Wave overtopping and toe scouring at a plain vertical seawall with shingle foreshore : a physical model study

This paper describes a physical model study to investigate the wave overtopping and toe scouring at a plain vertical wall with a shingle foreshore. A matrix of 180 experimental test conditions were performed in a 2D wave flume, with an approximate scale of 1:50. The study investigates the baseline overtopping characteristics at a plain vertical wall on an impermeable 1:20 foreshore slope and compares the results with two permeable 1:20 shingle beach foreshores with prototype d50 values of 13 mm, and 24 mm respectively. For impulsive wave conditions, it was found that the mean overtopping rate was reduced by factor 3 for the d50 of 13 mm, and a factor of 4 for the d50 of 24 mm. For non-impulsive waves, the reduction factors were 1.5 for d50 of 13 mm and 2 for d50 of 24 mm. Prior to this study, limited design guidance was available to predict the mean overtopping discharges and mean sediment rates at vertical seawalls on permeable shingle foreshores. Therefore, a new set of prediction formulae are proposed in this study, based on the new laboratory test results, and a comparison with the available prediction methods in literature for vertical seawalls subjected to both impulsive and non-impulsive wave conditions

Experimental study on toe scouring at sloping walls with gravel foreshores

Sea defences, such as urban seawalls can fail due to the development of a scour hole at the toe of the structure. The scour depth or the information on ground levels at the structure toe is required for the sustainable management of coastal defences, due to its influence on the structural performance. This research reports and summarises the main findings of a new laboratory study on toe scouring at a smooth sloping wall with permeable gravel foreshore. A set of small-scale laboratory experiments of wave-induced scouring at sloping seawalls were conducted. Two gravel sediments of prototype d50 values of 13 mm and 24 mm were used to simulate the permeable 1:20 (V:H) gravel beach configurations in the front of a smooth 1 in 2 sloping wall. Each experiment comprised of a sequence of around 1000 random waves of a JONSWAP energy spectrum with a peak enhancement factor of 3.3. The relationship of the scour depth with toe water depth, Iribarren number, and wall slope were investigated from the test results of this work and through a comparison with available datasets in the literature. The results of this study showed that the relative toe water depth and Iribarren number influence the relative toe scour depth at a sloping structure on a shingle beach. Within the experimental limitations, the maximum toe scour depths were observed for the experiments under spilling and plunging wave attack

Determinants of Structural Change in the Dairy Sector

Even though the dairy products are not a staple food item, but they are necessary for humans as an excellent source of protein. The consumption of dairy commodities began a long time ago, and over time there has been an improvement in the processing to match the changes in the tastes. Small scale dairy production was the root of today’s dairy sector. However, now it is going on a large scale. This changed gradually through a process accompanied by different factors. This study aimed at identifying and understanding existing determinants and their role behind the change in the dairy sector. For this, peer-reviewed articles published by researchers around the world were obtained with all possible search combinations from reputed online databases. Statistical data were collected from reliable statistical data providers, and all activities were done focusing on the determinants of changing the dairy sector. The regulatory policy framework of dairy-producing countries, change in farm size, shift in consumption pattern, etc. were found as the most crucial factors behind the change. Possible suggestions required to keep pace with this massive change were discussed

Self-medication during COVID-19 outbreak: a cross sectional online survey in Dhaka city

Background: Self-medication is a common practice in Bangladesh as it provides a low-cost alternative for people, which involves inappropriate and injudicious use of medicines treat self-recognized symptoms by the people.Methods: A cross sectional online survey was conducted on 626 citizens by structured questionnaires during COVID-19 outbreak from April to May 2020 in Dhaka city, to observe the prevalence, pattern and sources of self-medication among the respondents with high socio-economic standings and education.Results: The prevalence of self-medication amid the outbreak of COVID-19 was 88.33% and only 179 (28.59%) took medication with doctors’ advice and remaining 447 (71.40%) respondents took the drugs as “self-medication” by other sources. The most frequently used prescription-only drug during the outbreak were ivermectin (77.15%), azithromycin (54.15%), doxycycline (40.25%). The common symptoms for which the respondent took self-medications were fever, throat pain, dry-cough and total 105 (16.77%) respondents took medications without having any symptoms. Almost 355 (85.33%) had taken medication without doing any test for COVID-19. This could be due to unusual distress, caused by high self-awareness of their health and buying capacity of medication.Conclusions: The study revealed the causes of self-medication as news of spread, effects and remedies in media channels, internet; mental stress of lockdown and isolation, insecurity and panic about scarcity of drug and healthcare support. High risks of developing antibiotic resistance, adverse drug reactions and financial loss was predictable with absence of strict regulatory enforcement to protect people and proper utilization resources during COVID-19 outbreak in Dhaka city

The Influence of Geometrical Shape Changes on Wave Overtopping: a Laboratory and SPH Numerical Study

This paper presents laboratory investigations of four “retrofit” suggestions for attenuating the overtopping from vertical seawall. Two-dimensional physical model experiments were performed on a vertical seawall with a 1:20 sloping foreshore. Additionally, a Lagrangian, particle based SPH methodology was employed to simulate the wave hydrodynamics and overtopping for the recurve configuration. The experimental and numerical results confirm satisfactory performance. For the tested configurations in the laboratory, the mean overtopping discharges decreased over 60% and maximum individual discharge decreased 40% on recurve wall under both impulsive and non-impulsive conditions. A significant reduction was also observed in mitigating overtopping discharge by using model vegetation and reef breakwater, while diffraction pillar was not found satisfactory

Acquaintance, approach and application of pharmacovigilance: questionnaire based study at a tertiary care teaching hospital in Dhaka

Background: Pharmacovigilance is proven as an effective monitoring mechanism for safety and efficacy of pharmaceutical products with the assistance of physicians, pharmacists, nurses, and other healthcare professionals to avoid undue physical, mental and financial suffering of patients. Thus, this study was conducted to assess awareness of pharmacovigilance among the healthcare service providers to evaluate the acquaintance, approach application (3A) of judicial reporting of ADRs and pharmacovigilance in a tertiary care teaching hospital in Dhaka.Methods: A pre-tested questionnaire-based study was done among the 5th year medical students, interns, doctors and nurses of Holy Family Red Crescent Medical College, Dhaka, Bangladesh to assess the overall status of acquaintance (knowledge), approach (attitude) and application (practice) pharmacovigilance. Total 417 questionnaires were distributed and 389 were included as valid, compiled and analysed using SPSS version 25.0.Results: Among the respondents, almost 78% of the nurses responded the right answers and doctors responded the lowest 29% on average. The average percentage of approach and application of pharmacovigilance was low in all the respondent groups. The poorest outcome was observed about reporting an adverse drug reactions (ADR) form by all respondents as 01% to 08%.Conclusions: The overall status of pharmacovigilance in a tertiary teaching hospital was found paradoxically low, that revealed the necessity of much more initiatives at the undergraduate and postgraduate academic curriculum and intensive motivation, training, monitoring should be addressed to ensure the safety of medication, rationality of drug use and accomplish the national pharmacovigilance programs

Laboratory investigation of overtopping at a sloping structure with permeable shingle foreshore

The vast majority of overtopping data applied in EurOtop (2018) has been made from small-scale measurements with impermeable foreshore slopes. This article describes a comprehensive two-dimensional experimental study conducted in a small-scale 1:50 wave flume. Results are presented for the overtopping performance at a 1 to 2 sloping wall, undertaken on both impermeable and permeable foreshore slopes. Within experimental limitations, the results demonstrated that the mean overtopping rate is reduced by up-to a factor of 4, when compared to the predictions reported for the impermeable slope. However, when comparing maximum individual wave-by-wave overtopping volumes, no significant differences were observed. These results are intended for practitioners and researchers predicting wave overtopping characteristics at sloping structures with permeable gravel foreshores

Small-Scale Turkey Farming in Bangladesh: Farming Practices, Profitability and Supply Chain Mapping

The study was conducted to know the existing turkey production system, supply chain mapping, and identifying the prospects and problems of turkey rearing in some selected areas of Bangladesh during October 2019 to December 2019. A total of 100 turkey raisers were surveyed following convenience method of sampling technique. The primary data were collected, analyzed accordingly and tabular presentation method was applied with the help of simple descriptive statistical measures e.g. frequency distributions, percentage, sum and means to illustrating the results. Profitability analysis was done on the basis of variable cost, fixed cost, return by using arithmetic means and percentages. The study revealed that 87 male and 13 female respondents were surveyed, of them cent percent found educated. About 56% turkey keeper’s main occupation was business, 27% service and 12% in farming while 88.57% involved with farming as secondary sources of income. Average landholding for homestead, cultivable and non-cultivable was 24.40, 129.71 and 29.47 decimal, respectively. About 59% farms started for commercial purpose, 32% for non-commercial purpose and 9% for both. About 60% respondents kept less than 50 turkeys and only 2% kept 501-1000 turkeys. Among the surveyed farms55% stopped their operation and 45% farms found running their business. Among the running farms cent percent were small-scale group. The average feed intake was 192.13 grams per day per bird at 20 weeks of age. Turkey laid on an average 139 eggs a year irrespective of variety and for hatching poults, the fertility and hatchability rate found between 65 to 100% and 50 to 90%, respectively. About 28% farmers experienced the deaths of turkey because of Cold, Pox, Ranikhet, Bird flu and unknown cases and 69.47% farmers took veterinary advice from Upazila Livestock Hospital and rest from other sources. Farmers to consumers were the most common and widely used marketing channel for egg, chick and adult turkey. The market intermediaries of turkey farm carried out different marketing functions e.g. buying and selling, pricing, transportation, sorting, distribution and market information. The average net return and benefit-cost ratio was BDT 127838.04 and 1.38, respectively for 50 turkeys per year. In the study, turkey rearing found some comparative benefit over chicken and ducks e.g. higher weight gain, forage eater, lower diseases rate and suitability for the country. The main problem of turkey rearing identified as market instability, lack of quality turkey feed, higher feed price, lack of proper marketing facility and training on turkey farming. In conclusion, the small-scale turkey farming could be a viable source of income for the rural people of Bangladesh after taking some remedial steps by the Government of Bangladesh for the aforesaid hindrances faced by the turkey farmers

Improved prediction of wave overtopping rates at vertical seawalls with recurve retrofitting

This study investigates the reduction in overtopping discharge along a vertical seawall through the implementation of a recurve retrofitting. A comprehensive set of physical modelling experiments were undertaken in a laboratory-scale wave flume at the University of Warwick, to investigate the wave overtopping processes under both swell and storm wave conditions. The tests measured overtopping discharges for impulsive and non-impulsive wave conditions. The effects of geometrical design of recurve retrofitting on overtopping reduction are examined by four configurations with varying overhang length and recurve hight. The study revealed that the reduction in overtopping is primarily determined by the length of the overhang in the recurve wall, while the influence of the recurve height is limited. A longer overhang length results in a more substantial decrease in overtopping discharges on the seawall crest. The results also highlight the role of incident wave steepness and the crest freeboard on the overtopping mitigation performance of the recurve walls. A new enhanced methodology is proposed to predict the wave overtopping from vertical seawalls with recurve retrofitting., considering the effects of freeboard and wave steepness. The findings of this study provide new important insight in the role of retrofitting as a robust intervention to improve the wave overtopping mitigation performance of seawalls. The predictive empirical formulae proposed by this study facilitate readily and accurate estimation of overtopping rates as a function of retrofitting geometrical design, allowing for wider application of retrofitting solutions

Effect of DLC Coating on Tribological Behavior of Cylinder Liner-piston Ring Material Combination When Lubricated with Jatropha Oil

AbstractThe expansion of modern engines would have been unfeasible without advanced lubricant chemistry and proper lubricant formulation. Introduction of diamond like carbon (DLC) coatings opens further possibilities in improving performance of engine and transmission components, which cannot longer be achieved only by lubricant design.DLC coatings show extremely good promise for a number of applications in automotive components as they exhibit excellent tribological properties. In this paper, the tribological performance of hydrogenated amorphous carbon (a-C: H)DLC coating with Jatropha oil was evaluated using a four ball Tribometer also with commercial synthetic lubrication oil (SAE 40) used as base lubricant. Experimental results demonstrated that the hydrogenated amorphous carbon (a-C: H)DLC coating exhibited better performance with Jatropha oil in terms of wear and friction under similar operating conditions compared to the uncoated stainless. Thus, usage of hydrogenated amorphous carbon (a-C: H)DLC coating with Jatropha oil in the long run may have a positive impact on engine life