Papers by Keyword: Magnification

Abstract: The aim of this study is to highlight the morphology of the second maxillary molars root canals and to draw a comparison between the data obtained with and without magnifying means. The study covered a total of 31 extracted human second maxillary molars. After being examined by a thorough physical exam and an X-ray examination, teeth were trepanned in the place of election. Thereby the access cavity was performed using: a) for the stage of pulp chamber ceiling penetration, a globular diamond bur for the turbine, b) for the stage of broadening access cavity, a cylindrical bur inactive in the head for the opposite-angle piece and c ) a Batt bur for the flaring and finishing stage.Afterwards, the sighting of the main root canals was performed using the endodontic probe or Miller file. Examination and sighting of the additional canals was made under magnification using the dental microscope. The molars with three canals had the highest prevalence of endodontic morphology of two upper molars (90.32%). But there were special cases with two channels morphology (6.45%) and four channels morphology (3.22%). After examining the endodontic space under the microscope, there have been identified and secondary canals, approximately 32.25% of molars examined presenting one or more secondary canals. The anatomy of the most frequent upper second molar was three roots with three root canals; the most common variation in morphology is the presence of an mesiobuccal additional canal (MB2). However, we can encounter an unusual number of canals. The importance of magnification, of the dental microscope in our study cannot be ignored because using only the latter we could highlight the real endodontic morphology of the two upper molars extracted examined, finding additional canals in 32.25% of the molars undergoing examination.

Abstract: For mobile devices with existing servo repair problems encountered. Eager to achieve functional replacement of the existing servo device through the use of new technologies. Mechatronic transformation active servo control device artillery, with a small technical risk, less funding, renovation cycle is short, etc., can form new parts supply capacity, which can increase the active duty army air defense artillery maintenance support capability, to extend the service life of the same model.

Abstract: A strain based dynamometer used for the prediction and measurement of three-component cutting forces for milling operations has been designed on the basis of the principle of additional elastic element theory. Meanwhile, four Wheatstone bridges, considerable amplifier and data acquisition software based on LabVIEW are also used to compose a whole system acquiring the cutting force signals. In order to obtain higher natural frequency and magnification, this paper focuses on the calculation and optimization of the dimensions of the special structure, and finally its first natural frequency can be stabilized at more than 14kHz, which are high enough to precisely measure the cutting forces, and the magnification can also achieve up to 15. The dynamic characteristics of the dynamometer are studied theoretically and experimentally, the results show that the developed dynamometer is able to measure the dynamic force component in high-speed cutting.

Abstract: A new method to correct a distorted image is proposed in this paper, which is based on the relationship between image magnification and distortion coefficient. First, the image magnification is solved. Then, the image distorted coefficient can be obtained with simple linear operation. Ultimately, experiments are carried out, and the correction results obtained by the collinear points-based method are compared with the method proposed in this paper. The results show that both provide good correction effects. At the same time, the accuracy of the new proposed method is higher. The proposed method takes the advantages of simple algorithm, few known conditions and fast computing speed. The new method has great significance in engineering metrology and complex condition.

Abstract: Flexure-hinge mechanisms are commonly used in the design of translational micro/nanopositioning stages. They can offer a drive system with negligible friction and no need for lubrication. Usually, a large motion range requires the use of a very long actuator which could interfere with a tight workplace. A lever which amplifies the input motion of a short actuator is an effective technique to solve the problem. This paper presents the methodology for the design of a lever-type magnified flexure mechanism used for the ultra precision fast tool servo (FTS) system. A lever type hinge mechanism is designed and utilized to guide the tool holder and to preload the PZT actuator. A low capacitance PZT actuator is adopted to match the given amplifier to achieve optimum performance of device displacement. A high resolution capacitive sensor is utilized to measure the natural displacement of the tool holder. An amplifier with a multiplying factor of 12 is utilized to magnify the drive signal for the expansion and retraction of the PZT actuator. Meanwhile, the motion range of the FTS system can reach up to 98.12 μm with a primary resonant frequency of about 460 Hz, and the amplification of the lever flexure mechanism is approximately 5 as calculated from the experiment.

Abstract: A new method to correct a distorted image is proposed, which is based on the relationship between image magnification and distortion coefficient. Firstly, the image magnification is solved. Then, the image distorted coefficient can be obtained by simple linear operation. Ultimately, experiments are carried out, where the correction results obtained by the collinear points-based method are compared with the method proposed in this paper. The results show both provide good correction effects, but, the accuracy of the new proposed method is higher and the proposed method takes the advantages of simple algorithm, few known conditions and fast computing speed. The new method has great significance in engineering metrology and complex condition.

Abstract: The high precise measurement for magnification of optical system of microscope has been demonstrated by using special barcode design and precise barcode image processing technologies. The magnification measurement with 50ppm accuracy is obtained. According to the measurement error estimation, the accuracy for system magnification device is about 0.06%. Barcode position is possible to reach 0.5μm for low magnification and 0.1μm for high magnification.

Abstract: Optical profiler is a typical modern device for precision form error measurement. In our use of the equipment, we found that the surface form profile after stitching is ambiguous if the lens magnification is changed. The error in terms of PV value can be up to 3200% when the lens magnification changes from 2.5 times to 30 times. This has been confirmed by the equipment supplier. It is worthwhile to offer a comprehensive study as many users may use the instrument of the kind straightforward without detailed investigation of the performance. We found that, among the 6 key parameters studied, 3 independent parameters are more important. For the 3 independent parameters, we recommend to set the magnification A=2.5 times, the resolution r=0.5, and the overlap p=20%. With the recommended settings, the measurement error can be less than 0.5%. Backscan and length for scanning in the vertical direction, and cut off frequency for delivering form profile are less critical compared with the three independent parameters.