental results are analyzed and compared.
This paper reports a more complete description of the design process of the Center Support Quadruple Mass Gyroscope (CSQMG), a gyro expected to provide breakthrough performance for flat structures. The operation of the CSQMG is based on four lumped masses in a circumferential symmetric distribution, oscillating in anti-phase motion, and providing differential signal extraction. With its 4-fold symmetrical axes pattern, the CSQMG achieves a similar operation mode to Hemispherical Resonant Gyroscopes (HRGs). Compared to the conventional flat design, four Y-shaped coupling beams are used in this new pattern in order to adjust mode distribution and enhance the synchronization mechanism of operation modes. For the purpose of obtaining the optimal design of the CSQMG, a kind of applicative optimization flow is developed with a comprehensive derivation of the operation mode coordination, the pseudo mode inhibition, and the lumped mass twisting motion elimination. The experimental characterization of the CSQMG was performed at room temperature, and the center operation frequency is 6.8 kHz after tuning. Experiments show an Allan variance stability 0.12°/h (@100 s) and a white noise level about 0.72°/h/√Hz, which means that the CSQMG possesses great potential to achieve navigation grade performance.
Given a one-dimensional graph G such that any two consecutive nodes are unit distance away, and such that the minimum number of links between any two nodes (the diameter of G) is O(log n), we prove an Ω(n log n/log log n) lower bound on the sum of lengths of all the edges (i.e., the weight of G). The problem is a variant of the widely studied partial sum problem. This in turn provides a lower bound on Euclidean spanner graphs with small diameter and low weight, showing that the upper bound from [1] is almost tight.
Conventional solid reinforced concrete (RC) beams were modified to slotted beams for consideration as thermal insulation structural components. The slotted beam consisted of an outer and an inner beam, respectively, with a slot located near the middle of the beam along its width direction for filling thermal insulation material. Flexural and thermal behavior of the slotted beams were investigated. Three RC reference solid beams and six slotted beams were fabricated and tested under four-point bending tests. The test results indicated that the failure mode of both slotted beams and the solid beams was flexural failure. However, the damage process of the slotted beams was different from that of the solid beams at the final loading stage. The moment curvature analysis indicated that the tensile reinforcement ratio of the outer and inner beams had an important effect on the flexural behavior, especially the ductility of the slotted beams. Thermal study indicated that the heat transfer coefficient of the slotted beam was greatly reduced and the thermal inertia factor increased a lot, compared with the solid beam. In addition, FE simulation results showed that a new frame structure using slotted beams exhibited obvious and attractive thermal insulation property.
To make lattice structures have both load-bearing and energy absorption characteristics to protect the safety of personnel and equipment in the collision, this paper proposes a multi-objective topology optimisation method for the design of lattice structures with negative Poisson's ratio. The energy absorption and load-bearing characteristics of the lattice structure are characterised by negative Poisson's ratio and stiffness, respectively. A topology optimisation model is established to maximise the stiffness and negative Poisson's ratio of the lattice structure. The design optimisation of microscopic material is conducted by the energy homogenisation method. A modified optimality criteria method is employed to update design variables. The energy absorption and load-bearing characteristics of the optimised structure are tested and analysed by finite element simulation and compression experiment, respectively. The results show that the optimised lattice structure has both energy absorption and load-bearing characteristics. In general, the proposed method can provide a feasible reference for the topology optimisation design of anti-collision structures.
This paper analyzes the variation laws of the unconfined compressive strength and modulus of deformation of steel fiber reinforced soil-cement through different factors in laboratory experiments,providing a guidance to the application of the steel fiber reinforced soil-cement.
This paper reports a multi-order system dynamic model of the novel planar gyro - Center Support Quadruple Mass Gyro (CSQMG) with an application of dynamic analysis. Compared with the dual-mass resonance system, a resonator with quadruple masses possessing 12 degree of freedom (DOF) is more complicated, and so is the error analysis. As a consequence, the lumped parameter model in a generalized coordinate is realized by regarding the N-shaped beam as two springs of the in-plane quadrature directions and simplifying the Y-shaped beam as the combination of a lever and a torsional spring. With the help of this new model, all of the eight planar natural vibration modes in the CSQMG can be calculated precisely. Comparing to the Finite Element Method (FEM) simulation and experimental measurement, the analytical natural frequencies basing on the simplified model show a maximum error of less than 1.09%, which means the multi-order system model can be applied to the system parameter identification in the future work.
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