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Open access

Lingjie Zhang, Jianbo Sun and Chen Guo

Abstract

A novel multi-objective discrete particle swarm optimization with elitist perturbation strategy (EPSMODPSO) is proposed and applied to solve the reconfiguration problem of shipboard power system(SPS). The new algorithm uses the velocity to decide each particle to move one step toward positive or negative direction to update the position. An elitist perturbation strategy is proposed to improve the local search ability of the algorithm. Reconfiguration model of SPS is established with multiple objectives, and an inherent homogeneity index is adopted as the auxiliary estimating index. Test results of examples show that the proposed EPSMODPSO performs excellent in terms of diversity and convergence of the obtained Pareto optimal front. It is competent to solve network reconfiguration of shipboard power system and other multi-objective discrete optimization problems.

Open access

Zheshu Ma, Hua Chen and Yong Zhang

Abstract

The increase of ship’s energy utilization efficiency and the reduction of greenhouse gas emissions have been high lightened in recent years and have become an increasingly important subject for ship designers and owners. The International Maritime Organization (IMO) is seeking measures to reduce the CO2 emissions from ships, and their proposed energy efficiency design index (EEDI) and energy efficiency operational indicator (EEOI) aim at ensuring that future vessels will be more efficient. Waste heat recovery can be employed not only to improve energy utilization efficiency but also to reduce greenhouse gas emissions. In this paper, a typical conceptual large container ship employing a low speed marine diesel engine as the main propulsion machinery is introduced and three possible types of waste heat recovery systems are designed. To calculate the EEDI and EEOI of the given large container ship, two software packages are developed. From the viewpoint of operation and maintenance, lowering the ship speed and improving container load rate can greatly reduce EEOI and further reduce total fuel consumption. Although the large container ship itself can reach the IMO requirements of EEDI at the first stage with a reduction factor 10% under the reference line value, the proposed waste heat recovery systems can improve the ship EEDI reduction factor to 20% under the reference line value.

Open access

Chen Zhang, Fangxu Chen, Zhixin Ling, Gang Jian and Yuanliang Li

Abstract

Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics, prepared by solid state method, were investigated with non-stoichiometric level and various La2O3 content, using XRD, SEM and LCR measuring system. With an increase of non-stoichiometric level, the unit cell volumes of perovskite lattices for the single phase Ti-rich barium strontium titanate ceramics increased due to the decreasing A site vacancy concentration V″A. The unit cell volume increased and then decreased slightly with the increasing La2O3 content. Relatively high non-stoichiometric level and high La2O3 content in Ti-rich barium strontium titanate ceramics contributed to the decreased average grain size as well as fine grain size distribution, which correspondingly improved the temperature stability of the relative dielectric constant. The relative dielectric constant єrRT, dielectric loss tanδRT and the maximum relative dielectric constant єrmax decreased and then increased with the increasing non-stoichiometric level. With the increase of La2O3 doping content, the relative dielectric constant єrRT increased initially and then decreased. The maximum relative dielectric constant єrmax can be increased by applying low doping content of La2O3 in Ti-rich barium strontium titanate ceramics due to the increased spontaneous polarization.

Open access

Si Chen, Xue-pei Zhang, Hong-xia Chen and Xiao-ping Gao

Abstract

The present work has reported the compression properties of polyurethane-based warp-knitted spacer fabric composites (PWSF). In order to investigate the effect of structural parameters of fabric on the compression performance of composites, a series of warp-knitted spacer fabrics (WSF) with different structural parameters including spacer yarn inclination angle, thickness, fineness of spacer yarns, and outer layer structure have been involved. The produced composites have been characterized for compression properties. The energy-absorption performance during the compression process has been determined as a function of the efficiency and the compression stress obtained from compression tests. The results show that the composites based on spacer fabrics having smaller spacer yarns inclination angle, higher fabric thickness, finer spacer yarn, and larger mesh in outer layers perform better with respect to energy-absorption properties at lower stress level, whereas at higher stress level, the best energy-absorption abilities are obtained in case of spacer fabrics constructed of larger spacer yarn inclination angle, lower fabric thickness, coarser spacer yarn, and smaller mesh in surface layers.

Open access

Rui-dan Zheng, Zhuo-ran Chen, Jian-neng Chen and Hui-yong Zhang

Abstract

A 34-year-old man with no history of any abdominal pain or fatigue was admitted to our hospital in June 2008 due to the cirrhosis found incidentally during a physical examination. Laboratory examination, electrocardiograph, abdominal ultrasonography and magnetic resonance imaging were carried out during his hospitalization. However, according to the results of the above measures, the diagnosis of nodular regenerative hyperplasia of the liver (NRHL) could not be made. The result of electrocardiograph showed there was no sinus bradycardia. The abdominal ultrasonography showed evidence of hepatosplenomegaly, and magnetic resonance imaging showed multiple non-enhancing hepatic nodules. Histologic confirmation was available by means of liver biopsy and the definitive diagnosis of NRHL was confirmed histologically by liver biopsy. NRHL always presents with signs of portal hypertension with little evidence of obvious liver disease, NRHL may mimick the cirrhosis of liver and be easily confused with cirrhosis of the liver nodules, so liver biopsy should be recommended for correct diagnosis. We here report the clinical, radiological and pathologic features of this case with NRHL in order to familiarize the physicians with its clinical manifestations.

Open access

Chunguan Zhang, Jingguo Chen, Mingyi Song, Jinkuan Wang and Bingqiang Yuan

Abstract

The Qingdong area, located in Bohai bay basin, was suspected good exploration prospects. In order to study tectonic features and find out favourable petroleum prospects in the area, the gravity data at a scale of 1:50,000 were interpreted. This paper, through data processing and synthetic interpretation of the high-precision gravity data in the area, discusses characteristics of the gravity field and their geological implications, determines the fault system, analyses features of the main strata, divides structure units and predicts favourable petroleum zones. The results showed that the faults controlled the development of the Mesozoic and Cenozoic strata and the distribution of local structures in this area. The study revealed that the Qingtuozi uplift and the Kendong uplift in the north were formed in Mesozoic, and the Qingdong depression in the middle was the rift basin in Mesozoic and Cenozoic. Thicker strata in Mesozoic and Cenozoic developed in the Dongying depression and the Qingdong depression, so there is abundant hydrocarbon in these two depressions, and then the Guangligang rise-in-sag and the Qingdong rise-in-sag developed in the center in these two depressions are also favorable places for prospecting

Open access

Jinling Chen, Hongbin Li, Mingming Zhang and Yan Zhang

Abstract

A novel magneto-optical current sensor (MOCS) with two sensing arms is proposed to improve the temperature stability. One of the arms, with a highly stable permanent magnet attached and orthogonal to the other one, is designed to provide a reference that follows the temperature characteristics of the sensing material. By a normalization operation between two arms, the temperature drift is compensated adaptively and a sensing output proportional to the measured current can be reached. A dual-input and dual-output structure is specially designed for the reference sensing arm to demodulate the DC Faraday rotation angle. This scheme compensates simultaneously two main temperature influence factors, the Verdet constant and linear birefringence. Validation tests were carried out and are discussed.