Realization of STEP-NC enabled machining

A STEP-compliant CNC machine tool that demonstrated a G-code free machining scenario is presented. The aim of this research is to showcase the advantages of, and evaluate, STEP-NC—a new NC data model—by implementing it in a legacy CNC system. The work consists of two parts: retrofitting an existing CNC machine and the development of a STEP-compliant NC Converter called STEPcNC. The CompuCam's motion control system is used for retrofitting the machine, which is programmable using its own motion control language—6K Motion Control language and capable of interfacing with other CAPP/CAM programs through languages such as Visual Basic, Visual C++ and Delphi. STEPcNC can understand and process STEP-NC codes, and interface with the CNC controller through a Human Machine Interface. It makes use of STEP-NC information such as “Workplan”, “Workingstep”, machining strategy, machining features and cutting tools that is present in a STEP-NC file. Hence, the system is truly feature-based. The Application Interpreted Model of STEP-NC has been used.     

Security procedures for program libraries

As computer programming has become more complex, management has become more concerned about its own ability to exercise appropriate control over the programmer.This paper describes an implementation of procedures, libraries, and separation of duties to improve security in programming. This implementation helps to limit scope, reveal programmer intent and fix accountability. It assumes and supports such improved programming technologies as top-down design, structured programming, psuedo-code documentation, use of librarians, inspections, and “walk-throughs”.While the implementation described here will contribute to security, it is not sufficient. Management will wish to consider the application of many other measures.     

Making macrospace effective

Macros can provide an important assembly language feature which makes the power of assembly language when multiple levels of nesting are permitted, comparable to that of procedure oriented languages. The problem with macros is that each time one is invoked, it produces a considerable amount of code when anything complicated is done. To retain the power of the macro while at the same time eliminating most of the space consuming property, closed subroutines are nested within the macro. A minimum amount of code is required for the closed subroutine, specifically its calling sequence and housekeeping functions. It is possible to reduce the length of code for the macro which is necessary in the caller's control section by moving the closed subroutine to an entirely different control section. These functions taken together enable the assembly language programmer to keep his modules compact so that a minimum of base register, allocation and manipulation is required.     

Worksheets and Notebooks: Can We Teach Mathematical Algorithms with Them?

This paper describes how computer algebra systems can be used to help students understand mathematical algorithms. Since one can write programs in these systems, one way to help the students is to show them complete programs and try to show them what the programs do. However, programs are like black boxes; you see what goes in and what comes out. To understand the program you need to show the steps that it makes because most students need to see a worked example in detail in order to see what an algorithm is doing before they understand how it works. Another problem with programs is that programs force you to be explicit about details; you must formulate the termination conditions, estimate degree bounds, specify domains of variables, etc. These details often get in the way of illustrating the basic algorithm.The premise of this article is that interactive worksheets and notebooks, which are now available in several computer algebra systems, sometimes provide a better alternative than programs as a teaching aid. In a worksheet or notebook, we can present an algorithm by following the sequence steps done. If part of the algorithm is difficult to express as a single command, or difficult to program, the results can be “typed in” instead. Other parts which may be difficult to formalize in a program, may be very obvious from looking at the output. To illustrate this, we have presented five algorithms as worksheets which we have used for teaching undergraduate mathematics and computer science classes.     

A software authentication system for information integrity

This paper describes a software authentication technique based on the public key cryptography for information integrity. The software provider can use a secret key to sign any released program and the user can verify the integrity of programs obtained from vendors or a “trusted information database”. The software provider needs to go through a registration process to become “licensed” and obtains certificates from multiple certificate centers before being able to sign any released program. Users need only one public key to verify the integrity of the programs.     

“Digi-code” - A micro computer program to digitize two dimensional figures and convert the data to CNC (Computer Numerical Control) Program

Engraving or machining free-form non mathematically defined shapes can be a complex task. “Digi-code” is a program to read and interpret coordinate location data describing parts or shape outlines. The coordinate data is converted directly to NC (Numerical Control) code to control a CNC (Computer Numerical Control) machine tool. This paper describes a technique to digitize contoured shapes and process the data directly to machine control code.     

KBE—Pascal:基于知识的程序编辑

KBE-Pascal是一种交互式的程序设计助手系统,其意图是程序员完成设计和实现的困难部分,由KBE-Pascal尽可能地帮助他。 KBE-Pascal的主要基础是格局,这是一种表示程序的方法,它抽去了程序的非基本特性,且明显地表示出算法的基本逻辑特性。 KBE-Pascal的设计目标是通过引用格局库中的断片,快速正确地构造程序。它的目标语言是Pascal。目前该系统由四部分组成:编码程序,用以产生对应于格局的程序正文;一个通用算法片断格局库;格局编辑程序,使得程序能通过修改格局而达到修改程序的目的;正文     

Fast,accurate call graph profiling

Existing methods for call graph profiling, such as that used by gprof, deal badly with programs that have shared subroutines, mutual recursion, higher‐order functions, or dynamic method binding. This article discusses a way of improving the accuracy of a call graph profile by collecting more information during execution, without significantly increasing the overhead of profiling. The method is based on keeping track of a context, consisting of the set of subroutines that are active at a particular moment during execution, together with the calling arcs between these subroutines. The profiler records the time spent in each context during execution of the program, and thus obtains an accurate measurement of the total time during which each subroutine was active. By recording arc information for only the most recent activation of each subroutine, it is possible to arrange that even recursive programs give rise to a finite number of these contexts, and in typical real programs, the number of distinct contexts remains manageably small. The data can be collected efficiently during execution by constructing a finite‐state machine whose states correspond to contexts, so that when a context is entered for a second or subsequent time, only a single access of a hash table is needed to update the state of the profiling monitor. Copyright © 2003 John Wiley & Sons, Ltd.     

A FORTRAN IV program for the analysis of tectonic strain using deformed elliptical markers

A FORTRAN IV computer program is presented which provides an objective approach to tectonic-strain marker analysis. The algorithms are based on the “Theta-Curve” method and include a test (chi-square, goodness of fit) to check the validity of an initially random marker deformation model. Graphically represented values of confidence versus calculated tectonic-strain estimates, are produced for critical interpretation of results.Orientation data are not dependent on any preconceived reference directions such as cleavage or bedding. The method does assume, in its undeforming procedure, that the median value of the deformed marker-orientations is equivalent to the direction of maximum extension in the finite-strain ellipse.Optional line-printer graphics in separate subroutine form are included for producing the widely accepted diagrams and may be interfaced easily with other strain-analysis programs. A data-conversion program is appended to enable the use of preexisting data sets intended for the STRANE program of Dunnet and Siddans.     

On the analysis and solution of certain geographical optimal covering problems

The article formulates, analyses and suggests solutions to some optimal covering problems that often arise in association with geographical coordinates, albeit their mathematical form may be detached from this background. It shows that under a general formulation no favorable mathematical properties can be deduced beyond the “center of gravity”, and thus that computational algorithms are seemingly the best resort for resolving the problem. An algorithm that is based on the steepest descent approach and that exploits the “center of gravity” property is devised, and is shown as a detector of local minima points. A release from the “locality trap” is provided by a stochastic algorithm.Every part of the paper is accompanied by illustrative examples, either of an analytical nature on a segment of the real line or of a numerical nature by computer programs.     

A FORTRAN decoder and evaluator for use at operation time

Except for normative components, the calculation of which is sufficiently involved to require a separate subroutine, the compositional “derived variables” of chemical petrology may be cast readily in the form of simple arithmetic expressions. With regard to the design of petrographic data bases and their associated information systems, the practical question is whether these should be processed by the base builder, so that the values of each derived variable are incorporated in the base, by an ad hoc subroutine linked to the information system prior to each retrieval or reduction, or by permanent elements of the information system. The third option requires intrinsic capability for decoding and evaluating expressions received as character strings at operation time. Subroutines DKDXPR and EVLXPR provide that capability. Calling program IMDEVL provides a convenient conversational device for testing DKDXPR and EVLXPR.     

Modelling 3D shaded solids of arbitrary shape using an edge-oriented algorithm

A fast hidden-line eliminating algorithm is introduced which enables creation of 3D shaded images. The algorithm also supports set operations on bodies. It deals only with solids bounded by planar patches (curved surfaces are approximated by polyhedra). This makes it possible to implement a simple shading technique. Bodies of arbitrary shape, both convex and concave, can be built by using such operations as translation and rotation of a polyline or polygon. The algorithm is designed to be able to run even on personal computers. The CPU time for an IBM AT is in the minute range for scenes composed of 400–500 faces. The program package can thus be used effectively in those cases when shaded images are not very complicated, short processing time is of primary importance and there is no need for pictures of “realistic” quality. Possible fields of application are animation, technical drawings and simulation.     

Machining of micro-systems

An increasing trend towards miniaturization of mechanical components necessitates the further development of micro-machining techniques in order to produce components within given tolerances. For the dressing of multilayered, metallically bonded, fine-grained grinding wheels that are used for micro-grinding the technique of electro contact discharge dressing was developed. In the following, the determined interrelations between the variables dressing voltage, limitation of dressing current, infeed and feed of electrode, and the volume flow rate in conditioning as well as the quality factor in conditioning are presented and illustrated. Thanks to the development of new geometries of CVD-diamond micro-grinding-pencils, a reduction of edge disruptions as well as a reduction of tool diameters to a minimum of 250 μm for the machining of brittle materials could be achieved. For the micro-drilling of ductile materials the maximal drilling depth could be increased by means of an adjusted process control. The smallest examined drill diameter was 50 μm. The utilizability of the developed processes and tools was proven in the production of aerostatic micro-bearings in the scope of the collaborative research center (SFB) 516.     

…On the direct programming of CNC milling equipment

This paper discusses the use of expert software which directly programs Computer Numerical Control (CNC) milling equipment from engineering style Computer-Aided-Design (CAD) drawings. Currently available software provides only semi-automatic programming based upon strict drawing format, user selected tools and user supplied tool path information. (DPS) derives part feature, tool selection, and tool path from “loosely” specified CAD drawings without direct user control. Other CNC programming methods are error prone and are slow to produce accurate CNC programs. The new technology eliminates programming error and completes processing in seconds rather than hours or days, thus providing for a true Computer Integrated Manufacturing (CIM) environment. DPS is in use on various 2D and 3D milling environments as well as on several types of small or personal computers and CAD systems. Additional systems and environments can be supported. DPS is designed to operate efficiently with AutoDesk, Inc.'s AutoCAD and Hewlett Packard 9000/320 ME-10 (HP-UX) based drawings. An additional implementation is running on SCO XENIX/386.

This paper presents technology and productivity improvements for various classes of DPS systems available today. Examples of actual use, productivity improvements and product dependencies are discussed and illustrated.     

Internal reinforcement in a connectionist genetic programming approach

Genetic programming (GP) can learn complex concepts by searching for the target concept through evolution of a population of candidate hypothesis programs. However, unlike some learning techniques, such as Artificial Neural Networks (ANNs), GP does not have a principled procedure for changing parts of a learned structure based on that structure's performance on the training data. GP is missing a clear, locally optimal update procedure, the equivalent of gradient-descent backpropagation for ANNs. This article introduces a new algorithm, “internal reinforcement”, for defining and using performance feedback on program evolution. This internal reinforcement principled mechanism is developed within a new connectionist representation for evolving parameterized programs, namely “neural programming”. We present the algorithms for the generation of credit and blame assignment in the process of learning programs using neural programming and internal reinforcement. The article includes a comprehensive overview of genetic programming and empirical experiments that demonstrate the increased learning rate obtained by using our principled program evolution approach.     

Boolean operations for 3D simulation of CNC machining of drilling tools

This paper addresses the simulation of drilling tools CNC machining. It describes a novel approach for the computation of the boundary representation of the machined tools. Machining consists of a sequence of boolean operations of difference between the tool and the grinding wheels through time. The proposed method performs the dynamic boolean operations on cross sections of the tool and it reconstructs the 3Dmodel by tiling between the cross sections. The method is based on classical computational geometry algorithms such as intersection tests, hull computations, 2D boolean operations and surface tiling. This approach is efficient and it provides user control on the resolution of the operations.     

基于Attention-LSTM的CNC刀具破损在线检测系统

为了在数控（CNC）机床批量加工过程中对刀具破损进行检测以减少残次产品,提出一种利用机床主轴功率信息,基于Attention-LSTM的CNC生产线刀具破损在线监测方法。该方法以数控系统内置传感器作为数据源获取机床主轴功率时间序列,在数据采集环节中,需要分辨加工过程中的不同工序以及该工序所使用的刀具编号。因此,在数据采集环节中,同时对数控代码和主轴功率进行采集,使用数控代码解析方式对采集数据进行处理,完成加工过程的工序识别,再使用Attention-LSTM算法对主轴功率数据进行预测,然后利用DTW算法计算时间序列相似度。加工过程功率时间序列和标准时间序列之间的相似程度应当处于合理的阈值范围内,否则认为此次加工过程中发生刀具破损。以FANUC数控系统为平台进行实验,验证了刀具破损识别的准确率。     

Programmable Rewriting Strategies in Haskell: — White Paper —

Programmable rewriting strategies provide a valuable tool for implementing traversal functionality in grammar-driven (or schema-driven) tools. The working Haskell programmer has access to programmable rewriting strategies via two similar options: (i) the Strafunski bundle for generic functional programming and language processing, and (ii) the “Scrap Your Boilerplate” approach to generic functional programming. Basic rewrite steps are encoded as monomorphic functions on datatypes. Rewriting strategies are polymorphic functions composed from appropriate basic strategy combinators.We will briefly review programmable rewriting strategies in Haskell. We will address the following questions:

• What are the merits of Haskellish strategies?

• What is the relation between strategic programming and generic programming?

• What are the challenges for future work on functional strategies?