3D TEXTILE PREFORMS AND COMPOSITES FOR AIRCRAFT STRCUTURES: A REVIEW

Over the last decades, the development of 3D textile composites has been driven the structures developed to overcome disadvantages of 2D laminates such as the needs of reducing fabrication cost, increasing through-thickness mechanical properties, and improving impact damage tolerance. 3D woven, stitched, knitted and braided preforms have been used as composites reinforcement for these types of composites. In this paper, advantages and disadvantages of each of them have been comprehensively discussed. The fabric architects and their specification in particular stitched preforms and their deformation mode for aerospace applications have been reviewed. Exact insight into various types of damage in textile preforms and composite that have the potential to adversely affect the performance of composite structure along with their inspection using NDT techniques have been elaborated. The research review reported in this paper can be very valuable to researchers to release the 3D composite behaviour under different loading conditions and also to get familiar with the manufacture of high quality textile composite for aircraft structures

Engineering Tunable Plasmonic Nanostructures To Enhance Upconversion Luminescence

Plasmonic nanostructures, which can confine and manipulate light below the diffraction limit, are becoming increasingly important in many areas of optical physics and devices. One of the areas that can greatly benefit from surface-plasmon mediated confinement of optical fields is the enhancement of emission in low quantum yield materials. The resonant wavelength for plasmonic structures used for emission enhancement is either the excitation or emission wavelengths of the luminescent material. Therefore, a key component in designing plasmonic structures used in luminescent enhancement applications is the ability to engineer and tune plasmonic building blocks to create structures resonant at the desired wavelength. In this thesis, we have used two approaches to build tunable structures for luminescent enhancement: 1) using already synthesized metallic nanocrystals resonant at the desired wavelengths as building blocks, we designed structures that would result in maximum emission enhancement. 2) Designing arrays of plasmonic nanostructures with the help of simulation software to be resonant at the desired wavelength and then fabricating them with top-down nanoscale fabrication techniques. In either approach, the resulting large area structures were macroscopically studied by steady state and time-resolved photoluminescence measurements to quantify the plasmonic effects on enhancement. We were able to achieve high enhancement factors in almost all of the structures and designs. Furthermore, we were able to identify and study various effects that play a role in plasmonic enhancement processes

Damage characterization of aircraft fuselage using vibrothermography technique-review and analysis

Vibrothermogrphy is a promising non-destructive technique that uses ultrasonic elastic waves to detect damages and is typically applied in the aerospace and automotive industries. This technique allows for defect selective imaging using thermal waves that are generated by ultrasound waves. In this paper, vibrothermography technique was applied to the aircraft fuselage to detect its damage. The influence of the damage on the temperature distribution at the damage region on the aluminum was investigated by finite element technique. Comprehensive understanding in edge crack in fuselage heating caused by local friction between crack surfaces was obtained

Prediction and detection of abnormal usage of an elevator

In this thesis we used machine learning to detect the anomalous use of elevators by measuring the behavior at any specific time. We examined the data for unusual patterns in comparison with observed samples from the history of the elevator. We investigated forecasting the future use of the elevator to define an abnormal behavior for elevators and tried to address this issue in two approaches. First, we used Long Short-Term Memory to forecast future usage, and we optimized the result by extracting features and removing the noisy part of the data. Then we compared actual usage with our prediction and used 99.7% confidence interval (three sigma rule) to find out anomalies. The second approach used a local outlier factor to find out the distance of each week’s usage of the elevator from the other weeks. Then we took the intersection of these two methods, performed a set of post-processing actions to decrease the ratio of false positives and remove anomalies which were not sustained

Serum Magnesium Levels in Children with Type 1 Diabetes Mellitus in Northwest Iran

Background: Type 1 Diabetes Mellitus (T1DM) is a chronic disorder that can cause microvascular and macrovascular damages in the long term as well as higher rates of mortality and morbidity in infectious diseases such as Covid-19. It has been discovered that the homeostasis of trace electrolytes like magnesium plays a crucial role in the pathogenesis of diabetes and its related complications. We aimed to determine serum magnesium levels in children with T1DM in northwest Iran and to evaluate the relationship between serum magnesium levels and glycemic control while also assessing several anthropometric and birth-time-related factors.Methods: This cross-sectional study gathered data from 50 patients with T1DM and 50 other healthy subjects matched for age and gender living in the northwest area of Iran. These children were tested during their visits to the children’s hospital of Tabriz. Magnesium levels and environmental factors were measured in all study subjects.Results: We found magnesium levels to be significantly lower in children with T1DM (p < 0.001). Hypomagnesemia was also seen in 58% of the case group, which was significantly more prevalent than the 6% in the control group (p <.001). We observed a negative correlation between serum magnesium and HbA1c levels in the diabetic group (r = -0.882, p <.001). No significant correlation was found between magnesium levels and duration of diabetes, age, and gender.Conclusion: We concluded that total serum magnesium is lower in children with T1DM, which correlates with glycemic control. Further and more extended studies should be conducted to assess the effect of correction of serum magnesium in diabetic children with hypomagnesemia on glycemic control and the risk of diabetic complications

Integrity assessment of preforms and thick textile reinforced composites for aerospace applications

Three-dimensional (3D) textile composites containing in-plane fibers and fibers oriented in the thickness direction offer some advantages over two-dimensional (2D) textile composites. These advantages include high delamination resistance and improved damage tolerance. Textile composites containing 3D textile preforms have mostly been developed by the aerospace industry for structural applications such as wing panels, landing gear, rocket nozzles, and the Orion capsule, and so forth. This thesis is devoted to structural integrity assessment of textile composites including 2D and 3D tufted composites by combining destructive and non-destructive techniques. In the first part of the thesis, non-destructive techniques including X-ray computed tomography (CT) and ultrasound-based techniques (UT) were used to detect two significant processinduced defects called fiber breakage and fabric misalignment. The second part focuses on studying of the influence of manufacturing defects introduced during the tufting process on the mechanical properties. Experimental results proved that X-ray CT facilitates the characterization of those two manufacturing defects as well as the architecture of the textile fabrics. Furthermore, mesoscale modeling of a 2D woven composite was successfully performed for the analysis of the fiber breakage defect influence and fiber architecture on wave propagation. Experimental results prove that tufting the preform assists in locking and restricting the yarn's movement in the preform. The threads used for tufting have a major influence on tensile strength, as stronger threads may give higher resistance. Tufting increases the compaction force due locking of fiber bundles, therefore, a higher compaction force is needed to obtain a fiber volume of up to 50 percent in comparison to an untufted preform. The drape behaviour of a tufted preform is influenced by tufting so that high drapability is observed for a tufted preform along with local variation of fiber bundle occurred around tufting reinforcements. The variation of preform geometry was achieved by laser scanning. Furthermore, the CT capability was investigated as a means for recognizing the shapes and locations of voids in composites. Tufted composites with transverse tufting suffer less reduction in the tensile strength than those with longitudinal tufting. Tufted composites are found to have lower fatigue life ithan untufted composites, while an improved compressive strength and tensile strength at high strain rate are observed. Tufting improves the mechanical properties of tufted honeycomb composites under local compression and bending loadings. Mostly, the damage initiates from resin-rich regions around the tufting reinforcements. The acceptance of 3D tufted composites for use in primary aerospace structures is highly dependent on the accuracy and reliability of experimental data to recognize the degree to which tufting reinforcements improve or degrade the mechanical properties. In this thesis, the correlation between the tufted preforms and composite properties and the changes to mechanical properties is discussed for a specific tufting configuration. Experimental data are reported on both the low-rate and high-rate static and fatigue strengths at various stress levels. Microstructural examination is carried out by using the high resolution microscopy and CT techniques. The results of this thesis contribute to the investigation of the integrity and damage tolerance in 3D tufted composites toward certifying purposes for future transport aircraft. Since the certification of tufted composites for aerospace applications is still problematic due to the lack of dependable non-destructive evaluation techniques for their inspection and those manufacturing factors can considerably influence their performance, this is an important problem to tackle in the field of aerospace composite engineering

Apolipoprotein E serum levels in children with Guillain-Barre Syndrome in northwest of Iran

Background: Guillain-Barre syndrome (GBS) is an acute immune-mediated disease that affects both adults and children. Many infectious and non-infectious conditions may trigger this disease. Apolipoprotein E (APOE) is a glycosylated protein that has a variety of lipid and non-lipid related functions. The present study aimed to evaluate the serum levels of APOE in children with GBS compared to healthy control subjects to evaluate the diagnostic and pathologic effects of APOE in GBS. Methods: In a cross-sectional design, 124 participants were divided into the GBS group (n=61) and the control group (n=63). Blood sampling and measurement of APOE were done according to the manual of the Human APOE ELISA kit. Demographic variables and further data about GBS patients were collected from patients' medical records. Weight and height were measured using SECA scales. The analyses were performed using SPSS Statistics 21.0 software and appropriate analytical tests. P-values of <0.05 were considered statistically significant. Results: Mean ±SD of APOE serum levels was 8.43±3.59 micrograms/ml in the GBS group and 35.28±11.18 micrograms/ml in the comparison group. The difference between the two groups was strongly significant (P<0.001). The mean level of protein in Cerebrospinal Fluid (CSF) in GBS patients was 184.36±19.09 mg/dl. There was not any significant difference in the demographic findings between the two groups. Conclusion: Our study demonstrated that the serum levels of APOE in children with GBS are lower compared to healthy subjects

Propeller‐Like Nanorod‐Upconversion Nanoparticle Assemblies with Intense Chiroptical Activity and Luminescence Enhancement in Aqueous Phase

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133596/1/adma201601261-sup-0001-S1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133596/2/adma201601261_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133596/3/adma201601261.pd