117 research outputs found
Experimental Evaluation of the Fatigue Performance and Self-Healing Behavior of Nanomodified Porous Asphalt Mixtures Containing RAP Materials under the Aging Condition and Freeze-Thaw Cycle
No full textFirst, porous asphalt (PA) pavement possesses a lower strength and lifetime compared to typical dense-grade asphalt mixtures due to its large empty space structure. Second, PA pavements' fatigue life and durability are affected significantly by climate factors; the two most critical factors being aging conditions and moisture actions. Third, because of the environmental concerns connected with producing or repairing asphalt pavements using only virgin materials, studies have recommended reusing reclaimed asphalt pavement (RAP) materials. On the other hand, their use in road pavement is negative to the fatigue performance of asphalt pavements, especially PA. Therefore, modifying PA mixtures containing RAP to address the mentioned issues is necessary. Researchers have found that modifying asphalt mixes using nanotechnology is one of the more effective methods. The four-point bending beam fatigue test is one of the most dependable tests to assess the fatigue performance of asphalt mixtures, and evaluating the fatigue resistance of nano-modified PA mixes containing RAP under laboratory conditions by performing this test is essential. This study aims to investigate the fatigue behavior of different compounds of PA mixtures modified with nano zinc oxide (NZ) (0%, 2%, 4%, 6%, and 8%) containing various contents of RAP materials (0%, 25%, and 50%) under normal, long-term aging, and freeze-thaw (F-T) cycle conditions. Moreover, the self-healing capability of these PA samples was evaluated using this test by performing two 24-h recovery periods following the first and second loading. It can be inferred from the result that although adding RAP and inducting long-term aging and moisture-damaged conditions negatively influenced PA mixes' fatigue lives, incorporating NZ caused increases in these values by averages of 114%. Besides, results indicated that applied rest periods were observed to significantly impact PA specimens' self-healing capability, resulting in longer fatigue life for them. On average, conventional and NZ-modified PA mixes with/without RAP could recover up to 32 and 48% of their fatigue resistance in all conditions.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Pavement Engineerin
The design of a robust and intelligent phased array Non-Contact Vital Signs (NCVS) sensor system
No full textFor the past few years, it has been the desire of the healthcare industry to have a non-invasive system capable of continuous, accurate, and long-term monitoring of human vital signs. Having a system that can measure and record vital signs, such as heart rates and respiration rates, is an invaluable tool for physicians who need to make rapid life-and-death decisions. Such a system would also be an effective tool to help physicians make better informed decisions when viewing a patient’s long-term monitored data. Therefore, there has been a large increase in research activities to develop a system that can monitor a patient’s vital signs and quickly transmit the information to healthcare professionals. Non-contact vital signs (NCVS) monitoring system are particularly attractive for long term vital signs monitoring because there are no wires, electrodes, wearable devices, nor contact-based sensors for the subjects to worry about.
In this thesis we will investigate improvements made to an existing Doppler-based non-contact vital signs (NCVS) biosensor we have built in Professor Donald Y. C. Lie’s RF/Analog SoC Lab. The main focus of this thesis will be on improving the effective range of the system and the creation of a “smart” system capable of detecting a patient’s location and movement. To determine the accuracy of the NCVS sensor, the heart rate measurements from the system are compared against an external contact-based piezoelectric finger sensor as a reference.
In previous works, the NCVS sensor performance was tested within a clutter-free anechoic chamber inside Dr. Lie’s RF/Analog SoC Lab. In this work, to examine the performance of the NCVS sensor in a more practical setting, all tests were performed within the typical Herman-Miller type office cubicle setting, inside a section of the RF/Analog SoC Lab. Additionally, I will detail the 5th and 6th generation revisions and improvement to the NCVS sensor.This thesis won 1st Place in the Texas Tech University Outstanding Thesis and Dissertation Award, Mathematics, Physical Sciences & Engineering, 2016.Embargo status: Restricted from online display. To request an access exception from the author, click on the PDF link to the left
Wuthering Heights: Making of A Free Woman in Male-chauvinist Victorian Society
No full textLooking through the lenses of Wuthering Heights, this paper investigates into the biographical elements of its author, Emily Bronte and fine-tunes her personal, social as well as cultural elements that prepared her to revolt against the contemporary Victorian patriarchal society and enabled her to create an epoch-making female character like Catherine who, while living in the very male-chauvinist Victorian society, excelled in restoring love, honor and self-respect of a woman. Keywords: Victorian, feminist, male-chauvinism, individualism, feminine
Hydroxyapatite/sericin composites: A simple synthesis route under near-physiological conditions of temperature and pH and preliminary study of the effect of sericin on the biomineralization process
No full textSynthesis of hydroxyapatite (HAp) and sericin (SS) nanocomposites was carried out by a simple precipitation method performed in batch in a stirred tank reactor (ST). The reaction was achieved by mixing a solution of calcium chloride dihydrate, in which SS was dissolved, with a solution of disodium hydrogen phosphate at 37 °C. Three experimental conditions were studied by varying the concentration of SS: HAp, HAp/SS1 (0.01 g/L of SS) and HAp/SS2 (1 g/L of SS). The chemical and physical properties of the resulting HAp/SS nanocomposites were studied using several techniques (Atomic Absorption Spectrometry, Ultraviolet-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Selected area diffraction (SAED) and Thermogravimetric analysis (TGA)). pH profile was also monitored over time for each experimental condition. The results revealed that nano single-phased HAp was formed with both rod and plate-like shape. Additionally, the particles have low crystallinity, characteristic similar to biological HAp. Regarding the influence of SS, one observed that with increasing SS concentration there is an increase in the mean particle size and the number of plate-like particles, as well as an increase in the aggregation degree and a decrease of the crystallinity. Further, the composites obtained have an inorganic/organic composition comparable to bone. Finally, in vitro cytotoxicity showed that the synthetized nanoparticles are non-toxic and cell viability is higher for HAp and HAp/SS samples when compared to a commercially available HAp. The produced materials can thus be considered suitable candidates for bone related applications.info:eu-repo/semantics/publishedVersio
Irish and Jordanian general student nurses’ attitudes towards people with mental illness (PWMI) and their relationship to cultural and religious beliefs
No full textBackground Attitudes held and cultural and religious beliefs of general nursing students towards individuals with mental health problems are key factors that contribute to the quality of care provided. Negative attitudes towards mental illness and to individuals with mental health problems are held by the general public as well as health professionals. Negative attitudes towards people with mental illness have been reported to be associated with low quality of care, poor access to health care services and feelings of exclusion. Furthermore, culture has been reported to play a significant role in shaping people’s attitudes, values, beliefs, and behaviours, but has been poorly investigated. Research has also found that religious beliefs and practices are associated with better recovery for individuals with mental illness and enhanced coping strategies and provide more meaning and purpose to thinking and actions. The literature indicated that both Ireland and Jordan lack baseline data of general nurses’ and general nursing students’ attitudes towards mental illness and associated cultural and religious beliefs. Aims: To measure general nursing students’ attitudes towards individuals with mental illness and their relationships to socio-demographic variables and cultural and religious beliefs. Method: A quantitative descriptive study was conducted (n=470). 185 students in Jordan and 285 students in Ireland participated, with a response rate of 86% and 73%, respectively. Data were collected using the Community Attitudes towards the Mentally Ill instrument and a Cultural and Religious Beliefs Scale to People with Mental Illness constructed by the author. Results: Irish students reported more positive attitudes yet did not have strong cultural and religious beliefs compared to students from Jordan. Country of origin, considering a career in mental health nursing, knowing somebody with mental illness and cultural and religious beliefs were the most significant variables associated with students’ attitudes towards people with mental illness. In addition, students living in urban areas reported more positive attitudes to people with mental illness compared to those living in rural areas
Critical parameters dictating efficiency of membrane-mediated drug transfer using nanoparticles
No full textCurcumin, a low molecular weight, hydrophobic compound, exhibits strong anti-cancer effects and has a high margin of safety. However, its poor water solubility, rapid metabolism and degradation make it relatively ineffective, but intracellular delivery using nanoparticles (NPs) would solve these problems. In this study, we formulated curcumin in two-structurally distinct NPs: a nanoemulsion (Cur-NE) and a Niosome (Cur-NIO), evaluated their in-vitro cytotoxic effects and examined their mechanisms of drug delivery. The use of Cur-NIO resulted in an unexpected increase in the intracellular accumulation of curcumin and induced a potent cytotoxic effect compared to Cur-NE. To our surprise, however, the effects of the endocytosis of NIO as well as that for NE on the cellular delivery of curcumin were negligible. Consequently, we concluded that Cur-NIO delivers curcumin directly to the cytosol via transfer from the NIO to the cell membrane. The results of Forster resonance energy transfer (FRET) and phase-transfer studies indicate that Cur-NIO exhibits efficient transfer into model membranes or organic interfaces. Moreover, we found that Cur-NE shows a poor transfer efficiency. This could be due to the presence of a hydrophobic oil core that reduces the probability of curcumin to transfer upon contact with the membrane. To the best of our knowledge, this is the first study of the effect of NP structure on the membrane-mediated transfer efficiency of low molecular weight, hydrophobic compounds
Green Synthesis of Silver and Gold Nanoparticles via Sargassum serratifolium Extract for Catalytic Reduction of Organic Dyes
No full textThe green synthesis of inorganic nanoparticles (NPs) using bio-materials has attained enormous attention in recent years due to its simple, eco-friendly, low-cost and non-toxic nature. In this work, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized by the marine algae extract, Sargassum serratifolium (SS). The characteristic studies of bio-synthesized SS-AgNPs and SS-AuNPs were carried out by using ultraviolet–visible (UV–Vis) absorption spectroscopy, dynamic light scattering (DLS), high-resolution transmission electron microscope (HR-TEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Phytochemicals in the algae extract, such as meroterpenoids, acted as a capping agent for the NPs’ growth. The synthesized Ag and Au NPs were found to have important catalytic activity for the degradation of organic dyes, including methylene blue, rhodamine B and methyl orange. The reduction of dyes by SS-AgNPs and -AuNPs followed the pseudo-first order kinetics
BinGold: Towards robust binary analysis by extracting the semantics of binary code as semantic flow graphs (SFGs)
No full textAbstractBinary analysis is useful in many practical applications, such as the detection of malware or vulnerable software components. However, our survey of the literature shows that most existing binary analysis tools and frameworks rely on assumptions about specific compilers and compilation settings. It is well known that techniques such as refactoring and light obfuscation can significantly alter the structure of code, even for simple programs. Applying such techniques or changing the compiler and compilation settings can significantly affect the accuracy of available binary analysis tools, which severely limits their practicability, especially when applied to malware. To address these issues, we propose a novel technique that extracts the semantics of binary code in terms of both data and control flow. Our technique allows more robust binary analysis because the extracted semantics of the binary code is generally immune from light obfuscation, refactoring, and varying the compilers or compilation settings. Specifically, we apply data-flow analysis to extract the semantic flow of the registers as well as the semantic components of the control flow graph, which are then synthesized into a novel representation called the semantic flow graph (SFG). Subsequently, various properties, such as reflexive, symmetric, antisymmetric, and transitive relations, are extracted from the SFG and applied to binary analysis. We implement our system in a tool called BinGold and evaluate it against thirty binary code applications. Our evaluation shows that BinGold successfully determines the similarity between binaries, yielding results that are highly robust against light obfuscation and refactoring. In addition, we demonstrate the application of BinGold to two important binary analysis tasks: binary code authorship attribution, and the detection of clone components across program executables. The promising results suggest that BinGold can be used to enhance existing techniques, making them more robust and practical
Continuous-Wave radars – applications, security, and target emulator
No full textRadars have been increasingly used for human-aware detection/activity recognition in the smart living sector, and to realize advanced driver-assistance systems (ADAS) and autonomous driving in the automotive industry. Prior to large-scale deployment of these sensors, it is essential to study the potential threats against these sensors that can interrupt their designed functionality, and comprehensively test them in scenarios that mimic real-world conditions. This dissertation presents three interlinked aspects related to continuous-wave (CW) radars: 1) their application as a sensing modality for smart homes, cities, and infrastructure, (2) a feasibility study on the possible spoofing attacks against CW radars, and (3) a low-cost CW radar target emulator for extensive testing under various background conditions.
It is crucial for the radar sensors deployed indoors to isolate the target of interest from unwanted clutter sources. A novel approach to suppress both stationary and moving clutter sources based on exponential moving average (EMA) filtering is proposed for indoor sensing. Although EMA-based filtering techniques were used for stationary clutter suppression in existing works, the proposed work addresses moving clutter suppression as well. The proposed approach removes all motion artifacts outside the characteristic frequency range of the human cardiopulmonary motion. A filter-and-subtract method is employed, where the output from two filters with different cut-off frequencies is subtracted so that all moving clutter signatures are attenuated while retaining the human target signatures. For experimental validation of the proposed approach, a 60-GHz frequency-modulated continuous-wave (FMCW) radar with single-input multiple-output (SIMO) architecture is used to uniquely identify the 2-D location of a stationary human subject, with various moving and stationary clutter sources in the background. By leveraging the digital beamforming (DBF) capability of the 60-GHz radar, a sideways hand gesture recognition technique is proposed that determines the instantaneous 2-D position of the hand at the start and end of the gesture. To detect the start and end time of the gesture, EMA filtering was applied to attenuate the reflections from the human body so that the signature of the gesture is prominent. The results presented can differentiate left-to-right and right-to-left lateral hand gestures.
A novel frequency-domain spoofing attack model is proposed to investigate the vulnerability of FMCW radars against malicious attacks. The proposed model avoids the need for precise nanosecond synchronization with the victim radar’s chirp transmission time. A single-sideband (SSB) mixer is the key component of the attack system, which introduces a frequency shift to the radio frequency (RF) chirp signal transmitted by the radar and retransmits the modulated chirp signal. Upon deramping operation on the radar's receiver chain, the introduced frequency shift by the SSB mixer translates to the beat frequency of the baseband signal, thereby creating an illusion of a real target. The frequency shift introduced can be varied to alter the range of the fake target. The theory of the spoofing model is developed, and a 5.8-GHz proof-of-concept spoofing system is designed to provide experimental validation. A hybrid-chirp FMCW waveform is proposed to distinguish a real target from a spoofing target to mitigate spoofing attacks.
Finally, a low-cost radar target emulator (RTE) for Doppler and FMCW radars is proposed. The proposed RTE is designed to emulate the radar’s response generated by two human activities: the Doppler artifacts of a human elbow-down gesture as seen by a Doppler radar, and the inherent chest motion of a stationary human subject measured by an FMCW radar. For the Doppler mode RTE, an SSB mixer is utilized to electronically modulate the CW signal transmitted by the radar to resemble a human hand gesture. The vital sign motion of a stationary human target is emulated using an analog phase shifter that serves as an integral part of the FMCW mode RTE. An SSB mixer integrated with the FMCW RTE showcased the ability to vary the range of the human target as well. The Doppler- and FMCW- mode target emulators are realized using 5.8 GHz commercially available off-the-shelf RF components. Due to the high similarity between the system-level architecture of an RTE and a spoofing system, the RTEs discussed above are set up as spoofing systems to deceive two state-of-the-art human detection algorithms.Embargo status: Restricted until 09/2023. To request the author grant access, click on the PDF link to the left
River dynamics and nanopaticles formation: A comprehensive study on the nanoparticle geochemistry of suspended sediments in the Magdalena River, Caribbean Industrial Area
No full textThe coastal zones on continental shelves are the main channels for the distribution of fluvial-sourced
suspended sediments (SSs). In the current research, the monthly average amount of SS draining into
the Caribbean Sea from the Magdalena River in northern Colombia was analyzed to detect nanoparticle
(NPs) containing potential hazardous elements (PHEs). The ecological authorities of Colombia claimed
that the climate change is the key reason behind land erosion and floods occurred in the last years;
therefore, an elaborate understanding of NP dynamics between the Magdalena River body and
streambed is an essential issue in SS research. In this work, the NP geochemistry of SS in the Magdalena
River estuary was studied from the perspective of water quality controls on SS sorting. The morphologies
and the structures of NPs (<100 nm) were examined by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), and selected area electron diffraction
(SAED)/micro-beam diffraction (MBD)/energy dispersive X-ray spectroscopy (EDS) techniques. The
average size of NPs was found to be greater than 2 nm and Al, Ti, Fe oxides, and other hazardous elements
were also detected in the SS. The obtained data confirmed that these typical categories of NPs caused the
occurrence-dependent intensification of a conjugative transmission rate associated with the regulators.
The advanced electron beam technique provided a clear insight into SS transportation; therefore, it could
be used as an essential instrument for river supervision/dynamics.Silva Oliveira, Marcos Leandro-0000-0001-6044-8737-600K. Saikia, Binoy-6b44536c-b3fb-4e94-8340-750845444a28-0Martinello, Katia Da Boit-d33cf8a0-3805-4230-a826-1239a32ebb0d-0Pinto Osorio, Diana Del Carmen-8cd35cac-193c-46df-b70e-dac9732ec441-0Fonseca Tutikian, Bernardo-7fe0e95f-c8e8-4401-9371-811b40d90c0c-0Silva Oliveira, Luis Felipe-5c1c9b54-f160-4f3c-bcd5-b9f532c778af-
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