Numerical investigations of heat transfer enhancement in a house shapedcorrugated channel: combination of nanofluid and geometrical parameters

Improving the heat transfer rate is one of the main issues at the design stage of different thermal devices for various industries. In this research, a numerical simulation is performed to investigate the combined influences of nanofluid and various parameters designs of a house-shaped corrugated channel on the thermal and hydraulic performance under uniform heat flux of 10 kW/m2 and Reynolds number range of 10,000–30,000. In respect to the fluid medium, SiO2 nanoparticles are used and investigated with volume fraction up to 0.08. The impacts of geometrical parameters including height-to-width ratio (h/W), pitch-to-length ratio (p/L), and house ratio (e/r) on thermal and hydraulic characteristics are evaluated. The findings show that the (h/W) ratio has more influence on heat transfer promotion than the (p/L) ratio. At Reynolds number 30,000, there is a 16.63% increment in average Nusselt number due to a decrease of the (p/L) ratio from 0.175 to 0.075, while the increment 92.28% is achieved by an increase of the (h/W) ratio from 0.0 to 0.05. Heat transfer increases with roof height (r) and decreases with the vertical height of the house-shaped corrugation (e). The findings detect that a h/W of 0.05 with a p/L of 0.075 and e/r=0.6667 are optimum parameters that showed significant improvement in thermal performance. Moreover, new correlations for the Nusselt number and friction factor were developed and reported. Using nanofluid with the current channel is a useful source of reference to enhance thermal performance and produce more compact heat exchangers

Correlation Abnormal Ankle-Brachial Index and Multivessel Coronary Artery Disease in Acute Coronary Syndrome Patients

BACKGROUND: Many studies showed the association between peripheral artery disease (PAD) and coronary artery disease (CAD). The anklebrachial index (ABI) was a simple, noninvasive, and not expensive test that showed high sensitivity and specificity in the diagnosis of PAD. Previous studies showed PAD correlation with the number of coronary artery lesions and higher complexity of the lesions. These correlations might contribute to worse cardiovascular outcomes, especially acute coronary syndrome (ACS) cases. Aim of this study is to evaluate the correlation abnormal ABI with the risk of ACS patients to have multivessel coronary artery lesions.METHODS: This was a retrospective analytical casec ontrol study. The data were taken from Dr. Wahidin Sudirohusodo Hospital medical records from November 2015 to February 2016. The inclusion criteria were (>18 years old) patients with ACS who had underwent ABI examination and coronary angiography.RESULTS: The prevalence of patients with ST-elevation myocardial infarction (STEMI) was lower than non-ST elevation ACS (NSTE-ACS). The prevalence of patients with abnormal ABI was 43.3% and patients with multivessel CAD was 65%. Male patients dominated the ACS population with 73.3%, about half of patients were smoking, and 86.7% had dyslipidemia. Patients with abnormal ABI and multivessel disease had greater number than patients with normal ABI (p=0.025). Analysis with binary logistic regression model showed abnormal ABI(odd ratio [OR] 4.83; p=0.021) and male sex (OR 19.35; p=0.010) were associated with greater risk of multivessel CAD.CONCLUSION: An abnormal ABI is associated with greater risk of multivessel CAD in ACS patients

Maintaining Seed Quality of Maize and Wheat through Dry Chain Technology in Pakistan

Seed is inevitably deteriorated during storage and higher seed moisture content is the primary cause of this decline in seed quality. Dry Chain is a valuable tool, by using moisture proof hermetic containers to preserve seed quality throughout supply chain. This study evaluated and compared the performance of wheat and maize seed in different hermetic storage packaging (Super bag, Anaaji bag and drum) with conventionally used woven polypropylene bags after six months storage in ambient conditions. Seed moisture content was increased up to 11.53 and 13.55% in wheat and maize respectively when packed in polypropylene bags while it remained low (approximately 10 and 11.4% in wheat and maize respectively) when packed in hermetically sealed bags and drum. Germination was maintained in both cereal seeds stored in hermetically sealed Super bag, anaaji bag and drum while it reduced in polypropylene bags as compared to initial seed quality. Seed stored in polypropylene bag deteriorated quickly, which resulted in loss of seed vigour as indicated by higher malondialdehyde contents and electrical conductivity of seed leachates. It can be concluded that maintenance of seed dryness with hermetic storage is useful in preservation of seed quality and related attributes under high relative humidity environment

Bandgap narrowing in Mn doped GaAs probed by room-temperature photoluminescence

The electronic band structure of the (Ga,Mn)As system has been one of the most intriguing problems in solid state physics over the past two decades. Determination of the band structure evolution with increasing Mn concentration is a key issue to understand the origin of ferromagnetism. Here we present room temperature photoluminescence and ellipsometry measurements of Ga_{100%-x}Mn_{x}As alloy. The up-shift of the valence-band is proven by the red shift of the room temperature near band gap emission from the Ga_{100%-x}Mn_{x}As alloy with increasing Mn content. It is shown that even a doping by 0.02 at.% of Mn affects the valence-band edge and it merges with the impurity band for a Mn concentration as low as 0.6 at.%. Both X-ray diffraction pattern and high resolution cross-sectional TEM images confirmed full recrystallization of the implanted layer and GaMnAs alloy formation.Comment: 24 pages, 7 figures, accepted at Phys. Rev. B 201

CONCENTRIC TUBE-FOULING RIG FOR INVESTIGATION OF FOULING DEPOSIT FORMATION FROM PASTEURISER OF VISCOUS FOOD LIQUID

This paper reports the work on developing concentric tube-fouling rig, a new fouling deposit monitoring device. This device can detect and quantify the level of fouling deposit formation. It can also functioning as sampler for fouling deposit study, which can be attached at any food processing equipment. The design is initiated with conceptual design. The rig is designed with inner diameter of 7 cm and with tube length of 37 cm. A spiral insert with 34.5 cm length and with 5.4 cm diameter is fitted inside the tube to ensure the fluid flows around the tube. In this work, the rig is attached to the lab-scale concentric tube-pasteurizer to test its effectiveness and to collect a fouling sample after pasteurization of pink guava puree. Temperature changes are recorded during the pasteurization and the data is used to plot the heat transfer profile. Thickness of the fouling deposit is also measured. The trends for thickness, heat resistance profile and heat transfer profile for concentric tube-fouling rig matched the trends obtained from lab-scale concentric tube-pasteurizer very well. The findings from this work have shown a good potential of this rig however there is a limitation with spiral insert, which is discussed in this paper

Post-traumatic stress disorder among health care providers two years following the Israeli attacks against Gaza Strip in August 2014: Another call for policy intervention

This study aimed to assess the level of posttraumatic stress disorder and to examine the relationship between exposure to war stress and posttraumatic symptoms among health care providers two years following Israeli offensives against Gaza Strip in 2014. Methodology: A cross-sectional design was used for this study. We targeted all nurses and doctors working in three governmental hospitals in the Gaza Strip who worked with victims of the 2014 war, more specifically, those who were working in emergency departments, intensive care units, operating rooms, surgical departments, and burn units. A demographic sheet and Impact Event Scale-Revised were used in this study. The Impact Event Scale-Revised has three sub-scales; intrusion, avoidance, and hyper-arousal. Results: The results showed that 291 (89.3%) out of 2444 participants had scores more than 35 (threshold cut-off point) on Impact Event Scale-Revised. Scores ranged from eight to 80 with a mean of 52.71. Females had higher levels of stress (55.33) than males (50.82) and nurses (52.67) had more stress than physicians (47.38). The most frequent symptoms of trauma subscales was “Intrusion” (mean=19.99), followed by “Avoidance” (mean=17.60), and then “Hyper-arousal” (mean=14.12). Level of trauma symptoms were not affected by place of living, hospital of work, while level of education had impacted level of trauma. Conclusion: The findings showed that health care providers still suffer from severe posttraumatic symptoms two years after exposure to a prolonged war stress. This level of trauma among health care providers warrants intervention programs to reduce stress and trauma among Gaza health care providers after the war.This study aimed to assess the level of posttraumatic stress disorder and to examine the relationship between exposure to war stress and posttraumatic symptoms among health care providers two years following Israeli offensives against Gaza Strip in 2014. Methodology: A cross-sectional design was used for this study. We targeted all nurses and doctors working in three governmental hospitals in the Gaza Strip who worked with victims of the 2014 war, more specifically, those who were working in emergency departments, intensive care units, operating rooms, surgical departments, and burn units. A demographic sheet and Impact Event Scale-Revised were used in this study. The Impact Event Scale-Revised has three sub-scales; intrusion, avoidance, and hyper-arousal. Results: The results showed that 291 (89.3%) out of 2444 participants had scores more than 35 (threshold cut-off point) on Impact Event Scale-Revised. Scores ranged from eight to 80 with a mean of 52.71. Females had higher levels of stress (55.33) than males (50.82) and nurses (52.67) had more stress than physicians (47.38). The most frequent symptoms of trauma subscales was “Intrusion” (mean=19.99), followed by “Avoidance” (mean=17.60), and then “Hyper-arousal” (mean=14.12). Level of trauma symptoms were not affected by place of living, hospital of work, while level of education had impacted level of trauma. Conclusion: The findings showed that health care providers still suffer from severe posttraumatic symptoms two years after exposure to a prolonged war stress. This level of trauma among health care providers warrants intervention programs to reduce stress and trauma among Gaza health care providers after the war

Heuristic-based programable controller for efficient energy management under renewable energy sources and energy storage system in smart grid

An operative and versatile household energy management system is proposed to develop and implement demand response (DR) projects. These are under the hybrid generation of the energy storage system (ESS), photovoltaic (PV), and electric vehicles (EVs) in the smart grid (SG). Existing household energy management systems cannot offer its users a choice to ensure user comfort (UC) and not provide a sustainable solution in terms of reduced carbon emission. To tackle these problems, this research work proposes a heuristic-based programmable energy management controller (HPEMC) to manage the energy consumption in residential buildings to minimize electricity bills, reduce carbon emissions, maximize UC and reduce the peak-to-average ratio (PAR). We used our proposed hybrid genetic particle swarm optimization (HGPO) algorithm and existing algorithms like a genetic algorithm (GA), binary particle swarm optimization algorithm (BPSO), ant colony optimization (ACO), wind-driven optimization algorithm (WDO), bacterial foraging algorithm (BFA) to schedule smart appliances optimally to attain our desired objectives. In the proposed model, consumers use solar panels to produce their energy from microgrids. We also perform MATLAB simulations to validate our proposed HGPO-HPEMC (HHPEMC), and results confirm the efficiency and productivity of our proposed HPEMC based strategy. The proposed algorithm reduced the electricity cost by 25.55%, PAR by 36.98%, and carbon emission by 24.02% as compared to the case of without scheduling

Influences of geometrical parameters on the heat transfer characteristics through symmetry trapezoidal-corrugated channel using SiO2-water nanofluid

Enhancing the geometrical parameters design of thermal devices leads to promote the thermal performance and boost design plan of these devices and make it more compact. In the current study, heat transfer and flow characteristics of the symmetry trapezoidal-corrugated channel with silicon dioxide (SiO2) - water as nanofluid was performed numerically over Reynolds number ranges of 10,000–30,000. The influence of geometrical parameters including height-to-width ratio (h/W) and pitch-to-length ratio (p/L) on the thermal and hydraulic characteristics are evaluated. A numerical simulation covers nanofluid with SiO2 volume fractions 8% and carried out by employing the finite volume method (FVM) and SIMPLE algorithm for discretization of the governing equations and coupling of the pressure-velocity system while the k−ε turbulence model was employed to compute the turbulent flow. The outcomes revealed that the (h/W) ratio has a more influence on the promotion of heat transfer compared with the (p/L) ratio. At Reynolds number 30000, there is 16.63% increment in Nuav due to a decrease of the (p/L) ratio from 0.175 to 0.075, while the increment about 99.45% due to an increase of the (h/W) ratio from 0.0 to 0.05. The numerical results indicate that the h/W of 0.05 with a p/L of 0.075 are the optimum parameters and have shown significant improvement in thermal performance factor. Furthermore, new correlations for Nusselt number and friction factor are developed and reported

Catalytic conversion of furfural extract from lubricating oil extraction unit over the shaped and promoted HY catalysts to valuable petroleum products

Catalytic conversion of a furfural extract from the extraction unit of lubricating oil to valuable products was investigated over the shaped HY extrudates using bentonite as binder (HY/bentonite) and zinc and nickel promoted HY/bentonite catalyst (Zn-Ni-HY/bentonite) in a bench scale fixed bed reactor. The catalysts were characterized by XRF, XRD, SEM and nitrogen adsorption-desorption. At 550 °C and LHSV of 9.2 h-1, 7.3 wt% gasoline was yielded over HY/bentonite catalyst, which was significantly increased (ca. 42%) over Zn-Ni-HY/bentonite catalyst. Besides, notably enhanced yield of light and heavy naphtha, kerosene, gas oil and lubricating oil can be distilled from the overall liquid products over Zn-Ni-HY/bentonite catalyst (90.5 wt%) than over HY/bentonite catalyst (77.6 wt%). The obtained petroleum products with the satisfied characteristics can be blended after hydrodesulfurization processing

Medical Students’ Perceptions of Peer Assessment in a Problem-based Learning Curriculum

Objectives: Peer assessment (PA) is believed to support learning and help students develop both professionally and personally. The aim of this study was to examine medical students’ perceptions of intragroup PA in a problem-based learning (PBL) setting. Methods: This study was carried out between September and November 2014 and involved six random groups of fourth-year undergraduate medical students (n = 60) enrolled at the Arabian Gulf University in Manama, Bahrain. While working on set tasks within a curriculum unit, each student evaluated a randomly selected peer using an English language adapted assessment tool to measure responsibility and respect, information processing, critical analysis, interaction and collaborative skills. At the end of the unit, students’ perceptions of PA were identified using a specifically-designed voluntary and anonymous selfadministered questionnaire in English. Results: A total of 55 students participated in the study (response rate: 92%). The majority of students reported that their learning (60%), attendance (67%), respect towards group members (70%) and participation in group discussions (71%) improved as a result of PA. Regarding problem analysis skills, most participants believed that PA improved their ability to analyse problems (65%), identify learning needs (64%), fulfil tasks related to the analysis of learning needs (72%) and share knowledge within their group (74%). Lastly, a large proportion of students reported that this form of assessment helped them develop their communication (71%) and self-assessment skills (73%), as well as collaborative abilities (75%). Conclusion: PA was well accepted by the students in this cohort and led to self-reported improvements in learning, skills, attitudes, engagement and other indicators of personal and professional development. PA was also perceived to have a positive impact on intragroup attitudes