bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors dominating joint characteristics in Ti – Al friction welds
Authors: Kim Y.-C. , Fuji A.
Published: February 2003

The dominant factors determining the joint characteristics (strength, ductility etc.) in friction welds between Ti and Al were investigated from both mechanical and metallurgical points of view. The principal factors determining the joint characteristics were not mechanical, as the residual stress and plastic strain generated by the friction welding were not especially high. Instead, it was found that the joint characteristics were dominated mainly by a metallurgical factor, that is, the thickness of the intermetallic compound layer produced at the interface. The critical thickness of the intermetallic compound layer was about 5 νm. When this type of joint is used in a high temperature environment, the working temperature and time should be carefully monitored. For long working times, the joint characteristics were greatly deteriorated as the thickness of the intermetallic compound layer increased.
In situ observations of ferrite – austenite transformations in duplex stainless steel weldments using synchrotron radiation
Authors: Palmer T. A. , Elmer J. W. , Wong Joe
Published: February 2003

Ferrite (δ)-austenite (γ) transformations in the heat affected zone (HAZ) of a gas tungsten arc weld in 2205 duplex stainless steel are observed in real time using spatially resolved X-ray diffraction (SRXRD) with high intensity synchrotron radiation. A map showing the locations of the δ and γ phases with respect to the calculated weld pool dimensions has been constructed from a series of SRXRD scans. Regions of liquid, completely transformed γ, a combination of partially transformed γ with untransformed δ, and untransformed γ + δ are identified. Analysis of each SRXRD pattern provides a semiquantitative definition of both the δ/γ phase balance and the extent of annealing, which are mapped for the first time with respect to the calculated weld pool size and shape. A combination of these analyses provides a unique real time description of the progression of phase transformations in the HAZ. Results show that during heating, δ and γ both show signs of annealing as temperatures approach 550 ° C. The δ phase then starts to transform to γ as temperatures approach 700 ° C. Although supported by thermodynamic calculations, this δ → γ transformation during heating has not been directly observed until now. Following this reaction, the HAZ microstructure evolves in three different ways. For peak temperatures less than approximately 1100 ° C, δ retransforms, reverting to its original base metal fraction on cooling. When peak temperatures exceed approximately 1375 ° C, the microstructure completely transforms to δ before retransforming to a mixture of δ and γ during weld cooling. For peak temperatures between 1100 and 1375 ° C, γ is only partially transformed during both heating and cooling. Using these real time observations, important kinetic information about the transformations occurring in duplex stainless steels during both non-isothermal heating and cooling of welding can be determined.
Solution of inverse heat conduction problem for determining heat input, weld shape, and grain structure during laser welding
Authors: Karkhin V. A. , Plochikhine V. V. , Bergmann H. W.
Published: February 2003

The technique of solving the inverse heat conduction problem to determine the steady state welding conditions corresponding to observable or desired weld features is outlined. The objective function includes calculated and experimental values of the temperature related functions, constraints, and regularisation of unknown parameters. The algorithm used to determine the minimum of the objective function is presented. As an example, the temperature field and its corresponding grain structure have been calculated taking into consideration the latent heat and fluid flow in the laser welding of two aluminium alloys. The weld width and texture orientation have been used as the temperature related functions. The results of the simulations are directly compared with the experimental evidence.
Mechanical and metallurgical properties of welding zone in rail welded via thermite process
Authors: Merıç C. , Atık E. , Şahın S.
Published: February 2003

The quality of railway construction is an important factor in providing safe and comfortable rail transportation. Thermite welding, which is a long established technique, prevents rail failure and derailing of trains. This technique assists in providing a smooth ride and long service life for rails and railway carriages. In the present study, type S49 SAE/AISI 1050 steel rails have been welded via a short preheating thermite process.The hardness distributions of the upper surface and inside sections of the welding zone have been obtained and its microstructure has been examined. In addition, specimens taken from the upper side (head), web, and base of the welding zone were subjected to tensile and Charpy V notch impact tests. In the hardness profiles for these specimens maximum hardness values were observed at the edges of the weld metal. The hardness values were 109 HB at the interface between the melting zone and the heat affected zone, 108 HB in the melting zone, and 104 HB in the unwelded rail region. Examination of the microstructure revealed proeutectoid ferrite and pearlite, but not martensite.
Fracture behaviour of diffusion bonded titanium alloys with strength mismatch
Authors: Koçak M. , Pakdil M. , Çam G.
Published: February 2003

The present study considers the effect of strength mismatch on the fracture behaviour of diffusion bonded joints between commercially pure (CP) Ti and Ti-6Al-4V (Ti64), including dissimilar joints and sandwich structures with strength undermatching and overmatching. The aim of the investigation is to determine the influence of the interlayer thickness (for both higher and lower strength interlayers) and the bond quality on the deformation behaviour and fracture toughness of the joints. The influence of mechanical heterogeneity (strength mismatch) on the fracture behaviour of the interface in dissimilar joints was also investigated. Round bars of CP Ti and Ti64 having a diameter of 40 mm were diffusion bonded as dissimilar butt joints and sandwich structures containing lower strength (undermatching) and higher strength (overmatching) interlayers of different thicknesses. Round transverse tensile specimens and standard four point bend (single edge notch bend) specimens were extracted from the joints via spark erosion cutting. The four point bend specimens were fatigue precracked to introduce a sharp crack after introducing machine notches at the centre of the interlayers in the sandwich structures and at the interface in the dissimilar joints, and tested at room temperature. Some specimens were also prepared with the crack positioned away from the interface to determine the effect of notch position on fracture behaviour. The effect of strength mismatch on the crack tip opening displacement fracture toughness parameter of the joints has been evaluated. Crack initiation, crack growth, and crack deviation processes have been examined and fracture resistance curves (R curves) constructed for the joints. These results were used to explain the influence of mechanical heterogeneity of the joints and interlayer thickness on fracture behaviour.
Development of flash butt welding monitor for improvement of quality control in production of steel car wheels
Authors: Syrek G. J. , Doan T. M.
Published: February 2003

An investigation was conducted to identify the defects occurring in steel car wheels for an automotive component manufacturer. That work led to the development of the present flash butt welding (FBW) monitor. The FBW monitor acquires the weld current, voltage, and electrode displacement during the production of a wheel and compares measurements with preset values to determine the integrity of the weld. In addition to checking the weld parameters, the monitor statistically analyses the characteristic of every electrical cycle of the weld current and voltage for abnormalities. Weld parameters and other statistical quantities are recorded and can be used for post-process analysis of production data. The monitor has been employed over a long period of time in a production plant and its capability for use in FBW quality assessment and improvements has been proven.
Novel method for cooling plasma welding torch head
Authors: Wu P. S. , Chao Y. Y. , Chiou Y. J. , Lin Y. C.
Published: February 2003

The performance of a design using swirling flow with a U shaped return passage to cool the tip of a plasma arc torch is numerically investigated. The new cooling scheme is first compared with the cooling design of a Nippon Steel plasma torch. Using a hypothetical swirling flow of different vortex angles but the same coolant flowrate and external heating boundary conditions as for the Nippon Steel torch, the flow and temperature fields for both torches were analysed using a computational fluid dynamics package and the results were compared. The results show that the present cooling scheme not only provides a more axisymmetric temperature field, but also results in lower averaged surface temperatures. Using a swirling flow generator implemented upstream of the tip of the U shaped region, numerical results indicate that improved cooling performance can be achieved with only a slight increase in coolant pumping head when compared with the cooling design for the Nippon Steel torch.
Analysis of residual stress in carbon steel weldment incorporating phase transformations
Authors: Cho S.-H. , Kim J.-W.
Published: February 2003

The welding process, incorporating rapid heating and cooling, generates distortion and residual stress in weldments. Welding distortion and residual stress in welded structures can result in problems such as dimensional inaccuracies during assembly and raise concerns regarding safety during service. Therefore, accurate prediction and reduction of residual stress are critical in improving the quality of a weldment. In the present paper a new method of analysis is proposed to predict welding residual stress by considering solid phase transformations during the welding process. This method is applied to two cases, involving medium carbon steel and low carbon steel respectively. The analysis of medium carbon steel revealed the presence of compressive residual stress due to martensite formation when phase transformation was considered. However, in low carbon steel the residual stress obtained considering the effect of phase transformation did not differ significantly from that obtained when phase transformation was ignored.
Effects of mechanical constraints on angular distortion of welding joints
Authors: Park J.-U. , Lee H.-W. , Bang H.-S.
Published: February 2003

During the manufacture of steel structures, welding deformations have undesirable effects on the accuracy of assembly, external appearance, buckling strength, fatigue strength, etc. In particular, in such large steel structures as ships, welding deformations produced during assembly lead to variations in dimensions which require considerable time and expense for repair, resulting in a decrease in productivity. In the present work a new method is presented to derive the constraint coefficient from the degree of angular deformation caused by welding, as measured experimentally by varying the shape of welded joints and the magnitude of constraints and from analysis results obtained via the elastic finite element method. The equivalent load was then calculated using this constraint coefficient. The validity of the numerical analysis involved in this new method was confirmed by its agreement with the experimental results. Regarding the effects of the constraints in relation to the shape of the welded joints, when the constraint coefficients are not considered for butt welding, the quantity of deformation predicted by analysis is greater than that produced in experiments and consequently butt welding is strongly affected by the constraints. However, for fillet welding, the quantity of deformation is hardly affected regardless of constraint coefficient considerations.
Ductile—brittle transition of steel electron beam weld metal in small punch test
Authors: Gai X. , Sato Y. S. , Kokawa H. , Ichikawa K.
Published: February 2003

Toughness evaluation of narrow high energy beam welds via the conventional Charpy V notch (CVN) impact test is not always successful because cracks often deviate from the fusion zone into the heat affected or unaffected base metal zones. The small punch (SP) test was applied to electron beam welds of a 490 MPa strength steel to evaluate the toughness by measuring the ductile-brittle transition temperature (DBTT). The steel was electron beam welded using various heat inputs and the welds were examined via CVN and SP tests at 40-298 K. The SP DBTTs obtained from the SP energy showed a linear correlation with the CVN DBTTs. The load-deflection curves during the SP tests and the fractography of SP tested specimens indicated the existence of ductile-brittle transitions. The results suggest that the SP test can be used to predict the DBTTs of electron beam welds, which cannot be accomplished via the conventional CVN impact test.
Effect of nickel with chromium on microstructure and toughness of heat affected zone in low carbon steel
Authors: Eroğlu M.
Published: February 2003

In the present work, the effects of nickel with chromium and of varying heat input on the microstructure and toughness of the grain coarsened heat affected zone (GCHAZ) of a low carbon steel were investigated. In the welding experiments, low carbon steel specimens having five different combinations of nickel and chromium content (0·9Ni–0·3Cr, 1·9Ni–0·8Cr, 2·8Ni–1·3Cr, 3·8 Ni–1·7Cr, and 4·9Ni–2·1Cr, all wt%) were welded using a submerged arc welding process with heat inputs of 0·5, 1, and 2 kJ mm-1. Following welding, the microstructure, hardness, and toughness of the GCHAZs were investigated. From the results, attempts were made to establish a relationship between heat input, nickel and chromium contents, microstructure, hardness, and toughness of the GCHAZ. Charpy impact testing and microstructural observation showed that, for a heat input of 0·5 kJ mm-1, nickel plus chromium contents in the range 1·9Ni–0·8Cr to 4·9Ni–2·1Cr promoted the formation of martensite, thereby producing lower toughness values. It was subsequently found that, taking into consideration the microstructure, hardness, and toughness of the GCHAZ, an intermediate heat input (1 kJ mm-1) gave higher toughness values for all nickel and chromium contents. However, it was observed that satisfactory toughness values could not be obtained by varying the heat input for the 3·8Ni–1·7Cr and 4·9Ni–2·1Cr steels.
Effect of laser spot weld energy and duration on melting and absorption
Authors: Fuerschbach P. W. , Eisler G. R.
Published: February 2003

To facilitate pulse Nd–YAG laser spot weld development, it is common practice to adjust the pulse energy, duration, and focus spot size. An accurate understanding of the effect of these parameters on melting, weld appearance, and heat input is thus required. Calorimetric measurements of the net heat input to 304 stainless steel workpieces for laser spot welds have been completed. A pulse Nd–YAG laser was used with varying pulse energies from 1 to 5·5 J, and pulse durations of 2·2 and 7·0 ms. Measurements showed the absorption for spot welds produced using the pulsed Nd–YAG laser to vary from 38 to 67% and to be relatively insensitive to beam intensity. Analysis of the continuous point source equation for conduction heat flow in solids was used to predict the weld size for the pulse energy and duration measured in the experiment. Calculations of the weld pool volume from the weld metallography were used to determine the melting for each spot weld. Comparisons of the measured weld size with the three-dimensional model predicted size indicated that the observed weld pools are larger than is expected from the measured workpiece energy. Analysis of the experimental data and the theoretical model has revealed a substantial increase in melting for short duration pulses versus long duration pulses of the same energy. The benefit of laser spot welding parameter optimisation is hence indicated.
Characteristics of hollow cathode arc as welding heat source: Arc characteristics and melting properties
Authors: Nishikawa H. , Yoshida K. , Ohji T. , Suita Y. , Masubuchi K.
Published: February 2003

A feasibility study has been conducted to determine whether a hollow cathode arc (HCA) can be used for a welding heat source in space, that is high vacuum and microgravity conditions. The HCA method enables the arc discharge to form under low pressure conditions by purging a small amount of gas through the centre of the hollow cathode. The characteristics of HCAs under low pressure conditions have been experimentally investigated, in particular the melting properties and voltage-current characteristics. Results show that the penetration profile and arc characteristics of the HCA method are sensitive to process parameters such as gas flowrate, arc length, and inner diameter of the electrode, and that the penetration in HCA melting is extremely deep under the conditions of low gas flowrate and long arc length.
Tensile yield load solutions for centre cracked bilayer (clad) plates with and without repair welds
Authors: Motarjemi A. K. , Koçak M.
Published: February 2003

Bilayer metallic structural components in the form of clad plates are often used owing to their superior environmental and mechanical properties. During the service life of these components, cracks or cracklike defects may be developed in the clad layer and may grow into the substrate. To repair the damaged regions, local repair welding techniques are often used. The presence of this repair welded part may affect the deformation behaviour, and hence yield load level, of the structure. Therefore, in the present paper, new analytical tensile yield load solutions for centre cracked clad steel plates (austenitic cladding on a ferritic substrate) with a repair weld have been developed and these provide good agreement with experimental results. Additionally, a previously reported tensile yield load expression for a centre cracked clad plate (without a repair weld) has also been verified using the experimental results.
Predicting steady state dilution in multipass hardfacing overlays - geometric approach
Authors: Francis J. A.
Published: February 2003

A geometric model of steady state dilution in multipass hardfacing overlays deposited via self shielded flux cored arc welding is presented. In this model the steady state bead profile in cross-section and the shape of the fusion line are represented by parabolic functions. Without requiring empirical corrections, the model accurately predicts the steady state dilutions of eight high chromium white iron overlays that were each deposited on steel substrates under different welding conditions. Estimates for the surface smoothness of the overlay, or the peak to valley ripple, are also obtained from the model. Thus, the model provides the necessary information to predict the steady state composition and geometry of a multipass hardfacing overlay. Reference can then be made to studies relating composition and geometry to abrasive wear resistance in order to complete the link between the welding parameters used to deposit the overlay and its subsequent wear performance.
Vision based neurofuzzy logic control of weld pool geometry
Authors: Luo H. , Devanathan R. , Wang J. , Chen X. , Sun Z.
Published: February 2003

The geometry of the weld pool contains accurate, instantaneous information about welding quality. Thus, weld pool sensing and control plays a significant role in automated arc welding. Previous studies have focused on inferring penetration through models and controlling penetration by various methods, such as adaptive control, model based fuzzy logic, etc. In the present work, a weld pool imaging system employing a LaserStrobe (tradename) high shutter speed camera is used to obtain contrasting images and eliminate arcing interference. Two image processing tools based on edge detection and connectivity analysis extract online information about the weld pool length and width. A neurofuzzy control system elicited from both human experience and experimental results has been developed to control the welding current and welding speed in real time based on changes in weld pool dimensions. Closed loop control of welding speed is used to achieve desirable weld pool geometry.
Prediction of multiwire submerged arc weld bead shape using neural network modelling
Authors: Ridings G. E. , Thomson R. C. , Thewlis G.
Published: February 2003

A significant problem faced by today's welding engineers is the need to relate welding parameters to the quality of the finished weld. This is usually achieved by experience, and necessitates many experimental trials, eventually leading to optimal welding parameters. Important characteristics in the evaluation of linepipe seam weld quality are the weld bead shape and size, which can have a significant effect on the microstructure and mechanical properties of the weldment through heat flow effects. The present paper describes the application of neural network techniques to the prediction of the outer diameter weld bead shape for three wire, single pass per side, submerged arc, linepipe seam welds, using the weld process parameters as inputs. Novel methods of digitisation of weld macrostructures produced under different experimental conditions, used in the training of the neural network, are discussed. The contribution of a particular welding process parameter (input relevance) to the variation in the final weld bead shape is also considered. It is shown that it is possible to develop a neural network model that will predict the shape of an entire weld bead, without the necessity to assume it to be symmetric, with a relatively high degree of confidence.
Defining populations: a key step in identifying spatial and temporal scales
Authors: Menzie Charles A , Wickwire W Theodore
Published: February 2003

The scale at which ecological risk assessors frame their analyses can be driven by a number of considerations. In many cases, the selection of the scale is among the most important decisions within the `problem-formulation’ phase of the ecological risk characterization. The scale of a risk characterization is often defined based on ownership boundaries, ecological, or habitat boundaries and/or physical and hydrogeological boundaries (e.g., watersheds). With increasing value being placed on consideration of spatial scales in risk characterization, the need to define a scale that balances analytical and ecological realities is imperative. Defining the spatial scale based on the scale of a population offers the risk assessor the opportunity to improve the ecological relevance of the risk characterization. Arriving at a single operational definition of a population would be difficult and not appropriate because of the variability in sites, issues, and management goals; however, we can begin to review operational definitions and establish analytical frameworks by which to select the appropriate, site-specific scale within the problem-formulation phase. Defining a scale based on a combination of ecological and site ownership considerations and the inclusion of habitat quality in the assessment of scale can improve the power and relevance of the problem formulation and risk characterization. In this analysis, we assess methods for incorporating spatial considerations into risk analyses, beginning with developing an understanding of the context of a site within the larger landscape. Clearly defining the scale of an assessment including the operational definition of populations is an important step in the problem formulation. Within a site or landscape, the scale may be refined further based on the percentage of the land within the scale of the analysis that provides habitat for a given species.
Importance of Minimal Residual Disease Testing During the Second Year of Therapy for Children With Acute Lymphoblastic Leukemia
Authors: Marshall Glenn M. , Haber Michelle , Kwan Edward , Zhu Ling , Ferrara Daniella , Xue Chengyuan , Brisco Michael J. , Sykes Pamela J. , Morley Alexander , Webster Boyd , Dalla Pozza Luciano , Waters Keith , Norris Murray D.
Published: February 2003

Purpose: A high level of minimal residual disease (MRD) after induction chemotherapy in children with acute lymphoblastic leukemia (ALL) is an indicator of relative chemotherapy resistance and a risk factor for relapse. However, the significance of MRD in the second year of therapy is unclear. Moreover, it is unknown whether treatment intervention can alter outcome in patients with detectable MRD.

Patients and Methods: We assessed the prognostic value of MRD testing in bone marrow samples from 85 children at 1, 12, and 24 months from diagnosis using clone-specific polymerase chain reaction primers designed to detect clonal antigen receptor gene rearrangements. These children were part of a multicenter, randomized clinical trial, which, in the second year of treatment, compared a 2-month reinduction-reintensification followed by maintenance chemotherapy with standard maintenance chemotherapy alone.

Results: MRD was detected in 69% of patients at 1 month, 25% at 12 months, and 28% at 24 months from diagnosis. By univariate analysis, high levels of MRD at 1 month, or the presence of any detectable MRD at 12 or 24 months from diagnosis, were highly predictive of relapse. Multivariate analysis showed that MRD testing at 1 and 24 months each had independent prognostic significance. Intensified therapy at 12 months from diagnosis did not improve prognosis in those patients who were MRD positive at 12 months from diagnosis.

Conclusion: Clinical outcome in childhood ALL can be predicted with high accuracy by combining the results of MRD testing at 1 and 24 months from diagnosis.
Interaction of the Growth Hormone Receptor with Cytokine-Induced Src Homology Domain 2 Protein in Rat Adipocytes
Authors: Du Ling , Frick G. Peter , Tai Lih-Ruey , Yoshimura Akihiko , Goodman H. Maurice
Published: February 2003

GH stimulates the phosphorylation of tyrosine residues in the GH receptor (GHR), Janus kinase 2 (JAK2), and other signaling proteins in a transient manner that subsides within 1 h. To assess the possible roles of cytokine-induced Src homology domain 2 (SH2) (CIS/SOCS) proteins in these transient responses, we studied the expression and disposition of CIS/SOCS proteins in rat adipocytes, a physiological target of GH action. A tyrosine-phosphorylated protein that appears to be the GHR was coprecipitated from extracts of GH-treated adipocytes with α-CIS. In contrast, no tyrosine-phosphorylated adipocyte proteins were recovered after immunoprecipitation with α-SOCS3, although coprecipitation of GHR with SOCS3 was readily detected in extracts of 3T3-F442A fibroblasts. Interaction of GHR with CIS peaked between 2 and 10 min after adipocytes were treated with GH, when tyrosine phosphorylation of the GHR was maximal. By 60 min after GH, tyrosine phosphorylation of the GHR declined to very low levels, and its interaction with CIS was reduced correspondingly. Proteasome inhibitors prevented the decline in tyrosine-phosphorylated GHR and prolonged interaction of GHR and CIS for at least 1 h. These findings demonstrate the interaction of CIS with the GHR in vivo and suggest that CIS may enhance degradation of the receptor by a proteasomal pathway.
The Porcine Sodium/Iodide Symporter Gene Exhibits an Uncommon Expression Pattern Related to the Use of Alternative Splice Sites not Present in the Human or Murine Species
Authors: Selmi-Ruby Samia , Watrin Chantal , Trouttet-Masson Severine , Bernier-Valentin Françoise , Flachon Virginie , Munari-Silem Yvonne , Rousset Bernard
Published: February 2003

The sodium/iodide symporter (NIS) is a membrane protein mediating the active transport of iodide into the thyroid gland. NIS, expressed by human, rat, and mouse thyrocytes, is encoded by a single transcript. We identified NIS mRNA species of 3.5 and 3 kb in porcine thyrocytes. Because porcine thyrocytes in primary culture is a widely used experimental system for thyroid iodide metabolism, we further examined the origin and the function of the porcine NIS (pNIS) transcripts. We generated a porcine thyroid cDNA library from which four different clones, pNIS-D, F, J, and ΔJ were isolated. pNIS-D encodes a protein of 643 amino acids highly homologous to the human, rat, and mouse NIS. pNIS-F and J differ from each other and from pNIS-D in their C-terminal part. pNIS-ΔJ lacks a six-amino-acid segment within the putative transmembrane domain 10. Transiently expressed in Cos-7 cells, the four pNIS-cDNAs led to the synthesis of proteins targeted at the plasma membrane and conferred perchlorate-sensitive iodide uptake activities to Cos-7 cells, except pNIS-ΔJ, which was devoid of activity. PNIS-D probably derives from the 3.5-kb transcript and pNIS-F, J, and ΔJ from the 3-kb transcript. The relative abundance of pNIS-D, F, and J transcripts in porcine thyrocytes was about 60%, 35%, and 5%, respectively; the ΔJ transcript was not present in detectable amount. By comparing porcine NIS genomic and cDNA sequences, splice donor and acceptor sites accounting for the generation of pNIS-F, J, and ΔJ transcripts were identified. None of the combinations of alternative splice sites found in the pig was present in the human, rat or mouse NIS gene. Our data show that porcine NIS gene, contrary to the NIS gene from other species, gives rise to splice variants leading to three active and one inactive NIS proteins.
Spatial and cellular localization of calcium-dependent protease (CDP II)inAllomyces arbuscula
Authors: Ojha Mukti , Barja Francisco
Published: February 2003

Immunogold labeling of calcium-dependent neutral protease II (CDPII) with specific antibodies in near median longitudinal ultrathin sections of Allomyces arbuscula showed that the enzyme is predominantly localized in the growing hyphal and rhizoidal apices. The tips in both cell type had more enzyme than the distal regions and showed a gradient distribution. Labeling of the ultrathin sections and western blot analysis of purified subcellular fractions showed that CDPII is mainly cytosolic. Catalytic activity of the enzyme measured with synthetic substrate (Bz-Arg-pNA) showed that 90% of its activity is present in the soluble fraction, although a small amount is associated with the nuclei (0.2%), plasma membranes (0.7%) and microsomes (3.9%). This association is discussed in the context of the functional role of the enzyme and its possible localized activation. Western blot analysis of the crude extract and indirect immunofluorescence of the fixed permeabilized hypahe after treatment with CDPII showed that theα-tubulin is a specific target of the enzyme.
Cadherin function probed by laser tweezer and single molecule fluorescence in vascular endothelial cells
Authors: Baumgartner Werner , Schütz Gerhard J. , Wiegand Johannes , Golenhofen Nikola , Drenckhahn Detler
Published: February 2003

In endothelial monolayers agonist-induced influx of Ca2+ and activities of the actin cytoskeleton have been shown to be crucially involved in regulation of barrier properties. By laser tweezer application we demonstrated that the strength of adhesion of VE-cadherin-coated microspheres to the surface of cultured endothelial monolayers is significantly reduced by treatment with two well-established permeability-increasing compounds,cytochalasin D and the Ca2+-ionophore A23187, which shows that both compounds directly affect cadherin-mediated adhesion. Cytochalasin D and A23187 caused considerable decay of F-actin (30-60%). Stabilisation of F-actin by jasplakinolide completely blocked drug-induced weakening of bead adhesion showing that attenuation of cadherin-cadherin trans-interaction induced by cytochalasin D and A23187 depends largely on downregulation of F-actin. Single molecule fluorescence microscopy demonstrated that drug-induced weakening of adhesion is accompanied by an increase in lateral mobility of cadherins as well as by dispersal of cadherin-enriched plasmalemmal microdomains. However,the lifetime (≈700 milliseconds, koff≈1.4 second–1) and apparent on-rate of cadherin trans-interaction(relative frequency of binding) remained unchanged in response to cytochalasin D and A23187 indicating that cadherin-mediated adhesion is not modulated by inside-out changes of the affinity but, rather, appears to be controlled by actin-dependent tethering and compartmentalization of cadherins.
Distinct caveolae-mediated endocytic pathways target the Golgi apparatus and the endoplasmic reticulum
Authors: Le Phuong U. , Nabi Ivan R.
Published: February 2003

Internalization of autocrine motility factor (AMF) into the endoplasmic reticulum is sensitive to the cholesterol-extracting reagent methyl-β-cyclodextrin, inhibited by the dynamin-1 K44A mutant and negatively regulated by caveolin-1. Thus, AMF internalization requires a caveolae-mediated endocytic pathway. Similarly, we show here that endocytosis of cholera toxin (CTX) in NIH-3T3 fibroblasts is inhibited by adenoviral expression of the dynamin-1 K44A mutant but only partially by expression of the clathrin hub. Treatment with methyl-β-cyclodextrin and overexpression of caveolin-1, but not the clathrin hub, selectively diminishes CTX endocytosis to the Golgi apparatus but not to endosomes. CTX is therefore targeted via a caveolin-1-regulated caveolae-mediated pathway to the Golgi. Disruption of Golgi-, caveosome- or endosome-mediated trafficking with brefeldin A, nocodazole or a 20°C temperature block, respectively, inhibit CTX endocytosis to the Golgi but do not affect AMF delivery to the endoplasmic reticulum. Following an incubation of only five minutes in the presence of the clathrin hub, AMF and CTX are not cointernalized, and AMF is delivered to the AMF-R-positive smooth ER. The internalization of both ligands is nevertheless sensitive to the tyrosine kinase inhibitor genistein, confirming that they are both internalized via caveolae/raft pathways. Two distinct caveolae-mediated endocytic pathways therefore exist, including a novel direct pathway to the ER from the plasma membrane.
An integrated fuzzy decision support system for multicriterion decision-making problems
Authors: Chan F T S , Chan H K , Chan M H
Published: February 2003

In order to compete effectively in today's rapidly changing world economy, decision making should be made fast and accurate, especially when many tangible and intangible factors are considered together. Making decisions to implement advanced manufacturing technologies (AMTs) is a good example. However, not all AMT implementations are successful because most of the conventional investment justification criteria are built on tangible factors, such as cost reduction, only. Intangiabl long-term benefits such as improvement in quality, increase in flexibility, and fast delivery are always disregarded. The objective of this paper is to present an integrated approach, which incorporates different approaches (e.g. strategic, economic and analytic evaluations) for assessing the benefits among several alternative proposals, such as implementing AMT, by a fuzzy multicriterion decision-making method.
Performance evaluation of cryogenically treated tungsten carbide cutting tool inserts
Authors: Seah K H W , Rahman M , Yong K H
Published: February 2003

This paper presents an overview of the effects of various subzero thermal treatments on the tool life and wear characteristics of cobalt-bonded tungsten carbide cutting tool inserts. The inserts were subjected to six different conditions of treatment, namely (a) as-received, (b) quenching treatment, (c) cryogenic treatment, (d) cryogenic treatment followed by tempering, (e) cold treatment and (f) cold treatment followed by tempering. It was found that the inserts that had undergone the latter four conditions of treatment exhibited significantly greater tool life and wear resistance at higher cutting speeds, as well as an overall increased resistance to chipping. Microstructural analysis was used to explain the observed phenomena.
Estimation of in-process cutting constants in ball-end milling
Authors: Zheng C M , Junz Wang J -J
Published: February 2003

Two methods are presented for the estimation of tangential, radial and axial cutting coefficients for the shearing and ploughing mechanisms from a single set of cutting forces in ball-end milling. These estimation methods are based upon the invertibility of the analytical milling force model, which considers both the shearing and the ploughing mechanisms by incorporating their respective cutting constants in the local force model. The periodic milling forces are established as the convolution integral of the differential local cutting forces and their Fourier coefficients are derived and expressed in a matrix expression as a linear function of the unknown cutting constants in terms of cutting conditions and cutter geometry. This linear expression thus leads to a systematic formulation of the estimation methods allowing the six unknown cutting constants to be determined from the measured milling forces. The first method uses the first harmonic forces as the source signal while the second method extracts the six cutting constants from the average force as well as the first harmonics. Limitations of both estimation methods are discussed. The consistency and accuracy of the estimated cutting constants are confirmed by the experimental results.
Multi-constraint optimization and cutting conditions selection in process planning turning operations with modern chip breaker tools
Authors: Armarego E J A , Ostafiev D
Published: February 2003

It has long been recognized that the selection of cutting conditions in process planning should optimize the economic performance of machining operations although it appears that common practice favours the use of ‘recommended’ cutting conditions which are known to be non-optimal. This practice seems to be partly due to the difficulties in establishing equations for the many technological machining performance measures and partly due to the complex nature and slow progress made in developing reliable multi-constraint optimization analyses. This paper presents multi-constraint optimization analyses and computer aided strategies for selecting the ‘optimal’ feeds and speeds in single-pass rough turning operations. The optimization, based on criteria typified by the minimum time and cost per component and suitable for the newer coated lathe tools with in-built chip breaker groove designs, incorporates chip breaking constraints for turning on computer numerical control (CNC) lathes. Despite the complexity of the analyses, clearly denned strategies that guarantee the global optimal solutions have been developed. Extensive simulation studies have highlighted the considerable economic benefits of using ‘optimal’ rather than ‘recommended’ cutting conditions, the potential for increased benefits from improved chip control and tool magazine designs and the need for technological performance equations as well as optimization analyses for the wide spectrum of machining operations for use in modern process planning.
Numerical and experimental study of the heat transfer process in friction stir welding
Authors: Song M , Kovacevic R
Published: February 2003

A mathematical model to describe the detailed three-dimensional transient heat transfer process in friction stir welding (FSW) is presented. This work is both theoretical and experimental. An explicit central differential scheme is used in solving the control equations, the heat transfer phenomena during the tool penetrating, the welding and the tool-removing periods that are studied dynamically. The heat input from the tool shoulder is modelled as a frictional heat and the heat from the tool pin is modelled as a uniform volumetric heat generated by the plastic deformation near the pin. The temperature variation during the welding is also measured to validate the calculated results. The calculated results are in good agreement with the experimental data.
Numerical simulation of heat transfer and fluid flow in a double-sided gas-tungsten arc welding process
Authors: Dong H , Gao H , Wu L
Published: February 2003

Double-sided arc welding powered by a single power supply is a new type of welding process developed recently at the University of Kentucky. Experiments show that this process has advantages over conventional single-sided arc welding in enhancing penetration, minimizing distortion, improving solidification structure and welding aluminium without the necessity of using filler metal for cracking prevention. In this paper, a three-dimensional transient numerical model is developed for the heat transfer and fluid flow in double-sided gas-tungsten arc welding, including flat-position welding and vertical-up position welding. Based on a non-uniform staggered grid system, the governing equations are solved numerically using the SIMPLEC algorithm. The roles of the surface tension gradient, electromagnetic force and buoyancy force in determining the fluid flow and weld penetration are analysed and compared with those in the conventional arc welding process. The computed weld geometry is compared with experimental results and it is found that the computational results agree with the experimental results with reasonable accuracy.
On the correlation of statistical and automatic process control
Authors: Harris J
Published: February 2003

A process control strategy is proposed based upon the twin themes of statistical and automatic process control. The main categories of product fault are identified and related to the capabilities of statistical and automatic control. Statistical control is supported by process fault information from a process-specific fault tree analysis, which provides the basis for a corrective intervention protocol. Application is discussed in terms of fuzzy automatic control, which offers a greater generality than conventional automatic control modelling. Prior publications that fuzzify statistical control zones are arguably incomplete in the application of logic propositions and also in the identification of process faults. The present work proposes a general strategy, which may be adapted to specific processes. Both control by variables and control by attributes may be included within this treatment.
Prediction of the wear profile of a roll groove in rod rolling using an incremental form of wear model
Authors: Kim D H , Lee Y , Yoo S J , Choo W Y , Kim B M
Published: February 2003

A model for predicting the wear profile of the ductile cast iron roll during rod (or bar) rolling is proposed using Archard's wear equation. Archard's wear equation was reformulated as an incremental form and the hardness of the roll was expressed as a function of rolling time under a high temperature. The wear profile of the roll is calculated at each deformation step by consideration of relative sliding velocity and normal roll pressure at contact area. The coefficients required in the proposed wear model have been obtained using the high-temperature wear tester of pin-on-disc type.

A three-dimensional finite element analysis coupled with the proposed wear model has been carried out for the oval-round pass rolling sequence widely used in present continuous rod (or bar) rolling mills. To describe the deformation behaviour of material at the roll/material interface better, a contact-searching algorithm that can be applied efficiently to the finite element mesh was also suggested.

The results showed that, for an oval groove, the maximum wear occurs at the centre part of the roll and, for a round groove, at the shoulder area of the roll. The wear profiles moves to the spread direction of workpiece (i.e. roll axis direction) as well as the direction of roll centre as the production (tonnage) increases. The proposed wear model might be used for adjusting the gap (pass height) of rolls to set up a suitable rolling schedule for keeping dimensional tolerance of the product and avoid catastrophic failure of rolls after rolling a characteristic tonnage.
Analysis and finite element simulation of tube expansion in a rectangular cross-sectional die
Authors: Hwang Y-M , Chen W-C
Published: February 2003

The objectives of this paper are to propose a simple analytical expression, which can be used easily in a manufacturing plant to estimate the forming pressure, and to explore the plastic deformation behaviour of the tubes during the hydraulic expansion process in a rectangular cross-sectional die. At first, when considering the sticking condition, analytical expressions using the thin-walled and thick-walled theorems are proposed to determine the forming pressures needed to hydroform a circular tube into a rectangular cross-section with a desired corner radius. Then a series of finite element simulations of tube expansion are carried out to compare the simulation results of forming pressures with those from the proposed analytical expressions. The flow pattern of the tube during hydraulic expansion in a rectangular die is also examined. The effects of the friction coefficient between the die and the tube upon the thickness variations at certain positions during expansion and the thickness distributions after the expansion process are discussed.
Wheelbase filtering and automobile suspension tuning for minimizing motions in pitch
Authors: Sharp R S
Published: February 2003

The rear to front stiffness tuning of the suspension system of a car is discussed, through reference to a half-car pitch plane mathematical model. New results relating to the frequency responses of the bouncing (heaving) and pitching motions of the carbody in following sinusoidal terrain are used to show more clearly than before that the pitch minimization mechanism, known since Olley's observations in the early 1930s, involves interference between the responses to the front and rear axle inputs. It is shown that interference with respect to the rotational motion implies reinforcement with respect to the translational motion, and vice versa. Phasor diagrams are constructed for particular cases to illustrate the mechanics. At higher vehicle speeds, Olley tuning is shown to bring a marked advantage in pitch suppression with very little disadvantage in terms of body accelerations. At lower speeds, not only does the pitch tuning bring with it large vertical acceleration penalties but also the suspension stiffnesses implied are impractical from an attitude control standpoint. The results shown can be employed to guide new suspension designs. Alternatively, corresponding computations can be carried out for new cases of interest, since they are easy to do and rapid.
An investigation into a string-stable vehicle following control strategy for stop-and-go cruise control
Authors: Yi K , Park Y
Published: February 2003

A string-stable vehicle following control strategy for stop-and-go (SG) cruise control is presented in this paper. Stop-and-go cruise control systems should be designed such that a string of the controlled vehicle is string stable in addition to every vehicle in a string of SG cruise control vehicles having to track any bounded acceleration and velocity profile of its preceding vehicle with a bounded spacing and velocity error. An optimal vehicle following control law based on the infor-mation of the following distance (clearance) and its velocity relative to the vehicle ahead (relative velocity) has been used, and string stability analysis has been based on the control law and constant time gap spacing policy. The minimum time gap for string stability has been obtained on the basis of the analysis, and the results have been verified via computer simulations. Simulation studies have been carried out using a multivehicle simulation package validated using vehicle test data. It has been shown that the minimum time gap for string stability from the string stability analysis is a good estimate to give a quantitative value for a string-stable SG cruise controller.