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排序方式: 共有138条查询结果,搜索用时 156 毫秒
1.
A study on helical surface generated by the primary peripheral surfaces of ring tool 总被引:1,自引:1,他引:0
S. Berbinschi V. Teodor N. Oancea 《The International Journal of Advanced Manufacturing Technology》2012,61(1-4):15-24
Often in the engineering practice, cutting tools bounded by primary peripheral surfaces of revolution are used because of their effectiveness. Among these, ring and tangential tools can be used for the generation of constant pitch cylindrical helical surfaces. In this paper, we present an algorithm for the profiling of these types of tools. The algorithm is based on the topological representation of the tool’s primary peripheral surface. The main goal is to devise a methodology for the profiling of tools whose surfaces are reciprocally enveloping with cylindrical helical surfaces. We present a numerical example for the numerical determination of the axial section form for this type of tools. The application method for this algorithm was developed in the CATIA graphical design environment within which the procedure is developed as a vertical application. In addition, we present a solution for the shape correction of the tool’s axial cross-section by considering the existence of singular points on the profile of the helical surface to be generated where multiple normals to the surface exist. 相似文献
2.
Dana Petcu Silviu Panica Marc Frîncu Marian Neagul Daniela Zaharie Georgiana Macariu Dorian Gorgan Teodor Ştefănuţ 《Computer Standards & Interfaces》2012,34(6):493-508
Earth observation data processing and storing can be done nowadays only using distributed systems. Experiments dealing with a large amount of data are possible within the timeframe of a lesson and can give trainees the freedom to innovate. Following these trends and ideas, we have built a proof-of-the-concept platform, named GiSHEO, for Earth observation educational tasks. It uses Grid computing technologies to analyze and store remote sensing data, and combines them with eLearning facilities. This paper provides an overview of the GiSHEO's platform architecture and of its technical and innovative solutions. 相似文献
3.
Solar Cells: High Efficiency Cu2ZnSn(S,Se)4 Solar Cells by Applying a Double In2S3/CdS Emitter (Adv. Mater. 44/2014) 下载免费PDF全文
4.
3D graphical method for profiling gear hob tools 总被引:1,自引:1,他引:0
S. Berbinschi V. Teodor N. Oancea 《The International Journal of Advanced Manufacturing Technology》2013,64(1-4):291-304
This paper approaches the issue of profiling gear hob bounded by a cylindrical helical surface with constant pitch, reciprocally enveloping with an ordered surfaces curl. The process kinematics of generation reproduces the 3D gear between the worm and the wheel. This gear has crossing axes and it is used for the profiling of the primary peripheral surface of the gear hub in the intermediary surface method (the common rack-gear of the surfaces curl to be generated and the primary peripheral surface of the gear hob). An algorithm in the CATIA design environment is presented, based onto an original method for the determination of the reference rack-gear form—the rack-gear reciprocally enveloping with the surfaces curl, using the principle of the cylindrical helical motion decomposition in translation and rotation motions. Graphical and analytical profiling examples are presented for the gear hob for generation of a parallel spline shaft and for the generation of a toothed wheel with involute teeth. Solutions for the interference problems, problems due to the singular points onto the profiles, are presented. 相似文献
5.
Marius Barat Dumitru-Bogdan Prelipcean Dragoş Teodor Gavriluţ 《Journal in Computer Virology》2013,9(4):171-178
With the exponential growth of malware in the last 5 years, the number of polymorphic malware increased as well. The aim of this paper is to describe the evolution throughout a year of four major malware families (FakeAlert, Sirefef, ZBot and Vundo). The analysis has been made in terms of polymorphic mechanisms with regards to the polymorphic mechanisms (such as changes in the packer module, changes in the geometry of file, variation of version information from the resource directory or different methods used to modify the icon of one file) which have been used in order to avoid their detection by anti-malware systems. The malware files were collected every week throughout one year’s time. For each family we have recorded the new variants and the updates that were added to the old ones in order to avoid detection. We have managed to examine more than 1,000 new versions of such files. The current article includes an additional study case. The latter focuses on the methods that have been used by the FakeAlert malware family in order to modify their icons. 相似文献
6.
Camelia Agapescu Anca Cojocaru Adina Cotarta Teodor Visan 《Journal of Applied Electrochemistry》2013,43(3):309-321
This article presents a series of preliminary results regarding the electrodeposition of bismuth, tellurium, and bismuth telluride films at 60 °C from ionic liquids, containing a mixture of choline chloride and oxalic acid (ChCl–OxA). Ten millimolar concentration solutions of BiCl3 and TeO2 were used as precursors in this supporting electrolyte. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to demonstrate the deposition processes on Pt and Cu electrodes. Long-time electrolyses (30–120 min) performed at 60 °C with potential control (between ?0.22 and ?0.37 V vs. Ag reference electrode) have resulted in films deposited on copper substrate. Film surfaces were studied by scanning electron microscopy and analyzed by energy dispersive X-ray spectroscopy. The results of this study show that ChCl–OxA ionic liquid may be considered as a promising substitute of aqueous baths for Bi, Te or Bi2Te3 film plating. 相似文献
7.
Modeling and effect of leakages on heat transfer performance of fixed matrix regenerators 总被引:2,自引:0,他引:2
The following undesired leakages are inherent in operation of fixed matrix regenerators: gas pressure leakages due to pressure difference such as leakages through the valves and through cracks in regenerator housing for very high temperature heat recovery, and carryover leakages from the hot gas to cold gas and vice versa. The objective of this paper is to present a methodology for evaluation of the leakages and to determine quantitatively the detrimental influence of pressure leakages on the regenerator heat transfer performance. In this respect, a drop (reduction) in actual regenerator heat transfer effectiveness due to various leakages is presented in the paper. The results clearly suggest that a drop in the effectiveness due to leakages can be significant and depends on the category of leakages. The flow leakages due to the cracks in the regenerator housing have the most impact on reducing the regenerator performance. 相似文献
8.
Teodor Rus 《Computer Languages, Systems and Structures》1987,12(3-4):173-195
The language of universal algebras is used as a model for programming language specification. BNF rules are employed for specifying the signature of the language algebra instead of the context free syntax. The algorithm for program evaluation is inductively defined by the following universal algebraic construction:
- Any function defined on the generators of a free algebra taking values in the carrier of another similar algebra can be uniquely extended to a homomorphism between the two algebras.
Any conventional programming language can be specified by a finite set of BNF rules and its algebra of symbols is generated by a finite set of generator classes. Thus any function defined on the finite set of generators offers an algebraic mechanism for a universal algorithm for source language program evaluation. 相似文献
9.
We study and compare synchronous parallelization strategies for tabu search. We identify the most promising parallelization approaches, and evaluate the impact on performance and solution quality of some important algorithmic design parameters: length of the synchronization steps, number of processors, handling of exchanged information, etc. Parallelization approaches are implemented and compared by using a tabu search algorithm for multicommodity location-allocation problems with balancing requirements. 相似文献
10.
Teodor C. Przymusinski 《Annals of Mathematics and Artificial Intelligence》1994,12(3-4):141-187
We investigate the class ofstationary or partial stable models of normal logic programs. This important class of models includes all (total)stable models, and, moreover, thewell-founded model is always its smallest member. Stationary models have several natural fixed-point definitions and can be equivalently obtained as expansions or extensions of suitable autoepistemic or default theories. By taking a particular subclass of this class of models one can obtain different semantics of logic programs, including the stable semantics and the well-founded semantics. Stationary models can be also naturally extended to the class of all disjunctive logic programs. These features of stationary models designate them as an important class of models with applications reaching far beyond the realm of logic programming.Partially supported by the National Science Foundation grant #IRI-9313061. 相似文献