Data analytics to improve building performance: A critical review

Improving occupants' satisfaction with effective maintenance management of HVAC system in office buildings

Multi-criteria analysis for the selection of space heating systems in an industrial building

Longitudinal prediction of the operational energy use of buildings

Robust optimal design of building cooling systems considering cooling load uncertainty and equipment reliability

https://isiarticles.com/bundles/Article/pre/pdf/22375.pdf

Development of an optimal preventive maintenance model based on the reliability assessment for air-conditioning facilities in office buildings

Frequency lock-in-induced deadband phenomena are major problems of ring laser gyroscopes (RLGs), which deteriorate linear responses to changes in the applied rotation rate. In this work, the frequency lock-in phenomenon occurring in the RLG was successfully investigated by compensating for the Sagnac effect through frequency analysis using a newly defined error function. Integrative and generalized viewpoints from the analyzed results provide new possibilities for relevant performance improvements of optical gyroscopes, as well as a deeper understanding of locked states in principle aspects.

/pdf/sagnac-effect-compensations-and-locked-states-in-a-ring-2qq19bmk.pdf

Sagnac Effect Compensations and Locked States in a Ring Laser Gyroscope

The frequency lock-in phenomenon is the most important error factor that degrades the performance of a ring laser gyroscope by causing a nonlinear output to the rotational angular velocity input. To solve the problem of frequency lock-in, a mechanical dithering technique has been proposed and most successfully and widely applied to date. In addition, in the case of dithering with a sinusoidal signal of a single-frequency component, the theoretical background is well established. However, in actual applications, it is almost impossible to implement a perfect single sinusoidal signal, owing to various electrical and mechanical constraints. In general, although the occupied portion is smaller than the fundamental frequency component, the dithering signal inevitably includes harmonics. Therefore, it is essential to analyze the influence of the corresponding harmonic component to accurately predict the frequency lock-in characteristics of a ring laser gyroscope. In this study, it is assumed that the dithering signal has odd harmonics, and through numerical experiments, the frequency lock-in widths of the ring laser gyroscope according to the dithering amplitude change and the effectiveness of improving the related characteristics according to the application of random dithering are analyzed. The analysis confirmed that the resonance condition, including the higher harmonics of mechanical dithering, can be a major variable that determines the frequency lock-in characteristics of the ring laser gyroscope. To improve the relevant performance of the ring laser gyroscope, in-depth research from that point of view is necessary.

Effective Frequency Lock-In Changes of a Ring Laser Gyroscope Due to Harmonic Components of Dithering Signal

We develop a simple model to investigate the orientation-dependence of the drag force acting on a magnet falling inside a vertical conducting pipe. We approximate the magnet by a point magnet and the pipe by a two-dimensional cylindrical surface. Independent of the magnet's orientation, the drag force is proportional to its velocity: F→d=−kv→. We show that the coefficient k→ of the horizontally oriented magnet is about 2/3 of the coefficient k↑ for the vertically oriented magnet. If the magnetic moment makes an angle θ with the vertical direction, the drag coefficient k can be expressed as k=k↑ cos2θ+k→ sin2θ. When the magnet falls with a non-vertical orientation, a local charge distribution is induced in the pipe, which plays a role as important as that of the time-varying magnetic field due to the falling magnet in generating the eddy currents. The model's predictions are compared with experimental results.

Byung-Yoon Park

Papers

Development of an optimal preventive maintenance model based on the reliability assessment for air-conditioning facilities in office buildings

Sagnac Effect Compensations and Locked States in a Ring Laser Gyroscope

Effective Frequency Lock-In Changes of a Ring Laser Gyroscope Due to Harmonic Components of Dithering Signal

A magnet falling inside a conducting pipe: Dependence of the drag force on the magnet orientation