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Maritime shipping is a key component of the global economy, representing 80–90% of international trade. To deal with the energy crisis and marine environmental pollution, hydrogen-natural gas-diesel tri-fuel engines have become an attractive option for use in the maritime industry. In this study, numerical simulations and experimental tests were used to evaluate the effects of different hydrogen ratios on the combustion and emissions from these engines. The results show that, in terms of combustion performance, as the hydrogen proportion increases, the combustion ignition delay time in the cylinder decreases and the laminar flame speed increases. The pressure and temperature in the cylinder increase and the temperature field distribution expands more rapidly with a higher hydrogen ratio. This means that the tri-fuel engine (H2+CH4+Diesel) has a faster response and better power performance than the dual-fuel engine (CH4+Diesel). In terms of emission performance, as the hydrogen proportion increases, the NO emissions increase, and CO and CO2 emissions decrease. If factors such as methane escape into the atmosphere from the engine are considered, the contribution of marine tri-fuel engines to reducing ship exhaust emissions will be even more significant. Therefore, this study shows that marine hydrogen-natural gas-diesel tri-fuel engines have significant application and research prospects.

The seakeeping behavior of a ship in waves is different from its behavior in calm water. The resistance and seakeeping performance of a ship are of great importance and must be considered in the early-stage design of a ship’s hull form design. Therefore, this paper proposes a hull form optimization framework aiming to achieve the minimum total resistance in waves using a CFD technique. A sinusoidal wave is adopted to establish the numerical wave tank and the overset mesh technique is used to facilitate the motions of the ships in question. Considering the motions of pitching and heaving, the total resistance of the hull in waves is regarded as the objective function which is calculated using the Reynolds averaged Navier–Stokes (RANS) method. The arbitrary shape deformation (ASD) technique is used to change the geometry. Under displacement and design variables, a hybrid algorithm is developed to evaluate the objective function combining the optimal Latin hypercube design (Opt LHD) and the non-linear programming by quadratic Lagrangian (NLPQL) algorithm. Finally, two examples of hull form optimization are presented and discussed for David Taylor Model Basin (DTMB) model 5512 and WIGLEY III cases. The results show the effectiveness of the optimization framework developed in the present study, which can lay the foundation for further optimization of full-scale ships.

Based on the theoretical analysis about ultrasonic wave’s reflection and refraction coefficient at ceramic-oil interface (COI) and ceramic-air interface (CAI), the paper studies the ultrasonic echo characteristics at COI and CAI of oil-filled porcelain cable termination(OFPCT) by experiments. The study shows that under the same condition, the first interface echo height of ultrasonic at COI is about 2dB higher than that at the COI, which can be easily inundated by defective coupling. However, the difference of the amplitude of echo attenuation and the echo times at two interfaces is relatively obvious. Based on the experimental result, the paper puts forward the ultrasonic method to detect oil level of OFPCT.

The infrared thermal image is an importance in condition monitoring of electrical equipment. However, the infrared image edge is coarse, fuzzy, and with serious noise and brings great inconvenience to the infrared image processing. An adaptive optimal threshold edge extraction algorithm based on improved Sobel operator is proposed in this paper. In the algorithm, by eight-direction Sobel operators the infrared image edge is extracted in the high temperature area in noisy environment. At the same time, the wavelet coefficients in sub-band are described by general Gaussian distribution and the variance is estimated from the local neighborhood information of sub-band wavelet coefficients so that the adaptive optimal denoising threshold can be obtained. Finally, the edge extraction infrared image is denoised by combining with improved Sobel operator and the optimal threshold. Matlab simulation results show that the algorithm can effectively detect the edge of infrared image and greatly improve its anti-noise ability.

In order to reduce the total resistance of a hull, an optimization framework for the bulbous bow optimization was presented. The total resistance in calm water was selected as the objective function, and the overset mesh technique was used for mesh generation. RANS method was used to calculate the total resistance of the hull. In order to improve the efficiency and smoothness of the geometric reconstruction, the arbitrary shape deformation (ASD) technique was introduced to change the shape of the bulbous bow. To improve the global search ability of the particle swarm optimization (PSO) algorithm, an improved particle swarm optimization (IPSO) algorithm was proposed to set up the optimization model. After a series of optimization analyses, the optimal hull form was found. It can be concluded that the simulation based design framework built in this paper is a promising method for bulbous bow optimization.

With the rapid development of the computational technology, computational fluid dynamics (CFD) tools have been widely used to evaluate the ship hydrodynamic performances in the hull forms optimization. However, it is very time consuming since a great number of the CFD simulations need to be performed for one single optimization. It is of great importance to find a high-effective method to replace the calculation of the CFD tools. In this study, a CFD-based hull form optimization loop has been developed by integrating an approximate method to optimize hull form for reducing the total resistance in calm water. In order to improve the optimization accuracy of particle swarm optimization (PSO) algorithm, an improved PSO (IPSO) algorithm is presented where the inertia weight coefficient and search method are designed based on random inertia weight and convergence evaluation, respectively. To improve the prediction accuracy of total resistance, a data prediction method based on IPSO-Elman neural network (NN) is proposed. Herein, IPSO algorithm is used to train the weight coefficients and self-feedback gain coefficient of ElmanNN. In order to build IPSO-ElmanNN model, optimal Latin hypercube design (Opt LHD) is used to design the sampling hull forms, and the total resistance (objective function) of these hull forms are calculated by Reynolds averaged Navier–Stokes (RANS) method. For the purpose of this paper, this optimization framework has been employed to optimize two ships, namely, the DTMB5512 and WIGLEY III ships, and these hull forms are changed by arbitrary shape deformation (ASD) technique. The results show that the optimization framework developed in this study can be used to optimize hull forms with significantly reduced computational effort.

The aim of this study was to observe the changes in glucose metabolism after antipsychotic (APS) therapy, to note the influencing factors, as well as to discuss the relationship between the occurrence of glucose metabolism disorders of APS origin and abnormal glycosylated hemoglobin (HbA1c) levels. One hundred and fifty-two patients with schizophrenia, whose fasting plasma glucose (FPG) and 2-h plasma glucose (2hPG) in the oral glucose tolerance test (2HPG) were normal, were grouped according to the HbA1c levels, one normal and the other abnormal, and were randomly enrolled into risperidone, clozapine and chlorpromazine treatment for six weeks. The FPG and 2hPG were measured at the baseline and at the end of the study. In the group with abnormal HbA1c and clozapine therapy, 2HPG was higher after the study [(9.5 ± 1.8) mmol/L] than that before the study [(7.2 ± 1.4) mmol/L] and the difference was statistically significant (P0.01). FPG had no statistically significant difference before and after the study in any group (P0.05). HbA1c levels and drugs contributing to 2HPG at the end of study had statistical cross-action (P0.01). In the abnormal HbA1c group, 2HPG after the study was higher in the clozapine treatment group [(9.5 ± 1.8) mmol/L] than in the risperidone treatment group [(7.4 ± 1.7) mmol/L] and the chlorpromazine treatment group [(7.3 ± 1.6) mmol/L]. The differences were statistically significant (P0.01). In the normal HbA1c group there was no statistically significant difference before and after the study in any group (P0.05). 2HPG before [(7.1 ± 1.6) mmol/L] and after the study [(8.1 ± 1.9) mmol/L] was higher in the abnormal HbA1c group than in the normal HbA1c group [(6.2 ± 1.4) mmol/L vs (6.5 ± 1.4) mmol/L] with the difference being statistically significant (P0.01 vs P0.001). As compared with normal HbA1c group, the relative risk (RR) of glucose metabolism disease occurrence was 4.7 in the abnormal HbA1c group with the difference being statistically significant (P0.001). Patients with abnormal HbA1c are more likely to have a higher risk of having glucose metabolism disorders after APS treatment.

This paper makes a further research on fault diagnosis of marine engine cooling system based on artificial neural network (ANN). Firstly, it introduces the basic principle of ANN. The following section goes to describe the back propagation (BP) algorithm of neural network, basic structure of BP network and learning algorithm in detail. Finally, BP algorithm is used to detect and diagnose faults of marine engine cooling system. The research results are satisfactory and indicate that the network is simple in structure and good in speed of learning and adaptability.

To simulate human action in virtual environment of marine engine room, Software Creator and Vega of Multigen-Paradigm, and DI-Guy virtual human module of Boston Dynamics Inc. are introduced to construct the virtual human operation in Virtual Roaming System of marine engine room, body model in DI-Guy is modified, the action model on the hand part is intensified and collision detection of virtual human in real-time movement is studied. Thus real-time operations of virtual marine engineers in virtual engine room environment are realized, including operations of central control console in central control room, assembly, disassembly and maintenance of equipment parts, etc. The result indicates that this method can better simulate the engine room environment, help trained marine engineers knowing more about equipment layout and operations in the engine room, and improve the effectiveness of seafarers training.