Application of short time energy analysis in monitoring the stability of arc sound signal

This paper employed the short time energy of arc sound signals to online quantitatively describe the stability of arc sound signal. At first the signal can be preprocessed by wavelet packet filtering and then detailed information of the short time energy of the signal was obtained using hamming window. After statistical analyzed the short time energy the energy distribution possibility and cumulative distribution function of the signal can be collected. Then a proposed stability evaluation criterion was employed to quantitatively describe the stability of arc sound signal. Relative experimental data showed that more stable signal corresponded lager value of the criterion. The proposed method which combined the short time energy and statistical analysis was supported by many actual experiments. This contribution can benefit the quantitative evaluation of the arc welding process and instructed the future parameters optimization to obtain welding products with high quality. (C) 2017 Elsevier Ltd. All rights reserved

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Tidal and sediment dynamics in a fine-grained coastal region: A case study of the Jiangsu coast

The Jiangsu coast is located in eastern China bordering the South Yellow Sea. It is strongly affected by the semi-diurnal tides. Both the tidal range and the tidal current vary greatly in space due to local tidal wave systems and morphologies. The radial tidal current pattern identified at the central coast is suggested to play a primary role in the evolution of a large-scale radial-shape sand ridge system. Another feature of the Jiangsu coast is the diversity of the bottom sediments with pronounced silt content. Inspired by the characteristics of both the hydrodynamics and sediment dynamics throughout the Jiangsu coast, this thesis focuses on advancing our understanding of the coastal tidal dynamics and the resulting sediment transport. Regarding the radial tidal current pattern at the central Jiangsu coast, there have been plenty of studies exploring relevant formation mechanisms. A generally accepted inference is that the radial tidal current pattern is a consequence of the interaction between the northern rotating tidal wave system and the southern progressive tidal wave. In this study, we examine the emergence of the radial tidal current in a schematized semi-enclosed tidal basin by introducing the tidal Current Amphidromic Point (CAP) and the tidal current inclination angles. After comprehensive numerical experiments, we find that the overall basin scale and the cross-basin phase difference play roles in the emergence of the radial tidal current. The radial tidal current only has an opportunity to emerge in a basin where the basin length (L) is larger than width (B) (i.e. L/B>1), a lateral depth difference exists or the offshore incoming tidal wave has an oblique angle. The Yellow Sea is featured by these aforementioned prerequisites favouring the emergence of the radial tidal current. Furthermore, we discover that the radial tidal current is related to the cross-basin CAP distribution pattern. When the radial tidal current emerges, the focal point is the CAP related to the velocity vectors rotating anti-cyclonically in the Northern Hemisphere. The CAP distribution deserves more attention for the identification of the radial tidal current pattern. To understand the sediment dynamics in a silt-enriched environment in more detail, we have carried out a series of flume experiments under various wave and current conditions with field-collected silt-sand mixtures. According to the experiments, we find that the silt fraction has different features originating from both the sand fraction and the clay fraction. A high concentration layer is observed near the bottom together with ripples under pure wave conditions. Sediment concentrations inside the high concentration layer are quasi-stationary with the bulk Richardson number approaching a constant value. The thickness of the high concentration layer can be scaled with approximately two times the damped wave boundary layer thickness. Thus, the wave motion induced turbulence is considered to be the main reason generating the high concentration layer. Moreover, suspensions inside the high concentration layer have a certain amount of sand content, which is different from the fluid mud in the cohesive muddy bed. For the vertical concentration profile, the silt fraction is also distributed differently from the sand fraction, since the silt concentration decreases logarithmically within high concentration layer, while it is homogeneously distributed outside the high concentration layer. Considering the specific features of the silt fraction, we recalibrated the formulations of van Rijn (2007a, b) based on our experiments and further developed a multi-fraction sediment transport model to predict the vertical concentration profile for silt and sand classes, and then tested the existing sediment formulations. The results show a promising agreement with the measurements, for both wave-only and wave-with-current conditions. Finally, the Jiangsu Regional Model is set up utilizing the aforementioned findings on tides and sediments. The Jiangsu Regional Model is used to examine whether our existing knowledge can be integrated for a relatively long-term (i.e. time scale of years) predictions on the sediment transport and the morphological changes of the Jiangsu coast. To this end, we first reasonably construct the bed composition throughout the model domain. Subsequently, the model is calibrated and validated against two independent measurements on water level, flow velocity and the sediment concentration. The results indicate that the present model can produce good results. The simulated annual-averaged SSCs depict a high value in the coastal region between the Old Yellow River Delta and the northern Radial Sand Ridge Field. The simulated morphological changes show a spatially distributed alternating-erosion-sedimentation pattern in the Old Yellow River Delta rather than pure erosion. Over the Radial Sand Ridge Field, the ridges are continuously growing and the adjacent tidal channels are deepening. The simulated annual-averaged tide-induced sediment budget shows that the northern (i.e. the Old Yellow River Delta) and southern (i.e. the southern Radial Sand Ridge Field) Jiangsu coast are under erosion, while the central coast (i.e. the northern and central Radial Sand Ridge Field) is still in progradation. Furthermore, the simulated sediment bed in the Old Yellow River Delta shows a gradually coarsening trend while an overall fining trend is pronounced in the northern Radial Sand Ridge Field. All these long-term results are in good agreement with observation-based estimations. The present modelling framework indeed has the ability for simulating sediment transport and morphological changes over a relatively long time span (i.e. time scale of years). This thesis addresses series of findings on the radial tidal current pattern, characteristics of the silt-dominated sediments as well as the sediment transport and morphological changes along the Jiangsu coast. The proposed modelling approaches can serve as a basis and provide information on large-scale hydrodynamics and sediment dynamics for the management and planning of the Jiangsu coast. Future studies may be focused on (1) detailed investigation on the influencing factors on the emergence of the radial tidal current by the CAP system distribution; (2) the physics of the layered-bed system (i.e. the hard layer under ripples) for silt dominated mixtures; (3) improving the computational efficiency of the Jiangsu Regional Model for longer time scale (i.e. tens of years).Hydraulic EngineeringCivil Engineering and Geoscience

Exploring factors influencing visual comfort in an aircraft cabin

Visual stimulus might influence comfort of passengers in air travel. For a better understanding of the visual comfort, it is crucial to identify the constructs of the visual stimulus in the cabin and the contributions of different elements. A two-step approach was adopted in this study where in the first step, several creative sessions were executed for exploring the effect of different elements in the cabin regarding their impact on visual comfort. To inspire the participants, all creative sessions were held in a Boeing 737 cabin where participants were free to explore and had an immersive experience. All identified elements in the creative session were collected and grouped to different categories, that is use as input for the second step, which is an online survey investigating a possible hierarchy of the impact of those categories of elements on visual comfort. Eight were summarized and the three most influential categories were lighting, colour and the space arrangement. These were significantly different from other categories, namely the seat shape, the pattern, the windows, accessories and existence of advertisements. Regarding the gender and the age of the participants, we did not find significant differences regarding the preferences.Mechatronic DesignMaterials and Manufacturin

Effect of scent on comfort of aircraft passengers

BACKGROUND: Scents may influence the perceived comfort of an environment. There are only a few studies conducted on the relationship between scent and comfort in aircraft cabin. OBJECTIVES: The goal of this research is to explore whether relationships between scents and perceived comfort can be found for passengers in an aircraft cabin. METHODS: 276 participants joined an experiment in a Boeing 737 fuselage. The participants were divided into nine groups and each joined a session for 60 minutes with the exposure to different scents. The effect of the odor was measured by a set of questionnaires at the beginning and at the end of the session. Results of questionnaires were analyzed regarding the effects on the completion time, of the type of scents, of the intensity of the scent and on gender. RESULTS: Significant differences were found at the beginning and at the end of the experiment regarding comfort and emotion, but sometimes no relations could be established. The influence of different scents on comfort/discomfort varied and changed over time. However, in all scenarios, participant' scores on emotion decreased. Additionally, the added scents influenced the linearity between the changes in comfort and discomfort. CONCLUSIONS: Smell could influence the perceived comfort/discomfort of aircraft passengers over time, and different types of smells have different effects on passengers. The preferences on scents are diverse, which highlights the need for personalization in aircraft cabin design.Mechatronic DesignMaterials and Manufacturin

Near-infrared optical coherence tomography for the inspection of fiber composites

Optical coherence tomography (OCT) is a non-invasive imaging method, which allows the econstruction of three dimensional depth-resolved images with microscale resolution. Originally developed for biomedical diagnostics, nowadays it also shows a high potential for applications in the field of non-destructive testing (NDT). This work demonstrates how OCT could help to investigate the delamination growth in fiber composites. A customized OCT system was built with a near-infrared light source with center wavelength at 1550 nm. It was used as an inline NDT tool to monitor the crack tips and image the crack surfaces within a glass fiber composite under static loading. For carbon fiber composites, although it is difficult to acquire the internal structures due to their opaque property, OCT can still work as a surface profilometer to reconstruct 3D crack surface profiles, providing substantial information for the study of crack growth in the composites.Aerospace Structures and MaterialsAerospace Engineerin

Effective roughness height in high-concentrated flows

The effective roughness height is an important parameter in coastal sediment transport models. It has been extensively investigated in the past but few research results are related to the high-concentrated flows which often occur in a silty coast. A series of experiments has been carried out in a wave-current flume with silt-sized sediment bed. The mean velocity profiles were measured under different combined wave-current conditions. The effective roughness heights were calculated based on the curve fitting of measured velocity profiles by following the velocity profile model of You (1994). The accuracy of three empirical models, namely, Grant and Madsen (1982), Li and Amos (1998) and You (1996) was examined with the 'measured' effective roughness heights. The results show that all the models are not much accurate for the high-concentrated flows, particularly in the case with a relatively small sediment size. Therefore, cautions should be taken when applying those models in the silty coast, particularly during the extreme events.Coastal Engineerin

Sitting comfort in an aircraft seat with different seat inclination angles

Passengers' comfort experience during flights is important in choosing their flights. The focus of this study is passengers’ perceived comfort in different climbing angles during ascent. Twenty-six participants were invited to experience three inclination angles including 3°, 14° and 18° in a Boeing 737 cabin. The angle of 3° was used to simulate cruising stage and the other two were used to simulate different climbing angles. Participants experienced each setting for 20 min where the perceived comfort, their heart rate variability(HRV), and their body contact pressure values on the backrest and seat pan were recorded with questionnaires, HRV bands and pressure mats respectively. The results indicate a preference of 14° inclination angle resembling the cruising angle (3°) and having the slowest moving speed of the center of pressure (COP) on both the backrest and seat pan.Industrial Design EngineeringEmerging Material

Exploratory morphodynamic hindcast of the evolution of the abandoned Yellow River delta, 1578-1855

The Abandoned Yellow River Delta (AYD), which formed when the Yellow River flowed into the Southern Yellow Sea between 1128 and 1855 AD, is a representative example of the sensitivity of deltas to modifications in their environments. In this study, we established a process-based morphodynamic model to explore the morphological evolution of one such largescale fine-grained delta (the AYD before 1855). The uncertainties in the model settings, which are inevitable when historical data are insufficient, were assessed together with the corresponding influences on the evolution of the deltaic system by considering a series of scenarios. The results indicate that the strength of local tidal forcing is the key factor that determines the shape and evolutionary trend of the delta. Sediment input discharge and the slope of the initial coastal profile have a considerable effect on the overall size of the delta and the relative ratio between subaerial and subaqueous parts of the delta, respectively. Based on the evaluation of the uncertainties and a comparison with historical maps, the simulated AYD was evaluated to be reliable. Through an analysis of the temporal delta evolution and residual sediment transport, the morphological evolution of the AYD before 1855 AD was investigated. The southern delta grew as the shoals merged with the mainland, which is in agreement with an existing hypothesis (Zhang, 1984), whereas the accretion of the northern delta was independent from the shoals in the northern part. Additionally, suggestions are made regarding the distribution of the AYD at the end of its progradation stage, which provides fundamental information for analyzing subsequent erosion processes since 1855 AD. This study differs from existing studies on the AYD, which are all based on geological approaches. It provides insight into the evolution of the AYD through an alternative means, viz. a process-based morphodynamic-modeling approach.Coastal Engineerin

Use pressure data below seat cushions to evaluate comfort

During a flight, passengers spend most of their time sitting in their seats. Studying the comfort and discomfort while passengers are sitting is helpful to improve the overall comfort during a flight. Pressure mats are commonly used in studies to collect pressure distribution in order to research sitting comfort. Different from most past studies, in which pressure mats are placed on the top of the cushions, the focus of this paper is to show the potential of placing pressure mat below the seat cushion. Three identical cushions differing in stiffness were prepared. The pressure distribution of 12 sitting postures was collected from 33 subjects both at the top as well as at the bottom of the foam in a randomized order. After sitting on each cushion, the participant was asked to leave the seat and complete a sitting comfort and discomfort questionnaire. The results show that the softest cushion got the highest rank in short-term comfort and lowest rank in short-term discomfort. The recorded pressure distributions both on the top and at the bottom of the foam can influence comfort and discomfort. This indicates the potential to use pressure distributions under the foam to evaluate the perceived comfort and discomfort in sitting, which might reduce the intrusive feeling of theparticipants in comfort studies.Mechatronic DesignMaterials and Manufacturin