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A rotational sponge (RS) reactor was proposed as an alternative sewage treatment process. Prior to the application of an RS reactor for sewage treatment, this study evaluated reactor performance with regard to organic removal, nitrification, and nitrogen removal and sought to optimize the rotational speed and hydraulic retention time (HRT) of the system. RS reactor obtained highest COD removal, nitrification, and nitrogen removal efficiencies of 91%, 97%, and 65%, respectively. For the optimization, response surface methodology (RSM) was employed and optimum conditions of rotational speed and HRT were 18 rounds per hour and 4.8 h, respectively. COD removal, nitrification, and nitrogen removal efficiencies at the optimum conditions were 85%, 85%, and 65%, respectively. Corresponding removal rates at optimum conditions were 1.6 kg-COD m −3 d −1 , 0.3 kg-NH 4 + -N m −3 d −1 , and 0.12 kg-N m −3 d −1 . Microbial community analysis revealed an abundance of nitrifying and denitrifying bacteria in the reactor, which contributed to nitrification and nitrogen removal. [ABSTRACT FROM AUTHOR]

The activity of wheel-throwing a ceramic vessel is governed by a number of physical forces. These are the rotational kinetic energy (expressed in terms of angular velocity and the moment of inertia) and manual pressures. Given the importance of the potter's wheel worldwide, and the frequently postulated socio-cultural meaning of wheel-throwing in particular, foundational research on the physics behind wheel-throwing has been under-represented, and there is a lack of understanding of the relationship between speed of wheel rotation, lifting speed and the orientation of clay pores or inclusions. The speed of rotation is highly relevant as different wheels can achieve different speeds. Thus, knowing the speed during manufacture may allow scholars to reconstruct the original device, manufacturing technique, and perhaps even the potter's level of skill. Two contrasting views can be found in the literature: a) there is a direct positive relationship between these variables, and that the angle of the inclusions/voids can therefore tell us about the wheel's speed at the time of making the pot and hence the device used; b) because pots are never thrown in one single motion, the angle of inclusions/voids is an averaging of all actions executed by the potter, and thus cannot provide meaningful inferences about speeds or device. Experiments with professional potters were devised to explore the relationship between these variables. They show that the interaction between the various physical forces, clay and potter is complex, leading to a large variance even within the work of a single potter, with finger pressure recognized as a major influencing variable. It is clear that angles of inclusions or voids cannot be used to project backwards to the wheel speed, lifting speed, skill level or device used. • Diagonal angle alignment of inclusions or voids identifies a vessel as wheel-thrown • Inclusion/void orientation does not allow retrospective deductions on wheel speed, lifting speed, the device used or a potter's skill • Inclusion or void orientation varies intra- and inter-potter • Finger pressure is most likely responsible for the steep inclusion or void orientation characteristic of wheel-throwing [ABSTRACT FROM AUTHOR]

Phase demodulation is arguably the most used technique for the estimation of the instantaneous angular speed from vibration signals measured on rotating machinery. Although phase demodulation offers a straightforward approach to determine accurately the rotation speed of a particular shaft in a rotating machine, it does have strict limitations that can hinder the estimation accuracy and its overall reliability. In general, phase demodulation relies on the presence of a single harmonic with a high signal-to-noise ratio for the full duration of the measured vibration signal. Such a precondition hinders its applicability for a generic speed estimation approach for rotating machinery. There are copious real-world scenarios where this requirement is not met, especially given the increasing complexity and dynamic operating range of rotating machines nowadays. In such complex rotating systems, the deterministic signals are not necessarily all harmonically related to a fundamental harmonic. The presence of crossing harmonic orders from non-synchronous rotating components or of lightly damped structural resonances can significantly skew the instantaneous phase demodulation. This paper proposes a novel approach towards phase demodulation by both incorporating multiple harmonics in the demodulation process and also giving the individual harmonic phases time-dependent weighting. This combination of incorporating multiple harmonics and weighting them allows for fully exploiting the information contained within the vibration signal while also promising to be more robust to changing operating regimes. The proposed multi-harmonic demodulation method is investigated thoroughly by assessing its performance on simulated data, on two benchmark experimental data sets, and on a large wind turbine vibration data set consisting of thousands of vibration measurements. • Multi-harmonic extension of standard single harmonic phase demodulation. • Maximum likelihood weighting of harmonics improves accuracy and ease-of-use. • Validation on simulated and experimental data sets. • Good performance on complex non-stationary machine vibrations. [ABSTRACT FROM AUTHOR]

• The amplitude of out-put signal reflects the torque and frequency reflects the rotational speed. • It solves the problem of power supply and signal output of sensitive elements on the shaft. • This sensing method cleverly uses the non-contact principle of capacitance. Torque and rotational speed are important parameters to characterize the power of rotating parts for mechanical systems, so a rotational shaft's torque and rotational speed sensing method and real-time signal processing are key technologies for mechanized equipment, such as vehicles, ships, etc. Hence an advanced torque and speed sensing technology and a data processing technology are very important for improving the performance of mechanical equipment. However, the power transmission device's rotational shaft has a compact structure and narrow space, so it is difficult to install a signal transmission and power supply device of a sensor on the rotational shaft. To solve these difficult problems, this paper proposes a rotational shaft torque and rotational speed measurement method coupling resistance and capacitance. This method uses two resistance strain gauges and a capacitive grating, and the capacitive grating transmits signals in a non-contact coupling manner. The sensor on the rotational shaft needs no power supply and the signals are transmitted to a measurement circuit from a stationary sleeve, so this method essentially solves the difficult problems in signal transmission and power supply. Simulation and measurement experiments show that the resistance strain gauges obtain information and the capacitive grating sensor transfers information. The method coupling resistance and capacitance for realizing information sensing is feasible, which is suitable for measuring the torque and rotational speed of the rotational shaft of mechanical equipment in spite of the compact structure and narrow space. [ABSTRACT FROM AUTHOR]

The paper investigates the in-plane vibration property of static and rotating tires with the proposed tire model. The tire model is based on the linear ring model, and a mathematical approach is proposed to handle the tire contact problem. With this improvement, the tire model allows for directly calculating the eigenmodes of a loaded tire by solving its eigenvalue problem. A group of simulations is carried out using this improved ring model. For a static (not rotating) tire, the eigenfrequency and corresponding mode shape are investigated under both unloaded and loaded conditions. For a rotating tire, the effect of rotational speed on the eigenfrequencies of unloaded and loaded tires are modeled, and the results are observed using co-rotating and non-rotating reference frames. The main original contribution of this work is an evaluation of the quantitative relationship between unloaded and loaded conditions using modal assurance criterion (MAC) or improved modal assurance criterion (IMAC) analyses on both static and rotating tires. For a static tire, the eigenmodes can be classified into rigid ring modes and flexible ring modes, according to their mode shape and MAC evaluation results. For a rotating tire, the eigenfrequency and mode shape could vary with increasing rotational speed and behave differently in non-rotating and co-rotating reference frames. In a non-rotating frame, the IMAC value percentages for a loaded tire vary with increasing rotational speed, especially in the frequency veering ranges. In a co-rotating frame, the IMAC value variations for loaded modes are weaker than those seen in a non-rotating frame. [ABSTRACT FROM AUTHOR]