On the stability of a class of shoreline planform models

AbstractThe evolution of beaches in response to the incident wave conditions has long attracted the attention of researchers and engineers. A popular mathematical model describing the change in the position of a single height contour on the coastline assumes that the beach profile is stable and the plan shape evolves due to wave-driven long-shore transport. Extensions of this model include more contours and allow for beach profile alteration through cross-shore transport of sediment. Despite this advantage, models with multiple contours remain relatively underused. In this paper we examine the stability of this class of model for the cases of one to three contours. Unstable modes may exist when there is more than one contour. These include short waves whose growth rate is strongly dependent upon wavenumber. For the case of three contours an additional long wave instability is possible. A necessary, but not sufficient, condition for instability is found. It requires a reversal of transport direction amongst the contours. The existence of these instabilities provides a possible explanation for the difficulties found in implementing computational multi-line models, particularly where structures alter the natural longshore transport rates so they satisfy, locally, the condition for instability

Three regimens for re-treatment failure of Sofosbuvir-based therapy for chronic hepatitis-C genotype-4: a cohort study

Despite the high sustained virologic response (SVR) rates of direct-acting antiviral (DAAs) therapy, a small number of patients does not eradicate the virus, and these patients represent a challenge. This study aims to compare the outcomes of three second-line regimens for DAAs-experienced patients with chronic hepatitis C (CHC). This prospective observational study was conducted at the Damanhur Viral Hepatitis Center from January 2017 to February 2020. We included patients with CHC who did not achieve SVR after the complete course of Sofosbuvir/Daclatasvir±Ribavirin (SOF/DAC±RBV). The primary endpoint was SVR-12 after re-treatment. This study included 360 patients (with a mean age of 51.53±11.38 years). Approximately 51.1% of the patients were males, and 65.5% had liver cirrhosis. All patients of group 1 (45 patients) received SOF/VEL/VOX over 12-weeks; SVR-12 was achieved in 44 patients (97.8%). Group 2 (28 patients) received SOF/DAC/RBV over 24-weeks; (one patient was lost during follow-ups and one patient discontinued treatment due to hepatic decompensation). SVR-12 was achieved in 25 patients (96.2%). Group 3 (287 patients) received SOF/Ombitasvir/Paritaprevir/Ritonavir/RBV) over 12-weeks. Eight patients were lost during follow-ups, and one patient discontinued treatment due to grade 4 adverse events. SVR-12 was achieved in 276 patients (99.3%). There was no difference between the groups regarding their age, gender distribution, baseline viral load or comorbidities. Adverse events (thrombocytopenia, anemia, hyperbilirubinaemia and prolonged INR) were significantly higher in group 3, while group 1 did not experience any. The three studied retreatment regimens can be used for DAAs treatment-experienced patients considering availability. The SOF/VEL/VOX combination had the least adverse events

Data-driven and hybrid coastal morphological prediction methods for mesoscale forecasting

It is now common for coastal planning to anticipate changes anywhere from 70 to 100 years into the future. The process models developed and used for scheme design or for large-scale oceanography are currently inadequate for this task. This has prompted the development of a plethora of alternative methods. Some, such as reduced complexity or hybrid models simplify the governing equations retaining processes that are considered to govern observed morphological behaviour. The computational cost of these models is low and they have proven effective in exploring morphodynamic trends and improving our understanding of mesoscale behaviour. One drawback is that there is no generally agreed set of principles on which to make the simplifying assumptions and predictions can vary considerably between models. An alternative approach is data-driven techniques that are based entirely on analysis and extrapolation of observations. Here, we discuss the application of some of the better known and emerging methods in this category to argue that with the increasing availability of observations from coastal monitoring programmes and the development of more sophisticated statistical analysis techniques data-driven models provide a valuable addition to the armoury of methods available for mesoscale prediction. The continuation of established monitoring programmes is paramount, and those that provide contemporaneous records of the driving forces and the shoreline response are the most valuable in this regard. In the second part of the paper we discuss some recent research that combining some of the hybrid techniques with data analysis methods in order to synthesise a more consistent means of predicting mesoscale coastal morphological evolution. While encouraging in certain applications a universally applicable approach has yet to be found. The route to linking different model types is highlighted as a major challenge and requires further research to establish its viability. We argue that key elements of a successful solution will need to account for dependencies between driving parameters, (such as wave height and tide level), and be able to predict step changes in the configuration of coastal systems

Wear performance and mechanical properties of MWCNT/HDPE nanocomposites for gearing applications

MWCNT/HDPE nanocomposite spur gears prepared in concentrations of 0, 0.5, 1, 1.5, 2, and2.5% by weight using centrifugal ball milling dispersion method followed by CNC milling.SEM examination revealed a sound dispersion of the MWCNT in the HDPE matrix until2 wt.%. Nanocomposites exhibited higher decomposition temperature and thermal sta-bility than neat HDPE. Yield strength increased linearly in nanocomposites up to 2 wt.%,and then it saturated. Nanofillers\u27 addition steadily increased the young\u27s modulus up toa weight fraction of 1.5 %, surging rapidly between 1.5 to 2 wt.%. In contrast, its rate ofincrease declined between 2 and 2.5 wt.%. The Taber abrasion test showed a reduction inwear loss of nanocomposites. The nanocomposites\u27 toughness increased between 0 (neatHDPE) and 1.5 wt.% of MWCNT but declined at higher concentrations due to transition fromductile to brittle nature. At a torque of 5 N-m, the wear performance increased consistentlywith the increase in the concentration of nanofillers. At 10 N-m, 2.5 wt.% nanocompos-ite gears displayed a decline due to the increased brittleness. Satisfactory dispersion anddeveloped interphase fervently contributed to the load transfer and mechanical properties.Nanofillers improved the wear resistance, hardness, and lowered plastic deformation. Thegear damage mechanism changed from thermal bending to tooth cracking and deflection inthe nanocomposite gears. The 2 wt.% MWCNT/HDPE nanocomposites emerged as potentialgearing materials with enhanced hardness, tensile properties, uniform dispersion, thermalstability, wear performance, and reasonable toughness

CUMULATIVE EFFECTS OF CHANNEL AND EBB SHOAL DREDGING ON INLET EVOLUTION IN SOUTHWEST FLORIDA, USA

This paper describes analysis and numerical modeling of tidal inlets in southwest Florida, where coverage of large temporal and spatial scales is necessary. A methodology is introduced for examining the response of complex inlet systems to dredging, including modeling of regional hydrodynamics, wave-current interaction, sediment transport, and application of the Inlet Reservoir Model. A case study for Longboat Pass, Florida, demonstrates this methodology. Longboat Pass is one of several tidal connections between the Gulf of Mexico and the Sarasota Bay system. The study covers evolution of Longboat Pass from 1880 to present. The analysis begins with natural conditions that existed before dredging or inlet modifications and investigates how inlet evolution is influenced by navigation improvements and mining of the ebb shoal for beach nourishment

A Framework for Adopting a Sustainable Reverse Logistics Service Quality for Reverse Logistics Service Providers: A Systematic Literature Review

Reverse logistics has become a competitive need for sustainability. Lack of resources to apply reverse logistics solutions has severely impacted many supply chains’ costs and customer service, making it impossible to meet the expectations of return processing. In those conditions, client demands for higher service quality are the main drivers of effective sustainability operations. This study aims to establish the sustainable reverse logistics service quality (SRLSQ) theoretical framework offered by reverse logistics services providers (RLSPs). The study conducts a systematic methodology protocol by examining reliable academic periodicals using PRISMA guidelines based on the research scope and identified 56 papers from 2011–2022, with the main research focus on SSQ and RLSQ dimensions to develop a research framework. By re-evaluating those factors using the SRLSQ framework and by including sustainability into the service quality approach, this study expanded the practicability of reverse logistic service quality and sustainable service quality. The results point to a knowledge gap when it comes to quantifying the impact of reverse logistics operation process through a triple bottom line approach on customer outcomes, relationship quality (RQ), and mediation of operation risk factor, which could be examined within various contexts in subsequent work

A Framework for Adopting a Sustainable Reverse Logistics Service Quality for Reverse Logistics Service Providers: A Systematic Literature Review

Reverse logistics has become a competitive need for sustainability. Lack of resources to apply reverse logistics solutions has severely impacted many supply chains’ costs and customer service, making it impossible to meet the expectations of return processing. In those conditions, client demands for higher service quality are the main drivers of effective sustainability operations. This study aims to establish the sustainable reverse logistics service quality (SRLSQ) theoretical framework offered by reverse logistics services providers (RLSPs). The study conducts a systematic methodology protocol by examining reliable academic periodicals using PRISMA guidelines based on the research scope and identified 56 papers from 2011–2022, with the main research focus on SSQ and RLSQ dimensions to develop a research framework. By re-evaluating those factors using the SRLSQ framework and by including sustainability into the service quality approach, this study expanded the practicability of reverse logistic service quality and sustainable service quality. The results point to a knowledge gap when it comes to quantifying the impact of reverse logistics operation process through a triple bottom line approach on customer outcomes, relationship quality (RQ), and mediation of operation risk factor, which could be examined within various contexts in subsequent work

Advances in sustainable grinding of different types of the titanium biomaterials for medical applications: A review

This review discusses various grades of titanium biomaterials and their sustainable grindability for application in the medical field. Titanium biomaterials are most commonly utilized for medical applications due to their exceptional characteristics such as high corrosion resistance and biocompatibility. The presented review looks at the principal requirements of titanium for medical applications, such as some good mechanical properties, biocompatibility, corrosion, wear resistance properties, and processability that facilitate the successful implantation of implants. It discusses the various types of titanium alloys that are commercially available and, more specifically, used for medical applications. It highlights the properties of different grades of titanium alloys and further narrows down its primary focus on applications, advantages, and shortcomings of commercially available titanium biomaterials. Machining titanium alloys is a difficult task due to their inherent properties such as low thermal conductivity and chemical reactivity at high temperatures and usually results in changes in metallurgy and surface integrity at the machined surface. Conventional machining, which has been the main machining method, has some limitations related to environmental hazards, cutting fluid costs, and operator health issues that have necessitated the development of sustainable machining. The emphasis in this review has been placed on sustainable grinding techniques such as MQL machining, cryogenic machining, nano-particle MQL machining, high-pressure machining, and solid lubrication machining used to grind titanium alloys and their benefits and limitations. Finally, the review will highlight some of the potential areas for future research and trends on different cooling and lubrication methods in the sustainable grinding of titanium alloys for medical applications. It is believed that this review will be of great benefit to the industries involved in manufacturing titanium-based medical implants

Characterization and Evaluation of Engineered Coating Techniques for Different Cutting Tools-Review

Coatings are now frequently used on cutting tool inserts in the metal production sector due to their better wear resistance and heat barrier effect. Protective hard coatings with a thickness of a few micrometers are created on cutting tools using physical or chemical vapor deposition (PVD, CVD) to increase their application performance. Different coating materials are utilized for a wide range of cutting applications, generally in bi-or multilayer stacks, and typically belong to the material classes of nitrides, carbides, carbonitrides, borides, boronitrides, or oxides. The current study examines typical hard coatings deposited by PVD and CVD in the corresponding material classes. The present state of research is reviewed, and pioneering work on this subject as well as recent results leading to the construction of complete "synthesis-structure-property-application performance" correlations of the different coatings are examined. When compared to uncoated tools, tool coatings prevent direct contact between the workpiece and the tool substrate, altering cutting temperature and machining performance. The purpose of this paper is to examine the effect of cutting-zone temperatures on multilayer coating characteristics during the metal-cutting process. Simplified summary and comparisons of various coating types on cutting tools based on distinct deposition procedures. Furthermore, existing and prospective issues for the hard coating community are discussed

Experimental design of Al2O3/MWCNT/HDPE hybrid nanocomposites for hip joint replacement

Fracture in the hip joint is a major and quite common health issue, particularly for the elderly. The loads exploited by the lower limbs are very acute and severe; in the femur, they can be several folds higher than the whole weight of the body. Nanotechnology and nanocomposites offer great potential in biomedical applications. The organic materials are more biocompatible. Mechanical properties like strength and hardness are challenging parameters which control the selection of a joint. HDPE in its pure form has been successfully used as a prosthetic foot (external) but failed as an implant material due to limited mechanical properties. High-density polyethylene thermoplastic polymer (HDPE) and multi-walled carbon nanotubes (MWCNT)/Nano-Alumina is selected as a potential material for a biomedical implant and its mechanical properties and biocompatibility have been discussed. HDPE/MWCNT/Alumina (Al2O3) nanocomposites have not been explored yet for prosthetic implants. These nanocomposites were prepared in this investigation in different compositions. Prepared material has been physiochemically characterized to check the morphology and the structure. MWCNTs enhanced hardness and elastic modulus of the HDPE. Optimization of the material composition revealed that hybrid composite with structure (2.4% Al2O3 and 0.6% MWCNT) exhibits better mechanical properties compared to other ratios with 3% MWCNTs and 5% MWCNTs. Thermal gravimetric analysis (TGA) dedicates that the percentage of crystallization has been increased to 6% after adding MWCNT to HDPE. The moisture absorption decreased to 90% with 5% MWCNT. Experimental results of Colorimetric assay (MTT) of a normal human epithelial cell line (1- BJ1) over Al2O3/MWCNT@HDPE showed <20% cytotoxic activity, proving its acceptance for medical use. HDPE/MWCNT/Al2O3 nanocomposites emerged as a candidate material for artificial joints