Key Engineering Materials Vols. 474-476

Abstract: This paper proposes a new structure of hybrid cam-linkage mechanical press. First of all, the design process is introduced and positive movement simulation is done separately for hybrid cam-linkage mechanism and hybrid seven-bar mechanism in Pro/Mechanism. Through comparing the curves of slider’s output displacement, velocity and acceleration, it comes to the conclusion that the slider of hybrid cam-linkage mechanical press has better output motion characteristics. Then power and torque distribution of servo motor and general motor of the hybrid cam-linkage mechanical press is studied in ADAMS based on the simulation results. At last, torque of general motor and servo motor in practical work is analyzed by taking cold extrusion press as an example.

Abstract: This paper deals with the effects of bending and boundary condition on the stress distribution of a single-lap adhesive joint under tension using the three-dimensional finite element analysis technique. The numerical results obtained from the finite element analysis show that both the left and right hand regions of the adhesive layer are subjected to high stresses. The numerical results also show that most of the extreme stresses occur at interface which is between the adhesive and the upper adherend. It is clear that the stresses are concentrated near the left and right free ends of the adhesive layer while the centre region of the adhesive layer is mostly stress-free. It is also clear that the stress state in this case is mainly dominated by the normal stress components.

Abstract: The two-phase flow is addressed for the more accurate estimation of the wake characteristic for the horizontal-axis wind turbine operating in the complexly unsteady environmental states. The computational fluid dynamics (CFD) method is implemented for performing the three-dimensional wind turbine using the simulating software tool of FLUNT. Three types of environmental states, single-phase flow, liquid-gas flow and solid-gas flow, are performed for the comparison of velocity and pressure distribution to derive the specify feature for wind turbine within two-phase flow environmental state. The calculated results shows that there has the similar evolutional tendency of velocity distribution for both single- and two-phase flows and the velocity decrement at the distance of 20 meter away from wind turbine still reach to 80% of inflow speed. But the turbine blade within two-phase flow is subject to the unsteady flow with the larger velocity gradient compared with that within single-phase flow. For the static pressure, large difference occurred in these three types of environmental state reveals that the second material in addition to atmospheres causes the prominent influence of aerodynamic force and its power coefficient. The results exhibit that wind turbine within solid-gas flow has the largest power coefficient that those within the gas and liquid-gas flows.

Abstract: This paper took Support Object System as the research object. With defining the basic concepts just like combat unit, it constructed the three-dimension researching framework of RM modeling for support object system using System Engineering theory, from parameter, time domain and hierarchical these three aspects. It established the RM parameter system for the smallest combat unit -Basic Equipment Combat Unit’s support object system, with distinguishing the comprehensive and monomial parameters. Operational mission-oriented RM model of baisc equipment combat unit was established subsequently, with multiple modeling theories and methods, such as phased-mission system and reliability block diagram, etc. This model could provide the foundation for operational mission-oriented support resource deployment and support efficiency evaluation.

Abstract: Firewall is the most prevalent and important technique to enforce the security inside the networks. However, effective and free anomalies rules management in large and fast growing networks becomes increasingly challenging. In this paper, we use a directed tree-based method to detect rule anomalies in firewall; in addition, this method can track the source of the anomalies. We believe the posed information will simplify the rules management and minimizing the networking vulnerability due to firewall rules misconfigurations.

Abstract: In order to reduce the average path length of the wireless sensor networks (WSNs) and save the energy, in this paper, the concept of the small world is introduced into the routing designs of WSNs. So a new small world routing protocol (SWRP) is proposed. By adding a few short cut links, which are confined to a fraction of the network diameter, we construct a small world network. Then the protocol finds paths through recurrent propagations of weak and strong links. The simulation results indicate that SWRP reduces the energy consumption effectively and the average delay of the data transmission, which leads to prolong the lifetime of both the nodes and the network.

Abstract: The purpose of reverse engineering is to convert a large points cloud into a CAD model. Parameters extraction for extruded surface from measure data is an important problerm in reverse engineering. Extruded direction is a crucial parameter of extruded surface. In this paper, random sampling consensus algorithm combined with Least-Squares method is used to extract the extruded direction of extruded surface. Experimental results show effectiveness, robustness and accuracy of this proposed approach.

Abstract: Based on the screw theory,the paper presents a systematic method for structural synthesis of the two rotations and one translation parallel robot.According to the reciprocal product between kinetic screw and constrainted screw in screw theory.This method firstly creats possible branch structures and then generates diferent models of mechanism.By this method,the paper carries on the structural synthesis of the two rotations and one translation parallel robot,and also lists some of the mechanisms including a few new ones. Analyzsis solution of direct and inverse position.The dynamic simulation was conducted using the software of Adams.

Abstract: The paper proposes a digital image extraction and segmentation algorithm based on color features. The traditional transformation from RGB model to HSI model is improved, meanwhile the leaf color information is extracted by similarity distance between pixels. The green component of leaf image in the RGB model is strengthened, and then the digital image is transformed to the HSI model by the improved method. Finally the image is divided by similarity distance of pixels’ H weight which determines whether the pixel belongs to the blade. The results of simulation experiment shows that this algorithm can achieve a good image segmentation effect, and it has a high degree of accuracy as well as a clearly distinguish degree and many other advantages such as good consistency with human visual system. It completely meets the effectiveness and clarity requirements of image segmentation.

Abstract: A combined coordinate measuring mechanical arm (CCMMA) was developed to test the operational ability of astronaut in the EVA spacesuit. The equipment measures the space region coordinates of the astronaut’s hand-reach while forces act on a handle. The homogeneous transformation equations of CCMMA are established based on Modified Denavit-Hartenberg (MDH). Measurement error was analyzed and distance error model of CCMMA was set up to improve measurement precision. The improved genetic algorithm is applied to the identification of CCMMA structure parameters. The calibration experiment of CCMMA was carried out using such model and algorithm. The result showed that with identification, the repeatability and length measurement precision were improved by 5.38 and 3.11 times respectively.