Sharif Digital Repository

Abstract: Using adhesively bonded composite patch repairs has been increased in various industries to improve the structural integrity of cracked metallic structures in recent decades. Monitoring of crack propagation and composite patch debonding, as two dominant failure mechanisms in this repair technique, plays a significant role in the integrity assessment of the component. This research conducts an experimental investigation on the simultaneous monitoring of these two failure mechanisms in a cracked metallic specimen repaired by a composite patch. For this purpose, the electromechanical impedance method was used to evaluate the feasibility of recognizing the type of damage at any phase... 

The sensitivity of many in vivo applications necessitates investigating adversarial activities in micro-scale MC systems. On the other hand, macro-scale applications of MC are easier to launch security attacks on. In this paper, we study the problem of jamming attacks in MC, where a concentration transmitter releases a particular type of molecule to send its message over a diffusive channel to a transparent receiver. A jammer wishes to disrupt the communication either by transmitting the same molecule type or a reacting molecule type. We propose jamming-resistant coding schemes to counteract this attack. For this purpose, three jamming models based on different capabilities of attackers and... 

We revisit the problem of deciding whether a given curve resembles some part of a larger curve under a fixed Fréchet distance, achieving a running time of O(nm), for n and m being the number of segments in the two curves. This improves the long-standing result of Alt and Godau by an O(log(nm)) factor. Our solution is based on constructing a simple data structure which we call free-space map. Using this data structure, we obtain improved algorithms for several variants of the Fréchet distance problem, including the Fréchet distance between two closed curves, and the so-called minimum/maximum walk problems. We also improve the map matching algorithm of Alt et al. for the particular case in... 

Back in 1995, Alt and Godau gave an efficient algorithm for deciding whether a given curve resembles some part of a larger curve under a fixed Fréchet distance, achieving a running time of O(nm log(nm)), for n and m being the number of segments in the two curves, respectively. We improve this long-standing result by presenting an algorithm that solves this decision problem in O(nm) time. Our solution is based on constructing a simple data structure which we call free-space map. Using this data structure, we obtain improved algorithms for several variants of the Fréchet distance problem, including the Fréchet distance between two closed curves, and the so-called minimum/maximum walk problems.... 

Given a point set S and a polygonal curve P in Rd, we study the problem of finding a polygonal curve through S, which has minimum Fréchet distance to P. We present an efficient algorithm to solve the decision version of this problem in O(nk2) time, where n and k represent the sizes of P and S, respectively. A curve minimizing the Fréchet distance can be computed in O(nk2 log(nk)) time. As a by-product, we improve the map matching algorithm of Alt et al. by an O(log k) factor for the case when the map is a complete grap  

We prepared three ferrite nanocatalysts: (i) copper ferrite (CuFe 2O4) (ii) ferrite where cobalt was substituted by nickel (Nix Co1-x Fe2O4, with x=0, 0.2, 0.4, 0.6), and (iii) ferrite where nickel was substituted by zinc (Zn y Ni1-y Fe2O4 with y=1, 0.7, 0.5, 0.3), by the sol-gel method. The X-ray diffraction patterns show that the ferrite samples have been crystallized in the cubic spinel structural phase. We obtained the size of grains by field emission scanning electron microscopy images and their magnetic properties by vibrating sample magnetometer. Next, carbon nanotubes were grown on these nanocatalysts by the catalytic chemical vapor deposition method. We show that the catalytic... 

Applications of starch nanostructured-based packaging for food items have been discussed in this chapter. These films can perform a wide range of functions, create the appropriate stimulus response packaging following the needs of the food and have a supervised liberation impact on the functional ingredients in the film by combining with thermally-sensitive, gas-sensitive, moisture-sensitive or other multi-purpose packaging materials to create unique intelligent packaging. Even though starch-based active and intelligent packaging has issues with material selection, preparation and function, starch has undeniably emerged as the most feasible material to substitute petroleum-based conventional... 

A nanocomposite is a technologically advanced material composed of multiple nanoscale phases, wherein each phase displays dimensions ranging from 1 nm to 3 nm in size, leading to the formation of a unique multi-dimensional solid material. Nanomaterials such as nanoparticles, nanofibres and nanoclays are used in nanocomposites. Plastic's non-biodegradable and non-renewable qualities have been a significant drawback to their use, resulting in massive municipal waste and environmental issues. Despite this difficulty, no biodegradable polymers have been produced that combine all of the features and affordability of plastic. Starch, a naturally occurring polymer that can be mass-produced at a low... 

The current study aims to provide insights into the drying of agro products, with a specific focus on Capsicum annum L. (red pepper). Among open sun drying (OSD), polyethylene bag drying (PBD), and polycarbonate sheet drying (PCSD), PCSD was efficient requiring around 24 hours with a maximum yield of 350 g of dried product per 1000 g of supplied fresh peppers. The PCSD dried chili also showed greater retention of antioxidant markers (capsaicin and dihydrocapsaicin) than OSD and PBD as evidenced by UV-VIS spectroscopy. Additionally, the PCSD dried chili demonstrated highest antioxidant potential via ABTS (2, 2'-Azinobis-3-Ethylbenzothiazoline-6-Sulfonic Acid). Interestingly, the presence of... 

Substitutional effects of Mg2⁺ proceeding the structural, Fourier-transform infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometer characteristics of Sr₁₋ₓMgₓMn₂Fe₄O₁₁ R-type hexaferrite were systematically investigated for different concentrations (x = 0, 0.25, 0.75, 1.0). Sol-gel technique was adopted to fabricate the material. X-ray diffraction analysis confirmed samples exhibit a single-phase structure of MgMn₂Fe₄O₁₁. Lattice parameters (a and c) and V (unit cell volume) decreased with increasing Mg concentration. Also, a rise in dislocation density was observed, while crystallite size varied. FTIR spectra further corroborated the single-phase hexagonal... 

The intestinal tract microbiota influences many aspects of the dietary components on colon health and during enteric infections, thus, playing a pivotal role in the colon health. Therefore, the eugenol (EU) nano-emulsion effective concentration reported in our previous study against cancer cells should be explored for safety against beneficial microbes. We evaluated the sensitivity of Bifidobacterium breve and B. adolescentis against EU-loaded nano-emulsions at 0, 300, 600 and 900 µm, which were effective against colon and liver cancer cells. Both B. breve and B. adolescentis showed comparable growth ranges to the control group at 300 and 600 µm, as evident from the plate count experimental... 

Background: Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019. Methods: 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal... 

Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and... 

Background: Rigorous analysis of levels and trends in exposure to leading risk factors and quantification of their effect on human health are important to identify where public health is making progress and in which cases current efforts are inadequate. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a standardised and comprehensive assessment of the magnitude of risk factor exposure, relative risk, and attributable burden of disease. Methods: GBD 2019 estimated attributable mortality, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs) for 87 risk factors and combinations of risk factors, at... 

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a rules-based synthesis of the available evidence on levels and trends in health outcomes, a diverse set of risk factors, and health system responses. GBD 2019 covered 204 countries and territories, as well as first administrative level disaggregations for 22 countries, from 1990 to 2019. Because GBD is highly standardised and comprehensive, spanning both fatal and non-fatal outcomes, and uses a mutually exclusive and collectively exhaustive list of hierarchical disease and injury causes, the study provides a powerful basis for detailed and broad insights on global health trends and emerging challenges. GBD...