Numerical investigation of Von Karman swirling bioconvective nanofluid transport from a rotating disk in a porous medium with Stefan blowing and anisotropic slip effects

In recent years, significant progress has been made in modern micro- and nanotechnologies related to applications in micro/nano-electronic devices. These technologies are increasingly utilizing sophisticated fluent media to enhance performance. Among the new trends is the simultaneous adoption of nanofluids and biological micro-organisms. Motivated by bio-nanofluid rotating disk oxygenators in medical engineering, in the current work, a mathematical model is developed for steady convective Von Karman swirling flow from an impermeable power-law radially stretched disk rotating in a Darcy porous medium saturated with nanofluid doped with gyrotactic micro-organisms. Anisotropic slip at the wall and blowing effects due to concentration are incorporated. The nano-bio transport model is formulated using non-linear partial differential equations (NPDEs), which are transformed to a set of similarity ordinary differential equations (SODEs) by appropriate transformations. The transformed boundary value problem is solved by a Chebyshev collocation method. The impact of key parameters on dimensionless velocity components, concentration, temperature and motile microorganism density distributions are computed and visualized graphically. Validation with previous studies is included. It is found that that the effects of suction provide a better enhancement of the heat, mass and microorganisms transfer in comparison to blowing. Moreover, physical quantities decrease with higher slip parameters irrespective of the existence of blowing. Temperature is suppressed with increasing thermal slip whereas nanoparticle concentration is suppressed with increasing wall mass slip. Micro-organism density number increases with the greater microorganism slip. Radial skin friction is boosted with positive values of the power law stretching parameter whereas it is decreased with negative values. The converse response is computed for circumferential skin friction, nanoparticle mass transfer rate and motile micro-organism density number gradient. Results from this study are relevant to novel bioreactors, membrane oxygenators, food processing and bio-chromatography

Distribution of Mode I Stress Intensity Factors for Single Circumferential Semi-Elliptical Crack in Thick Cylinder

In this paper, mode I stress intensity factors (SIFs) are calculated numerically by finite element software ANSYS, for a single semi-elliptical circumferential crack on a thick cylinder. The examined cracks were located either on the external or internal surface of the cylinder and subjected to two different types of loadings, tension and internal pressure, applied separately. To present results in a more comprehensive form, dimensionless analysis is used, and a wide variation limit of parameters that define the crack geometry is considered. The ratio of crack depth to crack length ranging between 0.4 to 1.2, the ratio of crack depth to cylinder wall thickness vary between 0.2, 0.5 and 0.8, and the ratio of the cylinder wall thickness to the cylinder internal radius 0.25. Based on the obtained results, distributions of SIFs found to be symmetric along the crack front. The location where the maximum SIFs on the crack front attained is strongly affected by the change of aspect ratio, and external cracks generally exhibit a higher SIFs than those of internal cracks. It is also found a significant effect for the relative depth of the crack on SIFs value, which could accelerate the fracture process

Comparative computational study of mechanical behavior in self-expanding femoropopliteal stents

The use of the stent to treat peripheral artery disease (PAD) is increased and the proportion of failures also increases. The femoropopliteal artery (FPA) experiences a high deformation ratio compared to the cardiovascular artery due to limp flexion and daily activities that could lead to stent failure, as well as increasing the number of observed mortality and morbidity. In the present work, two of the common PAD stent design models represented as STENT I and STENT II were analyzed by using of finite element method (FEM) to simulate the most mechanical loading modes that could occur in FPA, such as axial tension and compression, torsion, three-point bending and radial compression to give a good understanding of deformation that affected stent inside the in-vivo. The gradual force load was used to simulate all modes, the force values are 0.25 N, 0.5 N, 1.5 N, 2.5 N, 3.5 N and 5.5 N until the stent models obtain the yield-point. The comparison of stent models (STENT I, STENT II) was performed in terms of graphs of total deformation, force-stress and stress-strain for all test modes. The similarity ratio of the total deformation in axial tension and the compression mode for STENT I and STENT II was 17% and that may indicate that STENT I obtained a high deformation value instead of STENT II, while, the torsion similarity ratio was 86% which could show a good agreement in this mode, as well as the similarity ratio, was 78% of the total three-point bending deformation and the value of the similarity ratio in the radial compression mode was 23%. Still unclear what is the clinical mode of mechanical deformation that is more important than others with changing the length of the lesion and stent diameter, and the fatigue life test provides a better understanding of the mechanical tests that must be sought

Exploiting Witness for Traffic Simulation

Traffic congestion in urban cities is an increasing problem. Not only does it lead to an increase in pollution, but the time spent waiting in traffic queues wastes valuable time in addition to causing frustration. A system that can control and manage traffic efficiently is one way that this issue can be reduced. A specific road traffic intersection in South Manchester, UK, was selected for investigation as it experiences high levels of traffic flow through it during the evening peak time. This has led to large queues and long waiting times due to the fixed timings of the traffic lights. This paper explores strategies to better control the traffic flow through it. A model of the selected traffic junction has been built using Witness simulation software. Data for this junction has been obtained partially from observations and mostly from traffic surveys enabling a simulation of the traffic flow. Analysing the results allowed two alternative scenarios to be developed and simulated. Results from one of the scenarios showed noticeable reductions in the average queue waiting times at the traffic junction

Cost analysis of psoriasis treatment modalities in Malaysian public hospitals

Psoriasis imposes a great economic burden as a result of higher expenditures for different interventions, diagnostic procedures, pharmaceuticals and loss of productivity. Less is known about the economic impact of psoriasis treatment in Asean region. The aim of this research was to calculate the costs associated with four psoriasis treatment modalities. A prospective cohort study was conducted in five hospitals involving 91 moderate to severe psoriasis patients. Costs were calculated from the societal perspective using the principle of Step Down and Activity Based Costing (ABC) within a six (6) months follow-up duration. The components of the costs borne by the provider were inpatient cost, cost of medication, laboratory investigation and radiology. Patient’s cost included out of pocket expenses, travelling cost and loss of productivity. Cost per patient per day was RM1,105.24 (inpatient) (US$315.94) and RM298.02 (outpatient) (US$85.19). Medication accounted for almost 90% (RM457,014.00) (US$130 638.45) of the total provider cost. Meanwhile, loss of productivity represented 84$47,862.80) of the total patient’s cost. Biologic treatment exhibited the highest cost which was RM342,377.00 (US$97,869.21), followed by systemic treatment (RM105,607.00) (US$30,187.99), topical treatment (RM38,280.00) (US$10,942.42) and topical phototherapy treatment (RM21,824.00) (US$6,238.44). Understanding the relationship between direct and indirect costs from both perspectives is important to accurately identify and evaluate effective treatment for psoriasis

HOUSING AFFORDABILITY STRESS: A LITERATURE SURVEY AND SOME EVIDENCE FROM MALAYSIA

Housing affordability stress has become an economic challenge to households in several countries, including Malaysia. Housing quality is the fundamental factors that affecting the wellbeing of the households. However, the rise in house price has squeezed the purchasing power of households in housing ownership and significantly diminishing the quality of life. The extensive gap between house prices and household’s affordability and therefore some households forced to rent poor-quality housing and neigbourhood, thus lead to housing stress and weakening a household’s well-being. In addition, housing needs to be equipped basic standard, providing reasonable access to employment and community services that is available at a cost which does not cause substantial hardship to the occupants. Thus, the aim of this paper is to explore the theoretical review of housing stress and empirical literature. There are associations between the housing stress measure on affordability and wellbeing, including financial stress, health and neighbourhood quality. Further, governments need to adopt more effective housing policies if they are to meet the needs of the households

A practical approach to synthesize polyamide thin film nanocomposite (TFN) membranes with improved separation properties for water/wastewater treatment

TFN membranes containing 0.05 or 0.10 w/v% surface-functionalized TNTs in a PA selective layer were synthesized for better performances in water/wastewater treatment.</p

A casemix: congestive heart failure readmission rate and its associated factors in a tertiary teaching hospital in Kuala Lumpur

Cardiovascular mortality is within the top five causes of death from non-communicable disease based on World Health Organization profile. Around 20% of heart failure patients are readmitted within 30 days worldwide. Readmission within 30 days for congestive heart failure often related to non-compliant to fluid restriction, natural progression of the disease or pre-mature discharge. The study aims to evaluate the 30 days readmission rate of congestive heart failure in Universiti Kebangsaan Malaysia Medical Centre (UKMMC) from the year 2016-2017 using casemix data and to determine the associated factors related to it. Based on the data coding, cost of readmission incurred was calculated. The 30-days readmission rate of heart failure to UKMMC in the year 2016-2017 was 53.5% & 43.5%, higher than the developed countries standard but similar to that of local teaching hospitals. After adjustment, age and level of severity are the only significant associated factors for the 30-days readmission rate. Shorter average length of stay (ALOS) & lower extra-tariff were achieved for readmission of heart failure. Total of RM80,329.73 was saved in the year 2017 from prompt treatment and comprehensive care plan of treating 19.3% level 3 severity patients at level 1 ALOS and tariff-cost. The 30-days readmission rate for heart failure in UKMMC was comparable to local teaching hospitals. The reduction of 30-days readmission rate in 2017 saved much cost, shows good clinical governance and advanced treatment strategy. Casemix can be used to guide budget allocation for the cardiology department of UKMMC