Numerical and experimental analysis of the thermoforming process parameters of semi-spherical glass fibre thermoplastic parts

Abstract The thermoforming process is considered among the most promising manufacturing processes for delivering both high quality and volume of thermoplastic composite parts as it exploits all the principal advantages these materials provide. Nevertheless, a series of critical defects may be introduced during the process such as wrinkles, shear deformation of the textile, variation on the thickness as well as geometric distortions and residual stresses which are highly dependent on the material characteristics and the parameters of the process itself. In the present work presented is an analysis of these parameters and their influence on a simple semi-spherical geometry using finite element modelling. The results are also compared with actual experimental results

On the Predictive Tools for Assessing the Effect of Manufacturing Defects on the Mechanical Properties of Composite Materials

Abstract Despite the recent advances in the field of manufacturing of composite materials, with both thermosetting and thermoplastic matrix, the presence of irregularities that influence their mechanical properties and behavior remains a critical issue to the industry. The defects with the form of porosity, fiber misalignment, delamination and poor consolidation are considered an unavoidable form of initial damage to composite materials. The reduction of the defects by optimizing the manufacturing process and the creation effective tools for predicting the residual properties of these materials during the design and/or the manufacturing phase are of great interest. In the present work, presented are these numerical tools and methodologies based either on the idea of optimizing the manufacturing process or by using data derived from non-destructive tests. Finally, the possibility of combining the two approaches is being proposed

notes on the hybrid urans les turbulence modeling for internal combustion engines simulation

Abstract In the past 20 years, Large Eddy Simulation methods have continuously increased their popularity among the Internal Combustion Engines modeling community, due to their intrinsic potential in the description of the unsteady and randomly generated in-cylinder flow structures. Such capability has gained further relevance in the simulation of modern turbocharged GDI engines, where the high-fidelity resolution of cycle-to-cycle variability phenomena is crucial for the evaluation of the engine performance and emission trends. Nonetheless, even after many years of development the application of standard LES methods to full-scale engine geometries is still not straightforward, due to: the need for specific, turbulence-generating boundary conditions at open ends; more severe grid resolution/quality and time step requirements compared to unsteady RANS; the need for high-order (at least second-order accurate) numerical schemes. Therefore, a viable alternative might be found in hybrid URANS/LES turbulence modeling, which has the potential to achieve adequate scale-resolving levels wherever actually needed, but mitigating at the same time some of the aforementioned concerns. In the present work we discuss the current status and perspectives of URANS/LES hybrids in the ICE field, based on the scientific literature state-of-the art and on a series of previous computational studies made by the authors. Outcomes from this study essentially confirm that this class of methods deserve further attention and will likely support URANS and standard LES in the near future as an effective computational tool for the ICE development and optimization

Assessment of a Hydrogen-Fueled Heavy-Duty Yard Truck for Roll-On and Roll-Off Port Operations

The port-logistic industry has a significant impact on the urban environment nearby ports and on the surrounding coastal areas. This is due to the use of large auxiliary power systems on ships operating during port stays, as well as to the employment of a number of fossil fuel powered road vehicles required for port operations. The environmental impact related to the use of these vehicles is twofold: on one hand, they contribute directly to port emissions by fuel consumption; on the other hand, they require some of the ship auxiliary systems to operate intensively, such as the ventilation system, which must operate to remove the pollutants produced by the vehicle engines inside the ship. The pathway to achieve decarbonization and mitigation of energy use in ports involves therefore the adoption of alternative and cleaner technology solutions for the propulsion systems of such port vehicles. This paper presents the performance analysis of a hydrogen powered cargo-handling vehicle for roll-on and roll-off port operations in a real case scenario. The fuel cell/battery hybrid powertrain of the vehicle has been previously designed by the authors. On the base of real data acquired during an on-field measurement campaign, and by means of a validated numerical model of the vehicle dynamics, different mission profiles are defined, in terms of driving and duty cycles, in order to represent typical port operations. A rule-based energy management strategy is then used to estimate the energy and hydrogen consumptions required by the vehicle and to assess its suitability to accomplish the defined target port operations. Outputs from this study show the potential of the proposed solution to take the place, in a foreseeable future, of conventional Diesel-engine vehicles, today commonly used in port logistics, towards a zero-emission scenario

Preliminary design of a fuel cell/battery hybrid powertrain for a heavy-duty yard truck for port logistics

Abstract The maritime transport and the port-logistic industry are key drivers of economic growth, although, they represent major contributors to climate change. In particular, maritime port facilities are typically located near cities or residential areas, thus having a significant direct environmental impact, in terms of air and water quality, as well as noise. The majority of the pollutant emissions in ports comes from cargo ships, and from all the related ports activities carried out by road vehicles. Therefore, a progressive reduction of the use of fossil fuels as a primary energy source for these vehicles and the promotion of cleaner powertrain alternatives is in order. The present study deals with the design of a new propulsion system for a heavy-duty vehicle for port applications. Specifically, this work aims at laying the foundations for the development of a benchmark industrial cargo–handling hydrogen-fueled vehicle to be used in real port operations. To this purpose, an on-field measurement campaign has been conducted to analyze the duty cycle of a commercial Diesel-engine yard truck currently used for terminal ports operations. The vehicle dynamics has been numerically modeled and validated against the acquired data, and the energy and power requirements for a plug-in fuel cell/battery hybrid powertrain replacing the Diesel powertrain on the same vehicle have been evaluated. Finally, a preliminary design of the new powertrain and a rule-based energy management strategy have been proposed, and the electric energy and hydrogen consumptions required to achieve the target driving range for roll-on and roll-off operations have been estimated. The results are promising, showing that the hybrid electric vehicle is capable of achieving excellent energy performances, by means of an efficient use of the fuel cell. An overall amount of roughly 12 kg of hydrogen is estimated to be required to accomplish the most demanding port operation, and meet the target of 6 h of continuous operation. Also, the vehicle powertrain ensures an adequate all-electric range, which is between approximately 1 and 2 h depending on the specific port operation. Potentially, the hydrogen-fueled yard truck is expected to lead to several benefits, such as local zero emissions, powertrain noise elimination, reduction of the vehicle maintenance costs, improving of the energy management, and increasing of operational efficiency

Effects of two plant oil-based products on the mortality of red palm weevil and morpho-physiological characteristics of palm

The red palm weevil (RPW), Rhynchophorous ferrugineus Oliver (Coleoptera: Curculionidae), is an economically important, tissue-boring pest of date palm in many parts of the world. The aim of the work was to investigate the effects of two plant oil-based products (BRK6 and BRK9) on the mortality of RPW (Exp. 1) and morpho-physiological characteristics of palm (Exp. 2). Laboratory experiments showed that the two mixture of oils BRK6 and BRK9 showed larvicide and adulticide properties. These properties were more pronounced on BRK9 than BRK6. The lethal concentration for 50% of individuals (LC50) calculated by probit, of BRK6 was 0.22% (for the 90% of individuals LC90 = 0.34) while for BRK9 the calculated LC50 was 0.10% (LC90 = 0.66). These data show that a smaller amount of BRK9 oil was required to induce the 50% of mortality of RPW larvae. As regards to the adults, BRK9 and BRK6 were effective only at the highest concentration (2 and 5%, respectively). Finally, injection of BRK9 into the palm trunk showed to promote chlorophyll content and photosynthesis of leaves thanks to a good translocation of zinc

Hyperthermic intraperitoneal chemotherapy in interval debulking surgery for advanced epithelial ovarian cancer: A single-center, real-life experience.

Background: An improvement in survival without increasing perioperative morbidity in patients with advanced epithelial ovarian cancer treated with hyperthermic intraperitoneal chemotherapy (HIPEC) after interval debulking surgery (IDS) has been recently demonstrated in a randomized controlled trial. This study was aimed at assessing the feasibility and perioperative outcomes of the use of HIPEC after IDS at a referral cancer center. Methods: Over the study period, 149 IDSs were performed. Patients who had at least International Federation of Gynecology and Obstetrics stage III disease, with <2.5 mm of residual disease (RD) at the end of surgery and were not participating in clinical trials received HIPEC. Moreover, specific exclusion criteria were considered. These patients were compared with 51 patients with similar clinical characteristics at the same institution and within the same timeframe who did not receive HIPEC. Results: No differences in patient or disease characteristics with the exception of the type of neoadjuvant chemotherapy (P =.002) were found between the 2 groups. As for surgical characteristics, significant differences were found in RD after IDS (P =.007) and in the duration of surgery (P <.001), whereas the bowel resection and diversion rates (P =.583 and P =.213, respectively) and the postoperative intensive care unit and hospital stays (P =.567 and P =.727, respectively) were comparable. The times to start adjuvant chemotherapy were also similar (P =.998). Equally, the rates of any grade of both intraoperative complications (P =.189) and early postoperative complications (P =.238) were superimposable. Conclusions: In the authors' experience, the addition of HIPEC to IDS is feasible in 35% for the population. This value might increase with changes in the inclusion/exclusion criteria. HIPEC does not increase perioperative complications and does not affect a patient's recovery or time to start adjuvant chemotherapy. HIPEC should be offered to select patients listed for IDS

Uncertainty assessment for measurement and simulation in selective laser melting: a case study of an aerospace part

In this work, the additive manufacturing process selective laser melting is analysed with the aim of realising a complex piece for aerospace applications. In particular, the effect of the manufacturing process and of the following thermal treatments on the dimensions of the workpiece is evaluated. The study is based on a hybrid approach including a simulation of the whole manufacturing process by advanced software packages and the dimensional measurements of the realised pieces taken by a coordinate measuring machine (CMM). The integrated use of simulation and measurements is carried out with the aim of validating the simulation results and of identifying the operational limits of both approaches; this analysis is based on metrological evaluation of the results of both the simulation and the tests, taking into account the uncertainty of the data. In addition, the main causes of uncertainty for the simulation activity and the experimental data have been identified, and the effects of some of them have also been experimentally evaluated. Based on the experimental validation, the simulation seems to predict the absolute displacement of the supports of the piece in a satisfactory way, while it is unable, in the actual configuration, to assess the conformity of the surface to its very tight shape tolerances. Conformity assessment of the surface should be carried out by CMM measurement. Integrated use of simulation and experimental results is expected to strongly improve the accuracy of simulation results for the effective and accurate design and control of the additive manufacturing process, including dimensional control and thermal treatments to mitigate induced thermal stresses.</p

Prevalence and severity of airway obstruction in an Italian adult population

Background. This study sets out to estimate the prevalence and the degree of severity of bronchial obstruction in an adult population with three different diagnostic criteria: the European Respiratory Society (ERS), the American Thoracic Society (ATS), and the World Health Organization (WHO) defined as Global Obstructive Lung Disease (GOLD). Methods. 1514 subjects underwent complete medical evaluation and spirometry. Results. The prevalence of bronchial obstruction was respectively 27.5% (ERS), 33% (GOLD), and 47.3% (ATS). The prevalence of bronchial obstruction in the smoker group was 33.4% (ERS), 38.1% (GOLD), and 52.3% (ATS). The prevalence of obstruction in the ex-smoker group was 33% (ERS), 41.4% (GOLD), and 57.1% (ATS). The prevalence of obstruction in the non-smoker group was 21.1% (ERS), 24.9% (GOLD), and 38.6% (ATS). Conclusions. The results show that the prevalence of airway obstruction increases proportionally with age; the cigarette smoking represents an important conditioning factor. These observations warrant the necessity of a more complete and multi-parametric analysis in the evaluation of patients with airway obstruction using methodologies that explore the functional state and the risk factors that cause the airway obstruction

Prevalence and severity of airway obstruction in an Italian adult population

Background. This study sets out to estimate the prevalence and the degree of severity of bronchial obstruction in an adult population with three different diagnostic criteria: the European Respiratory Society (ERS), the American Thoracic Society (ATS), and the World Health Organization (WHO) defined as Global Obstructive Lung Disease (GOLD). Methods. 1514 subjects underwent complete medical evaluation and spirometry. Results. The prevalence of bronchial obstruction was respectively 27.5% (ERS), 33% (GOLD), and 47.3% (ATS). The prevalence of bronchial obstruction in the smoker group was 33.4% (ERS), 38.1% (GOLD), and 52.3% (ATS). The prevalence of obstruction in the ex-smoker group was 33% (ERS), 41.4% (GOLD), and 57.1% (ATS). The prevalence of obstruction in the non-smoker group was 21.1% (ERS), 24.9% (GOLD), and 38.6% (ATS). Conclusions. The results show that the prevalence of airway obstruction increases proportionally with age; the cigarette smoking represents an important conditioning factor. These observations warrant the necessity of a more complete and multi-parametric analysis in the evaluation of patients with airway obstruction using methodologies that explore the functional state and the risk factors that cause the airway obstruction