Geometric error measurement is required to evaluate the grade of the manufactured gears. Due to the complexity of the spiral bevel gear, direct measurement with the physical part has been conducted in a very limited way. In this paper, we present an indirect measurement based on the virtual gears model (VGM), obtained by NUBS fitting of the surface points measured by CMM (coordinate measuring machine). By comparing the VGM with CAD model (soft-master model), various errors such as tooth profile error and tooth trace error can be automatically measured. The developed method is simple and robust without requiring a special measuring device, and hence it can be applied for the industrial practice as a means for measuring the tooth profile and tooth trace errors which cannot be measured by the conventional method. Further, the model-based method can be incorporated on the advanced CNC controller based on the new CAM–CNC interface scheme of STEP-NC [STEP (standard for transfer and exchange of product model data) based data model for CAM and CNC interface] as an on-line inspection module. Algorithmic details together with experimental validation results are given.

Geometric error measurement of spiral bevel gears using a virtual gear model for STEP-NC

The Office of Graduate Studies has verified and approved the abovenamed committee members iii To my dear wife Tianran iv AKNOWLEDGEMENTS The author would like to extend his gratitude to his advisor, Dr. Chuck Zhang, for his guidance and support during the preparation of this dissertation. Special thanks are extended to Dr.

Dimension variation prediction and control for composites

Introduction
Mitral Valve (MV) 3D structural data can be easily obtained using standard transesophageal echocardiography (TEE) devices but quantitative pre- and intraoperative volume analysis of the MV is presently not feasible in the cardiac operation room (OR). Finite element method (FEM) modelling is necessary to carry out precise and individual volume analysis and in the future will form the basis for simulation of cardiac interventions.

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Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry.

In this study, the cutting errors in the tooth profile of the spur gears which are manufactured by end mill according to radial cutting method in three-axis CNC milling machine are investigated. According to this method, a mathematical approach in order to investigate the cutting errors of the tooth profile is presented. Then, mathematical expressions determining the error quantity in the tooth profile curve are derived by using this approach, and a programme is developed in the MATLAB. Parameters such as module (m), tooth number (N), pressure angle (∅) and cutting angle (α
 m
 ) in the programme are changed, and the cutting errors of the involute tooth profile according to the obtained results are interpreted graphically. As a result, it is seen that the cutting errors in the involute curve increase according to increments of m, N, ∅ and α
 m
 .

A study on cutting errors in the tooth profiles of the spur gears manufactured in CNC milling machine

Background
Finite element method (FEM) analysis for intraoperative modeling of the left ventricle (LV) is presently not possible. Since 3D structural data of the LV is now obtainable using standard transesophageal echocardiography (TEE) devices intraoperatively, the present study describes a method to transfer this data into a commercially available FEM analysis system: ABAQUS©.

/pdf/feasibility-of-rapid-and-automated-importation-of-3d-5730byaoof.pdf

Feasibility of rapid and automated importation of 3D echocardiographic left ventricular (LV) geometry into a finite element (FEM) analysis model.

A method for inspecting a helical gear using a coordinate measuring machine (CMM) is proposed. In the method, the coordinates of a large number of points on the tooth surface of the gear are measured at random using a CMM. The method is based on the idea that the pitch error, profile error, pressure angle error, and spiral angle error can be calculated from the measured coordinates because the information on various errors of the gear is included in the measured coordinates. For calculation of each error, the tooth surface is described as a function of each error item and then the values for the items are estimated from all of the measured coordinates by the method of least squares. The difference between the estimated value for the item and the corresponding design value is the error of the item. From the results of experiments, it is clarified that each error of a helical gear can be estimated using a widespread CMM instead of a specially designed measuring machine for gears.

Measurement of Helical Gear Using Coordinate Measuring Machine.

A method for measuring a pillion type cutter using a coordinate measuring machine is proposed. In this method, the cutting edge profile of the cutter is indirectly measured as the intersecting curve between the flank of tool and the cutting face. Left and right side flanks of the cutter are considered to be the tooth surfaces of two different involute helical gears. The coordinates of many points on the tooth surface and the face are measured using a coordinate measuring machine. The tooth surface and the face are estimated from the measured data by the method of least squares. The cutting edge profile is calculated from the estimated tooth surface and the face. The cutting edge is moved helically and it forms the tooth surface of the actual imaginary gear. A pressure angle of this gear can be calculated. Pressure angle error of the pinion type cutter is that of the imaginary gear.

/pdf/measurement-of-pinion-type-cutter-using-coordinate-measuring-hjj7dihjxd.pdf

Measurement of Pinion Type Cutter Using Coordinate Measuring Machine

Measurement of Screw-Compressor Rotor Using Coordinate Measuring Machine

Removal of invasive plant species is the first step to restoring the invaded ecosystems. The soil microbial biomass and extracellular enzyme activities were measured in Moso bamboo (Phyllostachys edulis) pure forest (completely invasion), invasive P. edulis removal forest (secondary succession 5 years after clear cutting), and the evergreen broadleaved forest (no invasion) in Tianmu Mountain. The results showed that compared with P. edulis pure forest, invasive P. edulis removal significantly increased the contents of soil organic carbon (SOC), nitrate nitrogen, available phosphorus and potassium, as well as microbial biomass carbon (MBC) and microbial biomass phosphorus (MBP), while significantly decreased microbial biomass nitrogen (MBN). The activities of α-glucosidase (AG), β-glucosidase (BG), leucine aminopeptidase (LAP) and phenol oxidase (POX) in the forest with removal of invasive P. edulis were significantly higher than those in P. edulis pure forest, while invasive P. edulis removal did not change the activities of cellodisaccharide hydrolase (CBH), β-N-acetyl-glucosaminopeptidase (NAG), acid phosphatase (ACP) and peroxidase (PER). Furthermore, the activities of AG, BG and LAP were positively correlated with SOC and MBC, while the increase in POX activity was positively correlated with soil nitrate content. In addition, MBC, MBN and MBP, and activities of AG, BG, NAG, LAP and ACP in P. edulis removal forest forest were significantly higher than those in evergreen broadleaved forests. Taken together, the removal of invasive P. edulis could increase soil nutrient contents, microbial biomass and extracellular enzyme activities, thus could be considered as an effective way to restore the invaded forests. Our results provide important theoretical basis for controlling P. edulis invasion in subtropical forests.

Zongxian Liu

Papers

Measurement of Helical Gear Using Coordinate Measuring Machine.

Measurement of Pinion Type Cutter Using Coordinate Measuring Machine

Measurement of Screw-Compressor Rotor Using Coordinate Measuring Machine

[Effects of the removal of invasive Moso bamboo on soil microbial biomass and enzyme activities in subtropical forests].