Search

Summary As global warming intensifies, emerging evidence has demonstrated high ambient temperature during pregnancy negatively affects maternal physiology with compromised pregnant outcomes; however, little is known about the roles of gut microbiota and its underlying mechanisms in this process. Here, for the first time, we explored the potential mechanisms of gut microbiota involved in the disrupted glycolipid metabolism via hepatic mitochondrial function. Our results indicate heat stress (HS) reduces fat and protein contents and serum levels of insulin and triglyceride (TG), while increases that of non‐esterified fatty acid (NEFA), β‐hydroxybutyric acid (B‐HBA), creatinine and blood urea nitrogen (BUN) (P

In order to guarantee machining quality and production efficiency and as well as to reduce downtime and cost, it is essential to receive information about the cutting tool condition and change it in time if necessary. To this end, tool condition monitoring systems are of great significance. Based on the data fusion technology of multi-sensor integration and the learning ability of deep residual network, a tool wear monitoring system is proposed in this paper. For data acquisition, multiple sensors are used to collect vibration, noise and acoustic emission signals in the machining process. For signal processing, the data fusion method of angular summation of matrices is used, so that the multi-source data are fused into two-dimensional pictures. Then, the feature extraction module of the proposed system uses the pictures as input and takes advantage of the deep residual convolutional network in extracting the deep features from the pictures, and finally the identification module completes the recognition of the tool wear type. To verify its feasibility, a testing bed is built on a CNC milling machine, and multi-sensor data are collected during the machining process of a simple workpiece with one of the two selected cutting tools each time. The proposed system is trained using the collected data and then is used to monitor the wear condition of a new cutting tool by collecting real-time data under similar condition. The results show that the accuracy of wear state recognition is as high as 90%, which verifies the feasibility of the proposed tool wear monitoring system.

Whirling has been adopted for the cost-effective machining of blade-shape components in addition to traditional end milling and flank milling processes. To satisfy the requirements of rotary forming in the blade whirling process, the workpiece must be clamped at both ends in suspension and rotated slowly during machining, which complicates the dynamics. This study aims to identify the dynamic characteristics within the blade whirling operation and present strategies for stability prediction. In this study, the dynamic characteristics of a whirling system are modeled by assuming symmetric and asymmetric parameters. Theoretical prediction frequency response function (FRF) results are compared with experimental results. Moreover, semi-discretization stability lobe diagrams (SLDs) obtained using the dynamic parameters of these models are investigated experimentally. The results show that the asymmetric model is more suitable for describing the whirling system, whereas the symmetric model presents limitations associated with the frequency range and location of measuring points. Finally, a set of airfoil propeller blade whirling operations is conducted to verify the prediction accuracy.

A propeller blade, as a typical example of low-rigidity components, is prone to chatter and deformation in machining process, especially when large material removal is applied. In order to foresee the problems and then optimize the process, identification of the dynamic behavior of the workpiece is of great importance. This paper studies the dynamic characteristics of the workpiece in the machining process from plate to propeller blade using Finite Element Method. The results show that the time-varying natural frequencies of the workpiece decrease gradually at the beginning steps of the process due to the influence of material removal, and increases afterwards influenced by the geometry of the blade.

Invented decades ago, whirling is a machining process primarily employed for producing helical surfaces. In view of its cost-effectiveness, this paper proposes to adapt the whirling process for manufacturing airfoil blades. Considering that chatter often occurs during the whirling process due to the low stiffness of blade workpiece, which impairs the machining quality, theoretical issues in relation to chatter and its prediction for the blade whirling process are investigated. Firstly, the principle of blade whirling is briefly introduced and vibration components in the cutter-workpiece system are analyzed in order to identify the characteristics of blade whirling and establish a reasonable dynamic model. Then, a theoretical model for stability prediction in blade whirling is presented and verified, which fully considers the geometric immersion of the whirling cutter and the dynamic parameters of the workpiece system. In order to ensure accuracy of the prediction results, non-symmetric frequency response function (FRF) matrices are adopted in modeling the system and identifying the modal parameters. After that, the effect of material removal on machining stability is examined. Since a large proportion of material is to be removed, the whirling operation is divided into several steps for exploration. The results show that the material removal changes the natural frequency and modal shape of the system which causes the variation of the limit on cutting depth. Finally, the proposed approach is verified with a scaled propeller blade being machined as a case study.

The placenta is critical for the regulation of fetal innate immune function. Maternal heat stress (HS) impairs the immune function and the intestinal barrier in the offspring. However, the effects of maternal HS on the placental immune response and the development of the fetal intestine and its innate immune system remain unclear. Fetal mice were divided into the utero control (IUTN) and heat stress (IUHS) groups according to the maternal ambient temperature. Transcriptome analysis revealed that the expressions of placental immune response–related genes such as macrophage antigen CD68 and Fc gamma receptors 1 and 3 (fcgγ1 and fcgγ3) were increased, but the mRNA expression and protein levels of colony-stimulating factor-1 (Csf1) were decreased in the HS group compared with the TN group (p < 0.05). Furthermore, there was no significant difference in the intestinal length normalized to pup weight between the IUTN and IUHS groups. The expression of genes (such as alpi and ttr) involved in fetal duodenum and jejunum development was downregulated by maternal HS, whereas the expression of genes enriched in the cell cycle was increased. The mRNA expression and protein levels of cell division cycle 6 (Cdc6) in the fetal duodenum and jejunum were much higher in the IUHS group than in the IUTN group (p < 0.05). Maternal HS also down-regulated the expression of genes enriched in the innate immune system in the fetal duodenum and jejunum. The mRNA expression and protein levels of interleukin 1 alpha (IL1a) were reduced in the IUHS group compared with the IUTN group (p < 0.05). Taken together, these data demonstrated that maternal HS modulated the expression of genes in the placenta related to the immune response and inhibited the development of the fetal intestine and its innate immune system.

A model validation methodology applicable to the advanced distribution management system is proposed, to guarantee the integrated common information model (CIM)-based distribution network model are reliable for the distribution management and optimization. The validation test rules for gross error detection, equipment unit consistency check, topology consistency check, time series consistency check and tempo-spatial consistency check are analyzed. A consistency check tool is implemented to apply the methodology. Finally, some results are obtained with the consistency check tool for a simulated case study to verify the proposed methodology

Tool wear does great damage to product quality and machining efficiency. In this paper, a new tool condition monitoring (TCM) method based on a multi-sensor data fusion imaging and attention mechanism is proposed to indirectly measure and monitor tool wear. First, the multi-sensor signals collected during the operation of the machine tool are encoded and fused. A novel triangular matrix of angle summation method is proposed to fuse multi-sensor time-series signals at the data layer and to image them as two-dimensional images. The method used here effectively retains the detailed characteristics of the data, and also effectively retains the internal time relationship of the signal. In addition, a deep residual network with a convolution block attention module is used to extract the deep features from the encoded image and identify the wear stage of the tool. The proposed deep-learning network is then applied to TCM. It selects information in the channel and spatial domains based on its attention mechanism, and increases network depth by combining residual blocks to realize deep feature extraction. Compared with traditional machine learning methods, this end-to-end deep learning model does not rely on feature engineering, which requires a lot of expert knowledge and artificial experience. In our experimental study, a public data set was used to train the model, and the results showed that the accuracy of the model proposed in this paper was as high as 94%. To further verify its feasibility and effectiveness, the proposed model was also compared with other methods.

Widely increased use of screws with variable pitch, flight and core in contemporary machinery makes it of great significance to explore an efficient way for manufacturing them. This paper proposes a whirling-based approach to manufacturing bespoke screws of kind. The machining is performed on a 3-axis CNC whirling machine. Unlike conventional whirling process which uses profiled cutters to cut the helical grooves, this approach employs tipped cutters which follow complicated toolpath to cut the screw out of a blank. In order to determine a continuous toolpath to approximate the screws cross-section profiles, one after another, the screw's cross-section profiles are considered as the envelope of the tipped cutters' trajectory and m CC points on each cross-section are relocated at several hypothetical cutting planes evenly. Finally, machining test using an example screw part is conducted to demonstrate the feasibility of the proposed approach. [Submitted 29 December 2018; Accepted 27 February 2019]

In order to improve the design and manufacturing efficiency of propellers, a dedicated CAD/CAM system for the whirling process of propeller blades is proposed. The main functions of the proposed system include parametric modeling of propeller blades and tool path solution for the whirling process of the blade. The former takes advantage of Creo to construct propeller’s 3D model by means of parametric modeling of the original design data; the latter is aimed to help manufacture the propeller blades using whirling process which is primarily used in producing threaded parts.

Comprehensive information model describes all objects relevant to the process of electric power production. The resource of power system could be depicted through the class, property and the relationship of these objects. In order to satisfy the requirements of interoperability and insertion compatibility for the power system, the paper provides a smart distribution comprehensive information model analysis and data repair technology based on the CIM model of power system using the UML class diagram. It also introduces the design process and the framework of this technology. Meanwhile, this paper also studies the shortest pathway among classes based on breadth-first search algorithm used to find the connection relationship between different classes and proposes a simplification rule to simplify the connection relationship. Finally, the realization effect of distribution power network model construction and data repair system is exhibited in the paper.

With the wide use of complex helical surfaces in screw components, it becomes more and more urgent to investigate efficient ways for the design and manufacture of components of this kind. This study establishes the mathematical model of helical surface based on discrete points on its axial section profile using cubic spline curve fitting method, and presents a theoretical approach to calculate the tool path for the whirling process which aims to produce the helical surface through enwrapping movements of standard cutters inserted in the tool ring. The approach is implemented in MATLAB environment focusing on the calculation of the cutter location points. After that, the theoretical machining error is analyzed focusing on the scallop height, which can be divided into axial and cross-sectional errors. Finally, a case study is provided, together with numerical simulation demonstrating the validity of the proposed approach.

Widely increased use of screw components with complex helical surfaces in contemporary machinery makes a huge demand for high-efficiency fabrication of these components. In this paper, a typical whirling process is introduced and the helical surface of a screw shaft is mathematically modeled based on its axial section profile, which is depicted usually by a number of sampled points. Following this, a theoretical approach is proposed to whirling the screw by using standard cutters, aligned with a detailed investigation into related issues including calculations of the cross section profile and the cutting tool location points. In this approach, the helical surface can be generated according to the shaft cross section which is used as the envelope of the cutting-tool motions in the machining process. The machining error is also analyzed with focuses on the axial- and cross section scallop height. Finally a case study is presented, which demonstrates the whole process including CAD models and cutting tool in-process positioning geometry data. The error distribution of the machined component along the profiles is also simulated.

Nowadays, Ethernet networks have been extended down into the field of automation control from the upper planning and scheduling level, which caused the generation of a new form of communication using real-time industrial Ethernet fieldbus. This paper presents a feasible Ethernet-based real-time feildbus scenario for industrial automation control systems. It endeavours to gain high performance in general synchronisation real-time control systems with common hardware and software resources. For this purpose, a master-slave pattern is adopted in constructing the communication protocol. The slave nodes are developed based on universal FPGA and ARM chips, and the first slave node is in charge of precise cyclic timing and synchronisation among all slave nodes with time resolution of 20 nanoseconds. The master protocol stack is developed under Linux using Real Time Application Interface RTAI, which not only provides application interface for user programs but also is responsible for exchanging process data with slave nodes in real time. A case study of merging this fieldbus into EMC2 to control a three-axis milling machine is also discussed and implemented. The experiment results show that this industrial Ethernet fieldbus platform completely meets the demand of open industrial automation control application.

With the globalisation of manufacturing industry, extendable and networked computer numerical control systems that can support bidirectional and seamless data exchange are in urgent need. This paper presents a STEP-NC compliant controller based on Real-time Ethernet technologies, which consists of functional modules such as General Interpreter, Machining Manager, Tool Path Generation, Machine Tool Model, Simulation and Real-Time Ethernet Interface. The proposed controller is implemented for circuit board milling. In the controller, STEP-NC is utilised as the data format, as well as a part of the controller's software structure. The late binding together with object oriented polymorphism and iteration, which can accomplish general functions, is used in developing the interpreter. This, together with the Reflection mechanism, also realises the general function of creating and modifying some of the STEP data. This controller is then tested on a circuit board milling machine, with ISO 14649 files generated by a CAM module developed in association with this work, in which some AP210 entities are added to represent circuits’ geometry and translated to machining features in the STEP-NC format. Moreover, machining a single feature with multi tools is discussed and the concept of final features is adopted; all contribute to some effective milling strategies.

Heating exchange in district heating network is a complex process with great inertia and longtime delay, it is hard to control the temperature of secondary supplying water effectively with traditional PID controllers. This paper studies the fuzzy PID method and models the heat exchanger system through combining the fuzzy control algorithm with the traditional PID method. Meanwhile, simulation experiments of the fuzzy controller, which is based on the MATLAB/SIMULINK platform, is performed in detail .The results of the simulation show that this control strategy has characters of faster response and strong robustness. It is appropriate for controlling the temperature in district heating network.

Over the last 50 years, there have been many significant enhancements in computer aided systems which have influenced the CNC technology. One area that can be considered as a bottleneck to these CNC enhancements, and in particular to interoperability in CNC manufacturing is G&M part programming (ISO 6983). To overcome this bottleneck, the new standard ISO 14649, known as STEP-NC, is being developed to provide detailed information on component design, process planning and machining strategies to manufacture parts for the next generation of intelligent CNCs. This standard forms the basis of a new paradigm shift in the CNC domain to support digital modelling of CNC manufacturing resources. The research in this paper aims to identify major issues and develop new software tools to demonstrate the feasibility of interoperable CNC manufacturing based on STEP-NC. Besides the literature review on recent research and development on STEP-NC, this paper proposes a Process Planning System (PPS) with surface roughness chosen as the process planning objective. PPS consists of five modules: program reader, process planner, STEP-NC CAD viewer, STEP-NC CAM viewer and program writer. The reader is responsible for interpreting the geometry and the manufacturing data from a STEP-NC text file into a stored data list. The process planner uses this data list and enables users to evaluate surface roughness based on a mathematical model. Through the STEP-NC CAD viewer, the part geometry can be shown and via the STEP-NC CAM viewer the toolpath can be verified. Finally, the writer converts the stored STEP-NC data of the system into an updated STEP-NC file. An example case study component is used to demonstrate the PPS and show the interfacing of the STEP-NC data.

ISO 6983 has now been considered as a bottleneck for developing next generation CNC machine tools. STEP-NC is a new interface standard between CAD/CAM systems and CNC machines, which not only provides an object-oriented data model for CNC with a detailed and structured data interface that incorporates feature-based programming, but also represents a data model for intelligent computer numerical controllers. This paper presents a conceptual framework of holonic compliant data interference for numerical control STEP-NC controller to implement intelligent control for Computer Numerical Control (CNC) machine tools. The architecture is comprised of 14 functional agents, such as interpreter agent, process planning agent, NCK/PLC agent, decision-making agent, etc. These agents can co-operate closely to carry out various functions of the intelligent STEP-NC controller in a desired manner. The process flow for the STEP-NC controller is analysed. Furthermore, the implementation for two functional agents (i.e. inter...

In this paper, a new CNC core design method, the function-separated design (FSD) method, is proposed to increase the modularity and reconfigurability of CNC systems, simplify the CNC development process, as well as gain a secondary development ability to allow customers or third parties to add or modify NC functions at the shop floor level. With the FSD method, a new CNC core structure is built. In this structure, the CNC core is composed of three main components: engine machine interface, event processor (EP), and system description data (SDD). The engine machine interface provides an interface to machine tools through the parameter settings via a human machine interface (HMI). The EP and SDD are the most important parts. The SDD stores the control rules and modularized NC functions. It is designed as the relatively separated part inside the CNC core. It can also be modified according to the specification changes to access the functions of the CNC core at the shop floor level. To ease the modification of the SDD on the shop floor, the Statechart modeling tool is used to generate a CNC function model; meanwhile, an SDD generator is developed to convert this model into the SDD. The EP is driven by events from the event generator and processes these events by referring to the SDD. The EP always remains the same. With such a structure, the control rules and NC functions of a CNC core can be redesigned or upgraded easily. A case study for implementing a non-circular piston-turning system verifies the feasibility of the proposed design method at the shop floor level.

Special-shaped screws are widely used in industries. However, the approach to machining special-shaped screws with high working efficiency and high surface quality is still in pursuit. This paper studies the mathematical model of screws with variable leads, diameters and groove depths based on the general model and the formation mechanism of the common screw. After that, by the further study of the mathematical model of special-shaped screws and the cutting principle of whirling, the paper finds the way to calculate the tool path of screws with variable leads, diameters and groove depths which can be used to whirling machines. Ultimately, a actual work piece is successfully machined via whirling in experiment.

STEP-NC (ISO 14649) provides a new data interface for computer numerical control (CNC) machine tools. However, replacing the current ISO 6983 with STEP-NC is not only a matter of change in NC programming language but it also has a far-reaching and profound effect on the future CNCs and even on manufacturing systems. The CNCs are destined to evolve from pure controllers into integrated systems with both decision-making and control abilities. In this paper, strategies for implementing the STEP-compliant CNC systems are discussed and a framework for the autonomous STEP-NC controller is proposed. The controller is organized into two agents: the planning agent and the machining agent. This paper also provides a general discussion on issues about the part program interpretation, the on-line process planning. In order to support dynamic planning as well as meet the real-time requirements in NC machining, it is proposed to solve the on-line planning issues in two stages, i.e. the shop-floor planning and the real-...

On-Machine Inspection (OMI) is an effective way in NC machining processes to improve the quality of machined parts and reduce assistant machining time. In this paper, STEP-NC?ISO 14649?data model is introduced to the integration of NC machining and On-machine Inspection in order for Closed-loop Machining. First a STEP-NC Controller with OMI to realize integrated machining and inspection of parts is proposed, along with its architecture, functional modules and working procedure. Then the implementation method of such a system on Java platform is presented, and preliminary modules are developed including the interpreter, machining simulation and probing simulation. A case study of an example part is also provided focusing on the integration of the machining and the probing processes, which demonstrates the feasibility of the proposed STEP-NC Controller with OMI.

To implement STEP-Compliant CNC, the implementing platform is very important. How to design open, STEP-Compliant CNC software and hardware platform becomes a hot research topic. A lot of research was focused on the STEP-NC data pre-processing of the STEPCompliant CNC, but how to design flexible, open structure software and hardware platform for STEP-Compliant CNC implementing was not described in detail. In this chapter, the requirements of STEP-Compliant CNC system are analysed. Based on these requirements, an engine based platform is given as the software platform according to the reactive characteristic of the CNC system. In this platform, the software structure is designed as the Decision Unit (DU), Function Description Data (FDD) and System Engine (SE). The intelligent control rules and algorithms are designed in DU. The control rules of the NC functions are designed as the FDD, which works like a dictionary. FDD can use the resource of DU with specially designed Dynamic Link Library (DLL). SE is built upon this dictionary. When the system started, SE gives response to the stimuli according to the description of FDD. It can call the decision making functions through the description of FDD. Statechart method is used for the modelling of control rules, an FDD generator being designed to convert the modelling data of control rules to FDD. With this method, FDD can be easily derived. For this flexible software architecture, a corresponding flexible hardware platform is also designed. In this chapter, an Ethernet based industrial fieldbus is used for the hardware platform. The implementing details are given. With this design methodology, system upgrading can be easily done by simply regenerating of FDD and hardware reconfiguration.

Surface roughness and surface shape simulation are presented for the intelligent STEP-NC turning controller in this paper. Simulation models for surface roughness and surface shape were established. Graphic user interface (GUI) was developed to input the simulation parameters and output the simulation results. Simulating with the developed simulation models, some important conclusions were obtained. As a result, the surface roughness and surface shape simulation based on STEP-NC will aid the development work of the intelligent STEP-NC controller.

This paper presents a simulation system of intelligent STEP-NC Turning controller. Architecture of the STEP-NC turning simulation system was presented. Some key technologies to implement the simulation system including cutting force modeling, vibration modeling and surface roughness modeling were described in detail. Furthermore, graphic user interface (GUI) was developed to input the simulation parameters and output the simulation results. Simulating with the developed simulation models, some important conclusions were obtained. As a result, the numerical control simulation system based on STEP-NC provides a critical module to aid STEP-NC controller intelligently controlling the turning machining process.

Impeller blades are often constructed by non–developable ruled surfaces. Due to their twisted feature, the application of flank milling to these blades would inevitably cause significant interference between the cutter edge and the machined surfaces. In view of the advantages of flank milling operations, this paper proposes a combined approach to flank milling these blade surfaces with acceptable precision and fairly high efficiency. Centring on the minimisation of the interference, the non–developable blade surface is divided into a number of strips, the cutter profile is modified accordingly, and then the tool paths are calculated strip by strip. Along with the basic idea, related issues are investigated in detail focusing on the strip width determination, cutter profile modification, and cutter location calculation. For practical use of the proposed approach, necessary algorithms are also provided. Finally, a case study is presented, together with numerical simulation of the cutting process. The results show that the proposed approach is not only feasible but also much more efficient than the conventional point milling method. [Received 6 November 2013; Revised 16 June 2014; Accepted 2 October 2014]

Tomorrow's manufacturing workstation will be autonomous and intelligent with the ability to interpret geometric and manufacturing knowledge and automatically to manufacture components. STEP-NC is one of the building blocks that will support this endeavour for a new paradigm of the intelligent autonomous manufacturing. This paper outlines a framework for a STEP-NC controller, which represents one of the building blocks for tomorrow's manufacturing workstation. The conceptual controller consists of an interpreting module (interpreter), a planning module (planner), a simulation module and a CNC kernel. The interpreter reads an AP238 file and converts it into internal data, which the planner utilizes to sequence the specific machining operations and processes. The work illustrates the feasibility of the framework for interpreting STEP-NC information in an AP238 format and storing the data within a STEP compliant data structure for use in machine planning. The implementation tools and methods for interpreting ...

Computer numerical control (CNC) manufacturing has evolved with the use of faster, more precise and more capable CNC controllers and machine tools. The enhancements in machine tools however have not been integrated under a common platform to support computer aided design (CAD)/computer aided manufacturing (CAM)/CNC software interoperability and as a result a plethora of standards are being used for these systems. ISO 10303 (STEP) and ISO 14649 (STEP-NC) seek to eliminate the barriers in the exchange of information in the CNC manufacturing chain and enable interoperability throughout the manufacturing software domain. With the progress on standardization and implementation, computer systems in the manufacturing process chain require evolution to support the STEP-compliant planning and manufacture. The current paper introduces a novel software platform entitled the Integrated Platform for Process Planning and Control (IP3AC) to support STEP-NC compliant process planning (computer aided process planning (CAPP)/CAM). A prototype process planning system (PPS) based on the platform is then presented as a sample application in the light of future interoperable planning and manufacture. The PPS has been developed with the application of a two-stage strategy for STEP-NC part program generation, namely general workplan generation and specific workplan generation. The work is verified through the use of case study components.

In the domain of manufacturing, computer numerically controllers (CNC) technology is a major contributor to the production capacity of the enterprises. The advances in CNC technology coupled with enhancements in computing systems have provided the basis to re-examine the way in which computer-aided systems (CAx) can be used to enable global manufacturing. Interoperability of the various components of the CAx chain is therefore a major prerequisite for manufacturing enterprises for becoming strategically agile and consequently globally competitive. Being interoperable, resources can be utilized interchangeably in a plug-and-produce manner. Over the last 8 years the eminence of a STEP standard for machining entitled STEP-NC (numerical control) has become a well-known vehicle for research to improve the level of information availability at the CNC machine tool. In this paper, the authors introduce the background to the evolution of CNC manufacturing over the last 50 years and the current standards available for programming. A review of the literature in interoperable CNC manufacturing is then provided relating to milling, turn-mill and other NC processes. The major part of the paper provides a strategic view of how interoperability can be implemented across the CAx chain with a range of standards used to regulate the flow of information. Finally, the paper outlines the advantages and major issues for future developments in interoperability, identifying future key requirements and limiting factors.

With the progress on STEP-NC standardization and implementation, STEP-NC-oriented computer systems in the process chain require evolution to support the STEP-compliant planning and manufacture. This paper explores process planning (CAPP/CAM) based on STEP-NC and presents a CAPP prototype system (PPS) in the light of future interoperable planning and manufacture. The PPS has been developed using STEP-NC features throughout the planning process and applies a two-stage strategy for STEP-NC part program generation, namely general workplan generation and specific workplan generation. The work is verified through use of case study components.