A Fast Image Guide Registration Supported by Single Direction Projected CBCT

Image registration is an important research topic in medical image-guided therapy, which is dedicated to registering the high-dose imaging sequences with low-dose/faster means. Registering computer tomography (CT) scanning sequences with cone beam computer tomography (CBCT) scanning sequences is a typical application and has been widely used in CBCT-guided radiotherapy. The main problem is the difference in image clarity of these two image sequences. To solve this problem, for the single projection image sequence matching tasks encountered in medical practice, a novel local quality based curved section encoding strategy is proposed in this paper, which is called the high-quality curved section (HQCS). As an optimized cross-section regularly encoded along the sequence of image, this curved section could be used in order to solve the matching problem. Referencing the independent ground truth provided by medical image physicians, with an experiment combined with the four most widely used indicators used on image registration, matching performance of HQCS on CT/CBCT datasets was tested with varying clarity. Experimental results show that the proposed HQCS can register the CT/CBCT effectively and outperforms the commonly used methods. Specifically, the proposed HQCS has low time complexity and higher scalability, which indicates that the application enhanced the task of diagnosis

Research and Application of Polycarboxylic Acid Water Reducer with Different Molecular Weight

In this paper, a polycarboxylic water reducing agent was synthesized by using Methylallyl polyethylene glycol (HPEG) with molecular weight of 1200, 2400, 2800 and 3400 under the same conditions, C80 concrete tests were performed on these four molecular weight superplasticizers, verify the effect of different molecular weight polycarboxylic acid water reducer in C80 pumping concrete, finally, a kind of low molecular weight polycarboxylic acid water reducer with viscosity reducing effect in high-grade concrete is obtained, which can promote pumping of high-grade concrete

A Fast Image Guide Registration Supported by Single Direction Projected CBCT

Image registration is an important research topic in medical image-guided therapy, which is dedicated to registering the high-dose imaging sequences with low-dose/faster means. Registering computer tomography (CT) scanning sequences with cone beam computer tomography (CBCT) scanning sequences is a typical application and has been widely used in CBCT-guided radiotherapy. The main problem is the difference in image clarity of these two image sequences. To solve this problem, for the single projection image sequence matching tasks encountered in medical practice, a novel local quality based curved section encoding strategy is proposed in this paper, which is called the high-quality curved section (HQCS). As an optimized cross-section regularly encoded along the sequence of image, this curved section could be used in order to solve the matching problem. Referencing the independent ground truth provided by medical image physicians, with an experiment combined with the four most widely used indicators used on image registration, matching performance of HQCS on CT/CBCT datasets was tested with varying clarity. Experimental results show that the proposed HQCS can register the CT/CBCT effectively and outperforms the commonly used methods. Specifically, the proposed HQCS has low time complexity and higher scalability, which indicates that the application enhanced the task of diagnosis

Parameter Analysis of Wall Thickness of Cured-in-Place Pipe Linings for Semistructured Rehabilitation of Concrete Drainage Pipe

Frequent accidents caused by underground pipeline damage are a widespread societal concern. Trenchless rehabilitation methods, particularly cured-in-place pipe (CIPP) lining, are increasingly used for pipeline repair with great success. Existing research is mainly concerned with practical improvements in rehabilitation and evaluating the performance of rehabilitation. In this study, the model of corroded buried concrete pipeline that had been rehabilitated with CIPP was established using numerical methods, and the Mesh-based parallel-Code Coupling Interface (MpCCI) was used to investigate multifield coupling effects of soil pressure, traffic load, and fluid-structure interactions. Moreover, the influences of corrosion depth, corrosion width, traffic load, cover depth, and water quantity on CIPP wall thickness were compared and analyzed. The result shows that maximum principal stress and vertical displacement of pipeline markedly decreased after CIPP rehabilitation, and thus the new CIPP can carry loads in a deteriorated pipe. Stress and displacement of the composite pipe liner were positively correlated with corrosion depth and negatively correlated with corrosion width. Increase in traffic load rapidly increases von Mises stress of CIPP, and increase in cover depth rapidly increases maximum principal stress of pipeline. Water flow has little effect on the pipe liner, and flow capacity increases slightly after CIPP rehabilitation. CIPP wall thickness was positively correlated with corrosion depth, traffic load, cover depth, and water quantity and negatively correlated with corrosion width

Research and Application of Polycarboxylic Acid Water Reducer with Different Molecular Weight

In this paper, a polycarboxylic water reducing agent was synthesized by using Methylallyl polyethylene glycol (HPEG) with molecular weight of 1200, 2400, 2800 and 3400 under the same conditions, C80 concrete tests were performed on these four molecular weight superplasticizers, verify the effect of different molecular weight polycarboxylic acid water reducer in C80 pumping concrete, finally, a kind of low molecular weight polycarboxylic acid water reducer with viscosity reducing effect in high-grade concrete is obtained, which can promote pumping of high-grade concrete

Experimental Study on Eccentric Compressive Performance of Concrete Column Strengthened with CFRP Grid Reinforced ECC Matrix

Carbon-fiber-reinforced polymer (CFRP) grid and engineered cementitious composite (ECC) were combined in this study to strengthen concrete columns. The influences of the number of layers, the overlap length of CFRP grids, and the eccentricity on the bearing capacity and rigidity of reinforced concrete columns were determined. The results show that the principal failure of the reinforced column was debonding of external ECC from FRP grids at the compressive area, edges, or sides. Significant enhancement in the ultimate bearing capacity and rigidity of eccentrically loaded columns was observed after they were externally reinforced by CFRP grids and ECC; such enhancement increased with the number of reinforced layers. Eccentricity made little difference to the enhancement rate of bearing capacity when the number of reinforced layers was the same. At different eccentricities, the composite layers at the tensile area and the compressive area had different contributions to the bearing capacity. An effective bond and efficient stress transfer could be ensured as long as the overlap length between CFRP grids reached 120 mm

Shack–Hartmann Wavefront Sensing Based on Four-Quadrant Binary Phase Modulation

Aiming at the problem that it is difficult for the conventional Shack–Hartmann wavefront sensor to achieve high-precision wavefront reconstruction with low spatial sampling, a kind of Shack–Hartmann wavefront sensing technology based on four-quadrant binary phase modulation is proposed in this paper. By introducing four-quadrant binary phase modulation into each subaperture, the technology is able to use an optimization algorithm to reconstruct wavefronts with high precision. The feasibility and effectiveness of this method are verified at extreme low spatial frequency by a series of numerical simulations, which show that the proposed method can reliably reconstruct wavefronts with high accuracy with rather low spatial sampling. In addition, the experiment demonstrates that with a 2 × 2 microlens array, the four-quadrant binary phase-modulated Shack–Hartmann wavefront sensor is able to achieve approximately 54% reduction in wavefront reconstitution error over the conventional Shack–Hartmann wavefront sensor

Numerical and Experimental Investigation of the Effect of Traffic Load on the Mechanical Characteristics of HDPE Double-Wall Corrugated Pipe

The high-density polyethylene (HDPE) double-wall corrugated pipe, which is a kind of flexible pipe, is widely used in municipal drainage networks. The characteristics of the surrounding soil and pipe bed, pipe cover depth, backfill compaction, type of pavement and pavement design, and traffic loads are some of the major factors that affect the stress and deformation of pipes. In this study, the ABAQUS 3D finite element model was used to analyze the influence of backfill compactness, traffic loads, diameter, and hoop stiffness on the mechanical characteristic of an HDPE pipe under traffic loads. A series of full-scale tests were carried out to verify the validity of the simulation results. For the conditions tested, the results showed the following: (1) the Von-Mises stress of the pipe was mainly determined by the earth pressure at the crown, and the stress caused by backfill compaction increased significantly but had a short duration and limited impact on the pipe; (2) traffic load alone had little influence on the mechanical behavior of the pipe: while under the action of the loose backfill in contact with the pipe, the pipes were more sensitive to the traffic load response; (3) the fluctuations in the Von-Mises stress of the pipe mainly depended on the magnitude and speed of the traffic load; (4) for pipes with a small diameter, non-compacted backfill easily caused stress concentration in the pipe, while the degree of backfill compaction had almost the same effect on the distribution of stress for pipes with different hoop stiffness

Experimental and Numerical Study on Mechanical Analysis of Buried Corroded Concrete Pipes under Static Traffic Loads

Concrete pipes are widely used in municipal drainage projects. Corrosion is a common issue affecting concrete pipes, causing leakage of pipes, environmental pollution, and road collapse. It is necessary to study the mechanical properties of corroded concrete pipes. To investigate in depth the influence of corrosion depths, corrosion widths, traffic loads, and cover depths, on mechanical characteristics of buried corroded concrete pipes under static traffic loads, a series of full-scale tests were carried out. Then, a three-dimensional finite element model of buried corroded concrete pipes under traffic loads is established based on ABAQUS. Results showed that the inside of the pipe wall is more vulnerable to damage than the outside. The stress and strain of a corroded pipe is significantly larger than that of an uncorroded pipeline. The corrosion has a great influence on the stress and strain of the corroded area. The maximum principal stress and circumferential strain at corroded area increase with increasing of corrosion depth. The stress and strain first increases rapidly (0–10°), and then decreases rapidly (10–45°), then finally decreases slowly (45–180°) with an increase of corrosion width. In addition, the greater cover depth or increasing traffic load causes a rapid increase in both circumferential strain and the maximum principal stress