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1

Optimum Design of Forging Process Parameters and Preform Shape under Uncertainties  

NASA Astrophysics Data System (ADS)

Forging is a highly complex non-linear process that is vulnerable to various uncertainties, such as variations in billet geometry, die temperature, material properties, workpiece and forging equipment positional errors and process parameters. A combination of these uncertainties could induce heavy manufacturing losses through premature die failure, final part geometric distortion and production risk. Identifying the sources of uncertainties, quantifying and controlling them will reduce risk in the manufacturing environment, which will minimize the overall cost of production. In this paper, various uncertainties that affect forging tool life and preform design are identified, and their cumulative effect on the forging process is evaluated. Since the forging process simulation is computationally intensive, the response surface approach is used to reduce time by establishing a relationship between the system performance and the critical process design parameters. Variability in system performance due to randomness in the parameters is computed by applying Monte Carlo Simulations (MCS) on generated Response Surface Models (RSM). Finally, a Robust Methodology is developed to optimize forging process parameters and preform shape. The developed method is demonstrated by applying it to an axisymmetric H-cross section disk forging to improve the product quality and robustness.

Repalle, Jalaja; Grandhi, Ramana V.

2004-06-01

2

Effects of Forging Process Parameters on Microstructure Evolution of Aluminum Alloy 7050  

SciTech Connect

The objective of this work is to investigate the behavior of microstructure evolution of aluminum alloy 7050 under the condition of different forging process parameters by means of combining materials physical model with finite element code. For the purpose of establishing constitutive equation and physical model of microstructure evolution, the isothermal compression test were performed by machine Gleeble 1500 on the condition of temperatures ranging from 250 deg. C to 450 deg. C and constant strain rates of 0.01s-1, 0.1s-1, 1s-1 and 10s-1. The behaviors of microstructure evolutions of aluminum alloy 7050 under difference process parameters were studied by metallographic observations. The experiment results showed that recrystallization during forming process occurred at the critical strain and the volume fraction of recrystallization changed with the temperature and strain rate. According to the results of isothermal compression test, a constitutive equation and an empirical model of DRX were obtained. A finite element code DEFORM 3D was used to analyze the influence of different forging process parameters on the behavior of microstructure evolution in details. The present model and simulation method can be served as a useful tool to predict and control the properties and shape of aluminum alloy 7050 components during forging.

Yi Youping; Shi Yan; Yang Jihui; Lin Yongcheng [School of Mechanical and Electrical Engineering, Central South University, 410083 Changsha (China)

2007-04-07

3

Optimisation of shape and process parameters in metal forging using genetic algorithms  

Microsoft Academic Search

An approach to optimal design in forging is presented in this paper. The design problem is formulated as an inverse problem incorporating a finite element thermal analysis model and an optimisation technique conducted on the basis of an evolutionary strategy. A rigid viscoplastic flow-type formulation was adopted, valid for both hot and cold processes. In industrial forming processes most of

C. F. Castro; C. A. C. António; L. C. Sousa

2004-01-01

4

Design of forging process variables under uncertainties  

NASA Astrophysics Data System (ADS)

Forging is a complex nonlinear process that is vulnerable to various manufacturing anomalies, such as variations in billet geometry, billet/die temperatures, material properties, and workpiece and forging equipment positional errors. A combination of these uncertainties could induce heavy manufacturing losses through premature die failure, final part geometric distortion, and reduced productivity. Identifying, quantifying, and controlling the uncertainties will reduce variability risk in a manufacturing environment, which will minimize the overall production cost. In this article, various uncertainties that affect the forging process are identified, and their cumulative effect on the forging tool life is evaluated. Because the forging process simulation is time-consuming, a response surface model is used to reduce computation time by establishing a relationship between the process performance and the critical process variables. A robust design methodology is developed by incorporating reliability-based optimization techniques to obtain sound forging components. A case study of an automotive-component forging-process design is presented to demonstrate the applicability of the method.

Repalle, Jalaja; Grandhi, Ramana V.

2005-02-01

5

Impedance analysis of forging process and strategy study on compliance for forging manipulator  

NASA Astrophysics Data System (ADS)

In the field of heavy forging, there are numerous researches on deformation rule in forging process by FEM simulation, however, not many scholars take the equipment constraint and the mutual reaction load between the forging manipulator clamp and the forging blank into account, which will impact on safety of manipulator body and quality of forging blank. This paper presents an impedance model to describe the load and formulates compliance strategies correspondingly to reduce the mutual reaction load for forging manipulator. Firstly, an FEM model of forging process is built. Meanwhile, the clamp of forging manipulator is added to the model as movement constraint and interaction part between the manipulator and the forming process. Secondly, a typical forging process is simulated by changing the movement constraint, and then an impedance model is established to describe the relationship between the load and movement constraint. Finally, two kinds of compliance strategies are formulated according to the impedance model, one is called free compliance, and the other is initiative/passive compliance. The simulation results show that compliance strategies reduce the load amounting to 5 000 kN in z direction between the manipulator clamp and the forging blank obviously, which may lead to serious accidents, such as the capsizing of forging manipulator, the fracture of manipulator clamp, and so on. The proposed research simulates the more real forging process, gets the initiative/passive compliance strategy which is more simple and suitable to the real producing and better for forming a forging process planning and control system in the modern production, and improves the quality and efficiency of heavy forging.

Zhang, Pu; Yao, Zhenqiang; Du, Zhengchun

2013-07-01

6

Effects of processing parameters in P\\/M steel forging on part properties: A review part III analysis methods  

Microsoft Academic Search

In the last decade, powder metallurgy (P\\/M) technology has made marked advances in competitive manufacturing. P\\/M offers design\\u000a opportunities that are not possible with other methods, as well as significant cost savings. The processing parameters, material\\u000a characteristics, individual stages of parts production, deformation and densification mechanics and tooling, and preform design\\u000a influence the properties of the P\\/M part and related

R. Duggirala; R. Shivpuri

1992-01-01

7

Industrial introduction of the modeling of aeronautical forging and foundry process simulation  

NASA Astrophysics Data System (ADS)

Problems encountered in the industrial application of aeronautical forging and foundry process simulation modeling which arise from both the complexity of the processes simulated and the geometries considered are reviewed. It is noted that current three-demensional meshes are useful in modeling complex geometries. Such simulation programs make possible: (1) detailed process analysis; (2) the study of the sensitivity of various fabrication parameters; (3) equipment optimization; and (4) the efficient automation of fabrication. The most advanced modeling integration has been in the industrial production of large axisymmetric forged parts.

Bachelet, Eric; Honnorat, Yves

1988-08-01

8

A novel process for breakdown forging of coarse-grain intermetallic alloys  

Microsoft Academic Search

The objective of the present work was to develop a novel hot forging process for breakdown of high-temperature intermetallic alloys which exhibit dynamic recrystallization during hot working. During typical forging processes in hydraulic processes, be they based on isothermal or conventional approaches, the ram speed (or sometimes the effective strain rate) is held constant during the forging stroke. In the

S. L. Semiatin; P. A. McQuay; V. Seetharaman

1993-01-01

9

Die design for the radial forging process using 3D FEM  

Microsoft Academic Search

Radial forging is an open forging process used for reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes such as rifling the gun barrels. Most of the previous studies conducted on the radial forging process have used axisymmetric models to understand the effects of die shape on deformation. In order

Abbas Ghaei; Mohammad R. Movahhedy

2007-01-01

10

Process modeling and development for three axisymmetric net shape forgings  

SciTech Connect

The results of dynamic material modeling experiments are reported on aluminum alloys 6061 and 7050, and steel alloy 4340. This information was used to accurately describe the variables in the various constitutive equations used in computer modeling programs. A description of the experimental equipment used to deform the specimens and gather data was given. Previously reported work regarding computer modeling of interface friction and the forging process was reviewed. Using dynamic flow models, three different axisymmetric parts were analyzed for their potential for being produced by net shape or near net shape forging processes. Two aluminum alloy parts were recommended as potential candidates while the steel part was not a potential candidate. Recommendations for processing conditions were also given. 18 refs.

El-Gizawy, A.S. (Missouri Univ., Columbia, MO (United States). Dept. of Mechanical Aerospace Engineering)

1992-03-01

11

Process modelings and simulations of heavy castings and forgings  

NASA Astrophysics Data System (ADS)

The Materials Process Modeling Division, IMR, CAS has been promoting for more than 10 years research activities on modeling and experimental studies on heavy castings and forgings. In this report, we highlight some selected achievements and impacts in this area: To satisfy domestic strategic requirements, such as nuclear and hydraulic power, marine projects and high speed rail, we have developed a number of casting and forging technologies, which combine advanced computing simulations, X-ray real time observation techniques and industrial-scaled trial experiments. These technologies have been successfully applied in various industrial areas and yielded a series of scientific and technological breakthroughs and innovation. Important examples of this strategic research include the hot-processing technologies of the Three Gorge water turbine runner, marine crankshaft manufacturers, backup rolls for hot rolling mills and the production of hundreds-ton steel ingot.

Li, Dianzhong; Sun, Mingyue; Wang, Pei; Kang, Xiuhong; Fu, Paixian; Li, Yiyi

2013-05-01

12

Comparison between cold rotary forging and conventional forging  

Microsoft Academic Search

Cold rotary forging is an innovative incremental metal forming process, which is obviously different from the conventional\\u000a forging process in many aspects, such as the metal flow, degree of inhomogeneous deformation of workpiece and force and power\\u000a parameters. In the current work, a 3D elastic-plastic dynamic explicit FE model of cold rotary forging of a cylindrical workpiece\\u000a is developed under

Xinghui Han; Lin Hua

2009-01-01

13

Numerical simulation and experimental study for the die forging process of a high-speed railway brake disc hub  

NASA Astrophysics Data System (ADS)

With the aim of manufacturing a near-net shape forging product of a brake disk hub for the high-speed railway, the die forging process was designed and optimized in this study. Firstly, based on the measured stress-strain curves at different strain rates and the thermal-physical parameters of 40Cr A steel, a finite element model for the forging process of a high-speed railway brake disc hub was established. Then, the temperature, stress and strain fields were studied and analyzed at the pre-forging and the finial-forging stages. Besides, in order to trace the stress and strain evolution, five points at different positions were chosen on the billet, and the comparison of the state conditions was made among these points. The results have demonstrated that the product can be well formed by an elaborately designed three-stage forging process, which may reduce the metal machine allowance and the producing cost effectively. Finally, an industrial trial was made and a machined product with sound quality was obtained.

Sun, Mingyue; Xu, Bin; Zhang, Long; LI, Dianzhong

2013-05-01

14

First Results of Energy Saving at Process Redesign of Die Forging Al-Alloys  

SciTech Connect

The contribution deals with eco-friendly solutions for shortened production chains of forging light alloys. During the die forging operations a remarkable amount of material goes into the flash and later on into chips during finish machining. These low value side products are rich with embedded energy therefore recycling or reprocessing could be very energy saving procedure.In cooperation with a die forging company a shortened reprocessing cycle has been studied starting from re-melting the forging flash and without additional heating to cast preforms for subsequent die forging. As such preforms have not as good formability characteristics as those done from extruded billets the isothermal forging process has been adopted. First results showed that without cracks and other defects the formability is sufficient for a broad spectrum of forgings.To improve the formability a homogenization process of cast preforms has been implemented. As the process started immediately after casting, amount of additional energy for heating was minimized. To reduce voids forging process was redesigned in a way to assure greater hydrostatic pressures in parts during forging. First results were promising therefore research is going towards improving processes without adding significantly more energy as it is needed for casting with homogenization and die forging.

Pepelnjak, Tomaz; Kuzman, Karl [Faculty of Mechanical Engineering, Askerceva 6, SI-1000 Ljubljana (Slovenia); Kokol, Anton [Kovinar-forging company, Kovaska cesta 12, SI-3205 Vitanje (Slovenia)

2011-05-04

15

First Results of Energy Saving at Process Redesign of Die Forging Al-Alloys  

NASA Astrophysics Data System (ADS)

The contribution deals with eco-friendly solutions for shortened production chains of forging light alloys. During the die forging operations a remarkable amount of material goes into the flash and later on into chips during finish machining. These low value side products are rich with embedded energy therefore recycling or reprocessing could be very energy saving procedure. In cooperation with a die forging company a shortened reprocessing cycle has been studied starting from re-melting the forging flash and without additional heating to cast preforms for subsequent die forging. As such preforms have not as good formability characteristics as those done from extruded billets the isothermal forging process has been adopted. First results showed that without cracks and other defects the formability is sufficient for a broad spectrum of forgings. To improve the formability a homogenization process of cast preforms has been implemented. As the process started immediately after casting, amount of additional energy for heating was minimized. To reduce voids forging process was redesigned in a way to assure greater hydrostatic pressures in parts during forging. First results were promising therefore research is going towards improving processes without adding significantly more energy as it is needed for casting with homogenization and die forging.

Pepelnjak, Tomaž; Kuzman, Karl; Kokol, Anton

2011-05-01

16

Process Modelling of IN718 for Free Forging  

SciTech Connect

Ni based alloy IN718 is important material used for engine shafts, turbine disks of gas turbine engines. The grain refining of the IN718 becomes important because of the improvement of reliability. We have developed newly advanced {delta} process to obtain the grain of less than 22.5 {mu} m (ASTM No.8.0) even after solution treatment. Furthermore we have developed the microstructural prediction system of IN718 for the process modelling. In this paper, the advanced {delta} process and it's process modelling in the turbine disk forging were reported. As the result, we could obtain successful fine microstructure less than 22.5 {mu} m after solution treatment in turbine disk.

Yoshida, Hiroaki; Hatta, Takeshi; Hironaka, Tomohisa; Isogawa, Sachihiro [Research and Development Lab., Daido Steel Co., Ltd., 2-30 Daido-cho, Minami-ku, Nagoya (Japan); Sekiguchi, Hideaki [Shibukawa Plant, Daido Steel Co., Ltd., 500 Ishihara, Shibukawa (Japan)

2007-05-17

17

Process modification of bevel gear forging using three-dimensional finite element analysis  

Microsoft Academic Search

Bevel gear forging has several advantages as compared with conventional gear forming by a cutting process. For example, it reduces the material loss, and the production lead-time and also has the advantage in product quality improvement of using plastic material flow in the gear teeth. In general, gear forging has a process sequence including preforming and final forming because of

Y. K Lee; S. R Lee; C. H Lee; D. Y Yang

2001-01-01

18

Study of the effects of die geometry on deformation in the radial forging process  

Microsoft Academic Search

Radial forging is an open forging process used for reducing the diameters of shafts, tubes, stepped shafts and axels, and creating internal profiles for tubes such as rifling of gun barrels. Usually a mandrel is used inside a tubular workpiece to create internal profile and\\/or size the internal diameter, but the process can also be performed without a mandrel when

A. Ghaei; M. R. Movahhedy; A. Karimi Taheri

2005-01-01

19

A novel process for breakdown forging of coarse-grain intermetallic alloys  

SciTech Connect

The objective of the present work was to develop a novel hot forging process for breakdown of high-temperature intermetallic alloys which exhibit dynamic recrystallization during hot working. During typical forging processes in hydraulic processes, be they based on isothermal or conventional approaches, the ram speed (or sometimes the effective strain rate) is held constant during the forging stroke. In the method introduced here, the ram speed is increased substantially during the forging stroke as the material recrystallizes to a finer-grained structure and its hot workability increases. By this means, fracture is avoided, grain size is reduced, and processing time is decreased, thus improving material quality and reducing cost. The material used to develop and demonstrate the novel forging process was the single phase gamma titanium aluminide, Ti-51Al-2Mn.

Semiatin, S.L. (Wright Lab., Wright-Patterson AFB, OH (United States). Materials Directorate); McQuay, P.A. (AFOSR/AOARD, Tokyo (Japan). Asian Office of Aerospace R and D); Seetharaman, V. (UES, Dayton, OH (United States))

1993-11-01

20

Forging Advisor  

SciTech Connect

Many mechanical designs demand components produced to a near net shape condition to minimize subsequent process steps. Rough machining from slab or bar stock can quickly and economically produce simple prismatic or cylindrical shapes. More complex shapes can be produced by laser engineered net shaping (LENS), casting , or forging. But for components that require great strength in mission critical applications, forging may be the best or even the only option. However, designers of these parts may and often do lack the detailed forging process knowledge necessary to understand the impact of process details such as grain flow or parting line placement on both the forging process and the characteristics of the forged part. Economics and scheduling requirements must also be considered. Sometimes the only viable answer to a difficult problem is to re-design the assembly to reduce loading and enable use of other alternatives.

Kerry Barnett

2003-03-01

21

Study of Residual Stresses in the Barrel Processed by the Radial Forging  

Microsoft Academic Search

When the gun fires in rapid firing rate, serious factors such as the high ambient temperatures, thermal transients and corrosive-erosive environment existing at the bore surface limit the barrel life. Therefore, most of the current gunpsilas rifling is produced by the radial forging process of the high-alloy steel. The residual stresses in the forged product directly affect the fatigue strength,

Liu Lili; Fan Lixia

2009-01-01

22

Mesoscale simulation of microstructure evolution during multi-stage hot forging processes  

NASA Astrophysics Data System (ADS)

The paper presents a two-dimensional cellular automaton (CA) approach coupled with a topology deformation technique for quantitative and topographic prediction of the microstructure evolution during multi-stage hot forging processes. The simulation presented in this work was implemented by an in-house developed C++ program. The grain topography, recrystallization fraction and average grain size were also obtained during a four-hit forging process. The simulated results agree well with the experimental data in terms of average grain size, suggesting that the developed CA model is a reliable numerical approach for predicting microstructure evolution for ultra-super-critical rotor steel during multi-stage hot forging processes.

Chen, Fei; Cui, Zhenshan

2012-06-01

23

Proposal to study stem forgings  

SciTech Connect

Reservoir designs consist of two primary features including the stem(s) and the body segment. The stem is either an integral part of the reservoir or is joined at some point in the fabrication sequence. The current interest is in high strength stems for advanced reservoir designs. The processing necessary to achieve these strength levels may result in heavily cold worked microstructures which may not interface well with the stem requirements. For instance, cold worked 316 plate stock has shown decreased hydrogen compatibility when contrasted to the annealed version in laboratory tests. More recently, Precision Forge produced a 100 ksi yield strength, 304L stem forging with a heavily deformed microstructure which also may show decreased compatibility in hydrogen. The proposed forging contract will evaluate the influence of forging parameters on the microstructure and mechanical properties of 304L and 316 stem forgings. A summary of the data available on 304L stem forgings is shown graphically. The yield strength values are shown for each set of forging parameters. Tensile tests and microstructural examination will be conducted to complete the information for 304L and create a similar graph for 316 stem forgings.

Odegard, B.C.

1982-06-25

24

Influence of die variables on cavity press forging loads  

Microsoft Academic Search

Slug, die and process parameters largely determine the load requirements when forging any given part. An earlier report (Balogun 1974) has indicated the effects of flash dimensions on deformation forces during cavity press forging of round mild steel slugs.The current paper discusses the influences of three main die variables—die friction, extrusion ratio and flash land shape on press forging loads.

S. A. BALOGUN

1975-01-01

25

Modeling microstructure evolution in the delta process forging of superalloy IN718 turbine discs  

NASA Astrophysics Data System (ADS)

The microstructure development in the Delta Process (DP) forging of Superalloy IN718 turbine discs were predicted using the combined approach of axisymmetric finite element simulation and modeling for the dynamic recrystallization and grain growth. In order to establish the deformation constitutive equation and dynamic recrystallization models for the DP process of Superalloy IN718, the isothermal compression tests were carried out in the temperature range 950 to 1010 °C and strain rates range 0.001 to0.1s-1. Moreover, the isothermal heat treatment tests after hot deformation were conducted in the temperature range 950 to 1040°C to generate the grain growth model. The experimental results indicated the existence of the ? phase could make the activation energy of deformation increase. Furthermore, the existence of the ? phase could stimulate the occurrence of dynamic recrystallization, and the grain growth was restrained due to the pinning effect of ? phase. The predicted grain size and its distribution in the DP forging of Superalloy IN718 turbine discs were compared with the actual microstructures deformed by the hot die forging. It was found that the forging with uniform fine grains could be obtained by the application of DP process to the forging of the turbine disk, in which the alloy was pre-precipitated ? phase after the baiting in the original process.

Zhang, Haiyan; Zhang, Shihong; Cheng, Ming; Zhao, Zhong

2013-05-01

26

Evaluation of Fracture in a Three Stage Forging Process Using Continuum Damage Mechanics  

NASA Astrophysics Data System (ADS)

In forging process, formability is limited by ductile fracture. In many cases forgeability is determined by the occurrence of ductile fracture and therefore limitations are set by the appearance of surface or internal cracks within regions that are highly strained due to extensive material flow. In this paper, the continuum damage mechanics framework for ductile materials developed by Lemaitre has been utilized numerically. A constitutive elastic-plastic-damage model has been implemented inside the finite element code ABAQUS. In forming process, crack closure effects have a strong influence on damage evolution. Therefore, it is necessary to split the tensile and compression stresses in damage evolution and deal with them separately. A modified version of Lemaitre model has been implemented and utilized through the study. The prediction of the surface cracks in forging is analyzed numerically. The results could correctly predict the location of surface cracks in the forging process.

Mashayekhi, M.; Ziaei-Rad, S.; Parvizian, J.; Hadavinia, H.

2007-05-01

27

Computer-assisted Rheo-forging Processing of A356 Aluminum Alloys  

Microsoft Academic Search

Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the

H. H. Kim; C. G. Kang

2010-01-01

28

Forging and stamping nonferrous metals. Handbook  

SciTech Connect

Information on the chemical composition, the physical and mechanical properties, the thermomechanical parameters, and the processes of forging and stamping nonferrous metals is given. Aluminum, magnesium and titanium are among the metals discussed.

Korneyev, N.I.; Arzhakov, V.M.; Barmashenko, B.G.; Yemelyanov, V.B.; Kleymenov, V.Y.

1984-05-01

29

Evaluation of Fracture in a Three Stage Forging Process Using Continuum Damage Mechanics  

Microsoft Academic Search

In forging process, formability is limited by ductile fracture. In many cases forgeability is determined by the occurrence of ductile fracture and therefore limitations are set by the appearance of surface or internal cracks within regions that are highly strained due to extensive material flow. In this paper, the continuum damage mechanics framework for ductile materials developed by Lemaitre has

M. Mashayekhi; S. Ziaei-Rad; J. Parvizian; H. Hadavinia

2007-01-01

30

Vacuum-assisted rheo-forging process of A356 aluminum alloys  

Microsoft Academic Search

In recent years, various rheo-forming methods have been developed to produce products with improved mechanical properties. To this end, rheo-forging of metal offers not only superior mechanical strength but also requires much lower machine loads than solid forming processes. However, there are many problems, such as air indraft during the stirring of the molten metal as well as the expense

H. H. Kim; C. G. Kang

2008-01-01

31

Process Development of Large, Close Tolerance Forgings of Nickel Base Superalloys.  

National Technical Information Service (NTIS)

The accomplishments of Phase I of the subject program covering the period July 1, 1965 through Oct. 30, 1966 are detailed in this report. All necessary die blocks have been obtained, machined to contour and used for the forge process. Rene'41 and Udimet 7...

W. H. Couts R. E. Sjoblad

1966-01-01

32

Semisolid die forging process, microstructures and properties of AZ31 magnesium alloy mobile telephone shells  

NASA Astrophysics Data System (ADS)

A semisolid slurry of AZ31 magnesium alloy was prepared by vibrating wavelike sloping plate process, and the semisolid die forging process, microstructures, and properties of the magnesium alloy mobile telephone shell were investigated. The semisolid forging process was performed on a YA32-315 four-column universal hydraulic press. The microstructures were observed by optical microscopy, the hardness was analyzed with a model 450SVD Vickers hardometer, the mechanical properties was measured with a CMT5105 tensile test machine, and the fractograph of elongated specimens was observed by scanning electron microscopy (SEM). The results reveal that with the increase of die forging force, the microstructures of the product become fine and dense. A lower preheating temperature and a longer dwell time are favorable to the formation of fine and dense microstructures. The optimum process conditions of preparing mobile telephone shells with excellent surface quality and microstructures are a die forging force of 2000 kN, a die preheating temperature of 250°C, and a dwell time of 240 s. After solution treatment at 430°C and aging at 220°C for 8 h, the Vickers hardness is 61.7 and the ultimate tensile strength of the product is 193 MPa. Tensile fractographs show the mixing mechanisms of quasi-cleavage fracture and ductile fracture.

Guan, Ren-Guo; Chen, Li-Qing; Cao, Fu-Rong; Zhao, Zhan-Yong; Ren, Yong

2011-12-01

33

Preform design optimization for forging process based on the topological approach  

NASA Astrophysics Data System (ADS)

Preform design plays an important role in forging design especially for parts with complex shapes. In this paper, an attempt was made to develop a topological approach in the preform design of bulk metal forming processes based on the Bi-direction evolutionary structural optimization (BESO) strategy. In this approach, a new element addition and removal criteria based on the equivalent strain have been proposed for evaluating and optimizing the material flow in the forging process. To obtain a smooth preform boundary, a closed B-spline curve based on the least square approximation algorithm is employed to approximate the uneven surface of updated preform. An inhouse developed CNo. program has been employed to integrate the FE simluation, shape optimsation and surface approximation process. A 2D blade forging perform design problem are evaluate using the developed method. The results suggest that the optimized preform has shown better performance in improving the material flow and deformation uniformity during the forging. The results also demonstrate the robustness and efficiency of the developed preform design optimization method.

Shao, Yong; Lu, Bin; Ou, Hengan; Cui, Zhenshan

2013-05-01

34

Process modeling and development for three axisymmetric net shape forgings. Progress report 5  

SciTech Connect

The results of dynamic material modeling experiments are reported on aluminum alloys 6061 and 7050, and steel alloy 4340. This information was used to accurately describe the variables in the various constitutive equations used in computer modeling programs. A description of the experimental equipment used to deform the specimens and gather data was given. Previously reported work regarding computer modeling of interface friction and the forging process was reviewed. Using dynamic flow models, three different axisymmetric parts were analyzed for their potential for being produced by net shape or near net shape forging processes. Two aluminum alloy parts were recommended as potential candidates while the steel part was not a potential candidate. Recommendations for processing conditions were also given. 18 refs.

El-Gizawy, A.S. [Missouri Univ., Columbia, MO (United States). Dept. of Mechanical & Aerospace Engineering

1992-03-01

35

Computer-assisted Rheo-forging Processing of A356 Aluminum Alloys  

SciTech Connect

Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of A356 aluminum molten state. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D V6.1. Samples of metal parts were subsequently fabricated by using hydraulic press machinery. In order to compare the influence of loading method, two types of samples were fabricated: (1) samples fabricated under direct loading die sets (2) those fabricated under indirect loading die sets. The formability and defects, which were predicted by FEM simulation, were similar to those of samples used in practice.

Kim, H. H. [Department of Mechanical and Precision Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Kang, C. G. [School of Mechanical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

2010-06-15

36

Manufacturing of Precision Forgings by Radial Forging  

SciTech Connect

Radial forging is a multi purpose incremental forging process using four tools on the same plane. It is widely used for the forming of tool steels, super alloys as well as titanium- and refractory metals. The range of application goes from reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes in Near-Net-Shape and Net-Shape quality. Based on actual development of a weight optimized transmission input shaft, the specific features of radial forging technology is demonstrated. Also a Finite Element Model for the simulation of the process is shown which leads to reduced pre-processing effort and reduced computing time compared to other published simulation methods for radial forging. The finite element model can be applied to quantify the effects of different forging strategies.

Wallner, S.; Harrer, O.; Buchmayr, B. [Chair of Metal Forming, Department Product Engineering, University of Leoben, Franz Josef Strasse 18, 8700 Leoben (Austria); Hofer, F. [GFM GmbH, Ennser Strasse 14, 4403 Steyr (Austria)

2011-01-17

37

Manufacturing of Precision Forgings by Radial Forging  

NASA Astrophysics Data System (ADS)

Radial forging is a multi purpose incremental forging process using four tools on the same plane. It is widely used for the forming of tool steels, super alloys as well as titanium- and refractory metals. The range of application goes from reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes in Near-Net-Shape and Net-Shape quality. Based on actual development of a weight optimized transmission input shaft, the specific features of radial forging technology is demonstrated. Also a Finite Element Model for the simulation of the process is shown which leads to reduced pre-processing effort and reduced computing time compared to other published simulation methods for radial forging. The finite element model can be applied to quantify the effects of different forging strategies.

Wallner, S.; Harrer, O.; Buchmayr, B.; Hofer, F.

2011-01-01

38

A filling analysis of the forging process of semi-solid aluminum materials considering solidification phenomena  

Microsoft Academic Search

A new forming technology has been developed to fabricate near-net shape products using light metal. Semi-solid forming technology has some advantages compared with conventional forming processes such as die casting, squeeze casting and hot\\/cold forging. In this study, the numerical analysis of semi-solid filling is carried out and corresponding experiments are undertaken for semi-solid materials (SSM) of solid fraction fS=30%

C. G Kang; J. S Choi; D. W Kang

1998-01-01

39

Experimentally valided approach for the simulation of the forging process using mechanical vibration  

Microsoft Academic Search

In this study, an experimental setup of a forging process has been designed which allows to apply vibrations to the lower\\u000a die of amplitude ranging from 0 to 80?µm at frequencies varying from 1 to 130 Hz thanks to the use of a stack piezoelectric\\u000a actuator fed by an electronic inverter. In order to explore those results, a coupling model has

Rith Ly; Christophe Giraud-Audine; Gabriel Abba; Régis Bigot

2009-01-01

40

A simplified pseudo inverse approach for damage modeling in the cold forging process  

NASA Astrophysics Data System (ADS)

This paper presents a simplified numerical method called "Pseudo Inverse Approach" (PIA) for damage prediction in metal forging process modeling and optimization. The approach is based on the knowledge of the final part shape. Some intermediate configurations are introduced and corrected by using a free surface method to consider the deformation paths. Based on the equivalent stress notion and tensile curve, a robust direct algorithm of plasticity is formulated and implemented. The plasticity is coupled with the ductile damage by using a strain based ductile damage model. The forging results obtained by the PIA are compared to those obtained by an incremental approach to show the efficiency and accuracy of the PIA, as well as the abilities to make the damage prediction.

Halouani, A.; Li, Y. M.; Abbès, B.; Guo, Y. Q.

2013-05-01

41

Finite element modelling of forging and other metal forming processes  

Microsoft Academic Search

The fundamental mechanical formulation is recalled for simulation of metal forming processes. The basic principles of 3-dimensional\\u000a finite element discretization and of time integration are summarized. Several important numerical developments for efficient\\u000a computation of large plastic deformation are briefly described. Various fields of applications to real processes are reviewed.\\u000a Illustrative examples are mentioned to show the utilization of the commercial

J.-L. Chenot; L. Fourment; R. Ducloux; E. Wey

2010-01-01

42

On the Dynamics of High-Speed Drop Forging Process.  

National Technical Information Service (NTIS)

Theoretical and experimental studies have been made of the dynamics of a high-speed forming process depending on the rate, temperature, degree of reduction, and type of metal. AV aluminum-alloy bars 50 mm in diameter and 75 mm high were tested by a high-s...

V. P. Chernichenko L. G. Grishin V. N. Yachmeneva

1967-01-01

43

Application of CAE in cold forging and heat treatment processes for manufacturing of precision helical gear part  

Microsoft Academic Search

In this study, numerical simulations, using the general-purpose process simulation software DEFORM-3D\\/HT, were carried out for the design of the cold forged precision helical gear used for the automotive steering part. The helical gear forging was carried out using the designed die set. From the simulation results, forming load, normal pressure, effective strain distributions on the workpiece, and stress distributions

Soo-Young Kim; Satoshi Kubota; Masahito Yamanaka

2008-01-01

44

Changes in magnetic parameters of neutron irradiated SA 508 Cl. 3 reactor pressure vessel forging and weld surveillance specimens  

NASA Astrophysics Data System (ADS)

Irradiation-induced changes in the magnetic parameters and mechanical properties were measured and compared to explore possible correlations for reactor pressure vessel (RPV) forging and weld surveillance Charpy specimens which were irradiated to the neutron fluence of 2.3×1019 n/cm2 (E>1.0 MeV) in a typical pressurized water reactor environment at 290 °C. For mechanical property parameters, Vickers microhardness, tensile and Charpy impact tests were performed and saturation magnetization (Ms), remanence (Mr), coercivity (Hc), and Barkhausen noise amplitude (BNA) were measured for magnetic parameters for both unirradiated and irradiated specimens, respectively. Results of mechanical property measurements showed an increase in yield and tensile strength, Vickers microhardness, 30 ft. lb indexed RTNDT and a decrease in Charpy upper-shelf energy irrespective of forging and weld metals. Hysteresis loops appeared to turn clockwise, resulting in an increase in Hc, and BNA appeared to decrease after irradiation. Both magnetic parameters showed viable correlations to the changes in mechanical parameters (Vickers microhardness, Charpy upper shelf energy) due to irradiation. Even limited, the present study seems to show additional possibilities for the application of this magnetic method in monitoring the mechanical parameter changes due to neutron irradiation.

Chi, Se-Hwan; Chang, Kee-Ok; Hong, Jun-Hwa; Kuk, Il-Hiun; Kim, Chong-Oh

1999-04-01

45

A Combined Radial Forging-Forward Extrusion Forming Process of Alternator Poles  

NASA Astrophysics Data System (ADS)

A combined radial forging-forward extrusion forming process of alternator poles is proposed based on an analysis of the structure of alternator poles as well as the forming die sets. First, a thick-bottom base of the alternator poles is obtained through radial forging. The middle boss and claw teeth are then formed through forward extrusion. A 3D coupled thermomechanical finite element model is employed. Billet deformation, metal flow, and forming load are obtained. The results show that the middle boss cavity is filled earlier and the process is no longer simultaneous extrusion during the second forming step. Then, the forming load increases sharply. An improved process that controls the metal flow in the middle boss cavity and aids in pushing the metal into the corners of the claw teeth cavity is proposed. The middle boss and claw teeth cavities can be filled simultaneously. The sharp increase of the forming load in the final forming stage is avoided. Simulative and experimental results show that the improved process can considerably reduce the final forming load to form a well-shaped product.

Yang, Cheng; Zhao, Shengdun; Zhang, Jianjun

2013-10-01

46

Processing and development of aluminum-silicon powder metallurgy alloys for hot forging technologies  

NASA Astrophysics Data System (ADS)

The growing field of aluminum powder metallurgy (PM) brings promise to an economical and environmental demand for the production of high strength, light weight aluminum engine components. To tackle the limited selection of readily available light alloy blends, an experimental hypoeutectic AlSi alloy was chosen for study. The optimal processing route for this alloy was determined and the mechanical properties were examined. In an effort to further enhance the mechanical properties of the alloys, post sinter forging was investigated. This body of work consists of an introduction to relevant topics in PM, aluminum alloys, and forging followed by three sections of results and discussion. Each represents an accepted or submitted Journal Manuscript intended for journal publication. These sections deliver detailed experimental procedures, results and discussion for the development of the experimental PM alloy Al-65i, a comparison of hot deformation behaviours of Al-65i and Alumix-231 Al5i PM alloys, and their mechanical properties observed upon hot densification. A final section was added to summarize the important findings from each experiment. In the development of Al-65i, the alloy was able to achieve a high sintered density approaching 98%, and a yield strength of 232 MPa in the T6 condition. Upon hot upset forging, the experimental alloy achieved an average density of 99.6% (+/- 0.2%) while the commercial alloy (Alumix-231) achieved 98.3% (+/- 0.6%) of its theoretical density. It was found that the experimentally obtained peak flow stresses for each material studied could be very closely approximated using the semi-empirical Zener-Hollomon models. Upon hot densification it was found that all the mechanical properties of the Al-65i alloy were significantly enhanced. However, due to the fracturing of 5i particles during deformation, Alumix-231 experienced a reduction in density and UT5, while making improvements in ductility.

Mosher, Winston G. E.

47

Comparative study of forging parameters on microstructures and properties between Aluminum alloys Al6063 and Al7075  

Microsoft Academic Search

This research were designed and created hot forging moulds of Aluminum alloys to investigate the effect of heating influence on machine qualifications of Aluminum alloys and know the suitable conditions of hot forging. The experimental variable was forging temperature and analyzed the experiment results for determined the suitable condition in hot forging on two types Aluminum alloysAlSi1Mg:Al6063 and AlZn5.5MgCuAl7075. The

S. SOPHA; S. NANSAARNG

2007-01-01

48

Development of Replacements for Phoscoating Used in Forging, Extrusion and Metal Forming Processes  

SciTech Connect

Many forging, extrusion, heading and other metal forming processes use graphite-based lubricants, phosphate coatings, and other potentially hazardous or harmful substances to improve the tribology of the metal forming process. The application of phosphate-based coatings has long been studied to determine if other synthetic ''clean'' lubricants could provide the same degree of protection afforded by phoscoatings and its formulations. So far, none meets the cost and performance objectives provided by phoscoatings as a general aid to the metal forming industry. In as much as phoscoatings and graphite have replaced lead-based lubricants, the metal forming industry has had previous experience with a legislated requirement to change processes. However, without a proactive approach to phoscoating replacement, many metal forming processes could find themselves without a cost effective tribology material necessary for the metal forming process

Kerry Barnett

2003-03-01

49

Advanced numerical models for the thermo-mechanical-metallurgical analysis in hot forging processes  

NASA Astrophysics Data System (ADS)

In the paper a literature review of the numerical modeling of thermo-mechanical-metallurgical evolutions of a metal in hot forging operations is presented. In particular models of multiaxial loading tests are considered for carbon steels. The collected examples from literature regard phases transformations, also martensitic transformations, morphologies evolutions and transformation plasticity phenomena. The purpose of the tests is to show the correlation between the mechanical and the metallurgical behavior of a carbon steel during a combination of several types of loads. In particular a few mechanical tests with heat treatment are analyzed. Furthermore, Ti-6Al-4V titanium alloy is considered. Such material is a multi-phasic alloy, at room temperature made of two main different phases, namely Alpha and Beta, which evolve during both cooling and heating stages. Several numerical applications, conducted using a commercial implicit lagrangian FEM code are presented too. This code can conduct tri-coupled thermo-mechanical-metallurgical simulations of forming processes. The numerical model has been used to carry out a 3D simulation of a forging process of a complex shape part. The model is able to take into account the effects of all the phenomena resulting from the coupling of thermal, mechanical and metallurgical events. As simulation results strongly depend on the accuracy of input data, physical simulation experiments on real-material samples are carried out to characterize material behavior during phase transformation.

Ducato, Antonino; Fratini, Livan; Micari, Fabrizio

2013-05-01

50

Liquid State Forging: Novel Potentiality to Produce High Performance Components, Process, Plant and Tooling  

NASA Astrophysics Data System (ADS)

The paper deals about a new patented process able to the production of high resistance and high toughness parts, taking into consideration also the tooling need. The molten alloy is introduced into the die cavity at low pressure, then the alloy is forged. The forging action takes place during the alloy solidification process, favouring the reduction of the duration of the process and the production of parts characterised by very high mechanical and ductility properties. The very high mechanical characteristics of the produced parts are obtained thank to their very low porosity content, as well as to their unique microstructure features. Moreover, the process allow the optimisation of the yield of the alloy, in fact the feeding system and the risers are practically absent, this means minimum production of scraps to be recycled. After a short description of the main features of the equipment and of the process, the work take into consideration the aluminium based produced parts, in their as cast state and after T6 heat treatment, comparing their characteristics with those obtainable by the most traditional low pressure and gravity casting processes. In particular, samples for the evaluation of the mechanical properties have been machined from the produced parts to obtain their tensile strength, together with their ductility characteristics. The maximum attained hardness values have also been evaluated. Tensile strength higher than 440 MPa, with elongation up to 18% with hardness higher than 125 HB are easily attainable on Al alloys type A356. Light microscopy observations performed on the transverse section of polished samples and the analysis of the fracture surfaces after mechanical tests allowed to focus the attention on the microstructure details and to highlight the ductile aspects of the fracture to confirm the high quality and high performance of the produced parts.

Rosso, M.; Zago, A.; Claus, P.; Motoiu, P.

2007-04-01

51

Influence of minimum quantity lubrication parameters on tool wear and surface roughness in milling of forged steel  

NASA Astrophysics Data System (ADS)

The minimum quantity of lubrication (MQL) technique is becoming increasingly more popular due to the safety of environment. Moreover, MQL technique not only leads to economical benefits by way of saving lubricant costs but also presents better machinability. However, the effect of MQL parameters on machining is still not clear, which needs to be overcome. In this paper, the effect of different modes of lubrication, i.e., conventional way using flushing, dry cutting and using the minimum quantity lubrication (MQL) technique on the machinability in end milling of a forged steel (50CrMnMo), is investigated. The influence of MQL parameters on tool wear and surface roughness is also discussed. MQL parameters include nozzle direction in relation to feed direction, nozzle elevation angle, distance from the nozzle tip to the cutting zone, lubricant flow rate and air pressure. The investigation results show that MQL technique lowers the tool wear and surface roughness values compared with that of conventional flood cutting fluid supply and dry cutting conditions. Based on the investigations of chip morphology and color, MQL technique reduces the cutting temperature to some extent. The relative nozzle-feed position at 120°, the angle elevation of 60° and distance from nozzle tip to cutting zone at 20 mm provide the prolonged tool life and reduced surface roughness values. This fact is due to the oil mists can penetrate in the inner zones of the tool edges in a very efficient way. Improvement in tool life and surface finish could be achieved utilizing higher oil flow rate and higher compressed air pressure. Moreover, oil flow rate increased from 43.8 mL/h to 58.4 mL/h leads to a small decrease of flank wear, but it is not very significant. The results obtained in this paper can be used to determine optimal conditions for milling of forged steel under MQL conditions.

Yan, Lutao; Yuan, Songmei; Liu, Qiang

2012-05-01

52

Forging; Heat Treating and Testing; Technically Oriented Industrial Materials and Process 1: 5898.05.  

ERIC Educational Resources Information Center

|The course provides students with advanced and exploratory experience in the area of plastic deformation of metals and in the changing of the physical characteristics of metals by the controlled application and timed removal of heat. Course content includes goals, specific objectives, safety in forge work, forging tools and equipment, industrial…

Dade County Public Schools, Miami, FL.

53

The effect of deformation rate on JBK-75 stainless steel forgings  

Microsoft Academic Search

A parametric study was conducted to evaluate the effect of forging rate and forging temperature on the strength and microstructure of a precipitation-hardened, austenitic stainless steel forging. High and low forging rates were achieved using a high energy rate forging (HERF) process and a low velocity mechanical press (MP) respectively. The forging geometry required a two-stage forging sequence. The first

Odegard

1987-01-01

54

Measurement system for hot heavy forgings and its calibration  

NASA Astrophysics Data System (ADS)

Dimensional measurement of hot heavy forgings is desirable to permit real-time process control, but usually is inconvenient because of the difficulty in working with very hot workpieces. This paper presents an approach based on Two-dimensional Laser Range Sensor (TLRS). Firstly, the measurement system can be obtained by assembling TLRS, an axis of rotation, and a servo motor, which rotates and scans forgings in different planes. Then, the coordinates of points of forging's surface can be obtained in coordinate system in scanning plane. Secondly, the origin of Measurement Coordinate System (MCS) at the centre of rotation of TLRS can be located. According to the transformation between Sensor Coordinate System (SCS) and MCS, coordinates of points in different SCS can be transferred into the fixed MCS. Next, the final points of forging's surface in MCS can be obtained. Hence models of hot heavy forgings can be reconstructed by using Triangulated Irregular Network and optimized by employing Delaunay rules. Finally, different parameters of forgings, such as lengths and diameters, can be measured. In order to calibrate the measurement system, a pyramid is proposed to compute the transformation matrix between SCS and MCS based on the projective geometry theory. The new method has been verified by experiments in both the laboratory and the forging workshop. The experimental results indicate that it is much more practical for the real time on-site measurement of hot heavy forgings. This research lays a desirable foundation for the further work.

Du, Yueyang; Du, Zhengchun

2011-05-01

55

Press Forging of Magnesium-Alloy Notebook Case with Complex Geometry  

Microsoft Academic Search

Press forging is a process for forming bosses with thin sheet metals. In this work, press forging has been applied to manufacture magnesium-alloy notebook computer case with complex geometry, such as sidewalls, bosses, and hooks. Forming characteristics, influence of process parameters on metal flow, and forming defect are investigated by using both experimental approach and the finite element method (FEM).

Cheng Sun; Shi-hong Zhang; Wei-dong Tang; Zhong-tang Wang

2010-01-01

56

Industrial Process Design for Manufacturing Inconel 718 Extremely Large Forged Rings  

NASA Astrophysics Data System (ADS)

Inconel 718 is a Ni-Fe-based superalloy that has been central to the gas turbine industry since its discovery in 1963. While much more difficult to process than carbon or stainless steels, among its superalloy peers Inconel 718 has relatively high forgeability and has been used to make discs, rings, shells, and structural components. A metal forming process design algorithm is presented to incorporate key criteria relevant to superalloy processing. This algorithm was applied to conceptual forging and heat treating extremely large rings of Inconel 718 of diameter 1956 mm (77in) and weight 3252 kg (7155 lb). A 3-stage standard thermomechanical (TMP) processing was used, where Stage 1 strain varied from 0.1190 to 0.2941, Stage 2 from 0.0208 to 0.0357 and Stage 3 from 0.0440 to 0.0940. This was followed by heat treatment of a solution anneal (954°C/1750°F for 4 hour hold), air cool, then a double aging (718°C/1325°F for 8 hour hold; furnace cool to 621°C/1150°F 56°C/100°F per hr; 18 hour total time for both steps). Preliminary mechanical testing was performed. Average yield strength of 951 MPa/138 ksi (longitudinal) and 979 MPa/142 ksi (axial) was achieved. Tensile strengths were 1276 MPa/185 ksi (longitudinal) and 1255 MPa/182 ksi (axial). Elongations and reduction of areas attained were, respectively, 18 (long) and 25 (axial) and 28 (long) and 27 (axial).

Ambielli, John F.

57

Efficient process design for closure and healing of voids in open die forging of superhigh C-steel shaft  

NASA Astrophysics Data System (ADS)

In this study, simulation and experimental works are carried out to propose the efficient forging process design for manufacturing workroll made of 1.5wt%C high carbon steel. New forging process design is composed of incremental upsetting, diffusion boding and cogging process for efficient void closure and healing. Since the voids lie along the longitudinal direction of the ingot, the ingot is gradually deformed only in its radial direction during incremental upsetting until void closure takes place. After that, the closed voids are healed by diffusion bonding process in order to assign the strong bonding strength to the closed void and to prevent the re-opening of the closed voids during successive incremental upsetting and cogging process. Experimental works are also carried out to validate the proposed forging process design. In addition, the effect of temperature of diffusion bonding on bonding strength of the closed void is investigated. Finally, the analyses on microstructure at the diffusion-bonded interface and mechanical properties by tensile test are carried out as well. It was found out through simulation and experimental works that the quick void closure takes place by incremental upsetting and the closed void is strongly joined by diffusion bonding. It was confirmed that the process design proposed in this study can be applicable to manufacture the super high carbon workroll with microstructurally soundness.

Kang, Seong-Hoon; Lim, Hyung-Cheol; Lee, Howon; Lee, Young-Seon

2013-05-01

58

Processing and properties of superclean ASTM A508 Cl. 4 forgings  

SciTech Connect

Steels with improved resistance to temper embrittlement are now being produced using ``superclean`` steelmaking technology. This technology involves the use of scrap control, proper electric arc furnace and ladle refining furnace practices to produce steel with very low Mn, Si, P, S and other residual impurities such as Sn, As and Sb. This technology has been applied on a production basis to modified ASTM A508 Cl- 4 material intended for high temperature pressure vessel forgings. Processing and properties of this superclean material are reviewed. In addition, the cleanliness and mechanical properties are compared to conventionally melted A508 Cl. 4 material. The ``superclean`` A508 Cl. 4 mod. was found to meet all specification requirements. In addition, the superclean material was found to possess superior upper shelf CVN properties, a lower FATT{sub 50} and NDTT, along with superior microcleanliness compared to conventional material. Finally, the superclean material was found to be immune to temper embrittlement based on the short-term embrittlement treatments examined.

Hinkel, A.V.; Handerhan, K.J. [Ellwood City Forge, PA (United States); Manzo, G.J. [Ellwood Group Inc., PA (United States). Steel Division; Simkins, G.P. [Westinghouse Electric Corp., Pittsburgh, PA (United States)

1988-12-31

59

Application of thermosyphon air-preheater for energy thrift from a furnace in a hot forging process  

Microsoft Academic Search

This research studied the heat transfer of the thermosyphon air-preheater. An empirical model was developed to predict heat\\u000a transfer and applied to compute the thermosyphon air-preheater in a hot brass forging process. The thermosyphon air-preheater\\u000a was designed, constructed and tested under medium temperature operating conditions with inlet hot gases, ranging between 390–440\\u000a °C in terms of using water as the

L. Yodrak; S. Rittidech; N. Poomsa-ad

2011-01-01

60

Tensile strength improvement of an Mg–12Gd–3Y (wt%) alloy processed by hot extrusion and free forging  

Microsoft Academic Search

An Mg–12Gd–3Y (wt%) alloy was prepared by conventional casting method using permanent steel mold. Then this alloy was subjected\\u000a to hot processing, involving hot extrusion and free forging. Tensile strength at room temperature can be improved, with the\\u000a highest ultimate tensile strength (UTS) value of 390.2 MPa achieved by hot extrusion in comparison to that of as-cast alloy.\\u000a Temperature dependence of

Li Lin; Lijia Chen; Zheng Liu

2008-01-01

61

Application of numerical simulation for wear analysis of warm forging die  

Microsoft Academic Search

Warm forging process has better forming precision than hot forging process and has better formability than cold forging. But warm forging die sustains higher temperature and working pressure, the die wear is faster than those of hot forging and cold forging. The purpose of this research is to combine the experimental techniques, wear model and numerical simulation method to predict

R. S Lee; J. L Jou

2003-01-01

62

The effects of processing bath parameters on the quality and performance of zinc phosphate stearate coatings  

Microsoft Academic Search

In cold metal-forging processes, low-friction coatings often provide the main part of the lubrication. In many cases, zinc phosphate stearate (ZPS) coatings are used. Many parameters affect the coatings' quality and performance. In this paper the typical Brinell indentation test is used to answer two industrial requirements: first, to reveal the sensitivity of the coating with regard to the ageing

L Lazzarotto; C Maréchal; L Dubar; A Dubois; J Oudin

1999-01-01

63

New Trends in Forging Technologies  

NASA Astrophysics Data System (ADS)

Limited natural resources increase the demand on highly efficient machinery and transportation means. New energy-saving mobility concepts call for design optimisation through downsizing of components and choice of corrosion resistant materials possessing high strength to density ratios. Component downsizing can be performed either by constructive structural optimisation or by substituting heavy materials with lighter high-strength ones. In this context, forging plays an important role in manufacturing load-optimised structural components. At the Institute of Metal Forming and Metal-Forming Machines (IFUM) various innovative forging technologies have been developed. With regard to structural optimisation, different strategies for localised reinforcement of components were investigated. Locally induced strain hardening by means of cold forging under a superimposed hydrostatic pressure could be realised. In addition, controlled martensitic zones could be created through forming induced phase conversion in metastable austenitic steels. Other research focused on the replacement of heavy steel parts with high-strength nonferrous alloys or hybrid material compounds. Several forging processes of magnesium, aluminium and titanium alloys for different aeronautical and automotive applications were developed. The whole process chain from material characterisation via simulation-based process design to the production of the parts has been considered. The feasibility of forging complex shaped geometries using these alloys was confirmed. In spite of the difficulties encountered due to machine noise and high temperature, acoustic emission (AE) technique has been successfully applied for online monitoring of forging defects. New AE analysis algorithm has been developed, so that different signal patterns due to various events such as product/die cracking or die wear could be detected and classified. Further, the feasibility of the mentioned forging technologies was proven by means of the finite element analysis (FEA). For example, the integrity of forging dies with respect to crack initiation due to thermo-mechanical fatigue as well as the ductile damage of forgings was investigated with the help of cumulative damage models. In this paper some of the mentioned approaches are described.

Behrens, B.-A.; Hagen, T.; Knigge, J.; Elgaly, I.; Hadifi, T.; Bouguecha, A.

2011-05-01

64

Tensile Properties of Ti 6Al-4V Heavy-Section Forgings.  

National Technical Information Service (NTIS)

The standard forged and low temperature standard forged produced the highest strength and ductility parameters regardless of subsequent heat treatment, when compared to beta forged material. Duplex annealing results in the highest annealed strength and du...

M. Raefsky

1968-01-01

65

A knowledge-based engineering design tool for metal forging  

Microsoft Academic Search

This paper describes a knowledge-based design tool enabling the generation of hot forging die designs from a component profile. The system integrates the hot forging die design process into a single framework and guides the user through the design process enabling the generation of forgeable geometry from a component profile taking into account machine, material and forging company specific data,

J. Kulon; D. J. Mynors; P. Broomhead

2006-01-01

66

Application of CAE for hot-forging of automotive components  

Microsoft Academic Search

Since the late 1980s, the commercial based forging analysis software has come into the market and brought some benefits for optimizing forging processes. Nissan Motor Co. has applied CAE (computer-aided engineering) mainly to hot-forging processes. This paper describes three examples of simulations which were applied to our hot-forging plant floor. The first example is a model experiment using Plasticine and

Shinichiro Fujikawa

2000-01-01

67

Dynamic material modeling in hot forging  

Microsoft Academic Search

A dynamic material model that characterized flow behavior in the workpiece under forging conditions was required to optimize the process and produce defect-free product at minimum cost. Constitutive equations describe the relationship between stress, strain rate, and temperature under forging conditions. Using aluminum alloy 7050, numerous deformation experiments were conducted to fully characterize constitutive equation variables. A thorough description of

El-Gizawy

1992-01-01

68

Analysis comparative of different simulation techniques by the finite element method in the study of an open die forging process  

NASA Astrophysics Data System (ADS)

The scope of this work is to study a forging process at room temperature and at macroscopic level. The mechanism of deformation is influenced by the friction and the reduction ratio, but the influence of the geometry of the billet (aspect ratio) needs also to be taken into account. The objective will be to compare the results obtained during a simulation with the code based on Finite Element Method (DEFORM 2D/3D), with those obtained by analytical methods in order to validate the numerical model. Taking into account that deformation is not uniform and the free surface suffers a phenomenon known as barrel-shaped, that is not covered by analytical methods, the data obtained will compared with those obtained with the FEM code ABAQUS. The aim of this comparison between analytical and numerical methods using two commercial codes instead one, is a proposed way to validate a Finite Element simulation when experimental data are not available or do not exist yet.

Olivares, F. J.; Camacho, A. M.; Sebastián, M. A.

2012-04-01

69

Internationalisation of Bharat Forge Limited: a case study  

Microsoft Academic Search

Purpose – The purpose of this paper is to follow the internationalisation of an Indian company, Bharat Forge Limited. It studies how a small company from India becomes one of the leading players in the global forging industry. Design\\/methodology\\/approach – This is a case study approach for studying the process of internationalisation in one particular firm. Findings – Bharat Forge

Rajesh K. Pillania

2008-01-01

70

Cast Titanium Alloy Radial Impellers: A new casting process costs less than conventional forging and machining.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A casting process for the fabrication of Ti-6A1-4V alloy radial-compressor impellers has been developed. Impellers made by the improved process cost less than simila...

1982-01-01

71

The influence of induction heating on the microstructure of A356 for semi-solid forging  

Microsoft Academic Search

Semi-solid forging is a compound forging technology to develop conventional forging process. Among the several steps of the semi-solid forging process, the heating step of the billet prior to semi-solid forging step is necessarily required to obtain a globular microstructure. For the forming operation to work properly, it is important to heat the billet uniformly for the uniformity of solid–liquid

Jae Chan Choi; Hyung Jin Park; Byung Min Kim

1999-01-01

72

Simulation of 7050 Wrought Aluminum Alloy Wheel Die Forging and its Defects Analysis based on DEFORM  

SciTech Connect

Defects such as folding, intercrystalline cracking and flow lines outcrop are very likely to occur in the forging of aluminum alloy. Moreover, it is difficult to achieve the optimal set of process parameters just by trial and error within an industrial environment. In producing 7050 wrought aluminum alloy wheel, a rigid-plastic finite element method (FEM) analysis has been performed to optimize die forging process. Processing parameters were analyzed, focusing on the effects of punch speed, friction factor and temperature. Meanwhile, mechanism as well as the evolution with respect to the defects of the wrought wheel was studied in details. From an analysis of the results, isothermal die forging was proposed for producing 7050 aluminum alloy wheel with good mechanical properties. Finally, verification experiment was carried out on hydropress.

Huang Shiquan; Yi Youping; Zhang Yuxun [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China)

2010-06-15

73

Effect of Various Heat Treatment Processes on Fatigue Behavior of Tool Steel for Cold Forging Die  

NASA Astrophysics Data System (ADS)

Effects of various heat treatment processes, including "Q/T (quenching and tempering)", "Q/CT/T (Quenching, cryogenic treatment and tempering)", "Q/T (quenching and tempering) + Ti-nitriding" and "Q/CT/T (Cryogenic treatment and tempering) + Ti-nitriding", on S-N fatigue behavior of AISI D2 tool steel were investigated. The optical micrographs and Vicker's hardness values at near surface and core area were examined for each specimen. Uniaxial fatigue tests were performed by using an electro-magnetic resonance fatigue testing machine at a frequency of 80 Hz and an R ratio of -1. The overall resistance to fatigue tends to decrease significantly with Ti-nitriding treatment compared to those for the general Q/T and Q/CT/T specimens. The reduced resistance to fatigue with Ti-nitriding is discussed based on the microstructural and fractographic analyses.

Jin, S. U.; Kim, S. S.; Lee, Y. S.; Kwon, Y. N.; Lee, J. H.

74

FORGING BERYLLIUM POWDER  

Microsoft Academic Search

The developments and results obtained in press forging beryllium powder ; are described. The forging method consists of using pressures in the range of ; 20,000 to 100,000 psi, sintering times from l sec to l min, and two temperature ; ranges of l600 and 1900 deg F. The description of a nonberyllium (stainless ; steel) can fabricated for holding

Cieslicki

1962-01-01

75

Estimation of friction under forging conditions by means of the ring-on-disc test  

SciTech Connect

In order to understand the tribological processes and interactions in the tool-workpiece-interface systematically, basic experiments that allow an independent variation of influencing parameters are necessary. The ring-on-disc test is a popular model experiment that is often used in tribological analyses at low normal contact pressures.The scope of the paper is an analysis of the applicability of the ring-on-disc test for high normal pressures as used in forging processes, using aluminium AA6082 as workpiece material. It turned out, that this test is a convenient method to measure friction under forging conditions.

Buchner, Bernhard; Umgeher, Andreas; Buchmayr, Bruno [University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)

2007-04-07

76

Mechanical Testing Development for Reservoir Forgings  

SciTech Connect

The goal of this project was to determine the machining techniques and testing capabilities required for mechanical property evaluation of commercially procured reservoir forgings. Due to the small size of these specific forgings, specialized methods are required to adequately machine and test these sub-miniature samples in accordance with the requirements of ASTM-E8 and ASTM-E9. At the time of project initiation, no capability existed at Federal Manufacturing & Technologies (FM&T) to verify the physical properties of these reservoirs as required on the drawing specifications. The project determined the sample definitions, machining processes, and testing procedures to verify the physical properties of the reservoir forgings; specifically, tensile strength, yield strength, reduction of area, and elongation. In addition, a compression test method was also developed to minimize sample preparation time and provide a more easily machined test sample while maintaining the physical validation of the forging.

Wenski, E.G.

2000-05-22

77

Forging of FeAl intermetallic compounds  

SciTech Connect

Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

Flores, O.; Juarez, J.; Campillo, B.; Martinez, L. [UNAM, Cuernavaca (Mexico). Lab. de Cuernavaca; Schneibel, J.H. [Oak Ridge National Lab., TN (United States)

1994-09-01

78

Heating Methods of Forgings.  

National Technical Information Service (NTIS)

The report deals with a study of the most usual electrical heating methods of forgings. Those are investigated under ''Norwegian'' conditions. Inductive heating systems seem to be expensive and result in small return on investment for small production ser...

T. Stroemsvik

1982-01-01

79

The occurrence of shear bands in nonisothermal, hot forging of Ti6AI2Sn4Zr2Mo0.1Si  

Microsoft Academic Search

The occurrence of shear bands in nonisothermal, hot forging of Ti-6Al-2Sn-4Zr-2Mo-0. ISi (Ti-6242) was investigated in order to establish the material properties and process parameters which generally lead to shear bands and shear cracks in conventional hot forging of metals. Upset compression tests on cylindrical samples and lateral sidepressing tests on long, round bars were performed to determine the modes

S. L. Semiatin; G. D. Lahoti

1983-01-01

80

The occurrence of shear bands in nonisothermal, hot forging of Ti6AI2Sn4Zr2Mo0.1Si  

Microsoft Academic Search

The occurrence of shear bands in nonisothermal, hot forging of Ti-6Al-2Sn-4Zr-2Mo-0. ISi (Ti-6242) was investigated in order\\u000a to establish the material properties and process parameters which generally lead to shear bands and shear cracks in conventional\\u000a hot forging of metals. Upset compression tests on cylindrical samples and lateral sidepressing tests on long, round bars were\\u000a performed to determine the modes

S. L. Semiatin; G. D. Lahoti

1983-01-01

81

Computer-aided die design for axis-symmetric cold forging products by feature elimination  

Microsoft Academic Search

The authors consider forging to be a procedure for adding features to a raw material, and process planning to be the inverse procedure. Each step of the forging process is thought of as a combination of feature eliminating processes. Depending on the above, the authors have developed a CAD system to design forging sequences and die profiles. The system designs

Takahiro Ohashi; Satoshi Imamura; Toru Shimizu; Mitsugu Motomura

2003-01-01

82

31. FORGE, ANVIL, POWER FORGE HAMMER (FRONT TO BACK), AND ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

31. FORGE, ANVIL, POWER FORGE HAMMER (FRONT TO BACK), AND DOORWAY INTO MAIN SHOP-LOOKING SOUTHWEST. - W. A. Young & Sons Foundry & Machine Shop, On Water Street along Monongahela River, Rices Landing, Greene County, PA

83

Establish Manufacturing Methods for Closed Die Aluminum Forgings with Improved Stress Corrosion Resistance.  

National Technical Information Service (NTIS)

To evaluate SCC susceptibility as it relates to forging processing, a 7079 aluminum alloy landing gear outer cylinder was produced using five different forging techniques. Three of these techniques formed the part with a solid barrel using differing preli...

C. A. Morris A. G. Cerrone

1969-01-01

84

Finite element modelling simulation of radial forging of tubes without mandrel  

Microsoft Academic Search

Radial forging is an open forging process used for reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes such as rifling the gun barrels. The radial forging of tubes is usually performed over a mandrel to create an internal profile and\\/or size the internal diameter; but the process can also

A. Ghaei; M. R. Movahhedy; A. Karimi Taheri

2008-01-01

85

Dynamic material modeling in hot forging. Progress report 4  

Microsoft Academic Search

A dynamic material model that characterized flow behavior in the workpiece under forging conditions was required to optimize the process and produce defect-free product at minimum cost. Constitutive equations describe the relationship between stress, strain rate, and temperature under forging conditions. Using aluminum alloy 7050, numerous deformation experiments were conducted to fully characterize constitutive equation variables. A thorough description of

El-Gizawy

1992-01-01

86

NEW FORGE WELDING OF ALUMINUM AND MAGNESIUM ALLOYS  

Microsoft Academic Search

A new forge-welding process for weldng high-strength aluminum and ; magnesium alloys has been developed. This forge welding consists of heating the ; parts to be welded to a temperature which is high enough to allow good uniform ; flow of the materials without cracking and yet the temperature is sufficiently ; low that the samples are not overaged or

L. A. Cook; D. G. Shafer

1958-01-01

87

The effect of deformation rate on JBK-75 stainless steel forgings  

SciTech Connect

A parametric study was conducted to evaluate the effect of forging rate and forging temperature on the strength and microstructure of a precipitation-hardened, austenitic stainless steel forging. High and low forging rates were achieved using a high energy rate forging (HERF) process and a low velocity mechanical press (MP) respectively. The forging geometry required a two-stage forging sequence. The first stage or preform was identical for both forging processes. The final stage used similar die geometries with minor modifications to accommodate the attachment to the respective hammers. The resulting microstructure and mechanical properties were significantly different. These differences are attributed to the effects of strain rate and temperature. 10 figs., 1 tab.

Odegard, B.C.

1987-10-01

88

High Velocity Forging Technology.  

National Technical Information Service (NTIS)

A report is made of a manufacturing methods program to investigate the dynamic response of selected aerospace alloys deformed by upset forging from room temperature to 1950F at impact strain rates from quasi-static (100 in/in/sec.) to 8000 in/in/sec. This...

C. M. Phelan D. W. Truelock G. R. DiGiacomo J. A. Fouse J. R. Russell

1968-01-01

89

Investigations on Forging Dies with Ceramic Inserts by means of Finite-Element-Analysis  

Microsoft Academic Search

The tools in hot forging processes are exposed to high thermal and mechanical loadings. Tempering of the tool edge layer occurs as a result of thermal loadings. This leads to a gradual hardness loss of the tool material and increase of wear over forging cycles. Hence, the tool life in hot forging is mainly limited by wear. An extension of

B.-A. Behrens; F. Schaefer; M. Bistron

2007-01-01

90

Technological study of liquid die forging for the aluminum alloy connecting rod of an air compressor  

Microsoft Academic Search

The aluminum alloy connecting rod of an air compressor was manufactured with liquid die forging replacing die casting and hot die forging. Not only were the defects of gas holes, porosity and non-metal inclusions in the die casting eliminated, but also the investment of the forging equipment and the performing process were decreased, and the coefficient of material utilization and

F. Yin; G. X. Wang; S. Z. Hong; Z. P. Zeng

2003-01-01

91

Grain evolution during hot forging  

NASA Astrophysics Data System (ADS)

A review on grain evolution during hot forging is presented in this paper. The discussion focus is on the experimental law, the microscopic mechanism, the physical model and the evolution equations of grain refinement and growth. This is because the grain evolution is the most important microstructure evolution effecting on the part mechanical behaviors, and to establish reasonable grain evolution is a very important and difficult work for macro microscopic coupling constitutive equation. The following contents about constitutive equation and grain evolution are discussed. 1) The experimental phenomena and evolution laws of grain growth and grain refinement under differential working conditions (deformation, heating, cooling) in order to adapt to the needs of numerical simulation of whole forging process. 2) The advantages and disadvantages of the traditional empirical equations on grain growth, grain refinement and recrystallization process are analyzed. 3) The recent advances in physic models for dynamic recrystallizaton and dynamic grain growth are introduced in detail. Comparing to the empirical equations, these models are closer to the actual physical process. The models not only describe the details of grain changes, but also reveal the relationship between the accumulated dislocations energy and grain size evolution. In addition, the assumptions used in the models and their influences on prediction function are also discussed in order to improve the models.

Jin, Quanlin

2013-05-01

92

A material based approach to creating wear resistant surfaces for hot forging  

NASA Astrophysics Data System (ADS)

Tools and dies used in metal forming are characterized by extremely high temperatures at the interface, high local pressures and large metal to metal sliding. These harsh conditions result in accelerated wear of tooling. Lubrication of tools, done to improve metal flow drastically quenches the surface layers of the tools and compounds the tool failure problem. This phenomenon becomes a serious issue when parts forged at complex and are expected to meet tight tolerances. Unpredictable and hence uncontrolled wear and degradation of tooling result in poor part quality and premature tool failure that result in high scrap, shop downtime, poor efficiency and high cost. The objective of this dissertation is to develop a computer-based methodology for analyzing the requirements hot forging tooling to resist wear and plastic deformation and wear and predicting life cycle of forge tooling. Development of such is a system is complicated by the fact that wear and degradation of tooling is influenced by not only the die material used but also numerous process controls like lubricant, dilution ratio, forging temperature, equipment used, tool geometries among others. Phenomenological models available u1 the literature give us a good thumb rule to selecting materials but do not provide a way to evaluate pits performance in field. Once a material is chosen, there are no proven approaches to create surfaces out of these materials. Coating approaches like PVD and CVD cannot generate thick coatings necessary to withstand the conditions under hot forging. Welding cannot generate complex surfaces without several secondary operations like heat treating and machining. If careful procedures are not followed, welds crack and seldom survive forging loads. There is a strong need for an approach to selectively, reliably and precisely deposit material of choice reliably on an existing surface which exhibit not only good tribological properties but also good adhesion to the substrate. Dissertation outlines development of a new cyclic contact test design to recreate intermittent tempering seen in hot forging. This test has been used to validate the use of tempering parameters in modeling of in-service softening of tool steel surfaces. The dissertation also outlines an industrial case study, conducted at a forging company, to validate the wear model. This dissertation also outlines efforts at Ohio State University, to deposit Nickel Aluminide on AISI H13 substrate, using Laser Engineered Net Shaping (LENS). Dissertation reports results from an array of experiments conducted using LENS 750 machine, at various power levels, table speeds and hatch spacing. Results pertaining to bond quality, surface finish, compositional gradients and hardness are provided. Also, a thermal-based finite element numerical model that was used to simulate the LENS process is presented, along with some demonstrated results.

Babu, Sailesh

93

Modeling and simulation of austenite grain evolution for heavy forging steel 30Cr2Ni4MoV undergoing hot deformation  

NASA Astrophysics Data System (ADS)

30Cr2Ni4MoV is widely used as heavy forging materials for low pressure rotors which equips the ultra-supercritical power generations. The final properties of the heavy forging products relies apparently on the grain size of the material, so that the grain should be refined and homogenized during forming process through controlling the working parameters during forming process. For this purpose, the research on the modeling and simulation of austenite grain evolution is conducted for different forming stages: the grain growth during heating, dynamic recrystallization (DRX) during hitting, and meta-dynamic (MDRX) and static recrystallization (SRX) during hitting intervals. Experiment-based phenomenological models, as easy ways to characterize the grain evolution, are established for the process of heating and single-hit, while the Cellular Automaton simulations are applied for tracing more complex recrystallization process during multi-hit deformations. The research shows that, for heavy forgings, the long-time heating process can cause very coarse grains which are harmful to the final properties. Therefore, in order to refine and homogenize the grain size for the heavy forgings, the working parameters for forging should be determined to ensure the recrystallization can be completed and the deformation can be uniformly distributed. Some applications of the models and simulation method in multi-hit process are also demonstrated.

Cui, Zhenshan; Li, Cuidong; Chen, Fei; Sui, Dashan

2013-05-01

94

Choosing optimal forging conditions in isothermal and hot-die forging  

Microsoft Academic Search

A process-model was developed based on the slab-method to calculate stress distributions and strains. The heat transfer problem\\u000a was analyzed using FEM-methods and simplified by using non-dimensional analysis. The process-model could then be expanded\\u000a with heat transfer calculations between billet and die. Using the model optimal forging condition for hot-die and isothermal\\u000a forging were calculated. The upsetting of a stainless

C. R. Boër; H. Rydstad; G. Schröder

1985-01-01

95

Isothermal Roll Forging of T55 Compressor Blades.  

National Technical Information Service (NTIS)

The objective of this manufacturing technology program was to demonstrate feasibility to produce T55 compressor blades by isothermal roll forging within 0.010 inch of drawing tolerances. This objective was accomplished through process definition and appli...

F. K. Rose A. G. Metcalfe

1977-01-01

96

Transmission electron microscopy studies of thermomechanically control processed multiphase medium-carbon microalloyed steel: Forged, rolled, and low-cycle fatigued microstructures  

Microsoft Academic Search

A ferrite-bainite-martensite (F-B-M) microstructure was produced in a medium-carbon microalloyed (MA) steel through two routes,\\u000a namely, low-temperature finish forging and rolling, followed by a two-step cooling (TSC) and annealing. Transmission electron\\u000a microscopy (TEM) was employed to study the microstructural evolution in control forged and rolled material after TSC followed\\u000a by annealing (TSCA). A TEM investigation was also carried out on

S. Sankaran; Gouthama; S. Sangal; K. A. Padmanabhan

2006-01-01

97

Advanced rotor forgings for high-temperature steam turbines. Volume 1. Ingot and forging production. Final report  

Microsoft Academic Search

Three advanced steel-melting processes - low-sulfur vacuum silicon deoxidation, electroslag remelting, and vacuum carbon deoxidation (VCD) - were applied to produce three CrMoV (ASTM A470, Class 8) steel forgings for steam turbine application. Ingots weighing about 100 t each were produced using these three processes, and rotors were forged with final weights of about 30 t each. Compared to the

V. P. Swaminathan; J. E. Steiner; A. Mitchell

1986-01-01

98

Characterization of deformation stability in hot forging of conventional Ti–6Al–4V using processing maps  

Microsoft Academic Search

The deformation behavior of Ti–6Al–4V alloy under hot compression conditions was characterized in the temperature range 850–1000°C and strain rate range 0.001–10s?1. Processing maps were generated using the dynamic material model (DMM), unifying the relationships between constitutive deformation behavior, hot workability and microstructures evolution. Stable deformation regions were defined by Malas’ stability criteria. The processing maps obtained at different strains

Nho-Kwang Park; Jong-Taek Yeom; Young-Sang Na

2002-01-01

99

Application of the finite-element method to the radial forging of large diameter tubes  

Microsoft Academic Search

Previous investigations of large-diameter tube forging using the radial-forging process have been based on highly simplified slab and upper-bound process models. In order to make accurate predictions of the thermal and mechanical history of the workpiece, more detailed models are required. In this paper, a model of the tube-forging process based on the rigid-thermoviscoplastic finite-element method is considered. The results

Joseph P. Domblesky; Rajiv Shivpuri; Brett Painter

1995-01-01

100

An investigation of the uniformity of mechanical properties of forgings of VT9 titanium alloy after superplastic deformation and high-temperature thermomechanical processing  

Microsoft Academic Search

The results are presented of evaluation of the uniformity of mechanical properties and structure of VT9 alloy after deformation with different degrees under conditions of superplasticity and high-temperature thermomechanical working. It is shown that the strength and plastic properties of forgings of this alloy after superplastic deformation with degrees from I0 to 70% are stable and quite high. The macro-

G. A. Salishchev; R. Ya. Lutfullin; M. A. Murzinova

1991-01-01

101

Influence of thermo-mechanical processing and different post-cooling techniques on structure and properties of an ultra low carbon Cu bearing HSLA forging  

Microsoft Academic Search

An ultra low carbon Cu bearing HSLA steel, micro alloyed with Nb and Ti was forged in two stages and subsequently cooled at different cooling rates. Variation in microstructures and the mechanical properties at different cooling rates have been studied. Volume fraction of bainitic phase has been found to vary with different cooling rates. Maximum strength was achieved in this

A Ghosh; Samar Das; S Chatterjee; B Mishra; P Ramachandra Rao

2003-01-01

102

A numerical simulation of super-plastic die forging process for Zr-based bulk metallic glass spur gear  

Microsoft Academic Search

Because of the high strength and hardness at room temperature, the processing of bulk metallic glasses (BMGs) is very difficult whether by machining or by plastic forming, and the applications of BMGs are restricted. The development of super-plastic precise forming technology, utilizing viscous flowing property of BMGs exhibited in super-cooled liquid region, will lead to wider applications of the alloys.

Zhihao Zhang; Jianxin Xie

2006-01-01

103

Non-isothermal FEM analyses of large-strain back extrusion forging  

Microsoft Academic Search

Back extrusion forging is a complex metal forming operation dominated by large-strain, non-isothermal deformation. NIKE2D, a fully vectorized implicit finite-element program developed at Lawrence Livermore National Laboratory, was applied to a two-stage isothermal back extrusion forging process. Modeling of the forging process required special features in the FEM code such as friction and interactive rezoning that allows for remeshing of

E. C. Flower; J. O. Hallquist; A. B. Shapiro

1986-01-01

104

The complete process of bioresorption and bone replacement using devices made of forged composites of raw hydroxyapatite particles/poly l-lactide (F-u-HA/PLLA).  

PubMed

Here we document the complete process of bioresorption and bone replacement of rods made of forged composites of unsintered hydroxyapatite particles/poly l-lactide (F-u-HA/PLLA) implanted in the femoral medullary cavities of rabbits. Bioresorption, osteoconductive bioactivity and bone replacement were compared in three implantation sites. In the first site, the end of the rod was located near the endosteum in the proximal medullary cavity. In the second, the rod was located at the centre of the bone marrow space without contacting the endosteum. In the third, the rod was in direct contact with cancellous bone within the distal femoral condyle. Micro-computerised tomography, scanning electron microscopy and photomicrographs of stained sections were used to document the complete process of bioresorption and bone replacement. At the first implantation site, the rod was completely resorbed and unbound u-HA particles were detected in and around the endosteum 5-6 years after implantation. At the second site, the rod showed significant shrinkage 4-5 years after implantation due to the release of almost all the PLLA, although a contracted cylindrical structure containing a few u-HA persisted even after approximately 6 years. At the third site, u-HA particles were almost completely replaced with bone after 5-6 years. Conversely, PLLA-only rods showed little bone conduction, and small amounts of degraded PLLA debris and intervening some tissue persisted even after long periods. Namely, the u-HA/PLLA composites were replaced with bone in the distal femoral condyle, where they were in direct contact with the bone and new bone formation was anatomically necessary. By contrast, composite rods were resorbed without replacement in the proximal medullary cavity, in which new bone growth was not required. We therefore conclude that the F-u-HA30/40 composites containing 30 wt%/40 wt% u-HA particles are clinically effective for use in high-strength bioactive, bioresorbable bone-fixation devices with the capacity for total bone replacement. PMID:15860210

Shikinami, Yasuo; Matsusue, Yoshitaka; Nakamura, Takashi

2005-09-01

105

Automatic feature extraction from micrographs of forged superalloys  

NASA Astrophysics Data System (ADS)

The manual determination of metallurgical parameters of forged superalloys can be dramatically improved by automatic, image-processing-based feature extraction. With the proposed methods, the typical errors during grain size estimation for Inconel 718 and Allvac 718Plus ™ , caused by twins and other artifacts like scratches, can be eliminated. Different processing strategies for grain size estimation allow the application of a wide range of ASTM grain size numbers from G3 to G12 with the typical variations in the manifestation of metallurgical details and the magnification-related limitations of image quality. Intercept counting strategies show advantages for samples with pronounced anisotropy and can produce detailed statistics on grain orientation. In addition to a single grain size number, grain size histograms offer a more precise description of the material properties.

Berhuber, E.; Rinnhofer, A.; Stockinger, M.; Benesova, W.; Jakob, G.

2008-07-01

106

Hot shape forging of gas turbine disk using microstructure prediction and finite element analysis  

Microsoft Academic Search

The Waspaloy, a Ni-based superalloy, has been widely used for forging material of gas turbine disk since it requires the high\\u000a tensile strength at high temperature and good resistance to low cycle fatigue. The purpose of this study is to develop a forging\\u000a process of turbine disk that satisfies the hot deformation characteristics of Waspaloy. Generally, the hot forging of

Do-Jin Cha; Dong-Kwon Kim; Jong-Rae Cho; Won-Byong Bae

2011-01-01

107

Microstructure evolution of different loading zones during TA15 alloy multi-cycle isothermal local forging  

Microsoft Academic Search

The microstructure evolution of the TA15 Ti-alloy in different loading zones under two kinds of multi-cycle isothermal local forging (multi-cycle local near-? forging and multi-cycle conventional forging combined with near-? heat treatment) was investigated and the mechanical properties predicted. Under the first processing route, a microstructure with small grain size was obtained with a significant difference in morphology and composition

Zhichao Sun; Lei Liu; He Yang

2011-01-01

108

Expert system of cold forging defects using risk analysis tree network with fuzzy language  

Microsoft Academic Search

The authors have developed an expert system for detecting the risk of forging defects and their causes in cold processes. The system employs risk analysis for a computer-aided process planning system. In addition, the authors investigated topics that affect typical forging defects. Based on the investigation, the authors developed risk analysis tree networks to evaluate the risk potential and describe

T Ohashi; M Motomura

2000-01-01

109

Improved Thermoelectric Performance of p Type Bismuth Antimony Telluride Bulk Alloys Prepared by Hot Forging  

Microsoft Academic Search

The thermoelectric (TE) performance of Bi0.5Sb1.5Te3 polycrystalline alloys has been improved by a simple hot-forging process. No obvious texture was observed in the x-ray diffraction\\u000a (XRD) patterns of the hot-forged samples. Transport property measurements indicated that the hot-forged samples possessed\\u000a extremely low thermal conductivities. A maximum ZT value of ?1.1 at room temperature was obtained for the sample forged under

J. J. Shen; Z. Z. Yin; S. H. Yang; C. Yu; T. J. Zhu; X. B. Zhao

2011-01-01

110

Prediction of Microstructure in High-Strength Ductile Forging Parts  

SciTech Connect

Governmental, environmental and economic demands call for lighter, stiffer and at the same time cheaper products in the vehicle industry. Especially safety relevant parts have to be stiff and at the same time ductile. The strategy of this project was to improve the mechanical properties of forging steel alloys by employing a high-strength and ductile bainitic microstructure in the parts while maintaining cost effective process chains to reach these goals for high stressed forged parts. Therefore, a new steel alloy combined with an optimized process chain has been developed. To optimize the process chain with a minimum of expensive experiments, a numerical approach was developed to predict the microstructure of the steel alloy after the process chain based on FEM simulations of the forging and cooling combined with deformation-time-temperature-transformation-diagrams.

Urban, M.; Back, A.; Hirt, G. [Institute of Metal Forming (IBF), RWTH Aachen University, Aachen (Germany); Keul, C.; Bleck, W. [Institute of Ferrous Metallurgy (IEHK), RWTH Aachen University, Aachen (Germany)

2010-06-15

111

Investigations on Forging Dies with Ceramic Inserts by means of Finite-Element-Analysis  

SciTech Connect

The tools in hot forging processes are exposed to high thermal and mechanical loadings. Tempering of the tool edge layer occurs as a result of thermal loadings. This leads to a gradual hardness loss of the tool material and increase of wear over forging cycles. Hence, the tool life in hot forging is mainly limited by wear. An extension of the die service life can be achieved by the use of ceramic inserts. The integration of ceramics into the die base plate made of hot-work steel is realised by active brazing, whereby it possible to apply ceramic in region with high wear. It has to be ensured in the design process of ceramic inserts for forging dies that no critical tensile stresses occur in the ceramics. A reliable design of the ceramic inserts is possible only through consideration of brazing and forming process. The development of a Finite-Element-model for the design of forging dies with ceramic inserts is the intention of the work presented in this paper. At first the forging process with a conventional die is analyzed concerning abrasive die wear to identify regions with high wear risk applying a modified Archard model. Based on the results of wear calculation, a forging die with ceramic inserts is investigated in terms of joint stresses at the end of the active brazing process. Subsequently, the forging process considering the residual stresses caused by joining is simulated in order to obtain the die stress in use.

Behrens, B.-A.; Schaefer, F.; Bistron, M. [Institute of Metal Forming and Metal-Forming Machines, Leibniz University of Hannover, An der Universitaet 2, 30823 Garbsen (Germany)

2007-05-17

112

Investigations on Forging Dies with Ceramic Inserts by means of Finite-Element-Analysis  

NASA Astrophysics Data System (ADS)

The tools in hot forging processes are exposed to high thermal and mechanical loadings. Tempering of the tool edge layer occurs as a result of thermal loadings. This leads to a gradual hardness loss of the tool material and increase of wear over forging cycles. Hence, the tool life in hot forging is mainly limited by wear. An extension of the die service life can be achieved by the use of ceramic inserts. The integration of ceramics into the die base plate made of hot-work steel is realised by active brazing, whereby it possible to apply ceramic in region with high wear. It has to be ensured in the design process of ceramic inserts for forging dies that no critical tensile stresses occur in the ceramics. A reliable design of the ceramic inserts is possible only through consideration of brazing and forming process. The development of a Finite-Element-model for the design of forging dies with ceramic inserts is the intention of the work presented in this paper. At first the forging process with a conventional die is analyzed concerning abrasive die wear to identify regions with high wear risk applying a modified Archard model. Based on the results of wear calculation, a forging die with ceramic inserts is investigated in terms of joint stresses at the end of the active brazing process. Subsequently, the forging process considering the residual stresses caused by joining is simulated in order to obtain the die stress in use.

Behrens, B.-A.; Schäfer, F.; Bistron, M.

2007-05-01

113

Isothermal Forging of HIP'ed Superalloy.  

National Technical Information Service (NTIS)

Ni-base superalloy powders were consolidated by HIP for an isothermal, superplastic forging. As a result, the forging billet having enough superplasticity was obtained by HIPing the powder at a temperature below gamma-prime solvus. The superplastic behavi...

H. Takigawa

1985-01-01

114

Advanced rotor forgings for high-temperature steam turbines. Volume 1. Ingot and forging production. Final report  

SciTech Connect

Three advanced steel-melting processes - low-sulfur vacuum silicon deoxidation, electroslag remelting, and vacuum carbon deoxidation (VCD) - were applied to produce three CrMoV (ASTM A470, Class 8) steel forgings for steam turbine application. Ingots weighing about 100 t each were produced using these three processes, and rotors were forged with final weights of about 30 t each. Compared to the conventionally produced forgings, the advanced technology forgings show better tensile ductility and better uniformity along the radial and longitudinal directions. Charpy upper-shelf energy shows about 40% improvement, and no temper embrittlement was found using step-cooled and isothermal-aging treatments. Significant improvement in fracture toughness (K/sub IC/ and J/sub IC/) is realized for these forgings. Low-cycle fatigue life is better at high temperatures because of the absence of nonmetallic inclusions. Creep strength shows slight improvement. However, creep ductility is improved, probably because of low residual elements. The VCD forgings show excellent creep ductility, even with long lives. Both the toughness and creep properties are equal to or better than those of oil-quenched rotors produced by European practices. These improvements are attributed to cleaner steel, better control of ingot solidification, low residual elements (especially very low sulfur content), and the associated reduction of nonmetallic inclusions. These three rotors have been placed in service in three operating power plants in units rated at 520 MW each. Volume 1 of this report covers ingot and forging production, and volume 2 covers mechanical property evaluation.

Swaminathan, V.P.; Steiner, J.E.; Mitchell, A.

1986-05-01

115

Empirical and finite element approaches to forging die design: A state-of-the-art survey  

Microsoft Academic Search

A survey of research concerned with the use of computer-aided techniques to simulate the forging process and design forging\\u000a dies is presented here. Attention is focused on finite element models and empirical guidelines that have been developed in\\u000a this connection.

I. Haque; J. E. Jackson; T. Gangjee; A. Raikar

1987-01-01

116

A Comparison between the Properties of Solid Cylinders and Tube Products in Multi-Pass Hot Radial Forging Using Finite Element Method  

Microsoft Academic Search

Radial forging is an open die forging process used for reducing the diameter of shafts, tubes, stepped shafts and axels, and creating internal profiles for tubes such as rifling of gun barrels. In this work, a comprehensive study of multi-pass hot radial forging of short hollow and solid products are presented using 2-D axisymmetric finite element simulation. The workpiece is

A. Abedian; M. Poursina; H. Golestanian

2007-01-01

117

Simulation of Deformation Texture Evolution During Multi Axial Forging of Interstitial Free Steel  

NASA Astrophysics Data System (ADS)

Bulk texture measurement of multi-axial forged body center cubic interstitial free steel performed in this study using x-ray and neutron diffraction indicated the presence of a strong {101}<111> single texture component. Viscoplastic self-consistent simulations could successfully predict the formation of this texture component by incorporating the complicated strain path followed during this process and assuming the activity of {101}<111> slip system. In addition, a first-order estimate of mechanical properties in terms of highly anisotropic yield locus and Lankford parameter was also obtained from the simulations.

Gurao, N. P.; Kumar, P.; Sarkar, A.; Brokmeier, H.-G.; Suwas, Satyam

2013-04-01

118

Extraction of process specific photolithography model parameters  

NASA Astrophysics Data System (ADS)

In order to truly represent photolithography through simulation, the exposure, bake, and development models and model parameters must be accurate. Using the approach for the measurement of the in-situ development rate, developed in the first paper of this two paper series, the model parameters were extracted for Shipley 812 resist with Shipley MF312 developer. Development rates for exposures of 66, 90, and 114 mJ/cm2 were measured. It was discovered that the set of Kim model parameters, R1 through R6 were highly correlated with the combination of the Dill exposure parameters. Thus, for A equals 0.581 micrometers -1, B equals 0.082 micrometers (SUP>-1, C equals 0.013 cm2/mJ, the parameters R1 equals 25.559 micrometers /min, R2 equals 10.451 micrometers /min, R3 equals 1.879, R4 equals 0.112, R5 equals 1.586, R6 equals 0.000 micrometers , and (sigma) equals 0.0016 micrometers were extracted. A comparison of simulated data using the extracted model parameters with the measured data demonstrated the quality of the fit.

Drennan, Patrick G.; Smith, Bruce W.

1994-05-01

119

Possible Developments in the Cold Forging of Steel.  

National Technical Information Service (NTIS)

Cold forging of steel has been an accepted practice for a number of years and the paper examines the process and assesses possible developments. The cost of the starting billet has been shown to be a significant factor in the overall profitability of the ...

M. T. Watkins

1977-01-01

120

Summary of mechanical properties for JBK-75 forgings  

Microsoft Academic Search

Increased strengths can be achieved in precipitation-hardened stainless steels by deforming the steel and retaining a worked structure prior to aging. JBK-75 is one example of a superalloy which will respond to this type of thermomechanical processing. The present study was undertaken to determine the tensile properties of different forged shapes resulting from the combined effects of strain hardening and

R. L. Page; R. W. Krenzer

1979-01-01

121

Failure analysis of cold forging dies using FEA  

Microsoft Academic Search

The results presented within this paper represent part of a larger collaborated investigation being conducted by Trinity College, Dublin and an industrial partner. The particular cold forging process analysed was the method used to ‘trim’ a hexagonal shape on the head of a fastener. The fastener head geometry is achieved by forcing the die, known as a trim die because

Conor MacCormack; John Monaghan

2001-01-01

122

Finite Element Modeling of Superplastic Sheet Forming Processes. Identification of Rheological and Tribological Parameters by Inverse Method  

NASA Astrophysics Data System (ADS)

Superplastic forming is a thermoforming-like process commonly applied to titanium and aluminum alloys at high temperature and in specific conditions. This paper presents the application of an inverse analysis technique to the identification of rheological and tribological parameters. The method consists of two steps. First, two different kinds of forming tests have been carried out for rheological and tribological identification, using specific mold shapes. Accurate instrumentation and measurements have been done in order to feed an experimental database (values of appropriate observables). In a second step, the development of an inverse method has been carried out. It consists of the minimization of an objective function representative of the distance - in a least squares sense - between measured and calculated values of the observables. The algorithm, which is coupled with the finite element model FORGE2®, is based on a Gauss-Newton method, including a sensitivity matrix calculated by the semi-analytical method.

Bellet, Michel; Massoni, Elisabeth; Boude, Serge

2004-06-01

123

27 CFR 447.22 - Forgings, castings, and machined bodies.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Forgings, castings, and machined bodies. 447.22 ...Import List § 447.22 Forgings, castings, and machined bodies. Articles...partially completed state (such as forgings, castings, extrusions, and machined...

2013-04-01

124

22 CFR 121.10 - Forgings, castings and machined bodies.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Forgings, castings and machined bodies. 121.10 Section...of Articles § 121.10 Forgings, castings and machined bodies. Articles on...partially completed state (such as forgings, castings, extrusions and machined...

2013-04-01

125

Hot forging of melt quenched powder: Microstructure development and kinetics of densification  

NASA Astrophysics Data System (ADS)

Hot powder forging is a new process for making scalable and cost-effective nanocrystalline ceramics. It utilizes powder typically between 5 mum to 25 mum to nucleate very stable crystallite sizes well below 100 nm. These particles superplastically deform at relatively moderate temperature and stress. Hence, rapid densification at high creep rates is achieved with limited grain growth. A novel way to achieve high creep rate is to take advantage of partially amorphous powders that are obtained by one of the many available rapid quenching processes. Our study uses a plasma flame to melt the spray-dried aggregates of a particular composition and rapidly quench into water that results in metastable, optically transparent powder. The plasma sprayed powder is first hot pressed to obtain cylindrical pellets and then hot-forged at various stresses and temperatures to obtain optimum creep rates. Eutectic oxide compositions were studied due to their low melting point and better glass forming ability in an effort to optimize both the composition and processing parameters. Five binary compositions of alumina, zirconia and magnesium aluminate spinel and the effect of adding borosilicate glass on creep rates and microstructure were investigated. Their phase evolution and crystallite growth were examined in a detailed annealing study. The final densities after hot forging were composition dependent and ranged from 86% to 100% at 1350°C. Creep rates of the binary eutectic increased by an order of magnitude when alumina was substituted with spinel or when borosilicate glass was added. The highest creep rate obtained would correspond to 10-4 1/s for 40 MPa at 1350°C. SEM studies confirm that the densification is by plastic deformation of particles. TEM studies reveal nano-sized zirconia either in an alumina or spinel matrix. The grain morphology was cellular in compositions without glass and acicular in compositions with glass.

Keshavan, Hrishikesh

126

Knowledge-Based System for Die Configuration Design in Cold Forging  

Microsoft Academic Search

\\u000a We propose a knowledge-based system for process planning in cold forging. In our study, we had developed FORTEK-L (FORging\\u000a Technology of process planning using Expert Knowledge for Layout), which is widely applicable to various shapes and types\\u000a of equipment. In the next step, we have developed a knowledge-based die configuration design system, FORTEK-D (Die configuration\\u000a design), which can generate suitable

Osamu Takata; Tsubasa Mitani; Yuji Mure; Masanobu Umeda; Isao Nagasawa

2006-01-01

127

Dynamic simulation and neural network compliance control of an intelligent forging center  

Microsoft Academic Search

Automation of forging processes is important for both safety and efficiency in today's advanced manufacturing operations. This work supports the development of an Intelligent Open Die Forging System which will integrate state-of-the-art modelling techniques, automatic die selection and sequencing, full system dynamic simulation, automatic machine programming and coordination, and sensor-based process control to enable the production of more general and

K. W. Lilly; A. S. Melligeri

1996-01-01

128

Deformation Mechanisms in Tube Billets from Zr-1%Nb Alloy under Radial Forging  

SciTech Connect

Features of the deformation process by cold radial forging of tube billets from Zr-1%Nb alloy were reconstructed on the basis of X-ray data concerning their structure and texture. The cold radial forging intensifies grain fragmentation in the bulk of billet and increases significantly the latent hardening of potentially active slip systems, so that operation only of the single slip system becomes possible. As a result, in radially-forged billets unusual deformation and recrystallization textures arise. These textures differ from usual textures of {alpha}-Zr by the mutual inversion of crystallographic axes, aligned along the axis of tube.

Perlovich, Yuriy; Isaenkova, Margarita; Fesenko, Vladimir; Krymskaya, Olga [National Research Nuclear University 'Moscow Engineering Physics Institute', Kashirskoe shosse, 31, Moscow, 115409 (Russian Federation); Zavodchikov, Alexander [Perm Research Technological Institute, Hasan Heroes street, 41, Perm, 614990 (Russian Federation)

2011-05-04

129

Grippers for an Unmanned Forging Cell.  

National Technical Information Service (NTIS)

The following report describes the design and construction of two grippers for use in a flexible unmanned forging operation. The forging operation employs two large industrial robots, one to load and unload billets from a furnace at over 2000 deg F and a ...

M. R. Cutkosky E. Kurokawa

1983-01-01

130

Adaptive Signal Processing Relationship to Adaptive Observer Parameter Identification.  

National Technical Information Service (NTIS)

The acoustic signal processing method of LMS adaptive filtering is related to the problem of system parameter identification. Adaptive signal processing is dictated by the nonstationary ocean acoustic environment. Improvements in adaptive signal processin...

D. O. Molnar G. L. Mitchell R. G. Clapham

1977-01-01

131

Structure and hardness of steel 05 subjected to cold forging and heat treatment  

Microsoft Academic Search

Connective structural elements of pipelines (reducers, flanges, etc.) widely used in the chemical and fuel power industries\\u000a are commonly manufactured by hot forging. However, this method has a low technical and economic efficiency. The Institute\\u000a of Metal Physics of the Ural Branch of the Russian Academy of Sciences has developed a process of cold forging for manufacturing\\u000a preforms of pipeline

L. M. Voronova; L. S. Davydova; M. V. Degtyarev; B. I. Kamenetskii; T. I. Chashchukhina

1997-01-01

132

Failure analysis of hot forging dies for automotive components  

Microsoft Academic Search

Influencing variables and causes of hot forging die failures for automotive components are summarized. Characteristics of hot forging die failures are exemplified. An important role of microfractography is stressed in engineering failure analysis for hot forging die failures.Then failure analyzed examples for hot forging die failures and their countermeasures are presented with influencing variables such as die materials, die design,

Ryuichiro Ebara; Katsuaki Kubota

2008-01-01

133

Combining Noise Factors and Process Parameters in a Response Surface  

SciTech Connect

This presentation covers the strategy and analysis of an experiment to characterize a gas tungsten arc welding process. The experiment combined four uncontrolled noise factors and four controlled process parameters. A nontraditional response surface design was employed. Multiple responses were modeled. Optimal settings for the process parameters to successfully weld the widest range of the pertinent product features were identified. Thus, the process was made ''robust'' against ''noise'' factors. Comparisons are made between the experimental and analytical approach taken versus the Taguchi style of experimentation and analysis. This comparison is mainly done with respect to the information gained, such as product design criteria, incoming material specifications, and process adjustments for nonconforming material.

Wyckoff, J.J.

1998-03-19

134

Influence of processing parameters on the quality of soycurd (tofu)  

Microsoft Academic Search

Tofu, a non-fermented soybean curd is a nutritious and digestible product with a high quality protein. Tofu making procedure\\u000a includes soaking of beans, grinding, filtering, boiling, coagulating and moulding. The flavour, quality and the texture of\\u000a tofu produced is significantly influenced by its processing parameters. Studies were carried out on the processing parameters\\u000a like solid content of milk, thermal treatment

C. R. Rekha; G. Vijayalakshmi

135

Computer simulation of the forging of fine grain IN-718 alloy  

SciTech Connect

In recent years, there has been great emphasis on the use of computer-aided tools in process design. The key to the success of any computer modeling is the accurate knowledge of the mechanical and thermal properties of the various components of a manufacturing system. In order to develop a data base of forging properties of the nickel-base alloy IN-718, isothermal constant strain-rate compression tests were conducted on the annealed fine-grain material over the temperature range 871 C to 1,149 C (1,600 F to 2,100 F) and strain-rate range 0.001 to 10 s[sup [minus]1]. Empirical relationships among flow stress, strain rate, and temperature developed based on these tests, along with experimentally measured heat-transfer and friction coefficients, were used in the program ALPID to simulate nonisothermal forging of double-cone specimens. The simulation results were compared with actual forging in an industrial forge press. The good agreement between simulation and forging results indicates that when a complete data base of materials properties is available, computer modeling can be used effectively to study the forging process.

Srinivasan, R.; Deshpande, U.; Weiss, I. (Wright State Univ., Dayton, OH (United States). Mechanical and Materials Engineering Dept.); Ramnarayan, V. (Concurrent Technologies Corp., Johnstown, PA (United States)); Jain, V. (Univ. of Dayton, OH (United States). Mechanical and Aerospace Engineering Dept.)

1993-09-01

136

29 CFR 1910.218 - Forging machines.  

Code of Federal Regulations, 2013 CFR

...anchored to foundations sufficient to support them according to applicable engineering...dimensions shown in Table O-11. (2) Hydraulic forging presses. When dies are being...following shall be accomplished: (i) The hydraulic pumps and power apparatus shall be...

2013-07-01

137

A Manual on Fundamentals of Forging Practice.  

National Technical Information Service (NTIS)

The information presented in the Manual was obtained from the literature, from industrial sources, and from a laboratory-scale experimental program designed to study significant forging characteristics of several typical alloys. This information can be di...

A. M. Sabroff F. W. Boulger H. J. Henning J. W. Spretnak

1964-01-01

138

Preform Design for Large-Sized Frame Forging of Ti-Alloy Based on 3-D Electrostatic Field Simulation and Geometric Transformation  

NASA Astrophysics Data System (ADS)

Large-sized frame forging of Ti-alloy is an important forced component of aircraft. The frame forging has complicated shape which leads to great difficulties in deformation. Some defects may be produced during the forming process such as un-filling or overlapping. Preform design is an effective method for producing qualified forging. In this article, a new method based on 3-D electrostatic field simulation is proposed to design preform of a large-sized frame forging of Ti-alloy and a geometric transformation method is introduced to obtain the preform dimension. In order to select more suitable preform of large-sized frame forging, FEM software Deform-3D is employed to simulate the isothermal forming process of designed preform. Deformation uniformity index ? is introduced as a criterion to judge the forging quality and the most appropriate preform is obtained by virtual orthogonal test design.

Cai, Jun; Li, Fuguo; Liu, Taiying

2011-12-01

139

INVESTIGATION OF ELECTROCHEMICAL PARAMETERS INTO AN ELECTROCHEMICAL MACHINING PROCESS  

Microsoft Academic Search

Electrochemical machining (ECM) is a process where the surface of a part is removed via an anodic charge transfer. Electropolishing, electrochemica l deburring, or radiusing are electrochemical machining processes where the metal removal must be uniform or localized, respectively. ECM is affected by many parameters such as machining gap, electric field modulation, electrolyte properties, and flow rate. This paper focuses

Jenny J. Sun; E. Jennings Taylor; Lawrence E. Gebhart; Chengdong D. Zhou; Jeffrey M. Eagleton; Robert P. Renz

140

Screw thread parameter measurement system based on image processing method  

NASA Astrophysics Data System (ADS)

In the industrial production, as an important transmission part, the screw thread is applied extensively in many automation equipments. The traditional measurement methods of screw thread parameter, including integrated test methods of multiparameters and the single parameter measurement method, belong to contact measurement method. In practical the contact measurement exists some disadvantages, such as relatively high time cost, introducing easily human error and causing thread damage. In this paper, as a new kind of real-time and non-contact measurement method, a screw thread parameter measurement system based on image processing method is developed to accurately measure the outside diameter, inside diameter, pitch diameter, pitch, thread height and other parameters of screw thread. In the system the industrial camera is employed to acquire the image of screw thread, some image processing methods are used to obtain the image profile of screw thread and a mathematics model is established to compute the parameters. The C++Builder 6.0 is employed as the software development platform to realize the image process and computation of screw thread parameters. For verifying the feasibility of the measurement system, some experiments were carried out and the measurement errors were analyzed. The experiment results show the image measurement system satisfies the measurement requirements and suitable for real-time detection of screw thread parameters mentioned above. Comparing with the traditional methods the system based on image processing method has some advantages, such as, non-contact, easy operation, high measuring accuracy, no work piece damage, fast error analysis and so on. In the industrial production, this measurement system can provide an important reference value for development of similar parameter measurement system.

Rao, Zhimin; Huang, Kanggao; Mao, Jiandong; Zhang, Yaya; Zhang, Fan

2013-08-01

141

A dimensionless parameter model for arc welding processes  

NASA Astrophysics Data System (ADS)

A dimensionless parameter model previously developed for CO2 laser beam welding has been shown to be applicable to GTAW and PAW autogenous arc welding processes. The model facilitates estimates of weld size, power, and speed based on knowledge of the material's thermal properties. The dimensionless parameters can also be used to estimate the melting efficiency, which eases development of weld schedules with lower heat input to the weldment. The mathematical relationship between the dimensionless parameters in the model has been shown to be dependent on the heat flow geometry in the weldment.

Fuerschbach, P. W.

142

A dimensionless parameter model for arc welding processes  

SciTech Connect

A dimensionless parameter model previously developed for C0{sub 2} laser beam welding has been shown to be applicable to GTAW and PAW autogenous arc welding processes. The model facilitates estimates of weld size, power, and speed based on knowledge of the material`s thermal properties. The dimensionless parameters can also be used to estimate the melting efficiency, which eases development of weld schedules with lower heat input to the weldment. The mathematical relationship between the dimensionless parameters in the model has been shown to be dependent on the heat flow geometry in the weldment.

Fuerschbach, P.W.

1994-12-31

143

Sensitivity analysis for process parameters influencing weld quality in robotic GMA welding process  

Microsoft Academic Search

Generally, the quality of a weld joint is strongly influenced by process parameters during the welding process. In order to achieve high quality welds, mathematical models that can predict the bead geometry to accomplish the desired mechanical properties of the weldment should be developed. This paper focuses on development of mathematical models for the selection of process parameters and the

I. S. Kim; Y. J. Jeong; I. J. Son; I. J. Kim; J. Y. Kim; I. K. Kim; Prasad K. D. V. Yaragada

2003-01-01

144

Non-isothermal FEM analyses of large-strain back extrusion forging  

SciTech Connect

Back extrusion forging is a complex metal forming operation dominated by large-strain, non-isothermal deformation. NIKE2D, a fully vectorized implicit finite-element program developed at Lawrence Livermore National Laboratory, was applied to a two-stage isothermal back extrusion forging process. Modeling of the forging process required special features in the FEM code such as friction and interactive rezoning that allows for remeshing of the distorted mesh while maintaining a complete history of all the state variables. To model conditions of the non-isothermal forging process required implementing TOPAZ2D, our LLNL-developed two-dimensional implicit finite element code for heat conduction analysis, as a subroutine into NIKE2D. The fully coupled version maintains all the original features of both codes and can account for the contribution of heat generation during plastic deformation. NIKE/TOPAZ-2D was applied to the piercing operation of the back extrusion forging process. The thermal deformation history of the die, punch, and workpiece and the effective plastic strains were calculated.

Flower, E.C.; Hallquist, J.O.; Shapiro, A.B.

1986-06-19

145

Prediction of food thermal process evaluation parameters using neural networks  

Microsoft Academic Search

Two neural networks (ANN) were developed to predict thermal process evaluation parameters g and fh\\/U (the ratio of heating rate index to the sterilizing value), respectively. The temperature change required for the thermal destruction curve to traverse one log cycle (z), cooling lag factor (jc) and fh\\/U were input variables for predicting g and z, while jc and g were

G. S Mittal; J Zhang

2002-01-01

146

Effects of process parameters on material removal rate in WEDM  

Microsoft Academic Search

Purpose: In this paper, the effects of various process parameters of WEDM like pulse on time (TON), pulse off time (TOFF), gap voltage (SV), peak current (IP), wire feed (WF) and wire tension (WT) have been investigated to reveal their impact on material removal rate of hot die steel (H-11) using one variable at a time approach. The optimal set

H. Singh; R. Garg

147

Empirical processes with estimated parameters under auxiliary information  

Microsoft Academic Search

Empirical processes with estimated parameters are a well established subject in nonparametric statistics. In the classical theory they are based on the empirical distribution function which is the nonparametric maximum likelihood estimator for a completely unknown distribution function. In the presence of some “nonparametric” auxiliary information about the distribution, like a known mean or a known median, for example, the

Michael Genz; Erich Haeusler

2006-01-01

148

Effects of Parameters of Spectrally Remote Frequencies on Binaural Processing  

Microsoft Academic Search

Three experiments and a computer simulation of human subjects' behavior were conducted to gain insight into how processing of interaural time (or phase) differences at low frequencies is affected by the interaural parameters of other spectral regions. The task of the first two experiments was to detect an interaural phase shift of a 20-Hz wide band of noise centered on

Anthony Nelson Grange

1995-01-01

149

Quenching and Cold-Work Residual Stresses in Aluminum Hand Forgings : Contour Method Measurement and FEM Prediction  

Microsoft Academic Search

The cold-compression stress relief process used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings does not fully relieve the stresses. This study measured and predicted the residual stress in 7050-T74 (solution heat treated, quenched, and artificially overaged) and 7050-T7452 (cold compressed prior to aging) hand forgings. The manufacturing process was simulated by finite element analysis. First, a

Michael B. Prime; Mark A. Newborn; John A. Balog

2003-01-01

150

27 CFR 447.22 - Forgings, castings, and machined bodies.  

Code of Federal Regulations, 2011 CFR

...true Forgings, castings, and machined bodies. 447.22 Section 447.22 Alcohol...22 Forgings, castings, and machined bodies. Articles on the U.S. Munitions...castings, extrusions, and machined bodies) which have reached a stage in...

2011-04-01

151

Valley Forge National Historical Park Business Plan, 2006.  

National Technical Information Service (NTIS)

When citizens convened in the 1870s to protect Valley Forge, their common vision was the preservation of a significant and meaningful place that inspired the Continental Army. Valley Forge continues to inspire Americans a century later. Since the founding...

2006-01-01

152

Effect of Process Parameters on Catalytic Incineration of Solvent Emissions  

PubMed Central

Catalytic oxidation is a feasible and affordable technology for solvent emission abatement. However, finding optimal operation conditions is important, since they are strongly dependent on the application area of VOC incineration. This paper presents the results of the laboratory experiments concerning four most central parameters, that is, effects of concentration, gas hourly space velocity (GHSV), temperature, and moisture on the oxidation of n-butyl acetate. Both fresh and industrially aged commercial Pt/Al2O3 catalysts were tested to determine optimal process conditions and the significance order and level of selected parameters. The effects of these parameters were evaluated by computer-aided statistical experimental design. According to the results, GHSV was the most dominant parameter in the oxidation of n-butyl acetate. Decreasing GHSV and increasing temperature increased the conversion of n-butyl acetate. The interaction effect of GHSV and temperature was more significant than the effect of concentration. Both of these affected the reaction by increasing the conversion of n-butyl acetate. Moisture had only a minor decreasing effect on the conversion, but it also decreased slightly the formation of by products. Ageing did not change the significance order of the above-mentioned parameters, however, the effects of individual parameters increased slightly as a function of ageing.

Ojala, Satu; Lassi, Ulla; Peramaki, Paavo; Keiski, Riitta L.

2008-01-01

153

Microstructure Evolution of Superalloy for Large Exhaust Valve during Hot Forging  

Microsoft Academic Search

The nickel-based alloy Nimonic 80A possesses strength, and corrosion, creep and oxidation resistance at high temperature. These products are used for aerospace, marine engineering and power generation, etc. The control of forging parameters such as strain, strain rate, temperature and holding time is important because the microstructure change in hot working affects the mechanical properties. It is necessary to understand

H. S. Jeong; J. R. Cho; H. C. Park

2004-01-01

154

Microstructure prediction of Nimonic 80A for large exhaust valve during hot closed die forging  

Microsoft Academic Search

The nickel-based alloy Nimonic 80A possesses strength, and corrosion, creep and oxidation resistance at high temperature. These products are used for aerospace, marine engineering and power generation, etc. The control of forging parameters such as strain, strain rate, temperature and holding time is important because the microstructure change in hot working affects the mechanical properties. It is necessary to understand

H. S. Jeong; J. R. Cho; H. C. Park

2005-01-01

155

Co-Operative Training in the Sheffield Forging Industry  

ERIC Educational Resources Information Center

|Purpose: The purpose of this paper is to give details of an operation carried out in Sheffield to increase the recruitment of young men into the steel forging industry. Design/methodology/approach: The Sheffield Forges Co-operative Training Scheme was designed to encourage boys to enter the forging industry and to provide them with training and…

Duncan, R.

2008-01-01

156

NEW TOOL STEEL FOR WARM AND HOT FORGING  

Microsoft Academic Search

Currently there are few tool steels which are particularly s uitable for warm forging. A number of hot work tool steels, high speed steels and even cold work tool steels are used. Compared to hot forging (>1050 ?C) the loads required may be doubled. Compared to cold forging, the workpiece temper- ature is high (600 ?C-900 ?C), and therefore thermal

K. Fisher; H. Schweiger; J. Hasenberger; H. Dremel

157

76 FR 50755 - Heavy Forged Hand Tools From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-457-A-D (Third Review)] Heavy Forged Hand Tools From China Determinations On the basis...antidumping duty orders on heavy forged hand tools from China would be likely to lead to continuation...August 2011), entitled Heavy Forged Hand Tools From China: Investigation Nos....

2011-08-16

158

Development of high purity large forgings for nuclear power plants  

Microsoft Academic Search

The recent increase in the size of energy plants has been supported by the development of manufacturing technology for high purity large forgings for the key components of the plant. To assure the reliability and performance of the large forgings, refining technology to make high purity steels, casting technology for gigantic ingots, forging technology to homogenize the material and consolidate

Yasuhiko Tanaka; Ikuo Sato

2011-01-01

159

Quality insurance for optimal parameters determination for stereolithography process  

NASA Astrophysics Data System (ADS)

The main objective of this paper is to present the first results of a quality insurance study about the global 'CAD/stereolithography/vacuum casting' process. The first experiments are mainly related to stereolithography. The significant parameters concerning dimensional and geometric accuracy of the parts are highlighted. A Taguchi approach allowed to build an experiment procedure. The results are presented and the conclusion allows to deduce concrete elements on part positioning in the stereolithography machine chamber for high quality parts.

Wich, R.; Bernard, Alain; Bocquet, Jean Claud

1997-01-01

160

Reduction in post forging errors for aerofoil forging using finite element simulation and optimization  

NASA Astrophysics Data System (ADS)

This paper reports on recent work in the development of a finite element (FE) based forging optimization methodology. It utilizes the commercial FE package ABAQUS and the optimization code VisualDOC. Taking into account the effect of die and press elastic deflections and thermal distortion in cooling, a direct compensation approach and optimized weighting factor method are used to achieve the optimized die shape for improved dimensional accuracy of forged aerofoil blades. The significant predicted reduction in aerofoil shape errors using a single 2D section from a forged nickel-based blade demonstrates the efficiency and potential for applying this approach to more complex, realistic and industrially relevant 3D forging problems.

Ou, H.; Lan, J.; Armstrong, C. G.; Price, M. A.; Walløe, S. J.; Ward, M. J.

2006-03-01

161

Ferrous Powder Metal Preform Forging Methods.  

National Technical Information Service (NTIS)

The research is designed to examine the three ferrous powder metal preform forging methods currently under consideration by the U.S. Army. The examination will answer the following question: which method is best for a particular complexity of parts. One o...

M. A. Perlman

1975-01-01

162

Forging Inclusive Solutions: Experiential Earth Charter Education  

ERIC Educational Resources Information Center

|Forging Inclusive Solutions describes the aims, methodology and outcomes of Inclusive Leadership Adventures, an experiential education curriculum for exploring the Earth Charter. Experiential education builds meaningful relationships, skills, awareness and an inclusive community based on the Earth Charter principles. When we meet people where…

Hill, Linda D.

2010-01-01

163

Forging Inclusive Solutions: Experiential Earth Charter Education  

ERIC Educational Resources Information Center

Forging Inclusive Solutions describes the aims, methodology and outcomes of Inclusive Leadership Adventures, an experiential education curriculum for exploring the Earth Charter. Experiential education builds meaningful relationships, skills, awareness and an inclusive community based on the Earth Charter principles. When we meet people where they…

Hill, Linda D.

2010-01-01

164

Temperature changes and loads during hot-die forging of a gamma titanium–aluminide alloy  

Microsoft Academic Search

Non-isothermal forging is a non-steady state deformation process since temperatures of die, workpiece and environment are different from each other. The workpiece temperature decreases during the process by heat transfer to the dies and the environment. On the other hand, deformation heating can increase the workpiece temperature. The deformation loads depend not just on the initial temperature of the workpiece

Raghavan Srinivasan; Mahendramohan Balathandayuthapani; Wenying Yan

2005-01-01

165

Effect of Forging Strain Rate and Deformation Temperature on the Mechanical Properties of Warm-Worked 304L Stainless Steel  

SciTech Connect

Stainless steel 304L forgings were produced with four different types of production forging equipment – hydraulic press, mechanical press, screw press, and high-energy rate forging (HERF). Each machine imparted a different nominal strain rate during the deformation. The final forgings were done at the warm working (low hot working) temperatures of 816 ?C, 843 ?C, and 871 ?C. The objectives of the study were to characterize and understand the effect of industrial strain rates (i.e. processing equipment), and deformation temperature on the mechanical properties for the final component. Some of the components were produced with an anneal prior to the final forging while others were deformed without the anneal. The results indicate that lower strain rates produced lower strength and higher ductility components, but the lower strain rate processes were more sensitive to deformation temperature variation and resulted in more within-part property variation. The highest strain rate process, HERF, resulted in slightly lower yield strength due to internal heating. Lower processing temperatures increased strength, decreased ductility but decreased within-part property variation. The anneal prior to the final forging produced a decrease in strength, a small increase in ductility, and a small decrease of within-part property variation.

Nathan T Switzner

2010-02-01

166

Artificial neural network modeling of phase volume fraction of Ti alloy under isothermal and non-isothermal hot forging conditions  

Microsoft Academic Search

An artificial neural network (ANN) model was applied to simulate the phase volume fraction of titanium alloy under isothermal\\u000a and non-isothermal hot forging condition. For isothermal hot forging process, equilibrium phase volume fraction at specific\\u000a temperature was predicted. For this purpose, chemical composition of six alloy elements (i.e. Al, V, Fe, O, N, and C) and\\u000a specimen temperature were chosen

J. H. Kim; N. S. Reddy; J. T. Yeom; C. S. Lee; N. K. Park

2007-01-01

167

Parameters in selective laser melting for processing metallic powders  

NASA Astrophysics Data System (ADS)

The paper presents results of studies on Selective Laser Melting. SLM is an additive manufacturing technology which may be used to process almost all metallic materials in the form of powder. Types of energy emission sources, mainly fiber lasers and/or Nd:YAG laser with similar characteristics and the wavelength of 1,06 - 1,08 microns, are provided primarily for processing metallic powder materials with high absorption of laser radiation. The paper presents results of selected variable parameters (laser power, scanning time, scanning strategy) and fixed parameters such as the protective atmosphere (argon, nitrogen, helium), temperature, type and shape of the powder material. The thematic scope is very broad, so the work was focused on optimizing the process of selective laser micrometallurgy for producing fully dense parts. The density is closely linked with other two conditions: discontinuity of the microstructure (microcracks) and stability (repeatability) of the process. Materials used for the research were stainless steel 316L (AISI), tool steel H13 (AISI), and titanium alloy Ti6Al7Nb (ISO 5832-11). Studies were performed with a scanning electron microscope, a light microscopes, a confocal microscope and a ?CT scanner.

Kurzynowski, Tomasz; Chlebus, Edward; Ku?nicka, Bogumi?a; Reiner, Jacek

2012-02-01

168

Optimization of Galvannealing Parameters through Numerical Modeling of Galvannealing Process  

NASA Astrophysics Data System (ADS)

In the galvannealing process, a galvanized sheet is subjected to an annealing treatment to transform the zinc-coated steel sheet to iron-zinc alloy-coated steel. In the present work, the galvannealing process has been treated as a binary multiphase diffusional phase transformation reaction, and a rigorous mathematical model has been developed to simulate the galvannealing process. The results obtained by the model have been compared with experimental as well as plant data, and the results have been found to be in good agreement. The model prediction shows that the excessive growth of undesirable ? and ?1 phases takes place when the iron content in the coating exceeds around 11 pct during galvannealing. It has also been observed that decreasing the line speed to obtain the desired iron content in the coating leads to excessive growth of the undesirable ? and ?1 phases. It has been concluded that the developed mathematical model can be used to optimize the galvannealing parameters.

Verma, A. K.; Chandra, Sanjay; Bandyopadhyay, N.; Dhindaw, B. K.; Misra, R. D. K.

2009-05-01

169

Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740  

SciTech Connect

In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.

Ludtka, G.M.; Smith, G.

2007-11-19

170

Barrier layer multilayer ceramic capacitor processing: effects of termination and plating process parameters  

Microsoft Academic Search

The authors report studies on the effects of termination and plating process parameters on fabrication of multilayer ceramic capacitors intended for use as surface-mount devices. The parameters in this study included: three capacitor lots, eight termination ink types, seven termination band heights, two termination crown heights, the number of columns for nickel plating, and the time and current density for

F. R. Anderson; R. Haynes; S. C. Pinault

1989-01-01

171

Estimating demographic parameters using hidden process dynamic models.  

PubMed

Structured population models are widely used in plant and animal demographic studies to assess population dynamics. In matrix population models, populations are described with discrete classes of individuals (age, life history stage or size). To calibrate these models, longitudinal data are collected at the individual level to estimate demographic parameters. However, several sources of uncertainty can complicate parameter estimation, such as imperfect detection of individuals inherent to monitoring in the wild and uncertainty in assigning a state to an individual. Here, we show how recent statistical models can help overcome these issues. We focus on hidden process models that run two time series in parallel, one capturing the dynamics of the true states and the other consisting of observations arising from these underlying possibly unknown states. In a first case study, we illustrate hidden Markov models with an example of how to accommodate state uncertainty using Frequentist theory and maximum likelihood estimation. In a second case study, we illustrate state-space models with an example of how to estimate lifetime reproductive success despite imperfect detection, using a Bayesian framework and Markov Chain Monte Carlo simulation. Hidden process models are a promising tool as they allow population biologists to cope with process variation while simultaneously accounting for observation error. PMID:22373775

Gimenez, Olivier; Lebreton, Jean-Dominique; Gaillard, Jean-Michel; Choquet, Rémi; Pradel, Roger

2012-02-18

172

Parameter-free scaling relation for nonequilibrium growth processes.  

PubMed

We discuss a parameter-free scaling relation that yields a complete data collapse for large classes of nonequilibrium growth processes. We illustrate the power of this scaling relation through various growth models, such as the competitive growth model with random deposition and random deposition with surface diffusion or the restricted solid-on-solid model with different nearest-neighbor height differences, as well as through a deposition model with temperature-dependent diffusion. The scaling relation is compared to the familiar Family-Vicsek relation, and the limitations of the latter are highlighted. PMID:19518465

Chou, Yen-Liang; Pleimling, Michel

2009-05-14

173

On-line estimation of concentration parameters in fermentation processes*  

PubMed Central

It has long been thought that bioprocess, with their inherent measurement difficulties and complex dynamics, posed almost insurmountable problems to engineers. A novel software sensor is proposed to make more effective use of those measurements that are already available, which enable improvement in fermentation process control. The proposed method is based on mixtures of Gaussian processes (GP) with expectation maximization (EM) algorithm employed for parameter estimation of mixture of models. The mixture model can alleviate computational complexity of GP and also accord with changes of operating condition in fermentation processes, i.e., it would certainly be able to examine what types of process-knowledge would be most relevant for local models’ specific operating points of the process and then combine them into a global one. Demonstrated by on-line estimate of yeast concentration in fermentation industry as an example, it is shown that soft sensor based state estimation is a powerful technique for both enhancing automatic control performance of biological systems and implementing on-line monitoring and optimization.

Xiong, Zhi-hua; Huang, Guo-hong; Shao, Hui-he

2005-01-01

174

Effect of process parameters on surface morphology in MRF  

NASA Astrophysics Data System (ADS)

Spot surface morphology can be considered as a footprint of the removal process in magnetorheological finishing (MRF). When properly processed, it can account for the performance of the MR fluid in polishing. Experiments were done using different conditions to vary removal rate and evaluate the resulting effect on microroughness and the overall spot surface morphology. Such experiments have been performed on two optical glasses, with several different MR fluids and a wide range of machine parameter settings. Atomic force microscope (AFM) measurements show that the surface morphology has a strong dependence on the abrasive type in the MR fluid. Interferometry measurements show that the roughness inside the spot increases with the rate of the material removal.

Shorey, Aric B.; Gorodkin, Sergei; Kordonski, William

2003-05-01

175

Sensitivity analysis on parameters and processes affecting vapor intrusion risk.  

PubMed

A one-dimensional numerical model was developed and used to identify the key processes controlling vapor intrusion risks by means of a sensitivity analysis. The model simulates the fate of a dissolved volatile organic compound present below the ventilated crawl space of a house. In contrast to the vast majority of previous studies, this model accounts for vertical variation of soil water saturation and includes aerobic biodegradation. The attenuation factor (ratio between concentration in the crawl space and source concentration) and the characteristic time to approach maximum concentrations were calculated and compared for a variety of scenarios. These concepts allow an understanding of controlling mechanisms and aid in the identification of critical parameters to be collected for field situations. The relative distance of the source to the nearest gas-filled pores of the unsaturated zone is the most critical parameter because diffusive contaminant transport is significantly slower in water-filled pores than in gas-filled pores. Therefore, attenuation factors decrease and characteristic times increase with increasing relative distance of the contaminant dissolved source to the nearest gas diffusion front. Aerobic biodegradation may decrease the attenuation factor by up to three orders of magnitude. Moreover, the occurrence of water table oscillations is of importance. Dynamic processes leading to a retreating water table increase the attenuation factor by two orders of magnitude because of the enhanced gas phase diffusion. PMID:22392684

Picone, Sara; Valstar, Johan; van Gaans, Pauline; Grotenhuis, Tim; Rijnaarts, Huub

2012-03-30

176

Effects of Parameters of Spectrally Remote Frequencies on Binaural Processing  

NASA Astrophysics Data System (ADS)

Three experiments and a computer simulation of human subjects' behavior were conducted to gain insight into how processing of interaural time (or phase) differences at low frequencies is affected by the interaural parameters of other spectral regions. The task of the first two experiments was to detect an interaural phase shift of a 20-Hz wide band of noise centered on 500 Hz. In the first experiment, the target band was surrounded by diotic noise of varying bandwidth. The noise outside of the diotic band was interaurally uncorrelated. Twenty statistically independent samples of each condition, each with an identical target interaural phase shift, were stored in a computer, and detection performance was measured for each sample. Percent correct ranged from chance to over 90% for all subjects in all conditions. The data were accounted for by a comparison of the cross-correlation coefficient of a filter pair centered on the target with the cross-correlation of surrounding filters. A computer simulation of an experiment that measured IPD detection thresholds using an identical stimulus (Grange, 1991) was run, to see if behavior could be modelled assuming a fixed binaural processing bandwidth. The simulation data did not fit the behavioral data well, and it was argued that a fixed processing band was inadequate to describe binaural processing; however, there were several potential cues that were not incorporated into the simulation. In the second experiment, interaural parameters of off-target frequencies varied over time. Detection performance improved when the interaural phase of the remote frequencies initially differed from that of the target band, suggesting that listeners can differentially weight spectral regions on the basis of their interaural parameters. A general model was suggested that includes spectral weighting prior to combination of interaural information across frequencies. The final experiment was a replication of a tone -in-noise detection experiment (Sondhi and Guttman, 1966) using a more rigorous psychophysical procedure. The interaural configuration of the noise was similar to that used in the previous two experiments, and the discussion includes an interpretation of the data in terms of the previously mentioned model.

Grange, Anthony Nelson

1995-01-01

177

Open-die forging of sintered cylindrical billets: an analytical approach  

Microsoft Academic Search

The open-die forging (upsetting) of sintered porous materials is used widely as one of the key metal processing operations for fabricating various engineering products, and in some cases, for predicting the mechanical properties of such materials. In the present paper, an analysis of the upsetting of axisymmetric cylindrical billets of porous materials is made on the basis of plasticity theory.

A. G. Mamalis; G. L. Petrossian; D. E. Manolakos

1999-01-01

178

The influence of thickness of CrN coating on the durability of hot forging dies  

NASA Astrophysics Data System (ADS)

This article presents results which enabled the determination of the role of CrN coating and the influence of its thickness on the effectiveness of hybrid layer "nitrided layer / CrN coating" in the process of increasing the durability of forging dies. Dies coated with hybrid layers "nitrided layer / CrN coating" with various CrN coating thickness were — after different maintenance periods — subjected to metallographic testing, 3D shape testing and SEM analysis. Hardness distribution was also determined. The obtained results revealed that for all tested dies, independently from CrN coating thickness, the main mechanisms of their destruction was mechanical and thermal fatigue, and plastic deformation. It has been shown that the main role of CrN coating in the hybrid layer "nitrided layer / PVD coating" is to counteract a high temperature influence the source of which is forging on die material. In order to do so the CrN coating should be characterized by a considerably lower thermal conductivity coefficient to steel and low hardness so that it can efficiently resist fatigue processes in the forging process. Based on testing conducted by means of the sin 2 ? method, it was revealed that internal stresses are vitally important for CrN coating for fatigue resistance of hybrid layer "nitrided layer / CrN coating" during the forging process.

Smolik, Jerzy

2011-06-01

179

Changes induced by process parameters in oxide layers grown by the PEO process on Al alloys  

Microsoft Academic Search

The present work focuses on the influence of the distance between the substrate and the counter electrodes on the plasma electrolytic oxidation process. Depending on the waveform parameters of the applied current, two working regimes may be achieved referred to as “soft PEO regime” and “conventional (arcing) PEO regime.” At constant process duration, it is shown that the layer thickness

A. Melhem; G. Henrion; T. Czerwiec; J. L. Briançon; T. Duchanoy; F. Brochard; T. Belmonte

2011-01-01

180

Selection of Process Parameters for Sodium Removal via the Water Vapor Nitrogen Process.  

National Technical Information Service (NTIS)

This report reviews the water vapor nitrogen (WVN) process for removing sodium from stainless steel equipment, with emphasis on the basis for selecting final operating parameters. the process includes vapor treatment with 5% water at 160 F to 190 F, hot w...

M. Crippe

1977-01-01

181

Open Collaboration within Corporations Using Software Forges  

Microsoft Academic Search

This article describes our experiences using open source software development practices at SAP. SAP is a major software developer and leader in business applications. We've found that open source practices can complement traditional top-down software development with bottom-up collective intelligence. Software forges offer a mechanism for advancing the adoption of open source best practices within corporations. We illustrate our experiences

Dirk Riehle; John Ellenberger; Tamir Menahem; Boris Mikhailovski; Yuri Natchetoi; Barak Naveh; Thomas Odenwald

2009-01-01

182

Evaluation of contact conditions in hot forging of pure aluminum using ultrasonic examination  

Microsoft Academic Search

In isothermal upset forging of pure aluminum, the change in the contact condition and the lubricant behavior were evaluated by continuously measuring the ultrasonic reflection intensity from the contact interface between the tool (die) and workpiece. The relationships between ultrasonic reflection intensity, forging temperature, lubrication, forging pressure and workpiece surface during forging were examined. Depending on forging temperature, the conditions

Hiroyuki Saiki; Zhi Hong Zhan; Yasuo Marumo; Liqun Ruan; Toshiharu Morooka; Shin-Ichi Tatsuda

2006-01-01

183

Spark-eroded particles: Influence of processing parameters  

NASA Astrophysics Data System (ADS)

Ni particles were prepared by spark erosion in a fixed-gap apparatus, and in the usual ``shaker-pot'' assembly, in an investigation of the influence of various processing parameters on the particles' properties. The sizes of the particles were studied as functions of spark energies ranging from 10 ?J to 1 J, and a scaling relation derived from a simple model was verified. Several different static and rotating electrode configurations were compared with respect to their suitability for producing significant yields of small particles. The advantages of stirring the dielectric with the fixed-gap apparatus and of rotating the electrodes were demonstrated. Water, kerosene, and liquid argon and nitrogen were used as dielectric liquids. When compounds were formed, the reaction with the dielectric proceeded inversely with particle size. Spark erosion in kerosene at low spark energies, followed by annealing, proved to be an effective method to produce fine nickel particles.

Carrey, J.; Radousky, H. B.; Berkowitz, A. E.

2004-02-01

184

Numerical life prediction of mechanical fatigue for hot forging tools  

Microsoft Academic Search

In the forging industry, tools represent an important part in term of production and costs. Enhancing their life cycle is\\u000a then a challenging issue. Several mechanical and thermal mechanisms are responsible for hot forging tools damage such as wear,\\u000a thermal and mechanical fatigue. This work will be focused only on the mechanical fatigue life prediction for hot forging tools.\\u000a Both

Katia Mocellin; Matthieu Ferraro; Vincent Velay; Roland Logé; Farhad Rézaï-Aria

2009-01-01

185

Combining a neural network with a genetic algorithm for process parameter optimization  

Microsoft Academic Search

A neural-network model has been developed to predict the value of a critical strength parameter (internal bond) in a particleboard manufacturing process, based on process operating parameters and conditions. A genetic algorithm was then applied to the trained neural network model to determine the process parameter values that would result in desired levels of the strength parameter for given operating

D. F. Cook; C. T. Ragsdale; R. L. Major

2000-01-01

186

TRITIUM AGING EFFECTS ON THE FRACTURE TOUGHNESS PROPERTIES OF FORGED STAINLESS STEEL  

SciTech Connect

The fracture toughness properties of Type 21-6-9 stainless steel were measured for forgings in the unexposed, hydrogen-exposed, and tritium-exposed-and-aged conditions. Fracture toughness samples were cut from conventionally-forged and high-energy-rate-forged forward-extruded cylinders and mechanically tested at room temperature using ASTM fracture-toughness testing procedures. Some of the samples were exposed to either hydrogen or tritium gas (340 MPa, 623 K) prior to testing. Tritium-exposed samples were aged for up to seven years and tested periodically in order to measure the effect on fracture toughness of {sup 3}He from radioactive tritium decay. The results show that hydrogen-exposed and tritium-exposed samples had lower fracture- toughness values than unexposed samples and that fracture toughness decreased with increasing decay {sup 3}He content. Forged steels were more resistant to the embrittling effects of tritium and decay {sup 3}He than annealed steels, although their fracture-toughness properties depended on the degree of sensitization that occurred during processing. The fracture process was dominated by microvoid nucleation, growth and coalescence; however, the size and spacing of microvoids on the fracture surfaces were affected by hydrogen and tritium with the lowest-toughness samples having the smallest microvoids and finest spacing.

Morgan, M

2008-04-14

187

The Elements: Forged in Stars  

NSDL National Science Digital Library

All the stars in the universe, including the Sun, are nuclear furnaces fueled by fusion. Beginning with the fusion of hydrogen and continuing with fusion of successively heavier elements, stars form all the naturally occurring elements heavier than hydrogen and helium. This video segment illustrates the critical role that stars play in creating the elements, and describes the process of nucleosynthesis, in which increasingly heavier elements up through iron are formed, at which point the star collapses and explodes in a supernova, during which elements heavier than iron are created. The segment is three minutes forty-two seconds in length. A background essay and discussion questions are included.

188

76 FR 66996 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Forging...  

Federal Register 2010, 2011, 2012, 2013

...OMB Review; Comment Request; Forging Machines ACTION: Notice...request (ICR) titled, ``Forging Machines,'' to the Office of Management and...document periodic inspections of forging machines, guards, and...

2011-10-28

189

77 FR 23496 - Boundary Revision of Valley Forge National Historical Park  

Federal Register 2010, 2011, 2012, 2013

...4502-4025-720] Boundary Revision of Valley Forge National Historical Park AGENCY...the revision to the boundary of Valley Forge National Historical Park, pursuant...Number 464/108056, entitled ``Valley Forge National Historical Park...

2012-04-19

190

Analysis of process parameters of micro fluid-jet polishing on the processing effect  

NASA Astrophysics Data System (ADS)

Micro fluid-jet polishing technology is a new kind of ultra-smooth machining method which proposed on the basis of float polishing principle and combined with small tool polishing. This article will use micro jet ultra-smooth machine which developed by ourselves to develop the process experiment for plane elements. In the experiment, the material removal rate and surface roughness are taken as the assessment index, and the orthogonal experiment method is used to study the processing effect of different process parameters, such as the spindle speed, the pressure of the grinding head and the abrasive concentration. On the basis of the experimental results and combined with the micro jet polishing mechanism, the processing effect law of the various process parameters is analyzed. It shows that, the influence of polishing pressure and abrasive concentration on the removal efficiency is single, that is to say, the removal efficiency can be increased either by increasing the polishing pressure or by increasing the concentration of the slurry. However, the influence of the grinding speed on removal efficiency is not simple, the removal efficiency can be increased by increasing the grinding speed in the certain range, if continue to increase, the removal efficiency will decrease. The influence of the process parameters on the roughness is more complex, but it can be summarized grossly as follows: if the roughness is required to reduce quickly, the large polishing pressure and high concentration slurry can be chosen, but it has a large depth of removal; if the roughness is required to reduce and the removal depth is as small as possible, the little polishing pressure and the dilute polishing liquid can be chosen, but it has a long polishing time. So in the actual processing, the process parameters should be adjusted according to different machining needs, to finally reach the optimization.

Wang, Shaozhi; Liu, Jian; Zhang, Linghua

2013-08-01

191

Materials processing with supercritical antisolvent precipitation: process parameters and morphology of tartaric acid  

Microsoft Academic Search

Continuous precipitation with a compressed fluid antisolvent (PCA) has been used to produce fine particles of tartaric acid. Liquid solutions of tartaric acid in acetone, ethanol and methanol\\/ethanol mixtures have been sprayed into supercritical carbon dioxide used as antisolvent. Among the process parameters, pressure, temperature, flow rate of solvent and different nozzles have been tested. Furthermore, the effect of solute

H Kröber; U Teipel

2002-01-01

192

Historic Furnishings Report: Varnum's Quarters, Valley Forge National Historical Park, Valley Forge, Pennsylvania.  

National Technical Information Service (NTIS)

The primary interpretive objective at Varnum's Quarters is to show the impact of military occupation on the civilian countryside during the Valley Forge winter encampment of 1777-78. The house and property owned by David Stephens has long been identified ...

J. P. Brucksch

1993-01-01

193

A recuperative gas fired forge furnace  

SciTech Connect

To overcome the heat deficit and oxidizing atmosphere problems and to reduce fuel consumption, a small gas forge furnace has been developed which incorporates recuperative heating; as the combustion air is drawn into the furnace it is preheated by passing it through a simple heat exchanger which is heated by the exhaust gases from the furnace. This recuperative heating principle is the same used by blast and open hearth furnaces but they typically employ complex heat exchangers, and extensive blowers and valving to direct the flow of the intake and exhaust gases. In the furnace described in this article a chimney is provided at the rear of the furnace and the air intake ducts pass through the chimney before reaching the venturi where the fuel gas is injected. Thermocouples were place in the air intake ducts and the temperature of the recuperated air was 1000 F. Based on data in the Mechanical Engineers Handbook (Industrial Heating Furnaces) fuel savings are directly related to the temperature of the preheated air. The theoretical saving in fuel with 800 F. combustion air is about 19%. The furnace is very quiet, since no blowers are used and the venturi is located in the center of a long tube. To control the furnace atmosphere and to help reduce heat loss, a close fitting swing away door has been incorporated, and the entire furnace is insulated with lightweight high performance ceramic insulation. The resulting furnace easily achieves forge welding temperatures, has an oxygen depleted atmosphere and has proven to be very effective and capable for small machine and hand forging operations. 6 figs.

Gunter, R.; Schuler, K.W.; Ward, R.L.

1989-01-01

194

CAE for forging of titanium alloy aero-engine disc and integration with CAD–CAM for fabrication of the dies  

Microsoft Academic Search

Titanium alloy aero-engine turbine discs are subjected to stringent quality requirements pertaining to dimensional tolerances and mechanical properties. Therefore, the forging process of the disc is meticulously designed. This paper primarily deals with computer-aided engineering (CAE) of the die profile as well as the process design for the forging and in addition briefly addresses the integration of CAE with computer-aided

N Srinivasan; N Ramakrishnan; A Venugopal Rao; N Swamy

2002-01-01

195

Advanced rotor forgings for high-temperature steam turbines. Volume 2. Mechanical property evaluation. Final report. [CrMoV steels  

Microsoft Academic Search

Three advanced steel-melting processes - low-sulfur vacuum silicon deoxidation, electroslag remelting, and vacuum carbon deoxidation (VCD) - were applied to produce three CrMoV (ASTM A470, Class 8) steel forgings for steam turbine application. Ingots weighing about 100 t each were produced using these three processes, and rotors were forged with final weights of about 30 t each. Compared to the

V. P. Swaminathan; J. D. Landes

1986-01-01

196

Physics and Technological Training in Bulgarian Forge Craft  

NASA Astrophysics Data System (ADS)

The contemporary world regenerates and preserves the traditions of decorative-applied art and the national crafts. This brings up young generation and helps them to uncover the sources of national culture. In the commonly educational system the technological training realizes succession of new methods for national and applied art. The aim is examination of the national crafts as technological processes for cultivation of different metal constructions. There are enforced physical laws here. Seven basic groups of forging methods consider in Bulgarian tradition craft as heat treatment, plastic deformation and applying of different tensions. This gives information about morphology of construction after applying of stress, enlarging or decreasing of the linear sizes, structure change and the change of physical and mechanical properties.

Petkova, Petya N.; Velcheva, Keranka G.

2010-01-01

197

17. Forge building, fuel storage shed, and foundry, 1906 Photocopied ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. Forge building, fuel storage shed, and foundry, 1906 Photocopied from a photograph by Thomas S. Bronson, 'Group at Whitney Factory, 5 November 1906,' NHCHSL. The most reliable view of the fuel storage sheds and foundry, together with a view of the forge building. - Eli Whitney Armory, West of Whitney Avenue, Armory Street Vicinity, Hamden, New Haven County, CT

198

Precision forging technologies for magnesium alloy bracket and wheel  

Microsoft Academic Search

Fundamental investigations on precision forging technology of magnesium alloys were studied. As-cast billet prestraining and a new concept of hollow billet were proposed in order to reduce the maximum forming load. A scheme of isothermal forming and the use of combined female dies were adopted, which can improve the die filling capacity and ensure the manufacture of high quality forgings.

Qiang WANG; Zhi-min ZHANG; Xing ZHANG; Jian-min YU

2008-01-01

199

18. INTERIOR VIEW OF ROUGH FORGED TOOLS (FOREGROUND) WHICH ARE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. INTERIOR VIEW OF ROUGH FORGED TOOLS (FOREGROUND) WHICH ARE PRE-HEATED IN THE FURNACE (REAR RIGHT) AND THEN FORGED WITH THE BRADLEY HAMMER (LEFT) AS SHOWN BY JAMES GLASPELL - Warwood Tool Company, Foot of Nineteenth Street, Wheeling, Ohio County, WV

200

Refractory fiber as an insulation in the forging industry  

SciTech Connect

The use of refractory fiber as an insulating material in forge furnaces can be an important factor in achieving economy by reducing heat loss, heat storage, and fuel consumption per ton of product produced. Before discussing where and how refractory fiber linings are used in the forging industry, the evolution of this usage is in order.

Kyne, W.P.

1984-07-01

201

View west of small tooling and forging dies in Blacksmith ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View west of small tooling and forging dies in Blacksmith Shop, Boilermakers Department, east side of building 57; during World War II approximately forty women were employed as blacksmith's forging a variety of small tools; these may be the tools they used. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Structure Shop, League Island, Philadelphia, Philadelphia County, PA

202

Technical bases for precipitate hydrolysis process operating parameters  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for precipitate hydrolysis specified in WSRC-RP-92737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF).

Bannochie, C.J.

1992-10-05

203

Solar photo-Fenton treatment—Process parameters and process control  

Microsoft Academic Search

Photo-Fenton experiments were performed using alachlor as a model compound (initial concentration 100mg\\/L) in a compound parabolic collector solar pilot-plant. Three process parameters were varied following a central composite design without star points (temperature 20–50°C, iron concentration 2–20mg\\/L, illuminated volume 11.9–59.5% of total).Under all experimental conditions, complete alachlor degradation, mineralisation of chloride and 85–95% mineralisation of dissolved organic carbon (DOC)

W. Gernjak; M. Fuerhacker; P. Fernández-Ibañez; J. Blanco; S. Malato

2006-01-01

204

Processing Parameters Needed to Control Pathogens in Cold ...  

Center for Food Safety and Applied Nutrition (CFSAN)

... Please describe including temperature limits and parameters, how shipped, etc. ... the maximum storage temperature is 38°F. We ship via our own ... More results from www.fda.gov/food/foodscienceresearch/safepracticesforfoodprocesses

205

Technical bases for precipitate hydrolysis process operating parameters  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

Bannochie, C.J.; Lambert, D.P.

1992-11-09

206

Technical bases for precipitate hydrolysis process operating parameters. Revision 1  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

Bannochie, C.J.; Lambert, D.P.

1992-11-09

207

Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics  

SciTech Connect

The program explored a completely new, economical method of manufacturing nanocrystalline ceramics, Hot Superplastic Powder Forging (HSPF). The goal of the work was the development of nanocrystalline/low porosity optically transparent zirconia/alumina. The high optical transparency should result from lack of grain boundary scattering since grains will be smaller than one tenth the wavelength of light and from elimination of porosity. An important technological potential for this process is manufacturing of envelopes for high-pressure sodium vapor lamps. The technique for fabricating monolithic nanocrystalline material does not begin with powder whose particle diameter is <100 nm as is commonly done. Instead it begins with powder whose particle diameter is on the order of 10-100 microns but contains nanocrystalline crystallites <<100 nm. Spherical particles are quenched from a melt and heat treated to achieve the desired microstructure. Under a moderate pressure within a die or a mold at temperatures of 1100C to 1300C densification is by plastic flow of superplastic particles. A nanocrystalline microstructure results, though some features are greater than 100nm. It was found, for instance, that in the fully dense Al2O3-ZrO2 eutectic specimens that a bicontinuous microstructure exists containing <100 nm ZrO2 particles in a matrix of Al2O3 grains extending over 1-2 microns. Crystallization, growth, phase development and creep during hot pressing and forging were studied for several compositions and so provided some details on development of polycrystalline microstructure from heating quenched ceramics.

Cannon, W. Roger

2006-05-22

208

Application of the finite element method to predict material flow and defects in the semi-solid forging of A356 aluminum alloys  

Microsoft Academic Search

Research in the production of the semi-solid materials, process modeling and development of the constitutive flow behavior is required to assist the industrial application of Semi-Solid Forging (SSF) technology. This paper presents the results of the finite element simulations of semi-solid forging of A356 disks using DEFORM code. Although approximated flow stress curves of semi-solid A356 aluminum alloy were used,

Muammer Koç; Victor Vazquez; Thomas Witulski; Taylan Altan

1996-01-01

209

Forging of the AA6061\\/23 vol.%Al 2O 3p composite: Effects on microstructure and tensile properties  

Microsoft Academic Search

In this study, the influence of the forging process on microstructure, tensile resistance and fracture behaviour of the AA6061\\/Al2O3\\/23p composite is presented and discussed. Forging was carried out in an open die, at the temperature of 470°C, with a deformation ratio of 2.5:1 then the specimens were heat treated at the T6 condition. Microstructural characterization and density measurements showed that

L. Ceschini; G. Minak; A. Morri; F. Tarterini

2009-01-01

210

Research of the influence factors of the accumulator fast forging hydraulic control system  

Microsoft Academic Search

Accumulator is an important component of the fast forging hydraulic press system, and it has a great impact on the return precision and energy consumption of fast forging hydraulic machine, so do simulation and experiment study on the fast forging hydraulic system has a certain need for performance analysis. In this paper, we found the mathematical model of fast forging

Qian Ma; Xiangdong Kong; Jing Yao

2010-01-01

211

Estimation of physical parameters for dynamic processes with application to an industrial robot  

Microsoft Academic Search

The unknown parameters of physical laws which govern the dynamics of processes can be gained from measured input and output signals in a two step procedure. First the parameters of differential equations are estimated and then the physical parameters are calculated based on algebraic relations. After considering the model structures a suitable parameter estimation method for continuous time signals is

R. ISERMANN

1992-01-01

212

Influence of process parameters on stereolithography part shrinkage  

Microsoft Academic Search

Post-curing is one of the essential steps in the stereolithography (SL) process, as it affects the final dimensional accuracy of a rapid prototype produced by the SL method. The purpose of post-curing processes is to fully polymerize the uncured resin retained within the structure of the green-state prototype and hence, significantly improve its mechanical properties. However, under this process, the

W. L. Wang; C. M. Cheah; J. Y. H. Fuh; L. Lu

1996-01-01

213

Grain size modeling and optimization of rotary forged Alloy 718  

SciTech Connect

The study presented describes the simulation procedure and methodology used to develop two models for predicting recrystallized grain size in Alloy 718 billet. To simulate multiple pass forging of billet, controlled, high temperature compression testing was used to apply alternate deformation and dwell cycles to Alloy 718 specimens. Grain size obtained by simulation was found to be in excellent agreement with grain size from forged billet when cooling rate was included. The study also revealed that strain per pass and forging temperature were the predominant factors in controlling the recrystallized grain size. Both models were found to accurately predict the recrystallized grain size obtained by compression tests performed at super-solvus temperatures.

Domblesky, J.P. [Marquette Univ., Milwaukee, WI (United States); Shivpuri, R. [Ohio State Univ., Columbus, OH (United States)

1997-04-01

214

Computer simulation of the forging of fine grain IN718 alloy  

Microsoft Academic Search

In recent years, there has been great emphasis on the use of computer-aided tools in process design. The key to the success\\u000a of any computer modeling is the accurate knowledge of the mechanical and thermal properties of the various components of a\\u000a manufacturing system. In order to develop a data base of forging properties of the nickel-base alloy IN-718, isothermal

R. Srinivasan; V. Ramnarayan; U. Deshpande; V. Jain; I. Weiss

1993-01-01

215

Forming of hollow gear-shafts with pressure-assisted injection forging (PAIF)  

Microsoft Academic Search

Hollow gear-shafts were formed with a radial extrusion configuration, which involves the use of polymers as the pressurising media—pressure-assisted injection forging (PAIF). The process was qualified with definition of the forming-limit diagrams established with reference to three typical loading paths (histories of the injection and pressurisation). Forming was effected with the qualified procedures and pressurizing media. The results demonstrated feasibility

Yanling Ma; Yi Qin; Raj Balendra

2005-01-01

216

A new process based agglomeration parameter to characterize ceramic powders  

Microsoft Academic Search

Uranium dioxide powders are made through aqueous chemical route involving precipitation, drying, calcination and reduction. The presence of agglomerates causes powder packing difficulties in the compaction die, and non-uniform and incomplete densification on sintering. To quantify the degree of agglomeration, several authors have proposed ‘Agglomeration Parameters’. The change in BET specific surface area of calcined U3O8 upon reduction to UO2

Palanki Balakrishna; B. Narasimha Murty; M. Anuradha

2009-01-01

217

FEA Based Tool Life Quantity Estimation of Hot Forging Dies Under Cyclic Thermo-Mechanical Loads  

NASA Astrophysics Data System (ADS)

Hot forging dies are exposed during service to a combination of cyclic thermo-mechanical, tribological and chemical loads. Besides abrasive and adhesive wear on the die surface, fatigue crack initiation with subsequent fracture is one of the most frequent causes of failure. In order to extend the tool life, the finite element analysis (FEA) may serve as a means for process design and process optimisation. So far the FEA based estimation of the production cycles until initial cracking is limited as tool material behaviour due to repeated loading is not captured with the required accuracy. Material models which are able to account for cyclic effects are not verified for the fatigue life predictions of forging dies. Furthermore fatigue properties from strain controlled fatigue tests of relevant hot work steels are to date not available to allow for a close-to-reality fatigue life prediction. Two industrial forging processes, where clear fatigue crack initiation has been observed are considered for a fatigue analysis. For this purpose the relevant tool components are modelled with elasto-plastic material behaviour. The predicted sites, where crack initiation occurs, agree with the ones observed on the real die component.

Behrens, B.-A.; Bouguecha, A.; Schäfer, F.; Hadifi, T.

2011-01-01

218

Effect of some process parameters in enzymatic dyeing of wool.  

PubMed

This article reports on the dyeing of wool using an enzymatic system comprising laccase; dye precursor, 2,5-diaminobenzenesulfonic acid; and dye modifiers, catechol and resorcinol. Enzymatic dyeing was performed as a batchwise process at the temperature and pH of maximum enzyme activity. The effects of the process variables reaction time, enzyme, and modifier concentration on fabric color were studied, according to an appropriate experimental design. Different hues and depths of shades could be achieved by varying the concentration of the modifiers and the time of laccase treatment. The duration of the enzymatic reaction appeared to be the most important factor in the dyeing process. Thus, the dyeing process, performed at low temperature and mild pH, was advantageous in terms of reduced enzyme and chemical dosage. PMID:14566065

Tzanov, Tzanko; Silva, Carla Joana; Zille, Andrea; Oliveira, Jovita; Cavaco-Paulo, Artur

2003-10-01

219

Optimum process parameters for ultrasonic consolidation of 3003 aluminium  

Microsoft Academic Search

In this paper, the ultrasonic consolidation (UC) process is presented for the direct fabrication of monolithic aluminium tooling and components. UC is a solid-state process that involves the use of high frequency, low amplitude, mechanical vibrations to bond metal foils in a layer-by-layer method. The work, described in this paper, centres on the characterisation of aluminium 3003 foils that will

C. Y Kong; R. C Soar; P. M Dickens

2004-01-01

220

Texture Development During Equal Channel Angular Forging of BCC Metals  

SciTech Connect

Equal channel angular forging (ECAF) has been proposed as a severe plastic deformation technique for processing metals, alloys, and composites [e.g. Segal, 1995] (Fig. 1). The technique offers two capabilities of practical interest: a high degree of strain can be introduced with no change in the cross-sectional dimensions of the work-piece, hence, even greater strains can be introduced by re-inserting the work-piece for further deformation during subsequent passes through the ECAF die. Additionally, the deformation is accomplished by simple shear (like torsion of a short tube) on a plane whose orientation, with respect to prior deformations, can be controlled by varying the processing route. There is a nomenclature that has developed in the literature for the typical processing routes: A: no rotations; B{sub A}: 90 degrees CW (clockwise), 90 degrees CCW (counterclockwise), 9O degrees CW, 90 degrees CCW...; Bc: 90 degrees CW, 90 degrees CW, 90 degrees CW...; and C: 180 degrees, 18 0 degrees.... The impact of processing route on the subsequent microstructure [Ferasse, Segal, Hartwig and Goforth, 1997; Iwahashi, Horita, Nemoto and Langdon, 1996] and texture [Gibbs, Hartwig, Cornwell, Goforth and Payzant, 1998] has been the subject of numerous experimental studies.

Agnew, S.R.

1999-08-08

221

Signal processing for longitudinal parameters of the Tevatron beam  

SciTech Connect

We describe the system known as the Tevatron SBD [1] which is used to provide information on the longitudinal parameters of coalesced beam bunches in the Tevatron. The system has been upgraded over the past year with a new digitizer and improved software. The quantities provided for each proton and antiproton bunch include the intensity, the longitudinal bunch profile, the timing of the bunch with respect to the low-level RF, the momentum spread and the longitudinal emittance. The system is capable of 2 Hz operation and is run at 1 Hz.

Pordes, S.; Crisp, J.; Fellenz, B.; Flora, R.; Para, A.; Tollestrup, A.V.; /Fermilab

2005-05-01

222

Critical current densities in Bi-2223 sinter forgings.  

SciTech Connect

(Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) bars, prepared by sinter forging, exhibited good phase purity and strong textures with the c axes of the Bi-2223 grains parallel to the forging direction. The initial zero-field critical current density (J{sub c}) of the bars was 10{sup 3} A/cm{sup 2}, but because the forged bars were uncoated, this value decreased with repeated thermal cycling. J{sub c} as a function of applied magnetic field magnitude and direction roughly followed the dependencies exhibited by Ag-sheathed Bi-2223 tapes, but the forged bars were more strongly dependent on field strength and less strongly dependent on field angle.

Balachandran, U.; Fisher, B. L.; Goretta, K. C.; Harris, N. C.; Murayama, N.

1999-07-23

223

Valley Forge National Historical Park Annual Report, 2005.  

National Technical Information Service (NTIS)

In 2005, Valley Forge National Historical Park made strides in preserving historic buildings and reducing its maintenance backlog. With over 150 structures to manage, park staff frequently works with partners and other agencies to ensure that these histor...

2005-01-01

224

Quenching of aerospace forgings from high temperatures using air-assisted, atomized water sprays  

NASA Astrophysics Data System (ADS)

The nickel-based superalloy or titanium materials used in the aerospace industry are cooled from high temperatures during the heat treatment process to obtain appropriate strength properties. However, unacceptably high residual stresses can be developed in some situations if the rate of cooling is too high so that air-assisted, atomized water sprays have been suggested as an alternative to the widely used techniques of quenching in oil or water. Thus, this article examines two aspects of the use of air-water sprays for quenching aeroengine forgings. First, basic experimental heat transfer data are presented for a wide range of water flows and for surface temperatures up to approximately 850 °C, for both plane and recessed surfaces. Second, the heat transfer data are used in numerical simulations to study the influence of nonuniform spray distributions on the residual stress patterns in a typical forging.

de Oliveira, M.; Ward, J.; Garwood, D. R.; Wallis, R. A.

2002-02-01

225

Spray forming and subsequent forging of ?-titanium aluminide alloys  

Microsoft Academic Search

Spray forming experiments with a binary Ti–48.9Al (at.%) alloy and an advanced ?-TiAl alloy with the composition Ti–47Al–4(Nb, Mn, Cr, Si, B) (at.%), designated as ?-TAB, were carried out. Subsequently, the spray formed materials were forged. The sprayed and forged conditions were characterized in terms of microstructure, porosity, and impurity content. Tensile properties were evaluated at room and elevated temperatures.

Gerhard Wegmann; Rainer Gerling; Frank-Peter Schimansky; Jin-Xu Zhang

2002-01-01

226

Consolidation and Forging Methods for a Cryomilled Al Alloy  

Microsoft Academic Search

The method used to consolidate a cryogenically ball-milled powder is critical to the retention of superior strength along\\u000a with acceptable tensile ductility in the bulk product. In this study, gas-atomized Al 5083 powder was cryomilled, hot vacuum\\u000a degassed, and consolidated by hot isostatic pressing (HIP) or by quasi-isostatic (QI) forging to produce low-porosity billets.\\u000a The billets were then forged, either

A. P. Newbery; B. Ahn; R. W. Hayes; P. S. Pao; S. R. Nutt; E. J. Lavernia

2008-01-01

227

Consolidation and Forging Methods for a Cryomilled Al Alloy  

Microsoft Academic Search

The method used to consolidate a cryogenically ball-milled powder is critical to the retention of superior strength along with acceptable tensile ductility in the bulk product. In this study, gas-atomized Al 5083 powder was cryomilled, hot vacuum degassed, and consolidated by hot isostatic pressing (HIP) or by quasi-isostatic (QI) forging to produce low-porosity billets. The billets were then forged, either

A. P. Newbery; B. Ahn; R. W. Hayes; P. S. Pao; S. R. Nutt; E. J. Lavernia

2008-01-01

228

Reservoir and operational parameters influence in SAGD process  

Microsoft Academic Search

Thermal processes are used to improved heavy oil recovery, and they could be based on the steam injection, i.e. cyclic or continuous injection. The continuous injection has many variations, and has been studied both theoretically and experimentally (in pilot projects and in full field applications). One of the technologies that is being studied is one variation of the continuous injection,

J. L. M. Barillas; T DUTRAJR; W. Mata

2006-01-01

229

State and parameter estimations and their applications in process control  

Microsoft Academic Search

The increasingly more aggressive global competition for the production of higher-quality products at lower costs, along with a general trend away from new capital investments in the U.S., has placed considerable pressure on the process engineers to operate the existing plants more efficiently and to use the same plant for the production of many different products. The more efficient operation

Masoud Soroush

1998-01-01

230

Quenching and Cold-Work Residual Stresses in Aluminum Hand Forgings : Contour Method Measurement and FEM Prediction  

SciTech Connect

The cold-compression stress relief process used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings does not fully relieve the stresses. This study measured and predicted the residual stress in 7050-T74 (solution heat treated, quenched, and artificially overaged) and 7050-T7452 (cold compressed prior to aging) hand forgings. The manufacturing process was simulated by finite element analysis. First, a thermal analysis simulated the quench using appropriate thermal boundary conditions and temperature dependent material properties. Second, a structural analysis used the thermal history and a temperature and strain-rate dependent constitutive model to predict the stresses after quenching. Third, the structural analysis was continued to simulate the multiple cold compressions of the stress relief process. Experimentally, the residual stresses in the forgings were mapped using the contour method, which involved cutting the forgings using wire EDM and then measuring the contour of the cut surface using a CMM. Multiple cuts were used to map different stress components. The results show a spatially periodic variation of stresses that results from the periodic nature of the cold work stress relief process. The results compare favorably with the finite element prediction of the stresses.

Prime, M. B. (Michael B.); Newborn, M. A. (Mark A.); Balog, J. A. (John A.)

2003-01-01

231

Parameters affecting megasonic power transmittance in the megasonic cleaning process  

NASA Astrophysics Data System (ADS)

The presence of contaminants and particles on the surface has been long recognized as a cause of reduced wafer yields and delayed mask TAT. Especially, as the device pitch is continuously decreasing below submicron, the size of the contaminants and particles which must be controlled is decreasing below quarter-micron. It is believed that the megasonic process with the SC-1 chemical is the most important wet cleaning process in particle removal technology. The megasonic cleaning, which is dependent on the transmittance of megasonic power, is a commonly used technique for removing particles on the surface of a photomask. In this paper, in terms of both simulation and experiment, the transmittance of sound was obtained by varying the liquid temperature, the inclined angle, and the thickness of the bottom plate in the inner bath. Finally, after comparison of experimental results with simulation ones, we obtained the transmittance characteristics with similar tendency.

Kim, Yong H.; Park, Jin-Hong; Lee, Keumhee H.; Choi, Sung-Woon; Yoon, Hee-Sun; Sohn, Jung-Min

1998-09-01

232

Influence of process parameters in drawing of superconducting wire  

Microsoft Academic Search

Superconducting wire is often produced by the powder-in-tube method involving a number of different mechanical processes, among these is multi-step drawing operations of single filament wire. A silver tube is filled with ceramic powder (BiSrCaCuO). This composite is drawn in up to 100 steps, from an initial diameter of 20 mm to the final one of 1 mm. The present

M. Malberg; J. Bech; N. Bay; P. Skov-Hansen; G. Cualbu

1999-01-01

233

A stochastic process approach of the drake equation parameters  

NASA Astrophysics Data System (ADS)

The number N of detectable (i.e. communicating) extraterrestrial civilizations in the Milky Way galaxy is usually calculated by using the Drake equation. This equation was established in 1961 by Frank Drake and was the first step to quantifying the Search for ExtraTerrestrial Intelligence (SETI) field. Practically, this equation is rather a simple algebraic expression and its simplistic nature leaves it open to frequent re-expression. An additional problem of the Drake equation is the time-independence of its terms, which for example excludes the effects of the physico-chemical history of the galaxy. Recently, it has been demonstrated that the main shortcoming of the Drake equation is its lack of temporal structure, i.e., it fails to take into account various evolutionary processes. In particular, the Drake equation does not provides any error estimation about the measured quantity. Here, we propose a first treatment of these evolutionary aspects by constructing a simple stochastic process that will be able to provide both a temporal structure to the Drake equation (i.e. introduce time in the Drake formula in order to obtain something like N(t)) and a first standard error measure.

Glade, Nicolas; Ballet, Pascal; Bastien, Olivier

2012-04-01

234

Optimal adaptive filter realizations for sample stochastic processes with an unknown parameter  

Microsoft Academic Search

Techniques are given for realizing optimal learning systems for filtering a sampled stochastic process in the presence of an unknown constant or time-varying parameter. It is shown how the nonlinear Bayes optimal (quadratic sense) adaptive filters can be directly realized for continuous parameter spaces by real-time analog systems. Examples are given for both constant and time-varying unknown parameters.

C. Hilborn; D. Lainiotis

1969-01-01

235

Forging the future: the public health imperative.  

PubMed Central

During the 1980s, national policy promoted military expenditures and downsized domestic programs. These priorities, along with tax reform and deregulation, created a "domestic gulf crisis" with a new wave of vulnerable populations--poor children, the homeless, the elderly, and the uninsured. Our lack of a national health program compounds the problem. The 1990s will be a decade of change and challenge. To forge a healthier and stronger future for our nation, we must implement five public health imperatives: (1) We must have a national health program that is universal, comprehensive, and prevention-oriented, with built-in assurances for quality, efficiency, and a strong public health infrastructure. (2) We must have a comprehensive national health education and promotion program for all schoolchildren. (3) Women must have freedom of choice. (4) Prevention and public health must become one of our country's highest health priorities. (5) The federal government must increase its leadership, commitments, and resources to reach the goals set forth in Healthy Communities 2000 and Healthy People 2000.

Allukian, M

1993-01-01

236

Cavitation and failure during hot forging of Ti-6Al-4V  

SciTech Connect

The occurrence of cavity initiation and gross, free-surface fracture during subtransus hot pancake forging of Ti-6Al-4V with a transformed beta (colony) microstructure was established. Cavity initiation mechanisms were one of two distinct types. At temperatures approximately 75 C or more below the beta transus temperature (T{sub {beta}}), cavity initiation occurred at relatively low strains in the beta phase lying between the grain-boundary alpha phase and the lamellar colonies. By contrast, at temperatures near the transus (i.e., T {approx} T{sub {beta}} {minus} 25 C), cavity initiation occurred at much larger strains as a result of microfracture of partially-to-fully globularized alpha phase. Finite element method (FEM) modeling of the pancake forging process revealed that secondary tensile stresses were used to correlate both the cavity initiation and the gross free-surface fracture results to previous observations from uniaxial hot tension tests in which identical damage mechanisms had been observed. The tensile work criterion of Cockcroft and Latham (C + L) gave moderately good (quantitative) correlation between the forging and uniaxial tension behaviors. An alternate comparison based on the Rice and Tracey cavity growth model gave reasonable predictions of free-surface fracture but tended to overestimate the incidence of subsurface cavity initiation.

Semiatin, S.L. [Air Force Research Lab., Wright-Patterson AFB, OH (United States). Materials and Mfg. Directorate; Goetz, R.L.; Seetharaman, V. [UES, Inc., Dayton, OH (United States). Materials and Processes Div.; Shell, E.B. [Univ. of Dayton, OH (United States). Dept. of Chemical Engineering; Ghosh, A.K. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering

1999-05-01

237

Parameter identification and shape\\/process optimization in metal forming simulation  

Microsoft Academic Search

Nowadays, computer simulations of metal forming processes using the finite element method (FEM) have reached some level of maturity. The purpose of inverse problems is to determine the simulation input data for one or more of these forming processes, leading to a desired result. The first example is called parameter identification. This consists in evaluating the material parameters for material

Jean-Pascal Kleinermann; Jean-Philippe Ponthot

2003-01-01

238

The Application of Multi-layer Perception Networks in the Parameters Optimization of Stamping Forming Process  

Microsoft Academic Search

In the stamping process of high-strength steels, how to adjust each processing parameters to meet the needs of parts deformed is the key problem to be solved in the craft of stamping forming. The main work in this paper is to gain the optimum parameters by making use of neural network to fit experimental datum of stamping. In the experiment

Fengli Huang

2008-01-01

239

Effect of Processing Parameters on the Microstructures and Properties of Automobile Brake Drum  

Microsoft Academic Search

In this study, the effect of processing parameters such as alloy composition and shake-out time on the microstructure and subsequently the mechanical properties of brake drums to the specification of an automobile company had been studied. The results show that processing parameters such as alloy composition (Silicon and Carbon contents) affect the quantity and morphology of the carbides formed while

G. O. Oluwadare; P. O. Atanda

2007-01-01

240

Thermal analysis of laser surface transformation hardening—optimization of process parameters  

Microsoft Academic Search

This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P; laser beam diameter, Db; and the heat intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears

R. Komanduri; Z. B. Hou

2004-01-01

241

Color measurement of a solid active pharmaceutical ingredient as an aid to identifying key process parameters  

Microsoft Academic Search

The color of a powdered active pharmaceutical ingredient (API) in an investigational drug was found to be the result of a number of process parameters. Color measurements of the solid material were derived from reflectance data obtained from a sphere spectrophotometer. These data provided a convenient and non-destructive way to track the effects of variations to the process parameters on

Paul D. Oram; Jeffrey Strine

2006-01-01

242

Solar wind parameters determination based on statistical processing of the intershock experiment data  

Microsoft Academic Search

We discuss the methodology of evaluating solar wind kinetic parameters using statistical processing of data acquired from the multichannel plasma spectrometer BIFRAM (the INTERSHOCK Project). The great number of parameters to be evaluated and highly non-linear model represent the main difficulties. Several methods of data processing were developed; they are: algorithms of various accuracy and complexity that can be used

N. P. Belyaeva; L. S. Gurin; Yu. I. Yermolaev; G. N. Zastenker; E. E. Ryasanova

1989-01-01

243

Solar wind parameters determination based on statistical processing of the intershock experiment data  

Microsoft Academic Search

The methodology of evaluating solar wind kinetic parameters using statistical processing of data acquired from the multichannel plasma spectrometer BIFRAM (the INTERSHOCK Project) is described. The great number of parameters to be evaluated and the highly nonlinear model represent the main difficulties. Several methods of data processing were developed; they are: algorithms of various accuracy and complexity that can be

N. P. Beliaeva; L. S. Gurin; Yu. I. Yermolaev; G. N. Zastenker; E. E. Riazanova

1989-01-01

244

Evaluation of spherically invariant random process parameters as discriminators for speaker verification  

Microsoft Academic Search

In this work, we are interested in the potential use of spherically invariant random processes (SIRPs), described by two parameters, for speaker identification. These random processes have been shown to be a more statistically-accurate model for speech than Laplace and Gamma probability density functions. Computation of the two SIRP parameters is fast and simple and storage requirements are obviously small.

Joseph San Filippo; Phillip DeLeon

2004-01-01

245

Relationships Between Process Parameters, Microstructure, and Adhesion Strength of HVOF Sprayed IN718 Coatings  

NASA Astrophysics Data System (ADS)

Fundamental understanding of relationships between process parameters, particle in-flight characteristics, and adhesion strength of HVOF sprayed coatings is important to achieve the high coating adhesion that is needed in aeronautic repair applications. In this study, statistical Design of Experiments (DoE) was used to identify the most important process parameters that influence adhesion strength of IN718 coatings sprayed on IN718 substrates. Special attention was given to the parameters combustion ratio, total gas mass flow, stand-off distance and external cooling, since these parameters were assumed to have a significant influence on particle temperature and velocity. Relationships between these parameters and coating microstructure were evaluated to fundamentally understand the relationships between process parameters and adhesion strength.

Lyphout, Christophe; Nylén, Per; Östergren, Lars

2011-01-01

246

A hot compression testing apparatus for the study of isothermal forging  

NASA Astrophysics Data System (ADS)

An apparatus for uniaxial compression testing has been developed to simulate isothermal forging conditions. The system can apply 100-kN loads at temperatures up to 1200 + or - 3 C in a controlled environment and at constant true strain rates between 0.00001/s and 1/s. Results on the flow behavior of nickel-base superalloy compacts and composites are presented that demonstrate the importance of control of the testing parameters. The difference in flow strength of the two materials under identical testing conditions is discussed.

Immarigeon, J.-P. A.; Wallace, W.; Iandeil, A. Y.; de Malherbe, M. C.

1980-11-01

247

Advanced rotor forgings for high-temperature steam turbines. Volume 2. Mechanical property evaluation. Final report. [CrMoV steels  

SciTech Connect

Three advanced steel-melting processes - low-sulfur vacuum silicon deoxidation, electroslag remelting, and vacuum carbon deoxidation (VCD) - were applied to produce three CrMoV (ASTM A470, Class 8) steel forgings for steam turbine application. Ingots weighing about 100 t each were produced using these three processes, and rotors were forged with final weights of about 30 t each. Compared to the conventionally produced forgings, the advanced technology forgings show better tensile ductility and better uniformity along the radial and longitudinal directions. Charpy upper-shelf energy shows about 40% improvement, and no temper embrittlement was found using step-cooled and isothermal-aging treatments. Significant improvement in fracture toughness (K/sub IC/ and J/sub IC/) is realized for these forgings. Low-cycle fatigue life is better at high temperatures because of the absence of nonmetallic inclusions. Creep strength shows slight improvement. However, creep ductility is improved, probably because of low residual elements. The VCD forgings show excellent creep ductility, even with long lives. Both the toughness and creep properties are equal to or better than those of oil-quenched rotors produced by European practices. These improvements are attributed to cleaner steel, better control of ingot solidification, low residual elements (especially very low sulfur content), and the associated reduction of nonmetallic inclusions. These three rotors have been placed in service in three operating power plants in units rated at 520 MW each. Volume 1 of this report covers ingot and forging production, and volume 2 covers mechanical property evaluation. 40 refs., 84 figs., 15 tabs.

Swaminathan, V.P.; Landes, J.D.

1986-05-01

248

Parameter estimation for abrasive water jet machining process using neural networks  

Microsoft Academic Search

The abrasive water jet machining process, a material removal process, uses a high velocity jet of water and an abrasive particle\\u000a mixture. The estimation of appropriate values of the process parameters is an essential step toward an effective process performance.\\u000a This has led to the development of numerous mathematical and empirical models. However, the complexity of the process confines\\u000a the

Pratik J. Parikh; Sarah S. Lam

2009-01-01

249

40 CFR 467.40 - Applicability; description of the forging subcategory.  

Code of Federal Regulations, 2011 CFR

...467.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ALUMINUM FORMING POINT SOURCE CATEGORY Forging Subcategory § 467.40 Applicability; description of the forging...

2011-07-01

250

A PROCESS PARAMETERS DETERMINATION MODEL BY INTEGRATING ARTIFICIAL NEURAL NETWORK AND ANT COLONY OPTIMIZATION  

Microsoft Academic Search

In this paper, a methodology which integrates data mining (DM) and ant colony optimization (ACO) is proposed for process parameters determination of the chemical mechanical polishing (CMP) processes in semiconductor manufacturing. In the proposed method, an Artificial Neural Network (ANN) is first studied to realize the training process between inputs and outputs of network. However, due to the invisibility in

Chwen-Tzeng Su; Jui-Tsung Wong; Shang-Chun Tsou

2005-01-01

251

A system for unobtrusive in-car vital parameter acquisition and processing  

Microsoft Academic Search

In this contribution, a system for unobtrusive acquisition and processing of vital parameters using car-integrated sensors and processing devices is presented for the first time. The system consists of a steering wheel with integrated sensors, sensor processing and wireless communication interface and a portable monitoring unit for wireless data reception, display and interface to the car information system. A great

L. T. D'Angelo; J. Parlow; W. Spiesslt; S. Hocht; T. C. Lu?th

2010-01-01

252

Analysis of Leaf Parameters Measurement of Cucumber Based on Image Processing  

Microsoft Academic Search

This paper discusses image processing is carried on measuring cucumber leaf parameters. Leaf area of cucumber is determined with image processing, which results are compared with the results of grid counting, paper weighing and leaf area meter method. Leaf maximum length and leaf maximum width of cucumber are determined with image processing, which results are compared with the results of

You-wen Tian; Xiao-juan Wang

2009-01-01

253

Optimising process parameters for flip chip stencil printing using Taguchi's method  

Microsoft Academic Search

Solder paste printing is an important process in surface mount device assembly using the reflow soldering technique. There is wide agreement in the industry that the paste printing process accounts for the majority of assembly defects, and most defects originate from poor understanding of the effect of printing process parameters on printing performance and the nature of their interactions. The

D. Rajkumar; T. Nguty; N. N. Ekere

2000-01-01

254

Effects of Processing Parameters on the Forming Quality of C-Shaped Thermosetting Composite Laminates in Hot Diaphragm Forming Process  

NASA Astrophysics Data System (ADS)

In this study, the effects of processing temperature and vacuum applying rate on the forming quality of C-shaped carbon fiber reinforced epoxy resin matrix composite laminates during hot diaphragm forming process were investigated. C-shaped prepreg preforms were produced using a home-made hot diaphragm forming equipment. The thickness variations of the preforms and the manufacturing defects after diaphragm forming process, including fiber wrinkling and voids, were evaluated to understand the forming mechanism. Furthermore, both interlaminar slipping friction and compaction behavior of the prepreg stacks were experimentally analyzed for showing the importance of the processing parameters. In addition, autoclave processing was used to cure the C-shaped preforms to investigate the changes of the defects before and after cure process. The results show that the C-shaped prepreg preforms with good forming quality can be achieved through increasing processing temperature and reducing vacuum applying rate, which obviously promote prepreg interlaminar slipping process. The process temperature and forming rate in hot diaphragm forming process strongly influence prepreg interply frictional force, and the maximum interlaminar frictional force can be taken as a key parameter for processing parameter optimization. Autoclave process is effective in eliminating voids in the preforms and can alleviate fiber wrinkles to a certain extent.

Bian, X. X.; Gu, Y. Z.; Sun, J.; Li, M.; Liu, W. P.; Zhang, Z. G.

2013-10-01

255

An IRT Model with a Parameter-Driven Process for Change  

Microsoft Academic Search

An IRT model with a parameter-driven process for change is proposed. Quantitative differences between persons are taken into\\u000a account by a continuous latent variable, as in common IRT models. In addition, qualitative interindividual differences and\\u000a autodependencies are accounted for by assuming within-subject variability with respect to the parameters of the IRT model.\\u000a In particular, the parameters of the IRT model

Frank Rijmen; Paul De Boeck

2005-01-01

256

Statistical analysis of process parameters in drilling of AL\\/SIC P metal matrix composite  

Microsoft Academic Search

This paper presents a statistical analysis of process parameters for surface roughness in drilling of Al\\/SiCp metal matrix\\u000a composite. The experimental studies were conducted under varying spindle speed, feed rate, drill type, point angle of drill,\\u000a and heat treatment. The settings of drilling parameters were determined by using Taguchi experimental design method. The level\\u000a of importance of the drilling parameters

Gül Tosun

2011-01-01

257

Study on isothermal precision forging technology for a cylindrical aluminium-alloy housing  

Microsoft Academic Search

High-precision forging is becoming increasingly popular in modern plastic working. The effects of forging force, die chilling, residual stress and lubricant are significant in a hot precision forge. Producing aluminium-alloy precision forgings of reasonable complexity is a difficult operation. Temperature control within narrow ranges, high-accuracy dies and suitable forming methods are necessary in order to develop desirable microstructures, properties and

D. B Shan; Z Wang; Y Lu; K. M Xue

1997-01-01

258

Deformation characteristics of Ti6Al4V alloy under isothermal forging conditions  

Microsoft Academic Search

An investigation was undertaken to determine the influence of forge temperature, ram rate, and starting microstructure on\\u000a the deformation characteristics of isothermally forged Ti-6A1-4V alloy. Both yielding and finish forge pressures were measured\\u000a in the practical range of forge temperatures and ram rates. With the absence of die-chilling, the results obtained can be\\u000a quantitatively related to the hot deformation properties.

C. C. Chen; J. E. Coyne

1976-01-01

259

Optimizing Surface Roughness and Flank Wear on Hard Turning Process Using Taguchi Parameter Design  

Microsoft Academic Search

This paper presents an application of the Taguchi method parameter design to optimize the surface roughness, tool wear and cutting force by hard turning process. The Taguchi parameter design method is an efficient method in which response variable can be optimized, given various controls and using fewer experimental runs. Hard turning is the latest trend in all manufacturing industries and

S. Thamizhmanii; K. Kamarudin; E. A. Rahim; A. Saparudin; S. Hasan

2007-01-01

260

Determination of submerged arc welding process parameters using Taguchi method and regression analysis  

Microsoft Academic Search

This paper details the application of Taguchi technique and regression analysis to determine the optimal process parameters for submerged arc welding (SAW). The planned experiments are conducted in the semiautomatic submerged arc welding machine and the signal-to-noise ratios are computed to determine the optimum parameters. The percentage contribution of each factor is validated by analysis of variance (ANOVA) technique. Multiple

S Kumanan; J Edwin; Raja Dhas; K Gowthaman

2007-01-01

261

MODEL PARAMETERS FOR AGRICULTURAL SYSTEMS WITH NONLINEAR PROCESS INTERATIONS AND SPATIAL VARIABILITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Models and model spatial units are applied at different scales, often without explicitly adjusting parameter values. Scale-dependence in model parameters usually results from heterogeneity in the underlying properties below the scale of application. Thus, it is important to recognize process and dim...

262

A mathematical model for the joint determination of optimal process and sampling plan parameters  

Microsoft Academic Search

Purpose – The purpose of this paper is to integrate the decisions regarding optimal process mean and the parameters of a sampling plan. Design\\/methodology\\/approach – A model is developed to determine these parameters. The model maximizes producer expected profit, while protecting the consumer through a constraint on the probability of accepting lots with low incoming quality. The model is presented

M. A. Darwish; S. O. Duffuaa

2010-01-01

263

Relating statistical MOSFET model parameter variabilities to IC manufacturing process fluctuations enabling realistic worst case design  

Microsoft Academic Search

The implementation of a viable statistical circuit design methodology requiring detailed knowledge of the variabilities of, and correlations among, the circuit simulator model parameters utilized by designers, and the determination of the important relationships between these CAD model parameter variabilities and the process variabilities causing them is presented. This work addresses the above requirements by detailing a new framework which

James A. Power; Brian Donnellan; Alan Mathewson

1994-01-01

264

Numerical self-regulation of time-dependent parameters in tube hydroforming processes  

NASA Astrophysics Data System (ADS)

Large expansion in tube hydroforming processes is only achievable with proper combination of inner pressure and axial compression applied on the tube. To avoid bursting in T-branches additional radial force controlled punches are necessary. A suboptimal layout of the corresponding time-dependent parameters results in wrinkling or ruptures. Successful tube hydroforming processes demand optimization of the pressure-time diagram as well as the prescribed displacement or force schedules of the forming tools, which is by no means an easy task. Most current processes are based on the trial and error method and are usually influenced by some random factors. A new algorithm to automatically optimize the process parameters in the tube hydroforming processes is presented in this work. This algorithm combines the FEM process calculation with the parameter determination according to the basic physical principles. The coupled PID-control is established.

Holecek, M.; Hora, P.

2005-08-01

265

Statistical optimization of process parameters for landfill leachate treatment using electro-Fenton technique  

Microsoft Academic Search

Mature landfill leachate is typically non-biodegradable and contains high concentration of refractory organics. The aim of this research was to optimize operating parameters in electro-Fenton process, for the removal of recalcitrant organics from semi-aerobic landfill leachate using response surface methodology (RSM). Effectiveness of important process parameters H2O2\\/Fe2+ molar ratio, current density, pH and reaction time were determined, optimized and modeled

Soraya Mohajeri; Hamidi Abdul Aziz; Mohamed Hasnain Isa; Mohammad Ali Zahed; Mohd. Nordin Adlan

2010-01-01

266

A novel separation process for olefin gas purification: Effect of operating parameters on separation performance and process optimization  

Microsoft Academic Search

Separation of propylene–propane mixtures using facilitated transport membrane is potentially a novel separation process for olefin gas purification. The main purpose of this study was to find optimum values of the process parameters using the Taguchi approach. The Taguchi method was selected as the statistical technique since it allows the main effects to be estimated with a minimum number of

Maryam Takht Ravanchi; Tahereh Kaghazchi; Ali Kargari; Mansoureh Soleimani

2009-01-01

267

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti6Al4V powder compacts  

Microsoft Academic Search

The effect of isothermal hot forging (IHF) on microstructure, pore closure, and tensile and fatigue properties of Ti-6A1-4V\\u000a blended elemental cold pressed and sintered powder compacts was investigated. Two types of sponge fines were used: (a) high\\u000a chloride produced by the Hunter sodium reduction process (HP) and (b) low chloride produced by the electrolytic process (EP).\\u000a The as-sintered HP compacts

I. Weiss; D. Eylon; M. W. Toaz; F. H. Froes

1986-01-01

268

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti6Al4V powder compacts  

Microsoft Academic Search

The effect of isothermal hot forging (IHF) on microstructure, pore closure, and tensile and fatigue properties of Ti-6A1-4V blended elemental cold pressed and sintered powder compacts was investigated. Two types of sponge fines were used: (a) high chloride produced by the Hunter sodium reduction process (HP) and (b) low chloride produced by the electrolytic process (EP). The as-sintered HP compacts

I. Weiss; D. Eylon; M. W. Toaz; F. H. Froes

1986-01-01

269

76 FR 30200 - Forging Machines; Extension of the Office of Management and Budget's (OMB) Approval of...  

Federal Register 2010, 2011, 2012, 2013

...Docket No. OSHA-2011-0064] Forging Machines; Extension of the Office of Management...requirements contained in the Forging Machines Standard (29 CFR 1910.218). The...serious injury by ensuring that forging machines used by them are in safe operating...

2011-05-24

270

Advanced simulations for hot forging: heat transfer model for use with the finite element method  

Microsoft Academic Search

In a companion paper, a friction model for isothermal forging is described. Extension to a general hot forging case requires consideration of heat transfer across the tooling\\/workpiece interface, since a chilling of the workpiece by the dies will have evolving material properties that can significantly affect the forging operation. This is a complicated problem, since the film thickness, surface roughness

William R. D. Wilson; Steven R. Schmid; Jiying Liu

2004-01-01

271

Optimization of a Cu CMP process modeling parameters of nanometer integrated circuits  

NASA Astrophysics Data System (ADS)

A copper chemical mechanical polishing (Cu CMP) process is reviewed and analyzed from the view of chemical physics. Three steps Cu CMP process modeling is set up based on the actual process of manufacturing and pattern-density-step-height (PDSH) modeling from MIT. To catch the pattern dependency, a 65 nm testing chip is designed and processed in the foundry. Following the model parameter extraction procedure, the model parameters are extracted and verified by testing data from the 65 nm testing chip. A comparison of results between the model predictions and test data show that the former has the same trend as the latter and the largest deviation is less than 5 nm. Third party testing data gives further evidence to support the great performance of model parameter optimization. Since precise CMP process modeling is used for the design of manufacturability (DFM) checks, critical hotspots are displayed and eliminated, which will assure good yield and production capacity of IC.

Wenbiao, Ruan; Lan, Chen; Tianyu, Ma; Jingjing, Fang; He, Zhang; Tianchun, Ye

2012-08-01

272

Effect of process parameters on abnormal grain growth during friction stir processing of a cast Al alloy  

Microsoft Academic Search

The effects of process parameters and friction stir processing (FSP) run configurations on the stability of nugget microstructure at elevated temperatures were evaluated. Cast plates of an Al–7Si–0.6Mg alloy were friction stir processed using a combination of tool rotation rates and tool traverse speeds. All single pass runs showed some extent of abnormal grain growth (AGG), whereas multi-pass runs were

Saumyadeep Jana; Rajiv S. Mishra; John A. Baumann; Glenn J. Grant

2010-01-01

273

Project on National Security Reform: Forging a New Shield.  

National Technical Information Service (NTIS)

Forging a New Shield represents the culmination of more than two years of work by more than three hundred dedicated U.S. national security executives, professionals, and scholars. It provides a comprehensive historical analysis of the current U.S. nationa...

2008-01-01

274

Family Health and Financial Literacy--Forging the Connection  

ERIC Educational Resources Information Center

|Families are at-risk of or experiencing a diminished quality of living and life in current economic times and difficult decisions are required. Health and financial literacy are the basis for wise personal and public decision making. Family and consumer sciences (FCS) professionals can forge connections between health and financial literacy to…

Braun, Bonnie; Kim, Jinhee; Anderson, Elaine A.

2009-01-01

275

The Valley Forge Encampment: Epic on the Schuylkill.  

ERIC Educational Resources Information Center

Valley Forge, outside Philadelphia (Pennsylvania), has long been recognized as the site of a great victory of the human spirit. Eleven thousand men including Blacks and Indians resided there during the winter of 1777-78 and triumphed over cold, starvation, nakedness, disease, and uncertainty. The encampment site was unprepared for the tattered,…

Trussell, John B. B., Jr.

276

Recent developments in forged railroad wheels for improved performance  

Microsoft Academic Search

The service environment for North American railroad wheels is more demanding than ever due to higher freight car gross rail load (GRL), greater locomotive horsepower, more efficient equipment utilization and faster train speeds. Wheel manufacturers are therefore working diligently to improve product quality and in service product performance. This paper describes various efforts by a forged railroad wheel manufacturer to

C. Lonsdale; Steven Dedmon; J. Pilch

2005-01-01

277

Forging New Global Alliances: Emerging Markets and Advanced Economies  

Microsoft Academic Search

Forging new global alliances or new legal and institutional frameworks through international cooperation could help solve the 2007–2009 financial crisis by addressing the most vulnerable aspects of the current financial system and infrastructure. These aspects are liquidity, which is at the heart of the stability of the financial system; trust and transparency, with better disclosure of banks’ institutional arrangements for

Ceslav Ciobanu; David Bejou

2009-01-01

278

Forging Consensus for Implementing Youth Socialization Policy in Northwest China  

ERIC Educational Resources Information Center

|The goal of this article is to examine how the provincial education media in China play a role of forging consensus among local actors responsible for the implementation of new centrally-promulgated youth socialization policy. In doing so, it also explores the tension among three of the Chinese state's claims to legitimacy: economic development,…

Fairbrother, Gregory P.

2011-01-01

279

Prediction of Microstructure in High-Strength Ductile Forging Parts  

Microsoft Academic Search

Governmental, environmental and economic demands call for lighter, stiffer and at the same time cheaper products in the vehicle industry. Especially safety relevant parts have to be stiff and at the same time ductile. The strategy of this project was to improve the mechanical properties of forging steel alloys by employing a high-strength and ductile bainitic microstructure in the parts

M. Urban; C. Keul; A. Back; W. Bleck; G. Hirt

2010-01-01

280

The Valley Forge Encampment: Epic on the Schuylkill.  

ERIC Educational Resources Information Center

|Valley Forge, outside Philadelphia (Pennsylvania), has long been recognized as the site of a great victory of the human spirit. Eleven thousand men including Blacks and Indians resided there during the winter of 1777-78 and triumphed over cold, starvation, nakedness, disease, and uncertainty. The encampment site was unprepared for the tattered,…

Trussell, John B. B., Jr.

281

Evaluation of Die Forging of Ductile Cast Iron.  

National Technical Information Service (NTIS)

The report describes tests of the forgeability of ductile cast iron in the 1,700 to 1,950 range. It was found that while scaling is minimal, ductile iron is less plastic and requires more time and force for a given reduction than does steel forged at the ...

J. W. Spretnak D. E. Tilton S. Eliot S. J. Kiefer R. T. Herdegen

1977-01-01

282

Family Health and Financial Literacy--Forging the Connection  

ERIC Educational Resources Information Center

Families are at-risk of or experiencing a diminished quality of living and life in current economic times and difficult decisions are required. Health and financial literacy are the basis for wise personal and public decision making. Family and consumer sciences (FCS) professionals can forge connections between health and financial literacy to…

Braun, Bonnie; Kim, Jinhee; Anderson, Elaine A.

2009-01-01

283

Forging Consensus for Implementing Youth Socialization Policy in Northwest China  

ERIC Educational Resources Information Center

The goal of this article is to examine how the provincial education media in China play a role of forging consensus among local actors responsible for the implementation of new centrally-promulgated youth socialization policy. In doing so, it also explores the tension among three of the Chinese state's claims to legitimacy: economic development,…

Fairbrother, Gregory P.

2011-01-01

284

Caracterisation de l'Alliage 6242 Si: Rouet Centrifuge en Forgeage Conventionnel (Characterization of the 6242 Si Alloy. Centrifugal Wheel in Conventional Forging).  

National Technical Information Service (NTIS)

The analysis of two Ti alloy specimens are a reference for the optimization of the thermomechanical processing for a category of isothermal forging. The thermal processing includes solution treatment at 995 C or 980 C with 2 hr air cooling. It is found th...

1989-01-01

285

THE RESEARCH OF TECHNOLOGICAL PARAMETERS INFLUENCE ON THE PROCESS OF NITINOL FABRICATION AND PLASTIC DEFORMATION  

Microsoft Academic Search

Titanium and nickel alloy, with 48 - 55 at. % Ni (rest Ti), named Nitinol has property of thermal and mechanical memory and its properties and application depends strongly on a fabrication processes. Nitinol was produced in semi-industrial conditions. Testing results of the quality of the obtained alloy are related to technological parameters of the production and processing. The aim

D. ?ubela

2006-01-01

286

Influence of Cell Support and Operating Parameters on the Competitiveness of High-Temperature Electrolysis Process  

Microsoft Academic Search

This work focuses on hydrogen production by high-temperature electrolysis and the influence of operating parameters for cathode- or electrolyte-supported cells, used to build the electrolyzer, on the process competitiveness. The rigorous modeling of the electrical and thermal behavior of planar cells was performed and integrated into our program to estimate the hydrogen production cost, accounting process investment, and operation costs.

R. Rivera-Tinoco; C. Bouallou

2010-01-01

287

Process parameter influence on performance of friction taper stud welds in AISI 4140 steel  

Microsoft Academic Search

Friction taper stud welding is a new variant of friction welding which has been developed from the principles of friction hydro-pillar processing. This paper considers the effect of weld process parameters on weld defects, macrostructure and mechanical properties in AISI 4140 steel. It also presents 3D residual stress data for a typical friction taper stud weld. Applied downwards force, rotational

D. G. Hattingh; D. L. H. Bulbring; A. Els-Botes; M. N. James

2011-01-01

288

Influence of process parameters on fluidity of investment-cast AZ91D magnesium alloy  

Microsoft Academic Search

Investment casting is a versatile and precise process, which allows the fabrication of components requiring intricate shapes, the filling of thin sections and the reproduction of fine details. It is also useful for casting magnesium alloy prototypes but little quantitative information is available about the relationships between process parameters and fluidity, which plays an important role in the successful production

S. Lun Sin; D. Dubé

2004-01-01

289

Optimisation of Shape Parameters and Process Manufacturing for an Automotive Safety Part  

Microsoft Academic Search

In recent years, the weight and the cost of automotive vehicles have considerably increased due to the importance devoted to safety systems. It is therefore necessary to reduce the weight and the production cost of components by improving their shape and manufacturing process. This work deals with a numerical approach for optimizing the manufacturing process parameters of a safety belt

Eric Gildemyn; Philippe Dal Santo; Alain Potiron; Delphine Saïdane

2007-01-01

290

State and parameter estimation via minimum distortion filtering with application to Chemical Process Control  

Microsoft Academic Search

State and parameter estimation are cornerstone problems in Chemical Process Control. When the problem is linear and gaussian, the celebrated Kalman Filter provides a simple and elegant solution to the recursive filtering problem. However, many practical systems (including most Chemical Processes) are nonlinear. In this case, the Kalman Filter cannot be directly applied and other methods are necessary. In this

Graham C. Goodwin; Mauricio G. Cea

2011-01-01

291

Solar wind parameters determination based on statistical processing of the intershock experiment data  

NASA Astrophysics Data System (ADS)

The methodology of evaluating solar wind kinetic parameters using statistical processing of data acquired from the multichannel plasma spectrometer BIFRAM (the INTERSHOCK Project) is described. The great number of parameters to be evaluated and the highly nonlinear model represent the main difficulties. Several methods of data processing were developed; they are: algorithms of various accuracy and complexity that can be used for calculating detector responses, various criteria of minimization and their combination, ways to select initial approximation, and methods of searching for a global minimum. The results of processing solar wind data measured with high time resolution in the vicinity of the earth's bow shock crossing illustrate the proposed methodology.

Beliaeva, N. P.; Gurin, L. S.; Yermolaev, Yu. I.; Zastenker, G. N.; Riazanova, E. E.

292

Wavelet theory and belt finishing process, influence of wavelet shape on the surface roughness parameter values  

NASA Astrophysics Data System (ADS)

This article presents a multi-scale theory based on wavelet decomposition to characterize the evolution of roughness in relation with a finishing process or an observed surface property. To verify this approach in production conditions, analyses were developed for the finishing process of the hardened steel by abrasive belts. These conditions are described by seven parameters considered in the Tagushi experimental design. The main objective of this work is to identify the most relevant roughness parameter and characteristic length allowing to assess the influence of finishing process, and to test the relevance of the measurement scale. Results show that wavelet approach allows finding this scale.

khawaja, Z.; Guillemot, G.; Mazeran, P.-E.; El Mansori, M.; Bigerelle, M.

2011-08-01

293

Multi-Response Optimization of Process Parameters for Low-Pressure Cold Spray Coating Process Using Taguchi and Utility Concept  

NASA Astrophysics Data System (ADS)

Most of the existing multi-response optimization approaches focus on the subjective and practical know-how of the process. As a result, some confusion and uncertainty are introduced in the overall decision-making process. In this work, an approach based on a Utility theory and Taguchi quality loss function has been applied to the process parameters for low-pressure cold spray process deposition of copper coatings, for simultaneous optimization of more than one response characteristics. In the present paper, two potential response parameters, i.e., coating thickness and coating density, have been selected. Utility values based on these response parameters have been analyzed for optimization using the Taguchi approach. The selected input parameters of powder feeding arrangement, substrate material, air stagnation pressure, air stagnation temperature, and stand-off distance significantly improve the Utility function (raw data) comprising quality characteristics (coating thickness and coating density). The percentage contribution of the parameters to achieve a higher value of Utility function is substrate material (50.03%), stand-off distance (28.87%), air stagnation pressure (6.41%), powder feeding arrangement (4.68%), and air stagnation temperature (2.64%).

Goyal, Tarun; Sidhu, T. S.; Walia, R. S.

2013-09-01

294

Nonadherence to the isochrony principle in forged signatures.  

PubMed

Highly programmed skilled movements are executed in such a way that their kinematic features adhere to certain rules referred to as minimization principles. One such principle is the isochrony principle, which states that the duration of voluntary movement remains approximately constant across a range of movement distances; that is, movement duration is independent of movement extent. The concept of isochrony suggests that some information stored in the motor program is constant, thus reducing the storage demands of the program. The aim of the present study was to examine whether forged signatures can be distinguished from genuine signatures on the basis of isochrony kinematics. Sixty writers were asked to write their own signatures and to forge model signatures representing three different writing styles: text-based, stylized, and mixed. All signatures were digitized to enable high precision dynamic analyses of stroke kinematics. Vertical stroke duration and absolute amplitude were measured for each pen stroke of the signatures using MovAlyzeR(®) software. Slope coefficients derived from simple regression models of the relationship between stroke duration and amplitude served as our measure of isochrony. The slope coefficient reflects the degree to which stroke duration increases in relation to stroke amplitude. Higher coefficients indicate greater increases in stroke duration for a given stroke amplitude and thus violate the isochrony principle. We hypothesized that the duration-amplitude coefficients for forged signatures would be significantly greater than for genuine signatures suggesting non-adherence to the isochrony principle. Results indicated that regardless of the style of the writer, genuine signatures were associated with low slope coefficients Pen strokes forming forged signatures had significantly greater duration-amplitude slope coefficients than genuine signatures. These findings suggest that when forging signatures, writers execute pen movements having steeper duration-amplitude relationships than for genuine signatures. PMID:23084659

Caligiuri, Michael P; Mohammed, Linton A; Found, Bryan; Rogers, Doug

2012-10-18

295

3D FEM analysis of basic process parameters in rotary piercing mill  

Microsoft Academic Search

In this paper the 3D FEM analysis of basic process parameters in rotary piercing mill is presented. In this process the material\\u000a is formed by means of two skew rolls, two Diescher’s discs and a plug. The material is dragged by the rolls, it moves axially\\u000a forward and rotates. The FEM analyze of the rotary piercing process was made under

Jan Kazanecki; Zbigniew Pater; Jaroslaw Bartnicki

296

Parameter optimization of wire electric discharge machining process using GA and PSO  

Microsoft Academic Search

Wire Electric Discharge Machining (WEDM) is one of the important non-traditional machining processes for machining of intricate profiles in conductive and difficult to machine materials. The machining performance of this process largely depends on various process parameters, such as applied voltage, ignition pulse current, pulse-off time, pulse duration, serve controlled reference mean voltage, servo-speed variation, wire speed, wire tension and

Pandu R. Vundavilli; J. Phani Kumar; Ch. Sai Priyatham

2012-01-01

297

On selecting a prior for the precision parameter of Dirichlet process mixture models  

USGS Publications Warehouse

In hierarchical mixture models the Dirichlet process is used to specify latent patterns of heterogeneity, particularly when the distribution of latent parameters is thought to be clustered (multimodal). The parameters of a Dirichlet process include a precision parameter ?? and a base probability measure G0. In problems where ?? is unknown and must be estimated, inferences about the level of clustering can be sensitive to the choice of prior assumed for ??. In this paper an approach is developed for computing a prior for the precision parameter ?? that can be used in the presence or absence of prior information about the level of clustering. This approach is illustrated in an analysis of counts of stream fishes. The results of this fully Bayesian analysis are compared with an empirical Bayes analysis of the same data and with a Bayesian analysis based on an alternative commonly used prior.

Dorazio, R. M.

2009-01-01

298

Approach for long term environmental parameters monitoring process using data acquisition devices and high level applications for data processing  

NASA Astrophysics Data System (ADS)

Present paper describes a long term monitoring process of few environmental parameters for evaluating green energy potential (wind energy and solar energy) of a small geographical area (~ 32 km2). The monitoring approach presented in this paper consists in: real-time data acquisition process using two real-time data acquisition devices (DAQ); a wireless network used for long distance data transmission in order to send all acquired data to a remote location for processing; Virtual Instrument (VI's) applications used for controlling data acquisition devices and the acquisition process; a network protocol analyzer used for a detailed analysis of the communication protocols and data packets; the management of the huge volume of sensor data by using a high level software application; long term sensor monitoring using a complex graphic software application. The measured environment parameters are the following: wind speed, wind direction, temperature, sun intensity and illumination, steel pylon vibrations on three axes.

Croitoru, Bogdan; Boca, Loredana; Abrudean, Mihail; Joldes, Remus

2010-09-01

299

Methylene-blue sensitized dichromated gelatin holograms: a study of optimum coating and processing parameters  

NASA Astrophysics Data System (ADS)

The optimum conditions for preparing, recording and processing of Methylene-Blue Sensitized Dichromated Gelatin depend on some atmospheric parameters of laboratory where the operations are carried-out and the optimum value of different parameters appropriate to different conditions must be determined by experiment. Int his paper these conditions as well as the quality control of DCG plates and the diffraction efficiency of holographic gratings registered on these plates are reported.

Madjidi-Zolbanine, Habib; Shabestari, N. P.; Karimi, R.

1996-09-01

300

The effect of processing parameters on the propensity for central fracturing in piercing  

Microsoft Academic Search

Successful competition in the seamless tubular products market demands improvements in surface and dimensional quality in\\u000a products from seamless pipe mills. It is reported that pass design, piercer setup and operating parameters have critical effects\\u000a on both dimensional and surface quality. Defects which form during the piercing process are the result of these mechanical\\u000a parameters (which control the localized stress

Emin Erman

1987-01-01

301

On Effect of Material Parameters Used in Numerical Simulation of Forming Processes  

NASA Astrophysics Data System (ADS)

This paper introduces a new methodology from which better material parameters may be identified. The method will account for both non-repeatability of test data (by means of signal-to-noise weighting factors) and potential discrepancies between material parameters in different deformation modes (by means of a multi-objective optimization process). Finally, to show the application of the method, test data for a 2×2 twill weave fabric from different modes (namely, uniaxial extension and bias-extension) are selected to identify the model parameters of an orthotropic material model. The procedure may be applied to other material models and applications.

Milani, A. S.; Nemes, J. A.

2004-06-01

302

TECHNICAL NOTE: Adhesive bonding of microfluidic chips: influence of process parameters  

NASA Astrophysics Data System (ADS)

In this note, the influence of process parameters for adhesive bonding as a versatile approach for the sealing of polymer microfluidic chips is investigated. Specifically, a process chain comprising pre-processing, adhesive transfer as well as post-processing is presented and parameter recommendations are provided. As a device for adhesive transfer, a modified laminator is utilized which transfers thin layers of adhesive onto the chip surface, only via a silicone roll. Using this device and a high temperature (Tg > 100 °C) epoxy adhesive, adhesive layers in the range of 2-4 µm can be reproducibly transferred (CV < 4%). For best bonding results, it is recommended to provide 2.5 µm thin layers of adhesive in combination with a subsequent evacuation step at 10 mbar for 3 h. Further, it is proposed to integrate capture channels near large, featureless areas to compensate for variations in processing and thus prevent clogging of channels.

Riegger, Lutz; Strohmeier, Oliver; Faltin, Bernd; Zengerle, Roland; Koltay, Peter

2010-08-01

303

Digital signal processing algorithms for power and line parameter measurements with low sensitivity to frequency change  

SciTech Connect

This paper introduces a new approach to definition of digital signal processing algorithms using bilinear form representation. The new algorithms are used to calculate power and line parameter values based on the current and voltage samples. The bilinear form approach provides a convenient methodology for optimal design of digital signal processing algorithms. This feature is utilized to design digital algorithms for power and line parameter measurements with low sensitivity to system frequency change. Several different algorithms are defined and their performance to system frequency change. Various sampling rates and different data windows are utilized to define several test cases.

Perunicic, B.; Levi, S. (Sarajevo Univ. (Yugoslavia)); Kezunovic, M.; Soljanin, E. (Texas A and M Univ., College Station, TX (USA))

1990-04-01

304

Optimisation of Shape Parameters and Process Manufacturing for an Automotive Safety Part  

NASA Astrophysics Data System (ADS)

In recent years, the weight and the cost of automotive vehicles have considerably increased due to the importance devoted to safety systems. It is therefore necessary to reduce the weight and the production cost of components by improving their shape and manufacturing process. This work deals with a numerical approach for optimizing the manufacturing process parameters of a safety belt anchor using a genetic algorithm (NSGA II). This type of component is typically manufactured in three stages: blanking, rounding of the edges by punching and finally, bending with a 90° angle. In this study, only the rounding and the bending will be treated. The numerical model is linked to the genetic algorithm in order to optimize the process parameters. This is implemented by using ABAQUS© script files developed in the Python programming language. The algorithm modifies the script files and restarts the FEM analysis automatically. Lemaitre's damage model is introduced in the material behaviour laws and implemented in the FEM analysis by using a FORTRAN subroutine. The influence of two process parameters (die radius and the rounding punch radius) and five shape parameters were investigated. The objective functions are (i) the material damage state at the end of the forming process, (ii) the stress field and (iii) the maximum Von Mises stress in the folded zone.

Gildemyn, Eric; Dal Santo, Philippe; Potiron, Alain; Saïdane, Delphine

2007-05-01

305

Study on Surface Durability of Powder-Forged Rollers with Case-Hardening  

NASA Astrophysics Data System (ADS)

Powder forging (P/F), which combines powder metallurgy (P/M) and forging technologies, leads to refined poreless microstructure in the material. Therefore, the mechanical property of the P/F material can be greatly improved comparing with that of the sintered material. In this paper, the rolling contact fatigue tests were conducted using a two-cylinder testing machine, and the surface failure and durability of the case-hardened P/F rollers were compared with those of the case-hardened conventional steel rollers. From the experimental and analytical results, it could be concluded that the failure mode of the P/F and the steel rollers was mainly spalling, and the surface durability of the P/F rollers was almost the same as that of the steel rollers. Evaluating the rolling contact fatigue life by the amplitude of the ratio of orthogonal shear stress ? yz to Vickers hardness Hv, considering the case that every hardness distribution is the same to each other, the fatigue life of the Ni rich P/F roller was rather longer than that of the steel ones. The P/F process effectively improves the microstructure of the P/M material and makes the surface durability of the P/F material with high content of Ni approach to the level of steel. The P/F process was a good method to improve the mechanical properties of the sintered materials.

Zhang, Qiang; Seki, Masanori; Ohue, Yuji; Yoshida, Akira; Murakami, Masahiro; Sato, Masaaki; Konishi, Masanari

306

Effect of Process Parameters on Abnormal Grain Growth during Friction Stir Processing of a Cast Al Alloy  

SciTech Connect

The effects of process parameters and friction stir processing (FSP) run configurations on the stability of nugget microstructure at elevated temperatures were evaluated. Cast plates of an Al-7Si- 0.6Mg alloy were friction stir processed using a combination of tool rotation rates and tool traverse speeds. All single pass runs showed some extent of abnormal grain growth (AGG), whereas multi-pass runs were more resistant to AGG. Additionally, higher tool rpm was found to be beneficial for controlling AGG. These effects were analyzed by comparing the result of this work with other published results and AGG models.

Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John A.; Grant, Glenn J.

2010-11-25

307

Evaluation of Tensile Deformation Properties of Friction Stir Processed Pure Copper: Effect of Processing Parameters and Pass Number  

NASA Astrophysics Data System (ADS)

In this work, the tensile behavior of pure copper including ultimate tensile stress, yield stress, and elongation in the specimens friction stir processed under different processing parameters and pass adding was investigated in detail. The effect of strain hardening, grain refinement, and heat input on the tensile properties of these specimens was explained as well. It was observed that, regarding the aforementioned factors, the processing parameters and pass number could have considerable effects on the tensile deformation properties of the pure copper such as 300 and 47% enhancements in elongation and ultimate strength, respectively. It was demonstrated that higher passes resulted in the development of ultrafine grains (up to 700-800 nm) in the specimens. The fracture surface morphology was also used to further support the elongation results.

Barmouz, Mohsen; Besharati Givi, Mohammad Kazem; Jafari, Jalal

2013-10-01

308

Effects of process parameters on surface roughness in abrasive waterjet cutting of aluminium  

NASA Astrophysics Data System (ADS)

Abrasive waterjet cutting is a novel machining process capable of processing wide range of hard-to-cut materials. Surface roughness of machined parts is one of the major machining characteristics that play an important role in determining the quality of engineering components. This paper shows the influence of process parameters on surface roughness ( R a) which is an important cutting performance measure in abrasive waterjet cutting of aluminium. Taguchi's design of experiments was carried out in order to collect surface roughness values. Experiments were conducted in varying water pressure, nozzle traverse speed, abrasive mass flow rate and standoff distance for cutting aluminium using abrasive waterjet cutting process. The effects of these parameters on surface roughness have been studied based on the experimental results.

Chithirai Pon Selvan, M.; Mohana Sundara Raju, N.; Sachidananda, H. K.

2012-12-01

309

An experimental analysis of process parameters to manufacture metallic micro-channels by micro-milling  

Microsoft Academic Search

Miniaturisation of products is a current megatrend, and it presents a wider range of opportunities to expand manufacturing\\u000a markets. Micro-device design and manufacturing is a growing area of scientific interest for large number of industrial fields.\\u000a This paper reports the characterisation of micro-milling process to manufacture micro-channels in order to understand the\\u000a behaviour of process parameters when a standard milling

Elisa Vázquez; Ciro A. Rodríguez; Alex Elías-Zúñiga; Joaquim Ciurana

2010-01-01

310

Experimental Methodology for Determining Optimum Process Parameters for Production of Hydrous Metal Oxides by Internal Gelation  

SciTech Connect

The objective of this report is to describe a simple but very useful experimental methodology that was used to determine optimum process parameters for preparing several hydrous metal-oxide gel spheres by the internal gelation process. The method is inexpensive and very effective in collection of key gel-forming data that are needed to prepare the hydrous metal-oxide microspheres of the best quality for a number of elements.

Collins, J.L.

2005-10-28

311

Effect of laser processing parameters on the structure of ductile iron  

Microsoft Academic Search

Laser processing of structure sensitive hypereutectic ductile iron, a cast alloy employed for dynamically loaded automative components, was experimentally investigated over a wide range of process parameters: from power (0.5–2.5 kW) and scan rate (7.5–25 mm s?1) leading to solid state transformation, all the way through to melting followed by rapid quenching. Superfine dendritic (at 105 °C s?1) or feathery

S. P. Gadag; M. N. Srinivasan; B. L. Mordike

1995-01-01

312

Dependence of 20-nm C/H CD windows on critical process parameters  

NASA Astrophysics Data System (ADS)

20 nm contact hole (C/H) patterning is applicable for sub-22 nm technology node applications. Dependence of C/H CD window on critical process parameters is important for process stability and repeatability. Post applied baking (PAB) condition, resist thickness, develop time, and dry etch rate are considered to be the most important process parameters for e-beam chain scission resist ZEP520A C/H patterning. In this paper, PAB temperatures (TPAB) are investigated at temperatures between lower than glass transition temperature (TG) and much higher than TF. Effects of these process parameters on 20 nm +/-10% C/H CD window for various pattern densities and e-beam doses are studied. The critical process parameters are determined by their effects on CD window size, C/H sidewall profile, proximity effect immunity, ?CD/?Dose slope, and etch selectivity. Experimental results are summarized below. Thinnest ZEP520A film has the largest 20nm +/-10% CD window on D-D plot for various L/S ratios and doses. The dosage window of smaller C/H CD is larger. The proximity effect is negligible for 50 nm ZEP520A baked at 200°C/300 sec. No apparent effect is found in CD window on D-D plot for develop time as short as 30 sec. PAB condition is most critical than the other process parameters in determining resist density and polymerization which affect e-beam scattering and chain scission in resist film and therefore affects CD resolution and window. PAB condition of 140°C/60 sec is most desirable in terms of CD window on D-D plot, C/H sidewall profile, dry etch rate and proximity effect.

Chen, Wei-Su; Gu, Pei-Yi; Tsai, Ming-Jinn

2010-03-01

313

Effect of Processing Parameters on the Microstructures and Properties of Automobile Brake Drum  

NASA Astrophysics Data System (ADS)

In this study, the effect of processing parameters such as alloy composition and shake-out time on the microstructure and subsequently the mechanical properties of brake drums to the specification of an automobile company had been studied. The results show that processing parameters such as alloy composition (Silicon and Carbon contents) affect the quantity and morphology of the carbides formed while shakeout time affects the size of the carbide. When all other parameters are kept constant, shakeout time of a casting to obtain desired properties can be predicted using a relationship derived from multiple regression analysis in this study work. The relationship is: Shake-out time = -13.8+0.0799Si+6.954GS+0.0467 Hardness.

Oluwadare, G. O.; Atanda, P. O.

314

Effect of Process Parameter on Barium Titanate Stannate (BTS) Materials Sintered at Low Sintering  

NASA Astrophysics Data System (ADS)

Ba(Ti1-xSnx)O3 solid solutions with (x = 0.15, 0.20, 0.30 and 0.40) are synthesized using conventional solid state reaction method. Formation of solid solutions in the range 0 <= x <=0.40 is confirmed using X-ray diffraction technique. Single phase solid solutions with homogeneous grain distribution are observed at relatively low sintering by controlling process parameters viz. sintering time. Composition at optimized temperature (1150 °C) sintered by varying the sintering time, stabilize in cubic perovskite phase. The % experimental density increase with increasing the time of sintering instead of increasing sintering temperature. The lattice parameter increases by increasing the tin composition in the material. This demonstrates that process parameter optimization can lead to single phase at relatively lower sintering-a major advantage for the materials used as capacitor element in MLCC.

Shukla, Alok; Bajpai, P. K.

2011-11-01

315

The effect of processing parameters on the fatigue properties of D357 investment castings  

NASA Astrophysics Data System (ADS)

Investment casting has emerged as one of the most direct and desirable routes from liquid metal to parts of amazing complexity. Metallurgical developments since the late 1980s have enabled the design and manufacture of components used in static- and dynamic-loaded components. Foundry-process parameters used for such applications have been traditionally optimized with respect to static properties and governing mechanisms and are fairly well understood. The goal of this study is to evaluate how the combinations of process parameters that result either in maximum yield strength or maximum ductility also affect the fatigue life of components. The influence of some casting and heat-treatment parameters affecting microstructure (e.g., dendritic arm spacing, silicon-eutectic structure, and precipitation of age-hardening phases) is assessed on both the static tensile properties and fatigue life.

Kennerknecht, S.; Dumant, X.; Tombari, R.; van Biljon, P.

1997-11-01

316

Effect of Die Dimensions on Extrusion Processing Parameters and Properties of DDGS-Based Aquaculture Feeds  

Microsoft Academic Search

Cereal Chem. 84(4):389-398 The goal of this study was to investigate the effect of die nozzle dimensions, barrel temperature profile, and moisture content on DDGS- based extrudate properties and extruder processing parameters. An in- gredient blend containing 40% distillers dried grains with solubles (DDGS), along with soy flour, corn flour, fish meal, whey, mineral and vitamin mix, with a net

Nehru Chevanan; Kasiviswanathan Muthukumarappan; Kurt A. Rosentrater; James L. Julson

2007-01-01

317

Mathematical modelling, parameter identification and adaptive control of single cell protein processes in tower loop bioreactors  

Microsoft Academic Search

In recent years a new type of bioreactors, the tower loop reactor has successfully been applied for production of single cell protein (SCP). For an improved economical operation of these processes — and other applications of this type of reactors — a detailed mathematical modelling is necessary. The large dimension of the production plants used leads to distributed-parameter models; in

Reiner Luttmann; Axel Munack; Manfred Thoma

318

Use of split-disk tests for the process parameters of filament wound epoxy composite tubes  

Microsoft Academic Search

The aim of this study was to investigate processing parameters of continuous fiber reinforced epoxy composite tubes produced by the filament winding technique. For this purpose, split-disk tests (according to ASTM D-2290 standard) were performed for the specimens produced with two different epoxy resin systems, five different fiber materials and five different winding angles. By determining the hoop tensile strength

Cevdet Kaynak; E. Salim Erdiller; Levend Parnas; Fikret Senel

2005-01-01

319

Process Parameters Optimization for Energy Saving in Paper Machine Dryer Section  

Microsoft Academic Search

Due to high energy consumption in the Chinese paper industry, this study considers higher-energy efficiency for the multicylinder dryer section of paper machines. A common situation in the Chinese paper industry is that energy is consumed in extensive mode. In order to improve the energy efficiency of the paper machine dryer section, deeper analysis and optimization of process parameters are

Yugang Li; Huanbin Liu; Jigeng Li; Jinsong Tao

2011-01-01

320

Identification of CTOA and fracture process parameters by drop weight test and finite element simulation  

Microsoft Academic Search

This paper presents a new technique that is able to predict ductile fracture propagation occurrences in large metallic structures, by means of an appropriate application of the finite element modelling. This technique takes account of a cohesive zone in the vicinity of the crack tip, where a nodal release technique is implemented. Two parameters, governing the process zone of the

P. Salvini; A. Fonzo; G. Mannucci

2003-01-01

321

Agglomeration of gibbsite Al(OH) 3 crystals in Bayer liquors. Influence of the process parameters  

Microsoft Academic Search

Agglomeration of gibbsite (Al(OH)3) crystals is an important stage of the Bayer process. In the present study, using a crystallizer working at constant supersaturation with time, we determine the agglomeration kinetics of gibbsite as a function of different experimental parameters. The effect of the crystallization temperature, supersaturation, seed mass, stirring rate and seed size is investigated. An interpretation of the

I. Seyssiecq; S. Veesler; R. Boistelle; J. M. Lamérant

1998-01-01

322

Impact of selected process parameters on crust flaking of frozen partly baked bread  

Microsoft Academic Search

Partially baked bread or partly baked bread can be frozen to extend its shelf life. Freezing can also be responsible for damage such as crust flaking. This paper presents a study aimed at identifying the process parameters that can interact with crust flaking. The study used a French baguette as a model system. The effect of proving condition (50% and

A. Le Bail; J. Y. Monteau; F. Margerie; T. Lucas; A. Chargelegue; Y. Reverdy

2005-01-01

323

Orthogonal experiment and analysis on process parameters of bowl feed polishing (BFP)  

NASA Astrophysics Data System (ADS)

With the development of science and technology, the demand for high-precision product is increasing continuously. Ultra-smooth surface with sub-nanometer roughness has extensive applications in the field of soft X-ray optics, high power laser and laser gyro. Bowl feed polishing (BFP) technology is an effective ultra-smooth surface processing method, but the polishing process of BFP which is affected by a lot of factors is extremely complex and difficult to control. It is important to understand the effect of the process variables such as abrasive particle size, concentration of abrasive particle, speed of polishing pad, acidity and polishing time in the process of BFP. They are very important parameters that must be carefully formulated to achieve desired material removal rates and surface roughness. Using a design of experiment (DOE) approach, this study was performed investigating the main effect of the each parameter during K9 BFP. A better understanding of the interaction behavior between the various parameters and the effect on removal rate and surface roughness is achieved by using the statistical analysis techniques. In the experimental tests, the optimized parameters combination for BFP which were derived from the statistical analysis could be found for material removal rate and better surface roughness through the above experiment results.

Meng, Kai; Wan, Yongjian; Xu, Qinglan; Yang, Yang

2013-08-01

324

An IRT Model with a Parameter-Driven Process for Change  

ERIC Educational Resources Information Center

An IRT model with a parameter-driven process for change is proposed. Quantitative differences between persons are taken into account by a continuous latent variable, as in common IRT models. In addition, qualitative inter-individual differences and auto-dependencies are accounted for by assuming within-subject variability with respect to the…

Rijmen, Frank; De Boeck, Paul; van der Maas, Han L. J.

2005-01-01

325

Optimal bayesian control of a nonlinear regression process with unknown parameters  

Microsoft Academic Search

We have considered the decision problem facing an agent controlling a nonlinear regression process when parameters in the mean function and in the error distribution are unknown. The agent faces a tradeoff between accumulating information by varying the values of the regressors and accumulating one-period reward by following the one-period expected reward maximizing policy. We show that the problem can

Nlcholas M. Kiefer; Yaw Nyarko

326

Experimental investigation of effects of cutting parameters on surface roughness in the WEDM process  

Microsoft Academic Search

The experimental study presented in this paper aims to select the most suitable cutting and offset parameter combination for the wire electrical discharge machining process in order to get the desired surface roughness value for the machined workpieces. A series of experiments have been performed on 1040 steel material of thicknesses 30, 60 and 80 mm, and on 2379 and

Mustafa ?lhan Gökler; Alp Mithat Ozanözgü

2000-01-01

327

Optimisation of process parameters for bioreduction of azo dyes using Bacillus firmus under batch anaerobic condition  

Microsoft Academic Search

A new dye decolourising bacterial strain was isolated from textile wastewater and identified as Bacillus firmus. The study indicated that the bacterium could efficiently decolourise different azo dyes under static culture conditions. Characterisation of the efficiency of azo dye reduction by this isolate using both spectral and HPLC analysis was found to be a function of process parameters which include

C. J. Ogugbue; T. Sawidis

2011-01-01

328

Determination of a suitable parameter field for the active fluid jet polishing process  

NASA Astrophysics Data System (ADS)

In 2012 a well-known company in the field of high precision optics assigned the University of Applied Sciences Deggendorf to determine a suitable parameter field for the active fluid jet polishing (AFJP) process in order to reach a surface accuracy of at least lambda / 5. The active fluid jet polishing is a relatively new and an affordable sub-aperture polishing process. For a fast and precise identification of the parameter field a considered design of experiment is necessary. The available control variables were the rotational speed of the nozzle, the distance between the test object and the jet, the feed rate, the material of the pin inside the nozzle and the material of the test object itself. In order to reach a significant data density on the one hand and to minimize the number of test runs on the other hand a meander shaped tool path was chosen. At each blank nine paths had been driven whereby at each path another parameter combination was picked. Thus with only one test object nine parameter settings may be evaluated. For the automatized analysis of the tracks a software tool was developed. The software evaluates ten sections which orthogonally intersect the nine tracks on the test-lens. The significant measurement parameters per section are the width and the height of each path as well as the surface roughness within the polished tracks. With the aid of these parameters and further statistical evaluations a suitable parameter field for the goal to find a constant and predictable removal spot was determined. Furthermore up to now over 60 test runs have been successfully finished with nine parameter combinations in each case. As a consequence a test evaluation by hand would be very time-consuming and the software facilitates it dramatically.

Maurer, Roland; Biskup, Heiko; Trum, Christian; Rascher, Rolf; Wünsche, Christine

2013-09-01

329

Open-die forging of structurally porous sandwich panels  

Microsoft Academic Search

Structurally porous metal sandwich panels consisting of dense face sheets and porous cores of controlled relative density\\u000a can be manufactured by trapping inert gas during hot isostatic pressing and modifying its distribution via subsequent thermomechanical forming. A plane-strain solution for analyzing the open-die forging of such a plastically compressible\\u000a sandwich panel is developed. An effective yield potential for the face

D. M. Elzey; H. N. G. Wadley

1999-01-01

330

Direct extrusion process analysis with proposed numerical modeling improvements - product quality, process parameters, and microstructure prediction  

NASA Astrophysics Data System (ADS)

A numerical modeling and simulation analysis was performed on the hot-direct extrusion process with the finite element modeling (FEM) software package, DEFORM(TM) 3-D for three case studies. The research demonstrated that a commercially available, industry-accepted numerical simulation software package can predict the material response and microstructure development with simple simulated state variables (i.e. strain, strain rate, and temperature) and easily measured initial material characteristics (e.g. grain diameter). The predicted state variables provided insight into sources for limited extrudate quality, aided in processing improvements, and were the primary variables used to predict material response. The analysis began with studying the influence of tool misalignment and the degree of billet upset on extrudate dimensional quality, measured in terms of tube eccentricity, for a copper tube case study. Under ideal upset and tool alignment conditions, the simulated eccentricity was minimized. If the mandrel had a misalignment that was within tolerance, the eccentricity initially was minor in comparison to the eccentricity produced toward the end of extrusion. Consequently, through the use of DEFORM(TM) 3-D the extrusion mechanics were understood and sources for tube eccentricity were identified. In the second case study, a flow stress model was developed as a function of the state variables for an as-cast homogenized magnesium alloy. The modeled flow stress curve reasonably agreed with experimental compression flow stress data. The model was then implemented into DEFORM(TM) 3-D to utilize the simulated state variables to examine the extrusion of an automobile structural component. It was concluded that once the initial material characteristics are accounted for in the flow stress model it will more accurately and efficiently predict the flow stress response for the actual material being considered than a generic experimental flow stress-based material library entry in DEFORM(TM) 3-D. The third case study assessed an aluminum alloy's microstructure response to hot-direct extrusion processing conditions. The DEFORM(TM) 3-D simulated state variables were incorporated into a dynamic recrystallization (DRX) model that with reasonable accuracy predicted the surface grain structure evolution when compared to experimental results. By knowing the grain structure response the surface physical properties of the extrudate can be deduced.

de Pari, Luigi, Jr.

331

Forging tool shape optimization using pseudo inverse approach and adaptive incremental approach  

NASA Astrophysics Data System (ADS)

This paper presents a simplified finite element method called "Pseudo Inverse Approach" (PIA) for tool shape design and optimization in multi-step cold forging processes. The approach is based on the knowledge of the final part shape. Some intermediate configurations are introduced and corrected by using a free surface method to consider the deformation paths without contact treatment. A robust direct algorithm of plasticity is implemented by using the equivalent stress notion and tensile curve. Numerical tests have shown that the PIA is very fast compared to the incremental approach. The PIA is used in an optimization procedure to automatically design the shapes of the preform tools. Our objective is to find the optimal preforms which minimize the equivalent plastic strain and punch force. The preform shapes are defined by B-Spline curves. A simulated annealing algorithm is adopted for the optimization procedure. The forging results obtained by the PIA are compared to those obtained by the incremental approach to show the efficiency and accuracy of the PIA.

Halouani, A.; Meng, F. J.; Li, Y. M.; Labergère, C.; Abbès, B.; Lafon, P.; Guo, Y. Q.

2013-05-01

332

Effects of processing parameters on mode and stability of laser welding  

NASA Astrophysics Data System (ADS)

The authors have found a third process--unstable-mode welding (UMW) under a certain condition, besides already known stable deep penetration welding (DPW) and stable heat conduction welding (HCW) during high-power CO2 laser welding. UMW has basic feature that the two welding modes (DPW and HCW) appear intermittently, with the penetration depth and weld width jumping between large and small grades. In this paper, the physical phenomena, especially the signal of plasma during welding and the weld-forming of three kinds of process have been investigated. Effects of welding parameters (focal position, laser power and travel speed) on laser welding mode and weld-forming have been comprehensively studied. Double-U curves of laser welding mode transition have been obtained, which indicate the parameter ranges of the three monitored welding process.

Zhang, Xudong; Chen, Wuzhu; Ren, Jialie; Wang, Yong; Huang, Guoqing; Zhang, Hongjun

1996-04-01

333

Influence of process parameters on cutting force and torque during drilling of glass–fiber polyester reinforced composites  

Microsoft Academic Search

This research outlines the Taguchi optimization methodology, which is applied to optimize cutting parameters in drilling of glass fiber reinforced composite (GFRC) material. Analysis of variance (ANOVA) is used to study the effect of process parameters on machining process. This procedure eliminates the need for repeated experiments, time and conserves the material by the conventional procedure. The drilling parameters and

N. S. Mohan; A. Ramachandra; S. M. Kulkarni

2005-01-01

334

Laser Trimming of CuAlMo Thin-Film Resistors: Effect of Laser Processing Parameters  

NASA Astrophysics Data System (ADS)

This paper reports the effect of varying laser trimming process parameters on the electrical performance of a novel CuAlMo thin-film resistor material. The films were prepared on Al2O3 substrates by direct-current (DC) magnetron sputtering, before being laser trimmed to target resistance value. The effect of varying key laser parameters of power, Q-rate, and bite size on the resistor stability and tolerance accuracy were systematically investigated. By reducing laser power and bite size and balancing this with Q-rate setting, significant improvements in resistor stability and resistor tolerance accuracies of less than ±0.5% were achieved.

Birkett, Martin; Penlington, Roger

2012-08-01

335

Microstructures and Mechanical Properties of Ultrafine Grained Ti-47Al-2Cr (at %) Alloy Produced Using Powder Compact Forging  

NASA Astrophysics Data System (ADS)

Development of innovative techniques to produce gamma TiAl based alloys, with good mechanical properties, while still maintaining ultra fine grain size can be rewarding, but also is a great challenge. In the present study study a Ti-47Al-2Cr (at %) alloy has been synthesized by directly forging green powder compacts of a Ti/Al/Cr composite powder produced by high energy mechanical milling of a mixture of elemental Ti, Al, Cr powders. It has been found that the density of the bulk consolidated alloy sample after forging decreases from 95% of the theoretical density in the central region to 84% in the periphery region. The microstructure of the bulk alloy consisted of several Ti rich regions, which was expected to be mainly due to initial powder condition. The room temperature tensile strength of the samples produced from this process was found to be in the range of 115 - 130 MPa. The roles of canning and green powder compact density in determining the forged sample porosity level and distribution are discussed.

Nadakuduru, Vijay N.; Zhang, Deliang; Cao, Peng; Gabbittas, Brian

336

Identification and optimization of critical process parameters for the production of NOMV vaccine against Neisseria meningitidis.  

PubMed

Outer membrane vesicles (OMV) are used as a vaccine against Neisseria meningitidis serogroup B and are traditionally produced with detergent-extraction to remove toxic lipopolysaccharide. Engineered strains with attenuated lipopolysaccharide allowed the use of native vesicles (NOMV) with improved stability and immunogenicity. In the NOMV production process detergents are omitted and vesicle release is stimulated with EDTA extraction (a chelating agent) to enable a higher yield. Many process parameters may change the EDTA extraction efficiency, but it is unknown what the optimal ranges for these parameters are in terms of quality. The present study systematically optimized EDTA extraction and was representative for production at large-scale. Two critical process parameters were identified, harvest point of the cultivation (harvest) and pH of the extraction buffer (pH), which significantly affected yield (7-fold) and bacterial lysis (35-fold). The other quality attributes remained unchanged. Optimization of harvest and pH revealed that the desired low bacterial lysis coincided with intermediate but sufficient yield. High functional immunogenicity and low toxicity of the optimized vaccine were also confirmed. The EDTA extraction is therefore a robust process step which produces high quality OMV if harvest and pH are controlled accurately. PMID:22464965

van de Waterbeemd, Bas; Streefland, Mathieu; van Keulen, Lonneke; van den Ijssel, Jan; de Haan, Alex; Eppink, Michel H; van der Pol, Leo A

2012-03-30

337

Net-Shape Forging of Aerofoil Blade based on Flash Trimming and Compensation methods  

SciTech Connect

In this research, an automatic blade forging die shape optimisation system was developed by using direct compensation and flash trimming algorithms and integrating with the DEFORM 3D software package. To validate the developed system, a 3D blade forging case problem was simulated and optimised with and without the consideration of trimming simulation. The results were compared with actual measurement data of the forged aerofoil blade with excellent results obtained with the fast trimming simulation procedure used.

Lu, B. [Department of Plasticity Forming Engineering, Shanghai Jiao Tong University, Shanghai, 200030 (China); Ou, H. [Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Armstrong, C. G. [School of Mechanical and Aerospace Engineering, Queen's University Belfast, Belfast, BT9 5AH (United Kingdom)

2011-05-04

338

Net-Shape Forging of Aerofoil Blade based on Flash Trimming and Compensation methods  

NASA Astrophysics Data System (ADS)

In this research, an automatic blade forging die shape optimisation system was developed by using direct compensation and flash trimming algorithms and integrating with the DEFORM 3D software package. To validate the developed system, a 3D blade forging case problem was simulated and optimised with and without the consideration of trimming simulation. The results were compared with actual measurement data of the forged aerofoil blade with excellent results obtained with the fast trimming simulation procedure used.

Lu, B.; Ou, H.; Armstrong, C. G.

2011-05-01

339

17Oexcess in meteoric water: as a new isotopic parameter to decipher water cycle processes  

NASA Astrophysics Data System (ADS)

Classical water stable isotopes (dD and d18O) have been used for more than 50 years with the aim to understand the links between water cycle and climate. They provide information on either temperature or precipitation changes depending on the latitudes. Their combination, in the so-called d-excess, brings some information on climatic conditions occurring during non equilibrium processes along air masses histories (evaporation over the Oceans, reevaporation of droplets in convective systems, continental recycling or ice crystals formation). Recently, the possibility to measure with high precision d17O in water has enabled to introduce a new parameter, 17Oexcess, resulting from the combination of d18O and d17O. According to both observations and modeling works, this new isotopic parameter is able to decipher some of the non equilibrium processes: when measured in ice core, it is expected to be a more direct tracer of relative humidity of the oceanic evaporative regions than d-excess. In order to better understand what controls this new parameter as well as to extract the maximum climatic information from the combination of 17Oexcess and d-excess, we present different original studies combining these two parameters in several key regions. First, data collected in Niger, West Africa, at scales ranging from the convective system to the seasonal cycle confirm the strong influence of relative humidity on 17Oexcess through the rain reevaporation process. Second, seasonal cycles in the Zongo Valley (Tropical Bolivia) suggest that rain recycling along air masses trajectories have different signatures on d-excess and 17Oexcess leading to decipher the different processes. Third, we study how local processes (precipitation, sublimation) in polar region (Greenland) can affect 17Oexcess archived in ice core with respect to d-excess records through (1) isotopic measurements of vapor versus precipitation collected at the NEEM station and (2) seasonal cycles measured from snow pits.

Landais, A.; Guillevic, M.; Steen-Larsen, H.; Vimeux, F.; Bouygues, A.; Falourd, S.; Risi, C. M.; Bony, S.

2009-12-01

340

A preliminary evaluation of an F100 engine parameter estimation process using flight data  

NASA Astrophysics Data System (ADS)

The parameter estimation algorithm developed for the F100 engine is described. The algorithm is a two-step process. The first step consists of a Kalman filter estimation of five deterioration parameters, which model the off-nominal behavior of the engine during flight. The second step is based on a simplified steady-state model of the compact engine model (CEM). In this step, the control vector in the CEM is augmented by the deterioration parameters estimated in the first step. The results of an evaluation made using flight data from the F-15 aircraft are presented, indicating that the algorithm can provide reasonable estimates of engine variables for an advanced propulsion control law development.

Maine, Trindel A.; Gilyard, Glenn B.; Lambert, Heather H.

1990-08-01

341

Optimization of Atmospheric Plasma Spray Process Parameters using a Design of Experiment for Alloy 625 coatings  

NASA Astrophysics Data System (ADS)

Alloy 625 is a Ni-based superalloy which is often a good solution to surface engineering problems involving high temperature corrosion, wear, and thermal degradation. Coatings of alloy 625 can be efficiently deposited by thermal spray methods such as Air Plasma Spraying. As in all thermal spray processes, the final properties of the coatings are determined by the spraying parameters. In the present study, a D-optimal experimental design was used to characterize the effects of the APS process parameters on in-flight particle temperature and velocity, and on the oxide content and porosity in the coatings. These results were used to create an empirical model to predict the optimum deposition conditions. A second set of coatings was then deposited to test the model predictions. The optimum spraying conditions produced a coating with less than 4% oxide and less than 2.5% porosity. The process parameters which exhibited the most important effects directly on the oxide content in the coating were particle size, spray distance, and Ar flow rate. The parameters with the largest effects directly on porosity were spray distance, particle size, and current. The particle size, current, and Ar flow rate have an influence on particle velocity and temperature but spray distance did not have a significant effect on either of those characteristics. Thus, knowledge of the in-flight particle characteristics alone was not sufficient to control the final microstructure. The oxidation index and the melting index incorporate all the parameters that were found to be significant in the statistical analyses and correlate well with the measured oxide content and porosity in the coatings.

Azarmi, F.; Coyle, T. W.; Mostaghimi, J.

2008-03-01

342

Modelling of sensory and instrumental texture parameters in processed cheese by near infrared reflectance spectroscopy.  

PubMed

This study investigated the application of near infrared (NIR) reflectance spectroscopy to the measurement of texture (sensory and instrumental) in experimental processed cheese samples. Spectra (750 to 2498 nm) of cheeses were recorded after 2 and 4 weeks storage at 4 degrees C. Trained assessors evaluated 9 sensory properties, a texture profile analyser (TPA) was used to record 5 instrumental parameters and cheese 'meltability' was measured by computer vision. Predictive models for sensory and instrumental texture parameters were developed using partial least squares regression on raw or pre-treated spectral data. Sensory attributes and instrumental texture measurements were modelled with sufficient accuracy to recommend the use of NIR reflectance spectroscopy for routine quality assessment of processed cheese. PMID:16433962

Blazquez, Carmen; Downey, Gerard; O'Callaghan, Donal; Howard, Vincent; Delahunty, Conor; Sheehan, Elizabeth; Everard, Colm; O'Donnell, Colm P

2006-02-01

343

Effective Parameters in Axial Injection Suspension Plasma Spray Process of Alumina-Zirconia Ceramics  

NASA Astrophysics Data System (ADS)

Suspension plasma spray (SPS) is a novel process for producing nano-structured coatings with metastable phases using significantly smaller particles as compared to conventional thermal spraying. Considering the complexity of the system there is an extensive need to better understand the relationship between plasma spray conditions and resulting coating microstructure and defects. In this study, an alumina/8 wt.% yttria-stabilized zirconia was deposited by axial injection SPS process. The effects of principal deposition parameters on the microstructural features are evaluated using the Taguchi design of experiment. The microstructural features include microcracks, porosities, and deposition rate. To better understand the role of the spray parameters, in-flight particle characteristics, i.e., temperature and velocity were also measured. The role of the porosity in this multicomponent structure is studied as well. The results indicate that thermal diffusivity of the coatings, an important property for potential thermal barrier applications, is barely affected by the changes in porosity content.

Tarasi, F.; Medraj, M.; Dolatabadi, A.; Oberste-Berghaus, J.; Moreau, C.

2008-12-01

344

Applying an interferometric exposure model to analyze the influences of process parameters on the linewidth  

NASA Astrophysics Data System (ADS)

We utilize a modified interferometric exposure model, enhanced with the Beer-Lambert law, to study how some process parameters influence the structural dimensions within the whole exposure area. An experimental apparatus is built to verify the accuracy of this model. The simulation results indicate that when the incident angle is larger than 15°, the effect of the beam deformation cannot be neglected. One cannot readily obtain periodic structures with the same dimensions during static exposure because of the Gaussian distribution of the light intensity. The theoretical results match the experimental ones quite well. The variation of Dill's parameter A has a greater influence on the transmittance and the linewidth when A is decreasing. If a poor contrast fringe is exposed in the photoresist, it will not only cause a greater nonuniformity of the structural dimensions but also a decreased aspect ratio in the structure after the development process.

Chien, Cheng-Wei; Chen, Jyh-Chen; Lee, Ju-Yi

2006-11-01

345

Predicting Simulation Parameters of Biological Systems Using a Gaussian Process Model.  

PubMed

Finding optimal parameters for simulating biological systems is usually a very difficult and expensive task in systems biology. Brute force searching is infeasible in practice because of the huge (often infinite) search space. In this article, we propose predicting the parameters efficiently by learning the relationship between system outputs and parameters using regression. However, the conventional parametric regression models suffer from two issues, thus are not applicable to this problem. First, restricting the regression function as a certain fixed type (e.g. linear, polynomial, etc.) introduces too strong assumptions that reduce the model flexibility. Second, conventional regression models fail to take into account the fact that a fixed parameter value may correspond to multiple different outputs due to the stochastic nature of most biological simulations, and the existence of a potentially large number of other factors that affect the simulation outputs. We propose a novel approach based on a Gaussian process model that addresses the two issues jointly. We apply our approach to a tumor vessel growth model and the feedback Wright-Fisher model. The experimental results show that our method can predict the parameter values of both of the two models with high accuracy. PMID:23482410

Zhu, Xiangxin; Welling, Max; Jin, Fang; Lowengrub, John

2012-12-01

346

Designing a System for a Process Parameter Determined through Modified PSO and Fuzzy Neural Network  

Microsoft Academic Search

In the manufacturing industry, the key to retaining a competitive advantage lies in increased yield and reduced a number of\\u000a reworks. Determining the optimal parameters for the process so that the quality characteristics can meet the target is an\\u000a important strategy. Traditional statistical techniques such as response surface methodology and analysis of variance, whose\\u000a basic assumptions must be met, are

Jui-tsung Wong; Kuei-hsien Chen; Chwen-tzeng Su

2008-01-01

347

Ergodicity and Parameter Estimates for Infinite-Dimensional Fractional Ornstein-Uhlenbeck Process  

SciTech Connect

Existence and ergodicity of a strictly stationary solution for linear stochastic evolution equations driven by cylindrical fractional Brownian motion are proved. Ergodic behavior of non-stationary infinite-dimensional fractional Ornstein-Uhlenbeck processes is also studied. Based on these results, strong consistency of suitably defined families of parameter estimators is shown. The general results are applied to linear parabolic and hyperbolic equations perturbed by a fractional noise.

Maslowski, Bohdan [Czech Academy of Sciences, Institute of Mathematics (Czech Republic)], E-mail: maslow@math.cas.cz; Pospisil, Jan [University of West Bohemia, Faculty of Applied Sciences, Department of Mathematics (Czech Republic)], E-mail: jan.pospisil@kma.zcu.cz

2008-06-15

348

MEASURING FLOW PARAMETERS OF PARTICULATE AND POWDERY SOLIDS IN INDUSTRIAL TRANSPORTATION PROCESSES  

Microsoft Academic Search

This paper provides an overview of existing technologies to measure flow parameters, such as material velocity and material concentration, in industrial transportation processes of particulate and powdery solids with a focus on pneumatic conveying. Restrictions, advantages and drawbacks of state of the art measurement principles are discussed. We show that capacitance-based sensing with suitable electrode topology allows for non-invasive, low-cost

A. Fuchs; H. Zangl

2008-01-01

349

Processing parameters affecting the properties of sol-gel-derived modified lead titanate thin films  

SciTech Connect

Calcium modified lead titanate thin films have been prepared by spin-coating of aquo-diol solutions on platinized silicon substrates. The influence of the chemical processing parameters and of the heating rates on the crystallization of the films is studied. Different ferroelectric properties are measured in films prepared under different conditions. These differences are related to the crystalline phases and structural characteristics developed in the films during their preparation.

Calzada, M.L.; Mendiola, J.; Carmona, F.; Ramos, P.; Sirera, R. [C.S.I.C., Madrid (Spain). Inst. Ciencia de Materials

1996-04-01

350

Influence of EDM process parameters in deep hole drilling of Inconel 718  

Microsoft Academic Search

This paper reports on an experimental investigation of small deep hole drilling of Inconel 718 using the EDM process. The\\u000a parameters such as peak current, pulse on-time, duty factor and electrode speed were chosen to study the machining characteristics.\\u000a An electrolytic copper tube of 3 mm diameter was selected as a tool electrode. The experiments were planned using central\\u000a composite design

P. Kuppan; A. Rajadurai; S. Narayanan

2008-01-01

351

Process Parameters in Resistance Projection Welding for Optical Transmission Device Package  

Microsoft Academic Search

The effects of main process parameters and electrode materials on joint quality (charging voltage and operating force) were\\u000a investigated using detailed metallurgical examination and the helium leak test. The electrode materials used for resistance\\u000a projection welding were brass and Cr-Cu alloy. The TO-Can components (cap and header) were nickel-coated SPCC steel. The results\\u000a indicated that when the operating pressure increased,

Her-Yueh Huang; Kuang-Hung Tseng

2011-01-01

352

Effect of Extrusion Process Parameters on the Quality of Buckwheat Flour Mixes 1  

Microsoft Academic Search

Cereal Chem. 75(3):338-345 A response surface analysis using a second-order central composite design was used to study the effect of extrusion process parameters on the extrudate quality of three blends containing buckwheat flour. The extrudates were prepared as three blends. Blend 1 was a 55:40:5 (w\\/w) mix of light buckwheat flour, wheat flour, and nonfat dry milk (NFDM). Blend 2

P. Rayas-Duarte; K. Majewska; C. Doetkott

1998-01-01

353

Influence of process parameters for coating of nickel–phosphorous on carbon fibers  

Microsoft Academic Search

The nickel–phosphorous (Ni–P) coating on carbon fiber was studied, using sodium hypophosphite as a reducing agent in alkaline medium. The effects of process parameters such as time, stabilizer concentrations, pH of the plating bath and plating bath's temperature on the electroless Ni–P coating efficiency were investigated. Structural study using X-ray diffraction (XRD) indicates that nickel deposition rate increases with increasing

Kamal K. Kar; D. Sathiyamoorthy

2009-01-01

354

Isolation of fungi and optimization of process parameters for decolorization of distillery mill effluent  

Microsoft Academic Search

Five different fungi isolated from distillery mill site in which two isolates (DF3 and DF4) had higher capabilities to remove\\u000a color were identified as Emericella nidulans var. lata and Neurospora intermedia, respectively. Optimization of process parameter for decolorization was initially performed to select growth factors which\\u000a were further substantiated by Taguchi approach in which seven factors, %carbon, %nitrogen, duration, pH,

Garima Kaushik; Indu Shekhar Thakur

2009-01-01

355

Fast and Accurate Statistical Static Timing Analysis with Skewed Process Parameter Variation  

Microsoft Academic Search

This paper presents a fast and accurate statistical static timing analysis method that supports skewed non-Gaussian process parameter variations. First, we propose modeling of non-Gaussian sources of variation using a Skew-Normal random variable which can represent a large class of non-Gaussian distributions such as Log-Normal and Poisson. Second, we present a linear gate delay model in terms of this Skew-Normal

Lin Xie; Azadeh Davoodi

2008-01-01

356

Analysis of Process Parameters Affecting Spray-Dried Oily Core Nanocapsules Using Factorial Design  

PubMed Central

The purpose of this work was to optimize the process parameters required for the production of spray-dried oily core nanocapsules (NCs) with targeted size and drug yield using a two-level four-factor fractional factorial experimental design (FFED). The coded process parameters chosen were inlet temperature (X1), feed flow rate (X2), atomizing air flow (X3), and aspiration rate (X4). The produced NCs were characterized for size, yield, morphology, and powder flowability by dynamic light scattering, electron microscope, Carr’s index, and Hausner ratio measurement, respectively. The mean size of produced NCs ranged from 129.5 to 444.8 nm, with yield varying from 14.1% to 31.1%. The statistical analysis indicated an adequate model fit in predicting the effect of process parameters affecting yield. Predicted condition for maximum yield was: inlet temperature 140°C, atomizing air flow 600 L/h, feed flow rate 0.18 L/h, and aspiration air flow set at 100%, which led to a yield of 30.8%. The morphological analysis showed the existence of oily core and spherical nanostructure. The results from powder flowability analysis indicated average Carr’s index and Hausner ratio of 42.77% and 1.76, respectively. Spray-dried oily core NCs with size lower than 200 nm were successfully produced, and the FFED proved to be an effective approach in predicting the production of spray-dried NCs of targeted yield.

Zhang, Tao

2010-01-01

357

Mechanical properties and their microstructure evaluation in the thixoforming process of semi-solid aluminum alloys  

Microsoft Academic Search

Semi-solid forming technology has some advantages over conventional forming processes such as die casting, squeeze casting, and hot\\/cold forging. Thixoforging technology can produce non-dendritic alloys for the semi-solid forming of complex-shaped parts in metal alloys. In this study, the filling behavior and various defects of products were observed, and microstructures and mechanical properties were investigated along with parameters such as

W. G Cho; C. G Kang

2000-01-01

358

Quantitative analysis of beam delivery parameters and treatment process time for proton beam therapy  

SciTech Connect

Purpose: To evaluate patient census, equipment clinical availability, maximum daily treatment capacity, use factor for major beam delivery parameters, and treatment process time for actual treatments delivered by proton therapy systems. Methods: The authors have been recording all beam delivery parameters, including delivered dose, energy, range, spread-out Bragg peak widths, gantry angles, and couch angles for every treatment field in an electronic medical record system. We analyzed delivery system downtimes that had been recorded for every equipment failure and associated incidents. These data were used to evaluate the use factor of beam delivery parameters, the size of the patient census, and the equipment clinical availability of the facility. The duration of each treatment session from patient walk-in and to patient walk-out of the treatment room was measured for 82 patients with cancers at various sites. Results: The yearly average equipment clinical availability in the last 3 yrs (June 2007-August 2010) was 97%, which exceeded the target of 95%. Approximately 2200 patients had been treated as of August 2010. The major disease sites were genitourinary (49%), thoracic (25%), central nervous system (22%), and gastrointestinal (2%). Beams have been delivered in approximately 8300 treatment fields. The use factor for six beam delivery parameters was also evaluated. Analysis of the treatment process times indicated that approximately 80% of this time was spent for patient and equipment setup. The other 20% was spent waiting for beam delivery and beam on. The total treatment process time can be expressed by a quadratic polynomial of the number of fields per session. The maximum daily treatment capacity of our facility using the current treatment processes was estimated to be 133 {+-} 35 patients. Conclusions: This analysis shows that the facility has operated at a high performance level and has treated a large number of patients with a variety of diseases. The use factor of beam delivery parameters varies by disease site. Further improvements in efficiency may be realized in the equipment- and patient-related processes of treatment.

Suzuki, Kazumichi; Gillin, Michael T.; Sahoo, Narayan; Zhu, X. Ronald; Lee, Andrew K.; Lippy, Denise [Departments of Radiation Physics and Radiation Oncology, University of Texas, MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); The Proton Therapy Center Houston, Ltd., L.L.P., 1840 Old Spanish Trail, Houston, Texas 77054 (United States)

2011-07-15

359

Display device for indicating the value of a parameter in a process plant  

DOEpatents

An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually. The integrated process status board (24) is at the apex of an information hierarchy that extends through four levels and provides access at each panel to the full display hierarchy. The control room panels are preferably of a modular construction, permitting the definition of inputs and outputs, the man machine interface, and the plant specific algorithms, to proceed in parallel with the fabrication of the panels, the installation of the equipment and the generic testing thereof.

Scarola, Kenneth (Windsor, CT); Jamison, David S. (Windsor, CT); Manazir, Richard M. (North Canton, CT); Rescorl, Robert L. (Vernon, CT); Harmon, Daryl L. (Enfield, CT)

1993-01-01

360

A Self-Adaptive Parameter Optimization Algorithm in a Real-Time Parallel Image Processing System  

PubMed Central

Aiming at the stalemate that precision, speed, robustness, and other parameters constrain each other in the parallel processed vision servo system, this paper proposed an adaptive load capacity balance strategy on the servo parameters optimization algorithm (ALBPO) to improve the computing precision and to achieve high detection ratio while not reducing the servo circle. We use load capacity functions (LC) to estimate the load for each processor and then make continuous self-adaptation towards a balanced status based on the fluctuated LC results; meanwhile, we pick up a proper set of target detection and location parameters according to the results of LC. Compared with current load balance algorithm, the algorithm proposed in this paper is proceeded under an unknown informed status about the maximum load and the current load of the processors, which means it has great extensibility. Simulation results showed that the ALBPO algorithm has great merits on load balance performance, realizing the optimization of QoS for each processor, fulfilling the balance requirements of servo circle, precision, and robustness of the parallel processed vision servo system.

Li, Ge; Zhang, Xuehe; Zhao, Jie; Zhang, Hongli; Ye, Jianwei; Zhang, Weizhe

2013-01-01

361

A self-adaptive parameter optimization algorithm in a real-time parallel image processing system.  

PubMed

Aiming at the stalemate that precision, speed, robustness, and other parameters constrain each other in the parallel processed vision servo system, this paper proposed an adaptive load capacity balance strategy on the servo parameters optimization algorithm (ALBPO) to improve the computing precision and to achieve high detection ratio while not reducing the servo circle. We use load capacity functions (LC) to estimate the load for each processor and then make continuous self-adaptation towards a balanced status based on the fluctuated LC results; meanwhile, we pick up a proper set of target detection and location parameters according to the results of LC. Compared with current load balance algorithm, the algorithm proposed in this paper is proceeded under an unknown informed status about the maximum load and the current load of the processors, which means it has great extensibility. Simulation results showed that the ALBPO algorithm has great merits on load balance performance, realizing the optimization of QoS for each processor, fulfilling the balance requirements of servo circle, precision, and robustness of the parallel processed vision servo system. PMID:24174920

Li, Ge; Zhang, Xuehe; Zhao, Jie; Zhang, Hongli; Ye, Jianwei; Zhang, Weizhe

2013-09-23

362

Inverse modeling of parameters in a process-based model Biome-BGC at Duke Pine Forest  

Microsoft Academic Search

One important source of uncertainty in model prediction of climate change on terrestrial ecosystems is the uncertainty in model parameters. To quantify the uncertainty in model parameters, a Bayesian inverse modeling approach was used to estimate model parameter and the associated uncertainty in a process-based ecosystem biogeochemical model (Biome-BGC). Data from eddy covariance measurements at the Duke pine forest site

D. Hui

2007-01-01

363

The effect of process parameters on keyhole welding with a 400 W Nd : YAG pulsed laser  

NASA Astrophysics Data System (ADS)

A low average power pulsed Nd : YAG laser is used for bead-on-plate welding of low carbon steel plate. The criterion for welding in the conduction and keyhole regime together with the effect of laser process parameters on weld quality is studied. It is established that for a weld with full penetration and velocities viable for industrial applications, welding in the conduction mode would not be suitable. The formation of a keyhole is found to be highly dependent on laser pulse parameters. With an average power in the range 220-240 W and a peak power of 1.8 kW, full penetration through keyhole generation of a 0.7 mm thick st14 sheet metal is achieved.

Torkamany, M. J.; Hamedi, M. J.; Malek, F.; Sabbaghzadeh, J.

2006-11-01

364

A GRAPHICS PROCESSING UNIT-ENABLED, HIGH-RESOLUTION COSMOLOGICAL MICROLENSING PARAMETER SURVEY  

SciTech Connect

In the era of synoptic surveys, the number of known gravitationally lensed quasars is set to increase by over an order of magnitude. These new discoveries will enable a move from single-quasar studies to investigations of statistical samples, presenting new opportunities to test theoretical models for the structure of quasar accretion disks and broad emission line regions (BELRs). As one crucial step in preparing for this influx of new lensed systems, a large-scale exploration of microlensing convergence-shear parameter space is warranted, requiring the computation of O(10{sup 5}) high-resolution magnification maps. Based on properties of known lensed quasars, and expectations from accretion disk/BELR modeling, we identify regions of convergence-shear parameter space, map sizes, smooth matter fractions, and pixel resolutions that should be covered. We describe how the computationally time-consuming task of producing {approx}290,000 magnification maps with sufficient resolution (10,000{sup 2} pixel map{sup -1}) to probe scales from the inner edge of the accretion disk to the BELR can be achieved in {approx}400 days on a 100 teraflop s{sup -1} high-performance computing facility, where the processing performance is achieved with graphics processing units. We illustrate a use-case for the parameter survey by investigating the effects of varying the lens macro-model on accretion disk constraints in the lensed quasar Q2237+0305. We find that although all constraints are consistent within their current error bars, models with more densely packed microlenses tend to predict shallower accretion disk radial temperature profiles. With a large parameter survey such as the one described here, such systematics on microlensing measurements could be fully explored.

Bate, N. F.; Fluke, C. J., E-mail: cfluke@swin.edu.au [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122 (Australia)

2012-01-10

365

An elastic–plastic finite element method for the analysis of powder metal forging  

Microsoft Academic Search

Forging of sintered porous powder metal is studied both theoretically and experimentally. An incremental and piecewise linear elastic–plastic finite element method of solution for the analysis of strain hardening porous material under cold forging is presented. The method is based on Hill’s variational principle for incremental deformations. The overall deformation has been split into a number of stages. The variation

P. S Satsangi; P. C Sharma; R Prakash

2003-01-01

366

Investigations into the high-speed forging of sintered copper powder strips  

Microsoft Academic Search

The present paper reports on an investigation into the various technological aspects of the high-speed forging of sintered copper powder strips. Experiments were conducted and measurements were made in the development of barrelling, the strain variations at the free surface and densification during the high-speed forging of sintered copper powder strips at room temperature under dry and lubricated conditions. The

A. K. Jha; S. Kumar

1997-01-01

367

Harness retained heat to save fuel and time in annealing forgings  

Microsoft Academic Search

The retained heat in hot forged auto transmission gears is being tapped as an energy source for isothermal annealing at the Yoshiwara, Japan Plant of Nissan Motor Co. Ltd. Parts are not allowed to cool after forging, but are instead conveyed directly to an annealing furnace. Energy is saved and productivity is improved via elimination of the time normally needed

1986-01-01

368

Isothermal Forging of Titanium Alloys Using Large Precision-Cast Dies.  

National Technical Information Service (NTIS)

The technology of isothermal forging of titanium alloys in large precision-cast dies was established. Twelve forging die castings were produced in the range of 200 to 1400 lb per die half. MAR-M 200 and IN-100 nickel-base superalloys were selected as die ...

K. M. Kulkarni N. M. Parikh T. Watmough

1970-01-01

369

Effect of Alloying Elements on Thermal Wear of Cast Hot-Forging Die Steels  

Microsoft Academic Search

The effect of main alloying elements on thermal wear of cast hot-forging die steels was studied. The wear mechanism was discussed. The results show that alloying elements have significant influences on the thermal wear of cast hot-forging die steels. The wear rates decrease with an increase in chromium content from 3% to 4% and molybdenum content from 2% to 3%,

Shu-qi WANG; Kang-min CHEN; Xiang-hong CUI; Qi-chuan JIANG; Bian HONG

2006-01-01

370

Winter Weather at Valley Forge 1777-1778: A Lesson in Climatic Reconstruction.  

ERIC Educational Resources Information Center

Notes that the story of George Washington's encampment at Valley Forge is seldom told without reference to the bitter cold winter Washington and his troops endured. Shows how to use historical reports of weather information to allow students to judge for themselves whether the winter at Valley Forge then was harsher than winters in the same area…

Ansley, Mary Jane; Pritchard, Sandra F.

1987-01-01

371

Current steel forgings and their properties for steam generator of nuclear power plant  

Microsoft Academic Search

Current steel forgings used for the construction of steam generators (SGs) for a nuclear power plant (NPP) were introduced from the following three (3) features. (1) Integral type steel forgings such as (i) primary head integrated with nozzles, manways and supports, (ii) steam drum head integrated with nozzle and handhole, (iii) conical shell integrated with cylindrical sections and handholes, have

Komei Suzuki; Ikuo Sato; Mikio Kusuhashi; Hisashi Tsukada

2000-01-01

372

Role of processing parameters on morphology, resistance and composition of laser fired contacts  

NASA Astrophysics Data System (ADS)

Laser processing is a single step, attractive alternative to current multi-step formation of ohmic contacts between an aluminum metallization layer and a silicon substrate in solar cell devices. However, small changes in laser parameters such as pulse duration, power density and laser wavelength can result in significant differences in the contact geometry and electrical properties. Here, the effects of power density and pulse duration on the morphology, resistance and surface concentration of laser fired contacts (LFCs) are examined experimentally. The minimum fluence threshold for forming a contact with measureable resistance through the 100nm SiO2 layer is determined to be 8 J/cm2. In addition, when forming the contact, an outer rim region accumulates on the surface that is comprised of aluminum and silicon. As a result, the entire contact is actually governed by the size of an inner crater region plus this outer rim material, which is in contrast to results reported in the literature for nanosecond pulse durations. These results are in good agreement with independent results reported in the literature for LFCs processed on wafers with substantially different base resistivity and using significantly different processing parameters.

Raghavan, A.; Palmer, T. A.; Domask, A.; Mohney, S.; Reutzel, E. W.; DebRoy, T.

2013-09-01

373

Changes in water quality parameters due to in-sewer processes.  

PubMed

Combined sewer systems contain a large number of organic and inorganic pollutants from both domestic and industrial sources. These pollutants are often retained within the combined sewer system for significant lengths of time before entering sewage treatment works, or being spilt to a watercourse via a combined sewer overflow (CSO) during storm conditions. Currently little knowledge exists concerning the effects of in sewer processes on pollutants. Understanding of in-sewer processes is important for the effective and efficient design of treatment works and CSO chambers and for impact assessments on receiving waters. A series of studies covering storm and dry weather flow conditions were undertaken with the aim of investigating the nature of in-sewer processes. These studies consisted of marking a body of water with a fluorescent tracer. The tracer was then monitored at a series of downstream sites, and discrete samples collected from the body of water as it progressed through the sewer. The samples were analysed for water quality parameters and these results investigated in tandem with the detailed hydraulic information gained through the tracer studies. The results highlight the hydraulic differences between storm and dry weather conditions such as increased travel times and mixing under storm conditions. The Advection Dispersion Equation (ADE) and Aggregated Dead Zone (ADZ) model parameters have been quantified for the tracer data. The ADE mixing coefficient is shown to increase by an order of magnitude for storm conditions. The ADZ dispersive fraction parameter is shown to be approximately constant with flow. Chemical reactions and decay within the sewer system were found to be consistent with oxygen limitation. PMID:12793699

Boxall, J; Shepherd, W; Guymer, I; Fox, K

2003-01-01

374

Removing arsenic from coal under ultrasonic and microwave radiation: The influence of processing parameter  

SciTech Connect

Arsenic is one of the trace elements in coal that we are most concerned about because of its toxicity and environmental persistence. Poisoning is endemic in China and is widespread and locally very severe, which is receiving increased attention throughout the world. In this study, an oxidation method was applied for removing arsenic from two Chinese coals (Yima and Datong) under ultrasonic and microwave radiation. There are many processing parameters that impact the effect of removing arsenic from coal: power of ultrasonic, time in ultrasonic, time in microwave radiation, and the concentration of coal, and these were considered with several levels in this article.

Mi, J.; Ren, J.; Zhang, H.J.; Xie, K.C. [Taiyuan University, Taiyuan (China)

2008-07-01

375

Hot compression deformation behavior and processing parameters of a cast Mg–Gd–Y–Zr alloy  

Microsoft Academic Search

Hot deformation behavior and processing parameters of the cast Mg–9Gd–4Y–0.6Zr alloy were investigated in this paper. For the purposes, uniaxial compression tests were conducted at the temperatures ranging from 623K to 773K and strain rates ranging from 0.001s?1 to 1s?1. The tests revealed that the apparent activation energy was 209kJmol?1, and that the stress exponents were 3.2 and 5.1 within

Li Li; Xinming Zhang

2011-01-01

376

Formulation of Dacarbazine-loaded Cubosomes—Part II: Influence of Process Parameters  

Microsoft Academic Search

The purpose of this study is to investigate the combined influence of process parameters (independent variables) such as homogenization\\u000a speed (X\\u000a 1), duration (X\\u000a 2), and temperature (X\\u000a 3) during the preparation of dacarbazine-loaded cubosomes. Box–Behnken design was used to rationalize the influence of these\\u000a three factors on two responses, namely particle size (Y\\u000a 1) and encapsulation efficiency (Y\\u000a 2).

Di Bei; Jacob Marszalek; Bi-Botti C. Youan

2009-01-01

377

Research into Oil-based Colloidal-Graphite Lubricants for Forging of Al-based Alloys  

SciTech Connect

The presented paper describes the topical problem in metal forging production. It deals with the choice of an optimal lubricant for forging of Al-based alloys. Within the scope of the paper, the properties of several oil-based colloidal-graphite lubricants were investigated. The physicochemical and technological properties of these lubricants are presented. It was found that physicochemical properties of lubricant compositions have an influence on friction coefficient value and quality of forgings.The ring compression method was used to estimate the friction coefficient value. Hydraulic press was used for the test. The comparative analysis of the investigated lubricants was carried out. The forging quality was estimated on the basis of production test. The practical recommendations were given to choose an optimal oil-based colloidal-graphite lubricant for isothermal forging of Al-based alloy.

Petrov, A.; Petrov, P.; Petrov, M. [Moscow State Technical University 'MAMI', Department of Autobody making and metal forging, B.Semenovskaya 38, 107023, Moscow (Russian Federation)

2011-05-04

378

Modelling Hydrological Processes in Presence of Uncertain or Unreliable Forcing Data and Land Surface Parameters  

NASA Astrophysics Data System (ADS)

Construction of a model for simulating hydrological processes, to our opinion, should be based on mathematical description of the real physical heat and water exchange processes occurring in a soil - vegetation/snow cover - atmosphere system rather than on available data. This allows one to create more universal model, which can be applied at different temporal and spatial scales and under different natural conditions. More than that, such a model can be applied for poorly-gauged basins and in the presence of uncertain/unreliable forcing data and land surface parameters, provided that reliable runoff measurements are available at least for several years. The latter is necessary for model calibration to reduce the impact of uncertainties in input data on model results. The present work is intended to confirm the above statements using the land surface model SWAP (Soil Water - Atmosphere - Plants). SWAP is a physically-based model describing the processes of heat and water exchange within a soil-vegetation/snow cover-atmosphere system (SVAS). The model can be applied both for point (or grid cell) simulations of vertical fluxes and state variables of SVAS in atmospheric science applications, and for simulating streamflow on different scales — from small catchments to continental scale river basins. The results of model validations have demonstrated that SWAP is able to reproduce (without calibration) heat and water exchange processes (in particular, hydrological processes) adequately, provided that input data of high quality are available. In poorly-gauged basins, alternative sources of information should be used. Here, the global data sets on forcing data and land surface parameters were used for simulating streamflow from two pan-Arctic river basins (the Mezen and the Pechora basins with an area of 78 000 and 324 000 sq.km, respectively), located in the northeast part of the European Russia. The Mezen and the Pechora basins were represented for modeling purposes by, respectively, 13 and 60 one-degree grid cells connected by river networks. Runoff was modeled for each cell and then transformed by a river routing model to simulate streamflow at a river basin outlet. The land surface parameters for each grid cell were taken from the one-degree global data sets of the Second Global Soil Wetness Project (GSWP-2). Seven soil and vegetation parameters were selected for calibration. Meteorological forcing data were taken from the GSWP-2 3-hour global data sets for the period of 1983-1995. To reduce the systematic errors in precipitation and incoming radiation adjustment factors were applied separately for liquid and solid precipitation, as well as for incoming shortwave and longwave radiation. Their values can be obtained by calibration. Thus there were 11 calibrated parameters. Calibration was performed by means of stochastic optimization technique using daily streamflow measured during 1986-1990 at the Malonisogorskaya gauging station for the Mezen River and at the Oksino gauging station for the Pechora River. Model validation using optimal values of the calibrated parameters was performed for the next 5 years. The Nash and Sutcliffe efficiency of daily runoff simulation for the validation period (for both rivers) was within the range 0.75-0.82, the correlation coefficient equaled to 0.88-0.91, the bias did not exceed 6%. Thus it can be concluded, that the physically-based LSM SWAP can be used as a quite functional tool for hydrological modelling in the case of poor, uncertain and unreliable input data.

Gusev, Ye. M.; Nasonova, O. N.; Dzhogan, L. Ya.

2009-04-01

379

Measurements of gas parameters in plasma-assisted supersonic combustion processes using diode laser spectroscopy  

SciTech Connect

We report a procedure for temperature and water vapour concentration measurements in an unsteady-state combustion zone using diode laser absorption spectroscopy. The procedure involves measurements of the absorption spectrum of water molecules around 1.39 {mu}m. It has been used to determine hydrogen combustion parameters in M = 2 gas flows in the test section of a supersonic wind tunnel. The relatively high intensities of the absorption lines used have enabled direct absorption measurements. We describe a differential technique for measurements of transient absorption spectra, the procedure we used for primary data processing and approaches for determining the gas temperature and H{sub 2}O concentration in the probed zone. The measured absorption spectra are fitted with spectra simulated using parameters from spectroscopic databases. The combustion-time-averaged ({approx}50 ms) gas temperature and water vapour partial pressure in the hot wake region are determined to be 1050 K and 21 Torr, respectively. The large signal-to-noise ratio in our measurements allowed us to assess the temporal behaviour of these parameters. The accuracy in our temperature measurements in the probed zone is {approx}40 K. (laser applications and other topics in quantum electronics)

Bolshov, Mikhail A; Kuritsyn, Yu A; Liger, V V; Mironenko, V R [Institute for Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation); Leonov, S B; Yarantsev, D A [Institute of Thermal Physics of Extreme States, Associated Institute of High Temperaturs, Russian Academy of Sciences (Russian Federation)

2009-09-30

380

Effects of signal spectrum varying on signal processing by parameter-induced stochastic resonance  

NASA Astrophysics Data System (ADS)

The effects of signal spectrum varying on signal processing by the method of parameter-induced stochastic resonance (PSR) are investigated. For a binary signal with a smooth power spectral density (PSD), when the PSD curve becomes sharper and narrower, the performance of the nonlinear system via PSR is better. For a multi-frequency signal formed by sine waves with different frequencies, the larger the signal spectral density is, the lower the ability of the PSR system processing signal is. And the signal-to-noise ratio (SNR) gain of the PSR system is increased with the increasing height of the spectral line. Moreover, with the method of PSR, the stochastic signal (the combination of sine waves and noise) improvement is obvious. The results obtained via this method are superior to those with a linear filter.

Li, Jianlong; Xu, Bohou

2006-02-01

381

Response Surface Method for the Rapid Design of Process Parameters in Tube Hydroforming  

NASA Astrophysics Data System (ADS)

This paper deals with the optimization of tube hydroforming parameters in order reduce defects which may occur at the end of forming process such as necking and wrinkling. We propose a specific methodology based on the coupling between an inverse method for the rapid simulation of tube hydroforming process, and a Response Surface Method based on diffuse approximation. The response surfaces are built using Moving Least Squares approximations and constructed within a moving region of interest which moves across a predefined discrete grid of authorized experimental designs. An application of hydroforming of a bulge from aluminium alloy 6061-T6 tubing has been utilized to validate our methodology. The final design is validated with ABAQUS Explicit Dynamic commercial code.

Chebbah, M. S.; Naceur, H.; Hecini, M.; Belouettar, S.

2007-05-01

382

Tailoring Selective Laser Melting Process Parameters for NiTi Implants  

NASA Astrophysics Data System (ADS)

Complex-shaped NiTi constructions become more and more essential for biomedical applications especially for dental or cranio-maxillofacial implants. The additive manufacturing method of selective laser melting allows realizing complex-shaped elements with predefined porosity and three-dimensional micro-architecture directly out of the design data. We demonstrate that the intentional modification of the applied energy during the SLM-process allows tailoring the transformation temperatures of NiTi entities within the entire construction. Differential scanning calorimetry, x-ray diffraction, and metallographic analysis were employed for the thermal and structural characterizations. In particular, the phase transformation temperatures, the related crystallographic phases, and the formed microstructures of SLM constructions were determined for a series of SLM-processing parameters. The SLM-NiTi exhibits pseudoelastic behavior. In this manner, the properties of NiTi implants can be tailored to build smart implants with pre-defined micro-architecture and advanced performance.

Bormann, Therese; Schumacher, Ralf; Müller, Bert; Mertmann, Matthias; de Wild, Michael

2012-12-01

383

Effect of Processing Parameters on the Mechanical Properties of Interstitial Free Steel Subjected to Friction Stir Processing  

NASA Astrophysics Data System (ADS)

In the present work, the effect of friction stir processing parameters on the mechanical properties of an interstitial free steel was studied. Four rotating speeds (800, 1250, 1600, 2000 rpm) and two traverse speeds (31.5 and 63 mm/min) were employed. On both sides of specimens, a nanograin layer with the thickness and nanograins of 150 ?m and 50-100 nm were formed, respectively. For the specimen processed at rotating speed of 1600 rpm and the traverse speed of 31.5 mm/min, the maximum strength was achieved, which was about 80% increase in the strength comparing to that of base material. For constant traverse speed, the increase in the rotation speed from 800 to 1600 rpm led to a decrease in uniform and total elongation of friction stir processed samples. By contrast, when the rotating speed exceeded 1600 rpm, the uniform and total elongation was increased again, while there was a drop in strength. The results of microhardness indicate more than threefold increase in the hardness of the stirred zone comparing to that of base material.

Chabok, A.; Dehghani, K.

2013-05-01

384

Interaction of process parameters in the laser deposition of YBa2Cu3O7 films  

NASA Astrophysics Data System (ADS)

The electrical and morphological properties of YBa2Cu3O7 films grown on SrTiO3(100) substrates in a laser deposition process using a pulsed KrF excimer laser are investigated. For the first time, a quantitative order of importance of the relevant deposition parameters and their interactions that determine the quality of such films can be given. This is achieved by using statistical methods such as analysis of variance and multiple regression analysis for the design and evaluation of the experiments. The films prepared under optimum conditions grow c-axis oriented with low outgrowth densities and reveal transition temperatures Tc?89 K, resistivities ?(100 K)<=60 ?? cm, and resistance ratios R(300 K)/R(100 K)?3. The surface of the targets used for the deposition turned out to be crucial. Fresh targets yield significantly better electrical properties with a much lower spread of the data. Thus, a region in the process parameter space of YBa2Cu3O7 film deposition has been identified where electrical and morphological properties are at optimum, simultaneously. This is prerequisite for the preparation of multilayer devices.

Heinsohn, J.-K.; Reimer, D.; Richter, A.; Subke, K.-O.; Schilling, M.

1998-04-01

385

Milling Process FEM Simulation for Identification of Material Parameters Directly from Experiments  

NASA Astrophysics Data System (ADS)

An identification procedure for the determination of material parameters that are used for the FEM simulation of milling processes is proposed. This procedure is based on the coupling of a numerical identification procedure and FEM simulations of milling operations. The experimental data result directly from measurements performed during milling experiments. A special device has been instrumented and calibrated to perform force and torque measurements, directly during machining experiments in using a piezoelectric dynamometer and a high frequency charge amplifier. The forces and torques are stored and low pass filtered if necessary, and these data provide the main basis for the identification procedure which is based on coupling 3D FEM simulations of milling and optimization/identification algorithms. The identification approach is mainly based on the Surfaces Response Method in the material parameters space, coupled to a sensitivity analysis. A Moving Least Square Approximation method is used to accelerate the identification process. The material behaviour is described from Johnson-Cook law. A fracture model is also added to consider chip formation and separation. The FEM simulations of milling are performed using explicit ALE based FEM code. The inverse identification method is here applied on a 304L stainless steel and the first results are presented.

Maurel, A.; Fontaine, M.; Thibaud, S.; Michel, G.; Gelin, J. C.

2007-05-01

386

Milling Process FEM Simulation for Identification of Material Parameters Directly from Experiments  

SciTech Connect

An identification procedure for the determination of material parameters that are used for the FEM simulation of milling processes is proposed. This procedure is based on the coupling of a numerical identification procedure and FEM simulations of milling operations. The experimental data result directly from measurements performed during milling experiments. A special device has been instrumented and calibrated to perform force and torque measurements, directly during machining experiments in using a piezoelectric dynamometer and a high frequency charge amplifier. The forces and torques are stored and low pass filtered if necessary, and these data provide the main basis for the identification procedure which is based on coupling 3D FEM simulations of milling and optimization/identification algorithms. The identification approach is mainly based on the Surfaces Response Method in the material parameters space, coupled to a sensitivity analysis. A Moving Least Square Approximation method is used to accelerate the identification process. The material behaviour is described from Johnson-Cook law. A fracture model is also added to consider chip formation and separation. The FEM simulations of milling are performed using explicit ALE based FEM code. The inverse identification method is here applied on a 304L stainless steel and the first results are presented.

Maurel, A.; Fontaine, M.; Thibaud, S.; Michel, G.; Gelin, J. C. [FEMTO-ST Institute / Applied Mechanics Laboratory, ENSMM, 26 rue de l'Epitaphe, 25000 Besancon (France)

2007-05-17

387

Reducing PAH emissions from the iron ore sintering process by optimizing its operation parameters.  

PubMed

This study set out to reduce polycyclic aromatic hydrocarbon (PAH) emissions from the iron ore sintering process by optimizing its operation parameters obtained from the Taguchi experimental design. Four operating parameters, including the water content (Wc; range = 6.0-7.0 wt %), suction pressure (Ps; range = 1000-1400 mmH2O), bed height (Hb; range = 500-600 mm), and type of hearth layer (HL; including sinter, hematite, and limonite) were selected and conducted on a pilot-scale sinter pot to simulate various sintering operating conditions of a real-scale sinter plant. We found that the resultant optimal combination (Wc = 6.5 wt %, Hb = 600 mm, Ps = 1400 mmH2O, and HL = limonite) could reduce the emission factor of total BaP equivalent concentration (EF(BaPeq)) up to 57.6% in comparison with the current operating condition of a real-scale sinter plant (Wc = 6.5 wt %, Hb = 550 mm, Ps = 1200 mmH2O, and HL = sinter). Through the ANOVA analysis, we found that Ps and Hb were the top two parameters affecting total EF(BaPeq) (accounting, respectively, for 70.9% and 21.2% of the total contribution of the four selected parameters). By examining both the sinter productivity and sinter strength, the values obtained from the optimal combination were quite comparable to those of the current operating condition. The above results further confirm the applicability of the obtained optimal combination for the real-scale sinter plant. PMID:19603662

Chen, Yu-Cheng; Tsai, Perng-Jy; Mou, Jin-Luh

2009-06-15

388

Pore-scale determination of parameters for macroscale modeling of evaporation processes in porous media  

NASA Astrophysics Data System (ADS)

Evaporation is an important process in many natural and technical systems, such as the unsaturated zone of the subsurface or microchannel evaporators. For the understanding and prediction of the involved processes, numerical simulations of multiphase flow and transport processes are an important tool. In order to achieve an accurate, physically based description of kinetic interphase mass and heat transfer occurring during evaporation, the numerical model has to account for the interfacial areas between phases. A recently developed model for two-phase flow in porous media is able to account for the involved processes by using interfacial areas explicitly as parameters in the model. The crucial issue, however, is the determination of the relationships between specific interfacial areas, capillary pressure, and saturation in this paper, we present a multiphase lattice Boltzmann model, which allows us to determine these relationships. On the basis of the scanned geometry of a natural porous medium, the relationships between specific interfacial areas, capillary pressure, and saturation are determined. To the best of our knowledge, this is the first time that fluid-solid specific interfacial area relationships have been obtained from pore-scale data. Using these functions, we present the results of macroscale simulations of an evaporator device and of drying in a porous medium.

Ahrenholz, B.; Niessner, J.; Helmig, R.; Krafczyk, M.

2011-07-01

389

Kesan Penggunaan Jenis Tepung terhadap Kelikatan dan Parameter Pemprosesan Produk Goreng Bersalut (Effect of Flour Type on the Viscosity and Processing Parameter of a Fried Coated Product)  

Microsoft Academic Search

This study was done to determine the effect of using wheat, rice and sago flour at two different flour : water ratio on the viscosity and processing parameters of battered, fried banana. Batter was prepared by mixing wheat, rice and sago flour with water at two ratios of 1 : 1 and 1 : 2 (flour : water). Banana (Musa

MEUTIA SANDRA; MOHAMAD YUSOF MASKAT; AIDA WAN; AMINAH ABDULLAH

390

Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly- L-lactide (PLLA): Part I. Basic characteristics  

Microsoft Academic Search

Compounds that had neither calcined nor sintered hydroxyapatite (u-HA) particles (particulate size 0.2–20?m, averaging 3.0?m, Ca\\/P=1.69, and containing CO2-3) uniformly distributed in a poly-L-lactide (PLLA, M?v: 400KDa) matrix with a content of 20–50wt% (with 10% increment) were reinforced into composites by a forging process, which was a unique compression molding, and were then machined on a lathe in order to

Y Shikinami; M Okuno

1999-01-01

391

POD of ultrasonic detection of synthetic hard alpha inclusions in titanium aircraft engine forgings  

SciTech Connect

The probability of detection (POD) of inspection techniques is a key input to estimating the lives of structural components such as aircraft engines. This paper describes work conducted as a part of the development of POD curves for the ultrasonic detection of synthetic hard alpha (SHA) inclusions in titanium aircraft engine forgings. The sample upon which the POD curves are to be based contains four types of right circular SHAs that have been embedded in a representative titanium forging, as well as a number of flat bottomed holes (FBHs). The SHAs were of two sizes, number 3 and number 5, with each size including seeds with nominal nitrogen concentrations of both 3 and 17 wt. %. The FBHs included sizes of number 1, number 3, and number 5. This discreteness of the data poses a number of challenges to standard processes for determining POD. For example, at each concentration of nitrogen, there are only two sizes, with 10 inspection opportunities each. Fully empirical, standard methodologies such as a circumflex versus a provide less than an ideal framework for such an analysis. For example, there is no way to describe the beam limiting effect whereby the signal no longer increases the flaw grows larger than the beam, one can only determine POD at the two concentration levels present in the block, and confidence bounds tend to be broad because of the limited data available for each case. In this paper, we will describe strategies involving the use of physics-based models to overcome these difficulties by allowing the data from all reflectors to be analyzed by a single statistical model. Included will be a discussion of the development of the physics-based model, its comparison to the experimental data (obtained at multiple sites with multiple operators) and its implications regarding the statistical analysis, whose details will be given in a separate article by Li et al. in this volume.

Thompson, R. B. [Center for Nondestructive Evaluation and Departments of Materials Science and Aerospace Engineering, Iowa State University, Ames, IA 50011 (United States); Meeker, W. Q. [Center for Nondestructive Evaluation and Department of Statistics, Iowa State University, Ames, IA 50011 (United States); Brasche, L. J. H. [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

2011-06-23

392

Occupational noise exposure in small scale hand tools manufacturing (forging) industry (SSI) in Northern India.  

PubMed

Occupational noise has been recognized as hazardous for the human beings. A high noise level in forging shops is considered to lower the labour productivity and cause illness however occupational noise is being accepted as an integral part of the job. The present study has been carried out in 5 small scale hand tool forging units (SSI) of different sizes in Northern India in Punjab. Noise levels at various sections were measured. OSHA norms for hearing conservation has been incorporated which includes an exchange rate of 5 dB (A), criterion level at 90 dB (A), criterion time of 8 h, threshold level=80 dB (A), upper limit=140 dB (A) and with F/S response rate. Equivalent sound pressure level (L(eq)) has been measured in various sections of these plants. Noise at various sections like hammer section, cutting presses, punching, grinding and barrelling process was found to be >90 dB (A), which is greater than OSHA norms. A cross-sectional study on the basis of questionnaire has been carried out. The results of which revealed that 68% of the workers are not wearing ear protective equipments out of these 50% were not provided with PPE by the company. About 95% of the workers were suffering speech interference though high noise annoyance was reported by only 20%. It has been established that the maximum noise exposure is being taken by the workers as they are working more than 8h a day for six days per week. More than 90% workers are working 12 to 24 h over time per week which lead to very high noise exposure i.e. 50 to 80% per week higher than exposure time/week in USA or European countries(15, 16)). PMID:19672017

Singh, Lakhwinder Pal; Bhardwaj, Arvind; Deepak, K K; Bedi, Raman

2009-08-01

393

Modeling and parameter identification of the simultaneous saccharification-fermentation process for ethanol production.  

PubMed

Despite many environmental advantages of using alcohol as a fuel, there are still serious questions about its economical feasibility when compared with oil-based fuels. The bioethanol industry needs to be more competitive, and therefore, all stages of its production process must be simple, inexpensive, efficient, and "easy" to control. In recent years, there have been significant improvements in process design, such as in the purification technologies for ethanol dehydration (molecular sieves, pressure swing adsorption, pervaporation, etc.) and in genetic modifications of microbial strains. However, a lot of research effort is still required in optimization and control, where the first step is the development of suitable models of the process, which can be used as a simulated plant, as a soft sensor or as part of the control algorithm. Thus, toward developing good, reliable, and simple but highly predictive models that can be used in the future for optimization and process control applications, in this paper an unstructured and a cybernetic model are proposed and compared for the simultaneous saccharification-fermentation process (SSF) for the production of ethanol from starch by a recombinant Saccharomyces cerevisiae strain. The cybernetic model proposed is a new one that considers the degradation of starch not only into glucose but also into dextrins (reducing sugars) and takes into account the intracellular reactions occurring inside the cells, giving a more detailed description of the process. Furthermore, an identification procedure based on the Metropolis Monte Carlo optimization method coupled with a sensitivity analysis is proposed for the identification of the model's parameters, employing experimental data reported in the literature. PMID:17935346

Ochoa, Silvia; Yoo, Ahrim; Repke, Jens-Uwe; Wozny, Günter; Yang, Dae Ryook

2007-10-13

394

Purification of bioproducts by free-flow zone electrophoresis: choice of processing parameters.  

PubMed

Free-flow zone electrophoresis may be used to purify biological samples, due to differences in electrophoretic mobility, in absence of a matrix--most frequently a gel--thus enabling the biological integrity of even fragile molecules to be preserved. However, the process is more complicated than its principle suggests due to different transport phenomena interfering with electrophoretic migration, with the resultant separation depending both on separation effects and dispersive phenomena. The physical origin of the main effects involved was identified. Mathematical expressions were proposed to estimate the influence of the crescent effect and electrohydrodynamics on the process. In this paper, these equations are used to determine the minimum difference in electrophoretic mobility required for a separation to be achieved with respect to the processing parameters. A methodology is proposed which defines the conditions under which the difference in electrophoretic mobilities equals that calculated when considering the influence of dispersive phenomena. Optimized separations of the whey proteins lactoferrin and albumin, known to interact strongly, and the purification of a monoclonal antibody from a mouse ascitic fluid illustrate the approach. PMID:9662173

Roux-de Balmann, H; Cerro, R M; Sanchez, V

1998-06-01

395

Scaleup of a high-shear granulation process using a normalized impeller work parameter.  

PubMed

A method was evaluated to accurately identify the granulation end points of microcrystalline cellulose formulations by monitoring impeller work during high-shear processing. Impeller watt meters were calibrated in situ to a common standard to enable direct comparison of power values between equipment. Integration of the impeller power (watts) versus time (seconds) profile provides an energy parameter (watt seconds) or "work of granulation" for correlation with physical changes in tablet properties and performance. Granulation end points were accurately predicted for 25-, 65-, and 150-liter manufacturing scales on the basis of development work run on 5.0- and 10-liter equipment using work values normalized for the weight of dry powders in the granulator (watt sec/g). The ability to arrive at functionally equivalent granulation end points, in different equipment and at different impeller speeds, was established through comparison of cohesion indexes (slopes of the tablet breaking strength versus compression force profiles) and granulation size distributions determined by sieve analysis. Work measured at the impeller correlated quantitatively with changes in the granulation bulk and tapped densities, average particle size of the finished powders, and cohesion index, independent of granulator make or model. The observed changes in granulation properties, however, did not correlate with individual process variables such as impeller power (watts) or process time. PMID:10934736

Sirois, P J; Craig, G D

2000-01-01

396

A study of double exposure process design with balanced performance parameters for line/space applications  

NASA Astrophysics Data System (ADS)

As the semiconductor fabrication groundrule has reached the 32nm node, in general there are several possible approaches for the photolithography solution such as the double exposure with 1.35 NA immersion, the high refractive index immersion, the extremely ultra violet (EUV) lithography, nanoimprint lithography etc. Among the four, the easiest approach seems to be the double exposure method at an effective numerical aperture (NA) of 1.35. However, there are still challenges in the design and optimization of the process, such as, the use of appropriate illumination condition, the choice of a good photoresist, and the design of an optical proximity correction (OPC) strategy. Besides these considerations, there is a question as whether we really need the double etch process. To study the double exposure mechanism, we have used a 248 nm deep-UV exposure tool and several well chosen photoresist (one is for Space application and the other is for Line application) to study the photo performance parameters in the merge of two photo exposures. At a numerical aperture (NA) around 0.7, the minimum groundrule we can achieve is the one for a 75 nm logic process with minimum pitch around 220 nm. One approach will be that the features with pitches wider than 440 nm are completed in a single exposure, which includes various isolated lines and spaces, line and space ends, two-dimensional structures, etc. This strategy essentially puts the single exposure pattern under the 0.18 um logic like pitches where mild conventional illumination can produce a balanced performance. Under typical illumination conditions, the photolithographic process under 0.18 um like ground rule is well understood and the optical proximity correction is not complicated. The remaining issues are in the dense pitches, where the double exposure kicks in. We have demonstrated that the double exposure with single development can achieve a process window large enough for a 75 nm logic like process and the OPC behavior such as line through pitch is manageable although OPC correction strategy may require substantial improvement to accommodate two individual exposures. In this paper, we will demonstrate the result of our study of the basic photolithographic performance indicators, such as the exposure latitude (EL), the depth of focus (DOF), the CD through pitch, the line edge roughness (LER) and the mask error factor (MEF) for the optimized process. And we will discuss the choice of photoresists for this special application. It seems that a photoresist with a balanced performance for both the line and space is necessary to realize a good double exposure process. In this paper, we will also present our simulation result of effective resist diffusion length to explore the limit of such approach.

Zhu, Jun; Wu, Peng; Wu, Qiang; Ding, Hua; Li, Xin; Sun, Changjiang

2007-03-01

397

Scalable Hyper-parameter Estimation for Gaussian Process Based Time Series Analysis  

SciTech Connect

Gaussian process (GP) is increasingly becoming popular as a kernel machine learning tool for non-parametric data analysis. Recently, GP has been applied to model non-linear dependencies in time series data. GP based analysis can be used to solve problems of time series prediction, forecasting, missing data imputation, change point detection, anomaly detection, etc. But the use of GP to handle massive scientific time series data sets has been limited, owing to its expensive computational complexity. The primary bottleneck is the handling of the covariance matrix whose size is quadratic in the length of the time series. In this paper we propose a scalable method that exploit the special structure of the covariance matrix for hyper-parameter estimation in GP based learning. The proposed method allows estimation of hyper parameters associated with GP in quadratic time, which is an order of magnitude improvement over standard methods with cubic complexity. Moreover, the proposed method does not require explicit computation of the covariance matrix and hence has memory requirement linear to the length of the time series as opposed to the quadratic memory requirement of standard methods. To further improve the computational complexity of the proposed method, we provide a parallel version to concurrently estimate the log likelihood for a set of time series which is the key step in the hyper-parameter estimation. Performance results on a multi-core system show that our proposed method provides significant speedups as high as 1000, even when running in serial mode, while maintaining a small memory footprint. The parallel version exploits the natural parallelization potential of the serial algorithm and is shown to perform significantly better than the serial faster algorithm, with speedups as high as 10.

Chandola, Varun [ORNL; Vatsavai, Raju [ORNL

2010-01-01

398

Effect of Process Parameters on Friction Force and Material Removal in Oxide Chemical Mechanical Polishing  

NASA Astrophysics Data System (ADS)

The relationship between sliding friction and material removal was investigated using a sensor to measure dynamic friction force according to process parameters such as pressure, velocity, conditioning, abrasive concentration, and slurry pH during oxide chemical mechanical polishing (CMP). Friction force and material removal linearly depend on applied load and relative velocity. A high relative velocity also has an effect on the boundary condition between the wafer and the pad, and friction force reduces with increase in relative velocity. Friction force reduces with polishing time during oxide CMP with ex situ conditioning because of the changes in pad roughness parameters such as Ra, Rp, Rpk, and Rsk. Thus, the in situ conditioning method increases removal rate and improves nonuniformity. Friction force can be uniformly distributed on the oxide wafer as abrasive concentration increases owing to the reduction in friction force loaded on one abrasive particle, improving the nonuniformity of removal rate. In oxide CMP using alkali-based slurry, the effective formation and mechanical removal of the Si-OH bond layer on the SiO2 surface also affect the temporal decrease in friction force and result in a higher removal rate, in comparison with the results of a high friction force and a low removal rate in oxide CMP using neutral-based slurry.

Park, Boumyoung; Lee, Hyunseop; Kim, Youngjin; Kim, Hyoungjae; Jeong, Haedo

2008-12-01

399

Quantitation of neurite growth parameters in explant cultures using a new image processing program.  

PubMed

An interactive image processing program was developed to quantify the effects of various biochemical and physical factors on cultured explants of nerve tissue. We used this method to obtain a growth curve of chick embryo dorsal root ganglia (DRG) in media containing various concentrations of nerve growth factor (NGF). In the past, neurite lengths and numbers were measured manually using collages of 35 mm color photographs or made directly under the microscope. Our new program makes it possible to quantify the growth of whole live, unstained DRG's on photograph collages or digital images with respect to center area, neurite area, total explant area, and the number and length of neurites almost exclusive of background artifacts. After comparing the old and new methods, we conclude that our analysis algorithm correlates well with previously accepted protocols for assessing stimulation and inhibition of growth. It rapidly measures several biologically-relevant properties and provides a means to obtain information on six parameters (neurite area, neurite length, neurite number, center area, total area, neurite density) using a single quantitative method. Neurite area in the presence of 10 ng/ml or 20 ng/ml NGF was the most significantly increased parameter as was expected from previous studies since it includes both neurite length and number as well as any crossing fibers. PMID:15183264

Shah, Amit; Fischer, Charles; Knapp, Charles F; Sisken, Betty F

2004-07-30

400

Science Education and Outreach: Forging a Path to the Future  

NASA Astrophysics Data System (ADS)

The International Year of Astronomy and the Year of Science provide singular opportunities to focus public attention on science in general and the universe in particular in 2009. But what happens on January 1, 2010? How can the science and science education communities build on the initiatives and successes of 2009 to create sustainable programs and efforts to continue to advance science education and literacy objectives for the longer term? The presenter will relate how these questions will be addressed at the annual meeting of the Astronomical Society of the Pacific in Millbrae, California, September 12-16, and how the meeting will provide an opportunity for the science, astronomy, and science education and outreach communities to contribute to the discussion and to share their answers and perspectives with the larger community, and to identify ways in which we can forge that future path together.

Manning, James G.

2009-05-01

401

Combustion synthesis and effects of processing parameters on physical properties of {alpha}-alumina  

SciTech Connect

Fine particle porous {alpha}-alumina has been prepared by a wet chemical method of combustion synthesis using an aqueous precursor containing aluminum nitrate (oxidizer) and carbohydrazide, an organic fuel as starting materials. The aluminum nitrate and carbohydrazide were reacted exothermically at 400--600 C. The synthesis of {alpha}-alumina ({alpha}-Al{sub 2}O{sub 3}) was used as a model for understanding the effects of processing parameters on physical properties such as surface area, average pore size, and residual carbon content. The porous powders were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area analysis and elemental analysis. The decomposition of the starting materials was investigated using differential thermal and thermogravimetric analyses (DTA/TGA). It has been shown that the furnace temperature, fuel/oxidizer ratio, and precursor water content can be tailored to produce powders with different physical properties.

Collins, M.V.; Hirschfeld, D.A.; Shea, L.E.

2000-01-04

402

Effect of process parameters on power requirements of vacuum swing adsorption technology for CO 2 capture from flue gas  

Microsoft Academic Search

This study focuses on the effects of process and operating parameters – feed gas temperature, evacuation pressure and feed concentration – on the performance of carbon dioxide vacuum swing adsorption (CO2VSA) processes for CO2 capture from gas, especially as it affects power consumption. To obtain reliable data on the VSA process, experimental work was conducted on a purposely built three

Jun Zhang; Paul A. Webley; Penny Xiao

2008-01-01

403

Influence of process parameters on yield and composition of gluten fractions obtained in a laboratory scale dough batter procedure  

Microsoft Academic Search

The influence of process parameters during the dough formation step on wheat flour gluten agglomeration and composition in a laboratory scale gluten–starch separation process was studied. In the process, in which a dough was transformed into a batter then poured over a set of vibrating sieves (400, 250 and 125 ?m), increasing water contents, mixing times and speeds during dough

S. A Frederix; C. M Courtin; J. A Delcour

2004-01-01

404

Property and microstructure evaluation as a function of processing parameters: Large HY-80 steel casting for a US Navy submarine  

Microsoft Academic Search

Processing techniques can significantly alter the properties of a material and can ultimately determine whether a component will perform its function safely. This effort involves the investigation of the processing parameters of HY-80 steel castings; specifically a large HY-80 submarine casting that failed while in service due to improper processing. Samples taken from the failed casting were evaluated in the

John E. Holthaus; Michelle G. Koul; Angela L. Moran

2006-01-01

405

Processes, observations and parameters in a coupled surface water-groundwater model  

NASA Astrophysics Data System (ADS)

Hydrological models of surface-water flow and infiltration allow for a process-based representation of recharge to ground water models. Recharge is a fundamental and often difficult to quantify component of a groundwater system, in part because recharge and hydraulic conductivity changes tend to similarly affect hydraulic heads, the most common kind of observations in groundwater systems. Here the goal is to analyze the importance of using recharge derived from hydrologic processes for groundwater model development and furthermore the importance of a spatially distributed value of recharge. To achieve the goal we followed this procedure: 1) independently calibrate and test the groundwater and hydrological models (accomplished as described in Foglia et al., 2007GW, 2009WRR, in press WRR); 2) for the hydrological model, we present a new sensitivity analysis and calibration obtained with a set of observations that provides more detail at low flows, which was identified as important by Foglia et al. (2009); 3) couple the two models (here, one-way coupling transfers infiltration from the surface-water model to the groundwater model after multiplying by an estimated factor); 4) identify important parameters and observations using a sensitivity analysis conducted with linear statistics for this computationally demanding model; 5) use regression in an hypothesis testing framework to explore parameter and observation importance further and also explore resulting estimates and model fit. The analysis is carried out using s physically based models of groundwater flow (MOFLOW-2000) and surface hydrology (TOPKAPI) developed for the Maggia Valley in Southern Switzerland. Calibration and sensitivity analysis were performed using UCODE_2005. Sensitivity analysis is used to identify the most important observations for both the individual and coupled models. As expected, the observations belonging to the hydrological model play a more significant role in the coupled calibration. Results suggest the importance of distributed recharge and allow development of new strategies for its further evaluation in the groundwater model development and calibration.

Foglia, Laura; Hill, Mary; Mehl, Steffen; Burlando, Paolo

2013-04-01

406

Critical process parameters of an acetal-based deep-UV photoresist  

NASA Astrophysics Data System (ADS)

The present paper gives a first introduction into the resist scheme and the chemistry of a newly developed acetal-based, positive tone deep UV photoresist, called RS 1594/E. The material consists of a phenolic polymer, a dissolution inhibitor, and a photoactive compound. The dissolution inhibition of the polymer is achieved using a poly-N,O-acetal, which undergoes an efficient acid catalyzed bond cleavage. The radiation induced catalytic reaction starts at ambient temperatures and the latent image stabilizes in a dark reaction. The process is completed by the application of a post exposure bake resulting in the formation of highly soluble dissolution promoting fragments, namely aldehyde and alcohol derivatives. The properties of the main resist components have been studied in detail and their influence on the lithographic performance is discussed. In addition, new critical process parameters have been identified and their impact on the lithographic performance of RS 1594/E was analyzed. The dissolution rate ratio between exposed and unexposed resist areas, the post exposure bake temperature, and the delay time between exposure and post exposure bake were determined as the most significant parameters and are discussed in more detail. Prolonged intervals are found to be mainly responsible for the increased formation of an insoluble surface inhibition layer (`T-topping') and a significant linewidth decrease. Compared to state-of-the-art materials, RS 1594/E shows a noticeable improvement in delay time behavior. Even after 60 minutes delay between exposure and PEB acceptable results may be achieved without any formation of `T- shaped' profiles, and a nearly constant linewidth. The surface inhibition effect is markedly reduced by the use of certain organic additives and an optimized photoacid generator. SEM pictures of 0.24 micrometers , 0.26 micrometers , and 0.28 micrometers line and space patterns demonstrate the excellent resolution capability of RS 1594/E.

Roeschert, Horst; Przybilla, Klaus J.; Spiess, Walter; Wengenroth, Horst; Pawlowski, Georg

1992-06-01

407

The optimal cutting-parameter selection of heavy cutting process in side milling for SUS304 stainless steel  

Microsoft Academic Search

This paper presents an optimal cutting-parameter design of heavy cutting in side milling for SUS304 stainless steel. The orthogonal\\u000a array with grey-fuzzy logics isapplied to optimize the side milling process with multiple performance characteristics. A grey-fuzzy\\u000a reasoning grade obtained from the grey-fuzzylogics analysis is used as a performance index to determine the optimal cutting\\u000a parameters. The selected cutting parameters are

Chang Ching-Kao; H. S. Lu

2007-01-01

408

Anisotropy induced by the rotary forging of rapidly quenched Nd-Fe-B ribbons  

NASA Astrophysics Data System (ADS)

High-density compacts of rapidly quenched Nd-Fe-B ribbon flakes (MQI, supplied by General Motors) have been produced by rotary forging. It was found that under certain conditions an enhanced magnetization was produced in the axial direction of rotary forging. This effect can be correlated with the density of the compacts, although the mechanism by which it occurs has not been established. The increased magnetic properties were coupled with changes in thermal expansion behaviour and differential thermal analysis revealed the presence of some amorphous material in the high-density rotary forged compacts. The best maximum energy product achieved was 230 kJ/m3.

Rowlinson, N.; Ashraf, M. M.; Harris, I. R.

1990-06-01

409

Effects of Parameters on Inhomogeneous Deformation and Damage in Isothermal Local Loading Forming of Ti-Alloy Component  

NASA Astrophysics Data System (ADS)

Isothermal local loading (ILL) forming technology provides a new way to form largescale rib-web (LSRW) components of Ti-alloy, widely used in the aero-space fields as key load-bearing structures. However, the metal undergoes complex plastic inhomogeneous deformation and microstructural evolution, this will lead to macroscopical forming defects and further damage due to multi-process parameters and local loading method, making the process and forming quality hard to control. Using numerical simulation, combined with experiment, influences of various process parameters on forming process, inhomogeneous deformation and damage have been explored for ILL of LSRW components, such as the types of die-forging mode, frictional conditions, and local loading parameters (partitioning of the loading zone, constraint conditions, and loading pass). Then the reasonable forming conditions for LSRW components of Ti-alloy to be studied are proposed. The practical forming experiment of TA15 LSRW component was achieved successfully and the forging with good forming quality, excellent microstructure, and comprehensive mechanical properties was obtained, which indicates the reliability and practical value of results obtained in this article.

Sun, Zhichao; Yang, He; Sun, Nianguang

2012-03-01

410

Optimizing supercritical antisolvent process parameters to minimize the particle size of paracetamol nanoencapsulated in L-polylactide  

PubMed Central

Background: The aim of this study was to optimize the different process parameters including pressure, temperature, and polymer concentration, to produce fine small spherical particles with a narrow particle size distribution using a supercritical antisolvent method for drug encapsulation. The interaction between different process parameters was also investigated. Methods and results: The optimized process parameters resulted in production of nanoencapsulated paracetamol in L-polylactide with a mean diameter of approximately 300 nm at 120 bar, 30°C, and a polymer concentration of 16 ppm. Thermogravimetric analysis illustrated the thermal characteristics of the nanoparticles. The high electrical charge on the surface of the nanoparticles caused the particles to repel each other, with the high negative zeta potential preventing flocculation. Conclusion: Our results illustrate the effect of different process parameters on particle size and morphology, and validate results obtained via RSM statistical software. Furthermore, the in vitro drug-release profile is consistent with a Korsmeyer–Peppas kinetic model.

Kalani, Mahshid; Yunus, Robiah; Abdullah, Norhafizah

2011-01-01

411

Characterization Of An EBL System: The Influence Of Process Parameters On Thickness Resist And Engraving Shapes  

NASA Astrophysics Data System (ADS)

In LIGA process, the low flexibility due to the use of masks might be overcome using the electron beam of a scansion electron microscope (SEM) instead of the synchrotron radiation. In this way, through the vector control of the beam, it is possible to irradiate a specific path on the resist without using any mask. Anyway, it is important to remark that the Electron Beam Lithography (EBL) can not include all the applications of the X-ray LIGA technique but it could be a valid alternative only for some specific uses. In particular, some limits concerning the impression of high thickness resists are expected. An EBL system based on a SEM was recently implemented by the authors and some tests were carried out to characterize the device performances. Aim of this work is to asses the system performances in terms of maximum impressible thickness resist and shape of the engraved entities. Several tests were carried out by varying the resist thickness and the process parameters.

D'Urso, G.; Longo, M.; Ravasio, C.; Maccarini, G.

2011-01-01

412

The effect of process parameters on kinetics and mechanisms of Co2+ removal by bone char.  

PubMed

Bone char powder, composed mainly of poorly crystalline hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2)), carbon and CaCO(3), has potential applicability in the removal of Co(2+) ions from contaminated effluents. In the present study, the influence of process parameters: particle size, agitation speed, initial pH and initial sorbate concentration, onto kinetics and mechanism of Co(2+)sorption was studied and discussed. In order to describe and compare time evolution of the process under different conditions, the experimental data were analyzed using pseudo-first, pseudo-second and Vermeulen's kinetic models. Generally, experimental results were best fitted with the pseudo-second-order model, which accurately predicted the equilibrium sorbed amounts. The pseudo-second-order rate constant was the most influenced by variations in initial metal concentration and pH, in the investigated ranges. The conclusions about sorption mechanism were derived based on Co(2+) amounts sorbed during time, as well as considering solution pH changes, changes of Ca(2+) amounts released into liquid phase and Ca(2+)/Co(2+) molar ratios. It was concluded that rapid sorption stage was governed by surface complexation reactions, whereas the contribution of the ion-exchange mechanism increased with time and became more significant in the second, slower phase. Experimentally determined maximum sorption capacity towards Co(2+), under optimal conditions, was found to be 0.38 mmol/g. The results show that bone char represents cost-effective alternative to synthetic hydroxyapatite sorbent. PMID:22029698

Dimovi?, Slavko D; Smi?iklas, Ivana D; Sljivi?-Ivanovi?, Marija Z; Ple?aš, Ilija B; Slavkovi?-Beškoski, Latinka

2011-01-01

413

A study of processing parameters in thermal-sprayed alumina and zircon mixtures  

NASA Astrophysics Data System (ADS)

A method of plasma spraying of alumina and zircon mixtures to form ZrO2-mullite composites has been proposed and developed. The feedstock is prepared by a combination of mechanical alloying, which allows formation of fine-grained, homogeneous solid-solution mixtures, followed by plasma spheroidization that yields rapid solidified microstructures and enhanced compositional homogeneity. The effects of ball-milling duration and milling media were studied. It was found that zirconia is a more efficient milling media and that increasing milling duration enhanced the dissociation of zircon. Flame spray and plasma spray processes were used to spheroidize the spray-dried powders. The temperature of the flame spray was found to be insufficient to melt the powders completely. The processing parameters of the plasma spray played an important role in zircon decomposition and mullite formation. Increasing the arc current or reducing secondary gas pressure caused more zircon to decompose and more mullite to form after heat treatment at 1200 °C for 3 h. Dissociation of zircon and the amount of mullite for med can be enhanced significantly when using the more efficient, computerized plasma-spraying system and increasing the ball-milling duration from 4 to 8 h.

Li, Y.; Khor, K. A.

2002-06-01

414

Can standard surface EMG processing parameters be used to estimate motor unit global firing rate?  

NASA Astrophysics Data System (ADS)

The relations between motor unit global firing rates and established quantitative measures for processing the surface electromyogram (EMG) signals were explored using a simulation approach. Surface EMG signals were simulated using the reported properties of the first dorsal interosseous muscle in man, and the models were varied systematically, using several hypothetical relations between motor unit electrical and force output, and also using different motor unit firing rate strategies. The utility of using different EMG processing parameters to help estimate global motor unit firing rate was evaluated based on their relations to the number of motor unit action potentials (MUAPs) in the simulated surface EMG signals. Our results indicate that the relation between motor unit electrical and mechanical properties, and the motor unit firing rate scheme are all important factors determining the form of the relation between surface EMG amplitude and motor unit global firing rate. Conversely, these factors have less impact on the relations between turn or zero-crossing point counts and the number of MUAPs in surface EMG. We observed that the number of turn or zero-crossing points tends to saturate with the increase in the MUAP number in surface EMG, limiting the utility of these measures as estimates of MUAP number. The simulation results also indicate that the mean or median frequency of the surface EMG power spectrum is a poor indicator of the global motor unit firing rate.

Zhou, Ping; Zev Rymer, William

2004-06-01

415

Characterization Of An EBL System: The Influence Of Process Parameters On Thickness Resist And Engraving Shapes  

SciTech Connect

In LIGA process, the low flexibility due to the use of masks might be overcome using the electron beam of a scansion electron microscope (SEM) instead of the synchrotron radiation. In this way, through the vector control of the beam, it is possible to irradiate a specific path on the resist without using any mask. Anyway, it is important to remark that the Electron Beam Lithography (EBL) can not include all the applications of the X-ray LIGA technique but it could be a valid alternative only for some specific uses. In particular, some limits concerning the impression of high thickness resists are expected. An EBL system based on a SEM was recently implemented by the authors and some tests were carried out to characterize the device performances. Aim of this work is to asses the system performances in terms of maximum impressible thickness resist and shape of the engraved entities. Several tests were carried out by varying the resist thickness and the process parameters.

D'Urso, G.; Longo, M.; Ravasio, C.; Maccarini, G. [University of Bergamo-Dept. of Design and Technologies-Viale Marconi 5, Dalmine (Italy)

2011-01-17

416

Effects of corn processing on growth characteristics, rumen development, and rumen parameters in neonatal dairy calves.  

PubMed

Neonatal Holstein calves were fed texturized calf starters containing 33% whole (WC), dry-rolled (DRC), roasted-rolled (RC), or steam-flaked (SFC) corn to investigate how corn processing method affects intake, growth, rumen and blood metabolites, and rumen development. In the first experiment, 92 Holstein calves (52 male and 40 female) were started at 2 +/- 1 d of age and studied for 42 d. Starter dry matter (DM) intake was measured and fecal scoring conducted daily. Growth and blood parameter measurements were conducted weekly. A subset of 12 male calves (3/treatment) was euthanized at 4 wk of age and rumen tissue sampled for rumen epithelial development measurements. Experiment 2 consisted of 12 male Holstein calves ruminally cannulated at 7 +/- 1 d of age. Rumen fluid and blood samples were collected during wk 2 to 6. In the first experiment, postweaning and overall starter and total DM intake were significantly higher in calves fed starter with DRC than RC or SFC. Postweaning and overall starter and total DM intake were significantly higher in calves fed starter with WC than SFC. Postweaning average daily gain was significantly greater in calves fed starter with DRC than SFC. Blood volatile fatty acid concentrations were significantly higher in calves fed starter with SFC than in calves fed all other treatments. Papillae length and rumen wall thickness at 4 wk were significantly greater in calves fed starter with SFC than DRC and WC, respectively. In experiment 2, calves fed starter with WC had higher rumen pH and lower rumen volatile fatty acid concentrations than calves fed all other starters. Rumen propionate production was increased in calves receiving starter with SFC; however, rumen butyrate production was higher in calves fed starter with RC. Results indicate that the type of processed corn incorporated into calf starter can influence intake, growth, and rumen parameters in neonatal calves. Calves consuming starter containing RC had similar body weight, feed efficiency, and rumen development but increased structural growth and ruminal butyrate production when compared with the other corn processing treatments. PMID:15377622

Lesmeister, K E; Heinrichs, A J

2004-10-01

417

Optimization of quality characteristics parameters in a pulsed metal inert gas welding process using grey-based Taguchi method  

Microsoft Academic Search

Optimization of a manufacturing process has to take into accounts all of the factors that influence the product quality and\\u000a productivity. Optimization of welding process parameters is considerably complex because welding is a multi-variable process,\\u000a which is influenced by a lot of process uncertainties. In this paper, a grey-based Taguchi method has been adopted to optimize\\u000a the pulsed metal inert

Sukhomay Pal; Santosh K. Malviya; Surjya K. Pal; Arun K. Samantaray

2009-01-01

418

"Vitamin E" fortified parenteral lipid emulsions: Plackett-Burman screening of primary process and composition parameters.  

PubMed

The objective of this study was to screen the effect of eight formulations and process parameters on the physical attributes and stability of "Vitamin E"-rich parenteral lipid emulsions. Screening was performed using a 12-run, 8-factor, 2-level Plackett-Burman design. This design was employed to construct polynomial equations that identified the magnitude and direction of the linear effect of homogenization pressure, number of homogenization cycles, primary and secondary emulsifiers, pre-homogenization temperature, oil loading, and ratio of vitamin E to medium-chain triglycerides (MCT) in the oil phase on particle size, polydispersity index, short-term stability, and outlet temperature of manufactured emulsions. The viscosity of vitamin E was reduced from 3700 (100%) to 64 mPa.s (30%) by MCT addition. As viscosity is critical for efficient emulsification, vitamin/MCT ratio was the most significant contributor for the stability of emulsions. Particle size increased from 236 to 388 nm, and percentage vitamin remaining emulsified after 48 h dropped from 100 to 73% with increase in vitamin/MCT ratio from 30/70 to 70/30. Significant decrease in particle size and PI, and an increase in outlet temperature were also observed with increase in homogenization pressure and number of homogenization cycles. Emulsifiers and oil loading, however, had insignificant effect on the responses. Overall, stable submicron emulsions at vitamin/MCT ratio of 30/70 could be prepared at 25,000 psi and 25 cycles in ambient conditions. The identification of these parameters by a well-constructed design demonstrated the utility of screening studies in the "Quality by Design" approach to pharmaceutical product development. PMID:22554350

Alayoubi, Alaadin; Nazzal, Mahmoud; Sylvester, Paul W; Nazzal, Sami

2012-05-04

419

Processing parameters optimization of multiple quality characteristics of open-end rotor spinning process for Bamboo charcoal and CVC blended fibers  

Microsoft Academic Search

In the field of yarn spinning engineering, the importance of the processing parameters taken depends directly on the quality\\u000a characteristics of the yarn. This study aimed to find the optimal processing parameters for an open-end rotor spinning frame\\u000a at work to identify its multiple quality characteristics for yarn. In this study, Bamboo charcoal and cotton 70 %\\/polyester\\u000a 30 % (CVC)

Chung-Feng Jeffrey Kuo; Hsin-Jung Wei; Chang-Chiun Huang; Te-Li Su

2010-01-01

420

Development of Processing Parameters for Ogranic Binders Using Selective Laser Sintering. 2002 NASA Faculty Fellowship Program.  

National Technical Information Service (NTIS)

This document describes rapid prototyping, its relation to Computer Aided Design (CAD), and the application of these techniques to choosing parameters for Selective Laser Sintering (SLS). The document reviews the parameters selected by its author for his ...

A. A. Mobasher

2002-01-01

421

Forgings and bars for nuclear and other special applications (ASME SA-654 with additional requirements)  

SciTech Connect

This standard covers carbon steel and medium- and high-alloy steel forgings and bars for nuclear and associated applications. Material shall conform to the requirements of ASME SA-654 and to the additional requirements of this standard.

Not Available

1981-05-01

422

VIEW OF SMITH FORGING METAL SPECIMEN USING 3,000POUND DROP HAMMER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF SMITH FORGING METAL SPECIMEN USING 3,000-POUND DROP HAMMER NO. 1, MAN TO RIGHT IS OPERATING HAMMER WHILE OTHER SHAPES SPECIMEN. - Cambria Iron Company, Blacksmith Shop, Lower Works, Johnstown, Cambria County, PA

423

75 FR 70689 - Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum-Greenwood Forge Division; Currently...  

Federal Register 2010, 2011, 2012, 2013

...Administration [TA-W-70,376] Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum- Greenwood Forge Division; Currently Known...2, 2009, applicable to workers of Kaiser Aluminum Fabricated Products, LLC, Kaiser...

2010-11-18

424

The powder sintering and isothermal forging of Ti10V-2Fe3Al  

Microsoft Academic Search

The synthetic technology of powder sintering and isothermal forging was explored to prepare a powder Ti-10V-2Fe-3Al (Ti-1023)\\u000a alloy. Hydride-dehydride powder was provided from unqualified Ti-1023 ingot alloy because of “beta fleck” defect. After cold\\u000a isostatic pressing and sintering, the compact presented uniform chemical composition, but lamella alpha microstructure. Isothermal\\u000a forging technology was used to further densify the sintered compact and

Hongzhen Guo; Zhanglong Zhao; Chunyan Duan; Zekun Yao

2008-01-01

425

Rheological study of hot-forged NdFeB and related permanent magnet properties  

Microsoft Academic Search

For the first time, forging at very high strain rates (??>100 s?1) has been used successfully to produce magnets directly from bulk Nd–Fe–B–Cu alloy. This is achieved by reducing significantly the size of the Nd2Fe14B crystallites, which leads to a coercivity of 796 kA m?1 and by developing a Nd2Fe14B c-axis fibre texture along the forging direction, which leads to

S Rivoirard; P de Rango; D Fruchart; Y Chastel; C. L Martin

2001-01-01

426

Structural features of hot-forged carbide steel (high-speed steel–titanium carbide)  

Microsoft Academic Search

The structure of hot-forged R6M5K5–20% TiC carbide steel is examined. In comparison with sintered carbide steels, it has no\\u000a transition ring zone at the interface between the carbide grain and the base metal. The matrix alloy has a fine structure\\u000a and the texture of grains is perpendicular to the forging force.

G. A. Baglyuk; I. D. Martyukhin; T. M. Pavligo; G. G. Serdyuk; V. M. Tkach

2009-01-01

427

Strengthening a high-strength TiAl alloy by hot-forging  

Microsoft Academic Search

As part of efforts to expand the range of applications for TiAl alloy, strengthening was pursued through hot-forging. Using Ti–42Al–10V (at.%), the hot workability of which was improved by introduction of the ? phase, formability testing and material property evaluation were carried out. Blade formation was found to be possible by means of closed-die forging. A fine lamellar structure characterized

Toshimitsu Tetsui; Kentaro Shindo; Satoru Kobayashi; Masao Takeyama

2003-01-01

428

Fatigue behavior and life predictions of notched specimens made of QT and forged microalloyed steels  

Microsoft Academic Search

Fatigue behavior of notched specimens was investigated using circumferentially notched round bar and double-notched flat plate geometries, each with different stress concentration factors. Specimens were made of a commonly used vanadium-based microalloyed forging steel, in both the as-forged and quenched and tempered (QT) conditions. The effects of different notch severities and constraint conditions (i.e. plane stress versus plane strain) on

A. Fatemi; Z. Zeng; A. Plaseied

2004-01-01

429

Impacts of High-Pressure Diecasting Process Parameters on Greenhouse Gas Emissions  

NASA Astrophysics Data System (ADS)

The impacts of some high-pressure diecasting (HPDC) process parameters on greenhouse gas (GHG) emissions are quantified using life cycle analysis (LCA) for both aluminum and magnesium alloys. The study was conducted according to ISO 14040 standards and was based on an automotive component made on cold-chamber HPDC machines operating in typical mass production environments. The aluminum alloy foundry was located in Australia; the magnesium alloy foundry was located in the United States. In both cases, emissions were found to reduce with an increasing HPDC process yield. However, yield variations had only a modest impact on GHG emissions in the aluminum alloy HPDC, due to the excellent in-plant recycling of the alloy and the relatively low emissions from primary aluminum production compared with primary magnesium production. In contrast, for the magnesium alloy, significant reductions in emissions were recorded as the yield increased. This outcome was attributed to the considerable savings achieved in raw material quantities sourced from high-emitting primary production and the use of lower amounts of SF6, a GHG with a very high global warming potential (GWP). These results were found to hold irrespective of changes to the ratio between the primary and secondary alloys in the raw material mix, although the magnitude of the impact was reduced considerably with reductions in the primary alloy component. In the case of the magnesium alloy HPDC, decreases in quality assurance (QA) rejects and cycle times were also found to contribute toward reduced emissions, although their influences were an order of magnitude lower than that of the yield improvements.

Gunasegaram, D. R.; Tharumarajah, A.

2009-08-01

430

Effect of Process Parameters on the Structure and Properties of Galvanized Sheets  

NASA Astrophysics Data System (ADS)

The effect of galvanizing parameters on the structure (spangle size and coating microstructure) and properties (formability and corrosion resistance) of galvanized sheets was studied in a hot dip process simulator (HDPS) in a conventional Pb bearing (0.08-0.10%) zinc bath by varying zinc bath Al level (0.10-0.28%), bath temperature (718-743 K), dipping time (1.5-3.5 s), wiping gas flow rate (200-450 lpm), nozzle distance (15-17 mm) and wiping delay time (0.1-2.1 s). Al level in the range of 0.18-0.24% in combination with dipping time of 1.5-2.5 s and bath temperature of 718-733 K results in superior formability ( E cv: ~9.3 mm) of the composite (thickness: 0.8 mm). High post-dip cooling rates (~25 K/s) suppress spangle growth (spangle size: ~2 mm). The spangle size of the GI sheet strongly influences the corrosion rate which increases from 5.8 to 9.2 mpy with a decrease in spangle size from 17.5 to 3 mm. By controlling the Al level (0.20%) in zinc bath and bath temperature (733 K), the corrosion rate of mini-spangle GI sheet can be controlled to a level of 5.5 mpy.

Shukla, S. K.; Saha, B. B.; Triathi, B. D.; Avtar, Ram

2010-07-01

431

Influence of ion source configuration and its operation parameters on the target sputtering and implantation process  

SciTech Connect

In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to {alpha}-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N{sub 2}-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling.

Shalnov, K. V.; Kukhta, V. R.; Uemura, K. [Nagata Seiki Co, 8-2, Kamisuwa, Tsubame-shi, Niigata-ken, 959-0181 (Japan); Ito, Y. [Nagaoka University of Technology, Nagaoka, 940-2188 (Japan)

2012-06-15

432

Influence of processing parameters on the thickness of sol-gel silica films  

NASA Astrophysics Data System (ADS)

For applications such as integrated optical devices, it is desirable to fabricated thick optical films, e.g. by the sol-gel process, while avoiding some of the problems associated with multilayer deposits. In the present work, alkoxide-derived SiO2 films were deposited by spin-coating onto single crystal silicon wafers, while varying independently several experimental parameters, namely the water/tetraethoxysilane (TEOS) molar ratio R, the volume percentage of TEOS, the aging period of the solutions and the rotational speed of the substrate. It was concluded that the thickness of the as-deposited porous silica gel films increased with decreasing R, as well as with increasing TEOS volume percentage or aging period of the solution (up to a certain point), whereas it showed a maximum when plotted as a function of the substrate rotational speed. Maximum thicknesses in excess of 370 nm were obtained for porous films, for which densification did not cause cracking, while porous undensified films up to 1.2 micrometers thick were also prepared. The conditions under which maximum film thickness is achieved are discussed.

Matos, M. C.; Carvalho, Alvaro M.; Almeida, Rui M.; Ilharco, Laura M.

1992-12-01

433

The effect of process parameters on the surface finish of plasma polymers  

SciTech Connect

The surface finish of plasma polymers deposited in an inductively coupled discharge were measured as a function of gas flow rates. Surface finish was measured both optically and by AFM. The process parameters of the plasma polymerization were found to effect the surface finish. The gases used were trans-2- butene and hydrogen for hydrocarbon polymers. For bromocarbon polymers we added ethylbromide. The smoothest hydrocarbon polymer coatings had an RMS surface finish better than 1 nm. Bumps 200 nm high spaced approximately 1 {mu}m apart grew on the surface of bromocarbon coatings when they were exposed to air. The composition of the bumps was found to be NH{sub 4}Br by XRD and XPS analysis. We believe that nitrogen (from a small leak or desorption) dissociates in the discharge and reacts with hydrogen to form ammonia. The ammonia then reacts with HBr, a dissociation product of ethylbromide, to form NH{sub 4}Br which is dispersed throughout the deposited layer. Humidity facilitates the transport of the NH{sub 4}Br to the surface where it crystallizes. Bump growth was prevented by either dry storage or overcoating with 3 {mu}m of hydrocarbon plasma polymer. Alternatively, the bumps could be washed from the surface with water.

Letts, S.A.; Cook, R.C.; Welch, P.; McEachern, R.; Fearon, E.

1992-12-09

434

Production of polyols via direct hydrolysis of kraft lignin: effect of process parameters.  

PubMed

Kraft lignin (KL) was successfully depolymerized into polyols of moderately high hydroxyl number and yield with moderately low weight-average molecular weight (Mw) via direct hydrolysis using NaOH as a catalyst, without any organic solvent/capping agent. The effects of process parameters including reaction temperature, reaction time, NaOH/lignin ratio (w/w) and substrate concentration were investigated and the polyols/depolymerized lignins (DLs) obtained were characterized with GPC-UV, FTIR-ATR, (1)H NMR, Elemental & TOC analyzer. The best operating conditions appeared to be at 250°C, 1h, and NaOH/lignin ratio ?0.28 with 20 wt.% substrate concentration, leading to <0.5% solid residues and ?92% yield of DL (aliphatic-hydroxyl number ?352 mg KOH/mg and Mw?3310 g/mole), suitable for replacement of polyols in polyurethane foam synthesis. The overall % carbon recovery under the above best conditions was ?90%. A higher temperature favored reduced Mw of the polyols while a longer reaction time promoted dehydration/condensation reactions. PMID:23644065

Mahmood, Nubla; Yuan, Zhongshun; Schmidt, John; Charles Xu, Chunbao

2013-04-06

435

Process parameter effects on material removal in magnetorheological finishing of borosilicate glass.  

PubMed

We investigate the effects of processing parameters on material removal for borosilicate glass. Data are collected on a magnetorheological finishing (MRF) spot taking machine (STM) with a standard aqueous magnetorheological (MR) fluid. Normal and shear forces are measured simultaneously, in situ, with a dynamic dual load cell. Shear stress is found to be independent of nanodiamond concentration, penetration depth, magnetic field strength, and the relative velocity between the part and the rotating MR fluid ribbon. Shear stress, determined primarily by the material mechanical properties, dominates removal in MRF. The addition of nanodiamond abrasives greatly enhances the material removal efficiency, with the removal rate saturating at a high abrasive concentration. The volumetric removal rate (VRR) increases with penetration depth but is insensitive to magnetic field strength. The VRR is strongly correlated with the relative velocity between the ribbon and the part, as expected by the Preston equation. A modified removal rate model for MRF offers a better estimation of MRF removal capability by including nanodiamond concentration and penetration depth. PMID:20357881

Miao, Chunlin; Lambropoulos, John C; Jacobs, Stephen D

2010-04-01

436

Mdodeling a nitrite-dependent anaerobic methane oxidation process: Parameters identification and model evaluation.  

PubMed

Nitrite-dependent anaerobic methane oxidation (n-damo) is a recently discovered process that is intermediated by n-damo bacteria that oxidize methane with nitrite to generate nitrogen gas. In this work, a kinetic model based on Monod type kinetics and diffusion-reaction model was developed to describe the bioprocess. Some key kinetic parameters needed in the model were obtained from a series of batch activity tests and a sequencing batch reactor (SBR) operation over 100days. The growth rate, decay rate, methane affinity constant, nitrite affinity constant and inhibition constant were 0.0277±0.0022d(-1), 0.00216±0.00010d(-1), 0.092±0.005mmolL(-1), 0.91±0.09mmolL(-1) and 4.1±0.5mmolL(-1) for n-damo bacteria at 30°C, respectively. The results showed that the model could simulate actual performance of the SBR in the first 76days, that methane was not a limiting factor at atmospheric pressure for its high affinity, and that the optimum nitrite concentration was 1.92mmolL(-1). PMID:23994967

He, Zhanfei; Cai, Chen; Geng, Sha; Lou, Liping; Xu, Xiangyang; Zheng, Ping; Hu, Baolan

2013-08-14

437

Influence of process parameters on the weld lines formation in rapid heat cycle molding  

NASA Astrophysics Data System (ADS)

The insufficient entanglement of the molecular chains at the v-notch of a weld line impairs the mechanical strength and the surface quality of a plastic product. The rapid heat cycle molding technology (RHCM) has been recently used to enhance surface appearance of the parts, by thermally cycling the mold surface temperature. The mold temperature is the key of RHCM technology because it significantly affects productivity, energy efficiency and the quality of the final polymer part. In this work the influence of mold temperature on the weld lines depth and roughness were studied. Three different materials were tested. To investigate the influence of process parameters, a special mold insert was designed and manufactured. Weld lines geometry and roughness were quantitatively characterized by means of a profilometer. Experimental results show that is possible to increase the temperature to 10° C lower than the glass transition to obtain a high-gloss parts without weld lines with a significant reduction of cycle time and energy consumption.

Fiorotto, Marco; Lucchetta, Giovanni

2011-05-01

438

Investigation of stress corrosion cracking of the cast and forged steel in water  

NASA Astrophysics Data System (ADS)

The aqueous stress corrosion behavior of cast steel and forged steel of the same heat has been examined. It was shown that the activation energy of crack growth of both cast and forged steels was identical, i.e., Q = 5540 cal/mol, and was comparable with the apparent diffusion activation energy of hydrogen in the steel. The da/dt for cast and forged steel increased under both cathodic and anodic polarization conditions. Correspondingly, the steady-state hydrogen permeation flux increased steeply with the increase of polarizing current under either cathodic or anodic polarization. The influences of the polarization upon the da/dt and the hydrogen permeation flux were similar. The K ISCC of the cast steel was larger than that of the forged steel. This may be due to the observation that the steady-state permeation flux for the forged steel was twice as large as that of the cast steel. For both cast and forged steels the fracture modes were clearly dependent upon K I at the crack tip, and a transition from dimple to quasi-cleavage or intergranular was observed on the fracture surfaces with decreasing K I .

Chu, Wu-Yang; Hsiao, Chi-Mei; Li, Wen-Xue; Zhang, Yan-Guo

1984-11-01

439

Model-based identifiable parameter determination applied to a simultaneous saccharification and fermentation process model for bio-ethanol production.  

PubMed

In this work, a methodology for the Model-Based Identifiable Parameter Determination (MBIPD) is presented. This systematic approach is proposed to be used for structure and parameter identification of nonlinear models of biological reaction networks. Usually this kind of problems are over-parameterized with large correlations between parameters. Hence, the related inverse problems for parameter determination and analysis are mathematically ill-posed and numerically difficult to solve. The proposed MBIPD methodology comprises several tasks: i) model selection, ii) tracking of an adequate initial guess and iii) an iterative parameter estimation step which includes an identifiable parameter subset selection (SsS) algorithm and accuracy analysis of the estimated parameters. The SsS algorithm is based on the analysis of the sensitivity matrix by rank revealing factorization methods. Using this, a reduction of the parameter search space to a reasonable subset, which can be reliably and efficiently estimated from available measurements, is achieved. The Simultaneous Saccharification and Fermentation process for bio-ethanol production from cellulosic material is used as case study for testing the methodology. The successful application of MBIPD to the SSF process demonstrates a relatively large reduction in the identified parameter space. It is shown by a cross-validation that using the identified parameters (even though the reduction of the search space), the model is still able to predict the experimental data properly. Moreover, it is shown that the model is easily and efficiently adapted to new process conditions by solving reduced and well conditioned problems. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 2013. PMID:23650252

López C, Diana C; Barz, Tilman; Peñuela, Mariana; Villegas, Adriana; Ochoa, Silvia; Wozny, Günter

2013-05-01

440

Crack suppression behavior with post-process parameters in BaTiO 3-based Ni-MLCCs  

Microsoft Academic Search

Effects of post-process parameters, such as temperature, holding time, and pressure direction, on crack evolution are investigated in BaTiO3-based multilayer ceramic capacitors (MLCCs), showing X7R characteristic. Vickers indentation is conducted at each plane of the MLCCs before and after the post-process. Crack evolution in the MLCCs is definitely suppressed through the post-process. Difference of crack length between directions at same

Dong-Ho Park; Yeon-Gil Jung; Ungyu Paik

2005-01-01

441

Modelling the correlation between cutting and process parameters in high-speed machining of Inconel 718 alloy using an artificial neural network  

Microsoft Academic Search

An artificial neural network (ANN) model was developed for the analysis and prediction of the relationship between cutting and process parameters during high-speed turning of nickel-based, Inconel 718, alloy. The input parameters of the ANN model are the cutting parameters: speed, feed rate, depth of cut, cutting time, and coolant pressure. The output parameters of the model are seven process

E.O. Ezugwu; D. A. Fadare; J. Bonney; R. B. Da Silva; W. F. Sales

2005-01-01

442

Anisotropic embrittlement in high-hardness ESR 4340 steel forgings  

SciTech Connect

ESR 4340 steel forgings tempered to a hardness of HRC 55 exhibit a severe loss of tensile ductility in the short transverse direction which is strain-rate and humidity dependent. The anisotropy is also reflected in blunt-notch Charpy impact energy, but is absent in the sharp-crack fracture toughness. Brittle behavior is associated with regions of smooth intergranular fracture aligned with microstructural banding Scanning Auger microprobe analysis indicates intergranular segregation of phosphorus and sulfur. The anisotropic embrittlement is attributed to an interaction of nonequilibrium segregation on solidification with local equilibrium segregation at grain boundaries during austenitizing. The regions are prone to brittle fracture under impact conditions and abnormal sensitivity to environmental attack during low strain-rate deformation. A relatively sparse distribution of these defects accounts for the discrepancy between smooth bar and blunt-notch tests vs sharp-crack tests. Isotropic properties are restored by homogenization treatment. For application of these steels at extreme hardness levels, homogenization treatment is essential.

Olson, G.B.; Anctil, A.A.; DeSisto, T.S.; Kula, E.B.

1983-08-01

443

A simulation-based design parameter study in the stamping process of an automotive member  

Microsoft Academic Search

This paper is concerned with the quantitative effect of design parameters on a stamped part of the autobody. The considered parameters in this paper are the blank holding force, the draw-bead force and the blank size, which greatly affect the metal flow during stamping. The indicators of formability selected in this paper are failures such as tearing, wrinkling and the

Jung-Han Song; Hoon Huh; Se-Ho Kim

2007-01-01

444

Gas separation using membranes. 1: Optimization of the separation process using new cost parameters  

Microsoft Academic Search

This is the first in a series of papers presenting new concepts for the development of membranes for gas separation. In this paper two new cost parameters, which are useful for costing and optimization of membrane gas separation systems, are described. The new parameters, cost permeability and effective selectivity, can be used to show the direction to be taken in

Anthony B. Hinchliffe; Kenneth E. Porter

1997-01-01

445

A window-based image processing technique for quantitative and qualitative analysis of road traffic parameters  

Microsoft Academic Search

Traffic information is an important tool in the planning, maintenance, and control of any modern transport system. Of special interest to traffic engineers are parameters of traffic flow such as volume, speed, type of vehicle, queue parameters, traffic movements at junctions, etc. Various algorithms, mainly based on background differencing techniques, have been applied for this purpose. Since background-based algorithms are

M. Fathy; M. Y. Siyal

1998-01-01

446

Using radial basis function neural networks to recognize shifts in correlated manufacturing process parameters  

Microsoft Academic Search

Traditional statistical process control (SPC) techniues of control charting are not applicable in many process industries because data from these facilities are autocorrelated. Therefore the reduction in process variability obtained through the use of SPC techniques has not been realized in process industries. Techniques are needed to serve the same function as SPC control charts, that is to identify process

DEBORAH F. COOK; CHIH-CHOU CHIU

1998-01-01

447

OPTICAL IMAGE PROCESSING: Effect of the parameters of a wide-aperture acousto-optic filter on the image processing quality  

NASA Astrophysics Data System (ADS)

The properties of wide-aperture paratellurite crystal acousto-optic filters used for optical image processing are studied. The influence of parameters of these filters on the quality of optical imaging in laser and nonmonochromatic light is studied. The spatial resolution of filters is measured upon laser and nonmonochromatic illumination of objects. Filtration is performed in a broad wavelength range at different powers of a control electric signal. The optimisation of the filter parameters for improving its spatial resolution is discussed.

Voloshinov, V. B.; Bogomolov, D. V.

2006-05-01

448

Processing of thermal parameters for the assessment of geothermal potential of sedimentary basins  

NASA Astrophysics Data System (ADS)

The growing interest on renewable energy sources is stimulating new efforts aimed at the assessment of geothermal potential in several countries, and new developments are expected in the near future. In this framework, a basic step forward is to focus geothermal investigations on geological environments which so far have been relatively neglected. Some intracontinental sedimentary basins could reveal important low enthalpy resources. The evaluation of the geothermal potential in such geological contexts involves the synergic use of geophysical and hydrogeological methodologies. In sedimentary basins a large amount of thermal and hydraulic data is generally available from petroleum wells. Unfortunately, borehole temperature data are often affected by a number of perturbations which make very difficult determination of the true geothermal gradient. In this paper we addressed the importance of the acquisition of thermal parameters (temperature, geothermal gradient, thermal properties of the rock) and the technical processing which is necessary to obtain reliable geothermal characterizations. In particular, techniques for corrections of bottom-hole temperature (BHT) data were reviewed. The objective was to create a working formula usable for computing the undisturbed formation temperature for specific sedimentary basins. As test areas, we analysed the sedimentary basins of northern Italy. Two classical techniques for processing temperature data from oil wells are customarily used: (i) the method by Horner, that requires two or more measurements of bottom-hole temperatures carried out at the same depth but at different shut-in times te and (ii) the technique by Cooper and Jones, in which several physical parameters of the mud and formation need to be known. We applied both methods to data from a number of petroleum explorative wells located in two areas of the Po Plain (Apenninic buried arc and South Piedmont Basin - Pedealpine homocline). From a set of about 40 wells having two or more temperature measurements at a single depth we selected 18 wells with BHTs recorded at te larger than 3.5 hours; the time span between two measurements varies from 1 to 21 hours. In total 71 couples of BHT-te data are available; the mud circulation time is lower or equal to 4.5 hours. Corrections require the knowledge of thermal parameters. We attempted to remedy the existing deficiency of thermal conductivity data of sedimentary rocks with a series of laboratory measurements on several core samples recovered from wells. Moreover, we developed a model for calculating the thermal conductivity of the rock matrix as a function of mineral composition based on the fabric theory and experimental thermal conductivity data. As the conductivity of clay minerals, which are present in most formations, is poorly defined, we applied an inverse approach, in which mineral conductivities are calculated one by one, on condition that the sample bulk thermal conductivity, the porosity and the amount of each mineral phase are known. Analyses show that formation equilibrium temperatures computed with the Horner method are consistent with those obtained by means of the Cooper and Jones method, which gives on average temperatures lower than 2 C only for shut-in times < 10 hours. The corrected temperatures compared with temperatures measured during drill-stem tests show that the proposed corrections are rather accurate. The two data sets give coherent results and the inferred average geothermal gradient is 21.5 mK/m in the Apenninic buried arc area and 25.2 mK/m in the South Piedmont Basin-Pedealpine homocline area. The problem with the Horner method is that it implicitly assumes no physical property contrast between circulating mud and formation, and that the borehole is infinitesimally thin, i.e. it acts as a line source. This has been criticized by many authors. The accuracy of the predicted temperatures depends on the reliability and accuracy of BHT, shut-in time and mud circulation time, and the error increases with the decrease of the shut-in time. On the ot

Pasquale, V.; Chiozzi, P.; Gola, G.; Verdoya, M.

2009-04-01

449

Optimization of process parameters for developing FeCoSiB amorphous microwires through in-rotating-water quenching technique  

NASA Astrophysics Data System (ADS)

The effects of process parameters for the in-rotating-water quenching technique have been investigated with respect to structural, magnetic and giant magneto-impedance (GMI) properties of FeCoSiB alloy microwires. Continuous and ductile amorphous wires have been found with the optimization of process parameters. The structural, magnetic and GMI behaviors have been evaluated as a function of wire diameter. The crystallinity of the wires increases with wire diameter, affecting soft magnetic and GMI properties. Consequently, it is found that the wire of 110 ?m diameter shows superior soft magnetic and GMI properties.

Sarkar, Partha; Roy, Rajat K.; Panda, Ashis K.; Mitra, Amitava

2013-05-01

450

Identification of Friction Parameters from the Inverse Analysis of a Direct Extrusion Test  

SciTech Connect

This work proposes to use a special upsetting test and an optimal direct extrusion one performed to identify the constitutive equation of the material behavior and the friction coefficients directly from the load-stroke curves. The proposed friction test has the advantage to permit to take into account contact phenomena corresponding to new specimen surfaces created during a real bulk cold forming process. A lot of numerical simulations are made with the commercial software FORGE2 in order to study the influence of some design and process parameters. Different friction laws will be identified starting from the classical Coulomb and Tresca ones. All the parameter identifications are made using the Inverse Analysis principle.

Adinel, Gavrus; Thien, Pham Duc [LGCGM Laboratory, EA 3913, INSA de RENNES, UEB, CS70839, F-35708, Rennes-Cedex 7 (France); Henri, Francillette [SCR/CM, UMR 6226, INSA de RENNES, UEB, CS70839, F-35708, Rennes-Cedex 7 (France)

2011-01-17

451

Identification of Friction Parameters from the Inverse Analysis of a Direct Extrusion Test  

NASA Astrophysics Data System (ADS)

This work proposes to use a special upsetting test and an optimal direct extrusion one performed to identify the constitutive equation of the material behavior and the friction coefficients directly from the load-stroke curves. The proposed friction test has the advantage to permit to take into account contact phenomena corresponding to new specimen surfaces created during a real bulk cold forming process. A lot of numerical simulations are made with the commercial software FORGE2 in order to study the influence of some design and process parameters. Different friction laws will be identified starting from the classical Coulomb and Tresca ones. All the parameter identifications are made using the Inverse Analysis principle.

Gavrus, Adinel; Duc Thien, Pham; Francillette, Henri

2011-01-01

452

Valuation method for effects of hot stamping process parameters on product properties using hot forming simulator  

Microsoft Academic Search

Hot stamping is one of the hot forming processes for manufacturing products of lightweight construction such as lightweight vehicles. Knowledge on the characteristics of the hot stamping process is significant in designing and optimizing the process conditions, dies and tools; however, until now, the characteristics of this process, such as the relationships between a product property and die temperature and

Katsuyoshi Ikeuchi; Jun Yanagimoto

2011-01-01

453

Tradeoffs in Data Acquisition and Processing Parameters for Backscatter and Scatterer Size Estimations  

PubMed Central

By analyzing backscattered echo signal power spectra and thereby obtaining backscatter coefficient vs. frequency data, the size of sub-resolution scatterers contributing to echo signals can be estimated. Here we investigate tradeoffs in data acquisition and processing parameters for reference phantom based backscatter and scatterer size estimations. RF echo data from a tissue-mimicking test phantom were acquired using a clinical scanner equipped with linear array transducers. One array has a nominal frequency bandwidth of 5–13 MHz and the other 4–9 MHz. Comparison of spectral estimation methods showed that the Welch method provided spectra yielding more accurate and precise backscatter coefficient and scatterer size estimations than spectra computed by applying rectangular, Hanning, or Hamming windows and much reduced computational load than if using the multitaper method. For small echo signal data block sizes, moderate improvements in scatterer size estimations were obtained using a multitaper method but this significantly increases the computational burden. It is critical to average power spectra from lateral A-lines for the improvement of scatterer size estimation. Averaging approximately 10 independent A-lines laterally, with an axial window length 10 times the center frequency wavelength optimized tradeoffs between spatial resolution and the variance of scatterer size estimates. Applying the concept of a time-bandwidth product this suggests using analysis blocks that contain at least 30 independent samples of the echo signal. The estimation accuracy and precision depend on the ka range where k is the wave number and a is the effective scatterer size. This introduces an ROI depth dependency to the accuracy and precision because of preferential attenuation of higher frequency sound waves in tissue-like media. With the 5–13 MHz transducer ka ranged from 0.5 – 1.6 for scatterers in the test phantom, which is a favorable range, and the accuracy and precision of scatterer size estimations were both within ~5% using optimal analysis block dimensions. When the 4–9 MHz transducer was used, the ka value ranged from 0.3 to 0.8 – 1.1 for the experimental conditions, and the accuracy and precision were found to be ~10% and 10% – 25%, respectively. Although the experiments were done with two specific models of transducers on the test phantom, the results can be generalized to similar clinical arrays available from a variety of manufacturers and/or for different size of scatterers with similar ka range.

Liu, Wu; Zagzebski, James A.

2010-01-01

454

Process Parameters on the Crystallization and Morphology of Hydroxyapatite Powders Prepared by a Hydrolysis Method  

NASA Astrophysics Data System (ADS)

The effects of process parameters on the crystallization and morphology of hydroxyapatite (Ca10(PO4)6(OH)2, HA) powders synthesized from dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD) using a hydrolysis method have been investigated. X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were used to characterize the synthesized powders. When DCPD underwent hydrolysis in 2.5 NaOH solution (Na(aq)) at 303 K to 348 K (30 °C to 75 °C) for 1 hour, the XRD results revealed that HA was obtained for all the as-dried samples. The SEM morphology of the HA powders for DCPD hydrolysis produced at 348 K (75 °C) shows regular alignment and a short rod shape with a size of 200 nm in length and 50 nm in width. With DCPD hydrolysis in 2.5 M NaOH(aq) holding at 348 K (75 °C) for 1 to 24 hours, XRD results demonstrated that all samples were HA and no other phases could be detected. Moreover, the XRD results also show that all the as-dried powders still maintained the HA structure when DCPD underwent hydrolysis in 0.1 to 5 M NaOH(aq) at 348 K (75 °C) for 1 hour. Otherwise, the full transformation from HA to octa-calcium phosphate (OCP, Ca8H2(PO4)6·5H2O) occurred when hydrolysis happened in 10 M NaOH(aq). FT-IR spectra analysis revealed that some carbonated HA (Ca10(PO4)6(CO3), CHA) had formed. The SEM morphology results show that the 60 to 65 nm width of the uniformly long rods with regular alignment formed in the HA powder aggregates when DCPD underwent hydrolysis in 2.5 M NaOH(aq) at 348 K (75 °C) for 1 hour.

Wang, Moo-Chin; Hon, Min-Hsiung; Chen, Hui-Ting; Yen, Feng-Lin; Hung, I.-Ming; Ko, Horng-Huey; Shih, Wei-Jen

2013-07-01

455

Analysis of process parameters in the laser deposition of YBa2Cu3O7 superconducting films by using SVR  

NASA Astrophysics Data System (ADS)

There are several process parameters in the growth of YBa2Cu3O7 superconducting films by using pulsed laser deposition (PLD). The relationship between the response and process parameters is highly nonlinear and quite complicated. It is very valuable to quantitatively estimate the response under different deposition parameters. In this study, according to an experimental data set on the superconducting transition temperature (Tc) and relative resistance ratio (rR) of 17 samples of YBa2Cu3O7 films deposited under various parameters, the support vector regression (SVR) combined with particle swarm optimization (PSO), was proposed to predict the Tc and rR for YBa2Cu3O7 films. The prediction performance of SVR was compared with that of multiple regression analysis (MRA) models. The results strongly support that the generalization ability of SVR model consistently surpasses that of MRA via leave-one-out cross validation (LOOCV). The mean absolute percentage errors for Tc and rR are 0.37% and 1.51% respectively via LOOCV test of SVR. Sensitivity analysis discovered the most sensitive parameters affecting the Tc and rR. This study suggests that the established SVR model can be used to accurately foresee the Tc and rR. And it can be used to optimizing the deposition parameters in the development of YBa2Cu3O7 films via PLD.

Cai, C. Z.; Xiao, T. T.; Tang, J. L.; Huang, S. J.

2013-10-01

456

Three-dimensional resistivity tomography of Vulcan's forge, Vulcano Island, southern Italy  

NASA Astrophysics Data System (ADS)

9,525 DC resistivity measurements were taken along 9 profiles crossing the volcanic edifice of La Fossa di Vulcano (the forge of God Vulcan in ancient Roman mythology), Vulcano Island (Italy) using a total of 958 electrode locations. This unique data set has been inverted in 3D by minimizing the L2 norm of the data misfit using a Gauss-Newton approach. The true 3D inversion was performed using parallel processing on an unstructured tetrahedral mesh containing 75,549 finite-element nodes and 398,208 elements to accurately model the topography of the volcanic edifice. The 3D tomogram shows a very conductive body (>0.1 S/m) comprised inside the Pietre Cotte crater with conductive volumes that are consistent with the position of temperature and CO2 anomalies at the ground surface. This conductive body is interpreted as the main hydrothermal body. It is overlaid by a resistive and cold cap in the bottom of the crater. The position of the conductive body is consistent with the deformation source responsible for the observed 1990-1996 deflation of the volcano associated with a decrease of hydrothermal activity.

Revil, A.; Johnson, T. C.; Finizola, A.

2010-08-01

457

Statistical analysis and optimization of process parameters in Ti6Al4V laser cladding using Nd:YAG laser  

NASA Astrophysics Data System (ADS)

The process parameters of laser cladding have great effect on the clad geometry and dilution. This investigation focuses on the influence of laser power (400-600 W), scanning speed (500-700 mm/min) and powder feed rate (30-60 rev/min) on the shape factor and the cladding-bead geometry (layer width, layer height and molten depth) with regard to injecting Ti6Al4V (TC4) powder on TC4 substrate. The experimental design technique, central composite design (CCD) and response surface methodology (RSM) are used to build the mathematical model. By means of the developed model tested by the analysis of variance (ANOVA) method, the relationship between process parameters and output responses and the interaction among the process parameter are analyzed and discussed in detail. The analysis results indicate that powder feed rate is the dominant factor on the width and height of cladding coating while laser scanning speed has the strongest effect on molten depth of substrate. Finally, the validation results show that the calculated values are in good agreement with measured responses within the allowable range of cladding parameters being used. This makes it possible to acquire a good parameter combination for dilution control. Based on the results of optimization, it is observed that the low level of laser power and high level of laser scanning speed can produce cladding coatings with good quality when powder feed rate is around the center value.

Sun, Yuwen; Hao, Mingzhong

2012-07-01

458

Scaling-up parameters for site restoration process using surfactant-enhanced soil washing coupled with wastewater treatment by Fenton and Fenton-like processes.  

PubMed

Estimation of scaling-up parameters for a site restoration process using a surfactant-enhanced soil washing (SESW) process followed by the application of advanced oxidation processes (Fenton and photo-Fenton) was performed. For the SESW, different parameters were varied and the soil washing efficiency for pesticide (2,4-D) removal assessed. The resulting wastewater was treated using the Fenton reaction in the absence and presence of ultraviolet (UV) radiation for pesticide removal. Results showed that agitation speed of 1550 rpm was preferable for the best pesticide removal from contaminated soil. It was possible to wash contaminated soils with different soil concentrations; however the power drawn was higher as the soil concentration increased. Complete removal of the pesticide and the remaining surfactant was achieved using different reaction conditions. The best degradation conditions were for the photo-Fenton process using [Fe(II)] = 0.3 mM; [H2O2] = 4.0 mM where complete 2,4-D and sodium dodecylsulfate (SDS) removal was observed after 8 and 10 minutes of reaction, respectively. Further increase in the hydrogen peroxide or iron salt concentration did not show any improvement in the reaction rate. Kinetic parameters, i.e. reaction rate constant and scaling-up parameters, were determined. It was shown that, by coupling both processes (SESW and AOPs), it is possible the restoration of contaminated sites. PMID:23530350

Bandala, Erick R; Cossio, Horacio; Sánchez-Lopez, Adriana D; Córdova, Felipe; Peralta-Herández, Juan M; Torres, Luis G

459

Ultrasound-aided leather dyeing: a preliminary investigation on process parameters influencing ultrasonic technology for large-scale production  

Microsoft Academic Search

The application of ultrasound to leather processing has a significant role for more efficient and advanced manufacturing techniques\\u000a for leather production. The effect of important process parameters for scale-up such as mechanical agitation, float, and concentration\\u000a of dye bath has been experimentally examined. The results indicate that float level and dye bath concentration has significant\\u000a effect on exhaustion of dye.

Venkatasubramanian Sivakumar; Gopalaraman Swaminathan; Paruchuri Gangadhar Rao; Thirumalachari Ramasami

2009-01-01

460

Effect of process parameters on porosity distributions in high-pressure die-cast AM50 Mg-alloy  

Microsoft Academic Search

High-pressure die-casting is the preferred manufacturing process for cast Mg-alloy components used for numerous applications. High-pressure die-cast components usually contain micro-porosity that adversely affects their mechanical properties. In this contribution, the effects of three important process parameters, gate velocity, intensification pressure, and melt temperature on the micro-porosity distributions in high-pressure die-cast AM50 Mg-alloy are quantitatively characterized. The amounts of total

S. G. Lee; A. M. Gokhale; G. R. Patel; M. Evans

2006-01-01

461

Study of the effect of process parameters for n-heptylamine plasma polymerization on final layer properties  

Microsoft Academic Search

Plasma polymerization processes are widely used to chemically functionalize surfaces, which properties can be tuned by different operating variables. In this study, thin amine-containing polymer layers were produced on solid substrates in a custom-made cylindrical plasma polymerization reactor by radio frequency glow discharges of n-heptylamine vapours. Carefully planned experiments were conducted to evaluate the importance of four different process parameters

Yves Martin; David Boutin; Patrick Vermette

2007-01-01