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Important reserves of oil and gas, which are left to be discovered and produced, are mainly concentrated in challenging locations and under severe conditions such as high pressure (HP)/high temperature (HT). The presence of aggressive environments including H₂S, CO₂ and chlorides plus HP/HT causes a series of corrosion problems, which cost the oil industry billions of dollars a year. Thus, there is an increasing challenge for tubes (i.e. oil country tubular goods, for short, OCTG) used in producing oil and gas. The purpose of this study is to summarize different kinds of corrosion problems and their mitigation, to more efficiently protect OCTG from corrosion.

To effectively select proper mitigation methods, the mechanism of corrosion must be understood, which can be classified into four categories: sweet corrosion, sour corrosion, galvanic corrosion and microbiologically induced corrosion. Also, the effects of environmental and material factors on the corrosion rate are presented. Subsequently, current technology of mitigating these corrosion problems has been discussed, including the development of materials, application of chemical inhibitors and application of protective layers.

It is stressed that limits exist for each individual mitigation method; therefore, a careful balance between economic life of OCTG and safety in operation is required.

The main purpose of this essay is to give a brief review and detailed introduction and analysis about those technologies.

This paper aims to concentrate on recent innovations in flexible wearable sensor technology tailored for monitoring vital signals within the contexts of wearable sensors and systems developed specifically for monitoring health and fitness metrics.

In recent decades, wearable sensors for monitoring vital signals in sports and health have advanced greatly. Vital signals include electrocardiogram, electroencephalogram, electromyography, inertial data, body motions, cardiac rate and bodily fluids like blood and sweating, making them a good choice for sensing devices.

This report reviewed reputable journal articles on wearable sensors for vital signal monitoring, focusing on multimode and integrated multi-dimensional capabilities like structure, accuracy and nature of the devices, which may offer a more versatile and comprehensive solution.

The paper provides essential information on the present obstacles and challenges in this domain and provide a glimpse into the future directions of wearable sensors for the detection of these crucial signals. Importantly, it is evident that the integration of modern fabricating techniques, stretchable electronic devices, the Internet of Things and the application of artificial intelligence algorithms has significantly improved the capacity to efficiently monitor and leverage these signals for human health monitoring, including disease prediction.

This research aims to combine the throttling structure with the elastic element to enhance the load performance of aerostatic radial bearing.

In this research, a fluid–solid coupling model of the elastic throttling structure is established while considering the interaction between the elastic element and the flow field. The effects of elastic element structural parameters on the stiffness and load capacity of aerostatic radial bearing are then researched. Finally, the effect of elastic element modulus on air film load performance and elastic element deformation is analyzed.

The results indicate that the aerostatic radial bearing with elastic element can significantly improve the load capacity and stiffness when compared to the common aerostatic bearing. By choosing the proper combination of parameters, the load performance can be improved by at least 16%.

The throttling structure of aerostatic bearing is optimized in this work, which significantly enhances the load performance of the aerostatic bearing.

To identify the dynamic feature of the aerostatic slider caused by gas film, an evaluation system by a piezoelectric acceleration sensor is presented in time and frequency domain.

The dynamic pressure fluctuation is evaluated by the wavelet transform, cross correlation analysis and power spectral density (PSD). Wavelet transform is used to process the measured result of the aerostatic slider and the signal is decomposed into high-frequency and low-frequency signal. Correlation analysis method is used to evaluate the impact of the initial gas gap on the fluctuation in time domain.

According to the PSD analysis of the processed signal in the frequency domain, the natural frequency of the aerostatic slider is identified from the measured signal in frequency domain; this method provides a basis for the identification of guideway errors.

The method can also be applied to the error identification of other components of the machine tool.

Wavelet transform is used to process the measured result of the aerostatic slider by acceleration sensor, and the signal is decomposed into high-frequency and low-frequency signal. Correlation analysis method is used to evaluate the impact of the initial gas gap on the fluctuation in time domain. According to the PSD analysis of the processed signal in the frequency domain, the natural frequency of the aerostatic slider is identified from the measured signal in frequency domain; this method provides a basis for the identification of slider errors.

This paper aims to better understand the dynamic characteristics of an aerostatic slider caused by a gas film, and the impact of a gas film slip on the load capacity, stiffness and dynamic stiffness of the guideway is studied.

In theory, the Navier velocity slip model is introduced for fluid continuous flow equation to calculate the flow state in the micro-state; in experimental techniques, the stiffness experiment of the guideway by digital inductance meter is performed under different loadings, which are used to inspect the simulation results.

The maximum value of bearing stiffness in the condition of considering that the gas slip is larger than that of not considering the gas slip, and the gas film clearance of maximum bearing stiffness in the condition of considering the gas slip is less than that of not considering the gas slip. This is verified by the measurement of the stiffness of the guideway.

This paper mostly studies the influence of the gas slip effects on the performance of the aerostatic guideway, which will make a certain contribution to the guideway stability and the machining precision of the machine tool.