Part Of Program Research Articles

Adaptive Control for the Metal Cutting Process

The adaptive control of metal cutting processes is a logical extension of the CNC systems. In CNC systems of metal-cutting processes the machining variables (e.g., the cutting speed and feedrate) are prescribed by the part programmer. The determination of these variables depends on experience and knowledge regarding the workpiece and tool materials, coolant conditions, and other factors.The determination of these operating parameters depends on experience and knowledgeregarding the workpiece and tool materials, coolant conditions, and other factors. By contrast,the main idea in adaptive control is the improvement of the production rate, or the reductionof machining costs, by calculation and setting of the optimal operating parameters duringmachining itself. This calculation is based upon measurements of process variables in real time and is followed by a subsequent on-line adjustment of the machining variables subject to constraints with the objective to optimize the performance of the overall system.The adaptive control is basically a feedback system, in which the operatingparameters automatically adapt themselves to actual condition of the process. AC system formachine tools can be classified into two categories:1.Adaptive control with optimization(ACO);2.Adaptive control with constraints(ACC);ACO refers to systems in which a given performance index (usually an economicfunction) is extremized subject to process and system constraints. With ACC, the machiningparameters are maximized within a prescribed region bounded by process and systemconstraints, such as maximum torque or power. ACC systems, however, do not use aperformance index. In both systems an adaptation strategy is used to vary the operatingparameters in real time cutting progresses. Although there has been considerable research onthe development of ACO systems, few, if any, of these systems are used in practice. The major problems with such systems have been difficulties in defining realistic indexes of performance and the lack of suitable sensors which can reliably measure on-line thenecessary parameters in a production environment. The objective of most AC systems isimprovement in productivity, which is achieved by increasing the metal removal rate (MRR)during rough cutting operations. The increases in productivity range from approximately 20 to 80 percent and clearly depend on the material being machined and the complexity of the part tobe produced.

Using multiple performance index for best-fitted design of computer numerical control turning process

ABSTRACT Typically, the turning process to be executed using turning machine tools is designed by experienced part programmers; however, the cutting efficiency and trade-off of the dimensional accuracy in the machining process present issues that may be difficult to deal with. Therefore, this study aims at systematically realizing a best-fitted design for the computer numerical control (CNC) turning process by referring to multiple performance indices, such as machining time, machining energy, surface roughness, and radius error. First, the turning process notation and performance evaluation index are defined according to the common side-change process, tool-change process, machining process, and machining results of the turning process. Next, the turning process map is established by the defined turning process notation; here, the comparison table of the total performance index (PI) consisting of the machining time, machining energy, surface roughness, and radius error is calculated and established. Finally, the best-fitted turning process satisfying the cutting efficiency requirement or dimensional accuracy requirement is selected according to the PI comparison table. The results obtained from the experiments performed on a CNC turning machine tool demonstrate that the best-fitted turning process can shorten the machining time by 39.04% (estimated machining time) and 34.24% (actual machining time).

The health of pregnant female migrants: analysis and possibilities of management

The analysis of the results of complex study of health ofpregnant female migrants demonstrated that their health condition is significantly worse than in comparison group. The most of female migrants suffered from complications during pregnancy and delivery. The percentage of newborns delivered by female migrants without pathologic manifestations was 1.3 times less in comparison with similar percentage in women from comparison group. The developed situation is in many ways is caused by more unfavorable conditions of work and life of female migrants. Besides, it was established that percentage of female migrants without observation in maternity clinic was 19.7 times higher the similar percentage of women from comparison group. The registration prior to 12 weeks ofpregnancy was marked only in every forth female migrant. The percentage of female migrants with biochemical screening applied was three times lower. The analysis of medical social problems ofpregnant female migrants permitted to develop proposals related to management of their health at the expense of amelioration of medical social care including number of organizational, social and medical activities. The experts determined priorities in realization of proposed activities. The developed activities can be used as a background of program on health support of pregnant women from families of migrants as am integral part ofprograms ofpopulation health support.

Mapping insecticide resistance in Anopheles gambiae (s.l.) from C\xf4te d\u2019Ivoire

BackgroundInsecticide resistance in malaria vectors is an increasing threat to vector control tools currently deployed in endemic countries. Resistance management must be an integral part of National Malaria Control Programmes’ (NMCPs) next strategic plans to alleviate the risk of control failure. This obviously will require a clear database on insecticide resistance to support the development of such a plan. The present work gathers original data on insecticide resistance between 2009 and 2015 across Côte d’Ivoire in West Africa.MethodsTwo approaches were adopted to build or update the resistance data in the country. Resistance monitoring was conducted between 2013 and 2015 in 35 sentinel sites across the country using the WHO standard procedure of susceptibility test on adult mosquitoes. Four insecticide families (pyrethroids, organochlorides, carbamates and organophosphates) were tested. In addition to this survey, we also reviewed the literature to assemble existing data on resistance between 2009 and 2015.ResultsHigh resistance levels to pyrethroids, organochlorides and carbamates were widespread in all study sites whereas some Anopheles populations remained susceptible to organophosphates. Three resistance mechanisms were identified, involving high allelic frequencies of kdr L1014F mutation (range = 0.46–1), relatively low frequencies of ace-1R (below 0.5) and elevated activity of insecticide detoxifying enzymes, mainly mixed function oxidases (MFO), esterase and glutathione S-transferase (GST) in almost all study sites.ConclusionThis detailed map of resistance highlights the urgent need to develop new vector control tools to complement current long-lasting insecticidal nets (LLINs) although it is yet unclear whether these resistance mechanisms will impact malaria transmission control. Researchers, industry, WHO and stakeholders must urgently join forces to develop alternative tools. By then, NMCPs must strive to develop effective tactics or plans to manage resistance keeping in mind country-specific context and feasibility.

Contour maps for developing optimal toolpath and workpiece setup in hexapod machine tools by considering the kinematics nonlinearity

Contrary to the conventional serial kinematics machine tools, the parallel kinematics machine tools exhibit nonlinear behavior which is a major source of the machining error. This causes even a linearly programmed path to be traversed along a nonlinear path. The resulting error, known here as the kinematic error, should be critically considered during the toolpath planning. The estimation of the maximum kinematic error using the concept of median osculating circle is introduced in this article. The proposed formulation demonstrates that the maximum kinematic error depends on the curvature of the actual trajectory. In order to estimate the curvature, constant curvature contour maps are introduced. These maps depend on the structural parameters of the machine and are recommended to be provided by the machine’s manufacturer. The constant curvature contour maps are illustrated to be an effective graphical tool for kinematic error estimation and thus successfully conducting the optimal planning of the toolpath and the workpiece setup. Consequently, it is recommended in this article that the constant curvature contour maps be employed in the format of a database by computer-aided manufacturing systems during toolpath planning and by interpolators during command generation or by a part programmer to optimally setup the workpiece or conduct the toolpath planning such that the least kinematic error occurs during the machining.

Novel dutch self-assessment biosecurity toolkit to identify biorisk gaps and to enhance biorisk awareness.

Life sciences, biotechnology, and medicalbiologyareindispensableresearchfieldsforpublic health and the development of ther-apeutics and vaccines. However, biologicalagentsandinformationdevelopedtobetterhealth, welfare, and safety, could be mis-usedforharmfulpurposestocausedamageto public health, safety, and the environ-ment (1–3),which is termed the“dual-use”aspect of research in the life sciences. Lab-oratory biosafety describes containmentprinciples, technologies, and practices toprotect people from biological agents, andprevent accidental release of biologicalagents (4). In addition to biosafety, labo-ratory biosecurity measures aim to preventtheft and intentional or malicious use ofbiological agents (4). Thus, both biosafetyand biosecurity should be an integral partof program management of organizationshandling dangerous pathogens, in order toprevent potential dual-use research, unde-sired spread, theft, malicious use, andbioterrorism.

Energy-efficient distributed part programme for highly automated production systems

Distributed part programmes (PPs) across the shop-floor resources have been identified as a possible enabler of production flexibility, while the energy assessment has been recognised as a relevant factor for the global sustainability. This article proposes a distributed PP approach, identified as network part programme (NPP), while addressing the minimisation of system energy consumption. The approach, called energy-based NPP, is based on two mathematical models. The first model generates a number of alternative pallet configurations according to the minimisation of workpiece set-ups and energy consumption. The second model grants the energy consumption threshold at system level through the selection of previously-generated and alternative workplans. The application of the approach on a real case shows a reduction of the energy consumption, the respect of the system energy consumption threshold and a substantial improvement in operational costs compared to traditional workplan design methods.

Computations for Simplification of Canned Cycles in CNC Programming for Turning Operations

Canned cycles are predefined machine instructions stored permanently in the machine controller. These are used while writing part program to perform machining operations that are of repetitive nature. Whenever G & M code for these canned cycles appeared in part program, the controller of the machine calls already stored instructions and executes. However all CNC machines may not have facility to run part programs with canned cycles due to lack of computational facilities. The developed utility in this program allows part programmers to write part program using canned cycles and later on convert them in simplified programs to run on the low cost CNC machines. Present work deals with computations required to convert a canned cycle into linear interpolation based on the machining parameters assigned in that canned cycles. Developed code reads the CNC part program and extracts the desired points from presented canned cycles and perform desired geometric computations to converts it into simple part programs with elimination of canned cycles and writes in another text file in the form of a part program. Developed system is user friendly and made available online for users at http://virtualcnc.iiitdmj.ac.in. It implies a web based online client-server architecture which facilitates user to send their own CNC part programs with canned cycles at server site via internet and get the simplified part program which contains only linear interpolation at their end. Therefore the developed utility in this work can also provide an interface/exchange program for part programs between various CNC machines of different make.

Tool Posture Optimization Subjected to the Rigidity of Multi-Axis Machine Tool

In order to achieve higher product quality for sculptured surface productions, an advanced strategy are proposed for machining planning, namely a tool-posture-control strategy. In the tool-posture-control strategy, machining chatter is reduced by controlling the machine rigidity along cutting feed direction. This proposed strategy, which improved product quality of sculptured surface when subjected to both the part geometry and the machine rigidity constrains, is described in this paper. A new machining-planning aid called local stiffness index is developed to help tool posture planning. This proposed strategy subjected to multi-constrains help a part programmer to choice the optimum tool posture. In order to illustrate the application of stiffness index map and the proposed strategy, the applications of the proposed strategy to real three-dimensional complex surface (e.g. a turbine blade) are presented in this paper.

The Geometry and Generation of NC Tool Paths

Numerically controlled milling is the primary method for generating complex die surfaces. These complex surfaces are generated by a milling cutter which removes material as it traces out pre-specified tool paths. The accuracy of tool paths directly affects the accuracy of the manufactured surface. The geometry and spacing of the tool paths impact the scallop height and time of manufacturing respectively. In this paper we propose a new method for generating NC tool paths. This method gives the part programmer direct control over the scallop height of the manufactured surface. The method also provides options to the part programmer for generating a variety of tool paths based on practical metrics such as tool path length, tool path curvature and number of tool retractions.

Integrated planning for precision machining of complex surfaces. Part 1: Cutting-path and feedrate optimization

In order to achieve higher productivity and product quality simultaneously for sculptured surface productions, two advanced strategies are proposed for machining planning, namely a cutting-path-adaptive-feedrate strategy and a control surface strategy. In the cutting-path-adaptive-feedrate strategy, machining time is reduced by cutting along low-force-low-error machining directions and by maximizing feedrates. In the control surface strategy, machining errors are minimized by using a compensated control surface based on predicted machining errors. In part 1 of this paper, the cutting-path-adaptive-feedrate strategy, which improves the productivity of sculptured surface machining when subjected to both force and dimensional constraints, is described. In this proposed strategy, a new machining-planning aid called a maximum feedrate map is developed. In this map, the maximum allowable feedrates, subjected to the specified constraints, at each control point along various machining directions, are determined using a surface generation model. These local maximum-feedrate boundaries indicate the acceptable range of feedrates that a part programmer can use in the NC programming. In addition, the maximum feedrate map also provides the part programmer an important aid in selecting the cutting directions. In order to illustrate the application of the maximum feedrate map and to examine the capability of the proposed cutting-path-adaptive-feedrate strategy in improving the productivity of sculptured surface machining, simulation studies of a two-dimensional curved surface are performed and the results are presented in this paper. The applications of the proposed strategy to real three-dimensional complex surfaces (e.g. a turbine blade die) along with experimental verifications are presented in part 2 of this paper. In part 3 of this paper the control surface strategy and its applications to the finish milling of three-dimensional complex surfaces are discussed.

Machining surfaces composed of cyclide patches

Cyclide surfaces have attracted the attention of CAD/CAM researchers in the last decade. Thus far, the main focus of research in cyclides, has been its use in shape design. In this paper we consider the problem of generating NC tool paths for machining parts designed with cyclide surfaces. We describe details of generating three kinds of cutter paths — planar section, iso-parametric and iso-curvature tool paths. We also propose metrics for evaluation of cutter paths. These methods have been implemented in a prototype system. The design module of the system (not dealt with in this paper) allows the user to construct free form surfaces composed of cyclide patches. Using the machining module, described in detail in this paper, a part programmer has the option to generate the aforementioned tool paths. In addition to the algorithmic details, we provide examples of implementation and fabrication of physical prototypes.

Knowledge-based approach for improvement of CNC part programs

In typical CNC machining processes, a CNC program specifies machining parameters and geometrical data. Part programmers usually write CNC programs based on their experience and perception. Because humans may not be able to sense physical quantities with high accuracy, modern CNC machines are equipped with a variety of sensors to indicate machining conditions. But modern sensing systems and human expertise are separated in most existing systems. Run-time information does not contribute to CNC program quality. This paper attempts to illustrate the structure for coordinating sensing data and expert knowledge to tune the CNC program. The turning process is done through both knowledge reasoning and mathematical processing. Simulation demonstrates convergent results of tuned feed rate under the tool deflection constraint.

A design approach for constructing engineering scenario maps

We present a cognitively based design approach for the staged construction of a high level linguistic-visual map useful for engineering scenario analysis. This map, which we call a Three Dimensional Conceptual Thematic Map (3D-CT Map), is a linkage of a 3-Dimensional geometric Map (3D-Map) and a semantic net which we have called a Conceptual Thematic Map (CT-Map). The 3D-CT Map is an attempt to specify what is in the environment, where it is, and what is happening to it. The CT-Map component is derived by combining information from two explicit linguistic levels, syntax and semantics. It consists of recursively nested semantic structures linked by thematic roles. The 3D-Map component is derived by combining the information from two explicit visual levels, the 2 1/2 D sketches (which correspond to standard engineering drawings) and three dimensional shape models. The result of these visual combinations is the 3D-Map which shows the object centered three dimensional geometric component of the scenario. Annotating the 3D-Map with selected cross references to the CT-Map constitutes the 3D-CT Map. The theoretical bases of the 3D-CT Map rest on the combined insights of contemporary vision and linguistics researches, principally Ray Jackendoff and David Marr. These linguistic and vision insights are founded on a representationalist view of human understanding and action that includes the formal recognition, analysis, and constructive representation of autonomous levels of mental information structures. Each level of representation has its own set of primitives, well-formedness rules, and links to other levels via inter and intra level correspondence rules. At an even more fundamental level, these insights are in consonance with a view of the human mind/brain as a biological information processor. We illustrate this cognitive design approach by constructing a 3D-CT Map from a scenario drawn from the spatial domain of Numerical Control Part Programming. The inputs to the derivation consist of engineering drawings, a natural-language scenario description of the procedure to be carried out, and the experience of the part programmer. The outputs from the scenario analysis process are: syntactic parse trees, semantic structure graphs, annotated semantic structure graphs (i.e., the CT-Map), 2 1 2 D sketches of the geometry of the scenario (i.e., engineering drawings), a 3D-Map of the scenario geometry, and finally, a synthesized map of the scenario that links these components together i.e., the Three Dimensional Conceptual Thematic Map.

Survival in space: medical problems of manned spaceflight

List of Illustrations Preface Acknowledgements Abbreviations A Note about Units Part 1 Introduction: 1. The Nature of Space 2. The Manned Spaceflight Programmes Part 2 Putting Man Into Space: 3. Pressure and Density 4. Increased Accelerations 5. Radiation and Micrometeoroids 6. Temperature and Humidity 7. Nutrition, Waste, and Personal Hygiene 8. Dressing for Space and Mobility 9. Health Care 10. Selection and Training Part 3 Keeping Man in Space: 11. Decreased Accelerations: Microgravity 12. The Psychology of Spaceflight, Women in Space, and Spacecraft Habitability 13. The Future Bibliography Glossary Index.

Development of an expert system for machinability data selection

An attempt has been made in this study to develop an expert system for machinability data selection to assist part programmers and process planners in their decision making processes for toolholders, inserts and cutting conditions with future extension to an integrated machining system. The procedures to arrive at the appropriate solutions are encoded from factual and procedural knowledge stored in a knowledge bank. As such the knowledge bank plays an important role in providing valued information and differs from the existing data bank concept.

Assuring confident re-use of production drawing information by the NC programming activity

In the heavy/medium manufacturing environment, the generation of NC part programs is a prolific and productive element of CAM. With the increasing use of computer-aided drafting a more effective and automatic method for the generation and transcription of manufacturing instructions and information has become available. The creation and maintenance of a computer graphics database, containing master component definitions, can facilitate the automatic re-use of graphical information by NC part programmers. However, near automatic data re-use can only be accomplished by maintaining the integrity of manufacturing information stored in the database, ensuring the correlation between such data and the associated conventional presentation of manufacturing data as traditional orthographic production drawings.

CAD/CAM System at Nissan Motor

The CAD/CAM system has been established mainly in the field of automotive body sheet metal engineering. The system is a combination of large host mainframes, interactive graphics, on-line plotters and NC machines. The realized CAD/CAM system fulfills the following: (1) The automotive body surfaces are defined by a complete mathematical model. Original data of the model is taken from a clay model. As the result, press tools can be made quickly and precisely using NC techniques. (2) Drawings of body sheet metal are originated on the graphics computer. This data is available to other engineers, such as structural analysts and NC part programmers. (3) In addition, this system is the best tool for helping engineers examine wiping area of windshield, movement of side glass, volume of fuel tank, validity of wiring diagram and so on. This paper covers the key elements of CAD/CAM at Nissan Motor Company.

A computer‐aided design system for NC part program

Abstract The paper is concerned with the development and implementation of a computer‐aided design of NC part programs by using a high‐level computer language. The system thus developed is termed NCTCAS processor. The blueprint of a workpiece is converted readily by using part description language into a compatible form as the input. The information input is processed by the NCTCAS processor. The output of the system contains the desired NC part program and a machine setup information. The part program is intended to be used by the NC machine tool; the machine setup information tells the machine operator to prepare tools needed and the turret setup, etc. A case study to illustrate the usage is reported. The purpose of the system is to save the NC part programmer time and effort for preparing the program.

A high‐level language for numerically controlled cutting machines used in shipyards

Abstract Numerically controlled (N/C) flame cutting machines have been extensively used in modern shipyards to cut steel plate according to a given contour. This paper presents a geometry description language CSBL‐1.0 to describe contours of shipbody parts. Its language processor is designed to interpret part programs in this language to generate N/C code for controlling the cutting machines. The part programmers coding in this language can essentially mimic the procedure of contour drawing. It is easy to learn and easy to use. Furthermore, part programs in this language are more comprehensive than the corresponding N/C numerical codes and hence they can be easily debugged and maintained. Also, coding in this language can essentially be relieved from mostly tedious and error‐prone geometrical calculations, which are rendered to the language processor. Techniques in automating these calculations are presented. Finally, some possible future extensions are discussed. This language, which has been field‐teste...