电刷镀技术在修复ND_2型机车柴油机下机体上的应用和探讨

按传统工艺 ,柴油机下机体的电刷镀层厚度很难超过 0 5mm ,本文对应用电刷镀技术修复ND2 型机车柴油机下机体时如何突破 0 5mm镀层进行分析计算及探讨。

9F-45型锤片式饲料粉碎机的合理使用

一、操作1.开机前,必须认真检查各部件螺栓是否拧紧,尤其是锤销轴及刀片固定螺母和上下机体的紧固手柄要拧紧,皮带的松紧度应适宜。2.对粉碎的物料要进行清选,严防有金属或者石块等硬物,以免损坏机器或发生事故。物料的含水率要在15%以下。3.检查主轴是否转动灵活,有没有卡碰或者摩擦声音。

Using CFD Software to Calculate Hydrodynamic Coefficients

Applications of computational fluid dynamic(CFD) to the maritime industry continue to grow with the increasing development of computers.Numerical approaches have evolved to a level of accuracy which allows them to be applied for hydrodynamic computations in industry areas.Hydrodynamic tests,especially planar-motion-mechanism(PMM) tests are simulated by CFD software-FLUENT,and all of the corresponding hydrodynamic coefficients are obtained,which satisfy the need of establishing the simulation system to evaluate maneuverability of vehicles during the autonomous underwater vehicle scheme design stage.The established simulation system performed well in tests.

The design of underwater hull-cleaning robot

The research on underwater ship-hull cleaning robot was conducted on the purpose of realizing the automation of cleaning underwater ship hull so that service life of ship will be prolonged and ship speed will raised. Moreover, fuel consumption and the work intensity of divers will be reduced. In this paper, the current situation and the latest technology in China and abroad were analyzed;meanwhile, the typical characteristics of the underwater cleaning robot were introduced. According to the work principle of the underwater cleaning robot, the emphasis was put on the analysis and study of permanent-magnetic absorption, magnetic wheel, airproof and anticorrosion, underwater cleaning equipment and control system. The robot is easy in rotation and simple in control.

A new robust fuzzy method for unmanned flying vehicle control

A new general robust fuzzy approach was presented to control the position and the attitude of unmanned flying vehicles(UFVs). Control of these vehicles was challenging due to their nonlinear underactuated behaviors. The proposed control system combined great advantages of generalized indirect adaptive sliding mode control(IASMC) and fuzzy control for the UFVs. An on-line adaptive tuning algorithm based on Lyapunov function and Barbalat lemma was designed, thus the stability of the system can be guaranteed. The chattering phenomenon in the sliding mode control was reduced and the steady error was also alleviated. The numerical results, for an underactuated quadcopter and a high speed underwater vehicle as case studies, indicate that the presented adaptive design of fuzzy sliding mode controller performs robustly in the presence of sensor noise and external disturbances. In addition, online unknown parameter estimation of the UFVs, such as ground effect and planing force especially in the cases with the Gaussian sensor noise with zero mean and standard deviation of 0.5 m and 0.1 rad and external disturbances with amplitude of 0.1 m/s2 and frequency of 0.2 Hz, is one of the advantages of this method. These estimated parameters are then used in the controller to improve the trajectory tracking performance.

Research on mechanism of mountain landslide due to underground mining

The basics of mining landslides were first summed up based on the analysis ofactual materials by the application of mining subsidence and landslide theories. Further,the mechanism of along-layer landslide by mining was studied with the example of theXiangshan mining landslide at Hancheng, Shaanxi Province. Meanwhile, the state ofstress, and the mechanism of deformation and destruction of the Xiangshan mining slopewere analyzed by the Finite Element Method.

Underwater Image Bidirectional Matching for Localization Based on SIFT

For the purpose of identifying the stern of the SWATH （Small Waterplane Area Twin Hull） availably and perfecting the detection technique of the SWATH ship＇s performance, this paper presents a novel bidirectional image registration strategy and mosaicing technique based on the scale invariant feature transform （SIFT） algorithm. The proposed method can help us observe the stern with a great visual angle for analyzing the performance of the control fins of the SWATH. SIFT is one of the most effective local features of the scale, rotation and illumination invariant. However, there are a few false match rates in this algorithm. In terms of underwater machine vision, only by acquiring an accurate match rate can we find an underwater robot rapidly and identify the location of the object. Therefore, firstly, the selection of the match ratio principle is put forward in this paper; secondly, some advantages of the bidirectional registration algorithm are concluded by analyzing the characteristics of the unidirectional matching method. Finally, an automatic underwater image splicing method is proposed on the basis of fixed dimension, and then the edge of the image＇s overlapping section is merged by the principal components analysis algorithm. The experimental results achieve a better registration and smooth mosaicing effect, demonstrating that the proposed method is effective.

Research of the underground coal bunker clearing robot

With the long-term use of coal bunker, a certain amount of sticking objects will beformed on its wall, and coal mine clearing robot can replace man in clearing the bunker wall.Also, since it equip with an explosion-proof camera, the worker can determine the operationby observing the well-head monitor.Moreover, it cannot work unless it is placed in positionand supported stably, and it has three degrees of freedom: rotating, stretching, and shovelcoal.It is driven by the hydraulic and controlled by PLC.The underground coal mine clearingrobot changs the traditional clearing methods, man does not have to enter the bunker toclear it, which ensures the production safety of coal transportation.

Integrated evaluation system under randomness and fuzziness for groundwater contamination risk assessment in a little town, Central China

An integrated evaluation system under randomness and fuzziness was developed in this work to systematically assess the risk of groundwater contamination in a little town, Central China. In this system, randomness of the parameters and the fuzziness of the risk were considered simultaneously, and the exceeding standard probability of contamination and human health risk due to the contamination were integrated. The contamination risk was defined as a combination of "vulnerability" and "hazard". To calculate the value of "vulnerability", pollutant concentration was simulated by MODFLOW with random input variables and a new modified health risk assessment(MRA) model was established to analyze the level of "hazard". The limit concentration based on environmental-guideline and health risk due to manganese were systematically examined to obtain the general risk levels through a fuzzy rule base. The "vulnerability" and "hazard" were divided into five categories of "high", "medium-high", "medium", "low-medium" and "low", respectively. Then, "vulnerability" and "hazard" were firstly combined by integrated evaluation. Compared with the other two scenarios under deterministic methods, the risk obtained in the proposed system is higher. This research illustrated that ignoring of uncertainties in evaluation process might underestimate the risk level.

Dynamics Modeling and Simulation of Autonomous Underwater Vehicles with Appendages

To provide a simulation system platform for designing and debugging a small autonomous underwater vehicle＇s （AUV） motion controller, a six-degree of freedom （6-DOF） dynamic model for AUV controlled by thruster and fins with appendages is examined. Based on the dynamic model, a simulation system for the AUV＇s motion is established. The different kinds of typical motions are simulated to analyze the motion performance and the maneuverability of the AUV. In order to evaluate the influences of appendages on the motion performance of the AUV, simulations of the AUV with and without appendages are performed and compared. The results demonstrate the AUV has good maneuverability with and without appendages.

Semi-physical simulation of AUV pipeline tracking

Before the task of autonomous underwater vehicle(AUV) was implemented actually,its semi-physical simulation system of pipeline tracking had been designed.This semi-physical simulation system was used to test the software logic,hardware architecture,data interface and reliability of the control system.To implement this system,the whole system plan,including interface computer and the methods of pipeline tracking,was described.Compared to numerical simulation,the semi-physical simulation was used to test the real software and hardware more veritably.In the semi-physical simulation system,tracking experiments of both straight lines and polygonal lines were carried out,considering the influence of ocean current and the situation of buried pipeline.The experimental results indicate that the AUV can do pipeline tracking task,when angles of pipeline are 15°,30°,45° and 60°.In the ocean current of 2 knots,AUV could track buried pipeline.