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Endoscopic photoacoustic tomography (EPAT) is an interventional application of photoacoustic tomography (PAT) to visualize anatomical features and functional components of biological cavity structures such as nasal cavity, digestive tract or coronary arterial vessels. One of the main challenges in clinical applicability of EPAT is the incomplete acoustic measurements due to the limited detectors or the limited-view acoustic detection enclosed in the cavity. In this case, conventional image reconstruction methodologies suffer from significantly degraded image quality. This work introduces a compressed-sensing (CS)-based method to reconstruct a high-quality image that represents the initial pressure distribution on a luminal cross-section from incomplete discrete acoustic measurements. The method constructs and trains a complete dictionary for the sparse representation of the photoacoustically-induced acoustic measurements. The sparse representation of the complete acoustic signals is then optimally obtained based on the sparse measurements and a sensing matrix. The complete acoustic signals are recovered from the sparse representation by inverse sparse transformation. The image of the initial pressure distribution is finally reconstructed from the recovered complete signals by using the time reversal (TR) algorithm. It was shown with numerical experiments that high-quality images with reduced under-sampling artifacts can be reconstructed from sparse measurements. The comparison results suggest that the proposed method outperforms the standard TR reconstruction by 40% in terms of the structural similarity of the reconstructed images.

This paper briefly introduces the current status of drilling fluid waste and its impact on the surrounding environment. Based on the analysis of the current situation of drilling fluid waste in the oilfield, the evaluation criteria of drilling waste are clarified, and a new technology for the harmless treatment of water-based drilling fluid waste is proposed, which includes a new type of environmental protection agent and armored modularization. Design, automation and intelligent control, etc., hope to provide reference for the later drilling fluid waste treatment.

Drilling fluid waste is the multiphase stable suspension composed of clay, drilling cuttings, weighting materials, chemical additives, inorganic salts and oil, containing a variety of substances harmful to the environment, such as oil, chemical additives, heavy metals and macromolecule organic compound. The effects of drilling fluid waste on the environment is mainly reflected in following aspects: pollution of surface water and groundwater resources; hardening of soil is harmful to plant growth or even unable to grow, resulting in the soil can not be replanted; various heavy metals and chemical additives affect the growth of animals and plants, and even are enriched in animals and plants, thus endangering human health. It is unfavourable to the implementation of the strategic objective of sustainable development of the environment and economy, so the drilling fluid should be treated innocuously after drilling.