Optimising The Reference Point Within A Journal Bearing Using Laser Alignment

This paper observes different alignment conditions in a journal-bearing-supported machine (i.e. propeller bearings within the stern tube of a marine vessel). A test rig is built so that the driven machine has fixed supports, roller bearings in an electrical motor. An alignment tolerance is met at the coupling of the journal, which is positioned within three journal bearings. This research can be applied to any industry with machines of the same characteristic. The journal bearings are designed to simulate the large tolerance seen in a vessel’s stern tube only for lubrication control oil is used for the bush bearings. Various sensors are placed on the test rig to record data for later machine analysis. Using proximity probes and accelerometers the vibration of the journals and ball bearings can be visualised using orbital plotting and Fast Fourier Transform (FFT) through both LabVIEW and MATLAB respectively. Four alignment procedures are applied to the coupling using a laser unit. The first two will be so that the offset and angular misalignment is produced in the FFT spectrums as per ISO10816 Mechanical vibration so that a reference point is formed for the test rig. The other two alignment procedures represent current industry practice. These procedures are then compared to see which is the preferred reference point that will optimise the reliability value of a whole system. Finding the procedure with minimal vibration will increase the design life of housing structures for such machines, which will increase the overall profit of the shipping industry. Our developments and procedures will be further utilized in practical classes to improve maritime engineering education.

Tumbling and anomalous alignment of optically levitated anisotropic microparticles in chiral hollow-core photonic crystal fiber

The complex tumbling motion of spinning nonspherical objects is a topic of enduring interest, both in popular culture and in advanced scientific research. Here, we report all-optical control of the spin, precession, and nutation of vaterite microparticles levitated by counterpropagating circularly polarized laser beams guided in chiral hollow-core fiber. The circularly polarized light causes the anisotropic particles to spin about the fiber axis, while, regulated by minimization of free energy, dipole forces tend to align the extraordinary optical axis of positive uniaxial particles into the plane of rotating electric field. The end result is that, accompanied by oscillatory nutation, the optical axis reaches a stable tilt angle with respect to the plane of the electric field. The results reveal new possibilities for manipulating optical alignment through rotational degrees of freedom, with applications in the control of micromotors and microgyroscopes, laser alignment of polyatomic molecules, and study of rotational cell mechanics.

Development and Longitudinal Analysis of Plan-Based Streamlined Quality Assurance on Multiple Positioning Guidance Systems With Single Phantom Setup

PurposeThis study was to propose and validate an efficient and streamlined quality assurance (QA) method with a single phantom setup to check performances of patient positioning guidance systems including six-degree-of-freedom (6DoF) couch, X-ray modalities (kV–kV, MV–MV and CBCT), optical surface imaging system (AlignRT), lasers and optical distance indicator (ODI).Methods and MaterialsThe QA method was based on a pseudo-patient treatment plan using the AlignRT cube phantom. The cube was first randomly set up on the couch, and the initial position offsets were acquired by AlignRT and CBCT. The cube was restored to its reference position by 6DoF couch shift, during which the couch motion accuracy and tracking performances of AlignRT and CBCT were derived. After that, the residual offsets were acquired by kV–kV, MV–MV and AlignRT to derive the isocenter discrepancies. Finally, the laser alignment and ODI values were visually inspected. The QA procedure had been internally approved as a standard weekly QA test, and the results over 50 weeks were longitudinally analyzed for clinical validation.ResultsThe 6DoF couch motion errors as well as the tracking errors of AlignRT were sub-millimeter and sub-degree, and no deviation over 1 mm or 1 deg was identified. The ROI mode of isocenter (ISO) in AlignRT exhibited more consistent results than the centroid (CEN). While the isocenter discrepancy between CBCT and kV–kV was negligible, the maximal discrepancies between CBCT and MV–MV were 0.4 mm in LNG and 0.3 deg in PITCH. The isocenter discrepancies between CBCT and AlignRT were <0.5 mm in translation and <0.3 deg in rotation. For AlignRT, the isocenter discrepancies between the DICOM and SGRT references were about 0.6 mm in VRT, 0.5 mm in LNG and 0.2 deg in PITCH. As the therapists became familiar with the workflow, the average time to complete the whole procedure was around 23 min.ConclusionsThe streamlined QA exhibits desirable practicality as an efficient multipurpose performance check on positioning guidance systems. The stability, tracking performance and isocenter congruence of the positioning guidance systems have been fully validated for all clinical image guidance RT application, even SRS/SBRT, which requires the strictest tolerance.

Alignment Methods in Rotating Equipment

This research provides an analysis about the need to implement innovative alignment techniques and to diversify the methods to carry it out, if there is outdated equipment, misalignment becomes more recurrent and this causes the equipment to present failures as high vibration, high temperature, product leaks, excessive energy consumption and wear of some equipment components. In turn, this text exposes the methodologies of alignment of axes by straight edge, dial indicator, and by laser alignment, and makes a comparison of the advantages and disadvantages between these three methods to conclude which of them brings greater benefits to the industry today.

PENGARUH PEMUAIAN PANAS TERHADAP KELURUSAN POROS TURBIN UAP

Sebagian besar penyebab kegagalan pada mesin-mesin rotasi termasuk turbin uap adalah poros yang berputar dalam kondisi misalignment. Pada turbin uap, panas yang merambat pada casing dapat merubah dimensi turbin uap karena adanya pemuaian (thermal growth) sehingga mempengaruhi kelurusan poros saat berputar. Nilai thermal growth ini perlu diketahui sebagai salah satu spesifikasi dalam penyetelan poros sebelum turbin beroperasi. Dalam studi ini, Â thermal growth pada turbin uap 3 MW diinvestigasi dengan mengukur kelurusan poros dalam kondisi panas setelah berhenti berputar dan dingin menggunakan metode laser alignment. Hasil pengukuran menunjukkan bahwa thermal growth memberikan pengaruh terhadap kelurusan poros karena adanya selisih nilai kelurusan poros saat kondisi panas dan dingin yaitu 1.0 thous (gap) dan 2.8 thous (offset) pada bidang vertikal kemudian -1.0 thous (gap) dan -2.7 thous (offset) pada bidang horisontal.Kata kunci : Turbin uap, Thermal growth, Kelurusan porosMost of the causes of rotating machines failure including steam turbine is shaft misalignment. In the steam turbine, heat that travels to the casing can change steam turbine dimension due to thermal growth which affects the shaft alignment. Thermal growth values needs to be known as one of the specifications in shaft alignment setup. In this study, thermal growth on 3 MW steam turbine was investigated by measuring the shaft alignment in hot after shut down and cold condition using laser alignment method. Results show that thermal growth has an influence on shaft alignment due to difference of alignment values when hot and cold conditions, namely 1.0 thous (gap) and 2.8 thous (offset.) in vertical plane then -1.0 thous (gap) and -2.7 thous (offset.) in horizontal plane.Key Words : Steam Turbine, Thermal growth, Shaft alignmentÂ

Two tailorable two-arms-cross patterns with equal intensity generated by a composite square zone plate

A composite square zone plate (CSZP) is proposed to generate two two-arms-cross patterns with equal intensity and arbitrarily designed axial positions. Moreover, the CSZP with the spiral phase has two square optical vortices located at the arbitrary positions. In addition, we find that the same topological charge of twin square optical vortices for the CSZP follows a modulo-4 transmutation rule. The construction method of proposed zone plates is illustrated in detail. We prove numerically and experimentally that the CSZP and spiral-phase CSZP produce two tailorable two-arms-cross patterns with equal intensity and square optical vortices, respectively. The proposed zone plate can be used to generate hollow beams and have potential applications in infrared antennas and laser alignment systems.