Precision manufacturing of freeform surfaces requires accurate positioning of workpiece on the machine tool and measurement instrument with high repeatability during the manufacturing cycle. However, the geometric com...
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ISBN:
(纸本)9780956679079
Precision manufacturing of freeform surfaces requires accurate positioning of workpiece on the machine tool and measurement instrument with high repeatability during the manufacturing cycle. However, the geometric complexity of ultra-precision freeform surfaces brings considerable challenges in precisely localizing the workpiece for different processes including the machining process and the measurement process. This paper presents a study of a Fiducial Aided Calibration and Positioning (FACP) method to achieve better accuracy and efficiency in manufacturing of the ultra-precision freeform surfaces. The FACP method makes use of fiducials to purposely design high precision fiducial fixtures to form a Fiducialaided Computer Aided Design (FA-CAD) of the freeform workpiece which not only calibrates the geometric error of the volume of the machine tool where machining is undertaken but also establishes an intrinsic reference datum of the workpiece for precise location on the machine tool and the measuring instrument so as to link the machining and the measurement process for form characterization and compensation of the form errors of the workpiece. Some preliminary experiments are conducted to realize the capability of the method.
Optimizing operational parameters for syngas production of Texaco coal-water slurry gasifier studied in this paper is a complicated nonlinear constrained problem concerning 3 BP(Error Back Propagation) neural networks...
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Optimizing operational parameters for syngas production of Texaco coal-water slurry gasifier studied in this paper is a complicated nonlinear constrained problem concerning 3 BP(Error Back Propagation) neural networks. To solve this model, a new 3-layer cultural evolving algorithm framework which has a population space, a medium space and a belief space is firstly conceived. Standard differential evolution algorithm(DE), genetic algorithm(GA), and particle swarm optimization algorithm(PSO) are embedded in this framework to build 3-layer mixed cultural DE/GA/PSO(3LM-CDE, 3LM-CGA, and 3LM-CPSO) algorithms. The accuracy and efficiency of the proposed hybrid algorithms are firstly tested in 20 benchmark nonlinear constrained functions. Then, the operational optimization model for syngas production in a Texaco coal-water slurry gasifier of a real-world chemical plant is solved effectively. The simulation results are encouraging that the 3-layer cultural algorithm evolving framework suggests ways in which the performance of DE, GA, PSO and other population-based evolutionary algorithms(EAs) can be improved,and the optimal operational parameters based on 3LM-CDE algorithm of the syngas production in the Texaco coalwater slurry gasifier shows outstanding computing results than actual industry use and other algorithms.
In light of the escalating global energy imperatives,mining of challenging-to-access resources,such as steeply inclined extra-thick coal seams(SIEC),has emerged as one of the future trends within the domain of energy ...
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In light of the escalating global energy imperatives,mining of challenging-to-access resources,such as steeply inclined extra-thick coal seams(SIEC),has emerged as one of the future trends within the domain of energy ***,there is a risk of gas and coal spontaneous combustion coupling disasters(GCC)within the goaf of SIEC due to the complex goaf structure engendered by the unique mining methodologies of *** ensure that SIEC is mined safely and efficiently,this study conducts research on the GCC within the goaf of SIEC using field observation,theoretical analysis,and numerical *** results demonstrate that the dip angle,the structural dimensions in terms of width-to-length ratio,and compressive strength of the overlying rock are the key factors contributing to the goaf instability of *** gangue was asymmetrically filled,primarily accumulating within the central and lower portions of the goaf,and the filling height increased proportionally with the advancing caving height,the expansion coefficient,and the thickness of the surrounding rock *** GCC occurs in the goaf of SIEC,with an air-return side range of 41 m and an air-intake side range of 14 m,at the intersection area of the“<”-shaped oxygen concentration distribution(coal spontaneous combustion)and the“>”-shaped gas concentration distribution(gas explosion).The optimal nitrogen flow rate is 1000 m3/h with an injection port situated 25 m away from the working face for the highest nitrogen diffusion efficacy and lowest risk of gas explosion,coal spontaneous combustion,and *** has significant engineering applications for ensuring the safe mining of SIEC threatened by the GCC.
The machining profile will always deviate from the designed profile, due to the finite tool radius of diamond turning tool. This deviation would occur theoretically before the commencement of actual machining process ...
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ISBN:
(纸本)9780956679079
The machining profile will always deviate from the designed profile, due to the finite tool radius of diamond turning tool. This deviation would occur theoretically before the commencement of actual machining process and introduce error in ultra-precision machining. Conventionally, tool path design will try to minimize the form errors which induced by the finite tool radius (FETR) geometrically. However, for optical components, the best geometrical approximation does not always match the best optical approximation. Thus, merely improving the form accuracies might not be an effective mean to attain a designated optical requirement which would be testified by comparing the designed profile with the measured profile. The measurement would be achieved by using a high precision interferometer. The optical lens would be machined again using tools with reduced tool radius, if the machined profile does not satisfy with the requirements. As tools with smaller radii are more vulnerable to tool wear, such tool will cause larger form errors. Thus, the optimisation process to look for an appropriate tool through trial and error is inevitably time-consuming. To this end the impact of FETR should be predicted and a guideline on selecting a suitable tool to machine an optical lens should be developed for saving time. In this paper, a novel selection system of single point diamond tool for ultra-precision machining of optical lens is proposed. By taking into account the FETR, this system will generate simulated machining profiles for different tools from a designed profile and then simulate the optical performance of these machining profiles based on an optical ray-tracing model. With the help of the ray-tracing model, the wave-front aberration of a simulated focal spot would be estimated. The optimal diamond tool would be selected based on two criteria. It must be able to produce a focal spot with an acceptable amount of aberration while the tool radius should be the larger the bet
The world has seen a peak in unconventional gas development in recent years. Based on the practice of unconventional gas field development domestic in China and abroad, it is risky that the reinjection water may conta...
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Abstract This paper is concerned with the stabilization problem of wireless networked control systems with network-induced delays of time-varying Markovian characterization. The effects of the sample rate changing on ...
Abstract This paper is concerned with the stabilization problem of wireless networked control systems with network-induced delays of time-varying Markovian characterization. The effects of the sample rate changing on the network induced delay is the main topic. At first place, the time delay matrices changing stochastically and arbitrarily are considered. A state feedback controller is designed to guarantee the resulting close-loop system stochastically stable. Following that, a bridge is built to give out a uniform work. A numerical example is presented to illustrate the effectiveness and potential of the developed theoretical results.
Multiple vehicle detection and identification techniques have been widely applied to acquire road traffic information depending on various sensors, such as video camera, induction loop and magnetic sensor. Magnetic se...
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Digital imaging technology has been widely used in opto-electronics products and precision metrology. 3D digital imaging technology is indispensable in the testing and measurement of object's shape, profile and an...
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ISBN:
(纸本)9781887706650
Digital imaging technology has been widely used in opto-electronics products and precision metrology. 3D digital imaging technology is indispensable in the testing and measurement of object's shape, profile and angular distances. This paper focuses on the design and manufacture of a compound eye system for 3D imaging. The main objective is to obtain a realistic 3D positional information of an object from a depth information extracting program. Firstly , a compound eye will be designed to collect the light field information of an image. Secondly, a depth information extracting program will be developed to derive the focus of each sub object in the image.
Coated structures are composed of solid shell and cellular infill. This paper presents an efficient heterogeneous coated structure design framework. The global coated structure, graded microstructures (GMs) and their ...
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