Effect of residual stress on ACFM crack measurements in drill collar threaded connections

The drill collar threaded connection of the type used in hydrocarbon exploration is a critical component of the drillstring that is highly susceptible to fatigue damage. In an attempt to reduce costly downhole failures the connections are cold rolled to introduce compressive residual stress, and when in service the connections are routinely inspected. The Alternating Current Field Measurement (ACFM) technique is an increasingly popular method of thread inspection, however, results have indicated that the ACFM defect sizing capability may be compromised when it is used to inspect recently cold rolled connections. If a connection is cold rolled without first being defect free, subsequent inspections may under estimate crack depth with the standard interpretation. Inspection before rolling is therefore necessary.     

Multi-fault diagnosis of rolling bearing elements using wavelet analysis and hidden Markov model based fault recognition

Due to the importance of rolling bearings as the most widely used machine elements, it is necessary to establish a suitable condition monitoring procedure to prevent malfunctions and breakages during operation. This paper presents a new method for detecting localized bearing defects based on wavelet transform. Bearing race faults have been detected by using discrete wavelet transform (DWT). Vibration signals from ball bearings having single and multiple point defects on inner race, outer race, ball fault and combination of these faults have been considered for analysis. Wavelet transform provides a variable resolution time–frequency distribution from which periodic structural ringing due to repetitive force impulses, generated upon the passing of each rolling element over the defect, are detected. It is found that the impulses appear periodically with a time period corresponding to characteristic defect frequencies. In this study, the diagnoses of ball bearing race faults have been investigated using wavelet transform. These results are compared with feature extraction data and results from spectrum analysis. It has been clearly shown that DWT can be used as an effective tool for detecting single and multiple faults in ball bearings. This paper also presents a new method of pattern recognition for bearing fault monitoring using hidden Markov Models (HMMs). Experimental results show that successful bearing fault detection rates as high as 99% can be achieved by this approach.     

旋转固井用高抗扭气密封套管的研制与应用

介绍了一种旋转固井用特殊螺纹接头(WSP-NF)高抗扭气密封套管的基本结构和设计思想,运用有限元方法,重点论述了该套管接头抗扭设计及密封设计的方法和准则,并通过全尺寸试验进行了验证。计算和试验结果表明:WSP-NF接头具有先进的扭矩台肩和合理的金属/金属密封结构,有效地克服了API螺纹和传统特殊螺纹接头的不足,具有优良的抗扭性能,气密封能力达到了管体内壁屈服压力。该研究结果可以为开发更多适合油气田实际的特殊螺纹接头套管提供参考。     

弯曲载荷下特殊螺纹接头密封性能的有限元分析

借助Abaqus软件建立了特殊螺纹接头弯曲性能分析有限元模型,并对某个规格特殊螺纹接头进行了纯弯曲的有限元分析。结果表明:随着弯矩的增加,拉伸面接触应力下降,接触长度减小,密封性能下降;而压缩面接触应力上升,接触长度增加,密封性能提高。这些结果说明提高特殊螺纹接头的弯曲性能需要同时提高接头的拉伸与压缩性能。     

A Connectionist Model of Motion and Government in Chomsky's Government-binding Theory

In this paper we present a connectionist model of movement in government-binding (GB) theory. The model is a collection of regularly connected groups of connectionist units using only two architectures: a two-dimensional map, used to model tree structures, and a one-dimensional row used to model constituent feature assignment. GB theory is a constraint-based theory of syntax. The constraints of GB are modeled by the maps, the rows and the connections between them. All the connections are regular—they depend only on the maps being linked, not on the individual units. The model performs the movements in the transition from d-structure to s-structure mandated by the constraints on sentence form.     

Tool design for inner race cold forging with skew-type cross ball grooves

The inner race of CV (Constant Velocity) joints with asymmetric six cross ball grooves is an important load-supporting automobile part that transmits torque between the transmission and a driven wheel. This metal component has conventionally been produced by a machining sequence that includes material removal. As an alternative, a cold forging procedure using a semi-closed die is presented. The proposed cold forging is composed of six longitudinally segmentalized cross-ball grooving dies, a die holder, and forging punches, which were chosen with consideration of their operation mechanisms. Process design and detailed tool design have been conducted. To ensure the appropriateness of the suggested process with respect to deformation behavior, a 3-dimensional finite element simulation including forging load prediction is carried out, and experimental investigations are also performed using SCr420H steel as the initial billet material. Unexpected fracture failure of the die occurred due to the asymmetric geometry of the segmentalized cross ball grooving die, in response to which modification of the die geometry was carried out based on the results from the structural integrity evaluation, thereafter, the inner race was appropriately produced using the modified die. The dimensional accuracy at three critical cross sections of the forged inner race is investigated and compared. It is shown that the proposed semi-closed die cold forging could be successfully applied to the production of the inner race with the six skew-type cross ball grooves, and achieved with the dimensional variation under about 2.0%.     

Analysis of the ironing of a BJ-type constant velocity joint outer race with the upper bound element method

A constant velocity joint outer race is an important load-supporting part in cars, which transmits torque between the transmission gear box and the driving wheel. The outer race is difficult to be forged because its shape is very complicated and its required precision is high. There is no mature technology, especially no cold and warm forging process, to produce this component in China. In order to meet the demands of Chinese automobile industry, the Science Committee of China approved a project named “Development of Constant Velocity Joint Outer Race with Cold and Warm Forging Technology” in 1995. It is one of the key projects in the ninth five-period of China, and is in the charge of Beijing Mechanical and Electrical Research Institute.The key of forging the outer race is how to implement its ironing. This paper analyzes the cold and warm forming of the ironing process of the outer race, in order to offer a theoretical basis for die designing and the choice of press, with the upper bound method. The paper deduces the general equations for computing the forming force and punch pressure for the problem of the ironing of the outer race. In order to testify these equations, this paper computes the numerical solution of the ironing force of the outer race of a Santana car.     

Korrosionsbeständigkeit von Verbindungen von Rohren aus nichtrostenden Stählen in Wässern

Corrosion of joints for stainless steel tubes in water The most important commonly used joining techniques for stainless steel tubes which are used for the transport of water and gases are welding and brazing. With corrosion attack by dry gases, both connections are resistant against corrosion. However, in water and aqueous condensates limits of application exist with regard to the corrosion resistance. The corrosion resistance of weld connections with stainless steel tubes is diminished by

• – annealing colours (oxide films) and scale layers in the weld area;
• – changes in the microstructure adjacent to the welds (sensitization of the stainless steel material);
• – surface finish of weld seams after welding;
• – welding faults resulting from bad handling and workmanship.

Type and extent of corrosion damage occurring on weld connections with decreased corrosion resistance depend on the composition of the water and condensates, mainly on their chloride content. Typical examples for the causes of degraded corrosion resistance of weld connections, and possible types of corrosion attack, namely pitting, crevice corrosion, and stress corrosion cracking and their mechanisms are described. Furthermore, measures are shown by which the corrosion resistance of weld connections with stainless steel tubes can be increased. Joints of stainless steel tubes by hard soldering with capillary fittings are endangered by knife line attack at the phase boundary between the stainless steel and solder (interfacial corrosion). Knife line attack means in this context the loss of adhesion between steel and hard solder. The severity of the corrosion risk, in particular the incubation time until the occurrence of the corrosion damage, depends on the water quality, mainly on chloride concentration, and pH. The press fitting with non-metallic gasket is a relatively new joining system, and it is used in the cold and warm water domestic installation. This joining technique is described. For domestic water distribution, an installation system with tubes and press fittings made of steel grade AISI 316 SS has been developed. This system is resistant to corrosion attack in potable water of usual composition, and it is already applied in-service in a considerable extent. Other joining systems are stainless steel weld fittings, threaded screw fittings, and compression couplings with cutting or clamping rings. They are used mainly in industrial installations.     

基于扁平衰减三角形结构元素的滚动轴承故障诊断

形态滤波性能主要取决于结构元素，目前应用中以直线形结构元素为主，其外形与实际轴承故障时的脉冲信号相似度较弱，影响了冲击特征提取。针对该问题，提出了一种扁平衰减三角形结构元素，并应用滚动轴承故障诊断。通过滚动轴承内外圈故障的振动信号分析，结果表明所建议结构元素能够提取冲击脉冲信号。同时，对比传统扁平直线结构元素应用于相同的振动信号，扁平衰减三角形结构元素能够提高脉冲提取效果。     

基于PLC的管材称重、测长、喷标系统的设计

设计在一个工位上实现钢管称重、测长和喷标的自动化系统.该系统整个工作过程由PLC控制实现全自动,并设计了手动装置,以防在全自动时出现事故.利用组态王开发界面,并实现与PLC、称重仪表的连接.由于称重和测长同时进行,因此节约很多时间.实验结果表明:该系统性能稳定、功能完善、操作简单,每分钟能够完成两根钢管的测量,生产效率高.     

Simulating the ‘Other-race Effect’ as a Problem in Perceptual Learning

We report a series of simulations on the well-known ‘other-race effect’. We trained an autoassociative network on a majority and a minority race of faces, and tested the model's ability to process faces from the two races in different ways. First, the model was better able to reconstruct unlearned majority faces than minority faces. Secondly, the average inter-face similarity was higher for the reconstructed minority faces than for reconstructed majority faces, indicating that the model was coding the majority faces more distinctively than the minority faces. These results held for Caucasian faces as the majority race and Japanese faces as the minority race and vice versa. Thirdly, we simulated a recognition task for same- and other-race faces by using a face history matrix and a recognition task matrix with equal numbers of Caucasian and Japanese faces, and reconstructing these faces as a weighted combination of the two matrices. Using Caucasian faces as the majority race, the model was better able to discriminate learned from new Caucasian faces than learned from new Japanese faces. We discuss the results in terms of perceptual tuning to information useful for processing faces of a single race.     

限制淬透性轴承钢的整体感应加热—表面淬火技术

论述了限制淬透性轴承钢制造的铁路轴承内套圈采用整体感应加热-表面淬火处理的工艺要点及处理工艺与组织性能的关系。该工艺处理的套圈获得表层为马氏体,心部为珠光体的优良强韧性组织和表层大于3mm的压应力层,套圈的疲劳寿命得到有效提高。     

Information Content in Neural Net Optimization

Reduction in the size and complexity of neural networks is essential to improve generalization, reduce training error and improve network speed. Most of the known optimization methods heavily rely on weight-sharing concepts for pattern separation and recognition. In weight-sharing methods the redundant weights from specific areas of input layer are pruned and the value of weights and their information content play a very minimal role in the pruning process. The method presented here focuses on network topology and information content for optimization. We have studied the change in the network topology and its effects on information content dynamically during the optimization of the network. The primary optimization uses scaled conjugate gradient and the secondary method of optimization is a Boltzmann method. The conjugate gradient optimization serves as a connection creation operator and the Boltzmann method serves as a competitive connection annihilation operator. By combining these two methods, it is possible to generate small networks which have similar testing and training accuracy, i.e. good generalization, from small training sets. In this paper, we have also focused on network topology. Topological separation is achieved by changing the number of connections in the network. This method should be used when the size of the network is large enough to tackle real-life problems such as fingerprint classification. Our findings indicate that for large networks, topological separation yields a smaller network size, which is more suitable for VLSI implementation. Topological separation is based on the error surface and information content of the network. As such it is an economical way of reducing size, leading to overall optimization. The differential pruning of the connections is based on the weight content rather than the number of connections. The training error may vary with the topological dynamics but the correlation between the error surface and recognition rate decreases to a minimum. Topological separation reduces the size of the network by changing its architecture without degrading its performance,     

轴承外圈工序间检测的数据采集系统研究

针对目前国内轴承厂家对轴承外圈的几何参数仍然采用人工检测，效率低、劳动强度大、容易引入人为误差、影响产品质量等问题，研制了一种用于轴承外圈几何参数的自动检测系统。该系统利用电感式位移传感器对轴承外圈几何参数进行在线测量，检测效率高，人为因素引起的误差小。     

Evolution and Development of Modular Control Architectures for 1D Locomotion in Six-legged Animats

An evolutionary approach is used to design neural control architectures for virtual sixlegged animats. Using a geometry-oriented variation of the cellular encoding scheme and syntactic constraints that reduce the size of the genetic search space, the developmental programs of straight locomotion controllers are first evolved. One such controller is then included as the first module in a larger architecture, in which a second neural module is evolved and develops connections to the first one, so as to set locomotion on or offaccording to sustained or instantaneous external control signals. Such an incremental approach should prove useful to the automatic design of relatively complex control architectures that might, in particular, implement some cognitive abilities over and above mere stimulus-response mechanisms.     

Teacher-directed learning: information-theoretic competitive learning in supervised multi-layered networks

In this paper, we propose a new type of efficient learning method called teacher-directed learning. The method can accept training patterns and correlated teachers, and we need not back-propagate errors between targets and outputs into networks. Information flows always from an input layer to an output layer. In addition, connections to be updated are those from an input layer to the first competitive layer. All other connections can take fixed values. Learning is realized as a competitive process by maximizing information on training patterns and correlated teachers. Because information is maximized, information is compressed into networks in simple ways, which enables us to discover salient features in input patterns. We applied this method to the vertical and horizontal lines detection problem, the analysis of US–Japan trade relations and a fairly complex syntactic analysis system. Experimental results confirmed that teacher information in an input layer forces networks to produce correct answers. In addition, because of maximized information in competitive units, easily interpretable internal representations can be obtained.     

BJ型等速万向节外套温锻工序的要点

等速万向节外套是轿车重要传动部件，是国家“九五”期间重点支持开发的轿车关键零件之一等速万向节外套属高难成形锻件，由于其材料为ｃｆ５３，采用温－冷锻复合工艺可很好地成形。虽然其温锻工序属一般成形问题，但是仍有一些要点需要注意。用有限元方法分析了温锻过程中出现的问题，并给出解决办法。     

New cross-rolling process for joining of hybrid components

The proposed innovative cross-rolling process can be used to form hybrid components like shaft hub connections and electric drive parts. The advantages as well as the challenges are discussed in detail, especially the resulting notch geometry and possible approaches for mitigating adverse effects. While the shaft ideally should be a high strength steel, generally any other metal, ceramic or composite material can be used as a joining partner. This paper will present a numerical analysis of the joining process regarding work roll path and geometry as well as an experimental evaluation of the achievable properties and the resulting transmissible loads.     

Robust manifold learning with CycleCut

Many manifold learning algorithms utilise graphs of local neighbourhoods to estimate manifold topology. When neighbourhood connections short-circuit between geodesically distant regions of the manifold, poor results are obtained due to the compromises that the manifold learner must make to satisfy the erroneous criteria. Also, existing manifold learning algorithms have difficulty in unfolding manifolds with toroidal intrinsic variables without introducing significant distortions to local neighbourhoods. An algorithm called CycleCut is presented, which prepares data for manifold learning by removing short-circuit connections and by severing toroidal connections in a manifold.     

Tube branching by asymmetric compression beading

This paper draws on the capability of producing out-of-plane instability waves in thin-walled tubes subjected to axial loading. In terms of deformation mechanics, the aim is to identify the operative parameters, to diagnose possible sources of failure and to understand the route for selecting the most appropriate operative conditions for obtaining sound asymmetric compression beads created by out-of-plane instability waves.In terms of industrial technology, the goal is to apply the fundamentals of asymmetric compression beading for developing an innovative tube branching process to join tubes that is capable of eliminating welding and brazing in standard or user made types of connections.The presentation includes details on tool design, independent determination of the mechanical properties of the tubes, finite element modelling and experimentation under laboratory conditions. Results and observations show that tube branching by means of asymmetric compression beading is a flexible and cost-effective technology for joining tubes in standard tee connections as well as in special purpose applications involving custom sizes and dissimilar materials.