159 research outputs found
Research progress of MicroRNA in podocytes autophagy in diabetic nephropathy
Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes, and is a kind of abnormal microangiopathy of kidney structure, function or clinical indicators caused by diabetes. Podocyte injury has been considered as a major contributor to the progression of diabetic nephropathy(DN). microRNA can participate in podocytes injury through autophagy.In this paper, the mechanism of microRNA involved in DN podocytes autophagy was reviewed to provide reference for the treatment of DN in the future
Improving the operational bandwidth of a 1-3 piezoelectric composite transducer using Sierpinski Gasket fractal geometry
Wider operational bandwidth is an important requirement of an ultrasound transducer across many applications. It has been reported mathematically that by having elements with varying length scales in the piezoelectric transducer design, the device may possess a wider operational bandwidth or a higher sensitivity compared to a conventional device. In this paper, the potential for extending the operational bandwidth of a 1-3 piezoelectric composite transducer configured in a fractal geometry, known as the Sierpinski Gasket (SG), will be investigated using finite element analysis package PZFlex (Thornton Tomasetti). Two equivalent piezocomposite designs will be simulated: a conventional 1-3 piezocomposite structure and the novel SG fractal geometry arrangement. The transmit voltage response and open circuit voltage extracted from the simulations are used to illustrate the improved bandwidth predicted from the fractal composite design
Broadband piezocrystal transducer array for non-destructive evaluation imaging applications
A 32-element, 5MHz linear array, incorporating PMN-PT 1-3 piezo-polymer composite, has been designed using finite element (FE) modelling. The Elasto-Electric material properties of the PMN-PT samples were characterized and evaluated within the FE model to ensure accurate corroboration. The array configuration and performance were then investigated, including array microstructure, and steering and focusing ability. The matching and backing material selection, array sensitivity and bandwidth were assessed using pulse echo responses. Imaging performance was then undertaken, employing full matrix capture and total focusing method. For performance comparison, a reference array comprising of conventional PZT5H ceramic was also investigated, following the same design criteria. The piezocrystal device provides a bandwidth of 87% and a sensitivity-bandwidth product improvement of 160% when compared to the reference PZT5H based array
Broadband 1-3 piezoelectric composite transducer design using Sierpinski Gasket fractal geometry
Wider operational bandwidth is an important requirement of an ultrasound transducer across many applications. In nature, it can be observed that several hearing organs possess a broad operating bandwidth by having a varying length scales structure. Moreover, conventional 1-3 piezoelectric composite transducers have been widely recognized for their wider bandwidth over their piezoelectric ceramic counterparts. In this paper, a novel 1-3 piezoelectric composite design using a fractal geometry, known as the Sierpinski Gasket (SG), is proposed in order to explore the potential of further extending the operational bandwidth and sensitivity of the transducer. Two equivalent 1-3 piezocomposite designs are compared to this end, one with a conventional periodic parallelepiped shaped pillar structure and one with the SG fractal geometry, both theoretically, using a finite element (FE) analysis package, and experimentally. The transmit voltage response and open circuit voltage response are used to illustrate bandwidth improvement from the fractal composite design. Following the simulation results, a 580 kHz single element transducer, utilizing the proposed SG fractal microstructure, is fabricated using a pillar placement methodology. The performance of the prototyped device is characterized and compared with a conventional 1-3 composite design, as well as with a commercial ultrasound transducer. In the one-way transmission mode, a bandwidth improvement of 27.2 % and sensitivity enhancement of 3.8 dB can be found with the SG fractal design compared to an equivalent conventional composite design and up 105.1 % bandwidth improvement when compared to the commercial transducer. In the one-way reception mode, the bandwidth improvement for the SG fractal design is 2.5 % and 32.9 % when compared to the conventional and commercial transducers, respectively
XRL-Bench: A Benchmark for Evaluating and Comparing Explainable Reinforcement Learning Techniques
Reinforcement Learning (RL) has demonstrated substantial potential across
diverse fields, yet understanding its decision-making process, especially in
real-world scenarios where rationality and safety are paramount, is an ongoing
challenge. This paper delves in to Explainable RL (XRL), a subfield of
Explainable AI (XAI) aimed at unravelling the complexities of RL models. Our
focus rests on state-explaining techniques, a crucial subset within XRL
methods, as they reveal the underlying factors influencing an agent's actions
at any given time. Despite their significant role, the lack of a unified
evaluation framework hinders assessment of their accuracy and effectiveness. To
address this, we introduce XRL-Bench, a unified standardized benchmark tailored
for the evaluation and comparison of XRL methods, encompassing three main
modules: standard RL environments, explainers based on state importance, and
standard evaluators. XRL-Bench supports both tabular and image data for state
explanation. We also propose TabularSHAP, an innovative and competitive XRL
method. We demonstrate the practical utility of TabularSHAP in real-world
online gaming services and offer an open-source benchmark platform for the
straightforward implementation and evaluation of XRL methods. Our contributions
facilitate the continued progression of XRL technology.Comment: 10 pages, 5 figure
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