A hybrid analytical model of sterilization effect on marine bacteria using microbubbles interacting with shock wave

The present paper reports on a hybrid analytical model consisting of a biological probability model and a physical impact model proposed to predict the cell viability ratio of a sterilization method for marine bacteria using microbubbles interacting with a shock wave. The physical impact model of interaction between a microbubble and a shock wave is developed on the basis of the bubble motion analysis with experimental pressure data and a one-dimensional numerical simulation. An underwater shock wave produced by microbubble motion is simulated using a second-order finite differential scheme by means of bubble surface velocity variation obtained from Herring’s bubble motion equation, and the radius of the sterilized space around a microbubble is estimated by the critical pressure that just causes cell wall damage of marine bacteria. The sterilization effect predicted by the present hybrid analysis shows a good agreement with the bio-experimental result.     

Convergence of different wake alignment methods in a panel code for steady-state flows

Wake alignment models are always included in the modern panel codes for marine propeller analysis. The wake alignment algorithms influence directly the rate of convergence and the accuracy of calculations. In the present work, firstly, four different numerical methods to implement the wake alignment algorithms for the steady calculation are described. They perform quite differently in terms of convergence history and convergence rate. The comparison with the other methods shows that the direct application of the unsteady method leads to a much slower convergence rate. Secondly, high-order numerical methods including second-order and fourth-order Runge–Kutta methods are introduced into the wake alignment, which results in high-order wake alignment algorithms. The analysis of the results shows that the high-order methods generate a different wake geometry from the low-order method. The thrust coefficient and torque coefficient have also been compared.     

Influence of the type of the pulverized coal concentrator on the operation of a tangential fired boiler with horizontal bias combustion

In this paper, the problems of combustion instability and high-temperature corrosion of pulverized coal fired boiler are investigated by numerical simulation and analysis of the momentum moment. Elbow and twisting plate type of burners are used in the boiler, and the reverse moment of momentum is formed at the outlet of the fuel-rich side of the burner. The momentum moment in the boiler is opposite to the designed tangential circle, and the tangential circle in the boiler is reversed rotation. The reverse moment of momentum at the burner outlet can be eliminated by using louver horizontal bias pulverized coal burner, while the problems of combustion instability and high-temperature corrosion of the boiler are solved, and the combustion efficiency is improved. Accordingly,economic benefit is obviously got.     

Wind turbine gearbox reliability analysis based on the system level stress-strength model

In order to estimate the reliability of wind turbine gearbox based on the system level, a generalized stress-strength model is introduced. Considering that the system works properly under a variety of random stresses which affect every component, the total stress on the system is given by a known linear combination of the stresses of all components. Then the strength of the system can be viewed as a linear combination of the strengths of relative components. In this model, stress and strength are independent of each other. Reliability of the system is the probability that strength exceeds stress. Finally, the reliability of wind turbine gearbox is estimated by the multivariable reliability calculation method. The corresponding result is compared with the results of reliability in the extreme cases(completely dependent and completely independent) by the traditional evaluation method.     

An improved modal strain energy method for damage detection in offshore platform structures

The development of robust damage detection methods for offshore structures is crucial to prevent catastrophes caused by structural failures. In this research, we developed an Improved Modal Strain Energy (IMSE) method for detecting damage in offshore platform structures based on a traditional modal strain energy method (the Stubbs index method). The most significant difference from the Stubbs index method was the application of modal frequencies. The goal was to improve the robustness of the traditional method. To demonstrate the effectiveness and practicality of the proposed IMSE method, both numerical and experimental studies were conducted for different damage scenarios using a jacket platform structure. The results demonstrated the effectiveness of the IMSE method in damage location when only limited, spatially incomplete, and noise-polluted modal data is available. Comparative studies showed that the IMSE index outperformed the Stubbs index and exhibited stronger robustness, confirming the superiority of the proposed approach.     

Incentivizing alternative fuel vehicles: the influence of transport policies,attitudes and perceptions

This paper aims to evaluate the influence of policies, attitudes and perceptions when incentivizing alternative fuel vehicles. The impact of possible policies such as gasoline taxes increases, purchase price subsidies, tax exemptions, and increases in fuel recharging station availability for alternative fuelled vehicles is evaluated using hybrid choice models. The models also allow assessing the sensitivity of latent variables (i.e., attitudes and perceptions) in the car purchase behaviour. The models are estimated using data from a stated choice survey collected in five Colombian cities. The latent variables are obtained from the rating of statements related to the transport system, environmental concern, vehicle preferences, and technology. The modelling approach includes regression between latent variables. Results show that environmental concern and the support for green transport policies have a positive influence on the intention to purchase alternative fuel vehicles. Meanwhile, people who reveal to be car-dependent prefer to buy standard fuelled vehicles. The analysis among cities shows similar trends in individual behaviour, although there are differences in attribute sensitivities. The policy scenario analysis revealed high sensitivity to capital cost and the need for extensive investments in refuelling stations for alternative fuel vehicles to become attractive. Nevertheless, all policies should not only be directed at infrastructure and vehicles but also be focused on user awareness and acceptance of the alternative fuel vehicles. The analysis suggests that in an environmentally conscious market, people prefer alternative fuels. However, if the transport policies support private transport, the market shares of alternative fuel vehicles will decrease.     

A Solution Processable Flexible Transparent Conductive Graphene/PEDOT: PSS Film Fabricated by Spin and Blade Coating

Flexible transparent conductive films were made on PET substrates by spin and blade coating, using graphene sheets dispersed in PEDOT: PSS solution. Ultrasonic substrate vibration was used to improve microstructure and properties of the films. Comparing to the pristine PEDOT: PSS film, the sheet resistance is 3 to 4 orders of magnitude lower with the addition of graphene. The conductivity and reproducibility of the film are improved for two-layer films comparing to one-layer films, with a reduction in transparency. Films prepared with substrate vibration showed lower sheet resistance for one-layer films, as the size of dewetting areas is reduced. In addition, large-area flexible films with desirable conductivity and transmittance were successfully fabricated by blade coating, which is promising, as the process is low-cost, scalable and compatible with roll-to-roll manufacturing.     

Polling algorithm based on traffic burst characteristics of broadband wireless access systems

In this paper, we propose a novel polling algorithm to decrease the number of idle slots and collission slots during the polling cycle by evaluating the bandwidth request of the subscribe stations (SSs) in the next polling cycle for broadband wireless access (BWA) systems. We firstly analyze the feature of silent time intervals and deduce the Hurst index which symbolizes the degree of self-similarity and long-relative nature. Then we represent the inactive OFF time intervals by the Pareto model and estimate the shape parameter α by the group measured data. Finally we can evaluate the transmission probability of a silent SS before the next polling cycle. By this algorithm, we can find the optimal transmission opportunities for the base station (BS) to achieve the least collision or void timeslots in order to achieve the largest bandwidth efficiency. The theoretical analysis and simulation results show that this polling algorithm can improve the performance for BWA system.     

Universal jurisdiction as obligation to prosecute or extradite

Before searching for new legal solutions to manage maritime piracy problems, especially those related to jurisdiction, it is essential to examine and analyse the existing international legal framework to determine whether current international legal instruments are already appropriate to face off this threat. One such principle is the “Aut dedere aut iudicare” principle, which has been also codified into SUA Convention, at art. 6 par. 4. This obligation comes from an international treaty, so it cannot be disregarded by any state (short of becoming susceptible to international liability), neither can it be amended by a national law. If a state party has inadequate law resources to establish its jurisdiction, or if unable or unwilling to prosecute the pirate, then such state party has no choice but extradite the pirate. If we consider the above principle as a conventional obligation, then it should be limited only to state parties, and it should be applied only under conditions stated by SUA Convention. Instead, if we consider it as a customary law principle, because piracy—as crimen iuris gentium—offends international community as a whole, then such principle shall be binding without any limit or condition.     

A novel de-noising method based on discrete cosine transform and its application in the fault feature extraction of hydraulic pump

Aiming at the existing problems of discrete cosine transform (DCT) de-noising method, we introduce the idea of wavelet neighboring coefficients (WNC) de-noising method, and propose the cosine neighboring coefficients (CNC) de-noising method. Based on DCT, a novel method for the fault feature extraction of hydraulic pump is analyzed. The vibration signal of pump is de-noised with CNC de-noising method, and the fault feature is extracted by performing Hilbert-Huang transform (HHT) to the output signal. The analysis results of the simulation signal and the actual one demonstrate that the proposed CNC de-noising method and the fault feature extraction method have more superior ability than the traditional ones.