scholarly journals Erratum to “Uniform Coverage of Fibres over Open-contoured Free-form Structure Based on Arc-length Parameter” [Chinese Journal of Aeronautics 21(2008)571-577]

2009 ◽  
Vol 22 (3) ◽  
pp. 256
Author(s):  
Wang Xiaoping ◽  
An Luling ◽  
Zhang Liyan ◽  
Zhou Laishui
Keyword(s):  
Free Form ◽  
Arc Length ◽  
Chinese Journal ◽  
Uniform Coverage

Generation of Noncircular Bevel Gears With Free-Form Tooth Profile and Curvilinear Tooth Lengthwise

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Fangyan Zheng ◽  
Lin Hua ◽  
Xinghui Han ◽  
Dingfang Chen
Keyword(s):  
Screw Theory ◽  
Mapping Method ◽  
Tooth Profile ◽  
Bevel Gear ◽  
Free Form ◽  
Arc Length ◽  
Screw Axis ◽  
Bevel Gears ◽  
Generating Method ◽  
Instant Screw Axis

Noncircular bevel gear is applied to intersecting axes, realizing given function of transmission ratio. Currently, researches are focused mainly on gear with involute tooth profile and straight tooth lengthwise, while that with free-form tooth profile and curvilinear tooth lengthwise are seldom touched upon. Based on screw theory and equal arc-length mapping method, this paper proposes a generally applicable generating method for noncircular bevel gear with free-form tooth profile and curvilinear tooth lengthwise, covering instant screw axis, conjugate pitch surface, as well as the generator with free-form tooth profile and curvilinear tooth lengthwise. Further, the correctness of the proposed method is verified through illustrations of computerized design.

Open Architecture Controllers for Machine Tools, Part 2: A Real Time Quintic Spline Interpolator

1998 ◽  
Vol 120 (2) ◽  
pp. 425-432 ◽  
Author(s):  
Fu-Chung Wang ◽  
P. K. Wright
Keyword(s):  
Real Time ◽  
Tool Path ◽  
Interpolation Method ◽  
Tool Path Generation ◽  
Open Architecture ◽  
Free Form ◽  
Path Generation ◽  
Arc Length ◽  
Quintic Spline ◽  
Data Points

In Part 2 of this two-part paper, we describe a new quintic spline interpolator for real time trajectory generation during free form curve machining on the Open Architecture machine tool platform described in Part I. The research provides new capabilities for advanced CAD/CAM systems. Complicated curves and shapes designed in a CAD system are usually represented by a set of discrete data points. Subsequently, for manufacturing by a CAM system, these data points need to be converted into tool paths for machining. Therefore, the paper presents a new interpolation method that interpolates the designated data points with a quintic spline curve for real-time tool path generation. The resultant curve, generated by the proposed interpolation method, is nearly arc-length parametrized and has C3 continuity. The near arc-length parametrization property makes the real time generation of the reference commands of the cutting tool path easier. The C3 continuity guarantees the smooth motion of continuous speed, acceleration and even jerk during the machining. The combined properties of this new interpolation method enable a new quintic spline interpolator to be developed for real time tool path generation.

Piecewise B-Spline Tool Paths With the Arc-Length Parameter and Their Application on High Feed, Accurate CNC Milling of Free-Form Profiles

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Zezhong C. Chen ◽  
Maqsood A. Khan
Keyword(s):  
Tool Path ◽  
Free Form ◽  
Arc Length ◽  
Cnc Milling ◽  
B Spline ◽  
Tool Paths ◽  
High Feed ◽  
Genuine Solution ◽  
Cnc Controller ◽  
Very High

To conduct B-spline curve machining, first, B-spline tool paths with feed rates are planned; and second, the B-spline interpolator generates tool trajectories in real-time based on the paths fed into the computer numerically controlled (CNC) controller. Currently, the paths are often planned geometrically with a nonarc-length parameter. Literally, the interpolator can process B-spline paths with the arc-length parameter well, while it sometimes is challenged to work with the nonarc-length parameterized B-spline paths. As a consequence, it is difficult to ensure high accuracy of the tool trajectories in B-spline machining in terms of their corresponding paths; especially, if the feed is very high, smooth tool kinematics cannot be well maintained. To root out these problems, a new type of tool path—piecewise B-spline tool paths with the arc-length parameter—is first proposed in this work. Given a B-spline path with a nonarc-length parameter, it is accurately converted into a B-spline path with an arc-length parameter before sending it into the CNC controller. Furthermore, if the prescribed feed rate is very high and the arc-length parameterized B-spline path is disqualified, it is split into pieces represented with distinct arc-length parameterized B-spline paths in different feed rates. The main advantage of these piecewise paths is that they can eliminate the problems encountered by the existing B-spline interpolator with input of nonarc-length parameterized B-spline paths. Therefore, the piecewise arc-length parameterized B-spline paths are a genuine solution to high feed-and-accuracy B-spline machining.

Approximately Arc-Length Parametrized C3 Quintic Interpolatory Splines

1999 ◽  
Vol 121 (3) ◽  
pp. 430-439 ◽  
Author(s):  
F.-C. Wang ◽  
P. K. Wright ◽  
B. A. Barsky ◽  
D. C. H. Yang
Keyword(s):  
High Speed ◽  
Interpolation Method ◽  
Free Form ◽  
Precision Machining ◽  
Arc Length ◽  
Quintic Spline ◽  
Line Segments ◽  
Spline Curve ◽  
Straight Line ◽  
Data Points

A quasi-global interpolation method that fits a quintic spline curve to a set of designated data points is described in this paper. The resultant curve has several important features. First, the curve is smooth with C3 continuity and has no unwanted oscillations. Second, the generated quintic spline is “optimally” parametrized; that is, the curve is parametrized very closely to its arc length. In addition, with the interpolation method, straight line segments can be preserved to generate a quintic spline of hybrid curve segments. The properties of C3 continuity and the “near arc length” parametrization have direct applications to trajectory planning in robotics and the development of new types of machine tool controllers for high speed and precision machining. The encapsulation of straight line segments enhances the capability for the shape designers to design more complicated shapes, including free form curves and straight line segments in a uniform way.

scholarly journals Uniform Coverage of Fibres over Open-contoured Freeform Structure Based on Arc-length Parameter

2008 ◽  
Vol 21 (6) ◽  
pp. 571-577 ◽  
Author(s):  
Wang Xiaoping ◽  
An Luling ◽  
Zhang Liyan ◽  
Zhou Laishui
Keyword(s):  
Arc Length ◽  
Uniform Coverage

The visual perception of arc length on a real surface

1997 ◽  
Author(s):  
J. Farley Norman ◽  
Joseph S. Lappin ◽  
Hideko F. Norman
Keyword(s):  
Visual Perception ◽  
Real Surface ◽  
Arc Length

Minimal contribution of cell-bound antibodies to the immunoscintigraphy of inflamed joints with 99mTc-anti-CD4 monoclonal antibodies

2002 ◽  
Vol 41 (03) ◽  
pp. 129-134 ◽  
Author(s):  
A. Wolski ◽  
E. Palombo-Kinne ◽  
F. Wolf ◽  
F. Emmrich ◽  
W. Becker ◽  
...  
Keyword(s):  
T Cells ◽  
Monoclonal Antibodies ◽  
Synovial Membrane ◽  
In Vitro Release ◽  
Peritoneal Macrophages ◽  
Lymphoid Organs ◽  
Whole Body ◽  
Free Form ◽  
Ankle Joints

Summary Aim: The cellular joint infiltrate in rheumatoid arthritis patients is rich in CD4-positive T-helper lymphocytes and macrophages, rendering anti-CD4 monoclonal antibodies (mAbs) suitable for specific immunoscintigraphy of human/ experimental arthritis. Following intravenous injection, however, mAbs are present both in the free form and bound to CD4-positive, circulating monocytes and T-cells. Thus, the present study aimed at analyzing the relative contribution of the free and the cell-bound component to the imaging of inflamed joints in experimental adjuvant arthritis (AA). Methods: AA rat peritoneal macrophages or lymph node T-cells were incubated in vitro with saturating amounts of 99mTc-anti-CD4 mAb (W3/25) and injected i.v. into rats with AA. Results: In vitro release of 99mTc-anti-CD4 mAb from the cells was limited (on average 1.57%/h for macrophages and 0.84%/h for T-cells). Following i.v. injection, whole body/joint scans and tissue measurements showed only negligible accumulation of radioactivity in inflamed ankle joints (tissue: 0.22 and 0.34% of the injected activity, respectively), whereas the radioactivity was concentrated in liver (tissue: 79% and 71%, respectively), kidney, and urinary bladder. Unlike macrophages, however, anti-CD4 mAb-coated T-cells significantly accumulated in lymphoid organs, the inflamed synovial membrane of the ankle joints, as well as in elbow and knee joints. Conclusion: While the overall contribution of cell-bound mAbs to the imaging of arthritic joints with anti-CD4 mAbs is minimal, differential accumulation of macrophages and T-cells in lymphoid organs and the inflamed synovial membrane indicates preferential migration patterns of these 2 cell populations in arthritic rats. Although only validated for 99mTc-anti-CD4 mAbs, extrapolation of the results to other anticellular mAbs with similar affinity for their antigen may be possible.

Immunoreactivity of Tissue Plasminogen Activator and of Its Inhibitor Complexes

1989 ◽  
Vol 61 (03) ◽  
pp. 409-414 ◽  
Author(s):  
M Rånby ◽  
G Nguyen ◽  
P Y Scarabin ◽  
M Samama
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Degradation Products ◽  
Gel Filtration ◽  
Free Form ◽  
Enzyme Linked Immunosorbent Assay ◽  
Plasma Samples ◽  
Significant Difference ◽  
Tissue Plasminogen ◽  
Pai 1

SummaryAn enzyme linked immunosorbent assay (ELISA) based on goat polyclonal antibodies against human tissue plasminogen activator (tPA) was evaluated. The relative immunoreactivity of tPA in free form and tPA in complex with inhibitors was estimated by ELISA and found to be 100, 74, 94, 92 and 8l% for free tPA and tPA in complex with PAI-1, PAI-2, α2-antiplasmin and C1-inhibitor, respectively. Addition of tPA to PAI-1 rich plasma resulted in rapid and total loss of tPA activity without detectable loss of ELISA response, indicating an immunoreactivity of tPA in tPA/PAI-1 complex of about l00%. Three different treatments of citrated plasma samples (acidification/reneutralization, addition of 5 mM EDTA or of 0.5 M lysine) prior to determination by ELISA all resulted in increased tPA levels. The fact that the increase was equally large in all three cases along with good analytical recovery of tPA added to plasffi, supported the notion that all tPA antigen present in plasma samples is measured by the ELISA. Analysis by ELISA of fractions obtained by gel filtration of plasma from a patient undergoing tPA treatment identified tPA/inhibitor complexes and free tPA but no low molecular weight degradation products of tPA. Determinations of tPA antigen were made at seven French clinical laboratories on coded and randomized plasma samples with known tPA antigen content. For undiluted samples there was no significant difference between the tPA levels found and those known to be present. The between-assay coefficient of variation was 7 to 10%. In conclusion, the ELISA appeared suited for determination of total tPA antigen in human plasma samples.

The Different Forms of Antithrombin III in Serum

1977 ◽  
Vol 38 (02) ◽  
pp. 0494-0503 ◽  
Author(s):  
D. S Pepper ◽  
D Banhegyi ◽  
J. D Cash
Keyword(s):  
Molecular Weight ◽  
Affinity Chromatography ◽  
Human Serum ◽  
Degradation Product ◽  
Antithrombin Iii ◽  
Gel Filtration ◽  
Free Form ◽  
Polymeric Form ◽  
At Iii ◽  
Human Thrombin

SummaryAntithrombin III (AT III) complexes were isolated from human serum by affinity chromatography and gel filtration. In the first step of the preparation, using heparin-agarose chromatography, we observed that the complexed form of AT III bound less strongly to the gel than the free form and that about half of the AT III was free. With further purification a 2.5 × 105 molecular weight complex was isolated. Using 125I labelled human thrombin, this complex was radioactive indicating the presence of thrombin. Only in a synthetic thrombin-AT III system was a 9 × 104 molecular weight complex detected, but not in serum. These facts suggest that in serum AT III complexes may exist in a polymeric form. Also, an AT III antigen derived from the original AT III molecule, but not complexed, was isolated which may be a degradation product.Abbreviations used: AT-III, antithrombin III. Hepes, N-2-Hydroxyethylpiperazine-N-2-Ethanesulphonic acid.

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