Air gaps in protective clothing during flash fire exposure

Protective clothing is widely used in many industries and applications to provide protection against fire exposure. Exposure to fire can result in skin burn injuries that range from first-degree to third-degree burn injury depending on the exposure intensity and duration. Within the firefighting community, and especially the petroleum and petrochemical industries flash fire is one of the possible fire hazards for workers. Exposure to flash fire is usually of short duration (a few seconds) until the worker runs away from the fire location. The typical protective clothing system consists of a fire resistant fabric, the human skin, and an air gap between the fabric and skin. The protective performance of the clothing is evaluated based on the total energy transfer from the fabric to the skin through the air gap causing burn injury to the skin. Therefore the air gap between the protective clothing and skin plays an important role in determining the protection level provided by the clothing since the energy transfer through the air gap determines the amount of energy received by the skin. The more realistic the analysis of the air gap, the more reliable the evaluation of the protective performance of the clothing. This study introduces a more realistic analysis for the air gap between protective clothing and the skin compared to that found in the literature. More specifically, the study accounts for the combined conduction-radiation heat transfer through the air gap, which was treated as a thermal radiation participating medium with temperature dependent thermophysical properties. A finite volume model was developed to simulate the transient heat transfer in a single layer protective clothing system with radiation heat transfer. The model was employed to investigate the influence of the conduction-radiation heat transfer through the air gap on the overall heat transfer through the protective clothing system and hence on its protective performance. The influence of different protective clothing parameters on the combined conduction-radiation heat transfer through the air gap such as the air gap absorption coefficient, air gap width, fabric thickness, and fabric backside emissivity was studied. A comprehensive study of the influence of a periodic variation in the air gap width and associated inflow of cool air due to the motion of the person wearing the clothing on its protective performance was carried out. A wide range of variation in the frequency and amplitude of the fabric periodic movement was considered to capture different scenarios for the wearer’s motion. Finally, a finite volume model was developed to simulate the transient heat transfer in multiple layers firefighters’ protective clothing. The model considered the combined conduction-radiation heat transfer in the air gaps entrapped between the clothing layers, which were treated as thermal radiation participating media. The influence of each air gap on the overall performance of the clothing was investigated as well. The improved air gap model is a significant improvement for modeling heat transfer in protective clothing. It was used to obtain a more detailed knowledge of the theoretical performance of such clothing, e.g. it was found that reducing the fabric backside emissivity was more effective in improving the clothing protective performance than increasing the fabric thickness. It was also observed that the motion of the person wearing the clothing has a significant effect on the performance of the clothing: an increase in the frequency of the fabric movement improves the protection provided by the clothing, primarily due to the more frequent inflow of cool air, while an increase in the amplitude of the fabric movement reduces the protection provided by the clothing by concentrating the exposure on the skin. Finally, the air gaps entrapped between the clothing layers in firefighters’ protective clothing were found to improve the clothing performance, and the influence of the air gap between the moisture barrier and the thermal liner is greater than that of the air gap between the outer shell and the moisture barrier

Development of an additive manufacturing decision support system (AMDSS)

PhD ThesisAdditive manufacturing (AM) technology describes a set of processes capable of producing 3D physical products from CAD data directly. The rapid development of AM technologies and their wide applications makes the selection of the suitable process chains and materials a difficult task. Some researchers have tackled this problem by developing selectors that should assist users in their selections. The existing selector systems have some drawbacks: (і) often being outdated even before they were completely developed because new processes and materials are evolving continuously, (іі) representing only the point of view of their developers because users were not involved in the development process and (iii) not being holistic and able to help in all AM aspects for example process chains, materials, finishing methods and machines. This work has developed an updatable decision support system that assists users in their selections regarding AM process chains, materials, finishing methods, and machines. First, the study started by analyzing the available additive manufacturing selector systems and identifying their shortcomings. Secondly, the researcher identified target specifications for the new system, investigated different possible architectures for the system, selected knowledge based system (KBS) and database (DB) architecture to work together as a versatile tool that achieves the required target specifications. Next, the first version of the system was developed. Furthermore, verification and validation processes were made to test the developed system. Three case studies were used for the validation purpose: a typical consumer razor blade and two automotive components. These case studies were manufactured using AM technologies and then a comparison between real life decisions and the developed decision support system decisions were made. In addition, a number of interviews were performed in order to obtain users’ feedback about the first developed version. As a result of the feedback and evaluation a second version of the system was developed and evaluated. The results obtained from the second evaluation suggest that the second version is more effective than the first version during the selection process. To conclude, this study has shown that using KBS and DB together is effective to develop an updatable additive manufacturing decision support system. In addition, the user involvement in the development stage of the system enhances the system performance.The Arab Academy for Science & Technology & Maritime Transport

Faculty of Nursing, Kafrelsheikh University

Context: Health and well-being before marriage help to maintain the health of future children. Therefore, healthcare should begin before marriage through premarital care as it can recognize and modify health risk factors well-known to have adverse effects on pregnancy outcomes.Aim: The current research carried out to examine the effect of pre-marital care educational program on the knowledge and attitude of female university students. Methods: A quasi-experimental design (Pre-test/Post-test) was adopted to achieve the stated aim. A stratified sample of one thousand female students was recruited. The research was conducted at the Nursing and Commerce Faculties at Kafrelsheikh University, Egypt. Two tools were constructed by the researchers: A self-administered questionnaire and Pre-marital care attitude assessment scale.Results: The research findings revealed that 32.30% of nursing students have a high level of knowledge pre-program compared to 54.00% post-program, while 21.00% of commerce students have a high level of knowledge pre-program compared to 41.00% post-program. Moreover, there was a statistically significant difference between mean knowledge scores pre and post-program (p< 0.001). Concerning students’ attitudes, it was observed that positive attitudes expanded from 54.700% to 66.00 % among nursing students and from 49.00% to 57.500% among commerce students. As well, there was a statistically significant difference between pre-program and post-program attitude levels (p< 0.001). Conclusion: the research hypotheses were accepted as the knowledge and attitude of students were improved after receiving the program suggesting its effectiveness. The study recommended that university students should be equipped with adequate in-depth health information related to pre-marital care to expand the general population's mindfulness and impact their attitude toward pre-marital care

Does Surgical Resection of the Primary Tumor in Patients with Stage IV Breast Cancer Improve Survival?

Several lines of evidence suggest that it is time to re-examine the approach to the patient diagnosed with distant metastases at the initial breast cancer presentation.The aim of this study was to evaluate the impact of surgical therapy of the primary tumor and other clinical and staging factors on overall survival of patients with stage IV breast cancer. Patients and methods: This retrospective study included patients with stage IV breast cancer from 2000 to 2008. Patient's characteristics and survival distilled from medical files were evaluated using multivariate analysis.Results: Of 330 patients included in this study, 132 underwent surgery in the form of mastectomy. Local surgery of the primary tumor, lower TN staging, younger age, positive receptor status, lack of Her-2 amplification, bone –only metastasis and one site metastasis were associated with significantly higher survival while grade and pathological type were not. Median overall survival time for no surgery group was 15 months and 27 months for mastectomy group (P = 0.003).Three-year survival rate was higher for patients who did have surgery (34% vs 16%). Conclusion: Removal of the primary tumor in patients with primary distant metastatic breast cancer was associated with significantly higher survival. However, carefully designed prospective randomized trials are needed to confirm these results

Flexibility during the covid-19 pandemic response: Healthcare facility assessment tools for resilient evaluation

Healthcare facilities are facing huge challenges due to the outbreak of COVID-19. Around the world, national healthcare contingency plans have struggled to cope with the population health impact of COVID-19, with healthcare facilities and critical care systems buckling under the ex-traordinary pressures. COVID-19 has starkly highlighted the lack of reliable operational tools for assessing the level sof flexibility of a hospital building to support strategic and agile decision making. The aim of this study was to modify, improve and test an existing assessment tool for evaluating hospital facilities flexibility and resilience. We followed a five-step process for collecting data by (i) doing a literature review about flexibility principles and strategies, (ii) reviewing healthcare design guidelines, (iii) examining international healthcare facilities case studies, (iv) conducting a critical review and optimization of the existing tool, and (v) assessing the usability of the evaluation tool. The new version of the OFAT framework (Optimized Flexibility Assessment Tool) is composed of nine evaluation parameters and subdivided into measurable variables with scores ranging from 0 to 10. The pilot testing of case studies enabled the assessment and verification the OFAT validity and reliability in support of decision makers in addressing flexibility of hospital design and/or operations. Healthcare buildings need to be designed and built based on principles of flexibility to accommodate current healthcare operations, adapting to time-sensitive physical transformations and responding to contemporary and future public health emergencies

Flotation-separation of toxic metal ions from aqueous solutions using thiosemicarbazide derivatives as chelating agents and oleic acid as a surfactant

A simple and rapid procedure was developed for flotation-separation of toxic metal ions namely Hg2+, Mn2+ and Cd2+ from aqueous solutions. Thiosemicarbazide derivatives such as: 1-(amino-N-phenylmethanethio)-4-(pyridine-2-yl)thiosemicarbazide (H2PPS), N-phenyl-2-(pyridine-2-ylcarbamothioyl)hydrazinecarboxamide (H2PBO), 1-(amino(thioformyl)-N-phenylform)-4-(pyridine-2-yl)thiosemicarbazide (H2APO), and 1-(amino-N-(pyridine-3-yl) methanethio)-4-(pyridine-2-yl)thiosemicarbazide (H2PPY) have been used as organic chelating agents and oleic acid (HOL) as a surfactant. The different parameters affecting the flotation process namely, metal ion, ligands and surfactant concentrations, foreign ions (which are normally present in fresh and saline waters), pH and temperature are examined. About 100% of mercury, cadmium and manganese ions float at room temperature (~ 25 oC), at a metal:ligand ratio of 1:2  and at pH ~5. The procedure was successfully applied to recover Hg2+, Mn2+ and Cd2+ ions spiked into some water samples. The flotation mechanism is suggested based on some physical and chemical studies on the ligands and metal-complexes isolated from the floated layers

Response surface method for optimisation of SLA processing parameters

In the current study, response surface method (RSM) was applied to correlate stereolithography (SLA) process parameters such as layer thickness, hatch overcure, and part orientation to SLA part characteristics such as density, surface finish and ultimate tensile strength (UTS). The results showed that density was directly proportional to the hatch overcure but inversely affecting the layer thickness. Besides, the hatch overcure was shown to have a positive effect on the UTS, while the layer thickness was found to influence the UTS adversely. Furthermore, the relationship between the layer thickness and surface roughness was suggested to be directly proportional. The optimised values of process parameters indicated by the response surface model were 90°, 0.12 mm and 0.1 µm for the part orientation, hatch overcure and layer thickness, respectively. The corresponding predicted density, UTS and surface roughness of an SLA part were 1,098 kg/m3, 42.8 MPa and 5.31 µm, respectively

Selective Laser Melting for improving quality characteristics of a prism shaped topology injection mould tool insert for the automotive industry

Manufacturing process constraints and design complexities are the main challenges that face the aftermarket automotive industry. For that reason, recently, selective laser melting (SLM) is being recognised as a viable approach in the fabrication of injection moulding tool inserts. Due to its versatility, SLM technology is capable of producing freeform designs. For the first reported time, in this study SLM is recognized for its novel application in overcoming fabrication complexities for prism shaped topology of a vehicle headlamp’s reflector injection moulding tool insert. Henceforth, performance measures of the SLM-fabricated injection mould tool insert is assessed in comparison to a CNC-milled counterpart to improve quality characteristics. Tests executed and detailed in this paper are divided into two stages; the first stage assesses both fabricated tool inserts in terms of manufacturability; the second stage assesses the functionality of the end-products by measuring the surface roughness, dimensional accuracy and light reflectivity from the vehicle reflectors. The results obtained show that employing SLM technology can offer an effective and efficient alternative to subtractive manufacturing, successfully producing tool inserts with complex surface topology. Significant benefits in terms of surface roughness, dimensional accuracy and product functionality were achieved through the use of SLM technology. it was concluded that the SLM-fabricated inserts products proved to have relatively lower values of surface roughness in comparison to their CNC counterparts

Effect of Casting Conditions on the Fracture Strength of Al-5 Mg Alloy Castings

During the transient phase of filling a casting running system, surface turbulence can cause the entrainment of oxide films into the bulk liquid. Previous research has suggested that the entrained oxide film would have a deleterious effect on the reproducibility of the mechanical properties of Al cast alloys. In this work, the Weibull moduli for the ultimate tensile strength (UTS) and % elongation of sand cast bars produced under different casting conditions were compared as indicators of casting reliability which was expected to be a function of the oxide film content. The results showed that the use of a thin runner along with the use of filters can significantly eliminate the surface turbulence of the melt during mould filling which would lead to the avoidance of the generation and entrainment of surface oxide films and in turn produce castings with more reliable and reproducible mechanical properties compared to the castings produced using conventional running systems