Installation Accuracy Research Articles

IMAGING ANALYSIS OF ACETABULAR CUP POSITIONS IN TOTAL HIP ARTHROPLASTY FOR ADULTS WITH ACETABULAR DYSPLASIA

To investigate the influence of the degree of acetabular deformity and the learning-curve on the acetabular cup positions in total hip arthroplasty (THA) for adults with developmental dysplasia of hip (DDH). Between January 2008 and December 2015, 130 patients (144 hips) with DDH underwent primary THA, and the clinical data were analyzed retrospectively. Fifty-three patients (59 hips) were admitted before 2012, and 77 patients (85 hips) were treated after 2012. There were 32 males and 98 females, aged from 31 to 83 years (mean, 61). Unilateral replacement was performed in 116 cases and bilateral replacement in 14 cases. Of 144 hips, 48 hips were rated as Crowe type I, 57 hips as type II, and 39 hips as type of III/IV. The standard pelvic radiograph was taken within 1 week after operation. The mediCAD software was adopted to measure the angle of anteversion and abduction, bony coverage, and the distance between true rotating center and optimal rotating center to the connection of teardrops and the horizontal distance between two centers to evaluate the qualified rate of acetabular cup positions. Compared with the patients with the same type in 2013-2015 group, the anteversion angle and qualified rate of acetabular cup position significantly decreased in patients with Crowe I (P<0.05); the horizontal distance significantly increased and qualified rate of acetabular cup position significantly decreased in patients with Crowe II (P<0.05); and the anteversion angle significantly decreased and the horizontal distance significantly increased in patients with Crowe III/IV (P<0.05) in 2008-2012 group. But no significant difference was shown in the other indexes (P>0.05). In all Crowe types, the vertical distance between the true rotating center and the optimal rotating center increased with the degree of acetabular deformity in both 2008-2012 group and 2013-2015 group, showing significant difference (P<0.05), but no significant difference was found in the other indexes (P>0.05). For adults with acetabular dysplasia, there are high potential risks for unsatisfactory acetabular cup positions during primary THA. So it is necessary to evaluate acetabular deformities and to sum up operative experience so as to improve the accuracy of cups installation.

Evaluating the Effect of a Mechanical Adjunct to Improve the Installation of Child Restraint Systems to Vehicles

Objectives: We explored if an alternative CRS design that utilized a mechanical adjunct to amplify the force applied to the adult seat belt (intervention CRS) results in more accurate and secure attachment between the CRS and the vehicle compared to similar CRS models that use LATCH or the existing adult seat belt. We conducted three separate studies to address this question and additionally explored: (1) the contribution of prior CRS installation experience (Study 1), (2) the value-added of CRS labeling (Study 2), and (3) paper-based vs. video instructions (Study 3).Methods: In Studies 1 and 2 we assessed a forward facing combination CRS design (intervention CRS) compared to a commercially available LATCH equipped model (control CRS) and in Study 3 we conducted a similar study using a convertible model of both the intervention and control CRS. Participants installed both CRS in a contemporary minivan and could choose which type of attachment to use for the control CRS (LATCH or seat belt); order of installation was counter-balanced. Evaluators systematically examined installations for accuracy and security.Results: Study 1: A greater proportion of participants in both the experienced and inexperienced groups was able to securely install the intervention CRS compared to the control CRS: (45% vs. 16%, p =.0001 for experienced) and (37% vs. 6%, p =.003 for inexperienced). No differences between the CRS were observed for accuracy of installation in either user group. Study 2: A greater proportion of participants were able to securely install the enhanced intervention CRS compared to the control CRS: (62% vs. 9%, p =.001). The intervention CRS demonstrated reduced installation accuracy: (30% vs. 61%, p =.001). Study 3: A greater proportion of participants was able to securely install the intervention CRS compared to the control CRS: 79% vs. 66% p =.03, but this effect was smaller than in the previous studies. Participants were less likely to achieve an accurate installation with the intervention CRS compared to the control CRS: 54% vs. 79%, p =.004. Common accuracy errors in each study included twisting or misrouting the seatbelt when installing the intervention CRS.Conclusions: Our results suggest that novel CRS designs that utilize mechanical advantage to facilitate attachment of the CRS to the vehicle result in a tighter installation compared to LATCH equipped models, but an increase in accuracy errors occurred.

Study on the accuracy of thoracolumbar pedicle screw installation assisted by O-arm navigation

Objective To evaluate the accuracy and reliability of O-arm-based thoracolumbar pedicle screw installation. Methods A retrospective review was conducted on 75 patients who had undergone thoracolumbar pedicle screw fixation assisted with O-arm navigation (navigation group, n=32) and C-arm fluoroscopy ( fluoroscopy group, n=43) from March to October 2014. All the patients were assessed with X-ray and CT images after operation. Accuracy of screw installation in both groups was compared. In navigation group, screw directions were measured on the sagittal and axial images of intra-operative navigation and post-operative CT scanning to evaluate the concordance. Results In fluoroscopy group, a total of 206 pedicle screws were placed with the one-time success rate of 93.2% and accuracy of 90.8% for screw placement, and one misplaced screw (grade Ⅲ) led to L3 nerve root symptom. In navigation group, a total of 226 pedicle screws were placed with the one-time success rate of 100% and accuracy of 96.9% for screw placement, and no screw was grade Ⅲ. Further, there were no significant differences in screw directions on the sagittal and axial images between intraoperative navigation and post-operative CT scanning (P>0.05). Conclusion O-arm navigation that provides high-resolution images and high precision improves the accuracy of thoracolumbar pedicle screw installation, and possesses good reliability. Key words: Spinal fractures; Surgery, computer-assisted; Thoracic vertebrae; Lumbar vertebrae; Pedicle screws

Analysis of Safety Characteristics and Optimization of Traverse Structural Elements for Installation of WSG-1000M Steam Generators Support

The high rate of construction and commissioning of new nuclear power plants involve the use of new and advanced methods of building construction and equipment installation. Serial reactor plant which includes the reactor, the main circulating pump and WSG-1000M steam generators is the basis of the Rostov nuclear power plant unit № 3. Steam generators supports are rather heavy equipment and their installation requires the use of the traverse with capacity of 40 tons. Its use greatly streamlines production assembly operations and allows to guarantee the required accuracy and quality of installation. The testing calculation of present traverse showed that it is designed and made with excessive margin of safety, and so it is uneconomical. Therefore recommendations of the traverse elements optimization allowing to reduce its metal consumption considerably were offered.

Study on Typical Diversion Structures and Fault of 220kV Cable-Conductor Bushings

According to a TOM bushing faults, three typical 220kV cable-conductor bushings (COT, TOM and BRDLW) widely used in the power grid are analyzed about diversion structure. Bushing diversion structure, diversion contact surface, current path and installation sensitivity are discussed in the paper. The study found that installation accuracy of TOM bushing has greater effect on contact resistance of diversion path than others. The improper installation of TOM bushing caused overheating defects and finally developed into this bushing fault.

Kinematics Simulation Based on ADAMS Belt Conveyor Rollers

Belt conveyor has the strong adapt ability and it uses widely in convey machinery. Roller is one of the key components in the belt conveyor; it plays an important role in the normal operation of belt conveyor. In order to study the influence factors of roller service life, this paper analyzed the movement of the roller and used Solid edge ST4 and ADAMS software to establish the virtual prototype model of roller and kinematics simulation of the model. This paper concludes the main factors affect the life are the sealing effect, poor alignment of the roller and the alignment of the bearing. Through the analysis of roller can reduce the design errors, improve the processing and installation accuracy mostly at the same time in the production process, it also can reduce the design and process time significantly and lower manufacturing cost and prolong the service life of roller.

Aerodynamic Analysis of the Static Port’s Step Height

To determine the static port’s installation accuracy requirement, the relationship between the step height and the static source error are studied by numerical simulation. It is found that the static pressure is higher than the pressure in far field when the step height is small, which is opposite when the step height is great. And the relative static source error is less than 0.18% when step height is within 0mm to 0.15mm. Besides, the maximum relative error caused by the uncertainty of the step height is found less than 0.06% if the installation accuracy of the static port is 0mm~0.1mm. By comparing the maximum static source error specified by airworthiness regulations, the static port’s installation accuracy requirement of 0.1mm is found to be appropriate.

The Application of BIM Technology to Improve the Installation Accuracy of Curtain

With the rapid development of the domestic curtain industry and higher pursue that people have about the architectural aesthetics, curtain wall has developed into a good direction of multiple component and complicated modelling little by little. Especially for the hyperboloidal modelling, it has increased engineered difficulty. For solving many problems in the engineering construction, we have introduced BIM technology to make the complicated problems simplify. This paper took an example of a certain center curtain case in Shanghai to introduce the application of complicated curtain execution stage with BIM technology.

Research on Vault Plate Installation Technology of LNG Storage Tank

Vault installation is one of the important parts of the LNG storage tank construction. Due to the large size, installation of high accuracy and the influence affected by complex factors such as wind load in hoisting process, the installation procedure is always controlled by artificial way which is low efficiency and a big risk. In this paper installation process is optimized. According to the structural characteristics of vault plate, this paper proposes a new kind of installation guide equipment and analyses the process of guiding, which can help vault plate realizing itself position. The equipment can greatly improve the installation accuracy and working efficiency, and also can reduce the risk of installation. The technology of vault plate installation of LNG storage tank has important practical value and significance.

Accuracy of free hand pedicle screw installation in the thoracic and lumbar spine by a young surgeon: an analysis of the first consecutive 306 screws using computed tomography.

Study DesignA retrospective cross-sectional study.PurposeThe purpose of this study is to evaluate the accuracy and safety of free-hand pedicle screw insertion performed by a young surgeon.Overview of LiteratureFew articles exist regarding the safety of the free-hand technique without inspection by an experienced spine surgeon.MethodsThe index surgeon has performed spinal surgery for 2 years by himself. He performed fluoroscopy-assisted pedicle screw installation for his first year. Since then, he has used the free-hand technique. We retrospectively reviewed the records of all consecutive patients undergoing pedicle screw installation using the free-hand technique without fluoroscopy in the thoracic or lumbar spine by the index surgeon. Incidence and extent of cortical breach by misplaced pedicle screw was determined by a review of postoperative computed tomography (CT) images.ResultsA total of 36 patients received 306 free-hand placed pedicle screws in the thoracic or lumbar spine. A total of 12 screws (3.9%) were identified as breaching the pedicle in 9 patients. Upper thoracic spine was the most frequent location of screw breach (10.8%). Lateral breach (2.3%) was more frequent than any other direction. Screw breach on the right side (9 patients) was more common than that on the left side (3 patients) (p<0.01).ConclusionsAn analysis by CT scan shows that young spine surgeons who have trained under the supervision of an experienced surgeon can safely place free-hand pedicle screws with an acceptable breach rate through repetitive confirmatory steps.

Research on Modeling and Simulation of the Trafficability of Vertical Screw Conveyors Intermediate Support Based on EDEM

Vertical screw conveyor is a kind of main equipments of bulk handing and delivery, and the intermediate support structure is one of the key parts of this equipment. It is necessary to make a research on it for improving the design and optimization to improve bulk delivery efficiency. Degree of freedom theory, analysis software of EDEM with discrete element and setting periodic boundary model are applied in this paper to simulate the vertical screw conveyors grain (rice) delivery process under different intermediate support structure. The results show that traditional intermediate support structure is three times statically indeterminate structure, while the degrees of freedom of new intermediate support is 1; The vertical screw transmission capacity of new type of vertical screw axis machine which uses intermediate spokes structure is slightly decreased, and the driving power required to drive screw axis increases slightly at the same time. The materials axial transport speed is not affected, but the requirement is greatly reduced for the manufacture and installation accuracy.

Strength and Displacement Analysis of a Nuclear Power Giant Lifting Grid and Steel Liner

Construction of nuclear power plant steel liner is an important component. The design and lifting is a highly complex technical systems engineering. For a nuclear power plant project in China, the displacement and strength of the grid and the steel liner have been analyzed in the lifting process by computer methods. The results show that the use of lifting truss design has good strength and stiffness, which can achieve the requirements. The steel liner in the lifting process itself is not overstressed and deformed. The lifting process can meet the engineering requirements of the installation accuracy.

Strength and Displacement Analysis of a Nuclear Power Giant Lifting Grid and Steel Liner

Construction of nuclear power plant steel liner is an important component. The design and lifting is a highly complex technical systems engineering. For a nuclear power plant project in China, the displacement and strength of the grid and the steel liner have been analyzed in the lifting process by computer methods. The results show that the use of lifting truss design has good strength and stiffness, which can achieve the requirements. The steel liner in the lifting process itself is not overstressed and deformed. The lifting process can meet the engineering requirements of the installation accuracy.

Two-Dimensional Laser Detection Front End Circuit and Algorithm

This paper describes the design of a two-dimensional photoelectric detector, in which silicon photovoltaic cells are used as photoelectric receiver, and laser signal is converted into electrical signals. The weak electrical signals can be amplified by the high power low noise with variable magnification amplifier controlled by single-chip microcontroller PIC. Then using the variable attenuator MAX521 complete selectable attenuation for the analog signal. The detector is able to adapt for high-precision detection of the laser light source in the case of changes in the strength of the near and far distances and light. The practicality and detection performance of the receiver can be ensured. This two-dimensional photoelectric detector is particularly applicable to the construction site where are special requirements for some installation accuracy, which can be a good solution to the problem of excessive error of the traditional installation process.

Study on Precision Measurement Technique for Cableway Tube of High Tower Column

In cableway tube of cable-stayed bridge construction, the precise location and loft cableway be installation accuracy an important part of construction. How fast, accurate the cableway tube precision positioning is the key to the construction of cable-stayed bridge tower column. In this paper, the actual project as an example, Creatively put forward based on the space linear equation and the method of measuring the elevation of Resemble-leveling method, Coordinates measured coordinates with the theoretical calculation coordinates difference. Through the cableway tube naturalization adjust, coordinate difference is zero, To determine the location of the installation of cableway tube. Thereby cableway tube positioning precision and speed of construction to improve.

Testing and Analysis for the Centralized Solar Hot Water System Comprehensive Benefit

In actual operation the centralized solar hot water system whether can more energy saving, influenced by the collector area design, system operation and control mode , installation accuracy and various factors so on. The analysis in this paper is mainly based on the measured data of the collector area key design parameters such as average daily water use, water temperature, the thermal collection efficiency, water tank and pipeline heat loss and other parameters, as well as the problem found in the test of the construction and operation control , put forward reasonable suggestions for energy saving potential, provide reference for the centralized solar hot water system design and operation in future.

Effect of Asynchronous Adjustments of Clamping Cylinders on Triangular Crack of Slab Castings Under Application of Soft Reduction

Soft reduction is known to be one of the best ways to improve the internal quality of slab castings such as center segregation, center porosity, centerline or triangular zone cracks, which is based on a proper adoption of the amount of reduction upon the given final solidification zone through roll gap adjustments. The synchronization of the clamping cylinders for roll gap adjustments should be very important to the application of soft reduction, including the synchronization of the clamping cylinders adjustments in the same and different segments. The synchronization of clamping cylinders adjustments is mainly affected by the adjustable accuracy of the four position-controlled clamping cylinders mounted in the upper frames of the segments according to a predetermined transformation relationship between the signals of displacement sensors and aimed roll gap, which, however, is also influenced by the installation accuracy, the precision of displacement sensors, the deformation of the segment frames and/or its bearing pedestals. Due to the actual asynchronous adjustments of the four clamping cylinders, the dynamic soft reduction operation is normally applied at non-ideal mechanical conditions. Here 7 possible situations of asynchronous adjustments of the local segments which may induce gap deviation have been presented. The roll gap deviation in the soft reduction region of a slab casting has been studied by a 3-D visco-elastic plastic FEM model, through which the additional inter-roll bulging, the related triangular cracks induced by one kind of the possible asynchronous adjustment situation and the effectiveness of soft reduction have been analyzed. A critical tolerance for the gap adjustments has been proposed for better contribution of soft reduction to the internal quality of slabs.

A Regulator Parameter Setting Simulation Research on Double Closed Loop Speed Control System

For the good performance of Double closed-loop DC speed control system, it is widely used . When the motor are selected, the parameters of the system can not be changed. Then,the system performance can only be improved by changing the parameters of the inner ring current regulator and outer ring speed regulator of the double-loop DC converter system. This paper studies mathematical modeling and system simulation of Direct Current Governor System on Matlab simulink platform. The simulation method, can adjust the system controller parameters flexibly, so as to achieve the ideal design results, and the design of the system are analyzed, the optimal "parameter range" is found, It can save the time of system development,and improve the standardization degree of system design.And the simulation results of the system can provide primary plannings and guidances for the actual system design,thereby lower the design cost of hardware largely, enhance the accuracy of hardware installation.

Influence of Vibration Inclination on Surface Quality and Tool Wear by Ultra-Precision Vibration-Assisted Cutting

Ultra-precision ultrasonic vibration-assisted cutting (UVC) with polycrystalline diamond (PCD) tool refers to the cutting with certain amplitude and high frequency tool vibration, which can definitely reduce the cutting forces and tool wear when compared with the conventional cutting. However, in the actual cutting process, the tool vibration direction is not strictly in accordance with the designed cutting direction based on the manufacturing dimension and installation accuracy error of the vibration device. It will result in an inclined cutting angled with the linear direction. The inclination angle leads to periodical grooves on the machined surface, therefore affecting the quality of machined surface. In addition, the inclined vibration cutting will also lead to an increase in cutting forces, thus exacerbating the PCD tool wear. This paper has analyzed the influence of inclined vibration on the roughness of machined surface. A finite element (FE) simulation model of inclined linear vibration cutting has also been set up to analyze the variations of cutting forces with different inclination angle, so as to explore the mechanism of tool wear. Moreover, ultra-precision ultrasonic vibration-assisted cutting (UVC) experiments with different inclination angle have been carried out. The machined surface and PCD tools have been investigated. Combining with the theoretical analysis, this work has concluded that inclined vibration will increase the roughness of machined surface as well as exacerbate the PCD tool wear. The effective techniques have been proposed to improve the surface quality and reduce the tool wear by reducing the inclination angle of vibration and with carbon atmosphere.

Mechanics Simulation and Analysis of the Main Palaestra of the World University Games during the Unloading Process

The steel roof of main palaestra of the World University Games is a long span space structure of single-layer fold face reticulated shells. The space positioning installation of members of this structure is very difficult, and the control accuracy is very high. In order to improving the installation accuracy of this space structure during the construction, a method named bulk-way assembly technology at high altitude with multi-points supporting had been adopted. After the closure of the steel roof structure the temporary supporting jigs began to be uploaded. During this process the supporting jigs quit work gradually and the main structure began to carry the load. Different uploading way will make different influence for the main structure and supporting jigs during the uploading process. These have to be considered in the structural design and construction stage. This article adopts construction mechanics and FEA method to analyze the uploading procedures according to the real construction process in order to finding the actual internal force and deformation and ensuring the security of the structure and supporting jigs. Lots of results have been obtained as guidelines in theory for the design and construction.