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In textile factories, the most typical warp-knitted fabric defects include point defects, holes, and color differences. Traditional manual inspection methods are inefficient for detecting these defects. Existing intelligent inspection systems often have a single function. Factories require a real-time inspection system that can detect common defects and color difference. The YOLO (you only look once) neural network is faster than the two-stage neural network and has lower hardware requirements. The system’s color difference detection algorithm compares the color difference between the standard image and the image to be measured and records where the color difference value is exceeded. Finally, the comparison of the factory application proves that the designed system has good real-time performance and accuracy and can meet the fabric inspection requirements of warp-knitted fabric factories.

In this paper, trajectory control of arbitrary shape mandrel in three-dimensional circular braiding is studied. To obtain accurate trajectory, offset of mandrel is predicted and compensated for trajectory of mandrel. Firstly, the equation of the force of all yarns on three-dimensional mandrel is given. Then offset of mandrel in single layer braiding machine is analyzed via finite element software. Learning these data via back propagation neural network algorithm, offset of mandrel at each moment is derived. The trajectory generation of three-dimensional mandrel based on offset compensation by roll pitch yaw transformation is given. Lastly, braiding angle for the mandrel is analyzed theoretically. In the practical engineering, this method is proven to effectively reduce the error of braiding angle and helpful for the precise control of the trajectory of arbitrary shape mandrel.

In this paper, the carrier arrangement for manufacturing fabrics with a symmetrical cross-section using multi-layer interlocking braiding technology based on square rotary braiding is studied. To obtain a suitable arrangement, the paper defines a matrix to describe the state of each slot of the horn gears. The possible types of transfer positions are analyzed, and the rules of arrangement are made. A mathematical model is established to determine the possible carrier positions. Using the model, the carrier arrangements for I-section and C-section preforms are obtained. This model is helpful in solving the carrier arrangement for all types of fabrics with symmetrical cross-sections in engineering applications.

Multipartite quantum system is complex. Characterizing the relations among the three bipartite reduced density operators $\rho_{AB}$, $\rho_{AC}$ and $\rho_{BC}$ of a tripartite state $\rho_{ABC}$ has been an open problem in quantum information. One of such relations has been reduced by [Cadney et al, LAA. 452, 153, 2014] to a conjectured inequality in terms of matrix rank, namely $r(\rho_{AB}) \cdot r(\rho_{AC})\ge r(\rho_{BC})$ for any $\rho_{ABC}$. It is denoted as open problem $41$ in the website "Open quantum problems-IQOQI Vienna". We prove the inequality, and thus establish a complete picture of the four-party linear inequalities in terms of the $0$-entropy. Our proof is based on the construction of a novel canonical form of bipartite matrices under local equivalence. We apply our result to the marginal problem and the extension of inequalities in the multipartite systems, as well as the condition when the inequality is saturated., Comment: 20 pages, 1 figure

In this paper, the feasibility of applying ultrasonic technology to quantitative analysis of cotton and polyester blended fabrics by the chemical dissolution method is explored. Four varieties of blends with different cotton contents were employed and dissolved in sulfuric acid solution with ultrasound assistance. Although three different frequencies: 20, 28 and 40 kHz were adopted, the experimental results indicate that there is no difference between them. For some fabrics that cannot be untwisted into yarns, ultrasonic technology has good experimental results while only needing a fabric form prepared from a small, long strip. By comparison with the traditional mechanical oscillation method stated in ISO 1833-11:2006, the more meaningful role of ultrasonic lies in the fact that the experimental time and usage of solvent can be reduced by half, which is in agreement with resource savings and environmental protection. Broadly speaking, the study demonstrated that ultrasound assisted chemical dissolution for the quantitative analysis of cotton and polyester blended fabric is feasible.

The purpose of our research is to explore the effect of ultrasound applied on the quantitative analysis of wool in blended fabric by chemical reaction with a mechanical device. One cylindrical container for blended fabric for the whole process is designed, and detailed observations are made of the step of wool-dissolving assisted by ultrasound. A ventilation hole is essential for the fabric container or else the solvent will be unable to transcend in and out of the fabric container smoothly. For fabrics that cannot be untwisted into yarns, shredding into strips is a reasonable alternative. The fabric piece in the fabric container weighed 0.5 g and the appropriate time for dissolving was 40 minutes. As compared to the traditional manual method, dissolving in the fabric container assisted by ultrasound is equivalent, but is more convenient for mechanization and automation of the whole quantitative analysis.

In this paper, the carrier arrangement in three-dimensional (3D) circular braiding is studied. To obtain suitable arrangements, the guide grooves of carriers are defined and divided into several types. Restricted conditions of the carrier positions are derived by obeying the characteristics of the carrier motion. Based on the restricted conditions, a mathematical model is established and applied to determine the possible carrier positions. Using the model, reasonable carrier arrangements are discussed. In comparison with practical engineering, the model is proven to be a useful tool for the 3D circular braiding process and helpful for designing a 3D circular braiding machine.

Entanglement distillation is a basic task in quantum information, and the distillable entanglement of three bipartite reduced density matrices from a tripartite pure state has been studied in [Phys. Rev. A 84, 012325 (2011)]. We extend this result to tripartite mixed states by studying a conjectured matrix inequality, namely $\mathop{\rm rank}(\sum_i R_i \otimes S_i)\leq K \mathop{\rm rank}(\sum_i R_i^T \otimes S_i)$ holds for any bipartite matrix $M=\sum_i R_i \otimes S_i$ and Schmidt rank $K$. We prove that the conjecture holds for $M$ with $K=3$ and some special $M$ with arbitrary $K$.

Aiming at the problems of complex trajectory, low efficiency and high operational difficulty of the robot in multi-point punching of warp-knitted vamp, a method of optimizing punching trajectory based on improved ant colony optimization algorithm and Radau pseudospectral method is proposed. After obtaining the position coordinates of punching points, an improved ant colony optimization algorithm is used to calculate the punching sequence of the shortest path through all punching points, and then Radau pseudospectral method is used to solve the optimal trajectory of the laser punching robot. Improved ant colony optimization algorithm combines a distributed calculation method and the positive feedback mechanism. Radau pseudospectral method can transform the optimal control problems into nonlinear programming problems, and the combination of the two can quickly and reliably obtain the optimal solution. To verify the method, under the condition of selecting the same number and location of punching points, the experiments of Radau pseudospectral method to solve the trajectory planning of laser punching robot is carried out. The experimental results show that improved ant colony optimization algorithm can calculate the path of the vamp punching point in a shorter time and with high accuracy. Radau pseudospectral method can obtain smooth trajectories satisfying various constraints, which can meet the requirements of accuracy and efficiency in practical production.

Owing to the good mechanical properties of braided structures, regular braided ropes are increasingly being used in various fields, including marine exploration, aloft work, recreation activities, and oil prospecting. However, under certain severe conditions, they could break, a situation that is absolutely undesired. Thus, predicting their stress distribution and strain-force characteristics when they are subjected to different tensile loads is a pre-requisite for their application. Therefore, in this study, a mathematical model for ropes with regular braided structures is developed, and based on the model, this study reveals that uneven stress distributions in the different strands of regular braided ropes generate different stress distributions and strain-force characteristics in each of the strands. Additionally, the uneven stress distributions in the different strands also induce mechanical failure more readily. Finally, to ensure the reliability of braided ropes in different applications, different strand parameters are compared.

The quality of composite preform has great influence on its mechanical properties. Aiming at the problems of difficulty in robot teaching and unstable braiding angle in the process of braiding three-dimensional complex component, a control method of robot is proposed. Firstly, the mandrel is discretized to ensure that the axis of each discrete mandrel is perpendicular to the braiding point plane, and the orientation and direction of the tool center are calculated. Then, the take-up speed of the robot is calculated, so that the self-adjustment of the braiding angle can be realized in the braiding process. The experimental results show that the control method can effectively reduce the braiding angle error of variable cross-section mandrel within 2°, and can improve the quality of composite products in actual production.

This paper is aimed at analyzing the dynamic behavior of the gear transmission system in a braiding machine. In order to observe the nonlinear phenomenon and reveal the time-varying gear meshing mechanism, a mathematical model with five degrees-of-freedom gear system under internal and external random disturbance of gear system is established. With this model, bifurcation diagrams, Poincare maps, phase diagrams, power spectrum, time-process diagrams, and Lyapunov exponents are used to identify the chaotic status. Meanwhile, by these analytical methods, spur gear pair with or without random perturbation are compared. The numerical results suggest that the vibration behavior of the model is consistent with that of Clifford system. The chaotic system associated parameters are picked out, which can be helpful to the design and control of braiding machines.

In this paper, the harmonic components of grid-connected current are systemically and quantitatively analyzed, including the high-frequency harmonics caused by the modulation, and the low-frequency harmonics injected by the inherent non-linear characteristics and dead-time effects of switching tubes along with the DC voltage secondary pulsation and the grid disturbance. Furthermore, a combined control scheme of repetitive control and state feedback is brought forward, in which the feedforward decoupling for DC voltage and the feedforward compensation for grid voltage are added. The proposed control strategy can eliminate resonance peak of LCL filter, suppress and compensate the low-frequency harmonics, so that quick response and tracking without static error of the system can be realized. Finally, the rationality of the presented harmonic analysis and the validity of the presented combined control scheme are verified on the 3kW inverter experiment system. DOI : http://dx.doi.org/10.11591/telkomnika.v12i2.3578

Precise pile height is an essential quality measurement for sculptured-style jacquard carpet. Constructing correct the yarn tension model is the key to accurately control carpet pile height during manufacturing carpet. This paper described a standard tufting equipment system with essential components in the yarn path. First, the relationship of pile height and pile tension is formulated. Then, the A. P. Minakov Euler formula is introduced into yarn tension modeling which including the yarn guides, sub-line frame, and puller rollers parts. Finally, this tension model is validated by comparing yarn tension simulation result data and experimental measuring data.

In order to facilitate the adjustment of process parameters for tufting machine, a coordinated control system of tufting carpet machines using AC servo motor to feed yarn and backing cloth has been developed. The system adopt adjusting speed of the servo motors which directly connected with the according axis to fulfill the adjustment of yarn delivery and backing cloth feeding instead of adjustment of conventional mechanical transmission chain. According to the actual requirements of control system, designed and developed the control system software and hardware. The system through the program interface to set and adjust the yarn and backing cloth feeding ratios, and send the parameters through CAN bus down to the two axes motion control board which was designed based on DSP microchip, after set the start signal, the DSP control board can adjust the servo motors' speeds coordinate with the monitored spindle's speed and fulfill the yarn and backing cloth feeding speeds in accordance with the spindle's. Through test in prototype machine, the process parameter of yarn and backing cloth feeding ratio could be changed in a short time.

This paper proposed a simulation for tufted carpet's appearance based on Direct3D. By analyzing the space structure of tufted carpet, using arranged loop pile 3D model on backcloth according to design pattern and process variable to simulate tufted carpet appearance. Use NURBS curve to create loop pile model. The texture mapping technology is adopted to simulate the appearance of yarn. Light model is setup for tufted carpet simulation in Direct3D. Using methods similar to physical simulation to simulate loop pile deformation caused by extrusion, and achieve more satisfactory results. Contrasting to planar simulation of tufted carpet, the 3D simulation could reflect the pattern by showing the height difference between loop piles. By changing the camera, the new simulation image can be created from different viewport. The test show the three-dimensional simulation of multi-level tufted carpet based on Direct3D is both feasible and effective.

To help design complex pattern for multi-pile tufted carpet, this paper conducts the study on application development to simulate the appearance of tufted carpet in three-dimension (3D). First set up the 3D geometrical model of loop pile with NURBS curves in 3ds Max. By comparing the models with different loop pile’s cross section and trajectory, an appropriate model was proposed. Process variables also have a great impact on the result of the simulation. The application was developed with Visual C++ and Direct3D. The simulation allows to visualize the tufted carpet in 3D from any point of view. Dislocation and deformation between loop piles have also been achieved. The results indicate the spatial structure of the loop pile has a great influence on the tufted carpets’ appearance, and plays a more important role in appearance simulation.