Optimal Neural Network Model for Characterization of Process-Induced Damage in Drilling Carbon Fiber Reinforced Epoxy Composites

In this paper, a method for robust design of a neural network (NN) model for prediction of delamination (Da), damage width (Dw), and hole surface roughness (Ra) during drilling in carbon fiber reinforced epoxy (BMS 8-256) is presented. This method is based on a parametric analysis of neural network models using a design of experiments approach. The effects of number of neurons (N), hidden layers (L), activation function (AF), and learning algorithm (LA) on the mean square error (MSE) of model prediction are quantified. Using the aforementioned method, a robust NN model was developed that predicted process-induced damage with high accuracy.     

An integrated system for process planning and cost estimation in hole making

The process planning function plays a critical role not only in computer integrated manufacture, but also in the economics of batch manufacturing. This paper describes the development of a generic knowledge-based system for process planning and cost estimation in the hole making process. The main function of the system, besides estimating the cost of production, is to recommend appropriate processes, their sequence and their respective machining conditions in order to obtain the required product specifications. The system has been implemented in a manufacturing organisation. The results obtained have indicated that in addition to cost savings the system also preserves the consistency in planning and cost estimation.     

提高脉冲激光打孔质量的措施

分析JG-2A型脉冲激光器打孔过程中存在的质量问题及其影响因素。同时提出了改善打孔质量的措施：（1）根据最小二乘法原理建立脉冲激光能量经验公式来选取工艺参数；（2）谐振腔超声调制法；（3）材料的热吸收效应法。在实际应用中，打孔质量明显改善。     

基于SolidWorks的相似零件快速创成

介绍了利用Solidworks软件复杂功能，建立系列零件设计表即Excel表，通过其对配置的驱动，自动生成三维相似零件，从而建立相似零件库。该方法简单实用，有效地缩短了设计时间。     

Laser Ablation and Laser-Hybrid Ablation Processes: A Review

Laser beam machining (LBM) has proven its applications and advantages over almost all the range of engineering materials. It offers its competences from macro-machining to micro- and nano-machining of simple-to-complex shapes. The hybrid approaches in laser ablation have demonstrated much improved results in terms of material removal rate, surface integrity, geometrical tolerances, thermal damage, metallurgical alterations, and many more. The flipside of LBM is the existence of universal problems associated with its thermal ablation mechanism. In order to alleviate or reduce the inherent problems of LBM, a massive research has been done during the past decade in order to build a relatively new route of laser-hybrid processes. This paper reviews the research work carried out so far in the area of LBM and its hybrid processes for different materials and shapes. The article also highlights the research gaps and future research directions in the context of laser and laser-hybrid ablation.     

Directional hydraulic fracturing to control hard-roof rockburst in coal mines

Hard roof is the main factor that induces rock-burst.In view of the present obvious weakness of control measures for hard roof rockburst in domestic collieries,the mechanism and field application of di...     

Experimental investigation,prediction and optimization of cylindricity and perpendicularity during drilling of WCB material using grey relational analysis

Manufacturing is always the heart of majority of industries. Drilling is an extremely important and an essential machining process which requires a lot of attention as in most of the cases it is required for assembly purposes. Majority of the holes produced during drilling are made with the help of Vertical Machining Centre (VMC) meant for pin- hole assembly. Though the tolerance is within limit, assembly problems arise due to the improper geometry of these holes. Various geometrical tolerances like cylindricity, circularity, perpendicularity and position errors are responsible for such assembly problems. This investigation is focussed on cylindricity and perpendicularity in the drilling of Wrought Cast Steel Grade B (WCB) material using SOMX 050204 DT insert. In this work, effect of machining variables like cutting speed, feed rate and depth of cut (canned cycle) are investigated and optimized using grey relational analysis (GRA). Reliable experiments are conducted based on a 3³ full factorial, replicated twice. Second order regression models are developed for predicting cylindricity and perpendicularity. The models’ adequacy has been checked by calculating correlation coefficient. It shows that the developed models are well fitted for the prediction of responses within the specific range of input variables.     

Optimized Gabor features for mass classification in mammography

Gabor filter bank has been successfully used for false positive reduction problem and the discrimination of benign and malignant masses in breast cancer detection. However, a generic Gabor filter bank is not adapted to multi-orientation and multi-scale texture micro-patterns present in the regions of interest (ROIs) of mammograms. There are two main optimization concerns: how many filters should be in a Gabor filter band and what should be their parameters. Addressing these issues, this work focuses on finding optimizing Gabor filter banks based on an incremental clustering algorithm and Particle Swarm Optimization (PSO). We employ an SVM with Gaussian kernel as a fitness function for PSO. The effect of optimized Gabor filter bank was evaluated on 1024 ROIs extracted from a Digital Database for Screening Mammography (DDSM) using four performance measures (i.e., accuracy, area under ROC curve, sensitivity and specificity) for the above mentioned mass classification problems. The results show that the proposed method enhances the performance and reduces the computational cost. Moreover, the Wilcoxon signed rank test over the significance level of 0.05 reveals that the performance difference between the optimized Gabor filter bank and non-optimized Gabor filter bank is statistically significant.     

Formation of methane hazard in longwall coal mines with increasingly higher production capacity

Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.     

Tool materials influence on surface roughness and oversize in machining glass fiber reinforced polypropylene (GFR-PP) composites

Glass fiber reinforced Polypropylene (GFR-PP) is used in manufacturing industries like bicycles, auto bodies, aircraft, and civil applications due to superior properties. Machining of fiber-reinforced plastics is problematic especially when drilling due to their inherent in-homogeneity, anisotropy and limited plastic deformation. Drilling is often required to facilitate the assembly of the parts to get the final products. Surface quality in drilled composites is an essential design characteristic in many situations, such as accurate fits, aesthetic requirements, etc. The present work deals with detailed investigation on the influence of tool materials and machining parameters during drilling of GFR-PP composite material. The study mainly focused on machined surface quality such as surface roughness of the drilled hole and dimensional inaccuracies such as oversize of the hole. The better dimensional and surface quality of drilled hole is observed from solid carbide drill with a spindle speed of 2500?rpm and a feed rate of 0.05?mm/rev. Regression model is developed using experimental data for estimating the surface roughness and oversize. The developed model has high R-sq value which shows the strong relationship between the model and the response variables. The effect of drilling process parameters and associated interactions are discussed in detail.