Experimental study of a domestic thermoelectric cogeneration system

Thermoelectric application for power generation does not appear to be appealing due to the low conversion efficiency given by the current commercially available thermoelectric module. This drawback inhibits its wide application because of the overall low thermal efficiency delivered by typical thermoelectric applications. This paper presents an innovative domestic thermoelectric cogeneration system (TCS) which overcomes this barrier by using available heat sources in domestic environment to generate electricity and produce preheated water for home use. This system design integrates the thermoelectric cogeneration to the existing domestic boiler using a thermal cycle and enables the system to utilise the unconverted heat, which represents over 95% of the total absorbed heat, to preheat feed water for domestic boiler. The experimental study, based on a model scale prototype which consists of oriented designs of heat exchangers and system construction configurations. An introduction to the design and performance of heat exchangers has been given. A theoretical modelling for analysing the system performance has been established for a good understanding of the system performance at both the practical and theoretical level. Insight has also been shed onto the measurements of the parameters that characterise the system performance under steady heat input. Finally, the system performance including electric performance, thermal energy performance, hydraulic performance and dynamic thermal response are introduced.     

Investigation on twisting distortion of thin plate stiffened structure under welding

The welding distortion of thin plate was selected as research subject, which causes loss of dimensional control, structural integrity and increases fabrication costs for straightening. To study the characteristic of the welding distortion on thin plate structures, experiments were conducted. The test model was a thin plate stiffened structure and a large twisting distortion was observed. The welding distortion of the same structure was analyzed as a large deformation problem using a thermal elastic plastic FEM and an elastic FEM based on the concept of inherent deformation. The computed results by both methods showed the twisting distortion which is a typical buckling type deformation and the magnitude of this distortion agreed well with the experimental measurement.     

Wave climate analysis for the design of wave energy harvesters in the Mediterranean Sea

The objective of this paper is to provide a synthetic tool for determining expeditiously the wave climate conditions in several areas of the Mediterranean Sea. In the open literature, several authors have already conducted this specific analysis also for the area under examination in this paper. However, the need of discussing aspects strictly related to the design of wave energy harvesters is still relevant. Therefore, considering the variety of devices and the amount of information needed for conducting both an energy-wise optimization and a structural reliability assessment, a holistic view on the topic is provided. Specifically, the paper elucidates the theoretical aspects involved in the estimation of wave energy statistics and in the calculation of relevant return values. Next, it provides synthetic data representing the mean wave power and the return value of extreme events in several coastal areas of the Mediterranean Sea. In this regard, the paper complements information available in the open literature by discussing the influence of the directional pattern of the sea states in the determination of sea state statistics as well as in the design of a wave energy harvester.     

The effects of wind-induced inclination on the dynamics of semi-submersible floating wind turbines in the time domain

This study focusses on the coupling effects arising from the changes in the hydrodynamic behaviour of a semi-submersible floating wind turbine when it undergoes large inclinations under wind loading. By means of a range of time-domain simulations, it is shown that both the hull geometric nonlinearity effect and the alteration of viscous hydrodynamic forces can significantly affect the dynamics of a typical floating wind turbine operating in waves at rated conditions. The consequences of said effects for both aligned and misaligned wind and waves are explored. In general terms inclinations are found to increase motions, where the modes that are more affected depend on the relative direction between incident wind and waves. Understanding the sources of aero-hydrodynamic coupling is key to providing sound design and modelling guidelines for the coming generation of floating wind turbines.     

Student cluster competition: ParConnect reproducibility task report

Reproducibility is a desirable characteristic of any experimental work in computer science. In this paper, we reproduce the results in the paper, “A parallel connectivity algorithm for de Bruijn graphs in metagenomic applications”, for verifying their claims on the speed and scalability of their algorithm. We first state the claims made in the original paper. Then, we describe our hardware and software setup used for the reproducibility task, followed by the steps taken to setup the proposed algorithm and profiling software. Lastly, we present the results obtained from our experiments and show that we are able to reproduce most of the claims made in the original paper.     

Dependency solving: A separate concern in component evolution management

Maintenance of component-based software platforms often has to face rapid evolution of software components. Component dependencies, conflicts, and package managers with dependency solving capabilities are the key ingredients of prevalent software maintenance technologies that have been proposed to keep software installations synchronized with evolving component repositories. We review state-of-the-art package managers and their ability to keep up with evolution at the current growth rate of popular component-based platforms, and conclude that their dependency solving abilities are not up to the task.We show that the complexity of the underlying upgrade planning problem is NP-complete even for seemingly simple component models, and argue that the principal source of complexity lies in multiple available versions of components. We then discuss the need of expressive languages for user preferences, which makes the problem even more challenging.We propose to establish dependency solving as a separate concern from other upgrade aspects, and present CUDF as a formalism to describe upgrade scenarios. By analyzing the result of an international dependency solving competition, we provide evidence that the proposed approach is viable.     

Compressive properties and energy absorption of aluminum foams with modified cellular geometry

This study presents experimental results on the behavior of aluminum alloy metal foams with controlled pore morphology in compression. Two types of metal foams were analyzed, having uniform cell structure and with a dual-size cell arrangement seeking optimized mechanical properties. The structures were manufactured by lost-wax casting using 3D printed components for internal structure definition. Results for stiffness and energy absorption were obtained and compared on weight efficiency basis. The results are indicative of higher efficiency of the dual-size structures that may be considered for use in components subjected to impact or compression loading.     

Adaptive signal processing algorithms for creating spatial zones of quiet

Available adaptive active noise control (ANC) algorithms can only minimize the noise level at a point that an error microphone is placed. Consequently, a zone of quiet around this microphone is produced as a byproduct. However, they cannot technically control or, even, monitor the noise level within the zone of quiet unless they use several sensors. They cannot also control the shape and the extension of the quiet zone by using only the error microphone. This paper develops a signal processing framework for the derivation of adaptive ANC algorithms that can directly create a controllable zone of quiet in monochromatic noise fields using a single error microphone. It is shown that by adding a filter to the standard ANC structure, a controllable zone of quiet is created. The transfer function of this filter is obtained using an accurate mathematical analysis. It is also shown that the extension of the zone of quiet can be controlled by tuning this filter. The implementation of the proposed system requires no additional hardware, rather than those required for traditional ANC systems. The validity of the results are discussed by using numerical analysis. Also, the performance of the proposed system is practically verified.     

The analysis of damage degree of oil and gas pipeline with type II plain dent

Dent is a common type of defect in oil and gas pipelines and the assessment on dented pipelines is carried out with major international standards and specifications based on dent depth as the evaluation criteria. However, such evaluation criteria based on depth does not account for the impact of various parameters (e.g. parameters of dent, parameters of pipeline and the internal pressure of pipeline) on the evaluation result, as a result, many dented pipelines lose their efficacy, even though they meet the depth-based standards. The influence of parameters changes on the damage degree of II-type dented pipelines is investigated on the basis of Oyane's ductile fracture criterion and by the method adopting finite element numerical calculations. Finally, the non-linear regression analysis is conducted and based on the outputs, a specific expression of dent depth and pipeline damage degree is also acquired within a certain scope of application.     

Approach for fatigue damage assessment of welded structure considering coupling effect between stress and corrosion

This paper presents a new approach to assess time-dependent corrosion fatigue damage of welded joint considering the coupling effect between mechanical factor and corrosion factor. The high stress region around weld will accelerate corrosion and be more likely to induce nonuniform corrosion of welded joint. And the effect of loading on corrosion behavior of the steel in NaCl solution was investigated. The synergistic effect between applied elastic stress and chemical attack on Q235 steel was evaluated by electrochemical experiments. A side longitudinal of ship structure is selected as a case study. Time-dependent stress concentration factor of welded joint as a function of corrosion deterioration was analyzed, and the iterative process of stress and corrosion degeneration of plate thickness was used to simulate coupling effect basing on the results of experiment. The hot spot stress approach was adopted to calculate the fatigue damage. It is revealed that the nonuniform corrosion could influence fatigue damage of welded joint, and that impact will be more and more significant with the growth of corrosion year.