Off-axis quantitative phase imaging processing using CUDA: toward real-time applications

We demonstrate real time off-axis Quantitative Phase Imaging (QPI) using a phase reconstruction algorithm based on NVIDIA’s CUDA programming model. The phase unwrapping component is based on Goldstein’s algorithm. By mapping the process of extracting phase information and unwrapping to GPU, we are able to speed up the whole procedure by more than 18.8× with respect to CPU processing and ultimately achieve video rate for mega-pixel images. Our CUDA implementation also supports processing of multiple images simultaneously. This enables our imaging system to support high speed, high throughput, and real-time image acquisition and visualization

Single-port laparoscopic sacrospinous ligament suspension via the natural vaginal cavity (SvNOTES) for pelvic prolapse: The first feasibility study

ObjectiveThis study aims to investigate the feasibility and short-term efficacy of single-port laparoscopic-assisted transvaginal natural cavity endoscopic sacrospinous ligament suspensions (SvNOTES).MethodsA total of 30 patients diagnosed with anterior or/and middle pelvic organ prolapse Stages III and IV underwent natural vaginal cavity (SvNOTES), and 30 patients who underwent conventional sacrospinous ligament (SSLF) were used as a control group. The operation time, blood loss, postoperative POP-Q score, length of hospital stay, and complications were compared between the two groups.ResultsThe operation time for SvNOTE was (60 ± 13) min, which was longer than (30 ± 15) min for SSLF (P = 0.04). However, the bleeding amount in SvNOTE was 29.44 ± 2.56, significantly lower than that in the SSLF group (80 ± 10; P = 0.02), and the postoperative hospital stay in the SvNOTE group was (4 ± 2) days, longer than (3 ± 1) days in SSLF (P = 0.02). However, there were no intraoperative complications in the SvNOTE group, whereas one ureteral injury occurred in the SSLF group; in addition, the postoperative POP-Q score was significantly better in the SvNOTE group than that in the SSLF group with increasing time (P < 0.001).ConclusionCompared with SSLF, single-port laparoscopic sacrospinous ligament suspension via the natural vaginal cavity is visualized, greatly improving the success rate of sacrospinous ligament fixation, with less blood loss and fewer complications, arguably a safer and minimally invasive surgical approach

Automatic Structural Synthesis of Planar Mechanisms and Its Application to Creative Design

In order to find a systematic approach to aid the creative design of mechanisms, this thesis proposes a unified structural synthesis method for planar kinematic chains and mechanisms with simple and multiple joints, characterized by effectiveness, automation and human-machine interaction, and develops the atlas databases containing all the topological graphs for these kinematic chains and mechanisms with different numbers of links, classified by their structural characteristics. Based on the classified atlas databases, the creative design of several kinds of mechanisms is also conducted to verify the usefulness of the method. The overall structure of the thesis is as follows: (1) In chapter 2, the representation models of planar kinematic chains with simple joints, multiple joints and geared joints are presented and the relationships between these models are revealed. (2) In chapter 3, the relationships of contracted graphs of planar non-fractionated kinematic chains and their link assortment arrays are revealed first. Then a fully-automatic method for the synthesis of the contracted graphs of planar non-fractionated kinematic chains is proposed. With the method, the complete families of non-fractionated contracted graphs and of valid contracted graphs with up to eight basic loops and all possible degrees of freedom are synthesized and obtained for the first time. (3) In chapter 4, a general method is proposed to synthesize planar non-fractionated kinematic chains and mechanisms based on the obtained contracted graphs. The method is fully-automatic and designer-friendly, and planar non-fractionated kinematic chains and mechanisms with up to 19 links are synthesized. Moreover, the classified atlas databases for these kinematic chains and mechanisms are also established. (4) In chapter 5, based on the structure characteristics of fractionated kinematic chains, a general synthesis equation of planar fractionated kinematic chains is proposed first. Then an automatic method is proposed to synthesize planar fractionated kinematic chains by the combination of planar non-fractionated kinematic chains, and the whole family of planar fractionated kinematic chains with up to seven basic loops is synthesized for the first time. (5) In chapter 6, based on the new bicolor topological graph and its inter-convertible characteristics with that of simple joint kinematic chains, an automatic method is proposed to synthesize multiple joint kinematic chains from simple joint kinematic chains and their classified atlas databases. The whole family of multiple joint kinematic chains with up to 16 links is synthesized for the first time and corresponding classified atlas databases are also established. (6) In chapter 7, based on the structural synthesis and classified atlas databases of kinematic chains with simple and multiple joints, a creative design method is proposed to obtain all the feasible mechanisms for a specified task from the topological graphs in the classified atlas databases subject to design constraints. The creative design of road tractors, hydraulic robots and forging manipulators is conducted as examples, and a number of novel mechanisms are obtained for the first time together with the widely used ones

Design of a Centrifugal Force-Based Speed Sensor for Downhole Turbodrills

Turbodrill is an important type of drilling tool. Rotating speed is a key parameter to measure and control the efficiency of a turbodrill. Therefore, it is necessary to measure the rotating speed when a turbodrill is working under a well. However, current speed measurement devices and sensors cannot meet the requirements of the on-site downhole conditions due to many factors, including inadequate sealing, signal interference, difficult installation, and theoretical limitations. To break the aforementioned bottleneck, a new speed sensor used for turbodrills is designed based on the centrifugal force theory. In more detail, the measurement of the speed is performed based on a functional relation between the rotating speed and the centrifugal force of the turbodrill. Besides, the sensor was tested both in-lab and on-site. The test results illustrate that the measurement error is within ±4%, which meets the practical on-site conditions

The Development and Test of a Sensor for Measurement of the Working Level of Gas–Liquid Two-Phase Flow in a Coalbed Methane Wellbore Annulus

Coalbed methane (CBM) is one kind of clean-burning gas and has been valued as a new form of energy that will be used widely in the near future. When producing CBM, the working level within a CBM wellbore annulus needs to be monitored to dynamically adjust the gas drainage and extraction processes. However, the existing method of measuring the working level does not meet the needs of accurate adjustment, so we designed a new sensor for this purpose. The principle of our sensor is a liquid pressure formula, i.e., the sensor monitors the two-phase flow patterns and obtains the mean density of the two-phase flow according to the pattern recognition result in the first step, and then combines the pressure data of the working level to calculate the working level using the liquid pressure formula. The sensor was tested in both the lab and on site, and the tests showed that the sensor’s error was ±8% and that the sensor could function well in practical conditions and remain stable in the long term

Theory of Parallel Mechanisms

This book contains mechanism analysis and synthesis. In mechanism analysis, a mobility methodology is first systematically presented. This methodology, based on the author's screw theory, proposed in 1997, of which the generality and validity was only proved recently,  is a very complex issue, researched by various scientists over the last 150 years. The principle of kinematic influence coefficient and its latest developments are described. This principle is suitable for kinematic analysis of various 6-DOF and lower-mobility parallel manipulators. The singularities are classified by a new point of view, and progress in position-singularity and orientation-singularity is stated. In addition, the concept of over-determinate input is proposed and a new method of force analysis based on screw theory is presented. In mechanism synthesis, the synthesis for spatial parallel mechanisms is discussed, and the synthesis method of difficult 4-DOF and 5-DOF symmetric mechanisms, which was first put forward by the author in 2002, is introduced in detail. Besides, the three-order screw system and its space distribution of the kinematic screws for infinite possible motions of lower mobility mechanisms are both analyzed