Front Pattern Research Articles

P6146Atmospheric front patterns and acute cardiovascular diseases, a new perspective in the cardiovascular threat of global climate change

Abstract Background There is substantial evidence that the health threat of global climate change is real and it could be a medical emergency. The impact of climate change on health is mediated through atmospheric parameters which are direct environmental stressors on the human body and have a potential cardiovascular (CV) morbidity and mortality effect. Acute cardiovascular diseases (ACVDs) are already major public health issues and in the future unfavourable atmospheric situations, such as increasingly volatile fronts and their negative effects can further increase this problem. Despite evidence about the importance of different atmospheric parameters on health outcomes, there have been few results for atmospheric front patterns' CV effects. Weather fronts are the most complex atmospheric phenomena therefore these atmospheric parameters might have the greatest influence on ACVDs. Purpose We aimed to explore the effects of atmospheric front patterns on ACVDs. Methods A time series Poisson-regression analysis was used to analyse 6499 ACVD hospital admissions, during a five-year period (2009–2013), in light of front patterns. Covariates were three-day (target day and the two previous days) front sequence patterns comprised of the five major front types (no front, warm front, occluded front, cold front, stationary front). Relative risk (RR) estimates for front effects were adjusted for seasonality. The relationship on all ACVDs combined and separately on patient groups by major CV risk factors (hypertension, hyperlipidaemia, diabetes, previous CV diseases) was examined. Results We found that in general, front patterns containing warm front days had a detrimental effect. A warm front, when followed by two days with no fronts present, increased RR by 46% (CI: 4–89%, p=0,015). Cold fronts however were protective. A no front – cold front – occluded front pattern corresponded to a 28% (CI: 8–49%, p=0,037) decrease in RR, with this pattern being present in 1.1% of all days of the study period. Out of the group specific results an occluded front, following days with no fronts present, showed to have the largest effect on hyperlipidaemic patients, increasing RR by 144% (CI: 51–295%, p<0.001). Conclusions This work provides both independent evidence of front patterns' CV effects and a novel tool to investigate and help the understanding of complex associations between atmospheric fronts and ACVDs. The importance of our findings is growing in the context that extreme atmospheric conditions and changes are likely to become more common in the future as a result of climate change. Medical meteorology may open up a new horizon and become an important field of preventive cardiology in the future. In conclusion, a better understanding of atmospheric front effects is of particular importance in order to help identify possible targets for future prevention strategies.

Visualization Tests on Variation of Scour Front under a Pipeline in Steady Currents

The intersection of the span shoulder and the scour hole under a pipeline, also called the scour front, can affect the scour hole extension rate and the bearing capacity of the span shoulder, which is associated with pipeline spanning and failure. Studies on scour front evolution are limited due to technical restrictions. In this study, visualization experiments on three-dimensional scour under a pipeline in steady currents were performed to reveal the evolution of the scour front at the beginning of scour process, and the parametric effects on the scour front pattern. The angle of scour front witnessed a steady drop at the start of the scour development process and fluctuated gently thereafter. This can be attributed to the decrease in the blockage effect over time. A gravitational movement was observed on the downstream end of the scour front, which is associated with the variation of fluid pressure along the scour front. The scour front pattern was described by the angle between the scour front and the streamwise direction. Parametric analysis showed that the averaged scour front angle climbs as the Froude number increases and the pipeline embedment drops. This phenomenon can be expounded by the intensified flow deflection near the span shoulder due to the enhancement of the pipeline blockage effect, caused by the ascending Froude number and descending pipeline embedment. The results of this study can be adopted in future mechanism investigations on the scour hole propagation rate and the failure analysis on the span shoulder.

Can pattern and depth of invasion predict lymph node relapse and prognosis in tongue squamous cell carcinoma

BackgroundTongue squamous cell carcinoma (TSCC) is a special type of oral cancer. Cervical lymph node relapse may occur in a large percentage of TSCC patients, which usually indicates poor prognosis. In this cohort study, we focused on the predictive value of the pathological features on cervical lymph node relapse and TSCC prognosis (disease free survival).MethodsOne hundred forty-one TSCC patients staged as T1–2N0 were enrolled and categorized. Subjects were followed-up for 60 months. Univariate analysis was performed with Chi-square test for cervical lymph node relapse and Kaplan-Meier survival analysis and log rank P value for patient prognosis; multivariate analysis was also utilized with Cox regression.ResultsIn univariate analysis, trabes growth pattern, depth of invasion greater than 4 mm, poor pathological differentiation and neurovascular invasion were considered as risk factors for cervical lymph node relapse and poor prognosis. In multivariate analysis, only patients with trabes growth pattern in the invasive front or depth of invasion larger than 4 mm had a higher risk of metastasis. Elder age group and trabes growth pattern of invasive front were considered as predictors of poor prognosis. Bad habits of smoking and alcohol consumption were related to the higher risk of metastasis.ConclusionTrabes growth pattern of invasive front was a potent risk factor for TSCC cervical lymph node relapse and indicated poor prognosis. Preventive therapy including selective neck dissection was thus suggested for certain patients.Trial registration Not applicable.

Failure analysis of a crankshaft of a helicopter engine

A detailed analysis of a crankshaft failure belonging to a helicopter engine is presented. The main objective of this work was to analyze the characteristics of the failure and determine the root cause of the failure of the crankshaft. In order to determine the causes of the crankshaft failure, a material analysis was performed, followed by a detailed observation of the failure mechanisms through macroscopic, microscopic and microstructural examinations of the fracture surface. A preliminary observation of the fractured crankshaft indicates that this failure occurred by a fatigue process where the fracture surface shows obvious signs of cyclic propagation mechanisms. The existence of a large number of beachmarks indicates significant crack growth characterized by the effect of successive starts and stops of the engine by the operating conditions. These beachmarks cover about two-thirds of the total area of the fracture surface and the uniform geometric pattern of the crack front, along the entire propagation zone, allows to conclude that the fatigue process occurred from a loading state consisting essentially of cyclic bending stresses between the crankweb and the main journal of the crankshaft. No original defect was observed either on the surface or inside the material that could be the source of the crack initiation and growth and subsequent final fracture of the component. The analysis of the shell bearings applied to the main journal revealed a significant damage, with fractured location lugs, that are believed to be at the origin of the crack initiation of the crankshaft.

Double fronts in the Yellow Sea in summertime identified using sea surface temperature data of multi-scale ultra-high resolution analysis

Fronts are ubiquitous phenomena in oceans, and they play a significant role in marine hydrodynamics and ecology. During the stratified season of a shelf sea, the coastal front is usually considered as a single front, i.e., the tidal mixing front. However, using high resolution (~1 km) Multi-scale Ultra-high Resolution (MUR) analysis sea surface temperature (SST) data, this study observes persistent double fronts along the Yellow Sea coast in summertime. The double fronts comprise the well-known offshore tidal mixing front and a nearshore front, and the nearshore front has not been previously reported. The climatological (2002–2017) monthly mean result shows that the double fronts with two SST gradient peaks exceeding ~2 °C/100 km and opposite SST gradient directions basically remain unchanged from June to August, whereas the frontal spacing decreases in September. Analyses based on a two-layer concept model suggest that a topographic slope along with tidal mixing could induce the pattern of double fronts. The frontogenesis of nearshore thermal front could be associated with the different responses of the water column of different water depths to insolation. The offshore movement of the nearshore front in September could be related to the fast cooling of nearshore water and intensified offshore wind, and the topographic slope is important for determining the pattern of double fronts (loose or tight). This study shows a new pattern of coastal fronts in the stratified season, and indicates the significance of high resolution satellite data. The discovery of the double front pattern implies the influence of coastal fronts during the stratified season on marine ecology and environment in a shelf sea might be underestimated.

Assessment of Heat Transfer Characteristics of a Latent Heat Thermal Energy Storage System: Multi Tube Design

In this study, a numerical investigation of heat and mass transfer characteristics of a high temperature phase change material (PCM) is presented. The phase change material used is Sodium Nitrate with a melting point of 306 °C. For a fixed PCM mass, investigations are carried out on a multi-tube heat exchanger system for examining the effects of tube size and number of tubes on overall heat transfer rate. The performance of latent heat storage system during the charging and discharging processes are discussed. Further, the results are elaborated for three multi-tube systems to optimize the number of tubes to be used with the constant heat transfer surface area. The natural convection pattern during charging is observed with the help of temperature contours and streamlines. The solidification front pattern of the PCM, during the discharging process is visualized through melt fraction contours. With the increase in the number of tubes from 13 to 25, the heat distribution throughout the storage system is very effective which lead to reduction in charging and discharging times by 20% and 48% respectively.

The effect of front pattern perforation shape on thermal sensations of occupants in personalized ventilation systems

The aim of this study was to find the most favourable shape of the front panel perforation shape, which would allow us to obtain the greatest cooling effect and – at the same time – be positively perceived by the people. The capacity of the personalized ventilation (PV) system to affect human thermal sensation, with different shapes of front panel perforation used, was analyzed.Once the pilot study was conducted, it used a rectangular nozzle of front pattern size 320 mm × 125 mm and six different front patterns perforation shapes with round holes were tested. Operational parameters such as: airflow 20 l/s, supply air temperature at 24 °C or ambient temperature at 28 °C were invariable. The experiment consisted of a two-stage analysis of air jets characteristics and of tests in which people participated. Twenty-five male volunteers, at the age of 22–23 were engaged. They their assessed thermal sensation and completed relevant questionnaires.On the basis of the results of the above study, differences in jet characteristics depending on the pattern shapes and their different impact on thermal sensation of the volunteers were demonstrated. The biggest cooling effect was obtained using front panels with small hole size (d = 5 mm). These perforations allowed us to obtain a more even air outflow from the entire panel. This ensured a broader airflow of lower velocity, reaching and affecting a larger area. With holes of larger size (d = 15 mm), air outflow occurred mainly through the central part, which produced narrow jets of higher velocity.

Prediction of the vacuum assisted resin transfer molding (VARTM) process considering the directional permeability of sheared woven fabric

In this study, the in-plane permeability of a woven composite was characterized with respect to the fiber orientation of the deformed woven fabric, to predict the vacuum assisted resin transfer molding (VARTM) process. An analytical model was suggested to predict the permeability of shear-deformed woven fabric and the model was compared to the experiment results. Based on the developed model, the VARTM process for the U-shaped composite structure was simulated using commercial software (Pam-Form and Pam-RTM). The simulation results were compared with that of the VARTM experiment. Considering the fiber directional permeability of the shear-deformed woven fabric, it was concluded that the VARTM simulation could accurately predict the VARTM process results such as the filling time and flow front pattern.

Data Set for the Reporting of Oral Cavity Carcinomas: Explanations and Recommendations of the Guidelines From the International Collaboration of Cancer Reporting.

The International Collaboration on Cancer Reporting is a nonprofit organization whose goal is to develop evidence-based, internationally agreed-upon standardized data sets for each cancer site for use throughout the world. Providing global standardization of pathology tumor classification, staging, and other reporting elements will lead to the objective of improved patient management and enhanced epidemiologic research. Carcinomas of the oral cavity continue to represent a significant oncologic management burden, especially as changes in alcohol and tobacco use on a global scale contribute to tumor development. Separation of oral cavity carcinomas from oropharyngeal tumors is also important, as management and outcome are quite different when human papillomavirus association is taken into consideration. Topics such as tumor thickness versus depth of invasion, pattern of invasive front, extent and size of perineural invasion, and margin assessment all contribute to accurate classification and staging of tumors. This review focuses on the data set developed for Carcinomas of the Oral Cavity Histopathology Reporting Guide, with discussion of the key elements developed for inclusion.

The Effect of Curvature and Confinement on Gas-Phase Detonation Cellular Stability

We examine the evolution of cellular detonation patterns in a two-dimensional channel with yielding confinement on one side. It is shown that in a narrow channel of fixed width the number of cells first increase with decreasing level of confinement. Subsequently, with increasingly weaker confinement, the cells then grow in size and the total number of cells in the channel decreases. For sufficiently weak confinement, the flow becomes laminar with no detonation cells. We examine the relative importance of two fluid mechanisms underlying the observed evolution: global curvature of the detonation shock front due to induced flow divergence caused by the yielding confinement, and energy loss associated with transverse shock wave transmission to the confining material. In order to determine which effect is dominant, we compare two types of numerical calculations. One involves specialized calculations in which the explosive boundary, along which impermeable flow conditions are applied, is deflected through a range of specified angles upon detonation arrival. This set-up mimics the effect of yielding confinement in terms of induced flow divergence, but removes the transverse wave energy loss that would otherwise occur due to wave transmission into the confiner material. The second involves multi-material simulations which can account for transverse wave energy loss into the confining material. Shock polar theory is used to select confiner densities in the multi-material calculations that provide equivalent material interface deflection angles at the detonation shock to the angles imposed in the deflected solid wall calculations. We determine that the induced global curvature of the wave primarily drives both the evolution of the cellular pattern and eventual stabilization of the detonation front, characterized by laminar flow solutions. In wider channels, we show that the detonation front will likely remain unstable even for very weak confinement, as the mean curvature of the front only becomes significant near the edge of the explosive domain.

Variability of orogenic magmatism during Mediterranean-style continental collisions: A numerical modelling approach

The relationship between magma generation and the tectonic evolution of orogens during subduction and subsequent collision requires self-consistent numerical modelling approaches predicting volumes and compositions of the produced magmatic rocks. Here, we use a 2D magmatic-thermomechanical numerical modelling procedure to analyse rapid subduction of a narrow ocean, followed by Mediterranean style collision, which is characterized by the gradual accretion of lower plate material and slab migration towards the orogenic foreland. Our results suggest that magmatism has a large-scale geodynamic effect by focusing deformation throughout the entire subduction and collision process. The rheological structure and compositional layering of the crust impose a key control on the distribution of magmatic rocks within the orogen. Compared to previous simplified homogeneous crustal models, a compositionally layered crust causes an increase in felsic material influx during continental collision and results in shallower magmatic sources that migrate with time towards the foreland. Changes in the deformation style may be locally driven by magma emplacement rather than by slab movement. Our modelling also demonstrates that the migration pattern of the deformation front and the magmatic arc relative to the location of the suture zone may be driven by lower crustal indentation in the overriding plate during early stages of collision. The modelling predicts a gradual change in magma source composition with time from typical calc-alkaline to ones associated with relamination and eduction during subduction, collision and slab detachment. This transition explains the compositional changes of magma their temporal and spatial migration, as well as the observed link with deformation in the Dinarides orogen of Central Europe selected as a case study.

Period steady-state identification for a nonlinear front evolution equation using genetic algorithms

In molecular beam epitaxy, it is known that a planar surface may suffer from a morphological instability in favour to different front pattern formations. In this context, many studies turned their focus to the theoretical and numerical analysis of highly nonlinear partial differential equations which exhibit different scenarios ranging from spatio-temporal chaos to coarsening processes (i.e., an emerging pattern whose typical length scale with time). In this work our attention is addressed toward the study of a highly nonlinear front evolution equation proposed by Csahok et al. (1999) where the unknowns are the periodic steady states which play a major role in investigating the coarsening dynamics. Therefore the classical methods of Newton or a fixed point type are not suitable in this situation. To overcome this problem, we develop in this paper a new approach based on heuristic methods such as genetic algorithms in order to compute the unknowns.

Dynamic Rupture Modeling of the M7.2 2010 El Mayor‐Cucapah Earthquake: Comparison With a Geodetic Model

AbstractThe 2010 Mw 7.2 El Mayor‐Cucapah earthquake is the largest event recorded in the broader Southern California‐Baja California region in the last 18 years. Here we try to analyze primary features of this type of event by using dynamic rupture simulations based on a multifault interface and later compare our results with space geodetic models. Our results show that starting from homogeneous prestress conditions, slip heterogeneity can be achieved as a result of variable dip angle along strike and the modulation imposed by step over segments. We also considered effects from a topographic free surface and find that although this does not produce significant first‐order effects for this earthquake, even a low topographic dome such as the Cucapah range can affect the rupture front pattern and fault slip rate. Finally, we inverted available interferometric synthetic aperture radar data, using the same geometry as the dynamic rupture model, and retrieved the space geodetic slip distribution that serves to constrain the dynamic rupture models. The one to one comparison of the final fault slip pattern generated with dynamic rupture models and the space geodetic inversion show good agreement. Our results lead us to the following conclusion: in a possible multifault rupture scenario, and if we have first‐order geometry constraints, dynamic rupture models can be very efficient in predicting large‐scale slip heterogeneities that are important for the correct assessment of seismic hazard and the magnitude of future events. Our work contributes to understanding the complex nature of multifault systems.

Satellite observation of the winter variation of sea surface temperature fronts in relation to the spatial distribution of ichthyoplankton in the continental shelf of the southern East China Sea

ABSTRACTThe wintertime variations and distributions of sea surface temperature (SST) and thermal fronts associated with the spatial distribution of ichthyoplankton were investigated in the continental shelf waters of the southern East China Sea (ECS) by using 10 year (2005–2015) satellite SST images with an entropy-based edge detection method. The Mainland China Coastal Front and Kuroshio Front (KF) in winter (December to March) were examined with SST gradient magnitudes (GMs) of 0.20–0.40 and 0.30–0.45°C Km−1, respectively, along the 50 m and 100–200 m isobaths in the southern ECS. These two fronts coincided with isotherms of 14–16°C and 21–22°C, respectively. The Mainland China Coastal Front pattern remained fairly stable along the 50 m isobaths, and the coexisting SST front and upwelling were shifted seaward or shoreward with the recession or intrusion of the KF during the winters. Notably, the SST GMs of the KF showed a significant strengthening that was higher than those of the past two decades. Moreover, the total abundance of the nearshore waters of the KF (which was occupied by approximately 75% neritic species) was 23 times higher than that of the offshore waters (which was occupied by approximately 63.60% oceanic species). We suggest that the generation of the KF in winter may act as the biological barrier of oceanic organisms and larval fishes in the study area.

The role of the front pattern shape in modelling personalized airflow and its capacity to affect human thermal comfort

The aim of the tests was to demonstrate the influence of the front pattern shape and its effect on human thermal sensations. Both the cooling capacity in summer conditions and the heating capacity in winter conditions were considered. Eight different types of the front pattern were tested at constant working parameters such as airflow (20 l/s), temperature of supply air (24 °C – summer conditions, 22 °C – winter conditions) and ambient temperature (28 °C – summer conditions, 18 °C – winter conditions). In order to determine the thermal sensation, a thermal manikin was used and equivalent temperature value teq was applied. On the basis of test results, differences in airflow characteristics were demonstrated and its varied influence on thermal sensation. The patterns with round apertures had greater cooling capacity as compared to the other shapes(cross-, rectangle- or star-shaped apertures). Among the round apertures, better values were achieved by those with higher diameters. The most advantageous patterns tested were those with round apertures of 15 mm diameter and 30–50% perforation ratio. These allowed for high cooling effect in summer conditions and considerable teq increase in winter conditions, as compared to that without PV. Operating PV brought about changes in the results teq at the level of 25–30% in summer and 60–75% in winter, as compared to the values obtained without PV, which additionally justifies the rationale behind application of PV.

Mechanisms leading to the frequent occurrences of hypoxia and a preliminary analysis of the associated acidification off the Changjiang estuary in summer

Based on literature data and shipboard observations, this study investigated the main environmental characteristics of the seafloor topography, current field, front, and upwelling that are closely related to hypoxia occurrence off the Changjiang estuary. The physical processes of the plume front and upwelling off the Changjiang estuary in summer were coupled. The vertical distribution pattern of the plume front was closely related to the upwelling. By reviewing and analyzing the historical summer hypoxia events off the Changjiang estuary, we statistically demonstrated the spatial structure of the horizontal distribution of the hypoxic zone and investigated the location of occurrence zone of the hypoxia. We found that the dissolved oxygen (DO) concentration on the inner continental shelf off the estuary showed a “V” shape in relation to station depth. Therefore, we noted that the hypoxic water on the inner continental shelf mostly occurred on the slopes with steep seafloor topography. Base on the current understanding of the hypoxic mechanisms off the Changjiang estuary, we analyzed the biogeochemical mechanisms that could cause the steep terrain off the Changjiang estuary to become the main areas prone to summer hypoxia and explained the internal relations between the location of the hypoxic zone on the slopes and the plume front and upwelling. The plume front and upwelling off the Changjiang estuary and their coupling were important driving forces of summer hypoxia. The continuous supply of nutrients affected by the interaction of the plume front extension of the Changjiang Diluted Water (CDW) and upwelling and the favorable light conditions were important mechanisms causing the phytoplankton blooms and benthic hypoxia off the Changjiang estuary in summer. By analyzing oxygen utilization, organic carbon mineralization, and nutrient regeneration in the hypoxic zone, we observed that the significant oxygen utilization process off the Changjiang estuary in summer also mainly occurred near the steep slopes with front and upwelling features and confirmed the apparent nutrient loss in the benthic hypoxic zone. Meanwhile, our analysis revealed that the sediment resuspension in the benthic boundary layer in the mud areas off the Changjiang estuary could also affect the oxygen utilization and mineralization of organic carbon and nutrient recycling and regeneration. This study also demonstrated that the steep terrain off the Changjiang estuary was the main location for summer acidification, and the coupling between the plume front and upwelling on the steep slopes was an important physical driving force inducing summer benthic acidification. Finally, we discussed issues to address in future studies of the hypoxic zone and water acidification off the Changjiang estuary.

Microgravity experiments and numerical studies on ethanol/air spray flames

Spray flames are known to exhibit amazing features in comparison with single-phase flames. The weightless situation offers the conditions in which the spray characteristics can be well controlled before and during combustion. The article reports on a joint experimental/numerical work that concerns ethanol/air spray flames observed in a spherical chamber using the condensation technique of expansion cooling (based on the Wilson cloud chamber principle), under microgravity.We describe the experimental set-up and give details on the creation of a homogeneous and nearly monosized aerosol. Different optical diagnostics are employed successfully to measure the relevant parameters of two-phase combustion. A classical shadowgraphy system is used to track the flame speed propagation and allow us to observe the flame front instability. The complete characterization of the aerosol is performed with a laser diffraction particle size analyser by measuring the droplet diameter and the droplet density number, just before ignition. A laser tomography device allows us to measure the temporal evolution of the droplet displacement during flame propagation, as well as to identify the presence of droplets in the burnt gases. The numerical modelling is briefly recalled. In particular, spray-flame propagation is schematized by the combustion spread in a 2-D lattice of fuel droplets surrounded by an initial gaseous mixture of fuel vapour and air.In its spherical expansion, the spray flame presents a corrugated front pattern, while the equivalent single-phase flame does not. From a numerical point of view, the same phenomena of wrinkles are also observed in the simulations. The front pattern pointed out by the numerical approach is identified as of Darrieus–Landau (DL) type. The droplets are found to trigger the instability. Then, we quantitatively compare experimental data with numerical predictions on spray-flame speed. The experimental results show that the spray-flame speed is of the same order of magnitude as that of the single-phase premixed flame. On the other hand, the numerical results exhibit the role played by the droplet radius in spray-flame propagation, and retrieve the experiments only when the droplets are small enough and when the Darrieus–Landau instability is triggered. A final discussion is developed to interpret the various patterns experimentally observed for the spray-flame front.

Relaxin-2 expression in oral squamous cell carcinoma.

When advanced, oral squamous cell carcinoma (OSCC) may involve adjacent non-epithelial structures, and the prognosis is worse for bone invasion. Human relaxin-2 is a peptide hormone that has recently been associated with cancer. It can induce human osteoclast differentiation and activation, suggesting a role in tumor-driven osteolysis. This study was a preliminary assessment of the prognostic role of relaxin-2 in surgical specimens of OSCC tissue and adjacent but uninvolved mandibular/maxillary bone. Relaxin-2 immunohistochemical expression and reaction intensity were assessed in tumor and uninvolved adjacent mandibular/maxillary bone specimens from 23 operated OSCC patients. All OSCC specimens were positive for relaxin-2. The intensity of its reaction in OSCC correlated significantly with the pattern of the tumor's invasion front (p = 0.02), being higher with the infiltrative pattern. Mean relaxin-2 immunohistochemical expression was higher in patients whose OSCC recurred after treatment than those experiencing no recurrence (81.3% ± 22.6% vs. 59.5% ± 29.7%, respectively). A significant direct association emerged between relaxin-2 expression in OSCC specimens and recurrence rate (p = 0.049). Relaxin-2 expression in OSCC should be further investigated as a potentially useful marker for identifying patients at higher risk of recurrence, who might benefit from closer follow-up and more aggressive adjuvant therapy. In other oncological settings, increasing evidence of relaxin being produced by cancer cells is prompting efforts to synthesize human relaxin-2 analogs capable of acting as antagonists and limiting tumor growth.

Optimization of Resin Infusion Processing for Composite Pipe Key-Part and K/T Type Joints Using Vacuum-Assisted Resin Transfer Molding

In present study, the optimization injection processes for manufacturing the composite pipe key-part and K/T type joints in vacuum-assisted resin transfer molding (VARTM) were determined by estimating the filling time and flow front shape of four kinds of injection methods. Validity of the determined process was proved with the results of a scaling-down composite pipe key-part containing of the carbon fiber four axial fabrics and a steel core with a complex surface. In addition, an expanded-size composite pipe part was also produced to further estimate the effective of the determined injection process. Moreover, the resin injection method for producing the K/T type joints via VARTM was also optimized with the simulation method, and then manufactured on a special integrated mould by the determined injection process. The flow front pattern and filling time of the experiments show good agreement with that from simulation. Cross-section images of the cured composite pipe and K/T type joints parts prove the validity of the optimized injection process, which verify the efficiency of simulation method in obtaining a suitable injection process of VARTM.

Industrial Screen-Printed n-Type Rear-Junction Solar Cells With 20.6% Efficiency

Screen-printed high-efficiency industrial n-type rear-junction silicon solar cells were fabricated on 5-in commercial grade Cz wafers. A furnace-diffused boron emitter and a laser-doped phosphorous front-surface field were applied to produce n-type rear-junction cells with PECVD SiN x on the front and PECVD AlO x /SiN x on the back for surface passivation. All contacts were screen printed. An average efficiency of 20.33% was achieved, while the best efficiency was 20.65%. The initial results indicate that the potential for a higher FF can be achieved by improving the front pattern and optimizing the condition for metallization, enabling an even higher efficiency.