Coupling characteristic analysis of ship shafting design parameters and research on multidisciplinary design optimization

In the design process of traditional ship shafting, the design quality is generally hard to get guaranteed for the lack of discipline coupling. In this paper, Multidisciplinary Design Optimization (MDO) is innovatively introduced to ensure design quality. Multidisciplinary decomposition of shafting can help to construct the MDO model of ship shafting based on multidisciplinary feasibility method. Then the sub-discipline model of shifting design can be further established, including calibration neutron discipline model, whirling vibration model, and dynamic stiffness of radial oil film bearing model. Collaborative operation is implemented by the multidisciplinary model of shifting to obtain the experimental results. Based on Radial Basis Function (RBF) neural network, the responsive surfaces of variable, bearing load, and support stiffness can be constructed, in the meanwhile the dynamic stiffness decoupling of vibration model can be obtained. Fireworks algorithm is used to establish multidisciplinary optimization of seven-dimensional design variable. The results show that MDO helps improve the quality of shafting alignment and whirling vibration. The work in present paper also provides insight for the future optimization of research methods, design quality, and engineering experiments

New studies in convertible bond investment and financing

This series of paper studies convertible bond financing from the perspective of both issuers and investors. Based on an empirical study, convertible bond financing seems to be overused: it would appear that convertible bond financing should be dominated by sequential issues of straight bonds followed by new equity issues sometime thereafter. A new model is introduced to demonstrate that managers of all types of firms, irrespective of quality would choose convertible bonds in their financing plans when facing uncertainties about the timing of the project. Convertible bond issuance can be optimal for firms that do not have an established record of strong historical performance but have opportunity sets that include good projects subject to timing uncertainties. The first part of this study focuses on the investor perspective and investigates the returns of holding convertibles/underlying stocks, as well as the returns of convertible hedging strategies. Naked long position of convertible bonds from issuance date and hedging based on the characteristics of convertibles can derive good returns. Consequently, investors can benefit from both the upside expectation of convertible issuing firms and the structured terms of convertibles. Next, convertible bonds are studied from the perspective of issuer. Here, liquidity risk, firm risk, and issue risk premium factors are identified as determinants of abnormal returns around the convertible bond issue dates. The market responds favorably to firm volatility risk, but negatively to the liquidity risk and issue risk premium factors. The cumulative effects of these risks determine the abnormal returns of convertible bond

Millimeter-Waves Slot Array Antennas based on Gap Waveguide Technology

Recently, gap waveguide technology is introduced as a promising guiding structure for millimeter-wave systems. The conception of gap waveguide technology can be modeled for theoretical analysis by two parallel plates, a top perfect electric conductor layer and a bottom perfect magnetic conductor layer. This structure stops all modes propagating in all directions except for a quasi-TEM mode along the strip over a specic frequency band (stopband) when the gap between PEC and PMC plates is smaller than quarter wavelength at an operation frequency. Until now there are already four dierent versions of this novel conceptgroove, ridge, inverted microstrip and microstrip ridge gap waveguides. The proposed thesis mainly focuses on array antenna design based on gap waveguide technology. We present several low-prole single-layered and multilayer corporate-fed slot array antennas with high gain for the 60-GHz band and 140-GHz. The aim of this thesis is to demonstrate the advantages of gap waveguide technology as an alternative to the traditional lowloss waveguide structure to overcome the problem of good electrical contact due to mechanical assembly. Measurement results and experimental validation are provided for the presented antenna design

Slot Array Antennas at V-band based on Inverted Microstrip Gap Waveguide

Recently, gap waveguide technology is introduced as a proper guiding structure for millimeter-systems. The conception of gap waveguide technology can be modeled for theoretical analysis by two parallel plates, a top perfect electric conductor layer and a bottom perfect magnetic conductor layer. This structure stops all modes propagating in all directions except for a quasi-TEM mode when the gap between perfect electric conductor and perfect magnetic conductor plates is smaller than quarter wavelength at an operating frequency. Until now there are already four different visions of this novel conception-groove, ridge, inverted microstrip and microstrip ridge gap waveguides. Among those four structures, the inverted microstrip gap waveguide has same obvious advantages. First of all, it has a uniform bed of nails while the others do not. This uniform pin structure makes the fabrication much easier and cheaper. Secondly, fabrication of microstrip circuitry on PCB by etching is accurate and very low cost. In addition, theories and design principles of microstrip technologies are very well-developed. Therefore, my work in this Lic. thesis is focusing on the theory of inverted microstrip gap waveguide and its applications on millimeter wave array antenna design

Is Induced Abortion a Part of Family Planning in China?

Family planning policy is one of the basic policies in China. Since the founding of New China, it has gone through three stages during its development process, which include free fertility policy, one-child policy (including selective two-child policy), and universal two-child policy. The number of induced abortions in China has increased from 3,910,110 in 1971 to 9,626,731 in 2017, and the proportion of induced abortions in birth control surgeries of family planning in China has increased from 30.0% in 1971 to 50.6% in 2017. It is concluded that although induced abortion is not a part of the family planning policy of China, it has been a part of family planning services in China