scholarly journals Research on geometric error modelling and decoupling of machine tool based on NURBS projection curve

2021 ◽  
Author(s):  
WEI LI ◽  
Yanyan Feng ◽  
Shihui Zhang ◽  
Wei Zuo
Keyword(s):  
Machine Tool ◽  
High Efficiency ◽  
Rotation Axis ◽  
Geometric Error ◽  
Two Dimensional ◽  
Dimensional Plane ◽  
Error Recognition ◽  
Low Efficiency ◽  
Feed Axis ◽  
Five Axes

Abstract As a geometric measuring instrument of machine tool, double ball bar (DBB) instrument can effectively identify the geometric error of machine tool. In the existing literature, DBB mostly uses the two-dimensional circle as the identification trajectory to identify the geometric error continuously, and the most efficient way of single recognition is still in two-dimensional plane. Aiming at the low efficiency of DBB spatial geometric error recognition, the recognition range of DBB is extended from two-dimensional plane to spatial hemisphere. A method of space recognition and decoupling based on NURBS projection curve is proposed in this paper. The error decoupling of feed axis and rotation axis is realized in an experiment. The identification method has the characteristics of high efficiency, no secondary assembly and avoiding interference. It can decouple all the five axes in hemispherical space at one time and get the effective solution.

An Improvement Geometric Error Identification Method of CNC Machine Tool Based on Double Ball Bar

2014 ◽  
Vol 496-500 ◽  
pp. 1516-1521
Author(s):  
Qiang Cheng ◽  
Zhuo Qi ◽  
Kai Li ◽  
Li Gang Cai ◽  
Dong Lu
Keyword(s):  
Machine Tool ◽  
Recognition Algorithm ◽  
Geometric Error ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Error Identification ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Error Recognition ◽  
Better Than

The double ball bar is widely used because it can quickly, easily and cost-effectively detect and evaluate the accuracy of CNC machine tools. But since the error recognition algorithm based on the double ball bar ignores the quadratic item, its recognition accuracy would be reduced. In this paper, an improved CNC verticality error and position error identification formula, combined with the machine tool error model to deduce a new error recognition model of double ball bar measurement is proposed. It can be drawn that the accuracy of the model are better than the existing methods because it keeps the second item in the derivation process of the model.

scholarly journals CHROMOSOMAL BASIS OF THE MEROZYGOSITY IN A PARTIALLY DIPLOID MUTANT OF PNEUMOCOCCUS

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 667-678
Author(s):  
Mary Lee S Ledbetter ◽  
Rollin D Hotchkiss
Keyword(s):  
High Efficiency ◽  
Point Mutations ◽  
Resistant Mutant ◽  
Chromosomal Marker ◽  
Structural Abnormality ◽  
C Cells ◽  
Wild Type ◽  
Chromosomal Locus ◽  
Low Efficiency ◽  
Derivatives Of

ABSTRACT A sulfonamide-resistant mutant of pneumococcus, sulr-c, displays a genetic instability, regularly segregating to wild type. DNA extracts of derivatives of the strain possess transforming activities for both the mutant and wild-type alleles, establishing that the strain is a partial diploid. The linkage of sulr-c to strr-61, a stable chromosomal marker, was established, thus defining a chromosomal locus for sulr-c. DNA isolated from sulr-c cells transforms two mutant recipient strains at the same low efficiency as it does a wild-type recipient, although the mutant property of these strains makes them capable of integrating classical "low-efficiency" donor markers equally as efficiently as "high efficiency" markers. Hence sulr-c must have a different basis for its low efficiency than do classical low efficiency point mutations. We suggest that the DNA in the region of the sulr-c mutation has a structural abnormality which leads both to its frequent segregation during growth and its difficulty in efficiently mediating genetic transformation.

scholarly journals A Brief Review on Solvent-Free Synthesis of Zeolites

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 788
Author(s):  
Jinlin Mei ◽  
Aijun Duan ◽  
Xilong Wang
Keyword(s):  
High Efficiency ◽  
Raw Materials ◽  
Solvent Free ◽  
High Yield ◽  
Control Synthesis ◽  
Mechanical Mixing ◽  
Synthesis Mechanism ◽  
Wastewater Pollution ◽  
Low Efficiency ◽  
Solvent Free Synthesis

The traditional hydrothermal method to prepare zeolite will inevitably use a large amount of water as a solvent, which will lead to higher autogenous pressure, low efficiency, and wastewater pollution. The solvent-free method can be used to synthesize various types of zeolites by mechanical mixing, grinding, and heating of solid raw materials, which exhibits the apparent advantages of high yield, low pollution, and high efficiency. This review mainly introduces the development process of solvent-free synthesis, preparation of hierarchical zeolite, morphology control, synthesis mechanism and applications of solvent-free methods. It can be believed that solvent-free methods will become a research focus and have enormous industrial application potential.

scholarly journals Inflight Transmission of COVID-19 Based on Experimental Aerosol Dispersion Data

2021 ◽  
Author(s):  
Zhaozhi Wang ◽  
Edwin R Galea ◽  
Angus Grandison ◽  
John Ewer ◽  
Fuchen Jia
Keyword(s):  
High Efficiency ◽  
Face Mask ◽  
Generation Rate ◽  
Aviation Industry ◽  
Filtration System ◽  
Dispersion Data ◽  
Low Probability ◽  
Meal Service ◽  
Low Efficiency ◽  
Aerosol Dispersion

Abstract Background An issue of concern to the travelling public is the possibility of in-flight transmission of COVID-19 during long- and short-haul flights. The aviation industry maintains that the probability of contracting the illness is small based on reported cases, modelling and data from aerosol dispersion experiments conducted on-board aircraft. Methods Using experimentally derived aerosol dispersion data for a B777–200 aircraft and a modified version of the Wells-Riley equation we estimate inflight infection probability for a range of scenarios involving quanta generation rate and face mask efficiency. Quanta generation rates were selected based on COVID-19 events reported in the literature while mask efficiency was determined from the aerosol dispersion experiments. Results The MID-AFT cabin exhibits the highest infection probability. The calculated maximum individual infection probability (without masks) for a 2-hour flight in this section varies from 4.5% for the ‘Mild Scenario’ to 60.2% for the ‘Severe Scenario’ although the corresponding average infection probability varies from 0.1% to 2.5%. For a 12-hour flight, the corresponding maximum individual infection probability varies from 24.1% to 99.6% and the average infection probability varies from 0.8% to 10.8%. If all passengers wear face masks throughout the 12-hour flight, the average infection probability can be reduced by approximately 73%/32% for high/low efficiency masks. If face masks are worn by all passengers except during a one-hour meal service, the average infection probability is increased by 59%/8% compared to the situation where the mask is not removed. Conclusions This analysis has demonstrated that while there is a significant reduction in aerosol concentration due to the nature of the cabin ventilation and filtration system, this does not necessarily mean that there is a low probability or risk of in-flight infection. However, mask wearing, particularly high-efficiency ones, significantly reduces this risk.

Modeling and Identification of Geometric Error Based on Screw Theory

2014 ◽  
Vol 941-944 ◽  
pp. 2219-2223 ◽  
Author(s):  
Guo Juan Zhao ◽  
Lei Zhang ◽  
Shi Jun Ji ◽  
Xin Wang
Keyword(s):  
Machine Tool ◽  
Laser Interferometer ◽  
Screw Theory ◽  
Geometric Error ◽  
New Method ◽  
Geometric Errors ◽  
Volumetric Error ◽  
B Spline ◽  
The Individual

In this paper, a new method is presented for the identification of machine tool component errors. Firstly, the Non-Uniform Rational B-spline (NURBS) is established to represent the geometric component errors. The individual geometric errors of the motion parts are measured by laser interferometer. Then, the volumetric error for a machine tool with three motion parts is modeled based on the screw theory. Finally, the simulations and experiments are conducted to confirm the validity of the proposed method.

Reconfigurable data driven virtual machine tool: Geometric error modeling and evaluation

2015 ◽  
Vol 10 ◽  
pp. 120-130 ◽  
Author(s):  
Ronnie R. Fesperman ◽  
Shawn P. Moylan ◽  
Gregory W. Vogl ◽  
M. Alkan Donmez
Keyword(s):  
Machine Tool ◽  
Virtual Machine ◽  
Geometric Error ◽  
Error Modeling ◽  
Data Driven ◽  
Virtual Machine Tool
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