A method of constructing an inspiration library driven by user-perceived preference evaluation data for biologically inspired design

Biologically inspired design (BID) is one of the common methods for product design. To solve the problem of inaccurate acquisition of inspirational creatures due to the lack of user perception preference analysis, a data-driven intelligent service model for BID considering user perception needs is proposed based on Kansei engineering. Firstly, by extracting the perceptual features of creatures from the semantic source elements of products through mapping and encodes them, we proposed a data acquisition method based on intuitionistic fuzzy sets considering different customer preference distributions, bridging the gap caused by the asymmetry between designers and users. Secondly, the functional relationship between biometric features and user-perceived attributes is identified and predicted, and a predictive model of biodata considering user preferences is obtained by multiple linear regression analysis. Finally, based on the data clustering and reorganization theory to understand the organization and dynamics of the database, the construction of a BID library was completed, and the design resources in the library were used as analyzed knowledge for designers to plan design activities. Taking the bionic design of a UAV product as an example, a prototype of a computer-aided design service system was developed based on the theory proposed in the article, and the analyzed knowledge was used to improve the efficiency and science of the design, effectively verifying the usefulness of this study for design. To a certain extent, this study addresses the problem of cognitive limitations of designers and cognitive differences between designers and users, promotes the application of bioinspiration in product design, and improves the marketability of design solutions.     

Development of a small DMFC bipolar plate stack for portable applications

The direct methanol fuel cell (DMFC) is regarded as a promising candidate in portable electronic power applications. Bipolar plate stacks were systematically studied by controlling the operating conditions, and by adjusting the stack structure design parameters, to develop more commercial DMFCs. The findings indicate that the peak power of the stack is influenced more strongly by the flow rate of air than by that of the methanol solution. Notably, the stack performance remains constant even as the channel depth is decreased from 1.0 to 0.6 mm, without loss of the performance in each cell. Furthermore, the specific power density of the stack was increased greatly from ∼60 to ∼100 W l⁻¹ for stacks of 10 and 18 cells, respectively. The current status of the work indicates that the power output of an 18-cell short stack reaches 33 W in air at 70 °C. The outer dimensions of this 18-cell short stack are only 80 mm × 80 mm × 51 mm, which are suitable for practical applications in 10–20 W DMFC portable systems.     

Flame inertia into lean region in stratified hydrogen mixture

In hydrogen engines, the direct-injection stratified charge system has the ability to realize a more lean operation than homogeneous charge systems. Flame propagation into the lean region in the stratified hydrogen mixture was investigated in this study. Hydrogen was injected into a lean hydrogen–air premixed mixture charge of the equivalence ratio of 0.074–0.257. This stratified hydrogen mixture was ignited by an electric spark. The flame generated in the hydrogen jet propagated into the lean premixed mixture charge as if it had “inertia”, even though the stoichiometry of the premixed mixture charge was less than the lower flammability limit. The amount of burned hydrogen in the case of a stratified mixture was greater than that in the case of the homogeneous mixture. The flame seems to be supported from behind by the burned gas in the rich region until the decay of this support.     

Hybrid active/passive force control strategy for grinding marks suppression and profile accuracy enhancement in robotic belt grinding of turbine blade

Grinding marks and traces, as well as the over- and under-cutting phenomenon are the severe challenges in robotic abrasive belt grinding of turbine blades and it greatly limits the further application of robotic machining technology in the thin-walled blade fields. In the paper, an active force control method consisting of force/positon and PI/PD controller based on six-dimensional force/torque sensor is introduced to eliminate the grinding marks and traces, and a passive force control method including PID controller based on one-dimensional force sensor is proposed to reduce the over- and under-cutting phenomenon in robotic machining system. Then the Kalman filter information fusion methodology is adopted to combine the active and passive force control methods which could improve the controlled force accuracy and efficiency, as well as avoid the control interference. Finally both the test workpiece and turbine blade are employed to examine and verify the reliability and practicality of the proposed hybrid force control method by achieving the desired surface quality and higher profile precision.     

Online stiffness estimation for robotic tasks with force observers

In this paper we propose an online stiffness estimation technique for robotic tasks based only on force data, therefore, not requiring contact position information. This allows estimations to be obtained in robotic tasks involving interactions with unstructured and unknown environments where geometrical data is unavailable or unreliable. Our technique – the Candidate Observer Based Algorithm (COBA) – uses two force observers, configured with different candidate stiffnesses, to estimate online the actual target object stiffness. COBA is embedded in a force control architecture with computed torque in the task space. The theoretical presentation of the algorithm, as well as simulation tests and experimental results with a lightweight robot arm are also presented.     

A new force-depth model for robotic abrasive belt grinding and confirmation by grinding of the Inconel 718 alloy

Robotic abrasive belt grinding has been successfully applied to the grinding and polishing of aerospace parts. However, due to the flexible characteristics of robotic abrasive belt grinding and the time-varying characteristics of the polishing contact force, as well as the plastic and difficult-to-machine material properties of Inconel 718 alloy, it is very difficult to control the actual removal depth and force of the polished surface, which brings great challenges to robot automatic polishing. Therefore, the relationship between the grinding force and the grinding depth in the robotic abrasive belt grinding is analyzed in detail, the robot machining pose error model considering the deformation of the grinding head is established, and the Inconel 718 alloy machining experiment of the robotic abrasive belt grinding is designed. The mapping relationship between the grinding force and the grinding depth is obtained, and the grinding force ratio in the downgrinding and upgrinding mode is discussed. The experimental and theoretical comparisons results show that with the increase of the grinding depress depth, both the grinding depth and the grinding force show an irregular increasing trend, and the increasing trend of the grinding force (increases by about 344.44%–445.45%) is obviously greater than that of the grinding depth (increases by about 52.94%). When the grinding depress depth is large (greater than 3 mm), the feed direction force and the normal force appear obvious secondary pressure peaks at the beginning and end of grinding, which has not been seen in previous studies. In addition, regardless of whether it is downgrinding or upgrinding, the grinding force ratio decreases with the increase of the depress depth, and the grinding force ratio of downgrinding (average 0.668) is smaller than that of upgrinding (average 0.724). This study provides a reference for robotic abrasive belt grinding, and the surface quality of Inconel 718 alloy of robotic abrasive belt grinding can be further improved through the optimization of force and depth.     

Traffic sign detection based on improved faster R-CNN for autonomous driving

The timely and accurate identification of traffic signs plays a significant role in realizing the autonomous driving of vehicles. However, the size of traffic signs accounts for a low proportion of the input picture, which increases the difficulty of detection. This paper proposes an improved faster R-CNN traffic sign detection method. ResNet50-D feature extractor, attention-guided context feature pyramid network (ACFPN), and AutoAugment technology are designed for the faster R-CNN model. ResNet50-D is selected as the backbone network to obtain more characteristic information. ACFPN is performed to decrease the loss of contextual information. And data augmentation and transfer learning are adopted to make model training more convenient and time-saving. To prove the availability of the proposed method, we compare it with mainstream approaches (SSD, YOLOv3, RetinaNet, cascade R-CNN, FCOS, and CornerNet-Squeeze) and state-of-the-art methods. Experimental results on the CCTSDB dataset show that the improved faster R-CNN achieves the frames per second of 29.8 and the mean average precision of 99.5%, which is superior to the state-of-the-art methods and more suitable for traffic sign detection. Moreover, the proposed model is extended to the Tsinghua-Tencent 100 K (TT100K) dataset and also achieves a competitive detection result.

     

基于网络资源流量的链路预测方法

在复杂网络中,现有基于结构相似性的链路预测方法较少考虑全局和局部拓扑信息之间平衡性、准确度和复杂度之间平衡性以及网络资源动态流动的问题。将网络资源流量作为相似性判断依据,提出一种准局部链路预测方法。根据网络中节点重要性的不同来为它们分配对应的资源,以保证资源分配的合理性。针对网络资源提出一种动态流动机制,将节点对双向流动的资源之和作为相似程度的量化指标。引入节点对之间中间路径节点的概念,分析中间路径节点在资源流动过程中的稀释作用。在此基础上,计算初始资源量和稀释作用量从而得到网络资源流量方法的性能评估指标值。在Jazz、NS等11个真实世界的网络中进行实验,对比该方法与CN、Salton等常见基准方法在准确度和鲁棒性方面的性能表现,结果表明,所提方法能够充分利用准局部信息,既能考虑资源流动性又能解决平衡性问题,可有效提高链路预测性能。     

Cooperation and profit allocation in two-echelon logistics joint distribution network optimization

Collaborative two-echelon logistics joint distribution network can be organized through a negotiation process via logistics service providers or participants existing in the logistics system, which can effectively reduce the crisscross transportation phenomenon and improve the efficiency of the urban freight transportation system. This study establishes a linear optimization model to minimize the total cost of two-echelon logistics joint distribution network. An improved ant colony optimization algorithm integrated with genetic algorithm is presented to serve customer clustering units and resolve the model formulation by assigning logistics facilities. A two-dimensional colony encoding method is adopted to generate the initial ant colonies. Improved ant colony optimization combines the merits of ant colony optimization algorithm and genetic algorithm with both global and local search capabilities. Finally, an improved Shapley value model based on cooperative game theory and a cooperative mechanism strategy are presented to obtain the optimal profit allocation scheme and sequential coalitions respectively in two-echelon logistics joint distribution network. An empirical study in Guiyang City, China, reveals that the improved ant colony optimization algorithm is superior to the other three methods in terms of the total cost. The improved Shapley value model and monotonic path selection strategy are applied to calculate the best sequential coalition selection strategy. The proposed cooperation and profit allocation approaches provide an effective paradigm for logistics companies to share benefit, achieve win–win situations through the horizontal cooperation, and improve the negotiation power for logistics network optimization.     

The influence of corrosion on the life of steel ropes and prediction of their decommissioning

Operation of steel wire ropes brings a number of risks that affect their lifetime. During operation of steel ropes the one of the most adverse effects is the effect of corrosion. Manufacturers are working hard to eliminate the effect of corrosion by lubricating cables, surface protection of wires and alike, but these methods are not able eliminate corrosion rise and propagation totally. To examine the process of degradation of the mechanical properties of the steel ropes in the corrosive environment, we conducted research on a rope sample as a whole and on the samples of individual wires. The samples were exposed to the saline solution for a period of total duration of 64 days. The monitoring of the degradation was carried out at 16-day intervals when the samples were subjected to mechanical tests. The rope sample as a whole was subjected to the tensile test. The individual wire samples were subjected to the tensile test, alternating bend test and torsion test. The criteria according to the standard EN 12927-6 and the Slovak Mining Office Regulation (SBU) No. 50/1989 Coll. were used to evaluate the results of the degradation of the mechanical properties. These were then confronted with the criteria used in maritime shipping. Based on the results of the mechanical tests, the trend of the degradation of the mechanical properties in the saline solution and marginal values for the rope decommissioning were determined. Gradually, with an increase of the impact of corrosion on the rope samples, the impact on rope rotation resistivity was also registered, besides the mechanical properties changes.