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Background: Pneumatosis cystoides intestinalis is a rare intestinal disease characterized by single or multiple air cysts in the submucosa or subserosa of the intestinal wall. It is often accompanied by other gastrointestinal diseases. The clinical manifestations were nonspecific, and the diagnosis mainly depended on colonoscopy, imaging, and other auxiliary examinations. Case presentation: The reason for pneumatosis cystoides intestinalis's occurrence remains unclear. Enteral nutrition deficiency, especially the use of glucosidase inhibitors, may be involved in the pathogenesis of pneumatosis cystoides intestinalis in this patient. Here, we report a rare case of pneumatosis cystoides intestinalis in an elderly man who had been taking acarbose for diabetes for a long time. Colonoscopy of the patient was normal before taking acarbose. Conclusion: In patients with diabetes who are treated with glucosidase inhibitors for gastrointestinal symptoms, the possibility of pneumatosis cystoides intestinalis should be considered, and a thorough gastrointestinal examination should be performed in such patients. [ABSTRACT FROM AUTHOR]

Due to the complex characteristics of chaotic system, such as initial value sensitivity, periodicity and pseudo-randomness, chaotic sequences generated by chaotic system is very suitable for image data encryption after appropriate processing. This paper focuses on chaotic image encryption based on the improved Joseph algorithm, and proposes a hyperchaotic image encryption system based on N + 2 ring Joseph algorithm and reversible cellular automata. The initial value of the chaotic system is generated by the SHA-512 hash value of the original image, which makes the proposed encryption algorithm highly sensitive to the original image. In addition, the proposed N + 2 ring Joseph algorithm is formed by N chaotic sequences rolling forward like gears when scrambling each pixel position of the image. It greatly hides the pixel information of the original text, and increases the scrambling effect and the difficulty of being cracked. Furthermore, in the diffusion stage, we add the reversible cellular automata technology. On the basis of image shuffling, each pixel is further associated with other pixels, so that small changes of in pixel values can produce an avalanche effect. Finally, we conducted simulation experiments and safety analysis. The results illustrate that the encryption algorithm proposed in this paper has good encryption performance, and can effectively resist statistical attacks, differential attacks, known plaintext attacks, ciphertext only attacks, select plaintext attacks and select ciphertext attacks. In conclusion, it is a practical and secure image encryption algorithm. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to construct a multiwing chaotic system that has hidden attractors with multiple stable equilibrium points. Because the multiwing hidden attractors chaotic systems are safer and have more dynamic behaviors, it is necessary to construct such a system to meet the needs of developing engineering. Design/methodology/approach: By introducing a multilevel pulse function into a three-dimensional chaotic system with two stable node–foci equilibrium points, a hidden multiwing attractor with multiple stable equilibrium points can be generated. The switching behavior of a hidden four-wing attractor is studied by phase portraits and time series. The dynamical properties of the multiwing attractor are analyzed via the Poincaré map, Lyapunov exponent spectrum and bifurcation diagram. Furthermore, the hardware experiment of the proposed four-wing hidden attractors was carried out. Findings: Not only unstable equilibrium points can produce multiwing attractors but stable node–foci equilibrium points can also produce multiwing attractors. And this system can obtain 2N + 2-wing attractors as the stage pulse of the multilevel pulse function is N. Moreover, the hardware experiment matches the simulation results well. Originality/value: This paper constructs a new multiwing chaotic system by enlarging the number of stable node–foci equilibrium points. In addition, it is a nonautonomous system that is more suitable for practical projects. And the hardware experiment is also given in this article which has not been seen before. So, this paper promotes the development of hidden multiwing chaotic attractors in nonautonomous systems and makes sense for applications. [ABSTRACT FROM AUTHOR]

Center cone locating at the rear portion of turbine is the key component of the integrated afterburner. Numerical studies were carried out to investigate full-coverage film cooling on center cone at engine-realistic conditions, and the effects of thermodynamic and geometric parameters on cooling effectiveness and aerodynamic loss were discussed in detail. The numerical model was validated by the infrared measured experiments. Two recirculation vortices were generated on the cone surface, and cause the reverse ejection of coolant. These two recirculation vortices were promoted by increasing blowing ratio, and mixed with each other as the blowing ratio reaches 3.0. Along the streamwise direction, cooling effectiveness decreases and reaches the minimum value at the tip of cone, which is very different from the flat-plate film cooling. Cooling effectiveness increases with the increases of blowing ratio, hole diameter and density ratio, but decreases with the increases of hole pitch and spacing. The discharge coefficient increases with the increases of hole diameter and inclination angle, but decreases with the increases of blowing ratio, hole pitch and spacing. Pure film cooling and double-wall cooling were also compared. The introduction of jet impingement cooling can generate higher cooling effectiveness, especially at low and medium blowing ratio, but causes the notable increase of pressure drop. [ABSTRACT FROM AUTHOR]

In this paper, we study the weak convergence and convergence rate in the weak law of large numbers for weighted sums of a class of random variables satisfying the Rosenthal type inequality. The necessary and sufficient conditions for the convergence rates in the weak law of large numbers under some mild conditions are provided. Moreover, the main results that we established are applied to simple linear errors-in-variables regression models and nonparametric regression models based on a class of random errors. Finally, we present some numerical simulations to assess the finite sample performance of the theoretical results. [ABSTRACT FROM AUTHOR]

Image segmentation implementation provides simplified and effective feature information of image. Neural network algorithms have made significant progress in the application of image segmentation task. However, few studies focus on the implementation of hardware circuits with high-efficiency analog calculations and parallel operations for image segmentation problem. In this paper, a memristor-based competitive Hopfield neural network circuit is proposed to deal with the image segmentation problem. In this circuit, the memristive cross array is applied to store synaptic weights and perform matrix operations. The competition module based on the Winner-take-all mechanism is composed of the competition neurons and the competition control circuit, which simplifies the energy function of the Hopfield neural network and realizes the output function. Operational amplifiers and ABM modules are used to integrate operations and process external input information, respectively. Based on these designs, the circuit can automatically implement iteration and update of data. A series of PSPICE simulations are designed to verify the image segmentation capability of this circuit. Comparative experimental results and analysis show that this circuit has effective improvements both in processing speed and segmentation accuracy compared with other methods. Moreover, the proposed circuit shows good robustness to noise and memristive variation. [ABSTRACT FROM AUTHOR]